Semantic Likelihood Models for Bayesian Inference in Human-Robot Interaction

NASA Astrophysics Data System (ADS)

Sweet, Nicholas

Autonomous systems, particularly unmanned aerial systems (UAS), remain limited in au- tonomous capabilities largely due to a poor understanding of their environment. Current sensors simply do not match human perceptive capabilities, impeding progress towards full autonomy. Recent work has shown the value of humans as sources of information within a human-robot team; in target applications, communicating human-generated 'soft data' to autonomous systems enables higher levels of autonomy through large, efficient information gains. This requires development of a 'human sensor model' that allows soft data fusion through Bayesian inference to update the probabilistic belief representations maintained by autonomous systems. Current human sensor models that capture linguistic inputs as semantic information are limited in their ability to generalize likelihood functions for semantic statements: they may be learned from dense data; they do not exploit the contextual information embedded within groundings; and they often limit human input to restrictive and simplistic interfaces. This work provides mechanisms to synthesize human sensor models from constraints based on easily attainable a priori knowledge, develops compression techniques to capture information-dense semantics, and investigates the problem of capturing and fusing semantic information contained within unstructured natural language. A robotic experimental testbed is also developed to validate the above contributions.

A Multilevel Gamma-Clustering Layout Algorithm for Visualization of Biological Networks

PubMed Central

Hruz, Tomas; Lucas, Christoph; Laule, Oliver; Zimmermann, Philip

2013-01-01

Visualization of large complex networks has become an indispensable part of systems biology, where organisms need to be considered as one complex system. The visualization of the corresponding network is challenging due to the size and density of edges. In many cases, the use of standard visualization algorithms can lead to high running times and poorly readable visualizations due to many edge crossings. We suggest an approach that analyzes the structure of the graph first and then generates a new graph which contains specific semantic symbols for regular substructures like dense clusters. We propose a multilevel gamma-clustering layout visualization algorithm (MLGA) which proceeds in three subsequent steps: (i) a multilevel γ-clustering is used to identify the structure of the underlying network, (ii) the network is transformed to a tree, and (iii) finally, the resulting tree which shows the network structure is drawn using a variation of a force-directed algorithm. The algorithm has a potential to visualize very large networks because it uses modern clustering heuristics which are optimized for large graphs. Moreover, most of the edges are removed from the visual representation which allows keeping the overview over complex graphs with dense subgraphs. PMID:23864855

ENHANCED ORGANIC MATTER REMINERALIZATION AND NUTRIENT TURNOVER BY BURROWING SHRIMP POPULATIONS IN YAQUINA BAY, OR

EPA Science Inventory

Burrowing thalassinid shrimp are major ecological components of Pacific Northwest (PNW) estuaries and where they structure large areas of intertidal and shallow subtidal habitat. These crustaceans occur in dense beds (>250 m-2) and dig extensive burrow systems (>1 m) controlling ...

Comparison of entrainment in constant volume and constant flux dense currents over sloping bottoms

NASA Astrophysics Data System (ADS)

Bhaganagar, K.; Nayamatullah, M.; Cenedese, C.

2014-12-01

Three dimensional high resolution large eddy simulations (LES) are employed to simulate lock-exchange and constant flux dense flows over inclined surface with the aim of investigating, visualizing and describing the turbulent structure and the evolution of bottom-propagating compositional density current at the channel bottom. The understanding of dynamics of density current is largely determined by the amount of interfacial mixing or entrainment between the ambient and dense fluids. No previous experimental or numerical studies have been done to estimate entrainment in classical lock-exchange system. The differences in entrainment between the lock-exchange and constant flux are explored. Comparing the results of flat bed with inclined surface results, flow exhibits significant differences near the leading edge or nose of the front of the density currents due to inclination of surface. Further, the instabilities are remarkably enhanced resulting Kelvin-Helmholtz and lobe-cleft type of instabilities arises much earlier in time. In this study, a brief analysis of entrainment on lock-exchange density current is presented using different bed slopes and a set of reduced gravity values (g'). We relate the entrainment value with different flow parameters such as Froude number (Fr) and Reynolds number (Re).

Mechanical Properties of Hydrogel Beads

NASA Astrophysics Data System (ADS)

Criddle, Keely; Benns, Thomas; Shorts, Dan; Feitosa, Klebert

2015-03-01

Fragile solids made of dense disordered packing of bubbles, droplets and grains are able to withstand small stresses by virtue of system-wide force chains that lock the system into a jammed state. The nature of the jamming transition in such soft materials has been the subject of intense research, but despite much effort, a deep understanding remains elusive. In this experiment we study the mechanical properties of hydrogel beads to exploit them as force transducers in densely packed systems. The experiment consists of applying uniaxial planar compressions on the beads, and correlating the force to the bead's strain and contact area. The results show that while the strain scales linearly with the diameter of the contact area, the force and strain are found to obey a power law relation with two distinct exponents at small and large strains. This result leads to a power law dependence of the force on the contact area diameter of the compressed bead.

Scrg1, a novel protein of the CNS is targeted to the large dense-core vesicles in neuronal cells.

PubMed

Dandoy-Dron, Françoise; Griffond, Bernadette; Mishal, Zohar; Tovey, Michael G; Dron, Michel

2003-11-01

Scrapie responsive gene one (Scrg1) is a novel transcript discovered through identification of the genes associated with or responsible for the neurodegenerative changes observed in transmissible spongiform encephalopathies. Scrg1 mRNA is distributed principally in the central nervous system and the cDNA sequence predicts a small cysteine-rich protein 98 amino acids in length, with a N-terminal signal peptide. In this study, we have generated antibodies against the predicted protein and revealed expression of a predominant immunoreactive protein of 10 kDa in mouse brain by Western blot analysis. We have established CAD neuronal cell lines stably expressing Scrg1 to determine its subcellular localization. Several lines of evidence show that the protein is targeted to dense-core vesicles in these cells. (i) Scrg1 is detected by immunocytochemistry as very punctate signals especially in the Golgi apparatus and tips of neurites, suggesting a vesicular localization for the protein. Moreover, Scrg1 exhibits a high degree of colocalization with secretogranin II, a dense-core vesicle marker and a very limited colocalization with markers for small synaptic vesicles. (ii) Scrg1 immunoreactivity is associated with large secretory granules/dense-core vesicles, as indicated by immuno-electron microscopy. (iii) Scrg1 is enriched in fractions of sucrose density gradient where synaptotagmin V, a dense-core vesicle-associated protein, is also enriched. The characteristic punctate immunostaining of Scrg1 is observed in N2A cells transfected with Scrg1 and for the endogenous protein in cultured primary neurons, attesting to the generality of the observations. Our findings strongly suggest that Scrg1 is associated with the secretory pathway of neuronal cells.

Development of low-cost meteorological observation system based on wireless network for poor-visibility occurred by snowstorm

NASA Astrophysics Data System (ADS)

Kobayashi, Y.; Watanabe, K.; Imai, M.; Watanabe, K.; Naruse, N.; Takahashi, Y.

2016-12-01

Hyper-densely monitoring for poor-visibility occurred by snowstorm is needed to make an alert system, because the snowstorm is difficult to predict from the observation only at a representative point. There are some problems in the previous approaches for the poor-visibility monitoring using video analyses or visibility meters; these require a wired network monitoring (a large amount of data: 10MB/sec at least) and the system cost is high (10,000 at each point). Thus, the risk of poor-visibility has been mainly measured at specific point such as airport and mountain pass, and estimated by simulation two dimensionally. To predict it two dimensionally and accurately, we have developed a low-cost meteorological system to observe the snowstorm hyper-densely. We have developed a low-cost visibility meter which works as the reduced intensity of semiconducting laser light when snow particles block off. Our developed system also has a capability of extending a hyper-densely observation in real-time on wireless network using Zigbee; A/D conversion and wireless data sent from temperature and illuminance sensors. We use a semiconducting laser chip (5) for the light source and a reflection mechanism by the use of three mirrors so as to send the light to a non-sensitive illuminance sensor directly. Thus, our visibility detecting system ($500) becomes much cheaper than previous one. We have checked the correlation between the reduced intensity taken by our system and the visibility recorded by conventional video camera. The value for the correlation coefficient was -0.67, which indicates a strong correlation. It means that our developed system is practical. In conclusion, we have developed low-cost meteorological detecting system to observe poor-visibility occurred by snowstorm, having a potential of hyper-densely monitoring on wireless network, and have made sure the practicability.

Redox mediators modify end product distribution in biomass fermentations by mixed ruminal microbes in vitro

USDA-ARS?s Scientific Manuscript database

The fermentation system of mixed ruminal bacteria is capable of generating large amounts of short-chain volatile fatty acids (VFA) via the carboxylate platform in vitro. These VFAs are subject to elongation to larger, more energy-dense products through reverse beta-oxidation. This study examined the...

Colliding Laser-Produced Plasmas on LaPD

NASA Astrophysics Data System (ADS)

Collette, Andrew; Gekelman, Walter

2008-11-01

The expansion and interaction of dense plasmas in the presence of a magnetized background plasma is important in many astrophysical processes. We describe a series of experiments which involve the collision of two dense (initially n > 10^15cm-3) laser-produced plasmas within an ambient, highly magnetized background plasma at the UCLA Large Plasma Device facility. These plasmas form diamagnetic cavities in which a large fraction of the background field (600G) has been expelled. Fast (3ns) camera observations of this experiment recorded complicated structures, including coherent corrugated structures on the bubble surfaces. The data hint at the presence of turbulence in the interaction. In order to directly investigate the evolution of the magnetic field, we developed a novel diagnostic system composed of small (1-mm) 3-axis differential magnetic field probes, in conjunction with a vacuum ceramic motor system capable of sub-micron positioning accuracy. Using an ensemble of magnetic field data from fixed and movable probes, we calculate the cross-spectral function, from which the dominant modes and ultimately the dispersion relation of waves in this region may be deduced.

Influence of a depletion interaction on dynamical heterogeneity in a dense quasi-two-dimensional colloid liquid.

PubMed

Ho, Hau My; Cui, Bianxiao; Repel, Stephen; Lin, Binhua; Rice, Stuart A

2004-11-01

We report the results of digital video microscopy studies of the large particle displacements in a quasi-two-dimensional binary mixture of large (L) and small (S) colloid particles with diameter ratio sigma(L)/sigma(S)=4.65, as a function of the large and small colloid particle densities. As in the case of the one-component quasi-two-dimensional colloid system, the binary mixtures exhibit structural and dynamical heterogeneity. The distribution of large particle displacements over the time scale examined provides evidence for (at least) two different mechanisms of motion, one associated with particles in locally ordered regions and the other associated with particles in locally disordered regions. When rhoL*=Npisigma(L) (2)/4A< or =0.35, the addition of small colloid particles leads to a monotonic decrease in the large particle diffusion coefficient with increasing small particle volume fraction. When rhoL* > or =0.35 the addition of small colloid particles to a dense system of large colloid particles at first leads to an increase in the large particle diffusion coefficient, which is then followed by the expected decrease of the large particle diffusion coefficient with increasing small colloid particle volume fraction. The mode coupling theory of the ideal glass transition in three-dimensional systems makes a qualitative prediction that agrees with the initial increase in the large particle diffusion coefficient with increasing small particle density. Nevertheless, because the structural and dynamical heterogeneities of the quasi-two-dimensional colloid liquid occur within the field of equilibrium states, and the fluctuations generate locally ordered domains rather than just disordered regions of higher and lower density, it is suggested that mode coupling theory does not account for all classes of relevant fluctuations in a quasi-two-dimensional liquid. (c) 2004 American Institute of Physics.

The Presence of Dense Material in the Deep Mantle: Implications for Plate Motion

NASA Astrophysics Data System (ADS)

Stein, C.; Hansen, U.

2017-12-01

The dense material in the deep mantle strongly interacts with the convective flow in the mantle. On the one hand, it has a restoring effect on rising plumes. On the other hand, the dense material is swept about by the flow forming dense piles. Consequently this affects the plate motion and, in particular, the onset time and the style of plate tectonics varies considerably for different model scenarios. In this study we apply a thermochemical mantle convection model combined with a rheological model (temperature- and stress-dependent viscosity) that allows for plate formation according to the convective flow. The model's starting condition is the post-magma ocean period. We analyse a large number of model scenarios ranging from variations in thickness, density and depth of a layer of dense material to different initial temperatures.Furthermore, we present a mechanism in which the dense layer at the core-mantle boundary forms without prescribing the thickness or the density contrast. Due to advection-assisted diffusion, long-lived piles can be established that act on the style of convection and therefore on plate motion. We distinguish between the subduction-triggered regime with early plate tectonics and the plume-triggered regime with a late onset of plate tectonics. The formation of piles by advection-assisted diffusion is a typical phenomenon that appears not only at the lower boundary, but also at internal boundaries that form in the layering phase during the evolution of the system.

Gravity-driven dense granular flows

NASA Astrophysics Data System (ADS)

Ertas, Deniz

2002-03-01

Despite their importance in many areas of science and technology, the emergent physics of hard granular systems remain largely obscure, especially when the packing density approaches that of a jammed system. In particular, I will focus on the rheology of gravity-driven dense granular flows on an incline with a ``rough" bottom in two and three dimensions. We have conducted large-scale molecular dynamics simulations of spheres that interact through linear damped spring or Hertzian force laws with a Coulomb failure criterion(D. Ertaş) et al., Europhys. Lett. 56, 214 (2001); L.E. Silbert et al., Phys. Rev. E 64, 051302 (2001).. This flow geometry produces a constant density profile, and reproduces key features of such flows that have been observed experimentally(O. Pouliquen, Phys. Fluids 11), 542 (1999), such as an angle of repose that depends on flow thickness, steady-state solutions at varying heights for a given inclination angle, and the scaling of the mean particle velocity with pile height (< v > ∝ H^3/2). These successes prompted us to carefully examine the rheology in the interior of the pile by measuring the full stress and strain tensors, which are generally unavailable through experiments. The type of force law has little impact on the behavior of the system. The bulk rheology can be approximately described in terms of extensions of Chapman-Enskog theory to dense packings(L. Bocquet et al.), cond-mat/0112072. However, close to the angle of repose, this description fails near the free surface, which exhibits a rheology dominated by normal stress differences that are small in the bulk. This change in rheology can be qualitatively understood in terms of stress-bearing force networks that are continuously formed by ``gravitational inelastic collapse" and destroyed by the imposed strain.

HID-1 controls formation of large dense core vesicles by influencing cargo sorting and trans-Golgi network acidification

PubMed Central

Hummer, Blake H.; de Leeuw, Noah F.; Burns, Christian; Chen, Lan; Joens, Matthew S.; Hosford, Bethany; Fitzpatrick, James A. J.; Asensio, Cedric S.

2017-01-01

Large dense core vesicles (LDCVs) mediate the regulated release of neuropeptides and peptide hormones. They form at the trans-Golgi network (TGN), where their soluble content aggregates to form a dense core, but the mechanisms controlling biogenesis are still not completely understood. Recent studies have implicated the peripheral membrane protein HID-1 in neuropeptide sorting and insulin secretion. Using CRISPR/Cas9, we generated HID-1 KO rat neuroendocrine cells, and we show that the absence of HID-1 results in specific defects in peptide hormone and monoamine storage and regulated secretion. Loss of HID-1 causes a reduction in the number of LDCVs and affects their morphology and biochemical properties, due to impaired cargo sorting and dense core formation. HID-1 KO cells also exhibit defects in TGN acidification together with mislocalization of the Golgi-enriched vacuolar H+-ATPase subunit isoform a2. We propose that HID-1 influences early steps in LDCV formation by controlling dense core formation at the TGN. PMID:29074564

Pulsar Search Using Supervised Machine Learning

NASA Astrophysics Data System (ADS)

Ford, John M.

2017-05-01

Pulsars are rapidly rotating neutron stars which emit a strong beam of energy through mechanisms that are not entirely clear to physicists. These very dense stars are used by astrophysicists to study many basic physical phenomena, such as the behavior of plasmas in extremely dense environments, behavior of pulsar-black hole pairs, and tests of general relativity. Many of these tasks require a large ensemble of pulsars to provide enough statistical information to answer the scientific questions posed by physicists. In order to provide more pulsars to study, there are several large-scale pulsar surveys underway, which are generating a huge backlog of unprocessed data. Searching for pulsars is a very labor-intensive process, currently requiring skilled people to examine and interpret plots of data output by analysis programs. An automated system for screening the plots will speed up the search for pulsars by a very large factor. Research to date on using machine learning and pattern recognition has not yielded a completely satisfactory system, as systems with the desired near 100% recall have false positive rates that are higher than desired, causing more manual labor in the classification of pulsars. This work proposed to research, identify, propose and develop methods to overcome the barriers to building an improved classification system with a false positive rate of less than 1% and a recall of near 100% that will be useful for the current and next generation of large pulsar surveys. The results show that it is possible to generate classifiers that perform as needed from the available training data. While a false positive rate of 1% was not reached, recall of over 99% was achieved with a false positive rate of less than 2%. Methods of mitigating the imbalanced training and test data were explored and found to be highly effective in enhancing classification accuracy.

Supermassive Black Hole Binaries in High Performance Massively Parallel Direct N-body Simulations on Large GPU Clusters

NASA Astrophysics Data System (ADS)

Spurzem, R.; Berczik, P.; Zhong, S.; Nitadori, K.; Hamada, T.; Berentzen, I.; Veles, A.

2012-07-01

Astrophysical Computer Simulations of Dense Star Clusters in Galactic Nuclei with Supermassive Black Holes are presented using new cost-efficient supercomputers in China accelerated by graphical processing cards (GPU). We use large high-accuracy direct N-body simulations with Hermite scheme and block-time steps, parallelised across a large number of nodes on the large scale and across many GPU thread processors on each node on the small scale. A sustained performance of more than 350 Tflop/s for a science run on using simultaneously 1600 Fermi C2050 GPUs is reached; a detailed performance model is presented and studies for the largest GPU clusters in China with up to Petaflop/s performance and 7000 Fermi GPU cards. In our case study we look at two supermassive black holes with equal and unequal masses embedded in a dense stellar cluster in a galactic nucleus. The hardening processes due to interactions between black holes and stars, effects of rotation in the stellar system and relativistic forces between the black holes are simultaneously taken into account. The simulation stops at the complete relativistic merger of the black holes.

Dense Gas, Dynamical Equilibrium Pressure, and Star Formation in Nearby Star-forming Galaxies

NASA Astrophysics Data System (ADS)

Gallagher, Molly J.; Leroy, Adam K.; Bigiel, Frank; Cormier, Diane; Jiménez-Donaire, María J.; Ostriker, Eve; Usero, Antonio; Bolatto, Alberto D.; García-Burillo, Santiago; Hughes, Annie; Kepley, Amanda A.; Krumholz, Mark; Meidt, Sharon E.; Meier, David S.; Murphy, Eric J.; Pety, Jérôme; Rosolowsky, Erik; Schinnerer, Eva; Schruba, Andreas; Walter, Fabian

2018-05-01

We use new ALMA observations to investigate the connection between dense gas fraction, star formation rate (SFR), and local environment across the inner region of four local galaxies showing a wide range of molecular gas depletion times. We map HCN (1–0), HCO+ (1–0), CS (2–1), 13CO (1–0), and C18O (1–0) across the inner few kiloparsecs of each target. We combine these data with short-spacing information from the IRAM large program EMPIRE, archival CO maps, tracers of stellar structure and recent star formation, and recent HCN surveys by Bigiel et al. and Usero et al. We test the degree to which changes in the dense gas fraction drive changes in the SFR. {I}HCN}/{I}CO} (tracing the dense gas fraction) correlates strongly with I CO (tracing molecular gas surface density), stellar surface density, and dynamical equilibrium pressure, P DE. Therefore, {I}HCN}/{I}CO} becomes very low and HCN becomes very faint at large galactocentric radii, where ratios as low as {I}HCN}/{I}CO}∼ 0.01 become common. The apparent ability of dense gas to form stars, {{{Σ }}}SFR}/{{{Σ }}}dense} (where Σdense is traced by the HCN intensity and the star formation rate is traced by a combination of Hα and 24 μm emission), also depends on environment. {{{Σ }}}SFR}/{{{Σ }}}dense} decreases in regions of high gas surface density, high stellar surface density, and high P DE. Statistically, these correlations between environment and both {{{Σ }}}SFR}/{{{Σ }}}dense} and {I}HCN}/{I}CO} are stronger than that between apparent dense gas fraction ({I}HCN}/{I}CO}) and the apparent molecular gas star formation efficiency {{{Σ }}}SFR}/{{{Σ }}}mol}. We show that these results are not specific to HCN.

Self-assembly in densely grafted macromolecules with amphiphilic monomer units: diagram of states.

PubMed

Lazutin, A A; Vasilevskaya, V V; Khokhlov, A R

2017-11-22

By means of computer modelling, the self-organization of dense planar brushes of macromolecules with amphiphilic monomer units was addressed and their state diagram was constructed. The diagram of states includes the following regions: disordered position of monomer units with respect to each other, strands composed of a few polymer chains and lamellae with different domain spacing. The transformation of lamellae structures with different domain spacing occurred within the intermediate region and could proceed through the formation of so-called parking garage structures. The parking garage structure joins the lamellae with large (on the top of the brushes) and small (close to the grafted surface) domain spacing, which appears like a system of inclined locally parallel layers connected with each other by bridges. The parking garage structures were observed for incompatible A and B groups in selective solvents, which result in aggregation of the side B groups and dense packing of amphiphilic macromolecules in the restricted volume of the planar brushes.

BDNF and its pro-peptide are stored in presynaptic dense core vesicles in brain neurons

PubMed Central

Dieni, Sandra; Matsumoto, Tomoya; Dekkers, Martijn; Rauskolb, Stefanie; Ionescu, Mihai S.; Deogracias, Ruben; Gundelfinger, Eckart D.; Kojima, Masami; Nestel, Sigrun; Frotscher, Michael

2012-01-01

Although brain-derived neurotrophic factor (BDNF) regulates numerous and complex biological processes including memory retention, its extremely low levels in the mature central nervous system have greatly complicated attempts to reliably localize it. Using rigorous specificity controls, we found that antibodies reacting either with BDNF or its pro-peptide both stained large dense core vesicles in excitatory presynaptic terminals of the adult mouse hippocampus. Both moieties were ∼10-fold more abundant than pro-BDNF. The lack of postsynaptic localization was confirmed in Bassoon mutants, a seizure-prone mouse line exhibiting markedly elevated levels of BDNF. These findings challenge previous conclusions based on work with cultured neurons, which suggested activity-dependent dendritic synthesis and release of BDNF. They instead provide an ultrastructural basis for an anterograde mode of action of BDNF, contrasting with the long-established retrograde model derived from experiments with nerve growth factor in the peripheral nervous system. PMID:22412021

Construction of the 16 meter Large Lunar Telescope (LLT)

NASA Technical Reports Server (NTRS)

Omar, Husam Anwar

1990-01-01

The different materials that could be used to design the pedestal for a Moon based 16 meter telescope are discussed. The material that should be used has a low coefficient of thermal expansion, high modulus of elasticity, and high compressive and tensile strengths. For the model developed in this study, an aluminum-manganese alloy was used because of its low coefficient of thermal expansion. Due to variations in lunar soil conditions, both vertically and horizontally, three foundation systems are presented. The spudcan footing can be used in the case where dense soil is more than three meters. The spread footing is recommended where the dense soil is between one and three meters. Finally, in the third system, the Lunar Excursion Vehicle (LEV) is used as a base support for the telescope's pedestal. The LEV support requires a prepared site. The soil should be compacted and stabilized, if necessary, to reduce settlement.

A parallel solver for huge dense linear systems

NASA Astrophysics Data System (ADS)

Badia, J. M.; Movilla, J. L.; Climente, J. I.; Castillo, M.; Marqués, M.; Mayo, R.; Quintana-Ortí, E. S.; Planelles, J.

2011-11-01

HDSS (Huge Dense Linear System Solver) is a Fortran Application Programming Interface (API) to facilitate the parallel solution of very large dense systems to scientists and engineers. The API makes use of parallelism to yield an efficient solution of the systems on a wide range of parallel platforms, from clusters of processors to massively parallel multiprocessors. It exploits out-of-core strategies to leverage the secondary memory in order to solve huge linear systems O(100.000). The API is based on the parallel linear algebra library PLAPACK, and on its Out-Of-Core (OOC) extension POOCLAPACK. Both PLAPACK and POOCLAPACK use the Message Passing Interface (MPI) as the communication layer and BLAS to perform the local matrix operations. The API provides a friendly interface to the users, hiding almost all the technical aspects related to the parallel execution of the code and the use of the secondary memory to solve the systems. In particular, the API can automatically select the best way to store and solve the systems, depending of the dimension of the system, the number of processes and the main memory of the platform. Experimental results on several parallel platforms report high performance, reaching more than 1 TFLOP with 64 cores to solve a system with more than 200 000 equations and more than 10 000 right-hand side vectors. New version program summaryProgram title: Huge Dense System Solver (HDSS) Catalogue identifier: AEHU_v1_1 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHU_v1_1.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 87 062 No. of bytes in distributed program, including test data, etc.: 1 069 110 Distribution format: tar.gz Programming language: Fortran90, C Computer: Parallel architectures: multiprocessors, computer clusters Operating system: Linux/Unix Has the code been vectorized or parallelized?: Yes, includes MPI primitives. RAM: Tested for up to 190 GB Classification: 6.5 External routines: MPI ( http://www.mpi-forum.org/), BLAS ( http://www.netlib.org/blas/), PLAPACK ( http://www.cs.utexas.edu/~plapack/), POOCLAPACK ( ftp://ftp.cs.utexas.edu/pub/rvdg/PLAPACK/pooclapack.ps) (code for PLAPACK and POOCLAPACK is included in the distribution). Catalogue identifier of previous version: AEHU_v1_0 Journal reference of previous version: Comput. Phys. Comm. 182 (2011) 533 Does the new version supersede the previous version?: Yes Nature of problem: Huge scale dense systems of linear equations, Ax=B, beyond standard LAPACK capabilities. Solution method: The linear systems are solved by means of parallelized routines based on the LU factorization, using efficient secondary storage algorithms when the available main memory is insufficient. Reasons for new version: In many applications we need to guarantee a high accuracy in the solution of very large linear systems and we can do it by using double-precision arithmetic. Summary of revisions: Version 1.1 Can be used to solve linear systems using double-precision arithmetic. New version of the initialization routine. The user can choose the kind of arithmetic and the values of several parameters of the environment. Running time: About 5 hours to solve a system with more than 200 000 equations and more than 10 000 right-hand side vectors using double-precision arithmetic on an eight-node commodity cluster with a total of 64 Intel cores.

A Novel Characterization of Amalgamated Networks in Natural Systems

PubMed Central

Barranca, Victor J.; Zhou, Douglas; Cai, David

2015-01-01

Densely-connected networks are prominent among natural systems, exhibiting structural characteristics often optimized for biological function. To reveal such features in highly-connected networks, we introduce a new network characterization determined by a decomposition of network-connectivity into low-rank and sparse components. Based on these components, we discover a new class of networks we define as amalgamated networks, which exhibit large functional groups and dense connectivity. Analyzing recent experimental findings on cerebral cortex, food-web, and gene regulatory networks, we establish the unique importance of amalgamated networks in fostering biologically advantageous properties, including rapid communication among nodes, structural stability under attacks, and separation of network activity into distinct functional modules. We further observe that our network characterization is scalable with network size and connectivity, thereby identifying robust features significant to diverse physical systems, which are typically undetectable by conventional characterizations of connectivity. We expect that studying the amalgamation properties of biological networks may offer new insights into understanding their structure-function relationships. PMID:26035066

Massively parallel algorithms for real-time wavefront control of a dense adaptive optics system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fijany, A.; Milman, M.; Redding, D.

1994-12-31

In this paper massively parallel algorithms and architectures for real-time wavefront control of a dense adaptive optic system (SELENE) are presented. The authors have already shown that the computation of a near optimal control algorithm for SELENE can be reduced to the solution of a discrete Poisson equation on a regular domain. Although, this represents an optimal computation, due the large size of the system and the high sampling rate requirement, the implementation of this control algorithm poses a computationally challenging problem since it demands a sustained computational throughput of the order of 10 GFlops. They develop a novel algorithm,more » designated as Fast Invariant Imbedding algorithm, which offers a massive degree of parallelism with simple communication and synchronization requirements. Due to these features, this algorithm is significantly more efficient than other Fast Poisson Solvers for implementation on massively parallel architectures. The authors also discuss two massively parallel, algorithmically specialized, architectures for low-cost and optimal implementation of the Fast Invariant Imbedding algorithm.« less

970-nm ridge waveguide diode laser bars for high power DWBC systems

NASA Astrophysics Data System (ADS)

Wilkens, Martin; Erbert, Götz; Wenzel, Hans; Knigge, Andrea; Crump, Paul; Maaßdorf, Andre; Fricke, Jörg; Ressel, Peter; Strohmaier, Stephan; Schmidt, Berthold; Tränkle, Günther

2018-02-01

de lasers are key components in material processing laser systems. While mostly used as pump sources for solid state or fiber lasers, direct diode laser systems using dense wavelength multiplexing have come on the market in recent years. These systems are realized with broad area lasers typically, resulting in beam quality inferior to disk or fiber lasers. We will present recent results of highly efficient ridge waveguide (RW) lasers, developed for dense-wavelength-beamcombining (DWBC) laser systems expecting beam qualities comparable to solid state laser systems and higher power conversion efficiencies (PCE). The newly developed RW lasers are based on vertical structures with an extreme double asymmetric large optical cavity. Besides a low vertical divergence these structures are suitable for RW-lasers with (10 μm) broad ridges, emitting in a single mode with a good beam quality. The large stripe width enables a lateral divergence below 10° (95 % power content) and a high PCE by a comparably low series resistance. We present results of single emitters and small test arrays under different external feedback conditions. Single emitters can be tuned from 950 nm to 975 nm and reach 1 W optical power with more than 55 % PCE and a beam quality of M2 < 2 over the full wavelength range. The spectral width is below 30 pm FWHM. 5 emitter arrays were stabilized using the same setup. Up to now we reached 3 W optical power, limited by power supply, with 5 narrow spectral lines.

Dense module enumeration in biological networks

NASA Astrophysics Data System (ADS)

Tsuda, Koji; Georgii, Elisabeth

2009-12-01

Analysis of large networks is a central topic in various research fields including biology, sociology, and web mining. Detection of dense modules (a.k.a. clusters) is an important step to analyze the networks. Though numerous methods have been proposed to this aim, they often lack mathematical rigorousness. Namely, there is no guarantee that all dense modules are detected. Here, we present a novel reverse-search-based method for enumerating all dense modules. Furthermore, constraints from additional data sources such as gene expression profiles or customer profiles can be integrated, so that we can systematically detect dense modules with interesting profiles. We report successful applications in human protein interaction network analyses.

Dense wavelength division multiplexing devices for metropolitan-area datacom and telecom networks

NASA Astrophysics Data System (ADS)

DeCusatis, Casimer M.; Priest, David G.

2000-12-01

Large data processing environments in use today can require multi-gigabyte or terabyte capacity in the data communication infrastructure; these requirements are being driven by storage area networks with access to petabyte data bases, new architecture for parallel processing which require high bandwidth optical links, and rapidly growing network applications such as electronic commerce over the Internet or virtual private networks. These datacom applications require high availability, fault tolerance, security, and the capacity to recover from any single point of failure without relying on traditional SONET-based networking. These requirements, coupled with fiber exhaust in metropolitan areas, are driving the introduction of dense optical wavelength division multiplexing (DWDM) in data communication systems, particularly for large enterprise servers or mainframes. In this paper, we examine the technical requirements for emerging nextgeneration DWDM systems. Protocols for storage area networks and computer architectures such as Parallel Sysplex are presented, including their fiber bandwidth requirements. We then describe two commercially available DWDM solutions, a first generation 10 channel system and a recently announced next generation 32 channel system. Technical requirements, network management and security, fault tolerant network designs, new network topologies enabled by DWDM, and the role of time division multiplexing in the network are all discussed. Finally, we present a description of testing conducted on these networks and future directions for this technology.

Production and early field performance of RPM® seedlings in Missouri floodplains

Treesearch

Daniel C. Dey; Wayne Lovelace; John M. Kabrick; Michael A. Gold

2004-01-01

A new nursery culture process has been developed to produce large container RPM? seedlings in an effort to improve the success in artificially regenerating hardwoods. Major features of the process include air root pruning of seedlings grown in a well aerated soil medium to encourage a dense, fibrous root system. Production has focused on native bottomland tree, shrub,...

Globular Cluster Systems in Interacting Galaxies

NASA Astrophysics Data System (ADS)

Zepf, S.; Murdin, P.

2000-11-01

GLOBULAR CLUSTERS are dynamically bound and dense collections of large numbers of coeval stars. Typical globular clusters have roughly one million stars within a radius of a few parsecs. They are also usually close to spherical, hence the name globular. By virtue of their rich, isolated population of stars they provide an important laboratory for studies of STELLAR EVOLUTION. Moreover, because of...

Ionization-potential depression and dynamical structure factor in dense plasmas

NASA Astrophysics Data System (ADS)

Lin, Chengliang; Röpke, Gerd; Kraeft, Wolf-Dietrich; Reinholz, Heidi

2017-07-01

The properties of a bound electron system immersed in a plasma environment are strongly modified by the surrounding plasma. The modification of an essential quantity, the ionization energy, is described by the electronic and ionic self-energies, including dynamical screening within the framework of the quantum statistical theory. Introducing the ionic dynamical structure factor as the indicator for the ionic microfield, we demonstrate that ionic correlations and fluctuations play a critical role in determining the ionization potential depression. This is, in particular, true for mixtures of different ions with large mass and charge asymmetry. The ionization potential depression is calculated for dense aluminum plasmas as well as for a CH plasma and compared to the experimental data and more phenomenological approaches used so far.

Efficient Implementation of an Optimal Interpolator for Large Spatial Data Sets

NASA Technical Reports Server (NTRS)

Memarsadeghi, Nargess; Mount, David M.

2007-01-01

Interpolating scattered data points is a problem of wide ranging interest. A number of approaches for interpolation have been proposed both from theoretical domains such as computational geometry and in applications' fields such as geostatistics. Our motivation arises from geological and mining applications. In many instances data can be costly to compute and are available only at nonuniformly scattered positions. Because of the high cost of collecting measurements, high accuracy is required in the interpolants. One of the most popular interpolation methods in this field is called ordinary kriging. It is popular because it is a best linear unbiased estimator. The price for its statistical optimality is that the estimator is computationally very expensive. This is because the value of each interpolant is given by the solution of a large dense linear system. In practice, kriging problems have been solved approximately by restricting the domain to a small local neighborhood of points that lie near the query point. Determining the proper size for this neighborhood is a solved by ad hoc methods, and it has been shown that this approach leads to undesirable discontinuities in the interpolant. Recently a more principled approach to approximating kriging has been proposed based on a technique called covariance tapering. This process achieves its efficiency by replacing the large dense kriging system with a much sparser linear system. This technique has been applied to a restriction of our problem, called simple kriging, which is not unbiased for general data sets. In this paper we generalize these results by showing how to apply covariance tapering to the more general problem of ordinary kriging. Through experimentation we demonstrate the space and time efficiency and accuracy of approximating ordinary kriging through the use of covariance tapering combined with iterative methods for solving large sparse systems. We demonstrate our approach on large data sizes arising both from synthetic sources and from real applications.

Parametric dense stereovision implementation on a system-on chip (SoC).

PubMed

Gardel, Alfredo; Montejo, Pablo; García, Jorge; Bravo, Ignacio; Lázaro, José L

2012-01-01

This paper proposes a novel hardware implementation of a dense recovery of stereovision 3D measurements. Traditionally 3D stereo systems have imposed the maximum number of stereo correspondences, introducing a large restriction on artificial vision algorithms. The proposed system-on-chip (SoC) provides great performance and efficiency, with a scalable architecture available for many different situations, addressing real time processing of stereo image flow. Using double buffering techniques properly combined with pipelined processing, the use of reconfigurable hardware achieves a parametrisable SoC which gives the designer the opportunity to decide its right dimension and features. The proposed architecture does not need any external memory because the processing is done as image flow arrives. Our SoC provides 3D data directly without the storage of whole stereo images. Our goal is to obtain high processing speed while maintaining the accuracy of 3D data using minimum resources. Configurable parameters may be controlled by later/parallel stages of the vision algorithm executed on an embedded processor. Considering hardware FPGA clock of 100 MHz, image flows up to 50 frames per second (fps) of dense stereo maps of more than 30,000 depth points could be obtained considering 2 Mpix images, with a minimum initial latency. The implementation of computer vision algorithms on reconfigurable hardware, explicitly low level processing, opens up the prospect of its use in autonomous systems, and they can act as a coprocessor to reconstruct 3D images with high density information in real time.

Dynamics of dense granular flows of small-and-large-grain mixtures in an ambient fluid.

PubMed

Meruane, C; Tamburrino, A; Roche, O

2012-08-01

Dense grain flows in nature consist of a mixture of solid constituents that are immersed in an ambient fluid. In order to obtain a good representation of these flows, the interaction mechanisms between the different constituents of the mixture should be considered. In this article, we study the dynamics of a dense granular flow composed of a binary mixture of small and large grains immersed in an ambient fluid. In this context, we extend the two-phase approach proposed by Meruane et al. [J. Fluid Mech. 648, 381 (2010)] to the case of flowing dense binary mixtures of solid particles, by including in the momentum equations a constitutive relation that describes the interaction mechanisms between the solid constituents in a dense regime. These coupled equations are solved numerically and validated by comparing the numerical results with experimental measurements of the front speed of gravitational granular flows resulting from the collapse, in ambient air or water, of two-dimensional granular columns that consisted of mixtures of small and large spherical particles of equal mass density. Our results suggest that the model equations include the essential features that describe the dynamics of grains flows of binary mixtures in an ambient fluid. In particular, it is shown that segregation of small and large grains can increase the front speed because of the volumetric expansion of the flow. This increase in flow speed is damped by the interaction forces with the ambient fluid, and this behavior is more pronounced in water than in air.

Mining connected global and local dense subgraphs for bigdata

NASA Astrophysics Data System (ADS)

Wu, Bo; Shen, Haiying

2016-01-01

The problem of discovering connected dense subgraphs of natural graphs is important in data analysis. Discovering dense subgraphs that do not contain denser subgraphs or are not contained in denser subgraphs (called significant dense subgraphs) is also critical for wide-ranging applications. In spite of many works on discovering dense subgraphs, there are no algorithms that can guarantee the connectivity of the returned subgraphs or discover significant dense subgraphs. Hence, in this paper, we define two subgraph discovery problems to discover connected and significant dense subgraphs, propose polynomial-time algorithms and theoretically prove their validity. We also propose an algorithm to further improve the time and space efficiency of our basic algorithm for discovering significant dense subgraphs in big data by taking advantage of the unique features of large natural graphs. In the experiments, we use massive natural graphs to evaluate our algorithms in comparison with previous algorithms. The experimental results show the effectiveness of our algorithms for the two problems and their efficiency. This work is also the first that reveals the physical significance of significant dense subgraphs in natural graphs from different domains.

A Dense Poly(ethylene glycol) Coating Improves Penetration of Large Polymeric Nanoparticles within Brain Tissue

PubMed Central

Nance, Elizabeth A.; Woodworth, Graeme F.; Sailor, Kurt A.; Shih, Ting-Yu; Xu, Qingguo; Swaminathan, Ganesh; Xiang, Dennis; Eberhart, Charles; Hanes, Justin

2013-01-01

Prevailing opinion suggests that only substances up to 64 nm in diameter can move at appreciable rates through the brain extracellular space (ECS). This size range is large enough to allow diffusion of signaling molecules, nutrients, and metabolic waste products, but too small to allow efficient penetration of most particulate drug delivery systems and viruses carrying therapeutic genes, thereby limiting effectiveness of many potential therapies. We analyzed the movements of nanoparticles of various diameters and surface coatings within fresh human and rat brain tissue ex vivo and mouse brain in vivo. Nanoparticles as large as 114-nm in diameter diffused within the human and rat brain, but only if they were densely coated with poly(ethylene glycol) (PEG). Using these minimally adhesive PEG-coated particles, we estimated that human brain tissue ECS has some pores larger than 200 nm, and that more than one-quarter of all pores are ≥100 nm. These findings were confirmed in vivo in mice, where 40- and 100-nm, but not 200-nm, nanoparticles, spread rapidly within brain tissue, only if densely coated with PEG. Similar results were observed in rat brain tissue with paclitaxel-loaded biodegradable nanoparticles of similar size (85 nm) and surface properties. The ability to achieve brain penetration with larger nanoparticles is expected to allow more uniform, longer-lasting, and effective delivery of drugs within the brain, and may find use in the treatment of brain tumors, stroke, neuroinflammation, and other brain diseases where the blood-brain barrier is compromised or where local delivery strategies are feasible. PMID:22932224

Reconstruction of in-plane strain maps using hybrid dense sensor network composed of sensing skin

NASA Astrophysics Data System (ADS)

Downey, Austin; Laflamme, Simon; Ubertini, Filippo

2016-12-01

The authors have recently developed a soft-elastomeric capacitive (SEC)-based thin film sensor for monitoring strain on mesosurfaces. Arranged in a network configuration, the sensing system is analogous to a biological skin, where local strain can be monitored over a global area. Under plane stress conditions, the sensor output contains the additive measurement of the two principal strain components over the monitored surface. In applications where the evaluation of strain maps is useful, in structural health monitoring for instance, such signal must be decomposed into linear strain components along orthogonal directions. Previous work has led to an algorithm that enabled such decomposition by leveraging a dense sensor network configuration with the addition of assumed boundary conditions. Here, we significantly improve the algorithm’s accuracy by leveraging mature off-the-shelf solutions to create a hybrid dense sensor network (HDSN) to improve on the boundary condition assumptions. The system’s boundary conditions are enforced using unidirectional RSGs and assumed virtual sensors. Results from an extensive experimental investigation demonstrate the good performance of the proposed algorithm and its robustness with respect to sensors’ layout. Overall, the proposed algorithm is seen to effectively leverage the advantages of a hybrid dense network for application of the thin film sensor to reconstruct surface strain fields over large surfaces.

Benchmarking variable-density flow in saturated and unsaturated porous media

NASA Astrophysics Data System (ADS)

Guevara Morel, Carlos Roberto; Cremer, Clemens; Graf, Thomas

2015-04-01

In natural environments, fluid density and viscosity can be affected by spatial and temporal variations of solute concentration and/or temperature. These variations can occur, for example, due to salt water intrusion in coastal aquifers, leachate infiltration from waste disposal sites and upconing of saline water from deep aquifers. As a consequence, potentially unstable situations may exist in which a dense fluid overlies a less dense fluid. This situation can produce instabilities that manifest as dense plume fingers that move vertically downwards counterbalanced by vertical upwards flow of the less dense fluid. Resulting free convection increases solute transport rates over large distances and times relative to constant-density flow. Therefore, the understanding of free convection is relevant for the protection of freshwater aquifer systems. The results from a laboratory experiment of saturated and unsaturated variable-density flow and solute transport (Simmons et al., Transp. Porous Medium, 2002) are used as the physical basis to define a mathematical benchmark. The HydroGeoSphere code coupled with PEST are used to estimate the optimal parameter set capable of reproducing the physical model. A grid convergency analysis (in space and time) is also undertaken in order to obtain the adequate spatial and temporal discretizations. The new mathematical benchmark is useful for model comparison and testing of variable-density variably saturated flow in porous media.

A Distributed-Memory Package for Dense Hierarchically Semi-Separable Matrix Computations Using Randomization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rouet, François-Henry; Li, Xiaoye S.; Ghysels, Pieter

In this paper, we present a distributed-memory library for computations with dense structured matrices. A matrix is considered structured if its off-diagonal blocks can be approximated by a rank-deficient matrix with low numerical rank. Here, we use Hierarchically Semi-Separable (HSS) representations. Such matrices appear in many applications, for example, finite-element methods, boundary element methods, and so on. Exploiting this structure allows for fast solution of linear systems and/or fast computation of matrix-vector products, which are the two main building blocks of matrix computations. The compression algorithm that we use, that computes the HSS form of an input dense matrix, reliesmore » on randomized sampling with a novel adaptive sampling mechanism. We discuss the parallelization of this algorithm and also present the parallelization of structured matrix-vector product, structured factorization, and solution routines. The efficiency of the approach is demonstrated on large problems from different academic and industrial applications, on up to 8,000 cores. Finally, this work is part of a more global effort, the STRUctured Matrices PACKage (STRUMPACK) software package for computations with sparse and dense structured matrices. Hence, although useful on their own right, the routines also represent a step in the direction of a distributed-memory sparse solver.« less

A Distributed-Memory Package for Dense Hierarchically Semi-Separable Matrix Computations Using Randomization

DOE PAGES

Rouet, François-Henry; Li, Xiaoye S.; Ghysels, Pieter; ...

2016-06-30

In this paper, we present a distributed-memory library for computations with dense structured matrices. A matrix is considered structured if its off-diagonal blocks can be approximated by a rank-deficient matrix with low numerical rank. Here, we use Hierarchically Semi-Separable (HSS) representations. Such matrices appear in many applications, for example, finite-element methods, boundary element methods, and so on. Exploiting this structure allows for fast solution of linear systems and/or fast computation of matrix-vector products, which are the two main building blocks of matrix computations. The compression algorithm that we use, that computes the HSS form of an input dense matrix, reliesmore » on randomized sampling with a novel adaptive sampling mechanism. We discuss the parallelization of this algorithm and also present the parallelization of structured matrix-vector product, structured factorization, and solution routines. The efficiency of the approach is demonstrated on large problems from different academic and industrial applications, on up to 8,000 cores. Finally, this work is part of a more global effort, the STRUctured Matrices PACKage (STRUMPACK) software package for computations with sparse and dense structured matrices. Hence, although useful on their own right, the routines also represent a step in the direction of a distributed-memory sparse solver.« less

A Low Collision and High Throughput Data Collection Mechanism for Large-Scale Super Dense Wireless Sensor Networks.

PubMed

Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Gaura, Elena; Brusey, James; Zhang, Xuekun; Dutkiewicz, Eryk

2016-07-18

Super dense wireless sensor networks (WSNs) have become popular with the development of Internet of Things (IoT), Machine-to-Machine (M2M) communications and Vehicular-to-Vehicular (V2V) networks. While highly-dense wireless networks provide efficient and sustainable solutions to collect precise environmental information, a new channel access scheme is needed to solve the channel collision problem caused by the large number of competing nodes accessing the channel simultaneously. In this paper, we propose a space-time random access method based on a directional data transmission strategy, by which collisions in the wireless channel are significantly decreased and channel utility efficiency is greatly enhanced. Simulation results show that our proposed method can decrease the packet loss rate to less than 2 % in large scale WSNs and in comparison with other channel access schemes for WSNs, the average network throughput can be doubled.

Module discovery by exhaustive search for densely connected, co-expressed regions in biomolecular interaction networks.

PubMed

Colak, Recep; Moser, Flavia; Chu, Jeffrey Shih-Chieh; Schönhuth, Alexander; Chen, Nansheng; Ester, Martin

2010-10-25

Computational prediction of functionally related groups of genes (functional modules) from large-scale data is an important issue in computational biology. Gene expression experiments and interaction networks are well studied large-scale data sources, available for many not yet exhaustively annotated organisms. It has been well established, when analyzing these two data sources jointly, modules are often reflected by highly interconnected (dense) regions in the interaction networks whose participating genes are co-expressed. However, the tractability of the problem had remained unclear and methods by which to exhaustively search for such constellations had not been presented. We provide an algorithmic framework, referred to as Densely Connected Biclustering (DECOB), by which the aforementioned search problem becomes tractable. To benchmark the predictive power inherent to the approach, we computed all co-expressed, dense regions in physical protein and genetic interaction networks from human and yeast. An automatized filtering procedure reduces our output which results in smaller collections of modules, comparable to state-of-the-art approaches. Our results performed favorably in a fair benchmarking competition which adheres to standard criteria. We demonstrate the usefulness of an exhaustive module search, by using the unreduced output to more quickly perform GO term related function prediction tasks. We point out the advantages of our exhaustive output by predicting functional relationships using two examples. We demonstrate that the computation of all densely connected and co-expressed regions in interaction networks is an approach to module discovery of considerable value. Beyond confirming the well settled hypothesis that such co-expressed, densely connected interaction network regions reflect functional modules, we open up novel computational ways to comprehensively analyze the modular organization of an organism based on prevalent and largely available large-scale datasets. Software and data sets are available at http://www.sfu.ca/~ester/software/DECOB.zip.

An intelligent surveillance platform for large metropolitan areas with dense sensor deployment.

PubMed

Fernández, Jorge; Calavia, Lorena; Baladrón, Carlos; Aguiar, Javier M; Carro, Belén; Sánchez-Esguevillas, Antonio; Alonso-López, Jesus A; Smilansky, Zeev

2013-06-07

This paper presents an intelligent surveillance platform based on the usage of large numbers of inexpensive sensors designed and developed inside the European Eureka Celtic project HuSIMS. With the aim of maximizing the number of deployable units while keeping monetary and resource/bandwidth costs at a minimum, the surveillance platform is based on the usage of inexpensive visual sensors which apply efficient motion detection and tracking algorithms to transform the video signal in a set of motion parameters. In order to automate the analysis of the myriad of data streams generated by the visual sensors, the platform's control center includes an alarm detection engine which comprises three components applying three different Artificial Intelligence strategies in parallel. These strategies are generic, domain-independent approaches which are able to operate in several domains (traffic surveillance, vandalism prevention, perimeter security, etc.). The architecture is completed with a versatile communication network which facilitates data collection from the visual sensors and alarm and video stream distribution towards the emergency teams. The resulting surveillance system is extremely suitable for its deployment in metropolitan areas, smart cities, and large facilities, mainly because cheap visual sensors and autonomous alarm detection facilitate dense sensor network deployments for wide and detailed coverage.

Recursive partitioned inversion of large (1500 x 1500) symmetric matrices

NASA Technical Reports Server (NTRS)

Putney, B. H.; Brownd, J. E.; Gomez, R. A.

1976-01-01

A recursive algorithm was designed to invert large, dense, symmetric, positive definite matrices using small amounts of computer core, i.e., a small fraction of the core needed to store the complete matrix. The described algorithm is a generalized Gaussian elimination technique. Other algorithms are also discussed for the Cholesky decomposition and step inversion techniques. The purpose of the inversion algorithm is to solve large linear systems of normal equations generated by working geodetic problems. The algorithm was incorporated into a computer program called SOLVE. In the past the SOLVE program has been used in obtaining solutions published as the Goddard earth models.

INPIStron switched pulsed power for dense plasma pinches

NASA Technical Reports Server (NTRS)

Han, Kwang S.; Lee, Ja H.

1993-01-01

The inverse plasma switch INPIStron was employed for 10kJ/40kV capacitor bank discharge system to produce focused dense plasmas in hypocycloidal-pinch (HCP) devices. A single unit and an array of multiple HCP's were coupled as the load of the pulsed power circuit. The geometry and switching plasma dynamics were found advantageous and convenient for commutating the large current pulse from the low impedance transmission line to the low impedance plasma load. The pulse power system with a single unit HCP, the system A, was used for production of high temperature plasma focus and its diagnostics. The radially running down plasma dynamics, revealed in image converter photographs, could be simulated by a simple snow-plow model with a correction for plasma resistivity. The system B with an array of 8-HCP units which forms a long coaxial discharge chamber was used for pumping a Ti-sapphire laser. The intense UV emission from the plasma was frequency shifted with dye-solution jacket to match the absorption band of the Ti crystal laser near 500 nm. An untuned laser pulse energy of 0.6 J/pulse was obtained for 6.4 kJ/40 kV discharge, or near 103 times of the explosion limit of conventional flash lamps. For both systems the advantages of the INPIStron were well demonstrated: a single unit is sufficient for a large current (greater than 50 kA) without increasing the system impedance, highly reliable and long life operation and implied scalability for the high power ranges above I(sub peak) = 1 MA and V(sub hold) = 100 kV.

Excitonic effects in dense media: breakdown of intrinsic optical bistability

NASA Astrophysics Data System (ADS)

Yudson, V. I.; Reineker, P.

1994-12-01

The steady-state nonlinear response to optical excitation is studied for a thin layer containing “two-level-atoms” (TLA). For a high density of TLAs their dipole-dipole interaction and finite excitonic bandwidth effects become important. We demonstrate that the commonly used local-field approximation ignoring excitonic band effects breaks down. Considering a system of ordered TLAs corresponding to Frenkel excitons in molecular crystals we show that excitonic effects cause an instability of spatially uniform solutions and decrease drastically the existence range of the intrinsic optical bistability of a layer. The possibility of “fast instability”, developing with an increment large in comparison with relaxation rates and the Rabi frequency, also raises the question whether the local field approximation still holds for the description of transient optical phenomena in dense media.

Excitonic effects in dense media: breakdown of intrinsic optical bistability

NASA Astrophysics Data System (ADS)

Yudson, V. I.; Reineker, P.

The steady-state nonlinear response to optical excitation is studied for a thin layer containing “two-level-atoms” (TLA). For a high density of TLAs their dipole-dipole interaction and finite excitonic bandwidth effects become important. We demonstrate that the commonly used local-field approximation ignoring excitonic band effects breaks down. Considering a system of ordered TLAs corresponding to Frenkel excitons in molecular crystals we show that excitonic effects cause an instability of spatially uniform solutions and decrease drastically the existence range of the intrinsic optical bistability of a layer. The possibility of “fast instability”, developing with an increment large in comparison with relaxation rates and the Rabi frequency, also raises the question whether the local field approximation still holds for the description of transient optical phenomena in dense media.

A likely-universal model of fracture density and scaling justified by both data and theory. Consequences for crustal hydro-mechanics

NASA Astrophysics Data System (ADS)

Davy, P.; Darcel, C.; Le Goc, R.; Bour, O.

2011-12-01

We discuss the parameters that control fracture density on the Earth. We argue that most of fracture systems are spatially organized according to two main regimes. The smallest fractures can grow independently of each others, defining a "dilute" regime controlled by nuclei occurrence rate and individual fracture growth law. Above a certain length, fractures stop growing due to mechanical interactions between fractures. For this "dense" regime, we derive the fracture density distribution by acknowledging that, statistically, fractures do not cross a larger one. This very crude rule, which expresses the inhibiting role of large fractures against smaller ones but not the reverse, actually appears be a very strong control on the eventual fracture density distribution since it results in a self-similar distribution whose exponents and density term are fully determined by the fractal dimension D and a dimensionless parameter γ that encompasses the details of fracture correlations and orientations. The range of values for D and γ appears to be extremely limited, which makes this model quite universal. This theory is supported by quantitative data on either fault or joint networks. The transition between the dilute and dense regimes occurs at about a few tenths of kilometers for faults systems, and a few meters for joints. This remarkable difference between both processes is likely due to a large-scale control (localization) of the fracture growth for faulting that does not exist for jointing. Finally, we discuss the consequences of this model on both flow and mechanical properties. In the dense regime, networks appears to be very close to a critical state.

Dense baryon matter with isospin and chiral imbalance in the framework of a NJL4 model at large Nc: Duality between chiral symmetry breaking and charged pion condensation

NASA Astrophysics Data System (ADS)

Khunjua, T. G.; Klimenko, K. G.; Zhokhov, R. N.

2018-03-01

In this paper the phase structure of dense quark matter has been investigated at zero temperature in the presence of baryon, isospin and chiral isospin chemical potentials in the framework of massless (3 +1 )-dimensional Nambu-Jona-Lasinio model with two quark flavors. It has been shown that in the large-Nc limit (Nc is the number of colors of quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation one. The key conclusion of our studies is the fact that chiral isospin chemical potential generates charged pion condensation in dense quark matter with isotopic asymmetry.

Large-eddy simulation of dense gas dispersion over a simplified urban area

NASA Astrophysics Data System (ADS)

Wingstedt, E. M. M.; Osnes, A. N.; Åkervik, E.; Eriksson, D.; Reif, B. A. Pettersson

2017-03-01

Dispersion of neutral and dense gas over a simplified urban area, comprising four cubes, has been investigated by the means of large-eddy simulations (LES). The results have been compared to wind tunnel experiments and both mean and fluctuating quantities of velocity and concentration are in very good agreement. High-quality inflow profiles are necessary to achieve physically realistic LES results. In this study, profiles matching the atmospheric boundary layer flow in the wind tunnel, are generated by means of a separate precursor simulation. Emission of dense gas dramatically alters the flow in the near source region and introduces an upstream dispersion. The resulting dispersion patterns of neutral and dense gas differ significantly, where the plume in the latter case is wider and shallower. The dense gas is highly affected by the cube array, which seems to act as a barrier, effectively deflecting the plume. This leads to higher concentrations outside of the array than inside. On the contrary, the neutral gas plume has a Gaussian-type shape, with highest concentrations along the centreline. It is found that the dense gas reduces the vertical and spanwise turbulent momentum transport and, as a consequence, the turbulence kinetic energy. The reduction coincides with the area where the gradient Richardson number exceeds its critical value, i.e. where the flow may be characterized as stably stratified. Interestingly, this region does not correspond to where the concentration of dense gas is the highest (close to the ground), as this is also where the largest velocity gradients are to be found. Instead there is a layer in the middle of the dense gas cloud where buoyancy is dynamically dominant.

Possible Climate Change Influences on Continued Reduction of Dense Fog in Southern California

NASA Astrophysics Data System (ADS)

Ladochy, S.; Witiw, M.

2010-07-01

Dense fog appears to be decreasing in many parts of the world, especially in cities. An earlier study showed that dense fog (visibility < 400 m) was disappearing in the urban southern California area as well. Using hourly data from 1948 to the present, we looked at the relationship between fog events and contributing factors in the region along with trends over time. We showed that the decrease in dense fog events could be explained mainly by declining particulate levels, Pacific SSTs, and increased urban warming. Dense fog is most prevalent along the coast and decreases rapidly inland, so the influence of the Pacific should be large. In particular, the Pacific Decadal Oscillation (PDO) and the Southern Oscillation signals can be seen in fog frequencies as well as in the contributing factors. Results show a decrease in the occurrence of dense fog at two airports in close proximity to the Pacific Ocean, LAX and LGB. Occurrence of the frequency of low visibilities at these two locations was highly correlated with the phases of the PDO. While examining data from LAX, we saw a frequency of dense fog that reached over 300 hours in 1950, but occurrence was down to zero in 1997. Since 1997, there has been a bit of a recovery with both 2008 and 2009 recording over 30 hours of dense fog each. In the present study, we continue to examine the relationships that control the frequency of dense fog in coastal southern California. To remove urban influence, we also included Vandenberg Air Force Base, located in a relatively sparsely populated area. While particulates, urban heat island and Pacific SSTs are all contributing factors, we now speculate on the direct and indirect influences of climate change on continued decreases in dense fog. Case studies of local and regional dense fog in southern California point to the importance of strong, low inversions and to a lesser contributor, Santa Ana winds. Both are associated with large-scale atmospheric circulation patterns, which have changed markedly over the period of study.

Dense-body aggregates as plastic structures supporting tension in smooth muscle cells.

PubMed

Zhang, Jie; Herrera, Ana M; Paré, Peter D; Seow, Chun Y

2010-11-01

The wall of hollow organs of vertebrates is a unique structure able to generate active tension and maintain a nearly constant passive stiffness over a large volume range. These properties are predominantly attributable to the smooth muscle cells that line the organ wall. Although smooth muscle is known to possess plasticity (i.e., the ability to adapt to large changes in cell length through structural remodeling of contractile apparatus and cytoskeleton), the detailed structural basis for the plasticity is largely unknown. Dense bodies, one of the most prominent structures in smooth muscle cells, have been regarded as the anchoring sites for actin filaments, similar to the Z-disks in striated muscle. Here, we show that the dense bodies and intermediate filaments formed cable-like structures inside airway smooth muscle cells and were able to adjust the cable length according to cell length and tension. Stretching the muscle cell bundle in the relaxed state caused the cables to straighten, indicating that these intracellular structures were connected to the extracellular matrix and could support passive tension. These plastic structures may be responsible for the ability of smooth muscle to maintain a nearly constant tensile stiffness over a large length range. The finding suggests that the structural plasticity of hollow organs may originate from the dense-body cables within the smooth muscle cells.

Human impacts on large benthic foraminifers near a densely populated area of Majuro Atoll, Marshall Islands.

PubMed

Osawa, Yoko; Fujita, Kazuhiko; Umezawa, Yu; Kayanne, Hajime; Ide, Yoichi; Nagaoka, Tatsutoshi; Miyajima, Toshihiro; Yamano, Hiroya

2010-08-01

Human impacts on sand-producing, large benthic foraminifers were investigated on ocean reef flats at the northeast Majuro Atoll, Marshall Islands, along a human population gradient. The densities of dominant foraminifers Calcarina and Amphistegina declined with distance from densely populated islands. Macrophyte composition on ocean reef flats differed between locations near sparsely or densely populated islands. Nutrient concentrations in reef-flat seawater and groundwater were high near or on densely populated islands. delta(15)N values in macroalgal tissues indicated that macroalgae in nearshore lagoons assimilate wastewater-derived nitrogen, whereas those on nearshore ocean reef flats assimilate nitrogen from other sources. These results suggest that increases in the human population result in high nutrient loading in groundwater and possibly into nearshore waters. High nutrient inputs into ambient seawater may have both direct and indirect negative effects on sand-producing foraminifers through habitat changes and/or the collapse of algal symbiosis. Copyright 2010 Elsevier Ltd. All rights reserved.

Size and space controlled hexagonal arrays of superparamagnetic iron oxide nanodots: magnetic studies and application

PubMed Central

Ghoshal, Tandra; Maity, Tuhin; Senthamaraikannan, Ramsankar; Shaw, Matthew T.; Carolan, Patrick; Holmes, Justin D.; Roy, Saibal; Morris, Michael A.

2013-01-01

Highly dense hexagonally arranged iron oxide nanodots array were fabricated using PS-b-PEO self-assembled patterns. The copolymer molecular weight, composition and choice of annealing solvent/s allows dimensional and structural control of the nanopatterns at large scale. A mechanism is proposed to create scaffolds through degradation and/or modification of cylindrical domains. A methodology based on selective metal ion inclusion and subsequent processing was used to create iron oxide nanodots array. The nanodots have uniform size and shape and their placement mimics the original self-assembled nanopatterns. For the first time these precisely defined and size selective systems of ordered nanodots allow careful investigation of magnetic properties in dimensions from 50 nm to 10 nm, which delineate the nanodots are superparamagnetic, well-isolated and size monodispersed. This diameter/spacing controlled iron oxide nanodots systems were demonstrated as a resistant mask over silicon to fabricate densely packed, identical ordered, high aspect ratio silicon nanopillars and nanowire features. PMID:24072037

Do Circumnuclear Dense Gas Disks Drive Mass Accretion onto Supermassive Black Holes?

NASA Astrophysics Data System (ADS)

Izumi, Takuma; Kawakatu, Nozomu; Kohno, Kotaro

2016-08-01

We present a positive correlation between the mass of dense molecular gas ({M}{{dense}}) of ˜100 pc scale circumnuclear disks (CNDs) and the black hole mass accretion rate ({\\dot{M}}{{BH}}) in a total of 10 Seyfert galaxies, based on data compiled from the literature and an archive (median aperture θ med = 220 pc). A typical {M}{{dense}} of CNDs is 107-8 {M}⊙ , estimated from the luminosity of the dense gas tracer, the HCN(1-0) emission line. Because dense molecular gas is the site of star formation, this correlation is virtually equivalent to the one between the nuclear star-formation rate and {\\dot{M}}{{BH}} revealed previously. Moreover, the {M}{{dense}}{--}{\\dot{M}}{{BH}} correlation was tighter for CND-scale gas than for the gas on kiloparsec or larger scales. This indicates that CNDs likely play an important role in fueling black holes, whereas greater than kiloparesec scale gas does not. To demonstrate a possible approach for studying the CND-scale accretion process with the Atacama Large Millimeter/submillimeter Array, we used a mass accretion model where angular momentum loss due to supernova explosions is vital. Based on the model prediction, we suggest that only the partial fraction of the mass accreted from the CND ({\\dot{M}}{{acc}}) is consumed as {\\dot{M}}{{BH}}. However, {\\dot{M}}{{acc}} agrees well with the total nuclear mass flow rate (I.e., {\\dot{M}}{{BH}} + outflow rate). Although these results are still tentative with large uncertainties, they support the view that star formation in CNDs can drive mass accretion onto supermassive black holes in Seyfert galaxies.

Runaway electrons as a source of impurity and reduced fusion yield in the dense plasma focus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lerner, Eric J.; Yousefi, Hamid R.

2014-10-15

Impurities produced by the vaporization of metals in the electrodes may be a major cause of reduced fusion yields in high-current dense plasma focus devices. We propose here that a major, but hitherto-overlooked, cause of such impurities is vaporization by runaway electrons during the breakdown process at the beginning of the current pulse. This process is sufficient to account for the large amount of erosion observed in many dense plasma focus devices on the anode very near to the insulator. The erosion is expected to become worse with lower pressures, typical of machines with large electrode radii, and would explainmore » the plateauing of fusion yield observed in such machines at higher peak currents. Such runaway electron vaporization can be eliminated by the proper choice of electrode material, by reducing electrode radii and thus increasing fill gas pressure, or by using pre-ionization to eliminate the large fields that create runaway electrons. If these steps are combined with monolithic electrodes to eliminate arcing erosion, large reductions in impurities and large increases in fusion yield may be obtained, as the I{sup 4} scaling is extended to higher currents.« less

Laser Heating in a Dense Plasma Focus.

DTIC Science & Technology

The report is divided in two parts. In the first part an account is given of the measurement of the momentum distribution of the deuterons ejected from a dense plasma focus . The results show the existence of a pronounced non-Maxwellian distribution and a small population of deuterons accelerated to the voltage of the condenser bank. In the second part theoretical calculation of laser heating establish the presence of large density gradient which probably accounts for the large currents detected in such plasmas. (Author)

Deciphering landslide behavior using large-scale flume experiments

USGS Publications Warehouse

Reid, Mark E.; Iverson, Richard M.; Iverson, Neal R.; LaHusen, Richard G.; Brien, Dianne L.; Logan, Matthew

2008-01-01

Landslides can be triggered by a variety of hydrologic events and they can exhibit a wide range of movement dynamics. Effective prediction requires understanding these diverse behaviors. Precise evaluation in the field is difficult; as an alternative we performed a series of landslide initiation experiments in the large-scale, USGS debris-flow flume. We systematically investigated the effects of three different hydrologic triggering mechanisms, including groundwater exfiltration from bedrock, prolonged rainfall infiltration, and intense bursts of rain. We also examined the effects of initial soil porosity (loose or dense) relative to the soil’s critical-state porosity. Results show that all three hydrologic mechanisms can instigate landsliding, but water pathways, sensor response patterns, and times to failure differ. Initial soil porosity has a profound influence on landslide movement behavior. Experiments using loose soil show rapid soil contraction during failure, with elevated pore pressures liquefying the sediment and creating fast-moving debris flows. In contrast, dense soil dilated upon shearing, resulting in slow, gradual, and episodic motion. These results have fundamental implications for forecasting landslide behavior and developing effective warning systems.

Overlapping communities from dense disjoint and high total degree clusters

NASA Astrophysics Data System (ADS)

Zhang, Hongli; Gao, Yang; Zhang, Yue

2018-04-01

Community plays an important role in the field of sociology, biology and especially in domains of computer science, where systems are often represented as networks. And community detection is of great importance in the domains. A community is a dense subgraph of the whole graph with more links between its members than between its members to the outside nodes, and nodes in the same community probably share common properties or play similar roles in the graph. Communities overlap when nodes in a graph belong to multiple communities. A vast variety of overlapping community detection methods have been proposed in the literature, and the local expansion method is one of the most successful techniques dealing with large networks. The paper presents a density-based seeding method, in which dense disjoint local clusters are searched and selected as seeds. The proposed method selects a seed by the total degree and density of local clusters utilizing merely local structures of the network. Furthermore, this paper proposes a novel community refining phase via minimizing the conductance of each community, through which the quality of identified communities is largely improved in linear time. Experimental results in synthetic networks show that the proposed seeding method outperforms other seeding methods in the state of the art and the proposed refining method largely enhances the quality of the identified communities. Experimental results in real graphs with ground-truth communities show that the proposed approach outperforms other state of the art overlapping community detection algorithms, in particular, it is more than two orders of magnitude faster than the existing global algorithms with higher quality, and it obtains much more accurate community structure than the current local algorithms without any priori information.

Toward Gas Chemistry in Low Metallicity Starburst Galaxies

NASA Astrophysics Data System (ADS)

Meier, David S.; Anderson, Crystal N.; Turner, Jean; Ott, Juergen; Beck, Sara C.

2017-01-01

Dense gas, which is intimately connected with star formation, is key to understanding star formation. Though challenging to study, dense gas in low metallicity starbursts is important given these system's often extreme star formation and their potential implications for high redshift analogs. High spatial resolution (~50 pc) ALMA observations of several key probes of gas chemistry, including HCN(1-0), HCO+(1-0), CS(2-1), CCH(1-0;3/2-1/2) and SiO(2-1), towards the nearby super star-cluster (SSC) forming, sub-solar metallicity galaxy NGC 5253 are discussed. Dense gas is observed to be extended well beyond the current compact starburst, reaching into the apparently infalling molecular streamer. The faintness of HCN, the standard dense gas tracer, is extreme both in an absolute sense relative to high metallicity starbursts of a similar intensity and in a relative sense, with the HCO+/HCN ratio being one of the most elevated observed. UV-irradiated molecular gas, traced by CCH, is also extended over the mapped region, not being strongly correlated with the SSC. Despite the accretion of molecular gas from the halo and the intense burst of star formation, chemical signatures of shocked gas, traced by SiO (and HNCO), are not obvious. By placing NGC 5253 in context with other local starbursts, like 30 Doradus in the Large Magellanic Clouds and the high metallicity proto-typical starburst NGC 253, it is suggested that a combination of gas excitation and abundance changes associated with the sub solar metallicity may explain these anomalous dense gas properties.

A new numerical benchmark for variably saturated variable-density flow and transport in porous media

NASA Astrophysics Data System (ADS)

Guevara, Carlos; Graf, Thomas

2016-04-01

In subsurface hydrological systems, spatial and temporal variations in solute concentration and/or temperature may affect fluid density and viscosity. These variations could lead to potentially unstable situations, in which a dense fluid overlies a less dense fluid. These situations could produce instabilities that appear as dense plume fingers migrating downwards counteracted by vertical upwards flow of freshwater (Simmons et al., Transp. Porous Medium, 2002). As a result of unstable variable-density flow, solute transport rates are increased over large distances and times as compared to constant-density flow. The numerical simulation of variable-density flow in saturated and unsaturated media requires corresponding benchmark problems against which a computer model is validated (Diersch and Kolditz, Adv. Water Resour, 2002). Recorded data from a laboratory-scale experiment of variable-density flow and solute transport in saturated and unsaturated porous media (Simmons et al., Transp. Porous Medium, 2002) is used to define a new numerical benchmark. The HydroGeoSphere code (Therrien et al., 2004) coupled with PEST (www.pesthomepage.org) are used to obtain an optimized parameter set capable of adequately representing the data set by Simmons et al., (2002). Fingering in the numerical model is triggered using random hydraulic conductivity fields. Due to the inherent randomness, a large number of simulations were conducted in this study. The optimized benchmark model adequately predicts the plume behavior and the fate of solutes. This benchmark is useful for model verification of variable-density flow problems in saturated and/or unsaturated media.

Deletion of a target gene in Indica rice via CRISPR/Cas9.

PubMed

Wang, Ying; Geng, Lizhao; Yuan, Menglong; Wei, Juan; Jin, Chen; Li, Min; Yu, Kun; Zhang, Ya; Jin, Huaibing; Wang, Eric; Chai, Zhijian; Fu, Xiangdong; Li, Xianggan

2017-08-01

Using CRISPR/Cas9, we successfully deleted large fragments of the yield-related gene DENSE AND ERECT PANICLE1 in Indica rice at relatively high frequency and generated gain-of-function dep1 mutants. CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 is a rapidly developing technology used to produce gene-specific modifications in both mammalian and plant systems. Most CRISPR-induced modifications in plants reported to date have been small insertions or deletions. Few large target gene deletions have thus far been reported, especially for Indica rice. In this study, we designed multiple CRISPR sgRNAs and successfully deleted DNA fragments in the gene DENSE AND ERECT PANICLE1 (DEP1) in the elite Indica rice line IR58025B. We achieved deletion frequencies of up to 21% for a 430 bp target and 9% for a 10 kb target among T0 events. Constructs with four sgRNAs did not generate higher full-length deletion frequencies than constructs with two sgRNAs. The multiple mutagenesis frequency reached 93% for four targets, and the homozygous mutation frequency reached 21% at the T0 stage. Important yield-related trait characteristics, such as dense and erect panicles and reduced plant height, were observed in dep1 homozygous T0 mutant plants produced by CRISPR/Cas9. Therefore, we successfully obtained deletions in DEP1 in the Indica background using the CRISPR/Cas9 editing tool at relatively high frequency.

Analysis of foliage effects on mobile propagation in dense urban environments

NASA Astrophysics Data System (ADS)

Bronshtein, Alexander; Mazar, Reuven; Lu, I.-Tai

2000-07-01

Attempts to reduce the interference level and to increase the spectral efficiency of cellular radio communication systems operating in dense urban and suburban areas lead to the microcellular approach with a consequent requirement to lower antenna heights. In large metropolitan areas having high buildings this requirement causes a situation where the transmitting and receiving antennas are both located below the rooftops, and the city street acts as a type of a waveguiding channel for the propagating signal. In this work, the city street is modeled as a random multislit waveguide with randomly distributed regions of foliage parallel to the building boundaries. The statistical propagation characteristics are expressed in terms of multiple ray-fields approaching the observer. Algorithms for predicting the path-loss along the waveguide and for computing the transverse field structure are presented.

Dilute and dense axion stars

NASA Astrophysics Data System (ADS)

Visinelli, Luca; Baum, Sebastian; Redondo, Javier; Freese, Katherine; Wilczek, Frank

2018-02-01

Axion stars are hypothetical objects formed of axions, obtained as localized and coherently oscillating solutions to their classical equation of motion. Depending on the value of the field amplitude at the core |θ0 | ≡ | θ (r = 0) |, the equilibrium of the system arises from the balance of the kinetic pressure and either self-gravity or axion self-interactions. Starting from a general relativistic framework, we obtain the set of equations describing the configuration of the axion star, which we solve as a function of |θ0 |. For small |θ0 | ≲ 1, we reproduce results previously obtained in the literature, and we provide arguments for the stability of such configurations in terms of first principles. We compare qualitative analytical results with a numerical calculation. For large amplitudes |θ0 | ≳ 1, the axion field probes the full non-harmonic QCD chiral potential and the axion star enters the dense branch. Our numerical solutions show that in this latter regime the axions are relativistic, and that one should not use a single frequency approximation, as previously applied in the literature. We employ a multi-harmonic expansion to solve the relativistic equation for the axion field in the star, and demonstrate that higher modes cannot be neglected in the dense regime. We interpret the solutions in the dense regime as pseudo-breathers, and show that the life-time of such configurations is much smaller than any cosmological time scale.

Carbon chemistry in dense molecular clouds: Theory and observational constraints

NASA Technical Reports Server (NTRS)

Blake, Geoffrey A.

1990-01-01

For the most part, gas phase models of the chemistry of dense molecular clouds predict the abundances of simple species rather well. However, for larger molecules and even for small systems rich in carbon these models often fail spectacularly. Researchers present a brief review of the basic assumptions and results of large scale modeling of the carbon chemistry in dense molecular clouds. Particular attention is to the influence of the gas phase C/O ratio in molecular clouds, and the likely role grains play in maintaining this ratio as clouds evolve from initially diffuse objects to denser cores with associated stellar and planetary formation. Recent spectral line surveys at centimeter and millimeter wavelengths along with selected observations in the submillimeter have now produced an accurate inventory of the gas phase carbon budget in several different types of molecular clouds, though gaps in our knowledge clearly remain. The constraints these observations place on theoretical models of interstellar chemistry can be used to gain insights into why the models fail, and show also which neglected processes must be included in more complete analyses. Looking toward the future, larger molecules are especially difficult to study both experimentally and theoretically in such dense, cold regions, and some new methods are therefore outlined which may ultimately push the detectability of small carbon chains and rings to much heavier species.

A Sector Capacity Assessment Method Based on Airspace Utilization Efficiency

NASA Astrophysics Data System (ADS)

Zhang, Jianping; Zhang, Ping; Li, Zhen; Zou, Xiang

2018-02-01

Sector capacity is one of the core factors affecting the safety and the efficiency of the air traffic system. Most of previous sector capacity assessment methods only considered the air traffic controller’s (ATCO’s) workload. These methods are not only limited which only concern about the safety, but also not accurate enough. In this paper, we employ the integrated quantitative index system proposed in one of our previous literatures. We use the principal component analysis (PCA) to find out the principal indicators among the indicators so as to calculate the airspace utilization efficiency. In addition, we use a series of fitting functions to test and define the correlation between the dense of air traffic flow and the airspace utilization efficiency. The sector capacity is then decided as the value of the dense of air traffic flow corresponding to the maximum airspace utilization efficiency. We also use the same series of fitting functions to test the correlation between the dese of air traffic flow and the ATCOs’ workload. We examine our method with a large amount of empirical operating data of Chengdu Controlling Center and obtain a reliable sector capacity value. Experiment results also show superiority of our method against those only consider the ATCO’s workload in terms of better correlation between the airspace utilization efficiency and the dense of air traffic flow.

Thresholds in the response of free-floating plant abundance to variation in hydraulic connectivity, nutrients, and macrophyte abundance in a large floodplain river

USGS Publications Warehouse

Giblin, Shawn M.; Houser, Jeffrey N.; Sullivan, John F.; Langrehr, H.A.; Rogala, James T.; Campbell, Benjamin D.

2014-01-01

Duckweed and other free-floating plants (FFP) can form dense surface mats that affect ecosystem condition and processes, and can impair public use of aquatic resources. FFP obtain their nutrients from the water column, and the formation of dense FFP mats can be a consequence and indicator of river eutrophication. We conducted two complementary surveys of diverse aquatic areas of the Upper Mississippi River as an in situ approach for estimating thresholds in the response of FFP abundance to nutrient concentration and physical conditions in a large, floodplain river. Local regression analysis was used to estimate thresholds in the relations between FFP abundance and phosphorus (P) concentration (0.167 mg l−1L), nitrogen (N) concentration (0.808 mg l−1), water velocity (0.095 m s−1), and aquatic macrophyte abundance (65 % cover). FFP tissue concentrations suggested P limitation was more likely in spring, N limitation was more likely in late summer, and N limitation was most likely in backwaters with minimal hydraulic connection to the channel. The thresholds estimated here, along with observed patterns in nutrient limitation, provide river scientists and managers with criteria to consider when attempting to modify FFP abundance in off-channel areas of large river systems.

An Intelligent Surveillance Platform for Large Metropolitan Areas with Dense Sensor Deployment

PubMed Central

Fernández, Jorge; Calavia, Lorena; Baladrón, Carlos; Aguiar, Javier M.; Carro, Belén; Sánchez-Esguevillas, Antonio; Alonso-López, Jesus A.; Smilansky, Zeev

2013-01-01

This paper presents an intelligent surveillance platform based on the usage of large numbers of inexpensive sensors designed and developed inside the European Eureka Celtic project HuSIMS. With the aim of maximizing the number of deployable units while keeping monetary and resource/bandwidth costs at a minimum, the surveillance platform is based on the usage of inexpensive visual sensors which apply efficient motion detection and tracking algorithms to transform the video signal in a set of motion parameters. In order to automate the analysis of the myriad of data streams generated by the visual sensors, the platform's control center includes an alarm detection engine which comprises three components applying three different Artificial Intelligence strategies in parallel. These strategies are generic, domain-independent approaches which are able to operate in several domains (traffic surveillance, vandalism prevention, perimeter security, etc.). The architecture is completed with a versatile communication network which facilitates data collection from the visual sensors and alarm and video stream distribution towards the emergency teams. The resulting surveillance system is extremely suitable for its deployment in metropolitan areas, smart cities, and large facilities, mainly because cheap visual sensors and autonomous alarm detection facilitate dense sensor network deployments for wide and detailed coverage. PMID:23748169

Risk assessment of sewer condition using artificial intelligence tools: application to the SANEST sewer system.

PubMed

Sousa, V; Matos, J P; Almeida, N; Saldanha Matos, J

2014-01-01

Operation, maintenance and rehabilitation comprise the main concerns of wastewater infrastructure asset management. Given the nature of the service provided by a wastewater system and the characteristics of the supporting infrastructure, technical issues are relevant to support asset management decisions. In particular, in densely urbanized areas served by large, complex and aging sewer networks, the sustainability of the infrastructures largely depends on the implementation of an efficient asset management system. The efficiency of such a system may be enhanced with technical decision support tools. This paper describes the role of artificial intelligence tools such as artificial neural networks and support vector machines for assisting the planning of operation and maintenance activities of wastewater infrastructures. A case study of the application of this type of tool to the wastewater infrastructures of Sistema de Saneamento da Costa do Estoril is presented.

Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: An integrated modeling approach

NASA Astrophysics Data System (ADS)

Hassan, S. M. Tanvir; Lubczynski, Maciek W.; Niswonger, Richard G.; Su, Zhongbo

2014-09-01

The structural and hydrological complexity of hard rock systems (HRSs) affects dynamics of surface-groundwater interactions. These complexities are not well described or understood by hydrogeologists because simplified analyses typically are used to study HRSs. A transient, integrated hydrologic model (IHM) GSFLOW (Groundwater and Surface water FLOW) was calibrated and post-audited using 18 years of daily groundwater head and stream discharge data to evaluate the surface-groundwater interactions in semi-arid, ∼80 km2 granitic Sardon hilly catchment in Spain characterized by shallow water table conditions, relatively low storage, dense drainage networks and frequent, high intensity rainfall. The following hydrological observations for the Sardon Catchment, and more generally for HRSs were made: (i) significant bi-directional vertical flows occur between surface water and groundwater throughout the HRSs; (ii) relatively large groundwater recharge represents 16% of precipitation (P, 562 mm.y-1) and large groundwater exfiltration (∼11% of P) results in short groundwater flow paths due to a dense network of streams, low permeability and hilly topographic relief; deep, long groundwater flow paths constitute a smaller component of the water budget (∼1% of P); quite high groundwater evapotranspiration (∼5% of P and ∼7% of total evapotranspiration); low permeability and shallow soils are the main reasons for relatively large components of Hortonian flow and interflow (15% and 11% of P, respectively); (iii) the majority of drainage from the catchment leaves as surface water; (iv) declining 18 years trend (4.44 mm.y-1) of groundwater storage; and (v) large spatio-temporal variability of water fluxes. This IHM study of HRSs provides greater understanding of these relatively unknown hydrologic systems that are widespread throughout the world and are important for water resources in many regions.

Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach

USGS Publications Warehouse

Hassan, S.M. Tanvir; Lubczynski, Maciek W.; Niswonger, Richard G.; Zhongbo, Su

2014-01-01

The structural and hydrological complexity of hard rock systems (HRSs) affects dynamics of surface–groundwater interactions. These complexities are not well described or understood by hydrogeologists because simplified analyses typically are used to study HRSs. A transient, integrated hydrologic model (IHM) GSFLOW (Groundwater and Surface water FLOW) was calibrated and post-audited using 18 years of daily groundwater head and stream discharge data to evaluate the surface–groundwater interactions in semi-arid, ∼80 km2 granitic Sardon hilly catchment in Spain characterized by shallow water table conditions, relatively low storage, dense drainage networks and frequent, high intensity rainfall. The following hydrological observations for the Sardon Catchment, and more generally for HRSs were made: (i) significant bi-directional vertical flows occur between surface water and groundwater throughout the HRSs; (ii) relatively large groundwater recharge represents 16% of precipitation (P, 562 mm.y−1) and large groundwater exfiltration (∼11% of P) results in short groundwater flow paths due to a dense network of streams, low permeability and hilly topographic relief; deep, long groundwater flow paths constitute a smaller component of the water budget (∼1% of P); quite high groundwater evapotranspiration (∼5% of P and ∼7% of total evapotranspiration); low permeability and shallow soils are the main reasons for relatively large components of Hortonian flow and interflow (15% and 11% of P, respectively); (iii) the majority of drainage from the catchment leaves as surface water; (iv) declining 18 years trend (4.44 mm.y−1) of groundwater storage; and (v) large spatio-temporal variability of water fluxes. This IHM study of HRSs provides greater understanding of these relatively unknown hydrologic systems that are widespread throughout the world and are important for water resources in many regions.

Point-Cloud Compression for Vehicle-Based Mobile Mapping Systems Using Portable Network Graphics

NASA Astrophysics Data System (ADS)

Kohira, K.; Masuda, H.

2017-09-01

A mobile mapping system is effective for capturing dense point-clouds of roads and roadside objects Point-clouds of urban areas, residential areas, and arterial roads are useful for maintenance of infrastructure, map creation, and automatic driving. However, the data size of point-clouds measured in large areas is enormously large. A large storage capacity is required to store such point-clouds, and heavy loads will be taken on network if point-clouds are transferred through the network. Therefore, it is desirable to reduce data sizes of point-clouds without deterioration of quality. In this research, we propose a novel point-cloud compression method for vehicle-based mobile mapping systems. In our compression method, point-clouds are mapped onto 2D pixels using GPS time and the parameters of the laser scanner. Then, the images are encoded in the Portable Networking Graphics (PNG) format and compressed using the PNG algorithm. In our experiments, our method could efficiently compress point-clouds without deteriorating the quality.

Turbulence Modulation and Dense-Spray Structure

DTIC Science & Technology

1988-08-01

system ............................................. 10 6 Particle size distribution (dp = 0.5 mm) .................................... 13 7 Particle size...54 27 Sketch of the pressurized test apparatus .................................... 55 28 Sketch of the double-pulse holocamera system ...58 29 Sketch of the hologram reconstruction system ............................ 59 30 Typical hologram reconstruction in the dense

Contact-aware simulations of particulate Stokesian suspensions

NASA Astrophysics Data System (ADS)

Lu, Libin; Rahimian, Abtin; Zorin, Denis

2017-10-01

We present an efficient, accurate, and robust method for simulation of dense suspensions of deformable and rigid particles immersed in Stokesian fluid in two dimensions. We use a well-established boundary integral formulation for the problem as the foundation of our approach. This type of formulation, with a high-order spatial discretization and an implicit and adaptive time discretization, have been shown to be able to handle complex interactions between particles with high accuracy. Yet, for dense suspensions, very small time-steps or expensive implicit solves as well as a large number of discretization points are required to avoid non-physical contact and intersections between particles, leading to infinite forces and numerical instability. Our method maintains the accuracy of previous methods at a significantly lower cost for dense suspensions. The key idea is to ensure interference-free configuration by introducing explicit contact constraints into the system. While such constraints are unnecessary in the formulation, in the discrete form of the problem, they make it possible to eliminate catastrophic loss of accuracy by preventing contact explicitly. Introducing contact constraints results in a significant increase in stable time-step size for explicit time-stepping, and a reduction in the number of points adequate for stability.

PHENIX Measurements of Heavy Flavor in Small Systems

NASA Astrophysics Data System (ADS)

Lebedev, Alexandre

2018-01-01

The study of heavy flavor production in proton-nucleus and nucleus-nucleus collisions is a sensitive probe of the hot and dense matter created in such collisions. Installation of silicon vertex detectors in the PHENIX experiment, and increased performance of the BNL RHIC collider allowed collection of large amount of data on heavy flavor production in small colliding systems. In this talk we will present recent PHENIX results on open heavy flavor and quarkonia production in p+p, p+A, d+A, and He3+A colliding systems in a broad rapidity range, and discuss how these measurements help us to better understand all stages of nuclear collisions at high energy.

High performance architecture design for large scale fibre-optic sensor arrays using distributed EDFAs and hybrid TDM/DWDM

NASA Astrophysics Data System (ADS)

Liao, Yi; Austin, Ed; Nash, Philip J.; Kingsley, Stuart A.; Richardson, David J.

2013-09-01

A distributed amplified dense wavelength division multiplexing (DWDM) array architecture is presented for interferometric fibre-optic sensor array systems. This architecture employs a distributed erbium-doped fibre amplifier (EDFA) scheme to decrease the array insertion loss, and employs time division multiplexing (TDM) at each wavelength to increase the number of sensors that can be supported. The first experimental demonstration of this system is reported including results which show the potential for multiplexing and interrogating up to 4096 sensors using a single telemetry fibre pair with good system performance. The number can be increased to 8192 by using dual pump sources.

Prebiotic chemical evolution in the astrophysical context.

PubMed

Ziurys, L M; Adande, G R; Edwards, J L; Schmidt, D R; Halfen, D T; Woolf, N J

2015-06-01

An ever increasing amount of molecular material is being discovered in the interstellar medium, associated with the birth and death of stars and planetary systems. Radio and millimeter-wave astronomical observations, made possible by high-resolution laboratory spectroscopy, uniquely trace the history of gas-phase molecules with biogenic elements. Using a combination of both disciplines, the full extent of the cycling of molecular matter, from circumstellar ejecta of dying stars - objects which expel large amounts of carbon - to nascent solar systems, has been investigated. Such stellar ejecta have been found to exhibit a rich and varied chemical content. Observations demonstrate that this molecular material is passed onto planetary nebulae, the final phase of stellar evolution. Here the star sheds almost its entire original mass, becoming an ultraviolet-emitting white dwarf. Molecules such as H2CO, HCN, HCO(+), and CCH are present in significant concentrations across the entire age span of such nebulae. These data suggest that gas-phase polyatomic, carbon-containing molecules survive the planetary nebula phase and subsequently are transported into the interstellar medium, seeding the chemistry of diffuse and then dense clouds. The extent of the chemical complexity in dense clouds is unknown, hindered by the high spectral line density. Organic species such as acetamide and methyl amine are present in such objects, and NH2CHO has a wide Galactic distribution. However, organophosphorus compounds have not yet been detected in dense clouds. Based on carbon and nitrogen isotope ratios, molecular material from the ISM appears to become incorporated into solar system planetesimals. It is therefore likely that interstellar synthesis influences prebiotic chemistry on planet surfaces.

Embedded binaries and their dense cores

NASA Astrophysics Data System (ADS)

Sadavoy, Sarah I.; Stahler, Steven W.

2017-08-01

We explore the relationship between young, embedded binaries and their parent cores, using observations within the Perseus Molecular Cloud. We combine recently published Very Large Array observations of young stars with core properties obtained from Submillimetre Common-User Bolometer Array 2 observations at 850 μm. Most embedded binary systems are found towards the centres of their parent cores, although several systems have components closer to the core edge. Wide binaries, defined as those systems with physical separations greater than 500 au, show a tendency to be aligned with the long axes of their parent cores, whereas tight binaries show no preferred orientation. We test a number of simple, evolutionary models to account for the observed populations of Class 0 and I sources, both single and binary. In the model that best explains the observations, all stars form initially as wide binaries. These binaries either break up into separate stars or else shrink into tighter orbits. Under the assumption that both stars remain embedded following binary break-up, we find a total star formation rate of 168 Myr-1. Alternatively, one star may be ejected from the dense core due to binary break-up. This latter assumption results in a star formation rate of 247 Myr-1. Both production rates are in satisfactory agreement with current estimates from other studies of Perseus. Future observations should be able to distinguish between these two possibilities. If our model continues to provide a good fit to other star-forming regions, then the mass fraction of dense cores that becomes stars is double what is currently believed.

Model Order Reduction Algorithm for Estimating the Absorption Spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Beeumen, Roel; Williams-Young, David B.; Kasper, Joseph M.

The ab initio description of the spectral interior of the absorption spectrum poses both a theoretical and computational challenge for modern electronic structure theory. Due to the often spectrally dense character of this domain in the quantum propagator’s eigenspectrum for medium-to-large sized systems, traditional approaches based on the partial diagonalization of the propagator often encounter oscillatory and stagnating convergence. Electronic structure methods which solve the molecular response problem through the solution of spectrally shifted linear systems, such as the complex polarization propagator, offer an alternative approach which is agnostic to the underlying spectral density or domain location. This generality comesmore » at a seemingly high computational cost associated with solving a large linear system for each spectral shift in some discretization of the spectral domain of interest. In this work, we present a novel, adaptive solution to this high computational overhead based on model order reduction techniques via interpolation. Model order reduction reduces the computational complexity of mathematical models and is ubiquitous in the simulation of dynamical systems and control theory. The efficiency and effectiveness of the proposed algorithm in the ab initio prediction of X-ray absorption spectra is demonstrated using a test set of challenging water clusters which are spectrally dense in the neighborhood of the oxygen K-edge. On the basis of a single, user defined tolerance we automatically determine the order of the reduced models and approximate the absorption spectrum up to the given tolerance. We also illustrate that, for the systems studied, the automatically determined model order increases logarithmically with the problem dimension, compared to a linear increase of the number of eigenvalues within the energy window. Furthermore, we observed that the computational cost of the proposed algorithm only scales quadratically with respect to the problem dimension.« less

A simple 2D biofilm model yields a variety of morphological features.

PubMed

Hermanowicz, S W

2001-01-01

A two-dimensional biofilm model was developed based on the concept of cellular automata. Three simple, generic processes were included in the model: cell growth, internal and external mass transport and cell detachment (erosion). The model generated a diverse range of biofilm morphologies (from dense layers to open, mushroom-like forms) similar to those observed in real biofilm systems. Bulk nutrient concentration and external mass transfer resistance had a large influence on the biofilm structure.

Association/Dissociation Processes in Dense Gases.

DTIC Science & Technology

1985-08-16

temperature 0 and generally lies 1 0 ke below the dissociation limit (taken as zero energy). The central block E of highly excited " bound levels is...approximate solution of (1.1) with general V(R) "* a large body of literature (see ref. 7) exists on various schemes based on Green’s function,8...be obtained for general mass systems provided the new basic expression introduced here - for RAD(t) is adopted. A The microscopic basis of the

Annual Technical Report, Materials Research Laboratory July 1, 1979 - June 30, 1980.

DTIC Science & Technology

1980-06-30

dense, highly degenerate, transient electron hole systems in PbTe, nSb, a H9 Cd Te. In these experiments an intense ultrashort pulse generated a high...J. Gerritsen, J. Appl. Phys. 51 (1980), 1603. "Generation of Ultrashort Pulses in Synchronous Pumping of Near-Millimeter Wave Lasers ," A. V. Nurmikko...deformation caused by a relatively large amplitude stress pulse . . The relationship between strain rate, stress, and temperature has been examined for bcc

Earth Observations taken by the Expedition 18 Crew

NASA Image and Video Library

2008-10-24

ISS018-E-005058 (24 Oct. 2008) --- Southern California's coastline, from southern Los Angeles to Tijuana in Mexico, a distance of about 225 kilometers, is featured in this image photographed by an Expedition 18 crewmember on the International Space Station. Port facilities of Los Angeles Harbor give much detail to the coastline at the north end and arcuate San Diego Bay is highly recognizable at the south end (right bottom). The image includes much of one of the most densely populated parts of the USA, with approximately 20 million people within the parts of five counties shown here. The dense urban areas appear gray, with the largest conurbation in the north of the view, in the region Long Beach--Los Angeles--San Bernardino. A smaller zone appears around San Diego--Tijuana in the south. Major highways with their associated strip development snake through these dense urban areas. The geography and geomorphology of Southern California is defined by long linear features that are surface traces of large transform faults. These faults, including the Elsinore fault and San Jacinto fault seen here, are generally considered part of the San Andreas system, and make up the broad zone comprising the tectonic plate boundary between North America to the east and the Pacific plate to the west. The Elsinore fault marks the steep eastern scarp of the Santa Ana Mountains, as well as the precipitation boundary between the wetter mountains and the drier deserts to the east. The rainfall difference is reflected in the darker appearance (more vegetation) of the mountains and coastal regions. Inland of the mountains, climates are far drier, and the natural vegetation is scrubby and much less dense which allows brown and yellow soils to show through. However, the entire region is arid; water management is a critical issue for the large urban areas of the state. Several reservoirs that are visible east of the Santa Ana Mountains provide water for both cities and agriculture in southern California.

Experiments on the Expansion of a Dense Plasma into a Background Magnetoplasma

NASA Astrophysics Data System (ADS)

Gekelman, Walter; Vanzeeland, Mike; Vincena, Steve; Pribyl, Pat

2003-10-01

There are many situations, which occur in space (coronal mass ejections, or are man-made (upper atmospheric detonations) as well as the initial stages of a supernovae, in which a dense plasma expands into a background magnetized plasma, that can support Alfvèn waves. The upgraded LArge Plasma Device (LAPD) is a machine, at UCLA, in which Alfvèn wave propagation in homogeneous and inhomogeneous plasmas has been studied. We describe a series of experiments,which involve the expansion of a dense (initially, n_laser-plasma/n_0≫1) laser-produced plasma into an ambient highly magnetized background plasma capable of supporting Alfvèn waves will be presented. The 150 MW laser is pulsed at the same 1 Hz repetition rate as the plasma in a highly reproducible experiment. The interaction results in the production of intense shear Alfvèn waves, as well as large density perturbations. The waves propagate away from the target and are observed to become plasma column resonances. In the initial phase the background magnetic field is expelled from a plasma bubble. Currents in the main body of the plasma are generated to neutralize the positively charged bubble. The current system which results, becomes that of a spectrum of shear Alfvèn waves. Spatial patterns of the wave magnetic fields waves are measured at over 10^4 locations. As the dense plasma expands across the magnetic field it seeds the column with shear waves. Most of the Alfvèn wave energy is in shear waves, which become field line resonances after a machine transit time. The interplay between waves, currents, inductive electric fields and space charge is analyzed in great detail. Dramatic movies of the measured wave fields and their associated currents will be presented. Work supported by ONR, and DOE /NSF.

Turbulent dusty boundary layer in an ANFO surface-burst explosion

NASA Astrophysics Data System (ADS)

Kuhl, A. L.; Ferguson, R. E.; Chien, K. Y.; Collins, J. P.

1992-01-01

This paper describes the results of numerical simulations of the dusty, turbulent boundary layer created by a surface burst explosion. The blast wave was generated by the detonation of a 600-T hemisphere of ANFO, similar to those used in large-scale field tests. The surface was assumed to be ideally noncratering but contained an initial loose layer of dust. The dust-air mixture in this fluidized bed was modeled as a dense gas (i.e., an equilibrium model, valid for very small-diameter dust particles). The evolution of the flow was calculated by a high-order Godunov code that solves the nonsteady conservation laws. Shock interactions with dense layer generated vorticity near the wall, a result that is similar to viscous, no-slip effects found in clean flows. The resulting wall shear layer was unstable, and rolled up into large-scale rotational structures. These structures entrained dense material from the wall layer and created a chaotically striated flow. The boundary layer grew due to merging of the large-scale structures and due to local entrainment of the dense material from the fluidized bed. The chaotic flow was averaged along similarity lines (i.e., lines of constant values of x = r/Rs and y = z/Rs where R(sub s) = ct(exp alpha)) to establish the mean-flow profiles and the r.m.s. fluctuating-flow profiles of the boundary layer.

Weak synchronization and large-scale collective oscillation in dense bacterial suspensions

NASA Astrophysics Data System (ADS)

Wu, Yilin

Collective oscillatory behavior is ubiquitous in nature and it plays a vital role in many biological processes. Collective oscillations in biological multicellular systems often arise from coupling mediated by diffusive chemicals, by electrochemical mechanisms, or by biomechanical interaction between cells and their physical environment. In these examples, the phase of some oscillatory intracellular degree of freedom is synchronized. Here, in contrast, we discovered a unique 'weak synchronization' mechanism that does not require long-range coupling, nor even inherent oscillation of individual cells: We found that millions of motile cells in dense bacterial suspensions can self-organize into highly robust collective oscillatory motion, while individuals move in an erratic manner. Over large spatial scales we found that the phase of the oscillations is in fact organized into a centimeter scale traveling wave. We present a model of noisy self-propelled particles with strictly local interactions that accounts faithfully for our observations. These findings expand our knowledge of biological self-organization and reveal a new type of long-range order in active matter systems. The mechanism of collective oscillation uncovered here may inspire new strategies to control the self-organization of active matter and swarming robots. This work is supported by funding from CUHK Direct research Grants (4053019, 4053079, 4053130), the Research Grants Council of HKSAR (RGC Ref. No. CUHK 409713), and from the National Natural Science Foundation of China (NSFC 21473152).

Sleipner vest CO{sub 2} disposal, CO{sub 2} injection into a shallow underground aquifer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baklid, A.; Korbol, R.; Owren, G.

1996-12-31

This paper describes the problem of disposing large amounts of CO{sub 2} into a shallow underground aquifer from an offshore location in the North Sea. The solutions presented is an alternative for CO{sub 2} emitting industries in addressing the growing concern for the environmental impact from such activities. The topside injection facilities, the well and reservoir aspects are discussed as well as the considerations made during establishing the design basis and the solutions chosen. The CO{sub 2} injection issues in this project differs from industry practice in that the CO{sub 2} is wet and contaminated with methane, and further, becausemore » of the shallow depth, the total pressure resistance in the system is not sufficient for the CO{sub 2} to naturally stay in the dense phase region. To allow for safe and cost effective handling of the CO{sub 2}, it was necessary to develop an injection system that gave a constant back pressure from the well corresponding to the output pressure from the compressor, and being independent of the injection rate. This is accomplished by selecting a high injectivity sand formation, completing the well with a large bore, and regulating the dense phase CO{sub 2} temperature and thus the density of the fluid in order to account for the variations in back pressure from the well.« less

Super-resolving random-Gaussian apodized photon sieve.

PubMed

Sabatyan, Arash; Roshaninejad, Parisa

2012-09-10

A novel apodized photon sieve is presented in which random dense Gaussian distribution is implemented to modulate the pinhole density in each zone. The random distribution in dense Gaussian distribution causes intrazone discontinuities. Also, the dense Gaussian distribution generates a substantial number of pinholes in order to form a large degree of overlap between the holes in a few innermost zones of the photon sieve; thereby, clear zones are formed. The role of the discontinuities on the focusing properties of the photon sieve is examined as well. Analysis shows that secondary maxima have evidently been suppressed, transmission has increased enormously, and the central maxima width is approximately unchanged in comparison to the dense Gaussian distribution. Theoretical results have been completely verified by experiment.

Dynamical theory of dense groups of galaxies

NASA Technical Reports Server (NTRS)

Mamon, Gary A.

1990-01-01

It is well known that galaxies associate in groups and clusters. Perhaps 40% of all galaxies are found in groups of 4 to 20 galaxies (e.g., Tully 1987). Although most groups appear to be so loose that the galaxy interactions within them ought to be insignificant, the apparently densest groups, known as compact groups appear so dense when seen in projection onto the plane of the sky that their members often overlap. These groups thus appear as dense as the cores of rich clusters. The most popular catalog of compact groups, compiled by Hickson (1982), includes isolation among its selection critera. Therefore, in comparison with the cores of rich clusters, Hickson's compact groups (HCGs) appear to be the densest isolated regions in the Universe (in galaxies per unit volume), and thus provide in principle a clean laboratory for studying the competition of very strong gravitational interactions. The $64,000 question here is then: Are compact groups really bound systems as dense as they appear? If dense groups indeed exist, then one expects that each of the dynamical processes leading to the interaction of their member galaxies should be greatly enhanced. This leads us to the questions: How stable are dense groups? How do they form? And the related question, fascinating to any theorist: What dynamical processes predominate in dense groups of galaxies? If HCGs are not bound dense systems, but instead 1D change alignments (Mamon 1986, 1987; Walke & Mamon 1989) or 3D transient cores (Rose 1979) within larger looser systems of galaxies, then the relevant question is: How frequent are chance configurations within loose groups? Here, the author answers these last four questions after comparing in some detail the methods used and the results obtained in the different studies of dense groups.

Develop a PWL System for Dense Graded Hot Mix Asphalt Construction, Including Pay Factors

DOT National Transportation Integrated Search

2015-01-01

This research project developed a PWL system that the Nevada DOT can effectively implement on the construction of dense graded HMA mixtures. The PWL system includes pay factors that are based on pavement performance indicators such as rutting and cra...

Scalable nuclear density functional theory with Sky3D

NASA Astrophysics Data System (ADS)

Afibuzzaman, Md; Schuetrumpf, Bastian; Aktulga, Hasan Metin

2018-02-01

In nuclear astrophysics, quantum simulations of large inhomogeneous dense systems as they appear in the crusts of neutron stars present big challenges. The number of particles in a simulation with periodic boundary conditions is strongly limited due to the immense computational cost of the quantum methods. In this paper, we describe techniques for an efficient and scalable parallel implementation of Sky3D, a nuclear density functional theory solver that operates on an equidistant grid. Presented techniques allow Sky3D to achieve good scaling and high performance on a large number of cores, as demonstrated through detailed performance analysis on a Cray XC40 supercomputer.

Low-voltage organic field effect transistors with a 2-tridecyl[1]benzothieno[3,2-b][1]benzothiophene semiconductor layer.

PubMed

Amin, Atefeh Y; Khassanov, Artoem; Reuter, Knud; Meyer-Friedrichsen, Timo; Halik, Marcus

2012-10-10

An asymmetric n-alkyl substitution pattern was realized in 2-tridecyl[1]benzothieno[3,2-b][1]benzothiophene (C(13)-BTBT) in order to improve the charge transport properties in organic thin-film transistors. We obtained large hole mobilities up to 17.2 cm(2)/(V·s) in low-voltage operating devices. The large mobility is related to densely packed layers of the BTBT π-systems at the channel interface dedicated to the substitution motif and confirmed by X-ray reflectivity measurements. The devices exhibit promising stability in continuous operation for several hours in ambient air.

Preliminary research on flow rate and free surface of the accelerator driven subcritical system gravity-driven dense granular-flow target

PubMed Central

Li, Xiaodong; Wan, Jiangfeng; Zhang, Sheng; Lin, Ping; Zhang, Yanshi; Yang, Guanghui; Wang, Mengke; Duan, Wenshan; Sun, Jian’an

2017-01-01

A spallation target is one of the three core parts of the accelerator driven subcritical system (ADS), which has already been investigated for decades. Recently, a gravity-driven Dense Granular-flow Target (DGT) is proposed, which consists of a cylindrical hopper and an internal coaxial cylindrical beam pipe. The research on the flow rate and free surface are important for the design of the target whether in Heavy Liquid Metal (HLM) targets or the DGT. In this paper, the relations of flow rate and the geometry of the DGT are investigated. Simulations based on the discrete element method (DEM) implementing on Graphics Processing Units (GPUs) and experiments are both performed. It is found that the existence of an internal pipe doesn’t influence the flow rate when the distance from the bottom of the pipe to orifice is large enough even in a larger system. Meanwhile, snapshots of the free surface formed just below the beam pipe are given. It is observed that the free surface is stable over time. The entire research is meaningful for the design of DGT. PMID:29095910

Preliminary research on flow rate and free surface of the accelerator driven subcritical system gravity-driven dense granular-flow target.

PubMed

Li, Xiaodong; Wan, Jiangfeng; Zhang, Sheng; Lin, Ping; Zhang, Yanshi; Yang, Guanghui; Wang, Mengke; Duan, Wenshan; Sun, Jian'an; Yang, Lei

2017-01-01

A spallation target is one of the three core parts of the accelerator driven subcritical system (ADS), which has already been investigated for decades. Recently, a gravity-driven Dense Granular-flow Target (DGT) is proposed, which consists of a cylindrical hopper and an internal coaxial cylindrical beam pipe. The research on the flow rate and free surface are important for the design of the target whether in Heavy Liquid Metal (HLM) targets or the DGT. In this paper, the relations of flow rate and the geometry of the DGT are investigated. Simulations based on the discrete element method (DEM) implementing on Graphics Processing Units (GPUs) and experiments are both performed. It is found that the existence of an internal pipe doesn't influence the flow rate when the distance from the bottom of the pipe to orifice is large enough even in a larger system. Meanwhile, snapshots of the free surface formed just below the beam pipe are given. It is observed that the free surface is stable over time. The entire research is meaningful for the design of DGT.

Effect of collisions on neutrino flavor inhomogeneity in a dense neutrino gas

DOE PAGES

Cirigliano, Vincenzo; Paris, Mark W.; Shalgar, Shashank

2017-09-25

We investigate the stability, with respect to spatial inhomogeneity, of a two-dimensional dense neutrino gas. The system exhibits growth of seed inhomogeneity due to nonlinear coherent neutrino self-interactions. In the absence of incoherent collisional effects, we also observe a dependence of this instability growth rate on the neutrino mass spectrum: the normal neutrino mass hierarchy exhibits spatial instability over a larger range of neutrino number density compared to that of the inverted case. Furthermore, we consider the effect of elastic incoherent collisions of the neutrinos with a static background of heavy, nucleon-like scatterers. At small scales, the growth of flavormore » instability can be suppressed by collisions. At large length scales we find, perhaps surprisingly, that for inverted neutrino mass hierarchy incoherent collisions fail to suppress flavor instabilities, independent of the coupling strength.« less

Recent Results on SNRs and PWNe from the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Hays, Elizabeth

2010-01-01

a) Symbiotic Binary System: White dwarf + red giant system. b) Nova: White dwarf builds up mass envelope to the point of thermonuclear fusion. c) Dramatic increase in visual magnitude. d) Recurrent Nova? e) Hints but no strong confirmation of previous nova f) Pre-nova activity: 1) White dwarf shows ongoing variability at level of several in magnitude. 2) V407 Cyg companion is a Mira star showing variability at level of several in magnitude. g) Origin of the gamma rays? 1) Strong shock propagating into dense medium around giant star land stellar wind. 2) Pion decay or electron processes?

The Continued Reduction in Dense Fog in the Southern California Region: Possible Causes

NASA Astrophysics Data System (ADS)

LaDochy, S.; Witiw, M.

2012-05-01

Dense fog appears to be decreasing in many parts of the world, especially in western cities. Dense fog (visibility <400 m) is disappearing in the urban southern California area also. There the decrease in dense fog events can be explained mainly by declining particulate levels, Pacific sea surface temperatures (SST), and increased urban warming. Using hourly data from 1948 to the present, we looked at the relationship between fog events in the region and contributing factors and trends over time. Initially a strong relationship was suggested between the occurrence of dense fog and the phases of an atmosphere-ocean cycle: the Pacific Decadal Oscillation (PDO). However, closer analysis revealed the importance to fog variability of an increasing urban heat island and the amount of atmospheric suspended particulate matter. Results show a substantial decrease in the occurrence of very low visibilities (<400 m) at the two airport stations in close proximity to the Pacific Ocean, LAX (Los Angeles International) and LGB (Long Beach International). A downward trend in particulate concentrations, coupled with an upward trend in urban temperatures were associated with the decrease in dense fog occurrence at both LAX and LGB. LAX dense fog that reached over 300 h in 1950 dropped steadily, with 0 h recorded in 1997. Since 1997, there has been a slight recovery with both 2008 and 2009 recording over 30 h of dense fog at both locations. In this study we examine whether the upturn is a temporary reversal of the trend. To remove the urban effect, we also included fog data from Vandenberg Air Force Base (VBG), located in a relatively sparsely populated area approximately 200 km to the north of metropolitan Los Angeles. Particulates, urban heat island, and Pacific SSTs all seem to be contributing factors to the decrease in fog in southern California, along with large-scale atmosphere-ocean interaction cycles. Case studies of local and regional dense fog in southern California point to the importance of strong, low inversions and to a lesser contributor, Santa Ana winds. Both are associated with large-scale atmospheric circulation patterns, which have changed markedly over the period of studied. These changes point to continued decreases in dense fog in the region.

Uniform, dense arrays of vertically aligned, large-diameter single-walled carbon nanotubes.

PubMed

Han, Zhao Jun; Ostrikov, Kostya

2012-04-04

Precisely controlled reactive chemical vapor synthesis of highly uniform, dense arrays of vertically aligned single-walled carbon nanotubes (SWCNTs) using tailored trilayered Fe/Al(2)O(3)/SiO(2) catalyst is demonstrated. More than 90% population of thick nanotubes (>3 nm in diameter) can be produced by tailoring the thickness and microstructure of the secondary catalyst supporting SiO(2) layer, which is commonly overlooked. The proposed model based on the atomic force microanalysis suggests that this tailoring leads to uniform and dense arrays of relatively large Fe catalyst nanoparticles on which the thick SWCNTs nucleate, while small nanotubes and amorphous carbon are effectively etched away. Our results resolve a persistent issue of selective (while avoiding multiwalled nanotubes and other carbon nanostructures) synthesis of thick vertically aligned SWCNTs whose easily switchable thickness-dependent electronic properties enable advanced applications in nanoelectronic, energy, drug delivery, and membrane technologies.

Photometric study of single-shot energy-dispersive x-ray diffraction at a laser plasma facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoidn, O. R.; Seidler, G. T., E-mail: seidler@uw.edu

The low repetition rates and possible shot-to-shot variations in laser-plasma studies place a high value on single-shot diagnostics. For example, white-beam scattering methods based on broadband backlighter x-ray sources are used to determine changes in the structure of laser-shocked crystalline materials by the evolution of coincidences of reciprocal lattice vectors and kinematically allowed momentum transfers. Here, we demonstrate that white-beam techniques can be extended to strongly disordered dense plasma and warm dense matter systems where reciprocal space is only weakly structured and spectroscopic detection is consequently needed to determine the static structure factor and thus, the ion-ion radial distribution function.more » Specifically, we report a photometric study of energy-dispersive x-ray diffraction (ED-XRD) for structural measurement of high energy density systems at large-scale laser facilities such as OMEGA and the National Ignition Facility. We find that structural information can be obtained in single-shot ED-XRD experiments using established backlighter and spectrometer technologies.« less

Satellite Relay Telemetry of Seismic Data in Earthquake Prediction and Control

NASA Technical Reports Server (NTRS)

Jackson, W. H.; Eaton, J. P.

1971-01-01

The Satellite Telemetry Earthquake Monitoring Program was started to evaluate the applicability of satellite relay telemetry in the collection of seismic data from a large number of dense seismograph clusters laid out along the major fault systems of western North America. Prototype clusters utilizing phone-line telemetry were then being installed by the National Center for Earthquake Research in 3 regions along the San Andreas fault in central California; and the experience of installing and operating the clusters and in reducing and analyzing the seismic data from them was to provide the raw materials for evaluation in the satellite relay telemetry project. The principal advantages of the satellite relay system over commercial telephone or microwave systems were: (1) it could be made less prone to massive failure during a major earthquake; (2) it could be extended readily into undeveloped regions; and (3) it could provide flexible, uniform communications over large sections of major global tectonic zones. Fundamental characteristics of a communications system to cope with the large volume of raw data collected by a short-period seismograph network are discussed.

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids.

PubMed

Dahlberg, Jerry; Tkacik, Peter T; Mullany, Brigid; Fleischhauer, Eric; Shahinian, Hossein; Azimi, Farzad; Navare, Jayesh; Owen, Spencer; Bisel, Tucker; Martin, Tony; Sholar, Jodie; Keanini, Russell G

2017-12-04

An analog, macroscopic method for studying molecular-scale hydrodynamic processes in dense gases and liquids is described. The technique applies a standard fluid dynamic diagnostic, particle image velocimetry (PIV), to measure: i) velocities of individual particles (grains), extant on short, grain-collision time-scales, ii) velocities of systems of particles, on both short collision-time- and long, continuum-flow-time-scales, iii) collective hydrodynamic modes known to exist in dense molecular fluids, and iv) short- and long-time-scale velocity autocorrelation functions, central to understanding particle-scale dynamics in strongly interacting, dense fluid systems. The basic system is composed of an imaging system, light source, vibrational sensors, vibrational system with a known media, and PIV and analysis software. Required experimental measurements and an outline of the theoretical tools needed when using the analog technique to study molecular-scale hydrodynamic processes are highlighted. The proposed technique provides a relatively straightforward alternative to photonic and neutron beam scattering methods traditionally used in molecular hydrodynamic studies.

Textural evolution of magma during the 9.4-ka trachytic explosive eruption at Kilian Volcano, Chaîne des Puys, France

NASA Astrophysics Data System (ADS)

Colombier, M.; Gurioli, L.; Druitt, T. H.; Shea, T.; Boivin, P.; Miallier, D.; Cluzel, N.

2017-02-01

Textural parameters such as density, porosity, pore connectivity, permeability, and vesicle size distributions of vesiculated and dense pyroclasts from the 9.4-ka eruption of Kilian Volcano, were quantified to constrain conduit and eruptive processes. The eruption generated a sequence of five vertical explosions of decreasing intensity, producing pyroclastic density currents and tephra fallout. The initial and final phases of the eruption correspond to the fragmentation of a degassed plug, as suggested by the increase of dense juvenile clasts (bimodal density distributions) as well as non-juvenile clasts, resulting from the reaming of a crater. In contrast, the intermediate eruptive phases were the results of more open-conduit conditions (unimodal density distributions, decreases in dense juvenile pyroclasts, and non-juvenile clasts). Vesicles within the pyroclasts are almost fully connected; however, there are a wide range of permeabilities, especially for the dense juvenile clasts. Textural analysis of the juvenile clasts reveals two vesiculation events: (1) an early nucleation event at low decompression rates during slow magma ascent producing a population of large bubbles (>1 mm) and (2) a syn-explosive nucleation event, followed by growth and coalescence of small bubbles controlled by high decompression rates immediately prior to or during explosive fragmentation. The similarities in pyroclast textures between the Kilian explosions and those at Soufrière Hills Volcano on Montserrat, in 1997, imply that eruptive processes in the two systems were rather similar and probably common to vulcanian eruptions in general.

Breast Density Legislation: Discussion of Patient Utilization and Subsequent Direct Financial Ramifications for Insurance Providers.

PubMed

Sobotka, John; Hinrichs, Clay

2015-10-01

Now that New Jersey has become the 14th state in the United States to enact legislation regarding dense breast screening, its patients are eligible to receive screening breast sonography coverage from their insurance carriers. This law is intended to improve breast cancer detection in patients with dense breasts and create awareness of unique issues that come with dense breast tissue, while reinforcing already present efforts to reduce the incidence of and morbidity related to the diagnosis of breast cancer. The aim of this study was to examine data from months preceding the effective date of this legislation in a community hospital setting and compare these data with data from months immediately after, and 6 months after, its enactment to present patient participation data and estimate the legislation's direct financial ramifications. Detractors of this type of legislation worry about overburdening the health care system with an influx of patients. Although there is a lack of present studies confirming this suspicion in other states with dense breast legislation, this study confirms a large increase in patient utilization after enactment, showing a minimum relative increase of 176.90% and a maximum relative increase of 335.56% in patient utilization of screening breast sonography. The investigators further include an estimation of an increased direct cost for insurers of $4,910,899.18 to $9,848,897.96 for a given month. Copyright © 2015 American College of Radiology. Published by Elsevier Inc. All rights reserved.

A Generic and Efficient E-field Parallel Imaging Correlator for Next-Generation Radio Telescopes

NASA Astrophysics Data System (ADS)

Thyagarajan, Nithyanandan; Beardsley, Adam P.; Bowman, Judd D.; Morales, Miguel F.

2017-05-01

Modern radio telescopes are favouring densely packed array layouts with large numbers of antennas (NA ≳ 1000). Since the complexity of traditional correlators scales as O(N_A^2), there will be a steep cost for realizing the full imaging potential of these powerful instruments. Through our generic and efficient E-field Parallel Imaging Correlator (epic), we present the first software demonstration of a generalized direct imaging algorithm, namely the Modular Optimal Frequency Fourier imager. Not only does it bring down the cost for dense layouts to O(N_A log _2N_A) but can also image from irregular layouts and heterogeneous arrays of antennas. epic is highly modular, parallelizable, implemented in object-oriented python, and publicly available. We have verified the images produced to be equivalent to those from traditional techniques to within a precision set by gridding coarseness. We have also validated our implementation on data observed with the Long Wavelength Array (LWA1). We provide a detailed framework for imaging with heterogeneous arrays and show that epic robustly estimates the input sky model for such arrays. Antenna layouts with dense filling factors consisting of a large number of antennas such as LWA, the Square Kilometre Array, Hydrogen Epoch of Reionization Array, and Canadian Hydrogen Intensity Mapping Experiment will gain significant computational advantage by deploying an optimized version of epic. The algorithm is a strong candidate for instruments targeting transient searches of fast radio bursts as well as planetary and exoplanetary phenomena due to the availability of high-speed calibrated time-domain images and low output bandwidth relative to visibility-based systems.

Modelling the light-scattering properties of a planetary-regolith analog sample

NASA Astrophysics Data System (ADS)

Vaisanen, T.; Markkanen, J.; Hadamcik, E.; Levasseur-Regourd, A. C.; Lasue, J.; Blum, J.; Penttila, A.; Muinonen, K.

2017-12-01

Solving the scattering properties of asteroid surfaces can be made cheaper, faster, and more accurate with reliable physics-based electromagnetic scattering programs for large and dense random media. Existing exact methods fail to produce solutions for such large systems and it is essential to develop approximate methods. Radiative transfer (RT) is an approximate method which works for sparse random media such as atmospheres fails when applied to dense media. In order to make the method applicable to dense media, we have developed a radiative-transfer coherent-backscattering method (RT-CB) with incoherent interactions. To show the current progress with the RT-CB, we have modeled a planetary-regolith analog sample. The analog sample is a low-density agglomerate produced by random ballistic deposition of almost equisized silicate spheres studied using the PROGRA2-surf experiment. The scattering properties were then computed with the RT-CB assuming that the silicate spheres were equisized and that there were a Gaussian particle size distribution. The results were then compared to the measured data and the intensity plot is shown below. The phase functions are normalized to unity at the 40-deg phase angle. The tentative intensity modeling shows good match with the measured data, whereas the polarization modeling shows discrepancies. In summary, the current RT-CB modeling is promising, but more work needs to be carried out, in particular, for modeling the polarization. Acknowledgments. Research supported by European Research Council with Advanced Grant No. 320773 SAEMPL, Scattering and Absorption of ElectroMagnetic waves in ParticuLate media. Computational resources provided by CSC - IT Centre for Science Ltd, Finland.

Probing properties of hot and dense QCD matter with heavy flavor in the PHENIX experiment at RHIC

DOE PAGES

Nouicer, Rachid

2015-05-29

Hadrons carrying heavy quarks, i.e. charm or bottom, are important probes of the hot and dense medium created in relativistic heavy ion collisions. Heavy quark-antiquark pairs are mainly produced in initial hard scattering processes of partons. While some of the produced pairs form bound quarkonia, the vast majority hadronize into particles carrying open heavy flavor. Heavy quark production has been studied by the PHENIX experiment at RHIC via measurements of single leptons from semi-leptonic decays in both the electron channel at mid-rapidity and in the muon channel at forward rapidity. A large suppression and azimuthal anisotropy of single electrons havemore » been observed in Au + Au collisions at 200 GeV. These results suggest a large energy loss and flow of heavy quarks in the hot, dense matter. The PHENIX experiment has also measured J/ψ production at 200 GeV in p + p, d + Au, Cu + Cu and Au + Au collisions, both at mid- and forward-rapidities, and additionally Cu + Au and U + U at forward-rapidities. In the most energetic collisions, more suppression is observed at forward rapidity than at central rapidity. This can be interpreted either as a sign of quark recombination, or as a hint of additional cold nuclear matter effects. The centrality dependence of nuclear modification factor, R AA(p T), for J/ψ in U + U collisions at √ sNN = 193 GeV shows a similar trend to the lighter systems, Au + Au and Cu + Cu, at similar energy 200 GeV.« less

Fast and Robust Registration of Multimodal Remote Sensing Images via Dense Orientated Gradient Feature

NASA Astrophysics Data System (ADS)

Ye, Y.

2017-09-01

This paper presents a fast and robust method for the registration of multimodal remote sensing data (e.g., optical, LiDAR, SAR and map). The proposed method is based on the hypothesis that structural similarity between images is preserved across different modalities. In the definition of the proposed method, we first develop a pixel-wise feature descriptor named Dense Orientated Gradient Histogram (DOGH), which can be computed effectively at every pixel and is robust to non-linear intensity differences between images. Then a fast similarity metric based on DOGH is built in frequency domain using the Fast Fourier Transform (FFT) technique. Finally, a template matching scheme is applied to detect tie points between images. Experimental results on different types of multimodal remote sensing images show that the proposed similarity metric has the superior matching performance and computational efficiency than the state-of-the-art methods. Moreover, based on the proposed similarity metric, we also design a fast and robust automatic registration system for multimodal images. This system has been evaluated using a pair of very large SAR and optical images (more than 20000 × 20000 pixels). Experimental results show that our system outperforms the two popular commercial software systems (i.e. ENVI and ERDAS) in both registration accuracy and computational efficiency.

On the Viability of Using Autonomous Three-Component Nodal Geophones to Calculate Teleseismic Ps Receiver Functions with an Application to the Old Faithful Hydrothermal System and the Cascadia Subduction Zone

NASA Astrophysics Data System (ADS)

Ward, K. M.; Lin, F. C.

2017-12-01

Recent advances in seismic data-acquisition technology paired with an increasing interest from the academic passive source seismological community have opened up new scientific targets and imaging possibilities, often referred to as Large-N experiments (large number of instruments). The success of these and other deployments has motivated individual researchers, as well as the larger seismological community, to invest in the next generation of nodal geophones. Although the new instruments have battery life and bandwidth limitations compared to broadband instruments, the relatively low deployment and procurement cost of these new nodal geophones provides an additional novel tool for researchers. Here, we explore the viability of using autonomous three-component nodal geophones to calculate teleseismic Ps receiver functions by comparison of co-located broadband stations and highlight some potential advantages with a dense nodal array deployed around the Upper Geyser basin in Yellowstone National Park. Two key findings from this example include (1) very dense nodal arrays can be used to image small-scale features in the shallow crust that typical broadband station spacing would alias, and (2) nodal arrays with a larger footprint could be used to image deeper features with greater or equal detail as typical broadband deployments but at a reduced deployment cost. The success of the previous example has motivated a larger 2-D line across the Cascadia subduction zone. In the summer of 2017, we deployed 174 nodal geophones with an average site spacing of 750 m. Synthetic tests with dense station spacing ( 1 km) reveal subtler features of the system that is consistent with our preliminary receiver function results from our Cascadia deployment. With the increasing availability of nodal geophones to individual researchers and the successful demonstration that nodal geophones are a viable instrument for receiver function studies, numerous scientific targets can be investigated at reduced costs or in expanded detail.

Use of herbicides on forest lands in southwestern Oregon.

Treesearch

H.J. Gratkowski

1961-01-01

A substantial portion of the commercial forest land in southwestern Oregon is occupied by dense stands of brush species or by understocked stands of conifers with a dense understory of brush. Individual brushfields range in size from small patches a few acres in extent to large, continuous areas covering more than 10,000 acres. Climatically, the area is warmer and...

A nutrient-dense, high fiber, fruit-based supplement bar increases HDL, particularly large HDL, lowers homocysteine, and raises glutathione in a 2-week trial

USDA-ARS?s Scientific Manuscript database

Dietary intake modulates disease risk, but little is known as to how components within food mixtures affect pathophysiology. Here, a low-calorie, high-fiber, fruit-based nutrient-dense bar of defined composition (e.g., vitamins/minerals, fruit polyphenolics, B-glucan, docosahexaenoic acid (DHA)) app...

Extracting Communities from Complex Networks by the k-Dense Method

NASA Astrophysics Data System (ADS)

Saito, Kazumi; Yamada, Takeshi; Kazama, Kazuhiro

To understand the structural and functional properties of large-scale complex networks, it is crucial to efficiently extract a set of cohesive subnetworks as communities. There have been proposed several such community extraction methods in the literature, including the classical k-core decomposition method and, more recently, the k-clique based community extraction method. The k-core method, although computationally efficient, is often not powerful enough for uncovering a detailed community structure and it produces only coarse-grained and loosely connected communities. The k-clique method, on the other hand, can extract fine-grained and tightly connected communities but requires a substantial amount of computational load for large-scale complex networks. In this paper, we present a new notion of a subnetwork called k-dense, and propose an efficient algorithm for extracting k-dense communities. We applied our method to the three different types of networks assembled from real data, namely, from blog trackbacks, word associations and Wikipedia references, and demonstrated that the k-dense method could extract communities almost as efficiently as the k-core method, while the qualities of the extracted communities are comparable to those obtained by the k-clique method.

Influence of galactic arm scale dynamics on the molecular composition of the cold and dense ISM. I. Observed abundance gradients in dense clouds

NASA Astrophysics Data System (ADS)

Ruaud, M.; Wakelam, V.; Gratier, P.; Bonnell, I. A.

2018-04-01

Aim. We study the effect of large scale dynamics on the molecular composition of the dense interstellar medium during the transition between diffuse to dense clouds. Methods: We followed the formation of dense clouds (on sub-parsec scales) through the dynamics of the interstellar medium at galactic scales. We used results from smoothed particle hydrodynamics (SPH) simulations from which we extracted physical parameters that are used as inputs for our full gas-grain chemical model. In these simulations, the evolution of the interstellar matter is followed for 50 Myr. The warm low-density interstellar medium gas flows into spiral arms where orbit crowding produces the shock formation of dense clouds, which are held together temporarily by the external pressure. Results: We show that depending on the physical history of each SPH particle, the molecular composition of the modeled dense clouds presents a high dispersion in the computed abundances even if the local physical properties are similar. We find that carbon chains are the most affected species and show that these differences are directly connected to differences in (1) the electronic fraction, (2) the C/O ratio, and (3) the local physical conditions. We argue that differences in the dynamical evolution of the gas that formed dense clouds could account for the molecular diversity observed between and within these clouds. Conclusions: This study shows the importance of past physical conditions in establishing the chemical composition of the dense medium.

Novel method for measuring a dense 3D strain map of robotic flapping wings

NASA Astrophysics Data System (ADS)

Li, Beiwen; Zhang, Song

2018-04-01

Measuring dense 3D strain maps of the inextensible membranous flapping wings of robots is of vital importance to the field of bio-inspired engineering. Conventional high-speed 3D videography methods typically reconstruct the wing geometries through measuring sparse points with fiducial markers, and thus cannot obtain the full-field mechanics of the wings in detail. In this research, we propose a novel system to measure a dense strain map of inextensible membranous flapping wings by developing a superfast 3D imaging system and a computational framework for strain analysis. Specifically, first we developed a 5000 Hz 3D imaging system based on the digital fringe projection technique using the defocused binary patterns to precisely measure the dynamic 3D geometries of rapidly flapping wings. Then, we developed a geometry-based algorithm to perform point tracking on the precisely measured 3D surface data. Finally, we developed a dense strain computational method using the Kirchhoff-Love shell theory. Experiments demonstrate that our method can effectively perform point tracking and measure a highly dense strain map of the wings without many fiducial markers.

Whale sharks target dense prey patches of sergestid shrimp off Tanzania

PubMed Central

Rohner, Christoph A.; Armstrong, Amelia J.; Pierce, Simon J.; Prebble, Clare E. M.; Cagua, E. Fernando; Cochran, Jesse E. M.; Berumen, Michael L.; Richardson, Anthony J.

2015-01-01

Large planktivores require high-density prey patches to make feeding energetically viable. This is a major challenge for species living in tropical and subtropical seas, such as whale sharks Rhincodon typus. Here, we characterize zooplankton biomass, size structure and taxonomic composition from whale shark feeding events and background samples at Mafia Island, Tanzania. The majority of whale sharks were feeding (73%, 380 of 524 observations), with the most common behaviour being active surface feeding (87%). We used 20 samples collected from immediately adjacent to feeding sharks and an additional 202 background samples for comparison to show that plankton biomass was ∼10 times higher in patches where whale sharks were feeding (25 vs. 2.6 mg m−3). Taxonomic analyses of samples showed that the large sergestid Lucifer hanseni (∼10 mm) dominated while sharks were feeding, accounting for ∼50% of identified items, while copepods (<2 mm) dominated background samples. The size structure was skewed towards larger animals representative of L.hanseni in feeding samples. Thus, whale sharks at Mafia Island target patches of dense, large, zooplankton dominated by sergestids. Large planktivores, such as whale sharks, which generally inhabit warm oligotrophic waters, aggregate in areas where they can feed on dense prey to obtain sufficient energy. PMID:25814777

C3 glomerulonephritis and dense deposit disease share a similar disease course in a large United States cohort of patients with C3 glomerulopathy.

PubMed

Bomback, Andrew S; Santoriello, Dominick; Avasare, Rupali S; Regunathan-Shenk, Renu; Canetta, Pietro A; Ahn, Wooin; Radhakrishnan, Jai; Marasa, Maddalena; Rosenstiel, Paul E; Herlitz, Leal C; Markowitz, Glen S; D'Agati, Vivette D; Appel, Gerald B

2018-04-01

C3 glomerulonephritis (C3GN) and dense deposit disease comprise the two classes of C3 glomerulopathy. Studies from Europe and Asia have aided our understanding of this recently defined disorder, but whether these data apply to a diverse United States patient population remains unclear. We, therefore, reviewed clinical and histopathological data, including generation of a C3 Glomerulopathy Histologic Index to score biopsy activity and chronicity, to determine predictors of progression to end-stage renal disease (ESRD) and advanced chronic kidney disease (CKD) in 111 patients (approximately 35% non-white) with C3 glomerulopathy: 87 with C3GN and 24 with dense deposit disease. Complement-associated gene variants and autoantibodies were detected in 24% and 35% of screened patients, respectively. Our C3 Glomerulopathy Histologic Index denoted higher activity in patients with C3GN and higher chronicity in patients with dense deposit disease. Over an average of 72 months of follow-up, remission occurred in 38% of patients with C3GN and 25% of patients with dense deposit disease. Progression to late-stage CKD and ESRD was common, with no differences between C3GN (39%) and dense deposit disease (42%). In multivariable models, the strongest predictors for progression were estimated glomerular filtration rate at diagnosis (clinical variables model) and tubular atrophy/interstitial fibrosis (histopathology variables model). Using our C3 Glomerulopathy Histologic Index, both total activity and total chronicity scores emerged as the strongest predictors of progression. Thus, in a large, diverse American cohort of patients with C3 glomerulopathy, there is a high rate of progression to CKD and ESRD with no differences between C3GN and dense deposit disease. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Propulsion and Power Generation Capabilities of a Dense Plasma Focus (DPF) Fusion System for Future Military Aerospace Vehicles (POSTPRINT)

DTIC Science & Technology

2005-10-06

The objective of this study was to perform a parametric evaluation of the performance and interface characteristics of a dense plasma focus (DPF...dense plasma focus (DPF) fusion power and propulsion technology, with advanced waverider-like airframe configurations utilizing air-breathing MHD

On the unreasonable effectiveness of the post-Newtonian approximation in gravitational physics

PubMed Central

Will, Clifford M.

2011-01-01

The post-Newtonian approximation is a method for solving Einstein’s field equations for physical systems in which motions are slow compared to the speed of light and where gravitational fields are weak. Yet it has proven to be remarkably effective in describing certain strong-field, fast-motion systems, including binary pulsars containing dense neutron stars and binary black hole systems inspiraling toward a final merger. The reasons for this effectiveness are largely unknown. When carried to high orders in the post-Newtonian sequence, predictions for the gravitational-wave signal from inspiraling compact binaries will play a key role in gravitational-wave detection by laser-interferometric observatories. PMID:21447714

Real-time detection of moving objects from moving vehicles using dense stereo and optical flow

NASA Technical Reports Server (NTRS)

Talukder, Ashit; Matthies, Larry

2004-01-01

Dynamic scene perception is very important for autonomous vehicles operating around other moving vehicles and humans. Most work on real-time object tracking from moving platforms has used sparse features or assumed flat scene structures. We have recently extended a real-time, dense stereo system to include realtime, dense optical flow, enabling more comprehensive dynamic scene analysis. We describe algorithms to robustly estimate 6-DOF robot egomotion in the presence of moving objects using dense flow and dense stereo. We then use dense stereo and egomotion estimates to identify & other moving objects while the robot itself is moving. We present results showing accurate egomotion estimation and detection of moving people and vehicles under general 6-DOF motion of the robot and independently moving objects. The system runs at 18.3 Hz on a 1.4 GHz Pentium M laptop, computing 160x120 disparity maps and optical flow fields, egomotion, and moving object segmentation. We believe this is a significant step toward general unconstrained dynamic scene analysis for mobile robots, as well as for improved position estimation where GPS is unavailable.

Real-time detection of moving objects from moving vehicles using dense stereo and optical flow

NASA Technical Reports Server (NTRS)

Talukder, Ashit; Matthies, Larry

2004-01-01

Dynamic scene perception is very important for autonomous vehicles operating around other moving vehicles and humans. Most work on real-time object tracking from moving platforms has used sparse features or assumed flat scene structures. We have recently extended a real-time, dense stereo system to include real-time, dense optical flow, enabling more comprehensive dynamic scene analysis. We describe algorithms to robustly estimate 6-DOF robot egomotion in the presence of moving objects using dense flow and dense stereo. We then use dense stereo and egomotion estimates to identity other moving objects while the robot itself is moving. We present results showing accurate egomotion estimation and detection of moving people and vehicles under general 6-DOF motion of the robot and independently moving objects. The system runs at 18.3 Hz on a 1.4 GHz Pentium M laptop, computing 160x120 disparity maps and optical flow fields, egomotion, and moving object segmentation. We believe this is a significant step toward general unconstrained dynamic scene analysis for mobile robots, as well as for improved position estimation where GPS is unavailable.

Real-time Detection of Moving Objects from Moving Vehicles Using Dense Stereo and Optical Flow

NASA Technical Reports Server (NTRS)

Talukder, Ashit; Matthies, Larry

2004-01-01

Dynamic scene perception is very important for autonomous vehicles operating around other moving vehicles and humans. Most work on real-time object tracking from moving platforms has used sparse features or assumed flat scene structures. We have recently extended a real-time. dense stereo system to include realtime. dense optical flow, enabling more comprehensive dynamic scene analysis. We describe algorithms to robustly estimate 6-DOF robot egomotion in the presence of moving objects using dense flow and dense stereo. We then use dense stereo and egomotion estimates to identify other moving objects while the robot itself is moving. We present results showing accurate egomotion estimation and detection of moving people and vehicles under general 6DOF motion of the robot and independently moving objects. The system runs at 18.3 Hz on a 1.4 GHz Pentium M laptop. computing 160x120 disparity maps and optical flow fields, egomotion, and moving object segmentation. We believe this is a significant step toward general unconstrained dynamic scene analysis for mobile robots, as well as for improved position estimation where GPS is unavailable.

The Relationship between the Dense Neutral and Diffuse Ionized Gas in the Thick Disks of Two Edge-on Spiral Galaxies

NASA Astrophysics Data System (ADS)

Rueff, Katherine M.; Howk, J. Christopher; Pitterle, Marissa; Hirschauer, Alec S.; Fox, Andrew J.; Savage, Blair D.

2013-03-01

We present high-resolution, optical images (BVI + Hα) of the multiphase interstellar medium (ISM) in the thick disks of the edge-on spiral galaxies NGC 4013 and NGC 4302. Our images from the Hubble Space Telescope (HST), Large Binocular Telescope, and WIYN 3.5 m telescope reveal an extensive population of filamentary dust absorption seen to z ~2-2.5 kpc. Many of these dusty thick disk structures have characteristics reminiscent of molecular clouds found in the Milky Way disk. Our Hα images show that the extraplanar diffuse ionized gas (DIG) in these galaxies is dominated by a smooth, diffuse component. The strongly filamentary morphologies of the dust absorption have no counterpart in the smoothly distributed Hα emission. We argue that the thick disk DIG and dust-bearing filaments trace physically distinct phases of the thick disk ISM, the latter tracing a dense, warm or cold neutral medium. The dense, dusty matter in the thick disks of spiral galaxies is largely tracing matter ejected from the thin disk via energetic feedback from massive stars. The high densities of the gas may be a result of converging gas flows. This dense material fuels some thick disk star formation, as evidenced by the presence of thick disk H II regions. Based on observations obtained with the NASA/ESA Hubble Space Telescope operated at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Also, based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the US, Italy, and Germany. LBT Corporation partners are the University of Arizona, on behalf of the Arizona University System; Instituto Nazionale do Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute of Potsdam, and Heidelberg University; Ohio State University, and the Research Corporation, on behalf of the University of Notre Dame, the University of Minnesota, and the University of Virginia. Also, based on observations obtained by the WIYN Observatory which is a joint facility of the University of Wisconsin-Madison, Yale University, Indiana University, and the National Optical Astronomy Observatories.

Self-diffusion in dense granular shear flows.

PubMed

Utter, Brian; Behringer, R P

2004-03-01

Diffusivity is a key quantity in describing velocity fluctuations in granular materials. These fluctuations are the basis of many thermodynamic and hydrodynamic models which aim to provide a statistical description of granular systems. We present experimental results on diffusivity in dense, granular shear flows in a two-dimensional Couette geometry. We find that self-diffusivities D are proportional to the local shear rate gamma; with diffusivities along the direction of the mean flow approximately twice as large as those in the perpendicular direction. The magnitude of the diffusivity is D approximately gamma;a(2), where a is the particle radius. However, the gradient in shear rate, coupling to the mean flow, and strong drag at the moving boundary lead to particle displacements that can appear subdiffusive or superdiffusive. In particular, diffusion appears to be superdiffusive along the mean flow direction due to Taylor dispersion effects and subdiffusive along the perpendicular direction due to the gradient in shear rate. The anisotropic force network leads to an additional anisotropy in the diffusivity that is a property of dense systems and has no obvious analog in rapid flows. Specifically, the diffusivity is suppressed along the direction of the strong force network. A simple random walk simulation reproduces the key features of the data, such as the apparent superdiffusive and subdiffusive behavior arising from the mean velocity field, confirming the underlying diffusive motion. The additional anisotropy is not observed in the simulation since the strong force network is not included. Examples of correlated motion, such as transient vortices, and Lévy flights are also observed. Although correlated motion creates velocity fields which are qualitatively different from collisional Brownian motion and can introduce nondiffusive effects, on average the system appears simply diffusive.

Right Ventricular Strain, Torsion, and Dyssynchrony in Healthy Subjects using 3D Spiral Cine DENSE Magnetic Resonance Imaging

PubMed Central

Suever, Jonathan D; Wehner, Gregory J; Jing, Linyuan; Powell, David K; Hamlet, Sean M; Grabau, Jonathan D; Mojsejenko, Dimitri; Andres, Kristin N; Haggerty, Christopher M; Fornwalt, Brandon K

2017-01-01

Mechanics of the left ventricle (LV) are important indicators of cardiac function. The role of right ventricular (RV) mechanics is largely unknown due to the technical limitations of imaging its thin wall and complex geometry and motion. By combining 3D Displacement Encoding with Stimulated Echoes (DENSE) with a post-processing pipeline that includes a local coordinate system, it is possible to quantify RV strain, torsion, and synchrony. In this study, we sought to characterize RV mechanics in 50 healthy individuals and compare these values to their LV counterparts. For each cardiac frame, 3D displacements were fit to continuous and differentiable radial basis functions, allowing for the computation of the 3D Cartesian Lagrangian strain tensor at any myocardial point. The geometry of the RV was extracted via a surface fit to manually delineated endocardial contours. Throughout the RV, a local coordinate system was used to transform from a Cartesian strain tensor to a polar strain tensor. It was then possible to compute peak RV torsion as well as peak longitudinal and circumferential strain. A comparable analysis was performed for the LV. Dyssynchrony was computed from the standard deviation of regional activation times. Global circumferential strain was comparable between the RV and LV (−18.0% for both) while longitudinal strain was greater in the RV (−18.1% vs. −15.7%). RV torsion was comparable to LV torsion (6.2 vs. 7.1 degrees, respectively). Regional activation times indicated that the RV contracted later but more synchronously than the LV. 3D spiral cine DENSE combined with a post–processing pipeline that includes a local coordinate system can resolve both the complex geometry and 3D motion of the RV. PMID:28055859

Commercial associative memory performance for applications in track-based triggers at the Large Hadron Collider

NASA Astrophysics Data System (ADS)

Webster, Jordan

2017-01-01

Dense track environments in pp collisions at the Large Hadron Collider (LHC) motivate the use of triggers with dedicated hardware for fast track reconstruction. The ATLAS Collaboration is in the process of implementing a Fast Tracker (FTK) trigger upgrade, in which Content Addressable Memories (CAMs) will be used to rapidly match hit patterns with large banks of simulated tracks. The FTK CAMs are produced primarily at the University of Pisa. However, commercial CAM technology is rapidly developing due to applications in computer networking devices. This poster presents new studies comparing FTK CAMs to cutting-edge ternary CAMs developed by Cavium. The comparison is intended to guide the design of future track-based trigger systems for the next Phase at the LHC.

New way to produce dense double-antikaonic dibaryon system, 𝐾̄𝐾̄NN, through Λ(1405)-doorway sticking in p + p collisions

PubMed Central

YAMAZAKI, Toshimitsu; AKAISHI, Yoshinori; HASSANVAND, Maryam

2011-01-01

A recent successful observation of a dense and deeply bound 𝐾̄ nuclear system, K−pp, in the p + p → K+ + K−pp reaction in a DISTO experiment indicates that the double-𝐾̄ dibaryon, K−K−pp, which was predicted to be a dense nuclear system, can also be formed in p + p collisions. We find theoretically that the K−-K− repulsion plays no significant role in reducing the density and binding energy of K−K−pp and that, when two Λ(1405) resonances are produced simultaneously in a short-range p + p collision, they act as doorways to copious formation of K−K−pp, if and only if K−K−pp is a dense object, as predicted. PMID:21670568

Optics and Nonlinear Buckling Mechanics in Large-Area, Highly Stretchable Arrays of Plasmonic Nanostructures.

PubMed

Gao, Li; Zhang, Yihui; Zhang, Hui; Doshay, Sage; Xie, Xu; Luo, Hongying; Shah, Deesha; Shi, Yan; Xu, Siyi; Fang, Hui; Fan, Jonathan A; Nordlander, Peter; Huang, Yonggang; Rogers, John A

2015-06-23

Large-scale, dense arrays of plasmonic nanodisks on low-modulus, high-elongation elastomeric substrates represent a class of tunable optical systems, with reversible ability to shift key optical resonances over a range of nearly 600 nm at near-infrared wavelengths. At the most extreme levels of mechanical deformation (strains >100%), nonlinear buckling processes transform initially planar arrays into three-dimensional configurations, in which the nanodisks rotate out of the plane to form linear arrays with "wavy" geometries. Analytical, finite-element, and finite-difference time-domain models capture not only the physics of these buckling processes, including all of the observed modes, but also the quantitative effects of these deformations on the plasmonic responses. The results have relevance to mechanically tunable optical systems, particularly to soft optical sensors that integrate on or in the human body.

Interpretation Time Using a Concurrent-Read Computer-Aided Detection System for Automated Breast Ultrasound in Breast Cancer Screening of Women With Dense Breast Tissue.

PubMed

Jiang, Yulei; Inciardi, Marc F; Edwards, Alexandra V; Papaioannou, John

2018-05-24

The purpose of this study was to compare diagnostic accuracy and interpretation time of screening automated breast ultrasound (ABUS) for women with dense breast tissue without and with use of a recently U.S. Food and Drug Administration-approved computer-aided detection (CAD) system for concurrent read. In a retrospective observer performance study, 18 radiologists interpreted a cancer-enriched set (i.e., cancer prevalence higher than in the original screening cohort) of 185 screening ABUS studies (52 with and 133 without breast cancer). These studies were from a large cohort of ABUS screened patients interpreted as BI-RADS density C or D. Each reader interpreted each case twice in a counterbalanced study, once without the CAD system and once with it, separated by 4 weeks. For each case, each reader identified abnormal findings and reported BI-RADS assessment category and level of suspicion for breast cancer. Interpretation time was recorded. Level of suspicion data were compared to evaluate diagnostic accuracy by means of the Dorfman-Berbaum-Metz method of jackknife with ANOVA ROC analysis. Interpretation times were compared by ANOVA. The ROC AUC was 0.848 with the CAD system, compared with 0.828 without it, for a difference of 0.020 (95% CI, -0.011 to 0.051) and was statistically noninferior to the AUC without the CAD system with respect to a margin of -0.05 (p = 0.000086). The mean interpretation time was 3 minutes 33 seconds per case without the CAD system and 2 minutes 24 seconds with it, for a difference of 1 minute 9 seconds saved (95% CI, 44-93 seconds; p = 0.000014), or a reduction in interpretation time to 67% of the time without the CAD system. Use of the concurrent-read CAD system for interpretation of screening ABUS studies of women with dense breast tissue who do not have symptoms is expected to make interpretation significantly faster and produce noninferior diagnostic accuracy compared with interpretation without the CAD system.

Progress on Ultra-Dense Quantum Communication Using Integrated Photonic Architecture

DTIC Science & Technology

2012-05-09

REPORT Progress on Ultra-Dense Quantum Communication Using Integrated Photonic Architecture 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: The goal of...including the development of a large-alphabet quantum key distribution protocol that uses measurements in mutually unbiased bases. 1. REPORT DATE (DD-MM... quantum information, integrated optics, photonic integrated chip Dirk Englund, Karl Berggren, Jeffrey Shapiro, Chee Wei Wong, Franco Wong, and Gregory

Five anthropogenic factors that will radically alter forest conditions and management needs in the Northern United States

Treesearch

Stephen R. Shifley; W. Keith Moser; David J. Nowak; Patrick D. Miles; Brett J. Butler; Francisco X. Aguilar; Ryan D. DeSantis; Eric J. Greenfield

2014-01-01

The Northern United States includes the 20 states bounded by Maine, Maryland, Missouri, and Minnesota. With 70 million ha of forestland and 124 million people, it is the most densely forested (42% of land area) and most densely populated (74 people/km2) quadrant of the United States. Three recent, large-scale, multiresource assessments of forest...

Chandra Observations of MS0440.5+0204 & MS0839.9+2938: Cooling Flow Clusters in Formation?

NASA Astrophysics Data System (ADS)

McNamara, Brian

2000-09-01

We propose to observe two redshift z~0.2 clusters, MS0839.9+2938 and MS0440+0204, discovered as bright X-ray sources in the Einstein Medium Sensitivity Survey. The cluster cores are structured in the X-ray and optical bands, and they harbor large cooling flows. Their central cluster galaxies contain luminous nebular emission systems, active star formation, and strong radio sources. Using the Chandra data, we will determine whether the large discrepancies between the X-ray cooling rates and optical star formation rates can be reconciled, and we will test the hypothesis that cooling flows form as cool, dense groups accrete into massive clusters.

Twin-mediated epitaxial growth of highly lattice-mismatched Cu/Ag core-shell nanowires.

PubMed

Weng, Wei-Lun; Hsu, Chin-Yu; Lee, Jheng-Syun; Fan, Hsin-Hsin; Liao, Chien-Neng

2018-05-31

Lattice-mismatch is an important factor for the heteroepitaxial growth of core-shell nanostructures. A large lattice-mismatch usually leads to a non-coherent interface or a polycrystalline shell layer. In this study, a conformal Ag layer is coated on Cu nanowires with dense nanoscale twin boundaries through a galvanic replacement reaction. Despite a large lattice mismatch between Ag and Cu (∼12.6%), the Ag shell replicates the twinning structure in Cu nanowires and grows epitaxially on the nanotwinned Cu nanowire. A twin-mediated growth mechanism is proposed to explain the epitaxy of high lattice-mismatch bimetallic systems in which the misfit dislocations are accommodated by coherent twin boundaries.

Explosive propulsion applications. [to future unmanned missions

NASA Technical Reports Server (NTRS)

Nakamura, Y.; Varsi, G.; Back, L. H.

1974-01-01

The feasibility and application of an explosive propulsion concept capable of supporting future unmanned missions in the post-1980 era were examined and recommendations made for advanced technology development tasks. The Venus large lander mission was selected as the first in which the explosive propulsion concept can find application. A conceptual design was generated and its performance, weight, costs, and interaction effects determined. Comparisons were made with conventional propulsion alternatives. The feasibility of the explosive propulsion system was verified for planetology experiments within the dense atmosphere of Venus as well as the outer planets. Additionally, it was determined that the Venus large lander mission could be augmented ballistically with a significant delivery margin.

An extended GS method for dense linear systems

NASA Astrophysics Data System (ADS)

Niki, Hiroshi; Kohno, Toshiyuki; Abe, Kuniyoshi

2009-09-01

Davey and Rosindale [K. Davey, I. Rosindale, An iterative solution scheme for systems of boundary element equations, Internat. J. Numer. Methods Engrg. 37 (1994) 1399-1411] derived the GSOR method, which uses an upper triangular matrix [Omega] in order to solve dense linear systems. By applying functional analysis, the authors presented an expression for the optimum [Omega]. Moreover, Davey and Bounds [K. Davey, S. Bounds, A generalized SOR method for dense linear systems of boundary element equations, SIAM J. Comput. 19 (1998) 953-967] also introduced further interesting results. In this note, we employ a matrix analysis approach to investigate these schemes, and derive theorems that compare these schemes with existing preconditioners for dense linear systems. We show that the convergence rate of the Gauss-Seidel method with preconditioner PG is superior to that of the GSOR method. Moreover, we define some splittings associated with the iterative schemes. Some numerical examples are reported to confirm the theoretical analysis. We show that the EGS method with preconditioner produces an extremely small spectral radius in comparison with the other schemes considered.

Soliton Turbulence in Shallow Water Ocean Surface Waves

NASA Astrophysics Data System (ADS)

Costa, Andrea; Osborne, Alfred R.; Resio, Donald T.; Alessio, Silvia; Chrivı, Elisabetta; Saggese, Enrica; Bellomo, Katinka; Long, Chuck E.

2014-09-01

We analyze shallow water wind waves in Currituck Sound, North Carolina and experimentally confirm, for the first time, the presence of soliton turbulence in ocean waves. Soliton turbulence is an exotic form of nonlinear wave motion where low frequency energy may also be viewed as a dense soliton gas, described theoretically by the soliton limit of the Korteweg-deVries equation, a completely integrable soliton system: Hence the phrase "soliton turbulence" is synonymous with "integrable soliton turbulence." For periodic-quasiperiodic boundary conditions the ergodic solutions of Korteweg-deVries are exactly solvable by finite gap theory (FGT), the basis of our data analysis. We find that large amplitude measured wave trains near the energetic peak of a storm have low frequency power spectra that behave as ˜ω-1. We use the linear Fourier transform to estimate this power law from the power spectrum and to filter densely packed soliton wave trains from the data. We apply FGT to determine the soliton spectrum and find that the low frequency ˜ω-1 region is soliton dominated. The solitons have random FGT phases, a soliton random phase approximation, which supports our interpretation of the data as soliton turbulence. From the probability density of the solitons we are able to demonstrate that the solitons are dense in time and highly non-Gaussian.

Dense image registration through MRFs and efficient linear programming.

PubMed

Glocker, Ben; Komodakis, Nikos; Tziritas, Georgios; Navab, Nassir; Paragios, Nikos

2008-12-01

In this paper, we introduce a novel and efficient approach to dense image registration, which does not require a derivative of the employed cost function. In such a context, the registration problem is formulated using a discrete Markov random field objective function. First, towards dimensionality reduction on the variables we assume that the dense deformation field can be expressed using a small number of control points (registration grid) and an interpolation strategy. Then, the registration cost is expressed using a discrete sum over image costs (using an arbitrary similarity measure) projected on the control points, and a smoothness term that penalizes local deviations on the deformation field according to a neighborhood system on the grid. Towards a discrete approach, the search space is quantized resulting in a fully discrete model. In order to account for large deformations and produce results on a high resolution level, a multi-scale incremental approach is considered where the optimal solution is iteratively updated. This is done through successive morphings of the source towards the target image. Efficient linear programming using the primal dual principles is considered to recover the lowest potential of the cost function. Very promising results using synthetic data with known deformations and real data demonstrate the potentials of our approach.

‘Teeth in the brain’ – a case of giant intracranial mature cystic teratoma

PubMed Central

O’Grady, John; Kobayter, Lina; Kaliaperumal, Chandrasekaran; O’Sullivan, Michael

2012-01-01

The authors describe a case of a giant intracranial mature cystic teratoma in a 16-year-old girl presenting acutely with a severe headache, vomiting and a complex generalised seizure with a background history of intermittent headaches for 3 years. CT and MRI brain demonstrated a ruptured large cystic teratoma encapsulating two large teeth within the diffusely dense fatty heterogeneous lesion. Surgical debulking of the cyst was performed and the calcific remnants were left behind owing to dense adhesion to the brain. The procedure was complicated by postoperative hydrocephalus and needed a ventricloperitoneal shunt. She is currently asymptomatic and undergoing rehabilitation. PMID:22707688

Observation of the ballooning mode that limits the operation space of the high-density super-dense-core plasma in the LHD

NASA Astrophysics Data System (ADS)

Ohdachi, S.; Watanabe, K. Y.; Tanaka, K.; Suzuki, Y.; Takemura, Y.; Sakakibara, S.; Du, X. D.; Bando, T.; Narushima, Y.; Sakamoto, R.; Miyazawa, J.; Motojima, G.; Morisaki, T.; LHD Experiment Group

2017-06-01

The central beta of the super-dense-core (SDC) plasma in the large helical device (LHD) is limited by a large scale MHD event called ‘core density collapse’ (CDC). The detailed measurement reveals that a new type of ballooning mode, quite localized in space and destabilized from the 3D nature of Heliotron devices, is the cause of the CDC. It is the first observation of an unstable mode in a region with global negative magnetic shear. Avoidance of the excitation of this mode is a key to expand the operational limit of the LHD.

Nuclear quantum dynamics in dense hydrogen

PubMed Central

Kang, Dongdong; Sun, Huayang; Dai, Jiayu; Chen, Wenbo; Zhao, Zengxiu; Hou, Yong; Zeng, Jiaolong; Yuan, Jianmin

2014-01-01

Nuclear dynamics in dense hydrogen, which is determined by the key physics of large-angle scattering or many-body collisions between particles, is crucial for the dynamics of planet's evolution and hydrodynamical processes in inertial confinement confusion. Here, using improved ab initio path-integral molecular dynamics simulations, we investigated the nuclear quantum dynamics regarding transport behaviors of dense hydrogen up to the temperatures of 1 eV. With the inclusion of nuclear quantum effects (NQEs), the ionic diffusions are largely higher than the classical treatment by the magnitude from 20% to 146% as the temperature is decreased from 1 eV to 0.3 eV at 10 g/cm3, meanwhile, electrical and thermal conductivities are significantly lowered. In particular, the ionic diffusion is found much larger than that without NQEs even when both the ionic distributions are the same at 1 eV. The significant quantum delocalization of ions introduces remarkably different scattering cross section between protons compared with classical particle treatments, which explains the large difference of transport properties induced by NQEs. The Stokes-Einstein relation, Wiedemann-Franz law, and isotope effects are re-examined, showing different behaviors in nuclear quantum dynamics. PMID:24968754

Development of the mouse vestibular system in the absence of gravity perception

NASA Technical Reports Server (NTRS)

Smith, Michael; Yuan Wang, Xiang; Wolgemuth, Debra J.; Murashov, Alexander K.

2003-01-01

The tilted mutant mouse, which lacks otoconia in the inner ear, was used to study development of the mouse vestibular system in the absence of gravity perception. Otoconia are dense particles composed of proteins and calcium carbonate crystals suspended in the gelatinous macular membrane. They enhance, and are largely responsible for, sensitivity to gravity. Morphometric analysis of the vestibular ganglion showed that the mutant developed more slowly than the normal controls, both in rate of development and cell number, particularly during the first week of post-natal development. The mutant ganglia also exhibited a reduction of cells during the first 6 days of post-natal development.

Special-purpose computing for dense stellar systems

NASA Astrophysics Data System (ADS)

Makino, Junichiro

2007-08-01

I'll describe the current status of the GRAPE-DR project. The GRAPE-DR is the next-generation hardware for N-body simulation. Unlike the previous GRAPE hardwares, it is programmable SIMD machine with a large number of simple processors integrated into a single chip. The GRAPE-DR chip consists of 512 simple processors and operates at the clock speed of 500 MHz, delivering the theoretical peak speed of 512/226 Gflops (single/double precision). As of August 2006, the first prototype board with the sample chip successfully passed the test we prepared. The full GRAPE-DR system will consist of 4096 chips, reaching the theoretical peak speed of 2 Pflops.

Comparison of Danish dichotomous and BI-RADS classifications of mammographic density.

PubMed

Hodge, Rebecca; Hellmann, Sophie Sell; von Euler-Chelpin, My; Vejborg, Ilse; Andersen, Zorana Jovanovic

2014-06-01

In the Copenhagen mammography screening program from 1991 to 2001, mammographic density was classified either as fatty or mixed/dense. This dichotomous mammographic density classification system is unique internationally, and has not been validated before. To compare the Danish dichotomous mammographic density classification system from 1991 to 2001 with the density BI-RADS classifications, in an attempt to validate the Danish classification system. The study sample consisted of 120 mammograms taken in Copenhagen in 1991-2001, which tested false positive, and which were in 2012 re-assessed and classified according to the BI-RADS classification system. We calculated inter-rater agreement between the Danish dichotomous mammographic classification as fatty or mixed/dense and the four-level BI-RADS classification by the linear weighted Kappa statistic. Of the 120 women, 32 (26.7%) were classified as having fatty and 88 (73.3%) as mixed/dense mammographic density, according to Danish dichotomous classification. According to BI-RADS density classification, 12 (10.0%) women were classified as having predominantly fatty (BI-RADS code 1), 46 (38.3%) as having scattered fibroglandular (BI-RADS code 2), 57 (47.5%) as having heterogeneously dense (BI-RADS 3), and five (4.2%) as having extremely dense (BI-RADS code 4) mammographic density. The inter-rater variability assessed by weighted kappa statistic showed a substantial agreement (0.75). The dichotomous mammographic density classification system utilized in early years of Copenhagen's mammographic screening program (1991-2001) agreed well with the BI-RADS density classification system.

Epidemiological study of air filtration systems for preventing PRRSV infection in large sow herds.

PubMed

Alonso, Carmen; Murtaugh, Michael P; Dee, Scott A; Davies, Peter R

2013-10-01

Porcine reproductive and respiratory syndrome virus (PRRSV) is the most economically significant pathogen in the US swine industry. Aerosol transmission among herds is a major concern in pig dense regions and filtration of incoming air, in combination with standard biosecurity procedures, has been demonstrated to prevent transmission of PRRSV into susceptible herds. To quantify the impact of air filtration on reducing risk of PRRSV outbreaks, we compared the incidence rate of new PRRSV introductions in 20 filtered and 17 non-filtered control sow herds in a swine dense region of North America during a 7 year study period. Events of novel virus introduction were ascertained by phylogenetic analysis of PRRSV ORF5 gene sequences. Putative new viruses were defined as exogenous (introduced) based on ORF5 nucleotide sequence differences compared to previous farm isolates. The influence of sequence difference cut-off values ranging from 2 to 10% on case definition and relative risk were evaluated. Non-filtered farms incurred about 0.5 outbreaks per year, with a seasonal increase in risk in cooler periods. Baseline risk, prior to filtration, in treatment farms was approximately 0.75 per year, approximately 50% higher than in control farms. Air filtration significantly reduced risk of PRRSV introduction events to 0.06-0.22 outbreaks per year, depending on the cut-off values used to classify a virus isolate as new to the herd. Overall, air filtration led to an approximately 80% reduction in risk of introduction of novel PRRSV, indicating that on large sow farms with good biosecurity in swine-dense regions, approximately four-fifths of PRRSV outbreaks may be attributable to aerosol transmission. Copyright © 2013 Elsevier B.V. All rights reserved.

A semi-Lagrangian transport method for kinetic problems with application to dense-to-dilute polydisperse reacting spray flows

NASA Astrophysics Data System (ADS)

Doisneau, François; Arienti, Marco; Oefelein, Joseph C.

2017-01-01

For sprays, as described by a kinetic disperse phase model strongly coupled to the Navier-Stokes equations, the resolution strategy is constrained by accuracy objectives, robustness needs, and the computing architecture. In order to leverage the good properties of the Eulerian formalism, we introduce a deterministic particle-based numerical method to solve transport in physical space, which is simple to adapt to the many types of closures and moment systems. The method is inspired by the semi-Lagrangian schemes, developed for Gas Dynamics. We show how semi-Lagrangian formulations are relevant for a disperse phase far from equilibrium and where the particle-particle coupling barely influences the transport; i.e., when particle pressure is negligible. The particle behavior is indeed close to free streaming. The new method uses the assumption of parcel transport and avoids to compute fluxes and their limiters, which makes it robust. It is a deterministic resolution method so that it does not require efforts on statistical convergence, noise control, or post-processing. All couplings are done among data under the form of Eulerian fields, which allows one to use efficient algorithms and to anticipate the computational load. This makes the method both accurate and efficient in the context of parallel computing. After a complete verification of the new transport method on various academic test cases, we demonstrate the overall strategy's ability to solve a strongly-coupled liquid jet with fine spatial resolution and we apply it to the case of high-fidelity Large Eddy Simulation of a dense spray flow. A fuel spray is simulated after atomization at Diesel engine combustion chamber conditions. The large, parallel, strongly coupled computation proves the efficiency of the method for dense, polydisperse, reacting spray flows.

A semi-Lagrangian transport method for kinetic problems with application to dense-to-dilute polydisperse reacting spray flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doisneau, François, E-mail: fdoisne@sandia.gov; Arienti, Marco, E-mail: marient@sandia.gov; Oefelein, Joseph C., E-mail: oefelei@sandia.gov

For sprays, as described by a kinetic disperse phase model strongly coupled to the Navier–Stokes equations, the resolution strategy is constrained by accuracy objectives, robustness needs, and the computing architecture. In order to leverage the good properties of the Eulerian formalism, we introduce a deterministic particle-based numerical method to solve transport in physical space, which is simple to adapt to the many types of closures and moment systems. The method is inspired by the semi-Lagrangian schemes, developed for Gas Dynamics. We show how semi-Lagrangian formulations are relevant for a disperse phase far from equilibrium and where the particle–particle coupling barelymore » influences the transport; i.e., when particle pressure is negligible. The particle behavior is indeed close to free streaming. The new method uses the assumption of parcel transport and avoids to compute fluxes and their limiters, which makes it robust. It is a deterministic resolution method so that it does not require efforts on statistical convergence, noise control, or post-processing. All couplings are done among data under the form of Eulerian fields, which allows one to use efficient algorithms and to anticipate the computational load. This makes the method both accurate and efficient in the context of parallel computing. After a complete verification of the new transport method on various academic test cases, we demonstrate the overall strategy's ability to solve a strongly-coupled liquid jet with fine spatial resolution and we apply it to the case of high-fidelity Large Eddy Simulation of a dense spray flow. A fuel spray is simulated after atomization at Diesel engine combustion chamber conditions. The large, parallel, strongly coupled computation proves the efficiency of the method for dense, polydisperse, reacting spray flows.« less

Kinetic theory of shear thickening for a moderately dense gas-solid suspension: From discontinuous thickening to continuous thickening

NASA Astrophysics Data System (ADS)

Hayakawa, Hisao; Takada, Satoshi; Garzó, Vicente

2017-10-01

The Enskog kinetic theory for moderately dense gas-solid suspensions under simple shear flow is considered as a model to analyze the rheological properties of the system. The influence of the environmental fluid on solid particles is modeled via a viscous drag force plus a stochastic Langevin-like term. The Enskog equation is solved by means of two independent but complementary routes: (i) Grad's moment method and (ii) event-driven Langevin simulation of hard spheres. Both approaches clearly show that the flow curve (stress-strain rate relation) depends significantly on the volume fraction of the solid particles. In particular, as the density increases, there is a transition from the discontinuous shear thickening (observed in dilute gases) to the continuous shear thickening for denser systems. The comparison between theory and simulations indicates that while the theoretical predictions for the kinetic temperature agree well with simulations for densities φ ≲0.5 , the agreement for the other rheological quantities (the viscosity, the stress ratio, and the normal stress differences) is limited to more moderate densities (φ ≲0.3 ) if the inelasticity during collisions between particles is not large.

Can We Selectively Reduce Appetite for Energy-Dense Foods? An Overview of Pharmacological Strategies for Modification of Food Preference Behavior.

PubMed

Bojanowska, Ewa; Ciosek, Joanna

2016-01-01

Excessive intake of food, especially palatable and energy-dense carbohydrates and fats, is largely responsible for the growing incidence of obesity worldwide. Although there are a number of candidate antiobesity drugs, only a few of them have been proven able to inhibit appetite for palatable foods without the concurrent reduction in regular food consumption. In this review, we discuss the interrelationships between homeostatic and hedonic food intake control mechanisms in promoting overeating with palatable foods and assess the potential usefulness of systemically administered pharmaceuticals that impinge on the endogenous cannabinoid, opioid, aminergic, cholinergic, and peptidergic systems in the modification of food preference behavior. Also, certain dietary supplements with the potency to reduce specifically palatable food intake are presented. Based on human and animal studies, we indicate the most promising therapies and agents that influence the effectiveness of appetite-modifying drugs. It should be stressed, however, that most of the data included in our review come from preclinical studies; therefore, further investigations aimed at confirming the effectiveness and safety of the aforementioned medications in the treatment of obese humans are necessary.

Can We Selectively Reduce Appetite for Energy-Dense Foods? An Overview of Pharmacological Strategies for Modification of Food Preference Behavior

PubMed Central

Bojanowska, Ewa; Ciosek, Joanna

2016-01-01

Excessive intake of food, especially palatable and energy-dense carbohydrates and fats, is largely responsible for the growing incidence of obesity worldwide. Although there are a number of candidate antiobesity drugs, only a few of them have been proven able to inhibit appetite for palatable foods without the concurrent reduction in regular food consumption. In this review, we discuss the interrelationships between homeostatic and hedonic food intake control mechanisms in promoting overeating with palatable foods and assess the potential usefulness of systemically administered pharmaceuticals that impinge on the endogenous cannabinoid, opioid, aminergic, cholinergic, and peptidergic systems in the modification of food preference behavior. Also, certain dietary supplements with the potency to reduce specifically palatable food intake are presented. Based on human and animal studies, we indicate the most promising therapies and agents that influence the effectiveness of appetite-modifying drugs. It should be stressed, however, that most of the data included in our review come from preclinical studies; therefore, further investigations aimed at confirming the effectiveness and safety of the aforementioned medications in the treatment of obese humans are necessary. PMID:26549651

Colliding Laser-Produced Plasmas on LaPD

NASA Astrophysics Data System (ADS)

Collette, Andrew; Gekelman, Walter

2007-11-01

The expansion and interaction of dense plasmas in the presence of a magnetized background plasma is important in many astrophysical processes, among them coronal mass ejections and the many examples of plasma jets from astrophotography. Turbulence is expected to be present in many such configurations. We describe a series of experiments which involve the collision of two dense (initially, n > 10^15cm-3) laser-produced plasmas within an ambient, highly magnetized plasma. The laser-produced plasmas form diamagnetic cavities in which a large percentage of the background magnetic field (600G) has been expelled. First-stage observations using a fast (3ns exposure) camera indicate complicated structure at late times, in addition to coherent corrugated structures on the bubble surfaces. The data hint at the presence of turbulence in the interaction. The second stage of observation consists of direct investigation of the magnetic field using probes. A novel diagnostic system composed of small (300-500 micron) 3-axis differential magnetic field probes in conjunction with a ceramic motor system capable of extremely fine (sub-micron) positioning accuracy is currently under development. An ensemble of magnetic field data from fixed and movable probes makes possible the calculation of the cross-spectral function.

Kinetic theory of shear thickening for a moderately dense gas-solid suspension: From discontinuous thickening to continuous thickening.

PubMed

Hayakawa, Hisao; Takada, Satoshi; Garzó, Vicente

2017-10-01

The Enskog kinetic theory for moderately dense gas-solid suspensions under simple shear flow is considered as a model to analyze the rheological properties of the system. The influence of the environmental fluid on solid particles is modeled via a viscous drag force plus a stochastic Langevin-like term. The Enskog equation is solved by means of two independent but complementary routes: (i) Grad's moment method and (ii) event-driven Langevin simulation of hard spheres. Both approaches clearly show that the flow curve (stress-strain rate relation) depends significantly on the volume fraction of the solid particles. In particular, as the density increases, there is a transition from the discontinuous shear thickening (observed in dilute gases) to the continuous shear thickening for denser systems. The comparison between theory and simulations indicates that while the theoretical predictions for the kinetic temperature agree well with simulations for densities φ≲0.5, the agreement for the other rheological quantities (the viscosity, the stress ratio, and the normal stress differences) is limited to more moderate densities (φ≲0.3) if the inelasticity during collisions between particles is not large.

Effects of Noise and Vibration on the Solid to Liquid Fluidization Transition in Small Dense Granular Systems Under Shear

NASA Astrophysics Data System (ADS)

Melhus, Martin Frederic

2011-07-01

Granular materials exhibit bulk properties that are distinct from conventional solids, liq- uids, and gases, due to the dissipative nature of the inter-granular forces. Understanding the fundamentals of granular materials draws upon and gives insight into many fields at the current frontiers of physics, such as plasticity of solids, fracture and friction, com- plex systems such as colloids, foams and suspensions, and a variety of biological systems. Particulate flows are widespread in geophysics, and are also essential to many industries. Despite the importance of these phenomena, we lack a theoretical model that explains most behaviors of granular materials. Since granular assemblies are highly dissipative, they are often far from mechanical equilibrium, making most classical analyses inappli- cable. A theory for dilute granular systems exists, but for dense granular systems (by far the majority of granular systems in the real world) no comparable theory is accepted. We approach this problem by examining the fluidization, or transition from solid to liquid, in dense granular systems. In this study, the separate effects of random noise and vibration on the static to flowing transition of a dense granular assembly under planar shear is studied numerically using soft contact particle dynamics simulations in two dimensions. We focus on small systems in a thin planar Couette cell, examining the bistable region while increasing shear, with varying amounts of random noise or vibration, and determine the statistics of the shear required for the onset of flow. We find that the applied power is the key parameter in determining the magnitude of the effects of the noise or vibration, with vibration frequency also having an influence. Similarities and differences between noise and vibration are determined, and the results compare favorably with a two phase model for dense granular flow.

A Framework for Real-Time Collection, Analysis, and Classification of Ubiquitous Infrasound Data

NASA Astrophysics Data System (ADS)

Christe, A.; Garces, M. A.; Magana-Zook, S. A.; Schnurr, J. M.

2015-12-01

Traditional infrasound arrays are generally expensive to install and maintain. There are ~10^3 infrasound channels on Earth today. The amount of data currently provided by legacy architectures can be processed on a modest server. However, the growing availability of low-cost, ubiquitous, and dense infrasonic sensor networks presents a substantial increase in the volume, velocity, and variety of data flow. Initial data from a prototype ubiquitous global infrasound network is already pushing the boundaries of traditional research server and communication systems, in particular when serving data products over heterogeneous, international network topologies. We present a scalable, cloud-based approach for capturing and analyzing large amounts of dense infrasonic data (>10^6 channels). We utilize Akka actors with WebSockets to maintain data connections with infrasound sensors. Apache Spark provides streaming, batch, machine learning, and graph processing libraries which will permit signature classification, cross-correlation, and other analytics in near real time. This new framework and approach provide significant advantages in scalability and cost.

A frictionally and hydraulically constrained model of the convectively driven mean flow in partially enclosed seas

NASA Astrophysics Data System (ADS)

Maxworthy, T.

1997-08-01

A simple three-layer model of the dynamics of partially enclosed seas, driven by a surface buoyancy flux, is presented. It contains two major elements, a hydraulic constraint at the exit contraction and friction in the interior of the main body of the sea; both together determine the vertical structure and magnitudes of the interior flow variables, i.e. velocity and density. Application of the model to the large-scale dynamics of the Red Sea gives results that are not in disagreement with observation once the model is applied, also, to predict the dense outflow from the Gulf of Suez. The latter appears to be the agent responsible for the formation of dense bottom water in this system. Also, the model is reasonably successful in predicting the density of the outflow from the Persian Gulf, and can be applied to any number of other examples of convectively driven flow in long, narrow channels, with or without sills and constrictions at their exits.

Integration of prior knowledge into dense image matching for video surveillance

NASA Astrophysics Data System (ADS)

Menze, M.; Heipke, C.

2014-08-01

Three-dimensional information from dense image matching is a valuable input for a broad range of vision applications. While reliable approaches exist for dedicated stereo setups they do not easily generalize to more challenging camera configurations. In the context of video surveillance the typically large spatial extent of the region of interest and repetitive structures in the scene render the application of dense image matching a challenging task. In this paper we present an approach that derives strong prior knowledge from a planar approximation of the scene. This information is integrated into a graph-cut based image matching framework that treats the assignment of optimal disparity values as a labelling task. Introducing the planar prior heavily reduces ambiguities together with the search space and increases computational efficiency. The results provide a proof of concept of the proposed approach. It allows the reconstruction of dense point clouds in more general surveillance camera setups with wider stereo baselines.

Enhanced Mobility in Concentrated Pyroclastic Density Currents: An Examination of a Self-Fluidization Mechanism

NASA Astrophysics Data System (ADS)

Breard, Eric C. P.; Dufek, Josef; Lube, Gert

2018-01-01

Pyroclastic density currents (PDCs) are a significant volcanic hazard. However, their dominant transport mechanisms remain poorly understood, in part because of the large variability of PDC types and deposits. Here we combine field data with experimental and numerical simulations to illuminate the twofold fate of particles settling from an ash cloud to form the dense PDC basal flow. At solid fractions >1 vol %, heterogeneous drag leads to formation of mesoscale particle clusters that favor rapid particle settling and result in a mobile dense layer with significant bed weight support. Conversely, at lower concentrations the absence of particle clusters typically leads to formation of poorly mobile dense beds that deposit massive layers. Based on this transport dichotomy, we present a numerical dense-dilute parameter that allows a PDC's dominant transport mechanism to be determined directly from the deposit geometry and grainsize characteristics.

Electrostatic analogy for symmetron gravity

NASA Astrophysics Data System (ADS)

Ogden, Lillie; Brown, Katherine; Mathur, Harsh; Rovelli, Kevin

2017-12-01

The symmetron model is a scalar-tensor theory of gravity with a screening mechanism that suppresses the effect of the symmetron field at high densities characteristic of the Solar System and laboratory scales but allows it to act with gravitational strength at low density on the cosmological scale. We elucidate the screening mechanism by showing that in the quasistatic Newtonian limit there are precise analogies between symmetron gravity and electrostatics for both strong and weak screening. For strong screening we find that large dense bodies behave in a manner analogous to perfect conductors in electrostatics. Based on this analogy we find that the symmetron field exhibits a lightning rod effect wherein the field gradients are enhanced near the ends of pointed or elongated objects. An ellipsoid placed in a uniform symmetron gradient is shown to experience a torque. By symmetry there is no gravitational torque in this case. Hence this effect unmasks the symmetron and might serve as the basis for future laboratory experiments. The symmetron force between a point mass and a large dense body includes a component corresponding to the interaction of the point mass with its image in the larger body. None of these effects have counterparts in the Newtonian limit of Einstein gravity. We discuss the similarities between symmetron gravity and the chameleon model as well as the differences between the two.

Integration and Analysis of Neighbor Discovery and Link Quality Estimation in Wireless Sensor Networks

PubMed Central

Radi, Marjan; Dezfouli, Behnam; Abu Bakar, Kamalrulnizam; Abd Razak, Shukor

2014-01-01

Network connectivity and link quality information are the fundamental requirements of wireless sensor network protocols to perform their desired functionality. Most of the existing discovery protocols have only focused on the neighbor discovery problem, while a few number of them provide an integrated neighbor search and link estimation. As these protocols require a careful parameter adjustment before network deployment, they cannot provide scalable and accurate network initialization in large-scale dense wireless sensor networks with random topology. Furthermore, performance of these protocols has not entirely been evaluated yet. In this paper, we perform a comprehensive simulation study on the efficiency of employing adaptive protocols compared to the existing nonadaptive protocols for initializing sensor networks with random topology. In this regard, we propose adaptive network initialization protocols which integrate the initial neighbor discovery with link quality estimation process to initialize large-scale dense wireless sensor networks without requiring any parameter adjustment before network deployment. To the best of our knowledge, this work is the first attempt to provide a detailed simulation study on the performance of integrated neighbor discovery and link quality estimation protocols for initializing sensor networks. This study can help system designers to determine the most appropriate approach for different applications. PMID:24678277

Petrologic constraints on the decompression history of magma prior to Vulcanian explosions at the Soufrière Hills volcano, Montserrat

NASA Astrophysics Data System (ADS)

Clarke, A. B.; Stephens, S.; Teasdale, R.; Sparks, R. S. J.; Diller, K.

2007-04-01

A series of 88 Vulcanian explosions occurred at the Soufrière Hills volcano, Montserrat, between August and October, 1997. Conduit conditions conducive to creating these and other Vulcanian explosions were explored via analysis of eruptive products and one-dimensional numerical modeling of magma ascent through a cylindrical conduit. The number densities and textures of plagioclase microlites were documented for twenty-three samples from the events. The natural samples all show very high number densities of microlites, and > 50% by number of microlites have areas < 20 μm 2. Pre-explosion conduit conditions and decompression history have been inferred from these data by comparison with experimental decompressions of similar groundmass compositions. Our comparisons suggest quench pressures < 30 MPa (origin depths < 2 km) and multiple rapid decompressions of > 13.75 MPa each during ascent from chamber to surface. Values are consistent with field studies of the same events and statistical analysis of explosion time-series data. The microlite volume number density trend with depth reveals an apparent transition from growth-dominated crystallization to nucleation-dominated crystallization at pressures of ˜ 7 MPa and lower. A concurrent sharp increase in bulk density marks the onset of significant open-system degassing, apparently due to a large increase in system permeability above ˜ 70% vesicularity. This open-system degassing results in a dense plug which eventually seals the conduit and forms conditions favorable to Vulcanian explosions. The corresponding inferred depth of overpressure at 250-700 m, near the base of the dense plug, is consistent with depth to center of pressure estimated from deformation measurements. Here we also illustrate that one-dimensional models representing ascent of a degassing, crystal-rich magma are broadly consistent with conduit profiles constructed via our petrologic analysis. The comparison between models and petrologic data suggests that the dense conduit plug forms as a result of high overpressure and open-system degassing through conduit walls.

Point cloud generation from aerial image data acquired by a quadrocopter type micro unmanned aerial vehicle and a digital still camera.

PubMed

Rosnell, Tomi; Honkavaara, Eija

2012-01-01

The objective of this investigation was to develop and investigate methods for point cloud generation by image matching using aerial image data collected by quadrocopter type micro unmanned aerial vehicle (UAV) imaging systems. Automatic generation of high-quality, dense point clouds from digital images by image matching is a recent, cutting-edge step forward in digital photogrammetric technology. The major components of the system for point cloud generation are a UAV imaging system, an image data collection process using high image overlaps, and post-processing with image orientation and point cloud generation. Two post-processing approaches were developed: one of the methods is based on Bae Systems' SOCET SET classical commercial photogrammetric software and another is built using Microsoft(®)'s Photosynth™ service available in the Internet. Empirical testing was carried out in two test areas. Photosynth processing showed that it is possible to orient the images and generate point clouds fully automatically without any a priori orientation information or interactive work. The photogrammetric processing line provided dense and accurate point clouds that followed the theoretical principles of photogrammetry, but also some artifacts were detected. The point clouds from the Photosynth processing were sparser and noisier, which is to a large extent due to the fact that the method is not optimized for dense point cloud generation. Careful photogrammetric processing with self-calibration is required to achieve the highest accuracy. Our results demonstrate the high performance potential of the approach and that with rigorous processing it is possible to reach results that are consistent with theory. We also point out several further research topics. Based on theoretical and empirical results, we give recommendations for properties of imaging sensor, data collection and processing of UAV image data to ensure accurate point cloud generation.

Energy transfer dynamics in strongly inhomogeneous hot-dense-matter systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stillman, C. R.; Nilson, P. M.; Sefkow, A. B.

Direct measurements of energy transfer across steep density and temperature gradients in a hot-dense-matter system are presented. Hot dense plasma conditions were generated by high-intensity laser irradiation of a thin-foil target containing a buried metal layer. Energy transfer to the layer was measured using picosecond time-resolved x-ray emission spectroscopy. Here, the data show two x-ray flashes in time. Fully explicit, coupled particle-in-cell and collisional-radiative atomic kinetics model predictions reproduce these observations, connecting the two x-ray flashes with staged radial energy transfer within the target.

Energy transfer dynamics in strongly inhomogeneous hot-dense-matter systems

DOE PAGES

Stillman, C. R.; Nilson, P. M.; Sefkow, A. B.; ...

2018-06-25

Direct measurements of energy transfer across steep density and temperature gradients in a hot-dense-matter system are presented. Hot dense plasma conditions were generated by high-intensity laser irradiation of a thin-foil target containing a buried metal layer. Energy transfer to the layer was measured using picosecond time-resolved x-ray emission spectroscopy. Here, the data show two x-ray flashes in time. Fully explicit, coupled particle-in-cell and collisional-radiative atomic kinetics model predictions reproduce these observations, connecting the two x-ray flashes with staged radial energy transfer within the target.

Large-scale imaging in small brains

PubMed Central

Ahrens, Misha B.; Engert, Florian

2016-01-01

The dense connectivity in the brain and arrangements of cells into circuits means that one neuron’s activity can influence many others. To observe this interconnected system comprehensively, an aspiration within neuroscience is to record from as many neurons as possible at the same time. There are two useful routes toward this goal: one is to expand the spatial extent of functional imaging techniques, and the second is to use animals with small brains. Here we review recent progress toward imaging many neurons and complete populations of identified neurons in small vertebrates and invertebrates. PMID:25636154

Large-scale imaging in small brains.

PubMed

Ahrens, Misha B; Engert, Florian

2015-06-01

The dense connectivity in the brain means that one neuron's activity can influence many others. To observe this interconnected system comprehensively, an aspiration within neuroscience is to record from as many neurons as possible at the same time. There are two useful routes toward this goal: one is to expand the spatial extent of functional imaging techniques, and the second is to use animals with small brains. Here we review recent progress toward imaging many neurons and complete populations of identified neurons in small vertebrates and invertebrates. Copyright © 2015 Elsevier Ltd. All rights reserved.

Activity statistics in a colloidal glass former: Experimental evidence for a dynamical transition

NASA Astrophysics Data System (ADS)

Abou, Bérengère; Colin, Rémy; Lecomte, Vivien; Pitard, Estelle; van Wijland, Frédéric

2018-04-01

In a dense colloidal suspension at a volume fraction below the glass transition, we follow the trajectories of an assembly of tracers over a large time window. We define a local activity, which quantifies the local tendency of the system to rearrange. We determine the statistics of the time integrated activity, and we argue that it develops a low activity tail that comes together with the onset of glassy-like behavior and heterogeneous dynamics. These rare events may be interpreted as the reflection of an underlying dynamic phase transition.

Effects of the bottom boundary condition in numerical investigations of dense water cascading on a slope

NASA Astrophysics Data System (ADS)

Berntsen, Jarle; Alendal, Guttorm; Avlesen, Helge; Thiem, Øyvind

2018-05-01

The flow of dense water along continental slopes is considered. There is a large literature on the topic based on observations and laboratory experiments. In addition, there are many analytical and numerical studies of dense water flows. In particular, there is a sequence of numerical investigations using the dynamics of overflow mixing and entrainment (DOME) setup. In these papers, the sensitivity of the solutions to numerical parameters such as grid size and numerical viscosity coefficients and to the choices of methods and models is investigated. In earlier DOME studies, three different bottom boundary conditions and a range of vertical grid sizes are applied. In other parts of the literature on numerical studies of oceanic gravity currents, there are statements that appear to contradict choices made on bottom boundary conditions in some of the DOME papers. In the present study, we therefore address the effects of the bottom boundary condition and vertical resolution in numerical investigations of dense water cascading on a slope. The main finding of the present paper is that it is feasible to capture the bottom Ekman layer dynamics adequately and cost efficiently by using a terrain-following model system using a quadratic drag law with a drag coefficient computed to give near-bottom velocity profiles in agreement with the logarithmic law of the wall. Many studies of dense water flows are performed with a quadratic bottom drag law and a constant drag coefficient. It is shown that when using this bottom boundary condition, Ekman drainage will not be adequately represented. In other studies of gravity flow, a no-slip bottom boundary condition is applied. With no-slip and a very fine resolution near the seabed, the solutions are essentially equal to the solutions obtained with a quadratic drag law and a drag coefficient computed to produce velocity profiles matching the logarithmic law of the wall. However, with coarser resolution near the seabed, there may be a substantial artificial blocking effect when using no-slip.

Cytochemical study of the nucleolus of the slime mold Dictyostelium discoideum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benichou, J.C.; Quiviger, B.; Ryter, A.

1983-07-01

The nucleus of the slime mold Dictyostelium discoideum is characterized by the presence of several large dense masses which are all in tight contact with the nuclear membrane. These dense masses, considered as nucleoli, present a rather homogeneous texture, in which dense chromatin, fibrillar, and granular material are not easily detected. The autoradiographic study of (/sup 3/H)uridine pulse-labeled cells showed that the majority of the silver grains were located inside these masses. The use of EDTA regressive-staining, acetylation and enzymatic digestion indicated that they are mostly composed of RNP and are totally devoid of dense chromatin as the rest ofmore » the nucleus is. After treatment with actinomycin D, fibrillar and granular material segregated but no chromatin could be found. All these observations confirmed that the dense masses correspond to nucleoli despite their peculiar ultrastructure. It can also be concluded that this type of nucleoli cannot be considered as a taxonomic character of the slime molds because it does not exist in all slime molds and was observed in some dinoflagellates, and ascomycetes.« less

Urban water - a new frontier in isotope hydrology.

PubMed

Ehleringer, James R; Barnette, Janet E; Jameel, Yusuf; Tipple, Brett J; Bowen, Gabriel J

2016-01-01

Isotope hydrology has focused largely on landscapes away from densely inhabited regions. In coming decades, it will become increasingly more important to focus on water supplies and dynamics within urban systems. Stable isotope analyses provide important information to water managers within large cities, particularly in arid regions where evaporative histories of water sources, vulnerabilities, and reliabilities of the water supplies can be major issues. Here the spatial and vertical understanding of water supporting urban systems that comes from stable isotope analyses can serve as a useful management tool. We explore this research frontier using the coupled natural-human landscape of the Salt Lake Valley, USA, with its greater than one million inhabitants. We first provide data on the stable isotope ratios of the hydrologic system's primary components: precipitation, incoming surface waters, and terminus waters in this closed basin. We then explore the spatial and temporal patterns of drinking waters within the urban landscape and the new opportunities to better link isotope ratio data with short- and long-term management interests of water managers.

Dense Chern-Simons matter with fermions at large N

NASA Astrophysics Data System (ADS)

Geracie, Michael; Goykhman, Mikhail; Son, Dam T.

2016-04-01

In this paper we investigate properties of Chern-Simons theory coupled to massive fermions in the large N limit. We demonstrate that at low temperatures the system is in a Fermi liquid state whose features can be systematically compared to the standard phenomenological theory of Landau Fermi liquids. This includes matching microscopically derived Landau parameters with thermodynamic predictions of Landau Fermi liquid theory. We also calculate the exact conductivity and viscosity tensors at zero temperature and finite chemical potential. In particular we point out that the Hall conductivity of an interacting system is not entirely accounted for by the Berry flux through the Fermi sphere. Furthermore, investigation of the thermodynamics in the non-relativistic limit reveals novel phenomena at strong coupling. As the 't Hooft coupling λ approaches 1, the system exhibits an extended intermediate temperature regime in which the thermodynamics is described by neither the quantum Fermi liquid theory nor the classical ideal gas law. Instead, it can be interpreted as a weakly coupled quantum Bose gas.

Large scale, highly dense nanoholes on metal surfaces by underwater laser assisted hydrogen etching near nanocrystalline boundary

NASA Astrophysics Data System (ADS)

Lin, Dong; Zhang, Martin Yi; Ye, Chang; Liu, Zhikun; Liu, C. Richard; Cheng, Gary J.

2012-03-01

A new method to generate large scale and highly dense nanoholes is presented in this paper. By the pulsed laser irradiation under water, the hydrogen etching is introduced to form high density nanoholes on the surfaces of AISI 4140 steel and Ti. In order to achieve higher nanohole density, laser shock peening (LSP) followed by recrystallization is used for grain refinement. It is found that the nanohole density does not increase until recrystallization of the substructures after laser shock peening. The mechanism of nanohole generation is studied in detail. This method can be also applied to generate nanoholes on other materials with hydrogen etching effect.

Single-shot mega-electronvolt ultrafast electron diffraction for structure dynamic studies of warm dense matter

NASA Astrophysics Data System (ADS)

Mo, M. Z.; Shen, X.; Chen, Z.; Li, R. K.; Dunning, M.; Sokolowski-Tinten, K.; Zheng, Q.; Weathersby, S. P.; Reid, A. H.; Coffee, R.; Makasyuk, I.; Edstrom, S.; McCormick, D.; Jobe, K.; Hast, C.; Glenzer, S. H.; Wang, X.

2016-11-01

We have developed a single-shot mega-electronvolt ultrafast-electron-diffraction system to measure the structural dynamics of warm dense matter. The electron probe in this system is featured by a kinetic energy of 3.2 MeV and a total charge of 20 fC, with the FWHM pulse duration and spot size at sample of 350 fs and 120 μm respectively. We demonstrate its unique capability by visualizing the atomic structural changes of warm dense gold formed from a laser-excited 35-nm freestanding single-crystal gold foil. The temporal evolution of the Bragg peak intensity and of the liquid signal during solid-liquid phase transition are quantitatively determined. This experimental capability opens up an exciting opportunity to unravel the atomic dynamics of structural phase transitions in warm dense matter regime.

Dense water plumes modulate richness and productivity of deep sea microbes.

PubMed

Luna, Gian Marco; Chiggiato, Jacopo; Quero, Grazia Marina; Schroeder, Katrin; Bongiorni, Lucia; Kalenitchenko, Dimitri; Galand, Pierre E

2016-12-01

Growing evidence indicates that dense water formation and flow over the continental shelf is a globally relevant oceanographic process, potentially affecting microbial assemblages down to the deep ocean. However, the extent and consequences of this influence have yet to be investigated. Here it is shown that dense water propagation to the deep ocean increases the abundance of prokaryotic plankton, and stimulates carbon production and organic matter degradation rates. Dense waters spilling off the shelf modifies community composition of deep sea microbial assemblages, leading to the increased relevance of taxa likely originating from the sea surface and the seafloor. This phenomenon can be explained by a combination of factors that interplay during the dense waters propagation, such as the transport of surface microbes to the ocean floor (delivering in our site 0.1 megatons of C), the stimulation of microbial metabolism due to increased ventilation and nutrients availability, the sediment re-suspension, and the mixing with ambient waters along the path. Thus, these results highlight a hitherto unidentified role for dense currents flowing over continental shelves in influencing deep sea microbes. In light of climate projections, this process will affect significantly the microbial functioning and biogeochemical cycling of large sectors of the ocean interior. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Organization of testicular interstitial tissue of an Australian rodent, the spinifex hopping mouse, Notomys alexis.

PubMed

Peirce, E J; Breed, W G

1990-05-01

The organization of testicular interstitial tissue of the spinifex hopping mouse, Notomys alexis differs from that of other rodents. It comprises between 10.3% and 17.3% (average 15.0%) of the total testicular volume, and is variable in its organization both at different locations within the testis of the one animal and among different individuals. Abundant, closely packed Leydig cells are usually present; however, in some regions large, thick-walled blood vessels and extensive peritubular lymphatic spaces, often lacking an endothelium adjacent to the Leydig cells, are also prominent. The Leydig cells in contact with the large blood vessels and lymphatics, unlike those in regions where lymph is sparse, are not densely packed and sometimes contain numerous lipid droplets. Ultrastructure of Leydig cells is typical of steroid-producing cells; however, mitochondria are often extremely large, unusual in shape or bizarrely arranged in relation to one another. Also electron-dense bodies displaying a paracrystalline-like internal structure of parallel, electron-dense filaments arranged in a lattice pattern occur in the cytoplasm of many cells. The significance of these unusual ultrastructural features and the organization of the interstitial tissue remain to be determined conclusively, but may relate to steroid synthesis, secretion and uptake.

Efficient Implementation of an Optimal Interpolator for Large Spatial Data Sets

NASA Technical Reports Server (NTRS)

Memarsadeghi, Nargess; Mount, David M.

2007-01-01

Scattered data interpolation is a problem of interest in numerous areas such as electronic imaging, smooth surface modeling, and computational geometry. Our motivation arises from applications in geology and mining, which often involve large scattered data sets and a demand for high accuracy. The method of choice is ordinary kriging. This is because it is a best unbiased estimator. Unfortunately, this interpolant is computationally very expensive to compute exactly. For n scattered data points, computing the value of a single interpolant involves solving a dense linear system of size roughly n x n. This is infeasible for large n. In practice, kriging is solved approximately by local approaches that are based on considering only a relatively small'number of points that lie close to the query point. There are many problems with this local approach, however. The first is that determining the proper neighborhood size is tricky, and is usually solved by ad hoc methods such as selecting a fixed number of nearest neighbors or all the points lying within a fixed radius. Such fixed neighborhood sizes may not work well for all query points, depending on local density of the point distribution. Local methods also suffer from the problem that the resulting interpolant is not continuous. Meyer showed that while kriging produces smooth continues surfaces, it has zero order continuity along its borders. Thus, at interface boundaries where the neighborhood changes, the interpolant behaves discontinuously. Therefore, it is important to consider and solve the global system for each interpolant. However, solving such large dense systems for each query point is impractical. Recently a more principled approach to approximating kriging has been proposed based on a technique called covariance tapering. The problems arise from the fact that the covariance functions that are used in kriging have global support. Our implementations combine, utilize, and enhance a number of different approaches that have been introduced in literature for solving large linear systems for interpolation of scattered data points. For very large systems, exact methods such as Gaussian elimination are impractical since they require 0(n(exp 3)) time and 0(n(exp 2)) storage. As Billings et al. suggested, we use an iterative approach. In particular, we use the SYMMLQ method, for solving the large but sparse ordinary kriging systems that result from tapering. The main technical issue that need to be overcome in our algorithmic solution is that the points' covariance matrix for kriging should be symmetric positive definite. The goal of tapering is to obtain a sparse approximate representation of the covariance matrix while maintaining its positive definiteness. Furrer et al. used tapering to obtain a sparse linear system of the form Ax = b, where A is the tapered symmetric positive definite covariance matrix. Thus, Cholesky factorization could be used to solve their linear systems. They implemented an efficient sparse Cholesky decomposition method. They also showed if these tapers are used for a limited class of covariance models, the solution of the system converges to the solution of the original system. Matrix A in the ordinary kriging system, while symmetric, is not positive definite. Thus, their approach is not applicable to the ordinary kriging system. Therefore, we use tapering only to obtain a sparse linear system. Then, we use SYMMLQ to solve the ordinary kriging system. We show that solving large kriging systems becomes practical via tapering and iterative methods, and results in lower estimation errors compared to traditional local approaches, and significant memory savings compared to the original global system. We also developed a more efficient variant of the sparse SYMMLQ method for large ordinary kriging systems. This approach adaptively finds the correct local neighborhood for each query point in the interpolation process.

Vortex dynamics and Lagrangian statistics in a model for active turbulence.

PubMed

James, Martin; Wilczek, Michael

2018-02-14

Cellular suspensions such as dense bacterial flows exhibit a turbulence-like phase under certain conditions. We study this phenomenon of "active turbulence" statistically by using numerical tools. Following Wensink et al. (Proc. Natl. Acad. Sci. U.S.A. 109, 14308 (2012)), we model active turbulence by means of a generalized Navier-Stokes equation. Two-point velocity statistics of active turbulence, both in the Eulerian and the Lagrangian frame, is explored. We characterize the scale-dependent features of two-point statistics in this system. Furthermore, we extend this statistical study with measurements of vortex dynamics in this system. Our observations suggest that the large-scale statistics of active turbulence is close to Gaussian with sub-Gaussian tails.

Efficient sparse matrix-matrix multiplication for computing periodic responses by shooting method on Intel Xeon Phi

NASA Astrophysics Data System (ADS)

Stoykov, S.; Atanassov, E.; Margenov, S.

2016-10-01

Many of the scientific applications involve sparse or dense matrix operations, such as solving linear systems, matrix-matrix products, eigensolvers, etc. In what concerns structural nonlinear dynamics, the computations of periodic responses and the determination of stability of the solution are of primary interest. Shooting method iswidely used for obtaining periodic responses of nonlinear systems. The method involves simultaneously operations with sparse and dense matrices. One of the computationally expensive operations in the method is multiplication of sparse by dense matrices. In the current work, a new algorithm for sparse matrix by dense matrix products is presented. The algorithm takes into account the structure of the sparse matrix, which is obtained by space discretization of the nonlinear Mindlin's plate equation of motion by the finite element method. The algorithm is developed to use the vector engine of Intel Xeon Phi coprocessors. It is compared with the standard sparse matrix by dense matrix algorithm and the one developed by Intel MKL and it is shown that by considering the properties of the sparse matrix better algorithms can be developed.

Terrain Classification and Identification of Tree Stems Using Ground-Based Lidar

DTIC Science & Technology

2012-12-01

hailing from North America and Eastern Asia. Stands are mixed age and very diverse, making this an appealing test site in terms of tree variety...sparse scene in Fig. 3(b) contains several deciduous trees and shrubs, but is largely open. The moderate scene, shown in Fig. 3(c), is cluttered with...numerous deciduous trees and shrubs, and significant ground cover. The remaining two data sets, dense1 and dense2 were collected at Breakheart

An automated method for finding molecular complexes in large protein interaction networks

PubMed Central

Bader, Gary D; Hogue, Christopher WV

2003-01-01

Background Recent advances in proteomics technologies such as two-hybrid, phage display and mass spectrometry have enabled us to create a detailed map of biomolecular interaction networks. Initial mapping efforts have already produced a wealth of data. As the size of the interaction set increases, databases and computational methods will be required to store, visualize and analyze the information in order to effectively aid in knowledge discovery. Results This paper describes a novel graph theoretic clustering algorithm, "Molecular Complex Detection" (MCODE), that detects densely connected regions in large protein-protein interaction networks that may represent molecular complexes. The method is based on vertex weighting by local neighborhood density and outward traversal from a locally dense seed protein to isolate the dense regions according to given parameters. The algorithm has the advantage over other graph clustering methods of having a directed mode that allows fine-tuning of clusters of interest without considering the rest of the network and allows examination of cluster interconnectivity, which is relevant for protein networks. Protein interaction and complex information from the yeast Saccharomyces cerevisiae was used for evaluation. Conclusion Dense regions of protein interaction networks can be found, based solely on connectivity data, many of which correspond to known protein complexes. The algorithm is not affected by a known high rate of false positives in data from high-throughput interaction techniques. The program is available from . PMID:12525261

Quantum molecular dynamics simulations of dense matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, L.; Kress, J.; Troullier, N.

1997-12-31

The authors have developed a quantum molecular dynamics (QMD) simulation method for investigating the properties of dense matter in a variety of environments. The technique treats a periodically-replicated reference cell containing N atoms in which the nuclei move according to the classical equations-of-motion. The interatomic forces are generated from the quantum mechanical interactions of the (between?) electrons and nuclei. To generate these forces, the authors employ several methods of varying sophistication from the tight-binding (TB) to elaborate density functional (DF) schemes. In the latter case, lengthy simulations on the order of 200 atoms are routinely performed, while for the TB,more » which requires no self-consistency, upwards to 1000 atoms are systematically treated. The QMD method has been applied to a variety cases: (1) fluid/plasma Hydrogen from liquid density to 20 times volume-compressed for temperatures of a thousand to a million degrees Kelvin; (2) isotopic hydrogenic mixtures, (3) liquid metals (Li, Na, K); (4) impurities such as Argon in dense hydrogen plasmas; and (5) metal/insulator transitions in rare gas systems (Ar,Kr) under high compressions. The advent of parallel versions of the methods, especially for fast eigensolvers, presage LDA simulations in the range of 500--1000 atoms and TB runs for tens of thousands of particles. This leap should allow treatment of shock chemistry as well as large-scale mixtures of species in highly transient environments.« less

Experimental Investigation on the Basic Law of Directional Hydraulic Fracturing Controlled by Dense Linear Multi-Hole Drilling

NASA Astrophysics Data System (ADS)

Zhao, Xinglong; Huang, Bingxiang; Wang, Zhen

2018-06-01

Directional rupture is a significant and routine problem for ground control in mines. Directional hydraulic fracturing controlled by dense linear multi-hole drilling was proposed. The physical model experiment, performed by the large-scale true triaxial hydraulic fracturing experimental system, aims to investigate the basic law of directional hydraulic fracturing controlled by dense linear multi-hole drilling, the impact of three different pumping modes on the initiation and propagation of hydraulic fractures among boreholes are particular investigated. The experimental results indicated that there are mutual impacts among different boreholes during crack propagation, which leads to a trend of fracture connection. Furthermore, during propagation, the fractures not only exhibit an overall bias toward the direction in which the boreholes are scattered but also partially offset against the borehole axes and intersect. The directional fracturing effect of equivalent pumping rate in each borehole is better than the other two pumping modes. In practical applications, because of rock mass heterogeneity, there may be differences in terms of filtration rate and effective input volume in different boreholes; thus, water pressure increase and rupture are not simultaneous in different boreholes. Additionally, if the crack initiation directions of different boreholes at different times are not consistent with each other, more lamellar failure planes will occur, and the mutual influences of these lamellar failure planes cause fractures to extend and intersect.

Numerically Exact Computer Simulations of Light Scattering by Densely Packed, Random Particulate Media

NASA Technical Reports Server (NTRS)

Dlugach, Janna M.; Mishchenko, Michael I.; Liu, Li; Mackowski, Daniel W.

2011-01-01

Direct computer simulations of electromagnetic scattering by discrete random media have become an active area of research. In this progress review, we summarize and analyze our main results obtained by means of numerically exact computer solutions of the macroscopic Maxwell equations. We consider finite scattering volumes with size parameters in the range, composed of varying numbers of randomly distributed particles with different refractive indices. The main objective of our analysis is to examine whether all backscattering effects predicted by the low-density theory of coherent backscattering (CB) also take place in the case of densely packed media. Based on our extensive numerical data we arrive at the following conclusions: (i) all backscattering effects predicted by the asymptotic theory of CB can also take place in the case of densely packed media; (ii) in the case of very large particle packing density, scattering characteristics of discrete random media can exhibit behavior not predicted by the low-density theories of CB and radiative transfer; (iii) increasing the absorptivity of the constituent particles can either enhance or suppress typical manifestations of CB depending on the particle packing density and the real part of the refractive index. Our numerical data strongly suggest that spectacular backscattering effects identified in laboratory experiments and observed for a class of high-albedo Solar System objects are caused by CB.

The Dense Molecular Gas and Nuclear Activity in the ULIRG IRAS 13120-5453

NASA Astrophysics Data System (ADS)

Privon, G. C.; Aalto, S.; Falstad, N.; Muller, S.; González-Alfonso, E.; Sliwa, K.; Treister, E.; Costagliola, F.; Armus, L.; Evans, A. S.; Garcia-Burillo, S.; Izumi, T.; Sakamoto, K.; van der Werf, P.; Chu, J. K.

2017-02-01

We present new Atacama Large Millimeter/submillimeter Array Band 7 (˜340 GHz) observations of the dense gas tracers HCN, HCO+, and CS in the local, single-nucleus, ultraluminous infrared galaxy IRAS 13120-5453. We find centrally enhanced HCN (4-3) emission, relative to HCO+ (4-3), but do not find evidence for radiative pumping of HCN. Considering the size of the starburst (0.5 kpc) and the estimated supernovae rate of ˜1.2 yr-1, the high HCN/HCO+ ratio can be explained by an enhanced HCN abundance as a result of mechanical heating by the supernovae, though the active galactic nucleus and winds may also contribute additional mechanical heating. The starburst size implies a high ΣIR of 4.7 × 1012 L ⊙ kpc-2, slightly below predictions of radiation-pressure limited starbursts. The HCN line profile has low-level wings, which we tentatively interpret as evidence for outflowing dense molecular gas. However, the dense molecular outflow seen in the HCN line wings is unlikely to escape the Galaxy and is destined to return to the nucleus and fuel future star formation. We also present modeling of Herschel observations of the H2O lines and find a nuclear dust temperature of ˜40 K. IRAS 13120-5453 has a lower dust temperature and ΣIR than is inferred for the systems termed “compact obscured nuclei (CONs)” (such as Arp 220 and Mrk 231). If IRAS 13120-5453 has undergone a CON phase, we are likely witnessing it at a time when the feedback has already inflated the nuclear ISM and diluted star formation in the starburst/active galactic nucleus core.

Investigation of Alien Wavelength Quality in Live Multi-Domain, Multi-Vendor Link Using Advanced Simulation Tool

NASA Astrophysics Data System (ADS)

Nordal Petersen, Martin; Nuijts, Roeland; Lange Bjørn, Lars

2014-05-01

This article presents an advanced optical model for simulation of alien wavelengths in multi-domain and multi-vendor dense wavelength-division multiplexing networks. The model aids optical network planners with a better understanding of the non-linear effects present in dense wavelength-division multiplexing systems and better utilization of alien wavelengths in future applications. The limiting physical effects for alien wavelengths are investigated in relation to power levels, channel spacing, and other factors. The simulation results are verified through experimental setup in live multi-domain dense wavelength-division multiplexing systems between two national research networks: SURFnet in Holland and NORDUnet in Denmark.

Performance optimization of dense-array concentrator photovoltaic system considering effects of circumsolar radiation and slope error.

PubMed

Wong, Chee-Woon; Chong, Kok-Keong; Tan, Ming-Hui

2015-07-27

This paper presents an approach to optimize the electrical performance of dense-array concentrator photovoltaic system comprised of non-imaging dish concentrator by considering the circumsolar radiation and slope error effects. Based on the simulated flux distribution, a systematic methodology to optimize the layout configuration of solar cells interconnection circuit in dense array concentrator photovoltaic module has been proposed by minimizing the current mismatch caused by non-uniformity of concentrated sunlight. An optimized layout of interconnection solar cells circuit with minimum electrical power loss of 6.5% can be achieved by minimizing the effects of both circumsolar radiation and slope error.

Baryonic popcorn

NASA Astrophysics Data System (ADS)

Kaplunovsky, Vadim; Melnikov, Dmitry; Sonnenschein, Jacob

2012-11-01

In the large N c limit cold dense nuclear matter must be in a lattice phase. This applies also to holographic models of hadron physics. In a class of such models, like the generalized Sakai-Sugimoto model, baryons take the form of instantons of the effective flavor gauge theory that resides on probe flavor branes. In this paper we study the phase structure of baryonic crystals by analyzing discrete periodic configurations of such instantons. We find that instanton configurations exhibit a series of "popcorn" transitions upon increasing the density. Through these transitions normal (3D) lattices expand into the transverse dimension, eventually becoming a higher dimensional (4D) multi-layer lattice at large densities. We consider 3D lattices of zero size instantons as well as 1D periodic chains of finite size instantons, which serve as toy models of the full holographic systems. In particular, for the finite-size case we determine solutions of the corresponding ADHM equations for both a straight chain and for a 2D zigzag configuration where instantons pop up into the holographic dimension. At low density the system takes the form of an "abelian anti- ferromagnetic" straight periodic chain. Above a critical density there is a second order phase transition into a zigzag structure. An even higher density yields a rich phase space characterized by the formation of multi-layer zigzag structures. The finite size of the lattices in the transverse dimension is a signal of an emerging Fermi sea of quarks. We thus propose that the popcorn transitions indicate the onset of the "quarkyonic" phase of the cold dense nuclear matter.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antonini, Fabio; Chatterjee, Sourav; Rodriguez, Carl L.

Hierarchical triple-star systems are expected to form frequently via close binary–binary encounters in the dense cores of globular clusters (GCs). In a sufficiently inclined triple, gravitational interactions between the inner and outer binary can cause large-amplitude oscillations in the eccentricity of the inner orbit (“Lidov–Kozai (LK) cycles”), which can lead to a collision and merger of the two inner components. In this paper we use Monte Carlo models of dense star clusters to identify all triple systems formed dynamically and we compute their evolution using a highly accurate three-body integrator which incorporates relativistic and tidal effects. We find that amore » large fraction of these triples evolve through a non-secular dynamical phase which can drive the inner binary to higher eccentricities than predicted by the standard secular perturbation theory (even including octupole-order terms). We place constraints on the importance of LK-induced mergers for producing: (i) gravitational wave sources detectable by Advanced LIGO (aLIGO), for triples with an inner pair of stellar black holes (BHs); and (ii) blue straggler stars, for triples with main-sequence-star components. We find a realistic aLIGO detection rate of BH mergers due to the LK mechanism of ∼1 yr{sup −1}, with about 20% of these having a finite eccentricity when they first chirp into the aLIGO frequency band. While rare, these events are likely to dominate among eccentric compact object inspirals that are potentially detectable by aLIGO. For blue stragglers, we find that the LK mechanism can contribute up to ∼10% of their total numbers in GCs.« less

On the Contribution of Large-Scale Structure to Strong Gravitational Lensing

NASA Astrophysics Data System (ADS)

Faure, C.; Kneib, J.-P.; Hilbert, S.; Massey, R.; Covone, G.; Finoguenov, A.; Leauthaud, A.; Taylor, J. E.; Pires, S.; Scoville, N.; Koekemoer, Anton M.

2009-04-01

We study the correlation between the locations of galaxy-galaxy strong-lensing candidates and tracers of large-scale structure from both weak lensing (WL) or X-ray emission. The Cosmological Evolution Survey (COSMOS) is a unique data set, combining deep, high resolution and contiguous imaging in which strong lenses have been discovered, plus unparalleled multiwavelength coverage. To help interpret the COSMOS data, we have also produced mock COSMOS strong- and WL observations, based on ray-tracing through the Millennium Simulation. In agreement with the simulations, we find that strongly lensed images with the largest angular separations are found in the densest regions of the COSMOS field. This is explained by a prevalence among the lens population in dense environments of elliptical galaxies with high total-to-stellar mass ratios, which can deflect light through larger angles. However, we also find that the overall fraction of elliptical galaxies with strong gravitational lensing is independent of the local mass density; this observation is not true of the simulations, which predict an increasing fraction of strong lenses in dense environments. The discrepancy may be a real effect, but could also be explained by various limitations of our analysis. For example, our visual search of strong lens systems could be incomplete and suffer from selection bias; the luminosity function of elliptical galaxies may differ between our real and simulated data; or the simplifying assumptions and approximations used in our lensing simulations may be inadequate. Work is therefore ongoing. Automated searches for strong lens systems will be particularly important in better constraining the selection function.

Exobiology of icy satellites

NASA Astrophysics Data System (ADS)

Simakov, M. B.

At the beginning of 2004 the total number of discovered planets near other stars was 119 All of them are massive giants and met practically in all orbits In a habitable zone from 0 8 up to 1 1 AU at less 11 planets has been found starting with HD 134987 and up to HD 4203 It would be naive to suppose existence of life in unique known to us amino-nucleic acid form on the gas-liquid giant planets Nevertheless conditions for onset and evolutions of life can be realized on hypothetical satellites extrasolar planets All giant planets of the Solar system have a big number of satellites 61 of Jupiter 52 of Saturn known in 2003 A small part of them consist very large bodies quite comparable to planets of terrestrial type but including very significant share of water ice Some from them have an atmosphere E g the mass of a column of the Titan s atmosphere exceeds 15 times the mass of the Earth atmosphere column Formation or capture of satellites is a natural phenomenon and satellite systems definitely should exist at extrasolar planets A hypothetical satellite of the planet HD 28185 with a dense enough atmosphere and hydrosphere could have biosphere of terrestrial type within the limits of our notion about an origin of terrestrial biosphere As an example we can see on Titan the largest satellite of Saturn which has a dense nitrogen atmosphere and a large quantity of liquid water under ice cover and so has a great exobiological significance The most recent models of the Titan s interior lead to the conclusion that a substantial liquid layer

Biomechanical behavior of bone scaffolds made of additive manufactured tricalciumphosphate and titanium alloy under different loading conditions.

PubMed

Wieding, Jan; Fritsche, Andreas; Heinl, Peter; Körner, Carolin; Cornelsen, Matthias; Seitz, Hermann; Mittelmeier, Wolfram; Bader, Rainer

2013-12-16

The repair of large segmental bone defects caused by fracture, tumor or infection remains challenging in orthopedic surgery. The capability of two different bone scaffold materials, sintered tricalciumphosphate and a titanium alloy (Ti6Al4V), were determined by mechanical and biomechanical testing. All scaffolds were fabricated by means of additive manufacturing techniques with identical design and controlled pore geometry. Small-sized sintered TCP scaffolds (10 mm diameter, 21 mm length) were fabricated as dense and open-porous samples and tested in an axial loading procedure. Material properties for titanium alloy were determined by using both tensile (dense) and compressive test samples (open-porous). Furthermore, large-sized open-porous TCP and titanium alloy scaffolds (30 mm in height and diameter, 700 µm pore size) were tested in a biomechanical setup simulating a large segmental bone defect using a composite femur stabilized with an osteosynthesis plate. Static physiologic loads (1.9 kN) were applied within these tests. Ultimate compressive strength of the TCP samples was 11.2 ± 0.7 MPa and 2.2 ± 0.3 MPa, respectively, for the dense and the open-porous samples. Tensile strength and ultimate compressive strength was 909.8 ± 4.9 MPa and 183.3 ± 3.7 MPa, respectively, for the dense and the open-porous titanium alloy samples. Furthermore, the biomechanical results showed good mechanical stability for the titanium alloy scaffolds. TCP scaffolds failed at 30% of the maximum load. Based on recent data, the 3D printed TCP scaffolds tested cannot currently be recommended for high load-bearing situations. Scaffolds made of titanium could be optimized by adapting the biomechanical requirements.

Single-shot mega-electronvolt ultrafast electron diffraction for structure dynamic studies of warm dense matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mo, M. Z., E-mail: mmo09@slac.stanford.edu; Shen, X.; Chen, Z.

We have developed a single-shot mega-electronvolt ultrafast-electron-diffraction system to measure the structural dynamics of warm dense matter. The electron probe in this system is featured by a kinetic energy of 3.2 MeV and a total charge of 20 fC, with the FWHM pulse duration and spot size at sample of 350 fs and 120 μm respectively. We demonstrate its unique capability by visualizing the atomic structural changes of warm dense gold formed from a laser-excited 35-nm freestanding single-crystal gold foil. The temporal evolution of the Bragg peak intensity and of the liquid signal during solid-liquid phase transition are quantitatively determined.more » This experimental capability opens up an exciting opportunity to unravel the atomic dynamics of structural phase transitions in warm dense matter regime.« less

Single-shot mega-electronvolt ultrafast electron diffraction for structure dynamic studies of warm dense matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mo, M. Z.; Shen, X.; Chen, Z.

We have developed a single-shot mega-electronvolt ultrafast-electron-diffraction system to measure the structural dynamics of warm dense matter. The electron probe in this system is featured by a kinetic energy of 3.2 MeV and a total charge of 20 fC, with the FWHM pulse duration and spot size at sample of 350 fs and 120 µm respectively. We demonstrate its unique capability by visualizing the atomic structural changes of warm dense gold formed from a laser-excited 35-nm freestanding single-crystal gold foil. The temporal evolution of the Bragg peak intensity and of the liquid signal during solid-liquid phase transition are quantitatively determined.more » This experimental capability opens up an exciting opportunity to unravel the atomic dynamics of structural phase transitions in warm dense matter regime« less

Universal scaling laws of diffusion in two-dimensional granular liquids.

PubMed

Wang, Chen-Hung; Yu, Szu-Hsuan; Chen, Peilong

2015-06-01

We find, in a two-dimensional air table granular system, that the reduced diffusion constant D* and excess entropy S(2) follow two distinct scaling laws: D*∼e(S(2)*) for dense liquids and D∼e(3S(2)*) for dilute ones. The scaling for dense liquids is very similar to that for three-dimensional liquids proposed previously [M. Dzugutov, Nature (London) 381, 137 (1996); A. Samanta et al., Phys. Rev. Lett. 92, 145901 (2004)]. In the dilute regime, a power law [Y. Rosenfeld, J. Phys.: Condens. Matter 11, 5415 (1999)] also fits our data reasonably well. In our system, particles experience low air drag dissipation and interact with each others through embedded magnets. These near-conservative many-body interactions are responsible for the measured Gaussian velocity distribution functions and the scaling laws. The dominance of cage relaxations in dense liquids leads to the different scaling laws for dense and dilute regimes.

Single-shot mega-electronvolt ultrafast electron diffraction for structure dynamic studies of warm dense matter

DOE PAGES

Mo, M. Z.; Shen, X.; Chen, Z.; ...

2016-08-04

We have developed a single-shot mega-electronvolt ultrafast-electron-diffraction system to measure the structural dynamics of warm dense matter. The electron probe in this system is featured by a kinetic energy of 3.2 MeV and a total charge of 20 fC, with the FWHM pulse duration and spot size at sample of 350 fs and 120 µm respectively. We demonstrate its unique capability by visualizing the atomic structural changes of warm dense gold formed from a laser-excited 35-nm freestanding single-crystal gold foil. The temporal evolution of the Bragg peak intensity and of the liquid signal during solid-liquid phase transition are quantitatively determined.more » This experimental capability opens up an exciting opportunity to unravel the atomic dynamics of structural phase transitions in warm dense matter regime« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitanidis, Peter

As large-scale, commercial storage projects become operational, the problem of utilizing information from diverse sources becomes more critically important. In this project, we developed, tested, and applied an advanced joint data inversion system for CO 2 storage modeling with large data sets for use in site characterization and real-time monitoring. Emphasis was on the development of advanced and efficient computational algorithms for joint inversion of hydro-geophysical data, coupled with state-of-the-art forward process simulations. The developed system consists of (1) inversion tools using characterization data, such as 3D seismic survey (amplitude images), borehole log and core data, as well as hydraulic,more » tracer and thermal tests before CO 2 injection, (2) joint inversion tools for updating the geologic model with the distribution of rock properties, thus reducing uncertainty, using hydro-geophysical monitoring data, and (3) highly efficient algorithms for directly solving the dense or sparse linear algebra systems derived from the joint inversion. The system combines methods from stochastic analysis, fast linear algebra, and high performance computing. The developed joint inversion tools have been tested through synthetic CO 2 storage examples.« less

Matrix Algebra for GPU and Multicore Architectures (MAGMA) for Large Petascale Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dongarra, Jack J.; Tomov, Stanimire

2014-03-24

The goal of the MAGMA project is to create a new generation of linear algebra libraries that achieve the fastest possible time to an accurate solution on hybrid Multicore+GPU-based systems, using all the processing power that future high-end systems can make available within given energy constraints. Our efforts at the University of Tennessee achieved the goals set in all of the five areas identified in the proposal: 1. Communication optimal algorithms; 2. Autotuning for GPU and hybrid processors; 3. Scheduling and memory management techniques for heterogeneity and scale; 4. Fault tolerance and robustness for large scale systems; 5. Building energymore » efficiency into software foundations. The University of Tennessee’s main contributions, as proposed, were the research and software development of new algorithms for hybrid multi/many-core CPUs and GPUs, as related to two-sided factorizations and complete eigenproblem solvers, hybrid BLAS, and energy efficiency for dense, as well as sparse, operations. Furthermore, as proposed, we investigated and experimented with various techniques targeting the five main areas outlined.« less

The support system of the firefighter's activity by detecting objects in smoke space

NASA Astrophysics Data System (ADS)

Sakai, Masaki; Aoki, Yoshimitsu; Takagi, Mikio

2005-12-01

In recent years, crisis management's response to terrorist attacks and natural disasters, as well as accelerating rescue operations has become an important issue. We aim to make a support system for firefighters using the application of various engineering techniques such as information technology and radar technology. In rescue operations, one of the biggest problems is that the view of firefighters is obstructed by dense smoke. One of the current measures against this condition is the use of search sticks, like a blind man walking in town. The most important task for firefighters is to understand inside situation of a space with dense smoke. Therefore, our system supports firefighters' activity by visualizing the space with dense smoke. First, we scan target space with dense smoke by using millimeter-wave radar combined with a gyro sensor. Then multiple directional scan data can be obtained, and we construct a 3D map from high-reflection point dataset using 3D image processing technologies (3D grouping and labeling processing). In this paper, we introduce our system and report the results of the experiment in the real smoke space situation and practical achievements.

Detection of Steel Fatigue Cracks with Strain Sensing Sheets Based on Large Area Electronics

PubMed Central

Yao, Yao; Glisic, Branko

2015-01-01

Reliable early-stage damage detection requires continuous monitoring over large areas of structure, and with sensors of high spatial resolution. Technologies based on Large Area Electronics (LAE) can enable direct sensing and can be scaled to the level required for Structural Health Monitoring (SHM) of civil structures and infrastructure. Sensing sheets based on LAE contain dense arrangements of thin-film strain sensors, associated electronics and various control circuits deposited and integrated on a flexible polyimide substrate that can cover large areas of structures. This paper presents the development stage of a prototype strain sensing sheet based on LAE for crack detection and localization. Two types of sensing-sheet arrangements with size 6 × 6 inch (152 × 152 mm) were designed and manufactured, one with a very dense arrangement of sensors and the other with a less dense arrangement of sensors. The sensing sheets were bonded to steel plates, which had a notch on the boundary, so the fatigue cracks could be generated under cyclic loading. The sensors within the sensing sheet that were close to the notch tip successfully detected the initialization of fatigue crack and localized the damage on the plate. The sensors that were away from the crack successfully detected the propagation of fatigue cracks based on the time history of the measured strain. The results of the tests have validated the general principles of the proposed sensing sheets for crack detection and identified advantages and challenges of the two tested designs. PMID:25853407

Fast Measurement and Reconstruction of Large Workpieces with Freeform Surfaces by Combining Local Scanning and Global Position Data

PubMed Central

Chen, Zhe; Zhang, Fumin; Qu, Xinghua; Liang, Baoqiu

2015-01-01

In this paper, we propose a new approach for the measurement and reconstruction of large workpieces with freeform surfaces. The system consists of a handheld laser scanning sensor and a position sensor. The laser scanning sensor is used to acquire the surface and geometry information, and the position sensor is utilized to unify the scanning sensors into a global coordinate system. The measurement process includes data collection, multi-sensor data fusion and surface reconstruction. With the multi-sensor data fusion, errors accumulated during the image alignment and registration process are minimized, and the measuring precision is significantly improved. After the dense accurate acquisition of the three-dimensional (3-D) coordinates, the surface is reconstructed using a commercial software piece, based on the Non-Uniform Rational B-Splines (NURBS) surface. The system has been evaluated, both qualitatively and quantitatively, using reference measurements provided by a commercial laser scanning sensor. The method has been applied for the reconstruction of a large gear rim and the accuracy is up to 0.0963 mm. The results prove that this new combined method is promising for measuring and reconstructing the large-scale objects with complex surface geometry. Compared with reported methods of large-scale shape measurement, it owns high freedom in motion, high precision and high measurement speed in a wide measurement range. PMID:26091396

Structural Characteristics of Nocturnal Mesoscale Convective Systems in the U.S. Great Plains as Observed During the PECAN Field Campaign

NASA Astrophysics Data System (ADS)

Bodine, D. J.; Dougherty, E.; Rasmussen, K. L.; Torres, A. D.

2015-12-01

During the summer in the U.S. Great Plains, some of the heaviest precipitation falls from large thunderstorm complexes known as Mesoscale Convective Systems (MCSs). These frequently occurring MCSs are often nocturnal in nature, so the dynamics associated with these systems are more elusive than those in the daytime. The Plains Elevated Convection at Night (PECAN) field campaign was launched over a 7-week period as an endeavor to better understand nocturnal MCSs occurring in the Great Plains. PECAN featured a dense array of ground-based and airborne instruments to observe nocturnal MCS, including dual-polarization radars at multiple frequencies, mobile mesonets, and sounding units. Our role in PECAN involved deploying Ott Parsivel disdrometers to gain information on drop size distributions (DSDs) and fall speeds. Analysis of disdrometer data in conjunction with radar data presented using Contour Frequency by Altitude Diagrams (CFADs) and high-resolution radiosonde data allows for a structural comparison of PECAN MCS cases to previously identified MCS archetypes. Novel insights into the structural evolution of nocturnal MCSs in relation to their synoptic, mesoscale, and thermodynamic environments are presented, using data collected from dense and numerous observation platforms. Understanding the environmental conditions that result in different nocturnal MCS configurations is useful for gaining insight into precipitation distributions and potential severe weather and flooding hazards in the Great Plains.

The Neutral Islands during the Late Epoch of Reionization

NASA Astrophysics Data System (ADS)

Xu, Yidong; Yue, Bin; Chen, Xuelei

2018-05-01

The large-scale structure of the ionization field during the epoch of reionization (EoR) can be modeled by the excursion set theory. While the growth of ionized regions during the early stage are described by the ``bubble model'', the shrinking process of neutral regions after the percolation of the ionized region calls for an ``island model''. An excursion set based analytical model and a semi-numerical code (islandFAST) have been developed. The ionizing background and the bubbles inside the islands are also included in the treatment. With two kinds of absorbers of ionizing photons, i.e. the large-scale under-dense neutral islands and the small-scale over-dense clumps, the ionizing background are self-consistently evolved in the model.

The Dynamical Evolution of Stellar-Mass Black Holes in Dense Star Clusters

NASA Astrophysics Data System (ADS)

Morscher, Maggie

Globular clusters are gravitationally bound systems containing up to millions of stars, and are found ubiquitously in massive galaxies, including the Milky Way. With densities as high as a million stars per cubic parsec, they are one of the few places in the Universe where stars interact with one another. They therefore provide us with a unique laboratory for studying how gravitational interactions can facilitate the formation of exotic systems, such as X-ray binaries containing black holes, and merging double black hole binaries, which are produced much less efficiently in isolation. While telescopes can provide us with a snapshot of what these dense clusters look like at present, we must rely on detailed numerical simulations to learn about their evolution. These simulations are quite challenging, however, since dense star clusters are described by a complicated set of physical processes occurring on many different length and time scales, including stellar and binary evolution, weak gravitational scattering encounters, strong resonant binary interactions, and tidal stripping by the host galaxy. Until very recently, it was not possible to model the evolution of systems with millions of stars, the actual number contained in the largest clusters, including all the relevant physics required describe these systems accurately. The Northwestern Group's Henon Monte Carlo code, CMC, which has been in development for over a decade, is a powerful tool that can be used to construct detailed evolutionary models of large star clusters. With its recent parallelization, CMC is now capable of addressing a particularly interesting unsolved problem in astrophysics: the dynamical evolution of stellar black holes in dense star clusters. Our current understanding of the stellar initial mass function and massive star evolution suggests that young globular clusters may have formed hundreds to thousands of stellar-mass black holes, the remnants of stars with initial masses from 20 - 100 Solar masses. Birth kicks from supernova explosions may eject some black holes from their birth clusters, but most should be retained initially. Using our Monte Carlo code, we have investigated the long-term dynamical evolution of globular clusters containing large numbers of stellar black holes. Our study is the first to explore in detail the dynamics of BHs in clusters through a large number of realistic simulations covering a wide range of initial conditions (cluster masses from 105 -- 106 Solar masses, as well as variation in other key parameters, such as the virial radius, central concentration, and metallicity), that also includes all the required physics. In almost all of our models we find that significant numbers of black holes (up to about a 1000) are retained all the way to the present. This is in contrast to previous theoretical expectations that most black holes should be ejected dynamically within a few Gyr. The main reason for this difference is that core collapse driven by black holes (through the Spitzer "mass segregation instability'') is easily reverted through three-body processes, and involves only a small number of the most massive black holes, while lower-mass black holes remain well-mixed with ordinary stars far from the central cusp. Thus the rapid segregation of stellar black holes does not lead to a long-term physical separation of most black holes into a dynamically decoupled inner core, as often assumed previously; this is one of the most important results of this dissertation. Combined with the recent detections of several black hole X-ray binary candidates in Galactic globular clusters, our results suggest that stellar black holes could still be present in large numbers in many globular clusters today, and that they may play a significant role in shaping the long-term dynamical evolution and the present-day dynamical structure of many clusters.

Traveling salesman problem, conformal invariance, and dense polymers.

PubMed

Jacobsen, J L; Read, N; Saleur, H

2004-07-16

We propose that the statistics of the optimal tour in the planar random Euclidean traveling salesman problem is conformally invariant on large scales. This is exhibited in the power-law behavior of the probabilities for the tour to zigzag repeatedly between two regions, and in subleading corrections to the length of the tour. The universality class should be the same as for dense polymers and minimal spanning trees. The conjectures for the length of the tour on a cylinder are tested numerically.

Free-energy landscape for cage breaking of three hard disks.

PubMed

Hunter, Gary L; Weeks, Eric R

2012-03-01

We investigate cage breaking in dense hard-disk systems using a model of three Brownian disks confined within a circular corral. This system has a six-dimensional configuration space, but can be equivalently thought to explore a symmetric one-dimensional free-energy landscape containing two energy minima separated by an energy barrier. The exact free-energy landscape can be calculated as a function of system size by a direct enumeration of states. Results of simulations show the average time between cage breaking events follows an Arrhenius scaling when the energy barrier is large. We also discuss some of the consequences of using a one-dimensional representation to understand dynamics through a multidimensional space, such as diffusion acquiring spatial dependence and discontinuities in spatial derivatives of free energy.

Colony Rheology: Active Arthropods Generate Flows

NASA Astrophysics Data System (ADS)

Daniels, Karen; Mann, Michael; Charbonneau, Patrick

2015-03-01

Hydrodynamic-like flows are observed in biological systems as varied as bacteria, insects, birds, fish, and mammals. Both the phenomenology (e.g. front instabilities, milling motions) and the interaction types (hydrodynamic, direct contact, psychological, excluded-volume) strongly vary between systems, but a question common to all of them is to understand the role of particle-scale fluctuations in controlling large-scale rheological behaviors. We will address these questions through experiments on a new system, Tyrolichus casei (cheese mites), which live in dense, self-mixing colonies composed of a mixture of living mites and inert flour/detritus. In experiments performed in a Hele-Shaw geometry, we observe that the rheology of a colony is strongly dependent on the relative concentration of active and inactive particles. In addition to spreading flows, we also observe that the system can generate convective circulation and auto-compaction.

Controllability of structural brain networks

NASA Astrophysics Data System (ADS)

Gu, Shi; Pasqualetti, Fabio; Cieslak, Matthew; Telesford, Qawi K.; Yu, Alfred B.; Kahn, Ari E.; Medaglia, John D.; Vettel, Jean M.; Miller, Michael B.; Grafton, Scott T.; Bassett, Danielle S.

2015-10-01

Cognitive function is driven by dynamic interactions between large-scale neural circuits or networks, enabling behaviour. However, fundamental principles constraining these dynamic network processes have remained elusive. Here we use tools from control and network theories to offer a mechanistic explanation for how the brain moves between cognitive states drawn from the network organization of white matter microstructure. Our results suggest that densely connected areas, particularly in the default mode system, facilitate the movement of the brain to many easily reachable states. Weakly connected areas, particularly in cognitive control systems, facilitate the movement of the brain to difficult-to-reach states. Areas located on the boundary between network communities, particularly in attentional control systems, facilitate the integration or segregation of diverse cognitive systems. Our results suggest that structural network differences between cognitive circuits dictate their distinct roles in controlling trajectories of brain network function.

Numerical modeling of the early interaction of a planar shock with a dense particle field

NASA Astrophysics Data System (ADS)

Regele, Jonathan; Blanquart, Guillaume

2011-11-01

Dense compressible multiphase flows are of interest for multiphase turbomachinary and energetic material detonations. Still, there is little understanding of the detailed interaction mechanisms between shock waves and dense (particle volume fraction αd > 0 . 001) particle fields. A recent experimental study [Wagner et al, AIAA Aero. Sci., Orlando, 2011-188] has focused on the impingement of a planar shock wave on a dense particle curtain. In the present work, numerical solutions of the Euler equations in one and two dimensions are performed for a planar shock wave impinging on a fixed particle curtain and are compared to the experimental data for early times. Comparison of the one- and two-dimensional results demonstrate that the one-dimensional description captures the large scale flow behavior, but is inadequate to capture all the details observed in the experiments. The two-dimensional solutions are shown to reproduce the experimentally observed flow structures and provide insight into how these details originate.

Ballistic near-field heat transport in dense many-body systems

NASA Astrophysics Data System (ADS)

Latella, Ivan; Biehs, Svend-Age; Messina, Riccardo; Rodriguez, Alejandro W.; Ben-Abdallah, Philippe

2018-01-01

Radiative heat transport mediated by near-field interactions is known to be superdiffusive in dilute, many-body systems. Here we use a generalized Landauer theory of radiative heat transfer in many-body planar systems to demonstrate a nonmonotonic transition from superdiffusive to ballistic transport in dense systems. We show that such a transition is associated to a change of the polarization of dominant modes. Our findings are complemented by a quantitative study of the relaxation dynamics of the system in the different regimes of heat transport. This result could have important consequences on thermal management at nanoscale of many-body systems.

The VIMOS Public Extragalactic Redshift Survey (VIPERS). The distinct build-up of dense and normal massive passive galaxies

NASA Astrophysics Data System (ADS)

Gargiulo, A.; Bolzonella, M.; Scodeggio, M.; Krywult, J.; De Lucia, G.; Guzzo, L.; Garilli, B.; Granett, B. R.; de la Torre, S.; Abbas, U.; Adami, C.; Arnouts, S.; Bottini, D.; Cappi, A.; Cucciati, O.; Davidzon, I.; Franzetti, P.; Fritz, A.; Haines, C.; Hawken, A. J.; Iovino, A.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; Moutard, T.; Polletta, M.; Pollo, A.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Zamorani, G.; Bel, J.; Branchini, E.; Coupon, J.; Ilbert, O.; Moscardini, L.; Peacock, J. A.

2017-10-01

We have used the final data from the VIPERS redshift survey to extract an unparalleled sample of more than 2000 massive ℳ≥1011 M⊙ passive galaxies (MPGs) at redshift 0.5≤z≤1.0, based on their NUVrK colours. This has enabled us to investigate how the population of these objects was built up over cosmic time. We find that the evolution of the number density depends on the galaxy mean surface stellar mass density, Σ. In particular, dense (Σ≥2000 M⊙ pc-2) MPGs show a constant comoving number density over this redshift range, whilst this increases by a factor of approximately four for the least dense objects, defined as having Σ < 1000 M⊙ pc-2. We estimated stellar ages for the MPG population both fitting the spectral energy distribution (SED) and through the D4000n index, obtaining results in good agreement. Our findings are consistent with passive ageing of the stellar content of dense MPGs. We show that at any redshift the less dense MPGs are younger than dense ones and that their stellar populations evolve at a slower rate than predicted by passive evolution. This points to a scenario in which the overall population of MPGs was built up over the cosmic time by continuous addition of less dense galaxies: on top of an initial population of dense objects that passively evolves, new, larger, and younger MPGs continuously join the population at later epochs. Finally, we demonstrate that the observed increase in the number density of MPGs is totally accounted for by the observed decrease in the number density of correspondingly massive star forming galaxies (I.e. all the non-passive ℳ≥1011 M⊙ objects). Such systems observed at z ≃ 1 in VIPERS, therefore, represent the most plausible progenitors of the subsequent emerging class of larger MPGs. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programs 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. The VIPERS web site is http://www.vipers.inaf.it/

A Simple Analytical Model for Asynchronous Dense WDM/OOK Systems

DTIC Science & Technology

1994-06-01

asynchronous dense WDM systems employing an external OOK modulator. Our model is based upon a close approximation of the optical Fabry - Perot filter in the...receiver as a single-pole RC filter for signals that are bandlimitr i, & -equency band approximately equal to one sixtieth of the Fabry - Perot filter’s...4 A. INPUT SIGNAL ............................................................................................... 4 B. FABRY - PEROT FILTERED OUTPUT

Point Cloud Generation from Aerial Image Data Acquired by a Quadrocopter Type Micro Unmanned Aerial Vehicle and a Digital Still Camera

PubMed Central

Rosnell, Tomi; Honkavaara, Eija

2012-01-01

The objective of this investigation was to develop and investigate methods for point cloud generation by image matching using aerial image data collected by quadrocopter type micro unmanned aerial vehicle (UAV) imaging systems. Automatic generation of high-quality, dense point clouds from digital images by image matching is a recent, cutting-edge step forward in digital photogrammetric technology. The major components of the system for point cloud generation are a UAV imaging system, an image data collection process using high image overlaps, and post-processing with image orientation and point cloud generation. Two post-processing approaches were developed: one of the methods is based on Bae Systems’ SOCET SET classical commercial photogrammetric software and another is built using Microsoft®’s Photosynth™ service available in the Internet. Empirical testing was carried out in two test areas. Photosynth processing showed that it is possible to orient the images and generate point clouds fully automatically without any a priori orientation information or interactive work. The photogrammetric processing line provided dense and accurate point clouds that followed the theoretical principles of photogrammetry, but also some artifacts were detected. The point clouds from the Photosynth processing were sparser and noisier, which is to a large extent due to the fact that the method is not optimized for dense point cloud generation. Careful photogrammetric processing with self-calibration is required to achieve the highest accuracy. Our results demonstrate the high performance potential of the approach and that with rigorous processing it is possible to reach results that are consistent with theory. We also point out several further research topics. Based on theoretical and empirical results, we give recommendations for properties of imaging sensor, data collection and processing of UAV image data to ensure accurate point cloud generation. PMID:22368479

Left ventricular strain and its pattern estimated from cine CMR and validation with DENSE

NASA Astrophysics Data System (ADS)

Gao, Hao; Allan, Andrew; McComb, Christie; Luo, Xiaoyu; Berry, Colin

2014-07-01

Measurement of local strain provides insight into the biomechanical significance of viable myocardium. We attempted to estimate myocardial strain from cine cardiovascular magnetic resonance (CMR) images by using a b-spline deformable image registration method. Three healthy volunteers and 41 patients with either recent or chronic myocardial infarction (MI) were studied at 1.5 Tesla with both cine and DENSE CMR. Regional circumferential and radial left ventricular strains were estimated from cine and DENSE acquisitions. In all healthy volunteers, there was no difference for peak circumferential strain (- 0.18 ± 0.04 versus - 0.18 ± 0.03, p = 0.76) between cine and DENSE CMR, however peak radial strain was overestimated from cine (0.84 ± 0.37 versus 0.49 ± 0.2, p < 0.01). In the patient study, the peak strain patterns predicted by cine were similar to the patterns from DENSE, including the strain evolution related to recovery time and strain patterns related to MI scar extent. Furthermore, cine-derived strain disclosed different strain patterns in MI and non-MI regions, and regions with transmural and non-transmural MI as DENSE. Although there were large variations with radial strain measurements from cine CMR images, useful circumferential strain information can be obtained from routine clinical CMR imaging. Cine strain analysis has potential to improve the diagnostic yield from routine CMR imaging in clinical practice.

Laboratory light scattering measurements on "natural" particles with the PROGRA2 experiment: an overview

NASA Astrophysics Data System (ADS)

Hadamcik, E.; Rrenard, J.; Levasseur-Regourd, A. C.; Worms, J. C.

Polarimetric phase curves were obtained with the PROGRA2 instrument for different particles: glass beads, polyhedral solids, rough particles, dense aggregates and aggregates with porosity higher than 90 %. The main purpose of these measurements is to build a large database, which allows interpreting remote sensing observations of solar system bodies. For some samples numerical or experimental models (i.e. DDA, stochastically built particles, microwave analogue) and laboratory experiments are compared to better disentangle the involved physical properties. This paper gives some main results of the experiment, and their applications to Earth atmosphere, comets and asteroids.

Tripolar vortex formation in dense quantum plasma with ion-temperature-gradients

NASA Astrophysics Data System (ADS)

Qamar, Anisa; Ata-ur-Rahman, Mirza, Arshad M.

2012-05-01

We have derived system of nonlinear equations governing the dynamics of low-frequency electrostatic toroidal ion-temperature-gradient mode for dense quantum magnetoplasma. For some specific profiles of the equilibrium density, temperature, and ion velocity gradients, the nonlinear equations admit a stationary solution in the form of a tripolar vortex. These results are relevant to understand nonlinear structure formation in dense quantum plasmas in the presence of equilibrium ion-temperature and density gradients.

Imputation of unordered markers and the impact on genomic selection accuracy

USDA-ARS?s Scientific Manuscript database

Genomic selection, a breeding method that promises to accelerate rates of genetic gain, requires dense, genome-wide marker data. Genotyping-by-sequencing can generate a large number of de novo markers. However, without a reference genome, these markers are unordered and typically have a large propo...

Laboratory and modeling studies of chemistry in dense molecular clouds

NASA Technical Reports Server (NTRS)

Huntress, W. T., Jr.; Prasad, S. S.; Mitchell, G. F.

1980-01-01

A chemical evolutionary model with a large number of species and a large chemical library is used to examine the principal chemical processes in interstellar clouds. Simple chemical equilibrium arguments show the potential for synthesis of very complex organic species by ion-molecule radiative association reactions.

Characterizing urban hydrodynamic models in densely settled river-corridors: Lessons from Jakarta

NASA Astrophysics Data System (ADS)

Shaad, K.; Ninsalam, Y.; Padawangi, R.; Burlando, P.

2016-12-01

The nature and pace of urbanization in South and South-east Asia has created unique circumstances for the inter-action between social and ecological systems linked to water resources - with the growing density of population; frequent and extensive modification on the flood plain alongside governance challenges creating large segment of the settled regions exposed to water security issues and flooding risks. The densely-settled river corridor in Jakarta, with nearly 590 km of waterfront exposed to frequent flooding, captures the scale and complexity typical of these systems. Developing models that can help improve our insights into these urban areas remain a challenge. Here, we present our attempts to apply high-resolution aerial and ground based mapping methods, alongside shallow groundwater monitoring and household surveys, to characterize hydrodynamic models of varying complexity, for a 7 km stretch on the Ciliwung River in the center of Jakarta. We explore the uncertainty associated with obtaining "hydraulically representative" ground description and influence of representation of structures in flood propagation over the short-term, while linking it to the diffusive forcings from settlement acting on the floodplain-river interaction over the long-term. Connecting, thus, flooding with water availability and contamination, we speculate on the ability to scale these approaches and technologies beyond the limits of the test site.

RADIO TRANSIENTS FROM ACCRETION-INDUCED COLLAPSE OF WHITE DWARFS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moriya, Takashi J., E-mail: takashi.moriya@nao.ac.jp

2016-10-20

We investigate observational properties of accretion-induced collapse (AIC) of white dwarfs (WDs) in radio frequencies. If AIC is triggered by accretion from a companion star, a dense circumstellar medium can be formed around the progenitor system. Then, the ejecta from AIC collide with the dense circumstellar medium, creating a strong shock. The strong shock can produce synchrotron emission that can be observed in radio frequencies. Even if AIC occurs as a result of WD mergers, we argue that AIC may cause fast radio bursts (FRBs) if a certain condition is satisfied. If AIC forms neutron stars (NSs) that are somore » massive that rotation is required to support themselves (i.e., supramassive NSs), the supramassive NSs may immediately lose their rotational energy by the r-mode instability and collapse to black holes. If the collapsing supramassive NSs are strongly magnetized, they may emit FRBs, as previously proposed. The AIC radio transients from single-degenerate systems may be detected in future radio transient surveys like the Very Large Array Sky Survey or the Square Kilometer Array transient survey. Because AIC has been proposed as a source of gravitational waves (GWs), GWs from AIC may be accompanied by radio-bright transients that can be used to confirm the AIC origin of observed GWs.« less

A semantic autonomous video surveillance system for dense camera networks in Smart Cities.

PubMed

Calavia, Lorena; Baladrón, Carlos; Aguiar, Javier M; Carro, Belén; Sánchez-Esguevillas, Antonio

2012-01-01

This paper presents a proposal of an intelligent video surveillance system able to detect and identify abnormal and alarming situations by analyzing object movement. The system is designed to minimize video processing and transmission, thus allowing a large number of cameras to be deployed on the system, and therefore making it suitable for its usage as an integrated safety and security solution in Smart Cities. Alarm detection is performed on the basis of parameters of the moving objects and their trajectories, and is performed using semantic reasoning and ontologies. This means that the system employs a high-level conceptual language easy to understand for human operators, capable of raising enriched alarms with descriptions of what is happening on the image, and to automate reactions to them such as alerting the appropriate emergency services using the Smart City safety network.

A Semantic Autonomous Video Surveillance System for Dense Camera Networks in Smart Cities

PubMed Central

Calavia, Lorena; Baladrón, Carlos; Aguiar, Javier M.; Carro, Belén; Sánchez-Esguevillas, Antonio

2012-01-01

This paper presents a proposal of an intelligent video surveillance system able to detect and identify abnormal and alarming situations by analyzing object movement. The system is designed to minimize video processing and transmission, thus allowing a large number of cameras to be deployed on the system, and therefore making it suitable for its usage as an integrated safety and security solution in Smart Cities. Alarm detection is performed on the basis of parameters of the moving objects and their trajectories, and is performed using semantic reasoning and ontologies. This means that the system employs a high-level conceptual language easy to understand for human operators, capable of raising enriched alarms with descriptions of what is happening on the image, and to automate reactions to them such as alerting the appropriate emergency services using the Smart City safety network. PMID:23112607

Ultrastructure of the surface structures and haptor of Empleurosoma pyriforme (Ancyrocephalinae; Monopisthocotylea: Monogenea) from the gills of the teleost fish Therapon jarbua.

PubMed

Ramasamy, P; Brennan, G P

2000-02-01

Infections with Empleurosoma pyriforme occur between successive secondary gill lamellae on both sides of the primary lamella of Therapon jarbua. The haptoral disc bears two pairs of anchors and a pair of connecting transverse bars. The attachment of the parasite to the host gill causes inflammation, erosion and degeneration of the gill epithelia. The ventral anchors consist of an inner core of irregularly arranged, electron-dense fibrils and a smooth outer core of electron-lucent fibrils, whereas the surface of the dorsal anchors is ridged. Both the dorsal and the ventral anchors may be extended or withdrawn. The connecting transverse bars consist of longitudinally arranged fibrils in an electron-dense matrix, whereas the tendons consist of fibrils, supported in a less electron-dense matrix, which interconnect the anchor erector-protractor muscles and the haptor muscles. Two types of perikarya are present. The less common type contain large multivesicular bodies and small electron-dense granules and are located only in the haptor region. The second and more common perikarya are present throughout the body surface. The cytoplasmic syncytium contains numerous electron-dense granules and electron-lucent vesicles. Beneath the syncytium, unicellular epidermal gland cells contain electron-dense granules. Neurones containing numerous electron-dense vesicles are present in the haptor region. Uniciliate presumed sensory receptors are distributed over the body surface. Groups of ciliated sensory structures are present in the forebody. Ciliated and non-ciliated presumed sensory receptors are present in the sleeve cavity of the anchors, on the haptor and in the vicinity of the oral apertures.

Diagnosis of warm dense conditions in foil targets heated by intense femtosecond laser pulses using Kα imaging spectroscopy

DOE PAGES

Bae, L. J.; Zastrau, U.; Chung, H. -K.; ...

2018-03-01

Warm dense conditions in titanium foils irradiated with intense femtosecond laser pulses are diagnosed using an x-ray imaging spectroscopy technique. The line shapes of radially resolved titanium Kα spectra are measured with a toroidally bent GaAs crystal and an x-ray charge-coupled device. Measured spectra are compared with the K-shell emissions modeled using an atomic kinetics – spectroscopy simulation code. Kα line shapes are strongly affected by warm (5-40 eV) bulk electron temperatures and imply multiple temperature distributions in the targets. Finally, the spatial distribution of temperature is dependent on the target thickness, and a thin target shows an advantage tomore » generate uniform warm dense conditions in a large area.« less

A reanalysis of the HCO(+)/HOC(+) abundance ratio in dense interstellar clouds

NASA Technical Reports Server (NTRS)

Jarrold, M. F.; Bowers, M. T.; Defrees, D. J.; Mclean, A. D.; Herbst, E.

1986-01-01

New theoretical and experimental results have prompted a reinvestigation of the HCO(+)/HOC(+) abundance ratio in dense interstellar clouds. These results pertain principally but not exclusively to the reaction between HOC(+) and H2, which was previously calculated by DeFrees et al. (1984) to possess a large activation energy barrier. New calculations, reported here, indicate that this activation energy barrier is quite small and may well be zero. In addition, experimental results at higher energy and temperature indicate strongly that the reaction proceeds efficiently at interstellar temperatures. If HOC(+) does indeed react efficiently with H2 in interstellar clouds, the calculated HCO(+)/HOC(+) abundance ratio rises to a substantially greater value under standard dense cloud conditions than is deduced via the tentative observation of HOC(+) in Sgr B2.

Diagnosis of warm dense conditions in foil targets heated by intense femtosecond laser pulses using Kα imaging spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bae, L. J.; Zastrau, U.; Chung, H. -K.

Warm dense conditions in titanium foils irradiated with intense femtosecond laser pulses are diagnosed using an x-ray imaging spectroscopy technique. The line shapes of radially resolved titanium Kα spectra are measured with a toroidally bent GaAs crystal and an x-ray charge-coupled device. Measured spectra are compared with the K-shell emissions modeled using an atomic kinetics – spectroscopy simulation code. Kα line shapes are strongly affected by warm (5-40 eV) bulk electron temperatures and imply multiple temperature distributions in the targets. Finally, the spatial distribution of temperature is dependent on the target thickness, and a thin target shows an advantage tomore » generate uniform warm dense conditions in a large area.« less

Distributed cyberinfrastructure tools for automated data processing of structural monitoring data

NASA Astrophysics Data System (ADS)

Zhang, Yilan; Kurata, Masahiro; Lynch, Jerome P.; van der Linden, Gwendolyn; Sederat, Hassan; Prakash, Atul

2012-04-01

The emergence of cost-effective sensing technologies has now enabled the use of dense arrays of sensors to monitor the behavior and condition of large-scale bridges. The continuous operation of dense networks of sensors presents a number of new challenges including how to manage such massive amounts of data that can be created by the system. This paper reports on the progress of the creation of cyberinfrastructure tools which hierarchically control networks of wireless sensors deployed in a long-span bridge. The internet-enabled cyberinfrastructure is centrally managed by a powerful database which controls the flow of data in the entire monitoring system architecture. A client-server model built upon the database provides both data-provider and system end-users with secured access to various levels of information of a bridge. In the system, information on bridge behavior (e.g., acceleration, strain, displacement) and environmental condition (e.g., wind speed, wind direction, temperature, humidity) are uploaded to the database from sensor networks installed in the bridge. Then, data interrogation services interface with the database via client APIs to autonomously process data. The current research effort focuses on an assessment of the scalability and long-term robustness of the proposed cyberinfrastructure framework that has been implemented along with a permanent wireless monitoring system on the New Carquinez (Alfred Zampa Memorial) Suspension Bridge in Vallejo, CA. Many data interrogation tools are under development using sensor data and bridge metadata (e.g., geometric details, material properties, etc.) Sample data interrogation clients including those for the detection of faulty sensors, automated modal parameter extraction.

Combining quantitative and qualitative breast density measures to assess breast cancer risk.

PubMed

Kerlikowske, Karla; Ma, Lin; Scott, Christopher G; Mahmoudzadeh, Amir P; Jensen, Matthew R; Sprague, Brian L; Henderson, Louise M; Pankratz, V Shane; Cummings, Steven R; Miglioretti, Diana L; Vachon, Celine M; Shepherd, John A

2017-08-22

Accurately identifying women with dense breasts (Breast Imaging Reporting and Data System [BI-RADS] heterogeneously or extremely dense) who are at high breast cancer risk will facilitate discussions of supplemental imaging and primary prevention. We examined the independent contribution of dense breast volume and BI-RADS breast density to predict invasive breast cancer and whether dense breast volume combined with Breast Cancer Surveillance Consortium (BCSC) risk model factors (age, race/ethnicity, family history of breast cancer, history of breast biopsy, and BI-RADS breast density) improves identifying women with dense breasts at high breast cancer risk. We conducted a case-control study of 1720 women with invasive cancer and 3686 control subjects. We calculated ORs and 95% CIs for the effect of BI-RADS breast density and Volpara™ automated dense breast volume on invasive cancer risk, adjusting for other BCSC risk model factors plus body mass index (BMI), and we compared C-statistics between models. We calculated BCSC 5-year breast cancer risk, incorporating the adjusted ORs associated with dense breast volume. Compared with women with BI-RADS scattered fibroglandular densities and second-quartile dense breast volume, women with BI-RADS extremely dense breasts and third- or fourth-quartile dense breast volume (75% of women with extremely dense breasts) had high breast cancer risk (OR 2.87, 95% CI 1.84-4.47, and OR 2.56, 95% CI 1.87-3.52, respectively), whereas women with extremely dense breasts and first- or second-quartile dense breast volume were not at significantly increased breast cancer risk (OR 1.53, 95% CI 0.75-3.09, and OR 1.50, 95% CI 0.82-2.73, respectively). Adding continuous dense breast volume to a model with BCSC risk model factors and BMI increased discriminatory accuracy compared with a model with only BCSC risk model factors (C-statistic 0.639, 95% CI 0.623-0.654, vs. C-statistic 0.614, 95% CI 0.598-0.630, respectively; P < 0.001). Women with dense breasts and fourth-quartile dense breast volume had a BCSC 5-year risk of 2.5%, whereas women with dense breasts and first-quartile dense breast volume had a 5-year risk ≤ 1.8%. Risk models with automated dense breast volume combined with BI-RADS breast density may better identify women with dense breasts at high breast cancer risk than risk models with either measure alone.

Direct observation of impact propagation and absorption in dense colloidal monolayers

NASA Astrophysics Data System (ADS)

Buttinoni, Ivo; Cha, Jinwoong; Lin, Wei-Hsun; Job, Stéphane; Daraio, Chiara; Isa, Lucio

2017-11-01

Dense colloidal suspensions can propagate and absorb large mechanical stresses, including impacts and shocks. The wave transport stems from the delicate interplay between the spatial arrangement of the structural units and solvent-mediated effects. For dynamic microscopic systems, elastic deformations of the colloids are usually disregarded due to the damping imposed by the surrounding fluid. Here, we study the propagation of localized mechanical pulses in aqueous monolayers of micron-sized particles of controlled microstructure. We generate extreme localized deformation rates by exciting a target particle via pulsed-laser ablation. In crystalline monolayers, stress propagation fronts take place, where fast-moving particles (V approximately a few meters per second) are aligned along the symmetry axes of the lattice. Conversely, more viscous solvents and disordered structures lead to faster and isotropic energy absorption. Our results demonstrate the accessibility of a regime where elastic collisions also become relevant for suspensions of microscopic particles, behaving as “billiard balls” in a liquid, in analogy with regular packings of macroscopic spheres. We furthermore quantify the scattering of an impact as a function of the local structural disorder.

3D road marking reconstruction from street-level calibrated stereo pairs

NASA Astrophysics Data System (ADS)

Soheilian, Bahman; Paparoditis, Nicolas; Boldo, Didier

This paper presents an automatic approach to road marking reconstruction using stereo pairs acquired by a mobile mapping system in a dense urban area. Two types of road markings were studied: zebra crossings (crosswalks) and dashed lines. These two types of road markings consist of strips having known shape and size. These geometric specifications are used to constrain the recognition of strips. In both cases (i.e. zebra crossings and dashed lines), the reconstruction method consists of three main steps. The first step extracts edge points from the left and right images of a stereo pair and computes 3D linked edges using a matching process. The second step comprises a filtering process that uses the known geometric specifications of road marking objects. The goal is to preserve linked edges that can plausibly belong to road markings and to filter others out. The final step uses the remaining linked edges to fit a theoretical model to the data. The method developed has been used for processing a large number of images. Road markings are successfully and precisely reconstructed in dense urban areas under real traffic conditions.

Experimental Determination of DT Yield in High Current DD Dense Plasma Focii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowe, D. R.; Hagen, E. C.; Meehan, B. T.

2013-06-18

Dense Plasma Focii (DPF), which utilize deuterium gas to produce 2.45 MeV neutrons, may in fact also produce DT fusion neutrons at 14.1 MeV due to the triton production in the DD reaction. If beam-target fusion is the primary producer of fusion neutrons in DPFs, it is possible that ejected tritons from the first pinch will interact with the second pinch, and so forth. The 2 MJ DPF at National Security Technologies’ Losee Road Facility is able to, and has produced, over 1E12 DD neutrons per pulse, allowing an accurate measurement of the DT/DD ratio. The DT/DD ratio was experimentallymore » verified by using the (n,2n) reaction in a large piece of praseodymium metal, which has a threshold reaction of 8 MeV, and is widely used as a DT yield measurement system1. The DT/DD ratio was experimentally determined for over 100 shots, and then compared to independent variables such as tube pressure, number of pinches per shot, total current, pinch current and charge voltage.« less

Performance of Point and Range Queries for In-memory Databases using Radix Trees on GPUs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, Maksudul; Yoginath, Srikanth B; Perumalla, Kalyan S

In in-memory database systems augmented by hardware accelerators, accelerating the index searching operations can greatly increase the runtime performance of database queries. Recently, adaptive radix trees (ART) have been shown to provide very fast index search implementation on the CPU. Here, we focus on an accelerator-based implementation of ART. We present a detailed performance study of our GPU-based adaptive radix tree (GRT) implementation over a variety of key distributions, synthetic benchmarks, and actual keys from music and book data sets. The performance is also compared with other index-searching schemes on the GPU. GRT on modern GPUs achieves some of themore » highest rates of index searches reported in the literature. For point queries, a throughput of up to 106 million and 130 million lookups per second is achieved for sparse and dense keys, respectively. For range queries, GRT yields 600 million and 1000 million lookups per second for sparse and dense keys, respectively, on a large dataset of 64 million 32-bit keys.« less

Direct observation of impact propagation and absorption in dense colloidal monolayers

PubMed Central

Cha, Jinwoong; Lin, Wei-Hsun; Job, Stéphane; Daraio, Chiara

2017-01-01

Dense colloidal suspensions can propagate and absorb large mechanical stresses, including impacts and shocks. The wave transport stems from the delicate interplay between the spatial arrangement of the structural units and solvent-mediated effects. For dynamic microscopic systems, elastic deformations of the colloids are usually disregarded due to the damping imposed by the surrounding fluid. Here, we study the propagation of localized mechanical pulses in aqueous monolayers of micron-sized particles of controlled microstructure. We generate extreme localized deformation rates by exciting a target particle via pulsed-laser ablation. In crystalline monolayers, stress propagation fronts take place, where fast-moving particles (V approximately a few meters per second) are aligned along the symmetry axes of the lattice. Conversely, more viscous solvents and disordered structures lead to faster and isotropic energy absorption. Our results demonstrate the accessibility of a regime where elastic collisions also become relevant for suspensions of microscopic particles, behaving as “billiard balls” in a liquid, in analogy with regular packings of macroscopic spheres. We furthermore quantify the scattering of an impact as a function of the local structural disorder. PMID:29087329

Bioconvection as a Consequence of Bio-Stratification in Bacterial Populations

NASA Astrophysics Data System (ADS)

Shoup, Daniel; Strickland, Benjamin; Hoeger, Kentaro; Ursell, Tristan

The collective motion of bacterial populations in solution can generate convective currents that significantly alter fluid motion and material transport. Known as bioconvection, this process is highly influenced by stimuli such as nutrients and toxins that can attract or repel bacteria via chemotaxis. Despite its prevalence in natural environments, ranging from the ocean floor to fluid in the human gut, this dynamic process and the physical and biological factors that influence it remain largely unexplored. To close this gap, we measure and analyze spontaneous bioconvection arising from the collective movement of dense populations of bacteria, such as Escherichia coli and Bacillus subtilis. By combining microscopy and image analysis, we find that modulations of the fluid volume geometry, erasure of the air-liquid interface, chemical perturbations like nutrients or antibiotics all alter the development of these dense bacterial masses and in turn the bio-convective currents and corresponding transport phenomena they generate. Our work suggests biophysical principles of material and organismal transport that apply to a broad range of systems where organisms can sense gradients and move within their environments.

Optical response of nanostructured metal/dielectric composites and multilayers

NASA Astrophysics Data System (ADS)

Smith, Geoffrey B.; Maaroof, Abbas I.; Allan, Rodney S.; Schelm, Stefan; Anstis, Geoffrey R.; Cortie, Michael B.

2004-08-01

The homogeneous optical response in conducting nanostructured layers, and in insulating layers containing dense arrays of self assembled conducting nanoparticles separated by organic linkers, is examined experimentally through their effective complex indices (n*, k*). Classical effective medium models, modified to account for the 3-phase nanostructure, are shown to explain (n*, k*) in dense particulate systems but not inhomogeneous layers with macroscopic conductance for which a different approach to homogenisation is discussed. (n*, k*) data on thin granular metal films, thin mesoporous gold, and on thin metal layers containing ordered arrays of voids, is linked to properties of the surface plasmon states which span the nanostructured film. Coupling between evanescent waves at either surface counterbalanced by electron scattering losses must be considered. Virtual bound states for resonant photons result, with the associated transit delay leading to a large rise in n* in many nanostructures. Overcoating n-Ag with alumina is shown to alter (n*, k*) through its impact on the SP coupling. In contrast to classical optical homogenisation, effective indices depend on film thickness. Supporting high resolution SEM images are presented.

Regenerable Cu-intercalated MnO2 layered cathode for highly cyclable energy dense batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yadav, Gautam G.; Gallaway, Joshua W.; Turney, Damon E.

2017-03-06

Manganese dioxide cathodes are inexpensive and have high theoretical capacity (based on two electrons) of 617 mAh g-1, making them attractive for low-cost, energy-dense batteries. They are used in non-rechargeable batteries with anodes like zinc. Only ~10% of the theoretical capacity is currently accessible in rechargeable alkaline systems. Attempts to access the full capacity using additives have been unsuccessful. We report a class of Bi-birnessite (a layered manganese oxide polymorph mixed with bismuth oxide (Bi2O3)) cathodes intercalated with Cu2+ that deliver near-full two-electron capacity reversibly for >6,000 cycles. The key to rechargeability lies in exploiting the redox potentials of Cumore » to reversibly intercalate into the Bi-birnessite-layered structure during its dissolution and precipitation process for stabilizing and enhancing its charge transfer characteristics. This process holds promise for other applications like catalysis and intercalation of metal ions into layered structures. A large prismatic rechargeable Zn-birnessite cell delivering ~140 Wh l-1 is shown.« less

Linking Microbiota to Human Diseases: A Systems Biology Perspective.

PubMed

Wu, Hao; Tremaroli, Valentina; Bäckhed, Fredrik

2015-12-01

The human gut microbiota encompasses a densely populated ecosystem that provides essential functions for host development, immune maturation, and metabolism. Alterations to the gut microbiota have been observed in numerous diseases, including human metabolic diseases such as obesity, type 2 diabetes (T2D), and irritable bowel syndrome, and some animal experiments have suggested causality. However, few studies have validated causality in humans and the underlying mechanisms remain largely to be elucidated. We discuss how systems biology approaches combined with new experimental technologies may disentangle some of the mechanistic details in the complex interactions of diet, microbiota, and host metabolism and may provide testable hypotheses for advancing our current understanding of human-microbiota interaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Direct synthesis of carbon nanotubes using Cu-Sn catalyst on Cu substrates and their corrosion behavior in 0.6 M NaCl solution

NASA Astrophysics Data System (ADS)

Jeong, Namjo; Jwa, Eunjin; Kim, Chansoo; Choi, Ji Yeon; Nam, Joo-youn; Park, Soon-chul; Jang, Moon-seok

2017-11-01

We report the high-yield and large-area synthesis of a spaghetti-like carbon nanotubes (CNTs) on macroscopic Cu substrates (foil and foam) using a Cu-Sn alloy catalyst. In addition, we investigate the corrosion properties of the as-synthesized CNT/Cu foil system in 0.6 M NaCl solution. Electrochemical analysis showed that the corrosion resistance of the CNT/Cu foil system improved by a factor of ∼100 compared to the as-received Cu foil. Thus, it is concluded that a dense network of CNT was uniformly coated on the Cu foil and this coating functioned as an efficient barrier to corrosion under simulated seawater conditions.

PAH Formation in O-rich Evolved Stars

NASA Astrophysics Data System (ADS)

Guzman-Ramirez, L.; Lagadec, E.; Jones, D.; Zijlstra, A. A.; Gesicki, K.

2015-08-01

Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary nebulae. This combination of oxygen-rich and carbon-rich material, known as dual-dust or mixed chemistry, is not expected to be seen around these objects. We recently proposed that PAHs could be formed from the photodissociation of CO in dense tori. Using VISIR/VLT, we spatially resolved the emission of the PAH bands and ionised emission from the [S IV] line, confirming the presence of dense central tori in all the observed O-rich objects. Furthermore, we show that for most of the objects, PAHs are located at the outer edge of these dense/compact tori, while the ionised material is mostly present in the inner parts, consistent with our hypothesis for the formation of PAHs in these systems. The presence of a dense torus has been strongly associated with the action of a central binary star and, as such, the rich chemistry seen in these regions may also be related to the formation of exoplanets in post-common-envelope binary systems.

Tools to Perform Local Dense 3D Reconstruction of Shallow Water Seabed ‡

PubMed Central

Avanthey, Loïca; Beaudoin, Laurent; Gademer, Antoine; Roux, Michel

2016-01-01

Tasks such as distinguishing or identifying individual objects of interest require the production of dense local clouds at the scale of these individual objects of interest. Due to the physical and dynamic properties of an underwater environment, the usual dense matching algorithms must be rethought in order to be adaptive. These properties also imply that the scene must be observed at close range. Classic robotized acquisition systems are oversized for local studies in shallow water while the systematic acquisition of data is not guaranteed with divers. We address these two major issues through a multidisciplinary approach. To efficiently acquire on-demand stereoscopic pairs using simple logistics in small areas of shallow water, we devised an agile light-weight dedicated system which is easy to reproduce. To densely match two views in a reliable way, we devised a reconstruction algorithm that automatically accounts for the dynamics, variability and light absorption of the underwater environment. Field experiments in the Mediterranean Sea were used to assess the results. PMID:27196913

Improved Estimation and Interpretation of Correlations in Neural Circuits

PubMed Central

Yatsenko, Dimitri; Josić, Krešimir; Ecker, Alexander S.; Froudarakis, Emmanouil; Cotton, R. James; Tolias, Andreas S.

2015-01-01

Ambitious projects aim to record the activity of ever larger and denser neuronal populations in vivo. Correlations in neural activity measured in such recordings can reveal important aspects of neural circuit organization. However, estimating and interpreting large correlation matrices is statistically challenging. Estimation can be improved by regularization, i.e. by imposing a structure on the estimate. The amount of improvement depends on how closely the assumed structure represents dependencies in the data. Therefore, the selection of the most efficient correlation matrix estimator for a given neural circuit must be determined empirically. Importantly, the identity and structure of the most efficient estimator informs about the types of dominant dependencies governing the system. We sought statistically efficient estimators of neural correlation matrices in recordings from large, dense groups of cortical neurons. Using fast 3D random-access laser scanning microscopy of calcium signals, we recorded the activity of nearly every neuron in volumes 200 μm wide and 100 μm deep (150–350 cells) in mouse visual cortex. We hypothesized that in these densely sampled recordings, the correlation matrix should be best modeled as the combination of a sparse graph of pairwise partial correlations representing local interactions and a low-rank component representing common fluctuations and external inputs. Indeed, in cross-validation tests, the covariance matrix estimator with this structure consistently outperformed other regularized estimators. The sparse component of the estimate defined a graph of interactions. These interactions reflected the physical distances and orientation tuning properties of cells: The density of positive ‘excitatory’ interactions decreased rapidly with geometric distances and with differences in orientation preference whereas negative ‘inhibitory’ interactions were less selective. Because of its superior performance, this ‘sparse+latent’ estimator likely provides a more physiologically relevant representation of the functional connectivity in densely sampled recordings than the sample correlation matrix. PMID:25826696

Near-Real Time Monitoring of TEC Over Japan at NICT (RWC Tokyo OF ISES)

NASA Astrophysics Data System (ADS)

Miyake, W.; Jin, H.

2010-05-01

The world wide use of global navigation satellite systems such as GPS offers unique opportunities for a permanent monitoring of the total electron content (TEC) of the ionosphere. We have developed a system of the rapid derivation of TEC from GEONET (a dense GPS receiver network in Japan). In addition to a previous plot of TEC temporal variation over Japan, we have recently developed a near-real-time two-dimensional TEC map and have used it for the daily operation of Space Weather Forecast Center at NICT (Regional Warning Center Tokyo of International Space Environment Service). The TEC map can be used to continuously monitor the ionospheric disturbances over Japan, including spatial and temporal development of ionospheric storms, large-amplitude traveling ionospheric disturbances, and plasma bubbles intruding over Japan, with high time resolution. The development of the real-time monitoring system of TEC enables us to monitor large ionospheric disturbances, ranging from global- to small-scale disturbances, expected in the next solar maximum. The plot and maps are open to the public and are available on http://wdc.nict.go.jp/IONO/index_E.html.

Dense Chern-Simons matter with fermions at large N

DOE PAGES

Geracie, Michael; Goykhman, Mikhail; Son, Dam T.

2016-04-18

In this paper we investigate properties of Chern-Simons theory coupled to massive fermions in the large N limit. We demonstrate that at low temperatures the system is in a Fermi liquid state whose features can be systematically compared to the standard phenomenological theory of Landau Fermi liquids. This includes matching microscopically derived Landau parameters with thermodynamic predictions of Landau Fermi liquid theory. We also calculate the exact conductivity and viscosity tensors at zero temperature and finite chemical potential. In particular we point out that the Hall conductivity of an interacting system is not entirely accounted for by the Berry fluxmore » through the Fermi sphere. Furthermore, investigation of the thermodynamics in the non-relativistic limit reveals novel phenomena at strong coupling. Furthermore, as the ’t Hooft coupling λ approaches 1, the system exhibits an extended intermediate temperature regime in which the thermodynamics is described by neither the quantum Fermi liquid theory nor the classical ideal gas law. Instead, it can be interpreted as a weakly coupled quantum Bose gas.« less

Galaxy evolution in extreme environments: Molecular gas content star formation and AGN in isolated void galaxies

NASA Astrophysics Data System (ADS)

Das, Mousumi; Iono, Daisuke; Saito, Toshiki; Subramanian, Smitha

Since the early redshift surveys of the large scale structure of our universe, it has become clear that galaxies cluster along walls, sheet and filaments leaving large, empty regions called voids between them. Although voids represent the most under dense parts of our universe, they do contain a sparse but significant population of isolated galaxies that are generally low luminosity, late type disk galaxies. Recent studies show that most void galaxies have ongoing star formation and are in an early stage of evolution. We present radio, optical studies of the molecular gas content and star formation in a sample of void galaxies. Using SDSS data, we find that AGN are rare in these systems and are found only in the Bootes void; their black hole masses and radio properties are similar to bright spirals galaxies. Our studies suggest that close galaxy interactions and gas accretion are the main drivers of galaxy evolution in these systems despite their location in the underdense environment of the voids.

Hybrid multiphoton volumetric functional imaging of large-scale bioengineered neuronal networks

NASA Astrophysics Data System (ADS)

Dana, Hod; Marom, Anat; Paluch, Shir; Dvorkin, Roman; Brosh, Inbar; Shoham, Shy

2014-06-01

Planar neural networks and interfaces serve as versatile in vitro models of central nervous system physiology, but adaptations of related methods to three dimensions (3D) have met with limited success. Here, we demonstrate for the first time volumetric functional imaging in a bioengineered neural tissue growing in a transparent hydrogel with cortical cellular and synaptic densities, by introducing complementary new developments in nonlinear microscopy and neural tissue engineering. Our system uses a novel hybrid multiphoton microscope design combining a 3D scanning-line temporal-focusing subsystem and a conventional laser-scanning multiphoton microscope to provide functional and structural volumetric imaging capabilities: dense microscopic 3D sampling at tens of volumes per second of structures with mm-scale dimensions containing a network of over 1,000 developing cells with complex spontaneous activity patterns. These developments open new opportunities for large-scale neuronal interfacing and for applications of 3D engineered networks ranging from basic neuroscience to the screening of neuroactive substances.

DICCCOL: Dense Individualized and Common Connectivity-Based Cortical Landmarks

PubMed Central

Zhu, Dajiang; Guo, Lei; Jiang, Xi; Zhang, Tuo; Zhang, Degang; Chen, Hanbo; Deng, Fan; Faraco, Carlos; Jin, Changfeng; Wee, Chong-Yaw; Yuan, Yixuan; Lv, Peili; Yin, Yan; Hu, Xiaolei; Duan, Lian; Hu, Xintao; Han, Junwei; Wang, Lihong; Shen, Dinggang; Miller, L Stephen

2013-01-01

Is there a common structural and functional cortical architecture that can be quantitatively encoded and precisely reproduced across individuals and populations? This question is still largely unanswered due to the vast complexity, variability, and nonlinearity of the cerebral cortex. Here, we hypothesize that the common cortical architecture can be effectively represented by group-wise consistent structural fiber connections and take a novel data-driven approach to explore the cortical architecture. We report a dense and consistent map of 358 cortical landmarks, named Dense Individualized and Common Connectivity–based Cortical Landmarks (DICCCOLs). Each DICCCOL is defined by group-wise consistent white-matter fiber connection patterns derived from diffusion tensor imaging (DTI) data. Our results have shown that these 358 landmarks are remarkably reproducible over more than one hundred human brains and possess accurate intrinsically established structural and functional cross-subject correspondences validated by large-scale functional magnetic resonance imaging data. In particular, these 358 cortical landmarks can be accurately and efficiently predicted in a new single brain with DTI data. Thus, this set of 358 DICCCOL landmarks comprehensively encodes the common structural and functional cortical architectures, providing opportunities for many applications in brain science including mapping human brain connectomes, as demonstrated in this work. PMID:22490548

Direct evidence for Lyboldsymbol{alpha } depletion in the protocluster core

NASA Astrophysics Data System (ADS)

Shimakawa, Rhythm; Kodama, Tadayuki; Hayashi, Masao; Tanaka, Ichi; Matsuda, Yuichi; Kashikawa, Nobunari; Shibuya, Takatoshi; Tadaki, Ken-ichi; Koyama, Yusei; Suzuki, Tomoko L.; Yamamoto, Moegi

2017-06-01

We have carried out panoramic Lyα narrow-band imaging with Suprime-Cam on Subaru towards the known protocluster USS1558-003 at z = 2.53. Our previous narrow-band imaging in the near-infrared identified multiple dense groups of Hα emitters (HAEs) within the protocluster. We have now identified the large-scale structures across a ˜50 comoving Mpc scale traced by Lyα emitters (LAEs) in which the protocluster traced by the HAEs is embedded. On a smaller scale, however, there are remarkably few LAEs in the regions of HAE overdensities. Moreover, the stacking analyses of the images show that HAEs in higher-density regions show systematically lower escape fractions of Lyα photons than those of HAEs in lower-density regions. These phenomena may be driven by the extra depletion of Lyα emission lines along our line of sight by more intervening cold circumgalactic/intergalactic medium and/or dust in the dense core. We also caution that all the previous high-z protocluster surveys using LAEs as tracers would have largely missed galaxies in the very dense cores of the protoclusters where we would expect to see any early environmental effects.

Fine-scale distribution of zooplankton is linked to phytoplankton species composition and abundance in a North Norwegian fjord system

NASA Astrophysics Data System (ADS)

Norrbin, F.; Priou, P. D.; Varela, A. P.

2016-02-01

We studied the influence of dense layers of phytoplankton and aggregates on shaping the vertical distribution of zooplankton in a North Norwegian fjord using a Video Plankton Recorder (VPR). This instrument provided fine-scale vertical distribution (cm-m scale) of planktonic organisms as well as aggregates of marine snow in relation to environmental conditions. At the height - later stage of the spring phytoplankton bloom in May, the outer part of the fjord was dominated by Phaeocystis pouchetii, while diatoms (Chaetoceros spp.) were dominating in the innermost basin. Small copepods species like Pseudocalanus spp., Microsetella norvegica, and Oithona spp. prevailed over larger copepod species in the inner part of the fjord whereas the outer part was dominated by large copepods like Calanus finmarchicus. While the zooplankton where spread out over the water column during the early stage of the bloom, in May they were linked to the phytoplankton vertical distribution and in the winter situation they were found in deeper waters. Herbivorous zooplankton species were affected by phytoplankton species composition; C. finmarchicus and Pseudocalanus spp. avoided the dense layer of P. pouchetii while herbivorous zooplankton matched the distribution of the diatom-dominated bloom. Small, omnivorous copepod species like Microsetella sp., Oithona sp. and Pseudocalanus sp. were often associated with dense layers of snow aggregates. This distribution may provide a shelter from predators as well as a food source. Natural or anthropogenic-induced changes in phytoplankton composition and aggregate distribution may thus influence food-web interactions.

Weak synchronization and large-scale collective oscillation in dense bacterial suspensions

NASA Astrophysics Data System (ADS)

Chen, Chong; Liu, Song; Shi, Xia-Qing; Chaté, Hugues; Wu, Yilin

2017-01-01

Collective oscillatory behaviour is ubiquitous in nature, having a vital role in many biological processes from embryogenesis and organ development to pace-making in neuron networks. Elucidating the mechanisms that give rise to synchronization is essential to the understanding of biological self-organization. Collective oscillations in biological multicellular systems often arise from long-range coupling mediated by diffusive chemicals, by electrochemical mechanisms, or by biomechanical interaction between cells and their physical environment. In these examples, the phase of some oscillatory intracellular degree of freedom is synchronized. Here, in contrast, we report the discovery of a weak synchronization mechanism that does not require long-range coupling or inherent oscillation of individual cells. We find that millions of motile cells in dense bacterial suspensions can self-organize into highly robust collective oscillatory motion, while individual cells move in an erratic manner, without obvious periodic motion but with frequent, abrupt and random directional changes. So erratic are individual trajectories that uncovering the collective oscillations of our micrometre-sized cells requires individual velocities to be averaged over tens or hundreds of micrometres. On such large scales, the oscillations appear to be in phase and the mean position of cells typically describes a regular elliptic trajectory. We found that the phase of the oscillations is organized into a centimetre-scale travelling wave. We present a model of noisy self-propelled particles with strictly local interactions that accounts faithfully for our observations, suggesting that self-organized collective oscillatory motion results from spontaneous chiral and rotational symmetry breaking. These findings reveal a previously unseen type of long-range order in active matter systems (those in which energy is spent locally to produce non-random motion). This mechanism of collective oscillation may inspire new strategies to control the self-organization of active matter and swarming robots.

Weak synchronization and large-scale collective oscillation in dense bacterial suspensions.

PubMed

Chen, Chong; Liu, Song; Shi, Xia-Qing; Chaté, Hugues; Wu, Yilin

2017-02-09

Collective oscillatory behaviour is ubiquitous in nature, having a vital role in many biological processes from embryogenesis and organ development to pace-making in neuron networks. Elucidating the mechanisms that give rise to synchronization is essential to the understanding of biological self-organization. Collective oscillations in biological multicellular systems often arise from long-range coupling mediated by diffusive chemicals, by electrochemical mechanisms, or by biomechanical interaction between cells and their physical environment. In these examples, the phase of some oscillatory intracellular degree of freedom is synchronized. Here, in contrast, we report the discovery of a weak synchronization mechanism that does not require long-range coupling or inherent oscillation of individual cells. We find that millions of motile cells in dense bacterial suspensions can self-organize into highly robust collective oscillatory motion, while individual cells move in an erratic manner, without obvious periodic motion but with frequent, abrupt and random directional changes. So erratic are individual trajectories that uncovering the collective oscillations of our micrometre-sized cells requires individual velocities to be averaged over tens or hundreds of micrometres. On such large scales, the oscillations appear to be in phase and the mean position of cells typically describes a regular elliptic trajectory. We found that the phase of the oscillations is organized into a centimetre-scale travelling wave. We present a model of noisy self-propelled particles with strictly local interactions that accounts faithfully for our observations, suggesting that self-organized collective oscillatory motion results from spontaneous chiral and rotational symmetry breaking. These findings reveal a previously unseen type of long-range order in active matter systems (those in which energy is spent locally to produce non-random motion). This mechanism of collective oscillation may inspire new strategies to control the self-organization of active matter and swarming robots.

LSRN: A PARALLEL ITERATIVE SOLVER FOR STRONGLY OVER- OR UNDERDETERMINED SYSTEMS*

PubMed Central

Meng, Xiangrui; Saunders, Michael A.; Mahoney, Michael W.

2014-01-01

We describe a parallel iterative least squares solver named LSRN that is based on random normal projection. LSRN computes the min-length solution to minx∈ℝn ‖Ax − b‖2, where A ∈ ℝm × n with m ≫ n or m ≪ n, and where A may be rank-deficient. Tikhonov regularization may also be included. Since A is involved only in matrix-matrix and matrix-vector multiplications, it can be a dense or sparse matrix or a linear operator, and LSRN automatically speeds up when A is sparse or a fast linear operator. The preconditioning phase consists of a random normal projection, which is embarrassingly parallel, and a singular value decomposition of size ⌈γ min(m, n)⌉ × min(m, n), where γ is moderately larger than 1, e.g., γ = 2. We prove that the preconditioned system is well-conditioned, with a strong concentration result on the extreme singular values, and hence that the number of iterations is fully predictable when we apply LSQR or the Chebyshev semi-iterative method. As we demonstrate, the Chebyshev method is particularly efficient for solving large problems on clusters with high communication cost. Numerical results show that on a shared-memory machine, LSRN is very competitive with LAPACK’s DGELSD and a fast randomized least squares solver called Blendenpik on large dense problems, and it outperforms the least squares solver from SuiteSparseQR on sparse problems without sparsity patterns that can be exploited to reduce fill-in. Further experiments show that LSRN scales well on an Amazon Elastic Compute Cloud cluster. PMID:25419094

Constraining Earth System Models in the Tropics with Multiple Satellite Observations

NASA Astrophysics Data System (ADS)

Shi, M.; Liu, J.; Saatchi, S. S.; Chan, S.; Yu, Y.; Zhao, M.

2016-12-01

Because of the impacts of cloud and atmospheric aerosol on spectral observations and the saturation of spectral observations over dense forests, the current spectral observations (e.g., Moderate Resolution Imaging Spectroradiometer) have large uncertainties in the tropics. Nevertheless, the backscatter observations from the SeaWinds Scatterometer onboard QuikSCAT (QSCAT) are sensitive to the variations of canopy water content and structure of forest canopy, and are not affected by clouds and atmospheric aerosols. In addition, the lack of sensitivity of the Soil Moisture Active Passive (SMAP) Level 1C brightness temperature (TB) to soil moisture under dense forest canopies (e.g., forests in tropics) makes the SMAP TB data a direct indicator of canopy properties. In this study, we use a variety of new satellite observations, including the QSCAT backscatter observations, the Gravity Recovery and Climate Experiment (GRACE) satellite's observed temporal gravity field variations, and the SMAP Level 1C TB, to constrain the carbon (C) cycle simulated by the Community Land Model version 4.5 BGC (CLM4.5) for the 2005 Amazonia drought and 2015 El Nino. Our results show that the leaf C pool size simulated by CLM4.5 decreases dramatically in southwest Amazonia in the 2005 drought, and recovers slowly afterward (after about 3 years). This result is consistent with the long-term C-recovery after the 2005 Amazonia drought observed by QSCAT. The slow C pool recovery is associated with large fire disturbance and the slow water storage recovery simulated by CLM4.5 and observed by GRACE. We will also discuss the impact of the 2015 El Nino on the tropical C dynamics constrained by SMAP Level 1C data. This study represents an innovative way of using satellite microwave observations to constrain C cycle in an Earth system model.

Reducing stand densities in immature and mature stands, Applegate Watershed, Southwest Oregon.

Treesearch

Marty L. Main; Michael P. Amaranthus

1996-01-01

Abstract Throughout the Applegate watershed, dense, overstocked, immature stands of mixed conifers and hardwoods and declining stands of mature conifers present significant and complex silvicultural problems. Stand stagnation is common, as is loss of large-diameter conifers from insects and wildfire. Treatments designed to maintain or encourage development of large-...

DEVELOPMENT OF LOW-DIFFUSION FLUX-SPLITTING METHODS FOR DENSE GAS-SOLID FLOWS

EPA Science Inventory

The development of a class of low-diffusion upwinding methods for computing dense gas-solid flows is presented in this work. An artificial compressibility/low-Mach preconditioning strategy is developed for a hyperbolic two-phase flow equation system consisting of separate solids ...

Design and implemention of a multi-functional x-ray computed tomography system

NASA Astrophysics Data System (ADS)

Li, Lei; Xi, Xiaoqi; Han, Yu; Yan, Bin; Zhang, Xiang; Deng, Lin; Chen, Siyu; Jin, Zhao; Li, Zengguang

2015-10-01

A powerful volume X-ray tomography system has been designed and constructed to provide an universal tool for the three-dimensional nondestructive testing and investigation of industrial components, automotive, electronics, aerospace components, new materials, etc. The combined system is equipped with two commercial X-ray sources, sharing one flat panel detector of 400mm×400mm. The standard focus 450kV high-energy x-ray source is optimized for complex and high density components such as castings, engine blocks and turbine blades. And the microfocus 225kV x-ray source is to meet the demands of micro-resolution characterization applications. Thus the system's penetration capability allows to scan large objects up to 200mm thick dense materials, and the resolution capability can meet the demands of 20μm microstructure inspection. A high precision 6-axis manipulator system is fitted, capable of offset scanning mode in large field of view requirements. All the components are housed in a room with barium sulphate cement. On the other hand, the presented system expands the scope of applications such as dual energy research and testing. In this paper, the design and implemention of the flexible system is described, as well as the preliminary tomographic imaging results of an automobile engine block.

Reorganization of a dense granular assembly: The unjamming response function

NASA Astrophysics Data System (ADS)

Kolb, Évelyne; Cviklinski, Jean; Lanuza, José; Claudin, Philippe; Clément, Éric

2004-03-01

We investigate the mechanical properties of a static dense granular assembly in response to a local forcing. To this end, a small cyclic displacement is applied on a grain in the bulk of a two-dimensional disordered packing under gravity and the displacement fields are monitored. We evidence a dominant long range radial response in the upper half part above the solicitation and after a large number of cycles the response is “quasireversible” with a remanent dissipation field exhibiting long range streams and vortexlike symmetry.

Environmental Catastrophes in the Earth's History Due to Solar Systems Encounters with Giant Molecular Clouds

NASA Technical Reports Server (NTRS)

Pavlov, Alexander A.

2011-01-01

In its motion through the Milky Way galaxy, the solar system encounters an average density (>=330 H atoms/cubic cm) giant molecular cloud (GMC) approximately every 108 years, a dense (approx 2 x 103 H atoms/cubic cm) GMC every approx 109 years and will inevitably encounter them in the future. However, there have been no studies linking such events with severe (snowball) glaciations in Earth history. Here we show that dramatic climate change can be caused by interstellar dust accumulating in Earth's atmosphere during the solar system's immersion into a dense (approx ,2 x 103 H atoms/cubic cm) GMC. The stratospheric dust layer from such interstellar particles could provide enough radiative forcing to trigger the runaway ice-albedo feedback that results in global snowball glaciations. We also demonstrate that more frequent collisions with less dense GMCs could cause moderate ice ages.

Elasticity-induced force reversal between active spinning particles in dense passive media

PubMed Central

Aragones, J. L.; Steimel, J. P.; Alexander-Katz, A.

2016-01-01

The self-organization of active particles is governed by their dynamic effective interactions. Such interactions are controlled by the medium in which such active agents reside. Here we study the interactions between active agents in a dense non-active medium. Our system consists of actuated, spinning, active particles embedded in a dense monolayer of passive, or non-active, particles. We demonstrate that the presence of the passive monolayer alters markedly the properties of the system and results in a reversal of the forces between active spinning particles from repulsive to attractive. The origin of such reversal is due to the coupling between the active stresses and elasticity of the system. This discovery provides a mechanism for the interaction between active agents in complex and structured media, opening up opportunities to tune the interaction range and directionality via the mechanical properties of the medium. PMID:27112961

Visualization of expanding warm dense gold and diamond heated rapidly by laser-generated ion beams

DOE PAGES

Bang, W.; Albright, B. J.; Bradley, P. A.; ...

2015-09-22

With the development of several novel heating sources, scientists can now heat a small sample isochorically above 10,000 K. Although matter at such an extreme state, known as warm dense matter, is commonly found in astrophysics (e.g., in planetary cores) as well as in high energy density physics experiments, its properties are not well understood and are difficult to predict theoretically. This is because the approximations made to describe condensed matter or high-temperature plasmas are invalid in this intermediate regime. A sufficiently large warm dense matter sample that is uniformly heated would be ideal for these studies, but has beenmore » unavailable to date. We have used a beam of quasi-monoenergetic aluminum ions to heat gold and diamond foils uniformly and isochorically. For the first time, we visualized directly the expanding warm dense gold and diamond with an optical streak camera. Furthermore, we present a new technique to determine the initial temperature of these heated samples from the measured expansion speeds of gold and diamond into vacuum. We anticipate the uniformly heated solid density target will allow for direct quantitative measurements of equation-of-state, conductivity, opacity, and stopping power of warm dense matter, benefiting plasma physics, astrophysics, and nuclear physics.« less

Visualization of expanding warm dense gold and diamond heated rapidly by laser-generated ion beams.

PubMed

Bang, W; Albright, B J; Bradley, P A; Gautier, D C; Palaniyappan, S; Vold, E L; Santiago Cordoba, M A; Hamilton, C E; Fernández, J C

2015-09-22

With the development of several novel heating sources, scientists can now heat a small sample isochorically above 10,000 K. Although matter at such an extreme state, known as warm dense matter, is commonly found in astrophysics (e.g., in planetary cores) as well as in high energy density physics experiments, its properties are not well understood and are difficult to predict theoretically. This is because the approximations made to describe condensed matter or high-temperature plasmas are invalid in this intermediate regime. A sufficiently large warm dense matter sample that is uniformly heated would be ideal for these studies, but has been unavailable to date. Here we have used a beam of quasi-monoenergetic aluminum ions to heat gold and diamond foils uniformly and isochorically. For the first time, we visualized directly the expanding warm dense gold and diamond with an optical streak camera. Furthermore, we present a new technique to determine the initial temperature of these heated samples from the measured expansion speeds of gold and diamond into vacuum. We anticipate the uniformly heated solid density target will allow for direct quantitative measurements of equation-of-state, conductivity, opacity, and stopping power of warm dense matter, benefiting plasma physics, astrophysics, and nuclear physics.

Visualization of expanding warm dense gold and diamond heated rapidly by laser-generated ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bang, W.; Albright, B. J.; Bradley, P. A.

With the development of several novel heating sources, scientists can now heat a small sample isochorically above 10,000 K. Although matter at such an extreme state, known as warm dense matter, is commonly found in astrophysics (e.g., in planetary cores) as well as in high energy density physics experiments, its properties are not well understood and are difficult to predict theoretically. This is because the approximations made to describe condensed matter or high-temperature plasmas are invalid in this intermediate regime. A sufficiently large warm dense matter sample that is uniformly heated would be ideal for these studies, but has beenmore » unavailable to date. We have used a beam of quasi-monoenergetic aluminum ions to heat gold and diamond foils uniformly and isochorically. For the first time, we visualized directly the expanding warm dense gold and diamond with an optical streak camera. Furthermore, we present a new technique to determine the initial temperature of these heated samples from the measured expansion speeds of gold and diamond into vacuum. We anticipate the uniformly heated solid density target will allow for direct quantitative measurements of equation-of-state, conductivity, opacity, and stopping power of warm dense matter, benefiting plasma physics, astrophysics, and nuclear physics.« less

Visualization of expanding warm dense gold and diamond heated rapidly by laser-generated ion beams

NASA Astrophysics Data System (ADS)

Bang, W.; Albright, B. J.; Bradley, P. A.; Gautier, D. C.; Palaniyappan, S.; Vold, E. L.; Cordoba, M. A. Santiago; Hamilton, C. E.; Fernández, J. C.

2015-09-01

With the development of several novel heating sources, scientists can now heat a small sample isochorically above 10,000 K. Although matter at such an extreme state, known as warm dense matter, is commonly found in astrophysics (e.g., in planetary cores) as well as in high energy density physics experiments, its properties are not well understood and are difficult to predict theoretically. This is because the approximations made to describe condensed matter or high-temperature plasmas are invalid in this intermediate regime. A sufficiently large warm dense matter sample that is uniformly heated would be ideal for these studies, but has been unavailable to date. Here we have used a beam of quasi-monoenergetic aluminum ions to heat gold and diamond foils uniformly and isochorically. For the first time, we visualized directly the expanding warm dense gold and diamond with an optical streak camera. Furthermore, we present a new technique to determine the initial temperature of these heated samples from the measured expansion speeds of gold and diamond into vacuum. We anticipate the uniformly heated solid density target will allow for direct quantitative measurements of equation-of-state, conductivity, opacity, and stopping power of warm dense matter, benefiting plasma physics, astrophysics, and nuclear physics.

River runoff influences on the Central Mediterranean overturning circulation

NASA Astrophysics Data System (ADS)

Verri, Giorgia; Pinardi, N.; Oddo, P.; Ciliberti, S. A.; Coppini, G.

2018-03-01

The role of riverine freshwater inflow on the Central Mediterranean Overturning Circulation (CMOC) was studied using a high-resolution ocean model with a complete distribution of rivers in the Adriatic and Ionian catchment areas. The impact of river runoff on the Adriatic and Ionian Sea basins was assessed by a twin experiment, with and without runoff, from 1999 to 2012. This study tries to show the connection between the Adriatic as a marginal sea containing the downwelling branch of the anti-estuarine CMOC and the large runoff occurring there. It is found that the multiannual CMOC is a persistent anti-estuarine structure with secondary estuarine cells that strengthen in years of large realistic river runoff. The CMOC is demonstrated to be controlled by wind forcing at least as much as by buoyancy fluxes. It is found that river runoff affects the CMOC strength, enhancing the amplitude of the secondary estuarine cells and reducing the intensity of the dominant anti-estuarine cell. A large river runoff can produce a positive buoyancy flux without switching off the antiestuarine CMOC cell, but a particularly low heat flux and wind work with normal river runoff can reverse it. Overall by comparing experiments with, without and with unrealistically augmented runoff we demonstrate that rivers affect the CMOC strength but they can never represent its dominant forcing mechanism and the potential role of river runoff has to be considered jointly with wind work and heat flux, as they largely contribute to the energy budget of the basin. Looking at the downwelling branch of the CMOC in the Adriatic basin, rivers are demonstrated to locally reduce the volume of Adriatic dense water formed in the Southern Adriatic Sea as a result of increased water stratification. The spreading of the Adriatic dense water into the Ionian abyss is affected as well: dense waters overflowing the Otranto Strait are less dense in a realistic runoff regime, with respect to no runoff experiment, and confined to a narrower band against the Italian shelf with less lateral spreading toward the Ionian Sea center.

Quantum Linear System Algorithm for Dense Matrices.

PubMed

Wossnig, Leonard; Zhao, Zhikuan; Prakash, Anupam

2018-02-02

Solving linear systems of equations is a frequently encountered problem in machine learning and optimization. Given a matrix A and a vector b the task is to find the vector x such that Ax=b. We describe a quantum algorithm that achieves a sparsity-independent runtime scaling of O(κ^{2}sqrt[n]polylog(n)/ε) for an n×n dimensional A with bounded spectral norm, where κ denotes the condition number of A, and ε is the desired precision parameter. This amounts to a polynomial improvement over known quantum linear system algorithms when applied to dense matrices, and poses a new state of the art for solving dense linear systems on a quantum computer. Furthermore, an exponential improvement is achievable if the rank of A is polylogarithmic in the matrix dimension. Our algorithm is built upon a singular value estimation subroutine, which makes use of a memory architecture that allows for efficient preparation of quantum states that correspond to the rows of A and the vector of Euclidean norms of the rows of A.

PHOTOCHEMICAL HEATING OF DENSE MOLECULAR GAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glassgold, A. E.; Najita, J. R.

2015-09-10

Photochemical heating is analyzed with an emphasis on the heating generated by chemical reactions initiated by the products of photodissociation and photoionization. The immediate products are slowed down by collisions with the ambient gas and then heat the gas. In addition to this direct process, heating is also produced by the subsequent chemical reactions initiated by these products. Some of this chemical heating comes from the kinetic energy of the reaction products and the rest from collisional de-excitation of the product atoms and molecules. In considering dense gas dominated by molecular hydrogen, we find that the chemical heating is sometimesmore » as large, if not much larger than, the direct heating. In very dense gas, the total photochemical heating approaches 10 eV per photodissociation (or photoionization), competitive with other ways of heating molecular gas.« less

Optical Pumping of High Power Lasers with an Array of Plasma Pinches.

DTIC Science & Technology

1986-04-01

Two dense plasma focus systems, the hypocycloidal pinch and the Mather type were investigated as the potential excitation light sources for high...was also performed for the first time using the Mather type dense plasma focus (MDPF) sucsessfully. Results thus fare indicate that both HCP and MDPF

Core Emergence in a Massive Infrared Dark Cloud: A Comparison between Mid-IR Extinction and 1.3 mm Emission

NASA Astrophysics Data System (ADS)

Kong, Shuo; Tan, Jonathan C.; Arce, Héctor G.; Caselli, Paola; Fontani, Francesco; Butler, Michael J.

2018-03-01

Stars are born from dense cores in molecular clouds. Observationally, it is crucial to capture the formation of cores in order to understand the necessary conditions and rate of the star formation process. The Atacama Large Millimeter/submillimeter Array (ALMA) is extremely powerful for identifying dense gas structures, including cores, at millimeter wavelengths via their dust continuum emission. Here, we use ALMA to carry out a survey of dense gas and cores in the central region of the massive (∼105 M ⊙) infrared dark cloud (IRDC) G28.37+0.07. The observation consists of a mosaic of 86 pointings of the 12 m array and produces an unprecedented view of the densest structures of this IRDC. In this first Letter about this data set, we focus on a comparison between the 1.3 mm continuum emission and a mid-infrared (MIR) extinction map of the IRDC. This allows estimation of the “dense gas” detection probability function (DPF), i.e., as a function of the local mass surface density, Σ, for various choices of thresholds of millimeter continuum emission to define “dense gas.” We then estimate the dense gas mass fraction, f dg, in the central region of the IRDC and, via extrapolation with the DPF and the known Σ probability distribution function, to the larger-scale surrounding regions, finding values of about 5% to 15% for the fiducial choice of threshold. We argue that this observed dense gas is a good tracer of the protostellar core population and, in this context, estimate a star formation efficiency per free-fall time in the central IRDC region of ɛ ff ∼ 10%, with approximately a factor of two systematic uncertainties.

Collaborative Research: Neutrinos & Nucleosynthesis in Hot Dense Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddy, Sanjay

2013-09-06

It is now firmly established that neutrinos, which are copiously produced in the hot and dense core of the supernova, play a role in the supernova explosion mechanism and in the synthesis of heavy elements through a phenomena known as r-process nucleosynthesis. They are also detectable in terrestrial neutrino experiments, and serve as a probe of the extreme environment and complex dynamics encountered in the supernova. The major goal of the UW research activity relevant to this project was to calculate the neutrino interaction rates in hot and dense matter of relevance to core collapse supernova. These serve as keymore » input physics in large scale computer simulations of the supernova dynamics and nucleosynthesis being pursued at national laboratories here in the United States and by other groups in Europe and Japan. Our calculations show that neutrino production and scattering rate are altered by the nuclear interactions and that these modifications have important implications for nucleosynthesis and terrestrial neutrino detection. The calculation of neutrino rates in dense matter are difficult because nucleons in the dense matter are strongly coupled. A neutrino interacts with several nucleons and the quantum interference between scattering off different nucleons depends on the nature of correlations between them in dense matter. To describe these correlations we used analytic methods based on mean field theory and hydrodynamics, and computational methods such as Quantum Monte Carlo. We found that due to nuclear effects neutrino production rates at relevant temperatures are enhanced, and that electron neutrinos are more easily absorbed than anti-electron neutrinos in dense matter. The latter, was shown to favor synthesis of heavy neutron-rich elements in the supernova.« less

Cloud photogrammetry with dense stereo for fisheye cameras

NASA Astrophysics Data System (ADS)

Beekmans, Christoph; Schneider, Johannes; Läbe, Thomas; Lennefer, Martin; Stachniss, Cyrill; Simmer, Clemens

2016-11-01

We present a novel approach for dense 3-D cloud reconstruction above an area of 10 × 10 km2 using two hemispheric sky imagers with fisheye lenses in a stereo setup. We examine an epipolar rectification model designed for fisheye cameras, which allows the use of efficient out-of-the-box dense matching algorithms designed for classical pinhole-type cameras to search for correspondence information at every pixel. The resulting dense point cloud allows to recover a detailed and more complete cloud morphology compared to previous approaches that employed sparse feature-based stereo or assumed geometric constraints on the cloud field. Our approach is very efficient and can be fully automated. From the obtained 3-D shapes, cloud dynamics, size, motion, type and spacing can be derived, and used for radiation closure under cloudy conditions, for example. Fisheye lenses follow a different projection function than classical pinhole-type cameras and provide a large field of view with a single image. However, the computation of dense 3-D information is more complicated and standard implementations for dense 3-D stereo reconstruction cannot be easily applied. Together with an appropriate camera calibration, which includes internal camera geometry, global position and orientation of the stereo camera pair, we use the correspondence information from the stereo matching for dense 3-D stereo reconstruction of clouds located around the cameras. We implement and evaluate the proposed approach using real world data and present two case studies. In the first case, we validate the quality and accuracy of the method by comparing the stereo reconstruction of a stratocumulus layer with reflectivity observations measured by a cloud radar and the cloud-base height estimated from a Lidar-ceilometer. The second case analyzes a rapid cumulus evolution in the presence of strong wind shear.

Nuclear quantum effects on structure and transport properties of dense liquid helium

NASA Astrophysics Data System (ADS)

Kang, Dongdong; Dai, Jiayu; Yuan, Jianmin

2015-11-01

Transport properties of dense liquid helium under the conditions of planet's core and cool atmosphere of white dwarfs are important for determining the structure and evolution of these astrophysical objects. We have investigated these properties of dense liquid helium by using the improved centroid path-integral simulations combined with density functional theory. The results show that with the inclusion of nuclear quantum effects (NQEs), the self-diffusion is largely higher while the shear viscosity is notably lower than the results of without the inclusion of NQEs due to the lower collision cross sections even when the NQEs have little effects on the static structures. The potential surface of helium atom along the simulation trajectory is quite different between MD and PIMD simulations. We have shown that the quantum nuclear character induces complex behaviors for ionic transport properties of dense liquid helium. NQEs bring more fluctuations of local electronic density of states than the classical treatment. Therefore, in order to construct more reasonable structure and evolution model for the planets and WDs, NQEs must be reconsidered when calculating the transport properties at certain temperature and density conditions.

A high-speed tracking algorithm for dense granular media

NASA Astrophysics Data System (ADS)

Cerda, Mauricio; Navarro, Cristóbal A.; Silva, Juan; Waitukaitis, Scott R.; Mujica, Nicolás; Hitschfeld, Nancy

2018-06-01

Many fields of study, including medical imaging, granular physics, colloidal physics, and active matter, require the precise identification and tracking of particle-like objects in images. While many algorithms exist to track particles in diffuse conditions, these often perform poorly when particles are densely packed together-as in, for example, solid-like systems of granular materials. Incorrect particle identification can have significant effects on the calculation of physical quantities, which makes the development of more precise and faster tracking algorithms a worthwhile endeavor. In this work, we present a new tracking algorithm to identify particles in dense systems that is both highly accurate and fast. We demonstrate the efficacy of our approach by analyzing images of dense, solid-state granular media, where we achieve an identification error of 5% in the worst evaluated cases. Going further, we propose a parallelization strategy for our algorithm using a GPU, which results in a speedup of up to 10 × when compared to a sequential CPU implementation in C and up to 40 × when compared to the reference MATLAB library widely used for particle tracking. Our results extend the capabilities of state-of-the-art particle tracking methods by allowing fast, high-fidelity detection in dense media at high resolutions.

Dense power-law networks and simplicial complexes

NASA Astrophysics Data System (ADS)

Courtney, Owen T.; Bianconi, Ginestra

2018-05-01

There is increasing evidence that dense networks occur in on-line social networks, recommendation networks and in the brain. In addition to being dense, these networks are often also scale-free, i.e., their degree distributions follow P (k ) ∝k-γ with γ ∈(1 ,2 ] . Models of growing networks have been successfully employed to produce scale-free networks using preferential attachment, however these models can only produce sparse networks as the numbers of links and nodes being added at each time step is constant. Here we present a modeling framework which produces networks that are both dense and scale-free. The mechanism by which the networks grow in this model is based on the Pitman-Yor process. Variations on the model are able to produce undirected scale-free networks with exponent γ =2 or directed networks with power-law out-degree distribution with tunable exponent γ ∈(1 ,2 ) . We also extend the model to that of directed two-dimensional simplicial complexes. Simplicial complexes are generalization of networks that can encode the many body interactions between the parts of a complex system and as such are becoming increasingly popular to characterize different data sets ranging from social interacting systems to the brain. Our model produces dense directed simplicial complexes with power-law distribution of the generalized out-degrees of the nodes.

Microgravity fluid management requirements of advanced solar dynamic power systems

NASA Technical Reports Server (NTRS)

Migra, Robert P.

1987-01-01

The advanced solar dynamic system (ASDS) program is aimed at developing the technology for highly efficient, lightweight space power systems. The approach is to evaluate Stirling, Brayton and liquid metal Rankine power conversion systems (PCS) over the temperature range of 1025 to 1400K, identify the critical technologies and develop these technologies. Microgravity fluid management technology is required in several areas of this program, namely, thermal energy storage (TES), heat pipe applications and liquid metal, two phase flow Rankine systems. Utilization of the heat of fusion of phase change materials offers potential for smaller, lighter TES systems. The candidate TES materials exhibit large volume change with the phase change. The heat pipe is an energy dense heat transfer device. A high temperature application may transfer heat from the solar receiver to the PCS working fluid and/or TES. A low temperature application may transfer waste heat from the PCS to the radiator. The liquid metal Rankine PCS requires management of the boiling/condensing process typical of two phase flow systems.

Asymptotic orderings and approximations of the Master kinetic equation for large hard spheres systems

NASA Astrophysics Data System (ADS)

Tessarotto, Massimo; Asci, Claudio

2017-05-01

In this paper the problem is posed of determining the physically-meaningful asymptotic orderings holding for the statistical description of a large N-body system of hard spheres, i.e., formed by N ≡1/ε ≫ 1 particles, which are allowed to undergo instantaneous and purely elastic unary, binary or multiple collisions. Starting point is the axiomatic treatment recently developed [Tessarotto et al., 2013-2016] and the related discovery of an exact kinetic equation realized by Master equation which advances in time the 1-body probability density function (PDF) for such a system. As shown in the paper the task involves introducing appropriate asymptotic orderings in terms of ε for all the physically-relevant parameters. The goal is that of identifying the relevant physically-meaningful asymptotic approximations applicable for the Master kinetic equation, together with their possible relationships with the Boltzmann and Enskog kinetic equations, and holding in appropriate asymptotic regimes. These correspond either to dilute or dense systems and are formed either by small-size or finite-size identical hard spheres, the distinction between the various cases depending on suitable asymptotic orderings in terms of ε.

The relationships between breast volume, breast dense volume and volumetric breast density with body mass index, body fat mass and ethnicity

NASA Astrophysics Data System (ADS)

Zakariyah, N.; Pathy, N. B.; Taib, N. A. M.; Rahmat, K.; Judy, C. W.; Fadzil, F.; Lau, S.; Ng, K. H.

2016-03-01

It has been shown that breast density and obesity are related to breast cancer risk. The aim of this study is to investigate the relationships of breast volume, breast dense volume and volumetric breast density (VBD) with body mass index (BMI) and body fat mass (BFM) for the three ethnic groups (Chinese, Malay and Indian) in Malaysia. We collected raw digital mammograms from 2450 women acquired on three digital mammography systems. The mammograms were analysed using Volpara software to obtain breast volume, breast dense volume and VBD. Body weight, BMI and BFM of the women were measured using a body composition analyser. Multivariable logistic regression was used to determine the independent predictors of increased overall breast volume, breast dense volume and VBD. Indians have highest breast volume and breast dense volume followed by Malays and Chinese. While Chinese are highest in VBD, followed by Malay and Indian. Multivariable analysis showed that increasing BMI and BFM were independent predictors of increased overall breast volume and dense volume. Moreover, BMI and BFM were independently and inversely related to VBD.

Late Quaternary drainage dynamics in northern Brazil based on the study of a large paleochannel from southwestern Marajó Island.

PubMed

Rossetti, Dilce F; Góes, Ana M

2008-09-01

Marajó Island shows an abundance of paleochannels easily mapped in its eastern portion, where vegetation consists mostly of savannas. SRTM data make possible to recognize paleochannels also in western Marajó, even considering the dense forest cover. A well preserved paleodrainage network from the adjacency of the town of Breves (southwestern Marajó Island) was investigated in this work combining remote sensing and sedimentological studies. The palimpsest drainage system consists of a large meander connected to narrower tributaries. Sedimentological studies revealed mostly sharp-based, fining upward sands for the channelized features, and interbedded muds and sands for floodplain areas. The sedimentary structures and facies successions are in perfect agreement with deposition in channelized and floodplain environments, as suggested by remote sensing mapping. The present study shows that this paleodrainage was abandoned during Late Pleistocene, slightly earlier than the Holocene paleochannel systems from the east part of the island. Integration of previous studies with the data available herein supports a tectonic origin, related to the opening of the Pará River along fault lineaments. This would explain the disappearance of large, north to northeastward migrating channel systems in southwestern Marajó Island, which were replaced by the much narrower, south to southeastward flowing modern channels.

Large-Scale Chaos and Fluctuations in Active Nematics

NASA Astrophysics Data System (ADS)

Ngo, Sandrine; Peshkov, Anton; Aranson, Igor S.; Bertin, Eric; Ginelli, Francesco; Chaté, Hugues

2014-07-01

We show that dry active nematics, e.g., collections of shaken elongated granular particles, exhibit large-scale spatiotemporal chaos made of interacting dense, ordered, bandlike structures in a parameter region including the linear onset of nematic order. These results are obtained from the study of both the well-known (deterministic) hydrodynamic equations describing these systems and of the self-propelled particle model they were derived from. We prove, in particular, that the chaos stems from the generic instability of the band solution of the hydrodynamic equations. Revisiting the status of the strong fluctuations and long-range correlations in the particle model, we show that the giant number fluctuations observed in the chaotic phase are a trivial consequence of density segregation. However anomalous, curvature-driven number fluctuations are present in the homogeneous quasiordered nematic phase and characterized by a nontrivial scaling exponent.

Automatic determination of 3D orientations of fossilized oyster shells from a densely packed Miocene shell bed

NASA Astrophysics Data System (ADS)

Puttonen, Ana; Harzhauser, Mathias; Puttonen, Eetu; Mandic, Oleg; Székely, Balázs; Molnár, Gábor; Pfeifer, Norbert

2018-02-01

Shell beds represent a useful source of information on various physical processes that cause the depositional condition. We present an automated method to calculate the 3D orientations of a large number of elongate and platy objects (fossilized oyster shells) on a sedimentary bedding plane, developed to support the interpretation of possible depositional patterns, imbrications, or impact of local faults. The study focusses on more than 1900 fossil oyster shells exposed in a densely packed Miocene shell bed. 3D data were acquired by terrestrial laser scanning on an area of 459 m2 with a resolution of 1 mm. Bivalve shells were manually defined as 3D-point clouds of a digital surface model and stored in an ArcGIS database. An individual shell coordinate system (ISCS) was virtually embedded into each shell and its orientation was determined relative to the coordinate system of the entire, tectonically tilted shell bed. Orientation is described by the rotation angles roll, pitch, and yaw in a Cartesian coordinate system. This method allows an efficient measurement and analysis of the orientation of thousands of specimens and is a major advantage compared to the traditional 2D approach, which measures only the azimuth (yaw) angles. The resulting data can variously be utilized for taphonomic analyses and the reconstruction of prevailing hydrodynamic regimes and depositional environments. For the first time, the influence of possible post-sedimentary vertical displacements can be quantified with high accuracy. Here, the effect of nearby fault lines—present in the reef—was tested on strongly tilted oyster shells, but it was found out that the fault lines did not have a statistically significant effect on the large tilt angles. Aside from the high reproducibility, a further advantage of the method is its non-destructive nature, which is especially suitable for geoparks and protected sites such as the studied shell bed.

Self-compensating design for reduction of timing and leakage sensitivity to systematic pattern dependent variation

NASA Astrophysics Data System (ADS)

Gupta, Puneet; Kahng, Andrew B.; Kim, Youngmin; Sylvester, Dennis

2006-03-01

Focus is one of the major sources of linewidth variation. CD variation caused by defocus is largely systematic after the layout is finished. In particular, dense lines "smile" through focus while isolated lines "frown" in typical Bossung plots. This well-defined systematic behavior of focus-dependent CD variation allows us to develop a self-compensating design methodology. In this work, we propose a novel design methodology that allows explicit compensation of focus-dependent CD variation, either within a cell (self-compensated cells) or across cells in a critical path (self-compensated design). By creating iso and dense variants for each library cell, we can achieve designs that are more robust to focus variation. Optimization with a mixture of iso and dense cell variants is possible both for area and leakage power, with the latter providing an interesting complement to existing leakage reduction techniques such as dual-Vth. We implement both heuristic and Mixed-Integer Linear Programming (MILP) solution methods to address this optimization, and experimentally compare their results. Our results indicate that designing with a self-compensated cell library incurs ~12% area penalty and ~6% leakage increase over original layouts while compensating for focus-dependent CD variation (i.e., the design meets timing constraints across a large range of focus variation). We observe ~27% area penalty and ~7% leakage increase at the worst-case defocus condition using only single-pitch cells. The area penalty of circuits after using either the heuristic or MILP optimization approach is reduced to ~3% while maintaining timing. We also apply our optimizations to leakage, which traditionally shows very large variability due to its exponential relationship with gate CD. We conclude that a mixed iso/dense library combined with a sensitivity-based optimization approach yields much better area/timing/leakage tradeoffs than using a self-compensated cell library alone. Self-compensated design shows an average of 25% leakage reduction at the worst defocus condition for the benchmark designs that we have studied.

Active acoustical impedance using distributed electrodynamical transducers.

PubMed

Collet, M; David, P; Berthillier, M

2009-02-01

New miniaturization and integration capabilities available from emerging microelectromechanical system (MEMS) technology will allow silicon-based artificial skins involving thousands of elementary actuators to be developed in the near future. SMART structures combining large arrays of elementary motion pixels coated with macroscopic components are thus being studied so that fundamental properties such as shape, stiffness, and even reflectivity of light and sound could be dynamically adjusted. This paper investigates the acoustic impedance capabilities of a set of distributed transducers connected with a suitable controlling strategy. Research in this domain aims at designing integrated active interfaces with a desired acoustical impedance for reaching an appropriate global acoustical behavior. This generic problem is intrinsically connected with the control of multiphysical systems based on partial differential equations (PDEs) and with the notion of multiscaled physics when a dense array of electromechanical systems (or MEMS) is considered. By using specific techniques based on PDE control theory, a simple boundary control equation capable of annihilating the wave reflections has been built. The obtained strategy is also discretized as a low order time-space operator for experimental implementation by using a dense network of interlaced microphones and loudspeakers. The resulting quasicollocated architecture guarantees robustness and stability margins. This paper aims at showing how a well controlled semidistributed active skin can substantially modify the sound transmissibility or reflectivity of the corresponding homogeneous passive interface. In Sec. IV, numerical and experimental results demonstrate the capabilities of such a method for controlling sound propagation in ducts. Finally, in Sec. V, an energy-based comparison with a classical open-loop strategy underlines the system's efficiency.

Full duplex dense-wavelength-division-multiplexing radio-over-fiber system transmission of 75-GHz W-band frequency multiple-input multiple-output orthogonal-frequency-division-multiplexing signals with 3×12 Gbps downstream and 6 Gbps upstream

NASA Astrophysics Data System (ADS)

Fang, Wei Jin; Huang, Xu Guang; Yang, Kai; Zhang, Xiao Min

2012-09-01

We propose and demonstrate a full duplex dense-wavelength-division-multiplexing radio-over-fiber (DWDM-ROF) system for transmitting 75-GHz W-band frequency multiple-input multiple-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) signals with 12 Gbps downstream and 6 Gbps upstream. The downstream transmitting terminal is based on a three-channels sextupling-frequency scheme using an external modulation of a distributed feedback laser diode (DFB-LD) and dual drive Mach-Zehnder modulator (DD-MZM) for carrying downstream signals. MIMO-OFDM algorithms effectively compensate for impairments in the wireless link. Without using costly W-band components in the transmitter, a 12 Gbps downstream transmission system operation at 75 GHz is experimentally validated. For the downstream transmission, a power penalty of less than 3 dB was observed after a 50 km single mode fiber (SMF) and 4 m wireless transmission at a bit error rate (BER) of 3.8×10-3. For the upstream transmission, we use a commercially available 1.5 GHz bandwidth reflective semiconductor optical amplifier (RSOA) to achieve 6 Gbps upstream traffic for 16 QAM-OFDM signals. A power penalty of 3 dB was observed after a 50 km SMF transmission at a BER of 3.8×10-3. The frequency of the local oscillator is reduced due to the frequency sextupling scheme. The cost of the proposed system is largely reduced.

SU-C-207B-04: Automated Segmentation of Pectoral Muscle in MR Images of Dense Breasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verburg, E; Waard, SN de; Veldhuis, WB

Purpose: To develop and evaluate a fully automated method for segmentation of the pectoral muscle boundary in Magnetic Resonance Imaging (MRI) of dense breasts. Methods: Segmentation of the pectoral muscle is an important part of automatic breast image analysis methods. Current methods for segmenting the pectoral muscle in breast MRI have difficulties delineating the muscle border correctly in breasts with a large proportion of fibroglandular tissue (i.e., dense breasts). Hence, an automated method based on dynamic programming was developed, incorporating heuristics aimed at shape, location and gradient features.To assess the method, the pectoral muscle was segmented in 91 randomly selectedmore » participants (mean age 56.6 years, range 49.5–75.2 years) from a large MRI screening trial in women with dense breasts (ACR BI-RADS category 4). Each MR dataset consisted of 178 or 179 T1-weighted images with voxel size 0.64 × 0.64 × 1.00 mm3. All images (n=16,287) were reviewed and scored by a radiologist. In contrast to volume overlap coefficients, such as DICE, the radiologist detected deviations in the segmented muscle border and determined whether the result would impact the ability to accurately determine the volume of fibroglandular tissue and detection of breast lesions. Results: According to the radiologist’s scores, 95.5% of the slices did not mask breast tissue in such way that it could affect detection of breast lesions or volume measurements. In 13.1% of the slices a deviation in the segmented muscle border was present which would not impact breast lesion detection. In 70 datasets (78%) at least 95% of the slices were segmented in such a way it would not affect detection of breast lesions, and in 60 (66%) datasets this was 100%. Conclusion: Dynamic programming with dedicated heuristics shows promising potential to segment the pectoral muscle in women with dense breasts.« less

Time-resolved large-scale volumetric pressure fields of an impinging jet from dense Lagrangian particle tracking

NASA Astrophysics Data System (ADS)

Huhn, F.; Schanz, D.; Manovski, P.; Gesemann, S.; Schröder, A.

2018-05-01

Time-resolved volumetric pressure fields are reconstructed from Lagrangian particle tracking with high seeding concentration using the Shake-The-Box algorithm in a perpendicular impinging jet flow with exit velocity U=4 m/s (Re˜ 36,000) and nozzle-plate spacing H/D=5. Helium-filled soap bubbles are used as tracer particles which are illuminated with pulsed LED arrays. A large measurement volume has been covered (cloud of tracked particles in a volume of 54 L, ˜ 180,000 particles). The reconstructed pressure field has been validated against microphone recordings at the wall with high correlation coefficients up to 0.88. In a reduced measurement volume (13 L), dense Lagrangian particle tracking is shown to be feasable up to the maximal possible jet velocity of U=16 m/s.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliver, R.; Soler, R.; Terradas, J.

Observations of active regions and limb prominences often show cold, dense blobs descending with an acceleration smaller than that of free fall. The dynamics of these condensations falling in the solar corona is investigated in this paper using a simple fully ionized plasma model. We find that the presence of a heavy condensation gives rise to a dynamical rearrangement of the coronal pressure that results in the formation of a large pressure gradient that opposes gravity. Eventually this pressure gradient becomes so large that the blob acceleration vanishes or even points upward. Then, the blob descent is characterized by anmore » initial acceleration phase followed by an essentially constant velocity phase. These two stages can be identified in published time-distance diagrams of coronal rain events. Both the duration of the first stage and the velocity attained by the blob increase for larger values of the ratio of blob to coronal density, for larger blob mass, and for smaller coronal temperature. Dense blobs are characterized by a detectable density growth (up to 60% in our calculations) and by a steepening of the density in their lower part, that could lead to the formation of a shock. They also emit sound waves that could be detected as small intensity changes with periods of the order of 100 s and lasting between a few and about 10 periods. Finally, the curvature of falling paths with large radii is only relevant when a very dense blob falls along inclined magnetic field lines.« less

Prediction-based association control scheme in dense femtocell networks.

PubMed

Sung, Nak Woon; Pham, Ngoc-Thai; Huynh, Thong; Hwang, Won-Joo; You, Ilsun; Choo, Kim-Kwang Raymond

2017-01-01

The deployment of large number of femtocell base stations allows us to extend the coverage and efficiently utilize resources in a low cost manner. However, the small cell size of femtocell networks can result in frequent handovers to the mobile user, and consequently throughput degradation. Thus, in this paper, we propose predictive association control schemes to improve the system's effective throughput. Our design focuses on reducing handover frequency without impacting on throughput. The proposed schemes determine handover decisions that contribute most to the network throughput and are proper for distributed implementations. The simulation results show significant gains compared with existing methods in terms of handover frequency and network throughput perspective.

Calcified pilocytic astrocytoma of the medulla mimicking a brainstem "stone".

PubMed

Berhouma, M; Jemel, H; Kchir, N

2008-10-01

Brainstem gliomas are a heterogeneous group of tumours commonly found in children, comprising about 10% of central nervous system tumours in paediatric patients, but less than 2% in adults. Pilocytic astrocytomas usually involve the midbrain and the medulla, and their surgical resection, when feasible, is generally curative. Thin calcifications can be normally found within low grade gliomas, but densely calcified pilocytic astrocytomas of the brainstem have been only rarely reported. We present the case of a young man presenting with a large brainstem calcification involving the medulla, which was subtotally resected using a posterior suboccipital approach. The definitive pathological diagnosis was calcified pilocytic astrocytoma.

Satellite relay telemetry of seismic data in earthquake prediction and control

USGS Publications Warehouse

Jackson, Wayne H.; Eaton, Jerry P.

1971-01-01

The Satellite Telemetry Earthquake Monitoring Program was started in FY 1968 to evaluate the applicability of satellite relay telemetry in the collection of seismic data from a large number of dense seismograph clusters laid out along the major fault systems of western North America. Prototype clusters utilizing phone-line telemetry were then being installed by the National Center for Earthquake Research (NCER) in 3 regions along the San Andreas fault in central California; and the experience of installing and operating the clusters and in reducing and analyzing the seismic data from them was to provide the raw materials for evaluation in the satellite relay telemetry project.

Simulation of dense amorphous polymers by generating representative atomistic models

NASA Astrophysics Data System (ADS)

Curcó, David; Alemán, Carlos

2003-08-01

A method for generating atomistic models of dense amorphous polymers is presented. The generated models can be used as starting structures of Monte Carlo and molecular dynamics simulations, but also are suitable for the direct evaluation physical properties. The method is organized in a two-step procedure. First, structures are generated using an algorithm that minimizes the torsional strain. After this, an iterative algorithm is applied to relax the nonbonding interactions. In order to check the performance of the method we examined structure-dependent properties for three polymeric systems: polyethyelene (ρ=0.85 g/cm3), poly(L,D-lactic) acid (ρ=1.25 g/cm3), and polyglycolic acid (ρ=1.50 g/cm3). The method successfully generated representative packings for such dense systems using minimum computational resources.

Seeing the Forest Through the Trees: The Distribution and Properties of Dense Molecular Gas in the Milky Way Galaxy

NASA Astrophysics Data System (ADS)

Ellsworth-Bowers, Timothy P.

The Milky Way Galaxy serves as a vast laboratory for studying the dynamics and evolution of the dense interstellar medium and the processes of and surrounding massive star formation. From our vantage point within the Galactic plane, however, it has been extremely difficult to construct a coherent picture of Galactic structure; we cannot see the forest for the trees. The principal difficulties in studying the structure of the Galactic disk have been obscuration by the ubiquitous dust and molecular gas and confusion between objects along a line of sight. Recent technological advances have led to large-scale blind surveys of the Galactic plane at (sub-)millimeter wavelengths, where Galactic dust is generally optically thin, and have opened a new avenue for studying the forest. The Bolocam Galactic Plane Survey (BGPS) observed over 190 deg 2 of the Galactic plane in dust continuum emission near lambda = 1.1 mm, producing a catalog of over 8,000 dense molecular cloud structures across a wide swath of the Galactic disk. Deriving the spatial distribution and physical properties of these objects requires knowledge of distance, a component lacking in the data themselves. This thesis presents a generalized Bayesian probabilistic distance estimation method for dense molecular cloud structures, and demonstrates it with the BGPS data set. Distance probability density functions (DPDFs) are computed from kinematic distance likelihoods (which may be double- peaked for objects in the inner Galaxy) and an expandable suite of prior information to produce a comprehensive tally of our knowledge (and ignorance) of the distances to dense molecular cloud structures. As part of the DPDF formalism, this thesis derives several prior DPDFs for resolving the kinematic distance ambiguity in the inner Galaxy. From the collection of posterior DPDFs, a set of objects with well-constrained distance estimates is produced for deriving Galactic structure and the physical properties of dense molecular cloud structures. This distance catalog of 1,802 objects across the Galactic plane represents the first large-scale analysis of clump-scale objects in a variety of Galactic environments. The Galactocentric positions of these objects begin to trace out the spiral structure of the Milky Way, and suggest that dense molecular gas settles nearer the Galactic midplane than tracers of less-dense gas such as CO. Physical properties computed from the DPDFs reveal that BGPS objects trace a continuum of scales within giant molecular clouds, and extend the scaling relationships known as Larson's Laws to lower-mass substructures. The results presented here represent the first step on the road to seeing the molecular content of the Milky Way as a forest rather than individual nearby trees.

Urban ventilation corridors mapping using surface morphology data based GIS analysis

NASA Astrophysics Data System (ADS)

Wicht, Marzena; Wicht, Andreas; Osińska-Skotak, Katarzyna

2017-04-01

This paper describes deriving the most appropriate method for mapping urban ventilation corridors, which, if properly designed, reduce heat stress, air pollution and increase air quality, as well as increase the horizontal wind speed. Urban areas are - in terms of surface texture - recognized as one of the roughest surfaces, which results in wind obstruction and decreased ventilation of densely built up areas. As urban heat islands, private household and traffic emissions or large scale industries occur frequently in many cities, both in temperate and tropical regions. A proper ventilation system has been suggested as an appropriate mitigation mean [1] . Two concepts of morphometric analyses of the urban environment are used on the example of Warsaw, representing a dense, urban environment, located in the temperate zone. The utilized methods include firstly a roughness mapping calculation [2] , which analyses zero plane displacement height (zd) and roughness length (z0) and their distribution for the eight (inter-)cardinal wind directions and secondly a grid-based frontal area index mapping approach [3] , which uses least cost path analysis. Utilizing the advantages and minimizing the disadvantages of those two concepts, we propose a hybrid approach. All concepts are based on a 3D building database obtained from satellite imagery, aided by a cadastral building database. Derived areas (ventilation corridors), that facilitate the ventilation system, should be considered by the local authorities as worth preserving, if not expanding, in order to improve the air quality in the city. The results also include designation of the problematic areas, which greatly obscure the ventilation and might be investigated as to reshape or rebuilt to introduce the air flow in particularly dense areas like city centers. Keywords: roughness mapping; GIS; ventilation corridors; frontal area index Rizwan, A. M., Dennis, L. Y., & Chunho, L. I. U. (2008). A review on the generation, determination and mitigation of Urban Heat Island. Journal of Environmental Sciences, 20(1), 120-128. Gál, T., & Unger, J. (2009). Detection of ventilation paths using high-resolution roughness parameter mapping in a large urban area. Building and Environment, 44(1), 198-206. Wong, M. S., Nichol, J. E., To, P. H., & Wang, J. (2010). A simple method for designation of urban ventilation corridors and its application to urban heat island analysis. Building and Environment, 45(8), 1880-1889.

Preliminary Geophysical Investigations of the Ship Rock Diatreme, Navajo Nation, New Mexico

NASA Astrophysics Data System (ADS)

Gruen, E. M.; McCarthy, L.; Namingha, G.; Bank, C.; Noblett, J.; Semken, S.

2003-12-01

Magnetic and gravity data were collected at the Ship Rock minette neck and dikes, part of the Navajo volcanic field in the central Colorado Plateau, to investigate their subsurface structure. The deep root system of Ship Rock, an exhumed Oligocene maar-diatreme complex, has not been resolved. The diatreme is largely composed of minette tuff-breccia with a large wallrock fraction, whereas the dikes are composed of hypabyssal minette. The country rock is the Upper Cretaceous Mancos Shale. Density and magnetic contrasts between the igneous rock and surrounding shale suggest that the buried structure of Ship Rock can be imaged. Preliminary geophysical investigations were carried out in order to test this hypothesis. We collected magnetic and gravitational data along four lines selected to transect the major south and northeast dikes and to partly encircle the diatreme. Modeling differently sized, oriented and shaped intrusions, we created theoretical Free Air anomaly curves to try to match the two clearest anomalies. Modeling necessitates (i) that the major north-south dike dips west and (ii) the presence of a high-density, deep body near the diatreme. The Free Air anomaly curves show that smaller dikes might not be detected from gravity data; however, they are necessary to determine the presence of large, dense bodies. Although not modeled, the magnetics curves show that smaller dikes can easily be detected. Our study results are promising, and we plan a more thorough investigation in the future which will produce a magnetic map to determine if further buried dikes exist in the vicinity, and measure gravity along additional profiles to better constrain the location of the dense body at depth.

Open Heavy Flavor and Quarkonia Results at RHIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nouicer, Rachid

RHIC experiments carry out a comprehensive physics program which studies open heavy flavor and quarkonium production in relativistic heavy-ion collisions. The discovery at RHIC of large high-pT suppression and flow of electrons from heavy quarks flavors have altered our view of the hot and dense matter formed in central Au + Au collisions at √S NN = 200 GeV. These results suggest a large energy loss and flow of heavy quarks in the hot, dense matter. In recent years, the RHIC experiments upgraded the detectors; (1) PHENIX Collaboration installed silicon vertex tracker (VTX) at mid-rapidity region and forward silicon vertexmore » tracker (FVTX) at the forward rapidity region, and (2) STAR Collaboration installed the heavy flavor tracker (HFT) and the muon telescope detector (MTD) both at the mid-rapidity region. With these new upgrades, both experiments have collected large data samples. These new detectors enhance the capability of heavy flavor measurements via precision tracking. The PHENIX experiments established measurements of ψ(1S) and ψ(2S) production as a function of system size, p + p, p + Al, p + Au, and 3He + Au collisions at √S NN = 200 GeV. In p/ 3He + A collisions at forward rapidity, we observe no difference in the ψ(2S)/ψ(1S) ratio relative to p + p collisions. At backward rapidity, where the comoving particle density is higher, we find that the ψ(2S) is preferentially suppressed by a factor of two. STAR Collaboration presents the first J/ψ and Υ measurements in the di-muon decay channel in Au + Au collisions at GeV at mid-rapidity at RHIC. Here, we observe clear J/ψ RAA suppression and qualitatively well described by transport models simultaneously accounting for dissociation and regeneration processes.« less

Open Heavy Flavor and Quarkonia Results at RHIC

NASA Astrophysics Data System (ADS)

Nouicer, Rachid

2017-12-01

RHIC experiments carry out a comprehensive physics program which studies open heavy flavor and quarkonium production in relativistic heavy-ion collisions. The discovery at RHIC of large high-pT suppression and flow of electrons from heavy quarks flavors have altered our view of the hot and dense matter formed in central Au + Au collisions at GeV. These results suggest a large energy loss and flow of heavy quarks in the hot, dense matter. In recent years, the RHIC experiments upgraded the detectors; (1) PHENIX Collaboration installed silicon vertex tracker (VTX) at mid-rapidity region and forward silicon vertex tracker (FVTX) at the forward rapidity region, and (2) STAR Collaboration installed the heavy flavor tracker (HFT) and the muon telescope detector (MTD) both at the mid-rapidity region. With these new upgrades, both experiments have collected large data samples. These new detectors enhance the capability of heavy flavor measurements via precision tracking. The PHENIX experiments established measurements of ψ(1S) and ψ(2S) production as a function of system size, p + p, p + Al, p + Au, and 3He + Au collisions at GeV. In p/3He + A collisions at forward rapidity, we observe no difference in the ψ(2S)/ψ(1S) ratio relative to p + p collisions. At backward rapidity, where the comoving particle density is higher, we find that the ψ(2S) is preferentially suppressed by a factor of two. STAR Collaboration presents the first J/ψ and ϒ measurements in the di-muon decay channel in Au + Au collisions at GeV at mid-rapidity at RHIC. We observe clear J/ψ RAA suppression and qualitatively well described by transport models simultaneously accounting for dissociation and regeneration processes.

Open Heavy Flavor and Quarkonia Results at RHIC

DOE PAGES

Nouicer, Rachid

2017-12-05

RHIC experiments carry out a comprehensive physics program which studies open heavy flavor and quarkonium production in relativistic heavy-ion collisions. The discovery at RHIC of large high-pT suppression and flow of electrons from heavy quarks flavors have altered our view of the hot and dense matter formed in central Au + Au collisions at √S NN = 200 GeV. These results suggest a large energy loss and flow of heavy quarks in the hot, dense matter. In recent years, the RHIC experiments upgraded the detectors; (1) PHENIX Collaboration installed silicon vertex tracker (VTX) at mid-rapidity region and forward silicon vertexmore » tracker (FVTX) at the forward rapidity region, and (2) STAR Collaboration installed the heavy flavor tracker (HFT) and the muon telescope detector (MTD) both at the mid-rapidity region. With these new upgrades, both experiments have collected large data samples. These new detectors enhance the capability of heavy flavor measurements via precision tracking. The PHENIX experiments established measurements of ψ(1S) and ψ(2S) production as a function of system size, p + p, p + Al, p + Au, and 3He + Au collisions at √S NN = 200 GeV. In p/ 3He + A collisions at forward rapidity, we observe no difference in the ψ(2S)/ψ(1S) ratio relative to p + p collisions. At backward rapidity, where the comoving particle density is higher, we find that the ψ(2S) is preferentially suppressed by a factor of two. STAR Collaboration presents the first J/ψ and Υ measurements in the di-muon decay channel in Au + Au collisions at GeV at mid-rapidity at RHIC. Here, we observe clear J/ψ RAA suppression and qualitatively well described by transport models simultaneously accounting for dissociation and regeneration processes.« less

Adaptations in the structure and innervation of follicle-sinus complexes to an aquatic environment as seen in the Florida manatee (Trichechus manatus latirostris).

PubMed

Sarko, Diana K; Reep, Roger L; Mazurkiewicz, Joseph E; Rice, Frank L

2007-09-20

Florida manatees are large-bodied aquatic herbivores that use large tactile vibrissae for several purposes. Facial vibrissae are used to forage in a turbid water environment, and the largest perioral vibrissae can also grasp and manipulate objects. Other vibrissae distributed over the entire postfacial body appear to function as a lateral line system. All manatee vibrissae emanate from densely innervated follicle-sinus complexes (FSCs) like those in other mammals, although proportionately larger commensurate with the caliber of the vibrissae. As revealed by immunofluorescence, all manatee FSCs have many types of C, Adelta and Abeta innervation including Merkel, club, and longitudinal lanceolate endings at the level of the ring sinus, but they lack other types such as reticular and spiny endings at the level of the cavernous sinus. As in non-whisking terrestrial species, the inner conical bodies of facial FSCs are well innervated but lack Abeta-fiber terminals. Importantly, manatee FSCs have two unique types of Abeta-fiber endings. First, all of the FSCs have exceptionally large-caliber axons that branch to terminate as novel, gigantic spindle-like endings located at the upper ring sinus. Second, facial FSCs have smaller caliber Abeta fibers that terminate in the trabeculae of the cavernous sinus as an ending that resembles a Golgi tendon organ. In addition, the largest perioral vibrissae, which are used for grasping, have exceptionally well-developed medullary cores that have a structure and dense small-fiber innervation resembling that of tooth pulp. Other features of the epidermis and upper dermis structure and innervation differ from that seen in terrestrial mammals. Copyright (c) 2007 Wiley-Liss, Inc.

The roles of large top predators in coastal ecosystems: new insights from long term ecological research

USGS Publications Warehouse

Rosenblatt, Adam E.; Heithaus, Michael R.; Mather, Martha E.; Matich, Philip; Nifong, James C.; Ripple, William J.; Silliman, Brian R.

2013-01-01

During recent human history, human activities such as overhunting and habitat destruction have severely impacted many large top predator populations around the world. Studies from a variety of ecosystems show that loss or diminishment of top predator populations can have serious consequences for population and community dynamics and ecosystem stability. However, there are relatively few studies of the roles of large top predators in coastal ecosystems, so that we do not yet completely understand what could happen to coastal areas if large top predators are extirpated or significantly reduced in number. This lack of knowledge is surprising given that coastal areas around the globe are highly valued and densely populated by humans, and thus coastal large top predator populations frequently come into conflict with coastal human populations. This paper reviews what is known about the ecological roles of large top predators in coastal systems and presents a synthesis of recent work from three coastal eastern US Long Term Ecological Research (LTER) sites where long-term studies reveal what appear to be common themes relating to the roles of large top predators in coastal systems. We discuss three specific themes: (1) large top predators acting as mobile links between disparate habitats, (2) large top predators potentially affecting nutrient and biogeochemical dynamics through localized behaviors, and (3) individual specialization of large top predator behaviors. We also discuss how research within the LTER network has led to enhanced understanding of the ecological roles of coastal large top predators. Highlighting this work is intended to encourage further investigation of the roles of large top predators across diverse coastal aquatic habitats and to better inform researchers and ecosystem managers about the importance of large top predators for coastal ecosystem health and stability.

Composition design for Laves phase-related body-centered cubic-V solid solution alloys with large hydrogen storage capacities.

PubMed

Wang, H B; Wang, Q; Dong, C; Yuan, L; Xu, F; Sun, L X

2008-03-19

This paper analyzes the characteristics of alloy compositions with large hydrogen storage capacities in Laves phase-related body-centered cubic (bcc) solid solution alloy systems using the cluster line approach. Since a dense-packed icosahedral cluster A(6)B(7) characterizes the local structure of AB(2) Laves phases, in an A-B-C ternary system, such as Ti-Cr (Mn, Fe)-V, where A-B forms AB(2) Laves phases while A-C and B-C tend to form solid solutions, a cluster line A(6)B(7)-C is constructed by linking A(6)B(7) to C. The alloy compositions with large hydrogen storage capacities are generally located near this line and are approximately expressed with the cluster-plus-glue-atom model. The cluster line alloys (Ti(6)Cr(7))(100-x)V(x) (x = 2.5-70 at.%) exhibit different structures and hence different hydrogen storage capacities with increasing V content. The alloys (Ti(6)Cr(7))(95)V(5) and Ti(30)Cr(40)V(30) with bcc solid solution structure satisfy the cluster-plus-glue-atom model.

High-efficiency wavefunction updates for large scale Quantum Monte Carlo

NASA Astrophysics Data System (ADS)

Kent, Paul; McDaniel, Tyler; Li, Ying Wai; D'Azevedo, Ed

Within ab intio Quantum Monte Carlo (QMC) simulations, the leading numerical cost for large systems is the computation of the values of the Slater determinants in the trial wavefunctions. The evaluation of each Monte Carlo move requires finding the determinant of a dense matrix, which is traditionally iteratively evaluated using a rank-1 Sherman-Morrison updating scheme to avoid repeated explicit calculation of the inverse. For calculations with thousands of electrons, this operation dominates the execution profile. We propose a novel rank- k delayed update scheme. This strategy enables probability evaluation for multiple successive Monte Carlo moves, with application of accepted moves to the matrices delayed until after a predetermined number of moves, k. Accepted events grouped in this manner are then applied to the matrices en bloc with enhanced arithmetic intensity and computational efficiency. This procedure does not change the underlying Monte Carlo sampling or the sampling efficiency. For large systems and algorithms such as diffusion Monte Carlo where the acceptance ratio is high, order of magnitude speedups can be obtained on both multi-core CPU and on GPUs, making this algorithm highly advantageous for current petascale and future exascale computations.

Bubbling in vibrated granular films.

PubMed

Zamankhan, Piroz

2011-02-01

With the help of experiments, computer simulations, and a theoretical investigation, a general model is developed of the flow dynamics of dense granular media immersed in air in an intermediate regime where both collisional and frictional interactions may affect the flow behavior. The model is tested using the example of a system in which bubbles and solid structures are produced in granular films shaken vertically. Both experiments and large-scale, three-dimensional simulations of this system are performed. The experimental results are compared with the results of the simulation to verify the validity of the model. The data indicate evidence of formation of bubbles when peak acceleration relative to gravity exceeds a critical value Γ(b). The air-grain interfaces of bubblelike structures are found to exhibit fractal structure with dimension D=1.7±0.05.

The Formation of Complex Organic Compounds in Astrophysical Ices and their Implications for Astrobiology

NASA Technical Reports Server (NTRS)

Sandford, Scott A.

2015-01-01

Ices in astrophysical environments are generally dominated by very simple molecules like H2O, CH3OH, CH4, NH3, CO, CO2, etc, although they likely contain PAHs as well. These molecules, particularly H2O, are of direct interest to astrobiology in-and-of themselves since they represent some of the main carriers of the biogenic elements C, H, O, and N. In addition, these compounds are present in the dense interstellar clouds in which new stars and planetary systems are formed and may play a large role in the delivery of volatiles and organics to the surfaces of new planets. However, these molecules are all far simpler than the more complex organic compounds found in living systems.

Expansion and improvement of the FORMA system for response and load analysis. Volume 2A: Listings, dense FORMA subroutines

NASA Technical Reports Server (NTRS)

Wohlen, R. L.

1976-01-01

A listing of the source deck of each dense FORMA subroutine is given to remove the 'black-box' aura of the subroutines so that the analyst may better understand the detail operations of each subroutine. The FORTRAN 4 programming language is used throughout.

A Plasma Ultraviolet Source for Short Wavelength Lasers.

DTIC Science & Technology

1986-03-10

A high power blue-green laser was pumped with an array of the dense plasma focus . As the result of optimizing the operating conditions of the dense... plasma focus and laser system, the maximum untuned laser output exceeded 2.lmJ corresponding to the energy density 3J/cu cm which is much higher than

A systematic method of interconnection optimization for dense-array concentrator photovoltaic system.

PubMed

Siaw, Fei-Lu; Chong, Kok-Keong

2013-01-01

This paper presents a new systematic approach to analyze all possible array configurations in order to determine the most optimal dense-array configuration for concentrator photovoltaic (CPV) systems. The proposed method is fast, simple, reasonably accurate, and very useful as a preliminary study before constructing a dense-array CPV panel. Using measured flux distribution data, each CPV cells' voltage and current values at three critical points which are at short-circuit, open-circuit, and maximum power point are determined. From there, an algorithm groups the cells into basic modules. The next step is I-V curve prediction, to find the maximum output power of each array configuration. As a case study, twenty different I-V predictions are made for a prototype of nonimaging planar concentrator, and the array configuration that yields the highest output power is determined. The result is then verified by assembling and testing of an actual dense-array on the prototype. It was found that the I-V curve closely resembles simulated I-V prediction, and measured maximum output power varies by only 1.34%.

A Systematic Method of Interconnection Optimization for Dense-Array Concentrator Photovoltaic System

PubMed Central

Siaw, Fei-Lu

2013-01-01

This paper presents a new systematic approach to analyze all possible array configurations in order to determine the most optimal dense-array configuration for concentrator photovoltaic (CPV) systems. The proposed method is fast, simple, reasonably accurate, and very useful as a preliminary study before constructing a dense-array CPV panel. Using measured flux distribution data, each CPV cells' voltage and current values at three critical points which are at short-circuit, open-circuit, and maximum power point are determined. From there, an algorithm groups the cells into basic modules. The next step is I-V curve prediction, to find the maximum output power of each array configuration. As a case study, twenty different I-V predictions are made for a prototype of nonimaging planar concentrator, and the array configuration that yields the highest output power is determined. The result is then verified by assembling and testing of an actual dense-array on the prototype. It was found that the I-V curve closely resembles simulated I-V prediction, and measured maximum output power varies by only 1.34%. PMID:24453823

How to form planetesimals from mm-sized chondrules and chondrule aggregates

NASA Astrophysics Data System (ADS)

Carrera, Daniel; Johansen, Anders; Davies, Melvyn B.

2015-07-01

The size distribution of asteroids and Kuiper belt objects in the solar system is difficult to reconcile with a bottom-up formation scenario due to the observed scarcity of objects smaller than ~100 km in size. Instead, planetesimals appear to form top-down, with large 100-1000 km bodies forming from the rapid gravitational collapse of dense clumps of small solid particles. In this paper we investigate the conditions under which solid particles can form dense clumps in a protoplanetary disk. We used a hydrodynamic code to model the interaction between solid particles and the gas inside a shearing box inside the disk, considering particle sizes from submillimeter-sized chondrules to meter-sized rocks. We found that particles down to millimeter sizes can form dense particle clouds through the run-away convergence of radial drift known as the streaming instability. We made a map of the range of conditions (strength of turbulence, particle mass-loading, disk mass, and distance to the star) that are prone to producing dense particle clumps. Finally, we estimate the distribution of collision speeds between mm-sized particles. We calculated the rate of sticking collisions and obtain a robust upper limit on the particle growth timescale of ~105 years. This means that mm-sized chondrule aggregates can grow on a timescale much smaller than the disk accretion timescale (~106-107 years). Our results suggest a pathway from the mm-sized grains found in primitive meteorites to fully formed asteroids. We speculate that asteroids may form from a positive feedback loop in which coagualation leads to particle clumping driven by the streaming instability. This clumping, in turn, reduces collision speeds and enhances coagulation. Future simulations should model coagulation and the streaming instability together to explore this feedback loop further. Appendices are available in electronic form at http://www.aanda.org

The Dense Molecular Gas and Nuclear Activity in the ULIRG IRAS 13120–5453

DOE Office of Scientific and Technical Information (OSTI.GOV)

Privon, G. C.; Treister, E.; Aalto, S.

2017-02-01

We present new Atacama Large Millimeter/submillimeter Array Band 7 (∼340 GHz) observations of the dense gas tracers HCN, HCO{sup +}, and CS in the local, single-nucleus, ultraluminous infrared galaxy IRAS 13120–5453. We find centrally enhanced HCN (4–3) emission, relative to HCO{sup +} (4–3), but do not find evidence for radiative pumping of HCN. Considering the size of the starburst (0.5 kpc) and the estimated supernovae rate of ∼1.2 yr{sup −1}, the high HCN/HCO{sup +} ratio can be explained by an enhanced HCN abundance as a result of mechanical heating by the supernovae, though the active galactic nucleus and winds maymore » also contribute additional mechanical heating. The starburst size implies a high Σ{sub IR} of 4.7 × 10{sup 12} L {sub ⊙} kpc{sup −2}, slightly below predictions of radiation-pressure limited starbursts. The HCN line profile has low-level wings, which we tentatively interpret as evidence for outflowing dense molecular gas. However, the dense molecular outflow seen in the HCN line wings is unlikely to escape the Galaxy and is destined to return to the nucleus and fuel future star formation. We also present modeling of Herschel observations of the H{sub 2}O lines and find a nuclear dust temperature of ∼40 K. IRAS 13120–5453 has a lower dust temperature and Σ{sub IR} than is inferred for the systems termed “compact obscured nuclei (CONs)” (such as Arp 220 and Mrk 231). If IRAS 13120–5453 has undergone a CON phase, we are likely witnessing it at a time when the feedback has already inflated the nuclear ISM and diluted star formation in the starburst/active galactic nucleus core.« less

Changes in the structure and ultrastructure of the intestine of Spadella cephaloptera (Chaetognatha) during feeding and starvation experiments.

PubMed

Perez; Casanova; Mazza

2000-10-05

Ultrastructural changes in the intestinal epithelium of fed and starved specimens of Spadella cephaloptera are described. Animals were maintained in a circulating natural sea water system and fed with Artemia salina nauplii. After a period of acclimation, they were individually isolated, deprived of food for 24 h and submitted to controlled feeding experiments. The absorption develop in the intestinal absorptive cells (A-cells) 5 min after the ingestion of prey and consist in the formation of endocytotic vesicles and endosome-like vacuoles. During the following steps up to 10 h, a second type of digestive vacuole containing electron-dense material, and probably corresponding to a lysosome-like compartment, appears. Throughout this time, the vacuoles progressively arrange in columns, the youngest at the top and the oldest at the bottom of the A-cells. In addition, large lipid inclusions appear in the apical cytoplasm. The ultrastructural changes of the intestinal secretory cells (S-cells) is less marked, but the number of granules largely diminishes during the first 30 min after the ingestion of prey. In starved specimens, major changes in A-cells occur between the sixth and tenth day of starvation and consist in the increase of endosome-like vacuoles. Lysosome-like vacuoles containing dense material are not observed. At the same time, necrosis features are evident in S-cells. After 30 days of starvation, necrosis features are observed in the totality of the intestinal epithelium and the specimens die few days later.

Revealing the cluster of slow transients behind a large slow slip event.

PubMed

Frank, William B; Rousset, Baptiste; Lasserre, Cécile; Campillo, Michel

2018-05-01

Capable of reaching similar magnitudes to large megathrust earthquakes [ M w (moment magnitude) > 7], slow slip events play a major role in accommodating tectonic motion on plate boundaries through predominantly aseismic rupture. We demonstrate here that large slow slip events are a cluster of short-duration slow transients. Using a dense catalog of low-frequency earthquakes as a guide, we investigate the M w 7.5 slow slip event that occurred in 2006 along the subduction interface 40 km beneath Guerrero, Mexico. We show that while the long-period surface displacement, as recorded by Global Positioning System, suggests a 6-month duration, the motion in the direction of tectonic release only sporadically occurs over 55 days, and its surface signature is attenuated by rapid relocking of the plate interface. Our proposed description of slow slip as a cluster of slow transients forces us to re-evaluate our understanding of the physics and scaling of slow earthquakes.

Surface deformations as indicators of deep ebullition fluxes in a large northern peatland

USGS Publications Warehouse

Glaser, P.H.; Chanton, J.P.; Morin, P.; Rosenberry, D.O.; Siegel, D.I.; Ruud, O.; Chasar, L.I.; Reeve, A.S.

2004-01-01

Peatlands deform elastically during precipitation cycles by small (??3 cm) oscillations in surface elevation. In contrast, we used a Global Positioning System network to measure larger oscillations that exceeded 20 cm over periods of 4-12 hours during two seasonal droughts at a bog and fen site in northern Minnesota. The second summer drought also triggered 19 depressuring cycles in an overpressured stratum under the bog site. The synchronicity between the largest surface deformations and the depressuring cycles indicates that both phenomena are produced by the episodic release of large volumes of gas from deep semi-elastic compartments confined by dense wood layers. We calculate that the three largest surface deformations were associated with the release of 136 g CH4 m-2, which exceeds by an order of magnitude the annual average chamber fluxes measured at this site. Ebullition of gas from the deep peat may therefore be a large and previously unrecognized source of radiocarbon depleted methane emissions from northern peatlands. Copyright 2004 by the American Geophysical Union.

Athena: Advanced air launched space booster

NASA Astrophysics Data System (ADS)

Booker, Corey G.; Ziemer, John; Plonka, John; Henderson, Scott; Copioli, Paul; Reese, Charles; Ullman, Christopher; Frank, Jeremy; Breslauer, Alan; Patonis, Hristos

1994-06-01

The infrastructure for routine, reliable, and inexpensive access of space is a goal that has been actively pursued over the past 50 years, but has yet not been realized. Current launch systems utilize ground launching facilities which require the booster vehicle to plow up through the dense lower atmosphere before reaching space. An air launched system on the other hand has the advantage of being launched from a carrier aircraft above this dense portion of the atmosphere and hence can be smaller and lighter compared to its ground based counterpart. The goal of last year's Aerospace Engineering Course 483 (AE 483) was to design a 227,272 kg (500,000 lb.) air launched space booster which would beat the customer's launch cost on existing launch vehicles by at least 50 percent. While the cost analysis conducted by the class showed that this goal could be met, the cost and size of the carrier aircraft make it appear dubious that any private company would be willing to invest in such a project. To avoid this potential pitfall, this year's AE 483 class was to design as large an air launched space booster as possible which can be launched from an existing or modification to an existing aircraft. An initial estimate of the weight of the booster is 136,363 kg (300,000 lb.) to 159,091 kg (350,000 lb.).

The X-ray Lightcurve of Eta Carinae, 1996-2014

NASA Astrophysics Data System (ADS)

Corcoran, Michael F.; Hamaguchi, Kenji; Liburd, Jamar; Gull, Theodore R.; Madura, Thomas; Teodoro, Mairan; Moffat, Anthony F. J.; Richardson, Noel; Russell, Christopher Michael Post; Pollock, A.; Owocki, Stanley P.

2015-01-01

Eta Carinae is the nearest example of a supermassive, superluminous, unstable star. Mass loss from the system is important in shaping its circumstellar medium and in determining the ultimate fate of the star. Eta Car loses mass via a dense, slow stellar wind and possesses one of the largest mass loss rates known. It is prone to episodes of extreme mass ejection via eruptions from some as-yet unspecified cause; the best examples of this are the large-scale eruptions which occurred in the mid-19th century, and then again about 50 years later. Eta Car is a colliding wind binary in which strong variations in X-ray emission and in other wavebands are driven by the violent collision of the wind of Eta Car and the fast, less dense wind of an otherwise hidden companion star. X-ray variations are the simplest diagnostic we have to study the wind-wind collision and allow us to measure the state of the stellar mass loss from both stars. We present the X-ray lightcurve over the last 20 years from monitoring observations with the Rossi X-ray Timing Explorer and the X-ray Telescope on the Swift satellite, and compare and contrast the behavior of the X-ray emission from the system over that timespan, including surprising variations during the 2014 X-ray minimum.

Athena: Advanced air launched space booster

NASA Technical Reports Server (NTRS)

Booker, Corey G.; Ziemer, John; Plonka, John; Henderson, Scott; Copioli, Paul; Reese, Charles; Ullman, Christopher; Frank, Jeremy; Breslauer, Alan; Patonis, Hristos

1994-01-01

The infrastructure for routine, reliable, and inexpensive access of space is a goal that has been actively pursued over the past 50 years, but has yet not been realized. Current launch systems utilize ground launching facilities which require the booster vehicle to plow up through the dense lower atmosphere before reaching space. An air launched system on the other hand has the advantage of being launched from a carrier aircraft above this dense portion of the atmosphere and hence can be smaller and lighter compared to its ground based counterpart. The goal of last year's Aerospace Engineering Course 483 (AE 483) was to design a 227,272 kg (500,000 lb.) air launched space booster which would beat the customer's launch cost on existing launch vehicles by at least 50 percent. While the cost analysis conducted by the class showed that this goal could be met, the cost and size of the carrier aircraft make it appear dubious that any private company would be willing to invest in such a project. To avoid this potential pitfall, this year's AE 483 class was to design as large an air launched space booster as possible which can be launched from an existing or modification to an existing aircraft. An initial estimate of the weight of the booster is 136,363 kg (300,000 lb.) to 159,091 kg (350,000 lb.).

Magnus integrators on multicore CPUs and GPUs

NASA Astrophysics Data System (ADS)

Auer, N.; Einkemmer, L.; Kandolf, P.; Ostermann, A.

2018-07-01

In the present paper we consider numerical methods to solve the discrete Schrödinger equation with a time dependent Hamiltonian (motivated by problems encountered in the study of spin systems). We will consider both short-range interactions, which lead to evolution equations involving sparse matrices, and long-range interactions, which lead to dense matrices. Both of these settings show very different computational characteristics. We use Magnus integrators for time integration and employ a framework based on Leja interpolation to compute the resulting action of the matrix exponential. We consider both traditional Magnus integrators (which are extensively used for these types of problems in the literature) as well as the recently developed commutator-free Magnus integrators and implement them on modern CPU and GPU (graphics processing unit) based systems. We find that GPUs can yield a significant speed-up (up to a factor of 10 in the dense case) for these types of problems. In the sparse case GPUs are only advantageous for large problem sizes and the achieved speed-ups are more modest. In most cases the commutator-free variant is superior but especially on the GPU this advantage is rather small. In fact, none of the advantage of commutator-free methods on GPUs (and on multi-core CPUs) is due to the elimination of commutators. This has important consequences for the design of more efficient numerical methods.

Inhomogeneous quasistationary state of dense fluids of inelastic hard spheres

NASA Astrophysics Data System (ADS)

Fouxon, Itzhak

2014-05-01

We study closed dense collections of freely cooling hard spheres that collide inelastically with constant coefficient of normal restitution. We find inhomogeneous states (ISs) where the density profile is spatially nonuniform but constant in time. The states are exact solutions of nonlinear partial differential equations that describe the coupled distributions of density and temperature valid when inelastic losses of energy per collision are small. The derivation is performed without modeling the equations' coefficients that are unknown in the dense limit (such as the equation of state) using only their scaling form specific for hard spheres. Thus the IS is the exact state of this dense many-body system. It captures a fundamental property of inelastic collections of particles: the possibility of preserving nonuniform temperature via the interplay of inelastic cooling and heat conduction that generalizes previous results. We perform numerical simulations to demonstrate that arbitrary initial state evolves to the IS in the limit of long times where the container has the geometry of the channel. The evolution is like a gas-liquid transition. The liquid condenses in a vanishing part of the total volume but takes most of the mass of the system. However, the gaseous phase, which mass grows only logarithmically with the system size, is relevant because its fast particles carry most of the energy of the system. Remarkably, the system self-organizes to dissipate no energy: The inelastic decay of energy is a power law [1+t/tc]-2, where tc diverges in the thermodynamic limit. This is reinforced by observing that for supercritical systems the IS coincide in most of the space with the steady states of granular systems heated at one of the walls. We discuss the relation of our results to the recently proposed finite-time singularity in other container's geometries.

Point Source X-Ray Lithography System for Sub-0.15 Micron Design Rules

DTIC Science & Technology

1998-05-22

consist of a SAL developed stepper, an SRL developed Dense Plasma Focus , (DPF), X-Ray source, and a CXrL developed beam line. The system will be...existing machine that used spark gap switching, SRL has developed an all solid state driver and improved head electrode assembly for their dense plasma ... focus X-Ray source. Likewise, SAL has used their existing Model 4 stepper installed at CXrL as a design starting point, and has developed an advanced

Effect of temperature on the shape of spatial quasi-periodic oscillations of the refractive index of alkali atoms in an optically dense medium with a closed excitation contour of Δ type

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barantsev, K A; Litvinov, A N

2014-10-31

A theory of a closed excitation contour (Δ system) of a three-level atom in an optically dense medium is constructed with allowance for temperature. The spatial quasi-periodic oscillations of the refractive index in the system under study are shown to damp with increasing temperature. The range of temperatures at which these oscillations are most pronounced is found. (quantum optics)

Can GRACE detect winter snows in Japan?

NASA Astrophysics Data System (ADS)

Heki, Kosuke

2010-05-01

Current spatial resolution of the GRACE (Gravity Recovery and Climate Experiment) satellites is 300-400 km, and so its hydrological applications have been limited to continents and large islands. The Japanese Islands have width slightly smaller than this spatial resolution, but are known to show large amplitude seasonal changes in surface masses due mainly to winter snow. Such loads are responsible for seasonal crustal deformation observed with GEONET, a dense array of GPS (Global Positioning System) receivers in Japan (Heki, 2001). There is also a dense network of surface meteorological sensors for, e.g. snow depths, atmospheric pressures, etc. Heki (2004) showed that combined effects of surface loads, i.e. snow (predominant), atmosphere, soil moisture, dam impoundment, can explain seasonal crustal deformation observed by GPS to a large extent. The total weight of the winter snow in the Japanese Islands in its peak season may reach ~50 Gt. This is comparable to the annual loss of mountain glaciers in the Asian high mountains (Matsuo & Heki, 2010), and is above the detection level of GRACE. In this study, I use GRACE Level-2 Release-4 data from CSR, Univ. Texas, up to 2009 November, and evaluated seasonal changes in surface loads in and around the Japanese Islands. After applying a 350 km Gaussian filter and a de-striping filter, the peak-to-peak change of the water depth becomes ~4 cm in northern Japan. The maximum value is achieved in February-March. The region of large winter load spans from Hokkaido, Japan, to northeastern Honshu, which roughly coincides with the region of deep snow in Japan. Next I compiled snow depth data from surface meteorological observations, and converted them to loads using time-dependent snow density due to compaction. By applying the same spatial filter as the GRACE data, its spatial pattern becomes similar to the GRACE results. The present study suggests that GRACE is capable of detecting seasonal mass changes in an island arc not wider than a few hundreds of kilometers. References: Heki, K., Seasonal modulation of interseismic strain buildup in Northeastern Japan driven by snow loads, Science, 293, 89-92, 2001. Heki, K., Dense GPS array as a new sensor of seasonal changes of surface loads, AGU Monograph, 150, 177-196, 2004. Matsuo, K. and K. Heki, Time-variable ice loss in Asian high mountains from satellite gravimetry, Earth Planet. Sci. Lett., doi:10.1016/j.epsl.2009.11.053, 2010.

GigaGauss solenoidal magnetic field inside bubbles excited in under-dense plasma

PubMed Central

Lécz, Zs.; Konoplev, I. V.; Seryi, A.; Andreev, A.

2016-01-01

This paper proposes a novel and effective method for generating GigaGauss level, solenoidal quasi-static magnetic fields in under-dense plasma using screw-shaped high intensity laser pulses. This method produces large solenoidal fields that move with the driving laser pulse and are collinear with the accelerated electrons. This is in contrast with already known techniques which rely on interactions with over-dense or solid targets and generates radial or toroidal magnetic field localized at the stationary target. The solenoidal field is quasi-stationary in the reference frame of the laser pulse and can be used for guiding electron beams. It can also provide synchrotron radiation beam emittance cooling for laser-plasma accelerated electron and positron beams, opening up novel opportunities for designs of the light sources, free electron lasers, and high energy colliders based on laser plasma acceleration. PMID:27796327

GigaGauss solenoidal magnetic field inside bubbles excited in under-dense plasma

NASA Astrophysics Data System (ADS)

Lécz, Zs.; Konoplev, I. V.; Seryi, A.; Andreev, A.

2016-10-01

This paper proposes a novel and effective method for generating GigaGauss level, solenoidal quasi-static magnetic fields in under-dense plasma using screw-shaped high intensity laser pulses. This method produces large solenoidal fields that move with the driving laser pulse and are collinear with the accelerated electrons. This is in contrast with already known techniques which rely on interactions with over-dense or solid targets and generates radial or toroidal magnetic field localized at the stationary target. The solenoidal field is quasi-stationary in the reference frame of the laser pulse and can be used for guiding electron beams. It can also provide synchrotron radiation beam emittance cooling for laser-plasma accelerated electron and positron beams, opening up novel opportunities for designs of the light sources, free electron lasers, and high energy colliders based on laser plasma acceleration.

What Determines Star Formation Rates?

NASA Astrophysics Data System (ADS)

Evans, Neal John

2017-06-01

The relations between star formation and gas have received renewed attention. We combine studies on scales ranging from local (within 0.5 kpc) to distant galaxies to assess what factors contribute to star formation. These include studies of star forming regions in the Milky Way, the LMC, nearby galaxies with spatially resolved star formation, and integrated galaxy studies. We test whether total molecular gas or dense gas provides the best predictor of star formation rate. The star formation ``efficiency," defined as star formation rate divided by mass, spreads over a large range when the mass refers to molecular gas; the standard deviation of the log of the efficiency decreases by a factor of three when the mass of relatively dense molecular gas is used rather than the mass of all the molecular gas. We suggest ways to further develop the concept of "dense gas" to incorporate other factors, such as turbulence.

Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs

DOE PAGES

Booth, N.; Robinson, A. P. L.; Hakel, P.; ...

2015-11-06

Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. Furthermore, themore » inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs.« less

The Green Bank Ammonia Survey of the Gould Belt

NASA Astrophysics Data System (ADS)

Friesen, Rachel; Pineda, Jaime; GAS Team

2018-01-01

The past several years have seen a tremendous advancement in our ability to characterize the structure of nearby molecular clouds traced by large-scale continuum surveys. Critical, comparable data on the dense gas kinematics and temperatures are needed to understand the history and future fate of star-forming material. Filling this gap is the Green Bank Ammonia Survey (GAS), an ambitious legacy survey for the Green Bank Telescope to observe key molecular tracers of dense gas within all Gould Belt clouds visible from the northern hemisphere. I will present the latest science from GAS, whose goals are to 1) evaluate the stability of dense gas structures as a function of scale, 2) track the dissipation of turbulence and evolution of angular momentum in filaments and cores, and 3) quantitatively test predictions of models of core and filament formation via mass flows and accretion.

The effects of time on the capacity of pipe piles in dense marine sand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, F.C.; Jardine, R.J.; Brucy, F.

Investigations into pile behavior in dense marine sand have been performed by IFP and IC at Dunkirk, North France. In the most recent series of tests, strain-gauged, open-ended pipe piles, driven and statically load tested in 1989, were retested in 1994. Surprisingly large increases in shaft capacity were measured. The possible causes are evaluated in relation to previous case histories, laboratory soil tests, pile corrosion and new effective stress analyses developed using smaller, more intensively instrumented piles. The shaft capacities predicted by existing design methods are also assessed. 51 refs., 12 figs., 4 tabs.

Large-scale fabrication of vertically aligned ZnO nanowire arrays

DOEpatents

Wang, Zhong Lin; Hu, Youfan; Zhang, Yan; Xu, Chen; Zhu, Guang

2014-09-09

A generator includes a substrate, a first electrode layer, a dense plurality of vertically-aligned piezoelectric elongated nanostructures, an insulating layer and a second electrode layer. The substrate has a top surface and the first electrode layer is disposed on the top surface of the substrate. The dense plurality of vertically-aligned piezoelectric elongated nanostructures extends from the first electrode layer. Each of the nanostructures has a top end. The insulating layer is disposed on the top ends of the nanostructures. The second electrode layer is disposed on the non-conductive layer and is spaced apart from the nanostructures.

Quantum statistical mechanics of dense partially ionized hydrogen

NASA Technical Reports Server (NTRS)

Dewitt, H. E.; Rogers, F. J.

1972-01-01

The theory of dense hydrogen plasmas beginning with the two component quantum grand partition function is reviewed. It is shown that ionization equilibrium and molecular dissociation equilibrium can be treated in the same manner with proper consideration of all two-body states. A quantum perturbation expansion is used to give an accurate calculation of the equation of state of the gas for any degree of dissociation and ionization. The statistical mechanical calculation of the plasma equation of state is intended for stellar interiors. The general approach is extended to the calculation of the equation of state of the outer layers of large planets.

Planar ceramic membrane assembly and oxidation reactor system

DOEpatents

Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohm, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, deceased, Paul Nigel

2007-10-09

Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

Planar ceramic membrane assembly and oxidation reactor system

DOEpatents

Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohrn, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, Paul Nigel

2009-04-07

Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

Molecular Composition and Chemistry of Isolated Dense Cores

NASA Astrophysics Data System (ADS)

Cook, Amanda; Boogert, A.

2009-01-01

The composition of molecular clouds and the envelopes and disks surrounding low mass protostars within them is still poorly known. There is little doubt that a large fraction of the molecules is frozen on grains, but the abundance of several crucial species (e.g. ammonia, methanol, ions) in the ices is still uncertain. In addition, prominent spectral features discovered decades ago are still not securely identified (e.g. the 6.85-micron absorption band). Gas phase and grain surface chemistry play pivotal roles in molecule formation, but numerous other processes could have significant impacts as well: shocks, thermal heating, irradiation of ices by ultraviolet photons and cosmic rays. Complex species could be formed this way, profoundly influencing cloud, disk and planetary/cometary chemistry. We have obtained Spitzer/IRS spectra of an unprecedented sample of sight-lines tracing 25 dense isolated cores. These cores physically differ from the large, cluster-forming molecular clouds (e.g. Ophiuchus, Perseus) that are commonly studied: they are less turbulent, colder, less dense, and likely longer lived. These IRS spectra of isolated cores thus provide unique information on ice formation and destruction mechanisms. Toward the same cores, we observed 33 highly extincted background stars as well, tracing the quiescent cloud medium against which the ices around protostars can be contrasted.

Multi-cathode unbalanced magnetron sputtering systems

NASA Technical Reports Server (NTRS)

Sproul, William D.

1991-01-01

Ion bombardment of a growing film during deposition is necessary in many instances to ensure a fully dense coating, particularly for hard coatings. Until the recent advent of unbalanced magnetron (UBM) cathodes, reactive sputtering had not been able to achieve the same degree of ion bombardment as other physical vapor deposition processes. The amount of ion bombardment of the substrate depends on the plasma density at the substrate, and in a UBM system the amount of bombardment will depend on the degree of unbalance of the cathode. In multi-cathode systems, the magnetic fields between the cathodes must be linked to confine the fast electrons that collide with the gas atoms. Any break in this linkage results in electrons being lost and a low plasma density. Modeling of the magnetic fields in a UBM cathode using a finite element analysis program has provided great insight into the interaction between the magnetic fields in multi-cathode systems. Large multi-cathode systems will require very strong magnets or many cathodes in order to maintain the magnetic field strength needed to achieve a high plasma density. Electromagnets offer the possibility of independent control of the plasma density. Such a system would be a large-scale version of an ion beam enhanced deposition (IBED) system, but, for the UBM system where the plasma would completely surround the substrate, the acronym IBED might now stand for Ion Blanket Enhanced Deposition.

Concentrations of hormones, pharmaceuticals and other micropollutants in groundwater affected by septic systems in New England and New York.

PubMed

Phillips, P J; Schubert, C; Argue, D; Fisher, I; Furlong, E T; Foreman, W; Gray, J; Chalmers, A

2015-04-15

Septic-system discharges can be an important source of micropollutants (including pharmaceuticals and endocrine active compounds) to adjacent groundwater and surface water systems. Groundwater samples were collected from well networks tapping glacial till in New England (NE) and sandy surficial aquifer New York (NY) during one sampling round in 2011. The NE network assesses the effect of a single large septic system that receives discharge from an extended health care facility for the elderly. The NY network assesses the effect of many small septic systems used seasonally on a densely populated portion of Fire Island. The data collected from these two networks indicate that hydrogeologic and demographic factors affect micropollutant concentrations in these systems. The highest micropollutant concentrations from the NE network were present in samples collected from below the leach beds and in a well downgradient of the leach beds. Total concentrations for personal care/domestic use compounds, pharmaceutical compounds and plasticizer compounds generally ranged from 1 to over 20 μg/L in the NE network samples. High tris(2-butoxyethyl phosphate) plasticizer concentrations in wells beneath and downgradient of the leach beds (>20 μg/L) may reflect the presence of this compound in cleaning agents at the extended health-care facility. The highest micropollutant concentrations for the NY network were present in the shoreline wells and reflect groundwater that is most affected by septic system discharges. One of the shoreline wells had personal care/domestic use, pharmaceutical, and plasticizer concentrations ranging from 0.4 to 5.7 μg/L. Estradiol equivalency quotient concentrations were also highest in a shoreline well sample (3.1 ng/L). Most micropollutant concentrations increase with increasing specific conductance and total nitrogen concentrations for shoreline well samples. These findings suggest that septic systems serving institutional settings and densely populated areas in coastal settings may be locally important sources of micropollutants to adjacent aquifer and marine systems. Published by Elsevier B.V.

Methane Hydrate in Confined Spaces: An Alternative Storage System.

PubMed

Borchardt, Lars; Casco, Mirian Elizabeth; Silvestre-Albero, Joaquin

2018-06-05

Methane hydrate inheres the great potential to be a nature-inspired alternative for chemical energy storage, as it allows to store large amounts of methane in a dense solid phase. The embedment of methane hydrate in the confined environment of porous materials can be capitalized for potential applications as its physicochemical properties, such as the formation kinetics or pressure and temperature stability, are significantly changed compared to the bulk system. We review this topic from a materials scientific perspective by considering porous carbons, silica, clays, zeolites, and polymers as host structures for methane hydrate formation. We discuss the contribution of advanced characterization techniques and theoretical simulations towards the elucidation of the methane hydrate formation and dissociation process within the confined space. We outline the scientific challenges this system is currently facing and look on possible future applications for this technology. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantum Control of Open Systems and Dense Atomic Ensembles

NASA Astrophysics Data System (ADS)

DiLoreto, Christopher

Controlling the dynamics of open quantum systems; i.e. quantum systems that decohere because of interactions with the environment, is an active area of research with many applications in quantum optics and quantum computation. My thesis expands the scope of this inquiry by seeking to control open systems in proximity to an additional system. The latter could be a classical system such as metal nanoparticles, or a quantum system such as a cluster of similar atoms. By modelling the interactions between the systems, we are able to expand the accessible state space of the quantum system in question. For a single, three-level quantum system, I examine isolated systems that have only normal spontaneous emission. I then show that intensity-intensity correlation spectra, which depend directly on the density matrix of the system, can be used detect whether transitions share a common energy level. This detection is possible due to the presence of quantum interference effects between two transitions if they are connected. This effect allows one to asses energy level structure diagrams in complex atoms/molecules. By placing an open quantum system near a nanoparticle dimer, I show that the spontaneous emission rate of the system can be changed "on demand" by changing the polarization of an incident, driving field. In a three-level, Lambda system, this allows a qubit to both retain high qubit fidelity when it is operating, and to be rapidly initialized to a pure state once it is rendered unusable by decoherence. This type of behaviour is not possible in a single open quantum system; therefore adding a classical system nearby extends the overall control space of the quantum system. An open quantum system near identical neighbours in a dense ensemble is another example of how the accessible state space can be expanded. I show that a dense ensemble of atoms rapidly becomes disordered with states that are not directly excited by an incident field becoming significantly populated. This effect motivates the need for using multi-directional basis sets in theoretical analysis of dense quantum systems. My results demonstrate the shortcomings of short-pulse techniques used in many recent studies. Based on my numerical studies, I hypothesize that the dense ensemble can be modelled by an effective single quantum system that has a decoherence rate that changes over time. My effective single particle model provides a way in which computational time can be reduced, and also a model in which the underlying physical processes involved in the system's evolution are much easier to understand. I then use this model to provide an elegant theoretical explanation for an unusual experimental result called "transverse optical magnetism''. My effective single particle model's predictions match very well with experimental data.

Quantum Linear System Algorithm for Dense Matrices

NASA Astrophysics Data System (ADS)

Wossnig, Leonard; Zhao, Zhikuan; Prakash, Anupam

2018-02-01

Solving linear systems of equations is a frequently encountered problem in machine learning and optimization. Given a matrix A and a vector b the task is to find the vector x such that A x =b . We describe a quantum algorithm that achieves a sparsity-independent runtime scaling of O (κ2√{n }polylog(n )/ɛ ) for an n ×n dimensional A with bounded spectral norm, where κ denotes the condition number of A , and ɛ is the desired precision parameter. This amounts to a polynomial improvement over known quantum linear system algorithms when applied to dense matrices, and poses a new state of the art for solving dense linear systems on a quantum computer. Furthermore, an exponential improvement is achievable if the rank of A is polylogarithmic in the matrix dimension. Our algorithm is built upon a singular value estimation subroutine, which makes use of a memory architecture that allows for efficient preparation of quantum states that correspond to the rows of A and the vector of Euclidean norms of the rows of A .

Propagation of monochromatic light in a hot and dense medium

NASA Astrophysics Data System (ADS)

Masood, Samina S.

2017-12-01

Photons, as quanta of electromagnetic fields, determine the electromagnetic properties of an extremely hot and dense medium. Considering the properties of the photons in the interacting medium of charged particles, we explicitly calculate the electromagnetic properties such as the electric permittivity, magnetic permeability, refractive index and the propagation speed of electromagnetic signals in an extremely hot and dense background. Photons acquire a dynamically generated mass in such a medium. The screening mass of the photon, the Debye shielding length and the plasma frequency are calculated as functions of the statistical parameters of the medium. We study the properties of the propagating particles in astrophysical systems of distinct statistical conditions. The modifications in the properties of the medium lead to the equation of state of the system. We mainly calculate all these parameters for extremely high temperatures of the early universe.

Warm Dense Matter: Another Application for Pulsed Power Hydrodynamics

DTIC Science & Technology

2009-06-01

Pulsed power hydrodynamic techniques, such as large convergence liner compression of a large volume, modest density, low temperature plasma to...controlled than are similar high explosively powered hydrodynamic experiments. While the precision and controllability of gas- gun experiments is...well established, pulsed power techniques using imploding liner offer access to convergent conditions, difficult to obtain with guns – and essential

Process for fabrication of large titanium diboride ceramic bodies

DOEpatents

Moorhead, Arthur J.; Bomar, E. S.; Becher, Paul F.

1989-01-01

A process for manufacturing large, fully dense, high purity TiB.sub.2 articles by pressing powders with a sintering aid at relatively low temperatures to reduce grain growth. The process requires stringent temperature and pressure applications in the hot-pressing step to ensure maximum removal of sintering aid and to avoid damage to the fabricated article or the die.

Detuning-induced stimulated Raman adiabatic passage in dense two-level systems

NASA Astrophysics Data System (ADS)

Deng, Li; Lin, Gongwei; Niu, Yueping; Gong, Shangqing

2018-05-01

We investigate the coherence generation in dense two-level systems under detuning-induced stimulated Raman adiabatic passage (D-STIRAP). In the dense two-level system, the near dipole-dipole (NDD) interaction should be taken into consideration. With the increase in the strength of the NDD interaction, it is found that a switchlike transition of the generated coherence from maximum value to zero appears. Meanwhile, the adiabatic condition of the D-STIRAP is destroyed in the presence of the NDD interaction. In order to avoid the sudden decrease in the generated coherence and maintain the maximum value, we can use stronger detuning pulse or pump pulse, between which increasing the intensity of the detuning pulse is of more efficiency. Except for taking advantage of such maximum coherence in the high density case into areas like enhancing the four-wave mixing process, we also point out that the phenomenon of the coherence transition can be applied as an optical switch.

Gas purification in the dense phase at the CATS terminal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Openshaw, P.J.; Carnell, P.J.H.; Rhodes, E.F.

The purification and transportation of natural gas at very high pressures can help to minimize the capital cost of pipelines and processing equipment. However, complex mixtures of hydrocarbons undergo unusual phase changes, such as retrograde condensation, as the temperature and pressure are altered. The Central Area Transmission System (CATS) is a joint venture of Amoci, BG, Amerada Hess, Phillips, Agip and Fina operated by Amoco on behalf of the owners. The design of the CATS terminal has provided an interesting processing challenge. The terminal receives a total of 1.6 Bscf/d of rich gas from a number of offshore fields. Allmore » are relatively sweet but the small amounts of H{sub 2}S and Hg are removed. Fixed bed technology was selected as the most economic purification process, while minimizing hydrocarbon loss and operator involvement. Conventionally, the raw gas would be split into the different hydrocarbon fractions and each would be processed separately. This would require the installation of a large number of reactors. A more elegant solution is to treat the gas on arrival at the terminal in the dense phase. This option raised questions around whether a fixed bed would be prone to fouling, could the pressure drop be kept low enough to avoid phase separation and would inadvertent wetting by condensation cause problems. Details are given of the test work carried out to prove the viability of using fixed bed technology for dense phase gas processing, the eventual design adopted and the performance over the first year of service.« less

Elaiophores in Gomesa bifolia (Sims) M.W. Chase & N.H. Williams (Oncidiinae: Cymbidieae: Orchidaceae): structure and oil secretion

PubMed Central

Aliscioni, Sandra S.; Torretta, Juan P.; Bello, Mariano E.; Galati, Beatriz G.

2009-01-01

Background and Aims Oils are an unusual floral reward in Orchidaceae, being produced by specialized glands called elaiophores. Such glands have been described in subtribe Oncidiinae for a few species. The aims of the present study were to identify the presence of elaiophores in Gomesa bifolia, to study their structure and to understand how the oil is secreted. Additionally, elaiophores of G. bifolia were compared with those of related taxa within the Oncidiinae. Methods Elaiophores were identified using Sudan III. Their structure was examined by using light, scanning electron and transmission electron microscopy. Key Results Secretion of oils was from the tips of callus protrusions. The secretory cells each had a large, centrally located nucleus, highly dense cytoplasm, abundant plastids containing lipid globules associated with starch grains, numerous mitochondria, an extensive system of rough and smooth endoplasmatic reticulum, and electron-dense dictyosomes. The outer tangential walls were thick, with a loose cellulose matrix and a few, sparsely distributed inconspicuous cavities. Electron-dense structures were observed in the cell wall and formed a lipid layer that covered the cuticle of the epidermal cells. The cuticle as viewed under the scanning electron microscope was irregularly rugose. Conclusions The elaiophores of G. bifolia are of the epithelial type. The general structure of the secretory cells resembles that described for other species of Oncidiinae, but some unique features were encountered for this species. The oil appears to pass through the outer tangential wall and the cuticle, covering the latter without forming cuticular blisters. PMID:19692391

Decentralized System Identification Using Stochastic Subspace Identification for Wireless Sensor Networks

PubMed Central

Cho, Soojin; Park, Jong-Woong; Sim, Sung-Han

2015-01-01

Wireless sensor networks (WSNs) facilitate a new paradigm to structural identification and monitoring for civil infrastructure. Conventional structural monitoring systems based on wired sensors and centralized data acquisition systems are costly for installation as well as maintenance. WSNs have emerged as a technology that can overcome such difficulties, making deployment of a dense array of sensors on large civil structures both feasible and economical. However, as opposed to wired sensor networks in which centralized data acquisition and processing is common practice, WSNs require decentralized computing algorithms to reduce data transmission due to the limitation associated with wireless communication. In this paper, the stochastic subspace identification (SSI) technique is selected for system identification, and SSI-based decentralized system identification (SDSI) is proposed to be implemented in a WSN composed of Imote2 wireless sensors that measure acceleration. The SDSI is tightly scheduled in the hierarchical WSN, and its performance is experimentally verified in a laboratory test using a 5-story shear building model. PMID:25856325

Flea (Siphonaptera) species richness in the Great Basin Desert and island biogeography theory.

PubMed

Bossard, Robert L

2014-06-01

Numbers of flea (Siphonaptera) species (flea species richness) on individual mammals should be higher on large mammals, mammals with dense populations, and mammals with large geographic ranges, if mammals are islands for fleas. I tested the first two predictions with regressions of H. J. Egoscue's trapping data on flea species richness collected from individual mammals against mammal size and population density from the literature. Mammal size and population density did not correlate with flea species richness. Mammal geographic range did, in earlier studies. The intermediate-sized (31 g), moderately dense (0.004 individuals/m(2)) Peromyscus truei (Shufeldt) had the highest richness with eight flea species on one individual. Overall, island biogeography theory does not describe the distribution of flea species on mammals in the Great Basin Desert, based on H. J. Egoscue's collections. Alternatively, epidemiological or metapopulation theories may explain flea species richness. © 2014 The Society for Vector Ecology.

Optimal degrees of synaptic connectivity

PubMed Central

Litwin-Kumar, Ashok; Harris, Kameron Decker; Axel, Richard; Sompolinsky, Haim; Abbott, L. F.

2017-01-01

Summary Synaptic connectivity varies widely across neuronal types. Cerebellar granule cells receive five orders of magnitude fewer inputs than the Purkinje cells they innervate, and cerebellum-like circuits including the insect mushroom body also exhibit large divergences in connectivity. In contrast, the number of inputs per neuron in cerebral cortex is more uniform and large. We investigate how the dimension of a representation formed by a population of neurons depends on how many inputs they each receive and what this implies for learning associations. Our theory predicts that the dimensions of the cerebellar granule-cell and Drosophila Kenyon-cell representations are maximized at degrees of synaptic connectivity that match those observed anatomically, showing that sparse connectivity is sometimes superior to dense connectivity. When input synapses are subject to supervised plasticity, however, dense wiring becomes advantageous, suggesting that the type of plasticity exhibited by a set of synapses is a major determinant of connection density. PMID:28215558

Change in Dense Shelf Water and Adélie Land Bottom Water Precipitated by Iceberg Calving

NASA Astrophysics Data System (ADS)

Snow, K.; Rintoul, S. R.; Sloyan, B. M.; Hogg, A. McC.

2018-03-01

Antarctic Bottom Water supplies the deep limb of the global overturning circulation and ventilates the abyssal ocean. Antarctic Bottom Water has warmed, freshened, and contracted in recent decades, but the causes remain poorly understood. We use unique multiyear observations from the continental shelf and deep ocean near the Mertz Polynya to examine the sensitivity of this bottom water formation region to changes on the continental shelf, including the calving of a large iceberg. Postcalving, the seasonal cycle of Dense Shelf Water (DSW) density almost halved in amplitude and the volume of DSW available for export reduced. In the deep ocean, the density and volume of Adélie Land Bottom Water decreased sharply after calving, while oxygen concentrations remained high, indicating continued ventilation by DSW. This natural experiment illustrates how local changes in forcing over the Antarctic continental shelf can drive large and rapid changes in the abyssal ocean.

A Brief Update on the CMZoom Survey

NASA Astrophysics Data System (ADS)

Battersby, C.; Keto, E.; Zhang, Q.; Longmore, S. N.; Kruijssen, J. M. D.; Pillai, T.; Kauffmann, J.; Walker, D.; Lu, X.; Ginsburg, A.; Bally, J.; Mills, E. A. C.; Henshaw, J.; Immer, K.; Patel, N.; Tolls, V.; Walsh, A.; Johnston, K.; Ho, L. C.

2017-01-01

The inner few hundred parsecs of the Milky Way, the Central Molecular Zone (CMZ), is our closest laboratory for understanding star formation in the extreme environments (hot, dense, turbulent gas) that once dominated the universe. We present an update on the first large-area survey to expose the sites of star formation across the CMZ at high-resolution in submillimeter wavelengths: the CMZoom survey with the Submillimeter Array (SMA). We identify the locations of dense cores and search for signatures of embedded star formation. CMZoom is a three-year survey in its final year and is mapping out the highest column density regions of the CMZ in dust continuum and a variety of spectral lines around 1.3 mm. CMZoom combines SMA compact and subcompact configurations with single-dish data from BGPS and the APEX telescope, achieving an angular resolution of about 4'' (0.2 pc) and good image fidelity up to large spatial scales.

CMZoom: The Submillimeter Array Survey of our Galaxy’s Central Molecular Zone

NASA Astrophysics Data System (ADS)

Battersby, Cara; CMZoom Team

2018-01-01

The inner few hundred parsecs of the Milky Way, the Central Molecular Zone (CMZ), is our closest laboratory for understanding star formation in the extreme environments (hot, dense, turbulent gas) that once dominated the universe. We present an update on the first large-area survey to expose the sites of star formation across the CMZ at high-resolution in submillimeter wavelengths: the CMZoom survey with the Submillimeter Array (SMA). We identify the locations of dense cores and search for signatures of embedded star formation. CMZoom is a three-year survey, completed this year, and has mapped out the highest column density regions of the CMZ in dust continuum and a variety of spectral lines around 1.3 mm. CMZoom combines SMA compact and subcompact configurations with single-dish data from BGPS and the APEX telescope, achieving an angular resolution of about 4” (0.2 pc) and good image fidelity up to large spatial scales.

From ATLASGAL to SEDIGISM: Towards a Complete 3D View of the Dense Galactic Interstellar Medium

NASA Astrophysics Data System (ADS)

Schuller, F.; Urquhart, J.; Bronfman, L.; Csengeri, T.; Bontemps, S.; Duarte-Cabral, A.; Giannetti, A.; Ginsburg, A.; Henning, T.; Immer, K.; Leurini, S.; Mattern, M.; Menten, K.; Molinari, S.; Muller, E.; Sánchez-Monge, A.; Schisano, E.; Suri, S.; Testi, L.; Wang, K.; Wyrowski, F.; Zavagno, A.

2016-09-01

The ATLASGAL survey has provided the first unbiased view of the inner Galactic Plane at sub-millimetre wavelengths. This is the largest ground-based survey of its kind to date, covering 420 square degrees at a wavelength of 870 µm. The reduced data, consisting of images and a catalogue of > 104 compact sources, are available from the ESO Science Archive Facility through the Phase 3 infrastructure. The extremely rich statistics of this survey initiated several follow-up projects, including spectroscopic observations to explore molecular complexity and high angular resolution imaging with the Atacama Large Millimeter/submillimeter Array (ALMA), aimed at resolving individual protostars. The most extensive follow-up project is SEDIGISM, a 3D mapping of the dense interstellar medium over a large fraction of the inner Galaxy. Some notable results of these surveys are highlighted.

Laser-Produced Colliding Plasmas on LaPD

NASA Astrophysics Data System (ADS)

Collette, Andrew

2005-10-01

The expansion and interaction of dense plasmas in the presence of a magnetized background plasma is important in many astrophysical processes, among them shocks which transport energy. We study the collision of two dense, laser-produced plasmas expanding perpendicular to the background magnetic field, each with an Alfv'en Mach number of approximately 0.5. The plasmas are launched off of two carbon targets, 9cm apart, by a short pulse of laser energy (Nd:YAG, 1J 8ns). Experiments are currently in progress in a small test chamber at UCLA (background plasma n 3x10^12, 3 meters long, B0<700G) and will shortly be migrated to the LaPD (LArge Plasma Device; n 3x10^12, 18 meters long, 70cm diameter, 400G

Causes of metabolic syndrome and obesity-related co-morbidities Part 1: A composite unifying theory review of human-specific co-adaptations to brain energy consumption

PubMed Central

2014-01-01

One line summary Metabolic syndrome and obesity-related co-morbidities are largely explained by co-adaptations to the energy use of the large human brain in the cortico-limbic-striatal and NRF2 systems. The medical, research and general community is unable to effect significantly decreased rates of central obesity and related type II diabetes mellitus (TIIDM), cardiovascular disease (CVD) and cancer. All conditions seem to be linked by the concept of the metabolic syndrome (MetS), but the underlying causes are not known. MetS markers may have been mistaken for causes, thus many treatments are destined to be suboptimal. The current paper aims to critique current paradigms, give explanations for their persistence, and to return to first principles in an attempt to determine and clarify likely causes of MetS and obesity related comorbidities. A wide literature has been mined, study concepts analysed and the basics of human evolution and new biochemistry reviewed. A plausible, multifaceted composite unifying theory is formulated. The basis of the theory is that the proportionately large, energy-demanding human brain may have driven co-adaptive mechanisms to provide, or conserve, energy for the brain. A ‘dual system’ is proposed. 1) The enlarged, complex cortico-limbic-striatal system increases dietary energy by developing strong neural self-reward/motivation pathways for the acquisition of energy dense food, and (2) the nuclear factor-erythroid 2-related factor 2 (NRF2) cellular protection system amplifies antioxidant, antitoxicant and repair activity by employing plant chemicals, becoming highly energy efficient in humans. The still-evolving, complex human cortico-limbic-striatal system generates strong behavioural drives for energy dense food procurement, including motivating agricultural technologies and social system development. Addiction to such foods, leading to neglect of nutritious but less appetizing ‘common or garden’ food, appears to have occurred. Insufficient consumption of food micronutrients prevents optimal human NRF2 function. Inefficient oxidation of excess energy forces central and non-adipose cells to store excess toxic lipid. Oxidative stress and metabolic inflammation, or metaflammation, allow susceptibility to infectious, degenerative atherosclerotic cardiovascular, autoimmune, neurodegenerative and dysplastic diseases. Other relevant human-specific co-adaptations are examined, and encompass the unusual ability to store fat, certain vitamin pathways, the generalised but flexible intestine and microbiota, and slow development and longevity. This theory has significant past and future corollaries, which are explored in a separate article by McGill, A-T, in Archives of Public Health, 72: 31. PMID:25708524

Cost-effectiveness analysis of dose-dense versus standard intravenous chemotherapy for ovarian cancer: An economic analysis of results from the Gynecologic Oncology Group protocol 262 randomized controlled trial.

PubMed

Seagle, Brandon-Luke L; Shahabi, Shohreh

2017-04-01

To determine the cost-effectiveness of dose-dense versus standard intravenous adjuvant chemotherapy for ovarian cancer using results from the no-bevacizumab cohort of the Gynecologic Oncology Group protocol 262 (GOG-262) randomized controlled trial, which reported a smaller absolute progression-free survival (PFS) benefit than the prior Japanese trial. A three-state Markov decision model from a healthcare system perspective with a 21day cycle length and 28month time-horizon was used to calculate incremental cost-effectiveness ratio (ICER) values per progression-free life-year saved (PFLYS) using results from GOG-262. Costs of chemotherapy, complications, and surveillance were from Medicare or institutional data. PFS, discontinuation, and complication rates were from GOG-262. Time-dependent transition probabilities and within-cycle corrections were used. One-way and probabilistic sensitivity analyses were performed. The model produces standard and dose-dense cohorts with 84.3% and 68.3% progression event proportions at 28months, matching GOG-262 rates at the trial's median follow-up. With a median PFS of 10.3months after standard chemotherapy and a hazard ratio for progression of 0.62 after dose-dense therapy, the ICER for dose-dense chemotherapy is $8074.25 (95% confidence interval: $7615.97-$10,207.16) per PFLYS. ICER estimates are sensitive only to the hazard ratio estimate but do not exceed $100,000 per PFLYS. 99.8% of ICER estimates met a more stringent willingness-to-pay of $50,000 per PFLYS. The willingness-to-pay value at which there is a 90% probability of dose-dense treatment being cost-effective is $12,000 per PFLYS. Dose-dense adjuvant chemotherapy is robustly cost-effective for advanced ovarian cancer from a healthcare system perspective based on results from GOG-262. Copyright © 2017 Elsevier Inc. All rights reserved.

Influence of Agropastoral System Components on Mountain Grassland Vulnerability Estimated by Connectivity Loss

PubMed Central

Fillat, Federico; Pérez-Cabello, Fernando; Alados, Concepción L.

2016-01-01

Over the last decades, global changes have altered the structure and properties of natural and semi-natural mountain grasslands. Those changes have contributed to grassland loss mainly through colonization by woody species at low elevations, and increases in biomass and greenness at high elevations. Nevertheless, the interactions between agropastoral components; i.e., ecological (grassland, environmental, and geolocation properties), social, and economic components, and their effects on the grasslands are still poorly understood. We estimated the vulnerability of dense grasslands in the Central Pyrenees, Spain, based on the connectivity loss (CL) among grassland patches that has occurred between the 1980s and the 2000s, as a result of i) an increase in biomass and greenness (CL-IBG), ii) woody encroachment (CL-WE), or iii) a decrease in biomass and greenness (CL-DBG). The environmental and grassland components of the agropastoral system were associated with the three processes, especially CL-IBG and CL-WE, in relation with the succession of vegetation toward climax communities, fostered by land abandonment and exacerbated by climate warming. CL-IBG occurred in pasture units that had a high proportion of dense grasslands and low current livestock pressure. CL-WE was most strongly associated with pasture units that had a high proportion of woody habitat and a large reduction in sheep and goat pressure between the 1930s and the 2000s. The economic component was correlated with the CL-WE and the CL-DBG; specifically, expensive pastures were the most productive and could maintain the highest rates of livestock grazing, which slowed down woody encroachment, but caused grassland degradation and DBG. In addition, CL-DBG was associated with geolocation of grasslands, mainly because livestock tend to graze closer to passable roads and buildings, where they cause grassland degradation. To properly manage the grasslands, an integrated management plan must be developed that includes an understanding of all components of the agropastoral system and takes into account all changes that have occurred in dense mountain grasslands. Addressing the problems individually risks the improvement of some grasslands and the deterioration of others. PMID:27171181

Influence of Agropastoral System Components on Mountain Grassland Vulnerability Estimated by Connectivity Loss.

PubMed

Gartzia, Maite; Fillat, Federico; Pérez-Cabello, Fernando; Alados, Concepción L

2016-01-01

Over the last decades, global changes have altered the structure and properties of natural and semi-natural mountain grasslands. Those changes have contributed to grassland loss mainly through colonization by woody species at low elevations, and increases in biomass and greenness at high elevations. Nevertheless, the interactions between agropastoral components; i.e., ecological (grassland, environmental, and geolocation properties), social, and economic components, and their effects on the grasslands are still poorly understood. We estimated the vulnerability of dense grasslands in the Central Pyrenees, Spain, based on the connectivity loss (CL) among grassland patches that has occurred between the 1980s and the 2000s, as a result of i) an increase in biomass and greenness (CL-IBG), ii) woody encroachment (CL-WE), or iii) a decrease in biomass and greenness (CL-DBG). The environmental and grassland components of the agropastoral system were associated with the three processes, especially CL-IBG and CL-WE, in relation with the succession of vegetation toward climax communities, fostered by land abandonment and exacerbated by climate warming. CL-IBG occurred in pasture units that had a high proportion of dense grasslands and low current livestock pressure. CL-WE was most strongly associated with pasture units that had a high proportion of woody habitat and a large reduction in sheep and goat pressure between the 1930s and the 2000s. The economic component was correlated with the CL-WE and the CL-DBG; specifically, expensive pastures were the most productive and could maintain the highest rates of livestock grazing, which slowed down woody encroachment, but caused grassland degradation and DBG. In addition, CL-DBG was associated with geolocation of grasslands, mainly because livestock tend to graze closer to passable roads and buildings, where they cause grassland degradation. To properly manage the grasslands, an integrated management plan must be developed that includes an understanding of all components of the agropastoral system and takes into account all changes that have occurred in dense mountain grasslands. Addressing the problems individually risks the improvement of some grasslands and the deterioration of others.

Ultrasensitive multiplex optical quantification of bacteria in large samples of biofluids

PubMed Central

Pazos-Perez, Nicolas; Pazos, Elena; Catala, Carme; Mir-Simon, Bernat; Gómez-de Pedro, Sara; Sagales, Juan; Villanueva, Carlos; Vila, Jordi; Soriano, Alex; García de Abajo, F. Javier; Alvarez-Puebla, Ramon A.

2016-01-01

Efficient treatments in bacterial infections require the fast and accurate recognition of pathogens, with concentrations as low as one per milliliter in the case of septicemia. Detecting and quantifying bacteria in such low concentrations is challenging and typically demands cultures of large samples of blood (~1 milliliter) extending over 24–72 hours. This delay seriously compromises the health of patients. Here we demonstrate a fast microorganism optical detection system for the exhaustive identification and quantification of pathogens in volumes of biofluids with clinical relevance (~1 milliliter) in minutes. We drive each type of bacteria to accumulate antibody functionalized SERS-labelled silver nanoparticles. Particle aggregation on the bacteria membranes renders dense arrays of inter-particle gaps in which the Raman signal is exponentially amplified by several orders of magnitude relative to the dispersed particles. This enables a multiplex identification of the microorganisms through the molecule-specific spectral fingerprints. PMID:27364357

Bouncing droplets on a billiard table.

PubMed

Shirokoff, David

2013-03-01

In a set of experiments, Couder et al. demonstrate that an oscillating fluid bed may propagate a bouncing droplet through the guidance of the surface waves. I present a dynamical systems model, in the form of an iterative map, for a droplet on an oscillating bath. I examine the droplet bifurcation from bouncing to walking, and prescribe general requirements for the surface wave to support stable walking states. I show that in addition to walking, there is a region of large forcing that may support the chaotic motion of the droplet. Using the map, I then investigate the droplet trajectories in a square (billiard ball) domain. I show that in large domains, the long time trajectories are either non-periodic dense curves or approach a quasiperiodic orbit. In contrast, in small domains, at low forcing, trajectories tend to approach an array of circular attracting sets. As the forcing increases, the attracting sets break down and the droplet travels throughout space.

A fast low-power optical memory based on coupled micro-ring lasers

NASA Astrophysics Data System (ADS)

Hill, Martin T.; Dorren, Harmen J. S.; de Vries, Tjibbe; Leijtens, Xaveer J. M.; den Besten, Jan Hendrik; Smalbrugge, Barry; Oei, Yok-Siang; Binsma, Hans; Khoe, Giok-Djan; Smit, Meint K.

2004-11-01

The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data. Recently, ring lasers with extremely small size and low operating power have been made, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 × 40µm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20ps with 5.5fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.

Ultrastructure of the synovial membrane in seronegative inflammatory arthropathies.

PubMed Central

Morris, C J; Farr, M; Hollywell, C A; Hawkins, C F; Scott, D L; Walton, K W

1983-01-01

The ultrastructure of the synovial membrane has been studied in 6 patients with seronegative inflammatory arthropathies: Reiter's (2), Crohn's (2), Whipple's (1) and Behçet's disease (1). The most striking changes were found in the synovial B cells, many containing abnormally large mitochondria with altered cristae surrounded by fibrillar material. Similar material was present in dilated endoplasmic reticulum which was the probable source of groups of extracellular fibrillar spheroidal bodies. The B cells also contained electron dense granular lysosomes of very variable size which, in common with the abnormal mitochondria, were often associated with bundles of orientated microfilaments and large golgi complexes. Light microscopy of the synovial membrane was consistent with an inflammatory arthritis, as were the high white cell counts in the synovial fluid. Systemic activity in the patients was indicated by raised ESR and C-reactive protein (CRP). Images Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. A Figure 5. B PMID:6186810

VizieR Online Data Catalog: Massive stars in 30 Dor (Schneider+, 2018)

NASA Astrophysics Data System (ADS)

Schneider, F. R. N.; Sana, H.; Evans, C. J.; Bestenlehner, J. M.; Castro, N.; Fossati, L.; Grafener, G.; Langer, N.; Ramirez-Agudelo, O. H.; Sabin-Sanjulian, C.; Simon-Diaz, S.; Tramper, F.; Crowther, P. A.; de Koter, A.; de Mink, S. E.; Dufton, P. L.; Garcia, M.; Gieles, M.; Henault-Brunet, V.; Herrero, A.; Izzard, R. G.; Kalari, V.; Lennon, D. J.; Apellaniz, J. M.; Markova, N.; Najarro, F.; Podsiadlowski, P.; Puls, J.; Taylor, W. D.; van Loon, J. T.; Vink, J. S.; Norman, C.

2018-02-01

Through the use of the Fibre Large Array Multi Element Spectrograph (FLAMES) on the Very Large Telescope (VLT), the VLT-FLAMES Tarantula Survey (VFTS) has obtained optical spectra of ~800 massive stars in 30 Dor, avoiding the core region of the dense star cluster R136 because of difficulties with crowding. Repeated observations at multiple epochs allow determination of the orbital motion of potentially binary objects. For a sample of 452 apparently single stars, robust stellar parameters-such as effective temperatures, luminosities, surface gravities, and projected rotational velocities-are determined by modeling the observed spectra. Composite spectra of visual multiple systems and spectroscopic binaries are not considered here because their parameters cannot be reliably inferred from the VFTS data. To match the derived atmospheric parameters of the apparently single VFTS stars to stellar evolutionary models, we use the Bayesian code Bonnsai. (2 data files).

Genome-wide association study identifies multiple loci associated with both mammographic density and breast cancer risk

PubMed Central

Lindström, Sara; Thompson, Deborah J.; Paterson, Andrew D.; Li, Jingmei; Gierach, Gretchen L.; Scott, Christopher; Stone, Jennifer; Douglas, Julie A.; dos-Santos-Silva, Isabel; Fernandez-Navarro, Pablo; Verghase, Jajini; Smith, Paula; Brown, Judith; Luben, Robert; Wareham, Nicholas J.; Loos, Ruth J.F.; Heit, John A.; Pankratz, V. Shane; Norman, Aaron; Goode, Ellen L.; Cunningham, Julie M.; deAndrade, Mariza; Vierkant, Robert A.; Czene, Kamila; Fasching, Peter A.; Baglietto, Laura; Southey, Melissa C.; Giles, Graham G.; Shah, Kaanan P.; Chan, Heang-Ping; Helvie, Mark A.; Beck, Andrew H.; Knoblauch, Nicholas W.; Hazra, Aditi; Hunter, David J.; Kraft, Peter; Pollan, Marina; Figueroa, Jonine D.; Couch, Fergus J.; Hopper, John L.; Hall, Per; Easton, Douglas F.; Boyd, Norman F.; Vachon, Celine M.; Tamimi, Rulla M.

2015-01-01

Mammographic density reflects the amount of stromal and epithelial tissues in relation to adipose tissue in the breast and is a strong risk factor for breast cancer. Here we report the results from meta-analysis of genome-wide association studies (GWAS) of three mammographic density phenotypes: dense area, non-dense area and percent density in up to 7,916 women in stage 1 and an additional 10,379 women in stage 2. We identify genome-wide significant (P<5×10−8) loci for dense area (AREG, ESR1, ZNF365, LSP1/TNNT3, IGF1, TMEM184B, SGSM3/MKL1), non-dense area (8p11.23) and percent density (PRDM6, 8p11.23, TMEM184B). Four of these regions are known breast cancer susceptibility loci, and four additional regions were found to be associated with breast cancer (P<0.05) in a large meta-analysis. These results provide further evidence of a shared genetic basis between mammographic density and breast cancer and illustrate the power of studying intermediate quantitative phenotypes to identify putative disease susceptibility loci. PMID:25342443

Time-resolved X-ray Absorption Spectroscopy for Electron Transport Study in Warm Dense Gold

NASA Astrophysics Data System (ADS)

Lee, Jong-Won; Bae, Leejin; Engelhorn, Kyle; Heimann, Philip; Ping, Yuan; Barbrel, Ben; Fernandez, Amalia; Beckwith, Martha Anne; Cho, Byoung-Ick; GIST Team; IBS Team; LBNL Collaboration; SLAC Collaboration; LLNL Collaboration

2015-11-01

The warm dense Matter represents states of which the temperature is comparable to Fermi energy and ions are strongly coupled. One of the experimental techniques to create such state in the laboratory condition is the isochoric heating of thin metal foil with femtosecond laser pulses. This concept largely relies on the ballistic transport of electrons near the Fermi-level, which were mainly studied for the metals in ambient conditions. However, they were barely investigated in warm dense conditions. We present a time-resolved x-ray absorption spectroscopy measured for the Au/Cu dual layered sample. The front Au layer was isochorically heated with a femtosecond laser pulse, and the x-ray absorption changes around L-edge of Cu, which was attached on the backside of Au, was measured with a picosecond resolution. Time delays between the heating of the `front surface' of Au layer and the alternation of x-ray spectrum of Cu attached on the `rear surface' of Au indicate the energetic electron transport mechanism through Au in the warm dense conditions. IBS (IBS-R012-D1) and the NRF (No. 2013R1A1A1007084) of Korea.

On the dense water cascading in the Southern Adriatic Sea during 2012: Setup of a Rapid Environmental Assessment

NASA Astrophysics Data System (ADS)

Langone, Leonardo

2013-04-01

In the North Adriatic, Dense Shelf Water (DSW) forms during cold and dry winters by cooling and evaporation. DSW spreads southward along the western shelf reaching the southern Adriatic basin (1200 m deep) after 1-2 months, where sinks through cascading events. In February 2012, a large Siberian High caused blocking of the Atlantic flow and a westward flow of dry and cold air masses from eastern Russia toward Europe. The North Adriatic experienced a cold spell with large decrease of surface temperature (3° -6° C) associated to severe cold and dry Bora wind. The result was the formation of extremely dense shelf water, further made possible by the very limited discharge of the Po river in the preceding autumn. As contribution to the Italian research programme RITMARE (Italian Research for the Sea), CNR-ISMAR set up a Rapid Environmental Assessment (REA) experiment to study the occurrence, amount, timing and properties of the newly formed DSW. Setting up REA strategies is crucial for several scientific and practical reasons: (i) capturing extreme events to improve our understanding of natural systems in a global-change scenario; (ii) to evaluate their impact on marine systems and the biota; (iii) to address issues related to fluctuating fish stocks as well as (iv) C export and sequestration in the deep sea. The experiment was designed with an integrated approach, including modeling simulations, mooring deployments and quick-response oceanographic cruises. Based on numerical model ensemble, the arrival time of the DSW at the Gargano Cape was forecasted likely starting after March 15, 2012, thus moorings were deployed few days before. Five moorings were deployed in sites selected on the basis of modelling predictions and geology-driven inferences defining areas where the passage of dense shelf water is most likely to occur. Moorings were equipped with down-looking ADCPs, automatic sediment traps, temperature loggers, recorders of temperature, conductivity and turbidity, and single point current-meters. Two rapid-response cruises were carried out by RV's MinervaUno and Urania in late-March and mid-April, respectively, in order to perform CTD profiles with LADCP, XBT transects and water sampling (TSM, dissolved and particulate matter, plankton, Bacteria and Archaea, etc.). Overall, the observations matched real-time modelling simulations. The DSW veins were located in the open slope off Gargano, and impacted a 100-km slope stretch all the way to Bari canyon. Speed and direction of currents at the bottom were consistent with the bedform distribution, also in the deepest part of the basin. Cascading was recorded to occur with multiple pulses (variability at daily scale), reaching speeds of 70 cm s-1. Several open questions on the cascading process can now be addressed based on the newly acquired data. As part of the research programme RITMARE, CNR-ISMAR is now engaged in the design and prolonged deployment of moorings to study the interannual variability in timing of initiation of the cascading process, which takes place every spring, its variability in intensity and duration and the ultimate impact of the dense water on the deep sea. Through this experiment we plan to gain elements to improve our understanding of future evolution of the process and the related possible regime shifts in a likely scenario of surface-water temperature increase over the entire Mediterranean.

Galactic Spiral Shocks with Thermal Instability in Vertically Stratified Disks

NASA Astrophysics Data System (ADS)

Kim, Chang-Goo; Kim, W.; Ostriker, E. C.

2010-01-01

Galactic spiral shocks are dominant morphological features and believed to be responsible for substructure formation of spiral arms in disk galaxies. They can also provide a large amount of kinetic energy for the interstellar gas by tapping the rotational energy. We use numerical hydrodynamic simulations to investigate dynamics and structure of spiral shocks with thermal instability in vertically stratified galactic disks. We initially consider an isothermal disk in vertical hydrostatic equilibrium and let it evolve under interstellar cooling and heating. Due to cooling and heating, the disk rapidly turns to a dense slab near the midplane surrounded by rarefied gas at high-altitude regions. The imposed stellar spiral potential develops a vertically curved shock that exhibits strong flapping motions along the direction perpendicular to the arm. The flows across the spiral shock are characterized by transitions from rarefied to dense phases at the shock and from dense to rarefied phases at the postshock expansion zone. The shock flapping motions stirs the disk, supplying the gas with random kinetic energy. For a model resembling the galactic disk near the solar neighborhood, the density-weighted vertical velocity dispersions are 2 km/s for the rarefied gas and 1 km/s for the dense gas. The shock compression in this model reduces an amount of the rarefied gas from 29% to 19% by mass. Despite the flapping motions, the time-averaged profiles of surface density are similar to those of the one-dimensional counterparts, and the vertical density distribution is overall consistent with effective hydrostatic equilibrium. When self-gravity is included, the shock compression forms large gravitationally bound condensations with virial ratio of about 2 and typical masses of 0.5 to one million solar masses, comparable to the Jeans mass.

From gas to stars in energetic environments: dense gas clumps in the 30 Doradus region within the Large Magellanic Cloud

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Crystal N.; Meier, David S.; Ott, Jürgen

2014-09-20

We present parsec-scale interferometric maps of HCN(1-0) and HCO{sup +}(1-0) emission from dense gas in the star-forming region 30 Doradus, obtained using the Australia Telescope Compact Array. This extreme star-forming region, located in the Large Magellanic Cloud (LMC), is characterized by a very intense ultraviolet ionizing radiation field and sub-solar metallicity, both of which are expected to impact molecular cloud structure. We detect 13 bright, dense clumps within the 30 Doradus-10 giant molecular cloud. Some of the clumps are aligned along a filamentary structure with a characteristic spacing that is consistent with formation via varicose fluid instability. Our analysis showsmore » that the filament is gravitationally unstable and collapsing to form stars. There is a good correlation between HCO{sup +} emission in the filament and signatures of recent star formation activity including H{sub 2}O masers and young stellar objects (YSOs). YSOs seem to continue along the same direction of the filament toward the massive compact star cluster R136 in the southwest. We present detailed comparisons of clump properties (masses, linewidths, and sizes) in 30Dor-10 to those in other star forming regions of the LMC (N159, N113, N105, and N44). Our analysis shows that the 30Dor-10 clumps have similar masses but wider linewidths and similar HCN/HCO{sup +} (1-0) line ratios as clumps detected in other LMC star-forming regions. Our results suggest that the dense molecular gas clumps in the interior of 30Dor-10 are well shielded against the intense ionizing field that is present in the 30 Doradus region.« less

Impact of portion size and energy density on snack intake in preschool-aged children.

PubMed

Looney, Shannon M; Raynor, Hollie A

2011-03-01

The influence of dietary environmental factors on child weight status may be important in the battle against childhood obesity. Portion size and energy density are factors shown to impact entrée energy intake in children. However, the influence of these factors on child snack energy intake has not been studied. Thus, the aim of this study was to investigate the impact of portion size on intake of a lower energy-dense and higher energy-dense snack in preschool-aged children. A 2×2 crossover design (within-subject factors of portion size and energy density) was conducted on Wednesdays in a preschool setting on the University of Tennessee campus from October 2008 to November 2008. Seventeen children had complete data (age 3.8±0.6 years; 10 of 17 were female; 14 of 17 were white). Foods were applesauce (lower energy dense=0.43 kcal/g) and chocolate pudding (higher energy dense=1.19 kcal/g), and portion sizes were 150 g (small) and 300 g (large). Measures included anthropometrics, hunger, liking of foods, and caretakers' child-feeding practices using validated instruments. Mixed factorial analyses of covariance, with order controlled, analyzed gram and energy snack intake across conditions. There was no significant main effect of energy density on snack intake, but the main effect of portion size on snack intake (small portion size 84.2±30.8 kcal, large portion size 99.0±52.5 kcal; P<0.05) was significant. Results indicate increased energy intake when snacks are offered in larger portion size, regardless of energy density. Snack portion size may be an environmental strategy that can reduce excessive energy intake in children. Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

Size and structure of Chlorella zofingiensis /FeCl 3 flocs in a shear flow: Algae Floc Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wyatt, Nicholas B.; O'Hern, Timothy J.; Shelden, Bion

Flocculation is a promising method to overcome the economic hurdle to separation of algae from its growth medium in large scale operations. But, understanding of the floc structure and the effects of shear on the floc structure are crucial to the large scale implementation of this technique. The floc structure is important because it determines, in large part, the density and settling behavior of the algae. Freshwater algae floc size distributions and fractal dimensions are presented as a function of applied shear rate in a Couette cell using ferric chloride as a flocculant. Comparisons are made with measurements made formore » a polystyrene microparticle model system taken here as well as reported literature results. The algae floc size distributions are found to be self-preserving with respect to shear rate, consistent with literature data for polystyrene. Moreover, three fractal dimensions are calculated which quantitatively characterize the complexity of the floc structure. Low shear rates result in large, relatively dense packed flocs which elongate and fracture as the shear rate is increased. Our results presented here provide crucial information for economically implementing flocculation as a large scale algae harvesting strategy.« less

A pilot scale ultrasonic system to enhance extraction processes with dense gases

NASA Astrophysics Data System (ADS)

Riera, E.; Blasco, M.; Tornero, A.; Casas, E.; Roselló, C.; Simal, S.; Acosta, V. M.; Gallego-Juárez, J. A.

2012-05-01

The use of dense gases (supercritical fluids) as extracting agents has been attracting wide interest for years. In particular, supercritical carbon dioxide is considered nowadays as a green and very useful solvent. Nevertheless, the extraction process has a slow dynamics. Power ultrasound represents an efficient way for accelerating and enhancing the kinetics of the process by producing strong agitation and turbulence, compressions and decompressions, and heating in the media. For this purpose, a device prototype for using ultrasound in supercritical media was developed, tested and validated in extraction processes of oil from grounded almonds (55% oil content, wet basis and 3-4 mm particle size) in a 5 L extraction unit. An amount of 1500 g of grounded almonds was placed in a cylindrical basket during the trials inside the dense gas extractor (DGE) where solvent was introduced at different flow rates, pressures and temperatures. In all cases the ultrasonic energy confirmed the enhancement and acceleration of the almond oil extraction kinetics using supercritical CO2. Presently the power ultrasound effect in such a process is being deeply analyzed in a 5 L extraction unit before scaling-up a new ultrasonic system. This technology, still under development, has been designed for a bigger dense gas pilot-plant consisting of two extractors (20 L capacity), two separation units and has the possibility of operating at a pressure up to 50 MPa. The goal of this work is to study the effect of high-power ultrasound coupled to dense gas extraction inside the basket with the product, and to present a prototype for the use of power ultrasound in extraction processes with dense gases inside a new 20 L extractor unit.

ELECTRON MICROSCOPY OF HELA CELLS INFECTED WITH ADENOVIRUSES

PubMed Central

Harford, Carl G.; Hamlin, Alice; Parker, Esther; van Ravenswaay, Theodore

1956-01-01

HeLa cells were infected with adenoviruses (types 1–4) and sectioned for electron microscopy after intervals of 20 to 48 hours. Clusters of virus-like particles were found within the nuclei of infected cultures but not in those of uninfected controls. The particles were often arranged in rows as if in crystalline formation. Maximal diameter of particles was approximately 65 mµ, and internal bodies were demonstrated. Lesions of infected cells included target-like structures of the nuclear membrane, large nuclear vacuoles (type 2), and increased numbers of large irregular electron-dense granules in the cytoplasm 48 hours after infection. Examination of infected cultures by light microscopy, using the Feulgen reaction, showed intranuclear inclusion bodies and a cytopathogenic effect consisting of clumping of cells without pyknosis of nuclei. A lipide stain showed numerous cytoplasmic granules that were not identical with the large, irregular, electron-dense granules of the cytoplasm. Practically all the cells showed the viral cytopathogenic effect, but only a minority of cells were found to contain virus-like particles or intranuclear inclusion bodies. PMID:13357696

Turbulent AGN tori .

NASA Astrophysics Data System (ADS)

Schartmann, M.; Meisenheimer, K.; Klahr, H.; Camenzind, M.; Wolf, S.; Henning, Th.

Recently, the MID-infrared Interferometric instrument (MIDI) at the VLTI has shown that dust tori in the two nearby Seyfert galaxies NGC 1068 and the Circinus galaxy are geometrically thick and can be well described by a thin, warm central disk, surrounded by a colder and fluffy torus component. By carrying out hydrodynamical simulations with the help of the TRAMP code \\citep{schartmann_Klahr_99}, we follow the evolution of a young nuclear star cluster in terms of discrete mass-loss and energy injection from stellar processes. This naturally leads to a filamentary large scale torus component, where cold gas is able to flow radially inwards. The filaments open out into a dense and very turbulent disk structure. In a post-processing step, we calculate observable quantities like spectral energy distributions or images with the help of the 3D radiative transfer code MC3D \\citep{schartmann_Wolf_03}. Good agreement is found in comparisons with data due to the existence of almost dust-free lines of sight through the large scale component and the large column densities caused by the dense disk.

Suppressing turbulence of self-propelling rods by strongly coupled passive particles.

PubMed

Su, Yen-Shuo; Wang, Hao-Chen; I, Lin

2015-03-01

The strong turbulence suppression, mainly for large-scale modes, of two-dimensional self-propelling rods, by increasing the long-range coupling strength Γ of low-concentration passive particles, is numerically demonstrated. It is found that large-scale collective rod motion in forms of swirls or jets is mainly contributed from well-aligned dense patches, which can push small poorly aligned rod patches and uncoupled passive particles. The more efficient momentum transfer and dissipation through increasing passive particle coupling leads to the formation of a more ordered and slowed down network of passive particles, which competes with coherent dense active rod clusters. The frustration of active rod alignment ordering and coherent motion by the passive particle network, which interrupt the inverse cascading of forming large-scale swirls, is the key for suppressing collective rod motion with scales beyond the interpassive distance, even in the liquid phase of passive particles. The loosely packed active rods are weakly affected by increasing passive particle coupling due to the weak rod-particle interaction. They mainly contribute to the small-scale modes and high-speed motion.

The morphology of the Martian surface

USGS Publications Warehouse

Carr, M.H.

1980-01-01

Most of the southern hemisphere of Mars is densely cratered and stands 1-3 km above the topographic datum. The northern hemisphere is more sparsely cratered and elevations are generally below the datum. A broad rise, the Tharsis bulge, centered at 14?? S, 101?? W, is 8000 km across and 10 km above the datum at its summit. The densely cratered terrain has two main components; very ancient crust, nearly saturated with large craters, and younger intercrater plains. In many areas the older unit is fractured and extensively dissected by small channels. The younger intercrater plains are distinctly layered in places and less dissected, less fractured, and less cratered. Both units probably date from very early in the planet's history. Cratered plains cover much of the northern hemisphere and are highly variegated. Those around the large volcanoes are covered with numerous volcanic flows whereas in other areas the plains are featureless except for craters and lunar mare-like ridges. Between 40?? N and 60?? N the plains are complex with various kinds of striped and patterned ground, low escarpments, and isolated irregularly shaped mesas. Their peculiar morphology has been attributed, in part, to the repeated deposition and removal of volatile-rich debris layers. Along the boundary between the northern plains and the densely cratered terrain to the south, the plains and cratered terrain complexly inter-finger. The old terrain forms the high ground and appears to have undergone mass wasting on a large scale. In several areas, particularly south of Chryse Planitia, the old, cratered surface has collapsed to form chaotic terrain. Large channels, tens of kilometers wide and hundreds of kilometers long, with numerous characteristics suggestive of catastrophic flooding, commonly emerge from the chaotic areas. Much of the area between 50?? W and 180?? W and 50?? N and 50?? S is cut by fractures radial to the center of the Tharsis bulge. The equatorial canyon system, Valles Marineris, is radial to the bulge and appears to have formed largely by faulting along the radial fractures, although it has also been extensively modified by various mass wasting and fluvial processes. Most but not all volcanoes are in the Tharsis and Elysium regions. The largest resemble terrestrial shield volcanoes except for scale; the edifices, flow features and calderas are all far larger than their terrestrial counterparts. Most impact craters on Mars are surrounded by layers of ejecta, each with a distil ridge. This unique morphology coupled with other surface characteristics suggests large amounts of ground ice. Layered deposits at both poles appear to be relatively young, volatile-rich, aeolian deposits. The north pole is also surrounded by a continuous belt of dunes several tens of kilometers across. In most other places, aeolian modification of the surface at a scale of several tens of meters appears slight despite annual global dust storms. ?? 1980 D. Reidel Publishing Co.

Boiling-over dense pyroclastic density currents during the formation of the 100 km3 Huichapan ignimbrite in Central Mexico: Stratigraphic and lithofacies analysis

NASA Astrophysics Data System (ADS)

Pacheco-Hoyos, Jaime G.; Aguirre-Díaz, Gerardo J.; Dávila-Harris, Pablo

2018-01-01

A lithofacies analysis of the Huichapan ignimbrite has been undertaken to evaluate its depositional history from large pyroclastic density currents. The Huichapan ignimbrite is a massive ignimbrite sheet with a maximum runout of at least 55 km and thickness variations between 6 and 80 m. The lower portion of the Huichapan ignimbrite consists of a large plateau [ 100 km3; 69 km3 as dense-rock equivalent (DRE)] of massive ignimbrites with welding variations from densely welded to partly welded, devitrification, and high-temperature vapor-phase alteration. The lower part grades laterally to moderately welded and non-devitrified ignimbrites. These variations are interpreted as the sedimentation of density-stratified pyroclastic density currents erupted as boiling-over pulses from the Huichapan-Donguinyó caldera complex at a continuous rate, supporting deposition by quasi-steady progressive aggradation of sustained and hot currents. To the north of the caldera, the lower portion of the ignimbrite consists of a small plateau (< 10 km3) in which the densely welded and devitrified lithofacies are absent. Our interpretation is that the pyroclastic density currents flowed late to the north of the caldera and formed a smaller ignimbrite plateau with respect to the western one. This northern ignimbrite plateau cooled faster than the western ignimbrite plateau. Deposition-induced topographic modifications suggest that topographic obstacles, such as remnants of older volcanoes, may have promoted the deviation of the density currents to the north. The upper portion of the ignimbrite is composed of extensive, massive, coarse clast-rich, non-devitrified, and non-welded ignimbrites with abundant fines-poor pipes. This upper part was deposited from largely sustained and rapidly aggrading high-concentration currents in a near end-member, fluid escape-dominated flow boundary zone. The absence of welding in the upper portion may record pyroclastic density currents cooling during the formation of a relatively high pyroclastic fountain at the vent. We have established a depositional model for the Huichapan ignimbrite that explains the differences between the western and northern plateaus. The Huichapan ignimbrite was formed during a large caldera-forming eruption with concentrated pyroclastic fountains. High mass-flow rate was maintained for long periods, promoting the mobility of the pyroclastic density currents.

Development and characterization of a high yield transportable pulsed neutron source with efficient and compact pulsed power system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verma, Rishi, E-mail: rishiv9@gmail.com, E-mail: rishiv@barc.gov.in; Mishra, Ekansh; Dhang, Prosenjit

2016-09-15

The results of characterization experiments carried out on a newly developed dense plasma focus device based intense pulsed neutron source with efficient and compact pulsed power system are reported. Its high current sealed pseudospark switch based low inductance capacitor bank with maximum stored energy of ∼10 kJ is segregated into four modules of ∼2.5 kJ each and it cumulatively delivers peak current in the range of 400 kA–600 kA (corresponding to charging voltage range of 14 kV–18 kV) in a quarter time period of ∼2 μs. The neutron yield performance of this device has been optimized by discretely varying deuteriummore » filling gas pressure in the range of 6 mbar–11 mbar at ∼17 kV/550 kA discharge. At ∼7 kJ/8.5 mbar operation, the average neutron yield has been measured to be in the order of ∼4 × 10{sup 9} neutrons/pulse which is the highest ever reported neutron yield from a plasma focus device with the same stored energy. The average forward to radial anisotropy in neutron yield is found to be ∼2. The entire system is contained on a moveable trolley having dimensions 1.5 m × 1 m × 0.7 m and its operation and control (up to the distance of 25 m) are facilitated through optically isolated handheld remote console. The overall compactness of this system provides minimum proximity to small as well as large samples for irradiation. The major intended application objective of this high neutron yield dense plasma focus device development is to explore the feasibility of active neutron interrogation experiments by utilization of intense pulsed neutron sources.« less

Dense-array concentrator photovoltaic system using non-imaging dish concentrator and crossed compound parabolic concentrator

NASA Astrophysics Data System (ADS)

Chong, Kok-Keong; Yew, Tiong-Keat; Wong, Chee-Woon; Tan, Ming-Hui; Tan, Woei-Chong; Lai, An-Chow; Lim, Boon-Han; Lau, Sing-Liong; Rahman, Faidz Abdul

2015-04-01

Solar concentrating device plays an important role by making use of optical technology in the design, which can be either reflector or lens to deliver high flux of sunlight onto the Concentrator Photovoltaic (CPV) module receiver ranging from hundreds to thousand suns. To be more competitive compared with fossil fuel, the current CPV systems using Fresnel lens and Parabolic dish as solar concentrator that are widely deployed in United States, Australia and Europe are facing great challenge to produce uniformly focused sunlight on the solar cells as to reduce the cost of electrical power generation. The concept of non-imaging optics is not new, but it has not fully explored by the researchers over the world especially in solving the problem of high concentration solar energy, which application is only limited to be a secondary focusing device or low concentration device using Compound Parabolic Concentrator. With the current advancement in the computer processing power, we has successfully invented the non-imaging dish concentrator (NIDC) using numerical simulation method to replace the current parabolic dish as primary focusing device with high solar concentration ratio (more than 400 suns) and large collective area (from 25 to 125 m2). In this paper, we disclose our research and development on dense array CPV system based on non-imaging optics. The geometry of the NIDC is determined using a special computational method. In addition, an array of secondary concentrators, namely crossed compound parabolic concentrators, is also proposed to further focus the concentrated sunlight by the NIDC onto active area of solar cells of the concentrator photovoltaic receiver. The invention maximizes the absorption of concentrated sunlight for the electric power generation system.

Development and characterization of a high yield transportable pulsed neutron source with efficient and compact pulsed power system.

PubMed

Verma, Rishi; Mishra, Ekansh; Dhang, Prosenjit; Sagar, Karuna; Meena, Manraj; Shyam, Anurag

2016-09-01

The results of characterization experiments carried out on a newly developed dense plasma focus device based intense pulsed neutron source with efficient and compact pulsed power system are reported. Its high current sealed pseudospark switch based low inductance capacitor bank with maximum stored energy of ∼10 kJ is segregated into four modules of ∼2.5 kJ each and it cumulatively delivers peak current in the range of 400 kA-600 kA (corresponding to charging voltage range of 14 kV-18 kV) in a quarter time period of ∼2 μs. The neutron yield performance of this device has been optimized by discretely varying deuterium filling gas pressure in the range of 6 mbar-11 mbar at ∼17 kV/550 kA discharge. At ∼7 kJ/8.5 mbar operation, the average neutron yield has been measured to be in the order of ∼4 × 10 9 neutrons/pulse which is the highest ever reported neutron yield from a plasma focus device with the same stored energy. The average forward to radial anisotropy in neutron yield is found to be ∼2. The entire system is contained on a moveable trolley having dimensions 1.5 m × 1 m × 0.7 m and its operation and control (up to the distance of 25 m) are facilitated through optically isolated handheld remote console. The overall compactness of this system provides minimum proximity to small as well as large samples for irradiation. The major intended application objective of this high neutron yield dense plasma focus device development is to explore the feasibility of active neutron interrogation experiments by utilization of intense pulsed neutron sources.

Remodeling of nuclear architecture by the thiodioxoxpiperazine metabolite chaetocin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Illner, Doris; Zinner, Roman; Handtke, Violet

2010-06-10

Extensive changes of higher order chromatin arrangements can be observed during prometaphase, terminal cell differentiation and cellular senescence. Experimental systems where major reorganization of nuclear architecture can be induced under defined conditions, may help to better understand the functional implications of such changes. Here, we report on profound chromatin reorganization in fibroblast nuclei by chaetocin, a thiodioxopiperazine metabolite. Chaetocin induces strong condensation of chromosome territories separated by a wide interchromatin space largely void of DNA. Cell viability is maintained irrespective of this peculiar chromatin phenotype. Cell cycle markers, histone signatures, and tests for cellular senescence and for oxidative stress indicatemore » that chaetocin induced chromatin condensation/clustering (CICC) represents a distinct entity among nuclear phenotypes associated with condensed chromatin. The territorial organization of entire chromosomes is maintained in CICC nuclei; however, the conventional nuclear architecture harboring gene-dense chromatin in the nuclear interior and gene-poor chromatin at the nuclear periphery is lost. Instead gene-dense and transcriptionally active chromatin is shifted to the periphery of individual condensed chromosome territories where nascent RNA becomes highly enriched around their outer surface. This chromatin reorganization makes CICC nuclei an attractive model system to study this border zone as a distinct compartment for transcription. Induction of CICC is fully inhibited by thiol-dependent antioxidants, but is not related to the production of reactive oxygen species. Our results suggest that chaetocin functionally impairs the thioredoxin (Trx) system, which is essential for deoxynucleotide synthesis, but in addition involved in a wide range of cellular functions. The mechanisms involved in CICC formation remain to be fully explored.« less

A network model framework for prioritizing wetland conservation in the Great Plains

USGS Publications Warehouse

Albanese, Gene; Haukos, David A.

2017-01-01

ContextPlaya wetlands are the primary habitat for numerous wetland-dependent species in the Southern Great Plains of North America. Plant and wildlife populations that inhabit these wetlands are reciprocally linked through the dispersal of individuals, propagules and ultimately genes among local populations.ObjectiveTo develop and implement a framework using network models for conceptualizing, representing and analyzing potential biological flows among 48,981 spatially discrete playa wetlands in the Southern Great Plains.MethodsWe examined changes in connectivity patterns and assessed the relative importance of wetlands to maintaining these patterns by targeting wetlands for removal based on network centrality metrics weighted by estimates of habitat quality and probability of inundation.ResultsWe identified several distinct, broad-scale sub networks and phase transitions among playa wetlands in the Southern Plains. In particular, for organisms that can disperse >2 km a dense and expansive wetland sub network emerges in the Southern High Plains. This network was characterized by localized, densely connected wetland clusters at link distances (h) >2 km but <5 km and was most sensitive to changes in wetland availability (p) and configuration when h = 4 km, and p = 0.2–0.4. It transitioned to a single, large connected wetland system at broader spatial scales even when the proportion of inundated wetland was relatively low (p = 0.2).ConclusionsOur findings suggest that redundancy in the potential for broad and fine-scale movements insulates this system from damage and facilitates system-wide connectivity among populations with different dispersal capacities.

A Large-Particle Monte Carlo Code for Simulating Non-Linear High-Energy Processes Near Compact Objects

NASA Technical Reports Server (NTRS)

Stern, Boris E.; Svensson, Roland; Begelman, Mitchell C.; Sikora, Marek

1995-01-01

High-energy radiation processes in compact cosmic objects are often expected to have a strongly non-linear behavior. Such behavior is shown, for example, by electron-positron pair cascades and the time evolution of relativistic proton distributions in dense radiation fields. Three independent techniques have been developed to simulate these non-linear problems: the kinetic equation approach; the phase-space density (PSD) Monte Carlo method; and the large-particle (LP) Monte Carlo method. In this paper, we present the latest version of the LP method and compare it with the other methods. The efficiency of the method in treating geometrically complex problems is illustrated by showing results of simulations of 1D, 2D and 3D systems. The method is shown to be powerful enough to treat non-spherical geometries, including such effects as bulk motion of the background plasma, reflection of radiation from cold matter, and anisotropic distributions of radiating particles. It can therefore be applied to simulate high-energy processes in such astrophysical systems as accretion discs with coronae, relativistic jets, pulsar magnetospheres and gamma-ray bursts.

Identifying women with dense breasts at high risk for interval cancer: a cohort study.

PubMed

Kerlikowske, Karla; Zhu, Weiwei; Tosteson, Anna N A; Sprague, Brian L; Tice, Jeffrey A; Lehman, Constance D; Miglioretti, Diana L

2015-05-19

Twenty-one states have laws requiring that women be notified if they have dense breasts and that they be advised to discuss supplemental imaging with their provider. To better direct discussions of supplemental imaging by determining which combinations of breast cancer risk and Breast Imaging Reporting and Data System (BI-RADS) breast density categories are associated with high interval cancer rates. Prospective cohort. Breast Cancer Surveillance Consortium (BCSC) breast imaging facilities. 365,426 women aged 40 to 74 years who had 831,455 digital screening mammography examinations. BI-RADS breast density, BCSC 5-year breast cancer risk, and interval cancer rate (invasive cancer ≤12 months after a normal mammography result) per 1000 mammography examinations. High interval cancer rate was defined as more than 1 case per 1000 examinations. High interval cancer rates were observed for women with 5-year risk of 1.67% or greater and extremely dense breasts or 5-year risk of 2.50% or greater and heterogeneously dense breasts (24% of all women with dense breasts). The interval rate of advanced-stage disease was highest (>0.4 case per 1000 examinations) among women with 5-year risk of 2.50% or greater and heterogeneously or extremely dense breasts (21% of all women with dense breasts). Five-year risk was low to average (0% to 1.66%) for 51.0% of women with heterogeneously dense breasts and 52.5% with extremely dense breasts, with interval cancer rates of 0.58 to 0.63 and 0.72 to 0.89 case per 1000 examinations, respectively. The benefit of supplemental imaging was not assessed. Breast density should not be the sole criterion for deciding whether supplemental imaging is justified because not all women with dense breasts have high interval cancer rates. BCSC 5-year risk combined with BI-RADS breast density can identify women at high risk for interval cancer to inform patient-provider discussions about alternative screening strategies. National Cancer Institute.

Final Technical Report for Automated Manufacturing of Innovative CPV/PV Modules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okawa, David

Cogenra’s Dense Cell Interconnect system was designed to use traditional front-contact cells and string them together into high efficiency and high reliability “supercells”. This novel stringer allows one to take advantage of the ~100 GW/year of existing cell production capacity and create a solar product for the customer that will produce more power and last longer than traditional PV products. The goal for this program was for Cogenra Solar to design and develop a first-of-kind automated solar manufacturing line that produces strings of overlapping cells or “supercells” based on Cogenra’s Dense Cell Interconnect (DCI) technology for their Low Concentration Photovoltaicmore » (LCPV) systems. This will enable the commercialization of DCI technology to improve the efficiency, reliability and economics for their Low Concentration Photovoltaic systems. In this program, Cogenra Solar very successfully designed, developed, built, installed, and started up the ground-breaking manufacturing tools required to assemble supercells. Cogenra then successfully demonstrated operation of the integrated line at high yield and throughput far exceeding expectations. The development of a supercell production line represents a critical step toward a high volume and low cost Low Concentration Photovoltaic Module with Dense Cell Interconnect technology and has enabled the evaluation of the technology for reliability and yield. Unfortunately, performance and cost headwinds on Low Concentration Photovoltaics systems including lack of diffuse capture (10-15% hit) and more expensive tracker requirements resulted in a move away from LCPV technology. Fortunately, the versatility of Dense Cell Interconnect technology allows for application to flat plate module technology as well and Cogenra has worked with the DOE to utilize the learning from this grant to commercialize DCI technology for the solar market through the on-going grant: Catalyzing PV Manufacturing in the US With Cogenra Solar’s Next-Generation Dense Cell Interconnect PV Module Manufacturing Technology. This program is now very successfully building off of this work and commercializing the technology to enable increased solar adoption.« less

Array-type miniature interferometer as the core optical microsystem of an optical coherence tomography device for tissue inspection

NASA Astrophysics Data System (ADS)

Passilly, Nicolas; Perrin, Stéphane; Lullin, Justine; Albero, Jorge; Bargiel, Sylwester; Froehly, Luc; Gorecki, Christophe; Krauter, Johann; Osten, Wolfgang; Wang, Wei-Shan; Wiemer, Maik

2016-04-01

Some of the critical limitations for widespread use in medical applications of optical devices, such as confocal or optical coherence tomography (OCT) systems, are related to their cost and large size. Indeed, although quite efficient systems are available on the market, e.g. in dermatology, they equip only a few hospitals and hence, are far from being used as an early detection tool, for instance in screening of patients for early detection of cancers. In this framework, the VIAMOS project aims at proposing a concept of miniaturized, batch-fabricated and lower-cost, OCT system dedicated to non-invasive skin inspection. In order to image a large skin area, the system is based on a full-field approach. Moreover, since it relies on micro-fabricated devices whose fields of view are limited, 16 small interferometers are arranged in a dense array to perform multi-channel simultaneous imaging. Gaps between each channel are then filled by scanning of the system followed by stitching. This approach allows imaging a large area without the need of large optics. It also avoids the use of very fast and often expensive laser sources, since instead of a single point detector, almost 250 thousands pixels are used simultaneously. The architecture is then based on an array of Mirau interferometers which are interesting for their vertical arrangement compatible with vertical assembly at the wafer-level. Each array is consequently a local part of a stack of seven wafers. This stack includes a glass lens doublet, an out-of-plane actuated micro-mirror for phase shifting, a spacer and a planar beam-splitter. Consequently, different materials, such as silicon and glass, are bonded together and well-aligned thanks to lithographic-based fabrication processes.

Processing and mechanical characterization of alumina laminates

NASA Astrophysics Data System (ADS)

Montgomery, John K.

2002-08-01

Single-phase ceramics that combine property gradients or steps in monolithic bodies are sought as alternatives to ceramic composites made of dissimilar materials. This work describes novel processing methods to produce stepped-density (or laminated) alumina single-phase bodies that maintain their mechanical integrity. One arrangement consists of a stiff, dense bulk material with a thin, flaw tolerant, porous exterior layer. Another configuration consists of a lightweight, low-density bulk material with a thin, hard, wear resistant exterior layer. Alumina laminates with strong interfaces have been successfully produced in this work using two different direct-casting processes. Gelcasting is a useful near-net shape processing technique that has been combined with several techniques, such as reaction bonding of aluminum oxide and the use of starch as a fugative filler, to successfully produced stepped-density alumina laminates. The other direct casting process that has been developed in this work is thermoreversible gelcasting (TRG). This is a reversible gelation process that has been used to produce near-net shape dense ceramic bodies. Also, individual layers can be stacked together and heated to produce laminates. Bilayer laminate samples were produced with varied thickness of porous and dense layers. It was shown that due to the difference in modulus and hardness, transverse cracking is found upon Hertzian contact when the dense layer is on the exterior. In the opposite arrangement, compacted damage zones formed in the porous material and no damage occurred in the underlying dense layer. Flaw tolerant behavior of the porous exterior/dense underlayer was examined by measuring biaxial strength as a function of Vickers indentation load. It was found that the thinnest layer of porous material results in the greatest flaw tolerance. Also, higher strength was exhibited at large indentation loads when compared to dense monoliths. The calculated stresses on the surfaces and interface afforded an explanation of the behavior that failure initiates at the interface between the layers for the thinnest configuration, rather than the sample surface.

Dense Cores in Galaxies Out to z = 2.5 in SDSS, UltraVISTA, and the Five 3D-HST/CANDELS Fields

NASA Astrophysics Data System (ADS)

van Dokkum, Pieter G.; Bezanson, Rachel; van der Wel, Arjen; Nelson, Erica June; Momcheva, Ivelina; Skelton, Rosalind E.; Whitaker, Katherine E.; Brammer, Gabriel; Conroy, Charlie; Förster Schreiber, Natascha M.; Fumagalli, Mattia; Kriek, Mariska; Labbé, Ivo; Leja, Joel; Marchesini, Danilo; Muzzin, Adam; Oesch, Pascal; Wuyts, Stijn

2014-08-01

The dense interiors of massive galaxies are among the most intriguing environments in the universe. In this paper,we ask when these dense cores were formed and determine how galaxies gradually assembled around them. We select galaxies that have a stellar mass >3 × 1010 M ⊙ inside r = 1 kpc out to z = 2.5, using the 3D-HST survey and data at low redshift. Remarkably, the number density of galaxies with dense cores appears to have decreased from z = 2.5 to the present. This decrease is probably mostly due to stellar mass loss and the resulting adiabatic expansion, with some contribution from merging. We infer that dense cores were mostly formed at z > 2.5, consistent with their largely quiescent stellar populations. While the cores appear to form early, the galaxies in which they reside show strong evolution: their total masses increase by a factor of 2-3 from z = 2.5 to z = 0 and their effective radii increase by a factor of 5-6. As a result, the contribution of dense cores to the total mass of the galaxies in which they reside decreases from ~50% at z = 2.5 to ~15% at z = 0. Because of their early formation, the contribution of dense cores to the total stellar mass budget of the universe is a strong function of redshift. The stars in cores with M 1 kpc > 3 × 1010 M ⊙ make up ~0.1% of the stellar mass density of the universe today but 10%-20% at z ~ 2, depending on their initial mass function. The formation of these cores required the conversion of ~1011 M ⊙ of gas into stars within ~1 kpc, while preventing significant star formation at larger radii.

Electronic transport coefficients from ab initio simulations and application to dense liquid hydrogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holst, Bastian; French, Martin; Redmer, Ronald

2011-06-15

Using Kubo's linear response theory, we derive expressions for the frequency-dependent electrical conductivity (Kubo-Greenwood formula), thermopower, and thermal conductivity in a strongly correlated electron system. These are evaluated within ab initio molecular dynamics simulations in order to study the thermoelectric transport coefficients in dense liquid hydrogen, especially near the nonmetal-to-metal transition region. We also observe significant deviations from the widely used Wiedemann-Franz law, which is strictly valid only for degenerate systems, and give an estimate for its valid scope of application toward lower densities.

The Effects of Stellar Dynamics on the Evolution of Young, Dense Stellar Systems

NASA Astrophysics Data System (ADS)

Belkus, H.; van Bever, J.; Vanbeveren, D.

In this paper, we report on first results of a project in Brussels in which we study the effects of stellar dynamics on the evolution of young dense stellar systems using 3 decades of expertise in massive-star evolution and our population (number and spectral) synthesis code. We highlight an unconventionally formed object scenario (UFO-scenario) for Wolf Rayet binaries and study the effects of a luminous blue variable-type instability wind mass-loss formalism on the formation of intermediate-mass black holes.

Chimera-like states in structured heterogeneous networks

NASA Astrophysics Data System (ADS)

Li, Bo; Saad, David

2017-04-01

Chimera-like states are manifested through the coexistence of synchronous and asynchronous dynamics and have been observed in various systems. To analyze the role of network topology in giving rise to chimera-like states, we study a heterogeneous network model comprising two groups of nodes, of high and low degrees of connectivity. The architecture facilitates the analysis of the system, which separates into a densely connected coherent group of nodes, perturbed by their sparsely connected drifting neighbors. It describes a synchronous behavior of the densely connected group and scaling properties of the induced perturbations.

The Gardos channel is responsible for CDNB-induced dense sickle cell formation.

PubMed

Shartava, A; McIntyre, J; Shah, A K; Goodman, S R

2000-07-01

The red blood cells (RBCs) derived from blood taken from homozygous sickle cell (SS) patients demonstrate densities that are inversely proportional to the intracellular reduced glutathione (GSH) content. Addition of 1 mM 1-chloro-2,4-dinitrobenzene (CDNB) to low-density sickle cells (LDSS), at 4 degrees C, results in a shift of LDSS erythrocytes to high-density sickle cells (HDSS), with corresponding decreases in GSH. We have previously demonstrated that this CDNB effect was due to increased K(+) leakage and that dense cell formation could be inhibited by clotrimazole (specific for the Gardos channel) but not DIOA (specific for the K(+)-Cl(-) co-transport system) at pH 7.4 (Shartava et al. Am. J. Hematol. 1999;62:19-24). Here we demonstrate that clotrimazole (10 microM) inhibits dense cell formation at pH 7.1 and 6.8, while DIOA (1 mM) has no effect. As pH 6.8 is the optimal pH for the K(+)-Cl(-) co-transport system, we can now reasonably conclude that damage to the Gardos channel is responsible for CDNB-induced dense cell formation. Copyright 2000 Wiley-Liss, Inc.

OH megamasers: dense gas & the infrared radiation field

NASA Astrophysics Data System (ADS)

Huang, Yong; Zhang, JiangShui; Liu, Wei; Xu, Jie

2018-06-01

To investigate possible factors related to OH megamaser formation (OH MM, L_{H2O}>10L_{⊙}), we compiled a large HCN sample from all well-sampled HCN measurements so far in local galaxies and identified with the OH MM, OH kilomasers (L_{H2O}<10L_{⊙}, OH kMs), OH absorbers and OH non-detections (non-OH MM). Through comparative analysis on their infrared emission, CO and HCN luminosities (good tracers for the low-density gas and the dense gas, respectively), we found that OH MM galaxies tend to have stronger HCN emission and no obvious difference on CO luminosity exists between OH MM and non-OH MM. This implies that OH MM formation should be related to the dense molecular gas, instead of the low-density molecular gas. It can be also supported by other facts: (1) OH MMs are confirmed to have higher mean molecular gas density and higher dense gas fraction (L_{HCN}/L_{CO}) than non-OH MMs. (2) After taking the distance effect into account, the apparent maser luminosity is still correlated with the HCN luminosity, while no significant correlation can be found at all between the maser luminosity and the CO luminosity. (3) The OH kMs tend to have lower values than those of OH MMs, including the dense gas luminosity and the dense gas fraction. (4) From analysis of known data of another dense gas tracer HCO^+, similar results can also be obtained. However, from our analysis, the infrared radiation field can not be ruled out for the OH MM trigger, which was proposed by previous works on one small sample (Darling in ApJ 669:L9, 2007). On the contrary, the infrared radiation field should play one more important role. The dense gas (good tracers of the star formation) and its surrounding dust are heated by the ultra-violet (UV) radiation generated by the star formation and the heating of the high-density gas raises the emission of the molecules. The infrared radiation field produced by the re-radiation of the heated dust in turn serves for the pumping of the OH MM.

Prevalence of Mammographically Dense Breasts in the United States

PubMed Central

Gangnon, Ronald E.; Burt, Veronica; Trentham-Dietz, Amy; Hampton, John M.; Wellman, Robert D.; Kerlikowske, Karla; Miglioretti, Diana L.

2014-01-01

Background National legislation is under consideration that would require women with mammographically dense breasts to be informed of their breast density and encouraged to discuss supplemental breast cancer screening with their health care providers. The number of US women potentially affected by this legislation is unknown. Methods We determined the mammographic breast density distribution by age and body mass index (BMI) using data from 1518 599 mammograms conducted from 2007 through 2010 at mammography facilities in the Breast Cancer Surveillance Consortium (BCSC). We applied these breast density distributions to age- and BMI-specific counts of the US female population derived from the 2010 US Census and the National Health and Nutrition Examination Survey (NHANES) to estimate the number of US women with dense breasts. Results Overall, 43.3% (95% confidence interval [CI] = 43.1% to 43.4%) of women 40 to 74 years of age had heterogeneously or extremely dense breasts, and this proportion was inversely associated with age and BMI. Based on the age and BMI distribution of US women, we estimated that 27.6 million women (95% CI = 27.5 to 27.7 million) aged 40 to 74 years in the United States have heterogeneously or extremely dense breasts. Women aged 40 to 49 years (N = 12.3 million) accounted for 44.3% of this group. Conclusion The prevalence of dense breasts among US women of common breast cancer screening ages exceeds 25 million. Policymakers and healthcare providers should consider this large prevalence when debating breast density notification legislation and designing strategies to ensure that women who are notified have opportunities to evaluate breast cancer risk and discuss and pursue supplemental screening options if deemed appropriate. PMID:25217577

Dense understory dwarf bamboo alters the retention of canopy tree seeds

NASA Astrophysics Data System (ADS)

Qian, Feng; Zhang, Tengda; Guo, Qinxue; Tao, Jianping

2016-05-01

Tree seed retention is thought to be an important factor in the process of forest community regeneration. Although dense understory dwarf bamboo has been considered to have serious negative effects on the regeneration of forest community species, little attention has been paid to the relationship between dwarf bamboo and seed retention. In a field experiment we manipulated the density of Fargesia decurvata, a common understory dwarf bamboo, to investigate the retention of seeds from five canopy tree species in an evergreen and deciduous broad-leaved mixed forest in Jinfoshan National Nature Reserve, SW China. We found that the median survival time and retention ratio of seeds increased with the increase in bamboo density. Fauna discriminately altered seed retention in bamboo groves of different densities. Arthropods reduced seed survival the most, and seeds removed decreased with increasing bamboo density. Birds removed or ate more seeds in groves of medium bamboo density and consumed fewer seeds in dense or sparse bamboo habitats. Rodents removed a greater number of large and highly profitable seeds in dense bamboo groves but more small and thin-husked seeds in sparse bamboo groves. Seed characteristics, including seed size, seed mass and seed profitability, were important factors affecting seed retention. The results suggested that dense understory dwarf bamboo not only increased seeds concealment and reduced the probability and speed of seed removal but also influenced the trade-off between predation and risk of animal predatory strategies, thereby impacting the quantity and composition of surviving seeds. Our results also indicated that dense understory dwarf bamboo and various seed characteristics can provide good opportunities for seed storage and seed germination and has a potential positive effect on canopy tree regeneration.

Experimental evidence of exciton-plasmon coupling in densely packed dye doped core-shell nanoparticles obtained via microfluidic technique

NASA Astrophysics Data System (ADS)

De Luca, A.; Iazzolino, A.; Salmon, J.-B.; Leng, J.; Ravaine, S.; Grigorenko, A. N.; Strangi, G.

2014-09-01

The interplay between plasmons and excitons in bulk metamaterials are investigated by performing spectroscopic studies, including variable angle pump-probe ellipsometry. Gain functionalized gold nanoparticles have been densely packed through a microfluidic chip, representing a scalable process towards bulk metamaterials based on self-assembly approach. Chromophores placed at the hearth of plasmonic subunits ensure exciton-plasmon coupling to convey excitation energy to the quasi-static electric field of the plasmon states. The overall complex polarizability of the system, probed by variable angle spectroscopic ellipsometry, shows a significant modification under optical excitation, as demonstrated by the behavior of the ellipsometric angles Ψ and Δ as a function of suitable excitation fields. The plasmon resonances observed in densely packed gain functionalized core-shell gold nanoparticles represent a promising step to enable a wide range of electromagnetic properties and fascinating applications of plasmonic bulk systems for advanced optical materials.

A Roadmap of Innovative Nuclear Energy System

NASA Astrophysics Data System (ADS)

Sekimoto, Hiroshi

2017-01-01

Nuclear is a dense energy without CO2 emission. It can be used for more than 100,000 years using fast breeder reactors with uranium from the sea. However, it raises difficult problems associated with severe accidents, spent fuel waste and nuclear threats, which should be solved with acceptable costs. Some innovative reactors have attracted interest, and many designs have been proposed for small reactors. These reactors are considered much safer than conventional large reactors and have fewer technical obstructions. Breed-and-burn reactors have high potential to solve all inherent problems for peaceful use of nuclear energy. However, they have some technical problems with materials. A roadmap for innovative reactors is presented herein.

Recent advances in multiview distributed video coding

NASA Astrophysics Data System (ADS)

Dufaux, Frederic; Ouaret, Mourad; Ebrahimi, Touradj

2007-04-01

We consider dense networks of surveillance cameras capturing overlapped images of the same scene from different viewing directions, such a scenario being referred to as multi-view. Data compression is paramount in such a system due to the large amount of captured data. In this paper, we propose a Multi-view Distributed Video Coding approach. It allows for low complexity / low power consumption at the encoder side, and the exploitation of inter-view correlation without communications among the cameras. We introduce a combination of temporal intra-view side information and homography inter-view side information. Simulation results show both the improvement of the side information, as well as a significant gain in terms of coding efficiency.

A Jamming Phase Diagram for Pressing Polymers

NASA Astrophysics Data System (ADS)

Teng, Chao; Zhang, Zexin; Wang, Xiaoliang; Xue, Gi; Nanjing University Team; Soochow University Collaboration

2011-03-01

Molecular glasses begin to flow when they are heated. Other glassy systems, such as dense foams, emulsions, colloidal suspensions and granular materials, begin to flow when subjected to sufficiently large stresses. The equivalence of these two routes to flow is a basic tenet of jamming, a conceptual means of unifying glassy behavior in a swath of disordered, dynamical arrested systems. However, a full understanding of jamming transition for polymers remains elusive. By controlling the packing densities of polymer glasses, we found that polymer glasses could once flow under cold-pressing at temperatures well below its calorimetric glass transition temperature (Tg). The thermomechanical analysis (TMA) results confirmed that Tg changed with density as well as the applied stress, which is exactly what to be expected within the jamming picture. We propose a jamming phase diagram for polymers based on our laboratory experiments.

Spatiotemporal Self-Organization of Fluctuating Bacterial Colonies

NASA Astrophysics Data System (ADS)

Grafke, Tobias; Cates, Michael E.; Vanden-Eijnden, Eric

2017-11-01

We model an enclosed system of bacteria, whose motility-induced phase separation is coupled to slow population dynamics. Without noise, the system shows both static phase separation and a limit cycle, in which a rising global population causes a dense bacterial colony to form, which then declines by local cell death, before dispersing to reinitiate the cycle. Adding fluctuations, we find that static colonies are now metastable, moving between spatial locations via rare and strongly nonequilibrium pathways, whereas the limit cycle becomes almost periodic such that after each redispersion event the next colony forms in a random location. These results, which hint at some aspects of the biofilm-planktonic life cycle, can be explained by combining tools from large deviation theory with a bifurcation analysis in which the global population density plays the role of control parameter.

Applied optics. Multiwavelength achromatic metasurfaces by dispersive phase compensation.

PubMed

Aieta, Francesco; Kats, Mikhail A; Genevet, Patrice; Capasso, Federico

2015-03-20

The replacement of bulk refractive optical elements with diffractive planar components enables the miniaturization of optical systems. However, diffractive optics suffers from large chromatic aberrations due to the dispersion of the phase accumulated by light during propagation. We show that this limitation can be overcome with an engineered wavelength-dependent phase shift imparted by a metasurface, and we demonstrate a design that deflects three wavelengths by the same angle. A planar lens without chromatic aberrations at three wavelengths is also presented. Our designs are based on low-loss dielectric resonators, which introduce a dense spectrum of optical modes to enable dispersive phase compensation. The suppression of chromatic aberrations in metasurface-based planar photonics will find applications in lightweight collimators for displays, as well as chromatically corrected imaging systems. Copyright © 2015, American Association for the Advancement of Science.

Managing slash to minimize colonization of residual leave trees by Ips and other bark beetle species following thinning in southwestern ponderosa pine

Treesearch

T. DeGomez; C.J. Fettig; J.D. McMillin; J.A. Anhold; C.J. Hayes

2008-01-01

Due to high fire hazard and perceived reductions in forest health, thinning of small diameter trees has become a prevalent management activity particularly in dense stands. Creation of large amounts of logging slash, however, has created large quantities of habitat for bark beetles primarily in the Ips genus (Coleoptera: Curculionidae,...

Forests of the Oregon Coast Range-considerations for ecological restoration

Treesearch

Joe Means; Shu-hei Chen; Jane Kertis; Pete Teensma

1996-01-01

The Oregon Coast Range supports some of the most dense and productive forests in North America. In the pre-harvesting period these forests arose as a result of large fires-the largest covering 330,000 ha (Teensma and others 1991). These fires occurred mostly at intervals of 150 to 300 years. The natural disturbance regime supported a diverse fauna and large populations...

A Modular Localization System as a Positioning Service for Road Transport

PubMed Central

Brida, Peter; Machaj, Juraj; Benikovsky, Jozef

2014-01-01

In recent times smart devices have attracted a large number of users. Since many of these devices allow position estimation using Global Navigation Satellite Systems (GNSS) signals, a large number of location-based applications and services have emerged, especially in transport systems. However GNSS signals are affected by the environment and are not always present, especially in dense urban environment or indoors. In this work firstly a Modular Localization Algorithm is proposed to allow seamless switching between different positioning modules. This helps us develop a positioning system that is able to provide position estimates in both indoor and outdoor environments without any user interaction. Since the proposed system can run as a service on any smart device, it could allow users to navigate not only in outdoor environments, but also indoors, e.g., underground garages, tunnels etc. Secondly we present the proposal of a 2-phase map reduction algorithm which allows one to significantly reduce the complexity of position estimation processes in case that positioning is performed using a fingerprinting framework. The proposed 2-phase map reduction algorithm can also improve the accuracy of the position estimates by filtering out reference points that are far from the mobile device. Both algorithms were implemented into a positioning system and tested in real world conditions in both indoor and outdoor environments. PMID:25353979

Collisional excitation of molecules in dense interstellar clouds

NASA Technical Reports Server (NTRS)

Green, S.

1985-01-01

State transitions which permit the identification of the molecular species in dense interstellar clouds are reviewed, along with the techniques used to calculate the transition energies, the database on known molecular transitions and the accuracy of the values. The transition energies cannot be measured directly and therefore must be modeled analytically. Scattering theory is used to determine the intermolecular forces on the basis of quantum mechanics. The nuclear motions can also be modeled with classical mechanics. Sample rate constants are provided for molecular systems known to inhabit dense interstellar clouds. The values serve as a database for interpreting microwave and RF astrophysical data on the transitions undergone by interstellar molecules.

GPU computing with Kaczmarz’s and other iterative algorithms for linear systems

PubMed Central

Elble, Joseph M.; Sahinidis, Nikolaos V.; Vouzis, Panagiotis

2009-01-01

The graphics processing unit (GPU) is used to solve large linear systems derived from partial differential equations. The differential equations studied are strongly convection-dominated, of various sizes, and common to many fields, including computational fluid dynamics, heat transfer, and structural mechanics. The paper presents comparisons between GPU and CPU implementations of several well-known iterative methods, including Kaczmarz’s, Cimmino’s, component averaging, conjugate gradient normal residual (CGNR), symmetric successive overrelaxation-preconditioned conjugate gradient, and conjugate-gradient-accelerated component-averaged row projections (CARP-CG). Computations are preformed with dense as well as general banded systems. The results demonstrate that our GPU implementation outperforms CPU implementations of these algorithms, as well as previously studied parallel implementations on Linux clusters and shared memory systems. While the CGNR method had begun to fall out of favor for solving such problems, for the problems studied in this paper, the CGNR method implemented on the GPU performed better than the other methods, including a cluster implementation of the CARP-CG method. PMID:20526446

Dynamical Mass Segregation Versus Disruption of Binary Stars in Dense Stellar Systems

NASA Astrophysics Data System (ADS)

de Grijs, Richard; Li, C.; Deng, L.

2013-01-01

Upon their formation, dynamically cool (collapsing) star clusters will, within only a few million years, achieve stellar mass segregation for stars down to a few solar masses due to gravitational two-body encounters. Since binary systems are, on average, more massive than single stars, one would expect them to also rapidly mass segregate dynamically. Contrary to these expectations and based on high-resolution Hubble Space Telescope observations, we show that the compact, 15-30 Myr-old Large Magellanic Cloud cluster NGC 1818 is characterized by an increasing fraction of F-star binary systems (with combined masses of 1.3-1.6 solar masses) with increasing distance from the cluster center. This offers unprecedented support of the theoretically predicted but thus far unobserved dynamical disruption processes of the significant population of "soft" binary systems (with relatively low binding energies compared to the kinetic energy of their stellar members) in star clusters, which we could unravel by virtue of the cluster's unique combination of youth and high stellar density.

Assimilation of glider and mooring data into a coastal ocean model

NASA Astrophysics Data System (ADS)

Jones, Emlyn M.; Oke, Peter R.; Rizwi, Farhan; Murray, Lawrence M.

We have applied an ensemble optimal interpolation (EnOI) data assimilation system to a high resolution coastal ocean model of south-east Tasmania, Australia. The region is characterised by a complex coastline with water masses influenced by riverine input and the interaction between two offshore current systems. Using a large static ensemble to estimate the systems background error covariance, data from a coastal observing network of fixed moorings and a Slocum glider are assimilated into the model at daily intervals. We demonstrate that the EnOI algorithm can successfully correct a biased high resolution coastal model. In areas with dense observations, the assimilation scheme reduces the RMS difference between the model and independent GHRSST observations by 90%, while the domain-wide RMS difference is reduced by a more modest 40%. Our findings show that errors introduced by surface forcing and boundary conditions can be identified and reduced by a relatively sparse observing array using an inexpensive ensemble-based data assimilation system.

Pathogenesis of trimethyltin neuronal toxicity. Ultrastructural and cytochemical observations.

PubMed Central

Bouldin, T. W.; Goines, N. D.; Bagnell, R. C.; Krigman, M. R.

1981-01-01

The ultrastructural cytopathologic and cytochemical effects of trimethyltin (TMT) neurotoxicity were delineated in hippocampal and pyriform neurons of acutely intoxicated adult rats. TMT produced neuronal necrosis that preferentially involved hippocampal formation pyriform cortex. The first subcellular alterations were multifocal collection of dense-cored vesicles and tubules and membrane-delimited vacuoles in the cytoplasm of the perikaryon and proximal dendrite. Ultrastructural cytochemical examination revealed that the vesicles and tubules had acid phosphatase activity analagous to Golgi-associated endoplasmic reticulum (GERL). Shortly after the appearance of the GERL-like vesicles and tubules, autophagic vacuoles and polymorphic dense bodies accumulated in the neuronal cytoplasm. Some dense bodies appeared to arise from the dense-cored tubules. Neuronal necrosis was characterized by increased electron density of the cytoplasm and large, electron-dense intranuclear masses. Alterations of mitochondria and other organelles were not observed in the early stages of cell injury. No light- or electron-microscopic alterations were found in liver or kidney. Comparable subcellular alterations were observed in adult and neonatal rats chronically intoxicated with TMT. A series of other trialkyl and tricyclic tins and dimethyltin did not produce similar pathologic findings. The GERL-like accumulations are unique in neuronal cytopathology. These findings suggests that GERL and autophagy play an important role in the pathogenesis of TMT-induced neuronal injury. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 PMID:7294153

Structures of GMC W 37

NASA Astrophysics Data System (ADS)

Zhan, Xiao-Liang; Jiang, Zhi-Bo; Chen, Zhi-Wei; Zhang, Miao-Miao; Song, Chao

2016-04-01

We carried out observations toward the giant molecular cloud W 37 with the J = 1 - 0 transitions of 12CO, 13CO and C18O using the 13.7m single-dish telescope at the Delingha station of Purple Mountain Observatory. Based on these CO lines, we calculated the column densities and cloud masses for molecular clouds with radial velocities around +20 km s-1. The gas mass of W 37, calculated from 13 CO emission, is 1.7 × 105 M⊙, above the criterion to be considered a giant molecular cloud. The dense ridge of W 37 is a dense filament, which is supercritical in terms of linear mass ratio. Dense clumps found by C18O emission are aligned along the dense ridge at regular intervals of about 2.8 pc, similar to the clump separation caused by large-scale ‘sausage instability’. We confirm the identification of the giant molecular filament (GMF) G 18.0-16.8 and find a new giant filament, G 16.5-15.8, located ˜ 0.7° to the west of G 18.0-16.8. Both GMFs are not gravitationally bound, as indicated by their low linear mass ratio (˜ 80 M⊙ pc-1). We compared the gas temperature map with the dust temperature map from Herschel images, and found similar structures. The spatial distributions of class I objects and the dense clumps are reminiscent of triggered star formation occurring in the northwestern part of W 37, which is close to NGC 6611.

Developing Cost-Effective Dense Continuous SDC Barrier Layers for SOFCs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Hoang Viet P.; Hardy, John S.; Coyle, Christopher A.

Significantly improved performance during electrochemical testing of a cell with a dense continuous pulsed laser deposited (PLD) samarium doped ceria (SDC) layer spurred investigations into the fabrication of dense continuous SDC barrier layers by means of cost-effective deposition using screen printing which is amenable to industrial production of SOFCs. Many approaches to improve the SDC density have been explored including the use of powder with reduced particle sizes, inks with increased solids loading, and doping with sintering aids (1). In terms of sintering aids, dopants like Mo or binary systems of Mo+Cu or Fe+Co greatly enhance SDC sinterability. In fact,more » adding dopants to a screen printed, prefired, porous SDC layer made it possible to achieve a dense continuous barrier layer atop the YSZ electrolyte without sintering above 1200°C. Although the objective of fabricating a dense continuous layer was achieved, additional studies have been initiated to improve the cell performance. Underlying issues with constrained sintering and dopant-enhanced ceria-zirconia solid solubility are also addressed in this paper.« less

On the dense water spreading off the Ross Sea shelf (Southern Ocean)

NASA Astrophysics Data System (ADS)

Budillon, G.; Gremes Cordero, S.; Salusti, E.

2002-07-01

In this study, current meter and hydrological data obtained during the X Italian Expedition in the Ross Sea (CLIMA Project) are analyzed. Our data show a nice agreement with previous data referring to the water masses present in this area and their dynamics. Here, they are used to further analyze the mixing and deepening processes of Deep Ice Shelf Water (DISW) over the northern shelf break of the Ross Sea. In more detail, our work is focused on the elementary mechanisms that are the most efficient in removing dense water from the shelf: either classical mixing effects or density currents that interact with some topographic irregularity in order to drop to deeper levels, or also the variability of the Antarctic Circumpolar Current (ACC) which, in its meandering, can push the dense water off the shelf, thus interrupting its geostrophic flow. We also discuss in detail the (partial) evidence of dramatic interactions of the dense water with bottom particulate, of geological or biological origin, thus generating impulsive or quasi-steady density-turbidity currents. This complex interaction allows one to consider bottom particular and dense water as a unique self-interacting system. In synthesis, this is a first tentative analysis of the effect of bottom particulate on the dense water dynamics in the Ross Sea.

Sediment transport processes at the head of Halibut Canyon, Eastern Canada margin: An interplay between internal tides and dense shelf water cascading.

NASA Astrophysics Data System (ADS)

Puig, Pere; Greenan, Blair J. W.; Li, Michael Z.; Prescott, Robert H.; Piper, David J. W.

2013-04-01

To investigate the processes by which sediment is transported through a submarine canyon incised in a glaciated margin, the bottom boundary layer quadrapod RALPH was deployed at 276-m depth in the West Halibut Canyon (off Newfoundland) during winter 2008-2009. Two main sediment transport processes were identified throughout the deployment. Firstly, periodic increases of near-bottom suspended-sediment concentrations (SSC) were recorded associated with the up-canyon propagation of the semidiurnal internal tidal bore along the canyon axis, carrying fine sediment particles resuspended from deeper canyon regions. The recorded SSC peaks, lasting less than one hour, were observed sporadically and were linked to bottom intensified up-canyon flows concomitant with sharp drops in temperature. Secondly, sediment transport was also observed during events of intensified down-canyon current velocities that occurred during periods of sustained heat loss from surface waters, but were not associated with large storms. High-resolution velocity profiles throughout the water column during these events revealed that the highest current speeds (~1 m s-1) were centered several meters above the sea floor and corresponded to the region of maximum velocities of a gravity flow. Such flows had associated low SSC and cold water temperatures and have been interpreted as dense shelf water cascading events channelized along the canyon axis. Sediment transport during these events was largely restricted to bedload and saltation, producing winnowing of sands and fine sediments around larger gravel particles. Analysis of historical hydrographic data suggests that the origin of such gravity flows is not related to the formation of coastal dense waters advected towards the canyon head. Rather, the dense shelf waters appear to be generated around the outer shelf, where convection during winter is able to reach the sea floor and generate a pool of near-bottom dense water that cascades into the canyon during one or two tidal cycles. A similar transport mechanism can occur in other submarine canyons along the eastern Canadian margin, as well in other canyoned regions elsewhere, where winter convection generally reaches the shelf-edge.

Treatment of dystrophic calcification on a silicone intraocular lens with pars plana vitrectomy

PubMed Central

Mehta, Nitish; Goldberg, Roger A; Shah, Chirag P

2014-01-01

Purpose Dense, vision-obscuring calcification on the posterior aspect of silicone intraocular lenses (IOLs) is often not amenable to neodymium:yttrium-aluminum-garnet capsulotomy, and, in prior reports, has required IOL exchange. We report the successful removal of dense calcium deposition on the posterior surface of a three-piece silicone lens using pars plana vitrectomy (PPV). Materials and methods A 23-gauge PPV was performed using the Stellaris® vitrectomy system. A light pipe was used to retroilluminate the IOL, and a dense fibrous tissue setting with a low cut-rate and high aspiration rate was able to clear the visual axis of the dystrophic calcification without damaging the IOL optic. Results Visual acuity improved from 20/100 to 20/25. Conclusion Small-gauge PPV may be utilized to remove dense dystrophic calcium deposits on the lens surface in lieu of IOL exchange. PMID:25045246

Experimental Highlights: Heavy Quark Physics in Heavy-Ion Collisions at RHIC

DOE PAGES

Nouicer, Rachid

2017-03-22

The discovery at RHIC of large high-p T suppression and flow of electrons from heavy quarks flavors have altered our view of the hot and dense matter formed in central Au + Au collisions at √s NN = 200 GeV. These results suggest a large energy loss and flow of heavy quarks in the hot, dense matter. In recent years, the RHIC experiments upgraded the detectors; (1) PHENIX Collaboration installed silicon vertex tracker (VTX) at midrapidity region and forward silicon vertex tracker (FVTX) at the forward rapidity region, and (2) STAR Collaboration installed the heavy flavor tracker (HFT) and themore » muon telescope detector (MTD) both at the mid-rapidity region. The PHENIX experiments established measurements of ψ (1S ) and ψ (2S ) production as a function of system size, p + p, p + Al, p + Au, and 3He + Au collisions at √s NN = 200 GeV. In p/ 3He + A collisions at forward rapidity, we observe no difference in the ψ (2S )/ψ (1S ) ratio relative to p + p collisions. At backward rapidity, where the comoving particle density is higher, we find that the ψ (2S ) is preferentially suppressed by a factor of two. STAR Collaboration presents the first J/ ψ measurements in the di-muon decay channel in Au + Au at √s NN = 200 GeV at mid-rapidity. In conclusion, we observe a clear J/ψ R AA suppression and qualitatively well described by transport models, including dissociation and regeneration simultaneously.« less

The Formation and Gravitational-wave Detection of Massive Stellar Black Hole Binaries

NASA Astrophysics Data System (ADS)

Belczynski, Krzysztof; Buonanno, Alessandra; Cantiello, Matteo; Fryer, Chris L.; Holz, Daniel E.; Mandel, Ilya; Miller, M. Coleman; Walczak, Marek

2014-07-01

If binaries consisting of two ~100 M ⊙ black holes exist, they would serve as extraordinarily powerful gravitational-wave sources, detectable to redshifts of z ~ 2 with the advanced LIGO/Virgo ground-based detectors. Large uncertainties about the evolution of massive stars preclude definitive rate predictions for mergers of these massive black holes. We show that rates as high as hundreds of detections per year, or as low as no detections whatsoever, are both possible. It was thought that the only way to produce these massive binaries was via dynamical interactions in dense stellar systems. This view has been challenged by the recent discovery of several >~ 150 M ⊙ stars in the R136 region of the Large Magellanic Cloud. Current models predict that when stars of this mass leave the main sequence, their expansion is insufficient to allow common envelope evolution to efficiently reduce the orbital separation. The resulting black hole-black hole binary remains too wide to be able to coalesce within a Hubble time. If this assessment is correct, isolated very massive binaries do not evolve to be gravitational-wave sources. However, other formation channels exist. For example, the high multiplicity of massive stars, and their common formation in relatively dense stellar associations, opens up dynamical channels for massive black hole mergers (e.g., via Kozai cycles or repeated binary-single interactions). We identify key physical factors that shape the population of very massive black hole-black hole binaries. Advanced gravitational-wave detectors will provide important constraints on the formation and evolution of very massive stars.

A Spiking Neural Simulator Integrating Event-Driven and Time-Driven Computation Schemes Using Parallel CPU-GPU Co-Processing: A Case Study.

PubMed

Naveros, Francisco; Luque, Niceto R; Garrido, Jesús A; Carrillo, Richard R; Anguita, Mancia; Ros, Eduardo

2015-07-01

Time-driven simulation methods in traditional CPU architectures perform well and precisely when simulating small-scale spiking neural networks. Nevertheless, they still have drawbacks when simulating large-scale systems. Conversely, event-driven simulation methods in CPUs and time-driven simulation methods in graphic processing units (GPUs) can outperform CPU time-driven methods under certain conditions. With this performance improvement in mind, we have developed an event-and-time-driven spiking neural network simulator suitable for a hybrid CPU-GPU platform. Our neural simulator is able to efficiently simulate bio-inspired spiking neural networks consisting of different neural models, which can be distributed heterogeneously in both small layers and large layers or subsystems. For the sake of efficiency, the low-activity parts of the neural network can be simulated in CPU using event-driven methods while the high-activity subsystems can be simulated in either CPU (a few neurons) or GPU (thousands or millions of neurons) using time-driven methods. In this brief, we have undertaken a comparative study of these different simulation methods. For benchmarking the different simulation methods and platforms, we have used a cerebellar-inspired neural-network model consisting of a very dense granular layer and a Purkinje layer with a smaller number of cells (according to biological ratios). Thus, this cerebellar-like network includes a dense diverging neural layer (increasing the dimensionality of its internal representation and sparse coding) and a converging neural layer (integration) similar to many other biologically inspired and also artificial neural networks.

Building Ventilation as an Effective Disease Intervention Strategy in a Dense Indoor Contact Network in an Ideal City.

PubMed

Gao, Xiaolei; Wei, Jianjian; Lei, Hao; Xu, Pengcheng; Cowling, Benjamin J; Li, Yuguo

2016-01-01

Emerging diseases may spread rapidly through dense and large urban contact networks, especially they are transmitted by the airborne route, before new vaccines can be made available. Airborne diseases may spread rapidly as people visit different indoor environments and are in frequent contact with others. We constructed a simple indoor contact model for an ideal city with 7 million people and 3 million indoor spaces, and estimated the probability and duration of contact between any two individuals during one day. To do this, we used data from actual censuses, social behavior surveys, building surveys, and ventilation measurements in Hong Kong to define eight population groups and seven indoor location groups. Our indoor contact model was integrated with an existing epidemiological Susceptible, Exposed, Infectious, and Recovered (SEIR) model to estimate disease spread and with the Wells-Riley equation to calculate local infection risks, resulting in an integrated indoor transmission network model. This model was used to estimate the probability of an infected individual infecting others in the city and to study the disease transmission dynamics. We predicted the infection probability of each sub-population under different ventilation systems in each location type in the case of a hypothetical airborne disease outbreak, which is assumed to have the same natural history and infectiousness as smallpox. We compared the effectiveness of controlling ventilation in each location type with other intervention strategies. We conclude that increasing building ventilation rates using methods such as natural ventilation in classrooms, offices, and homes is a relatively effective strategy for airborne diseases in a large city.

First Results from the Dense Extragalactic GBT+ARGUS Survey (DEGAS): A Direct, Quantitative Test of the Role of Gas Density in Star Formation

NASA Astrophysics Data System (ADS)

Kepley, Amanda; Bigiel, Frank; Bolatto, Alberto; Church, Sarah; Cleary, Kieran; Frayer, David; Gallagher, Molly; Gundersen, Joshua; Harris, Andrew; Hughes, Annie; Jimenez-Donaire, Maria Jesus; Kessler, Sarah; Lee, Cheoljong; Leroy, Adam; Li, Jialu; Donovan Meyer, Jennifer; Rosolowsky, Erik; Sandstrom, Karin; Schinnener, Eva; Schruba, Andreas; Sieth, Matt; Usero, Antonio

2018-01-01

Gas density plays a central role in all modern theories of star formation. A key test of these theories involves quantifying the resolved gas density distribution and its relationship to star formation within a wide range of galactic environments. Until recently, this experiment has been difficult to perform owing to the faint nature of key molecular gas tracers like HCN and HCO+, but the superior sensitivity of modern millimeter instruments like ALMA and the IRAM 30m make these types of experiments feasible. In particular, the sensitivity and resolution provided by large aperture of the GBT combined with fast mapping speeds made possible by its new 16-pixel, 3mm focal plane array (Argus) make the GBT an almost-ideal instrument for this type of study. The Dense Extragalactic GBT+Argus Survey (DEGAS) will leverage these capabilities to perform the largest, resolved survey of molecular gas tracers in nearby galaxies, ultimately mapping a suite of four molecular gas tracers in the inner 2’ by 2’ of 36 nearby galaxies. When complete in 2020, DEGAS will be the largest resolved survey of dense molecular gas tracers in nearby galaxies. This talk will present early results from the first observations for this Green Bank Telescope large survey and highlight some exciting future possibilities for this survey.

Lock-and-key dimerization in dense Brownian systems of hard annular sector particles

NASA Astrophysics Data System (ADS)

Hodson, Wade D.; Mason, Thomas G.

2016-08-01

We develop a translational-rotational cage model that describes the behavior of dense two-dimensional (2D) Brownian systems of hard annular sector particles (ASPs), resembling C shapes. At high particle densities, pairs of ASPs can form mutually interdigitating lock-and-key dimers. This cage model considers either one or two mobile central ASPs which can translate and rotate within a static cage of surrounding ASPs that mimics the system's average local structure and density. By comparing with recent measurements made on dispersions of microscale lithographic ASPs [P. Y. Wang and T. G. Mason, J. Am. Chem. Soc. 137, 15308 (2015), 10.1021/jacs.5b10549], we show that mobile two-particle predictions of the probability of dimerization Pdimer, equilibrium constant K , and 2D osmotic pressure Π2 D as a function of the particle area fraction ϕA correspond closely to these experiments. By contrast, predictions based on only a single mobile particle do not agree well with either the two-particle predictions or the experimental data. Thus, we show that collective entropy can play an essential role in the behavior of dense Brownian systems composed of nontrivial hard shapes, such as ASPs.

Dispersion-optimized optical fiber for high-speed long-haul dense wavelength division multiplexing transmission

NASA Astrophysics Data System (ADS)

Wu, Jindong; Chen, Liuhua; Li, Qingguo; Wu, Wenwen; Sun, Keyuan; Wu, Xingkun

2011-07-01

Four non-zero-dispersion-shifted fibers with almost the same large effective area (Aeff) and optimized dispersion properties are realized by novel index profile designing and modified vapor axial deposition and modified chemical vapor deposition processes. An Aeff of greater than 71 μm2 is obtained for the designed fibers. Three of the developed fibers with positive dispersion are improved by reducing the 1550nm dispersion slope from 0.072ps/nm2/km to 0.063ps/nm2/km or 0.05ps/nm2/km, increasing the 1550nm dispersion from 4.972ps/nm/km to 5.679ps/nm/km or 7.776ps/nm/km, and shifting the zero-dispersion wavelength from 1500nm to 1450nm. One of these fibers is in good agreement with G655D and G.656 fibers simultaneously, and another one with G655E and G.656 fibers; both fibers are beneficial to high-bit long-haul dense wavelength division multiplexing systems over S-, C-, and L-bands. The fourth developed fiber with negative dispersion is also improved by reducing the 1550nm dispersion slope from 0.12ps/nm2/km to 0.085ps/nm2/km, increasing the 1550nm dispersion from -4ps/nm/km to -6.016ps/nm/km, providing facilities for a submarine transmission system. Experimental measurements indicate that the developed fibers all have excellent optical transmission and good macrobending and splice performances.

SIMULATING LOCAL DENSE AREAS USING PMMA TO ASSESS AUTOMATIC EXPOSURE CONTROL IN DIGITAL MAMMOGRAPHY.

PubMed

Bouwman, R W; Binst, J; Dance, D R; Young, K C; Broeders, M J M; den Heeten, G J; Veldkamp, W J H; Bosmans, H; van Engen, R E

2016-06-01

Current digital mammography (DM) X-ray systems are equipped with advanced automatic exposure control (AEC) systems, which determine the exposure factors depending on breast composition. In the supplement of the European guidelines for quality assurance in breast cancer screening and diagnosis, a phantom-based test is included to evaluate the AEC response to local dense areas in terms of signal-to-noise ratio (SNR). This study evaluates the proposed test in terms of SNR and dose for four DM systems. The glandular fraction represented by the local dense area was assessed by analytic calculations. It was found that the proposed test simulates adipose to fully glandular breast compositions in attenuation. The doses associated with the phantoms were found to match well with the patient dose distribution. In conclusion, after some small adaptations, the test is valuable for the assessment of the AEC performance in terms of both SNR and dose. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Dense crystalline packings of ellipsoids

NASA Astrophysics Data System (ADS)

Jin, Weiwei; Jiao, Yang; Liu, Lufeng; Yuan, Ye; Li, Shuixiang

2017-03-01

An ellipsoid, the simplest nonspherical shape, has been extensively used as a model for elongated building blocks for a wide spectrum of molecular, colloidal, and granular systems. Yet the densest packing of congruent hard ellipsoids, which is intimately related to the high-density phase of many condensed matter systems, is still an open problem. We discover an unusual family of dense crystalline packings of self-dual ellipsoids (ratios of the semiaxes α : √{α }:1 ), containing 24 particles with a quasi-square-triangular (SQ-TR) tiling arrangement in the fundamental cell. The associated packing density ϕ exceeds that of the densest known SM2 crystal [ A. Donev et al., Phys. Rev. Lett. 92, 255506 (2004), 10.1103/PhysRevLett.92.255506] for aspect ratios α in (1.365, 1.5625), attaining a maximal ϕ ≈0.758 06 ... at α = 93 /64 . We show that the SQ-TR phase derived from these dense packings is thermodynamically stable at high densities over the aforementioned α range and report a phase diagram for self-dual ellipsoids. The discovery of the SQ-TR crystal suggests organizing principles for nonspherical particles and self-assembly of colloidal systems.

Simulation of a Driven Dense Granular Gas

NASA Astrophysics Data System (ADS)

Bizon, Chris; Shattuck, M. D.; Swift, J. B.; Swinney, Harry L.

1998-11-01

Event driven particle simulations quantitatively reproduce the experimental results on vibrated granular layers, including the formation of standing wave patterns(C. Bizon, M.D. Shattuck, J.B. Swift, W.D. McCormick, and H.L. Swinney, Phys. Rev. Lett. 80), pp. 57-60 (1998). and secondary instabilities(J.R. deBruyn, C. Bizon, M.D. Shattuck, D. Goldman, J.B. Swift, and H.L. Swinney, Phys. Rev. Lett. 81) (1998), to appear. . In these simulations the velocity distributions are nearly Gaussian when scaled with the local fluctuational kinetic energy (granular temperature); this suggests that inelastic dense gas kinetic theory is applicable. We perform simulations of a two-dimensional granular gas that is homogeneously driven with fluctuating forces. We find that the equation of state differs from that of an elastic dense gas and that this difference is due to a change in the distribution of relative velocities at collisions. Granular thermal conductivity and viscosity are measured by allowing the fluctuating forces to have large scale spatial gradients.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Eun Seon; Ruminski, Anne M.; Aloni, Shaul

Interest in hydrogen fuel is growing for automotive applications; however, safe, dense, solid-state hydrogen storage remains a formidable scientific challenge. Metal hydrides offer ample storage capacity and do not require cryogens or exceedingly high pressures for operation. However, hydrides have largely been abandoned because of oxidative instability and sluggish kinetics. We report a new, environmentally stable hydrogen storage material constructed of Mg nanocrystals encapsulated by atomically thin and gas-selective reduced graphene oxide (rGO) sheets. This material, protected from oxygen and moisture by the rGO layers, exhibits exceptionally dense hydrogen storage (6.5 wt% and 0.105 kg H 2 per litre inmore » the total composite). As rGO is atomically thin, this approach minimizes inactive mass in the composite, while also providing a kinetic enhancement to hydrogen sorption performance. In conclusion, these multilaminates of rGO-Mg are able to deliver exceptionally dense hydrogen storage and provide a material platform for harnessing the attributes of sensitive nanomaterials in demanding environments.« less

Graphene oxide/metal nanocrystal multilaminates as the atomic limit for safe and selective hydrogen storage.

PubMed

Cho, Eun Seon; Ruminski, Anne M; Aloni, Shaul; Liu, Yi-Sheng; Guo, Jinghua; Urban, Jeffrey J

2016-02-23

Interest in hydrogen fuel is growing for automotive applications; however, safe, dense, solid-state hydrogen storage remains a formidable scientific challenge. Metal hydrides offer ample storage capacity and do not require cryogens or exceedingly high pressures for operation. However, hydrides have largely been abandoned because of oxidative instability and sluggish kinetics. We report a new, environmentally stable hydrogen storage material constructed of Mg nanocrystals encapsulated by atomically thin and gas-selective reduced graphene oxide (rGO) sheets. This material, protected from oxygen and moisture by the rGO layers, exhibits exceptionally dense hydrogen storage (6.5 wt% and 0.105 kg H2 per litre in the total composite). As rGO is atomically thin, this approach minimizes inactive mass in the composite, while also providing a kinetic enhancement to hydrogen sorption performance. These multilaminates of rGO-Mg are able to deliver exceptionally dense hydrogen storage and provide a material platform for harnessing the attributes of sensitive nanomaterials in demanding environments.

Guiding of relativistic electron beams in dense matter by laser-driven magnetostatic fields.

PubMed

Bailly-Grandvaux, M; Santos, J J; Bellei, C; Forestier-Colleoni, P; Fujioka, S; Giuffrida, L; Honrubia, J J; Batani, D; Bouillaud, R; Chevrot, M; Cross, J E; Crowston, R; Dorard, S; Dubois, J-L; Ehret, M; Gregori, G; Hulin, S; Kojima, S; Loyez, E; Marquès, J-R; Morace, A; Nicolaï, Ph; Roth, M; Sakata, S; Schaumann, G; Serres, F; Servel, J; Tikhonchuk, V T; Woolsey, N; Zhang, Z

2018-01-09

Intense lasers interacting with dense targets accelerate relativistic electron beams, which transport part of the laser energy into the target depth. However, the overall laser-to-target energy coupling efficiency is impaired by the large divergence of the electron beam, intrinsic to the laser-plasma interaction. Here we demonstrate that an efficient guiding of MeV electrons with about 30 MA current in solid matter is obtained by imposing a laser-driven longitudinal magnetostatic field of 600 T. In the magnetized conditions the transported energy density and the peak background electron temperature at the 60-μm-thick target's rear surface rise by about a factor of five, as unfolded from benchmarked simulations. Such an improvement of energy-density flux through dense matter paves the ground for advances in laser-driven intense sources of energetic particles and radiation, driving matter to extreme temperatures, reaching states relevant for planetary or stellar science as yet inaccessible at the laboratory scale and achieving high-gain laser-driven thermonuclear fusion.

Harvesting the Decay Energy of 26-Al to Drive Lightning Discharge and Chondrule Formation

NASA Astrophysics Data System (ADS)

Johansen, A.; Okuzumi, S.

2017-02-01

We demonstrate that positrons released in the decay of 26-Al cause large-scale charging of dense pebble regions. The charge separation is neutralized by lightning discharge and this can lead to the formation of chondrules.

Planetary Rings

NASA Astrophysics Data System (ADS)

Tiscareno, Matthew S.

Planetary rings are the only nearby astrophysical disks and the only disks that have been investigated by spacecraft (especially the Cassini spacecraft orbiting Saturn). Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 10- 7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close range and in real time in planetary rings.We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The A, B, and C rings of Saturn, plus the Cassini Division, comprise our solar system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are found both at Uranus (where they comprise the main rings entirely) and at Saturn (where they are embedded in the broad disk) and are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty rings, likely generated by embedded source bodies, are surprisingly found to sport azimuthally confined arcs at Neptune, Saturn, and Jupiter. Finally, every known ring system includes a substantial component of diffuse dusty rings.Planetary rings have shown themselves to be useful as detectors of planetary processes around them, including the planetary magnetic field and interplanetary impactors as well as the gravity of nearby perturbing moons. Experimental rings science has made great progress in recent decades, especially numerical simulations of self-gravity wakes and other processes but also laboratory investigations of coefficient of restitution and spectroscopic ground truth. The age of self-sustained ring systems is a matter of debate; formation scenarios are most plausible in the context of the early solar system, while signs of youthfulness indicate at least that rings have never been static phenomena.

Systematic detection of seismic events at Mount St. Helens with an ultra-dense array

NASA Astrophysics Data System (ADS)

Meng, X.; Hartog, J. R.; Schmandt, B.; Hotovec-Ellis, A. J.; Hansen, S. M.; Vidale, J. E.; Vanderplas, J.

2016-12-01

During the summer of 2014, an ultra-dense array of 900 geophones was deployed around the crater of Mount St. Helens and continuously operated for 15 days. This dataset provides us an unprecedented opportunity to systematically detect seismic events around an active volcano and study their underlying mechanisms. We use a waveform-based matched filter technique to detect seismic events from this dataset. Due to the large volume of continuous data ( 1 TB), we performed the detection on the GPU cluster Stampede (https://www.tacc.utexas.edu/systems/stampede). We build a suite of template events from three catalogs: 1) the standard Pacific Northwest Seismic Network (PNSN) catalog (45 events); 2) the catalog from Hansen&Schmandt (2015) obtained with a reverse-time imaging method (212 events); and 3) the catalog identified with a matched filter technique using the PNSN permanent stations (190 events). By searching for template matches in the ultra-dense array, we find 2237 events. We then calibrate precise relative magnitudes for template and detected events, using a principal component fit to measure waveform amplitude ratios. The magnitude of completeness and b-value of the detected catalog is -0.5 and 1.1, respectively. Our detected catalog shows several intensive swarms, which are likely driven by fluid pressure transients in conduits or slip transients on faults underneath the volcano. We are currently relocating the detected catalog with HypoDD and measuring the seismic velocity changes at Mount St. Helens using the coda wave interferometry of detected repeating earthquakes. The accurate temporal-spatial migration pattern of seismicity and seismic property changes should shed light on the physical processes beneath Mount St. Helens.

A nutrient-dense, high-fiber, fruit-based supplement bar increases HDL cholesterol, particularly large HDL, lowers homocysteine, and raises glutathione in a 2-wk trial

PubMed Central

Mietus-Snyder, Michele L.; Shigenaga, Mark K.; Suh, Jung H.; Shenvi, Swapna V.; Lal, Ashutosh; McHugh, Tara; Olson, Don; Lilienstein, Joshua; Krauss, Ronald M.; Gildengoren, Ginny; McCann, Joyce C.; Ames, Bruce N.

2012-01-01

Dietary intake modulates disease risk, but little is known how components within food mixtures affect pathophysiology. A low-calorie, high-fiber, fruit-based nutrient-dense bar of defined composition (e.g., vitamins and minerals, fruit polyphenolics, β-glucan, docosahexaenoic acid) appropriate for deconstruction and mechanistic studies is described and evaluated in a pilot trial. The bar was developed in collaboration with the U.S. Department of Agriculture. Changes in cardiovascular disease and diabetes risk biomarkers were measured after 2 wk twice-daily consumption of the bar, and compared against baseline controls in 25 healthy adults. Plasma HDL-cholesterol (HDL-c) increased 6.2% (P=0.001), due primarily to a 28% increase in large HDL (HDL-L; P<0.0001). Total plasma homocysteine (Hcy) decreased 19% (P=0.017), and glutathione (GSH) increased 20% (P=0.011). The changes in HDL and Hcy are in the direction associated with decreased risk of cardiovascular disease and cognitive decline; increased GSH reflects improved antioxidant defense. Changes in biomarkers linked to insulin resistance and inflammation were not observed. A defined food-based supplement can, within 2 wk, positively impact metabolic biomarkers linked to disease risk. These results lay the groundwork for mechanistic/deconstruction experiments to identify critical bar components and putative synergistic combinations responsible for observed effects.—Mietus-Snyder, M. L., Shigenaga, M. K., Suh, J. H., Shenvi, S. V., Lal, A., McHugh, T., Olson, D., Lilienstein, J., Krauss, R. M., Gildengoren, G., McCann, J. C., Ames, B. N. A nutrient-dense, high-fiber, fruit-based supplement bar increases HDL cholesterol, particularly large HDL, lowers homocysteine, and raises glutathione in a 2-wk trial. PMID:22549511

From Interstellar Polycyclic Aromatic Hydrocarbons and Ice to the Origin of Life

NASA Technical Reports Server (NTRS)

Allamandola, Louis

2004-01-01

Tremendous strides have been made in our understanding of interstellar material over the past twenty years thanks to significant, parallel developments in observational astronomy and laboratory astrophysics. Twenty years ago the composition of interstellar dust was largely guessed at, the concept of ices in dense molecular clouds ignored, and the notion of large, abundant, gas phase, carbon rich molecules widespread throughout the interstellar medium (ISM) considered impossible. Today the composition of dust in the diffuse ISM is reasonably well constrained to cold refractory materials comprised of amorphous and crystalline silicates mixed with an amorphous carbonaceous material containing aromatic structural units and short, branched aliphatic chains. In the dense ISM, the birthplace of stars and planets, these cold dust particles are coated with mixed molecular ices whose composition is very well constrained. Lastly, the signature of carbon-rich polycyclic aromatic hydrocarbons (PAHs), shockingly large molecules by early interstellar chemistry standards, is widespread throughout the Universe. The first part of this talk will describe how infrared studies of interstellar space, combined with laboratory simulations, have revealed the composition of interstellar ices (the building blocks of comets) and the high abundance and nature of interstellar PAHs. The laboratory database has now enabled us to gain insight into the identities, abundances, and physical state of many interstellar materials. Within a dense molecular cloud, and especially in the presolar nebula, the materials frozen into the interstellar/precometary ices are photoprocessed by ultraviolet light and produce more complex molecules. The remainder of the presentation will focus on the photochemical evolution of these materials and the possible role of these compounds on the to the carbonaceous components of micrometeorites, they are likely to have been important sources of complex materials on the early Earth and their composition may be related to the origin of life.

Mesons from Laser-Induced Processes in Ultra-Dense Hydrogen H(0)

PubMed Central

2017-01-01

Large signals of charged light mesons are observed in the laser-induced particle flux from ultra-dense hydrogen H(0) layers. The mesons are formed in such layers on metal surfaces using < 200 mJ laser pulse-energy. The time variation of the signal to metal foil collectors and the magnetic deflection to a movable pin collector are now studied. Relativistic charged particles with velocity up to 500 MeV u-1 thus 0.75 c are observed. Characteristic decay time constants for meson decay are observed, for charged and neutral kaons and also for charged pions. Magnetic deflections agree with charged pions and kaons. Theoretical predictions of the decay chains from kaons to muons in the particle beam agree with the results. Muons are detected separately by standard scintillation detectors in laser-induced processes in ultra-dense hydrogen H(0) as published previously. The muons formed do not decay appreciably within the flight distances used here. Most of the laser-ejected particle flux with MeV energy is not deflected by the magnetic fields and is thus neutral, either being neutral kaons or the ultra-dense HN(0) precursor clusters. Photons give only a minor part of the detected signals. PACS: 67.63.Gh, 14.40.-n, 79.20.Ds, 52.57.-z. PMID:28081199

STAR FORMATION RELATIONS IN THE MILKY WAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vutisalchavakul, Nalin; Evans II, Neal J.; Heyer, Mark, E-mail: nje@astro.as.utexas.edu

2016-11-01

The relations between star formation and properties of molecular clouds (MCs) are studied based on a sample of star-forming regions in the Galactic Plane. Sources were selected by having radio recombination lines to provide identification of associated MCs and dense clumps. Radio continuum emission and mid-infrared emission were used to determine star formation rates (SFRs), while {sup 13}CO and submillimeter dust continuum emission were used to obtain the masses of molecular and dense gas, respectively. We test whether total molecular gas or dense gas provides the best predictor of SFR. We also test two specific theoretical models, one relying onmore » the molecular mass divided by the free-fall time, the other using the free-fall time divided by the crossing time. Neither is supported by the data. The data are also compared to those from nearby star-forming regions and extragalactic data. The star formation “efficiency,” defined as SFR divided by mass, spreads over a large range when the mass refers to molecular gas; the standard deviation of the log of the efficiency decreases by a factor of three when the mass of relatively dense molecular gas is used rather than the mass of all of the molecular gas.« less

Classical and quantum simulations of warm dense carbon

NASA Astrophysics Data System (ADS)

Whitley, Heather; Sanchez, David; Hamel, Sebastien; Correa, Alfredo; Benedict, Lorin

We have applied classical and DFT-based molecular dynamics (MD) simulations to study the equation of state of carbon in the warm dense matter regime (ρ = 3.7 g/cc, 0.86 eV

Mesoscopic coherence in light scattering from cold, optically dense and disordered atomic systems

NASA Astrophysics Data System (ADS)

Kupriyanov, D. V.; Sokolov, I. M.; Havey, M. D.

2017-02-01

Coherent effects manifested in light scattering from cold, optically dense and disordered atomic systems are reviewed from a primarily theoretical point of view. Development of the basic theoretical tools is then elaborated through several physical atomic physics based processes which have been at least partly explored experimentally. These include illustrations drawn from the coherent backscattering effect, random lasing in atomic gases, quantum memories and light-atoms interface assisted by the light trapping mechanism. Current understanding and challenges associated with the transition to high atomic densities and cooperativity in the scattering process are also discussed in some detail.

Glassy dynamics of dense particle assemblies on a spherical substrate.

PubMed

Vest, Julien-Piera; Tarjus, Gilles; Viot, Pascal

2018-04-28

We study by molecular dynamics simulation a dense one-component system of particles confined on a spherical substrate. We more specifically investigate the evolution of the structural and dynamical properties of the system when changing the control parameters, the temperature and the curvature of the substrate. We find that the dynamics become glassy at low temperature, with a strong slowdown of the relaxation and the emergence of dynamical heterogeneity. The prevalent local 6-fold order is frustrated by curvature and we analyze in detail the role of the topological defects in the statics and the dynamics of the particle assembly.

Dependence of the clustering properties of galaxies on stellar velocity dispersion in the Main galaxy sample of SDSS DR10

NASA Astrophysics Data System (ADS)

Deng, Xin-Fa; Song, Jun; Chen, Yi-Qing; Jiang, Peng; Ding, Ying-Ping

2014-08-01

Using two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 10 (SDSS DR10), we investigate the dependence of the clustering properties of galaxies on stellar velocity dispersion by cluster analysis. It is found that in the luminous volume-limited Main galaxy sample, except at r=1.2, richer and larger systems can be more easily formed in the large stellar velocity dispersion subsample, while in the faint volume-limited Main galaxy sample, at r≥0.9, an opposite trend is observed. According to statistical analyses of the multiplicity functions, we conclude in two volume-limited Main galaxy samples: small stellar velocity dispersion galaxies preferentially form isolated galaxies, close pairs and small group, while large stellar velocity dispersion galaxies preferentially inhabit the dense groups and clusters. However, we note the difference between two volume-limited Main galaxy samples: in the faint volume-limited Main galaxy sample, at r≥0.9, the small stellar velocity dispersion subsample has a higher proportion of galaxies in superclusters ( n≥200) than the large stellar velocity dispersion subsample.

A large-sized bubbling appearance of the glomerular basement membrane in a patient with pulmonary limited AL amyloidosis and a past history of lupus nephritis.

PubMed

Suga, Norihiro; Miura, Naoto; Uemura, Yuko; Nakamura, Toshinobu; Morita, Hiroyuki; Banno, Shogo; Imai, Hirokazu

2011-12-01

We report an unusual pathological finding, a large-sized bubbling appearance of the glomerular basement membrane (GBM), in a patient with pulmonary limited AL amyloidosis and a past history of lupus nephritis. The first renal biopsy specimen from 10 years ago, when systemic lupus erythematosus was diagnosed, demonstrated mild mesangial proliferation and subepithelial deposits (WHO classification: III + V). Light microscopy of the current biopsy using periodic acid methenamine silver (PAMS) stain demonstrated a large-sized bubbling appearance of the GBM; however, very weak immunoglobulin and complement deposition was observed in immunofluorescence studies. Routine electron microscopy demonstrated partial subendothelial expansion with electron-lucent materials, but no electron-dense deposits or amyloid fibrils. Electron microscopy with PAMS stain revealed electron-lucent endothelial scalloping, including some cellular components and microspheres in the GBM; however, it is not clear if these materials are derived from endothelial cells. One possibility is that these unique findings represent a recovery phase of lupus membranous nephritis; another is that these findings correspond to a new disease entity.

Containerless glass fiber processing

NASA Technical Reports Server (NTRS)

Ethridge, E. C.; Naumann, R. J.

1986-01-01

An acoustic levitation furnace system is described that was developed for testing the feasibility of containerless fiber pulling experiments. It is possible to levitate very dense materials such as platinum at room temperature. Levitation at elevated temperatures is much more difficult. Samples of dense heavy metal fluoride glass were levitated at 300 C. It is therefore possible that containerless fiber pulling experiments could be performed. Fiber pulling from the melt at 650 C is not possible at unit gravity but could be possible at reduced gravities. The Acoustic Levitation Furnace is described, including engineering parameters and processing information. It is illustrated that a shaped reflector greatly increases the levitation force aiding the levitation of more dense materials.

The Inner Structure of OH Megamaser Galaxies: The Genesis of the Unified Scheme of Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Axon, David

OH megamaser galaxies (OHMG) represent a key post-merger phase in the evolution of the Ultra-Luminous Infrared Galaxies (ULIRGs) population, in which an edge-on circum-nuclear gas disk (proto-torus) has already formed. Detailed interferometric mapping of maser sources implies that they originate in dense edge-on rotating molecular gas within a few tens of parsecs of the AGN. In addition, the OH lines are often broad (Doppler widths ~ 1000 km/s), implying large dynamical masses in the central few parsecs. In many systems the OH lines also show high velocity asymmetric tails suggesting large-scale outflows that could be clearing away enshrouding dense molecular material. Taken together this evidence points to a picture in which an OHMG hosts a nascent QSO surrounded by a flattened distribution of dense molecular gas that is in the process of being cleared away along the rotation axis of the maser disk. A great advantage of studying OHMG systems over the general ULIRG population is that the circum-nuclear disks are effectively "fixed" at an edge on orientation, thereby breaking the degeneracy between the number of clumps and inclination in state of the art clumpy torus models. We have been awarded HST time in cycle 17 to conduct a comprehensive study of structure of the circum-nuclear gas, and its relationship to the radio structure and that of the maser disk, of large sample (80) of OHMG. This work is supported by ground-based spectropolarimetry, integral field spectroscopy and new radio continuum observations, Our overall objective is to probe the final stages of evolution immediately before the full- emergence of an enshrouded AGN as the circum-nuclear dust is dispersed by starburst and AGN-induced outflows. The specific scientific goals of this ADP proposal are to retrieve and analyze the Spitzer thermal-IR 5-70 micron imaging and IRS spectra of the subset of 72 of our targets for which Spitzer observations are available in the archive. We aim to establish the relationship between host and circum-nuclear ionized gas and dust structures in different OHMG spectroscopic types (AGN, Starburst, Composite) and model the AGN and starburst contributions to the mid-IR SED. Combining these with our other data we will address a number of important questions: is the mid-IR SED consistent with an edge-on circum-nuclear dust structure, as expected from the maser observations? What is the relative orientation of the Maser molecular structure and the ionized gas? Is there a connection between AGN heating of the circum-nuclear dust and wind or radiation driven outflows from the nucleus? How does the bolometric luminosity of the AGN relate to the OH line luminosity, FWHM and line shape? In turn these will relate the ionizing luminosity to the covering factor of the torus and the enclosed dynamical mass. When complete, this study should provide new insights on the relationships between the fundamental physical parameters of the AGN, including black hole mass, accretion and mass outflow rates, and the large scale properties of the host galaxy.

Proteomics of Dense Core Secretory Vesicles Reveal Distinct Protein Categories for Secretion of Neuroeffectors for Cell-Cell Communication

PubMed Central

Wegrzyn, Jill L.; Bark, Steven J.; Funkelstein, Lydiane; Mosier, Charles; Yap, Angel; Kazemi-Esfarjani, Parasa; La Spada, Albert; Sigurdson, Christina; O’Connor, Daniel T.; Hook, Vivian

2010-01-01

Regulated secretion of neurotransmitters and neurohumoural factors from dense core secretory vesicles provides essential neuroeffectors for cell-cell communication in the nervous and endocrine systems. This study provides comprehensive proteomic characterization of the categories of proteins in chromaffin dense core secretory vesicles that participate in cell-cell communication from the adrenal medulla. Proteomic studies were conducted by nano-HPLC Chip MS/MS tandem mass spectrometry. Results demonstrate that these secretory vesicles contain proteins of distinct functional categories consisting of neuropeptides and neurohumoural factors, protease systems, neurotransmitter enzymes and transporters, receptors, enzymes for biochemical processes, reduction/oxidation regulation, ATPases, protein folding, lipid biochemistry, signal transduction, exocytosis, calcium regulation, as well as structural and cell adhesion proteins. The secretory vesicle proteomic data identified 371 distinct proteins in the soluble fraction and 384 distinct membrane proteins, for a total of 686 distinct secretory vesicle proteins. Notably, these proteomic analyses illustrate the presence of several neurological disease-related proteins in these secretory vesicles, including huntingtin interacting protein, cystatin C, ataxin 7, and prion protein. Overall, these findings demonstrate that multiple protein categories participate in dense core secretory vesicles for production, storage, and secretion of bioactive neuroeffectors for cell-cell communication in health and disease. PMID:20695487

The composition and metabolism of large and small LDL

USDA-ARS?s Scientific Manuscript database

Decreased size and increased density of LDL have been associated with increased coronary heart disease (CHD) risk. Elevated plasma concentrations of small dense LDL (sdLDL) correlate with high plasma triglycerides and low HDL cholesterol levels. This review highlights recent findings about the met...

Effects of Imazapic on Target and Nontarget Vegetation During Revegetation

USDA-ARS?s Scientific Manuscript database

Medusahead is an introduced, winter-annual grass covering millions of acres of western rangelands. It forms large monocultures and has a dense thatch cover that resists the establishment of desirable vegetation. Prescribed fire can remove medusahead litter and improve plant establishment. Medusah...

Water Masses in the Eastern Mediterranean Sea: An Analysis of Measured Isotopic Oxygen

NASA Astrophysics Data System (ADS)

de Ruggiero, Paola; Zanchettin, Davide; Bensi, Manuel; Hainbucher, Dagmar; Stenni, Barbara; Pierini, Stefano; Rubino, Angelo

2018-04-01

We investigate aspects of the water mass structure of the Adriatic and Ionian basins (Eastern Mediterranean Sea) and their interdecadal variability through statistical analyses focused on δ18Ο measurements carried out in 1985, 1990, and 2011. In particular, the more recent δ18Ο measurements extend throughout the entire water column and constitute, to the best of our knowledge, the largest synoptic dataset encompassing different sub-basins of the Mediterranean Sea. We study the statistical linkages between temperature, salinity, dissolved oxygen and δ18Ο. We find that δ18Ο is largely independent from the other parameters, and it can be used to trace major water masses that are typically found in the basins, including the Adriatic Dense Water, the Levantine Intermediate Water, and the Cretan Intermediate and Dense Waters. Finally, we explore the possibility of using δ18Ο concentration as a proxy for dominant modes of large-scale oceanic variability in the Mediterranean Sea.

The molecular composition of dense interstellar clouds

NASA Technical Reports Server (NTRS)

Allen, M.; Robinson, G. W.

1977-01-01

Presented in this paper is an ab initio chemical model for dense interstellar clouds that incorporates 598 grain surface reactions, with small grains providing the reaction area. Gas-phase molecules are depleted through collisions with grains. The abundances of 372 chemical species are calculated as a function of time and are found to be of sufficient magnitude to explain most observations. Peak abundances are achieved on time scales of the order of 100,000 to 1 million years, depending on cloud density and kinetic temperature. The reaction rates for ion-molecule chemistry are approximately the same, indicating that surface and gas-phase chemistry may be coupled in certain regions. The composition of grain mantles is shown to be a function of grain radius. In certain grain-size ranges, large molecules containing two or more heavy atoms are more predominant than lighter 'ices' - H2O, NH3, and CH4. It is possible that absorption due to these large molecules in the mantle may contribute to the observed 3-micron band in astronomical spectra.

Probing axions with neutron star inspirals and other stellar processes

NASA Astrophysics Data System (ADS)

Hook, Anson; Huang, Junwu

2018-06-01

In certain models of a QCD axion, finite density corrections to the axion potential can result in the axion being sourced by large dense objects. There are a variety of ways to test this phenomenon, but perhaps the most surprising effect is that the axion can mediate forces between neutron stars that can be as strong as gravity. These forces can be attractive or repulsive and their presence can be detected by Advanced LIGO observations of neutron star inspirals. By a numerical coincidence, axion forces between neutron stars with gravitational strength naturally have an associated length scale of tens of kilometers or longer, similar to that of a neutron star. Future observations of neutron star mergers in Advanced LIGO can probe many orders of magnitude of axion parameter space. Because the axion is only sourced by large dense objects, the axion force evades fifth force constraints. We also outline several other ways to probe this phenomenon using electromagnetic signals associated with compact objects.

Detecting axion stars with radio telescopes

NASA Astrophysics Data System (ADS)

Bai, Yang; Hamada, Yuta

2018-06-01

When axion stars fly through an astrophysical magnetic background, the axion-to-photon conversion may generate a large electromagnetic radiation power. After including the interference effects of the spacially-extended axion-star source and the macroscopic medium effects, we estimate the radiation power when an axion star meets a neutron star. For a dense axion star with 10-13M⊙, the radiated power is at the order of 1011W ×(100 μeV /ma) 4(B /1010Gauss) 2 with ma as the axion particle mass and B the strength of the neutron star magnetic field. For axion stars occupy a large fraction of dark matter energy density, this encounter event with a transient O (0.1s) radio signal may happen in our galaxy with the averaged source distance of one kiloparsec. The predicted spectral flux density is at the order of μJy for a neutron star with B ∼1013 Gauss. The existing Arecibo, GBT, JVLA and FAST and the ongoing SKA radio telescopes have excellent discovery potential of dense axion stars.

Biggest Radio-Telescope in Northern Europe, the RT-32 in Latvia

NASA Astrophysics Data System (ADS)

Monstein, Christian

2014-08-01

Hidden in the dense coastal forests of Slítere a mysterious ex-Soviet spy center is now used for science. Almost everyone including me who entered the site of the two large radio telescopes called Irbene, are amazed by the surrealistic atmosphere of the abandoned ghost town and two large radio dish antennas in the middle of nowhere. This article will tell more about this site; see also [1]. As the Cold War between the US and USSR entered the space age, the need for Space espionage led to the Soviets designing ways to track and decode signals from US satellites. The project began in 1967 when the remote areas of the Ventspils district were allocated for secret buildup of a site codenamed "Starlet". The location was chosen because of low population and dense forest areas of Slí;tere that also were part of the Soviet border zone - ensuring that no strangers could ever discover it.

Generation and characterisation of warm dense matter with intense lasers

NASA Astrophysics Data System (ADS)

Riley, D.

2018-01-01

In this paper I discuss the subject of warm dense matter (WDM), which, apart from being of academic interest and relevant to inertial fusion capsules, is a subject of importance to those who wish to understand the formation and structure of planetary interiors and other astrophysical bodies. I broadly outline some key properties of WDM and go on to discuss various methods of generating samples in the laboratory using large laser facilities and outline some common techniques of diagnosis. It is not intended as a comprehensive review but rather a brief outline for scientists new to the field and those with an interest but not working in the field directly.

Equations of state for neutron stars and core-collapse supernovae

NASA Astrophysics Data System (ADS)

Oertel, Micaela; Providência, Constança

2018-04-01

Modelling compact stars is a complex task which depends on many ingredients, among others the properties of dense matter. In this contribution models for the equation of state (EoS) of dense matter will be discussed, relevant for the description of core-collapse supernovae, compact stars and compact star mergers. Such EoS models have to cover large ranges in baryon number density, temperature and isospin asymmetry. The characteristics of matter change dramatically within these ranges, from a mixture of nucleons, nuclei, and electrons to uniform, strongly interacting matter containing nucleons, and possibly other particles such as hyperons or quarks. Some implications for compact star astrophysics will be highlighted, too.

Characterization of Localized Filament Corrosion Products at the Anodic Head on a Model Mg-Zn-Zr Alloy Surface

DOE PAGES

Rossouw, David; Fu, Dong; Leonard, Donovan N.; ...

2017-02-15

In this study, localized filament corrosion products at the anodic head on a model Mg-1%Zn-0.4%Zr alloy surface were characterized by electron microscopy techniques of site-specific lamella prepared by focused ion beam milling. It is revealed that the anodic head propagates underneath a largely intact thin and dense MgO surface film and comprises dense aggregates of nano-crystalline MgO within a nano-porous Mg(OH) 2 network. In conclusion, the findings contribute new supportive direct imaging insight into the source of the enhanced H 2 evolution that accompanies anodic dissolution of Mg and its alloys.

Conventional Radiology in Crystal Arthritis: Gout, Calcium Pyrophosphate Deposition, and Basic Calcium Phosphate Crystals.

PubMed

Jacques, Thibaut; Michelin, Paul; Badr, Sammy; Nasuto, Michelangelo; Lefebvre, Guillaume; Larkman, Neal; Cotten, Anne

2017-09-01

This article reviews the main radiographic features of crystal deposition diseases. Gout is linked to monosodium urate crystals. Classic radiographic features include subcutaneous tophi, large and well-circumscribed paraarticular bone erosions, and exuberant bone hyperostosis. Calcium pyrophosphate deposition (CPPD) can involve numerous structures, such as hyaline cartilages, fibrocartilages, or tendons. CPPD arthropathy involves joints usually spared by osteoarthritis. Basic calcium phosphate deposits are periarticular or intraarticular. Periarticular calcifications are amorphous, dense, and round or oval with well-limited borders, and most are asymptomatic. When resorbing, they become cloudy and less dense with an ill-defined shape and can migrate into adjacent structures. Copyright © 2017 Elsevier Inc. All rights reserved.

Characterization of Localized Filament Corrosion Products at the Anodic Head on a Model Mg-Zn-Zr Alloy Surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rossouw, David; Fu, Dong; Leonard, Donovan N.

In this study, localized filament corrosion products at the anodic head on a model Mg-1%Zn-0.4%Zr alloy surface were characterized by electron microscopy techniques of site-specific lamella prepared by focused ion beam milling. It is revealed that the anodic head propagates underneath a largely intact thin and dense MgO surface film and comprises dense aggregates of nano-crystalline MgO within a nano-porous Mg(OH) 2 network. In conclusion, the findings contribute new supportive direct imaging insight into the source of the enhanced H 2 evolution that accompanies anodic dissolution of Mg and its alloys.

Automatic Building Abstraction from Aerial Photogrammetry

NASA Astrophysics Data System (ADS)

Ley, A.; Hänsch, R.; Hellwich, O.

2017-09-01

Multi-view stereo has been shown to be a viable tool for the creation of realistic 3D city models. Nevertheless, it still states significant challenges since it results in dense, but noisy and incomplete point clouds when applied to aerial images. 3D city modelling usually requires a different representation of the 3D scene than these point clouds. This paper applies a fully-automatic pipeline to generate a simplified mesh from a given dense point cloud. The mesh provides a certain level of abstraction as it only consists of relatively large planar and textured surfaces. Thus, it is possible to remove noise, outlier, as well as clutter, while maintaining a high level of accuracy.

Fast, Dense Low Cost Scintillator for Nuclear Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woody, Craig

2009-07-31

We have studied the morphology, transparency, and optical properties of SrHfO{sub 3}:Ce ceramics. Ceramics can be made transparent by carefully controlling the stoichiometry of the precursor powders. When fully dense, transparent samples can be obtained. Ceramics with a composition close to stoichiometry (Sr:Hf ~ 1) appear to show good transparency and a reasonable light yield several times that of BGO. The contact and distance transparency of ceramics hot-pressed at about 1450ºC is very good, but deteriorates at increasingly higher hot-press temperatures. If these ceramics can be produced in large quantities and sizes, at low cost, they may be of considerablemore » interest for PET and CT.« less

Vision guided landing of an an autonomous helicopter in hazardous terrain

NASA Technical Reports Server (NTRS)

Johnson, Andrew E.; Montgomery, Jim

2005-01-01

Future robotic space missions will employ a precision soft-landing capability that will enable exploration of previously inaccessible sites that have strong scientific significance. To enable this capability, a fully autonomous onboard system that identifies and avoids hazardous features such as steep slopes and large rocks is required. Such a system will also provide greater functionality in unstructured terrain to unmanned aerial vehicles. This paper describes an algorithm for landing hazard avoidance based on images from a single moving camera. The core of the algorithm is an efficient application of structure from motion to generate a dense elevation map of the landing area. Hazards are then detected in this map and a safe landing site is selected. The algorithm has been implemented on an autonomous helicopter testbed and demonstrated four times resulting in the first autonomous landing of an unmanned helicopter in unknown and hazardous terrain.

A Large Number of Sprites from an Isolated Storm System in January in South West FL

NASA Astrophysics Data System (ADS)

Watanabe, K.; Atkins, C.; Chagnon, H.; Alaniz, S.; Sakamoto, T.; Okajima, T.; Hata, Y.; Yokosuga, F.; Yamamoto, A.

2017-12-01

Goddard Robotic Telescope - Wide Field (GRT-WF) was built in June 2011 as a sister instrument of GRT which is located at NASA Goddard Space Flight Center, Greenbelt, MD. GRT-WF utilizes seven wide field optical cameras located at Florida Gulf Coast University (FGCU) in Fort Myers, FL, to observe sprites in all the directions of the sky. Our primary goal is to study possible associations of sprites with TGFs (Terrestrial Gamma-ray Flashes), and we have detected 700 sprites so far. In this presentation, however, we report unique sprite events which occurred in January 2012. Although we hardly have thunderstorms in January in South West FL, we detected 70 sprites from an isolated storm system traveling in the Gulf of Mexico region over a single night. This is the first time we observed such dense sprite events. We will report the detailed properties of these sprites.

Dynamical patterns in nematic active matter on a sphere

NASA Astrophysics Data System (ADS)

Henkes, Silke; Marchetti, M. Cristina; Sknepnek, Rastko

2018-04-01

Using simulations of self-propelled agents with short-range repulsion and nematic alignment, we explore the dynamical phases of a dense active nematic confined to the surface of a sphere. We map the nonequilibrium phase diagram as a function of curvature, alignment strength, and activity. Our model reproduces several phases seen in recent experiments on active microtubule bundles confined the surfaces of vesicles. At low driving, we recover the equilibrium nematic ground state with four +1 /2 defects. As the driving is increased, geodesic forces drive the transition to a polar band wrapping around an equator, with large empty spherical caps corresponding to two +1 defects at the poles. Upon further increasing activity, the bands fold onto themselves, and the system eventually transitions to a turbulent state marked by the proliferation of pairs of topological defects. We highlight the key role of the nematic persistence length in controlling pattern formation in these confined systems with positive Gaussian curvature.

Spectral classification with the International Ultraviolet Explorer: An atlas of B-type spectra

NASA Technical Reports Server (NTRS)

Rountree, Janet; Sonneborn, George

1993-01-01

New criteria for the spectral classification of B stars in the ultraviolet show that photospheric absorption lines in the 1200-1900A wavelength region can be used to classify the spectra of B-type dwarfs, subgiants, and giants on a 2-D system consistent with the optical MK system. This atlas illustrates a large number of such spectra at the scale used for classification. These spectra provide a dense matrix of standard stars, and also show the effects of rapid stellar rotation and stellar winds on the spectra and their classification. The observational material consists of high-dispersion spectra from the International Ultraviolet Explorer archives, resampled to a resolution of 0.25 A, uniformly normalized, and plotted at 10 A/cm. The atlas should be useful for the classification of other IUE high-dispersion spectra, especially for stars that have not been observed in the optical.

Anomalous dynamics of intruders in a crowded environment of mobile obstacles

PubMed Central

Sentjabrskaja, Tatjana; Zaccarelli, Emanuela; De Michele, Cristiano; Sciortino, Francesco; Tartaglia, Piero; Voigtmann, Thomas; Egelhaaf, Stefan U.; Laurati, Marco

2016-01-01

Many natural and industrial processes rely on constrained transport, such as proteins moving through cells, particles confined in nanocomposite materials or gels, individuals in highly dense collectives and vehicular traffic conditions. These are examples of motion through crowded environments, in which the host matrix may retain some glass-like dynamics. Here we investigate constrained transport in a colloidal model system, in which dilute small spheres move in a slowly rearranging, glassy matrix of large spheres. Using confocal differential dynamic microscopy and simulations, here we discover a critical size asymmetry, at which anomalous collective transport of the small particles appears, manifested as a logarithmic decay of the density autocorrelation functions. We demonstrate that the matrix mobility is central for the observed anomalous behaviour. These results, crucially depending on size-induced dynamic asymmetry, are of relevance for a wide range of phenomena ranging from glassy systems to cell biology. PMID:27041068

Effects of urban sprawl on obesity.

PubMed

Zhao, Zhenxiang; Kaestner, Robert

2010-12-01

In this paper, we examine the effect of changes in population density-urban sprawl-between 1970 and 2000 on BMI and obesity of residents in metropolitan areas in the U.S. We address the possible endogeneity of population density by using a two-step instrumental variables approach. We exploit the plausibly exogenous variation in population density caused by the expansion of the U.S. Interstate Highway System, which largely followed the original 1947 plan for the Interstate Highway System. We find a negative association between population density and obesity, and estimates are robust across a wide range of specifications. Estimates indicate that if the average metropolitan area had not experienced the decline in the proportion of population living in dense areas over the last 30 years, the rate of obesity would have been reduced by approximately 13%. Copyright © 2010 Elsevier B.V. All rights reserved.

What's New for Laser Orbital Debris Removal

NASA Astrophysics Data System (ADS)

Phipps, Claude; Lander, Mike

2011-11-01

Orbital debris in low Earth orbit (LEO) are now sufficiently dense that the use of space is threatened by runaway collision cascading. A problem predicted more than thirty years ago, the threat from debris larger than about 1cm is now a reality that we ignore at our peril. The least costly, and most comprehensive, solution is Laser Orbital Debris Removal (LODR). In this approach, a high power pulsed laser on the Earth creates a laser-ablation jet on the debris object's surface which provides the small impulse required to cause it to re-enter and burn up in the atmosphere. The LODR system should be located near the Equator, and includes the laser, a large, agile mirror, and systems for active detection, tracking and atmospheric path correction. In this paper, we discuss advances that have occurred since LODR was first proposed, which make this solution to the debris problem look quite realistic.

Tidal capture of stars by a massive black hole

NASA Technical Reports Server (NTRS)

Novikov, I. D.; Pethick, C. J.; Polnarev, A. G.

1992-01-01

The processes leading to tidal capture of stars by a massive black hole and the consequences of these processes in a dense stellar cluster are discussed in detail. When the amplitude of a tide and the subsequent oscillations are sufficiently large, the energy deposited in a star after periastron passage and formation of a bound orbit cannot be estimated directly using the linear theory of oscillations of a spherical star, but rather numerical estimates must be used. The evolution of a star after tidal capture is discussed. The maximum ratio R of the cross-section for tidal capture to that for tidal disruption is about 3 for real systems. For the case of a stellar system with an empty capture loss cone, even in the case when the impact parameter for tidal capture only slightly exceeds the impact parameter for direct tidal disruption, tidal capture would be much more important than tidal disruption.

Flux and turbulence measurements at a densely built-up site in Marseille: Heat, mass (water and carbon dioxide), and momentum

NASA Astrophysics Data System (ADS)

Grimmond, C. S. B.; Salmond, J. A.; Oke, T. R.; Offerle, B.; Lemonsu, A.

2004-12-01

Eddy covariance (EC) observations above the densely built-up center of Marseille during the Expérience sur site pour contraindre les modèles de pollution atmosphérique et de transport d'émissions (ESCOMPTE) summertime measurement campaign extend current understanding of surface atmosphere exchanges in cities. The instrument array presented opportunities to address issues of the representativeness of local-scale fluxes in urban settings. Separate EC systems operated at two levels, and a telescoping tower allowed the pair to be exposed at two different sets of heights. The flux and turbulence observations taken at the four heights, stratified by wind conditions (mistral wind and sea breeze), are used to address the partitioning of the surface energy balance in an area with large roughness elements. The turbulent sensible heat flux dominates in the daytime, although the storage heat flux is a significant term that peaks before solar noon. The turbulent latent heat flux is small but not negligible. Carbon dioxide fluxes show that this central city district is almost always a source, but the vegetation reduces the magnitude of the fluxes in the afternoon. The atmosphere in such a heavily developed area is rarely stable. The turbulence characteristics support the empirical functions proposed by M. Roth.

Fabrication of highly dense isotropic Nd-Fe-B nylon bonded magnets via extrusion-based additive manufacturing [Fabrication of highly dense isotropic Nd-Fe-B bonded magnets via extrusion-based additive manufacturing

DOE PAGES

Li, Ling; Jones, Kodey E.; Sales, Brian C.; ...

2018-04-03

Magnetically isotropic bonded magnets with a high loading fraction of 70 vol.% Nd-Fe-B are fabricated via an extrusion-based additive manufacturing, or 3D printing system that enables rapid production of large parts. The density of the printed magnet is ~5.2 g/cm 3. The room temperature magnetic properties are: intrinsic coercivity Hci = 8.9 kOe (708.2 kA/m), remanence Br = 5.8 kG (0.58 T), and energy product (BH)max = 7.3 MGOe (58.1 kJ/m 3). The as-printed magnets are then coated with two types of polymers, both of which improve the thermal stability as revealed by flux aging loss measurements. Tensile tests performedmore » at 25 °C and 100 °C show that the ultimate tensile stress (UTS) increases with increasing loading fraction of the magnet powder, and decreases with increasing temperature. AC magnetic susceptibility and resistivity measurements show that the 3D printed Nd-Fe-B bonded magnets exhibit extremely low eddy current loss and high resistivity. Lastly, we demonstrate the performance of the 3D printed magnets in a DC motor configuration via back electromotive force measurements.« less

Convective Instability and Mass Transport of the Diffusion Layer in CO2 Sequestration

NASA Astrophysics Data System (ADS)

Backhaus, S.

2011-12-01

The long-term fate of supercritical (sc) CO2 in saline aquifers is critical to the security of carbon sequestration, an important option for eliminating or reducing the emissions of this most prevalent greenhouse gas. scCO2 is less dense than brine and floats to the top of the aquifer where it is trapped in a metastable state by a geologic feature such as a low permeability cap rock. Dissolution into the underlying brine creates a CO2-brine mixture that is denser than brine, eliminating buoyancy and removing the threat of CO2 escaping back to the atmosphere. If molecular diffusion were the only dissolution mechanism, the CO2 waste stream from a typical large coal-fired electrical power plant may take upward of 10,000 years to no longer pose a threat, however, a convective instability of the dense diffusion boundary layer between the scCO2 and the brine can dramatically increase the dissolution rates, shortening the lifetime of the scCO2 waste pool. We present results of 2D and 3D similitude-correct, laboratory-scale experiments using an analog fluid system. The experiments and flow visualization reveal the onset of the convective instability, the dynamics of the fluid flows during the convective processes, and the long-term mass transfer rates.

Fabrication of highly dense isotropic Nd-Fe-B nylon bonded magnets via extrusion-based additive manufacturing [Fabrication of highly dense isotropic Nd-Fe-B bonded magnets via extrusion-based additive manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Ling; Jones, Kodey E.; Sales, Brian C.

Magnetically isotropic bonded magnets with a high loading fraction of 70 vol.% Nd-Fe-B are fabricated via an extrusion-based additive manufacturing, or 3D printing system that enables rapid production of large parts. The density of the printed magnet is ~5.2 g/cm 3. The room temperature magnetic properties are: intrinsic coercivity Hci = 8.9 kOe (708.2 kA/m), remanence Br = 5.8 kG (0.58 T), and energy product (BH)max = 7.3 MGOe (58.1 kJ/m 3). The as-printed magnets are then coated with two types of polymers, both of which improve the thermal stability as revealed by flux aging loss measurements. Tensile tests performedmore » at 25 °C and 100 °C show that the ultimate tensile stress (UTS) increases with increasing loading fraction of the magnet powder, and decreases with increasing temperature. AC magnetic susceptibility and resistivity measurements show that the 3D printed Nd-Fe-B bonded magnets exhibit extremely low eddy current loss and high resistivity. Lastly, we demonstrate the performance of the 3D printed magnets in a DC motor configuration via back electromotive force measurements.« less

Application of dense gas techniques for the production of fine particles.

PubMed

Foster, Neil R; Dehghani, Fariba; Charoenchaitrakoo, Kiang M; Warwick, Barry

2003-01-01

The feasibility of using dense gas techniques such as rapid expansion of supercritical solutions (RESS) and aerosol solvent extraction system (ASES) for micronization of pharmaceutical compounds is demonstrated. The chiral nonsteroidal anti-inflammatory racemic ibuprofen is soluble in carbon dioxide at 35 degrees C and pressures above 90 bar. The particle size decreased to less than 2 microm while the degree of crystallinity was slightly decreased when processed by RESS. The dissolution rate of the ibuprofen (a poorly water-soluble compound) was significantly enhanced after processing by RESS. The nonsteroidal anti-inflammatory drug Cu2(indomethacin)4L2(Cu-Indo); (L = dimethylformamide [DMF]), which possessed very low solubility in supercritical CO2, was successfully micronized by ASES at 25 degrees C and 68.9 bar using DMF as the solvent and CO2 as the antisolvent. The concentration of solute dramatically influenced the precipitate characteristics. The particles obtained from the ASES process were changed from bipyramidal to spherical, with particle size less than 5 microm, as the concentration increased from 5 to 100 mg/g. A further increase in solute concentration to 200 mg/g resulted in large porous spheres, between 20 and 50 micron, when processing Cu-Indo by the ASES method. The dissolution rate of the micronized Cu-Indo was significantly higher than the commercial product.

Regulation of Dense-Core Granule Replenishment by Autocrine BMP Signalling in Drosophila Secondary Cells.

PubMed

Redhai, Siamak; Hellberg, Josephine E E U; Wainwright, Mark; Perera, Sumeth W; Castellanos, Felix; Kroeger, Benjamin; Gandy, Carina; Leiblich, Aaron; Corrigan, Laura; Hilton, Thomas; Patel, Benjamin; Fan, Shih-Jung; Hamdy, Freddie; Goberdhan, Deborah C I; Wilson, Clive

2016-10-01

Regulated secretion by glands and neurons involves release of signalling molecules and enzymes selectively concentrated in dense-core granules (DCGs). Although we understand how many secretagogues stimulate DCG release, how DCG biogenesis is then accelerated to replenish the DCG pool remains poorly characterised. Here we demonstrate that each prostate-like secondary cell (SC) in the paired adult Drosophila melanogaster male accessory glands contains approximately ten large DCGs, which are loaded with the Bone Morphogenetic Protein (BMP) ligand Decapentaplegic (Dpp). These DCGs can be marked in living tissue by a glycophosphatidylinositol (GPI) lipid-anchored form of GFP. In virgin males, BMP signalling is sporadically activated by constitutive DCG secretion. Upon mating, approximately four DCGs are typically released immediately, increasing BMP signalling, primarily via an autocrine mechanism. Using inducible knockdown specifically in adult SCs, we show that secretion requires the Soluble NSF Attachment Protein, SNAP24. Furthermore, mating-dependent BMP signalling not only promotes cell growth, but is also necessary to accelerate biogenesis of new DCGs, restoring DCG number within 24 h. Our analysis therefore reveals an autocrine BMP-mediated feedback mechanism for matching DCG release to replenishment as secretion rates fluctuate, and might explain why in other disease-relevant systems, like pancreatic β-cells, BMP signalling is also implicated in the control of secretion.

Regulation of Dense-Core Granule Replenishment by Autocrine BMP Signalling in Drosophila Secondary Cells

PubMed Central

Redhai, Siamak; Hellberg, Josephine E. E. U.; Wainwright, Mark; Perera, Sumeth W.; Castellanos, Felix; Kroeger, Benjamin; Gandy, Carina; Leiblich, Aaron; Corrigan, Laura; Hilton, Thomas; Patel, Benjamin; Fan, Shih-Jung; Hamdy, Freddie; Goberdhan, Deborah C. I.

2016-01-01

Regulated secretion by glands and neurons involves release of signalling molecules and enzymes selectively concentrated in dense-core granules (DCGs). Although we understand how many secretagogues stimulate DCG release, how DCG biogenesis is then accelerated to replenish the DCG pool remains poorly characterised. Here we demonstrate that each prostate-like secondary cell (SC) in the paired adult Drosophila melanogaster male accessory glands contains approximately ten large DCGs, which are loaded with the Bone Morphogenetic Protein (BMP) ligand Decapentaplegic (Dpp). These DCGs can be marked in living tissue by a glycophosphatidylinositol (GPI) lipid-anchored form of GFP. In virgin males, BMP signalling is sporadically activated by constitutive DCG secretion. Upon mating, approximately four DCGs are typically released immediately, increasing BMP signalling, primarily via an autocrine mechanism. Using inducible knockdown specifically in adult SCs, we show that secretion requires the Soluble NSF Attachment Protein, SNAP24. Furthermore, mating-dependent BMP signalling not only promotes cell growth, but is also necessary to accelerate biogenesis of new DCGs, restoring DCG number within 24 h. Our analysis therefore reveals an autocrine BMP-mediated feedback mechanism for matching DCG release to replenishment as secretion rates fluctuate, and might explain why in other disease-relevant systems, like pancreatic β-cells, BMP signalling is also implicated in the control of secretion. PMID:27727275

Fast Molecular Cloud Destruction Requires Fast Cloud Formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mac Low, Mordecai-Mark; Burkert, Andreas; Ibáñez-Mejía, Juan C., E-mail: mordecai@amnh.org, E-mail: burkert@usm.lmu.de, E-mail: ibanez@ph1.uni-koeln.de

A large fraction of the gas in the Galaxy is cold, dense, and molecular. If all this gas collapsed under the influence of gravity and formed stars in a local free-fall time, the star formation rate in the Galaxy would exceed that observed by more than an order of magnitude. Other star-forming galaxies behave similarly. Yet, observations and simulations both suggest that the molecular gas is indeed gravitationally collapsing, albeit hierarchically. Prompt stellar feedback offers a potential solution to the low observed star formation rate if it quickly disrupts star-forming clouds during gravitational collapse. However, this requires that molecular cloudsmore » must be short-lived objects, raising the question of how so much gas can be observed in the molecular phase. This can occur only if molecular clouds form as quickly as they are destroyed, maintaining a global equilibrium fraction of dense gas. We therefore examine cloud formation timescales. We first demonstrate that supernova and superbubble sweeping cannot produce dense gas at the rate required to match the cloud destruction rate. On the other hand, Toomre gravitational instability can reach the required production rate. We thus argue that, although dense, star-forming gas may last only around a single global free-fall time; the dense gas in star-forming galaxies can globally exist in a state of dynamic equilibrium between formation by gravitational instability and disruption by stellar feedback. At redshift z ≳ 2, the Toomre instability timescale decreases, resulting in a prediction of higher molecular gas fractions at early times, in agreement with the observations.« less

Shear-induced laning transition in a confined colloidal film

NASA Astrophysics Data System (ADS)

Gerloff, Sascha; Vezirov, Tarlan A.; Klapp, Sabine H. L.

2017-06-01

Using Brownian dynamics simulations, we investigate a dense system of charged colloids exposed to shear flow in a confined (slit-pore) geometry. The equilibrium system at zero flow consists of three well-pronounced layers with a squarelike crystalline in-plane structure. We demonstrate that, for sufficiently large shear rates, the middle layer separates into two sublayers where the particles organize into moving lanes with opposite velocities. The formation of this "microlaned" state results in a destruction of the applied shear profile; it also has a strong impact on the structure of the system, and on its rheology as measured by the elements of the stress tensor. At higher shear rates, we observe a disordered state and finally a recrystallization reminiscent of the behavior of bilayer films. We also discuss the system size dependence and the robustness of the microlaned state against variations of the slit-pore width. In fact, for a pore width allowing for four layers, we observe a similar shear-induced state in which the system splits into two domains with opposite velocities.

A wireless data acquisition system for acoustic emission testing

NASA Astrophysics Data System (ADS)

Zimmerman, A. T.; Lynch, J. P.

2013-01-01

As structural health monitoring (SHM) systems have seen increased demand due to lower costs and greater capabilities, wireless technologies have emerged that enable the dense distribution of transducers and the distributed processing of sensor data. In parallel, ultrasonic techniques such as acoustic emission (AE) testing have become increasingly popular in the non-destructive evaluation of materials and structures. These techniques, which involve the analysis of frequency content between 1 kHz and 1 MHz, have proven effective in detecting the onset of cracking and other early-stage failure in active structures such as airplanes in flight. However, these techniques typically involve the use of expensive and bulky monitoring equipment capable of accurately sensing AE signals at sampling rates greater than 1 million samples per second. In this paper, a wireless data acquisition system is presented that is capable of collecting, storing, and processing AE data at rates of up to 20 MHz. Processed results can then be wirelessly transmitted in real-time, creating a system that enables the use of ultrasonic techniques in large-scale SHM systems.

A system for household enumeration and re-identification in densely populated slums to facilitate community research, education, and advocacy.

PubMed

Thomson, Dana R; Shitole, Shrutika; Shitole, Tejal; Sawant, Kiran; Subbaraman, Ramnath; Bloom, David E; Patil-Deshmukh, Anita

2014-01-01

We devised and implemented an innovative Location-Based Household Coding System (LBHCS) appropriate to a densely populated informal settlement in Mumbai, India. LBHCS codes were designed to double as unique household identifiers and as walking directions; when an entire community is enumerated, LBHCS codes can be used to identify the number of households located per road (or lane) segment. LBHCS was used in community-wide biometric, mental health, diarrheal disease, and water poverty studies. It also facilitated targeted health interventions by a research team of youth from Mumbai, including intensive door-to-door education of residents, targeted follow-up meetings, and a full census. In addition, LBHCS permitted rapid and low-cost preparation of GIS mapping of all households in the slum, and spatial summation and spatial analysis of survey data. LBHCS was an effective, easy-to-use, affordable approach to household enumeration and re-identification in a densely populated informal settlement where alternative satellite imagery and GPS technologies could not be used.

Shell-corona microgels from double interpenetrating networks.

PubMed

Rudyak, Vladimir Yu; Gavrilov, Alexey A; Kozhunova, Elena Yu; Chertovich, Alexander V

2018-04-18

Polymer microgels with a dense outer shell offer outstanding features as universal carriers for different guest molecules. In this paper, microgels formed by an interpenetrating network comprised of collapsed and swollen subnetworks are investigated using dissipative particle dynamics (DPD) computer simulations, and it is found that such systems can form classical core-corona structures, shell-corona structures, and core-shell-corona structures, depending on the subchain length and molecular mass of the system. The core-corona structures consisting of a dense core and soft corona are formed at small microgel sizes when the subnetworks are able to effectively separate in space. The most interesting shell-corona structures consist of a soft cavity in a dense shell surrounded with a loose corona, and are found at intermediate gel sizes; the area of their existence depends on the subchain length and the corresponding mesh size. At larger molecular masses the collapsing network forms additional cores inside the soft cavity, leading to the core-shell-corona structure.

Integration of both dense wavelength-division multiplexing and coarse wavelength-division multiplexing demultiplexer on one photonic crystal chip

NASA Astrophysics Data System (ADS)

Tian, Huiping; Shen, Guansheng; Liu, Weijia; Ji, Yuefeng

2013-07-01

An integrated model of photonic crystal (PC) demultiplexer that can be used to combine dense wavelength-division multiplexing (DWDM) and coarse wavelength-division multiplexing (CWDM) systems is first proposed. By applying the PC demultiplexer, dense channel spacing 0.8 nm and coarse channel spacing 20 nm are obtained at the same time. The transmission can be improved to nearly 90%, and the crosstalk can be decreased to less than -18 dB by enlarging the width of the bus waveguide. The total size of the device is 21×42 μm2. Four channels on one side of the demultiplexer can achieve DWDM in the wavelength range between 1575 and 1578 nm, and the other four channels on the other side can achieve CWDM in the wavelength range between 1490 and 1565 nm, respectively. The demonstrated demultiplexer can be applied in the future CWDM and DWDM system, and the architecture costs can be significantly reduced.

Fine-structural changes in the midgut of old Drosophila melanogaster

NASA Technical Reports Server (NTRS)

Anton-Erxleben, F.; Miquel, J.; Philpott, D. E.

1983-01-01

Senescent fine-structural changes in the midgut of Drosophila melanogaster are investigated. A large number of midgut mitochondria in old flies exhibit nodular cristae and a tubular system located perpendicular to the normal cristae orientation. Anterior intestinal cells show a senescent accumulation of age pigment, either with a surrounding two-unit membrane or without any membrane. The predominant localization of enlarged mitochondria and pigment in the luminal gut region may be related to the polarized metabolism of the intestinal cells. Findings concur with previous observations of dense-body accumulations and support the theory that mitochondria are involved in the aging of fixed post-mitotic cells. Demonstrated by statistical analyses is that mitochondrial size increase is related to mitochondrial variation increase.

Percolation transition in Yang-Mills matter at a finite number of colors.

PubMed

Lottini, Stefano; Torrieri, Giorgio

2011-10-07

We examine baryonic matter at a quark chemical potential of the order of the confinement scale μ(q)∼Λ(QCD). In this regime, quarks are supposed to be confined but baryons are close to the "tightly packed limit" where they nearly overlap in configuration space. We show that this system will exhibit a percolation phase transition when varied in the number of colors N(c): at high N(c), large distance correlations at the quark level are possible even if the quarks are essentially confined. At low N(c), this does not happen. We discuss the relevance of this for dense nuclear matter, and argue that our results suggest a new "phase transition," varying N(c) at constant μ(q).

Pulsed x-ray imaging of high-density objects using a ten picosecond high-intensity laser driver

NASA Astrophysics Data System (ADS)

Rusby, D. R.; Brenner, C. M.; Armstrong, C.; Wilson, L. A.; Clarke, R.; Alejo, A.; Ahmed, H.; Butler, N. M. H.; Haddock, D.; Higginson, A.; McClymont, A.; Mirfayzi, S. R.; Murphy, C.; Notley, M.; Oliver, P.; Allott, R.; Hernandez-Gomez, C.; Kar, S.; McKenna, P.; Neely, D.

2016-10-01

Point-like sources of X-rays that are pulsed (sub nanosecond), high energy (up to several MeV) and bright are very promising for industrial and security applications where imaging through large and dense objects is required. Highly penetrating X-rays can be produced by electrons that have been accelerated by a high intensity laser pulse incident onto a thin solid target. We have used a pulse length of 10ps to accelerate electrons to create a bright x-ray source. The bremsstrahlung temperature was measured for a laser intensity from 8.5-12×1018 W/cm2. These x-rays have sequentially been used to image high density materials using image plate and a pixelated scintillator system.

Ganges River Delta

NASA Technical Reports Server (NTRS)

2002-01-01

The Ganges River forms an extensive delta where it empties into the Bay of Bengal. The delta is largely covered with a swamp forest known as the Sunderbans, which is home to the Royal Bengal Tiger. It is also home to most of Bangladesh, one of the world's most densely populated countries. Roughly 120 million people live on the Ganges Delta under threat of repeated catastrophic floods due to heavy runoff of meltwater from the Himalayas, and due to the intense rainfall during the monsoon season. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on February 28, 2000. This is a false-color composite image made using green, infrared, and blue wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

Early detection of protozoan grazers in algal biofuel cultures.

PubMed

Day, John G; Thomas, Naomi J; Achilles-Day, Undine E M; Leakey, Raymond J G

2012-06-01

Future micro-algal biofuels will most likely be derived from open-pond production systems. These are by definition open to "invasion" by grazers, which could devastate micro-algal mass-cultures. There is an urgent requirement for methodologies capable of early detection and control of grazers in dense algal cultures. In this study a model system employing the marine alga Nannochloropsis oculata was challenged by grazers including ciliates, amoebae and a heterotrophic dinoflagellate. A FlowCAM flow-cytometer was used to detect all grazers investigated (size range <20->80 μm in length) in the presence of algae. Detection limits were <10 cells ml(-1) for both "large" and "small" model grazers, Euplotes vannus (80 × 45 μm) and an unidentified holotrichous ciliate (~18 × 8 μm) respectively. Furthermore, the system can distinguish the presence of ciliates in N. oculata cultures with biotechnologically relevant cell densities; i.e. >1.4 × 10(8) cells ml(-1) (>0.5 g l(-1) dry wt.). Copyright © 2012 Elsevier Ltd. All rights reserved.

High Accuracy Monocular SFM and Scale Correction for Autonomous Driving.

PubMed

Song, Shiyu; Chandraker, Manmohan; Guest, Clark C

2016-04-01

We present a real-time monocular visual odometry system that achieves high accuracy in real-world autonomous driving applications. First, we demonstrate robust monocular SFM that exploits multithreading to handle driving scenes with large motions and rapidly changing imagery. To correct for scale drift, we use known height of the camera from the ground plane. Our second contribution is a novel data-driven mechanism for cue combination that allows highly accurate ground plane estimation by adapting observation covariances of multiple cues, such as sparse feature matching and dense inter-frame stereo, based on their relative confidences inferred from visual data on a per-frame basis. Finally, we demonstrate extensive benchmark performance and comparisons on the challenging KITTI dataset, achieving accuracy comparable to stereo and exceeding prior monocular systems. Our SFM system is optimized to output pose within 50 ms in the worst case, while average case operation is over 30 fps. Our framework also significantly boosts the accuracy of applications like object localization that rely on the ground plane.

The nature of the dense obscuring material in the nucleus of NGC 1068

NASA Technical Reports Server (NTRS)

Tacconi, L. J.; Genzel, R.; Blietz, M.; Cameron, M.; Harris, A. I.; Madden, S.

1994-01-01

High spatial and spectral resolution observations of the distribution, physical parameters, and kinematics of the molecular interstellar medium toward the nucleus of the Seyfert 2 galaxy NGC 1068 are reported. The data consist of 2.4 by 3.4 arcseconds resolution interferometry of the 88.6 GHz HCN J = 1 towards 0 line at 17 km/s spectral resolution, single dish observations of several mm/submm isotopic lines of CO and HCN, and 0.85 arcseconds imaging spectroscopy of the 2.12 micron H2 S(1) line at a velocity resolution of 110 km/s. The central few hundred parsecs of NGC 1068 contain a system of dense (N(H2) approximately 10(exp 5) cm(exp -3)), warm (T greater than or equal to 70 K) molecular cloud cores. The low density molecular envelopes have probably been stripped by the nuclear wind and radiation. The molecular gas layer is located in the plane of NGC 1068's large scale disk (inclination approximately 35 deg) and orbits in elliptical streamlines in response to the central stellar bar. The spatial distribution of the 2 micron H2 emission suggests that gas is shocked at the leading edge of the bar, probably resulting in gas influx into the central 100 pc at a rate of a few solar mass per year. In addition to large scale streaming (with a solid body rotation curve), the HCN velocity field requires the presence of random motions of order 100 km/s. We interpret these large random motions as implying the nuclear gas disk to be very thick (scale height/radius approximately 1), probably as the result of the impact of nuclear radiation and wind on orbiting molecular clouds. Geometry and column density of the molecular cloud layer between approximately 30 pc to 300 pc from the nucleus can plausibly account for the nuclear obscuration and anisotropy of the radiation field in the visible and UV.

Natural Deposition Strategy for Interfacial, Self-Assembled, Large-Scale, Densely Packed, Monolayer Film with Ligand-Exchanged Gold Nanorods for In Situ Surface-Enhanced Raman Scattering Drug Detection.

PubMed

Mao, Mei; Zhou, Binbin; Tang, Xianghu; Chen, Cheng; Ge, Meihong; Li, Pan; Huang, Xingjiu; Yang, Liangbao; Liu, Jinhuai

2018-03-15

Liquid interfacial self-assembly of metal nanoparticles holds great promise for its various applications, such as in tunable optical devices, plasmonics, sensors, and catalysis. However, the construction of large-area, ordered, anisotropic, nanoparticle monolayers and the acquisition of self-assembled interface films are still significant challenges. Herein, a rapid, validated method to fabricate large-scale, close-packed nanomaterials at the cyclohexane/water interface, in which hydrophilic cetyltrimethylammonium bromide coated nanoparticles and gold nanorods (AuNRs) self-assemble into densely packed 2D arrays by regulating the surface ligand and suitable inducer, is reported. Decorating AuNRs with polyvinylpyrrolidone not only extensively decreases the charge of AuNRs, but also diminishes repulsive forces. More importantly, a general, facile, novel technique to transfer an interfacial monolayer through a designed in situ reaction cell linked to a microfluidic chip is revealed. The self-assembled nanofilm can then automatically settle on the substrate and be directly detected in the reaction cell in situ by means of a portable Raman spectrometer. Moreover, a close-packed monolayer of self-assembled AuNRs provides massive, efficient hotspots to create great surface-enhanced Raman scattering (SERS) enhancement, which provides high sensitivity and reproducibility as the SERS-active substrate. Furthermore, this strategy was exploited to detect drug molecules in human urine for cyclohexane-extracted targets acting as the oil phase to form an oil/water interface. A portable Raman spectrometer was employed to detect methamphetamine down to 100 ppb levels in human urine, exhibiting excellent practicability. As a universal platform, handy tool, and fast pretreatment method with a good capability for drug detection in biological systems, this technique shows great promise for rapid, credible, and on-spot drug detection. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highway fog warning system

DOT National Transportation Integrated Search

1999-04-01

The need for a highway fog warning system has long been internationally recognized. With such a system, motorists can avoid tragic pile-up accidents caused by dense or patchy fog. The development of a cost-effective highway visibility sensor that mea...

Invasive Species Biology, Control, and Research. Part 2. Multiflora Rose (Rosa multiflora)

DTIC Science & Technology

2008-11-01

species and alter long-term successional processes (Vidra et al. 2007), although they could also enhance the biodiversity of the plant community...3. Biological control ( fungi or insects) 4. Fire management 5. Prescribed grazing. Because the plant grows in large, dense thickets, possesses

THE DNAPL REMEDIATION CHALLENGE: IS THERE A CASE FOR SOURCE DEPLETION?

EPA Science Inventory

Releases of Dense Non-Aqueous Phase Liquids (DNAPLs) at a large number of public and private sector sites in the United States pose significant challenges in site remediation and long-term site management. Extensive contamination of groundwater occurs as a result of significant ...

Control of rhododendron by basal spray

Treesearch

Harry W. Yawney

1962-01-01

Rhododendron (Rhododendron maximum L.) is a large shrub that presents problems in timber management throughout the Appalachian Mountains. Although sometimes found in single clumps, rhododendron characteristically occurs in extensive dense thickets reaching heights of 10 feet or more (fig. 1). Of major concern to foresters is the difficulty in...

Analysis of Driven Pile Capacity within Pre-Bored Soil : Research Project Capsule

DOT National Transportation Integrated Search

2017-10-01

Pre-boring is a method used to facilitate large displacement pile driving in hard/dense soils (see Figure 1). By pre-boring a pilot hole, the end bearing and side friction within the pre-bored zone are reduced, thus aiding pile driving installation. ...

MONITOIRNG OF A CONTROLLED DNAPL SPILL USING A PROTOTYPE DIELECTRIC LOGGING TOOL

EPA Science Inventory

The U. S. Geological Survey (USGS) utilized their prototype dielectric logging tool to monitor a controlled Dense Non-Aqueous Phase Liquid (DNAPL) spill into a large tank located at the University of California Richmond Field Station (RFS) containing multiple sand and clayey sand...

Numerical Modeling of Deep Mantle Flow: Thermochemical Convection and Entrainment

NASA Astrophysics Data System (ADS)

Mulyukova, Elvira; Steinberger, Bernhard; Dabrowski, Marcin; Sobolev, Stephan

2013-04-01

One of the most robust results from tomographic studies is the existence of two antipodally located Large Low Shear Velocity Provinces (LLSVPs) at the base of the mantle, which appear to be chemically denser than the ambient mantle. Results from reconstruction studies (Torsvik et al., 2006) infer that the LLSVPs are stable, long-lived, and are sampled by deep mantle plumes that rise predominantly from their margins. The origin of the dense material is debated, but generally falls within three categories: (i) a primitive layer that formed during magma ocean crystallization, (ii) accumulation of a dense eclogitic component from the recycled oceanic crust, and (iii) outer core material leaking into the lower mantle. A dense layer underlying a less dense ambient mantle is gravitationally stable. However, the flow due to thermal density variations, i.e. hot rising plumes and cold downwelling slabs, may deform the layer into piles with higher topography. Further deformation may lead to entrainment of the dense layer, its mixing with the ambient material, and even complete homogenisation with the rest of the mantle. The amount of the anomalous LLSVP-material that gets entrained into the rising plumes poses a constraint on the survival time of the LLSVPs, as well as on the plume buoyancy, on the lithospheric uplift associated with plume interaction and geochemical signature of the erupted lavas observed at the Earth's surface. Recent estimates for the plume responsible for the formation of the Siberian Flood Basalts give about 15% of entrained dense recycled oceanic crust, which made the hot mantle plume almost neutrally buoyant (Sobolev et al., 2011). In this numerical study we investigate the mechanics of entrainment of a dense basal layer by convective mantle flow. We observe that the types of flow that promote entrainment of the dense layer are (i) upwelling of the dense layer when it gets heated enough to overcome its stabilizing chemical density anomaly, (ii) upwelling of the ambient material in the vicinity of the dense material (mechanism of selective withdrawal (Lister, 1989)), and (iii) cold downwellings sliding along the bottom boundary, and forcing the dense material upwards. The objective of this study is to compare the efficiency of entrainment by each of these mechanisms, and its dependence on the density and viscosity anomaly of the dense material with respect to the ambient mantle. To perform this study, we have developed a two-dimensional FEM code to model thermal convection in a hollow cylinder domain with presence of chemical heterogeneities, and using a realistic viscosity profile. We present the results of the simulations that demonstrate the entrainment mechanisms described above. In addition, we perfom numerical experiments in a Cartesian box domain, where the bottom right boundary of the box is deformed to resemble the geometry of an LLSVP edge. In some of the experiments, the bottom left part of the boundary is moving towards the right boundary, simulating a slab sliding along the core-mantle boundary towards an LLSVP. These experiments allow a detailed study of the process of entrainment, and its role in the thermochemical evolution of the Earth.

Dissipationless Hall current in dense quark matter in a magnetic field

DOE PAGES

Ferrer, Efrain J.; de la Incera, V.

2017-03-29

Here, we show the realization of axion electrodynamics within the Dual Chiral Density Wave phase of dense quark matter in the presence of a magnetic field. This system exhibits an anomalous dissipationless Hall current perpendicular to the magnetic field and an anomalous electric charge density. This connection to topological insulators and 3D optical lattices, as well as possible implications for heavy-ion collisions and neutron stars are outlined.

Energy Flow in Dense Off-Equilibrium Plasma

DTIC Science & Technology

2016-07-15

akT e in our system100 i e T T Teller 1966 Smoking Gun Experiment: Laser Breakdown in COLD gas In going from room to liquid Nitrogen temperature...oflaser breakdown have revealed a new phase of off-equilibrium plasma that has a tensile strength similar to a liquid , and reduced ion-electron...approved for public release. Part 1: Energy Balance in Sonoluminescing Dense Plasma Sonoluminescence occurs from rapid implosion of gas bubbles caused to

A Census of Large-scale (≥10 PC), Velocity-coherent, Dense Filaments in the Northern Galactic Plane: Automated Identification Using Minimum Spanning Tree

NASA Astrophysics Data System (ADS)

Wang, Ke; Testi, Leonardo; Burkert, Andreas; Walmsley, C. Malcolm; Beuther, Henrik; Henning, Thomas

2016-09-01

Large-scale gaseous filaments with lengths up to the order of 100 pc are on the upper end of the filamentary hierarchy of the Galactic interstellar medium (ISM). Their association with respect to the Galactic structure and their role in Galactic star formation are of great interest from both an observational and theoretical point of view. Previous “by-eye” searches, combined together, have started to uncover the Galactic distribution of large filaments, yet inherent bias and small sample size limit conclusive statistical results from being drawn. Here, we present (1) a new, automated method for identifying large-scale velocity-coherent dense filaments, and (2) the first statistics and the Galactic distribution of these filaments. We use a customized minimum spanning tree algorithm to identify filaments by connecting voxels in the position-position-velocity space, using the Bolocam Galactic Plane Survey spectroscopic catalog. In the range of 7\\buildrel{\\circ}\\over{.} 5≤slant l≤slant 194^\\circ , we have identified 54 large-scale filaments and derived mass (˜ {10}3{--}{10}5 {M}⊙ ), length (10-276 pc), linear mass density (54-8625 {M}⊙ pc-1), aspect ratio, linearity, velocity gradient, temperature, fragmentation, Galactic location, and orientation angle. The filaments concentrate along major spiral arms. They are widely distributed across the Galactic disk, with 50% located within ±20 pc from the Galactic mid-plane and 27% run in the center of spiral arms. An order of 1% of the molecular ISM is confined in large filaments. Massive star formation is more favorable in large filaments compared to elsewhere. This is the first comprehensive catalog of large filaments that can be useful for a quantitative comparison with spiral structures and numerical simulations.

First-principles calculations of K-shell X-ray absorption spectra for warm dense nitrogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zi; Zhang, Shen; Kang, Wei

2016-05-15

X-ray absorption spectrum is a powerful tool for atomic structure detection on warm dense matter. Here, we perform first-principles molecular dynamics and X-ray absorption spectrum calculations on warm dense nitrogen along a Hugoniot curve. From the molecular dynamics trajectory, the detailed atomic structures are examined for each thermodynamical condition. The K-shell X-ray absorption spectrum is calculated, and its changes with temperature and pressure along the Hugoniot curve are discussed. The warm dense nitrogen systems may contain isolated nitrogen atoms, N{sub 2} molecules, and nitrogen clusters, which show quite different contributions to the total X-ray spectrum due to their different electronmore » density of states. The changes of X-ray spectrum along the Hugoniot curve are caused by the different nitrogen structures induced by the temperature and the pressure. Some clear signatures on X-ray spectrum for different thermodynamical conditions are pointed out, which may provide useful data for future X-ray experiments.« less