saddle point search: Topics by Science.gov

Sample records for saddle point search

Acceleration of saddle-point searches with machine learning.

PubMed

Peterson, Andrew A

2016-08-21

In atomistic simulations, the location of the saddle point on the potential-energy surface (PES) gives important information on transitions between local minima, for example, via transition-state theory. However, the search for saddle points often involves hundreds or thousands of ab initio force calls, which are typically all done at full accuracy. This results in the vast majority of the computational effort being spent calculating the electronic structure of states not important to the researcher, and very little time performing the calculation of the saddle point state itself. In this work, we describe how machine learning (ML) can reduce the number of intermediate ab initio calculations needed to locate saddle points. Since machine-learning models can learn from, and thus mimic, atomistic simulations, the saddle-point search can be conducted rapidly in the machine-learning representation. The saddle-point prediction can then be verified by an ab initio calculation; if it is incorrect, this strategically has identified regions of the PES where the machine-learning representation has insufficient training data. When these training data are used to improve the machine-learning model, the estimates greatly improve. This approach can be systematized, and in two simple example problems we demonstrate a dramatic reduction in the number of ab initio force calls. We expect that this approach and future refinements will greatly accelerate searches for saddle points, as well as other searches on the potential energy surface, as machine-learning methods see greater adoption by the atomistics community.
Acceleration of saddle-point searches with machine learning

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

Peterson, Andrew A., E-mail: andrew-peterson@brown.edu

In atomistic simulations, the location of the saddle point on the potential-energy surface (PES) gives important information on transitions between local minima, for example, via transition-state theory. However, the search for saddle points often involves hundreds or thousands of ab initio force calls, which are typically all done at full accuracy. This results in the vast majority of the computational effort being spent calculating the electronic structure of states not important to the researcher, and very little time performing the calculation of the saddle point state itself. In this work, we describe how machine learning (ML) can reduce the numbermore » of intermediate ab initio calculations needed to locate saddle points. Since machine-learning models can learn from, and thus mimic, atomistic simulations, the saddle-point search can be conducted rapidly in the machine-learning representation. The saddle-point prediction can then be verified by an ab initio calculation; if it is incorrect, this strategically has identified regions of the PES where the machine-learning representation has insufficient training data. When these training data are used to improve the machine-learning model, the estimates greatly improve. This approach can be systematized, and in two simple example problems we demonstrate a dramatic reduction in the number of ab initio force calls. We expect that this approach and future refinements will greatly accelerate searches for saddle points, as well as other searches on the potential energy surface, as machine-learning methods see greater adoption by the atomistics community.« less
Localized saddle-point search and application to temperature-accelerated dynamics

NASA Astrophysics Data System (ADS)

Shim, Yunsic; Callahan, Nathan B.; Amar, Jacques G.

2013-03-01

We present a method for speeding up temperature-accelerated dynamics (TAD) simulations by carrying out a localized saddle-point (LSAD) search. In this method, instead of using the entire system to determine the energy barriers of activated processes, the calculation is localized by only including a small chunk of atoms around the atoms directly involved in the transition. Using this method, we have obtained N-independent scaling for the computational cost of the saddle-point search as a function of system size N. The error arising from localization is analyzed using a variety of model systems, including a variety of activated processes on Ag(100) and Cu(100) surfaces, as well as multiatom moves in Cu radiation damage and metal heteroepitaxial growth. Our results show significantly improved performance of TAD with the LSAD method, for the case of Ag/Ag(100) annealing and Cu/Cu(100) growth, while maintaining a negligibly small error in energy barriers.
Computation of saddle point of attachment

NASA Technical Reports Server (NTRS)

Hung, Ching-Mao; Sung, Chao-Ho; Chen, Chung-Lung

1991-01-01

Low-speed flows over a cylinder mounted on a flat plate are studied numerically in order to confirm the existence of a saddle point of attachment in the flow before an obstacle, to analyze the flow characteristics near the saddle point theoretically, and to address the significance of the saddle point of attachment to the construction of external flow structures, the interpretation of experimental surface oil-flow patterns, and the theoretical definition of three-dimensional flow separation. Two numerical codes, one for an incompressible flow and another for a compressible flow, are used for various Mach numbers, Reynolds numbers, grid sizes, and numbers of grid points. It is pointed out that the potential presence of a saddle point of attachment means that a line of 'oil accumulation' from both sides of a skin-friction line emanating outward from a saddle point can be either a line of separation or a line of attachment.
Sampling saddle points on a free energy surface

NASA Astrophysics Data System (ADS)

Samanta, Amit; Chen, Ming; Yu, Tang-Qing; Tuckerman, Mark; E, Weinan

2014-04-01

Many problems in biology, chemistry, and materials science require knowledge of saddle points on free energy surfaces. These saddle points act as transition states and are the bottlenecks for transitions of the system between different metastable states. For simple systems in which the free energy depends on a few variables, the free energy surface can be precomputed, and saddle points can then be found using existing techniques. For complex systems, where the free energy depends on many degrees of freedom, this is not feasible. In this paper, we develop an algorithm for finding the saddle points on a high-dimensional free energy surface "on-the-fly" without requiring a priori knowledge the free energy function itself. This is done by using the general strategy of the heterogeneous multi-scale method by applying a macro-scale solver, here the gentlest ascent dynamics algorithm, with the needed force and Hessian values computed on-the-fly using a micro-scale model such as molecular dynamics. The algorithm is capable of dealing with problems involving many coarse-grained variables. The utility of the algorithm is illustrated by studying the saddle points associated with (a) the isomerization transition of the alanine dipeptide using two coarse-grained variables, specifically the Ramachandran dihedral angles, and (b) the beta-hairpin structure of the alanine decamer using 20 coarse-grained variables, specifically the full set of Ramachandran angle pairs associated with each residue. For the alanine decamer, we obtain a detailed network showing the connectivity of the minima obtained and the saddle-point structures that connect them, which provides a way to visualize the gross features of the high-dimensional surface.
Saddle point localization of molecular wavefunctions.

PubMed

Mellau, Georg Ch; Kyuberis, Alexandra A; Polyansky, Oleg L; Zobov, Nikolai; Field, Robert W

2016-09-15

The quantum mechanical description of isomerization is based on bound eigenstates of the molecular potential energy surface. For the near-minimum regions there is a textbook-based relationship between the potential and eigenenergies. Here we show how the saddle point region that connects the two minima is encoded in the eigenstates of the model quartic potential and in the energy levels of the [H, C, N] potential energy surface. We model the spacing of the eigenenergies with the energy dependent classical oscillation frequency decreasing to zero at the saddle point. The eigenstates with the smallest spacing are localized at the saddle point. The analysis of the HCN ↔ HNC isomerization states shows that the eigenstates with small energy spacing relative to the effective (v1, v3, ℓ) bending potentials are highly localized in the bending coordinate at the transition state. These spectroscopically detectable states represent a chemical marker of the transition state in the eigenenergy spectrum. The method developed here provides a basis for modeling characteristic patterns in the eigenenergy spectrum of bound states.
Experimental Study of Saddle Point of Attachment in Laminar Juncture Flow

NASA Technical Reports Server (NTRS)

Coon, Michael D.; Tobak, Murray

1995-01-01

An experimental study of laminar horseshoe vortex flows upstream of a cylinder/flat plate juncture has been conducted to verify the existence of saddle-point-of-attachment topologies. In the classical depiction of this flowfield, a saddle point of separation exists on the flat plate upstream of the cylinder, and the boundary layer separates from the surface. Recent computations have indicated that the topology may actually involve a saddle point of attachment on the surface and additional singular points in the flow. Laser light sheet flow visualizations have been performed on the symmetry plane and crossflow planes to identify the saddle-point-of-attachment flowfields. The visualizations reveal that saddle-point-of-attachment topologies occur over a range of Reynolds numbers in both single and multiple vortex regimes. An analysis of the flow topologies is presented that describes the existence and evolution of the singular points in the flowfield.
Electrons at the monkey saddle: a multicritical Lifshitz point

NASA Astrophysics Data System (ADS)

Shtyk, Alex; Goldstein, Garry; Chamon, Claudio

We consider 2D interacting electrons at a monkey saddle with dispersion px3 - 3pxpy2 . Such a dispersion naturally arises at the multicritical Lifshitz point when three van Hove saddles merge in an elliptical umbilic elementary catastrophe, which we show can be realized in biased bilayer graphene. A multicritical Lifshitz point of this kind can be identified by its signature Landau level behavior Em (Bm) 3 / 2 and related oscillations in thermodynamic and transport properties, such as de Haas-van Alphen and Shubnikov-de Haas oscillations, whose period triples as the system crosses the singularity. We show, in the case of a single monkey saddle, that the non-interacting electron fixed point is unstable to interactions under the renormalization group flow, developing either a superconducting instability or non-Fermi liquid features. Biased bilayer graphene, where there are two non-nested monkey saddles at the K and K' points, exhibits an interplay of competing many-body instabilities, namely s-wave superconductivity, ferromagnetism, and spin- and charge-density wave. DOE DE-FG02-06ER46316.
Electrons at the monkey saddle: A multicritical Lifshitz point

NASA Astrophysics Data System (ADS)

Shtyk, A.; Goldstein, G.; Chamon, C.

2017-01-01

We consider two-dimensional interacting electrons at a monkey saddle with dispersion ∝px3-3 pxpy2 . Such a dispersion naturally arises at the multicritical Lifshitz point when three Van Hove saddles merge in an elliptical umbilic elementary catastrophe, which we show can be realized in biased bilayer graphene. A multicritical Lifshitz point of this kind can be identified by its signature Landau level behavior Em∝(Bm ) 3 /2 and related oscillations in thermodynamic and transport properties, such as de Haas-Van Alphen and Shubnikov-de Haas oscillations, whose period triples as the system crosses the singularity. We show, in the case of a single monkey saddle, that the noninteracting electron fixed point is unstable to interactions under the renormalization-group flow, developing either a superconducting instability or non-Fermi-liquid features. Biased bilayer graphene, where there are two non-nested monkey saddles at the K and K' points, exhibits an interplay of competing many-body instabilities, namely, s -wave superconductivity, ferromagnetism, and spin- and charge-density waves.
The Sun-Earth saddle point: characterization and opportunities to test general relativity

NASA Astrophysics Data System (ADS)

Topputo, Francesco; Dei Tos, Diogene A.; Rasotto, Mirco; Nakamiya, Masaki

2018-04-01

The saddle points are locations where the net gravitational accelerations balance. These regions are gathering more attention within the astrophysics community. Regions about the saddle points present clean, close-to-zero background acceleration environments where possible deviations from General Relativity can be tested and quantified. Their location suggests that flying through a saddle point can be accomplished by leveraging highly nonlinear orbits. In this paper, the geometrical and dynamical properties of the Sun-Earth saddle point are characterized. A systematic approach is devised to find ballistic orbits that experience one or multiple passages through this point. A parametric analysis is performed to consider spacecraft initially on L_{1,2} Lagrange point orbits. Sun-Earth saddle point ballistic fly-through trajectories are evaluated and classified for potential use. Results indicate an abundance of short-duration, regular solutions with a variety of characteristics.
Emphasizing Saddle Points through Game Theory: A Classroom Activity.

ERIC Educational Resources Information Center

Dorrington, Jenny; Jones, Michael A.

2000-01-01

Introduces the necessary game-theoretic background and explains how game-theoretic experiments of the Matching Pennies game can be used as a classroom activity to develop intuition about saddle points. (Author/ASK)
Feature-Based Retinal Image Registration Using D-Saddle Feature

PubMed Central

Hasikin, Khairunnisa; A. Karim, Noor Khairiah; Ahmedy, Fatimah

2017-01-01

Retinal image registration is important to assist diagnosis and monitor retinal diseases, such as diabetic retinopathy and glaucoma. However, registering retinal images for various registration applications requires the detection and distribution of feature points on the low-quality region that consists of vessels of varying contrast and sizes. A recent feature detector known as Saddle detects feature points on vessels that are poorly distributed and densely positioned on strong contrast vessels. Therefore, we propose a multiresolution difference of Gaussian pyramid with Saddle detector (D-Saddle) to detect feature points on the low-quality region that consists of vessels with varying contrast and sizes. D-Saddle is tested on Fundus Image Registration (FIRE) Dataset that consists of 134 retinal image pairs. Experimental results show that D-Saddle successfully registered 43% of retinal image pairs with average registration accuracy of 2.329 pixels while a lower success rate is observed in other four state-of-the-art retinal image registration methods GDB-ICP (28%), Harris-PIIFD (4%), H-M (16%), and Saddle (16%). Furthermore, the registration accuracy of D-Saddle has the weakest correlation (Spearman) with the intensity uniformity metric among all methods. Finally, the paired t-test shows that D-Saddle significantly improved the overall registration accuracy of the original Saddle. PMID:29204257
Analysis of chaotic saddles in a nonlinear vibro-impact system

NASA Astrophysics Data System (ADS)

Feng, Jinqian

2017-07-01

In this paper, a computational investigation of chaotic saddles in a nonlinear vibro-impact system is presented. For a classical Duffing vibro-impact oscillator, we employ the bisection procedure and an improved stagger-and-step method to present evidence of visual chaotic saddles on the fractal basin boundary and in the internal basin, respectively. The results show that the period saddles play an important role in the evolution of chaotic saddle. The dynamics mechanics of three types of bifurcation such as saddle-node bifurcation, chaotic saddle crisis bifurcation and interior chaotic crisis bifurcation are discussed. The results reveal that the period saddle created at saddle-node bifurcation is responsible for the switch of the internal chaotic saddle to the boundary chaotic saddle. At chaotic saddle crisis bifurcation, a large chaotic saddle can divide into two different chaotic saddle connected by a period saddle. The intersection points between stable and unstable manifolds of this period saddle supply access for chaotic orbits from one chaotic saddle to another and eventually induce the coupling of these two chaotic saddle. Interior chaotic crisis bifurcation is associated with the intersection of stable and unstable manifolds of the period saddle connecting two chaotic invariant sets. In addition, the gaps in chaotic saddle is responsible for the fractal structure.
Composite solvers for linear saddle point problems arising from the incompressible Stokes equations with highly heterogeneous viscosity structure

NASA Astrophysics Data System (ADS)

Sanan, P.; Schnepp, S. M.; May, D.; Schenk, O.

2014-12-01

Geophysical applications require efficient forward models for non-linear Stokes flow on high resolution spatio-temporal domains. The bottleneck in applying the forward model is solving the linearized, discretized Stokes problem which takes the form of a large, indefinite (saddle point) linear system. Due to the heterogeniety of the effective viscosity in the elliptic operator, devising effective preconditioners for saddle point problems has proven challenging and highly problem-dependent. Nevertheless, at least three approaches show promise for preconditioning these difficult systems in an algorithmically scalable way using multigrid and/or domain decomposition techniques. The first is to work with a hierarchy of coarser or smaller saddle point problems. The second is to use the Schur complement method to decouple and sequentially solve for the pressure and velocity. The third is to use the Schur decomposition to devise preconditioners for the full operator. These involve sub-solves resembling inexact versions of the sequential solve. The choice of approach and sub-methods depends crucially on the motivating physics, the discretization, and available computational resources. Here we examine the performance trade-offs for preconditioning strategies applied to idealized models of mantle convection and lithospheric dynamics, characterized by large viscosity gradients. Due to the arbitrary topological structure of the viscosity field in geodynamical simulations, we utilize low order, inf-sup stable mixed finite element spatial discretizations which are suitable when sharp viscosity variations occur in element interiors. Particular attention is paid to possibilities within the decoupled and approximate Schur complement factorization-based monolithic approaches to leverage recently-developed flexible, communication-avoiding, and communication-hiding Krylov subspace methods in combination with `heavy' smoothers, which require solutions of large per-node sub-problems, well
Saddles and dynamics in a solvable mean-field model

NASA Astrophysics Data System (ADS)

Angelani, L.; Ruocco, G.; Zamponi, F.

2003-05-01

We use the saddle-approach, recently introduced in the numerical investigation of simple model liquids, in the analysis of a mean-field solvable system. The investigated system is the k-trigonometric model, a k-body interaction mean field system, that generalizes the trigonometric model introduced by Madan and Keyes [J. Chem. Phys. 98, 3342 (1993)] and that has been recently introduced to investigate the relationship between thermodynamics and topology of the configuration space. We find a close relationship between the properties of saddles (stationary points of the potential energy surface) visited by the system and the dynamics. In particular the temperature dependence of saddle order follows that of the diffusivity, both having an Arrhenius behavior at low temperature and a similar shape in the whole temperature range. Our results confirm the general usefulness of the saddle-approach in the interpretation of dynamical processes taking place in interacting systems.
Relative variances of the cadence frequency of cycling under two differential saddle heights

PubMed Central

Chang, Wen-Dien; Fan Chiang, Chin-Yun; Lai, Ping-Tung; Lee, Chia-Lun; Fang, Sz-Ming

2016-01-01

[Purpose] Bicycle saddle height is a critical factor for cycling performance and injury prevention. The present study compared the variance in cadence frequency after exercise fatigue between saddle heights with 25° and 35° knee flexion. [Methods] Two saddle heights, which were determined by setting the pedal at the bottom dead point with 35° and 25° knee flexion, were used for testing. The relative variances of the cadence frequency were calculated at the end of a 5-minute warm-up period and 5 minutes after inducing exercise fatigue. Comparison of the absolute values of the cadence frequency under the two saddle heights revealed a difference in pedaling efficiency. [Results] Five minutes after inducing exercise fatigue, the relative variances of the cadence frequency for the saddle height with 35° knee flexion was higher than that for the saddle height with 25° knee flexion. [Conclusion] The current finding demonstrated that a saddle height with 25° knee flexion is more appropriate for cyclists than a saddle height with 35° knee flexion. PMID:27065522
Above Saddle-Point Regions of Order in a Sea of Chaos in the Vibrational Dynamics of KCN.

PubMed

Párraga, H; Arranz, F J; Benito, R M; Borondo, F

2018-04-05

The dynamical characteristics of a region of regular vibrational motion in the sea of chaos above the saddle point corresponding to the linear C-N-K configuration is examined in detail. To explain the origin of this regularity, the associated phase space structures were characterized using suitably defined Poincaré surfaces of section, identifying the different resonances between the stretching and bending modes, as a function of excitation energy. The corresponding topology is elucidated by means of periodic orbit analysis.
Topological phase diagram and saddle point singularity in a tunable topological crystalline insulator

DOE PAGES

Neupane, Madhab; Xu, Su-Yang; Sankar, R.; ...

2015-08-20

Here we report the evolution of the surface electronic structure and surface material properties of a topological crystalline insulator (TCI), Pb 1more » $${-}$$xSnxSe, as a function of various material parameters including composition x, temperature T , and crystal structure. Our spectroscopic data demonstrate the electronic ground-state condition for the saddle point singularity, the tunability of surface chemical potential, and the surface states’ response to circularly polarized light. Our results show that each material parameter can tune the system between the trivial and topological phase in a distinct way, unlike that seen in Bi 2Se 3 and related compounds, leading to a rich topological phase diagram. Our systematic studies of the TCI Pb 1$${-}$$xSnxSe are a valuable materials guide to realize new topological phenomena.« less
Treatment outcomes of saddle nose correction.

PubMed

Hyun, Sang Min; Jang, Yong Ju

2013-01-01

Many valuable classification schemes for saddle nose have been suggested that integrate clinical deformity and treatment; however, there is no consensus regarding the most suitable classification and surgical method for saddle nose correction. To present clinical characteristics and treatment outcome of saddle nose deformity and to propose a modified classification system to better characterize the variety of different saddle nose deformities. The retrospective study included 91 patients who underwent rhinoplasty for correction of saddle nose from April 1, 2003, through December 31, 2011, with a minimum follow-up of 8 months. Saddle nose was classified into 4 types according to a modified classification. Aesthetic outcomes were classified as excellent, good, fair, or poor. Patients underwent minor cosmetic concealment by dorsal augmentation (n = 8) or major septal reconstruction combined with dorsal augmentation (n = 83). Autologous costal cartilages were used in 40 patients (44%), and homologous costal cartilages were used in 5 patients (6%). According to postoperative assessment, 29 patients had excellent, 42 patients had good, 18 patients had fair, and 2 patients had poor aesthetic outcomes. No statistical difference in surgical outcome according to saddle nose classification was observed. Eight patients underwent revision rhinoplasty, owing to recurrence of saddle, wound infection, or warping of the costal cartilage for dorsal augmentation. We introduce a modified saddle nose classification scheme that is simpler and better able to characterize different deformities. Among 91 patients with saddle nose, 20 (22%) had unsuccessful outcomes (fair or poor) and 8 (9%) underwent subsequent revision rhinoplasty. Thus, management of saddle nose deformities remains challenging. 4.
Integrability and Linearizability of the Lotka-Volterra System with a Saddle Point with Rational Hyperbolicity Ratio

NASA Astrophysics Data System (ADS)

Gravel, Simon; Thibault, Pierre

In this paper, we consider normalizability, integrability and linearizability properties of the Lotka-Volterra system in the neighborhood of a singular point with eigenvalues 1 and - λ. The results are obtained by generalizing and expanding two methods already known: the power expansion of the first integral or of the linearizing transformation and the transformation of the saddle into a node. With these methods we find conditions that are valid for λ∈ R+ or λ∈ Q. These conditions will allow us to find all the integrable and linearizable systems for λ= {p}/{2} and {2}/{p} with p∈ N+.

A hierarchical transition state search algorithm

NASA Astrophysics Data System (ADS)

del Campo, Jorge M.; Köster, Andreas M.

2008-07-01

A hierarchical transition state search algorithm is developed and its implementation in the density functional theory program deMon2k is described. This search algorithm combines the double ended saddle interpolation method with local uphill trust region optimization. A new formalism for the incorporation of the distance constrain in the saddle interpolation method is derived. The similarities between the constrained optimizations in the local trust region method and the saddle interpolation are highlighted. The saddle interpolation and local uphill trust region optimizations are validated on a test set of 28 representative reactions. The hierarchical transition state search algorithm is applied to an intramolecular Diels-Alder reaction with several internal rotors, which makes automatic transition state search rather challenging. The obtained reaction mechanism is discussed in the context of the experimentally observed product distribution.
27 CFR 9.203 - Saddle Rock-Malibu.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Saddle Rock-Malibu. 9.203... Saddle Rock-Malibu. (a) Name. The name of the viticultural area described in this section is “Saddle Rock-Malibu”. For purposes of part 4 of this chapter, “Saddle Rock-Malibu” is a term of viticultural...
27 CFR 9.203 - Saddle Rock-Malibu.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Saddle Rock-Malibu. 9.203... Saddle Rock-Malibu. (a) Name. The name of the viticultural area described in this section is “Saddle Rock-Malibu”. For purposes of part 4 of this chapter, “Saddle Rock-Malibu” is a term of viticultural...
27 CFR 9.203 - Saddle Rock-Malibu.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Saddle Rock-Malibu. 9.203... Saddle Rock-Malibu. (a) Name. The name of the viticultural area described in this section is “Saddle Rock-Malibu”. For purposes of part 4 of this chapter, “Saddle Rock-Malibu” is a term of viticultural...
27 CFR 9.203 - Saddle Rock-Malibu.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Saddle Rock-Malibu. 9.203... Saddle Rock-Malibu. (a) Name. The name of the viticultural area described in this section is “Saddle Rock-Malibu”. For purposes of part 4 of this chapter, “Saddle Rock-Malibu” is a term of viticultural...
27 CFR 9.203 - Saddle Rock-Malibu.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Saddle Rock-Malibu. 9.203... Saddle Rock-Malibu. (a) Name. The name of the viticultural area described in this section is “Saddle Rock-Malibu”. For purposes of part 4 of this chapter, “Saddle Rock-Malibu” is a term of viticultural...
Model reduction method using variable-separation for stochastic saddle point problems

NASA Astrophysics Data System (ADS)

Jiang, Lijian; Li, Qiuqi

2018-02-01

In this paper, we consider a variable-separation (VS) method to solve the stochastic saddle point (SSP) problems. The VS method is applied to obtain the solution in tensor product structure for stochastic partial differential equations (SPDEs) in a mixed formulation. The aim of such a technique is to construct a reduced basis approximation of the solution of the SSP problems. The VS method attempts to get a low rank separated representation of the solution for SSP in a systematic enrichment manner. No iteration is performed at each enrichment step. In order to satisfy the inf-sup condition in the mixed formulation, we enrich the separated terms for the primal system variable at each enrichment step. For the SSP problems by regularization or penalty, we propose a more efficient variable-separation (VS) method, i.e., the variable-separation by penalty method. This can avoid further enrichment of the separated terms in the original mixed formulation. The computation of the variable-separation method decomposes into offline phase and online phase. Sparse low rank tensor approximation method is used to significantly improve the online computation efficiency when the number of separated terms is large. For the applications of SSP problems, we present three numerical examples to illustrate the performance of the proposed methods.
Flood-inundation maps for the Saddle River from Upper Saddle River Borough to Saddle River Borough, New Jersey, 2013

USGS Publications Warehouse

Watson, Kara M.; Hoppe, Heidi L.

2013-01-01

Digital flood-inundation maps for a 4.1-mile reach of the Saddle River from 0.6 miles downstream from the New Jersey-New York State boundary in Upper Saddle River Borough to 0.2 miles downstream from the East Allendale Road bridge in Saddle River Borough, New Jersey, were created by the U.S. Geological Survey (USGS) in cooperation with the New Jersey Department of Environmental Protection (NJDEP). The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to select water levels (stages) at the USGS streamgage 01390450, Saddle River at Upper Saddle River, New Jersey. Current conditions for estimating near real-time areas of inundation using USGS streamgage information may be obtained on the Internet at http://waterdata.usgs.gov/nwis/uv?site_no=01390450. The National Weather Service (NWS) forecasts flood hydrographs at many places that are often collocated with USGS streamgages. NWS-forecasted peak-stage information may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. In this study, flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated by using the most current stage-discharge relations (in effect March 2013) at USGS streamgage 01390450, Saddle River at Upper Saddle River, New Jersey, and documented high-water marks from recent floods. The hydraulic model was then used to determine eight water-surface profiles for flood stages at 0.5-foot (ft) intervals referenced to the streamgage datum, North American Vertical Datum of 1988 (NAVD 88), and ranging from bankfull, 0.5 ft below NWS Action Stage, to the upper extent of the stage-discharge rating which is approximately 1 ft higher than the highest recorded water level at the streamgage. Action Stage is the stage which when reached
A new preconditioner update strategy for the solution of sequences of linear systems in structural mechanics: application to saddle point problems in elasticity

NASA Astrophysics Data System (ADS)

Mercier, Sylvain; Gratton, Serge; Tardieu, Nicolas; Vasseur, Xavier

2017-12-01

Many applications in structural mechanics require the numerical solution of sequences of linear systems typically issued from a finite element discretization of the governing equations on fine meshes. The method of Lagrange multipliers is often used to take into account mechanical constraints. The resulting matrices then exhibit a saddle point structure and the iterative solution of such preconditioned linear systems is considered as challenging. A popular strategy is then to combine preconditioning and deflation to yield an efficient method. We propose an alternative that is applicable to the general case and not only to matrices with a saddle point structure. In this approach, we consider to update an existing algebraic or application-based preconditioner, using specific available information exploiting the knowledge of an approximate invariant subspace or of matrix-vector products. The resulting preconditioner has the form of a limited memory quasi-Newton matrix and requires a small number of linearly independent vectors. Numerical experiments performed on three large-scale applications in elasticity highlight the relevance of the new approach. We show that the proposed method outperforms the deflation method when considering sequences of linear systems with varying matrices.
Why do galactic spins flip in the cosmic web? A Theory of Tidal Torques near saddles

NASA Astrophysics Data System (ADS)

Pichon, Christophe; Codis, Sandrine; Pogosyan, Dmitry; Dubois, Yohan; Desjacques, Vincent; Devriendt, Julien

2016-10-01

Filaments of the cosmic web drive spin acquisition of disc galaxies. The point process of filament-type saddle represent best this environment and can be used to revisit the Tidal Torque Theory in the context of an anisotropic peak (saddle) background split. The constrained misalignment between the tidal tensor and the Hessian of the density field generated in the vicinity of filament saddle points simply explains the corresponding transverse and longitudinal point-reflection symmetric geometry of spin distribution. It predicts in particular an azimuthal orientation of the spins of more massive galaxies and spin alignment with the filament for less massive galaxies. Its scale dependence also allows us to relate the transition mass corresponding to the alignment of dark matter halos' spin relative to the direction of their neighboring filament to this geometry, and to predict accordingly it's scaling with the mass of non linearity, as was measured in simulations.
Limit Cycle Bifurcations Near a Piecewise Smooth Generalized Homoclinic Loop with a Saddle-Fold Point

NASA Astrophysics Data System (ADS)

Liang, Feng; Wang, Dechang

In this paper, we suppose that a planar piecewise Hamiltonian system, with a straight line of separation, has a piecewise generalized homoclinic loop passing through a Saddle-Fold point, and assume that there exists a family of piecewise smooth periodic orbits near the loop. By studying the asymptotic expansion of the first order Melnikov function corresponding to the period annulus, we obtain the formulas of the first six coefficients in the expansion, based on which, we provide a lower bound for the maximal number of limit cycles bifurcated from the period annulus. As applications, two concrete systems are considered. Especially, the first one reveals that a quadratic piecewise Hamiltonian system can have five limit cycles near a generalized homoclinic loop under a quadratic piecewise smooth perturbation. Compared with the smooth case [Horozov & Iliev, 1994; Han et al., 1999], three more limit cycles are found.
36 CFR 34.10 - Saddle and pack animals.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Saddle and pack animals. 34... INTERIOR EL PORTAL ADMINISTRATIVE SITE REGULATIONS § 34.10 Saddle and pack animals. The use of saddle and pack animals is prohibited without a permit from the Superintendent. ...
36 CFR 34.10 - Saddle and pack animals.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Saddle and pack animals. 34... INTERIOR EL PORTAL ADMINISTRATIVE SITE REGULATIONS § 34.10 Saddle and pack animals. The use of saddle and pack animals is prohibited without a permit from the Superintendent. ...
36 CFR 34.10 - Saddle and pack animals.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Saddle and pack animals. 34... INTERIOR EL PORTAL ADMINISTRATIVE SITE REGULATIONS § 34.10 Saddle and pack animals. The use of saddle and pack animals is prohibited without a permit from the Superintendent. ...
36 CFR 34.10 - Saddle and pack animals.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Saddle and pack animals. 34... INTERIOR EL PORTAL ADMINISTRATIVE SITE REGULATIONS § 34.10 Saddle and pack animals. The use of saddle and pack animals is prohibited without a permit from the Superintendent. ...
36 CFR 34.10 - Saddle and pack animals.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Saddle and pack animals. 34... INTERIOR EL PORTAL ADMINISTRATIVE SITE REGULATIONS § 34.10 Saddle and pack animals. The use of saddle and pack animals is prohibited without a permit from the Superintendent. ...
46 CFR 64.29 - Tank saddles.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Tank saddles. 64.29 Section 64.29 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.29 Tank saddles. If a tank is not completely supported by a framework...
46 CFR 64.29 - Tank saddles.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Tank saddles. 64.29 Section 64.29 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.29 Tank saddles. If a tank is not completely supported by a framework...
46 CFR 64.29 - Tank saddles.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Tank saddles. 64.29 Section 64.29 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.29 Tank saddles. If a tank is not completely supported by a framework...
46 CFR 64.29 - Tank saddles.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Tank saddles. 64.29 Section 64.29 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.29 Tank saddles. If a tank is not completely supported by a framework...

46 CFR 64.29 - Tank saddles.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Tank saddles. 64.29 Section 64.29 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.29 Tank saddles. If a tank is not completely supported by a framework...
The Taylor saddle effacement: a new technique for correction of saddle nose deformity.

PubMed

Taylor, S Mark; Rigby, Matthew H

2008-02-01

To describe a novel technique, the Taylor saddle effacement (TSE), for correction of saddle nose deformity using autologous grafts from the lower lateral cartilages. A prospective evaluation of six patients, all of whom had the TSE performed. Photographs were taken in combination with completion of a rhinoplasty outcomes questionnaire preoperatively and at 6 months. The questionnaire included a visual analogue scale (VAS) of nasal breathing and a rhinoplasty outcomes evaluation (ROE) of nasal function and esthetics. All six patients had improvement in both their global nasal airflow on the VAS and on their ROE that was statistically significant. The mean preoperative VAS score was 5.8 compared with our postoperative mean of 8.5 of a possible 10. Mean ROE scores improved from 34.7 to 85.5. At 6 months, all patients felt that their nasal appearance had improved. The TSE is a simple and reliable technique for correction of saddle nose deformity. This prospective study has demonstrated improvement in both nasal function and esthetics when it is employed.
Saddled Prominent

Treesearch

Peter A. Rush; Douglas C. Allen

1987-01-01

The saddled prominent, Heterocampa guttivitta (Walker), defoliates hardwoods in the Northeastern United States and Southeastern Canada. Outbreaks of this native insect have occurred in the United States and Canada at intervals of approximately 10 years since they were first recorded in the early 1900's. Populations, characterized by their instability, build...
Deconstructing zero: resurgence, supersymmetry and complex saddles

DOE PAGES

Dunne, Gerald V.; Ünsal, Mithat

2016-12-01

We explain how a vanishing, or truncated, perturbative expansion, such as often arises in semi-classically tractable supersymmetric theories, can nevertheless be related to fluctuations about non-perturbative sectors via resurgence. We also demonstrate that, in the same class of theories, the vanishing of the ground state energy (unbroken supersymmetry) can be attributed to the cancellation between a real saddle and a complex saddle (with hidden topological angle π), and positivity of the ground state energy (broken supersymmetry) can be interpreted as the dominance of complex saddles. In either case, despite the fact that the ground state energy is zero to allmore » orders in perturbation theory, all orders of fluctuations around non-perturbative saddles are encoded in the perturbative E (N, g). Finally, we illustrate these ideas with examples from supersymmetric quantum mechanics and quantum field theory.« less
Stellarator Saddle Coils

NASA Astrophysics Data System (ADS)

Boozer, Allen H.

1999-11-01

Modern stellarators are designed using J. Nuehrenberg’s method of varying Fourier coefficients in the shape of the plasma boundary to maximize a target function. The matrix of second derivatives of the target function at the optimum determines a quality matrix. This matrix gives the degradation in the quality of the configuration as the normal magnetic field is varied on a control surface, which lies on or outside the plasma surface. The task is finding saddle coils that produce the desired configuration in the presence of a given toroidal field. An eigenvector of the quality matrix can be important for two reasons: (1) the normal field that must be produced by the saddles is large or (2) the eigenvalue is large (an island-causing resonant perturbation). The rank of the important part of the quality matrix is the number of important eigenvectors. The current in each saddle coil produces a normal field on the control surface, which can be described by an inductance matrix. The relevant part of the inductance matrix has large eigenvalues. The coils can produce the configuration if the rank of the important part of the quality matrix and its product with the relevant part of the inductance matrix are the same. Existing coil design codes, pioneered by P. Merkel, approximate the quality matrix by the unit matrix. Stellarator flexibility could be enhanced by using a more realistic quality matrix and by using trim coils to balance large eigenvalues.
The Geometry of Quadratic Polynomial Differential Systems with a Finite and an Infinite Saddle-Node (C)

NASA Astrophysics Data System (ADS)

Artés, Joan C.; Rezende, Alex C.; Oliveira, Regilene D. S.

Planar quadratic differential systems occur in many areas of applied mathematics. Although more than one thousand papers have been written on these systems, a complete understanding of this family is still missing. Classical problems, and in particular, Hilbert's 16th problem [Hilbert, 1900, 1902], are still open for this family. Our goal is to make a global study of the family QsnSN of all real quadratic polynomial differential systems which have a finite semi-elemental saddle-node and an infinite saddle-node formed by the collision of two infinite singular points. This family can be divided into three different subfamilies, all of them with the finite saddle-node in the origin of the plane with the eigenvectors on the axes and with the eigenvector associated with the zero eigenvalue on the horizontal axis and (A) with the infinite saddle-node in the horizontal axis, (B) with the infinite saddle-node in the vertical axis and (C) with the infinite saddle-node in the bisector of the first and third quadrants. These three subfamilies modulo the action of the affine group and time homotheties are three-dimensional and we give the bifurcation diagram of their closure with respect to specific normal forms, in the three-dimensional real projective space. The subfamilies (A) and (B) have already been studied [Artés et al., 2013b] and in this paper we provide the complete study of the geometry of the last family (C). The bifurcation diagram for the subfamily (C) yields 371 topologically distinct phase portraits with and without limit cycles for systems in the closure /line{QsnSN(C)} within the representatives of QsnSN(C) given by a chosen normal form. Algebraic invariants are used to construct the bifurcation set. The phase portraits are represented on the Poincaré disk. The bifurcation set of /line{QsnSN(C)} is not only algebraic due to the presence of some surfaces found numerically. All points in these surfaces correspond to either connections of separatrices, or the
Cauda equina syndrome versus saddle embolism.

PubMed

Shaw, A; Anwar, H; Targett, J; Lafferty, K

2008-09-01

We discuss a case of saddle embolism with a clinical presentation similar to cauda equina syndrome in a 79-year-old woman with a history of ischaemic heart disease. Saddle embolus is very rare but one of an array of visceral causes for back and leg pain. This case highlights diagnostic difficulties, particularly in patients with multiple disorders. A high index of suspicion for vascular conditions must be exercised in cases of arterial dysfunction presenting with back pain.
Identifying Septal Support Reconstructions for Saddle Nose Deformity: The Cakmak Algorithm.

PubMed

Cakmak, Ozcan; Emre, Ismet Emrah; Ozkurt, Fazil Emre

2015-01-01

The saddle nose deformity is one of the most challenging problems in nasal surgery with a less predictable and reproducible result than other nasal procedures. The main feature of this deformity is loss of septal support with both functional and aesthetic implications. Most reports on saddle nose have focused on aesthetic improvement and neglected the reestablishment of septal support to improve airway. To explain how the Cakmak algorithm, an algorithm that describes various fixation techniques and grafts in different types of saddle nose deformities, aids in identifying saddle nose reconstructions that restore supportive nasal framework and provide the aesthetic improvements typically associated with procedures to correct saddle nose deformities. This algorithm presents septal support reconstruction of patients with saddle nose deformity based on the experience of the senior author in 206 patients with saddle nose deformity. Preoperative examination, intraoperative assessment, reconstruction techniques, graft materials, and patient evaluation of aesthetic success were documented, and 4 different types of saddle nose deformities were defined. The Cakmak algorithm classifies varying degrees of saddle nose deformity from type 0 to type 4 and helps identify the most appropriate surgical procedure to restore the supportive nasal framework and aesthetic dorsum. Among the 206 patients, 110 women and 96 men, mean (range) age was 39.7 years (15-68 years), and mean (range) of follow-up was 32 months (6-148 months). All but 12 patients had a history of previous nasal surgeries. Application of the Cakmak algorithm resulted in 36 patients categorized with type 0 saddle nose deformities; 79, type 1; 50, type 2; 20, type 3a; 7, type 3b; and 14, type 4. Postoperative photographs showed improvement of deformities, and patient surveys revealed aesthetic improvement in 201 patients and improvement in nasal breathing in 195 patients. Three patients developed postoperative infection
On the Use of the Main-sequence Knee (Saddle) to Measure Globular Cluster Ages

NASA Astrophysics Data System (ADS)

Saracino, S.; Dalessandro, E.; Ferraro, F. R.; Lanzoni, B.; Origlia, L.; Salaris, M.; Pietrinferni, A.; Geisler, D.; Kalirai, J. S.; Correnti, M.; Cohen, R. E.; Mauro, F.; Villanova, S.; Moni Bidin, C.

2018-06-01

In this paper, we review the operational definition of the so-called main-sequence knee (MS-knee), a feature in the color-magnitude diagram (CMD) occurring at the low-mass end of the MS. The magnitude of this feature is predicted to be independent of age at fixed chemical composition. For this reason, its difference in magnitude with respect to the MS turn-off (MS-TO) point has been suggested as a possible diagnostic to estimate absolute globular cluster (GC) ages. We first demonstrate that the operational definition of the MS-knee currently adopted in the literature refers to the inflection point of the MS (which we here more appropriately named MS-saddle), a feature that is well distinct from the knee and which cannot be used as its proxy. The MS-knee is only visible in near-infrared CMDs, while the MS-saddle can be also detected in optical–NIR CMDs. By using different sets of isochrones, we then demonstrate that the absolute magnitude of the MS-knee varies by a few tenths of a dex from one model to another, thus showing that at the moment stellar models may not capture the full systematic error in the method. We also demonstrate that while the absolute magnitude of the MS-saddle is almost coincident in different models, it has a systematic dependence on the adopted color combinations which is not predicted by stellar models. Hence, it cannot be used as a reliable reference for absolute age determination. Moreover, when statistical and systematic uncertainties are properly taken into account, the difference in magnitude between the MS-TO and the MS-saddle does not provide absolute ages with better accuracy than other methods like the MS-fitting.
MIT-Skywalker: Evaluating comfort of bicycle/saddle seat.

PubMed

Goncalves, Rogerio S; Hamilton, Taya; Daher, Ali R; Hirai, Hiroaki; Krebs, Hermano I

2017-07-01

The MIT-Skywalker is a robotic device developed for the rehabilitation of gait and balance after a neurological injury. This device has been designed based on the concept of a passive walker and provides three distinct training modes: discrete movement, rhythmic movement, and balance training. In this paper, we present our efforts to evaluate the comfort of a bicycle/saddle seat design for the system's novel actuated body weight support device. We employed different bicycle and saddle seats and evaluated comfort using objective and subjective measures. Here we will summarize the results obtained from a study of fifteen healthy subjects and one stroke patient that led to the selection of a saddle seat design for the MIT-Skywalker.
Rotating Saddle Paul Trap.

ERIC Educational Resources Information Center

Rueckner, Wolfgang; And Others

1995-01-01

Describes a demonstration in which a ball is placed in an unstable position on a saddle shape. The ball becomes stable when it is rotated above some threshold angular velocity. The demonstration is a mechanical analog of confining a particle in a "Paul Trap". (DDR)
19 CFR 148.32 - Vehicles, aircraft, boats, teams and saddle horses taken abroad.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 19 Customs Duties 2 2013-04-01 2013-04-01 false Vehicles, aircraft, boats, teams and saddle horses... for Returning Residents § 148.32 Vehicles, aircraft, boats, teams and saddle horses taken abroad. (a) Admission free of duty. Automobiles and other vehicles, aircraft, boats, teams and saddle horses, together...
19 CFR 148.32 - Vehicles, aircraft, boats, teams and saddle horses taken abroad.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 2 2010-04-01 2010-04-01 false Vehicles, aircraft, boats, teams and saddle horses... for Returning Residents § 148.32 Vehicles, aircraft, boats, teams and saddle horses taken abroad. (a) Admission free of duty. Automobiles and other vehicles, aircraft, boats, teams and saddle horses, together...
19 CFR 148.32 - Vehicles, aircraft, boats, teams and saddle horses taken abroad.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 19 Customs Duties 2 2014-04-01 2014-04-01 false Vehicles, aircraft, boats, teams and saddle horses... for Returning Residents § 148.32 Vehicles, aircraft, boats, teams and saddle horses taken abroad. (a) Admission free of duty. Automobiles and other vehicles, aircraft, boats, teams and saddle horses, together...
19 CFR 148.32 - Vehicles, aircraft, boats, teams and saddle horses taken abroad.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 19 Customs Duties 2 2012-04-01 2012-04-01 false Vehicles, aircraft, boats, teams and saddle horses... for Returning Residents § 148.32 Vehicles, aircraft, boats, teams and saddle horses taken abroad. (a) Admission free of duty. Automobiles and other vehicles, aircraft, boats, teams and saddle horses, together...
19 CFR 148.32 - Vehicles, aircraft, boats, teams and saddle horses taken abroad.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 19 Customs Duties 2 2011-04-01 2011-04-01 false Vehicles, aircraft, boats, teams and saddle horses... for Returning Residents § 148.32 Vehicles, aircraft, boats, teams and saddle horses taken abroad. (a) Admission free of duty. Automobiles and other vehicles, aircraft, boats, teams and saddle horses, together...
Zero-point Energy is Needed in Molecular Dynamics Calculations to Access the Saddle Point for H+HCN→H2CN* and cis/trans-HCNH* on a New Potential Energy Surface.

PubMed

Wang, Xiaohong; Bowman, Joel M

2013-02-12

We calculate the probabilities for the association reactions H+HCN→H2CN* and cis/trans-HCNH*, using quasiclassical trajectory (QCT) and classical trajectory (CT) calculations, on a new global ab initio potential energy surface (PES) for H2CN including the reaction channels. The surface is a linear least-squares fit of roughly 60 000 CCSD(T)-F12b/aug-cc-pVDZ electronic energies, using a permutationally invariant basis with Morse-type variables. The reaction probabilities are obtained at a variety of collision energies and impact parameters. Large differences in the threshold energies in the two types of dynamics calculations are traced to the absence of zero-point energy in the CT calculations. We argue that the QCT threshold energy is the realistic one. In addition, trajectories find a direct pathway to trans-HCNH, even though there is no obvious transition state (TS) for this pathway. Instead the saddle point (SP) for the addition to cis-HCNH is evidently also the TS for direct formation of trans-HCNH.
[The mechanical behavior and biocompatibility of different modern ideas of partial fixed free-end saddle dentures].

PubMed

Lubespere, A; Lebig, A; Jourdan, P

1992-01-01

This research is aimed to check the mechanical holding and the biocompatibility at various conceptions of removable partial dentures with free saddles, constituted from satellite alloys. As a matter of fact, the duality of the supporting surface in this kind of dental prosthesis sets biological problems, that one must try to sort out in the best way. It consists of three in vitro experimentations to point out the type or the types of framework answering in the best way to biomechanical and biological requirements. The very same equipment has been used on that three experimentations adapting it to the needs. It's "a machine to overdrive", imagined into the building of "L'Ecole supérieure d'Aéronautique de Toulouse"; this machine is made of an electric engine with an axis of rotation, of two speed reducers giving a motion, of one turn by second, of a knee-joint converting a rotary motion to an alternating motion, of a lever-arm enclosing supporting the weights, of a needle with a foam point which secure the saddles or the strategic zones, of two supporting mandibular and maxillary framework resin patterns, and on the areas representing the osteo-mucosa support capped uniformly with a compressible silicone material of on millimetre thick, of one dynamometer and of an accurate comparator to check the strength used, and the displacement tested zones. The first part consists in testing the amplitude of the saddle displacement and the mobilization of strategic joining areas from various frameworks used. So we can infer the impact on the mucosa during the function. That is why six types of frameworks have been achieved in Wironit satellite alloy showing mechanical qualities admitted to be excellent and to be subject to very accurate experiment conditions with 30 Kz strength (Lundeen and Gibbs, 1982). The results are interpreted through the reading of histograms which X-AXIS represent the points where motions have been located and the Y-AXIS represent the motion at 1
Chaos in driven Alfvén systems: unstable periodic orbits and chaotic saddles

NASA Astrophysics Data System (ADS)

Chian, A. C.-L.; Santana, W. M.; Rempel, E. L.; Borotto, F. A.; Hada, T.; Kamide, Y.

2007-01-01

The chaotic dynamics of Alfvén waves in space plasmas governed by the derivative nonlinear Schrödinger equation, in the low-dimensional limit described by stationary spatial solutions, is studied. A bifurcation diagram is constructed, by varying the driver amplitude, to identify a number of nonlinear dynamical processes including saddle-node bifurcation, boundary crisis, and interior crisis. The roles played by unstable periodic orbits and chaotic saddles in these transitions are analyzed, and the conversion from a chaotic saddle to a chaotic attractor in these dynamical processes is demonstrated. In particular, the phenomenon of gap-filling in the chaotic transition from weak chaos to strong chaos via an interior crisis is investigated. A coupling unstable periodic orbit created by an explosion, within the gaps of the chaotic saddles embedded in a chaotic attractor following an interior crisis, is found numerically. The gap-filling unstable periodic orbits are responsible for coupling the banded chaotic saddle (BCS) to the surrounding chaotic saddle (SCS), leading to crisis-induced intermittency. The physical relevance of chaos for Alfvén intermittent turbulence observed in the solar wind is discussed.
Featured Partner: Saddle Creek Logistics Services

EPA Pesticide Factsheets

This EPA fact sheet spotlights Saddle Creek Logistics as a SmartWay partner committed to sustainability in reducing greenhouse gas emissions and air pollution caused by freight transportation, partly by growing its compressed natural gas (CNG) vehicles for

Lassoing saddle splay and the geometrical control of topological defects

PubMed Central

Tran, Lisa; Lavrentovich, Maxim O.; Beller, Daniel A.; Li, Ningwei; Stebe, Kathleen J.; Kamien, Randall D.

2016-01-01

Systems with holes, such as colloidal handlebodies and toroidal droplets, have been studied in the nematic liquid crystal (NLC) 4-cyano-4′-pentylbiphenyl (5CB): Both point and ring topological defects can occur within each hole and around the system while conserving the system’s overall topological charge. However, what has not been fully appreciated is the ability to manipulate the hole geometry with homeotropic (perpendicular) anchoring conditions to induce complex, saddle-like deformations. We exploit this by creating an array of holes suspended in an NLC cell with oriented planar (parallel) anchoring at the cell boundaries. We study both 5CB and a binary mixture of bicyclohexane derivatives (CCN-47 and CCN-55). Through simulations and experiments, we study how the bulk saddle deformations of each hole interact to create defect structures, including an array of disclination lines, reminiscent of those found in liquid-crystal blue phases. The line locations are tunable via the NLC elastic constants, the cell geometry, and the size and spacing of holes in the array. This research lays the groundwork for the control of complex elastic deformations of varying length scales via geometrical cues in materials that are renowned in the display industry for their stability and easy manipulability. PMID:27222582
Lassoing saddle splay and the geometrical control of topological defects

NASA Astrophysics Data System (ADS)

Tran, Lisa; Lavrentovich, Maxim O.; Beller, Daniel A.; Li, Ningwei; Stebe, Kathleen J.; Kamien, Randall D.

2016-06-01

Systems with holes, such as colloidal handlebodies and toroidal droplets, have been studied in the nematic liquid crystal (NLC) 4-cyano-4'-pentylbiphenyl (5CB): Both point and ring topological defects can occur within each hole and around the system while conserving the system's overall topological charge. However, what has not been fully appreciated is the ability to manipulate the hole geometry with homeotropic (perpendicular) anchoring conditions to induce complex, saddle-like deformations. We exploit this by creating an array of holes suspended in an NLC cell with oriented planar (parallel) anchoring at the cell boundaries. We study both 5CB and a binary mixture of bicyclohexane derivatives (CCN-47 and CCN-55). Through simulations and experiments, we study how the bulk saddle deformations of each hole interact to create defect structures, including an array of disclination lines, reminiscent of those found in liquid-crystal blue phases. The line locations are tunable via the NLC elastic constants, the cell geometry, and the size and spacing of holes in the array. This research lays the groundwork for the control of complex elastic deformations of varying length scales via geometrical cues in materials that are renowned in the display industry for their stability and easy manipulability.
Basic kinematics of the saddle and rider in high-level dressage horses trotting on a treadmill.

PubMed

Byström, A; Rhodin, M; von Peinen, K; Weishaupt, M A; Roepstorff, L

2009-03-01

A comprehensive kinematic description of rider and saddle movements is not yet present in the scientific literature. To describe saddle and rider movements in a group of high-level dressage horses and riders. Seven high-level dressage horses and riders were subjected to kinematic measurements while performing collected trot on a treadmill. For analysis a rigid body model for the saddle and core rider segments, projection angles of the rider's extremities and the neck and trunk of the horse, and distances between markers selected to indicate rider position were used. For a majority of the variables measured it was possible to describe a common pattern for the group. Rotations around the transverse axis (pitch) were generally biphasic for each diagonal. During the first half of stance the saddle rotated anti-clockwise and the rider's pelvis clockwise viewed from the right and the rider's lumbar back extended. During the later part of stance and the suspension phase reverse pitch rotations were observed. Rotations of the saddle and core rider segments around the longitudinal (roll) and vertical axes (yaw) changed direction only around time of contact of each diagonal. The saddles and riders of high-level dressage horses follow a common movement pattern at collected trot. The movements of the saddle and rider are clearly related to the movements of the horse and saddle movements also seem to be influenced by the rider. Knowledge about rider and saddle movements can further our understanding of, and hence possibilities to prevent, orthopaedic injuries related to the exposure of the horse to a rider and saddle.
Reconstruction of chaotic saddles by classification of unstable periodic orbits: Kuramoto-Sivashinsky equation.

PubMed

Saiki, Yoshitaka; Yamada, Michio; Chian, Abraham C-L; Miranda, Rodrigo A; Rempel, Erico L

2015-10-01

The unstable periodic orbits (UPOs) embedded in a chaotic attractor after an attractor merging crisis (MC) are classified into three subsets, and employed to reconstruct chaotic saddles in the Kuramoto-Sivashinsky equation. It is shown that in the post-MC regime, the two chaotic saddles evolved from the two coexisting chaotic attractors before crisis can be reconstructed from the UPOs embedded in the pre-MC chaotic attractors. The reconstruction also involves the detection of the mediating UPO responsible for the crisis, and the UPOs created after crisis that fill the gap regions of the chaotic saddles. We show that the gap UPOs originate from saddle-node, period-doubling, and pitchfork bifurcations inside the periodic windows in the post-MC chaotic region of the bifurcation diagram. The chaotic attractor in the post-MC regime is found to be the closure of gap UPOs.
Update on CERN Search based on SharePoint 2013

NASA Astrophysics Data System (ADS)

Alvarez, E.; Fernandez, S.; Lossent, A.; Posada, I.; Silva, B.; Wagner, A.

2017-10-01

CERN’s enterprise Search solution “CERN Search” provides a central search solution for users and CERN service providers. A total of about 20 million public and protected documents from a wide range of document collections is indexed, including Indico, TWiki, Drupal, SharePoint, JACOW, E-group archives, EDMS, and CERN Web pages. In spring 2015, CERN Search was migrated to a new infrastructure based on SharePoint 2013. In the context of this upgrade, the document pre-processing and indexing process was redesigned and generalised. The new data feeding framework allows to profit from new functionality and it facilitates the long term maintenance of the system.
Reconstruction of chaotic saddles by classification of unstable periodic orbits: Kuramoto-Sivashinsky equation

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

Saiki, Yoshitaka, E-mail: yoshi.saiki@r.hit-u.ac.jp; Yamada, Michio; Chian, Abraham C.-L.

The unstable periodic orbits (UPOs) embedded in a chaotic attractor after an attractor merging crisis (MC) are classified into three subsets, and employed to reconstruct chaotic saddles in the Kuramoto-Sivashinsky equation. It is shown that in the post-MC regime, the two chaotic saddles evolved from the two coexisting chaotic attractors before crisis can be reconstructed from the UPOs embedded in the pre-MC chaotic attractors. The reconstruction also involves the detection of the mediating UPO responsible for the crisis, and the UPOs created after crisis that fill the gap regions of the chaotic saddles. We show that the gap UPOs originatemore » from saddle-node, period-doubling, and pitchfork bifurcations inside the periodic windows in the post-MC chaotic region of the bifurcation diagram. The chaotic attractor in the post-MC regime is found to be the closure of gap UPOs.« less
Saddle-shaped mitral valve annuloplasty rings experience lower forces compared with flat rings.

PubMed

Jensen, Morten O; Jensen, Henrik; Smerup, Morten; Levine, Robert A; Yoganathan, Ajit P; Nygaard, Hans; Hasenkam, J Michael; Nielsen, Sten L

2008-09-30

New insight into the 3D dynamic behavior of the mitral valve has prompted a reevaluation of annuloplasty ring designs. Force balance analysis indicates correlation between annulus forces and stresses in leaflets and chords. Improving this stress distribution can intuitively enhance the durability of mitral valve repair. We tested the hypothesis that saddle-shaped annuloplasty rings have superior uniform systolic force distribution compared with a nonuniform force distribution in flat annuloplasty rings. Sixteen 80-kg pigs had a flat (n=8) or saddle-shaped (n=8) mitral annuloplasty ring implanted. Mitral annulus 3D dynamic geometry was obtained with sonomicrometry before ring insertion. Strain gauges mounted on dedicated D-shaped rigid flat and saddle-shaped annuloplasty rings provided the intraoperative force distribution perpendicular to the annular plane. Average systolic annular height to commissural width ratio before ring implantation was 14.0%+/-1.6%. After flat and saddle shaped ring implantation, the annulus was fixed in the diastolic (9.0%+/-1.0%) and systolic (14.3%+/-1.3%) configuration, respectively (P<0.01). Force accumulation was seen from the anterior (0.72N+/-0.14N) and commissural annular segments (average 1.38N+/-0.27N) of the flat rings. In these segments, the difference between the 2 types of rings was statistically significant (P<0.05). The saddle-shaped annuloplasty rings did not experience forces statistically significantly larger than zero in any annular segments. Saddle-shaped annuloplasty rings provide superior uniform annular force distribution compared to flat rings and appear to represent a configuration that minimizes out-of-plane forces that could potentially be transmitted to leaflets and chords. This may have important implications for annuloplasty ring selections.
A reduction of the saddle vertical force triggers the sit-stand transition in cycling.

PubMed

Costes, Antony; Turpin, Nicolas A; Villeger, David; Moretto, Pierre; Watier, Bruno

2015-09-18

The purpose of the study was to establish the link between the saddle vertical force and its determinants in order to establish the strategies that could trigger the sit-stand transition. We hypothesized that the minimum saddle vertical force would be a critical parameter influencing the sit-stand transition during cycling. Twenty-five non-cyclists were asked to pedal at six different power outputs from 20% (1.6 ± 0.3 W kg(-1)) to 120% (9.6 ± 1.6 W kg(-1)) of their spontaneous sit-stand transition power obtained at 90 rpm. Five 6-component sensors (saddle tube, pedals and handlebars) and a full-body kinematic reconstruction were used to provide the saddle vertical force and other force components (trunk inertial force, hips and shoulders reaction forces, and trunk weight) linked to the saddle vertical force. Minimum saddle vertical force linearly decreased with power output by 87% from a static position on the bicycle (5.30 ± 0.50 N kg(-1)) to power output=120% of the sit-stand transition power (0.68 ± 0.49 N kg(-1)). This decrease was mainly explained by the increase in instantaneous pedal forces from 2.84 ± 0.58 N kg(-1) to 6.57 ± 1.02 N kg(-1) from 20% to 120% of the power output corresponding to the sit-stand transition, causing an increase in hip vertical forces from -0.17 N kg(-1) to 3.29 N kg(-1). The emergence of strategies aiming at counteracting the elevation of the trunk (handlebars and pedals pulling) coincided with the spontaneous sit-stand transition power. The present data suggest that the large decrease in minimum saddle vertical force observed at high pedal reaction forces might trigger the sit-stand transition in cycling. Copyright © 2015 Elsevier Ltd. All rights reserved.
Interactive Reference Point Procedure Based on the Conic Scalarizing Function

PubMed Central

2014-01-01

In multiobjective optimization methods, multiple conflicting objectives are typically converted into a single objective optimization problem with the help of scalarizing functions. The conic scalarizing function is a general characterization of Benson proper efficient solutions of non-convex multiobjective problems in terms of saddle points of scalar Lagrangian functions. This approach preserves convexity. The conic scalarizing function, as a part of a posteriori or a priori methods, has successfully been applied to several real-life problems. In this paper, we propose a conic scalarizing function based interactive reference point procedure where the decision maker actively takes part in the solution process and directs the search according to her or his preferences. An algorithmic framework for the interactive solution of multiple objective optimization problems is presented and is utilized for solving some illustrative examples. PMID:24723795
Exact BPF and FBP algorithms for nonstandard saddle curves.

PubMed

Yu, Hengyong; Zhao, Shiying; Ye, Yangbo; Wang, Ge

2005-11-01

A hot topic in cone-beam CT research is exact cone-beam reconstruction from a general scanning trajectory. Particularly, a nonstandard saddle curve attracts attention, as this construct allows the continuous periodic scanning of a volume-of-interest (VOI). Here we evaluate two algorithms for reconstruction from data collected along a nonstandard saddle curve, which are in the filtered backprojection (FBP) and backprojection filtration (BPF) formats, respectively. Both the algorithms are implemented in a chord-based coordinate system. Then, a rebinning procedure is utilized to transform the reconstructed results into the natural coordinate system. The simulation results demonstrate that the FBP algorithm produces better image quality than the BPF algorithm, while both the algorithms exhibit similar noise characteristics.
Non-smooth saddle-node bifurcations III: Strange attractors in continuous time

NASA Astrophysics Data System (ADS)

Fuhrmann, G.

2016-08-01

Non-smooth saddle-node bifurcations give rise to minimal sets of interesting geometry built of so-called strange non-chaotic attractors. We show that certain families of quasiperiodically driven logistic differential equations undergo a non-smooth bifurcation. By a previous result on the occurrence of non-smooth bifurcations in forced discrete time dynamical systems, this yields that within the class of families of quasiperiodically driven differential equations, non-smooth saddle-node bifurcations occur in a set with non-empty C2-interior.
Exact BPF and FBP algorithms for nonstandard saddle curves

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

Yu Hengyong; Zhao Shiying; Ye Yangbo

2005-11-15

A hot topic in cone-beam CT research is exact cone-beam reconstruction from a general scanning trajectory. Particularly, a nonstandard saddle curve attracts attention, as this construct allows the continuous periodic scanning of a volume-of-interest (VOI). Here we evaluate two algorithms for reconstruction from data collected along a nonstandard saddle curve, which are in the filtered backprojection (FBP) and backprojection filtration (BPF) formats, respectively. Both the algorithms are implemented in a chord-based coordinate system. Then, a rebinning procedure is utilized to transform the reconstructed results into the natural coordinate system. The simulation results demonstrate that the FBP algorithm produces better imagemore » quality than the BPF algorithm, while both the algorithms exhibit similar noise characteristics.« less
Forces and pressures beneath the saddle during mounting from the ground and from a raised mounting platform.

PubMed

Geutjens, C A; Clayton, H M; Kaiser, L J

2008-03-01

The objective was to use an electronic pressure mat to measure and compare forces and pressures of the saddle on a horse's back when riders mounted from the ground and with the aid of a mounting platform. Ten riders mounted a horse three times each from the ground and from a 35 cm high mounting platform in random order. Total force (summation of forces over all 256 sensors) was measured and compared at specific points on the force-time curve. Total force was usually highest as the rider's right leg was swinging upwards and was correlated with rider mass. When normalized to rider mass, total force and peak pressure were significantly higher when mounting from the ground than from a raised platform (P<0.05). The area of highest pressure was on the right side of the withers in 97% of mounting efforts, confirming the importance of the withers in stabilizing the saddle during mounting.
Paleoseismic evidence for late Holocene tectonic deformation along the Saddle mountain fault zone, Southeastern Olympic Peninsula, Washington

USGS Publications Warehouse

Barnett, Elizabeth; Sherrod, Brian; Hughes, Jonathan F.; Kelsey, Harvey M.; Czajkowski, Jessica L.; Walsh, Timothy J.; Contreras, Trevor A.; Schermer, Elizabeth R.; Carson, Robert J.

2015-01-01

Trench and wetland coring studies show that northeast‐striking strands of the Saddle Mountain fault zone ruptured the ground about 1000 years ago, generating prominent scarps. Three conspicuous subparallel fault scarps can be traced for 15 km on Light Detection and Ranging (LiDAR) imagery, traversing the foothills of the southeast Olympic Mountains: the Saddle Mountain east fault, the Saddle Mountain west fault, and the newly identified Sund Creek fault. Uplift of the Saddle Mountain east fault scarp impounded stream flow, forming Price Lake and submerging an existing forest, thereby leaving drowned stumps still rooted in place. Stratigraphy mapped in two trenches, one across the Saddle Mountain east fault and the other across the Sund Creek fault, records one and two earthquakes, respectively, as faulting juxtaposed Miocene‐age bedrock against glacial and postglacial deposits. Although the stratigraphy demonstrates that reverse motion generated the scarps, slip indicators measured on fault surfaces suggest a component of left‐lateral slip. From trench exposures, we estimate the postglacial slip rate to be 0.2 mm/yr and between 0.7 and 3.2 mm/yr during the past 3000 years. Integrating radiocarbon data from this study with earlier Saddle Mountain fault studies into an OxCal Bayesian statistical chronology model constrains the most recent paleoearthquake age of rupture across all three Saddle Mountain faults to 1170–970 calibrated years (cal B.P.), which overlaps with the nearby Mw 7.5 1050–1020 cal B.P. Seattle fault earthquake. An earlier earthquake recorded in the Sund Creek trench exposure, dates to around 3500 cal B.P. The geometry of the Saddle Mountain faults and their near‐synchronous rupture to nearby faults 1000 years ago suggest that the Saddle Mountain fault zone forms a western boundary fault along which the fore‐arc blocks migrate northward in response to margin‐parallel shortening across the Puget Lowland.
Automated search of control points in surface-based morphometry.

PubMed

Canna, Antonietta; Russo, Andrea G; Ponticorvo, Sara; Manara, Renzo; Pepino, Alessandro; Sansone, Mario; Di Salle, Francesco; Esposito, Fabrizio

2018-04-16

Cortical surface-based morphometry is based on a semi-automated analysis of structural MRI images. In FreeSurfer, a widespread tool for surface-based analyses, a visual check of gray-white matter borders is followed by the manual placement of control points to drive the topological correction (editing) of segmented data. A novel algorithm combining radial sampling and machine learning is presented for the automated control point search (ACPS). Four data sets with 3 T MRI structural images were used for ACPS validation, including raw data acquired twice in 36 healthy subjects and both raw and FreeSurfer preprocessed data of 125 healthy subjects from public databases. The unedited data from a subgroup of subjects were submitted to manual control point search and editing. The ACPS algorithm was trained on manual control points and tested on new (unseen) unedited data. Cortical thickness (CT) and fractal dimensionality (FD) were estimated in three data sets by reconstructing surfaces from both unedited and edited data, and the effects of editing were compared between manual and automated editing and versus no editing. The ACPS-based editing improved the surface reconstructions similarly to manual editing. Compared to no editing, ACPS-based and manual editing significantly reduced CT and FD in consistent regions across different data sets. Despite the extra processing of control point driven reconstructions, CT and FD estimates were highly reproducible in almost all cortical regions, albeit some problematic regions (e.g. entorhinal cortex) may benefit from different editing. The use of control points improves the surface reconstruction and the ACPS algorithm can automate their search reducing the burden of manual editing. Copyright © 2018 Elsevier Inc. All rights reserved.
Reliable Transition State Searches Integrated with the Growing String Method.

PubMed

Zimmerman, Paul

2013-07-09

The growing string method (GSM) is highly useful for locating reaction paths connecting two molecular intermediates. GSM has often been used in a two-step procedure to locate exact transition states (TS), where GSM creates a quality initial structure for a local TS search. This procedure and others like it, however, do not always converge to the desired transition state because the local search is sensitive to the quality of the initial guess. This article describes an integrated technique for simultaneous reaction path and exact transition state search. This is achieved by implementing an eigenvector following optimization algorithm in internal coordinates with Hessian update techniques. After partial convergence of the string, an exact saddle point search begins under the constraint that the maximized eigenmode of the TS node Hessian has significant overlap with the string tangent near the TS. Subsequent optimization maintains connectivity of the string to the TS as well as locks in the TS direction, all but eliminating the possibility that the local search leads to the wrong TS. To verify the robustness of this approach, reaction paths and TSs are found for a benchmark set of more than 100 elementary reactions.
Complexes and saddle point structures, vibrational frequencies and relative energies of intermediates for CH2Br + HBr «-» CH3Br + Br

NASA Astrophysics Data System (ADS)

Espinosa-Garcia, J.

Ab initio molecular orbital theory was used to study parts of the reaction between the CH2Br radical and the HBr molecule, and two possibilities were analysed: attack on the hydrogen and attack on the bromine of the HBr molecule. Optimized geometries and harmonic vibrational frequencies were calculated at the second-order Moller-Plesset perturbation theory levels, and comparison with available experimental data was favourable. Then single-point calculations were performed at several higher levels of calculation. In the attack on the hydrogen of HBr, two stationary points were located on the direct hydrogen abstraction reaction path: a very weak hydrogen bonded complex of reactants, C···HBr, close to the reactants, followed by the saddle point (SP). The effects of level of calculation (method + basis set), spin projection, zeropoint energy, thermal corrections (298K), spin-orbit coupling and basis set superposition error (BSSE) on the energy changes were analysed. Taking the reaction enthalpy (298K) as reference, agreement with experiment was obtained only when high correlation energy and large basis sets were used. It was concluded that at room temperature (i.e., with zero-point energy and thermal corrections), when the BSSE was included, the complex disappears and the activation enthalpy (298K) ranges from 0.8kcal mol-1 to 1.4kcal mol-1 above the reactants, depending on the level of calculation. It was concluded also that this result is the balance of a complicated interplay of many factors, which are affected by uncertainties in the theoretical calculations. Finally, another possible complex (X complex), which involves the alkyl radical being attracted to the halogen end of HBr (C···BrH), was explored also. It was concluded that this X complex does not exist at room temperature.
78 FR 36164 - Tongass National Forest; Ketchikan-Misty Fiords Ranger District; Alaska; Saddle Lakes Timber Sale...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-17

... District; Alaska; Saddle Lakes Timber Sale Environmental Impact Statement AGENCY: Forest Service, USDA... Notice of Intent (NOI) to prepare an Environmental Impact Statement for the Saddle Lakes Timber Sale... management plans documented with a Record of Decision or Decision Notice (reference 36 CFR part 218). This...
The effectiveness of adhesives on the retention of mandibular free end saddle partial dentures: An in vitro study.

PubMed

Quiney, Daniel; Nishio Ayre, Wayne; Milward, Paul

2017-07-01

Existing in vitro methods for testing denture adhesives do not fully replicate the complex oral geometries and environment; and in vivo methods are qualitative, prone to bias and not easily reproducible. The purpose of this study was to develop a novel, quantitative and more accurate model to test the effect of adhesives on the retentive force of mandibular free end saddle partial dentures. An in vitro model was developed based on an anatomically accurate cast of a clinical case. Experimentally, the amount of adhesive was varied (0.2g-1g) and the tensile force required for displacement was measured. Different commercially available adhesives were then tested at the optimum volume using the in vitro model. A 3D finite element model of the denture was used to assess how the forces to induce denture displacement varied according to the position of the force along the saddle length. The mass of adhesive was found to significantly alter retention forces, with 0.4-0.7g being the optimum range for this particular scenario. Use of adhesives significantly improved mandibular free end saddle partial denture retention with the worst performing adhesive increasing retention nine-fold whilst the best performing adhesive increased retention twenty three-fold. The finite element model revealed that 77% more force was required to displace the denture by positioning forces towards the mesial end of the saddle compared to the distal end. An in vitro denture adhesive model was developed, which demonstrated that mass of adhesive plays a significant role in enhancing denture retention and supported the design principle of placing as few teeth as clinically necessary on the distal end of the free end saddles. Limiting the position of teeth on free end saddles to the mesial and mid portion of the saddle will reduce displacements caused by mastication. The movement of mandibular free end saddle partial dentures can be restricted with the use of denture adhesives. Altering the mass of
Nonconvergence to Saddle Boundary Points under Perturbed Reinforcement Learning

DTIC Science & Technology

2012-12-07

of the ODE (12). Note that for some games not all stationary points of the ODE (12) are Nash equilibria. For example, if you consider the Typewriter ...B A 4, 4 2, 2 B 2, 2 3, 3 Table 1: The Typewriter Game. On the other hand, any stationary point in the interior of the probability simplex will... Typewriter Game of Table 1. We observe that it is possible for the process to converge to a pure strategy profile which is not a Nash equilibrium when Ri(α

The chaotic saddle of a three degrees of freedom scattering system reconstructed from cross-section data

NASA Astrophysics Data System (ADS)

Drótos, G.; Jung, C.

2016-06-01

The topic of this paper is hyperbolic chaotic scattering in a three degrees of freedom system. We generalize how shadows in the domain of the doubly differential cross-section are found: they are traced out by the appropriately filtered unstable manifolds of the periodic trajectories in the chaotic saddle. These shadows are related to the rainbow singularities in the doubly differential cross-section. As a result of this relation, we discover a method of how to recognize in the cross section a smoothly deformed image of the chaotic saddle, allowing the reconstruction of the symbolic dynamics of the chaotic saddle, its topology and its scaling factors.
Saddle Bag Mountain Research Natural Area: guidebook supplement 34.

Treesearch

Reid Schuller; Ronald L. Exeter

2007-01-01

This guidebook describes the Saddle Bag Mountain Research Natural Area, a 121-ha (300-ac) tract established to represent an old-growth remnant of Pacific silver fir (Abies amabilis) and western hemlock (Tsuga heterophylla) forest in the Oregon Coast Range. Pacific silver fir and noble fir (Abies procera)...
ClinicalKey 2.0: Upgrades in a Point-of-Care Search Engine.

PubMed

Huslig, Mary Ann; Vardell, Emily

2015-01-01

ClinicalKey 2.0, launched September 23, 2014, offers a mobile-friendly design with a search history feature for targeting point-of-care resources for health care professionals. Browsing is improved with searchable, filterable listings of sources highlighting new resources. ClinicalKey 2.0 improvements include more than 1,400 new Topic Pages for quick access to point-of-care content. A sample search details some of the upgrades and content options.
Saddle-nose deformity repair with microplate-adapted costal cartilage.

PubMed

Eren, Fikret; Öksüz, Sinan; Melikoğlu, Cenk; Karagöz, Hüseyin; Ülkür, Ersin

2014-08-01

Nasal deformities affecting the bone and lower two-thirds of the nose due to the loss of septal height and tip support are defined as "saddle-nose" deformity. Reconstruction of a saddle-nose deformity essentially necessitates structural grafting. This article presents an alternative approach for correction of saddle-nose deformity using a microplate and costal cartilage. The results are compared with those of the previously applied costal cartilage repair methods. Between 2004 and 2013, 16 patients were treated with costal cartilage autografts. Of these 16 patients, 7 were treated with a microplate and costal cartilage autograft combination, 4 were treated with a costal cartilage autograft and Kirschner (K)-wire, and 5 were treated with onlay costal cartilage grafts. The mean follow-up periods were 16 months for group treated with microplate-adapted autologous costal cartilage, 12 months for the group treated with K-wire and autologous costal cartilage, and 16 months for the group treated with onlay costal cartilage. The patients treated with K-wire inserted cartilages and the patients treated onlay dorsal costal cartilages encountered complications such as extrusion of the wire and warping, respectively. The seven patients treated with microplate and dorsal onlay costal cartilage graft did not experience any infection, warping, or extrusion complication. The warping tendency of the costal cartilage autograft can be efficiently prevented without a prominent complication risk by using microplate-adapted costal cartilage grafts. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .
ClinicalKey: a point-of-care search engine.

PubMed

Vardell, Emily

2013-01-01

ClinicalKey is a new point-of-care resource for health care professionals. Through controlled vocabulary, ClinicalKey offers a cross section of resources on diseases and procedures, from journals to e-books and practice guidelines to patient education. A sample search was conducted to demonstrate the features of the database, and a comparison with similar tools is presented.
On the late-time behavior of Virasoro blocks and a classification of semiclassical saddles

NASA Astrophysics Data System (ADS)

Fitzpatrick, A. Liam; Kaplan, Jared

2017-04-01

Recent work has demonstrated that black hole thermodynamics and information loss/restoration in AdS3/CFT2 can be derived almost entirely from the behavior of the Virasoro conformal blocks at large central charge, with relatively little dependence on the precise details of the CFT spectrum or OPE coefficients. Here, we elaborate on the non-perturbative behavior of Virasoro blocks by classifying all `saddles' that can contribute for arbitrary values of external and internal operator dimensions in the semiclassical large central charge limit. The leading saddles, which determine the naive semiclassical behavior of the Virasoro blocks, all decay exponentially at late times, and at a rate that is independent of internal operator dimensions. Consequently, the semiclassical contribution of a finite number of high-energy states cannot resolve a well-known version of the information loss problem in AdS3. However, we identify two infinite classes of sub-leading saddles, and one of these classes does not decay at late times.
Gentlest ascent dynamics for calculating first excited state and exploring energy landscape of Kohn-Sham density functionals.

PubMed

Li, Chen; Lu, Jianfeng; Yang, Weitao

2015-12-14

We develop the gentlest ascent dynamics for Kohn-Sham density functional theory to search for the index-1 saddle points on the energy landscape of the Kohn-Sham density functionals. These stationary solutions correspond to excited states in the ground state functionals. As shown by various examples, the first excited states of many chemical systems are given by these index-1 saddle points. Our novel approach provides an alternative, more robust way to obtain these excited states, compared with the widely used ΔSCF approach. The method can be easily generalized to target higher index saddle points. Our results also reveal the physical interest and relevance of studying the Kohn-Sham energy landscape.
Technological parameters of welding of branch saddles to polyethylene pipes at low temperatures

NASA Astrophysics Data System (ADS)

Starostin, N. P.; Vasilieva, M. A.

2017-12-01

The present paper outlines a procedure for determination of dynamics of the temperature field during the welding of the branch saddle to the polyethylene gas pipeline at ambient temperatures below the normative. The analysis is accomplished by the finite element method with the heat of the phase transition taken into account. Methods of the visualization of data sets reveal the possibility of controlling the thermal process by preheating and thermal insulation during welding of the branch saddle to the pipe at low temperatures and the possibility of obtaining the dynamics of the temperature field at which a high-quality welded joint is formed.
A Search for Point Sources of EeV Photons

NASA Astrophysics Data System (ADS)

Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; Dorosti Hasankiadeh, Q.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fernandes, M.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fox, B. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Fuji, T.; Gaior, R.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gate, F.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Islo, K.; Jandt, I.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, A. J.; Matthews, J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morello, C.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Ochilo, L.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Papenbreer, P.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Peķala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Peters, C.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Privitera, P.; Prouza, M.; Purrello, V.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Taborda, O. A.; Tapia, A.; Tartare, M.; Thao, N. T.; Theodoro, V. M.; Tiffenberg, J.; Timmermans, C.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Vlcek, B.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Whelan, B. J.; Widom, A.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Auger Collaboration102, The Pierre

2014-07-01

Measurements of air showers made using the hybrid technique developed with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for point sources of EeV photons anywhere in the exposed sky. A multivariate analysis reduces the background of hadronic cosmic rays. The search is sensitive to a declination band from -85° to +20°, in an energy range from 1017.3 eV to 1018.5 eV. No photon point source has been detected. An upper limit on the photon flux has been derived for every direction. The mean value of the energy flux limit that results from this, assuming a photon spectral index of -2, is 0.06 eV cm-2 s-1, and no celestial direction exceeds 0.25 eV cm-2 s-1. These upper limits constrain scenarios in which EeV cosmic ray protons are emitted by non-transient sources in the Galaxy.
Identification of a mutation that is associated with the saddle tan and black-and-tan phenotypes in Basset Hounds and Pembroke Welsh Corgis.

PubMed

Dreger, Dayna L; Parker, Heidi G; Ostrander, Elaine A; Schmutz, Sheila M

2013-01-01

The causative mutation for the black-and-tan (a (t) ) phenotype in dogs was previously shown to be a SINE insertion in the 5' region of Agouti Signaling Protein (ASIP). Dogs with the black-and-tan phenotype, as well as dogs with the saddle tan phenotype, genotype as a (t) /_ at this locus. We have identified a 16-bp duplication (g.1875_1890dupCCCCAGGTCAGAGTTT) in an intron of hnRNP associated with lethal yellow (RALY), which segregates with the black-and-tan phenotype in a group of 99 saddle tan and black-and-tan Basset Hounds and Pembroke Welsh Corgis. In these breeds, all dogs with the saddle tan phenotype had RALY genotypes of +/+ or +/dup, whereas dogs with the black-and-tan phenotype were homozygous for the duplication. The presence of an a (y) /_ fawn or e/e red genotype is epistatic to the +/_ saddle tan genotype. Genotypes from 10 wolves and 1 coyote indicated that the saddle tan (+) allele is the ancestral allele, suggesting that black-and-tan is a modification of saddle tan. An additional 95 dogs from breeds that never have the saddle tan phenotype have all three of the possible RALY genotypes. We suggest that a multi-gene interaction involving ASIP, RALY, MC1R, DEFB103, and a yet-unidentified modifier gene is required for expression of saddle tan.
Surface plasma source with saddle antenna radio frequency plasma generator.

PubMed

Dudnikov, V; Johnson, R P; Murray, S; Pennisi, T; Piller, C; Santana, M; Stockli, M; Welton, R

2012-02-01

A prototype RF H(-) surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA∕kW. Control experiments with H(-) beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.
View southwest of concrete saddles and flood walls for demolished ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View southwest of concrete saddles and flood walls for demolished 12-foot pipeline, on west side of West Canada Creek - Trenton Falls Hydroelectric Station, On west bank of West Canada Creek, along Trenton Fally Road, 1.25 miles north of New York Route 28, Trenton Falls, Oneida County, NY
Knee point search using cascading top-k sorting with minimized time complexity.

PubMed

Wang, Zheng; Tseng, Shian-Shyong

2013-01-01

Anomaly detection systems and many other applications are frequently confronted with the problem of finding the largest knee point in the sorted curve for a set of unsorted points. This paper proposes an efficient knee point search algorithm with minimized time complexity using the cascading top-k sorting when a priori probability distribution of the knee point is known. First, a top-k sort algorithm is proposed based on a quicksort variation. We divide the knee point search problem into multiple steps. And in each step an optimization problem of the selection number k is solved, where the objective function is defined as the expected time cost. Because the expected time cost in one step is dependent on that of the afterwards steps, we simplify the optimization problem by minimizing the maximum expected time cost. The posterior probability of the largest knee point distribution and the other parameters are updated before solving the optimization problem in each step. An example of source detection of DNS DoS flooding attacks is provided to illustrate the applications of the proposed algorithm.
High incidence of post-dural puncture headache in patients with spinal saddle block induced with Quincke needles for anorectal surgery: a randomised clinical trial.

PubMed

Schmittner, Marc D; Terboven, Tom; Dluzak, Michael; Janke, Andrea; Limmer, Marc E; Weiss, Christel; Bussen, Dieter G; Burmeister, Marc A; Beck, Grietje C

2010-06-01

Spinal saddle block represents nearly the ideal anaesthesia technique for anorectal surgery. Post-dural puncture headache (PDPH) is a dreaded complication but can be decreased by the use of non-cutting spinal needles to rates less than 1%. Though, cutting Quincke type needles are still widely used for economic reasons, leading to a higher rate of PDPH. We performed this study to demonstrate a reduction of PDPH by the use of very small 29-G compared with commonly used 25-G Quincke type spinal needles. Two hundred sixteen adult patients (male/female, 19-83 years, ASA status I-III) were randomised 1:1 to groups, in which either a 25-G or a 29-G Quincke type spinal needle was used for a spinal saddle block. The incidence of PDPH was assessed during 1 week after surgery. Thirty-nine of 216 patients developed PDPH but there was no difference between the two needle sizes (25-G, n = 18/106 vs. 29-G, n = 21/110, p = 0.6870). Women suffered significantly more from PDPH than men (23/86 vs. 16/130, p = 0.0069). Ambulatory patients had a later onset of PDPH than in-patients (24 h [0.5-72] vs. 2 h [0.2-96], p = 0.0002) and the headache was more severe in these patients (NRS 7 [2-10] vs. NRS 3 [1-8], p = 0.0009). The use of 29-G compared with 25-G Quincke needles led to no reduction of PDPH and is considerably higher compared with data from pencil-point needles. The use of non-cutting or pencil-point spinal needles should become the standard for performing spinal saddle block.
Migrated hydrocarbons in exposure of Maastrichtian nonmarine strata near Saddle Mountain, lower Cook Inlet, Alaska

USGS Publications Warehouse

LePain, D.L.; Lillis, P.G.; Helmold, K.P.; Stanley, R.G.

2012-01-01

Magoon and others (1980) described an 83-meter- (272-foot-) thick succession of Maastrichtian (Upper Cretaceous) conglomerate, sandstone, mudstone, and coal exposed on the south side of an unnamed drainage, approximately 3 kilometers (1.8 miles) east of Saddle Mountain in lower Cook Inlet (ﬁgs. 1 and 2). The initial signiﬁcance of this exposure was that it was the ﬁrst reported occurrence of nonmarine rocks of this age in outcrop in lower Cook Inlet, which helped constrain the Late Cretaceous paleogeography of the area and provided important information on the composition of latest Mesozoic sandstones in the basin. The Saddle Mountain section is thought to be an outcrop analog for Upper Cretaceous nonmarine strata penetrated in the OCS Y-0097 #1 (Raven) well, located approximately 40 kilometers (25 miles) to the south–southeast in Federal waters (ﬁg. 1). Atlantic Richﬁeld Company (ARCO) drilled the Raven well in 1980 and encountered oil-stained rocks and moveable liquid hydrocarbons between the depths of 1,760 and 3,700 feet. Completion reports on ﬁle with the Bureau of Ocean Energy Management (BOEM; formerly Bureau of Ocean Energy Management, Regulation and Enforcement, and prior to 2010, U.S. Minerals Management Service) either show ﬂow rates of zero or do not mention ﬂow rates. A ﬂuid analysis report on ﬁle with BOEM suggests that a wireline tool sampled some oil beneath a 2,010-foot diesel cushion during the ﬂ ow test of the 3,145–3,175 foot interval, but the recorded ﬂ ow rate was still zero (Kirk Sherwood, written commun., January 9, 2012). Further delineation and evaluation of the apparent accumulation was never performed and the well was plugged and abandoned. As part of a 5-year comprehensive evaluation of the geology and petroleum systems of the Cook Inlet forearc basin, the Alaska Division of Geological & Geophysical Surveys obtained a research permit from the National Park Service to access the relatively poorly understood ‘Saddle
Back in the saddle: large-deviation statistics of the cosmic log-density field

NASA Astrophysics Data System (ADS)

Uhlemann, C.; Codis, S.; Pichon, C.; Bernardeau, F.; Reimberg, P.

2016-08-01

We present a first principle approach to obtain analytical predictions for spherically averaged cosmic densities in the mildly non-linear regime that go well beyond what is usually achieved by standard perturbation theory. A large deviation principle allows us to compute the leading order cumulants of average densities in concentric cells. In this symmetry, the spherical collapse model leads to cumulant generating functions that are robust for finite variances and free of critical points when logarithmic density transformations are implemented. They yield in turn accurate density probability distribution functions (PDFs) from a straightforward saddle-point approximation valid for all density values. Based on this easy-to-implement modification, explicit analytic formulas for the evaluation of the one- and two-cell PDF are provided. The theoretical predictions obtained for the PDFs are accurate to a few per cent compared to the numerical integration, regardless of the density under consideration and in excellent agreement with N-body simulations for a wide range of densities. This formalism should prove valuable for accurately probing the quasi-linear scales of low-redshift surveys for arbitrary primordial power spectra.
Saddle clamp assembly

NASA Technical Reports Server (NTRS)

Belrose, Charles R. (Inventor)

1994-01-01

A saddle clamp assembly is presented. The assembly is comprised of a hollow cylindrical body centered about a longitudinal axis and being diametrically split into semicircular top and bottom sections. Each section has a pair of connection flanges, at opposite ends, that project radially outward. A pair of bolts are retained on the top section flanges and are threadable into nuts retained on the bottom section flanges. A base member is anchored to a central underside portion of the bottom clamp body section and has a pair of connection tabs positioned beneath the bottom clamp body section connection flanges on opposite sides of the clamp axis. A pair of bolts are retained on the base member connection tabs and are threadable into a pair of nuts retainable on a support structure. The connection tab and connection flanges on each side of the clamp body are axially offset in a manner permitting downward installation/removable tool access to the lower bolts past the connection flanges. An elongated retention tether is used to connect the top clamp body section to the balance of the clamp assembly. This prevents loss of the top clamp body section when it is removed from the bottom clamp body section.
Spike-adding in parabolic bursters: The role of folded-saddle canards

NASA Astrophysics Data System (ADS)

Desroches, Mathieu; Krupa, Martin; Rodrigues, Serafim

2016-09-01

The present work develops a new approach to studying parabolic bursting, and also proposes a novel four-dimensional canonical and polynomial-based parabolic burster. In addition to this new polynomial system, we also consider the conductance-based model of the Aplysia R15 neuron known as the Plant model, and a reduction of this prototypical biophysical parabolic burster to three variables, including one phase variable, namely the Baer-Rinzel-Carillo (BRC) phase model. Revisiting these models from the perspective of slow-fast dynamics reveals that the number of spikes per burst may vary upon parameter changes, however the spike-adding process occurs in an explosive fashion that involves special solutions called canards. This spike-adding canard explosion phenomenon is analysed by using tools from geometric singular perturbation theory in tandem with numerical bifurcation techniques. We find that the bifurcation structure persists across all considered systems, that is, spikes within the burst are incremented via the crossing of an excitability threshold given by a particular type of canard orbit, namely the true canard of a folded-saddle singularity. However there can be a difference in the spike-adding transitions in parameter space from one case to another, according to whether the process is continuous or discontinuous, which depends upon the geometry of the folded-saddle canard. Using these findings, we construct a new polynomial approximation of the Plant model, which retains all the key elements for parabolic bursting, including the spike-adding transitions mediated by folded-saddle canards. Finally, we briefly investigate the presence of spike-adding via canards in planar phase models of parabolic bursting, namely the theta model by Ermentrout and Kopell.
Solar Coronal Loop Dynamics Near the Null Point Above Active Region NOAA 2666

NASA Astrophysics Data System (ADS)

Filippov, B.

2018-06-01

We analyse observations of a saddle-like structure in the corona above the western limb of the Sun on 2017 July 18. The structure was clearly outlined by coronal loops with typical coronal temperature no more than 1 MK. The dynamics of loops showed convergence towards the centre of the saddle in the vertical direction and divergence in the horizontal direction. The event is a clear example of smooth coronal magnetic field reconnection. No heating manifestations in the reconnection region or magnetically connected areas were observed. Potential magnetic field calculations, which use as the boundary condition the SDO/HMI magnetogram taken on July 14, showed the presence of a null point at the height of 122 arcsec above the photosphere just at the centre of the saddle structure. The shape of field lines fits the fan-spine magnetic configuration above NOAA 2666.
Application of a Saddle-Type Eddy Current Sensor in Steel Ball Surface-Defect Inspection

PubMed Central

Zhong, Mingming; Xie, Fengqin; Cao, Maoyong

2017-01-01

Steel ball surface-defect inspection was performed by using a new saddle-type eddy current sensor (SECS), which included a saddle coil and a signal conditioning circuit. The saddle coil was directly wound on the steel ball’s outer bracket in a semi-circumferential direction. Driven by a friction wheel, the test steel ball rotated in a one-dimensional direction, such that the steel ball surface was fully scanned by the SECS. There were two purposes for using the SECS in the steel ball inspection system: one was to reduce the complexity of the unfolding wheel of the surface deployment mechanism, and the other was to reduce the difficulty of sensor processing and installation. Experiments were carried out on bearing steel balls in diameter of 8 mm with three types of representative and typical defects by using the SECS, and the results showed that the inspection system can detect surface defects as small as 0.05 mm in width and 0.1 mm in depth with high-repetition detection accuracy, and the detection efficiency of 5 pcs/s, which meet the requirement for inspecting ISO grade 10 bearing steel balls. The feasibility of detecting steel ball surface defects by SECS was verified. PMID:29206154

Application of a Saddle-Type Eddy Current Sensor in Steel Ball Surface-Defect Inspection.

PubMed

Zhang, Huayu; Zhong, Mingming; Xie, Fengqin; Cao, Maoyong

2017-12-05

Steel ball surface-defect inspection was performed by using a new saddle-type eddy current sensor (SECS), which included a saddle coil and a signal conditioning circuit. The saddle coil was directly wound on the steel ball's outer bracket in a semi-circumferential direction. Driven by a friction wheel, the test steel ball rotated in a one-dimensional direction, such that the steel ball surface was fully scanned by the SECS. There were two purposes for using the SECS in the steel ball inspection system: one was to reduce the complexity of the unfolding wheel of the surface deployment mechanism, and the other was to reduce the difficulty of sensor processing and installation. Experiments were carried out on bearing steel balls in diameter of 8 mm with three types of representative and typical defects by using the SECS, and the results showed that the inspection system can detect surface defects as small as 0.05 mm in width and 0.1 mm in depth with high-repetition detection accuracy, and the detection efficiency of 5 pcs/s, which meet the requirement for inspecting ISO grade 10 bearing steel balls. The feasibility of detecting steel ball surface defects by SECS was verified.
Sediment oxygen demand in the Saddle River and Salem River watersheds, New Jersey, July-August 2008

USGS Publications Warehouse

Heckathorn, Heather A.; Gibs, Jacob

2010-01-01

Many factors, such as river depth and velocity, biochemical oxygen demand, and algal productivity, as well as sediment oxygen demand, can affect the concentration of dissolved oxygen in the water column. Measurements of sediment oxygen demand, in conjunction with those of other water-column water-quality constituents, are useful for quantifying the mechanisms that affect in-stream dissolved-oxygen concentrations. Sediment-oxygen-demand rates are also needed to develop and calibrate a water-quality model being developed for the Saddle River and Salem River Basins in New Jersey to predict dissolved-oxygen concentrations. This report documents the methods used to measure sediment oxygen demand in the Saddle River and Salem River watersheds along with the rates of sediment oxygen demand that were obtained during this investigation. In July and August 2008, sediment oxygen demand was measured in situ in the Saddle River and Salem River watersheds. In the Saddle River Basin, sediment oxygen demand was measured twice at two sites and once at a third location; in the Salem River Basin, sediment oxygen demand was measured three times at two sites and once at a third location. In situ measurements of sediment oxygen demand in the Saddle River and Salem River watersheds ranged from 0.8 to 1.4 g/m2d (grams per square meter per day) and from 0.6 to 7.1 g/m2d at 20 degrees Celsius, respectively. Except at one site in this study, rates of sediment oxygen demand generally were low. The highest rate of sediment oxygen demand measured during this investigation, 7.1 g/m2d, which occurred at Courses Landing in the Salem River Basin, may be attributable to the consumption of oxygen by a large amount of organic matter (54 grams per kilogram as organic carbon) in the streambed sediments or to potential error during data collection. In general, sediment oxygen demand increased with the concentration of organic carbon in the streambed sediments. Repeated measurements made 6 to 7 days apart
Stalk Phase Formation: Effects of Dehydration and Saddle Splay Modulus

PubMed Central

Kozlovsky, Yonathan; Efrat, Avishay; Siegel, David A.; Kozlov, Michael M.

2004-01-01

One of the earliest lipid intermediates forming in the course of membrane fusion is the lipid stalk. Although many aspects of the stalk hypothesis were elaborated theoretically and confirmed by experiments it remained unresolved whether stalk formation is always an energy consuming process or if there are conditions where the stalks are energetically favorable and form spontaneously resulting in an equilibrium stalk phase. Motivated by a recent breakthrough experiments we analyze the physical factors determining the spontaneous stalk formation. We show that this process can be driven by interplay between two factors: the elastic energy of lipid monolayers including a contribution of the saddle splay deformation and the energy of hydration repulsion acting between apposing membranes. We analyze the dependence of stalk formation on the saddle splay (Gaussian) modulus of the lipid monolayers and estimate the values of this modulus based on the experimentally established phase boundary between the lamellar and the stalk phases. We suggest that fusion proteins can induce stalk formation just by bringing the membranes into close contact, and accumulating, at least locally, a sufficiently large energy of the hydration repulsion. PMID:15454446
Miocene−Pleistocene deformation of the Saddle Mountains: Implications for seismic hazard in central Washington, USA

USGS Publications Warehouse

Staisch, Lydia; Kelsey, Harvey; Sherrod, Brian; Möller, Andreas; Paces, James B.; Blakely, Richard J.; Styron, Richard

2017-01-01

The Yakima fold province, located in the backarc of the Cascadia subduction zone, is a region of active strain accumulation and deformation distributed across a series of fault-cored folds. The geodetic network in central Washington has been used to interpret large-scale N-S shortening and westward-increasing strain; however, geodetic data are unable to resolve shortening rates across individual structures in this low-strain-rate environment. Resolving fault geometries, slip rates, and timing of faulting in the Yakima fold province is critically important to seismic hazard assessment for nearby infrastructure and population centers.The Saddle Mountains anticline is one of the most prominent Yakima folds. It is unique within the Yakima fold province in that the syntectonic strata of the Ringold Formation are preserved and provide a record of deformation and drainage reorganization. Here, we present new stratigraphic columns, U-Pb zircon tephra ages, U-series caliche ages, and geophysical modeling that constrain two line-balanced and retrodeformed cross sections. These new constraints indicate that the Saddle Mountains anticline has accommodated 1.0−1.3 km of N-S shortening since 10 Ma, that shortening increases westward along the anticline, and that the average slip rate has increased 6-fold since 6.8 Ma. Provenance analysis suggests that the source terrane for the Ringold Formation was similar to that of the modern Snake River Plain. Using new slip rates and structural constraints, we calculate the strain accumulation time, interpretable as a recurrence interval, for earthquakes on the Saddle Mountains fault and find that large-magnitude earthquakes could rupture along the Saddle Mountains fault every 2−11 k.y.
Searches for point sources in the Galactic Center region

NASA Astrophysics Data System (ADS)

di Mauro, Mattia; Fermi-LAT Collaboration

2017-01-01

Several groups have demonstrated the existence of an excess in the gamma-ray emission around the Galactic Center (GC) with respect to the predictions from a variety of Galactic Interstellar Emission Models (GIEMs) and point source catalogs. The origin of this excess, peaked at a few GeV, is still under debate. A possible interpretation is that it comes from a population of unresolved Millisecond Pulsars (MSPs) in the Galactic bulge. We investigate the detection of point sources in the GC region using new tools which the Fermi-LAT Collaboration is developing in the context of searches for Dark Matter (DM) signals. These new tools perform very fast scans iteratively testing for additional point sources at each of the pixels of the region of interest. We show also how to discriminate between point sources and structural residuals from the GIEM. We apply these methods to the GC region considering different GIEMs and testing the DM and MSPs intepretations for the GC excess. Additionally, we create a list of promising MSP candidates that could represent the brightest sources of a MSP bulge population.
Cis-dicarbonyl binding at cobalt and iron porphyrins with saddle-shape conformation.

PubMed

Seufert, Knud; Bocquet, Marie-Laure; Auwärter, Willi; Weber-Bargioni, Alexander; Reichert, Joachim; Lorente, Nicolás; Barth, Johannes V

2011-02-01

Diatomic molecules attached to complexed iron or cobalt centres are important in many biological processes. In natural systems, metallotetrapyrrole units carry respiratory gases or provide sensing and catalytic functions. Conceiving synthetic model systems strongly helps to determine the pertinent chemical foundations for such processes, with recent work highlighting the importance of the prosthetic groups' conformational flexibility as an intricate variable affecting their functional properties. Here, we present simple model systems to investigate, at the single molecule level, the interaction of carbon monoxide with saddle-shaped iron- and cobalt-porphyrin conformers, which have been stabilized as two-dimensional arrays on well-defined surfaces. Using scanning tunnelling microscopy we identified a novel bonding scheme expressed in tilted monocarbonyl and cis-dicarbonyl configurations at the functional metal-macrocycle unit. Modelling with density functional theory revealed that the weakly bonded diatomic carbonyl adduct can effectively bridge specific pyrrole groups with the metal atom as a result of the pronounced saddle-shape conformation of the porphyrin cage.
[Optic method of searching for acupuncture points and channels].

PubMed

Gertsik, G Ia; Zmievskoĭ, G N; Ivantsov, V I; Sang Min Li; Iu Byiung Kim; Gil Von Iun

2001-01-01

A procedure is proposed to search for acupuncture points and channels (APC) by space-sensitive recording of optical radiation diffusely reflected by surface (dermal and hypodermal) tissues of the body. For this purpose, the body surface is probed by low-intensity infrared radiation from a laser or noncoherent (light-emitting diodes) source by using a fiber-optic multichannel sensor. It is shown that it is most advisable to apply sources at wavelengths of 840-850 and 1260-1300 nm.
Dorsal Failures: From Saddle Deformity to Pollybeak.

PubMed

Hamilton, Grant S

2018-06-01

The nasal dorsum is an important component of a rhinoplasty and may be the primary motivation for seeking surgery. The nasal dorsum is a complex three-dimensional shape that is shrouded by local anesthetic and edema during surgery. This makes an accurate assessment of the surgical changes challenging. Complications related to dorsal modification include imbalances from over- or underresection of the structures of the nasal dorsum, inadequate or overaugmentation, an open-roof deformity, pollybeak, saddle nose, inverted-V, warped cartilage, visible grafts, contour problems, graft malposition, and extrusion. This review will discuss the common problems that can occur with dorsal modification during rhinoplasty. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.
Extending the Search for Neutrino Point Sources with IceCube above the Horizon

NASA Astrophysics Data System (ADS)

Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Alba, J. L. Bazo; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bissok, M.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Botner, O.; Bradley, L.; Braun, J.; Breder, D.; Carson, M.; Castermans, T.; Chirkin, D.; Christy, B.; Clem, J.; Cohen, S.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Day, C. T.; de Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Edwards, W. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Feusels, T.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Ganugapati, R.; Gerhardt, L.; Gladstone, L.; Goldschmidt, A.; Goodman, J. A.; Gozzini, R.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gunasingha, R. M.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Hasegawa, Y.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Imlay, R. L.; Inaba, M.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kemming, N.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Knops, S.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Lauer, R.; Lehmann, R.; Lennarz, D.; Lundberg, J.; Lünemann, J.; Madsen, J.; Majumdar, P.; Maruyama, R.; Mase, K.; Matis, H. S.; McParland, C. P.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miyamoto, H.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; Ono, M.; Panknin, S.; Patton, S.; Paul, L.; de Los Heros, C. Pérez; Petrovic, J.; Piegsa, A.; Pieloth, D.; Pohl, A. C.; Porrata, R.; Potthoff, N.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Roucelle, C.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Sarkar, S.; Schatto, K.; Schlenstedt, S.; Schmidt, T.; Schneider, D.; Schukraft, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stoufer, M. C.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sullivan, G. W.; Swillens, Q.; Taboada, I.; Tamburro, A.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Terranova, C.; Tilav, S.; Toale, P. A.; Tooker, J.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Voigt, B.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Wiedemann, A.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yodh, G.; Yoshida, S.

2009-11-01

Point source searches with the IceCube neutrino telescope have been restricted to one hemisphere, due to the exclusive selection of upward going events as a way of rejecting the atmospheric muon background. We show that the region above the horizon can be included by suppressing the background through energy-sensitive cuts. This improves the sensitivity above PeV energies, previously not accessible for declinations of more than a few degrees below the horizon due to the absorption of neutrinos in Earth. We present results based on data collected with 22 strings of IceCube, extending its field of view and energy reach for point source searches. No significant excess above the atmospheric background is observed in a sky scan and in tests of source candidates. Upper limits are reported, which for the first time cover point sources in the southern sky up to EeV energies.
Saddle-shaped reticulate Nummulites from Early Oligocene rocks of Khari area, SW Kutch, India

NASA Astrophysics Data System (ADS)

Sengupta, S.; Sarkar, Sampa; Mukhopadhyay, S.

2011-04-01

Saddle-shaped reticulate Nummulites from the Early Oligocene rocks of Khari area, SW Kutch, India is reported here for the first time. Unusual shape of this Nummulites is due to the curved nature of the coiling plane, indicating space constrained postembryonic test growth. With regular development of chambers, septa and septal filaments, the saddle-shaped Nummulites constitutes the third morphotype of N. cf. fichteli Michelotti form A. Other morphotypes of the species reported earlier include inflated lenticular and conical tests. Multiple morphotypes of N. cf. fichteli form A indicates varied test growth in response to substrate conditions. Morphological variability exhibited by N. cf. fichteli form A from Kutch and some Early Oligocene reticulate Nummulites from the Far East are comparable. This faunal suite is morphologically distinct from the contemporary reticulate Nummulites of the European localities.
Stochastic Formalism for Thermally Driven Distribution Frontier: A Nonempirical Approach to the Potential Escape Problem

NASA Astrophysics Data System (ADS)

Akashi, Ryosuke; Nagornov, Yuri S.

2018-06-01

We develop a non-empirical scheme to search for the minimum-energy escape paths from the minima of the potential surface to unknown saddle points nearby. A stochastic algorithm is constructed to move the walkers up the surface through the potential valleys. This method employs only the local gradient and diagonal part of the Hessian matrix of the potential. An application to a two-dimensional model potential is presented to demonstrate the successful finding of the paths to the saddle points. The present scheme could serve as a starting point toward first-principles simulation of rare events across the potential basins free from empirical collective variables.
Detection of symmetric homoclinic orbits to saddle-centres in reversible systems

NASA Astrophysics Data System (ADS)

Yagasaki, Kazuyuki; Wagenknecht, Thomas

2006-02-01

We present a perturbation technique for the detection of symmetric homoclinic orbits to saddle-centre equilibria in reversible systems of ordinary differential equations. We assume that the unperturbed system has primary, symmetric homoclinic orbits, which may be either isolated or appear in a family, and use an idea similar to that of Melnikov’s method to detect homoclinic orbits in their neighbourhood. This technique also allows us to identify bifurcations of unperturbed or perturbed, symmetric homoclinic orbits. Our technique is of importance in applications such as nonlinear optics and water waves since homoclinic orbits to saddle-centre equilibria describe embedded solitons (ESs) in systems of partial differential equations representing physical models, and except for special cases their existence has been previously studied only numerically using shooting methods and continuation techniques. We apply the general theory to two examples, a four-dimensional system describing ESs in nonlinear optical media and a six-dimensional system which can possess a one-parameter family of symmetric homoclinic orbits in the unperturbed case. For these examples, the analysis is compared with numerical computations and an excellent agreement between both results is found.
Search for point sources of high energy neutrinos with Amanda

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

Ahrens, J.

2002-08-01

Report of search for likely point sources for neutrinos observed by the Amanda detector. Places intensity limits on observable point sources. This paper describes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector, an array of 302 photomultiplier tubes, used for the detection of Cherenkov light from upward traveling neutrino-induced muons, buried deep in ice at the South Pole. The absolute pointing accuracy and angular resolution were studied by using coincident events between the AMANDA detector and two independent telescopes on the surface, the GASP air Cherenkov telescope and the SPASE extensive air shower array. Using datamore » collected from April to October of 1997 (130.1 days of livetime), a general survey of the northern hemisphere revealed no statistically significant excess of events from any direction. The sensitivity for a flux of muon neutrinos is based on the effective detection area for through-going muons. Averaged over the Northern sky, the effective detection area exceeds 10,000 m{sup 2} for E{sub {mu}} {approx} 10 TeV. Neutrinos generated in the atmosphere by cosmic ray interactions were used to verify the predicted performance of the detector. For a source with a differential energy spectrum proportional to E{sub {nu}}{sup -2} and declination larger than +40{sup o}, we obtain E{sup 2} (dN{sub {nu}}/dE) {le} 10{sup -6} GeV cm{sup -2} s{sup -1} for an energy threshold of 10 GeV.« less
Comparison of saddle, lumbar epidural and caudal blocks on anal sphincter tone: A prospective, randomized study.

PubMed

Shon, Yoon-Jung; Huh, Jin; Kang, Sung-Sik; Bae, Seung-Kil; Kang, Ryeong-Ah; Kim, Duk-Kyung

2016-10-01

Objective To compare the effects of saddle, lumbar epidural and caudal blocks on anal sphincter tone using anorectal manometry. Methods Patients undergoing elective anorectal surgery with regional anaesthesia were divided randomly into three groups and received a saddle (SD), lumbar epidural (LE), or caudal (CD) block. Anorectal manometry was performed before and 30 min after each regional block. The degree of motor blockade of the anal sphincter was compared using the maximal resting pressure (MRP) and the maximal squeezing pressure (MSP). Results The study analysis population consisted of 49 patients (SD group, n = 18; LE group, n = 16; CD group, n = 15). No significant differences were observed in the percentage inhibition of the MRP among the three regional anaesthetic groups. However, percentage inhibition of the MSP was significantly greater in the SD group (83.6 ± 13.7%) compared with the LE group (58.4 ± 19.8%) and the CD group (47.8 ± 16.9%). In all groups, MSP was reduced significantly more than MRP after each regional block. Conclusions Saddle block was more effective than lumbar epidural or caudal block for depressing anal sphincter tone. No differences were detected between lumbar epidural and caudal blocks.
On-the-fly transition search and applications to temperature-accelerated dynamics

NASA Astrophysics Data System (ADS)

Shim, Yunsic; Amar, Jacques

2015-03-01

Temperature-accelerated dynamics (TAD) is a powerful method to study non-equilibrium processes and has been providing surprising insights for a variety of systems. While serial TAD simulations have been limited by the roughly N3 increase in the computational cost as a function of the number of atoms N in the system, recently we have shown that by carrying out parallel TAD simulations which combine spatial decomposition with our semi-rigorous synchronous sublattice algorithm, significantly improved scaling is possible. However, in this approach the size of activated events is limited by the processor size while the dynamics is not exact. Here we discuss progress in improving the scaling of serial TAD by combining the use of on-the-fly transition searching with our previously developed localized saddle-point method. We demonstrate improved performance for the cases of Ag/Ag(100) annealing and Cu/Cu(100) growth. Supported by NSF DMR-1410840.
Tunable strength saddle-point contacts impact on quantum rings transmission

NASA Astrophysics Data System (ADS)

González, J. J.; Diago-Cisneros, L.

2016-09-01

A particular subject of investigation is the role of several sadle-point contact (QPC) parameters on the scattering properties of an Aharonov-Bohm-Aharonov-Casher quantum ring (QR) under Rashba-type spin orbit interaction. We discuss the interplay of the conductance with the confinement strengths and height of the QPC, which yields new and tunable harmonic and non-harmonics patterns, while one manipulates these constriction parameters. This phenomenology may be of utility to implement a novel way to modulate spin interference effects in semiconducting QRs, providing an appealing test-platform for spintronics applications.
Search for point sources of high energy neutrinos with final data from AMANDA-II

NASA Astrophysics Data System (ADS)

Abbasi, R.; Ackermann, M.; Adams, J.; Ahlers, M.; Ahrens, J.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Baret, B.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Becka, T.; Becker, J. K.; Becker, K.-H.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Bolmont, J.; Böser, S.; Botner, O.; Braun, J.; Breder, D.; Burgess, T.; Castermans, T.; Chirkin, D.; Christy, B.; Clem, J.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Davour, A.; Day, C. T.; Depaepe, O.; de Clercq, C.; Demirörs, L.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; De Young, T.; Diaz-Velez, J. C.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Edwards, W. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Ganugapati, R.; Gerhardt, L.; Gladstone, L.; Goldschmidt, A.; Goodman, J. A.; Gozzini, R.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gunasingha, R. M.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Hardtke, R.; Hasegawa, Y.; Heise, J.; Helbing, K.; Hellwig, M.; Herquet, P.; Hickford, S.; Hill, G. C.; Hodges, J.; Hoffman, K. D.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hughey, B.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hundertmark, S.; Hussain, S.; Imlay, R. L.; Inaba, M.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kawai, H.; Kelley, J. L.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Klepser, S.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Kuehn, K.; Kuwabara, T.; Labare, M.; Laihem, K.; Landsman, H.; Lauer, R.; Leich, H.; Leier, D.; Lewis, C.; Lucke, A.; Lundberg, J.; Lünemann, J.; Madsen, J.; Maruyama, R.; Mase, K.; Matis, H. S.; McParland, C. P.; Meagher, K.; Meli, A.; Merck, M.; Messarius, T.; Mészáros, P.; Miyamoto, H.; Mohr, A.; Montaruli, T.; Morse, R.; Movit, S. M.; Münich, K.; Nahnhauer, R.; Nam, J. W.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; Ono, M.; Panknin, S.; Patton, S.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Pohl, A. C.; Porrata, R.; Potthoff, N.; Pretz, J.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Razzaque, S.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Robbins, W. J.; Rodriguez, J.; Roth, P.; Rothmaier, F.; Rott, C.; Roucelle, C.; Rutledge, D.; Ryckbosch, D.; Sander, H.-G.; Sarkar, S.; Satalecka, K.; Schlenstedt, S.; Schmidt, T.; Schneider, D.; Schultz, O.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Smith, A. J.; Song, C.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stezelberger, T.; Stokstad, R. G.; Stoufer, M. C.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sulanke, K.-H.; Sullivan, G. W.; Swillens, Q.; Taboada, I.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Tluczykont, M.; Toale, P. A.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; Viscomi, V.; Vogt, C.; Voigt, B.; Walck, C.; Waldenmaier, T.; Walter, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebusch, C. H.; Wiedemann, C.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Xu, X. W.; Yodh, G.; Yoshida, S.

2009-03-01

We present a search for point sources of high energy neutrinos using 3.8 yr of data recorded by AMANDA-II during 2000-2006. After reconstructing muon tracks and applying selection criteria designed to optimally retain neutrino-induced events originating in the northern sky, we arrive at a sample of 6595 candidate events, predominantly from atmospheric neutrinos with primary energy 100 GeV to 8 TeV. Our search of this sample reveals no indications of a neutrino point source. We place the most stringent limits to date on E-2 neutrino fluxes from points in the northern sky, with an average upper limit of E2Φνμ+ντ≤5.2×10-11TeVcm-2s-1 on the sum of νμ and ντ fluxes, assumed equal, over the energy range from 1.9 TeV to 2.5 PeV.
Statistical prescission point model of fission fragment angular distributions

NASA Astrophysics Data System (ADS)

John, Bency; Kataria, S. K.

1998-03-01

In light of recent developments in fission studies such as slow saddle to scission motion and spin equilibration near the scission point, the theory of fission fragment angular distribution is examined and a new statistical prescission point model is developed. The conditional equilibrium of the collective angular bearing modes at the prescission point, which is guided mainly by their relaxation times and population probabilities, is taken into account in the present model. The present model gives a consistent description of the fragment angular and spin distributions for a wide variety of heavy and light ion induced fission reactions.
Search for Point Sources of High Energy Neutrinos with Final Data from AMANDA-II

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

IceCube Collaboration; Klein, Spencer

2009-03-06

We present a search for point sources of high energy neutrinos using 3.8 years of data recorded by AMANDA-II during 2000-2006. After reconstructing muon tracks and applying selection criteria designed to optimally retain neutrino-induced events originating in the Northern Sky, we arrive at a sample of 6595 candidate events, predominantly from atmospheric neutrinos with primary energy 100 GeV to 8 TeV. Our search of this sample reveals no indications of a neutrino point source. We place the most stringent limits to date on E{sup -2} neutrino fluxes from points in the Northern Sky, with an average upper limit of E{supmore » 2}{Phi}{sub {nu}{sub {mu}}+{nu}{sub {tau}}} {le} 5.2 x 10{sup -11} TeV cm{sup -2} s{sup -1} on the sum of {nu}{sub {mu}} and {nu}{sub {tau}} fluxes, assumed equal, over the energy range from 1.9 TeV to 2.5 PeV.« less
Search for point sources of high energy neutrinos with final data from AMANDA-II

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

Abbasi, R.; Andeen, K.; Baker, M.

2009-03-15

We present a search for point sources of high energy neutrinos using 3.8 yr of data recorded by AMANDA-II during 2000-2006. After reconstructing muon tracks and applying selection criteria designed to optimally retain neutrino-induced events originating in the northern sky, we arrive at a sample of 6595 candidate events, predominantly from atmospheric neutrinos with primary energy 100 GeV to 8 TeV. Our search of this sample reveals no indications of a neutrino point source. We place the most stringent limits to date on E{sup -2} neutrino fluxes from points in the northern sky, with an average upper limit of E{supmore » 2}{phi}{sub {nu}{sub {mu}}}{sub +{nu}{sub {tau}}}{<=}5.2x10{sup -11} TeV cm{sup -2} s{sup -1} on the sum of {nu}{sub {mu}} and {nu}{sub {tau}} fluxes, assumed equal, over the energy range from 1.9 TeV to 2.5 PeV.« less

Dynamical importance of van der Waals saddle and excited potential surface in C(1D)+D2 complex-forming reaction

PubMed Central

Shen, Zhitao; Ma, Haitao; Zhang, Chunfang; Fu, Mingkai; Wu, Yanan; Bian, Wensheng; Cao, Jianwei

2017-01-01

Encouraged by recent advances in revealing significant effects of van der Waals wells on reaction dynamics, many people assume that van der Waals wells are inevitable in chemical reactions. Here we find that the weak long-range forces cause van der Waals saddles in the prototypical C(1D)+D2 complex-forming reaction that have very different dynamical effects from van der Waals wells at low collision energies. Accurate quantum dynamics calculations on our highly accurate ab initio potential energy surfaces with van der Waals saddles yield cross-sections in close agreement with crossed-beam experiments, whereas the same calculations on an earlier surface with van der Waals wells produce much smaller cross-sections at low energies. Further trajectory calculations reveal that the van der Waals saddle leads to a torsion then sideways insertion reaction mechanism, whereas the well suppresses reactivity. Quantum diffraction oscillations and sharp resonances are also predicted based on our ground- and excited-state potential energy surfaces. PMID:28094253
Fast grasping of unknown objects using cylinder searching on a single point cloud

NASA Astrophysics Data System (ADS)

Lei, Qujiang; Wisse, Martijn

2017-03-01

Grasping of unknown objects with neither appearance data nor object models given in advance is very important for robots that work in an unfamiliar environment. The goal of this paper is to quickly synthesize an executable grasp for one unknown object by using cylinder searching on a single point cloud. Specifically, a 3D camera is first used to obtain a partial point cloud of the target unknown object. An original method is then employed to do post treatment on the partial point cloud to minimize the uncertainty which may lead to grasp failure. In order to accelerate the grasp searching, surface normal of the target object is then used to constrain the synthetization of the cylinder grasp candidates. Operability analysis is then used to select out all executable grasp candidates followed by force balance optimization to choose the most reliable grasp as the final grasp execution. In order to verify the effectiveness of our algorithm, Simulations on a Universal Robot arm UR5 and an under-actuated Lacquey Fetch gripper are used to examine the performance of this algorithm, and successful results are obtained.
Chiral interface at the finite temperature transition point of QCD

NASA Technical Reports Server (NTRS)

Frei, Z.; Patkos, A.

1990-01-01

The domain wall between coexisting chirally symmetric and broken symmetry regions is studied in a saddle point approximation to the effective three-flavor sigma model. In the chiral limit the surface tension varies in the range ((40 to -50)MeV)(exp 3). The width of the domain wall is estimated to be approximately or equal to 4.5 fm.
Monolithic diffraction-limited 976-nm laser based on saddle-shaped photo darkening-free Yb-doped fiber

NASA Astrophysics Data System (ADS)

Aleshkina, Svetlana S.; Lipatov, Denis S.; Levchenko, Andrei E.; Medvedkov, Oleg I.; Bobkov, Konstantin K.; Bubnov, Mikhail M.; Guryanov, Alexei N.; Likhachev, Mikhail E.

2018-02-01

Monolithic 976 nm laser design based on a newly developed saddle-shaped Yb-doped fiber has been proposed. The fiber has central single-mode part with core diameter of about 12 μm and ultra-thin square-shaped clad with side of about 42x42 μm. At the both ends of the saddle-shaped fiber the core and the clad sizes were adiabatically increased up to 20/(70x70) μm and the fiber could be spliced with standard (80..125 μm clad) passive fibers using commercially available equipment. Single-mode laser at 976 nm based on the developed fiber has been fabricated and photodarkening-free operation with output power of 10.6 W, which is the record high for all-fiber laser schemes, has been demonstrated.
All flavour point-source search with the ANTARES neutrino telescope

NASA Astrophysics Data System (ADS)

Michael, Tino

2017-09-01

ANTARES is the largest neutrino telescope in the Northern Hemisphere. The detector has established excellent pointing resolution for muon neutrinos (0.4 degrees) and a degree-level resolution also for contained shower events (about 2 degrees). Together with its geographical location, the good angular resolution makes ANTARES an excellent tool to test for the presence of cosmic sources in the Southern Hemisphere and in particular the area around the Galactic Centre, where IceCube reports a number of high-energy events. In this contribution, we present a search for cosmic neutrino sources using ANTARES data taken from early 2007 until the end of 2013. Such sources are identified as a cluster of events in the combined track and shower channels. In addition to the all-flavour full-sky and candidate list searches, we focus on a restricted region around the Galactic Centre. Different spectral indices for the neutrino energy spectrum have been investigated as well as possible extended sources.
Symbiotic organisms search algorithm for dynamic economic dispatch with valve-point effects

NASA Astrophysics Data System (ADS)

Sonmez, Yusuf; Kahraman, H. Tolga; Dosoglu, M. Kenan; Guvenc, Ugur; Duman, Serhat

2017-05-01

In this study, symbiotic organisms search (SOS) algorithm is proposed to solve the dynamic economic dispatch with valve-point effects problem, which is one of the most important problems of the modern power system. Some practical constraints like valve-point effects, ramp rate limits and prohibited operating zones have been considered as solutions. Proposed algorithm was tested on five different test cases in 5 units, 10 units and 13 units systems. The obtained results have been compared with other well-known metaheuristic methods reported before. Results show that proposed algorithm has a good convergence and produces better results than other methods.
Risk factors for saddle-related skin lesions on elephants used in the tourism industry in Thailand.

PubMed

Magda, Scarlett; Spohn, Olivia; Angkawanish, Taweepoke; Smith, Dale A; Pearl, David L

2015-05-19

Lesions related to working conditions and improper saddle design are a concern for a variety of working animals including elephants. The objectives of the present study were to determine the prevalence of cutaneous lesions in anatomic regions (i.e., neck, girth, back, tail) in contact with saddle-related equipment among elephants in Thailand working in the tourism industry, and to identify potential risk factors associated with these lesions. Data for this cross-sectional study were collected between May 2007 and July 2007 on 194 elephants from 18 tourism camps across Thailand. There was a high prevalence (64.4 %; 95 % CI 57.3 - 71.2) of active lesions, most often located on the back region. Using multilevel multivariable logistic regression modelling containing a random intercept for camp we identified the following risk factors: increasing elephant age, the use of rice sacks as padding material in contact with the skin, and the provision of a break for the elephants. Working hours had a quadratic relationship with the log odds of an active lesion where the probability of an active lesion initially increased with the number of working hours per day and then declined possibly reflecting a "healthy worker" bias where only animals without lesions continue to be able to work these longer hours. While we recognize that the cross-sectional nature of the study posed some inferential limitations, our results offer several potential intervention points for the prevention of these lesions. Specifically, we recommend the following until longitudinal studies can be conducted: increased monitoring of older elephants and the back region of all elephants, working less than 6 hours per day, and the avoidance of rice sacks as padding material in contact with skin.
On the late-time behavior of Virasoro blocks and a classification of semiclassical saddles

DOE PAGES

Fitzpatrick, A. Liam; Kaplan, Jared

2017-04-12

Recent work has demonstrated that black hole thermodynamics and information loss/restoration in AdS 3/CFT 2 can be derived almost entirely from the behavior of the Virasoro conformal blocks at large central charge, with relatively little dependence on the precise details of the CFT spectrum or OPE coefficients. Here, we elaborate on the non-perturbative behavior of Virasoro blocks by classifying all ‘saddles’ that can contribute for arbitrary values of external and internal operator dimensions in the semiclassical large central charge limit. The leading saddles, which determine the naive semiclassical behavior of the Virasoro blocks, all decay exponentially at late times, andmore » at a rate that is independent of internal operator dimensions. Consequently, the semiclassical contribution of a finite number of high-energy states cannot resolve a well-known version of the information loss problem in AdS 3. Furthermore, we identify two infinite classes of sub-leading saddles, and one of these classes does not decay at late times.« less
Monitoring populations of saddled prominent (Lepidoptera: Notodontidae) with pheromone-baited traps.

PubMed

Spear-O'Mara, Jennifer; Allen, Douglas C

2007-04-01

Field trials with three types of pheromone traps were performed in eight northern hardwood stands in northern New York state to develop a population-monitoring tool for the saddled prominent, Heterocampa guttivitta (Walker) (Lepidoptera: Notodontidae). Lure specificity and the relationship between pheromone trap catch and subsequent egg density were examined. A study of moth emergence in relation to temperature was designed to determine whether moth activity throughout the flight season can be predicted using a growing degree-day (DD) model. Pherocon 1C wing traps were significantly more effective than the green Unitrap bucket style. Catch was not affected by position when traps were > or =20 m from an opening (road), and lures were specific to saddled prominent. Lure specificity was examined using green Multipher bucket traps, which effectively attracted and held moths. In the first year of the study, number of viable eggs per 10 leaf clusters was significantly correlated (r2 = 0.59) with average moth catch/trap in pheromone-baited Pherocon traps. When differences in stand density (basal area) and relative abundance of sugar maple (percentage of total stems per hectare), the principle host, were accounted for, the multiple regression model also was significant and r2 = 0. 83. Neither model, however, was significant the second year. Using a base temperature of 5.5 degrees C and on-site temperature data, the peak of moth flight occurred at 316 +/- 8 DD and end of flight occurred at 533 +/- 9 DD.
High pressure hydrogen stabilised by quantum nuclear motion

NASA Astrophysics Data System (ADS)

Needs, Richard; Monserrat, Bartomeu; Pickard, Chris

Hydrogen under extreme pressures is of fundamental interest, as it might exhibit exotic physical phenomena, and of practical interest, as it is a major component of many astrophysical objects. Structure searches have been successful at identifying promising candidates for the known phases of high pressure hydrogen. However, these searches have so far been restricted to the location of minima of the potential energy landscape. In this talk, we will describe a new structure searching method, ``saddle-point ab initio random structure searching'' (sp-AIRSS), that allows us to identify structures associated with saddle points of the potential energy landscape. Using sp-AIRSS, we find two new high-pressure hydrogen structures that exhibit a harmonic dynamical instability, but quantum and thermal anharmonic motion render them dynamically stable. These structures are formed by mixed layers of strongly and softly bound hydrogen molecules, and become thermodynamically competitive at the highest pressures reached in experiment. The experimental implications of these new structures will also be discussed. BM is supported by Robinson College, Cambridge, and the Cambridge Philosophical Society. RJN and CJP are supported by the Engineering and Physical Sciences Research Council (EPSRC) of the UK.
LiveWire interactive boundary extraction algorithm based on Haar wavelet transform and control point set direction search

NASA Astrophysics Data System (ADS)

Cheng, Jun; Zhang, Jun; Tian, Jinwen

2015-12-01

Based on deep analysis of the LiveWire interactive boundary extraction algorithm, a new algorithm focusing on improving the speed of LiveWire algorithm is proposed in this paper. Firstly, the Haar wavelet transform is carried on the input image, and the boundary is extracted on the low resolution image obtained by the wavelet transform of the input image. Secondly, calculating LiveWire shortest path is based on the control point set direction search by utilizing the spatial relationship between the two control points users provide in real time. Thirdly, the search order of the adjacent points of the starting node is set in advance. An ordinary queue instead of a priority queue is taken as the storage pool of the points when optimizing their shortest path value, thus reducing the complexity of the algorithm from O[n2] to O[n]. Finally, A region iterative backward projection method based on neighborhood pixel polling has been used to convert dual-pixel boundary of the reconstructed image to single-pixel boundary after Haar wavelet inverse transform. The algorithm proposed in this paper combines the advantage of the Haar wavelet transform and the advantage of the optimal path searching method based on control point set direction search. The former has fast speed of image decomposition and reconstruction and is more consistent with the texture features of the image and the latter can reduce the time complexity of the original algorithm. So that the algorithm can improve the speed in interactive boundary extraction as well as reflect the boundary information of the image more comprehensively. All methods mentioned above have a big role in improving the execution efficiency and the robustness of the algorithm.
Saddle Slow Manifolds and Canard Orbits in [Formula: see text] and Application to the Full Hodgkin-Huxley Model.

PubMed

Hasan, Cris R; Krauskopf, Bernd; Osinga, Hinke M

2018-04-19

Many physiological phenomena have the property that some variables evolve much faster than others. For example, neuron models typically involve observable differences in time scales. The Hodgkin-Huxley model is well known for explaining the ionic mechanism that generates the action potential in the squid giant axon. Rubin and Wechselberger (Biol. Cybern. 97:5-32, 2007) nondimensionalized this model and obtained a singularly perturbed system with two fast, two slow variables, and an explicit time-scale ratio ε. The dynamics of this system are complex and feature periodic orbits with a series of action potentials separated by small-amplitude oscillations (SAOs); also referred to as mixed-mode oscillations (MMOs). The slow dynamics of this system are organized by two-dimensional locally invariant manifolds called slow manifolds which can be either attracting or of saddle type.In this paper, we introduce a general approach for computing two-dimensional saddle slow manifolds and their stable and unstable fast manifolds. We also develop a technique for detecting and continuing associated canard orbits, which arise from the interaction between attracting and saddle slow manifolds, and provide a mechanism for the organization of SAOs in [Formula: see text]. We first test our approach with an extended four-dimensional normal form of a folded node. Our results demonstrate that our computations give reliable approximations of slow manifolds and canard orbits of this model. Our computational approach is then utilized to investigate the role of saddle slow manifolds and associated canard orbits of the full Hodgkin-Huxley model in organizing MMOs and determining the firing rates of action potentials. For ε sufficiently large, canard orbits are arranged in pairs of twin canard orbits with the same number of SAOs. We illustrate how twin canard orbits partition the attracting slow manifold into a number of ribbons that play the role of sectors of rotations. The upshot is that we
Flood-inundation maps for the Saddle River from Rochelle Park to Lodi, New Jersey, 2012

USGS Publications Warehouse

Hoppe, Heidi L.; Watson, Kara M.

2012-01-01

Digital flood-inundation maps for a 2.75-mile reach of the Saddle River from 0.2 mile upstream from the Interstate 80 bridge in Rochelle Park to 1.5 miles downstream from the U.S. Route 46 bridge in Lodi, New Jersey, were created by the U.S. Geological Survey (USGS) in cooperation with the New Jersey Department of Environmental Protection (NJDEP). The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage at Saddle River at Lodi, New Jersey (station 01391500). Current conditions for estimating near real-time areas of inundation using USGS streamgage information may be obtained on the Internet at http://waterdata.usgs.gov/nwis/uv?site_no=01391500. The National Weather Service (NWS) forecasts flood hydrographs at many places that are often collocated with USGS streamgages. NWS-forecasted peak-stage information may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. In this study, flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated using the most current stage-discharge relations at the Saddle River at Lodi, New Jersey streamgage and documented high-water marks from recent floods. The hydraulic model was then used to determine 11 water-surface profiles for flood stages at the Saddle River streamgage at 1-ft intervals referenced to the streamgage datum, North American Vertical Datum of 1988 (NAVD 88), and ranging from bankfull, 0.5 ft below NWS Action Stage, to the extent of the stage-discharge rating, which is approximately 1 ft higher than the highest recorded water level at the streamgage. Action Stage is the stage which when reached by a rising stream the NWS or a partner needs to take some type of mitigation action in
A Targeted Search for Point Sources of EeV Photons with the Pierre Auger Observatory

NASA Astrophysics Data System (ADS)

Aab, A.; Abreu, P.; Aglietta, M.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Barreira Luz, R. J.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Chavez, A. G.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; D'Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; Debatin, J.; Deligny, O.; Di Giulio, C.; Di Matteo, A.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D'Olivo, J. C.; Dorosti, Q.; dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fick, B.; Figueira, J. M.; Filipčič, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; Gaior, R.; García, B.; Garcia-Pinto, D.; Gaté, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Głas, D.; Glaser, C.; Golup, G.; Gómez Berisso, M.; Gómez Vitale, P. F.; González, N.; Gorgi, A.; Gorham, P.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Johnsen, J. A.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kemp, J.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A.; LaHurd, D.; Lauscher, M.; Legumina, R.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; López, R.; López Casado, A.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Mariş, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martínez Bravo, O.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Mockler, D.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafá, M.; Müller, A. L.; Müller, G.; Muller, M. A.; Müller, S.; Mussa, R.; Naranjo, I.; Nellen, L.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, H.; Núñez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Pȩkala, J.; Pelayo, R.; Peña-Rodriguez, J.; Pereira, L. A. S.; Perlín, M.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollan, R.; Rautenberg, J.; Ravignani, D.; Revenu, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rogozin, D.; Roncoroni, M. J.; Roth, M.; Roulet, E.; Rovero, A. C.; Ruehl, P.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarmento, R.; Sarmiento, C. A.; Sato, R.; Schauer, M.; Scherini, V.; Schieler, H.; Schimp, M.; Schmidt, D.; Scholten, O.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Stanca, D.; Stanič, S.; Stasielak, J.; Stassi, P.; Strafella, F.; Suarez, F.; Suarez Durán, M.; Sudholz, T.; Suomijärvi, T.; Supanitsky, A. D.; Swain, J.; Szadkowski, Z.; Taboada, A.; Taborda, O. A.; Tapia, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tomé, B.; Torralba Elipe, G.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Vergara Quispe, I. D.; Verzi, V.; Vicha, J.; Villaseñor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczyński, H.; Winchen, T.; Wirtz, M.; Wittkowski, D.; Wundheiler, B.; Yang, L.; Yelos, D.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zuccarello, F.

2017-03-01

Simultaneous measurements of air showers with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for EeV photon point sources. Several Galactic and extragalactic candidate objects are grouped in classes to reduce the statistical penalty of many trials from that of a blind search and are analyzed for a significant excess above the background expectation. The presented search does not find any evidence for photon emission at candidate sources, and combined p-values for every class are reported. Particle and energy flux upper limits are given for selected candidate sources. These limits significantly constrain predictions of EeV proton emission models from non-transient Galactic and nearby extragalactic sources, as illustrated for the particular case of the Galactic center region.
A Targeted Search for Point Sources of EeV Photons with the Pierre Auger Observatory

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

Aab, A.; Abreu, P.; Aglietta, M.

Simultaneous measurements of air showers with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for EeV photon point sources. Several Galactic and extragalactic candidate objects are grouped in classes to reduce the statistical penalty of many trials from that of a blind search and are analyzed for a significant excess above the background expectation. The presented search does not find any evidence for photon emission at candidate sources, and combined p-values for every class are reported. Particle and energy flux upper limits are given for selected candidate sources. Lastly, these limits significantly constrain predictionsmore » of EeV proton emission models from non-transient Galactic and nearby extragalactic sources, as illustrated for the particular case of the Galactic center region.« less
A Targeted Search for Point Sources of EeV Photons with the Pierre Auger Observatory

DOE PAGES

Aab, A.; Abreu, P.; Aglietta, M.; ...

2017-03-09

Simultaneous measurements of air showers with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for EeV photon point sources. Several Galactic and extragalactic candidate objects are grouped in classes to reduce the statistical penalty of many trials from that of a blind search and are analyzed for a significant excess above the background expectation. The presented search does not find any evidence for photon emission at candidate sources, and combined p-values for every class are reported. Particle and energy flux upper limits are given for selected candidate sources. Lastly, these limits significantly constrain predictionsmore » of EeV proton emission models from non-transient Galactic and nearby extragalactic sources, as illustrated for the particular case of the Galactic center region.« less
A Targeted Search for Point Sources of EeV Photons with the Pierre Auger Observatory

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

Aab, A.; Abreu, P.; Aglietta, M.

Simultaneous measurements of air showers with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for EeV photon point sources. Several Galactic and extragalactic candidate objects are grouped in classes to reduce the statistical penalty of many trials from that of a blind search and are analyzed for a significant excess above the background expectation. The presented search does not find any evidence for photon emission at candidate sources, and combined p -values for every class are reported. Particle and energy flux upper limits are given for selected candidate sources. These limits significantly constrain predictionsmore » of EeV proton emission models from non-transient Galactic and nearby extragalactic sources, as illustrated for the particular case of the Galactic center region.« less
Segmented saddle-shaped passive stabilization conductors for toroidal plasmas

DOEpatents

Leuer, James A.

1990-05-01

A large toroidal vacuum chamber for plasma generation and confinement is lined with a toroidal blanket for shielding using modules segmented in the toroidal direction. To provide passive stabilization in the same manner as a conductive vacuum chamber wall, saddle-shaped conductor loops are provided on blanket modules centered on a midplane of the toroidal chamber with horizontal conductive bars above and below the midplane, and vertical conductive legs on opposite sides of each module to provide return current paths between the upper and lower horizontal conductive bars. The close proximity of the vertical legs provided on adjacent modules without making physical contact cancel the electromagnetic field of adjacent vertical legs. The conductive bars spaced equally above and below the midplane simulate toroidal conductive loops or hoops that are continuous, for vertical stabilization of the plasma even though they are actually segmented.
Hamiltonian flow over saddles for exploring molecular phase space structures

NASA Astrophysics Data System (ADS)

Farantos, Stavros C.

2018-03-01

Despite using potential energy surfaces, multivariable functions on molecular configuration space, to comprehend chemical dynamics for decades, the real happenings in molecules occur in phase space, in which the states of a classical dynamical system are completely determined by the coordinates and their conjugate momenta. Theoretical and numerical results are presented, employing alanine dipeptide as a model system, to support the view that geometrical structures in phase space dictate the dynamics of molecules, the fingerprints of which are traced by following the Hamiltonian flow above saddles. By properly selecting initial conditions in alanine dipeptide, we have found internally free rotor trajectories the existence of which can only be justified in a phase space perspective. This article is part of the theme issue `Modern theoretical chemistry'.
Singular perturbations and vanishing passage through a turning point

NASA Astrophysics Data System (ADS)

De Maesschalck, P.; Dumortier, F.

The paper deals with planar slow-fast cycles containing a unique generic turning point. We address the question on how to study canard cycles when the slow dynamics can be singular at the turning point. We more precisely accept a generic saddle-node bifurcation to pass through the turning point. It reveals that in this case the slow divergence integral is no longer the good tool to use, but its derivative with respect to the layer variable still is. We provide general results as well as a number of applications. We show how to treat the open problems presented in Artés et al. (2009) [1] and Dumortier and Rousseau (2009) [13], dealing respectively with the graphics DI2a and DF1a from Dumortier et al. (1994) [14].

An algorithm to locate optimal bond breaking points on a potential energy surface for applications in mechanochemistry and catalysis.

PubMed

Bofill, Josep Maria; Ribas-Ariño, Jordi; García, Sergio Pablo; Quapp, Wolfgang

2017-10-21

The reaction path of a mechanically induced chemical transformation changes under stress. It is well established that the force-induced structural changes of minima and saddle points, i.e., the movement of the stationary points on the original or stress-free potential energy surface, can be described by a Newton Trajectory (NT). Given a reactive molecular system, a well-fitted pulling direction, and a sufficiently large value of the force, the minimum configuration of the reactant and the saddle point configuration of a transition state collapse at a point on the corresponding NT trajectory. This point is called barrier breakdown point or bond breaking point (BBP). The Hessian matrix at the BBP has a zero eigenvector which coincides with the gradient. It indicates which force (both in magnitude and direction) should be applied to the system to induce the reaction in a barrierless process. Within the manifold of BBPs, there exist optimal BBPs which indicate what is the optimal pulling direction and what is the minimal magnitude of the force to be applied for a given mechanochemical transformation. Since these special points are very important in the context of mechanochemistry and catalysis, it is crucial to develop efficient algorithms for their location. Here, we propose a Gauss-Newton algorithm that is based on the minimization of a positively defined function (the so-called σ-function). The behavior and efficiency of the new algorithm are shown for 2D test functions and for a real chemical example.
Segmented saddle-shaped passive stabilization conductors for toroidal plasmas

DOEpatents

Leuer, J.A.

1990-05-01

A large toroidal vacuum chamber for plasma generation and confinement is lined with a toroidal blanket for shielding using modules segmented in the toroidal direction. To provide passive stabilization in the same manner as a conductive vacuum chamber wall, saddle-shaped conductor loops are provided on blanket modules centered on a midplane of the toroidal chamber with horizontal conductive bars above and below the midplane, and vertical conductive legs on opposite sides of each module to provide return current paths between the upper and lower horizontal conductive bars. The close proximity of the vertical legs provided on adjacent modules without making physical contact cancel the electromagnetic field of adjacent vertical legs. The conductive bars spaced equally above and below the midplane simulate toroidal conductive loops or hoops that are continuous, for vertical stabilization of the plasma even though they are actually segmented. 5 figs.
A Blind Hydrothermal System in an Ocean Island Environment: Humu'ula Saddle, Hawaii Island

NASA Astrophysics Data System (ADS)

Thomas, D. M.; Wallin, E.; Lautze, N. C.; Lienert, B. R.; Pierce, H. A.

2014-12-01

A recently drilled groundwater investigation borehole, drilled to a depth of 1760 m in the Humu'ula Saddle of Hawaii Island, encountered an unexpectedly high temperature gradient of more than 160 ̊C/km. Although prior MT surveys across the region identified conductive formations of modest extent in the region, there were few surface manifestations of geologic structures likely to host a geothermal system and no evidence of an active, extensive hydrothermal system. Cores recovered from the borehole showed the presence of intrusive formations and moderate hydrothermal alteration at depth with progressive infilling of fractures and vesicles with depth and temperature. Independent modeling of gravity data (Flinders et al., 2013) suggests the presence of a broad intrusive complex within the region that is consistent with the borehole's confirmation of a high-elevation (~1400 m amsl) regional water table. A subsequent MT survey covering much of the western Saddle region has confirmed the presence of highly conductive conditions, consistent with thermal activity, to depths of 4 km and greater. Light stable isotope data for the borehole fluids indicate that the regional water table is derived from recharge from the upper elevations of Mauna Kea; major element chemistry indicates that formation temperatures exceed 200 ̊C. A conceptual model of the hydrothermal system, along with isotopic and fluid chemistry of the thermal fluids will be presented.
THE FIRST COMBINED SEARCH FOR NEUTRINO POINT-SOURCES IN THE SOUTHERN HEMISPHERE WITH THE ANTARES AND ICECUBE NEUTRINO TELESCOPES

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

Adrián-Martínez, S.; Ardid, M.; Albert, A.

2016-05-20

We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors, which differ in size and location, forms a window in the southern sky where the sensitivity to point sources improves by up to a factor of 2 compared with individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the southern sky and from a preselected list of candidate objects. Nomore » significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for E {sup −2.5} and E {sup −2} power-law spectra with different energy cut-offs.« less
Provenance of Cretaceous-Pliocene Clastic Sediments in the Tachira Saddle, Western Venezuela, and Implications for Sediment Dispersal Patterns in the Northern Andes

NASA Astrophysics Data System (ADS)

Gomez, Ali Ricardo

Northwestern South America is highly deformed due to the transpressive plate boundary associated with complex interactions between the Caribbean plate, the South American plate, the Nazca plate and the Panama arc. Previous studies suggest that the Cenozoic uplift of the Merida Andes and Eastern Cordillera of Colombia affected sediment dispersal patterns in the region, shifting from a Paleocene foreland basin configuration to the modern isolated basins. Well-exposed Cretaceous to Pliocene strata in the Tachira Saddle provides a unique opportunity to test proposed sediment dispersal patterns in the region. U-Pb detrital zircon geochronology and supplementary XRD heavy mineral data are used together to document the provenance of the Tachira Saddle sediments and refine the sediment dispersal patterns in the region. Results from the U-Pb detrital zircon geochronology show that there are six age groups recorded in these samples. Two groups are related to the Precambrian Guyana shield terranes and Putumayo basement in the Eastern Cordillera, and four groups are related to different magmatic episodes occurring during the Andean orogenic process. The transition between the Cretaceous passive margin and the Paleocene foreland basin and the initial uplift of the Eastern Cordillera and the uplift of the Merida Andes by the Early Miocene were also recorded in the Tachira saddle detrital zircon signature.
FloPSy - Search-Based Floating Point Constraint Solving for Symbolic Execution

NASA Astrophysics Data System (ADS)

Lakhotia, Kiran; Tillmann, Nikolai; Harman, Mark; de Halleux, Jonathan

Recently there has been an upsurge of interest in both, Search-Based Software Testing (SBST), and Dynamic Symbolic Execution (DSE). Each of these two approaches has complementary strengths and weaknesses, making it a natural choice to explore the degree to which the strengths of one can be exploited to offset the weakness of the other. This paper introduces an augmented version of DSE that uses a SBST-based approach to handling floating point computations, which are known to be problematic for vanilla DSE. The approach has been implemented as a plug in for the Microsoft Pex DSE testing tool. The paper presents results from both, standard evaluation benchmarks, and two open source programs.
Application of the nudged elastic band method to the point-to-point radio wave ray tracing in IRI modeled ionosphere

NASA Astrophysics Data System (ADS)

Nosikov, I. A.; Klimenko, M. V.; Bessarab, P. F.; Zhbankov, G. A.

2017-07-01

Point-to-point ray tracing is an important problem in many fields of science. While direct variational methods where some trajectory is transformed to an optimal one are routinely used in calculations of pathways of seismic waves, chemical reactions, diffusion processes, etc., this approach is not widely known in ionospheric point-to-point ray tracing. We apply the Nudged Elastic Band (NEB) method to a radio wave propagation problem. In the NEB method, a chain of points which gives a discrete representation of the radio wave ray is adjusted iteratively to an optimal configuration satisfying the Fermat's principle, while the endpoints of the trajectory are kept fixed according to the boundary conditions. Transverse displacements define the radio ray trajectory, while springs between the points control their distribution along the ray. The method is applied to a study of point-to-point ionospheric ray tracing, where the propagation medium is obtained with the International Reference Ionosphere model taking into account traveling ionospheric disturbances. A 2-dimensional representation of the optical path functional is developed and used to gain insight into the fundamental difference between high and low rays. We conclude that high and low rays are minima and saddle points of the optical path functional, respectively.
Saddle antenna radio frequency ion sources

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

Dudnikov, V., E-mail: vadim@muonsinc.com; Johnson, R.; Murray, S.

Existing RF ion sources for accelerators have specific efficiencies for H{sup +} and H{sup −} ion generation ∼3–5 mA/cm{sup 2} kW, where about 50 kW of RF power is typically needed for 50 mA beam current production. The Saddle Antenna (SA) surface plasma source (SPS) described here was developed to improve H{sup −} ion production efficiency, reliability, and availability. In SA RF ion source, the efficiency of positive ion generation in the plasma has been improved to 200 mA/cm{sup 2} kW. After cesiation, the current of negative ions to the collector was increased from 1 mA to 10 mA withmore » RF power ∼1.5 kW in the plasma (6 mm diameter emission aperture) and up to 30 mA with ∼4 kW RF. Continuous wave (CW) operation of the SA SPS has been tested on the test stand. The general design of the CW SA SPS is based on the pulsed version. Some modifications were made to improve the cooling and cesiation stability. CW operation with negative ion extraction was tested with RF power up to ∼1.2 kW in the plasma with production up to Ic = 7 mA. A stable long time generation of H{sup −} beam without degradation was demonstrated in RF discharge with AlN discharge chamber.« less
Five years of searches for point sources of astrophysical neutrinos with the AMANDA-II neutrino telescope

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

Achterberg, A.; Duvoort, M. R.; Heise, J.

2007-05-15

We report the results of a five-year survey of the northern sky to search for point sources of high energy neutrinos. The search was performed on the data collected with the AMANDA-II neutrino telescope in the years 2000 to 2004, with a live time of 1001 days. The sample of selected events consists of 4282 upward going muon tracks with high reconstruction quality and an energy larger than about 100 GeV. We found no indication of point sources of neutrinos and set 90% confidence level flux upper limits for an all-sky search and also for a catalog of 32 selectedmore » sources. For the all-sky search, our average (over declination and right ascension) experimentally observed upper limit {phi}{sup 0}=((E/1 TeV)){sup {gamma}}{center_dot}(d{phi}/dE) to a point source flux of muon and tau neutrino (detected as muons arising from taus) is {phi}{sub {nu}{sub {mu}}+{nu}{sub {mu}}{sup 0}}+{phi}{sub {nu}{sub {tau}}+{nu}{sub {tau}}}{sup 0}=11.1x 10{sup -11} TeV{sup -1} cm{sup -2} s{sup -1}, in the energy range between 1.6 TeV and 2.5 PeV for a flavor ratio {phi}{sub {nu}{sub {mu}}+{nu}{sub {mu}}{sup 0}}/{phi}{sub {nu}{sub {tau}}+{nu}{sub {tau}}}{sup 0}=1 and assuming a spectral index {gamma}=2. It should be noticed that this is the first time we set upper limits to the flux of muon and tau neutrinos. In previous papers we provided muon neutrino upper limits only neglecting the sensitivity to a signal from tau neutrinos, which improves the limits by 10% to 16%. The value of the average upper limit presented in this work corresponds to twice the limit on the muon neutrino flux {phi}{sub {nu}{sub {mu}}+{nu}{sub {mu}}}{sup 0}=5.5x10{sup -11} TeV{sup -1} cm{sup -2} s{sup -1}. A stacking analysis for preselected active galactic nuclei and a search based on the angular separation of the events were also performed. We report the most stringent flux upper limits to date, including the results of a detailed assessment of systematic uncertainties.« less
Dynamics of Two Point Vortices in an External Compressible Shear Flow

NASA Astrophysics Data System (ADS)

Vetchanin, Evgeny V.; Mamaev, Ivan S.

2017-12-01

This paper is concerned with a system of equations that describes the motion of two point vortices in a flow possessing constant uniform vorticity and perturbed by an acoustic wave. The system is shown to have both regular and chaotic regimes of motion. In addition, simple and chaotic attractors are found in the system. Attention is given to bifurcations of fixed points of a Poincaré map which lead to the appearance of these regimes. It is shown that, in the case where the total vortex strength changes, the "reversible pitch-fork" bifurcation is a typical scenario of emergence of asymptotically stable fixed and periodic points. As a result of this bifurcation, a saddle point, a stable and an unstable point of the same period emerge from an elliptic point of some period. By constructing and analyzing charts of dynamical regimes and bifurcation diagrams we show that a cascade of period-doubling bifurcations is a typical scenario of transition to chaos in the system under consideration.
An efficient interior-point algorithm with new non-monotone line search filter method for nonlinear constrained programming

NASA Astrophysics Data System (ADS)

Wang, Liwei; Liu, Xinggao; Zhang, Zeyin

2017-02-01

An efficient primal-dual interior-point algorithm using a new non-monotone line search filter method is presented for nonlinear constrained programming, which is widely applied in engineering optimization. The new non-monotone line search technique is introduced to lead to relaxed step acceptance conditions and improved convergence performance. It can also avoid the choice of the upper bound on the memory, which brings obvious disadvantages to traditional techniques. Under mild assumptions, the global convergence of the new non-monotone line search filter method is analysed, and fast local convergence is ensured by second order corrections. The proposed algorithm is applied to the classical alkylation process optimization problem and the results illustrate its effectiveness. Some comprehensive comparisons to existing methods are also presented.
Saddle Pulmonary Embolism with Paradoxical Coronary Artery Embolism through a Patent Foramen Ovale.

PubMed

Achesinski, Amber L; Gunther, Wendy M; Pearman, Catherine B

2017-05-01

A 35-year-old male patient was found in cardiac arrest in his vehicle, with no apparent injuries after a minor motor vehicle collision. The decedent was found to have a saddle pulmonary embolus with a thromboembolus impacted across a patent foramen ovale and a paradoxical embolism in the circumflex coronary artery, as well as significant clotting in the deep veins of both lower extremities. There were no risk factors in his history to explain the deep venous thrombosis; family history suggested the possibility of an unrecognized clotting disorder. © 2017 American Academy of Forensic Sciences.
The 8.2 ka cooling event caused by Laurentide ice saddle collapse

NASA Astrophysics Data System (ADS)

Matero, I. S. O.; Gregoire, L. J.; Ivanovic, R. F.; Tindall, J. C.; Haywood, A. M.

2017-09-01

The 8.2 ka event was a period of abrupt cooling of 1-3 °C across large parts of the Northern Hemisphere, which lasted for about 160 yr. The original hypothesis for the cause of this event has been the outburst of the proglacial Lakes Agassiz and Ojibway. These drained into the Labrador Sea in ∼0.5-5 yr and slowed the Atlantic Meridional Overturning Circulation, thus cooling the North Atlantic region. However, climate models have not been able to reproduce the duration and magnitude of the cooling with this forcing without including additional centennial-length freshwater forcings, such as rerouting of continental runoff and ice sheet melt in combination with the lake release. Here, we show that instead of being caused by the lake outburst, the event could have been caused by accelerated melt from the collapsing ice saddle that linked domes over Hudson Bay in North America. We forced a General Circulation Model with time varying meltwater pulses (100-300 yr) that match observed sea level change, designed to represent the Hudson Bay ice saddle collapse. A 100 yr long pulse with a peak of 0.6 Sv produces a cooling in central Greenland that matches the 160 yr duration and 3 °C amplitude of the event recorded in ice cores. The simulation also reproduces the cooling pattern, amplitude and duration recorded in European Lake and North Atlantic sediment records. Such abrupt acceleration in ice melt would have been caused by surface melt feedbacks and marine ice sheet instability. These new realistic forcing scenarios provide a means to reconcile longstanding mismatches between proxy data and models, allowing for a better understanding of both the sensitivity of the climate models and processes and feedbacks in motion during the disintegration of continental ice sheets.
Search for extraterrestrial point sources of high energy neutrinos with AMANDA-II using data collected in 2000-2002

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

Ackermann, M.; Bernardini, E.; Boersma, D.J.

2005-04-01

The results of a search for point sources of high energy neutrinos in the northern hemisphere using data collected by AMANDA-II in the years 2000, 2001, and 2002 are presented. In particular, a comparison with the single-year result previously published shows that the sensitivity was improved by a factor of 2.2. The muon neutrino flux upper limits on selected candidate sources, corresponding to an E{sub {nu}}{sup -2} neutrino energy spectrum, are included. Sky grids were used to search for possible excesses above the background of cosmic ray induced atmospheric neutrinos. This search reveals no statistically significant excess for the threemore » years considered.« less
Generalized Gaussian wave packet dynamics: Integrable and chaotic systems.

PubMed

Pal, Harinder; Vyas, Manan; Tomsovic, Steven

2016-01-01

The ultimate semiclassical wave packet propagation technique is a complex, time-dependent Wentzel-Kramers-Brillouin method known as generalized Gaussian wave packet dynamics (GGWPD). It requires overcoming many technical difficulties in order to be carried out fully in practice. In its place roughly twenty years ago, linearized wave packet dynamics was generalized to methods that include sets of off-center, real trajectories for both classically integrable and chaotic dynamical systems that completely capture the dynamical transport. The connections between those methods and GGWPD are developed in a way that enables a far more practical implementation of GGWPD. The generally complex saddle-point trajectories at its foundation are found using a multidimensional Newton-Raphson root search method that begins with the set of off-center, real trajectories. This is possible because there is a one-to-one correspondence. The neighboring trajectories associated with each off-center, real trajectory form a path that crosses a unique saddle; there are exceptions that are straightforward to identify. The method is applied to the kicked rotor to demonstrate the accuracy improvement as a function of ℏ that comes with using the saddle-point trajectories.
Novel spin transition between S = 5/2 and S = 3/2 in highly saddled iron(III) porphyrin complexes at extremely low temperatures.

PubMed

Ohgo, Yoshiki; Chiba, Yuya; Hashizume, Daisuke; Uekusa, Hidehiro; Ozeki, Tomoji; Nakamura, Mikio

2006-05-14

A novel spin transition between S = 5/2 and S = 3/2 has been observed for the first time in five-coordinate, highly saddled iron(III) porphyrinates by EPR and SQUID measurements at extremely low temperatures.
Search for neutrino point sources with ANTARES 2007-2012 data

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

Zornoza, J. D.

2014-11-18

Neutrinos are unique probes to study the high energy Universe, since they are neutral, only interact weakly and are stable. Furthermore, they can provide key information about several fundamental questions in Physics like the origin of cosmic rays and the nature of dark matter. The ANTARES neutrino telescope, installed in the Mediterranean Sea, has been taking data since 2007. In this paper we review the results concerning the search for point sources of cosmic neutrinos, using data of 2007–2012. Two main strategies have been followed: to look towards the direction of sources candidate to emmit neutrinos and to make anmore » all-sky scan. Although no significant cluster has been found above the background, flux limits have been set at the level of E{sup 2}φν{sup 90CL}∼1–2×10{sup −8} GeV cm{sup −}2s{sup −1}.« less
Time-integrated Searches for Point-like Sources of Neutrinos with the 40-string IceCube Detector

NASA Astrophysics Data System (ADS)

Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brown, A. M.; Buitink, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; De Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; DeYoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feusels, T.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kemming, N.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lehmann, R.; Lünemann, J.; Madsen, J.; Majumdar, P.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Matusik, M.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Ono, M.; Panknin, S.; Paul, L.; Pérez de los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schlenstedt, S.; Schmidt, T.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Singh, K.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; Van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Voigt, B.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; IceCube Collaboration

2011-05-01

We present the results of time-integrated searches for astrophysical neutrino sources in both the northern and southern skies. Data were collected using the partially completed IceCube detector in the 40-string configuration recorded between 2008 April 5 and 2009 May 20, totaling 375.5 days livetime. An unbinned maximum likelihood ratio method is used to search for astrophysical signals. The data sample contains 36,900 events: 14,121 from the northern sky, mostly muons induced by atmospheric neutrinos, and 22,779 from the southern sky, mostly high-energy atmospheric muons. The analysis includes searches for individual point sources and stacked searches for sources in a common class, sometimes including a spatial extent. While this analysis is sensitive to TeV-PeV energy neutrinos in the northern sky, it is primarily sensitive to neutrinos with energy greater than about 1 PeV in the southern sky. No evidence for a signal is found in any of the searches. Limits are set for neutrino fluxes from astrophysical sources over the entire sky and compared to predictions. The sensitivity is at least a factor of two better than previous searches (depending on declination), with 90% confidence level muon neutrino flux upper limits being between E 2 dΦ/dE ~ 2-200 × 10-12 TeV cm-2 s-1 in the northern sky and between 3-700 × 10-12 TeV cm-2 s-1 in the southern sky. The stacked source searches provide the best limits to specific source classes. The full IceCube detector is expected to improve the sensitivity to dΦ/dEvpropE -2 sources by another factor of two in the first year of operation.
A Search for Point Sources of EeV Neutrons

NASA Astrophysics Data System (ADS)

Pierre Auger Collaboration; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antiči'c, T.; Aramo, C.; Arganda, E.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellétoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Buroker, L.; Burton, R. E.; Caballero-Mora, K. S.; Caccianiga, B.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chirinos Diaz, J.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; del Río, M.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giller, M.; Gitto, J.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gouffon, P.; Grashorn, E.; Grebe, S.; Griffith, N.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Hollon, N.; Holmes, V. C.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jansen, S.; Jarne, C.; Jiraskova, S.; Josebachuili, M.; Kadija, K.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D.-H.; Kotera, K.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; LaHurd, D.; Latronico, L.; Lauer, R.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, J.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mazur, P. O.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Mertsch, P.; Meurer, C.; Meyhandan, R.; Mi'canovi'c, S.; Micheletti, M. I.; Minaya, I. A.; Miramonti, L.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Olinto, A.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Peķala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Ponce, V. H.; Pontz, M.; Porcelli, A.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez, G.; Rodriguez Cabo, I.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovánek, P.; Schröder, F.; Schulte, S.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Silva Lopez, H. H.; Sima, O.; 'Smiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanic, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Taşcău, O.; Tcaciuc, R.; Thao, N. T.; Thomas, D.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wommer, M.; Wundheiler, B.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano Garcia, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.

2012-12-01

A thorough search of the sky exposed at the Pierre Auger Cosmic Ray Observatory reveals no statistically significant excess of events in any small solid angle that would be indicative of a flux of neutral particles from a discrete source. The search covers from -90° to +15° in declination using four different energy ranges above 1 EeV (1018 eV). The method used in this search is more sensitive to neutrons than to photons. The upper limit on a neutron flux is derived for a dense grid of directions for each of the four energy ranges. These results constrain scenarios for the production of ultrahigh energy cosmic rays in the Galaxy.
AmeriFlux US-CZ2 Sierra Critical Zone, Sierra Transect, Ponderosa Pine Forest, Soaproot Saddle

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

Goulden, Michael

This is the AmeriFlux version of the carbon flux data for the site US-CZ2 Sierra Critical Zone, Sierra Transect, Ponderosa Pine Forest, Soaproot Saddle. Site Description - Half hourly data are available at https://www.ess.uci.edu/~california/. This site is one of four Southern Sierra Critical Zone Observatory flux towers operated along an elevation gradient (sites are USCZ1, USCZ2, USCZ3 and USCZ4). This site is an oak/pine forest, with occasional thinning and wildfire, a prescribed understory burn ~2012, and severe drought and ~80% canopy mortality in 2011-15

Simplest bifurcation diagrams for monotone families of vector fields on a torus

NASA Astrophysics Data System (ADS)

Baesens, C.; MacKay, R. S.

2018-06-01

In part 1, we prove that the bifurcation diagram for a monotone two-parameter family of vector fields on a torus has to be at least as complicated as the conjectured simplest one proposed in Baesens et al (1991 Physica D 49 387–475). To achieve this, we define ‘simplest’ by sequentially minimising the numbers of equilibria, Bogdanov–Takens points, closed curves of centre and of neutral saddle, intersections of curves of centre and neutral saddle, Reeb components, other invariant annuli, arcs of rotational homoclinic bifurcation of horizontal homotopy type, necklace points, contractible periodic orbits, points of neutral horizontal homoclinic bifurcation and half-plane fan points. We obtain two types of simplest case, including that initially proposed. In part 2, we analyse the bifurcation diagram for an explicit monotone family of vector fields on a torus and prove that it has at most two equilibria, precisely four Bogdanov–Takens points, no closed curves of centre nor closed curves of neutral saddle, at most two Reeb components, precisely four arcs of rotational homoclinic connection of ‘horizontal’ homotopy type, eight horizontal saddle-node loop points, two necklace points, four points of neutral horizontal homoclinic connection, and two half-plane fan points, and there is no simultaneous existence of centre and neutral saddle, nor contractible homoclinic connection to a neutral saddle. Furthermore, we prove that all saddle-nodes, Bogdanov–Takens points, non-neutral and neutral horizontal homoclinic bifurcations are non-degenerate and the Hopf condition is satisfied for all centres. We also find it has four points of degenerate Hopf bifurcation. It thus provides an example of a family satisfying all the assumptions of part 1 except the one of at most one contractible periodic orbit.
First-principles investigation of point defect and atomic diffusion in Al2Ca

NASA Astrophysics Data System (ADS)

Tian, Xiao; Wang, Jia-Ning; Wang, Ya-Ping; Shi, Xue-Feng; Tang, Bi-Yu

2017-04-01

Point defects and atomic diffusion in Al2Ca have been studied from first-principles calculations within density functional framework. After formation energy and relative stability of point defects are investigated, several predominant diffusion processes in Al2Ca are studied, including sublattice one-step mechanism, 3-jump vacancy cycles and antistructure sublattice mechanism. The associated energy profiles are calculated with climbing image nudged elastic band (CI-NEB) method, then the saddle points and activation barriers during atomic diffusion are further determined. The resulted activation barriers show that both Al and Ca can diffuse mainly mediated by neighbor vacancy on their own sublattice. 3-jump cycle mechanism mediated by VCa may make some contribution to the overall Al diffusion. And antistructure (AS) sublattice mechanism can also play an important role in Ca atomic diffusion owing to the moderate activation barrier.
Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

DOE PAGES

Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; ...

2016-11-11

Here, a search for Pauli-exclusion-principle-violating K α electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8 × 10 30 s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8 × 10 30 s at 90% C.L. Itmore » is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.« less
Ideal Weyl points and helicoid surface states in artificial photonic crystal structures.

PubMed

Yang, Biao; Guo, Qinghua; Tremain, Ben; Liu, Rongjuan; Barr, Lauren E; Yan, Qinghui; Gao, Wenlong; Liu, Hongchao; Xiang, Yuanjiang; Chen, Jing; Fang, Chen; Hibbins, Alastair; Lu, Ling; Zhang, Shuang

2018-03-02

Weyl points are the crossings of linearly dispersing energy bands of three-dimensional crystals, providing the opportunity to explore a variety of intriguing phenomena such as topologically protected surface states and chiral anomalies. However, the lack of an ideal Weyl system in which the Weyl points all exist at the same energy and are separated from any other bands poses a serious limitation to the further development of Weyl physics and potential applications. By experimentally characterizing a microwave photonic crystal of saddle-shaped metallic coils, we observed ideal Weyl points that are related to each other through symmetry operations. Topological surface states exhibiting helicoidal structure have also been demonstrated. Our system provides a photonic platform for exploring ideal Weyl systems and developing possible topological devices. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
Conjugate gradient filtering of instantaneous normal modes, saddles on the energy landscape, and diffusion in liquids.

PubMed

Chowdhary, J; Keyes, T

2002-02-01

Instantaneous normal modes (INM's) are calculated during a conjugate-gradient (CG) descent of the potential energy landscape, starting from an equilibrium configuration of a liquid or crystal. A small number (approximately equal to 4) of CG steps removes all the Im-omega modes in the crystal and leaves the liquid with diffusive Im-omega which accurately represent the self-diffusion constant D. Conjugate gradient filtering appears to be a promising method, applicable to any system, of obtaining diffusive modes and facilitating INM theory of D. The relation of the CG-step dependent INM quantities to the landscape and its saddles is discussed.
THz-waves channeling in a monolithic saddle-coil for Dynamic Nuclear Polarization enhanced NMR

NASA Astrophysics Data System (ADS)

Macor, A.; de Rijk, E.; Annino, G.; Alberti, S.; Ansermet, J.-Ph.

2011-10-01

A saddle coil manufactured by electric discharge machining (EDM) from a solid piece of copper has recently been realized at EPFL for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance experiments (DNP-NMR) at 9.4 T. The corresponding electromagnetic behavior of radio-frequency (400 MHz) and THz (263 GHz) waves were studied by numerical simulation in various measurement configurations. Moreover, we present an experimental method by which the results of the THz-wave numerical modeling are validated. On the basis of the good agreement between numerical and experimental results, we conducted by numerical simulation a systematic analysis on the influence of the coil geometry and of the sample properties on the THz-wave field, which is crucial in view of the optimization of DNP-NMR in solids.
Road guide to geological points of interest on the island of Hawaii

NASA Technical Reports Server (NTRS)

Stearns, H. T.; Macdonald, G. A.; Greeley, R.

1974-01-01

This road guide briefly describes the points of geologic interest along the main roads on Hawaii. It begins at Hilo and proceeds around the island in a clockwise direction on State Route 11 to Kailua, then returns to Hilo on State Route 19 to Hilo via Waimea, with side excursions on the other principal roads. Minimum excursion time is two days, allowing only very brief time for the various stops. The return to Hilo from Waimea can be made via Route 19 along the Hamakua Coast (wet, leeward side of island, displaying typical tropical erosion) or via Route 20 over the Humuula Saddle (high, relatively dry and cool; young volcanic features).
Active shielding of cylindrical saddle-shaped coils: application to wire-wound RF coils for very low field NMR and MRI.

PubMed

Bidinosti, C P; Kravchuk, I S; Hayden, M E

2005-11-01

We provide an exact expression for the magnetic field produced by cylindrical saddle-shaped coils and their ideal shield currents in the low-frequency limit. The stream function associated with the shield surface current is also determined. The results of the analysis are useful for the design of actively shielded radio-frequency (RF) coils. Examples pertinent to very low field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are presented and discussed.
THz-waves channeling in a monolithic saddle-coil for Dynamic Nuclear Polarization enhanced NMR.

PubMed

Macor, A; de Rijk, E; Annino, G; Alberti, S; Ansermet, J-Ph

2011-10-01

A saddle coil manufactured by electric discharge machining (EDM) from a solid piece of copper has recently been realized at EPFL for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance experiments (DNP-NMR) at 9.4 T. The corresponding electromagnetic behavior of radio-frequency (400 MHz) and THz (263 GHz) waves were studied by numerical simulation in various measurement configurations. Moreover, we present an experimental method by which the results of the THz-wave numerical modeling are validated. On the basis of the good agreement between numerical and experimental results, we conducted by numerical simulation a systematic analysis on the influence of the coil geometry and of the sample properties on the THz-wave field, which is crucial in view of the optimization of DNP-NMR in solids. Copyright © 2011 Elsevier Inc. All rights reserved.
Comprehensive mechanism and structure-sensitivity of ethanol oxidation on platinum: new transition-state searching method for resolving the complex reaction network.

PubMed

Wang, Hui-Fang; Liu, Zhi-Pan

2008-08-20

Ethanol oxidation on Pt is a typical multistep and multiselectivity heterogeneous catalytic process. A comprehensive understanding of this fundamental reaction would greatly benefit design of catalysts for use in direct ethanol fuel cells and the degradation of biomass-derived oxygenates. In this work, the reaction network of ethanol oxidation on different Pt surfaces, including close-packed Pt{111}, stepped Pt{211}, and open Pt{100}, is explored thoroughly with an efficient reaction path searching method, which integrates our new transition-state searching technique with periodic density functional theory calculations. Our new technique enables the location of the transition state and saddle points for most surface reactions simply and efficiently by optimization of local minima. We show that the selectivity of ethanol oxidation on Pt depends markedly on the surface structure, which can be attributed to the structure-sensitivity of two key reaction steps: (i) the initial dehydrogenation of ethanol and (ii) the oxidation of acetyl (CH3CO). On open surface sites, ethanol prefers C-C bond cleavage via strongly adsorbed intermediates (CH2CO or CHCO), which leads to complete oxidation to CO2. However, only partial oxidizations to CH3CHO and CH3COOH occur on Pt{111}. Our mechanism points out that the open surface Pt{100} is the best facet to fully oxidize ethanol at low coverages, which sheds light on the origin of the remarkable catalytic performance of Pt tetrahexahedra nanocrystals found recently. The physical origin of the structure-selectivity is rationalized in terms of both thermodynamics and kinetics. Two fundamental quantities that dictate the selectivity of ethanol oxidation are identified: (i) the ability of surface metal atoms to bond with unsaturated C-containing fragments and (ii) the relative stability of hydroxyl at surface atop sites with respect to other sites.
Searching for tipping points in Pleistocene climate: Are they real? Are they portents for the future?

NASA Astrophysics Data System (ADS)

Mix, A. C.

2015-12-01

Paleoscientists seek fundamental knowledge of Earth systems, and have unique views of system dynamics on the timescales longer than recent observations. This is important, because some processes that may control the trajectory of change in the not-so-distant future are not well illustrated or constrained in the short history of instrumental observations; paleo data offer our only observational window on these longer scales. But paleo vision is also a bit blurry, and sometimes biased. It matters how we approach the records to focus on the right things, and it matters how we communicate our insights so that we can teach models to approximate real Earth system behaviors. In the six decades since Cesare Emiliani set us on the path of quantitative observational paleoscience, we've observed more and more. Each year brings more "proxies," more sites, more resolution, and the more we look the more we find interpretable signals. This data complexity makes the paleo literature daunting to outsiders; it is hard to get past the stories. Most of our narratives are grounded in linear systems, focusing on forcing and response, and we data generators struggle to infer even modest nonlinearity. But the concept of massive nonlinearity, tipping points, has recently entered the public consciousness, and the search is on anew for such events in paleo data. The reality of tipping points as well as the processes that may drive such events are not yet fully clear, but the search is essential because if humanity does indeed push the Earth system across an irreversible tipping point into a new state, we need to know how this might play out and over what time frames. Can we really learn about such occurrences, and the processes that control them, in paleo records? Do we need to think about the past differently? Will this change how we think about the future? Will it inform what we do about the future? Emiliani thought it should. This lecture will explore how.
Effect of rider experience and evaluator expertise on subjective grading of lameness in sound and unsound sports horses under saddle.

PubMed

Marqués, Fernando J; Waldner, Cheryl; Reed, Stephen; Autet, Fernando; Corbeil, Louise; Campbell, John

2014-04-01

The primary objective of this study was to investigate whether rider experience influences the assessment and grading of lameness in horses based on under-saddle gait analysis. Thirteen adult sports horses in active training were included in the study. After a baseline lameness and neurologic examination by the principal investigators, horses were videotaped while being ridden by an experienced and a less experienced rider. A 3-minute video was made for each horse and rider and 26 videos were randomly ordered and compiled on a DVD. Veterinarians with different levels of experience in evaluating lameness and veterinary students viewed the DVD and assigned a lameness score to each horse/rider combination. In a model accounting for the expertise of the evaluator, there was no difference in overall lameness scores between experienced and less experienced riders. This result was consistent for both sound and unsound horses. The overall lameness scores reported by specialists and students, however, differed significantly. The lameness score reported by the study participants while the horse was ridden was significantly associated with the subjective baseline lameness assessment reported by the principal investigators for the same limb when the horse was not under saddle. Additional work is necessary to determine whether riders with even lower skill levels would further alter the balance and motion pattern of the horse and have more influence on subjective grading of lameness.
Effect of rider experience and evaluator expertise on subjective grading of lameness in sound and unsound sports horses under saddle

PubMed Central

Marqués, Fernando J.; Waldner, Cheryl; Reed, Stephen; Autet, Fernando; Corbeil, Louise; Campbell, John

2014-01-01

The primary objective of this study was to investigate whether rider experience influences the assessment and grading of lameness in horses based on under-saddle gait analysis. Thirteen adult sports horses in active training were included in the study. After a baseline lameness and neurologic examination by the principal investigators, horses were videotaped while being ridden by an experienced and a less experienced rider. A 3-minute video was made for each horse and rider and 26 videos were randomly ordered and compiled on a DVD. Veterinarians with different levels of experience in evaluating lameness and veterinary students viewed the DVD and assigned a lameness score to each horse/rider combination. In a model accounting for the expertise of the evaluator, there was no difference in overall lameness scores between experienced and less experienced riders. This result was consistent for both sound and unsound horses. The overall lameness scores reported by specialists and students, however, differed significantly. The lameness score reported by the study participants while the horse was ridden was significantly associated with the subjective baseline lameness assessment reported by the principal investigators for the same limb when the horse was not under saddle. Additional work is necessary to determine whether riders with even lower skill levels would further alter the balance and motion pattern of the horse and have more influence on subjective grading of lameness. PMID:24688169
SEARCHES FOR POINT-LIKE AND EXTENDED NEUTRINO SOURCES CLOSE TO THE GALACTIC CENTER USING THE ANTARES NEUTRINO TELESCOPE

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

Adrián-Martínez, S.; Ardid, M.; Bou-Cabo, M.

2014-05-01

A search for cosmic neutrino sources using six years of data collected by the ANTARES neutrino telescope has been performed. Clusters of muon neutrinos over the expected atmospheric background have been looked for. No clear signal has been found. The most signal-like accumulation of events is located at equatorial coordinates R.A. = –46.°8 and decl. = –64.°9 and corresponds to a 2.2σ background fluctuation. In addition, upper limits on the flux normalization of an E {sup –2} muon neutrino energy spectrum have been set for 50 pre-selected astrophysical objects. Finally, motivated by an accumulation of seven events relatively close tomore » the Galactic Center in the recently reported neutrino sample of the IceCube telescope, a search for point sources in a broad region around this accumulation has been carried out. No indication of a neutrino signal has been found in the ANTARES data and upper limits on the flux normalization of an E {sup –2} energy spectrum of neutrinos from point sources in that region have been set. The 90% confidence level upper limits on the muon neutrino flux normalization vary between 3.5 and 5.1 × 10{sup –8} GeV cm{sup –2} s{sup –1}, depending on the exact location of the source.« less
Saddle-node bifurcation to jammed state for quasi-one-dimensional counter-chemotactic flow.

PubMed

Fujii, Masashi; Awazu, Akinori; Nishimori, Hiraku

2010-07-01

The transition of a counter-chemotactic particle flow from a free-flow state to a jammed state in a quasi-one-dimensional path is investigated. One of the characteristic features of such a flow is that the constituent particles spontaneously form a cluster that blocks the path, called a path-blocking cluster (PBC), and causes a jammed state when the particle density is greater than a threshold value. Near the threshold value, the PBC occasionally collapses on itself to recover the free flow. In other words, the time evolution of the size of the PBC governs the flux of a counter-chemotactic flow. In this Rapid Communication, on the basis of numerical results of a stochastic cellular automata (SCA) model, we introduce a Langevin equation model for the size evolution of the PBC that reproduces the qualitative characteristics of the SCA model. The results suggest that the emergence of the jammed state in a quasi-one-dimensional counterflow is caused by a saddle-node bifurcation.
Will an "island" population of voles be recolonized if eradicated? Insights from molecular genetic analyses

USGS Publications Warehouse

Miller, Mark P.; Haig, Susan M.; Ledig, David B.; Vander Heyden, Madeleine F.; Bennett, Gregory

2011-01-01

We performed genetic analyses of Microtus longicaudus populations within the Crook Point Unit of the Oregon Islands National Wildlife Refuge. A M. longicaudus population at Saddle Rock (located approx. 65 m off-shore from the Crook Point mainland) is suspected to be partially responsible for declines of a Leach's storm-petrel colony at this important nesting site. Using Amplified Fragment Length Polymorphism markers and mitochondrial DNA, we illustrate that Saddle Rock and Crook Point function as separate island and mainland populations despite their close proximity. In addition to genetic structure, we also observed reduced genetic diversity at Saddle Rock, suggesting that little individual movement occurs between populations. If local resource managers decide to perform an eradication at Saddle Rock, we conclude that immediate recolonization of the island by M. longicaudus would be unlikely. Because M. longicaudus is native to Oregon, we also consider the degree with which the differentiation of Saddle Rock signifies the presence of a unique entity that warrants conservation rather than eradication. ?? The Wildlife Society, 2011.
Communication: A new ab initio potential energy surface for HCl-H2O, diffusion Monte Carlo calculations of D0 and a delocalized zero-point wavefunction.

PubMed

Mancini, John S; Bowman, Joel M

2013-03-28

We report a global, full-dimensional, ab initio potential energy surface describing the HCl-H2O dimer. The potential is constructed from a permutationally invariant fit, using Morse-like variables, to over 44,000 CCSD(T)-F12b∕aug-cc-pVTZ energies. The surface describes the complex and dissociated monomers with a total RMS fitting error of 24 cm(-1). The normal modes of the minima, low-energy saddle point and separated monomers, the double minimum isomerization pathway and electronic dissociation energy are accurately described by the surface. Rigorous quantum mechanical diffusion Monte Carlo (DMC) calculations are performed to determine the zero-point energy and wavefunction of the complex and the separated fragments. The calculated zero-point energies together with a De value calculated from CCSD(T) with a complete basis set extrapolation gives a D0 value of 1348 ± 3 cm(-1), in good agreement with the recent experimentally reported value of 1334 ± 10 cm(-1) [B. E. Casterline, A. K. Mollner, L. C. Ch'ng, and H. Reisler, J. Phys. Chem. A 114, 9774 (2010)]. Examination of the DMC wavefunction allows for confident characterization of the zero-point geometry to be dominant at the C(2v) double-well saddle point and not the C(s) global minimum. Additional support for the delocalized zero-point geometry is given by numerical solutions to the 1D Schrödinger equation along the imaginary-frequency out-of-plane bending mode, where the zero-point energy is calculated to be 52 cm(-1) above the isomerization barrier. The D0 of the fully deuterated isotopologue is calculated to be 1476 ± 3 cm(-1), which we hope will stand as a benchmark for future experimental work.
Magnetotelluric and audiomagnetotelluric groundwater survey along the Humu'ula portion of Saddle Road near and around the Pohakuloa Training Area, Hawaii

USGS Publications Warehouse

Pierce, Herbert A.; Thomas, Donald M.

2009-01-01

The Pohakuloa Training Area (PTA), operated by the U.S. Army on the Big Island of Hawaii, is in need of a reliable potable water supply to sustain ongoing operations by staff and trainees. In an effort to acquire baseline hydrologic data with which to develop a plan for providing that water, a series of magnetotelluric (MT) geophysical surveys was performed that spanned the Mauna Loa/Mauna Kea Saddle region of Hawaii Island. These surveys provided electrical resistivity profiles and resistivity maps at several elevations along the axis of the field measurements that can be interpreted to yield information on the depth to the water table. In 2004 a preliminary sequence of 23 audiomagnetotelluric (AMT) soundings was collected along Saddle Road extending from the Waikii Ranch area, west of the PTA, to Department of Hawaiian Home Lands Humu'ula properties east of the Mauna Kea access road. The results of those soundings showed that highly resistive rocks, consistent with dry basalts, were present to depths of at least one kilometer, the maximum depth to which the AMT technique can reliably reach in Hawaii's rocks. A second survey was conducted in 2008 using MT instruments capable of recovering resistivity data to depths of several kilometers below sea level where saturated formations are known to exist. A total of 30 MT soundings was performed along a roughly east to west transect that extended from the (recently acquired) Keamuku PTA lands on the west to as far as the County of Hawaii's upper Kaumana water supply well to the east. Inversion and processing of the field data yielded an electrical cross-section following the Saddle that roughly parallels the geologic contact between the Mauna Kea and Mauna Loa lavas. Several additional electrical sections were constructed normal to the main transect to investigate the three-dimensional nature of the contact. These resistivity data and models suggest that the elevation of saturated rock in places are 400 to 600 meters
DRAFT One Year Extension of the Short-Term National Product Waiver for Stainless Steel Nuts and Bolts used in Pipe Couplings, Restraints, Joints, Flanges and Saddles for State Revolving Fund Projects

EPA Pesticide Factsheets

DRAFT one year extension of the short-term national product waiver for stainless steel nuts and bolts used in pipe couplings, restraints, joints, flanges and saddles for State Revolving Fund projects.
Two-terminal conductance fluctuations in the integer quantum Hall regime

NASA Astrophysics Data System (ADS)

Ho, Chang-Ming

1999-09-01

Motivated by recent experiments on the conductance fluctuations in mesoscopic integer quantum Hall systems, we consider a model in which the Coulomb interactions are incorporated into the picture of edge-state transport through a single saddle point. The occupancies of classical localized states in the two-dimensional electron system change due to the interactions between electrons when the gate voltage on top of the device is varied. The electrostatic potential between the localized states and the saddle point causes fluctuations of the saddle-point potential and thus fluctuations of the transmission probability of edge states. This simple model is studied numerically and compared with the observation.

Slow light effect with high group index and wideband by saddle-like mode in PC-CROW

NASA Astrophysics Data System (ADS)

Wan, Yong; Jiang, Li-Jun; Xu, Sheng; Li, Meng-Xue; Liu, Meng-Nan; Jiang, Cheng-Yi; Yuan, Feng

2018-04-01

Slow light with high group index and wideband is achieved in photonic crystal coupled-resonator optical waveguides (PC-CROWs). According to the eye-shaped scatterers and various microcavities, saddle-like curves between the normalized frequency f and wave number k can be obtained by adjusting the parameters of the scatterers, parameters of the coupling microcavities, and positions of the scatterers. Slow light with decent flat band and group index can then be achieved by optimizing the parameters. Simulations prove that the maximal value of the group index is > 104, and the normalized delay bandwidth product within a new varying range of n g > 102 or n g > 103 can be a new and effective criterion of evaluation for the slow light in PC-CROWs.
A finite difference Davidson procedure to sidestep full ab initio hessian calculation: Application to characterization of stationary points and transition state searches

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

Sharada, Shaama Mallikarjun; Bell, Alexis T., E-mail: mhg@bastille.cchem.berkeley.edu, E-mail: bell@cchem.berkeley.edu; Head-Gordon, Martin, E-mail: mhg@bastille.cchem.berkeley.edu, E-mail: bell@cchem.berkeley.edu

2014-04-28

The cost of calculating nuclear hessians, either analytically or by finite difference methods, during the course of quantum chemical analyses can be prohibitive for systems containing hundreds of atoms. In many applications, though, only a few eigenvalues and eigenvectors, and not the full hessian, are required. For instance, the lowest one or two eigenvalues of the full hessian are sufficient to characterize a stationary point as a minimum or a transition state (TS), respectively. We describe here a method that can eliminate the need for hessian calculations for both the characterization of stationary points as well as searches for saddlemore » points. A finite differences implementation of the Davidson method that uses only first derivatives of the energy to calculate the lowest eigenvalues and eigenvectors of the hessian is discussed. This method can be implemented in conjunction with geometry optimization methods such as partitioned-rational function optimization (P-RFO) to characterize stationary points on the potential energy surface. With equal ease, it can be combined with interpolation methods that determine TS guess structures, such as the freezing string method, to generate approximate hessian matrices in lieu of full hessians as input to P-RFO for TS optimization. This approach is shown to achieve significant cost savings relative to exact hessian calculation when applied to both stationary point characterization as well as TS optimization. The basic reason is that the present approach scales one power of system size lower since the rate of convergence is approximately independent of the size of the system. Therefore, the finite-difference Davidson method is a viable alternative to full hessian calculation for stationary point characterization and TS search particularly when analytical hessians are not available or require substantial computational effort.« less
Stress concentration factors at saddle and crown positions on the central brace of two-planar welded CHS DKT-connections

NASA Astrophysics Data System (ADS)

Ahmadi, Hamid; Lotfollahi-Yaghin, Mohammad Ali; Aminfar, Mohammad H.

2012-03-01

A set of parametric stress analyses was carried out for two-planar tubular DKT-joints under different axial loading conditions. The analysis results were used to present general remarks on the effects of the geometrical parameters on stress concentration factors (SCFs) at the inner saddle, outer saddle, and crown positions on the central brace. Based on results of finite element (FE) analysis and through nonlinear regression analysis, a new set of SCF parametric equations was established for fatigue design purposes. An assessment study of equations was conducted against the experimental data and original SCF database. The satisfaction of acceptance criteria proposed by the UK Department of Energy (UK DoE) was also checked. Results of parametric study showed that highly remarkable differences exist between the SCF values in a multi-planar DKT-joint and the corresponding SCFs in an equivalent uni-planar KT-joint having the same geometrical properties. It can be clearly concluded from this observation that using the equations proposed for uni-planar KT-connections to compute the SCFs in multi-planar DKT-joints will lead to either considerably under-predicting or over-predicting results. Hence, it is necessary to develop SCF formulae specially designed for multi-planar DKT-joints. Good results of equation assessment according to UK DoE acceptance criteria, high values of correlation coefficients, and the satisfactory agreement between the predictions of the proposed equations and the experimental data guarantee the accuracy of the equations. Therefore, the developed equations can be reliably used for fatigue design of offshore structures.
Bifurcation of Limit Cycles in a Near-Hamiltonian System with a Cusp of Order Two and a Saddle

NASA Astrophysics Data System (ADS)

Bakhshalizadeh, Ali; Zangeneh, Hamid R. Z.; Kazemi, Rasool

In this paper, the asymptotic expansion of first-order Melnikov function of a heteroclinic loop connecting a cusp of order two and a hyperbolic saddle for a planar near-Hamiltonian system is given. Next, we consider the limit cycle bifurcations of a hyper-elliptic Liénard system with this kind of heteroclinic loop and study the least upper bound of limit cycles bifurcated from the period annulus inside the heteroclinic loop, from the heteroclinic loop itself and the center. We find that at most three limit cycles can be bifurcated from the period annulus, also we present different distributions of bifurcated limit cycles.
Visual search and coordination changes in response to video and point-light demonstrations without KR.

PubMed

Horn, R R; Williams, A M; Scott, M A; Hodges, N J

2005-07-01

The authors examined the observational learning of 24 participants whom they constrained to use the model by removing intrinsic visual knowledge of results (KR). Matched participants assigned to video (VID), point-light (PL), and no-model (CON) groups performed a soccer-chipping task in which vision was occluded at ball contact. Pre- and posttests were interspersed with alternating periods of demonstration and acquisition. The authors assessed delayed retention 2-3 days later. In support of the visual perception perspective, the participants who observed the models showed immediate and enduring changes to more closely imitate the model's relative motion. While observing the demonstration, the PL group participants were more selective in their visual search than were the VID group participants but did not perform more accurately or learn more.
Search for Point Sources of Ultra-High-Energy Cosmic Rays above 4.0 × 1019 eV Using a Maximum Likelihood Ratio Test

NASA Astrophysics Data System (ADS)

Abbasi, R. U.; Abu-Zayyad, T.; Amann, J. F.; Archbold, G.; Atkins, R.; Bellido, J. A.; Belov, K.; Belz, J. W.; Ben-Zvi, S. Y.; Bergman, D. R.; Boyer, J. H.; Burt, G. W.; Cao, Z.; Clay, R. W.; Connolly, B. M.; Dawson, B. R.; Deng, W.; Farrar, G. R.; Fedorova, Y.; Findlay, J.; Finley, C. B.; Hanlon, W. F.; Hoffman, C. M.; Holzscheiter, M. H.; Hughes, G. A.; Hüntemeyer, P.; Jui, C. C. H.; Kim, K.; Kirn, M. A.; Knapp, B. C.; Loh, E. C.; Maestas, M. M.; Manago, N.; Mannel, E. J.; Marek, L. J.; Martens, K.; Matthews, J. A. J.; Matthews, J. N.; O'Neill, A.; Painter, C. A.; Perera, L.; Reil, K.; Riehle, R.; Roberts, M. D.; Sasaki, M.; Schnetzer, S. R.; Seman, M.; Simpson, K. M.; Sinnis, G.; Smith, J. D.; Snow, R.; Sokolsky, P.; Song, C.; Springer, R. W.; Stokes, B. T.; Thomas, J. R.; Thomas, S. B.; Thomson, G. B.; Tupa, D.; Westerhoff, S.; Wiencke, L. R.; Zech, A.

2005-04-01

We present the results of a search for cosmic-ray point sources at energies in excess of 4.0×1019 eV in the combined data sets recorded by the Akeno Giant Air Shower Array and High Resolution Fly's Eye stereo experiments. The analysis is based on a maximum likelihood ratio test using the probability density function for each event rather than requiring an a priori choice of a fixed angular bin size. No statistically significant clustering of events consistent with a point source is found.
Evolutionary pattern search algorithms

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

Hart, W.E.

1995-09-19

This paper defines a class of evolutionary algorithms called evolutionary pattern search algorithms (EPSAs) and analyzes their convergence properties. This class of algorithms is closely related to evolutionary programming, evolutionary strategie and real-coded genetic algorithms. EPSAs are self-adapting systems that modify the step size of the mutation operator in response to the success of previous optimization steps. The rule used to adapt the step size can be used to provide a stationary point convergence theory for EPSAs on any continuous function. This convergence theory is based on an extension of the convergence theory for generalized pattern search methods. An experimentalmore » analysis of the performance of EPSAs demonstrates that these algorithms can perform a level of global search that is comparable to that of canonical EAs. We also describe a stopping rule for EPSAs, which reliably terminated near stationary points in our experiments. This is the first stopping rule for any class of EAs that can terminate at a given distance from stationary points.« less
A Genealogy of Convex Solids Via Local and Global Bifurcations of Gradient Vector Fields

NASA Astrophysics Data System (ADS)

Domokos, Gábor; Holmes, Philip; Lángi, Zsolt

2016-12-01

Three-dimensional convex bodies can be classified in terms of the number and stability types of critical points on which they can balance at rest on a horizontal plane. For typical bodies, these are non-degenerate maxima, minima, and saddle points, the numbers of which provide a primary classification. Secondary and tertiary classifications use graphs to describe orbits connecting these critical points in the gradient vector field associated with each body. In previous work, it was shown that these classifications are complete in that no class is empty. Here, we construct 1- and 2-parameter families of convex bodies connecting members of adjacent primary and secondary classes and show that transitions between them can be realized by codimension 1 saddle-node and saddle-saddle (heteroclinic) bifurcations in the gradient vector fields. Our results indicate that all combinatorially possible transitions can be realized in physical shape evolution processes, e.g., by abrasion of sedimentary particles.
A Theoretical Framework for Lagrangian Descriptors

NASA Astrophysics Data System (ADS)

Lopesino, C.; Balibrea-Iniesta, F.; García-Garrido, V. J.; Wiggins, S.; Mancho, A. M.

This paper provides a theoretical background for Lagrangian Descriptors (LDs). The goal of achieving rigorous proofs that justify the ability of LDs to detect invariant manifolds is simplified by introducing an alternative definition for LDs. The definition is stated for n-dimensional systems with general time dependence, however we rigorously prove that this method reveals the stable and unstable manifolds of hyperbolic points in four particular 2D cases: a hyperbolic saddle point for linear autonomous systems, a hyperbolic saddle point for nonlinear autonomous systems, a hyperbolic saddle point for linear nonautonomous systems and a hyperbolic saddle point for nonlinear nonautonomous systems. We also discuss further rigorous results which show the ability of LDs to highlight additional invariants sets, such as n-tori. These results are just a simple extension of the ergodic partition theory which we illustrate by applying this methodology to well-known examples, such as the planar field of the harmonic oscillator and the 3D ABC flow. Finally, we provide a thorough discussion on the requirement of the objectivity (frame-invariance) property for tools designed to reveal phase space structures and their implications for Lagrangian descriptors.
Ideal strength of bcc molybdenum and niobium

NASA Astrophysics Data System (ADS)

Luo, Weidong; Roundy, D.; Cohen, Marvin L.; Morris, J. W.

2002-09-01

The behavior of bcc Mo and Nb under large strain was investigated using the ab initio pseudopotential density-functional method. We calculated the ideal shear strength for the {211}<111> and {011}<111> slip systems and the ideal tensile strength in the <100> direction, which are believed to provide the minimum shear and tensile strengths. As either material is sheared in either of the two systems, it evolves toward a stress-free tetragonal structure that defines a saddle point in the strain-energy surface. The inflection point on the path to this tetragonal ``saddle-point'' structure sets the ideal shear strength. When either material is strained in tension along <100>, it initially follows the tetragonal, ``Bain,'' path toward a stress-free fcc structure. However, before the strained crystal reaches fcc, its symmetry changes from tetragonal to orthorhombic; on continued strain it evolves toward the same tetragonal saddle point that is reached in shear. In Mo, the symmetry break occurs after the point of maximum tensile stress has been passed, so the ideal strength is associated with the fcc extremum as in W. However, a Nb crystal strained in <100> becomes orthorhombic at tensile stress below the ideal strength. The ideal tensile strength of Nb is associated with the tetragonal saddle point and is caused by failure in shear rather than tension. In dimensionless form, the ideal shear and tensile strengths of Mo (τ*=τm/G111=0.12, σ*=σm/E100=0.078) are essentially identical to those previously calculated for W. Nb is anomalous. Its dimensionless shear strength is unusually high, τ*=0.15, even though the saddle-point structure that causes it is similar to that in Mo and W, while its dimensionless tensile strength, σ*=0.079, is almost the same as that of Mo and W, even though the saddle-point structure is quite different.
Origins of Coordinate Searching.

ERIC Educational Resources Information Center

Kilgour, Frederick G.

1997-01-01

Reviews the origins of post-coordinate searching and emphasizes that the focal point should be on the searcher, not on the item being indexed. Highlights include the history of the term information retrieval; edge notched punch cards; the "peek-a-boo" system; the Uniterm system; and using computers to search for information. (LRW)
A free boundary approach to the Rosensweig instability of ferrofluids

NASA Astrophysics Data System (ADS)

Parini, Enea; Stylianou, Athanasios

2018-04-01

We establish the existence of saddle points for a free boundary problem describing the two-dimensional free surface of a ferrofluid undergoing normal field instability. The starting point is the ferrohydrostatic equations for the magnetic potentials in the ferrofluid and air, and the function describing their interface. These constitute the strong form for the Euler-Lagrange equations of a convex-concave functional, which we extend to include interfaces that are not necessarily graphs of functions. Saddle points are then found by iterating the direct method of the calculus of variations and applying classical results of convex analysis. For the existence part, we assume a general nonlinear magnetization law; for a linear law, we also show, via convex duality, that the saddle point is a constrained minimizer of the relevant energy functional.
New Architectures for Presenting Search Results Based on Web Search Engines Users Experience

ERIC Educational Resources Information Center

Martinez, F. J.; Pastor, J. A.; Rodriguez, J. V.; Lopez, Rosana; Rodriguez, J. V., Jr.

2011-01-01

Introduction: The Internet is a dynamic environment which is continuously being updated. Search engines have been, currently are and in all probability will continue to be the most popular systems in this information cosmos. Method: In this work, special attention has been paid to the series of changes made to search engines up to this point,…
IceCube results from point-like source searches using 6 years of through-going muon data

NASA Astrophysics Data System (ADS)

Coenders, Stefan

2016-04-01

The IceCube Neutrino Observatory located at the geographic South Pole was designed to study and discover high energy neutrinos coming from both galactic and extra-galactic astrophysical sources. Track-like events induced by charged-current muon-neutrino interactions close to the IceCube detector give an angular resolution better than 1∘ above TeV energies. We present here the results of searches for point-like astrophysical neutrino sources on the full sky using 6 years of detector livetime, of which three years use the complete IceCube detector. Within 2000 days of detector livetime, IceCube is sensitive to a steady flux substantially below E2∂ϕ/∂E = 10-12 TeV cm-2 s-1 in the northern sky for neutrino energies above 10 TeV.
Stochastic dynamics in a two-dimensional oscillator near a saddle-node bifurcation

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

Inchiosa, M. E.; In, V.; Bulsara, A. R.

We study the oscillator equations describing a particular class of nonlinear amplifier, exemplified in this work by a two-junction superconducting quantum interference device. This class of dynamic system is described by a potential energy function that can admit minima (corresponding to stable solutions of the dynamic equations), or {open_quotes}running states{close_quotes} wherein the system is biased so that the potential minima disappear and the solutions display spontaneous oscillations. Just beyond the onset of the spontaneous oscillations, the system is known to show significantly enhanced sensitivity to very weak magnetic signals. The global phase space structure allows us to apply a centermore » manifold technique to approximate analytically the oscillatory behavior just past the (saddle-node) bifurcation and compute the oscillation period, which obeys standard scaling laws. In this regime, the dynamics can be represented by an {open_quotes}integrate-fire{close_quotes} model drawn from the computational neuroscience repertoire; in fact, we obtain an {open_quotes}interspike interval{close_quotes} probability density function and an associated power spectral density (computed via Renewal theory) that agree very well with the results obtained via numerical simulations. Notably, driving the system with one or more time sinusoids produces a noise-lowering injection locking effect and/or heterodyning.« less
Search for point-like sources of cosmic rays with energies above 1018.5 eV in the HiRes-I monocular data set

NASA Astrophysics Data System (ADS)

High-Resolution Fly'S Eye Collaboration; Abbai, R. U.; Abu-Zayyad, T.; Amann, J. F.; Archbold, G.; Belov, K.; Belz, J. W.; Benzvi, S.; Bergman, D. R.; Blake, S. A.; Cao, Z.; Connolly, B. M.; Deng, W.; Fedorova, Y.; Findlay, J.; Finley, C. B.; Gray, R. C.; Hanlon, W. F.; Hoffman, C. M.; Holzscheiter, M. H.; Hughes, G. A.; Hüntemeyer, P.; Jones, B. F.; Jui, C. C. H.; Kim, K.; Kirn, M. A.; Loh, E. C.; Maestas, M. M.; Manago, N.; Marek, L. J.; Martens, K.; Matthews, J. A. J.; Matthews, J. N.; Moore, S. A.; O'Neill, A.; Painter, C. A.; Perera, L.; Reil, K.; Riehle, R.; Rodriguez, D.; Roberts, M. D.; Sasaki, M.; Schnetzer, S. R.; Scott, L. M.; Sinnis, G.; Smith, J. D.; Sokolsky, P.; Song, C.; Springer, R. W.; Stokes, B. T.; Thomas, J. R.; Thomas, S. B.; Thomson, G. B.; Tupa, D.; Westerhoff, S.; Wiencke, L. R.; Zech, A.; Zhang, X.

2007-07-01

We report the results of a search for point-like deviations from isotropy in the arrival directions of ultra-high energy cosmic rays in the northern hemisphere. In the monocular data set collected by the High-Resolution Fly’s Eye, consisting of 1525 events with energy exceeding 1018.5 eV, we find no evidence for point-like excesses. We place a 90% c.l. upper limit of 0.8 hadronic cosmic rays/km2 yr on the flux from such sources for the northern hemisphere and place tighter limits as a function of position in the sky.
One-Meter Telescope in Kolonica Saddle - 4 Years of Operation

NASA Astrophysics Data System (ADS)

Kudzej, I.; Dubovsky, P. A.

2010-12-01

The actual technical status of 1 meter Vihorlat National Telescope (VNT) at Astronomical Observatory at Kolonica Saddle is presented. Cassegrain and Nasmyth focus, autoguiding system, computer controlled focusing and fine movements and other improvements achieved recently. For two channel photoelectric photometer the system of channels calibration based on artificial light source is described. For CCD camera FLI PL1001E actually installed in Cassegrain focus we presents transformation coefficients from our instrumental to international photometric BVRI system. The measurements were done during regular observations when good photometry of the constant field stars was available. Before FLI camera acquisition we used SBIG ST9 camera. Transformation coefficients for this instrument are presented as well. In the second part of the paper we presents results of variable stars observations with 1 meter telescope in recent four years. The first experimental electronic measurements were done in 2006. Both with CCD cameras and with two channel photoelectric photometer. Starting in 2007 the regular observing program is in operation. There are only few stars suitable for two channel photoelectric photometer observation. Generally the photometer is better when fast brightness changes (time scale of seconds) must be recorded. Thus the majority of observations is done with CCD detectors. We presents an brief overview of most important observing programs: long term monitoring of selected intermediate polars, eclipse observations of SW Sex stars. Occasional observing campaigns were performed on several interesting objects: OT J071126.0+440405, V603 Aql, V471 Tau eclipse timings, Z And in outburst.
Flood-inundation maps for the Saddle River in Ho-Ho-Kus Borough, the Village of Ridgewood, and Paramus Borough, New Jersey, 2013

USGS Publications Warehouse

Watson, Kara M.; Niemoczynski, Michal J.

2014-01-01

Digital flood-inundation maps for a 5.4-mile reach of the Saddle River in New Jersey from Hollywood Avenue in Ho-Ho-Kus Borough downstream through the Village of Ridgewood and Paramus Borough to the confluence with Hohokus Brook in the Village of Ridgewood were created by the U.S. Geological Survey (USGS) in cooperation with the New Jersey Department of Environmental Protection (NJDEP). The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage on the Saddle River at Ridgewood, New Jersey (station 01390500). Current conditions for estimating near real-time areas of inundation using USGS streamgage information may be obtained on the Internet at http://waterdata.usgs.gov/nwis/uv?site_no=01390500 or at the National Weather Services (NWS) Advanced Hydrologic Prediction Service (AHPS) at http://water.weather.gov/ahps2/hydrograph.php?wfo=okx&gage=rwdn4. In this study, flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated by using the most current stage-discharge relation (March 11, 2011) at the USGS streamgage 01390500, Saddle River at Ridgewood, New Jersey. The hydraulic model was then used to compute 10 water-surface profiles for flood stages at 1-foot (ft) intervals referenced to the streamgage datum, North American Vertical Datum of 1988 (NAVD 88), and ranging from 5 ft, the NWS “action and minor flood stage”, to 14 ft, which is the maximum extent of the stage-discharge rating and 0.6 ft higher than the highest recorded water level at the streamgage. The simulated water-surface profiles were then combined with a geographic information system 3-meter (9.84-ft) digital elevation model derived from Light Detection and Ranging (lidar) data in order to delineate the area flooded
Search of low-mass WIMPs with a p -type point contact germanium detector in the CDEX-1 experiment

NASA Astrophysics Data System (ADS)

Zhao, W.; Yue, Q.; Kang, K. J.; Cheng, J. P.; Li, Y. J.; Wong, H. T.; Lin, S. T.; Chang, J. P.; Chen, J. H.; Chen, Q. H.; Chen, Y. H.; Deng, Z.; Du, Q.; Gong, H.; Hao, X. Q.; He, H. J.; He, Q. J.; Huang, H. X.; Huang, T. R.; Jiang, H.; Li, H. B.; Li, J.; Li, J.; Li, J. M.; Li, X.; Li, X. Y.; Li, Y. L.; Lin, F. K.; Liu, S. K.; Lü, L. C.; Ma, H.; Ma, J. L.; Mao, S. J.; Qin, J. Q.; Ren, J.; Ren, J.; Ruan, X. C.; Sharma, V.; Shen, M. B.; Singh, L.; Singh, M. K.; Soma, A. K.; Su, J.; Tang, C. J.; Wang, J. M.; Wang, L.; Wang, Q.; Wu, S. Y.; Wu, Y. C.; Xianyu, Z. Z.; Xiao, R. Q.; Xing, H. Y.; Xu, F. Z.; Xu, Y.; Xu, X. J.; Xue, T.; Yang, L. T.; Yang, S. W.; Yi, N.; Yu, C. X.; Yu, H.; Yu, X. Z.; Zeng, M.; Zeng, X. H.; Zeng, Z.; Zhang, L.; Zhang, Y. H.; Zhao, M. G.; Zhou, Z. Y.; Zhu, J. J.; Zhu, W. B.; Zhu, X. Z.; Zhu, Z. H.; CDEX Collaboration

2016-05-01

The CDEX-1 experiment conducted a search of low-mass (<10 GeV /c2 ) weakly interacting massive particles dark matter at the China Jinping Underground Laboratory using a p-type point-contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware setup, detector characterization, data acquisition, and analysis procedures of this experiment. No excess of unidentified events is observed after the subtraction of the known background. Using 335.6 kg-days of data, exclusion constraints on the weakly interacting massive particle-nucleon spin-independent and spin-dependent couplings are derived.
Dynamics and Physiological Roles of Stochastic Firing Patterns Near Bifurcation Points

NASA Astrophysics Data System (ADS)

Jia, Bing; Gu, Huaguang

2017-06-01

Different stochastic neural firing patterns or rhythms that appeared near polarization or depolarization resting states were observed in biological experiments on three nervous systems, and closely matched those simulated near bifurcation points between stable equilibrium point and limit cycle in a theoretical model with noise. The distinct dynamics of spike trains and interspike interval histogram (ISIH) of these stochastic rhythms were identified and found to build a relationship to the coexisting behaviors or fixed firing frequency of four different types of bifurcations. Furthermore, noise evokes coherence resonances near bifurcation points and plays important roles in enhancing information. The stochastic rhythms corresponding to Hopf bifurcation points with fixed firing frequency exhibited stronger coherence degree and a sharper peak in the power spectrum of the spike trains than those corresponding to saddle-node bifurcation points without fixed firing frequency. Moreover, the stochastic firing patterns changed to a depolarization resting state as the extracellular potassium concentration increased for the injured nerve fiber related to pathological pain or static blood pressure level increased for aortic depressor nerve fiber, and firing frequency decreased, which were different from the physiological viewpoint that firing frequency increased with increasing pressure level or potassium concentration. This shows that rhythms or firing patterns can reflect pressure or ion concentration information related to pathological pain information. Our results present the dynamics of stochastic firing patterns near bifurcation points, which are helpful for the identification of both dynamics and physiological roles of complex neural firing patterns or rhythms, and the roles of noise.

Parallel Element Agglomeration Algebraic Multigrid and Upscaling Library

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

Barker, Andrew T.; Benson, Thomas R.; Lee, Chak Shing

ParELAG is a parallel C++ library for numerical upscaling of finite element discretizations and element-based algebraic multigrid solvers. It provides optimal complexity algorithms to build multilevel hierarchies and solvers that can be used for solving a wide class of partial differential equations (elliptic, hyperbolic, saddle point problems) on general unstructured meshes. Additionally, a novel multilevel solver for saddle point problems with divergence constraint is implemented.
Searching for the fastest dynamo: laminar ABC flows.

PubMed

Alexakis, Alexandros

2011-08-01

The growth rate of the dynamo instability as a function of the magnetic Reynolds number R(M) is investigated by means of numerical simulations for the family of the Arnold-Beltrami-Childress (ABC) flows and for two different forcing scales. For the ABC flows that are driven at the largest available length scale, it is found that, as the magnetic Reynolds number is increased: (a) The flow that results first in a dynamo is the 2 1/2-dimensional flow for which A=B and C=0 (and all permutations). (b) The second type of flow that results in a dynamo is the one for which A=B≃2C/5 (and permutations). (c) The most symmetric flow, A=B=C, is the third type of flow that results in a dynamo. (d) As R(M) is increased, the A=B=C flow stops being a dynamo and transitions from a local maximum to a third-order saddle point. (e) At larger R(M), the A=B=C flow reestablishes itself as a dynamo but remains a saddle point. (f) At the largest examined R(M), the growth rate of the 2 1/2-dimensional flows starts to decay, the A=B=C flow comes close to a local maximum again, and the flow A=B≃2C/5 (and permutations) results in the fastest dynamo with growth rate γ≃0.12 at the largest examined R(M). For the ABC flows that are driven at the second largest available length scale, it is found that (a) the 2 1/2-dimensional flows A=B,C=0 (and permutations) are again the first flows that result in a dynamo with a decreased onset. (b) The most symmetric flow, A=B=C, is the second type of flow that results in a dynamo. It is, and it remains, a local maximum. (c) At larger R(M), the flow A=B≃2C/5 (and permutations) appears as the third type of flow that results in a dynamo. As R(M) is increased, it becomes the flow with the largest growth rate. The growth rates appear to have some correlation with the Lyapunov exponents, but constructive refolding of the field lines appears equally important in determining the fastest dynamo flow.
Optimization of Regression Models of Experimental Data Using Confirmation Points

NASA Technical Reports Server (NTRS)

Ulbrich, N.

2010-01-01

A new search metric is discussed that may be used to better assess the predictive capability of different math term combinations during the optimization of a regression model of experimental data. The new search metric can be determined for each tested math term combination if the given experimental data set is split into two subsets. The first subset consists of data points that are only used to determine the coefficients of the regression model. The second subset consists of confirmation points that are exclusively used to test the regression model. The new search metric value is assigned after comparing two values that describe the quality of the fit of each subset. The first value is the standard deviation of the PRESS residuals of the data points. The second value is the standard deviation of the response residuals of the confirmation points. The greater of the two values is used as the new search metric value. This choice guarantees that both standard deviations are always less or equal to the value that is used during the optimization. Experimental data from the calibration of a wind tunnel strain-gage balance is used to illustrate the application of the new search metric. The new search metric ultimately generates an optimized regression model that was already tested at regression model independent confirmation points before it is ever used to predict an unknown response from a set of regressors.
A Targeted Search for Point Sources of EeV Neutrons

NASA Astrophysics Data System (ADS)

Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fernandes, M.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fox, B. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Fuji, T.; Gaior, R.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gate, F.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Hasankiadeh, Q. D.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Islo, K.; Jandt, I.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, A. J.; Matthews, J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morello, C.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Ochilo, L.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Papenbreer, P.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Peķala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Peters, C.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Privitera, P.; Prouza, M.; Purrello, V.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Taborda, O. A.; Tapia, A.; Tartare, M.; Thao, N. T.; Theodoro, V. M.; Tiffenberg, J.; Timmermans, C.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Vlcek, B.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Whelan, B. J.; Widom, A.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Auger Collaboration101, The Pierre

2014-07-01

A flux of neutrons from an astrophysical source in the Galaxy can be detected in the Pierre Auger Observatory as an excess of cosmic-ray air showers arriving from the direction of the source. To avoid the statistical penalty for making many trials, classes of objects are tested in combinations as nine "target sets," in addition to the search for a neutron flux from the Galactic center or from the Galactic plane. Within a target set, each candidate source is weighted in proportion to its electromagnetic flux, its exposure to the Auger Observatory, and its flux attenuation factor due to neutron decay. These searches do not find evidence for a neutron flux from any class of candidate sources. Tabulated results give the combined p-value for each class, with and without the weights, and also the flux upper limit for the most significant candidate source within each class. These limits on fluxes of neutrons significantly constrain models of EeV proton emission from non-transient discrete sources in the Galaxy.
Changing Perspective: Zooming in and out during Visual Search

ERIC Educational Resources Information Center

Solman, Grayden J. F.; Cheyne, J. Allan; Smilek, Daniel

2013-01-01

Laboratory studies of visual search are generally conducted in contexts with a static observer vantage point, constrained by a fixation cross or a headrest. In contrast, in many naturalistic search settings, observers freely adjust their vantage point by physically moving through space. In two experiments, we evaluate behavior during free vantage…
Preliminary Comparison of Three Search Engines for Point of Care Access to MEDLINE® Citations

PubMed Central

Hauser, Susan E.; Demner-Fushman, Dina; Ford, Glenn M.; Jacobs, Joshua L.; Thoma, George

2006-01-01

Medical resident physicians used MD on Tap in real time to search for MEDLINE citations relevant to clinical questions using three search engines: Essie, Entrez and Google™, in order of performance. PMID:17238564
Robust hashing with local models for approximate similarity search.

PubMed

Song, Jingkuan; Yang, Yi; Li, Xuelong; Huang, Zi; Yang, Yang

2014-07-01

Similarity search plays an important role in many applications involving high-dimensional data. Due to the known dimensionality curse, the performance of most existing indexing structures degrades quickly as the feature dimensionality increases. Hashing methods, such as locality sensitive hashing (LSH) and its variants, have been widely used to achieve fast approximate similarity search by trading search quality for efficiency. However, most existing hashing methods make use of randomized algorithms to generate hash codes without considering the specific structural information in the data. In this paper, we propose a novel hashing method, namely, robust hashing with local models (RHLM), which learns a set of robust hash functions to map the high-dimensional data points into binary hash codes by effectively utilizing local structural information. In RHLM, for each individual data point in the training dataset, a local hashing model is learned and used to predict the hash codes of its neighboring data points. The local models from all the data points are globally aligned so that an optimal hash code can be assigned to each data point. After obtaining the hash codes of all the training data points, we design a robust method by employing l2,1 -norm minimization on the loss function to learn effective hash functions, which are then used to map each database point into its hash code. Given a query data point, the search process first maps it into the query hash code by the hash functions and then explores the buckets, which have similar hash codes to the query hash code. Extensive experimental results conducted on real-life datasets show that the proposed RHLM outperforms the state-of-the-art methods in terms of search quality and efficiency.
Is searching full text more effective than searching abstracts?

PubMed Central

Lin, Jimmy

2009-01-01

Background With the growing availability of full-text articles online, scientists and other consumers of the life sciences literature now have the ability to go beyond searching bibliographic records (title, abstract, metadata) to directly access full-text content. Motivated by this emerging trend, I posed the following question: is searching full text more effective than searching abstracts? This question is answered by comparing text retrieval algorithms on MEDLINE® abstracts, full-text articles, and spans (paragraphs) within full-text articles using data from the TREC 2007 genomics track evaluation. Two retrieval models are examined: bm25 and the ranking algorithm implemented in the open-source Lucene search engine. Results Experiments show that treating an entire article as an indexing unit does not consistently yield higher effectiveness compared to abstract-only search. However, retrieval based on spans, or paragraphs-sized segments of full-text articles, consistently outperforms abstract-only search. Results suggest that highest overall effectiveness may be achieved by combining evidence from spans and full articles. Conclusion Users searching full text are more likely to find relevant articles than searching only abstracts. This finding affirms the value of full text collections for text retrieval and provides a starting point for future work in exploring algorithms that take advantage of rapidly-growing digital archives. Experimental results also highlight the need to develop distributed text retrieval algorithms, since full-text articles are significantly longer than abstracts and may require the computational resources of multiple machines in a cluster. The MapReduce programming model provides a convenient framework for organizing such computations. PMID:19192280
Waiting Points in Nova and X-ray Burst Nucleosynthesis

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

Sunayama, Tomomi; Smith, Michael Scott; Lingerfelt, Eric J

2008-01-01

In nova and X-ray burst nucleosynthesis, waiting points are nuclei in the reaction path which interrupt the nuclear flow towards heavier nuclei, typically because of a weak proton capture reaction and a long beta+ lifetime. Waiting points can influence the energy generation and final abundances synthesized in these explosions. We have constructed a systematic, quantitative set of criteria to identify rp-process waiting points, and use them to search for waiting points in post-processing simulations of novae and X-ray bursts. These criteria have been incorporated into the Computational Infrastructure for Nuclear Astrophysics, online at nucastrodata.org, to enable anyone to run customizedmore » searches for waiting points.« less
Waiting Points in Nova and X-ray burst Nucleosynthesis

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

Sunayama, Tomomi; Oak Ridge Institute for Science Education, Oak Ridge, Tennessee 37831-0117; Smith, Michael S.

2008-05-21

In nova and X-ray burst nucleosynthesis, waiting points are nuclei in the reaction path which delay the nuclear flow towards heavier nuclei, typically because of a weak proton capture reaction and a long {beta}{sup +} lifetime. Waiting points can influence the energy generation and final abundances synthesized in these explosions. We have constructed a systematic, quantitative set of criteria to identify rp-process waiting points, and use them to search for waiting points in post-processing simulations of novae and X-ray bursts. These criteria have been incorporated into the Computational Infrastructure for Nuclear Astrophysics, online at nucastrodata.org, to enable anyone to runmore » customized searches for waiting points.« less
Exploring Gendered Notions: Gender, Job Hunting and Web Searches

NASA Astrophysics Data System (ADS)

Martey, R. M.

Based on analysis of a series of interviews, this chapter suggests that in looking for jobs online, women confront gendered notions of the Internet as well as gendered notions of the jobs themselves. It argues that the social and cultural contexts of both the search tools and the search tasks should be considered in exploring how Web-based technologies serve women in a job search. For these women, the opportunities and limitations of online job-search tools were intimately related to their personal and social needs, especially needs for part-time work, maternity benefits, and career advancement. Although job-seeking services such as Monster.com were used frequently by most of these women, search services did not completely fulfill all their informational needs, and became an — often frustrating — initial starting point for a job search rather than an end-point.
Emplacement of the Santa Rita Flat pluton as a pluton-scale saddle reef

NASA Astrophysics Data System (ADS)

Vines, John A.; Law, Richard D.

2000-12-01

Regional mapping indicates that the Middle Jurassic Santa Rita Flat pluton, exposed in the Inyo Range of eastern California, is situated within the core of a south-plunging synform defined by bedding in the surrounding metasedimentary wall rocks, which dip beneath the pluton. However, bedding in rocks preserved above the pluton defines a south-plunging antiform. Anisotropy of magnetic susceptibility analysis revealed that magnetic foliation within the pluton also defines a south-plunging antiform, and the accompanying magnetic lineation plunges subparallel to the axis of this antiform. Our data indicate that the pluton was initially intruded as a sill in the hinge zone of the enveloping synform. Subsequent vertical inflation of the sill resulted in upward doming of the overlying roof and formation of the antiform now observed at the current erosion level in the pluton and preserved roof rocks. Emplacement of the pluton at 164 ± 1.5 Ma (U-Pb zircon age) overlaps in time with regional thrust faulting and folding ca. 185 148 Ma recognized in the southern Inyo Range. We speculate that space for initial emplacement of the pluton was produced during folding by layer-parallel slip and hinge-zone dilation, producing a saddle reef-like structure.
Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes

NASA Astrophysics Data System (ADS)

Wissman, J.; Finkenauer, L.; Deseri, L.; Majidi, C.

2014-10-01

We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K <0). Applying voltage Φ to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ϑ. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theory based on the principle of minimum potential energy to predict the principal curvatures as a function of Φ. Based on this theory, we predict a dependency of ϑ on Φ that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.
Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes

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

Wissman, J., E-mail: jwissman@andrew.cmu.edu; Finkenauer, L.; Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213

We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K<0). Applying voltage Φ to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ϑ. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theorymore » based on the principle of minimum potential energy to predict the principal curvatures as a function of Φ. Based on this theory, we predict a dependency of ϑ on Φ that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.« less
Critical points of the cosmic velocity field and the uncertainties in the value of the Hubble constant

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

Liu, Hao; Naselsky, Pavel; Mohayaee, Roya, E-mail: liuhao@nbi.dk, E-mail: roya@iap.fr, E-mail: naselsky@nbi.dk

2016-06-01

The existence of critical points for the peculiar velocity field is a natural feature of the correlated vector field. These points appear at the junctions of velocity domains with different orientations of their averaged velocity vectors. Since peculiar velocities are the important cause of the scatter in the Hubble expansion rate, we propose that a more precise determination of the Hubble constant can be made by restricting analysis to a subsample of observational data containing only the zones around the critical points of the peculiar velocity field, associated with voids and saddle points. On large-scales the critical points, where themore » first derivative of the gravitational potential vanishes, can easily be identified using the density field and classified by the behavior of the Hessian of the gravitational potential. We use high-resolution N-body simulations to show that these regions are stable in time and hence are excellent tracers of the initial conditions. Furthermore, we show that the variance of the Hubble flow can be substantially minimized by restricting observations to the subsample of such regions of vanishing velocity instead of aiming at increasing the statistics by averaging indiscriminately using the full data sets, as is the common approach.« less
Search for Point-like Sources of Ultra-high Energy Neutrinos at the Pierre Auger Observatory and Improved Limit on the Diffuse Flux of Tau Neutrinos

NASA Astrophysics Data System (ADS)

Pierre Auger Collaboration; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antiči'c, T.; Aramo, C.; Arganda, E.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellétoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Buroker, L.; Burton, R. E.; Caballero-Mora, K. S.; Caccianiga, B.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chirinos Diaz, J.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; del Río, M.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giller, M.; Gitto, J.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gouffon, P.; Grashorn, E.; Grebe, S.; Griffith, N.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Hollon, N.; Holmes, V. C.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jansen, S.; Jarne, C.; Jiraskova, S.; Josebachuili, M.; Kadija, K.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D.-H.; Kotera, K.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; LaHurd, D.; Latronico, L.; Lauer, R.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, J.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mazur, P. O.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Mertsch, P.; Meurer, C.; Meyhandan, R.; Mi'canovi'c, S.; Micheletti, M. I.; Minaya, I. A.; Miramonti, L.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Olinto, A.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Peķala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Ponce, V. H.; Pontz, M.; Porcelli, A.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez, G.; Rodriguez Cabo, I.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovánek, P.; Schröder, F.; Schulte, S.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Silva Lopez, H. H.; Sima, O.; 'Smiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanic, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Taşcău, O.; Tcaciuc, R.; Thao, N. T.; Thomas, D.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wommer, M.; Wundheiler, B.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano Garcia, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.

2012-08-01

The surface detector array of the Pierre Auger Observatory can detect neutrinos with energy E ν between 1017 eV and 1020 eV from point-like sources across the sky south of +55° and north of -65° declinations. A search has been performed for highly inclined extensive air showers produced by the interaction of neutrinos of all flavors in the atmosphere (downward-going neutrinos), and by the decay of tau leptons originating from tau neutrino interactions in Earth's crust (Earth-skimming neutrinos). No candidate neutrinos have been found in data up to 2010 May 31. This corresponds to an equivalent exposure of ~3.5 years of a full surface detector array for the Earth-skimming channel and ~2 years for the downward-going channel. An improved upper limit on the diffuse flux of tau neutrinos has been derived. Upper limits on the neutrino flux from point-like sources have been derived as a function of the source declination. Assuming a differential neutrino flux k PS · E -2 ν from a point-like source, 90% confidence level upper limits for k PS at the level of ≈5 × 10-7 and 2.5 × 10-6 GeV cm-2 s-1 have been obtained over a broad range of declinations from the searches for Earth-skimming and downward-going neutrinos, respectively.
Automated design of image operators that detect interest points.

PubMed

Trujillo, Leonardo; Olague, Gustavo

2008-01-01

This work describes how evolutionary computation can be used to synthesize low-level image operators that detect interesting points on digital images. Interest point detection is an essential part of many modern computer vision systems that solve tasks such as object recognition, stereo correspondence, and image indexing, to name but a few. The design of the specialized operators is posed as an optimization/search problem that is solved with genetic programming (GP), a strategy still mostly unexplored by the computer vision community. The proposed approach automatically synthesizes operators that are competitive with state-of-the-art designs, taking into account an operator's geometric stability and the global separability of detected points during fitness evaluation. The GP search space is defined using simple primitive operations that are commonly found in point detectors proposed by the vision community. The experiments described in this paper extend previous results (Trujillo and Olague, 2006a,b) by presenting 15 new operators that were synthesized through the GP-based search. Some of the synthesized operators can be regarded as improved manmade designs because they employ well-known image processing techniques and achieve highly competitive performance. On the other hand, since the GP search also generates what can be considered as unconventional operators for point detection, these results provide a new perspective to feature extraction research.
Resistivity Surveys on the Mauna Kea Saddle: Implications for groundwater resources on the Island of Hawaii

NASA Astrophysics Data System (ADS)

Thomas, D. M.; Pierce, H. A.

2009-12-01

A sequence of Audiomagnetotelluric (AMT) and Magnetotelluric (MT) surveys was recently completed on the Island of Hawaii along a transect spanning the 2000 m high Humu'ula Saddle region bounded by Mauna Kea, Mauna Loa and Hualalai volcanoes. The surveys extended down to an elevation of ~600 m on the eastern flank of the island and to 1,100 m on the drier, western slope of Mauna Kea and were intended to define the depth to the local groundwater table across the interior of the island. The results of the surveys present a much more complicated picture of the interior structure, and associated hydrology, of the island than has generally been assumed. At the eastern end of the transect, where existing wells unequivocally define the depth to the water table, young Mauna Kea basalts saturated with freshwater yielded a resistivity of ~600 ohm-meters. At increasing elevations toward the west, where rainfall rates decline markedly, the resistivity/depth profiles are consistent with progressively drier, resistive rocks to depths approaching 1000 m below the surface. These are underlain by well-defined, moderately resistive zones consistent with freshwater saturated basalts. As the transect approaches an inferred southeasterly-trending rift zone near the crest of the Saddle, the moderately resistive intervals are underlain by less resistive rocks near sea level that fall into the range expected for either (cold) saltwater or heated freshwater. Near the center of the transect, freshwater resistivity values extend to elevations of ~1000 m above sea level and are, again, underlain by significantly less resistive intervals near sea level. We believe that the moderately resistive intervals reflect substantial quantities of freshwater that are bounded by rift systems of Mauna Kea and Hualalai and the northern flank of Mauna Loa. The unexpectedly low resistivity values near sea level are considered to more probably reflect leakage of thermal fluids from the interior of Mauna Kea
Redesigning the DOE Data Explorer to embed dataset relationships at the point of search and to reflect landing page organization

DOE PAGES

Studwell, Sara; Robinson, Carly; Elliott, Jannean

2017-04-04

Scientific research is producing ever-increasing amounts of data. Organizing and reflecting relationships across data collections, datasets, publications, and other research objects are essential functionalities of the modern science environment, yet challenging to implement. Landing pages are often used for providing ‘big picture’ contextual frameworks for datasets and data collections, and many large-volume data holders are utilizing them in thoughtful, creative ways. The benefits of their organizational efforts, however, are not realized unless the user eventually sees the landing page at the end point of their search. What if that organization and ‘big picture’ context could benefit the user at themore » beginning of the search? That is a challenging approach, but The Department of Energy’s (DOE) Office of Scientific and Technical Information (OSTI) is redesigning the database functionality of the DOE Data Explorer (DDE) with that goal in mind. Phase I is focused on redesigning the DDE database to leverage relationships between two existing distinct populations in DDE, data Projects and individual Datasets, and then adding a third intermediate population, data Collections. Mapped, structured linkages, designed to show user relationships, will allow users to make informed search choices. These linkages will be sustainable and scalable, created automatically with the use of new metadata fields and existing authorities. Phase II will study selected DOE Data ID Service clients, analyzing how their landing pages are organized, and how that organization might be used to improve DDE search capabilities. At the heart of both phases is the realization that adding more metadata information for cross-referencing may require additional effort for data scientists. Finally, OSTI’s approach seeks to leverage existing metadata and landing page intelligence without imposing an additional burden on the data creators.« less
Redesigning the DOE Data Explorer to embed dataset relationships at the point of search and to reflect landing page organization

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

Studwell, Sara; Robinson, Carly; Elliott, Jannean

Scientific research is producing ever-increasing amounts of data. Organizing and reflecting relationships across data collections, datasets, publications, and other research objects are essential functionalities of the modern science environment, yet challenging to implement. Landing pages are often used for providing ‘big picture’ contextual frameworks for datasets and data collections, and many large-volume data holders are utilizing them in thoughtful, creative ways. The benefits of their organizational efforts, however, are not realized unless the user eventually sees the landing page at the end point of their search. What if that organization and ‘big picture’ context could benefit the user at themore » beginning of the search? That is a challenging approach, but The Department of Energy’s (DOE) Office of Scientific and Technical Information (OSTI) is redesigning the database functionality of the DOE Data Explorer (DDE) with that goal in mind. Phase I is focused on redesigning the DDE database to leverage relationships between two existing distinct populations in DDE, data Projects and individual Datasets, and then adding a third intermediate population, data Collections. Mapped, structured linkages, designed to show user relationships, will allow users to make informed search choices. These linkages will be sustainable and scalable, created automatically with the use of new metadata fields and existing authorities. Phase II will study selected DOE Data ID Service clients, analyzing how their landing pages are organized, and how that organization might be used to improve DDE search capabilities. At the heart of both phases is the realization that adding more metadata information for cross-referencing may require additional effort for data scientists. Finally, OSTI’s approach seeks to leverage existing metadata and landing page intelligence without imposing an additional burden on the data creators.« less

Temperature-driven evolution of critical points, interlayer coupling, and layer polarization in bilayer Mo S2

NASA Astrophysics Data System (ADS)

Du, Luojun; Zhang, Tingting; Liao, Mengzhou; Liu, Guibin; Wang, Shuopei; He, Rui; Ye, Zhipeng; Yu, Hua; Yang, Rong; Shi, Dongxia; Yao, Yugui; Zhang, Guangyu

2018-04-01

The recently emerging two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have been a fertile ground for exploring abundant exotic physical properties. Critical points, the extrema or saddle points of electronic bands, are the cornerstone of condensed-matter physics and fundamentally determine the optical and transport phenomena of the TMDCs. However, for bilayer Mo S2 , a typical TMDC and the unprecedented electrically tunable venue for valleytronics, there has been a considerable controversy on its intrinsic electronic structure, especially for the conduction band-edge locations. Moreover, interlayer hopping and layer polarization in bilayer Mo S2 which play vital roles in valley-spintronic applications have remained experimentally elusive. Here, we report the experimental observation of intrinsic critical points locations, interlayer hopping, layer-spin polarization, and their evolution with temperature in bilayer Mo S2 by performing temperature-dependent photoluminescence. Our measurements confirm that the conduction-band minimum locates at the Kc instead of Qc, and the energy splitting between Qc and Kc redshifts with a descent of temperature. Furthermore, the interlayer hopping energy for holes and temperature-dependent layer polarization are quantitatively determined. Our observations are in good harmony with density-functional theory calculations.
Chemical Information in Scirus and BASE (Bielefeld Academic Search Engine)

ERIC Educational Resources Information Center

Bendig, Regina B.

2009-01-01

The author sought to determine to what extent the two search engines, Scirus and BASE (Bielefeld Academic Search Engines), would be useful to first-year university students as the first point of searching for chemical information. Five topics were searched and the first ten records of each search result were evaluated with regard to the type of…
Myxosporea (Cnidaria : Myxozoa) infecting the saddled seabream Oblada melanura (L. 1758) (Teleostei : Sparidae) and the painted comber Serranus scriba (L. 1758) (Teleostei : Serranidae) in Tunisia.

PubMed

Laamiri, Sayef

2017-05-19

First parasitological surveys of Myxozoa are performed on the sparid saddled seabream Oblada melanura (Linnaeus, 1758) and the serranid painted comber Serranus scriba (Linnaeus, 1758) caught from the Bay of Bizerte and the Gulf of Tunis respectively in Northeast Tunisia, Western Mediterranean. In this study, 6 bivalvulid myxosporean species belonging to the 3 genera Ceratomyxa Thélohan, 1892, Myxodavisia Zhao, Zhou, Kent & Whipps, 2008 and Zschokkella Auerbach, 1910, are isolated infecting their hosts. Two species Ceratomyxa sp. 1 ex O. melanura (Prevalence (P) = 36%) and Ceratomyxa sp. 2 ex O. melanura (P = 13%) infected the saddled seabream and four species Ceratomyxa sp. 1 ex S. scriba (P = 11.7%), Ceratomyxa sp. 2 ex S. scriba (P = 6.7%), Myxodavisia sp. (P = 8.3%) and Zschokkella sp. (P = 5.6%) infected the painted comber. These myxosporeans differ, in vegetative stages and/or in mature spores, from all the previously known congeneric species, and are described here on the basis of their morphological and morphometric features, their host and tissue specificities and their biogeographical distribution. This is the first report of myxosporean infections in O. melanura and S. scriba. The occurrence of two ceratomyxid species in each host species supports that the genus Ceratomyxa is host-specific not only in sparids but also in serranids, which agrees with data previously obtained from Sparidae in Mediterranean Sea and from Serranidae in GBR, Australia. A member of the myxosporean genus Myxodavisia is recorded from the Mediterranean Sea for the first time, and Zschokkella spp. infections have not previously been recorded from a host in Serranidae. During the examination, a several cases of Co-infection among myxosporeans, both with two and three species, are provided and statistically studied. Indeed, 5% of the breams and 9.4% of the combers are infected with more than one myxosporean parasite. The relationship between myxosporean infections and some biological
Inferring Models of Bacterial Dynamics toward Point Sources

PubMed Central

Jashnsaz, Hossein; Nguyen, Tyler; Petrache, Horia I.; Pressé, Steve

2015-01-01

Experiments have shown that bacteria can be sensitive to small variations in chemoattractant (CA) concentrations. Motivated by these findings, our focus here is on a regime rarely studied in experiments: bacteria tracking point CA sources (such as food patches or even prey). In tracking point sources, the CA detected by bacteria may show very large spatiotemporal fluctuations which vary with distance from the source. We present a general statistical model to describe how bacteria locate point sources of food on the basis of stochastic event detection, rather than CA gradient information. We show how all model parameters can be directly inferred from single cell tracking data even in the limit of high detection noise. Once parameterized, our model recapitulates bacterial behavior around point sources such as the “volcano effect”. In addition, while the search by bacteria for point sources such as prey may appear random, our model identifies key statistical signatures of a targeted search for a point source given any arbitrary source configuration. PMID:26466373
Dynamic Harmony Search with Polynomial Mutation Algorithm for Valve-Point Economic Load Dispatch

PubMed Central

Karthikeyan, M.; Sree Ranga Raja, T.

2015-01-01

Economic load dispatch (ELD) problem is an important issue in the operation and control of modern control system. The ELD problem is complex and nonlinear with equality and inequality constraints which makes it hard to be efficiently solved. This paper presents a new modification of harmony search (HS) algorithm named as dynamic harmony search with polynomial mutation (DHSPM) algorithm to solve ORPD problem. In DHSPM algorithm the key parameters of HS algorithm like harmony memory considering rate (HMCR) and pitch adjusting rate (PAR) are changed dynamically and there is no need to predefine these parameters. Additionally polynomial mutation is inserted in the updating step of HS algorithm to favor exploration and exploitation of the search space. The DHSPM algorithm is tested with three power system cases consisting of 3, 13, and 40 thermal units. The computational results show that the DHSPM algorithm is more effective in finding better solutions than other computational intelligence based methods. PMID:26491710
Dynamic Harmony Search with Polynomial Mutation Algorithm for Valve-Point Economic Load Dispatch.

PubMed

Karthikeyan, M; Raja, T Sree Ranga

2015-01-01

Economic load dispatch (ELD) problem is an important issue in the operation and control of modern control system. The ELD problem is complex and nonlinear with equality and inequality constraints which makes it hard to be efficiently solved. This paper presents a new modification of harmony search (HS) algorithm named as dynamic harmony search with polynomial mutation (DHSPM) algorithm to solve ORPD problem. In DHSPM algorithm the key parameters of HS algorithm like harmony memory considering rate (HMCR) and pitch adjusting rate (PAR) are changed dynamically and there is no need to predefine these parameters. Additionally polynomial mutation is inserted in the updating step of HS algorithm to favor exploration and exploitation of the search space. The DHSPM algorithm is tested with three power system cases consisting of 3, 13, and 40 thermal units. The computational results show that the DHSPM algorithm is more effective in finding better solutions than other computational intelligence based methods.
The registration of non-cooperative moving targets laser point cloud in different view point

NASA Astrophysics Data System (ADS)

Wang, Shuai; Sun, Huayan; Guo, Huichao

2018-01-01

Non-cooperative moving target multi-view cloud registration is the key technology of 3D reconstruction of laser threedimension imaging. The main problem is that the density changes greatly and noise exists under different acquisition conditions of point cloud. In this paper, firstly, the feature descriptor is used to find the most similar point cloud, and then based on the registration algorithm of region segmentation, the geometric structure of the point is extracted by the geometric similarity between point and point, The point cloud is divided into regions based on spectral clustering, feature descriptors are created for each region, searching to find the most similar regions in the most similar point of view cloud, and then aligning the pair of point clouds by aligning their minimum bounding boxes. Repeat the above steps again until registration of all point clouds is completed. Experiments show that this method is insensitive to the density of point clouds and performs well on the noise of laser three-dimension imaging.
THE ROLE OF SEARCHING SERVICES IN AN ACQUISITIONS PROGRAM.

ERIC Educational Resources Information Center

LUECK, ANTOINETTE L.; AND OTHERS

A USER PRESENTS HIS POINT OF VIEW ON LITERATURE SEARCHING THROUGH THE MAJOR SEARCHING SERVICES IN THE OVERALL PROGRAM OF ACQUISITIONS FOR THE ENGINEERING STAFF OF THE AIR FORCE AERO PROPULSION LABORATORY. THESE MAJOR SEARCHING SERVICES INCLUDE THE DEFENSE DOCUMENTATION CENTER (DDC), THE NATIONAL AERONAUTICS AND SPACE ADMINISTRATION (NASA), THE…
Euclidean scalar field theory in the bilocal approximation

NASA Astrophysics Data System (ADS)

Nagy, S.; Polonyi, J.; Steib, I.

2018-04-01

The blocking step of the renormalization group method is usually carried out by restricting it to fluctuations and to local blocked action. The tree-level, bilocal saddle point contribution to the blocking, defined by the infinitesimal decrease of the sharp cutoff in momentum space, is followed within the three dimensional Euclidean ϕ6 model in this work. The phase structure is changed, new phases and relevant operators are found, and certain universality classes are restricted by the bilocal saddle point.
Higher rank ABJM Wilson loops from matrix models

DOE PAGES

Cookmeyer, Jonathan; Liu, James T.; Pando Zayas, Leopoldo A.

2016-11-21

We compute the vacuum expectation values of 1/6 supersymmetric Wilson loops in higher dimensional representations of the gauge group in ABJM theory. We then present results for the m-symmetric and m-antisymmetric representations by exploiting standard matrix model techniques. At leading order, in the saddle point approximation, our expressions reproduce holographic results from both D6 and D2 branes corresponding to the antisymmetric and symmetric representations, respectively. We also compute 1/N corrections to the leading saddle point results.
Moving Beyond Conventional Clinical Trial End Points in Treatment-refractory Metastatic Colorectal Cancer: A Composite Quality-of-life and Symptom Control End Point.

PubMed

Gong, Jun; Wu, Daniel; Chuang, Jeremy; Tuli, Richard; Simard, John; Hendifar, Andrew

2017-11-01

This review highlights the evidence supporting symptom control and quality-of-life (QOL) measures as predictors of survival in treatment-refractory metastatic colorectal cancer (mCRC) and describes a composite symptom control and QOL end point recently reported in a Phase III trial that may serve as a more reasonable end point of efficacy in this population. A literature search was conducted using MEDLINE to identify clinical studies (including case series and observational, retrospective, and prospective studies) that reported the predictive value of QOL measures for survival in mCRC. The search was limited by the following key words: quality of life, survival, and colorectal cancer. We then performed a second search limited to studies of randomized and Phase III design in mCRC to identify studies that used QOL assessments as their primary end points. A manual search was also performed to include additional studies of potential relevance. There is increasing evidence to support that symptom control and QOL measures are predictors of survival in treatment-refractory mCRC and can serve as an alternative but equally as important end point to survival in this population. A recent large, randomized Phase III trial using a composite primary end point of lean body mass, pain, anorexia, and fatigue reported the feasibility in evaluating benefit in mCRC beyond conventional clinical trial end points. Future studies in treatment-refractory mCRC may be better served by evaluating improvement in symptom control and QOL, which may otherwise serve as the best predictor of survival in last-line treatment settings. Copyright © 2017 Elsevier HS Journals, Inc. All rights reserved.
A hardware-oriented concurrent TZ search algorithm for High-Efficiency Video Coding

NASA Astrophysics Data System (ADS)

Doan, Nghia; Kim, Tae Sung; Rhee, Chae Eun; Lee, Hyuk-Jae

2017-12-01

High-Efficiency Video Coding (HEVC) is the latest video coding standard, in which the compression performance is double that of its predecessor, the H.264/AVC standard, while the video quality remains unchanged. In HEVC, the test zone (TZ) search algorithm is widely used for integer motion estimation because it effectively searches the good-quality motion vector with a relatively small amount of computation. However, the complex computation structure of the TZ search algorithm makes it difficult to implement it in the hardware. This paper proposes a new integer motion estimation algorithm which is designed for hardware execution by modifying the conventional TZ search to allow parallel motion estimations of all prediction unit (PU) partitions. The algorithm consists of the three phases of zonal, raster, and refinement searches. At the beginning of each phase, the algorithm obtains the search points required by the original TZ search for all PU partitions in a coding unit (CU). Then, all redundant search points are removed prior to the estimation of the motion costs, and the best search points are then selected for all PUs. Compared to the conventional TZ search algorithm, experimental results show that the proposed algorithm significantly decreases the Bjøntegaard Delta bitrate (BD-BR) by 0.84%, and it also reduces the computational complexity by 54.54%.
Adaptive Dynamic Programming for Discrete-Time Zero-Sum Games.

PubMed

Wei, Qinglai; Liu, Derong; Lin, Qiao; Song, Ruizhuo

2018-04-01

In this paper, a novel adaptive dynamic programming (ADP) algorithm, called "iterative zero-sum ADP algorithm," is developed to solve infinite-horizon discrete-time two-player zero-sum games of nonlinear systems. The present iterative zero-sum ADP algorithm permits arbitrary positive semidefinite functions to initialize the upper and lower iterations. A novel convergence analysis is developed to guarantee the upper and lower iterative value functions to converge to the upper and lower optimums, respectively. When the saddle-point equilibrium exists, it is emphasized that both the upper and lower iterative value functions are proved to converge to the optimal solution of the zero-sum game, where the existence criteria of the saddle-point equilibrium are not required. If the saddle-point equilibrium does not exist, the upper and lower optimal performance index functions are obtained, respectively, where the upper and lower performance index functions are proved to be not equivalent. Finally, simulation results and comparisons are shown to illustrate the performance of the present method.
Radially separated classical lumps in non-Abelian gauge models

NASA Astrophysics Data System (ADS)

Burzlaff, Jürgen

1985-04-01

We search for smooth and time-independent finite-energy solutions to Yang-Mills-Higgs theory with an arbitrary compact gauge group. Excluding the monopole solutions which have been studied before, we concentrate on configurations with no long-range fields, which include the saddle points corresponding to noncontractible (hyper-) loops. It is shown that if the radial dependence of the fields is factorized, only one solution satisfies all these conditions. This solution is the one which has been studied before by Dashen, Hasslacher, and Neveu and by Boguta, and whose existence has recently been proved rigorously. Formulas for the asymptotic behavior of this solution are given.
Visual search and attention: an overview.

PubMed

Davis, Elizabeth T; Palmer, John

2004-01-01

This special feature issue is devoted to attention and visual search. Attention is a central topic in psychology and visual search is both a versatile paradigm for the study of visual attention and a topic of study in itself. Visual search depends on sensory, perceptual, and cognitive processes. As a result, the search paradigm has been used to investigate a diverse range of phenomena. Manipulating the search task can vary the demands on attention. In turn, attention modulates visual search by selecting and limiting the information available at various levels of processing. Focusing on the intersection of attention and search provides a relatively structured window into the wide world of attentional phenomena. In particular, the effects of divided attention are illustrated by the effects of set size (the number of stimuli in a display) and the effects of selective attention are illustrated by cueing subsets of stimuli within the display. These two phenomena provide the starting point for the articles in this special issue. The articles are organized into four general topics to help structure the issues of attention and search.
Chemical-text hybrid search engines.

PubMed

Zhou, Yingyao; Zhou, Bin; Jiang, Shumei; King, Frederick J

2010-01-01

As the amount of chemical literature increases, it is critical that researchers be enabled to accurately locate documents related to a particular aspect of a given compound. Existing solutions, based on text and chemical search engines alone, suffer from the inclusion of "false negative" and "false positive" results, and cannot accommodate diverse repertoire of formats currently available for chemical documents. To address these concerns, we developed an approach called Entity-Canonical Keyword Indexing (ECKI), which converts a chemical entity embedded in a data source into its canonical keyword representation prior to being indexed by text search engines. We implemented ECKI using Microsoft Office SharePoint Server Search, and the resultant hybrid search engine not only supported complex mixed chemical and keyword queries but also was applied to both intranet and Internet environments. We envision that the adoption of ECKI will empower researchers to pose more complex search questions that were not readily attainable previously and to obtain answers at much improved speed and accuracy.
Executive Searches and the Use of Consultants

ERIC Educational Resources Information Center

Atwell, Robert H.

2009-01-01

Formerly, search consultants were used in higher education at only a small number of institutions--and even there, only when recruiting presidents. But over the years, the industry has grown to the point that many large and small firms now compete for higher education searches, including ones for administrators and even some for endowed faculty,…
Automated search method for AFM and profilers

NASA Astrophysics Data System (ADS)

Ray, Michael; Martin, Yves C.

2001-08-01

A new automation software creates a search model as an initial setup and searches for a user-defined target in atomic force microscopes or stylus profilometers used in semiconductor manufacturing. The need for such automation has become critical in manufacturing lines. The new method starts with a survey map of a small area of a chip obtained from a chip-design database or an image of the area. The user interface requires a user to point to and define a precise location to be measured, and to select a macro function for an application such as line width or contact hole. The search algorithm automatically constructs a range of possible scan sequences within the survey, and provides increased speed and functionality compared to the methods used in instruments to date. Each sequence consists in a starting point relative to the target, a scan direction, and a scan length. The search algorithm stops when the location of a target is found and criteria for certainty in positioning is met. With today's capability in high speed processing and signal control, the tool can simultaneously scan and search for a target in a robotic and continuous manner. Examples are given that illustrate the key concepts.
Adaptive rood pattern search for fast block-matching motion estimation.

PubMed

Nie, Yao; Ma, Kai-Kuang

2002-01-01

In this paper, we propose a novel and simple fast block-matching algorithm (BMA), called adaptive rood pattern search (ARPS), which consists of two sequential search stages: 1) initial search and 2) refined local search. For each macroblock (MB), the initial search is performed only once at the beginning in order to find a good starting point for the follow-up refined local search. By doing so, unnecessary intermediate search and the risk of being trapped into local minimum matching error points could be greatly reduced in long search case. For the initial search stage, an adaptive rood pattern (ARP) is proposed, and the ARP's size is dynamically determined for each MB, based on the available motion vectors (MVs) of the neighboring MBs. In the refined local search stage, a unit-size rood pattern (URP) is exploited repeatedly, and unrestrictedly, until the final MV is found. To further speed up the search, zero-motion prejudgment (ZMP) is incorporated in our method, which is particularly beneficial to those video sequences containing small motion contents. Extensive experiments conducted based on the MPEG-4 Verification Model (VM) encoding platform show that the search speed of our proposed ARPS-ZMP is about two to three times faster than that of the diamond search (DS), and our method even achieves higher peak signal-to-noise ratio (PSNR) particularly for those video sequences containing large and/or complex motion contents.
Phase-plane analysis to an “anisotropic” higher-order traffic flow model

NASA Astrophysics Data System (ADS)

Wu, Chun-Xiu

2018-04-01

The qualitative theory of differential equations is applied to investigate the traveling wave solution to an “anisotropic” higher-order viscous traffic flow model under the Lagrange coordinate system. The types and stabilities of the equilibrium points are discussed in the phase plane. Through the numerical simulation, the overall distribution structures of trajectories are drawn to analyze the relation between the phase diagram and the selected conservative solution variables, and the influences of the parameters on the system are studied. The limit-circle, limit circle-spiral point, saddle-spiral point and saddle-nodal point solutions are obtained. These steady-state solutions provide good explanation for the phenomena of the oscillatory and homogeneous congestions in real-world traffic.

Search without Boundaries Using Simple APIs

USGS Publications Warehouse

Tong, Qi

2009-01-01

The U.S. Geological Survey (USGS) Library, where the author serves as the digital services librarian, is increasingly challenged to make it easier for users to find information from many heterogeneous information sources. Information is scattered throughout different software applications (i.e., library catalog, federated search engine, link resolver, and vendor websites), and each specializes in one thing. How could the library integrate the functionalities of one application with another and provide a single point of entry for users to search across? To improve the user experience, the library launched an effort to integrate the federated search engine into the library's intranet website. The result is a simple search box that leverages the federated search engine's built-in application programming interfaces (APIs). In this article, the author describes how this project demonstrated the power of APIs and their potential to be used by other enterprise search portals inside or outside of the library.
Differential games.

NASA Technical Reports Server (NTRS)

Varaiya, P. P.

1972-01-01

General discussion of the theory of differential games with two players and zero sum. Games starting at a fixed initial state and ending at a fixed final time are analyzed. Strategies for the games are defined. The existence of saddle values and saddle points is considered. A stochastic version of a differential game is used to examine the synthesis problem.
A Class of Solvable Stopping Games

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

Alvarez, Luis H. R.

We consider a class of Dynkin games in the case where the underlying process evolves according to a one-dimensional but otherwise general diffusion. We establish general conditions under which both the value and the saddle point equilibrium exist and under which the exercise boundaries characterizing the saddle point strategy can be explicitly characterized in terms of a pair of standard first order necessary conditions for optimality. We also analyze those cases where an extremal pair of boundaries exists and investigate the overall impact of increased volatility on the equilibrium stopping strategies and their values.
Tunneling and reflection in unimolecular reaction kinetic energy release distributions

NASA Astrophysics Data System (ADS)

Hansen, K.

2018-02-01

The kinetic energy release distributions in unimolecular reactions is calculated with detailed balance theory, taking into account the tunneling and the reflection coefficient in three different types of transition states; (i) a saddle point corresponding to a standard RRKM-type theory, (ii) an attachment Langevin cross section, and (iii) an absorbing sphere potential at short range, without long range interactions. Corrections are significant in the one dimensional saddle point states. Very light and lightly bound absorbing systems will show measurable effects in decays from the absorbing sphere, whereas the Langevin cross section is essentially unchanged.
The Spiral of Life

NASA Astrophysics Data System (ADS)

Cajiao Vélez, F.; Kamiński, J. Z.; Krajewska, K.

2018-04-01

High-energy photoionization driven by short and circularly-polarized laser pulses is studied in the framework of the relativistic strong-field approximation. The saddle-point analysis of the integrals defining the probability amplitude is used to determine the general properties of the probability distributions. Additionally, an approximate solution to the saddle-point equation is derived. This leads to the concept of the three-dimensional spiral of life in momentum space, around which the ionization probability distribution is maximum. We demonstrate that such spiral is also obtained from a classical treatment.
Signatures of the electron saddle swaps mechanism in the photon spectra following charge-exchange collisions

NASA Astrophysics Data System (ADS)

Otranto, Sebastian

2014-10-01

During the last few years, several experimental and theoretical studies have focused on state selective charge exchange processes between charged ions and alkali metals. These data are of particular importance for the tokamak nuclear fusion reactor program, since diagnostics on the plasma usually rely on charge-exchange spectroscopy. In this sense, alkali metals, have been proposed as potential alternatives to excited hydrogen/deuterium for which laboratory experiments are not feasible at present. In this talk, we present our recent work involving ion collisions with alkali metals. Oscillatory structures in the angular differential charge-exchange cross sections obtained using the MOTRIMS technique are correctly described by classical trajectory Monte Carlo simulations. These oscillations are found to originate from the number of swaps the electron undergoes around the projectile-target potential saddle before capture takes place and are very prominent at impact energies below 10 keV/amu. Moreover, cross sections of higher order of differentiability also indicate that the swaps leave distinctive signatures in the (n,l)-state selective cross sections and in the photon line emission cross sections. Oscillatory structures for the x-ray hardness ratio parameter are also predicted. In collaboration with Ronnie Hoekstra, Zernike Institute for Advanced Materials, University of Groningen and Ronald Olson, Department of Physics, Missouri University of Science and Technology.
Stride search: A general algorithm for storm detection in high resolution climate data

DOE PAGES

Bosler, Peter Andrew; Roesler, Erika Louise; Taylor, Mark A.; ...

2015-09-08

This article discusses the problem of identifying extreme climate events such as intense storms within large climate data sets. The basic storm detection algorithm is reviewed, which splits the problem into two parts: a spatial search followed by a temporal correlation problem. Two specific implementations of the spatial search algorithm are compared. The commonly used grid point search algorithm is reviewed, and a new algorithm called Stride Search is introduced. Stride Search is designed to work at all latitudes, while grid point searches may fail in polar regions. Results from the two algorithms are compared for the application of tropicalmore » cyclone detection, and shown to produce similar results for the same set of storm identification criteria. The time required for both algorithms to search the same data set is compared. Furthermore, Stride Search's ability to search extreme latitudes is demonstrated for the case of polar low detection.« less
Local weather is associated with rates of online searches for musculoskeletal pain symptoms.

PubMed

Telfer, Scott; Obradovich, Nick

2017-01-01

Weather conditions are commonly believed to influence musculoskeletal pain, however the evidence for this is mixed. This study aimed to examine the relationship between local meteorological conditions and online search trends for terms related to knee pain, hip pain, and arthritis. Five years of relative online search volumes for these terms were obtained for the 50 most populous cities in the contiguous United States, along with corresponding local weather data for temperature, relative humidity, barometric pressure, and precipitation. Methods from the climate econometrics literature were used to assess the casual impact of these meteorological variables on the relative volumes of searches for pain. For temperatures between -5°C and 30°C, search volumes for hip pain increased by 12 index points, and knee pain increased by 18 index points. Precipitation had a negative effect on search volumes for these terms. At temperatures >30°C, search volumes for arthritis related pain decreased by 7 index points. These patterns were not seen for pain searches unrelated to the musculoskeletal system. In summary, selected local weather conditions are significantly associated with online search volumes for specific musculoskeletal pain symptoms. We believe the predominate driver for this to be the relative changes in physical activity levels associated with meteorological conditions.
Bottlenecks and Waiting Points in Nucleosynthesis in X-ray bursts and Novae

NASA Astrophysics Data System (ADS)

Smith, Michael S.; Sunayama, Tomomi; Hix, W. Raphael; Lingerfelt, Eric J.; Nesaraja, Caroline D.

2010-08-01

To better understand the energy generation and element synthesis occurring in novae and X-ray bursts, we give quantitative definitions to the concepts of ``bottlenecks'' and ``waiting points'' in the thermonuclear reaction flow. We use these criteria to search for bottlenecks and waiting points in post-processing element synthesis explosion simulations. We have incorporated these into the Computational Infrastructure for Nuclear Astrophysics, a suite of nuclear astrophysics codes available online at nucastrodata.org, so that anyone may perform custom searches for bottlenecks and waiting points.
Bottlenecks and Waiting Points in Nucleosynthesis in X-ray bursts and Novae

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

Smith, Michael S.; Hix, W. Raphael; Nesaraja, Caroline D.

2010-08-12

To better understand the energy generation and element synthesis occurring in novae and X-ray bursts, we give quantitative definitions to the concepts of ''bottlenecks'' and ''waiting points'' in the thermonuclear reaction flow. We use these criteria to search for bottlenecks and waiting points in post-processing element synthesis explosion simulations. We have incorporated these into the Computational Infrastructure for Nuclear Astrophysics, a suite of nuclear astrophysics codes available online at nucastrodata.org, so that anyone may perform custom searches for bottlenecks and waiting points.
An intermittent control model of flexible human gait using a stable manifold of saddle-type unstable limit cycle dynamics

PubMed Central

Fu, Chunjiang; Suzuki, Yasuyuki; Kiyono, Ken; Morasso, Pietro; Nomura, Taishin

2014-01-01

Stability of human gait is the ability to maintain upright posture during walking against external perturbations. It is a complex process determined by a number of cross-related factors, including gait trajectory, joint impedance and neural control strategies. Here, we consider a control strategy that can achieve stable steady-state periodic gait while maintaining joint flexibility with the lowest possible joint impedance. To this end, we carried out a simulation study of a heel-toe footed biped model with hip, knee and ankle joints and a heavy head-arms-trunk element, working in the sagittal plane. For simplicity, the model assumes a periodic desired joint angle trajectory and joint torques generated by a set of feed-forward and proportional-derivative feedback controllers, whereby the joint impedance is parametrized by the feedback gains. We could show that a desired steady-state gait accompanied by the desired joint angle trajectory can be established as a stable limit cycle (LC) for the feedback controller with an appropriate set of large feedback gains. Moreover, as the feedback gains are decreased for lowering the joint stiffness, stability of the LC is lost only in a few dimensions, while leaving the remaining large number of dimensions quite stable: this means that the LC becomes saddle-type, with a low-dimensional unstable manifold and a high-dimensional stable manifold. Remarkably, the unstable manifold remains of low dimensionality even when the feedback gains are decreased far below the instability point. We then developed an intermittent neural feedback controller that is activated only for short periods of time at an optimal phase of each gait stride. We characterized the robustness of this design by showing that it can better stabilize the unstable LC with small feedback gains, leading to a flexible gait, and in particular we demonstrated that such an intermittent controller performs better if it drives the state point to the stable manifold, rather
An intermittent control model of flexible human gait using a stable manifold of saddle-type unstable limit cycle dynamics.

PubMed

Fu, Chunjiang; Suzuki, Yasuyuki; Kiyono, Ken; Morasso, Pietro; Nomura, Taishin

2014-12-06

Stability of human gait is the ability to maintain upright posture during walking against external perturbations. It is a complex process determined by a number of cross-related factors, including gait trajectory, joint impedance and neural control strategies. Here, we consider a control strategy that can achieve stable steady-state periodic gait while maintaining joint flexibility with the lowest possible joint impedance. To this end, we carried out a simulation study of a heel-toe footed biped model with hip, knee and ankle joints and a heavy head-arms-trunk element, working in the sagittal plane. For simplicity, the model assumes a periodic desired joint angle trajectory and joint torques generated by a set of feed-forward and proportional-derivative feedback controllers, whereby the joint impedance is parametrized by the feedback gains. We could show that a desired steady-state gait accompanied by the desired joint angle trajectory can be established as a stable limit cycle (LC) for the feedback controller with an appropriate set of large feedback gains. Moreover, as the feedback gains are decreased for lowering the joint stiffness, stability of the LC is lost only in a few dimensions, while leaving the remaining large number of dimensions quite stable: this means that the LC becomes saddle-type, with a low-dimensional unstable manifold and a high-dimensional stable manifold. Remarkably, the unstable manifold remains of low dimensionality even when the feedback gains are decreased far below the instability point. We then developed an intermittent neural feedback controller that is activated only for short periods of time at an optimal phase of each gait stride. We characterized the robustness of this design by showing that it can better stabilize the unstable LC with small feedback gains, leading to a flexible gait, and in particular we demonstrated that such an intermittent controller performs better if it drives the state point to the stable manifold, rather
Development of cryogenic CMOS Readout ASICs for the Point-Contact HPGe Detectors for Dark Matter Search and Neutrino Experiments

NASA Astrophysics Data System (ADS)

Deng, Zhi; He, Li; Liu, Feng; Liu, Yinong; Xue, Tao; Li, Yulan; Yue, Qian

2017-05-01

The paper presents the developments of two cryogenic readout ASICs for the point-contact HPGe detectors for dark matter search and neutrino experiments. Extremely low noise readout electronics were demanded and the capability of working at cryogenic temperatures may bring great advantages. The first ASIC was a monolithic CMOS charge sensitive preamplifier with its noise optimized for ∼1 pF input capacitance. The second ASIC was a waveform recorder based on switched capacitor array. These two ASICs were fabricated in CMOS 350 nm and 180 nm processes respectively. The prototype chips were tested and showed promising results. Both ASICs worked well at low temperature. The preamplifier had achieved ENC of 10.3 electrons with 0.7 pF input capacitance and the SCA chip could run at 9 bit effective resolution and 25 MSPS sampling rate.
Point Set Denoising Using Bootstrap-Based Radial Basis Function.

PubMed

Liew, Khang Jie; Ramli, Ahmad; Abd Majid, Ahmad

2016-01-01

This paper examines the application of a bootstrap test error estimation of radial basis functions, specifically thin-plate spline fitting, in surface smoothing. The presence of noisy data is a common issue of the point set model that is generated from 3D scanning devices, and hence, point set denoising is one of the main concerns in point set modelling. Bootstrap test error estimation, which is applied when searching for the smoothing parameters of radial basis functions, is revisited. The main contribution of this paper is a smoothing algorithm that relies on a bootstrap-based radial basis function. The proposed method incorporates a k-nearest neighbour search and then projects the point set to the approximated thin-plate spline surface. Therefore, the denoising process is achieved, and the features are well preserved. A comparison of the proposed method with other smoothing methods is also carried out in this study.
Representational Flexibility and Response Control in a Multistep Multilocation Search Task.

ERIC Educational Resources Information Center

Zelazo, Philip David; Reznick, J. Steven; Spinazzola, Joseph

1998-01-01

Three experiments explored determinants of two-year olds' perseverative errors in a search task. Found that active search, even in the absence of observation, produced perseveration on post-switch trails, but mere observation did not. Results indicated that active search is required to elicit perseveration, which points to failures of response…
A Hybrid Symbiotic Organisms Search Algorithm with Variable Neighbourhood Search for Solving Symmetric and Asymmetric Traveling Salesman Problem

NASA Astrophysics Data System (ADS)

Umam, M. I. H.; Santosa, B.

2018-04-01

Combinatorial optimization has been frequently used to solve both problems in science, engineering, and commercial applications. One combinatorial problems in the field of transportation is to find a shortest travel route that can be taken from the initial point of departure to point of destination, as well as minimizing travel costs and travel time. When the distance from one (initial) node to another (destination) node is the same with the distance to travel back from destination to initial, this problems known to the Traveling Salesman Problem (TSP), otherwise it call as an Asymmetric Traveling Salesman Problem (ATSP). The most recent optimization techniques is Symbiotic Organisms Search (SOS). This paper discuss how to hybrid the SOS algorithm with variable neighborhoods search (SOS-VNS) that can be applied to solve the ATSP problem. The proposed mechanism to add the variable neighborhoods search as a local search is to generate the better initial solution and then we modify the phase of parasites with adapting mechanism of mutation. After modification, the performance of the algorithm SOS-VNS is evaluated with several data sets and then the results is compared with the best known solution and some algorithm such PSO algorithm and SOS original algorithm. The SOS-VNS algorithm shows better results based on convergence, divergence and computing time.
Development of POINTS as a planetology instrument

NASA Technical Reports Server (NTRS)

Reasenberg, Robert D.

1994-01-01

During the reporting period, we carried out investigations required to enhance our design of POINTS as a tool for the search for and characterization of extra-solar planetary systems. The results of that work were included in a paper on POINTS as well as one on Newcomb, which will soon appear in the proceedings of SPIE Conference 2200. (Newcomb is a spinoff of POINTS. It is a small astrometric interferometer now being developed jointly by SAO and the U.S. Navy. It could help establish some of the technology needed for POINTS.) These papers are appended.
An Iterative Closest Points Algorithm for Registration of 3D Laser Scanner Point Clouds with Geometric Features.

PubMed

He, Ying; Liang, Bin; Yang, Jun; Li, Shunzhi; He, Jin

2017-08-11

The Iterative Closest Points (ICP) algorithm is the mainstream algorithm used in the process of accurate registration of 3D point cloud data. The algorithm requires a proper initial value and the approximate registration of two point clouds to prevent the algorithm from falling into local extremes, but in the actual point cloud matching process, it is difficult to ensure compliance with this requirement. In this paper, we proposed the ICP algorithm based on point cloud features (GF-ICP). This method uses the geometrical features of the point cloud to be registered, such as curvature, surface normal and point cloud density, to search for the correspondence relationships between two point clouds and introduces the geometric features into the error function to realize the accurate registration of two point clouds. The experimental results showed that the algorithm can improve the convergence speed and the interval of convergence without setting a proper initial value.
An Iterative Closest Points Algorithm for Registration of 3D Laser Scanner Point Clouds with Geometric Features

PubMed Central

Liang, Bin; Yang, Jun; Li, Shunzhi; He, Jin

2017-01-01

The Iterative Closest Points (ICP) algorithm is the mainstream algorithm used in the process of accurate registration of 3D point cloud data. The algorithm requires a proper initial value and the approximate registration of two point clouds to prevent the algorithm from falling into local extremes, but in the actual point cloud matching process, it is difficult to ensure compliance with this requirement. In this paper, we proposed the ICP algorithm based on point cloud features (GF-ICP). This method uses the geometrical features of the point cloud to be registered, such as curvature, surface normal and point cloud density, to search for the correspondence relationships between two point clouds and introduces the geometric features into the error function to realize the accurate registration of two point clouds. The experimental results showed that the algorithm can improve the convergence speed and the interval of convergence without setting a proper initial value. PMID:28800096
Efficient protein structure search using indexing methods

PubMed Central

2013-01-01

Understanding functions of proteins is one of the most important challenges in many studies of biological processes. The function of a protein can be predicted by analyzing the functions of structurally similar proteins, thus finding structurally similar proteins accurately and efficiently from a large set of proteins is crucial. A protein structure can be represented as a vector by 3D-Zernike Descriptor (3DZD) which compactly represents the surface shape of the protein tertiary structure. This simplified representation accelerates the searching process. However, computing the similarity of two protein structures is still computationally expensive, thus it is hard to efficiently process many simultaneous requests of structurally similar protein search. This paper proposes indexing techniques which substantially reduce the search time to find structurally similar proteins. In particular, we first exploit two indexing techniques, i.e., iDistance and iKernel, on the 3DZDs. After that, we extend the techniques to further improve the search speed for protein structures. The extended indexing techniques build and utilize an reduced index constructed from the first few attributes of 3DZDs of protein structures. To retrieve top-k similar structures, top-10 × k similar structures are first found using the reduced index, and top-k structures are selected among them. We also modify the indexing techniques to support θ-based nearest neighbor search, which returns data points less than θ to the query point. The results show that both iDistance and iKernel significantly enhance the searching speed. In top-k nearest neighbor search, the searching time is reduced 69.6%, 77%, 77.4% and 87.9%, respectively using iDistance, iKernel, the extended iDistance, and the extended iKernel. In θ-based nearest neighbor serach, the searching time is reduced 80%, 81%, 95.6% and 95.6% using iDistance, iKernel, the extended iDistance, and the extended iKernel, respectively. PMID:23691543

Efficient protein structure search using indexing methods.

PubMed

Kim, Sungchul; Sael, Lee; Yu, Hwanjo

2013-01-01

Understanding functions of proteins is one of the most important challenges in many studies of biological processes. The function of a protein can be predicted by analyzing the functions of structurally similar proteins, thus finding structurally similar proteins accurately and efficiently from a large set of proteins is crucial. A protein structure can be represented as a vector by 3D-Zernike Descriptor (3DZD) which compactly represents the surface shape of the protein tertiary structure. This simplified representation accelerates the searching process. However, computing the similarity of two protein structures is still computationally expensive, thus it is hard to efficiently process many simultaneous requests of structurally similar protein search. This paper proposes indexing techniques which substantially reduce the search time to find structurally similar proteins. In particular, we first exploit two indexing techniques, i.e., iDistance and iKernel, on the 3DZDs. After that, we extend the techniques to further improve the search speed for protein structures. The extended indexing techniques build and utilize an reduced index constructed from the first few attributes of 3DZDs of protein structures. To retrieve top-k similar structures, top-10 × k similar structures are first found using the reduced index, and top-k structures are selected among them. We also modify the indexing techniques to support θ-based nearest neighbor search, which returns data points less than θ to the query point. The results show that both iDistance and iKernel significantly enhance the searching speed. In top-k nearest neighbor search, the searching time is reduced 69.6%, 77%, 77.4% and 87.9%, respectively using iDistance, iKernel, the extended iDistance, and the extended iKernel. In θ-based nearest neighbor serach, the searching time is reduced 80%, 81%, 95.6% and 95.6% using iDistance, iKernel, the extended iDistance, and the extended iKernel, respectively.
Multi-scaling in the critical phenomena in the quenched disordered systems

NASA Astrophysics Data System (ADS)

Wu, X. T.

2018-04-01

The Landau-Ginzburg-Wilson Hamiltonian with random temperature for the phase transition in disordered systems from the Griffiths phase to ordered phase is reexamined. From the saddle point solutions, especially the excited state solutions, it is shown that the system self-organizes into blocks coupled with their neighbors like superspins, which are emergent variables. Taking the fluctuation around these saddle point solutions into account, we get an effective Hamiltonian, including the emergent superspins of the blocks, the fluctuation around the saddle point solutions, and their couplings. Applying Stratonovich-Hubbard transformation to the part of superspins, we get a Landau-Ginzburg-Wilson Hamiltonian for the blocks. From the saddle point equations for the blocks, we can get the second generation blocks, of which sizes are much larger than the first generation blocks. Repeating this procedure again and again, we get many generations of blocks to describe the asymptotic behavior. If a field is applied, the effective field on the superspins is multiplied greatly and proportional to the block size. For a very small field, the effective field on the higher generation superspins can be so strong to cause the superspins polarized radically. This can explain the extra large critical isotherm exponent discovered in the experiments. The phase space of reduced temperature vs. field is divided into many layers , in which different generation blocks dominate the critical behavior. The sizes of the different generation emergent blocks are new relevant length scales. This can explain a lot of puzzles in the experiments and the Monte Carlo simulation.
Decentralized Bayesian search using approximate dynamic programming methods.

PubMed

Zhao, Yijia; Patek, Stephen D; Beling, Peter A

2008-08-01

We consider decentralized Bayesian search problems that involve a team of multiple autonomous agents searching for targets on a network of search points operating under the following constraints: 1) interagent communication is limited; 2) the agents do not have the opportunity to agree in advance on how to resolve equivalent but incompatible strategies; and 3) each agent lacks the ability to control or predict with certainty the actions of the other agents. We formulate the multiagent search-path-planning problem as a decentralized optimal control problem and introduce approximate dynamic heuristics that can be implemented in a decentralized fashion. After establishing some analytical properties of the heuristics, we present computational results for a search problem involving two agents on a 5 x 5 grid.
Saddle-nose and bilateral cauliflower ear deformities with pyoderma gangrenosum-like ulcers, cavitary pulmonary lesions, digital gangrene and pulselessness in a young female.

PubMed

Subhadarshani, Sweta; Gupta, Vishal; Chahal, Anurag; Verma, Kaushal K

2017-06-15

We report a young female who presented with saddle-nose and bilateral cauliflower ear deformities along with pyoderma gangrenosum-like ulcers, digital gangrene and pulselessness. Subsequently, she was found to have bilateral conductive hearing loss, a corneal opacity, mild aortic regurgitation and radiological evidence of cavitary changes in lungs and aortoarteritis. Our patient had a constellation of symptoms which posed a diagnostic challenge. Finally, a diagnosis of relapsing polychondritis with several unusual features was made. Overlap with Takayasu's arteritis and granulomatosis with polyangitis, which has been reported rarely in the literature, cannot be excluded. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
A search for outflows from X-ray bright points in coronal holes

NASA Technical Reports Server (NTRS)

Mullan, D. J.; Waldron, W. L.

1986-01-01

Properties of X-ray bright points using two of the instruments on Solar Maximum Mission were investigated. The mass outflows from magnetic regions were modeled using a two dimensional MHD code. It was concluded that mass can be detected from X-ray bright points provided that the magnetic topology is favorable.
Nursing Reference Center: a point-of-care resource.

PubMed

Vardell, Emily; Paulaitis, Gediminas Geddy

2012-01-01

Nursing Reference Center is a point-of-care resource designed for the practicing nurse, as well as nursing administrators, nursing faculty, and librarians. Users can search across multiple resources, including topical Quick Lessons, evidence-based care sheets, patient education materials, practice guidelines, and more. Additional features include continuing education modules, e-books, and a new iPhone application. A sample search and comparison with similar databases were conducted.
The "Make or Buy" Decision: Five Main Points to Consider

ERIC Educational Resources Information Center

Archer, Mary Ann E.

1978-01-01

Five points which should be considered when making decisions about whether to purchase magnetic tapes for in-hours searching by batch processing, purchase terminals and contract with on-line vendors, or contract with information brokers for retrospective searching or SDI are availability of information in the most useful form, hardware and…
Psychological and social factors affecting Internet searches on suicide in Korea: a big data analysis of Google search trends.

PubMed

Song, Tae Min; Song, Juyoung; An, Ji-Young; Hayman, Laura L; Woo, Jong-Min

2014-01-01

The average mortality rate for death by suicide among OECD countries is 12.8 per 100000, and 33.5 for Korea. The present study analyzed big data extracted from Google to identify factors related to searches on suicide in Korea. Google search trends for the search words of suicide, stress, exercise, and drinking were obtained for 2004-2010. Analyzing data by month, the relationship between the actual number of suicides and search words per year was examined using multi-level models. Both suicide rates and Google searches on suicide in Korea increased since 2007. An unconditional slope model indicated stress and suicide-related searches were positively related. A conditional model showed that factors associated with suicide by year directly affected suicide-related searches. The interaction between stress-related searches and the actual number of suicides was significant. A positive relationship between stress- and suicide-related searches further confirmed that stress affects suicide. Taken together and viewed in context of the big data analysis, our results point to the need for a tailored prevention program. Real-time big data can be of use in indicating increases in suicidality when search words such as stress and suicide generate greater numbers of hits on portals and social network sites.
Psychological and Social Factors Affecting Internet Searches on Suicide in Korea: A Big Data Analysis of Google Search Trends

PubMed Central

Song, Tae Min; Song, Juyoung; Hayman, Laura L.; Woo, Jong-Min

2014-01-01

Purpose The average mortality rate for death by suicide among OECD countries is 12.8 per 100000, and 33.5 for Korea. The present study analyzed big data extracted from Google to identify factors related to searches on suicide in Korea. Materials and Methods Google search trends for the search words of suicide, stress, exercise, and drinking were obtained for 2004-2010. Analyzing data by month, the relationship between the actual number of suicides and search words per year was examined using multi-level models. Results Both suicide rates and Google searches on suicide in Korea increased since 2007. An unconditional slope model indicated stress and suicide-related searches were positively related. A conditional model showed that factors associated with suicide by year directly affected suicide-related searches. The interaction between stress-related searches and the actual number of suicides was significant. Conclusion A positive relationship between stress- and suicide-related searches further confirmed that stress affects suicide. Taken together and viewed in context of the big data analysis, our results point to the need for a tailored prevention program. Real-time big data can be of use in indicating increases in suicidality when search words such as stress and suicide generate greater numbers of hits on portals and social network sites. PMID:24339315
Stride search: A general algorithm for storm detection in high-resolution climate data

DOE PAGES

Bosler, Peter A.; Roesler, Erika L.; Taylor, Mark A.; ...

2016-04-13

This study discusses the problem of identifying extreme climate events such as intense storms within large climate data sets. The basic storm detection algorithm is reviewed, which splits the problem into two parts: a spatial search followed by a temporal correlation problem. Two specific implementations of the spatial search algorithm are compared: the commonly used grid point search algorithm is reviewed, and a new algorithm called Stride Search is introduced. The Stride Search algorithm is defined independently of the spatial discretization associated with a particular data set. Results from the two algorithms are compared for the application of tropical cyclonemore » detection, and shown to produce similar results for the same set of storm identification criteria. Differences between the two algorithms arise for some storms due to their different definition of search regions in physical space. The physical space associated with each Stride Search region is constant, regardless of data resolution or latitude, and Stride Search is therefore capable of searching all regions of the globe in the same manner. Stride Search's ability to search high latitudes is demonstrated for the case of polar low detection. Wall clock time required for Stride Search is shown to be smaller than a grid point search of the same data, and the relative speed up associated with Stride Search increases as resolution increases.« less
[Eye movement study in multiple object search process].

PubMed

Xu, Zhaofang; Liu, Zhongqi; Wang, Xingwei; Zhang, Xin

2017-04-01

The aim of this study is to investigate the search time regulation of objectives and eye movement behavior characteristics in the multi-objective visual search. The experimental task was accomplished with computer programming and presented characters on a 24 inch computer display. The subjects were asked to search three targets among the characters. Three target characters in the same group were of high similarity degree while those in different groups of target characters and distraction characters were in different similarity degrees. We recorded the search time and eye movement data through the whole experiment. It could be seen from the eye movement data that the quantity of fixation points was large when the target characters and distraction characters were similar. There were three kinds of visual search patterns for the subjects including parallel search, serial search, and parallel-serial search. In addition, the last pattern had the best search performance among the three search patterns, that is, the subjects who used parallel-serial search pattern spent shorter time finding the target. The order that the targets presented were able to affect the search performance significantly; and the similarity degree between target characters and distraction characters could also affect the search performance.
Time-Dependent Searches for Point Sources of Neutrinos with the 40-String and 22-String Configurations of IceCube

NASA Technical Reports Server (NTRS)

Stamatikos, M.

2012-01-01

This paper presents four searches for flaring sources of neutrinos using the IceCube neutrino telescope. For the first time, a search is performed over the entire parameter space of energy, direction and time with sensitivity to neutrino flares lasting between 20 microseconds and a year duration from astrophysical sources. Searches which integrate over time are less sensitive to flares because they are affected by a larger background of atmospheric neutrinos and muons that can be reduced by the use of additional timing information. Flaring sources considered here, such as active galactic nuclei, soft gamma ray repeaters and gamma-ray bursts, are promising candidate neutrino emitters. Two searches are untriggered in the sense that they look for any possible flare in the entire sky and from a predefined catalog of sources from which photon flares have been recorded. The other two searches are triggered by multi-wavelength information on flares from blazars and from a soft gamma-ray repeater. One triggered search uses lightcurves from Fermi-LAT which provides continuous monitoring. A second triggered search uses information where the flux states have been measured only for short periods of time near the flares. The untriggered searches use data taken by 40 strings of IceCube between Apr 5, 2008 and May 20, 2009. The triggered searches also use data taken by the 22-string configuration of IceCube operating between May 31, 2007 and Apr 5, 2008. The results from all four searches are compatible with a fluctuation of the background.
Time-dependent Searches for Point Sources of Neutrinos with the 40-string and 22-string Configurations of IceCube

NASA Astrophysics Data System (ADS)

Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brown, A. M.; Buitink, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; De Clercq, C.; Demirörs, L.; Denger, T.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; DeYoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Heinen, D.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lünemann, J.; Madsen, J.; Majumdar, P.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Ono, M.; Panknin, S.; Paul, L.; Pérez de los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schmidt, T.; Schönwald, A.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stössl, A.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Stür, M.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; Van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; IceCube Collaboration

2012-01-01

This paper presents four searches for flaring sources of neutrinos using the IceCube neutrino telescope. For the first time, a search is performed over the entire parameter space of energy, direction, and time with sensitivity to neutrino flares lasting between 20 μs and a year duration from astrophysical sources. Searches that integrate over time are less sensitive to flares because they are affected by a larger background of atmospheric neutrinos and muons that can be reduced by the use of additional timing information. Flaring sources considered here, such as active galactic nuclei, soft gamma-ray repeaters, and gamma-ray bursts, are promising candidate neutrino emitters. Two searches are "untriggered" in the sense that they look for any possible flare in the entire sky and from a predefined catalog of sources from which photon flares have been recorded. The other two searches are triggered by multi-wavelength information on flares from blazars and from a soft gamma-ray repeater. One triggered search uses lightcurves from Fermi-LAT which provides continuous monitoring. A second triggered search uses information where the flux states have been measured only for short periods of time near the flares. The untriggered searches use data taken by 40 strings of IceCube between 2008 April 5 and 2009 May 20. The triggered searches also use data taken by the 22-string configuration of IceCube operating between 2007 May 31 and 2008 April 5. The results from all four searches are compatible with a fluctuation of the background.
Automatic Registration of Terrestrial Laser Scanner Point Clouds Using Natural Planar Surfaces

NASA Astrophysics Data System (ADS)

Theiler, P. W.; Schindler, K.

2012-07-01

Terrestrial laser scanners have become a standard piece of surveying equipment, used in diverse fields like geomatics, manufacturing and medicine. However, the processing of today's large point clouds is time-consuming, cumbersome and not automated enough. A basic step of post-processing is the registration of scans from different viewpoints. At present this is still done using artificial targets or tie points, mostly by manual clicking. The aim of this registration step is a coarse alignment, which can then be improved with the existing algorithm for fine registration. The focus of this paper is to provide such a coarse registration in a fully automatic fashion, and without placing any target objects in the scene. The basic idea is to use virtual tie points generated by intersecting planar surfaces in the scene. Such planes are detected in the data with RANSAC and optimally fitted using least squares estimation. Due to the huge amount of recorded points, planes can be determined very accurately, resulting in well-defined tie points. Given two sets of potential tie points recovered in two different scans, registration is performed by searching for the assignment which preserves the geometric configuration of the largest possible subset of all tie points. Since exhaustive search over all possible assignments is intractable even for moderate numbers of points, the search is guided by matching individual pairs of tie points with the help of a novel descriptor based on the properties of a point's parent planes. Experiments show that the proposed method is able to successfully coarse register TLS point clouds without the need for artificial targets.
Statistical signatures of a targeted search by bacteria

NASA Astrophysics Data System (ADS)

Jashnsaz, Hossein; Anderson, Gregory G.; Pressé, Steve

2017-12-01

Chemoattractant gradients are rarely well-controlled in nature and recent attention has turned to bacterial chemotaxis toward typical bacterial food sources such as food patches or even bacterial prey. In environments with localized food sources reminiscent of a bacterium’s natural habitat, striking phenomena—such as the volcano effect or banding—have been predicted or expected to emerge from chemotactic models. However, in practice, from limited bacterial trajectory data it is difficult to distinguish targeted searches from an untargeted search strategy for food sources. Here we use a theoretical model to identify statistical signatures of a targeted search toward point food sources, such as prey. Our model is constructed on the basis that bacteria use temporal comparisons to bias their random walk, exhibit finite memory and are subject to random (Brownian) motion as well as signaling noise. The advantage with using a stochastic model-based approach is that a stochastic model may be parametrized from individual stochastic bacterial trajectories but may then be used to generate a very large number of simulated trajectories to explore average behaviors obtained from stochastic search strategies. For example, our model predicts that a bacterium’s diffusion coefficient increases as it approaches the point source and that, in the presence of multiple sources, bacteria may take substantially longer to locate their first source giving the impression of an untargeted search strategy.
Object tracking based on harmony search: comparative study

NASA Astrophysics Data System (ADS)

Gao, Ming-Liang; He, Xiao-Hai; Luo, Dai-Sheng; Yu, Yan-Mei

2012-10-01

Visual tracking can be treated as an optimization problem. A new meta-heuristic optimal algorithm, Harmony Search (HS), was first applied to perform visual tracking by Fourie et al. As the authors point out, many subjects are still required in ongoing research. Our work is a continuation of Fourie's study, with four prominent improved variations of HS, namely Improved Harmony Search (IHS), Global-best Harmony Search (GHS), Self-adaptive Harmony Search (SHS) and Differential Harmony Search (DHS) adopted into the tracking system. Their performances are tested and analyzed on multiple challenging video sequences. Experimental results show that IHS is best, with DHS ranking second among the four improved trackers when the iteration number is small. However, the differences between all four reduced gradually, along with the increasing number of iterations.
Geology and geologic history of the Moscow-Pullman basin, Idaho and Washington, from late Grande Ronde to late Saddle Mountains time

USGS Publications Warehouse

Bush, John H; Garwood, Dean L; Dunlap, Pamela

2016-01-01

The Moscow-Pullman basin, located on the eastern margin of the Columbia River flood basalt province, consists of a subsurface mosaic of interlayered Miocene sediments and lava flows of the Imnaha, Grande Ronde, Wanapum, and Saddle Mountains Basalts of the Columbia River Basalt Group. This sequence is ~1800 ft (550 m) thick in the east around Moscow, Idaho, and exceeds 2300 ft (700 m) in the west at Pullman, Washington. Most flows entered from the west into a topographic low, partially surrounded by steep mountainous terrain. These flows caused a rapid rise in base level and deposition of immature sediments. This field guide focuses on the upper Grande Ronde Basalt, Wanapum Basalt, and sediments of the Latah Formation.Late Grande Ronde flows terminated midway into the basin to begin the formation of a topographic high that now separates a thick sediment wedge of the Vantage Member to the east of the high from a thin layer to the west. Disrupted by lava flows, streams were pushed from a west-flowing direction to a north-northwest orientation and drained the basin through a gap between steptoes toward Palouse, Washington. Emplacement of the Roza flow of the Wanapum Basalt against the western side of the topographic high was instrumental in this process, plugging west-flowing drainages and increasing deposition of Vantage sediments east of the high. The overlying basalt of Lolo covered both the Roza flow and Vantage sediments, blocking all drainages, and was in turn covered by sediments interlayered with local Saddle Mountains Basalt flows. Reestablishment of west-flowing drainages has been slow.The uppermost Grande Ronde, the Vantage, and the Wanapum contain what is known as the upper aquifer. The water supply is controlled, in part, by thickness, composition, and distribution of the Vantage sediments. A buried channel of the Vantage likely connects the upper aquifer to Palouse, Washington, outside the basin. This field guide locates outcrops; relates them to
Tracking coherent structures in massively-separated and turbulent flows

NASA Astrophysics Data System (ADS)

Rockwood, Matthew; Huang, Yangzi; Green, Melissa

2018-01-01

Coherent vortex structures are tracked in simulations of massively-separated and turbulent flows. Topological Lagrangian saddle points are found using intersections of the positive and negative finite-time Lyapunov exponent ridges, and these points are then followed in order to track individual coherent structure motion both in a complex interacting three-dimensional flow (turbulent channel) and during vortex formation (two-dimensional bluff body shedding). For a simulation of wall-bounded turbulence in a channel flow, tracking Lagrangian saddles shows that the average structure convection speed exhibits a similar trend as a previously published result based on velocity and pressure correlations, giving validity to the method. When this tracking method is applied in a study of a circular cylinder in cross-flow it shows that Lagrangian saddles rapidly accelerate away from the cylinder surface as the vortex sheds. This saddle behavior is compared with the time-resolved static pressure distribution on the circular cylinder, yielding locations on a cylinder surface where common sensors could detect this phenomenon, which is not available from force measurements or vortex circulation calculations. The current method of tracking coherent structures yields insight into the behavior of the coherent structures in both of the diverse flows presented, highlighting the breadth of its potential application.
Friedel oscillation near a van Hove singularity in two-dimensional Dirac materials

NASA Astrophysics Data System (ADS)

Lu, Chi-Ken

2016-02-01

We consider Friedel oscillation in the two-dimensional Dirac materials when the Fermi level is near the van Hove singularity. Twisted graphene bilayer and the surface state of topological crystalline insulator are the representative materials which show low-energy saddle points that are feasible to probe by gating. We approximate the Fermi surface near saddle point with a hyperbola and calculate the static Lindhard response function. Employing a theorem of Lighthill, the induced charge density δ n due to an impurity is obtained and the algebraic decay of δ n is determined by the singularity of the static response function. Although a hyperbolic Fermi surface is rather different from a circular one, the static Lindhard response function in the present case shows a singularity similar with the response function associated with circular Fermi surface, which leads to the δ n\\propto {{R}-2} at large distance R. The dependences of charge density on the Fermi energy are different. Consequently, it is possible to observe in twisted graphene bilayer the evolution that δ n\\propto {{R}-3} near Dirac point changes to δ n\\propto {{R}-2} above the saddle point. Measurements using scanning tunnelling microscopy around the impurity sites could verify the prediction.
Transient spatiotemporal chaos in the Morris-Lecar neuronal ring network.

PubMed

Keplinger, Keegan; Wackerbauer, Renate

2014-03-01

Transient behavior is thought to play an integral role in brain functionality. Numerical simulations of the firing activity of diffusively coupled, excitable Morris-Lecar neurons reveal transient spatiotemporal chaos in the parameter regime below the saddle-node on invariant circle bifurcation point. The neighborhood of the chaotic saddle is reached through perturbations of the rest state, in which few initially active neurons at an effective spatial distance can initiate spatiotemporal chaos. The system escapes from the neighborhood of the chaotic saddle to either the rest state or to a state of pulse propagation. The lifetime of the chaotic transients is manipulated in a statistical sense through a singular application of a synchronous perturbation to a group of neurons.

A nine-dimensional ab initio global potential energy surface for the H2O+ + H2 → H3O+ + H reaction

NASA Astrophysics Data System (ADS)

Li, Anyang; Guo, Hua

2014-06-01

An accurate full-dimensional global potential energy surface (PES) is developed for the title reaction. While the long-range interactions in the reactant asymptote are represented by an analytical expression, the interaction region of the PES is fit to more than 81 000 of ab initio points at the UCCSD(T)-F12b/AVTZ level using the permutation invariant polynomial neural network approach. Fully symmetric with respect to permutation of all four hydrogen atoms, the PES provides a faithful representation of the ab initio points, with a root mean square error of 1.8 meV or 15 cm-1. The reaction path for this exoergic reaction features an attractive and barrierless entrance channel, a submerged saddle point, a shallow H4O+ well, and a barrierless exit channel. The rate coefficients for the title reaction and kinetic isotope effect have been determined on this PES using quasi-classical trajectories, and they are in good agreement with available experimental data. It is further shown that the H2O+ rotational enhancement of reactivity observed experimentally can be traced to the submerged saddle point. Using our recently proposed Sudden Vector Projection model, we demonstrate that a rotational degree of freedom of the H2O+ reactant is strongly coupled with the reaction coordinate at this saddle point, thus unraveling the origin of the pronounced mode specificity in this reaction.
Basin stability measure of different steady states in coupled oscillators

NASA Astrophysics Data System (ADS)

Rakshit, Sarbendu; Bera, Bidesh K.; Majhi, Soumen; Hens, Chittaranjan; Ghosh, Dibakar

2017-04-01

In this report, we investigate the stabilization of saddle fixed points in coupled oscillators where individual oscillators exhibit the saddle fixed points. The coupled oscillators may have two structurally different types of suppressed states, namely amplitude death and oscillation death. The stabilization of saddle equilibrium point refers to the amplitude death state where oscillations are ceased and all the oscillators converge to the single stable steady state via inverse pitchfork bifurcation. Due to multistability features of oscillation death states, linear stability theory fails to analyze the stability of such states analytically, so we quantify all the states by basin stability measurement which is an universal nonlocal nonlinear concept and it interplays with the volume of basins of attractions. We also observe multi-clustered oscillation death states in a random network and measure them using basin stability framework. To explore such phenomena we choose a network of coupled Duffing-Holmes and Lorenz oscillators which are interacting through mean-field coupling. We investigate how basin stability for different steady states depends on mean-field density and coupling strength. We also analytically derive stability conditions for different steady states and confirm by rigorous bifurcation analysis.
Intermediate states and structure evolution in the free-falling process of the dislocation in graphene

NASA Astrophysics Data System (ADS)

Wang, Shaofeng; Yao, Yin; Bai, Jianhui; Wang, Rui

2017-04-01

This paper investigated the intermediate states and the structure evolution of the dislocation in graphene when it falls freely from the saddle point of the energy landscape. The O-type dislocation, an unstable equilibrium structure located at the saddle point, is obtained from the lattice theory of the dislocation structure and improved by the ab initio calculation to take the buckling into account. Intermediate states along the kinetics path in the falling process are obtained from the ab initio simulation. Once the dislocation falls from the saddle point to the energy valley, this O-type dislocation transforms into the stable structure that is referred to as the B-type dislocation, and in the meantime, it moves a distance that equals half a Burgers vector. The structure evolution and the energy variation in the free-falling process are revealed explicitly. It is observed that rather than smooth change, a platform manifests itself in the energy curve. The unusual behaviour in the energy curve is mainly originated from symmetry breaking and bond formation in the dislocation core. The results can provide deep insight in the mechanism of the brittle feature of covalent materials.
Quality Dimensions of Internet Search Engines.

ERIC Educational Resources Information Center

Xie, M.; Wang, H.; Goh, T. N.

1998-01-01

Reviews commonly used search engines (AltaVista, Excite, infoseek, Lycos, HotBot, WebCrawler), focusing on existing comparative studies; considers quality dimensions from the customer's point of view based on a SERVQUAL framework; and groups these quality expectations in five dimensions: tangibles, reliability, responsiveness, assurance, and…
Flow topology of rare back flow events and critical points in turbulent channels and toroidal pipes

NASA Astrophysics Data System (ADS)

Chin, C.; Vinuesa, R.; Örlü, R.; Cardesa, J. I.; Noorani, A.; Schlatter, P.; Chong, M. S.

2018-04-01

A study of the back flow events and critical points in the flow through a toroidal pipe at friction Reynolds number Re τ ≈ 650 is performed and compared with the results in a turbulent channel flow at Re τ ≈ 934. The statistics and topological properties of the back flow events are analysed and discussed. Conditionally-averaged flow fields in the vicinity of the back flow event are obtained, and the results for the torus show a similar streamwise wall-shear stress topology which varies considerably for the spanwise wall-shear stress when compared to the channel flow. The comparison between the toroidal pipe and channel flows also shows fewer back flow events and critical points in the torus. This cannot be solely attributed to differences in Reynolds number, but is a clear effect of the secondary flow present in the toroidal pipe. A possible mechanism is the effect of the secondary flow present in the torus, which convects momentum from the inner to the outer bend through the core of the pipe, and back from the outer to the inner bend through the pipe walls. In the region around the critical points, the skin-friction streamlines and vorticity lines exhibit similar flow characteristics with a node and saddle pair for both flows. These results indicate that back flow events and critical points are genuine features of wall-bounded turbulence, and are not artifacts of specific boundary or inflow conditions in simulations and/or measurement uncertainties in experiments.
JSC Search System Usability Case Study

NASA Technical Reports Server (NTRS)

Meza, David; Berndt, Sarah

2014-01-01

The advanced nature of "search" has facilitated the movement from keyword match to the delivery of every conceivable information topic from career, commerce, entertainment, learning... the list is infinite. At NASA Johnson Space Center (JSC ) the Search interface is an important means of knowledge transfer. By indexing multiple sources between directorates and organizations, the system's potential is culture changing in that through search, knowledge of the unique accomplishments in engineering and science can be seamlessly passed between generations. This paper reports the findings of an initial survey, the first of a four part study to help determine user sentiment on the intranet, or local (JSC) enterprise search environment as well as the larger NASA enterprise. The survey is a means through which end users provide direction on the development and transfer of knowledge by way of the search experience. The ideal is to identify what is working and what needs to be improved from the users' vantage point by documenting: (1) Where users are satisfied/dissatisfied (2) Perceived value of interface components (3) Gaps which cause any disappointment in search experience. The near term goal is it to inform JSC search in order to improve users' ability to utilize existing services and infrastructure to perform tasks with a shortened life cycle. Continuing steps include an agency based focus with modified questions to accomplish a similar purpose
Staleness Among Web Search Engines.

ERIC Educational Resources Information Center

Koehler, Wallace

1998-01-01

Describes a study of four major Web search engines that tested for staleness, a condition when a significant number of the hits it returns point to Web pages or server-level domains (SLD) that are no longer viable. Results of tests of URLs with AltaVista, HotBot, InfoSeek, and Open Text are discussed. (Author/LRW)
Ion extraction from a saddle antenna RF surface plasma source

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

Dudnikov, V., E-mail: vadim@muonsinc.com; Johnson, R. P.; Han, B.

Existing RF Surface Plasma Sources (SPS) for accelerators have specific efficiencies for H{sup +} and H{sup −} ion generation around 3 to 5 mA/cm{sup 2} per kW, where about 50 kW of RF power is typically needed for 50 mA beam current production. The Saddle Antenna (SA) SPS described here was developed to improve H{sup −} ion production efficiency and SPS reliability and availability. At low RF power, the efficiency of positive ion generation in the plasma has been improved to 200 mA/cm{sup 2} per kW of RF power at 13.56 MHz. Initial cesiation of the SPS was performed bymore » heating cesium chromate cartridges by discharge as was done in the very first versions of the SPS. A small oven to decompose cesium compounds and alloys was developed and tested. After cesiation, the current of negative ions to the collector was increased from 1 mA to 10 mA with RF power ∼1.5 kW in the plasma (6 mm diameter emission aperture) and up to 30 mA with ∼4 kW RF power in the plasma and 250 Gauss longitudinal magnetic field. The ratio of electron current to negative ion current was improved from 30 to 2. Stable generation of H{sup −} beam without intensity degradation was demonstrated in the AlN discharge chamber for a long time at high discharge power in an RF SPS with an external antenna. Continuous wave (CW) operation of the SA SPS has been tested on the small test stand. The general design of the CW SA SPS is based on the pulsed version. Some modifications were made to improve the cooling and cesiation stability. The extracted collector current can be increased significantly by optimizing the longitudinal magnetic field in the discharge chamber. CW operation with negative ion extraction was tested with RF power up to 1.8 kW from the generator (∼1.2 kW in the plasma) with production up to Ic=7 mA. Long term operation was tested with 1.2 kW from the RF generator (∼0.8 kW in the plasma) with production of Ic=5 mA, Iex ∼15 mA (Uex=8 kV, Uc=14 kV)« less
Ion extraction from a saddle antenna RF surface plasma source

NASA Astrophysics Data System (ADS)

Dudnikov, V.; Johnson, R. P.; Han, B.; Murray, S.; Pennisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R.; Breitschopf, J.; Dudnikova, G.

2015-04-01

Existing RF Surface Plasma Sources (SPS) for accelerators have specific efficiencies for H+ and H- ion generation around 3 to 5 mA/cm2 per kW, where about 50 kW of RF power is typically needed for 50 mA beam current production. The Saddle Antenna (SA) SPS described here was developed to improve H- ion production efficiency and SPS reliability and availability. At low RF power, the efficiency of positive ion generation in the plasma has been improved to 200 mA/cm2 per kW of RF power at 13.56 MHz. Initial cesiation of the SPS was performed by heating cesium chromate cartridges by discharge as was done in the very first versions of the SPS. A small oven to decompose cesium compounds and alloys was developed and tested. After cesiation, the current of negative ions to the collector was increased from 1 mA to 10 mA with RF power ˜1.5 kW in the plasma (6 mm diameter emission aperture) and up to 30 mA with ˜4 kW RF power in the plasma and 250 Gauss longitudinal magnetic field. The ratio of electron current to negative ion current was improved from 30 to 2. Stable generation of H- beam without intensity degradation was demonstrated in the AlN discharge chamber for a long time at high discharge power in an RF SPS with an external antenna. Continuous wave (CW) operation of the SA SPS has been tested on the small test stand. The general design of the CW SA SPS is based on the pulsed version. Some modifications were made to improve the cooling and cesiation stability. The extracted collector current can be increased significantly by optimizing the longitudinal magnetic field in the discharge chamber. CW operation with negative ion extraction was tested with RF power up to 1.8 kW from the generator (˜1.2 kW in the plasma) with production up to Ic=7 mA. Long term operation was tested with 1.2 kW from the RF generator (˜0.8 kW in the plasma) with production of Ic=5 mA, Iex ˜15 mA (Uex=8 kV, Uc=14 kV).
Method and system for efficiently searching an encoded vector index

DOEpatents

Bui, Thuan Quang; Egan, Randy Lynn; Kathmann, Kevin James

2001-09-04

Method and system aspects for efficiently searching an encoded vector index are provided. The aspects include the translation of a search query into a candidate bitmap, and the mapping of data from the candidate bitmap into a search result bitmap according to entry values in the encoded vector index. Further, the translation includes the setting of a bit in the candidate bitmap for each entry in a symbol table that corresponds to candidate of the search query. Also included in the mapping is the identification of a bit value in the candidate bitmap pointed to by an entry in an encoded vector.
Identification of the ideal clutter metric to predict time dependence of human visual search

NASA Astrophysics Data System (ADS)

Cartier, Joan F.; Hsu, David H.

1995-05-01

The Army Night Vision and Electronic Sensors Directorate (NVESD) has recently performed a human perception experiment in which eye tracker measurements were made on trained military observers searching for targets in infrared images. This data offered an important opportunity to evaluate a new technique for search modeling. Following the approach taken by Jeff Nicoll, this model treats search as a random walk in which the observers are in one of two states until they quit: they are either searching, or they are wandering around looking for a point of interest. When wandering they skip rapidly from point to point. When examining they move more slowly, reflecting the fact that target discrimination requires additional thought processes. In this paper we simulate the random walk, using a clutter metric to assign relative attractiveness to points of interest within the image which are competing for the observer's attention. The NVESD data indicates that a number of standard clutter metrics are good estimators of the apportionment of observer's time between wandering and examining. Conversely, the apportionment of observer time spent wandering and examining could be used to reverse engineer the ideal clutter metric which would most perfectly describe the behavior of the group of observers. It may be possible to use this technique to design the optimal clutter metric to predict performance of visual search.
Improving GPU-accelerated adaptive IDW interpolation algorithm using fast kNN search.

PubMed

Mei, Gang; Xu, Nengxiong; Xu, Liangliang

2016-01-01

This paper presents an efficient parallel Adaptive Inverse Distance Weighting (AIDW) interpolation algorithm on modern Graphics Processing Unit (GPU). The presented algorithm is an improvement of our previous GPU-accelerated AIDW algorithm by adopting fast k-nearest neighbors (kNN) search. In AIDW, it needs to find several nearest neighboring data points for each interpolated point to adaptively determine the power parameter; and then the desired prediction value of the interpolated point is obtained by weighted interpolating using the power parameter. In this work, we develop a fast kNN search approach based on the space-partitioning data structure, even grid, to improve the previous GPU-accelerated AIDW algorithm. The improved algorithm is composed of the stages of kNN search and weighted interpolating. To evaluate the performance of the improved algorithm, we perform five groups of experimental tests. The experimental results indicate: (1) the improved algorithm can achieve a speedup of up to 1017 over the corresponding serial algorithm; (2) the improved algorithm is at least two times faster than our previous GPU-accelerated AIDW algorithm; and (3) the utilization of fast kNN search can significantly improve the computational efficiency of the entire GPU-accelerated AIDW algorithm.
Time-Dependent Searches for Point Sources of Neutrinos with the 4O-String and 22-String Configurations of IceCube

NASA Technical Reports Server (NTRS)

Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.;

2012-01-01

This paper presents four searches for flaring sources of neutrinos using the IceCube neutrino telescope. For the first time, a search is performed over the entire parameter space of energy, direction, and time with sensitivity to neutrino flares lasting between 20 micro-s and a year duration from astrophysical sources. Searches that integrate over time are less sensitive to flares because they are affected by a larger background of atmospheric neutrinos and muons that can be reduced by the use of additional timing information. Flaring sources considered here, such as active galactic nuclei, soft gamma-ray repeaters, and gamma-ray bursts, are promising candidate neutrino emitters. Two searches are "untriggered" in the sense that they look for any possible flare in the entire sky and from a predefined catalog of sources from which photon flares have been recorded. The other two searches are triggered by multi-wavelength information on flares from blazars and from a soft gamma-ray repeater. One triggered search uses lightcurves from Fermi-LAT which provides continuous monitoring. A second triggered search uses information where the flux states have been measured only for short periods of time near the flares. The untriggered searches use data taken by 40 strings of IceCube between 2008 April 5 and 2009 May 20. The triggered searches also use data taken by the 22-string configuration of IceCube operating between 2007 May 31 and 2008 April 5. The results from all four searches are compatible with a fluctuation of the background.

Bi-SOC-states in one-dimensional random cellular automaton

NASA Astrophysics Data System (ADS)

Czechowski, Zbigniew; Budek, Agnieszka; Białecki, Mariusz

2017-10-01

Two statistically stationary states with power-law scaling of avalanches are found in a simple 1 D cellular automaton. Features of the fixed points, the spiral saddle and the saddle with index 1, are investigated. The migration of states of the automaton between these two self-organized criticality states is demonstrated during evolution of the system in computer simulations. The automaton, being a slowly driven system, can be applied as a toy model of earthquake supercycles.
Searching for periodic sources with LIGO. II. Hierarchical searches

NASA Astrophysics Data System (ADS)

Brady, Patrick R.; Creighton, Teviet

2000-04-01

The detection of quasi-periodic sources of gravitational waves requires the accumulation of signal to noise over long observation times. This represents the most difficult data analysis problem facing experimenters with detectors such as those at LIGO. If not removed, Earth-motion induced Doppler modulations and intrinsic variations of the gravitational-wave frequency make the signals impossible to detect. These effects can be corrected (removed) using a parametrized model for the frequency evolution. In a previous paper, we introduced such a model and computed the number of independent parameter space points for which corrections must be applied to the data stream in a coherent search. Since this number increases with the observation time, the sensitivity of a search for continuous gravitational-wave signals is computationally bound when data analysis proceeds at a similar rate to data acquisition. In this paper, we extend the formalism developed by Brady et al. [Phys. Rev. D 57, 2101 (1998)], and we compute the number of independent corrections Np(ΔT,N) required for incoherent search strategies. These strategies rely on the method of stacked power spectra-a demodulated time series is divided into N segments of length ΔT, each segment is Fourier transformed, a power spectrum is computed, and the N spectra are summed up. This method is incoherent; phase information is lost from segment to segment. Nevertheless, power from a signal with fixed frequency (in the corrected time series) is accumulated in a single frequency bin, and amplitude signal to noise accumulates as ~N1/4 (assuming the segment length ΔT is held fixed). For fixed available computing power, there are optimal values for N and ΔT which maximize the sensitivity of a search in which data analysis takes a total time NΔT. We estimate that the optimal sensitivity of an all-sky search that uses incoherent stacks is a factor of 2-4 better than achieved using coherent Fourier transforms, assuming the
Absolute Points for Multiple Assignment Problems

ERIC Educational Resources Information Center

Adlakha, V.; Kowalski, K.

2006-01-01

An algorithm is presented to solve multiple assignment problems in which a cost is incurred only when an assignment is made at a given cell. The proposed method recursively searches for single/group absolute points to identify cells that must be loaded in any optimal solution. Unlike other methods, the first solution is the optimal solution. The…
Lagrangian coherent structure analysis in the three-dimensional wake of a bio-inspired trapezoidal pitching panel

NASA Astrophysics Data System (ADS)

Kumar, Rajeev; King, Justin; Green, Melissa

2017-11-01

Three-dimensional Lagrangian analysis using the finite-time Lyapunov exponent (FTLE) field has been carried out on experimentally captured wake downstream of an oscillating trapezoidal panel. The trapezoidal geometry of the panel served as a simple model of a fish caudal fin. Three-dimensional FTLE isosurface appears as a shell wrapped around the wake vortex structures. A slice through the isosurfaces results in the familiar two-dimensional FTLE ridges. The attracting ridges (nFTLE) and the repelling ridges (pFTLE) are near-material lines and their intersections are analogous to topological saddle points in the flow field. A vortex-ring-based wake structure induces a streamwise momentum jet, evolution of which appears to be related to the timing of saddle point generation and behavior at the trailing edge. The time of release of these saddles at the trailing edge inside a pitching period appears to coincide with thrust extrema in similar experimental and numerical studies on foils and fins published in the literature. The merger of a pair of saddles from two consecutively shed vortices at a downstream location coincides with the occurrence of wake breakdown and precedes the formation of interconnected vortex loops and beginning of momentum-deficit zone in the time-averaged sense. This work was supported by the Office of Naval Research under ONR Award No. N00014-14-1-0418.
Searching for life in the universe: lessons from the earth

NASA Technical Reports Server (NTRS)

Nealson, K. H.

2001-01-01

Space programs will soon allow us to search for life in situ on Mars and to return samples for analysis. A major focal point is to search for evidence of present or past life in these samples, evidence that, if found, would have far-reaching consequences for both science and religion. A search strategy will consider the entire gamut of life on our own planet, using that information to frame a search that would recognize life even if it were fundamentally different from that we know on Earth. We discuss here how the lessons learned from the study of life on Earth can be used to allow us to develop a general strategy for the search for life in the Universe.
Searching for life in the universe: lessons from the earth.

PubMed

Nealson, K H

2001-12-01

Space programs will soon allow us to search for life in situ on Mars and to return samples for analysis. A major focal point is to search for evidence of present or past life in these samples, evidence that, if found, would have far-reaching consequences for both science and religion. A search strategy will consider the entire gamut of life on our own planet, using that information to frame a search that would recognize life even if it were fundamentally different from that we know on Earth. We discuss here how the lessons learned from the study of life on Earth can be used to allow us to develop a general strategy for the search for life in the Universe.
Search for the critical point of the nuclear matter phase diagram. first results from the beam energy SCAN program at RHIC

DOE PAGES

Odyniec, Grazyna

2012-01-01

In 2010, the Relativistic Heavy Ion Collider (RHIC) launched a multi-step experimental program to investigate the QCD Phase Diagram in general, and to search for the QCD Critical Point (CP) and/or 1st order phase transition in particular. The BES (Beam Energy Scan) program involves an “energy scan” of Au+Au collisions from the top RHIC energy (√s = 200 GeV) down to energies as low as 5 GeV in NN center of mass. During the first BES run (2010), data were collected at 7.7, 11.5 and 39 GeV. It was complemented in 2011 by two other data sets at 27 andmore » 19.6 GeV. The preparations for the remaining data taking at √s = 5 GeV are in progress. The overview of the BES program and the first experimental results are presented and discussed.« less

Search for the critical point of the nuclear matter phase diagram. first results from the beam energy SCAN program at RHIC

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

Odyniec, Grazyna

In 2010, the Relativistic Heavy Ion Collider (RHIC) launched a multi-step experimental program to investigate the QCD Phase Diagram in general, and to search for the QCD Critical Point (CP) and/or 1st order phase transition in particular. The BES (Beam Energy Scan) program involves an “energy scan” of Au+Au collisions from the top RHIC energy (√s = 200 GeV) down to energies as low as 5 GeV in NN center of mass. During the first BES run (2010), data were collected at 7.7, 11.5 and 39 GeV. It was complemented in 2011 by two other data sets at 27 andmore » 19.6 GeV. The preparations for the remaining data taking at √s = 5 GeV are in progress. The overview of the BES program and the first experimental results are presented and discussed.« less
Visual Exploratory Search of Relationship Graphs on Smartphones

PubMed Central

Ouyang, Jianquan; Zheng, Hao; Kong, Fanbin; Liu, Tianming

2013-01-01

This paper presents a novel framework for Visual Exploratory Search of Relationship Graphs on Smartphones (VESRGS) that is composed of three major components: inference and representation of semantic relationship graphs on the Web via meta-search, visual exploratory search of relationship graphs through both querying and browsing strategies, and human-computer interactions via the multi-touch interface and mobile Internet on smartphones. In comparison with traditional lookup search methodologies, the proposed VESRGS system is characterized with the following perceived advantages. 1) It infers rich semantic relationships between the querying keywords and other related concepts from large-scale meta-search results from Google, Yahoo! and Bing search engines, and represents semantic relationships via graphs; 2) the exploratory search approach empowers users to naturally and effectively explore, adventure and discover knowledge in a rich information world of interlinked relationship graphs in a personalized fashion; 3) it effectively takes the advantages of smartphones’ user-friendly interfaces and ubiquitous Internet connection and portability. Our extensive experimental results have demonstrated that the VESRGS framework can significantly improve the users’ capability of seeking the most relevant relationship information to their own specific needs. We envision that the VESRGS framework can be a starting point for future exploration of novel, effective search strategies in the mobile Internet era. PMID:24223936
Combined semantic and similarity search in medical image databases

NASA Astrophysics Data System (ADS)

Seifert, Sascha; Thoma, Marisa; Stegmaier, Florian; Hammon, Matthias; Kramer, Martin; Huber, Martin; Kriegel, Hans-Peter; Cavallaro, Alexander; Comaniciu, Dorin

2011-03-01

The current diagnostic process at hospitals is mainly based on reviewing and comparing images coming from multiple time points and modalities in order to monitor disease progression over a period of time. However, for ambiguous cases the radiologist deeply relies on reference literature or second opinion. Although there is a vast amount of acquired images stored in PACS systems which could be reused for decision support, these data sets suffer from weak search capabilities. Thus, we present a search methodology which enables the physician to fulfill intelligent search scenarios on medical image databases combining ontology-based semantic and appearance-based similarity search. It enabled the elimination of 12% of the top ten hits which would arise without taking the semantic context into account.
Optical signature of Weyl electronic structures in tantalum pnictides Ta P n (P n = P, As)

NASA Astrophysics Data System (ADS)

Kimura, Shin-ichi; Yokoyama, Hiroko; Watanabe, Hiroshi; Sichelschmidt, Jörg; Süß, Vicky; Schmidt, Marcus; Felser, Claudia

2017-08-01

To investigate the electronic structure of Weyl semimetals Ta P n (P n = P, As), optical conductivity [σ (ω )] spectra are measured over a wide range of photon energies and temperatures, and these measured values are compared with band calculations. Two significant structures can be observed: a bending structure at ℏ ω ˜85 meV in TaAs, and peaks at ℏ ω ˜ 50 meV (TaP) and ˜30 meV (TaAs). The bending structure can be explained by the interband transition between saddle points connecting a set of W2 Weyl points. The temperature dependence of the peak intensity can be fitted by assuming the interband transition between saddle points connecting a set of W1 Weyl points. Owing to the different temperature dependence of the Drude weight in both materials, it is found that the Weyl points of TaAs are located near the Fermi level, whereas those of TaP are further away.
Heavy Higgs searches: flavour matters

NASA Astrophysics Data System (ADS)

Gori, Stefania; Grojean, Christophe; Juste, Aurelio; Paul, Ayan

2018-01-01

We point out that the stringent lower bounds on the masses of additional electrically neutral and charged Higgs bosons crucially depend on the flavour structure of their Yukawa interactions. We show that these bounds can easily be evaded by the introduction of flavour-changing neutral currents in the Higgs sector. As an illustration, we study the phenomenology of a two Higgs doublet model with a Yukawa texture singling out the third family of quarks and leptons. We combine constraints from low-energy flavour physics measurements, LHC measurements of the 125 GeV Higgs boson rates, and LHC searches for new heavy Higgs bosons. We propose novel LHC searches that could be performed in the coming years to unravel the existence of these new Higgs bosons.
Quantum transitions through cosmological singularities

NASA Astrophysics Data System (ADS)

Bramberger, Sebastian F.; Hertog, Thomas; Lehners, Jean-Luc; Vreys, Yannick

2017-07-01

In a quantum theory of cosmology spacetime behaves classically only in limited patches of the configuration space on which the wave function of the universe is defined. Quantum transitions can connect classical evolution in different patches. Working in the saddle point approximation and in minisuperspace we compute quantum transitions connecting inflationary histories across a de Sitter like throat or a singularity. This supplies probabilities for how an inflating universe, when evolved backwards, transitions and branches into an ensemble of histories on the opposite side of a quantum bounce. Generalising our analysis to scalar potentials with negative regions we identify saddle points describing a quantum transition between a classically contracting, crunching ekpyrotic phase and an inflationary universe.
A method to approximate a closest loadability limit using multiple load flow solutions

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

Yorino, Naoto; Harada, Shigemi; Cheng, Haozhong

A new method is proposed to approximate a closest loadability limit (CLL), or closest saddle node bifurcation point, using a pair of multiple load flow solutions. More strictly, the obtainable points by the method are the stationary points including not only CLL but also farthest and saddle points. An operating solution and a low voltage load flow solution are used to efficiently estimate the node injections at a CLL as well as the left and right eigenvectors corresponding to the zero eigenvalue of the load flow Jacobian. They can be used in monitoring loadability margin, in identification of weak spotsmore » in a power system and in the examination of an optimal control against voltage collapse. Most of the computation time of the proposed method is taken in calculating the load flow solution pair. The remaining computation time is less than that of an ordinary load flow.« less
Characterization of the Atacama B-mode Search

NASA Astrophysics Data System (ADS)

Simon, S. M.; Raghunathan, S.; Appel, J. W.; Becker, D. T.; Campusano, L. E.; Cho, H. M.; Essinger-Hileman, T.; Ho, S. P.; Irwin, K. D.; Jarosik, N.; Kusaka, A.; Niemack, M. D.; Nixon, G. W.; Nolta, M. R.; Page, L. A.; Palma, G. A.; Parker, L. P.; Sievers, J. L.; Staggs, S. T.; Visnjic, K.

2014-07-01

The Atacama B-mode Search (ABS), which began observations in February of 2012, is a crossed-Dragone telescope located at an elevation of 5190 m in the Atacama Desert in Chile. ABS is searching for the B-mode polarization spectrum of the cosmic microwave background (CMB) at large angular scales from multipole moments of ` ~ 50 ~ 500, a range that includes the primor- dial B-mode peak from inflationary gravity waves at ~ 100. The ABS focal plane consists of 240 pixels sensitive to 145 GHz, each containing two transition-edge sensor bolometers coupled to orthogonal polarizations with a planar ortho-mode transducer. An ambient-temperature con- tinuously rotating half-wave plate and 4 K optics make the ABS instrument unique. We discuss the characterization of the detector spectral responses with a Fourier transform spectrometer and demonstrate that the pointing model is adequate. We also present measurements of the beam from point sources and compare them with simulations.
Search predicts and changes patience in intertemporal choice

PubMed Central

Johnson, Eric J.

2017-01-01

Intertemporal choice impacts many important outcomes, such as decisions about health, education, wealth, and the environment. However, the psychological processes underlying decisions involving outcomes at different points in time remain unclear, limiting opportunities to intervene and improve people’s patience. This research examines information-search strategies used during intertemporal choice and their impact on decisions. In experiment 1, we demonstrate that search strategies vary substantially across individuals. We subsequently identify two distinct search strategies across individuals. Comparative searchers, who compare features across options, discount future options less and are more susceptible to acceleration versus delay framing than integrative searchers, who integrate the features of an option. Experiment 2 manipulates search using an unobtrusive method to establish a causal relationship between strategy and choice, randomly assigning participants to conditions promoting either comparative or integrative search. Again, comparative search promotes greater patience than integrative search. Additionally, when participants adopt a comparative search strategy, they also exhibit greater effects of acceleration versus delay framing. Although most participants reported that the manipulation did not change their behavior, promoting comparative search decreased discounting of future rewards substantially and speeded patient choices. These findings highlight the central role that heterogeneity in psychological processes plays in shaping intertemporal choice. Importantly, these results indicate that theories that ignore variability in search strategies may be inadvertently aggregating over different subpopulations that use very different processes. The findings also inform interventions in choice architecture to increase patience and improve consumer welfare. PMID:29078303
Fast adaptive diamond search algorithm for block-matching motion estimation using spatial correlation

NASA Astrophysics Data System (ADS)

Park, Sang-Gon; Jeong, Dong-Seok

2000-12-01

In this paper, we propose a fast adaptive diamond search algorithm (FADS) for block matching motion estimation. Many fast motion estimation algorithms reduce the computational complexity by the UESA (Unimodal Error Surface Assumption) where the matching error monotonically increases as the search moves away from the global minimum point. Recently, many fast BMAs (Block Matching Algorithms) make use of the fact that global minimum points in real world video sequences are centered at the position of zero motion. But these BMAs, especially in large motion, are easily trapped into the local minima and result in poor matching accuracy. So, we propose a new motion estimation algorithm using the spatial correlation among the neighboring blocks. We move the search origin according to the motion vectors of the spatially neighboring blocks and their MAEs (Mean Absolute Errors). The computer simulation shows that the proposed algorithm has almost the same computational complexity with DS (Diamond Search), but enhances PSNR. Moreover, the proposed algorithm gives almost the same PSNR as that of FS (Full Search), even for the large motion with half the computational load.
Search-based optimization

NASA Technical Reports Server (NTRS)

Wheeler, Ward C.

2003-01-01

The problem of determining the minimum cost hypothetical ancestral sequences for a given cladogram is known to be NP-complete (Wang and Jiang, 1994). Traditionally, point estimations of hypothetical ancestral sequences have been used to gain heuristic, upper bounds on cladogram cost. These include procedures with such diverse approaches as non-additive optimization of multiple sequence alignment, direct optimization (Wheeler, 1996), and fixed-state character optimization (Wheeler, 1999). A method is proposed here which, by extending fixed-state character optimization, replaces the estimation process with a search. This form of optimization examines a diversity of potential state solutions for cost-efficient hypothetical ancestral sequences and can result in greatly more parsimonious cladograms. Additionally, such an approach can be applied to other NP-complete phylogenetic optimization problems such as genomic break-point analysis. c2003 The Willi Hennig Society. Published by Elsevier Science (USA). All rights reserved.
BCM Search Launcher--an integrated interface to molecular biology data base search and analysis services available on the World Wide Web.

PubMed

Smith, R F; Wiese, B A; Wojzynski, M K; Davison, D B; Worley, K C

1996-05-01

The BCM Search Launcher is an integrated set of World Wide Web (WWW) pages that organize molecular biology-related search and analysis services available on the WWW by function, and provide a single point of entry for related searches. The Protein Sequence Search Page, for example, provides a single sequence entry form for submitting sequences to WWW servers that offer remote access to a variety of different protein sequence search tools, including BLAST, FASTA, Smith-Waterman, BEAUTY, PROSITE, and BLOCKS searches. Other Launch pages provide access to (1) nucleic acid sequence searches, (2) multiple and pair-wise sequence alignments, (3) gene feature searches, (4) protein secondary structure prediction, and (5) miscellaneous sequence utilities (e.g., six-frame translation). The BCM Search Launcher also provides a mechanism to extend the utility of other WWW services by adding supplementary hypertext links to results returned by remote servers. For example, links to the NCBI's Entrez data base and to the Sequence Retrieval System (SRS) are added to search results returned by the NCBI's WWW BLAST server. These links provide easy access to auxiliary information, such as Medline abstracts, that can be extremely helpful when analyzing BLAST data base hits. For new or infrequent users of sequence data base search tools, we have preset the default search parameters to provide the most informative first-pass sequence analysis possible. We have also developed a batch client interface for Unix and Macintosh computers that allows multiple input sequences to be searched automatically as a background task, with the results returned as individual HTML documents directly to the user's system. The BCM Search Launcher and batch client are available on the WWW at URL http:@gc.bcm.tmc.edu:8088/search-launcher.html.
Axion dark matter searches

DOE PAGES

Stern, Ian P.

2014-01-01

We report nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a μeV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 μeV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axionsmore » at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.« less
Combining local and global limitations of visual search.

PubMed

Põder, Endel

2017-04-01

There are different opinions about the roles of local interactions and central processing capacity in visual search. This study attempts to clarify the problem using a new version of relevant set cueing. A central precue indicates two symmetrical segments (that may contain a target object) within a circular array of objects presented briefly around the fixation point. The number of objects in the relevant segments, and density of objects in the array were varied independently. Three types of search experiments were run: (a) search for a simple visual feature (color, size, and orientation); (b) conjunctions of simple features; and (c) spatial configuration of simple features (rotated Ts). For spatial configuration stimuli, the results were consistent with a fixed global processing capacity and standard crowding zones. For simple features and their conjunctions, the results were different, dependent on the features involved. While color search exhibits virtually no capacity limits or crowding, search for an orientation target was limited by both. Results for conjunctions of features can be partly explained by the results from the respective features. This study shows that visual search is limited by both local interference and global capacity, and the limitations are different for different visual features.
A Minimal Path Searching Approach for Active Shape Model (ASM)-based Segmentation of the Lung.

PubMed

Guo, Shengwen; Fei, Baowei

2009-03-27

We are developing a minimal path searching method for active shape model (ASM)-based segmentation for detection of lung boundaries on digital radiographs. With the conventional ASM method, the position and shape parameters of the model points are iteratively refined and the target points are updated by the least Mahalanobis distance criterion. We propose an improved searching strategy that extends the searching points in a fan-shape region instead of along the normal direction. A minimal path (MP) deformable model is applied to drive the searching procedure. A statistical shape prior model is incorporated into the segmentation. In order to keep the smoothness of the shape, a smooth constraint is employed to the deformable model. To quantitatively assess the ASM-MP segmentation, we compare the automatic segmentation with manual segmentation for 72 lung digitized radiographs. The distance error between the ASM-MP and manual segmentation is 1.75 ± 0.33 pixels, while the error is 1.99 ± 0.45 pixels for the ASM. Our results demonstrate that our ASM-MP method can accurately segment the lung on digital radiographs.
A minimal path searching approach for active shape model (ASM)-based segmentation of the lung

NASA Astrophysics Data System (ADS)

Guo, Shengwen; Fei, Baowei

2009-02-01

We are developing a minimal path searching method for active shape model (ASM)-based segmentation for detection of lung boundaries on digital radiographs. With the conventional ASM method, the position and shape parameters of the model points are iteratively refined and the target points are updated by the least Mahalanobis distance criterion. We propose an improved searching strategy that extends the searching points in a fan-shape region instead of along the normal direction. A minimal path (MP) deformable model is applied to drive the searching procedure. A statistical shape prior model is incorporated into the segmentation. In order to keep the smoothness of the shape, a smooth constraint is employed to the deformable model. To quantitatively assess the ASM-MP segmentation, we compare the automatic segmentation with manual segmentation for 72 lung digitized radiographs. The distance error between the ASM-MP and manual segmentation is 1.75 +/- 0.33 pixels, while the error is 1.99 +/- 0.45 pixels for the ASM. Our results demonstrate that our ASM-MP method can accurately segment the lung on digital radiographs.
A Minimal Path Searching Approach for Active Shape Model (ASM)-based Segmentation of the Lung

PubMed Central

Guo, Shengwen; Fei, Baowei

2013-01-01

We are developing a minimal path searching method for active shape model (ASM)-based segmentation for detection of lung boundaries on digital radiographs. With the conventional ASM method, the position and shape parameters of the model points are iteratively refined and the target points are updated by the least Mahalanobis distance criterion. We propose an improved searching strategy that extends the searching points in a fan-shape region instead of along the normal direction. A minimal path (MP) deformable model is applied to drive the searching procedure. A statistical shape prior model is incorporated into the segmentation. In order to keep the smoothness of the shape, a smooth constraint is employed to the deformable model. To quantitatively assess the ASM-MP segmentation, we compare the automatic segmentation with manual segmentation for 72 lung digitized radiographs. The distance error between the ASM-MP and manual segmentation is 1.75 ± 0.33 pixels, while the error is 1.99 ± 0.45 pixels for the ASM. Our results demonstrate that our ASM-MP method can accurately segment the lung on digital radiographs. PMID:24386531
VisSearch: A Collaborative Web Searching Environment

ERIC Educational Resources Information Center

Lee, Young-Jin

2005-01-01

VisSearch is a collaborative Web searching environment intended for sharing Web search results among people with similar interests, such as college students taking the same course. It facilitates students' Web searches by visualizing various Web searching processes. It also collects the visualized Web search results and applies an association rule…
Deep first formal concept search.

PubMed

Zhang, Tao; Li, Hui; Hong, Wenxue; Yuan, Xiamei; Wei, Xinyu

2014-01-01

The calculation of formal concepts is a very important part in the theory of formal concept analysis (FCA); however, within the framework of FCA, computing all formal concepts is the main challenge because of its exponential complexity and difficulty in visualizing the calculating process. With the basic idea of Depth First Search, this paper presents a visualization algorithm by the attribute topology of formal context. Limited by the constraints and calculation rules, all concepts are achieved by the visualization global formal concepts searching, based on the topology degenerated with the fixed start and end points, without repetition and omission. This method makes the calculation of formal concepts precise and easy to operate and reflects the integrity of the algorithm, which enables it to be suitable for visualization analysis.
Stability boundaries for command augmentation systems

NASA Technical Reports Server (NTRS)

Shrivastava, P. C.

1987-01-01

The Stability Augmentation System (SAS) is a special case of the Command Augmentation System (CAS). Control saturation imposes bounds on achievable commands. The state equilibrium depends only on the open loop dynamics and control deflection. The control magnitude to achieve a desired command equilibrium is independent of the feedback gain. A feedback controller provides the desired response, maintains the system equilibrium under disturbances, but it does not affect the equilibrium values of states and control. The saturation boundaries change with commands, but the location of the equilibrium points in the saturated region remains unchanged. Nonzero command vectors yield saturation boundaries that are asymmetric with respect to the state equilibrium. Except for the saddle point case with MCE control law, the stability boundaries change with commands. For the cases of saddle point and unstable nodes, the region of stability decreases with increasing command magnitudes.

Barriers and decisions when answering clinical questions at the point of care: a grounded theory study.

PubMed

Cook, David A; Sorensen, Kristi J; Wilkinson, John M; Berger, Richard A

2013-11-25

Answering clinical questions affects patient-care decisions and is important to continuous professional development. The process of point-of-care learning is incompletely understood. To understand what barriers and enabling factors influence physician point-of-care learning and what decisions physicians face during this process. Focus groups with grounded theory analysis. Focus group discussions were transcribed and then analyzed using a constant comparative approach to identify barriers, enabling factors, and key decisions related to physician information-seeking activities. Academic medical center and outlying community sites. Purposive sample of 50 primary care and subspecialist internal medicine and family medicine physicians, interviewed in 11 focus groups. Insufficient time was the main barrier to point-of-care learning. Other barriers included the patient comorbidities and contexts, the volume of available information, not knowing which resource to search, doubt that the search would yield an answer, difficulty remembering questions for later study, and inconvenient access to computers. Key decisions were whether to search (reasons to search included infrequently seen conditions, practice updates, complex questions, and patient education), when to search (before, during, or after the clinical encounter), where to search (with the patient present or in a separate room), what type of resource to use (colleague or computer), what specific resource to use (influenced first by efficiency and second by credibility), and when to stop. Participants noted that key features of efficiency (completeness, brevity, and searchability) are often in conflict. Physicians perceive that insufficient time is the greatest barrier to point-of-care learning, and efficiency is the most important determinant in selecting an information source. Designing knowledge resources and systems to target key decisions may improve learning and patient care.
A universal preconditioner for simulating condensed phase materials.

PubMed

Packwood, David; Kermode, James; Mones, Letif; Bernstein, Noam; Woolley, John; Gould, Nicholas; Ortner, Christoph; Csányi, Gábor

2016-04-28

We introduce a universal sparse preconditioner that accelerates geometry optimisation and saddle point search tasks that are common in the atomic scale simulation of materials. Our preconditioner is based on the neighbourhood structure and we demonstrate the gain in computational efficiency in a wide range of materials that include metals, insulators, and molecular solids. The simple structure of the preconditioner means that the gains can be realised in practice not only when using expensive electronic structure models but also for fast empirical potentials. Even for relatively small systems of a few hundred atoms, we observe speedups of a factor of two or more, and the gain grows with system size. An open source Python implementation within the Atomic Simulation Environment is available, offering interfaces to a wide range of atomistic codes.
A universal preconditioner for simulating condensed phase materials

NASA Astrophysics Data System (ADS)

Packwood, David; Kermode, James; Mones, Letif; Bernstein, Noam; Woolley, John; Gould, Nicholas; Ortner, Christoph; Csányi, Gábor

2016-04-01

We introduce a universal sparse preconditioner that accelerates geometry optimisation and saddle point search tasks that are common in the atomic scale simulation of materials. Our preconditioner is based on the neighbourhood structure and we demonstrate the gain in computational efficiency in a wide range of materials that include metals, insulators, and molecular solids. The simple structure of the preconditioner means that the gains can be realised in practice not only when using expensive electronic structure models but also for fast empirical potentials. Even for relatively small systems of a few hundred atoms, we observe speedups of a factor of two or more, and the gain grows with system size. An open source Python implementation within the Atomic Simulation Environment is available, offering interfaces to a wide range of atomistic codes.
Automated Transition State Theory Calculations for High-Throughput Kinetics.

PubMed

Bhoorasingh, Pierre L; Slakman, Belinda L; Seyedzadeh Khanshan, Fariba; Cain, Jason Y; West, Richard H

2017-09-21

A scarcity of known chemical kinetic parameters leads to the use of many reaction rate estimates, which are not always sufficiently accurate, in the construction of detailed kinetic models. To reduce the reliance on these estimates and improve the accuracy of predictive kinetic models, we have developed a high-throughput, fully automated, reaction rate calculation method, AutoTST. The algorithm integrates automated saddle-point geometry search methods and a canonical transition state theory kinetics calculator. The automatically calculated reaction rates compare favorably to existing estimated rates. Comparison against high level theoretical calculations show the new automated method performs better than rate estimates when the estimate is made by a poor analogy. The method will improve by accounting for internal rotor contributions and by improving methods to determine molecular symmetry.
Representational flexibility and response control in a multistep multilocation search task.

PubMed

Zelazo, P D; Reznick, J S; Spinazzola, J

1998-03-01

Three experiments were conducted to explore the determinants of 2-year-olds' perseverative errors in a search task. In Experiment 1, children either retrieved an object during a preswitch phase or merely observed a hiding event. Active search produced perseveration on postswitch trials, but mere observation did not. In Experiment 2, similar results were found, even when active search occurred in the absence of observation. Finally, in Experiment 3, children observed a hiding event at 1 location on some pretest trials and simply retrieved an object at a different location on other trials. On test trials, in which an object was hidden at a 3rd location, children tended to search where they had searched previously. Together, the results indicate that active search is required to elicit perseveration, which points to failures of response control rather than representational inflexibility.
Search predicts and changes patience in intertemporal choice.

PubMed

Reeck, Crystal; Wall, Daniel; Johnson, Eric J

2017-11-07

Intertemporal choice impacts many important outcomes, such as decisions about health, education, wealth, and the environment. However, the psychological processes underlying decisions involving outcomes at different points in time remain unclear, limiting opportunities to intervene and improve people's patience. This research examines information-search strategies used during intertemporal choice and their impact on decisions. In experiment 1, we demonstrate that search strategies vary substantially across individuals. We subsequently identify two distinct search strategies across individuals. Comparative searchers, who compare features across options, discount future options less and are more susceptible to acceleration versus delay framing than integrative searchers, who integrate the features of an option. Experiment 2 manipulates search using an unobtrusive method to establish a causal relationship between strategy and choice, randomly assigning participants to conditions promoting either comparative or integrative search. Again, comparative search promotes greater patience than integrative search. Additionally, when participants adopt a comparative search strategy, they also exhibit greater effects of acceleration versus delay framing. Although most participants reported that the manipulation did not change their behavior, promoting comparative search decreased discounting of future rewards substantially and speeded patient choices. These findings highlight the central role that heterogeneity in psychological processes plays in shaping intertemporal choice. Importantly, these results indicate that theories that ignore variability in search strategies may be inadvertently aggregating over different subpopulations that use very different processes. The findings also inform interventions in choice architecture to increase patience and improve consumer welfare. Copyright © 2017 the Author(s). Published by PNAS.
In search of elementary spin 0 particles

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

Krasny, Mieczyslaw Witold, E-mail: krasny@lpnhep.in2p3.fr; Płaczek, Wiesław

2015-01-15

The Standard Model of strong and electroweak interactions uses point-like spin 1/2 particles as the building bricks of matter and point-like spin 1 particles as the force carriers. One of the most important questions to be answered by the present and future particle physics experiments is whether the elementary spin 0 particles exist, and if they do, what are their interactions with the spin 1/2 and spin 1 particles. Spin 0 particles have been searched extensively over the last decades. Several initial claims of their discoveries were finally disproved in the final experimental scrutiny process. The recent observation of themore » excess of events at the LHC in the final states involving a pair of vector bosons, or photons, is commonly interpreted as the discovery of the first elementary scalar particle, the Higgs boson. In this paper we recall examples of claims and subsequent disillusions in precedent searches spin 0 particles. We address the question if the LHC Higgs discovery can already be taken for granted, or, as it turned out important in the past, whether it requires a further experimental scrutiny before the existence of the first ever found elementary scalar particle is proven beyond any doubt. An example of the Double Drell–Yan process for which such a scrutiny is indispensable is discussed in some detail. - Highlights: • We present a short history of searches of spin 0 particles. • We construct a model of the Double Drell–Yan Process (DDYP) at the LHC. • We investigate the contribution of the DDYP to the Higgs searches background.« less
Nonlinear instability of half-solitons on star graphs

NASA Astrophysics Data System (ADS)

Kairzhan, Adilbek; Pelinovsky, Dmitry E.

2018-06-01

We consider a half-soliton stationary state of the nonlinear Schrödinger equation with the power nonlinearity on a star graph consisting of N edges and a single vertex. For the subcritical power nonlinearity, the half-soliton state is a degenerate critical point of the action functional under the mass constraint such that the second variation is nonnegative. By using normal forms, we prove that the degenerate critical point is a saddle point, for which the small perturbations to the half-soliton state grow slowly in time resulting in the nonlinear instability of the half-soliton state. The result holds for any N ≥ 3 and arbitrary subcritical power nonlinearity. It gives a precise dynamical characterization of the previous result of Adami et al. (2012) [2], where the half-soliton state was shown to be a saddle point of the action functional under the mass constraint for N = 3 and for cubic nonlinearity.
Solving the ecological puzzle of mycorrhizal associations using data from annotated collections and environmental samples - an example of saddle fungi.

PubMed

Hwang, Jonathan; Zhao, Qi; Yang, Zhu L; Wang, Zheng; Townsend, Jeffrey P

2015-08-01

The relation between ecological and genetic divergence of Helvella species (saddle fungi) has been perplexing. While a few species have been clearly demonstrated to be ectomycorrhizal fungi, ecological roles of many other species have been controversial, alternately considered as either saprotrophic or mycorrhizal. We applied SATé to build an inclusive deoxyribonucleic acid sequence alignment for the internal transcribed spacers (ITS) of annotated Helvella species and related environmental sequences. Phylogenetic informativeness of ITS and its regions were assessed using PhyDesign. Mycorrhizal lineages present a diversity of ecology, host type and geographic distribution. In two Helvella clades, no Helvella ITS sequences were recovered from root tips. Inclusion of environmental sequences in the ITS phylogeny from these sequences has the potential to link these data and reveal Helvella ecology. This study can serve as a model for revealing the diversity of relationships between unculturable fungi and their potential plant hosts. How non-mycorrhizal life styles within Helvella evolved will require expanded metagenomic investigation of soil and other environmental samples along with study of Helvella genomes. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.
Exploration Opportunity Search of Near-earth Objects Based on Analytical Gradients

NASA Astrophysics Data System (ADS)

Ren, Yuan; Cui, Ping-Yuan; Luan, En-Jie

2008-07-01

The problem of search of opportunity for the exploration of near-earth minor objects is investigated. For rendezvous missions, the analytical gradients of the performance index with respect to the free parameters are derived using the variational calculus and the theory of state-transition matrix. After generating randomly some initial guesses in the search space, the performance index is optimized, guided by the analytical gradients, leading to the local minimum points representing the potential launch opportunities. This method not only keeps the global-search property of the traditional method, but also avoids the blindness in the latter, thereby increasing greatly the computing speed. Furthermore, with this method, the searching precision could be controlled effectively.
A fast image matching algorithm based on key points

NASA Astrophysics Data System (ADS)

Wang, Huilin; Wang, Ying; An, Ru; Yan, Peng

2014-05-01

Image matching is a very important technique in image processing. It has been widely used for object recognition and tracking, image retrieval, three-dimensional vision, change detection, aircraft position estimation, and multi-image registration. Based on the requirements of matching algorithm for craft navigation, such as speed, accuracy and adaptability, a fast key point image matching method is investigated and developed. The main research tasks includes: (1) Developing an improved celerity key point detection approach using self-adapting threshold of Features from Accelerated Segment Test (FAST). A method of calculating self-adapting threshold was introduced for images with different contrast. Hessian matrix was adopted to eliminate insecure edge points in order to obtain key points with higher stability. This approach in detecting key points has characteristics of small amount of computation, high positioning accuracy and strong anti-noise ability; (2) PCA-SIFT is utilized to describe key point. 128 dimensional vector are formed based on the SIFT method for the key points extracted. A low dimensional feature space was established by eigenvectors of all the key points, and each eigenvector was projected onto the feature space to form a low dimensional eigenvector. These key points were re-described by dimension-reduced eigenvectors. After reducing the dimension by the PCA, the descriptor was reduced to 20 dimensions from the original 128. This method can reduce dimensions of searching approximately near neighbors thereby increasing overall speed; (3) Distance ratio between the nearest neighbour and second nearest neighbour searching is regarded as the measurement criterion for initial matching points from which the original point pairs matched are obtained. Based on the analysis of the common methods (e.g. RANSAC (random sample consensus) and Hough transform cluster) used for elimination false matching point pairs, a heuristic local geometric restriction
Improvement of correlation-based centroiding methods for point source Shack-Hartmann wavefront sensor

NASA Astrophysics Data System (ADS)

Li, Xuxu; Li, Xinyang; wang, Caixia

2018-03-01

This paper proposes an efficient approach to decrease the computational costs of correlation-based centroiding methods used for point source Shack-Hartmann wavefront sensors. Four typical similarity functions have been compared, i.e. the absolute difference function (ADF), ADF square (ADF2), square difference function (SDF), and cross-correlation function (CCF) using the Gaussian spot model. By combining them with fast search algorithms, such as three-step search (TSS), two-dimensional logarithmic search (TDL), cross search (CS), and orthogonal search (OS), computational costs can be reduced drastically without affecting the accuracy of centroid detection. Specifically, OS reduces calculation consumption by 90%. A comprehensive simulation indicates that CCF exhibits a better performance than other functions under various light-level conditions. Besides, the effectiveness of fast search algorithms has been verified.
In Search of Speedier Searches.

ERIC Educational Resources Information Center

Peterson, Ivars

1984-01-01

Methods to make computer searching as simple and efficient as possible have led to the development of various data structures. Data structures specify the items involved in searching and what can be done to them. The nature and advantages of using "self-adjusting" data structures (self-adjusting binary search trees) are discussed. (JN)
Automatic extraction of protein point mutations using a graph bigram association.

PubMed

Lee, Lawrence C; Horn, Florence; Cohen, Fred E

2007-02-02

Protein point mutations are an essential component of the evolutionary and experimental analysis of protein structure and function. While many manually curated databases attempt to index point mutations, most experimentally generated point mutations and the biological impacts of the changes are described in the peer-reviewed published literature. We describe an application, Mutation GraB (Graph Bigram), that identifies, extracts, and verifies point mutations from biomedical literature. The principal problem of point mutation extraction is to link the point mutation with its associated protein and organism of origin. Our algorithm uses a graph-based bigram traversal to identify these relevant associations and exploits the Swiss-Prot protein database to verify this information. The graph bigram method is different from other models for point mutation extraction in that it incorporates frequency and positional data of all terms in an article to drive the point mutation-protein association. Our method was tested on 589 articles describing point mutations from the G protein-coupled receptor (GPCR), tyrosine kinase, and ion channel protein families. We evaluated our graph bigram metric against a word-proximity metric for term association on datasets of full-text literature in these three different protein families. Our testing shows that the graph bigram metric achieves a higher F-measure for the GPCRs (0.79 versus 0.76), protein tyrosine kinases (0.72 versus 0.69), and ion channel transporters (0.76 versus 0.74). Importantly, in situations where more than one protein can be assigned to a point mutation and disambiguation is required, the graph bigram metric achieves a precision of 0.84 compared with the word distance metric precision of 0.73. We believe the graph bigram search metric to be a significant improvement over previous search metrics for point mutation extraction and to be applicable to text-mining application requiring the association of words.
Evaluating a Federated Medical Search Engine

PubMed Central

Belden, J.; Williams, J.; Richardson, B.; Schuster, K.

2014-01-01

Summary Background Federated medical search engines are health information systems that provide a single access point to different types of information. Their efficiency as clinical decision support tools has been demonstrated through numerous evaluations. Despite their rigor, very few of these studies report holistic evaluations of medical search engines and even fewer base their evaluations on existing evaluation frameworks. Objectives To evaluate a federated medical search engine, MedSocket, for its potential net benefits in an established clinical setting. Methods This study applied the Human, Organization, and Technology (HOT-fit) evaluation framework in order to evaluate MedSocket. The hierarchical structure of the HOT-factors allowed for identification of a combination of efficiency metrics. Human fit was evaluated through user satisfaction and patterns of system use; technology fit was evaluated through the measurements of time-on-task and the accuracy of the found answers; and organization fit was evaluated from the perspective of system fit to the existing organizational structure. Results Evaluations produced mixed results and suggested several opportunities for system improvement. On average, participants were satisfied with MedSocket searches and confident in the accuracy of retrieved answers. However, MedSocket did not meet participants’ expectations in terms of download speed, access to information, and relevance of the search results. These mixed results made it necessary to conclude that in the case of MedSocket, technology fit had a significant influence on the human and organization fit. Hence, improving technological capabilities of the system is critical before its net benefits can become noticeable. Conclusions The HOT-fit evaluation framework was instrumental in tailoring the methodology for conducting a comprehensive evaluation of the search engine. Such multidimensional evaluation of the search engine resulted in recommendations for
Cosmological viability conditions for f(T) dark energy models

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

Setare, M.R.; Mohammadipour, N., E-mail: rezakord@ipm.ir, E-mail: N.Mohammadipour@uok.ac.ir

2012-11-01

Recently f(T) modified teleparallel gravity where T is the torsion scalar has been proposed as the natural gravitational alternative for dark energy. We perform a detailed dynamical analysis of these models and find conditions for the cosmological viability of f(T) dark energy models as geometrical constraints on the derivatives of these models. We show that in the phase space exists two cosmologically viable trajectory which (i) The universe would start from an unstable radiation point, then pass a saddle standard matter point which is followed by accelerated expansion de sitter point. (ii) The universe starts from a saddle radiation epoch,more » then falls onto the stable matter era and the system can not evolve to the dark energy dominated epoch. Finally, for a number of f(T) dark energy models were proposed in the more literature, the viability conditions are investigated.« less
`Googling' Terrorists: Are Northern Irish Terrorists Visible on Internet Search Engines?

NASA Astrophysics Data System (ADS)

Reilly, P.

In this chapter, the analysis suggests that Northern Irish terrorists are not visible on Web search engines when net users employ conventional Internet search techniques. Editors of mass media organisations traditionally have had the ability to decide whether a terrorist atrocity is `newsworthy,' controlling the `oxygen' supply that sustains all forms of terrorism. This process, also known as `gatekeeping,' is often influenced by the norms of social responsibility, or alternatively, with regard to the interests of the advertisers and corporate sponsors that sustain mass media organisations. The analysis presented in this chapter suggests that Internet search engines can also be characterised as `gatekeepers,' albeit without the ability to shape the content of Websites before it reaches net users. Instead, Internet search engines give priority retrieval to certain Websites within their directory, pointing net users towards these Websites rather than others on the Internet. Net users are more likely to click on links to the more `visible' Websites on Internet search engine directories, these sites invariably being the highest `ranked' in response to a particular search query. A number of factors including the design of the Website and the number of links to external sites determine the `visibility' of a Website on Internet search engines. The study suggests that Northern Irish terrorists and their sympathisers are unlikely to achieve a greater degree of `visibility' online than they enjoy in the conventional mass media through the perpetration of atrocities. Although these groups may have a greater degree of freedom on the Internet to publicise their ideologies, they are still likely to be speaking to the converted or members of the press. Although it is easier to locate Northern Irish terrorist organisations on Internet search engines by linking in via ideology, ideological description searches, such as `Irish Republican' and `Ulster Loyalist,' are more likely to
Using Gaussian windows to explore a multivariate data set

NASA Technical Reports Server (NTRS)

Jaeckel, Louis A.

1991-01-01

In an earlier paper, I recounted an exploratory analysis, using Gaussian windows, of a data set derived from the Infrared Astronomical Satellite. Here, my goals are to develop strategies for finding structural features in a data set in a many-dimensional space, and to find ways to describe the shape of such a data set. After a brief review of Gaussian windows, I describe the current implementation of the method. I give some ways of describing features that we might find in the data, such as clusters and saddle points, and also extended structures such as a 'bar', which is an essentially one-dimensional concentration of data points. I then define a distance function, which I use to determine which data points are 'associated' with a feature. Data points not associated with any feature are called 'outliers'. I then explore the data set, giving the strategies that I used and quantitative descriptions of the features that I found, including clusters, bars, and a saddle point. I tried to use strategies and procedures that could, in principle, be used in any number of dimensions.
Potential surfaces for O atom-polymer reactions

NASA Technical Reports Server (NTRS)

Laskowski, B. C.; Jaffe, R. L.

1987-01-01

Ab initio quantum chemistry methods are used to study the energetics of interactions of O atoms with organic compounds. Polyethylene (CH2)n has been chosen as the model system to study the interactions of O(3P) and O(1D) atoms with polymers. In particular, H abstraction is investigated and polyethylene is represented by a C3 (propane) oligomeric model. The gradient method, as implemented in the GRADSCF package of programs, is used to determine the geometries and energies of products and reactants. The saddle point, barrier geometry is determined by minimizing the squares of the gradients of the potential with respect to the internal coordinates. To correctly describe the change in bonding during the reaction at least a two configuration MCSCF (multiconfiguration self consistent field) or GVB (generalized valence bond) wave function has to be used. Basis sets include standard Pople and Dunning sets, however, increased with polarization functions and diffuse p functions on both the C and O atoms. The latter is important due to the O(-) character of the wave function at the saddle point and products. Normal modes and vibrational energy levels are given for the reactants, saddle points and products. Finally, quantitative energetics are obtained by implementing a small CAS (complete active space) approach followed by limited configuration interaction (CI) calculations. Comparisons are made with available experimental data.
A Search Technique for Weak and Long-Duration Gamma-Ray Bursts from Background Model Residuals

NASA Technical Reports Server (NTRS)

Skelton, R. T.; Mahoney, W. A.

1993-01-01

We report on a planned search technique for Gamma-Ray Bursts too weak to trigger the on-board threshold. The technique is to search residuals from a physically based background model used for analysis of point sources by the Earth occultation method.

Distractor ratio and grouping processes in visual conjunction search.

PubMed

Poisson, M E; Wilkinson, F

1992-01-01

According to feature integration theory, conjunction search is conducted via a serial self-terminating search. However, effects attributed to search processes operating on the entire display may actually reflect search restricted to elements defined by a single feature. In experiment 1 this question is addressed in a reaction-time (RT) paradigm by varying distractor ratios within an array of fixed size. For trials in which the target was present in the array, RT functions were roughly symmetric, the shortest RTs being for extreme distractor ratios, and the longest RTs being for arrays in which there were an equal number of each distractor type. This result is superficially consistent with Zohary and Hochstein's interpretation that subjects search for only one distractor type and are able to switch search strategy from trial to trial. However, negative-trial data from experiment 1 case doubt on this interpretation. In experiment 2 the possible role of 'pop out' and of distractor grouping in visual conjunction search is investigated. Results of experiment 2 suggest that grouping may play a more important role than does distractor ratio, and point to the importance of the spatial layout of the target and of the distractor elements in visual conjunction search. Results of experiment 2 also provide clear evidence that groups of spatially adjacent homogeneous elements may be processed as a unit.
Boundary stress tensor and asymptotically AdS3 non-Einstein spaces at the chiral point

NASA Astrophysics Data System (ADS)

Giribet, Gaston; Goya, Andrés; Leston, Mauricio

2011-09-01

Chiral gravity admits asymptotically AdS3 solutions that are not locally equivalent to AdS3; meaning that solutions do exist which, while obeying the strong boundary conditions usually imposed in general relativity, happen not to be Einstein spaces. In topologically massive gravity (TMG), the existence of non-Einstein solutions is particularly connected to the question about the role played by complex saddle points in the Euclidean path integral. Consequently, studying (the existence of) nonlocally AdS3 solutions to chiral gravity is relevant to understanding the quantum theory. Here, we discuss a special family of nonlocally AdS3 solutions to chiral gravity. In particular, we show that such solutions persist when one deforms the theory by adding the higher-curvature terms of the so-called new massive gravity. Moreover, the addition of higher-curvature terms to the gravity action introduces new nonlocally AdS3 solutions that have no analogues in TMG. Both stationary and time-dependent, axially symmetric solutions that asymptote AdS3 space without being locally equivalent to it appear. Defining the boundary stress tensor for the full theory, we show that these non-Einstein geometries have associated vanishing conserved charges.
Efficient search of multiple types of targets

NASA Astrophysics Data System (ADS)

Wosniack, M. E.; Raposo, E. P.; Viswanathan, G. M.; da Luz, M. G. E.

2015-12-01

Random searches often take place in fragmented landscapes. Also, in many instances like animal foraging, significant benefits to the searcher arise from visits to a large diversity of patches with a well-balanced distribution of targets found. Up to date, such aspects have been widely ignored in the usual single-objective analysis of search efficiency, in which one seeks to maximize just the number of targets found per distance traversed. Here we address the problem of determining the best strategies for the random search when these multiple-objective factors play a key role in the process. We consider a figure of merit (efficiency function), which properly "scores" the mentioned tasks. By considering random walk searchers with a power-law asymptotic Lévy distribution of step lengths, p (ℓ ) ˜ℓ-μ , with 1 <μ ≤3 , we show that the standard optimal strategy with μopt≈2 no longer holds universally. Instead, optimal searches with enhanced superdiffusivity emerge, including values as low as μopt≈1.3 (i.e., tending to the ballistic limit). For the general theory of random search optimization, our findings emphasize the necessity to correctly characterize the multitude of aims in any concrete metric to compare among possible candidates to efficient strategies. In the context of animal foraging, our results might explain some empirical data pointing to stronger superdiffusion (μ <2 ) in the search behavior of different animal species, conceivably associated to multiple goals to be achieved in fragmented landscapes.
Search for cosmic ray sources using muons detected by the MACRO experiment

NASA Astrophysics Data System (ADS)

Ambrosio, M.; Antolini, R.; Auriemma, G.; Bakari, D.; Baldini, A.; Barbarino, G. C.; Barish, B. C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bloise, C.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Caruso, R.; Cecchini, S.; Cei, F.; Chiarella, V.; Choudhary, B. C.; Coutu, S.; Cozzi, M.; de Cataldo, G.; Dekhissi, H.; de Marzo, C.; de Mitri, I.; Derkaoui, J.; de Vincenzi, M.; di Credico, A.; Erriquez, O.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Grillo, A.; Guarino, F.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Iarocci, E.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D. S.; Lipari, P.; Longley, N. P.; Longo, M. J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M. N.; Michael, D. G.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolò, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patera, V.; Patrizii, L.; Pazzi, R.; Peck, C. W.; Perrone, L.; Petrera, S.; Pistilli, P.; Popa, V.; Rainò, A.; Reynoldson, J.; Ronga, F.; Rrhioua, A.; Satriano, C.; Scapparone, E.; Scholberg, K.; Sciubba, A.; Serra, P.; Sioli, M.; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J. L.; Sulak, L. R.; Surdo, A.; Tarlè, G.; Togo, V.; Vakili, M.; Walter, C. W.; Webb, R.

2003-03-01

The MACRO underground detector at Gran Sasso Laboratory recorded 60 million secondary cosmic ray muons from February 1989 until December 2000. Different techniques were used to analyze this sample in search for density excesses from astrophysical point-like sources. No evidence for DC excesses for any source in an all-sky survey is reported. In addition, searches for muon excess correlated with the known binary periods of Cygnus X-3 and Hercules X-1, and searches for statistically significant bursting episodes from known γ-ray sources are also proved negative.
WCSTools 3.0: More Tools for Image Astrometry and Catalog Searching

NASA Astrophysics Data System (ADS)

Mink, Douglas J.

For five years, WCSTools has provided image astrometry for astronomers who need accurate positions for objects they wish to observe. Other functions have been added and improved since the package was first released. Support has been added for new catalogs, such as the GSC-ACT, 2MASS Point Source Catalog, and GSC II, as they have been published. A simple command line interface can search any supported catalog, returning information in several standard formats, whether the catalog is on a local disk or searchable over the World Wide Web. The catalog searching routine can be located on either end (or both ends!) of such a web connection, and the output from one catalog search can be used as the input to another search.
Interrupted Visual Searches Reveal Volatile Search Memory

ERIC Educational Resources Information Center

Shen, Y. Jeremy; Jiang, Yuhong V.

2006-01-01

This study investigated memory from interrupted visual searches. Participants conducted a change detection search task on polygons overlaid on scenes. Search was interrupted by various disruptions, including unfilled delay, passive viewing of other scenes, and additional search on new displays. Results showed that performance was unaffected by…
Interest point detection for hyperspectral imagery

NASA Astrophysics Data System (ADS)

Dorado-Muñoz, Leidy P.; Vélez-Reyes, Miguel; Roysam, Badrinath; Mukherjee, Amit

2009-05-01

This paper presents an algorithm for automated extraction of interest points (IPs)in multispectral and hyperspectral images. Interest points are features of the image that capture information from its neighbours and they are distinctive and stable under transformations such as translation and rotation. Interest-point operators for monochromatic images were proposed more than a decade ago and have since been studied extensively. IPs have been applied to diverse problems in computer vision, including image matching, recognition, registration, 3D reconstruction, change detection, and content-based image retrieval. Interest points are helpful in data reduction, and reduce the computational burden of various algorithms (like registration, object detection, 3D reconstruction etc) by replacing an exhaustive search over the entire image domain by a probe into a concise set of highly informative points. An interest operator seeks out points in an image that are structurally distinct, invariant to imaging conditions, stable under geometric transformation, and interpretable which are good candidates for interest points. Our approach extends ideas from Lowe's keypoint operator that uses local extrema of Difference of Gaussian (DoG) operator at multiple scales to detect interest point in gray level images. The proposed approach extends Lowe's method by direct conversion of scalar operations such as scale-space generation, and extreme point detection into operations that take the vector nature of the image into consideration. Experimental results with RGB and hyperspectral images which demonstrate the potential of the method for this application and the potential improvements of a fully vectorial approach over band-by-band approaches described in the literature.
Three-dimensional separation and reattachment

NASA Technical Reports Server (NTRS)

Peake, D. J.; Tobak, M.

1982-01-01

The separation of three dimensional turbulent boundary layers from the lee of flight vehicles at high angles of attack is investigated. The separation results in dominant, large scale, coiled vortex motions that pass along the body in the general direction of the free stream. In all cases of three dimensional flow separation and reattachment, the assumption of continuous vector fields of skin friction lines and external flow streamlines, coupled with simple laws of topology, provides a flow grammar whose elemental constituents are the singular points: the nodes, spiral nodes (foci), and saddles. The phenomenon of three dimensional separation may be construed as either a local or a global event, depending on whether the skin friction line that becomes a line of separation originates at a node or a saddle point.
ROC curves predicted by a model of visual search.

PubMed

Chakraborty, D P

2006-07-21

In imaging tasks where the observer is uncertain whether lesions are present, and where they could be present, the image is searched for lesions. In the free-response paradigm, which closely reflects this task, the observer provides data in the form of a variable number of mark-rating pairs per image. In a companion paper a statistical model of visual search has been proposed that has parameters characterizing the perceived lesion signal-to-noise ratio, the ability of the observer to avoid marking non-lesion locations, and the ability of the observer to find lesions. The aim of this work is to relate the search model parameters to receiver operating characteristic (ROC) curves that would result if the observer reported the rating of the most suspicious finding on an image as the overall rating. Also presented are the probability density functions (pdfs) of the underlying latent decision variables corresponding to the highest rating for normal and abnormal images. The search-model-predicted ROC curves are 'proper' in the sense of never crossing the chance diagonal and the slope is monotonically changing. They also have the interesting property of not allowing the observer to move the operating point continuously from the origin to (1, 1). For certain choices of parameters the operating points are predicted to be clustered near the initial steep region of the curve, as has been observed by other investigators. The pdfs are non-Gaussians, markedly so for the abnormal images and for certain choices of parameter values, and provide an explanation for the well-known observation that experimental ROC data generally imply a wider pdf for abnormal images than for normal images. Some features of search-model-predicted ROC curves and pdfs resemble those predicted by the contaminated binormal model, but there are significant differences. The search model appears to provide physical explanations for several aspects of experimental ROC curves.
Proton-coupled electron-transfer reduction of dioxygen catalyzed by a saddle-distorted cobalt phthalocyanine.

PubMed

Honda, Tatsuhiko; Kojima, Takahiko; Fukuzumi, Shunichi

2012-03-07

Proton-coupled electron-transfer reduction of dioxygen (O(2)) to afford hydrogen peroxide (H(2)O(2)) was investigated by using ferrocene derivatives as reductants and saddle-distorted (α-octaphenylphthalocyaninato)cobalt(II) (Co(II)(Ph(8)Pc)) as a catalyst under acidic conditions. The selective two-electron reduction of O(2) by dimethylferrocene (Me(2)Fc) and decamethylferrocene (Me(10)Fc) occurs to yield H(2)O(2) and the corresponding ferrocenium ions (Me(2)Fc(+) and Me(10)Fc(+), respectively). Mechanisms of the catalytic reduction of O(2) are discussed on the basis of detailed kinetics studies on the overall catalytic reactions as well as on each redox reaction in the catalytic cycle. The active species to react with O(2) in the catalytic reaction is switched from Co(II)(Ph(8)Pc) to protonated Co(I)(Ph(8)PcH), depending on the reducing ability of ferrocene derivatives employed. The protonation of Co(II)(Ph(8)Pc) inhibits the direct reduction of O(2); however, the proton-coupled electron transfer from Me(10)Fc to Co(II)(Ph(8)Pc) and the protonated [Co(II)(Ph(8)PcH)](+) occurs to produce Co(I)(Ph(8)PcH) and [Co(I)(Ph(8)PcH(2))](+), respectively, which react immediately with O(2). The rate-determining step is a proton-coupled electron-transfer reduction of O(2) by Co(II)(Ph(8)Pc) in the Co(II)(Ph(8)Pc)-catalyzed cycle with Me(2)Fc, whereas it is changed to the electron-transfer reduction of [Co(II)(Ph(8)PcH)](+) by Me(10)Fc in the Co(I)(Ph(8)PcH)-catalyzed cycle with Me(10)Fc. A single crystal of monoprotonated [Co(III)(Ph(8)Pc)](+), [Co(III)Cl(2)(Ph(8)PcH)], produced by the proton-coupled electron-transfer reduction of O(2) by Co(II)(Ph(8)Pc) with HCl, was obtained, and the crystal structure was determined in comparison with that of Co(II)(Ph(8)Pc). © 2012 American Chemical Society
The Search for Meaning in Factor Analytically Derived Dimensions.

ERIC Educational Resources Information Center

Hagekull, Berit

This paper discusses the development of instruments to measure individual differences in behavior during infancy. The Infant Temperament Questionnaire (ITQ), which was designed to measure the temperament dimensions identified by the New York Longitudinal Study (NYLS), constituted the methodological starting point in the search for a dimensional…
Comparing image search behaviour in the ARRS GoldMiner search engine and a clinical PACS/RIS.

PubMed

De-Arteaga, Maria; Eggel, Ivan; Do, Bao; Rubin, Daniel; Kahn, Charles E; Müller, Henning

2015-08-01

underrepresented, therefore RadLex was considered to be the best option for this task. The results show a surprising similarity between the usage behaviour in the two systems, but several subtle differences can also be noted. The average number of terms per query is 2.21 for GoldMiner and 2.07 for radTF, the used axes of RadLex (anatomy, pathology, findings, …) have almost the same distribution with clinical findings being the most frequent and the anatomical entity the second; also, combinations of RadLex axes are extremely similar between the two systems. Differences include a longer length of the sessions in radTF than in GoldMiner (3.4 and 1.9 queries per session on average). Several frequent search terms overlap but some strong differences exist in the details. In radTF the term "normal" is frequent, whereas in GoldMiner it is not. This makes intuitive sense, as in the literature normal cases are rarely described whereas in clinical work the comparison with normal cases is often a first step. The general similarity in many points is likely due to the fact that users of the two systems are influenced by their daily behaviour in using standard web search engines and follow this behaviour in their professional search. This means that many results and insights gained from standard web search can likely be transferred to more specialized search systems. Still, specialized log files can be used to find out more on reformulations and detailed strategies of users to find the right content. Copyright © 2015 Elsevier Inc. All rights reserved.
A universal preconditioner for simulating condensed phase materials

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

Packwood, David; Ortner, Christoph, E-mail: c.ortner@warwick.ac.uk; Kermode, James, E-mail: j.r.kermode@warwick.ac.uk

2016-04-28

We introduce a universal sparse preconditioner that accelerates geometry optimisation and saddle point search tasks that are common in the atomic scale simulation of materials. Our preconditioner is based on the neighbourhood structure and we demonstrate the gain in computational efficiency in a wide range of materials that include metals, insulators, and molecular solids. The simple structure of the preconditioner means that the gains can be realised in practice not only when using expensive electronic structure models but also for fast empirical potentials. Even for relatively small systems of a few hundred atoms, we observe speedups of a factor ofmore » two or more, and the gain grows with system size. An open source Python implementation within the Atomic Simulation Environment is available, offering interfaces to a wide range of atomistic codes.« less
Raman dispersion spectroscopy on the highly saddled nickel(II)-octaethyltetraphenylporphyrin reveals the symmetry of nonplanar distortions and the vibronic coupling strength of normal modes

NASA Astrophysics Data System (ADS)

Schweitzer-Stenner, Reinhard; Stichternath, Andreas; Dreybrodt, Wolfgang; Jentzen, Walter; Song, Xing-Zhi; Shelnutt, John A.; Nielsen, Ole Faurskov; Medforth, Craig J.; Smith, Kevin M.

1997-08-01

We have measured the polarized Raman cross sections and depolarization ratios of 16 fundamental modes of nickel octaethyltetraphenylporphyrin in a CS2 solution for 16 fundamental modes, i.e., the A1g-type vibrations ν1, ν2, ν3, ν4, ν5, and φ8, the B1g vibrations ν11 and ν14, the B2g vibrations ν28, ν29, and ν30 and the antisymmetric A2g modes ν19, ν20, ν22, and ν23 as function of the excitation wavelength. The data cover the entire resonant regions of the Q- and B-bands. They were analyzed by use of a theory which describes intra- and intermolecular coupling in terms of a time-independent nonadiabatic perturbation theory [E. Unger, U. Bobinger, W. Dreybrodt, and R. Schweitzer-Stenner, J. Phys. Chem. 97, 9956 (1993)]. This approach explicitly accounts in a self-consistent way for multimode mixing with all Raman modes investigated. The vibronic coupling parameters obtained from this procedure were then used to successfully fit the vibronic side bands of the absorption spectrum and to calculate the resonance excitation profiles in absolute units. Our results show that the porphyrin macrocycle is subject to B2u-(saddling) and B1u-(ruffling) distortions which lower its symmetry to S4. Thus, evidence is provided that the porphyrin molecule maintains the nonplanar structure of its crystal phase in an organic solvent. The vibronic coupling parameters indicate a breakdown of the four-orbital model. This notion is corroborated by (ZINDO/S) calculations which reveal that significant configurational interaction occurs between the electronic transitions into |Q>- and |1B>-states and various porphyrin→porphyrin, metal→porphyrin, and porphyrin→metal transitions. The intrastate coupling parameters are used to estimate the excited electronic states' displacements along the normal coordinates with respect to the ground state and their contributions to the reorganization energy. It turns out that the |B>-state is predominantly affected by symmetric A1g
Search for Hidden Particles: a new experiment proposal

NASA Astrophysics Data System (ADS)

De Lellis, G.

2015-08-01

Searches for new physics with accelerators are being performed at the LHC, looking for high massive particles coupled to matter with ordinary strength. We propose a new experiment meant to search for very weakly coupled particles in the few GeV mass domain. The existence of such particles, foreseen in different models beyond the Standard Model, is largely unexplored from the experimental point of view. A beam dump facility, built at CERN in the north area, using 400 GeV protons is a copious factory of charmed hadrons and it could be used to probe the existence of such particles. The beam dump is also an ideal source of tau neutrinos, the less known particle in the Standard Model. In particular, tau anti-neutrinos have not been observed so far. We therefore propose an experiment to search for hidden particles and study tau neutrino physics at the same time.
GeoSearch: a new virtual globe application for the submission, storage, and sharing of point-based ecological data

NASA Astrophysics Data System (ADS)

Cardille, J. A.; Gonzales, R.; Parrott, L.; Bai, J.

2009-12-01

How should researchers store and share data? For most of history, scientists with results and data to share have been mostly limited to books and journal articles. In recent decades, the advent of personal computers and shared data formats has made it feasible, though often cumbersome, to transfer data between individuals or among small groups. Meanwhile, the use of automatic samplers, simulation models, and other data-production techniques has increased greatly. The result is that there is more and more data to store, and a greater expectation that they will be available at the click of a button. In 10 or 20 years, will we still send emails to each other to learn about what data exist? The development and widespread familiarity with virtual globes like Google Earth and NASA WorldWind has created the potential, in just the last few years, to revolutionize the way we share data, search for and search through data, and understand the relationship between individual projects in research networks, where sharing and dissemination of knowledge is encouraged. For the last two years, we have been building the GeoSearch application, a cutting-edge online resource for the storage, sharing, search, and retrieval of data produced by research networks. Linking NASA’s WorldWind globe platform, the data browsing toolkit prefuse, and SQL databases, GeoSearch’s version 1.0 enables flexible searches and novel geovisualizations of large amounts of related scientific data. These data may be submitted to the database by individual researchers and processed by GeoSearch’s data parser. Ultimately, data from research groups gathered in a research network would be shared among users via the platform. Access is not limited to the scientists themselves; administrators can determine which data can be presented publicly and which require group membership. Under the auspices of the Canada’s Sustainable Forestry Management Network of Excellence, we have created a moderate-sized database
Abrupt Bølling warming and ice saddle collapse contributions to the Meltwater Pulse 1a rapid sea level rise: North American MWP1a Contribution

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

Gregoire, Lauren J.; Otto-Bliesner, Bette; Valdes, Paul J.

Elucidating the source(s) of Meltwater Pulse 1a, the largest rapid sea level rise caused by ice melt (14-18 m in less than 340 years, 14,600 years ago), is important for understanding mechanisms of rapid ice melt and the links with abrupt climate change. Here we quantify how much and by what mechanisms the North American ice sheet could have contributed to Meltwater Pulse 1a, by driving an ice sheet model with two transient climate simulations of the last 21,000 years. Ice sheet perturbed physics ensembles were run to account for model uncertainties, constraining ice extent and volume with reconstructions ofmore » 21,000 years ago to present. We determine that the North American ice sheet produced 3-4 m global mean sea level rise in 340 years due to the abrupt Bølling warming, but this response is amplified to 5-6 m when it triggers the ice sheet saddle collapse.« less
Abrupt Bølling warming and ice saddle collapse contributions to the Meltwater Pulse 1a rapid sea level rise: North American MWP1a Contribution

DOE PAGES

Gregoire, Lauren J.; Otto-Bliesner, Bette; Valdes, Paul J.; ...

2016-08-23

Elucidating the source(s) of Meltwater Pulse 1a, the largest rapid sea level rise caused by ice melt (14-18 m in less than 340 years, 14,600 years ago), is important for understanding mechanisms of rapid ice melt and the links with abrupt climate change. Here we quantify how much and by what mechanisms the North American ice sheet could have contributed to Meltwater Pulse 1a, by driving an ice sheet model with two transient climate simulations of the last 21,000 years. Ice sheet perturbed physics ensembles were run to account for model uncertainties, constraining ice extent and volume with reconstructions ofmore » 21,000 years ago to present. We determine that the North American ice sheet produced 3-4 m global mean sea level rise in 340 years due to the abrupt Bølling warming, but this response is amplified to 5-6 m when it triggers the ice sheet saddle collapse.« less
Branching Search

NASA Astrophysics Data System (ADS)

Eliazar, Iddo

2017-12-01

Search processes play key roles in various scientific fields. A widespread and effective search-process scheme, which we term Restart Search, is based on the following restart algorithm: i) set a timer and initiate a search task; ii) if the task was completed before the timer expired, then stop; iii) if the timer expired before the task was completed, then go back to the first step and restart the search process anew. In this paper a branching feature is added to the restart algorithm: at every transition from the algorithm's third step to its first step branching takes place, thus multiplying the search effort. This branching feature yields a search-process scheme which we term Branching Search. The running time of Branching Search is analyzed, closed-form results are established, and these results are compared to the coresponding running-time results of Restart Search.
Singularities in the lineshape of a second-order perturbed quadrupolar nucleus and their use in data fitting.

PubMed

Field, Timothy R; Bain, Alex D

2014-01-01

Even for large quadrupolar interactions, the powder spectrum of the central transition for a half-integral spin is relatively narrow, because it is unperturbed to first order. However, the second-order perturbation is still orientation dependent, so it generates a characteristic lineshape. This lineshape has both finite step discontinuities and singularities where the spectrum is infinite, in theory. The relative positions of these features are well-known and they play an important role in fitting experimental data. However, there has been relatively little discussion of how high the steps are, so we present explicit formulae for these heights. This gives a full characterization of the features in this lineshape which can lead to an analysis of the spectrum without the usual laborious powder average. The transition frequency, as a function of the orientation angles, shows critical points: maxima, minima and saddle points. The maxima and minima correspond to the step discontinuities and the saddle points generate the singularities. Near a maximum, the contours are ellipses, whose dimensions are determined by the second derivatives of the frequency with respect to the polar and azimuthal angles. The density of points is smooth as the contour levels move up and down, but then drops to zero when a maximum is passed, giving a step. The height of the step is determined by the Hessian matrix-the matrix of all partial second derivatives. The points near the poles and the saddle points require a more detailed analysis, but this can still be done analytically. The resulting formulae are then compared to numerical simulations of the lineshape. We expand this calculation to include a relatively simple case where there is chemical shielding anisotropy and use this to fit experimental (139)La spectra of La2O3. Copyright © 2014 Elsevier Inc. All rights reserved.

Using Search Engines to Investigate Shared Migraine Experiences.

PubMed

Burns, Sara M; Turner, Dana P; Sexton, Katherine E; Deng, Hao; Houle, Timothy T

2017-09-01

To investigate migraine patterns in the United States using Google search data and utilize this information to better understand societal-level trends. Additionally, we aimed to evaluate time-series relationships between migraines and social factors. Extensive research has been done on clinical factors associated with migraines, yet population-level social factors have not been widely explored. Migraine internet search data may provide insight into migraine trends beyond information that can be gleaned from other sources. In this longitudinal analysis of open access data, we performed a time-series analysis in which about 12 years of Google Trends data (January 1, 2004 to August 15, 2016) were assessed. Data points were captured at a daily level and Google's 0-100 adjusted scale was used as the primary outcome to enable the comparison of relative popularity in the migraine search term. We hypothesized that the volume of relative migraine Google searches would be affected by societal aspects such as day of the week, holidays, and novel social events. Several recurrent social factors that drive migraine searches were identified. Of these, day of the week had the most significant impact on the volume of Google migraine searches. On average, Mondays accumulated 13.31 higher relative search volume than Fridays (95% CI: 11.12-15.51, P ≤ .001). Surprisingly, holidays were associated with lower relative migraine search volumes. Christmas Day had 13.84 lower relative search volumes (95% CI: 6.26-21.43, P ≤ .001) and Thanks giving had 20.18 lower relative search volumes (95% CI: 12.55-27.82, P ≤ .001) than days that were not holidays. Certain novel social events and extreme weather also appear to be associated with relative migraine Google search volume. Social factors play a crucial role in explaining population level migraine patterns, and thus, warrant further exploration. © 2017 American Headache Society.
Reflections on searching for a postdoctoral position: three points to ponder.

PubMed

Jeang, Kuan-Teh

2011-09-01

Choosing the right laboratory in which to do postdoctoral training is perhaps one of the most important decisions that a scientist makes in his or her career. Does one choose a laboratory based on the research topic or the research style of the mentor? Does one choose a large laboratory or a small one? How does one fit the selection of a postdoctoral laboratory into the context of one's long-range career goals? Here, I briefly discuss three points worth considering in seeking a research laboratory for postdoctoral training after the completion of a graduate degree. Copyright © 2011.
Turning the LHC ring into a new physics search machine

NASA Astrophysics Data System (ADS)

Orava, Risto

2017-03-01

The LHC Collider Ring is proposed to be turned into an ultimate automatic search engine for new physics in four consecutive phases: (1) Searches for heavy particles produced in Central Exclusive Process (CEP): pp → p + X + p based on the existing Beam Loss Monitoring (BLM) system of the LHC; (2) Feasibility study of using the LHC Ring as a gravitation wave antenna; (3) Extensions to the current BLM system to facilitate precise registration of the selected CEP proton exit points from the LHC beam vacuum chamber; (4) Integration of the BLM based event tagging system together with the trigger/data acquisition systems of the LHC experiments to facilitate an on-line automatic search machine for the physics of tomorrow.
Periodicity and Chaos Amidst Twisting and Folding in Two-Dimensional Maps

NASA Astrophysics Data System (ADS)

Garst, Swier; Sterk, Alef E.

We study the dynamics of three planar, noninvertible maps which rotate and fold the plane. Two maps are inspired by real-world applications whereas the third map is constructed to serve as a toy model for the other two maps. The dynamics of the three maps are remarkably similar. A stable fixed point bifurcates through a Hopf-Neĭmark-Sacker which leads to a countably infinite set of resonance tongues in the parameter plane of the map. Within a resonance tongue a periodic point can bifurcate through a period-doubling cascade. At the end of the cascade we detect Hénon-like attractors which are conjectured to be the closure of the unstable manifold of a saddle periodic point. These attractors have a folded structure which can be explained by means of the concept of critical lines. We also detect snap-back repellers which can either coexist with Hénon-like attractors or which can be formed when the saddle-point of a Hénon-like attractor becomes a source.
The accuracy of Internet search engines to predict diagnoses from symptoms can be assessed with a validated scoring system.

PubMed

Shenker, Bennett S

2014-02-01

To validate a scoring system that evaluates the ability of Internet search engines to correctly predict diagnoses when symptoms are used as search terms. We developed a five point scoring system to evaluate the diagnostic accuracy of Internet search engines. We identified twenty diagnoses common to a primary care setting to validate the scoring system. One investigator entered the symptoms for each diagnosis into three Internet search engines (Google, Bing, and Ask) and saved the first five webpages from each search. Other investigators reviewed the webpages and assigned a diagnostic accuracy score. They rescored a random sample of webpages two weeks later. To validate the five point scoring system, we calculated convergent validity and test-retest reliability using Kendall's W and Spearman's rho, respectively. We used the Kruskal-Wallis test to look for differences in accuracy scores for the three Internet search engines. A total of 600 webpages were reviewed. Kendall's W for the raters was 0.71 (p<0.0001). Spearman's rho for test-retest reliability was 0.72 (p<0.0001). There was no difference in scores based on Internet search engine. We found a significant difference in scores based on the webpage's order on the Internet search engine webpage (p=0.007). Pairwise comparisons revealed higher scores in the first webpages vs. the fourth (corr p=0.009) and fifth (corr p=0.017). However, this significance was lost when creating composite scores. The five point scoring system to assess diagnostic accuracy of Internet search engines is a valid and reliable instrument. The scoring system may be used in future Internet research. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
Initial Results of a Survey of Earth's L4 Point for Possible Earth Trojan Asteroids

NASA Astrophysics Data System (ADS)

Connors, M.; Veillet, C.; Wiegert, P.; Innanen, K.; Mikkola, S.

2000-10-01

Using the Canada-France-Hawaii 3.6 m telescope and the new CFH12k wide-field CCD imager, a survey of the region near Earth's L4 (morning) Lagrange Point was conducted in May and July/August 2000, in hopes of finding asteroids at or near this point. This survey was motivated by the dynamical interest of a possible Earth Trojan asteroid (ETA) population and by the fact that they would be the easiest asteroids to access from Earth. Recent calculations (Wiegert, Innanen and Mikkola, 2000, Icarus v. 145, 33-43) indicate stability of objects in ETA orbits over a million year timescale and that their on-sky density would be greatest roughly five degrees sunward of the L4 position. An optimized search technique was used, with tracking at the anticipated rate of the target bodies, near real-time scanning of images, and duplication of fields to aid in detection and permit followup. Limited time is available on any given night to search near the Lagrange points, and operations must be conducted at large air mass. Approximately 9 square degrees were efficiently searched and two interesting asteroids were found, NEA 2000 PM8 and our provisionally named CFZ001. CFZ001 cannot be excluded from being an Earth Trojan although that is not the optimal solution for the short arc we observed. This object, of R magnitude 22, was easily detected, suggesting that our search technique worked well. This survey supports the earlier conclusion of Whitely and Tholen (1998, Icarus v. 136, 154-167) that a large population of several hundred meter diameter ETAs does not exist. However, our effective search technique and the discovery of two interesting asteroids suggest the value of completing the survey with approximately 10 more square degrees to be searched near L4 and a comparable search to be done at L5. Funding from Canada's NSERC and HIA and the Academic Research Fund of Athabasca University is gratefully acknowledged.
SASS: A symmetry adapted stochastic search algorithm exploiting site symmetry

NASA Astrophysics Data System (ADS)

Wheeler, Steven E.; Schleyer, Paul v. R.; Schaefer, Henry F.

2007-03-01

A simple symmetry adapted search algorithm (SASS) exploiting point group symmetry increases the efficiency of systematic explorations of complex quantum mechanical potential energy surfaces. In contrast to previously described stochastic approaches, which do not employ symmetry, candidate structures are generated within simple point groups, such as C2, Cs, and C2v. This facilitates efficient sampling of the 3N-6 Pople's dimensional configuration space and increases the speed and effectiveness of quantum chemical geometry optimizations. Pople's concept of framework groups [J. Am. Chem. Soc. 102, 4615 (1980)] is used to partition the configuration space into structures spanning all possible distributions of sets of symmetry equivalent atoms. This provides an efficient means of computing all structures of a given symmetry with minimum redundancy. This approach also is advantageous for generating initial structures for global optimizations via genetic algorithm and other stochastic global search techniques. Application of the SASS method is illustrated by locating 14 low-lying stationary points on the cc-pwCVDZ ROCCSD(T) potential energy surface of Li5H2. The global minimum structure is identified, along with many unique, nonintuitive, energetically favorable isomers.
Thin‐ or thick‐skinned faulting in the Yakima fold and thrust belt (WA)? Constraints from kinematic modeling of the saddle mountains anticline

USGS Publications Warehouse

Casale, Gabriele; Pratt, Thomas L.

2015-01-01

The Yakima fold and thrust belt (YFTB) deforms the Columbia River Basalt Group flows of Washington State. The YFTB fault geometries and slip rates are crucial parameters for seismic‐hazard assessments of nearby dams and nuclear facilities, yet there are competing models for the subsurface fault geometry involving shallowly rooted versus deeply rooted fault systems. The YFTB is also thought to be analogous to the evenly spaced wrinkle ridges found on other terrestrial planets. Using seismic reflection data, borehole logs, and surface geologic data, we tested two proposed kinematic end‐member thick‐ and thin‐skinned fault models beneath the Saddle Mountains anticline of the YFTB. Observed subsurface geometry can be produced by 600–800 m of heave along a single listric‐reverse fault or ∼3.5 km of slip along two superposed low‐angle thrust faults. Both models require decollement slip between 7 and 9 km depth, resulting in greater fault areas than sometimes assumed in hazard assessments. Both models require initial slip much earlier than previously thought and may provide insight into the subsurface geometry of analogous comparisons to wrinkle ridges observed on other planets.
Searching Lost People with Uavs: the System and Results of the Close-Search Project

NASA Astrophysics Data System (ADS)

Molina, P.; Colomina, I.; Vitoria, T.; Silva, P. F.; Skaloud, J.; Kornus, W.; Prades, R.; Aguilera, C.

2012-07-01

This paper will introduce the goals, concept and results of the project named CLOSE-SEARCH, which stands for 'Accurate and safe EGNOS-SoL Navigation for UAV-based low-cost Search-And-Rescue (SAR) operations'. The main goal is to integrate a medium-size, helicopter-type Unmanned Aerial Vehicle (UAV), a thermal imaging sensor and an EGNOS-based multi-sensor navigation system, including an Autonomous Integrity Monitoring (AIM) capability, to support search operations in difficult-to-access areas and/or night operations. The focus of the paper is three-fold. Firstly, the operational and technical challenges of the proposed approach are discussed, such as ultra-safe multi-sensor navigation system, the use of combined thermal and optical vision (infrared plus visible) for person recognition and Beyond-Line-Of-Sight communications among others. Secondly, the implementation of the integrity concept for UAV platforms is discussed herein through the AIM approach. Based on the potential of the geodetic quality analysis and on the use of the European EGNOS system as a navigation performance starting point, AIM approaches integrity from the precision standpoint; that is, the derivation of Horizontal and Vertical Protection Levels (HPLs, VPLs) from a realistic precision estimation of the position parameters is performed and compared to predefined Alert Limits (ALs). Finally, some results from the project test campaigns are described to report on particular project achievements. Together with actual Search-and-Rescue teams, the system was operated in realistic, user-chosen test scenarios. In this context, and specially focusing on the EGNOS-based UAV navigation, the AIM capability and also the RGB/thermal imaging subsystem, a summary of the results is presented.
Search for Boosted Dark Matter Interacting with Electrons in Super-Kamiokande

NASA Astrophysics Data System (ADS)

Kachulis, C.; Abe, K.; Bronner, C.; Hayato, Y.; Ikeda, M.; Iyogi, K.; Kameda, J.; Kato, Y.; Kishimoto, Y.; Marti, Ll.; Miura, M.; Moriyama, S.; Nakahata, M.; Nakano, Y.; Nakayama, S.; Okajima, Y.; Orii, A.; Pronost, G.; Sekiya, H.; Shiozawa, M.; Sonoda, Y.; Takeda, A.; Takenaka, A.; Tanaka, H.; Tasaka, S.; Tomura, T.; Akutsu, R.; Kajita, T.; Kaneyuki, K.; Nishimura, Y.; Okumura, K.; Tsui, K. M.; Labarga, L.; Fernandez, P.; Blaszczyk, F. d. M.; Gustafson, J.; Kearns, E.; Raaf, J. L.; Stone, J. L.; Sulak, L. R.; Berkman, S.; Tobayama, S.; Goldhaber, M.; Elnimr, M.; Kropp, W. R.; Mine, S.; Locke, S.; Weatherly, P.; Smy, M. B.; Sobel, H. W.; Takhistov, V.; Ganezer, K. S.; Hill, J.; Kim, J. Y.; Lim, I. T.; Park, R. G.; Himmel, A.; Li, Z.; O'Sullivan, E.; Scholberg, K.; Walter, C. W.; Ishizuka, T.; Nakamura, T.; Jang, J. S.; Choi, K.; Learned, J. G.; Matsuno, S.; Smith, S. N.; Amey, J.; Litchfield, R. P.; Ma, W. Y.; Uchida, Y.; Wascko, M. O.; Cao, S.; Friend, M.; Hasegawa, T.; Ishida, T.; Ishii, T.; Kobayashi, T.; Nakadaira, T.; Nakamura, K.; Oyama, Y.; Sakashita, K.; Sekiguchi, T.; Tsukamoto, T.; Abe, KE.; Hasegawa, M.; Suzuki, A. T.; Takeuchi, Y.; Yano, T.; Hayashino, T.; Hiraki, T.; Hirota, S.; Huang, K.; Jiang, M.; Nakamura, KE.; Nakaya, T.; Quilain, B.; Patel, N. D.; Wendell, R. A.; Anthony, L. H. V.; McCauley, N.; Pritchard, A.; Fukuda, Y.; Itow, Y.; Murase, M.; Muto, F.; Mijakowski, P.; Frankiewicz, K.; Jung, C. K.; Li, X.; Palomino, J. L.; Santucci, G.; Vilela, C.; Wilking, M. J.; Yanagisawa, C.; Ito, S.; Fukuda, D.; Ishino, H.; Kibayashi, A.; Koshio, Y.; Nagata, H.; Sakuda, M.; Xu, C.; Kuno, Y.; Wark, D.; Di Lodovico, F.; Richards, B.; Tacik, R.; Kim, S. B.; Cole, A.; Thompson, L.; Okazawa, H.; Choi, Y.; Ito, K.; Nishijima, K.; Koshiba, M.; Totsuka, Y.; Suda, Y.; Yokoyama, M.; Calland, R. G.; Hartz, M.; Martens, K.; Simpson, C.; Suzuki, Y.; Vagins, M. R.; Hamabe, D.; Kuze, M.; Yoshida, T.; Ishitsuka, M.; Martin, J. F.; Nantais, C. M.; Tanaka, H. A.; Konaka, A.; Chen, S.; Wan, L.; Zhang, Y.; Wilkes, R. J.; Minamino, A.; Super-Kamiokande Collaboration

2018-06-01

A search for boosted dark matter using 161.9 kt yr of Super-Kamiokande IV data is presented. We search for an excess of elastically scattered electrons above the atmospheric neutrino background, with a visible energy between 100 MeV and 1 TeV, pointing back to the Galactic center or the Sun. No such excess is observed. Limits on boosted dark matter event rates in multiple angular cones around the Galactic center and Sun are calculated. Limits are also calculated for a baseline model of boosted dark matter produced from cold dark matter annihilation or decay. This is the first experimental search for boosted dark matter from the Galactic center or the Sun interacting in a terrestrial detector.
Defense.gov Special Report: World War II: Turning Points

Science.gov Websites

Department of Defense Submit Search Turning points of World War II U.S. Marines rest in the field on landed several miles from his intended drop zone. Cook, 87, was among the handful of World War II -Day U.S. and Allied military veterans of World War II and contemporay warriors attended commemoration
Lagrangian statistics in weakly forced two-dimensional turbulence.

PubMed

Rivera, Michael K; Ecke, Robert E

2016-01-01

Measurements of Lagrangian single-point and multiple-point statistics in a quasi-two-dimensional stratified layer system are reported. The system consists of a layer of salt water over an immiscible layer of Fluorinert and is forced electromagnetically so that mean-squared vorticity is injected at a well-defined spatial scale ri. Simultaneous cascades develop in which enstrophy flows predominately to small scales whereas energy cascades, on average, to larger scales. Lagrangian correlations and one- and two-point displacements are measured for random initial conditions and for initial positions within topological centers and saddles. Some of the behavior of these quantities can be understood in terms of the trapping characteristics of long-lived centers, the slow motion near strong saddles, and the rapid fluctuations outside of either centers or saddles. We also present statistics of Lagrangian velocity fluctuations using energy spectra in frequency space and structure functions in real space. We compare with complementary Eulerian velocity statistics. We find that simultaneous inverse energy and enstrophy ranges present in spectra are not directly echoed in real-space moments of velocity difference. Nevertheless, the spectral ranges line up well with features of moment ratios, indicating that although the moments are not exhibiting unambiguous scaling, the behavior of the probability distribution functions is changing over short ranges of length scales. Implications for understanding weakly forced 2D turbulence with simultaneous inverse and direct cascades are discussed.
Eulerian and Lagrangian methods for vortex tracking in 2D and 3D flows

NASA Astrophysics Data System (ADS)

Huang, Yangzi; Green, Melissa

2014-11-01

Coherent structures are a key component of unsteady flows in shear layers. Improvement of experimental techniques has led to larger amounts of data and requires of automated procedures for vortex tracking. Many vortex criteria are Eulerian, and identify the structures by an instantaneous local swirling motion in the field, which are indicated by closed or spiral streamlines or pathlines in a reference frame. Alternatively, a Lagrangian Coherent Structures (LCS) analysis is a Lagrangian method based on the quantities calculated along fluid particle trajectories. In the current work, vortex detection is demonstrated on data from the simulation of two cases: a 2D flow with a flat plate undergoing a 45 ° pitch-up maneuver and a 3D wall-bounded turbulence channel flow. Vortices are visualized and tracked by their centers and boundaries using Γ1, the Q criterion, and LCS saddle points. In the cases of 2D flow, saddle points trace showed a rapid acceleration of the structure which indicates the shedding from the plate. For channel flow, saddle points trace shows that average structure convection speed exhibits a similar trend as a function of wall-normal distance as the mean velocity profile, and leads to statistical quantities of vortex dynamics. Dr. Jeff Eldredge and his research group at UCLA are gratefully acknowledged for sharing the database of simulation for the current research. This work was supported by the Air Force Office of Scientific Research under AFOSR Award No. FA9550-14-1-0210.
Lagrangian statistics in weakly forced two-dimensional turbulence

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

Rivera, Michael K.; Ecke, Robert E.

Measurements of Lagrangian single-point and multiple-point statistics in a quasi-two-dimensional stratified layer system are reported. The system consists of a layer of salt water over an immiscible layer of Fluorinert and is forced electromagnetically so that mean-squared vorticity is injected at a well-defined spatial scale r i. Simultaneous cascades develop in which enstrophy flows predominately to small scales whereas energy cascades, on average, to larger scales. Lagrangian correlations and one- and two-point displacements are measured for random initial conditions and for initial positions within topological centers and saddles. Some of the behavior of these quantities can be understood in termsmore » of the trapping characteristics of long-lived centers, the slow motion near strong saddles, and the rapid fluctuations outside of either centers or saddles. We also present statistics of Lagrangian velocity fluctuations using energy spectra in frequency space and structure functions in real space. We compare with complementary Eulerian velocity statistics. We find that simultaneous inverse energy and enstrophy ranges present in spectra are not directly echoed in real-space moments of velocity difference. Nevertheless, the spectral ranges line up well with features of moment ratios, indicating that although the moments are not exhibiting unambiguous scaling, the behavior of the probability distribution functions is changing over short ranges of length scales. Furthermore, implications for understanding weakly forced 2D turbulence with simultaneous inverse and direct cascades are discussed.« less
Lagrangian statistics in weakly forced two-dimensional turbulence

DOE PAGES

Rivera, Michael K.; Ecke, Robert E.

2016-01-14

Measurements of Lagrangian single-point and multiple-point statistics in a quasi-two-dimensional stratified layer system are reported. The system consists of a layer of salt water over an immiscible layer of Fluorinert and is forced electromagnetically so that mean-squared vorticity is injected at a well-defined spatial scale r i. Simultaneous cascades develop in which enstrophy flows predominately to small scales whereas energy cascades, on average, to larger scales. Lagrangian correlations and one- and two-point displacements are measured for random initial conditions and for initial positions within topological centers and saddles. Some of the behavior of these quantities can be understood in termsmore » of the trapping characteristics of long-lived centers, the slow motion near strong saddles, and the rapid fluctuations outside of either centers or saddles. We also present statistics of Lagrangian velocity fluctuations using energy spectra in frequency space and structure functions in real space. We compare with complementary Eulerian velocity statistics. We find that simultaneous inverse energy and enstrophy ranges present in spectra are not directly echoed in real-space moments of velocity difference. Nevertheless, the spectral ranges line up well with features of moment ratios, indicating that although the moments are not exhibiting unambiguous scaling, the behavior of the probability distribution functions is changing over short ranges of length scales. Furthermore, implications for understanding weakly forced 2D turbulence with simultaneous inverse and direct cascades are discussed.« less
Quality of anaesthesia-related information accessed via Internet searches.

PubMed

Caron, S; Berton, J; Beydon, L

2007-08-01

We conducted a study to examine the quality and stability of information available from the Internet on four anaesthesia-related topics. In January 2006, we searched using four key words (porphyria, scleroderma, transfusion risk, and epidural analgesia risk) with five search engines (Google, HotBot, AltaVista, Excite, and Yahoo). We used a published scoring system (NetScoring) to evaluate the first 15 sites identified by each of these 20 searches. We also used a simple four-point scale to assess the first 100 sites in the Google search on one of our four topics ('epidural analgesia risk'). In November 2006, we conducted a second evaluation, using three search engines (Google, AltaVista, and Yahoo) with 14 synonyms for 'epidural analgesia risk'. The five search engines performed similarly. NetScoring scores were lower for transfusion risk (P < 0.001). One or more high-quality sites was identified consistently among the first 15 sites in each search. Quality scored using the simple scale correlated closely with medical content and design by NetScoring and with the number of references (P < 0.05). Synonyms of 'epidural analgesia risk' yielded similar results. The quality of accessed information improved somewhat over the 11 month period with Yahoo and AltaVista, but declined with Google. The Internet is a valuable tool for obtaining medical information, but the quality of websites varies between different topics. A simple rating scale may facilitate the quality scoring on individual websites. Differences in precise search terms used for a given topic did not appear to affect the quality of the information obtained.
Optimal random search for a single hidden target.

PubMed

Snider, Joseph

2011-01-01

A single target is hidden at a location chosen from a predetermined probability distribution. Then, a searcher must find a second probability distribution from which random search points are sampled such that the target is found in the minimum number of trials. Here it will be shown that if the searcher must get very close to the target to find it, then the best search distribution is proportional to the square root of the target distribution regardless of dimension. For a Gaussian target distribution, the optimum search distribution is approximately a Gaussian with a standard deviation that varies inversely with how close the searcher must be to the target to find it. For a network where the searcher randomly samples nodes and looks for the fixed target along edges, the optimum is either to sample a node with probability proportional to the square root of the out-degree plus 1 or not to do so at all.
A series of complexes with a [Mn 8O 8] 8+ saddle-like core: Facile synthesis, crystal structure and magnetic property

NASA Astrophysics Data System (ADS)

Wang, Hui-Sheng; Ma, Cheng-Bing; Wang, Mei; Chen, Chang-Neng; Liu, Qiu-Tian

2008-03-01

Three manganese complexes formulated as [CeMn8IIIO 8(O 2CMe) 12(H 2O) 4]·4H 2O ( 1·4H 2O), [CeMn8IIIO 8(O 2CMe) 12(py) 3(H 2O)]·6.5H 2O ( 2·6.5H 2O), [CeMn8IIIO 8(O 2CMe) 12(bzd) 2(H 2O) 2]·10H 2O( 3·10H 2O) (where py = pyridine, bzd = benzimidazole), have been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction analyses. Complexes 1- 3 all consist of a central Ce 4+ ion surrounded by a nonplanar, saddle-like [Mn 8O 8] 8+ loop via eight μ 3sbnd O 2- ions, and peripheral ligation is provided by twelve acetate groups, four water molecules for complex 1, twelve acetate groups, three pyridines and one water molecule for complex 2, twelve acetate groups, two benzimidazoles and two water molecules for complex 3. Variable-temperature magnetic susceptibility measurements reveal the ground-state spin ( S) values of 8 for complexes 1 and 2, which are half of the analogous complex previously reported. An explanation for this difference is also included in the text.
Women’s bike seats: a pressing matter for competitive female cyclists

PubMed Central

Guess, Marsha K.; Partin, Sarah N.; Schrader, Steven; Lowe, Brian; LaCombe, Julie; Reutman, Susan; Wang, Andrea; Toennis, Christine; Melman, Arnold; Mikhail, Madgy; Connell, Kathleen A.

2011-01-01

Introduction There are numerous genital complaints in women cyclists, including pain, numbness and edema of pelvic floor structures. Debate ensues about the best saddle design for protection of the pelvic floor. Aim To investigate the relationships between saddle design, seat pressures and genital nerve function in female, competitive cyclists. Methods We previously compared genital sensation in healthy, premenopausal, competitive women bicyclists and runners. The 48 cyclists from our original study comprise the study group in this sub-analysis. Main Outcome Measures (1) Genital vibratory thresholds (VT) were determined using the Medoc Vibratory Sensation Analyzer 3000. (2) Saddle pressures as determined using a specially designed map sensor. Results More than half of the participants (54.8%) used traditional saddles and the remainder (45.2%), rode with cut-out saddles. On bivariate analysis, use of traditional saddles was associated with lower mean perineal saddle pressures (MPSP) than riding on cut-out saddles. Peak perineal saddle pressures (PPSP) were also lower; however, the difference did not reach statistical significance. Saddle design did not affect mean or peak total saddle pressures (MTSP, PTSP). Saddle width was significantly associated with PPSP, MTSP and PTSP, but not with MPSP. Women riding cut-out saddles had, on average, a 4 and 11 kPa increase in MPSP and PPSP, respectively, compared to women using traditional saddles (p= 0.008 and p= 0.010), after adjustment for other variables. Use of wider saddles was associated with lower PPSP and MTSP after adjustment. Although an inverse correlation was seen between saddle pressures and VTs on bivariate analysis, these differences were not significant after adjusting for age. Conclusion Cut-out and narrower saddles negatively affect saddle pressures in female cyclists. Effects of saddle design on pudendal nerve sensory function were not apparent in this cross-sectional analysis. Longitudinal studies
Women's bike seats: a pressing matter for competitive female cyclists.

PubMed

Guess, Marsha K; Partin, Sarah N; Schrader, Steven; Lowe, Brian; LaCombe, Julie; Reutman, Susan; Wang, Andrea; Toennis, Christine; Melman, Arnold; Mikhail, Madgy; Connell, Kathleen A

2011-11-01

There are numerous genital complaints in women cyclists, including pain, numbness, and edema of pelvic floor structures. Debate ensues about the best saddle design for protection of the pelvic floor. To investigate the relationships between saddle design, seat pressures, and genital nerve function in female, competitive cyclists. We previously compared genital sensation in healthy, premenopausal, competitive women bicyclists and runners. The 48 cyclists from our original study comprise the study group in this subanalysis. Main outcome measures were: (i) genital vibratory thresholds (VTs) determined using the Medoc Vibratory Sensation Analyzer 3000 and (ii) saddle pressures as determined using a specially designed map sensor. More than half of the participants (54.8%) used traditional saddles, and the remainder (45.2%) rode with cut-out saddles. On bivariate analysis, use of traditional saddles was associated with lower mean perineal saddle pressures (MPSP) than riding on cut-out saddles. Peak perineal saddle pressures (PPSP) were also lower; however, the difference did not reach statistical significance. Saddle design did not affect mean or peak total saddle pressures (MTSP, PTSP). Saddle width was significantly associated with PPSP, MTSP, and PTSP but not with MPSP. Women riding cut-out saddles had, on average, a 4 and 11 kPa increase in MPSP and PPSP, respectively, compared with women using traditional saddles (P = 0.008 and P = 0.010), after adjustment for other variables. Use of wider saddles was associated with lower PPSP and MTSP after adjustment. Although an inverse correlation was seen between saddle pressures and VTs on bivariate analysis, these differences were not significant after adjusting for age. Cut-out and narrower saddles negatively affect saddle pressures in female cyclists. Effects of saddle design on pudendal nerve sensory function were not apparent in this cross-sectional analysis. Longitudinal studies evaluating the long-term effects of

End-user search behaviors and their relationship to search effectiveness.

PubMed Central

Wildemuth, B M; Moore, M E

1995-01-01

One hundred sixty-one MEDLINE searches conducted by third-year medical students were analyzed and evaluated to determine which search moves were used, whether those individual moves were effective, and whether there was a relationship between specific search behaviors and the effectiveness of the search strategy as a whole. The typical search included fourteen search statements, used seven terms or "limit" commands, and resulted in the display of eleven citations. The most common moves were selection of a database, entering single-word terms and free-text term phrases, and combining sets of terms. Syntactic errors were also common. Overall, librarians judged the searches to be adequate, and students were quite satisfied with their own searches. However, librarians also identified many missed opportunities in the search strategies, including underutilization of the controlled vocabulary, subheadings, and synonyms for search concepts. No strong relationships were found between specific search behaviors and search effectiveness (as measured by the librarians' or students' evaluations). Implications of these findings for system design and user education are discussed. PMID:7581185
[Biomedical information on the internet using search engines. A one-year trial].

PubMed

Corrao, Salvatore; Leone, Francesco; Arnone, Sabrina

2004-01-01

The internet is a communication medium and content distributor that provide information in the general sense but it could be of great utility regarding as the search and retrieval of biomedical information. Search engines represent a great deal to rapidly find information on the net. However, we do not know whether general search engines and meta-search ones are reliable in order to find useful and validated biomedical information. The aim of our study was to verify the reproducibility of a search by key-words (pediatric or evidence) using 9 international search engines and 1 meta-search engine at the baseline and after a one year period. We analysed the first 20 citations as output of each searching. We evaluated the formal quality of Web-sites and their domain extensions. Moreover, we compared the output of each search at the start of this study and after a one year period and we considered as a criterion of reliability the number of Web-sites cited again. We found some interesting results that are reported throughout the text. Our findings point out an extreme dynamicity of the information on the Web and, for this reason, we advice a great caution when someone want to use search and meta-search engines as a tool for searching and retrieve reliable biomedical information. On the other hand, some search and meta-search engines could be very useful as a first step searching for defining better a search and, moreover, for finding institutional Web-sites too. This paper allows to know a more conscious approach to the internet biomedical information universe.
Theoretical Analysis of Local Search and Simple Evolutionary Algorithms for the Generalized Travelling Salesperson Problem.

PubMed

Pourhassan, Mojgan; Neumann, Frank

2018-06-22

The generalized travelling salesperson problem is an important NP-hard combinatorial optimization problem for which meta-heuristics, such as local search and evolutionary algorithms, have been used very successfully. Two hierarchical approaches with different neighbourhood structures, namely a Cluster-Based approach and a Node-Based approach, have been proposed by Hu and Raidl (2008) for solving this problem. In this paper, local search algorithms and simple evolutionary algorithms based on these approaches are investigated from a theoretical perspective. For local search algorithms, we point out the complementary abilities of the two approaches by presenting instances where they mutually outperform each other. Afterwards, we introduce an instance which is hard for both approaches when initialized on a particular point of the search space, but where a variable neighbourhood search combining them finds the optimal solution in polynomial time. Then we turn our attention to analysing the behaviour of simple evolutionary algorithms that use these approaches. We show that the Node-Based approach solves the hard instance of the Cluster-Based approach presented in Corus et al. (2016) in polynomial time. Furthermore, we prove an exponential lower bound on the optimization time of the Node-Based approach for a class of Euclidean instances.
Tunnel Point Cloud Filtering Method Based on Elliptic Cylindrical Model

NASA Astrophysics Data System (ADS)

Zhua, Ningning; Jiaa, Yonghong; Luo, Lun

2016-06-01

The large number of bolts and screws that attached to the subway shield ring plates, along with the great amount of accessories of metal stents and electrical equipments mounted on the tunnel walls, make the laser point cloud data include lots of non-tunnel section points (hereinafter referred to as non-points), therefore affecting the accuracy for modeling and deformation monitoring. This paper proposed a filtering method for the point cloud based on the elliptic cylindrical model. The original laser point cloud data was firstly projected onto a horizontal plane, and a searching algorithm was given to extract the edging points of both sides, which were used further to fit the tunnel central axis. Along the axis the point cloud was segmented regionally, and then fitted as smooth elliptic cylindrical surface by means of iteration. This processing enabled the automatic filtering of those inner wall non-points. Experiments of two groups showed coincident results, that the elliptic cylindrical model based method could effectively filter out the non-points, and meet the accuracy requirements for subway deformation monitoring. The method provides a new mode for the periodic monitoring of tunnel sections all-around deformation in subways routine operation and maintenance.
Search for Boosted Dark Matter Interacting with Electrons in Super-Kamiokande.

PubMed

Kachulis, C; Abe, K; Bronner, C; Hayato, Y; Ikeda, M; Iyogi, K; Kameda, J; Kato, Y; Kishimoto, Y; Marti, Ll; Miura, M; Moriyama, S; Nakahata, M; Nakano, Y; Nakayama, S; Okajima, Y; Orii, A; Pronost, G; Sekiya, H; Shiozawa, M; Sonoda, Y; Takeda, A; Takenaka, A; Tanaka, H; Tasaka, S; Tomura, T; Akutsu, R; Kajita, T; Kaneyuki, K; Nishimura, Y; Okumura, K; Tsui, K M; Labarga, L; Fernandez, P; Blaszczyk, F D M; Gustafson, J; Kearns, E; Raaf, J L; Stone, J L; Sulak, L R; Berkman, S; Tobayama, S; Goldhaber, M; Elnimr, M; Kropp, W R; Mine, S; Locke, S; Weatherly, P; Smy, M B; Sobel, H W; Takhistov, V; Ganezer, K S; Hill, J; Kim, J Y; Lim, I T; Park, R G; Himmel, A; Li, Z; O'Sullivan, E; Scholberg, K; Walter, C W; Ishizuka, T; Nakamura, T; Jang, J S; Choi, K; Learned, J G; Matsuno, S; Smith, S N; Amey, J; Litchfield, R P; Ma, W Y; Uchida, Y; Wascko, M O; Cao, S; Friend, M; Hasegawa, T; Ishida, T; Ishii, T; Kobayashi, T; Nakadaira, T; Nakamura, K; Oyama, Y; Sakashita, K; Sekiguchi, T; Tsukamoto, T; Abe, K E; Hasegawa, M; Suzuki, A T; Takeuchi, Y; Yano, T; Hayashino, T; Hiraki, T; Hirota, S; Huang, K; Jiang, M; Nakamura, K E; Nakaya, T; Quilain, B; Patel, N D; Wendell, R A; Anthony, L H V; McCauley, N; Pritchard, A; Fukuda, Y; Itow, Y; Murase, M; Muto, F; Mijakowski, P; Frankiewicz, K; Jung, C K; Li, X; Palomino, J L; Santucci, G; Vilela, C; Wilking, M J; Yanagisawa, C; Ito, S; Fukuda, D; Ishino, H; Kibayashi, A; Koshio, Y; Nagata, H; Sakuda, M; Xu, C; Kuno, Y; Wark, D; Di Lodovico, F; Richards, B; Tacik, R; Kim, S B; Cole, A; Thompson, L; Okazawa, H; Choi, Y; Ito, K; Nishijima, K; Koshiba, M; Totsuka, Y; Suda, Y; Yokoyama, M; Calland, R G; Hartz, M; Martens, K; Simpson, C; Suzuki, Y; Vagins, M R; Hamabe, D; Kuze, M; Yoshida, T; Ishitsuka, M; Martin, J F; Nantais, C M; Tanaka, H A; Konaka, A; Chen, S; Wan, L; Zhang, Y; Wilkes, R J; Minamino, A

2018-06-01

A search for boosted dark matter using 161.9 kt yr of Super-Kamiokande IV data is presented. We search for an excess of elastically scattered electrons above the atmospheric neutrino background, with a visible energy between 100 MeV and 1 TeV, pointing back to the Galactic center or the Sun. No such excess is observed. Limits on boosted dark matter event rates in multiple angular cones around the Galactic center and Sun are calculated. Limits are also calculated for a baseline model of boosted dark matter produced from cold dark matter annihilation or decay. This is the first experimental search for boosted dark matter from the Galactic center or the Sun interacting in a terrestrial detector.
Searches for sterile neutrinos with NOvA

DOE PAGES

Davies, Gavin S.; Aurisano, Adam; Kafka, Gareth K.; ...

2016-11-15

Contradictory evidence has been presented on the issue of neutrino mixing between the three known active neutrinos and light sterile neutrino species. Apparent short-baseline neutrino oscillations observed by the LSND and MiniBooNE experiments, the collective evidence of the reactor neutrino anomaly, and the gallium anomaly all point towards sterile neutrinos with mass at the 1 eV level. While these results are tantalizing, they are not conclusive as they are in tension with null results from other short-baseline experiments, and with disappearance searches in longbaseline and atmospheric experiments. The NOvA (NuMI Off-Axis v e Appearance) experiment may help clarify the situationmore » by searching for disappearance of active neutrinos from the NuMI (Neutrinos from the Main Injector) beam over a baseline of 810 km. We describe the method used by NOvA to look for oscillations into sterile neutrinos at the Far Detector (FD) through the disappearance of neutral-current (NC) neutrino events, including preliminary results of this search. In addition, the Near Detector (ND) is well suited for searching for anomalous short-baseline oscillations and probing the LSND and MiniBooNE sterile neutrino allowed regions using a variety of final states. We also present a novel method for selecting samples with high purity at the ND using convolutional neural networks. Furthermore, based on this method, the sensitivity to anomalous short-baseline nt appearance are shown, and searches for anomalous v e appearance and v μ disappearance at the NOvA ND are presented.« less
Spatial search on a two-dimensional lattice with long-range interactions

NASA Astrophysics Data System (ADS)

Osada, Tomo; Sanaka, Kaoru; Munro, William J.; Nemoto, Kae

2018-06-01

Quantum-walk-based algorithms that search a marked location among N locations on a d -dimensional lattice succeeds in time O (√{N }) for d >2 , while this is not found to be possible when d =2 . In this paper, we consider a spatial search algorithm using continuous-time quantum walk on a two-dimensional square lattice with the existence of additional long-range edges. We examined such a search on a probabilistic graph model where an edge connecting non-nearest-neighbor lattice points i and j apart by a distance |i -j | is added by probability pi j=|i-j | -α(α ≥0 ) . Through numerical analysis, we found that the search succeeds in time O (√{N }) when α ≤αc=2.4 ±0.1 . For α >2 , the expectation value of the additional long-range edges on each node scales as a constant when N →∞ , which means that search time of O (√{N }) is achieved on a graph with average degree scaling as a constant.
[Advanced online search techniques and dedicated search engines for physicians].

PubMed

Nahum, Yoav

2008-02-01

In recent years search engines have become an essential tool in the work of physicians. This article will review advanced search techniques from the world of information specialists, as well as some advanced search engine operators that may help physicians improve their online search capabilities, and maximize the yield of their searches. This article also reviews popular dedicated scientific and biomedical literature search engines.
EBM apps that help you search for answers to your clinical questions.

PubMed

Windish, Donna

2014-06-01

In the age of smartphones and tablets, it has become common place to find apps that help you do or find almost anything. The quality and breadth of medical apps has improved greatly in recent years. You can now find medical apps that recreate textbooks, search for current articles, calculate likelihood ratios and find point-of-care answers to clinical questions. This article describes and reviews apps aimed at helping clinicians search for evidence to support the practice of EBM.
Improving e-book access via a library-developed full-text search tool.

PubMed

Foust, Jill E; Bergen, Phillip; Maxeiner, Gretchen L; Pawlowski, Peter N

2007-01-01

This paper reports on the development of a tool for searching the contents of licensed full-text electronic book (e-book) collections. The Health Sciences Library System (HSLS) provides services to the University of Pittsburgh's medical programs and large academic health system. The HSLS has developed an innovative tool for federated searching of its e-book collections. Built using the XML-based Vivísimo development environment, the tool enables a user to perform a full-text search of over 2,500 titles from the library's seven most highly used e-book collections. From a single "Google-style" query, results are returned as an integrated set of links pointing directly to relevant sections of the full text. Results are also grouped into categories that enable more precise retrieval without reformulation of the search. A heuristic evaluation demonstrated the usability of the tool and a web server log analysis indicated an acceptable level of usage. Based on its success, there are plans to increase the number of online book collections searched. This library's first foray into federated searching has produced an effective tool for searching across large collections of full-text e-books and has provided a good foundation for the development of other library-based federated searching products.
Children's Search Engines from an Information Search Process Perspective.

ERIC Educational Resources Information Center

Broch, Elana

2000-01-01

Describes cognitive and affective characteristics of children and teenagers that may affect their Web searching behavior. Reviews literature on children's searching in online public access catalogs (OPACs) and using digital libraries. Profiles two Web search engines. Discusses some of the difficulties children have searching the Web, in the…
An optical search for small comets

NASA Astrophysics Data System (ADS)

Mutel, R. L.; Fix, J. D.

2000-11-01

We have conducted an extensive optical search for small comets with the characteristics proposed by Frank et al. [1986] and Frank and Sigwarth [1993, 1997]. The observations were made using the 0.5-m reflector of the Iowa Robotic Observatory between September 1998 and June 1999. The search technique consisted of tracking a fixed point in the ecliptic plane at +/-9° geocentric solar phase angle. The telescope scan rate was chosen to track objects moving prograde at 10 km s-1 relative to the Earth at a distance of 55,000 km. The camera was multiply shuttered to discriminate against trails caused by cosmic rays and sensor imperfections. Of 6143 total images, we selected 2713 which were suitable for detection of objects with a magnitude 16.5 or brighter with 120 pixel trails. The sensitivity and reliability of the visual detection scheme were determined by extensive double-blind tests using synthetic trails added to over 500 search images. After careful visual inspection of all images, we found no trials consistent with small comets. This result strongly disagrees with previous optical searches of Yeates [1989] and Frank et al. [1990], whose detection rates and magnitudes, when converted to the present search, predict 65+/-22 detections. We conclude that at 99% confidence, the number density of any prograde objects in the ecliptic plane brighter than magnitude 16.5 with speeds near 10 km s-1 have a number density less than 5% of the small-comet density derived by Frank et al. [1990]. Any object fainter than this magnitude limit with a mass corresponding to the small-comet hypothesis (M>20,000kg) must have either an implausibly low geometric albedo (p<0.01) or a density larger than that of water.
How Users Search the Library from a Single Search Box

ERIC Educational Resources Information Center

Lown, Cory; Sierra, Tito; Boyer, Josh

2013-01-01

Academic libraries are turning increasingly to unified search solutions to simplify search and discovery of library resources. Unfortunately, very little research has been published on library user search behavior in single search box environments. This study examines how users search a large public university library using a prominent, single…
The database search problem: a question of rational decision making.

PubMed

Gittelson, S; Biedermann, A; Bozza, S; Taroni, F

2012-10-10

This paper applies probability and decision theory in the graphical interface of an influence diagram to study the formal requirements of rationality which justify the individualization of a person found through a database search. The decision-theoretic part of the analysis studies the parameters that a rational decision maker would use to individualize the selected person. The modeling part (in the form of an influence diagram) clarifies the relationships between this decision and the ingredients that make up the database search problem, i.e., the results of the database search and the different pairs of propositions describing whether an individual is at the source of the crime stain. These analyses evaluate the desirability associated with the decision of 'individualizing' (and 'not individualizing'). They point out that this decision is a function of (i) the probability that the individual in question is, in fact, at the source of the crime stain (i.e., the state of nature), and (ii) the decision maker's preferences among the possible consequences of the decision (i.e., the decision maker's loss function). We discuss the relevance and argumentative implications of these insights with respect to recent comments in specialized literature, which suggest points of view that are opposed to the results of our study. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Heat Transfer Search Algorithm for Non-convex Economic Dispatch Problems

NASA Astrophysics Data System (ADS)

Hazra, Abhik; Das, Saborni; Basu, Mousumi

2018-06-01

This paper presents Heat Transfer Search (HTS) algorithm for the non-linear economic dispatch problem. HTS algorithm is based on the law of thermodynamics and heat transfer. The proficiency of the suggested technique has been disclosed on three dissimilar complicated economic dispatch problems with valve point effect; prohibited operating zone; and multiple fuels with valve point effect. Test results acquired from the suggested technique for the economic dispatch problem have been fitted to that acquired from other stated evolutionary techniques. It has been observed that the suggested HTS carry out superior solutions.
Heat Transfer Search Algorithm for Non-convex Economic Dispatch Problems

NASA Astrophysics Data System (ADS)

Hazra, Abhik; Das, Saborni; Basu, Mousumi

2018-03-01

This paper presents Heat Transfer Search (HTS) algorithm for the non-linear economic dispatch problem. HTS algorithm is based on the law of thermodynamics and heat transfer. The proficiency of the suggested technique has been disclosed on three dissimilar complicated economic dispatch problems with valve point effect; prohibited operating zone; and multiple fuels with valve point effect. Test results acquired from the suggested technique for the economic dispatch problem have been fitted to that acquired from other stated evolutionary techniques. It has been observed that the suggested HTS carry out superior solutions.
Iterative Most-Likely Point Registration (IMLP): A Robust Algorithm for Computing Optimal Shape Alignment

PubMed Central

Billings, Seth D.; Boctor, Emad M.; Taylor, Russell H.

2015-01-01

We present a probabilistic registration algorithm that robustly solves the problem of rigid-body alignment between two shapes with high accuracy, by aptly modeling measurement noise in each shape, whether isotropic or anisotropic. For point-cloud shapes, the probabilistic framework additionally enables modeling locally-linear surface regions in the vicinity of each point to further improve registration accuracy. The proposed Iterative Most-Likely Point (IMLP) algorithm is formed as a variant of the popular Iterative Closest Point (ICP) algorithm, which iterates between point-correspondence and point-registration steps. IMLP’s probabilistic framework is used to incorporate a generalized noise model into both the correspondence and the registration phases of the algorithm, hence its name as a most-likely point method rather than a closest-point method. To efficiently compute the most-likely correspondences, we devise a novel search strategy based on a principal direction (PD)-tree search. We also propose a new approach to solve the generalized total-least-squares (GTLS) sub-problem of the registration phase, wherein the point correspondences are registered under a generalized noise model. Our GTLS approach has improved accuracy, efficiency, and stability compared to prior methods presented for this problem and offers a straightforward implementation using standard least squares. We evaluate the performance of IMLP relative to a large number of prior algorithms including ICP, a robust variant on ICP, Generalized ICP (GICP), and Coherent Point Drift (CPD), as well as drawing close comparison with the prior anisotropic registration methods of GTLS-ICP and A-ICP. The performance of IMLP is shown to be superior with respect to these algorithms over a wide range of noise conditions, outliers, and misalignments using both mesh and point-cloud representations of various shapes. PMID:25748700
Search times and probability of detection in time-limited search

NASA Astrophysics Data System (ADS)

Wilson, David; Devitt, Nicole; Maurer, Tana

2005-05-01

When modeling the search and target acquisition process, probability of detection as a function of time is important to war games and physical entity simulations. Recent US Army RDECOM CERDEC Night Vision and Electronics Sensor Directorate modeling of search and detection has focused on time-limited search. Developing the relationship between detection probability and time of search as a differential equation is explored. One of the parameters in the current formula for probability of detection in time-limited search corresponds to the mean time to detect in time-unlimited search. However, the mean time to detect in time-limited search is shorter than the mean time to detect in time-unlimited search and the relationship between them is a mathematical relationship between these two mean times. This simple relationship is derived.
The influence of the alveolar ridge shape on the stress distribution in a free-end saddle removable partial denture supported by implant.

PubMed

Júnior, Manoel M; Anchieta, Rodolfo B; Rocha, Eduardo P; Pereira, João A; Archangelo, Carlos M; Freitas-Júnior, Amilcar C; Almeida, Erika O

2011-01-01

The alveolar ridge shape plays an important role in predicting the demand on the support tooth and alveolar bone in the removable partial denture (RPD) treatment. However, these data are unclear when the RPD is associated with implants. This study evaluated the influence of the alveolar ridge shape on the stress distribution of a free-end saddle RPD partially supported by implant using 2-dimensioanl finite element analysis (FEA). Four mathematical models (M) of a mandibular hemiarch simulating various alveolar ridge shapes (1-distal desceding, 2-concave, 3-horizontal and 4-distal ascending) were built. Tooth 33 was placed as the abutment. Two RPDs, one supported by tooth and fibromucosa (MB) and other one supported by tooth and implant (MC) were simulated. MA was the control (no RPD). The load (50N) were applied simultaneously on each cusp. Appropriate boundary conditions were assigned on the border of alveolar bone. Ansys 10.0 software was used to calculate the stress fields and the von Mises equivalent stress criteria (sigmavM) was applied to analyze the results. The distal ascending shape showed the highest sigmavM for cortical and medullar bone. The alveolar ridge shape had little effect on changing the sigmavM based on the same prosthesis, mainly around the abutment tooth.
On new physics searches with multidimensional differential shapes

NASA Astrophysics Data System (ADS)

Ferreira, Felipe; Fichet, Sylvain; Sanz, Veronica

2018-03-01

In the context of upcoming new physics searches at the LHC, we investigate the impact of multidimensional differential rates in typical LHC analyses. We discuss the properties of shape information, and argue that multidimensional rates bring limited information in the scope of a discovery, but can have a large impact on model discrimination. We also point out subtleties about systematic uncertainties cancellations and the Cauchy-Schwarz bound on interference terms.

Search Parameter Optimization for Discrete, Bayesian, and Continuous Search Algorithms

DTIC Science & Technology

2017-09-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS SEARCH PARAMETER OPTIMIZATION FOR DISCRETE , BAYESIAN, AND CONTINUOUS SEARCH ALGORITHMS by...to 09-22-2017 4. TITLE AND SUBTITLE SEARCH PARAMETER OPTIMIZATION FOR DISCRETE , BAYESIAN, AND CON- TINUOUS SEARCH ALGORITHMS 5. FUNDING NUMBERS 6...simple search and rescue acts to prosecuting aerial/surface/submersible targets on mission. This research looks at varying the known discrete and
Structure prediction of nanoclusters; a direct or a pre-screened search on the DFT energy landscape?

PubMed

Farrow, M R; Chow, Y; Woodley, S M

2014-10-21

The atomic structure of inorganic nanoclusters obtained via a search for low lying minima on energy landscapes, or hypersurfaces, is reported for inorganic binary compounds: zinc oxide (ZnO)n, magnesium oxide (MgO)n, cadmium selenide (CdSe)n, and potassium fluoride (KF)n, where n = 1-12 formula units. The computational cost of each search is dominated by the effort to evaluate each sample point on the energy landscape and the number of required sample points. The effect of changing the balance between these two factors on the success of the search is investigated. The choice of sample points will also affect the number of required data points and therefore the efficiency of the search. Monte Carlo based global optimisation routines (evolutionary and stochastic quenching algorithms) within a new software package, viz. Knowledge Led Master Code (KLMC), are employed to search both directly and after pre-screening on the DFT energy landscape. Pre-screening includes structural relaxation to minimise a cheaper energy function - based on interatomic potentials - and is found to improve significantly the search efficiency, and typically reduces the number of DFT calculations required to locate the local minima by more than an order of magnitude. Although the choice of functional form is important, the approach is robust to small changes to the interatomic potential parameters. The computational cost of initial DFT calculations of each structure is reduced by employing Gaussian smearing to the electronic energy levels. Larger (KF)n nanoclusters are predicted to form cuboid cuts from the rock-salt phase, but also share many structural motifs with (MgO)n for smaller clusters. The transition from 2D rings to 3D (bubble, or fullerene-like) structures occur at a larger cluster size for (ZnO)n and (CdSe)n. Differences between the HOMO and LUMO energies, for all the compounds apart from KF, are in the visible region of the optical spectrum (2-3 eV); KF lies deep in the UV region
Dual-mode nested search method for categorical uncertain multi-objective optimization

NASA Astrophysics Data System (ADS)

Tang, Long; Wang, Hu

2016-10-01

Categorical multi-objective optimization is an important issue involved in many matching design problems. Non-numerical variables and their uncertainty are the major challenges of such optimizations. Therefore, this article proposes a dual-mode nested search (DMNS) method. In the outer layer, kriging metamodels are established using standard regular simplex mapping (SRSM) from categorical candidates to numerical values. Assisted by the metamodels, a k-cluster-based intelligent sampling strategy is developed to search Pareto frontier points. The inner layer uses an interval number method to model the uncertainty of categorical candidates. To improve the efficiency, a multi-feature convergent optimization via most-promising-area stochastic search (MFCOMPASS) is proposed to determine the bounds of objectives. Finally, typical numerical examples are employed to demonstrate the effectiveness of the proposed DMNS method.
Broadcasting satellite service synthesis using gradient and cyclic coordinate search procedures

NASA Technical Reports Server (NTRS)

Reilly, C. H.; Mount-Campbell, C. A.; Gonsalvez, D. J.; Martin, C. H.; Levis, C. A.

1986-01-01

Two search techniques are considered for solving satellite synthesis problems. Neither is likely to find a globally optimal solution. In order to determine which method performs better and what factors affect their performance, an experiment is designed and the same problem is solved under a variety of starting solution configuration-algorithm combinations. Since there is no randomization in the experiment, results of practical, rather than statistical, significance are presented. Implementation of a cyclic coordinate search procedure clearly finds better synthesis solutions than implementation of a gradient search procedure does with the objective of maximizing the minimum C/I ratio computed at test points on the perimeters of the intended service areas. The length of the available orbital arc and the configuration of the starting solution are shown to affect the quality of the solutions found.
The dynamics of phase locking and points of resonance in a forced magnetic oscillator

NASA Astrophysics Data System (ADS)

Bryant, Paul; Jeffries, Carson

1987-03-01

We report data on an experimental system: a forced symmetric oscillator containing a saturable inductor with magnetic hysteresis. It displays a Hopf bifurcation to quasiperiodicity, entrainment horns, and chaos. We study in detail the bifurcations and hysteresis occurring near points of resonance (particularly “ strong resonance”) and show how the observed behavior can be understood using Arnold's theory. Much of the behavior relating to the entrainment horns is explored: period doubling and symmetry breaking bifurcations; homoclinic bifurcations; and crises and other bifurcations taking place at the horn boundaries. Important features of the behavior related to symmetry properties of the oscillator are studied and explained through the concept of a half-cycle map. The system is shown to exhibit a Hopf bifurcation from a phase-locked state to periodic “islands”, similar to those found in Hamiltonian systems. An initialization technique is used to observe the manifolds of saddle orbits and other hidden structure. An unusual differential equation model is developed which is irreversible and generates a noninvertible Poincaré map of the plane. Noninvertibility of this planar map has important effects on the behavior observed. The Poincaré map may also be approximated through experimental measurements, resulting in a planar map with parameter dependence. This model gives good correspondence with the system in a region of the parameter space.
GEMINI: a computationally-efficient search engine for large gene expression datasets.

PubMed

DeFreitas, Timothy; Saddiki, Hachem; Flaherty, Patrick

2016-02-24

Low-cost DNA sequencing allows organizations to accumulate massive amounts of genomic data and use that data to answer a diverse range of research questions. Presently, users must search for relevant genomic data using a keyword, accession number of meta-data tag. However, in this search paradigm the form of the query - a text-based string - is mismatched with the form of the target - a genomic profile. To improve access to massive genomic data resources, we have developed a fast search engine, GEMINI, that uses a genomic profile as a query to search for similar genomic profiles. GEMINI implements a nearest-neighbor search algorithm using a vantage-point tree to store a database of n profiles and in certain circumstances achieves an [Formula: see text] expected query time in the limit. We tested GEMINI on breast and ovarian cancer gene expression data from The Cancer Genome Atlas project and show that it achieves a query time that scales as the logarithm of the number of records in practice on genomic data. In a database with 10(5) samples, GEMINI identifies the nearest neighbor in 0.05 sec compared to a brute force search time of 0.6 sec. GEMINI is a fast search engine that uses a query genomic profile to search for similar profiles in a very large genomic database. It enables users to identify similar profiles independent of sample label, data origin or other meta-data information.
Search Tips

MedlinePlus

... do not need to use AND because the search engine automatically finds resources containing all of your search ... Use as a wildcard when you want the search engine to fill in the blank for you; you ...
Evidence-based Medicine Search: a customizable federated search engine.

PubMed

Bracke, Paul J; Howse, David K; Keim, Samuel M

2008-04-01

This paper reports on the development of a tool by the Arizona Health Sciences Library (AHSL) for searching clinical evidence that can be customized for different user groups. The AHSL provides services to the University of Arizona's (UA's) health sciences programs and to the University Medical Center. Librarians at AHSL collaborated with UA College of Medicine faculty to create an innovative search engine, Evidence-based Medicine (EBM) Search, that provides users with a simple search interface to EBM resources and presents results organized according to an evidence pyramid. EBM Search was developed with a web-based configuration component that allows the tool to be customized for different specialties. Informal and anecdotal feedback from physicians indicates that EBM Search is a useful tool with potential in teaching evidence-based decision making. While formal evaluation is still being planned, a tool such as EBM Search, which can be configured for specific user populations, may help lower barriers to information resources in an academic health sciences center.
Three-Point Correlations in the COBE DMR 2 Year Anisotropy Maps

NASA Technical Reports Server (NTRS)

Hinshaw, G.; Banday, A. J.; Bennett, C. L.; Gorski, K. M.; Kogut, A.

1995-01-01

We compute the three-point temperature correlation function of the COBE Differential Microwave Radiometer (DMR) 2 year sky maps to search for evidence of non-Gaussian temperature fluctuations. We detect three-point correlations in our sky with a substantially higher signal-to-noise ratio than from the first-year data. However, the magnitude of the signal is consistent with the level of cosmic variance expected from Gaussian fluctuations, even when the low-order multipole moments, up to l = 9, are filtered from the data. These results do not strongly constrain most existing models of structure formation, but the absence of intrinsic three-point correlations on large angular scales is an important consistency test for such models.
Loss surface of XOR artificial neural networks

NASA Astrophysics Data System (ADS)

Mehta, Dhagash; Zhao, Xiaojun; Bernal, Edgar A.; Wales, David J.

2018-05-01

Training an artificial neural network involves an optimization process over the landscape defined by the cost (loss) as a function of the network parameters. We explore these landscapes using optimization tools developed for potential energy landscapes in molecular science. The number of local minima and transition states (saddle points of index one), as well as the ratio of transition states to minima, grow rapidly with the number of nodes in the network. There is also a strong dependence on the regularization parameter, with the landscape becoming more convex (fewer minima) as the regularization term increases. We demonstrate that in our formulation, stationary points for networks with Nh hidden nodes, including the minimal network required to fit the XOR data, are also stationary points for networks with Nh+1 hidden nodes when all the weights involving the additional node are zero. Hence, smaller networks trained on XOR data are embedded in the landscapes of larger networks. Our results clarify certain aspects of the classification and sensitivity (to perturbations in the input data) of minima and saddle points for this system, and may provide insight into dropout and network compression.
Clinician search behaviors may be influenced by search engine design.

PubMed

Lau, Annie Y S; Coiera, Enrico; Zrimec, Tatjana; Compton, Paul

2010-06-30

Searching the Web for documents using information retrieval systems plays an important part in clinicians' practice of evidence-based medicine. While much research focuses on the design of methods to retrieve documents, there has been little examination of the way different search engine capabilities influence clinician search behaviors. Previous studies have shown that use of task-based search engines allows for faster searches with no loss of decision accuracy compared with resource-based engines. We hypothesized that changes in search behaviors may explain these differences. In all, 75 clinicians (44 doctors and 31 clinical nurse consultants) were randomized to use either a resource-based or a task-based version of a clinical information retrieval system to answer questions about 8 clinical scenarios in a controlled setting in a university computer laboratory. Clinicians using the resource-based system could select 1 of 6 resources, such as PubMed; clinicians using the task-based system could select 1 of 6 clinical tasks, such as diagnosis. Clinicians in both systems could reformulate search queries. System logs unobtrusively capturing clinicians' interactions with the systems were coded and analyzed for clinicians' search actions and query reformulation strategies. The most frequent search action of clinicians using the resource-based system was to explore a new resource with the same query, that is, these clinicians exhibited a "breadth-first" search behaviour. Of 1398 search actions, clinicians using the resource-based system conducted 401 (28.7%, 95% confidence interval [CI] 26.37-31.11) in this way. In contrast, the majority of clinicians using the task-based system exhibited a "depth-first" search behavior in which they reformulated query keywords while keeping to the same task profiles. Of 585 search actions conducted by clinicians using the task-based system, 379 (64.8%, 95% CI 60.83-68.55) were conducted in this way. This study provides evidence that
Privacy-preserving search for chemical compound databases.

PubMed

Shimizu, Kana; Nuida, Koji; Arai, Hiromi; Mitsunari, Shigeo; Attrapadung, Nuttapong; Hamada, Michiaki; Tsuda, Koji; Hirokawa, Takatsugu; Sakuma, Jun; Hanaoka, Goichiro; Asai, Kiyoshi

2015-01-01

Searching for similar compounds in a database is the most important process for in-silico drug screening. Since a query compound is an important starting point for the new drug, a query holder, who is afraid of the query being monitored by the database server, usually downloads all the records in the database and uses them in a closed network. However, a serious dilemma arises when the database holder also wants to output no information except for the search results, and such a dilemma prevents the use of many important data resources. In order to overcome this dilemma, we developed a novel cryptographic protocol that enables database searching while keeping both the query holder's privacy and database holder's privacy. Generally, the application of cryptographic techniques to practical problems is difficult because versatile techniques are computationally expensive while computationally inexpensive techniques can perform only trivial computation tasks. In this study, our protocol is successfully built only from an additive-homomorphic cryptosystem, which allows only addition performed on encrypted values but is computationally efficient compared with versatile techniques such as general purpose multi-party computation. In an experiment searching ChEMBL, which consists of more than 1,200,000 compounds, the proposed method was 36,900 times faster in CPU time and 12,000 times as efficient in communication size compared with general purpose multi-party computation. We proposed a novel privacy-preserving protocol for searching chemical compound databases. The proposed method, easily scaling for large-scale databases, may help to accelerate drug discovery research by making full use of unused but valuable data that includes sensitive information.
Privacy-preserving search for chemical compound databases

PubMed Central

2015-01-01

Background Searching for similar compounds in a database is the most important process for in-silico drug screening. Since a query compound is an important starting point for the new drug, a query holder, who is afraid of the query being monitored by the database server, usually downloads all the records in the database and uses them in a closed network. However, a serious dilemma arises when the database holder also wants to output no information except for the search results, and such a dilemma prevents the use of many important data resources. Results In order to overcome this dilemma, we developed a novel cryptographic protocol that enables database searching while keeping both the query holder's privacy and database holder's privacy. Generally, the application of cryptographic techniques to practical problems is difficult because versatile techniques are computationally expensive while computationally inexpensive techniques can perform only trivial computation tasks. In this study, our protocol is successfully built only from an additive-homomorphic cryptosystem, which allows only addition performed on encrypted values but is computationally efficient compared with versatile techniques such as general purpose multi-party computation. In an experiment searching ChEMBL, which consists of more than 1,200,000 compounds, the proposed method was 36,900 times faster in CPU time and 12,000 times as efficient in communication size compared with general purpose multi-party computation. Conclusion We proposed a novel privacy-preserving protocol for searching chemical compound databases. The proposed method, easily scaling for large-scale databases, may help to accelerate drug discovery research by making full use of unused but valuable data that includes sensitive information. PMID:26678650
a Gross Error Elimination Method for Point Cloud Data Based on Kd-Tree

NASA Astrophysics Data System (ADS)

Kang, Q.; Huang, G.; Yang, S.

2018-04-01

Point cloud data has been one type of widely used data sources in the field of remote sensing. Key steps of point cloud data's pro-processing focus on gross error elimination and quality control. Owing to the volume feature of point could data, existed gross error elimination methods need spend massive memory both in space and time. This paper employed a new method which based on Kd-tree algorithm to construct, k-nearest neighbor algorithm to search, settled appropriate threshold to determine with result turns out a judgement that whether target point is or not an outlier. Experimental results show that, our proposed algorithm will help to delete gross error in point cloud data and facilitate to decrease memory consumption, improve efficiency.
Cube search, revisited.

PubMed

Zhang, Xuetao; Huang, Jie; Yigit-Elliott, Serap; Rosenholtz, Ruth

2015-03-16

Observers can quickly search among shaded cubes for one lit from a unique direction. However, replace the cubes with similar 2-D patterns that do not appear to have a 3-D shape, and search difficulty increases. These results have challenged models of visual search and attention. We demonstrate that cube search displays differ from those with "equivalent" 2-D search items in terms of the informativeness of fairly low-level image statistics. This informativeness predicts peripheral discriminability of target-present from target-absent patches, which in turn predicts visual search performance, across a wide range of conditions. Comparing model performance on a number of classic search tasks, cube search does not appear unexpectedly easy. Easy cube search, per se, does not provide evidence for preattentive computation of 3-D scene properties. However, search asymmetries derived from rotating and/or flipping the cube search displays cannot be explained by the information in our current set of image statistics. This may merely suggest a need to modify the model's set of 2-D image statistics. Alternatively, it may be difficult cube search that provides evidence for preattentive computation of 3-D scene properties. By attributing 2-D luminance variations to a shaded 3-D shape, 3-D scene understanding may slow search for 2-D features of the target. © 2015 ARVO.
Cube search, revisited

PubMed Central

Zhang, Xuetao; Huang, Jie; Yigit-Elliott, Serap; Rosenholtz, Ruth

2015-01-01

Observers can quickly search among shaded cubes for one lit from a unique direction. However, replace the cubes with similar 2-D patterns that do not appear to have a 3-D shape, and search difficulty increases. These results have challenged models of visual search and attention. We demonstrate that cube search displays differ from those with “equivalent” 2-D search items in terms of the informativeness of fairly low-level image statistics. This informativeness predicts peripheral discriminability of target-present from target-absent patches, which in turn predicts visual search performance, across a wide range of conditions. Comparing model performance on a number of classic search tasks, cube search does not appear unexpectedly easy. Easy cube search, per se, does not provide evidence for preattentive computation of 3-D scene properties. However, search asymmetries derived from rotating and/or flipping the cube search displays cannot be explained by the information in our current set of image statistics. This may merely suggest a need to modify the model's set of 2-D image statistics. Alternatively, it may be difficult cube search that provides evidence for preattentive computation of 3-D scene properties. By attributing 2-D luminance variations to a shaded 3-D shape, 3-D scene understanding may slow search for 2-D features of the target. PMID:25780063
Google Search Tips

Science.gov Websites

with Search To search for a document, type a few descriptive words in the search box, and press the Enter key or click the search button. A results page appears with a list of documents and web pages that are related to your search terms, with the most relevant search results appearing at the top of the
Searching the ASRS Database Using QUORUM Keyword Search, Phrase Search, Phrase Generation, and Phrase Discovery

NASA Technical Reports Server (NTRS)

McGreevy, Michael W.; Connors, Mary M. (Technical Monitor)

2001-01-01

To support Search Requests and Quick Responses at the Aviation Safety Reporting System (ASRS), four new QUORUM methods have been developed: keyword search, phrase search, phrase generation, and phrase discovery. These methods build upon the core QUORUM methods of text analysis, modeling, and relevance-ranking. QUORUM keyword search retrieves ASRS incident narratives that contain one or more user-specified keywords in typical or selected contexts, and ranks the narratives on their relevance to the keywords in context. QUORUM phrase search retrieves narratives that contain one or more user-specified phrases, and ranks the narratives on their relevance to the phrases. QUORUM phrase generation produces a list of phrases from the ASRS database that contain a user-specified word or phrase. QUORUM phrase discovery finds phrases that are related to topics of interest. Phrase generation and phrase discovery are particularly useful for finding query phrases for input to QUORUM phrase search. The presentation of the new QUORUM methods includes: a brief review of the underlying core QUORUM methods; an overview of the new methods; numerous, concrete examples of ASRS database searches using the new methods; discussion of related methods; and, in the appendices, detailed descriptions of the new methods.
A Hybrid Search Algorithm for Swarm Robots Searching in an Unknown Environment

PubMed Central

Li, Shoutao; Li, Lina; Lee, Gordon; Zhang, Hao

2014-01-01

This paper proposes a novel method to improve the efficiency of a swarm of robots searching in an unknown environment. The approach focuses on the process of feeding and individual coordination characteristics inspired by the foraging behavior in nature. A predatory strategy was used for searching; hence, this hybrid approach integrated a random search technique with a dynamic particle swarm optimization (DPSO) search algorithm. If a search robot could not find any target information, it used a random search algorithm for a global search. If the robot found any target information in a region, the DPSO search algorithm was used for a local search. This particle swarm optimization search algorithm is dynamic as all the parameters in the algorithm are refreshed synchronously through a communication mechanism until the robots find the target position, after which, the robots fall back to a random searching mode. Thus, in this searching strategy, the robots alternated between two searching algorithms until the whole area was covered. During the searching process, the robots used a local communication mechanism to share map information and DPSO parameters to reduce the communication burden and overcome hardware limitations. If the search area is very large, search efficiency may be greatly reduced if only one robot searches an entire region given the limited resources available and time constraints. In this research we divided the entire search area into several subregions, selected a target utility function to determine which subregion should be initially searched and thereby reduced the residence time of the target to improve search efficiency. PMID:25386855
A hybrid search algorithm for swarm robots searching in an unknown environment.

PubMed

Li, Shoutao; Li, Lina; Lee, Gordon; Zhang, Hao

2014-01-01

This paper proposes a novel method to improve the efficiency of a swarm of robots searching in an unknown environment. The approach focuses on the process of feeding and individual coordination characteristics inspired by the foraging behavior in nature. A predatory strategy was used for searching; hence, this hybrid approach integrated a random search technique with a dynamic particle swarm optimization (DPSO) search algorithm. If a search robot could not find any target information, it used a random search algorithm for a global search. If the robot found any target information in a region, the DPSO search algorithm was used for a local search. This particle swarm optimization search algorithm is dynamic as all the parameters in the algorithm are refreshed synchronously through a communication mechanism until the robots find the target position, after which, the robots fall back to a random searching mode. Thus, in this searching strategy, the robots alternated between two searching algorithms until the whole area was covered. During the searching process, the robots used a local communication mechanism to share map information and DPSO parameters to reduce the communication burden and overcome hardware limitations. If the search area is very large, search efficiency may be greatly reduced if only one robot searches an entire region given the limited resources available and time constraints. In this research we divided the entire search area into several subregions, selected a target utility function to determine which subregion should be initially searched and thereby reduced the residence time of the target to improve search efficiency.

Improving e-book access via a library-developed full-text search tool*

PubMed Central

Foust, Jill E.; Bergen, Phillip; Maxeiner, Gretchen L.; Pawlowski, Peter N.

2007-01-01

Purpose: This paper reports on the development of a tool for searching the contents of licensed full-text electronic book (e-book) collections. Setting: The Health Sciences Library System (HSLS) provides services to the University of Pittsburgh's medical programs and large academic health system. Brief Description: The HSLS has developed an innovative tool for federated searching of its e-book collections. Built using the XML-based Vivísimo development environment, the tool enables a user to perform a full-text search of over 2,500 titles from the library's seven most highly used e-book collections. From a single “Google-style” query, results are returned as an integrated set of links pointing directly to relevant sections of the full text. Results are also grouped into categories that enable more precise retrieval without reformulation of the search. Results/Evaluation: A heuristic evaluation demonstrated the usability of the tool and a web server log analysis indicated an acceptable level of usage. Based on its success, there are plans to increase the number of online book collections searched. Conclusion: This library's first foray into federated searching has produced an effective tool for searching across large collections of full-text e-books and has provided a good foundation for the development of other library-based federated searching products. PMID:17252065
Search for Hidden Particles (SHiP): a new experiment proposal

NASA Astrophysics Data System (ADS)

De Lellis, G.

2015-06-01

Searches for new physics with accelerators are being performed at the LHC, looking for high massive particles coupled to matter with ordinary strength. We propose a new experimental facility meant to search for very weakly coupled particles in the few GeV mass domain. The existence of such particles, foreseen in different theoretical models beyond the Standard Model, is largely unexplored from the experimental point of view. A beam dump facility, built at CERN in the north area, using 400 GeV protons is a copious factory of charmed hadrons and could be used to probe the existence of such particles. The beam dump is also an ideal source of tau neutrinos, the less known particle in the Standard Model. In particular, tau anti-neutrinos have not been observed so far. We therefore propose an experiment to search for hidden particles and study tau neutrino physics at the same time.
Searches for electromagnetic signals from extraterrestrial beings

NASA Astrophysics Data System (ADS)

Zuckerman, B.

The techniques and rationale used in six radio-frequency surveys to detect possible signals from extraterrestrial beings (ETs) are reviewed. Reception attempts have been made by pointing antennas at the stars within 80 light years, toward F, G, K, andd M main sequence stars, and binary star systems with component separation less than one-third or more than three times the radius of the habitable zone around the main star. All of the searches explored narrow bandwidths, with attention given to rapid variability. Stars exhibiting variability were re-examined for longer periods, using the 21 cm bandwidth, which is not used for transmissions on earth. The best spectrum analyzer in operation for ET signal search purposes has a capacity of 200,000 channels. Further studies may be carried out at the 10 micron IR wavelength, which could detect planetary-size construction projects by ET civilizations.
A Study of Impact Point Detecting Method Based on Seismic Signal

NASA Astrophysics Data System (ADS)

Huo, Pengju; Zhang, Yu; Xu, Lina; Huang, Yong

The projectile landing position has to be determined for its recovery and range in the targeting test. In this paper, a global search method based on the velocity variance is proposed. In order to verify the applicability of this method, simulation analysis within the scope of four million square meters has been conducted in the same array structure of the commonly used linear positioning method, and MATLAB was used to compare and analyze the two methods. The compared simulation results show that the global search method based on the speed of variance has high positioning accuracy and stability, which can meet the needs of impact point location.
[Profile of a systematic search. Search areas, databases and reports].

PubMed

Korsbek, Lisa; Bendix, Ane Friis; Kidholm, Kristian

2006-04-03

Systematic literature search is a fundamental in evidence-based medicine. But systematic literature search is not yet a very well used way of retrieving evidence-based information. This article profiles a systematic literature search for evidence-based literature. It goes through the most central databases and gives an example of how to document the literature search. The article also sums up the literature search in all reviews in Ugeskrift for Laeger in the year 2004.
Evidence-based Medicine Search: a customizable federated search engine

PubMed Central

Bracke, Paul J.; Howse, David K.; Keim, Samuel M.

2008-01-01

Purpose: This paper reports on the development of a tool by the Arizona Health Sciences Library (AHSL) for searching clinical evidence that can be customized for different user groups. Brief Description: The AHSL provides services to the University of Arizona's (UA's) health sciences programs and to the University Medical Center. Librarians at AHSL collaborated with UA College of Medicine faculty to create an innovative search engine, Evidence-based Medicine (EBM) Search, that provides users with a simple search interface to EBM resources and presents results organized according to an evidence pyramid. EBM Search was developed with a web-based configuration component that allows the tool to be customized for different specialties. Outcomes/Conclusion: Informal and anecdotal feedback from physicians indicates that EBM Search is a useful tool with potential in teaching evidence-based decision making. While formal evaluation is still being planned, a tool such as EBM Search, which can be configured for specific user populations, may help lower barriers to information resources in an academic health sciences center. PMID:18379665
Asymmetry in search.

PubMed

Kaindl, H; Kainz, G; Radda, K

2001-01-01

Most of the work on search in artificial intelligence (AI) deals with one search direction only-mostly forward search-although it is known that a structural asymmetry of the search graph causes differences in the efficiency of searching in the forward or the backward direction, respectively. In the case of symmetrical graph structure, however, current theory would not predict such differences in efficiency. In several classes of job sequencing problems, we observed a phenomenon of asymmetry in search that relates to the distribution of the are costs in the search graph. This phenomenon can be utilized for improving the search efficiency by a new algorithm that automatically selects the search direction. We demonstrate fur a class of job sequencing problems that, through the utilization of this phenomenon, much more difficult problems can be solved-according to our best knowledge-than by the best published approach, and on the same problems, the running time is much reduced. As a consequence, we propose to check given problems for asymmetrical distribution of are costs that may cause asymmetry in search.
Age differences in visual search for compound patterns: long- versus short-range grouping.

PubMed

Burack, J A; Enns, J T; Iarocci, G; Randolph, B

2000-11-01

Visual search for compound patterns was examined in observers aged 6, 8, 10, and 22 years. The main question was whether age-related improvement in search rate (response time slope over number of items) was different for patterns defined by short- versus long-range spatial relations. Perceptual access to each type of relation was varied by using elements of same contrast (easy to access) or mixed contrast (hard to access). The results showed large improvements with age in search rate for long-range targets; search rate for short-range targets was fairly constant across age. This pattern held regardless of whether perceptual access to a target was easy or hard, supporting the hypothesis that different processes are involved in perceptual grouping at these two levels. The results also point to important links between ontogenic and microgenic change in perception (H. Werner, 1948, 1957).
Search systems and computer-implemented search methods

DOEpatents

Payne, Deborah A.; Burtner, Edwin R.; Hampton, Shawn D.; Gillen, David S.; Henry, Michael J.

2017-03-07

Search systems and computer-implemented search methods are described. In one aspect, a search system includes a communications interface configured to access a plurality of data items of a collection, wherein the data items include a plurality of image objects individually comprising image data utilized to generate an image of the respective data item. The search system may include processing circuitry coupled with the communications interface and configured to process the image data of the data items of the collection to identify a plurality of image content facets which are indicative of image content contained within the images and to associate the image objects with the image content facets and a display coupled with the processing circuitry and configured to depict the image objects associated with the image content facets.
Search systems and computer-implemented search methods

DOEpatents

Payne, Deborah A.; Burtner, Edwin R.; Bohn, Shawn J.; Hampton, Shawn D.; Gillen, David S.; Henry, Michael J.

2015-12-22

Search systems and computer-implemented search methods are described. In one aspect, a search system includes a communications interface configured to access a plurality of data items of a collection, wherein the data items include a plurality of image objects individually comprising image data utilized to generate an image of the respective data item. The search system may include processing circuitry coupled with the communications interface and configured to process the image data of the data items of the collection to identify a plurality of image content facets which are indicative of image content contained within the images and to associate the image objects with the image content facets and a display coupled with the processing circuitry and configured to depict the image objects associated with the image content facets.
Facilitating the 3D Indoor Search and Rescue Problem: An Overview of the Problem and an Ant Colony Solution Approach

NASA Astrophysics Data System (ADS)

Tashakkori, H.; Rajabifard, A.; Kalantari, M.

2016-10-01

Search and rescue procedures for indoor environments are quite complicated due to the fact that much of the indoor information is unavailable to rescuers before physical entrance to the incident scene. Thus, decision making regarding the number of crew required and the way they should be dispatched in the building considering the various access points and complexities in the buildings in order to cover the search area in minimum time is dependent on prior knowledge and experience of the emergency commanders. Hence, this paper introduces the Search and Rescue Problem (SRP) which aims at finding best search and rescue routes that minimize the overall search time in the buildings. 3D BIM-oriented indoor GIS is integrated in the indoor route graph to find accurate routes based on the building geometric and semantic information. An Ant Colony Based Algorithm is presented that finds the number of first responders required and their individual routes to search all rooms and points of interest inside the building to minimize the overall time spent by all rescuers inside the disaster area. The evaluation of the proposed model for a case study building shows a significant improve in search and rescue time which will lead to a higher chance of saving lives and less exposure of emergency crew to danger.
Broadcasting satellite service synthesis using gradient and cyclic coordinate search procedures

NASA Technical Reports Server (NTRS)

Reilly, C. H.; Mount-Campbell, C. A.; Gonsalvez, D. J.; Martin, C. H.; Levis, C. A.; Wang, C. W.

1986-01-01

Two search techniques are considered for solving satellite synthesis problems. Neither is likely to find a globally optimal solution. In order to determine which method performs better and what factors affect their performance, we design an experiment and solve the same problem under a variety of starting solution configuration-algorithm combinations. Since there is no randomization in the experiment, we present results of practical, rather than statistical, significance. Our implementation of a cyclic coordinate search procedure clearly finds better synthesis solutions than our implementation of a gradient search procedure does with our objective of maximizing the minimum C/I ratio computed at test points on the perimeters of the intended service areas. The length of the available orbital arc and the configuration of the starting solution are shown to affect the quality of the solutions found.
The Chicken Soup Effect: The Role of Recreation and Intramural Participation in Boosting Freshman Grade Point Average

ERIC Educational Resources Information Center

Gibbison, Godfrey A.; Henry, Tracyann L.; Perkins-Brown, Jayne

2011-01-01

Freshman grade point average, in particular first semester grade point average, is an important predictor of survival and eventual student success in college. As many institutions of higher learning are searching for ways to improve student success, one would hope that policies geared towards the success of freshmen have long term benefits…
Age differences in search of web pages: the effects of link size, link number, and clutter.

PubMed

Grahame, Michael; Laberge, Jason; Scialfa, Charles T

2004-01-01

Reaction time, eye movements, and errors were measured during visual search of Web pages to determine age-related differences in performance as a function of link size, link number, link location, and clutter. Participants (15 young adults, M = 23 years; 14 older adults, M = 57 years) searched Web pages for target links that varied from trial to trial. During one half of the trials, links were enlarged from 10-point to 12-point font. Target location was distributed among the left, center, and bottom portions of the screen. Clutter was manipulated according to the percentage of used space, including graphics and text, and the number of potentially distracting nontarget links was varied. Increased link size improved performance, whereas increased clutter and links hampered search, especially for older adults. Results also showed that links located in the left region of the page were found most easily. Actual or potential applications of this research include Web site design to increase usability, particularly for older adults.
Acoustic-to-Seismic Coupling Over Porous Ground Surfaces.

DTIC Science & Technology

1984-01-01

of sound into the ground is predicted for both spherical and plane acoustic waves incident upon two models of the ground viz i) a rigid porous solid...and soils of above-ground acoustic disturbances. Furthermore it is found possible to predict the results of model measurements using continuous and...saddle point 2.4 The geometrical wave 2.5 The lateral wave 2.6 Special cases 3. POINT TO POINT PROPAGATION MEASUREMENTS USING ACOUSTIC MODELLING " 3.0
Maintaining the momentum of Open Search in Earth Science Data discovery

NASA Astrophysics Data System (ADS)

Newman, D. J.; Lynnes, C.

2013-12-01

Federated Search for Earth Observation data has been a hallmark of EOSDIS (Earth Observing System Data and Information System) for two decades. Originally, the EOSDIS Version 0 system provided both data-collection-level and granule/file-level search in the mid 1990s with EOSDIS-specific socket protocols and message formats. Since that time, the advent of several standards has helped to simplify EOSDIS federated search, beginning with HTTP as the transfer protocol. Most recently, OpenSearch (www.opensearch.org) was employed for the EOS Clearinghouse (ECHO), based on a set of conventions that had been developed within the Earth Science Information Partners (ESIP) Federation. The ECHO OpenSearch API has evolved to encompass the ESIP RFC and the Open Geospatial Consortium (OGC) Open Search standard. Uptake of the ECHO Open Search API has been significant and has made ECHO accessible to client developers that found the previous ECHO SOAP API and current REST API too complex. Client adoption of the OpenSearch API appears to be largely driven by the simplicity of the OpenSearch convention. This simplicity is thus important to retain as the standard and convention evolve. For example, ECHO metrics indicate that the vast majority of ECHO users favor the following search criteria when using the REST API, - Spatial - bounding box, polygon, line and point - Temporal - start and end time - Keywords - free text Fewer than 10% of searches use additional constraints, particularly those requiring a controlled vocabulary, such as instrument, sensor, etc. This suggests that ongoing standardization efforts around OpenSearch usage for Earth Observation data may be more productive if oriented toward improving support for the Spatial, Temporal and Keyword search aspects. Areas still requiring improvement include support of - Concrete requirements for keyword constraints - Phrasal search for keyword constraints - Temporal constraint relations - Terminological symmetry between search URLs
Pulse bifurcations and instabilities in an excitable medium: Computations in finite ring domains

NASA Astrophysics Data System (ADS)

Or-Guil, M.; Krishnan, J.; Kevrekidis, I. G.; Bär, M.

2001-10-01

We investigate the instabilities and bifurcations of traveling pulses in a model excitable medium; in particular, we discuss three different scenarios involving either the loss of stability or disappearance of stable pulses. In numerical simulations beyond the instabilities we observe replication of pulses (``backfiring'') resulting in complex periodic or spatiotemporally chaotic dynamics as well as modulated traveling pulses. We approximate the linear stability of traveling pulses through computations in a finite albeit large domain with periodic boundary conditions. The critical eigenmodes at the onset of the instabilities are related to the resulting spatiotemporal dynamics and ``act'' upon the back of the pulses. The first scenario has been analyzed earlier [M. G. Zimmermann et al., Physica D 110, 92 (1997)] for high excitability (low excitation threshold): it involves the collision of a stable pulse branch with an unstable pulse branch in a so-called T point. In the framework of traveling wave ordinary differential equations, pulses correspond to homoclinic orbits and the T point to a double heteroclinic loop. We investigate this transition for a pulse in a domain with finite length and periodic boundary conditions. Numerical evidence of the proximity of the infinite-domain T point in this setup appears in the form of two saddle node bifurcations. Alternatively, for intermediate excitation threshold, an entire cascade of saddle nodes causing a ``spiraling'' of the pulse branch appears near the parameter values corresponding to the infinite-domain T point. Backfiring appears at the first saddle-node bifurcation, which limits the existence region of stable pulses. The third case found in the model for large excitation threshold is an oscillatory instability giving rise to ``breathing,'' traveling pulses that periodically vary in width and speed.
Double-inversion mechanisms of the X⁻ + CH₃Y [X,Y = F, Cl, Br, I] SN2 reactions.

PubMed

Szabó, István; Czakó, Gábor

2015-03-26

The double-inversion and front-side attack transition states as well as the proton-abstraction channels of the X(-) + CH3Y [X,Y = F, Cl, Br, I] reactions are characterized by the explicitly correlated CCSD(T)-F12b/aug-cc-pVTZ(-PP) level of theory using small-core relativistic effective core potentials and the corresponding aug-cc-pVTZ-PP bases for Br and I. In the X = F case the double-inversion classical(adiabatic) barrier heights are 28.7(25.6), 15.8(13.4), 13.2(11.0), and 8.6(6.6) kcal mol(-1) for Y = F, Cl, Br, and I, respectively, whereas the barrier heights are in the 40-90 kcal mol(-1) range for the other 12 reactions. The abstraction channels are always above the double-inversion saddle points. For X = F, the front-side attack classical(adiabatic) barrier heights, 45.8(44.8), 31.0(30.3), 24.7(24.2), and 19.5(19.3) kcal mol(-1) for Y = F, Cl, Br, and I, respectively, are higher than the corresponding double-inversion ones, whereas for the other systems the front-side attack saddle points are in the 35-70 kcal mol(-1) range. The double-inversion transition states have XH···CH2Y(-) structures with Cs point-group symmetry, and the front-side attack saddle points have either Cs (X = F or X = Y) or C1 symmetry with XCY angles in the 78-88° range. On the basis of the previous reaction dynamics simulations and the minimum energy path computations along the inversion coordinate of selected XH···CH2Y(-) systems, we suggest that the double inversion may be a general mechanism for SN2 reactions.
Suspicionless Searches.

ERIC Educational Resources Information Center

Zirkel, Perry A.

2000-01-01

In a federal case involving a vice-principal's pat-down search of middle-school students in a cafeteria (for a missing pizza knife), the court upheld the search, saying it was relatively unintrusive and met "TLO's" reasonable-suspicion standards. Principals need reasonable justification for searching a group. (Contains 18 references.)…
Meta Search Engines.

ERIC Educational Resources Information Center

Garman, Nancy

1999-01-01

Describes common options and features to consider in evaluating which meta search engine will best meet a searcher's needs. Discusses number and names of engines searched; other sources and specialty engines; search queries; other search options; and results options. (AEF)

Supervised learning of tools for content-based search of image databases

NASA Astrophysics Data System (ADS)

Delanoy, Richard L.

1996-03-01

A computer environment, called the Toolkit for Image Mining (TIM), is being developed with the goal of enabling users with diverse interests and varied computer skills to create search tools for content-based image retrieval and other pattern matching tasks. Search tools are generated using a simple paradigm of supervised learning that is based on the user pointing at mistakes of classification made by the current search tool. As mistakes are identified, a learning algorithm uses the identified mistakes to build up a model of the user's intentions, construct a new search tool, apply the search tool to a test image, display the match results as feedback to the user, and accept new inputs from the user. Search tools are constructed in the form of functional templates, which are generalized matched filters capable of knowledge- based image processing. The ability of this system to learn the user's intentions from experience contrasts with other existing approaches to content-based image retrieval that base searches on the characteristics of a single input example or on a predefined and semantically- constrained textual query. Currently, TIM is capable of learning spectral and textural patterns, but should be adaptable to the learning of shapes, as well. Possible applications of TIM include not only content-based image retrieval, but also quantitative image analysis, the generation of metadata for annotating images, data prioritization or data reduction in bandwidth-limited situations, and the construction of components for larger, more complex computer vision algorithms.
Provisional-Ideal-Point-Based Multi-objective Optimization Method for Drone Delivery Problem

NASA Astrophysics Data System (ADS)

Omagari, Hiroki; Higashino, Shin-Ichiro

2018-04-01

In this paper, we proposed a new evolutionary multi-objective optimization method for solving drone delivery problems (DDP). It can be formulated as a constrained multi-objective optimization problem. In our previous research, we proposed the "aspiration-point-based method" to solve multi-objective optimization problems. However, this method needs to calculate the optimal values of each objective function value in advance. Moreover, it does not consider the constraint conditions except for the objective functions. Therefore, it cannot apply to DDP which has many constraint conditions. To solve these issues, we proposed "provisional-ideal-point-based method." The proposed method defines a "penalty value" to search for feasible solutions. It also defines a new reference solution named "provisional-ideal point" to search for the preferred solution for a decision maker. In this way, we can eliminate the preliminary calculations and its limited application scope. The results of the benchmark test problems show that the proposed method can generate the preferred solution efficiently. The usefulness of the proposed method is also demonstrated by applying it to DDP. As a result, the delivery path when combining one drone and one truck drastically reduces the traveling distance and the delivery time compared with the case of using only one truck.
Lyman Alpha Searches at Redshift Z>7

NASA Astrophysics Data System (ADS)

Willis, Jon

2007-05-01

The ZEN survey is a narrow J-band survey for Ly-alpha emitting galaxies at z > 7. I will briefly review the pros and cons of narrow band observations before summarising the ZEN1 and ZEN2 searches based upon deep ISAAC pointings. I will then present ZEN3, consisting of wide field, narrow band observations of two fields using the CFHT WIRCam facility. I will conclude by reviewing the current sample of candidates and what we have learned about the z > 7 Ly-alpha emitting population.
Beyond the search surface: visual search and attentional engagement.

PubMed

Duncan, J; Humphreys, G

1992-05-01

Treisman (1991) described a series of visual search studies testing feature integration theory against an alternative (Duncan & Humphreys, 1989) in which feature and conjunction search are basically similar. Here the latter account is noted to have 2 distinct levels: (a) a summary of search findings in terms of stimulus similarities, and (b) a theory of how visual attention is brought to bear on relevant objects. Working at the 1st level, Treisman found that even when similarities were calibrated and controlled, conjunction search was much harder than feature search. The theory, however, can only really be tested at the 2nd level, because the 1st is an approximation. An account of the findings is developed at the 2nd level, based on the 2 processes of input-template matching and spreading suppression. New data show that, when both of these factors are controlled, feature and conjunction search are equally difficult. Possibilities for unification of the alternative views are considered.
Interest in Anesthesia as Reflected by Keyword Searches using Common Search Engines.

PubMed

Liu, Renyu; García, Paul S; Fleisher, Lee A

2012-01-23

Since current general interest in anesthesia is unknown, we analyzed internet keyword searches to gauge general interest in anesthesia in comparison with surgery and pain. The trend of keyword searches from 2004 to 2010 related to anesthesia and anaesthesia was investigated using Google Insights for Search. The trend of number of peer reviewed articles on anesthesia cited on PubMed and Medline from 2004 to 2010 was investigated. The average cost on advertising on anesthesia, surgery and pain was estimated using Google AdWords. Searching results in other common search engines were also analyzed. Correlation between year and relative number of searches was determined with p< 0.05 considered statistically significant. Searches for the keyword "anesthesia" or "anaesthesia" diminished since 2004 reflected by Google Insights for Search (p< 0.05). The search for "anesthesia side effects" is trending up over the same time period while the search for "anesthesia and safety" is trending down. The search phrase "before anesthesia" is searched more frequently than "preanesthesia" and the search for "before anesthesia" is trending up. Using "pain" as a keyword is steadily increasing over the years indicated. While different search engines may provide different total number of searching results (available posts), the ratios of searching results between some common keywords related to perioperative care are comparable, indicating similar trend. The peer reviewed manuscripts on "anesthesia" and the proportion of papers on "anesthesia and outcome" are trending up. Estimates for spending of advertising dollars are less for anesthesia-related terms when compared to that for pain or surgery due to relative smaller number of searching traffic. General interest in anesthesia (anaesthesia) as measured by internet searches appears to be decreasing. Pain, preanesthesia evaluation, anesthesia and outcome and side effects of anesthesia are the critical areas that anesthesiologists should
An ab initio study of the potential energy surface in the S 1 state of 2-hydroxypyridine

NASA Astrophysics Data System (ADS)

Sobolewski, Andrzej L.; Adamowicz, Ludwik

1996-12-01

The potential energy (PE) surface of the lowest excited singlet state relevant to the photophysics of interconversion of the 2-hydroxypyridine/2 (1H)-pyridinone (2HP/2PY) system is characterized by ab initio calculations. The geometry optimizations in the S 1 state performed at the CIS/6-31G (d,p) level confirm the experimental findings that the 2HP form is planar in this state whereas the 2PY form is significantly out-of-plane distorted. The lowest-energy first-order saddle-points which are relevant to the photophysics of the "mobile" hydrogen atom on the S 1 PE surface lead toward its dissociation from the molecule. There is no saddle-point for a "direct" proton transfer reaction on the S 1 PE surface leading from the 2HP form to the 2PY form. The results confirm the hypothesis that the photo-induced dissociation-association (PIDA) mechanism is probably responsible for the excited-state tautomerization observed in this system.
Electronic structure and molecular dynamics of Na2Li

NASA Astrophysics Data System (ADS)

Malcolm, Nathaniel O. J.; McDouall, Joseph J. W.

Following the first report (Mile, B., Sillman, P. D., Yacob, A. R. and Howard, J. A., 1996, J. chem. Soc. Dalton Trans , 653) of the EPR spectrum of the mixed alkali-metal trimer Na2Li a detailed study has been made of the electronic structure and structural dynamics of this species. Two isomeric forms have been found: one of the type, Na-Li-Na, of C , symmetry and another, Li-Na-Na, of C symmetry. Also, there are two linear saddle points which correspond to 'inversion' transition structures, and a saddle point of C symmetry which connects the two minima. A molecular dynamics investigation of these species shows that, at the temperature of the reported experiments (170 K), the C minimum is not 'static', but undergoes quite rapid inversion. At higher temperatures the C minimum converts to the C form, but by a mechanism very different from that suggested by minimum energy path considerations. 2 2v s s 2v 2v s
Development and Validation of Search Filters to Identify Articles on Family Medicine in Online Medical Databases

PubMed Central

Pols, David H.J.; Bramer, Wichor M.; Bindels, Patrick J.E.; van de Laar, Floris A.; Bohnen, Arthur M.

2015-01-01

Physicians and researchers in the field of family medicine often need to find relevant articles in online medical databases for a variety of reasons. Because a search filter may help improve the efficiency and quality of such searches, we aimed to develop and validate search filters to identify research studies of relevance to family medicine. Using a new and objective method for search filter development, we developed and validated 2 search filters for family medicine. The sensitive filter had a sensitivity of 96.8% and a specificity of 74.9%. The specific filter had a specificity of 97.4% and a sensitivity of 90.3%. Our new filters should aid literature searches in the family medicine field. The sensitive filter may help researchers conducting systematic reviews, whereas the specific filter may help family physicians find answers to clinical questions at the point of care when time is limited. PMID:26195683
Horizontal visual search in a large field by patients with unilateral spatial neglect.

PubMed

Nakatani, Ken; Notoya, Masako; Sunahara, Nobuyuki; Takahashi, Shusuke; Inoue, Katsumi

2013-06-01

In this study, we investigated the horizontal visual search ability and pattern of horizontal visual search in a large space performed by patients with unilateral spatial neglect (USN). Subjects included nine patients with right hemisphere damage caused by cerebrovascular disease showing left USN, nine patients with right hemisphere damage but no USN, and six healthy individuals with no history of brain damage who were age-matched to the groups with brain right hemisphere damage. The number of visual search tasks accomplished was recorded in the first experiment. Neck rotation angle was continuously measured during the task and quantitative data of the measurements were collected. There was a strong correlation between the number of visual search tasks accomplished and the total Behavioral Inattention Test Conventional Subtest (BITC) score in subjects with right hemisphere damage. In both USN and control groups, the head position during the visual search task showed a balanced bell-shaped distribution from the central point on the field to the left and right sides. Our results indicate that compensatory strategies, including cervical rotation, may improve visual search capability and achieve balance on the neglected side. Copyright © 2012 Elsevier Ltd. All rights reserved.
Monitoring urban subsidence based on SAR lnterferometric point target analysis

USGS Publications Warehouse

Zhang, Y.; Zhang, Jiahua; Gong, W.; Lu, Z.

2009-01-01

lnterferometric point target analysis (IPTA) is one of the latest developments in radar interferometric processing. It is achieved by analysis of the interferometric phases of some individual point targets, which are discrete and present temporarily stable backscattering characteristics, in long temporal series of interferometric SAR images. This paper analyzes the interferometric phase model of point targets, and then addresses two key issues within IPTA process. Firstly, a spatial searching method is proposed to unwrap the interferometric phase difference between two neighboring point targets. The height residual error and linear deformation rate of each point target can then be calculated, when a global reference point with known height correction and deformation history is chosen. Secondly, a spatial-temporal filtering scheme is proposed to further separate the atmosphere phase and nonlinear deformation phase from the residual interferometric phase. Finally, an experiment of the developed IPTA methodology is conducted over Suzhou urban area. Totally 38 ERS-1/2 SAR scenes are analyzed, and the deformation information over 3 546 point targets in the time span of 1992-2002 are generated. The IPTA-derived deformation shows very good agreement with the published result, which demonstrates that the IPTA technique can be developed into an operational tool to map the ground subsidence over urban area.
Interest in Anesthesia as Reflected by Keyword Searches using Common Search Engines

PubMed Central

Liu, Renyu; García, Paul S.; Fleisher, Lee A.

2012-01-01

Background Since current general interest in anesthesia is unknown, we analyzed internet keyword searches to gauge general interest in anesthesia in comparison with surgery and pain. Methods The trend of keyword searches from 2004 to 2010 related to anesthesia and anaesthesia was investigated using Google Insights for Search. The trend of number of peer reviewed articles on anesthesia cited on PubMed and Medline from 2004 to 2010 was investigated. The average cost on advertising on anesthesia, surgery and pain was estimated using Google AdWords. Searching results in other common search engines were also analyzed. Correlation between year and relative number of searches was determined with p< 0.05 considered statistically significant. Results Searches for the keyword “anesthesia” or “anaesthesia” diminished since 2004 reflected by Google Insights for Search (p< 0.05). The search for “anesthesia side effects” is trending up over the same time period while the search for “anesthesia and safety” is trending down. The search phrase “before anesthesia” is searched more frequently than “preanesthesia” and the search for “before anesthesia” is trending up. Using “pain” as a keyword is steadily increasing over the years indicated. While different search engines may provide different total number of searching results (available posts), the ratios of searching results between some common keywords related to perioperative care are comparable, indicating similar trend. The peer reviewed manuscripts on “anesthesia” and the proportion of papers on “anesthesia and outcome” are trending up. Estimates for spending of advertising dollars are less for anesthesia-related terms when compared to that for pain or surgery due to relative smaller number of searching traffic. Conclusions General interest in anesthesia (anaesthesia) as measured by internet searches appears to be decreasing. Pain, preanesthesia evaluation, anesthesia and outcome and side
Search time critically depends on irrelevant subset size in visual search.

PubMed

Benjamins, Jeroen S; Hooge, Ignace T C; van Elst, Jacco C; Wertheim, Alexander H; Verstraten, Frans A J

2009-02-01

In order for our visual system to deal with the massive amount of sensory input, some of this input is discarded, while other parts are processed [Wolfe, J. M. (1994). Guided search 2.0: a revised model of visual search. Psychonomic Bulletin and Review, 1, 202-238]. From the visual search literature it is unclear how well one set of items can be selected that differs in only one feature from target (a 1F set), while another set of items can be ignored that differs in two features from target (a 2F set). We systematically varied the percentage of 2F non-targets to determine the contribution of these non-targets to search behaviour. Increasing the percentage 2F non-targets, that have to be ignored, was expected to result in increasingly faster search, since it decreases the size of 1F set that has to be searched. Observers searched large displays for a target in the 1F set with a variable percentage of 2F non-targets. Interestingly, when the search displays contained 5% 2F non-targets, the search time was longer compared to the search time in other conditions. This effect of 2F non-targets on performance was independent of set size. An inspection of the saccades revealed that saccade target selection did not contribute to the longer search times in displays with 5% 2F non-targets. Occurrence of longer search times in displays containing 5% 2F non-targets might be attributed to covert processes related to visual analysis of the fixated part of the display. Apparently, visual search performance critically depends on the percentage of irrelevant 2F non-targets.
The Stability of Tidal Equilibrium for Hierarchical Star-Planet-Moon Systems

NASA Astrophysics Data System (ADS)

Adams, Fred C.

2018-04-01

Motivated by the current search for exomoons, this talk considers the stability of tidal equilibrium for hierarchical three-body systems containing a star, a planet, and a moon. In this treatment, the energy and angular momentum budgets include contributions from the planetary orbit, lunar orbit, stellar spin, planetary spin, and lunar spin. The goal is to determine the optimized energy state of the system subject to the constraint of constant angular momentum. Due to the lack of a closed form solution for the full three-body problem, however, we must use use an approximate description of the orbits. We first consider the Keplerian limit and find that the critical energy states are saddle points, rather than minima, so that these hierarchical systems have no stable tidal equilibrium states. We then generalize the calculation so that the lunar orbit is described by a time-averaged version of the circular restricted three-body problem. In this latter case, the critical energy state is a shallow minimum, so that a tidal equilibrium state exists. In both cases, however, the lunar orbit for the critical point lies outside the boundary (roughly half the Hill radius) where (previous) numerical simulations indicate dynamical instability.
Photodetectors on Coronagraph Mask for Pointing Control

NASA Technical Reports Server (NTRS)

Balasubramanian, Kunjithapatham

2007-01-01

It has been proposed to install a symmetrical array of photodetectors about the center of the mask of a coronagraph of the type used to search for planets orbiting remote stars. The purpose of this installation is to utilize the light from a star under observation as a guide in pointing the telescope. Simple arithmetic processing of the outputs of the photodetectors would provide indications of the lateral position of the center of the mask relative to the center of the image of the star. These indications could serve as pointing-control feedback signals for adjusting the telescope aim to center the image of the star on the mask. The widths of central mask areas available for placement of photodetectors differ among coronagraph designs, typically ranging upward from about 100 m. Arrays of photodetectors can readily be placed within areas in this size range. The number of detectors in an array could be as small as 4 or as large as 64. The upper limit on the number of detectors would be determined according to the extent of the occulting pattern and the number of functionalities, in addition to pointing control, to be served by the array.
Mars - Satellite and ring search from Viking

NASA Technical Reports Server (NTRS)

Duxbury, Thomas C.; Ocampo, Adriana C.

1988-01-01

Viking Orbiter 1 imaging data were used in a search for possible satellites and rings of Mars in 1980, giving attention to a region within the Phobos orbit and + or - 350 km about the Martian equatorial plane. After picture processing, no images other than stars and Phobos itself were found to be a few brightnesses (or more) above their surrounding, as would be expected in the case of a point-spread, 'smeared' image of either satellites or rings. There is therefore no evidence of any such phenomenon in the 78 pictures studied.
Density Functional Theory Calculations of the Dissociation of H[2] on (100) 2H-MoS[2] Surfaces: A Key Step in the Hydroprocessing of Crude Oil

ERIC Educational Resources Information Center

Todorova, Teodora; Alexiev, Valentin; Weber, Thomas

2006-01-01

Hydrogen activation on the (100) surface of MoS[2] structures was investigated by means of density functional theory calculations. Linear and quadratic synchronous transit methods with a conjugate gradient refinement of the saddle point were used to localize transition states. The calculations include heterolytic and homolytic dissociation of…
Web Searching: A Process-Oriented Experimental Study of Three Interactive Search Paradigms.

ERIC Educational Resources Information Center

Dennis, Simon; Bruza, Peter; McArthur, Robert

2002-01-01

Compares search effectiveness when using query-based Internet search via the Google search engine, directory-based search via Yahoo, and phrase-based query reformulation-assisted search via the Hyperindex browser by means of a controlled, user-based experimental study of undergraduates at the University of Queensland. Discusses cognitive load,…
Application of GIS-based models for delineating the UAV flight region to support Search and Rescue activities

NASA Astrophysics Data System (ADS)

Jurecka, Miroslawa; Niedzielski, Tomasz

2017-04-01

The objective of the approach presented in this paper is to demonstrate a potential of using the combination of two GIS-based models - mobility model and ring model - for delineating a region above which an Unmanned Aerial Vehicle (UAV) should fly to support the Search and Rescue (SAR) activities. The procedure is based on two concepts, both describing a possible distance/path that lost person could travel from the initial planning point (being either the point last seen, or point last known). The first approach (the ring model) takes into account the crow's flight distance traveled by a lost person and its probability distribution. The second concept (the mobility model) is based on the estimated travel speed and the associated features of the geographical environment of the search area. In contrast to the ring model covering global (hence more general) SAR perspective, the mobility model represents regional viewpoint by taking into consideration local impedance. Both models working together can serve well as a starting point for the UAV flight planning to strengthen the SAR procedures. We present the method of combining the two above-mentioned models in order to delineate UAVs flight region and increase the Probability of Success for future SAR missions. The procedure is a part of a larger Search and Rescue (SAR) system which is being developed at the University of Wrocław, Poland (research project no. IP2014 032773 financed by the Ministry of Science and Higher Education of Poland). The mobility and ring models have been applied to the Polish territory, and they act in concert to provide the UAV operator with the optimal search region. This is attained in real time so that the UAV-based SAR mission can be initiated quickly.
Accuracy limit of rigid 3-point water models

NASA Astrophysics Data System (ADS)

Izadi, Saeed; Onufriev, Alexey V.

2016-08-01

Classical 3-point rigid water models are most widely used due to their computational efficiency. Recently, we introduced a new approach to constructing classical rigid water models [S. Izadi et al., J. Phys. Chem. Lett. 5, 3863 (2014)], which permits a virtually exhaustive search for globally optimal model parameters in the sub-space that is most relevant to the electrostatic properties of the water molecule in liquid phase. Here we apply the approach to develop a 3-point Optimal Point Charge (OPC3) water model. OPC3 is significantly more accurate than the commonly used water models of same class (TIP3P and SPCE) in reproducing a comprehensive set of liquid bulk properties, over a wide range of temperatures. Beyond bulk properties, we show that OPC3 predicts the intrinsic charge hydration asymmetry (CHA) of water — a characteristic dependence of hydration free energy on the sign of the solute charge — in very close agreement with experiment. Two other recent 3-point rigid water models, TIP3PFB and H2ODC, each developed by its own, completely different optimization method, approach the global accuracy optimum represented by OPC3 in both the parameter space and accuracy of bulk properties. Thus, we argue that an accuracy limit of practical 3-point rigid non-polarizable models has effectively been reached; remaining accuracy issues are discussed.
An Arecibo Search for Pulsars and Transient Sources in M33

NASA Astrophysics Data System (ADS)

Bhat, N. D. R.; Cordes, J. M.; Cox, P. J.; Deneva, J. S.; Hankins, T. H.; Lazio, T. J. W.; McLaughlin, M. A.

2011-05-01

We report on a systematic and sensitive search for pulsars and transient sources in the nearby spiral galaxy M33, conducted at 1.4 GHz with the Arecibo telescope's seven-beam receiver system, ALFA. Data were searched for both periodic and aperiodic sources, up to 1000 pc cm-3 in dispersion measure and on timescales from ~50 μs to several seconds. The galaxy was sampled with 12 ALFA pointings, or 84 pixels in total, each of which was searched for 2-3 hr. We describe the observations, search methodologies, and analysis strategies applicable to multibeam systems, and comment on the data quality and statistics of spurious events that arise due to radio frequency interference. While these searches have not led to any conclusive signals of periodic or transient nature that originate in the galaxy, they illustrate some of the underlying challenges and difficulties in such searches and the efficacy of simultaneous multiple beams in the analysis of search output. The implied limits are lsim5 μJy Mpc2 in luminosity (at 1400 MHz) for periodic sources in M33 with duty cycles lsim5%. For short-duration transient signals (with pulse widths lsim100 μs ), the limiting peak flux density is 100 mJy, which would correspond to a 5σ detection of bright giant pulses (~20 kJy) from Crab-like pulsars if located at the distance of M33. We discuss the implications of our null results for various source populations within the galaxy and comment on the future prospects to conduct even more sensitive searches with the upcoming next-generation instruments including the Square Kilometer Array and its pathfinders.

An Alternative to QUERY: Batch-Searching of the ERIC Information Collections.

ERIC Educational Resources Information Center

Krahmer, Edward; Horne, Kent

A manual describing the RIC computer search program for retrieval of information from ERIC, CIJE, and other collections is presented. It is pointed out that two versions of this program have been developed. The first is for an IBM 360/370 computer. This version has been operational on a production basis for nearly a year. Four installations of…
Search for evidence of low energy protons in solar flares

NASA Technical Reports Server (NTRS)

Metcalf, Thomas R.; Wuelser, Jean-Pierre; Canfield, Richard C.; Hudson, Hugh S.

1992-01-01

We searched for linear polarization in the H alpha line using the Stokes Polarimeter at Mees Solar Observatory and present observations of a flare from NOAA active region 6659 which began at 01:30 UT on 14 Jun. 1991. Our dataset also includes H alpha spectra from the Mees charge coupled device (MCCD) imaging spectrograph as well as hard x ray observations from the Burst and Transient Source Experiment (BATSE) instrument on board the Gamma Ray Observatory (GRO). The polarimeter scanned a 40 x 40 inch field of view using 16 raster points in a 4 x 4 grid. Each scan took about 30 seconds with 2 seconds at each raster point. The polarimeter stopped 8.5 inches between raster points and each point covered a 6 inch region. This sparse sampling increased the total field of view without reducing the temporal cadence. At each raster point, an H alpha spectrum with 20 mA spectral sampling is obtained covering 2.6 A centered on H alpha line center. The preliminary conclusions from the research are presented.
The uniform asymptotic swallowtail approximation - Practical methods for oscillating integrals with four coalescing saddle points

NASA Technical Reports Server (NTRS)

Connor, J. N. L.; Curtis, P. R.; Farrelly, D.

1984-01-01

Methods that can be used in the numerical implementation of the uniform swallowtail approximation are described. An explicit expression for that approximation is presented to the lowest order, showing that there are three problems which must be overcome in practice before the approximation can be applied to any given problem. It is shown that a recently developed quadrature method can be used for the accurate numerical evaluation of the swallowtail canonical integral and its partial derivatives. Isometric plots of these are presented to illustrate some of their properties. The problem of obtaining the arguments of the swallowtail integral from an analytical function of its argument is considered, describing two methods of solving this problem. The asymptotic evaluation of the butterfly canonical integral is addressed.
Development and Validation of Search Filters to Identify Articles on Family Medicine in Online Medical Databases.

PubMed

Pols, David H J; Bramer, Wichor M; Bindels, Patrick J E; van de Laar, Floris A; Bohnen, Arthur M

2015-01-01

Physicians and researchers in the field of family medicine often need to find relevant articles in online medical databases for a variety of reasons. Because a search filter may help improve the efficiency and quality of such searches, we aimed to develop and validate search filters to identify research studies of relevance to family medicine. Using a new and objective method for search filter development, we developed and validated 2 search filters for family medicine. The sensitive filter had a sensitivity of 96.8% and a specificity of 74.9%. The specific filter had a specificity of 97.4% and a sensitivity of 90.3%. Our new filters should aid literature searches in the family medicine field. The sensitive filter may help researchers conducting systematic reviews, whereas the specific filter may help family physicians find answers to clinical questions at the point of care when time is limited. © 2015 Annals of Family Medicine, Inc.
Teaching Evidence-Based Medicine in the Era of Point-of-Care Databases: The Case of the Giant Bladder Stone.

PubMed

Kash, Melissa J

2016-01-01

In an era where physicians rely on point-of-care databases that provide filtered, pre-appraised, and quickly accessible clinical information by smartphone applications, it is difficult to teach medical students the importance of knowing not only when it is appropriate to search the primary medical literature but also how to do it. This column will describe how librarians at an academic health sciences library use an unusual clinical case to make demonstrations of searching primary medical literature real and meaningful to medical students, and to illustrate vividly the importance of knowing what to do when the answer to a clinical question cannot be found in a point-of-care database.
Impact of PubMed search filters on the retrieval of evidence by physicians.

PubMed

Shariff, Salimah Z; Sontrop, Jessica M; Haynes, R Brian; Iansavichus, Arthur V; McKibbon, K Ann; Wilczynski, Nancy L; Weir, Matthew A; Speechley, Mark R; Thind, Amardeep; Garg, Amit X

2012-02-21

Physicians face challenges when searching PubMed for research evidence, and they may miss relevant articles while retrieving too many nonrelevant articles. We investigated whether the use of search filters in PubMed improves searching by physicians. We asked a random sample of Canadian nephrologists to answer unique clinical questions derived from 100 systematic reviews of renal therapy. Physicians provided the search terms that they would type into PubMed to locate articles to answer these questions. We entered the physician-provided search terms into PubMed and applied two types of search filters alone or in combination: a methods-based filter designed to identify high-quality studies about treatment (clinical queries "therapy") and a topic-based filter designed to identify studies with renal content. We evaluated the comprehensiveness (proportion of relevant articles found) and efficiency (ratio of relevant to nonrelevant articles) of the filtered and nonfiltered searches. Primary studies included in the systematic reviews served as the reference standard for relevant articles. The average physician-provided search terms retrieved 46% of the relevant articles, while 6% of the retrieved articles were relevant (corrected) (the ratio of relevant to nonrelevant articles was 1:16). The use of both filters together produced a marked improvement in efficiency, resulting in a ratio of relevant to nonrelevant articles of 1:5 (16 percentage point improvement; 99% confidence interval 9% to 22%; p < 0.003) with no substantive change in comprehensiveness (44% of relevant articles found; p = 0.55). The use of PubMed search filters improves the efficiency of physician searches. Improved search performance may enhance the transfer of research into practice and improve patient care.
Does linear separability really matter? Complex visual search is explained by simple search

PubMed Central

Vighneshvel, T.; Arun, S. P.

2013-01-01

Visual search in real life involves complex displays with a target among multiple types of distracters, but in the laboratory, it is often tested using simple displays with identical distracters. Can complex search be understood in terms of simple searches? This link may not be straightforward if complex search has emergent properties. One such property is linear separability, whereby search is hard when a target cannot be separated from its distracters using a single linear boundary. However, evidence in favor of linear separability is based on testing stimulus configurations in an external parametric space that need not be related to their true perceptual representation. We therefore set out to assess whether linear separability influences complex search at all. Our null hypothesis was that complex search performance depends only on classical factors such as target-distracter similarity and distracter homogeneity, which we measured using simple searches. Across three experiments involving a variety of artificial and natural objects, differences between linearly separable and nonseparable searches were explained using target-distracter similarity and distracter heterogeneity. Further, simple searches accurately predicted complex search regardless of linear separability (r = 0.91). Our results show that complex search is explained by simple search, refuting the widely held belief that linear separability influences visual search. PMID:24029822
Hybridisations of Variable Neighbourhood Search and Modified Simplex Elements to Harmony Search and Shuffled Frog Leaping Algorithms for Process Optimisations

NASA Astrophysics Data System (ADS)

Aungkulanon, P.; Luangpaiboon, P.

2010-10-01

Nowadays, the engineering problem systems are large and complicated. An effective finite sequence of instructions for solving these problems can be categorised into optimisation and meta-heuristic algorithms. Though the best decision variable levels from some sets of available alternatives cannot be done, meta-heuristics is an alternative for experience-based techniques that rapidly help in problem solving, learning and discovery in the hope of obtaining a more efficient or more robust procedure. All meta-heuristics provide auxiliary procedures in terms of their own tooled box functions. It has been shown that the effectiveness of all meta-heuristics depends almost exclusively on these auxiliary functions. In fact, the auxiliary procedure from one can be implemented into other meta-heuristics. Well-known meta-heuristics of harmony search (HSA) and shuffled frog-leaping algorithms (SFLA) are compared with their hybridisations. HSA is used to produce a near optimal solution under a consideration of the perfect state of harmony of the improvisation process of musicians. A meta-heuristic of the SFLA, based on a population, is a cooperative search metaphor inspired by natural memetics. It includes elements of local search and global information exchange. This study presents solution procedures via constrained and unconstrained problems with different natures of single and multi peak surfaces including a curved ridge surface. Both meta-heuristics are modified via variable neighbourhood search method (VNSM) philosophy including a modified simplex method (MSM). The basic idea is the change of neighbourhoods during searching for a better solution. The hybridisations proceed by a descent method to a local minimum exploring then, systematically or at random, increasingly distant neighbourhoods of this local solution. The results show that the variant of HSA with VNSM and MSM seems to be better in terms of the mean and variance of design points and yields.
A Method for Search Engine Selection using Thesaurus for Selective Meta-Search Engine

NASA Astrophysics Data System (ADS)

Goto, Shoji; Ozono, Tadachika; Shintani, Toramatsu

In this paper, we propose a new method for selecting search engines on WWW for selective meta-search engine. In selective meta-search engine, a method is needed that would enable selecting appropriate search engines for users' queries. Most existing methods use statistical data such as document frequency. These methods may select inappropriate search engines if a query contains polysemous words. In this paper, we describe an search engine selection method based on thesaurus. In our method, a thesaurus is constructed from documents in a search engine and is used as a source description of the search engine. The form of a particular thesaurus depends on the documents used for its construction. Our method enables search engine selection by considering relationship between terms and overcomes the problems caused by polysemous words. Further, our method does not have a centralized broker maintaining data, such as document frequency for all search engines. As a result, it is easy to add a new search engine, and meta-search engines become more scalable with our method compared to other existing methods.
Task-Based Information Searching.

ERIC Educational Resources Information Center

Vakkari, Pertti

2003-01-01

Reviews studies on the relationship between task performance and information searching by end-users, focusing on information searching in electronic environments and information retrieval systems. Topics include task analysis; task characteristics; search goals; modeling information searching; modeling search goals; information seeking behavior;…
On the relationship between human search strategies, conspicuity, and search performance

NASA Astrophysics Data System (ADS)

Hogervorst, Maarten A.; Bijl, Piet; Toet, Alexander

2005-05-01

We determined the relationship between search performance with a limited field of view (FOV) and several scanning- and scene parameters in human observer experiments. The observers (38 trained army scouts) searched through a large search sector for a target (a camouflaged person) on a heath. From trial to trial the target appeared at a different location. With a joystick the observers scanned through a panoramic image (displayed on a PC-monitor) while the scan path was registered. Four conditions were run differing in sensor type (visual or thermal infrared) and window size (large or small). In conditions with a small window size the zoom option could be used. Detection performance was highly dependent on zoom factor and deteriorated when scan speed increased beyond a threshold value. Moreover, the distribution of scan speeds scales with the threshold speed. This indicates that the observers are aware of their limitations and choose a (near) optimal search strategy. We found no correlation between the fraction of detected targets and overall search time for the individual observers, indicating that both are independent measures of individual search performance. Search performance (fraction detected, total search time, time in view for detection) was found to be strongly related to target conspicuity. Moreover, we found the same relationship between search performance and conspicuity for visual and thermal targets. This indicates that search performance can be predicted directly by conspicuity regardless of the sensor type.
Search Fermilab Plant Database

Science.gov Websites

Select the characteristics of the plant you want to find below and click the Search button. To see Plants to see all the prairie plants in the database. Click Search All Plants at Fermilab to search for reflects observations at Fermilab. If you need a more sophisticated search, try the Advanced Search. Search
Stochastic Template Bank for Gravitational Wave Searches for Precessing Neutron Star-Black Hole Coalescence Events

NASA Technical Reports Server (NTRS)

Indik, Nathaniel; Haris, K.; Dal Canton, Tito; Fehrmann, Henning; Krishnan, Badri; Lundgren, Andrew; Nielsen, Alex B.; Pai, Archana

2017-01-01

Gravitational wave searches to date have largely focused on non-precessing systems. Including precession effects greatly increases the number of templates to be searched over. This leads to a corresponding increase in the computational cost and can increase the false alarm rate of a realistic search. On the other hand, there might be astrophysical systems that are entirely missed by non-precessing searches. In this paper we consider the problem of constructing a template bank using stochastic methods for neutron star-black hole binaries allowing for precession, but with the restrictions that the total angular momentum of the binary is pointing toward the detector and that the neutron star spin is negligible relative to that of the black hole. We quantify the number of templates required for the search, and we explicitly construct the template bank. We show that despite the large number of templates, stochastic methods can be adapted to solve the problem. We quantify the parameter space region over which the non-precessing search might miss signals.
Natural Language Search Interfaces: Health Data Needs Single-Field Variable Search.

PubMed

Jay, Caroline; Harper, Simon; Dunlop, Ian; Smith, Sam; Sufi, Shoaib; Goble, Carole; Buchan, Iain

2016-01-14

Data discovery, particularly the discovery of key variables and their inter-relationships, is key to secondary data analysis, and in-turn, the evolving field of data science. Interface designers have presumed that their users are domain experts, and so they have provided complex interfaces to support these "experts." Such interfaces hark back to a time when searches needed to be accurate first time as there was a high computational cost associated with each search. Our work is part of a governmental research initiative between the medical and social research funding bodies to improve the use of social data in medical research. The cross-disciplinary nature of data science can make no assumptions regarding the domain expertise of a particular scientist, whose interests may intersect multiple domains. Here we consider the common requirement for scientists to seek archived data for secondary analysis. This has more in common with search needs of the "Google generation" than with their single-domain, single-tool forebears. Our study compares a Google-like interface with traditional ways of searching for noncomplex health data in a data archive. Two user interfaces are evaluated for the same set of tasks in extracting data from surveys stored in the UK Data Archive (UKDA). One interface, Web search, is "Google-like," enabling users to browse, search for, and view metadata about study variables, whereas the other, traditional search, has standard multioption user interface. Using a comprehensive set of tasks with 20 volunteers, we found that the Web search interface met data discovery needs and expectations better than the traditional search. A task × interface repeated measures analysis showed a main effect indicating that answers found through the Web search interface were more likely to be correct (F1,19=37.3, P<.001), with a main effect of task (F3,57=6.3, P<.001). Further, participants completed the task significantly faster using the Web search interface (F1
Natural Language Search Interfaces: Health Data Needs Single-Field Variable Search

PubMed Central

Smith, Sam; Sufi, Shoaib; Goble, Carole; Buchan, Iain

2016-01-01

Background Data discovery, particularly the discovery of key variables and their inter-relationships, is key to secondary data analysis, and in-turn, the evolving field of data science. Interface designers have presumed that their users are domain experts, and so they have provided complex interfaces to support these “experts.” Such interfaces hark back to a time when searches needed to be accurate first time as there was a high computational cost associated with each search. Our work is part of a governmental research initiative between the medical and social research funding bodies to improve the use of social data in medical research. Objective The cross-disciplinary nature of data science can make no assumptions regarding the domain expertise of a particular scientist, whose interests may intersect multiple domains. Here we consider the common requirement for scientists to seek archived data for secondary analysis. This has more in common with search needs of the “Google generation” than with their single-domain, single-tool forebears. Our study compares a Google-like interface with traditional ways of searching for noncomplex health data in a data archive. Methods Two user interfaces are evaluated for the same set of tasks in extracting data from surveys stored in the UK Data Archive (UKDA). One interface, Web search, is “Google-like,” enabling users to browse, search for, and view metadata about study variables, whereas the other, traditional search, has standard multioption user interface. Results Using a comprehensive set of tasks with 20 volunteers, we found that the Web search interface met data discovery needs and expectations better than the traditional search. A task × interface repeated measures analysis showed a main effect indicating that answers found through the Web search interface were more likely to be correct (F 1,19=37.3, P<.001), with a main effect of task (F 3,57=6.3, P<.001). Further, participants completed the task
Phenomenological consequences of enhanced bulk viscosity near the QCD critical point

DOE PAGES

Monnai, Akihiko; Mukherjee, Swagato; Yin, Yi

2017-03-06

In the proximity of the QCD critical point the bulk viscosity of quark-gluon matter is expected to be proportional to nearly the third power of the critical correlation length, and become significantly enhanced. Here, this work is the first attempt to study the phenomenological consequences of enhanced bulk viscosity near the QCD critical point. For this purpose, we implement the expected critical behavior of the bulk viscosity within a non-boost-invariant, longitudinally expanding 1 + 1 dimensional causal relativistic hydrodynamical evolution at nonzero baryon density. We demonstrate that the critically enhanced bulk viscosity induces a substantial nonequilibrium pressure, effectively softening themore » equation of state, and leads to sizable effects in the flow velocity and single-particle distributions at the freeze-out. In conclusion, the observable effects that may arise due to the enhanced bulk viscosity in the vicinity of the QCD critical point can be used as complementary information to facilitate searches for the QCD critical point.« less
Field Simulation of a Drilling Mission to Mars to Search for Subsurface Life

NASA Technical Reports Server (NTRS)

Stoker, C. R.; Lemke, L. G.; Cannon, H.; Glass, B.; Dunagan, S.; Zavaleta, J.; Miller, D.; Gomez-Elvira, J.

2005-01-01

The discovery of near surface ground ice by the Mars Odyssey mission and the abundant evidence for recent Gulley features observed by the Mars Global Surveyor mission support longstanding theoretical arguments for subsurface liquid water on Mars. Thus, implementing the Mars program goal to search for life points to drilling on Mars to reach liquid water, collecting samples and analyzing them with instrumentation to detect in situ organisms and biomarker compounds. Searching for life in the subsurface of Mars will require drilling, sample extraction and handling, and new technologies to find and identify biomarker compounds and search for living organisms. In spite of its obvious advantages, robotic drilling for Mars exploration is in its technological infancy and has yet to be demonstrated in even a terrestrial field environment.
An instability of the standard model of cosmology creates the anomalous acceleration without dark energy

NASA Astrophysics Data System (ADS)

Smoller, Joel; Temple, Blake; Vogler, Zeke

2017-11-01

We identify the condition for smoothness at the centre of spherically symmetric solutions of Einstein's original equations without the cosmological constant or dark energy. We use this to derive a universal phase portrait which describes general, smooth, spherically symmetric solutions near the centre of symmetry when the pressure p=0. In this phase portrait, the critical k=0 Friedmann space-time appears as a saddle rest point which is unstable to spherical perturbations. This raises the question as to whether the Friedmann space-time is observable by redshift versus luminosity measurements looking outwards from any point. The unstable manifold of the saddle rest point corresponding to Friedmann describes the evolution of local uniformly expanding space-times whose accelerations closely mimic the effects of dark energy. A unique simple wave perturbation from the radiation epoch is shown to trigger the instability, match the accelerations of dark energy up to second order and distinguish the theory from dark energy at third order. In this sense, anomalous accelerations are not only consistent with Einstein's original theory of general relativity, but are a prediction of it without the cosmological constant or dark energy.
An instability of the standard model of cosmology creates the anomalous acceleration without dark energy.

PubMed

Smoller, Joel; Temple, Blake; Vogler, Zeke

2017-11-01

We identify the condition for smoothness at the centre of spherically symmetric solutions of Einstein's original equations without the cosmological constant or dark energy. We use this to derive a universal phase portrait which describes general, smooth, spherically symmetric solutions near the centre of symmetry when the pressure p =0. In this phase portrait, the critical k =0 Friedmann space-time appears as a saddle rest point which is unstable to spherical perturbations. This raises the question as to whether the Friedmann space-time is observable by redshift versus luminosity measurements looking outwards from any point. The unstable manifold of the saddle rest point corresponding to Friedmann describes the evolution of local uniformly expanding space-times whose accelerations closely mimic the effects of dark energy. A unique simple wave perturbation from the radiation epoch is shown to trigger the instability, match the accelerations of dark energy up to second order and distinguish the theory from dark energy at third order. In this sense, anomalous accelerations are not only consistent with Einstein's original theory of general relativity, but are a prediction of it without the cosmological constant or dark energy.
BioEve Search: A Novel Framework to Facilitate Interactive Literature Search

PubMed Central

Ahmed, Syed Toufeeq; Davulcu, Hasan; Tikves, Sukru; Nair, Radhika; Zhao, Zhongming

2012-01-01

Background. Recent advances in computational and biological methods in last two decades have remarkably changed the scale of biomedical research and with it began the unprecedented growth in both the production of biomedical data and amount of published literature discussing it. An automated extraction system coupled with a cognitive search and navigation service over these document collections would not only save time and effort, but also pave the way to discover hitherto unknown information implicitly conveyed in the texts. Results. We developed a novel framework (named “BioEve”) that seamlessly integrates Faceted Search (Information Retrieval) with Information Extraction module to provide an interactive search experience for the researchers in life sciences. It enables guided step-by-step search query refinement, by suggesting concepts and entities (like genes, drugs, and diseases) to quickly filter and modify search direction, and thereby facilitating an enriched paradigm where user can discover related concepts and keywords to search while information seeking. Conclusions. The BioEve Search framework makes it easier to enable scalable interactive search over large collection of textual articles and to discover knowledge hidden in thousands of biomedical literature articles with ease. PMID:22693501

Optimal Number and Allocation of Data Collection Points for Linear Spline Growth Curve Modeling: A Search for Efficient Designs

ERIC Educational Resources Information Center

Wu, Wei; Jia, Fan; Kinai, Richard; Little, Todd D.

2017-01-01

Spline growth modelling is a popular tool to model change processes with distinct phases and change points in longitudinal studies. Focusing on linear spline growth models with two phases and a fixed change point (the transition point from one phase to the other), we detail how to find optimal data collection designs that maximize the efficiency…
Folksonomical P2P File Sharing Networks Using Vectorized KANSEI Information as Search Tags

NASA Astrophysics Data System (ADS)

Ohnishi, Kei; Yoshida, Kaori; Oie, Yuji

We present the concept of folksonomical peer-to-peer (P2P) file sharing networks that allow participants (peers) to freely assign structured search tags to files. These networks are similar to folksonomies in the present Web from the point of view that users assign search tags to information distributed over a network. As a concrete example, we consider an unstructured P2P network using vectorized Kansei (human sensitivity) information as structured search tags for file search. Vectorized Kansei information as search tags indicates what participants feel about their files and is assigned by the participant to each of their files. A search query also has the same form of search tags and indicates what participants want to feel about files that they will eventually obtain. A method that enables file search using vectorized Kansei information is the Kansei query-forwarding method, which probabilistically propagates a search query to peers that are likely to hold more files having search tags that are similar to the query. The similarity between the search query and the search tags is measured in terms of their dot product. The simulation experiments examine if the Kansei query-forwarding method can provide equal search performance for all peers in a network in which only the Kansei information and the tendency with respect to file collection are different among all of the peers. The simulation results show that the Kansei query forwarding method and a random-walk-based query forwarding method, for comparison, work effectively in different situations and are complementary. Furthermore, the Kansei query forwarding method is shown, through simulations, to be superior to or equal to the random-walk based one in terms of search speed.
Analytic Guided-Search Model of Human Performance Accuracy in Target- Localization Search Tasks

NASA Technical Reports Server (NTRS)

Eckstein, Miguel P.; Beutter, Brent R.; Stone, Leland S.

2000-01-01

Current models of human visual search have extended the traditional serial/parallel search dichotomy. Two successful models for predicting human visual search are the Guided Search model and the Signal Detection Theory model. Although these models are inherently different, it has been difficult to compare them because the Guided Search model is designed to predict response time, while Signal Detection Theory models are designed to predict performance accuracy. Moreover, current implementations of the Guided Search model require the use of Monte-Carlo simulations, a method that makes fitting the model's performance quantitatively to human data more computationally time consuming. We have extended the Guided Search model to predict human accuracy in target-localization search tasks. We have also developed analytic expressions that simplify simulation of the model to the evaluation of a small set of equations using only three free parameters. This new implementation and extension of the Guided Search model will enable direct quantitative comparisons with human performance in target-localization search experiments and with the predictions of Signal Detection Theory and other search accuracy models.
Effects of contour enhancement on low-vision preference and visual search.

PubMed

Satgunam, Premnandhini; Woods, Russell L; Luo, Gang; Bronstad, P Matthew; Reynolds, Zachary; Ramachandra, Chaithanya; Mel, Bartlett W; Peli, Eli

2012-09-01

To determine whether image enhancement improves visual search performance and whether enhanced images were also preferred by subjects with vision impairment. Subjects (n = 24) with vision impairment (vision: 20/52 to 20/240) completed visual search and preference tasks for 150 static images that were enhanced to increase object contours' visual saliency. Subjects were divided into two groups and were shown three enhancement levels. Original and medium enhancements were shown to both groups. High enhancement was shown to group 1, and low enhancement was shown to group 2. For search, subjects pointed to an object that matched a search target displayed at the top left of the screen. An "integrated search performance" measure (area under the curve of cumulative correct response rate over search time) quantified performance. For preference, subjects indicated the preferred side when viewing the same image with different enhancement levels on side-by-side high-definition televisions. Contour enhancement did not improve performance in the visual search task. Group 1 subjects significantly (p < 0.001) rejected the High enhancement, and showed no preference for medium enhancement over the original images. Group 2 subjects significantly preferred (p < 0.001) both the medium and the low enhancement levels over original. Contrast sensitivity was correlated with both preference and performance; subjects with worse contrast sensitivity performed worse in the search task (ρ = 0.77, p < 0.001) and preferred more enhancement (ρ = -0.47, p = 0.02). No correlation between visual search performance and enhancement preference was found. However, a small group of subjects (n = 6) in a narrow range of mid-contrast sensitivity performed better with the enhancement, and most (n = 5) also preferred the enhancement. Preferences for image enhancement can be dissociated from search performance in people with vision impairment. Further investigations are needed to study the relationships
Beyond MEDLINE for literature searches.

PubMed

Conn, Vicki S; Isaramalai, Sang-arun; Rath, Sabyasachi; Jantarakupt, Peeranuch; Wadhawan, Rohini; Dash, Yashodhara

2003-01-01

To describe strategies for a comprehensive literature search. MEDLINE searches result in limited numbers of studies that are often biased toward statistically significant findings. Diversified search strategies are needed. Empirical evidence about the recall and precision of diverse search strategies is presented. Challenges and strengths of each search strategy are identified. Search strategies vary in recall and precision. Often sensitivity and specificity are inversely related. Valuable search strategies include examination of multiple diverse computerized databases, ancestry searches, citation index searches, examination of research registries, journal hand searching, contact with the "invisible college," examination of abstracts, Internet searches, and contact with sources of synthesized information. Extending searches beyond MEDLINE enables researchers to conduct more systematic comprehensive searches.
Conjunction search revisited.

PubMed

Treisman, A; Sato, S

1990-08-01

Search for conjunctions of highly discriminable features can be rapid or even parallel. This article explores three possible accounts based on (a) perceptual segregation, (b) conjunction detectors, and (c) inhibition controlled separately by two or more distractor features. Search rates for conjunctions of color, size, orientation, and direction of motion correlated closely with an independent measure of perceptual segregation. However, they appeared unrelated to the physiology of single-unit responses. Each dimension contributed additively to conjunction search rates, suggesting that each was checked independently of the others. Unknown targets appear to be found only by serial search for each in turn. Searching through 4 sets of distractors was slower than searching through 2. The results suggest a modification of feature integration theory, in which attention is controlled not only by a unitary "window" but also by a form of feature-based inhibition.
Search Term Reports

EPA Pesticide Factsheets

Learn what search terms brought users to choose your page in their search results, and what terms they entered in the EPA search box after visiting your page. Use this information to improve links and content on the page.
Parallel Monte Carlo Search for Hough Transform

NASA Astrophysics Data System (ADS)

Lopes, Raul H. C.; Franqueira, Virginia N. L.; Reid, Ivan D.; Hobson, Peter R.

2017-10-01

We investigate the problem of line detection in digital image processing and in special how state of the art algorithms behave in the presence of noise and whether CPU efficiency can be improved by the combination of a Monte Carlo Tree Search, hierarchical space decomposition, and parallel computing. The starting point of the investigation is the method introduced in 1962 by Paul Hough for detecting lines in binary images. Extended in the 1970s to the detection of space forms, what came to be known as Hough Transform (HT) has been proposed, for example, in the context of track fitting in the LHC ATLAS and CMS projects. The Hough Transform transfers the problem of line detection, for example, into one of optimization of the peak in a vote counting process for cells which contain the possible points of candidate lines. The detection algorithm can be computationally expensive both in the demands made upon the processor and on memory. Additionally, it can have a reduced effectiveness in detection in the presence of noise. Our first contribution consists in an evaluation of the use of a variation of the Radon Transform as a form of improving theeffectiveness of line detection in the presence of noise. Then, parallel algorithms for variations of the Hough Transform and the Radon Transform for line detection are introduced. An algorithm for Parallel Monte Carlo Search applied to line detection is also introduced. Their algorithmic complexities are discussed. Finally, implementations on multi-GPU and multicore architectures are discussed.
AN ARECIBO SEARCH FOR PULSARS AND TRANSIENT SOURCES IN M33

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

Bhat, N. D. R.; Cox, P. J.; Cordes, J. M.

We report on a systematic and sensitive search for pulsars and transient sources in the nearby spiral galaxy M33, conducted at 1.4 GHz with the Arecibo telescope's seven-beam receiver system, ALFA. Data were searched for both periodic and aperiodic sources, up to 1000 pc cm{sup -3} in dispersion measure and on timescales from {approx}50 {mu}s to several seconds. The galaxy was sampled with 12 ALFA pointings, or 84 pixels in total, each of which was searched for 2-3 hr. We describe the observations, search methodologies, and analysis strategies applicable to multibeam systems, and comment on the data quality and statisticsmore » of spurious events that arise due to radio frequency interference. While these searches have not led to any conclusive signals of periodic or transient nature that originate in the galaxy, they illustrate some of the underlying challenges and difficulties in such searches and the efficacy of simultaneous multiple beams in the analysis of search output. The implied limits are {approx}<5 {mu}Jy Mpc{sup 2} in luminosity (at 1400 MHz) for periodic sources in M33 with duty cycles {approx}<5%. For short-duration transient signals (with pulse widths {approx}<100 {mu}s ), the limiting peak flux density is 100 mJy, which would correspond to a 5{sigma} detection of bright giant pulses ({approx}20 kJy) from Crab-like pulsars if located at the distance of M33. We discuss the implications of our null results for various source populations within the galaxy and comment on the future prospects to conduct even more sensitive searches with the upcoming next-generation instruments including the Square Kilometer Array and its pathfinders.« less
Point-of-Care Hemoglobin A1c Testing: An Evidence-Based Analysis

PubMed Central

2014-01-01

Background The increasing prevalence of diabetes in Ontario means that there will be growing demand for hemoglobin A1c (HbA1c) testing to monitor glycemic control for the management of this chronic disease. Testing HbA1c where patients receive their diabetes care may improve system efficiency if the results from point-of-care HbA1c testing are comparable to those from laboratory HbA1c measurements. Objectives To review the correlation between point-of-care HbA1c testing and laboratory HbA1c measurement in patients with diabetes in clinical settings. Data Sources The literature search included studies published between January 2003 and June 2013. Search terms included glycohemoglobin, hemoglobin A1c, point of care, and diabetes. Review Methods Studies were included if participants had diabetes; if they compared point-of-care HbA1c devices (licensed by Health Canada and available in Canada) with laboratory HbA1c measurement (reference method); if they performed point-of-care HbA1c testing using capillary blood samples (finger pricks) and laboratory HbA1c measurement using venous blood samples within 7 days; and if they reported a correlation coefficient between point-of-care HbA1c and laboratory HbA1c results. Results Three point-of-care HbA1c devices were reviewed in this analysis: Bayer's A1cNow+, Bio-Rad's In2it, and Siemens’ DCA Vantage. Five observational studies met the inclusion criteria. The pooled results showed a positive correlation between point-of-care HbA1c testing and laboratory HbA1c measurement (correlation coefficient, 0.967; 95% confidence interval, 0.960–0.973). Limitations Outcomes were limited to the correlation coefficient, as this was a commonly reported measure of analytical performance in the literature. Results should be interpreted with caution due to risk of bias related to selection of participants, reference standards, and the multiple steps involved in POC HbA1c testing. Conclusions Moderate quality evidence showed a positive
Second stop and sbottom searches with a stealth stop

NASA Astrophysics Data System (ADS)

Cheng, Hsin-Chia; Li, Lingfeng; Qin, Qin

2016-11-01

The top squarks (stops) may be the most wanted particles after the Higgs boson discovery. The searches for the lightest stop have put strong constraints on its mass. However, there is still a search gap in the low mass region if the spectrum of the stop and the lightest neutralino is compressed. In that case, it may be easier to look for the second stop since naturalness requires both stops to be close to the weak scale. The current experimental searches for the second stop are based on the simplified model approach with the decay modes {overset{˜ }{t}}_2to {overset{˜ }{t}}_1Z and {overset{˜ }{t}}_2to {overset{˜ }{t}}_1h . However, in a realistic supersymmetric spectrum there is always a sbottom lighter than the second stop, hence the decay patterns are usually more complicated than the simplified model assumptions. In particular, there are often large branching ratios of the decays {overset{˜ }{t}}_2to {overset{˜ }{b}}_1W and {overset{˜ }{b}}_1to {overset{˜ }{t}}_1W as long as they are open. The decay chains can be even more complex if there are intermediate states of additional charginos and neutralinos in the decays. By studying several MSSM benchmark models at the 14 TeV LHC, we point out the importance of the multi- W final states in the second stop and the sbottom searches, such as the same-sign dilepton and multilepton signals, aside from the traditional search modes. The observed same-sign dilepton excesses at LHC Run 1 and Run 2 may be explained by some of our benchmark models. We also suggest that the vector boson tagging and a new kinematic variable may help to suppress the backgrounds and increase the signal significance for some search channels. Due to the complex decay patterns and lack of the dominant decay channels, the best reaches likely require a combination of various search channels at the LHC for the second stop and the lightest sbottom.
A complex fermionic tensor model in d dimensions

NASA Astrophysics Data System (ADS)

Prakash, Shiroman; Sinha, Ritam

2018-02-01

In this note, we study a melonic tensor model in d dimensions based on three-index Dirac fermions with a four-fermion interaction. Summing the melonic diagrams at strong coupling allows one to define a formal large- N saddle point in arbitrary d and calculate the spectrum of scalar bilinear singlet operators. For d = 2 - ɛ the theory is an infrared fixed point, which we find has a purely real spectrum that we determine numerically for arbitrary d < 2, and analytically as a power series in ɛ. The theory appears to be weakly interacting when ɛ is small, suggesting that fermionic tensor models in 1-dimension can be studied in an ɛ expansion. For d > 2, the spectrum can still be calculated using the saddle point equations, which may define a formal large- N ultraviolet fixed point analogous to the Gross-Neveu model in d > 2. For 2 < d < 6, we find that the spectrum contains at least one complex scalar eigenvalue (similar to the complex eigenvalue present in the bosonic tensor model recently studied by Giombi, Klebanov and Tarnopolsky) which indicates that the theory is unstable. We also find that the fixed point is weakly-interacting when d = 6 (or more generally d = 4 n + 2) and has a real spectrum for 6 < d < 6 .14 which we present as a power series in ɛ in 6 + ɛ dimensions.
BioSearch: a semantic search engine for Bio2RDF

PubMed Central

Qiu, Honglei; Huang, Jiacheng

2017-01-01

Abstract Biomedical data are growing at an incredible pace and require substantial expertise to organize data in a manner that makes them easily findable, accessible, interoperable and reusable. Massive effort has been devoted to using Semantic Web standards and technologies to create a network of Linked Data for the life sciences, among others. However, while these data are accessible through programmatic means, effective user interfaces for non-experts to SPARQL endpoints are few and far between. Contributing to user frustrations is that data are not necessarily described using common vocabularies, thereby making it difficult to aggregate results, especially when distributed across multiple SPARQL endpoints. We propose BioSearch — a semantic search engine that uses ontologies to enhance federated query construction and organize search results. BioSearch also features a simplified query interface that allows users to optionally filter their keywords according to classes, properties and datasets. User evaluation demonstrated that BioSearch is more effective and usable than two state of the art search and browsing solutions. Database URL: http://ws.nju.edu.cn/biosearch/ PMID:29220451
Construction of nested maximin designs based on successive local enumeration and modified novel global harmony search algorithm

NASA Astrophysics Data System (ADS)

Yi, Jin; Li, Xinyu; Xiao, Mi; Xu, Junnan; Zhang, Lin

2017-01-01

Engineering design often involves different types of simulation, which results in expensive computational costs. Variable fidelity approximation-based design optimization approaches can realize effective simulation and efficiency optimization of the design space using approximation models with different levels of fidelity and have been widely used in different fields. As the foundations of variable fidelity approximation models, the selection of sample points of variable-fidelity approximation, called nested designs, is essential. In this article a novel nested maximin Latin hypercube design is constructed based on successive local enumeration and a modified novel global harmony search algorithm. In the proposed nested designs, successive local enumeration is employed to select sample points for a low-fidelity model, whereas the modified novel global harmony search algorithm is employed to select sample points for a high-fidelity model. A comparative study with multiple criteria and an engineering application are employed to verify the efficiency of the proposed nested designs approach.
Hierarchical clustering of EMD based interest points for road sign detection

NASA Astrophysics Data System (ADS)

Khan, Jesmin; Bhuiyan, Sharif; Adhami, Reza

2014-04-01

This paper presents an automatic road traffic signs detection and recognition system based on hierarchical clustering of interest points and joint transform correlation. The proposed algorithm consists of the three following stages: interest points detection, clustering of those points and similarity search. At the first stage, good discriminative, rotation and scale invariant interest points are selected from the image edges based on the 1-D empirical mode decomposition (EMD). We propose a two-step unsupervised clustering technique, which is adaptive and based on two criterion. In this context, the detected points are initially clustered based on the stable local features related to the brightness and color, which are extracted using Gabor filter. Then points belonging to each partition are reclustered depending on the dispersion of the points in the initial cluster using position feature. This two-step hierarchical clustering yields the possible candidate road signs or the region of interests (ROIs). Finally, a fringe-adjusted joint transform correlation (JTC) technique is used for matching the unknown signs with the existing known reference road signs stored in the database. The presented framework provides a novel way to detect a road sign from the natural scenes and the results demonstrate the efficacy of the proposed technique, which yields a very low false hit rate.
When is a search not a search? A comparison of searching the AMED complementary health database via EBSCOhost, OVID and DIALOG.

PubMed

Younger, Paula; Boddy, Kate

2009-06-01

The researchers involved in this study work at Exeter Health library and at the Complementary Medicine Unit, Peninsula School of Medicine and Dentistry (PCMD). Within this collaborative environment it is possible to access the electronic resources of three institutions. This includes access to AMED and other databases using different interfaces. The aim of this study was to investigate whether searching different interfaces to the AMED allied health and complementary medicine database produced the same results when using identical search terms. The following Internet-based AMED interfaces were searched: DIALOG DataStar; EBSCOhost and OVID SP_UI01.00.02. Search results from all three databases were saved in an endnote database to facilitate analysis. A checklist was also compiled comparing interface features. In our initial search, DIALOG returned 29 hits, OVID 14 and Ebsco 8. If we assume that DIALOG returned 100% of potential hits, OVID initially returned only 48% of hits and EBSCOhost only 28%. In our search, a researcher using the Ebsco interface to carry out a simple search on AMED would miss over 70% of possible search hits. Subsequent EBSCOhost searches on different subjects failed to find between 21 and 86% of the hits retrieved using the same keywords via DIALOG DataStar. In two cases, the simple EBSCOhost search failed to find any of the results found via DIALOG DataStar. Depending on the interface, the number of hits retrieved from the same database with the same simple search can vary dramatically. Some simple searches fail to retrieve a substantial percentage of citations. This may result in an uninformed literature review, research funding application or treatment intervention. In addition to ensuring that keywords, spelling and medical subject headings (MeSH) accurately reflect the nature of the search, database users should include wildcards and truncation and adapt their search strategy substantially to retrieve the maximum number of appropriate
The Effects of Hydrogen on the Potential-Energy Surface of Amorphous Silicon

NASA Astrophysics Data System (ADS)

Joly, Jean-Francois; Mousseau, Normand

2012-02-01

Hydrogenated amorphous silicon (a-Si:H) is an important semiconducting material used in many applications from solar cells to transistors. In 2010, Houssem et al. [1], using the open-ended saddle-point search method, ART nouveau, studied the characteristics of the potential energy landscape of a-Si as a function of relaxation. Here, we extend this study and follow the impact of hydrogen doping on the same a-Si models as a function of doping level. Hydrogen atoms are first attached to dangling bonds, then are positioned to relieve strained bonds of fivefold coordinated silicon atoms. Once these sites are saturated, further doping is achieved with a Monte-Carlo bond switching method that preserves coordination and reduces stress [2]. Bonded interactions are described with a modified Stillinger-Weber potential and non-bonded Si-H and H-H interactions with an adapted Slater-Buckingham potential. Large series of ART nouveau searches are initiated on each model, resulting in an extended catalogue of events that characterize the evolution of potential energy surface as a function of H-doping. [4pt] [1] Houssem et al., Phys Rev. Lett., 105, 045503 (2010)[0pt] [2] Mousseau et al., Phys Rev. B, 41, 3702 (1990)
Web Search Studies: Multidisciplinary Perspectives on Web Search Engines

NASA Astrophysics Data System (ADS)

Zimmer, Michael

Perhaps the most significant tool of our internet age is the web search engine, providing a powerful interface for accessing the vast amount of information available on the world wide web and beyond. While still in its infancy compared to the knowledge tools that precede it - such as the dictionary or encyclopedia - the impact of web search engines on society and culture has already received considerable attention from a variety of academic disciplines and perspectives. This article aims to organize a meta-discipline of “web search studies,” centered around a nucleus of major research on web search engines from five key perspectives: technical foundations and evaluations; transaction log analyses; user studies; political, ethical, and cultural critiques; and legal and policy analyses.
Prepare for the Job Search. Job Search. Competency 1.0.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

This competency booklet for individualized competency-based instruction is the first of five in the Job Search Skills package. (Instructor program and guides are available separately as CE 031 965 and 966, the other booklets as CE 031 968-971.) It contains 15 operational units related to the job search competency of preparing for the job search.…
Attention parameters in visual search tasks in different age groups.

PubMed

Baranov-Krylov, I N; Kuznetsova, T G; Ratnikova, V K

2009-06-01

Attention processes were studied using a model based on visual searches for a specified element in grids of size 3 x 3 and 7 x 7 cm displayed on a monitor screen. Five age groups took part in the experimental studies: children of five and seven years, a group of 15-year-old adolescents, a group aged 20-35 years, and a group aged over 60 years; a total of 62 subjects took part. Statistical analysis showed that the latter three groups were not different from each other and were used as an adult control group for comparison with results from children. Five types of search were used: one difficult, in which the target was similar to the distractors, and four easy (for adults but not for children), involving seeking a red or a white element in an empty grid and seeking a target markedly different in shape or color from the distractors. The following measures were analyzed: search time, errors (false alarms and misses), and corrected search times allowing for errors. Children performed significantly worse on all measures: they found all types of search difficult, even the search for a single element. The larger number of false alarms (reactions to nonmeaningful signals) was evidence for a deficiency of inhibitory processes in children, these being controlled by the frontal lobes. The larger number of misses in children may be evidence of weakness of selective attention, which is controlled by the parietal and temporal areas of the cortex. These points may indicate that children have an immature attention system, though this would appear to mature completely by age 15 years.

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