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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

    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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  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. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. 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.

  6. 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.

  7. 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.

  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. 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.

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  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. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. 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.

  6. 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.

  7. 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.

  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. 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.

  10. 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.

  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. 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.

  13. 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.

  14. 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.

  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. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  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. 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.

  3. 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.

  4. 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.

  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. 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.

  9. 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

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Predation on lake whitefish eggs by longnose suckers

    USGS Publications Warehouse

    Nester, Robert T.; Poe, Thomas P.

    1984-01-01

    In November 1981, we observed intense predation on lake whitefish (Coregonus clupeaformis) eggs by longnose suckers (Catostomus catostomus) on lake whitefish spawning grounds in northwestern Lake Huron. Since longnose suckers commonly frequent the same habitat used by spawning lake whitefish, there exists the potential for high losses of eggs due to sucker predation.

  19. Rodding Surgery

    MedlinePLUS

    ... of Rodding Not everyone with OI needs intramedullary (IM) rods. Children who do not fracture often and ... without replacement may be appropriate. Some Terms Explained IM rod Telescopic rods Non-telescopic rods Sliding rods ...

  20. 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.

  1. 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. ...

  2. 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...

  3. 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... Cardiopulmonary bypass cardiotomy return sucker. (a) Identification. A cardiopulmonary bypass cardiotomy return... from the chest or heart during cardiopulmonary bypass surgery. (b) Classification. Class...

  4. FACTORS INFLUENCING GROWTH AND SURVIVAL OF WHITE SUCKER, CATOSTOMUS COMMERSONI

    EPA Science Inventory

    Growth responses of the white sucker, Catostomus commersoni, were examined in relation to the influence of temperature, body size, season, daylength, light intensity, food ration level and food quality. Sucker growth was maximum at a temperature range of 19-26C, depending upon ex...

  5. 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.

  6. Cosmic strings

    NASA Astrophysics Data System (ADS)

    Vachaspati, Tanmay; Pogosian, Levon; Steer, Danile A.

    2015-06-01

    "Strings" are solutions of certain field theories, whose energy is concentrated along an infinite line. Strings exist in many field theories motivated by particle physics, and this suggests that they may exist in the universe -- hence the name "cosmic strings". String solutions are also present in condensed matter systems where they are called "vortices". In cosmological applications, strings are generally curved, dynamical, and may form closed loops. The energy of a string remains concentrated along a time-dependent curve for a duration that is very long compared to the dynamical time of the string.

  7. Hairy suckers: the surface microstructure and its possible functional significance in the Octopus vulgaris sucker

    PubMed Central

    Appel, Esther

    2014-01-01

    Summary Octopus suckers are able to attach to any smooth surface and many rough surfaces. Here, we have discovered that the sucker surface, which has been hypothesised to be responsible for sealing the orifice during adhesion, is not smooth as previously assumed, but is completely covered by a dense network of hair-like micro-outgrowths. This finding is particularly important because it provides another demonstration of the role of hair-structures in a sealing mechanism in water, similar to that previously described for clingfish and abalones. Moreover, the discovered hairs may provide an additional adhesive mechanism that works in concert with suction. The discovered surface structures might be potentially interesting for biomimetics of novel technical suction cups with improved adhesion capabilities on non-smooth surfaces. PMID:24991492

  8. Hairy suckers: the surface microstructure and its possible functional significance in the Octopus vulgaris sucker.

    PubMed

    Tramacere, Francesca; Appel, Esther; Mazzolai, Barbara; Gorb, Stanislav N

    2014-01-01

    Octopus suckers are able to attach to any smooth surface and many rough surfaces. Here, we have discovered that the sucker surface, which has been hypothesised to be responsible for sealing the orifice during adhesion, is not smooth as previously assumed, but is completely covered by a dense network of hair-like micro-outgrowths. This finding is particularly important because it provides another demonstration of the role of hair-structures in a sealing mechanism in water, similar to that previously described for clingfish and abalones. Moreover, the discovered hairs may provide an additional adhesive mechanism that works in concert with suction. The discovered surface structures might be potentially interesting for biomimetics of novel technical suction cups with improved adhesion capabilities on non-smooth surfaces. PMID:24991492

  9. String Theory

    NASA Astrophysics Data System (ADS)

    Susskind, Leonard

    2013-01-01

    After reviewing the original motivation for the formulation of string theory and what we learned from it, I discuss some of the implications of the holographic principle and of string dualities for the question of the building blocks of nature.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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

  16. String Theory

    NASA Astrophysics Data System (ADS)

    Polchinski, Joseph

    2005-06-01

    Foreword; Preface; Notation; 10. Type I and type II superstrings; 11. The heterotic string; 12. Superstring interactions; 13. D-branes; 14. Strings at strong coupling; 15. Advanced CFT; 16. Orbifolds; 17. Calabi-Yau compactification; 18. Physics in four dimensions; 19. Advanced topics; Appendix B. Spinors and SUSY in various dimensions; References; Glossary; Index.

  17. String Theory

    NASA Astrophysics Data System (ADS)

    Polchinski, Joseph

    1998-10-01

    Volume 2: Superstring Theory and Beyond, begins with an introduction to supersymmetric string theories and goes on to a broad presentation of the important advances of recent years. The book first introduces the type I, type II, and heterotic superstring theories and their interactions. It then goes on to present important recent discoveries about strongly coupled strings, beginning with a detailed treatment of D-branes and their dynamics, and covering string duality, M-theory, and black hole entropy, and discusses many classic results in conformal field theory. The final four chapters are concerned with four-dimensional string theories, and have two goals: to show how some of the simplest string models connect with previous ideas for unifying the Standard Model; and to collect many important and beautiful general results on world-sheet and spacetime symmetries.

  18. 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.

  19. Beachfront nourishment decisions: the "sucker-free rider" problem

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-06-01

    Coastal communities and beachfront property owners often respond to erosion by adding sand to restore local beaches. However, beach nourishment alters shoreline dynamics, not only at the replenishment site but also in adjacent coastal regions, as natural coastal processes shift sand from one location to another. The result is that "sucker" communities pay to build up their beaches, but that replenishment also helps protect the coastlines of "free rider" communities. The sucker-free rider situation is an example of a classic problem studied in economics and game theory frameworks.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Cosmic strings

    NASA Astrophysics Data System (ADS)

    Hindmarsh, M. B.; Kibble, T. W. B.

    1995-05-01

    The topic of cosmic strings provides a bridge between the physics of the very small and the very large. They are predicted by some unified theories of particle interactions. If they exist, they may help to explain some of the largest-scale structures seen in the Universe today. They are `topological defects' that may have been formed at phase transitions in the very early history of the Universe, analogous to those found in some condensed-matter systems --- vortex lines in liquid helium, flux tubes in type-II superconductors, or disclination lines in liquid crystals. In this review, we describe what they are, why they have been hypothesized and what their cosmological implications would be. The relevant background from the standard models of particle physics and cosmology is described in section 1. In section 2, we review the idea of symmetry breaking in field theories, and show how the defects formed are constrained by the topology of the manifold of degenerate vacuum states. We also discuss the different types of cosmic strings that can appear in different field theories. Section 3 is devoted to the dynamics of cosmic strings, and section 4 to their interaction with other fields. The formation and evolution of cosmic strings in the early Universe is the subject of section 5, while section 6 deals with their observational implications. Finally, the present status of the theory is reviewed in section 7.

  5. Does feeding behavior facilitate trophic niche partitioning in two sympatric sucker species from the American Southwest?

    PubMed

    O'Neill, Matthew W; Gibb, Alice C

    2014-01-01

    We examined two sympatric desert fishes, Sonora suckers (Catostomus insignis) and desert suckers (Pantosteus clarkii), and asked, does feeding behavior facilitate trophic niche partitioning? To answer this question, we conducted laboratory-based feeding trials to determine whether morphology alone facilitates the diet separation between the relatively unspecialized, omnivorous Sonora sucker and the more morphologically specialized, algivorous desert sucker or whether behavioral differences accompany morphological specialization. We predicted that (1) algivorous desert suckers would maximize contact between jaws and substrate and produce a large mouth-gape to facilitate scraping attached food-material; (2) omnivorous Sonora suckers would be more effective suction feeders when consuming unattached food items from the benthos; and (3) because they are anatomically specialized for scraping, desert suckers could not alter their feeding behavior when presented with different prey types, whereas relatively unspecialized Sonora suckers could vary behavior with prey type. We found that both species maximized jaw contact when feeding on benthic-attached food, although desert suckers produced a greater gape area. We also found that Sonora suckers were more effective suction feeders when feeding on benthic-unattached prey. Counter to our initial predictions, both species altered key aspects of feeding behavior in response to different prey types/locations. It appears that both sucker species can function as generalist feeders to exploit a variety of prey types within their natural habitat; indeed, this behavioral versatility may allow desert and Sonora suckers to respond to the cyclic environmental changes that are characteristic of the aquatic habitats of the American Southwest. PMID:24457922

  6. 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.

  7. 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 ...

  8. Quasiopen string

    SciTech Connect

    Roy, S.M.; Singh, V.

    1987-03-15

    The quasiopen string in D dimensions is defined by the Nambu-Goto action and the boundary conditions (x'+x)(sigma/sub ..cap alpha../,tau) = V/sub ..cap alpha../(x'-x)(sigma/sub ..cap alpha../,tau), where sigma = sigma/sub 1/ and sigma/sub 2/ denote the ends of the string, x'equivalentpartialx/partialsigma, and the V/sub ..cap alpha../ (..cap alpha.. = 1,2) are real symmetric orthogonal matrices. (The usual open string corresponds to V/sub 1/ = V/sub 2/ = -1.) We impose Poincare invariance in d dimensions, dstring action. A choice of theta/sub i/ giving a tachyon-free spectrum is thus possible if dless than or equal to10.

  9. 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.

  10. 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

  11. 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...

  12. 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.

  13. Monitoring of Adult Lost River and Shortnose Suckers in Clear Lake Reservoir, California, 2008–2010

    USGS Publications Warehouse

    Hewitt, David A.; Hayes, Brian S.

    2013-01-01

    In collaboration with the Bureau of Reclamation, the U.S. Geological Survey began a consistent monitoring program for endangered Lost River suckers (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) in Clear Lake Reservoir, California, in the fall of 2004. The program was intended to develop a more complete understanding of the Clear Lake Reservoir populations because they are important to the recovery efforts for these species. We report results from this ongoing program and include sampling efforts from fall 2008 to spring 2010. We summarize catches and passive integrated transponder (PIT) tagging efforts from trammel net sampling in fall 2008 and fall 2009, as well as detections of PIT-tagged suckers on remote antennas in the spawning tributary, Willow Creek, in spring 2009 and spring 2010. Trammel net sampling resulted in a relatively low catch of suckers in fall 2008 and a high catch of suckers in fall 2009. We attribute the high catch of suckers to low lake levels in 2009, which concentrated fish. As in previous years, shortnose suckers made up the vast majority of the sucker catch and recaptures of previously PIT-tagged suckers were relatively uncommon. Across the 2 years, we captured and tagged 389 new Lost River suckers and 2,874 new shortnose suckers. Since the program began, we have tagged a total of about 1,200 Lost River suckers and 5,900 shortnose suckers that can be detected on the remote antennas in Willow Creek. Detections of tagged suckers were low in both spring 2009 and spring 2010. The magnitude of the spawning migration was presumably small in both years because of low flows in Willow Creek; detections were similar to a previous low-flow year (spring 2007) and much lower than previous years with higher flows (spring 2006 and spring 2008). The size composition of fish captured in fall trammel net sampling over time suggests that the Lost River sucker population probably has decreased in abundance from what it was in the early 2000s. Shortnose suckers are smaller than Lost River suckers, and we are unable to infer any trend in abundance for shortnose suckers because it is impossible to separate recruitment of small fish from size selectivity of the trammel nets. Nonetheless, the substantial catch of small shortnose suckers in 2009, especially females, indicates that some new individuals recruited to the population. Problems with inferring status and population dynamics from size composition data can be overcome by a robust capture-recapture program that follows the histories of PIT-tagged individuals. Inferences from such a program are currently hindered by poor detection rates during spawning seasons with low flows in Willow Creek, which indicate that a key assumption of capture-recapture models is violated. We suggest that the most straightforward solution to this issue would be to collect detection data during the spawning season using remote PIT tag antennas in the strait between the west and east lobes of the lake.

  14. Inflation, string theory and cosmic strings

    NASA Astrophysics Data System (ADS)

    Chernoff, David F.; Tye, S.-H. Henry

    2015-02-01

    At its very beginning, the universe is believed to have grown exponentially in size via the mechanism of inflation. The almost scale-invariant density perturbation spectrum predicted by inflation is strongly supported by cosmological observations, in particular the cosmic microwave background (MB) radiation. However, the universe's precise inflationary scenario remains a profound problem for cosmology and for fundamental physics. String theory, the most-studied theory as the final physical theory of nature, should provide an answer to this question. Some of the proposals on how inflation is realized in string theory are reviewed. Since everything is made of strings, some string loops of cosmological sizes are likely to survive in the hot big bang that followed inflation. They appear as cosmic strings, which can have intricate properties. Because of the warped geometry in flux compactification of the extra spatial dimensions in string theory, some of the cosmic strings may have tensions substantially below the Planck or string scale. Such strings cluster in a manner similar to dark matter leading to hugely enhanced densities. As a result, numerous fossil remnants of the low tension cosmic strings may exist within the galaxy. They can be revealed through the optical lensing of background stars in the near future and studied in detail through gravitational wave emission. We anticipate that these cosmic strings will permit us to address central questions about the properties of string theory as well as the birth of our universe.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Suckers and other bursal structures of Pomphorhynchus bulbocolli and Acanthocephalus dirus (Acanthocephala).

    PubMed

    Doyle, L R; Gleason, L N

    1991-06-01

    Accessory copulatory structures in the bursa of Pomphorhynchus bulbocolli include 2 suckers on the inner surface and bursal rays. A stylet was present in the penis of this species. Two suckers were present in the bursa of Acanthocephalus dirus, but bursal rays and a stylet in the penis were not observed. This is the first report of suckers present in the bursas of acanthocephalans. Copulatory cement caps and holes surrounded by a ring approximating the inner bursal diameter and not covered by a cap were present on the sides of some P. bulbocolli, indicating the possibility of hypodermic insemination in this species. PMID:2040955

  1. 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. In particular, the highly rotating black hole in the X-ray binary LMC X-1 implies an upper limit on the decay constant of the QCD axion f{sub a} < or approx. 2x10{sup 17} GeV, much below the Planck mass. This reach can be improved down to the grand unification scale f{sub a}< or approx. 2x10{sup 16} GeV, by observing smaller stellar mass black holes.

  2. 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 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.

  3. 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.

  4. 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...

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. Drill string enclosure

    DOEpatents

    Jorgensen, Douglas K. (Idaho Falls, ID); Kuhns, Douglass J. (Idaho Falls, ID); Wiersholm, Otto (Idaho Falls, ID); Miller, Timothy A. (Idaho Falls, ID)

    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.

  10. 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.

  11. [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

  12. Monopoles on strings

    NASA Astrophysics Data System (ADS)

    Kibble, T. W. B.; Vachaspati, Tanmay

    2015-09-01

    In cosmological scenarios based on grand unification, string theory or braneworlds, many kinds of topological or non-topological defects, including monopoles and cosmic strings, are predicted to be formed in the early Universe. Here we review specifically the physics of composite objects involving monopoles tied to strings. There is a wide variety of these, including for example dumbbells and necklaces, depending on how many strings attach to each monopole and on the extent to which the various fluxes are confined to the strings. We also briefly survey the prospects for observing such structures, the existing observational limits, and potential evidence for a cosmological role.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Open Strings as Z2-ORBIFOLDS of Closed Strings

    NASA Astrophysics Data System (ADS)

    Nagao, Greg

    We present a modular invariant formulation of the open string in terms of the closed string. Chan-Paton factors are understood as multiplicities which arise from a factorization of the closed string. This interpretation of the Chan-Paton factors suggests that the SO(2D/2) open string is consistent to all orders of the loop expansion. We show that the open string may be viewed as a Z2-orbifold of the closed string. Relations are found between various string theories which seem to reinforce an earlier suggestion by Freund that all string theories are derivable from the D = 26 orientable closed bosonic string.

  19. 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 of these species. Future challenges fisheries biologists in the Klamath Basin face include developing a better understanding of sucker population dynamics and habitat requirements at different life stages. One of the largest challenges, however, will be the integration of biological information on suckers with an improved understanding of water quality and physical habitat processes.

  20. Assessment of status of white sucker (Catostomus commersoni) populations exposed to bleached kraft pulp mill effluent.

    PubMed

    Miller, David H; Tietge, Joseph E; McMaster, Mark E; Munkittrick, Kelly R; Xia, Xiangsheng; Ankley, Gerald T

    2013-07-01

    Credible ecological risk assessments often need to include analysis of population-level impacts. In the present study, a predictive model was developed to investigate population dynamics for white sucker (Catostomus commersoni) exposed to pulp mill effluent at a well-studied site in Jackfish Bay, Lake Superior, Canada. The model uniquely combines a Leslie population projection matrix and the logistic equation to translate changes in the fecundity and the age structure of a breeding population of white sucker exposed to pulp mill effluent to alterations in population growth rate. Application of this density-dependent population projection model requires construction of a life table for the organism of interest, a measure of carrying capacity, and an estimation of the effect of stressors on vital rates. A white sucker population existing at carrying capacity and subsequently exposed to pulp mill effluent equivalent to a documented exposure experienced during the period 1988 to 1994 in Jackfish Bay would be expected to exhibit a 34% to 51% annual decrease in recruitment during the first 5 yr of exposure and approach a population size of 71% of carrying capacity. The Jackfish Bay study site contains monitoring data for biochemical endpoints in white sucker, including circulating sex steroid concentrations, that could be combined with population modeling to utilize the model demonstrated at the Jackfish Bay study site for investigation of other white sucker populations at sites that are less data-rich. PMID:23504660

  1. Evolutionary Divergence of Duplicate Copies of the Growth Hormone Gene in Suckers (Actinopterygii: Catostomidae)

    PubMed Central

    Bart, Henry L.; Reneau, Paulette C.; Doosey, Michael H.; Bell, Charles D.

    2010-01-01

    Catostomid fishes (suckers) have duplicate copies of the growth hormone gene and other nuclear genes, due to a genome duplication event early in the groups history. Yet, paralogs of GH in suckers are more than 90% conserved in nucleotide (nt) and amino acid (aa) sequence. Within paralogs across species, variation in nt and aa sequence averages 3.33% and 4.46% for GHI, and 3.22% and 2.43% for GHII, respectively. Selection tests suggest that the two GH paralogs are under strong purifying selection. Consensus trees from phylogenetic analysis of GH coding region data for 23 species of suckers, other cypriniform fishes and outgroups resolved cypriniform relationships and relationships among GHI sequences of suckers more or less consistently with analyses based on other molecular data. However, the analysis failed to resolve all sucker GHI and GHII sequences as monophyletic sister groups. This unexpected topology did not differ significantly from topologies constrained to make all GH sequences monophyletic. We attribute this result either to limitations in our GHII data set or convergent adaptive changes in GHII of tribe Catostomini. PMID:20480002

  2. 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.

  3. QCD String as AN Effective String

    NASA Astrophysics Data System (ADS)

    Makeenko, Y.

    2013-11-01

    There are two cases where QCD string is described by an effective theory of long strings: the static potential and meson scattering amplitudes in the Regge regime. I show how the former can be solved in the mean-field approximation, justified by the large number of space-time dimensions, and argue that it turns out to be exact for the Nambu-Goto string. By adding extrinsic curvature I demonstrate how the tachyonic instability of the ground-state energy can be cured by operators less relevant in the infrared. Based on the talks given at the NBI Summer Institute "Strings, gauge theory and the LHC", Copenhagen August, 22 - September, 02 2011 and the Workshop "Low dimensional physics and gauge principles", Yerevan September 21 - 26, 2011.

  4. 78 FR 22556 - Endangered and Threatened Wildlife and Plants; Revised Recovery Plan for Lost River Sucker and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-16

    ...We, the Fish and Wildlife Service, announce the availability of the final revised recovery plan for Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris), two endangered fish species found in only a few lakes and reservoirs in the upper Klamath Basin and Lost River sub-basin in southern Oregon and northern California. The recovery plan includes recovery......

  5. 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.

  6. Sperm quality assessments for endangered razorback suckers Xyrauchen texanus.

    PubMed

    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; P<0.0001). Count (FCM) was negatively correlated with post-thaw viability (r=-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; P<0.0001) and pre-freeze viabilities (r=-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. PMID:20956577

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

    PubMed

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

    2015-02-01

    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

  8. 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.

  9. 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

  10. 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.

  11. Cosmic strings and superstrings

    NASA Astrophysics Data System (ADS)

    Copeland, E. J.; Kibble, T. W. B.

    2009-11-01

    Cosmic strings are predicted by many field-theory models, and may have been formed at a symmetry-breaking transition early in the history of the universe, such as that associated with grand unification. They could have important cosmological effects. Scenarios suggested by fundamental string theory or M-theory, in particular the popular idea of brane inflation, also strongly suggest the appearance of similar structures. Here we review the reasons for postulating the existence of cosmic strings or superstrings, the various possible ways in which they might be detected observationally, and the special features that might discriminate between ordinary cosmic strings and superstrings.

  12. 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.

  13. 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.

  14. 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.

  15. Control rod drive

    DOEpatents

    Hawke, Basil C. (Solana Beach, CA)

    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.

  16. Lightning discharge protection rod

    NASA Technical Reports Server (NTRS)

    Bryan, Charles F., Jr. (inventor)

    1987-01-01

    A system for protecting an in-air vehicle from damage due to a lighning strike is disclosed. It is an extremely simple device consisting of a sacrificial graphite composite rod, approximately the diameter of a pencil with a length of about five inches. The sacrificial rod is constructed with the graphite fibers running axially within the rod in a manner that best provides a path of conduction axially from the trailing edge of an aircraft to the trailing end of the rod. The sacrificial rod is inserted into an attachment hole machined into trailing edges of aircraft flight surfaces, such as a vertical fin cap and attached with adhesive in a manner not prohibiting the conduction path between the rod and the aircraft. The trailing end of the rod may be tapered for aerodynamic and esthetic requirements. This rod is sacrificial but has the capability to sustain several lightning strikes and still provide protection.

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

    PubMed

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

    2012-05-01

    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-? mRNA expression level was one of the indicators chosen to evaluate juvenile sucker health during the restoration process. TGF-? mRNA expression level has been correlated with disease status in several laboratory studies and TGF-? 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-? and a possible splice variant from shortnose sucker and from Lost River sucker. The performance of a quantitative RT-PCR assay to measure TGF-? 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-? and 18S as assessed by qRT-PCR was higher in samples with higher quality RNA. TGF-? mRNA expression was lower in kidney than in spleen in both Lost River sucker and shortnose sucker. PMID:22366312

  18. 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.

  19. 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.

  20. Sewing closed string amplitudes

    NASA Astrophysics Data System (ADS)

    Carlip, Steven

    1988-08-01

    We give a prescription for combining the Polyakov amplitudes for two string world-sheets with boundary by functionally integrating over boundary values of the embedding and ghost fields. The relationship between the moduli of the sewn surface and its components is investigated, and implications for string field theory are discussed.

  1. 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.

  2. 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.

  3. 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.

  4. PT-symmetric strings

    SciTech Connect

    Amore, Paolo; Fernndez, 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.

  5. 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

  6. 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. PMID:24920108

  7. 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...

  8. 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...

  9. 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

  10. Life history of the bridgelip sucker in the central Columbia River

    SciTech Connect

    Dauble, D.D.

    1980-01-01

    In the central Columbia River, southeastern Washington, bridgelip suckers (Catostomus columbianus) were common in deep water with strong currents during daylight and moved into slower shallow water at night. Mean calculated fork lengths (FL) in millimeters at annulus formation were age I, 63; II, 148; III, 224; IV, 291; V, 335; VI, 361; VII, 387; VIII, 401; IX, 408. Back calculated lengths approximated lengths at capture for respective ages. The length-weight (W) relationship for both sexes was log/sub e/W = -12.65 + 3.25 log/sub e/FL. Both sexes reached maturity at about 350 mm FL and age VI. Peak spawning in all years occurred during May in water temperatures of 8 to 13 C. Breeding males and females both exhibited a narrow red lateral line stripe. Estimated egg numbers per mature female ranged from 9,995 to 21,040. Bridgelip sucker diet was almost entirely periphyton, except fish smaller than 150 mm FL utilized mainly aquatic insect larvae and zooplankton. Variability of taxonomic characters caused some difficulty in distinguishing bridgelip suckers from sympatric largescale suckers (C. macrocheilus).

  11. WHITE SUCKER 'CATOSTOMUS COMMERSONI' EMBRYO DEVELOPMENT, AND EARLY GROWTH AND SURVIVAL AT DIFFERENT TEMPERATURES

    EPA Science Inventory

    White suckers (Catostomus commersoni) were exposed from fertilization through hatching to seven constant temperatures from 6.2 through 24.1C. High percentages of apparently normal larvae hatched at temperatures from 9.0 through 17.2C. Maximum percent hatch occurred at 15.2C, whil...

  12. Fusing E-strings to heterotic strings: E +E ?H

    NASA Astrophysics Data System (ADS)

    Haghighat, Babak; Lockhart, Guglielmo; Vafa, Cumrun

    2014-12-01

    E-strings arise from M2 branes suspended between an M5 brane and an M9 plane. In this paper we obtain explicit expressions for the elliptic genus of two E-strings using a series of string dualities. Moreover we show how this can be used to recover the elliptic genus of two E8E8 heterotic strings using the Ho?ava-Witten realization of heterotic strings in M-theory. This involves highly nontrivial identities among Jacobi forms and is remarkable in light of the fact that E-strings are "sticky" and form bound states whereas heterotic strings do not form bound states.

  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

    SUMMARY Hatchery-reared juvenile, 45-cm TL) flathead catfish. Predator-nai??ve juveniles (20- to 25-cm TL) exhibited no discernable preference when provided areas with and without (52 percent and 48 percent, n = 16 observations; 46 percent and 54 percent, n = 20 observations) large flathead catfish. However, once predation occurred, use of predator-free areas nearly doubled in two trials (36 percent and 64 percent, n = 50 observations; 33 percent and 67 percent, n = 12 observations). A more stringent test examining available area indicated predator-savvy razorback suckers used predator-free areas (88 percent, n = 21) illustrating predator avoidance was a learned behavior. 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 predator-nai??ve fish (p = 0.017). Similar tests exposing predator-savvy and predator-nai??ve 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. Music: Beginning Strings, Instrumental Techniques--Strings.

    ERIC Educational Resources Information Center

    Biringer, Frank A., Jr.; Ronci, Sal

    A course in introduction to music emphasizing modes and forms is presented. The approach used is a laboratory one in which pupils will develop skill in playing string instruments, sing, listen to, read and compose music with emphasis on identification of elementary concepts of mode and form. Course objectives include: (1) The pupil will select the

  15. String field theory

    SciTech Connect

    Kaku, M.

    1987-02-01

    In this article, the authors summarize the rapid progress in constructing string field theory actions, such as the development of the covariant BRST theory. They also present the newer geometric formulation of string field theory, from which the BRST theory and the older light cone theory can be derived from first principles. This geometric formulation allows us to derive the complete field theory of strings from two geometric principles, in the same way that general relativity and Yang-Mills theory can be derived from two principles based on global and local symmetry. The geometric formalism therefore reduces string field theory to a problem of finding an invariant under a new local gauge group they call the universal string group (USG). Thus, string field theory is the gauge theory of the universal string group in much the same way that Yang-Mills theory is the gauge theory of SU(N). The geometric formulation places superstring theory on the same rigorous group theoretical level as general relativity and gauge theory.

  16. 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.

  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. 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.

  19. Bows, Strings, and Bowing

    NASA Astrophysics Data System (ADS)

    Guettler, Knut

    It is to the credit of Franois Tourte (Paris, ca. 1747-1835) that modern bows give a more direct impact on the string than their predecessors. This feature is of utmost importance when applying off-string, bouncing techniques such as spiccato and ricochet, but even for a stroke such as martel, where quick reduction of bow force is required during the attack. With Tourte's concave-cambered bow, the bow force increases rapidly when the bow stick is falling or pressed against the string. With the old concave or straight bows, more movement, and thus time, was required for establishing comparable bow force.

  20. NEUTRINOS FROM STRINGS:. A Practical Introduction to String Theory, String Model-Building, and String Phenomenology -- Part I: Ten Dimensions

    NASA Astrophysics Data System (ADS)

    Dienes, Keith R.

    2000-07-01

    This is the written version of an introductory self-contained course on string model-building and string phenomenology given at the 1998 TASI summer school. No prior knowledge of string theory is assumed. The goal is to provide a practical, "how-to" manual on string theory, string model-building, and string phenomenology with a minimum of mathematics. These notes consist of Part I of these lectures, which cover the construction of bosonic strings, superstrings, and heterotic strings prior to compactification. These notes also develop the ten-dimensional free-fermionic construction. Part II (not published here) covers compactification, semi-realistic four-dimensional heterotic string models, and general features of low-energy string phenomenology. The complete set of lectures can be found on the Los Alamos hep-ph archive located at http://xxx.lanl.gov.

  1. Calibration of rod position indicators

    SciTech Connect

    Ginsberg, A.P.; Mooney, J.P.

    1991-04-30

    This patent describes a procedure for calibration of a rod position indicator in a nuclear reactor having movable control rods without total shutdown of the reactor. It comprises: noting that the indicated position of a rod differs from a demand position of the rod by an extent exceeding a predetermined error range, determining that the rod is actually within the predetermined error range; calculating an amount of power reduction at which the rod can be properly and safely fully inserted for the purpose of calibration of the rod position indicator; reducing power by the calculated amount, and; fully inserting the rod and calibrating the rod position indicator while withdrawing the rod.

  2. 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 in main lake areas and the eastern shore. Age-1 suckers were noticeably absent from the tributaries of Upper Klamath Lake during periods of chronically low dissolved-oxygen concentrations in the lake, refuting a previously untested hypothesis that tributaries were important age-1 sucker refuge habitats. In addition, declines in overall catch rates for age-1 suckers in August and September, despite intensive sampling, indicates that the apparent declines in abundance may be due to increased mortality and not due to sampling the wrong environments or poor detection probability. The remote detection of an age-1 juvenile sucker tagged in Short Creek and subsequently recaptured in the Link River array, more than 30 kilometers away, indicates the capacity of juvenile suckers to migrate relatively long distances. This knowledge, coupled with other remotely detected suckers in the Williamson River, indicates that juvenile sucker movement in Upper Klamath Lake may be common. In order to better quantify movement and potentially survival, future research should focus on tagging more juvenile suckers and taking advantage of the significant passive integrated transponder tag infrastructure throughout Upper Klamath Lake and its tributaries. In this data summary, we also describe the distribution of age-0 suckers in Upper Klamath Lake and its tributaries. These data corroborate findings from 2007 and 2008, which describe age-0 sucker habitat as shallow relative to depths available in Upper Klamath Lake. Similar to age-1 suckers, age-0 sucker abundances also appeared to decline in late summer, despite continued sampling throughout Upper Klamath Lake and its tributaries. In addition to low dissolved-oxygen concentrations, increased opercle deformity and anchor worm (Lernaea spp.) infection rates, as well as increased abundances of fathead minnows and other piscivorous non-native fish, may provide potential insight into the causes of juvenile sucker rarity. Opercle deformity r

  3. String gyratons in supergravity

    SciTech Connect

    Frolov, Valeri P.; Lin Fengli

    2006-05-15

    We study solutions of the supergravity equations with the stringlike sources moving with the speed of light. An exact solution is obtained for the gravitational field of a boosted ring string in any dimension greater than three.

  4. Cosmic string loop shapes

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    We analyze the shapes of cosmic string loops found in large-scale simulations of an expanding-universe string network. The simulation does not include gravitational backreaction, but we model that process by smoothing the loop using Lorentzian convolution. We find that loops at formation consist of generally straight segments separated by kinks. We do not see cusps or any cusplike structure at the scale of the entire loop, although we do see very small regions of string that move with large Lorentz boosts. However, smoothing of the string almost always introduces two cusps on each loop. The smoothing process does not lead to any significant fragmentation of loops that were in non-self-intersecting trajectories before smoothing.

  5. 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.

  6. Subsurface drill string

    DOEpatents

    Casper, William L. (Rigby, ID); Clark, Don T. (Idaho Falls, ID); Grover, Blair K. (Idaho Falls, ID); Mathewson, Rodney O. (Idaho Falls, ID); Seymour, Craig A. (Idaho Falls, ID)

    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.

  7. Fundamental cosmic strings

    NASA Astrophysics Data System (ADS)

    Davis, A.-C.; Kibble, Twb

    2005-09-01

    Cosmic strings are linear concentrations of energy that may be formed at phase transitions in the very early universe. At one time they were thought to provide a possible origin for the density inhomogeneities from which galaxies eventually develop, though this idea has been ruled out, primarily by observations of the cosmic microwave background (CMB). Fundamental strings are the supposed building blocks of all matter in superstring theory or its modern version, M-theory. These two concepts were originally very far apart, but recent developments have brought them closer. The brane-world scenario in particular suggests the existence of macroscopic fundamental strings that could well play a role very similar to that of cosmic strings.In this paper, we outline these new developments, and also analyse recent observational evidence, and prospects for the future.

  8. Instantons in string theory

    NASA Astrophysics Data System (ADS)

    Ahlén, Olof

    2015-12-01

    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 R4-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.

  9. Kerr black string flow

    NASA Astrophysics Data System (ADS)

    Sun, Meng; Huang, Yong-Chang

    2015-08-01

    We give a general illumination of a rotating black string falling into a rotating horizon in dimension D = 5. It is a configuration of one smooth intersection between these two objects when the spacetime is axisymmetric and in the limit that the thickness of the black hole is much larger than the thickness of the black string. Following this configuration, we further extend them to the rotating and charged flows.

  10. Screwed superconducting cosmic strings

    NASA Astrophysics Data System (ADS)

    Ferreira, C. N.

    2002-02-01

    We show that it is possible to build up a consistent model describing a superconducting cosmic string (SCS) endowed with torsion. A full string solution is obtained by matching the internal and external solutions. We derive the deficit angle, the geodesics of and the gravitational force on a test particle moving under the action of this screwed SCS. A couple of potential astrophysical phenomena are highlighted: the dynamics of compact objects orbiting torsioned SCS and the accretion of matter onto it.

  11. Hydroball string sensing system

    DOEpatents

    Hurwitz, Michael J. (Pittsburgh, PA); Ekeroth, Douglas E. (Delmont, PA); Squarer, David (Pittsburgh, PA)

    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.

  12. 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.

  13. 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.

  14. 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., Jr.

    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.

  15. 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.

  16. 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 cost of $62 per fish. The adult population was estimated at 1,196 (925-1,546) fish. Compared with trammel netting, confidence limits narrowed substantially, from +or- 500 percent to +or- 30 percent, reflecting more precise estimates. By-catch was limited to two common carp. No recreational game fish, waterfowl, or mammals were captured or handled during use of electrofishing. Aerial photography (2006 and 2007) suggested an annual average of 580 fish detected on imagery. Identification of species was not possible; carp commonly have been mistaken for razorback sucker. Field verification determined that the proportion of razorback suckers to other fish was 3:1. On that basis, we estimated 435 razorback suckers were photographed, which equals 8.4 razorback suckers per staff day at a cost of $78 per fish. The data did not lend itself to population estimates. Fish were more easily identified from boats, where their lateral rather than their dorsal aspect is visible. On average, 888 razorback suckers were positively identified each year. Observation rates averaged 29.6 razorback suckers per staff day at a cost less than $18 per fish observed. Sucker densities averaged 20.5 and 9.6 fish/hectare which equated to an average spawning population at Needles, Calif., of 2,520 in 2006 and 1152 in 2007. The lower 2007 estimate reflected a refinement in sampling approach which removed a sampling bias. Electrofishing and boat surveys were more cost effective than other methods tested, and they provided more accurate information without the by-catch associated with trammel netting. However, they provided different types of data. Handling fish may be necessary for research purposes but unnecessary for general trend analysis. Electrofishing was extremely effective but can harm fish if not used with caution. Unnecessary electrofishing increases the likelihood of spinal damage and possible damage to eggs and potential young, and it may alter spawning behavior or duration. B

  17. The Birth of String Theory

    NASA Astrophysics Data System (ADS)

    Cappelli, Andrea; Castellani, Elena; Colomo, Filippo; Di Vecchia, Paolo

    2012-04-01

    Part I. Overview: 1. Introduction and synopsis; 2. Rise and fall of the hadronic string G. Veneziano; 3. Gravity, unification, and the superstring J. H. Schwarz; 4. Early string theory as a challenging case study for philosophers E. Castellani; Part II. The Prehistory: The Analytic S-Matrix: 5. Introduction to Part II; 6. Particle theory in the sixties: from current algebra to the Veneziano amplitude M. Ademollo; 7. The path to the Veneziano model H. R. Rubinstein; 8. Two-component duality and strings P. G. O. Freund; 9. Note on the prehistory of string theory M. Gell-Mann; Part III. The Dual Resonance Model: 10. Introduction to Part III; 11. From the S-matrix to string theory P. Di Vecchia; 12. Reminiscence on the birth of string theory J. A. Shapiro; 13. Personal recollections D. Amati; 14. Early string theory at Fermilab and Rutgers L. Clavelli; 15. Dual amplitudes in higher dimensions: a personal view C. Lovelace; 16. Personal recollections on dual models R. Musto; 17. Remembering the 'supergroup' collaboration F. Nicodemi; 18. The '3-Reggeon vertex' S. Sciuto; Part IV. The String: 19. Introduction to Part IV; 20. From dual models to relativistic strings P. Goddard; 21. The first string theory: personal recollections L. Susskind; 22. The string picture of the Veneziano model H. B. Nielsen; 23. From the S-matrix to string theory Y. Nambu; 24. The analogue model for string amplitudes D. B. Fairlie; 25. Factorization in dual models and functional integration in string theory S. Mandelstam; 26. The hadronic origins of string theory R. C. Brower; Part V. Beyond the Bosonic String: 27. Introduction to Part V; 28. From dual fermion to superstring D. I. Olive; 29. Dual models with fermions: memoirs of an early string theorist P. Ramond; 30. Personal recollections A. Neveu; 31. Aspects of fermionic dual models E. Corrigan; 32. The dual quark models K. Bardakci and M. B. Halpern; 33. Remembering the dawn of relativistic strings J.-L. Gervais; 34. Early string theory in Cambridge: personal recollections C. Montonen; Part VI. The Superstring: 35. Introduction to Part VI; 36. Supersymmetry in string theory F. Gliozzi; 37. Gravity from strings: personal reminiscences of early developments T. Yoneya; 38. From the Nambu-Goto to the σ-model action L. Brink; 39. Locally supersymmetric action for superstring P. Di Vecchia; 40. Personal recollections E. Cremmer; 41. The scientific contributions of Joël Scherk J. H. Schwarz; Part VII. Preparing the String Renaissance: 42. Introduction to Part VII; 43. From strings to superstrings: a personal perspective M. B. Green; 44. Quarks, strings and beyond A. M. Polyakov; 45. The rise of the superstring theory A. Cappelli and F. Colomo; Appendices; Index.

  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. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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)

  6. 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.

  7. Who changes the string coupling?

    NASA Astrophysics Data System (ADS)

    Belopolsky, Alexander; Zwiebach, Barton

    1996-02-01

    In general bosonic closed string backgrounds the ghost-dilaton is not the only state in the semi-relative BRST cohomology that can change the dimensionless string coupling. This fact is used to establish complete dilaton theorems in closed string field theory. The ghost-dilaton, however, is the crucial state: for backgrounds where it becomes BRST trivial we prove that the string coupling becomes an unobservable parameter of the string action. For backgrounds where the matter CFT includes free uncompactified bosons we introduce a refined BRST problem by including the zero-modes " x" of the bosons as legal operators on the complex. We argue that string field theory can be defined on this enlarged complex and that the BRST cohomology captures accurately the notion of a string background. In this complex the ghost-dilaton appears to be the only BRST-physical state changing the string coupling.

  8. 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.

  9. Strings on bubbling geometries

    NASA Astrophysics Data System (ADS)

    Lin, Hai; Morisse, Alexander; Shock, Jonathan P.

    2010-06-01

    We study gauge theory operators which take the form of a product of a trace with a Schur polynomial, and their string theory duals. These states represent strings excited on bubbling AdS geometries which are dual to the Schur polynomials. These geometries generically take the form of multiple annuli in the phase space plane. We study the coherent state wavefunction of the lattice, which labels the trace part of the operator, for a general Young tableau and their dual description on the droplet plane with a general concentric ring pattern. In addition we identify a density matrix over the coherent states on all the geometries within a fixed constraint. This density matrix may be used to calculate the entropy of a given ensemble of operators. We finally recover the BMN string spectrum along the geodesic near any circle from the ansatz of the coherent state wave-function.

  10. Final Report Strings 2014

    SciTech Connect

    Witten, Edward

    2015-10-21

    DOE Final Report “Strings 2014” PI: Edward Witten, Institute for Advanced Study, Princeton, NJ 08540 CO-PI: Igor Klebanov, Princeton University, Princeton, NJ 08540 DOE Grant Number: DE-SC0011919 The Strings 2014 meeting was held at Princeton University in June 2014, co-sponsored by Princeton University and the Institute for Advanced Study. Plenary lectures at Strings 2014 were held in Richardson Auditorium of Princeton University. This comfortable and spacious facility easily accommodated the 616 participants registered participants at Strings 2014. The rental fee for the auditorium was $11,000. This grant provided $5,500 from the Department of Energy to pay for one-half of the cost of the facility rental and videotaping. Speakers were supported with funds from the National Science Foundation Clay Mathematics Institute, the Institute for Advanced Study and Princeton University. The organization of Strings 2014 consisted of an International Organizing Committee of 60 prominent scientists around the world, and a Local Advisory Committee consisting of an additional 15 distinguished scientists from neighboring institutions. Additionally, the Local Organizing Committee assisted them with about 15 members (mostly faculty at Princeton University and the Institute for Advanced Study). These groups (which are listed at the end of this narrative) offered important input concerning the selection of speakers and helped to ensure that the speakers were selected from the broadest possible pool. The conference was held on June 23-7 at Princeton University and the Institute for Advanced Study. The 616 registered participants included 272 participants from the United States and 344 from 32 institutions outside of the U.S. We believe that we were successful at providing 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. There were a total of 45 plenary speakers and 27 speakers at parallel sessions. (Parallel sessions were held at the Institute for Advanced Study.) Overall the speakers did an excellent job of presenting their topics and some presented surprising and novel results. The talks at Strings 2014 were videotaped and are available on the conference website: http://physics.princeton.edustrings2014/Talk_titles.shtml. One important facet of Strings 2014 and one of the reasons it was so well-attended was that it had a strong educational component. The week before the meeting, there was a summer school, Prospects in Theoretical Physics (PiTP), held at the Institute for Advanced Study on the subject of string theory. 260 graduate students attended both PiTP and Strings 2014. The group consisted of 25 females and 235 males; 208 graduate students and 52 postdocs. 129 participants were from the United States, and 131 participants came from institutions in 25 countries outside of the U.S. The Institute for Advanced Study substantially subsidized the summer school for students. Over two dozen students had the chance to give short (six minute) talks at the “gong shows” that were held at PiTP and Strings 2014, and nearly 60 students and postdocs made poster presentations at Strings 2014.

  11. Quantum String Theory

    NASA Astrophysics Data System (ADS)

    Kawamoto, Noboru; Kugo, Taichiro

    String theories seem to have created a breakthrough in theoretical physics. At long last a unified theory of all the fundamental interactions, including gravity, looks possible. This, according to theorist Stephen Hawking, will mark the end of theoretical physics as we have known it, since we will then have a single consistent theory within which to explain all natural phenomena from elementary particles to galactic superclusters. Strings themselves are extremely tiny entities, smaller than the Planck scale, which form loops whose vibrational harmonics can be used to model all the standard elementary particles. Of course the mathematical complexities of the theory are daunting, and physicists are still at a very early stage in understanding how strings and their theoretical cousins superstrings can be used. This proceedings volume gives an overview of the intense recent work in the field and reports latest developments.

  12. 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.}

  13. Finite-g Strings

    NASA Astrophysics Data System (ADS)

    Vicedo, Benoit

    2008-10-01

    In view of one day proving the AdS/CFT correspondence, a deeper understanding of string theory on certain curved backgrounds such as AdS_5xS^5 is required. In this dissertation we make a step in this direction by focusing on RxS^3. It was discovered in recent years that string theory on AdS_5xS^5 admits a Lax formulation. However, the complete statement of integrability requires not only the existence of a Lax formulation, but also that the resulting integrals of motion are in pairwise involution. This idea is central to the first part of this thesis. Exploiting this integrability we apply algebro-geometric methods to string theory on RxS^3 and obtain the general finite-gap solution. The construction is based on an invariant algebraic curve previously found in the AdS_5xS^5 case. However, encoding the dynamics of the solution requires specification of additional marked points. By restricting the symplectic structure of the string to this algebro-geometric data we derive the action-angle variables of the system. We then perform a first-principle semiclassical quantisation of string theory on RxS^3 as a toy model for strings on AdS_5xS^5. The result is exactly what one expects from the dual gauge theory perspective, namely the underlying algebraic curve discretises in a natural way. We also derive a general formula for the fluctuation energies around the generic finite-gap solution. The ideas used can be generalised to AdS_5xS^5.

  14. Deriving the four-string and open-closed string interactions from geometric string field theory

    SciTech Connect

    Kaku, M. )

    1990-02-20

    One of the questions concerning the covariant open string field theory is why there are two distinct BRST theories and why the four-string interaction appears in one version but not the other. The authors solve this mystery by showing that both theories are gauge-fixed versions of a higher gauge theory, called the geometric string field theory, with a new field, a string verbein e{sub {mu}{sigma}}{sup {nu}{rho}}, which allows us to gauge the string length and {sigma} parametrization. By fixing the gauge, the authors can derive the endpoint gauge (the covariantized light cone gauge), the midpoint gauge of Witten, or the interpolating gauge with arbitrary string length. The authors show explicitly that the four-string interaction is a gauge artifact of the geometric theory (the counterpart of the four-fermion instantaneous Coulomb term of QED). By choosing the interpolating gauge, they produce a new class of four-string interactions which smoothly interpolate between the endpoint gauge and the midpoint gauge (where it vanishes). Similarly, they can extract the closed string as a bound state of the open string, which appears in the endpoint gauge but vanishes in the midpoint gauge. Thus, the four-string and open-closed string interactions do not have to be added to the action as long as the string vierbein is included.

  15. 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.

  16. String Theory and Turbulence

    NASA Astrophysics Data System (ADS)

    Jejjala, Vishnu; Minic, Djordje; Ng, Y. Jack; Tze, Chia-Hsiung

    We propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. This string theory of turbulence should be understood in light of the AdS/CFT dictionary. Our argument is crucially based on the use of Migdal's loop variables and the self-consistent solutions of Migdal's loop equations for turbulence. In particular, there is an area law for turbulence in 2+1 dimensions related to the Kraichnan scaling.

  17. 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.

  18. Probing the String Landscape

    ScienceCinema

    Keith Dienes

    2010-01-08

    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.

  19. Conformal Collineations in String Cosmology

    NASA Astrophysics Data System (ADS)

    Baysal, Hsn; Camci, U.?ur; Tarhan, ?smail; Yilmaz, ?hsan; Yavuz, ?lhami; Dolgov, A.

    In this paper, we study the consequences of the existence of conformal collineations (CC) for string cloud in the context of general relativity. Especially, we interest in special conformal collineation (SCC), generated by a special affine conformal collineation (SACC) in the string cloud. Some results on the restrictions imposed by a conformal collineation symmetry in the string cloud are obtained.

  20. 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.

  1. 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.

  2. 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…

  3. 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.

  4. 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.

  5. Cosmic string loop microlensing

    NASA Astrophysics Data System (ADS)

    Bloomfield, Jolyon K.; Chernoff, David F.

    2014-06-01

    Cosmic superstring loops within the galaxy microlens background point sources lying close to the observer-string line of sight. For suitable alignments, multiple paths coexist and the (achromatic) flux enhancement is a factor of two. We explore this unique type of lensing by numerically solving for geodesics that extend from source to observer as they pass near an oscillating string. We characterize the duration of the flux doubling and the scale of the image splitting. We probe and confirm the existence of a variety of fundamental effects predicted from previous analyses of the static infinite straight string: the deficit angle, the Kaiser-Stebbins effect, and the scale of the impact parameter required to produce microlensing. Our quantitative results for dynamical loops vary by O(1) factors with respect to estimates based on infinite straight strings for a given impact parameter. A number of new features are identified in the computed microlensing solutions. Our results suggest that optical microlensing can offer a new and potentially powerful methodology for searches for superstring loop relics of the inflationary era.

  6. 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,

  7. A String Teachers Roundtable.

    ERIC Educational Resources Information Center

    Music Educators Journal, 1979

    1979-01-01

    Seven string educators respond to questions about repertoire sources for novice players, the teaching of improvisation, weaknesses in current instructional materials, ensemble size, the integration of Suzuki's methods into traditional programs, the problems of a violinist teaching other instruments, and coordination of school and other youth…

  8. 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.

  9. 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.

  10. 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. PMID:26563661

  11. 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.

  12. Current balancing for battery strings

    DOEpatents

    Galloway, James H. (New Baltimore, MI)

    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.

  13. 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.

  14. Device for balancing parallel strings

    DOEpatents

    Mashikian, Matthew S. (Storrs, CT)

    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.

  15. 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 on post-wintering juvenile sucker distribution and habitat use studies. Only 34 percent of nets set during spring sampling (April 2 to May 29) caught juvenile suckers and catch rates were low (0.038 to 0.405 suckers/hour) and widely distributed throughout shoreline areas. Of 13 suckers sacrificed for identification, only one was determined to be a Lost River sucker. All others were either shortnose suckers or Klamath largescale Catostomus snyderi suckers, but were not identified to species. Suckers caught during the spring averaged 93 +- 2 millimeter (mm) standard length (SL; mean +- SE) and were all estimated to be a year old. Spring catches did not vary in respect to nearness to tributary streams or rivers, substrate type, area of the lake, or distance from shore. On the other hand, a higher percentage of nets caught at least one sucker when they were set within 50 meters (m) of a wetland edge (60 percent) compared to nets set 200 m from a wetland (30 percent) or in other shoreline areas (29 percent). Our results also suggest that in the spring age-1 suckers use habitats less than 2 m deep at a greater frequency than deeper environments, a trend that was reversed in the summer. Temporal trends in summer catch rates of age-0 suckers generally were similar to those in previous years, with a peak during the week of August 5. In contrast, age-1 sucker catches were relatively high until the week of July 16, but rapidly declined each week for the rest of the sampling season. Age-0 suckers were caught at higher rates than age-1 suckers though the summer, but both age groups were captured at a similar percentage of sites (age-0, 26.5 percent and age-1, 27.4 percent). Age-0 catches were composed of slightly more Lost River suckers (53.2 percent) than shortnose suckers (42.1 percent). In contrast, most age-1 suckers were shortnose suckers (72.7 percent). Our summer sampling indicates age-0 suckers within Upper Klamath Lake primarily are habitat generalists, whe

  16. 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.

  17. 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

  18. Rod Contributions to Color Perception: Linear with Rod Contrast

    PubMed Central

    Cao, Dingcai; Pokorny, Joel; Smith, Vivianne C.; Zele, Andrew J.

    2008-01-01

    At mesopic light levels, an incremental change in rod activation causes changes in color appearance. In this study, we investigated how rod mediated changes in color perception varied as a function of the magnitude of the rod contrast. Rod-mediated changes in color appearance were assessed by matching them with cone-mediated color changes. A two-channel four-primary colorimeter allowed independent control of the rods and each of the L-, M- and S-cone photoreceptor types. At all light levels, rod contributions to inferred PC, KC and MC pathway mediated vision were linearly related to the rod incremental contrast. This linear relationship could be described by a model based on primate ganglion cell responses with the assumption that rod signals were conveyed via rod-cone gap junctions at mesopic light levels. PMID:18561973

  19. 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.

  20. 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 about the timing of mortality, movement, and health of PIT-tagged hatchery-raised juvenile Lost River suckers.

  1. 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.

  2. A Warped Cosmic String

    SciTech Connect

    Slagter, R. J.

    2010-06-23

    We present a cosmic string solution in Einstein-Yang-Mills Gauss-Bonnet theory on a warped 5 dimensional space-time conform the Randall-Sundrum-2 theory. In a simplipied model, we find an exact solutions with exponential decreasing or periodic warp function. In a more general setting, where the metric- and Yang-Mills components depend on both scales and one of the YM components resides in the bulk, we find a time dependent numerical solution.

  3. 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,…

  4. Anyons from strings.

    PubMed

    Mezincescu, Luca; Townsend, Paul K

    2010-11-01

    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. PMID:21231159

  5. 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.

  6. The String of Pearls

    Energy Science and Technology Software Center (ESTSC)

    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

  7. The String of Pearls

    SciTech Connect

    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.

  8. A mode method for an elastic rod in a fluid pumping system

    NASA Astrophysics Data System (ADS)

    Beale, D. G.; Lee, S. W.

    1995-01-01

    A rod pumping system, as used to lift oil to the surface in non-flowing wells, is analyzed by describing longitudinal rod stretch vibrations as a sum of fixed-free modes. The rod oscillates vertically, driven at the fixed end by a constant speed motor through a four-bar mechanism. Equilibrium is used to derive the partial differential equation of rod upstroke and downstroke motion. The partial differential equation is reduced by modal analysis (and aided by a convenient transformation to simplify an inhomogeneous boundary condition at the plunger on the upstroke) to a set of piecewise linear (and hence non-linear) and uncoupled ordinary differential equations. Based on response studies, a one-mode representation is found to capture most of the rod string stretch at practical operating speeds, and was used to investigate the response with dimensional and non-dimensionalized equations at various crank speeds, crank lengths and damping rates.

  9. A supermembrane description of string-string duality

    NASA Astrophysics Data System (ADS)

    Aldabe, Fermin

    1997-02-01

    In the absence of macroscopic and solitonic strings, we show that the open membrane action on T3 S1/ Z2 can be mapped to the closed membrane action on K3. The main difference between the two actions is that one generates the gauge modes in the worldvolume action which is the strong coupling limit of type IIA superstring while the other action generates the gauge modes in a worldsheet action. Thus explaining membrane-string duality in D = 7, which naturally leads to string-string duality in D = 6.

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

    SciTech Connect

    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.

  11. Intramedullary rodding in osteogenesis imperfecta.

    PubMed

    Mulpuri, K; Joseph, B

    2000-01-01

    The results of intramedullary rodding of long bones of 16 children with osteogenesis imperfecta, over a 10-year period, were analyzed. Sheffield elongating rods or non-elongating rods were used. The frequency of fractures was dramatically reduced after implantation of either type of rod, and the ambulatory status improved in all instances. The results were significantly better after Sheffield rodding with regard to the frequency of complications requiring reoperations and the longevity of the rods. Migration of the rods, encountered frequently, appears to be related to improper placement of the rods in the bone. It seems likely that if care is taken to ensure precise placement of a rod of appropriate size, several of these complications may be avoided. PMID:10739296

  12. 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.

  13. 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 larger than those captured in the adjacent lake habitat in 2008, but the opposite was true for larval shortnose suckers in 2009. Mean sample density was greater for both species in the Williamson River Delta than adjacent lake habitats in both years. Larval suckers captured in the restoration area, however, had less food in their guts compared to those captured in Upper Klamath or Agency Lakes. Differential distribution among sucker species within the Williamson River Delta and between the delta and adjacent lakes indicated that shortnose suckers likely benefited more from the restored Williamson River Delta than Lost River or Klamath largescale suckers (Catostomus snyderi). Catch rates in shallow-water habitats with vegetation within the delta were higher for shortnose and Klamath largescale suckers than for larval Lost River suckers in 2008 and 2009.However, catch rates at the mouth of the Williamson River in 2008 and in Upper Klamath Lake in 2009 were higher for larval Lost River suckers than for larvae identified as either shortnose or Klamath largescale suckers. Shortnose suckers also comprised the greatest portion of age-0 suckers captured in the Williamson River Delta in 2008 and 2009. The relative abundance of age-1 shortnose suckers was high in our catches compared to age-1 Lost River suckers in 2009 in the delta and adjacent lakes, which may or may not indicate shortnose suckers experienced better survival than Lost River suckers in 2008. Age-0 and age-1 suckers were similarly distributed throughout the Williamson River Delta in 2008 and 2009. Age-0 suckers used shallow vegetated and unvegetated habitats primarily in mid- to late July in both years. A comparison of catch rates between our study and a concurrent study in Upper Klamath Lake indicated that Goose Bay was the most used habitat in 2009 and the Tulana Unit was the one of the least used habitats in 2008 and 2009 by age-0 suckers. Catch rates for age-1 suckers, however, indicated that bo

  14. 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 Trench, juvenile suckers were no longer found along the western shore but were captured throughout the rest of Upper Klamath Lake. When dissolved oxygen concentrations were 4 milligrams per liter or greater along the western shore, juvenile sucker captures were again concentrated in that area. Although this pattern indicates that low dissolved oxygen concentration or another related water-quality limitation may force juvenile suckers to leave the western shore, it is unclear as to why age-1 and older juveniles might be attracted to the area in the first place. Understanding this apparent behavior could be important to managing habitat for these species. In this data summary, we also describe the distribution of catches of age-0 suckers and other fishes in Upper Klamath Lake. These data corroborate previous studies that describe age-0 sucker habitat as shallow relative to depths available in Upper Klamath Lake. In this study, we did not seek, nor find additional clarification on age-0 sucker habitat use and distribution in Upper Klamath Lake. Our brief description of the distribution and abundance of all other fish species caught provides a context in which to assess the rarity of juvenile suckers within the fish community of Upper Klamath Lake.

  15. Near-Shore and Off-Shore Habitat Use by Endangered Juvenile Lost River and Shortnose Suckers in Upper Klamath Lake, Oregon: 2006 Data Summary

    USGS Publications Warehouse

    Burdick, Summer M.; Wilkens, Alexander X.; VanderKooi, Scott P.

    2008-01-01

    INTRODUCTION Lost River suckers Deltistes luxatus and shortnose suckers Chasmistes brevirostris, listed as endangered in 1988 under the Endangered Species Act, have shown infrequent recruitment into adult populations in Upper Klamath Lake (NRC 2004). In an effort to understand the causes behind and provide management solutions to apparent recruitment failure, a number of studies have been conducted including several on larval and juvenile sucker habitat use. Near-shore areas in Upper Klamath Lake with emergent vegetation, especially those near the mouth of the Williamson River, were identified as important habitat for larval suckers (Cooperman and Markle 2000; Reiser et al. 2001). Terwilliger et al. (2004) characterized primary age-0 sucker habitat as near-shore areas in the southern portion of Upper Klamath Lake with gravel and cobble substrates. Reiser et al. (2001) provided some evidence that juvenile suckers use habitats with emergent vegetation, but nothing concerning the extent or timing of use. The U.S. Geological Survey (USGS) began investigating the importance of near-shore and off-shore habitats with and without emergent vegetation for juvenile suckers in 2000. We found substantial numbers of juvenile suckers using these habitats near the mouth of the Williamson River into late August (VanderKooi and Buelow 2003). The distribution and relative abundance of juvenile suckers showed high spatial variability throughout the summer for all species combined, Lost River suckers, and shortnose suckers (VanderKooi et al. 2006; Hendrixson et al. 2007a). Results from sampling near-shore areas in 2002 suggested juvenile sucker proximity to shoreline changes depending on the presence or absence of shoreline vegetation (VanderKooi et al. 2006), whereas in 2004 and 2005 results were equivocal (Hendrixson et al. 2007a, 2007b). Research by USGS of juvenile suckers in Upper Klamath Lake conducted since 2000 provides a valuable long-term data set which can be used to evaluate multi-year trends in juvenile sucker relative abundance and habitat use. Data on the relative abundance of juvenile suckers and their habitat use patterns will provide valuable information to guide restoration and management decisions in the Upper Klamath Basin. Information on juvenile sucker catch rates may also be valuable for evaluating year class success, estimating early life stage survival rates, and predicting upper bounds of future recruitment to adult spawning populations. We continued sampling juvenile suckers in 2006 as part of an effort to develop bioenergetics models for juvenile Lost River and shortnose suckers. This study required us to collect fish to determine growth rates and energy content of juvenile suckers. We followed the sampling protocols and methods described by Hendrixson et al. (2007b) to maintain continuity and facilitate comparisons with data collected in recent years, but sampled at a reduced level of effort compared to previous years (approximately one-third) due to limited funding. Here we present a summary of catch data collected in 2006. Bioenergetics models will be reported separately.

  16. 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.

  17. 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.

  18. Non-Abelian string conductivity

    NASA Astrophysics Data System (ADS)

    Kibble, T. W. B.; Lozano, G.; Yates, A. J.

    1997-07-01

    We examine current-carrying configurations of cosmic strings in non-Abelian gauge theories. We study the solutions numerically and point out that the currents will be at best dynamically stable and not subject to any topological quantization or conservation, as in conventional models of string superconduction. We suggest that non-Abelian string loops may be unable to support persistent currents in the absence of external fields. This will have relevance to vorton stability.

  19. Cosmic rays from cosmic strings

    NASA Astrophysics Data System (ADS)

    Gill, A. J.; Kibble, T. W. B.

    1994-09-01

    It has been speculated that cosmic string networks could produce ultrahigh-energy cosmic rays as a by-product of their evolution. By making use of recent work on the evolution of such networks, it will be shown that the flux of cosmic rays from cosmologically useful, that is, GUT scale, strings, is too small to be used as a test for strings with any foreseeable technology.

  20. 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.

  1. Ecological risk assessment of irrigation drainage selenium to the endangered razorback sucker

    SciTech Connect

    Miller, J.B.

    1995-12-31

    The razorback sucker is an endangered species in the Colorado River Basin that is nearing extinction. A remnant population is threatened by contamination from irrigation drainage and other sources. Biomarkers and toxicity tests indicate reproductive impairment to adults and acute and chronic toxicity to larval fish. Adult fish are generally more than 20 years old, and no recruitment is occurring. The assessment evaluates all selenium sources, natural and man induced, to the Green River. Selenium discharged directly to the river as inorganic selenate represents a decrease in exposure compared to organic dietary sources introduced to a critical habitat. Fate and transport modeling, biotransformation, and profiling exposure at critical life history ecological boundaries are all important considerations in the risk analysis. Determining realistic safety factors for naturally occurring and essential but potentially toxic trace elements is also essential to formulate alternatives that make common sense. Establishing an obtainable cleanup criteria must consider natural background concentrations, cost effectiveness, and public acceptability. In this case it is more cost effective and provides a greater overall benefit to the river basin to remediate a non-irrigation selenium source. A multi-agency task force has been formed to select and implement remediation that is economically feasible, scientifically sound, politically acceptable, makes common sense, and that protects the razorback sucker.

  2. Dispersal of larval suckers at the Williamson River Delta, Upper Klamath Lake, Oregon, 2006-09

    USGS Publications Warehouse

    Wood, Tamara M.; Hendrixson, Heather A.; Markle, Douglas F.; Erdman, Charles S.; Burdick, Summer M.; Ellsworth, Craig M.; Buccola, Norman L.

    2012-01-01

    An advection/diffusion modeling approach was used to simulate the transport of larval suckers from spawning areas in the Williamson River, through the newly restored Williamson River Delta, to Upper Klamath Lake. The density simulations spanned the years of phased restoration, from 2006/2007 prior to any levee breaching, to 2008 when the northern part of the delta was reconnected to the lake, and 2009 when levees on both sides of the delta had been breached. Model simulation results from all four years were compared to field data using rank correlation. Spearman ρ correlation coefficients were usually significant and in the range 0.30 to 0.60, providing moderately strong validation of the model. The correlation coefficients varied with fish size class in a way that suggested that the model best described the distribution of smaller fish near the Williamson River channel, and larger fish away from the channel. When Lost River and shortnose/Klamath largescale suckers were simulated independently, the correlation results suggested that the model better described the transport and dispersal of the latter species. The incorporation of night-time-only drift behavior in the Williamson River channel neither improved nor degraded correlations with field data. The model showed that advection by currents is an important factor in larval dispersal.

  3. 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.

  4. 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.

  5. 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 additional suitable rearing habitat for endangered Lost River and shortnose suckers from 2008 to 2010 based on sucker catches. Mean larval sample density was greater for both species in the Williamson River Delta than adjacent lake habitats in all 3 years. In addition to larval suckers, at least three age classes of juvenile suckers were captured in the delta. The shallow Goose Bay Farms and Tulana Emergent were among the most used habitats by age-0 suckers in 2009. Both of these environments became inaccessible due to low water in 2010, however, and were not sampled after July 19, 2010. In contrast, age-1 sucker catches shifted from the shallow water (about 0.5-1.5 m deep) on the eastern side of the Williamson River Delta in May, to deeper water environments (greater than 2 m) by the end of June or early July in all 3 years. Differential distribution among sucker species within the Williamson River Delta and between the delta and adjacent lakes indicated that shortnose suckers likely benefited more from the restored Williamson River Delta than Lost River or Klamath largescale suckers (Catostomus snyderi). Catch rates in shallow-water habitats within the delta were higher for shortnose and Klamath largescale sucker larvae than for larval Lost River suckers in 2008, 2009, and 2010. Shortnose suckers also comprised the greatest portion of age-0 suckers captured in the Williamson River Delta in all 3 years of the study. The relative abundance of age-1 shortnose suckers was high in our catches compared to age-1 Lost River suckers in 2009 and 2010. The restored delta also created habitat for several piscivorous fishes, but only two appeared to pose a meaningful threat of predation to suckers - fathead minnows (Pimephales promelas) and yellow perch (Perca flavescens). Fathead minnows that prey on larval but not juvenile suckers dominated catches in all sampling areas. Yellow perch also were abundant throughout the study area, but based on their gape size and co-occurrence with suckers, most were only capable of preying on larvae. Low May lake-surface elevation, below average snow pack, and anticipated irrigation demands indicated late summer water levels in Upper Klamath Lake would be unusually low in 2010. In response to concerns by the Fish and Wildlife Service and The Nature Conservancy that low-water conditions might strand fish on the delta, low water seine surveys were implemented. Eleven fishes, including both endangered suckers, were captured in seine surveys, including both species of suckers, which continued to use shallow water less than 0.4 m deep through September 21. Lake elevation declined to 1,261.54 m (4,138.9 feet) in mid-September 2010, but did not appear to strand fish or cause large-scale fish mortality.

  6. 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.

  7. From strings in 6d to strings in 5d

    NASA Astrophysics Data System (ADS)

    Haghighat, Babak

    2016-01-01

    We show how recent progress in computing elliptic genera of strings in six dimensions can be used to obtain expressions for elliptic genera of strings in five-dimensional field theories which have a six-dimensional parent. We further connect our results to recent mathematical results about sheaf counting on ruled surfaces.

  8. Seasonal Distribution and Abundance of Larval and Juvenile Lost River and Shortnose Suckers in Hanks Marsh, Upper Klamath National Wildlife Refuge, Upper Klamath Lake, Oregon: 2007 Annual Report

    USGS Publications Warehouse

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

    2009-01-01

    In the summer of 2007, we undertook an assessment of larval and juvenile sucker use of Hanks Marsh in Upper Klamath Lake, Oregon. This 1,200-acre marsh on the southeastern shoreline of the lake represents part of the last remaining natural emergent wetland habitat in the lake. Because of the suspected importance of this type of habitat to larval and juvenile endangered Lost River and shortnose suckers, it was thought that sucker abundance in the marsh might be comparatively greater than in other non-vegetated areas of the lake. It also was hoped that Hanks Marsh would serve as a reference site for wetland restoration projects occurring in other areas of the lake. Our study had four objectives: to (1) examine seasonal distribution and relative abundance of larval suckers in and adjacent to Hanks Marsh in relation to habitat features such as depth, vegetation, water quality, and relative abundance of non-sucker species; (2) determine the presence or absence and describe the distribution of juvenile suckers [35 to 80 mm standard length (SL)] along the periphery of Hanks Marsh; (3) assess spatial and temporal overlap between larval suckers and their potential predators; and (4) assess suitability of water quality throughout the summer for young-of-the-year suckers. Due to the low number of suckers found in the marsh and our inability to thoroughly sample all marsh habitats due to declining lake levels during the summer, we were unable to completely address these objectives in this pilot study. The results, however, do give some indication of the relative use of Hanks Marsh by sucker and non-sucker species. Through sampling of larval and juvenile suckers in various habitat types within the marsh, we determined that sucker use of Hanks Marsh may be very low in comparison with other areas of the lake. We caught only 42 larval and 19 juvenile suckers during 12 weeks of sampling throughout the marsh. Sucker catches were rare in Hanks Marsh, and were lower than catch rates in other marshes of Upper Klamath Lake and in other nearshore and offshore areas of the lake. Based on the few suckers we did capture in Hanks Marsh, larvae tended to be found more often in vegetated habitats. A modified sampling design and approach may be necessary to address the objectives in this study, given that declining lake-surface elevation prevented us from adequately sampling all portions of the marsh throughout the sampling season. Common non-sucker species in Hanks Marsh included juvenile and adult brown bullhead, larval blue chub, tui chub, fathead minnow, and yellow perch. This species composition was similar to that of other marshes in Upper Klamath Lake but most species were found in lower numbers in Hanks Marsh than other marshes. It may be that use of Hanks Marsh is limited by poor water quality, which we found to exist at many sites after June. It also may be that access to or habitat in the marsh is limited at certain times of the year by low water. Although the results from this initial study of Hanks Marsh indicate that the area may have little direct benefit for sucker species, indirect benefits for these species possibly may come from its positive influence on some aspects of water quality in the lake, such as regulation of pH. It also may be the case that use of Hanks Marsh may vary by year and conditions; however, under the current scope of the study, we were unable to investigate inter-annual variability.

  9. QED and string theory

    NASA Astrophysics Data System (ADS)

    Sugimoto, Shigeki; Takahashi, Kazuyoshi

    2004-04-01

    We analyze the D9-bar Dbar 9 system in type IIB string theory using Dp-brane probes. It is shown that the world-volume theory of the probe Dp-brane contains two-dimensional and four-dimensional QED in the cases with p = 1 and p = 3, respectively, and some applications of the realization of these well-studied quantum field theories are discussed. In particular, the two-dimensional QED (the Schwinger model) is known to be a solvable theory and we can apply the powerful field theoretical techniques, such as bosonization, to study the D-brane dynamics. The tachyon field created by the D9-bar Dbar 9 strings appears as the fermion mass term in the Schwinger model and the tachyon condensation is analyzed by using the bosonized description. In the T-dualized picture, we obtain the potential between a D0-brane and a D8-bar Dbar 8 pair using the Schwinger model and we observe that it consists of the energy carried by fundamental strings created by the Hanany-Witten effect and the vacuum energy due to a cylinder diagram. The D0-brane is treated quantum mechanically as a particle trapped in the potential, which turns out to be a system of a harmonic oscillator. As another application, we obtain a matrix theory description of QED using Taylor's T-duality prescription, which is actually applicable to a wide variety of field theories including the realistic QCD. We show that the lattice gauge theory is naturally obtained by regularizing the matrix size to be finite.

  10. Assessment of Population Status for a White Sucker (Catostomus commersoni) Population Exposed to Bleached Kraft Pulp Mill Effluent

    EPA Science Inventory

    Credible ecological risk assessments often need to include analysis of population-level impacts. In the present study, a predictive model was developed to translate changes in the fecundity and the age structure of a breeding population of white sucker (Catostomus commersoni) co...

  11. Assessment of Population Status for a White Sucker (Catostomus commersoni) Population Exposed to Bleached Kraft Pulp Mill Effluent

    EPA Science Inventory

    A predictive model was developed to translate changes in the fecundity and the age structure of a breeding population of white sucker (Catostomus commersoni) collected in the field to alterations in population growth rate. Application of this density dependent population ...

  12. 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.

  13. 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.

  14. New ambitwistor string theories

    NASA Astrophysics Data System (ADS)

    Casali, Eduardo; Geyer, Yvonne; Mason, Lionel; Monteiro, Ricardo; Roehrig, Kai A.

    2015-11-01

    We describe new ambitwistor string theories that give rise to the recent amplitude formulae for Einstein-Yang-Mills, (Dirac)-Born-Infeld, Galileons and others introduced by Cachazo, He and Yuan. In the case of the Einstein-Yang-Mills amplitudes, an important role is played by a novel worldsheet conformal field theory that provides the appropriate colour factors precisely without the spurious multitrace terms of earlier models that had to be ignored by hand. This is needed to obtain the correct multitrace terms that arise when Yang-Mills is coupled to gravity.

  15. Nonsingular global string compactifications

    PubMed

    Gregory

    2000-03-20

    We consider an exotic "compactification" of spacetime in which there are two infinite extra dimensions, using a global string instead of a domain wall. By having a negative cosmological constant we prove the existence of a nonsingular static solution using a dynamical systems argument. A nonsingular solution also exists in the absence of a cosmological constant with a time-dependent metric. We compare and contrast this solution with the Randall-Sundrum universe and the Cohen-Kaplan spacetime and consider the options of using such a model as a realistic resolution of the hierarchy problem. PMID:11017270

  16. Spawning migration movements of Lost River and shortnose suckers in the Williamson and Sprague Rivers, Oregon, following the removal of Chiloquin Dam-2009 Annual Report

    USGS Publications Warehouse

    Ellsworth, Craig M.; VanderKooi, Scott P.

    2011-01-01

    The Chiloquin Dam was located at river kilometer (rkm) 1.3 on the Sprague River near the town of Chiloquin, Oregon. The dam was identified as a barrier that potentially inhibited or prevented the upstream spawning migrations and other movements of endangered Lost River suckers (Deltistes luxatus), shortnose suckers (Chasmistes brevirostris), and other fish in the Sprague River. Our research objectives in 2009 were to evaluate adult catostomid spawning migration patterns using radio telemetry to identify and describe shifts in spawning area distribution and migration behavior following the removal of Chiloquin Dam in 2008. We attached external radio transmitters to 58 Lost River suckers and 59 shortnose suckers captured at the Williamson River fish weir. A total of 17 radio-tagged Lost River suckers and one radio-tagged shortnose sucker were detected approaching the site of the former Chiloquin Dam but only two radio-tagged fish (one male Lost River sucker and one female Lost River sucker) were detected crossing upstream of the dam site. A lower proportion of radio-tagged shortnose suckers were detected migrating into the Sprague River when compared with previous years. Detections on remote passive integrated transponder (PIT) tag arrays located in the Sprague River show that although the proportion of fish coming into the Sprague River is small when compared to the number of fish crossing the Williamson River fish weir, the number of fish migrating upstream of the Chiloquin Dam site increased exponentially in the first year since its removal. These data will be used in conjunction with larval production and adult spawning distribution data to evaluate the effectiveness of dam removal in order to provide increased access to underutilized spawning habitat located further upstream in the Sprague River and to reduce the crowding of spawning fish below the dam site.

  17. 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

  18. Radially stabilized inflating cosmic strings

    NASA Astrophysics Data System (ADS)

    Niedermann, Florian; Schneider, Robert

    2015-03-01

    In general relativity, local cosmic strings are well known to produce a static, locally flat spacetime with a wedge removed. If the tension exceeds a critical value, the deficit angle becomes larger than 2 ? , leading to a compact exterior that ends in a conical singularity. In this paper, we investigate dynamical solutions for cosmic strings with super-critical tensions. To this end, we model the string as a cylindrical shell of finite and stabilized transverse width and show that there is a marginally super-critical regime in which the stabilization can be achieved by physically reasonable matter. We show numerically that the static deficit angle solution is unstable for super-critical string tensions. Instead, the geometry starts expanding in the axial direction at an asymptotically constant rate, and a horizon is formed in the exterior spacetime, which has the shape of a growing cigar. We are able to find the analytic form of the attractor solution describing the interior of the cosmic string. In particular, this enables us to analytically derive the relation between the string tension and the axial expansion rate. Furthermore, we show that the exterior conical singularity can be avoided for dynamical solutions. Our results might be relevant for theories with two extra dimensions, modeling our Universe as a cosmic string with a three-dimensional axis. We derive the corresponding Friedmann equation, relating the on-brane Hubble parameter to the string tension or, equivalently, brane cosmological constant.

  19. Tadpole resummations in string theory

    NASA Astrophysics Data System (ADS)

    Kitazawa, Noriaki

    2008-02-01

    While R-R tadpoles should be canceled for consistency, string models with broken supersymmetry generally have uncanceled NS-NS tadpoles. Their presence signals that the background does not solve the field equations, so that these models are in "wrong" vacua. In this Letter we investigate, with reference to some prototype examples, whether the true values of physical quantities can be recovered resumming the NS-NS tadpoles, hence by an approach that is related to the analysis based on String Field Theory by open-closed duality. We show that, indeed, the positive classical vacuum energy of a Dp-brane of the bosonic string is exactly canceled by the negative contribution arising from tree-level tadpole resummation, in complete agreement with Sen's conjecture on open-string tachyon condensation and with the consequent analysis based on String Field Theory. We also show that the vanishing classical vacuum energy of the SO(8192) unoriented bosonic open-string theory does not receive any tree-level corrections from the tadpole resummation. This result is consistent with the fact that this (unstable) configuration is free from tadpoles of massless closed-string modes, although there is a tadpole of the closed string tachyon. The application of this method to superstring models with broken supersymmetry is also discussed.

  20. Beats on a vibrating string

    NASA Astrophysics Data System (ADS)

    Larson, James H.

    1999-09-01

    I showed Derrick Boucher's acoustic demonstration of beats and interference to a colleague, and as we were talking I mentioned that the function generator could be hooked to mechanical wave drivers to obtain nice standing waves. Then it's possible to verify that law of vibrating strings. However, we kept coming back to the concept of beats. Could we "see" beats on strings?

  1. 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.

  2. 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…

  3. N-loop string amplitude

    SciTech Connect

    Mandelstam, S.

    1986-06-01

    Work on the derivation of an explicit perturbation series for string and superstring amplitudes is reviewed. The light-cone approach is emphasized, but some work on the Polyakov approach is also mentioned, and the two methods are compared. The calculation of the measure factor is outlined in the interacting-string picture. (LEW)

  4. 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.

  5. 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

  6. Hazard assessment of selenium and other trace elements in wild larval razorback sucker from the Green River, Utah

    USGS Publications Warehouse

    Hamilton, S.J.; Muth, R.T.; Waddell, B.; May, T.W.

    2000-01-01

    Contaminant investigations of the Green River in northeastern Utah have documented selenium contamination at sites receiving irrigation drainage. The Green River provides critical habitat for four endangered fishes including the largest extant riverine population of endangered razorback sucker. Although 2175 larval razorback suckers were collected from the river between 1992 and 1996, very few juveniles have been captured within recent decades. Selenium concentrations were measured in larval razorback suckers collected from five sites in the Green River (Cliff Creek, Stewart Lake Drain, Sportsman's Drain, Greasewood Corral, and Old Charlie Wash) to assess the potential for adverse effects on recruitment of larvae to the juvenile stage and the adult population. Larvae from all sites contained mean selenium concentrations ranging from 4.3 to 5.8 ??g/g. These values were at or above the proposed toxic threshold of 4 ??g/g for adverse biological effects in fish, which was derived from several laboratory and field studies with a wide range of fish species. At two sites, Cliff Creek and Stewart Lake Drain, selenium concentrations in larvae increased over time as fish grew, whereas selenium concentrations decreased as fish grew at Sportsman's Drain. Evaluation of a 279-larvae composite analyzed for 61 elements demonstrated that selenium and, to a lesser extent, vanadium were elevated to concentrations reported to be toxic to a wide range of fish species. Elevated selenium concentrations in larval razorback suckers from the five sites suggest that selenium contamination may be widespread in the Green River, and that survival and recruitment of larvae to the juvenile stage may be limited due to adverse biological effects. Selenium contamination may be adversely affecting the reproductive success and recruitment of endangered razorback sucker.

  7. Characterization of plasma vitellogenin and sex hormone concentrations during the annual reproductive cycle of the endangered razorback sucker

    USGS Publications Warehouse

    Hinck, Jo Ellen; Papoulias, Diana M.; Annis, Mandy L.; Tillitt, Donald E.; Marr, Carrie; Denslow, Nancy D.; Kroll, Kevin J.; Nachtmann, Jason

    2011-01-01

    Population declines of the endangered razorback sucker Xyrauchen texanus in the Colorado River basin have been attributed to predation by and competition with nonnative fishes, habitat alteration, and dam construction. The reproductive health and seasonal variation of the reproductive end points of razorback sucker populations are currently unknown. Using nonlethal methods, we characterized the plasma hormonal fluctuations of reproductively mature female and male razorback suckers over a 12-month period in a hatchery by measuring their vitellogenin (VTG) and three sex hormones: 17β-estradiol (E2), testosterone (T), and 11-ketotestosterone (KT). Fish were identified as reproductive or nonreproductive based on their body weight, VTG, and sex hormone profiles. In reproductive females, the E2 concentration increased in the fall and winter, and increases in T and VTG concentrations were generally associated with the spawning period. Mean T concentrations were consistently greater in reproductive females than in nonreproductive females, but this pattern was even more pronounced during the spawning period (spring). Consistently low T concentrations (<3 ng/mL) in adult females during the spawning period may indicate reproductive impairment. In reproductive males, spring increases in KT and T concentrations were associated with spawning; concentrations of E2 (<0.48 ng/mL) and VTG (<0.001 mg/mL) were low in males throughout the study. In addition, the E2 : KT ratio and T were the best metrics by which to distinguish female from male adult razorback suckers throughout the year. These metrics of reproductive health and condition may be particularly important to recovery efforts of razorback suckers given that the few remaining wild populations are located in a river where water quality and quantity issues are well documented. In addition to the size, age, and recruitment information currently considered in the recovery goals of this endangered species, reproductive end points could be included as recovery metrics with which to monitor seasonal trends and determine whether repatriated populations are cycling naturally.

  8. Field theory for string fluids

    NASA Astrophysics Data System (ADS)

    Schubring, Daniel; Vanchurin, Vitaly

    2015-08-01

    We develop a field theory description of nondissipative string fluids and construct an explicit mapping between field theory degrees of freedom and hydrodynamic variables. The theory generalizes both a perfect particle fluid and pressureless string fluid to what we call a perfect string fluid. Ideal magnetohydrodynamics is shown to be an example of the perfect string fluid whose equations of motion can be obtained from a particular choice of the Lagrangian. The Lagrangian framework suggests a straightforward extension of the perfect string fluid to more general anisotropic fluids describing higher dimensional branes such as domain walls. Other modifications of the Lagrangian are discussed which may be useful in describing relativistic superfluids and fluids containing additional currents.

  9. 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.

  10. 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.

  11. 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.

  12. 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].

  13. 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.

  14. 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].

  15. Estimating geographic variation on allometric growth and body condition of Blue Suckers with quantile regression

    USGS Publications Warehouse

    Cade, B.S.; Terrell, J.W.; Neely, B.C.

    2011-01-01

    Increasing our understanding of how environmental factors affect fish body condition and improving its utility as a metric of aquatic system health require reliable estimates of spatial variation in condition (weight at length). We used three statistical approaches that varied in how they accounted for heterogeneity in allometric growth to estimate differences in body condition of blue suckers Cycleptus elongatus across 19 large-river locations in the central USA. Quantile regression of an expanded allometric growth model provided the most comprehensive estimates, including variation in exponents within and among locations (range = 2.88–4.24). Blue suckers from more-southerly locations had the largest exponents. Mixed-effects mean regression of a similar expanded allometric growth model allowed exponents to vary among locations (range = 3.03–3.60). Mean relative weights compared across selected intervals of total length (TL = 510–594 and 594–692 mm) in a multiplicative model involved the implicit assumption that allometric exponents within and among locations were similar to the exponent (3.46) for the standard weight equation. Proportionate differences in the quantiles of weight at length for adult blue suckers (TL = 510, 594, 644, and 692 mm) compared with their average across locations ranged from 1.08 to 1.30 for southern locations (Texas, Mississippi) and from 0.84 to 1.00 for northern locations (Montana, North Dakota); proportionate differences for mean weight ranged from 1.13 to 1.17 and from 0.87 to 0.95, respectively, and those for mean relative weight ranged from 1.10 to 1.18 and from 0.86 to 0.98, respectively. Weights for fish at longer lengths varied by 600–700 g within a location and by as much as 2,000 g among southern and northern locations. Estimates for the Wabash River, Indiana (0.96–1.07 times the average; greatest increases for lower weights at shorter TLs), and for the Missouri River from Blair, Nebraska, to Sioux City, Iowa (0.90–1.00 times the average; greatest decreases for lower weights at longer TLs), were examined in detail to explain the additional information provided by quantile estimates.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. Lethal levels of selected water quality variables to larval and juvenile Lost River and shortnose suckers

    USGS Publications Warehouse

    Saiki, M.K.; Monda, D.P.; Bellerud, B.L.

    1999-01-01

    Resource managers hypothesize that occasional fish kills during summer-early fall in Upper Klamath Lake, Oregon, may be linked to unfavorable water quality conditions created by massive algal blooms. In a preliminary effort to address this concern, short-term (96-h-long) laboratory tests were conducted with larval and juvenile Lost River (Deltistes luxatus) and shortnose (Chasmistes brevirostris) suckers to determine the upper median lethal concentrations (LC50s; also referred to as median tolerance limits) for pH, un-ionized ammonia, and water temperature, and the lower LC50s for dissolved oxygen. The mean LC50s varied among species and life stages as follows: for pH, 10.30-10.39; for un-ionized ammonia, 0.48-1.06 mg litre-1; for temperature, 30.35-31.82??C; and for dissolved oxygen, 1.34-2.10 mg litre-1. Comparisons of 95% confidence limits indicated that, on average, the 96-h LC50s were not significantly different from those computed for shorter exposure times (i.e., 24 h, 48 h, and 72 h). According to two-way analysis of variance, LC50s for the four water quality variables did not vary significantly (p > 0.05) between fish species. However, LC50s for pH (exposure times of 24 h and 48 h) and dissolved oxygen (exposure times of 48 h, 72 h, and 96 h) differed significantly (p ??? 0.05) between life stages, whereas LC50s for un-ionized ammonia and water temperature did not exhibit significant differences. In general, larvae were more sensitive than juveniles to high pH and low dissolved oxygen concentrations. When compared to ambient water quality conditions in Upper Klamath Lake, our results strongly suggest that near-anoxic conditions associated with the senescence phase of algal blooms are most likely to cause high mortalities of larval and juvenile suckers.

  2. 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.

  3. 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

  4. Observing long cosmic strings through gravitational lensing

    NASA Astrophysics Data System (ADS)

    de Laix, Andrew A.

    1997-11-01

    We consider the gravitational lensing produced by long cosmic strings formed in a grand-unified theory scale phase transition. We derive a formula for the deflection of photons which pass near the strings that reduces to an integral over the light cone projection of the string configuration plus constant terms which are not important for lensing. Our strings are produced by performing numerical simulations of cosmic string networks in flat, Minkowski space ignoring the effects of cosmological expansion. These strings have more small scale structure than those from an expanding universe simulation-fractal dimension 1.3 for Minkowski versus 1.1 for expanding-but share the same qualitative features. Lensing simulations show that for both pointlike and extended objects strings produce patterns unlike more traditional lenses, and, in particluar, the kinks in strings tend to generate demagnified images which reside close to the string. Thus lensing acts as a probe of the small scale structure of a string. Estimates of lensing probablity suggest that for string energy densities consistent with string seeded structure formation, on the order of tens of string lenses should be observed in the Sloan Digital Sky Survey (SDSS) quasar catalog. We propose a search strategy in which string lenses would be identified in the SDSS quasar survey, and the string nature of the lens can be confirmed by the observation of nearby high redshift galaxies which are also be lensed by the string.

  5. 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…

  6. 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.

  7. 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.

  8. Bullfrog tadpole (Rana catesbeiana) and red swamp crayfish (Procambarus clarkii) predation on early life stages of endangered razorback sucker (Xyrauchen texanus)

    USGS Publications Warehouse

    Mueller, G.A.; Carpenter, J.; Thornbrugh, D.

    2006-01-01

    Bullfrog tadpoles (Rana catesbeiana) and red swamp crayfish (Procambarus clarkii) are widespread introduced taxa that are problematic throughout the western United States. Their impact on native amphibians and crustaceans is well documented, but less is known regarding their influence on native fishes. Predator-prey tank tests showed both species consumed eggs and larvae of the endangered razorback sucker (Xyrauchen texanus) in a laboratory setting. Tadpoles consumed 2.2 razorback sucker eggs/d and 1.4 razorback sucker larvae/d, while crayfish ate 6.0 eggs/d and 3.5 larvae/d. Relatively high densities of bullfrog tadpoles and crayfish in razorback sucker spawning areas suggest that these nonnative taxa might pose a threat to the recruitment success of this and other imperiled native fish.

  9. Semisuperfluid strings in high density QCD

    SciTech Connect

    Balachandran, A.P.; Digal, S.; Matsuura, T.

    2006-04-01

    We show that topological semisuperfluid strings exist in the color-flavor locked (CFL) phase of color superconductors. These semisuperfluid strings carry quantized flux of ordinary and color magnetic fields. Away from the core the behavior of the string is that of a superfluid string. Using a Ginzburg-Landau free energy we find the configurations of these strings. These strings can form during the transition from the normal phase to the CFL phase at the core of very dense stars. We discuss an interesting scenario for a network of strings and its evolution at the core of dense stars.

  10. 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.

  11. Poisson hierarchy of discrete strings

    NASA Astrophysics Data System (ADS)

    Ioannidou, Theodora; Niemi, Antti J.

    2016-01-01

    The Poisson geometry of a discrete string in three dimensional Euclidean space is investigated. For this the Frenet frames are converted into a spinorial representation, the discrete spinor Frenet equation is interpreted in terms of a transfer matrix formalism, and Poisson brackets are introduced in terms of the spinor components. The construction is then generalised, in a self-similar manner, into an infinite hierarchy of Poisson algebras. As an example, the classical Virasoro (Witt) algebra that determines reparametrisation diffeomorphism along a continuous string, is identified as a particular sub-algebra, in the hierarchy of the discrete string Poisson algebra.

  12. 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.

  13. Characterization of a Novel Hepadnavirus in the White Sucker (Catostomus commersonii) from the Great Lakes Region of the United States

    PubMed Central

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

    2015-01-01

    ABSTRACT 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 United States. Dideoxy sequencing confirmed that the white sucker hepatitis B virus (WSHBV) has a circular genome (3,542 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 to 27% at the amino acid level. An X protein homologue common to the orthohepadnaviruses was not present. The WSHBV genome included an atypical, presumptively noncoding 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 and 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%, and only 2.4% of fish 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. IMPORTANCE We report the first full-length genome of a hepadnavirus from fishes. Phylogenetic analysis of this genome indicates divergence from genomes of previously described hepadnaviruses from mammalian and avian hosts and supports the creation of a novel genus. The discovery of this novel virus may better our understanding of the evolutionary history of hepatitis B-like viruses of other hosts. In fishes, knowledge of this virus may provide insight regarding possible risk factors associated with hepatic neoplasia in the white sucker. This may also offer another model system for mechanistic research. PMID:26378165

  14. String cosmology — Large-field inflation in string theory

    NASA Astrophysics Data System (ADS)

    Westphal, Alexander

    2015-03-01

    This is a short review of string cosmology. We wish to connect string-scale physics as closely as possible to observables accessible to current or near-future experiments. Our possible best hope to do so is a description of inflation in string theory. The energy scale of inflation can be as high as that of Grand Unification (GUT). If this is the case, this is the closest we can possibly get in energy scales to string-scale physics. Hence, GUT-scale inflation may be our best candidate phenomenon to preserve traces of string-scale dynamics. Our chance to look for such traces is the primordial gravitational wave, or tensor mode signal produced during inflation. For GUT-scale inflation this is strong enough to be potentially visible as a B-mode polarization of the cosmic microwave background (CMB). Moreover, a GUT-scale inflation model has a trans-Planckian excursion of the inflaton scalar field during the observable amount of inflation. Such large-field models of inflation have a clear need for symmetry protection against quantum corrections. This makes them ideal candidates for a description in a candidate fundamental theory like string theory. At the same time the need of large-field inflation models for UV completion makes them particularly susceptible to preserve imprints of their string-scale dynamics in the inflationary observables, the spectral index ns and the fractional tensor mode power r. Hence, we will focus this review on axion monodromy inflation as a mechanism of large-field inflation in string theory.

  15. String Cosmology -- Large-Field Inflation in String Theory

    NASA Astrophysics Data System (ADS)

    Westphal, Alexander

    2014-12-01

    This is a short review of string cosmology. We wish to connect string-scale physics as closely as possible to observables accessible to current or near-future experiments. Our possible best hope to do so is a description of inflation in string theory. The energy scale of inflation can be as high as that of Grand Unification (GUT). If this is the case, this is the closest we can possibly get in energy scales to string-scale physics. Hence, GUT-scale inflation may be our best candidate phenomenon to preserve traces of string-scale dynamics. Our chance to look for such traces is the primordial gravitational wave, or tensor mode signal produced during inflation. For GUT-scale inflation this is strong enough to be potentially visible as a B-mode polarization of the cosmic microwave background (CMB). Moreover, a GUT-scale inflation model has a trans-Planckian excursion of the inflaton scalar field during the observable amount of inflation. Such large-field models of inflation have a clear need for symmetry protection against quantum corrections. This makes them ideal candidates for a description in a candidate fundamental theory like string theory. At the same time the need of large-field inflation models for UV completion makes them particularly susceptible to preserve imprints of their string-scale dynamics in the inflationary observables, the spectral index ns and the fractional tensor mode power r. Hence, we will focus this review on axion monodromy inflation as a mechanism of large-field inflation in string theory.

  16. 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.

  17. Cosmic string catalysis of skyrmion decay

    SciTech Connect

    Gregory, R.; Davis, A.C.; Brandenberger, R.

    1988-10-01

    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.

  18. Charting the Landscape of Supercritical String Theory

    SciTech Connect

    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.

  19. 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.

  20. 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.

  1. 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.

  2. Ecological effects of a single intraperitoneal injection of [{sup 14}C]-2,3,4,7,8-pentachlorodibenzofuran on feral populations of lake trout and white suckers

    SciTech Connect

    Delorme, P.D.; Lockhart, W.L.; Muir, D.C.G.; Mills, K.H.; Brown, S.B.

    1994-12-31

    In 1989 a total of 24 lake trout and 35 white suckers from a small lake located in the Experimental Lakes Area (ELA) in northwestern Ontario were each targeted with an I.P. injection of [{sup 14}C]-s,3,4,7,8-pentachlorodibenzofuran in corn oil, to a dose of 1 ng{center_dot}g{sup {minus}1}. Fish were tagged, returned to the lake and recaptured during spawning runs in 1990, 1991 and 1992. Sub-samples of treated and control fish were sacrificed each year for residue and biochemical analyses. Treated females were spawned in 1990 and 1991. Analysis of tag-recapture data showed lower survival of treated lake trout over four years. Growth was significantly lower in white suckers in all years but unaffected in lake trout. Fertilization rate of eggs was lower in eggs from treated female white suckers, but not in lake trout. However, only 1 of 4 treated female lake trout recaptured had undergone oogenesis in the last two years of recaptures. Measurements of EROD showed sustained induction in both lake trout and white suckers. Hepatic levels of retinoids were significantly decreased in lake trout but not in white suckers. Calculated half-lives of P{sub 5}CDF were 9.6 years for lake trout and 4.3 years for white suckers. It appears that long term ecological performance was impaired in both species.

  3. 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

  4. Gauge invariance of string fields

    NASA Astrophysics Data System (ADS)

    Banks, Thomas; Peskin, Michael E.

    1986-01-01

    We identify the gauge invariances of the linearized field theory of strings which give rise to the Yang-Mills and general coordinate invariance of this theory. We construct a kinetic energy term for string fields which is invariant to these gauge symmetries. By gauge-fixing, we derive from this action the expressions for the free string action, in particular gauges found by Kaku and Kikkawa and by Siegel. The structure of Stueckelberg auxilliary fields required to make the gauge-invariant action local is rather intricate; to clarify this structure, we develop a theory of differential forms on the space of strings. We conclude with some remarks on the origin of the dilaton and the appearance in the superstring of local supersymmetry.

  5. From String Nets to Nonabelions

    NASA Astrophysics Data System (ADS)

    Fidkowski, Lukasz; Freedman, Michael; Nayak, Chetan; Walker, Kevin; Wang, Zhenghan

    2009-05-01

    We discuss Hilbert spaces spanned by the set of string nets, i.e. trivalent graphs, on a lattice. We suggest some routes by which such a Hilbert space could be the low-energy subspace of a model of quantum spins on a lattice with short-ranged interactions. We then explain conditions which a Hamiltonian acting on this string net Hilbert space must satisfy in order for the system to be in the DFib (Doubled Fibonacci) topological phase, that is, be described at low energy by an SO(3)3 SO(3)3 doubled Chern-Simons theory, with the appropriate non-abelian statistics governing the braiding of the low-lying quasiparticle excitations (nonabelions). Using the string net wavefunction, we describe the properties of this phase. Our discussion is informed by mappings of string net wavefunctions to the chromatic polynomial and the Potts model.

  6. 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)

  7. 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

    2015-01-01

    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

  8. 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.

  9. 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 ?RR between rod blocks, lengths of rod and coil blocks in copolymer, and mixture ratio of block copolymers to homopolymers. As the ?RR 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

  10. Reactor control rod timing system

    DOEpatents

    Wu, Peter T. K. (Clifton Park, NY)

    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.

  11. 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; Lst, 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 ? +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 ?5? in dijet (? +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-brane string compactifications. Our calculations have been performed using a semianalytic parton model approach which is cross checked against an original software package. The string event generator interfaces with HERWIG and Pythia through BlackMax. The source code is publicly available in the hepforge repository.

  12. Aspects of topological string theory

    NASA Astrophysics Data System (ADS)

    Cook, Paul L. H.

    Two aspects of the topological string and its applications are considered in this thesis. Firstly, non-perturbative contributions to the OSV conjecture relating four-dimensional extremal black holes and the closed topological string partition function are studied. A new technique is formulated for encapsulating these contributions for the case of a Calabi-Yau manifold constructed by fibering two line bundle over a torus, with the unexpected property that the resulting non-perturbative completion of the topological string partition function is such that the black hole partition function is equal to a product of a chiral and an anti-chiral function. This new approach is considered both in the context of the requirement of background independence for the topological string, and for more general Calabi-Yau manifolds. Secondly, this thesis provides a microscopic derivation of the open topological string holomorphic anomaly equations proposed by Walcher in arXiv:0705.4098 under the assumption that open string moduli do not contribute. In doing so, however, new anomalies are found for compact Calabi-Yau manifolds when the disk one-point functions (string to boundary amplitudes) are non-zero. These new anomalies introduce coupling to wrong moduli (complex structure moduli in A-model and Kahler moduli in B-model), and spoil the recursive structure of the holomorphic anomaly equations. For vanishing disk one-point functions, the open string holomorphic anomaly equations can be integrated to solve for amplitudes recursively, using a Feynman diagram approach, for which a proof is presented.

  13. 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.

  14. Automatic safety rod for reactors

    DOEpatents

    Germer, John H. (San Jose, CA)

    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.

  15. Towards a nonsupersymmetric string phenomenology

    NASA Astrophysics Data System (ADS)

    Abel, Steven; Dienes, Keith R.; Mavroudi, Eirini

    2015-06-01

    Over the past three decades, considerable effort has been devoted to studying the rich and diverse phenomenologies of heterotic strings exhibiting spacetime supersymmetry. Unfortunately, during this same period, there has been relatively little work studying the phenomenologies associated with their nonsupersymmetric counterparts. The primary reason for this relative lack of attention is the fact that strings without spacetime supersymmetry are generally unstable, exhibiting large one-loop dilaton tadpoles. In this paper, we demonstrate that this hurdle can be overcome in a class of tachyon-free four-dimensional string models realized through coordinate-dependent compactifications. Moreover, as we shall see, it is possible to construct models in this class whose low-lying states resemble the Standard Model (or even potential unified extensions thereof)all without any light superpartners, and indeed without supersymmetry at any energy scale. The existence of such models thus opens the door to general studies of nonsupersymmetric string phenomenology, and in this paper we proceed to discuss a variety of theoretical and phenomenological issues associated with such nonsupersymmetric strings. On the theoretical side, we discuss the finiteness properties of such strings, the general characteristics of their mass spectra, the magnitude and behavior of their one-loop cosmological constants, and their interpolation properties. By contrast, on the phenomenological side, the properties we discuss are more model-specific and include their construction techniques, their natural energy scales, their particle and charge assignments, and the magnitudes of their associated Yukawa couplings and scalar masses.

  16. Quantum string seal is insecure

    NASA Astrophysics Data System (ADS)

    Chau, H. F.

    2007-01-01

    A quantum string seal encodes the value of a (bit) string as a quantum state in such a way that everyone can extract a non-negligible amount of available information on the string by a suitable measurement. Moreover, such measurement must disturb the quantum state and is likely to be detected by an authorized verifier. In this way, the intactness of the encoded quantum state plays the role of a wax seal in the digital world. Here we analyze the security of quantum string seal by studying the information disturbance trade-off of a measurement. This information disturbance trade-off analysis extends the earlier results of Bechamann-Pasquinucci, D’Ariano, and Macchiavello [Int. J. Quant. Inform. 3, 435 (2005)] and Chau [Phys. Lett. A 354, 31 (2006)] by concluding that all quantum string seals are insecure. Specifically, we find a way to obtain nontrivial available information on the string that escapes the verifier’s detection with at least 50% chance.

  17. Demographics and Chronology of a Spawning Aggregation of Blue Sucker (Cycleptus elongatus) in the Grand River, Missouri, USA

    USGS Publications Warehouse

    Vokoun, J.C.; Guerrant, T.L.; Rabeni, C.F.

    2003-01-01

    The blue sucker (Cycleptus elongatus) was sampled as individuals arrived, spawned, and departed from a spawning riffle in the Grand River of northcentral Missouri, USA. The Grand River basin was not known to support blue sucker reproduction with few individuals ever recorded. The spawning site is unique in character for the lower river. Individuals began arriving in early April when water temperatures reached 10-12??C. Females with freely-flowing roe were sampled in late April after a large rise in river stage and concurrent lowering of the water temperature 4-5 degrees to 16.5??C. The spawning aggregation had a mean age of 15 y and ranged from 9 to 22 y based on scales that probably underestimated true ages. Males outnumbered females 5.5:1. Mean length was 659 mm for males and 721 mm for females. Females were longer at age than males and no significant age-length relationship was evident.

  18. 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.

  19. Self-assembly behavior of ABA coil-rod-coil triblock copolymers: A Brownian dynamics simulation approach

    NASA Astrophysics Data System (ADS)

    Li, Yongliang; Lin, Shaoliang; He, Xiaohua; Lin, Jiaping; Jiang, Tao

    2011-07-01

    The self-assembly behavior of ABA coil-rod-coil triblock copolymers in a selective solvent was studied by a Brownian molecular dynamics simulation method. It was found that the rod midblock plays an important role in the self-assembly of the copolymers. With a decrease in the segregation strength, ?RR, of rod pairs, the aggregate structure first varies from a smecticlike disk shape to a long twisted string micelle and then to small aggregates. The influence of the block length and the asymmetry of the triblock copolymer on the phase behavior were studied and the corresponding phase diagrams were mapped. It was revealed that the variation of these parameters has a profound effect on microstructure. The simulation results are consistent with experimental results. Compared to rod-coil diblock copolymers, the coil-rod-coil triblock copolymers has a larger entropy penalty associated with the interfacial grafting density of the aggregate, leading to a higher ?RR value for structural transitions.

  20. Chemical and Ecological Health of White Sucker (Catostomus Commersoni) in Rock Creek Park, Washington, D.C., 2003-04

    USGS Publications Warehouse

    Miller, Cherie V.; Weyers, Holly S.; Blazer, Vicki; Freeman, Mary E.

    2006-01-01

    Several classes of chemicals that are known or suspected contaminants were found in bed sediment in Rock Creek, including polyaromatic hydrocarbons (PAHs), phthalate esters, organochlorine pesticides, dioxins and furans, trace metals and metalloids (mercury, arsenic, cadmium, chromium, cobalt, copper, lead, nickel, silver, and zinc), and polychlorinated biphenyls (total PCBs and selected aroclors). Concentrations of many of these chemicals consistently exceeded threshold or chronic-effects guidelines for the protection of aquatic life and often exceeded probable effects levels (PELs). Exceedance of PELs was dependent on the amount of total organic carbon in the sediments. Concurrent with the collection of sediment-quality data, white sucker (Catostomus commersoni) were evaluated for gross-external and internal-organ anomalies, whole-body burdens of chemical contaminants, and gut contents to determine prey. The histopathology of internal tissues of white sucker was compared to contaminant levels in fish tissue and bed sediment. Gut contents were examined to determine preferential prey and thus potential pathways for the bioaccumulation of chemicals from bed sediments. Male and female fish were tested separately. Lesions and other necroses were observed in all fish collected during both years of sample collection, indicating that fish in Rock Creek have experienced some form of environmental stress. No direct cause and effect was determined for chemical exposure and compromised fish health, but a substantial weight of evidence indicates that white sucker, which are bottom-feeding fish and low-order consumers in Rock Creek, are experiencing some reduction in vitality, possibly due to immunosuppression. Abnormalities observed in gonads of both sexes of white sucker and observations of abnormal behavior during spawning indicated some interruption in reproductive success.

  1. Chemical and ecological health of white sucker (Catostomus Commersoni) in Rock Creek Park, Washington, D.C., 2003?04

    USGS Publications Warehouse

    Miller, C.V.; Weyers, H.S.; Blazer, V.S.; Freeman, M.E.

    2006-01-01

    Several classes of chemicals that are known or suspected contaminants were found in bed sediment in Rock Creek, including polyaromatic hydrocarbons (PAHs), phthalate esters, organochlorine pesticides, dioxins and furans, trace metals and metalloids (mercury, arsenic, cadmium, chromium, cobalt, copper, lead, nickel, silver, and zinc), and polychlorinated biphenyls (total PCBs and selected aroclors). Concentrations of many of these chemicals consistently exceeded thresholdor chronic-effects guidelines for the protection of aquatic life and often exceeded probable effects levels (PELs). Exceedance of PELs was dependent on the amount of total organic carbon in the sediments. Concurrent with the collection of sediment-quality data, white sucker (Catostomus commersoni) were evaluated for gross-external and internal-organ anomalies, whole-body burdens of chemical contaminants, and gut contents to determine prey. The histopathology of internal tissues of white sucker was compared to contaminant levels in fish tissue and bed sediment. Gut contents were examined to determine preferential prey and thus potential pathways for the bioaccumulation of chemicals from bed sediments. Male and female fish were tested separately. Lesions and other necroses were observed in all fish collected during both years of sample collection, indicating that fish in Rock Creek have experienced some form of environmental stress. No direct cause and effect was determined for chemical exposure and compromised fish health, but a substantial weight of evidence indicates that white sucker, which are bottom-feeding fish and low-order consumers in Rock Creek, are experiencing some reduction in vitality, possibly due to immunosuppression. Abnormalities observed in gonads of both sexes of white sucker and observations of abnormal behavior during spawning indicated some interruption in reproductive success.

  2. Spawning ecology of flannelmouth sucker, Catostomus lattipinnis (Catostomidae), in two small tributaries of the lower Colorado river

    USGS Publications Warehouse

    Weiss, S.J.; Otis, E.O.; Maughan, O.E.

    1998-01-01

    We report the first published accounts of spawning behavior and spawning site selection of the flannelmouth sucker in two small tributaries of the lower Colorado River in the Grand Canyon, Arizona. Spawning was observed on 20 March 1992 and from 28 March to 10 April 1993 in the Paria River, and from 16 to 19 March 1993 in Bright Angel Creek. Flannelmouth suckers exhibited promiscuous spawning behavior-individual females were typically paired with two or more males for a given event and sometimes changed partners between events. Multiple egg deposits by different females sometimes occurred at one spawning site. Flannelmouth sucker selected substrates from 16 to 32 mm diameter in both streams. Spawning occurred at depths of 10 to 25 cm in the Paria River and 19 to 41 cm in Bright Angel Creek. Mean column water velocities at spawning locations ranged from 0.15 to 1.0 m sec-1 in the Paria River and from 0.23 to 0.89 m sec-1 in Bright Angel Creek. Water temperatures recorded during spawning ranged from 9 to 18??C in the Paria River and 13 to 15??C in Bright Angel Creek. Spawning flannelmouth sucker ascended 9.8 km upstream in the Paria River and 1.25 km in Bright Angel Creek. Spawning females (410-580 mm) were significantly larger than spawning males (385-530 mm) in the Paria River. The mean size of spawning fish in the Paria River was significantly smaller than the entire stock, averaged throughout the study period (380-620 mm). However, fish spawning in 1992-1993 averaged 53 mm larger than fish spawning in the same reach of the Paria River in 1981, indicating a shift in the size structure of this stock.

  3. Tag loss and short-term mortality associated with passive integrated transponder tagging of juvenile Lost River suckers

    USGS Publications Warehouse

    Burdick, Summer M.

    2011-01-01

    Passive integrated transponder (PIT) tags are commonly used to mark small catostomids, but tag loss and the effect of tagging on mortality have not been assessed for juveniles of the endangered Lost River sucker Deltistes luxatus. I evaluated tag loss and short-term (34-d) mortality associated with the PIT tagging of juvenile Lost River suckers in the laboratory by using a completely randomized design and three treatment groups (PIT tagged, positive control, and control). An empty needle was inserted into each positive control fish, whereas control fish were handled but not tagged. Only one fish expelled its PIT tag. Mortality rate averaged 9.8 3.4% (mean SD) for tagged fish; mortality was 0% for control and positive control fish. All tagging mortalities occurred in fish with standard lengths of 71 mm or less, and most of the mortalities occurred within 48 h of tagging. My results indicate that 12.45- 2.02-mm PIT tags provide a viable method of marking juvenile Lost River suckers that are 72 mm or larger.

  4. Spawning by walleye (Sander vitreus) and white sucker (Catostomus commersoni) in the Detroit River: Implications for spawning habitat enhancement

    USGS Publications Warehouse

    Manny, B.A.; Kennedy, G.W.; Boase, J.C.; Allen, J.D.; Roseman, E.F.

    2010-01-01

    Few active fish spawning grounds have been found in channels connecting the Great Lakes. Here, we describe one near Belle Isle in the Detroit River, part of the channel connecting lakes Huron and Erie. There, in 2005, we collected 1,573 fish eggs, cultured them, and identified the hatched larvae as walleye (Sander vitreus) and white sucker (Catostomus commersoni). Walleye spawning peaked during the week of April 12-19; white sucker spawning peaked on May 10. Average areal rate of egg deposition by walleye and white sucker at this spawning ground in 2005 was 346 and 25 eggs/m2, respectively. Our environmental measurements showed that bottom substrates on this spawning ground were largely sand, not optimal for fish reproduction. We hypothesize that reproduction of these fish at this spawning ground could be enhanced by adding rock and gravel substrates for protection of deposited fish eggs and suggest that reproduction by walleye in the Detroit River may add resilience to production of walleye in western Lake Erie. ?? 2010.

  5. Milt characteristics, reproductive performance, and larval survival and development of white sucker exposed to bleached kraft mill effluent

    SciTech Connect

    McMaster, M.E.; Portt, C.B.; Munkittrick, K.R.; Dixon, D.G. )

    1992-02-01

    White sucker from a Lake Superior bay which receives bleached kraft mill effluent (BKME) show increased hepatic mixed-function oxygenase (MFO) activity, reduced plasma sex steroid levels, decreased egg and gonad size, a decrease in the occurrence of secondary sexual characteristics, and an increased age to maturation. This study evaluated the reproductive performance of that white sucker population relative to a similar reference population. Spawning male white sucker from the BKME site had reduced spermatozoan motility but no significant differences in milt volume, spermatocrit levels, or seminal plasma constituents. BKME male and female fish had equal or greater fertilization potential compared to both male and female fish at the reference site. There was no difference either in the hatchability of the eggs or in larval size at hatch. BKME larvae did show reduced growth rates by 24 days posthatch but showed equal rates of yolk utilization. No difference in larval MFO activity was detected between sites at 21 days posthatch, indicating no parental transfer of induction to the progeny.

  6. 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

  7. Threading plasmonic nanoparticle strings with light.

    PubMed

    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 122?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

  8. Collisions of Strings with Y Junctions

    NASA Astrophysics Data System (ADS)

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

    2006-07-01

    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.

  9. 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

  10. Composite Lightning Rods for Aircraft

    NASA Technical Reports Server (NTRS)

    Bryan, Charles F., Jr.

    1986-01-01

    Composite, lightweight sacrificial tip with graphite designed reduces lightning-strike damage to composite parts of aircraft and dissipates harmful electrical energy. Device consists of slender composite rod fabricated from highly-conductive unidirectional reinforcing fibers in matrix material. Rods strategically installed in trailing edges of aircraft wings, tails, winglets, control surfaces, and rearward-most portion of aft fuselage.

  11. Experiments with a falling rod

    NASA Astrophysics Data System (ADS)

    Oliveira, Vitor

    2016-02-01

    We study the motion of a uniform thin rod released from rest, with the bottom end initially in contact with a horizontal surface. Our focus here is the motion of the bottom end as the rod falls. For small angles of release with respect to the horizontal, the rod falls without the bottom end slipping. For larger angles, the slipping direction depends on the static friction coefficient between the rod and the horizontal surface. Small friction coefficients cause the end to slip initially in one direction and then in the other, while for high coefficients, the end slips in one direction only. For intermediate values, depending on the angle of release, both situations can occur. We find the initial slipping direction to depend on a relation between the angle at which the rod slips, and a critical angle at which the frictional force vanishes. Comparison between experimental data and numerical simulations shows good agreement.

  12. Constraints on string networks with junctions

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

    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 1/2, the result for conventional Nambu-Goto strings without junctions in Minkowski space-time.

  13. Cosmoparticle Physics and String Theory

    NASA Astrophysics Data System (ADS)

    Sjrs, Stefan

    This thesis deals with phenomenological and theoretical aspects of cosmoparticle physics and string theory. There are many open questions in these topics. In connection with cosmology we would like to understand the detailed properties of dark matter, dark energy, generation of primordial perturbations, etc., and in connection with particle physics we would like to understand the detailed properties of models that stabilize the electroweak scale, for instance supersymmetry. At the same time, we also need to understand these issues in a coherent theoretical framework. Such a framework is offered by string theory. In this thesis, I analyze the interplay between Higgs and dark matter physics in an effective field theory extension of the minimally supersymmetric standard model. I study a theory of modified gravity, where the graviton has acquired a mass, and show the explicit implementation of the Vainshtein mechanism, which allows one to put severe constraints on the graviton mass. I address the question of Planck scale corrections to inflation in string theory, and show how such corrections can be tamed. I study perturbations of warped throat regions of IIB string theory compactifications and classify allowed boundary conditions. Using this analysis, I determine the potential felt by an anti-D3-brane in such compactifications, using the explicit harmonic data on the conifold. I also address questions of perturbative quantum corrections in string theory and calculate one-loop corrections to the moduli space metric of Calabi-Yau orientifolds.

  14. Quantum stabilization of cosmic strings

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    In the standard model, stabilization of a classically unstable cosmic string may occur through the quantum fluctuations of a heavy fermion doublet. We review numerical results from a semiclassical expansion in a reduced version of the standard model. In this expansion, the leading quantum corrections emerge at one loop level for many internal degrees of freedom. The resulting vacuum polarization energy and the binding energies of occupied fermion energy levels are of the same order, and must therefore be treated on equal footing. Populating these bound states lowers the total energy compared to the same number of free fermions and assigns a charge to the string. Charged strings are already stabilized for a fermion mass only somewhat larger than the top quark mass. Though obtained in a reduced version, these results suggest that neither extraordinarily large fermion masses nor unrealistic couplings are required to bind a cosmic string in the standard model. Furthermore, we also review results for a quantum stabilization mechanism that prevents closed Nielsen-Olesen-type strings from collapsing.

  15. 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.

  16. Nanoconfined ?-sheets mechanically reinforce the supra-biomolecular network of robust squid Sucker Ring Teeth.

    PubMed

    Guerette, Paul A; Hoon, Shawn; Ding, Dawei; Amini, Shahrouz; Masic, Admir; Ravi, Vydianathan; Venkatesh, Byrappa; Weaver, James C; Miserez, Ali

    2014-07-22

    The predatory efficiency of squid and cuttlefish (superorder Decapodiformes) is enhanced by robust Sucker Ring Teeth (SRT) that perform grappling functions during prey capture. Here, we show that SRT are composed entirely of related structural suckerin proteins whose modular designs enable the formation of nanoconfined ?-sheet-reinforced polymer networks. Thirty-seven previously undiscovered suckerins were identified from transcriptomes assembled from three distantly related decapodiform cephalopods. Similarity in modular sequence design and exonintron architecture suggests that suckerins are encoded by a multigene family. Phylogenetic analysis supports this view, revealing that suckerin genes originated in a common ancestor ~350 MYa and indicating that nanoconfined ?-sheet reinforcement is an ancient strategy to create robust bulk biomaterials. X-ray diffraction, nanomechanical, and micro-Raman spectroscopy measurements confirm that the modular design of the suckerins facilitates the formation of ?-sheets of precise nanoscale dimensions and enables their assembly into structurally robust supramolecular networks stabilized by cooperative hydrogen bonding. The suckerin gene family has likely played a key role in the evolutionary success of decapodiform cephalopods and provides a large molecular toolbox for biomimetic materials engineering. PMID:24911543

  17. Time-series analysis reveals genetic responses to intensive management of razorback sucker (Xyrauchen texanus)

    PubMed Central

    Dowling, Thomas E; Turner, Thomas F; Carson, Evan W; Saltzgiver, Melody J; Adams, Deborah; Kesner, Brian; Marsh, Paul C

    2014-01-01

    Time-series analysis is used widely in ecology to study complex phenomena and may have considerable potential to clarify relationships of genetic and demographic processes in natural and exploited populations. We explored the utility of this approach to evaluate population responses to management in razorback sucker, a long-lived and fecund, but declining freshwater fish species. A core population in Lake Mohave (Arizona-Nevada, USA) has experienced no natural recruitment for decades and is maintained by harvesting naturally produced larvae from the lake, rearing them in protective custody, and repatriating them at sizes less vulnerable to predation. Analyses of mtDNA and 15 microsatellites characterized for sequential larval cohorts collected over a 15-year time series revealed no changes in geographic structuring but indicated significant increase in mtDNA diversity for the entire population over time. Likewise, ratios of annual effective breeders to annual census size (Nb/Na) increased significantly despite sevenfold reduction of Na. These results indicated that conservation actions diminished near-term extinction risk due to genetic factors and should now focus on increasing numbers of fish in Lake Mohave to ameliorate longer-term risks. More generally, time-series analysis permitted robust testing of trends in genetic diversity, despite low precision of some metrics. PMID:24665337

  18. Relative sensitivity of three endangered fishes, Colorado squawfish, bonytail, and razorback sucker, to selected metal pollutants

    USGS Publications Warehouse

    Buhl, K.J.

    1997-01-01

    The acute toxicity of four metal pollutants to larval and juvenile stages of endangered Colorado squawfish (Ptychocheilus lucius), bonytail (Gila elegans), and razorback sucker (Xyrauchen texanus) were determined in a water quality representative of that in the Green River, Utah. The rank order of toxicity (96-hr LC50) of the metals to all species and life stages from most toxic to least toxic was mercury (57-168 ??G/liter) > cadmium (78-168 pg/liter) > hexavalent chromium (32,000-123,000 ??g/liter) > lead (>170,000 ??G/liter). In tests with lead, a precipitate formed in all test solutions and no mortalities occurred in these treatments. The larvae of each species were as sensitive or more sensitive than the juveniles to cadmium, hexavalent chromium, and mercury. Overall, the three species exhibited similar sensitivities to cadmium, hexavalent chromium, and mercury. Comparison of test results for the juveniles with toxicity values reported for other freshwater fishes tested in different water qualities indicates that the endangered fishes are more sensitive to cadmium than other cyprinids and centrarchids and less sensitive than salmonids, whereas their sensitivity to hexavalent chromium and mercury is similar to that of other cyprinids, centrarchids, and salmonids.

  19. Effects of ambient water quality on the endangered Lost River sucker in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Martin, B.A.; Saiki, M.K.

    1999-01-01

    Populations of the Lost River sucker Deltistes luxatus have declined so precipitously in the Upper Klamath Basin of Oregon and California that this fish was recently listed for federal protection as an endangered species. Although Upper Klamath Lake is a major refuge for this species, fish in the lake occasionally experience mass mortalities during summer and early fall. This field study was implemented to determine if fish mortalities resulted from degraded water quality conditions associated with seasonal blooms of phytoplankton, especially Aphanizomenon flos-aquae. Our results indicated that fish mortality did not always increase as water temperature, pH, and un-ionized ammonia concentration increased in Upper Klamath Lake. Little or no mortality occurred when these water quality variables attained their maximum values. On the other hand, an inverse relation existed between fish mortality and dissolved oxygen concentration. High mortality (>90%) occurred whenever dissolved oxygen concentrations decreased to 1.05 mg/L, whereas mortality was usually low (< 10%) when dissolved oxygen concentrations equaled or exceeded 1.58 mg/L. Stepwise logistic regression also indicated that the minimum concentration of dissolved oxygen measured was the single most important determinant of fish mortality.

  20. Macroecology of North American suckers (Catostomidae): tests of Bergmann's and Rapoport's rules.

    PubMed

    Jacquemin, Stephen J; Doll, Jason C

    2015-09-01

    Discerning spatial macroecological patterns in freshwater fishes has broad implications for community assembly, ecosystem dynamics, management, and conservation. This study explores the potential interspecific covariation of geographic range (Rapoport's rule) and body size (Bergmann's rule) with latitude in North American sucker fishes (Cypriniformes: Catostomidae). While numerous tests of Rapoport's and Bergmann's rules are documented in the literature, comparatively few of these studies have specifically tested for these patterns, and none have incorporated information reflecting shared ancestry into analyses of North American freshwater fish through a hierarchical model. This study utilized a hierarchical modeling approach with Bayesian inference to evaluate the role that evolution has played in shaping these distributional corollaries. Rapoport's rule was supported at the tribe level but not across family and subfamily groupings. Particularly within the Catostominae subfamily, two tribes reflected strong support for Rapoport's rule while two suggested a pattern was present. Conversely, Bergmann's rule was not supported in Catostomidae. This study provides additional information regarding the pervasiveness of these "rules" by expanding inferences in freshwater fishes and specifically addressing the potential for these macroecological patterns to play a role in the distribution of the understudied group Catostomidae. PMID:26445650

  1. White sucker (Catostomus commersoni) growth and sexual maturation in pulp mill-contaminated and reference rivers

    SciTech Connect

    Gagnon, M.M.; Bussieres, D.; Dodson, J.J. ); Hodson, P.V. )

    1995-02-01

    Induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity and accumulation of chlorophenolic compounds typical of bleached-kraft mill effluent (BKME) in fish sampled downstream of a pulp mill on the St. Maurice River, Quebec, Canada, provided evidence of chemical exposure to BKME. In comparison, fish sampled over the same distances and in similar habitats in a noncontaminated reference river, the Gatineau River, demonstrated low EROD activity and contamination levels. Accelerated growth of white suckers occurred between 2 and 10 years of age in both rivers at downstream stations relative to upstream stations, suggesting the existence of gradients of nutrient enrichment independent of BKME contamination. The impact of BKME exposure was expressed as reduced investment in reproduction, as revealed by greater length at maturity, reduced gonad size, and more variable fecundity. These effects were not obvious in simple upstream-downstream comparisons, but became evident when fish from the uncontaminated Gatineau River showed increased gonadal development and reduced age and size at maturity in response to enhanced growth rates.

  2. From sucker to saint: moralization in response to self-threat.

    PubMed

    Jordan, Alexander H; Monin, Benoît

    2008-08-01

    When people's rationality and agency are implicitly called into question by the more expedient behavior of others, they sometimes respond by feeling morally superior; this is referred to as the sucker-to-saint effect. In Experiment 1, participants who completed a tedious task and then saw a confederate quit the same task elevated their own morality over that of the confederate, whereas participants who simply completed the task or simply saw the confederate quit did not. In Experiment 2, this effect was eliminated by having participants contemplate a valued personal quality before encountering the rebellious confederate, a result suggesting a role for self-threat in producing moralization. These studies demonstrate that moral judgments can be more deeply embedded in judges' immediate social contexts-and driven more by motivations to maintain self-image-than is typically appreciated in contemporary moral-psychology research. Rather than uphold abstract principles of justice, moral judgment may sometimes just help people feel a little less foolish. PMID:18816289

  3. 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.

  4. 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)

  5. 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.

  6. Ambitwistor strings in four dimensions.

    PubMed

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

    2014-08-22

    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. PMID:25192087

  7. 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.

  8. Cooperative strings and glassy interfaces.

    PubMed

    Salez, Thomas; Salez, Justin; Dalnoki-Veress, Kari; Raphal, 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 ? of bulk relaxation. Finally, we explore the influence of sample boundaries when the system size becomes comparable to ?. 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

  9. Cooperative strings and glassy interfaces

    PubMed Central

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

    2015-01-01

    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 AdamGibbs description of glassy dynamics. Then, by including thermal dilatation, the VogelFulcherTammann 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 ? of bulk relaxation. Finally, we explore the influence of sample boundaries when the system size becomes comparable to ?. 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

  10. String solutions of Hofstadter problem

    NASA Astrophysics Data System (ADS)

    Abanov, A. G.; Talstra, J. C.; Wiegmann, P. B.

    1997-03-01

    We study the Bethe Ansatz equations for the Hofstadter problem discovered by Wiegmann and Zabrodin. We formulate an approximate solution to these equations which is analogous to the string solution of the exactly solvable 1D XXZ chain. We found a string solution for all energy levels for irrational flux. The key to the solution is that eigenfunction for one particular value of the flux can be written in terms of solutions at another (simpler) value of the flux, giving rise to a hierarchy picture of states, and making contact with conventional ways to classify fractal spectra. This string solution is the first occasion where tools from exactly solvable models are being applied to obtain analytical results in a model exhibiting multifractal properties. Finally, we compare our analytical results with numerical computer analysis.

  11. Status of rod consolidation, 1988

    SciTech Connect

    Bailey, W.J.

    1989-01-01

    It is estimated that the spent fuel storage pools at some domestic light-water reactors will run out of space before 2003, the year that the US Department of Energy currently predicts it will have a repository available. Of the methods being studied to alleviate the problem, rod consolidation is one of the leading candidates for achieving more efficient use of existing space in spent fuel storage pools. Rod consolidation involves mechanically removing all the fuel rods from the fuel assembly hardware (i.e., the structural components) and placing the fuel rods in a close-packed array in a canister without space grids. A typical goal of rod consolidation systems is to insert the fuel rods from two fuel assemblies into a canister that has the same exterior dimensions as one standard fuel assembly (i.e., to achieve a consolidation or compaction ratio of 2:1) and to compact the nonfuel-bearing structural components from those two fuel assemblies by a factor of 10 to 20. This report provides an overview of the current status of rod consolidation in the United States and a small amount of information on related activities in other countries. 85 refs., 36 figs., 5 tabs.

  12. Population Dynamics of Adult Lost River (Deltistes luxatus) and Shortnose (Chasmistes brevirostris) Suckers in Clear Lake Reservoir, California, 2006-08

    USGS Publications Warehouse

    Barry, Patrick M.; Janney, Eric C.; Hewitt, David A.; Hayes, Brian S.; Scott, Alta C.

    2009-01-01

    We report results from ongoing research into the population dynamics of endangered Lost River and shortnose suckers in Clear Lake Reservoir, California. Results are included for sampling that occurred from fall 2006 to spring 2008. We summarize catches and passive integrated transponder tagging efforts from trammel net sampling in fall 2006 and fall 2007, and report on detections of tagged suckers on remote antennas in the primary spawning tributary, Willow Creek, in spring 2007 and spring 2008. Results from trammel net sampling were similar to previous years, although catches of suckers in fall 2006 were lower than in 2007 and past years. Lost River and shortnose suckers combined made up about 80 percent of the sucker catch in each year, and more than 2,000 new fish were tagged across the 2 years. Only a small number of the suckers captured in fall sampling were recaptures of previously tagged fish, reinforcing the importance of remote detections of fish for capture-recapture analysis. Detections of tagged suckers in Willow Creek were low in spring 2007, presumably because of low flows. Nonetheless, the proportions of tagged fish that were detected were reasonably high and capture-recapture analyses should be possible after another year of data collection. Run timing for Lost River and shortnose suckers was well described by first detections of individuals by antennas in Willow Creek, although we may not have installed the antennas early enough in 2008 to monitor the earliest portion of the Lost River sucker migration. The duration and magnitude of the spawning runs for both species were influenced by flows and water temperature. Flows in Willow Creek were much higher in 2008 than in 2007, and far more detections were recorded in 2008 and the migrations were more protracted. In both years and for both species, migrations began in early March at water temperatures between 5 and 6 deg C and peaks were related to periods of increasing water temperature. The sex ratio of Lost River suckers detected in Willow Creek was skewed toward males, despite consistently more females having been tagged in fall sampling. This pattern indicates that some tagged female Lost River suckers may be spawning elsewhere in the system, and we intend to investigate this possibility to verify or alter the representativeness of our spring monitoring. Length frequency analysis of fall trammel net catches showed that the populations of both species in Clear Lake Reservoir have undergone major demographic transitions during the last 15 years. In the mid-1990s, the populations were dominated by larger fish and showed little evidence of recent recruitment. These larger fish apparently disappeared in the late 1990s and early 2000s, and the populations are now dominated by fish that recruited into the adult populations in the late 1990s. The length frequencies from the last 4 years provide evidence of consistent recruitment into the Lost River sucker population, but provide no such evidence for the shortnose sucker population. Overall, annual growth rates for both species in Clear Lake were 2-4 times greater than growth rates for conspecifics in Upper Klamath Lake. However, little or no growth occurred for either species in Clear Lake between 2006 and 2007. Based on available evidence, we are unable to fully explain differences in growth rates between systems or among years within Clear Lake.

  13. String Interactions in c=1 Matrix Model

    NASA Astrophysics Data System (ADS)

    de Boer, Jan; Sinkovics, Annamaria; Verlinde, Erik; Yee, Jung-Tay

    2004-03-01

    We study string interactions in the fermionic formulation of the c = 1 matrix model. We give a precise nonperturbative description of the rolling tachyon state in the matrix model, and discuss S-matrix elements of the c = 1 string. As a first step to study string interactions, we compute the interaction of two decaying D0-branes in terms of free fermions. This computation is compared with the string theory cylinder diagram using the rolling tachyon ZZ boundary states.

  14. 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.

  15. Constraints on string resonance amplitudes

    SciTech Connect

    Cheung, K.; Liu, Y.-F.

    2005-07-01

    We perform a global analysis of the tree-level open-string amplitudes in the limit s<string scale M{sub S}{>=}0.69-1.96 TeV at 95% confidence level for the Chan-Paton factors vertical bar T vertical bar=0-4. We also estimate the expected sensitivities at the CERN LHC, which can be as high as 19 TeV for vertical bar T vertical bar=4.

  16. Resurgent supersymmetry and string theory

    NASA Astrophysics Data System (ADS)

    Brust, Christopher

    2015-08-01

    We study a realization of accidental supersymmetry in type IIB string theory as a proof-of-principle of the mechanism and as a prototype of the strong sector present in resurgent supersymmetry, a warped UV-completion of natural supersymmetry. We first introduce the mechanism of accidental supersymmetry as a way of producing a supersymmetric spectrum in the IR of a quasi-conformal field theory, and then go on to discuss the utility of the mechanism in the specific BSM model of resurgent supersymmetry. The realization of accidental SUSY that we study is IIB string theory on an orbifold of the Klebanov-Strassler solution.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. Non-Abelian Strings and Axions

    SciTech Connect

    Shifman, M.

    2010-08-30

    Axion-like fields can have a strong impact on non-Abelian strings. I discuss axion connection to such strings and its implications in two cases: (i) axion localized on the strings, and (ii) axions propagating in the four-dimensional bulk.

  2. 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…

  3. Hopf solitons and elastic rods

    SciTech Connect

    Harland, Derek; Sutcliffe, Paul; Speight, Martin

    2011-03-15

    Hopf solitons in the Skyrme-Faddeev model are stringlike topological solitons classified by the integer-valued Hopf charge. In this paper we introduce an approximate description of Hopf solitons in terms of elastic rods. The general form of the elastic rod energy is derived from the field theory energy and is found to be an extension of the classical Kirchhoff rod energy. Using a minimal extension of the Kirchhoff energy, it is shown that a simple elastic rod model can reproduce many of the qualitative features of Hopf solitons in the Skyrme-Faddeev model. Features that are captured by the model include the buckling of the charge three solution, the formation of links at charges five and six, and the minimal energy trefoil knot at charge seven.

  4. 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. PMID:11497820

  5. String Universality in Ten Dimensions

    SciTech Connect

    Adams, Allan; Taylor, Washington; DeWolfe, Oliver

    2010-08-13

    We show that the N=1 supergravity theories in ten dimensions with gauge groups U(1){sup 496} and E{sub 8}xU(1){sup 248} are not consistent quantum theories. Cancellation of anomalies cannot be made compatible with supersymmetry and Abelian gauge invariance. Thus, in ten dimensions all supersymmetric theories of gravity without known inconsistencies are realized in string theory.

  6. String formation beyond leading colour

    NASA Astrophysics Data System (ADS)

    Christiansen, Jesper R.; Skands, Peter Z.

    2015-08-01

    We present a new model for the hadronisation of multi-parton systems, in which colour correlations beyond leading N C are allowed to influence the formation of confining potentials (strings). The multiplet structure of SU(3) is combined with a minimisation of the string potential energy, to decide between which partons strings should form, allowing also for "baryonic" configurations (e.g., two colours can combine coherently to form an anticolour). In e + e -collisions, modifications to the leading-colour picture are small, suppressed by both colour and kinematics factors. But in pp collisions, multi-parton interactions increase the number of possible subleading connections, counteracting their naive 1/ N {/C 2} suppression. Moreover, those that reduce the overall string lengths are kinematically favoured. The model, which we have implemented in the PYTHIA 8 generator, is capable of reaching agreement not only with the important < p ?> ( n charged) distribution but also with measured rates (and ratios) of kaons and hyperons, in both ee and pp collisions. Nonetheless, the shape of their p ? spectra remains challenging to explain.

  7. Evolution of cosmic string configurations

    NASA Astrophysics Data System (ADS)

    Austin, Daren; Copeland, E. J.; Kibble, T. W. B.

    1993-12-01

    We extend and develop our previous work on the evolution of a network of cosmic strings. The new treatment is based on an analysis of the probability distribution of the end-to-end distance, or extension, of a randomly chosen segment of left-moving string of given length. The description involves three distinct length scales: ?, related to the overall string density, ?, the persistance length along the string, and ?, describing the small-scale structure, which is an important feature of the numerical simulations that have been done of this problem. An evolution equation is derived describing how the distribution develops in time due to the combined effects of the universal expansion, of intercommuting and loop formation, and of gravitational radiation. With plausible assumptions about the unknown parameters in the model, we confirm the conclusions of our previous study that if gravitational radiation and small-scale structure effects are neglected the two dominant length scales both scale in proportion to the horizon size. When the extra effects are included, we find that while ? and ? grow, ? initially does not. Eventually, however, it does appear to scale, at a much lower level, due to the effects of gravitational back reaction.

  8. String universality in ten dimensions.

    PubMed

    Adams, Allan; Taylor, Washington; Dewolfe, Oliver

    2010-08-13

    We show that the N=1 supergravity theories in ten dimensions with gauge groups U(1){496} and E{8}×U(1){248} are not consistent quantum theories. Cancellation of anomalies cannot be made compatible with supersymmetry and Abelian gauge invariance. Thus, in ten dimensions all supersymmetric theories of gravity without known inconsistencies are realized in string theory. PMID:20868028

  9. New Approaches to String Instruction.

    ERIC Educational Resources Information Center

    Teaching Music, 1994

    1994-01-01

    Maintains that use of the Suzuki, Orff, and Dalcroze methods have assisted string teachers in helping music students achieve mastery from the beginning of instruction. Describes how these methods are used by five music teachers. Includes addresses of organizations that provide information about these music teaching methods. CFR)

  10. Magnetogenesis from cosmic string loops

    SciTech Connect

    Battefeld, Diana; Battefeld, Thorsten; Wesley, Daniel H; Wyman, Mark E-mail: tbattefe@princeton.edu E-mail: mwyman@perimeterinstitute.ca

    2008-02-15

    Large scale coherent magnetic fields are observed in galaxies and clusters, but their ultimate origin remains a mystery. We reconsider the prospects for primordial magnetogenesis by a cosmic string network. We show that the magnetic flux produced by long strings has been overestimated in the past, and give improved estimates. We also compute the fields created by the loop population, and find that it gives the dominant contribution to the total magnetic field strength on present-day galactic scales. We present numerical results obtained by evolving semi-analytic models of string networks (including both one-scale and velocity-dependent one-scale models) in a {Lambda}CDM cosmology, including the forces and torques on loops from Hubble redshifting, dynamical friction, and gravitational wave emission. Our predictions include the magnetic field strength as a function of the correlation length, as well as the volume covered by magnetic fields. We conclude that string networks could account for magnetic fields on galactic scales, but only if coupled with an efficient dynamo amplification mechanism.

  11. String theory in target space

    NASA Astrophysics Data System (ADS)

    Boels, Rutger H.; Hansen, Tobias

    2014-06-01

    It is argued that the complete S-matrix of string theory at tree level in a flat background can be obtained from a small set of target space properties, without recourse to the worldsheet description. The main non-standard inputs are (generalised) Britto-Cachazo-Feng-Witten shifts, as well as the monodromy relations for open string theory and the Kawai-Lewellen-Tye relations for closed string theory. The roots of the scattering amplitudes and especially their appearance in the residues at the kinematic poles are central to the story. These residues determine the amplitudes through on-shell recursion relations. Several checks of the formalism are presented, including a computation of the Koba-Nielsen amplitude in the bosonic string. Furthermore the question of target space unitarity is (re-)investigated. For the Veneziano amplitude this question is reduced by Poincar invariance, unitarity and locality to that of positivity of a particular numerical sum. Interestingly, this analysis produces the main conditions of the no-ghost theorem on dimension and intercept from the first three poles of this amplitude.

  12. Metastable Quivers in String Compactifications

    SciTech Connect

    Diaconescu, Duiliu-Emanuel; Donagi, Ron; Florea, Bogdan; /SLAC

    2007-01-08

    We propose a scenario for dynamical supersymmetry breaking in string compactifications based on geometric engineering of quiver gauge theories. In particular we show that the runaway behavior of fractional branes at del Pezzo singularities can be stabilized by a flux superpotential in compact models. Our construction relies on homological mirror symmetry for orientifolds.

  13. Distribution and condition of young-of-year Lost River and shortnose suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon, 2008-10--Final Report

    USGS Publications Warehouse

    Burdick, Summer M.; Hewitt, David A.

    2012-01-01

    We were unable to compare health and condition of juvenile suckers among habitats, due to their movement among habitats. However, documentation of length-weight relationships, afflictions and deformities, and histology indicated juvenile suckers captured in all habitats maintained a similar level of health among the 3 years of our study.

  14. 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.

  15. Gravitational lensing by straight cosmic strings

    NASA Astrophysics Data System (ADS)

    Kotvytskiy, A. T.

    2015-07-01

    We consider effects due to gravitational lensing by hypothetical cosmic strings. We briefly review facts concerning infinite straight strings, obtain the equation for a gravitational lens produced by an infinite string in the classical form, and analyze features of the gravitational lensing for a given object in detail. We consider a finite straight string. We present caustics and critical curves for strings with different lengths and also some images produced by the considered gravitational lens. We propose a method for constructing brightness curves numerically. As an example of the working capacity of this method, we construct a concrete brightness curve for certain gravitational lens parameters.

  16. 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.

  17. Reduced growth and survival of larval razorback sucker fed selenium-laden zooplankton

    USGS Publications Warehouse

    Hamilton, S.J.; Buhl, K.J.; Bullard, F.A.; McDonald, S.F.

    2005-01-01

    Four groups of larval razorback sucker, an endangered fish, were exposed to selenium-laden zooplankton and survival, growth, and whole-body residues were measured. Studies were conducted with 5, 10, 24, and 28-day-old larvae fed zooplankton collected from six sites adjacent to the Green River, Utah. Water where zooplankton were collected had selenium concentrations ranging from <0.4 to 78 ??g/L, and concentrations in zooplankton ranged from 2.3 to 91 ??g/g dry weight. Static renewal tests were conducted for 20 to 25 days using reference water with selenium concentrations of <1.1 ??g/L. In all studies, 80-100% mortality occurred in 15-20 days. In the 28-day-old larvae, fish weight was significantly reduced 25% in larvae fed zooplankton containing 12 ??g/g selenium. Whole-body concentrations of selenium ranged from 3.7 to 14.3 ??g/g in fish fed zooplankton from the reference site (Sheppard Bottom pond 1) up to 94 ??g/g in fish fed zooplankton from North Roadside Pond. Limited information prior to the studies suggested that the Sheppard pond 1 site was relatively clean and suitable as a reference treatment; however, the nearly complete mortality of larvae and elevated concentrations of selenium in larvae and selenium and other elements in zooplankton indicated that this site was contaminated with selenium and other elements. Selenium concentrations in whole-body larvae and in zooplankton from all sites were close to or greater than toxic thresholds where adverse effects occur in fish. Delayed mortality occurred in larvae fed the two highest selenium concentrations in zooplankton and was thought due to an interaction with other elements. ?? 2004 Elsevier Inc. All rights reserved.

  18. Impact of selenium and other trace elements on the endangered adult razorback sucker.

    PubMed

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

    2002-01-01

    A study was conducted with endangered the razorback sucker (Xyrauchen texanus) to determine if environmental exposure to selenium in flooded bottomland sites affected survival, growth, and egg-hatching success. Adults were stocked at three sites adjacent to the Colorado River near Grand Junction, Colorado, in July 1996: hatchery ponds at Horsethief Canyon State Wildlife Area (referred to here as Horsethief; the reference site), a diked tertiary channel at Adobe Creek, and North Pond at Walter Walker State Wildlife Area (WWSWA). Fish were collected in April 1997 and spawned. After two spawnings adults from the three sites were held at Horsethief for an 86-day selenium depuration period. Selenium concentrations at Horsethief were 1.4-3.0 microg/L in water, 0.8-0.9 microg/g in sediment, 4.5 microg/g in muscle plug, and 6.0 microg/g in eggs; at Adobe Creek, <0.7-4.5 microg/L in water, 1.2-2.5 microg/g in sediment, 16-20 microg/g in zooplankton, 9.6 microg/g in muscle plug, and 40 microg/g in eggs; and at North Pond, 3.2-17 microg/L in water, 16-94 microg/g in sediment, 32-48 microg/g in zooplankton, 14 microg/g in muscle plug, and 55 microg/g in eggs. During the depuration period, when adults from Adobe Creek and North Pond were held at Horsethief, the fish lost 7%-13% of their selenium burden in 59 days and 14%-21% in 86 days. Larvae from North Pond adults had the most deformities, followed by Adobe Creek adults, with the fewest deformities found in the Horsethief adults. PMID:12203951

  19. Effects of total dissolved gas supersaturated water on lethality and catalase activity of Chinese sucker (Myxocyprinus asiaticus Bleeker)*

    PubMed Central

    Chen, Shi-chao; Liu, Xiao-qing; Jiang, Wen; Li, Ke-feng; Du, Jun; Shen, Dan-zhou; Gong, Quan

    2012-01-01

    Total dissolved gas (TDG) supersaturation caused by dam sluicing can result in gas bubble trauma (GBT) in fish and threaten their survival. In the present study, Chinese suckers (Myxocyprinus asiaticus Bleeker) were exposed to TDG supersaturated water at levels ranging from 120% to 145% for 48 h. The median lethal concentration (LC50) and the median lethal time (LT50) were determined to evaluate acute lethal effects on Chinese suckers. The results showed that the LC50 values of 4, 6, 8, and 10 h were 142%, 137%, 135%, and 130%, respectively. The LT50 values were 3.2, 4.7, 7.8, 9.2, and 43.4 h, respectively, when TDG supersaturated levels were 145%, 140%, 135%, 130%, and 125%. Furthermore, the biological responses in Chinese suckers were studied by assaying the catalase (CAT) activities in gills and muscles at the supersaturation level of 140% within LT50. The CAT activities in the gills and muscle tissues exhibited a regularity of a decrease after an increase. CAT activities in the muscles were increased significantly at 3/5LT50 (P<0.05) and then came back to the normal level. However, there were no significant differences between the treatment group (TDG level of 140%) and the control group (TDG level of 100%) on CAT activities in the gills before 3/5LT50 (P>0.05), but the activities were significantly lower than the normal level at 4/5LT50 and LT50 (P<0.05). PMID:23024046

  20. Effects of total dissolved gas supersaturated water on lethality and catalase activity of Chinese sucker (Myxocyprinus asiaticus Bleeker).

    PubMed

    Chen, Shi-chao; Liu, Xiao-qing; Jiang, Wen; Li, Ke-feng; Du, Jun; Shen, Dan-zhou; Gong, Quan

    2012-10-01

    Total dissolved gas (TDG) supersaturation caused by dam sluicing can result in gas bubble trauma (GBT) in fish and threaten their survival. In the present study, Chinese suckers (Myxocyprinus asiaticus Bleeker) were exposed to TDG supersaturated water at levels ranging from 120% to 145% for 48 h. The median lethal concentration (LC(50)) and the median lethal time (LT(50)) were determined to evaluate acute lethal effects on Chinese suckers. The results showed that the LC(50) values of 4, 6, 8, and 10 h were 142%, 137%, 135%, and 130%, respectively. The LT(50) values were 3.2, 4.7, 7.8, 9.2, and 43.4 h, respectively, when TDG supersaturated levels were 145%, 140%, 135%, 130%, and 125%. Furthermore, the biological responses in Chinese suckers were studied by assaying the catalase (CAT) activities in gills and muscles at the supersaturation level of 140% within LT(50). The CAT activities in the gills and muscle tissues exhibited a regularity of a decrease after an increase. CAT activities in the muscles were increased significantly at 3/5LT(50) (P<0.05) and then came back to the normal level. However, there were no significant differences between the treatment group (TDG level of 140%) and the control group (TDG level of 100%) on CAT activities in the gills before 3/5LT(50) (P>0.05), but the activities were significantly lower than the normal level at 4/5LT(50) and LT(50) (P<0.05). PMID:23024046

  1. Efficacy of hydrogen peroxide in controlling mortality associated with saprolegniasis on walleye, white sucker, and paddlefish eggs

    USGS Publications Warehouse

    Gaikowski, M.P.; Rach, J.J.; Drobish, M.; Hamilton, J.; Harder, T.; Lee, L.A.; Moen, C.; Moore, A.

    2003-01-01

    The efficacy of hydrogen peroxide in controlling saprolegniasis on eggs of walleye Stizostedion vitreum, white sucker Catostomus commersoni, and paddlefish Polyodon spathula was evaluated at four private, state, and federal production hatcheries participating in an Investigational New Animal Drug efficacy study (experiment 1; walleyes) and in a laboratory-based miniature egg jar incubation system (experiment 2; walleyes, white suckers, and paddlefish). Naturally occurring fungal infestations (saprolegniasis) were observed on eggs in both experiments. Confirmatory diagnosis of infested eggs from one hatchery in experiment 1 identified the pathogen as Saprolegnia parasitica. During experiment 1, eggs were treated daily for 15 min with either 0, 500, or 750 mg/L of hydrogen peroxide, and one trial compared a 500-mg/L hydrogen peroxide treatment with a formalin treatment at 1,667 mg/L. Saprolegniasis infestation was observed in control egg jars, whereas treatment with either formalin or hydrogen peroxide virtually eliminated the infestation. Hydrogen peroxide treatments of 500 mg/L either increased egg hatch or were as effective as physical removal of infested eggs in controlling mortality. Although treatment with formalin at 1,667 mg/L significantly increased the percent eye-up of walleye eggs compared with that of those treated with hydrogen peroxide at 500 mg/L, the difference was only 1.9-2.6%. In experiment 2, noneyed eggs were treated for 15 min every other day with 0, 283, 565, or 1,130 mg/L of hydrogen peroxide until the viable eggs hatched. Saprolegniasis infestation engulfed most control eggs, whereas infestation of treated eggs was either reduced or not visible. Hydrogen peroxide significantly increased egg hatch for all three species tested in experiment 2. Although hydrogen peroxide treatments as low as 283 mg/L significantly increased walleye and white sucker hatch, treatments between 500 and 1,000 mg/L are more likely to be effective in production egg incubation systems.

  2. 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)

  3. 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.

  4. 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.

  5. How Superconducting Cosmic Strings Can Be Found

    NASA Astrophysics Data System (ADS)

    Grats, Yuri

    1995-08-01

    It is known that strings in certain models can exhibit superconductivity and carry a very large electric current. Superconducting strings have received a lot of attention in the cosmological context, and some observational consequences of the fact that superconducting strings might be formed in the Universe have been discussed. We'll show that a collision of two stright cosmic strings one of which is a superconducting one may be accompanied by the emission of a Cherenkov -like electromagnetic radiation. Whithin the context of string cosmological scenarios, this new mechanism should be taken into account in calculations of the energy of the early stages of evolution of the string network, as fairly effective energy-loss mechanism, which has not previously been discussed in literature. On the other hand, the characteristsic features of the spectrum and angular distribution of the radiation can be utilized in searches for observable manifestations of superconducting strings.

  6. Status and trends of adult Lost River (Deltistes luxatus) and shortnose (Chasmistes brevirostris) sucker populations in Upper Klamath Lake, Oregon, 2014

    USGS Publications Warehouse

    Hewitt, David A.; Janney, Eric C.; Hayes, Brian S.; Harris, Alta C.

    2015-01-01

    Despite relatively high survival in most years, we conclude that both species have experienced substantial decreases in the abundance of spawning adults because losses from mortality have not been balanced by recruitment of new individuals. Although capture-recapture data indicate substantial recruitment of new individuals into the spawning populations for SNS and river spawning LRS in some years, size data do not corroborate these estimates. As a result, the status of the endangered sucker populations in Upper Klamath Lake remains worrisome, especially for shortnose suckers. Our monitoring program provides a robust platform for estimating vital population parameters, evaluating the status of the populations, and assessing the effectiveness of conservation and recovery efforts.

  7. Distribution, Health, and Development of Larval and Juvenile Lost River and Shortnose Suckers in the Williamson River Delta Restoration Project and Upper Klamath Lake, Oregon: 2008 Annual Data Summary

    USGS Publications Warehouse

    Burdick, Summer M.; Ottinger, Christopher; Brown, Daniel T.; VanderKooi, Scott P.; Robertson, Laura; Iwanowicz, Deborah

    2009-01-01

    Federally endangered Lost River sucker Deltistes luxatus and shortnose sucker Chasmistes brevirostris were once abundant throughout their range but populations have declined; they have been extirpated from several lakes, and may no longer reproduce in others. Poor recruitment into 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 rearing habitat. Within Upper Klamath Lake, a lack of marshes also may allow larval suckers to be swept from suitable rearing areas downstream into the seasonally anoxic waters of the Keno Reservoir. The Nature Conservancy (TNC) flooded about 3,600 acres to the north of the Williamson River mouth (Tulana Unit) in October 2007, and about 1,400 acres 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 for suckers, and improve water quality. In collaboration with TNC, the Bureau of Reclamation, and Oregon State University, we began a long-term collaborative research and monitoring program in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. Our approach includes two equally important aspects. One component is to describe habitat use and colonization processes by larval and juvenile suckers and non-sucker fish species. The second is to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report contains a summary of the first year of data collected as a part of this monitoring effort.

  8. 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.

  9. Influence of Rod Contouring on Rod Strength and Stiffness in Spine Surgery.

    PubMed

    Demura, Satoru; Murakami, Hideki; Hayashi, Hiroyuki; Kato, Satoshi; Yoshioka, Katsuhito; Yokogawa, Noriaki; Ishii, Takayoshi; Igarashi, Takashi; Fang, Xiang; Tsuchiya, Hiroyuki

    2015-06-01

    For spinal fusion or the correction of spine deformity at multiple levels, intraoperative rod contouring is required to realign the spine. A French bender is the most common contouring tool used. There are several reports on the mechanical properties of various rods with manufactured straight rod; however, few reports describe the changes in a rod's mechanical properties after rod contouring. The authors investigated the influences of rod contouring on rod strength and stiffness. A 3-point bending test was conducted. Each 18-cm rod was loaded at a rate of 10 mm/min with a load applicator. Three different rod diameters (5.5, 6.0, and 6.35 mm) and 2 types of materials (titanium [Ti] alloy and cobalt-chromium [CoCr] alloy) were assessed. Different rod curvatures were evaluated: (1) a no-preparation rod of 0 (control); (2) a 0 rod bent at one point to make tangential angles of 10 and then bent back from the opposite side; (3) a bent rod with tangential angles of 20; and (4) a 40 bent rod. The yield strength in all types of rod materials and diameter decreased after rod contouring using a French bender. The extent of decrease depended on the degree of bend. The bending stiffness of each rod also decreased. The CoCr rod showed higher bending stiffness than the Ti rod of the same diameter. Rod contouring using a French bender reduced the yield strength and stiffness in all types of rods. Decrease of yield strength correlated to the degree of bend. In the comparison of 20 and 40 contoured rods, the 6.0-mm CoCr rod showed the highest reduction force. This study found that rod contouring procedures reduced rod yield strength and stiffness. PMID:26091226

  10. String homology and Lie algebra structures

    NASA Astrophysics Data System (ADS)

    Tabing, Felicia Y.

    Chas and Sullivan introduced string homology, which is the equivariant homology of the loop space with the circle action on loops by rotation. Craig Westerland computed the string homology for spheres with coeffcients in Z 2 and in Somnath Basu's dissertation, he computes the string homology and string bracket for spheres over rational coefficients, and he finds that the bracket is trivial. In this paper, we compute string homology and the string bracket for spheres with integer coefficients, treating the odd- and even-dimensional cases separately. We use the Gysin sequence and Leray-Serre spectral sequence to aid in our computations. We find that over the integers, the string Lie algebra bracket structure is more interesting, and not always zero as in Basu's thesis. The string bracket turns out to be non-zero on torsion coming from string homology. We also make some computations of the Goldman Lie algebra structure, and more generally, the string Lie algebra structure of closed, orientable surfaces.

  11. Filter for a drill string

    SciTech Connect

    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.

  12. Vanishing theorems and string backgrounds

    NASA Astrophysics Data System (ADS)

    Ivanov, S.; Papadopoulos, G.

    2001-03-01

    We show various vanishing theorems for the cohomology groups of compact Hermitian manifolds for which the Bismut connection has a (restricted) holonomy contained in SU(n) and classify all such manifolds of dimension four. In this way we provide necessary conditions for the existence of such structures on compact Hermitian manifolds with vanishing first Chern class of non-Khler type. Then we apply our results to solutions of the string equations and show that such solutions admit various cohomological restrictions such as, for example, that under certain natural assumptions the plurigenera vanish. We also find that under some assumptions the string equations are equivalent to the condition that a certain vector is parallel with respect to the Bismut connection.

  13. Orbifolds of M-strings

    NASA Astrophysics Data System (ADS)

    Haghighat, Babak; Kozaz, 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.

  14. Comparative studies of bile salts. 5?-Chimaerol, a new bile alcohol from the white sucker Catostomus commersoni Lacpde

    PubMed Central

    Anderson, I. G.; Haslewood, G. A. D.

    1970-01-01

    1. G.l.c. examination of bile alcohols prepared from the sucker Catostomus commersoni Lacpde (family Catostomidae) showed that although 5?-cyprinol (5?-cholestane-3?,7?,12?,26,27-pentol) was a minor constituent, the principal bile alcohol was an undescribed substance, probably present in the bile as the C-26 sulphate ester, whose i.r., n.m.r. and mass spectra agreed with the structure 5?-cholestane-3?,7?,12?,24,26-pentol. 2. MD studies suggest that this 5?-chimaerol is the 24(+), 25S enantiomer and that 5?-chimaerol (chimaerol) from Chimaera monstrosa bile also has the 24(+), 25S configuration. These findings imply that bile alcohol biosynthesis in suckers and chimaeras includes stereospecific oxidation of cholesterol at C-26. 3. C. commersoni bile acids (present in minor amounts) probably consist largely of 3?,7?,12?-trihydroxy-5?-cholan-24-oic acid (allocholic acid). 4. 5?-Chimaerol sulphate and 5?-cyprinol sulphate are probably biochemically equivalent as bile salts, and can be considered as arising by parallel evolution. PMID:5435487

  15. Apparatus and method for vibrating a casing string during cementing

    SciTech Connect

    Rankin, R.E.; Rankin, K.T.

    1992-10-06

    This patent describes a method of cementing a string of casing in a well. It comprises: securing a vibrating device into the string of casing near the lower end of the string of casing; lowering the string of casing into the well to the desired depth; pumping a cement slurry down the string of casing; causing a portion of the cement slurry being pumped down the string of casing to vibrate the vibrating device; and wherein the vibrating device is secured in the string of casing by cementing the vibrating device within a sub, then securing the sub into the string of casing prior to lowering the string of casing into the well.

  16. 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.

  17. String and supergravity motivated cosmology

    NASA Astrophysics Data System (ADS)

    Kallosh, R.

    2005-07-01

    In this pedagogical lecture we explain some basic part of the standard cosmological model which is most relevant for the fundamental theoretical physics. We stress the common features and differences between early universe inflation and late-time acceleration. We than proceed with some recent attempts to address the issues of cosmology in string theory and higher dimensional supergravity with the emphasis on successes and still unsolved problems.

  18. String networks as tropical curves

    NASA Astrophysics Data System (ADS)

    Ray, Koushik

    2008-09-01

    A prescription for obtaining supergravity solutions for planar (p,q)-string networks is presented, based on earlier results. It shows that networks may be looked upon as tropical curves emerging as the spine of the amoeba of a holomorphic curve in M-theory. The Khler potential of supergravity is identified with the corresponding Ronkin function. Implications of this identification in counting dyons is discussed.

  19. 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

  20. Resumming the string perturbation series

    NASA Astrophysics Data System (ADS)

    Grassi, Alba; Mario, Marcos; Zakany, Szabolcs

    2015-05-01

    We use the AdS/CFT correspondence to study the resummation of a perturbative genus expansion appearing in the type II superstring dual of ABJM theory. Although the series is Borel summable, its Borel resummation does not agree with the exact non-perturbative answer due to the presence of complex instantons. The same type of behavior appears in the WKB quantization of the quartic oscillator in Quantum Mechanics, which we analyze in detail as a toy model for the string perturbation series. We conclude that, in these examples, Borel summability is not enough for extracting non-perturbative information, due to non-perturbative effects associated to complex instantons. We also analyze the resummation of the genus expansion for topological string theory on local , which is closely related to ABJM theory. In this case, the non-perturbative answer involves membrane instantons computed by the refined topological string, which are crucial to produce a well-defined result. We give evidence that the Borel resummation of the perturbative series requires such a non-perturbative sector.

  1. Cosmological consequences of string axions

    SciTech Connect

    Kain, Ben

    2006-06-15

    Axion fluctuations generated during inflation lead to isocurvature and non-Gaussian temperature fluctuations in the cosmic microwave background radiation. Following a previous analysis for the model independent string axion we consider the consequences of a measurement of these fluctuations for two additional string axions. We do so independent of any cosmological assumptions. The first axion has been shown to solve the strong CP problem for most compactifications of the heterotic string while the second axion, which does not solve the strong CP problem, obeys a mass formula which is independent of the axion scale. We find that if gravitational waves interpreted as arising from inflation are observed by the PLANCK polarimetry experiment with a Hubble constant during inflation of H{sub inf} > or approx. 10{sup 13} GeV the existence of the first axion is ruled out and the second axion cannot obey the scale independent mass formula. In an appendix we quantitatively justify the often held assumption that temperature corrections to the zero temperature QCD axion mass may be ignored for temperatures T < or approx. {lambda}{sub QCD}.

  2. Cosmological Consequences of String Axions

    SciTech Connect

    Kain, Ben

    2005-12-15

    Axion fluctuations generated during inflation lead to isocurvature and non-Gaussian temperature fluctuations in the cosmic microwave background radiation. Following a previous analysis for the model independent string axion we consider the consequences of a measurement of these fluctuations for two additional string axions. We do so independent of any cosmological assumptions except for the axions being massless during inflation. The first axion has been shown to solve the strong CP problem for most compactifications of the heterotic string while the second axion, which does not solve the strong CP problem, obeys a mass formula which is independent of the axion scale. We find that if gravitational waves interpreted as arising from inflation are observed by the PLANCK polarimetry experiment with a Hubble constant during inflation of H{sub inf} {approx}> 10{sup 13} GeV the existence of the first axion is ruled out and the second axion cannot obey the scale independent mass formula. In an appendix we quantitatively justify the often held assumption that temperature corrections to the zero temperature QCD axion mass may be ignored for temperatures T {approx}< {Lambda}{sub QCD}.

  3. Stuck fuel rod capping sleeve

    DOEpatents

    Gorscak, Donald A. (Bethel Park, PA); Maringo, John J. (McKeesport, PA); Nilsen, Roy J. (Upper St. Clair, PA)

    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

  4. 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.

  5. 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.

  6. Relation between strings and ribbon knots

    SciTech Connect

    Ahmed, E. Mansoura Univ. ); El-Rifai, E.A. ); Abdellatif, R.A. )

    1991-02-01

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

  7. 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.

  8. 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.

  9. Pion string evolving in a thermal bath

    NASA Astrophysics Data System (ADS)

    Lu, Fan; Chen, Qichang; Mao, Hong

    2015-10-01

    By using the symmetry improved Cornwall-Jackiw-Tomboulis effective formalism, we study a pion string of the O (4 ) linear sigma model at finite temperature in chiral limit. In terms of the Kibble-Zurek mechanism we reconsider the production and evolution of the pion string in a thermal bath. Finally, we estimate the pion string density and its possible signal during the chiral phase transition.

  10. 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.

  11. 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.

  12. Tagging age-1 Lost River and shortnose suckers with passive integrated transponders, Upper Klamath Lake, Oregon–Summary of 2009–11 effort

    USGS Publications Warehouse

    Burdick, Summer M.

    2012-01-01

    A passive integrated transponder (PIT) tagging study was initiated in 2009 for age-1 endangered Lost River and shortnose suckers in Upper Klamath Lake, Oregon, for the purpose of examining causes of mortality, validating estimated age to maturity, and examining movement patterns. This study, which was done opportunistically in 2009 and 2010, received funding in 2011 for a directed tagging effort. Tags were redetected using an existing infrastructure of remote PIT tag readers and tag scanning surveys at American white pelican and double-crested cormorant breeding and loafing areas. Individual fish histories are used to describe the distance, direction, and timing of age-1 sucker movement. Sucker PIT tag detections in the Sprague and Williamson rivers in mid-summer and in autumn indicate age-1 suckers use these tributaries outside of the known spring spawning season. PIT tags detected in bird habitats indicate predation by birds may have been a cause of mortality in 2009. Field conditions prevented scanning bird breeding and loafing areas in Upper Klamath Wildlife National Refuge for tags in 2011, however, limiting our ability to make inferences about bird predation in those years.

  13. Health of white sucker within the St. Louis River area of concern associated with habitat usage as assessed using stable isotopes.

    PubMed

    Blazer, V S; Hoffman, J; Walsh, H L; Braham, R P; Hahn, C; Collins, P; Jorgenson, Z; Ledder, T

    2014-03-01

    In Spring 2011, 200 adult white sucker were collected in four areas of the St. Louis River area of concern (AOC), located in Minnesota and Wisconsin, USA. The areas included the upper AOC as a reference area, the upper estuary, St. Louis Bay and Superior Bay. Grossly visible abnormalities were documented and preserved for microscopic analyses, as were five to eight representative pieces of liver tissue. A piece of dorsal muscle was preserved for stable isotope analyses and otoliths removed for age determination. The incidence of raised skin lesions (mucoid plaques) was high (31%), however, microscopically only 4.5% of the white suckers had neoplasia (papillomas). The remaining lesions were epidermal hyperplasia. Superior Bay had the lowest percentage of skin/lip lesions (10%), while St. Louis Bay had the highest (44%). St. Louis Bay also had the highest incidence of skin neoplasms (12%). No hepatocellular neoplasms were documented, however bile duct tumors were observed in 4.5% of the suckers. Foci of cellular alteration were observed in fish from all sites except the upper AOC. Stable isotope data indicated that most of the suckers relied on the St. Louis River AOC for the majority (>75%) of their diet, indicating they were resident within the AOC and not in Lake Superior. The amount of diet obtained from the upper estuary was a significant predictor of skin lesion incidence. Hence, habitat use within the AOC appears to be an important risk factor for skin and possibly, liver lesions. PMID:24370817

  14. Health of white sucker within the St. Louis River area of concern associated with habitat usage as assessed using stable isotopes

    EPA Science Inventory

    In Spring 2011, 200 adult white sucker were collected in four areas of the St. Louis River Area of Concern (AOC), located in Minnesota and Wisconsin, USA. The areas included the upper AOC as a reference area, the upper estuary, St. Louis Bay and Superior Bay. Grossly visible abno...

  15. Health of white sucker within the St. Louis River area of concern associated with habitat usage as assessed using stable isotopes

    USGS Publications Warehouse

    Blazer, V.S.; Hoffman, J.; Walsh, H.L.; Braham, R.P.; Hahn, C.; Collins, P.; Jorgenson, Z.; Ledder, T.

    2014-01-01

    In Spring 2011, 200 adult white sucker were collected in four areas of the St. Louis River area of concern (AOC), located in Minnesota and Wisconsin, USA. The areas included the upper AOC as a reference area, the upper estuary, St. Louis Bay and Superior Bay. Grossly visible abnormalities were documented and preserved for microscopic analyses, as were five to eight representative pieces of liver tissue. A piece of dorsal muscle was preserved for stable isotope analyses and otoliths removed for age determination. The incidence of raised skin lesions (mucoid plaques) was high (31 %), however, microscopically only 4.5 % of the white suckers had neoplasia (papillomas). The remaining lesions were epidermal hyperplasia. Superior Bay had the lowest percentage of skin/lip lesions (10 %), while St. Louis Bay had the highest (44 %). St. Louis Bay also had the highest incidence of skin neoplasms (12 %). No hepatocellular neoplasms were documented, however bile duct tumors were observed in 4.5 % of the suckers. Foci of cellular alteration were observed in fish from all sites except the upper AOC. Stable isotope data indicated that most of the suckers relied on the St. Louis River AOC for the majority (>75 %) of their diet, indicating they were resident within the AOC and not in Lake Superior. The amount of diet obtained from the upper estuary was a significant predictor of skin lesion incidence. Hence, habitat use within the AOC appears to be an important risk factor for skin and possibly, liver lesions.

  16. Twistor Strings, Gauge Theory and Gravity

    SciTech Connect

    Abou-Zeid, Mohab

    2008-04-21

    The development of new analytic and computational methods in the perturbative approach to Yang-Mills theories is of great importance to the understanding of LHC physics. Twistor string theory, a form of string theory defined on Penrose's twistor space, may provide a very efficient and powerful alternative to the usual Feynman diagram expansion of field theory. I survey the recent construction of a family of new twistor string theories which are free from world-sheet anomalies and give the space-time spectra of Einstein supergravities, with second order field equations instead of the higher derivative conformal supergravities that arose from earlier twistor strings.

  17. 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.

  18. A new string in ten dimensions?

    NASA Astrophysics Data System (ADS)

    Sethi, Savdeep

    2013-09-01

    I suggest the possibility of a new string in ten dimensions. Evidence for this string is presented both from orientifold physics and from K-theory, along with a mystery concerning the M-theory description. Motivated by this possibility, some novel aspects of decoupling limits in heterotic/type I theories are described; specifically, the decoupled theory on type I D-strings is argued to be three-dimensional rather than two-dimensional. These decoupled theories provide the matrix model definitions of the heterotic/type I strings.

  19. 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.

  20. Stretched strings in tachyon condensation models

    NASA Astrophysics Data System (ADS)

    Minahan, Joseph A.

    2002-05-01

    In this note, we consider the two derivative truncation of boundary string field theory for the unstable D9-brane in type-IIA string theory. We construct multiples of the stable codimension 1 solitons that correspond to stacks of D8-branes. We find the fluctuation modes that correspond to open strings stretching between the branes, and find that their masses are consistent with the string tension. We show that these modes are localized halfway between the branes and that their width is independent of the brane separation.

  1. Gravitational scattering of photons off cosmic strings

    NASA Astrophysics Data System (ADS)

    Chu, Yi-Zen; Vachaspati, Tanmay

    2013-04-01

    Photons can gravitationally scatter off a cosmic string loop and gain or lose energy. We consider the spectral distortion induced by cosmic string loops placed in an ambient thermal bath of photons. The fractional deviation from a thermal spectrum caused by cosmic strings is estimated to scale as (GNμ)2z2, where GN is Newton’s constant, μ is the string tension, and z is the cosmological redshift after which spectral distortions can survive. This effect is large enough to potentially be of observational interest.

  2. String field theory vertex from integrability

    NASA Astrophysics Data System (ADS)

    Bajnok, Zoltan; Janik, Romuald A.

    2015-04-01

    We propose a framework for computing the (light cone) string field theory vertex in the case when the string worldsheet QFT is a generic integrable theory. The prime example and ultimate goal would be the AdS 5 S 5 superstring theory cubic string vertex and the chief application will be to use this framework as a formulation for SYM theory OPE coefficients valid at any coupling up to wrapping corrections. In this paper we propose integrability axioms for the vertex, illustrate them on the example of the pp-wave string field theory and also uncover similar structures in weak coupling computations of OPE coefficients.

  3. String Theory and Gauge Theories (Strings, Gravity, and the Large N Limit of Gauge Theories)

    SciTech Connect

    Maldacena, Juan

    2002-02-20

    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.

  4. Rod operated rotary well valve

    SciTech Connect

    Fredd, J.V.

    1980-10-28

    A well valve for use in a tubing string in a well bore of an oil or gas well to isolate a lower portion of the well bore below a packer including a body having a longitudinal bore therethrough connectible in a well tubing string, a lower annular valve seat supported in the body for limited sliding movement, fluid seal means between the lower valve seat and the body, an upper annular valve seat supported in longitudinal spaced relation from the lower valve seat within the body, a ball valve member supported for rotation between opened and closed positions between the valve seats, pivot members secured with the ball valve member for rotating the valve member, and a longitudinally movable operator member coupled with the pivot members for moving the pivot members longitudinally while permitting the members to traverse an arcuate path as the ball valve member rotates between open and closed positions. The valve seals both upwardly and downwardly and is opened and closed without longitudinal travel of either seat or the ball valve member. The valve is useful in various types of well installations for production and testing procedures and is operable by manipulation of operator means coupled into the valve from an upper tubing string.

  5. Patterns of Larval Sucker Emigration from the Sprague and Lower Williamson Rivers of the Upper Klamath Basin, Oregon, Prior to the Removal of Chiloquin Dam - 2006 Annual Report

    USGS Publications Warehouse

    Ellsworth, Craig M.; Tyler, Torrey J.; VanderKooi, Scott P.; Markle, Douglas F.

    2009-01-01

    In 2006, we collected larval Lost River sucker Deltistes luxatus (LRS), shortnose sucker Chasmistes brevirostris (SNS), and Klamath largescale sucker Catostomus snyderi (KLS) emigrating from spawning areas in the Williamson and Sprague Rivers. This work is part of a multi-year effort to characterize the relative abundance, drift timing, and length frequencies of larval suckers in this watershed prior to the removal of Chiloquin Dam on the lower Sprague River. Additional larval drift samples were collected from the Fremont Bridge on Lakeshore Drive on the south end of Upper Klamath Lake near its outlet to the Link River. Because of difficulties in distinguishing KLS larvae from SNS larvae, individuals identified as either of these two species were grouped together and reported as KLS-SNS in this report. We found that larval densities varied by site with the highest densities being collected at the most upstream site on the Sprague River at river kilometer (rkm) 108.0 near Beatty, Oregon (Beatty), and the most downstream sites near Chiloquin, Oregon; one site on the Sprague River at rkm 0.7 (Chiloquin) and the other site on the Williamson River at rkm 7.4 (Williamson). Larval catches were relatively small and sporadic at two other sites on the Sprague River located between Chiloquin and Beatty (Power Station at rkm 9.5 and Lone Pine at rkm 52.7) and one site on the Sycan River at rkm 4.7. Most larvae (79 percent) collected in 2006 were identified as LRS. More larvae and eggs were collected at Chiloquin than at any other site. The seasonal timing of larval drift varied by location; larvae generally were captured earlier at upstream sites than at downstream sites. Cumulative catch percentages of drifting larvae suggest that larval LRS emigrated earlier than KLS-SNS larvae at every site. Drift of LRS larvae at Beatty began 3 to 4 weeks earlier than at Chiloquin or Williamson. At Chiloquin, peak larval catches occurred 3 and 5 weeks after peak egg catches. The daily peak in larval drift at Chiloquin occurred approximately 1.5 to 2.0 hours after sunset. Nightly peak larval drift varied by location; larvae were captured earlier in the evening at sites closer to known spawning locations than sites farther away from these areas. The highest numerical catches of sucker-sized eggs were at Chiloquin indicating that this site is in close proximity to a spawning area. Numerical catches of older, more developed larval and juvenile suckers also were highest at Chiloquin. This may be due to the turbulent nature of this site, which could have swept larger fish into the drift. Proportional catches of older, more developed larval and juvenile suckers were highest at Sycan, Lone Pine, Power Station, and Fremont Bridge. This indicates these sites are located nearer to sucker nursery areas rather than spawning areas. Very few larval LRS were collected at Fremont Bridge at the south end of Upper Klamath Lake. Larval KLS-SNS densities at Fremont Bridge were the third highest of the seven sampling sites. Peak drift of larval KLS-SNS at Fremont Bridge occurred the week after peak drift of larval KLS-SNS at Williamson. Although inter-annual variation continues to appear in the larval drift data, our results continue to show consistent patterns of larval emigration in the drainage basin. In combination with data collected from the spawning movements and destinations of radio-tagged and PIT-tagged adult suckers, this larval drift data will provide a baseline standard by which to determine the effects of dam removal on the spawning distribution of endangered Klamath Basin suckers in the Sprague River.

  6. Bosonic and Baryonic String Theory in Quantum Chromodynamics

    SciTech Connect

    Kuti, Julius

    2007-02-27

    Bosonic string formation in gauge theories is reviewed with particular attention to the confining flux in lattice QCD and its effective string theory description. Recent results on the Casimir energy of the ground state and the string excitation spectrum are analyzed in the Dirichlet string limit of large separation between static sources. The closed string-soliton (torelon) with electric flux winding around a compact dimension is discussed and a new bound state tower spectrum at baryon string junctions is presented.

  7. The size of rod signals

    PubMed Central

    Alpern, M.; Rushton, W. A. H.; Torii, S.

    1970-01-01

    1. This investigation is based upon Alpern's (1965) contrast flash observations. The threshold for the test flash ? (Fig. 2a) is raised if a second flash ? falls on the annular surround. Moreover, if ? excites rods at threshold, it is only the rods in the surround that contribute to the threshold rise. 2. The possibility that the rise in ? threshold might be due to light physically scattered from surround to centre we exclude by several different experiments. We conclude (Fig. 1b) that the ? flash sets up a nerve signal N which is conducted to some place C where it inhibits the signal from the centre. 3. If the luminous surround, instead of being a full circle (Fig. 2a) consists only of the sectors shown black in Fig. 2b, that occupy 1/m of the surround area, it is found (in the physiological range) that the light/area on those sectors must be m times as great to produce the same threshold rise at centre, i.e. the total surround illumination must remain the same. 4. This result would obviously follow if N, the inhibitory nerve signal, were proportional to the total surround illumination. We have established the converse; the signal must be proportional to the quantum catch. 5. Light can be increased indefinitely, nerve signals cannot. When ? increases sufficiently, N saturates in the same way that S-potentials and receptor potentials saturate, namely according to N = ?/(? + ?) where ?, the semi-saturation constant is about 200 td sec, or 800 quanta absorbed per rod per flash. 6. Thus the nerve signal N is proportional to the quantum catch over 4 log units in the physiological range, namely from 1 quantum per 100 rods to 100 quanta per rod per flash. Above this for another 2 log units N continues to increase, but now more slowly, after the manner of S-potentials and receptor potentials. PMID:5498455

  8. Exposure to bleached kraft pulp mill effluent disrupts the pituitary-gonadal axis of white sucker at multiple sites

    SciTech Connect

    Van Der Kraak, G.J.; Munkittrick, K.R.; McMaster, M.E.; Portt, C.B.; Chang, J.P. )

    1992-08-01

    Recent studies have demonstrated reproductive problems in white sucker (Catostomus commersoni) exposed to bleached kraft pulp mill effluent (BKME) at Jackfish Bay on Lake Superior. These fish exhibit delayed sexual maturity, reduced gonadal size, reduced secondary sexual characteristics, and circulating steroid levels depressed relative to those of reference populations. The present studies were designed to evaluate sites in the pituitary-gonadal axis of prespawning white sucker affected by BKME exposure. At the time of entry to the spawning stream, plasma levels of immunoreactive gonadotropin (GtH)-II (LH-type GtH) in male and female white sucker were 30- and 50-fold lower, respectively, than the levels in fish from a reference site. A single intraperitoneal injection of D-Arg6, Pro9N-Et sGnRH (sGnRH-A, 0.1 mg/kg) increased plasma GtH levels in male and female fish at both sites, although the magnitude of the response was greatly reduced in BKME-exposed fish. Fish at the BKME site did not ovulate in response to sGnRH-A, while 10 of 10 fish from the reference site ovulated within 6 hr. Plasma 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-P) levels were depressed in BKME-exposed fish and unlike fish at the reference site, failed to increase in response to sGnRH-A. Testosterone levels in both sexes and 11-ketostestosterone levels in males were elevated in fish from the reference site but were not further increased by GnRH treatment. In contrast, BKME-exposed fish exhibit a transitory increase in testosterone levels in response to the GnRH analog. In vitro incubations of ovarian follicles obtained from fish at the BKME site revealed depressed basal secretion of testosterone and 17,20 beta-P and reduced responsiveness to the GtH analog human chorionic gonadotropin and to forskolin, a direct activator of adenylate cyclase.

  9. Melt behavior of aluminum clad rods

    SciTech Connect

    Geiger, G.T.; Long, T.A.; DeWald, A.B. Jr.

    1994-08-01

    Since the Li-Al alloy cores in control rods used to control production reactors are susceptible to corrosion by heavy water, they were clad with Al. This paper reports results of an experimental and numerical study of the behavior of control rods heated to the point of clad and rod-core failure. Results show that the core of the rod melts first; the clad fails only after significant additional heating. Once the rod breaks and drops to the bottom of the quartz tube in the furnace, the lower section of the rod fails by ``poker-chipping`` downward as the topmost portion fails before the portion below it. Part of the core in the remaining top of the rod relocates immediately after rod separation, leaving a hollow tube of Al which also melts upon further heating.

  10. Genetics Home Reference: Intranuclear rod myopathy

    MedlinePLUS

    ... that cause intranuclear rod myopathy result in the accumulation of rods of skeletal ?-actin in the ... the nucleus and the cytoplasm, resulting in the accumulation of actin in the nucleus and the formation ...

  11. Genetics Home Reference: Cone-rod dystrophy

    MedlinePLUS

    ... common cause of autosomal recessive cone-rod dystrophy, accounting for 30 to 60 percent of cases. At ... Where can I find information about diagnosis or management of cone-rod dystrophy? These resources address the ...

  12. Control rods in LMFBRs: a physics assessment

    SciTech Connect

    McFarlane, H.F.; Collins, P.J.

    1982-08-01

    This physics assessment is based on roughly 300 control rod worth measurements in ZPPR from 1972 to 1981. All ZPPR assemblies simulated mixed-oxide LMFBRs, representing sizes of 350, 700, and 900 MWe. Control rod worth measurements included single rods, various combinations of rods, and Ta and Eu rods. Additional measurements studied variations in B/sub 4/C enrichment, rod interaction effects, variations in rod geometry, neutron streaming in sodium-filled channels, and axial worth profiles. Analyses were done with design-equivalent methods, using ENDF/B Version IV data. Some computations for the sensitivities to approximations in the methods have been included. Comparisons of these analyses with the experiments have allowed the status of control rod physics in the US to be clearly defined.

  13. Cosmic string evolution in higher dimensions

    SciTech Connect

    Avgoustidis, A.; Shellard, E.P.S.

    2005-06-15

    We obtain the equations of motion for cosmic strings in extensions of the 3+1 Friedmann-Robertson-Walker (FRW) model with extra dimensions. From these we derive a generalization of the velocity-dependent one-scale model for cosmic string network evolution which we apply, first, to a higher-dimensional isotropic D+1 FRW model and, second, to a 3+1 FRW model with static flat extra dimensions. In the former case the string network does not achieve a scaling regime because of the diminishing rate of string intersections (D>3), but this can be avoided in the latter case by considering compact, small extra dimensions, for which there is a reduced but still appreciable string intercommuting probability. We note that the velocity components lying in the three expanding dimensions are Hubble damped, whereas those in the static extra dimensions are only very weakly damped. This leads to the pathological possibility, in principle, that string motion in the three infinite dimensions can come to a halt preventing the strings from intersecting, with the result that scaling is not achieved and the strings irreversibly dominate the early universe. We note criteria by which this can be avoided, notably if the spatial structure of the network becomes essentially three-dimensional, as is expected for string networks produced in brane inflation. Applying our model to a brane inflation setting, we find scaling solutions in which the effective 3D string motion does not necessarily stop, but it is slowed down because of the excitations trapped in the extra dimensions. These effects are likely to influence cosmic string network evolution for a long period after formation and we discuss their more general implications.

  14. 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.

  15. Supersymmetry breaking in string theory

    SciTech Connect

    Dixon, L.J.

    1990-04-01

    I briefly review the problems with previous investigations of supersymmetry breaking in string theory --- at tree-level, at one-loop, and non-perturbatively. A variant of the original non-perturbative scenario is proposed, in which gaugino condensation takes place in two different strongly-interacting hidden-sector gauge groups. In the new scenario it is possible to generate a large hierarchy of mass scale and to simultaneously stabilize the dilaton at a large expectation value (weak coupling). However, it is still uncertain whether supersymmetry is broken in such a vacuum. 26 refs.

  16. 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.

  17. 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.

  18. 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.

  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. 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)

  1. 49 CFR 236.793 - Rod, lock.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Rod, lock. 236.793 Section 236.793 Transportation... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Definitions 236.793 Rod, lock. A rod... may extend when the switch points or derail are in the normal or reverse position....

  2. 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.

  3. Melt dumping in string stabilized ribbon growth

    DOEpatents

    Sachs, Emanuel M. (42 Old Middlesex Rd., Belmont, MA 02178)

    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.

  4. Quantum space foam and string theory

    SciTech Connect

    Nekrasov, Nikita

    2006-11-03

    String theory is originally defined as a modification of the Feynman rules in perturbation theory. It contains gravity in its perturbative spectrum. We review some recent developments which demonstrate that nonperturbative effects of quantum gravity, such as spacetime foam, arise in string theory as well.Prepared for the proceedings of 'Albert Einstein Century Conference' , Paris July 2005.

  5. Sewing String Tree Vertices with Ghosts

    NASA Astrophysics Data System (ADS)

    Sandoval Junior, Leonidas

    2002-03-01

    It is shown how to sew string vertices with ghosts at tree level in order to produce new tree vertices using the Group Theoretic approach to String Theory. It is then verified the BRST invariance of the sewn vertex and shown that it has the correct ghost number.

  6. Early Adolescence: The Great String Drop.

    ERIC Educational Resources Information Center

    Leyden, Michael, Ed.

    1985-01-01

    Provides guidelines for simple acceleration experiments with string and attached weights as a means to stimulate the reticular activating system (RAS) of the human brain. Several methods (discrepant events, curiosity, choices, and doubt) are suggested for promoting RAS high-level thought. String drop experiments provide concrete experiences with

  7. 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

  8. 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.

  9. String Theory and the Scientific Method

    NASA Astrophysics Data System (ADS)

    Dawid, Richard

    2015-01-01

    Introduction; Part I. Delimiting the Unconceived: 1. String theory; 2. The conceptual framework; 3. The assessment of scientific underdetermination in string theory; Part II. A Wider Perspective: 4. The dynamics of high energy physics; 5. Scientific underdetermination in physics and beyond; Part III. Physics and Truth: 6. Final theory claims; 7. An altered perspective on scientific realism; References; Index.

  10. Rotating cosmic strings and gravitational soliton waves

    SciTech Connect

    Economou, A.; Tsoubelis, D.

    1988-07-15

    Using the Belinsky-Zakharov inverse scattering method, a four-parameter family of cylindrically symmetric solutions of Einstein's vacuum equations is obtained. They are of Petrov type D and, for a certain range of the parameters, represent solitonlike gravitational waves interacting with a straight-line cosmic string. Their interpretation as rotating cosmic strings occupying the axis of symmetry is also investigated.

  11. 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.

  12. Natural language insensitive short textual string compression

    NASA Astrophysics Data System (ADS)

    Constantinescu, Cornel; Trelewicz, Jennifer Q.; Arps, Ronald B.

    2004-01-01

    There are applications (such as Internet search engines) where short textual strings, for example abstracts or pieces of Web pages, need to be compressed independently of each other. The usual adaptive compression algorithms perform poorly on these short strings due to the lack of necessary data to learn. In this manuscript, we introduce a compression algorithm targeting short text strings; e.g., containing a few hundred symbols. We also target natural language insensitivity, to facilitate its robust compression and fast implementation. The algorithm is based on the following findings. Applying the move-to-front transform (MTFT) after the Burrows-Wheeler transform (BWT) brings the short textual strings to a "normalized form" where the distribution of the resulting "ranks" has a shape similar over the set of natural language strings. This facilitates the use of a static coding method with few variations, which we call shortBWT, where no on-line learning is needed, to encode the ranks. Finally, for short strings, shortBWT runs very fast because the strings fit into the cache of most current computers. The introduction for this paper will review the mathematical bases of BWT and MTF, it will also review our recently published metric for rapidly pre-characterizing the compressibility of such short textual strings when using these transforms.

  13. 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…

  14. 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…

  15. 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

  16. First quantized noncritical relativistic Polyakov string

    NASA Astrophysics Data System (ADS)

    Jaskolski, Z.; Meissner, K. A.

    1994-01-01

    The first quantization of the relativistic Brink-DiVecchia Howe-Polyakov (BDHP) string in the range 1 less than d less than 25 is considered. It is shown that using the Polyakov sum over bordered surfaces in the Feynman path integral quantization scheme one gets a consistent quantum mechanics of relativistic 1-dim extended objects in the range 1 less than d less than 25. In particular, the BDHP string propagator is exactly calculated for arbitrary initial and final string configurations and the Hilbert space of physical states of noncritical BDHP string is explicitly constructed. The resulting theory is equivalent to the Fairlie-Chodos-Thorn massive string model. In contrast to the conventional conformal field theory approach to noncritical string and random surfaces in the Euclidean target space the path integral formulation of the Fairlie-Chodos-Thorn string obtained in this paper does not rely on the principle of conformal invariance. Some consequences of this feature for constructing a consistent relativistic string theory based on the 'splitting-joining' interaction are discussed.

  17. First quantized noncritical relativistic Polyakov string

    NASA Astrophysics Data System (ADS)

    Jasklski, Zbigniew; Meissner, Krzysztof A.

    1994-10-01

    The first quantization of the relativistic Brink-DiVecchia-Howe-Polyakov (BDHP) string in the range 1 < d < 25 is considered. It is shown that using the Polyakov sum over bordered surfaces in the Feynman path integral quantization scheme one gets a consistent quantum mechanics of relativistic one-dimensional extended objects in the range 1 < d < 25. In particular the BDHP string propagator is exactly calculated for arbitrary initial and final string configurations and the Hilbert space of physical states of noncritical BDHP string is explicitly constructed. The resulting theory is equivalent to the Fairlie-Chodos-Thorn massive string model. In contrast to the conventional conformal field theory approach to noncritical string and random surfaces in the Euclidean target space the path integral formulation of the Fairlie-Chodos-Thorn string obtained in this paper does not rely on the principle of conformal invariance. Some consequences of this feature for constructing a consistent relativistic string theory based on the "splitting-joining" interaction are discussed.

  18. 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

  19. 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

  20. Drill strings take on new look

    SciTech Connect

    Moore, S.D.

    1986-04-01

    Over the years, drillers and operators have placed increasing demands on the drill string. As a results, components of the drill string have become more diverse in application and more durable and reliable in performance. Even today's depressed prices, several $100,000 worth of drill string equipment can be in the hole at one time. The combination of downhole mud motor, MWD tool, and high-performance PDC bit provides the operator and driller with plenty of firepower to drill ahead-but at a hefty price. Numerous laboratory and field studies have been carried out to gain a better understanding of a drill string's performance and how to improve drilling operations. More research efforts in the coming years will be directed toward downhole problems. If penetration rates can be increased, while drilling time and costs reduced, drilling becomes more economical and attractive. This article is a short synopsis of various new technologies affecting today's drill string.