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Sample records for sucker rod string

  1. Mechanical performance of fiberglass sucker-rod strings

    SciTech Connect

    Tripp, H.A.

    1988-08-01

    The natural frequencies of fiberglass sucker-rod strings can be calculated by treating the rod strings as modified spring/mass vibration systems. The ratio of the pumping-unit operating speed to the rod-string natural frequency can then be used as a basis for understanding fiberglass-rod performance and for predicting downhole pump stroke lengths.

  2. Numerical modelling of longitudinal vibrations of a sucker rod string

    NASA Astrophysics Data System (ADS)

    Shardakov, I. N.; Wasserman, I. N.

    2010-03-01

    A new technique for analyzing the dynamic behavior of a sucker rod string used in the oil well industry is presented. The main difficulty in the numerical calculation of the examined structure is a multivalued velocity—force relation determined by Coulomb's friction and by loads generated during operation of pump valves. Both the monotonic and nonmonotonic velocity—force relations are considered. A quasi-variational inequality formulation of the problem is proposed. The solution of the inequality amounts to finding the minimum of a convex nonsmooth functional at each time step by means of the Newmark difference time scheme, successive iterations and finite element discretization. The problem of functional minimization is reduced to construction of a sequence of smooth nonlinear programming problems by introducing the auxiliary variables and applying the augmented Lagrangian method. The proposed approach is used to study the longitudinal vibrations of sucker rod strings under near-real conditions. In such systems the most commonly occurring vibration modes are the stick-slip vibrations and the vibrations with natural force excited twice a cycle. The nonmonotonic character of the friction law leads to intensification of these vibrations. In the case of nonmonotonic friction law the stick-slip vibrations can occur even under the action of constant external forces.

  3. A method for designing fiberglass sucker-rod strings with API RP 11L

    SciTech Connect

    Jennings, J.W.; Laine, R.E. )

    1991-02-01

    This paper presents a method for using the API recommended practice for the design of sucker-rod pumping systems with fiberglass composite rod strings. The API method is useful for obtaining quick, approximate, preliminary design calculations. Equations for calculating all the composite material factors needed in the API calculations are given.

  4. Sucker rod guide

    SciTech Connect

    White, R.C.

    1988-10-25

    This patent describes an improved guide for use in a string of sucker rods for reciprocation in a tubing string in a borehole, the sucker rods having threaded male ends, the guide comprising: an elongated upright cylindrical member of external diameter less than the internal diameter of tubing in which it is to be used, the member having sucker rod receiving female threaded openings at the upper and lower ends, the threaded openings being coaxial of the member cylindrical axis whereby the member may be positioned in a string of sucker rods, and including a plurality of spaced-apart parallel sided slots within the member, each slot being of semi-circular configuration and of depth greater than the radius and less than the diameter of the cylindrical member, the sidewalls of each slot being parallel to and equally spaced from a plane of the member cylindrical axis; the member having an axle bore therein for each of the slots, the axle bores being parallel and spaced apart from each other, a plane of the axis of each bore being perpendicular the member cylindrical axis and the axis of each bore being displaced away from the member cylindrical axis; an axle received in each axle bore; and a wheel received on each axle the diameter of each wheel being approximately the diameter of the cylindrical member, the periphery of each wheel extending beyond the member cylindrical wall whereby the wheels are positioned to engage and roll on the internal cylindrical surface of tubing, the planes of adjacent slots in the member being rotationally displaced from each other, a portion of each wheel extending beyond the cylindrical surface of the member, the opposed portion of each wheel being within the confines of the member cylindrical surface whereby each wheel can contact a tubing wall at only one point on its cylindrical surface.

  5. Sucker rod coupling

    SciTech Connect

    Klyne, A.A.

    1986-11-11

    An anti-friction sucker rod coupling is described for connecting a pair of sucker rods and centralizing them in a tubing string, comprising: an elongate, rigid, substantially cylindrical body member, each end of the body member forming means for threadably connecting the body member with a sucker rod. The body member further forms a transversely extending, substantially diametric, generally vertical slot extending therethrough. The body member further forms a pin bore, such pin bore extending transversely through the body member so as to intersect the slot substantially perpendicularly; a wheel member positioned within the slot to rotate in a generally vertical plane. The wheel member has a portion thereof extending beyond the periphery of the body member to engage the inner surface of the tubing string and centralize the coupling; and a pin mounted in the pin bore and supporting member thereon, whereby the wheel member is rotatable within the slot; the wheel member having sufficient clearance between its side surfaces and the wall surfaces of the slot, when the wheel member is centered in the slot on the pin, whereby the wheel member may shift along the pin to assist in ejecting sand and oil from the slot.

  6. Sucker rod guide

    SciTech Connect

    Edwards, B.J.; Starks, J.A.

    1989-08-22

    This patent describes a sucker rod guide for mounting on a sucker rod and spacing the sucker rod from the tubing in an oil well. The guide comprising a generally cylindrically-shaped, extruded, ultra-high density polyethylene body having a substantially smooth outside surface; a longitudinal bore provided centrally of the body. The bore having a smaller diameter than the diameter of the sucker rod; a plurality of grooves provided in circumferential relationship in the bore; and a tapered slot extending longitudinally through the body from the outside surface to the bore. The tapered slot further comprising a slot mouth located at the outside surface and a slot throat spaced from the slot mouth. The slot throat lying adjacent to the sucker rod bore and wherein the slot throat is wider than the slot mouth for mounting the sucker rod guide on the sucker rod.

  7. Cost-effective methods for designing and operating fiberglass sucker rod strings

    SciTech Connect

    Jacobs, G.H.

    1986-01-01

    This paper describes procedures used by Amoco Production Company in a West Texas district to maximize the life of more than 200 fiberglass rod strings in service at depths between 5000 and 8000 ft. The paper describes rod string design methods, operating practices, and failure analyses for two major manufacturers' rods. Emphasis has been placed on showing procedures used in designing fiberglass rod strings for cost effective installation and for operating so as to minimize the number of rod string failures and, consequently, rod string operating costs. Actual cases histories are used to illustrate the reduction in failure frequency which results from proper rod string design, operating practices, and failure analysis.

  8. Modeling and simulation performance of sucker rod beam pump

    SciTech Connect

    Aditsania, Annisa; Rahmawati, Silvy Dewi Sukarno, Pudjo; Soewono, Edy

    2015-09-30

    Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption proved non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.

  9. Modeling and simulation performance of sucker rod beam pump

    NASA Astrophysics Data System (ADS)

    Aditsania, Annisa; Rahmawati, Silvy Dewi; Sukarno, Pudjo; Soewono, Edy

    2015-09-01

    Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption proved non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.

  10. 1987 Sucker rod tables

    SciTech Connect

    Not Available

    1987-03-01

    This reference identifies manufacturers qualified to produce API sucker rods and related equipment, lists chemical and mechanical properties of the various types of rods and provides dimensional characteristics. In addition, similar information is given for non-API products such as fiberglass and hollow rods.

  11. Guide for rotating sucker rods

    SciTech Connect

    Harrel, R.D.

    1986-11-04

    This patent describes an improved guide for use in a string of sucker rods rotated in a tubing string in a borehole, the sucker rods having threaded male ends, the guide comprising: an elongated upright solid cylindrical coupling body of external diameter less than the internal diameter of tubing in which it is to be used; a pair of spaced apart axle holders positioned in three recess; an axle received in each recess in the coupling body, the axis of each axle being parallel and spaced from the body longitudinal axis; a roller rotatably received on each axle, the periphery of each roller extending exteriorly of the external cylindrical surface of the coupling body; and means to retain each of the holders in the coupling body recess.

  12. Improved model for sucker rod pumping

    SciTech Connect

    Doty, D.R.; Schmidt, Z.

    1981-01-01

    An improved model for predicting the behavior of sucker rod pumping installations is presented. This model incorporates the dynamics of the liquid columns as well as the sucker rod string through a system of partial differential equations. The system of equations is solved by a modified method of characteristics on a digital computer. The model predicts the polished rod and pump dynamometer cards and incorporates the effects of liquid inertia and viscosity. It is capable of simulating a wide variety of pumping conditions where liquid physical properties are important. The information predicted by the model is useful in the design and operation of sucker rod pumping installations. Refs.

  13. An improved model for sucker rod pumping

    SciTech Connect

    Doty, D.R.; Schmidt, Z.

    1983-02-01

    An improved model for predicting the behavior of sucker rod pumping installations is presented. This model incorporates the dynamics of the liquid columns as well as the sucker rod string through a system of partial differential equations. This system of equations is solved by a modified method of characteristics on a digital computer. The model predicts the polished-rod and pump dynamometer cards and incorporates the effects of liquid inertia and viscosity. The model is capable of simulating a wide variety of pumping conditions for which liquid physical properties are important. The information predicted by the model is useful in the design and operation of sucker rod pumping installations.

  14. Class D sucker rods

    SciTech Connect

    Woodings, R. T.

    1984-10-23

    It has been found that API Class D sucker rods can be made inexpensively from low-alloy, low-cost steel by following a suitable induction-normalizing process and using a suitable steel to which there has been added 0.07 to 0.15 percent of vanadium.

  15. Sucker rod construction

    SciTech Connect

    Anderson, R.A.; Goodman, J.L.; Tickle, J.D.; Liskey, A.K.

    1987-03-31

    A sucker rod construction is described comprising: a connector member being formed to define a rod receptacle having a closed axially inner end and an open axially outer end, the rod receptacle having axially spaced, tapered annular surfaces, a cylindrical fiberglass rod having an end having an outer surface being received within the rod receptacle through the outer end and cooperating therewith to define an annular chamber between the outer surface of the end of the rod and the tapered annular surfaces, and a bonding means positioned in the annular chamber for bonding to the outer surface of the end of the rod to confront the tapered annular surfaces, each annular surface having an angle of taper with respect to the outer surface of the fiberglass rod, and each angle of taper being progressively and uniformly less toward the open end by an amount between one and one-half degrees and two degrees, inclusive, and a collet connected to the connector member adjacent the open axially outer end of the rod receptacle and having an axial bore therethrough retaining the end of the rod in coaxial position within the rod receptacle.

  16. Sucker rod centralizer

    SciTech Connect

    Rivas, O.; Newski, A.

    1989-10-03

    This patent describes a device for centralizing at least one sucker rod within a production pipe downhole in a well and for reducing frictional forces between the pipe and at least one sucker rod. It comprises an elongate, substantially cylindrical body member having a longitudinal axis, a plurality of slots within the member and a rotatable member mounted within each slot, each of the plurality of slots has its major dimension along a first axis parallel to the longitudinal axis of the body member and is oriented with respect to the other seats so as to form a helicoidal array for maximizing the total surface contact area between the rotatable members and the pipe and for decreasing the forces acting on each rotatable member.

  17. Flexible sucker rod unit

    SciTech Connect

    Allen, L.F.

    1987-02-03

    This patent describes a deep well having: a. an education tube with an inside diameter extending from the surface of the earth to far below the surface, b. a reciprocating pump housing attached to the bottom of the education tube, c. pump jack means at the surface for reciprocating the pump, d. a light sucker rod connected to the pump jack means and extending into the education tube, and e. a series of heavy sinker bars having a large cross sectional area in the education tube connecting the light sucker rod to the pump; f. an improved integral metal flexible rod unit interconnecting the sinker bars comprising in combination with the above: g. a coupling on each end of the integral metal flexible rod unit connecting the flexible rod unit to the contiguous sinker bar, h. a segment which is flexible as compared to the sinker bars connecting one of the couplings to i. an integral metal bearing adjacent to the other of the couplings, the bearing having j. a cylindrical surface with k. a diameter i. only slightly smaller than the inside diameter of the education tube thereby forming a sliding fit therewith, and ii. greater than the diameter of any other portion of the flexible rod unit and the sinker bar, and l. grooves in the cylindrical surface for the passage of fluid between in the education tube around the bearing.

  18. Sucker rod pump

    SciTech Connect

    Brewer, J.R.

    1992-04-14

    This patent describes a subsurface well pump, it comprises: a working barrel; a plunger which reciprocates along the vertical axis within the working barrel between an upper and lower position; a rod connected to the plunger and extending to a means for providing reciprocating force; a well string extending from the top of the working barrel to the surface; an outlet check valve which permits flow to exit the working barrel into the well string and does not permit flow to exit the well string into the working barrel; and an inlet check valve which permits flow into the working barrel from outside of the subsurface pump, the inlet check valve being above the top position of the plunger, the inlet check valve having a cross sectional flow area about equal to or greater than the horizontal cross sectional area of the working barrel, and the inlet check valve being a hinged flapper valve.

  19. Method of cleaning and inhibiting sucker rod corrosion

    SciTech Connect

    Ford, M. B.; Griffin, J. B.

    1985-01-22

    Method of cleaning tubular goods, especially sucker rods, and inhibiting the sucker rods against corrosion as the rod string is being withdrawn from a borehole. The method is carried out by the provision of an enclosure which is attached to the upper end of a cased borehole. The upper end of the sucker rod string is extended axially through the enclosure as the rod string is withdrawn from the casing. A medial length of the rod string is engaged by a resilient packer device which wipes the rod clean of well fluids and loose debris. The rod string is next cleaned within a second chamber by impacting the outer surface thereof with an abrasive substance. The rod surface is again cleaned of any residual material. The rod is then moved through another chamber where corrosion inhibitor is applied to the external surface of the rod. As each treated joint of rod is withdrawn from the enclosure, the rod joints are sequentially unscrewed and suitably stacked, where the rods are protected from the elements, as well as being protected when the rods are subsequently made up into a rod string as the rod is replaced into a borehole.

  20. Improved designs reduce sucker-rod pumping costs

    SciTech Connect

    Takacs, G.

    1996-10-07

    Pumping mode selection, optimum counterbalance determination, and rod string design are factors that can reduce operational costs and improve sucker-rod pumping operations. To maximize profits from sucker-rod pumped wells, designs must aim at technically and economically optimum conditions. Assessment of surface and downhole energy losses are basic considerations for improving system efficiency. It is important to properly select the pumping mode, such as the combination of plunger size, pumping speed, stroke length, and rod taper design. The best pumping mode maximizes lifting efficiency and, at the same time, reduces prime-mover power requirements and electrical costs. Surface equipment operational efficiency can be improved with optimum counterbalancing of the pumping unit, and top achieve an ideal sucker-rod pumping system, a tapered rod string must have a proper mechanical design. The paper discusses rod pumping, downhole energy losses, surface losses, optimum efficiency, mode selection, counterbalancing, minimizing the cyclic load factor, and rod string design.

  1. Analysis of sucker rod and sinkerbar failures

    SciTech Connect

    Waggoner, J.R.; Buchheit, R.G.

    1993-03-01

    This report presents results of a study of performance and failures of the sucker rod/sinkerbar string used in beam-pumping operations through metallography, finite element analysis, and failure data collection. Metallography showed that the microstructure of the steel bar stock needs to be considered to improve the fatigue resistance of the sucker rod strings. The current specification based on tensile strength, or yield strength, may not be appropriate since failure occurs because of fatigue and not yielding, and tensile strength is not always a good measure of fatigue resistance. Finite element analysis of the threaded connection quantitatively assesses the coupling designs under various loading conditions. Subcritical fractures in metallography are also suggested by calculated stress distribution in threaded coupling. Failure data illustrates both magnitude and frequency of failures, as well as categorizing the suspected cause of failure. Application of the results in each of these project areas is expected to yield improved choice of metal bar stock, thread design, and make-up practices which can significantly reduce the frequency of sucker rod failures. Sucker rod failures today are not inherent in the process, but can be minimized through the application of new technology and observation of common-sense practices.

  2. Rod coupling for oil well sucker rods and the like

    SciTech Connect

    Bowers, R.

    1986-07-29

    A coupling is described for joining solid reciprocating sucker rods to form a rod string in a well pump or the like comprising a unitary metal sleeve having an axial threaded bore and an irregular outer surface, and a homogeneous and non-fibrous coating on the sleeve over the outer surface providing an externally substantially cylindrical coupling, the coating comprising a flexible and abrasive resistant thermoplastic hydrourethane polymer formed on the irregular outer surface of the sleeve while in the molten state.

  3. Sucker rod assembly and method

    SciTech Connect

    Pagan, A.J.

    1986-07-01

    An improved sucker rod assembly is described comprising, in combination: a. a sucker rod; and b. a pair of fittings secured to opposite ends of the rod, each fitting including: i. a rigid elongated casing having interior surfaces defining an open front end and cavity extending rearwardly from the open front end in which cavity one end of the sucker rod is disposed, the side portions of the interior surfaces being contoured to define, with the side portions of the sucker rod end a single, annular elongated tapered wedge-shaped space; and ii. anchoring means filling the space and bonding to the side portions of the rod end to lock the rod end in place, the anchoring means having a narrower diameter at the front end thereof than at about the rear end thereof and being generally frusto-conical, the anchoring means comprising a plurality of separate rigid inserts, the interior surfaces of which collectively define a central elongated passageway in which the rod end is received, the interior surfaces of the inserts being tightly bonded to the side portions of the rod, and the inserts being bonded to each other along the contact lines therebetween to form a unitary structure.

  4. Interpretation of calculated forces on sucker rods

    SciTech Connect

    Lea, J.F.; Pattillo, P.D. ); Studenmund, W.R. )

    1995-02-01

    The analysis of working loads in a sucker rod string during a pumping cycle has received substantial coverage in the petroleum literature. These load predictions have tended to focus on mechanical design considerations such as excess load and fatigue prediction. In contrast, the current study addresses the issues of buckling associated with working axial/pressure loads in an attempt to clarify the means of both predicting buckling and minimizing its effects. The study begins with a review of the static loads acting near the pump, and proceeds to a discussion of how these loads relate to the tendency of a rod string to buckle on the downstroke. Critical to this discussion is the concept of effective tension. Definition of the effective tension leads to the application of this concept to sinker bar design as a means of mitigating the buckling tendency of a rod string. Key points are reinforced by illustrative examples.

  5. What operators say about fiberglass sucker rods

    SciTech Connect

    Bleakley, W.B.

    1984-11-01

    This article presents the results of an informal survey of oil producing companies and one design engineering firm in the Permian Basin about the use and performance of fiberglass sucker rods in sucker rod pumps.

  6. 13. SOUTHEAST TO SUCKER ROD WORK BENCH AND WOODEN SUCKER ...

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

    13. SOUTHEAST TO SUCKER ROD WORK BENCH AND WOODEN SUCKER ROD STORAGE RACKS ALONG EAST WALL OF FACTORY INTERIOR. AT THIS BENCH WORKERS RIVETED THREADED WROUGHT IRON CONNECTORS TO THE ENDS OF 20' LONG WOODEN SUCKER RODS (THE RODS WHICH EXTEND DOWNWARD IN THE WELL FROM THE GROUND SURFACE TO PISTON DISPLACEMENT PUMPS WHICH ACTUALLY ELEVATE WATER TO THE SURFACE). ROZNOR HEATER AT THE FAR RIGHT WAS ADDED CIRCA 1960. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

  7. Application of fiberglass sucker rods

    SciTech Connect

    Gibbs, S.G. )

    1991-05-01

    Fiberglass sucker rods are assuming a place in artificial-lift technology. This paper briefly describes the manufacturing process and gives some design and operational hints for practical applications. It also describes some mathematical modeling modifications needed for fiberglass wave-equation design programs.

  8. Designing a sucker-rod pumping system for maximum efficiency

    SciTech Connect

    Gault, R.H.

    1987-11-01

    Consideration of the energy requirements in the design of a sucker-rod pumping system is very important. Examples are given that detail how the use of the largest possible pump with the lightest, strongest rod string and special-geometry units can provide a substantial energy reduction.

  9. Designing a sucker rod pumping system for maximum efficiency

    SciTech Connect

    Gault, R.H.

    1985-01-01

    Consideration of the energy requirements in the design of a sucker rod pumping system is very important. Examples are given which detail how the use of the largest possible pump with the lightest, strongest, rod string and special geometry units can provide a substantial energy reduction.

  10. Fiberglass sucker rods - a futuristic solution to today's problem wells

    SciTech Connect

    Treadway, R.B.; Focazio, K.R.

    1981-01-01

    A new fiberglass sucker rod design was developed, which incorporated many new and major modifications to correct the problems that had plagued the previous rod. This paper documents the success of these rods in depths ranging from 5,000'-10,000', and production ranges of 150 - 700 barrels of fluid per day. In addition, Amoco had also installed over fifty strings of fiberglass rods in their other four West Texas and Eastern New Mexico districts, and several are being evaluated in East Texas and on the Gulf Coast. At the present time, all of these additional installations show the same success as those reported in this paper. The changes in the manufacturing process, the use of a computer program for performance prediction, and the development of a new load range diagram are also discussed. Final data indicate that, when designed and installed properly, fiberglass sucker rods are a viable, economic, and often preferable alternative to steel sucker rods.

  11. Wear simulation of sucker rod couplings

    SciTech Connect

    Schumacher, W.J. )

    1991-09-01

    This paper reports that sucker rod strings are devices used to actuate pumps located at the bottom of oil wells. The individual rods are connected together by threaded couplings. Since the couplings have a larger diameter than the rods, they sometimes contact the inside diameter of the tubing during the up and down pumping cycle. Usually, this is not problem unless buckling occurs in the downstroke; however, this can lead to accelerated wear of the coupling and tubing. In nonvertical wells (offset, deviated, or slanted), the contact is more severe and rapid wear takes place. Couplings are more easily replaced during shutdowns; it is very important to minimize wear to tubing since it is virtually impossible to replace. TRIBONIC 20, an iron-based alloy containing approximately 13% Mn, 5% Si, 5.5% Cr, and 5% Ni, was laboratory evaluated to determine whether or not it could solve the sucker rod coupling-production tubing wear problem. The alloy demonstrated outstanding wear resistance both to itself and in protecting type 1019 steel.

  12. Sucker rod coupling with protective coating

    SciTech Connect

    Gray, K.W.

    1990-03-06

    This patent describes a coupling adapted to be used in a string of oil well sucker rods. It comprises: a cylindrical metallic cuff having a radial face at each end and internal threads for its entire length, having a resinous coating about 0.040 inches thick bonded over all of the external surfaces, the resinous coating is fused onto the metal. This patent describes a second coupling adapted to be used in a string of oil well sucker rods. It comprises: a cylindrical metallic cuff having a radial face at each end and internal threads for its entire length, having a resinous coating bonded over all of the external surfaces, the resinous coating is fused onto the metal, a distal plug within one end of the cuff, the distal plug snugly fitting the threads of one end and covering all internal surfaces, and an eyelet plug on the other end. The eyelet plug extending within the other end and covering the threads of that end and all internal surfaces.

  13. Oil well sucker rod safety block

    SciTech Connect

    McDaniel, D. L.

    1984-11-20

    A fail-safe knock-off block for use during the repair or servicing of oil well surface pumping equipment involving a longitudinally slotted pipe capped at each end by top and bottom pipe segments which are held in place concentric to the slotted pipe by a resilient handle. An inner handle on the slotted pipe allows the concentric caps to be rotated axially from an open position to a closed position, thus encircling the polish rod. The weight of the sucker rod string on the end caps during use compresses the end caps and resilient handle thus locking the safety block such that it can neither open nor come off the well head.

  14. Attachment for sucker rod depth adjustment

    SciTech Connect

    Collins, N.D.

    1992-04-07

    This patent describes a surface unit of an oil well pumping system, having a walking beam, a suspended carrier bar and an interconnected sucker rod assembly for stroking a reciprocating down-hole pump. It comprises a cross bar having a centrally located passage therein for the sucker rod assembly and adapted to be transversely supported by the carrier bar; a depth adjusting bar, having a centrally located passage therein for the sucker rod assembly, positioned at a selected fixed dimension above and parallel to the cross bar and adapted to operatively support the sucker rod assembly; clamping means for fixing the sucker rod relative to the depth adjusting bar; and hydraulically extendable means supportively connecting the depth adjusting bar to the cross bar on at least each side of the carrier bar for adjusting the selected fixed dimension and maintaining the adjustment during operation.

  15. Enhancement of fiberglass sucker-rod design is offered

    SciTech Connect

    Hallden, D.F.

    1985-09-30

    This paper discribes the effective use of fiberglass-reinforced plastic sucker rods (FRP). FRP sucker rods have proven to be an economical solution to many sucker rod beam pumping problems. Two important characteristics that contribute to the effectiveness of FRP sucker rods are effective modulus of elasticity and fatigue life. Computerized simulations show that FRP sucker rod installations can benefit from using rod designs with a lower modulus of elasticity.

  16. Analysis of sucker rod and sinkerbar failures

    SciTech Connect

    Waggoner, J.R.; Buchheit, R.G.

    1992-12-31

    This paper presents results from a study to analyze the performance and failures of the sucker rod/sinkerbar string used in beam-pumping operations through metallography, structural finite element analysis, and detailed failure data collection. Metallography demonstrated that microstructure of steel bar stock needs to be considered. Current specification based on tensile strength, or yield strength, may not be appropriate since failure occurs because of fatigue and not yielding. Finite element analysis of the threaded connection identifies stress and fatigue concentrations and quantitatively assesses the performance and failure of coupling designs under a variety of loading conditions. Subcritical fractures observed in the metallography are also suggested by the calculated stress distribution in the threaded coupling. Failure data illustrates both magnitude and frequency of the failures, as well as categorizing the suspected cause of failure. This failure information alone can reduce failures by indicating specific problem areas. These results are expected to yield improved choice of metal bar stock, thread design, and make-up practices which can reduce sucker rod failures.

  17. Analysis of sucker rod and sinkerbar failures

    SciTech Connect

    Waggoner, J.R.; Buchheit, R.G.

    1992-01-01

    This paper presents results from a study to analyze the performance and failures of the sucker rod/sinkerbar string used in beam-pumping operations through metallography, structural finite element analysis, and detailed failure data collection. Metallography demonstrated that microstructure of steel bar stock needs to be considered. Current specification based on tensile strength, or yield strength, may not be appropriate since failure occurs because of fatigue and not yielding. Finite element analysis of the threaded connection identifies stress and fatigue concentrations and quantitatively assesses the performance and failure of coupling designs under a variety of loading conditions. Subcritical fractures observed in the metallography are also suggested by the calculated stress distribution in the threaded coupling. Failure data illustrates both magnitude and frequency of the failures, as well as categorizing the suspected cause of failure. This failure information alone can reduce failures by indicating specific problem areas. These results are expected to yield improved choice of metal bar stock, thread design, and make-up practices which can reduce sucker rod failures.

  18. Who makes API sucker rods and couplings

    SciTech Connect

    Not Available

    1986-03-01

    This guide identifies manufacturers qualified to produce API sucker rods and related equipment, lists chemical and mechanical properties of the various types of rods and provides dimensional characteristics. In addition, similar information is given for non-API rods such as fiberglass and aluminum.

  19. Device to relieve sucker rod torque below ground level in a petroleum well

    SciTech Connect

    Dysarz, E.D.

    1987-12-22

    An apparatus is described for use in a sucker rod string having a polished rod for relieving torque below the polished rod and inside of a well while the sucker rod string is moving up and down inside of the well, comprising: a body, the body that is suitably fastened to the lower end of the polished rod; at least one set of rollers that are suitably mounted within the body by axles, the rollers with a diameter greater than the width of the body; a lower swivel, and a guide. The guide is a tube that is square in section and is set vertically within the well.

  20. Sucker rod makers offer a selection

    SciTech Connect

    Savage, D.

    1983-11-01

    In their ongoing effort to produce better, more cost-effective sucker rods, manufacturers have selected one of three materials - fiberglass, aluminum, and steel - that they feel best suits the production system function of the rods, which is to connect the downhole pump to the pumpjack on the surface. Characteristics of each are described.

  1. System analysis for sucker-rod pumping

    SciTech Connect

    Schmidt, Z.; Doty, D.R.

    1989-05-01

    Pumping free gas in an oil well can significantly decrease the efficiency of a sucker-rod-pumping installation. Pump placement depth and use of a downhole gas/liquid separator (gas anchor) were found to be significant variables in improving the overall efficiency. A procedure is presented that shows when and to what degree the use of a gas anchor improves the efficiency of a sucker-rod pumping system. It was found that at lower pump intake pressures, the gas anchor usually improves efficiency, but at higher pump intake pressures, use of a gas anchor produces no positive effect. Also, elevating the pump to the highest position that still allows proper pump loading was found to reduce the operating costs of a sucker-rod-pumping installation significantly. Finally, a procedure is presented to calculate directly the pump volumetric efficiency and required volumetric pump displacement rate.

  2. System analysis for sucker rod pumping

    SciTech Connect

    Schmidt, Z.; Doty, D.R.

    1986-01-01

    Pumping free gas in an oil well can significantly decrease the efficiency of a sucker rod pumping installation. Pump placement depth and the use of a down hole gas-liquid separator (gas anchor) found to be significant variables in improving the overall efficiency. A procedure is presented which shows when and by how much the use of a gas anchor improves the efficiency of a sucker rod pumping system. It was found that at lower pump intake pressures the gas anchor usually improves efficiency, while at higher pump intake pressures the use of a gas anchor will produce no positive effect. Also, it was found at elevating the pump to the highest position which still allows for proper pump loading can significantly reduce the operating costs for a sucker rod pumping installation. Finally, a procedure is presented for directly calculating pump volumetric efficiency as well as the required volumetric pump displacement rate.

  3. Program optimizes sucker-rod pumping mode

    SciTech Connect

    Takacs, G. )

    1990-10-01

    Direct energy costs for sucker-rod pumping can be optimized by selecting the right pump size, stroke length, and pumping speed for the required liquid production rate. Calculation procedures for a computer program are developed for optimizing the design of conventional pumping units.

  4. Stop sucker rod failures to save money

    SciTech Connect

    Moore, K.H.

    1981-07-01

    This study presents examples of frequent and common sucker rod failures, explains how failures occur, presents methods to recognize these failures, and discusses changes in conditions that cause failure. From early identification, corrective measures can be taken to prevent their recurrence, reducing downtime and lost production.

  5. Method of making class D sucker rods

    SciTech Connect

    Woodings, R. T.

    1984-12-04

    It has been found that API Class D sucker rods can be made inexpensively from low-alloy, low-cost steel by following a suitable induction-normalizing process and using a suitable steel to which there has been added 0.07 to 0.15 percent of vanadium.

  6. 1984 tubing and sucker rod tables

    SciTech Connect

    Not Available

    1984-01-01

    The first section of this handy reference lists companies that produce API tubing and couplings, giving specifications for pipe in sizes from 3/4 to 41/2 in. Also listed and illustrated are special tubing joints, identified by manufacturer Additional tables provide details on API sucker rods, including manufacturers, mechanical and chemical properties, dimensions and make-up recommendations. Similar data are presented for non-API rods.

  7. Oil well sucker rod shock absorber

    SciTech Connect

    Knox, F.B.

    1986-02-18

    An oil well sucker rod shock absorber is described which consists of: an outer cylindrical casing defined by a cylindrical wall and having a removable upper plug and lower plug disposed respectively at upper and lower extremities of the casing. The upper plug has an axial bore and the lower plug defines a closed lower end and has an upwardly facing top surface. The plunger rod is connected to the sucker rod and is slidably disposed in the bore of the upper plug. A piston within the cylindrical casing is coupled to the plunger rod and has a downwardly facing bottom surface. Biasing means have a maximum vertical length disposed vertically within the casing and extending between the downwardly facing surface of the piston and the upwardly facing surface of the lower plug means at all times. This allows vertical reciprocal translation of the plunger rod and the piston within the cylindrical casing downwardly against the biasing means. Apertures are disposed through the cylindrical casing along the entire length thereof opposite the length of the biasing means, allowing downhole fluid pressure to be applied to the piston within the cylindrical casing via the apertures to be added to the force of the biasing means, without causing a fluid lock within the cylinder. Slap and wear of the sucker rod resulting therefrom are reduced and damage prevented.

  8. Tests pinpoint sucker-rod failures

    SciTech Connect

    Elshawesh, F.; Elhoud, A.; Elagdel, E.

    1997-05-26

    A detailed metallurgical examination of a 7/8-inch and a 1-inch sucker rod revealed corrosion fatigue had caused their failure. The 7 to 8-inch rod had failed after a few months of service while the 1-inch rod failed after 1 year. Both rods had been used in a sweet-oil environment. Both rods failed by corrosion fatigue because of repeated loads during operations. Pitting because of the presence of chloride ions and carbon dioxide was initiated on the rod surface, which in turn acted as a crack origin from which the fatigue crack initiated and propagated during operations. The pitting was on the external surface. These pits were large and penetrated through the rod cross-section. Fatigue cracking is initiated at the bottom of the pit where high stress concentration is expected and propagated because the rods were subjected to the alternating stresses during operation. The extent of the fatigue crack varied in the two examined rods because of the difference in the rod heat treatment and microstructure. The paper discusses fatigue failure, the visual examination, macroscopic and microscopic examinations, rod properties, and future operations.

  9. Fluid Dynamics in Sucker Rod Pumps

    SciTech Connect

    Cutler, R.P.; Mansure, A.J.

    1999-01-14

    Sucker rod pumps are installed in approximately 90% of all oil wells in the U.S. Although they have been widely used for decades, there are many issues regarding the fluid dynamics of the pump that have not been fully investigated. A project was conducted at Sandia National Laboratories to develop unimproved understanding of the fluid dynamics inside a sucker rod pump. A mathematical flow model was developed to predict pressures in any pump component or an entire pump under single-phase fluid and pumping conditions. Laboratory flow tests were conducted on instrumented individual pump components and on a complete pump to verify and refine the model. The mathematical model was then converted to a Visual Basic program to allow easy input of fluid, geometry and pump parameters and to generate output plots. Examples of issues affecting pump performance investigated with the model include the effects of viscosity, surface roughness, valve design details, plunger and valve pressure differentials, and pumping rate.

  10. Composite models for combined rod and fluid dynamics in sucker-rod pumping well systems

    SciTech Connect

    Lekia, S.D.L.

    1989-01-01

    This study presents the derivation and the numerical solution of composite models in which both the rod string and the fluid dynamics are coupled so as to accurately account for the effects of viscous friction in sucker-rod pumped wells. A viscous damped hyperbolic first order partial differential equation is coupled to the time derivative of Hooke's law to model the rod string motion and Navier Stokes equations are used to model the fluid dynamics in the rod-tubing annulus. A set of four equations comprise the composite model from which four sub-models for different flow scenarios are considered. The equations are solved numerically by a shock capturing algorithm known as the MacCormack Explicit Scheme which is a two-step predictor-corrector scheme and is second order accuracy in time and space. Five example problems covering various pump setting depths, fluid properties and surface pumping unit kinematics are presented to study the effects of certain important variables. From the analyses of the results of these example problems it is concluded that (1) while the effects of fluid dynamics may appear masked in shallow to medium depth sucker-rod pumped wells, they can not be ignored in deeper wells where large discrepancies occur in the prediction of system parameters, (2) the load range decreases moderately as viscosity increases and the predicted polished rod horsepower does not change significantly over the range of viscosities studied in shallow to medium depth sucker-rod pumped wells, (3) the presence of small quantities of the gas phase in the fluid column reduces system peak torque and precipitate the need for smaller counterbalance weights and (4) the influence of two-phase gas-liquid flow in the rod-tubing annulus on system design parameters declines with increasing pump setting depth. The results are compared against other design models appearing in the literature.

  11. Gas Interference in Sucker Rod Pump

    NASA Astrophysics Data System (ADS)

    Samad, Abdus

    2010-10-01

    Commonly used artificial lift or dewatering system is sucker rod pump and gas interference of the pump is the biggest issue in the oil and gas industry. Gas lock or fluid pound problems occur due to the gas interference when the pump has partially or completely unfilled plunger barrel. There are several techniques available in the form of patents to solve these problems but those techniques have positive as well as negative aspects. Some of the designs rely on the leakage and some of the designs rely on the mechanical arrangements etc to break the gas lock. The present article compares the existing gas interference handling techniques.

  12. Fluid Dynamics in Sucker Rod Pumps

    SciTech Connect

    Cutler, Robert P.; Mansure, Arthur J.

    1999-06-01

    Sucker rod pumps are installed in approximately 90% of all oil wells in the U.S. Although they have been widely used for decades, there are many issues regarding the fluid dynamics of the pump that have not been filly investigated. A project was conducted at Sandia National Laboratories to develop an improved understanding of the fluid dynamics inside a sucker rod pump. A mathematical flow model was developed to predict pressures in any pump component or an entire pump under single-phase fluid and pumping conditions. Laboratory flow tests were conducted on instrumented individual pump components and on a complete pump to verifi and refine the model. The mathematical model was then converted to a Visual Basic program to allow easy input of fluid, geometry and pump parameters and to generate output plots. Examples of issues affecting pump performance investigated with the model include the effects of viscosity, surface roughness, valve design details, plunger and valve pressure differentials, and pumping rate.

  13. End fitting for oil well sucker rods

    SciTech Connect

    Fischer, C.P.

    1984-02-07

    An end fitting for a sucker rod for oil wells is described with the end fitting having a chamber portion extending inwardly from one end thereof and an externally threaded portion at its other end. The chamber portion is defined by a plurality of spaced-apart annular ridges which define frusto-conical shaped cavities therebetween. The end fitting also has a bore extending inwardly thereinto from its other end which communicates with the inner end of the chamber portion. A valve is mounted in the end fitting and has a valve stem positioned in the bore and a valve head positioned at the inner end of the chamber portion. The chamber portion is adapted to receive a glass reinforced resin bonded cylindrical rod which is maintained therein by a two-part epoxy resin which surrounds the rod and is received in the cavities to form epoxy wedges bonded to the rod. The outer end of the bore is provided with internal threads which threadably receive a screw therein which engages the end of the valve stem so that longitudinal force may be applied to the valve thereby transmitting longitudinal force to the end of the rod.

  14. Guide for well pump sucker rod

    SciTech Connect

    Wilson, J.A.; Heinonen, R.L.

    1986-12-30

    This patent describes a well pump sucker rod guide comprising: a substantially cylindrical elastic body having a longitudinal bore along an axis conincident with the longitudinal axis of the body; the body having a transverse mounting slot extending from a side of the body into the body intersecting the bore and dividing the body into opposite end portions; the body having two longitudinal mounting slots; each of the end portions of the body having one of the longitudinal mounting slots opening through a side of the body into the longitudinal bore and opening at one end into the transverse mounting slot and at the other end thereof through the adjacent end of the body; the longitudinal mounting slots being aligned radially in the same directions as the transverse slot; one of the longitudinal mounting slots opening through one side of the body and the other of the longitudinal mounting slots opening through the opposite side of the body; each of the mounting slots being defined by side guide surface walls sloping radially in converging relation toward the longitudinal bore and sloping longitudinally in converging relation away from the transverse mounting slot and toward the end of the body through which each of the respective longitudinal mounting slots open.

  15. Wear resistant rod guide

    SciTech Connect

    Gray, K.W.

    1991-12-03

    This paper describes a sucker rod guide. It comprises: a series of sucker rods connected end to end forming a sucker rod string, the sucker rod string extending down into a tubing string of a producing oil well from a pump jack located on the surface of the ground above the tubing string to a pump located at a bottom end of the tubing string, the pump forces produced fluid collected at the bottom end of the tubing string up to the ground's surface, the produced fluid occupies a space between the rod string and the tubing string through which the fluid is channeled from the bottom end of the tubing string to the ground's surface, the pump jack raises and lowers the rod string in the fluid being pumped up the tubing string while the fluid bathes the rod string within the tubing string, wherein the improvement comprises the following structure in combination with the above.

  16. Calculator program aids sucker-rod systems design and optimization

    SciTech Connect

    Engineer, R.; Davis, C.; Knight, R.

    1983-08-01

    Given a few basic well parameters, the engineer may follow the step-by-step procedure for programming the design of sucker rod pumping systems for oil wells deeper than 2,000 ft using the HP-41 CV hand calculator.

  17. Mechanical performance of fiberglass laminates for sucker rod applications

    SciTech Connect

    Gauchel, J.V.

    1985-01-01

    This paper presents the results of a program designed to evaluate the tensile, shear, and tensile/tensile fatigue performance versus temperature of typical FRP pultruded laminates used in sucker rods. The predictability of performance and its sensitivity to process conditions will also be discussed.

  18. Simulation of thermal-well sucker-rod pumping

    SciTech Connect

    Wong, A. ); Sudol, T.A. )

    1992-05-01

    A major problem experienced in pumping thermal wells is low volumetric efficiencies resulting from steam and noncondensable gas interference. This paper examines the results of physical simulations performed on a full-scale sucker-rod pump test facility and numerical simulations that used an equation of state (EOS) to predict theoretical volumetric pump efficiencies.

  19. Stuffing box for a sucker rod pump assembly

    SciTech Connect

    Johnson, M.B.

    1987-03-03

    A stuffing box is described for use with a sucker rod pump assembly for a producing well including a polish rod at the upper end of the sucker rods, comprising a tubular housing for mounting on the wellhead of a producing well through which the polish rod reciprocates. Two longitudinally spaced packing assemblies are located in the tubular housing in sealing engagement with the polish rod and the housing to provide an annular chamber for a lubricating fluid to surround the polish rod. The box also comprises a lubricating fluid reservoir mounted on the tubular housing and surrounding the portion of the housing in which the annular chamber is located, upper and lower ports in the housing adjacent the upper and lower ends of the chamber connecting the annular chamber with the lubricating fluid reservoir, the housing being imperforate between the ports, and a removable annular spacer located in the annular chamber between the packing assemblies to hold the packing assemblies spaced apart. The spacer has upper and lower ports adjacent the upper and lower end of the chamber and is in substantially the same plane as the upper and lower ports in the housing.

  20. Shell runs 14,500-ft sucker rod completion

    SciTech Connect

    Wilson, J.W.

    1982-12-01

    Discusses a well in Wyoming's Reno field which features a modified downhole pump, a custom-made polished rod, and a special electric motor. String design was augmented by Shell's RodCal computer program that calculates load, stress, torque, horsepower requirements, stroke length, strokes per minute, and rod length and number. The pump is a 1 1/4-in. RHBM (API Spec. 11AX-B12) with an 11/16-in. valve rod. The polished rod is 30-ft long with a 1 1/2 diam, with a shoulder at the bottom and a conventional end at the top. The steel tapered rod string is a binary construction, run in 25-ft sections. The length of the string presented problems on the surface. To avoid midstring shock loading, Shell used an ultrahigh slip motor which slows from 1,170 to approximately 800 rpm on the downstroke to allow the string time to synchronize before starting the upstroke. The 70 b/d rate is expected to increase as the Reno field is under waterflood.

  1. Radial pressure sensor of sucker rod based on LabVIEW

    NASA Astrophysics Data System (ADS)

    Wang, Zhongyu; Yan, Hu; Li, Qiang

    2013-10-01

    The eccentric wear, fracture and other phenomena often occur to the sucker rod in major oil fields. It turns out that the radial pressure of sucker rod suffered is the main reason for its eccentric wear. It is necessary to analyze the eccentric wear and fracture of sucker rod in the pumping process. It is also important to measure the radial pressure for the downhole sucker rod accurately. The radial pressure could be analyzed when sucker rod is extruded, collided or sustained friction based on the material mechanics and the fluid dynamics. The mechanical structure is designed for measuring the radial pressure. The data processing system for radial pressure of down-hole sucker rod based on LabVIEW is developed in this paper. The functions are real-time data acquisition and processing for sucker rod radial pressure. The communication of LabVIEW and Access database had been realized. The database management system for radial pressure of sucker rod is built, which could be used to achieve the data storage, historical data retrieval analysis, data organization and calculation. The computer simulation is carried out to verify the reasonability of the theoretical analysis and structure design.

  2. NodalB{copyright}: A unique program for optimum production of sucker rod pumping oil wells

    SciTech Connect

    Guirados, C.D.; Ercolino, J.M.; Sandoval, J.L.

    1995-12-31

    Sucker rod pumping is the oldest artificial lift method used in production of oil wells. This method is usually designed and analyzed with the assistance of programs based on simplified models, such as the API RP 11L, or with a wave equation simulator. In many cases, however, a technique that permits consideration of the inflow and outflow performance of the well is a more efficient way to design and analyze an oil well. This technique, referred to as Total Analysis or System Analysis (SA), has been successfully applied to flowing and artificially lifted wells. This paper presents a computer program developed by Intevep S.A., called NodalB{copyright}, created to perform the SA of sucker rod pumping wells. NodalB{copyright}`s unique characteristics make it a competitive program in today`s market of design and optimization software. This program allows consideration of the inflow performance of the reservoir depending on the drilling scheme, either vertical or horizontal, and determination of the sensitivity of the rod pumping system to its most relevant parameters, such as: pumping speed and stroke, pump diameter, gas oil ratio, gas separation efficiency, tubing diameter, pump depth, rod string design, oil viscosity, injected diluent (diesel, kerosene, etc.) ratio, water cut, reservoir pressure, productivity index, and different production schemes (i.e. production through the tubing or through the casing-tubing annulus). These features show the power of this program as a predictive tool. NodalB{copyright} is specially applicable to design, optimization and troubleshooting of heavy and viscous oil wells, taking into account the viscosity effects in the rod pumping system.

  3. An approach to the optimum design of sucker-rod pumping systems

    SciTech Connect

    Han, D.; Wiggins, M.L.; Menzie, D.E.

    1995-12-31

    Sucker-rod pumping system design is often a trial and error process. Many simplifying assumptions are used which may not be consistent with the well conditions. This paper presents a new methodology for the optimum design of pumping unit systems. In this approach, plunger diameter, polished rod stroke length, pumping speed and pump intake pressure are chosen as basic design variables. Production rate and rod string taper are determined by an iteration algorithm which systematically couples well inflow performance and vertical flow effects into the design process. Polished rod load, peak gear box torque, polished rod horse power and counterbalance effect are also determined at the end of the iteration calculation. Different design objective functions can be used to rate the pumping modes. Thus, the optimum design of pumping unit systems becomes a matter of solving for the combination of the four basic design variables which maximize or minimize an objective function within the limitations of available equipment by a mathematical programming method.

  4. Method of installing a reinforced thermosetting resin sucker rod assembly composed of pultruded arcuate sections

    SciTech Connect

    Zion, E.M.

    1984-06-05

    Pultruded reinforced thermosetting resin arcuate sections are wound respectively on spools, the spools are transported to a well site, and the arcuate sections are unwound from the spools and assembled into a sucker rod.

  5. Adapting the sucker rod pump to your well's requirements

    SciTech Connect

    Not Available

    1981-04-01

    Devices must be incorporated in sucker rod pumps to keep an insert pump or the standing valve of a tubing pump in their working positions, yet permit their retrieval. Pump holddowns or anchors may be either cup type or mechanical; normally they are located either at the tip or the bottom of the pump. Most common in wells of approx. 6000 ft and shallower is the 3-cup holddown utilizing cups approx. 30 to 40 thousandths of an inch larger than the I.D. of their seating nipple. The hydrostatic head on the cups does most of the work. Should it be necessary to pull the anchored pump, its holddown cups function like swab cups within the restricted I.D. of the seating nipple. The pump barrel becomes a plunger in the tubing. Until the holddown cups emerge from the seating nipple into the larger tubing I.D., the pulling unit must lift, not only the rods and pump, but also all the fluid in the tubing. In deep wells, the preference is for mechanical holddowns, which release in response to a predetermined pull so that no lifting of the fluid column is involved in unseating the pump.

  6. Improving the reliability of guiding mechanisms in values of sucker-rod well pumps

    SciTech Connect

    Sotnik, V.I.; Rustamov, E.M.; Stepanova, I.S.

    1984-09-01

    This article reports on research conducted at the Azerbaijan Scientific-Research and Projects Institute for Petroleum to develop new types of valve-guiding mechanisms for sucker-rod well pumps which have high resistance to hydroabrasive and corrosive/mechanical wear and the required strength for the given load conditions. A new type of ball valve with an elastic guiding mechanism was developed for NSV1-32 and NSV1-43 sucker-rod well pumps. The new type of guiding mechanism can be made by modern high-production techniques of cold stamping which considerably reduces technological expenses compared to investment casting. Comparative tests were conducted with guiding mechanisms of elastic and rigid types (cups made for standard valves and cups of similar design with thicker ribs). The results of field tests of sucker-rod well pumps with elastic guiding mechanisms showed that they have high operating strength and wear resistance.

  7. Using a microcomputer to perform design calculations for a sucker rod pumping system

    SciTech Connect

    Parcupile, J.C.; Nicol, T.H.

    1985-03-01

    Sucker rod computations are both tedious and time consuming. Each time a pumping parameter is changed, such as rod designation, pumping speed, the calculation must be repeated. Three programs to handle these calculations have been written for the Hewlett Packard HP 87 XM microcomputer. The first program is a dynamic analysis program for either an API Class I or Class III pump. The second program performs the detailed calculations in accordance with Ref. 1 and prints a form that is essentially the same as the form No. 11L-1 of Ref. 1. The third program performs the ''RP 11L calculation'' a number of rod designations printing out: total rod weight, pump displacement, peak polish rod load, minimum polish rod load, peak torque, polish rod horsepower, maximum stress, and the ratio of daily production to polish rod horsepower for each API rod number in the range of API rod numbers being considered.

  8. A coupled rod and fluid dynamic model for predicting the behavior of sucker-rod pumping systems. Part 2: Parametric study and demonstration of model capabilities

    SciTech Connect

    Lekia, S.D. ); Evans, R.D. )

    1995-02-01

    Equations for predicting the behavior of sucker-rod pumping systems including the coupled dynamic effects of rod and fluid motion and kinematics of the surface pumping unit which were presented in Part 1 of this two-part paper series. These equations are used together with complementary sucker-rod system predictive formulas for parametric studies in this paper. Example problems are used to investigate the effects of well and fluid parameters on sucker-rod design parameters and the results are compared against calculations using the API Bulletin 11L3.

  9. Finite element analysis of sucker rod couplings with guidelines for improving fatigue life

    SciTech Connect

    Hoffman, E.L.

    1997-09-01

    The response of a variety of sucker rod couplings to an applied axial load was simulated using axisymmetric finite element models. The calculations investigated three sucker rod sizes and various combinations of the slimhole, Spiralock, and Flexbar modifications to the coupling. In addition, the effect of various make-ups (assembly tightness) on the performance of coupling was investigated. An axial load was applied to the sucker rod ranging from {minus}5 ksi to 40 ksi, encompassing three load cycles identified on a modified Goodman diagram as acceptable for indefinite service life of the sucker rods. The simulations of the various coupling geometries and make-ups were evaluated with respect to how well they accomplish the two primary objectives of preloading threaded couplings: (1) to lock the threaded coupling together so that it will not loosen and eventually uncouple, and (2) to improve the fatigue resistance of the threaded connection by reducing the stress amplitude in the coupling when subjected to cyclic loading. Perhaps the most significant finding in this study was the characterization of the coupling parameters which affect two stress measures. The mean hydrostatic stress, which determines the permissible effective alternating stress, is a function of the coupling make-up. Whereas, the alternating effective stress is a function of the relative stiffnesses of the pin and box sections of the coupling and, as long as the coupling does not separate, is unaffected by the amount of circumferential displacement applied during make-up. The results of this study suggest approaches for improving the fatigue resistance of sucker rod couplings.

  10. An improved finite-difference calculation of downhole dynamometer cards for sucker-rod pumps

    SciTech Connect

    Everitt, T.A. )

    1992-02-01

    Sucker-rod pumping is the most widely used means of artificial lift. About 85% to 90% of all producing wells in the U.S. are rod-pumped. Thus, a reliable method of analyzing these pumping system is a necessity. For many years, the surface dynamometer has been used to analyze sucker-rod systems. Interpretation of actual pump conditions from surface dynamometer cards is often difficult, if not impossible. Results obtained from surface cards are strictly qualitative and are dependent on the analyzer's expertise. The ideal analysis procedure would be to measure the actual pump conditions with a downhole dynamometer. However, this situation is not economically feasible. Therefore, an accurate method of calculating downhole pump cards form measured surface cards is needed. This paper presents a method for calculating these downhole cards that uses a finite-difference representation of the wave equation. First, a brief description of previous calculation techniques is given.

  11. A study of the methods for preventing rod-wear tubing leaks in sucker-rod pumping wells

    SciTech Connect

    McCaslin, K.P. )

    1988-11-01

    Because of the high cost associated with tubing replacement, rod-wear tubing leaks are one of the most costly types of subsurface failures on sucker-rod-pumped wells. While severe hole deviation is most often blamed for rod-wear tubing leaks, case studies show that most rod-wear leaks are caused by accelerated corrosion, which is the result of the removal of a protective corrosion scale from the inside of the tubing. For this reason, the key to eliminating rod-wear tubing leaks economically is correctly identifying the problem as either mechanical wear or corrosion wear and then implementing the appropriate corrective measures. Four case histories involving a total of 90 problem wells are presented to illustrate the methods used to differentiate between corrosion wear and mechanical wear. In these fields, tubing leaks were reduced by as much as 80% by proper identification of the cause of the leaks.

  12. Deep sucker rod pumping for gas well unloading

    SciTech Connect

    Henderson, L.J.

    1984-09-01

    Exxon Company, U.S.A.'s Pyote Gas Unit 14-1 in the Block 16 (Ellenburger) field became the world's deepest rod pumped well on October 7, 1983. The rod pump was installed at 16,850 ft. in an attempt to extend the productive life of the well. The artificial lift system was designed to lift wellbore fluid that was restricting the flow of gas, thus allowing the gas to be produced up the tubing-casing annulus. Implementation of the project was possible because of the recent improvements in predictive techniques, materials available for rod pumping, and industry's experience in artificial lift.

  13. Method speeds tapered rod design for directional well

    SciTech Connect

    Hu Yongquan; Yuan Xiangzhong

    1995-10-16

    Determination of the minimum rod diameter, from statistical relationships, can decrease the time needed for designing a sucker-rod string for a directional well. A tapered rod string design for a directional well is more complex than for a vertical well. Based on the theory of a continuous beam column, the rod string design in a directional well is a trial and error method. The key to reduce the time to obtain a solution is to rapidly determine the minimum rod diameter. This can be done with a statistical relationship. The paper describes sucker rods, design method, basic analysis rod design, and minimum rod diameter.

  14. Pump-off controllers improve sucker rod lift economics

    SciTech Connect

    Amezcua, J.D.

    1982-02-01

    A controversal issue in the production of reservoir fluids is the application, field acceptance and reliability of automatic pump-off control (POC) devices on rod pumped wells. Three distinct types of pump-off controllers were selected for an extensive evaluation and results indicate that they offer an economical means of operating pumping wells and that field acceptance is attainable.

  15. A coupled rod and fluid dynamic model for predicting the behavior of sucker-rod pumping systems. Part 1: Model theory and solution methodology

    SciTech Connect

    Lekia, S.D.L. ); Evans, R.D. )

    1995-02-01

    Equations are derived from first principles for predicting the behavior of sucker-rod pumping systems including the effects of rod and fluid dynamics, and kinematics of the surface pumping unit. Equations are also developed for both incompressible and slightly compressible fluid flow scenarios. The resulting composite rod and fluid dynamic model is solved using the MacCormack Explicit Numerical Scheme. Example problems used to validate this model are presented in a companion paper.

  16. Swivel bar apparatus for use with steel and other types of sucker rods

    SciTech Connect

    Bennett, D.W.

    1986-07-01

    A sinker bar is described for use in a well bore with a plurality of sucker rods, the sinker bar comprising; an elongated body member of suitable diameter for introduction into the well bore or into tubular members lining the well bore, at least half of the body member having a substantially square cross section and each end of the body member having a substantially square cross section, and the ends of the body member having connection means for connecting the sinker bar to adjacent members in the well bore.

  17. Production optimization of sucker rod pumping wells producing viscous oil in Boscan field, Venezuela

    SciTech Connect

    Guirados, C.; Sandoval, J.; Rivas, O.; Troconis, H.

    1995-12-31

    Boscan field is located in the western coast of Maracaibo lake and is operated by Maraven S.A., affiliate of Petroleos de Venezuela S.A. It has 315 active wells, 252 of which are produced with sucker rod pumping. Other artificial lift methods currently applied in this field are hydraulic (piston) pumping (39 wells) and ESP (24 wells). This paper presents the results of the production optimization of two sucker rod pumping wells of Boscan field producing viscous oil. This optimization has been possible due to the development of a new production scheme and the application of system analysis in completion design. The new production scheme involves the utilization of a subsurface stuffing box assembly and a slotted housing, both designed and patented by Intevep S.A., affiliate of Petroleos de Venezuela S.A. The completion design method and software used in the optimization study were also developed by Intevep S.A. The new production scheme and design method proved to be effective in preventing the causes of the above mentioned problems, allowing the increase of oil production under better operating conditions.

  18. Performance analysis and field testing of a compact dual-piston, hydraulic sucker rod pumping unit

    SciTech Connect

    Evans, R.D.; Weaver, P.

    1985-03-01

    This paper presents a new compact dual acting piston hydraulic sucker rod pumping unit. Some unique advantages of the unit are presented. Stroke length and speed are readily changed by simple adjustments made to the hydraulics. Larger hydraulic piston cylinders are interchangable without having to replace the entire unit. Performance data is presented which compares the hydraulic unit against selected conventional rotary pumping units. A comparison is made between the hydraulic unit and conventional beam pumping units. Performance evaluations were made, based on numerous accoustical well sounding and dynamometer tests. Field dynagraph cards and their analysis are presented which provide a quantitative comparison of the hydraulic unit versus the beam unit. The results obtained verify that the hydraulic unit is superior to that of a conventional well pumping unit. Economic advantages and potential applications of the hydraulic unit are discussed.

  19. What`s new in artificial lift. Part 1 -- Sucker rod pumping, progressing cavity pumping, gas lift

    SciTech Connect

    Lea, J.F.; Winkler, H.W.

    1997-03-01

    Breaking the overall concept of artificially lifting producing oil and gas wells--vs. relying solely on the wells` ability to flow at desired rates--into two parts, this article discusses the three techniques of sucker rod and progressing cavity (PC) pumping, and gas lift. In the major category of sucker rod pumping, nine recently introduced new techniques include: a new standing valve cage; three types of improved stuffing boxes; a pump inlet gas separator; a computerized well monitor; improved paraffin removal techniques; tubing lining with polyethylene; and a novel way to dispose of produced water in a gas well. Three advances for PC pumping include: introduction of a metallic stator, a flowrate controller to prevent pump damage and a locking tubing collar to prevent backoff. Two gas-lift innovations describe a wireline retrievable valve for coiled tubing and applications of CO{sub 2} gas lift in West Texas.

  20. Sucker-rod pumping wells optimization using a spreadsheet database on Barrow Island, Western Australia

    SciTech Connect

    Lee, W.; Mantecon, J.C.

    1994-12-31

    This paper demonstrates how a carefully designed spreadsheet database can be used as an innovative tool by production engineers and field operators to optimize the performance of sucker rod pumping (SRP) wells. The spreadsheet will be available on SPE EXCHANGE DISKS for potential users. Apart from individual well optimization, the database was designed to: (a) identify inefficient/low profit wells; (b) rank wells according to profit generation; (c) establish priorities to maximize revenue during production system upsets; (d) spot and fix problems early before large production losses occur; (e) evaluate and plan for long term production goals. The database provides the engineers with valuable clues indicating which wells should receive attention and where the potential for improved behavior or increased production lies. In addition, the database provides more accurate records and better retention of the information for designing or redesigning artificial lift equipment. Without the database, engineering analysis is very time consuming. The database has greatly enhanced communication between field and central office staff. When information is required, either in the field or in the central office, the database makes it easily available. Total revenue is also increased by communicating information on production priorities in a useful format.

  1. Rod coupling with mounted guide

    SciTech Connect

    Bair, M.L.

    1987-05-26

    This patent describes a well sucker rod string, in a well bore, the combination comprising: an axially elongated coupling section having threads at axially opposite ends thereof for coupling to and between successive sucker rods in the rod string, to transmit string loading. The section has first and second exposed surfaces adjacent an end of the section, and a third surface located between the first and second exposed surfaces; a rod guide consisting of molded plastic material extending about and bonded to the section third surface to project outwardly therefrom for engagement with the well bore during up and down stroking of the string; and one annular groove sunk in the section between the first and third surfaces, and another annular groove sunk in the section between the second and third surfaces. The depth of the one groove is less than about 15% of the radius of the section at the first surface.

  2. Mechanics performance test and feasibility analysis to replace the rigid sucker rod for 6K T300

    NASA Astrophysics Data System (ADS)

    Tong, Changhong

    2015-07-01

    A experiment plan was designed according to the working conditions of sucker rod and the requirements for pump depth in 3000 m in the oil field, the tensile strength for 6K T300 under a normal temperature and high temperature was measured by using universal testing machine, and then, the resistance to corrosion for a crude oil was verified by measuring the tensile strength for 6K T300 after crude oil immersion at a certain time, and the conclusions are that the material is sensitive relatively to corrosion of crude oil and that the tensile strength of the 6K T300 compared with similar products is lower, a proposal to the GH company that to meet the need of oil field production instead of the rigid rod the tensile strength and corrosion resistant for a crude of the T300 6 k materials have to do further efforts was pointed out.

  3. Drilling and production practices to mitigate sucker-rod/tubing-wear-related failures in directional wells

    SciTech Connect

    Matthews, C.M.; Dunn, L.J.

    1993-11-01

    When the Lindberg heavy-oil field in Alberta was being developed in the early 1980's, frequent wear-related workovers were experienced in wells directionally drilled from central pads. Four operating companies collaborated with the Center for Frontier Engineering Research (CFER) in a field study organized to investigate these failures and determine techniques to extend production equipment life. The study included monitoring of rod and tubing wear and production parameters in more than 50 directional wells. Results showed that wellbore configuration had a strong and consistent effect on the wear rates of downhole equipment in directional wells. It also was demonstrated that local curvature variations, which led to wear-related failures in several wells, could be attributed to drilling and surveying practices. This paper offers guidelines on wellbore geometry design to optimize the performance of mechanical lift systems and presents field-based results on the effectiveness of wear-reducing equipment. It also makes recommendations regarding an operational program designed to minimized wear-related failures. The development and applications of a model capable of predicting rod loads and tubing wear in directional or horizontal wells also are described.

  4. Pumping unit geometry vs. prime mover speed variation as a method of torsional reduction in a beam and sucker rod pumping system

    SciTech Connect

    Byrd, J.P.

    1983-11-01

    Theoretically, it is possible to effect a significant reduction in peak (in-balance) torque, with resulting cost savings, in a beam and sucker rod pumping system by two different methods. The first is the optimum selection of unit geometry; while the second employs a special, low inertia (or high slip) prime mover, permitting the unit's speed variation to more closely respond to the torsional load demand. Following is a discussion of a comparative study using the most advanced predictive technique, covering two field applications, which illuminates the relative effectiveness and economy of both methods on the torsional loading of beam pumping units, as well as the effect on other selected parameters.

  5. Rod guide

    SciTech Connect

    Sable, D.E.

    1988-11-29

    This patent describes a rod guide assembly for a sucker rod longitudinally reciprocably movable in a well flow conductor comprising: a pair of longitudinally spaced upper and lower stops rigidly secured to a sucker rod; and a guide body movably mounted on the rod between the stops. The stops being spaced from each other a distance slightly greater than the length of the guide body, the upper stop engaging the guide body to move the guide body downwardly with the rod after an initial short downward movement of the rod after initiation of each downward movement of the rod and the lower stop engaging the guide body to move the second guide body upwardly with the rod after initial short upward movement of the rod after initiation of each upward movement of the rod during the longitudinal reciprocatory movement of the rod in a well flow conductor.

  6. Coefficient indicates if rod pump can unload water from gas well

    SciTech Connect

    Hu Yongquan; Wu Zhijun

    1995-09-11

    A sucker rod pump can efficiently dewater gas wells if the separation coefficient is sufficiently high. To determine this separation coefficient, it is not sufficient to only know if the system meets the criteria of rod string stress, horsehead load, and crankshaft torque. This paper reviews water production and gas locking problems at the Sichuan gas field and identifies the methodologies used to optimize the pumping efficiency of the area wells.

  7. Rod pumping optimization program reduces equipment failures and operating costs

    SciTech Connect

    Allen, L.F.; Svinos, J.G.

    1984-09-01

    In 1975, an intensive program was initiated by Gulf Oil EandP Central Area to reduce rod and tubing failure rates in the fields of the northwest corner of Crane County, Texas. Chronologically the program steps were: The replacement of rod strings experiencing three failures in three months. The replacement of tubing strings experiencing two failures in three months. The use of inspected, classified and plastic coated new or used grade ''C'' rods. The use of inspected, classified and internally plastic coated used or new tubing. The exclusive use of high working stress rods. The exclusive use of specially designed fiberglass sucker rod systems with improved sinker bar design. This program reduced rod failure rates from 16% to 4% and tubing failures from 7% to 3% per month. The lighter rod design reduced lifting costs by $2 MM per year on 880 active wells. Of the 219 wells equipped with fiberglass sucker rods in the last two years, there have been no operational body breaks or tubing leaks.

  8. Investigation of the interrelationship of the production operations of oil-well sucker-rod pump sleeves

    SciTech Connect

    Kurbanov, A.K.

    1987-03-01

    The authors present a process and a method for its control for the production of oil well rod pump sleeves. The method makes use of regression equations and correlation functions as implemented in a Minsk-32 computer for an online control and inspection system and guarantees the accuracy of various machining operations such as honing and boring as well as nitridation in achieving specified tolerances and size and straightness requirements.

  9. Fiberglass rods present a new economic model to marginal well producers

    SciTech Connect

    Ghiselin, D.

    1996-08-01

    Fiberglass sucker rods are not new. They`ve been around for over a decade, and much has been done to improve upon their basic promise of high strength-to-weight ratio, corrosion resistance, and ease of handling. Likely the main, if not the only, reason they have not assumed prominence in the market is a resistance to change, particularly when a well becomes marginal. Operators feel that changing out their rod string is like betting on a tired horse. But there are several different scenarios involving fiberglass rods that make economic sense. To understand the argument for fiberglass rods, a case by case analysis is presented.

  10. Tubing rotator reduces tubing wear in rod pumped wells

    SciTech Connect

    Graham, M. ); Brown, C. )

    1994-04-04

    Tubing failures are both expensive and time-consuming. The most common failure results from rod cutting, or, erosion of the tubing ID because of continuous, reciprocating contact with the rod string. Installation of tubing rotators has decreased tubing failures in West Texas waterflood sucker-rod pumped wells. Pumping unit movement powers the rotator system, turning the tubing string at about 1 revolution/day. The rotator system has both surface and subsurface components. A reduction gear box attached to the walking beam converts the pumping unit's reciprocating strokes into rotary motion. A drive line transfers this rotary motion to a gear-driven suspension mandrel in the rotating tubing hanger. Near the bottom of the tubing string, a rotating tubing anchor/catcher allows the entire tubing string, including the tail pipe, seating nipple, and gas and mud anchor to rotate. The rotator hanger suspends the weight of the tubing string on a bearing system. One model of the hanger has a load capacity of 135,000 lb. A surface swivel allows rotation below the pumping tee so that the flow lines remain stationary. Also included in the string is a safety shear coupling to prevent over torquing the tubing.

  11. Low turbulence rod guide

    SciTech Connect

    Olinger, E.L.

    1992-05-26

    This patent describes an improved sucker rod guide for fixedly engaging around a sucker rod at a selected location along the length of the rod. It comprises a substantially cylindrical polymeric body having a longitudinal axis, a terminal end substantially continually tapered to the rod, a radially-inward surface and a radially outward surface, the radially inward surface of the body adjacent to and in tripping engagement with the rod when the rod guide is fixedly engaged around the rod; and a plurality of substantially continuous, longitudinal vanes carried by the body, a vane having a selected length and width, and longitudinally disposed along the radially outward surface of the guide body, extending radially away from the guide body and having a radially outside wear surface.

  12. Welded oil well pump rod

    SciTech Connect

    Hughes, R.F.

    1986-06-10

    A friction welded multiple component oil well sucker rod is described which consists of an elongated cylindrical rod section and apposed coupling end portions welded to opposite ends of the rod section, the coupling end portions being of a nominal maximum diameter at least 1.5 times greater than the rod section and including means for connecting the sucker rod to an adjacent rod in end to end relationship. The couplings end portions each include an axial tapered portion between the connecting means and an end face adapted to be butted to the rod section, the coupling end portions being butted against the opposed end portions of the rod section during a friction welding operation to form a radially outward projecting bulge of displaced material on the rod section and the coupling end portions, respectively. A greater cross-sectional area is formed at the transition of the rod section to the coupling end portion to reduce the unit tensile stress on the sucker rod in the vicinity of the weld, wherein the displaced material is machined to form a tapered surface between the rod section and the axial tapered portion of the coupling end portion, the tapered surface having an angle of taper with respect to the longitudinal axis of the sucker rod less than the angle of taper of the coupling end portion.

  13. Study on the anti-wear performance of Ni-base composite coating sucker joint that contains nano-diamond and nano-polytetrafluoroethylene.

    PubMed

    Wang, Wei-Zhang; Yan, Xiang-Zhen; Wang, Hai-Wen; Wang, Ming-Bo

    2009-02-01

    With the development of oilfields, the problem of eccentric wear between casing and sucker rod in rod-pumped wells operation is more and more severe. Investigations on the eccentric wear show that the abrasion of sucker rod joint is more serious than the sucker rod itself. A new method of producing the Ni-base composite coating that contains nano-diamond and nano-polytetrafluoroethylene (PTFE) on sucker joint obtained by electrodeposition is presented in this paper. The test results show that the anti-wear performance and hardness of the sucker rod improve significantly with the increase of nano-diamond. The addition of nano-PTFE particle is useful in reducing the friction factor. Field tests demonstrate that the life of the sucker rod joint is increased and the maintenance cycle of the rod-pumped well is prolonged. PMID:19441509

  14. Study on the anti-wear performance of Ni-base composite coating sucker joint that contains nano-diamond and nano-polytetrafluoroethylene.

    PubMed

    Wang, Wei-Zhang; Yan, Xiang-Zhen; Wang, Hai-Wen; Wang, Ming-Bo

    2009-02-01

    With the development of oilfields, the problem of eccentric wear between casing and sucker rod in rod-pumped wells operation is more and more severe. Investigations on the eccentric wear show that the abrasion of sucker rod joint is more serious than the sucker rod itself. A new method of producing the Ni-base composite coating that contains nano-diamond and nano-polytetrafluoroethylene (PTFE) on sucker joint obtained by electrodeposition is presented in this paper. The test results show that the anti-wear performance and hardness of the sucker rod improve significantly with the increase of nano-diamond. The addition of nano-PTFE particle is useful in reducing the friction factor. Field tests demonstrate that the life of the sucker rod joint is increased and the maintenance cycle of the rod-pumped well is prolonged.

  15. Oil well sucker rod coupling assembly

    SciTech Connect

    Klyne, A.A.

    1988-07-19

    A coupling assembly for connecting and centralizing a pair of elongate threaded-end members is described comprising: a pair of steel box couplings; a steel shaft connected to and extending between the couplings. The shaft having a tubular cylindrical sleeve of resilient abrasion-resistant non-metallic material bonded thereto and covering its surface between the couplings to form an integral unit therewith. Each such coupling having a ring of resilient abrasion-resistant non-metallic material bonded to and substantially fully covering the coupling's end face which is adjacent to the shaft; and a tubular externally fluted centralizer body mounted on the shaft and encircling the latter. The centralizer body extending radially outwardly beyond the longitudinal surfaces of the couplings. The centralizer body being formed of resilient abrasion-resistant non-metallic material.

  16. Rod guide/paraffin scraper

    SciTech Connect

    Mabry, J.F.

    1991-02-26

    This patent describes improvement in a rod guide and paraffin scraper. It comprises: a body including longitudinal ribs spaced radially and extending out from the body; having two identical halves with the body surrounding a bore to accept a sucker rod, and each of the identical halves having a locking and tightening feature using a tongue and groove concept for interfitting the halves together over the sucker rod. This improvement comprises a rod guide and paraffin scraper with two identical halves comprising; a cylindrical central body including, at each end, three longitudinal ribs radially spaced to form a triad leaving three flow channels, at each end of the body, of essentially the same size and spacing as the ribs; and an angular wedge with opposingly ramped sides at the inside end of each of the ribs for scraping and directing material into the flow channels; and a set of triangular shaped tongues that interfit with a set of triangular shaped grooves for tightening the identical halves together and over the sucker rod; and a pair of cone-shaped male locks at one end of the identical half to mate with a pair of cone-shaped female locks at the opposite end of the other identical half.

  17. Well tool

    SciTech Connect

    Sable, D.E.

    1992-06-09

    This patent describes a stabilizer rod conductible in a sucker rod string to constitute the bottom end portion of a rod sting and connect it to a reciprocable member of a well pump, the sucker rod string having sucker rods whose elongate shanks are provided.

  18. Calculator program speeds rod pump design

    SciTech Connect

    Engineer, R.; Davis, C.L.

    1984-02-01

    Matching sucker rod pump characteristics to a specific application is greatly simplified with this program, intended for use with an HP-41CV hand-held computer. The user inputs application data and the program calculates all necessary design criteria, including Mill's acceleration factor, peak and minimum polish rod loads and horsepower required. Sample calculations are provided, together with a thorough discussion of special design considerations involved in huff-and-puff applications.

  19. String test

    MedlinePlus

    Duodenal parasites test; Giardia - string test ... To have this test, you swallow a string with a weighted gelatin capsule on the end. The string is pulled out 4 hours later. Any bile , blood, or mucus attached to ...

  20. Rodding Surgery

    MedlinePlus

    ... Rods can be made of stainless steel or titanium. Regular rods do not expand. They have many ... v regular), the rod materials (stainless steel v titanium) and the age for a first rodding surgery. ...

  1. String Things.

    ERIC Educational Resources Information Center

    Mesa Public Schools, AZ.

    Designed for music educators instructing grades 4 through 8 in string instruments, this Mesa (Arizona) public schools guide presents information on the string curriculum, orchestras, and practicing. The goals and objectives for string instruments delineate grade levels and how student skills will be verified. Following 17 curriculum goal tests,…

  2. Hammered Strings

    NASA Astrophysics Data System (ADS)

    Rossing, Thomas D.

    In the next three chapters we consider the science of hammered string instruments. In this chapter, we present a brief discussion of vibrating strings excited by a hard or soft hammer. Chapter 20 discusses the most important hammered string instrument, the piano - probably the most versatile and popular of all musical instruments. Chapter 21 discusses hammered dulcimers, especially the American folk dulcimer.

  3. Field-wide program improves sucker rod pumping efficiency

    SciTech Connect

    DeFoe, P.R.

    1981-08-01

    A discussion is presented of a three year old project in which equipment is checked to assure proper design and operation is paying off with substantial savings in maintenance costs. Also, the resulting increase in downhole pump life keeps wells on stream for longer periods. 5 refs.

  4. Hand-held computer designs rod pumping installation

    SciTech Connect

    Herlihy, J.D.

    1984-10-01

    This article describes the program designed to facilitate the design of sucker rod pumping systems for conventional and Mark 2 units. For depths of 2000' or less the modified Mill's method is used, and below 2000' the design procedures of API RP llL are incorporated. The program automatically uses the appropriate design procedure depending on the fluid or pump level. The pump depth is used to calculate rod weighs and the working fluid level to calculate net lift considerations.

  5. Bowed Strings

    NASA Astrophysics Data System (ADS)

    Rossing, Thomas D.; Hanson, Roger J.

    In the next eight chapters, we consider some aspects of the science of bowed string instruments, old and new. In this chapter, we present a brief discussion of bowed strings, a subject that will be developed much more thoroughly in Chap. 16. Chapters 13-15 discuss the violin, the cello, and the double bass. Chapter 17 discusses viols and other historic string instruments, and Chap. 18 discusses the Hutchins-Schelleng violin octet.

  6. Sucker-like structures on the pathogenic amoeba Naegleria fowleri.

    PubMed

    John, D T; Cole, T B; Marciano-Cabral, F M

    1984-01-01

    Using scanning electron microscopy, we observed sucker-like structures on amoebae of 13 human isolates of Naegleria fowleri. The number of suckers per amoeba seemed to vary according to the virulence of the strain. We propose the term amoebastome to describe this unique sucker-like structure of N. fowleri.

  7. Cosmic strings

    NASA Technical Reports Server (NTRS)

    Bennett, David P.

    1988-01-01

    Cosmic strings are linear topological defects which are predicted by some grand unified theories to form during a spontaneous symmetry breaking phase transition in the early universe. They are the basis for the only theories of galaxy formation aside from quantum fluctuations from inflation based on fundamental physics. In contrast to inflation, they can also be observed directly through gravitational lensing and their characterisitc microwave background anisotropy. It was recently discovered that details of cosmic string evolution are very differnt from the so-called standard model that was assumed in most of the string-induced galaxy formation calculations. Therefore, the details of galaxy formation in the cosmic string models are currently very uncertain.

  8. Cosmic strings

    SciTech Connect

    Bennett, D.P.

    1988-07-01

    Cosmic strings are linear topological defects that are predicted by some grand unified theories to form during a spontaneous symmetry breaking phase transition in the early universe. They are the basis for the only theories of galaxy formation aside from quantum fluctuations from inflation that are based on fundamental physics. In contrast to inflation, they can also be observed directly through gravitational lensing and their characteristic microwave background anistropy. It has recently been discovered by F. Bouchet and myself that details of cosmic string evolution are very different from the so-called ''standard model'' that has been assumed in most of the string induced galaxy formation calculations. Therefore, the details of galaxy formation in the cosmic string models are currently very uncertain. 29 refs., 9 figs.

  9. Dark strings

    SciTech Connect

    Vachaspati, Tanmay

    2009-09-15

    Recent astrophysical observations have motivated novel theoretical models of the dark matter sector. A class of such models predicts the existence of GeV scale cosmic strings that communicate with the standard model sector by Aharonov-Bohm interactions with electrically charged particles. We discuss the cosmology of these 'dark strings' and investigate possible observational signatures. More elaborate dark sector models are argued to contain hybrid topological defects that may also have observational signatures.

  10. Demographic analysis of Lost River sucker and shortnose sucker populations in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Janney, E.C.; Shively, R.S.; Hayes, B.S.; Barry, P.M.; Perkins, D.

    2008-01-01

    We used 13 years (1995-2007) of capture-mark-recapture data to assess population dynamics of endangered Lost River suckers Deltistes luxatus and shortnose suckers Chasmistes brevirostris in Upper Klamath Lake, Oregon. The Cormack-Jolly-Seber method was used to estimate survival, and information theoretic modeling was used to assess variation due to time, gender, species, and spawning subpopulations. Length data were used to detect multiple year-class failures and events of high recruitment into adult spawning populations. Average annual survival probability was 0.88 for Lost River suckers and 0.76 for shortnose suckers. Mean life span estimates based on these survival rates indicated that Lost River suckers survived long enough on average to attempt reproduction eight times, whereas shortnose suckers only survived to spawn three to four times. Shortnose sucker survival was not only poor in years of fish kills (1995-1997) but also was low in years without fish kills (i.e., 2002 and 2004). This suggests that high mortality occurs in some years but is not necessarily associated with fish kills. Annual survival probabilities were not only different between the two species but also differed between two spawning subpopulations of Lost River suckers. Length composition data indicated that recruitment into spawning populations only occurred intermittently. Populations of both species transitioned from primarily old individuals with little size diversity and consistently poor recruitment in the late 1980s and early 1990s to mostly small, recruit-sized fish by the late 1990s. A better understanding of the factors influencing adult survival and recruitment into spawning populations is needed. Monitoring these vital parameters will provide a quantitative means to evaluate population status and assess the effectiveness of conservation and recovery efforts.

  11. Cosmic strings and superconducting cosmic strings

    NASA Technical Reports Server (NTRS)

    Copeland, Edmund

    1988-01-01

    The possible consequences of forming cosmic strings and superconducting cosmic strings in the early universe are discussed. Lecture 1 describes the group theoretic reasons for and the field theoretic reasons why cosmic strings can form in spontaneously broken gauge theories. Lecture 2 discusses the accretion of matter onto string loops, emphasizing the scenario with a cold dark matter dominated universe. In lecture 3 superconducting cosmic strings are discussed, as is a mechanism which leads to the formation of structure from such strings.

  12. Plucked Strings

    NASA Astrophysics Data System (ADS)

    Rossing, Thomas D.

    In the next ten chapters we will discuss the science of plucked string instruments. Acoustic guitars and lutes are discussed in Chap. 3. Portuguese guitars, used in fado music, are discussed in Chap. 4 and guitars in Chap. 5, while electric guitars are discussed in Chap. 22. Banjos are discussed in Chap. 5, while mandolins are the subject of Chap. 6. Zithers and psalteries, especially Baltic psalteries, are discussed in Chap. 7. Harpsichords are discussed in Chap. 8, while harps are discussed in Chap. 9 and 10. Finally, plucked string instruments from Asia, such as the kito, shamisen, biwa, gayageum, geomungo, ch'in, p'I-p'a, and sitar are discussed in Chap. 11. These instruments are very different in character and in their musical roles, but they all depend upon plucked strings vibrating and exciting one or more soundboards or radiating surfaces.

  13. A rod pumping system to reduce lifting costs

    SciTech Connect

    Tait, H.C.; Hamilton, R.M.

    1983-02-01

    Rising costs of artificial lift operations are a growing concern to producers in maintaining efficient and profitable performance. A new long stroke sucker rod pumping system has been developed to minimize the impact of these rising costs. This new system results from a broad development project involving evaluation of all system components. Performance results to date confirm achievement of reduced overall operating costs as a result of the performance characteristics of this system.

  14. Teaching Strings.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.

    Intended primarily for use by instrumental music teachers who do not have a major concentration in strings, this guide provides pertinent basic resources, materials, teaching--learning expectation, and a general overall guide to achievement levels at various stages of development. Discussions are presented of Choosing the Proper Method Book,…

  15. The "Magic" String

    ERIC Educational Resources Information Center

    Hoover, Todd F.

    2010-01-01

    The "Magic" String is a discrepant event that includes a canister with what appears to be the end of two strings protruding from opposite sides of it. Due to the way the strings are attached inside the canister, it appears as if the strings can magically switch the way they are connected. When one string end is pulled, the observer's expectation…

  16. String mediated phase transitions

    NASA Technical Reports Server (NTRS)

    Copeland, ED; Haws, D.; Rivers, R.; Holbraad, S.

    1988-01-01

    It is demonstrated from first principles how the existence of string-like structures can cause a system to undergo a phase transition. In particular, the role of topologically stable cosmic string in the restoration of spontaneously broken symmetries is emphasized. How the thermodynamic properties of strings alter when stiffness and nearest neighbor string-string interactions are included is discussed.

  17. Ribbon rod for use in oil well apparatus

    SciTech Connect

    Tanner, C.J.; Bender, R.E.; Simson, A.K.; McCutchen, H. Jr.

    1986-01-07

    This patent describes a ribbon rod for use in oil well tubing as a replacement for a conventional steel sucker rod. The ribbon rod consists of: an elongated ribbon having a core of relatively stiff material that still has a degree of flexibility such that the ribbon is capable of being wound onto and dispensed from a rotatable reel and can support the weight of oil pumping apparatus attached to a downhole portion of the ribbon, the ribbon core having opposed side surfaces and relatively narrow end surfaces joining the side surfaces; a ply of fabric overlying the side surfaces to provide transverse strength to the ribbon rod; and corner tows extending over the end surfaces to provide damage resistance to the ribbon as it is raised and lowered in the oil well tubing.

  18. 21 CFR 870.4420 - Cardiopulmonary bypass cardiotomy return sucker.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass cardiotomy return sucker... Cardiopulmonary bypass cardiotomy return sucker. (a) Identification. A cardiopulmonary bypass cardiotomy return... from the chest or heart during cardiopulmonary bypass surgery. (b) Classification. Class...

  19. Juvenile sucker cohort tracking data summary and assessment of monitoring program, 2015

    USGS Publications Warehouse

    Burdick, Summer M.; Ostberg, Carl O.; Hereford, Mark E.; Hoy, Marshal S.

    2016-09-22

    Condition of suckers was assessed in 2015 based on age-0 sucker growth rates in Upper Klamath Lake and the prevalence of externally observable afflictions on suckers from both lakes. Age-0 Lost River suckers grew an average (± standard deviation [SD]) of 0.72 (±

  20. Experience reveals ways to minimize failures in rod-pumped wells

    SciTech Connect

    Patterson, J.C.; Bucaram, S.M. ); Curfew, J.V. )

    1993-07-05

    From the experience gained over the past 25 years, ARCO Oil and Gas Co. has developed recommendations to reduce equipment failure in sucker-rod pumping installations. These recommendations include equipment selection and design, operating procedures, and chemical treatment. Equipment failure and its attendant costs are extremely important in today's petroleum industry. Because rod pumping is the predominant means of artificial lift, minimizing equipment failure in rod pumped wells can have a significant impact on profitability. This compilation of recommendations comes from field locations throughout the US and other countries. The goal is to address and solve problems on a well-by-well basis.

  1. CONTROL ROD

    DOEpatents

    Zinn, W.H.; Ross, H.V.

    1958-11-18

    A control rod is described for a nuclear reactor. In certaln reactor designs it becomes desirable to use a control rod having great width but relatively llttle thickness. This patent is addressed to such a need. The neutron absorbing material is inserted in a triangular tube, leaving volds between the circular insert and the corners of the triangular tube. The material is positioned within the tube by the use of dummy spacers to achleve the desired absorption pattern, then the ends of the tubes are sealed with suitable plugs. The tubes may be welded or soldered together to form two flat surfaces of any desired width, and covered with sheetmetal to protect the tubes from damage. This design provides a control member that will not distort under the action of outside forces or be ruptured by gases generated within the jacketed control member.

  2. Constraint Reasoning Over Strings

    NASA Technical Reports Server (NTRS)

    Koga, Dennis (Technical Monitor); Golden, Keith; Pang, Wanlin

    2003-01-01

    This paper discusses an approach to representing and reasoning about constraints over strings. We discuss how many string domains can often be concisely represented using regular languages, and how constraints over strings, and domain operations on sets of strings, can be carried out using this representation.

  3. Evidence for string substructure

    SciTech Connect

    Bergman, O.

    1996-06-01

    The author argues that the behavior of string theory at high temperature and high longitudinal boosts, combined with the emergence of p-branes as necessary ingredients in various string dualities, point to a possible reformulation of strings, as well as p-branes, as composites of bits. He reviews the string-bit models, and suggests generalizations to incorporate p-branes.

  4. String driven inflation

    SciTech Connect

    Turok, N.

    1987-11-01

    It is argued that, in fundamental string theories, as one traces the universe back in time a point is reached when the expansion rate is so fast that the rate of string creation due to quantum effects balances the dilution of the string density due to the expansion. One is therefore led into a phase of constant string density and an exponentially expanding universe. Fundamental strings therefore seem to lead naturally to inflation. 17 refs., 1 fig.

  5. String-driven inflation

    NASA Technical Reports Server (NTRS)

    Turok, Neil

    1988-01-01

    It is argued that, in fundamental string theories, as one traces the universe back in time a point is reached when the expansion rate is so fast that the rate of string creation due to quantum effects balances the dilution of the string density due to the expansion. One is therefore led into a phase of constant string density and an exponentially expanding universe. Fundamental strings therefore seem to lead naturally to inflation.

  6. String axiverse

    SciTech Connect

    Arvanitaki, Asimina; Dimopoulos, Savas; Dubovsky, Sergei; Kaloper, Nemanja; March-Russell, John

    2010-06-15

    String theory suggests the simultaneous presence of many ultralight axions, possibly populating each decade of mass down to the Hubble scale 10{sup -33} eV. Conversely the presence of such a plenitude of axions (an axiverse) would be evidence for string theory, since it arises due to the topological complexity of the extra-dimensional manifold and is ad hoc in a theory with just the four familiar dimensions. We investigate how several upcoming astrophysical experiments will be observationally exploring the possible existence of such axions over a vast mass range from 10{sup -33} eV to 10{sup -10} eV. Axions with masses between 10{sup -33} eV to 10{sup -28} eV can cause a rotation of the cosmic microwave background polarization that is constant throughout the sky. The predicted rotation angle is independent of the scale of inflation and the axion decay constant, and is of order {alpha}{approx}1/137-within reach of the just launched Planck satellite. Axions in the mass range 10{sup -28} eV to 10{sup -18} eV give rise to multiple steps in the matter power spectrum, providing us with a snapshot of the axiverse that will be probed by galaxy surveys-such as BOSS, and 21 cm line tomography. Axions in the mass range 10{sup -22} eV to 10{sup -10} eV can affect the dynamics and gravitational wave emission of rapidly rotating astrophysical black holes through the Penrose superradiance process. When the axion Compton wavelength is of order of the black hole size, the axions develop superradiant atomic bound states around the black hole nucleus. Their occupation number grows exponentially by extracting rotational energy and angular momentum from the ergosphere, culminating in a rotating Bose-Einstein axion condensate emitting gravitational waves. For black holes lighter than {approx}10{sup 7} solar masses accretion cannot replenish the spin of the black hole, creating mass gaps in the spectrum of rapidly rotating black holes that diagnose the presence of destabilizing axions

  7. Structure and mechanical properties of Octopus vulgaris suckers.

    PubMed

    Tramacere, Francesca; Kovalev, Alexander; Kleinteich, Thomas; Gorb, Stanislav N; Mazzolai, Barbara

    2014-02-01

    In this study, we investigate the morphology and mechanical features of Octopus vulgaris suckers, which may serve as a model for the creation of a new generation of attachment devices. Octopus suckers attach to a wide range of substrates in wet conditions, including rough surfaces. This amazing feature is made possible by the sucker's tissues, which are pliable to the substrate profile. Previous studies have described a peculiar internal structure that plays a fundamental role in the attachment and detachment processes of the sucker. In this work, we present a mechanical characterization of the tissues involved in the attachment process, which was performed using microindentation tests. We evaluated the elasticity modulus and viscoelastic parameters of the natural tissues (E ∼ 10 kPa) and measured the mechanical properties of some artificial materials that have previously been used in soft robotics. Such a comparison of biological prototypes and artificial material that mimics octopus-sucker tissue is crucial for the design of innovative artificial suction cups for use in wet environments. We conclude that the properties of the common elastomers that are generally used in soft robotics are quite dissimilar to the properties of biological suckers. PMID:24284894

  8. Structure and mechanical properties of Octopus vulgaris suckers

    PubMed Central

    Tramacere, Francesca; Kovalev, Alexander; Kleinteich, Thomas; Gorb, Stanislav N.; Mazzolai, Barbara

    2014-01-01

    In this study, we investigate the morphology and mechanical features of Octopus vulgaris suckers, which may serve as a model for the creation of a new generation of attachment devices. Octopus suckers attach to a wide range of substrates in wet conditions, including rough surfaces. This amazing feature is made possible by the sucker's tissues, which are pliable to the substrate profile. Previous studies have described a peculiar internal structure that plays a fundamental role in the attachment and detachment processes of the sucker. In this work, we present a mechanical characterization of the tissues involved in the attachment process, which was performed using microindentation tests. We evaluated the elasticity modulus and viscoelastic parameters of the natural tissues (E ∼ 10 kPa) and measured the mechanical properties of some artificial materials that have previously been used in soft robotics. Such a comparison of biological prototypes and artificial material that mimics octopus-sucker tissue is crucial for the design of innovative artificial suction cups for use in wet environments. We conclude that the properties of the common elastomers that are generally used in soft robotics are quite dissimilar to the properties of biological suckers. PMID:24284894

  9. Structure and mechanical properties of Octopus vulgaris suckers.

    PubMed

    Tramacere, Francesca; Kovalev, Alexander; Kleinteich, Thomas; Gorb, Stanislav N; Mazzolai, Barbara

    2014-02-01

    In this study, we investigate the morphology and mechanical features of Octopus vulgaris suckers, which may serve as a model for the creation of a new generation of attachment devices. Octopus suckers attach to a wide range of substrates in wet conditions, including rough surfaces. This amazing feature is made possible by the sucker's tissues, which are pliable to the substrate profile. Previous studies have described a peculiar internal structure that plays a fundamental role in the attachment and detachment processes of the sucker. In this work, we present a mechanical characterization of the tissues involved in the attachment process, which was performed using microindentation tests. We evaluated the elasticity modulus and viscoelastic parameters of the natural tissues (E ∼ 10 kPa) and measured the mechanical properties of some artificial materials that have previously been used in soft robotics. Such a comparison of biological prototypes and artificial material that mimics octopus-sucker tissue is crucial for the design of innovative artificial suction cups for use in wet environments. We conclude that the properties of the common elastomers that are generally used in soft robotics are quite dissimilar to the properties of biological suckers.

  10. A rod pumping system to reduce lifting costs

    SciTech Connect

    Tait, H.C.; Hamilton, R.M.

    1984-11-01

    Rising costs of artificial lift operations are a continuing concern to oil producers in maintaining efficient and profitable performance. A new long-stroke sucker rod pumping system has been developed to minimize the impact of these rising costs. This new system results from a broad development project based on system design considerations having major influence on overall cost effectiveness of the system. The basis of these evaluations is discussed, resulting equipment design is described, and field operating results are presented. Performance results to date confirm achievement of reduced overall operating costs as a result of the performance characteristics of this system.

  11. String resistance detector

    NASA Technical Reports Server (NTRS)

    Hall, A. Daniel (Inventor); Davies, Francis J. (Inventor)

    2007-01-01

    Method and system are disclosed for determining individual string resistance in a network of strings when the current through a parallel connected string is unknown and when the voltage across a series connected string is unknown. The method/system of the invention involves connecting one or more frequency-varying impedance components with known electrical characteristics to each string and applying a frequency-varying input signal to the network of strings. The frequency-varying impedance components may be one or more capacitors, inductors, or both, and are selected so that each string is uniquely identifiable in the output signal resulting from the frequency-varying input signal. Numerical methods, such as non-linear regression, may then be used to resolve the resistance associated with each string.

  12. Sorting Symbol Strings

    ERIC Educational Resources Information Center

    Novak, Jodie D.; Jacobs, Judith E.

    2005-01-01

    This article describes a variety of activities that ask students to identify, describe, compare, and classify symbol strings (algebraic expressions and equations). The activities use a collection of twelve symbol strings on cards. (Contains 2 figures.)

  13. Light from cosmic strings

    SciTech Connect

    Steer, Daniele A.; Vachaspati, Tanmay

    2011-02-15

    The time-dependent metric of a cosmic string leads to an effective interaction between the string and photons--the ''gravitational Aharonov-Bohm'' effect--and causes cosmic strings to emit light. We evaluate the radiation of pairs of photons from cosmic strings and find that the emission from cusps, kinks and kink-kink collisions occurs with a flat spectrum at all frequencies up to the string scale. Further, cusps emit a beam of photons, kinks emit along a curve, and the emission at a kink-kink collision is in all directions. The emission of light from cosmic strings could provide an important new observational signature of cosmic strings that is within reach of current experiments for a range of string tensions.

  14. Age-0 Lost River sucker and shortnose sucker nearshore habitat use in Upper Klamath Lake, Oregon: A patch occupancy approach

    USGS Publications Warehouse

    Burdick, S.M.; Hendrixson, H.A.; VanderKooi, S.P.

    2008-01-01

    We examined habitat use by age-0 Lost River suckers Deltistes luxatus and shortnose suckers Chasmistes brevirostris over six substrate classes and in vegetated and nonvegetated areas of Upper Klamath Lake, Oregon. We used a patch occupancy approach to model the effect of physical habitat and water quality conditions on habitat use. Our models accounted for potential inconsistencies in detection probability among sites and sampling occasions as a result of differences in fishing gear types and techniques, habitat characteristics, and age-0 fish size and abundance. Detection probability was greatest during mid- to late summer, when water temperatures were highest and age-0 suckers were the largest. The proportion of sites used by age-0 suckers was inversely related to depth (range = 0.4-3.0 m), particularly during late summer. Age-0 suckers were more likely to use habitats containing small substrate (64 mm) and habitats with vegetation than those without vegetation. Relatively narrow ranges in dissolved oxygen, temperature, and pH prevented us from detecting effects of these water quality features on age-0 sucker nearshore habitat use.

  15. [The string of Einthoven's string galvanometer].

    PubMed

    Wyers, P J

    1996-01-01

    The Dutch physiologist Willem Einthoven (1860-1927) published in 1901 his construction of a string galvanometer. With this apparatus he opened the era for electrocardiography. As the quality of his instrument largely depended on the string of the string galvanometer it is surprising to note that in his publications Einthoven never mentioned the exact way of producing the string. However, Einthoven's hand written laboratory notes are preserved at the Museum Boerhaave in Leiden. From these notes it comes clear what problems Einthoven had with the string. To get a very thin thread of quarts he first used the method of shooting the thread as was described by Boys (1887), later the blowing method of Nichols (1894). The silvering of the thread was done first chemically, later by cathode spray. In all cases premature breaking of the thread was a nuisance. Because of these failures Einthoven might have decided not to publish any details.

  16. [The string of Einthoven's string galvanometer].

    PubMed

    Wyers, P J

    1996-01-01

    The Dutch physiologist Willem Einthoven (1860-1927) published in 1901 his construction of a string galvanometer. With this apparatus he opened the era for electrocardiography. As the quality of his instrument largely depended on the string of the string galvanometer it is surprising to note that in his publications Einthoven never mentioned the exact way of producing the string. However, Einthoven's hand written laboratory notes are preserved at the Museum Boerhaave in Leiden. From these notes it comes clear what problems Einthoven had with the string. To get a very thin thread of quarts he first used the method of shooting the thread as was described by Boys (1887), later the blowing method of Nichols (1894). The silvering of the thread was done first chemically, later by cathode spray. In all cases premature breaking of the thread was a nuisance. Because of these failures Einthoven might have decided not to publish any details. PMID:11624925

  17. Drill string enclosure

    DOEpatents

    Jorgensen, Douglas K.; Kuhns, Douglass J.; Wiersholm, Otto; Miller, Timothy A.

    1993-01-01

    The drill string enclosure consists of six component parts, including; a top bracket, an upper acrylic cylinder, an acrylic drill casing guide, a lower acrylic cylinder, a bottom bracket, and three flexible ducts. The upper acrylic cylinder is optional based upon the drill string length. The drill string enclosure allows for an efficient drill and sight operation at a hazardous waste site.

  18. Drill string enclosure

    DOEpatents

    Jorgensen, D.K.; Kuhns, D.J.; Wiersholm, O.; Miller, T.A.

    1993-03-02

    The drill string enclosure consists of six component parts, including; a top bracket, an upper acrylic cylinder, an acrylic drill casing guide, a lower acrylic cylinder, a bottom bracket, and three flexible ducts. The upper acrylic cylinder is optional based upon the drill string length. The drill string enclosure allows for an efficient drill and sight operation at a hazardous waste site.

  19. Heavy cosmic strings

    SciTech Connect

    Donaire, M.; Rajantie, A.

    2006-03-15

    We argue that cosmic strings with high winding numbers generally form in first-order gauge symmetry breaking phase transitions, and we demonstrate this using computer simulations. These strings are heavier than single-winding strings and therefore more easily observable. Their cosmological evolution may also be very different.

  20. Dynamics of Carroll strings

    NASA Astrophysics Data System (ADS)

    Cardona, Biel; Gomis, Joaquim; Pons, Josep M.

    2016-07-01

    We construct the canonical action of a Carroll string doing the Carroll limit of a canonical relativistic string. We also study the Killing symmetries of the Carroll string, which close under an infinite dimensional algebra. The tensionless limit and the Carroll p-brane action are also discussed.

  1. The morphology and adhesion mechanism of Octopus vulgaris suckers.

    PubMed

    Tramacere, Francesca; Beccai, Lucia; Kuba, Michael; Gozzi, Alessandro; Bifone, Angelo; Mazzolai, Barbara

    2013-01-01

    The octopus sucker represents a fascinating natural system performing adhesion on different terrains and substrates. Octopuses use suckers to anchor the body to the substrate or to grasp, investigate and manipulate objects, just to mention a few of their functions. Our study focuses on the morphology and adhesion mechanism of suckers in Octopus vulgaris. We use three different techniques (MRI, ultrasonography, and histology) and a 3D reconstruction approach to contribute knowledge on both morphology and functionality of the sucker structure in O. vulgaris. The results of our investigation are two-fold. First, we observe some morphological differences with respect to the octopus species previously studied (i.e., Octopus joubini, Octopus maya, Octopus bimaculoides/bimaculatus and Eledone cirrosa). In particular, in O. vulgaris the acetabular chamber, that is a hollow spherical cavity in other octopuses, shows an ellipsoidal cavity which roof has an important protuberance with surface roughness. Second, based on our findings, we propose a hypothesis on the sucker adhesion mechanism in O. vulgaris. We hypothesize that the process of continuous adhesion is achieved by sealing the orifice between acetabulum and infundibulum portions via the acetabular protuberance. We suggest this to take place while the infundibular part achieves a completely flat shape; and, by sustaining adhesion through preservation of sucker configuration. In vivo ultrasonographic recordings support our proposed adhesion model by showing the sucker in action. Such an underlying physical mechanism offers innovative potential cues for developing bioinspired artificial adhesion systems. Furthermore, we think that it could possibly represent a useful approach in order to investigate any potential difference in the ecology and in the performance of adhesion by different species.

  2. The morphology and adhesion mechanism of Octopus vulgaris suckers.

    PubMed

    Tramacere, Francesca; Beccai, Lucia; Kuba, Michael; Gozzi, Alessandro; Bifone, Angelo; Mazzolai, Barbara

    2013-01-01

    The octopus sucker represents a fascinating natural system performing adhesion on different terrains and substrates. Octopuses use suckers to anchor the body to the substrate or to grasp, investigate and manipulate objects, just to mention a few of their functions. Our study focuses on the morphology and adhesion mechanism of suckers in Octopus vulgaris. We use three different techniques (MRI, ultrasonography, and histology) and a 3D reconstruction approach to contribute knowledge on both morphology and functionality of the sucker structure in O. vulgaris. The results of our investigation are two-fold. First, we observe some morphological differences with respect to the octopus species previously studied (i.e., Octopus joubini, Octopus maya, Octopus bimaculoides/bimaculatus and Eledone cirrosa). In particular, in O. vulgaris the acetabular chamber, that is a hollow spherical cavity in other octopuses, shows an ellipsoidal cavity which roof has an important protuberance with surface roughness. Second, based on our findings, we propose a hypothesis on the sucker adhesion mechanism in O. vulgaris. We hypothesize that the process of continuous adhesion is achieved by sealing the orifice between acetabulum and infundibulum portions via the acetabular protuberance. We suggest this to take place while the infundibular part achieves a completely flat shape; and, by sustaining adhesion through preservation of sucker configuration. In vivo ultrasonographic recordings support our proposed adhesion model by showing the sucker in action. Such an underlying physical mechanism offers innovative potential cues for developing bioinspired artificial adhesion systems. Furthermore, we think that it could possibly represent a useful approach in order to investigate any potential difference in the ecology and in the performance of adhesion by different species. PMID:23750233

  3. The Morphology and Adhesion Mechanism of Octopus vulgaris Suckers

    PubMed Central

    Tramacere, Francesca; Beccai, Lucia; Kuba, Michael; Gozzi, Alessandro; Bifone, Angelo; Mazzolai, Barbara

    2013-01-01

    The octopus sucker represents a fascinating natural system performing adhesion on different terrains and substrates. Octopuses use suckers to anchor the body to the substrate or to grasp, investigate and manipulate objects, just to mention a few of their functions. Our study focuses on the morphology and adhesion mechanism of suckers in Octopus vulgaris. We use three different techniques (MRI, ultrasonography, and histology) and a 3D reconstruction approach to contribute knowledge on both morphology and functionality of the sucker structure in O. vulgaris. The results of our investigation are two-fold. First, we observe some morphological differences with respect to the octopus species previously studied (i.e., Octopus joubini, Octopus maya, Octopus bimaculoides/bimaculatus and Eledone cirrosa). In particular, in O. vulgaris the acetabular chamber, that is a hollow spherical cavity in other octopuses, shows an ellipsoidal cavity which roof has an important protuberance with surface roughness. Second, based on our findings, we propose a hypothesis on the sucker adhesion mechanism in O. vulgaris. We hypothesize that the process of continuous adhesion is achieved by sealing the orifice between acetabulum and infundibulum portions via the acetabular protuberance. We suggest this to take place while the infundibular part achieves a completely flat shape; and, by sustaining adhesion through preservation of sucker configuration. In vivo ultrasonographic recordings support our proposed adhesion model by showing the sucker in action. Such an underlying physical mechanism offers innovative potential cues for developing bioinspired artificial adhesion systems. Furthermore, we think that it could possibly represent a useful approach in order to investigate any potential difference in the ecology and in the performance of adhesion by different species. PMID:23750233

  4. Dilatonic global strings

    NASA Astrophysics Data System (ADS)

    Dando, Owen; Gregory, Ruth

    1998-07-01

    We examine the field equations of a self-gravitating global string in low energy superstring gravity, allowing for an arbitrary coupling of the global string to the dilaton. Massive and massless dilatons are considered. For the massive dilaton the spacetime is similar to the recently discovered non-singular time-dependent Einstein self-gravitating global string, but the massless dilaton generically gives a singular spacetime, even allowing for time dependence. We also demonstrate a time-dependent non-singular string-antistring configuration, in which the string pair causes a compactification of two of the spatial dimensions, albeit on a very large scale.

  5. Semilocal cosmic string networks

    SciTech Connect

    Achucarro, Ana; Salmi, Petja; Urrestilla, Jon

    2007-06-15

    We report on a large-scale numerical study of networks of semilocal cosmic strings in flat space in the parameter regime in which they are perturbatively stable. We find a population of segments with an exponential length distribution and indications of a scaling network without significant loop formation. Very deep in the stability regime strings of superhorizon size grow rapidly and ''percolate'' through the box. We believe these should lead at late times to a population of infinite strings similar to topologically stable strings. However, the strings are very light; scalar gradients dominate the energy density, and the network has thus a global texturelike signature. As a result, the observational constraints, at least from the temperature power spectrum of the cosmic microwave background, on models predicting semilocal strings should be closer to those on global textures or monopoles, rather than on topologically stable gauged cosmic strings.

  6. Rod examination gauge

    SciTech Connect

    Bacvinskas, W.S.; Bayer, J.E.; Davis, W.W.; Fodor, G.; Kikta, T.J.; Matchett, R.L.; Nilsen, R.J.; Wilczynski, R.

    1991-12-31

    The present invention is directed to a semi-automatic rod examination gauge for performing a large number of exacting measurements on radioactive fuel rods. The rod examination gauge performs various measurements underwater with remote controlled machinery of high reliability. The rod examination gauge includes instruments and a closed circuit television camera for measuring fuel rod length, free hanging bow measurement, diameter measurement, oxide thickness measurement, cladding defect examination, rod ovality measurement, wear mark depth and volume measurement, as well as visual examination. A control system is provided including a programmable logic controller and a computer for providing a programmed sequence of operations for the rod examination and collection of data.

  7. Hazard assessment of selenium to endangered razorback suckers (Xyrauchen texanus)

    USGS Publications Warehouse

    Hamilton, S.J.; Holley, K.M.; Buhl, K.J.

    2002-01-01

    A hazard assessment was conducted based on information derived from two reproduction studies conducted with endangered razorback suckers (Xyrauchen texanus) at three sites near Grand Junction, CO, USA. Selenium contamination of the upper and lower Colorado River basin has been documented in water, sediment, and biota in studies by US Department of the Interior agencies and academia. Concern has been raised that this selenium contamination may be adversely affecting endangered fish in the upper Colorado River basin. The reproduction studies with razorback suckers revealed that adults readily accumulated selenium in various tissues including eggs, and that 4.6 ??g/g of selenium in food organisms caused increased mortality of larvae. The selenium hazard assessment protocol resulted in a moderate hazard at the Horsethief site and high hazards at the Adobe Creek and North Pond sites. The selenium hazard assessment was considered conservative because an on-site toxicity test with razorback sucker larvae using 4.6 ??g/g selenium in zooplankton caused nearly complete mortality, in spite of the moderate hazard at Horsethief. Using the margin of uncertainty ratio also suggested a high hazard for effects on razorback suckers from selenium exposure. Both assessment approaches suggested that selenium in the upper Colorado River basin adversely affects the reproductive success of razorback suckers. ?? 2002 Elsevier Science B.V. All rights reserved.

  8. Hazard assessment of selenium to endangered razorback suckers (Xyrauchen texanus).

    PubMed

    Hamilton, Steven J; Holley, Kathleen M; Buhl, Kevin J

    2002-05-27

    A hazard assessment was conducted based on information derived from two reproduction studies conducted with endangered razorback suckers (Xyrauchen texanus) at three sites near Grand Junction, CO, USA. Selenium contamination of the upper and lower Colorado River basin has been documented in water, sediment, and biota in studies by US Department of the Interior agencies and academia. Concern has been raised that this selenium contamination may be adversely affecting endangered fish in the upper Colorado River basin. The reproduction studies with razorback suckers revealed that adults readily accumulated selenium in various tissues including eggs, and that 4.6 microg/g of selenium in food organisms caused increased mortality of larvae. The selenium hazard assessment protocol resulted in a moderate hazard at the Horsethief site and high hazards at the Adobe Creek and North Pond sites. The selenium hazard assessment was considered conservative because an on-site toxicity test with razorback sucker larvae using 4.6 microg/g selenium in zooplankton caused nearly complete mortality, in spite of the moderate hazard at Horsethief. Using the margin of uncertainty ratio also suggested a high hazard for effects on razorback suckers from selenium exposure. Both assessment approaches suggested that selenium in the upper Colorado River basin adversely affects the reproductive success of razorback suckers. PMID:12150431

  9. FUEL ROD ASSEMBLY

    DOEpatents

    Hutter, E.

    1959-09-01

    A cluster of nuclear fuel rods aod a tubular casing through which a coolant flows in heat-change contact with the ruel rods are described. The casting is of trefoil section and carries the fuel rods, each of which has two fin engaging the serrated fins of the other two fuel rods, whereby the fuel rods are held in the casing and are interlocked against relative longitudinal movement.

  10. Which String Breaks? Revisited

    NASA Astrophysics Data System (ADS)

    Frye, Christopher

    2011-03-01

    Many have seen the common introductory physics demonstration in which a heavy ball hangs from a string, with another identical string hanging freely from the ball. When the instructor pulls the bottom string slowly, the top string breaks. However, when the instructor pulls the bottom string very rapidly, the bottom string breaks. This simple experiment is used to demonstrate inertia and Newton's laws. In The Physics Teacher of November 1996, there is an article in which the authors create a model of this problem in an attempt to explain the outcomes quantitatively. However, their analysis gave strange results. Using an improved model, I will show that the results of this demonstration can be obtained using only simple calculations. This work was funded by a RAMP grant from the University of Central Florida.

  11. N = 2 string amplitudes

    SciTech Connect

    Ooguri, H.

    1995-08-01

    In physics, solvable models have played very important roles. Understanding a simple model in detail teaches us a lot about more complicated models in generic situations. Five years ago, C. Vafa and I found that the closed N = 2 string theory, that is a string theory with the N = 2 local supersymmetry on the worldsheet, is classically equivalent to the self-dual Einstein gravity in four spacetime dimensions. Thus this string theory is solvable at the classical level. More recently, we have examined the N = 2 string partition function for spacial compactifications, and computed it to all order in the string perturbation expansion. The fact that such computation is possible at all suggests that the N = 2 string theory is solvable even quantum mechanically.

  12. Tilted string cosmologies

    NASA Astrophysics Data System (ADS)

    Clancy, Dominic; Feinstein, Alexander; Lidsey, James E.; Tavakol, Reza

    1999-04-01

    Global symmetries of the string effective action are employed to generate tilted, homogeneous Bianchi type VIh string cosmologies from a previously known stiff perfect fluid solution to Einstein gravity. The dilaton field is not constant on the surfaces of homogeneity. The future asymptotic state of the models is interpreted as a plane wave and is itself an exact solution to the string equations of motion to all orders in the inverse string tension. An inhomogeneous generalization of the Bianchi type III model is also found.

  13. Heterotic cosmic strings

    SciTech Connect

    Becker, Katrin; Becker, Melanie; Krause, Axel

    2006-08-15

    We show that all three conditions for the cosmological relevance of heterotic cosmic strings, the right tension, stability and a production mechanism at the end of inflation, can be met in the strongly coupled M-theory regime. Whereas cosmic strings generated from weakly coupled heterotic strings have the well-known problems posed by Witten in 1985, we show that strings arising from M5-branes wrapped around 4-cycles (divisors) of a Calabi-Yau in heterotic M-theory compactifications solve these problems in an elegant fashion.

  14. Spontaneous formation of stringlike clusters and smectic sheets for colloidal rods confined in thin wedgelike gaps.

    PubMed

    Maeda, Hideatsu; Maeda, Yoshiko

    2013-08-20

    Monodispersed colloidal rods of β-FeOOH with sizes ranging from 270 to 580 nm in length and 50 to 80 nm in width were synthesized. Narrow wedgelike gaps (0 to 700 nm in height) were formed around the inner bottom edge of the suspension glass cells. Optical microscopic observations revealed the formation of stringlike clusters of the rods and smectic sheets (by spontaneous side-by-side clustering of the strings) in the isotropic phase of the rod suspensions confined in narrow gaps; the electrolyte (HCl) concentrations of the suspensions are 5-40 mM, at which inter-rod interactions are attractive. The strings exhibit different colors that were used to investigate the structures of the strings with the help of interference color theory for thin films. The results are as follows. (1) The rods, lying flat on the gap bottom, are connected side-by-side and stacked upward to form stringlike clusters with different thicknesses depending on the gap height. (2) The stacking numbers (N(sr)) of the rods are estimated to be 1-5. With N(sr) increasing from 2 to 5, the volume fractions (ϕ) of the rods in the strings increased typically from 0.25-0.3 to 0.35-0.42 to reach limiting values (close to the ϕ values of the rods in the bulk smectic phase). (3) Unexpected low-ϕ strings are found in regions with an intermediate height in the gaps. These behaviors of ϕ may be caused by thermal fluctuations of the strings.

  15. Spontaneous formation of stringlike clusters and smectic sheets for colloidal rods confined in thin wedgelike gaps.

    PubMed

    Maeda, Hideatsu; Maeda, Yoshiko

    2013-08-20

    Monodispersed colloidal rods of β-FeOOH with sizes ranging from 270 to 580 nm in length and 50 to 80 nm in width were synthesized. Narrow wedgelike gaps (0 to 700 nm in height) were formed around the inner bottom edge of the suspension glass cells. Optical microscopic observations revealed the formation of stringlike clusters of the rods and smectic sheets (by spontaneous side-by-side clustering of the strings) in the isotropic phase of the rod suspensions confined in narrow gaps; the electrolyte (HCl) concentrations of the suspensions are 5-40 mM, at which inter-rod interactions are attractive. The strings exhibit different colors that were used to investigate the structures of the strings with the help of interference color theory for thin films. The results are as follows. (1) The rods, lying flat on the gap bottom, are connected side-by-side and stacked upward to form stringlike clusters with different thicknesses depending on the gap height. (2) The stacking numbers (N(sr)) of the rods are estimated to be 1-5. With N(sr) increasing from 2 to 5, the volume fractions (ϕ) of the rods in the strings increased typically from 0.25-0.3 to 0.35-0.42 to reach limiting values (close to the ϕ values of the rods in the bulk smectic phase). (3) Unexpected low-ϕ strings are found in regions with an intermediate height in the gaps. These behaviors of ϕ may be caused by thermal fluctuations of the strings. PMID:23876087

  16. Introduction to string field theory

    SciTech Connect

    Lykken, J.; Raby, S.

    1986-01-01

    An action is proposed for an interacting closed bosonic string. Our formalism relies heavily on ideas discussed by Witten for the open bosonic string. The gauge fixed quantum action for the fully interacting open bosonic string is obtained.

  17. Covariant Closed String Coherent States

    SciTech Connect

    Hindmarsh, Mark; Skliros, Dimitri

    2011-02-25

    We give the first construction of covariant coherent closed string states, which may be identified with fundamental cosmic strings. We outline the requirements for a string state to describe a cosmic string, and provide an explicit and simple map that relates three different descriptions: classical strings, light cone gauge quantum states, and covariant vertex operators. The resulting coherent state vertex operators have a classical interpretation and are in one-to-one correspondence with arbitrary classical closed string loops.

  18. Covariant closed string coherent states.

    PubMed

    Hindmarsh, Mark; Skliros, Dimitri

    2011-02-25

    We give the first construction of covariant coherent closed string states, which may be identified with fundamental cosmic strings. We outline the requirements for a string state to describe a cosmic string, and provide an explicit and simple map that relates three different descriptions: classical strings, light cone gauge quantum states, and covariant vertex operators. The resulting coherent state vertex operators have a classical interpretation and are in one-to-one correspondence with arbitrary classical closed string loops. PMID:21405564

  19. Control rod drive

    DOEpatents

    Hawke, Basil C.

    1986-01-01

    A control rod drive uses gravitational forces to insert one or more control rods upwardly into a reactor core from beneath the reactor core under emergency conditions. The preferred control rod drive includes a vertically movable weight and a mechanism operatively associating the weight with the control rod so that downward movement of the weight is translated into upward movement of the control rod. The preferred control rod drive further includes an electric motor for driving the control rods under normal conditions, an electrically actuated clutch which automatically disengages the motor during a power failure and a decelerator for bringing the control rod to a controlled stop when it is inserted under emergency conditions into a reactor core.

  20. Cosmic strings with curvature corrections

    NASA Astrophysics Data System (ADS)

    Boisseau, Bruno; Letelier, Patricio S.

    1992-08-01

    A generic model of string described by a Lagrangian density that depends on the extrinsic curvature of the string worldsheet is studied. Using a system of coordinates adapted to the string world sheet the equation of motion and the energy-momentum tensor are derived for strings evolving in curved spacetime. We find that the curvature corrections may change the relation between the string energy density and the tension. It can also introduce heat propagation along the string. We also find for the Polyakov as well as Nambu strings with a topological term that the open string end points can travel with a speed less than the velocity of light.

  1. Commentary: selenium study on endangered razorback sucker is flawed

    USGS Publications Warehouse

    Hamilton, Steven J.

    2005-01-01

    The razorback sucker (Xyrauchen texanus) is listed as federally endangered throughout its range. A massive recovery effort by the Recovery Implementation Program for Endangered Fish Species in the Upper Colorado River Basin has focused its efforts in the upper Colorado River. The upper Colorado River basin also has two locations that have been identified by the National Irrigation Water Quality Program as having substantial selenium contamination. Selenium is toxic to fishes, affecting reproductive success. Thus, there is concern about potential effects of selenium on the endangered razorback sucker. Two sets of studies have investigated the effects of selenium on razorback suckers, but study results are conflicting. This commentary evaluates studies that claim selenium is not a problem for razorback sucker. We find that study bias was so pervasive that purported conclusions were unwarranted. Contaminated control water, older life stages of fish tested, lack of methodology for analysis of selenium in water, diet, or fish, use of rotifer food, low feeding rates, low growth rates of fish, and improper storage of site waters resulted in an apparent erroneous linkage of high selenium in whole-body residues with no adverse effects.

  2. 21 CFR 870.4420 - Cardiopulmonary bypass cardiotomy return sucker.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cardiopulmonary bypass cardiotomy return sucker. 870.4420 Section 870.4420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... from the chest or heart during cardiopulmonary bypass surgery. (b) Classification. Class...

  3. 21 CFR 870.4420 - Cardiopulmonary bypass cardiotomy return sucker.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cardiopulmonary bypass cardiotomy return sucker. 870.4420 Section 870.4420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... from the chest or heart during cardiopulmonary bypass surgery. (b) Classification. Class...

  4. 21 CFR 870.4420 - Cardiopulmonary bypass cardiotomy return sucker.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass cardiotomy return sucker. 870.4420 Section 870.4420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... from the chest or heart during cardiopulmonary bypass surgery. (b) Classification. Class...

  5. Small nonnative fishes as predators of larval razorback suckers

    USGS Publications Warehouse

    Carpenter, J.; Mueller, G.A.

    2008-01-01

    The razorback sucker (Xyrauchen texanus), an endangered big-river fish of the Colorado River basin, has demonstrated no sustainable recruitment in 4 decades, despite presence of spawning adults and larvae. Lack of adequate recruitment has been attributed to several factors, including predation by nonnative fishes. Substantial funding and effort has been expended on mechanically removing nonnative game fishes, typically targeting large predators. As a result, abundance of larger predators has declined, but the abundance of small nonnative fishes has increased in some areas. We conducted laboratory experiments to determine if small nonnative fishes would consume larval razorback suckers. We tested adults of three small species (threadfin shad, Dorosoma petenense; red shiner, Cyprinella lutrensis; fathead minnow, Pimephales promelas) and juveniles of six larger species (common carp, Cyprinus carpio; yellow bullhead, Ameiurus natalis; channel catfish, Ictalurus punctatus; rainbow trout, Oncorhynchus mykiss; green sunfish, Lepomis cyanellus; bluegill, L. macrochirus). These nonnative fishes span a broad ecological range and are abundant within the historical range of the razorback sucker. All nine species fed on larval razorback suckers (total length, 9-16 mm). Our results suggest that predation by small nonnative fishes could be responsible for limiting recovery of this endangered species.

  6. Piston rod seal

    DOEpatents

    Lindskoug, Stefan

    1984-01-01

    In a piston rod seal of the type comprising a gland through which the piston rod is passed the piston is provided with a sleeve surrounding the piston rod and extending axially so as to axially partly overlap the gland when the piston is in its bottom dead center position.

  7. k-strings as fundamental strings

    NASA Astrophysics Data System (ADS)

    Giataganas, Dimitrios

    2015-05-01

    It has been noticed that the k-string observables can be expressed in terms of the fundamental string ones. We identify a sufficient condition for a generic gravity dual background which when satisfied the mapping can be done. The condition is naturally related to a preserved quantity under the T-dualities acting on the Dp-brane describing the high representation Wilson loops. We also find the explicit relation between the observables of the heavy k-quark and the single quark states. As an application to our generic study and motivated by the fact that the anisotropic theories satisfy our condition, we compute the width of the k-string in these theories to find that the logarithmic broadening is still present, but the total result is affected by the anisotropy of the space.

  8. Progress in string theory

    NASA Astrophysics Data System (ADS)

    Maldacena, Juan Martín

    D-Branes on Calabi-Yau manifolds / Paul S. Aspinwall -- Lectures on AdS/CFT / Juan M. Maldacena -- Tachyon dynamics in open string theory / Ashoke Sen -- TASI/PITP/ISS lectures on moduli and microphysics / Eva Silverstein -- The duality cascade / Matthew J. Strassler -- Perturbative computations in string field theory / Washington Taylor -- Student seminars -- Student participants -- Lecturers, directors, and local organizing committee.

  9. Stable Charged Cosmic Strings

    SciTech Connect

    Weigel, H.; Quandt, M.; Graham, N.

    2011-03-11

    We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius {approx_equal}10{sup -18} m. The vacuum remains stable in our model, because neutral strings are not energetically favored.

  10. Stable charged cosmic strings.

    PubMed

    Weigel, H; Quandt, M; Graham, N

    2011-03-11

    We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius ≈10(-18)  m. The vacuum remains stable in our model, because neutral strings are not energetically favored. PMID:21469786

  11. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.; Rogers, I.

    1961-06-27

    Accurate and controlled drive for the control rod is from an electric motor. A hydraulic arrangement is provided to balance a piston against which a control rod is urged by the application of fluid pressure. The electric motor drive of the control rod for normal operation is made through the aforementioned piston. In the event scramming is required, the fluid pressure urging the control rod against the piston is relieved and an opposite fluid pressure is applied. The lack of mechanical connection between the electric motor and control rod facilitates the scramming operation.

  12. CRUCIFORM CONTROL ROD JOINT

    DOEpatents

    Thorp, A.G. II

    1962-08-01

    An invention is described which relates to nuclear reactor control rod components and more particularly to a joint between cruciform control rod members and cruciform control rod follower members. In one embodiment this invention provides interfitting crossed arms at adjacent ends of a control rod and its follower in abutting relation. This holds the members against relative opposite longitudinal movement while a compression member keys the arms against relative opposite rotation around a common axis. Means are also provided for centering the control rod and its follower on a common axis and for selectively releasing the control rod from its follower for the insertion of a replacement of the control rod and reuse of the follower. (AEC)

  13. Universality and string theory

    NASA Astrophysics Data System (ADS)

    Bachlechner, Thomas Christian

    The first run at the Large Hadron Collider has deeply challenged conventional notions of naturalness, and CMB polarization experiments are about to open a new window to early universe cosmology. As a compelling candidate for the ultraviolet completion of the standard model, string theory provides a prime opportunity to study both early universe cosmology and particle physics. However, relating low energy observations to ultraviolet physics requires knowledge of the metastable states of string theory through the study of vacua. While it is difficult to directly obtain infrared data from explicit string theory constructions, string theory imposes constraints on low energy physics. The study of ensembles of low energy theories consistent with ultra-violet constraints provides insight on generic features we might expect to occur in string compactifications. In this thesis we present a statistical treatment of vacuum stability and vacuum properties in the context of random supergravity theories motivated by string theory. Early universe cosmology provides another avenue to high energy physics. From the low energy perspective large field inflation is typically considered highly unnatural: the scale relevant for the diameter of flat regions in moduli space is sub-Planckian in regions of perturbative control. To approach this problem, we consider generic Calabi-Yau compactifications of string theory and find that super-Planckian diameters of axion fundamental domains in fact arise generically. We further demonstrate that such super-Planckian flat regions are plausibly consistent with theWeak Gravity Conjecture.

  14. Supersymmetry and String Theory

    NASA Astrophysics Data System (ADS)

    Dine, Michael

    2016-01-01

    Preface to the first edition; Preface to the second edition; A note on choice of metric; Text website; Part I. Effective Field Theory: The Standard Model, Supersymmetry, Unification: 1. Before the Standard Model; 2. The Standard Model; 3. Phenomenology of the Standard Model; 4. The Standard Model as an effective field theory; 5. Anomalies, instantons and the strong CP problem; 6. Grand unification; 7. Magnetic monopoles and solitons; 8. Technicolor: a first attempt to explain hierarchies; Part II. Supersymmetry: 9. Supersymmetry; 10. A first look at supersymmetry breaking; 11. The Minimal Supersymmetric Standard Model; 12. Supersymmetric grand unification; 13. Supersymmetric dynamics; 14. Dynamical supersymmetry breaking; 15. Theories with more than four conserved supercharges; 16. More supersymmetric dynamics; 17. An introduction to general relativity; 18. Cosmology; 19. Astroparticle physics and inflation; Part III. String Theory: 20. Introduction; 21. The bosonic string; 22. The superstring; 23. The heterotic string; 24. Effective actions in ten dimensions; 25. Compactification of string theory I. Tori and orbifolds; 26. Compactification of string theory II. Calabi–Yau compactifications; 27. Dynamics of string theory at weak coupling; 28. Beyond weak coupling: non-perturbative string theory; 29. Large and warped extra dimensions; 30. The landscape: a challenge to the naturalness principle; 31. Coda: where are we headed?; Part IV. The Appendices: Appendix A. Two-component spinors; Appendix B. Goldstone's theorem and the pi mesons; Appendix C. Some practice with the path integral in field theory; Appendix D. The beta function in supersymmetric Yang–Mills theory; References; Index.

  15. Strings without supersymmetry

    NASA Astrophysics Data System (ADS)

    Adams, Allan Wilfred

    This dissertation examines the condensation of closed string tachyons in nonsupersymmetric spacetimes. Closed string tachyons signal instabilities of the spacetime background which make perturbation theory around the chosen vacuum inconsistent. Non-perturbative techniques developed in studying supersymmetric geometries provide a powerful set of tools with which to re-examine the classic problem of closed string tachyons. Such approaches allow remarkably controlled and complete descriptions of the condensation of closed string tachyons in a broad class of non-supersymmetric theories. The text begins with a discussion of closed string tachyons in non-supersymmetric orbifolds of AdS5 x S 5, using the orbifolded dual CFT to study non-perturbative features of the tachyonic instabilities in the orbifolded spacetime. We then discuss localized closed string tachyons in orbifolds of flat space which break spacetime supersymmetry only at isolated curvature singularities. Using worldsheet and D-probe techniques to follow these systems beyond perturbation theory, we show that these localized tachyons resolve the spacetime as they condense, leading generically to smooth and asymptotically supersymmetric spacetimes. Finally, we discuss a proposal for removing these instabilities from the perturbative string which is motivated by our results on non-supersymmetric orbifolds of the AdS/CFT correspondence.

  16. Hydraulic well pumping apparatus

    SciTech Connect

    Wright, C.P.

    1987-03-03

    This patent describes a hydraulic powered well pumping apparatus for operation of a sucker rod well pump in a well borehole, the apparatus comprising: (a) an elongate polished rod having upper and lower ends, the rod being aligned above and adapted to connect to a string of sucker rods in a well borehole therebelow; (b) an adjustably positioned sleeve means aligned above and enclosing a portion of the polished rod and having a shorter length than the polished rod to enable the polished rod to extend above the sleeve means and below the sleeve means for connection to the string of sucker rods in the well borehole; (c) an axially hollow upstanding cylinder slideably receiving the sleeve means therethrough and enclosing a piston therein, the piston being: (1) moved on admitting hydraulic oil to the cylinder, and (2) joined to the sleeve means for moving the sleeve means and thereby moving the polished rod; (d) means for mounting the upstanding cylinder directly aligned with and above a casing at the top of a well adapted to have a sucker rod string positioned therein; (e) means for adjusting the stroke length imparted to the sucker rod string between minimum and maximum stroke lengths; and (f) means for adjusting the location of the sleeve means relative to the polished rod to vary the relative length of polished rod below the sleeve means and wherein a portion of the polished rod extends above the sleeve means dependent on the relative respective portions thereof.

  17. Cosmological cosmic strings

    NASA Technical Reports Server (NTRS)

    Gregory, Ruth

    1988-01-01

    The effect of an infinite cosmic string on a cosmological background is investigated. It is found that the metric is approximately a scaled version of the empty space string metric, i.e., conical in nature. Results are used to place bounds on the amount of cylindrical gravitational radiation currently emitted by such a string. The gravitational radiation equations are then analyzed explicitly and it is shown that even initially large disturbances are rapidly damped as the expansion proceeds. The implications of the gravitational radiation background and the limitations of the quadrupole formula are discussed.

  18. Final Report: "Strings 2014"

    SciTech Connect

    Witten, Edward

    2015-10-21

    The Strings 2014 meeting was held at Princeton University June 23-27, 2014, co-sponsored by Princeton University and the Institute for Advanced Study. The goal of the meeting was to provide a stimulating and up-to-date overview of research in string theory and its relations to other areas of physics and mathematics, ranging from geometry to quantum field theory, condensed matter physics, and more. This brief report lists committee members and speakers but contains no scientific information. Note that the talks at Strings 2014 were videotaped and are available on the conference website: http://physics.princeton.edustrings2014/Talk_titles.shtml.

  19. Supermassive cosmic string compactifications

    SciTech Connect

    Blanco-Pillado, Jose J.; Reina, Borja; Sousa, Kepa; Urrestilla, Jon E-mail: borja.reina@ehu.es E-mail: jon.urrestilla@ehu.es

    2014-06-01

    The space-time dimensions transverse to a static straight cosmic string with a sufficiently large tension (supermassive cosmic strings) are compact and typically have a singularity at a finite distance form the core. In this paper, we discuss how the presence of multiple supermassive cosmic strings in the 4d Abelian-Higgs model can induce the spontaneous compactification of the transverse space and explicitly construct solutions where the gravitational background becomes regular everywhere. We discuss the embedding of this model in N = 1 supergravity and show that some of these solutions are half-BPS, in the sense that they leave unbroken half of the supersymmetries of the model.

  20. Colonial waterbird predation on Lost River and Shortnose suckers in the Upper Klamath Basin

    USGS Publications Warehouse

    Evans, Allen F.; Hewitt, David A.; Payton, Quinn; Cramer, Bradley M.; Collis, Ken; Roby, Daniel D.

    2016-01-01

    We evaluated predation on Lost River Suckers Deltistes luxatus and Shortnose Suckers Chasmistes brevirostris by American white pelicans Pelecanus erythrorhynchos and double-crested cormorants Phalacrocorax auritus nesting at mixed-species colonies in the Upper Klamath Basin of Oregon and California during 2009–2014. Predation was evaluated by recovering (detecting) PIT tags from tagged fish on bird colonies and calculating minimum predation rates, as the percentage of available suckers consumed, adjusted for PIT tag detection probabilities but not deposition probabilities (i.e., probability an egested tag was deposited on- or off-colony). Results indicate that impacts of avian predation varied by sucker species, age-class (adult, juvenile), bird colony location, and year, demonstrating dynamic predator–prey interactions. Tagged suckers ranging in size from 72 to 730 mm were susceptible to cormorant or pelican predation; all but the largest Lost River Suckers were susceptible to bird predation. Minimum predation rate estimates ranged annually from <0.1% to 4.6% of the available PIT-tagged Lost River Suckers and from <0.1% to 4.2% of the available Shortnose Suckers, and predation rates were consistently higher on suckers in Clear Lake Reservoir, California, than on suckers in Upper Klamath Lake, Oregon. There was evidence that bird predation on juvenile suckers (species unknown) in Upper Klamath Lake was higher than on adult suckers in Upper Klamath Lake, where minimum predation rates ranged annually from 5.7% to 8.4% of available juveniles. Results suggest that avian predation is a factor limiting the recovery of populations of Lost River and Shortnose suckers, particularly juvenile suckers in Upper Klamath Lake and adult suckers in Clear Lake Reservoir. Additional research is needed to measure predator-specific PIT tag deposition probabilities (which, based on other published studies, could increase predation rates presented herein by a factor of roughly 2

  1. Strings at finite temperature

    SciTech Connect

    Arago C. de; Bazeia, D.; Eboli, O.J.P.; Marques, G.C.

    1985-12-15

    We obtain a semiclassical evaluation of the temperature for which the free energy of the strings of spontaneously broken scalar electrodynamics vanishes. We argue that, above this temperature, these objects should play a significant physical role.

  2. Universality in string interactions

    NASA Astrophysics Data System (ADS)

    Huang, Yu-tin; Schlotterer, Oliver; Wen, Congkao

    2016-09-01

    In this note, we provide evidence for universality in the low-energy expansion of tree-level string interactions. More precisely, in the α'-expansion of tree-level scattering amplitudes, we conjecture that the leading transcendental coefficient at each order in α' is universal for all perturbative string theories. We have checked this universality up to seven points and trace its origin to the ability to restructure the disk integrals of open bosonic string into those of the superstring. The accompanying kinematic functions have the same low-energy limit and do not introduce any transcendental numbers in their α'-corrections. Universality in the closed-string sector then follows from KLT-relations.

  3. Subsurface drill string

    DOEpatents

    Casper, William L.; Clark, Don T.; Grover, Blair K.; Mathewson, Rodney O.; Seymour, Craig A.

    2008-10-07

    A drill string comprises a first drill string member having a male end; and a second drill string member having a female end configured to be joined to the male end of the first drill string member, the male end having a threaded portion including generally square threads, the male end having a non-threaded extension portion coaxial with the threaded portion, and the male end further having a bearing surface, the female end having a female threaded portion having corresponding female threads, the female end having a non-threaded extension portion coaxial with the female threaded portion, and the female end having a bearing surface. Installation methods, including methods of installing instrumented probes are also provided.

  4. A new approach to the analysis of deviated rod-pumped wells

    SciTech Connect

    Xu, J.

    1994-12-31

    This paper presents the derivation and numerical solutions of a 3D dynamic model for analyzing the behavior of sucker-rod pumping installations in deviated wells. Using differential geometry and variational methods, the rod dynamics in deviated wells is presented by the set of six coupled differential equations with their boundary conditions. The paper describes the fundamental assumptions and simplifications which can be used in the numerical solution. A computer program based on the model is developed and applied to determine the downhole conditions and to predict the rod behavior in the deviated well. A number of wells are examined. Good agreement is shown by comparing the computed results with the field measurements.

  5. Instantons in string theory

    SciTech Connect

    Ahlén, Olof

    2015-12-17

    These proceedings from the second Caesar Lattes meeting in Rio de Janeiro 2015 are a brief introduction to how automorphic forms appear in the low energy effective action of maximally supersymmetric string theory. The explicit example of the R{sup 4}-interaction of type IIB string theory in ten dimensions is discussed. Its Fourier expansion is interpreted in terms of perturbative and non-perturbative contributions to the four graviton amplitude.

  6. BIOLOGY OF THE LEECH ACTINOBDELLA INEQUIANNULATA MOORE, 1901 (ANNELIDA: HIRUDINEA: RHYNCHOBDELLIDA: GLOSSIPHONIIDAE), PARASITIC ON THE WHITE SUCKER, CATOSTOMUS COMMERSONI LACEPEDE, 1803 AND THE LONGNOSE SUCKER, CATOSTOMUS CATOSTOMUS FORSTER, 1773, IN ALGONQUIN PROVINCIAL PARK, ONTARIO, CANADA

    EPA Science Inventory

    Actinobdella inequiannulata was found on the white sucker, Catostomus commersoni, and less frequently on the longnose sucker, Catostomus catostomus, in Algonquin Provincial Park, Ontario, Canada. Catostomus commersoni parasitized with Act. inequiannulata was collected from July ...

  7. Pull rod assembly

    DOEpatents

    Cioletti, O.C.

    1988-04-21

    A pull rod assembly comprising a pull rod having three peripheral grooves, a piston device including an adaptor ring and a seal ring, said piston device being mounted on the pull rod by a split ring retainer situated in one groove and extending into an interior groove in the adaptor and a resilient split ring retained in another groove and positioned to engage the piston device and to retain the seal on its adaptor.

  8. Pull rod assembly

    DOEpatents

    Cioletti, Olisse C.

    1990-01-01

    A pull rod assembly comprising a pull rod having three peripheral grooves, a piston device including an adaptor ring and a seal ring, said piston device being mounted on the pull rod by a split ring retainer situated in one groove and extending into an interior groove in the adaptor and a resilient split ring retained in another groove and positioned to engage the piston device and to retain the seal on its adaptor.

  9. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.

    1960-05-24

    BS>A drive mechanism was invented for the control rod of a nuclear reactor. Power is provided by an electric motor and an outside source of fluid pressure is utilized in conjunction with the fluid pressure within the reactor to balance the loadings on the motor. The force exerted on the drive mechanism in the direction of scramming the rod is derived from the reactor fluid pressure so that failure of the outside pressure source will cause prompt scramming of the rod.

  10. Pull rod assembly

    SciTech Connect

    Cioletti, O.C.

    1990-05-22

    This patent describes a pull rod assembly. It comprises: a pull rod having three peripheral grooves, a piston device including an adaptor ring and a seal ring. The piston device is mounted on the pull rod by a split ring retainer situated in one groove and extending into an interior groove in the adaptor and a resilient split ring retained in another groove and positioned to engage the piston device and to retain the seal on its adaptor.

  11. Instabilities of twisted strings

    NASA Astrophysics Data System (ADS)

    Forgács, Péter; Lukács, Árpád

    2009-12-01

    A linear stability analysis of twisted flux-tubes (strings) in an SU(2) semilocal theory — an Abelian-Higgs model with two charged scalar fields with a global SU(2) symmetry — is carried out. Here the twist refers to a relative phase between the two complex scalars (with linear dependence on, say, the z coordinate), and importantly it leads to a global current flowing along the the string. Such twisted strings bifurcate with the Abrikosov-Nielsen-Olesen (ANO) solution embedded in the semilocal theory. Our numerical investigations of the small fluctuation spectrum confirm previous results that twisted strings exhibit instabilities whose amplitudes grow exponentially in time. More precisely twisted strings with a single magnetic flux quantum admit a continuous family of unstable eigenmodes with harmonic z dependence, indexed by a wavenumber kin[-km, km]. Carrying out a perturbative semi-analytic analysis of the bifurcation, it is found that the purely numerical results are very well reproduced. This way one obtains not only a good qualitative description of the twisted solutions themselves as well as of their instabilities, but also a quantitative description of the numerical results. Our semi-analytic results indicate that in close analogy to the known instability of the embedded ANO vortex a twisted string is also likely to expand in size caused by the spreading out of its magnetic flux.

  12. Twisted superconducting semilocal strings

    NASA Astrophysics Data System (ADS)

    Forgács, Péter; Reuillon, Sébastien; Volkov, Mikhail S.

    2006-09-01

    A new class of twisted, current carrying, stationary, straight string solutions having finite energy per unit length is constructed numerically in an extended Abelian Higgs model with global SU(2) symmetry. The new solutions correspond to deformations of the embedded Abrikosov Nielsen Olesen (ANO) vortices by a twist—a relative coordinate dependent phase between the two Higgs fields. The twist induces a global current flowing through the string, and the deformed solutions bifurcate with the ANO vortices in the limit of vanishing current. For each value of the winding number n=1,2,… (determining the magnetic flux through the plane orthogonal to the string) there are n distinct, two-parametric families of solutions. One of the continuously varying parameters is the twist, or the corresponding current, the other one can be chosen to be the momentum of the string. For fixed values of the momentum and twist, the n distinct solutions have different energies and can be viewed as a lowest energy “fundamental” string and its n-1 “excitations” characterized by different values of their “polarization”. The latter is defined as the ratio of the angular momentum of the vortex and its momentum. In their rest frame the twisted vortices have lower energy than the embedded ANO vortices and could be of considerable importance in various physical systems (from condensed matter to cosmic strings).

  13. Hydroball string sensing system

    DOEpatents

    Hurwitz, Michael J.; Ekeroth, Douglas E.; Squarer, David

    1991-01-01

    A hydroball string sensing system for a nuclear reactor that includes stainless tubes positioned to guide hydroball strings into and out of the nuclear reactor core. A sensor such as an ultrasonic transducer transmitter and receiver is positioned outside of the nuclear reactor core and adjacent to the tube. The presence of an object such a bullet member positioned at an end a hydroball string, or any one of the hydroballs interrupts the transmission of ultrasound from the transmitter to the receiver. Alternatively, if the bullet member and hydroballs include a ferritic material, either a Hall effect sensor or other magnetic field sensors such as a magnetic field rate of change sensor can be used to detect the location and position of a hydroball string. Placing two sensors along the tube with a known distance between the sensors enables the velocity of a hydroball string to be determined. This determined velocity can be used to control the flow rate of a fluid within the tube so as to control the velocity of the hydroball string.

  14. BIOLOGY AND OCCURRENCE OF THE LEECH, ACTINOBDELLA INEQUIANNULATA (ANNELIDA: HIRUDINEA: GLOSSIPHONIIDAE) PARASITIC ON TWO SPECIES OF SUCKERS

    EPA Science Inventory

    Actinobdella inequiannulata was found on the white sucker, Catostomus commersoni, and less frequently on the longnose sucker, Catostomus catostomus, in Algonquin Provincial Park, Ontario, Canada. This study established the presence of only one species of leech, Actinobdela inequ...

  15. HP41C/CV program computes torque factors for any rod pumping unit to spot problems early

    SciTech Connect

    Rdissi, A.

    1984-01-01

    The principal artificial lift method in U.S. oil fields is sucker-rod pumping, which encompasses over 85% of all producing wells. Dynamometer tests have never been run on the majority of these wells. A dynamometer is an electromechanical device which measures load vs. position of the polish rod at any given point in a stroke cycle. The graphical representation of the polish rod load vs. its position is called a dynagraph or dynamometer card. The components of a dynamometer system are: Although torque factors are furnished by some manufactureers for various size units, exact unit dimensions may vary slightly; therefore, more accurate torque factors should be calculated. This program offers the user a quick, accurate evaluation of gear box operating conditions; thus minimizing the risk of exposing rod pumping units to overtorque and eliminating tedious hand calculations.

  16. Haptic distal spatial perception mediated by strings: haptic "looming".

    PubMed

    Cabe, Patrick A

    2011-10-01

    Five experiments tested a haptic analog of optical looming, demonstrating string-mediated haptic distal spatial perception. Horizontally collinear hooks supported a weighted string held taut by a blindfolded participant's finger midway between the hooks. At the finger, the angle between string segments increased as the finger approached collinearity with the hooks, just as the optical angle subtended by an approaching object increases. The vertical force component at the finger is potentially informative for perception, approaching zero at finger-hook collinearity. In Experiment 1, participants judged hook height reasonably accurately. To retain force relationships but eliminate immediate skin contact, Experiment 2 employed a hand-held rod; results replicated those of Experiment 1. Experiment 3 replicated Experiment 2 using a ring instead of a rod. In all three experiments, estimated hook height closely paralleled actual height, r > .9. Experiments 4 and 5 showed that participants could project impending finger-hook collinearity when finger contact with the string was interrupted during its traverse. Perceivers' estimate errors were nearly perfectly predicted by height-force ratio relationships (Rs > .96). Outcomes are related to optical and acoustic looming, dynamic touch, tau theory, and Gibsonian perceptual theory.

  17. Haptic distal spatial perception mediated by strings: haptic "looming".

    PubMed

    Cabe, Patrick A

    2011-10-01

    Five experiments tested a haptic analog of optical looming, demonstrating string-mediated haptic distal spatial perception. Horizontally collinear hooks supported a weighted string held taut by a blindfolded participant's finger midway between the hooks. At the finger, the angle between string segments increased as the finger approached collinearity with the hooks, just as the optical angle subtended by an approaching object increases. The vertical force component at the finger is potentially informative for perception, approaching zero at finger-hook collinearity. In Experiment 1, participants judged hook height reasonably accurately. To retain force relationships but eliminate immediate skin contact, Experiment 2 employed a hand-held rod; results replicated those of Experiment 1. Experiment 3 replicated Experiment 2 using a ring instead of a rod. In all three experiments, estimated hook height closely paralleled actual height, r > .9. Experiments 4 and 5 showed that participants could project impending finger-hook collinearity when finger contact with the string was interrupted during its traverse. Perceivers' estimate errors were nearly perfectly predicted by height-force ratio relationships (Rs > .96). Outcomes are related to optical and acoustic looming, dynamic touch, tau theory, and Gibsonian perceptual theory. PMID:21688938

  18. FUEL ROD CLUSTERS

    DOEpatents

    Schultz, A.B.

    1959-08-01

    A cluster of nuclear fuel rods and a tubular casing therefor through which a coolant flows in heat-exchange contact with the fuel rods is described. The fuel rcds are held in the casing by virtue of the compressive force exerted between longitudinal ribs of the fuel rcds and internal ribs of the casing or the internal surfaces thereof.

  19. Rod sequence advisor

    SciTech Connect

    Wood, R.M. ); Lu, Yi ); Furia, R.V.; Thompson, R.J. ); Lin, Ching-lu )

    1992-01-01

    During startup and power shaping maneuvers of boiling water reactors (BWR's), control rods are sequentially withdrawn from the reactor core. The withdrawal sequences determine the overall reactor power and the local core power density and are based on the knowledge of station engineers. It is important that the control rods are withdrawn in such a manner that the local power level does not become excessive while the desired reactor power is generated. Rules that constrain the relative positions of control rod groups have been developed to do this. While these rules are relatively simple, applying them to all possible movements of the 17 control rod groups in a typical BWR is complex and time consuming. SMARTRODS, is a rule based pilot expert system, was developed in LISP for the determination of the rod sequences.

  20. M-Strings

    NASA Astrophysics Data System (ADS)

    Haghighat, Babak; Iqbal, Amer; Kozçaz, Can; Lockhart, Guglielmo; Vafa, Cumrun

    2015-03-01

    M2 branes suspended between adjacent parallel M5 branes lead to light strings, the `M-strings'. In this paper we compute the elliptic genus of M-strings, twisted by maximally allowed symmetries that preserve 2 d (2, 0) supersymmetry. In a codimension one subspace of parameters this reduces to the elliptic genus of the (4, 4) supersymmetric A n-1 quiver theory in 2 d. We contrast the elliptic genus of N M-strings with the (4, 4) sigma model on the N-fold symmetric product of . For N = 1 they are the same, but for N > 1 they are close, but not identical. Instead the elliptic genus of (4, 4) N M-strings is the same as the elliptic genus of (4, 0) sigma models on the N-fold symmetric product of , but where the right-moving fermions couple to a modification of the tangent bundle. This construction arises from a dual A n-1 quiver 6 d gauge theory with U(1) gauge groups. Moreover, we compute the elliptic genus of domain walls which separate different numbers of M2 branes on the two sides of the wall.

  1. PT-symmetric strings

    SciTech Connect

    Amore, Paolo; Fernández, Francisco M.; Garcia, Javier; Gutierrez, German

    2014-04-15

    We study both analytically and numerically the spectrum of inhomogeneous strings with PT-symmetric density. We discuss an exactly solvable model of PT-symmetric string which is isospectral to the uniform string; for more general strings, we calculate exactly the sum rules Z(p)≡∑{sub n=1}{sup ∞}1/E{sub n}{sup p}, with p=1,2,… and find explicit expressions which can be used to obtain bounds on the lowest eigenvalue. A detailed numerical calculation is carried out for two non-solvable models depending on a parameter, obtaining precise estimates of the critical values where pair of real eigenvalues become complex. -- Highlights: •PT-symmetric Hamiltonians exhibit real eigenvalues when PT symmetry is unbroken. •We study PT-symmetric strings with complex density. •They exhibit regions of unbroken PT symmetry. •We calculate the critical parameters at the boundaries of those regions. •There are exact real sum rules for some particular complex densities.

  2. Topics in string theory

    SciTech Connect

    Liu, J.

    1988-01-01

    The author discusses several aspects of string theory. First, he calculates the vacuum amplitude of un-oriented open and closed string theory using Polyakov formalism. He argues that the volume of the Mobius Group should be renormalized, and solve a minor paradox. Second, he gives an example of a membrane whose effective action is the generalization of Green-Schwarz covariant superstring action. As a by-product, he shows that is also provides an example of partially broken global supersymmetry. The rest of the dissertation is devoted to the study of string field theory in terms of the renormalization group approach. He emphasizes the pivotal role of the conformal invariance in string theory. He proposes the generalized Wilsonian conformal renormalization group equation of 2-dimensional quantum field theory as the field equation for string field theory following Banks and Martinec. He then finds general solutions to the linearized equation on the flat back-ground and its correspondence to all the physical vertex operators. He also makes detailed study of massless modes and offer some remarks about how gauge invariance arise in this approach. Finally, he solves the full nonlinear equation iteratively in terms of the solutions to the linearized equation and extract the Virasoro-Shapiro amplitudes from them.

  3. Rod Photoreceptors Detect Rapid Flicker

    ERIC Educational Resources Information Center

    Conner, J. D.; MacLeod, Donald I. A.

    1977-01-01

    Rod-isolation techniques show that light-adapted human rods detect flicker frequencies as high as 28 hertz, and that the function relating rod critical flicker frequency to stimulus intensity contains two distinct branches. (MLH)

  4. Development of a new irrigation sucker for microneurosurgery--technical note.

    PubMed

    Miyake, Hiroji; Tsuji, Masao; Hiramoto, Naoyuki; Ukita, Tohru; Ohmura, Takehisa

    2004-08-01

    A new irrigation sucker (Delta Irrigation Sucker) was designed for microneurosurgery. The Delta Irrigation Sucker has a unique trigonal pyramid-shape thumb piece, providing a very stable grip. Irrigation is achieved easily by pushing a small button just behind the pressure-regulating pore. Stable hold of the sucker and easy handling of the irrigation button enable irrigation without unsteadiness of the sucker. The Delta Irrigation Sucker is available in six sizes, with diameters from 1.5 mm to 4.0 mm at 0.5 mm intervals. Irrigation force is provided by a pressure bag, and a normal sterile transfusion set can be used as the irrigation circuit. The Delta Irrigation Sucker was used in 20 cases of clipping for ruptured cerebral aneurysm, five cases of tumor resection, and three cases of anterior clinoidectomy and opening of the internal auditory meatus. Subarachnoid clot was easily removed and the bleeding points were easily confirmed. Irrigation, controlled by natural finger movement, did not cause unsteadiness of the sucker. PMID:15508355

  5. String radiative backreaction

    SciTech Connect

    Battye, R.A.; Shellard, E.P. |

    1995-12-01

    We discuss radiative backreaction for global strings described by the Kalb-Ramond action with an analogous derivation to that for the point electron in classical electrodynamics. We show how local corrections to the equations of motion allow one to separate the self-field of the string from that of the radiation field. Modifications to this {open_quote}{open_quote}local backreaction approximation{close_quote}{close_quote} circumvent the runaway solutions, allowing these corrections to be used to evolve string trajectories numerically. Comparisons are made with analytic and numerical radiation calculations from previous work and the merits and limitations of this approach are discussed. {copyright} {ital 1995 The American Physical Society.}

  6. Tensionless strings from worldsheet symmetries

    NASA Astrophysics Data System (ADS)

    Bagchi, Arjun; Chakrabortty, Shankhadeep; Parekh, Pulastya

    2016-01-01

    We revisit the construction of the tensionless limit of closed bosonic string theory in the covariant formulation in the light of Galilean conformal symmetry that rises as the residual gauge symmetry on the tensionless worldsheet. We relate the analysis of the fundamentally tensionless theory to the tensionless limit that is viewed as a contraction of worldsheet coordinates. Analysis of the quantum regime uncovers interesting physics. The degrees of freedom that appear in the tensionless string are fundamentally different from the usual string states. Through a Bogoliubov transformation on the worldsheet, we link the tensionless vacuum to the usual tensile vacuum. As an application, we show that our analysis can be used to understand physics of strings at very high temperatures and propose that these new degrees of freedom are naturally connected with the long-string picture of the Hagedorn phase of free string theory. We also show that tensionless closed strings behave like open strings.

  7. Probing the String Landscape

    ScienceCinema

    Keith Dienes

    2016-07-12

    We are currently in the throes of a potentially huge paradigm shift in physics. Motivated by recent developments in string theory and the discovery of the so-called "string landscape", physicists are beginning to question the uniqueness of fundamental theories of physics and the methods by which such theories might be understood and investigated. In this colloquium, I will give a non-technical introduction to the nature of this paradigm shift and how it developed. I will also discuss some of the questions to which it has led, and the nature of the controversies it has spawned.

  8. Probing the String Landscape

    SciTech Connect

    Keith Dienes

    2009-12-01

    We are currently in the throes of a potentially huge paradigm shift in physics. Motivated by recent developments in string theory and the discovery of the so-called "string landscape", physicists are beginning to question the uniqueness of fundamental theories of physics and the methods by which such theories might be understood and investigated. In this colloquium, I will give a non-technical introduction to the nature of this paradigm shift and how it developed. I will also discuss some of the questions to which it has led, and the nature of the controversies it has spawned.

  9. Cosmic strings and galaxy formation

    NASA Technical Reports Server (NTRS)

    Bertschinger, Edmund

    1989-01-01

    The cosmogonical model proposed by Zel'dovich and Vilenkin (1981), in which superconducting cosmic strings act as seeds for the origin of structure in the universe, is discussed, summarizing the results of recent theoretical investigations. Consideration is given to the formation of cosmic strings, the microscopic structure of strings, gravitational effects, cosmic string evolution, and the formation of galaxies and large-scale structure. Simulation results are presented in graphs, and several outstanding issues are listed and briefly characterized.

  10. Packing tube assembly for pumping wells

    SciTech Connect

    Towner, G.F.; Carter, C.A.

    1987-09-22

    A packing tube assembly for replacing a conventional stuffing box is described. The packing tube assembly comprising: a packing tube; a rod adaptor adapted to be coupled between the polished rod and the sucker rod string and adapted to extend throughout the packing tube when positioned therein; compressible packing means on the rod adaptor adapted to provide a seal between the rod adaptor and the packing tube when the rod adaptor is in position within the packing tube; stabilizing means on the rod adaptor adapted to engage the packing tube to stabilize the rod adaptor within the packing tube during operation; and a mounting bushing connected to the top of the packing tube and adapted to be threaded into the pumping tee to secure the packing tube position within the production tubing string. A method of converting a conventional stuffing box-equipped pumping well to a packing tube-equipped well is described. It consists of: disconnecting the polished rod of the pumping well from the sucker rod string while suspending the sucker rod string within the well by the use of slips; unthreading the conventional stuffing box from the pumping tee of the well and removing the stuffing box; attaching the polished rod to the upper end of a rod adaptor of a packing tube assembly, inserting the rod adaptor with the polished rod attached into the packing tube of the packing tube assembly; aligning the packing tube assembly with the sucker rod string; connecting the lower end of the rod adaptor to the sucker rod string; removing the slips and lowering the packer tube assembly through the pumping tee; and connecting the upper end of the packing tube to the pumping tee.

  11. Embellished String Prints. Cover Story.

    ERIC Educational Resources Information Center

    Smith, Mary Ruth

    1999-01-01

    Focuses on a printmaking activity in which students create embellished string prints using the relief process of string glued to chip board. Explains that string prints can easily be embellished with oil pastels. Provides a description of the procedure and a list of materials and methods. (CMK)

  12. String Theory and Gauge Theories

    SciTech Connect

    Maldacena, Juan

    2009-02-20

    We will see how gauge theories, in the limit that the number of colors is large, give string theories. We will discuss some examples of particular gauge theories where the corresponding string theory is known precisely, starting with the case of the maximally supersymmetric theory in four dimensions which corresponds to ten dimensional string theory. We will discuss recent developments in this area.

  13. Control rod driveline and grapple

    DOEpatents

    Germer, John H.

    1987-01-01

    A control rod driveline and grapple is disclosed for placement between a control rod drive and a nuclear reactor control rod containing poison for parasitic neutron absorption required for reactor shutdown. The control rod is provided with an enlarged cylindrical handle which terminates in an upwardly extending rod to provide a grapple point for the driveline. The grapple mechanism includes a tension rod which receives the upwardly extending handle and is provided with a lower annular flange. A plurality of preferably six grapple segments surround and grip the control rod handle. Each grapple rod segment grips the flange on the tension rod at an interior upper annular indentation, bears against the enlarged cylindrical handle at an intermediate annulus and captures the upwardly flaring frustum shaped handle at a lower and complementary female segment. The tension rods and grapple segments are surrounded by and encased within a cylinder. The cylinder terminates immediately and outward extending annulus at the lower portion of the grapple segments. Excursion of the tension rod relative to the encasing cylinder causes rod release at the handle by permitting the grapple segments to pivot outwardly and about the annulus on the tension rod so as to open the lower defined frustum shaped annulus and drop the rod. Relative movement between the tension rod and cylinder can occur either due to electromagnetic release of the tension rod within defined limits of travel or differential thermal expansion as between the tension rod and cylinder as where the reactor exceeds design thermal limits.

  14. Cosmic D-strings as axionic D-term strings

    NASA Astrophysics Data System (ADS)

    Blanco-Pillado, Jose J.; Dvali, Gia; Redi, Michele

    2005-11-01

    In this work we derive nonsingular BPS string solutions from an action that captures the essential features of a D-brane anti-D-brane system compactified to four dimensions. The model we consider is a supersymmetric Abelian Higgs model with a D-term potential coupled to an axion-dilaton multiplet. The strings in question are axionic D-term strings which we identify with the D-strings of type II string theory. In this picture the Higgs field represents the open string tachyon of the D-D¯ pair and the axion is dual to a Ramond-Ramond form. The crucial term allowing the existence of nonsingular BPS strings is the Fayet-Iliopoulos term, which is related to the tensions of the D-string and of the parent branes. Despite the presence of the axion, the strings are BPS and carry finite energy, due to the fact that the space gets very slowly decompactified away from the core, screening the long range axion field (or equivalently the theory approaches an infinitely weak 4D coupling). Within our 4D effective action we also identify another class of BPS string solutions (s-strings) which have no ten-dimensional analog, and can only exist after compactification.

  15. Cosmic D-strings as axionic D-term strings

    SciTech Connect

    Blanco-Pillado, Jose J.; Dvali, Gia; Redi, Michele

    2005-11-15

    In this work we derive nonsingular BPS string solutions from an action that captures the essential features of a D-brane-anti-D-brane system compactified to four dimensions. The model we consider is a supersymmetric Abelian Higgs model with a D-term potential coupled to an axion-dilaton multiplet. The strings in question are axionic D-term strings which we identify with the D-strings of type II string theory. In this picture the Higgs field represents the open string tachyon of the D-D pair and the axion is dual to a Ramond-Ramond form. The crucial term allowing the existence of nonsingular BPS strings is the Fayet-Iliopoulos term, which is related to the tensions of the D-string and of the parent branes. Despite the presence of the axion, the strings are BPS and carry finite energy, due to the fact that the space gets very slowly decompactified away from the core, screening the long range axion field (or equivalently the theory approaches an infinitely weak 4D coupling). Within our 4D effective action we also identify another class of BPS string solutions (s-strings) which have no ten-dimensional analog, and can only exist after compactification.

  16. Selenium impacts on razorback sucker, Colorado River, Colorado I. Adults.

    PubMed

    Hamilton, Steven J; Holley, Kathy M; Buhl, Kevin J; Bullard, Fern A; Ken Weston, L; McDonald, Susan F

    2005-05-01

    Adult razorback sucker (Xyrauchen texanus) were exposed to various selenium concentrations in ponds and isolated river channels of the Colorado River near Grand Junction, CO, to determine effects on their growth and residue accumulation over an 11-month period. Adults at Horsethief ponds were fed a commercial diet, whereas fish at Adobe Creek channel and North Pond foraged on natural food items. Selenium concentrations at Horsethief were 2.2 microg/L in water, 0.1-1.4 microg/g in sediment, and 2.3-3.1 microg/g in food organisms (1.1 microg/g in commercial fish food), at Adobe Creek were 3.8 microg/L in water, 0.5-2.1 microg/g in sediment, and 4-56 microg/g in food organisms, and at North Pond were 9.5 microg/L in water, 7-55 microg/g in sediment, and 20-81 microg/g in food organisms. The selenium concentrations in muscle plugs from adults at Adobe Creek (11.7 microg/g, SD = 0.4, n = 6) and North Pond (16.6 microg/g, SD = 1.0, n = 6) were greater than at Horsethief (4.5 microg/g, SD = 0.2, n = 6). During a depuration period adults from Adobe Creek and North Pond lost 1-2% of their selenium burden in 32 days and 14-19% in 66 days. Selenium accumulated in razorback sucker above toxic thresholds reported in other studies, yet those residues were less than those reported in muscle plugs of 40% of wild razorback sucker caught in the Green River, Utah.

  17. Selenium impacts on razorback sucker, Colorado River, Colorado: I. Adults

    USGS Publications Warehouse

    Hamilton, S.J.; Holley, K.M.; Buhl, K.J.; Bullard, F.A.; Weston, L.K.; McDonald, S.F.

    2005-01-01

    Adult razorback sucker (Xyrauchen texanus) were exposed to various selenium concentrations in ponds and isolated river channels of the Colorado River near Grand Junction, CO, to determine effects on their growth and residue accumulation over an 11-month period. Adults at Horsethief ponds were fed a commercial diet, whereas fish at Adobe Creek channel and North Pond foraged on natural food items. Selenium concentrations at Horsethief were 2.2 ??g/L in water, 0.1-1.4 ??g/g in sediment, and 2.3-3.1 ??g/g in food organisms (1.1 ??g/g in commercial fish food), at Adobe Creek were 3.8 ??g/L in water, 0.5-2.1 ??g/g in sediment, and 4-56 ??g/g in food organisms, and at North Pond were 9.5 ??g/L in water, 7-55 ??g/g in sediment, and 20-81 ??g/g in food organisms. The selenium concentrations in muscle plugs from adults at Adobe Creek (11.7 ??g/g, SD=0.4, n=6) and North Pond (16.6 ??g/g, SD=1.0, n=6) were greater than at Horsethief (4.5 ??g/g, SD=0.2, n=6). During a depuration period adults from Adobe Creek and North Pond lost 1-2% of their selenium burden in 32 days and 14-19% in 66 days. Selenium accumulated in razorback sucker above toxic thresholds reported in other studies, yet those residues were less than those reported in muscle plugs of 40% of wild razorback sucker caught in the Green River, Utah.

  18. Why rods and cones?

    PubMed

    Lamb, T D

    2016-02-01

    Under twenty-first-century metropolitan conditions, almost all of our vision is mediated by cones and the photopic system, yet cones make up barely 5% of our retinal photoreceptors. This paper looks at reasons why we additionally possess rods and a scotopic system, and asks why rods comprise 95% of our retinal photoreceptors. It considers the ability of rods to reliably signal the arrival of individual photons of light, as well as the ability of the retina to process these single-photon signals, and it discusses the advantages that accrue. Drawbacks in the arrangement, including the very slow dark adaptation of scotopic vision, are also considered. Finally, the timing of the evolution of cone and rod photoreceptors, the retina, and the camera-style eye is summarised.

  19. String Cosmology: A Review

    SciTech Connect

    McAllister, Liam P.; Silverstein, Eva

    2007-10-22

    We give an overview of the status of string cosmology. We explain the motivation for the subject, outline the main problems, and assess some of the proposed solutions. Our focus is on those aspects of cosmology that benefit from the structure of an ultraviolet-complete theory.

  20. Experimenting with Guitar Strings

    NASA Astrophysics Data System (ADS)

    LoPresto, Michael C.

    2006-11-01

    What follows is a description of a simple experiment developed in a nonmathematical general education science course on sound and light for fine arts students in which a guitar is used with data collection hardware and software to verify the properties of standing waves on a string.

  1. Experimenting with Guitar Strings

    ERIC Educational Resources Information Center

    LoPresto, Michael C.

    2006-01-01

    What follows is a description of a simple experiment developed in a non-mathematical general education science course on sound and light for fine arts students in which a guitar is used with data collection hardware and software to verify the properties of standing waves on a string.

  2. Exotic nonrelativistic string

    SciTech Connect

    Casalbuoni, Roberto; Gomis, Joaquim; Longhi, Giorgio

    2007-12-15

    We construct a classical nonrelativistic string model in 3+1 dimensions. The model contains a spurion tensor field that is responsible for the noncommutative structure of the model. Under double-dimensional reduction the model reduces to the exotic nonrelativistic particle in 2+1 dimensions.

  3. A Vibrating String Experiment

    ERIC Educational Resources Information Center

    Tsutsumanova, Gichka; Russev, Stoyan

    2013-01-01

    A simple experiment demonstrating the excitation of a standing wave in a metal string is presented here. Several tasks using the set-up are considered, which help the students to better understand the standing waves, the interaction between electric current and magnetic field and the resonance phenomena. This can serve also as a good lecture…

  4. Strings in four dimensions

    SciTech Connect

    Bachas, C.P.

    1988-01-01

    We review the construction and properties of four dimensional string models, using free fermions on the world-sheet. We prove that as opposed to gauge symmetries, broken space-time supersymmetry can only be restored continuously by decompactification. 40 refs.

  5. Gravity and Strings

    NASA Astrophysics Data System (ADS)

    Ortín, Tomás

    2015-03-01

    1. Differential geometry; 2. Symmetries and Noether's theorems; 3. A perturbative introduction to general relativity; 4. Action principles for gravity; 5. Pure N=1,2,d=4 supergravities; 6. Matter-coupled N=1,d=4 supergravity; 7. Matter-coupled N=2,d=4 supergravity; 8. A generic description of all the N>2,d=4 SUEGRAS; 9. Matter-coupled N=1,d=5 supergravity; 10. Conserved charges in general relativity; 11. The Schwarzschild black hole; 12. The Reissner-Nordström black hole; 13. The Taub-NUT solution; 14. Gravitational pp-waves; 15. The Kaluza-Klein black hole; 16. Dilaton and dilaton/axion black holes; 17. Unbroken supersymmetry I: supersymmetric vacua; 18. Unbroken supersymmetry II: partially supersymmetric solutions; 19. Supersymmetric black holes from supergravity; 20. String theory; 21. The string effective action and T duality; 22. From eleven to four dimensions; 23. The type-IIB superstring and type-II T duality; 24. Extended objects; 25. The extended objects of string theory; 26. String black holes in four and five dimensions; 27. The FGK formalism for (single, static) black holes and branes; Appendices: A.1 Lie groups, symmetric spaces, and Yang-Mills fields; A.2 The irreducible, non-symmetric Riemannian spaces of special holonomy; A.3 Miscellanea on the symplectic group; A.4 Gamma matrices and spinors; A.5 Kähler geometry; A.6 Special Kähler geometry; A.7 Quaternionic-Kähler geometry.

  6. Evolution of cosmic string networks

    NASA Technical Reports Server (NTRS)

    Albrecht, Andreas; Turok, Neil

    1989-01-01

    A discussion of the evolution and observable consequences of a network of cosmic strings is given. A simple model for the evolution of the string network is presented, and related to the statistical mechanics of string networks. The model predicts the long string density throughout the history of the universe from a single parameter, which researchers calculate in radiation era simulations. The statistical mechanics arguments indicate a particular thermal form for the spectrum of loops chopped off the network. Detailed numerical simulations of string networks in expanding backgrounds are performed to test the model. Consequences for large scale structure, the microwave and gravity wave backgrounds, nucleosynthesis and gravitational lensing are calculated.

  7. Current balancing for battery strings

    DOEpatents

    Galloway, James H.

    1985-01-01

    A battery plant is described which features magnetic circuit means for balancing the electrical current flow through a pluraliircuitbattery strings which are connected electrically in parallel. The magnetic circuit means is associated with the battery strings such that the conductors carrying the electrical current flow through each of the battery strings pass through the magnetic circuit means in directions which cause the electromagnetic fields of at least one predetermined pair of the conductors to oppose each other. In an alternative embodiment, a low voltage converter is associated with each of the battery strings for balancing the electrical current flow through the battery strings.

  8. String theories and millisecond pulsars

    NASA Astrophysics Data System (ADS)

    Sanchez, N.; Signore, M.

    1988-11-01

    We discuss the two ways of connecting string theories (cosmic, fundamental and the connection between them) to the observational reality: (i) radioastronomy observations (millisecond pulsar timing), and (ii) elementary particle phenomenology (compactification schemes). We study the limits imposed on the string parameter Gμ by recent millisecond pulsar timings. Cosmic strings derived from GUTs agree with (i). For cosmic strings derived from fundamental strings themselves there is contradiction between (i) and (ii). One of these scenarios connecting string theory to reality must be revised (or the transition from fundamental into cosmic strings rejected). Meanwhile, millisecond pulsar can select one scenario, or reject both of them. UA 336 Laboratoire Associé au CNRS, Observatoire de Meudon et Ecole Normale Supérieure, 24 rue Lhomond, F-75231 Paris Cedex 05, France.

  9. Device for balancing parallel strings

    DOEpatents

    Mashikian, Matthew S.

    1985-01-01

    A battery plant is described which features magnetic circuit means in association with each of the battery strings in the battery plant for balancing the electrical current flow through the battery strings by equalizing the voltage across each of the battery strings. Each of the magnetic circuit means generally comprises means for sensing the electrical current flow through one of the battery strings, and a saturable reactor having a main winding connected electrically in series with the battery string, a bias winding connected to a source of alternating current and a control winding connected to a variable source of direct current controlled by the sensing means. Each of the battery strings is formed by a plurality of batteries connected electrically in series, and these battery strings are connected electrically in parallel across common bus conductors.

  10. Polished rod liner puller assmbly

    SciTech Connect

    Baxter, B.V.

    1990-01-02

    This patent describes a polished rod liner puller assembly operable with a well casing head assembly to remove a polished rod liner member of a polished rod liner assembly from a well. It comprises: a work table assembly operable to be placed around the well casing head assembly and enclose the polished rod liner assembly; a base plate assembly mounted on the work table assembly; a piston and cylinder jack assembly mounted on the base plate assembly and extended upwardly therefrom; and a winged rod clamp assembly connectable to the piston and cylinder jack assembly and to a polished rod member of the polished rod liner assembly and operable on actuation of the piston and cylinder jack assembly to axially move the polished rod member and the polished rod liner member to remove the polished rod liner member from the well.

  11. Nonlinearity and noise at the rod - rod bipolar cell synapse

    PubMed Central

    Trexler, E. Brady; Casti, Alexander R.R.; Zhang, Yu

    2010-01-01

    In the retina, rod bipolar (RBP) cells synapse with many rods, and suppression of rod outer segment and synaptic noise is necessary for their detection of rod single photon responses (SPRs). Depending on the rods’ signal to noise ratio (SNR), the suppression mechanism will likely eliminate some SPRs as well, resulting in decreased quantum efficiency. We examined this synapse in rabbit, where 100 rods converge onto each RBP. Suction electrode recordings showed that rabbit rod SPRs were difficult to distinguish from noise (independent SNR estimates were 2.3 and 2.8). Nonlinear transmission from rods to RBPs improved response detection (SNR = 8.7), but a large portion of the rod SPRs were discarded. For the dimmest flashes, the loss approached 90%. Despite the high rejection ratio, noise of two distinct types were apparent in the RBP traces: low amplitude rumblings and discrete events that resembled the SPR. The SPR-like event frequency suggests they result from thermal isomerizations of rhodopsin, which occured at the rate 0.033 s−1rod−1. The presence of low amplitude noise is explained by a sigmoidal input-output relationship at the rod - RBP synapse and the input of noisy rods. The rabbit rod SNR and RBP quantum efficiency are the lowest yet reported, suggesting that the quantum efficiency of the rod - RBP synapse may depend on the SNR in rods. These results point to the possibility that fewer photoisomerizations are discarded for species such as primate, which has a higher rod SNR. PMID:21047445

  12. Postmodern string theory: Stochastic formulation

    NASA Astrophysics Data System (ADS)

    Aurilia, A.; Spallucci, E.; Vanzetta, I.

    1994-11-01

    In this paper we study the dynamics of a statistical ensemble of strings, building on a recently proposed gauge theory of the string geodesic field. We show that this stochastic approach is equivalent to the Carathéodory formulation of the Nambu-Goto action, supplemented by an averaging procedure over the family of classical string world sheets which are solutions of the equation of motion. In this new framework, the string geodesic field is reinterpreted as the Gibbs current density associated with the string statistical ensemble. Next, we show that the classical field equations derived from the string gauge action can be obtained as the semiclassical limit of the string functional wave equation. For closed strings, the wave equation itself is completely analogous to the Wheeler-DeWitt equation used in quantum cosmology. Thus, in the string case, the wave function has support on the space of all possible spatial loop configurations. Finally, we show that the string distribution induces a multiphase, or cellular structure on the spacetime manifold characterized by domains with a purely Riemannian geometry separated by domain walls over which there exists a predominantly Weyl geometry.

  13. Understanding flame rods

    SciTech Connect

    McAuley, J.A. Jr.

    1995-11-01

    The flame rod is probably the least understood method of flame detection. Although it is not recommended for oilfired equipment, it is very common on atmospheric, or {open_quotes}in-shot,{close_quotes} gas burners. It is also possible, although not common, to have an application with a constant gas pilot, monitored by a flame rod, and maintaining an oil main flame. Regardless of the application, chances are that flame rods will be encountered during the course of servicing. The technician today must be versatile and able to work on many different types of equipment. One must understand the basic principles of flame rods, and how to correct potential problems. The purpose of a flame detection system is two-fold: (1) to prove there is no flame when there shouldn`t be one, and (2) to prove there is a flame when there should be one. Flame failure response time is very important. This is the amount of time it takes to realize there is a loss of flame, two to four seconds is typical today. Prior to flame rods, either bi-metal or thermocouple type flame detectors were common. The response time for these detectors was up to three minutes, seldom less than one minute.

  14. Axions in String Theory

    SciTech Connect

    Svrcek, Peter; Witten, Edward; /Princeton, Inst. Advanced Study

    2006-06-09

    In the context of string theory, axions appear to provide the most plausible solution of the strong CP problem. However, as has been known for a long time, in many string-based models, the axion coupling parameter Fa is several orders of magnitude higher than the standard cosmological bounds. We re-examine this problem in a variety of models, showing that Fa is close to the GUT scale or above in many models that have GUT-like phenomenology, as well as some that do not. On the other hand, in some models with Standard Model gauge fields supported on vanishing cycles, it is possible for Fa to be well below the GUT scale.

  15. Wing on a String

    ERIC Educational Resources Information Center

    Fitzgerald, Mike; Brand, Lance

    2004-01-01

    In this article, the authors present an activity that shows students how flight occurs. The "wing on a string" is a simple teacher-made frame that consists of PVC pipe, fishing line, and rubber bands--all readily available hardware store items. The only other materials/tools involved are a sheet of paper, some pieces of a soda straw, a stapler,…

  16. Anyons from Strings

    SciTech Connect

    Mezincescu, Luca; Townsend, Paul K.

    2010-11-05

    The Nambu-Goto string in a three-dimensional (3D) Minkowski spacetime is quantized preserving Lorentz invariance and parity. The spectrum of massive states contains anyons. An ambiguity in the ground state energy is resolved by the 3D N=1 Green-Schwarz superstring, which has massless ground states describing a dilaton and dilatino, and first-excited states of spin 1/4.

  17. Demographics and 2008 Run Timing of Adult Lost River (Deltistes luxatus) and Shortnose (Chasmistes brevirostris) Suckers in Upper Klamath Lake

    USGS Publications Warehouse

    Janney, Eric C.; Hayes, Brian S.; Hewitt, David A.; Barry, Patrick M.; Scott, Alta; Koller, Justin; Johnson, Mark; Blackwood, Greta

    2009-01-01

    We used capture-recapture data to assess population dynamics of endangered Lost River suckers (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) in Upper Klamath Lake, Oregon. The Cormack-Jolly-Seber method was used to estimate apparent survival probabilities, and a temporal symmetry model was used to estimate annual seniority probabilities. Information theoretic modeling was used to assess variation in parameter estimates due to time, gender, and species. In addition, length data were used to detect multiple year-class failures and events of high recruitment into adult spawning populations. Survival of adult Lost River and shortnose suckers varied substantially across years. Relatively high annual mortality was observed for the lakeshore-spawning Lost River sucker subpopulation in 2002 and for the river spawning subpopulation in 2001. Shortnose suckers experienced high mortality in 2001 and 2004. This indicates that high mortality events are not only species specific, but also are specific to subpopulations for Lost River suckers. Seniority probability estimates and length composition data indicate that recruitment of new individuals into adult sucker populations has been sparse. The overall fitness of Upper Klamath Lake sucker populations are of concern given the low observed survival in some years and the paucity of recent recruitment. During most years, estimates of survival probabilities were lower than seniority probabilities, indicating net losses in adult sucker population abundances. The evidence for decline was more marked for shortnose suckers than for Lost River suckers. Our data indicated that sucker survival for both species, but especially shortnose suckers, was sometimes low in years without any observed fish kills. This indicates that high mortality can occur over a protracted period, resulting in poor annual survival, but will not necessarily be observed in association with a fish kill. A better understanding of the factors

  18. Down hole shock absorber

    SciTech Connect

    Coston, H.A.

    1990-03-05

    This patent describes a well pump system. It comprises: a sucker rod string; a pump reciprocable in response to the string; a cylinder; a piston disposed for vertical reciprocal motion within the cylinder; means for biasing the cylinder and the piston against compressive motion; means for pneumatically relieving pressure in the cylinder during compressive motion; and means for preventing relative rotational motion and for limiting relative expansive motion between the cylinder and the piston; the cylinder and the piston being coaxially mounted in the sucker rod string proximate and above the pump to buffer forces transmitted through the string.

  19. Quantized string models

    NASA Astrophysics Data System (ADS)

    Fradkin, E. S.; Tseytlin, A. A.

    1982-10-01

    We discuss and compare the Lorentz covariant path integral quantization of the three bose string models, namely, the Nambu, Eguchi and Brink-Di Vecchia-Howe-Polyakov (BDHP) ones. Along with a critical review of the subject with some uncertainties and ambiguities clearly stated, various new results are presented. We work out the form of the BDHP string ansatz for the Wilson average and prove a formal inequivalence of the exact Nambu and BDHP models for any space-time dimension d. The above three models, known to be equivalent on the classical level, are shown to be equivalent in a semiclassical approximation near a minimal surface and also in the leading 1/d- approximation for the static overlineqq-potential. We analyse scattering amplitudes predicted by the BDHP string and find that when exactly calculated for d < 26 they are different from the old dual ones, and possess a non-linear spectrum which may be considered as free from tachyons in the ground state.

  20. The String of Pearls

    2006-07-01

    A team of collaborators within the Southwest Regional Partnership (SRP) on Carbon Sequestration developed an interactive software tool to help facilitate discussions involving the science, engineering, economic and policy considerations for a carbon sequestration pilot project. This model illustrates the "String of Pearls" algorithm used to develop a hypothetical carbon dioxide (CO2) transportation network in sequence with existing infrastructure. The "String of Pearls" model can assess geological sink combinations according to their distance from themore » point source (e.g., power plant), relative size (to maintain a useful fill lifetime for a project), relative distance from existing CO2 transportation infrastructure, and other salient project attributes. The results indicate that the cost to capture CO2 at point sources (e.g. power plants) is the largest component of the overall CO2 capture, transportation and storage system's initial cost estimate. The "String of Pearls" Integrated Assessment model can help planners assess these issues using an integrated, systems view when deciding where to develop future carbon sequestration pilot projects. Likely users of this model include partners within the SRP, other regional partnerships and interested individuals, and private industry interested in carbon sequestration systems. The model seeks to improve understanding of the economic viability and emission trade-offs associated with all stages of carbone sequestration systems analysis.« less

  1. The String of Pearls

    SciTech Connect

    Borns, David J.; Kobos, Peter H.; Malczynski, Leonard A.

    2006-07-01

    A team of collaborators within the Southwest Regional Partnership (SRP) on Carbon Sequestration developed an interactive software tool to help facilitate discussions involving the science, engineering, economic and policy considerations for a carbon sequestration pilot project. This model illustrates the "String of Pearls" algorithm used to develop a hypothetical carbon dioxide (CO2) transportation network in sequence with existing infrastructure. The "String of Pearls" model can assess geological sink combinations according to their distance from the point source (e.g., power plant), relative size (to maintain a useful fill lifetime for a project), relative distance from existing CO2 transportation infrastructure, and other salient project attributes. The results indicate that the cost to capture CO2 at point sources (e.g. power plants) is the largest component of the overall CO2 capture, transportation and storage system's initial cost estimate. The "String of Pearls" Integrated Assessment model can help planners assess these issues using an integrated, systems view when deciding where to develop future carbon sequestration pilot projects. Likely users of this model include partners within the SRP, other regional partnerships and interested individuals, and private industry interested in carbon sequestration systems. The model seeks to improve understanding of the economic viability and emission trade-offs associated with all stages of carbone sequestration systems analysis.

  2. Coulomb string tension, asymptotic string tension, and the gluon chain

    DOE PAGES

    Greensite, Jeff; Szczepaniak, Adam P.

    2015-02-01

    We compute, via numerical simulations, the non-perturbative Coulomb potential and position-space ghost propagator in pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

  3. Effects of anisotropic dynamics on cosmic strings

    SciTech Connect

    Kunze, Kerstin E.

    2011-08-01

    The dynamics of cosmic strings is considered in anisotropic backgrounds. In particular, the behaviour of infinitely long straight cosmic strings and of cosmic string loops is determined. Small perturbations of a straight cosmic string are calculated. The relevance of these results is discussed with respect to the possible observational imprints of an anisotropic phase on the behaviour of a cosmic string network.

  4. Factorization of chiral string amplitudes

    NASA Astrophysics Data System (ADS)

    Huang, Yu-tin; Siegel, Warren; Yuan, Ellis Ye

    2016-09-01

    We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: as found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to be auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.

  5. String fluid in local equilibrium

    NASA Astrophysics Data System (ADS)

    Schubring, Daniel; Vanchurin, Vitaly

    2014-10-01

    We study the solutions of string fluid equations under the assumption of a local equilibrium which was previously obtained in the context of the kinetic theory. We show that the fluid can be foliated into noninteracting submanifolds whose equations of motion are exactly that of the wiggly strings considered previously by Vilenkin and Carter. In a special case of negligible statistical variance in either the left- or the right-moving directions of microscopic strings, the submanifolds are described by the action of a null-current-carrying chiral string. When both variances vanish the submanifolds are described by the Nambu-Goto action and the string fluid reduces to the string dust introduced by Stachel.

  6. COMPOSITE CONTROL ROD

    DOEpatents

    Rock, H.R.

    1963-12-24

    A composite control rod for use in controlling a nuclear reactor is described. The control rod is of sandwich construction in which finned dowel pins are utilized to hold together sheets of the neutron absorbing material and nonabsorbing structural material thereby eliminating the need for being dependent on the absorbing material for structural support. The dowel pins perform the function of absorbing the forces due to differential thermal expansion, seating further with the fins into the sheets of material and crushing before damage is done either to the absorbing or non-absorbing material. (AEC)

  7. Experimenting with string musical instruments

    NASA Astrophysics Data System (ADS)

    LoPresto, Michael C.

    2012-03-01

    What follows are several investigations involving string musical instruments developed for and used in a Science of Sound & Light course. The experiments make use of a guitar, orchestral string instruments and data collection and graphing software. They are designed to provide students with concrete examples of how mathematical formulae, when used in physics, represent reality that can actually be observed, in this case, the operation of string musical instruments.

  8. Classical theory of radiating strings

    NASA Technical Reports Server (NTRS)

    Copeland, Edmund J.; Haws, D.; Hindmarsh, M.

    1990-01-01

    The divergent part of the self force of a radiating string coupled to gravity, an antisymmetric tensor and a dilaton in four dimensions are calculated to first order in classical perturbation theory. While this divergence can be absorbed into a renormalization of the string tension, demanding that both it and the divergence in the energy momentum tensor vanish forces the string to have the couplings of compactified N = 1 D = 10 supergravity. In effect, supersymmetry cures the classical infinities.

  9. Cosmic string induced CMB maps

    SciTech Connect

    Landriau, M.; Shellard, E. P. S.

    2011-02-15

    We compute maps of CMB temperature fluctuations seeded by cosmic strings using high resolution simulations of cosmic strings in a Friedmann-Robertson-Walker universe. We create full-sky, 18 deg. and 3 deg. CMB maps, including the relevant string contribution at each resolution from before recombination to today. We extract the angular power spectrum from these maps, demonstrating the importance of recombination effects. We briefly discuss the probability density function of the pixel temperatures, their skewness, and kurtosis.

  10. CHANGES IN GENETIC DIVERSITY OF A WHITE SUCKER POPULATION FOLLOWING EXPERIMENTAL WHOLE-LAKE ACIDIFICATION

    EPA Science Inventory

    Despite great strides to reduce sulfur dioxide emissions over the last decade, acid precipitation remains a persistent threat to North American fish communities. A demographic analysis of white suckers in an experimentally acidified oligotrophic lake in northwest Ontario demonst...

  11. [The oral sucker muscles of six representatives of the order Paramphistomatida (Plathelminthes, Trematoda)].

    PubMed

    Burdakova, E N; Yastrebova, I V; Yastrebov, M V

    2015-01-01

    The spatial arrangement of muscles in the oral suckers of six trematode species belonging to five families of the order Paramphistomatida is described. The functional load and adaptive significance of different muscle groups in the suckers themselves and the associated structures--preoral lip and muscular cap--are discussed. Complete section series in three projections have been examined; this demonstrates the presence of previously unnoticed structures, namely, semicircular and diagonal muscles, regulating shape of the oral cavity, and short longitudinal muscles, acting as a sphincter, as well as localization of the largest internal muscles on the sucker lateral sides. It has been shown that the presence of internal longitudinal muscles suggests that the organs in question are closer to the oral suckers of other trematodes rather than to their pharynxes.

  12. Benzo[a]pyrene metabolism and excretion in white suckers with chronic liver diseases

    SciTech Connect

    Smith, I.R.; Kirby, G.M.; Ferguson, H.W.; Hayes, M.A. )

    1993-05-01

    Wild white suckers (Catostomus commersoni) with diseased bile ducts excreted an oral dose of benzo[a]pyrene (BaP) into their bile as glucuronide, glutathione, and sulfo-conjugates at twice the rate of an unaffected reference population. BaP-hydroxylase (10% higher in the diseased population), glutathione-S-transferase (similar), or uridine-5[prime]-diphosphoglucuronic acid transferase (50% lower) levels did not correlate with these excretion rates. Metabolite levels were 57% higher in the liver of affected suckers than those in the liver of reference suckers, which might be due to bile retention within the diseased bile ducts. The bile duct disease affecting white suckers does not appear to restrict the metabolism and excretion of BaP.

  13. Non-supersymmetric string theory

    NASA Astrophysics Data System (ADS)

    Martinec, Emil J.; Robbins, Daniel; Sethi, Savdeep

    2011-10-01

    A class of non-supersymmetric string backgrounds can be constructed using twists that involve space-time fermion parity. We propose a non-perturbative definition of string theory in these backgrounds via gauge theories with supersymmetry softly broken by twisted boundary conditions. The perturbative string spectrum is reproduced, and qualitative effects of the interactions are discussed. Along the way, we find an interesting mechanism for inflation. The end state of closed string tachyon condensation is a highly excited state in the gauge theory which, in all likelihood, does not have a geometric interpretation.

  14. Evolution of cosmic string networks

    NASA Technical Reports Server (NTRS)

    Albrecht, Andreas; Turok, Neil

    1989-01-01

    Results on cosmic strings are summarized including: (1) the application of non-equilibrium statistical mechanics to cosmic string evolution; (2) a simple one scale model for the long strings which has a great deal of predictive power; (3) results from large scale numerical simulations; and (4) a discussion of the observational consequences of our results. An upper bound on G mu of approximately 10(-7) emerges from the millisecond pulsar gravity wave bound. How numerical uncertainties affect this are discussed. Any changes which weaken the bound would probably also give the long strings the dominant role in producing observational consequences.

  15. Evolution of cosmic string networks

    SciTech Connect

    Albrecht, A.; Turok, N.

    1989-06-01

    We summarize our new results on cosmic strings. These results include: the application of non-equilibrium statistical mechanics to cosmic string evolution, a simple ''one scale'' model for the long strings which has a great deal of predictive power, results from large scale numerical simulations, and a discussion of the observational consequences of our results. An upper bond on G/mu/ of approximately 10/sup /minus/7/ emerges from the millisecond pulsar gravity wave bound. We discuss how numerical uncertainties affect this. Any changes which weaken the bound would probably also give the long strings the dominant role in producing observational consequences. 22 refs.

  16. Cosmic sparks from superconducting strings.

    PubMed

    Vachaspati, Tanmay

    2008-10-01

    We investigate cosmic sparks from cusps on superconducting cosmic strings in light of the recently discovered millisecond radio burst by Lorimer et al.. We find that the observed duration, fluence, spectrum, and event rate can be reasonably explained by grand unification scale superconducting cosmic strings that carry currents approximately 10{5} GeV. The superconducting string model predicts an event rate that falls off only as S{-1/2}, where S is the energy flux, and hence predicts a population of very bright bursts. Other surveys, with different observational parameters, are shown to impose tight constraints on the superconducting string model. PMID:18851517

  17. Cosmic Sparks from Superconducting Strings

    SciTech Connect

    Vachaspati, Tanmay

    2008-10-03

    We investigate cosmic sparks from cusps on superconducting cosmic strings in light of the recently discovered millisecond radio burst by Lorimer et al.. We find that the observed duration, fluence, spectrum, and event rate can be reasonably explained by grand unification scale superconducting cosmic strings that carry currents {approx}10{sup 5} GeV. The superconducting string model predicts an event rate that falls off only as S{sup -1/2}, where S is the energy flux, and hence predicts a population of very bright bursts. Other surveys, with different observational parameters, are shown to impose tight constraints on the superconducting string model.

  18. Musculoskeletal determinants of pelvic sucker function in Hawaiian stream gobiid fishes: interspecific comparisons and allometric scaling.

    PubMed

    Maie, Takashi; Schoenfuss, Heiko L; Blob, Richard W

    2013-07-01

    Gobiid fishes possess a distinctive ventral sucker, formed from fusion of the pelvic fins. This sucker is used to adhere to a wide range of substrates including, in some species, the vertical cliffs of waterfalls that are climbed during upstream migrations. Previous studies of waterfall-climbing goby species have found that pressure differentials and adhesive forces generated by the sucker increase with positive allometry as fish grow in size, despite isometry or negative allometry of sucker area. To produce such scaling patterns for pressure differential and adhesive force, waterfall-climbing gobies might exhibit allometry for other muscular or skeletal components of the pelvic sucker that contribute to its adhesive function. In this study, we used anatomical dissections and modeling to evaluate the potential for allometric growth in the cross-sectional area, effective mechanical advantage (EMA), and force generating capacity of major protractor and retractor muscles of the pelvic sucker (m. protractor ischii and m. retractor ischii) that help to expand the sealed volume of the sucker to produce pressure differentials and adhesive force. We compared patterns for three Hawaiian gobiid species: a nonclimber (Stenogobius hawaiiensis), an ontogenetically limited climber (Awaous guamensis), and a proficient climber (Sicyopterus stimpsoni). Scaling patterns were relatively similar for all three species, typically exhibiting isometric or negatively allometric scaling for the muscles and lever systems examined. Although these scaling patterns do not help to explain the positive allometry of pressure differentials and adhesive force as climbing gobies grow, the best climber among the species we compared, S. stimpsoni, does exhibit the highest calculated estimates of EMA, muscular input force, and output force for pelvic sucker retraction at any body size, potentially facilitating its adhesive ability. PMID:23450656

  19. Musculoskeletal determinants of pelvic sucker function in Hawaiian stream gobiid fishes: interspecific comparisons and allometric scaling.

    PubMed

    Maie, Takashi; Schoenfuss, Heiko L; Blob, Richard W

    2013-07-01

    Gobiid fishes possess a distinctive ventral sucker, formed from fusion of the pelvic fins. This sucker is used to adhere to a wide range of substrates including, in some species, the vertical cliffs of waterfalls that are climbed during upstream migrations. Previous studies of waterfall-climbing goby species have found that pressure differentials and adhesive forces generated by the sucker increase with positive allometry as fish grow in size, despite isometry or negative allometry of sucker area. To produce such scaling patterns for pressure differential and adhesive force, waterfall-climbing gobies might exhibit allometry for other muscular or skeletal components of the pelvic sucker that contribute to its adhesive function. In this study, we used anatomical dissections and modeling to evaluate the potential for allometric growth in the cross-sectional area, effective mechanical advantage (EMA), and force generating capacity of major protractor and retractor muscles of the pelvic sucker (m. protractor ischii and m. retractor ischii) that help to expand the sealed volume of the sucker to produce pressure differentials and adhesive force. We compared patterns for three Hawaiian gobiid species: a nonclimber (Stenogobius hawaiiensis), an ontogenetically limited climber (Awaous guamensis), and a proficient climber (Sicyopterus stimpsoni). Scaling patterns were relatively similar for all three species, typically exhibiting isometric or negatively allometric scaling for the muscles and lever systems examined. Although these scaling patterns do not help to explain the positive allometry of pressure differentials and adhesive force as climbing gobies grow, the best climber among the species we compared, S. stimpsoni, does exhibit the highest calculated estimates of EMA, muscular input force, and output force for pelvic sucker retraction at any body size, potentially facilitating its adhesive ability.

  20. Inspiration, simulation and design for smart robot manipulators from the sucker actuation mechanism of cephalopods.

    PubMed

    Grasso, Frank W; Setlur, Pradeep

    2007-12-01

    Octopus arms house 200-300 independently controlled suckers that can alternately afford an octopus fine manipulation of small objects and produce high adhesion forces on virtually any non-porous surface. Octopuses use their suckers to grasp, rotate and reposition soft objects (e.g., octopus eggs) without damaging them and to provide strong, reversible adhesion forces to anchor the octopus to hard substrates (e.g., rock) during wave surge. The biological 'design' of the sucker system is understood to be divided anatomically into three functional groups: the infundibulum that produces a surface seal that conforms to arbitrary surface geometry; the acetabulum that generates negative pressures for adhesion; and the extrinsic muscles that allow adhered surfaces to be rotated relative to the arm. The effector underlying these abilities is the muscular hydrostat. Guided by sensory input, the thousands of muscle fibers within the muscular hydrostats of the sucker act in coordination to provide stiffness or force when and where needed. The mechanical malleability of octopus suckers, the interdigitated arrangement of their muscle fibers and the flexible interconnections of its parts make direct studies of their control challenging. We developed a dynamic simulator (ABSAMS) that models the general functioning of muscular hydrostat systems built from assemblies of biologically constrained muscular hydrostat models. We report here on simulation studies of octopus-inspired and artificial suckers implemented in this system. These simulations reproduce aspects of octopus sucker performance and squid tentacle extension. Simulations run with these models using parameters from man-made actuators and materials can serve as tools for designing soft robotic implementations of man-made artificial suckers and soft manipulators.

  1. Transfer of Strings to the Module Fixture

    NASA Technical Reports Server (NTRS)

    Frasch, W.

    1982-01-01

    Work station for transferring entire strings of solar cells places successive strings alined, with offset, or reversed end for end. Thus, various solar module formats can be accommodated. Two vacuum cups hold each solar cell in string being transferred.

  2. Experimental Investigation on the Morphology and Adhesion Mechanism of Leech Posterior Suckers

    PubMed Central

    Dong, Wenhao

    2015-01-01

    The posterior sucker of a leech represents a fascinating natural system that allows the leech to adhere to different terrains and substrates. However, the mechanism of adhesion and desorption has not yet to be elucidated. In order to better understand how the adhesion is performed, we analyzed the surface structure, adsorption movements, the muscles’ distribution, physical characteristics, and the adsorption force of the leech posterior suckers by experimental investigation. Three conclusions can be drawn based on the obtained experimental results. First, the adhesion by the posterior sucker is wet adhesion, because the surface of the posterior sucker is smooth and the sealing can only be achieved on wet surfaces. Second, the deformation texture, consisting of soft collagen tissues and highly ductile epidermal tissues, plays a key role in adhering to rough surfaces. Finally, the adhesion and desorption is achieved by the synergetic operation of six muscle fibers working in different directions. Concrete saying, directional deformation of the collagen/epithermal interface driven by spatially-distributed muscle fibers facilitates the excretion of fluids in the sucker venter, thus allowing liquid sealing. Furthermore, we found that the adhesion strength is directly related to the size of the contact surface which is generated and affected by the sucker deformation. Such an underlying physical mechanism offers potential cues for developing innovative bio-inspired artificial adhesion systems. PMID:26536352

  3. Effect of suspended sediment on vulnerability of young razorback suckers to predation

    USGS Publications Warehouse

    Johnson, J.E.; Hines, R.T.

    1999-01-01

    The decline of native fishes in North America is principally a result of altered habitats, and the impact of mainstream dams has accounted for many of the habitat changes. Diminished turbidity, and introduced nonnative predators were investigated as possible reasons for the decline of endangered razorback suckers Xyrauchen texanus in the Colorado River. In laboratory tests, young razorback suckers selected clear water over two water samples with higher concentrations of suspended sediment. In clear water, however, young razorback suckers were extremely susceptible to predation; native Colorado squawfish Ptychocheilus lucius consumed 90% of test razorback suckers, and nonnative green sunfish Lepomis cyanellus consumed 99.6%. As turbidity increased, razorback sucker predator avoidance improved and differences in predator success disappeared. Winter-spring spawning by razorback suckers in Lake Mohave, along with the extreme susceptibility of larvae to predation in clear water, may account for total recruitment failure in that lake. However, in upper basin rivers, suspended sediments remain high enough to limit predation by fishes tested, suggesting that other impacts, including contaminants and lack of floodplain habitat, may be thwarting recruitment in those rivers.

  4. M-strings, monopole strings, and modular forms

    NASA Astrophysics Data System (ADS)

    Hohenegger, Stefan; Iqbal, Amer; Rey, Soo-Jong

    2015-09-01

    We study relations between M-strings (one-dimensional intersections of M2-branes and M5-branes) in six dimensions and m-strings (magnetically charged monopole strings) in five dimensions. For specific configurations, we propose that the counting functions of Bogomol'nyi-Prasad-Sommerfield (BPS) bound states of M-strings capture the elliptic genus of the moduli space of m-strings. We check this proposal for the known cases, the Taub-NUT and Atiyah-Hitchin spaces, for which we find complete agreement. We further analyze the modular properties of the M-string free energies and find that they do not transform covariantly under S L (2 ,Z ). However, for a given number of M-strings, we show that there exists a unique combination of unrefined genus-zero free energies that transforms as a Jacobi form under a congruence subgroup of S L (2 ,Z ). These combinations correspond to summing over different numbers of M5-branes and make sense only if the distances between them are all equal. We explain that this is a necessary condition for the m-string moduli space to be factorizable into relative and center-of-mass parts.

  5. Sequestering in String Theory

    SciTech Connect

    Kachru, Shamit; McAllister, Liam; Sundrum, Raman

    2007-04-04

    We study sequestering, a prerequisite for flavor-blind supersymmetry breaking in several high-scale mediation mechanisms, in compactifications of type IIB string theory. We find that although sequestering is typically absent in unwarped backgrounds, strongly warped compactifications do readily sequester. The AdS/CFT dual description in terms of conformal sequestering plays an important role in our analysis, and we establish how sequestering works both on the gravity side and on the gauge theory side. We pay special attention to subtle compactification effects that can disrupt sequestering. Our result is a step toward realizing an appealing pattern of soft terms in a KKLT compactification.

  6. Nucleus from string theory

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji; Morita, Takeshi

    2011-08-01

    In generic holographic QCD, we find that baryons are bound to form a nucleus, and that its radius obeys the empirically-known mass-number (A) dependence r∝A1/3 for large A. Our result is robust, since we use only a generic property of D-brane actions in string theory. We also show that nucleons are bound completely in a finite volume. Furthermore, employing a concrete holographic model (derived by Hashimoto, Iizuka, and Yi, describing a multibaryon system in the Sakai-Sugimoto model), the nuclear radius is evaluated as O(1)×A1/3[fm], which is consistent with experiments.

  7. REACTOR CONTROL ROD OPERATING SYSTEM

    DOEpatents

    Miller, G.

    1961-12-12

    A nuclear reactor control rod mechanism is designed which mechanically moves the control rods into and out of the core under normal conditions but rapidly forces the control rods into the core by catapultic action in the event of an emergency. (AEC)

  8. Energy in a String Wave

    ERIC Educational Resources Information Center

    Ng, Chiu-king

    2010-01-01

    When one end of a taut horizontal elastic string is shaken repeatedly up and down, a transverse wave (assume sine waveform) will be produced and travel along it. College students know this type of wave motion well. They know when the wave passes by, each element of the string will perform an oscillating up-down motion, which in mechanics is termed…

  9. ISL - A String Manipulating Language.

    ERIC Educational Resources Information Center

    Kelley, K.C.; And Others.

    The Information Search Language (ISL), described in this report, is a problem-oriented language designed to facilitate the manipulation of real character strings with the Control Data 1604 computer. The report gives instructions for the language; these may be classified as Pseudo-ops, Word-Oriented instructions, Character-string instructions,…

  10. A Platonic Sextet for Strings

    ERIC Educational Resources Information Center

    Schaffer, Karl

    2012-01-01

    The use of traditional string figures by the Dr. Schaffer and Mr. Stern Dance Ensemble led to experimentation with polyhedral string constructions. This article presents a series of polyhedra made with six loops of three colors which sequence through all the Platonic Solids.

  11. Experimenting with String Musical Instruments

    ERIC Educational Resources Information Center

    LoPresto, Michael C.

    2012-01-01

    What follows are several investigations involving string musical instruments developed for and used in a "Science of Sound & Light" course. The experiments make use of a guitar, orchestral string instruments and data collection and graphing software. They are designed to provide students with concrete examples of how mathematical formulae, when…

  12. Improving cosmic string network simulations

    NASA Astrophysics Data System (ADS)

    Hindmarsh, Mark; Rummukainen, Kari; Tenkanen, Tuomas V. I.; Weir, David J.

    2014-08-01

    In real-time lattice simulations of cosmic strings in the Abelian Higgs model, the broken translational invariance introduces lattice artifacts; relativistic strings therefore decelerate and radiate. We introduce two different methods to construct a moving string on the lattice, and study in detail the lattice effects on moving strings. We find that there are two types of lattice artifact: there is an effective maximum speed with which a moving string can be placed on the lattice, and a moving string also slows down, with the deceleration approximately proportional to the exponential of the velocity. To mitigate this, we introduce and study an improved discretization, based on the tree-level Lüscher-Weisz action, which is found to reduce the deceleration by an order of magnitude, and to increase the string speed limit by an amount equivalent to halving the lattice spacing. The improved algorithm is expected to be very useful for 3D simulations of cosmic strings in the early Universe, where one wishes to simulate as large a volume as possible.

  13. French String Grammar. Final Report.

    ERIC Educational Resources Information Center

    New York Univ., NY. Linguistic String Project.

    This work reports on an initial study of the possibility of providing a suitable framework for the teaching of a foreign language grammar through string analysis, using French as the target language. Analysis of a string word list (word-class sequences) yields an overall view of the grammar. Details are furnished in a set of restrictions which…

  14. Solar-Cell String Conveyor

    NASA Technical Reports Server (NTRS)

    Frasch, W.; Ciavola, S.

    1982-01-01

    String-conveyor portion of solar-array assembly line holds silicon solar cells while assembled into strings and tested. Cells are transported collector-side-down, while uniform cell spacing and registration are maintained. Microprocessor on machine controls indexing of cells.

  15. Flat wormholes from cosmic strings.

    NASA Astrophysics Data System (ADS)

    Clement, G.

    1997-11-01

    The author describes the analytical extension of certain cylindrical multi-cosmic string metrics to wormhole spacetimes with only one region at spatial infinity, and investigates in detail the geometry of asymptotically Minkowskian wormhole spacetimes generated by one or two cosmic strings. It is found that such wormholes tend to lengthen rather than shorten space travel. Possible signatures of these wormholes are briefly discussed.

  16. String Mining in Bioinformatics

    NASA Astrophysics Data System (ADS)

    Abouelhoda, Mohamed; Ghanem, Moustafa

    Sequence analysis is a major area in bioinformatics encompassing the methods and techniques for studying the biological sequences, DNA, RNA, and proteins, on the linear structure level. The focus of this area is generally on the identification of intra- and inter-molecular similarities. Identifying intra-molecular similarities boils down to detecting repeated segments within a given sequence, while identifying inter-molecular similarities amounts to spotting common segments among two or multiple sequences. From a data mining point of view, sequence analysis is nothing but string- or pattern mining specific to biological strings. For a long time, this point of view, however, has not been explicitly embraced neither in the data mining nor in the sequence analysis text books, which may be attributed to the co-evolution of the two apparently independent fields. In other words, although the word “data-mining” is almost missing in the sequence analysis literature, its basic concepts have been implicitly applied. Interestingly, recent research in biological sequence analysis introduced efficient solutions to many problems in data mining, such as querying and analyzing time series [49,53], extracting information from web pages [20], fighting spam mails [50], detecting plagiarism [22], and spotting duplications in software systems [14].

  17. String Mining in Bioinformatics

    NASA Astrophysics Data System (ADS)

    Abouelhoda, Mohamed; Ghanem, Moustafa

    Sequence analysis is a major area in bioinformatics encompassing the methods and techniques for studying the biological sequences, DNA, RNA, and proteins, on the linear structure level. The focus of this area is generally on the identification of intra- and inter-molecular similarities. Identifying intra-molecular similarities boils down to detecting repeated segments within a given sequence, while identifying inter-molecular similarities amounts to spotting common segments among two or multiple sequences. From a data mining point of view, sequence analysis is nothing but string- or pattern mining specific to biological strings. For a long time, this point of view, however, has not been explicitly embraced neither in the data mining nor in the sequence analysis text books, which may be attributed to the co-evolution of the two apparently independent fields. In other words, although the word "data-mining" is almost missing in the sequence analysis literature, its basic concepts have been implicitly applied. Interestingly, recent research in biological sequence analysis introduced efficient solutions to many problems in data mining, such as querying and analyzing time series [49,53], extracting information from web pages [20], fighting spam mails [50], detecting plagiarism [22], and spotting duplications in software systems [14].

  18. Cosmic string wakes

    NASA Technical Reports Server (NTRS)

    Stebbins, Albert; Veeraraghavan, Shoba; Silk, Joseph; Brandenberger, Robert; Turok, Neil

    1987-01-01

    Accretion of matter onto wakes left behind by horizon-sized pieces of cosmic string is investigated, and the effects of wakes on the large-scale structure of the universe are determined. Accretion of cold matter onto wakes, the effects of a long string on fluids with finite velocity dispersion or sound speeds, the interactions between loops and wakes, and the conditions for wakes to survive disruption by loops are discussed. It is concluded that the most important wakes are those which were formed at the time of equal matter and radiation density. This leads to sheetlike overdense regions of galaxies with a mean separation in agreement with the scale of the bubbles of de Lapparent, Geller, and Huchra (1986). However, for the value of G(mu) favored from galaxy formation considerations in a universe with cold dark matter, a wake accretes matter from a distance of only about 1.5 Mpc, which is much less than the distance between the wakes.

  19. Summing Planar Bosonic Open Strings

    SciTech Connect

    Bardakci, Korkut

    2006-02-16

    In earlier work, planar graphs of massless {phi}{sup 3} theory were summed with the help of the light cone world sheet picture and the mean field approximation. In the present article, the same methods are applied to the problem of summing planar bosonic open strings. They find that in the ground state of the system, string boundaries form a condensate on the world sheet, and a new string emerges from this summation. Its slope is always greater than the initial slope, and it remains non-zero even when the initial slope is set equal to zero. If they assume the initial string tends to a field a theory in the zero slope limit, this result provides evidence for string formation in field theory.

  20. Number of cosmic string loops

    NASA Astrophysics Data System (ADS)

    Blanco-Pillado, Jose J.; Olum, Ken D.; Shlaer, Benjamin

    2014-01-01

    Using recent simulation results, we provide the mass and speed spectrum of cosmic string loops. This is the quantity of primary interest for many phenomenological signatures of cosmic strings, and it can be accurately predicted using recently acquired detailed knowledge of the loop production function. We emphasize that gravitational smoothing of long strings plays a negligible role in determining the total number of existing loops. We derive a bound on the string tension imposed by recent constraints on the stochastic gravitational wave background from pulsar timing arrays, finding Gμ ≤2.8×10-9. We also provide a derivation of the Boltzmann equation for cosmic string loops in the language of differential forms.

  1. Cosmic necklaces from string theory

    SciTech Connect

    Leblond, Louis; Wyman, Mark

    2007-06-15

    We present the properties of a cosmic superstring network in the scenario of flux compactification. An infinite family of strings, the (p,q) strings, are allowed to exist. The flux compactification leads to a string tension that is periodic in p. Monopoles, appearing here as beads on a string, are formed in certain interactions in such networks. This allows bare strings to become cosmic necklaces. We study network evolution in this scenario, outlining what conditions are necessary to reach a cosmologically viable scaling solution. We also analyze the physics of the beads on a cosmic necklace, and present general conditions for which they will be cosmologically safe, leaving the network's scaling undisturbed. In particular, we find that a large average loop size is sufficient for the beads to be cosmologically safe. Finally, we argue that loop formation will promote a scaling solution for the interbead distance in some situations.

  2. SAFETY SYSTEM FOR CONTROL ROD

    DOEpatents

    Paget, J.A.

    1963-05-14

    A structure for monitoring the structural continuity of a control rod foi a neutron reactor is presented. A electric conductor readily breakable under mechanical stress is fastened along the length of the control rod at a plurality of positions and forms a closed circuit with remote electrical components responsive to an open circuit. A portion of the conductor between the control rod and said components is helically wound to allow free and normally unrestricted movement of the segment of conductor secured to the control rod relative to the remote components. Any break in the circuit is indicative of control rod breakage. (AEC)

  3. Locked-wrap fuel rod

    DOEpatents

    Kaplan, Samuel; Chertock, Alan J.; Punches, James R.

    1977-01-01

    A method for spacing fast reactor fuel rods using a wire wrapper improved by orienting the wire-wrapped fuel rods in a unique manner which introduces desirable performance characteristics not attainable by previous wire-wrapped designs. Use of this method in a liquid metal fast breeder reactor results in: (a) improved mechanical performance, (b) improved rod-to-rod contact, (c) reduced steel volume, and (d) improved thermal-hydraulic performance. The method produces a "locked wrap" design which tends to lock the rods together at each of the wire cluster locations.

  4. Subcritical string and large N QCD

    SciTech Connect

    Thorn, Charles B.

    2008-10-15

    We pursue the possibility of using subcritical string theory in 4 spacetime dimensions to establish a string dual for large N QCD. In particular we study the even G-parity sector of the 4 dimensional Neveu-Schwarz dual resonance model as the natural candidate for this string theory. Our point of view is that the open string dynamics given by this model will determine the appropriate subcritical closed string theory, a tree level background of which should describe the sum of planar multiloop open string diagrams. We examine the one-loop open string diagram, which contains information about the closed string spectrum at weak coupling. Higher loop open string diagrams will be needed to determine closed string interactions. We also analyze the field theory limit of the one-loop open string diagram and recover the correct running coupling behavior of the limiting gauge theory.

  5. APPARATUS FOR SHEATHING RODS

    DOEpatents

    Ford, W.K.; Wyatt, M.; Plail, S.

    1961-08-01

    An arrangement is described for sealing a solid body of nuclear fuel, such as a uranium metal rod, into a closelyfitting thin metallic sheath with an internal atmosphere of inert gas. The sheathing process consists of subjecting the sheath, loaded with the nuclear fuel body, to the sequential operations of evacuation, gas-filling, drawing (to entrap inert gas and secure close contact between sheath and body), and sealing. (AEC)

  6. Safety rod latch inspection

    SciTech Connect

    Leader, D.R.

    1992-02-01

    During an attempt to raise control rods from the 100 K reactor in December, one rod could not be withdrawn. Subsequent investigation revealed that a small button'' in the latch mechanism had broken off of the lock plunger'' and was wedged in a position that prevented rod withdrawal. Concern that this failure may have resulted from corrosion or some other metallurgical problem resulted in a request that SRL examine six typical latch mechanisms from the 100 L reactor by use of radiography and metallography. During the examination of the L-Area latches, a failed latch mechanism from the 100 K reactor was added to the investigation. Fourteen latches that had a history of problems were removed from K-Area and sent to SRL for inclusion in this study the week after the original seven assemblies were examined, bringing the total of latch assemblies discussed in this report to twenty one. Results of the examination of the K-Area latch that initiated this study is not included in this report.

  7. Safety rod latch inspection

    SciTech Connect

    Leader, D.R.

    1992-02-01

    During an attempt to raise control rods from the 100 K reactor in December, one rod could not be withdrawn. Subsequent investigation revealed that a small ``button`` in the latch mechanism had broken off of the ``lock plunger`` and was wedged in a position that prevented rod withdrawal. Concern that this failure may have resulted from corrosion or some other metallurgical problem resulted in a request that SRL examine six typical latch mechanisms from the 100 L reactor by use of radiography and metallography. During the examination of the L-Area latches, a failed latch mechanism from the 100 K reactor was added to the investigation. Fourteen latches that had a history of problems were removed from K-Area and sent to SRL for inclusion in this study the week after the original seven assemblies were examined, bringing the total of latch assemblies discussed in this report to twenty one. Results of the examination of the K-Area latch that initiated this study is not included in this report.

  8. Rod locking device

    SciTech Connect

    Troxell, J.N. Jr.

    1986-07-22

    A ram locking apparatus used on a blowout preventer is described having a housing, a ram, ram actuating means having a closing side and a retracted side and a tail rod having its inner end connected to the ram actuating means and its outer end engaged by the apparatus to lock the ram. The apparatus consists of: a lock housing having a closed end and a hollow interior connected to the exterior of the preventer housing in which the tail rod is positioned, a body positioned within the lock housing, a primary piston, a lost motion connection between the primary piston and the body, a lock piston associated with the primary piston and movable axially with respect to the primary piston, a tapered split locking ring interconnected to the lock piston, wedging means with the split locking ring, and means for supplying fluid under pressure into the lock housing for movement of the pistons, the initial pressure on the primary pistons causing movement of the body to engage the ram tail rod and subsequently moving the lock piston relative to the wedging means and to thereby wedge the split locking ring against the interior of the lock housing to lock the body therein against movement in the lock housing.

  9. Life history and ecological characteristics of the Santa Ana sucker, Catostomus santaanae

    USGS Publications Warehouse

    Saiki, Michael K.; Martin, Barbara A.; Knowles, Glen W.; Tennant, Patrick W.

    2007-01-01

    This study was conducted to document the life history and ecological characteristics of the Santa Ana sucker, Catostomus santaanae, within its native range in southern California. Electrofishing surveys were conducted at 3-month intervals from December 1998 to December 1999 at one site on the San Gabriel River and two sites on the Santa Ana River. Suckers were captured in the San Gabriel River (average, 6.6 fish/10-minutes electrofishing) and at an upstream Santa Ana River site (average, 2.3 fish/10-minutes electrofishing) but not at a downstream Santa Ana River site. Length frequency distributions indicated that at least three year classes (modal groups) of suckers were present in the San Gabriel River, whereas one or two year classes were present in the Santa Ana River. Collection of 21-30 mm standard length (SL) juveniles in June in the Santa Ana River and in September in the San Gabriel River indicated that reproduction occurred over several months. In December, Age-0 suckers averaged 36-48 mm SL in the San Gabriel River and 63-65 mm SL in the Santa Ana River, whereas Age-1 suckers averaged 86 mm SL in the San Gabriel River and 115 mm SL in the Santa Ana River. On average, suckers were in better body condition in the San Gabriel River than in the Santa Ana River. Highest abundance of suckers was associated with relativelypristine environmental conditions (especially low specific conductance) where other native fishes were also common or abundant.

  10. Terahertz pinch harmonics enabled by single nano rods.

    PubMed

    Park, Hyeong-Ryeol; Bahk, Young-Mi; Choe, Jong Ho; Han, Sanghoon; Choi, Seong Soo; Ahn, Kwang Jun; Park, Namkyoo; Park, Q-Han; Kim, Dai-Sik

    2011-11-21

    A pinch harmonic (or guitar harmonic) is a musical note produced by lightly pressing the thumb of the picking hand upon the string immediately after it is picked [J. Chem. Educ. 84, 1287 (2007)]. This technique turns off the fundamental and all overtones except those with a node at that location. Here we present a terahertz analogue of pinch harmonics, whereby a metallic nano rod placed at a harmonic node on a terahertz nanoresonator suppresses the fundamental mode, making the higher harmonics dominant. Strikingly, a skin depth-wide nano rod placed at the mid-point turns off all resonances. Our work demonstrates that terahertz electromagnetic waves can be tailored by nanoparticles strategically positioned, paving important path towards terahertz switching and detection applications.

  11. Terahertz pinch harmonics enabled by single nano rods.

    PubMed

    Park, Hyeong-Ryeol; Bahk, Young-Mi; Choe, Jong Ho; Han, Sanghoon; Choi, Seong Soo; Ahn, Kwang Jun; Park, Namkyoo; Park, Q-Han; Kim, Dai-Sik

    2011-11-21

    A pinch harmonic (or guitar harmonic) is a musical note produced by lightly pressing the thumb of the picking hand upon the string immediately after it is picked [J. Chem. Educ. 84, 1287 (2007)]. This technique turns off the fundamental and all overtones except those with a node at that location. Here we present a terahertz analogue of pinch harmonics, whereby a metallic nano rod placed at a harmonic node on a terahertz nanoresonator suppresses the fundamental mode, making the higher harmonics dominant. Strikingly, a skin depth-wide nano rod placed at the mid-point turns off all resonances. Our work demonstrates that terahertz electromagnetic waves can be tailored by nanoparticles strategically positioned, paving important path towards terahertz switching and detection applications. PMID:22109504

  12. String bit models for superstring

    SciTech Connect

    Bergman, O.; Thorn, C.B.

    1995-12-31

    The authors extend the model of string as a polymer of string bits to the case of superstring. They mainly concentrate on type II-B superstring, with some discussion of the obstacles presented by not II-B superstring, together with possible strategies for surmounting them. As with previous work on bosonic string work within the light-cone gauge. The bit model possesses a good deal less symmetry than the continuous string theory. For one thing, the bit model is formulated as a Galilei invariant theory in (D {minus} 2) + 1 dimensional space-time. This means that Poincare invariance is reduced to the Galilei subgroup in D {minus} 2 space dimensions. Naturally the supersymmetry present in the bit model is likewise dramatically reduced. Continuous string can arise in the bit models with the formation of infinitely long polymers of string bits. Under the right circumstances (at the critical dimension) these polymers can behave as string moving in D dimensional space-time enjoying the full N = 2 Poincare supersymmetric dynamics of type II-B superstring.

  13. Wormholes in string theory

    SciTech Connect

    Lyons, A. ); Hawking, S.W. )

    1991-12-15

    We discuss the wormhole effective interactions in string theory, thought of as a sum over two-dimensional field theories on different world sheets. The effective interactions are calculated in the dilute wormhole approximation,'' initially by considering the Green's functions on higher-genus Riemann surfaces, and then by calculating the effect of a complete basis of wave functions on scattering amplitudes for a surface with a boundary. The sum over wormholes is equivalent to having a world sheet of trivial topology and summing over different space-time and matter-field backgrounds. To leading order these consist of the massless fluctuations, since the tachyon cancels out when a sum is done over different spin structures going through the wormhole. In this way we recover quantized general relativity as an effective theory, from a sum over field theories on higher-genus Riemann surfaces.

  14. A character string scanner

    NASA Technical Reports Server (NTRS)

    Enison, R. L.

    1971-01-01

    A computer program called Character String Scanner (CSS), is presented. It is designed to search a data set for any specified group of characters and then to flag this group. The output of the CSS program is a listing of the data set being searched with the specified group of characters being flagged by asterisks. Therefore, one may readily identify specific keywords, groups of keywords or specified lines of code internal to a computer program, in a program output, or in any other specific data set. Possible applications of this program include the automatic scan of an output data set for pertinent keyword data, the editing of a program to change the appearance of a certain word or group of words, and the conversion of a set of code to a different set of code.

  15. Supersymmetric string waves

    SciTech Connect

    Bergshoeff, E.A. ); Kallosh, R.; Ortin, T. )

    1993-06-15

    We present plane-wave-type solutions of the lowest-order superstring effective action which have unbroken space-time supersymmetries. They are given by a stringy generalization of the Brinkmann metric, dialton, axion, and gauge fields. Some conspiracy between the metric and the axion field is required. The [alpha][prime] stringy corrections to the effective on-shell action, to the equations of motion (and therefore to the solutions themselves), and to the supersymmetry transformations are shown to vanish for a special class of these solutions that we call supersymmetric string waves (SSW's). In the SSW solutions, there exists a conspiracy not only between the metric and the axion field, but also between the gauge fields and the metric, since the embedding of the spin connection in the gauge group is required.

  16. Dynamical evolution of cosmic strings

    SciTech Connect

    Bouchet, F.R.

    1988-05-11

    The author have studied by means of numerical simulations the dynamical evolution of a network of cosmic strings, both in the radiation and matter era. Our basic conclusion is that a scaling solution exists, i.e., the string energy density evolves as t/sup -2/. This means that the process by which long strings dump their energy into closed loops (which can gravitationally radiate away) is efficient enough to prevent the string domination over other forms of energy. This conclusion does not depend on the initial string energy density, nor on the various numerical parameters. On the other hand, the generated spectrum of loop sizes does depend on the value of our numerical lower cutoff (i.e., the minimum length of loop we allow to be chopped off the network). Furthermore, the network evolution is very different from what was assumed before), namely the creation of a few horizon sized loops per horizon volume and per hubble time, which subsequently fragment into about 10 smaller daughter loops. Rather, many tiny loops are directly cut from the network of infinite strings, and it appears that the only fundamental scale (the horizon) has been lost. This is probably because a fundamental ingredient had been overlooked, namely the kinks. These kinks are created in pairs at each intercommutation, and very rapidly, the long strings appear to be very kinky. Thus the number of long strings per horizon is still of the order of a few, but their total length is fairly large. Furthermore, a large number of kinks favors the formation of small loops, and their sizes might well be governed by the kink density along the long strings. Finally, we computed the two-point correlation function of the loops and found significant differences from the work of Turok.

  17. String Formatting Considered Harmful for Novice Programmers

    ERIC Educational Resources Information Center

    Hughes, Michael C.; Jadud, Matthew C.; Rodrigo, Ma. Mercedes T.

    2010-01-01

    In Java, "System.out.printf" and "String.format" consume a specialised kind of string commonly known as a format string. In our study of first-year students at the Ateneo de Manila University, we discovered that format strings present a substantial challenge for novice programmers. Focusing on their first laboratory we found that 8% of all the…

  18. Closed string amplitudes as single-valued open string amplitudes

    NASA Astrophysics Data System (ADS)

    Stieberger, Stephan; Taylor, Tomasz R.

    2014-04-01

    We show that the single trace heterotic N-point tree-level gauge amplitude ANHET can be obtained from the corresponding type I amplitude ANI by the single-valued (sv) projection: ANHET=sv(ANI). This projection maps multiple zeta values to single-valued multiple zeta values. The latter represent a subclass of multiple zeta values originating from single-valued multiple polylogarithms at unity. Similar relations between open and closed string amplitudes or amplitudes of different string vacua can be established. As a consequence the α‧-expansion of a closed string amplitude is dictated by that of the corresponding open string amplitude. The combination of single-valued projections, Kawai-Lewellen-Tye relations and Mellin correspondence reveal a unity of all tree-level open and closed superstring amplitudes together with the maximally supersymmetric Yang-Mills and supergravity theories.

  19. Worldsheet geometries of ambitwistor string

    NASA Astrophysics Data System (ADS)

    Ohmori, Kantaro

    2015-06-01

    Mason and Skinner proposed the ambitwistor string theory which directly reproduces the formulas for the amplitudes of massless particles proposed by Cachazo, He and Yuan. In this paper we discuss geometries of the moduli space of worldsheets associated to the bosonic or the RNS ambitwistor string. Further, we investigate the factorization properties of the amplitudes when an internal momentum is near on-shell in the abstract CFT language. Along the way, we propose the existence of the ambitwistor strings with three or four fermionic worldsheet currents.

  20. Geometry, topology, and string theory

    SciTech Connect

    Varadarajan, Uday

    2003-07-10

    A variety of scenarios are considered which shed light upon the uses and limitations of classical geometric and topological notions in string theory. The primary focus is on situations in which D-brane or string probes of a given classical space-time see the geometry quite differently than one might naively expect. In particular, situations in which extra dimensions, non-commutative geometries as well as other non-local structures emerge are explored in detail. Further, a preliminary exploration of such issues in Lorentzian space-times with non-trivial causal structures within string theory is initiated.

  1. Overview of Endangered Suckers in the Klamath Basin: Does it Take One to Know One?

    NASA Astrophysics Data System (ADS)

    Shively, R. S.; Vanderkooi, S.

    2005-12-01

    Severe water quality problems in the Klamath Basin of Oregon and California have led to critical fisheries concerns for the region. In the Upper Klamath Basin, two fish species, the Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were listed as federally endangered in 1988. These species are large, long-lived, lake-dwelling fishes endemic to the Upper Klamath Basin. Declining population trends for both species were noted as early as the mid 1960's, however, the severity of these declines were not evident until the mid 1980's. At the time of listing, population structures were dominated by older individuals with little evidence of recent significant recruitment into adult populations. In the early 1990s there was evidence of recruitment for Lost River suckers. Successive years of large fish kills in Upper Klamath Lake from 1995 to 1997, however, substantially reduced adult populations of both Lost River and shortnose suckers. Additionally, the 1995 and 1996 fish kills appeared to have been selective for larger-sized individuals and would have disproportionately affected females and resulted in an overall lower reproductive potential. Water quality and physical habitat limitations are considered to be the most limiting factors to species recovery. Life history patterns of Lost River and shortnose suckers in Upper Klamath Lake have been severely disrupted by recurrent periods of poor water quality that appear to be the root cause of fish kills and likely negatively influence the production of juvenile suckers. Habitat degradation around Upper Klamath Lake and in its tributaries likely contributes to water quality problems and also limits the physical habitat needed for successful adult sucker spawning as well as larval and juvenile rearing. Ultimately, a better understanding of the factors that influence water quality in Upper Klamath Lake as well as developing a sound strategy for habitat restoration is needed to promote recovery

  2. Perturbations from strings don't look like strings!

    NASA Technical Reports Server (NTRS)

    Albrecht, Andreas; Stebbins, Albert

    1991-01-01

    A systematic analysis is challenging popular ideas about perturbation from cosmic strings. One way in which the picture has changed is reviewed. It is concluded that, while the scaling properties of cosmic strings figure significantly in the analysis, care must be taken when thinking in terms of single time snapshots. The process of seeding density perturbations is not fundamentally localized in time, and this fact can wash out many of the details which appear in a single snapshot.

  3. 75 FR 5279 - Sucker Creek Channel and Floodplain Restoration Project (Phase II), Rogue River-Siskiyou National...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-02

    ...; ] DEPARTMENT OF AGRICULTURE Forest Service Sucker Creek Channel and Floodplain Restoration Project (Phase II..., Oregon. Purpose and Need for Action The purpose of the Sucker Creek Channel and Floodplain Restoration... show that the stream channel was more sinuous and contained a larger floodplain, characteristic of...

  4. Cosmic string catalysis of skyrmion decay

    NASA Technical Reports Server (NTRS)

    Gregory, Ruth; Davis, Anne-Christine; Brandenberger, Robert

    1988-01-01

    The Callan-Witten picture is developed for monopole catalyzed skyrmion decay in order to analyze the corresponding cosmic string scenario. It is discovered that cosmic strings (both ordinary and superconducting) can catalyze proton decay, but that this catalysis only occurs on the scale of the core of the string. In order to do this we have to develop a vortex model for the superconducting string. An argument is also given for the difference in the enhancement factors for monopoles and strings.

  5. Classification of cohomogeneity-one strings

    SciTech Connect

    Ishihara, Hideki; Kozaki, Hiroshi

    2005-09-15

    We define the cohomogeneity one string, string with continuous symmetries, as its world surface is tangent to a Killing vector field of a target space. We classify the Killing vector fields by an equivalence relation using isometries of the target space. We find that the equivalence classes of Killing vectors in Minkowski spacetime are partitioned into seven families. It is clarified that there exist seven types of strings with spacelike symmetries and four types of strings with timelike symmetries, stationary strings.

  6. Charting the landscape of supercritical string theory.

    PubMed

    Hellerman, Simeon; Swanson, Ian

    2007-10-26

    Special solutions of string theory in supercritical dimensions can interpolate in time between theories with different numbers of spacetime dimensions and different amounts of world sheet supersymmetry. These solutions connect supercritical string theories to the more familiar string duality web in ten dimensions and provide a precise link between supersymmetric and purely bosonic string theories. Dimension quenching and c duality appear to be natural concepts in string theory, giving rise to large networks of interconnected theories.

  7. Fiber optic laser rod

    DOEpatents

    Erickson, G.F.

    1988-04-13

    A laser rod is formed from a plurality of optical fibers, each forming an individual laser. Synchronization of the individual fiber lasers is obtained by evanescent wave coupling between adjacent optical fiber cores. The fiber cores are dye-doped and spaced at a distance appropriate for evanescent wave coupling at the wavelength of the selected dye. An interstitial material having an index of refraction lower than that of the fiber core provides the optical isolation for effective lasing action while maintaining the cores at the appropriate coupling distance. 2 figs.

  8. Cone rod dystrophies.

    PubMed

    Hamel, Christian P

    2007-01-01

    Cone rod dystrophies (CRDs) (prevalence 1/40,000) are inherited retinal dystrophies that belong to the group of pigmentary retinopathies. CRDs are characterized by retinal pigment deposits visible on fundus examination, predominantly localized to the macular region. In contrast to typical retinitis pigmentosa (RP), also called the rod cone dystrophies (RCDs) resulting from the primary loss in rod photoreceptors and later followed by the secondary loss in cone photoreceptors, CRDs reflect the opposite sequence of events. CRD is characterized by primary cone involvement, or, sometimes, by concomitant loss of both cones and rods that explains the predominant symptoms of CRDs: decreased visual acuity, color vision defects, photoaversion and decreased sensitivity in the central visual field, later followed by progressive loss in peripheral vision and night blindness. The clinical course of CRDs is generally more severe and rapid than that of RCDs, leading to earlier legal blindness and disability. At end stage, however, CRDs do not differ from RCDs. CRDs are most frequently non syndromic, but they may also be part of several syndromes, such as Bardet Biedl syndrome and Spinocerebellar Ataxia Type 7 (SCA7). Non syndromic CRDs are genetically heterogeneous (ten cloned genes and three loci have been identified so far). The four major causative genes involved in the pathogenesis of CRDs are ABCA4 (which causes Stargardt disease and also 30 to 60% of autosomal recessive CRDs), CRX and GUCY2D (which are responsible for many reported cases of autosomal dominant CRDs), and RPGR (which causes about 2/3 of X-linked RP and also an undetermined percentage of X-linked CRDs). It is likely that highly deleterious mutations in genes that otherwise cause RP or macular dystrophy may also lead to CRDs. The diagnosis of CRDs is based on clinical history, fundus examination and electroretinogram. Molecular diagnosis can be made for some genes, genetic counseling is always advised. Currently

  9. Reactor control rod timing system

    DOEpatents

    Wu, Peter T. K.

    1982-01-01

    A fluid driven jet-edge whistle timing system for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  10. Reactor control rod timing system

    SciTech Connect

    Wu, P.T.

    1982-02-09

    A fluid driven jet-edge whistle timing system for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (Above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  11. Hierarchical Nanostructures Self-Assembled from a Mixture System Containing Rod-Coil Block Copolymers and Rigid Homopolymers

    PubMed Central

    Li, Yongliang; Jiang, Tao; Lin, Shaoliang; Lin, Jiaping; Cai, Chunhua; Zhu, Xingyu

    2015-01-01

    Self-assembly behavior of a mixture system containing rod-coil block copolymers and rigid homopolymers was investigated by using Brownian dynamics simulations. The morphologies of formed hierarchical self-assemblies were found to be dependent on the Lennard-Jones (LJ) interaction εRR between rod blocks, lengths of rod and coil blocks in copolymer, and mixture ratio of block copolymers to homopolymers. As the εRR value decreases, the self-assembled structures of mixtures are transformed from an abacus-like structure to a helical structure, to a plain fiber, and finally are broken into unimers. The order parameter of rod blocks was calculated to confirm the structure transition. Through varying the length of rod and coil blocks, the regions of thermodynamic stability of abacus, helix, plain fiber, and unimers were mapped. Moreover, it was discovered that two levels of rod block ordering exist in the helices. The block copolymers are helically wrapped on the homopolymer bundles to form helical string, while the rod blocks are twistingly packed inside the string. In addition, the simulation results are in good agreement with experimental observations. The present work reveals the mechanism behind the formation of helical (experimentally super-helical) structures and may provide useful information for design and preparation of the complex structures. PMID:25965726

  12. Hierarchical Nanostructures Self-Assembled from a Mixture System Containing Rod-Coil Block Copolymers and Rigid Homopolymers

    NASA Astrophysics Data System (ADS)

    Li, Yongliang; Jiang, Tao; Lin, Shaoliang; Lin, Jiaping; Cai, Chunhua; Zhu, Xingyu

    2015-05-01

    Self-assembly behavior of a mixture system containing rod-coil block copolymers and rigid homopolymers was investigated by using Brownian dynamics simulations. The morphologies of formed hierarchical self-assemblies were found to be dependent on the Lennard-Jones (LJ) interaction ɛRR between rod blocks, lengths of rod and coil blocks in copolymer, and mixture ratio of block copolymers to homopolymers. As the ɛRR value decreases, the self-assembled structures of mixtures are transformed from an abacus-like structure to a helical structure, to a plain fiber, and finally are broken into unimers. The order parameter of rod blocks was calculated to confirm the structure transition. Through varying the length of rod and coil blocks, the regions of thermodynamic stability of abacus, helix, plain fiber, and unimers were mapped. Moreover, it was discovered that two levels of rod block ordering exist in the helices. The block copolymers are helically wrapped on the homopolymer bundles to form helical string, while the rod blocks are twistingly packed inside the string. In addition, the simulation results are in good agreement with experimental observations. The present work reveals the mechanism behind the formation of helical (experimentally super-helical) structures and may provide useful information for design and preparation of the complex structures.

  13. Hierarchical nanostructures self-assembled from a mixture system containing rod-coil block copolymers and rigid homopolymers.

    PubMed

    Li, Yongliang; Jiang, Tao; Lin, Shaoliang; Lin, Jiaping; Cai, Chunhua; Zhu, Xingyu

    2015-05-12

    Self-assembly behavior of a mixture system containing rod-coil block copolymers and rigid homopolymers was investigated by using Brownian dynamics simulations. The morphologies of formed hierarchical self-assemblies were found to be dependent on the Lennard-Jones (LJ) interaction εRR between rod blocks, lengths of rod and coil blocks in copolymer, and mixture ratio of block copolymers to homopolymers. As the εRR value decreases, the self-assembled structures of mixtures are transformed from an abacus-like structure to a helical structure, to a plain fiber, and finally are broken into unimers. The order parameter of rod blocks was calculated to confirm the structure transition. Through varying the length of rod and coil blocks, the regions of thermodynamic stability of abacus, helix, plain fiber, and unimers were mapped. Moreover, it was discovered that two levels of rod block ordering exist in the helices. The block copolymers are helically wrapped on the homopolymer bundles to form helical string, while the rod blocks are twistingly packed inside the string. In addition, the simulation results are in good agreement with experimental observations. The present work reveals the mechanism behind the formation of helical (experimentally super-helical) structures and may provide useful information for design and preparation of the complex structures.

  14. String and Sticky Tape Experiments.

    ERIC Educational Resources Information Center

    Edge, R. D., Ed.

    1979-01-01

    Explains how to demonstrate the fundamentals of one dimensional kinematics such as Newton's third law of motion, and collision between bodies, using simple materials of marbles, strings, sticky tape, drinking straws, and rubber bands. (GA)

  15. Spin chains and string theory.

    PubMed

    Kruczenski, Martin

    2004-10-15

    Recently, an important test of the anti de Sitter/conformal field theory correspondence has been done using rotating strings with two angular momenta. We show that such a test can be described more generally as the agreement between two actions: one a low energy description of a spin chain appearing in the field theory side, and the other a limit of the string action in AdS5xS5. This gives a map between the mean value of the spin in the boundary theory and the position of the string in the bulk, and shows how a string action can emerge from a gauge theory in the large-N limit.

  16. Performance of drill string hardfacings

    SciTech Connect

    Williamson, J.S.; Bolton, J.

    1984-06-01

    Drill string hardfacings are composites of steel and tungsten carbide applied by welding techniques. This paper discusses the important variables involved and gives experimental results for casing wear and abrasive wear resistance.

  17. Nuclear Force from String Theory

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji

    2010-04-01

    Recent "technology" called holography, or gauge/string duality (AdS/CFT correspondence) found in string theory, makes it possible to compute various quantities of strongly coupled gauge theories. This technology was applied to QCD, and it was found that it describes surprisingly well important properties of low energy QCD, the hadron physics. We apply it further to nuclear physics. In this talk, I review a part of the developments of the holographic QCD, and show a computation of nuclear force at short distance, derived using the holographic QCD, which was done in collaboration with T. Sakai and S. Sugimoto [K. Hashimoto, T. Sakai, and S. Sugimoto, "Holographic Baryons: Static Properties and Form Factors from Gauge/String Duality," Prog. Theor. Phys. 120 (2008) 1093-1137, arXiv:0806.3122 [hep-th]; K. Hashimoto, T. Sakai, and S. Sugimoto, "Nuclear Force from String Theory," arXiv:0901.4449 [hep-th

  18. Selenium impacts on razorback sucker, Colorado: Colorado River: III. Larvae

    USGS Publications Warehouse

    Hamilton, S.J.; Holley, K.M.; Buhl, K.J.; Bullard, F.A.

    2005-01-01

    Razorback sucker (Xyrauchen texanus) larvae from adults exposed to selenium at three sites near Grand Junction, Colorado, for 9 months were used in a 30-day waterborne and dietary selenium study. Selenium concentrations in water averaged <1.6 ??g/L from 24-Road, 0.9 ??g/L from Horsethief, 5.5 ??g/L from Adobe Creek, and 10.7 ??g/L from the North Pond. Selenium in dietary items averaged 2.7 ??g/g in brine shrimp, 5.6 ??g/g in zooplankton from Horsethief east wetland, 20 ??g/g in zooplankton from Adobe Creek, and 39 ??g/g in zooplankton from North Pond. The lowest survival occurred in larvae fed zooplankton rather than brine shrimp. Survival of larvae at Adobe Creek and North Pond was lower in site water than in reference water. Survival of brood stock larvae was higher than Horsethief larvae even though they received the same water and dietary treatments. Arsenic concentrations in brine shrimp may have resulted in an antagonistic interaction with selenium and reduced adverse effects in larvae. Deformities in larvae from North Pond were similar to those reported for selenium-induced teratogenic deformities in other fish species. Selenium concentrations of ???4.6 ??g/g in food resulted in rapid mortality of larvae from Horsethief, Adobe Creek, and North Pond, and suggested that selenium toxicity in the Colorado River could limit recovery of this endangered fish.

  19. Selenium impacts on razorback sucker, Colorado River, Colorado: II. Eggs

    USGS Publications Warehouse

    Hamilton, S.J.; Holley, K.M.; Buhl, K.J.; Bullard, F.A.

    2005-01-01

    Effects on hatching and development of fertilized eggs in adult razorback sucker (Xyrauchen texanus) exposed to selenium in flooded bottomland sites near Grand Junction, Colorado, were determined. After 9 months exposure, fish were collected and induced to spawn and eggs collected for inorganic element analyses. A 9-day egg study was conducted with five spawns from Horsethief ponds, six spawns from Adobe Creek channel, and four spawns from North Pond using a reference water and site waters. Selenium concentrations in eggs were 6.5 ??g/g from Horsethief, 46 ??g/g from Adobe Creek, 38 ??g/g from North Pond, and 6.0 ??g/g from brood stock. Eggs from young adults had a smaller diameter and higher moisture content than brood stock. There were no differences among the four sources in viability, survival, hatch, hatchability, or mortality of deformed embryos or larvae. Adobe Creek larvae had more deformed embryos in eggs held in site water than held in reference water. There were significant negative correlations between selenium concentrations in adult muscle plugs and percent hatch, egg diameter, and deformities in embryos. Results from this study suggest that selenium contamination in parts of the upper basin of the Colorado River should be a major concern to recovery efforts for endangered fish.

  20. Selenium impacts on razorback sucker, Colorado: Colorado River III. Larvae.

    PubMed

    Hamilton, Steven J; Holley, Kathy M; Buhl, Kevin J; Bullard, Fern A

    2005-06-01

    Razorback sucker (Xyrauchen texanus) larvae from adults exposed to selenium at three sites near Grand Junction, Colorado, for 9 months were used in a 30-day waterborne and dietary selenium study. Selenium concentrations in water averaged <1.6 microg/L from 24-Road, 0.9 microg/L from Horsethief, 5.5 microg/L from Adobe Creek, and 10.7 microg/L from the North Pond. Selenium in dietary items averaged 2.7 microg/g in brine shrimp, 5.6 microg/g in zooplankton from Horsethief east wetland, 20 microg/g in zooplankton from Adobe Creek, and 39 microg/g in zooplankton from North Pond. The lowest survival occurred in larvae fed zooplankton rather than brine shrimp. Survival of larvae at Adobe Creek and North Pond was lower in site water than in reference water. Survival of brood stock larvae was higher than Horsethief larvae even though they received the same water and dietary treatments. Arsenic concentrations in brine shrimp may have resulted in an antagonistic interaction with selenium and reduced adverse effects in larvae. Deformities in larvae from North Pond were similar to those reported for selenium-induced teratogenic deformities in other fish species. Selenium concentrations of 4.6 microg/g in food resulted in rapid mortality of larvae from Horsethief, Adobe Creek, and North Pond, and suggested that selenium toxicity in the Colorado River could limit recovery of this endangered fish.

  1. Coupled economic-coastline modeling with suckers and free riders

    NASA Astrophysics Data System (ADS)

    Williams, Zachary C.; McNamara, Dylan E.; Smith, Martin D.; Murray, A. Brad.; Gopalakrishnan, Sathya

    2013-06-01

    erosion is a natural trend along most sandy coastlines. Humans often respond to shoreline erosion with beach nourishment to maintain coastal property values. Locally extending the shoreline through nourishment alters alongshore sediment transport and changes shoreline dynamics in adjacent coastal regions. If left unmanaged, sandy coastlines can have spatially complex or simple patterns of erosion due to the relationship of large-scale morphology and the local wave climate. Using a numerical model that simulates spatially decentralized and locally optimal nourishment decisions characteristic of much of U.S. East Coast beach management, we find that human erosion intervention does not simply reflect the alongshore erosion pattern. Spatial interactions generate feedbacks in economic and physical variables that lead to widespread emergence of "free riders" and "suckers" with subsequent inequality in the alongshore distribution of property value. Along cuspate coastlines, such as those found along the U.S. Southeast Coast, these long-term property value differences span an order of magnitude. Results imply that spatially decentralized management of nourishment can lead to property values that are divorced from spatial erosion signals; this management approach is unlikely to be optimal.

  2. Selenium impacts on razorback sucker, Colorado: Colorado River III. Larvae.

    PubMed

    Hamilton, Steven J; Holley, Kathy M; Buhl, Kevin J; Bullard, Fern A

    2005-06-01

    Razorback sucker (Xyrauchen texanus) larvae from adults exposed to selenium at three sites near Grand Junction, Colorado, for 9 months were used in a 30-day waterborne and dietary selenium study. Selenium concentrations in water averaged <1.6 microg/L from 24-Road, 0.9 microg/L from Horsethief, 5.5 microg/L from Adobe Creek, and 10.7 microg/L from the North Pond. Selenium in dietary items averaged 2.7 microg/g in brine shrimp, 5.6 microg/g in zooplankton from Horsethief east wetland, 20 microg/g in zooplankton from Adobe Creek, and 39 microg/g in zooplankton from North Pond. The lowest survival occurred in larvae fed zooplankton rather than brine shrimp. Survival of larvae at Adobe Creek and North Pond was lower in site water than in reference water. Survival of brood stock larvae was higher than Horsethief larvae even though they received the same water and dietary treatments. Arsenic concentrations in brine shrimp may have resulted in an antagonistic interaction with selenium and reduced adverse effects in larvae. Deformities in larvae from North Pond were similar to those reported for selenium-induced teratogenic deformities in other fish species. Selenium concentrations of 4.6 microg/g in food resulted in rapid mortality of larvae from Horsethief, Adobe Creek, and North Pond, and suggested that selenium toxicity in the Colorado River could limit recovery of this endangered fish. PMID:15883090

  3. String resonances at hadron colliders

    NASA Astrophysics Data System (ADS)

    Anchordoqui, Luis A.; Antoniadis, Ignatios; Dai, De-Chang; Feng, Wan-Zhe; Goldberg, Haim; Huang, Xing; Lüst, Dieter; Stojkovic, Dejan; Taylor, Tomasz R.

    2014-09-01

    We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale Ms is in the TeV range and that the theory is weakly coupled, we discuss possible signals of string physics at the upcoming HL-LHC run (integrated luminosity =3000 fb-1) with a center-of-mass energy of √s =14 TeV and at potential future pp colliders, HE-LHC and VLHC, operating at √s =33 and 100 TeV, respectively (with the same integrated luminosity). In such D-brane constructions, the dominant contributions to full-fledged string amplitudes for all the common QCD parton subprocesses leading to dijets and γ +jet are completely independent of the details of compactification and can be evaluated in a parameter-free manner. We make use of these amplitudes evaluated near the first (n=1) and second (n=2) resonant poles to determine the discovery potential for Regge excitations of the quark, the gluon, and the color singlet living on the QCD stack. We show that for string scales as large as 7.1 TeV (6.1 TeV) lowest massive Regge excitations are open to discovery at the ≥5σ in dijet (γ +jet) HL-LHC data. We also show that for n=1 the dijet discovery potential at HE-LHC and VLHC exceedingly improves: up to 15 TeV and 41 TeV, respectively. To compute the signal-to-noise ratio for n=2 resonances, we first carry out a complete calculation of all relevant decay widths of the second massive level string states (including decays into massless particles and a massive n=1 and a massless particle), where we rely on factorization and conformal field theory techniques. Helicity wave functions of arbitrary higher spin massive bosons are also constructed. We demonstrate that for string scales Ms≲10.5 TeV (Ms≲28 TeV) detection of n =2 Regge recurrences at HE-LHC (VLHC) would become the smoking gun for D

  4. Automatic safety rod for reactors

    DOEpatents

    Germer, John H.

    1988-01-01

    An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-core flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

  5. Piston and connecting rod assembly

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor); Chatten, John K. (Inventor)

    2001-01-01

    A piston and connecting rod assembly includes a piston crown, a piston skirt, a connecting rod, and a bearing insert. The piston skirt is a component separate from the piston crown and is connected to the piston crown to provide a piston body. The bearing insert is a component separate from the piston crown and the piston skirt and is fixedly disposed within the piston body. A bearing surface of a connecting rod contacts the bearing insert to thereby movably associate the connecting rod and the piston body.

  6. Geometric precipices in string cosmology

    SciTech Connect

    Kaloper, Nemanja; Watson, Scott

    2008-03-15

    We consider the effects of graviton multiplet fields on transitions between string gas phases. Focusing on the dilaton field, we show that it may obstruct transitions between different thermodynamic phases of the string gas, because the sign of its dimensionally reduced, T-duality invariant, part is conserved when the energy density of the Universe is positive. Thus, many interesting solutions for which this sign is positive end up in a future curvature singularity. Because of this, some of the thermodynamic phases of the usual gravitating string gases behave like superselection sectors. For example, a past-regular Hagedorn phase and an expanding Friedmann-Robertson-Walker (FRW) phase dominated by string momentum modes cannot be smoothly connected in the framework of string cosmology with positive sources. The singularity separates them like a geometric precipice in the moduli space, preventing the dynamics of the theory from bridging across. Sources which simultaneously violate the positivity of energy and null energy condition (NEC) could modify these conclusions. We provide a quantitative measure of positivity of energy and NEC violations that would be necessary for such transitions. These effects must dominate the Universe at the moment of transition, altering the standard gas pictures. At present, it is not known how to construct such sources from first principles in string theory.

  7. String theory on the edge

    SciTech Connect

    Thorlacius, L.

    1989-01-01

    Open string vacuum configurations are described in terms of a one-dimensional field theory on the worldsheet boundary. The one-dimensional path integral has direct physical interpretation as a source term for closed string fields. This means that the vacuum divergences (Mobius infinities) of the path integral must be renormalized correctly. The author shows that reparametrization invariance Ward identities, apart from specifying the equations of motion of spacetime background gauge fields, also serve to fix the renormalization scheme of the vacuum divergences. He argues that vacuum configurations of open strings correspond to Caldeira-Leggett models of dissipative quantum mechanics (DQM) evaluated at a delocalization critical point. This connection reveals that critical DQM will manifest reparametrization invariance (inherited from the conformal invariance of string theory) rather than just scale invariance. This connection should open up new ways of constructing analytic and approximate solutions of open string theory (in particular, topological solitons such as monopoles and instantons). Type I superstring theory gives rise to a supersymmetric boundary field theory. Bose-Fermi cancellation eliminates vacuum divergences but the one-loop beta function remains the same as in the bosonic theory. Reparametrization invariance Ward identities dictate a boundary state normalization which yields consistent string-loop corrections to spacetime equations of motion, in both the periodic and anti-periodic fermion sectors.

  8. Predation on larval suckers in the Williamson River Delta revealed by molecular genetic assays—A pilot study

    USGS Publications Warehouse

    Hereford, Danielle M.; Ostberg, Carl O.; Burdick, Summer M.

    2016-06-13

    Predation of endangered Lost River suckers (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) during larval egress to Upper Klamath Lake from the Williamson River is poorly understood but may be an important factor limiting recruitment into adult spawning populations. Native and non-native piscivores are abundant in nursery wetland habitat, but larval predation has not been directly studied for all species. Larvae lack hard body structures and digest rapidly in predator digestive systems. Therefore, traditional visual methods for diet analysis may fail to identify the extent of predation on larvae. The goals of this study were to (1) use quantitative polymerase chain reaction (qPCR) and single nucleotide polymorphism (SNP) assays developed for Lost River and shortnose suckers to assay predator stomach contents for sucker DNA, and (2) to assess our ability to use this technique to study predation. Predators were captured opportunistically during larval sucker egress. Concurrent feeding trials indicate that most predators—yellow perch (Perca flaverscens), fathead minnow (Pimephales promelas), blue chub (Gila coerulea), Klamath tui chub (Siphatales bicolor bicolor), Klamath Lake sculpin (Cottus princeps), slender sculpin (Cottus tenuis)—preyed on sucker larvae in the laboratory. However, sucker DNA was not detected in fathead minnow stomachs. Of the stomachs screened from fish captured in the Williamson River Delta, 15.6 percent of yellow perch contained sucker DNA. This study has demonstrated that the application of qPCR and SNP assays is effective for studying predation on larval suckers. We suggest that techniques associated with dissection or detection of sucker DNA from fathead minnow stomachs need improvement.

  9. Predation on larval suckers in the Williamson River Delta revealed by molecular genetic assays—A pilot study

    USGS Publications Warehouse

    Hereford, Danielle M.; Ostberg, Carl O.; Burdick, Summer M.

    2016-01-01

    Predation of endangered Lost River suckers (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) during larval egress to Upper Klamath Lake from the Williamson River is poorly understood but may be an important factor limiting recruitment into adult spawning populations. Native and non-native piscivores are abundant in nursery wetland habitat, but larval predation has not been directly studied for all species. Larvae lack hard body structures and digest rapidly in predator digestive systems. Therefore, traditional visual methods for diet analysis may fail to identify the extent of predation on larvae. The goals of this study were to (1) use quantitative polymerase chain reaction (qPCR) and single nucleotide polymorphism (SNP) assays developed for Lost River and shortnose suckers to assay predator stomach contents for sucker DNA, and (2) to assess our ability to use this technique to study predation. Predators were captured opportunistically during larval sucker egress. Concurrent feeding trials indicate that most predators—yellow perch (Perca flaverscens), fathead minnow (Pimephales promelas), blue chub (Gila coerulea), Klamath tui chub (Siphatales bicolor bicolor), Klamath Lake sculpin (Cottus princeps), slender sculpin (Cottus tenuis)—preyed on sucker larvae in the laboratory. However, sucker DNA was not detected in fathead minnow stomachs. Of the stomachs screened from fish captured in the Williamson River Delta, 15.6 percent of yellow perch contained sucker DNA. This study has demonstrated that the application of qPCR and SNP assays is effective for studying predation on larval suckers. We suggest that techniques associated with dissection or detection of sucker DNA from fathead minnow stomachs need improvement.

  10. Unveiling the morphology of the acetabulum in octopus suckers and its role in attachment

    PubMed Central

    Tramacere, Francesca; Pugno, Nicola M.; Kuba, Michael J.; Mazzolai, Barbara

    2015-01-01

    In recent years, the attachment mechanism of the octopus sucker has attracted the interest of scientists from different research areas, including biology, engineering, medicine and robotics. From a technological perspective, the main goal is to identify the underlying mechanisms involved in sucker attachment for use in the development of new generations of artificial devices and materials. Recently, the understanding of the morphology of the sucker has been significantly improved; however, the mechanisms that allow attachment remain largely unknown. In this work, we present new anatomical findings: specifically, a protuberance in the acetabular roof in five different octopus species; previously, this protuberance was identified by the authors in Octopus vulgaris. Moreover, we discuss the role of the protuberance and other anatomical structures in attachment with minimal energy consumption. PMID:25657834

  11. Factors affecting condition of flannelmouth suckers in the Colorado River, Grand Canyon, Arizona

    USGS Publications Warehouse

    Paukert, C.; Rogers, R.S.

    2004-01-01

    The impoundment of the Colorado River by Glen Canyon Dam, Arizona, in 1963 created a highly regulated environment in the Grand Canyon that altered the native fish populations, including the flannelmouth sucker Catostomus latipinnis. Flannelmouth suckers were sampled from 1991 to 2001 to determine seasonal, annual, and spatial trends in fish condition (i.e., relative weight [Wr]). Mean Wr peaked during the prespawn and spawning periods and was lowest in summer and fall, but it was never lower than 93. Condition was variable throughout the Grand Canyon but was typically greatest at intermediate distances from Glen Canyon Dam, possibly because of the increased number of warmwater tributaries in this reach. Flannelmouth sucker condition in September was positively correlated with Glen Canyon Dam discharge during summer (June-August); this result may be due to the larger euphotic zone and greater macroinvertebrate abundance observed during higher water flows. Increased dam discharge that stimulates river productivity may provide benefits for this native fish.

  12. Wellhead leak containment

    SciTech Connect

    Evans, V.R.

    1990-08-21

    This patent describes an improvement in apparatus for producing fluid from a wellbore in the earth wherein the wellbore is capped at the surface of the earth with a wellhead. The wellhead being adapted for use with a reciprocating downhole rod pump which is carried by a sucker-rod string that extends from the downhole pump through the wellhead and connects with a reciprocating pumping unit on the earth's surface. The pumping unit being operated by a power plant means. The improvement comprising a catch basin carried by the wellhead in the vicinity where the sucker-rod string exits from the wellhead.

  13. Development of 20 TaqMan assays differentiating the endangered shortnose and Lost River suckers

    USGS Publications Warehouse

    Hoy, Marshal S.; Ostberg, Carl O.

    2015-01-01

    Accurate species identification is vital to conservation and management of species at risk. Species identification is challenging when taxa express similar phenotypic characters and form hybrids, for example the endangered shortnose sucker (Chasmistes brevirostris) and Lost River sucker (Deltistes luxatus). Here, we developed 20 Taqman assays that differentiate these species (19 nuclear DNA and one mitochondrial DNA). Assays were evaluated in 160 young-of-the-year identified to species using meristic counts. Alleles were not fixed between species, but species were highly differentiated (F ST = 0.753, P < 0.001). The assays developed herein will be a valuable tool for resource managers.

  14. Threading plasmonic nanoparticle strings with light

    PubMed Central

    Herrmann, Lars O.; Valev, Ventsislav K.; Tserkezis, Christos; Barnard, Jonathan S.; Kasera, Setu; Scherman, Oren A.; Aizpurua, Javier; Baumberg, Jeremy J.

    2014-01-01

    Nanomaterials find increasing application in communications, renewable energies, electronics and sensing. Because of its unsurpassed speed and highly tuneable interaction with matter, using light to guide the self-assembly of nanomaterials can open up novel technological frontiers. However, large-scale light-induced assembly remains challenging. Here we demonstrate an efficient route to nano-assembly through plasmon-induced laser threading of gold nanoparticle strings, producing conducting threads 12±2 nm wide. This precision is achieved because the nanoparticles are first chemically assembled into chains with rigidly controlled separations of 0.9 nm primed for re-sculpting. Laser-induced threading occurs on a large scale in water, tracked via a new optical resonance in the near-infrared corresponding to a hybrid chain/rod-like charge transfer plasmon. The nano-thread width depends on the chain mode resonances, the nanoparticle size, the chain length and the peak laser power, enabling nanometre-scale tuning of the optical and conducting properties of such nanomaterials. PMID:25065385

  15. Development of a quantitative assay to measure expression of transforming growth factor ß (TGF-ß) in Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) and evaluation of potential pitfalls in use with field-collected samples

    USGS Publications Warehouse

    Robertson, Laura S.; Ottinger, Christopher A.; Burdick, Summer M.; VanderKooi, Scott P.

    2012-01-01

    The Nature Conservancy is in the process of restoring the Williamson River Delta in an attempt to recreate important juvenile habitat for the endangered shortnose sucker Chasmistes brevirostris and the endangered Lost River sucker Deltistes luxatus. Measurement of TGF-β mRNA expression level was one of the indicators chosen to evaluate juvenile sucker health during the restoration process. TGF-β mRNA expression level has been correlated with disease status in several laboratory studies and TGF-β mRNA expression level has been used as a species-specific indicator of immune status in field-based fish health assessments. We describe here the identification of TGF-β and a possible splice variant from shortnose sucker and from Lost River sucker. The performance of a quantitative RT-PCR assay to measure TGF-β mRNA expression level was evaluated in field-collected spleen and kidney tissue samples. The quality of extracted RNA was higher in tissues harvested in September compared to July and higher in tissues harvested at lower temperature compared to higher temperature. In addition, the expression level of both TGF-β and 18S as assessed by qRT-PCR was higher in samples with higher quality RNA. TGF-β mRNA expression was lower in kidney than in spleen in both Lost River sucker and shortnose sucker.

  16. Rod Climbing of Suspensions

    NASA Astrophysics Data System (ADS)

    Guo, Youjing; Wang, Xiaorong

    We wish to report an unexpected effect observed for particle suspensions sucked to pass through a vertical pipe. Above a critical concentration, the suspension on the outside of the pipe may climb along the outside wall of the pipe and then display a surprising rod-climbing effect. Our study shows that the phenomenon is influenced mainly by the suspension composition, the pipe dimension and the suction speed. The effects of the pipe materials of different kinds are negligible. Increasing the suction force and the concentration increases the climbing height. Increasing the pipe diameter and wall thickness reduces the climbing effect. This behavior may be relevant to that the suspensions of the type described are all displaying markedly shear-thickening.

  17. Collisions of strings with Y junctions.

    PubMed

    Copeland, E J; Kibble, T W B; Steer, D A

    2006-07-14

    We study the dynamics of Nambu-Goto strings with junctions at which three strings meet. In particular, we exhibit one simple exact solution and examine the process of intercommuting of two straight strings in which they exchange partners but become joined by a third string. We show that there are important kinematical constraints on this process. The exchange cannot occur if the strings meet with very large relative velocity. This may have important implications for the evolution of cosmic superstring networks and non-Abelian string networks. PMID:16907431

  18. Cosmic String Global Superconducting Dirac Born Infeld

    NASA Astrophysics Data System (ADS)

    Ikrima, Ika; Ramadhan, Handhika S.; Mart, Terry

    2016-08-01

    Superconducting cosmic string possibly plays an important role in the formation of the universe structure. The physics of this phenomenon has been explored by studying the field theory in the string interior. Numerical solutions of superconducting strings with all relevant fields are presented in this paper. The field is constructed from a generalization of the usual field theory of superconducting global string, but the kinetic term consists of the Dirac Born Infeld (DBI). Some changes in the characteristic of the superconducting string DBI from the usual superconducting string case have been observed. The observation includes physical mechanism of all related fields.

  19. Sperm quality assessments for endangered razorback suckers Xyrauchen Texanus

    USGS Publications Warehouse

    Jenkins, Jill A.; Eilts, Bruce E.; Guitreau, Amy M.; Figiel, Chester R.; Draugelis-Dale, Rassa O.; Tiersch, Terrence R.

    2011-01-01

    Flow cytometry (FCM) and computer-assisted sperm motion analysis (CASA) methods were developed and validated for use with endangered razorback suckers Xyrauchen texanus collected (n=64) during the 2006 spawning season. Sperm motility could be activated within osmolality ranges noted during milt collections (here 167–343 mOsm/kg). We hypothesized that sperm quality of milt collected into isoosmotic (302 mOsm/kg) or hyperosmotic (500 mOsm/kg) Hanks' balanced salt solution would not differ. Pre-freeze viabilities were similar between osmolalities (79%±6 (S.E.M.) and 76%±7); however, post-thaw values were greater in hyperosmotic buffer (27%±3 and 12%±2; P=0.0065), as was mitochondrial membrane potential (33%±4 and 13%±2; P=0.0048). Visual estimates of pre-freeze motility correlated with total (r=0.7589; range 23–82%) and progressive motility (r=0.7449) by CASA and were associated with greater viability (r=0.5985; Pr=-0.83; P=0.0116) and mitochondrial function (r=-0.91; P=0.0016). By FCM-based assessments of DNA integrity, whereby increased fluorochrome binding indicated more fragmentation, higher levels were negatively correlated with count (r=-0.77; Pr=-0.66; P=0.0004). Fragmentation was higher in isotonic buffer (P=0.0234). To increase reproductive capacity of natural populations, the strategy and protocols developed can serve as a template for use with other imperiled fish species, biomonitoring, and genome banking.

  20. Generating string solutions in BTZ

    NASA Astrophysics Data System (ADS)

    David, Justin R.; Kalousios, Chrysostomos; Sadhukhan, Abhishake

    2013-02-01

    Integrability of classical strings in the BTZ black hole enables the construction and study of classical string propagation in this background. We first apply the dressing method to obtain classical string solutions in the BTZ black hole. We dress time like geodesics in the BTZ black hole and obtain open string solutions which are pinned on the boundary at a single point and whose end points move on time like geodesics. These strings upon regularising their charge and spins have a dispersion relation similar to that of giant magnons. We then dress space like geodesics which start and end on the boundary of the BTZ black hole and obtain minimal surfaces which can penetrate the horizon of the black hole while being pinned at the boundary. Finally we embed the giant gluon solutions in the BTZ background in two different ways. They can be embedded as a spiral which contracts and expands touching the horizon or a spike which originates from the boundary and touches the horizon.

  1. Rod gripper, changer, and storage system

    NASA Technical Reports Server (NTRS)

    Benson, Mark; Demi, Todd; Mcneill, Robert; Waldo, Keith; Afghan, Alex; Oliver, Jim

    1989-01-01

    A rod changer and storage design is presented for the lunar deep drill apparatus to be used in conjunction with the Skitter walking platform. The design must take into account all of the lunar environment and working conditions. Some of these are: (1) the moon has one sixth the gravity of earth; (2) temperature gradients can range from about -170 to 265 C; (3) because of the high transportation costs, the design must be as light as possible; and (4) the process must be remotely operated (from earth or satellite) and must be automated. Because of Skitter's multiple degree of freedom movement, the design will utilize Skitter's movement to locate an implement and transport it from the rack to the drill string. The implement will be gripped by a thumb and two finger device, identified through an electronic sensing device on the thumb, and transported from the rack to the footplate and back from the footplate to the rack. The major designs discussed in this report have been broken down into three major areas: (1) gripper design (linear transport mechanism); (2) indexing system; and (3) rack design.

  2. Constraints on string networks with junctions

    SciTech Connect

    Copeland, E. J.; Kibble, T. W. B.; Steer, D. A.

    2007-03-15

    We consider the constraints on string networks with junctions in which the strings may all be different, as may be found, for example, in a network of (p,q) cosmic superstrings. We concentrate on three aspects of junction dynamics. First we consider the propagation of small-amplitude waves across a static three-string junction. Then, generalizing our earlier work, we determine the kinematic constraints on two colliding strings with different tensions. As before, the important conclusion is that strings do not always reconnect with a third string; they can pass straight through one another (or in the case of non-Abelian strings become stuck in an X configuration), the constraint depending on the angle at which the strings meet, on their relative velocity, and on the ratios of the string tensions. For example, if the two colliding strings have equal tensions, then for ultrarelativistic initial velocities they pass through one another. However, if their tensions are sufficiently different they can reconnect. Finally, we consider the global properties of junctions and strings in a network. Assuming that, in a network, the incoming waves at a junction are independently randomly distributed, we determine the root-mean-square (r.m.s.) velocities of strings and calculate the average speed at which a junction moves along each of the three strings from which it is formed. Our findings suggest that junction dynamics may be such as to preferentially remove the heavy strings from the network leaving a network of predominantly light strings. Furthermore the r.m.s. velocity of strings in a network with junctions is smaller than 1/{radical}(2), the result for conventional Nambu-Goto strings without junctions in Minkowski space-time.

  3. Cosmic strings from supersymmetric flat directions

    SciTech Connect

    Cui Yanou; Morrissey, David E.; Martin, Stephen P.; Wells, James D.

    2008-02-15

    Flat directions are a generic feature of the scalar potential in supersymmetric gauge field theories. They can arise, for example, from D-terms associated with an extra Abelian gauge symmetry. Even when supersymmetry is broken softly, there often remain directions in the scalar field space along which the potential is almost flat. Upon breaking a gauge symmetry along one of these almost-flat directions, cosmic strings may form. Relative to the standard cosmic string picture based on the Abelian Higgs model, these flat-direction cosmic strings have the extreme type-I properties of a thin gauge core surrounded by a much wider scalar field profile. We perform a comprehensive study of the microscopic, macroscopic, and observational characteristics of this class of strings. We find many differences from the standard string scenario, including stable higher winding-mode strings, the dynamical formation of higher mode strings from lower ones, and a resultant multitension scaling string network in the early universe. These strings are only moderately constrained by current observations, and their gravitational wave signatures may be detectable at future gravity wave detectors. Furthermore, there is the interesting but speculative prospect that the decays of cosmic string loops in the early universe could be a source of ultrahigh-energy cosmic rays or nonthermal dark matter. We also compare the observational signatures of flat-direction cosmic strings with those of ordinary cosmic strings as well as (p,q) cosmic strings motivated by superstring theory.

  4. Cooperative strings and glassy interfaces.

    PubMed

    Salez, Thomas; Salez, Justin; Dalnoki-Veress, Kari; Raphaël, Elie; Forrest, James A

    2015-07-01

    We introduce a minimal theory of glass formation based on the ideas of molecular crowding and resultant string-like cooperative rearrangement, and address the effects of free interfaces. In the bulk case, we obtain a scaling expression for the number of particles taking part in cooperative strings, and we recover the Adam-Gibbs description of glassy dynamics. Then, by including thermal dilatation, the Vogel-Fulcher-Tammann relation is derived. Moreover, the random and string-like characters of the cooperative rearrangement allow us to predict a temperature-dependent expression for the cooperative length ξ of bulk relaxation. Finally, we explore the influence of sample boundaries when the system size becomes comparable to ξ. The theory is in agreement with measurements of the glass-transition temperature of thin polymer films, and allows quantification of the temperature-dependent thickness hm of the interfacial mobile layer. PMID:26100908

  5. Ambitwistor Strings in Four Dimensions

    NASA Astrophysics Data System (ADS)

    Geyer, Yvonne; Lipstein, Arthur E.; Mason, Lionel

    2014-08-01

    We develop ambitwistor string theories for four dimensions to obtain new formulas for tree-level gauge and gravity amplitudes with arbitrary amounts of supersymmetry. Ambitwistor space is the space of complex null geodesics in complexified Minkowski space, and in contrast to earlier ambitwistor strings, we use twistors rather than vectors to represent this space. Although superficially similar to the original twistor string theories of Witten, Berkovits, and Skinner, these theories differ in the assignment of world sheet spins of the fields, rely on both twistor and dual twistor representatives for the vertex operators, and use the ambitwistor procedure for calculating correlation functions. Our models are much more flexible, no longer requiring maximal supersymmetry, and the resulting formulas for amplitudes are simpler, having substantially reduced moduli. These are supported on the solutions to the scattering equations refined according to helicity and can be checked by comparison with corresponding formulas of Witten and of Cachazo and Skinner.

  6. Cooperative strings and glassy interfaces.

    PubMed

    Salez, Thomas; Salez, Justin; Dalnoki-Veress, Kari; Raphaël, Elie; Forrest, James A

    2015-07-01

    We introduce a minimal theory of glass formation based on the ideas of molecular crowding and resultant string-like cooperative rearrangement, and address the effects of free interfaces. In the bulk case, we obtain a scaling expression for the number of particles taking part in cooperative strings, and we recover the Adam-Gibbs description of glassy dynamics. Then, by including thermal dilatation, the Vogel-Fulcher-Tammann relation is derived. Moreover, the random and string-like characters of the cooperative rearrangement allow us to predict a temperature-dependent expression for the cooperative length ξ of bulk relaxation. Finally, we explore the influence of sample boundaries when the system size becomes comparable to ξ. The theory is in agreement with measurements of the glass-transition temperature of thin polymer films, and allows quantification of the temperature-dependent thickness hm of the interfacial mobile layer.

  7. Regenerative hyperpolarization in rods.

    PubMed Central

    Werblin, F S

    1975-01-01

    1. The electrical properties of the rods in Necturus maculosus were studied at the cell body and the outer segments in dark and light under current and voltage clamp with a pair of intracellular electrodes separated by about 1 mum. 2. The membrane resistance in the dark was voltage- and time-dependent both for the cell body and the outer segment. Slight depolarizations in the cell body reduced the slope resistance from 60 to 10 M omega with a time constant of about 1 sec. Polarization in either direction, at the outer segment, when greater than about 20 mV, reduced the slope resistance from 60 to 30 M omega. The dark potential in the cell body was typically -30 to -35 m V; at the outer segment it was typically only -10 to -15 mV. 3. The light-elicited voltage response in both the cell body and the outer segment was largest with the membrane near the dark potential level. In both regions, the response was reduced when the membrane was polarized in either direction. 4. Under voltage-clamp conditions, a reversal potential for the light response near + 10 mV was measured at the outer segment. At the cell body no reversal potential for the light response was measured; there the clamping current required during the light response was almost of the same magnitude at all potential levels. 5. When the membrane at the cell body was hyperpolarized in the dark under voltage clamp, a transient outward current, typically about one-half the magnitude of the initial inward clamping current was required to maintain the membrane at the clamped potential level. This outward current transient was associated with a decrease in membrane resistance with similar time course. The transient outward current reversed and became inward when the membrane was clamped to potentials more negative than -80 mV. Thus, the transient outward current appears to involve a transient activation initiated by hyperpolarization. I is regenerative in that it is initiated by hyperpolarization and tends to

  8. 75 FR 77961 - Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for Santa Ana Sucker

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-14

    ... Santa Ana sucker in this final rule. In the proposed rule (74 FR 65056; December 9, 2009) and the document that made available the draft economic analysis (DEA) (75 FR 38441; July 2, 2010), we stated that... River that we did not discuss in the 2005 final critical habitat designation for this species (70 FR...

  9. 29 CFR 1919.81 - Examination of bulk cargo loading or discharging spouts or suckers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Examination of bulk cargo loading or discharging spouts or suckers. 1919.81 Section 1919.81 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) GEAR CERTIFICATION Certification of...

  10. Tumours in white suckers from Lake Michigan tributaries: pathology and prevalence

    USGS Publications Warehouse

    Blazer, Vicki; Walsh, H.L.; Braham, R.P.; Hahn, C. M.; Mazik, P.; McIntyre, P.B.

    2016-01-01

    The prevalence and histopathology of neoplastic lesions were assessed in white suckerCatostomus commersonii captured at two Lake Michigan Areas of Concern (AOCs), the Sheboygan River and Milwaukee Estuary. Findings were compared to those observed at two non-AOC sites, the Root and Kewaunee rivers. At each site, approximately 200 adult suckers were collected during their spawning migration. Raised skin lesions were observed at all sites and included discrete white spots, mucoid plaques on the body surface and fins and large papillomatous lesions on lips and body. Microscopically, hyperplasia, papilloma and squamous cell carcinoma were documented. Liver neoplasms were also observed at all sites and included both hepatocellular and biliary tumours. Based on land use, the Kewaunee River was the site least impacted by human activities previously associated with fish tumours and had significantly fewer liver neoplasms when compared to the other sites. The proportion of white suckers with liver tumours followed the same patterns as the proportion of urban land use in the watershed: the Milwaukee Estuary had the highest prevalence, followed by the Root, Sheboygan and Kewaunee rivers. The overall skin neoplasm (papilloma and carcinoma) prevalence did not follow the same pattern, although the percentage of white suckers with squamous cell carcinoma exhibited a similar relationship to land use. Testicular tumours (seminoma) were observed at both AOC sites but not at the non-AOC sites. Both skin and liver tumours were significantly and positively associated with age but not sex.

  11. EXPLOITATION OF FLOODPLAIN RESOURCES BY ADULT LARGESCALE SUCKER OF THE WILLAMETTE RIVER, OREGON

    EPA Science Inventory

    We tested two predictions of the flood-pulse concept on a large, temperate alluvial river that historically flooded an extensive fringing floodplain. We predicted adult largescale sucker, Catostomus macrocheilus, would: (1) migrate onto the floodplain during high water; and (2) e...

  12. Genetic response of a white sucker population to experimental whole lake acidification

    EPA Science Inventory

    Background/Question/MethodsLake acidification can strongly impact the structure and function of lake ecosystems, causing extirpation of some species while other organisms are able adapt to changing pH. We followed the genetics of a population of white sucker (Catostomus commerso...

  13. Preliminary testing of the role of exercise and predator recognition for bonytail and razorback sucker

    USGS Publications Warehouse

    Mueller, Gordon A.; Carpenter, Jeanette; Krapfel, Robert; Figiel, Chester

    2007-01-01

    Razorback suckers exercised (treatment) in water current (<0.3 m/s) for 10 weeks exhibited greater swimming stamina than unexercised, control fish. When exercised and unexercised razorback suckers were placed together with large predators in 2006, treatment fish had significantly fewer (n = 9, z = 1.69, p = 0.046) mortalities than control fish, suggesting increased stamina improved predator escape skills. Predator/prey tests comparing razorback suckers that had been previously exposed to a predation event with control fish, found treatment fish also had significantly fewer losses than predatornaïve fish (p = 0.017). Similar tests exposing predator-savvy and predator-naïve bonytail with largemouth bass showed a similar trend; predator-savvy bonytail suffered 38 percent fewer losses than control fish. However, there was not a statistically significant difference between the test groups (p = 0.143) due to small sample size. All exercise and predator exposure trials increased the survival rate of razorback sucker and bonytail compared to untreated counterparts.

  14. Underwater attachment using hairs: the functioning of spatula and sucker setae from male diving beetles.

    PubMed

    Chen, Ying; Shih, Ming-Chih; Wu, Ming-Huang; Yang, En-Cheng; Chi, Kai-Jung

    2014-08-01

    Males of Dytiscinae beetles use specialized adhesive setae to adhere to female elytra during underwater courtship. This coevolution of male setae and female elytra has attracted much attention since Darwin. However, there has been little examination of their biomechanical functioning despite increasing knowledge on biofibrillar adhesion. Here, we report and compare, for the first time, the mechanisms of underwater attachment using two hair types, the primitive spatula and derived 'passive' sucker, found in male diving beetles. Results from interspecific scaling of protarsal palettes and adhesion by single seta suggest better performance in the later-evolved circular (sucker) setae. Spatula setae with a modified shallow sucker and channels use the combined mechanisms of suction and viscous resistance for adhesion. Velocity-dependent adhesion provides sufficient control for resisting the female's erratic movements while also detaching easily through slow peeling. Direction-dependent shear resistance helps reorient setae surfaces into a preferred direction for effective adhesion. Seta deformation using different mechanisms for circular and spatula setae reduces the force that is transmitted to the contact interface. A softer spring in spatula setae explains their adhesion at lower preloads and assists in complete substrate contact. Attachment mechanisms revealed in adhesive setae with modified spatula and passive suckers provide insights for bioinspired designs of underwater attachment devices.

  15. Underwater attachment using hairs: the functioning of spatula and sucker setae from male diving beetles

    PubMed Central

    Chen, Ying; Shih, Ming-Chih; Wu, Ming-Huang; Yang, En-Cheng; Chi, Kai-Jung

    2014-01-01

    Males of Dytiscinae beetles use specialized adhesive setae to adhere to female elytra during underwater courtship. This coevolution of male setae and female elytra has attracted much attention since Darwin. However, there has been little examination of their biomechanical functioning despite increasing knowledge on biofibrillar adhesion. Here, we report and compare, for the first time, the mechanisms of underwater attachment using two hair types, the primitive spatula and derived ‘passive’ sucker, found in male diving beetles. Results from interspecific scaling of protarsal palettes and adhesion by single seta suggest better performance in the later-evolved circular (sucker) setae. Spatula setae with a modified shallow sucker and channels use the combined mechanisms of suction and viscous resistance for adhesion. Velocity-dependent adhesion provides sufficient control for resisting the female's erratic movements while also detaching easily through slow peeling. Direction-dependent shear resistance helps reorient setae surfaces into a preferred direction for effective adhesion. Seta deformation using different mechanisms for circular and spatula setae reduces the force that is transmitted to the contact interface. A softer spring in spatula setae explains their adhesion at lower preloads and assists in complete substrate contact. Attachment mechanisms revealed in adhesive setae with modified spatula and passive suckers provide insights for bioinspired designs of underwater attachment devices. PMID:24920108

  16. Acoustic data transmission through a drill string

    DOEpatents

    Drumheller, D.S.

    1988-04-21

    Acoustical signals are transmitted through a drill string by canceling upward moving acoustical noise and by preconditioning the data in recognition of the comb filter impedance characteristics of the drill string. 5 figs.

  17. False beats in coupled piano string unisons

    NASA Astrophysics Data System (ADS)

    Capleton, Brian

    2004-02-01

    The behavior of a unison pair of piano strings coupled by the soundboard bridge, when one string has localized anisotropy in the reactive part of the bridge admittance for a given partial frequency, can be investigated using a theoretical matrix description. The anisotropy can cause what in piano tuning terminology is referred to as ``false beating'' in a partial of the single string. A mathematical model can be used to illustrate how ``mistunings'' between the strings of the unison (measured when the strings are sounding in isolation from each other) may theoretically arise as a consequence of the normal practice in piano tuning, of eliminating or reducing audible beating in the unison when both strings are sounding. ``False beats'' in a single string partial can be ``inherited'' by a partial of the coupled unison's spectrum, and mistunings between the strings can eliminate or reduce the appearance of this inheritance.

  18. False beats in coupled piano string unisons.

    PubMed

    Capleton, Brian

    2004-02-01

    The behavior of a unison pair of piano strings coupled by the soundboard bridge, when one string has localized anisotropy in the reactive part of the bridge admittance for a given partial frequency, can be investigated using a theoretical matrix description. The anisotropy can cause what in piano tuning terminology is referred to as "false beating" in a partial of the single string. A mathematical model can be used to illustrate how "mistunings" between the strings of the unison (measured when the strings are sounding in isolation from each other) may theoretically arise as a consequence of the normal practice in piano tuning, of eliminating or reducing audible beating in the unison when both strings are sounding. "False beats" in a single string partial can be "inherited" by a partial of the coupled unison's spectrum, and mistunings between the strings can eliminate or reduce the appearance of this inheritance. PMID:15000199

  19. String spectra near some null cosmological singularities

    SciTech Connect

    Madhu, Kallingalthodi; Narayan, K.

    2009-06-15

    We construct cosmological spacetimes with null Kasner-like singularities as purely gravitational solutions with no other background fields turned on. These can be recast as anisotropic plane-wave spacetimes by coordinate transformations. We analyze string quantization to find the spectrum of string modes in these backgrounds. The classical string modes can be solved for exactly in these time-dependent backgrounds, which enables a detailed study of the near-singularity string spectrum, (time-dependent) oscillator masses, and wave functions. We find that for low-lying string modes (finite oscillation number), the classical near-singularity string mode functions are nondivergent for various families of singularities. Furthermore, for any infinitesimal regularization of the vicinity of the singularity, we find a tower of string modes of ultrahigh oscillation number which propagate essentially freely in the background. The resulting picture suggests that string interactions are non-negligible near the singularity.

  20. Cosmic rays from cosmic strings with condensates

    SciTech Connect

    Vachaspati, Tanmay

    2010-02-15

    We revisit the production of cosmic rays by cusps on cosmic strings. If a scalar field ('Higgs') has a linear interaction with the string world sheet, such as would occur if there is a bosonic condensate on the string, cusps on string loops emit narrow beams of very high energy Higgses which then decay to give a flux of ultrahigh energy cosmic rays. The ultrahigh energy flux and the gamma to proton ratio agree with observations if the string scale is {approx}10{sup 13} GeV. The diffuse gamma ray and proton fluxes are well below current bounds. Strings that are lighter and have linear interactions with scalars produce an excess of direct and diffuse cosmic rays and are ruled out by observations, while heavier strings ({approx}10{sup 15} GeV) are constrained by their gravitational signatures. This leaves a narrow window of parameter space for the existence of cosmic strings with bosonic condensates.

  1. Metastable cosmic strings in realistic models

    SciTech Connect

    Holman, R.; Hsu, S.; Vachaspati, T.; Watkins, R. |

    1992-11-01

    The stability of the electroweak Z-string is investigated at high temperatures. The results show that, while finite temperature corrections can improve the stability of the Z-string, their effect is not strong enough to stabilize the Z-string in the standard electroweak model. Consequently, the Z-string will be unstable even under the conditions present during the electroweak phase transition. Phenomenologically viable models based on the gauge group SU(2){sub L} {times} SU(2) {sub R} {times} U(1){sub B-L} are then considered, and it is shown that metastable strings exist and are stable to small perturbations for a large region of the parameter space for these models. It is also shown that these strings are superconducting with bosonic charge carriers. The string superconductivity may be able to stabilize segments and loops against dynamical contraction. Possible implications of these strings for cosmology are discussed.

  2. Metastable cosmic strings in realistic models

    SciTech Connect

    Holman, R. . Dept. of Physics); Hsu, S. . Lyman Lab. of Physics); Vachaspati, T. . Dept. of Physics and Astronomy); Watkins, R. Fermi National Accelerator Lab., Batavia, IL )

    1992-01-01

    The stability of the electroweak Z-string is investigated at high temperatures. The results show that, while finite temperature corrections can improve the stability of the Z-string, their effect is not strong enough to stabilize the Z-string in the standard electroweak model. Consequently, the Z-string will be unstable even under the conditions present during the electroweak phase transition. Phenomenologically viable models based on the gauge group SU(2)[sub L] [times] SU(2) [sub R] [times] U(1)[sub B-L] are then considered, and it is shown that metastable strings exist and are stable to small perturbations for a large region of the parameter space for these models. It is also shown that these strings are superconducting with bosonic charge carriers. The string superconductivity may be able to stabilize segments and loops against dynamical contraction. Possible implications of these strings for cosmology are discussed.

  3. Energy and Momentum Transport in String Waves

    ERIC Educational Resources Information Center

    Juenker, D. W.

    1976-01-01

    Formulas are derived for the energy, momentum, and angular momentum transmitted by waves of arbitrary shape in an inextensible string by pure transverse waves in a string using Tait's procedure. (Author/CP)

  4. Eulerian formulation of elastic rods

    NASA Astrophysics Data System (ADS)

    Huynen, Alexandre; Detournay, Emmanuel; Denoël, Vincent

    2016-06-01

    In numerous biological, medical and engineering applications, elastic rods are constrained to deform inside or around tube-like surfaces. To solve efficiently this class of problems, the equations governing the deflection of elastic rods are reformulated within the Eulerian framework of this generic tubular constraint defined as a perfectly stiff normal ringed surface. This reformulation hinges on describing the rod-deformed configuration by means of its relative position with respect to a reference curve, defined as the axis or spine curve of the constraint, and on restating the rod local equilibrium in terms of the curvilinear coordinate parametrizing this curve. Associated with a segmentation strategy, which partitions the global problem into a sequence of rod segments either in continuous contact with the constraint or free of contact (except for their extremities), this re-parametrization not only trivializes the detection of new contacts but also transforms these free boundary problems into classic two-points boundary-value problems and suppresses the isoperimetric constraints resulting from the imposition of the rod position at the extremities of each rod segment.

  5. Temporal and spatial distribution of endangered juvenile Lost River and shortnose suckers in relation to environmental variables in Upper Klamath Lake, Oregon: 2009 annual data summary

    USGS Publications Warehouse

    Bottcher, Jared L.; Burdick, Summer M.

    2010-01-01

    Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were listed as endangered in 1988 for a variety of reasons including apparent recruitment failure. Upper Klamath Lake, Oregon, and its tributaries are considered the most critical remaining habitat for these two species. Age-0 suckers are often abundant in Upper Klamath Lake throughout the summer months, but catches decline dramatically between late August and early September each year. Similar declines of age-1 suckers between spring and late summer also occur annually. These rapid declines in catch rates and a lack of substantial recruitment into adult sucker populations in recent years suggests sucker populations experience high mortality between their first summer and first spawn. Summer age-0 sucker habitat use and distribution have been studied extensively, but many uncertainties remain about age-1 and older juvenile habitat use, distribution, and movement patterns within Upper Klamath Lake. This study was designed to examine seasonal changes in distribution of age-1 suckers in Upper Klamath Lake as they relate to depth and water quality. The results of our third annual spring and summer sampling effort are presented in this report. Catch data collected in 2009 indicate seasonal changes in age-1 and older juvenile sucker habitat use coincident with changes in water quality. Although age-1 sucker catch rates were again concentrated along the western shore in June and early July, as they were in 2007 and 2008, very few age-1 suckers were captured in Eagle Ridge Trench in 2009 - a deepwater area along the western shore extending from Howard Bay to Eagle Ridge Point. Instead, suckers in 2009 were concentrated in the relatively shallow bays along the western shore. Nevertheless, as dissolved-oxygen concentrations decreased in mid-July below sublethal thresholds around the Eagle Ridge Trench, age-1 suckers apparently moved away from the western shore, and subsequently were captured

  6. Smooth metrics for snapping strings

    NASA Astrophysics Data System (ADS)

    Gregory, Ruth; Hindmarsh, Mark

    1995-11-01

    We construct two possible metrics for Abelian Higgs vortices with ends on black holes. We show how the detail of the vortex fields smooths out the nodal singularities which exist in the idealized metrics. A corollary is that apparently topologically stable strings might be able to split by black hole pair production. We estimate the rate per unit length by reference to related Ernst and C-metric instantons, concluding that it is completely negligible for GUT-scale strings. The estimated rate for macroscopic superstrings is much higher, although still extremely small, unless there is an early phase of strong coupling.

  7. String theory in electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Ambjørn, Jan; Makeenko, Yuri M.; Semenoff, Gordon W.; Szabo, Richard J.

    2003-02-01

    A review of various aspects of superstrings in background electromagnetic fields is presented. Topics covered include the Born-Infeld action, spectrum of open strings in background gauge fields, the Schwinger mechanism, finite-temperature formalism and Hagedorn behaviour in external fields, Debye screening, D-brane scattering, thermodynamics of D-branes, and noncommutative field and string theories on D-branes. The electric field instabilities are emphasized throughout and contrasted with the case of magnetic fields. A new derivation of the velocity-dependent potential between moving D-branes is presented, as is a new result for the velocity corrections to the one-loop thermal effective potential.

  8. Semi-scaling cosmic strings

    SciTech Connect

    Vanchurin, Vitaly

    2010-11-01

    We develop a model of string dynamics with back-reaction from both scaling and non-scaling loops taken into account. The evolution of a string network is described by the distribution functions of coherence segments and kinks. We derive two non-linear equations which govern the evolution of the two distributions and solve them analytically in the limit of late times. We also show that the correlation function is an exponential, and solve the dynamics for the corresponding spectrum of scaling loops.

  9. Twenty-five questions for string theorists

    SciTech Connect

    Binetruy, Pierre; Kane, G.L.; Lykken, Joseph D.; Nelson, Brent D.; /Pennsylvania U.

    2005-09-01

    In an effort to promote communication between the formal and phenomenological branches of the high-energy theory community, we provide a description of some important issues in supersymmetric and string phenomenology. We describe each within the context of string constructions, illustrating them with specific examples where applicable. Each topic culminates in a set of questions that we believe are amenable to direct consideration by string theorists, and whose answers we think could help connect string theory and phenomenology.

  10. Study of Some Properties of Cosmic Strings.

    NASA Astrophysics Data System (ADS)

    Aryal, Mukunda Mani

    This work deals with some of the properties of stringlike topological structures that can arise in reasonable models of grand unified theories. We study stringlike structures formed when a simply or multiply connected group breaks spontaneously to an unbroken subgroup. If the original group is simply connected then the unbroken subgroup has to have two or more disconnected components in order to produce strings. If the number of such components of the unbroken subgroup is n, we call the resulting string Zn strings. In this work I want to study some properties of Z2 and Z3 strings. In some cases the unbroken subgroup Z2 can be embedded in different U(1) subgroups of G, giving topologically equivalent but dynamically different strings. We obtain the string mass in terms of the Higg's field vacuum expectation value of various values of the gauge and quartic Higg's field coupling constants by numerical calculation. We find that in a wide range of realistic cases the lowest mass embedding gives strings which are gauge equivalent to antistrings, in which case solitons of Hindmarsh and Kibble do not occur. Statistical properties of Z2 and Z3 strings produced in a phase transition in the early universe are studied using a Monte Carlo simulation. For Z3 strings it is shown that the system is dominated by one infinite network of Brownian strings. We calculate the gravitational field of a global string and conclude that distinguishing a global string from a gauge string observationally appears difficult at best in case such strings actually exist in nature. Our calculation is in weak field approximation. We also calculate the gravitational field of a cosmic string passing through a Schwarzschild black hole. We consider the thermodynamics of such an object. It is shown that S = (1/4)A where S is the entropy and A is the horizon area. Finally we discuss some problems in string electrodynamics.

  11. The vacuum interaction of magnetic strings

    SciTech Connect

    Bordag, M. )

    1991-03-01

    The author investigates the interaction of two parallel magnetic strings which is due to the perturbation of the vacuum state of a scalar massive field. The Green function with one string is studied in detail and the influence of the second string is found in perturbation theory. The Casimir is expressed in terms of Bessel functions.

  12. Introduction to the theory of strings

    SciTech Connect

    Peskin, M.E.

    1985-10-01

    These lectures present, from an introductory perspective, some basic aspects of the quantum theory of strings. They treat (1) the kinematics, spectrum, and scattering amplitude of the bosonic string, (2) the spectrum and supersymmetry of Green-Schwarz superstring, and (3) the identification of the underlying gauge invariances of the string theory. 43 refs.

  13. Transverse structure of the QCD string

    SciTech Connect

    Meyer, Harvey B.

    2010-11-15

    The characterization of the transverse structure of the QCD string is discussed. We formulate a conjecture as to how the stress-energy tensor of the underlying gauge theory couples to the string degrees of freedom. A consequence of the conjecture is that the energy density and the longitudinal-stress operators measure the distribution of the transverse position of the string, to leading order in the string fluctuations, whereas the transverse-stress operator does not. We interpret recent numerical measurements of the transverse size of the confining string and show that the difference of the energy and longitudinal-stress operators is a particularly natural probe at next-to-leading order. Second, we derive the constraints imposed by open-closed string duality on the transverse structure of the string. We show that a total of three independent ''gravitational'' form factors characterize the transverse profile of the closed string, and obtain the interpretation of recent effective string theory calculations: the square radius of a closed string of length {beta} defined from the slope of its gravitational form factor, is given by (d-1/2{pi}{sigma})log({beta}/4r{sub 0}) in d space dimensions. This is to be compared with the well-known result that the width of the open string at midpoint grows as (d-1/2{pi}{sigma})log(r/r{sub 0}). We also obtain predictions for transition form factors among closed-string states.

  14. How Do String Majors Become Teachers?

    ERIC Educational Resources Information Center

    Ha, Joy

    2015-01-01

    This study was motivated by the desire to understand how to support the development of competent and confident string instrument teachers. This research investigates early-career string instrument teachers' experiences of pre-service tertiary education and induction, and how these experiences impacted early-career string teachers' competence to…

  15. The Physics of "String Passing through Ice"

    ERIC Educational Resources Information Center

    Mohazzabi, Pirooz

    2011-01-01

    One of the oldest yet interesting experiments related to heat and thermodynamics is placing a string on a block of ice and hanging two masses from the ends of the string. Sometime later, it is discovered that the string has passed through the ice without cutting it in half. A simple explanation of this effect is that the pressure caused by the…

  16. The Picture Brightens (Slightly) for String Programs

    ERIC Educational Resources Information Center

    Olson, Cathy Applefeld

    2010-01-01

    It may not be the best of times for the school's string and orchestra programs, but things certainly are looking up. This article focuses on a recent report which cites the numerous positives, including an increase in the number of districts offering strings classes, a greater variety in the racial mix of strings students, and a less drastic…

  17. Pathogenesis of skin and liver neoplasms in white suckers from industrially polluted areas in Lake Ontario.

    PubMed

    Hayes, M A; Smith, I R; Rushmore, T H; Crane, T L; Thorn, C; Kocal, T E; Ferguson, H W

    1990-05-01

    Increased prevalences of epidermal and hepatobiliary neoplasms in white suckers (Catostomu commersoni) and brown bullheads (Ictalurus nebulosus) in the Western region of Lake Ontario have been associated with industrial pollution, but the identity and causative role of environmental carcinogens have not yet been established. Most epidermal tumors of lip and body skin are benign focal proliferations that occur in fish from the polluted Hamilton region, and also in fish from less polluted sites in the Great Lakes. These skin tumors in white suckers do not have consistent alterations in cellular glutathione S-transferases (GST), suggesting that growth of skin tumors is not promoted by chemicals normally detoxified by GST. However, elevated levels of glutathione peroxidase (GPO) and glutathione reductase (GR) in skin papillomas are indicative of promotional peroxidative tissue injury, either caused directly by xenobiotics or indirectly by chemical-induced inflammation. Liver tumors in white suckers from Lake Ontario include preneoplastic, benign, and malignant populations of hepatocellular and biliary cells, all of which are more prevalent in fish from polluted sites. These liver tumors are consistently associated with chronic cholangiohepatitis and segmental cholangiofibrosis, but these conditions also occur in white suckers in non-industrial locations. Thus, the natural occurrence of biliary disease, not attributable to industrial pollution, may have some influence on the development of liver tumors. Some preneoplastic lesions and the majority of neoplastic hepatocellular and biliary lesions in white suckers have low levels of total GST, indicating that these liver neoplasms are not promoted by xenobiotics normally detoxified by hepatic GSTs.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2360036

  18. Energy in a String Wave

    NASA Astrophysics Data System (ADS)

    Ng, Chiu-king

    2010-01-01

    When one end of a taut horizontal elastic string is shaken repeatedly up and down, a transverse wave (assume sine waveform) will be produced and travel along it. College students know this type of wave motion well. They know when the wave passes by, each element of the string will perform an oscillating up-down motion, which in mechanics is termed simple harmonic2. They also know elements of the string at the highest and the lowest positions—the crests and the troughs—are momentarily at rest, while those at the centerline (zero displacement) have the greatest speed, as shown in Fig. 1. Irrespective of this, they are less familiar with the energy associated with the wave. They may fail to answer a question such as, "In a traveling string wave, which elements have respectively the greatest kinetic energy (KE) and the greatest potential energy (PE)?" The answer to the former is not difficult; elements at zero position have the fastest speed and hence their KE, being proportional to the square of speed, is the greatest. To the PE, what immediately comes to their mind may be the simple harmonic motion (SHM), in which the PE is the greatest and the KE is zero at the two turning points. It may thus lead them to think elements at crests or troughs have the greatest PE. Unfortunately, this association is wrong. Thinking that the crests or troughs have the greatest PE is a misconception.3

  19. String duality and black holes

    NASA Astrophysics Data System (ADS)

    Kalara, S.; Nanopoulos, D. V.

    1991-09-01

    In the context of (semi) classical general relativity, the physics of black holes poses many unanswered and unsettling questions. Notable among them are the loss of quantum coherence, which casts doubts on the basic foundations of quantum mechanics, and the understanding of the enormous entropy carried by black holes which is at odds with strong ``no hair'' theorems. We point out that in string theory, black-hole type solutions (S-black holes) carry local discrete charges inherited from the duality symmetries of the string, which allow S-black holes to carry ``quantum hair''. It is further noted that the conservation of the discrete charges and the presence of quantum hair precludes the information about a quantum state from being completely lost in the black hole thus rescuing quantum coherence. We also note that a large number of quantum hair carried by S-black holes may explain their enormous entropy, i.e. it is the duality symmetry of the string theory which redeems outstanding problems of black-hole dynamics. We also discuss a possible description of black holes as solitons of string theory. Supported in part by DOE Grant DE-AS05-81 ER40039.

  20. Coupled currents in cosmic strings

    SciTech Connect

    Lilley, Marc; Peter, Patrick; Martin, Xavier

    2009-05-15

    We examine the structure of a cosmic string endowed with two Abelian neutral currents, associated with two global U(1) symmetries. We first resolve the microstructure and show that it depends on two state parameters, namely, the squares of the phase gradients of the current carriers. We then provide a macroscopic description for such a string and show that it depends on an additional Lorentz-invariant state parameter that relates the two currents. We find that in most of the parameter space, the two-current string is essentially equivalent to the single-current-carrying string; i.e., only one field condenses onto the defect. In the regions where two currents are present, we find that as far as stability is concerned, one can approximate the dynamics with good accuracy using an analytic model based on either a logarithmic (on the electric side, i.e., for timelike currents) or a rational (on the magnetic side, i.e., for spacelike currents) world sheet Lagrangian. We end up by generalizing to the N current case.

  1. Localized gravity in string theory.

    PubMed

    Karch, A; Randall, L

    2001-08-01

    We propose a string realization of the AdS4 brane in AdS5 that is known to localize gravity. Our theory is M D5 branes in the near horizon geometry of N D3 branes, where M and N are appropriately tuned.

  2. String Physics at the LHC

    SciTech Connect

    Anchordoqui, Luis A.

    2008-11-23

    The LHC program will include the identification of events with single high-k{sub T} photons as probes of new physics. We show that this channel is uniquely suited to search for experimental evidence of TeV-scale open string theory.

  3. Transporting Solar-Cell Strings

    NASA Technical Reports Server (NTRS)

    Bycer, M.; Frasch, W.

    1982-01-01

    Vacuum "lance" picks up assembled chain of solar cells from string conveyor without disturbing cells or interconnecting tabs. Lance has 2 vacuum pickups per cell, for total of up to 32 pickups. Positions and number of pickups can be varied. Lance can be adjusted for range of cell sizes, shapes, and spacings.

  4. Accidental degeneracies in string compactification

    NASA Astrophysics Data System (ADS)

    Bais, F. A.; Taormina, A.

    1986-11-01

    The equivalence of the torus and group manifold compactification of strings is established. Accidental degeneracies are shown to occur for a large class of compactifications. This way many examples are obtained in which modular invariance does not uniquely fix the representation content of the spectrum.

  5. Computer Simulations of Coupled Piano Strings

    NASA Astrophysics Data System (ADS)

    Albert, Destiny L.

    1997-03-01

    The behavior of coupled piano strings is studied by using a finite difference scheme. The coupling of the strings produce motion in two transverse directions, parallel and perpendicular to the soundboard. The sound induced shows two decay rates, a rapid decay followed by a slow decay. These effects are in agreement with experimental results. (Weinreich, Gabriel. "The Coupled Motion of Piano Strings." Scientific American. January 1979) . Our simulations suggest that the motion of the end supports contributes to the elliptical motion of the strings. Furthermore, multiple strings contribute to the quality of the sound produced by a piano.

  6. Cosmic string scaling in flat space

    SciTech Connect

    Vanchurin, Vitaly; Olum, Ken; Vilenkin, Alexander

    2005-09-15

    We investigate the evolution of infinite strings as a part of a complete cosmic string network in flat space. We perform a simulation of the network which uses functional forms for the string position and thus is exact to the limits of computer arithmetic. Our results confirm that the wiggles on the strings obey a scaling law described by universal power spectrum. The average distance between long strings also scales accurately with the time. These results suggest that small-scale structure will also scale in an expanding universe, even in the absence of gravitational damping.

  7. D-term inflation without cosmic strings.

    PubMed

    Urrestilla, J; Achúcarro, A; Davis, A C

    2004-06-25

    We present a superstring-inspired version of D-term inflation that does not lead to cosmic string formation and appears to satisfy the current cosmic microwave background constraints. It differs from minimal D-term inflation by a second pair of charged superfields that makes the strings nontopological (semilocal). The strings are also Bogomol'nyi-Prasad-Sommerfield strings, so the scenario is expected to survive supergravity corrections. The second pair of charged superfields arises naturally in several brane and conifold scenarios, but its effect on cosmic string formation had not been noticed so far. PMID:15244993

  8. Are cosmic strings gravitationally stable topological defects?

    NASA Astrophysics Data System (ADS)

    Gleiser, Reinaldo; Pullin, Jorge

    1989-08-01

    A possible mechanism for the dissapearance of an open cosmic string into gravitational radiation is described. This involves the splitting of an infinite straight cosmic string into two pieces whose ends are traveling outward at the speed of light with the associated emission of a gravitational shock wave. This model can also be used to describe the following situations: (1) the development of a growing region of different string tension within a cosmic string, and (2) the creation of a cosmic string in an otherwise flat background.

  9. Growth and characterization of string ribbon

    SciTech Connect

    Hanoka, J.I.; Behnin, B.; Michel, J.; Symko, M.; Sopori, B.L.

    1995-08-01

    Evergreen Solar, a new photovoltaics company, makes solar cells and modules based on String Ribbon. String Ribbon is a silicon sheet growth method wherein two high temperature strings are pulled through a shallow melt of silicon and a crystalline silicon sheet then grows between the two strings. The strings serve to stabilize the edges of the growing silicon sheet. The growth process is primarily meniscus controlled and, compared to other silicon ribbon growth methods such as d-web and EFG, relatively insensitive to temperature fluctuations as great as {+-}10{degrees}C. Growth speed is about 2 cm/minute.

  10. Nuclear design of Helical Cruciform Fuel rods

    SciTech Connect

    Shirvan, K.; Kazimi, M. S.

    2012-07-01

    In order to increase the power density of current and new light water reactor designs, the Helical Cruciform Fuel (HCF) rods are proposed. The HCF rods are equivalent to a cylindrical rod, with the fuel in a cruciform shaped, twisted axially. The HCF rods increase the surface area to volume ratio and inter-subchannel mixing behavior due to their cruciform and helical shapes, respectively. In a previous study, the HCF rods have shown the potential to up-rate existing PWRs by 50% and BWRs by 25%. However, HCF rods do display different neutronics modeling and performance. The cruciform cross section of HCF rods creates radially asymmetric heat generation and temperature distribution. The nominal HCF rod's beginning of life reactivity is reduced, compared to a cylindrical rod with the same fuel volume, by 500 pcm, due to increase in absorption in cladding. The rotation of these rods accounts for reactivity changes, which depends on the H/HM ratio of the pin cell. The HCF geometry shows large sensitivities to U{sup 235} or gadolinium enrichments compared to a cylindrical geometry. In addition, the gadolinium-containing HCF rods show a stronger effect on neighboring HCF rods than in case of cylindrical rods, depending on the orientation of the HCF rods. The helical geometry of the rods introduces axial shadowing of about 600 pcm, not seen in typical cylindrical rods. (authors)

  11. CMB constraints on cosmic strings and superstrings

    NASA Astrophysics Data System (ADS)

    Charnock, Tom; Avgoustidis, Anastasios; Copeland, Edmund J.; Moss, Adam

    2016-06-01

    We present the first complete Markov chain Monte Carlo analysis of cosmological models with evolving cosmic (super)string networks, using the unconnected segment model in the unequal-time correlator formalism. For ordinary cosmic string networks, we derive joint constraints on Λ cold dark matter (CDM) and string network parameters, namely the string tension G μ , the loop-chopping efficiency cr, and the string wiggliness α . For cosmic superstrings, we obtain joint constraints on the fundamental string tension G μF, the string coupling gs, the self-interaction coefficient cs, and the volume of compact extra dimensions w . This constitutes the most comprehensive CMB analysis of Λ CDM cosmology+strings to date. For ordinary cosmic string networks our updated constraint on the string tension, obtained using Planck2015 temperature and polarization data, is G μ <1.1 ×10-7 in relativistic units, while for cosmic superstrings our constraint on the fundamental string tension after marginalizing over gs, cs, and w is G μF<2.8 ×10-8.

  12. String Theory and M-Theory

    NASA Astrophysics Data System (ADS)

    Becker, Katrin; Becker, Melanie; Schwarz, John H.

    String theory is one of the most exciting and challenging areas of modern theoretical physics. This book guides the reader from the basics of string theory to recent developments. It introduces the basics of perturbative string theory, world-sheet supersymmetry, space-time supersymmetry, conformal field theory and the heterotic string, before describing modern developments, including D-branes, string dualities and M-theory. It then covers string geometry and flux compactifications, applications to cosmology and particle physics, black holes in string theory and M-theory, and the microscopic origin of black-hole entropy. It concludes with Matrix theory, the AdS/CFT duality and its generalizations. This book is ideal for graduate students and researchers in modern string theory, and will make an excellent textbook for a one-year course on string theory. It contains over 120 exercises with solutions, and over 200 homework problems with solutions available on a password protected website for lecturers at www.cambridge.org/9780521860697. Comprehensive coverage of topics from basics of string theory to recent developments Ideal textbook for a one-year course in string theory Includes over 100 exercises with solutions Contains over 200 homework problems with solutions available to lecturers on-line

  13. Dynamical AdS strings across horizons

    DOE PAGES

    Ishii, Takaaki; Murata, Keiju

    2016-03-01

    We examine the nonlinear classical dynamics of a fundamental string in anti-deSitter spacetime. The string is dual to the flux tube between an external quark-antiquark pair in $N = 4$ super Yang-Mills theory. We perturb the string by shaking the endpoints and compute its time evolution numerically. We find that with sufficiently strong perturbations the string continues extending and plunges into the Poincare´ horizon. In the evolution, effective horizons are also dynamically created on the string worldsheet. The quark and antiquark are thus causally disconnected, and the string transitions to two straight strings. The forces acting on the endpoints vanishmore » with a power law whose slope depends on the perturbations. Lastly, the condition for this transition to occur is that energy injection exceeds the static energy between the quark-antiquark pair.« less

  14. New ways to look for cosmic strings

    NASA Astrophysics Data System (ADS)

    Beresnyak, Andrey

    2015-08-01

    Cosmic strings are linear topological defects which are hypothesized to be produced during inflation. Most searches for strings have been relying on the string's lensing of background galaxies or CMB. However, the interaction of the string with ordinary gas will produce several detectable signatures. I will explain how to obtain the solution for the supersonic flow of the collisional gas past the cosmic string. This solution has two planar shocks with shock compression ratio that depend on the angle defect of the string and its speed. These shocks compress and heat the gas, which should be detectable in high-z HI emission. Furthermore, in the present Universe, colliding with ionized rarefied HII gas, the string should produce particle acceleration at the shock and corresponding radio emission. The consequences of such collision will persist for cosmological timescales, so we should look for several unusual large-scale radio sources, typically a cluster radio halo size, situated on a single spatial plane.

  15. Dynamical AdS strings across horizons

    NASA Astrophysics Data System (ADS)

    Ishii, Takaaki; Murata, Keiju

    2016-03-01

    We examine the nonlinear classical dynamics of a fundamental string in anti-de Sitter spacetime. The string is dual to the flux tube between an external quark-antiquark pair in {N}=4 super Yang-Mills theory. We perturb the string by shaking the endpoints and compute its time evolution numerically. We find that with sufficiently strong perturbations the string continues extending and plunges into the Poincaré horizon. In the evolution, effective horizons are also dynamically created on the string worldsheet. The quark and antiquark are thus causally disconnected, and the string transitions to two straight strings. The forces acting on the endpoints vanish with a power law whose slope depends on the perturbations. The condition for this transition to occur is that energy injection exceeds the static energy between the quark-antiquark pair.

  16. String theory as a Lilliputian world

    NASA Astrophysics Data System (ADS)

    Ambjørn, J.; Makeenko, Y.

    2016-05-01

    Lattice regularizations of the bosonic string do not allow us to probe the tachyon. This has often been viewed as the reason why these theories have never managed to make any contact to standard continuum string theories when the dimension of spacetime is larger than two. We study the continuum string theory in large spacetime dimensions where simple mean field theory is reliable. By keeping carefully the cutoff we show that precisely the existence of a tachyon makes it possible to take a scaling limit which reproduces the lattice-string results. We compare this scaling limit with another scaling limit which reproduces standard continuum-string results. If the people working with lattice regularizations of string theories are akin to Gulliver they will view the standard string-world as a Lilliputian world no larger than a few lattice spacings.

  17. RP cone-rod degeneration.

    PubMed Central

    Heckenlively, J R

    1987-01-01

    A group of patients with progressive retinal degeneration and visual field loss, who meet the basic definition of RP were investigated to better define the relationship of the findings on the ERG with clinical characteristics such as visual field size, presence or absence of scotomata or pseudo-altitudinal defects on visual field, amount of night blindness; and presence or absence of macular or optic nerve changes. These studies suggest that cone-rod degeneration patients of the RP type go through the following stages; early, the ERG has a definite cone-rod pattern where the rod ERG is larger than the cone ERG while both are abnormal. As the disease advances, there is more of a reduction in the scotopic ERG such that both the rod and cone ERGs become nearly equal. As the disease further progresses the ERG becomes non-recordable on single-flash technique, but there is good residual rod function and the final rod threshold remains good until the visual field is reduced, typically less than 10 degrees with the IV-4 isopter. Finally with advanced disease the patient becomes night blind and generally becomes very difficult to distinguished from patients who have advanced rod-cone degeneration. While it may seem logical to find that visual field size correlates with various ERG parameters; this has not been as consistent a finding in patients with rod-cone degeneration in the author's experience. The analysis shows several new pieces of information about visual field changes in cone-rod degeneration; enlarged blind spots are seen earlier in cases which have recordable cone-rod patterns (group I), and pseudo-altitudinal changes are more likely to occur in autosomal recessive patients. Patients with macular lesions and central scotomata had larger amplitudes than patients with normal appearing maculae and no central scotomata. Patients with temporal optic atrophy had an earlier onset of symptoms and significant correlation with both photopic a- and b-waves and bright flash

  18. Apparatus and method for automatically and periodically introducing a fluid into a producing oil well

    SciTech Connect

    Soderberg, P.B.

    1987-07-21

    This patent describes a method for periodically and automatically introducing a fluid into a producing well through a tubing drain valve in a string of production tubing, comprising: disabling temporarily, automatically and at periodic time intervals a string of sucker rods disposed within the string of production tubing between a surface-located means for operating the sucker rods and a downhole pump so that a mechanical actuator on the string of sucker rods is stopped in a predetermined position on one side of a lever means of the tubing drain valve. An apparatus is described useful for periodically and automatically introducing a fluid into a producing well through a tubing drain valve located in a production string, comprising: a string of production tubing suitable for suspension in a producing well; surface and downhole pumps connected by a string of sucker rods for lifting well fluids through the production tubing; a tubing drain valve within the production string, the tubing drain valve actuated to its opened position by increased pressure within the production tubing and actuated to its closed position by movement of a lever means of the value; means in communication with the interior of the production tubing for pressurizing the production tubing to a pressure sufficient to open the tubing drain valve; means in communication with the interior of the production tubing for introducing a fluid into the production tubing; an actuator means disposed on the string of sucker rods for mechanically closing the tubing drain valve by cooperation with the lever means on the valve; and means for controlling automatically the operation of the above components at periodic time intervals for automatically conveying a fluid into the production tubing and through the tubing drain valve.

  19. Biological characteristics of the blue sucker in the James River and the Big Sioux River, South Dakota

    USGS Publications Warehouse

    Morey, N.M.; Berry, C.R.

    2003-01-01

    Little is known about the relative abundance and biology of the blue sucker (Cycleptus elongatus), a species that may be declining in some parts of its range. We described the age, growth, condition, length distribution, and habitat preference of the blue sucker in two South Dakota rivers. Specimens were collected from the James River (n=74) and Big Sioux River (n=28) during the summer of 2000. Although five macrohabitats were sampled with electrofishing and hoopnets, most individuals were collected from riffle habitats and downstream of rock dams. Total length-weight relationships were log10W=-6.14+3.37(log10L) (r2 = 0.92) for blue suckers from the James River and log10W = -6.52+3.50(log10L) (r2 = 0.97) for fish from the Big Sioux River. Mean condition factors (K = W(105)/L3) of blue suckers were 0.79 (SE = 0.07) for the James River and 0.73 (SE = 0.07) for the Big Sioux River. Blue suckers between 500 and 700 mm dominated length distributions (range = 374-717 mm) of both samples. Ages ranged from two to nine years, but six-year-old fish were captured most frequently. Blue suckers grew rapidly during juvenile stages (< age 5); however, growth slowed afterward.

  20. NEUTRONIC REACTOR CONTROL ROD DRIVE APPARATUS

    DOEpatents

    Oakes, L.C.; Walker, C.S.

    1959-12-15

    ABS>A suspension mechanism between a vertically movable nuclear reactor control rod and a rod extension, which also provides information for the operator or an automatic control signal, is described. A spring connects the rod extension to a drive shift. The extension of the spring indicates whether (1) the rod is at rest on the reactor, (2) the rod and extension are suspended, or (3) the extension alone is suspended, the spring controlling a 3-position electrical switch.

  1. Through tubing progressing cavity pump

    SciTech Connect

    Morgan, A.E.

    1986-06-03

    A method is described of installing a progressing cavity pump assembly within a well, the pump assembly being of the type having a stator, a helical rotor located in the stator and rotated by a string of sucker rods extending through tubing to the surface. The method consists of: securing a tubular seating member to a lower end of the tubing and lowering the tubing into the well; mounting a seating member on a lower end of the pump assembly; mounting a rotor nipple to the upper end of the stator and a drive rod to the upper end of the rotor, and providing the rotor nipple and drive rod with engaging means that allows a selected amount of vertical movement of the rotor with respect to the stator; connecting the upper end of the drive rod to the sucker rods; lowering the pump assembly into the tubing on the sucker rods until the seating member on the pump assembly contacts the tubular seating member; continuing to lower the sucker rods without rotation, moving the rotor downward with respect to the stator and forcing the seating members together with the weight of the sucker rods applied to the stator through the engaging means; then moving the sucker rods and the rotor a selected distance upward while the stator remains stationary to position the top of the rotor above the stator a selected distance; then connecting the sucker rods at the surface to a rotary power source and rotating the sucker rods to cause the pump to operate.

  2. Techniques for Monitoring Razorback Sucker in the Lower Colorado River, Hoover to Parker Dams, 2006-2007, Final Report

    USGS Publications Warehouse

    Mueller, Gordon A.; Wydoski, Richard; Best, Eric; Hiebert, Steve; Lantow, Jeff; Santee, Mark; Goettlicher, Bill; Millosovich, Joe

    2008-01-01

    Trammel netting is generally the accepted method of monitoring razorback sucker in reservoirs, but this method is ineffective for monitoring this fish in rivers. Trammel nets set in the current become fouled with debris, and nets set in backwaters capture high numbers of nontarget species. Nontargeted fish composed 97 percent of fish captured in previous studies (1999-2005). In 2005, discovery of a large spawning aggregation of razorback sucker in midchannel near Needles, Calif., prompted the development of more effective methods to monitor this and possibly other riverine fish populations. This study examined the effectiveness of four methods of monitoring razorback sucker in a riverine environment. Hoop netting, electrofishing, boat surveys, and aerial photography were evaluated in terms of data accuracy, costs, stress on targeted fish, and effect on nontargeted fish as compared with trammel netting. Trammel netting in the riverine portion of the Colorado River downstream of Davis Dam, Arizona-Nevada yielded an average of 43 razorback suckers a year (1999 to 2005). Capture rates averaged 0.5 razorback suckers per staff day effort, at a cost exceeding $1,100 per fish. Population estimates calculated for 2003-2005 were 3,570 (95 percent confidence limits [CL] = 1,306i??i??i??-8,925), 1,768 (CL = 878-3,867) and 1,652 (CL = 706-5,164); wide confidence ranges reflect the small sample size. By-catch associated with trammel netting included common carp, game fish and, occasionally, shorebirds, waterfowl, and muskrats. Hoop nets were prone to downstream drift owing to design and anchoring problems aggravated by hydropower ramping. Tests were dropped after the 2006 field season and replaced with electrofishing. Electrofishing at night during low flow and when spawning razorback suckers moved to the shoreline proved extremely effective. In 2006 and 2007, 263 and 299 (respectively) razorback suckers were taken. Capture rates averaged 8.3 razorback suckers per staff day at a

  3. Open strings on D-branes and Hagedorn regime in string gas cosmology

    SciTech Connect

    Arslanargin, Ayse; Kaya, Ali

    2009-03-15

    We consider early time cosmic evolution in string gas cosmology dominated by open strings attached to D-branes. After reviewing statistical properties of open strings in D-brane backgrounds, we use dilaton-gravity equations to determine the string frame fields. Although, there are distinctions in the Hagedorn regime thermodynamics and dilaton coupling as compared to closed strings, it seems difficult to avoid Jeans instability and assume thermal equilibrium simultaneously, which is already a known problem for closed strings. We also examine characteristics of a possible subsequent large radius regime in this setup.

  4. Health and condition of endangered juvenile Lost River and shortnose suckers relative to water quality and fish assemblages in Upper Klamath Lake, Oregon, and Clear Lake Reservoir, California

    USGS Publications Warehouse

    Burdick, Summer M.; Elliott, Diane G.; Ostberg, Carl O.; Conway, Carla M.; Dolan-Caret, Amari; Hoy, Marshal S.; Feltz, Kevin P.; Echols, Kathy R.

    2015-01-01

    Differences in sucker health and condition between lakes were considered the most promising clues to the causes of differential juvenile sucker morality between lakes. A low prevalence of petechial hemorrhaging of the skin (16 percent) and deformed opercula (8 percent) in Upper Klamath Lake suckers may indicate exposure to a toxin other than microcystin. Suckers grew slower in their first year of life, but had similar or greater triglyceride and glycogen levels in Upper Klamath Lake compared to Clear Lake Reservoir. These findings do not suggest a lack of prey quantity but may indicate lower prey quality in Upper Klamath Lake.

  5. Health and condition of endangered juvenile Lost River and shortnose suckers relative to water quality and fish assemblages in Upper Klamath Lake, Oregon, and Clear Lake Reservoir, California

    USGS Publications Warehouse

    Burdick, Summer M.; Elliott, Diane G.; Ostberg, Carl O.; Conway, Carla M.; Dolan-Caret, Amari; Hoy, Marshal S.; Feltz, Kevin P.; Echols, Kathy R.

    2015-11-25

    Differences in sucker health and condition between lakes were considered the most promising clues to the causes of differential juvenile sucker morality between lakes. A low prevalence of petechial hemorrhaging of the skin (16 percent) and deformed opercula (8 percent) in Upper Klamath Lake suckers may indicate exposure to a toxin other than microcystin. Suckers grew slower in their first year of life, but had similar or greater triglyceride and glycogen levels in Upper Klamath Lake compared to Clear Lake Reservoir. These findings do not suggest a lack of prey quantity but may indicate lower prey quality in Upper Klamath Lake.

  6. Gravitational waves and light cosmic strings

    NASA Astrophysics Data System (ADS)

    Depies, Matthew

    Gravitational wave signatures from cosmic strings are analyzed numerically. Cosmic string networks form during phase transistions in the early universe and these networks of long cosmic strings break into loops that radiate energy in the form of gravitational waves until they decay. The gravitational waves come in the form of harmonic modes from individual string loops, a "confusion noise" from galactic loops, and a stochastic background of gravitational waves from a network of loops. In this study string loops of larger size a and lower string tensions G m, (where m the mass per unit length of the string) are investigated than in previous studies. Several detectors are currently searching for gravitational waves and a space based satellite, the Laser Interferometer Space Antenna (LISA), is in the final stages of pre-flight. The results for large loop sizes (a = 0.1) put an upper limit of about G m < 10 -9 and indicate that gravitational waves from string loops down to G m [approximate] 10 -20 could be detectabe by LISA. The string tension is related to the energy scale of the phase transition and the Planck mass via Gm = [Special characters omitted.] , so the limits on G m set the energy scale of any phase transition L s < 10^-4.5 m pl . Our results indicate that loops may form a significant gravitational wave signal, even for string tensions too low to have larger cosmological effects.

  7. Orbifolds of M-strings

    NASA Astrophysics Data System (ADS)

    Haghighat, Babak; Kozçaz, Can; Lockhart, Guglielmo; Vafa, Cumrun

    2014-02-01

    We consider M theory in the presence of M parallel M5-branes probing a transverse AN -1 singularity. This leads to a superconformal theory with (1,0) supersymmetry in six dimensions. We compute the supersymmetric partition function of this theory on a two-torus, with arbitrary supersymmetry preserving twists, using the topological vertex formalism. Alternatively, we show that this can also be obtained by computing the elliptic genus of an orbifold of recently studied M-strings. The resulting two-dimensional theory is a (4,0) supersymmetric quiver gauge theory whose Higgs branch corresponds to strings propagating on the moduli space of SU(N)M -1 instantons on R4, where the right-moving fermions are coupled to a particular bundle.

  8. The fragment assembly string graph.

    PubMed

    Myers, Eugene W

    2005-09-01

    We present a concept and formalism, the string graph, which represents all that is inferable about a DNA sequence from a collection of shotgun sequencing reads collected from it. We give time and space efficient algorithms for constructing a string graph given the collection of overlaps between the reads and, in particular, present a novel linear expected time algorithm for transitive reduction in this context. The result demonstrates that the decomposition of reads into kmers employed in the de Bruijn graph approach described earlier is not essential, and exposes its close connection to the unitig approach we developed at Celera. This paper is a preliminary piece giving the basic algorithm and results that demonstrate the efficiency and scalability of the method. These ideas are being used to build a next-generation whole genome assembler called BOA (Berkeley Open Assembler) that will easily scale to mammalian genomes.

  9. Persistent homology and string vacua

    NASA Astrophysics Data System (ADS)

    Cirafici, Michele

    2016-03-01

    We use methods from topological data analysis to study the topological features of certain distributions of string vacua. Topological data analysis is a multi-scale approach used to analyze the topological features of a dataset by identifying which homological characteristics persist over a long range of scales. We apply these techniques in several contexts. We analyze {N}=2 vacua by focusing on certain distributions of Calabi-Yau varieties and Landau-Ginzburg models. We then turn to flux compactifications and discuss how we can use topological data analysis to extract physical information. Finally we apply these techniques to certain phenomenologically realistic heterotic models. We discuss the possibility of characterizing string vacua using the topological properties of their distributions.

  10. Filter for a drill string

    DOEpatents

    Hall, David R.; Pixton, David S.; Briscoe, Michael; McPherson, James

    2007-12-04

    A filter for a drill string comprises a perforated receptacle having an open end and a perforated end and first and second mounting surfaces are adjacent the open end. A transmission element is disposed within each of the first and second mounting surfaces. A capacitor may modify electrical characteristics of an LC circuit that comprises the transmission elements. The respective transmission elements are in communication with each other and with a transmission network integrated into the drill string. The transmission elements may be inductive couplers, direct electrical contacts, or optical couplers. In some embodiments of the present invention, the filter comprises an electronic component. The electronic component may be selected from the group consisting of a sensor, a router, a power source, a clock source, a repeater, and an amplifier.

  11. Macroscopic constraints on string unification

    SciTech Connect

    Taylor, T.R.

    1989-03-01

    The comparison of sting theory with experiment requires a huge extrapolation from the microscopic distances, of order of the Planck length, up to the macroscopic laboratory distances. The quantum effects give rise to large corrections to the macroscopic predictions of sting unification. I discus the model-independent constraints on the gravitational sector of string theory due to the inevitable existence of universal Fradkin-Tseytlin dilatons. 9 refs.

  12. Stuck fuel rod capping sleeve

    DOEpatents

    Gorscak, Donald A.; Maringo, John J.; Nilsen, Roy J.

    1988-01-01

    A stuck fuel rod capping sleeve to be used during derodding of spent fuel assemblies if a fuel rod becomes stuck in a partially withdrawn position and, thus, has to be severed. The capping sleeve has an inner sleeve made of a lower work hardening highly ductile material (e.g., Inconel 600) and an outer sleeve made of a moderately ductile material (e.g., 304 stainless steel). The inner sleeve may be made of an epoxy filler. The capping sleeve is placed on a fuel rod which is then severed by using a bolt cutter device. Upon cutting, the capping sleeve deforms in such a manner as to prevent the gross release of radioactive fuel material

  13. Advanced gray rod control assembly

    DOEpatents

    Drudy, Keith J; Carlson, William R; Conner, Michael E; Goldenfield, Mark; Hone, Michael J; Long, Jr., Carroll J; Parkinson, Jerod; Pomirleanu, Radu O

    2013-09-17

    An advanced gray rod control assembly (GRCA) for a nuclear reactor. The GRCA provides controlled insertion of gray rod assemblies into the reactor, thereby controlling the rate of power produced by the reactor and providing reactivity control at full power. Each gray rod assembly includes an elongated tubular member, a primary neutron-absorber disposed within the tubular member said neutron-absorber comprising an absorber material, preferably tungsten, having a 2200 m/s neutron absorption microscopic capture cross-section of from 10 to 30 barns. An internal support tube can be positioned between the primary absorber and the tubular member as a secondary absorber to enhance neutron absorption, absorber depletion, assembly weight, and assembly heat transfer characteristics.

  14. A different kind of string

    NASA Astrophysics Data System (ADS)

    Caselle, Michele; Panero, Marco; Pellegrini, Roberto; Vadacchino, Davide

    2015-01-01

    In U(1) lattice gauge theory in three spacetime dimensions, the problem of confinement can be studied analytically in a semi-classical approach, in terms of a gas of monopoles with Coulomb-like interactions. In addition, this theory can be mapped to a spin model via an exact duality transformation, which allows one to perform high-precision numerical studies of the confining potential. Taking advantage of these properties, we carried out an accurate investigation of the effective string describing the low-energy properties of flux tubes in this confining gauge theory. We found striking deviations from the expected Nambu-Goto-like behavior, and, for the first time, evidence for contributions that can be described by a term proportional to the extrinsic curvature of the effective string worldsheet. Such term is allowed by Lorentz invariance, and its presence in the infrared regime of the U(1) model was indeed predicted by Polyakov several years ago. Our results show that this term scales as expected according to Polyakov's solution, and becomes the dominant contribution to the effective string action in the continuum limit. We also demonstrate analytically that the corrections to the confining potential induced by the extrinsic curvature term can be related to the partition function of the massive perturbation of a c = 1 bosonic conformal field theory. The implications of our results for SU( N ) Yang-Mills theories in three and in four spacetime dimensions are discussed.

  15. Magnetic strings in dilaton gravity

    SciTech Connect

    Dehghani, M.H.

    2005-03-15

    First, I present two new classes of magnetic rotating solutions in four-dimensional Einstein-Maxwell-dilaton gravity with Liouville-type potential. The first class of solutions yields a four-dimensional spacetime with a longitudinal magnetic field generated by a static or spinning magnetic string. I find that these solutions have no curvature singularity and no horizons, but have a conic geometry. In these spacetimes, when the rotation parameter does not vanish, there exists an electric field, and therefore the spinning string has a net electric charge which is proportional to the rotation parameter. The second class of solutions yields a spacetime with an angular magnetic field. These solutions have no curvature singularity, no horizon, and no conical singularity. The net electric charge of the strings in these spacetimes is proportional to their velocities. Second, I obtain the (n+1)-dimensional rotating solutions in Einstein-dilaton gravity with Liouville-type potential. I argue that these solutions can present horizonless spacetimes with conic singularity, if one chooses the parameters of the solutions suitable. I also use the counterterm method and compute the conserved quantities of these spacetimes.

  16. Age, growth, and maturity of the longnose sucker Catostomus catostomus, of western Lake Superior

    USGS Publications Warehouse

    Bailey, Merryll M.

    1969-01-01

    Studies of age, growth, and maturity were based on 1760 fish collected in western Lake Superior in 1964-65. The body:scale relation was curvilinear and the curve had an intercept of 1.65 inches on the length axis. The weight increased as the 2.85 power of the length. Some fish formed an annulus before May 18 in 1965; all had completed annuli by late September. Longnose suckers grew 3.6 inches the 1st year, reached 12 inches in the 6th year, and 18 inches in the 11th year. Fish from Pikes Bay grew faster than those from Gull Island Shoal. Over 6 years were required for weight to reach 1 lb and nearly 10 years to reach 2 lb. Minimum length at maturity was 10.5 inches for males and 11.5 inches for females. The youngest mature male belonged to age-group IV and the youngest mature female to age-group V. All males were mature at 14.5-14.9 inches (age-group VIII) and all females at 15.0-15.4 inches (age-group IX). Finclipped longnose suckers returned to spawn in the Brule River in successive years. One fish returned to spawn in 4 successive years. Many of the fish were not recaptured until 2 or 3 years after marking. The time of the Brule River spawning migration depended more on water temperature than on length of day. The average water temperature during the peak of the spawning runs of 1958-64 was 55.4 F. Larval suckers apparently spend little time in the Brule River and adjacent streams and drift downstream to the lake soon after hatching. The number of eggs in the ovaries of eight suckers ranged from 14 to 35 thousand and averaged 24 thousand for fish 13.9-17.7 inches long.

  17. Informing New String Programmes: Lessons Learned from an Australian Experience

    ERIC Educational Resources Information Center

    Murphy, Fintan; Rickard, Nikki; Gill, Anneliese; Grimmett, Helen

    2011-01-01

    Although there are many examples of notable string programmes there has been relatively little comparative analysis of these programmes. This paper examines three benchmark string programmes (The University of Illinois String Project, The Tower Hamlets String Teaching Project and Colourstrings) alongside Music4All, an innovative string programme…

  18. Preliminary juvenile Lost River and shortnose sucker investigations in Clear Lake, California--2011 pilot study summary

    USGS Publications Warehouse

    Burdick, Summer M.; Rasmussen, Josh

    2012-01-01

    Poor recruitment appears to limit the recovery of Lost River and shortnose sucker populations in Clear Lake Reservoir, California, but the cause is unknown. Adult suckers migrate up Willow Creek and its tributaries to spawn in some years, but low flow in Willow Creek may inhibit spawning migrations in other years. It is unclear whether spawning is successful, larvae survive, or juveniles persist to adulthood. Environmental variables associated with successful spawning or young-of-year survival have not been identified and early life history for these populations is poorly understood. The U.S. Geological Survey in cooperation with the U.S. Fish and Wildlife Service and Ruby Pipeline L.L.C. Corporation (El Paso, Tex.) initiated a study in 2011 to better understand juvenile sucker life history in Clear Lake Reservoir, and to identify constraints in the early life history that may limit recruitment to the adult spawning populations. This is a report on the 2011 pilot study for this project.

  19. Correlation of gene expression and contaminant concentrations in wild largescale suckers: a field-based study.

    PubMed

    Christiansen, Helena E; Mehinto, Alvine C; Yu, Fahong; Perry, Russell W; Denslow, Nancy D; Maule, Alec G; Mesa, Matthew G

    2014-06-15

    Toxic compounds such as organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ether flame retardants (PBDEs) have been detected in fish, birds, and aquatic mammals that live in the Columbia River or use food resources from within the river. We developed a custom microarray for largescale suckers (Catostomus macrocheilus) and used it to investigate the molecular effects of contaminant exposure on wild fish in the Columbia River. Using Significance Analysis of Microarrays (SAM) we identified 72 probes representing 69 unique genes with expression patterns that correlated with hepatic tissue levels of OCs, PCBs, or PBDEs. These genes were involved in many biological processes previously shown to respond to contaminant exposure, including drug and lipid metabolism, apoptosis, cellular transport, oxidative stress, and cellular chaperone function. The relation between gene expression and contaminant concentration suggests that these genes may respond to environmental contaminant exposure and are promising candidates for further field and laboratory studies to develop biomarkers for monitoring exposure of wild fish to contaminant mixtures found in the Columbia River Basin. The array developed in this study could also be a useful tool for studies involving endangered sucker species and other sucker species used in contaminant research. PMID:24050789

  20. Correlation of gene expression and contaminant concentrations in wild largescale suckers: a field-based study.

    PubMed

    Christiansen, Helena E; Mehinto, Alvine C; Yu, Fahong; Perry, Russell W; Denslow, Nancy D; Maule, Alec G; Mesa, Matthew G

    2014-06-15

    Toxic compounds such as organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ether flame retardants (PBDEs) have been detected in fish, birds, and aquatic mammals that live in the Columbia River or use food resources from within the river. We developed a custom microarray for largescale suckers (Catostomus macrocheilus) and used it to investigate the molecular effects of contaminant exposure on wild fish in the Columbia River. Using Significance Analysis of Microarrays (SAM) we identified 72 probes representing 69 unique genes with expression patterns that correlated with hepatic tissue levels of OCs, PCBs, or PBDEs. These genes were involved in many biological processes previously shown to respond to contaminant exposure, including drug and lipid metabolism, apoptosis, cellular transport, oxidative stress, and cellular chaperone function. The relation between gene expression and contaminant concentration suggests that these genes may respond to environmental contaminant exposure and are promising candidates for further field and laboratory studies to develop biomarkers for monitoring exposure of wild fish to contaminant mixtures found in the Columbia River Basin. The array developed in this study could also be a useful tool for studies involving endangered sucker species and other sucker species used in contaminant research.

  1. Sublethal effects of aged oil sands-affected water on white sucker (Catostomus commersonii).

    PubMed

    Arens, Collin J; Hogan, Natacha S; Kavanagh, Richard J; Mercer, Angella G; Kraak, Glen J Van Der; van den Heuvel, Michael R

    2015-03-01

    To investigate impacts of proposed oil sands aquatic reclamation techniques on benthic fish, white sucker (Catostomus commersonii Lacépède, 1803) were stocked in 2 experimental ponds-Demonstration Pond, containing aged fine tailings capped with fresh water, consistent with proposed end-pit lake designs, and South Bison Pond, containing aged unextracted oil sands material-to examine the effects of unmodified hydrocarbons. White sucker were stocked from a nearby reservoir at both sites in May 2010 and sampled 4 mo later to measure indicators of energy storage and utilization. Comparisons were then made with the source population and 2 reference lakes in the region. After exposure to aged tailings, white sucker had smaller testes and ovaries and reduced growth compared with the source population. Fish introduced to aged unextracted oil sands material showed an increase in growth over the same period. Limited available energy, endocrine disruption, and chronic stress likely contributed to the effects observed, corresponding to elevated concentrations of naphthenic acids, aromatic compounds in bile, and increased CYP1A activity. Because of the chemical and biological complexity of these systems, direct cause-effect relationships could not be identified; however, effects were associated with naphthenic acids, polycyclic aromatic hydrocarbons, ammonia, and high pH. Impacts on growth have not been previously observed in pelagic fishes examined in these systems, and may be related to differences in sediment interaction. PMID:25545538

  2. Correlation of gene expression and contaminat concentrations in wild largescale suckers: a field-based study

    USGS Publications Warehouse

    Christiansen, Helena E.; Mehinto, Alvina C.; Yu, Fahong; Perry, Russell W.; Denslow, Nancy D.; Maule, Alec G.; Mesa, Matthew G.

    2014-01-01

    Toxic compounds such as organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ether flame retardants (PBDEs) have been detected in fish, birds, and aquatic mammals that live in the Columbia River or use food resources from within the river. We developed a custom microarray for largescale suckers (Catostomus macrocheilus) and used it to investigate the molecular effects of contaminant exposure on wild fish in the Columbia River. Using Significance Analysis of Microarrays (SAM) we identified 72 probes representing 69 unique genes with expression patterns that correlated with hepatic tissue levels of OCs, PCBs, or PBDEs. These genes were involved in many biological processes previously shown to respond to contaminant exposure, including drug and lipid metabolism, apoptosis, cellular transport, oxidative stress, and cellular chaperone function. The relation between gene expression and contaminant concentration suggests that these genes may respond to environmental contaminant exposure and are promising candidates for further field and laboratory studies to develop biomarkers for monitoring exposure of wild fish to contaminant mixtures found in the Columbia River Basin. The array developed in this study could also be a useful tool for studies involving endangered sucker species and other sucker species used in contaminant research.

  3. Analysis of reciprocating compressor piston rod failures

    SciTech Connect

    Tripp, H.A.; Drosjack, M.J.

    1984-02-01

    This report presents the analysis of five piston rod failures which occurred on reciprocating compressors. Calculations are shown for rod stress which includes nominal rod loading sources as well as additional loads due to unusual pressure losses in the compressor valves, flexure of the rods due to misalignment, and manufacturing errors. The additional loads were incorporated on the basis of field measurements. The stress values are used with Baquin's equation to produce fatigue life curves for the rods. Based on the calculations, recommendations for modified rods were made. The calculation procedures are described in a manner which will permit their application to other reciprocating compressors.

  4. Cosmic string evolution with a conserved charge

    NASA Astrophysics Data System (ADS)

    Oliveira, M. F.; Avgoustidis, A.; Martins, C. J. A. P.

    2012-04-01

    Cosmic strings with degrees of freedom beyond the standard Abrikosov-Nielsen-Olesen or Nambu-Goto strings are ubiquitous in field theory as well as in models with extra dimensions, such as string theoretic brane inflation scenarios. Here, we carry out an analytic study of a simplified version of one such cosmic string model. Specifically, we extend the velocity-dependent one-scale string evolution model to the case where there is a conserved microscopic charge on the string world sheet. We find that whether the standard scale-invariant evolution of the network is preserved or destroyed due to the presence of the charge will crucially depend on the amount of damping and energy losses experienced by the network. This suggests, among other things, that results derived in Minkowski space (field theory) simulations may not extend to the case of an expanding Universe.

  5. 2012 Problem 3: String of Beads

    NASA Astrophysics Data System (ADS)

    Cao, Tongyi; Zhu, Zheyuan; Gao, Wenli; Wang, Sihui

    2015-10-01

    In this paper, the motion of a string of beads is investigated. By putting forward a continuous model, we build dynamic equations to describe its motion. The numerical solutions to the equations give the dynamics of string and critical velocity of detachment. The results are consistent with the experimental data and give a good explanation for the string to fly from the edge of the beaker at certain moment.

  6. String junction as a baryonic constituent

    NASA Astrophysics Data System (ADS)

    Kalashnikova, Yu. S.; Nefediev, A. V.

    1996-02-01

    We extend the model for QCD string with quarks to consider the Mercedes Benz string configuration describing the three-quark baryon. Under the assumption of adiabatic separation of quark and string junction motion we formulate and solve the classical equation of motion for the junction. We dare to quantize the motion of the junction, and discuss the impact of these modes on the baryon spectra.

  7. Comment on 'Quantum string seal is insecure'

    SciTech Connect

    He Guangping

    2007-11-15

    An attack strategy was recently proposed by Chau [Phys. Rev. A 75, 012327 (2007)], which was claimed to be able to break all quantum string seal protocols. Here it will be shown that the attack cannot obtain nontrivial information and escape the detection simultaneously in a class of quantum string seal, including the one proposed by He [Int. J. Quantum Inf. 4, 677 (2006)]. Thus it is insufficient to conclude that all quantum string seals are insecure.

  8. Exact solutions and singularities in string theory

    SciTech Connect

    Horowitz, G.T. ); Tseytlin, A.A. )

    1994-10-15

    We construct two new classes of exact solutions to string theory which are not of the standard plane wave of gauged WZW type. Many of these solutions have curvature singularities. The first class includes the fundamental string solution, for which the string coupling vanishes near the singularity. This suggests that the singularity may not be removed by quantum corrections. The second class consists of hybrids of plane wave and gauged WZW solutions. We discuss a four-dimensional example in detail.

  9. String Fragmentation Model in Space Radiation Problems

    NASA Technical Reports Server (NTRS)

    Tang, Alfred; Johnson, Eloise (Editor); Norbury, John W.; Tripathi, R. K.

    2002-01-01

    String fragmentation models such as the Lund Model fit experimental particle production cross sections very well in the high-energy limit. This paper gives an introduction of the massless relativistic string in the Lund Model and shows how it can be modified with a simple assumption to produce formulas for meson production cross sections for space radiation research. The results of the string model are compared with inclusive pion production data from proton-proton collision experiments.

  10. Orbifold SUSY GUT from the Heterotic String

    SciTech Connect

    Kyae, Bumseok

    2008-11-23

    From the string partition function, we discuss the mass-shell and GSO projection conditions valid for Kaluza-Klein (KK) as well as massless states in the heterotic string theory compactifled on a nonprime orbifold. Using the obtained conditions we construct a 4D string standard model, which is embedded in a 6D SUSY GUT by including KK states above the compactiflcation scale. We discuss the stringy threshold corrections to gauge couplings, including the Wilson line effects.

  11. Relation between strings and ribbon knots

    NASA Astrophysics Data System (ADS)

    Ahmed, E.; El-Rifai, E. A.; Abdellatif, R. A.

    1991-02-01

    A ribbon knot can be represented as the propagation of an open string in (Euclidean) space-time. By imposing physical conditions plus an ansatz on the string scattering amplitude, we get invariant polynomials of ribbon knots which correspond to Jones and Wadati et al. polynomials for ordinary knots. Motivated by the string scattering vertices, we derive an algebra which is a generalization of Hecke and Murakami-Birman-Wenzel (BMW) algebras of knots.

  12. Quantum fluctuations of the superconducting cosmic string

    NASA Technical Reports Server (NTRS)

    Zhang, Shoucheng

    1987-01-01

    Quantum fluctuations of the proposed superconducting string with Bose charge carriers are studied in terms of the vortices on the string world sheet. In the thermodynamical limit, it is found that they appear in the form of free vortices rather than as bound pairs. This fluctuation mode violates the topological conservation law on which superconductivity is based. However, this limit may not be reached. The critical size of the superconducting string is estimated as a function of the coupling constants involved.

  13. Fermionic Subspaces of the Bosonic String

    NASA Astrophysics Data System (ADS)

    Chattaraputi, A.; Englert, F.; Houart, L.; Taormina, A.

    A universal symmetric truncation of the bosonic string Hilbert space yields all known closed fermionic string theories in ten dimensions, their D-branes and their open descendants. We highlight the crucial role played by group theory and two-dimensional conformal field theory in the construction and emphasize the predictive power of the truncation. Such circumstantial evidence points towards the existence of a mechanism which generates space-time fermions out of bosons dynamically within the framework of bosonic string theory.

  14. Fermionic subspaces of the bosonic string

    NASA Astrophysics Data System (ADS)

    Chattaraputi, Auttakit; Englert, François; Houart, Laurent; Taormina, Anne

    2003-06-01

    A universal symmetric truncation of the bosonic string Hilbert space yields all known closed fermionic string theories in ten dimensions, their D-branes and their open descendants. We highlight the crucial role played by group theory and two-dimensional conformal field theory in the construction and emphasize the predictive power of the truncation. Such circumstantial evidence points towards the existence of a mechanism which generates spacetime fermions out of bosons dynamically within the framework of bosonic string theory.

  15. Radiation from cosmic string standing waves

    PubMed

    Olum; Blanco-Pillado

    2000-05-01

    We have simulated large-amplitude standing waves on an Abelian-Higgs cosmic string in classical lattice field theory. The radiation rate falls exponentially with wavelength, as one would expect from the field profile around a gauge string. Our results agree with those of Moore and Shellard, but not with those of Vincent, Antunes, and Hindmarsh. The radiation rate falls too rapidly to sustain a scaling solution via direct radiation of particles from string length. There is thus reason to doubt claims of strong constraints on cosmic string theories from cosmic ray observations.

  16. The conformal anomaly of k-strings

    NASA Astrophysics Data System (ADS)

    Giudice, Pietro; Gliozzi, Ferdinando; Lottini, Stefano

    2007-05-01

    Simple scaling properties of correlation functions of a confining gauge theory in d-dimensions lead to the conclusion that k-string dynamics is described, in the infrared limit, by a two-dimensional conformal field theory with conformal anomaly c = (d-2)σk/σ, where σk is the k-string tension and σ that of the fundamental representation. This result applies to any gauge theory with stable k-strings. We check it in a 3D Bbb Z4 gauge model at finite temperature, where a string effect directly related to c can be clearly identified.

  17. Particles, strings and cosmology. PASCOS 98. Proceedings.

    NASA Astrophysics Data System (ADS)

    Nath, P.

    The following topics were discussed: relativistic astrophysics and cosmology; dark matter; neutrinos; neutrino oscillations; CPT violation; electroweak physics; supersymmetry phenomenology; string theory; supergravity; gauge theories; gravitation.

  18. The physics of guitar string vibrations

    NASA Astrophysics Data System (ADS)

    Perov, Polievkt; Johnson, Walter; Perova-Mello, Nataliia

    2016-01-01

    We describe laboratory experiments to study the harmonic content of standing waves in guitar strings. The experimental data were taken by using the magnetic pickup from a guitar and a digital oscilloscope with a Fast Fourier transform capability. The amplitudes of the harmonics in the measured signal depend on the location where the string is plucked, resulting in a different timbre of the sound. The relative amplitudes of transverse standing waves in a string were determined from the experimental data and also predicted from the wave equation with the boundary and initial conditions corresponding to the initial shape of the string.

  19. Spontaneous knotting of an agitated string.

    PubMed

    Raymer, Dorian M; Smith, Douglas E

    2007-10-16

    It is well known that a jostled string tends to become knotted; yet the factors governing the "spontaneous" formation of various knots are unclear. We performed experiments in which a string was tumbled inside a box and found that complex knots often form within seconds. We used mathematical knot theory to analyze the knots. Above a critical string length, the probability P of knotting at first increased sharply with length but then saturated below 100%. This behavior differs from that of mathematical self-avoiding random walks, where P has been proven to approach 100%. Finite agitation time and jamming of the string due to its stiffness result in lower probability, but P approaches 100% with long, flexible strings. We analyzed the knots by calculating their Jones polynomials via computer analysis of digital photos of the string. Remarkably, almost all were identified as prime knots: 120 different types, having minimum crossing numbers up to 11, were observed in 3,415 trials. All prime knots with up to seven crossings were observed. The relative probability of forming a knot decreased exponentially with minimum crossing number and Möbius energy, mathematical measures of knot complexity. Based on the observation that long, stiff strings tend to form a coiled structure when confined, we propose a simple model to describe the knot formation based on random "braid moves" of the string end. Our model can qualitatively account for the observed distribution of knots and dependence on agitation time and string length.

  20. Gauge invariant actions for string models

    SciTech Connect

    Banks, T.

    1986-06-01

    String models of unified interactions are elegant sets of Feynman rules for the scattering of gravitons, gauge bosons, and a host of massive excitations. The purpose of these lectures is to describe the progress towards a nonperturbative formulation of the theory. Such a formulation should make the geometrical meaning of string theory manifest and explain the many ''miracles'' exhibited by the string Feynman rules. There are some new results on gauge invariant observables, on the cosmological constant, and on the symmetries of interacting string field theory. 49 refs.

  1. Bell's Inequalities, Superquantum Correlations, and String Theory

    DOE PAGES

    Chang, Lay Nam; Lewis, Zachary; Minic, Djordje; Takeuchi, Tatsu; Tze, Chia-Hsiung

    2011-01-01

    We offermore » an interpretation of superquantum correlations in terms of a “doubly” quantum theory. We argue that string theory, viewed as a quantum theory with two deformation parameters, the string tension α ' , and the string coupling constant g s , is such a superquantum theory that transgresses the usual quantum violations of Bell's inequalities. We also discuss the ℏ → ∞ limit of quantum mechanics in this context. As a superquantum theory, string theory should display distinct experimentally observable supercorrelations of entangled stringy states.« less

  2. Open string decoupling and tachyon condensation

    NASA Astrophysics Data System (ADS)

    Chalmers, Gordon

    2001-06-01

    The amplitudes in perturbative open string theory are examined as functions of the tachyon condensate parameter. The boundary state formalism demonstrates the decoupling of the open string modes at the non-perturbative minima of the tachyon potential via a degeneration of open world-sheets and identifies an independence of the coupling constants gs and gYM at general values of the tachyon condensate. The closed string sector is generated at the quantum level; it is also generated at the classical level perturbatively through the condensation of propagating open string modes on the D-brane degrees of freedom.

  3. QCD-like behavior of high-temperature confining strings.

    PubMed

    Diamantini, M C; Trugenberger, C A

    2002-06-24

    We show that, contrary to previous string models, the high-temperature behavior of the recently proposed confining strings reproduces exactly the correct large- N QCD result, a necessary condition for any string model of confinement.

  4. Three-Rod Linear Ion Traps

    NASA Technical Reports Server (NTRS)

    Janik, Gary R.; Prestage, John D.; Maleki, Lutfollah

    1993-01-01

    Three-parallel-rod electrode structures proposed for use in linear ion traps and possibly for electrostatic levitation of macroscopic particles. Provides wider viewing angle because they confine ions in regions outside rod-electrode structures.

  5. Solid-state-laser-rod holder

    DOEpatents

    Gettemy, D.J.; Barnes, N.P.; Griggs, J.E.

    1981-08-11

    The disclosure relates to a solid state laser rod holder comprising Invar, copper tubing, and epoxy joints. Materials and coefficients of expansion of the components of the holder combine with the rod to produce a joint which will give before the rod itself will. The rod may be lased at about 70 to 80/sup 0/K and returned from such a temperature to room temperature repeatedly without its or the holder's destruction.

  6. Characterization of a novel hepadnavirus in the white sucker (Catostomus commersonii) from the Great Lakes Region of the USA

    USGS Publications Warehouse

    Hahn, Cassidy M.; Iwanowicz, Luke R.; Cornman, Robert S.; Conway, Carla M.; Winton, James R.; Blazer, Vicki S.

    2015-01-01

    The white sucker Catostomus commersonii is a freshwater teleost often utilized as a resident sentinel. Here, we sequenced the full genome of a hepatitis B-like virus that infects white suckers from the Great Lakes Region of the USA. Dideoxysequencing confirmed the white sucker hepatitis B virus (WSHBV) has a circular genome (3542 bp) with the prototypical codon organization of hepadnaviruses. Electron microscopy demonstrated that complete virions of approximately 40 nm were present in the plasma of infected fish. Compared to avi- and orthohepadnaviruses, sequence conservation of the core, polymerase and surface proteins was low and ranged from 16-27% at the amino acid level. An X protein homologue common to the orthohepadnaviruses was not present. The WSHBV genome included an atypical, presumptively non-coding region absent in previously described hepadnaviruses. Phylogenetic analyses confirmed WSHBV as distinct from previously documented hepadnaviruses. The level of divergence in protein sequences between WSHBV other hepadnaviruses, and the identification of an HBV-like sequence in an African cichlid provide evidence that a novel genus of the family Hepadnaviridae may need to be established that includes these hepatitis B-like viruses in fishes. Viral transcription was observed in 9.5% (16 of 169) of white suckers evaluated. The prevalence of hepatic tumors in these fish was 4.9%, of which only 2.4% were positive for both virus and hepatic tumors. These results are not sufficient to draw inferences regarding the association of WSHBV and carcinogenesis in white sucker.

  7. Spring and Summer Spatial Distribution of Endangered Juvenile Lost River and Shortnose Suckers in Relation to Environmental Variables in Upper Klamath Lake, Oregon: 2007 Annual Report

    USGS Publications Warehouse

    Burdick, Summer M.; VanderKooi, Scott P.; Anderson, Greer O.

    2009-01-01

    Lost River sucker Deltistes luxatus and shortnose sucker Chasmistes brevirostris were listed as endangered in 1988 for a variety of reasons including apparent recruitment failure. Upper Klamath Lake, Oregon, and its tributaries are considered the most critical remaining habitat for these two species. Age-0 suckers are often abundant in Upper Klamath Lake throughout the summer months, but catches decline dramatically between late August and early September each year, and age-1 and older subadult suckers are rare. These rapid declines in catch rates and a lack of substantial recruitment into adult sucker populations in recent years suggests sucker populations experience high mortality between their first summer and first spawn. A lack of optimal rearing habitat may exacerbate juvenile sucker mortality or restrict juvenile growth or development. In 2007, we continued research on juvenile sucker habitat use begun by the U.S. Geological Survey (USGS) in 2001. Age-0 catch rates in 2006 were more than an order of magnitude greater than in previous years, which prompted us to refocus our research from age-0 suckers to age-1 sucker distributions and habitat use. We took a two-phased approach to our research in 2007 that included preliminary spring sampling and intense summer sampling components. Spring sampling was a pilot study designed to gather baseline data on the distribution of age-1 suckers as they emerge from winter in shoreline environments throughout Upper Klamath Lake (Chapter 1). Whereas, summer sampling was designed to quantitatively estimate the influence of environmental variables on age-0 and age-1 sucker distribution throughout Upper Klamath Lake, while accounting for imperfect detection (Chapter 2). In addition to these two components, we began a project to evaluate passive integrated transponder (PIT) tag loss and the effects of PIT tags on mortality of age-1 Lost River suckers (Chapter 3). The spring pilot study built the foundation for future research

  8. Singularities and Closed String Tachyons

    SciTech Connect

    Silverstein, Eva; /SLAC /Stanford U., Phys. Dept.

    2006-03-17

    A basic problem in gravitational physics is the resolution of spacetime singularities where general relativity breaks down. The simplest such singularities are conical singularities arising from orbifold identifications of flat space, and the most challenging are spacelike singularities inside black holes (and in cosmology). Topology changing processes also require evolution through classically singular spacetimes. I briefly review how a phase of closed string tachyon condensate replaces, and helps to resolve, basic singularities of each of these types. Finally I discuss some interesting features of singularities arising in the small volume limit of compact negatively curved spaces and the emerging zoology of spacelike singularities.

  9. Extraordinary vacuum black string solutions

    SciTech Connect

    Kim, Hyeong-Chan; Lee, Jungjai

    2008-01-15

    In addition to the boosted static solution there are two other classes of stationary stringlike solutions of the vacuum Einstein equation in (4+1) dimensions. Each class is characterized by three parameters of mass, tension, and momentum flow along the fifth coordinate. We analyze the metric properties of one of the two classes, which was previously assumed to be naked singular, and show that the solution spectrum contains black string and wormhole in addition to the known naked singularity as the momentum flow to mass ratio increases. Interestingly, there does not exist new zero momentum solution in these cases.

  10. String Theory and Primordial Cosmology

    NASA Astrophysics Data System (ADS)

    Gasperini, Maurizio

    String cosmology aims at providing a reliable description of the very early Universe in the regime where standard-model physics is no longer appropriate, and where we can safely apply the basic ingredients of superstring models such as dilatonic and axionic forces, duality symmetries, winding modes, limiting sizes and curvatures, higher dimensional interactions among elementary extended object. The sought target is that of resolving (or at least alleviating) the big problems of standard and inflationary cosmology like the spacetime singularity, the physics of the trans-Planckian regime, the initial condition for inflation, and so on.

  11. String inflation after Planck 2013

    SciTech Connect

    Burgess, C.P.; Cicoli, M.; Quevedo, F. E-mail: mcicoli@ictp.it

    2013-11-01

    We briefly summarize the impact of the recent Planck measurements for string inflationary models, and outline what might be expected to be learned in the near future from the expected improvement in sensitivity to the primordial tensor-to-scalar ratio. We comment on whether these models provide sufficient added value to compensate for their complexity, and ask how they fare in the face of the new constraints on non-gaussianity and dark radiation. We argue that as a group the predictions made before Planck agree well with what has been seen, and draw conclusions from this about what is likely to mean as sensitivity to primordial gravitational waves improves.

  12. Inverted Control Rod Lock-In Device

    DOEpatents

    Brussalis, W. G.; Bost, G. E.

    1962-12-01

    A mechanism which prevents control rods from dropping out of the reactor core in the event the vessel in which the reactor is mounted should capsize is described. The mechanism includes a pivoted toothed armature which engages the threaded control rod lead screw and prevents removal of the rod whenever the armature is not attracted by the provided electromagnetic means. (AEC)

  13. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod...

  14. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod...

  15. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod...

  16. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod...

  17. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod...

  18. On the elliptic genus of three E-strings and heterotic strings

    NASA Astrophysics Data System (ADS)

    Cai, Wenhe; Huang, Min-xin; Sun, Kaiwen

    2015-01-01

    A precise formula for the elliptic genus of three E-strings is presented. The related refined free energy coincides with the result calculated from topological string on local half K3 Calabi-Yau threefold up to genus twelve. The elliptic genus of three heterotic strings computed from M9 domain walls matches with the result from orbifold formula to high orders. This confirms the n = 3 case of the recent conjecture that n pairs of E-strings can recombine into n heterotic strings.

  19. Finite volume approach for the instationary Cosserat rod model describing the spinning of viscous jets

    NASA Astrophysics Data System (ADS)

    Arne, Walter; Marheineke, Nicole; Meister, Andreas; Schiessl, Stefan; Wegener, Raimund

    2015-08-01

    The spinning of slender viscous jets can be asymptotically described by one-dimensional models that consist of systems of partial and ordinary differential equations. Whereas well-established string models only possess solutions for certain choices of parameters and configurations, the more sophisticated rod model is not limited by restrictions. It can be considered as an ɛ-regularized string model, but containing the slenderness ratio ɛ in the equations complicates its numerical treatment. We develop numerical schemes for fixed or enlarging (time-dependent) domains, using a finite volume approach in space with mixed central, up- and down-winded differences and stiffly accurate Radau methods for the time integration. For the first time, results of instationary simulations for a fixed or growing jet in a rotational spinning process are presented for arbitrary parameter ranges.

  20. Cosmic strings with twisted magnetic flux lines and wound-strings in extra dimensions

    SciTech Connect

    Lake, Matthew; Yokoyama, Jun'ichi E-mail: yokoyama@resceu.s.u-tokyo.ac.jp

    2012-09-01

    We consider a generalization of the Nielsen-Olesen ansatz, in the abelian-Higgs model, which describes strings with twisted magnetic flux lines in the vortex core. The solution does not possess cylindrical symmetry, which leads to the existence of components of conserved momentum, both around the core-axis and along the length of the string. In addition, we consider a model of F-strings with rotating, geodesic windings in the compact space of the Klebanov-Strassler geometry and determine matching conditions which ensure energy and momentum conservation when loops chop off from the long-string network. We find that the expressions for the constants of motion, which determine the macroscopic string dynamics, can be made to coincide with those for the twisted flux line string, suggesting that extra-dimensional effects for F-strings may be mimicked by field-theoretic structure in topological defects.

  1. Topological string theory revisited I: The stage

    NASA Astrophysics Data System (ADS)

    Jia, Bei

    2016-08-01

    In this paper, we reformulate topological string theory using supermanifolds and supermoduli spaces, following the approach worked out by Witten (Superstring perturbation theory revisited, arXiv:1209.5461). We intend to make the construction geometrical in nature, by using supergeometry techniques extensively. The goal is to establish the foundation of studying topological string amplitudes in terms of integration over appropriate supermoduli spaces.

  2. Generalized string models and their semiclassical approximation

    NASA Astrophysics Data System (ADS)

    Elizalde, E.

    1984-04-01

    We construct an extensive family of Bose string models, all of them classically equivalent to the Nambu and Eguchi models. The new models involve an arbitrary analytical function f(u), with f(0)=0, and are based on the Brink-Di Vecchia-Howe and Polyakov string action. The semiclassical approximation of the models is worked out in detail.

  3. Cosmic microwave anisotropies from BPS semilocal strings

    SciTech Connect

    Urrestilla, Jon; Bevis, Neil; Hindmarsh, Mark; Kunz, Martin; Liddle, Andrew R E-mail: n.bevis@imperial.ac.uk E-mail: martin.kunz@physics.unige.ch

    2008-07-15

    We present the first ever calculation of cosmic microwave background (CMB) anisotropy power spectra from semilocal cosmic strings, obtained via simulations of a classical field theory. Semilocal strings are a type of non-topological defect arising in some models of inflation motivated by fundamental physics, and are thought to relax the constraints on the symmetry breaking scale as compared to models with (topological) cosmic strings. We derive constraints on the model parameters, including the string tension parameter {mu}, from fits to cosmological data, and find that in this regard Bogomol'nyi-Prasad-Sommerfield (BPS) semilocal strings resemble global textures more than topological strings. The observed microwave anisotropy at l=10 is reproduced if G{mu} = 5.3 Multiplication-Sign 10{sup -6} (G is Newton's constant). However as with other defects the spectral shape does not match observations, and in models with inflationary perturbations plus semilocal strings the 95% confidence level upper bound is G{mu}<2.0 Multiplication-Sign 10{sup -6} when CMB, Hubble key project and big bang nucleosynthesis data are used (cf G{mu}<0.9 Multiplication-Sign 10{sup -6} for cosmic strings). We additionally carry out a Bayesian model comparison of several models with and without defects, showing that models with defects are neither conclusively favoured nor disfavoured at present.

  4. Density fluctuations from strings and galaxy formation

    NASA Technical Reports Server (NTRS)

    Vilenkin, A.; Shafi, Q.

    1983-01-01

    The spectra of density fluctuations caused by strings in a universe dominated either by baryons, neutrinos, or axions are presented. Realistic scenarios for galaxy formation seem possible in all three cases. Examples of grand unified theories which lead to strings with the desired mass scales are given.

  5. A Computer String-Grammar of English.

    ERIC Educational Resources Information Center

    Sager, Naomi

    This volume is the fourth in a series of detailed reports on a working computer program for the syntactic analysis of English sentences into their component strings. The report (1) records the considerations involved in various decisions among alternative grammatical formulations and presents the word-subclasses, the linguistic strings, etc., for…

  6. Hydromonochord: Visualizing String Vibration by Water Swirls

    ERIC Educational Resources Information Center

    Sommer, Wilfried; Meier-Boke, Ralf; Meinzer, Nicholas

    2010-01-01

    The hydromonochord is a horizontal vibrating string that just makes contact with the surface of a water bath. The motion of the string sets up a pattern of swirls on the surface of the water, thus complementing the usual pattern of nodes and antinodes. The device is based on the traditional monochord. A water basin (Fig. 1) has two slits in the…

  7. Higher dimensional cosmology with string vacuum energy

    SciTech Connect

    Nishimura, H.; Tabuse, M.

    1987-05-01

    The authors consider higher dimensional cosmology based on the closed bosonic string theory with the one-loop vacuum energy. It is concluded that the winding effect of strings around tori has a chance to prevent the extra space from expanding, even though the curvature of torus is zero.

  8. String Theory: Big Problem for Small Size

    ERIC Educational Resources Information Center

    Sahoo, S.

    2009-01-01

    String theory is the most promising candidate theory for a unified description of all the fundamental forces that exist in nature. It provides a mathematical framework that combines quantum theory with Einstein's general theory of relativity. The typical size of a string is of the order of 10[superscript -33] cm, called the Planck length. But due…

  9. From surface roughening to QCD string theory

    SciTech Connect

    Keisuke Jimmy Juge et al.

    2001-05-23

    Surface critical phenomena and the related onset of Goldstone modes represent fundamental properties of the confining flux in Quantum Chromodynamics. New ideas on surface roughening and their implications for lattice studies of quark confinement and string formation are presented. Problems with a simple string description of the large Wilson surface are discussed.

  10. Micro string resonators as temperature sensors

    NASA Astrophysics Data System (ADS)

    Larsen, T.; Schmid, S.; Boisen, A.

    2013-09-01

    The resonance frequency of strings is highly sensitive to temperature. In this work we have investigated the applicability of micro string resonators as temperature sensors. The resonance frequency of strings is a function of the tensile stress which is coupled to temperature by the thermal expansion of the string and the frame clamping it. The sensitivity improves when the length and pre-stress are reduced and the difference in thermal expansion, Young's modulus and resonant mode are increased. At low tensile stress, the sensitivity becomes highly dependent on temperature. The investigation was done with silicon rich silicon nitride (SiNx), nickel (Ni) and aluminum (Al) micro strings. Aluminum strings show a relative sensitivity of up to 15±1 %/°C, which is more than 100 times higher than values reported by other groups for similar devices. Sub-millisecond time constants can be achieved due to the low thermal mass of the strings. A temperature resolution of 2.5×10-4 °C has been achieved with silicon nitride strings. The theoretical limit for the temperature resolution of 8×10-8 °C has not been reached yet and requires further improvement of the sensor.

  11. Melt dumping in string stabilized ribbon growth

    DOEpatents

    Sachs, Emanuel M.

    1986-12-09

    A method and apparatus for stabilizing the edge positions of a ribbon drawn from a melt includes the use of wettable strings drawn in parallel up through the melt surface, the ribbon being grown between the strings. A furnace and various features of the crucible used therein permit continuous automatic growth of flat ribbons without close temperature control or the need for visual inspection.

  12. Face recognition using ensemble string matching.

    PubMed

    Chen, Weiping; Gao, Yongsheng

    2013-12-01

    In this paper, we present a syntactic string matching approach to solve the frontal face recognition problem. String matching is a powerful partial matching technique, but is not suitable for frontal face recognition due to its requirement of globally sequential representation and the complex nature of human faces, containing discontinuous and non-sequential features. Here, we build a compact syntactic Stringface representation, which is an ensemble of strings. A novel ensemble string matching approach that can perform non-sequential string matching between two Stringfaces is proposed. It is invariant to the sequential order of strings and the direction of each string. The embedded partial matching mechanism enables our method to automatically use every piece of non-occluded region, regardless of shape, in the recognition process. The encouraging results demonstrate the feasibility and effectiveness of using syntactic methods for face recognition from a single exemplar image per person, breaking the barrier that prevents string matching techniques from being used for addressing complex image recognition problems. The proposed method not only achieved significantly better performance in recognizing partially occluded faces, but also showed its ability to perform direct matching between sketch faces and photo faces.

  13. Plucked String on a Shoestring Budget

    ERIC Educational Resources Information Center

    Gluck, Paul

    2009-01-01

    The physics of the plucked string has been treated in many articles and books. For our 12th-grade high school physics laboratory, we have built a cheap, simple sonometer apparatus for each pair of students on which they may investigate some interesting phenomena that arise when a string is plucked. Among these are the generation of harmonics…

  14. Bonder for Solar-Cell Strings

    NASA Technical Reports Server (NTRS)

    Garwood, G.; Frasch, W.

    1982-01-01

    String bonder for solar-cell arrays eliminates tedious manual assembly procedure that could damage cell face. Vacuum arm picks up face-down cell from cell-inverting work station and transfers it to string conveyor without changing cell orientation. Arm is activated by signal from microprocessor.

  15. Natural quintessence in string theory

    SciTech Connect

    Cicoli, Michele; Pedro, Francisco G.; Tasinato, Gianmassimo E-mail: f.pedro1@physics.ox.ac.uk

    2012-07-01

    We introduce a natural model of quintessence in string theory where the light rolling scalar is radiatively stable and couples to Standard Model matter with weaker-than-Planckian strength. The model is embedded in an anisotropic type IIB compactification with two exponentially large extra dimensions and TeV-scale gravity. The bulk turns out to be nearly supersymmetric since the scale of the gravitino mass is of the order of the observed value of the cosmological constant. The quintessence field is a modulus parameterising the size of an internal four-cycle which naturally develops a potential of the order (gravitino mass){sup 4}, leading to a small dark energy scale without tunings. The mass of the quintessence field is also radiatively stable since it is protected by supersymmetry in the bulk. Moreover, this light scalar couples to ordinary matter via its mixing with the volume mode. Due to the fact that the quintessence field is a flat direction at leading order, this mixing is very small, resulting in a suppressed coupling to Standard Model particles which avoids stringent fifth-force constraints. On the other hand, if dark matter is realised in terms of Kaluza-Klein states, unsuppressed couplings between dark energy and dark matter can emerge, leading to a scenario of coupled quintessence within string theory. We study the dynamics of quintessence in our set-up, showing that its main features make it compatible with observations.

  16. Cosmic strings and chronology protection

    NASA Astrophysics Data System (ADS)

    Grant, James D. E.

    1993-03-01

    A space consisting of two rapidly moving cosmic strings has recently been constructed by Gott that contains closed timelike curves. The global structure of this space is analyzed and it is found that, away from the strings, the space is identical to a generalized Misner space. The vacuum expectation value of the energy-momentum tensor for a conformally coupled scalar field is calculated on this generalized Misner space. It is found to diverge very weakly on the chronology horizon, but more strongly on the polarized hypersurfaces. The divergence on the polarized hypersurfaces is strong enough that when the proper geodesic interval around any polarized hypersurface is of the order of the Planck length squared, the perturbation to the metric caused by the back reaction will be of the order one. Thus we expect the structure of the space will be radically altered by the back reaction before quantum gravitational effects become important. This suggests that Hawking's ``chronology protection conjecture'' holds for spaces with a noncompactly generated chronology horizon.

  17. Vibration monitoring system for drill string

    SciTech Connect

    Wassell, M.E.

    1993-07-13

    A vibration monitoring system is described for use in monitoring lateral and torsional vibrations in a drill string comprising: a drill string component having an outer surface; first accelerometer means A[sub 1] for measuring tangential acceleration; second accelerometer means A[sub 2] for measuring tangential acceleration; third accelerometer means A[sub 3] for measuring tangential acceleration; said first, second and third accelerometer means A[sub 1], A[sub 2] and A[sub 3] being mounted in said drill string component and being spaced from one another to measure acceleration forces on said drill string component tangentially with respect to the outer surface of said component wherein said first, second and third accelerometer means are adapted to measure and distinguish between lateral and torsional vibrations exerted on said drill string component.

  18. String theory of the Regge intercept.

    PubMed

    Hellerman, S; Swanson, I

    2015-03-20

    Using the Polchinski-Strominger effective string theory in the covariant gauge, we compute the mass of a rotating string in D dimensions with large angular momenta J, in one or two planes, in fixed ratio, up to and including first subleading order in the large J expansion. This constitutes a first-principles calculation of the value for the order-J(0) contribution to the mass squared of a meson on the leading Regge trajectory in planar QCD with bosonic quarks. For open strings with Neumann boundary conditions, and for closed strings in D≥5, the order-J(0) term in the mass squared is exactly calculated by the semiclassical approximation. This term in the expansion is universal and independent of the details of the theory, assuming only D-dimensional Poincaré invariance and the absence of other infinite-range excitations on the string world volume, beyond the Nambu-Goldstone bosons.

  19. String theory of the Regge intercept.

    PubMed

    Hellerman, S; Swanson, I

    2015-03-20

    Using the Polchinski-Strominger effective string theory in the covariant gauge, we compute the mass of a rotating string in D dimensions with large angular momenta J, in one or two planes, in fixed ratio, up to and including first subleading order in the large J expansion. This constitutes a first-principles calculation of the value for the order-J(0) contribution to the mass squared of a meson on the leading Regge trajectory in planar QCD with bosonic quarks. For open strings with Neumann boundary conditions, and for closed strings in D≥5, the order-J(0) term in the mass squared is exactly calculated by the semiclassical approximation. This term in the expansion is universal and independent of the details of the theory, assuming only D-dimensional Poincaré invariance and the absence of other infinite-range excitations on the string world volume, beyond the Nambu-Goldstone bosons. PMID:25839257

  20. Cosmic (p,q,r) strings

    SciTech Connect

    Jackson, Mark G.

    2007-04-15

    The spectrum of (p,q) bound states of F- and D-strings has a distinctive square-root tension formula that is hoped to be a hallmark of fundamental cosmic strings. We point out that the Bogomol'nyi-Prasad-Sommerfield (BPS) bound for vortices in N=2 supersymmetric Abelian-Higgs models also takes the square-root form. In contrast to string theory, the most general supersymmetric field theoretic model allows for (p,q,r) strings, with three classes of strings rather than two. Unfortunately, we find that there do not exist BPS solutions except in the trivial case. The issue of whether there exist non-BPS solutions which may closely resemble the square-root form is left as an open question.

  1. CMB temperature trispectrum of cosmic strings

    SciTech Connect

    Hindmarsh, Mark; Ringeval, Christophe; Suyama, Teruaki

    2010-03-15

    We provide an analytical expression for the trispectrum of the cosmic microwave background (CMB) temperature anisotropies induced by cosmic strings. Our result is derived for the small angular scales under the assumption that the temperature anisotropy is induced by the Gott-Kaiser-Stebbins effect. The trispectrum is predicted to decay with a noninteger power-law exponent l{sup -{rho}}with 6<{rho}<7, depending on the string microstructure, and thus on the string model. For Nambu-Goto strings, this exponent is related to the string mean square velocity and the loop distribution function. We then explore two classes of wave number configuration in Fourier space, the kite and trapezium quadrilaterals. The trispectrum can be of any sign and appears to be strongly enhanced for all squeezed quadrilaterals.

  2. CMB temperature trispectrum of cosmic strings

    NASA Astrophysics Data System (ADS)

    Hindmarsh, Mark; Ringeval, Christophe; Suyama, Teruaki

    2010-03-01

    We provide an analytical expression for the trispectrum of the cosmic microwave background (CMB) temperature anisotropies induced by cosmic strings. Our result is derived for the small angular scales under the assumption that the temperature anisotropy is induced by the Gott-Kaiser-Stebbins effect. The trispectrum is predicted to decay with a noninteger power-law exponent ℓ-ρ with 6<ρ<7, depending on the string microstructure, and thus on the string model. For Nambu-Goto strings, this exponent is related to the string mean square velocity and the loop distribution function. We then explore two classes of wave number configuration in Fourier space, the kite and trapezium quadrilaterals. The trispectrum can be of any sign and appears to be strongly enhanced for all squeezed quadrilaterals.

  3. Oil well pumping apparatus

    SciTech Connect

    Whatley, D. L.; Chaviers, W. M.

    1985-07-23

    The present system and apparatus for pumping an oil well damps out the stretch and over travel in sucker rod over travel particularly when the rod string approaches its point of reversal of direction either up or down. This is accomplished by decelerating the rate of travel of the rod string and at its end of travel pausing for a time period sufficient to allow rod string oscillations to damp out prior to reversal of rod string direction which due to the long length of the rod string, its weight and the weight of the trapped oil avoids breaking the rod string and the time loss occasioned thereby in both loss of well production and costly replacement of equipment and the time loss resulting therefrom. The present invention also achieves substantial recovery of hi-viscosity oil not recoverable at present by standard recovery procedures. This is accomplished with a sensor positioned to be actuated by the ram of the hydraulic drive. When the sensor is actuated, it energizes a time delay relay which holds the sucker rod string in the upper most raised position allowing the suction to be maintained on the bottom hole pump with the standing valve open. This allows the hi-viscus oil to enter the bottom hole pump barrel. When the time delay relay is released, the sucker rod string starts its downward movement closing the bottom hole standing valve. This traps the hi-viscus oil in the pump barrel which is then displaced by the downward-movement of the plunger in the bottom hole pump.

  4. ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

    DOEpatents

    Young, J.N.

    1958-04-22

    An electromagnetic apparatus for moving a rod-like member in small steps in either direction is described. The invention has particular application in the reactor field where the reactor control rods must be moved only a small distance and where the use of mechanical couplings is impractical due to the high- pressure seals required. A neutron-absorbing rod is mounted in a housing with gripping uaits that engage the rod, and coils for magnetizing the gripping units to make them grip, shift, and release the rod are located outside the housing.

  5. Exploiting rod technology. Final report

    SciTech Connect

    1990-06-01

    ROD development was proceeding apace until recent budgetary decisions caused funding support for ROD development to be drastically reduced. The funding which was originally provided by DARPA and the Balanced Technology Initiative (BTI) Office has been cut back to zero from $800K. To determine the aeroballistic coefficients of a candidate dart, ARDEC is currently supporting development out of its own 6.2 funds at about $100K. ARDEC has made slow progress toward achieving this end because of failures in the original dart during testing. It appears that the next dart design to be tested will diverge from the original concept visualized by DARPA and Science and Technology Associates (STA). STA, the design engineer, takes exception to these changes on the basis of inappropriate test conditions and insufficient testing. At this time, the full resolution of this issue will be difficult because of the current management structure, which separates the developer (ARDEC) from the designer (STA).

  6. The rod circuit in the rabbit retina.

    PubMed

    Vaney, D I; Young, H M; Gynther, I C

    1991-01-01

    Mammalian retinae have a well-defined neuronal pathway that serves rod vision. In rabbit retina, the different populations of interneurons in the rod pathway can be selectively labeled, either separately or in combination. The rod bipolar cells show protein kinase C immunoreactivity; the rod (AII) amacrine cells can be distinguished in nuclear-yellow labeled retina; the rod reciprocal (S1 & S2) amacrine cells accumulate serotonin; and the dopaminergic amacrine cells show tyrosine-hydroxylase immunoreactivity. Furthermore, intracellular dye injection of the microscopically identified interneurons enables whole-population and single-cell studies to be combined in the same tissue. Using this approach, we have been able to analyze systematically the neuronal architecture of the rod circuit across the rabbit retina and compare its organization with that of the rod circuit in central cat retina. In rabbit retina, the rod interneurons are not organized in a uniform neuronal module that is simply scaled up from central to peripheral retina. Moreover, peripheral fields in superior and inferior retina that have equivalent densities of each neuronal type show markedly different rod bipolar to AII amacrine convergence ratios, with the result that many more rod photoreceptors converge on an AII amacrine cell in superior retina. In rabbit retina, much of the convergence in the rod circuit occurs in the outer retina whereas, in central cat retina, it is more evenly distributed between the inner and outer retina.

  7. Fuel rod assembly to manifold attachment

    DOEpatents

    Donck, Harry A.; Veca, Anthony R.; Snyder, Jr., Harold J.

    1980-01-01

    A fuel element is formed with a plurality of fuel rod assemblies detachably connected to an overhead support with each of the fuel rod assemblies having a gas tight seal with the support to allow internal fission gaseous products to flow without leakage from the fuel rod assemblies into a vent manifold passageway system on the support. The upper ends of the fuel rod assemblies are located at vertically extending openings in the support and upper threaded members are threaded to the fuel rod assemblies to connect the latter to the support. The preferred threaded members are cap nuts having a dome wall encircling an upper threaded end on the fuel rod assembly and having an upper sealing surface for sealing contact with the support. Another and lower seal is achieved by abutting a sealing surface on each fuel rod assembly with the support. A deformable portion on the cap nut locks the latter against inadvertent turning off the fuel rod assembly. Orienting means on the fuel rod and support primarily locates the fuel rods azimuthally for reception of a deforming tool for the cap nut. A cross port in the fuel rod end plug discharges into a sealed annulus within the support, which serves as a circumferential chamber, connecting the manifold gas passageways in the support.

  8. Survival, movement, and health of hatchery-raised juvenile Lost River suckers within a mesocosm in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Hereford, Danielle M.; Burdick, Summer M.; Elliott, Diane G.; Dolan-Caret, Amari; Conway, Carla M.; Harris, Alta C.

    2016-01-01

    The recovery of endangered Lost River suckers (Deltistes luxatus) in Upper Klamath Lake is limited by poor juvenile survival and failure to recruit into the adult population. Poor water quality, degradation of rearing habitat, and toxic levels of microcystin are hypothesized to contribute to low juvenile survival. Studies of wild juvenile suckers are limited in that capture rates are low and compromised individuals are rarely captured in passive nets. The goal of this study was to assess the use of a mesocosm for learning about juvenile survival, movement, and health. Hatchery-raised juvenile Lost River suckers were PIT (passive integrated transponder) tagged and monitored by three vertically stratified antennas. Fish locations within the mesocosm were recorded at least every 30 minutes and were assessed in relation to vertically stratified water-quality conditions. Vertical movement patterns were analyzed to identify the timing of mortality for each fish. Most mortality occurred from July 28 to August 16, 2014. Juvenile suckers spent daylight hours near the benthos and moved throughout the entire water column during dark hours. Diel movements were not in response to dissolved-oxygen concentrations, temperature, or pH. Furthermore, low dissolved-oxygen concentrations, high temperatures, high pH, high un-ionized ammonia, or high microcystin levels did not directly cause mortality, although indirect effects may have occurred. However, water-quality conditions known to be lethal to juvenile Lost River suckers did not occur during the study period. Histological assessment revealed severe gill hyperplasia and Ichthyobodo sp. infestations in most moribund fish. For these fish, Ichthyobodo sp. was likely the cause of mortality, although it is unclear if this parasite originated in the rearing facility because fish were not screened for this parasite prior to introduction. This study has demonstrated that we can effectively use a mesocosm equipped with antennas to learn

  9. Survival, movement, and health of hatchery-raised juvenile Lost River suckers within a mesocosm in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Hereford, Danielle M.; Burdick, Summer M.; Elliott, Diane G.; Dolan-Caret, Amari; Conway, Carla M.; Harris, Alta C.

    2016-01-28

    The recovery of endangered Lost River suckers (Deltistes luxatus) in Upper Klamath Lake is limited by poor juvenile survival and failure to recruit into the adult population. Poor water quality, degradation of rearing habitat, and toxic levels of microcystin are hypothesized to contribute to low juvenile survival. Studies of wild juvenile suckers are limited in that capture rates are low and compromised individuals are rarely captured in passive nets. The goal of this study was to assess the use of a mesocosm for learning about juvenile survival, movement, and health. Hatchery-raised juvenile Lost River suckers were PIT (passive integrated transponder) tagged and monitored by three vertically stratified antennas. Fish locations within the mesocosm were recorded at least every 30 minutes and were assessed in relation to vertically stratified water-quality conditions. Vertical movement patterns were analyzed to identify the timing of mortality for each fish. Most mortality occurred from July 28 to August 16, 2014. Juvenile suckers spent daylight hours near the benthos and moved throughout the entire water column during dark hours. Diel movements were not in response to dissolved-oxygen concentrations, temperature, or pH. Furthermore, low dissolved-oxygen concentrations, high temperatures, high pH, high un-ionized ammonia, or high microcystin levels did not directly cause mortality, although indirect effects may have occurred. However, water-quality conditions known to be lethal to juvenile Lost River suckers did not occur during the study period. Histological assessment revealed severe gill hyperplasia and Ichthyobodo sp. infestations in most moribund fish. For these fish, Ichthyobodo sp. was likely the cause of mortality, although it is unclear if this parasite originated in the rearing facility because fish were not screened for this parasite prior to introduction. This study has demonstrated that we can effectively use a mesocosm equipped with antennas to learn

  10. Distribution and condition of larval and juvenile Lost River and shortnose suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Burdick, Summer M.; Brown, Daniel T.

    2010-01-01

    Federally endangered Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were once abundant throughout their range but populations have declined. They were extirpated from several lakes in the 1920s and may no longer reproduce in others. Poor recruitment to the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable or high quality rearing habitat. In addition, larval suckers may be swept downstream from suitable rearing areas in Upper Klamath Lake into Keno Reservoir, which is seasonally anoxic. The Nature Conservancy flooded about 3,600 acres (1,456 hectares) to the north of the Williamson River mouth (Tulana Unit) in October 2007 and about 1,400 acres (567 hectares) to the south and east of the Williamson River mouth (Goose Bay Unit) a year later to retain larval suckers in Upper Klamath Lake, create nursery habitat, and improve water quality. The U.S. Geological Survey joined a long-term research and monitoring program in collaboration with The Nature Conservancy, the Bureau of Reclamation, and Oregon State University in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. The primary objectives of the research were to describe habitat colonization and use by larval and juvenile suckers and non-sucker fishes and to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report summarizes data collected in 2009 by the U.S. Geological Survey as a part of this monitoring effort. The Williamson River Delta appeared to provide suitable rearing habitat for endangered larval Lost River and shortnose suckers in 2008 and 2009. Larval suckers captured in this delta typically were

  11. The strings connection: MSSM-like models from strings

    NASA Astrophysics Data System (ADS)

    Nilles, Hans Peter

    2014-05-01

    String theory constructions towards the MSSM allow us to identify some general properties that could be relevant for tests at the LHC. They originate from the geometric structure of compactification and the location of fields in extra-dimensional space. Within the framework of the heterotic MiniLandscape we extract some generic lessons for supersymmetric model building. Among them is a specific pattern of SUSY breakdown based on mirage mediation and remnants of extended supersymmetry. This leads to a split spectrum with heavy scalars of the first two families of quarks and leptons and suppressed masses for gauginos, top partners and Higgs bosons. The models exhibit some specific form of hidden supersymmetry consistent with the high mass of the Higgs boson and all presently available experimental constraints. The most compelling picture is based on precision gauge coupling unification that might be in the kinematic reach of the LHC.

  12. Temporal and Spatial Distribution of Endangered Juvenile Lost River and Shortnose Suckers in Relation to Environmental Variables in Upper Klamath Lake, Oregon: 2008 Annual Data Summary

    USGS Publications Warehouse

    Burdick, Summer M.; VanderKooi, Scott P.

    2010-01-01

    Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were listed as endangered in 1988 for a variety of reasons including apparent recruitment failure. Upper Klamath Lake, Oregon, and its tributaries are considered the most critical remaining habitat for these two species. Age-0 suckers are often abundant in Upper Klamath Lake throughout the summer months, but catches decline dramatically between late August and early September each year and age-1 and older sub-adult suckers are rare. These rapid declines in catch rates and a lack of substantial recruitment into adult sucker populations in recent years suggests sucker populations experience high mortality between their first summer and first spawn. A lack of access to, or abundance of, optimal rearing habitat may exacerbate juvenile sucker mortality or restrict juvenile growth or development. Summer age-0 sucker habitat use and distribution has been studied extensively, but many uncertainties remain about age-1 and older juvenile habitat use, distribution, and movement patterns within Upper Klamath Lake. We designed a study to examine seasonal changes in distribution of age-1 suckers in Upper Klamath Lake as they relate to depth and water quality. In this document, which meets our annual data summary and reporting obligations, we discuss the results of our second annual spring and summer sampling effort. Catch data collected in 2007 and 2008 indicate seasonal changes in age-1 and older juvenile sucker habitat use coincident with changes in water quality, which were previously undocumented. In both years during April and May, age-1 and older juvenile suckers were found in shallow water environments. Then, as water temperatures began to warm throughout Upper Klamath Lake in June, age-1 and older juvenile suckers primarily were captured along the western shore in some of the deepest available environments. Following a dramatic decrease in dissolved oxygen concentrations in Eagle Ridge

  13. A review of possible causes of nutrient enrichment and decline of endangered sucker populations in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Bortleson, Gilbert C.; Fretwell, Marvin O.

    1993-01-01

    Ten possible causes for this excessive enrichment in nutrients are described. Three of these hypotheses are suggested for immediate testing because of large-scale changes in nutrient loading that may have occurred as a result of man’s activities. These three hypotheses relate nutrient enrichment to (1) conversion of marshland to agricultural land, (2) agricultural drainage from the basin, and (3) reservoir regulation. Eleven possible hypothetical causes for the decline in sucker populations also are described. The decline in sucker population may be related to excessive nutrient enrichment (eutrophication) of the lake.

  14. Calcium spikes in toad rods.

    PubMed Central

    Fain, G L; Gerschenfeld, H M; Quandt, F N

    1980-01-01

    1. When the retina of the toad, Bufo marinus, was superfused with 6-12 mM-tetraethylammonium chloride (TEA), intracellular recordings from rods showed large, depolarizing regenerative potentials. For brief exposures to TEA, these potentials occurred during the recovery phase of the light responses; whereas, during longer exposures, they were spontaneous in darkness but suppressed during illumination. Similar regenerative potentials were observed during perfusion with 3-10 mM-4-aminopyridine and 1-2 mM-BaCl2. 2. The amplitude of the regenerative potentials depended upon the extracellular Ca concentration ([Ca2+]o). Lowering [Ca2+]o decreased their amplitude and in zero [Ca2+]o they were reversibly abolished. Increasing [Ca2+]o by 1.5-2 times produced a small hyperpolarization of membrane potential and a large augmentation in regenerative response amplitude. However, larger increases in [Ca2+]o produced large membrane hyperpolarizations and reversibly suppressed the regenerative responses. 3. High concentrations of Sr2+ in TEA also enhanced regenerative activity but did not affect the rod resting membrane potential. The amplitude of regenerative potentials increased continuously with increasing [Sr2+]o, and in 28 mM-Sr2+ the rods generated 60-70 mV action potentials, even in the absence of extracellular Na+. 4. The regenerative potentials were blocked by 25 microM-Cd2+, 50-100 microM-Co2+, 5mM-Mg2+, and 100 microM-D-600. They were unaffected by 2 microM-TTX or 2-5 mM-Na aspartate. 5. In Ringer containing 12 mM-TEA, large anode break responses could be recorded from rods at the termination of inward current pulses. These anode break responses were also suppressed by Co2+ and unaffected by TTX or Na aspartate. 6. We conclude that the membrane of toad rods contains a conductance normally selective for Ca2+, which is activated by depolarization. In normal Ringer, the inward current through this conductance produces little effect, since it is balanced by a large outward

  15. Self-recognition mechanism between skin and suckers prevents octopus arms from interfering with each other.

    PubMed

    Nesher, Nir; Levy, Guy; Grasso, Frank W; Hochner, Binyamin

    2014-06-01

    Controlling movements of flexible arms is a challenging task for the octopus because of the virtually infinite number of degrees of freedom (DOFs) [1, 2]. Octopuses simplify this control by using stereotypical motion patterns that reduce the DOFs, in the control space, to a workable few [2]. These movements are triggered by the brain and are generated by motor programs embedded in the peripheral neuromuscular system of the arm [3-5]. The hundreds of suckers along each arm have a tendency to stick to almost any object they contact [6-9]. The existence of this reflex could pose significant problems with unplanned interactions between the arms if not appropriately managed. This problem is likely to be accentuated because it is accepted that octopuses are "not aware of their arms" [10-14]. Here we report of a self-recognition mechanism that has a novel role in motor control, restraining the arms from interfering with each other. We show that the suckers of amputated arms never attach to octopus skin because a chemical in the skin inhibits the attachment reflex of the suckers. The peripheral mechanism appears to be overridden by central control because, in contrast to amputated arms, behaving octopuses sometime grab amputated arms. Surprisingly, octopuses seem to identify their own amputated arms, as they treat arms of other octopuses like food more often than their own. This self-recognition mechanism is a novel peripheral component in the embodied organization of the adaptive interactions between the octopus's brain, body, and environment [15, 16].

  16. Self-recognition mechanism between skin and suckers prevents octopus arms from interfering with each other.

    PubMed

    Nesher, Nir; Levy, Guy; Grasso, Frank W; Hochner, Binyamin

    2014-06-01

    Controlling movements of flexible arms is a challenging task for the octopus because of the virtually infinite number of degrees of freedom (DOFs) [1, 2]. Octopuses simplify this control by using stereotypical motion patterns that reduce the DOFs, in the control space, to a workable few [2]. These movements are triggered by the brain and are generated by motor programs embedded in the peripheral neuromuscular system of the arm [3-5]. The hundreds of suckers along each arm have a tendency to stick to almost any object they contact [6-9]. The existence of this reflex could pose significant problems with unplanned interactions between the arms if not appropriately managed. This problem is likely to be accentuated because it is accepted that octopuses are "not aware of their arms" [10-14]. Here we report of a self-recognition mechanism that has a novel role in motor control, restraining the arms from interfering with each other. We show that the suckers of amputated arms never attach to octopus skin because a chemical in the skin inhibits the attachment reflex of the suckers. The peripheral mechanism appears to be overridden by central control because, in contrast to amputated arms, behaving octopuses sometime grab amputated arms. Surprisingly, octopuses seem to identify their own amputated arms, as they treat arms of other octopuses like food more often than their own. This self-recognition mechanism is a novel peripheral component in the embodied organization of the adaptive interactions between the octopus's brain, body, and environment [15, 16]. PMID:24835454

  17. Effects of lake surface elevation on shoreline-spawning Lost River Suckers

    USGS Publications Warehouse

    Burdick, Summer M.; Hewitt, David A.; Rasmussen, J.E.; Hayes, Brian; Janney, Eric; Harris, Alta C.

    2015-01-01

    We analyzed remote detection data from PIT-tagged Lost River Suckers Deltistes luxatus at four shoreline spawning areas in Upper Klamath Lake, Oregon, to determine whether spawning of this endangered species was affected by low water levels. Our investigation was motivated by the observation that the surface elevation of the lake during the 2010 spawning season was the lowest in 38 years. Irrigation withdrawals in 2009 that were not replenished by subsequent winter-spring inflows caused a reduction in available shoreline spawning habitat in 2010. We compared metrics of skipped spawning, movement among spawning areas, and spawning duration across 8 years (2006-2013) that had contrasting spring water levels. Some aspects of sucker spawning were similar in all years, including few individuals straying from the shoreline areas to spawning locations in lake tributaries and consistent effects of increasing water temperatures on the accumulation of fish at the spawning areas. During the extreme low water year of 2010, 14% fewer female and 8% fewer male suckers joined the shoreline spawning aggregation than in the other years. Both males and females visited fewer spawning areas within Upper Klamath Lake in 2010 than in other years, and the median duration at spawning areas in 2010 was at least 36% shorter for females and 20% shorter for males relative to other years. Given the imperiled status of the species and the declining abundance of the population in Upper Klamath Lake, any reduction in spawning success and egg production could negatively impact recovery efforts. Our results indicate that lake surface elevations above 1,262.3-1,262.5 m would be unlikely to limit the number of spawning fish and overall egg production.

  18. Algal Toxins in Upper Klamath Lake, Oregon: Linking Water Quality to Juvenile Sucker Health

    USGS Publications Warehouse

    VanderKooi, S.P.; Burdick, S.M.; Echols, K.R.; Ottinger, C.A.; Rosen, B.H.; Wood, T.M.

    2010-01-01

    As the lead science agency for the Department of Interior, the U.S. Geological Survey is actively involved in resource issues in the Klamath River basin. Activities include research projects on endangered Lost River and shortnose suckers, threatened coho salmon, groundwater resources, seasonal runoff forecasting, water quality in Upper Klamath Lake and the Klamath River, nutrient cycling in wetlands, and assessment of land idling programs to reduce water consumption. Many of these studies are collaborations with various partners including Department of Interior agencies, Indian Tribes, and State agencies.

  19. Habitat Suitability Index Models and Instream Flow Suitability Curves: White sucker

    USGS Publications Warehouse

    Twomey, Kathleen A.; Williamson, Kathryn L.; Nelson, Patrick C.

    1984-01-01

    The white sucker (Catostomus commersoni) is a highly adaptable, freshwater fish species found in lacustrine and riverine environments from the Mackenzie River, Hudson Bay drainage, and the Labrador Peninsula; south along the Atlantic Coast to western Georgia; along the northern extremes of the Gulf States to northern Oklahoma; north through the eastern sections of Colorado, Wyomi ng, and Montana; and through A"I berta, north-central Bri t ish Col umbi a and southeastern Yukon territory (Carlander 1969; Scott and Crossman 1973).

  20. Distribution and condition of larval and juvenile Lost River and shortnose suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Burdick, Summer M.

    2012-01-01

    Federally endangered Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were once abundant throughout their range but populations have declined. They were extirpated from several lakes in the 1920s and may no longer reproduce in other lakes. Poor recruitment to the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable or high-quality rearing habitat. In addition, larval suckers may be swept downstream from suitable rearing areas in Upper Klamath Lake into Keno Reservoir, where they are assumed lost to Upper Klamath Lake populations. The Nature Conservancy flooded about 3,600 acres (1,456 hectares) to the north of the Williamson River mouth (Tulana) in October 2007, and about 1,400 acres (567 hectares) to the south and east of the Williamson River mouth (Goose Bay Farms) in October 2008, in order to retain larval suckers in Upper Klamath Lake, create nursery habitat, and improve water quality. The U.S. Geological Survey joined a long-term research and monitoring program in collaboration with The Nature Conservancy, the Bureau of Reclamation, and Oregon State University in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. The primary objectives of the research were to describe habitat colonization and use by larval and juvenile suckers and non-sucker fishes and to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report summarizes data collected in 2010 by the U.S. Geological Survey as a part of this monitoring effort and follows two annual reports on data collected in 2008 and 2009. Restoration modifications made to the Williamson River Delta appeared to provide