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1

Numerical modelling of longitudinal vibrations of a sucker rod string  

NASA Astrophysics Data System (ADS)

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.

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

2010-03-01

2

Analysis of sucker rod and sinkerbar failures.  

National Technical Information Service (NTIS)

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 microstructur...

J. R. Waggoner R. G. Buchheit

1993-01-01

3

Analysis of sucker rod and sinkerbar failures.  

National Technical Information Service (NTIS)

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. Metallogra...

J. R. Waggoner R. G. Buchheit

1992-01-01

4

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

5

Rod coupling for oil well sucker rods and the like  

SciTech Connect

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.

Bowers, R.

1986-07-29

6

Enhancement of fiberglass sucker-rod design is offered  

SciTech Connect

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.

Hallden, D.F.

1985-09-30

7

Fluid Dynamics in Sucker Rod Pumps.  

National Technical Information Service (NTIS)

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...

R. P. Cutler A. J. Mansure

1999-01-01

8

Fluid Dynamics in Sucker Rod Pumps.  

National Technical Information Service (NTIS)

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...

R. P. Cutler A. J. Mansure

1999-01-01

9

Fluid Dynamics in Sucker Rod Pumps  

SciTech Connect

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.

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

1999-01-14

10

Gas Interference in Sucker Rod Pump  

NASA Astrophysics Data System (ADS)

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.

Samad, Abdus

2010-10-01

11

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

National Technical Information Service (NTIS)

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 modifi...

E. L. Hoffman

1997-01-01

12

Mechanical performance of fiberglass laminates for sucker rod applications  

SciTech Connect

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.

Gauchel, J.V.

1985-01-01

13

Super hi-strength sucker rods  

Microsoft Academic Search

Metallurgical and field testing of pumping rods which led to the development of the Electra series of rods is described. There are now operating over 2 million ft of Electra I's and II's in the U.S. and Canada. Failures have been minimal. There have been about 24 body breaks caused mostly by mechanical damage such as nicks or bending. At

Metters

1973-01-01

14

Radial pressure sensor of sucker rod based on LabVIEW  

NASA Astrophysics Data System (ADS)

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.

Wang, Zhongyu; Yan, Hu; Li, Qiang

2013-10-01

15

Enhanced oil recovery. Operators fight corrosion with fiberglass injection pipe, casing and sucker rods  

SciTech Connect

Operators have been fighting corrosion in the Permian Basin since the first oil (along with saltwater and H/sub 2/S gas) was produced. However, with ever- increasing attempts to squeeze more oil out of the ground through secondary and tertiary recovery methods, a new high in corrosive properties has been reached. It starts when waterflooding is introduced, and reaches its maximum effect when CO/sub 2/ is injected to recover tertiary oil. Corrosion strikes whenever contaminated water, H/sub 2/S or wet CO/sub 2/ is injected or produced. Even the dry CO/sub 2/ used in most tertiary injection projects becomes extremely corrosive when it contacts water or wet surfaces. Amoco is designing its injection and production facilities to be corrosion resistant. A major element in the fight against corrosion at Scurry Area Canyon Reef Operators Committee in the Kelly-Snyder field in Scurry County, Texas, has been the use of glass fiber-reinforced plastic (FRP) materials in high pressure surface injection pipes, saltwater gathering lines, casing liners and sucker rods. Amoco has used fiberglass flowlines for injection wells in waterflood operations as well as FRP sucker rods in producing wells.

Wash, R.

1983-04-01

16

Rods-on-string idealization captures semiflexible filament dynamics  

NASA Astrophysics Data System (ADS)

We present an approach to modeling the two-dimensional Brownian dynamics of semiflexible filaments in the worm-model description as uniform, isotropic, and continuously flexible. Experimental observations increasingly show that the mechanical behavior of semiflexible filament networks departs from conventional knowledge. A force-balance-based dynamic simulation of the filament networks has multiple advantages as an approach to understanding their anomalous mechanics. However, a major disadvantage is the difficulty of capturing filament hydrodynamics and bending mechanics in a computationally efficient and physically consistent manner. To that end, we propose a strategy for modeling semiflexible filaments which involves idealizing a semiflexible filament as a contiguous string of flexible rods, and considering the Brownian forces on it as Einsteinian-like point normal and tangential forces. By idealizing the filament as a string of rods, we avoid the complex hydrodynamic treatment involved in beads-on-string idealizations, and implement large-deflection beam mechanics and filament inextensibility in a natural manner, while reducing the computational size of the problem. By considering the Brownian forces as point normal and tangential forces, we decompose the Brownian forces on straight and curved segments into a combination of classical resultant forces and couples whose distribution is shown to be governed by the rod diffusion coefficients. The decomposition allows solution of the Euler beam equations to second-order continuity between segments and fifth-order continuity within segments. We show that the approach is physically consistent by capturing multiple Brownian phenomena ranging from the rigid to the semiflexible limit: the translational and rotational diffusion of rigid rods; the thermal fluctuation of semirigid cantilever filaments; and the shape, bending, and time relaxation of freely diffusing, semiflexible actin filaments.

Chandran, Preethi L.; Mofrad, Mohammad R. K.

2009-01-01

17

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

PubMed

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

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

2009-02-01

18

Shark Suckers: Remoras  

NSDL National Science Digital Library

Sharks and many other large ocean animals have sucker-equipped fish called remoras sticking to them. What are the remoras doing? Do they harm the sharks? In this video, Jonathan goes on a mission to investigate remoras and their role in the food web. He even sticks one on himself. Please see the accompanying study guide for educational objectives and discussion points.

Productions, Jonathan B.

2011-03-10

19

Artificial adhesion mechanisms inspired by octopus suckers  

Microsoft Academic Search

We present the design and development of novel suction cups inspired by the octopus suckers. Octopuses use suckers for remarkable tasks and they are capable to obtain a good reversible wet adhesion on different substrates. We investigated the suckers morphology that allow octopus to attach them to different wet surfaces to obtain the benchmarks for new suction cups showing similar

Francesca Tramacere; Lucia Beccai; Fabio Mattioli; Edoardo Sinibaldi; Barbara Mazzolai

2012-01-01

20

Morphometric and Meristic Differences among Bluehead Suckers, Flannelmouth Suckers, White Suckers, and Their Hybrids: Tools for the Management of Native Species in the Upper Colorado River Basin  

Microsoft Academic Search

Hybridization with nonnative fishes is a major factor influencing the status of native catostomids in the Colorado River basin. In Wyoming, hybridization with nonnative white suckers Catostomus commersonii is a particular concern in the conservation of native bluehead suckers C. discobolus and flannelmouth suckers C. latipinnis. The purpose of this study was to describe the meristic and morphometric characteristics of

Michael C. Quist; Michael R. Bower; Wayne A. Hubert; Thomas L. Parchman; David B. McDonald

2009-01-01

21

Rod guide/paraffin scraper  

SciTech Connect

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.

Mabry, J.F.

1991-02-26

22

Sucker-like structures on the pathogenic amoeba Naegleria fowleri.  

PubMed Central

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

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

1984-01-01

23

Predation on lake whitefish eggs by longnose suckers  

USGS Publications Warehouse

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.

Nester, Robert T.; Poe, Thomas P.

1984-01-01

24

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

USGS Publications Warehouse

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.

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

2008-01-01

25

Patterns of Intra- and Interspecies Genetic Diversity in Klamath River Basin Suckers  

Microsoft Academic Search

The Klamath River basin, Oregon, is home to four catostomid species: The Klamath smallscale sucker Catostomus rimiculus, the Klamath largescale sucker Catostomus snyderi, the shortnose sucker Chasmistes brevirostris, and the Lost River sucker Deltistes luxatus. A decline in Lost River and shortnose sucker abundances resulted in these species being listed as endangered under the U.S. Endangered Species Act in 1988.

Gregory J. Tranah; Bernie May

2006-01-01

26

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...

27

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

PubMed Central

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.

Appel, Esther

2014-01-01

28

Structure and mechanical properties of Octopus vulgaris suckers  

PubMed Central

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.

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

2014-01-01

29

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

Microsoft Academic Search

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

Rdissi

1984-01-01

30

String Vibrations  

NSDL National Science Digital Library

This site, by Andrew Davidhazy at the Rochester Institute of Technology, describes how to make interesting and artistic photographs of a vibrating string. Davidhazy explains how the string is vibrated, how the string is lit, and even the exposure time and the effect it has on the resulting image. Four images of the vibrating string are included.

2006-12-29

31

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

USGS Publications Warehouse

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.

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

2008-01-01

32

Habitat features affect bluehead sucker, flannelmouth sucker, and roundtail chub across a headwater tributary system in the Colorado River Basin  

USGS Publications Warehouse

We assessed the distributions of three species of conservation concern, bluehead sucker (Catostomus discobolus), flannelmouth sucker (Catostomus latipinnis), and roundtail chub (Gila robusta), relative to habitat features across a headwater tributary system of the Colorado River basin in Wyoming. We studied the upper Muddy Creek watershed, Carbon County, portions of which experience intermittent flows during late summer and early fall. Fish and habitat were sampled from 57 randomly-selected, 200-m reaches and 416 habitat units (i.e., pools, glides, or runs) during the summer and fall of 2003 and 2004. Among reaches, the occurrences of adults and juveniles of all three species were positively related to mean wetted width and the surface area of pool habitat, and the occurrences of adult bluehead sucker and roundtail chub were also positively related to the abundance of rock substrate. Only juvenile bluehead sucker appeared to be negatively influenced by the proportion of a reach that was dry at the time of sampling. Within individual pools, glides, and runs, the occurrences of adults and juveniles of all three species were positively related to surface area and maximum depth, and occurrences of bluehead sucker and flannelmouth sucker juveniles were more probable in pools than in glides or runs.

Bower, M. R.; Hubert, W. A.; Rahel, F. J.

2008-01-01

33

The Morphology and Adhesion Mechanism of Octopus vulgaris Suckers  

PubMed Central

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.

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

2013-01-01

34

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

PubMed

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

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

2002-05-27

35

Commentary: selenium study on endangered razorback sucker is flawed  

Microsoft Academic Search

The razorback sucker (Xyrauchen texanus) is listed as federally endangered throughout its range. A massive recovery effort by the Recovery Implementation Program for Endangered Fish Species in the Upper Colorado River Basin has focused its efforts in the upper Colorado River. The upper Colorado River basin also has two locations that have been identified by the National Irrigation Water Quality

Steven J. Hamilton

2005-01-01

36

Commentary: selenium study on endangered razorback sucker is flawed.  

PubMed

The razorback sucker (Xyrauchen texanus) is listed as federally endangered throughout its range. A massive recovery effort by the Recovery Implementation Program for Endangered Fish Species in the Upper Colorado River Basin has focused its efforts in the upper Colorado River. The upper Colorado River basin also has two locations that have been identified by the National Irrigation Water Quality Program as having substantial selenium contamination. Selenium is toxic to fishes, affecting reproductive success. Thus, there is concern about potential effects of selenium on the endangered razorback sucker. Two sets of studies have investigated the effects of selenium on razorback suckers, but study results are conflicting. This commentary evaluates studies that claim selenium is not a problem for razorback sucker. We find that study bias was so pervasive that purported conclusions were unwarranted. Contaminated control water, older life stages of fish tested, lack of methodology for analysis of selenium in water, diet, or fish, use of rotifer food, low feeding rates, low growth rates of fish, and improper storage of site waters resulted in an apparent erroneous linkage of high selenium in whole-body residues with no adverse effects. PMID:15922797

Hamilton, Steven J

2005-07-01

37

Rod Fractions  

NSDL National Science Digital Library

This problem allows students an opportunity to think about fraction comparisons and equivalencies in a different way using interactive rods. Students are given two different fraction rods of unknown lengths and the goal is to find out what fraction the shorter rod is of the longer rod. A Teacher's Notes page, hints, solution, and printable pages are provided.

2005-10-01

38

Bowed Strings  

NASA Astrophysics Data System (ADS)

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

Rossing, Thomas D.; Hanson, Roger J.

39

Skyrme Strings  

NASA Astrophysics Data System (ADS)

We construct nontopological string solutions with U(1) Noether charge in the Skyrme model with a pion mass term, and examine their stability by taking linear perturbations. The solution exhibits a critical angular velocity beyond which the configuration energetically prefers to decay by emitting pions. This critical point is observed as a cusp in the relation between energy and charge. We find that the maximum length for the string to be stable is comparable to the size of one skyrmion. Beyond the length, it is unstable to decay. This instability raises the possiblity of dynamical realization of Skyrme strings from monopole strings inside a domain wall.

Nitta, M.; Shiiki, N.

2008-05-01

40

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 ...

41

Cosmic strings  

NASA Technical Reports Server (NTRS)

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.

Bennett, David P.

1988-01-01

42

Cosmic strings  

SciTech Connect

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.

Bennett, D.P.

1988-07-01

43

String Shapes  

NSDL National Science Digital Library

In this activity, learners work together to make polygons (many-sided shapes) with string. Learners sit on the floor and hold onto a piece of string slid between their thumbs and index fingers. Learners explore how many different kinds of triangles and other shapes they can make by changing their hand positions. Use this activity to help learners explore polygons including convex and concave polygons and vertices.

Exploratorium

2010-01-01

44

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...

45

Signals controlling root suckering and adventitious shoot formation in aspen (Populus tremuloides).  

PubMed

We determined the effects of removal of leaves, stem axillary buds, or the entire shoot on root suckering (adventitious shoot formation by roots) and basal stem sprouts in 3- and 4-year-old potted seedlings of aspen (Populus tremuloides Michx.). The greatest number of root suckers (67.9 +/- 8.5 per plant) emerged after excision of the entire shoot. Defoliated and debudded stems were the major source of inhibitory agents for root suckering, although axillary buds and developing new leaves also exerted a significant inhibitory effect. Removal of mature leaves had only a minor effect on root suckering. Removal of a continuous band of bark (girdling) at the base of the stem consistently stimulated growth of adventitious shoots from the stem below the girdle and occasionally promoted root suckering. Exogenous application of indole-3-acetic acid to excised stumps inhibited root suckering and basal stem sprouting. Naphthylphthalamic acid (NPA), an auxin polar transport inhibitor, had no effect on root suckering or stem sprouting when it was applied to the bark of the basal stem. However, NPA significantly increased root suckering when it was applied to the exposed surface of xylem after girdling. These results suggest that polar transport of auxin in the xylem parenchyma is an important inhibitor of root suckering. On decapitated stems, vacuum extraction of xylem sap from the root system lowered the frequency of root suckering compared with decapitation alone, indicating that substance(s) originating in the root system also play a significant role in controlling root suckering. PMID:16452082

Wan, Xianchong; Landhäusser, Simon M; Lieffers, Victor J; Zwiazek, Janusz J

2006-05-01

46

Food limited survival of larval razorback sucker, Xyrauchen texanus , in the laboratory  

Microsoft Academic Search

Razorback suckers in Lake Mohave, Arizona-Nevada, are suffering recruitment failure. Concomitantly, lake zooplankton levels are low and variable. We test, under laboratory conditions, the possibility that starvation is a cause of low recruitment. Razorback sucker larvae that were starved, received food too late, or were provided with insufficient food died between 20 and 30 d after hatching. Yolk absorption was

Diana Papoulias; Wendell L. Minckley

1990-01-01

47

Cosmic Strings and Superconducting Cosmic Strings.  

National Technical Information Service (NTIS)

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 ...

E. Copeland

1988-01-01

48

Cosmic strings and superconducting cosmic strings  

NASA Technical Reports Server (NTRS)

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.

Copeland, Edmund

1988-01-01

49

Plucked Strings  

NASA Astrophysics Data System (ADS)

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

Rossing, Thomas D.

50

String Theory  

NSDL National Science Digital Library

While few people toss around terms like Astroparticle Physics and Superstring Theory, we've all found ourselves staring out in to space on a starry night wondering what's out there, why it's arranged the way it is, and where it all came from. For some, it simply comes down to strings. This September 2, 2003 New York Times article does a good job of summarizing the history and specifics of string theory and the paradox of its many offerings (1). One-time egistration is required to access any New York Times articles. The next site is the homepage of the Kavli Institute for Theoretical Physics at the University of California Santa Barbara and home to some of the most intense thinking with regards to theoretical physics in the world (2). Going from highly technical to more popularly palatable, NOVA offers the third site (3 ). Called, The Elegant Universe, the upcoming NOVA special is based on Columbia University professor Brian Greene's highly acclaimed book of the same title. As the site states, "Eleven dimensions, parallel universes, and a world made out of strings. It's not science fiction, it's string theory." The next site takes you directly to the virtual home of string theory (4 ). Here you will find the basics on the topic as well as what scientists have found so far and where they're headed next. Probably the most definitive site devoted to the topic. The fifth site is another informative look at superstring theory and is provided by John Pierre at MIT. While a very basic Web site, in terms of design, it offers a great tutorial on strings in addition to a glossary and reference list (5 ). The final link (6 ) will take you "Beyond Einstein, from the Big Bang to Black Holes." The site, provided by NASA, offers insights into the history and structure of the universe.

Morgan, John P.

51

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

USGS Publications Warehouse

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.

Hewitt, David A.;Hayes, Brian S.

2013-01-01

52

Test report for drill string seal pressure test  

SciTech Connect

A basic question was asked concerning the drill string which is used in rotary Mode coring operations: ``...what is the volume leak rate loss in a drill rod string under varying condiditons of the joint boxes and pins being either dry or coated with lubricant...``. A Variation of this was to either have an o-ring installed or absent on the drill rod that was grooved on the pin. A series of tests were run with both the o-ring grooved Longyear drill rod and the plain pin end rod manufactured by Diamond Drill. Test results show that drill rod leakage of both types is lowered dramatically when thread lubricant is applied to the threaded joints and the joints made up tight. The Diamond Drill rod with no o-ring groove has virtually no leakage when used with thread lubricant and the joints are properly tightened.

McCormick, J.F.

1996-02-06

53

String Theory  

Microsoft Academic Search

For each $n > 0$, two alternative axiomatizations of the theory of strings over $n$ alphabetic characters are presented. One class of axiomatizations derives from Tarski's system of the Wahrheitsbegriff and uses the $n$ characters and concatenation as primitives. The other class involves using $n$ character-prefixing operators as primitives and derives from Hermes' Semiotik. All underlying logics are second order.

John Corcoran; William Frank; Michael Maloney

1974-01-01

54

String mediated phase transitions  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

55

The "Magic" String  

ERIC Educational Resources Information Center

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…

Hoover, Todd F.

2010-01-01

56

Quasiopen string  

SciTech Connect

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.

Roy, S.M.; Singh, V.

1987-03-15

57

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

USGS Publications Warehouse

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.

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

2009-01-01

58

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...

59

Rod centralizer  

SciTech Connect

This patent describes a well tool. It includes a pump rod and a centralizer having a single piece cylindrical body rigidly mounted on the rod, an upper pair of ribs integral with an upper portion of the body and extending outwardly therefrom in opposite directions, and a lower pair of ribs integral with a lower portion of the body and extending outwardly therefrom in opposite directions. The lower pair of ribs being displaced on the body from the upper pair of ribs ninety degrees about the central longitudinal axis of the rod, the body having a circumferential intermediate portion integral with the upper and lower portions between the top ends of the lower ribs and the bottom ends of the upper pair of ribs, the intermediate portion of the body being of lower mechanical strength than the portions thereof provided with the ribs.

Sable, D.E.

1991-03-05

60

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

USGS Publications Warehouse

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.

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

1999-01-01

61

Strings and Noncommutativity  

Microsoft Academic Search

In these talks we review some of the recent results on open strings and noncommutative gauge theories, starting from the early calculations of open strings in a constant electromagnetic background. We discuss both the neutral string and the charged string. In the latter case, the scaling limit that leads to noncommutative abelian gauge theory can be generalized to a scaling

Louise Dolan; Chiara R. Nappi

2003-01-01

62

What is String Theory?  

Microsoft Academic Search

The first part is an introduction to conformal field theory and string perturbation theory. The second part deals with the search for a deeper answer to the question posed in the title. Contents: 1. Conformal Field Theory 2. String Theory 3. Vacua and Dualities 4. String Field Theory or Not String Field Theory 5. Matrix Models

Joseph Polchinski

1994-01-01

63

Constraint Reasoning Over Strings  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

64

The "Magic" String  

NSDL National Science Digital Library

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

Hoover, Todd F.

2010-10-01

65

String-driven inflation  

NASA Technical Reports Server (NTRS)

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.

Turok, Neil

1988-01-01

66

Learning String Edit Distance  

Microsoft Academic Search

In many applications, it is necessary to determine the similarity of two strings. A widely-used notion of string similarity is the edit distance: The minimum number of insertions, deletions, and substitutions required to transform one string into the other. In this report, we provide a stochastic model for string-edit distance. Our stochastic model allows us to learn a string-edit distance

Eric Sven Ristad; Peter N. Yianilos

1997-01-01

67

Coupled economic-coastline modeling with suckers and free riders  

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

68

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

PubMed

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 microg/g from Horsethief, 46 microg/g from Adobe Creek, 38 microg/g from North Pond, and 6.0 microg/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. PMID:15814308

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

2005-05-01

69

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

PubMed

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

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

2013-07-01

70

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

PubMed Central

Catostomid fishes (suckers) have duplicate copies of the growth hormone gene and other nuclear genes, due to a genome duplication event early in the group’s 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.

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

2010-01-01

71

Hydraulic well pumping apparatus  

SciTech Connect

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.

Wright, C.P.

1987-03-03

72

Regression, proliferation and development of lip papillomas in wild white suckers, Catostomus commersoni , held in the laboratory  

Microsoft Academic Search

Epizootics of skin neoplasms in teleost species have been documented within the Great Lakes region over the last decade. The white sucker,Catostomus commersoni, has been proposed as a sentinel species to monitor environmental health in these systems. The prevalence of skin neoplasia is elevated in white suckers and other fish taken from chemically polluted sites or from lake regions adjacent

Peter D. Premdas; Chris D. Metcalfe

1994-01-01

73

Determination of Upper Temperature Tolerance in June Sucker Larvae: Is the Transition to Utah Lake Temperatures a Recruitment Bottleneck?  

Microsoft Academic Search

The June sucker Chasmistes liorus is an endangered adfluvial fish species that is endemic to the Utah Lake basin. This species remains endangered due to a lack of recruitment. Anthropogenic changes to June sucker lotic and lentic habitat has likely led to recruitment failure. Changes to Utah Lake include increased water temperature, increased turbidity, and eutrophic and saline conditions. The

Kevin M. Kappenman; Molly A. H. Webb; Elijah S. Cureton; Jason Ilgen

2010-01-01

74

Tensionless Strings:  

NASA Astrophysics Data System (ADS)

We study the physical Fock space of the tensionless string theory with perimeter action, exploring its new gauge symmetry algebra. The cancellation of conformal anomaly requires the space-time to be 13-dimensional. All particles are massless and there are no tachyon states in the spectrum. The zero mode conformal operator defines the levels of the physical Fock space. All levels can be classified by the highest Casimir operator W of the little group E(11) for massless particles in 11-dimensions. The ground state is infinitely degenerated and contains massless gauge fields of arbitrary large integer spin, realizing the irreducible representations of E(11) of fixed helicity. The excitation levels realize CSR representations of little group E(11) with an infinite number of helicities. After inspection of the first excitation level, which, as we prove, is a physical null state, we conjecture that all excitation levels are physical null states. In this theory the tensor field of the second rank does not play any distinctive role and therefore one can suggest that in this model there is no gravity.

Savvidy, G. K.

75

Singing Rod  

NSDL National Science Digital Library

How can a solid metal rod be made to emit a high-pitched squeal? This material is part of a series of hands-on science activities designed to arouse student interest. Here students investigate the resonance and acoustic properties that result from stroking a solid aluminum bar and causing it to resonate. The activity includes a description, a list of science process skills and complex reasoning strategies being used, and a compilation of applicable K-12 national science education standards. Also provided are content topics, a list of necessary supplies, instructions, and presentation techniques. The content of the activity is explained, and assessment suggestions are provided.

Mid-continent Research for Education and Learning (McREL); Jacobs, Steve

2004-01-01

76

Spin-string interaction in QCD strings  

SciTech Connect

I consider the question of the interaction between a QCD string and the spin of a quark or an antiquark on whose worldline the string terminates. The problem is analyzed from the point of view of a string representation for the expectation value of a Wilson loop for a spin-half particle. A string representation of the super Wilson loop is obtained starting from an effective string representation of a Wilson Loop. The action obtained in this manner is invariant under a worldline supersymmetry and has a boundary term which contains the spin-string interaction. For rectangular loops the spin-string interaction vanishes and there is no spin-spin term in the resulting heavy quark potential. On the other hand if an allowance is made for the finite intrinsic thickness of the flux tube by assuming that the spin-string interaction takes place not just at the boundary of the string world sheet but extends to a distance of the order of the intrinsic thickness of the flux tube then we do obtain a spin-spin interaction which falls as the fifth power of the distance. Such a term was previously suggested by Kogut and Parisi in the context of a flux-tube model of confinement.

Vyas, Vikram [Physics Department St. Stephen's College, Delhi University, Delhi (India)

2008-08-15

77

Control rod cluster arrangement  

SciTech Connect

This patent describes a nuclear reactor including nuclear core which is cooled and moderated by light water, the nuclear core comprising a plurality of parallel arranged openings therethrough and interspersed among the fuel assemblies. A control rod cluster arrangement comprises load follow control rod cluster assemblies with each load follow control rod cluster assembly being adapted to slidingly fit within each of some of the fuel assemblies in the parallel arranged openings, the load follow control rod cluster assemblies each comprising a plurality of elongated parallel arranged rods attached to a single spider, and including a first group of rods and a second group of rods, the first group of rods and the second each consisting of a plurality of absorber rods. The first group of rods consist of absorber rods taken from the group consisting of B/sub 4/C, hafnium, or silver-indium-cadmium and the second group of rods consist of absorber rods each consisting of stainless steel, the first group of rods and the second group of rods each being integrally attached at all times to the single spider, the absorber rods of the second group of rods being dispersed throughout the control rod cluster assembly. The first group of rods have a first neutron capture cross section and the second group of rods have a second neutron capture cross section different from the first cross section.

Orr, W.L.; Doshi, P.K.; Mildrum, C.M.; Freeman, T.R.

1987-02-10

78

Sperm quality assessments for endangered razorback suckers Xyrauchen Texanus  

USGS Publications Warehouse

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.

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

2011-01-01

79

Sorting Symbol Strings  

ERIC Educational Resources Information Center

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

Novak, Jodie D.; Jacobs, Judith E.

2005-01-01

80

Fundamental strings in SFT  

NASA Astrophysics Data System (ADS)

In this Letter we show that vacuum string field theory contains exact solutions that we propose to interpret as macroscopic fundamental strings. They are formed by a condensate of infinitely many completely space-localized solutions (D0-branes).

Bonora, L.; Maccaferri, C.; Scherer Santos, R. J.; Tolla, D. D.

2005-07-01

81

Fundamental strings in SFT  

Microsoft Academic Search

In this Letter we show that vacuum string field theory contains exact solutions that we propose to interpret as macroscopic fundamental strings. They are formed by a condensate of infinitely many completely space-localized solutions (D0-branes).

L. Bonora; C. Maccaferri; R. J. Scherer Santos; D. D. Tolla

2005-01-01

82

Chiral (super) String Actions  

Microsoft Academic Search

We present a covariant action describing chiral bosonic string theories in space-time dimensions d<26 and a covariant (1, 0) supersymmetric action describing heterotic string theories in space-time of dimension d<10. The anomaly cancellation conditions are found. In the four-dimensional case the supersymmetric action corresponds to the SO(44) heterotic string theory.

S. M. Kuzenko; O. A. Soloviev

1990-01-01

83

SEMILOCAL AND ELECTROWEAK STRINGS  

Microsoft Academic Search

We review a class of non-topological defects in the standard electroweak model, and their implications. Starting with the semilocal string, which provides a counterexample to many well known properties of topological vortices, we discuss electroweak strings and their sta- bility with and without external influences such as magnetic fields. Other known properties of electroweak strings and monopoles are described in

Ana ACHUD CARRO; Tanmay VACHASPATI

84

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

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.

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

2012-01-01

85

Wiggly relativistic strings  

SciTech Connect

We derive the equations of motion for general strings, i.e. strings with arbitrary relation between tension {tau} and energy per unit length {epsilon}. The renormalization of {tau} and {epsilon} results from averaging out small scale wiggles on the string is obtained in the general case to lowest order in the amount of wiggliness. For Nambu-Goto strings we find deviations from the equation of state {epsilon}{tau} = constant in higher orders. Finally we show that under plausible assumptions wiggliness radically modifies the cosmic gauge string scenario.

Hong, Jooyoo; Kim, Jaewan; Sikivie, P.

1992-01-01

86

Wiggly relativistic strings  

SciTech Connect

We derive the equations of motion for general strings, i.e. strings with arbitrary relation between tension {tau} and energy per unit length {epsilon}. The renormalization of {tau} and {epsilon} results from averaging out small scale wiggles on the string is obtained in the general case to lowest order in the amount of wiggliness. For Nambu-Goto strings we find deviations from the equation of state {epsilon}{tau} = constant in higher orders. Finally we show that under plausible assumptions wiggliness radically modifies the cosmic gauge string scenario.

Hong, Jooyoo; Kim, Jaewan; Sikivie, P.

1992-07-01

87

Comparison of White Sucker Age Estimates from Scales, Pectoral Fin Rays, and Otoliths  

Microsoft Academic Search

The ages of 229 white suckers Catostomus commersonii from six drainages in the upper Missouri River basin were estimated from scales, pectoral fin ray sections, and lapilli otolith sections to evaluate the potential bias of age estimates between structures. Age estimates were compared by calculating the coefficient of variation, average percent error, percent agreement, and percent agreement within 1 year,

Ryan M. Sylvester; Charles R. Berry Jr

2006-01-01

88

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...

89

Segment Analysis of Sucker Brook: The Location of Sources of Pollution  

Microsoft Academic Search

Sucker Brook is located in the northwest portion of the Canandaigua Lake watershed, Ontario County, New York (Figs. 1 and 2). The relatively large watershed encompasses 6.9 square miles and flows into Canandaigua Lake at the City of Canandaigua. The Canandaigua Lake Watershed Task Force with the assistance of the Ontario County Planning Department and the Soil and Water Conservation

Joseph C. Makarewicz; Theodore W. Lewis; Stephen Lewandowski

1999-01-01

90

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

PubMed

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

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

2014-08-01

91

Preliminary Testing of the Role of Exercise and Predator Recognition for Bonytail and Razorback Sucker  

USGS Publications Warehouse

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.

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

2007-01-01

92

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

SciTech Connect

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.

Rdissi, A.

1984-01-01

93

Well production control system  

Microsoft Academic Search

An apparatus is described for monitoring the operation of a well pumping unit having a sucker-rod string and a power unit to reciprocate the rod string to produce fluid from an underground location, the apparatus having means for continuously compensating for a drift in characteristics of transducers used in monitoring the operation. The apparatus consists of: first transducer means for

R. S. Chandra; S. G. Quen; D. E. Eineicher; J. E. Lastra

1986-01-01

94

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

Federal Register 2010, 2011, 2012, 2013

...Sucker Creek Channel and Floodplain Restoration Project (Phase II), Rogue River...to examine impacts connected with restoration of approximately a 0.5 mile section...Proposed Action that includes a variety of restoration activities. Site-specific...

2010-02-02

95

Heterotic cosmic strings  

SciTech Connect

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

Becker, Katrin; Becker, Melanie; Krause, Axel [Radcliffe Institute, Harvard University, Cambridge, Massachusetts 02138 (United States) and Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, Texas 77843 (United States); Jefferson Physical Laboratory, Harvard University, Cambridge, Massachusetts 02138 (United States) and Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, Texas 77843 (United States)

2006-08-15

96

Covariant Closed String Coherent States  

SciTech Connect

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

Hindmarsh, Mark; Skliros, Dimitri [Department of Physics and Astronomy, University of Sussex, Brighton, East Sussex BN1 9QH (United Kingdom)

2011-02-25

97

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

USGS Publications Warehouse

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

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

2008-01-01

98

Rotating String Shapes  

NSDL National Science Digital Library

In this group activity, learners make multi-sided polygons with string. Learners slide a long piece of string through their fingers to make different kinds of triangles (isosceles, right, equilateral, and scalene) and quadrilaterals, including concave and convex shapes. Learners also draw the shapes from different points of view to explore congruency.

Exploratorium

2010-01-01

99

String Mediated Phase Transitions.  

National Technical Information Service (NTIS)

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 e...

E. Copeland D. Haws R. Rivers S. Holbraad

1988-01-01

100

Airplane on a String  

NSDL National Science Digital Library

Students analyze the motion of a toy airplane on a string using information from the video (a visible force scale, a frame-counter & an overlaid protractor). These measurments allow them to determine the mass and speed of the aircraft as well as the length of the string that constrains it.

Vonk, Matt

101

Axions in String Theory.  

National Technical Information Service (NTIS)

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 ...

P. Svrcek E. Witten

2006-01-01

102

Mechanisms of acid-base and ionoregulation in white suckers ( Catostomus commersoni ) in natural soft water  

Microsoft Academic Search

Simultaneous measurements of whole body proton flux and both unidirectional and net ion fluxes together with assessment of the blood acid-base, respiratory gas, electrolyte and lactate status were performed in white suckers (Catostomus commersoni) originating from a natural soft water lake ([Ca++]=0.18 meq·l?1) in Ontario, Canada. Fish were examined under control (pH? 6.8) and acidic conditions (pH?4.3) in natural soft

Helve Hõbe; Chris M. Wood; Brian R. McMahon

1984-01-01

103

Effective size, census size, and genetic monitoring of the endangered razorback sucker, Xyrauchen texanus  

Microsoft Academic Search

For the past several decades the Lake Mohave population of the federally endangered razorback sucker, Xyrauchen texanus, has had no natural recruitment because of intensive predation on larvae by non-native fishes. In response to impending extirpation,\\u000a a repatriation program was implemented where larval razorbacks are collected from the wild following natural spawning, reared\\u000a in protective custody, and then repatriated at

Thomas F. Turner; Thomas E. Dowling; Paul C. Marsh; Brian R. Kesner; Anne T. Kelsen

2007-01-01

104

Behavior and Passage Performance of Northern Pike, Walleyes, and White Suckers in an Experimental Raceway  

Microsoft Academic Search

The willingness and ability of wild adult northern pike Esox lucius, walleyes Sander vitreus, and white suckers Catostomus commersonii to ascend a 25- or 50-m experimental raceway against various water velocities (35–120 cm\\/s at 8 cm from the bottom) was measured. The probability that a fish of any given species would enter the raceway from its holding tank was significantly

Stephan J. Peake

2008-01-01

105

Effects of temperature, starvation and photoperiod on otolith increments in larval Chinese sucker, Myxocyprinus asiaticus  

Microsoft Academic Search

Effects of water temperature, starvation and photoperiod on otolith increment formation in larval Chinese sucker, Myxocyprinus asiaticus, were examined in this study. The results demonstrated that otolith increments of larvae reared under diel temperature fluctuations\\u000a were very clear and appeared with a high contrast, while those of larvae raised under constant water temperatures were vague\\u000a or hard to identify. The

Zhaobin Song; Zidong Fu; Chunlin He; Danzhou Shen; Bisong Yue

2009-01-01

106

Control rod drive  

DOEpatents

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.

Hawke, Basil C. (Solana Beach, CA)

1986-01-01

107

Lightning discharge protection rod  

NASA Technical Reports Server (NTRS)

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.

Bryan, Charles F., Jr. (inventor)

1987-01-01

108

Arto New String Calculator  

NSDL National Science Digital Library

Designed by a senior lecturer at the Department of Computer Science at the University of Helsinki in Finland, this website is a stand-alone Pascal program for string calculations. The idea came to him while visiting a French lute maker friend and the site has been continually updated since the original program was conceived. The calculator is useful only for calculating the tensions and diameters of strings made of homogenous material, thus wound strings, catlines and other such strings are excluded. The calculator is designed with lute instruments in mind but can be used for any stringed instrument: harpsichord, harp, guitar and pianos. The site provides easy to follow instructions and a glossary of the terms. Java 1.4 or 1.5 must be enabled to use this calculator.

Wikla, Arto

2006-10-04

109

Selenium in eggs and milt of razorback Sucker (Xyrauchen texanus) in the middle Green River, Utah.  

PubMed

Eggs from three female and milt from five male endangered razorback suckers (Xyrauchen texanus) were collected from the Razorback Bar (about 20 km upstream of Ashley Creek) in the Green River of northeastern Utah. Eggs, but not milt, had concentrations of selenium that were above the range of selenium concentrations in control fish from laboratory studies or reference fish from field studies. The concentrations, however, were below those reported in selenium-exposed fish that had reproductive problems in laboratory studies or field investigations. Tests with three streamside spawned pairs of razorback suckers, which were sampled for eggs and milt in this study, resulted in no hatching of fertilized eggs. Concentrations of selenium in eggs and milt were significantly correlated with selenium concentrations in muscle plugs taken from the same fish, but egg and milt concentrations were not significantly different from muscle plugs. Selenium concentrations in eggs of razorback suckers in the Green River may be sufficiently elevated to cause reproductive problems that are contributing to the decline of this species in the upper Colorado River Basin. PMID:8060163

Hamilton, S J; Waddell, B

1994-08-01

110

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

PubMed

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

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

2014-06-15

111

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

USGS Publications Warehouse

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.

Burdick, Summer M.; Rasmussen, Josh

2012-01-01

112

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

USGS Publications Warehouse

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.

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

2014-01-01

113

Stable string bit models  

NASA Astrophysics Data System (ADS)

In string bit models, the superstring emerges as a very long chain of "bits," in which s fermionic degrees of freedom contribute positively to the ground state energy in a way to exactly cancel the destabilizing negative contributions of d=s bosonic degrees of freedom. We propose that the physics of string formation be studied nonperturbatively in the class of string bit models in which s>d, so that a long chain is stable, in contrast to the marginally stable (s=d=8) superstring chain. We focus on the simplest of these models with s=1 and d=0, in which the string bits live in zero space dimensions. The string bit creation operators are N×N matrices. We choose a Hamiltonian such that the large N limit produces a string moving in one space dimension, with excitations corresponding to one Grassmann light-cone world sheet field (s=1) and no bosonic world sheet field (d=0). We study this model at finite N to assess the role of the large N limit in the emergence of the spatial dimension. Our results suggest that stringlike states with large bit number M may not exist for N?(M-1)/2. If this is correct, one can have finite chains of string bits, but not a continuous string, at finite N. Only for extremely large N can such chains behave approximately like a continuous string, in which case there will also be the (approximate) emergence of a new spatial dimension. In string bit models designed to produce a critical superstring at N=?, we can then expect only approximate Lorentz invariance at finite N, with violations of order 1/N2.

Sun, Songge; Thorn, Charles B.

2014-05-01

114

Piston rod seal  

DOEpatents

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.

Lindskoug, Stefan (Malmo, SE)

1984-01-01

115

Control rod cluster arrangement  

Microsoft Academic Search

This patent describes a nuclear reactor including nuclear core which is cooled and moderated by light water, the nuclear core comprising a plurality of parallel arranged openings therethrough and interspersed among the fuel assemblies. A control rod cluster arrangement comprises load follow control rod cluster assemblies with each load follow control rod cluster assembly being adapted to slidingly fit within

W. L. Orr; P. K. Doshi; C. M. Mildrum; T. R. Freeman

1987-01-01

116

Rod Ricochet Model.  

National Technical Information Service (NTIS)

A model to predict the ballistic ricochet of rod penetrators is presented. The model is based on the premise that the phenomenology of ricochet is one where the impacting rod feeds into a plastic hinge located at the rod/ target interface, and is thus div...

S. B. Segletes

2004-01-01

117

Cosmic Strings and the String Dilation.  

National Technical Information Service (NTIS)

In the paper the authors shall discuss another mechanism of dilaton production. Oscillating loops of cosmic string, which could be formed at a symmetry-breaking phase transition in the early universe, will copiously emit dilatons, as long as the character...

T. Damour A. Vilenkin

1996-01-01

118

Quantum null (super)strings  

Microsoft Academic Search

Null strings are the analog of massless particles, namely strings with zero tension or infinite slope. We present the supersymmetric extension of the null bosonic string constraint algebra and, in order to quantize covariantly, construct the corresponding BRST charge. We find that the null supersymmetric (bosonic) string is quantum consistent only in D = 10 (D = 26). The anomalies

J Gamboa-Rios; C. Ramírez; M. Ruiz-Altaba

1989-01-01

119

Multiple fuel rod gripper  

SciTech Connect

The multiple fuel rod gripper comprises a plurality of split tube collets arranged to be inserted into corresponding tapered holes in a locking plate. When the gripper has been positioned to have a plurality of fuel rods disposed in the holes of locking plate, an actuating mechanism causes the collets to be inserted into the tapered holes thereby causing the fuel rods to be inserted in the collets. The taper of the holes forces the collets into locking engagement with the fuel rods so that the fuel rods may be extracted from the fuel assembly.

Shields, E. P.

1985-11-05

120

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

NASA Astrophysics Data System (ADS)

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.

Dienes, Keith R.

2000-07-01

121

Concentric insulated tubing string  

SciTech Connect

An improved insulated tubing string with insulated coupling formed of concentric tubing members insulated from each other to prevent heat from the inner tubing from being conducted to and through the outer tubing. The coupling joins the outer tubing of successive tubing assemblies to provide additional strength to the string and the inner tubing is insulated within the coupling to prevent heat loss at the coupling. The inner tubing is elongated during fabrication and joined to the outer tubing when elongated to reduce heat stress on the string when in use.

Hutchison, S. O.

1984-10-16

122

Dark Energy from Strings  

NASA Astrophysics Data System (ADS)

A long-standing problem of theoretical physics is the exceptionally small value of the cosmological constant Lambda approx 10-120 measured in natural Planckian units. Here we derive this tiny number from a toroidal string cosmology based on closed strings. In this picture the dark energy arises from the correlation between momentum and winding modes that for short distances has an exponential fall-off with increasing values of the momenta. The freeze-out by the expansion of the background universe for these transplanckian modes may be interpreted as a frozen condensate of the closed-string modes in the three non-compactified spatial dimensions.

Frampton, Paul H.

2002-07-01

123

Cosmological cosmic strings  

NASA Technical Reports Server (NTRS)

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.

Gregory, Ruth

1988-01-01

124

Supermassive cosmic string compactifications  

NASA Astrophysics Data System (ADS)

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 Script 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.

Blanco-Pillado, Jose J.; Reina, Borja; Sousa, Kepa; Urrestilla, Jon

2014-06-01

125

Superconformal vortex strings  

NASA Astrophysics Data System (ADS)

We study the low-energy dynamics of semi-classical vortex strings living above Argyres-Douglas superconformal field theories. The worldsheet theory of the string is shown to be a deformation of the CPN model which flows in the infra-red to a superconformal minimal model. The scaling dimensions of chiral primary operators are determined and the dimensions of the associated relevant perturbations on the worldsheet and in the four dimensional bulk are found to agree. The vortex string thereby provides a map between the A-series of N=2 superconformal theories in two and four dimensions.

Tong, David

2006-12-01

126

Population biology and host-parasite relationships of Triganodistomum attenuatum (Trematoda: Lissorchiidae) infecting the white sucker, Catostomus commersoni (Lacépède).  

PubMed

Triganodistomum attenuatum demonstrated similar seasonal infection patterns in white suckers, Catostomus commersoni, from the Bellamy and Oyster rivers, New Hampshire. Mean intensity was highest in spring 1975 and 1976. Nongravid and gravid worms were common in the spring, and in the spring and summer, respectively. Most individuals of T. attenuatum parasitized the posterior portion of the sucker's intestine. No definite changes in prevalence and mean intensity were evident at either river as fish size increased. Male and female suckers had similar prevalences and mean intensities of infections. Although a significantly larger number of suckers from the Oyster River was infected than from the Bellamy River, the mean intensities were similar. Triganodistomum attenuatum was found to be host specific to the white sucker. Other fish species examined for the presence of T. attenuatum were as follow: creek chubsucker (Erimyzon oblongus), fallfish (Semotilus corporalis), golden shiner (Notemigonus crysoleucas), bridle shiner (Notropis bifrenatus), common shiner (N. cornutus), longnose dace (Rhinichthys cataractae), redfin pickerel (Esox americanus), pumpkinseed (Lepomis gibbosus), and swamp darter (Etheostoma fusiforme). The state of New Hampshire is a new locality record for T. attenuatum. PMID:7391871

Muzzall, P M

1980-04-01

127

Semiglobal Alice strings.  

National Technical Information Service (NTIS)

We show that in certain theories with topologically trivial quotient space of spontaneously broken gauge symmetry there can exist topologically stable strings that carry nonabelian gauge flux. These objects result from the ''accidental'' global degeneracy...

G. Dvali G. Senjanovic

1994-01-01

128

Strings at finite temperature  

SciTech Connect

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.

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

1985-12-15

129

Matrix string theory  

Microsoft Academic Search

Via compactification on a circle, the matrix mode] of M-theory proposed by Banks et a]. suggests a concrete identification between the large N limit of two-dimensional N = 8 supersymmetric Yang-Mills theory and type IIA string theory. In this paper we collect evidence that supports this identification. We explicitly identify the perturbative string states and their interactions, and describe the

Robbert Dijkgraaf; Erik Verlinde; Herman L Verlinde

1997-01-01

130

Use of Existing and Reconnected Backwater Habitats by Hatchery-Reared Adult Razorback Suckers: A Predictive Model for the Imperial Division, Lower Colorado River  

Microsoft Academic Search

Information regarding the life history and biological requirements and preferences for the razorback sucker Xyrauchen texanus is limited. Current recovery efforts involve rearing fish to juvenile or adult stages in hatcheries before they are released into areas of critical habitat that increase their survival. Our objectives were to develop a model based on habitat use by hatchery-reared razorback suckers in

Scott D. Gurtin; Joe E. Slaughter IV; Schuyler J. Sampson; Richard H. Bradford

2003-01-01

131

Spatial and temporal variation in abundance of Diplostomum spp. in walleye ( Stizostedion vitreum ) and white suckers ( Catostomus commersoni ) from the St. Lawrence River  

Microsoft Academic Search

Abundances of eye flukes (Diplostomum spp.) were compared between walleye (Stizostedion vitreum) and white suckers (Catostomus commersoni ) collected in late summer 1997 from Lake St. Louis and Lake St. Pierre, two expansions of the St. Lawrence River in Quebec, Canada. The white sucker, a benthic consumer, was more heavily in- fected than the walleye, a pelagic piscivore, in both

David J. Marcogliese; Pierre Dumont; Andrée D. Gendron; Yves Mailhot; Emmanuelle Bergeron; J. Daniel McLaughlin

2001-01-01

132

String-string duality conjecture in six dimensions and charged solitonic strings  

Microsoft Academic Search

It has recently been conjectured that the type IIA string theory compactified on K3 and the heterotic string theory compactified on a four dimensional torus describe identical string theories. The fundamental heterotic string can be regarded as a non-singular soliton solution of the type IIA string theory with a semi-infinite throat. We show that this solution admits 24 parameter non-singular

Ashoke Sen

1995-01-01

133

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

PubMed

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

Cabe, Patrick A

2011-10-01

134

Pull rod assembly  

DOEpatents

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.

Cioletti, O.C.

1988-04-21

135

Status of rod consolidation  

SciTech Connect

Two of the factors that need to be taken into account with rod consolidation are (1) the effects on rods from their removal from the fuel assembly and (2) the effects on rods as a result of the consolidation process. Potential components of both factors are described in the report. Discussed under (1) are scratches on the fuel rod surfaces, rod breakage, crud, extended burnup, and possible cladding embrittlement due to hydrogen injection at BWRs. Discussed under (2) are the increased water temperature (less than 10/sup 0/C) because of closer packing of the rods, formation of crevices between rods in the close-packed mode, contact with dissimilar metals, and the potential for rapid heating of fuel rods following the loss of water from a spent fuel storage pool. Another factor that plays an important role in rod consolidation is the cost of disposal of the nonfuel-bearing components of the fuel assembly. Also, the dose rate from the components - especially Inconel spacer grids - can affect the handling procedures. Several licensing issues that exist are described. A list of recommendations is provided. 98 refs., 5 figs., 5 tabs.

Bailey, W.J.

1985-04-01

136

Algal Toxins in Upper Klamath Lake, Oregon: Linking Water Quality to Juvenile Sucker Health  

USGS Publications Warehouse

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.

VanderKooi, S. P.; Burdick, S. M.; Echols, K. R.; Ottinger, C. A.; Rosen, B. H.; Wood, T. M.

2010-01-01

137

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

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

Burdick, Summer M.; Brown, Daniel T.

2010-01-01

138

Heterotic string corrections from the dual type II string  

Microsoft Academic Search

We introduce a method of using the a dual type-IIA string to compute ??-corrections to the moduli space of heterotic string compactifications. In particular we study the hypermultiplet moduli space of a heterotic string on a K3 surface. One application of this machinery shows that type-IIB strings compactified on a Calabi-Yau space suffer from worldsheet instantons, spacetime instantons and, in

Paul S. Aspinwall; M. Ronen Plesser

2000-01-01

139

Baby Skyrmion strings  

NASA Astrophysics Data System (ADS)

We consider two limiting cases of the 2+1 dimensional analog of the Skyrme model, where we show the existence of string-like solutions to the equations of motion. The model contains a conserved topological charge usually called the baryon number. Our strings are solitons which have a constant baryon number per unit length. In one limiting case, our configuration saturates a Bogomolnyi-type bound and is degenerate in energy per baryon with the baby Skyrmion which is the analog of the spherically symmetric Skyrmion soliton. Hence here the string is energetically stable. In the other limiting case these energies are still degenerate but neither saturates the corresponding Bogomolnyi-type bound. Here we find invariance under area preserving diffeomorphisms. Both cases are solvable analytically. For intermediate ranges of the parameters we provide numerical evidence of the existence of the string-like configurations in a region of the parameter space. We speculate that the string is classically stable here as the energy per length containing one baryon is less than the energy of an isolated baryon (radially symmetric “baby Skyrmion”).

Gisiger, T.; Paranjape, M. B.

1996-02-01

140

Gravity and Strings  

NASA Astrophysics Data System (ADS)

Preface; Part I. Introduction to Gravity and Supergravity: 1. Differential geometry; 2. Noether's theorems; 3. A perturbative introduction to general relativity; 4. Action principles for gravity; 5. N = 1, 2, d = 4 supergravities; 6. Conserved charges in general relativity; Part II. Gravitating Point-Particles: 7. The Schwarzschild black hole; 8. The Reissner-Nordström black hole; 9. The Taub-NUT solution; 10. Gravitational pp-waves; 11. The Kaluza-Klein black hole; 12. Dilaton and dilaton/axion black holes; 13. Unbroken supersymmetry; Part III. Gravitating Extended Objects of String Theory: 14. String theory; 15. The string effective action and T duality; 16. From eleven to four dimensions; 17. The type-IIB superstring and type-II T duality; 18. Extended objects; 19. The extended objects of string theory; 20. String black holes in four and five dimensions; Appendix A. Lie groups, symmetric spaces and Yang-Mills fields; Appendix B. Gamma matrices and spinors; Appendix C. n-Spheres; Appendix D. Palatini's identity; Appendix E. Conformal rescalings; Appendix F. Connections and curvature components; Appendix G. The harmonic operator on R3 x S1; References; Index.

Ortín, Tomás.

2004-03-01

141

Gravity and Strings  

NASA Astrophysics Data System (ADS)

Preface; Part I. Introduction to Gravity and Supergravity: 1. Differential geometry; 2. Noether's theorems; 3. A perturbative introduction to general relativity; 4. Action principles for gravity; 5. N = 1, 2, d = 4 supergravities; 6. Conserved charges in general relativity; Part II. Gravitating Point-Particles: 7. The Schwarzschild black hole; 8. The Reissner-Nordström black hole; 9. The Taub-NUT solution; 10. Gravitational pp-waves; 11. The Kaluza-Klein black hole; 12. Dilaton and dilaton/axion black holes; 13. Unbroken supersymmetry; Part III. Gravitating Extended Objects of String Theory: 14. String theory; 15. The string effective action and T duality; 16. From eleven to four dimensions; 17. The type-IIB superstring and type-II T duality; 18. Extended objects; 19. The extended objects of string theory; 20. String black holes in four and five dimensions; Appendix A. Lie groups, symmetric spaces and Yang-Mills fields; Appendix B. Gamma matrices and spinors; Appendix C. n-Spheres; Appendix D. Palatini's identity; Appendix E. Conformal rescalings; Appendix F. Connections and curvature components; Appendix G. The harmonic operator on R3 x S1; References; Index.

Ortín, Tomás.

2007-03-01

142

Effect of external electric fields on the phase behavior of colloidal silica rods.  

PubMed

We examine the effect of external electric fields on the behavior of colloidal silica rods. We find that the electric fields can be used to induce para-nematic and para-smectic phases, and to reduce the number of defects in smectic phases. At high field strengths, a new crystal structure was observed that consisted of strings of rods ordered in a hexagonal pattern in which neighboring rods were shifted along their length. We also present a simple model to describe this system, which we used in computer simulations to calculate the phase diagram for rods of L/D = 6, with L the end-to-end length of the rods and D the diameter of the rods. Our theoretical predictions for the phase behavior agree well with the experimental observations. PMID:25017809

Kuijk, Anke; Troppenz, Thomas; Filion, Laura; Imhof, Arnout; van Roij, René; Dijkstra, Marjolein; van Blaaderen, Alfons

2014-09-01

143

Foucault Rod Model  

NSDL National Science Digital Library

The Foucault Rod model displays the vibration of a circumnavigating rod. One end of the rod is firmly secured to a support. The free end of the rod has a weight attached, like the bob of a pendulum. The support of the rod is circumnavigating a central axis. The plane of swing of the Foucault rod is affected by the rotation in the same way as the Foucault pendulum is. The simulation shows simultaneously the motion with respect to the inertial coordinate system, and the motion as seen from a co-rotating point of view. For the co-rotating view there is a close-up view and an overview. You can examine and modify this simulation if you have EJS installed by right-clicking within the plot and selecting âOpen EJS Modelâ from the pop-up menu item. The Foucault Rod model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_nl_teunissen_foucault_rod.jar file will run the program if Java is installed. Additional information about this model can be found by visiting the authorâs web site: http://www.cleonis.nl/index.htm.

Teunissen, Cleon

2009-11-03

144

String Theory: Science or Philosophy?  

NSDL National Science Digital Library

This video segment from NOVA discusses the challenge of proving the scientific validity of string theory, in question because strings may be too small to ever be seen or detected, and therefore tested.

Foundation, Wgbh E.

2004-02-20

145

Quantum String Theory  

NASA Astrophysics Data System (ADS)

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.

Kawamoto, Noboru; Kugo, Taichiro

146

The confining trailing string  

NASA Astrophysics Data System (ADS)

We extend the holographic trailing string picture of a heavy quark to the case of a bulk geometry dual to a confining gauge theory. We compute the classical trailing confining string solution for a static as well as a uniformly moving quark. The trailing string is infinitely extended and approaches a confining horizon, situated at a critical value of the radial coordinate, along one of the space-time directions, breaking boundary rotational invariance. We compute the equations for the fluctuations around the classical solutions, which are used to obtain boundary force correlators controlling the Langevin dynamics of the quark. The imaginary part of the correlators has a non-trivial low-frequency limit, which gives rise to a viscous friction coefficient induced by the confining vacuum. The vacuum correlators are used to define finite-temperature dressed Langevin correlators with an appropriate high-frequency behavior.

Kiritsis, Elias; Mazzanti, Liuba; Nitti, Francesco

2014-02-01

147

Rod Photoreceptors Detect Rapid Flicker  

ERIC Educational Resources Information Center

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)

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

1977-01-01

148

Cosmic strings and galaxy formation  

NASA Technical Reports Server (NTRS)

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.

Bertschinger, Edmund

1989-01-01

149

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

USGS Publications Warehouse

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 ? 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.

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

2012-01-01

150

Probing the String Landscape  

ScienceCinema

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.

151

Probing the String Landscape  

ScienceCinema

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.

Keith Dienes

2010-01-08

152

Probing the String Landscape  

SciTech Connect

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.

Keith Dienes

2009-12-01

153

String Theory and Gauge Theories  

SciTech Connect

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.

Juan Maldacena

2009-02-20

154

New Connections Between String Theories  

Microsoft Academic Search

We consider the R-->0 limit of toroidal compactification in various string theories. This leads to new connections between seemingly different string theories: IIA and IIB, open and closed, oriented and unoriented. We also find two new extended objects which can couple consistently to strings: the Dirichlet-brane and the orientifold plane.

Jin Dai; R. G. Leigh; Joseph Polchinski

1989-01-01

155

String theory and quark confinement  

Microsoft Academic Search

This article is based on a talk given at the “Strings '97” conference. It discusses the search for the universality class of confining strings. The key ingredients include the loop equations, the zigzag symmetry, the non-linear renormalization group. Some new tests for the equivalence between gauge fields and strings are proposed.

Alexandre M. Polyakov

1998-01-01

156

Hazard Evaluation of Inorganics, Singly and in Mixtures, to Flannelmouth Sucker Catostomus latipinnisin the San Juan River, New Mexico  

Microsoft Academic Search

Larval flannelmouth sucker (Catostomus latipinnis) were exposed to arsenate, boron, copper, molybdenum, selenate, selenite, uranium, vanadium, and zinc singly, and to five mixtures of five to nine inorganics. The exposures were conducted in reconstituted water representative of the San Juan River near Shiprock, New Mexico. The mixtures simulated environmental ratios reported for sites along the San Juan River (San Juan

S. J. Hamilton; K. J. Buhl

1997-01-01

157

Effects of fertilizer, organic mulch and sucker hot water treatment on nematode populations and productivity of plantain  

Microsoft Academic Search

Objectives: To investigate the effects of fertilizer (F), organic mulch (Tithonia diversifolia) (M) and hot water treatment (H) on nematode population, growth and yield of plantain (Musa AAB, cv 'Agbagba'). Methodology and results: The study was conducted from 2003 to 2005 at the National Horticultural Research Institute, Ibadan, Nigeria. The treatments included: (1) mulching each sucker with 5.0 kg of

A. A. Kintomo; T. Ojurongbe; P. Y. K. Sallah; T. Ndabamenye

158

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

Federal Register 2010, 2011, 2012, 2013

...found in only a few lakes and reservoirs in...Klamath Basin and Lost River sub-basin in southern...Information Lost River and shortnose suckers...predominantly inhabit lake environments but...spend little time in rivers or streams after...passively to downstream lakes within a few...

2013-04-16

159

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

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.

Ellsworth, Craig M.; VanderKooi, Scott P.

2011-01-01

160

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

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 aver

Burdick, Summer M.

2012-01-01

161

Reionization from cosmic string loops  

SciTech Connect

Loops formed from a cosmic string network at early times would act as seeds for early formation of halos, which would form galaxies and lead to early reionization. With reasonable guesses about astrophysical and string parameters, the cosmic string scale G{mu} must be no more than about 3x10{sup -8} to avoid conflict with the reionization redshift found by WMAP. The bound is much stronger for superstring models with a small string reconnection probability. For values near the bound, cosmic string loops may explain the discrepancy between the WMAP value and theoretical expectations.

Olum, Ken D.; Vilenkin, Alexander [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155 (United States)

2006-09-15

162

Evolution of cosmic string networks  

NASA Technical Reports Server (NTRS)

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.

Albrecht, Andreas; Turok, Neil

1989-01-01

163

Evolution of cosmic string networks  

SciTech Connect

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.

Albrecht, A.; Turok, N.

1989-03-01

164

Current balancing for battery strings  

DOEpatents

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.

Galloway, James H. (New Baltimore, MI)

1985-01-01

165

Cosmic string loop microlensing  

NASA Astrophysics Data System (ADS)

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.

Bloomfield, Jolyon K.; Chernoff, David F.

2014-06-01

166

Wing on a String  

ERIC Educational Resources Information Center

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,…

Fitzgerald, Mike; Brand, Lance

2004-01-01

167

Antisymmetric string actions  

NASA Astrophysics Data System (ADS)

An action is presented for the free bosonic string on external flat space in terms of an antisymmetric second-rank string background tensor which is classically equivalent to the Nambu-Goto action. Both action and field equations are entirely described in terms of 2D world-sheet forms, without any reference to a 2D metric tensor background. The analysis of its canonical formulation shows how the quadratic Virasoro constraints are generated in this case and what their connection with the Bianchi identities are. Since in the orthonormal gauge the reduced action coincides with the standard one, it has the same critical dimension D = 26. The existence of an interaction term of a purely geometric structure stemming in the extrinsic curvature is pointed out. Its action and the new string field equations are then derived. This polynomial antisymmetric string action is uniformly generalized in order to describe d < D-dimensional extended objects in D-dimensional flat space. On leave of absence from Departamento de Física, Universidad Simon Bolívar, Apartado 80659, Caracas 1080A, Venezuela.

Aragone, C.

1986-12-01

168

Predictions from String Theory  

NASA Astrophysics Data System (ADS)

String theory is the leading candidate for an underlying theory of nature, as it provides a framework through which to address critical questions left unanswered by the Standard Model and Supersymmetry. A number of predictions of string constructions can be empirically tested at the Large Hadron Collider (LHC) and dark matter experiments. In this work I aim to make generic predictions of string theory, while combining bottom-up approaches to fill in the gaps in our understanding of string theory to make predictions for current and upcoming experiments. First I study moduli masses and claim that moduli dominated the energy density of the universe prior to big bang nucleosynthesis. We argue that in any string theory with stabilized moduli there will be at least one modulus field whose mass is of order the gravitino mass. Cosmology then generically requires the gravitino mass to be greater than 30 TeV and the early cosmological history of the Universe be non-thermal. We are then led to believe that the best-motivated channel for early LHC discovery is gluino pair-production events decaying into a high multiplicity of third generation quarks. We analyze signals and background at the LHC for 7 TeV center of mass energy for 1 fb -1 integrated luminosity, suggesting a reach for gluinos for masses about 650 GeV. Second, I seek to construct a Grand Unified Theory (GUT) within different branches of string theory. One promising GUT, developed outside of string theory, is Flipped-SU(5), which I show has serious phenomenological difficulties. I demonstrate both that Flipped-SU(5) requires an R-symmetry to solve the mu-problem, and that no R-symmetries exist in F-theory. Thus Flipped-SU(5) cannot serve as a GUT within F-theory. Similarly, I seek to construct a GUT within M-theory. My study is based upon the discrete symmetry proposed by Witten that forbids the mu-term and solves the doublet-triplet splitting problem, but does not address how the symmetry might be broken. I find that the symmetry must be broken by moduli stabilization. The inclusion of such symmetry-breaking yields a modified solution to the mu and doublet-triplet splitting problems, along with testable predictions regarding dark matter properties.

Kuflik, Eric

169

Control rod driveline and grapple  

DOEpatents

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.

Germer, John H. (San Jose, CA)

1987-01-01

170

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

USGS Publications Warehouse

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: 17?-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.

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

171

Nonlinearity and noise at the rod - rod bipolar cell synapse  

PubMed Central

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

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

2010-01-01

172

Device for balancing parallel strings  

DOEpatents

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.

Mashikian, Matthew S. (Storrs, CT) [Storrs, CT

1985-01-01

173

CGE Rod Amplifier Modules.  

National Technical Information Service (NTIS)

The performance and development history of the neodymium glass laser rod amplifiers in use at NRL on the Pharos II laser system is reviewed. The impact of possible future modifications is assessed. (Author)

J. M. McMahon

1978-01-01

174

Toxicity of selenium and other elements in food organisms to razorback sucker larvae.  

PubMed

Elevated selenium concentrations documented in water, sediment, and biota in irrigation drain water studies by U.S. Department of the Interior agencies and academia have raised concerns that selenium may be adversely affecting endangered fish in the upper Colorado River basin. The objective of the study was to determine the effects on endangered razorback sucker (Xyrauchen texanus) larvae from exposure to selenium and other trace elements in water and zooplankton collected from sites adjacent to the Colorado River near Grand Junction, CO. A 30-day study was initiated with 5-day-old larvae exposed in a 4 x 4 factor experiment with four food and four water treatments, and the biological endpoints measured were survival, growth, development, and whole-body residues of selenium. Mean selenium concentration in reference water (24-Road) was <0.7 microg/l, in reference food (brine shrimp) was 3.2 microg/g, at Horsethief was 1.6 microg/l in water and 6.0 microg/g in zooplankton, at Adobe Creek was 3.4 microg/l in water and 32 microg/g in zooplankton, and at Walter Walker was 13 microg/l in water and 52 microg/g in zooplankton. Although there were differences in concentrations of inorganic elements in water and biota among the three sites, selenium was apparently the only element elevated to concentrations of concern. Effects on survival were more prominent from dietary exposure compared to waterborne exposure. Selenium concentrations of >or=4.6 microg/g in food organisms adversely affected the survival of razorback sucker larvae. The onset of mortality in larvae exposed to food and water from Walter Walker seemed delayed compared to mortality in larvae exposed to food and water from Horsethief, which has been observed in two other studies. Elevated arsenic in one food source seemed to interact with selenium to reduce the toxic effects of selenium. PMID:12127741

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

2002-09-24

175

Correspondence of Z2-orbifold string and torus string  

NASA Astrophysics Data System (ADS)

We investigate the correspondence between a Z2 orbifold string and a torus string model which have the same vacuum amplitudes when they take particular radii. We show that ground states of the twisted sector of Z2 orbifold can be easily described by the torus string. In our formalism, we obtain the same amplitudes as those of Hamidi and Vafa, and of Dixon, Friedan, Martinec, and Shenker.

Kobayashi, K.

1987-06-01

176

New Supersymmetric String Compactifications  

SciTech Connect

We describe a new class of supersymmetric string compactifications to 4d Minkowski space. These solutions involve type II strings propagating on (orientifolds of) non Calabi-Yau spaces in the presence of background NS and RR fluxes. The simplest examples have descriptions as cosets, generalizing the three-dimensional nilmanifold. They can also be thought of as twisted tori. We derive a formula for the (super)potential governing the light fields, which is generated by the fluxes and certain ''twists'' in the geometry. Detailed consideration of an example also gives strong evidence that in some cases, these exotic geometries are related by smooth transitions to standard Calabi-Yau or G2 compactifications of M-theory.

Kachru, Shamit

2002-11-25

177

Axions in string theory  

NASA Astrophysics Data System (ADS)

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.

Svrcek, Peter; Witten, Edward

2006-06-01

178

New supersymmetric string compactifications  

NASA Astrophysics Data System (ADS)

We describe a new class of supersymmetric string compactifications to 4d Minkowski space. These solutions involve type II strings propagating on (orientifolds of) non Calabi-Yau spaces in the presence of background NS and RR fluxes. The simplest examples have descriptions as cosets, generalizing the three-dimensional nilmanifold. They can also be thought of as twisted tori. We derive a formula for the (super)potential governing the light fields, which is generated by the fluxes and certain ``twists'' in the geometry. Detailed consideration of an example also gives strong evidence that in some cases, these exotic geometries are related by smooth transitions to standard Calabi-Yau or G2 compactifications of M-theory.

Kachru, Shamit; Schulz, Michael B.; Tripathy, Prasanta K.; Trivedi, Sandip P.

2003-03-01

179

Axions in String Theory  

SciTech Connect

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.

Svrcek, Peter; /Stanford U., Phys. Dept. /SLAC; Witten, Edward; /Princeton, Inst. Advanced Study

2006-06-09

180

Little heterotic strings  

NASA Astrophysics Data System (ADS)

We discuss toroidal orbifolds of the E 8× E 8 heterotic string, in which the free-fermionic Higgs-matter splitting is implemented by a shift in the internal lattice coupled with the fermion numbers of the gauge degrees of freedom. We consider models in which some choices of the orbifold result in the projection of the graviton. In the models that we consider the projection also results in flipping the spin-statistics assignments in the massive string spectrum, whereas the massless spectrum retains the conventional spin-statistics assignments. We argue that the partition functions are mathematically consistent for one- and multi-loop amplitudes, owning to the existence of supersymmetry in the spectrum. A duality between different models at non-zero temperature is briefly discussed.

Faraggi, Alon E.; Manno, Elisa

2010-04-01

181

Movement of Sacramento Sucker, Catostomus occidentalis , and Hitch, Lavinia exilicauda , during a Spring Release of Water from Camanche Dam in the Mokelumne River, California  

Microsoft Academic Search

Synopsis  We recorded the movement of Sacramento suckers, Catostomus occidentalis, and hitch, Lavinia exilicauda, before and during a controlled flood release on a regulated California Central Valley River, using radio telemetry. Both\\u000a species made small, local movements (<550 m) during pre-flood flows. During flood releases, some individual suckers made significantly\\u000a larger movements (>8100 m) both up and downstream of pre-flood flow locations within

Carson A. Jeffres; A. Peter Klimley; Joseph E. Merz; Joseph J. Cech Jr

2006-01-01

182

Transposition invariant string matching  

Microsoft Academic Search

Given strings A = a1a2 ...a m and B = b1b2 ...b n over an alphabet ? ? U ,w hereU is some numerical universe closed under addition and subtraction, and a distance function d(A,B) that gives the score of the best (partial) matching of A and B ,t hetransposition invariant distance is mint?U{d(A + t,B) } ,w hereA +

Veli Mäkinen; Gonzalo Navarro; Esko Ukkonen

2005-01-01

183

Anyons from strings.  

PubMed

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

Mezincescu, Luca; Townsend, Paul K

2010-11-01

184

Comparing double string theory actions  

NASA Astrophysics Data System (ADS)

Aimed to a deeper comprehension of a manifestly T-dual invariant formulation of string theory, in this paper a detailed comparison between the non-covariant action proposed by Tseytlin and the covariant one proposed by Hull is done. These are obtained by making both the string coordinates and their duals explicitly appear, on the same footing, in the world-sheet action, so "doubling" the string coordinates along the compact dimensions. After a discussion on the nature of the constraints in both the models and the relative quantization, it results that the string coordinates and their duals behave like "non-commuting" phase space coordinates but their expressions in terms of Fourier modes generate the oscillator algebra of the standard bosonic string. A proof of the equivalence of the two formulations is given. Furthermore, open-string solutions are also discussed.

De Angelis, L.; Gionti S. J, G.; Marotta, R.; Pezzella, F.

2014-04-01

185

Classical string in curved backgrounds  

SciTech Connect

The Mathisson-Papapetrou method is originally used for derivation of the particle world line equation from the covariant conservation of its stress-energy tensor. We generalize this method to extended objects, such as a string. Without specifying the type of matter the string is made of, we obtain both the equations of motion and boundary conditions of the string. The world sheet equations turn out to be more general than the familiar minimal surface equations. In particular, they depend on the internal structure of the string. The relevant cases are classified by examining canonical forms of the effective 2-dimensional stress-energy tensor. The case of homogeneously distributed matter with the tension that equals its mass density is shown to define the familiar Nambu-Goto dynamics. The other three cases include physically relevant massive and massless strings, and unphysical tachyonic strings.

Vasilic, Milovan; Vojinovic, Marko [Institute of Physics, P. O. Box 57, 11001 Belgrade (Serbia and Montenegro)

2006-06-15

186

Dynamics of strings between walls  

SciTech Connect

Configurations of vortex-strings stretched between or ending on domain walls were previously found to be 1/4 BPS states. Among zero modes of string positions, the center of mass of strings in each region between two adjacent domain walls is shown to be non-normalizable whereas the rests are normalizable. We study dynamics of vortex-strings stretched between separated domain walls by using two methods, the moduli space (geodesic) approximation of full 1/4 BPS states and the charged particle approximation for string endpoints in the wall effective action. In the first method we obtain the effective Lagrangian explicitly and find the 90 degree scattering for head-on collision. In the second method the domain wall effective action is assumed to be U(1){sup N} gauge theory, and we find a good agreement between two methods for well separated strings. This talk is based on the work [1].

Eto, Minoru [INFN, Sezione di Pisa, Largo Pontecorvo, 3, Ed. C, 56127 Pisa (Italy); Fujimori, Toshiaki; Nagashima, Takayuki [Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Nitta, Muneto [Department of Physics, Keio University, Hiyoshi, Yokohama, Kanagawa 223-8521 (Japan); Ohashi, Keisuke [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, CB3 0WA (United Kingdom); Sakai, Norisuke [Department of Mathematics, Tokyo Woman's Christian University, Tokyo 167-8585 (Japan)

2008-11-23

187

Cosmic string induced CMB maps  

SciTech Connect

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

Landriau, M. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Shellard, E. P. S. [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

2011-02-15

188

Classical theory of radiating strings  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

189

Evolution of cosmic string networks  

NASA Technical Reports Server (NTRS)

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.

Albrecht, Andreas; Turok, Neil

1989-01-01

190

The Effective Theory of Strings  

NASA Astrophysics Data System (ADS)

We show that the Nambu-Goto string, and its higher dimensional generalizations, can be quantized, in the sense of an effective theory, in any dimension of the target space. The crucial point is to consider expansions around classical string configurations. We are using tools from perturbative algebraic quantum field theory, quantum field theory on curved spacetimes, and the Batalin-Vilkovisky formalism. Our model has some similarities with the Lüscher-Weisz string, but we allow for arbitrary classical background string configurations and keep the diffeomorphism invariance.

Bahns, Dorothea; Rejzner, Katarzyna; Zahn, Jochen

2014-05-01

191

General Relativity Invariance and String Field Theory.  

National Technical Information Service (NTIS)

The general covariance principle in the string field theory is considered. The algebraic properties of the string Lie derivative are discussed. The string vielbein and spin connection are introduced and an action invariant under general co-ordinate transf...

I. Y. Aref'eva I. V. Volovich

1987-01-01

192

Optimum fuel rod dimensions  

SciTech Connect

ABB Combustion Engineering (ABB CE) evaluated two fuel rod designs with different moderator-to-fuel ratios: (1) a standard ABB CE rod for 16 X 16 fuel with high uranium loading: value-added pellets, and (2) a thinner rod with reduced clad surface area, clad thickness, and uranium loading: here called the 16 X 16 OFA (optimized fuel assembly). It is well known that all pressurized water reactors are under-moderated; this ensures a negative moderator temperature coefficient (MTC). Increasing the lattice moderation is thus expected to improve uranium utilization while having a detrimental effect on MTC. This study was performed to quantify the uranium utilization benefit and other effects of increased moderation.

Jonsson, A.; Gavin, P.H.; Terney, W.B.; Dixon, D.J. [ABB Combustion Engineering Nuclear Power, Inc., Windsor, CT (United States)

1997-12-01

193

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

USGS Publications Warehouse

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.

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

2003-01-01

194

Conformal Supergravity in Twistor-String Theory  

Microsoft Academic Search

Conformal supergravity arises in presently known formulations of twistor-string theory either via closed strings or via gauge-singlet open strings. We explore this sector of twistor-string theory, relating the relevant string modes to the particles and fields of conformal supergravity. We use the twistor-string theory to compute some tree level scattering amplitudes with supergravitons. Since the supergravitons interact with the same

Nathan Berkovits; Edward Witten

2004-01-01

195

Field theory of the interacting string: The closed string  

Microsoft Academic Search

We recast dual models in the language of a quantum field theory of functional fields, restricting ourselves for simplicity to the closed string model. We derive the dynamics for both scalar and spinor functional fields from a unique parametrization invariant action. Passages to the Hamiltonian formalism and second quantization are explicitly worked out for the closed mesonic string in the

Charles Marshall; P. Ramond

1975-01-01

196

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

USGS Publications Warehouse

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.

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

2006-01-01

197

Survival Rates and Movement of Hatchery-Reared Razorback Suckers in the Upper Colorado River Basin, Utah and Colorado  

Microsoft Academic Search

We used tag–recapture data to estimate apparent survival and capture probability for 119,129 hatchery-reared, federally endangered razorback suckers Xyrauchen texanus stocked into upper Colorado River basin streams during 1995–2005. Effects investigated included reach, year, and season of stocking; fish total length (TL) at time of stocking; survival in the first year after stocking versus in subsequent years; and sampling effort.

Koreen A. Zelasko; Kevin R. Bestgen; Gary C. White

2010-01-01

198

Growth chronologies of white sucker, Catostomus commersoni , and lake trout, Salvelinus namaycush : a comparison among lakes and between trophic levels  

Microsoft Academic Search

A growth chronology index was used to determine whether changes in ecosystem structure and function in lakes could be associated\\u000a with fish growth histories. Growth chronologies were compared for white suckers, Catostomus commersoni, from Little Moose (oligotrophic), Oneida (eutrophic), and Cayuga (mesotrophic) lakes (New York) from opercular bone growth\\u000a increments, and for lake trout, Salvelinus namaycush, from Little Moose Lake

Nathan G. Smith; Charles C. Krueger; John M. Casselman

2008-01-01

199

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

USGS Publications Warehouse

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.

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

2006-01-01

200

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

USGS Publications Warehouse

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.

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

2010-01-01

201

Sequestering in String Theory  

SciTech Connect

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.

Kachru, Shamit; McAllister, Liam; Sundrum, Raman

2007-04-04

202

Nucleus from string theory  

NASA Astrophysics Data System (ADS)

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.

Hashimoto, Koji; Morita, Takeshi

2011-08-01

203

Rod Pinch Diode.  

National Technical Information Service (NTIS)

This patent discloses an improved diode for forming an intense electron beam and propagating the beam. The diode includes a cathode having a bore, and a rod-shaped anode having a medial tapered section which extends, approximately coaxially, through the b...

R. A. Mahaffey S. A. Goldstein J. Golden G. Cooperstein

1980-01-01

204

Rod Pinch Diode.  

National Technical Information Service (NTIS)

An improved diode, for forming an intense electron beam and propagating the beam, is described. The diode includes a cathode having a bore, and a rod-shaped anode having a medial tapered section which extends, approximately coaxially, through the bore of ...

R. A. Mahaffey

1978-01-01

205

Domain Walls with Strings Attached.  

National Technical Information Service (NTIS)

We have constructed a bulk & brane action of IIA theory which describes a pair of BPS domain walls on S1/Z2, with strings attached. The walls are given by two orientifold O8-planes with coincident D8-branes and 'F10D0'-strings are stretched between the wa...

M. Shmakova

2001-01-01

206

String theory on group manifolds  

Microsoft Academic Search

A number of issues concerning affine Lie algebras and string propagation on group manifolds are addressed. We show that a 1 + 1 dimensional quantum field theory which gives a realization of current algebra (for any non-abelian Lie group G) will always give rise to an ``integrable'' representation. It is known that string propagation on the group manifold can give

Doron Gepner; Edward Witten

1986-01-01

207

Small instantons in string theory  

Microsoft Academic Search

A long-standing puzzle about the heterotic string has been what happens when an instanton shrinks to zero size. It is argued here that the answer at the quantum level is that an extra SU(2) gauge symmetry appears that is supported in the core of the instanton. Thus in particular the quantum heterotic string has vacua with higher rank than is

Edward Witten

1996-01-01

208

Towards inflation in string theory  

Microsoft Academic Search

We investigate the embedding of brane inflation into stable compactifications of string theory. At first sight a warped compactification geometry seems to produce a naturally flat inflaton potential, evading one well known difficulty of brane antibrane scenarios. Careful consideration of the closed string moduli reveals a further obstacle: superpotential stabilization of the compactification volume typically modifies the inflaton potential and

Shamit Kachru; Renata Kallosh; Andrei Linde; Juan Maldacena; Liam McAllister; Sandip P. Trivedi

2003-01-01

209

String theory and noncommutative geometry  

Microsoft Academic Search

We extend earlier ideas about the appearance of noncommutative geometry in string theory with a nonzero B-field. We identify a limit in which the entire string dynamics is described by a minimally coupled (supersymmetric) gauge theory on a noncommutative space, and discuss the corrections away from this limit. Our analysis leads us to an equivalence between ordinary gauge fields and

Nathan Seiberg; Edward Witten

1999-01-01

210

Geometry, Topology and String Theory.  

National Technical Information Service (NTIS)

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 problems of a given classical space-time se...

U. Varadarajan

2003-01-01

211

Fast Pattern Matching in Strings  

Microsoft Academic Search

An algorithm is presented which finds all occurrences of one. given string within another, in running time proportional to the sum of the lengths of the strings. The constant of proportionality is low enough to make this algorithm of practical use, and the procedure can also be extended to deal with some more general pattern-matching problems.A theoretical application of the

Donald E. Knuth; Vaughan R. Pratt

1977-01-01

212

Energy in a String Wave  

ERIC Educational Resources Information Center

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…

Ng, Chiu-king

2010-01-01

213

A Platonic Sextet for Strings  

ERIC Educational Resources Information Center

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.

Schaffer, Karl

2012-01-01

214

Experimenting with String Musical Instruments  

ERIC Educational Resources Information Center

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…

LoPresto, Michael C.

2012-01-01

215

Summing Planar Bosonic Open Strings  

SciTech Connect

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.

Bardakci, Korkut

2006-02-16

216

Testing strings at the LHC  

NASA Astrophysics Data System (ADS)

I discuss the main motivations and directions for physics beyond the Standard Model of elementary particles and I give a short introduction on string theory. This theory introduces a new physical constant, the string length, under which a new fundamental structure appears, changing drastically the laws of nature. In particular, lowering the string scale in the Te V region provides a theoretical framework for solving the so-called mass hierarchy problem: the apparent weakness of gravity can be accounted by the existence of large internal dimensions, in the submillimeter region, and transverse to a braneworld where our observed universe is confined. In these lectures, I describe the main properties of string phenomenology with high or low string scale. In the latter case, I discuss also its implications for new gravitational phenomena that can be observed at both particle colliders, and in non-accelerator experiments searching for new short range forces.

Antoniadis, I.

2013-07-01

217

Subcritical string and large N QCD  

SciTech Connect

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.

Thorn, Charles B. [Institute for Fundamental Theory, Department of Physics, University of Florida, Gainesville Florida 32611 (United States)

2008-10-15

218

String Mining in Bioinformatics  

NASA Astrophysics Data System (ADS)

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].

Abouelhoda, Mohamed; Ghanem, Moustafa

219

String Mining in Bioinformatics  

NASA Astrophysics Data System (ADS)

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].

Abouelhoda, Mohamed; Ghanem, Moustafa

220

Cosmic string wakes  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

221

Vortices in vibrated granular rods  

NASA Astrophysics Data System (ADS)

We report the experimental observation of vortex patterns in vertically vibrated granular rods. Above a critical packing fraction, moving ordered domains of nearly vertical rods spontaneously form and coexist with horizontal rods. The domains of vertical rods coarsen in time to form large vortices. We investigate the conditions under which the vortices occur by varying the number of rods, vibration amplitude, and frequency. The size of the vortices increases with the number of rods. We characterize the growth of the ordered domains by measuring the area fraction of the ordered regions as a function of time. A void-filling model is presented to describe the nucleation and growth of the vertical domains. We track the ends of the vertical rods and obtain the velocity fields of the vortices. The rotation speed of the rods is observed to depend on the vibration velocity of the container and on the packing. To investigate the impact of the direction of driving on the observed phenomena, we performed experiments with the container vibrated horizontally. Although vertical domains form, vortices are not observed. We therefore argue that the motion is generated due to the interaction of the inclination of the rods with the bottom of a vertically vibrated container. We also perform simple experiments with a single row of rods in an annulus. These experiments directly demonstrate that the rod motion is generated when the rods are inclined from the vertical, and is always in the direction of the inclination.

Blair, Daniel L.; Neicu, T.; Kudrolli, A.

2003-03-01

222

Control rod calibration including the rod coupling effect  

SciTech Connect

In a reactor containing more than one control rod, which includes all reactors licensed in the United States, there will be a 'coupling' or 'shadowing' of control rod flux at the location of a control rod as a result of the flux depression caused by another control rod. It was decided to investigate this phenomenon further, and eventually to put calibration table data or formulae in a small computer in the control room, so once could insert the positions of the three control rods and receive the excess reactivity without referring to separate tables. For this to be accomplished, a 'three control- rod reactivity function' would be used which would include the flux coupling between the rods. The function is design and measured data was fitted into it to determine the calibration constants. The input data for fitting the trial functions consisted of 254 data points, each consisting of the position of the reg, shim, and transient rods, and the total excess reactivity. (About 200 of these points were 'critical balance points', that is the rod positions for which reactor was critical, and the remainder were determined by positive period measurements.) Although this may be unrealistic from a physical viewpoint, the function derived gave a very accurate recalculation of the input data, and thus would faithfully give the excess reactivity for any possible combination of the locations of the three control rods. The next step, incorporation of the three-rod function into the minicomputer, will be pursued in the summer and fall of 1984.

Szilard, R.; Nelson, G.W. [University of Arizona, Tucson, AZ (United States)

1984-07-01

223

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

USGS Publications Warehouse

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.

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

2009-01-01

224

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

PubMed

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

Jordan, Alexander H; Monin, Benoît

2008-08-01

225

Dynamical evolution of cosmic strings  

SciTech Connect

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

Bouchet, F.R.

1988-05-11

226

Removable drill string stabilizers  

SciTech Connect

A stabilizer sleeve, or other sleeve, to be releasably mounted on a drill collar for centering a drill string in a well bore, includes an outer stabilizer sleeve to be mounted on the cylindrical periphery of the drill collar and having an internally threaded bore, the threads of which have conical roots , receiving an externally threaded yieldable sleeve member placed over the drill collar, the crests of the external threads also being conical, rotation of the yieldable member threading it into the stabilizer sleeve and effecting its contraction until its internal surface contacts the periphery of the drill collar, further rotation and tightening of the sleeve member in the stabilizer sleeve compressing the sleeve member against the drill collar periphery, with the crests bearing against the root portions of the internal sleeve threads to secure the sleeve frictionally in position on the drill collar.

Manuel, T.

1981-01-20

227

Wormholes in string theory  

SciTech Connect

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.

Lyons, A. (Theoretical Physics Institute, Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1 (Canada)); Hawking, S.W. (Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW (UK))

1991-12-15

228

Supersymmetric string waves  

SciTech Connect

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.

Bergshoeff, E.A. (Institute for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)); Kallosh, R.; Ortin, T. (Physics Department, Stanford University, Stanford, California 94305 (United States))

1993-06-15

229

Boosted black string bombs  

NASA Astrophysics Data System (ADS)

We study the formation of superradiant bound states for massive scalar fields in five-dimensional rotating black string geometries with a non-vanishing Kaluza-Klein momentum along the compact direction. Even though all Kaluza-Klein modes may form bound states in this geometry, in realistic extra-dimensional models and astrophysical black holes only the zero-mode is sufficiently light for superradiant instabilities to develop, provided the field has a small but non-vanishing mass, as for example for axion-like particles. We use analytical and numerical methods to show that, although the Kaluza-Klein momentum decreases the upper bound on the field mass for an instability to develop, it may enhance its maximum growth rate by more than 50%, thus boosting the black hole bomb mechanism. We discuss the possible observational consequences of this result and its potential as an astrophysical probe of non-trivial extra-dimensional compactifications.

Rosa, João G.

2013-02-01

230

Annular burnable absorber rod  

SciTech Connect

This patent describes a neutron irradiation environment of a water cooled and moderated reactor core a fuel assembly having a discrete annular burnable absorber rod, the rod being free of nuclear fuel material the rod comprising a first elongated hollow tube having opposed ends, a second elongated hollow tube having opposed ends. The first and second tubes are constructed of a zirconium material, the first and second tubes concentrically arranged about a common axis to provide a coextensive annular space therebetween and a path for the water through the first tube along the common axis. A sealing means seals the annular space at common opposed ends of the first and second tube and a hollow niobium tubular support is arranged within the annular space. The tubular support has an inner and outer surface, a layer of burnable neutron absorber material provided on at least a portion of one of the surfaces of the support the layer of the burnable neutron absorber material selected from the group of boron compounds consisting of boron carbide, boron nitride and zirconium diboride; and the layer of the burnable neutron absorber material having a thickness between 0.002 to 0.010 inches.

Chubb, W.

1986-12-02

231

Safety rod latch inspection  

SciTech Connect

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.

Leader, D.R.

1992-02-01

232

Safety rod latch inspection  

SciTech Connect

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.

Leader, D.R.

1992-02-01

233

Homotopy Classification of Bosonic String Field Theory  

NASA Astrophysics Data System (ADS)

We prove the decomposition theorem for the loop homotopy Lie algebra of quantum closed string field theory and use it to show that closed string field theory is unique up to gauge transformations on a given string background and given S-matrix. For the theory of open and closed strings we use results in open-closed homotopy algebra to show that the space of inequivalent open string field theories is isomorphic to the space of classical closed string backgrounds. As a further application of the open-closed homotopy algebra, we show that string field theory is background independent and locally unique in a very precise sense. Finally, we discuss topological string theory in the framework of homotopy algebras and find a generalized correspondence between closed strings and open string field theories.

Münster, Korbinian; Sachs, Ivo

2014-05-01

234

Concentric steaming string downhole apparatus  

SciTech Connect

A downhole concentric tubing string is disclosed for use in distributing steam, or other hot fluid to separated subsurface formations along a well bore. The apparatus includes elements for deflecting the steam from one string into the annulus of a cased well for injection through openings into the formation, elements for conducting the steam in another of the concentric string to a second set of openings for injection into another portion of the formation, and elements for isolating and separating the two separate injection intervals.

Anderson, G.W.; Hutchison, S.O.

1983-08-23

235

Finite momentum at string endpoints  

NASA Astrophysics Data System (ADS)

We argue that classical strings, both bosonic and supersymmetric, can have finite energy and momentum at their endpoints. We show that in a general curved background, string endpoints must propagate along null geodesics as long as their energy remains finite. Finite endpoint momentum allows strings with a fixed energy to travel a greater distance in a five-dimensional anti-de Sitter Schwarzschild background than has been possible for classical solutions considered previously. We review the relevance to heavy ion phenomenology of the dependence of this distance on energy, and we propose a scheme for determining the instantaneous rate of energy loss.

Ficnar, Andrej; Gubser, Steven S.

2014-01-01

236

Yangian in the twistor string  

NASA Astrophysics Data System (ADS)

We study symmetries of the quantized open twistor string. In addition to global PSL(4|4) symmetry, we find non-local conserved currents. The associated non-local charges lead to Ward identities which show that these charges annihilate the string gluon tree amplitudes, and have the same form as symmetries of amplitudes in mathcal{N} = 4 super conformal Yang Mills theory. We describe how states of the open twistor string form a realization of the PSL(4|4) Yangian superalgebra.

Corn, John; Creutzig, Thomas; Dolan, Louise

2010-10-01

237

Radio bursts from superconducting strings  

NASA Astrophysics Data System (ADS)

We show that radio bursts from cusps on superconducting strings are linearly polarized, thus providing a signature that can be used to distinguish them from astrophysical sources. We write the event rate of string-generated radio transients in terms of observational variables, namely, the event duration and flux. Assuming a canonical set of observational parameters, we find that the burst event rate can be quite reasonable, e.g., order ten a year for grand unified strings with 100 TeV currents, and a lack of observed radio bursts can potentially place strong constraints on particle physics models.

Cai, Yi-Fu; Sabancilar, Eray; Vachaspati, Tanmay

2012-01-01

238

From strings to the MSSM  

NASA Astrophysics Data System (ADS)

We review recent progress in embedding the supersymmetric standard model into string theory. We discuss how, with the incorporation of certain aspects of grand unification, a search strategy can be developed that allows one to efficiently find rather large numbers of promising string vacua. Global string-derived models with the following features are discussed: (i) exact MSSM spectrum below the unification scale; (ii) R-parity; (iii) hierarchical Yukawa couplings with non-trivial mixing; (iv) solution to the ? problem; (v) see-saw suppressed neutrino masses.

Nilles, Hans Peter; Ramos-Sánchez, Saúl; Ratz, Michael; Vaudrevange, Patrick K. S.

2009-01-01

239

Closed string amplitudes as single-valued open string amplitudes  

NASA Astrophysics Data System (ADS)

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

Stieberger, Stephan; Taylor, Tomasz R.

2014-04-01

240

Perturbations from strings don't look like strings!  

NASA Technical Reports Server (NTRS)

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.

Albrecht, Andreas; Stebbins, Albert

1991-01-01

241

Perturbations from strings don't look like strings  

SciTech Connect

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.

Albrecht, A.; Stebbins, A.

1991-08-01

242

Fundamental strings in open string theory at the tachyonic vacuum  

Microsoft Academic Search

We show that the world-volume theory on a D-p-brane at the tachyonic vacuum has solitonic string solutions whose dynamics is governed by the Nambu-Goto action of a string moving in (25+1) dimensional space-time. This provides strong evidence for the conjecture that at this vacuum the full (25+1) dimensional Poincaré invariance is restored. We also use this result to argue that

Ashoke Sen

2001-01-01

243

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

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.

Burdick, Summer M.; Hewitt, David A.

2012-01-01

244

A Hierarchy of Super w Strings  

Microsoft Academic Search

It is shown that the N-extended super wn string can be obtained as a special class of vacua of both the N-extended super wn+1 string and the (N + 1)-extended super wn string. This hierarchy of super w string theories includes as subhierarchies both the superstring hierarchy given by Bastianelli, Ohta and Petersen and the w string hierarchy given by

Hiroshi Kunitomo; Makoto Sakaguchi; Akira Tokura

1994-01-01

245

Charting the landscape of supercritical string theory.  

PubMed

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. PMID:17995316

Hellerman, Simeon; Swanson, Ian

2007-10-26

246

Charting the Landscape of Supercritical String Theory  

SciTech Connect

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.

Hellerman, Simeon; Swanson, Ian [School of Natural Sciences, Institute for Advanced Study Princeton, New Jersey 08540 (United States)

2007-10-26

247

Cosmic string catalysis of skyrmion decay  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

248

Closest Strings, Primer Design, and Motif Search  

Microsoft Academic Search

IntroductionCLOSEST STRINGGiven: k strings from #and a positive integer d.Question: Find a "closest string" s such that none ofthe given strings has Hamming distance greater than dto s.Example (dHdenotes the Hamming distance):TAGTGTATTTGTTGTATTTAGTGTGCTs =TGGTGTGTT"closest string" withdH(s, s i )2 for i = 1, 2, 3, 4.CLOSEST STRING is NP-complete.Here, we exploit two new techniques for solving CLOSESTSTRING (partially presented in [4])

Jens Gramm; Falk Hüffner; Rolf Niedermeier

2002-01-01

249

Tachyon Dynamics in Open String Theory1  

Microsoft Academic Search

In this review we describe our current understanding of the properties of open string tachyons on an unstable D-brane or brane-antibrane system in string theory. The various string theoretic methods used for this study include techniques of two dimensional confor- mal field theory, open string field theory, boundary string field theory, non-commutative solitons etc. We also describe various attempts to

Ashoke Sen

2004-01-01

250

Tachyon Dynamics in Open String Theory  

Microsoft Academic Search

In this review we describe our current understanding of the properties of open string tachyons on an unstable D-brane or brane-antibrane system in string theory. The various string theoretic methods used for this study include techniques of two-dimensional conformal field theory, open string field theory, boundary string field theory, noncommutative solitons, etc. We also describe various attempts to understand these

Ashoke Sen

2005-01-01

251

Spin chains and string theory.  

PubMed

Recently, an important test of the anti de Sitter/conformal field theory correspondence has been done using rotating strings with two angular momenta. We show that such a test can be described more generally as the agreement between two actions: one a low energy description of a spin chain appearing in the field theory side, and the other a limit of the string action in AdS5xS5. This gives a map between the mean value of the spin in the boundary theory and the position of the string in the bulk, and shows how a string action can emerge from a gauge theory in the large-N limit. PMID:15524978

Kruczenski, Martin

2004-10-15

252

Wave Propagation on a String  

NSDL National Science Digital Library

An animated example of wave propagation on a string composed of two segments of different densities and velocities. Fortran and Unix/GMT source code used to make the animation are available for download from the same site.

253

Cosmological Aspects of String Compactifications  

SciTech Connect

The organization of this work is as follows. In Chapters 2, 3, and 4 they discuss the dynamics of unfixed moduli in quantum field theory and in string theory, with emphasis on applications to cosmological model-building. Moduli-stabilizing effects are not included, because the goal is to understand the evolution of moduli whose potentials remain approximately flat. In Chapter 5 they develop a technique for stabilizing moduli in the heterotic string, and they construct the first stabilized, weakly-coupled heterotic vacua. In Chapter 6 they utilize advances in the stabilization of type IIB compactifications to build the first models of inflation in stabilized string vacua. Finally, in Chapter 7 they examine the effects of volume-stabilization on the inflaton mass in closely-related scenarios of string inflation.

McAllister, Liam Patrick; /Stanford U., Phys. Dept. /SLAC

2006-03-10

254

Nuclear Force from String Theory  

NASA Astrophysics Data System (ADS)

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

Hashimoto, Koji

2010-04-01

255

Yangian in the twistor string  

Microsoft Academic Search

We study symmetries of the quantized open twistor string. In addition to global PSL(4|4) symmetry, we find non-local conserved\\u000a currents. The associated non-local charges lead to Ward identities which show that these charges annihilate the string gluon\\u000a tree amplitudes, and have the same form as symmetries of amplitudes in $$ \\\\mathcal{N} = 4 $$ super conformal Yang Mills theory. We

John Corn; Thomas Creutzig; Louise Dolan

2010-01-01

256

Strings and branes are waves  

NASA Astrophysics Data System (ADS)

We examine the equations of motion of double field theory and the duality manifest form of M-theory. We show the solutions of the equations of motion corresponding to null waves correspond to strings or membranes from the usual spacetime perspective. A Goldstone mode analysis of the null wave solution in double field theory produces the equations of motion of the duality manifest string.

Berkeley, Joel; Berman, David S.; Rudolph, Felix J.

2014-06-01

257

Instantons confined by monopole strings  

NASA Astrophysics Data System (ADS)

It is known that monopoles can be confined by vortex strings in d=3+1 while vortices can be confined by domain lines in d=2+1. Here, as a higher dimensional generalization of these, we show that Yang-Mills instantons can be confined by monopole strings in d=4+1. We achieve this by putting the system into the Higgs phase in which the configuration can be constructed inside a non-Abelian vortex sheet.

Nitta, Muneto

2013-03-01

258

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

USGS Publications Warehouse

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.

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

2003-01-01

259

Response of white sucker (Catostomus commersoni) to pulp and paper mill effluent in the Androscoggin River, Maine, USA.  

PubMed

Adverse effects of pulp and paper mill effluent on fish populations have been well documented in many countries over the last two decades. Some of the initial studies were at mills with conventional chlorine bleaching and no secondary effluent treatment. Following installation of secondary treatment, changes in bleaching technology to elemental chlorine-free bleaching, and other process changes, adverse effects on fish were reduced or eliminated at some mills. Because no two mills are exactly alike, it is difficult to predict adverse impacts of any given mill on fish populations. In 1994, a study of female white sucker (Catostomus commersoni) in the Androscoggin River, Maine, USA, showed induction of mixed function oxidase, reductions in gonad size and plasma estradiol, and an increase in plasma testosterone in fish downstream of discharges from three large bleached kraft pulp and paper mills, and host community municipal sewage treatment plants (STP). After all three mills switched to elemental chlorine-free bleaching in the late 1990s, studies from 2001 to 2003 found that the pattern of reproductive impacts on white sucker populations measured in 1994 was not repeated. In addition, population estimates of white sucker from 2002 to 2003 using mark-recapture techniques found that densities and biomass were well within the range of those of a reference population, and of those reported in the literature for unimpacted populations. Detailed studies immediately above and below each mill/sewage treatment plant showed no evidence of reproductive effects. However, a clear pattern of eutrophication was noted, which increased cumulatively downstream below each mill/STP. PMID:20872897

Mower, Barry F; Munkittrick, Kelly R; McMaster, Mark E; Van Beneden, Rebecca J

2011-01-01

260

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

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.

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

2009-01-01

261

A novel string field theory solving string theory by liberating left and right movers  

NASA Astrophysics Data System (ADS)

We put forward ideas to a novel string field theory based on making some "objects" that essentially describe "liberated" left- and right- mover fields ( ? + ?) and ( ? - ?) on the string. Our novel string field theory is completely definitely different from any other string theory in as far as a "null set" of information in the string field theory Fock space has been removed relatively, to the usual string field theories. So our theory is definitely new. The main progress is that we manage to make our novel string field theory provide the correct mass square spectrum for the string. We finally suggest how to obtain the Veneziano amplitude in our model.

Nielsen, Holger B.; Ninomiya, Masao

2014-05-01

262

Reactor control rod timing system  

DOEpatents

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.

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

1982-01-01

263

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

USGS Publications Warehouse

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.

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

2005-01-01

264

Physiological hepatic response to zinc oxide nanoparticle exposure in the white sucker, Catostomus commersonii.  

PubMed

Liver toxicity of commercially relevant zinc oxide nanoparticles (nZnO) was assessed in a benthic freshwater cypriniform, the white sucker (Catostomus commersonii). Exposure to nZnO caused several changes in levels of liver enzyme activity, antioxidants, and lipid peroxidation end products consistent with an oxidative stress response. Aconitase activity decreased by ~65% but tended to be restored to original levels upon supplementation with Fe(2+), indicating oxidative inactivation of the 4Fe-4S cluster. Furthermore, glucose-6-phosphate dehydrogenase activity decreased by ~29%, and glutathione levels increased by ~56%. Taken together, these suggest that nZnO induces hepatic physiological stress. Each assay was then validated by using a single liver homogenate or plasma sample that was partitioned and treated with nZnO or Zn(2+), the breakdown product of nZnO. It was found that Zn(2+), but not nZnO, increased detected glutathione reductase activity by ~14% and decreased detected malondialdehyde by ~39%. This indicates that if appreciable nZnO dissolution occurs in liver samples during processing and assay, it may skew results, with implications not only for this study, but also for a wide range of nanotoxicology studies focusing on nZnO. Finally, in vitro incubations of cell-free rat blood plasma with nZnO failed to generate any significant increase in malondialdehyde or protein carbonyl levels, or any significant decrease in ferric reducing ability of plasma. This suggests that at the level tested, any oxidative stress caused by nZnO is the result of a coordinated physiological response by the liver. PMID:24704545

Dieni, Christopher Anthony; Callaghan, Neal Ingraham; Gormley, Patrick Thomas; Butler, Kathryn Marie Alison; Maccormack, Tyson James

2014-05-01

265

Cone rod dystrophies.  

PubMed

Cone rod dystrophies (CRDs) (prevalence 1/40,000) are inherited retinal dystrophies that belong to the group of pigmentary retinopathies. CRDs are characterized by retinal pigment deposits visible on fundus examination, predominantly localized to the macular region. In contrast to typical retinitis pigmentosa (RP), also called the rod cone dystrophies (RCDs) resulting from the primary loss in rod photoreceptors and later followed by the secondary loss in cone photoreceptors, CRDs reflect the opposite sequence of events. CRD is characterized by primary cone involvement, or, sometimes, by concomitant loss of both cones and rods that explains the predominant symptoms of CRDs: decreased visual acuity, color vision defects, photoaversion and decreased sensitivity in the central visual field, later followed by progressive loss in peripheral vision and night blindness. The clinical course of CRDs is generally more severe and rapid than that of RCDs, leading to earlier legal blindness and disability. At end stage, however, CRDs do not differ from RCDs. CRDs are most frequently non syndromic, but they may also be part of several syndromes, such as Bardet Biedl syndrome and Spinocerebellar Ataxia Type 7 (SCA7). Non syndromic CRDs are genetically heterogeneous (ten cloned genes and three loci have been identified so far). The four major causative genes involved in the pathogenesis of CRDs are ABCA4 (which causes Stargardt disease and also 30 to 60% of autosomal recessive CRDs), CRX and GUCY2D (which are responsible for many reported cases of autosomal dominant CRDs), and RPGR (which causes about 2/3 of X-linked RP and also an undetermined percentage of X-linked CRDs). It is likely that highly deleterious mutations in genes that otherwise cause RP or macular dystrophy may also lead to CRDs. The diagnosis of CRDs is based on clinical history, fundus examination and electroretinogram. Molecular diagnosis can be made for some genes, genetic counseling is always advised. Currently, there is no therapy that stops the evolution of the disease or restores the vision, and the visual prognosis is poor. Management aims at slowing down the degenerative process, treating the complications and helping patients to cope with the social and psychological impact of blindness. PMID:17270046

Hamel, Christian P

2007-01-01

266

Fiber optic laser rod  

DOEpatents

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.

Erickson, G.F.

1988-04-13

267

Making Highly Pure Glass Rods  

NASA Technical Reports Server (NTRS)

Proposed quasi-containerless method for making glass rods or fibers minimizes contact between processing equipment and product. Method allows greater range of product sizes and shapes than achieved in experiments on containerless processing. Molten zone established in polycrystalline rod. Furnace sections separated, and glass rod solidifies between them. Clamp supports solid glass as it grows in length. Pulling clamp rapidly away from melt draws glass fiber. Fiber diameter controlled by adjustment of pulling rate.

Naumann, R. J.

1986-01-01

268

Automatic safety rod for reactors  

DOEpatents

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.

Germer, John H. (San Jose, CA)

1988-01-01

269

Piston and connecting rod assembly  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

270

Threading plasmonic nanoparticle strings with light.  

PubMed

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

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

2014-01-01

271

Rod Microglia: A Morphological Definition  

PubMed Central

Brain microglial morphology relates to function, with ramified microglia surveying the micro-environment and amoeboid microglia engulfing debris. One subgroup of microglia, rod microglia, have been observed in a number of pathological conditions, however neither a function nor specific morphology has been defined. Historically, rod microglia have been described intermittently as cells with a sausage-shaped soma and long, thin processes, which align adjacent to neurons. More recently, our group has described rod microglia aligning end-to-end with one another to form trains adjacent to neuronal processes. Confusion in the literature regarding rod microglia arises from some reports referring to the sausage-shaped cell body, while ignoring the spatial distribution of processes. Here, we systematically define the morphological characteristics of rod microglia that form after diffuse brain injury in the rat, which differ morphologically from the spurious rod microglia found in uninjured sham. Rod microglia in the diffuse-injured rat brain show a ratio of 1.79±0.03 cell length?cell width at day 1 post-injury, which increases to 3.35±0.05 at day 7, compared to sham (1.17±0.02). The soma length?width differs only at day 7 post-injury (2.92±0.07 length?width), compared to sham (2.49±0.05). Further analysis indicated that rod microglia may not elongate in cell length but rather narrow in cell width, and retract planar (side) processes. These morphological characteristics serve as a tool for distinguishing rod microglia from other morphologies. The function of rod microglia remains enigmatic; based on morphology we propose origins and functions for rod microglia after acute neurological insult, which may provide biomarkers or therapeutic targets.

Taylor, Samuel E.; Morganti-Kossmann, Cristina

2014-01-01

272

Ecology of bonytail and razorback sucker and the role of off-channel habitats in their recovery  

USGS Publications Warehouse

The bonytail and razorback sucker are two of four endangered mainstem fishes found in the Colorado River. Unlike the Colorado pikeminnow and humpback chub, wild populations of the bonytail and razorback sucker are either extirpated from the mainstem river or are nearly so. Agencies are aggressively stocking these fish wile repatriated fish spawn, their young are rapidly eaten by introduced predators. A decade of predator removal efforts has proved ineffective in restoring natural recruitment. Today, the presence of these species is totally dependent on stocking, suggesting both species are worse off today than when recovery efforts began nearly two decades ago. In contrast, both species readily produce young in ponds where nonnative predators are absent. Evidence shows they evolved with the ability to spawn in both flowing and standing water, which suggests isolated oxbow communities may be been an essential feature in their evolution and survival strategy. Sustainable populations during the past few decades have only occurred in isolated ponds devoid of predatory nonnative fish. Efforts to force recovery in the main channel river continue to fail due to the presence of nonnative predators that may be economically important recreational species. Off-channel sanctuaries provide research and management opportunities on a scale that are both biologically and economically realistic. Effective management of these species in small habitats appears to be the most logical approach to advance recovery in larger river reachesa?|

Mueller, Gordon A.

2006-01-01

273

Interaction rates in string gas cosmology  

SciTech Connect

We study string interaction rates in the Brandenberger-Vafa scenario, the very early universe cosmology of a gas of strings. This cosmology starts with the assumption that all spatial dimensions are compact and initially have string scale radii; some dimensions grow due to some thermal or quantum fluctuation which acts as an initial expansion velocity. Based on simple arguments from the low-energy equations of motion and string thermodynamics, we demonstrate that the interaction rates of strings are negligible, so the common assumption of thermal equilibrium cannot apply. We also present a new analysis of the cosmological evolution of strings on compact manifolds of large radius. Then we discuss modifications that should be considered to the usual Brandenberger-Vafa scenario. To confirm our simple arguments, we give a numerical calculation of the annihilation rate of winding strings. In calculating the rate, we also show that the quantum mechanics of strings in small spaces is important.

Danos, Rebecca; Frey, Andrew R.; Mazumdar, Anupam [Department of Physics, University of California, Los Angeles, Los Angeles, California 90095 (United States); California Institute of Technology, 452-48, Pasadena, California 91125 (United States); NORDITA, Blegdamsvej-17, DK-2100, Copenhagen (Denmark)

2004-11-15

274

A First Course in String Theory  

NASA Astrophysics Data System (ADS)

An accessible introduction to string theory, this book provides a detailed and self-contained demonstration of the main concepts involved. The first part deals with basic ideas, reviewing special relativity and electromagnetism while introducing the concept of extra dimensions. D-branes and the classical dynamics of relativistic strings are discussed next, and the quantization of open and closed bosonic strings in the light-cone gauge, along with a brief introduction to superstrings. The second part begins with a detailed study of D-branes followed by string thermodynamics. It discusses possible physical applications, and covers T-duality of open and closed strings, electromagnetic fields on D-branes, Born/Infeld electrodynamics, covariant string quantization and string interactions. Primarily aimed as a textbook for advanced undergraduate and beginning graduate courses, it will also be ideal for a wide range of scientists and mathematicians who are curious about string theory.

Zwiebach, Barton

2004-06-01

275

Energy and Momentum Transport in String Waves  

ERIC Educational Resources Information Center

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)

Juenker, D. W.

1976-01-01

276

Bosonic string theory with dust  

NASA Astrophysics Data System (ADS)

We study a modified bosonic string theory that has a pressureless ‘dust’ field on the string worldsheet. The dust is a real scalar field with unit gradient which breaks conformal invariance. Hamiltonian analysis reveals a time reparametrization constraint linear in the dust field momentum and a spatial diffeomorphism constraint. This feature provides a natural ‘dust time’ gauge in analogy with the parametrized particle. In this gauge we give a Fock quantization of the theory, which is complete and self-consistent in d < 26. The Hamiltonian of the theory is not a constraint; as a consequence the Hilbert space and mass spectrum are characterized by an additional parameter, and includes the usual string spectrum as a special case. The other sectors provide new particle spectra, some of which do not have tachyons.

Gegenberg, Jack; Husain, Viqar

2014-04-01

277

Insights from the downhole dynamometer database  

Microsoft Academic Search

The Downhole Dynamometer Database is a compilation of test data collected with a set of five downhole tools built by Albert Engineering under contract to Sandia National Laboratories. The downhole dynamometer tools are memory tools deployed in the sucker rod string with sensors to measure pressure, temperature, load, and acceleration. The acceleration data is processed to yield position, so that

Waggoner

1997-01-01

278

Development of the Downhole Dynamometer Database  

Microsoft Academic Search

The Downhole Dynamometer Database is a compilation of test data collected with a set of five downhole tools built by Albert Engineering under contract to Sandia National Laboratories. The downhole dynamometer tools are memory tools deployed in the sucker rod string with sensors to measure pressure, temperature, load, and acceleration. The acceleration data is processed to yield position, so that

John Waggoner; A. J. Mansure

1997-01-01

279

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...

280

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

USGS Publications Warehouse

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.

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

2014-01-01

281

Gravitational waves as string vacua II  

Microsoft Academic Search

Classical propagation of (super)strings through gravitational shock waves is analyzed. The exact classical solutions are used for quantization and for the identification of the exact quantumS-matrix describing string scattering by the wave. ThisS-matrix coincides with theS-matrix of the string-string scattering in theflat space-time for particular profile of the shock wave! This is interpreted as the generation of curved geometry from

Ctirad Klimcik

1991-01-01

282

Twenty-five questions for string theorists  

SciTech Connect

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.

Binetruy, Pierre; /Orsay, LPT; Kane, G.L.; /Michigan U., MCTP; Lykken, Joseph D.; /Fermilab; Nelson, Brent D.; /Pennsylvania U.

2005-09-01

283

Cambridge Cosmology: Cosmic Strings and Other Defects  

NSDL National Science Digital Library

This section of Cambridge Cosmology discusses cosmic strings and other defects in our Universe. It begins with phase transitions in the early Universe, and how cosmic strings and other defects formed early on. Cosmic string evolution and dynamics are discussed while looking at high-resolution numerical cosmic string simulations. Also covered are possible explanations for the origin of large-scale structures (such as galaxies) and texture models of these structures.

Shellard, Paul; Martins, Carlos; Sornborger, Andrew

284

Introduction to the theory of strings  

SciTech Connect

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

Peskin, M.E.

1985-10-01

285

Fine structure of local and axion strings  

Microsoft Academic Search

We examine the nature of the internal structure of strings arising from field theories when a global or local symmetry is spontaneously broken. The classical dynamics of these strings is represented by effective Lagrangians in which the standard Nambu-Goto term is supplemented by additional terms that are geometric in nature. In the simplest case of the local string, the new

S. M. Barr; D. Hochberg

1989-01-01

286

Topics in string theory and supersymmetry  

Microsoft Academic Search

The first six chapters of this thesis explain and examine the procedure for calculating scattering amplitudes in string theory for the bosonic and spinning string, following the formalism of Green, Schwarz, and Written. Chapter 1 gives a brief primer for bosonic and spinning string theory. In Chapters 2 and 3, the procedure for calculating bosonic scattering amplitudes in the operator

Steven Anthony Wiles

2000-01-01

287

String theory dynamics in various dimensions  

Microsoft Academic Search

The strong coupling dynamics of string theories in dimension d ? 4 are studied. It is argued, among other things, that eleven-dimensional supergravity arises as a low energy limit of the ten-dimensional Type IIA superstring, and that a recently conjectured duality between the heterotic string and Type IIA superstrings controls the strong coupling dynamics of the heterotic string in five,

Edward Witten

1995-01-01

288

Noncommutative Tachyons And String Field Theory  

Microsoft Academic Search

It has been shown recently that by turning on a large noncommutativity parameter, the description of tachyon condensation in string theory can be drastically simplified. We reconsider these issues from the standpoint of string field theory, showing that, from this point of view, the key fact is that in the limit of a large B-field, the string field algebra factors

Edward Witten

2000-01-01

289

String Field Theory Around the Tachyon Vacuum  

Microsoft Academic Search

Assuming that around the tachyon vacuum the kinetic term of cubic open string field theory is made purely of ghost operators we are led to gauge invariant actions which manifestly implement the absence of open string dynamics around this vacuum. We test this proposal by showing the existence of lump solutions of arbitrary codimension in this string field theory. The

Leonardo Rastelli; Ashoke Sen; Barton Zwiebach

2000-01-01

290

Transverse structure of the QCD string  

SciTech Connect

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.

Meyer, Harvey B. [Johannes Gutenberg Universitaet Mainz, Institut fuer Kernphysik, 55099 Mainz (Germany)

2010-11-15

291

A First Course in String Theory  

Microsoft Academic Search

An accessible introduction to string theory, this book provides a detailed and self-contained demonstration of the main concepts involved. The first part deals with basic ideas, reviewing special relativity and electromagnetism while introducing the concept of extra dimensions. D-branes and the classical dynamics of relativistic strings are discussed next, and the quantization of open and closed bosonic strings in the

Barton Zwiebach

2004-01-01

292

Conformal invariance, supersymmetry and string theory  

Microsoft Academic Search

Covariant quantization of string theories is developed in the context of conformal field theory and the BRST quantization procedure. The BRST method is used to covariantly quantize superstrings, and in particular to construct the vertex operators for string emission as well as the supersymmetry charge. The calculation of string loop diagrams is sketched. We discuss how conformal methods can be

Daniel Friedan; Emil Martinec; Stephen Shenker

1986-01-01

293

General relativity invariance and string field theory  

NASA Astrophysics Data System (ADS)

The general covariance principle in the string field theory is considered. The algebraic properties of the string Lie derivative are discussed. The string vielbein and spin connection are introduced and an action invariant under general co-ordinate transformation is proposed.

Arefeva, I. Ya.; Volovich, I. V.

1987-04-01

294

Fading of chiral strings loops to vortons  

Microsoft Academic Search

The damping of oscillations of chiral string loops due to electro- magnetic and gravitational radiation is studied. We derive expressions for energy losses into the gravitational and electromagnetic waves from the closed superconducting chiral cosmic strings of arbitrary form. For the case of large current on the string we describe the asymptotic be- haviour of chiral loops and their fading

E. Babichev; V. Dokuchaev

2002-01-01

295

Capstan equation for strings with rigidity  

Microsoft Academic Search

The effect of string rigidity on the capstan equation is considered. Two cases which cover the most likely situations are distinguished - contact of the string with the peg at a point, and contact over an arc. The analysis of these situations is facilitated by an approximation derived for the curvature for the leads of string on either side of

I M Stuart

1961-01-01

296

On string classification in data streams  

Microsoft Academic Search

String data has recently become important because of its use in a number of applications such as computational and molecular biology, protein analysis, and market basket data. In many cases, these strings contain a wide variety of sub- structures which may have physical significance for that ap- plication. For example, such substructures could represent important fragments of a DNA string

Charu C. Aggarwal; Philip S. Yu

2007-01-01

297

Primordial magnetic fields from superconducting cosmic strings  

Microsoft Academic Search

This paper explores the possibility of generation of a primordial magnetic field by a network of charged-current carrying cosmic strings. The field is created by vorticity, generated in the primordial plasma due to the strings' motion and gravitational pull. In the case of superconducting strings formed at the breaking of grand unification, it is found that strong magnetic fields of

Konstantinos Dimopoulos

1998-01-01

298

Bounds for the String Editing Problem  

Microsoft Academic Search

The string editing problem is to determine the distance between two strings as measured by the minimal cost sequence of deletions, insertions, and changes of symbols needed to transform one string into the other. The longest common subsequence problem can be viewed as a special case. Wagner and Fischer proposed an algorithm that runs in time O(nm), where n, m

C. K. Wong; Ashok K. Chandra

1976-01-01

299

Tachyon effective actions in open string theory  

Microsoft Academic Search

We argue that the Dirac–Born–Infeld (DBI) action coupled to a tachyon, that is known to reproduce some aspects of open string dynamics, can be obtained from open string theory in a certain limit, which generalizes the limit leading to the usual DBI action. This helps clarify which aspects of the full open string theory are captured by this action.

David Kutasov; Vasilis Niarchos

2003-01-01

300

Closed string tachyon condensation: an overview  

Microsoft Academic Search

These notes are an expanded version of a review paper on closed string tachyon condensation at the RTN workshop in Copenhagen in September 2003. We begin with a lightning review of open string tachyon condensation, and then proceed to review recent results on localized closed string tachyon condensation, focusing on two simple systems, C\\/Zn orbifolds and twisted circle compactifications.

Matthew Headrick; Shiraz Minwalla; Tadashi Takayanagi

2004-01-01

301

The Picture Brightens (Slightly) for String Programs  

ERIC Educational Resources Information Center

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…

Olson, Cathy Applefeld

2010-01-01

302

String duality and novel theories without gravity  

SciTech Connect

We describe some of the novel 6d quantum field theories which have been discovered in studies of string duality. The role these theories (and their 4d descendants) may play in alleviating the vacuum degeneracy problem in string theory is reviewed. The DLCQ of these field theories is presented as one concrete way of formulating them, independent of string theory.

Kachru, Shamit

1998-01-15

303

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

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.

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

2009-01-01

304

Status of rod consolidation, 1988  

SciTech Connect

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.

Bailey, W.J.

1989-01-01

305

Light Z' in heterotic string standardlike models  

NASA Astrophysics Data System (ADS)

The discovery of the Higgs boson at the LHC supports the hypothesis that the Standard Model provides an effective parametrization of all subatomic experimental data up to the Planck scale. String theory, which provides a viable perturbative approach to quantum gravity, requires for its consistency the existence of additional gauge symmetries beyond the Standard Model. The construction of heterotic string models with a viable light Z' is, however, highly constrained. We outline the construction of standardlike heterotic string models that allow for an additional Abelian gauge symmetry that may remain unbroken down to low scales. We present a string inspired model, consistent with the string constraints.

Athanasopoulos, P.; Faraggi, A. E.; Mehta, V. M.

2014-05-01

306

The Official String Theory Web Site  

NSDL National Science Digital Library

The Official String Theory Web Site, created by a group of highly educated physicists, is a great resource for everyone interested in physics and the string theory. It begins with educational and stimulating discussion about theoretical physics and the basics of string theory. Users can find out about the experimental tests and the math used by string theorists. Visitors can take a trip through the Big Bang, view amazing images of black holes, and learn about the history of string theory. Students and educators can listen to interviews of the many scientists who contributed to this informative site.

307

Cosmic string detection in radio surveys  

NASA Astrophysics Data System (ADS)

We consider the detection of cosmic strings using observations of the anisotropy of the Cosmic Microwave Background. Several methods for detecting cosmic strings are analyzed, using a threshold filter and expansion in orthogonal Haar functions. Computer simulation provides estimates of the noise present in experiments aimed at detection of cosmic strings. Attempts to detect cosmic strings were carried out using the full-sky ILC map obtained as a result of the WMAP space mission. A list of cosmic string candidates has been compiled using the Haar function method.

Sazhina, O. S.; Sementsov, V. N.; Ashimbaeva, N. T.

2014-01-01

308

Super fast hardware string matching  

Microsoft Academic Search

With the appearance of multi-gigabit network infrastructure, a typical network intrusion detection system (NIDS) has to cope with the network speed. By examining each packet flowing through a network segment, suspicious packets are detected and reported to assure security. Up to 57% of the execution time in a NIDS is found to compare string against a predefined\\/known pattern. It is

Chia-Tien Dan Lo; Yi-Gang Tai; Kleanthis Psarris; Wen-Jyi Hwang

2006-01-01

309

Localized gravity in string theory.  

PubMed

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

Karch, A; Randall, L

2001-08-01

310

String universality in ten dimensions.  

PubMed

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

Adams, Allan; Taylor, Washington; Dewolfe, Oliver

2010-08-13

311

String Universality in Ten Dimensions  

SciTech Connect

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.

Adams, Allan; Taylor, Washington; DeWolfe, Oliver [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Department of Physics, 390 UCB, University of Colorado, Boulder, Colorado 80309 (United States)

2010-08-13

312

String Physics at the LHC  

SciTech Connect

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

Anchordoqui, Luis A. [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI 53201 (United States)

2008-11-23

313

Spin chains and string theory  

Microsoft Academic Search

Recently, an impressive agreement was found between anomalous dimen- sions of certain operators in N = 4 SYM and rotating strings with two angular mo- menta in the bulk of AdS5 × S5. A one-loop field theory computation, which involves solving a Heisenberg chain by means of the Bethe ansatz agrees with the large angular momentum limit of a rotating

Martin Kruczenski

314

Black Holes in String Theory  

Microsoft Academic Search

This thesis is devoted to trying to find a microscopic quantum description of black holes. We consider black holes in string theory which is a quantum theory of gravity. We find that the ``area law'' black hole entropy for extremal and near-extremal charged black holes arises from counting microscopic configurations. We study black holes in five and four spacetime dimensions.

Juan Mart n Maldacena

1996-01-01

315

RV strings of maximum curvature  

SciTech Connect

To design an effective interceptor for a string of reentry vehicles (RV's) released by a post-boost vehicle (PBV), it is necessary to have information about possible geometries of the string when it reaches a given altitude above the target. The geometry of the string, assumed for simplicity to contain three RV's, is determined by the motion of the PBV which is controlled by varying its thrust direction. Of interest in this study is maximizing the curvature of the string, which is represented by the distance of RV{sub 2} from the line joining RV{sub 1} and RV{sub 3} when RV{sub 1} reaches the intercept attitude, subject to the constraints that all three RV's must land within 3000 ft distance of the target. The maximum curvature problem is formulated as a parameter optimization problem and solved by a nonlinear programming code known as GRG2. The thrust angles are assumed to be piecewise linear, and a total of 21 parameters is used. The maximum curvature is shown to be approximately 2900 ft. 4 refs., 8 figs.

Hull, D.G. (Texas Univ., Austin, TX (United States)); Zazworsky, R.M. (Sandia National Labs., Albuquerque, NM (United States))

1991-01-01

316

Electroweak baryogenesis with electroweak strings  

Microsoft Academic Search

If stable electroweak strings are copiously produced during the electroweak phase transition, they may contribute significantly to the presently observed baryon to entropy ratio of the universe. This analysis establishes the feasibility of implementing an electroweak baryogenesis scenario without a first order phase transition.

Robert H. Brandenberger; Anne-Christine Davis

1993-01-01

317

Group Theory for String States.  

National Technical Information Service (NTIS)

All string theories can be described in terms of an infinite number of states equally spaced in mass and their spectrum can be constructed out of harmonic oscillators of bosonic and fermionic types. It is the purpose of this lecture to provide an introduc...

P. Ramond

1985-01-01

318

Quantum foam and topological strings  

Microsoft Academic Search

We find an interpretation of the recent connection found between topological strings on Calabi-Yau threefolds and crystal melting: Summing over statistical mechanical configuration of melting crystal is equivalent to a quantum gravitational path integral involving fluctuations of Kähler geometry and topology. We show how the limit shape of the melting crystal emerges as the average geometry and topology of the

Amer Iqbal; Cumrun Vafa; Nikita Nekrasov; Andrei Okounkov

2008-01-01

319

Using spatial, seasonal, and diel drift patterns of larval Lost River suckers Deltistes luxatus (Cypriniformes: Catostomidae) and shortnose suckers Chasmistes brevirostris (Cypriniformes: Catostomidae) to help identify a site for a water withdrawal structure on the Williamson River, Oregon  

USGS Publications Warehouse

A small irrigation diversion dam near Chiloquin, Oregon, was removed and replaced with a pump station to improve fish passage for Lost River suckers (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) entering the Sprague River on their spawning migrations. During the developmental phase of the pump station, a need was identified to better understand the larval drift characteristics of these endangered catostomids in order to reduce entrainment into the irrigation system. The spatial, seasonal, and diel distribution of drifting larvae was measured during the 2004 spawning season at two proposed sites on the Williamson River where the pump station could be located. Larval drift for both species coincided with the irrigation season making them subject to entrainment into the irrigation system. Drift occurred almost exclusively at night with larvae entering the drift at sunset and exiting the drift at sunrise. Nighttime larval densities were concentrated near the surface and at midchannel at both sites. Densities were generally greater on the side of mid-channel with greater flow. During early morning sampling we detected a general shift in larval drift from surface to subsurface drift. We also observed an increase in larval densities towards the shore opposite from the proposed pump station at the upper site whereas larval densities remained high at midchannel at the lower site. During daytime sampling, the few larvae that were collected were distributed throughout the water column at both pump sites. This study found that larvae drifting during all time periods were generally distributed further across the cross section, deeper in the water column, and closer to where the proposed water withdrawal structure would be built at the downstream site when compared to the upstream site. Recommendations were provided to locate the withdrawal facility at the upstream site and operate it in a manner such that larval entrainment would likely be minimized.

Ellsworth, Craig M.; Tyler, Torrey J.; Vanderkooi, Scott P.

2010-01-01

320

Randall-Sundrum and strings  

NASA Astrophysics Data System (ADS)

We investigate stringy excitations in Randall-Sundrum effective theories for electroweak symmetry breaking arising from embedding in string theory. RS is dual to a confining gauge theory, which we expect to have “QCD strings”, or color flux tubes. Stringy constructions of RS-like theories allow us to investigate the mass of these string states, which typically grows with a small fractional power of the number of colors N of the dual gauge theory. There are two known strong constraints on N for RS-like theories. The first arises from demanding that the Standard Model gauge couplings do not have a Landau pole at low scales. The second arises from demanding that the first-order confining phase transition in the early universe is able to proceed without leaving an empty universe, i.e. that the rate of bubble nucleation is not too small. We find that these constraints on N imply that string states are generically at most a factor of a few heavier than the lightest KK states, and we cannot self-consistently remain in the limit N,? ? 1. We examine various string constructions of AdS or RS-like backgrounds, including orbifolds, theories on M5-branes, theories on D4-branes, and the recent F-theory construction of Polchinski and Silverstein. In every case we find that there are strong bounds on the mass of new stringy states. We briefly discuss important phenomenological implications due to the presence of such light stringy excitations, such as precision electroweak and flavor observables, as well as collider signals.

Reece, Matthew; Wang, Lian-Tao

2010-07-01

321

Nuclear design of Helical Cruciform Fuel rods  

SciTech Connect

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)

Shirvan, K.; Kazimi, M. S. [Dept. of Nuclear Engineering and Sciences, Massachusetts Inst. of Technology, 77 Massachusetts Avenue 24-215 (United States)

2012-07-01

322

Oxidative stress responses in longnose sucker (Catostomus catostomus) exposed to pulp and paper mill and municipal sewage effluents.  

PubMed

While recent evidence indicates that the generation of reactive oxygen species (ROS) and associated oxidative damage are frequently observed in fish populations with exposure to pulp and paper mill effluents, the potential for ROS generation from municipal sewage effluents has not been addressed. This study investigates the utility of measures of oxidative stress in delineating the effects of both pulp and paper mill and municipal sewage discharges. Longnose sucker (Catostomus catostomus) were collected below three pulp and paper mill and two municipal sewage effluent discharges over a 3-year period within the Wapiti and Athabasca River systems in northern Alberta. Biochemical responses in longnose sucker varied between the two rivers systems, with more pronounced changes occurring within the Wapiti River. Of the suite of biochemical parameters examined, fatty acyl-CoA oxidase (FAO) activity was the most sensitive indicator of pulp and paper mill exposure, but was only infrequently induced with exposure to municipal sewage effluent. Hepatic and gonadal 2-thiobarbituric acid reactive substances, lipid hydroperoxides, and hepatic free iron were less consistently elevated with exposure to pulp and paper mill effluent than FAO activity, and were also only infrequently altered with sewage effluent exposure. Hepatic ascorbic acid, liver somatic index, and condition factor were consistently altered with exposure to both sewage and pulp and paper mill effluents. While specific biochemical and organismal responses varied with effluents and time, the collective suite of oxidative stress endpoints proved to be useful tools in identifying relative influences of municipal sewage and pulp and paper mill effluent on fish populations in adjacent receiving waters. PMID:15063075

Oakes, Ken D; McMaster, Mark E; Van Der Kraak, Glen J

2004-04-28

323

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

SciTech Connect

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

Arslanargin, Ayse [Bogazici University, Department of Physics, 34342, Bebek, Istanbul (Turkey); Kaya, Ali [Bogazici University, Department of Physics, 34342, Bebek, Istanbul (Turkey); Feza Guersey Institute, Emek Mah. No:68, Cengelkoey, Istanbul (Turkey)

2009-03-15

324

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

NASA Astrophysics Data System (ADS)

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

Arslanarg?n, Ay?e; Kaya, Ali

2009-03-01

325

Particle-tracking investigation of the retention of sucker larvae emerging from spawning grounds in Upper Klamath Lake, Oregon  

USGS Publications Warehouse

This study had two objectives: (1) to use the results of an individual-based particle-tracking model of larval sucker dispersal through the Williamson River delta and Upper Klamath Lake, Oregon, to interpret field data collected throughout Upper Klamath and Agency Lakes, and (2) to use the model to investigate the retention of sucker larvae in the system as a function of Williamson River flow, wind, and lake elevation. This is a follow-up study to work reported in Wood and others (2014) in which the hydrodynamic model of Upper Klamath Lake was combined with an individual-based, particle-tracking model of larval fish entering the lake from spawning areas in the Williamson River. In the previous study, the performance of the model was evaluated through comparison with field data comprising larval sucker distribution collected in 2009 by The Nature Conservancy, Oregon State University (OSU), and the U.S. Geological Survey, primarily from the (at that time) recently reconnected Williamson River Delta and along the eastern shoreline of Upper Klamath Lake, surrounding the old river mouth. The previous study demonstrated that the validation of the model with field data was moderately successful and that the model was useful for describing the broad patterns of larval dispersal from the river, at least in the areas surrounding the river channel immediately downstream of the spawning areas and along the shoreline where larvae enter the lake. In this study, field data collected by OSU throughout the main body of Upper Klamath Lake, and not just around the Williamson River Delta, were compared to model simulation results. Because the field data were collected throughout the lake, it was necessary to include in the simulations larvae spawned at eastern shoreline springs that were not included in the earlier studies. A complicating factor was that the OSU collected data throughout the main body of the lake in 2011 and 2012, after the end of several years of larval drift collection in the Williamson River by the U.S. Geological Survey. Those larval drift data provided necessary boundary-condition information for the earlier studies, but there were no measured boundary conditions for larval input into model simulations during the years of this study (2011?12). Therefore, we developed a method to estimate a time series of larval drift in the Williamson River, and of the emergence of larvae from the gravel at the eastern shoreline springs, that captured the approximate timing of the larval pulse of the Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) and the relative magnitude of the pulses by species and spawning location. The method is not able to predict larval drift on any given day, but it can reasonably predict the approximate temporal progression of the larval drift through the season, based on counts of adult suckers returning to spawn. The accuracy in the timing of the larval pulses is not better than about plus or minus 5 days. Model results and field data were consistent in the basic progression of both catch per unit effort (CPUE) and larval length through time. The model simulation results also duplicated some of the characteristics of the spatial patterns of density in the field data, notably the tendency for high larval densities closer to the eastern and western shorelines. However, the model simulations could not explain high densities in the northern part of the lake or far into Ball Bay, locations that are far from the source of larvae in the Williamson River or eastern shoreline springs (as measured along the predominant transport pathways simulated in the model). This suggests the possibility of unaccounted-for spawning areas in the northern part of the lake and also that the period during which larvae are transported passively by the currents is shorter than the 46 days simulated in the model. Similarly, the progression of larval lengths in the field data is not a simple progression from smaller to larger fish away from sources in the river and springs, as simulated by the parti

Wood, Tamara M.; Wherry, Susan A.; Simon, David C.; Markle, Douglas F.

2014-01-01

326

MORPHOGENESIS OF THE RETINAL RODS  

PubMed Central

The morphogenesis of the retinal rods has been studied with the electron microscope in white mice from birth up to the 16th day of age. Observations have been mainly concentrated on specimens of the 8th and 12th days and on the differentiation of the inner and outer segments of the retinal rods. In the morphogenesis of the outer segment three main stages have been considered. The first stage consists in the development of a primitive cilium projecting from a bulge of protoplasm which constitutes the primordium of the inner segment. A basal body, nine pairs of peripheral filaments, a surface membrane, and a matrix filled with a fine vesicular material have been recognized as components of the primitive cilium. The vesicles are called "morphogenetic material" because it is believed that they represent the macromolecular primordium of the rod sacs of the future outer segment. The second stage corresponds to the great enlargment of the apical region of the primitive cilium due to the rapid building up of the lamellar material of the rod sacs. The primitive rod sacs appear to be connected with the ciliary filaments. The basal portion of the primitive cilium remains undifferentiated and constitutes the connecting cilium of the adult rod (1). The third stage consists in the remodelling and reorientation of the rod sacs into their permanent transverse disposition. This process starts in the middle portion of the outer segments and proceeds towards both extremities which can be considered as zones of growth of the outer segment. The inner segment is at the beginning a bulge of protoplasm containing unoriented mitochondria, a basal body, a small Golgi zone, and numerous dense particles. Then this region becomes elongated and the different components assume the stratified disposition found in the adult (1). The demonstration that the entire outer segment of the rod cell is the result of the differentiation of a primitive cilium is discussed in view of the conflicting interpretations found in the literature. The possible macromolecular mechanisms that may be involved in the submicroscopic morphogenesis of the rod sacs are discussed and the possible role of the morphogenetic material is considered. The results described in this paper confirm and extend the interpretation of the submicroscopic morphology of the adult rod cell as presented in a previous paper (1).

De Robertis, E.

1956-01-01

327

Effects of Chiloquin Dam on spawning distribution and larval emigration of Lost River, shortnose, and Klamath largescale suckers in the Williamson and Sprague Rivers, Oregon  

USGS Publications Warehouse

Chiloquin Dam was constructed in 1914 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 (Deltistes luxatusChasmistes brevirostris) suckers, as well as other fish species. In 2002, the Bureau of Reclamation led a working group that examined several alternatives to improve fish passage at Chiloquin Dam. Ultimately it was decided that dam removal was the best alternative and the dam was removed in the summer of 2008. The U.S. Geological Survey conducted a long-term study on the spawning ecology of Lost River, shortnose, and Klamath largescale suckers (Catostomus snyderi) in the Sprague and lower Williamson Rivers from 2004 to 2010. The objective of this study was to evaluate shifts in spawning distribution following the removal of Chiloquin Dam. Radio telemetry was used in conjunction with larval production data and detections of fish tagged with passive integrated transponders (PIT tags) to evaluate whether dam removal resulted in increased utilization of spawning habitat farther upstream in the Sprague River. Increased densities of drifting larvae were observed at a site in the lower Williamson River after the dam was removed, but no substantial changes occurred upstream of the former dam site. Adult spawning migrations primarily were influenced by water temperature and did not change with the removal of the dam. Emigration of larvae consistently occurred about 3-4 weeks after adults migrated into a section of river. Detections of PIT-tagged fish showed increases in the numbers of all three suckers that migrated upstream of the dam site following removal, but the increases for Lost River and shortnose suckers were relatively small compared to the total number of fish that made a spawning migration in a given season. Increases for Klamath largescale suckers were more substantial. Post-dam removal monitoring only included 2 years with below average river discharge during the spawning season; data from years with higher flows may provide a different perspective on the effects of dam removal on the spawning migrations of the two endangered sucker species.

Martin, Barbara A.; Hewitt, David A.; Ellsworth, Craig M.

2013-01-01

328

Effects of pool formation and flash flooding on relative abundance of young-of-year flannelmouth suckers in the Paria River, Arizona  

USGS Publications Warehouse

Flannelmouth sucker, Catostomus latipinnis, a fish endemic to the Colorado River basin in the western United States, appears to experience poor recruitment to adult size in the Colorado River, downstream of Glen Canyon Dam. Lack or impermanence of rearing areas for young-of-year (YOY) fish is hypothesized to be the problem. Knowing the importance of tributary mouths as rearing areas in other river systems, we studied use of the mouth of the Paria River, a tributary of the Colorado River, by YOY flannelmouth suckers, and the availability of rearing area in the mouth at different flow levels in the Colorado River in 1996 and 1997. We also examined the relationship between flash floods in the Paria River and catch-per-unit-effort (CPUE) of YOY in the Paria River between 1991 and 1996. Maximum mean daily discharge in the Paria River was inversely correlated with CPUE of YOY flannelmouth suckers (Spearman Rho = -0.9856, p = 0.0003) during their critical rearing period (15 March-30 June). Thus, it appears that YOY flannelmouth suckers rear longer in the Paria River in years when flash flooding is minimal. Recruitment of YOY flannelmouth suckers at the Paria River may also be improved by enhancing pool formation during spring and summer rearing seasons. YOY flannelmouth sucker was captured in a pool created by high Colorado River flows (??? 336 m3/s) that inundated the mouth of the Paria River during spring and summer, 1996. In 1997, high flows (about 550-750 m3/s) in the Colorado River during winter and spring initially inundated the Paria River and formed a pool in the mouth. However, these high flows eventually caused 0.5-1.0 m of suspended sediment from the incoming Paria River to deposit in the mouth. Thus, despite higher flows than 1996, the slackwater area formed only occasionally in 1997. Differences in pool formation between 1996 and 1997 demonstrate that pool formation cannot be inferred solely from Colorado River flows. ?? 2001 John Wiley & Sons, Ltd.

Thieme, M. L.; McIvor, C. C.; Brouder, M. J.; Hoffnagle, T. L.

2001-01-01

329

Exotic branes in string theory  

NASA Astrophysics Data System (ADS)

Besides the familiar D-branes, string theory contains a vast number of other non-perturbative objects. While a complete classification is lacking, many of these objects are related to each other through various dualities. Codimension two objects play a special role, because their charges are no longer additive but are instead expressed in terms of holonomies of scalar fields, which is given by an element of the relevant duality group. In this paper we present a detailed exposition of these “exotic” objects, the charges they carry, and their connection to non-geometric compactifications. Despite the name “exotic branes”, these objects are in fact ubiquitous in string theory, as they can automatically appear when describing bound states of conventional branes, and as such may be of particular importance in describing the microscopic degrees of freedom of black holes.

de Boer, Jan; Shigemori, Masaki

2013-11-01

330

Filter for a drill string  

DOEpatents

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.

Hall, David R. (Provo, UT); Pixton, David S. (Lehi, UT); Briscoe, Michael (Lehi, UT); McPherson, James (Sandy, UT)

2007-12-04

331

Shape of cosmic string loops  

SciTech Connect

Complicated cosmic string loops will fragment until they reach simple, nonintersecting ('stable') configurations. Through extensive numerical study we characterize these attractor loop shapes including their length, velocity, kink, and cusp distributions. We find that an initial loop containing M harmonic modes will, on average, split into 3M stable loops. These stable loops are approximately described by the degenerate kinky loop, which is planar and rectangular, independently of the number of modes on the initial loop. This is confirmed by an analytic construction of a stable family of perturbed degenerate kinky loops. The average stable loop is also found to have a 40% chance of containing a cusp. We examine the properties of stable loops of different lengths and find only slight variation. Finally we develop a new analytic scheme to explicitly solve the string constraint equations.

Copi, Craig J.; Vachaspati, Tanmay [CERCA, Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079 (United States); Physics Department, Arizona State University, Tempe, Arizona 85287 (United States)

2011-01-15

332

Macroscopic constraints on string unification  

SciTech Connect

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.

Taylor, T.R.

1989-03-01

333

Curved branes from string dualities  

Microsoft Academic Search

We describe a simple method for generating new string solutions for which the brane worldvolume is a curved space. As a starting point we use solutions with NS-NS charges combined with two-dimensional CFTs representing different parts of spacetime. We illustrate our method with many examples, some of which are associated with conformally invariant sigma models. Using U-duality, we also obtain

G. Papadopoulos; J. G. Russo; A. A. Tseytlin

2000-01-01

334

Counting strings, wound and bound  

NASA Astrophysics Data System (ADS)

We analyze zero mode counting problems for Dirac operators that find their origin in string theory backgrounds. A first class of quantum mechanical models for which we compute the number of ground states arises from a string winding an isometric direction in a geometry, taking into account its energy due to tension. Alternatively, the models arise from deforming marginal bound states of a string winding a circle, and moving in an orthogonal geometry. After deformation, the number of bound states is again counted by the zero modes of a Dirac operator. We count these bound states in even dimensional asymptotically linear dilaton backgrounds as well as in Euclidean Taub-NUT. We show multiple pole behavior in the fugacities keeping track of a U(1) charge. We also discuss a second class of counting problems that arises when these backgrounds are deformed via the application of a heterotic duality transformation. We discuss applications of our results to Appell-Lerch sums and the counting of domain wall bound states.

Ashok, Sujay K.; Nampuri, Suresh; Troost, Jan

2013-04-01

335

Nuclear Force from String Theory  

NASA Astrophysics Data System (ADS)

We compute the nuclear force in a holographic model of QCD on the basis of a D4-D8 brane configuration in type IIA string theory. The repulsive core of nucleons is important in nuclear physics, but its origin has not been well understood in strongly coupled QCD. We find that the string theory via gauge/string duality deduces this repulsive core at a short distance between nucleons. Since baryons in the model are realized as solitons given by Yang-Mills instanton configuration on flavor D8-branes, ADHM construction of two instantons probes well the nucleon interaction at short scale, which provides the nuclear force quantitatively. We obtain a central force, as well as a tensor force, which is strongly repulsive as suggested in experiments and lattice results. In particular, the nucleon-nucleon potential V(r) (as a function of the distance) scales as r^{-2}, which is peculiar to the holographic model. We compare our results with the one-boson exchange model using the nu cleon-nucleon-meson coupling obtained in our previous paper [K. Hashimoto, T. Sakai and S. Sugimoto, Prog. Theor. Phys. 120 (2008), 1093, arXiv:0806.3122].

Hashimoto, K.; Sakai, T.; Sugimoto, S.

2009-08-01

336

Large-spin expansions of GKP strings  

NASA Astrophysics Data System (ADS)

We demonstrate that the large-spin expansion of the energy of Gubser-Klebanov-Polyakov (GKP) strings that rotate in ? × S2 and AdS3 can be expressed in terms of Lambert's W-function. We compute the leading, subleading and next-to-subleading series of exponential corrections to the infinite-volume dispersion relation of GKP strings that rotate in ? × S2. These strings are dual to the long = 4 SYM operators +… and provide their scaling dimensions at strong coupling. We also show that the strings obey a short-long (strings) duality. For the folded GKP strings that spin inside AdS3 and are dual to twist-2 operators, we confirm the known formulas for the leading and next-to-leading coefficients of their anomalous dimensions and derive the corresponding expressions for the next-to-next-to-leading coefficients.

Floratos, Emmanuel; Georgiou, George; Linardopoulos, Georgios

2014-03-01

337

p-adic string theories provide lattice Discretization to the ordinary string worldsheet.  

PubMed

A class of models called p-adic strings is useful in understanding the tachyonic instability of string theory. These are found to be empirically related to the ordinary strings in the p-->1 limit. We propose that these models provide discretization for the string worldsheet and argue that the limit is naturally thought of as a continuum limit in the sense of the renormalization group. PMID:17155316

Ghoshal, Debashis

2006-10-13

338

p-adic String Theories Provide Lattice Discretization to the Ordinary String Worldsheet  

SciTech Connect

A class of models called p-adic strings is useful in understanding the tachyonic instability of string theory. These are found to be empirically related to the ordinary strings in the p{yields}1 limit. We propose that these models provide discretization for the string worldsheet and argue that the limit is naturally thought of as a continuum limit in the sense of the renormalization group.

Ghoshal, Debashis [Harish-Chandra Research Institute, Chhatnag Road, Allahabad 211019 (India)

2006-10-13

339

Super-horizon cosmic string correlations  

Microsoft Academic Search

When gauged cosmic strings form in a symmetry-breaking phase transition, the gauge field configuration at the time becomes imprinted in the spatial string distribution by the flux trapping mechanism. Causality and flux conservation suggest that quantum and thermal gauge field fluctuations give rise to long-range super-horizon correlations in the string network. Classical field theory simulations in the Abelian Higgs model

Rajantie; Arttu

2009-01-01

340

From matrices to strings and back  

Microsoft Academic Search

We discuss an explicit construction of a string dual for the Gaussian matrix model. Starting from the matrix model and employing\\u000a Strebel differentials techniques we deduce hints about the structure of the dual string. Next, following these hints a worldheet\\u000a theory is constructed. The correlators in this string theory are assumed to localize on a finite set of points in

Shlomo S. Razamat; C. N. Yang

2010-01-01

341

String Fragmentation Model in Space Radiation Problems  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

342

Orbifold SUSY GUT from the Heterotic String  

SciTech Connect

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.

Kyae, Bumseok [Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747 (Korea, Republic of)

2008-11-23

343

Monopoles and strings in noncommutative gauge theory  

Microsoft Academic Search

We study some non-perturbative aspects of non-commutative gauge theories. We find analytic solutions of the equations of motion, for non-commutative U(1) gauge theory, that describe magnetic monopoles with a finite tension string attached. These solutions are non singular, finite and sourceless. We identify the string with the projection of a D-string ending on a D3-brane in the presence of a

David J. Gross; Nikita A. Nekrasov

2000-01-01

344

Nonrelativistic CFT and semi-classical strings  

Microsoft Academic Search

We study different features of 3D non-relativistic CFT using gravity description. As the corresponding gravity solution can be embedded into the type IIB string theory, we study semi-classical closed\\/open strings in this background. In particular we consider folded rotating and circular pulsating closed strings where we find the anomalous dimension of the dual operators as a function of their quantum

Amin Akhavan; Mohsen Alishahiha; Ali Davody; Ali Vahedi

2009-01-01

345

Comment on 'Quantum string seal is insecure'  

SciTech Connect

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

He Guangping [School of Physics and Engineering and Advanced Research Center, Sun Yat-sen University, Guangzhou 510275 (China)

2007-11-15

346

Iconic Indexing by 2-D Strings  

Microsoft Academic Search

In this paper, we describe a new way of representing a symbolic picture by a two-dimensional string. A picture query can also be specified as a 2-D string. The problem of pictorial information retrieval then becomes a problem of 2-D subsequence matching. We present algorithms for encoding a symbolic picture into its 2-D string representation, reconstructing a picture from its

Shi-Kuo Chang; Qing-Yun Shi; Cheng-Wen Yan

1987-01-01

347

Programmable Assembly With Universally Foldable Strings (Moteins)  

Microsoft Academic Search

Understanding how linear strings fold into 2-D and 3-D shapes has been a long sought goal in many fields of both academia and industry. This paper presents a technique to design self-assembling and self-reconfigurable systems that are composed of strings of very simple robotic modules. We show that physical strings that are composed of a small set of discrete polygonal

Kenneth C. Cheung; Erik D. Demaine; Jonathan R. Bachrach; Saul Griffith

2011-01-01

348

Active damping of a vibrating string  

Microsoft Academic Search

This paper presents an investigation of active damping of the vertical and horizontal transverse modes of a rigidly-terminated vibrating string. A state-space model that emulates the behavior of the string is introduced, and we explain the theory behind band pass filter control and proportional-integral-derivative (PID) control as applied to a vibrating string. After describing the characteristics of various actuators and

Edgar J. Berdahl; Julius O. Smith III

349

Quantum fluctuations of the superconducting cosmic string  

NASA Technical Reports Server (NTRS)

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.

Zhang, Shoucheng

1987-01-01

350

Quantum corrections to the string Bethe ansatz  

Microsoft Academic Search

One-loop corrections to the energy of semiclassical rotating strings contain both analytic and non-analytic terms in the 't Hooft coupling. Analytic contributions agree with the prediction from the string Bethe ansatz based on the classical S-matrix, but in order to include non-analytic contributions quantum corrections are required. We find a general expression for the first quantum correction to the string

Rafael Hernández; Esperanza López

2006-01-01

351

Cosmological string theory with thermal energy  

NASA Astrophysics Data System (ADS)

An attempt to construct a cosmological scenario directly from string theory is made. Cosmological string theory was presented by Antoniadis, Bachas, Ellis and Nanopoulos. They also expect loop effects on cosmological string theory. In this paper, we point out the other importance of the one-loop effect, the finite temperature effect. The equations of motion for background geometry at finite temperature is given. We address a problem on derivation of the effective action at non-zero temperature.

Shiraishi, Kiyoshi

1988-09-01

352

Advanced gray rod control assembly  

DOEpatents

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.

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

353

Spontaneous knotting of an agitated string  

PubMed Central

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

Raymer, Dorian M.; Smith, Douglas E.

2007-01-01

354

Super-horizon cosmic string correlations  

SciTech Connect

When gauged cosmic strings form in a symmetry-breaking phase transition, the gauge field configuration at the time becomes imprinted in the spatial string distribution by the flux trapping mechanism. Causality and flux conservation suggest that quantum and thermal gauge field fluctuations give rise to long-range super-horizon correlations in the string network. Classical field theory simulations in the Abelian Higgs model confirm this finding. In contrast, the Kibble-Zurek mechanism, which most cosmic string studies are based on, only gives rise to short-distance, subhorizon correlations. These results may have implications for cosmology, and it may also be possible to test them in superconductor experiments.

Rajantie, Arttu [Department of Physics, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom)

2009-02-15

355

Transport equation for Nambu-Goto strings  

NASA Astrophysics Data System (ADS)

We consider a covariant approach to coarse graining a network of interacting Nambu-Goto strings. A transport equation is constructed for a spatially flat Friedmann universe. In Minkowski space and with no spatial dependence this model agrees with a previous model. Thus it likewise converges to an equilibrium with a factorizability property. We present an argument that this property does not depend on a "string chaos" assumption on the correlations between strings. And in contrast to the earlier model, this transport equation agrees with conservation equations for a fluid of strings derived from a different perspective.

Schubring, Daniel; Vanchurin, Vitaly

2014-04-01

356

Non-critical string field theory with non-orientable string interactions.  

National Technical Information Service (NTIS)

We study the non-critical string field theory with non-orientable string interactions by using the transfer matrix formalism in the dynamical triangulation. For any value of c (total central charge of matter), we have constructed the non-orientable string...

Y. Watabiki

1994-01-01

357

Exposure of fish to biologically treated bleached-kraft effluent; 1: Biochemical, physiological and pathological assessment of Rocky Mountain whitefish (Prosopium williamsoni) and longnose sucker (Catostomus catostomus)  

Microsoft Academic Search

A suite of biochemical, physiological, and pathological measures was used to assess possible effects of exposure to bleached-kraft mill effluent (BKME) on wild longnose sucker (Catostomus catostomus=LS) and mountain whitefish (Prosopium williamsoni=MW) in the Wapiti\\/Smoke River system, as compared to similar populations in a reference river system without BKME inputs. Individual fish body burden data were examined for correlations between

P. J. Kloepper-Sams; J. W. Owens; S. M. Swanson; T. Marchant; R. Schryer

1994-01-01

358

Survey of receiving-water environmental impacts associated with discharges from pulp mills; 3: Polychlorinated dioxins and furans in muscle and liver of white sucker (Catostomus commersoni)  

Microsoft Academic Search

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were measured in white sucker liver samples from seven pulp and paper mill sites, and three reference sites in Ontario. The mills included five bleached-kraft mills, with and without secondary treatment, and two sulfite-mechanical mills. 2,3,7,8-T[sub 4]CDD and 2,3,7,8-T[sub 4]CDF were the dominant congeners detected in both liver and fillet samples at all of

Mark R. Servos; Susan Y. Huestis; D. Michael Whittle; K. R. Munkittrick; G. J. Van Der Kraak

1994-01-01

359

Survival of Lost River Suckers ( Deltistes luxatus ) Challenged with Flavobacterium columnare During Exposure to Sublethal Ammonia Concentrations at pH 9.5  

Microsoft Academic Search

The Lost River sucker (Deltistes luxatus) is a federally listed, endangered species inhabiting the hypereutrophic waters of Upper Klamath Lake in southern Oregon,\\u000a USA. High pH (?10) and elevated ammonia concentrations (?1 mg NH3-N\\/L) often occur during blooms of cyanobacteria (Aphanizomenon flos-aquae) in the lake, with major fish kills sometimes following a mid- or late-summer “crash” of the cyanobacterial population.

Jeffrey M. Morris; Elaine Snyder-Conn; J. Scott Foott; Richard A. Holt; Michael J. Suedkamp; Hilary M. Lease; Susan J. Clearwater; Joseph S. Meyer

2006-01-01

360

Bosonic and Baryonic String Theory in Quantum Chromodynamics  

SciTech Connect

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.

Kuti, Julius [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)

2007-02-27

361

Cool Hot Rod (Thermal Expansion)  

NSDL National Science Digital Library

The phenomenon is thermal expansion of copper. This demonstration allows an observer to see the effect of heating (and cooling) a copper tube. When heated, the copper tube lengthens and thickens. When cooled, the tube shrinks. The lengthening of the rod rotates a toothpick with an attached flag to make the expansion visible and measurable.

362

Investigation of Lightning Rod Shielding Angle  

NASA Astrophysics Data System (ADS)

This paper studies those parameters affecting the shielding angle of the lightning rod (Franklin Rod) above very tall buildings. It was recommended that the shielding angle of the lightning rod is about 45°?60°. The downward lightning leader is modeled by using discrete line charges to consider the exponential distribution of charges through the downward leader. The voltage condition used by Rizk is used to investigate the inception of the upward lightning leader. Different air conditions (relative air density and air humidity) are considered for more practical simulation. The influences of lightning parameters and lightning rod height on the shielding angle are studied. The results shows that, lightning leader parameters, lightning rod height and ground slope have series effects on the lightning rod shielding angle. Based on the results, a lightning rod shielding angle for shielding design is recommended to decrease the lightning stroke to the lightning rod.

Nayel, Mohamed

363

Strings on eight-orbifolds  

NASA Astrophysics Data System (ADS)

We present several examples of T/P orbifolds with P?SU. We compute their Hodge numbers and consider turning on discrete torsion. We then study supersymmetric compactifications of type II, heterotic, and type I strings on these orbifolds. Heterotic compactifications to D=2 have a B-field tadpole with coefficient given by that of the anomaly polynomial. In the SO heterotic with standard embedding the tadpole is absent provided the internal space has a precise value of the Euler number. Guided by their relation to type I, we find tadpole-free SO heterotic orbifolds with non-standard embedding.

Font, Anamaría; López, José Antonio

2004-12-01

364

Heavy ions and string theory  

NASA Astrophysics Data System (ADS)

We review a selection of recent developments in the application of ideas of string theory to heavy ion physics. Our topics divide naturally into equilibrium and non-equilibrium phenomena. On the non-equilibrium side, we discuss generalizations of Bjorken flow, numerical simulations of black hole formation in asymptotically anti-de Sitter geometries, equilibration in the dual field theory, and hard probes. On the equilibrium side, we summarize improved holographic QCD, extraction of transport coefficients, inclusion of chemical potentials, and approaches to the phase diagram. We close with some possible directions for future research.

DeWolfe, Oliver; Gubser, Steven S.; Rosen, Christopher; Teaney, Derek

2014-03-01

365

Topological amplitudes in string theory  

Microsoft Academic Search

We show that certain type II string amplitudes at genus $g$ are given by the\\u000atopological partition function $F_g$ discussed recently by Bershadsky, Cecotti,\\u000aOoguri and Vafa. These amplitudes give rise to a term in the four-dimensional\\u000aeffective action of the form $\\\\sum_g F_g W^{2g}$, where $W$ is the chiral\\u000asuperfield of $N=2$ supergravitational multiplet. The holomorphic anomaly of\\u000a$F_g$

I. Antoniadis; E. Gavab; K. S. Narainc; T. R. Taylor

1994-01-01

366

Extraordinary vacuum black string solutions  

SciTech Connect

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.

Kim, Hyeong-Chan; Lee, Jungjai [Department of Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Department of Physics, Daejin University, Pocheon, 487-711 (Korea, Republic of)

2008-01-15

367

String inflation after Planck 2013  

NASA Astrophysics Data System (ADS)

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.

Burgess, C. P.; Cicoli, M.; Quevedo, F.

2013-11-01

368

Relativistic String Theory. 1. Auxiliary Spectral Problem.  

National Technical Information Service (NTIS)

The theory of relativistic string is considered from the point of view of auxiliary spectral problem. The dynamical variables of string are divided into the external and internal ones and for the former an auxiliary problem is formulated. Futher the spect...

G. P. Pron'ko

1985-01-01

369

Recent Progress in String Inflationary Cosmology  

SciTech Connect

Super-inflation driven by dilaton/moduli kinetic energy is naturally realized in compactified string theory. Discussed are selected topics of recent development in string inflationary cosmology: kinematics of super-inflation, graceful exit triggered by quantum back reaction, and classical and quantum power spectra of density and metric perturbations.

Rey, Soo-Jong

2003-05-23

370

From surface roughening to QCD string theory  

SciTech Connect

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

Keisuke Jimmy Juge et al.

2001-05-23

371

More about bosonic string with topological term.  

National Technical Information Service (NTIS)

We study a model of a bosonic string in a specific antisymmetric background. It is shown that the action in the conformal gauge possesses the same residual (omega)(sub (infinity)) symmetry as the one for the ordinary bosonic string. Static solutions to th...

R. P. Zaikov S. I. Zlatev

1994-01-01

372

Generalized Dirac Equations for String Fields.  

National Technical Information Service (NTIS)

A covariant string field theory is defined as a theory of line functionals which reproduces Nambu-Goto string dynamics in the x sup 0 = tau gauge. Working within a framwork of manifest reparametrization invariance, a generalized Dirac equation for free cl...

L. Carson Y. Hosotani

1986-01-01

373

Quantum space foam and string theory  

SciTech Connect

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.

Nekrasov, Nikita [IHES, 35, Route de Chartres, Bures-sur-Yvette, F-91440 (France)

2006-11-03

374

String Theory: Big Problem for Small Size  

ERIC Educational Resources Information Center

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…

Sahoo, S.

2009-01-01

375

Noncommutative geometry from strings and branes  

Microsoft Academic Search

Noncommutative torus compactification of Matrix model is shown to be a direct consequence of quantization of the open strings attached to a D-membrane with a non-vanishing background B field. We calculate the BPS spectrum of such a brane system using both string theory results and DBI action. The DBI action leads to a new transformation property of the compactification radii

Farhad Ardalan; Hessamaddin Arfaei; Mohammad M. Sheikh-Jabbari

1999-01-01

376

Micro string resonators as temperature sensors  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

377

Closed strings from decaying D-branes  

Microsoft Academic Search

We compute the emission of closed string radiation from homogeneous rolling tachyons. For an unstable decaying Dp-brane the radiated energy is infinite to leading order for p 2. The closed string state produced by a decaying brane is closely related to the state produced by D-instantons at a critical Euclidean distance from t = 0. In the case of a

Neil Lambert; Hong Liu; Juan Maldacena

2007-01-01

378

A Pedestrian Approach to Covariant String Theory  

Microsoft Academic Search

Ever since Professor Nambu identified the Veneziano amplitude as stemming from the antics of a string, there has been a growing amount of interest in the subject. In fact the most recent view holds that consistency between Quantum Mechanics and General Relativity may be achieved only within the framework of string theory, barring unseemly modifications of Quantum Mechanics at Planckian

Pierre Ramond

1986-01-01

379

Computer Simulations of Coupled Piano Strings  

Microsoft Academic Search

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. \\

Destiny L. Albert

1997-01-01

380

A Computer String-Grammar of English.  

ERIC Educational Resources Information Center

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…

Sager, Naomi

381

Density fluctuations from strings and galaxy formation  

NASA Technical Reports Server (NTRS)

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.

Vilenkin, A.; Shafi, Q.

1983-01-01

382

Fast Kernels for Inexact String Matching  

Microsoft Academic Search

We introduce several new families of string kernels designed in par- ticular for use with support vector machines (SVMs) for classification of protein sequence data. These kernels - restricted gappy kernels, substitution kernels, and wildcard kernels - are based on feature spaces indexed byk-length subsequences from the string alphabet (or the alphabet augmented by a wildcard character), and hence they

Christina S. Leslie; Rui Kuang

2003-01-01

383

Interesting Properties of Low-Energy Strings  

Microsoft Academic Search

We begin this thesis with a study of anomalies in type-I string theory. The gauge, mixed and gravitational anomalies are calculated in the full string theory using the covariant RNS operator formalism. All anomalies are shown to cancel among the various one loop diagrams when the gauge group is SO(32). We clear up some points in these one loop calculations

James T. Liu

1991-01-01

384

New string theories and their generation number  

NASA Astrophysics Data System (ADS)

New heterotic string theories in four dimensions are constructed by tensoring a nonstandard SCFT along with some minimal SCFTs. All such theories are identified and their particle generation number is found. We prove that from the infinite number of new heterotic string theories only the {6} theory predicts three generations as seen in nature which makes it an interesting candidate for further study.

Genish, Arel; Gepner, Doron

2014-08-01

385

Plucked String on a Shoestring Budget  

ERIC Educational Resources Information Center

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…

Gluck, Paul

2009-01-01

386

Production cross section of rotating string  

Microsoft Academic Search

We calculate production cross sections of a single rotating string from a collision of two light states in bosonic string theory. We find that the cross sections are written in terms of the modified Bessel function of the first kind with the degree given by the angular momentum in the high energy regime. We also obtain a similar formula from

Tsunehide Kuroki; Toshihiro Matsuo

2008-01-01

387

Melt dumping in string stabilized ribbon growth  

DOEpatents

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.

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

1986-12-09

388

Quantum switching and quantum string matching  

Microsoft Academic Search

Applications of quantum string matching can be found in quantum signature scheme and quantum fingerprinting. The major benefit of these applications is computation complexity. Quantum Boolean circuits can check the equivalence function: all in puts are quantum digital state. However, it is difficult to verify quantum strings if all input qubits are quantum superposition state. Quantum switching could be reversible

Tien-Sheng Lin; Chin-Yung Lu; Sy-Yen Kuo

2010-01-01

389

Valleys in string foam suppress quantum coherence.  

National Technical Information Service (NTIS)

String contributions to the S matrix are derived relating in- and out-state density matrices that do not factorize as a product of S and S(sup t) matrices. They are associated with valley trajectories between topological defects on the string world sheet,...

J. Ellis D. V. Nanopoulos N. E. Mavromatos

1993-01-01

390

Solid-state-laser-rod holder  

DOEpatents

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.

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

1981-08-11

391

49 CFR 236.793 - Rod, lock.  

Code of Federal Regulations, 2013 CFR

...APPLIANCES Definitions § 236.793 Rod, lock. A rod, attached to the front rod or lug of a switch, movable-point frog or derail, through which a locking plunger may extend when the switch points or derail are in the normal or reverse...

2013-10-01

392

Fuel followed control rod installation at AFRRI  

SciTech Connect

Fuel Followed Control Rods (FFCRs) were installed at the Armed Forces Radiobiology Research Institute's 1 MW TRIGA Reactor. The procedures for obtaining, shipping, and installing the FFCRs is described. As part of the FFCR installation, the transient rod drive was relocated. Core performance due to the addition of the fuel followed control rods is discussed. (author)

Moore, Mark; Owens, Chris; Forsbacka, Matt [Defense Nuclear Agency, Armed Forces Radiobiology Research Institute TRIGA Reactor (United States)

1992-07-01

393

Hydraulic Actuator for Ganged Control Rods  

NASA Technical Reports Server (NTRS)

Hydraulic actuator moves several nuclear-reactor control rods in unison. Electromagnetic pump pushes liquid lithium against ends of control rods, forcing them out of or into nuclear reactor. Color arrows show lithium flow for reactor startup and operation. Flow reversed for shutdown. Conceived for use aboard spacecraft, actuator principle applied to terrestrial hydraulic machinery involving motion of ganged rods.

Thompson, D. C.; Robey, R. M.

1986-01-01

394

Nuclear fuel-rod assembly support structure  

Microsoft Academic Search

A nuclear fuel rod assembly support structure has top and bottom end pieces, and a plurality of fuel rod spacer grids and control-rod guide tubes. It has top and bottom ends fastened to the top and bottom end pieces to hold these pieces interspaced. The guide tubes are inserted slidably through the openings in the spacer grids. It is necessary

Bezold

1978-01-01

395

Rod pathways: the importance of seeing nothing  

Microsoft Academic Search

Anatomical and physiological studies of the mammalian retina have revealed two primary pathways available for the transmission of rod signals to the ganglion cells: one via ON rod bipolars, amacrine II cells, and ON and OFF cone bipolars, which is exquisitely designed for the transmission of single-photon absorption events; and a second via rod–cone gap junctions, and ON and OFF

Lindsay T. Sharpe; Andrew Stockman

1999-01-01

396

CMB temperature trispectrum of cosmic strings  

SciTech Connect

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

Hindmarsh, Mark; Ringeval, Christophe; Suyama, Teruaki [Department of Physics and Astronomy, University of Sussex, Brighton, BN19QH (United Kingdom); Theoretical and Mathematical Physics Group, Centre for Particle Physics and Phenomenology, Louvain University, 2 Chemin du Cyclotron, 1348 Louvain-la-Neuve (Belgium)

2010-03-15

397

Stretched strings in noncommutative field theory  

SciTech Connect

Motivated by recent discussions of IR-UV mixing in noncommutative field theories, we perform a detailed analysis of the nonplanar amplitudes of the bosonic open string in the presence of an external B field at the one-loop level. We carefully isolate, at the string theory level, the contribution which is responsible for the IR-UV behavior in the field theory limit. We show that it is a pure open string effect by deriving it from the factorization of the one-loop amplitude into the disk amplitudes of intermediate open string insertions. We suggest that it is natural to understand IR-UV mixing as the creation of intermediate ''stretched strings.'' (c) 2000 The American Physical Society.

Liu, Hong [New High Energy Theory Center, Rutgers University, 126 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States)] [New High Energy Theory Center, Rutgers University, 126 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States); Michelson, Jeremy [New High Energy Theory Center, Rutgers University, 126 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States)] [New High Energy Theory Center, Rutgers University, 126 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States)

2000-09-15

398

Effects of friction on cosmic strings  

NASA Astrophysics Data System (ADS)

We study the evolution of cosmic strings taking into account the frictional force due to the surrounding radiation. We consider small perturbations on straight strings, oscillation of circular loops, and small perturbations on circular loops. For straight strings, friction exponentially suppresses perturbations whose comoving scale crosses the horizon before the cosmological time t*~?-2 (in Planck units), where ? is the string tension. Loops with a size much smaller than t* will be approximately circular at the time when they start the relativistic collapse. We investigate the possibility that such loops will form black holes. We find that the number of black holes which is formed through this process is well below present observational limits, so this does not give any lower or upper bounds on ?. We also consider the case of straight strings attached to walls and circular holes that can spontaneously nucleate on metastable domain walls.

Garriga, Jaume; Sakellariadou, Maria

1993-09-01

399

Cosmic (p,q,r) strings  

NASA Astrophysics Data System (ADS)

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

Jackson, Mark G.

2007-04-01

400

CMB temperature trispectrum of cosmic strings  

NASA Astrophysics Data System (ADS)

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

Hindmarsh, Mark; Ringeval, Christophe; Suyama, Teruaki

2010-03-01

401

Vibration monitoring system for drill string  

SciTech Connect

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

Wassell, M.E.

1993-07-13

402

Cosmic strings and chronology protection  

NASA Astrophysics Data System (ADS)

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

Grant, James D. E.

1993-03-01

403

Trampling, defoliation and physiological integration affect growth, morphological and mechanical properties of a root-suckering clonal tree  

PubMed Central

Background and Aims Grazing is a complex process involving the simultaneous occurrence of both trampling and defoliation. Clonal plants are a common feature of heavily grazed ecosystems where large herbivores inflict the simultaneous pressures of trampling and defoliation on the vegetation. We test the hypothesis that physiological integration (resource sharing between interconnected ramets) may help plants to deal with the interactive effects of trampling and defoliation. Methods In a field study, small and large ramets of the root-suckering clonal tree Populus simonii were subjected to two levels of trampling and defoliation, while connected or disconnected to other ramets. Plant responses were quantified via survival, growth, morphological and stem mechanical traits. Key Results Disconnection and trampling increased mortality, especially in small ramets. Trampling increased stem length, basal diameter, fibrous root mass, stem stiffness and resistance to deflection in connected ramets, but decreased them in disconnected ones. Trampling decreased vertical height more in disconnected than in connected ramets, and reduced stem mass in disconnected ramets but not in connected ramets. Defoliation reduced basal diameter, leaf mass, stem mass and leaf area ratio, but did not interact with trampling or disconnection. Conclusions Although clonal integration did not influence defoliation response, it did alleviate the effects of trampling. We suggest that by facilitating resource transport between ramets, clonal integration compensates for trampling-induced damage to fine roots.

Xu, Liang; Yu, Fei-Hai; van Drunen, Elles; Schieving, Feike; Dong, Ming; Anten, Niels P. R.

2012-01-01

404

Spermiogenesis and spermatozoon ultrastructure of Hunterella nodulosa (Cestoda: Caryophyllidea), a monozoic parasite of suckers (Catostomidae) in North America.  

PubMed

Spermiogenesis and ultrastructure of mature spermatozoon of the caryophyllidean cestode Hunterella nodulosa, a parasite of suckers (Catostomidae), have been studied by transmission electron microscopy. This monozoic tapeworm is unique in its mode of attachment and represents the second North American species studied. The process of spermiogenesis of H. nodulosa follows the general pattern already described in other caryophyllideans. The most characteristic feature is the presence of a slight rotation of the flagellar bud, which seems to be a typical character of spermiogenesis in this cestode group. The mature spermatozoon of H. nodulosa is characterized by the presence of one axoneme of 9 + "1" type of the trepaxonematan flatworms surrounded by a semi-arc of cortical microtubules in its anterior extremity, parallel nucleus and cortical microtubules arranged in a parallel pattern, which corresponds to the Type III pattern of cestode spermatozoa according to Levron et al. (2010). Comparison of the present data with those available for other caryophyllideans did not reveal substantial differences, even though they belong to different families, infect different hosts (catostomid, cyprinid and siluriform fishes) and occur in distant zoogeographical regions. This indicates uniformity of the process of sperm formation and spermatozoon ultrastructure in one of the evolutionarily most ancient groups of tapeworms. PMID:23136798

Yoneva, Aneta; Levron, Celine; Oros, Mikulás; Orosová, Martina; Scholz, Tomás

2012-09-01

405

The strings connection: MSSM-like models from strings  

NASA Astrophysics Data System (ADS)

String theory constructions towards the MSSM allow us to identify some general properties that could be relevant for tests at the LHC. They originate from the geometric structure of compactification and the location of fields in extra-dimensional space. Within the framework of the heterotic MiniLandscape we extract some generic lessons for supersymmetric model building. Among them is a specific pattern of SUSY breakdown based on mirage mediation and remnants of extended supersymmetry. This leads to a split spectrum with heavy scalars of the first two families of quarks and leptons and suppressed masses for gauginos, top partners and Higgs bosons. The models exhibit some specific form of hidden supersymmetry consistent with the high mass of the Higgs boson and all presently available experimental constraints. The most compelling picture is based on precision gauge coupling unification that might be in the kinematic reach of the LHC.

Nilles, Hans Peter

2014-05-01

406

Fuel rod assembly to manifold attachment  

DOEpatents

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

Donck, Harry A. (San Diego, CA); Veca, Anthony R. (San Diego, CA); Snyder, Jr., Harold J. (San Diego, CA)

1980-01-01

407

Polymeric optical mixing rod coupler  

Microsoft Academic Search

Optical mixing rod couplers have been fabricated using extruded plastic tubing filled with optically transparent casting resins to form a waveguide-type mixing region. Asymmetric (1×19) splitter\\/combiners with plastic fiber and plastic-clad silica fiber pigtails have been made with efficiencies greater than 60% and power uniformities within 1-dB standard deviation. Tested as a combiner, the coupler had an average loss of

G. J. Grimes

1990-01-01

408

Stuck fuel rod capping sleeve  

SciTech Connect

A stuck fuel rod capping sleeve is described comprising: an inner cylindrical sleeve made of low work hardening, highly ductile material and having tapered and split end portions; an outer cylindrical sleeve made of moderately ductile material and mounted on the inner cylindrical sleeve, the outer cylindrical sleeve having threads located at each end thereof; and a locking sleeve threaded on each end of the outer cylindrical sleeve, each locking sleeve having threads located on its exterior surface.

Gorscak, D.A.; Nilsen, R.J.; Maringo, J.J.

1988-03-22

409

Dynamic analysis of slender rods  

SciTech Connect

A new three-dimensional finite element model of an inextensible elastic rod with equal principal stiffnesses is presented. The model permits large deflections and finite rotations and accounts for tension variation along its length. Its use in static analysis is described and a time integration method for dynamic analysis is developed. Accuracy of the spatial discretization and stability of the time integration method are demonstrated by comparison of numerical results with exact solutions for certain nonlinear problems.

Garrett, D.L.

1982-12-01

410

A Review on Tachyon Condensation in Open String Field Theories  

Microsoft Academic Search

We review the recent studies of tachyon condensation in string field theory. After introducing the open string field theory both for bosonic string and for superstring, we use them to examine the conjecture that the unstable configurations of the D-brane will decay into the `closed string vacuum' through the tachyon condensation. And we describe the attemps to construct a lower

Kazuki Ohmori

2001-01-01

411

Theoretical and Empirical Comparisons of Approximate String Matching Algorithms  

Microsoft Academic Search

We study in depth a model of non-exact pattern matching based on edit distance, which is the minimum number of substitutions, insertions, and deletions needed to transform one string of symbols to another. More precisely, the k differences approximate string matching problem specifies a text string of length n, a pattern string of length m, the number k of differences

William I. Chang; Jordan Lampe

1992-01-01

412

Worldsheet factorization for twistor-strings  

NASA Astrophysics Data System (ADS)

We study the multiparticle factorization properties of two worldsheet theories which — at tree-level — describe the scattering of massless particles in four dimensions: the Berkovits-Witten twistor-string for = 4 super-Yang-Mills coupled to = 4 conformal supergravity, and the Skinner twistor-string for = 8 supergravity. By considering these string-like theories, we can study factorization at the level of the worldsheet before any Wick contractions or integrals have been performed; this is much simpler than considering the factorization properties of the amplitudes themselves. In Skinner's twistor-string this entails the addition of worldsheet gravity as well as a formalism that represents all external states in a manifestly symmetric way, which we develop explicitly at genus zero. We confirm that the scattering amplitudes of Skinner's theory, as well as the gauge theory amplitudes for the planar sector of the Berkovits-Witten theory, factorize appropriately at genus zero. In the non-planar sector, we find behavior indicative of conformal gravity in the Berkovits-Witten twistor-string. We contrast factorization in twistor-strings with the story in ordinary string theory, and also make some remarks on higher genus factorization and disconnected prescriptions.

Adamo, Tim

2014-04-01

413

CMB temperature bispectrum induced by cosmic strings  

NASA Astrophysics Data System (ADS)

The cosmic microwave background (CMB) bispectrum of the temperature anisotropies induced by a network of cosmic strings is derived for small angular scales, under the assumption that the principal cause of temperature fluctuations is the Gott-Kaiser-Stebbins effect. We provide analytical expressions for all isosceles triangle configurations in Fourier space. Their overall amplitude is amplified as the inverse cube of the angle and diverges for flat triangles. The isosceles configurations generically lead to a negative bispectrum with a power-law decay ?-6 for large multipole ?. However, collapsed triangles are found to be associated with a positive bispectrum whereas the squeezed triangles still exhibit negative values. We then compare our analytical estimates to a direct computation of the bispectrum from a set of 300 statistically independent temperature maps obtained from Nambu-Goto cosmic string simulations in a Friedmann-Lemaître-Robertson-Walker universe. We find good agreement for the overall amplitude, the power-law behavior, and the angle dependency of the various triangle configurations. At ?˜500 the cosmic string Gott-Kaiser-Stebbins effect contributes approximately the same equilateral CMB bispectrum amplitude as an inflationary model with |fNLloc|?103, if the strings contribute about 10% of the temperature power spectrum at ?=10. Current bounds on fNL are not derived using cosmic string bispectrum templates, and so our fNL estimate cannot be used to derive bounds on strings. However it does suggest that string bispectrum templates should be included in the search of CMB non-Gaussianities.

Hindmarsh, Mark; Ringeval, Christophe; Suyama, Teruaki

2009-10-01

414

B-modes from cosmic strings  

SciTech Connect

Detecting the parity-odd, or B-mode, polarization pattern in the cosmic microwave background radiation due to primordial gravity waves is considered to be the final observational key to confirming the inflationary paradigm. The search for viable models of inflation from particle physics and string theory has (re)discovered another source for B-modes: cosmic strings. Strings naturally generate as much vector-mode perturbation as they do scalar, producing B-mode polarization with a spectrum distinct from that expected from inflation itself. In a large set of models, B-modes arising from cosmic strings are more prominent than those expected from primordial gravity waves. In light of this, we study the physical underpinnings of string-sourced B-modes and the model dependence of the amplitude and shape of the C{sub l}{sup BB} power spectrum. Observational detection of a string-sourced B-mode spectrum would be a direct probe of post-inflationary physics near the grand unified theory (GUT) scale. Conversely, nondetection would put an upper limit on a possible cosmic string tension of G{mu} < or approx. 10{sup -7} within the next three years.

Pogosian, Levon; Wyman, Mark [Department of Physics, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6 (Canada); Perimeter Institute for Theoretical Physics, 31 Caroline St. N, Waterloo, ON, L6H 2A4 (Canada)

2008-04-15

415

Strings next to and inside black holes  

SciTech Connect

The classical string equations of motion and constraints are solved near the horizon and near the singularity of a Schwarzschild black hole. In a conformal gauge such that {tau}=0 ({tau}=world sheet time coordinate) corresponds to the horizon ({ital r}=1) or to the black hole singularity ({ital r}=0), the string coordinates express in power series in {tau} near the horizon and in power series in {tau}{sup 1/5} around {ital r}=0. We compute the string invariant size and the string energy-momentum tensor. Near the horizon both are finite and analytic. Near the black hole singularity, the string size, the string energy, and the transverse pressures (in the angular directions) tend to infinity as {ital r}{sup {minus}1}. To leading order near {ital r}=0, the string behaves as two-dimensional radiation. These two spatial dimensions are describing the {ital S}{sup 2} sphere in the Schwarzschild manifold. {copyright} {ital 1996 The American Physical Society.}

de Vega, H.J. [Laboratoire de Physique Theorique et Hautes Energies, Universites Paris VI-VII - Laboratoire associe au CNRS No. 280, Tour 16, 1er. et., 4, Place Jussieu, 75252 Paris Cedex 05 (France)] [Laboratoire de Physique Theorique et Hautes Energies, Universites Paris VI-VII - Laboratoire associe au CNRS No. 280, Tour 16, 1er. et., 4, Place Jussieu, 75252 Paris Cedex 05 (France); Egusquiza, I.L. [Fisika Teorikoaren Saila, Euskal Herriko Unibertsitatea, 644 P.K. - 48080 Bilbao (Spain)] [Fisika Teorikoaren Saila, Euskal Herriko Unibertsitatea, 644 P.K. - 48080 Bilbao (Spain)

1996-03-01

416

Strings and their compactification from the particle viewpoint  

SciTech Connect

A series of four lectures is given which deals with the particle formulation of string theory. An introductory lecture is given on where the idea of strings comes from and what strings are. An introduction is given to simple Lie algebras and their representations. Compactified strings and the heterotic theories are discussed, showing how infinite-dimensional Kac-Moody affine algebras can be spectrum generating algebras in (open) string theories. The spectrum of excited states of the heterotic string is examined, and comments are made on representations of affine algebras. Some aspects are shown of the algebraic structure of compactified closed bosonic strings. (LEW)

Slansky, R.

1986-01-01

417

Charged rotating dilaton black strings  

SciTech Connect

In this paper we, first, present a class of charged rotating solutions in four-dimensional Einstein-Maxwell-dilaton gravity with zero and Liouville-type potentials. We find that these solutions can present a black hole/string with two regular horizons, an extreme black hole or a naked singularity provided the parameters of the solutions are chosen suitable. We also compute the conserved and thermodynamic quantities, and show that they satisfy the first law of thermodynamics. Second, we obtain the (n+1)-dimensional rotating solutions in Einstein-dilaton gravity with Liouville-type potential. We find that these solutions can present black branes, naked singularities or spacetimes with cosmological horizon if one chooses the parameters of the solutions correctly. Again, we find that the thermodynamic quantities of these solutions satisfy the first law of thermodynamics.

Dehghani, M.H. [Physics Department and Biruni Observatory, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Research Institute for Astrophysics and Astronomy of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Farhangkhah, N. [Physics Department and Biruni Observatory, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)

2005-02-15

418

Cosmic string induced peculiar velocities  

NASA Technical Reports Server (NTRS)

This paper considers the scenario of a flat universe with a network of heavy cosmic strings as the primordial fluctuation spectrum. The joint probability of finding streaming velocities of at least 600 km/s on large scales and local peculiar velocities of less than 800 km/s is calculated. It is shown how the effects of loops breaking up and being born with a spectrum of sizes can be estimated. It is found that to obtain large-scale streaming velocities of at least 600 km/s, it is necessary that either a large value for beta G mu exist or the effect of loop fissioning and production details be considerable.

Van Dalen, Anthony; Schramm, David N.

1988-01-01

419

Graviton Spectra in String Cosmology  

SciTech Connect

We propose to uncover the signature of a stringy era in the primordial Universe by searching for a prominent peak in the relic graviton spectrum. This feature, which in our specific model terminates an {omega}{sup 3} increase and initiates an {omega}{sup {minus}7} decrease, is induced during the so far overlooked bounce of the scale factor between the collapsing deflationary era (or pre{endash}big bang) and the expanding inflationary era (or post{endash}big bang). The frequency and the intensity of the peak may likely fall in the realm of the new generation of interferometric detectors. The existence of a peak, at variance with ordinarily monotonic graviton spectra, would therefore offer strong support to string cosmology. {copyright} {ital 1997} {ital The American Physical Society}

Galluccio, M.; Occhionero, F. [Osservatorio Astronomico di Roma, Via del Parco Mellini 84, 00136 Roma (Italy)] [Osservatorio Astronomico di Roma, Via del Parco Mellini 84, 00136 Roma (Italy); Litterio, M. [Istituto Astronomico dell`Universita La Sapienza, Via G. M. Lancisi 29, 00186 Roma (Italy)] [Istituto Astronomico dell`Universita La Sapienza, Via G. M. Lancisi 29, 00186 Roma (Italy)

1997-08-01

420

Apparatus in a drill string  

DOEpatents

An apparatus in a drill string comprises an internally upset drill pipe. The drill pipe comprises a first end, a second end, and an elongate tube intermediate the first and second ends. The elongate tube and the ends comprising a continuous an inside surface with a plurality of diameters. A conformable spirally welded metal tube is disposed within the drill pipe intermediate the ends thereof and terminating adjacent to the ends of the drill pipe. The conformable metal tube substantially conforms to the continuous inside surface of the metal tube. The metal tube may comprise a non-uniform section which is expanded to conform to the inside surface of the drill pipe. The non-uniform section may comprise protrusions selected from the group consisting of convolutions, corrugations, flutes, and dimples. The non-uniform section extends generally longitudinally along the length of the tube.

Hall, David R. (Provo, UT); Dahlgren, Scott (Alpine, UT); Hall, Jr., Tracy H. (Provo, UT); Fox, Joe (Lehi, UT); Pixton, David S. (Provo, UT)

2007-07-17

421

Relational String Verification Using Multi-track Automata  

NASA Astrophysics Data System (ADS)

Verification of string manipulation operations is a crucial problem in computer security. In this paper, we present a new relational string verification technique based on multi-track automata. Our approach is capable of verifying properties that depend on relations among string variables. This enables us to prove that vulnerabilities that result from improper string manipulation do not exist in a given program. Our main contributions in this paper can be summarized as follows: (1) We formally characterize the string verification problem as the reachability analysis of string systems and show decidability/undecidability results for several string analysis problems. (2) We develop a sound symbolic analysis technique for string verification that over-approximates the reachable states of a given string system using multi-track automata and summarization. (3) We evaluate the presented techniques with respect to several string analysis benchmarks extracted from real web applications.

Yu, Fang; Bultan, Tevfik; Ibarra, Oscar H.

422

Current discontinuities on superconducting cosmic strings  

SciTech Connect

The propagation of current perturbations on superconducting cosmic strings is considered. The conditions for the existence of discontinuities similar to shock waves have been found. The formulas relating the string parameters and the discontinuity propagation speed are derived. The current growth law in a shock wave is deduced. The propagation speeds of shock waves with arbitrary amplitudes are calculated. The reason why there are no shock waves in the case of time-like currents (in the 'electric' regime) is explained; this is attributable to the shock wave instability with respect to perturbations of the string world sheet.

Troyan, E., E-mail: et@iaaru.astronautiko.org; Vlasov, Yu. V. [Moscow Institute of Physics and Technology (Russian Federation)

2011-07-15

423

The String and the Cosmic Bounce  

NASA Astrophysics Data System (ADS)

String theory introduces a new fundamental scale (the string length) that is expected to regularize the singularities of classical general relativity. In a cosmological context, the Big Bang is no longer regarded as the beginning of time, but just a transition between a Pre-Big Bang collapse phase and the current expansion. We will review old and recent attempts to build consistent bouncing cosmologies inspired to string theories, discussing their solved and unsolved problems, focussing on the observables that may distinguish them from standard inflationary scenarios.

Bozza, V.

2014-04-01

424

Improved Tennis Racquets Have Tapered Strings  

NASA Technical Reports Server (NTRS)

Design concept for better performing tennis racquet. Essence of concept to taper strings in such way as to shift center of percussion (also called "sweet spot") toward the toe (outer end of racquet, farthest from player's hand). In addition to increasing power on serves, also improves player's control and feel of racquet in player's hand. Racquet less likely to twist in player's hand on off-center shots. Important element of better feel is better absorption of vibrations; especially for players having chronic arm problems. String material nylon, animal gut, or other naturally or artifically spun threads. String can be attached to conventional racquet frame.

Noever, David A.

1995-01-01

425

String resonances at the Large Hadron Collider  

SciTech Connect

The Large Hadron Collider promises to discover new physics beyond the standard model. An exciting possibility is the formation of string resonances at the TeV scale. In this article, we show how string resonances may be detected at the LHC in the pp{yields}{gamma}+jet channel. Our study is based on event-shape variables, missing energy and momentum, maximum transverse momentum of photons and dijet invariant mass. These observables provide interesting signatures which enable us to discriminate string events from the standard model background.

Roy, Arunava; Cavaglia, Marco [Department of Physics and Astronomy, University of Mississippi, University, Mississippi 38677-1848 (United States)

2009-07-01

426

Cosmic string lensing and closed timelike curves  

NASA Astrophysics Data System (ADS)

In an analysis of the gravitational lensing by two relativistic cosmic strings, we argue that the formation of closed timelike curves proposed by Gott is unstable in the presence of particles (e.g. the cosmic microwave background radiation). Because of the attractorlike behavior of the closed timelike curve, we argue that this instability is very generic. A single graviton or photon in the vicinity, no matter how soft, is sufficient to bend the strings and prevent the formation of closed timelike curves. We also show that the gravitational lensing due to a moving cosmic string is enhanced by its motion, not suppressed.

Shlaer, Benjamin; Tye, S.-H. Henry

2005-08-01

427

Cosmic strings and the microwave sky. I - Anisotropy from moving strings  

NASA Technical Reports Server (NTRS)

A method is developed for calculating the component of the microwave anisotropy around cosmic string loops due to their rapidly changing gravitational fields. The method is only valid for impact parameters from the string much smaller than the horizon size at the time the photon passes the string. The method makes it possible to calculate the temperature pattern around arbitrary string configurations numerically in terms of one-dimensional integrals. This method is applied to temperature jump across a string, confirming and extending previous work. It is also applied to cusps and kinks on strings, and to determining the temperature pattern far from a strong loop. The temperature pattern around a few loop configurations is explicitly calculated. Comparisons with the work of Brandenberger et al. (1986) indicates that they have overestimated the MBR anisotropy from gravitational radiation emitted from loops.

Stebbins, Albert

1988-01-01

428

Open-closed string duality at tree level.  

PubMed

We study the decay of unstable D-branes in string theory in the presence of an electric field, and show that the classical open string theory results for various properties of the final state agree with the properties of closed string states into which the system is expected to decay. This suggests a duality between tree level open string theory on unstable D-branes and closed strings at high density. PMID:14611274

Sen, Ashoke

2003-10-31

429

The current status of observational constraints on cosmic strings  

SciTech Connect

The observational restrictions on the cosmic string scenario for the formation of large scale structure are evaluated. this restrictions are due to the spectrum of gravitational radiation emitted by oscillating string loops, anisotropies in the cosmic microwave background caused by the strings, and evaporating black holes formed from collapsed cosmic string loops. It is shown that the only free parameter of the scenario, the cosmic string mass-per-unit-length, {mu}, is severely restricted.

Caldwell, R.R.

1993-10-01

430

Non-abelian Ramond-Neveu-Schwarz string theory  

Microsoft Academic Search

We newly construct a world-sheet matrix string theory described by two-dimensional supergravity coupled to supersymmetric Yang-Mills fields where the string coordinates are non-commuting matrices in the gauge group U(N). We show that our string theory has a free string limit where it becomes N-copies of usual Ramond-Neveu-Schwarz strings and can be described by the orbifold conformal field theory being second

Hyun Seok Yang; Inbo Kim; Bum-Hoon Lee

1999-01-01

431

BiP prevents rod opsin aggregation  

PubMed Central

Mutations in rod opsin—the light-sensitive protein of rod cells—cause retinitis pigmentosa. Many rod opsin mutations lead to protein misfolding, and therefore it is important to understand the role of molecular chaperones in rod opsin biogenesis. We show that BiP (HSPA5) prevents the aggregation of rod opsin. Cleavage of BiP with the subtilase cytotoxin SubAB results in endoplasmic reticulum (ER) retention and ubiquitylation of wild-type (WT) rod opsin (WT–green fluorescent protein [GFP]) at the ER. Fluorescence recovery after photobleaching reveals that WT-GFP is usually mobile in the ER. By contrast, depletion of BiP activity by treatment with SubAB or coexpression of a BiP ATPase mutant, BiP(T37G), decreases WT-GFP mobility to below that of the misfolding P23H mutant of rod opsin (P23H-GFP), which is retained in the ER and can form cytoplasmic ubiquitylated inclusions. SubAB treatment of P23H-GFP–expressing cells decreases the mobility of the mutant protein further and leads to ubiquitylation throughout the ER. Of interest, BiP overexpression increases the mobility of P23H-GFP, suggesting that it can reduce mutant rod opsin aggregation. Therefore inhibition of BiP function results in aggregation of rod opsin in the ER, which suggests that BiP is important for maintaining the solubility of rod opsin in the ER.

Athanasiou, Dimitra; Kosmaoglou, Maria; Kanuga, Naheed; Novoselov, Sergey S.; Paton, Adrienne W.; Paton, James C.; Chapple, J. Paul; Cheetham, Michael E.

2012-01-01

432

Exact cosmological solutions of 4D string gravity in the string frame  

NASA Astrophysics Data System (ADS)

We have discussed a particular class of exact cosmological solutions of the 4-dimensional low energy string gravity in the string frame. In the vacuum without matter and the 2-form fields, the exact cosmological solutions always give monotonically shrinking universes if the dilaton field is not a constant. However, in the presence of the 2-form fields and/or the radiation-like fluid in the string frame, the exact cosmological solutions show a minimum size of the universe in the evolution, but with an initial cosmological curvature singularity in the string frame.

Yoon, Yongsung

2014-05-01

433

Simulation studies of self-assembly of end-tethered nanorods in solution and role of rod aspect ratio and tether length  

NASA Astrophysics Data System (ADS)

We present temperature versus concentration phase diagrams for ``shape amphiphiles'' comprised of tethered moderate and low aspect ratio rods. Simulations of moderate aspect ratio rods (first reported by Horsch et al. [Phys. Rev. Lett. 95, 056105 (2005)]) predict their self-assembly into spherical micelles with bcc order, long micelles with nematic order, a racemic mixture of hexagonally ordered chiral cylinders, two perforated phases: one with tetragonal order and one with hexagonal order, and a smectic C lamellar phase. In contrast, we predict here that small aspect ratio tethered rods self-assemble into bcc ordered spherical micelles, hexagonally ordered cylinders, and a smectic C lamellar phase. We compare and contrast the phases obtained for the two aspect ratios and examine in further detail several unusual phases. Our simulations also reveal that for moderate aspect ratio rods there is a tendency toward phases with decreasing interfacial curvature with decreasing coil size, including a double gyroid phase. In addition, we investigate the role of tether length on the assembled structures. Our results are applicable to short rod-coil block copolymers and rodlike nanoparticles with polymer tethers, and to colloidal building blocks comprised of a flexible string of colloids tethered to a rigid string of colloids, with the interactions scaled appropriately.

Horsch, Mark A.; Zhang, Zhenli; Glotzer, Sharon C.

2006-11-01

434

Supergrassmannians, Super tau-Functions and Strings.  

National Technical Information Service (NTIS)

Recently, infinite-dimensional grassmannians and their supergeneralizations were used to study conformal two-dimensional fields and strings. In particular, the super Mumford form (holomorphic square root from the superstring measure on moduli space) was e...

S. N. Dolgikh A. S. Schwarz

1989-01-01

435

Cosmological solutions of supercritical string theory  

SciTech Connect

We study quintessence-driven, spatially flat, expanding Friedmann-Robertson-Walker cosmologies that arise naturally from string theory formulated in a supercritical number of spacetime dimensions. The tree-level potential of the string theory produces an equation of state at the threshold between accelerating and decelerating cosmologies, and the resulting spacetime is globally conformally equivalent to Minkowski space. We demonstrate that exact solutions exist with a condensate of the closed-string tachyon, the simplest of which is a Liouville wall moving at the speed of light. We rely on the existence of this solution to derive constraints on the couplings of the tachyon to the dilaton and metric in the string theory effective action. In particular, we show that the tachyon dependence of the Einstein term must be nontrivial.

Hellerman, Simeon; Swanson, Ian [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540 (United States)

2008-06-15

436

de Sitter Vacua in String Theory.  

National Technical Information Service (NTIS)

We outline the construction of metastable de Sitter vacua of type IIB string theory. Our starting point is highly warped IIB compactifications with nontrivial NS and RR three-form fluxes. By incorporating known corrections to the superpotential from Eucli...

S. Kachru R. Kallosh A. Linde S. P. Trivedi

2003-01-01

437

Effective string theory and QCD scattering amplitudes  

SciTech Connect

QCD string is formed at distances larger than the confinement scale and can be described by the Polchinski-Strominger effective string theory with a nonpolynomial action, which has nevertheless a well-defined semiclassical expansion around a long-string ground state. We utilize modern ideas about the Wilson-loop/scattering-amplitude duality to calculate scattering amplitudes and show that the expansion parameter in the effective string theory is small in the Regge kinematical regime. For the amplitudes we obtain the Regge behavior with a linear trajectory of the intercept (d-2)/24 in d dimensions, which is computed semiclassically as a momentum-space Luescher term, and discuss an application to meson scattering amplitudes in QCD.

Makeenko, Yuri [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation)

2011-01-15

438

The pomeron in closed bosonic string theory  

SciTech Connect

We compute the couplings of the pomeron to the first few mass levels of closed bosonic string states in flat space. We recognize the deviation from the linearity of the Regge trajectories in a five dimensional anti De Sitter background.

Fazio, A. R. [Departamento de fisica, Universidad Nacional de Colombia, Ciudad Universitaria, Bogota D.C. (Colombia)

2010-12-22

439

Beads + String = Atoms You Can See.  

ERIC Educational Resources Information Center

Presents hands-on activities that give students a head start in learning the vocabulary and basic theory involved in understanding atomic structure. Uses beads to represent protons, neutrons, and electrons and string to represent orbitals. (DDR)

Hermann, Christine K. F.

1998-01-01

440

Electron strings in solids with narrow bands  

Microsoft Academic Search

Electronic phase separation may arise due to electron–phonon interactions. In polar materials with a narrow band this polarization effect may lead to the creation of electron strings, whose length depends on dielectric constants.

F. V. Kusmartsev

2000-01-01

441

Introduction to string and superstring theory II  

SciTech Connect

Conformal field theory is reviewed, then conformal invariance is used to rederive the basic results on the embedding dimensionality for bosonic and fermionic strings. The spectrum of the bosonic and the computation of scattering amplitudes are discussed. The formalism used is extended to clarify the origin of Yang-Mills gauge invariance in the open bosonic string theory. The question of the general-coordinate gauge invariance of string theory is addressed, presenting two disparate viewpoints on this question. A brief introduction is then given of the reduction from the idealized string theory in 10 extended dimensions to more realistic solutions in which all but 4 of these dimensions are compactified. The state of knowledge about the space-time supersymmetry of the superstring from the covariant viewpoint is outlined. An approach for identifying possible 6-dimensional spaces which might represent the form of the compact dimensions is discussed, and the orbifold scheme of compactification is presented. 77 refs., 18 figs. (LEW)

Peskin, M.E.

1987-03-01

442

Exact sum rules for inhomogeneous strings  

SciTech Connect

We derive explicit expressions for the sum rules of the eigenvalues of inhomogeneous strings with arbitrary density and with different boundary conditions. We show that the sum rule of order N may be obtained in terms of a diagrammatic expansion, with (N?1)!/2 independent diagrams. These sum rules are used to derive upper and lower bounds to the energy of the fundamental mode of an inhomogeneous string; we also show that it is possible to improve these approximations taking into account the asymptotic behavior of the spectrum and applying the Shanks transformation to the sequence of approximations obtained to the different orders. We discuss three applications of these results. -- Highlights: •We derive an explicit expression for the sum rules of an inhomogeneous string. •We obtain a diagrammatic representation for the sum rules of a given order. •We obtain precise bounds on the lowest eigenvalue of the string.

Amore, Paolo, E-mail: paolo.amore@gmail.com

2013-11-15

443

Cosmic strings in the real sky  

NASA Technical Reports Server (NTRS)

Observational strategies for finding effects associated with the gravitational lensing of distant objects by strings are discussed. In particular, a proposed search program at Steward Observatory to find chains of Galaxy image pairs is described.

Hogan, Craig J.

1987-01-01

444

Interactions of strings compactified on orbifolds  

SciTech Connect

It is very important to understand the process of string compactification before one can extract any reliable phenomenology. We consider an exactly solvable method of string compactification, in which the internal space is an orbifold. We compute various interaction amplitudes and describe how other amplitudes can be calculated. Multi-valued string variables are handled by formulating the amplitudes on covering spaces where they become single-valued. In the computation of the amplitudes, stretched string intermediate states give rise to expressions that are non-perturbative from the non-linear sigma model point of view. We also discuss, in the context of Z orbifold, the blowing up of the fixed points of an orbifold, to give rise to a Calabi-Yau manifold. The resulting Calabi-Yau manifold is shown to be non-perturbatively stable.

Hamidi, S.

1987-01-01

445

Tree Expansion Formalism for Generative String Rewriting.  

National Technical Information Service (NTIS)

An abstract generative string rewriting device is introduced for modeling such practical program generation and optimization tools as macro processors. The novel device is called a monosystem, and it differs from such classical abstract generative devices...

E. Lassila

2001-01-01

446

Well production control system  

SciTech Connect

An apparatus is described for monitoring the operation of a well pumping unit having a sucker-rod string and a power unit to reciprocate the rod string to produce fluid from an underground location, the apparatus having means for continuously compensating for a drift in characteristics of transducers used in monitoring the operation. The apparatus consists of: first transducer means for generating a signal representative of a load on the rod string; second transducer means for generating a signal representative of a position of the rod string; means for using the load signal and the position signal to generate a dynagraph of load vs. position of the sucker-rod string; means for calculating the area of the dynagraph; means for comparing the calculated area of the dynagraph with a predetermined set of area limits; means for comparing a maximum value of load signal against an acceptable maximum value of load signal; means for comparing a minimum value of load signal against an acceptable minimum value of load signal; means for combining current values of load signals with previous values of load signals to establish a selected value, and for combining a current value of rod position signal with previous values of rod position signals to establish a reference position of the rod string when the maximum value of the load, the minimum value of the load and the dynagraph area are each within acceptable limits; means for monitoring the load signal when the rod string reaches the reference position; and means for disabling the power unit when the value of the load signal exceeds the selected value at the reference position.

Chandra, R.S.; Quen, S.G.; Eineicher, D.E.; Lastra, J.E.

1986-06-10

447

Reflection of drill-string extensional waves at the bit-rock contact  

NASA Astrophysics Data System (ADS)

Downward propagating extensional waves are partially reflected at the bit-rock contact. The evaluation of the reflection coefficient is important to obtain while drilling information about the acoustic properties of the formations. The scope of this work is to estimate the bit-rock reflection coefficient, assuming a flat drill bit in perfect contact with the formation. Using the low-frequency approximation, which holds when the wavelength is much larger than the lateral dimensions of the borehole, the drill-string is assumed to be a laterally free rod, and the formation an homogeneous and isotropic medium. This work shows that the reflection coefficient of the extensional waves depends, along with the elastic properties of the formation, on the ratio of the cross sections of the drill-string and borehole. The impedance of the drilled rock can be calculated from the measured reflection coefficient, which is related to the amplitude of waves produced in the string and in the formation by a working drill-bit. copyright 2002 Acoustical Society of America.

Poletto, Flavio; Malusa, Massimo

2002-06-01

448

Cosmic string with a light massive neutrino  

NASA Technical Reports Server (NTRS)

We have estimated the power spectra of density fluctuations produced by cosmic strings with neutrino hot dark matter (HDM). Normalizing at 8/h Mpc, we find that the spectrum has more power on small scales than HDM + inflation, less than cold dark matter (CDM) + inflation, and significantly less the CDM + strings. With HDM, large wakes give significant contribution to the power on the galaxy scale and may give rise to large sheets of galaxies.

Albrecht, Andreas; Stebbins, Albert

1992-01-01

449

Tachyon condensation in string field theory  

Microsoft Academic Search

It has been conjectured that at a stationary point of the tachyon potential for the D-brane of bosonic string theory, the negative energy density exactly cancels the D-brane tension. We evaluate this tachyon potential by off-shell calculations in open string field theory. Surprisingly, the condensation of the tachyon mode alone into the stationary point of its cubic potential is found

Ashoke Sen; Barton Zwiebach

2000-01-01

450

Another Length Scale in String Theory?  

Microsoft Academic Search

We suggest that some of the remarkable results on stringy dynamics which have\\u000abeen found recently indicate the existence of another dynamical length scale in\\u000astring theory that, at weak coupling, is much shorter than the string scale.\\u000aThis additional scale corresponds to a mass $\\\\sim m_{\\\\rm s}\\/g_{\\\\rm s}$ where\\u000a$m_{\\\\rm s}$ is the square root of the string tension

Stephen H. Shenker

1995-01-01

451

Mirage pattern from the heterotic string  

SciTech Connect

We provide a simple example of dilaton stabilization in the framework of heterotic string theory. It requires a gaugino condensate and an uplifting sector similar to the one postulated in type IIB string theory. Its signature is a hybrid mediation of supersymmetry breakdown with a variant of a mirage pattern for the soft breaking terms. The setup is suited for the discussion of heterotic minimal supersymmetric standard model candidates.

Loewen, Valeri; Nilles, Hans Peter [Physikalisches Institut der Universitaet Bonn, Nussallee 12, 53115 Bonn (Germany)

2008-05-15

452

Electron string phenomenon: physics and use  

NASA Astrophysics Data System (ADS)

Electron string phenomenon arises as a result of phase transition of a state of multiply reflected electron beam to this new discovered state of one component electron plasma and can be easily observed in the reflex mode of EBIS operation. The transition goes via a strong instability, which causes considerable electron energy spread, which in its turn suppresses the instability. Electron string state is a stationary state of hot pure electron plasma, which is heated by injected electron beam and cooled because of electron loses. Electron string is quiet in broad regions of experimental parameters, so that it is used for confinement and ionization of positive ions by electron impact to highly charge states similar to electron beams in EBIS. Application of electron strings instead of electron beams for ion production allows to save about 99% of electric power of electron beam and simultaneously to improve reliability of an ion source considerably. The JINR EBIS `Krion-2' in the string mode of operation is used for production of N7+, Ar16+ and Fe24+ ion beams and their acceleration to relativistic energies on the facility of the JINR super conducting one turn injection synchrotron `Nuklotron'. The tubular electron string possibly can exist and it is under study now theoretically and experiments are prepared now. Estimations show that a Tubular Electron String Ion Source (TESIS) could have up to three orders of magnitude higher ion output then a Linear one (LESIS). In frames of nuclear astrophysics electron strings can be used for research of fusion nuclear reactions at low energies in conditions when both beam and target nuclei do not carry orbital electrons. The project NARITA — Nuclear Astrophysics Researches in an Ion Trap Apparatus is proposed. Polarization effects also can be studied.

Donets, Evgeny D.

2004-01-01

453

Direct integration of the topological string  

Microsoft Academic Search

We present a new method to solve the holomorphic anomaly equations governing the free energies of type B topological strings. The method is based on direct integration with respect to the non-holomorphic dependence of the amplitudes, and relies on the interplay between non-holomorphicity and modularity properties of the topological string amplitudes. We develop a formalism valid for any Calabi-Yau manifold

Thomas W. Grimm; Albrecht Klemm; Marcos Mariño; Marlene Weiss

2007-01-01

454

Cosmic String Detection via Microlensing of Stars  

Microsoft Academic Search

Cosmic superstrings are produced towards the end of the brane inflation. If\\u000athe string tension is low enough, loops tend to be relatively long-lived. The\\u000aresultant string network is expected to contain many loops which are smaller\\u000athan typical Galactic scales. Cosmic expansion damps the center of mass motion\\u000aof the loops which then cluster like cold dark matter. Loops

David F. Chernoff; S.-H. Henry

2007-01-01

455

Cosmic strings - A problem or a solution?  

NASA Technical Reports Server (NTRS)

The most fundamental issue in the theory of cosmic strings is addressed by means of Numerical Simulations: the existence of a scaling solution. The resolution of this question will determine whether cosmic strings can form the basis of an attractive theory of galaxy formation or prove to be a cosmological disaster like magnetic monopoles or domain walls. After a brief discussion of our numerical technique, results are presented which, though still preliminary, offer the best support to date of this scaling hypothesis.

Bennett, David P.; Bouchet, Francois R.

1988-01-01

456

String perturbation theory and effective Lagrangians  

SciTech Connect

We isolate logarithmic divergences from bosonic string amplitudes on a disc. These divergences are compared with 'tadpole' divergences in the effective field theory with a cosmological term, which also contains an effective potential for the dilation. Also, corrections to ..beta..-functions are compared with variations of the effective action. In both cases we find an inconsistency between the two. This is a serious problem which could undermine our ability to remove divergences from the bosonic string.

Klebanov, I.

1987-09-01

457

Closed String Tachyon Condensation on Twisted Circles  

Microsoft Academic Search

We study IIA\\/B string theory compactified on twisted circles. These models possess closed string tachyons and reduce to type-0B\\/A theory in a special limit. Using methods of gauged linear sigma models and mirror symmetry we construct a conformal field theory which interpolates between these models and flat space via an auxiliary Liouville direction. Interpreting motion in the Liouville direction as

Justin R. David; Michael Gutperle; Matthew Headrick; Shiraz Minwalla

2002-01-01

458

Mirror symmetry and the type II string  

Microsoft Academic Search

If $X$ and $Y$ are a mirror pair of Calabi--Yau threefolds, mirror symmetry\\u000ashould extend to an isomorphism between the type IIA string theory compactified\\u000aon $X$ and the type IIB string theory compactified on $Y$, with all\\u000anonperturbative effects included. We study the implications which this proposal\\u000ahas for the structure of the semiclassical moduli spaces of the compactified

David R. Morrison

1996-01-01

459

Rapidly moving cosmic strings and chronology protection  

NASA Astrophysics Data System (ADS)

Recently, Gott has provided a family of solutions of the Einstein equations describing pairs of parallel cosmic strings in motion. He has shown that if the strings' relative velocity is sufficiently high, there exist closed timelike curves (CTC's) in the spacetime. Here we show that if there are CTC's in such a solution, then every t=const hypersurface in the spacetime intersects CTC's. Therefore, these solutions do not contradict the chronology protection conjecture of Hawking.

Ori, Amos

1991-10-01

460

QCD and Gauge/String Duality  

NASA Astrophysics Data System (ADS)

We study the spectra of excited mesons with spins higher than one from gauge/string duality. We work with a model that is formulated on the basis of an intersecting D4/D8//line{D8}-system. The meson spectra are computed by making a semi-classical quantization of an open string that ends on the flavor D8-brane.We compare the results with experiments and find a good agreement.

Sakai, T.

2013-03-01

461

Semiclassical Strings and AdS\\/CFT  

Microsoft Academic Search

We discuss AdS\\/CFT duality in the sector of “semiclassical” string states with large quantum numbers. We review the coherent-state\\u000a effective action approach, in which similar 2d sigma model actions appear from the AdS5 × S5 string action and from the integrable spin chain Hamiltonian representing the N=4 super Yang-Mills dilatation operator. We\\u000a consider mostly the leading-order terms in the energies\\/anomalous

Arkady A. Tseytlin

2006-01-01

462

Quantum strings in quantum spin ice.  

PubMed

We study quantum spin ice in an external magnetic field applied along a <100> direction. When quantum spin fluctuations are weak, elementary excitations are quantum strings with monopoles at their ends manifested as multiple spin wave branches in the dynamical structure factor. Strong quantum fluctuations make the string tension negative and give rise to the deconfinement of monopoles. We discuss our results in the light of recent neutron scattering experiments in Yb2Ti2O7. PMID:23004322

Wan, Yuan; Tchernyshyov, Oleg

2012-06-15

463

Reactor control rod timing system. [LMFBR  

DOEpatents

A fluid driven jet-edge whistle timing system is described 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.

Wu, P.T.K.

1980-03-18

464

Action principle for subcritical string fields  

NASA Astrophysics Data System (ADS)

We consider the problem of constructing multiloop amplitudes for open string dual resonance models in space-time dimension D less than 26. These amplitudes are constructed so that open string unitarity is automatic. For general subcritical dimension, we show to remove redundant states by including an extra scalar world-sheet field (the free field incarnation of the Liouville degree of freedom) to make the BRST charge nilpotent, and the constructing a vertex function invariant under this modified charge. We prove the existence and uniqueness of this modified vertex for D<25. Although explicit calculations beyond one loop are very difficult, the duality properties are manifest. Our results are summarized by giving a Witten style action for open subcritical string fields. For the case D = 25, there are actually two solutions for a BRST invariant vertex function. The simplest does not lead to the subcritical dual loop amplitudes, because some of the redundant states still circulate the loops. However, in this case the scalar degree of freedom can be interpreted as a 26th coordinate, but with Dirichlet conditions on the open string. This is just a version of the critical string. The other solution has all redundant states removed and corresponds to the true subcritical dual model for D = 25. We consider, with partial success, the implications of this work for the interactions of subcritical closed strings.

Preitschopf, Christian R.; Thorn, Charles B.

1991-01-01

465

Spinning strings as small black rings  

NASA Astrophysics Data System (ADS)

Certain supersymmetric elementary string states with spin can be viewed as small black rings whose horizon has the topology of S1 × Sd-3 in a d-dimensional string theory. By analyzing the singular black ring solution in the supergravity approximation, and using various symmetries of the ?' corrected effective action we argue that the Bekenstein-Hawking-Wald entropy of the black string solution in the full string theory agrees with the statistical entropy of the same system up to an overall normalization constant. While the normalization constant cannot be determined by the symmetry principles alone, it can be related to a similar normalization constant that appears in the expression for small black holes without angular momentum in one less dimension. Thus agreement between statistical and macroscopic entropy of (d - 1)-dimensional non-rotating elementary string states would imply a similar agreement for a d-dimensional elementary string state with spin. Our analysis also determines the structure of the near horizon geometry and provides us with a geometric derivation of the Regge bound. These studies give further evidence that a ring-like horizon is formed when large angular momentum is added to a small black hole.

Dabholkar, Atish; Iqubal, Ashik; Iizuka, Norihiro; Sen, Ashoke; Shigemori, Masaki

2007-04-01

466

Unwinding the von Willebrand factor strings puzzle.  

PubMed

von Willebrand factor (VWF) is amongst others synthesized by endothelial cells and stored as ultra-large (UL) VWF multimers in Weibel-Palade bodies. Although UL-VWF is proteolysed by ADAMTS13 (a disintegrin-like and metalloprotease domain with thrombospondin type-1 motif, number 13) on secretion from endothelial cells, in vitro experiments in the absence of ADAMTS13 have demonstrated that a proportion of these UL-VWF multimers remain anchored to the activated endothelium. These multimers unravel, bind platelets, and wave in the direction of the flow. These so-called VWF "strings" have also been visualized in vivo, lining the lumen of activated mesenteric veins of Adamts13(-/-) mice. Various studies have demonstrated the extraordinary length of these VWF strings, the availability of their platelet binding and ADAMTS13 cleavage sites, and the possible nature of their endothelial attachment. VWF strings are also capable of tethering leukocytes and parasite-infected red blood cells. However, the majority of studies have been performed in the absence of ADAMTS13, a condition only experienced in thrombotic thrombocytopenic purpura. A normal functional role of VWF strings in healthy persons or in other disease pathologies remains unclear. In this review, we discuss some of the puzzling characteristics of VWF strings, and we debate whether the properties of VWF strings in the absence of ADAMTS13 might be relevant for understanding (patho)physiologic mechanisms. PMID:23093621

De Ceunynck, Karen; De Meyer, Simon F; Vanhoorelbeke, Karen

2013-01-10

467

High temperature control rod assembly  

DOEpatents

A high temperature nuclear control rod assembly comprises a plurality of substantially cylindrical segments flexibly joined together in succession by ball joints. The segments are made of a high temperature graphite or carbon-carbon composite. The segment includes a hollow cylindrical sleeve which has an opening for receiving neutron-absorbing material in the form of pellets or compacted rings. The sleeve has a threaded sleeve bore and outer threaded surface. A cylindrical support post has a threaded shaft at one end which is threadably engaged with the sleeve bore to rigidly couple the support post to the sleeve. The other end of the post is formed with a ball portion. A hollow cylindrical collar has an inner threaded surface engageable with the outer threaded surface of the sleeve to rigidly couple the collar to the sleeve. the collar also has a socket portion which cooperates with the ball portion to flexibly connect segments together to form a ball and socket-type joint. In another embodiment, the segment comprises a support member which has a threaded shaft portion and a ball surface portion. The threaded shaft portion is engageable with an inner threaded surface of a ring for rigidly coupling the support member to the ring. The ring in turn has an outer surface at one end which is threadably engageably with a hollow cylindrical sleeve. The other end of the sleeve is formed with a socket portion for engagement with a ball portion of the support member. In yet another embodiment, a secondary rod is slidably inserted in a hollow channel through the center of the segment to provide additional strength. A method for controlling a nuclear reactor utilizing the control rod assembly is also included.

Vollman, Russell E. (Solana Beach, CA)

1991-01-01

468

Tethered Rod Smectic C phase  

NSDL National Science Digital Library

Simulation Software: Glotzer Group Code Simulation Method: Brownian Dynamics A system of 800 building blocks of composition rod5b-tether6b at a concentration of 0.20, was run starting at a temperature of effecitvely infinite then instantaneously quenched to a temperature of 1.0. The system was then run for 3,000,000 time steps forming a Smetic C phase.The solve was selective for the neutral Simulation Model: United Atom Bead Spring with Lennard-Jones and FENE

Zhang, Zhenli

2005-01-31

469

Investigating Fraction Relationships with Relationship Rods  

NSDL National Science Digital Library

In this lesson plan from Illuminations, students use relationship rods to explore fraction relationships. Relationship rods range in length from one to ten centimeters, and each rod is a different color. An activity sheet with solutions, questions for students, assessment options, and suggested extension activities are included. The lesson plan is part of a five lesson plan unit, Fun with Fractions, which is cataloged separately.

Hargrove, Tracy Y.

2012-01-01

470

Impact of AD995 Alumina Rods  

Microsoft Academic Search

Gas gun experiments combined with velocity interferometric techniques have been used to determine the loading behavior of an AD995 alumina rod 19mm in diameter by 75mm and 150mm long, respectively. Graded-density materials were used to impact both bare and sleeved alumina rods, while the velocity interferometer was used to monitor the axial-velocity of the free end of the rods. Results

L. C. Chhabildas; M. D. Furnish; W. D. Reinhart; D. E. Grady

1997-01-01

471

Automatic safety rod for reactors. [LMFBR  

DOEpatents

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-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.

Germer, J.H.

1982-03-23

472

Properties of Threaded Rod Torsion Pendulums  

NASA Astrophysics Data System (ADS)

Threaded rod torsion pendulums provide an inexpensive and reasonably low-mass approach to the study of torsion pendulums in AP Physics. Characteristics such as the relationship between the torsion constant and the length and diameter of the torsion rod can be easily determined with the use of threaded rods. They can also be used for the study of damping and driven effects in torsion systems. Since the rotational inertia of a torsion pendulum is central to its behavior, the use of threaded rod systems increases the facility with which this concept can be studied.

Atalis, Alexandra; Omar, Javid

2009-04-01

473

Nuclear fuel rod end plug weld inspection  

SciTech Connect

Apparatus and method for testing TIG (tungsten inert gas) welds of end plugs on a sealed nuclear reactor fuel rod. An X-ray fluorescent spectrograph testing unit detects tungsten inclusion weld defects in the top end plug's seal weld. Separate ultrasonic weld inspection system testing units test the top end plug's seal and girth welds and test the bottom end plug's girth weld for penetration, porosity and wall thinning defects. The nuclear fuel rod is automatically moved into and out from each testing unit and is automatically transported between the testing units by rod handling devices. A controller supervises the operation of the testing units and the rod handling devices.

Parker, M. A.; Patrick, S. S.; Rice, G. F.

1985-11-19

474

Temperature actuated automatic safety rod release  

DOEpatents

A temperature-actuated apparatus is disclosed for releasably supporting a safety rod in a nuclear reactor, comprising a safety rod upper adapter having a retention means, a drive shaft which houses the upper adapter, and a bimetallic means supported within the drive shaft and having at least one ledge which engages a retention means of the safety rod upper adapter. A pre-determined increase in temperature causes the bimetallic means to deform so that the ledge disengages from the retention means, whereby the bimetallic means releases the safety rod into the core of the reactor.

Hutter, E.; Pardini, J.A.; Walker, D.E.

1984-03-13

475

Temperature actuated automatic safety rod release  

DOEpatents

A temperature-actuated apparatus is disclosed for releasably supporting a safety rod in a nuclear reactor, comprising a safety rod upper adapter having a retention means, a drive shaft which houses the upper adapter, and a bimetallic means supported within the drive shaft and having at least one ledge which engages a retention means of the safety rod upper adapter. A pre-determined increase in temperature causes the bimetallic means to deform so that the ledge disengages from the retention means, whereby the bimetallic means releases the safety rod into the core of the reactor.

Hutter, Ernest (Wilmette, IL); Pardini, John A. (Brookfield, IL); Walker, David E. (Naperville, IL)

1987-01-01

476

DSP: a protein shape string and its profile prediction server  

PubMed Central

Many studies have demonstrated that shape string is an extremely important structure representation, since it is more complete than the classical secondary structure. The shape string provides detailed information also in the regions denoted random coil. But few services are provided for systematic analysis of protein shape string. To fill this gap, we have developed an accurate shape string predictor based on two innovative technologies: a knowledge-driven sequence alignment and a sequence shape string profile method. The performance on blind test data demonstrates that the proposed method can be used for accurate prediction of protein shape string. The DSP server provides both predicted shape string and sequence shape string profile for each query sequence. Using this information, the users can compare protein structure or display protein evolution in shape string space. The DSP server is available at both http://cheminfo.tongji.edu.cn/dsp/ and its main mirror http://chemcenter.tongji.edu.cn/dsp/.

Sun, Jiangming; Tang, Shengnan; Xiong, Wenwei; Cong, Peisheng; Li, Tonghua

2012-01-01

477

DSP: a protein shape string and its profile prediction server.  

PubMed

Many studies have demonstrated that shape string is an extremely important structure representation, since it is more complete than the classical secondary structure. The shape string provides detailed information also in the regions denoted random coil. But few services are provided for systematic analysis of protein shape string. To fill this gap, we have developed an accurate shape string predictor based on two innovative technologies: a kno