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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

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

6

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)

1997-09-01

7

Supercontinuum generation with a figure-eight fiber laser  

Microsoft Academic Search

We use a figure-eight fibre laser with a photonic crystal fibre NALM (nonlinear amplifying loop mirror) to produce a moderate supercontinuum from 1440 nm - 1680 nm in highly nonlinear dispersion shifted fibre. We also observe a 743 nm band in the fluorescence of the erbium doped amplifier outside the figure-eight fibre laser.

Diethelm Schmieder; Pieter L. Swart; Ronnie Kritzinger

2007-01-01

8

The construction of DNA molecules of figure-eight structure  

Microsoft Academic Search

Using DNA molecules to construct a structural scaffold for nanotechnology is largely accepted. In this article, we report on two methods for constructing a figure-eight structure of DNA molecules having a relatively high yield that could be used further as a scaffold for nanotechnology applications. In the first method, two plasmids were constructed that, on digestion with a restriction endonuclease

Hadar Nir; Yoav Eichen; Gadi Schuster

2005-01-01

9

Approximate action-angle variables for the figure-eight and periodic three-body orbits  

NASA Astrophysics Data System (ADS)

We use the maximally permutation-symmetric set of three-body coordinates that consist of the “hyper-radius” R=?2+?2, the “rescaled area of the triangle” (3)/(2R2)|?×?|), and the (braiding) hyperangle ?=arctan((2?·?)/(?2-?2)) to analyze the “figure-eight” choreographic three-body motion discovered by Moore [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.70.3675 70, 3675 (1993)] in the Newtonian three-body problem. Here ?,? are the two Jacobi relative coordinate vectors. We show that the periodicity of this motion is closely related to the braiding hyperangle ?. We construct an approximate integral of motion G? that together with the hyperangle ? forms the action-angle pair of variables for this problem and show that it is the underlying cause of figure-eight motion’s stability. We construct figure-eight orbits in two other attractive permutation-symmetric three-body potentials. We compare the figure-eight orbits in these three potentials and discuss their generic features, as well as their differences. We apply these variables to two new periodic, but nonchoreographic, orbits: One has a continuously rising ? in time t, just like the figure-eight motion, but with a different, more complex, periodicity, whereas the other one has an oscillating ?(t) temporal behavior.

Šuvakov, Milovan; Dmitrašinovi?, V.

2011-05-01

10

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

NASA Astrophysics Data System (ADS)

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.

Nicholson, J. W.; Andrejco, M.

2006-09-01

11

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

12

Development of Locomotor Activity of Rat Pups in Figure-Eight Mazes.  

National Technical Information Service (NTIS)

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 com...

P. H. Ruppert K. F. Dean L. W. Reiter

1985-01-01

13

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...

14

Dissipative soliton resonance in a passively mode-locked figure-eight fiber laser.  

PubMed

The generation of mode-locked rectangular pulses operating in dissipative soliton resonance (DSR) region is demonstrated in an erbium-doped figure-eight fiber laser with net anomalous dispersion. The duration of the wave-breaking-free rectangular pulse broadens with the increase of pump power. At a maximum pump power of 341 mW, the pulse energy can be up to 3.25 nJ with a repetition rate of 3.54 MHz. Particularly, the spectrum of rectangular pulse operating in DSR exhibits conventional soliton sidebands. The observed results show that the formation of pulse operating in DSR region is independent of mode-locking techniques, which may be helpful for further understanding the DSR phenomenon. PMID:23389220

Wang, Shi-Ke; Ning, Qiu-Yi; Luo, Ai-Ping; Lin, Zhen-Bin; Luo, Zhi-Chao; Xu, Wen-Cheng

2013-01-28

15

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

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.

1992-06-01

17

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

18

Design approaches and parameters for magnetically levitated transport systems. [Null flux suspension (Maglev)  

SciTech Connect

Mechanically levitated transport system approaches are assessed with regard to thrust power needs, track cost, suspension stability, and safety. The null flux suspension appears as the favored approach, having the least thrust power requirements, highest stability, and lowest amount of track material. Various null flux configurations are described together with their operating parameters. The Linear Synchronous Motor (LSM) propulsion system is also described for propelling the suspended vehicles. Cryogenics and superconductivity aspects are discussed and the effect of high T/sub c/ superconductors evaluated. 13 refs., 16 figs., 2 tabs.

Danby, G.T.; Powell, J.R.

1988-01-01

19

Modular wavelength selective cross-connects  

Microsoft Academic Search

Optical cross-connects are an enabling technology for transparent mesh networking, but are better implemented in modular fashion for economic benefits. Various cross-connect constructs are reviewed and found that using wavelength-selective switches offers the greatest advantages.

D. Marom

2004-01-01

20

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); Shaaf, J. [BDM Federal, Inc., Huntsville, AL (United States); Rote, D. [Argonne National Lab., IL (United States)

1995-11-01

21

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

22

Control Services Based on Digital Cross-Connect Systems  

Microsoft Academic Search

The basic elements of the architecture underlying the ACCUNET®family of digital services, the role of digital cross-connect systems, their associated support systems, and the services they provide are described. As an illustrative example, a description of the deployment of customer controlled reconfiguration (CCR) and the control system design considerations for user interfaces is provided.

W. Hutcheson; T. Snyder

1987-01-01

23

A hybrid MEMS-waveguide wavelength selective cross connect  

Microsoft Academic Search

A 16-channel 100-GHz-spacing wavelength selective cross connect is demonstrated using a combination of planar waveguides and MEMS piston-mirrors. Interswitch crosstalk is eliminated and switching speed is an order of magnitude faster than typical thermooptic switches. The power consumption is smaller than one microwatt per switch. An extinction ratio of 20 dB and an insertion loss of 10.6 dB are demonstrated.

D. T. Fuchs; C. R. Doerr; V. A. Aksyuk; M. E. Simon; L. W. Stulz; S. Chandrasekhar; L. L. Buhl; M. Cappuzzo; L. Gomez; A. Wong-Foy; E. Laskowski; E. Chen; R. Pafchek

2004-01-01

24

Synthesis of dual-microring-resonator cross-connect filters.  

PubMed

A new type of resonant, waveguided, 2 x 2 cross-connect optical filter is proposed and synthesized using a microwave filter analog. The optical passbands of the device are determined using 2D scattering matrix theory and the desired response is generated via a synthesis for a combined singly and doubly terminated circuit. This synthesis realizes the microring coupling coefficients necessary for maximally flat infrared spectral response. Closed-form analytical solutions are presented. Devices containing two, four, and six microrings were investigated. PMID:19495359

Emelett, S; Soref, R

2005-06-13

25

Wavelength selective cross connect using arrayed waveguide lens multi-wavelength filters  

Microsoft Academic Search

We present an experimental demonstration of a partially equipped 128×128 OC-192 novel wavelength selective cross connect using a broadcast-and-select architecture. Novel silica multi-wavelength filters are key elements in the cross connect

C. R. Doerr; B. M. Mikkelsen; G. Raybon; P. Schiffer; W. Stulz; M. Zirngibl; G. Wilfong; M. Cappuzzo; E. Laskowski; A. Paunescu; L. Gomez; J. Gates

1999-01-01

26

Dual-keel electrodynamic maglev system  

DOEpatents

A propulsion and stabilization system with a plurality of superconducting magnetic devices affixed to the dual-keels of a vehicle, where the superconducting magnetic devices produce a magnetic field when energized. The system also includes a plurality of figure-eight shaped null-flux coils affixed to opposing vertical sides of slots in a guideway. The figure-eight shaped null-flux coils are vertically oriented, laterally cross-connected in parallel, longitudinally connected in series, and continue the length of the vertical slots providing levitation and guidance force. An external power source energizes the figure-eight shaped null-flux coils to create a magnetic traveling wave that interacts with the magnetic field produced by the superconducting magnets to impart motion to the vehicle.

He, Jianliang (Naperville, IL); Wang, Zian (Downers Grove, IL); Rote, Donald M. (Lagrange, IL); Coffey, Howard T. (Darien, IL); Hull, John R. (Westmont, IL); Mulcahy, Thomas M. (Western Springs, IL); Cal, Yigang (Woodridge, IL)

1996-01-01

27

Silicon cross-connect filters using microring resonator coupled multimode-interference-based waveguide crossings.  

PubMed

We report silicon cross-connect filters using microring resonator coupled multimode-interference (MMI) based waveguide crossings. Our experiments reveal that the MMI-based cross-connect filters impose lower crosstalk at the crossing than the conventional cross-connect filters using plain crossings, while offering a nearly symmetric resonance line shape in the drop-port transmission. As a proof-of-concept for cross-connection applications, we demonstrate on a silicon-on-insulator substrate (i) a 4-channel 1 x 4 linear-cascaded MMI-based cross-connect filter, and (ii) a 2-channel 2 x 2 array-cascaded MMI-based cross-connect filter. PMID:18545578

Xu, Fang; Poon, Andrew W

2008-06-01

28

Cross-connection control of the potable water lines at Oak Ridge National Laboratory  

Microsoft Academic Search

A 1991 independent U.S. Department of Energy (DOE) audit of Oak Ridge National Laboratory (ORNL) identified the need for establishing a cross-connection control program for the potable and nonpotable water systems at the facility. An informal cross-connection policy had been in place for some time, but the formal implementation of a cross-connection program brought together individuals from the Quality Engineering

1996-01-01

29

Interference-based MEMS\\/waveguide wavelength-selective cross-connect  

Microsoft Academic Search

A 16-channel wavelength selective cross-connect is demonstrated using planar waveguides and MEMS piston-mirrors. Compared to thermooptic switching, inter-switch crosstalk and power consumption are eliminated

D. T. Fuchs; C. R. Doerr; A. Aksyuk; M. E. Simon; R. Pafchek; L. W. Stulz

2002-01-01

30

Cross-connection control of the potable water lines at Oak Ridge National Laboratory  

SciTech Connect

A 1991 independent U.S. Department of Energy (DOE) audit of Oak Ridge National Laboratory (ORNL) identified the need for establishing a cross-connection control program for the potable and nonpotable water systems at the facility. An informal cross-connection policy had been in place for some time, but the formal implementation of a cross-connection program brought together individuals from the Quality Engineering and Inspection Section of the Office of Quality Programs and Inspection, Industrial Hygiene, Health Physics, Plant and Equipment Division, and the Atomic Trade and Labor Council. In January 1994 a Cross-Connection Control Committee was established at ORNL to identify potential and actual cross connections between potable and nonpotable water systems. Potable water is safe to drink, and nonpotable or process water (e.g., sewage, laboratory wastewater, cooling water, and tower water) is not intended for human consumption, washing of the body, or food preparation. The program is intended to conform with the Federal Safe Drinking Water Act Amendment of 1986 and with state and local regulations. Although the Occupational Safety and Health Administration addresses cross-connection functions, it does not define specific program requirements. The program at ORNL is designed to ensure that necessary recommendations are implemented to safeguard all internal and external potable water distribution lines. Program responsibilities include a thorough engineering assessment to (1) identify the potable water lines, (2) identify any existing or potential cross connections, and (3) inspect the integrity of the water lines. If any cross-connection deficiencies are found, corrective actions are initiated according to industry standards.

Moore, R.M.

1996-04-01

31

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

32

Characterization of pre-cross-connected trails for optical mesh network protection  

NASA Astrophysics Data System (ADS)

Recently there has been interest in so-called pre-cross-connected protection architectures for optical networks. The main benefit of pre-cross-connected protection is that multiple cross-connection actions are not required in real time at the time of failure. This addresses the practical concern that, in a transparent optical network, one may not be able to make a series of protection path-forming cross-connections in a succession of optical spans with certainty that the resultant end-to-end connection has optical path integrity. Self-healing rings, p-cycles, and preconnected linear segment protection are examples of prior methods that employ prefailure cross-connection of protection capacity but are not end-to-end path-oriented. More recent work has proposed pre-cross-connected trails (PXTs), which are fully preconnected linear path-protecting structures. The same work also provided an online heuristic algorithm for generating PXT network designs. However, important and interesting properties such as length and cyclicity of the PXT structures remained to be characterized. We delve further into PXT network design, attempting to validate claims made previously and to understand the structural and operational properties of PXTs. This involves reimplementation of and experimentation with the above heuristic. Results show that heuristically obtained designs frequently contain PXTs of great total length and high complexity, as well as other PXTs that are equivalent to 1+1 automatic protection switching (APS) arrangements. Through diagramming and statistical analysis of PXT characteristics we give the first intuitive appreciation of the structure and function of PXTs.

Grue, Aden; Grover, Wayne D.

2006-06-01

33

Cross-connect-type wavelength add-drop node with integrated band muxes, interleavers, and monitor  

Microsoft Academic Search

We integrated a cross-connect-type add-drop, de-interleaver, interleaver, combiner, and variable attenuators on one silica waveguide chip and a band demux, band mux, and optical monitor on another to create a potentially low-startup-cost node.

C. R. Doerr; L. W. Stulz; D. S. Levy; M. Cappuzzo; L. Gomez; A. Wong-Foy; E. Chen; G. Richards; R. Pafchek; G. Bogert

2003-01-01

34

Transport performance in optical path cross-connect system employing unequally spaced channel allocation  

Microsoft Academic Search

The transmission performance of an optical path cross-connect (OPXC) system employing unequally spaced channel allocation is evaluated. Four-wave mixing (FWM) light is generated at a different wavelength from all other signal lights when unequally spaced channel allocation is employed in the OPXC system. This evaluation shows that FWM light degrades the transmission performance because the received FWM light power is

Yoshiyuki Hamazumi; Masafumi Koga; Motohaya Ishii; Sen-ichi Suzuki; Ken-ichi Sato

1997-01-01

35

Joint multicasting optical cross-connect employing both space splitters and multi-wavelength converters  

Microsoft Academic Search

As bandwidth-intensive and time-sensitive streams applications such as high-definition television (HDTV) get popular, there rises a demand of supporting multicast communication directly at optical layer on next-generation optical networks. The multicast-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 (space splitters) or multi-wavelength converters (frequency splitters).

Weisheng Hu; Zhaoming Huang; Weiqiang Sun; Yunfeng Peng; Hao He; Yaohui Jin; Yikai Su; Yi Dong; Wei Guo

2006-01-01

36

2 × 2 wavelength- selective cross connect capable of switching 128 channels in sets of eight  

Microsoft Academic Search

We present an efficient 2 × 2 wavelength-selective cross connect that is serviceable without interrupting traffic. It can handle over a hundred channels in a compact fashion by operating on them in sets. The 50-GHz-spaced passbands are flat-topped with no gaps between them, and so it has high cascadability and can exhibit variable-bandwidth switching. It also can multicast. Index Terms-Cross

C. R. Doerr; L. W. Stulz; M. Cappuzzo; L. Gomez; A. Paunsecu; E. Laskowski; S. Chandrasekhar; L. Buhl

2002-01-01

37

Multi-Granular Optical Cross-Connect: Design, Analysis, and Demonstration  

Microsoft Academic Search

A fundamental issue in all-optical switch- ing is to offer efficient and cost-effective transport services for a wide range of bandwidth granularities. This paper presents multi-granular optical cross- connect (MG-OXC) architectures that combine slow (ms regime) and fast (ns regime) switch elements, in order to support optical circuit switching (OCS), op- tical burst switching (OBS), and even optical packet switching

Georgios S. Zervas; Marc De Leenheer; Lida Sadeghioon; Dimitris Klonidis; Yixuan Qin; Reza Nejabati; Dimitra Simeonidou; Chris Develder; Bart Dhoedt; Piet Demeester

2009-01-01

38

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

39

Joint multicasting optical cross-connect employing both space splitters and multi-wavelength converters  

NASA Astrophysics Data System (ADS)

As bandwidth-intensive and time-sensitive streams applications such as high-definition television (HDTV) get popular, there rises a demand of supporting multicast communication directly at optical layer on next-generation optical networks. The multicast-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 (space splitters) or multi-wavelength converters (frequency splitters). The space splitter has no wavelength conversion capability, whereas the frequency splitter has limited fanout, decreased optical signal-to-noise ratio and also is expensive. We therefore proposed a tradeoff architecture called joint multicasting capable optical cross-connect (jMC-OXC) integrating both space splitters and multi-wavelength converters. In this paper, we investigate the network performance and the physical transmission performance on the jMC-OXC architecture by dynamic simulation and experimental demonstration. Three simulation schemes are designed and the results show that the network performance of the jMC-OXCs with limited multi-wavelength converters can obtain a close performance to that with full multi-wavelength converters. A prototype of jMC-OXC is examined and its bit error rate (BER) performance is tested after passing the multi-wavelength converters.

Hu, Weisheng; Huang, Zhaoming; Sun, Weiqiang; Peng, Yunfeng; He, Hao; Jin, Yaohui; Su, Yikai; Dong, Yi; Guo, Wei

2006-10-01

40

Improved method for survivable network design based on pre-cross-connected trails  

NASA Astrophysics Data System (ADS)

Previous work developed the concept of 'pre-cross-connected trails' (PXTs), which are fully pre-connected linear structures of spare capacity used to protect one or more paths end-to-end. To date, the only approach for designing PXT-based restorable networks is a heuristic algorithm suited for the dynamic protection of demands as they arrive in a network. The heuristic can also be used as a 'green fields' planning algorithm for a known set of demands by running through the set and protecting them in order. In both cases, however, recent work has shown that the resulting PXT structures can be looping, as well as long and complex. While the capacity efficiency of the designs was high, the practicality of using such convoluted structures in any real network is doubtful. In this work we propose a semi-heuristic approach based on integer linear programming methods that allows important properties of the PXTs (such as length and degree of looping) to be tightly controlled. We also show how this method may be adapted to the dynamic protection of incrementally arriving random demands. Results show that even when PXTs are restricted to be totally non-looping and of much lower maximum length, we still attain capacity efficiencies near those of the original PXT design heuristic. A notable extra finding is that, in an efficient PXT network design in general, many PXTs are equivalent to standalone 1+1 APS arrangements for certain demand flows.

Grue, Aden; Grover, Wayne D.

2007-02-01

41

Fluorescence monitoring at a recycled water treatment plant and associated dual distribution system – Implications for cross-connection detection  

Microsoft Academic Search

Dual distribution systems are becoming increasingly common in greenfield housing developments in Australia for the redistribution of recycled water to households for non-potable use. Within such schemes there exists the potential for cross-connections between recycled and drinking water systems. Due to the high level of recycled water treatment, these events are unlikely to lead to outbreaks of illness in the

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

2010-01-01

42

Framework for waveband switching in multigranular optical networks: part I-multigranular cross-connect architectures [Invited  

NASA Astrophysics Data System (ADS)

Optical networks using wavelength-division multiplexing (WDM) are the foremost solution to the ever-increasing traffic in the Internet backbone. Rapid advances in WDM technology will enable each fiber to carry hundreds or even a thousand wavelengths (using dense-WDM, or DWDM, and ultra-DWDM) of traffic. This, coupled with worldwide fiber deployment, will bring about a tremendous increase in the size of the optical cross-connects, i.e., the number of ports of the wavelength switching elements. Waveband switching (WBS), wherein wavelengths are grouped into bands and switched as a single entity, can reduce the cost and control complexity of switching nodes by minimizing the port count. This paper presents a detailed study on recent advances and open research issues in WBS networks. In this study, we investigate in detail the architecture for various WBS cross-connects and compare them in terms of the number of ports and complexity and also in terms of how flexible they are in adjusting to dynamic traffic. We outline various techniques for grouping wavelengths into bands for the purpose of WBS and show how traditional wavelength routing is different from waveband routing and why techniques developed for wavelength-routed networks (WRNs) cannot be simply applied to WBS networks. We also outline how traffic grooming of subwavelength traffic can be done in WBS networks. In part II of this study [Cao , submitted to J. Opt. Netw.], we study the effect of wavelength conversion on the performance of WBS networks with reconfigurable MG-OXCs. We present an algorithm for waveband grouping in wavelength-convertible networks and evaluate its performance. We also investigate issues related to survivability in WBS networks and show how waveband and wavelength conversion can be used to recover from failures in WBS networks.

Cao, Xiaojun; Anand, Vishal; Qiao, Chunming

2006-12-01

43

Proposal and demonstration of lambda-based internet exchange (IX) point using GMPLS protocols and photonic cross-connect (PXC)  

NASA Astrophysics Data System (ADS)

This paper proposes an architecture of a next-generation Internet eXchange (IX) based on the Generalized Multi-Protocol Label Switching (GMPLS) technologies and the photonic cross-connect (PXC), hereafter referred to a Lambda-IX. At first, we investigate a basic Lambda-IX model where the PXC provides a GMPLS-controlled lambda label-switched path (LSP) to interconnect different ISPs' border routers. We verify that the proposed Lambda-IX model can achieve the lambda-based and resilient interconnection for the ISPs, thanks to the PXC's bit-rate insensitive operation as well as fast restoration operation. In addition, once GMPLS functionalities are introduced on the border routers as well as the PXC, very flexible interconnection can be achieved such as demand-based creation and deletion of lambda LSPs. Next, we initiatively demonstrate an experimental Lambda-IX using a PXC and IP/MPLS routers. A Lambda-LSP with OC-192 bandwidth can be successfully created by using the GMPLS RSVP-TE signaling protocol via a control plane, and an EGP session of Border Gateway Protocol 4 (BGP-4) can be established over the Lambda-LSP created between the GMPLS-enabled border routers via a data plane. We also evaluate the fault recovery operation in the case where such Lambda-IXs are consisted of several PXCs and demonstrate that the Lambda-LSP as well as the corresponding BGP session can be restored with a fast recovery time of less than 1s. Through these investigation and demonstration, it is revealed that the Lambda-IX can be put to practical use aiming at inter-exchanging a large traffic in a near future, while enriching the functions of IX.

Tsuritani, Takehiro; Okamoto, Shuichi; Ogino, Nagao; Otani, Tomohiro; Tanaka, Hideaki

2004-10-01

44

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 ...

45

Nonblocking all-optical cross connect based on regenerative all-optical wavelength converter in a transparent demonstration over 42 nodes and 16800 km  

Microsoft Academic Search

A red-shift optical filter all-optical wavelength converter compatible to all-optical WDM networks is introduced and demonstrated at 40 and 10 Gb\\/s. The wavelength converter provides reshaping and can act as a power equalizer. We use the device to overcome wavelength blocking in a looped-fiber network demonstration equivalent to 42 cross-connect switches and a 16800 km transmission distance.

Juerg Leuthold; Roland Ryf; Drew N. Maywar; Steven Cabot; James Jaques; S. S. Patel

2003-01-01

46

A tunable wavelength-interchanging cross-connect scheme utilizing two periodically poled LiNbO 3 waveguides with double-pass configuration  

Microsoft Academic Search

A tunable wavelength-interchanging cross-connect (WIXC) scheme is proposed by utilizing two periodically poled LiNbO3 waveguides. A fiber Brag grating is utilized to link the two waveguides so as to configurate the double-pass operation. In each waveguide, sum frequency generation (SFG) and difference frequency generation (DFG) take place during the forward propagation and backward propagation, respectively. The two tunable pumps, utilized

Song Yu; Y. J. Zhang; Hua Zhang; Wanyi Gu

2007-01-01

47

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

48

Optimization of Passive and Hybrid Mode-locked Figure Eight Laser  

NASA Astrophysics Data System (ADS)

In pulsed fiber laser using Q-switching or mode locking techniques, the choice of the different components and the management of linear and non linear parameters of the cavity, play a paramount role in the generation of stable ultra short pulses with high peak powers and low widths. In this paper, we focus on the operating process of mode locked fiber lasers especially passively and hybrid type Eight Fiber Lasers (8FLs). By modeling the light propagation within the two cavities, we describe the whole operating process of ultra short pulses generation. The interaction between the mode locking mechanism and nonlinear effects in fiber laser is also illustrated. We demonstrate enhancing non linear effects do not lead necessarily to better results. It depends on the type of mode locking techniques used. The highest and narrowest output pulses are obtained for specific values of the non linear parameters and the mean dispersion of the cavity.

Ennejah, Tarek; Bahloul, Faouzi; Salhi, Mohamed; Attia, Rabah

2013-09-01

49

THE FRACTURED FIGURE EIGHT: EXPLORING THE RELATIONSHIP BETWEEN SOCIAL AND PERSONAL KNOWLEDGE  

Microsoft Academic Search

This paper reviews current critiques of Kolb's experiential learning theory. Critiques converge on the belief that the theory places undo emphasis on the role of individual experience at the expense of social, political, and cultural elements of learning. This paper suggests that such critiques are based on a limited, selective, or simplistic reading of the initial theory. The theoretical relationship

D. Christopher Kayes

50

Cross-Connections of Chemistry  

NASA Astrophysics Data System (ADS)

We are in desperate need of qualified chemistry teachers. Are the teachers who have biology, physics, or some psychology degrees qualified to teach chemistry? Have they taken enough chemistry to be prepared to teach outside their degree field? If remediation is necessary, what courses should be required? Attracting pre-service science teachers to the study of pure chemistry is not an easy task when more attractive course offerings are available. Maybe we should concentrate on cross-training in-service teachers by providing appropriate graduate courses to encourage them and bring them into the family. Many teachers with degrees outside the traditional discipline of chemistry have adequate backgrounds in the applications of chemistry. Requiring hours of undergraduate education before they enter the hallowed halls of the chemistry building as graduate students only serves to discourage a large segment of in-service teachers who wish to broaden their perspective. The National Science Education Standards make a compelling argument for connecting and integrating science courses for practicing teachers (3). We are at the crossroads. At a time when we so desperately need qualified chemistry teachers, shouldn't we be more open in our graduate teaching programs, inviting those with degrees in other disciplines to start on a graduate degree without insisting on undergraduate or survey coursework first? Many potential chemical education graduate students have a background in chemistry--it is just known by another name.

Mason, Diana S.

2002-02-01

51

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

52

Cross-Connections: Causes, Consequences, and Cures.  

National Technical Information Service (NTIS)

The physical principles involved in interconnecting two plumbing systems operating at different pressures were elucidated many years ago by the earliest students of hydraulics. It is obvious that water, or any other fluid, will flow from a point of higher...

W. M. Dunne C. W. Christenson

1977-01-01

53

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

54

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

DOEpatents

A propulsion and stabilization system comprising a series of FIG. 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 FIG. 8 coils either longitudinally and/or vertically with resulting changes in the propulsion, the vertical stability, and the suspension.

Rote, Donald M. (Lagrange, IL); He, Jianliang (Woodridge, IL); Johnson, Larry R. (Naperville, IL)

1994-01-01

55

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

56

Silica-waveguide 1 × 9 wavelength-selective cross connect  

Microsoft Academic Search

We present an integrated-optics device that switches any of eight wavelengths from one input fiber to any of nine output fibers with <7 dB loss. Its features are suitable for mass production: use of standard silica waveguides, double-rejection switching and filtering for all paths, and compactness.

C. R. Doerr; L. W. Stulz; D. S. Levy; M. Cappuzzo; E. Chen; L. Gomez; E. Laskowski; A. Wong-Foy; T. Murphy

2002-01-01

57

Tutorial: waveguide-based optical cross-connect switches  

Microsoft Academic Search

Photonic switch arrays utilizing waveguide devices address numerous wavelength division multiplexing applications. They possess several advantages, including small size, permanent optical alignment, insensitivity to vibration and straightforward integration. Switches based on optical interference, total internal reflection and amplification will be discussed, with emphasis on devices that change state on the millisecond time scale.

J. E. Fouquet

2002-01-01

58

Analysis of dual-microring-resonator cross-connect switches and modulators.  

PubMed

Modeling and simulation results on new, resonant, waveguided 2 x 2 switches and 1 x 1 modulators are presented here. The devices employ two coupled microrings: one fixed and one floating. The fixed ring is coupled to bus waveguides that are crossed or are locally parallel. Electrooptic and thermooptic switching at lambda = 1.55 mum are investigated. A novel peaks-and-valley spectral response allows low-power switching with low crosstalk and low insertion loss. Complete switching is attained when the complex index of both rings is perturbed by Deltan ~ 4 x 10-4. The modulator's optical output power is a linear function of Deltan over three to five decades of Deltan. PMID:19498812

Emelett, Stephen; Soref, Richard

2005-10-01

59

Cascaded active silicon microresonator array cross-connect circuits for WDM networks-on-chip  

Microsoft Academic Search

We propose a design of an optical switch on a silicon chip comprising a 5 × 5 array of cascaded waveguide-crossing-coupled microring resonator-based switches for photonic networks-on-chip applications. We adopt our recently demonstrated design of multimode-interference (MMI)-based wire waveguide crossings, instead of conventional plain waveguide crossings, for the merits of low loss and low crosstalk. The microring resonator is integrated

Andrew W. Poon; Fang Xu; Xianshu Luo

2008-01-01

60

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

61

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

62

Comparison of Wavelength-Interchanging and Wavelength-Selective Cross-Connects in Multiwavelength All-Optical Networks  

Microsoft Academic Search

We quantify the benefits of wavelength interchanging in terms of the required capacity and the blocking probability. Most of the previous work on this subject assumed single-fiber links; we study networks with multiple fibers, extend Barry's (see Proceedings of IEEE INFOCOM '95, vol.2, p.402, 1995) probability analysis to the multifiber case, and compare those results with fiber gain calculations in

Gibong Jeong; Ender Ayanoglu

1996-01-01

63

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

64

U.S. EPA's Manual of Practice for the Investigation and Control of Cross-Connection Pollution into Storm Drainage Systems.  

National Technical Information Service (NTIS)

Dry-weather flows discharging from storm drainage systems can contribute significant pollutant loadings to receiving waters. If these loadings are ignored, little improvement in receiving water conditions may occur with many stormwater control programs. T...

R. E. Pitt R. Field

1992-01-01

65

77 FR 5185 - Drawbridge Operation Regulation; Atlantic Intracoastal Waterway Albermarle Sound to Sunset Beach...  

Federal Register 2010, 2011, 2012, 2013

...governing the operation of the Figure Eight Swing Bridge across the Atlantic Intracoastal...who owns and operates the Figure Eight Swing Bridge across the Atlantic Intracoastal...on the hour and half hour. Figure Eight Swing Bridge, at AIWW mile 278.1,...

2012-02-02

66

Protection against the freezing of solar collectors  

Microsoft Academic Search

A solar heat collector has a transparent cover and metal fins beneath the cover. Secured to each fin is a tube through which flows water to be heated, the tube having the general cross sectional configuration of a figure eight and the tube being welded to the fin at one end of the major axis of the figure eight. Round

L. Besse; F. Durand

1982-01-01

67

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

68

75 FR 36608 - Drawbridge Operation Regulation; Atlantic Intracoastal Waterway, (AIWW) Scotts Hill, NC  

Federal Register 2010, 2011, 2012, 2013

...governed the operation of the Figure Eight Swing Bridge, at AIWW mile 278.1, at Scotts...who owns and operates the Figure Eight Swing Bridge, had requested a change to the...for both roadway and waterway users. The swing bridge provides the only route on and...

2010-06-28

69

Effect of flapping trajectories on the dragonfly aerodynamics  

Microsoft Academic Search

The effects of translational, figure-eight and double-figure-eight flapping trajectories on the dragonfly aerodynamics were\\u000a numerically studied by solving the Navier-Stokes equations. There is a common characteristic regarding the lift\\/drag force\\u000a coefficients that the downstroke flapping provides the lift forces while the upstroke flapping creates the thrust forces for\\u000a different flapping trajectories. The maximum lift force coefficient exceeds five for the

Jinliang Xu; Chuangxin Zhao; Yongli Zhang; Yang Zhang

2006-01-01

70

TRIMETHYLTIN-INDUCED HYPERACTIVITY: TIME COURSE AND PATTERN  

EPA Science Inventory

Adult male Long-Evans rats were intubated with either 0,5,6, or 7 mg/kg trimethyltin chloride. Activity was measured for 1 hr in a figure-eight maze 2 hr after dosing (day 0) and again on days 4,8,16 and 32 after dosing. On days 49-51, activity was measured in a figure-eight maze...

71

Coriolis effects in the dynamics of a rotating elastic structure  

Microsoft Academic Search

Summary Small oscillations of a rotating elasticum with a mass at the free end are investigated with Poincaré-Lindstedt series. It is shown that the mass moves on a figure-eight shaped curve in a direction determined by the sign of the angular velocity and hence that the Coriolis force influences the motion.

M. Brøns; P. G. Hjorth; W. Kliem

1996-01-01

72

Light-oriented swimming of schooling fish in continuous channels  

Microsoft Academic Search

Synopsis Fish groups were tested both in a circular and in a figure eight-shaped channel. In both cases fish showed a long lasting, constant direction swimming provided that illumination was maintained at a constant angle around the channel. In the circular channel, fish did not reverse direction, as would be expected, when light angle was shifted from one side to

Luis E. Levin; Ricardo Salazar; Pedro Belmonte; Aldernaro Romero

1989-01-01

73

Twisted structure of a cyclic hexapeptide containing a combination of alternating L-Leu-D-Leu-Aib segments.  

PubMed

We designed and synthesized a C(2)-symmetric cyclic hexapeptide, cyclo(L-Leu-D-Leu-Aib)(2) (2), which contains L- and D-amino acids and achiral Aib residues. The conformation of 2 was analyzed in the crystalline state and in solution, which was a unique figure-eight-shaped conformation. PMID:23006337

Demizu, Yosuke; Nagoya, Saori; Doi, Mitsunobu; Sato, Yukiko; Tanaka, Masakazu; Kurihara, Masaaki

2012-10-03

74

A gestural instruction learning robot using information infrastructure  

Microsoft Academic Search

This paper proposes a gestural instruction learning algorithm for robots which move in response to video information. Applying the algorithm to an actual moving robot in a trajectory learning experiment confirms that it enables a robot to understand, on the same level that a dog might, both the meaning of a human macro sign (i.e. a figure-eight sign) and the

T. Yamaguchi; N. Kanazawa; K. Akita; M. Yoshihara

1995-01-01

75

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

76

Wellness Programs: Preventive Medicine to Reduce Health Care Costs.  

ERIC Educational Resources Information Center

A wellness program is a formalized approach to preventive health care that can positively affect employee lifestyle and reduce future health-care costs. Describes programs for health education, smoking cessation, early detection, employee assistance, and fitness, citing industry success figures. (eight references) (MLF)

Martini, Gilbert R., Jr.

1991-01-01

77

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...

78

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

79

Effects of wavelength routing and selection algorithms on wavelength conversion gain in WDM optical networks  

Microsoft Academic Search

Wavelength division multiplexing technology is emerging as the transmission and switch- ing mechanism for future optical mesh networks. In these networks, it is desired that a wavelength can be routed without electrical conversions. Two technologies are possible for this purpose: Wavelength Selective Cross-Connects (WSXC), and Wavelength Interchanging Cross-Connects (WIXC) which involve wavelength conversion. It is believed that wavelength converters may

Ezhan Karasan; Ender Ayanoglu

1998-01-01

80

Random photonic crystal optical memory  

NASA Astrophysics Data System (ADS)

Currently, optical cross-connects working on wavelength division multiplexing systems are based on optical fiber delay lines buffering. We designed and analyzed a novel photonic crystal optical memory, which replaces the fiber delay lines of the current optical cross-connect buffer. Optical buffering systems based on random photonic crystal optical memory have similar behavior to the electronic buffering systems based on electronic RAM memory. In this paper, we show that OXCs working with optical buffering based on random photonic crystal optical memories provides better performance than the current optical cross-connects.

Wirth Lima, A., Jr.; Sombra, A. S. B.

2012-10-01

81

Improving the Quality of Protein Crystals Using Stirring Crystallization  

NASA Astrophysics Data System (ADS)

Recent reports state that a high magnetic field improves the crystal quality of bovine adenosine deaminase (ADA) with an inhibitor [Kinoshita et al.: Acta Cryst. D59 (2003) 1333]. In this paper, we examine the effect of stirring solution on ADA crystallization using a vapor-diffusion technique with rotary and figure-eight motion shakers. The probability of obtaining high-quality crystals is increased with stirring in a figure-eight pattern. Furthermore, rotary stirring greatly increased the probability of obtaining high-quality crystals, however, nucleation time was also increased. The crystal structure with the inhibitor was determined at a high resolution using a crystal obtained from a stirred solution. These results indicate that stirring with simple equipment is as useful as the high magnetic field technique for protein crystallization.

Adachi, Hiroaki; Matsumura, Hiroyoshi; Niino, Ai; Takano, Kazufumi; Kinoshita, Takayoshi; Warizaya, Masaichi; Inoue, Tsuyoshi; Mori, Yusuke; Sasaki, Takatomo

2004-04-01

82

Lichen sclerosus in a breast cancer survivor on an aromatase inhibitor: a case report.  

PubMed

Lichen sclerosus is a commonly misdiagnosed disease that is characterized by thinned, hypopigmented, crinkled skin that often forms a figure-eight shape around the vaginal and anal openings. We present a case of advanced lichen sclerosus in a 53-year-old female patient prescribed a nonsteroidal aromatase inhibitor after the excision of a breast cancer tumor. We present a diagnostic approach to lichen sclerosus by recognizing its common figure-eight pattern, and we review the known causes and treatment of lichen sclerosus. Research has shown that lichen sclerosus is more common in low estrogen states, and thus it is logical that aromatase inhibitors could increase a patient's risk for developing this disease. We therefore propose that all patients prescribed aromatase inhibitors undergo regular vulvo-vaginal exams to rule out lichen sclerosus and other hypoestrogen-related vulvo-vaginal problems. PMID:22956445

Potter, Jennifer E; Moore, Kendra A

2012-09-07

83

Dragonfly (Sympetrum flaveolum) flight: Kinematic measurement and modelling  

NASA Astrophysics Data System (ADS)

The kinematics of the flapping hindwing of the dragonfly Sympetrum flaveolum is investigated. Several tracking points along the leading edge and trailing edge of the hindwing are recorded and studied using high-speed videography. By applying more tracking points along the leading edge around the nodus, it is shown that the leading edge is not one rigid piece, but two pieces hinged at the nodus with physical constraint of forty degrees. Such arrangement also eases the difficulties in rotating the wing during pronation by bending the leading edge forward and flattening the wing. From the kinematic experiments, two flapping patterns of the dragonfly wing are revealed as a simple figure-eight and a double figure-eight flapping pattern. Kinematic modelling of the two flapping patterns is then established by transforming the flapping motions into angular rotations about the pivoting wing root in a local body-fixed spherical coordinate system.

Chen, Y. H.; Skote, M.; Zhao, Y.; Huang, W. M.

2013-07-01

84

A symplectic integrator for the symmetry reduced and regularised planar 3-body problem with vanishing angular momentum  

NASA Astrophysics Data System (ADS)

We construct an explicit reversible symplectic integrator for the planar 3-body problem with zero angular momentum. We start with a Hamiltonian of the planar 3-body problem that is globally regularised and fully symmetry reduced. This Hamiltonian is a sum of 10 polynomials each of which can be integrated exactly, and hence a symplectic integrator is constructed. The performance of the integrator is examined with three numerical examples: The figure eight, the Pythagorean orbit, and a periodic collision orbit.

Rose, Danya; Dullin, Holger R.

2013-10-01

85

Strength and ductility of asphalts  

Microsoft Academic Search

This article presents data on the ductility of asphalt as measured in an RMI-5 tensile tester, which is designed for tests on raw and vulcanized rubbers and rubber mixes. The asphalt test specimens were prepared in the form of ''figure eights'' and the tests were performed at 23-24°C. Discrete load levels were determined at each 25-50% elongation. The true stress

A. F. Frolov; A. N. Aminov; V. V. Egorova; V. N. Ovchinnikova

1984-01-01

86

A symplectic integrator for the symmetry reduced and regularised planar 3-body problem with vanishing angular momentum  

NASA Astrophysics Data System (ADS)

We construct an explicit reversible symplectic integrator for the planar 3-body problem with zero angular momentum. We start with a Hamiltonian of the planar 3-body problem that is globally regularised and fully symmetry reduced. This Hamiltonian is a sum of 10 polynomials each of which can be integrated exactly, and hence a symplectic integrator is constructed. The performance of the integrator is examined with three numerical examples: The figure eight, the Pythagorean orbit, and a periodic collision orbit.

Rose, Danya; Dullin, Holger R.

2013-07-01

87

Tightening the Knot in Phytochrome by Single-Molecule Atomic Force Microscopy  

Microsoft Academic Search

A growing number of proteins have been shown to adopt knotted folds. Yet the biological roles and biophysical properties of these knots remain poorly understood. We used protein engineering and atomic force microscopy to explore the single-molecule mechanics of the figure-eight knot in the chromophore-binding domain of the red\\/far-red photoreceptor, phytochrome. Under load, apo phytochrome unfolds at forces of ?47

Thomas Bornschlögl; David M. Anstrom; Elisabeth Mey; Joachim Dzubiella; Matthias Rief; Katrina T. Forest

2009-01-01

88

46 CFR 56.20-15 - Valves employing resilient material.  

Code of Federal Regulations, 2012 CFR

...Category A valves are required in the following locations: (i) Valves at vital piping system manifolds; (ii) Isolation valves in cross-connects between two piping systems, at least one of which is a vital system, where failure of the...

2012-10-01

89

BECKETT AND SYNAESTHESIA  

Microsoft Academic Search

Synaesthesia, the cross-connection of the different senses like colour hearing, was an important element in Western art and literature around the beginning of the twentieth century. The delirium of the senses that Rimbaud's sonnet \\

Yoshiki Tajiri

2001-01-01

90

77 FR 50743 - Self-Regulatory Organizations; NYSE Arca, Inc.; Order Approving a Proposed Rule Change Amending...  

Federal Register 2010, 2011, 2012, 2013

...that would otherwise be applicable. LCN CSP Connections A User may act as a content service provider (a ``CSP User'') and deliver services to another...either via direct cross connect between the CSP User and Subscribing Users; or in...

2012-08-22

91

77 FR 50742 - Self-Regulatory Organizations; New York Stock Exchange LLC; Order Approving a Proposed Rule...  

Federal Register 2010, 2011, 2012, 2013

...that would otherwise be applicable. LCN CSP Connections A User may act as a content service provider (a ``CSP User'') and deliver services to another...either via direct cross connect between the CSP User and Subscribing Users; or in...

2012-08-22

92

77 FR 50733 - Self-Regulatory Organizations; NYSE MKT LLC; Order Approving a Proposed Rule Change Amending the...  

Federal Register 2010, 2011, 2012, 2013

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2012-08-22

93

77 FR 50746 - Self-Regulatory Organizations; NYSE Arca, Inc.; Order Approving a Proposed Rule Change Amending...  

Federal Register 2010, 2011, 2012, 2013

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2012-08-22

94

77 FR 50734 - Self-Regulatory Organizations; NYSE MKT LLC; Order Approving a Proposed Rule Change Amending the...  

Federal Register 2010, 2011, 2012, 2013

...that would otherwise be applicable. LCN CSP Connections A User may act as a content service provider (a ``CSP User'') and deliver services to another...either via direct cross connect between the CSP User and Subscribing Users; or in...

2012-08-22

95

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

96

Delay Analysis of All-Optical Packet-Switching Ring and Bus Communications Networks  

Microsoft Academic Search

We study the delay performance of all-optical packet communication networks configured as ring and bus topologies employing cross-connect switches (or wavelength routers). Under a cross-connect network implementation, a packet experiences no (or minimal) internal queueing delays. Thus, the network can be implemented by high speed all-optical components. We further assume a packet-switched network operation, such as that using a slotted

Izhak Rubin; Jing Ling

2001-01-01

97

Hybrid hierarchical optical path network design algorithm with 2-stage ILP optimization  

NASA Astrophysics Data System (ADS)

We propose a 2-stage ILP-based design algorithm for hierarchical optical path networks that utilize hybrid-HOXCs. The hybrid-HOXC consists of an optical waveband cross-connect and an electrical cross-connect which grooms only wavelength paths. Its effectiveness is evaluated through numerical experiments. Impact of electrical/optical port cost ratio on the total network cost is also investigated.

Le, Hai-Chau; Hasegawa, Hiroshi; Sato, Ken-Ichi

2010-12-01

98

Project W-320 high vacuum 241-AY-102 annulus ventilation system operability test report  

SciTech Connect

This report documents the test results of OTP-320-001, Tank 241-AY-102 Annulus Ventilation System Testing. Included in the appendices are: (1) Supporting documentation prepared to demonstrate the structural integrity of the tank at high annulus vacuum (<20 INWG), and (2) a report that identifies potential cross connections between the primary and annulus ventilation systems. These cross connections were verified to be eliminated prior to the start of testing.

Bailey, J.W.

1998-03-12

99

Neurobehavioral toxicology of pyrethroid insecticides  

SciTech Connect

Pyrethroid insecticides are classified as either Type I or Type II based upon in vivo toxic signs, and neurophysiological and biochemical data. Both axonal sodium channels and the ..gamma..-aminobutyric acid (GABA) receptor complex have been proposed as the major site of action of the Type II pyrethroids. This investigation characterized the behavior and biochemical effects of low dosages of pyrethroids in rats. Type I and II pyrethroids were tested for effects on figure-eight maze activity and the acoustic startle response (ASR). All compounds decreased figure-eight maze activity. Interactions of Type I and II pyrethroids with the three major binding sites on the GABA complex were determined in vivo. Radioligand binding experiments assessed in vitro interactions of pyrethroids with the three major GABA-complex binding sites. None of the pyrethroids competed for (/sup 3/H)-muscimol or (/sup 3/H)-flunitrazepam binding. Only Type II pyrethroids inhibited binding of (/sup 35/S)-t-butylbicyclophosphorothionate (TBPS) in cortical synaptosome preparations with K/sub i/ values of 5 to 10 ..mu..M. The (/sup 35/S)-TBPS data implicate the TBPS/picrotoxinin binding site in the mechanism of Type II pyrethroid toxicity. The results of these experiments support the classification of pyrethroids into two classes, and demonstrate the utility of the figure-eight maze and the ASR in studies to elucidate neurotoxic mechanisms. The interaction of the Type II pyrethroids is probably restricted to the TBPS/picrotoxinin binding domain on the GABA complex as shown by both the in vivo and in vitro studies.

Crofton, K.M.

1986-01-01

100

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

101

SPECIAL ISSUE DEVOTED TO THE 25th ANNIVERSARY OF THE A.M. PROKHOROV GENERAL PHYSICS INSTITUTE: Relativistic motion and radiation of an electron in the field of an intense laser pulse  

NASA Astrophysics Data System (ADS)

The motion of an electron in the fields of relativistic-intensity linearly and circularly polarised laser radiation is analysed. The analysis is based on the numerical solution of the Newton equation with the Lorentz force. The electromagnetic radiation of an electron interacting with a laser pulse is studied. It is shown that this radiation is emitted in the form of extremely short attosecond pulses. It is found that an initially immobile electron does not move along figure-eight trajectories in the field of a linearly polarised laser pulse.

Galkin, A. L.; Korobkin, V. V.; Romanovskii, M. Yu; Shiryaev, O. B.

2007-10-01

102

The Analemma  

NSDL National Science Digital Library

This site by Joh 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 sunâs 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.

2006-07-13

103

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

104

Dialysis Purification of Integrase-DNA Complexes Provides High-Resolution Atomic Force Microscopy Images: Dimeric Recombinant HIV-1 Integrase Binding and Specific Looping on DNA  

PubMed Central

It remains difficult to obtain high-resolution atomic force microscopy images of HIV-1 integrase bound to DNA in a dimeric or tetrameric fashion. We therefore constructed specific target DNAs to assess HIV-1 integrase binding and purified the complex by dialysis prior to analysis. Our resulting atomic force microscopy analyses indicated precise size of binding human immunodeficiency virus type 1 (HIV-1) recombinant integrase in a tetrameric manner, inducing formation of a loop-like or figure-eight-like secondary structure in the target DNA. Our findings regarding the target DNA secondary structure provide new insights into the intermediate states of retroviral integration.

Ohmori, Rei; Ozeki, Munetaka; Tamaki, Keiji; Yoshikawa, Kenichi

2013-01-01

105

The Effects of Two Adhesive Ankle-Taping Methods on Strength, Power, and Range of Motion in Female Athletes  

PubMed Central

Background Taping is a ubiquitous strategy to help prevent ankle sprains. The restrictive qualities of various taping methods may impair athletic performance. Objective The objective of the study was to compare the Gibney closed basket weave taping method with heel-locks to heel-locks and figure-eights in order to determine their effect on vertical jump performance and active range of motion (ROM) before and after exercise. Methods Eleven female varsity basketball athletes were subjected to three conditions of no ankle support (control), heel-locks, and figure-eights. The dependent variables of ankle active ROM, plantarflexor maximum voluntary contraction and jump height for the countermovement jump (CMJ), drop jump (DJ), and concentric only squat jump (COSJ) were randomly ordered. Following taping or control conditions, participants were pre-tested, completed a ten-minute treadmill run at 9.6 km/hr with a 3 minute cool down and then repeated the testing procedures. Results There were no significant differences in jump performance between taping methods or the effect of exercise. However significant differences for pre-/post-exercise for plantarflexor (p < 0.0001) and dorsiflexor (p = 0.007) active ROM and between no support and taping for plan-tarflexor ROM (p = 0.004) was found. Conclusions Despite plantarflexor active ROM being restricted by both taping procedures compared to the control, no effect on jump performance occurred.

Quackenbush, Katherine E.; Barker, Paula R.J.; Stone Fury, Shauna M.

2008-01-01

106

Path integration: effect of curved path complexity and sensory system on blindfolded walking.  

PubMed

Path integration refers to the ability to integrate continuous information of the direction and distance traveled by the system relative to the origin. Previous studies have investigated path integration through blindfolded walking along simple paths such as straight line and triangles. However, limited knowledge exists regarding the role of path complexity in path integration. Moreover, little is known about how information from different sensory input systems (like vision and proprioception) contributes to accurate path integration. The purpose of the current study was to investigate how sensory information and curved path complexity affect path integration. Forty blindfolded participants had to accurately reproduce a curved path and return to the origin. They were divided into four groups that differed in the curved path, circle (simple) or figure-eight (complex), and received either visual (previously seen) or proprioceptive (previously guided) information about the path before they reproduced it. The dependent variables used were average trajectory error, walking speed, and distance traveled. The results indicated that (a) both groups that walked on a circular path and both groups that received visual information produced greater accuracy in reproducing the path. Moreover, the performance of the group that received proprioceptive information and later walked on a figure-eight path was less accurate than their corresponding circular group. The groups that had the visual information also walked faster compared to the group that had proprioceptive information. Results of the current study highlight the roles of different sensory inputs while performing blindfolded walking for path integration. PMID:22840893

Koutakis, Panagiotis; Mukherjee, Mukul; Vallabhajosula, Srikant; Blanke, Daniel J; Stergiou, Nicholas

2012-07-27

107

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

Microsoft Academic Search

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

Seong-Soon Joo; Byung-Ho Yae; Jong-Hyun Lee

2002-01-01

108

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

109

Framework for waveband switching in multigranular optical networks: part II--wavelength/waveband conversion and survivability [Invited  

NASA Astrophysics Data System (ADS)

We consider multigranular optical networks using waveband switching (WBS) technology. The use of advanced WDM has significantly increased the available bandwidth in backbone networks by increasing the number of wavelengths. As the number of wavelengths in a fiber is increased, the number of ports or the size of the optical cross connects increases rapidly. Using WBS, wavelengths are grouped into bands and switched as a single entity thus reducing the cost and control complexity of switching nodes by minimizing the port count. Part I of our study [J. Opt. Netw.5, 1043-1055 (2006)] compared the various cross-connect architectures for WBS including the three-layer and single-layer multigranular cross connects. It also discussed various issues relating to waveband switching networks that are different from traditional wavelength routing networks (WRNs), for example, traffic grooming, and it showed why techniques developed for WRNs cannot be simply applied to WBS networks. We study the effect of wavelength and waveband conversion on the performance of WBS networks with reconfigurable multigranular optical cross connects. We present an algorithm for waveband grouping in wavelength convertible networks and evaluate its performance with full, limited, and intraband wavelength conversion. We then focus on survivability in WBS networks and show how waveband and wavelength conversion can be used effectively to recover from failures in WBS networks.

Cao, Xiaojun; Anand, Vishal; Qiao, Chunming

2007-01-01

110

76 FR 76463 - Self-Regulatory Organizations; International Securities Exchange, LLC; Notice of Filing and...  

Federal Register 2010, 2011, 2012, 2013

...third-party managed service providers. The Exchange, therefore...reference to Managed Service Provider from its Schedule of fees also...Ethernet/Managed Service Provider connection costs are identified...members to cross- connect their servers to ISE servers, we...

2011-12-07

111

Dissolved Organic Matter Dynamics in two Suburban Catchments in NE England  

Microsoft Academic Search

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

A. Baker; E. Simpson; C. Bryant

2005-01-01

112

Network Effects, Congestion Externalities, and Air Traffic Delays: Or Why All Delays Are Not Evil  

Microsoft Academic Search

We examine two factors that might explain the extent of air traffic delays in the United States: network benefits due to hubbing and congestion externalities. Airline hubs enable passengers to cross-connect to many destinations, thus creating network benefits that increase in the number of markets served from the hub. Delays are the equilibrium outcome of a hub airline equating high

Christopher Mayer; Todd Sinai

2002-01-01

113

Integrated Network Design Tools (INDT): a suite of network design tools for current and next generation networking technologies  

Microsoft Academic Search

Integrated Network Design Tools (INDT) is a suite of tools being developed at Bell Labs. This suite of tools is built on a flexible software architecture based on C++ and can provide optimal network design for a mix of private line, switched voice and switched multimedia services using a mix of circuit and ATM switches and cross connects and facilities

B. T. Doshi; C. A. Funka-Lea; P. Harshavardhana; J. Gong; R. Nagarajan; S. Ravikumar; S. Chen; Y. Wang

1997-01-01

114

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.

115

OXADMs: The next generation of optical switching devices  

Microsoft Academic Search

This paper introduces a new optical device model named as an optical cross add and drop multiplexer (OXADM) which has potential use in CWDM metro area networks. The device uses the concepts of combination of optical add\\/drop multiplexing and optical cross connect between two main transmission lines in order to implement the wavelength routing operation [10]. MEMS optical switches are

Mohammad Syuhaimi Ab-Rahman; A. A. A. Rahni; Mohd Saiful Dzulkefly Zan; Kasmiran Jumari; Sahbudin Shaari; Mohd Faisal Ibrahim

2008-01-01

116

Survivability schemes in optical cross add and drop multiplexer  

Microsoft Academic Search

Optical cross add drop multiplexer (OXADM) is a newly invented device in optical networks. It is designed with a combined concept of optical cross connect (OXC) and optical add drop multiplexer (OADM) which is potentially used to increase efficiency and flexibility of optical network particularly in metropolitan ring and mesh configuration. The OXADM node focuses on providing functionalities of transport,

M. S. Ab-Rahman

2008-01-01

117

OXADM restoration schemes in CWDM metropolitan ring network  

Microsoft Academic Search

We demonstrate a newly invented device named as optical cross add and drop multiplexer (OXADM) which designed with a combined concept of optical cross connect (OXC) and optical add drop multilexer (OADM). It is designed by improving all drawbacks appear in the previous device with some interesting features added. The OXADM node focuses on providing functionalities of transport, multiplexing, routing,

M. S. Ab-Rahman; M. T. M. Yusof

2008-01-01

118

Large-channel-count WDM control devices  

Microsoft Academic Search

There now exist commercial wavelength-division multiplexing (WDM) systems with at least 80 wavelengths. There are many approaches to designing optical control devices, such as wavelength add-drops, wavelength selective cross connects, and dynamic equalizers, to handle so many channels. One approach is to use devices that act on only one or a few channels at a time and leave the other

C. R. Doerr

2000-01-01

119

Cleantech and an Analysis of the Platform Nature of Life Sciences: Further Reflections upon Platform Policies  

Microsoft Academic Search

Most articles about life sciences begin from healthcare. This article reaches healthcare by an unusual route. It begins by trying to map out the complex content of the “Cleantech” platform. It then cross-connects important parts of that to the Agro-food industry, only finally relating important aspects of that to Healthcare biosciences. By Cleantech is meant the complex of industry activities

Philip Cooke

2008-01-01

120

Single sided stereo angle silicon strip detector  

SciTech Connect

A new two dimensional single sided silicon strip detector using cross connected short strips interleaved with long strips has been designed. In the design the z coordinate (along the strips) can be measured by finding the crossing point of the strips. No sacrifice is necessary on the r[var phi] coordinate resolution in the design.

Huhtinen, M.; Orava, R.; Pimiae, M.; Tuuva, T.; Yloestalo, J.; Oesterberg, K. (SEFT, Helsinki (Finland). Research Inst. for High Energy Physics); Eraenen, S.; Leinonen, K. (VTT, Espoo (Finland). Technical Research Centre of Finland); Hietanen, I. (Detection Technology Inc., Espoo (Finland)); Turchetta, R.; Schaeffer, M. (LEPSI, Strasbourg (France))

1993-08-01

121

46 CFR 78.17-5 - Valves and closing appliances.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Valves and closing appliances. 78.17-5...Drills, and Inspections § 78.17-5 Valves and closing appliances. (a) It shall be the duty of the master to see that all valves, including cross connecting...

2012-10-01

122

Black hole formation from a null fluid in extended Palatini gravity  

NASA Astrophysics Data System (ADS)

We study the formation and perturbation of black holes by null fluxes of neutral matter in a quadratic extension of general relativity formulated à la Palatini. Working in a spherically symmetric space-time, we obtain an exact analytical solution for the metric that extends the usual Vaidya-type solution to this type of theory. We find that the resulting space-time is formally that of a Reissner-Nordström black hole but with an effective charge term carrying the wrong sign in front of it. This effective charge is directly related to the luminosity function of the radiation stream. When the ingoing flux vanishes, the charge term disappears and the space-time relaxes to that of a Schwarzschild black hole. We provide two examples that illustrate the formation of a black hole from Minkowski space and the perturbation by a finite pulse of radiation of an existing Schwarzschild black hole.

Martinez-Asencio, Jesus; Olmo, Gonzalo J.; Rubiera-Garcia, D.

2012-11-01

123

Comparison of major parameters in electrodynamic and electromagnetic levitation transport systems. Final report, July 1991-September 1992  

SciTech Connect

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

124

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

125

Magnetic resonance imaging of time-varying magnetic fields from therapeutic devices.  

PubMed

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 and radiofrequency hyperthermia probes. A method to image such time-varying magnetic fields is introduced in this study. 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 was able to reconstruct the three-dimensional components of the oscillating magnetic field vector. PMID:23355446

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

2013-01-28

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

Special colored superpolynomials and their representation-dependence  

NASA Astrophysics Data System (ADS)

We introduce the notion of "special superpolynomials" by putting q = 1 in the formulas for reduced superpolynomials. In this way we obtain a generalization of special HOMFLY polynomials depending on one extra parameter t. Special HOMFLY are known to depend on representation R in especially simple way: as | R|-th power of the fundamental ones. We show that the same dependence persists for our special superpolynomials in the case of symmetric representations, at least for the 2-strand torus and figure-eight knots. For antisymmetric representations the same is true, but for t = 1 and arbitrary q. It would be interesting to find an interpolation between these two relations for arbitrary representations, but no superpolynomails are yet available in this case.

Morozov, Anton

2012-12-01

128

Can human isochrony be explained by a computational theory?  

PubMed

Previous studies on human motor control reported a phenomenon called isochrony, which is the compensatory increase of movement speed with increasing movement distance. On the other hand, in complex via-points trajectory formation, a possible computational model that can estimate via-point time has been proposed. This model is optimized on the condition that the Duration average of the Commanded Torque Change (DCTC) between each via-point is equal. In this paper, we consider the possibility that human isochrony can be explained by the computational theory and investigate the human drawing movement of a set of figure eight and double elliptical patterns. Results show that isochrony was observed in both duration and DCTC and that relative variance with an increasing movement perimeter ratio of DCTC was significantly less than duration. The possibility is suggested that human isochrony is a phenomenon observed as a result of movement time planning to equalize DCTC. PMID:17946633

Saito, Hisashi; Tsubone, Tadashi; Wada, Yasuhiro

2006-01-01

129

Gyration radius of a circular polymer under a topological constraint with excluded volume.  

PubMed

It is nontrivial whether the average size of a ring polymer should become smaller or larger under a topological constraint. Making use of some knot invariants, we numerically evaluate the mean-square radius of gyration for ring polymers having a fixed knot type, where the ring polymers are given by self-avoiding polygons consisting of freely jointed hard cylinders. We obtain plots of the gyration radius versus the number of polygonal nodes for the trivial, trefoil, and figure-eight knots. We discuss possible asymptotic behaviors of the gyration radius under the topological constraint. In the asymptotic limit, the size of a ring polymer with a given knot is larger than that of no topological constraint when the polymer is thin, and the effective expansion becomes weak when the polymer is thick enough. PMID:11497553

Shimamura, M K; Deguchi, T

2001-07-11

130

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

131

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

132

A Silicon Micromachined - Microlens Scanner Array by Double-Deck Device Design Technique  

Microsoft Academic Search

In this paper, we report an array of f- thetas microlens optical scanners developed for 3-D optical cross connect (OXC) system using the bulk-silicon micromachining technique. An electrostatic XY-stage mechanism for the 2-D lens scanner was designed to have a small footprint (2 mmtimes2 mm), compared with an integrated silicon lens (diameter 1 mm) due to the newly developed double-deck

Kazuhiro Takahashi; Ho Nam Kwon; Makoto Mita; Kunihiko Saruta; Jong-Hyun Lee; Hiroyuki Fujita; Hiroshi Toshiyoshi

2007-01-01

133

Delay analysis of all-optical packet-switching ring and bus communications networks  

Microsoft Academic Search

We study the delay performance of all-optical packet communication networks configured as ring and bus topologies employing crossconnect switches (or wavelength routers). Under a cross-connect network implementation, a packet experiences no (or minimal) internal queueing delays. Thus, the network can be implemented by high speed all-optical components. We further assume a packet-switched network operation, such as that using a slotted

Izhak Rubin; Jing Ling

2001-01-01

134

Wavelength add-drop node using silica waveguide integration  

Microsoft Academic Search

We integrated a wavelength-selective cross-connect, de-interleaver, interleaver, power combiner, and variable attenuators on one silica waveguide chip and a band demultiplexer, band multiplexer, and optical monitor on another. These two chips are used to create an eight-channel add-drop node that is expandable up to 80 channels with minimal traffic interruption by adding more of these chips.

C. R. Doerr; L. W. Stulz; D. S. Levy; R. Pafchek; M. Cappuzzo; L. Gomez; A. Wong-Foy; E. Chen; E. Laskowski; G. Bogert; G. Richards

2004-01-01

135

Large N x N waveguide grating routers  

Microsoft Academic Search

We show how the grating diffraction properties of a N×N waveguide grating router (WGR) can limit the size of N when the device operates with a unique set of N wavelengths as a strict-sense nonblocking N×N cross connect. We motivate why for large N, the N optical channels should be chosen equally spaced in wavelength and not in frequency. Two

P. Bernasconi; C. Doerr; C. Dragone; M. Cappuzzo; E. Laskowski; A. Paunescu

2000-01-01

136

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

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

Cheetah Virtual Label Switch Router Design and Deployment in GMPLS Optical Networks  

Microsoft Academic Search

In this paper, we describe the design and implementation of a GMPLS software engine that is used to enable non-GMPLS switches (e.g., Ethernet switches, routers and other cross-connects) to participate in the dynamic setup and release of end-to-end bandwidth guaranteed connections. We have deployed this engine in the experimental Cheetah optical network, and hence we call it the Cheetah Virtual

Qiang Song; Zhaoming Li; Ibrahim W. Habib

2006-01-01

139

Experimental analysis of SOA-based 2R and 3R optical regeneration for future WDM networks  

Microsoft Academic Search

The large scale deployment of all-optical wavelength-division multiplexing (WDM) networks will require signal regeneration due to signal impairments occurring in transmission spans and optical switching nodes\\/cross-connects. A 2R regenerative interface for non-return to zero (NRZ) signals based on semiconductor optical amplifiers (SOAs) has been proposed by Chiaroni et al. (1997), with clear demonstration of regenerative properties in the amplitude domain.

B. Lavigne; D. Chiaroni; L. Hamon; C. Janz; A. Jourdan

1998-01-01

140

8×8 optical switch matrix using generalized Mach-Zehnder interferometers  

Microsoft Academic Search

We report an 8×8 strictly nonblocking optical cross connect (OXC) using multimode imaging (MMI)-based generalized Mach-Zehnder (MZ) interferometers realized in the silica-on-silicon planar waveguide system. Employing a router-selector architecture, this MMI-MZ OXC design results in a significantly smaller device than conventional directional-coupler based implementations. An average insertion loss of 6 dB and crosstalk of -34 dB, is demonstrated for the

M. P. Earnshaw; J. B. D. Soole; M. Cappuzzo; L. Gomez; E. Laskowski; A. Paunescu

2003-01-01

141

Roadmap to broadband ISDN  

Microsoft Academic Search

The two major emerging forms of ISDN (integrated services digital network), namely, narrowband and broadband (or B-ISDN), are contrasted. The authors note that although narrowband ISDN uses the technology of twisted pair loops, 64-Kb\\/s PCM (pulse-code modulation) circuit switches, and packet switches, B-ISDN will require fibre-optic links, digital cross connects, and optical switches; the probable network architecture of B-ISDN is

J. Ramasastry; K. S. Kim

1988-01-01

142

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); Turner, Gary W. (Clinton, TN)

2009-09-08

143

A multichip module solution for high performance ATM switching  

Microsoft Academic Search

the high industrial importance that ATM (asynchronous transfer mode) is assuming in the telecommunication environment strongly drives technology improvements. A MCM-C 16×16 Switching Element (MCM-BASE16) for the industrial ATM cross connect UTXC is presented; implementation details are described regarding both the substate characteristics and the new IBM CCGA (ceramic column grid array) packaging technique. Electrical and thermal analysis results are

L. Licciardi; M. Peretti; L. Pilati; J. J. Ichai; F. Martin; Y. Urena

1996-01-01

144

DPAS network control system, a real-time distributed self-healing network capability  

Microsoft Academic Search

The Digital Patch and Access System (DPAS), a digital cross-connect transmission system which is being deployed in the Defense Communications System, is discussed. Particular attention is given to the DPAS network control system (DNCS), a fully distributed network management system for the DPAS network. It is primarily designed to restore service to NxDS0 bandwidth circuits in order of restoration priority

J. D. Bobeck; S. P. Lee

1991-01-01

145

Scheduling switching element (SE) disjoint connections in stage-controlled photonic banyans  

Microsoft Academic Search

We study the problem of scheduling switching element (SE)-disjoint connections in banyans and dilated banyans under stage control and show how it applies to photonic cross-connect (or switch) technology. For a given set of connections (or packets), it is desirable to establish them in as few rounds as possible where the number of rounds (i.e., schedule length) corresponds to the

Chunming Qiao; Luying Zhou

1999-01-01

146

A Novel Elementary Single Electron Transistor Negative Differential Resistance Device  

NASA Astrophysics Data System (ADS)

A novel elementary single electron transistor (SET) device architecture providing negative differential resistance (NDR) is proposed and verified with SET analytical models. The proposed architecture consists of two cross-connected SETs, biased with constant current source, and it exhibits negative differential resistance for a significant range of input voltage. The effects of bias current and SET asymmetry on the circuit characteristics are shown from a design perspective. Comparison of the proposed architecture with other NDR devices is also presented.

Mahapatra, Santanu; Ionescu, Adrian Mihai

2004-02-01

147

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

148

Micromirrors: overview and application roadmap  

NASA Astrophysics Data System (ADS)

The Telecom sector has driven until 2000 the development of micro-mirrors with subsystems like optical cross-connects and add/drop multiplexers for all-optical networks. Following the collapse of the telecom equipment market, much attention has been given to emerging applications in consumer electronics, IT, industry, and biomedical. WTC will give an overview on existing and emerging markets of micro-mirrors outside telecom. The various micro-mirror techniques and their respective applications from high value niches to mass markets will be presented. The supply chain will be analysed and a roadmap of implementation of micro-mirrors will be proposed.

Bouchaud, Jeremie; Bahle, Carsten; Wicht, Henning

2005-01-01

149

Development of a detailed core flow analysis code for prismatic fuel reactors  

SciTech Connect

The development of a computer code for the analysis of the detailed flow of helium in prismatic fuel reactors is reported. The code, called BYPASS, solves, a finite difference control volume formulation of the compressible, steady state fluid flow in highly cross-connected flow paths typical of the Modular High-Temperature Gas Cooled Reactor (MHTGR). The discretization of the flow in a core region typically considers the main coolant flow paths, the bypass gap flow paths, and the crossflow connections between them. 16 refs., 5 figs.

Bennett, R.G.

1990-01-01

150

Lamar repowering project's creative modeling of old and new wins Marmaduke award  

SciTech Connect

Lamar Light and Power is a municipal utility that has been generating the south eastern Colorado city's electricity since 1920. Rising natural gas and oil costs pushed LL & P to retire its steam plant five years ago and begin hunting for more economic power sources. The answer: repower the existing plant with a state-of-the-art coal-fired circulating fluidized-bed combustor and cross-connect old and new steam turbines. The 120 million dollar project will stabilize the region's electricity rates for many years to come. 10 figs. 1 tab.

Peltier, R.

2008-08-15

151

Microwave photonic filters using low-cost sources featuring tunability, reconfigurability and negative coefficients.  

PubMed

We propose and experimentally demonstrate two configurations of photonic filters for the processing of microwave signals featuring tunability, reconfigurability and negative coefficients based on the use of low cost optical sources. The first option is a low power configuration based on spectral slicing of a broadband source. The second is a high power configuration based on fixed lasers. Tunability, reconfigurability and negative coefficients are achieved by means of a MEMS cross-connect, a variable optical attenuator array and simple 2x2 switches respectively. PMID:19495017

Capmany, José; Mora, José; Ortega, Beatriz; Pastor, Daniel

2005-03-01

152

Repetitive magnetic stimulation of cortical motor areas in Parkinson's disease: implications for the pathophysiology of cortical function.  

PubMed

We investigated the neurophysiological and clinical effects of repetitive magnetic stimulation (rTMS) delivered to the cortical motor areas in healthy subjects and patients with Parkinson's disease. rTMS was delivered with a high speed magnetic stimulator (Cadwell, Kennewick, WA) through a figure-eight coil centred on the primary motor area at a stimulus intensity of 120% motor threshold. Trains of 10 stimuli were delivered at frequencies of 5 Hz while subjects were at rest and during a voluntary contraction of the contralateral first dorsal interosseous muscle. In normal subjects at rest, the muscle evoked responses (MEPs) to each stimulus in a train of magnetic stimuli progressively increased in size during the train. rTMS left the MEPs unchanged in patients off therapy and had a small facilitatory effect in those on therapy. In normal subjects and patients, 5-Hz rTMS trains delivered during a voluntary contraction of the target muscle left the MEP unchanged in size. MEPs were followed by a silent period that increased in duration during the course of the train. The silent period duration increased to a similar extent in patients and controls. The reduced rTMS-induced facilitation of MEPs in patients with Parkinson's disease reflects a decreased facilitation of the excitatory cells in the cortical motor areas. PMID:12112192

Gilio, F; Currà, A; Inghilleri, M; Lorenzano, C; Manfredi, M; Berardelli, Alfredo

2002-05-01

153

Conformations of some lower-size large-ring cyclodextrins derived from conformational search with molecular dynamics and principal component analysis  

NASA Astrophysics Data System (ADS)

Computational studies were conducted on the conformations of some lower-size large-ring cyclodextrins, CDn (n = 11, 12, 13, 15, 16, 17). Principal component analysis (PCA) was applied for post-processing of trajectories from conformational search based on 100.0 ns molecular dynamics (MD) simulations. The dominant PCA modes for concerted motions of the macroring atoms were monitored in a lower-dimensions subspace. The first six lowest indexed principal components contribute more than 90% of the total atomic motions in all cases, with about 70% (CD12) to 90% (CD17) contribution coming from the three highest-eigenvalue principal components. Representative average geometries of the cyclodextrin macrorings were also obtained for the whole simulation and for the ten 10.0 ns time intervals of the simulation. We concluded that the whole set of structures could be sorted into two clearly distinguished groups, separated by the figure-eight conformation of CD14: (i) open bent boat-like macrorings (CD11 to CD13), and (ii) two winded single helical strands (an anti-parallel double helix with foldbacks at each end), CD15 to CD17, shaped as number eight for the odd-number-residues cases, CD15 and CD17. CD13 and CD14 mark the borderline between lower and higher flexibilities of the lower-size LR-CDs macrorings.

Ivanov, Petko

2012-02-01

154

Functional outcomes of conservatively treated clavicle fractures  

PubMed Central

OBJECTIVE: The main aim of the study was to analyze the outcomes of clavicle fractures in adults treated non-surgically and to evaluate the clinical effects of displacement, fracture patterns, fracture location, fracture comminution, shortening and fracture union on shoulder function. METHODS: Seventy clavicle fractures were non-surgically treated in the Orthopedics Department at the Tuanku Ja'afar General Hospital, a tertiary care hospital in Seremban, Malaysia, an average of six months after injury. The clavicle fractures were treated conservatively with an arm sling and a figure-eight splint for three weeks. No attempt was made to reduce displaced fractures, and the patients were allowed immediate free-shoulder mobilization, as tolerated. They were prospectively evaluated clinically and radiographically. Shoulder function was evaluated using the Constant scoring technique. RESULTS: There were statistically significant functional outcome impairments in non-surgically treated clavicle fractures that correlated with the fracture type (comminution), the fracture displacement (21 mm or more), shortening (15 mm or more) and the fracture union (malunion). CONCLUSION: This article reveals the need for surgical intervention to treat clavicle fractures and improve shoulder functional outcomes.

Bajuri, Mohd Yazid; Maidin, S; Rauf, A; Baharuddin, M; Harjeet, S

2011-01-01

155

Compensation techniques in accelerator physics  

NASA Astrophysics Data System (ADS)

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.

Sayed, Hisham Kamal

156

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

157

How Do Honeybees Attract Nestmates Using Waggle Dances in Dark and Noisy Hives?  

PubMed Central

It is well known that honeybees share information related to food sources with nestmates using a dance language that is representative of symbolic communication among non-primates. Some honeybee species engage in visually apparent behavior, walking in a figure-eight pattern inside their dark hives. It has been suggested that sounds play an important role in this dance language, even though a variety of wing vibration sounds are produced by honeybee behaviors in hives. It has been shown that dances emit sounds primarily at about 250–300 Hz, which is in the same frequency range as honeybees' flight sounds. Thus the exact mechanism whereby honeybees attract nestmates using waggle dances in such a dark and noisy hive is as yet unclear. In this study, we used a flight simulator in which honeybees were attached to a torque meter in order to analyze the component of bees' orienting response caused only by sounds, and not by odor or by vibrations sensed by their legs. We showed using single sound localization that honeybees preferred sounds around 265 Hz. Furthermore, according to sound discrimination tests using sounds of the same frequency, honeybees preferred rhythmic sounds. Our results demonstrate that frequency and rhythmic components play a complementary role in localizing dance sounds. Dance sounds were presumably developed to share information in a dark and noisy environment.

Hasegawa, Yuji; Ikeno, Hidetoshi

2011-01-01

158

Tendon suspension sling arthroplasty for thumb trapeziometacarpal arthritis.  

PubMed

Forty consecutive tendon suspension sling arthroplasties for relief of pantrapezial osteoarthritis in 38 patients were reviewed. The procedure consists of excision of the trapezium and reconstitution of the tethering action of the first intermetacarpal and the palmar oblique carpometacarpal ligaments; 50% of the distally based flexor carpi radialis tendon is used. A double figure-eight sling suspends the first metacarpal securely, followed by distal advancement of the abductor pollicis longus to tighten the sling and palmarly abduct the thumb ray. The technique resulted in relief of pain, preservation of strength, maintenance of a normally contoured first web space, and functional carpometacarpal range of motion. Procedures were performed over a 4-year period (1986 to 1990), with an average follow-up of 21 months. At final follow-up, 85% of the patients had minimal symptoms; key pinch and grip strengths measured 76% and 81% of the contralateral uninvolved side, respectively. The logic of the mechanical design of the procedure and encouraging subjective and objective follow-up at 4 years make the technique of tendon suspension sling arthroplasty an attractive alternative to existing procedures for the surgical management of recalcitrant and disabling osteoarthritis of the basilar thumb joint. PMID:1748769

Kleinman, W B; Eckenrode, J F

1991-11-01

159

Super-A-polynomial for knots and BPS states  

NASA Astrophysics Data System (ADS)

We introduce and compute a 2-parameter family deformation of the A-polynomial that encodes the color dependence of the superpolynomial and that, in suitable limits, reduces to various deformations of the A-polynomial studied in the literature. These special limits include the t-deformation which leads to the "refined A-polynomial" introduced in the previous work of the authors and the Q-deformation which leads, by the conjecture of Aganagic and Vafa, to the augmentation polynomial of knot contact homology. We also introduce and compute the quantum version of the super-A-polynomial, an operator that encodes recursion relations for Sr-colored HOMFLY homology. Much like its predecessor, the super-A-polynomial admits a simple physical interpretation as the defining equation for the space of SUSY vacua (= critical points of the twisted superpotential) in a circle compactification of the effective 3d N=2 theory associated to a knot or, more generally, to a 3-manifold M. Equivalently, the algebraic curve defined by the zero locus of the super-A-polynomial can be thought of as the space of open string moduli in a brane system associated with M. As an inherent outcome of this work, we provide new interesting formulas for colored superpolynomials for the trefoil and the figure-eight knot.

Fuji, Hiroyuki; Gukov, Sergei; Su?kowski, Piotr

2013-02-01

160

General atomic response to resonant, phase-fluctuating fields in the adiabatic limit  

NASA Astrophysics Data System (ADS)

Though the interaction of a two-level atom with a field undergoing some arbitrary pattern of phase variation may be obtained by a numerical solution of the density-matrix equations, theory has proven to be problematic in providing a general, intuitive picture of the atom's response to a phase-varying field. The convolution picture of the fluctuating field-atom interaction, known to spectroscopists for decades, is only valid in the regime of weak fields. Here we discuss a complementary intuitive view that is valid in the regime of strong, resonant fields. Specifically, when an atom's response to a phase-varying field is considered in the instantaneous frame, the Bloch-vector trajectory always traces out a ``figure-eight''-type pattern, reminiscent of a Lissajous figure. This observation is demonstrated for a number of fields whose phase-varying patterns span a broad range (i.e., sinusoidal, two-frequency quasiperiodic, chaotic, stochastic), and analysis of the Bloch-vector equations then reveals the complete generality of this response. The analysis also reveals that the temporal variation of the atomic population to phase fluctuations in the strong, resonant field regime is nearly proportional to a simple product of the field's phase and its first derivative.

Frueholz, R. P.; Camparo, J. C.

1995-07-01

161

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

162

Occlusion of large atrial septal defects with a centering buttoned device: early clinical experience.  

PubMed

A feasibility clinical study was conducted for the transcatheter occlusion of large ostium secundum atrial septal defects with the centering buttoned device. The centering buttoned device is a modification of the regular buttoned device in which a centering counter-occluder is sutured at the central 40% portion of the occluder. During centering it is stretched, forming a parachute-shaped structure and pulling the occluder over the center of the defect. During buttoning, the counter-occluder forms a double figure eight, opposing the right atrial side of the atrial septum. Occlusion was performed in 12 patients aged 6 to 56 years. All had been rejected for transcatheter occlusion by the regular buttoned device, because of either their defect size or the lack of adequate septal rim. The defect size varied between 23 and 31 mm, and the device size varied between 45 and 60 mm. Nine had immediate effective occlusions of their defects and three residual shunts. One patient with unbuttoning had hemolysis at 2 weeks and underwent surgery. Early results of the transcatheter occlusion of large atrial septal defects are promising, and larger clinical trials are justified. PMID:8579033

Sideris, E B; Leung, M; Yoon, J H; Chen, C R; Lochan, R; Worms, A M; Rey, C; Meier, B

1996-02-01

163

Trajectories of Listeria-type motility in two dimensions  

NASA Astrophysics Data System (ADS)

Force generated by actin polymerization is essential in cell motility and the locomotion of organelles or bacteria such as Listeria monocytogenes. Both in vivo and in vitro experiments on actin-based motility have observed geometrical trajectories including straight lines, circles, S-shaped curves, and translating figure eights. This paper reports a phenomenological model of an actin-propelled disk in two dimensions that generates geometrical trajectories. Our model shows that when the evolutions of actin density and force per filament on the disk are strongly coupled to the disk self-rotation, it is possible for a straight trajectory to lose its stability. When the instability is due to a pitchfork bifurcation, the resulting trajectory is a circle; a straight trajectory can also lose stability through a Hopf bifurcation, and the resulting trajectory is an S-shaped curve. We also show that a half-coated disk, which mimics the distribution of functionalized proteins in Listeria, also undergoes similar symmetry-breaking bifurcations when the straight trajectory loses stability. For both a fully coated disk and a half-coated disk, when the trajectory is an S-shaped curve, the angular frequency of the disk self-rotation is different from that of the disk trajectory. However, for circular trajectories, these angular frequencies are different for a fully coated disk but the same for a half-coated disk.

Wen, Fu-Lai; Leung, Kwan-tai; Chen, Hsuan-Yi

2012-12-01

164

[Electrovectorcardiographic manifestations of supraventricular ectopic rhythms (an interpretive hypothesis)].  

PubMed

When a low right atrial rhythm is present, P waves are negative in the low leads, they are variable in a VR and positive in a VL and LI. The figure eighth PF loop is located in the first quadrant, the PH loop has a counterclockwise rotation, and the PS can rotate in either direction. In the presence of upper left atrial rhythms, P waves are positive in the low leads and negative in a VL and a VR. The PF and PH loops can be found in the third quadrant of both planes with a clockwise rotation. If the rhythm originates in low left atrial regions, negative P waves are recorded in left precordial leads and positive ones in a VR and a VL. The PF loop has counterclockwise rotation or its branches superimposed and is situated in the second quadrant; PH with clockwise rotation is registered in the third quadrant; PS with either counterclockwise or clockwise rotation develops above and slightly ahead of the E point. When a nodal rhythm exists, P waves are negative in the low leads. The P loops show a counterclockwise rotation or a figure eight morphology. In the absence of atrial enlargements, the PF loop can be recorded in the first quadrant and the PH in the first or the fourth quadrant. PMID:2696444

de Micheli, A; Medrano, G A

165

How do honeybees attract nestmates using waggle dances in dark and noisy hives?  

PubMed

It is well known that honeybees share information related to food sources with nestmates using a dance language that is representative of symbolic communication among non-primates. Some honeybee species engage in visually apparent behavior, walking in a figure-eight pattern inside their dark hives. It has been suggested that sounds play an important role in this dance language, even though a variety of wing vibration sounds are produced by honeybee behaviors in hives. It has been shown that dances emit sounds primarily at about 250-300 Hz, which is in the same frequency range as honeybees' flight sounds. Thus the exact mechanism whereby honeybees attract nestmates using waggle dances in such a dark and noisy hive is as yet unclear. In this study, we used a flight simulator in which honeybees were attached to a torque meter in order to analyze the component of bees' orienting response caused only by sounds, and not by odor or by vibrations sensed by their legs. We showed using single sound localization that honeybees preferred sounds around 265 Hz. Furthermore, according to sound discrimination tests using sounds of the same frequency, honeybees preferred rhythmic sounds. Our results demonstrate that frequency and rhythmic components play a complementary role in localizing dance sounds. Dance sounds were presumably developed to share information in a dark and noisy environment. PMID:21603608

Hasegawa, Yuji; Ikeno, Hidetoshi

2011-05-16

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

Respiratory pattern in midline-lesioned brainstems and hemibrainstems from adult turtles  

PubMed Central

Discrete midline lesions uncouple left and right respiratory motor output in mammals, but not in frogs and lampreys. To address this question in reptiles, isolated adult turtle brainstems were cut along the midline while recording respiratory motor output (bursts of action potentials) on left and right hypoglossal (XII) nerves. XII motor bursts were synchronized as long as a small portion of the midline was still intact. When turtle brainstems were completely cut along the midline and separated into hemibrainstems, XII motor bursts were produced that could be abolished by mu-opioid receptor (MOR) activation or exposure to high pH (7.80) solution. Also, 13/57 hemibrainstems expressed episodic discharge (>1.75 bursts/episode). To test whether crossed connections were necessary to express a long-lasting increase in burst frequency (i.e., frequency plasticity), phenylbiguanide (PBG, 5-HT3 receptor agonist, 20 ?M) was bath-applied to hemibrainstems. Although PBG significantly increased burst frequency by 0.43 ± 0.10 bursts/min after 60 min, no frequency plasticity was observed because burst frequency returned to near baseline levels after a 2-h washout. Thus, crossed connections in turtle brainstems synchronize respiratory motor output and are not required for normal respiratory pattern formation, but are required for PBG-dependent frequency plasticity.

Majewski, David J.; Wiegel, Liana M.; Johnson, Stephen M.

2010-01-01

168

MOEMS for optical communication: status of the European industrial activities and technical and economical trends for the next three years  

NASA Astrophysics Data System (ADS)

The fiber-optic telecommunication market has dramatically evolved. Over the 1999-2000 period, almost $110 billion have been exchanged for companies and new technology acquisitions by large groups. This market continues to stimulate the creation of new start-ups. 2 to 5 companies are created every month in Europe in this field and the same in the USA and numerous other ones are in launching phase. Moreover, there are still high investment efforts form Venture Capitalists in this field. Today, it is obvious that fiber-optics telecom is the new Killer Applications that microsystems technology was looking for. As the objective is to have all-optical routing systems, the routing function could be achieved using MEMS components, which is the only technology which could cope with the realization of large matrix size cross-connects. Moreover, as demand is not uniform in the network, there is also a growing need for reconfiguration of parts of the network (to create regions of higher capacity for example). MEMS are suitable components for reconfiguration: WDM add/drop, optical cross-connect or optical switches. The presentation will make the up-to-date analysis on who is doing what in this field in Europe and what are the products for which applications on MEMS for optical telecom.

Mounier, Eric; Eloy, Jean-Christophe

2001-10-01

169

Character Expansion for Homfly Polynomials Iii: all 3-STRAND Braids in the First Symmetric Representation  

NASA Astrophysics Data System (ADS)

We continue the program of systematic study of extended HOMFLY polynomials, suggested in [A. Mironov, A. Morozov and And. Morozov, arXiv:1112.5754] and [A. Mironov, A. Morozov and And. Morozov, J. High Energy Phys. 03, 034 (2012), arXiv:1112.2654]. Extended polynomials depend on infinitely many time-variables, are close relatives of integrable ?-functions, and depend on the choice of the braid representation of the knot. They possess natural character decompositions, with coefficients which can be defined by exhaustively general formula for any particular number m of strands in the braid and any particular representation R of the Lie algebra GL(?). Being restricted to "the topological locus" in the space of time-variables, the extended HOMFLY polynomials reproduce the ordinary knot invariants. We derive such a general formula, for m = 3, when the braid is parametrized by a sequence of integers (a1, b1, a2, b2, …) and for the first nonfundamental representation R = [2]. Instead of calculating the mixing matrices directly, as suggested [A. Mironov, A. Morozov and And. Morozov, J. High Energy Phys. 03, 034 (2012), arXiv:1112.2654], we deduce them from comparison with the known answers for torus and composite knots. A simple reflection symmetry converts the answer for the symmetric representation [2] into that for the antisymmetric one [1, 1]. The result applies, in particular, to the figure eight knot 41, and was further extended to superpolynomials in arbitrary symmetric and antisymmetric representations in H. Itoyama, A. Mironov, A. Morozov and And. Morozov, arXiv:1203.5978.

Itoyama, H.; Mironov, A.; Morozov, A.; Morozov, And.

2012-07-01

170

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

171

Extremely low-frequency response (below 30 Hz) of UXO-like objects  

NASA Astrophysics Data System (ADS)

Extremely low frequency measurements, below 30 Hz, of solid, thin-, and, thick-walled steel (permeable) cylinders with length-to-diameter ratios of approximately 4 are described and compared with the predicted response computed using a frequency domain finite element method (FDFEM). Measurements were made using a conventional EMI test setup consisting of a Hewlett Packard 89410 vector signal analyzer, rectangular transmitting and a figure-eight (bucked) receiving coil, along with appropriate transmitter and receiver coil amplifiers. All cylinders were measured with the predominant component of the excitatory magnetic field both aligned with and orthogonal to (two distinct measurements) the cylinder's axis. Measurements were made with and without a centered copper ring on the cylinders. The ring simulates the so-called rotating bands on actual UXO. Not surprisingly, we observed that the quadrature peak of the response shifts down in frequency much more when the axis of the ringed cylinder is aligned with the excitatory magnetic field than when perpendicular to it. Our measurements indicated that the real part of the response of the smallest cylinders measured asymptotically approaches its DC value around 1 Hz while the largest of the cylinders measured does not asymptote until well below 1 Hz. It appears that target information that may be crucial for discrimination purposes, especially for larger targets, exists at frequencies well below 30 Hz. Extremely low frequency measurements, especially with data averaging (stacking), can be a rather time consuming process, and therefore it is not likely that such measurements can be made from a moving platform. However, once an object of interest has been detected, the target can be reacquired and the measurement taken with the sensor stationary with respect to the target (sometimes referred to as a qued approach). As our measurements and simulations indicate, the qued method may be necessary if large solid UXO are to be distinguished from large thin-walled clutter objects.

Chilaka, Sailaja V.; Riggs, Lloyd S.; Nelson, Herbert H.; Bell, Thomas H.

2004-09-01

172

Skeletal muscle powered pumps can work under low preload. Design considerations.  

PubMed

Characteristics of a dual chambered, single layered skeletal muscle powered pump (DCSLP) and a single chamber, multilayered pump (SCMLP) made from similar masses of untrained latissimus dorsi muscle (LD) were compared. For the DCSLP, 16 canine LDs (51.5 +/- 1.6 g) were wrapped in a "figure eight" around two parallel mandrels, whereas for the SCMLP, LDs were made in 10 by wrapping the LD (54 +/- 8.5 g) twice around one mandrel. Chamber compliance and pump isovolumic peak developed pressure (PDP), stroke volume (SV), stroke work (SW), and ejection fraction (EF) of single contractions were measured. In six of the DCSLP dogs (LV), heart left ventricular stroke volume (LVSV) and left ventricular stroke work (LVSW) were determined. Stimulation parameters were the same for all. Student's t-test (* = p < 0.05) was used for statistical analysis. Dual chambered, single layered skeletal muscle powered pumps with a diastolic volume/mass ratio of 0.63 were more compliant than SCMLPs with a ratio of 0.37. Single chamber, multilayered pumps generated slightly higher PDP, but this was significant only at 60 mmHg preload. At a preload of 15 and an afterload of 120 mmHg, DCSLPs had higher SV (10.7 +/- 1.1 ml) and SW (0.98 +/- 0.14 x 10(6) ergs) than SCMLPs (6.8 +/- 0.7 ml* and 0.58 +/- 0.08 x 10(6) ergs*), or their LV counterparts (5.3 +/- 0.9 ml and 0.84 +/- 0.22 x 10(6) ergs).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1457878

Oda, T; Miyamoto, A T; Okamoto, Y; Ban, T

173

The Ecogeomorphology of Salt Pools of the Webhannet Estuary, Wells, Maine, USA  

NASA Astrophysics Data System (ADS)

Salt pools are shallow, muddy depressions in salt marshes that remain flooded throughout the entire tidal cycle. They are common landforms of this ecosystem, but little is known for certain about their formation and persistence through time. Understanding the ontogeny of salt pools is critical, as it has been suggested that they may serve as important habitat for some birds and fish, and as indicators of ultimate marsh break-up and wetland loss. Hypotheses regarding pool initiation have suggested that pools are primary features of marshes, while others have suggested that pools form through secondary mechanisms such as isolated vegetative die-off or ice-plucking. Still others have suggested that pools may be associated with tidal creek abandonment. This study combines field observations, geologic coring, and analyses of a time-series of aerial photographs through geographic information systems (GIS), to quantify the recent history of pools of the Webhannet Estuary, Wells, ME, USA. Six transects sampled 119 pools during Summers 2004/2005. Adjacent percent vegetative cover (3, 1m2 plots/pool), bank classification (graded, mostly graded, mostly steep, steep), pool shape (circular, figure eight, irregular, sinuous) and a handheld GPS point were recorded. GPS data points were imported into a GIS platform to determine spatial trends. Examination of the spatial distribution suggests that pools are not randomly distributed across the marsh surface, but rather exhibit strong spatial patterns based on the pool characteristics described. Preliminary analyses of aerial photographs comparing the marsh surface in 1953 to 2003, suggest pools exhibit different developmental sequences over time (some grow, some shrink, some remain the same in area and shape). Dutch cores taken during Summer 2005 reveal a distinct pool signature and suggest that some pools may be of a more ephemeral nature than previously described and support the hypothesis that pools form through secondary mechanisms. New understanding of the development of salt pools may have practical management implications.

Wilson, K. R.; Kelley, J. T.

2005-12-01

174

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

175

[Vectorcardiographic manifestations of atrial enlargements].  

PubMed

Rational interpretation of changes of the P loop due to atrial enlargements must to rely on the magnitude and spatial orientation of main resultant vectors of the activation sequence of the atria. Under normal conditions, these vectors give rise to a mean vector oriented to the left downward and discretely forward with respect to their point of origin. In the presence of right atrial enlargement, the manifestation of the first vector of atrial depolarization, oriented downward and forward, is increased. This one moves in the same direction as the mean vector of atrial depolarization, originating an elongated P loop of more than 100 mcv in the three planes. Nevertheless, in the horizontal plane, increase of the P loop voltage predominates when hypertrophy exists, while augmentation of its area predominates when dilatation exists. In left atrial enlargement, the manifestation of the second vector of atrial depolarization, oriented to the left and backward, is augmented, and it moves in the same direction as the mean vector of atrial depolarization. For this, the PF loop acquires a characteristic aspect of a boxing glove, an the PH loop becomes diphasic, with its posterior area more or less prominent, or with a typical figure-eight conformation. If a biatrial enlargement is present, the manifestation of both the main resultant vectors of atrial depolarization is accentuated. Therefore the voltage of the diphasic P loop increases. Moreover the Ps loop has a triangular configuration, with its base of 30 msc or more, located below its point of origin. Generally disturbances of interatrial and intraatrial conduction coexist owing to myocardial damage. PMID:2146934

de Micheli, A; Medrano, G A

176

Modeling of mode-locked fiber lasers  

NASA Astrophysics Data System (ADS)

This thesis presents the results of analytical and numerical simulations of mode-locked fiber lasers and their components: multiple quantum well saturable absorbers and nonlinear optical loop mirrors. Due to the growing interest in fiber lasers as a compact source of ultrashort pulses there is a need to develop a full understanding of the advantages and limitations of the different mode-locked techniques. The mode-locked fiber laser study performed in this thesis can be used to optimize the design and performance of mode-locked fiber laser systems. A group at Air Force Research Laboratory reported a fiber laser mode-locked by multiple quantum well (MQW) saturable absorber with stable pulses generated as short as 2 ps [21]. The laser cavity incorporates a chirped fiber Bragg grating as a dispersion element; our analysis showed that the laser operates in the soliton regime. Soliton perturbation theory was applied and conditions for stable pulse operation were investigated. Properties of MQW saturable absorbers and their effect on cavity dynamics were studied and the cases of fast and slow saturable absorbers were considered. Analytical and numerical results are in a good agreement with experimental data. In the case of the laser cavity with a regular fiber Bragg grating, the properties of MQW saturable absorbers dominate the cavity dynamics. It was shown that despite the lack of a soliton shaping mechanism, there is a regime in parameter space where stable or quasi-stable solitary waves solutions can exist. Further a novel technique of fiber laser mode-locking by nonlinear polarization rotation was proposed. Polarization rotation of vector solitons was simulated in a birefringent nonlinear optical loop mirror (NOLM) and the switching characteristics of this device was studied. It was shown that saturable absorber-like action of NOLM allows mode-locked operation of the two fiber laser designs. Laser cavity designs were proposed: figure-eight-type and sigma-type cavity.

Shaulov, Gary

177

Prefrontal cortex and hippocampus subserve different components of working memory in rats  

PubMed Central

Both the medial prefrontal cortex (mPFC) and hippocampus are implicated in working memory tasks in rodents. Specifically, it has been hypothesized that the mPFC is primarily engaged in the temporary storage and processing of information lasting from a subsecond to several seconds, while the hippocampal function becomes more critical as the working memory demand extends into longer temporal scales. Although these structures may be engaged in a temporally separable manner, the extent of their contributions in the “informational content” of working memory remains unclear. To investigate this issue, the mPFC and dorsal hippocampus (dHPC) were temporarily inactivated via targeted infusions of the GABAA receptor agonist muscimol in rats prior to their performance on a delayed alternation task (DAT), employing an automated figure-eight maze that required the animals to make alternating arm choice responses after 3-, 30-, and 60-sec delays for water reward. We report that inactivation of either the mPFC or dHPC significantly reduced DAT at all delay intervals tested. However, there were key qualitative differences in the behavioral effects. Specifically, mPFC inactivation selectively impaired working memory (i.e., arm choice accuracy) without altering reference memory (i.e., the maze task rule) and arm choice response latencies. In contrast, dHPC inactivation increased both reference memory errors and arm choice response latencies. Moreover, dHPC, but not mPFC, inactivation increased the incidence of successive working memory errors. These results suggest that while both the mPFC and hippocampus are necessarily involved in DAT, they seem to process different informational components associated with the memory task.

Yoon, Taejib; Okada, Jeffrey; Jung, Min W.; Kim, Jeansok J.

2008-01-01

178

DNA-bridging by a palindromic alpha-helix.  

PubMed Central

The nucleosomal DNA repeat of 240 base pairs in the chromatin structure of sea urchin sperm is exceptionally long and is accompanied by the presence of a histone H1 molecule larger than is usual in most species of chromatin. I propose how these two features are correlated and how they fit into the solenoidal model for the 300-A-diameter fiber of chromatin. Comparison of the sequence of spermatogenous H1 with other H1 sequences reveals an insert of 55 amino acid residues (residues 122-176). A 37-residue sequence in the insert (residues 140-176) has a palindromic character. I propose that each half of the palindromic sequence constitutes an alpha-helical DNA-binding unit and that the continuous alpha-helix made up of the two halves, by virtue of its palindromic nature, stabilizes the formation of an extra superhelical turn by the long linker DNA between two nucleosome cores. The N-terminal-C-terminal "polarity" of each alpha-helical section of half the palindromic sequence indicates how the arginine/lysine-rich DNA-binding surface of the alpha-helical section is used. The polarity of the H1 insertion sequence supports the so-called "reverse-loop" model or a "figure-eight" model for the path of the DNA within the solenoid structure; i.e., the linker DNA forms a right-handed superhelical turn toward the center of the solenoid structure. This use of a pair of a palindromically related alpha-helical sections has a similarity with the "scissors-grip" model for the interaction of the leucine-zipper proteins with DNA. Images

Suzuki, M

1992-01-01

179

The genetic landscape of a cell.  

PubMed

A genome-scale genetic interaction map was constructed by examining 5.4 million gene-gene pairs for synthetic genetic interactions, generating quantitative genetic interaction profiles for approximately 75% of all genes in the budding yeast, Saccharomyces cerevisiae. A network based on genetic interaction profiles reveals a functional map of the cell in which genes of similar biological processes cluster together in coherent subsets, and highly correlated profiles delineate specific pathways to define gene function. The global network identifies functional cross-connections between all bioprocesses, mapping a cellular wiring diagram of pleiotropy. Genetic interaction degree correlated with a number of different gene attributes, which may be informative about genetic network hubs in other organisms. We also demonstrate that extensive and unbiased mapping of the genetic landscape provides a key for interpretation of chemical-genetic interactions and drug target identification. PMID:20093466

Costanzo, Michael; Baryshnikova, Anastasia; Bellay, Jeremy; Kim, Yungil; Spear, Eric D; Sevier, Carolyn S; Ding, Huiming; Koh, Judice L Y; Toufighi, Kiana; Mostafavi, Sara; Prinz, Jeany; St Onge, Robert P; VanderSluis, Benjamin; Makhnevych, Taras; Vizeacoumar, Franco J; Alizadeh, Solmaz; Bahr, Sondra; Brost, Renee L; Chen, Yiqun; Cokol, Murat; Deshpande, Raamesh; Li, Zhijian; Lin, Zhen-Yuan; Liang, Wendy; Marback, Michaela; Paw, Jadine; San Luis, Bryan-Joseph; Shuteriqi, Ermira; Tong, Amy Hin Yan; van Dyk, Nydia; Wallace, Iain M; Whitney, Joseph A; Weirauch, Matthew T; Zhong, Guoqing; Zhu, Hongwei; Houry, Walid A; Brudno, Michael; Ragibizadeh, Sasan; Papp, Balázs; Pál, Csaba; Roth, Frederick P; Giaever, Guri; Nislow, Corey; Troyanskaya, Olga G; Bussey, Howard; Bader, Gary D; Gingras, Anne-Claude; Morris, Quaid D; Kim, Philip M; Kaiser, Chris A; Myers, Chad L; Andrews, Brenda J; Boone, Charles

2010-01-22

180

Photonic packet routing based on multiwavelength label switch using multisection fiber Bragg gratings  

NASA Astrophysics Data System (ADS)

We are developing photonic packet switching system called multi-wavelength label switching node (M(lambda) -LSN). This is a desired system to build ultra high-speed packet switching. The M(lambda) -LSN analyzes the label all- optically. The photonic packet switching can be achieved with the help of optical packet with a multi-wavelength label. Different from an optical cross-connect (OXC) in a wavelength routing network, the M(lambda) -LSN inherently has fine granularity. The M(lambda) -LSN consists of photonic forwarding (label lookup), photonic switching, electronic scheduling, and photonic buffering. We describe demonstrations in the photonic packet routing based on multi-wavelength label switch. All-optical functions, variable data rate switching, variable length packet switching, label swapping, and label merge (replacing multiple labels by a single label) are demonstrated. We describe multi-stage fiber delay line buffer architecture to compensate for gap between electronic scheduling speed and optical data rate.

Wada, Naoya; Harai, Hiroaki

2002-07-01

181

Plasma pressure generated auroral current system: A case study  

NASA Astrophysics Data System (ADS)

An anti-sunward directed azimuthal pressure gradient drives 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 cross connected in the ionosphere. Using a conjunction of FAST and Polar the intensity of the up-down sheet FAC pair was measured in the dusk sector in typical auroral conditions. The T96 field model was used to define the geometry and it predicted that field lines at the satellites were stretched to 15 RE. The steady state pressure gradient current was calculated through a surface in the magnetosphere separating the upward and downward going FAC. With the field stretching predicted by the model a typical quiet time azimuthal pressure gradient of 0.01 nPa/Re generated sufficient current to be the source of the observed auroral current loops.

Mende, S. B.; England, S. L.; Frey, H. U.

2012-03-01

182

Waveband switching in light trail optical networks with dynamic traffic [Invited  

NASA Astrophysics Data System (ADS)

Wavelength switching is used in current light-path networks to set up connections between node pairs. With the increase in the number of wavelengths per fiber, waveband switching has been proposed for decreasing the number of switching ports in optical nodes. Another concept called a 'light trail' allows the intermediate nodes along a light path to access the wavelength channel, aiming at the reduction of the total number of wavelengths. Both techniques apply traffic grooming on different levels of a WDM network. We combine and compare these two switching techniques: waveband switching light path (WBS-LP) and waveband switching light trail (WBS-LT). For both WBS-LP and WBS-LT networks, auxiliary graph models are proposed to exploit not only the wavelength resources in the fiber links but also the limited waveband port resources inside multigranular optical cross connect (MG-OXC) nodes.

Ye, Yabin; Woesner, Hagen; Chlamtac, Imrich

2006-10-01

183

Optimal design for survivable backbones with end-to-end and subpath wavebanding  

NASA Astrophysics Data System (ADS)

We deal with the optimal design of a survivable optical mesh network supporting end-to-end and subpath waveband switching (WBS) in order to compare various WBS schemes according to a given cost function. An integer linear programming formulation is proposed to minimize the global network cost, which is expressed in terms of port cost, fiber cost, and propagation delay cost. We assume a single-layer multigranularity optical cross-connect (MG-OXC) node with a variable number of incoming fibers and a fixed number of wavelengths per waveband. The results show that on our case-study networks WBS with joint end-to-end and subpath wavebanding guarantees a gain of up to 22% and 85% in port number and global network costs, respectively.

Secci, Stefano; Tornatore, Massimo; Pattavina, Achille

2007-01-01

184

MANS and ATM: evolution, interconnection, and interworking  

NASA Astrophysics Data System (ADS)

This paper, based on work within RACE project R1022 -- `Technology for ATD,' places the evolution of MANs towards ATM within the overall context of ATM introduction and evolution. Beginning with a major motivating factor, the need for LAN to LAN interconnection, a likely evolution of MANs is described, from first introduction, through interconnection via the ATM cross connect network, to the provision of connectionless data service over the ATM network. The introduction and evolution of ATM in general is then considered. This begins with a review of basic introductory approaches (substitution, island, overlay) and how they can be applied. An overview of the main customer groupings and their likely service requirements is provided as a precursor to discussing how fiber will be used in the access network for both business and residential customers. The paper concludes with an assessment of how MAN evolution towards ATM fits within the overall context of ATM introduction and the provision of broadband services.

Sara, Lini; Cuthbert, Laurie; Pitts, Jonathan

1993-10-01

185

Notch tumor suppressor function  

PubMed Central

Cancer development results from deregulated control of stem cell populations and alterations in their surrounding environment. Notch signaling is an important form of direct cell-cell communication involved in cell fate determination, stem cell potential and lineage commitment. The biological function of this pathway is critically context-dependent. Here we review the pro-differentiation role and tumor suppressing function of this pathway, as revealed by loss of function in keratinocytes and skin, downstream of p53 and in cross-connection with other determinants of stem cell potential and/or tumor formation, like p63 and Rho/CDC42 effectors. The possibility that Notch signaling elicits a duality of signals, involved in growth/differentiation control and cell survival will be discussed, in the context of novel approaches for cancer therapy.

Dotto, G. Paolo

2009-01-01

186

Exploring the Control of Spiral Waves and Spatiotemporal Chaos by Stochastic and Cross-Coupling Method  

NASA Astrophysics Data System (ADS)

In this paper, we propose the stochastic and unidirectional cross-coupled control method between two-layer excitable media to suppress the spiral waves and spatiotemporal chaos. Four types of the drive-response system in such two-layer excitable media are studied. By performing many simulations, results illustrate the spiral waves and spatiotemporal chaos can be controlled to the desired target states like the target waves and traveling waves. Patterns obtained are obviously different from those of the one-to-one coupling model. Based on the method proposed by Henry, we have carefully studied the generalized synchronization between the drive and response system with the stochastic and cross-connecting points via amplitude analysis and computing Poisson coefficient. Moreover, there also exists the frequency locking phenomenon.

Zhao, Rui; Pan, Wei; Xue, Yu

2013-09-01

187

Waste Isolation Pilot Plant Biennial Environmental Compliance Report  

SciTech Connect

This Biennial Environmental Compliance Report (BECR) documents environmental regulatory compliance at the Waste Isolation Pilot Plant (WIPP), a facility designed for the safe disposal of transuranic (TRU) radioactive waste, for the reporting period of April 1, 1998, to March 31, 2000. As required by the WIPP Land Withdrawal Act (LWA)(Public Law [Pub. L.] 102-579, and amended by Pub. L. 104-201), the BECR documents U.S. Department of Energy (DOE) Carlsbad Area Office's (hereinafter the ''CAO'') compliance with applicable environmental protection laws and regulations implemented by agencies of the federal government and the state of New Mexico. An issue was identified in the 1998 BECR relating to a potential cross-connection between the fire-water systems and the site domestic water system. While the CAO and its managing and operating contractor (hereinafter the ''MOC'') believe the site was always in compliance with cross-connection control requirements, hardware and procedural upgrades w ere implemented in March 1999 to strengthen its compliance posture. Further discussion of this issue is presented in section 30.2.2 herein. During this reporting period WIPP received two letters and a compliance order alleging violation of certain requirements outlined in section 9(a)(1) of the LWA. With the exception of one item, pending a final decision by the New Mexico Environment Department (NMED), all alleged violations have been resolved without the assessment of fines or penalties. Non-mixed TRU waste shipments began on March 26, 1999. Shipments continued through November 26, 1999, the effective date of the Waste Isolation Pilot Plant Hazardous Waste Facility Permit (NM4890139088-TSDF). No shipments regulated under the Hazardous Waste Facility Permit were received at WIPP during this BECR reporting period.

Westinghouse TRU Solutions

2000-12-01

188

The aerodynamic benefit of wing-wing interaction depends on stroke trajectory in flapping insect wings.  

PubMed

Flying insects may enhance their flight force production by contralateral wing interaction during dorsal stroke reversal ('clap-and-fling'). In this study, we explored the forces and moments due to clap-and-fling at various wing tip trajectories, employing a dynamically scaled electromechanical flapping device. The 17 tested bio-inspired kinematic patterns were identical in stroke amplitude, stroke frequency and angle of attack with respect to the horizontal stroke plane but varied in heaving motion. Clap-and-fling induced vertical force augmentation significantly decreased with increasing vertical force production averaged over the entire stroke cycle, whereas total force augmentation was independent from changes in force produced by a single wing. Vertical force augmentation was also largely independent of forces produced due to wing rotation at the stroke reversals, the sum of rotational circulation and wake capture force. We obtained maximum (17.4%) and minimum (1.4%) vertical force augmentation in two types of figure-eight stroke kinematics whereby rate and direction of heaving motion during fling may explain 58% of the variance in vertical force augmentation. This finding suggests that vertical wing motion distinctly alters the flow regime at the beginning of the downstroke. Using an analytical model, we determined pitching moments acting on an imaginary body of the flapping device from the measured time course of forces, the changes in length of the force vector's moment arm, the position of the centre of mass and body angle. The data show that pitching moments are largely independent from mean vertical force; however, clap-and-fling reinforces mean pitching moments by approximately 21%, compared to the moments produced by a single flapping wing. Pitching moments due to clap-and-fling significantly increase with increasing vertical force augmentation and produce nose-down moments in most of the tested patterns. The analytical model, however, shows that algebraic sign and magnitude of these moments may vary distinctly depending on both body angle and the distance between the wing hinge and the animal's centre of mass. Altogether, the data suggest that the benefit of clap-and-fling wing beat for vertical force enhancement and pitch balance may change with changing heaving motion and thus wing tip trajectory during manoeuvring flight. We hypothesize that these dependencies may have shaped the evolution of wing kinematics in insects that are limited by aerodynamic lift rather than by mechanical power of their flight musculature. PMID:17401119

Lehmann, Fritz-Olaf; Pick, Simon

2007-04-01

189

Multi-wavelength switching in SOAs  

NASA Astrophysics Data System (ADS)

Four-wave mixing (FWM) has potential to become an enabling technology of the future alloptical communication systems. FWM was used for laboratory demonstrations of multiplexing/demultiplexing in ultra- high speed time-division multiplexed (TDM) communication systems. This thesis focuses on FWM in wavelength division multiplexed (WDM) optical communication system. It was proposed to use FWM as all-optical, transparent, modulation format independent technique for partial or complete wavelength conversion in optical cross-connects. In this thesis, next generation integrated wavelength converters using multiple FWM in a single device are investigated. Potential applications are in future optical cross-connects (OXCs) with reduced complexity. The scope is this thesis is on multiple FWM in semiconductor optical amplifiers (SOAs) and its applicability as wavelength converter in WDM communication systems. A theoretical and experimental investigation of SOA saturation behavior under strong optical injection and a characterization of signal distortion through intersymbol interference (ISI) is included. Methods to minimize power penalties through ISI are outlined. It is concluded that for FWM using high pump power levels, ISI is minimized. Previously, this improvement was solely attributed to signal-to-noise ratio improvements only. The investigation of integrated FWM focuses on two configurations: a novel independently controlled FWM configuration and a multi-probe/single pump configuration. For both systems, limiting factors are investigated. Specifically, frequency response, FWM efficiency, signal-to-noise ratio, extinction ratio, crosstalk through FWM and crosstalk through cross gain modulation (XGM) are addressed. Strategies on improving FWM performance by minimizing these detrimental effects are given. Finally, dual channel independently controlled FWM in a single SOA is successfully demonstrated and limitations of the multi-probe/single pump configurations are pointed out. Based on this research, it is concluded that presently, FWM performance is limited by the current SOA devices. Up to now, SOA optimization for FWM application was performed through increase in amplifier length; systematic optimization procedures might lead to significant improvements in SOA performance. In this thesis, a physically based statespace representation of a SOA is introduced. Through this work, integrated SOA optimization strategies will become feasible.

Scholz, Christoph J.

190

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

191

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

192

Low Voltage Low Power Quadrature LC Oscillator Based on Back-gate Superharmonic Capacitive Coupling  

NASA Astrophysics Data System (ADS)

This work introduces a new low voltage low power superharmonic capacitive coupling quadrature LC oscillator (QLCO) made by coupling two identical cross-connected LC oscillators without tail transistor. In each of the core oscillators, the back-gate nodes of the cross-coupled NMOS pair and PMOS pair, acting as common mode nodes, have been connected directly. Then the core oscillators are coupled together via capacitive coupling of the PMOS common mode node in one of the core oscillators to the NMOS common mode node in the other core oscillator, and vice versa. Only capacitors are used for coupling of the two core oscillators and therefore no extra noise sources are imposed on the circuit. Operation of the proposed QLCO was investigated with simulation using a commercial 0.18 µm RF CMOS technology: it shows a power dissipation of 5.2 mW from a 0.6 V supply voltage. Since the proposed core oscillator has Complementary NMOS and PMOS cross coupled pairs, and capacitive coupling method will not introduce extra phase noise, so this circuit can operate with a low phase noise as low as -126.8 dBc/Hz at 1 MHz offset from center oscillation frequency of 2.4 GHz, as confirmed with simulation.

Ma, Minglin; Li, Zhijun

2013-09-01

193

Niche-specificity factors of a marine oil-degrading bacterium Alcanivorax borkumensis SK2.  

PubMed

Alcanivorax borkumensis strain SK2 is a cosmopolitan hydrocarbonoclastic marine bacterium, with a specialized metabolism adapted to the degradation of petroleum oil hydrocarbons. Transposon mutagenesis was used for functional genome analysis of Alcanivorax SK2 to reveal the genetic basis of other environmentally relevant phenotypes, such as biofilm formation, adaptation to UV exposure, and to growth at either low temperature or high salinity. Forty-eight relevant transposon mutants deficient in any one of these environmentally responsive functions were isolated, and the corresponding genes interrupted by the mini-Tn5 element were sequenced using inverse PCR. Several cross connections between different phenotypes (e.g. biofilm and UV stress; biofilm and UV and osmoadaptation) on signal transduction level have been revealed, pointing at complex and tightly controlled cellular interactions involving oxygen as a primary messenger and cyclic-di-GMP as a secondary messenger required for Alcanivorax responses to environmental stresses. These results provide insights into bacterial function in a complex marine environment. PMID:18557784

Sabirova, Julia S; Chernikova, Tatyana N; Timmis, Kenneth N; Golyshin, Peter N

2008-06-28

194

Variation of microorganism concentrations in urban stormwater runoff with land use and seasons.  

PubMed

Stormwater runoff samples were collected from outfalls draining small municipal separate storm sewer systems. The samples were collected from three different land use areas based on local designation (high-density residential, low-density residential and landscaped commercial). The concentrations of microorganisms in the stormwater runoff were found to be similar in magnitude to, but less variable than, those reported in the stormwater National Pollutant Discharge Elimination System (NPDES) database. Microorganism concentrations from high-density residential areas were higher than those associated with low-density residential and landscaped commercial areas. Since the outfalls were free of sanitary wastewater cross-connections, the major sources of microorganisms to the stormwater runoff were most likely from the feces of domestic animals and wildlife. Concentrations of microorganisms were significantly affected by the season during which the samples were collected. The lowest concentrations were observed during winter except for Staphylococcus aureus. The Pearson correlation coefficients among different indicators showed weak linear relationships and the relationships were statistically significant. However, the relationships between indicators and pathogens were poorly correlated and were not statistically significant, suggesting the use of indicators as evidence of the presence of pathogens is not appropriate. Further, the correlation between the concentration of the traditionally monitored indicators (total coliforms and fecal coliforms) and the suggested substitutes (enterococci and E. coli) is weak, but statistically significant, suggesting that historical time series will be only a qualitative indicator of impaired waters under the revised criteria for recreational water quality by the US EPA. PMID:16604843

Selvakumar, Ariamalar; Borst, Michael

2006-03-01

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

Electroabsorption and electrorefraction in InAs/GaAs and InAs/InP quantum dots  

NASA Astrophysics Data System (ADS)

Integrated optical cross connects and add-drop multiplexers require low loss polarization independent phase shifting elements. In a composite quantum well, a 0.46 mm phase shifter provides a ?/4 phase shift by combining the quantum confined Stark effect (QCSE) and carrier depletion effect. All-optical switching due to state filling effect is also experimentally investigated recently. We investigate whether the discrete energy levels and the high peak absorption in quantum dots (QDs) provide an opportunity for increasing the electrorefraction. The electrorefraction in strained InAs/GaAs and InAs/InP quantum dots (QDs) is explored using a numerical model based on the 4×4 Luttinger-Kohn Hamiltonian. The excitonic states are calculated by matrix diagonalization with plane-wave basis states. We observe that the QCSE sharply increases with the height of the QD and is also optimized for small radius QDs. The QCSE in pyramidal QDs is considerably larger than in squares or cylinders. We finally present large electrorefraction in cone shaped pyramidal QDs. State filling effect in QDs further resulted to an electrorefraction higher than an order of magnitude compared to that by QCSE for an acceptable waveguide absorption loss.

Prasanth, R.

2006-03-01

197

Fiber-channel trade-off for reducing collisions in slotted single-hop optical packet-switched networks  

NASA Astrophysics Data System (ADS)

The next-generation Internet should be based on high-capacity agile all-optical networks. A single-hop time-slotted all-optical packet-switched network is studied as a potential candidate for the ultra-high-speed next-generation all-optical metro network. This structure is composed of an all-optical wavelength-selective cross-connect core switch and a number of edge switches connected to the core switch in a star physical topology. Since optical packet switching (OPS) uses random medium access control, contention is the major problem for this network. Contention resolution techniques are used to resolve the contention. However, contention resolution hardware such as optical buffers and wavelength converters are expensive. In addition, optical buffers are complex and bulky. Therefore, we do not use contention resolution hardware in this network. Instead, we discuss and analyze the contention avoidance issue for such a network. Using more fibers and using additional wavelength channels to carry the same traffic are two schemes that can be used to reduce contention in OPS networks. We develop a cost model in order to optimize the number of fibers and additional channels required to achieve a given loss rate.

Ghaffar Pour Rahbar, Akbar; Yang, Oliver

2007-07-01

198

Review of Campylobacter spp. in drinking and environmental waters.  

PubMed

Consumption of contaminated drinking water is a significant cause of Campylobacter infections. Drinking water contamination is known to result from septic seepage and wastewater intrusion into non-disinfected sources of groundwater and occasionally from cross-connection into drinking water distribution systems. Wastewater effluents, farm animals and wild birds are the primary sources contributing human-infectious Campylobacters in environmental waters, impacting on recreational activities and drinking water sources. Culturing of Campylobacter entails time-consuming steps that often provide qualitative or semi-quantitative results. Viable but non-culturable forms due to environmental stress are not detected, and thus may result in false-negative assessments of Campylobacter risks from drinking and environmental waters. Molecular methods, especially quantitative PCR applications, are therefore important to use in the detection of environmental Campylobacter spp. Processing large volumes of water may be required to reach the desired sensitivity for either culture or molecular detection methods. In the future, applications of novel molecular techniques such as isothermal amplification and high-throughput sequencing applications are awaited to develop and become more affordable and practical in environmental Campylobacter research. The new technologies may change the knowledge on the prevalence and pathogenicity of the different Campylobacter species in the water environment. PMID:23810971

Pitkänen, Tarja

2013-06-26

199

Numerical and experimental study of a high port-density WDM optical packet switch architecture for data centers.  

PubMed

Data centers have to sustain the rapid growth of data traffic due to the increasing demand of bandwidth-hungry internet services. The current intra-data center fat tree topology causes communication bottlenecks in the server interaction process, power-hungry O-E-O conversions that limit the minimum latency and the power efficiency of these systems. In this paper we numerically and experimentally investigate an optical packet switch architecture with modular structure and highly distributed control that allow configuration times in the order of nanoseconds. Numerical results indicate that the candidate architecture scaled over 4000 ports, provides an overall throughput over 50 Tb/s and a packet loss rate below 10(-6) while assuring sub-microsecond latency. We present experimental results that demonstrate the feasibility of a 16x16 optical packet switch based on parallel 1x4 integrated optical cross-connect modules. Error-free operations can be achieved with 4 dB penalty while the overall energy consumption is of 66 pJ/b. Based on those results, we discuss feasibility to scale the architecture to a much larger port count. PMID:23388919

Di Lucente, S; Luo, J; Centelles, R Pueyo; Rohit, A; Zou, S; Williams, K A; Dorren, H J S; Calabretta, N

2013-01-14

200

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

201

Branching probe beams by fractional vortex dipoles: guiding vs. anti-guiding  

NASA Astrophysics Data System (ADS)

In this work we study the evolution and interaction of semi-infinite dark beams carrying edge-screw phase dislocations in self-focusing and self-defocusing local Kerr nonlinear media aiming to find appropriate conditions to control the process of fusion/crossing the dark beams in a way suitable for probe-beam cross-switching. We show that a quasi-infinite vortex dipole (dipole much longer than the background beam) evolves into a one-dimensional dark spatial soliton with vanishing transverse velocity. Single semi-infinite fractional dipole develops snake instability near the dark beam end. Depending on their phase profiles, four parallel semi-infinite fractional vortex dipoles aligned to initially form two dark stripes can evolve into two different `cross-connects' able to branch and route probe optical beams. Perpendicular probe beam propagation in the optically-induced guiding structures is modeled and analyzed with respect to the branching efficiency to respective virtual output channels for both self-focusing and self-defocusing conditions.

Maleshkov, G.; Hansinger, P.; Dimitrov, N.; Dreischuh, A.; Paulus, G. G.

2013-03-01

202

State-dependent computation using coupled recurrent networks.  

PubMed

Although conditional branching between possible behavioral states is a hallmark of intelligent behavior, very little is known about the neuronal mechanisms that support this processing. In a step toward solving this problem, we demonstrate by theoretical analysis and simulation how networks of richly interconnected neurons, such as those observed in the superficial layers of the neocortex, can embed reliable, robust finite state machines. We show how a multistable neuronal network containing a number of states can be created very simply by coupling two recurrent networks whose synaptic weights have been configured for soft winner-take-all (sWTA) performance. These two sWTAs have simple, homogeneous, locally recurrent connectivity except for a small fraction of recurrent cross-connections between them, which are used to embed the required states. This coupling between the maps allows the network to continue to express the current state even after the input that elicited that state is withdrawn. In addition, a small number of transition neurons implement the necessary input-driven transitions between the embedded states. We provide simple rules to systematically design and construct neuronal state machines of this kind. The significance of our finding is that it offers a method whereby the cortex could construct networks supporting a broad range of sophisticated processing by applying only small specializations to the same generic neuronal circuit. PMID:19431267

Rutishauser, Ueli; Douglas, Rodney J

2009-02-01

203

Broadband local service offerings using free-space optical links: a network business perspective  

NASA Astrophysics Data System (ADS)

12 This paper describes a promising optical wireless broadband technology that will provide low cost broadband services to the local access `last mile' market. This paper examines the application, advantages and limitations of utilizing Free Space Optical Communications (FSOC) systems for broadband access markets. The service markets that would fully utilize FSOC technologies include metropolitan areas, BLECs (multi- tenant dwellings/business apartments), campuses, industrial parks and `pole-to-hole' neighborhood deployments. This paper will identify weather dependent link availability as being the primary consideration in defining and selecting suitable locations for FSOC-based systems. Link availability in turn determines link range, type of service, and the need for transmission diversity. This paper will describe the implications of telecom `five nines' last-mile access availability and its effect on the transparent integration of FSOC technologies into the existing fiber optic networks. This paper will also describe propagation losses and link budget requirements for broadband FSOC-based local service. During adverse weather conditions, stand-alone, FSOC-based optical wireless links typically offer path lengths of less than 200 meters while still meeting the `five nines' availability criteria. This paper will also consider `availability limited' services. These services may prove to be attractive to customers who are willing to accept broadband service on an `as available basis'. The use of availability-enhancing transmission diversity and the use of intelligent `roof-top' routing and optical wireless cross connects between buildings will also be discussed.

Britz, David M.; Dodley, J. P.; Barnickel, D. J.

2001-02-01

204

Optical switch based on thermocapillarity  

NASA Astrophysics Data System (ADS)

Space-division optical switches are essential for the protection, optical cross-connects (OXCs), and optical add/drop multiplexers (OADMs) needed in future fiber-optic communication networks. For applications in these areas, we proposed a thermocapillarity switch called oil-latching interfacial-tension variation effect (OLIVE) switch. An OLIVE switch is a micro-mechanical optical switch fabricated on planar lightwave circuits (PLC) using micro-electro-mechanical systems (MEMS) technology. It consists of a crossing waveguide that has a groove at each crossing point and a pair of microheaters. The groove is partially filled with the refractive-index-matching liquid, and optical signals are switched according to the liquid's position in the groove, i.e., whether it is passing straight through the groove or reflecting at the sidewall of the groove. The liquid is driven by thermocapillarity and latched by capillarity. Using the total internal reflection to switch the optical path, the OLIVE switch exhibits excellent optical characteristics, such as high transparency (insertion loss: < 2 dB), high extinction ratio (> 50 dB), and low crosstalk (< -50 dB). Moreover, since this switch has a simple structure and bi-stability, it has wide variety of applications in wavelength division multiplexing (WDM) networks.

Sakata, Tomomi; Makihara, Mitsuhiro; Togo, Hiroyoshi; Shimokawa, Fusao; Kaneko, Kazumasa

2001-11-01

205

Metro Optical Networks for Homeland Security  

NASA Astrophysics Data System (ADS)

Metro optical networks provide an enticing opportunity for strengthening homeland security. Many existing and emerging fiber-optic networks can be adapted for enhanced security applications. Applications include airports, theme parks, sports venues, and border surveillance systems. Here real-time high-quality video and captured images can be collected, transported, processed, and stored for security applications. Video and data collection are important also at correctional facilities, courts, infrastructure (e.g., dams, bridges, railroads, reservoirs, power stations), and at military and other government locations. The scaling of DWDM-based networks allows vast amounts of data to be collected and transported including biometric features of individuals at security check points. Here applications will be discussed along with potential solutions and challenges. Examples of solutions to these problems are given. This includes a discussion of metropolitan aggregation platforms for voice, video, and data that are SONET compliant for use in SONET networks and the use of DWDM technology for scaling and transporting a variety of protocols. Element management software allows not only network status monitoring, but also provides optimized allocation of network resources through the use of optical switches or electrical cross connects.

Bechtel, James H.

206

Multiple thermoregulatory effectors with independent central controls.  

PubMed

This review first considers how mammalian body temperature regulation evolved, and how the brain's responses to thermoregulatory challenges are likely to be organised differently from the way an engineer would design them. This is because thermoregulatory effector mechanisms would have evolved one at a time, with each being superimposed on pre-existing mechanisms. There may be no functional need for the final ensemble of control loops to be coordinated by neural cross-connections: appropriate thermal thresholds would solve the problem sufficiently. Investigations first into thermoregulatory behaviours and later into unconscious thermoregulatory mechanisms (autonomic and shivering) have led investigators to the realisation that multiple control loops exist in the brain, with each effector system apparently regulated by its own central temperature sensors. This theme is developed with reference to data on four temperature-regulated neural outflows that have been studied on anaesthetized rats under standard conditions in the authors' laboratory. Direct comparisons were made between the behaviour of sympathetic nerves supplying the tail vasculature, vessels in the proximal hairy skin, interscapular brown adipose tissue (BAT) and fusimotor fibres to hind limb muscle. All four outflows were activated by cooling the skin, and all were silenced by neuronal inhibition in the medullary raphé. Their thermal thresholds were quite different, however, as were their relative responsiveness to core temperature. This was ranked as: tail > back skin > BAT > fusimotor. These and other data indicate that the four thermoeffector outflows are driven by separate neural pathways, each regulated by independent brain temperature sensors. PMID:19949811

McAllen, Robin M; Tanaka, Mutsumi; Ootsuka, Yoichiro; McKinley, Michael J

2009-12-01

207

Holding time aware differentiated protection method for survivable waveband switching optical networks  

NASA Astrophysics Data System (ADS)

Due to the number of wavelengths in fibers increasing, the transmission ports consumed in optical cross-connect (OXC) are greatly enhanced. To reduce the complexity and the cost of OXC, waveband switching technology is proposed. At the same time, since an optical channel carries a lot of traffic, its failure may lead to a huge data loss. Therefore, survivability in waveband switching (WBS) optical networks is important. Previous work for survivable WBS optical networks did not consider the holding time of connection request. However, in a practical network, the different connection requests generally have different holding times. This fact affects the network performances. In this paper, we propose a new method, holding time aware differentiated protection (HTADP), to provide the survivability for single-link failure in WBS optical networks. In HTADP, if the holding time of a connection request is smaller than the preset threshold, the protection path will not be assigned for saving network resources. In addition, we design a waveband integrated auxiliary graph for HTADP to well support the routing and waveband assignment. Simulation results demonstrate that HTADP not only saves more transmission ports but also is able to obtain lower blocking probability compared with previous method.

Hou, Weigang; Guo, Lei; Li, Yan; Wu, Tengfei

2011-12-01

208

Detecting river pollution using fluorescence spectrophotometry: case studies from the Ouseburn, NE England.  

PubMed

Recent advances in fluorescence spectrophotometry enable the analysis of river dissolved organic matter. We investigate the potential of detecting sewage pollution in a small, urbanised catchment. Downstream sampling highlighted a summer maximum in tryptophan fluorescence intensity during low flow. No correlation is observed between ammonia and tryptophan fluorescence intensity. In contrast, two sewage related point-pollution events had both high tryptophan fluorescence intensity and ammonia, suggesting that the summer tryptophan increase does not original from foul sewage. Sewage inputs to the river were therefore monitored at summer base flow. This demonstrated that > 10% of the rivers' discharge is provided by sewerage inputs and that these inputs could be grouped by their fluorescence and ammonia properties: (1) 'clean' storm waters with low ammonia and tryptophan intensity (2) 'grey' waters with high tryptophan intensity and low ammonia concentration, and (3) 'foul' waters with high tryptophan intensity and ammonia concentration. All three types of sewerage input occurred irrespective of flow conditions,suggesting that sewerage cross connections are occurring. PMID:12683983

Baker, Andy; Inverarity, Roger; Charlton, Martin; Richmond, Susie

2003-01-01

209

Memory-driven movements in limb apraxia: is there evidence for impaired communication between the dorsal and the ventral streams?  

PubMed

Memory-driven reaching and grasping movements were analysed in patients with left cerebral hemispheric damage and impaired gesture imitation. The dorsal and ventral streams of the visual pathway model of Milner and Goodale (Milner and Goodale, The Visual Brain in Action, 1995) are thought to operate relatively independently. However, cross-connections between the areas of each pathway are likely to enable interactions essential for higher-level praxis. Apraxic errors such as seen in gesture imitation can possibly be understood as arising from a disconnection of the two visual pathways. If the integrated action of the perceptual and visuomotor systems in patients with apraxia is compromised, then we would expect to find indications of impaired motor programming and misreaching in these patients when making movements driven by stored representations. Such a pattern, however, was not found in our sample of apraxic patients. Patients with limb apraxia produced normal movement kinematics and normal end-point accuracy when making memory-driven reaching movements with or without visual guidance of movement. Furthermore, perceptual information about object size and object distance were incorporated as normal in memory-driven grasping movements of these patients. PMID:11516447

Ietswaart, M; Carey, D P; Della Sala, S; Dijkhuizen, R S

2001-01-01

210

Fission products behavior in molten fluoride salts: Speciation of La3+ and Cs+ in melts containing oxide ions  

NASA Astrophysics Data System (ADS)

In this paper we address the effects of fission products on the speciation in molten fluoride salts. Numerous systems with cross-connections have been investigated in order to better identify the influence of CsF in a fluoride melt containing rare earth and oxides : LaF3-AF (A = Li, Na, K, Rb and Cs), LaF3-LiF-CsF, LaF3-LiF-CaF2, LaF3-LiF-CaO, LaF3-LiF-CaO-CsF. In this goal, we performed high temperature NMR experiments and followed in situ the evolution of 19F, 23Na, 85Rb, 133Cs and 139La NMR chemical shifts. In LaF3-AF-CsF and LaF3-AF-CaF2 systems, the coordination number of lanthanum cation ranges from 6 to 8 depending on the LaF3 concentration and on the polarizability of the other cations. The addition of oxide (CaO) in the latter mixtures leads to the formation of lanthanum oxyfluoride species that precipitate in LaOF when CaO concentration is increased. The addition of CsF to LaF3-LiF-CaO yields to a displacement of the dissolved versus precipitated LaOF proportion.

Rollet, Anne-Laure; Veron, Emmanuel; Bessada, Catherine

2012-10-01

211

Performance of a practical gain controlling approach for erbium-doped fiber amplifier  

NASA Astrophysics Data System (ADS)

Wavelength routing and reconfigurable cross connects are emerging concepts for optical multiwavelength telecommunication networks. They provide more efficient usage of the network resources, as individual wavelength channels can be added or dropped from the wavelength multiplex. However, problems arise with the erbium-doped fiber amplifiers (EDFAs), whose gain is dependent on the input power level. If the gain of the EDFA is not by some means controlled, transient effects will occur due to the EDFA's slow gain dynamics. In this paper a simple device for controlling the gain of the EDFA is studied. The gain- controlling scheme is based on a fast pump laser control. Part of the total input power to the amplifier is detected by the gain controlling circuitry, which then compensates for the changing gain by adjusting the pump laser power. In the study, transient effects due to changing number of channels in an EDFA are measured. The response time and the transient suppression of the gain-controlling device are verified through measurements. The effect of the amplifier gain tilt is also studied. A comparison against other proposed gain-controlling schemes is done.

Soederlund, Mikko J.; Tammela, Simo K.

2000-04-01

212

Flexible and simple link design for long-haul transmission taking real span-length variations into account  

NASA Astrophysics Data System (ADS)

The pressure on prices per bit and distance in operator networks requires an ongoing reduction of costs. In todays optical transport networks typical transparent transmission lengths are in the order of about 400 to 600 km. Then costly electrical 3R-regeneration is required. One way to deal with this cost-driver is to introduce ultra long haul (ULH) transparent WDM systems which are able to cover transmission length of e.g. up to 2000 km and thus decreasing the number of regenerative transponders. However, to maintain the flexibility of the network to add and drop traffic at required locations the use of optical add drop multiplexers (OADMs) or optical cross connects (OXCs) is mandatory in these systems, particularly for pan-European but even for European national networks. The design of such ULH-networks has to deal with a vast number of issues, in particular the physical layer design has to be very flexible and to allow for different optimization and adjustment schemes. In this paper based on computer simulations we will compare different approaches to reduce the design complexity of 10 Gbit/s ULH systems taking into account environmental constraints like availability of housing stations for different target distances.

Breuer, Dirk; Hanik, Norbert

2004-05-01

213

Micro-actuator with extended analog deflection at low drive voltage  

NASA Astrophysics Data System (ADS)

Electrostatic Micro-actuators are being increasingly used for a wide variety of applications such as spatial light modulators, scanning mirrors, optical cross connects, micro-valves, and others. Usually the electrical forces operate in one direction and are balanced by a mechanical spring. The resulting deflection is then either defined by a mechanical stop, or it is only a meta-stable equilibrium position: at an additional external force or deflection it will snap to a different position, frequently again defined by a mechanical stop. This issue is well known and is often called 'pull-in'. In the often used parallel-plate capacitor actuator, the instability already begins at a deflection of only on third of the original capacitor plate separation. For safety reasons and due to the steep response-curve one can only use an even smaller fraction of the mechanically possible movement. This means, that the gap below the actuator has to be designed very much larger than the required maximum deflection. To get the pre-described force and deflection, a much higher voltage is needed than for potential smaller gap widths. The useable range of deflection for many types of micro-actuators can be extended without the penalty of large drive voltage or low shock resistivity, by employing springs with steeper-than-linear restoring force. Alternatively, the voltage needed for a given range of deflection may be reduced. This paper shows the benefits and how to design and dimension these types of springs.

Dürr, Peter; Gehner, Andreas; Schmidt, Jan; Kunze, Detlef; Wagner, Michael; Lakner, Hubert

2006-01-01

214

Greywater recycling systems in Germany--results, experiences and guidelines.  

PubMed

Although Germany is not considered a water-poor country, there exist regional differences in water supply and consumption. During the past 15 years, the greywater aspect has been dealt with in Germany with a greater interest and variable success. In addition to an increased environmental awareness, water costs also play an important role in increasing the demand for advanced greywater treatment plants nstalled in buildings. Under favourable conditions, the amortisation costs usually lie between 5 and 7 years. Systems that have been extensively tried and tested and have been shown to be most reliable are those employing an advanced biological treatment followed by an UV disinfection. Systems based on membrane technology are being developed and researched intensively in Germany for municipal wastewater treatment. However, so far they play no role in greywater recycling. Greywater systems operating under low energy and maintenance requirements without the use of chemicals are mostly favoured. In Germany, greywater recycling systems should be registered at the Health Office in order to guarantee that no cross-connections exist with the drinking water network and that pipes are labelled according to regulations. The hygienic requirements for recycled greywater, which is primarily used for toilet flushing, are oriented towards the EU-Guidelines for Bathing Waters. The use of recycled greywater for irrigation purposes is minor. As to the use of recycled water for laundry, the first promising investigation results are now available. PMID:16104423

Nolde, E

2005-01-01

215

Network performance and integrity enhancement with optical path layer technologies  

NASA Astrophysics Data System (ADS)

Path layer technologies will play a key role in the development of a powerful and failure resilient B-ISDN. So far, they have been based on electrical technologies. This paper highlights WDM/FDM techniques and demonstrates that optical paths can greatly enhance the path layer capability and, therefore, the network performance. It is also shown that effective network failure restoration can be achieved with optical paths. The applicability of the Wavelength Path (WP) technique to global area networks is revealed by comparing different optical path realization techniques. WP's are applied to the national backbone network example to evaluate the require number of wavelength, and to identify optical path concept: the Virtual Wavelength Path (VWP). In the VWP scheme, wavelengths are assigned on a link-by-link basis. In other words, the wavelength assigned to a wavelength path has only local significance. Significant benefits of the VWP such as the simplified path accommodation design within a transmission facility network and the reduced number of wavelengths needed, are elucidated. An optical cross-connect node architecture that enables the VWP's is also proposed. The architecture allows the VWP concept to be realized with commercially available optical technologies. The optical path layer concept proposed in this paper exploits and consolidate the layered transport network architecture and optical technologies, and will open up new opportunities for creating a B-ISDN that is bandwidth abundant and has a high degree of integrity.

Sato, Ken-Ichi; Okamoto, Satoru; Hadama, Hisaya

1994-01-01

216

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

217

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

218

Multicast Routing and Wavelength Assignment with Shared Protection in Multi-Fiber WDM Mesh Networks: Optimal and Heuristic Solutions  

NASA Astrophysics Data System (ADS)

While the problem of multicast routing and wavelength assignment (MC-RWA) in optical wavelength division multiplexing (WDM) networks has been investigated, relatively few researchers have considered network survivability for multicasting. This paper provides an optimization framework to solve the MC-RWA problem in a multi-fiber WDM network that can recover from a single-link failure with shared protection. Using the light-tree (LT) concept to support multicast sessions, we consider two protection strategies that try to reduce service disruptions after a link failure. The first strategy, called light-tree reconfiguration (LTR) protection, computes a new multicast LT for each session affected by the failure. The second strategy, called optical branch reconfiguration (OBR) protection, tries to restore a logical connection between two adjacent multicast members disconnected by the failure. To solve the MC-RWA problem optimally, we propose an integer linear programming (ILP) formulation that minimizes the total number of fibers required for both working and backup traffic. The ILP formulation takes into account joint routing of working and backup traffic, the wavelength continuity constraint, and the limited splitting degree of multicast-capable optical cross-connects (MC-OXCs). After showing some numerical results for optimal solutions, we propose heuristic algorithms that reduce the computational complexity and make the problem solvable for large networks. Numerical results suggest that the proposed heuristic yields efficient solutions compared to optimal solutions obtained from exact optimization.

Woradit, Kampol; Guyot, Matthieu; Vanichchanunt, Pisit; Saengudomlert, Poompat; Wuttisittikulkij, Lunchakorn

219

Telecommunications administration standard  

SciTech Connect

The administration of telecommunications is critical to proper maintenance and operation. The intent is to be able to properly support telecommunications for the distribution of all information within a building/campus. This standard will provide a uniform administration scheme that is independent of applications, and will establish guidelines for owners, installers, designers and contractors. This standard will accommodate existing building wiring, new building wiring and outside plant wiring. Existing buildings may not readily adapt to all applications of this standard, but the requirement for telecommunications administration is applicable to all buildings. Administration of the telecommunications infrastructure includes documentation (labels, records, drawings, reports, and work orders) of cables, termination hardware, patching and cross-connect facilities, telecommunications rooms, and other telecommunications spaces (conduits, grounding, and cable pathways are documented by Facilities Engineering). The investment in properly documenting telecommunications is a worthwhile effort. It is necessary to adhere to these standards to ensure quality and efficiency for the operation and maintenance of the telecommunications infrastructure for Sandia National Laboratories.

Gustwiller, K.D. [GTE Customer Networks, Albuquerque, NM (United States)

1996-05-01

220

Earth and Space Science in the new NRC "Conceptual Framework for New Science Education Standards"  

NASA Astrophysics Data System (ADS)

The National Academy of Sciences has begun the process of creating a new set of K-12 science education standards. At the start of 2011 the National Research Council will release its “Conceptual Framework for New Science Education Standards,” which provides a vision for creating new and improved set of guidelines for the teaching of science. The Earth & Space content was formulated by an Earth & Space Design Team, consisting of the authors of this abstract. The “Framework,” funded by the Carnegie Foundation of New York, places a greater emphasis on the practices of learning and on major cross-cutting themes that run through the four content areas: Earth and Space Science, Physical Science, Life Science, and Engineering and Technology. One aim of the framework is to inspire a set of science standards that are more fundamental, cross-connecting, and less fact-oriented. Compared to previous efforts, the Earth & Space Science component places greater emphasis on a systems approach to Earth Science, on the interrelationships between humans and Earth systems, and on the science surrounding and connected to climate change. The organization Achieve, Inc., has already begun to use this “Framework” for the creation of a set of national K-12 science education standards.

Wysession, M. E.; Duggan-Haas, D. A.; Linneman, S. R.; Pyle, E.; Schatz, D.

2010-12-01

221

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

222

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

223

An iml3-chl4 heterodimer links the core centromere to factors required for accurate chromosome segregation.  

PubMed

Accurate segregation of genetic material in eukaryotes relies on the kinetochore, a multiprotein complex that connects centromeric DNA with microtubules. In yeast and humans, two proteins-Mif2/CENP-C and Chl4/CNEP-N-interact with specialized centromeric nucleosomes and establish distinct but cross-connecting axes of chromatin-microtubule linkage. Proteins recruited by Chl4/CENP-N include a subset that regulates chromosome transmission fidelity. We show that Chl4 and a conserved member of this subset, Iml3, both from Saccharomyces cerevisiae, form a stable protein complex that interacts with Mif2 and Sgo1. We have determined the structures of an Iml3 homodimer and an Iml3-Chl4 heterodimer, which suggest a mechanism for regulating the assembly of this functional axis of the kinetochore. We propose that at the core centromere, the Chl4-Iml3 complex participates in recruiting factors, such as Sgo1, that influence sister chromatid cohesion and encourage sister kinetochore biorientation. PMID:24075991

Hinshaw, Stephen M; Harrison, Stephen C

2013-09-26

224

Quantifying Urban Water Subsidies with Hydrological Tracers of Domestic Water  

NASA Astrophysics Data System (ADS)

Connections between urban hydrological systems and human water infrastructure are well established. Interactions between these systems occur at a wide range of scales, from large inter-basin transfers to individual leaking pipes. However, much of the interest in these connections arises from practical considerations, for example, substantially altered in-stream flow or the presence/absence of sewage in surface water systems. Less recognized is that in smaller urban catchments, daily water flux through human water distribution systems is often much larger than low flow surface water flux from the catchment. As infrastructure ages and cross-connections grow, transfers from the substantial human fluxes to the catchment will increasingly subsidize urban water budgets. Tools for quantifying the contribution of this subsidy to urban hydrological systems can clarify both practical questions for urban managers and our understanding of flow generation in catchments. Stream water chemistry from a multi-year sampling campaign in Nine Mile Run (Pittsburgh, PA) is used to examine potential hydrological tracers of human domestic water. In particular, we examine the use of fluoride added in precise quantities as a dental health supplement as a tracer of human domestic water (e.g., drinking and waste water). While fluoride is not necessarily a conservative tracer, equilibrium reactions governing fluoride solubility generally require substantially higher cationic concentrations than those observed in surface water chemistry. Further, during periods where human subsidies dominate (e.g., water line breaks or hydrant flushes discharging to the stream) fluoride concentrations generally approach the concentration added to domestic water. We use multiple modeling approaches to demonstrate the appropriateness of fluoride as a tracer, infer contributions of human domestic water to the hydrologic budget, and explore fluoride dynamics in the Nine Mile Run basin. A fluoride tracer is particularly exciting due to applicability in a large number of urban systems fluoridating drinking waters and due to robust, high-frequency measurement capacity via off-the-shelf drinking water treatment technologies.

Bain, D. J.; Sikora, M. T.; Wozniak, E.; Fisher, K. R.; Carr, J.; Elliott, E. M.

2011-12-01

225

Technologies for optical networking in Nx160-Gbit/s DWDM networks  

NASA Astrophysics Data System (ADS)

Future multi-terabit/s optical core networks require optical technologies capable of managing ultra-high bit rate OTDM/DWDM (optical time division multiplexing/dense wavelength division multiplexing) channels at 160 Gbit/s or higher bit rates. The key functionalities in ultra-high speed network nodes are all-optical wavelength conversion, 3R-regeneration and demultiplexing of OTDM signals. Advanced optical networking techniques (optical add-drop multiplexing and optical routing) are studied in simulations and their performance evaluated considering 160 Gbit/s OTDM/DWDM channels. Performance comparison results for both OADM (optical add-drop multiplexer) and OXC (optical cross-connect) node networking functionalities are shown considering different technologies: semiconductor-optical-amplifier-based symmetric Mach-Zehnder interferometers (SOA-MZI) for wavelength conversion, signal regeneration and demultiplexing, electroabsorption-modulator-based demultiplexers, and wavelength converters based on four-wave mixing in dispersion-shifted fiber. The simulation results show that the SOA-MZI is a promising technology for all-optical signal processing in network nodes mainly due to its signal regeneration capability. At ultra-high bit rates, however, the relaxation time of SOAs considerably limits the operation. A solution to mitigate this problem is to use a differential scheme at the input of the device. Error-free wavelength conversion, signal regeneration and demultiplexing of 160 Gbit/s OTDM signals employing a SOA-MZI with a differential scheme is demonstrated by means of simulations. Furthermore, the parameters of this architecture are optimized to obtain the best performance for each optical networking functionality in OADM and OXC network nodes.

Ramos, Francisco; Schulze, Karsten; Martinez, Jose Manuel; Marti, Javier; Llorente, Roberto; Clavero, Raquel

2003-08-01

226

Protein-like fluorescence intensity as a possible tool for determining river water quality  

NASA Astrophysics Data System (ADS)

The results of a comparison between chemical water quality determinants and river water fluorescence on the River Tyne, NE England, demonstrate that tryptophan-like fluorescence intensity shows statistically significant relationships between nitrate, phosphate, ammonia, biochemical oxygen demand (BOD) and dissolved oxygen. Tryptophan-like fluorescence intensity at the 280 nm excitation/350 nm emission wavelength fluorescence centre correlates with both phosphate (r = 0.80) and nitrate (r = 0.87), whereas tryptophan-like fluorescence intensity at the 220 nm excitation/350 nm emission wavelength centre correlates with BOD (r = 0.85), ammonia (r = 0.70) and dissolved oxygen (r = -0.65). The strongest correlations are between tryptophan-like fluorescence intensity and nitrate and phosphate, which in the Tyne catchment derive predominantly from point and diffuse source sewage inputs. The correlation between BOD and the tryptophan-like fluorescence intensity suggests that this fluorescence centre is related to the bioavailable or labile dissolved organic matter pool. The weakest correlations are observed between tryptophan-like fluorescence intensity and ammonia concentration and dissolved oxygen. The weaker correlation with ammonia is due to removal of the ammonia signal by wastewater treatment, and that with dissolved oxygen due to the natural aeration of the river such that this is not a good indicator of water quality. The observed correlations only hold true when treated sewage, sewerage overflows or cross connections, or agricultural organic pollutants dominate the water quality - this is not true for two sites where airport deicer (propylene glycol, which is non-fluorescent) or landfill leachate (which contains high concentrations of humic and fulvic-like fluorescent DOM) dominate the dissolved organic matter in the river. Mean annual tryptophan-like fluorescence intensity agrees well with the General Water Quality Assessment as determined by the England and Wales environmental regulators, the Environment Agency.

Baker, Andy; Inverarity, Roger

2004-10-01

227

Effect of Emergency Argon on FCF Operational Incidents  

SciTech Connect

The following report presents analyses of operational incidents which are considered in the safety analysis of the FCF argon cell and the effect that the operability of the emergency argon system has on the course of these incidents. The purpose of this study is to determine if the emergency argon system makes a significant difference in ameliorating the course of these incidents. Six incidents were considered. The following three incidents were analyzed. These are: 1. Cooling failing on 2. Vacuum Pump Failing on 3. Argon Supplies Failing on. In the remaining three incidents, the emergency argon supply would have no effect on the course of these transients since it would not come on during these incidents. The transients are 1. Loss of Cooling 2. Loss of power (Differs from above by startup delay till the Diesel Generators come on.) 3. Cell rupture due to an earthquake or other cause. The analyses of the first three incidents are reported on in the next three sections. This report is issued realizing the control parameters used may not be optimum, and additional modeling must be done to model the inertia of refrigeration system, but the major conclusion concerning the need for the emergency argon system is still valid. The timing of some events may change with a more accurate model but the differences between the transients with and without emergency argon will remain the same. Some of the parameters assumed in the analyses are Makeup argon supply, 18 cfm, initiates when pressure is = -6 iwg., shuts off when pressure is = -3.1 iwg. 170,000 ft3 supply. Min 1/7th always available, can be cross connected to HFEF argon supply dewar. Emergency argon supply, 900 cfm, initiates when pressure is = -8 iwg. shuts off when pressure is =-4 iwg. reservoir 220 ft3, refilled when tank farm pressure reduces to 1050 psi which is about 110 ft3.

Charles Solbrig

2011-12-01

228

Wavelength band switching in multigranular all-optical networks  

NASA Astrophysics Data System (ADS)

In this paper, we address the problem of wavelength band switching (WBS) in multi-granular, wavelength division multiplexing optical networks. The purpose of WBS is to reduce the increasing control complexity and port numbers in ordinary optical cross-connects. We classify the WBS problem into eight variations and then focus on one of them, wherein there are a fixed number of wavebands in each fiber, each with a fixed number of wavelengths and in fact, consisting of a fixed set of wavelengths. We develop an integer linear programming (ILP) model, which for a given set of lightpath requests, determines the routes and assigns wavelengths for the lightpaths so as to minimize the number of ports needed. Our model is more generic than existing solutions, as it takes into account the grouping of lightpaths having different sources and destinations and hence maximizes the benefits of WBS. Since the subproblem of minimizing the port count with WBS is NP-complete, we also develop and compare two heuristic algorithms: namely Waveband Oblivious optimal Routing and Wavelength assignment (or WBO-RWA), and Balanced Path routing with Heavy-Traffic first waveband assignment (or BPHT). For small networks, our results indicate that the performance of the BPHT heuristic is quite close to that achievable using the ILP. For larger networks, the ILP model is no longer feasible, but BPHT can perform considerably better than WBO-RWA. Our results also provide valuable insights into the effect of wavelength band granularity on the performance of WBS algorithms, as well as the tradeoffs between the wavelength-hop and the port count.

Cao, Xiaojun; Xiong, Yizhi; Anand, Vishal; Qiao, Chunming

2002-07-01

229

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

2013-05-20

230

Regulation of excitation-contraction coupling in mouse cardiac myocytes: integrative analysis with mathematical modelling  

PubMed Central

Background The cardiomyocyte is a prime example of inherently complex biological system with inter- and cross-connected feedback loops in signalling, forming the basic properties of intracellular homeostasis. Functional properties of cells and tissues have been studied e.g. with powerful tools of genetic engineering, combined with extensive experimentation. While this approach provides accurate information about the physiology at the endpoint, complementary methods, such as mathematical modelling, can provide more detailed information about the processes that have lead to the endpoint phenotype. Results In order to gain novel mechanistic information of the excitation-contraction coupling in normal myocytes and to analyze sophisticated genetically engineered heart models, we have built a mathematical model of a mouse ventricular myocyte. In addition to the fundamental components of membrane excitation, calcium signalling and contraction, our integrated model includes the calcium-calmodulin-dependent enzyme cascade and the regulation it imposes on the proteins involved in excitation-contraction coupling. With the model, we investigate the effects of three genetic modifications that interfere with calcium signalling: 1) ablation of phospholamban, 2) disruption of the regulation of L-type calcium channels by calcium-calmodulin-dependent kinase II (CaMK) and 3) overexpression of CaMK. We show that the key features of the experimental phenotypes involve physiological compensatory and autoregulatory mechanisms that bring the system to a state closer to the original wild-type phenotype in all transgenic models. A drastic phenotype was found when the genetic modification disrupts the regulatory signalling system itself, i.e. the CaMK overexpression model. Conclusion The novel features of the presented cardiomyocyte model enable accurate description of excitation-contraction coupling. The model is thus an applicable tool for further studies of both normal and defective cellular physiology. We propose that integrative modelling as in the present work is a valuable complement to experiments in understanding the causality within complex biological systems such as cardiac myocytes.

Koivumaki, Jussi T; Korhonen, Topi; Takalo, Jouni; Weckstrom, Matti; Tavi, Pasi

2009-01-01

231

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

232

Novel packet-loss free reconfiguration scheme for GMPLS optical networks  

NASA Astrophysics Data System (ADS)

Reconfigurable optical network, the way of the future, can encounter serious packet loss problem during optical level reconfiguration. This paper presents a novel buffering scheme for GMPLS optical networks that minimizes packet loss during reconfiguration of optical nodes, consisting of both a reconfigurable optical cross-connects (OXCs), or an optical add-drop multiplexers (OADMs), and a packet-capable layer-two switch. In this scheme, buffering takes place whenever an optical path is altered due to either a node reconfiguration or protection/restoration. Packets are buffered in a distributed manner starting from the first O/E/O-capable node before the reconfigured optical node all the way to the ingress node, if needed. In the worst-case scenario, where the path is all-optical or buffers are full along the path, all incoming packets are buffered at the ingress node, or the edge router. Buffering is carried out at layer two so that the interruption of service is kept at a minimum (less than 50ms, if possible). Furthermore, if buffers are overflowed, packets dropping will be carried out in accordance with the QoS levels, which further ensure that QoS of the network is maintained. It is shown by both analysis and simulation methods that this scheme performs quite well on either a general local area network, such as the UMBC WDM optical testbed, or the MCI backbone network. It is also cost-effective in that, even at the worst-case scenario, the required buffer is quite small.

Guo, Aihua; Chen, Wenlu; Chen, Wei; Zhu, Zhonghua; Chen, Yung J.

2002-09-01

233

A review of outbreaks of waterborne disease associated with ships: evidence for risk management.  

PubMed Central

OBJECTIVE: The organization of water supply to and on ships differs considerably from that of water supply on land. Risks of contamination can arise from source water at the port or during loading, storage, or distribution on the ship. The purpose of this article is to review documented outbreaks of waterborne diseases associated with passenger, cargo, fishing, and naval ships to identify contributing factors so that similar outbreaks can be prevented in the future. METHODS: The authors reviewed 21 reported outbreaks of waterborne diseases associated with ships. For each outbreak, data on pathogens/toxins, type of ship, factors contributing to outbreaks, mortality and morbidity, and remedial action are presented. RESULTS: The findings of this review show that the majority of reported outbreaks were associated with passenger ships and that more than 6,400 people were affected. Waterborne outbreaks due to Enterotoxigenic Escherichia coli, noroviruses, Salmonella spp, Shigella sp, Cryptosporidium sp, and Giardia lamblia occurred on ships. Enterotoxigenic E. coli was the pathogen most frequently associated with outbreaks. One outbreak of chemical water poisoning also occurred on a ship. Risk factors included contaminated port water, inadequate treatment, improper loading techniques, poor design and maintenance of storage tanks, ingress of contamination during repair and maintenance, cross-connections, back siphonage, and insufficient residual disinfectant. CONCLUSIONS: Waterborne disease outbreaks on ships can be prevented. The factors contributing to outbreaks emphasize the need for hygienic handling of water along the supply chain from source to consumption. A comprehensive approach to water safety on ships is essential. This may be achieved by the adoption of Water Safety Plans that cover design, construction, operation, and routine inspection and maintenance.

Rooney, Roisin M.; Bartram, Jamie K.; Cramer, Elaine H.; Mantha, Stacey; Nichols, Gordon; Suraj, Rohini; Todd, Ewen C. D.

2004-01-01

234

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

235

Optical networks security: a failure management framework  

NASA Astrophysics Data System (ADS)

Network security is becoming a very sensitive and important topic for equipment manufacturers and network operators. In transparent optical networks, security is even more complex since the optical signals are not regenerated as in opaque networks and, therefore, the faults and attacks at the physical layer are more difficult to detect and isolate without significantly affecting the overall network performance. In this paper we define Failure Management as the prevention, detection, and reaction against failures. Failures are defined as the interruptions of the normal functioning of the network and comprise faults (accidental interruptions) as well as attacks (intentional interruptions which can be performed by service disruption or eavesdropping). Our work deals with a solution to detection of failures in transparent networks. For this purpose we have extended a Fault Location algorithm developed for opaque optical networks to be used in transparent networks and be able to also locate attacks. The proposed algorithm is called Transparent Failure Location Algorithm (TFLA). The first part of the extension is based on the study of other optical network elements such as Optical Add/Drop Multiplexers (OADMs), Optical Cross-Connects (OXCs), wavelength converters, Optical Line Terminators, etc. The vulnerability of these elements depends on their architecture and/or fabrication technology and, therefore, different attacks can be considered. A classification of these components based on the masking and alarming properties is proposed. The second part of the extension is based on the monitoring equipment that may be available in transparent networks. The TFLA was applied for the case of a transparent ring of the Pan-European network.

Mas, Carmen; Tomkos, Ioannis; Tonguz, Ozan K.

2003-08-01

236

Efficient optically switched metro Ethernet  

NASA Astrophysics Data System (ADS)

With the overwhelming success of Ethernet technology in local access networks (LANs), owing to its ease of management and its much lower line rate cost, there has been a continuous effort in migrating Ethernet technology into metro-area networks (MANs) and wide-area networks (WANs). However, current Ethernet technology has to overcome the scalability and reliability deficiencies in order to be recognized as a viable MAN/WAN technology. Recently these concerns are being addressed under the framework of Generalized-MPLS (GMPLS) and its traffic-engineering (TE) intelligence. In this paper we propose an optical Ethernet solution viable for MAN/WAN based on the concept of a reconfigurable Ethernet node, integrating reconfigurable optical cross-connects (OXCs) with traditional Ethernet switches. We subsequently proposed a dynamic TE scheme that utilizes both the simplicity of all-optical switching and the flexibility of optical-electrical-optical (OEO) traffic grooming realized by the proposed optical Ethernet node. We showed through simulations that with our proposed TE scheme, the number of OEO transceivers needed by such an optical Ethernet node is only about 20% of a fully-populated one in the extreme case (very high load) and about only 10% in normal load conditions, without degrading the performance. This actually implies a tremendous cost saving on Ethernet OEO transceivers, and on the other hand indicates that a highly efficient and scalable MAN/WAN Ethernet network system could be well achieved by using Ethernet switches of only modest switching capacity (as legacy Ethernet switches have) along with reconfigurable OXCs. To demonstrate and test our proposed ideas we have built a GMPLS testbed using MEMS-based optical cross-bar switches and legacy Gigabit Ethernet switches. The testbed consists of three core nodes and six edge nodes. Performance experiments have been conducted on the testbed as well.

Guo, Aihua; Chen, Yung J.

2006-10-01

237

Fanconi anemia core complex gene promoters harbor conserved transcription regulatory elements.  

PubMed

The Fanconi anemia (FA) gene family is a recent addition to the complex network of proteins that respond to and repair certain types of DNA damage in the human genome. Since little is known about the regulation of this novel group of genes at the DNA level, we characterized the promoters of the eight genes (FANCA, B, C, E, F, G, L and M) that compose the FA core complex. The promoters of these genes show the characteristic attributes of housekeeping genes, such as a high GC content and CpG islands, a lack of TATA boxes and a low conservation. The promoters functioned in a monodirectional way and were, in their most active regions, comparable in strength to the SV40 promoter in our reporter plasmids. They were also marked by a distinctive transcriptional start site (TSS). In the 5' region of each promoter, we identified a region that was able to negatively regulate the promoter activity in HeLa and HEK 293 cells in isolation. The central and 3' regions of the promoter sequences harbor binding sites for several common and rare transcription factors, including STAT, SMAD, E2F, AP1 and YY1, which indicates that there may be cross-connections to several established regulatory pathways. Electrophoretic mobility shift assays and siRNA experiments confirmed the shared regulatory responses between the prominent members of the TGF-? and JAK/STAT pathways and members of the FA core complex. Although the promoters are not well conserved, they share region and sequence specific regulatory motifs and transcription factor binding sites (TBFs), and we identified a bi-partite nature to these promoters. These results support a hypothesis based on the co-evolution of the FA core complex genes that was expanded to include their promoters. PMID:21826217

Meier, Daniel; Schindler, Detlev

2011-08-03

238

James Clerk Maxwell Prize for Plasma Physics: The Physics of Magnetic Reconnection and Associated Particle Acceleration  

NASA Astrophysics Data System (ADS)

Solar and stellar flares, substorms in the Earth's magnetosphere, and disruptions in laboratory fusion experiments are driven by the explosive release of magnetic energy through the process of magnetic reconnection. During reconnection oppositely directed magnetic fields break and cross-connect. The resulting magnetic slingshots convert magnetic energy into high velocity flows, thermal energy and energetic particles. A major scientific challenge has been the multi-scale nature of the problem: a narrow boundary layer, ``the dissipation region,'' breaks field lines and controls the release of energy in a macroscale system. Significant progress has been made on fundamental questions such as how magnetic energy is released so quickly and why the release occurs as an explosion. At the small spatial scales of the dissipation region the motion of electrons and ions decouples, the MHD description breaks down and whistler and kinetic Alfven dynamics drives reconnection. The dispersive property of these waves leads to fast reconnection, insensitive to system size and weakly dependent on dissipation, consistent with observations. The evidence for these waves during reconnection in the magnetosphere and the laboratory is compelling. The role of turbulence within the dissipation region in the form of ``secondary islands'' or as a source of anomalous resistivity continues to be explored. A large fraction of the magnetic energy released during reconnection appears in the form of energetic electrons and protons -- up to 50% or more during solar flares. The mechanism for energetic particle production during magnetic reconnection has remained a mystery. Models based on reconnection at a single large x-line are incapable of producing the large numbers of energetic electrons seen in observations. Scenarios based on particle acceleration in a multi-x-line environment are more promising. In such models a link between the energy gain of electrons and the magnetic energy released, a requirement to explain the observations, has been established. The talk will review key observational data and emphasize basic physical principles to introduce the topic to the non-specialist.[4pt] Thanks to the many colleagues who have contributed to this work. This work was supported by DOE, NASA and NSF.

Drake, James

2010-11-01

239

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

240

Analysis of elemental concentration using ICP-AES and pathogen indicator in drinking water of Qasim Abad, District Rawalpindi, Pakistan.  

PubMed

The present study was conducted to investigate drinking water quality (groundwater) from water samples taken from Qasim Abad, a locality of approximately 5,000 population, situated between twin cities Rawalpindi and Islamabad in Pakistan. The main sources of drinking water in this area are water bores which are dug upto the depth of 250-280 ft in almost every house. The study consists of the determination of physico-chemical properties, trace metals, heavy metals, rare earth elements and microbiological quality of drinking water. The data showed the variation of the investigated parameters in samples as follows: pH 6.75 to 8.70, electrical conductivity 540 to 855 ?S/cm, total dissolved solids 325.46 to 515.23 ppm and dissolved oxygen 1.50 to 5.64 mg/L which are within the WHO guidelines for drinking water quality. The water samples were analysed for 30 elements (aluminium, iron, magnesium, manganese, silicon, zinc, molybdenum, titanium, chromium, nickel, tungsten, silver, arsenic, boron, barium, beryllium, cadmium, cobalt, copper, gallium, mercury, lanthanum, niobium, neodymium, lead, selenium, samarium, tin, vanadium and zirconium) by using inductively coupled plasma atomic emission spectroscopy. The organic contamination was detected in terms of most probable number (MPN) of faecal coliforms. Overall, elemental levels were lower than the recommended values but three water bores (B-1, B-6, B-7) had higher values of iron (1.6, 2.206, 0.65 ppm), two water bores (B-1, B-6) had higher values of aluminium (0.95, 1.92 ppm), respectively, and molybdenum was higher by 0.01 ppm only in one water bore (B-11). The total number of coliforms present in water samples was found to be within the prescribed limit of the WHO except for 5 out of 11 bore water samples (B-2, B-3, B-4, B-8, B-11), which were found in the range 5-35 MPN/100 mL, a consequence of infiltration of contaminated water (sewage) through cross connection, leakage points and back siphoning. PMID:22544071

Sehar, Shama; Naz, Iffat; Ali, Naeem; Ahmed, Safia

2012-04-29

241

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

242

Simulation of external contamination into water distribution systems through defects in pipes  

NASA Astrophysics Data System (ADS)

Water quality can be defined as a set of properties (physical, biological and chemical) that determine its suitability for human use or for its role in the biosphere. In this contribution we focus on the possible impact on water distribution systems quality of external contaminant fluids entering through defects in pipes. The physical integrity of the distribution system is a primary barrier against the entry of external contaminants and the loss in quality of the treated drinking water, but this integrity can be broken. Deficiencies in physical and hydraulic integrity can lead into water losses, but also into the influx of contaminants through pipes walls, either through breaks coming from external subsoil waters, or via cross connections coming from sewerage or other facilities. These external contamination events (the so called pathogen intrusion phenomenon) can act as a source of income by introducing nutrients and sediments as well as decreasing disinfectant concentrations within the distribution system, thus resulting in a degradation of the distribution water quality. The objective of this contribution is to represent this pathogen intrusion phenomenon. The combination of presence of defects in the infrastructures (equipment failure), suppression and back-siphonage and lack of disinfection is the cause of propagation of contamination in the clean current of water. Intrusion of pathogenic microorganisms has been studied and registered even in well maintained services. Therefore, this situation can happen when negative pressure conditions are achieved in the systems combined with the presence of defects in pipes nearby the suppression. A simulation of the process by which the external fluids can come inside pipes across their defects in a steady-state situation will be considered, by using different techniques to get such a successful modeling, combining numerical and experimental simulations. The proposed modeling process is based on experimental and computational simulations. An analysis of the intrusion behavior considering hydrodynamic and transportation of pollutant phenomena has been developed, comparing the influence of the turbulence consideration and the agreement of both computational and experimental results. This paper is focused on the analysis of such external intrusion phenomenon, the relationship between the income flow and the pressure inside the pipe, depending on the characteristics of the defect and the pressure level, as well as the effect on the water quality of the income substances dispersion. Two different experiments have been developed. In order to represent the intrusion phenomenon in steady state, two suitable assemblies have been implemented in the laboratory. In a lower order of pressures a Venturi tube has been used for generating the depression. In a higher level of pressures, a pumping system has been used. The defect on the pipe has been simulated by a circular hole, and the dispersion of pollutant has been considered by means of salinity as a conservative contaminant. The simulated scenarios of different suppressions can vary from 0.001 to 0.7 bars. The prototypes are also simulated by numerical modeling in two and three dimensions using Computational Fluid Dynamics techniques. For this purpose Fluent 6.3™ has been used, which displays the fields of hydrodynamic components and salinity. After doing a proper calibration process, the contrast made between models will allows us to establish the foundation for further pathogen intrusion simulations in the distribution system. Different turbulent models based on turbulent viscosity and different boundary conditions will also be considered. The agreement between experimental and computational models will be analyzed, and the differences between series of results will be compared, validating thus the use of computational models for representing the pathogen intrusion problem. By both, mathematical and physical models, it is intended to have a better knowledge of quantities that can not be measured, such as velocity fields, aspects of t

López, P. A.; Mora, J. J.; García, F. J.; López, G.

2009-04-01

243

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