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1

Electrodynamic forces of the cross-connected figure-eight null-flux coil suspension system  

SciTech Connect

This paper analyzes the cross-connected figure-eight null-flux coil suspension system for maglev vehicles on the basis of dynamic circuit theory. The equivalent circuits and general magnetic force expressions for the system are developed. Simple analytical formulas for the magnetic force partitions on the basis of harmonic approximation are presented, and numerical results are also included.

He, J.L.; Rote, D.M.; Coffey, H.T.

1993-06-01

2

Electrodynamic forces of the cross-connected figure-eight null-flux coil suspension system  

SciTech Connect

This paper analyzes the cross-connected figure-eight null-flux coil suspension system for maglev vehicles on the basis of dynamic circuit theory. The equivalent circuits and general magnetic force expressions for the system are developed. Simple analytical formulas for the magnetic force partitions on the basis of harmonic approximation are presented, and numerical results are also included.

He, J.L.; Rote, D.M.; Coffey, H.T.

1993-01-01

3

Magnetic damping forces in figure-eight-shaped null-flux coil suspension systems  

SciTech Connect

This paper discusses magnetic damping forces in figure-eight-shaped null-flux coil suspension systems, focusing on the Holloman maglev rocket system. The paper also discusses simulating the damping plate, which is attached to the superconducting magnet by two short-circuited loop coils in the guideway. Closed-form formulas for the magnetic damping coefficient as functions of heave-and-sway displacements are derived by using a dynamic circuit model. These formulas are useful for dynamic stability studies.

He, Jianliang; Coffey, H.

1997-08-01

4

Study on figure-eight-shaped coil electrodynamic suspension magnetic levitation systems without cross-connection  

SciTech Connect

Two figure-eight-shaped coils for electrodynamic suspension (EDS) magnetic levitation (MAGLEV) systems without cross-connection are proposed and analyzed. The guideway coils are positioned under the MAGLEV vehicle; they are parallel to the horizontal plane. The interaction of a magnetic module on the vehicle, composed of three or four superconducting (SC) coils, with a guideway module, comprised of two figure-eight coils, is studied by means of the dynamic circuit theory. The currents in the SC coils are supposed to be constant in time while they move as a rigid body, with a constant velocity. Some results are presented and compared with those for a standard side-wall cross-connected system.

Ribani, P.L.; Urbano, N.

2000-01-01

5

Magnet Correction by Figure Eights  

Microsoft Academic Search

''Figure eights'' - superconducting loops with a figure eight geometry - provide an automatic, passive method for improving the field uniformity of superconducting dipole magnets. Figure eights are especially well suited for correcting iron-dominated dipoles operating at three tesla, where saturation of the iron makes it difficult to maintain acceptable field uniformity over the full operating range. By using figure

J. Purcell; W. Chen; A. Peuron

1985-01-01

6

Forces on a magnet moving past figure-eight coils  

SciTech Connect

Considerable attention has been given to the magnetic levitation of vehicles over guideways consisting of periodically-spaced conducting coils. Examples of proposed guideway configurations include arrays of independent coils (''loop track''), interconnected coils (''ladder track''), two layers of coils (double-layer ''null-flux'' track), and figure-eight coils (single-layer ''null-flux'' track). Typically, widely-separated superconducting magnets are mounted in the vehicle. A system that achieves both lift and guidance from vertical figure-eight coils in the guideway sidewalls has been developed in Japan. This system, when well designed, can have a very large lift-to-drag ratio. The authors conducted an experimental and theoretical investigation of the lift, drag, and guidance forces on a permanent magnet moving close to various arrays of figure-eight coils. The measured time-histories of the forces provide a basis for the evaluation of electrodynamic models and codes developed to analyze the magnetic levitation of vehicles using the discrete suspension coils of the null-flux type. Good correlation was found between the experimental data and the predictions of the code COIL GDWY. The authors report some of the results and discuss their application to the design of maglev systems.

Mulcahy, T.M.; He, J.; Rote, D.M. (Argonne National Lab., IL (United States)); Rossing, T.D. (Northern Illinois Univ., De Kalb, IL (United States). Dept. of Physics)

1993-11-01

7

Designing with null flux coils  

SciTech Connect

Null flux were suggested by Danby and Powell in the late 1960`s as a useful means for realizing induced lift with little drag. As an array of alternating magnets is translated past a set of null flux coils, the currents induced in these coils act to vertically center the magnets on those coils. At present, one Japanese MAGLEV system company and two American-based companies are employing either null flux or flux eliminating coils in their design for high speed magnetically levitated transportation. The principle question addressed in paper is: what is the proper choice of coil length to magnet length in a null flux system? A generic analysis in the time and frequency domain is laid out with the intent of showing the optimal design specification in terms of coil parameters.

Davey, K.R. [American Electromechanics, New Smyrna Beach, FL (United States)] [American Electromechanics, New Smyrna Beach, FL (United States)

1997-09-01

8

78 FR 25577 - Safety Zone, Figure Eight Causeway Channel; Figure Eight Island, NC  

Federal Register 2010, 2011, 2012, 2013

...Island, NC in support of the fireworks display for a private wedding. This action is necessary to protect the life and property...Pyrotechnics will provide a fireworks display in support of a private wedding over the waters of the Figure Eight Causeway Channel....

2013-05-02

9

Homochiral and meso Figure Eight Knots and a Solomon Link.  

PubMed

A homochiral naphthalenediimide-based building block forms in water a disulfide library of macrocycles containing topological isomers. We attempted to identify each of these isomers, and explored the mechanisms leading to their formation. The two most abundant species of the library were assigned as a topologically chiral Solomon link (60% of the library, as measured by high-performance liquid chromatography (HPLC)) and a topologically achiral figure eight knot (18% by HPLC), competing products with formally different geometries but remarkably similar 4-fold symmetries. In contrast, a racemic mixture of building blocks gives the near-quantitative formation of another new and more stable structure, assigned as a meso figure eight knot. Taken together, these results seem to uncover a correlation between the point chirality of the building block used and the topological chirality of the major structure formed. These and the earlier discovery of a trefoil knot also suggest that the number of rigid components in the building block may translate into corresponding knot symmetry and could set the basis of a new strategy for constructing complex topologies. PMID:24831779

Ponnuswamy, Nandhini; Cougnon, Fabien B L; Panto?, G Dan; Sanders, Jeremy K M

2014-06-11

10

A polarization maintaining, dispersion managed, femtosecond figure-eight fiber laser  

Microsoft Academic Search

We demonstrate a polarization maintaining, figure-eight erbium-doped fiber laser with a dispersion managed cavity. The laser was passively modelocked and produced pulses that were de-chirped to 427 fs pulses outside the laser cavity. An intra-cavity amplitude modulator was used to initiate the pulses, but the modulator was turned off during femtosecond pulse operation.

J. W. Nicholson; M. Andrejco

2006-01-01

11

DEVELOPMENT OF LOCOMOTOR ACTIVITY OF RAT PUPS IN FIGURE-EIGHT MAZES  

EPA Science Inventory

In a series of four experiments, social and experiential factors that influence the development of motor activity in rat pups were examined. Motor activity was monitored from postnatal days 13 to 21 as photocell interruptions in figure-eight mazes and comparisons were made betwee...

12

Dual-wavelength operation of a figure-eight fiber laser  

NASA Astrophysics Data System (ADS)

We study numerically an erbium-doped figure-eight fiber laser including a double-band-pass optical filter for dual-wavelength pulse generation. Simulations are performed for several values of the filter band-width and wavelength separation between the transmission windows. The results show that dual-wavelength mode-locking is obtained in most cases, with a balanced energy distribution between wavelengths. Due to cavity dispersion, the pulses at each wavelength are asynchronous for a large wavelength separation, whereas they are synchronous for closely spaced wavelengths, as in this case cross-phase modulation is able to compensate for the dispersion-induced walkoff. In the asynchronous case, dual-wavelength operation is favored by the filter loss, whereas in the synchronous case it is favored by the saturable absorber action of the nonlinear optical loop mirror. Simulations also show that, thanks to those stabilization mechanisms, dual-wave-length pulsed operation does not require precise cavity loss equalization between the two oscillating wave-lengths.

Pottiez, O.; Hernandez-Garcia, J. C.; Ibarra-Escamilla, B.; Kuzin, E. A.

2012-10-01

13

Richness of dynamics and global bifurcations in systems with a homoclinic figure-eight  

NASA Astrophysics Data System (ADS)

We consider 2D flows with a homoclinic figure-eight to a dissipative saddle. We study the rich dynamics that such a system exhibits under a periodic forcing. First, we derive the bifurcation diagram using topological techniques. In particular, there is a homoclinic zone in the parameter space with a non-smooth boundary. We provide a complete explanation of this phenomenon relating it to primary quadratic homoclinic tangency curves which end up at some cubic tangency (cusp) points. We also describe the possible attractors that exist (and may coexist) in the system. A main goal of this work is to show how the previous qualitative description can be complemented with quantitative global information. To this end, we introduce a return map model which can be seen as the simplest one which is ‘universal’ in some sense. We carry out several numerical experiments on the model, to check that all the objects predicted to exist by the theory are found in the model, and also to investigate new properties of the system. Dedicated to the memory of Leonid Pavlovich Shilnikov, a Master whose works strongly influenced the mathematical theory of dynamical systems.

Gonchenko, S. V.; Simó, C.; Vieiro, A.

2013-03-01

14

Generation of ultra short pulses in a figure-eight fiber laser using microstructured optical fiber MOF  

Microsoft Academic Search

Figure-eight fiber laser (8FL), as a source of ultra short pulses find many applications in optical communication. In this paper, we provide basic ideas about principle of operation of this type of fiber laser. We also give an idea about the Split Step Fourier Method (SSFM) and we use this algorithm to simulate our application. As much as we can,

Tarek Ennejah; Faouzi Bahloul; Rabah Attia

2007-01-01

15

Computer model simulation of null-flux magnetic suspension and guidance  

SciTech Connect

This paper discusses the magnetic force computations in a null-flux suspension system using dynamic circuit theory. A computer simulation model that can be used to compute magnetic forces and predict the system performance is developed on the basis of dynamic circuit theory. Numerical examples are presented to demonstrate the application of the model. The performance of the null-flux suspension system is simulated and discussed. 8 refs.

He, Jianliang; Rote, D.M.

1992-06-01

16

Computer model simulation of null-flux magnetic suspension and guidance  

SciTech Connect

This paper discusses the magnetic force computations in a null-flux suspension system using dynamic circuit theory. A computer simulation model that can be used to compute magnetic forces and predict the system performance is developed on the basis of dynamic circuit theory. Numerical examples are presented to demonstrate the application of the model. The performance of the null-flux suspension system is simulated and discussed. 8 refs.

He, Jianliang; Rote, D.M.

1992-01-01

17

Vector nature of multi-soliton patterns in a passively mode-locked figure-eight fiber laser.  

PubMed

The vector nature of multi-soliton dynamic patterns was investigated in a passively mode-locked figure-eight fiber laser based on the nonlinear amplifying loop mirror (NALM). By properly adjusting the cavity parameters such as the pump power level and intra-cavity polarization controllers (PCs), in addition to the fundamental vector soliton, various vector multi-soliton regimes were observed, such as the random static distribution of vector multiple solitons, vector soliton cluster, vector soliton flow, and the state of vector multiple solitons occupying the whole cavity. Both the polarization-locked vector solitons (PLVSs) and the polarization-rotating vector solitons (PRVSs) were observed for fundamental soliton and each type of multi-soliton patterns. The obtained results further reveal the fundamental physics of multi-soliton patterns and demonstrate that the figure-eight fiber lasers are indeed a good platform for investigating the vector nature of different soliton types. PMID:24921311

Ning, Qiu-Yi; Liu, Hao; Zheng, Xu-Wu; Yu, Wei; Luo, Ai-Ping; Huang, Xu-Guang; Luo, Zhi-Chao; Xu, Wen-Cheng; Xu, Shan-Hui; Yang, Zhong-Min

2014-05-19

18

Observation of dual-wavelength dissipative solitons in a figure-eight erbium-doped fiber laser.  

PubMed

We report on the generation of dual-wavelength dissipative solitons (DSs) in a passively mode-locked figure-eight fiber laser operating in the net-normal dispersion regime. DSs with central wavelengths of 1572 and 1587 nm can be achieved simultaneously or respectively. The dual-wavelength DSs, traveling at different round-trip time, exhibit double-rectangular spectral profile. The intensities of two mode-locked spectra decrease or increase simultaneously after passing through a polarization beam splitter, indicating that the dual-wavelength DSs almost share the same polarization state. Experimental results demonstrated that dual-wavelength mode locking strongly depends on birefringence-induced filtering effect. PMID:23037222

Yun, Ling; Liu, Xueming; Mao, Dong

2012-09-10

19

Novel figure-eight fiber laser scheme including a power-symmetric nonlinear optical loop mirror with adjustable switching power  

NASA Astrophysics Data System (ADS)

We propose and study experimentally a novel passively mode-locked figure-eight fiber laser scheme based on a polarization-imbalanced Nonlinear Optical Loop Mirror (NOLM). In contrast to conventional power-imbalanced structures, the NOLM used in the proposed laser relies on a difference of nonlinear polarization rotation between the counter-propagating beams to provide switching. In this experiment, the polarization state at the NOLM input is set to linear. By controlling the polarization orientation at the NOLM input through a half-wave retarder plate, it is possible to adjust the NOLM switching power. This property of the NOLM is attractive in the frame of a figure-eight laser. Firstly, the switching power can be readily set to a value ensuring stable mode-locking operation, without having to cut into the loop and modify the NOLM length. On the other hand, we observed that stable pulsed operation is maintained over a certain range of the NOLM input polarization angle, whereas the pulse properties vary over that range. In particular, the spectral width varies from 16 to 52 nm over that range. This spectral variation is associated with a variation of the pulse temporal properties. This result can be explained by the fact that the input polarization angle allows controlling the critical power of the NOLM, which in turn affects the pulses characteristics. The proposed device thus offers a convenient way to adjust the pulses properties (in particular their spectral bandwidth and duration), simply by controlling the angle of a wave retarder, a property which is attractive for some applications.

Pottiez, O.; Grajales-Coutiño, R.; Ibarra-Escamilla, B.; Kuzin, E. A.; Hernandez-Garcia, J. C.; Gonzalez-Garcia, A.

2010-04-01

20

A passively-modelocked, Yb-doped, figure-eight, fiber laser utilizing anomalous-dispersion higher-order-mode fiber  

Microsoft Academic Search

Modelocking in an Yb-doped figure-eight fiber laser is demonstrated utilizing anomalous dispersion from an LP02 higher-order-mode fiber for dispersion management. Outside the laser cavity, the pulses were re-compressed to 95 fs using a second HOM module, the shortest demonstrated pulses to date from an Yb-doped figure-eight fiber laser. Operation of the laser with HOM fiber in the cavity is compared

J. W. Nicholson; S. Ramachandran; S. Ghalmi

2007-01-01

21

Calculation of motion induced eddy current forces in null flux coils  

SciTech Connect

Time dependent motion induced eddy current forces can be quite difficult to compute. The movement of null flux coils between magnets is approached using a coupled boundary element-circuit approach to compute the forces on the structure. The technique involves treating the magnets as a separate circuit whose current is dictated by the product of the magnet thickness and the working coercivity. The mutual inductance between the windows of the moving null flux coil and the stationary equivalent magnet coil hold the key for predicting lift, guidance, and drag forces on the coil. The rate of change of these inductances with respect to position determines the forces and currents. A steady state approximation to these forces is derived in addition to a numerical simulation when the steady state assumption is invalid. The results compare favorably to laboratory results from a 4 ft. diameter experimental test wheel.

Davey, K.; Morris, T. [American Maglev, Inc., Edgewater, FL (United States)] [American Maglev, Inc., Edgewater, FL (United States); Shaaf, J. [BDM Federal, Inc., Huntsville, AL (United States)] [BDM Federal, Inc., Huntsville, AL (United States); Rote, D. [Argonne National Lab., IL (United States)] [Argonne National Lab., IL (United States)

1995-11-01

22

Intelligent optical networking with photonic cross connections  

NASA Astrophysics Data System (ADS)

Optical amplification and dense wavelength division multiplexing (DWDM) have fundamentally changed optical transport networks. Now that these technologies are widely adopted, the bottleneck has moved from the outside line plant to nodal central offices, where electrical switching equipment has not kept pace. While OEO technology was (and still is) necessary for grooming and traffic aggregation, the transport network has dramatically changed, requiring a dramatic rethinking of how networks need to be designed and operated. While today's transport networks carry remarkable amounts of bandwidth, their optical layer is fundamentally static and provides for only simple point-to-point transport. Efficiently managing the growing number of wavelengths can only be achieved through a new breed of networking element. Photonic switching systems (PSS) can efficiently execute these functions because they are bit rate, wavelength, and protocol transparent. With their all-optical switch cores and interfaces, PSS can switch optical signals at various levels of granularity-wavelength, sub band, and composite DWDM fiber levels. Though cross-connect systems with electrical switch cores are available, they perform these functions at very high capital costs and operational inefficiencies. This paper examines enabling technologies for deployment of intelligent optical transport networks (OTN), and takes a practical perspective on survivability architecture migration and implementation issues.

Ceuppens, L.; Jerphagnon, Olivier L.; Lang, Jonathan; Banerjee, Ayan; Blumenthal, Daniel J.

2002-09-01

23

Experimental study to improve the focalization of a figure-eight coil of rTMS by using a highly conductive and highly permeable medium.  

PubMed

A method to improve the focalization of the repetitive transcranial magnetic stimulation figure-eight coil in a magnetic stimulation is presented in this paper. For the purpose of reducing the half width of the distribution curve, while improving the ratio of positive to negative electric field, a shield plate with a window and a magnetic conductor were adopted. The shield plate, which was made of highly conductive copper, focused the magnetic field into a smaller area. The magnetic inductor, which was made of highly permeable soft magnetic ferrite, strengthened the magnetic field. A group of experiments was conducted to validate the focalizing effect. Experimental results showed that the negative peak and the half width of the distribution curve reduced by using the shield plate and the magnetic conductor. Especially for to the Magstim 70 mm double coil, when the shield window was 30 × 60 mm, the ratio of positive to negative electric field could be increased 109%, while the half width of the distribution curve could be reduced about 55%. PMID:22531823

Zhang, Shunqi; Yin, Tao; Liu, Zhipeng; Li, Ying; Jin, Jingna; Ma, Ren

2013-05-01

24

Dual-keel electrodynamic Maglev system  

SciTech Connect

This paper introduces a new concept for an electrodynamic-suspension maglev system that has a dual-keel arrangement. Each keel consists of a row of superconducting magnets aboard the vehicle. The keels move in troughs in the guideway that are each lined with pairs of figure-eight-shaped null-flux coils. Each pair of null-flux coils is cross-connected to produce null-flux suspension and guidance force. The cross-connected figure-eight null-flux coils in each trough are also energized by a three-phase power supply to produce propulsive force. Preliminary analysis shows that the new system has many advantages over other EDS systems in terms of system performance and dynamic stability.

He, Jianliang; Rote, D.M.; Wang, Zian; Coffey, H.T.

1995-12-31

25

Scalable optical cross-connect switch using micromachined mirrors  

Microsoft Academic Search

This letter describes a free-space optical fiber cross-connect that uses a pair of micromirror arrays to redirect optical beams from an input-fiber array to an output array. This confocal switch architecture is well suited for simultaneous switching of multiple wavelength channels. We show that confocal switches with low insertion loss, low crosstalk, and large port counts can be implemented with

Paul M. Hagelin; Uma Krishnamoorthy; Jonathan P. Heritage; Olav Solgaard

2000-01-01

26

Multicasting optical cross connects employing splitter-and-delivery switch  

Microsoft Academic Search

A new splitter-and-delivery (SAD) switch having multicasting capability is proposed. It is best implemented in a single silicon board using planar silica waveguide technology. Less than -40-dB crosstalk is achievable by an auxiliary action of the optical gate. Three optical cross-connect architectures employing the SAD switch are proposed. They are strictly nonblocking and have multicasting capability. Furthermore, they have wavelength

Wei S. Hu; Qing J. Zeng

1998-01-01

27

Study of Japanese electrodynamic-suspension maglev systems  

NASA Astrophysics Data System (ADS)

This report presents the results of a study of the Japanese MLU magnetic levitation (maglev) system. The development of the MLU system is reviewed, and the dynamic circuit model then is introduced and applied to the figure-eight-shaped null-flux coil suspension system. Three different types of figure-eight-shaped null-flux suspension systems are discussed in detail: (1) the figure-eight-shaped null-flux coil suspension system without cross-connection; (2) the combined suspension and guidance system; and (3) the combined propulsion, levitation, and guidance system. The electrodynamic suspension maglev systems developed in Japan seem to be very promising and could result in a commercial application in the near future.

He, J. L.; Rote, D. M.; Coffey, H. T.

1994-04-01

28

Study of Japanese electrodynamic-suspension maglev systems  

SciTech Connect

This report presents the results of a study of the Japanese MLU magnetic-levitation (maglev) system. The development of the MLU system is reviewed, and the dynamic circuit model then is introduced and applied to the figure-eight-shaped null-flux coil suspension system. Three different types of figure-eight-shaped null-flux suspension systems are discussed in detail: (1) the figure-eight-shaped null-flux coil suspension system without cross-connection; (2) the combined suspension and guidance system; and (3) the combined propulsion, levitation, and guidance system. The electrodynamic-suspension maglev systems developed in Japan seem to be very promising and could result in a commercial application in the near future.

He, J.L.; Rote, D.M.; Coffey, H.T. [Argonne National Lab., IL (United States). Center for Transportation Research

1994-04-01

29

Cross-connection detection in Australian dual reticulation systems by monitoring inherent fluorescent organic matter  

Microsoft Academic Search

New housing developments are now commonly incorporating dual reticulation water systems for the redistribution of recycled water back to households for non-potable use. Within such distribution systems is the potential for cross-connections between recycled and drinking water pipelines, and a number of such events have been documented both in Australia and internationally. While many cross-connections are unlikely to present a

A. C. Hambly; R. K. Henderson; A. Baker; R. M. Stuetz; S. J. Khan

2012-01-01

30

Cascadability of all-optical cross connects based on wavelength conversion  

Microsoft Academic Search

Summary form only given. In a multiwavelength optical transport network, the optical cross connects (OXCs) route optical channels according to their respective wavelengths. The reconfiguration of the routing matrix aims at restoring the channels in case of failure and at fulfilling new traffic demands. Previous demonstrations have been made, based on space switching and tunable filtering. The flexibility of such

F. Tillerot; D. Hui Bon Hoa; R. Auffret; G. Claveau

1996-01-01

31

OTN-based, optical cross-connect systems to create reliable and transparent optical networks  

NASA Astrophysics Data System (ADS)

The Optical Transport Network (OTN) is the extremely important technology to create the next-generation core optical networks with the capacity of several Tbit/s, because it can contribute to the reliability and transparency. We discuss the OTN-based Optical Cross-Connect systems (OXCs), and verify the fast restoration using OTN functionality.

Tsushima, Hideaki; Fukashiro, Yasuyuki

2005-10-01

32

GORA: an algorithm for designing optical cross-connect nodes with improved dependability  

Microsoft Academic Search

This paper considers the problem of enhancing the dependability (availability and its influencing factors) of optical cross connect nodes. These nodes are expected to be a crucial part of future optical communication networks. The genetic optimum redundancy allocation (GORA) algorithm proposed here is based on a hybrid genetic algorithm and solves the dependability enhancement problem by optimizing the allocation of

Edward Mutafungwa

2002-01-01

33

Liquid crystal and grating-based multiple-wavelength cross-connect switch  

Microsoft Academic Search

We propose and demonstrate a liquid-crystal and grating based optical cross-connect add-drop switch that operates simultaneously on several wavelengths channels. We demonstrate an 8 channels switch with 4 nm channel spacing, a flat-top frequency response and 30 dB extinction ratio

J. S. Patel; Y. Silberberg

1995-01-01

34

Solid state optical space switches for network cross-connect and protection applications  

Microsoft Academic Search

Network protection and reconfiguration is becoming increasingly important in fiber optic communications systems. This is driven by the intense traffic and high cost of lost high-data-rate optical connections. Optical cross-connects at the nodes in transmission systems are developing rapidly in response. A key optical component required for these applications is an optical space switch. Since the required timescale of network

M. Donckers; W. H. G. Horsthuis

1997-01-01

35

Fiber Bragg grating-based large nonblocking multiwavelength cross-connects  

Microsoft Academic Search

Multiwavelength cross-connects (WXCs) will play a key role to provide mare reconfiguration flexibility and network survivability in wavelength division multiplexing (WDM) transport networks. In this paper, we utilize three different fiber Bragg grating (FBG)-based P-type, S-type, and N-type building blocks with optical circulators and related control devices for constructing large rearrangeably nonblocking N×N WXCs. The P-type building block is composed

Yung-Kuang Chen; Chien-Chung Lee

1998-01-01

36

Precision time-transfer in transport networks using digital cross-connect systems  

Microsoft Academic Search

A technique for precise synchronization of the time-of-day clocks in networks of digital cross-connect systems (DCSs) is described. This method is intended to enhance the performance of reconfigurable transport networks and is specifically devised to exploit the fine time resolution of the carrier signals to which a DCS has direct access. The resulting scheme is a master-slave, multisite, implicitly delay

W. D. Grover; T. E. Moore

1990-01-01

37

Three-dimensional MEMS photonic cross-connect switch design and performance  

Microsoft Academic Search

Photonic cross-connects (PXC) play a key role in all-optical transparent networks. In this paper, the optical design and modeling of a three-dimensional microelectromechanical system (3-D MEMS) based optical switch are discussed. Basic design rules and considerations are reviewed and used to determine the optimum configuration for free-space optical switches with more than 300 ports. The optical performance of a 256

Xuezhe Zheng; Volkan Kaman; Shifu Yuan; Yuanjian Xu; Olivier Jerphagnon; Adrian Keating; Robert C. Anderson; Henrik N. Poulsen; Bin Liu; James R. Sechrist; Chandrasekhar Pusarla; Roger Helkey; Daniel J. Blumenthal; John E. Bowers

2003-01-01

38

A two-dimensional optical cross-connect with integrated waveguides and surface micromachined crossbar switches  

Microsoft Academic Search

The design, fabrication and test results of an all-optical cross-connect, which uses electrostatically actuated micromechanical digital mirrors to steer optical signals in a network of planar waveguides, are presented. The substrate consists of a network of spliced planar waveguides on silica substrates. The switches, located at the waveguide intersections, are formed with an electroplated T-structure consisting of a horizontal perforated

N. Iyer; C. H. Mastrangelo; S. Akkaraju; C. Brophy; T. G. McDonald; R. Dureiko; E. T. Carlen

2004-01-01

39

An architecture for a wavelength-interchanging cross-connect utilizing parametric wavelength converters  

Microsoft Academic Search

This paper proposes an architecture for a wavelength-interchanging cross-connect (WIXC) that can be used as a switching node of strictly transparent and scalable networks with all-optical routing and all-optical wavelength conversion capabilities. This architecture utilizes all-optical parametric wavelength converters based on difference-frequency-generation (DFG) or four-wave mixing (FWM), although this work focuses only on the implementation using difference-frequency-generation wavelength converters. The

N. Antoniades; S. J. B. Yoo; Krishna Bala; Georgios Ellinas; Thomas E. Stern; Life Fellow

1999-01-01

40

Two novel multi-granularity optical cross-connect architectures for hierarchical optical networks  

Microsoft Academic Search

Two novel multi-granularity optical cross-connect (MG-OXC) architectures for dense wavelength division multiplexing (DWDM) networks are proposed to realize transparent waveband switching, and hence to reduce the switching and transmission costs. The performances of the two architectures are studied and compared in detail. The functionality of the proposed interconnecting architecture is investigated for a 10-Gb\\/s WDM system.

Yongmin Qi; Xiangqing Tian; Yaohui Jin; Weisheng Hu

2006-01-01

41

Optical Cross-Connect Switch Architectures for Hierarchical Optical Path Networks  

NASA Astrophysics Data System (ADS)

This paper proposes new switch architectures for hierarchical optical path cross-connect (HOXC) systems. The architectures allow incremental expansion of system scale in terms of the number of input/output fiber ports, wavebands, and optical paths per waveband. These features assure the cost-effective introduction of HOXCs even at the outset when traffic volume is not so large. Furthermore the effectiveness of the proposed switch architectures is demonstrated in a comparison with single-layer OXCs (conventional OXCs). The results provide useful criteria for the introduction of HOXCs in terms of hardware scale.

Kakehashi, Shoji; Hasegawa, Hiroshi; Sato, Ken-Ichi

42

Dynamic multi-path WDM routing in a monolithically integrated 8 × 8 cross-connect.  

PubMed

We demonstrate for the first time WDM multi-path routing through a monolithically integrated InP/InGaAsP 8 × 8 space and wavelength selective cross-connect. Data channels are dynamically routed from four input ports to the same output port with excellent OSNR from 27.0 to 31.1 dB. Representative data paths are evaluated in terms of optical power penalty. Data routing experiments are performed using round-robin scheduling with nanosecond time-scale switching times. PMID:24515003

Stabile, Ripalta; Rohit, Abhinav; Williams, Kevin A

2014-01-13

43

Combining circuit and packet switching using a large port-count optical cross-connect for data center networks  

NASA Astrophysics Data System (ADS)

The exponential increase in the data center network traffic has posed new challenges for achieving high throughput, low latency and energy consumption. To address these challenges, this paper presents a novel scheme that combines optical circuit and packet switching technologies together in a single optical cross-connect for data center networks. By utilizing fast tunable linecards and parallel array waveguide grating routers, the optical cross-connect can offer low latency, large scalability and high throughput in datacenter networks. A scheduling technique is designed to simultaneously accommodate circuit switching and packet switching in the optical cross-connect. The physical performance of this optical cross-connect in circuit and packet switching modes is investigated by experiments. In addition, the network performance of the optical cross-connect is evaluated through simulations under a mixed circuit/packet-switched traffic pattern. Results show that the network performance of the optical cross-connect does not degrade significantly with an increase in the number of racks, but it is affected by the circuit-switched traffic proportion.

Huang, Qirui; Yeo, Yong-Kee; Zhou, Luying

2012-10-01

44

Fiber-handling robot and optical connection mechanisms for automatic cross-connection of multiple optical connectors  

NASA Astrophysics Data System (ADS)

Conventionally, in intelligent buildings in a metropolitan area network and in small-scale facilities in the optical access network, optical connectors are joined manually using an optical connection board and a patch panel. In this manual connection approach, mistakes occur due to discrepancies between the actual physical settings of the connections and their management because these processes are independent. Moreover, manual cross-connection is time-consuming and expensive because maintenance personnel must be dispatched to remote places to correct mistakes. We have developed a fiber-handling robot and optical connection mechanisms for automatic cross-connection of multiple optical connectors, which are the key elements of automatic optical fiber cross-connect equipment. We evaluate the performance of the equipment, such as its optical characteristics and environmental specifications. We also devise new optical connection mechanisms that enable the automated optical fiber cross-connect module to handle and connect angled physical contact (APC) optical connector plugs. We evaluate the performance of the equipment, such as its optical characteristics. The evaluation results confirm that the automated optical fiber cross-connect equipment can connect APC connectors with low loss and high return loss, indicating that the automated optical fiber cross-connect equipment is suitable for practical use in intelligent buildings and optical access networks.

Mizukami, Masato; Makihara, Mitsuhiro

2013-07-01

45

A service restoration time study for distributed control SONET digital cross-connect system self-healing networks  

Microsoft Academic Search

The viability of distributed control restoration using digital cross-connect systems (DCSs) depends on its capability for restoring services within specified time requirements. A Bellcore study of the impact of the DCS architecture on distributed restoration is reported. It is concluded that currently proposed distributed control DCS self-healing schemes may not meet the two-second restoration objective, regardless of the distributed algorithm,

T.-H. Wu; H. Kobrinski; D. Ghosal; T. V. Lakshman

1993-01-01

46

Performance simulation for a novel joint multicasting optical cross-connect based on both space and frequency splitters  

Microsoft Academic Search

The emerging broadband real-time streams applications require the supporting networks to provide multicasting communication at optical layer. The multicasting capable optical cross-connect (MC-OXCs) is the necessary device to implement multicasting at optical layer. The functional building blocks for MC-OXC are light splitters, which can be space splitters or multiwavelength converters (frequency splitters). The space splitter has no wavelength conversion ability,

Yunfeng Peng; Weiqiang Sun; Weisheng Hu; Yaohui Jin; Yongmin Qi

2005-01-01

47

Evaluation and experiment of a configuration algorithm for three-stage multi-granularity optical cross-connects  

Microsoft Academic Search

From element automatic control view, we propose a configuration algorithm for three-level cross-connects in data plane to handle with bypass, grooming and local add\\/drop traffic of fiber-level, band-level and wavelength-level by a abstract bipartite graph of MG-OXC and bandwidth utilization spectra graph. The configuration algorithm is evaluated by computer simulation as well as validated by experiment on our flexible Multi-functional

Yongmin Qi; Yaohui Jin; Weisheng Hu; Yue Wang; Chunlei Zhang; Peigang Hu; Yang Lu; Yi Zhang; Siye Zuo; Yunfeng Peng; Hao He

2005-01-01

48

The impact of waveband size on the number of ports of cross-connect in waveband switching networks  

NASA Astrophysics Data System (ADS)

This paper investigated the influence of the waveband parameters on the number of ports of optical cross-connect (OXC) in waveband switching networks. The concept of waveband switching has been studied to decrease size of OXC when the number of wavelength increases, and the waveband parameters influence the size of OXC. We defined two waveband parameters; One is the number of path in a waveband and another is minimum number of the paths to group. The later waveband parameter means to allow several unused wavelength in a waveband. We evaluated the number input ports of OXC and the number of required wavelength with changing the parameters. The routing algorithm takes account of the delay of routes and of equalization of the number of wavelength in a link. Waveband path groups several wavelength paths with the same part of route in this simulation. Numerical experiments show that the wide bandwidth of a waveband saves the number of ports of OXC when the network has large traffic volume. On the other hand, if unused wavelength is allowed in a waveband, the number of port of OXC can be decreased, but the maximum number of wavelength in network is much required.

Karube, Ryo; Takano, Katsumi; Ito, Tomohiro; Nakagawa, Kiyoshi

2010-12-01

49

EVALUATION OF THE ABILITY OF CHLORINE TO INACTIVATE SELECTED ORGANISMS FROM THE BIOFILM OF A DRINKING WATER DISTRIBUTION SYSTEM SIMULATOR FOLLOWING A LONG-TERM WASTEWATER CROSS-CONNECTION  

EPA Science Inventory

The drinking water distribution system simulator (DSS) from the U.S. EPA was operated with a direct cross-connection of 0.3% wastewater to system volume per day for 70 d. During the cross-connection, tap water, wastewater, and system discharge water were monitored to ensure that ...

50

SDH network in Japan and SDH 52\\/156 Mbps (VC3\\/4) digital cross-connect systems with hit-less switching function  

Microsoft Academic Search

Since 1989, NTT has been using the synchronous digital hierarchy (SDH) transmission system to create simplified, easy-to-operate transmission networks in Japan. This paper describes the SDH networks at NTT and the newly developed SDH 52M\\/156M digital cross-connect system (Module AX), which enables real-time VC-3\\/VC-4 path level network operation and hit-less switching, thus providing support for relocation of existing telecommunication cables

Kazuhiro Nishihata; Shun-ichi Umino; Terufumi Shinomiya

1994-01-01

51

CHEMICAL EXPOSURES AND ANIMAL ACTIVITY: UTILITY OF THE FIGURE-EIGHT MAZE  

EPA Science Inventory

The need for rapid and inexpensive tests in toxicology has prompted several advisory panels to recommend motor activity as a screen for neurotoxicity. Since motor activity reflects the general status of the organism, disruption produced by a variety of neurotoxic and non-neurotox...

52

Computation of Magnetic Suspension of Maglev Systems Using Dynamic Circuit Theory.  

National Technical Information Service (NTIS)

Dynamic circuit theory is applied to several magnetic suspensions associated with maglev systems. These suspension systems are the loop-shaped coil guideway, the figure-eight-shaped null-flux coil guideway, and the continuous sheet guideway. Mathematical ...

J. L. He D. M. Rote H. T. Coffey

1992-01-01

53

Effect of Correlations of Component Failures and Cross-Connections of EDGs on Seismically Induced Core Damages of a Multi-Unit Site  

NASA Astrophysics Data System (ADS)

Aiming at proposing effective applications of seismic probabilistic safety assessment (PSA) for design and risk management of nuclear facilities, we conducted a preliminary seismic PSA study for a multi-unit site to examine core damage frequency (CDF) and core damage sequences with consideration of the effect of correlations of component failures. In addition, we also examined the effectiveness of an accident management measure, namely, cross-connections of emergency diesel generators (EDGs) between adjacent units in this study. Twin BWR-5 units of the same design were hypothesized to be located at the same site in this study and the CDF as well as the accident sequences of this two-unit site were analyzed by using SECOM2, a system reliability analysis code for seismic PSA. The results showed that the calculated CDF was dependent on the assumptions on the correlations of component failures. When the rules for assigning correlation coefficients of component responses defined in the NUREG-1150 program were adopted, the CDF of a single unit, the CDF of this two-unit site (the frequency of core damages of at least one unit at this site) and the frequency of simultaneous core damages of both units increased by factors of about 1.3, 1.2 and 2.3, respectively. In addition, it might be possible that the simultaneous core damages of both units are caused by different accident sequence pairs as well as the same sequence pairs. When cross-connections of EDGs between two units were available, the CDF of a single unit, the CDF of this two-unit site as well as the frequency of simultaneous core damages of both units decreased. In addition, the CDF of this two-unit site was smaller than the CDF of a single unit site. These results show that cross-connections of EDGs might be beneficial for a multi-unit site if the rules for assigning correlation coefficients defined in NUREG-1150 program are reasonable.

Muramatsu, Ken; Liu, Qiao; Uchiyama, Tomoaki

54

Acetabular retroversion as a rare cause of chronic hip pain: recognition of the “figure-eight” sign  

Microsoft Academic Search

While well-recognized in the orthopedic literature as a cause of chronic hip pain, acetabular retroversion has not been specifically\\u000a described in the radiologic literature. Acetabular retroversion represents a particular form of hip dysplasia characterized\\u000a by abnormal posterolateral orientation of the acetabulum. This pathophysiology predisposes the individual to subsequent anterior\\u000a impingement of the femoral neck upon the anterior acetabular margin and

Kevin P. Banks; David E. Grayson

2007-01-01

55

Index and Stability of Symmetric Periodic Orbits in Hamiltonian Systems with Application to Figure-Eight Orbit  

Microsoft Academic Search

In this paper, using the Maslov index theory in symplectic geometry, we build up some stability criteria for symmetric periodic\\u000a orbits in a Hamiltonian system, which is motivated by the recent discoveries in the n-body problem. The key ingredient is a generalized Bott-type iteration formula for periodic solution in the presence of finite\\u000a group action on the orbit. For second

Xijun Hu; Shanzhong Sun

2009-01-01

56

Time-Frequency Analysis of a Noisy Ultrasound Doppler Signal With a 2nd Figure Eight Kernel.  

National Technical Information Service (NTIS)

Nonstationary ultrasound Doppler signals, those are changing with time and frequency simultaneously, are widely observed in biological and speech signals. A Cohen's class time-frequency (TF) analysis can analyze nonstationary signals with high resolution ...

Y. Noguchi E. Kashiwagi K. Watanabe F. Matsumoto S. Sugimoto

2001-01-01

57

Integrated null-flux suspension and multiphase propulsion system for magnetically-levitated vehicles  

DOEpatents

A propulsion and stabilization system are described comprising a series of coils mounted vertically on the walls of the guideway to provide suspension, lateral guidance, and propulsion of a magnetically levitated vehicle. This system further allows for altering the magnetic field effects by changing the relative position of the loops comprising the coils either longitudinally and/or vertically with resulting changes in the propulsion, the vertical stability, and the suspension. 8 figures.

Rote, D.M.; He, J.; Johnson, L.R.

1994-01-04

58

Integrated null-flux suspension and multiphase propulsion system for magnetically-levitated vehicles  

DOEpatents

This report discusses a propulsion and stabilization system comprising a series of figure 8 coils mounted vertically on the walls of the guideway to provide suspension, lateral guidance and propulsion of a magnetically levitated vehicle. This system further allows for altering the magnetic field effects by changing the relative position of the loops comprising the figure 8 coils either longitudinally and/or vertically with resulting changes in the propulsion, the vertical stability, and the suspension.

Rote, D.M.; He, Jianliang; Johnson, L.R.

1992-01-01

59

Applications of the dynamic circuit theory to Maglev suspension systems  

Microsoft Academic Search

The applications of dynamic circuit theory to electrodynamic suspension (EDS) systems are discussed. Emphasis is placed on the loop-shaped coil and the figure-eight-shaped null-flux coil suspension systems. Mathematical models, including very general force expressions that can be used for the development of computer codes, are provided for each of these suspension systems. The general applications and advantages of the dynamic

Jian Liang He; Donald M. Rote; Howard T. Coffey

1993-01-01

60

Electrostatically actuated micro-fluidic optical cross-connect switch  

Microsoft Academic Search

An electrostatically actuated micro-fluidic OXC switch based on PLC and MEMS technologies has been developed. The motion of the fluid is controlled by the displacement of a mechanical diaphragm driven by an electrostatic actuator in order to ensure low power consumption and enhanced reliability. Specific technological developments have been made for the fabrication of 2 × 2 and 8 ×

E. Ollier; C. Divoux; J. Margail; T. Enot; L. Ortiz; Y. Gobil; M. Salhi; P. Berruyer; A. Gliere; A. Bontemps; M. Laporte; M. Bruel

2003-01-01

61

Microsecond regime optical cross connect: 32 port to 32 port scalable device  

NASA Astrophysics Data System (ADS)

Presented here is a 32 × 32 optical switch for telecommunications applications capable of reconfiguring at speeds of up to 12 microseconds. The free space switching mechanism in this interconnect is a digital micromirror device (DMD) consisting of a 2D array of 10.8?m mirrors optimized for implementation at 1.55?m. Hinged along one axis, each micromirror is capable of accessing one of two positions in binary fashion. In general reflection based applications this corresponds to the ability to manifest only two display states with each mirror, but by employing this binary state system to display a set of binary amplitude holograms, we are able to access hundreds of distinct locations in space. We previously demonstrated a 7 × 7 switch employing this technology, providing a proof of concept device validating our initial design principles but exhibiting high insertion and wavelength dependent losses. The current system employs 1920 × 1080 DMD, allowing us to increase the number of accessible ports to 32 × 32. Adjustments in imaging, coupling component design and wavelength control were also made in order to improve the overall loss of the switch. This optical switch performs in a bit-rate and protocol independent manner, enabling its use across various network fabrics and data rates. Additionally, by employing a diffractive switching mechanism, we are able to implement a variety of ancillary features such as dynamic beam pick-off for monitoring purposes, beam division for multicasting applications and in situ attenuation control.

Lynn, Brittany; Miles, Alexander; Blanche, Pierre-Alexandre; Wissinger, John; Carothers, Daniel; Norwood, Robert A.; Peyghambarian, N.

2014-03-01

62

Free-Space Optical Cross-Connect Switch by Use of Electroholography  

Microsoft Academic Search

An electrically controlled holographic switch is proposed as a building block for a free-space optical interconnection network. The switch is based on the voltage-controlled photorefractive effect in KLTN crystals at the paraelectric phase. It is built of electrically controlled Bragg gratings stored in the volume of the crystal. A compact switch that connects four high-speed fiber-optic communication channels with high

Benny Pesach; Guy Bartal; Eli Refaeli; Aharon J. Agranat; Joel Krupnik; Dan Sadot

2000-01-01

63

Free-space optical cross-connect switch by use of electroholography.  

PubMed

An electrically controlled holographic switch is proposed as a building block for a free-space optical interconnection network. The switch is based on the voltage-controlled photorefractive effect in KLTN crystals at the paraelectric phase. It is built of electrically controlled Bragg gratings stored in the volume of the crystal. A compact switch that connects four high-speed fiber-optic communication channels with high efficiency is demonstrated experimentally. The switch performance is investigated and optimized. This switch is extremely attractive for cascaded switching arrays such as those found in multistage interconnect networks. PMID:18337949

Pesach, B; Bartal, G; Refaeli, E; Agranat, A J; Krupnik, J; Sadot, D

2000-02-10

64

Optimization design of three-stage multigranularity optical cross-connects  

Microsoft Academic Search

We study the design issues of a node in multi-granularity all-optic network based on a proposed dynamic multigranularity including coarse granularity (i.e., fiber and band) and fine granularity (i.e., wavelength) traffic model. An optimization design plan is proposed by analyzing the associated parameters of MG-OXC architecture in detail and optimizing the configuration of them. The proposed optimization design rules can

Yongmin Qi; Yaohui Jin; Weisheng Hu

2005-01-01

65

Computation of magnetic suspension of maglev systems using dynamic circuit theory  

NASA Technical Reports Server (NTRS)

Dynamic circuit theory is applied to several magnetic suspensions associated with maglev systems. These suspension systems are the loop-shaped coil guideway, the figure-eight-shaped null-flux coil guideway, and the continuous sheet guideway. Mathematical models, which can be used for the development of computer codes, are provided for each of these suspension systems. The differences and similarities of the models in using dynamic circuit theory are discussed in the paper. The paper emphasizes the transient and dynamic analysis and computer simulation of maglev systems. In general, the method discussed here can be applied to many electrodynamic suspension system design concepts. It is also suited for the computation of the performance of maglev propulsion systems. Numerical examples are presented in the paper.

He, J. L.; Rote, D. M.; Coffey, H. T.

1992-01-01

66

Applications of the dynamic circuit theory to maglev suspension systems  

SciTech Connect

This paper discusses the applications of dynamic circuit theory to electrodynamic suspension EDS systems. In particular, the paper focuses on the loop-shaped coil and the figure-eight-shaped null-flux coil suspension systems. Mathematical models, including very general force expressions that can be used for the development of computer codes, are provided for each of these suspension systems. General applications and advantages of the dynamic circuit model are summarized. The paper emphasizes the transient and dynamic analysis and computer simulation of maglev systems. In general, the method discussed here can be applied to many EDS maglev design concepts. It is also suited for the computation of the performance of maglev propulsion systems. Numerical examples are presented in the paper to demonstrate the capability of the model.

He, Jian Liang; Rote, D.M.; Coffey, H.T. [Argonne National Lab., IL (United States). Center for Transportation Research

1993-11-01

67

Computation of magnetic suspension of maglev systems using dynamic circuit theory  

SciTech Connect

Dynamic circuit theory is applied to several magnetic suspensions associated with maglev systems. These suspension systems are the loop-shaped coil guideway, the figure-eight-shaped null-flux coil guideway, and the continuous sheet guideway. Mathematical models, which can be used for the development of computer codes, are provided for each of these suspension systems. The differences and similarities of the models in using dynamic circuit theory are discussed in the paper. The paper emphasizes the transient and dynamic analysis and computer simulation of maglev systems. In general, the method discussed here can be applied to many electrodynamic suspension system design concepts. It is also suited for the computation of the performance of maglev propulsion systems. Numerical examples are presented in the paper. 15 refs., 7 figs., 1 tab.

He, J.L.; Rote, D.M.; Coffey, H.T.

1991-01-01

68

Effect of an out-of-plane cross connection on the electronic transport of zigzag graphene nanoribbon  

NASA Astrophysics Data System (ADS)

Electronic transport properties of out-of-plane graphene nanoribbon intersections have been investigated by using computational method. The inter-distance between two graphene nanoribbons is found to affect the transport properties strongly and its affection can be neglected for larger ones, even under an external bias. Wider graphene nanoribbons will bring stronger interaction into the system, and result in more transmission dips. Moreover, the stacking configuration between two graphene nanoribbons is found to be crucial for the electronic transport under an external bias, as it can affect the electronic transport strongly near the charge neutral point.

Dai, Chang-Jie; Yan, Xiao-Hong; Guo, Yan-Dong; Xiao, Yang

2012-05-01

69

Performance enhancements of the CMCC"s national mesh network using the intelligent optical cross-connect switches  

NASA Astrophysics Data System (ADS)

In the last five years, the traffic growth rate in China has been extremely fast. By 2005, the number of wired telephone customers is estimated to reach 220 to 260 million, while the number of expected cellular customers will reach 260 to 290 million. To meet these challenges, we will continue evolving with more wavelengths and higher speed. By evolving point-to-point WDM systems to OTN/ASON systems, we can eliminate the throughput bottleneck of network nodes caused by electronics, provide optical-layer bandwidth- management capability, provide scalability (which allows continuous traffic growth and network expansion), and provide reconfigurability (which allows semi-dynamic and dynamic optical networking). We can also simplify and speed up provisioning of high-speed circuits and services and offer fast network protection and restoration on the order of tens or hundreds of milliseconds to guarantee excellent network and service survivability. The CMCC (China Mobile Communication Company) will build its OTN network towards the ASON. The CMCC"s long-haul national network utilizing OXC has clearly becomes an intelligent network. It offers end-to-end point-and-click provisioning, shared mesh restoration with a few tens to a couple of hundred msec restoration times, re-provisioning of connections in the event of double failures and network capacity that is not optimally used. In this paper, first we present the CMCC network situation, The network planning tool will be introduced, Then we compare ring with mesh solution in terms of the cost, network performance, protection and restoration, network re-optimization. At last we derive a desired conclusion.

Gong, Qian; Xu, Rong; Lin, JinTong L.

2004-04-01

70

THE EFFECT OF LONG TERM WASTEWATER CROSS-CONNECTION'S EFFECT ON THE BIOFILM OF A SIMULATED WATER DISTRIBUTION SYSTEM  

EPA Science Inventory

Under the current regulations (CFR 503), Class B biosolids may be land applied with certain site restrictions. One method for achieving Class B status is to raise the pH of the sludge to >12 for a minimum of 2 hours with an alkaline material (normally lime). Alternately, a Clas...

71

77 FR 29618 - The Release of the Draft Environmental Impact Statement and the Announcement of a Public Hearing...  

Federal Register 2010, 2011, 2012, 2013

...a Public Hearing for the Figure Eight Island Inlet and Shoreline Management Project, on Figure Eight Island, New Hanover County, NC AGENCY: Department...and northern sections of Figure Eight Island. The terminal groin structure will...

2012-05-18

72

Transformation of contrails into cirrus during SUCCESS  

Microsoft Academic Search

Three contrail systems were analyzed with geostationary satellite data to document the conversion of the contrails to cirrus clouds. Two unique contrails, a pair of figure eights and a NASA DC-8 oval, were tracked for more than 7 hours. A cluster of contrails from commercial aircraft lasted over 17 hours. The figure eights produced a cirrus cloud having a maximum

Patrick Minnis; David F. Young; Donald P. Garber; Louis Nguyen; William L. Smith; Rabindra Palikonda

1998-01-01

73

Design of NSLS-II High Order Multipole Correctors  

SciTech Connect

Feasibility studies for two families of corrector magnets for NSLS-II are presented. The first family of magnets are generalizations of figure eight quadrupoles using rotationally symmetric breaks in the return yoke to fit in available space. Properties specific to figure eight magnet are identified. The second type of magnet is a combined sextupole/dipole trim.

Rehak,M.; Danby, G.; Bengtsson, Jo; Jackson, J.; Skaritka, J.; Spataro, C.

2009-05-04

74

47 CFR 69.121 - Connection charges for expanded interconnection.  

Code of Federal Regulations, 2010 CFR

...subelement shall be established for charges associated with the cross-connect...or switched access services. Charges for the cross-connect subelement...for purposes of jurisdictional separations. (2) Charges for subelements...

2009-10-01

75

47 CFR 69.121 - Connection charges for expanded interconnection.  

Code of Federal Regulations, 2010 CFR

...subelement shall be established for charges associated with the cross-connect...or switched access services. Charges for the cross-connect subelement...for purposes of jurisdictional separations. (2) Charges for subelements...

2010-10-01

76

47 CFR 69.121 - Connection charges for expanded interconnection.  

Code of Federal Regulations, 2013 CFR

...subelement shall be established for charges associated with the cross-connect...or switched access services. Charges for the cross-connect subelement...for purposes of jurisdictional separations. (2) Charges for subelements...

2013-10-01

77

Cyclo[6]pyridine[6]pyrrole: A Dynamic, Twisted Macrocycle with No Meso Bridges.  

PubMed

A large porphyrin analogue, cyclo[6]pyridine[6]pyrrole, containing no meso bridging atoms, has been synthesized through Suzuki coupling. In its neutral form, this macrocycle exists as a mixture of two figure-eight conformers that undergo fast exchange in less polar solvents. Upon protonation, the dynamic twist can be transformed into species that adopt a ruffled planar structure or a figure-eight shape depending on the extent of protonation and counteranions. Conversion to a bisboron difluoride complex via deprotonation with NaH and treatment with BF3 acts to lock the macrocycle into a figure-eight conformation. The various forms of cyclo[6]pyridine[6]pyrrole are characterized by distinct NMR, X-ray crystallographic, and spectroscopic features. PMID:24813693

Zhang, Zhan; Cha, Won-Young; Williams, Neil J; Rush, Elise L; Ishida, Masatoshi; Lynch, Vincent M; Kim, Dongho; Sessler, Jonathan L

2014-05-28

78

Independent gain and bandwidth control of a traveling wave maser  

NASA Technical Reports Server (NTRS)

An X-band traveling wave maser of the folded-comb type is presented, with two figure-eight coils for gain and bandwidth control. One figure-eight coil covers the full lengths of the comb structure for bandwidth adjustment of an external magnetic field. The other coil covers a central half of the comb structure for independent gain adjustment of the external magnetic field. The half of each figure-eight coil at the turn around end of the comb structure is oriented to aid the external magnetic field, and the half of each coil at the input-output end of the comb structure is oriented to buck the external magnetic field. The maser is pumped in the push-push mode with two different frequencies.

Trowbridge, D. L. (inventor)

1977-01-01

79

40 CFR 205.165 - Definitions.  

Code of Federal Regulations, 2013 CFR

...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle Exhaust Systems...other exhaust system components which provide noise attenuation. Tubes with cross connections...

2013-07-01

80

AUDITORY DEFICITS AND MOTOR DYSFUNCTION FOLLOWING IMINODIPROPIONITRILE ADMINISTRATION IN THE RAT  

EPA Science Inventory

The behavioral effects of 3,3'-iminodipropionitrile (IDPN) were studied using reflex modification of the acoustic startle response and figure-eight maze activity. umber of experiments were conducted with separate groups of adult male Long Evans hooded rats exposed to saline, or 5...

81

Analemma Project: Sub-Solar Cup Activity  

NSDL National Science Digital Library

This site from Paper Plate Education provides an activity using only a globe and plastic cup to determine the position on the earth where the sun appears directly overhead. Plotting this point on several days throughout a year yields an analemma, a figure-eight shape on the globe. The site provides background information, a gallery of pictures, and links to more activities.

Bueter, Chuck

2006-07-22

82

Repetition rate multiplication in eight microstructured optical fiber laser  

Microsoft Academic Search

For decades, passively mode locked fiber laser have been a very rich research field and today short pulsed laser with high energy and high repetition rate find many applications in areas of many fundamental research. In this paper, we propose a passively mode locked figure-eight fiber laser (8FL) totally made up of microstructured optical fiber (MOF) and incorporating two single

Tarek Ennejah; Faouzi Bahloul; Rabah Attia

2009-01-01

83

NEUROBEHAVIORAL EFFECTS OF TRIADIMEFON, A TRIAZOLE FUNGICIDE, IN MALE AND FEMALE RATS  

EPA Science Inventory

Triadimefon is a widely used systemic fungicide, yet there is little published information on its effects in mammals. This study describes the effects of triadimefon in male and female rats using a functional observational battery (FOB), motor activity (measured in a figure-eight...

84

Sampling Effects on Trajectory Learning and Production.  

National Technical Information Service (NTIS)

The time-delay neural network (TDNN) and the adaptive time-delay neural network (ATNN) are effective tools for signal production and trajectory generation. Previous studies have shown production of circular and figure-eight trajectories to be robust after...

D. Lin J. E. Dayhoff

1994-01-01

85

Recent advances in transcranial magnetic stimulation: From first principles to medical applications  

Microsoft Academic Search

Transcranial magnetic stimulation (TMS) is a technique to stimulate the human brain transcranially by a coil positioned on the surface of the head. Time-varying magnetic fields generated by the coil induce electric fields which stimulate neurons in the brain. By using a figure-eight coil, localized area of the brain can be stimulated, which enables us to study dynamic neuronal connectivity

Shoogo Ueno

2011-01-01

86

Theoretical and experimental determination of capstan drive slip error  

Microsoft Academic Search

Cable capstan drives are rotary transmission elements widely used in robot applications because of their low inertia, low backlash, high stiffness and simplicity. The cable in capstan drives is typically wrapped around the input and output drums in a figure-eight pattern and is the principle component for power transmission. In this paper an analytical method is developed for predicting the

Ozgur Baser; E. Ilhan Konukseven

2010-01-01

87

Theoretical and experimental determination of capstan drive stiffness  

Microsoft Academic Search

Cable or metal band capstan drives are used as rotary transmission elements for their very low (nominally zero) backlash and high stiffness properties. Cable drives, in particular, are found in many types of equipment, and to obtain high stiffness, the cable is typically wrapped around the input and output drum in a figure-eight pattern. This paper develops analytical methods for

Jaime Werkmeister; Alexander Slocum

2007-01-01

88

Theoretical and Experimental Determination of the Stiffness Properties of a Capstan Drive  

Microsoft Academic Search

Wire capstan drives are used as rotary transmission elements for their very low (nominally zero) backlash and high stiffness properties. To obtain high stiffness, the cable is typically wrapped around the input and output drum in a figure-eight pattern multiple times. This stiffness can be determined by analyzing the amount of deformation between the cable and the drums and the

Jaime Werkmeister; Alexander Slocum

89

Comparison of standing wave and traveling wave resonators for an FIR laser  

Microsoft Academic Search

The output powers of various linear and folded configurations of standing wave and traveling wave ring resonators for a FIR laser are compared. Output powers were measured for a linear standing wave laser and a ring laser of the same gain length and mode size, and for a folded standing wave laser and a figure-eight ring laser of the same

Y. C. Nii

1980-01-01

90

Unified System of Reflecting Spatial Relations of Outside World in Honeybee Apis Mellifera L.  

National Technical Information Service (NTIS)

There are two basic types of signal dance in the bee: figure eight and circular. At this time the character of motion of a dancing bee is judged on the basis of the trajectory of one point of its body. A cinematographic analysis was made of the character ...

S. V. Pankova

1970-01-01

91

A dynamic neural network identification of electromyography and arm trajectory relationship during complex movements  

Microsoft Academic Search

The authors propose a new approach based on dynamic recurrent neural networks (DRNN) to identify, in human, the relationship between the muscle electromyographic (EMG) activity and the arm kinematics during the drawing of the figure eight using an extended arm. After learning, the DRNN simulations showed the efficiency of the model. The authors demonstrated its generalization ability to draw unlearned

G. Cheron; J.-P. Draye; M. Bourgeios; G. Libert

1996-01-01

92

On the algebraic components of the SL(2, C ) character varieties of knot exteriors  

Microsoft Academic Search

We show that if a knot exterior satisfies certain conditions, then it has finite cyclic coverings with arbitrarily large numbers of nontrivial algebraic components in their SL(2,C) character varieties (Theorem A). As an example, these conditions hold for hyperbolic punctured torus bundles over the circle (Theorem B). We investigate in more detail the finite cyclic covers of the figure-eight knot

S. Boyer; E. Luft; X. Zhang

2002-01-01

93

Design of high density pin board matrix switches for automated main distributing frame systems  

Microsoft Academic Search

High-density pin board matrix switches composed of matrix boards and connecting pins are designed to provide the cross connection function of an automated main distributing frame (AMDF) system. The cross connection is performed by inserting a connecting pin into a through hole on the matrix board. A small economic AMDF system is made possible by using a laminated matrix board

Shigeru Umemura; Tsuneo Kanai; Shuichiro Inagaki; Yasuo Kumakura

1992-01-01

94

The design and characteristic features of a new time-of-flight mass spectrometer with a spiral ion trajectory  

Microsoft Academic Search

A new time-of-flight (TOF) mass spectrometer with a corkscrew ion trajectory was designed and constructed. The spiral trajectory\\u000a was realized by using four toroidal electrostatic sectors. Each had fifteen-stories made of sixteen Matsuda plates piled up\\u000a inside a cylindrical electrostatic sector. The ions passed the four toroidal electrostatic sectors sequentially and revolved\\u000a along a figure-eight-shaped orbit on a certain projection

Takaya Satoh; Hisayuki Tsuno; Mitsuyasu Iwanaga; Yoshihiro Kammei

2005-01-01

95

IS 911 -mediated Transpositional Recombination in Vitro  

Microsoft Academic Search

A cell-free system is described that accomplishes an unusual type of transposition\\/recombination involving the bacterial insertion sequence IS911. Using a plasmid substrate carrying a derivative of IS911, we show that bacterial cell extracts enriched for the IS911transposase, OrfAB, carry out a single-strand cleavage and transfer reaction. This results in the formation of a figure-eight molecule in which a single strand

Patrice Polard; Bao Ton-Hoang; Laurence Haren; Mireille Bétermier; Robert Walczak; Michael Chandler

1996-01-01

96

Selective synthesis of a [32]octaphyrin(1.0.1.0.1.0.1.0) bis(palladium) complex by a metal-templated strategy.  

PubMed

A shapely figure: A [32]octaphyrin(1.0.1.0.1.0.1.0) bis[palladium(II)] complex was selectively obtained through a metal-templated intermolecular homocoupling of a ?,?'-dibromodipyrrin palladium(II) complex without formation the norcorrole. The weak antiaromatic character of the figure-eight [32]octaphyrin(1.0.1.0.1.0.1.0) system has been elucidated by spectroscopic measurements and DFT calculations. PMID:24155170

Kido, Hiromitsu; Shin, Ji-Young; Shinokubo, Hiroshi

2013-12-16

97

ON THE ALGEBRAIC COMPONENTS OF THE SL(2,C) CHARACTER VARIETIES OF KNOT EXTERIORS  

Microsoft Academic Search

We show that if a knot exterior satisfies certain conditions, then it has finite cyclic coverings with arbitrarily large numbers of nontrivial algebraic components in their SL2(C)-character varieties (Theorem A). As an example, these conditions hold for hy- perbolic punctured torus bundles over the circle (Theorem B). We investigate in more detail the finite cyclic covers of the figure-eight knot

S. BOYER; E. LUFT; X. ZHANG

98

Development of a high-Performance MALDI-TOF mass spectrometer utilizing a spiral ion trajectory  

Microsoft Academic Search

A novel MALDI-TOF mass spectrometer that utilizes a spiral ion trajectory was developed. In this mass spectrometer, the ions\\u000a sequentially passed through four toroidal electrostatic sectors and revolved along a figure-eight-shaped orbit on a particular\\u000a projection plane. Each toroidal electrostatic sector had eight stories, and during multiple revolutions, the ion trajectory\\u000a shifted perpendicular to the projection plane in every cycle,

Takaya Satoh; Takafumi Sato; Jun Tamura

2007-01-01

99

Collection of Remarkable Three-Body Motions  

NSDL National Science Digital Library

This collection of EJS models shows the motions of three or more bodies attracted to one another by gravitational forces. The following applets are included in the collection: Restricted three-body problem - a satellite in the binary planet system Examples of the restricted three-body problem (in two frames of reference) Figure-eight periodic planar three-body motion Figure-eight three-body motion in two frames of reference Variations of figure-eight planar three-body motion Three-body motions in the equilateral configuration Regular planar motions of four bodies of equal masses These Java applets allow us to observe fascinating trajectories of three-body motions that delight the eye and challenge our intuition. However, among the great variety of extremely complex motions there exist a finite subset of very simple regular motions. Some of these regular motions are also illustrated in this collection. EJS applets on this site were created with EJS version 2.0 and are not compatible with the latest version of EJS.

Butikov, Eugene

2010-01-28

100

Cooperation of Intracellular Nadh-Oxidation Systems.  

National Technical Information Service (NTIS)

In model experiments the authors examined cross-connections with the main pathway of the respiratory chain in mitochondria. They ascertained reactions between the soluble diaphorases of the cytoplasm and the mitochondria. At the same time, they traced the...

C. Wagenknecht S. Rapoport

1965-01-01

101

46 CFR 130.130 - Steering on OSVs of less than 100 gross tons.  

Code of Federal Regulations, 2013 CFR

... (j) Each vessel with duplicate (parallel but cross-connected) power systems... (1) Control of the subordinate parallel system is located at the steering-control...main steering gear when the subordinate parallel system is not in operation;...

2013-10-01

102

Investigation of Peptide Charts of Enterobacteriaceae Allergens in Connection with Allergenic Cross Reactions.  

National Technical Information Service (NTIS)

The presence of antigenic cross connections in representatives of Enterobacteriaceae genera is an acknowledged fact. The relationship between representatives of Enterobacteriaceae affects the nature of the allergic sensitization of the macroorganisms infe...

N. I. Shapiro N. P. Denisova

1973-01-01

103

Calcium transient dynamics and the mechanisms of ventricular vulnerability to single premature electrical stimulation in Langendorff-perfused rabbit ventricles  

PubMed Central

BACKGROUND Single strong premature electrical stimulation (S2) may induce figure-eight reentry. We hypothesize that Ca current-mediated slow-response action potentials (APs) play a key role in the propagation in the central common pathway (CCP) of the reentry. METHODS We simultaneously mapped optical membrane potential (Vm) and intracellular Ca (Cai) transients in isolated Langendorff-perfused rabbit ventricles. Baseline pacing (S1) and a cathodal S2 (40 – 80 mA) were given at different epicardial sites with a coupling interval of 135 ± 20 ms. RESULTS In all 6 hearts, S2 induced graded responses around the S2 site. These graded responses propagated locally toward the S1 site and initiated fast APs from recovered tissues. The wavefront then circled around the refractory tissue near the site of S2. At the side of S2 opposite to the S1, the graded responses prolonged AP duration while the Cai continued to decline, resulting in a Cai sinkhole (an area of low Cai). The Cai in the sinkhole then spontaneously increased, followed by a slow Vm depolarization with a take-off potential of ?40 ± 3.9 mV, which was confirmed with microelectrode recordings in 3 hearts. These slow-response APs then propagated through CCP to complete a figure-eight reentry. CONCLUSION We conclude that a strong premature stimulus can induce a Cai sinkhole at the entrance of the CCP. Spontaneous Cai elevation in the Cai sinkhole precedes the Vm depolarization, leading to Ca current-mediated slow propagation in the CCP. The slow propagation allows more time for tissues at the other side of CCP to recover and be excited to complete figure-eight reentry.

Hayashi, Hideki; Kamanu, Santosh Dora; Ono, Norihiko; Kawase, Ayaka; Chou, Chung-Chuan; Weiss, James N.; Karagueuzian, Hrayr S.; Lin, Shien-Fong; Chen, Peng-Sheng

2009-01-01

104

The Analemma  

NSDL National Science Digital Library

This site by Jon Kahl of the University of Wisconsin-Milwaukee provides an explanation of the popular photograph of the sun making an analemma (figure eight shape) taken by Dennis di Cicco. For the image shown, the sun's position in the sky was filmed at exactly the same time of day on 44 days throughout the course of one year to form an analemma. A clear explanation of how the analemma figure results and of how it can be used as a miniature almanac is also included.

Kahl, Jon

2008-05-26

105

Flexible polyvinyl chloride neutron guides for transporting ultracold and very cold neutrons  

SciTech Connect

The transmission of ultracold neutrons (UCNs) through flexible polyvinyl chloride (PVC) tubes with lengths of up to 3 m and an internal diameter of 6-8 mm has been studied. High UCN transmission is found even for arbitrarily bent tubes (single bend, double bend, triple bend, figure eight, etc.). The transmission can be improved significantly by coating the inner surface of the tube with a thin layer of liquid fluorine polymer. The prospects of these neutron guides in fundamental and applied research are discussed.

Arzumanov, S. S., E-mail: sarzumanov@yandex.ru; Bondarenko, L. N. [Russian Research Center Kurchatov Institute (Russian Federation); Geltenbort, P. [Institut Laue-Langevin (France); Morozov, V. I. [Russian Research Center Kurchatov Institute (Russian Federation); Nesvizhevsky, V. V. [Institut Laue-Langevin (France); Panin, Yu. N.; Strepetov, A. N.; Chuvilin, D. Yu. [Russian Research Center Kurchatov Institute (Russian Federation)

2011-12-15

106

Demonstration of High Photon Yields and Nonlinearity in Relativistic Thomson Scattering  

SciTech Connect

We present a progress report on the BNL's experiment on Thomson scattering from 60 MeV electrons in a counter-propagating terawatt CO2 laser beam. The measured x-ray yield averages to one photon per electron within the laser/e-beam overlap region. The observed changes in the spectral and polar distributions of the x-ray beam with the increase of the laser intensity mark the onset of a strong nonlinearity. This indicates that electron's oscillation in the laser field transforms to the figure-eight trajectory.

Pogorelsky, I. V.; Babzien, M.; Ben-Zvi, I.; Kusche, K.; Pavlishin, I. V.; Siddons, D. P.; Yakimenko, V. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Cline, D.; Zhou, F. [University of California at Los Angeles, Los Angeles, CA 90095 (United States); Hirose, T. [Waseda University, Shinjuku-ku, Tokyo 169-8555 (Japan); Kamiya, Y.; Kumita, T. [Tokyo Metropolitan University, Hachioji, Tokyo 192-0397 (Japan); Omori, T.; Urakawa, J.; Yokoya, K. [High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan)

2006-11-27

107

Requirement of IS911 replication before integration defines a new bacterial transposition pathway  

PubMed Central

Movement of transposable elements is often accompanied by replication to ensure their proliferation. Replication is associated with both major classes of transposition mechanisms: cut-and-paste and cointegrate formation (paste-and-copy). Cut-and-paste transposition is often activated by replication of the transposon, while in cointegrate formation replication completes integration. We describe a novel transposition mechanism used by insertion sequence IS911, which we call copy-and-paste. IS911 transposes using a circular intermediate (circle), which then integrates into a target. We demonstrate that this is derived from a branched intermediate (figure-eight) in which both ends are joined by a single-strand bridge after a first-strand transfer. In vivo labelling experiments show that the process of circle formation is replicative. The results indicate that the replication pathway not only produces circles from figure-eight but also regenerates the transposon donor plasmid. To confirm the replicative mechanism, we have also used the Escherichia coli terminators (terC) which, when bound by the Tus protein, inhibit replication forks in a polarised manner. Finally, we demonstrate that the primase DnaG is essential, implicating a host-specific replication pathway.

Duval-Valentin, G; Marty-Cointin, B; Chandler, M

2004-01-01

108

Requirement of IS911 replication before integration defines a new bacterial transposition pathway.  

PubMed

Movement of transposable elements is often accompanied by replication to ensure their proliferation. Replication is associated with both major classes of transposition mechanisms: cut-and-paste and cointegrate formation (paste-and-copy). Cut-and-paste transposition is often activated by replication of the transposon, while in cointegrate formation replication completes integration. We describe a novel transposition mechanism used by insertion sequence IS911, which we call copy-and-paste. IS911 transposes using a circular intermediate (circle), which then integrates into a target. We demonstrate that this is derived from a branched intermediate (figure-eight) in which both ends are joined by a single-strand bridge after a first-strand transfer. In vivo labelling experiments show that the process of circle formation is replicative. The results indicate that the replication pathway not only produces circles from figure-eight but also regenerates the transposon donor plasmid. To confirm the replicative mechanism, we have also used the Escherichia coli terminators (terC) which, when bound by the Tus protein, inhibit replication forks in a polarised manner. Finally, we demonstrate that the primase DnaG is essential, implicating a host-specific replication pathway. PMID:15359283

Duval-Valentin, G; Marty-Cointin, B; Chandler, M

2004-10-01

109

A biomechanical comparison of four reconstruction techniques for the medial collateral ligament-deficient elbow.  

PubMed

The initial strength of the intact medial collateral ligament (MCL) of the elbow and the strength of 4 reconstruction techniques were compared. Twenty cadaveric upper extremities were mounted in a custom jig with the elbow at 90 degrees , and a pneumatic cyclic valgus loading protocol was used. The mean peak load to failure was 142.5+/-39.4 N for the intact ligaments and 53.0+/-9.5 N for the docking reconstructions, 52.5+/-10.4 N for the EndoButton reconstructions, 41.0+/-16.0 N for the interference screw reconstructions, and 33.3+/-7.1 N for the figure-eight reconstructions. The peak load to failure of the MCL reconstructions was inferior compared with the intact ligament (P<.001). No difference in strength was found between the docking and single-strand medial collateral reconstruction with the use of an EndoButton for ulnar fixation (P>.05, beta=.14). Both of these reconstruction methods were stronger than the interference screw or figure-eight technique (P<.004). The optimal fixation method for a single-strand MCL reconstruction may require improved interference screws or a modified EndoButton procedure. PMID:15789016

Armstrong, April D; Dunning, Cynthia E; Ferreira, Louis M; Faber, Kenneth J; Johnson, James A; King, Graham J W

2005-01-01

110

A decomposition approach to assign spare channels in self-healing networks  

Microsoft Academic Search

Intelligent transmission network elements such as digital cross connect systems and add\\/drop multiplexers enable network restoration by dynamic reconfiguration of the network during failure events. Fast line and path restoration is possible by pre-assigning spare capacity to network links. The paper suggests a decomposition approach for the task of finding an economic placement of spare channels in trunk networks to

Meir Herzberg

1993-01-01

111

The World-Wide Web as a Super-Brain: from metaphor to model  

Microsoft Academic Search

ticular has been characterized by the explosive develop- ment of many-to-many communication networks. Where- as the traditional communication media link sender and receiver directly, networked media have multiple cross- connections between the different channels, allowing complex sets of data from different sources to be integrated before being delivered to the receivers. For example, a newsgroup discussion on the Internet will

Francis Heylighen; Johan Bollen

1996-01-01

112

Structural states in the Z band of skeletal muscle correlate with states of active and passive tension  

Microsoft Academic Search

In skeletal muscle Z bands, the ends of the thin contractile filaments interdigitate in a tetragonal array of axial filaments held together by periodically cross-connecting Z filaments. Changes in these two sets of filaments are responsi- ble for two distinct structural states observed in cross section, the small-square and basketweave forms. We have examined Z bands and A bands in

MARGARET A. GOLDSTEIN; LLOYD H. MICHAEL; JOHN P. SCHROETER; RONALD L. SASS

1988-01-01

113

A fast distributed network restoration algorithm  

Microsoft Academic Search

The authors present a fast distributed network restoration algorithm for restoring disrupted traffic in a digital cross-connect system (DCS) based fiber network due to fiber span cut. The proposed algorithm is based on a two-prong approach where both disrupted ends simultaneously send out restore messages as opposed to the conventional approaches where one end is selected as the sender and

C. Edward Chow; John Bicknell; Steve McCaughey; Sami Syed

1993-01-01

114

IP over WDM network traffic engineering approaches  

Microsoft Academic Search

The wide spread deployment of DWDM and reconfigurable optical cross-connect equipment gives rise to a new generation of IP over WDM networks. These network combine gigabit and terabit IP routers with WDM switching and transmission systems to create a more flexible and dynamic network. As these networks grow, there is an urgent need to develop and implement new traffic engineering

J. Y. Wei

2002-01-01

115

WATERBORNE PATHOGEN INVASIONS: A CASE FOR WATER QUALITY PROTECTION IN DISTRIBUTION PROTECTION IN DISTRIBUTION  

EPA Science Inventory

No degree of treatment will insure the delivery of a safe water supplyto the consumer's tap when the distribution system is subject to cross-connections water pressure losses, frequent line breaks, open reservoirs and infrastructure deterioration. n one recent U.S. outbreak, wate...

116

The Advent of WDM and the All-Optical Network: A Reality Check.  

ERIC Educational Resources Information Center

Discussion of the telecommunications industry focuses on WDM (wavelength division multiplexing) as a solution for dealing with capacity constraints. Highlights include fiber optic technology; cross-connecting and switching wavelengths; SONET (Synchronous Optical Network) and wavelength networking; and optical TDM (Time Division Multiplexing). (LRW)

Lutkowitz, Mark

1998-01-01

117

Waterworks Operator Training Manual.  

ERIC Educational Resources Information Center

Sixteen self-study waterworks operators training modules are provided. Module titles are the following: basic mathematics, basic chemistry, analysis procedures, microbiology, basic electricity, hydraulics, chlorination, plant operation, surface water, ground water, pumps, cross connections, distribution systems, safety, public relations, and…

Missouri Univ., Columbia. Instructional Materials Lab.

118

MICROBIAL GROWTH IN DISTRIBUTION SYSTEMS  

EPA Science Inventory

Drinking water is not sterile. Microbes are commonly found in delivered water. Some survive treatment, while others may be introduced due to cross connections, line breaks, or by other means. Biofilm forms in drinking water pipes when bacteria and other organisms adhere to pip...

119

LAND USE AND SEASONAL EFFECTS ON URBAN STORMWATER RUNOFF MICROORGANISM CONCENTRATIONS  

EPA Science Inventory

Stormwater samples collected from storm sewers draining small municipal separate storm sewer systems shown to be free of cross connections within an urban watershed dominated by a single land use were analyzed for pathogens (Pseudomonas aeruginosa and Staphylococcus aureus) and i...

120

Comparison of major parameters in electrodynamic and electromagnetic levitation transport systems  

NASA Astrophysics Data System (ADS)

The study compiles quantitative design information that can be used in selecting a high-speed magnetic levitation system. Analytic models were developed for three configurations of electromagnetic (EMS) and three electrodynamic (EDS) systems, and for linear induction and synchronous motors. The models permit comparisons based on consistent assumptions. The following results indicate that the hoped-for advantages of EDS are difficult to realize: (1) all of the systems studied require smooth guideways to achieve acceptable ride quality unless active control techniques are developed; (2) the estimated weight of the superconducting magnets for the EDS systems is surprisingly large and comparable to the weight of the EMS onboard electromagnets; and (3) real power consumption in sheet guideway null flux EDS is similar to EMS when practical configurations and end effects are considered.

Brown, W. S.; Dauwalter, C. R.; Heger, F.; Weinberg, M. S.

1992-09-01

121

Analysis of an electrodynamic maglev system  

SciTech Connect

Electrodynamic systems (EDS's) for maglev have an advantage over electromagnetic systems (EMS's) in that the stability is built into the system. EDS's induce the currents used for levitation and guidance, while EMS's impose those currents with controlled feedback. The movement of a magnet over properly designed EDS coils results in forces to keep the system fixed in the lowest energy or null flux spot. In the past such systems have been examined through two-dimensional boundary element techniques. An approximation to the full three-dimensional time harmonic problem is obtained through LaPlace transform theory after using boundary element methods to predict the mutual coupling of the magnets with the track coils. The analytic solution offers helpful design and operation guidelines.

Davey, K.

1999-09-01

122

The Penguin: A low Reynolds number powered glider for station keeping missions  

NASA Technical Reports Server (NTRS)

The Penguin is a low Reynolds number (approx. 100,000) remotely piloted vehicle (RPV). It was designed to fly three laps indoors around two pylons in a figure-eight course while maximizing loiter time. The Penguin's low Reynolds number mission is an important one currently being studied for possible future flights in the atmospheres of other planets and for specialized military missions. Although the Penguin's mission seemed quite simple at first, the challenges of such low Reynolds number flight have proven to be quite unique. In addition to the constraint of low Reynolds number flight, the aircraft had to be robust in its control, highly durable, and it had to carry a small instrument package. The Penguin's flight plan, concept, performance, aerodynamic design, weight estimation, structural design, propulsion, stability and control, and cost estimate is detailed.

Costello, J. K.; Greene, D. W.; Lee, T. T.; Matier, P. T.; Mccarthy, T. R.; Mcguire, R. J.; Schuette, M. J.

1990-01-01

123

Space Station - An innovative approach to manufacturing development  

NASA Technical Reports Server (NTRS)

The development of the common modules for the planned dual-keel Space Station, which is a figure-eight configuration that requires the use of four common modules linked by six docking nodes in the center of the Station, is examined. The fabrication of the proposed common module designs, which are a four-barrel common module structure built using excess external tank barrel panels (Martin Marietta Michoud Aerospace), and a three-barrel design consisting of 2219 Al skins with a waffle-grid pattern machined on the outer surface (Boeing Aerospace Corporation) is described. The assistance provided by the NASA-Marshall Space Flight Center's Materials and Processes Laboratory, in particular the variable polarity plasma arc welding process, in the development of the common modules is discussed.

Sullivan, Kenneth W.; Bramon, Christopher J.

1987-01-01

124

Subtotal septal reconstruction by using conchal graft.  

PubMed

Loss of the cartilaginous nasal septum, a condition frequently encountered in the practice of nasal surgery, can vary in scale depending on its etiopathogenesis. Previous surgery, trauma, and infection can lead to subtotal absence of the septum with severe functional and aesthetic problems. Use of the auricular concha for reconstructive purposes proves an immediate and effective method making it possible to replace the missing tissue without involving operations of a more invasive nature. The fundamental problem in the use of the auricular concha is making this type of cartilage as similar as possible to the cartilaginous septum, endowing it with the structural strength and straightness required for support and the respiratory function. Surgical procedures with the use of figure-eight sutures and grafts of cartilage harvested from the concha prove capable of performing this major task of morphofunctional transformation. The article describes the phases involved in achieving the set objectives. PMID:24327246

Boccieri, Armando; Marianetti, Tito M

2013-12-01

125

Magnetic Resonance Imaging of time-varying magnetic fields from therapeutic devices  

PubMed Central

While magnetic resonance imaging of static magnetic fields generated by external probes has been previously demonstrated, there is an unmet need to image time-varying magnetic fields, such as those generated by transcranial magnetic stimulators or radiofrequency hyperthermia probes. A method to image such time-varying magnetic fields is introduced in this work. This article presents the theory behind the method and provides proof of concept by imaging time-varying magnetic fields generated by a figure-eight coil inside simple phantoms over a range of frequencies and intensities, using a 7T small animal MRI scanner. The method is able to reconstruct the three-dimensional components of the oscillating magnetic field vector.

Hernandez-Garcia, Luis; Bhatia, Vivek; Prem-Kumar, Krishan; Ulfarsson, Magnus

2013-01-01

126

Nuclear-magnetic-resonance quantum calculations of the Jones polynomial  

SciTech Connect

The repertoire of problems theoretically solvable by a quantum computer recently expanded to include the approximate evaluation of knot invariants, specifically the Jones polynomial. The experimental implementation of this evaluation, however, involves many known experimental challenges. Here we present experimental results for a small-scale approximate evaluation of the Jones polynomial by nuclear magnetic resonance (NMR); in addition, we show how to escape from the limitations of NMR approaches that employ pseudopure states. Specifically, we use two spin-1/2 nuclei of natural abundance chloroform and apply a sequence of unitary transforms representing the trefoil knot, the figure-eight knot, and the Borromean rings. After measuring the nuclear spin state of the molecule in each case, we are able to estimate the value of the Jones polynomial for each of the knots.

Marx, Raimund; Spoerl, Andreas; Pomplun, Nikolas; Schulte-Herbrueggen, Thomas; Glaser, Steffen J. [Department of Chemistry, Technische Universitaet Muenchen, Lichtenbergstr. 4, D-85747 Garching (Germany); Fahmy, Amr [Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115 (United States); Kauffman, Louis [University of Illinois at Chicago, 851 S. Morgan Street, Chicago, Illinois 60607-7045 (United States); Lomonaco, Samuel [University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Myers, John M. [Cruft Laboratory, Harvard University, 19 Oxford Street, Cambridge, Massachusetts 02138 (United States)

2010-03-15

127

Current concepts of ventricular defibrillation.  

PubMed

The aim of this article is to review the current concepts of ventricular defibrillation. We studied the interaction between strong electrical stimulus and cardiac responses in both animal models and in humans. We found that a premature stimulus (S2) of appropriate strength results in figure-eight reentry in vitro by inducing propagated graded responses. The same stimulation protocol induces figure-eight reentry and ventricular fibrillation (VF) in vivo. When the S2 strength and the magnitude of graded responses increase beyond a critical level, the increase in refractoriness at the site of the stimulus becomes so long that the unidirectional block becomes bidirectional block, preventing the formation of reentry (upper limit of vulnerability [ULV]). In other studies, we found that the effects of an electrical stimulation on reentry is in part determined by the timing of the stimulus. A protective zone is present after the induction of VF and after an unsuccessful defibrillation shock during which an electrical stimulus can terminate reentry and protect the heart from VF. These results indicate that the effects of a defibrillation shock is dependent on both the strength and the timing of the shock. Timing is not important in areas where the shock field strength is > or = ULV because the shock terminates all reentry but cannot reinitiate new ones. However, in areas where shock field strength is < ULV, the effects of the shock are determined by the timing of the shock relative to local VF activations. This ULV hypothesis of defibrillation explains the probabilistic nature of ventricular defibrillation. It also indicates that, to achieve a high probability of successful defibrillation, a shock must result in a shock field strength of > or = ULV throughout the ventricles. PMID:9607464

Chen, P S; Swerdlow, C D; Hwang, C; Karagueuzian, H S

1998-05-01

128

Ultrahigh-speed optical signal transmission in point-to-point systems and transparent networks  

NASA Astrophysics Data System (ADS)

We experimentally demonstrate ultra-high-speed (40 Gb/s, 80 Gb/s, and 160 Gb/s) optical signal transmission in point-to-point terrestrial systems and transparent networks built on cross connects and add-drop multiplexers. Without using forward error correction, we demonstrate 40-Gb/s transmission over 2000 km based on a simple system design, 80-Gb/s transmission over 1200 km, and 160-Gb/s transmission over 300 km, all with 100-km terrestrial type transmission span. In addition, a new approach to generating phase-correlated ultra-high-speed signals is introduced. We also demonstrate 40-Gb/s transmission through wavelength-selective optical cross connects spaced by 400 km, as well as 40- and 160-Gb/s signal transmission through a new type optical add-drop multiplexer that can adapt to different data rates.

Su, Yikai

2004-05-01

129

A self-healing network with an economical spare-channel assignment  

Microsoft Academic Search

With the advent of networking technologies intelligent network elements, such as the digital cross-connect system (DCS), will make it possible to dynamically reconfigure a network for restoration purposes. Both restoration control of DCSs and spare-channel design issues are presented, and how they work together so that a fast and economical SONET self-healing network is obtained. In order to achieve fast

Hideki Sakauchi; Y. Nishimura; S. Hasegawa

1990-01-01

130

Self-healing rings in a synchronous environment  

Microsoft Academic Search

An overview of different self-healing network architectures, focusing on ring architectures, is presented. Digital cross-connect systems-based self-healing and diversely routed protection are briefly discussed. Since a typical self-healing network design may use all of the self-healing architectures, a discussion on applications perspectives, illustrating how the various self-healing technologies may best fit in the evolving network, is included

I. Haque; W. Kremer; K. Raychaudhuri

1991-01-01

131

Dynamic bandwidth-allocation and path-restoration in SONET self-healing networks  

Microsoft Academic Search

This paper presents a new scheme for real-time bandwidth allocation and path restoration (BARS) in mesh networks via SONET wideband digital cross-connect systems (WDCSs) in response to demand and load dynamics and link and\\/or node failure(s). The scheme dynamically maximizes bandwidth allocation while ensuring full service restorability. Since the physical network capacity is limited, sometime not all the demand can

A. Gersht; S. Kheradpir; A. Shulman

1996-01-01

132

An algorithm for virtual topology design in WDM optical networks under physical constraints  

Microsoft Academic Search

Although designing a virtual topology for all-optical WDM wide-area networks has been extensively studied and several algorithms have been proposed, these algorithms assume error-free communication between two nodes. However, noises from optical amplifiers and optical cross-connects can degrade the signal, resulting in a nonzero bit-error rate. In this paper, we investigate the effect of physical limitations on the virtual topology

Ji Yon Youe; Seung-Woo Seo

1999-01-01

133

1296-port MEMS transparent optical crossconnect with 2.07 petabit\\/s switch capacity  

Microsoft Academic Search

A 1296-port MEMS transparent optical crossconnect with 5.1dB±1.1dB insertion loss at 1550 nm is reported. Measured worst-case optical crosstalk in a fabric was n38 dB and nominal switching rise\\/fall times were 5 ms. A 2.07 petabit\\/s switch capacity was verified upon cross-connecting a forty-channel by 40 Gb\\/s DWDM data stream through a prototype fabric.

R. Ryf; J. Kim; J. P. Hickey; A. Gnauck; D. Carr; F. Pardo; C. Bolle; R. Frahm; N. Basavanhally; C. Yoh; D. Ramsey; R. Boie; R. George; J. Kraus; C. Lichtenwalner; R. Papazian; J. Gates; H. R. Shea; A. Gasparyan; V. Muratov; J. E. Griffith; J. A. Prybyla; S. Goyal; C. D. White; M. T. Lin; R. Ruel; C. Nijander; S. Arney; D. T. Neilson; D. J. Bishop; P. Kolodner; S. Pau; C. Nuzman; A. Weis; B. Kumar; D. Lieuwen; V. Aksyuk; D. S. Greywall; T. C. Lee; H. T. Soh; W. M. Mansfield; S. Jin; W. Y. Lai; H. A. Huggins; D. L. Barr; R. A. Cirelli; G. R. Bogart; K. Teffeau; R. Vella; H. Mavoori; A. Ramirez; N. A. Ciampa; F. P. Klemens; M. D. Morris; T. Boone; J. Q. Liu; J. M. Rosamilia; C. R. Giles

2001-01-01

134

Dissolved Organic Matter Dynamics in two Suburban Catchments in NE England  

NASA Astrophysics Data System (ADS)

Recent advances in fluorescence spectrophotometry enable rapid and optically precise analysis of river dissolved organic matter (DOM). In this study we investigate the potential of detecting river pollution associated with urban expansion (cross connected sewerage; overloading of combined sewer overflows (CSOs), land use change) using fluorescence and absorbance spectrophotometry, paired with conventional geochemistry, microbiological analyses and 14C/13C isotope fingerprinting of dissolved organic matter, in two small, rural-urban fringe catchments in NE England over the period 2002-present. In the United Kingdom, `suburbia' (post 1945AD) is distinguished by separate sewerage systems and associated issues of cross connections. Results indicate: (1) suburban catchments have a seasonal trend in DOM fluorescence, with a maximum of tryptophan-like fluorescence in summer low flow, indicative of an increased proportion of cross connected sewer inputs, with a statistically significant inverse relationship with discharge. Older `urban' catchments with CSOs exhibit an opposite seasonality, with combined sewerage overflows occurring in winter at high flow due to CSO discharge. (2) Sampling cross connected storm drains for both Escherichia coli. and fluorescence demonstrates a statistically significant relationship. This finding matches laboratory microbial cultures, which have demonstrated that a wide range of environmentally relevant microbes exhibit tryptophan-like fluorescence, and suggests that when coliforms dominate a river or wastewater microbial community then fluorescence intensity could potentially be employed to monitor faecal coliforms in urban waters. (3) 14C/13C fingerprinting of DOM in three contrasting sub-catchments separates urban and industrial DOM sources through positive 13C and `old' 14C.

Baker, A.; Simpson, E.; Bryant, C.

2005-12-01

135

Coupling wavelength assignment in bidirectional lightpath: Is it worth the extra cost?  

Microsoft Academic Search

The introduction of end-to-end (multi hop) optical circuits (lightpaths) is often seen as the natural extension of a point-to-point (single hop) wavelength division multiplexing (WDM) transmission system, spanning across optical cross-connect nodes. Conventionally, a bidirectional lightpath (whether single or multi hop) comprises two lambda channels in fibers with opposite directions of signal propagation, which are assigned the same wavelength. This

Arularasi Sivasankaran; Miguel Razo; Shreejith Billenahalli; Wanjun Huang; Limin Tang; Marco Tacca; Andrea Fumagalli

2010-01-01

136

Digital-data receiver synchronization method and apparatus  

DOEpatents

Digital data receiver synchronization is provided with composite phase-frequency detectors, mutually cross-connected comparison feedback or both to provide robust reception of digital data signals. A single master clock can be used to provide frequency signals. Advantages can include fast lock-up time in moderately to severely noisy conditions, greater tolerance to noise and jitter when locked, and improved tolerance to clock asymmetries.

Smith, Stephen F. (Loudon, TN) [Loudon, TN; Turner, Gary W. (Clinton, TN) [Clinton, TN

2009-09-08

137

Collagen fibre arrangement and functional crimping pattern of the medial collateral ligament in the rat knee  

Microsoft Academic Search

Ligaments have been described as multifascicular structures with collagen fibres cross-connecting to each other or running\\u000a straight and parallel also showing a waviness or crimping pattern playing as a shock absorber\\/recoiling system during joint\\u000a motions. A particular collagen array and crimping pattern in different ligaments may reflect different biomechanical roles\\u000a and properties. The aim of the study was to relate

Marco Franchi; Marilisa Quaranta; Maria Macciocca; Luisa Leonardi; Vittoria Ottani; Paolo Bianchini; Alberto Diaspro; Alessandro Ruggeri

2010-01-01

138

The efficiency of bridges in a crack  

Microsoft Academic Search

Bridges are cross connections in a crack that contract its faces behind the crack tip. They appear because of the inhomogeneity of the material or differences in the kinematics of fracture. We obtained a general solution to the nonlinear singular integral equation that relates the crack opening h(x) to the stress caused by bridges p(x) and determined the stress-intensity factor

M. A. Shtremel

2007-01-01

139

The efficiency of bridges in a crack  

Microsoft Academic Search

Bridges are cross connections in a crack that contract its faces behind the crack tip. They appear because of the inhomogeneity\\u000a of the material or differences in the kinematics of fracture. We obtained a general solution to the nonlinear singular integral\\u000a equation that relates the crack opening h(x) to the stress caused by bridges p(x) and determined the stress-intensity factor

M. A. Shtremel’

2007-01-01

140

On the physical and logical topology design of large-scale optical networks  

Microsoft Academic Search

We consider the problem of designing a network of optical cross-connects (OXCs) to provide end-to-end lightpath services to large numbers of label switched routers (LSRs). We present a set of heuristic algorithms to address the combined problem of physical topology design (i.e., determine the number of OXCs required and the fiber links among them) and logical topology design (i.e., determine

Yufeng Xin; George N. Rouskas; Harry G. Perros

2003-01-01

141

Greening the availability design of optical WDM networks  

Microsoft Academic Search

Tremendously increasing bandwidth demands on the Internet require high transmission capacity and reliable end-to-end connections which are offered by optical WDM networks. Huge bandwidth demands of the applications cause rising energy consumption at the optical cross-connects which contributes a significant portion of the total electricity consumption. In this paper, we study the availability design of optical WDM networks in an

Burak Kantarci; Hussein T. Mouftah

2010-01-01

142

Performance analysis and optimization of various MG-OXCs multi-granularity WDM optical networks based on waveband switching  

Microsoft Academic Search

Multi-granularity optical cross-connects (MG-OXC) is proposed as a promising technique to reduce the cost of the optical nodes in the wavelength division multiplexing (WDM) optical networks. In this paper, we use the on-line Maximize the Number of Waveband Route (MNWR) algorithm to evaluate the performance and optimize the design of multi-granularity optical WDM networks based on two different MG-OXCs: the

Yongmin Qi; Yi Zhu; Tianshu Wang; Xuefang Zhou; Sheng Qian; Qiliang Li

2008-01-01

143

Implementation of physical transmission impairments constraint optical multicasting in translucent WDM mesh networks  

Microsoft Academic Search

A translucent multicasting scheme based on sparsely placed signal re-generable translucent multicasting capable optical cross connect (tMC-OXC) nodes is proposed to provide signal-quality guaranteed multicasting services. We propose a tMC-OXC architecture capable of transparent unicasting and electronic multicasting. The electronic multicasting devices are also used to regenerate the impaired signals. A regeneration weight based MC-OXC nodes placement strategy is designed

Yunfeng Peng; Yaohui Jin; Peigang Hu; Weisheng Hu; Yongmin Qi

2005-01-01

144

Impairment-aware dynamic RWA algorithm in multi-granularity WDM optical networks  

Microsoft Academic Search

In practical multi-granularity WDM optical networks, optical signals will be degraded due to impairments mainly introduced by a number of multi-granularity optical cross-connects (MG-OXC) and fiber links. Even worse, transmission impairments will make the bit-error rate to be unacceptable. We investigate the impact of transmission impairments on optical signal quality in multi-granularity WDM optical networks. A novel dynamic impairment-aware RWA

Yongmin Qi; Yi Zhu; Tianshu Wang; Xuefang Zhou; Sheng Qian; Qiliang Li

2008-01-01

145

Lyman-Alpha Line Center Continuum as a Diagnostic of the Winds of Bright a Stars  

NASA Astrophysics Data System (ADS)

A relatively high residual continuum has been observed in themiddle of the H Lyman alpha line of Sirius A (Cycle 1 GHRSobservations) while classical models predict a null flux atline center. From very simplified calculations it appears thatthe scattering of photospheric Lyman alpha photons byexpanding neutral H associated with a wind would produce aline center continuum of the order of what is observed, whenthe mass loss and the terminal velocity of the wind aresimilar to those independantly deduced from the small blueshifted absorptions in the magnesium lines also observed withthe GHRS. We then suggest that, through appropriatesophisticated radiative transfer models,the H Lyman alphacontinuum and line shape of the A type stars can be used asvaluable tracers of the winds generated by these stars,otherwise very poorly detectable. This method , however, isrestricted to very bright objects for the line bottom to bewell detected. We propose to perform high signal-to-noiseratio GHRS observations of two other very bright A-type starsto search for similar characteristics at Lyman alpha, withalso a new observation of Sirius A with higher Signal to Noisewith the aim of disentangling stellar line asymetries frominterstellar absorptions.

Lallement, Rosine

1996-07-01

146

Novel cryogen-free actively shielded superconducting magnets for maglev vehicles. Final report, August 1991-June 1992  

SciTech Connect

The report presents the results of a research effort into the design of a shielded superconducting magnet system for a maglev vehicle. The magnet design is based on a novel cryogen-free technology which allows operation without the use of any cryogenic fluids. This is accomplished by the use of a two-stage Gifford-McMahon (G-M) cryogenic refrigerator to provide cooling of the coil and a single cryostat thermal radiation shield by conduction. The design operating temperature of the magnet is 7.5 K, and that of the shield is 43 K. The magnet is wound with a tape form of niobium tin superconductor which allows operation at a module current density of 8100 A/sq cm at a flux density of 3.4 T at the 7.5 K temperature with a margin of 4.5 K to critical temperature. The magnet design is coupled with a linear synchronous motor and null-flux sidewall levitation system to provide a workable maglev system design. Costs for several components of the design, including coils and cryostat, shielding, and power conditioning apparatus are estimated.

Vermilyea, M.E.

1992-06-01

147

Spatial Light Modulators as Optical Crossbar Switches  

NASA Technical Reports Server (NTRS)

A proposed method of implementing cross connections in an optical communication network is based on the use of a spatial light modulator (SLM) to form controlled diffraction patterns that connect inputs (light sources) and outputs (light sinks). Sources would typically include optical fibers and/or light-emitting diodes; sinks would typically include optical fibers and/or photodetectors. The sources and/or sinks could be distributed in two dimensions; that is, on planes. Alternatively or in addition, sources and/or sinks could be distributed in three dimensions -- for example, on curved surfaces or in more complex (including random) three-dimensional patterns.

Juday, Richard

2003-01-01

148

Propagation of all-optical crosstalk attack in transparent optical networks  

NASA Astrophysics Data System (ADS)

Transparent optical network (TON) is now rapidly booming to be popular, and a threat of an all-optical crosstalk attack with high power will emerge. In this paper, the penalty of crosstalk attack propagation, including intrachannel crosstalk inside the optical cross-connects, as well as direct and indirect interchannel crosstalk within fibers, is evaluated. Our work has proved that these crosstalk attacks do propagate in the TON but with limited propagation stages, which will be useful for the planning, management, and design of TON.

Peng, Yunfeng; Sun, Zeyu; Du, Shu; Long, Keping

2011-08-01

149

Torus Knots and Links from Eikonal Equations and Knot Invariants for Classification of Atoms  

NASA Astrophysics Data System (ADS)

The history of knot theory and physics has a deep roots. It started by Lord Kelvin, in 1867, when he conjectured that atoms were knotted vortex tubes of ether. In 1997, Faddeev and Niemi suggested that knots might exist as stable soliton solution in a simple three dimensional classical field theory. That opening up a wide range of possible applications in physics. In this work we consider the Eikonal equation, which is a partial differential equation describing the traveltime propagation, which is an important part of seismic imaging algorithms. We will follow the work of Wereszczynski of solving the Eikonal equation in cylindrical coordinates. We show that only torus knots and links do occur, so figure eight knot does not occur. We show that these solutions are not unique, which means the possible occurrence of the same knot type for different configurations. Using the idea of framed knots, it is shown that two Eikonal knots are equivalent if and only if they are ambient isotopic as a framed knots, i.e. if and only if they are of the same knot type and of the same twisting number.

Elrifai, E. A.

2008-03-01

150

[Bilateral 23Na MR imaging of the breast and quantification of sodium concentration].  

PubMed

A novel setup for (23)Na MRI, which allows bilateral imaging of the breast, is presented. For this purpose a figure-eight receive-only (23)Na surface coil was developed. For our experiments on three samples with NaCl solutions of different sodium concentrations and two female subjects we used an asymmetric birdcage coil in transmit mode and the developed surface coil for receiving the signal at 3T. Imaging of the samples showed the applicability of the employed normalization method for measuring the distribution of sodium concentration. In a sample of concentration [Na(+)]=51mM we achieved SNR=70 at a nominal isotropic resolution of 2,5mm (TR=66ms, TE=0,6ms, TA=20min). Furthermore we showed that by means of this setup it is possible to quantify the sodium concentration in breast tissue (TSC) of a female subject with an accuracy of 23% (TR=150ms, TE=0,5ms, TA=45min). PMID:23969091

Danisch, Meike; Kalayciyan, Raffi; Wetterling, Friedrich; Schad, Lothar R

2014-03-01

151

Compensation Techniques in Accelerator Physics  

SciTech Connect

Accelerator physics is one of the most diverse multidisciplinary fields of physics, wherein the dynamics of particle beams is studied. It takes more than the understanding of basic electromagnetic interactions to be able to predict the beam dynamics, and to be able to develop new techniques to produce, maintain, and deliver high quality beams for different applications. In this work, some basic theory regarding particle beam dynamics in accelerators will be presented. This basic theory, along with applying state of the art techniques in beam dynamics will be used in this dissertation to study and solve accelerator physics problems. Two problems involving compensation are studied in the context of the MEIC (Medium Energy Electron Ion Collider) project at Jefferson Laboratory. Several chromaticity (the energy dependence of the particle tune) compensation methods are evaluated numerically and deployed in a figure eight ring designed for the electrons in the collider. Furthermore, transverse coupling optics have been developed to compensate the coupling introduced by the spin rotators in the MEIC electron ring design.

Hisham Kamal Sayed

2011-05-31

152

Development of a high-performance MALDI-TOF mass spectrometer utilizing a spiral ion trajectory.  

PubMed

A novel MALDI-TOF mass spectrometer that utilizes a spiral ion trajectory was developed. In this mass spectrometer, the ions sequentially passed through four toroidal electrostatic sectors and revolved along a figure-eight-shaped orbit on a particular projection plane. Each toroidal electrostatic sector had eight stories, and during multiple revolutions, the ion trajectory shifted perpendicular to the projection plane in every cycle, thereby generating a spiral trajectory. The flight path length of one cycle was 2.1 m; therefore, when the ions completed eight cycles, the total flight path length was 17 m. By adopting an ion optical system that had a flight path length five times longer than that in the commonly used reflectron ion optical system, the mass dependence on the mass resolving power was reduced, while improving the mass accuracy of the mass measurements. The basic performance of the system was tested by using standard peptides or the tryptic digest of bovine serum albumin. A mass resolving power of 80,000 (full width at half maximum) was achieved at m/z = 2564 (ACTH18-39). An improved mass accuracy less than 2 ppm was realized over a wide m/z range of 500 to 3000 by correction using one or two internal standard substances. PMID:17512213

Satoh, Takaya; Sato, Takafumi; Tamura, Jun

2007-07-01

153

Spatiotemporal topology and temporal sequence identification with an adaptive time-delay neural network  

NASA Astrophysics Data System (ADS)

Inspired from the time delays that occur in neurobiological signal transmission, we describe an adaptive time delay neural network (ATNN) which is a powerful dynamic learning technique for spatiotemporal pattern transformation and temporal sequence identification. The dynamic properties of this network are formulated through the adaptation of time-delays and synapse weights, which are adjusted on-line based on gradient descent rules according to the evolution of observed inputs and outputs. We have applied the ATNN to examples that possess spatiotemporal complexity, with temporal sequences that are completed by the network. The ATNN is able to be applied to pattern completion. Simulation results show that the ATNN learns the topology of a circular and figure eight trajectories within 500 on-line training iterations, and reproduces the trajectory dynamically with very high accuracy. The ATNN was also trained to model the Fourier series expansion of the sum of different odd harmonics. The resulting network provides more flexibility and efficiency than the TDNN and allows the network to seek optimal values for time-delays as well as optimal synapse weights.

Lin, Daw-Tung; Ligomenides, Panos A.; Dayhoff, Judith E.

1993-08-01

154

Studies on magnetism and bioelectromagnetics for 45 years: from magnetic analog memory to human brain stimulation and imaging.  

PubMed

Forty-five years of studies on magnetism and bioelectromagnetics, in our laboratory, are presented. This article is prepared for the d'Arsonval Award Lecture. After a short introduction of our early work on magnetic analog memory, we review and discuss the following topics: (1) Magnetic nerve stimulation and localized transcranial magnetic stimulation (TMS) of the human brain by figure-eight coils; (2) Measurements of weak magnetic fields generated from the brain by superconducting quantum interference device (SQUID) systems, called magnetoencephalography (MEG), and its application in functional brain studies; (3) New methods of magnetic resonance imaging (MRI) for the imaging of impedance of the brain, called impedance MRI, and the imaging of neuronal current activities in the brain, called current MRI; (4) Cancer therapy and other medical treatments by pulsed magnetic fields; (5) Effects of static magnetic fields and magnetic control of cell orientation and cell growth; and (6) Effects of radio frequency magnetic fields and control of iron ion release and uptake from and into ferritins, iron cage proteins. These bioelectromagnetic studies have opened new horizons in magnetism and medicine, in particular for brain research and treatment of ailments such as depression, Parkinson's, and Alzheimer's diseases. PMID:22012916

Ueno, Shoogo

2012-01-01

155

Disturbance of visual search by stimulating to posterior parietal cortex in the brain using transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

In this study, we applied a transcranial magnetic stimulation (TMS) to investigate the temporal aspect for the functional processing of visual attention. Although it has been known that right posterior parietal cortex (PPC) in the brain has a role in certain visual search tasks, there is little knowledge about the temporal aspect of this area. Three visual search tasks that have different difficulties of task execution individually were carried out. These three visual search tasks are the ``easy feature task,'' the ``hard feature task,'' and the ``conjunction task.'' To investigate the temporal aspect of the PPC involved in the visual search, we applied various stimulus onset asynchronies (SOAs) and measured the reaction time of the visual search. The magnetic stimulation was applied on the right PPC or the left PPC by the figure-eight coil. The results show that the reaction times of the hard feature task are longer than those of the easy feature task. When SOA=150 ms, compared with no-TMS condition, there was a significant increase in target-present reaction time when TMS pulses were applied. We considered that the right PPC was involved in the visual search at about SOA=150 ms after visual stimulus presentation. The magnetic stimulation to the right PPC disturbed the processing of the visual search. However, the magnetic stimulation to the left PPC gives no effect on the processing of the visual search.

Iramina, Keiji; Ge, Sheng; Hyodo, Akira; Hayami, Takehito; Ueno, Shoogo

2009-04-01

156

Comparison of current distributions in electroconvulsive therapy and transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

We compared current density distributions in electroconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS) by numerical calculations. The model consisted of an air region and three types of tissues with different conductivities representing the brain, the skull, and the scalp. In the ECT model, electric currents were applied through electrodes with a voltage of 100 V. In the TMS model, a figure-eight coil (6 cm diameter per coil) was placed on the vertex of the head model. An alternating current with a peak intensity of 3.0 kA and a frequency of 4.2 kHz was applied to the coil. The maximum current densities inside the brain in ECT (bilateral electrode position) and TMS were 234 and 322 A/m2, respectively. The results indicate that magnetic stimulators can generate comparable current densities to ECT. While the skull significantly affected current distributions in ECT, TMS efficiently induced eddy currents in the brain. In addition, TMS is more beneficial than ECT because the localized current distribution reduces the risk of adverse side effects.

Sekino, Masaki; Ueno, Shoogo

2002-05-01

157

The vertical disk structure of the edge-on spiral galaxy NGC 3079  

NASA Technical Reports Server (NTRS)

NGC 3079 is an edge-on SB(s)c galaxy at a redshift of 1225 km/s relative to the Local Group. Earlier researchers found a spectacular 'figure-eight' radio structure aligned along the minor axis of the galaxy, centered on the nucleus, and extending 3 kpc above and below the plane. The geometry of this structure and the evidence of unusually high nuclear gas velocities suggest that a wind-type outflow from the nucleus is taking place. The disk of NGC 3079 is also remarkable: it is extremely rich in H 2 regions and is the only unambiguous example of a galaxy outside M31 and our own Galaxy to exhibit 'Heiles-like' shells. Other researchers have also identified a nebulosity with a ragged X-shaped morphology formed by a system of lumpy filaments with individual lengths of 3 - 5 kpc. They suggest that this material is ambient halo gas entrained into the boundary layers of the nuclear outflow. The complex structure of the line emission in NGC 3079 makes this object an ideal target for an imaging spectroscopic study. The present paper reports the preliminary results of such a study.

Veilleux, S.; Bland-Hawthorn, Jonathan; Cecil, G.; Tully, R. B.

1993-01-01

158

Unusual properties of two branched RNA's with circular and linear components.  

PubMed

Irradiation with ultraviolet light was used to create two nonlinear RNA molecules. Circular potato spindle tuber viroid (PSTV) RNA was crosslinked at a single site to generate a figure eight-shaped molecule; 5S rRNA from HeLa cells was transformed into an alpha-shaped molecule with a small circular element and two arms (1). Crosslinked RNA's could be separated from their untreated counterparts by electrophoresis in polyacrylamide gels containing urea. The gel mobility of crosslinked PSTV was not altered by boiling, treatment with E. coli RNase III or glyoxalation. However, mild nuclease digestion ("nicking") produced derivatives which migrated more slowly than the starting material in gels of certain polyacrylamide concentrations, but not in others. Limited nuclease digestion of crosslinked 5S rRNA did not generate any detectable products with reduced mobility in the gels tested. Thus, the ability of the "nicking assay" to reveal circular elements within nonlinear RNA's can vary depending upon the composition of the gel chosen for analysis and on the size of the circular element relative to the rest of the molecule. PMID:2410857

Branch, A D; Benenfeld, B J; Robertson, H D

1985-07-11

159

The discrepancy between human peripheral nerve chronaxie times as measured using magnetic and electric field stimuli: the relevance to MRI gradient coil safety  

NASA Astrophysics Data System (ADS)

Peripheral nerve stimulation (PNS) resulting from electric fields induced from the rapidly changing magnetic fields of gradient coils is a concern in MRI. Nerves exposed to either electric fields or changing magnetic fields would be expected to display consistent threshold characteristics, motivating the direct application of electric field exposure criteria from the literature to guide the development of gradient magnetic field exposure criteria for MRI. The consistency of electric and magnetic field exposures was tested by comparing chronaxie times for electric and magnetic PNS curves for 22 healthy human subjects. Electric and magnetic stimulation thresholds were measured for exposure of the forearm using both surface electrodes and a figure-eight magnetic coil, respectively. The average chronaxie times for the electric and magnetic field conditions were 109 ± 11 µs and 651 ± 53 µs (±SE), respectively. We do not propose that these results call into question the basic mechanism, namely that rapidly switched gradient magnetic fields induce electric fields in human tissues, resulting in PNS. However, this result does motivate us to suggest that special care must be taken when using electric field exposure data from the literature to set gradient coil PNS safety standards in MRI.

Recoskie, Bryan J.; Scholl, Timothy J.; Chronik, Blaine A.

2009-10-01

160

Neural network training by integration of adjoint systems of equations forward in time  

NASA Technical Reports Server (NTRS)

A method and apparatus for supervised neural learning of time dependent trajectories exploits the concepts of adjoint operators to enable computation of the gradient of an objective functional with respect to the various parameters of the network architecture in a highly efficient manner. Specifically, it combines the advantage of dramatic reductions in computational complexity inherent in adjoint methods with the ability to solve two adjoint systems of equations together forward in time. Not only is a large amount of computation and storage saved, but the handling of real-time applications becomes also possible. The invention has been applied it to two examples of representative complexity which have recently been analyzed in the open literature and demonstrated that a circular trajectory can be learned in approximately 200 iterations compared to the 12000 reported in the literature. A figure eight trajectory was achieved in under 500 iterations compared to 20000 previously required. The trajectories computed using our new method are much closer to the target trajectories than was reported in previous studies.

Toomarian, Nikzad (inventor); Barhen, Jacob (inventor)

1992-01-01

161

Neural Network Training by Integration of Adjoint Systems of Equations Forward in Time  

NASA Technical Reports Server (NTRS)

A method and apparatus for supervised neural learning of time dependent trajectories exploits the concepts of adjoint operators to enable computation of the gradient of an objective functional with respect to the various parameters of the network architecture in a highly efficient manner. Specifically. it combines the advantage of dramatic reductions in computational complexity inherent in adjoint methods with the ability to solve two adjoint systems of equations together forward in time. Not only is a large amount of computation and storage saved. but the handling of real-time applications becomes also possible. The invention has been applied it to two examples of representative complexity which have recently been analyzed in the open literature and demonstrated that a circular trajectory can be learned in approximately 200 iterations compared to the 12000 reported in the literature. A figure eight trajectory was achieved in under 500 iterations compared to 20000 previously required. Tbc trajectories computed using our new method are much closer to the target trajectories than was reported in previous studies.

Toomarian, Nikzad (Inventor); Barhen, Jacob (Inventor)

1999-01-01

162

High sensitivity magnetic head for a shaft torque sensor  

NASA Astrophysics Data System (ADS)

The structure of a magnetic head used for torque sensing is investigated to seek higher sensitivity with low power consumption. The magnetic head investigated consists of two figure-eight coils embedded in a ferrite core. Torque applied to a magnetostrictive steel shaft makes the magnetic coupling between two coils in the head change positively or negatively depending on the sign and the strength of torque. Two structures, the square shape and the diagonal shape, are analyzed in terms of sensitivity and compared to our previous structure, the circle shape, which is an intermediate of the two in shape. It was found that the diagonal structure is the best choice. With this structure using a 14.6 mm square ferrite core, the applied torque is stably detected with 0.1 W power consumption (excitation condition: 60 kHz, 0.1 A) from a case-hardened steel shaft with an air gap 0.5 mm between head and shaft.

Sasada, I.; Akinaga, M.

2002-05-01

163

Design of a dynamic transcranial magnetic stimulation coil system.  

PubMed

To study the brain activity at the whole-head range, transcranial magnetic stimulation (TMS) researchers need to investigate brain activity over the whole head at multiple locations. In the past, this has been accomplished with multiple single TMS coils that achieve quasi whole-head array stimulation. However, these designs have low resolution and are difficult to position and control over the skull. In this study, we propose a new dynamic whole-head TMS mesh coil system. This system was constructed using several sagittal and coronal directional wires. Using both simulation and real experimental data, we show that by varying the current direction and strength of each wire, this new coil system can form both circular coils or figure-eight coils that have the same features as traditional TMS coils. Further, our new system is superior to current coil systems because stimulation parameters such as size, type, location, and timing of stimulation can be dynamically controlled within a single experiment. PMID:24957390

Ge, Sheng; Jiang, Ruoli; Wang, Ruimin; Chen, Ji

2014-08-01

164

Two-Dimensional Vortex-Induced Vibration of Cable Suspensions  

NASA Astrophysics Data System (ADS)

Resonant responses of suspended elastic cables driven by a steady current are investigated. Phenomenological fluid force models for alternate vortex-shedding are coupled with the nonlinear partial differential equations of cable motion. Decoupled cross-flow and in-line vortex-induced vibrations (VIV) are examined first using linearized and nonlinear cable models. The linearized cable model predicts well the basic characteristics of VIV and the nonlinear cable model captures the hysteresis often observed in experiments. Next, coupled cross-flow and in-line vibrations are evaluated by considering two principal coupling mechanisms: (i) cable structural nonlinearities, and (ii) coupled fluid lift and drag. Attention is focused on a ``worst-case'' resonant response where the natural frequencies for cable modes in the cross-flow and in-line directions are in the same 1:2 ratio as the excitation frequencies associated with lift and drag. The inclusion of cable structural nonlinearities alone leads to coupled responses that differ qualitatively (i.e., in number and stability of periodic motions) when compared to those of the decoupled model. The inclusion of coupled fluid lift and drag produces non-planar ``figure eight'' motions of the cable cross-section that exhibit similar characteristics to those previously measured on spring supported cylinders.

Kim, W.-J.; Perkins, N. C.

2002-02-01

165

PIV Measurements in Model and Full Scale Coal Mines  

NASA Astrophysics Data System (ADS)

The present research focuses on examining effective ventilation in a coal mine using PIV. The purpose of these experiments is to study in detail the flow characteristics in a 1:15 scale mine model and compare it with a full-scale mine to develop effective means of face ventilation in a coal mine. PIV measurements were conducted in the prototype model with various channel geometries with width to height ratios of 1.7 to 4 and length to height ratios of 2 to 5, with and without slabs. Gross separation was observed to occur immediately downstream of the ventilation exit (curtain) in all cases below a critical channel width resulting in a figure eight pattern and drastically reduced face ventilation. PIV measurements taken on a full-scale mine model (6.1 m wide by 18.3 m long) at NIOSH displayed similar flow patterns, including separation immediately downstream of the curtain resulting in inadequate ventilation. In addition to time-averaged and unsteady velocity fields, volumetric flow rates, wall skin friction in the separation region, and possible methods of improved face ventilation are presented.

Rangubhotla, Lavanya; Jacob, Jamey; Wala, Andrew; Taylor, Charles

2002-11-01

166

Cation Chemistry in Baltimore Streams: Another Syndrome Symptom?  

NASA Astrophysics Data System (ADS)

Urban streams are degraded due to a variety of physical and chemical factors including impervious surfaces, sewer cross-connections, and multiple chemical contaminants. There is particular interest in the loading of anionic nutrients and heavy metals into urban streams, especially those draining to nutrient sensitive receiving waters. However, there has been less characterization of cation chemistry in urban streams. We examined metal concentrations in archived water samples as part of the stream monitoring program of the Baltimore Ecosystem Study (BES), an urban component of the U.S. National Science Foundation Long Term Ecological Research network. Preliminary analysis suggests sewer cross-connections (storm and sanitary) influence metal concentrations (e.g. Si, Ca, Mg). For example, while silica content is elevated in water draining BES agricultural watersheds, it is also elevated in watersheds with extensive impervious surface coverage, areas with the least water-rock interaction. These results raise questions about the effects of urbanization on chemical weathering, the stoichiometry of urban storm and sewer waters, and the potential for human inputs to function as hydrologic tracers in urban watersheds.

Mehta, A. S.; Bain, D. J.; Belt, K. T.; Groffman, P. M.; Kaushal, S. S.; Pouyat, R. V.

2007-12-01

167

Pixel structure for asymmetry removal in ToF 3D camera  

NASA Astrophysics Data System (ADS)

Most of time-of-flight (ToF) cameras have a 2-tap pixel structure for demodulating a reflected near infrared (NIR) from objects. In order to eliminate the asymmetry between two taps in the pixel, a ToF camera needs another measurement, which collects photo-generated electrons from reflected NIR by inverting the phase of clock signals to transfer gates. This asymmetry removal needs additional frame memories and suppresses the frame rate due to the additional timing budget. In this paper, we propose novel asymmetry removal scheme without timing and area overheads by employing 2×2 shared 2-tap pixels with cross-connected transfer gates. The 2-tap pixel is shared with neighbor pixels and transfer gates in the pixel are cross-connected between upper and lower pixels. In order to verify the proposed pixel architecture, an electron charge generated in floating diffusion is simulated. And then we try to calculate a depth from camera to objects using simulated electron charge and measure a linearity of depth. In simulation result, proposed pixel architecture has more linear graph than conventional pixel structure along the real distance of objects.

Kang, Byongmin; Shin, Jungsoon; Choi, Jaehyuk; Kim, James D. K.

2014-03-01

168

Geomagnetic secular variation violating the frozen-flux condition at the core surface  

NASA Astrophysics Data System (ADS)

Possible contributions of the non-advective processes in generating the geomagnetic secular variation (SV) are sought by isolating its parts that are inconsistent with the frozen-flux condition. This condition is known to be derived from the diffusionless radial induction equation and defined explicitly in spatial domain: radial flux changes within a closed null-flux curves at the core surface are not allowed at any instant. We here study this condition in spectral domain, relying on the spherical harmonic expansion of the diffusionless equation, or the observation equation often used in the core suface flow inversion. SV models at a certain epoch are separated into the advective and non-advective parts, each satisfying and not satisfying the frozen-flux condition in spectral domain. The non-uniqueness of the separation is avoided by assuming the orthogonality of the two parts in terms of the radial SV energy at the core-mantle boundary (CMB). From the recent geomagnetic models, GRIMM and CM4, we find that the non-advective part preferentially appear within smaller reverse patches of radial field at the CMB, though it also exhibits more than such a simple configuration as a single signed flux density change within a patch. As long as no restrictions are imposed on the core flow configuration, time variations of the non-advective part are not correlated with those of the original SV models characteristic of the geomagnetic jerks. However, jerks have to be partly non-advective, if the flow is restricted to be tangentially geostrophic. In this limited flow configuration, it is also found that the large part of the secular decrease of the axial dipole does not originate in the advection.

Asari, S.; Lesur, V.; Mandea, M.

2009-04-01

169

Geomagnetic secular variation violating the frozen-flux condition at the core surface  

NASA Astrophysics Data System (ADS)

We consider a method to extract the part of a given geomagnetic secular variation (SV) model that is not consistent with a frozen-flux condition. This condition is usually derived from the diffusionless radial induction equation at the core-mantle boundary (CMB), and is defined explicitly in the spatial domain: radial flux changes within closed null-flux curves at the core surface are not allowed at any instant. We study here this condition in the spherical harmonic (SH) domain, relying on the SH expansion of the diffusionless equation. SV models at a certain epoch are separated into advective and non-advective parts. The advective (resp. non-advective) part satisfies (resp. does not satisfy) the frozen-flux condition redefined in the SH domain. We show that this separation is not unique. In this work, we achieve a unique separation by assuming the orthogonality of the two parts in terms of the radial SV energy at the CMB. From the recent geomagnetic models, GRIMM and CM4, we find that the non-advective part shows up mainly in the small reverse patches of the radial magnetic field at the CMB. However, non-advective behaviors are also observed outside these patches. As far as no restriction is imposed on core flow configuration, time variations of the non-advective part are not correlated to those of the SV models. However, if the flow is restricted to be tangentially geostrophic, time variations of the SV models have to be partly non-advective. Furthermore, for this flow configuration, the secular decrease of the axial dipole has to be largely non-advective.

Asari, S.; Lesur, V.; Mandea, M.

2010-09-01

170

Twitch airway pressure elicited by magnetic phrenic nerve stimulation in anesthetized healthy children.  

PubMed

Children with diaphragm dysfunction may be unable to maintain adequate ventilation. Accurate diagnosis is important, but can only be achieved using an appropriate test and reference range. The aim of this study, therefore, was to measure diaphragm contractility and examine the influence of age and maturation, using magnetic phrenic nerve stimulation in healthy children. Anterolateral magnetic stimulation (MS) of the phrenic nerves was performed using a 43-mm figure-eight coil in 23 children (14 male; mean age, 7.8 years; range, 1.8-15.7) anesthetized for minor surgery with sevoflurane gas. The airway was maintained with a cuffed laryngeal mask airway (LMA) which was briefly occluded during MS. Diaphragm contractility was assessed by measuring the airway pressure (TwPaw) elicited by MS. TwPaw responses were obtained in all subjects, with mean (SD) TwPaw 18.2 (6.8) cm H2O bilateral, 7.3 (3.2) cm H2O left unilateral, and 8.6 (3.1) cm H2O right unilateral. Subgroup analysis was performed in 17 of the children who were prepubertal. Their mean (SD) TwPaw was 17.3 (6.8) cm H2O bilateral, 7.1 (3.7) cm H2O left unilateral, and 8.3 (3.3) right unilateral. The mean (SD) intrapatient coefficients of variation for bilateral and left and right unilateral TwPaw were 8.4% (5.2), 6.7% (3.5), and 11.7% (10.3), respectively. Bilateral and left and right unilateral TwPaw were significantly related to age (P < 0.05). In healthy prepubertal children, diaphragm contractility is primarily influenced by age. PMID:15965896

Rafferty, Gerrard F; Mustfa, Naveed; Man, William D; Sylvester, Karl; Fisher, Antony; Plaza, Miguel; Davenport, Mark; Blaney, Sean; Moxham, John; Greenough, Anne

2005-08-01

171

NASA advanced aeronautics design solar powered remotely piloted vehicle  

NASA Technical Reports Server (NTRS)

Environmental problems such as the depletion of the ozone layer and air pollution demand a change in traditional means of propulsion that is sensitive to the ecology. Solar powered propulsion is a favorable alternative that is both ecologically harmless as well as cost effective. Integration of solar energy into designs ranging from futuristic vehicles to heating is beneficial to society. The design and construction of a Multi-Purpose Remotely Piloted Vehicle (MPRPV) seeks to verify the feasibility of utilizing solar propulsion as a primary fuel source. This task has been a year long effort by a group of ten students, divided into five teams, each dealing with different aspects of the design. The aircraft was designed to take-off, climb to the design altitude, fly in a sustained figure-eight flight path, and cruise for approximately one hour. This mission requires flight at Reynolds numbers between 150,000 and 200,000 and demands special considerations in the aerodynamic design in order to achieve flight in this regime. Optimal performance requires a light weight configuration with both structural integrity and maximum power availability. The structure design and choice of solar cells for the propulsion was governed by the weight, efficiency, and cost considerations. The final design is a MPRPV weighting 35 N which cruises 7 m/s at the design altitude of 50 m. The configuration includes a wing composed of balsa and foam NACA 6409 airfoil sections and carbon fiber spars, a tail of similar construction, and a truss structure fuselage. The propulsion system consists of 98 10 percent efficient solar cells donated by Mobil Solar, a NiCad battery for energy storage, and a folding propeller regulated by a lightweight and efficient control system. The airfoils and propeller chosen for the design were research and tested during the design process.

Elario, David S.; Guillmette, Neal H.; Lind, Gregory S.; Webster, Jonathan D.; Ferreira, Michael J.; Konstantakis, George C.; Marshall, David L.; Windt, Cari L.

1991-01-01

172

Mono- and multi-frequency vortex-induced vibrations of a long tensioned beam in shear flow  

NASA Astrophysics Data System (ADS)

The mono-frequency as well as multi-frequency vortex-induced vibrations of a tensioned beam of aspect ratio 200, immersed in a linear shear flow at Reynolds number 330 and free to move in both the in-line and cross-flow directions, are studied by means of direct numerical simulation. The structural responses are composed of mixed standing-traveling wave patterns. We observe a switch between mono- and multi-frequency vibrations when the mass ratio changes from a value of 3 to 6, while keeping constant the non-dimensional cable and beam phase velocities. This switch is attributed to the accompanying change in the time-averaged in-line curvature of the beam, which alters the oncoming flow velocity component normal to the structure configuration. It is shown, in general, that the mono- or multi-frequency nature of the response is controlled by the form of the profile of the normal component of the oncoming flow.Mono- and multi-frequency vibrations may occur in both the in-line and cross-flow directions, with a frequency ratio close to 2. Each excited frequency is associated with a single structural wavenumber. The local synchronization between the vortex shedding and the cross-flow oscillation, i.e. the lock-in condition, occurs in the high velocity zone and covers a similar spanwise extent in both the mono- and multi-frequency cases. Counter-clockwise figure-eight trajectories are very likely to occur within the lock-in region. In both the mono- and multi-frequency types of response, the flow excites the structural vibrations within the lock-in region and damps the structural motions in the non-lock-in region. The multi-frequency character of the response impacts both the lock-in phenomenon and the fluid-structure energy transfer.

Bourguet, Rémi; Lucor, Didier; Triantafyllou, Michael S.

2012-07-01

173

NASA advanced-aeronautics design solar-powered remotely piloted vehicle  

SciTech Connect

Environmental problems such as the depletion of the ozone layer and air pollution demand a change in traditional means of propulsion that is sensitive to the ecology. Solar powered propulsion is a favorable alternative that is both ecologically harmless as well as cost effective. Integration of solar energy into designs ranging from futuristic vehicles to heating is beneficial to society. The design and construction of a Multi-Purpose Remotely Piloted Vehicle (MPRPV) seeks to verify the feasibility of utilizing solar propulsion as a primary fuel source. This task has been a year long effort by a group of ten students, divided into five teams, each dealing with different aspects of the design. The aircraft was designed to take-off, climb to the design altitude, fly in a sustained figure-eight flight path, and cruise for approximately one hour. This mission requires flight at Reynolds numbers between 150,000 and 200,000 and demands special considerations in the aerodynamic design in order to achieve flight in this regime. Optimal performance requires a light weight configuration with both structural integrity and maximum power availability. The structure design and choice of solar cells for the propulsion was governed by the weight, efficiency, and cost considerations. The final design is a MPRPV weighting 35 N which cruises 7 m/s at the design altitude of 50 m. The configuration includes a wing composed of balsa and foam NACA 6409 airfoil sections and carbon fiber spars, a tail of similar construction, and a truss structure fuselage. The propulsion system consists of 98 10 percent efficient solar cells donated by Mobil Solar, a NiCad battery for energy storage, and a folding propeller regulated by a lightweight and efficient control system. The airfoils and propeller chosen for the design were research and tested during the design process.

Elario, D.S.; Guillmette, N.H.; Lind, G.S.; Webster, J.D.; Ferreira, M.J.; Konstantakis, G.C.; Marshall, D.L.; Windt, C.L.

1991-04-01

174

Hypothesis regarding the transformation of the intended direction of movement during the production of graphic trajectories: a study of drawing movements in 8- to 12-year-old children.  

PubMed

Children from 8 to 12 years of age drew figure-eights and ellipses at a self-chosen tempo on a digitizing tablet. Global aspects (perimeter and average speed) and local aspects (relation between instantaneous speed and curvature) of performance were analyzed across age groups and types of figures. We tested the predictions of the transformation model, which is based on the hypothesis that changing the intended direction of movement is a time-consuming process that affects the evolution in time of the movement trajectory, and compared how well it fitted the data relative to the power law. We found that the relation between speed and curvature was typically better described by the transformation model than by the power law. However, the power law provided a better description when ellipses were drawn at a fast speed. The analyses of the parameters of the transformation model indicate that processing speed increased linearly with age. In addition, the results suggest that the effects of the spring-like properties of the arm were noticeable when ellipses were drawn at a fast speed. This study indicates that both biomechanical properties and central processes have an effect on the kinematics of continuous movements and particularly on the relation between speed and curvature. However, their relative importance varies with the type of figure and average movement speed. In conclusion, the results support the hypothesis that a time-consuming process of transformation of the intended direction of movement is operating during the production of continuous movements and that this process increases in speed between 8 to 12 years of age. PMID:18653177

Pellizzer, Giuseppe; Zesiger, Pascal

2009-03-01

175

Influence of coil current configuration in magnetic stimulation of a nerve fiber in inhomogeneous and anisotropic conducting media.  

PubMed

In this study, we used a computer simulation to investigate the effects of the coil current waveform and direction on the excitation processes of the nerve axon in inhomogeneous and anisotropic conducting media in magnetic stimulation. We assumed that the nerve axon was located in the media with 2 regions having different conductivities or electrical anisotropy that simulate different tissue types. The distribution of induced electric fields was calculated with the finite element method (FEM). The nerve fiber was modeled after equivalent electrical circuits having active nodes of Ranvier. The direction of the coil current at the intersection of a figure-eight coil was assumed to flow perpendicular to the nerve axon. We observed the excitation threshold when the coil current waveform and direction are changed with varying the electrical properties such as tissue electrical conductivity and anisotropy. The simulation results show that the threshold decreases with the increase of conductivity ratio between 2 regions and it also depends on the coil current waveform and direction. Biphasic coil current has lower threshold than monophasic one when the current direction is the same in both waveforms. The results also suggest that the tissue anisotropy strongly affects the excitation threshold. The threshold increases with the increase of tissue anisotropic ratio of longitudinal direction to the transverse one respect to the nerve axon. The results in this study give useful information to explain the experimental results of the magnetic stimulation of human peripheral nervous systems and the theoretical model is applicable to understand the characteristics in magnetic stimulation of both peripheral and central nervous systems. PMID:19964443

Hyodo, Akira; Iramina, Keiji; Ueno, Shoogo

2009-01-01

176

Effects of low-frequency repetitive transcranial magnetic stimulation on event-related potential P300  

NASA Astrophysics Data System (ADS)

The present study analyzed the effects of repetitive transcranial magnetic stimulation (rTMS) on brain activity. P300 latency of event-related potential (ERP) was used to evaluate the effects of low-frequency and short-term rTMS by stimulating the supramarginal gyrus (SMG), which is considered to be the related area of P300 origin. In addition, the prolonged stimulation effects on P300 latency were analyzed after applying rTMS. A figure-eight coil was used to stimulate left-right SMG, and intensity of magnetic stimulation was 80% of motor threshold. A total of 100 magnetic pulses were applied for rTMS. The effects of stimulus frequency at 0.5 or 1 Hz were determined. Following rTMS, an odd-ball task was performed and P300 latency of ERP was measured. The odd-ball task was performed at 5, 10, and 15 min post-rTMS. ERP was measured prior to magnetic stimulation as a control. Electroencephalograph (EEG) was measured at Fz, Cz, and Pz that were indicated by the international 10-20 electrode system. Results demonstrated that different effects on P300 latency occurred between 0.5-1 Hz rTMS. With 1 Hz low-frequency magnetic stimulation to the left SMG, P300 latency decreased. Compared to the control, the latency time difference was approximately 15 ms at Cz. This decrease continued for approximately 10 min post-rTMS. In contrast, 0.5 Hz rTMS resulted in delayed P300 latency. Compared to the control, the latency time difference was approximately 20 ms at Fz, and this delayed effect continued for approximately 15 min post-rTMS. Results demonstrated that P300 latency varied according to rTMS frequency. Furthermore, the duration of the effect was not similar for stimulus frequency of low-frequency rTMS.

Torii, Tetsuya; Sato, Aya; Iwahashi, Masakuni; Iramina, Keiji

2012-04-01

177

Time-dependent effects of low-frequency repetitive transcranial magnetic stimulation of the supramarginal gyrus.  

PubMed

In this paper, we report our studies of the effects of stimulating the bilateral supramarginal gyrus (SMG) with low-frequency transcranial magnetic stimulation (rTMS) or short-term rTMS on brain excitability in humans. We analyzed the effects of various durations of stimulation on P300 latencies of the event-related potential (ERP). Magnetic pulses were delivered using a figure-eight flat coil. The intensity of rTMS was set to 80 % of the subject's motor threshold. In each round of rTMS, 100 magnetic pulses were applied over the scalp at frequencies of 1.00, 0.75, and 0.50 Hz. ERPs were measured prior to magnetic stimulation as a control. The effects of magnetic stimulation were then determined by measuring its effects on P300 latencies elicited by an odd-ball task. These latencies were measured before and 0, 5, 10, and 15 min after the magnetic stimulation. 1.00 Hz low-frequency rTMS of the left SMG decreased P300 latencies for approximately 10 min. In contrast, 0.50 Hz rTMS of the left SMG resulted in delayed P300 latencies for approximately 15 min. We furthermore found that 0.75 Hz rTMS of the left SMG and 1.00, 0.75 and 0.5 Hz rTMS of the right SMG did not affect P300 latencies. These results suggest that the duration of the effects of rTMS depend on the frequency of stimulation. PMID:23366649

Torii, T; Sato, A; Iwahashi, M; Itoh, Y; Iramina, K

2012-01-01

178

Proton-decoupled, Overhauser-enhanced, spatially localized carbon-13 spectroscopy in humans  

SciTech Connect

Spatially localized, natural abundance, carbon (13C) NMR spectroscopy has been combined with proton (1H) decoupling and nuclear Overhauser enhancement to improve 13C sensitivity up to five-fold in the human leg, liver, and heart. Broadhand-decoupled 13C spectra were acquired in 1 s to 17 min with a conventional 1.5-T imaging/spectroscopy system, an auxiliary 1H decoupler, an air-cooled dual-coil coplanar surface probe, and both depth-resolved surface coil spectroscopy (DRESS) and one-dimensional phase-encoding gradient NMR pulse sequences. The surface coil probe comprised circular and figure-eight-shaped coils to eliminate problems with mutual coupling of coils at high decoupling power levels applied during 13C reception. Peak decoupler RF power deposition in tissue was computed numerically from electromagnetic theory assuming a semi-infinite plane of uniform biological conductor. Peak values at the surface were calculated at 4 to 6 W/kg in any gram of tissue for each watt of decoupler power input excluding all coil and cable losses, warning of potential local RF heating problems in these and related experiments. The average power deposition was about 9 mW/kg per watt input, which should present no systemic hazard. At 3 W input, human 13C spectra were decoupled to a depth of about 5 cm while some Overhauser enhancement was sustained up to about 3 cm depth, without ill effect. The observation of glycogen in localized natural abundance 13C spectra of heart and muscle suggests that metabolites in the citric acid cycle should be observable noninvasively using 13C-labeled substrates.

Bottomley, P.A.; Hardy, C.J.; Roemer, P.B.; Mueller, O.M. (GE Corporate Research and Development Center, Schenectady, NY (USA))

1989-12-01

179

Proton-decoupled, Overhauser-enhanced, spatially localized carbon-13 spectroscopy in humans.  

PubMed

Spatially localized, natural abundance, carbon (13C) NMR spectroscopy has been combined with proton (1H) decoupling and nuclear Overhauser enhancement to improve 13C sensitivity up to five-fold in the human leg, liver, and heart. Broadhand-decoupled 13C spectra were acquired in 1 s to 17 min with a conventional 1.5-T imaging/spectroscopy system, an auxiliary 1H decoupler, an air-cooled dual-coil coplanar surface probe, and both depth-resolved surface coil spectroscopy (DRESS) and one-dimensional phase-encoding gradient NMR pulse sequences. The surface coil probe comprised circular and figure-eight-shaped coils to eliminate problems with mutual coupling of coils at high decoupling power levels applied during 13C reception. Peak decoupler RF power deposition in tissue was computed numerically from electromagnetic theory assuming a semi-infinite plane of uniform biological conductor. Peak values at the surface were calculated at 4 to 6 W/kg in any gram of tissue for each watt of decoupler power input excluding all coil and cable losses, warning of potential local RF heating problems in these and related experiments. The average power deposition was about 9 mW/kg per watt input, which should present no systemic hazard. At 3 W input, human 13C spectra were decoupled to a depth of about 5 cm while some Overhauser enhancement was sustained up to about 3 cm depth, without ill effect. The observation of glycogen in localized natural abundance 13C spectra of heart and muscle suggests that metabolites in the citric acid cycle should be observable noninvasively using 13C-labeled substrates. PMID:2560801

Bottomley, P A; Hardy, C J; Roemer, P B; Mueller, O M

1989-12-01

180

Solar powered multipurpose remotely powered aircraft  

NASA Technical Reports Server (NTRS)

Environmental problems such as the depletion of the ozone layer and air pollution demand a change in traditional means of propulsion that is sensitive to the ecology. Solar-powered propulsion is a favorable alternative that is both ecologically harmless as well as cost effective. Integration of solar energy into designs ranging from futuristic vehicles to heating is, therefore, beneficial to society. The design and construction of a Multipurpose Remotely Piloted Vehicle (MPRPV) seeks to verify the feasibility of using solar propulsion as a primary fuel source. This task has been a year-long effort by a group of eight students, divided into four teams, each dealing with different aspects of the design. The aircraft was designed to take off, climb to the design altitude, fly in a sustained figure-eight flight path, and cruise for approximately one hour. This mission requires flight at Reynolds numbers between 150,000 and 200,000 and demands special considerations in the aerodynamic design to achieve flight in this regime. Optimal performance requires a lightweight configuration with both structural integrity and maximum power availability. The structural design and choice of solar cells for the propulsion were governed by weight, efficiency, and cost considerations. The final design is an MPRPV weighing 35 N that cruises at 7 m/s at the design altitude of 50 m. The configuration includes a wing composed of balsa and foam NACA 6409 airfoil sections and carbon fiber spars, a tail of similar construction, and a truss structure fuselage. The propulsion system consists of 98 12.5 percent-efficient solar cells donated by Mobil Solar, a NiCad battery for energy storage, and a folding propeller regulated by a lightweight and efficient control system. The airfoils and propeller chosen for the design were researched and tested during the design process.

1991-01-01

181

Connection error in the delivery of medical gases to a surgical unit.  

PubMed

Whilst anesthetic incidents due to problems with the delivery of medical gases to a surgical unit are exceptional, their consequences are potentially drastic. With the growing of modern hospitals, every anesthetist may one day find himself confronted with such events, which are new to him, partly because they are infrequent, but mainly because they are due to causes outside his immediate environment. A simple mistake in the labelling and identification of medical gas lines resulted in a cross-connection of the oxygen and air, causing perioperative hypoxemia following the administration of a mixture poor in oxygen. The questions of training, responsibility and procedures in regard to these types of incidents are discussed below. PMID:20593642

Dangoisse, M J; Lalot, M; Lechat, J P

2010-01-01

182

Simple optical neighbor discovery (SOND): architecture, applications, and experimental verification  

NASA Astrophysics Data System (ADS)

The architecture, applications, and experimental verification of a simple neighbor discovery method are presented. The method follows the recent International Telecommunication Union - Telecommunication Standardization Sector (ITU-T) and Internet Engineering Task Force (IETF) standardization, automatically switched optical network (ASON)/generalized multiprotocol label switching (GMPLS), on automatically switched optical networks. The method needs no specific hardware components but claims to be so simple that virtually any equipment with common optical ports can support it. It eliminates the need for costly and complex synchronous optical network/synchronous digital hierarchy/optical transport network (SONET/SDH/OTN) overhead read-write functionality in optical elements such as optical cross connects (OXCs). The method thus offers a fast track to automated optical networks.

Larsson, Stefan N.; Hubendick, Sten; Nedelchef, Robert

2003-10-01

183

Ultrafast optical technologies for large-capacity TDM/WDM photonic networks  

NASA Astrophysics Data System (ADS)

As the Internet data traffic increases explosively, the optical networks will evolve into "photonic networks", in which "wavelength" label is used to route large-capacity optical signals at optical path cross connect (OPXCs) nodes. [34] Further development of ultrafast all-optical processing technologies enables us to further upgrade the photonic networks into those with much more flexibility and higher transparency, where ultrafast optical signals of any bit rates (2.5, 10, 40, 100, 160 G/ch) and frame/modulation formats (GbE, 10 GbE, SDH, OTN/ NRZ, RZ, CS-RZ, RZ-DPSK, etc.) are processed and transmitted ail-optically without optical-electrical-optical (O-E-O) conversion from end-to-end.

Morioka, Toshio

184

Peptide immunomodulators versus infection; an analysis.  

PubMed

A disease gets manifested only when the host immune system is not strong enough to fight off the infective agents. A number of small peptides both from natural and synthetic origin are found to be capable of modulating the immune response. While immune adjuvants are known to strengthen the immune response and help the host not to give way to the pathogens thereby preventing their establishment, the immunosuppressors are found useful in autoimmune conditions as well as in facilitating the organ transplants. Recent understanding of immune network, however, reveals its cross connectivity with the endocrine and central nervous systems as well. Thus, the inhibition and control of disease by planned restoration of homeostatis in these systems through immunomodulation is also possible. PMID:12095705

Dutta, Ranjna C

2002-10-01

185

Fbis report. Science and technology: China, October 18, 1995  

SciTech Connect

;Partial Contents: Nanomaterials Fabrication, Applications Research Advances Noted; CAST Announces World`s First Space-Grown Large-Diameter GaAs Monocrystal; Assay of Antiviral Activity of Antisense Phosphorothioate Oligodeoxynucleotide Against Dengue Virus; Expression and Antigenicity of Chimeric Proteins of Cholera Toxin B Subunit With Hepatitis C Virus; CNCOFIEC Signs Agreement With IBM for New Intelligent Building; Latest Reports on Optical Computing, Memory; BIDC To Introduce S3 Company`s Multimedia Accelerator Chipset; Virtual Private PCN Ring Network Based on ATM VP Cross-Connection; Beijing Gets Nation`s First Frame Relay Network; Situation of Power Industry Development and International Cooperation; Diagrams of China`s Nuclear Waste Containment Vessels; Chinese-Developed Containment Vessel Material Reaches World Standards; Second Fuel Elements for Qinshan Plant Passes Inspection; and Geothermal Deep-Well Electric Pump Technology Developed.

NONE

1995-10-18

186

Investigation of improved designs for rotational micromirrors using multiuser MEMS processes  

NASA Astrophysics Data System (ADS)

In recent years, the design of rotational micromirrors for use in optical cross connects has received much attention. Although several companies have already produced and marketed a number of torsional mirror devices, more work is still needed to determine how these mirrors can be integrated into optical systems to form compact optical switches. However, recently several commercial MEMS foundry services have become available. Thus, due to the low cost of these prototyping services, new devices can be fabricated in short amounts of time and the designs adapted to meet the needs of different applications. The purpose of this work is to investigate the fabrication of new micromirror designs using the Multi-User MEMS Processes (MUMPs) foundry service available from Cronos Integrated Microsystems, located in North Carolina (USA). Several sets of mirror designs were submitted for fabrication and the resulting structures characterized using a phase-shifting Mirau interferometer. The results of these devices are presented.

Lin, Julianna E.; Michael, Feras S.; Kirk, Andrew G.

2001-04-01

187

Optimization of Rowland circle mounts for grating demultiplexers and narrow-band spectrographs.  

PubMed

A simple equation for the parameters of the Rowland circle grating mount is derived that ensures that the astigmatism and the meridional spherical aberration are stationary at the wavelength of correction. This is important in optimizing the design of grating multiplexers-demultiplexers and cross connects in wavelengthdivision multiplexed networks and high-resolution narrow-band spectrographs. An analysis of aberrations in three-dimensional and planar two-dimensional optical schemes is presented, and it is shown that in the wavelength range of 1530-1570 nm diffraction-limited performance can be achieved for 160 channels in a three-dimensional multiplexer-demultiplexer and for more than 800 channels for a planar free-space scheme. PMID:19876260

Churin, E G; Bayvel, P; Stavdas, A; Midwinter, J E; Hill, A M

1996-07-15

188

Attack propagation of high-powered intrachannel crosstalk in transparent optical networks  

NASA Astrophysics Data System (ADS)

Transparent optical networks (TON) are becoming increasingly attractive, but transparency introduces security threats, e.g., intrachannel crosstalk attack, to optical networks. In this letter, three attack scenarios, i.e., attack propagation within an optical cross connect (OXC), the secondary attacker traverses successive OXCs and original attacker traverses successive OXCs, are investigated. The scenarios accompanied with gain competition attack are also simulated as comparison. Bit-error-rate (BER), and eye diagram penalties are estimated via VPItransMakerTM. Our work proved that the attack signal will propagate intrachannel crosstalk attack to successive three OXCs but with limited two stages of optical switches in each OXC. The BER will be somewhat higher in case gain competition attack exists. The results will be useful for future managing, planning, and designing on TONs.

Sun, Zeyu; Peng, Yunfeng; Long, Keping

2011-10-01

189

Optical phase transmultiplexing to support traffic grooming in transparent optical networks  

NASA Astrophysics Data System (ADS)

Advanced phase modulation formats, such as differential binary phase-shift keying (DPSK), differential quadrature phase-shift keying (DQPSK), and differential eight-ary phase-shift keying (D8PSK), and so on, have attracted considerable research attention as promising candidates for future optical communication systems. To accommodate different requirements such as nonlinear and dispersion tolerance, implementation complexity or spectral efficiency in different regions of networks, several different modulation formats are expected to coexist in the future optical network. For example, low-speed binary modulation formats may be deployed in the edge networks such as metro or access networks, whereas high-speed or multi-level modulation formats are preferred to be employed at the core networks to support high-speed long-haul transmission. To support the transparent cross-connection among various networks, and the traffic grooming from low-speed edge networks to high-speed core networks, optical phase transmultiplexing technology is highly desirable. In this paper, we report an all-optical phase interleaving technology to phase-multiplex 3x10-Gb/s differential phase-shift keying (DPSK) wavelength-division multiplexing (WDM) signals to a single 30-Gb/s DPSK, and an optical phase-modulated format conversion scheme to convert 2x10-Gb/s DPSK WDM to a single quadrature 20-Gb/s differential quadrature phase-shift keying (DQPSK). The proposed schemes are based on four-wave mixing effect in highly-nonlinear fiber. Different from conventional optical signal processing schemes, the proposed schemes are achieved in optical phase domain directly. Experiments were performed to verify the feasibility of the proposed schemes. Both of them could be applied in transparent optical networks to act as an optical phase transmultiplexer enabling traffic grooming and cross-connection among different networks.

Lu, Guo-Wei

2009-08-01

190

Abdominoplasty and abdominal wall rehabilitation: a comprehensive approach.  

PubMed

Standard abdominoplasty techniques involve a low horizontal or W skin excision, muscle plication, and umbilical transposition. Newer techniques include suction-assisted lipectomy, the use of high lateral tension with fascial suspension, and external oblique muscle advancement. The author has modified these traditional procedures and added new techniques to improve the aesthetic and functional results of the abdominoplasty procedure. This modification provides a comprehensive approach to abdominal wall aesthetic improvement and rehabilitation. The comprehensive approach described includes four components: the "U-M dermolipectomy," "V umbilicoplasty," the rectus abdominis "myofascial release," and suction-assisted lipectomy. The patient is marked while standing for areas of suction lipectomy and undermining. The lower incision is designed as an open U with the lateral limbs placed inside the bikini line. The upper incision is a lazy M with the higher peaks located at the level of the flanks. Subcutaneous hydration is achieved to perform suction along the flanks, waistline, and iliac areas. Gentle suction of the flaps is also performed. The umbilicus is cored out in a heart shape. The flaps within the U-M marks are excised, and the undermining is performed to the xiphoid and costal margins. The rectus diastasis is marked, and the anterior rectus fascia is incised at the junction of the medial third with the central third of the width of the rectus sheath. Horizontal figure-eight plication sutures by using the lateral fascial edge enable easier infolding of the central tissue. The new recipient of the umbilicus is made by an incision in a V shape on the abdominal flap. The umbilicus is telescoped, and the triangular flap of the abdomen is sutured to the triangular defect of the umbilicus. Skin flap fixation to the umbilicus relieves tension in the lower portion of the flap. The upper skin flap, which is cut in an M manner, provides lateral tension and matches the length of the lower flap. A standard fascial suspension is used and closure is performed in layers. The techniques described here are intertwined procedures. Each facilitates the accomplishment of the other procedure, and they complement each other. They all attain the 12 objectives of the abdominoplasty described. These combined techniques have been used in 104 patients in a period of 11 years. Complications were minimal and easily manageable, except for one patient who required excision of a pseudobursa and retightening of the lower quadrants of the abdominal wall musculature to correct extreme lordosis. A comprehensive approach for the treatment of complex abdominal wall aesthetic and functional defects is presented. These require thoughtful integration of the four components mentioned. This approach has allowed predictable, reproducible, and aesthetically pleasing results. PMID:10627012

Ramirez, O M

2000-01-01

191

Modulation of amplitude and latency of motor evoked potential by direction of transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

The present study analyzed the effects of monophasic magnetic stimulation to the motor cortex. The effects of magnetic stimulation were evaluated by analyzing the motor evoked potentials (MEPs). The amplitude and latency of MEPs on the abductor pollicis brevis muscle were used to evaluate the effects of repetitive magnetic stimulation. A figure eight-shaped flat coil was used to stimulate the region over the primary motor cortex. The intensity of magnetic stimulation was 120% of the resting motor threshold, and the frequency of magnetic stimulation was 0.1 Hz. In addition, the direction of the current in the brain was posterior-anterior (PA) or anterior-posterior (AP). The latency of MEP was compared with PA and AP on initial magnetic stimulation. The results demonstrated that a stimulus in the AP direction increased the latency of the MEP by approximately 2.5 ms. MEP amplitude was also compared with PA and AP during 60 magnetic stimulations. The results showed that a stimulus in the PA direction gradually increased the amplitude of the MEP. However, a stimulus in the AP direction did not modulate the MEP amplitude. The average MEP amplitude induced from every 10 magnetic pulses was normalized by the average amplitude of the first 10 stimuli. These results demonstrated that the normalized MEP amplitude increased up to approximately 150%. In terms of pyramidal neuron indirect waves (I waves), magnetic stimulation inducing current flowing backward to the anterior preferentially elicited an I1 wave, and current flowing forward to the posterior elicited an I3 wave. It has been reported that the latency of the I3 wave is approximately 2.5 ms longer than the I1 wave elicitation, so the resulting difference in latency may be caused by this phenomenon. It has also been reported that there is no alteration of MEP amplitude at a frequency of 0.1 Hz. However, this study suggested that the modulation of MEP amplitude depends on stimulation strength and stimulation direction.

Sato, Aya; Torii, Tetsuya; Iwahashi, Masakuni; Itoh, Yuji; Iramina, Keiji

2014-05-01

192

Adaptive Morphological Feature-Based Object Classifier for a Color Imaging System  

NASA Technical Reports Server (NTRS)

Utilizing a Compact Color Microscope Imaging System (CCMIS), a unique algorithm has been developed that combines human intelligence along with machine vision techniques to produce an autonomous microscope tool for biomedical, industrial, and space applications. This technique is based on an adaptive, morphological, feature-based mapping function comprising 24 mutually inclusive feature metrics that are used to determine the metrics for complex cell/objects derived from color image analysis. Some of the features include: Area (total numbers of non-background pixels inside and including the perimeter), Bounding Box (smallest rectangle that bounds and object), centerX (x-coordinate of intensity-weighted, center-of-mass of an entire object or multi-object blob), centerY (y-coordinate of intensity-weighted, center-of-mass, of an entire object or multi-object blob), Circumference (a measure of circumference that takes into account whether neighboring pixels are diagonal, which is a longer distance than horizontally or vertically joined pixels), . Elongation (measure of particle elongation given as a number between 0 and 1. If equal to 1, the particle bounding box is square. As the elongation decreases from 1, the particle becomes more elongated), . Ext_vector (extremal vector), . Major Axis (the length of a major axis of a smallest ellipse encompassing an object), . Minor Axis (the length of a minor axis of a smallest ellipse encompassing an object), . Partial (indicates if the particle extends beyond the field of view), . Perimeter Points (points that make up a particle perimeter), . Roundness [(4(pi) x area)/perimeter(squared)) the result is a measure of object roundness, or compactness, given as a value between 0 and 1. The greater the ratio, the rounder the object.], . Thin in center (determines if an object becomes thin in the center, (figure-eight-shaped), . Theta (orientation of the major axis), . Smoothness and color metrics for each component (red, green, blue) the minimum, maximum, average, and standard deviation within the particle are tracked. These metrics can be used for autonomous analysis of color images from a microscope, video camera, or digital, still image. It can also automatically identify tumor morphology of stained images and has been used to detect stained cell phenomena (see figure).

McDowell, Mark; Gray, Elizabeth

2009-01-01

193

Campers' diarrhea outbreak traced to water-sewage link.  

PubMed Central

From June through September 1979, diarrheal illness occurred in an estimated 1,850 persons who had camped at a private campground in Arizona. Illness occurred more frequently among campers at that campground than among those in the adjacent State park (P less than 0.0001). The same well served both the private and the State campgrounds as the source of drinking water, but that water was distributed to the two campgrounds through separate lines. Illness was significantly associated with drinking water at the campsite (P less than 0.0001), drinking larger quantities of campsite water (P less than 0.001), and camping on the southwest side of the campground (P less than 0.001). Samples of the water collected from the system during January through June contained no coliform bacteria. However, all those samples had been collected from the State park only. Of the 11 water samples submitted for bacteriological analyses during the summer, 3 had high levels of bacteria. Excavation of the water system uncovered a direct cross connection between the potable water system and a sewage-effluent irrigation system. This outbreak calls attention to the importance of designing, maintaining, and monitoring potable water systems properly, especially those proximate to wastewater re-use systems.

Starko, K M; Lippy, E C; Dominguez, L B; Haley, C E; Fisher, H J

1986-01-01

194

Death and Transfiguration in Static Staphylococcus epidermidis Cultures.  

PubMed

The overwhelming majority of bacteria live in slime embedded microbial communities termed biofilms, which are typically adherent to a surface. However, when several Staphylococcus epidermidis strains were cultivated in static liquid cultures, macroscopic aggregates were seen floating within the broth and also sedimented at the test tube bottom. Light- and electron microscopy revealed that early-stage aggregates consisted of bacteria and extracellular matrix, organized in sheet-like structures. Perpendicular under the sheets hung a network of periodically arranged, bacteria-associated strands. During the extended cultivation, the strands of a subpopulation of aggregates developed into cross-connected wall-like structures, in which aligned bacteria formed the walls. The resulting architecture had a compartmentalized appearance. In late-stage cultures, the wall-associated bacteria disintegrated so that, henceforth, the walls were made of the coalescing remnants of lysed bacteria, while the compartment-like organization remained intact. At the same time, the majority of strand-containing aggregates with associated culturable bacteria continued to exist. These observations indicate that some strains of Staphylococcus epidermidis are able to build highly sophisticated structures, in which a subpopulation undergoes cell lysis, presumably to provide continued access to nutrients in a nutrient-limited environment, whilst maintaining structural integrity. PMID:24964210

Schaudinn, Christoph; Stoodley, Paul; Hall-Stoodley, Luanne; Gorur, Amita; Remis, Jonathan; Wu, Siva; Auer, Manfred; Hertwig, Stefan; Guerrero-Given, Debbie; Hu, Fen Ze; Ehrlich, Garth D; Costerton, John William; Robinson, Douglas H; Webster, Paul

2014-01-01

195

Urban wet-weather flows: sources of fecal contamination impacting on recreational waters and threatening drinking-water sources.  

PubMed

Discharges of urban stormwater and combined sewer overflows (CSOs) contribute to fecal contamination of urban waters and need to be considered in planning the protection of recreational waters and sources of drinking water. Stormwater characterization indicates that Escherichia coli counts in stormwater typically range from 103 to 104 units per 100 ml. Higher counts (10(5) units/100 ml) suggest the presence of cross-connections with sanitary sewers, and such connections should be identified and corrected. Fecal contamination of stormwater may be attenuated prior to discharge into surface waters by stormwater management measures, which typically remove suspended solids and attached bacteria. Exceptionally, stormwater discharges in the vicinity of swimming beaches are disinfected. The levels of indicator bacteria in CSOs can be as high as 10(6) E. coli per 100 ml. Consequently, the abatement of fecal contamination of CSOs is now considered in the design of CSO control and treatment, as for example stipulated in the Ontario Procedure F-5-5. CSO abatement options comprise combin ations of storage and treatment, in which the CSO treatment generally includes disinfection by ultraviolet (UV) irradiation. Finally, indicator bacteria data from Sarnia (Ontario) were used to demonstrate some fecal contamination impacts of wet-weather flows. In wet weather, the microbiological quality of riverine water worsened as a result of CSO and stormwater discharges, and the recreational water guidelines for indicator organisms were exceeded most of the time. Local improvements in water quality were feasible by source controls and diversion of polluted water. PMID:15371215

Marsalek, Jiri; Rochfort, Quintin

196

Evaluation of novel resilience schemes in dynamic optical transport networks  

NASA Astrophysics Data System (ADS)

Today, Wavelength Division Multiplexing (WDM) transmission systems are deployed extensively in transport networks. They are used mainly for static point-to-point connections. With the availability of fast reconfigurable Optical Cross Connects (OXC) and the introduction of a control plane in the Optical Transport Network (OTN), optical channel based logical networks can be built for dynamic WDM networks. Resilience in current transport networks is mainly based on static SONET/SDH dedicated and shared protection. Distributed control planes allow new, flexible protection mechanisms (e.g. GMPLS reroute and fast reroute). To evaluate future distributed control concepts and new resilience schemes in transport networks, we have implemented a dynamic OTN simulation model. Several case studies have been performed using different protection and restoration methods. Different failure scenarios (single or multiple link failures) were used. The paper evaluates the case studies in terms of scalability, recovery time criteria, capacity use (efficiency) and availability. It is shown that the new and flexible resilience schemes are a promising alternative to traditional statically preplanned protection in transport networks. Furthermore, they provide increased network availability in multiple failure cases.

Jaeger, Monika; Huelsermann, Ralf; Schupke, Dominic A.; Sedlak, Rene

2002-09-01

197

Light emission from silicon: Some perspectives and applications  

NASA Astrophysics Data System (ADS)

Research on efficient light emission from silicon devices is moving toward leading-edge advances in components for nano-optoelectronics and related areas. A silicon laser is being eagerly sought and may be at hand soon. A key advantage is in the use of silicon-based materials and processing, thereby using high yield and low-cost fabrication techniques. Anticipated applications include an optical emitter for integrated optical circuits, logic, memory, and interconnects; electro-optic isolators; massively parallel optical interconnects and cross connects for integrated circuit chips; lightwave components; high-power discrete and array emitters; and optoelectronic nanocell arrays for detecting biological and chemical agents. The new technical approaches resolve a basic issue with native interband electro-optical emission from bulk Si, which competes with nonradiative phonon- and defect-mediated pathways for electron-hole recombination. Some of the new ways to enhance optical emission efficiency in Si diode devices rely on carrier confinement, including defect and strain engineering in the bulk material. Others use Si nanocrystallites, nanowires, and alloying with Ge and crystal strain methods to achieve the carrier confinement required to boost radiative recombination efficiency. Another approach draws on the considerable progress that has been made in high-efficiency, solar-cell design and uses the reciprocity between photo- and light-emitting diodes. Important advances are also being made with silicon-oxide materials containing optically active rare-earth impurities.

Fiory, A. T.; Ravindra, N. M.

2003-10-01

198

AOSC multichannel electronic variable optical attenuator  

NASA Astrophysics Data System (ADS)

Optical networks are becoming a reality as the physical layer of high-performance telecommunication networks. The deployment of wavelength-division multiplexing (WDM) technology allows the extended exploitation of installed fibers now facing an increasing traffic capacity demand. Performances of such systems can be degraded by wide variations of the optical channel power following propagation in the network. Therefore a tilt control of optical amplifiers in WDM networks and dynamic channel power regulation and equalisation in cross-connected nodes is necessary. An important tool for the system designer is the variable optical attenuator (VOA). We present the design and the realization of newly developed VOAs using the ASOC technology. This technology refers to the fabrication of integrated optics components in silicon-on-insulator (SOI) material. The device is based on the light absorption by the free-carriers that are injected in the core of a rib waveguide from a p-i-n diode. The devices incorporate horizontally and vertically tapered waveguides for minimum fiber coupling loss. The p-i-n diode for carrier injection into the active region of the rib waveguide was optimised in order to enhance the attenuation. One major advantage of the ASOC technology is the possibility of monolithic integration of many integrated optics devices on one chip. In the light of this the paper illustrates the result of characterisation of multichannel VOAs.

Vonsovici, Adrian; Day, Ian E.; House, Andrew A.; Asghari, Mehdi

2001-05-01

199

Smart repeater system for communications interoperability during multiagency law enforcement operations  

NASA Astrophysics Data System (ADS)

A prototype 'smart' repeater that provides interoperability capabilities for radio communication systems in multi-agency and multi-user scenarios is being developed by the Oak Ridge National Laboratory. The smart repeater functions as a deployable communications platform that can be dynamically reconfigured to cross-link the radios of participating federal, state, and local government agencies. This interconnection capability improves the coordination and execution of multi-agency operations, including coordinated law enforcement activities and general emergency or disaster response scenarios. The repeater provides multiple channels of operation in the 30-50, 118-136, 138-174, and 403-512 MHz land mobile communications and aircraft bands while providing the ability to cross-connect among multiple frequencies, bands, modulation types, and encryption formats. Additionally, two telephone interconnects provide links to the fixed and cellular telephone networks. The 800- and 900-MHz bands are not supported by the prototype, but the modular design of the system accommodates future retrofits to extend frequency capabilities with minimal impact to the system. Configuration of the repeater is through a portable personal computer with a Windows-based graphical interface control screen that provides dynamic reconfiguration of network interconnections and formats.

Crutcher, Richard I.; Jones, R. W.; Moore, Michael R.; Smith, S. F.; Tolley, Alan L.; Rochelle, Robert W.

1997-02-01

200

Regularity-based functional streamflow disaggregation: 1. Comprehensive foundation  

NASA Astrophysics Data System (ADS)

An integrated, largely nonprobabilistic, calibration-free approach is proposed to identify, estimate, evaluate, and attribute conceptual components of a streamflow time series. We assess its gross functional aggregation from the signal structure alone by consistently exploiting elementary constraints. Starting from the separability concept of linear operator theory, cross connections are revealed of such a blind functional streamflow disaggregation to qualitative dynamics. The algorithm is initialized by a first guess of regular behavior using singular-system analysis (SSA). To approach the regular/singular borderline of the data and to separate a fast flow from total runoff, this (probabilistic) SSA mode is transformed into a lower envelope to the series via iterative cubic spline interpolation (CSI). Repeated CSI yields a hierarchy of lower envelopes that piles up part of a transient component and converges into a slow one. A lower bound is constructed as an instantaneous low flow using the leading SSA eigenvector. We demonstrate the method for highlands river stations, compare its results with those from distributed hydrologic models, and discuss attributions to overland flow, interflow, and base flow. For independent evaluation we resort to singularity-based multifractal analyses.

Carl, P.; Behrendt, H.

2008-02-01

201

Real-time monitoring of river water quality using in-line continuous acquisition of fluorescence excitation and emission matrices  

NASA Astrophysics Data System (ADS)

In-line fluorescence EEM monitoring has been performed over an eleven-day period for Bournbrook River, Birmingham, UK. River water was diverted to a portable laboratory via a continuous flow pump and filter system. Fluorescence excitation-emission matrices data was recorded every 3 minutes using a flow cell (1cm pathlength) coupled to a fiber optic probe. This real-time fluorescence EEM data (Excitation, 225-400 nm at 5 nm steps, emission, 280-500 nm at 2 nm steps) was collected 'in-line'and directly compared with the spectrophotometric properties and physical and chemical parameters of river water samples collected off-line at known time intervals. Over the monitoring period, minor pollution pulses from cross connections were detected and identified hourly along with a random diesel pollution event. This work addresses the practicalities of measuring and detecting fluorescence EEM in the field and discusses the potential of this technological approach for further understanding important hydrological and biogeochemical processes. Problems associated with fouling and system failure are also reported. Example of the data generated from the continuous fluorescence EEM monitoring.

Carstea, E.; Baker, A.; Johnson, R.; Reynolds, D. M.

2009-12-01

202

Supporting differentiated quality of service in optical burst switched networks  

NASA Astrophysics Data System (ADS)

We propose and evaluate two new schemes for providing differentiated services in optical burst switched (OBS) networks. The two new schemes are suitable for implementation in OBS networks using just-in-time (JIT) or just-enough-time (JET) scheduling protocols. The first scheme adjusts the size of the search space for a free wavelength based on the priority level of the burst. A simple equation is used to divide the search spectrum into two parts: a base part and an adjustable part. The size of the adjustable part increases as the priority of the burst becomes higher. The scheme is very easy to implement and does not demand any major software or hardware resources in optical cross-connects. The second scheme reduces the dropping probability of bursts with higher priorities through the use of different proactive discarding rates in the network access station (NAS) of the source node. Our extensive simulation tests using JIT show that both schemes are capable of providing tangible quality of service (QoS) differentiation without negatively impacting the throughput of OBS networks.

Zhou, Bin; Bassiouni, Mostafa A.

2006-01-01

203

Geochemical heterogeneity in a small, stratigraphically complex moraine aquifer system (Ontario, Canada): Interpretation of flow and recharge using multiple geochemical parameters  

USGS Publications Warehouse

The Waterloo Moraine is a stratigraphically complex system and is the major water supply to the cities of Kitchener and Waterloo in Ontario, Canada. Despite over 30 years of investigation, no attempt has been made to unify existing geochemical data into a single database. A composite view of the moraine geochemistry has been created using the available geochemical information, and a framework created for geochemical data synthesis of other similar flow systems. Regionally, fluid chemistry is highly heterogeneous, with large variations in both water type and total dissolved solids content. Locally, upper aquifer units are affected by nitrate and chloride from fertilizer and road salt. Typical upper-aquifer fluid chemistry is dominated by calcium, magnesium, and bicarbonate, a result of calcite and dolomite dissolution. Evidence also suggests that ion exchange and diffusion from tills and bedrock units accounts for some elevated sodium concentrations. Locally, hydraulic "windows" cross connect upper and lower aquifer units, which are typically separated by a clay till. Lower aquifer units are also affected by dedolomitization, mixing with bedrock water, and locally, upward diffusion of solutes from the bedrock aquifers. A map of areas where aquifer units are geochemically similar was constructed to highlight areas with potential hydraulic windows. ?? 2010 Springer-Verlag.

Stotler, R. L.; Frape, S. K.; El, Mugammar, H. T.; Johnston, C.; Judd-Henrey, I.; Harvey, F. E.; Drimmie, R.; Jones, J. P.

2011-01-01

204

Water security: the importance of designing dual use into solutions  

NASA Astrophysics Data System (ADS)

Water infrastructure needs in the US are expected to exceed a cost of over 300 billion dollars in the coming years. While security has become a priority since 9/11 budgets for this expenditure are often constrained. This necessitates that solutions be dual use in nature. Since 9/11 numerous communities have installed multi-parameter monitoring stations in the distribution system as early warning systems for potential water security threats. These systems have recorded large streams of data relevant to water quality in the distribution systems. In this study data streams from a number of communities are analyzed for pertinent information as to the health and operation of the distribution system. Changes in water quality are correlated with known causes attributable to day-to-day operational changes and also anomalous events (pipe bursts, accidental back flows, cross connections, chemical over feeds, treatment plant problems, nitrification events, etc.). Information concerning what action was taken to ameliorate the problem will also be linked to the data for the identified events thus demonstrating dual use for these systems.

Kroll, Dan

2009-05-01

205

Smart repeater system for communications interoperability during multi-agency law enforcement operations  

SciTech Connect

A prototype smart repeater that provides interoperability capabilities for radio communication systems in multi-agency and multi-user scenarios is being developed by the Oak Ridge National Laboratory. The smart repeater functions as a deployable communications platform that can be dynamically reconfigured to cross-link the radios of participating federal, state, and local government agencies. This interconnection capability improves the coordination and execution of multi-agency operations, including coordinated law enforcement activities and general emergency or disaster response scenarios. The repeater provides multiple channels of operation in the 30--50, 118--136, 138--174, and 403--512 MHz land mobile communications and aircraft bands while providing the ability to cross-connect among multiple frequencies, bands, modulation types, and encryption formats. Additionally, two telephone interconnects provide links to the fixed and cellular telephone networks. The 800- and 900-MHz bands are not supported by the prototype, but the modular design of the system accommodates future retrofits to extend frequency capabilities with minimal impact to the system. Configuration of the repeater is through a portable personal computer with a Windows-based graphical interface control screen that provides dynamic reconfiguration of network interconnections and formats.

Crutcher, R.I.; Jones, R.W.; Moore, M.R.; Smith, S.F.; Tolley, A.L. [Oak Ridge National Lab., TN (United States); Rochelle, R.W. [Univ. of Tennessee, Knoxville, TN (United States). Electrical Engineering Dept.

1996-12-31

206

Broadband access development  

NASA Astrophysics Data System (ADS)

In upgrading the access network to be broadband capable, re- use of existing infrastructure is essential to manage the risk associated with this development. FTTCab (fiber to the cabinet) has been proposed as an architecture that can make this development economic to provide 12 Mbit/s to the customer and 2 Mbit/s back into the network. The FTTCab architecture uses an optical fiber overlay to an active node sited at the primary cross-connect point (PCP) in the copper access network. Frequency multiplexing allows the copper pair infrastructure to be re-used without changing the existing narrowband services. FTTCab is at the mid-point of a range of access topologies with respect to the siting of the DSL (digital subscriber loop) technology. The DSL modem can be sited at the home, curb, cabinet, or in the exchange to suit a range of distance/capacity requirements. This enables a simple revolution of the current network to FTTCab, and allows the architecture to be flexed to satisfy particular business needs.

Quayle, Alan; Faulkner, David W.

1996-11-01

207

An Experiment of GMPLS-Based Dispersion Compensation Control over In-Field Fibers  

NASA Astrophysics Data System (ADS)

As ROADMs (Reconfigurable Optical Add/Drop Multiplexers) are becoming widely used in metro/core networks, distributed control of wavelength paths by extended GMPLS (Generalized MultiProtocol Label Switching) protocols has attracted much attention. For the automatic establishment of an arbitrary wavelength path satisfying dynamic traffic demands over a ROADM or WXC (Wavelength Cross Connect)-based network, precise determination of chromatic dispersion over the path and optimized assignment of dispersion compensation capabilities at related nodes are essential. This paper reports an experiment over in-field fibers where GMPLS-based control was applied for the automatic discovery of chromatic dispersion, path computation, and wavelength path establishment with dynamic adjustment of variable dispersion compensation. The GMPLS-based control scheme, which the authors called GMPLS-Plus, extended GMPLS's distributed control architecture with attributes for automatic discovery, advertisement, and signaling of chromatic dispersion. In this experiment, wavelength paths with distances of 24km and 360km were successfully established and error-free data transmission was verified. The experiment also confirmed path restoration with dynamic compensation adjustment upon fiber failure.

Seno, Shoichiro; Horiuchi, Eiichi; Yoshida, Sota; Sugihara, Takashi; Onohara, Kiyoshi; Kamei, Misato; Baba, Yoshimasa; Kubo, Kazuo; Mizuochi, Takashi

208

Optonanomechanical self-adaptive photonic devices based on light forces: a path to robust high-index-contrast nanophotonic circuits  

NASA Astrophysics Data System (ADS)

We describe a proposed new class of optonanomechanical integrated photonic devices that can have self-adaptive behavior and self-adaptive optical frequency response, through the use of optical forces to manipulate their movable parts. We propose applications for this technology, and show how such devices can address the enormous dimensional and thermal sensitivity present in nanophotonic structures. Through synthesis of the optomechanical potential, we propose to design and control either the effective optical, or the mechanical, properties of the nanostructure, such as a giant effective optical nonlinear response, nonlinear dynamics and memory. We show device designs that can trap desired states at picometer resolution. We also describe the design of a novel, self-tuning microcavity design whose moving parts adjust in response to light forces alone to always place the resonance at the wavelength of the incident light over a wide wavelength range. This device concept provides an athermal resonator design (temperature-independent resonance frequency), without use of materials with negative thermooptic coefficients. It could also address a major challenge with conventional strong-confinement (high-index-contrast) integrated photonics - their extreme sensitivities - through a self-locking filter bank and optical cross-connect proposal, that in principle can use arbitrarily low power to trim resonant filter passbands to a wavelength channel grid.

Popovic, Milos A.; Rakich, Peter T.

2009-02-01

209

Death and Transfiguration in Static Staphylococcus epidermidis Cultures  

PubMed Central

The overwhelming majority of bacteria live in slime embedded microbial communities termed biofilms, which are typically adherent to a surface. However, when several Staphylococcus epidermidis strains were cultivated in static liquid cultures, macroscopic aggregates were seen floating within the broth and also sedimented at the test tube bottom. Light- and electron microscopy revealed that early-stage aggregates consisted of bacteria and extracellular matrix, organized in sheet-like structures. Perpendicular under the sheets hung a network of periodically arranged, bacteria-associated strands. During the extended cultivation, the strands of a subpopulation of aggregates developed into cross-connected wall-like structures, in which aligned bacteria formed the walls. The resulting architecture had a compartmentalized appearance. In late-stage cultures, the wall-associated bacteria disintegrated so that, henceforth, the walls were made of the coalescing remnants of lysed bacteria, while the compartment-like organization remained intact. At the same time, the majority of strand-containing aggregates with associated culturable bacteria continued to exist. These observations indicate that some strains of Staphylococcus epidermidis are able to build highly sophisticated structures, in which a subpopulation undergoes cell lysis, presumably to provide continued access to nutrients in a nutrient-limited environment, whilst maintaining structural integrity.

Schaudinn, Christoph; Stoodley, Paul; Hall-Stoodley, Luanne; Gorur, Amita; Remis, Jonathan; Wu, Siva; Auer, Manfred; Hertwig, Stefan; Guerrero-Given, Debbie; Hu, Fen Ze; Ehrlich, Garth D.; Costerton, John William; Robinson, Douglas H.; Webster, Paul

2014-01-01

210

Hydraulic testing using a versatile straddle packer system for improved transmissivity estimation in fractured-rock boreholes  

NASA Astrophysics Data System (ADS)

Equipment has been developed for straddle packer testing in fractured-rock boreholes to conduct four types of tests (constant-head step tests, slug tests, constant-rate pumping tests, and recovery tests) without deflating the packers or adjusting equipment in the hole between tests. The goal is to achieve improved accuracy and precision in the determination of transmissivity ( T). Water-pressure measurements are recorded using pressure transducers positioned above and below the test interval to identify connections from the test interval to the open borehole. Insights concerning the nature of test conditions are gathered with this equipment to assess errors related to deviations from assumptions inherent in the mathematical models used to determine T, including validation of the Darcian flow assumption, validation of slug test assumptions, cross-connection to the open borehole, inadequate borehole development, and dual permeability, thereby giving greater confidence in the calculated T values. When the errors indicated above are minimized, the constant-head step tests, slug tests and constant-rate pumping/recovery tests give nearly identical values. This multiple-test approach to fractured-rock studies increases confidence in test results, which is important when the goal is characterization of fracture networks for contaminant transport and fate assessment.

Quinn, Patryk; Cherry, John A.; Parker, Beth L.

2012-12-01

211

Disorganization of Equilibrium Directional Interactions in the Brain Motor Network of Parkinson's disease: New Insight of Resting State Analysis Using Granger Causality and Graphical Approach  

PubMed Central

Parkinson's disease (PD) is a progressive neurological disorder characterized by tremor, rigidity, and slowness of movements. Particular changes related to various pathological attacks in PD could result in causal interactions of the brain network from resting state functional magnetic resonance imaging (rs-fMRI) data. In this paper, we aimed to disclose the network structure of the directed influences over the brain using multivariate Granger causality analysis and graph theory in patients with PD as compared with control group. rs-fMRI at rest from 10 PD patients and 10 controls were analyzed. Topological properties of the networks showed that information flow in PD is smaller than that in healthy individuals. We found that there is a balanced local network in healthy control group, including positive pair-wise cross connections between caudate and cerebellum and reciprocal connections between motor cortex and caudate in the left and right hemispheres. The results showed that this local network is disrupted in PD due to disturbance of the interactions in the motor networks. These findings suggested alteration of the functional organization of the brain in the resting state that affects the information transmission from and to other brain regions related to both primary dysfunctions and higher-level cognition impairments in PD. Furthermore, we showed that regions with high degree values could be detected as betweenness centrality nodes. Our results demonstrate that properties of small-world connectivity could also recognize and quantify the characteristics of directed influence brain networks in PD.

Ghasemi, Mahdieh; Mahloojifar, Ali

2013-01-01

212

Geochemical heterogeneity in a small, stratigraphically complex moraine aquifer system (Ontario, Canada): interpretation of flow and recharge using multiple geochemical parameters  

NASA Astrophysics Data System (ADS)

The Waterloo Moraine is a stratigraphically complex system and is the major water supply to the cities of Kitchener and Waterloo in Ontario, Canada. Despite over 30 years of investigation, no attempt has been made to unify existing geochemical data into a single database. A composite view of the moraine geochemistry has been created using the available geochemical information, and a framework created for geochemical data synthesis of other similar flow systems. Regionally, fluid chemistry is highly heterogeneous, with large variations in both water type and total dissolved solids content. Locally, upper aquifer units are affected by nitrate and chloride from fertilizer and road salt. Typical upper-aquifer fluid chemistry is dominated by calcium, magnesium, and bicarbonate, a result of calcite and dolomite dissolution. Evidence also suggests that ion exchange and diffusion from tills and bedrock units accounts for some elevated sodium concentrations. Locally, hydraulic "windows" cross connect upper and lower aquifer units, which are typically separated by a clay till. Lower aquifer units are also affected by dedolomitization, mixing with bedrock water, and locally, upward diffusion of solutes from the bedrock aquifers. A map of areas where aquifer units are geochemically similar was constructed to highlight areas with potential hydraulic windows.

Stotler, Randy L.; Frape, Shaun K.; El Mugammar, Humam Taha; Johnston, Craig; Judd-Henrey, Ian; Harvey, F. Edwin; Drimmie, Robert; Jones, Jon Paul

2011-02-01

213

Managing risks from virus intrusion into water distribution systems due to pressure transients.  

PubMed

Low or negative pressure transients in water distribution systems, caused by unexpected events (e.g. power outages) or routine operation/maintenance activities, are usually brief and thus are rarely monitored or alarmed. Previous studies have shown connections between negative pressure events in water distribution systems and potential public health consequences. Using a quantitative microbial risk assessment (QMRA) model previously developed, various factors driving the risk of viral infection from intrusion were evaluated, including virus concentrations external to the distribution system, maintenance of a disinfectant residual, leak orifice sizes, the duration and the number of nodes drawing negative pressures. The most sensitive factors were the duration and the number of nodes drawing negative pressures, indicating that mitigation practices should be targeted to alleviate the severity of low/negative pressure transients. Maintaining a free chlorine residual of 0.2 mg/L or above is the last defense against the risk of viral infection due to negative pressure transients. Maintaining a chloramine residual did not appear to significantly reduce the risk. The effectiveness of ensuring separation distances from sewer mains to reduce the risk of infection may be system-specific. Leak detection/repair and cross-connection control should be prioritized in areas vulnerable to negative pressure transients. PMID:21942194

Yang, Jian; LeChevallier, Mark W; Teunis, Peter F M; Xu, Minhua

2011-06-01

214

"Stop Ne(c)king around": How interactomics contributes to functionally characterize Nek family kinases  

PubMed Central

Aside from Polo and Aurora, a third but less studied kinase family involved in mitosis regulation is the never in mitosis-gene A (NIMA)-related kinases (Neks). The founding member of this family is the sole member NIMA of Aspergillus nidulans, which is crucial for the initiation of mitosis in that organism. All 11 human Neks have been functionally assigned to one of the three core functions established for this family in mammals: (1) centrioles/mitosis; (2) primary ciliary function/ciliopathies; and (3) DNA damage response (DDR). Recent findings, especially on Nek 1 and 8, showed however, that several Neks participate in parallel in at least two of these contexts: primary ciliary function and DDR. In the core section of this in-depth review, we report the current detailed functional knowledge on each of the 11 Neks. In the discussion, we return to the cross-connections among Neks and point out how our and other groups’ functional and interactomics studies revealed that most Neks interact with protein partners associated with two if not all three of the functional contexts. We then raise the hypothesis that Neks may be the connecting regulatory elements that allow the cell to fine tune and synchronize the cellular events associated with these three core functions. The new and exciting findings on the Nek family open new perspectives and should allow the Neks to finally claim the attention they deserve in the field of kinases and cell cycle biology.

Meirelles, Gabriela Vaz; Perez, Arina Marina; de Souza, Edmarcia Elisa; Basei, Fernanda Luisa; Papa, Priscila Ferreira; Melo Hanchuk, Talita Diniz; Cardoso, Vanessa Bomfim; Kobarg, Jorg

2014-01-01

215

Survivable integrated grooming in multi-granularity optical networks  

NASA Astrophysics Data System (ADS)

Survivability is an important issue to ensure the service continuity in optical network. At the same time, with the granularity of traffic demands ranging from sub-wavelength-level to wavelength-level, traffic demands need to be aggregated and carried over the network in order to utilize resources effectively. Therefore, multi-granularity grooming is proposed to save the cost and reduce the number of switching ports in Optical-Cross Connects (OXCs). However, current works mostly addressed the survivable wavelength or waveband grooming. Therefore, in this paper, we propose three heuristic algorithms called Multi-granularity Dedicated Protection Grooming (MDPG), Multi-granularity Shared Protection Grooming (MSPG) and Multi-granularity Mixed Protection Grooming (MMPG), respectively. All of them are performed based on the Survivable Multi-granularity Integrated Auxiliary Graph (SMIAG) that includes one Wavelength Integrated Auxiliary Graph (WIAG) for wavelength protection and one waveBand Integrated Auxiliary Graph (BIAG) for waveband protection. Numerical results show that MMPG has the lowest average port-cost, the best resource utilization ratio and the lowest blocking probability among these three algorithms. Compared with MDPG, MSPG has lower average port-cost, better resource utilization ratio and lower blocking probability.

Wu, Jingjing; Guo, Lei; Wei, Xuetao; Liu, Yejun

2012-05-01

216

Protection schemes with waveband grooming in fault-tolerant multidomain optical networks  

NASA Astrophysics Data System (ADS)

In wavelength-division-multiplexing networks, the fault-tolerance is very important since failures may lead to a significant amount of data loss. At the same time, the waveband switching technique is very interesting since it can save switching ports in optical cross-connections. In addition, the hierarchical routing in multidomain optical networks is very challenging since the interdomain routing is based on aggregative virtual topology. However, previous works did not jointly consider the three issues. We propose two schemes, segment-based protection (SBP) and path-based protection (PBP), to provide the fault-tolerance and waveband grooming in multidomain optical networks. In SBP, for each connection we first compute an interdomain loose route based on virtual topology, and then we compute the intradomain exact path-pairs in each single domain traversed by the loose route based on physical topology. In PBP, for each connection we first compute an interdomain loose primary path and an interdomain loose backup path based on virtual topology, and then we compute the intradomain exact paths in each single domain traversed by the loose primary path and backup path based on the physical topology. To support multidomain waveband grooming, we present the layered auxiliary graph. Simulation results show that PBP performs better than SBP.

Guo, Lei; Cao, Jiannong; Wang, Xingwei; Jiang, Dingde; Yang, Ting

2010-04-01

217

Distributed signaling scheme with switching fabric status information in wavelength-routed optical networks  

NASA Astrophysics Data System (ADS)

In this paper, a new scheme to mitigate the connection setup time overheads in distributed control schemes for wavelength-routed optical networks is proposed. In this scheme, we consider the reconfiguration delay of switch fabrics in the distributed signaling protocols, which designated as the signaling with switch fabric status (SWFS). Based on the reconfiguration information being carried by signaling messages along with wavelength availability information, distributed wavelength assignment algorithm at the destination node will select a wavelength with the minimal switch reconfiguration delay along the lightpath to shorten average connection setup time. Simulation results indicate that the first-fit algorithm with switch status (S-FF) and random algorithm with switch status (S-RM) have the shorter setup time, lower switch ratio as well as better blocking performance than those of classic schemes. Especially, the proposed scheme significantly reduces the number of switch fabrics that need to be reconfigured. Moreover, we investigate the effect of number of add/drop ports of optical cross-connects (OXCs) on the blocking performance of the scheme. We find that when the number of add/drop ports of OXCs is larger than a base boundary, the network may achieve almost the best blocking performance of the distributed wavelength provisioning.

Lu, Lihua; Zeng, Qingji; Liu, Jimin; Hao, Yanna

2005-12-01

218

Localization of the spinal network associated with generation of hindlimb locomotion in the neonatal rat and organization of its transverse coupling system.  

PubMed

The segmental organization of the hindlimb locomotor pattern generators and the coordination of rhythmic motor activity were studied in isolated spinal cords of the neonatal rat. All lumbar segments and many thoracic and sacral segments of the cord exhibited an alternating left-right rhythm in the presence of serotonin (5-HT) and N-methyl-D-aspartate (NDMA). Other thoracic segments exhibited a synchronized left-right rhythm or an irregular bursting activity. Transection of the cord at the thoracolumbar or lumbosacral junction abolished the rhythmicity of nonlumbar segments and had no affect on the rhythmicity of lumbar segments. A fast alternating rhythm persisted in rostral lumbar segments after transection of the cord at mid-L3. A much slower alternating rhythm was found in the detached caudal lumbar segments after elevation of the NMDA concentration. These findings suggest that neurogenesis of hindlimb locomotion is not restricted to L1/L2, and that the lumbar pattern generators exhibited rostrocaudal specialization. An alternating left-right rhythm persisted in lumbar cords of midsagittally split preparations that were kept with either L1, L2, L3, or L4 as the only bilaterally intact segment. An alternating rhythm persisted also in preparations that were midsagittally split up to T13-T12, or down to L4. Extension of these lesions led to a bilaterally synchronous rhythm or to left-right independent rhythms in the lumbar cord. These results indicated that the transverse coupling system in the caudal-thoracic and lumbar segments in specialized and that left-right alternation in the lumbar cord can be carried out by the cross connectivity, which is relayed at least through the T12-L4 segments. Bath application of the glycine receptor antagonist strychnine, or the gamma-aminobutyric acid-A (GABAA) receptor blocker bicuculline, induced in the presence of NMDA and 5-HT a bilaterally synchronous rhythm in any intact or detached segment of the cord and in midsagittally split preparations with few bilaterally intact upper thoracic or lower sacral segments. A strychnine-resistant left-right alternating rhythm was found in the presence of 5-HT and NMDA in preparations that were treated with the non-NMDA receptor blocker 6-cyano-7-nitroquinoxaline (CNQX) before and during the application of strychnine. Subsequent washout of CNQX immediately induced a bilateral synchronous rhythm. These results suggest that the phase relation between the hemicords during the rhythm is determined by a dynamic interplay between the excitatory and inhibitory cross connectivity, and that this interplay can be modulated experimentally. Local application of strychnine to L2 kept bilaterally intact in midsagittally split preparations perturbed but did not completely block the alternating pattern of the rhythm induced by 5-HT and NMDA. Local application of bicuculline under the same conditions prolonged the cycle time and had no effect on left-right alternation. These results, together with those described above, suggest that left-right alternation is mediated mainly by strychnine-sensitive glycine receptors with possible contribution of strychnine-resistant glycine receptors and/or GABAA receptors. PMID:9084588

Kremer, E; Lev-Tov, A

1997-03-01

219

Detailed measurement of the magnitude and orientation of thermal gradients in lined boreholes for characterizing groundwater flow in fractured rock  

NASA Astrophysics Data System (ADS)

Recent developments have led to revitalization of the use of temperature logging for characterizing flow through fractured rock. The sealing of boreholes using water-filled, flexible impermeable liners prevents vertical cross connection between fractures intersecting the hole and establishes a static water column with a temperature stratification that mimics that in the surrounding formation. Measurement of the temperature profile of the lined-hole, water column (using a high sensitivity single-point probe achieving resolution on the order of 0.001 °C) has identified fractures with active flow under ambient groundwater conditions (without cross connecting flow along the borehole). Detection of flow in fractures was further improved with the use of a heater to create thermal disequilibrium in the active line source (ALS) technique and eliminate normal depth limitations in the process. This paper presents another advancement; detailed measurement of the magnitude and direction of the thermal gradient to characterize flow through fractured rock. The temperature within the water column is measured along the length of the lined hole using a temperature vector probe (TVP): four high sensitivity sensors arranged in a tetrahedral pattern oriented using three directional magnetometers. Based on these data, the horizontal and vertical components of the thermal field, as well as the direction of temperature gradient are determined, typically at depth intervals of less than 0.01 m. This probe was assessed and refined by trials in over 30 lined boreholes; the results from two holes through a fractured dolostone aquifer in Guelph, Ontario are used as exampled. Since no other device exists for measuring flow magnitude and direction under the ambient flow condition created by lined holes, the performance of the TVP is assessed by examining the reproducibility of the temperature measurements through an ALS test, and by the consistency of the results relative to other types of larger-scale information from the study area. Temperature profiles were measured in lined holes under both ambient thermal conditions and subject to ALS heating of the entire length of the holes to demonstrate resolution and reproducibility. The hydraulic gradient in three-dimensional space, based on pressure measurements from three depth discrete, multilevel monitoring systems in nearby holes, was used to independently estimate variations in groundwater flow directions. The characteristics of the hydraulic and thermal regimes are compared to assess response to changes in flow in a fractured rock system. When used in the lined holes, the level of detail provided by this multi-sensor probe is much greater than that provided by a single-sensor probe and this detail strongly supports inferences concerning the relative magnitude and direction of the flow. The results of this study indicate that the details of the thermal gradient can be measured and provides superior results compared to a conventional one dimensional temperature profile, thereby substantially enhancing the characterization of groundwater flow in fractured rock.

Pehme, Peeter; Parker, Beth L.; Cherry, John A.; Blohm, Detlef

2014-05-01

220

Plasma Pressure Generated Auroral Current System  

NASA Astrophysics Data System (ADS)

Anti-sunward directed azimuthal pressure gradients drive meridional currents perpendicular to the magnetic field in the dusk and dawn closed field line regions. These currents are closed through the auroral ionosphere consisting of a pair of upward and downward sheet field aligned currents (FAC) cross connected in the ionosphere. The upward currents are poleward (equatorward) on the dusk (dawn) side representing the region of visible aurora. Some of these auroras, especially on the dusk side, are in the form of arcs and can be present for several hours and stretch across several hours of local time, implying a large scale steady state current generator on closed field lines. Magnetometers on low earth orbit polar orbiting satellites e.g. FAST are ideal to measure the strength of the up and down FAC currents. To investigate whether the magnetospheric pressure gradients are sufficient to generate these auroral currents we used the T96 field model to define the geometry and map the field lines to their equatorial regions where the pressure gradient current generation is most effective. It was shown that in some cases the region between the up and down going FAC maps to 15 RE and with such a degree of field line stretching quiet time azimuthal pressure gradients of 0.01 nPa/Re are sufficient to generate the current needed to feed the observed auroral current loops. The pressure gradient generator requires either a high degree of field line stretching or larger gradients. With the THEMIS satellites direct measurements of the in situ plasma at the equator and the pressure gradients can be made. The high impedance of such a current generator has also important implications on auroral conjugacy.; Pressure gradient current system driving the auroral current system. FAST and THEMIS satellites make key measurements of the currents and the magnetospheric plasma.

Mende, S. B.

2012-12-01

221

Facilitation of Stepping with Epidural Stimulation in Spinal Rats: Role of Sensory Input  

PubMed Central

We investigated the role of afferent information during recovery of coordinated rhythmic activity of the hindlimbs in rats with a complete spinal cord section (~T8) and unilateral deafferentation (T12-S2) to answer the following questions: 1) Can bilateral stepping be generated with only afferent projections intact on one side? 2) Can the sensory input from the non-deafferented side compensate for the loss of the afferent input from the deafferented side through the crossed connections within the lumbosacral spinal cord? 3) Which afferent projections to the spinal cord from the non-deafferented side predominantly mediate the effect of epidural stimulation to facilitate stepping? Recovery of stepping ability was tested under the facilitating influence of epidural stimulation at the S1 spinal segment or epidural stimulation plus quipazine, a 5-HT agonist. All chronic spinal rats were able to generate stepping-like patterns on a moving treadmill on the non-deafferented, but not deafferented, side 3–7 weeks after surgery when facilitated by epidural stimulation. Adaptation to the loss of unilateral afferent input was evident at 7 weeks after surgery, when some movements occurred on the deafferented side. Spinal cord evoked potentials were observed on both sides, although middle (monosynaptic) and late (long-latency) responses were more prominent on the non-deafferented side. The afferent information arising from the non-deafferented side, however, eventually could mediate limited restoration of hindlimb movements on the deafferented side. These data suggest that facilitation of stepping with epidural stimulation is mediated primarily through ipsilateral afferents that project to the locomotor networks.

Lavrov, Igor; Courtine, Gregoire; Dy, Christine J.; van den Brand, Rubia; Fong, Andy J.; Gerasimenko, Yuri; Zhong, Hui; Roy, Roland R.; Edgerton, V. Reggie

2010-01-01

222

OXC management and control system architecture with scalability, maintenance, and distributed managing environment  

NASA Astrophysics Data System (ADS)

In this paper, we present the Optical Cross-Connect (OXC) Management Control System Architecture, which has the scalability and robust maintenance and provides the distributed managing environment in the optical transport network. The OXC system we are developing, which is divided into the hardware and the internal and external software for the OXC system, is made up the OXC subsystem with the Optical Transport Network (OTN) sub-layersí» hardware and the optical switch control system, the signaling control protocol subsystem performing the User-to-Network Interface (UNI) and Network-to-Network Interface (NNI) signaling control, the Operation Administration Maintenance & Provisioning (OAM&P) subsystem, and the network management subsystem. And the OXC management control system has the features that can support the flexible expansion of the optical transport network, provide the connectivity to heterogeneous external network elements, be added or deleted without interrupting OAM&P services, be remotely operated, provide the global view and detail information for network planner and operator, and have Common Object Request Broker Architecture (CORBA) based the open system architecture adding and deleting the intelligent service networking functions easily in future. To meet these considerations, we adopt the object oriented development method in the whole developing steps of the system analysis, design, and implementation to build the OXC management control system with the scalability, the maintenance, and the distributed managing environment. As a consequently, the componentification for the OXC operation management functions of each subsystem makes the robust maintenance, and increases code reusability. Also, the component based OXC management control system architecture will have the flexibility and scalability in nature.

Park, Soomyung; Joo, Seong-Soon; Yae, Byung-Ho; Lee, Jong-Hyun

2002-07-01

223

A multicast tree aggregation algorithm in wavelength-routed WDM networks  

NASA Astrophysics Data System (ADS)

Wavelength division multiplexing (WDM) has been considered a promising transmission technology in optical communication networks. With the continuous advance in optical technology, WDM network will play an important role in wide area backbone networks. Optical wavelength switching, compared with optical packet switching, is a more mature and more cost-effective choice for optical switching technologies. Besides, the technology of time division multiplexing in optical communication networks has been working smoothly for a long time. In the proposed research, the problem of multicast groups aggregation and multicast routing and wavelength assignment in wavelength-routed WDM network is studied. The optical cross connect switches in the problem are assumed to have limited optical multicast/splitting and TDM functionalities. Given the physical network topology and capacity, the objective is to maximize the total revenue by means of utmost merging multicast groups into larger macro-groups. The groups in the same macro-group will share a multicast tree to conduct data transmission. The problem is formulated as an optimization problem, where the objective function is to maximize the total revenue subject to capacity constraints of components in the optical network, wavelength continuity constraints, and tree topology constraints. The decision variables in the formulations include the merging results between groups, multicast tree routing assignment and wavelength assignment. The basic approach to the algorithm development for this model is Lagrangean relaxation in conjunction with a number of optimization techniques. In computational experiments, the proposed algorithms are evaluated on different network topologies and perform efficiently and effectively according to the experiment results.

Cheng, Hsu-Chen; Kuo, Chin-Chun; Lin, Frank Y.

2005-02-01

224

WDM transmission upgrade using low-cost uncooled components  

NASA Astrophysics Data System (ADS)

Cost-effective short-haul but high-capacity optical transport systems are becoming increasingly important for metropolitan-area and access applications; examples are metro-feeders, inter- or intra-office links between routers and cross-connects, and storage-area networks. Transmission links of this kind are characterized by distances of 10 to 100 km and typically use directly modulated lasers providing a high output power at a low device cost. Due to the inherent wavelength drift of uncooled system components, full spectrum CWDM is defined for up to 16 or 18 channels on a coarse 20-nm wavelength grid between 1270 and 1610 nm. To meet the demand for the increase of transmission capacity in the metro and access domain, there are several potential strategies to remove the capacity limit of 16×2.5 Gb/s found in conventional CWDM systems while still retaining the cost-effectiveness and the modular "pay as you grow" philosophy of CWDM. In this paper, we provide an overview of recent progress in the field of CWDM upgrade techniques. CWDM architectures with increased per channel bit-rates and sub-band DWDM channel overlays are reviewed and experimental results are presented. The particular combination of CWDM with DWDM sub-bands and bit-rate upgrades is expected to deliver the highest capacity gain. However, we also show that the suitability of the system for higher bit-rates hinges on the following considerations: the availability of low-cost 10-Gb/s DMLs at the respective wavelengths, the link budget and the chromatic dispersion of the deployed system.

Thiele, Hans J.; Winzer, Peter J.

2005-12-01

225

[Intravital observations on the development of the tumor vascular system in rats].  

PubMed

By using transparent chambers in rats, it proved possible to observe directly the normal vascular pattern and early neovascular response to solid tumor growth at high magnification. Morphologic studies of the vascularization patterns were performed daily by construction of photomontages from color instant film taken with a Polaroid camera. Noteworthy results obtained in this study were: In the normal subcutaneous tissue within the chamber, the main vascular pattern was similar to that described by Nicoll and Webb, showing the so-called "arcuate arteriolar pattern". The thoroughfare channel reported by Chambers and Zweifach was also observed. The establishment of new functional capillaries was observed within 2 weeks following the implantation of AH109A and AH272 tumors. The sprouts of newly formed vessels were seen originating at the arterial ends of the host capillaries, where the blood velocity was relatively high. The formation of intricate networks in the tumor occurred easily in a haphazard way; the three modes of network formation observed were sprouting, cross-connection and splitting. Progressive dilatation and tortuosity were observed in the preexisting vessels, especially capillaries and venules, in the neighborhood of the tumor implant. The arterioles, however, remained little altered and in a location almost identical to that at the time of tumor implantation. The vascular systems in the tumors were proved to parallel those in the normal organs from which they originated, from the microfocus stage to the large tumor stage. An understanding of the differences in the vascular architecture between normal and tumor tissue seems to be essential in order to elucidate the mechanism of enhancement of therapeutic effect by angiotensin II induced hypertension chemotherapy. PMID:2436577

Hori, K; Suzuki, M; Abe, I; Saito, S; Tanda, S

1987-03-01

226

New method for continuous transmissivity profiling in fractured rock.  

PubMed

A new method is presented to search for hydraulically transmissive features in open boreholes in bedrock. A flexible borehole liner made of a watertight, nylon fabric is filled with water to create a constant driving head to evert (reverse of invert) the liner down the hole so that the liner pushes the borehole water out into transmissive fractures or other permeable features. The descent rate is governed by the bulk transmissivity of the remaining permeable features below the liner. Initially, the liner descent rate or velocity is a measure of transmissivity (T) of the entire hole. As the everting liner passes and seals each permeable feature, changes in the liner velocity indicate the position of each feature and an estimate of T using the Thiem equation for steady radial flow. This method has been performed in boreholes with diameters ranging from 96 to 330?mm. Profiling commonly takes a few hours in holes 200- to 300-m long. After arrival of the liner at the bottom of the hole, the liner acts as a seal preventing borehole cross connection between transmissive features at different depths. Liner removal allows the hole to be used for other purposes. The T values determined using this method in a dolostone aquifer were found to be similar to the values from injection tests using conventional straddle packers. This method is not a replacement for straddle-packer hydraulic testing of specific zones where greater accuracy is desired; however, it is effective and efficient for scanning entire holes for transmissive features. PMID:23692626

Keller, Carl E; Cherry, John A; Parker, Beth L

2014-01-01

227

[Pollution and retro-pollution by the distribution system of medical gases].  

PubMed

The anaesthetic machine, the recovery room or the ICU ventilator as well as any other simple oxygenation device can be accidentally supplied with a "wrong" gas, or a mixture of "wrong" and "true" gases, or a gas containing chemical impurities, as a result of one of the following causes: a) the source of the medical gas pipeline supply contains a "wrong" gas or impurities; b) the gas pipeline is polluted by a "wrong" gas or solvents, introduced during the installation or maintenance of the pipeline; c) the pipeline is polluted by a wrong gas at a point of inter-connection or cross-connection of two pipelines; d) supply of a "wrong" gas through wrong quick couplers connected to the pipeline; e) back flow of a gas in another pipeline supply through a defective gas mixer, which is today the most common cause of pipeline contamination or retropollution. It occurs with some types of mixers in case of absence or malfunction of non-return valves, associated with a pressure difference between the two gas lines. The means of prevention, recognition and emergency treatment of these events include: a) systematic removal of mixers and flowmeter-mixers from supplies when not in use; b) periodical checking of these devices for an accidental communication between the gases to be mixed; c) systematic use of an oxygen analyser for a continuous measurement of FIO2, especially when the machine is connected to the N2O pipeline supply; d) the presence of a reserve cylinder of oxygen connected to every anaesthetic machine. PMID:7733522

Otteni, J C; Ancellin, J; Cazalaà, J B; Clergue, F

1994-01-01

228

Collagen fibre arrangement and functional crimping pattern of the medial collateral ligament in the rat knee.  

PubMed

Ligaments have been described as multifascicular structures with collagen fibres cross-connecting to each other or running straight and parallel also showing a waviness or crimping pattern playing as a shock absorber/recoiling system during joint motions. A particular collagen array and crimping pattern in different ligaments may reflect different biomechanical roles and properties. The aim of the study was to relate the 3D collagen arrangement in the crimping pattern of the medial collateral ligament (MCL) to its functional role. The MCL is one of the most injured ligaments during sports activities and an experimental model to understand the rate, quality and composition of ligaments healing. A deep knowledge of structure-function relationship of collagen fibres array will improve the development of rehabilitation protocols and more appropriate exercises for recovery of functional activity. The rat MCL was analysed by polarized light microscopy, confocal laser microscopy and scanning electron microscopy (SEM). Histomorphometric analysis demonstrated that MCL crimps have a smaller base length versus other tendons. SEM observations demonstrated that collagen fibres showing few crimps were composed of fibrils intertwining and crossing one another in the outer region. Confocal laser analyses excluded a helical array of collagen fibres. By contrast, in the core portion, densely packed straight collagen fibres ran parallel to the main axis of the ligament being interrupted both by planar crimps, similar to tendon crimps, and by newly described right-handed twisted crimps. It is concluded that planar crimps could oppose or respond exclusively to tensional forces parallel to the main ligament axis, whereas the right-handed twisted crimps could better resist/respond to a complex of tensional/rotational forces within the ligament thus opposing to an external rotation of tibia. PMID:20182866

Franchi, Marco; Quaranta, Marilisa; Macciocca, Maria; Leonardi, Luisa; Ottani, Vittoria; Bianchini, Paolo; Diaspro, Alberto; Ruggeri, Alessandro

2010-12-01

229

Waveband Grooming based on Layered Auxiliary Graph in multi-domain optical networks  

NASA Astrophysics Data System (ADS)

With the number of wavelengths on fibers keeps increasing, the size and the cost of Optical Cross-Connect (OXC) are greatly enhanced and then the control and management of optical switches become more and more complicated. Therefore, the technique called waveband switching is proposed to reduce the size and the cost of OXC; that is, to save the All-Optical (OOO) switching ports in OXC. However, the existing waveband switching algorithms are all limited in single-domain optical networks. Actually, with the scale of optical backbone keeps enlarging, the network is divided to multiple independent domains to perform the hierarchy routing for achieving the scalability. In order to reduce the size and the cost of OXC meanwhile to achieve the scalability in multi-domains, in this paper we propose a new heuristic algorithm called Waveband Grooming with Layered Auxiliary Graph (WGLAG) since the waveband grooming problem is the NP-hard to perform the inter-domain routing based on the virtual topology of multi-domain network and the intra-domain routing based on the physical topology of single-domain network. In intra-domain routing with waveband grooming of each single-domain, we propose the Layered Auxiliary Graph (LAG) that includes one virtual topology layer and multiple waveband-plane layers to compute a single-hop, or multi-hop or hybrid waveband route for each connection request based on the sub-path waveband grooming scheme. Simulation results show that, WGLAG not only can effectively save more switching ports to reduce the cost of OXC but also can obtain lower blocking probability than other algorithm.

Guo, Lei; Cao, Jiannong; Wang, Xingwei; Jiang, Dingde; Yang, Ting

2010-06-01

230

Assessing the Role of Sewers and Atmospheric Deposition as Nitrate Contamination Sources to Urban Surface Waters using Stable Nitrate Isotopes  

NASA Astrophysics Data System (ADS)

Excess nitrate (NO3-) contributes to the overall degraded quality of streams in many urban areas. These systems are often dominated by impervious surfaces and storm sewers that can route atmospherically deposited nitrogen, from both wet and dry deposition, to waterways. Moreover, in densely populated watersheds there is the potential for interaction between urban waterways and sewer systems. The affects of accumulated nitrate in riverine and estuary systems include low dissolved oxygen, loss of species diversity, increased mortality of aquatic species, and general eutrophication of the waterbody. However, the dynamics of nitrate pollution from each source and it’s affect on urban waterways is poorly constrained. The isotopes of nitrogen and oxygen in nitrate have been proven effective in helping to distinguish contamination sources to ground and surface waters. In order to improve our understanding of urban nitrate pollution sources and dynamics, we examined nitrate isotopes (?15N and ?18O) in base- and stormflow samples collected over a two-year period from a restored urban stream in Pittsburgh, Pennsylvania (USA). Nine Mile Run drains a 1,600 hectare urban watershed characterized by 38% impervious surface cover. Prior work has documented high nitrate export from the watershed (~19 kg NO3- ha-1 yr-1). Potential nitrate sources to the watershed include observed sewer overflows draining directly to the stream, as well as atmospheric deposition (~23 kg NO3- ha-1 yr-1). In this and other urban systems with high percentages of impervious surfaces, there is likely minimal input from nitrate derived from soil or fertilizer. In this presentation, we examine spatial and temporal patterns in nitrate isotopic composition collected at five locations along Nine Mile Run characterized by both sanitary and combined-sewer cross-connections. Preliminary isotopic analysis of low-flow winter streamwater samples suggest nitrate export from Nine Mile Run is primarily influenced by inputs of human waste despite high rates of atmospheric nitrate deposition. Further isotopic analysis of nitrate will examine seasonal variations in nitrate sources; compare nitrate dynamics and sources during low- versus high-flows, and the influence of interannual climatic variability on nitrate export.

Sikora, M. T.; Elliott, E. M.

2009-12-01

231

GABA-receptor-independent dorsal root afferents depolarization in the neonatal rat spinal cord.  

PubMed

Dorsal root afferent depolarization and antidromic firing were studied in isolated spinal cords of neonatal rats. Spontaneous firing accompanied by occasional bursts could be recorded from most dorsal roots in the majority of the cords. The afferent bursts were enhanced after elevation of the extracellular potassium concentration ([K+]e) by 1-2 mM. More substantial afferent bursts were produced when the cords were isolated with intact brain stems. Rhythmic afferent bursts could be recorded from dorsal roots in some of the cords during motor rhythm induced by bath-applied serotonin and N-methyl--aspartate (NMDA). Bilaterally synchronous afferent bursts were produced in pairs of dorsal roots after replacing the NaCl in the perfusate with sodium-2-hydroxyethansulfonate or after application of the gamma-aminobutyric acid-A (GABAA) receptor antagonist bicuculline with or without serotonin (5-HT) and NMDA. Antidromic afferent bursts also could be elicited under these conditions by stimulation of adjacent dorsal roots, ventrolateral funiculus axons, or ventral white commissural (VWC) fibers. The antidromic bursts were superimposed on prolonged dorsal root potentials (DRPs) and accompanied by a prolonged increase in intraspinal afferent excitability. Surgical manipulations of the cord revealed that afferent firing in the presence of bicuculline persisted in the hemicords after hemisection and still was observed after removal of their ventral horns. Cutting the VWC throughout its length did not perturb the bilateral synchronicity of the discharge. These findings suggest that the activity of dorsal horn neurons is sufficient to produce the discharge and that the bilateral synchronicity can be maintained by cross connectivity that is relayed from side to side dorsal to the VWC. Antagonists of GABAB, 5-HT2/5-HT1C, or glutamate metabotropic group II and III receptors could not abolish afferent depolarization in the presence of bicuculline. Depolarization comparable in amplitude to DRPs, could be produced in tetrodotoxin-treated cords by elevation of [K+]e to the levels reported to develop in the neonatal rat spinal cord in response to dorsal root stimulation. A mechanism involving potassium transients produced by neuronal activity therefore is suggested to be the major cause of the GABA-independent afferent depolarization reported in our study. Possible implications of potassium transients in the developing and the adult mammalian spinal cord are discussed. PMID:9582230

Kremer, E; Lev-Tov, A

1998-05-01

232

High-Resolution Flow Logging for Hydraulic Characterization of Boreholes and Aquifer Flow Zones at Contaminated Bedrock Sites  

NASA Astrophysics Data System (ADS)

In the past, flow logging was largely restricted to the application of spinner flowmeters to determine flow-zone contributions in large-diameter production wells screened in highly transmissive aquifers. Development and refinement of tool-measurement technology, field methods, and analysis techniques has greatly extended and enhanced flow logging to include the hydraulic characterization of boreholes and aquifer flow zones at contaminated bedrock sites. State-of-the-art in flow logging will be reviewed, and its application to bedrock-contamination investigations will be presented. In open bedrock boreholes, vertical flows are measured with high-resolution flowmeters equipped with flexible rubber-disk diverters fitted to the nominal borehole diameters to concentrate flow through the measurement throat of the tools. Heat-pulse flowmeters measure flows in the range of 0.05 to 5 liters per minute, and electromagnetic flowmeters measure flows in the range of 0.3 to 30 liters per minute. Under ambient and low-rate stressed (either extraction or injection) conditions, stationary flowmeter measurements are collected in competent sections of the borehole between fracture zones identified on borehole-wall images. Continuous flow, fluid-resistivity, and temperature logs are collected under both sets of conditions while trolling with a combination electromagnetic flowmeter and fluid tool. Electromagnetic flowmeters are used with underfit diverters to measure flow rates greater than 30 liters per minute and suppress effects of diameter variations while trolling. A series of corrections are applied to the flow-log data to account for the zero-flow response, bypass, trolling, and borehole-diameter biases and effects. The flow logs are quantitatively analyzed by matching simulated flows computed with a numerical model to measured flows by varying the hydraulic properties (transmissivity and hydraulic head) of the flow zones. Several case studies will be presented that demonstrate the integration of flow logging in site-characterization activities framework; 2) evaluate cross-connection effects and determine flow-zone contributions to water-quality samples from open boreholes; and 3) design discrete-zone hydraulic tests and monitoring-well completions.

Williams, J. H.; Johnson, C. D.; Paillet, F. L.

2004-05-01

233

IP over optical layer restoration: architecture, design, and analysis  

NASA Astrophysics Data System (ADS)

Optical layer capacity and unit cost improvements are basic to the rapid growth of IP networks. However, the new rapid reconfiguration and restoration capabilities of the optical layer have been sparingly utilized by IP network operators. This is consistent with the economics: the widely deployed optical layer architecture based on a "discrete" optical crossconnect (DOXC - one not integrated into the WDM) incurs heavy interface costs. In addition, there are architectural and control issues which are roadblocks to IP exploitation of rapid optical layer agility. In the first part of the paper, we describe a next generation all-optical architecture based on OXCs integrated with the WDM ("IOXCs"), and one instantiation of this architecture using a class of reconfigurable degree-N optical add-drop multiplexer (OADM). A new shared mesh restoration mechanism based on hot standbys is designed to overcome slow convergence and transient behaviors that are typical in all-optical networks. A series of economic comparisons are made on both a 120-node hypothetical national network and a smaller express backbone network to demonstrate the cost effectiveness of the new IOXC-based restoration in comparison to the IP layer restoration after some optical layer failure that results in one or more IP link failures. In the IP over Optical architecture, the Optical Layer can provide its IP clients rapid and efficient restoration for IP link failures that are due to some optical layer failure; however its inability to protect against router and router interface failures erodes its attractiveness. In the second part of the paper, we propose a joint IP/Optical restoration mechanism to deal with this. It is suitable for IP offices with at least two backbone routers and an optical cross-connect. The OXC is used to re-terminate OC-48/OC-192 links from a failed backbone router to its mate. The entire interoffice portion of the re-terminated link is reused, thus minimizing the amount of additional inter-office capacity required to protect against router failures. The proposed scheme is also applicable to restoration for router interface failures as well as to cases with single backbone router office architecture.

Chiu, Angela L.; Strand, John

2005-12-01

234

BOOK REVIEW: Equations of Motion in General Relativity Equations of Motion in General Relativity  

NASA Astrophysics Data System (ADS)

Devoted exclusively to the problem of motion in general relativity, this book by H. Asada, T. Futamase, and P. A. Hogan is highly welcome to close up a gap in the book sector presenting a concise account of theoretical developments and results on gravitational equations of motion achieved since the discovery of the binary neutron star system PSR 1913+16 in 1974. For the most part, the book is concerned with the development and application of the important post-Newtonian approximation (PNA) framework which allows for highly efficient approximate analytic solutions of the Einstein field equations for many-body systems in terms of a slow-motion and weak-field ordering parameter. That approximation scheme is shown to be applicable also to the external motion of strongly self-gravitating objects if their internal dynamics is frozen in (strong field point particle limit) and the external conditions fit. Relying on the expertise of the authors, the PNA framework is presented in a form which, at the 1PNA level, had become famous through the work by Einstein, Infeld and Hoffmann in 1938; therein, surface integrals over gravitational field expressions in the outside-body regime play a crucial role. Other approaches which also succeeded with the highest achieved PNA level so far are mentioned too, if not fully exhaustively with respect to the highest, the 3.5PNA level which contains the inverse power of the speed of light to the seventh order. Regarding the 3PNA, the reader gains a clear understanding of how the equations of motion for binary systems with compact components come about. Remarkably, no deviation from four-dimensional space-time is needed. Various explicit analytic expressions are derived for binary systems: the periastron advance and the orbital period at the 2PNA, the orbital decay through gravitational radiation reaction at the 2.5PNA, and effects of the gravitational spin-orbit and spin-spin couplings on the orbital motion. Also the propagation of light-like signals in gravitational fields of binary systems is treated, which is important for a precise interpretation of pulsar observation measurements. Based on original research by the authors, a detailed presentation is given of a mathematical scheme which makes feasible the treatment of small black holes in background space-times. Using that approach, the equations of motion of small charged black holes are derived in vacuum Einstein-Maxwell space-times without encountering infinities, showing up electromagnetic radiation reaction, background field, and tail forces. At this stage, the book defines various issues to be tackled in future research within the given formalism, such as a physical understanding of the very structure of the tail contribution or a more detailed calculation of the motion of a small Schwarzschild black hole in an external vacuum gravitational field. A unique chapter is devoted to the choreographic three-body solution of the 1PNA dynamics, also mentioning the 2PNA dynamics, in the form of figure-eight configurations. The emitted gravitational waves are shown, and a discussion of their observability in future gravitational wave astronomy is given. Four appendices support and complement the main part of the book. Here, the far zone non-contribution to the equations of motion at 3PNA is carefully investigated, forces resulting from the extendedness of objects are presented in analytic form, null geodesic congruences with their optical scalars are discussed, and the perturbed vacuum Einstein-Maxwell field equations are given. The book delivers a very readable account of the problem of motion in general relativity. It covers the state of the art up to the years 2006/8 and presents a plethora of interesting and important topics and results. Whenever appropriate, connection with observation is made. A reader with good post-introductory knowledge of the theory of general relativity should find easy access to the book, and will surely benefit from the mathematical and conceptual issues elaborated on therein. Being of observational relevance too, the

Schäfer, Gerhard

2012-03-01

235

Detection of Human Sewage in Urban Stormwater Using DNA Based Methods and Stable Isotope Analysis  

NASA Astrophysics Data System (ADS)

Urban stormwater is a major source of fecal indicator bacteria in the Milwaukee River Basin, a major watershed draining to Lake Michigan. Much of the watershed is in highly urbanized areas and Escherichia coli (E. coli) levels have been found to be 20,000 CFU per 100 ml in the estuary leading to Lake Michigan. Aging infrastructure and illicit cross connections may allow sewage to infiltrate the stormwater system and could contribute both fecal indicator bacteria and human pathogens to these waters. We conducted extensive sampling of stormwater outfalls in the lower reaches of three major tributaries. Three outfalls along the heavily urbanized Kinnickinnick (KK) were found to have geometric mean E. coli and enterococci levels of 16,200 and 28,700 CFU/100 ml, respectively. Four outfalls along the Menomonee River, draining both suburban and urban areas, had geometric mean E. coli and enterococci levels of 14,700 and 12,800 CFU/100 ml, respectively. These seven outfalls had more than 60% of the samples positive for human specific Bacteroides genetic marker (n=46), suggesting the presence of human sources. In addition, two outfalls on Lincoln Creek, a smaller tributary of the Milwaukee River, had geometric mean E. coli and enterococci levels of 16,700 and 14,900 CFU per 100 ml, respectively. The human specific Bacteroides marker was positive in nearly 90% of the samples (n=24). Subsequent virus testing at one of these outfalls confirmed human pathogens were present with adenovirus detected at 1.3 x 10E3 genomic equivalents (ge)/L, enterovirus at 1.9 x 10E4 ge/L and G1 norovirus at 1.5 x 10E3 ge/L; these values are similar to concentrations found in sewage. Stable isotope studies were conducted in the three tributaries to investigate the relationship between delta C and delta N isotopic composition and microbiological quality of this urban freshwater system. This work is based on the premise that the organic matter of the stormwater will have a stable isotopic signature related to the mixed organic matter sources in polluted stormwater runoff, and that this signal will distinct from untreated sanitary sewage. Stable isotope signatures of stormwater and untreated sewage were determined and compared with the rivers. Isotopic values of stormwater was delta 15N = 1.1 ± 2 %; delta 13C = -25.5 ± 3 % and sewage was delta 15N = -1.9 ± 0.2 %; delta 13C = -23.6 ± 0.3. Suspended particular organic matter (SPOM) of Milwaukee River showed depleted delta 13C (-28.6 ± 1.6 %) and enriched delta 15N (7.7 ± 1.9 %) values. SPOM of the KK River exhibited the most depleted delta 15N (0.2 ± 1.6 %) and enriched delta 13C (-24.8 ± 1.8 %) isotopic values. Menomonee River SPOM showed intermediate isotopic values. The delta 13C values of each river and the estuary enriched significantly throughout the summer storm periods. The isotope signals in the KK and Menomonee were indicative of stormwater runoff and sewage contamination. These results suggest that unrecognized sewage inputs are chronically present and may be delivered through urban stormwater systems. DNA based methods combined with isotope analysis may provide a useful tool for urban watershed assessments and to identify sewage inputs. Delineating the relative contribution of stormwater and sewage to overall degraded water quality might give the first indication of the impact of these sources on the Michigan Lake waters.

McLellan, S. L.; Malet, N.; Sauer, E.; Mueller-Spitz, S.; Borchardt, M.

2008-12-01

236

Streamflow, water quality, and contaminant loads in the lower Charles River Watershed, Massachusetts, 1999-2000  

USGS Publications Warehouse

Streamflow data and dry-weather and stormwater water-quality samples were collected from the main stem of the Charles River upstream of the lower Charles River (or the Basin) and from four partially culverted urban streams that drain tributary subbasins in the lower Charles River Watershed. Samples were collected between June 1999 and September 2000 and analyzed for a number of potential contaminants including nitrate (plus nitrite), ammonia, total Kjeldahl nitrogen, phosphorus, cadmium, chromium, copper, lead, and zinc; and water-quality properties including specific conductance, turbidity, biochemical oxygen demand, fecal coliform bacteria, Entero-coccus bacteria, total dissolved solids, and total suspended sediment. These data were used to identify the major pathways and to determine the magnitudes of contaminants loads that contribute to the poor water quality of the lower Charles River. Water-quality and streamflow data, for one small urban stream and two storm drains that drain subbasins with uniform (greater than 73 percent) land use (including single-family residential, multifamily residential, and commercial), also were collected. These data were used to elucidate relations among streamflow, water quality, and subbasin characteristics. Streamflow in the lower Charles River Watershed can be characterized as being unsettled and flashy. These characteristics result from the impervious character of the land and the complex infrastructure of pipes, pumps, diversionary canals, and detention ponds throughout the watershed. The water quality of the lower Charles River can be considered good?meeting water-quality standards and guidelines?during dry weather. After rainstorms, however, the water quality of the river becomes impaired, as in other urban areas. The poor quality of stormwater and its large quantity, delivered over short periods (hours and days), together with illicit sanitary cross connections, and combined sewer overflows, results in large contaminant loads that appear to exceed the river?s assimilative capacity. Annual contaminant loads from stormwater discharges directly to the lower Charles River are large, but most dry-weather and stormwater contaminant loads measured in this study originate from upstream of the Watertown Dam and are delivered to the lower Charles River in mainstem flows. An exception is fecal coliform bacteria. Stony Brook, a large tributary influenced by combined sewer overflow, contributed almost half of the annual fecal coliform load to the lower Charles River for Water Year 2000. Much of this fecal coliform bacteria load is discharged from Stony Brook to the lower Charles River during rain-storms. Estimated stormwater loads for future conditions suggest that sewer separation in the Stony Brook Subbasin might reduce loads of constituents associated with sewage but increase loads of constituents associated with street runoff. The unique environment offered by the lower Charles River must be considered when the environmental implications of large contaminant loads are interpreted. In particular, the lower Charles River has low hydraulic gradients, a lack of tidal flushing, a lack of natural uncontaminated sediment from erosion of upstream uncontaminated soils, and an anoxic, sulfide-rich bottom layer that forms a non-tidal salt wedge in the downstream part of the lower Charles River. Individually and in combination, these characteristics may increase the likelihood of adverse effects of some contaminants on the water, biota, and sediment of the lower Charles River.

Breault, Robert F.; Sorenson, Jason R.; Weiskel, Peter K.

2002-01-01

237

A Multiple-Tracer Approach for Identifying Sewage Sources to an Urban Stream System  

USGS Publications Warehouse

The presence of human-derived fecal coliform bacteria (sewage) in streams and rivers is recognized as a human health hazard. The source of these human-derived bacteria, however, is often difficult to identify and eliminate, because sewage can be delivered to streams through a variety of mechanisms, such as leaking sanitary sewers or private lateral lines, cross-connected pipes, straight pipes, sewer-line overflows, illicit dumping of septic waste, and vagrancy. A multiple-tracer study was conducted to identify site-specific sources of sewage in Accotink Creek, an urban stream in Fairfax County, Virginia, that is listed on the Commonwealth's priority list of impaired streams for violations of the fecal coliform bacteria standard. Beyond developing this multiple-tracer approach for locating sources of sewage inputs to Accotink Creek, the second objective of the study was to demonstrate how the multiple-tracer approach can be applied to other streams affected by sewage sources. The tracers used in this study were separated into indicator tracers, which are relatively simple and inexpensive to apply, and confirmatory tracers, which are relatively difficult and expensive to analyze. Indicator tracers include fecal coliform bacteria, surfactants, boron, chloride, chloride/bromide ratio, specific conductance, dissolved oxygen, turbidity, and water temperature. Confirmatory tracers include 13 organic compounds that are associated with human waste, including caffeine, cotinine, triclosan, a number of detergent metabolites, several fragrances, and several plasticizers. To identify sources of sewage to Accotink Creek, a detailed investigation of the Accotink Creek main channel, tributaries, and flowing storm drains was undertaken from 2001 to 2004. Sampling was conducted in a series of eight synoptic sampling events, each of which began at the most downstream site and extended upstream through the watershed and into the headwaters of each tributary. Using the synoptic sampling approach, 149 sites were sampled at least one time for indicator tracers; 52 of these sites also were sampled for confirmatory tracers at least one time. Through the analysis of multiple-tracer levels in the synoptic samples, three major sewage sources to the Accotink Creek stream network were identified, and several other minor sewage sources to the Accotink Creek system likely deserve additional investigation. Near the end of the synoptic sampling activities, three additional sampling methods were used to gain better understanding of the potential for sewage sources to the watershed. These additional sampling methods included optical brightener monitoring, intensive stream sampling using automated samplers, and additional sampling of several storm-drain networks. The samples obtained by these methods provided further understanding of possible sewage sources to the streams and a better understanding of the variability in the tracer concentrations at a given sampling site. Collectively, these additional sampling methods were a valuable complement to the synoptic sampling approach that was used for the bulk of this study. The study results provide an approach for local authorities to use in applying a relatively simple and inexpensive collection of tracers to locate sewage sources to streams. Although this multiple-tracer approach is effective in detecting sewage sources to streams, additional research is needed to better detect extremely low-volume sewage sources and better enable local authorities to identify the specific sources of the sewage once it is detected in a stream reach.

Hyer, Kenneth Edward

2007-01-01