Parity in knot theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manturov, Vassily O

2010-06-29

In this work we study knot theories with a parity property for crossings: every crossing is declared to be even or odd according to a certain preassigned rule. If this rule satisfies a set of simple axioms related to the Reidemeister moves, then certain simple invariants solving the minimality problem can be defined, and invariant maps on the set of knots can be constructed. The most important example of a knot theory with parity is the theory of virtual knots. Using the parity property arising from Gauss diagrams we show that even a gross simplification of the theory of virtualmore » knots, namely, the theory of free knots, admits simple and highly nontrivial invariants. This gives a solution to a problem of Turaev, who conjectured that all free knots are trivial. In this work we show that free knots are generally not invertible, and provide invariants which detect the invertibility of free knots. The passage to ordinary virtual knots allows us to strengthen known invariants (such as the Kauffman bracket) using parity considerations. We also discuss other examples of knot theories with parity. Bibliography: 27 items.« less

Statics and dynamics of DNA knotting

NASA Astrophysics Data System (ADS)

Orlandini, Enzo

2018-02-01

Knots and entanglement in polymers and biopolymers such as DNA and proteins constitute a timely topic that spans various scientific disciplines ranging from physics to chemistry, biology and mathematics. Although in the past many advancements have been made in understanding the equilibrium knotting probability and knot complexity of long polymer chains in solutions, many questions have been addressed in recent years by both experimental and theoretical means—for instance, how the knotting probability depends on the quality of the solvent, the elastic properties of the molecule and its degree of confinement. How knots form, evolve and eventually disappear in a fluctuating chain. Are the equilibrium and non-equilibrium properties of knotted molecules affected by the knot swelling/shrinking dynamics? Moreover, thanks to the great advance in nanotechnology and micromanipulation techniques, nowadays knots can be ‘manually’ tied in a single DNA molecule, followed during their motion along the chains, forced to pass through nanopores, or stretched by external forces or elongational flows. All these experimental approaches allow access to new information on the interplay of topology and polymer physics, and this has opened new perspectives in the field. Here, we provide an overview of the current knowledge of this topic, stressing the main results obtained, including the recent developments in experimental and computational approaches. Since almost all experiments on knotting involve DNA, the review will be mainly focused on the topological properties of this fascinating and biologically relevant molecule.

Changing Conceptions of Reading: Literacy Learning Instruction. Seventh Yearbook of the American Reading Forum.

ERIC Educational Resources Information Center

Lumpkin, Donavon, Ed.; And Others

Articles in this yearbook contribute to a broad perspective of changing concepts of reading, each focusing attention on an area of major factors exercising current impact on reading and on the education of reading teachers. The articles and their authors are as follows: "Learning from Text" (T. Estes); "Untying the Gordian Knot" (W. Blanton and G.…

A pseudo-haptic knot diagram interface

NASA Astrophysics Data System (ADS)

Zhang, Hui; Weng, Jianguang; Hanson, Andrew J.

2011-01-01

To make progress in understanding knot theory, we will need to interact with the projected representations of mathematical knots which are of course continuous in 3D but significantly interrupted in the projective images. One way to achieve such a goal would be to design an interactive system that allows us to sketch 2D knot diagrams by taking advantage of a collision-sensing controller and explore their underlying smooth structures through a continuous motion. Recent advances of interaction techniques have been made that allow progress to be made in this direction. Pseudo-haptics that simulates haptic effects using pure visual feedback can be used to develop such an interactive system. This paper outlines one such pseudo-haptic knot diagram interface. Our interface derives from the familiar pencil-and-paper process of drawing 2D knot diagrams and provides haptic-like sensations to facilitate the creation and exploration of knot diagrams. A centerpiece of the interaction model simulates a "physically" reactive mouse cursor, which is exploited to resolve the apparent conflict between the continuous structure of the actual smooth knot and the visual discontinuities in the knot diagram representation. Another value in exploiting pseudo-haptics is that an acceleration (or deceleration) of the mouse cursor (or surface locator) can be used to indicate the slope of the curve (or surface) of whom the projective image is being explored. By exploiting these additional visual cues, we proceed to a full-featured extension to a pseudo-haptic 4D visualization system that simulates the continuous navigation on 4D objects and allows us to sense the bumps and holes in the fourth dimension. Preliminary tests of the software show that main features of the interface overcome some expected perceptual limitations in our interaction with 2D knot diagrams of 3D knots and 3D projective images of 4D mathematical objects.

Proteins analysed as virtual knots

NASA Astrophysics Data System (ADS)

Alexander, Keith; Taylor, Alexander J.; Dennis, Mark R.

2017-02-01

Long, flexible physical filaments are naturally tangled and knotted, from macroscopic string down to long-chain molecules. The existence of knotting in a filament naturally affects its configuration and properties, and may be very stable or disappear rapidly under manipulation and interaction. Knotting has been previously identified in protein backbone chains, for which these mechanical constraints are of fundamental importance to their molecular functionality, despite their being open curves in which the knots are not mathematically well defined; knotting can only be identified by closing the termini of the chain somehow. We introduce a new method for resolving knotting in open curves using virtual knots, which are a wider class of topological objects that do not require a classical closure and so naturally capture the topological ambiguity inherent in open curves. We describe the results of analysing proteins in the Protein Data Bank by this new scheme, recovering and extending previous knotting results, and identifying topological interest in some new cases. The statistics of virtual knots in protein chains are compared with those of open random walks and Hamiltonian subchains on cubic lattices, identifying a regime of open curves in which the virtual knotting description is likely to be important.

Proteins analysed as virtual knots

PubMed Central

Alexander, Keith; Taylor, Alexander J.; Dennis, Mark R.

2017-01-01

Long, flexible physical filaments are naturally tangled and knotted, from macroscopic string down to long-chain molecules. The existence of knotting in a filament naturally affects its configuration and properties, and may be very stable or disappear rapidly under manipulation and interaction. Knotting has been previously identified in protein backbone chains, for which these mechanical constraints are of fundamental importance to their molecular functionality, despite their being open curves in which the knots are not mathematically well defined; knotting can only be identified by closing the termini of the chain somehow. We introduce a new method for resolving knotting in open curves using virtual knots, which are a wider class of topological objects that do not require a classical closure and so naturally capture the topological ambiguity inherent in open curves. We describe the results of analysing proteins in the Protein Data Bank by this new scheme, recovering and extending previous knotting results, and identifying topological interest in some new cases. The statistics of virtual knots in protein chains are compared with those of open random walks and Hamiltonian subchains on cubic lattices, identifying a regime of open curves in which the virtual knotting description is likely to be important. PMID:28205562

Optical knots and contact geometry II. From Ranada dyons to transverse and cosmetic knots

NASA Astrophysics Data System (ADS)

Kholodenko, Arkady L.

2016-08-01

Some time ago Ranada (1989) obtained new nontrivial solutions of the Maxwellian gauge fields without sources. These were reinterpreted in Kholodenko (2015) [10] (part I) as particle-like (monopoles, dyons, etc.). They were obtained by the method of Abelian reduction of the non-Abelian Yang-Mills functional. The developed method uses instanton-type calculations normally employed for the non-Abelian gauge fields. By invoking the electric-magnetic duality it then becomes possible to replace all known charges/masses by the particle-like solutions of the source-free Abelian gauge fields. To employ these results in high energy physics, it is essential to extend Ranada's results by carefully analyzing and classifying all dynamically generated knotted/linked structures in gauge fields, including those discovered by Ranada. This task is completed in this work. The study is facilitated by the recent progress made in solving the Moffatt conjecture. Its essence is stated as follows: in steady incompressible Euler-type fluids the streamlines could have knots/links of all types. By employing the correspondence between the ideal hydrodynamics and electrodynamics discussed in part I and by superimposing it with the already mentioned method of Abelian reduction, it is demonstrated that in the absence of boundaries only the iterated torus knots and links could be dynamically generated. Obtained results allow to develop further particle-knot/link correspondence studied in Kholodenko (2015) [13].

Spontaneous knotting of an agitated string.

PubMed

Raymer, Dorian M; Smith, Douglas E

2007-10-16

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

Optical knots and contact geometry II. From Ranada dyons to transverse and cosmetic knots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kholodenko, Arkady L., E-mail: string@clemson.edu

2016-08-15

Some time ago Ranada (1989) obtained new nontrivial solutions of the Maxwellian gauge fields without sources. These were reinterpreted in Kholodenko (2015) [10] (part I) as particle-like (monopoles, dyons, etc.). They were obtained by the method of Abelian reduction of the non-Abelian Yang–Mills functional. The developed method uses instanton-type calculations normally employed for the non-Abelian gauge fields. By invoking the electric–magnetic duality it then becomes possible to replace all known charges/masses by the particle-like solutions of the source-free Abelian gauge fields. To employ these results in high energy physics, it is essential to extend Ranada’s results by carefully analyzing and classifying all dynamicallymore » generated knotted/linked structures in gauge fields, including those discovered by Ranada. This task is completed in this work. The study is facilitated by the recent progress made in solving the Moffatt conjecture. Its essence is stated as follows: in steady incompressible Euler-type fluids the streamlines could have knots/links of all types. By employing the correspondence between the ideal hydrodynamics and electrodynamics discussed in part I and by superimposing it with the already mentioned method of Abelian reduction, it is demonstrated that in the absence of boundaries only the iterated torus knots and links could be dynamically generated. Obtained results allow to develop further particle-knot/link correspondence studied in Kholodenko (2015) [13].« less

Knot theory in modern chemistry.

PubMed

Horner, Kate E; Miller, Mark A; Steed, Jonathan W; Sutcliffe, Paul M

2016-11-21

Knot theory is a branch of pure mathematics, but it is increasingly being applied in a variety of sciences. Knots appear in chemistry, not only in synthetic molecular design, but also in an array of materials and media, including some not traditionally associated with knots. Mathematics and chemistry can now be used synergistically to identify, characterise and create knots, as well as to understand and predict their physical properties. This tutorial review provides a brief introduction to the mathematics of knots and related topological concepts in the context of the chemical sciences. We then survey the broad range of applications of the theory to contemporary research in the field.

Untangling the mechanics versus topology of overhand knots

NASA Astrophysics Data System (ADS)

Reis, Pedro; Jawed, Mohammad; Dieleman, Peter; Audoly, Basile

2015-03-01

We study the interplay between mechanics and topology of overhand knots in slender elastic rods. We perform precision desktop experiments of overhand knots with increasing values for the crossing number (our measure of topology) and characterize their mechanical response through tension-displacement tests. The tensile force required to tighten the knot is governed by an intricate balance between topology, bending, friction, and contact forces. Digital imaging is employed to characterize the configuration of the contact braid as a function of crossing number. A robust scaling law is found for the pulling force in terms of the geometric and topological parameters of the knot. A reduced theory is developed, which predictively rationalizes the process.

Knot probabilities in random diagrams

NASA Astrophysics Data System (ADS)

Cantarella, Jason; Chapman, Harrison; Mastin, Matt

2016-10-01

We consider a natural model of random knotting—choose a knot diagram at random from the finite set of diagrams with n crossings. We tabulate diagrams with 10 and fewer crossings and classify the diagrams by knot type, allowing us to compute exact probabilities for knots in this model. As expected, most diagrams with 10 and fewer crossings are unknots (about 78% of the roughly 1.6 billion 10 crossing diagrams). For these crossing numbers, the unknot fraction is mostly explained by the prevalence of ‘tree-like’ diagrams which are unknots for any assignment of over/under information at crossings. The data shows a roughly linear relationship between the log of knot type probability and the log of the frequency rank of the knot type, analogous to Zipf’s law for word frequency. The complete tabulation and all knot frequencies are included as supplementary data.

On universal knot polynomials

NASA Astrophysics Data System (ADS)

Mironov, A.; Mkrtchyan, R.; Morozov, A.

2016-02-01

We present a universal knot polynomials for 2- and 3-strand torus knots in adjoint representation, by universalization of appropriate Rosso-Jones formula. According to universality, these polynomials coincide with adjoined colored HOMFLY and Kauffman polynomials at SL and SO/Sp lines on Vogel's plane, respectively and give their exceptional group's counterparts on exceptional line. We demonstrate that [m,n]=[n,m] topological invariance, when applicable, take place on the entire Vogel's plane. We also suggest the universal form of invariant of figure eight knot in adjoint representation, and suggest existence of such universalization for any knot in adjoint and its descendant representations. Properties of universal polynomials and applications of these results are discussed.

BRST symmetry for a torus knot

NASA Astrophysics Data System (ADS)

Pandey, Vipul Kumar; Prasad Mandal, Bhabani

2017-08-01

We develop BRST symmetry for the first time for a particle on the surface of a torus knot by analyzing the constraints of the system. The theory contains 2nd-class constraints and has been extended by introducing the Wess-Zumino term to convert it into a theory with first-class constraints. BFV analysis of the extended theory is performed to construct BRST/anti-BRST symmetries for the particle on a torus knot. The nilpotent BRST/anti-BRST charges which generate such symmetries are constructed explicitly. The states annihilated by these nilpotent charges consist of the physical Hilbert space. We indicate how various effective theories on the surface of the torus knot are related through the generalized version of the BRST transformation with finite-field-dependent parameters.

Chance and time: Cutting the Gordian knot

NASA Astrophysics Data System (ADS)

Hagar, Amit

One of the recurrent problems in the foundations of physics is to explain why we rarely observe certain phenomena that are allowed by our theories and laws. In thermodynamics, for example, the spontaneous approach towards equilibrium is ubiquitous yet the time-reversal-invariant laws that presumably govern thermal behaviour in the microscopic level equally allow spontaneous approach away from equilibrium to occur. Why are the former processes frequently observed while the latter are almost never reported? Another example comes from quantum mechanics where the formalism, if considered complete and universally applicable, predicts the existence of macroscopic superpositions---monstrous Schrodinger cats---and these are never observed: while electrons and atoms enjoy the cloudiness of waves, macroscopic objects are always localized to definite positions. A well-known explanatory framework due to Ludwig Boltzmann traces the rarity of "abnormal" thermodynamic phenomena to the scarcity of the initial conditions that lead to it. After all, physical laws are no more than algorithms and these are expected to generate different results according to different initial conditions, hence Boltzmann's insight that violations of thermodynamic laws are possible but highly improbable. Yet Boltzmann introduces probabilities into this explanatory scheme, and since the latter is couched in terms of classical mechanics, these probabilities must be interpreted as a result of ignorance of the exact state the system is in. Quantum mechanics has taught us otherwise. Here the attempts to explain why we never observe macroscopic superpositions have led to different interpretations of the formalism and to different solutions to the quantum measurement problem. These solutions introduce additional interpretations to the meaning of probability over and above ignorance of the definite state of the physical system: quantum probabilities may result from pure chance. Notwithstanding the success of the Boltzmannian framework in explaining the thermodynamic arrow in time it leaves us with a foundational puzzle: how can ignorance play a role in scientific explanation of objective reality? In turns out that two opposing solutions to the quantum measurement problem in which probabilities arise from the stochastic character of the underlying dynamics may scratch this explanatory itch. By offering a dynamical justification to the probabilities employed in classical statistical mechanics these two interpretations complete the Boltzmannian explanatory scheme and allow us to exorcize ignorance from scientific explanations of unobserved phenomena. In this thesis I argue that the puzzle of the thermodynamic arrow in time is closely related to the problem of interpreting quantum mechanics, i.e., to the measurement problem. We may solve one by fiat and thus solve the other, but it seems unwise to try solving them independently. I substantiate this claim by presenting two possible interpretations to non-relativistic quantum mechanics. Differing as they do on the meaning of the probabilities they introduce into the otherwise deterministic dynamics, these interpretations offer alternative explanatory schemes to the standard Boltzmannian statistical mechanical explanation of thermodynamic approach to equilibrium. I then show how notwithstanding their current empirical equivalence, the two approaches diverge at the continental divide between scientific realism and anti-realism.

Weaving Knotted Vector Fields with Tunable Helicity.

PubMed

Kedia, Hridesh; Foster, David; Dennis, Mark R; Irvine, William T M

2016-12-30

We present a general construction of divergence-free knotted vector fields from complex scalar fields, whose closed field lines encode many kinds of knots and links, including torus knots, their cables, the figure-8 knot, and its generalizations. As finite-energy physical fields, they represent initial states for fields such as the magnetic field in a plasma, or the vorticity field in a fluid. We give a systematic procedure for calculating the vector potential, starting from complex scalar functions with knotted zero filaments, thus enabling an explicit computation of the helicity of these knotted fields. The construction can be used to generate isolated knotted flux tubes, filled by knots encoded in the lines of the vector field. Lastly, we give examples of manifestly knotted vector fields with vanishing helicity. Our results provide building blocks for analytical models and simulations alike.

Sedimentation of knotted polymers

NASA Astrophysics Data System (ADS)

Piili, J.; Marenduzzo, D.; Kaski, K.; Linna, R. P.

2013-01-01

We investigate the sedimentation of knotted polymers by means of stochastic rotation dynamics, a molecular dynamics algorithm that takes hydrodynamics fully into account. We show that the sedimentation coefficient s, related to the terminal velocity of the knotted polymers, increases linearly with the average crossing number nc of the corresponding ideal knot. This provides direct computational confirmation of this relation, postulated on the basis of sedimentation experiments by Rybenkov [J. Mol. Biol.10.1006/jmbi.1996.0876 267, 299 (1997)]. Such a relation was previously shown to hold with simulations for knot electrophoresis. We also show that there is an accurate linear dependence of s on the inverse of the radius of gyration Rg-1, more specifically with the inverse of the Rg component that is perpendicular to the direction along which the polymer sediments. When the polymer sediments in a slab, the walls affect the results appreciably. However, Rg-1 remains to a good precision linearly dependent on nc. Therefore, Rg-1 is a good measure of a knot's complexity.

Objective Assessment of Knot-Tying Proficiency With the Fundamentals of Arthroscopic Surgery Training Program Workstation and Knot Tester.

PubMed

Pedowitz, Robert A; Nicandri, Gregg T; Angelo, Richard L; Ryu, Richard K N; Gallagher, Anthony G

2015-10-01

To assess a new method for biomechanical assessment of arthroscopic knots and to establish proficiency benchmarks using the Fundamentals of Arthroscopic Surgery Training (FAST) Program workstation and knot tester. The first study group included 20 faculty at an Arthroscopy Association of North America resident arthroscopy course (19.9 ± 8.25 years in practice). The second group comprised 30 experienced surgeons attending an Arthroscopy Association of North America fall course (17.1 ± 19.3 years in practice). The training group included 44 postgraduate year 4 or 5 orthopaedic residents in a randomized, prospective study of proficiency-based training, with 3 subgroups: group A, standard training (n = 14); group B, workstation practice (n = 14); and group C, proficiency-based progression using the knot tester (n = 16). Each subject tied 5 arthroscopic knots backed up by 3 reversed hitches on alternating posts. Knots were tied under video control around a metal mandrel through a cannula within an opaque dome (FAST workstation). Each suture loop was stressed statically at 15 lb for 15 seconds. A calibrated sizer measured loop expansion. Knot failure was defined as 3 mm of loop expansion or greater. In the faculty group, 24% of knots "failed" under load. Performance was inconsistent: 12 faculty had all knots pass, whereas 2 had all knots fail. In the second group of practicing surgeons, 21% of the knots failed under load. Overall, 56 of 250 knots (22%) tied by experienced surgeons failed. For the postgraduate year 4 or 5 residents, the aggregate knot failure rate was 26% for the 220 knots tied. Group C residents had an 11% knot failure rate (half the overall faculty rate, P = .013). The FAST workstation and knot tester offer a simple and reproducible educational approach for enhancement of arthroscopic knot-tying skills. Our data suggest that there is significant room for improvement in the quality and consistency of these important arthroscopic skills, even for

Asymptotic laws for random knot diagrams

NASA Astrophysics Data System (ADS)

Chapman, Harrison

2017-06-01

We study random knotting by considering knot and link diagrams as decorated, (rooted) topological maps on spheres and pulling them uniformly from among sets of a given number of vertices n, as first established in recent work with Cantarella and Mastin. The knot diagram model is an exciting new model which captures both the random geometry of space curve models of knotting as well as the ease of computing invariants from diagrams. We prove that unknot diagrams are asymptotically exponentially rare, an analogue of Sumners and Whittington’s landmark result for self-avoiding polygons. Our proof uses the same key idea: we first show that knot diagrams obey a pattern theorem, which describes their fractal structure. We examine how quickly this behavior occurs in practice. As a consequence, almost all diagrams are asymmetric, simplifying sampling from this model. We conclude with experimental data on knotting in this model. This model of random knotting is similar to those studied by Diao et al, and Dunfield et al.

Knots in physics

NASA Astrophysics Data System (ADS)

Cho, Y. M.; Oh, Seung Hun; Zhang, Pengming

2018-03-01

After Dirac introduced the monopole, topological objects have played increasingly important roles in physics. In this review we discuss the role of the knot, the most sophisticated topological object in physics, and related topological objects in various areas in physics. In particular, we discuss how the knots appear in Maxwell’s theory, Skyrme theory, and multicomponent condensed matter physics.

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited

PubMed Central

Duchateau, Emmanuel; Auty, David; Mothe, Frédéric; Longuetaud, Fleur; Ung, Chhun Huor

2015-01-01

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as ‘Milton’s Law of resource availability and allocation,’ have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5,377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for ‘Milton’s Law,’ since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited.

PubMed

Duchateau, Emmanuel; Auty, David; Mothe, Frédéric; Longuetaud, Fleur; Ung, Chhun Huor; Achim, Alexis

2015-01-01

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as 'Milton's Law of resource availability and allocation,' have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5,377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for 'Milton's Law,' since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above

Knot invariants from Virasoro related representation and pretzel knots

DOE PAGES

Galakhov, D.; Melnikov, D.; Mironov, A.; ...

2015-08-06

In this study, we remind the method to calculate colored Jones polynomials for the plat representations of knot diagrams from the knowledge of modular transformation (monodromies) of Virasoro conformal blocks with insertions of degenerate fields. As an illustration we use a rich family of pretzel knots, lying on a surface of arbitrary genus g, which was recently analyzed by the evolution method. Further generalizations can be to generic Virasoro modular transformations, provided by integral kernels, which can lead to the Hikami invariants.

Vortex knots in tangled quantum eigenfunctions

PubMed Central

Taylor, Alexander J.; Dennis, Mark R.

2016-01-01

Tangles of string typically become knotted, from macroscopic twine down to long-chain macromolecules such as DNA. Here, we demonstrate that knotting also occurs in quantum wavefunctions, where the tangled filaments are vortices (nodal lines/phase singularities). The probability that a vortex loop is knotted is found to increase with its length, and a wide gamut of knots from standard tabulations occur. The results follow from computer simulations of random superpositions of degenerate eigenstates of three simple quantum systems: a cube with periodic boundaries, the isotropic three-dimensional harmonic oscillator and the 3-sphere. In the latter two cases, vortex knots occur frequently, even in random eigenfunctions at relatively low energy, and are constrained by the spatial symmetries of the modes. The results suggest that knotted vortex structures are generic in complex three-dimensional wave systems, establishing a topological commonality between wave chaos, polymers and turbulent Bose–Einstein condensates. PMID:27468801

Energy landscape of knotted protein folding

PubMed Central

Sułkowska, Joanna I.; Noel, Jeffrey K.; Onuchic, Jose N.

2012-01-01

Recent experiments have conclusively shown that proteins are able to fold from an unknotted, denatured polypeptide to the knotted, native state without the aid of chaperones. These experiments are consistent with a growing body of theoretical work showing that a funneled, minimally frustrated energy landscape is sufficient to fold small proteins with complex topologies. Here, we present a theoretical investigation of the folding of a knotted protein, 2ouf, engineered in the laboratory by a domain fusion that mimics an evolutionary pathway for knotted proteins. Unlike a previously studied knotted protein of similar length, we see reversible folding/knotting and a surprising lack of deep topological traps with a coarse-grained structure-based model. Our main interest is to investigate how evolution might further select the geometry and stiffness of the threading region of the newly fused protein. We compare the folding of the wild-type protein to several mutants. Similarly to the wild-type protein, all mutants show robust and reversible folding, and knotting coincides with the transition state ensemble. As observed experimentally, our simulations show that the knotted protein folds about ten times slower than an unknotted construct with an identical contact map. Simulated folding kinetics reflect the experimentally observed rollover in the folding limbs of chevron plots. Successful folding of the knotted protein is restricted to a narrow range of temperature as compared to the unknotted protein and fits of the kinetic folding data below folding temperature suggest slow, nondiffusive dynamics for the knotted protein. PMID:22891304

Force feedback vessel ligation simulator in knot-tying proficiency training.

PubMed

Hsu, Justin L; Korndorffer, James R; Brown, Kimberly M

2016-02-01

Tying gentle secure knots is an important skill. We have developed a force feedback simulator that measures force exerted during knot tying. This pilot study examines the benefits of this simulator in a deliberate practice curriculum. The simulator consists of silastic tubing with a force sensor. Knot quality was assessed using digital caliper measurement. Participants performed 10 vessel ligations as a pretest, then were shown force readings and tied knots until reaching proficiency targets. Average peak forces precurriculum and postcurriculum were compared using Student t test. Participants exerted significantly less force after completing the curriculum (.61 N ± .22 vs 1.42 N ± .53, P < .001), and had fewer air knots (10% vs 27%). The curriculum was completed in an average of 19.4 ± 6.27 minutes and required an average of 11.7 ± 4.03 knots to reach proficiency. This study demonstrates the feasibility of real-time feedback in learning to tie delicate knots. The curriculum can be completed in a reasonable amount of time, and may also work as a warm-up exercise before a surgical case. Copyright © 2016 Elsevier Inc. All rights reserved.

Virtual knotting in proteins and other open curves

NASA Astrophysics Data System (ADS)

Alexander, Keith; Taylor, Alexander; Dennis, Mark

Long filaments naturally knot, from string to long-chain molecules. Knotting in a filament affects its properties, and may be very stable or disappear under slight manipulation. Knotting has been identified in protein backbones for which these mechanical constraints are of fundamental importance to their function, although they are open curves in which knots are not mathematically well defined; knotting can only be identified by closing the ends of the chain. We introduce a new method for resolving knotting in open curves using virtual knots, a wider class of topological objects that do not use a classical closure, capturing the topological ambiguity of open curves. Having analysed all proteins in the Protein Data Bank by this new scheme, we recover and extend previous knotting results, and identify topological interest in some new cases. The statistics of virtual knots in proteins are compared with those of Hamiltonian subchains on cubic lattices, identifying a regime of open curves in which the virtual knotting description is likely to be important. This work was supported by the Leverhulme Trust Programme Grant ``Scientific Properties of Complex Knots'' and the EPSRC.

Torus Knots and the Topological Vertex

NASA Astrophysics Data System (ADS)

Jockers, Hans; Klemm, Albrecht; Soroush, Masoud

2014-08-01

We propose a class of toric Lagrangian A-branes on the resolved conifold that is suitable to describe torus knots on S 3. The key role is played by the transformation, which generates a general torus knot from the unknot. Applying the topological vertex to the proposed A-branes, we rederive the colored HOMFLY polynomials for torus knots, in agreement with the Rosso and Jones formula. We show that our A-model construction is mirror symmetric to the B-model analysis of Brini, Eynard and Mariño. Compared to the recent proposal by Aganagic and Vafa for knots on S 3, we demonstrate that the disk amplitude of the A-brane associated with any knot is sufficient to reconstruct the entire B-model spectral curve. Finally, the construction of toric Lagrangian A-branes is generalized to other local toric Calabi-Yau geometries, which paves the road to study knots in other three-manifolds such as lens spaces.

Knotting probability of a shaken ball-chain.

PubMed

Hickford, J; Jones, R; du Pont, S Courrech; Eggers, J

2006-11-01

We study the formation of knots on a macroscopic ball chain, which is shaken on a horizontal plate at 12 times the acceleration of gravity. We find that above a certain critical length, the knotting probability is independent of chain length, while the time to shake out a knot increases rapidly with chain length. The probability of finding a knot after a certain time is the result of the balance of these two processes. In particular, the knotting probability tends to a constant for long chains.

KymoKnot: A web server and software package to identify and locate knots in trajectories of linear or circular polymers.

PubMed

Tubiana, Luca; Polles, Guido; Orlandini, Enzo; Micheletti, Cristian

2018-06-07

The KymoKnot software package and web server identifies and locates physical knots or proper knots in a series of polymer conformations. It is mainly intended as an analysis tool for trajectories of linear or circular polymers, but it can be used on single instances too, e.g. protein structures in PDB format. A key element of the software package is the so-called minimally interfering chain closure algorithm that is used to detect physical knots in open chains and to locate the knotted region in both open and closed chains. The web server offers a user-friendly graphical interface that identifies the knot type and highlights the knotted region on each frame of the trajectory, which the user can visualize interactively from various viewpoints. The dynamical evolution of the knotted region along the chain contour is presented as a kymograph. All data can be downloaded in text format. The KymoKnot package is licensed under the BSD 3-Clause licence. The server is publicly available at http://kymoknot.sissa.it/kymoknot/interactive.php .

Optical vortex knots in tightly-focused light beams

NASA Astrophysics Data System (ADS)

Dennis, Mark; Sugic, Danica

Optical vortices, that is, zero lines of complex amplitude in a propagating light field, can be knotted or linked in a controlled way. This was demonstrated previously in experiments where a computer-controlled hologram determined the amplitude of paraxial laser light, meaning the longitudinal extent of the knot was several orders of magnitude larger than its width. We describe what happens to these optical knots when the transverse width of the beam, and hence the knot, is reduced. Outside the paraxial regime, the field's polarization becomes highly inhomogeneous, and knotted structures occur in a variety of polarization singularities. We propose experiments realising these knotted polarization structures in tightly-focused beams, which should yield optical knots of unit aspect ratio, of several optical wavelengths in size, which could be suitable for embedding knotted defect structures in liquid crystals, Bose-Einstein condensates and photopolymers. This work was supported by the Leverhulme Trust Programme Grant ''Scientific Properties of Complex Knots''.

Expression of HtKNOT1, a class I KNOX gene, overlaps cell layers and development compartments of differentiating cells in stems and flowers of Helianthus tuberosus.

PubMed

Michelotti, V; Giorgetti, L; Geri, C; Cionini, G; Pugliesi, C; Fambrini, M

2007-10-01

In plant, post-embryonic development relies on the activities of indeterminate cell populations termed meristems, spatially clustered cell lineages, wherein a subset divides indeterminately. For correct growth, the plant must maintain a constant flow of cells through the meristem, where the input of dividing pluripotent cells offsets the output of differentiating cells. KNOTTED1-like homeobox (KNOX) genes are expressed in specific patterns in the plant meristems and play important roles in maintaining meristematic cell identity. We have analyzed the expression pattern of HtKNOT1, a class I KNOX gene of Helianthus tuberosus, in stems, inflorescence meristems, floral meristems and floral organs. HtKNOT1 is expressed in cambial cells, phloem cells and xylematic parenchyma within apical stem internodes, while in basal internodes HtKNOT1 expression was restricted to the presumptive initials and recently derived phloem cells. In the reproductive phase, HtKNOT1 mRNAs were detected in both the inflorescence and floral meristems as well within lateral organ primordia (i.e. floral bracts, petals, stamens and carpels). In more differentiated flowers, the expression of HtKNOT1 was restricted to developing ovules and pollen mother cells. HtKNOT1 may play a dual role being required to maintain the meristem initials as well as initiating differentiation and/or conferring new cell identity. In particular, it is possible that HtKNOT1 cooperates at floral level with additional factors that more specifically control floral organs and pollen development in H. tuberosus.

Colored knot polynomials for arbitrary pretzel knots and links

DOE PAGES

Galakhov, D.; Melnikov, D.; Mironov, A.; ...

2015-04-01

A very simple expression is conjectured for arbitrary colored Jones and HOMFLY polynomials of a rich (g+1)-parametric family of pretzel knots and links. The answer for the Jones and HOMFLY is fully and explicitly expressed through the Racah matrix of Uq(SU N), and looks related to a modular transformation of toric conformal block. Knot polynomials are among the hottest topics in modern theory. They are supposed to summarize nicely representation theory of quantum algebras and modular properties of conformal blocks. The result reported in the present letter, provides a spectacular illustration and support to this general expectation.

Tensile strength of surgical knots in abdominal wound closure.

PubMed

Fong, Eva D M; Bartlett, Adam S R; Malak, Sharif; Anderson, Iain A

2008-03-01

Abdominal wound dehiscence is a surgical catastrophe that can be attributed to patients or technical factors. The technical properties of the monofilament sutures and knots that are commonly used in abdominal closure are poorly understood. The aim of this study was to compare the tensile strength of monofilament sutures tied with conventional knots. To do this, the knot-holding capacity of four types of knots (square, surgeons', Aberdeen and loop) were tested using three types of gauge 1 monofilament suture, namely nylon, polyglyconate and polydioxanone, using a tensiometer. We found that the knot-holding capacity of the loop knot was between twofold and threefold greater than all the other knots examined. In comparing suture types, polyglyconate had the highest knot-holding capacity for all the knots that were examined and there was no difference in the tensile strength of nylon and polyglyconate tied in a square, surgeons' or Aberdeen knot (P < 0.05). In conclusion, our findings suggest that closure of an abdominal wound would be best commenced with a loop knot, using gauge 1 polyglyconate and finished with either an Aberdeen square or surgeons' knot would be appropriate.

In Search of Functional Advantages of Knots in Proteins.

PubMed

Dabrowski-Tumanski, Pawel; Stasiak, Andrzej; Sulkowska, Joanna I

2016-01-01

We analysed the structure of deeply knotted proteins representing three unrelated families of knotted proteins. We looked at the correlation between positions of knotted cores in these proteins and such local structural characteristics as the number of intra-chain contacts, structural stability and solvent accessibility. We observed that the knotted cores and especially their borders showed strong enrichment in the number of contacts. These regions showed also increased thermal stability, whereas their solvent accessibility was decreased. Interestingly, the active sites within these knotted proteins preferentially located in the regions with increased number of contacts that also have increased thermal stability and decreased solvent accessibility. Our results suggest that knotting of polypeptide chains provides a favourable environment for the active sites observed in knotted proteins. Some knotted proteins have homologues without a knot. Interestingly, these unknotted homologues form local entanglements that retain structural characteristics of the knotted cores.

Tying Knots in DNA with Holographic Optical Tweezers

NASA Astrophysics Data System (ADS)

Miles, Mervyn; Foster, David; Seddon, Annela; Phillips, David; Carberry, David; Padgett, Miles; Dennis, Mark

It has been demonstrated that holographic optical tweezers can be used to tie a trefoil knot in double-stranded DNA. We have developed an advanced holographic optical tweezers system with several types of intuitive control interfaces. It has been used in a range of research projects including the characterization and assembly of structures. Here the process of tying increasingly complex knots with holographic tweezers will be described. The DNA is of the order of 50 μ m in length and is fluorescently labeled, in order that it can be visualized in the optical microscope of the tweezers system. With a knot was tied, the effect of increasing the persistence length of the DNA by partial methylation of the DNA molecule was investigated. Leverhulme Trust.

Characteristic length of the knotting probability revisited

NASA Astrophysics Data System (ADS)

Uehara, Erica; Deguchi, Tetsuo

2015-09-01

We present a self-avoiding polygon (SAP) model for circular DNA in which the radius of impermeable cylindrical segments corresponds to the screening length of double-stranded DNA surrounded by counter ions. For the model we evaluate the probability for a generated SAP with N segments having a given knot K through simulation. We call it the knotting probability of a knot K with N segments for the SAP model. We show that when N is large the most significant factor in the knotting probability is given by the exponentially decaying part exp(-N/NK), where the estimates of parameter NK are consistent with the same value for all the different knots we investigated. We thus call it the characteristic length of the knotting probability. We give formulae expressing the characteristic length as a function of the cylindrical radius rex, i.e. the screening length of double-stranded DNA.

Knotting probability of self-avoiding polygons under a topological constraint.

PubMed

Uehara, Erica; Deguchi, Tetsuo

2017-09-07

We define the knotting probability of a knot K by the probability for a random polygon or self-avoiding polygon (SAP) of N segments having the knot type K. We show fundamental and generic properties of the knotting probability particularly its dependence on the excluded volume. We investigate them for the SAP consisting of hard cylindrical segments of unit length and radius r ex . For various prime and composite knots, we numerically show that a compact formula describes the knotting probabilities for the cylindrical SAP as a function of segment number N and radius r ex . It connects the small-N to the large-N behavior and even to lattice knots in the case of large values of radius. As the excluded volume increases, the maximum of the knotting probability decreases for prime knots except for the trefoil knot. If it is large, the trefoil knot and its descendants are dominant among the nontrivial knots in the SAP. From the factorization property of the knotting probability, we derive a sum rule among the estimates of a fitting parameter for all prime knots, which suggests the local knot picture and the dominance of the trefoil knot in the case of large excluded volumes. Here we remark that the cylindrical SAP gives a model of circular DNA which is negatively charged and semiflexible, where radius r ex corresponds to the screening length.

Knotting probability of self-avoiding polygons under a topological constraint

NASA Astrophysics Data System (ADS)

Uehara, Erica; Deguchi, Tetsuo

2017-09-01

We define the knotting probability of a knot K by the probability for a random polygon or self-avoiding polygon (SAP) of N segments having the knot type K. We show fundamental and generic properties of the knotting probability particularly its dependence on the excluded volume. We investigate them for the SAP consisting of hard cylindrical segments of unit length and radius rex. For various prime and composite knots, we numerically show that a compact formula describes the knotting probabilities for the cylindrical SAP as a function of segment number N and radius rex. It connects the small-N to the large-N behavior and even to lattice knots in the case of large values of radius. As the excluded volume increases, the maximum of the knotting probability decreases for prime knots except for the trefoil knot. If it is large, the trefoil knot and its descendants are dominant among the nontrivial knots in the SAP. From the factorization property of the knotting probability, we derive a sum rule among the estimates of a fitting parameter for all prime knots, which suggests the local knot picture and the dominance of the trefoil knot in the case of large excluded volumes. Here we remark that the cylindrical SAP gives a model of circular DNA which is negatively charged and semiflexible, where radius rex corresponds to the screening length.

Harmonic field in knotted space

NASA Astrophysics Data System (ADS)

Duan, Xiuqing; Yao, Zhenwei

2018-04-01

Knotted fields enrich a variety of physical phenomena, ranging from fluid flows, electromagnetic fields, to textures of ordered media. Maxwell's electrostatic equations, whose vacuum solution is mathematically known as a harmonic field, provide an ideal setting to explore the role of domain topology in determining physical fields in confined space. In this work, we show the uniqueness of a harmonic field in knotted tubes, and reduce the construction of a harmonic field to a Neumann boundary value problem. By analyzing the harmonic field in typical knotted tubes, we identify the torsion driven transition from bipolar to vortex patterns. We also analogously extend our discussion to the organization of liquid crystal textures in knotted tubes. These results further our understanding about the general role of topology in shaping a physical field in confined space, and may find applications in the control of physical fields by manipulation of surface topology.

Sampling large random knots in a confined space

NASA Astrophysics Data System (ADS)

Arsuaga, J.; Blackstone, T.; Diao, Y.; Hinson, K.; Karadayi, E.; Saito, M.

2007-09-01

DNA knots formed under extreme conditions of condensation, as in bacteriophage P4, are difficult to analyze experimentally and theoretically. In this paper, we propose to use the uniform random polygon model as a supplementary method to the existing methods for generating random knots in confinement. The uniform random polygon model allows us to sample knots with large crossing numbers and also to generate large diagrammatically prime knot diagrams. We show numerically that uniform random polygons sample knots with large minimum crossing numbers and certain complicated knot invariants (as those observed experimentally). We do this in terms of the knot determinants or colorings. Our numerical results suggest that the average determinant of a uniform random polygon of n vertices grows faster than O(e^{n^2}) . We also investigate the complexity of prime knot diagrams. We show rigorously that the probability that a randomly selected 2D uniform random polygon of n vertices is almost diagrammatically prime goes to 1 as n goes to infinity. Furthermore, the average number of crossings in such a diagram is at the order of O(n2). Therefore, the two-dimensional uniform random polygons offer an effective way in sampling large (prime) knots, which can be useful in various applications.

Self-assembly of knots and links

NASA Astrophysics Data System (ADS)

Orlandini, Enzo; Polles, Guido; Marenduzzo, Davide; Micheletti, Cristian

2017-03-01

Guiding the self-assembly of identical building blocks towards complex three-dimensional structures with a set of desired properties is a major goal in material science, chemistry and physics. A particularly challenging problem, especially explored in synthetic chemistry, is that of self-assembling closed structures with a target topology starting by simple geometrical templates. Here we overview and revisit recent advancements, based on stochastic simulations, where the geometry of rigid helical templates with functionalised sticky ends has been designed for self-assembling efficiently and reproducibly into a wide range of three-dimensional closed structures. Notably, these include non trivial topologies of links and knots, including the 819 knot that we had predicted to be highly encodable and that has only recently been obtained experimentally. By appropriately tuning the parameters that define the template shape, we show that, for fixed concentration of templates, the assembly process can be directed towards the formation of specific knotted and linked structures such as the trefoils, pentafoil knots, Hopf and Solomon links. More exotic and unexpected knots and links are also found. Our results should be relevant to the design of new protocols that can both increase and broaden the population of synthetise molecular knots and catenanes.

Dramatic Growth Is Possible: Untangling Education's Gordian Knot

ERIC Educational Resources Information Center

Whittle, Chris

2006-01-01

In this article, the author discusses how, despite of the advances in today's technology, the way children are educated now is remarkably similar to how they were educated decades ago. More than any other modern-day institution, schooling is nearly impervious to change. He notes that America's "old school design" is not working with high degree of…

Haeckel or Hennig? The Gordian Knot of Characters, Development, and Procedures in Phylogeny.

ERIC Educational Resources Information Center

Dupuis, Claude

1984-01-01

Discusses the conditions for validating customary phylogenetic procedures. Concludes that the requisites of homogeneity and completeness for proved short lineages seem satisfied by the Hennigian but not the Haeckelian procedure. The epistemological antinomy of the two procedures is emphasized for the first time. (Author/RH)

Counterexamples to Moffatt's statements on vortex knots.

PubMed

Bogoyavlenskij, Oleg

2017-04-01

One of the well-known problems of hydrodynamics is studied: the problem of classification of vortex knots for ideal fluid flows. In the literature there are known Moffatt statements that all torus knots K_{m,n} for all rational numbers m/n (0knots for each one of the considered axisymmetric fluid flows. We prove that actually such a uniformity does not exist because it does not correspond to the facts. Namely, we derive a complete classification of all vortex knots realized for the fluid flows studied by Moffatt and demonstrate that the real structure of vortex knots is much more rich because the sets of mutually nonisotopic vortex knots realized for different axisymmetric fluid flows are all different. An exact formula for the limit of the hydrodynamic safety factor q_{h} at a vortex axis is derived for arbitrary axisymmetric fluid equilibria. Another exact formula is obtained for the limit of the magnetohydrodynamics safety factor q at a magnetic axis for the general axisymmetric plasma equilibria.

Explicit formulae for Chern-Simons invariants of the twist-knot orbifolds and edge polynomials of twist knots

NASA Astrophysics Data System (ADS)

Ham, J.-Y.; Lee, J.

2016-09-01

We calculate the Chern-Simons invariants of twist-knot orbifolds using the Schläfli formula for the generalized Chern-Simons function on the family of twist knot cone-manifold structures. Following the general instruction of Hilden, Lozano, and Montesinos-Amilibia, we here present concrete formulae and calculations. We use the Pythagorean Theorem, which was used by Ham, Mednykh and Petrov, to relate the complex length of the longitude and the complex distance between the two axes fixed by two generators. As an application, we calculate the Chern-Simons invariants of cyclic coverings of the hyperbolic twist-knot orbifolds. We also derive some interesting results. The explicit formulae of the A-polynomials of twist knots are obtained from the complex distance polynomials. Hence the edge polynomials corresponding to the edges of the Newton polygons of the A-polynomials of twist knots can be obtained. In particular, the number of boundary components of every incompressible surface corresponding to slope -4n+2 turns out to be 2. Bibliography: 39 titles.

Pinus pinaster Knot: A Source of Polyphenols against Plasmopara viticola.

PubMed

Gabaston, Julien; Richard, Tristan; Cluzet, Stéphanie; Palos Pinto, Antonio; Dufour, Marie-Cécile; Corio-Costet, Marie-France; Mérillon, Jean-Michel

2017-10-11

Pine knot extract from Pinus pinaster byproducts was characterized by UHPLC-DAD-MS and NMR. Fourteen polyphenols divided into four classes were identified as follows: lignans (nortrachelogenin, pinoresinol, matairesinol, isolariciresinol, secoisolariciresinol), flavonoids (pinocembrin, pinobanksin, dihydrokaempferol, taxifolin), stilbenes (pinosylvin, pinosylvin monomethyl ether, pterostilbene), and phenolic acids (caffeic acid, ferulic acid). The antifungal potential of pine knot extract, as well as the main compounds, was tested in vitro against Plasmopara viticola. The ethanolic extract showed a strong antimildew activity. In addition, pinosylvins and pinocembrin demonstrated significant inhibition of zoospore mobility and mildew development. These findings strongly suggest that pine knot is a potential biomass that could be used as a natural antifungal product.

Five Uncommon but Useful Knots.

ERIC Educational Resources Information Center

Chisnall, Rob

1997-01-01

Describes five useful, little-known knots: mooring hitch for securing a line to a stump or post; highwayman's cutaway for securing canoe lines or horses' reins; taut-line hitch or midshipman's hitch for securing tent guys; and Hedden knot and C&F belay hitch, used by rock climbers and mountaineers, which combine in a simple rescue haul system.…

On the Construction and Dynamics of Knotted Fields

NASA Astrophysics Data System (ADS)

Kedia, Hridesh

Representing a physical field in terms of its field lines has often enabled a deeper understanding of complex physical phenomena, from Faraday's law of magnetic induction, to the Helmholtz laws of vortex motion, to the free energy density of liquid crystals in terms of the distortions of the lines of the director field. At the same time, the application of ideas from topology--the study of properties that are invariant under continuous deformations--has led to robust insights into the nature of complex physical systems from defects in crystal structures, to the earth's magnetic field, to topological conservation laws. The study of knotted fields, physical fields in which the field lines encode knots, emerges naturally from the application of topological ideas to the investigation of the physical phenomena best understood in terms of the lines of a field. A knot--a closed loop tangled with itself which can not be untangled without cutting the loop--is the simplest topologically non-trivial object constructed from a line. Remarkably, knots in the vortex (magnetic field) lines of a dissipationless fluid (plasma), persist forever as they are transported by the flow, stretching and rotating as they evolve. Moreover, deeply entwined with the topology-preserving dynamics of dissipationless fluids and plasmas, is an additional conserved quantity--helicity, a measure of the average linking of the vortex (magnetic field) lines in a fluid (plasma)--which has had far-reaching consequences for fluids and plasmas. Inspired by the persistence of knots in dissipationless flows, and their far-reaching physical consequences, we seek to understand the interplay between the dynamics of a field and the topology of its field lines in a variety of systems. While it is easy to tie a knot in a shoelace, tying a knot in the the lines of a space-filling field requires contorting the lines everywhere to match the knotted region. The challenge of analytically constructing knotted field

Knots in electromagnetism

NASA Astrophysics Data System (ADS)

Arrayás, M.; Bouwmeester, D.; Trueba, J. L.

2017-01-01

Maxwell equations in vacuum allow for solutions with a non-trivial topology in the electric and magnetic field line configurations at any given moment in time. One example is a space filling congruence of electric and magnetic field lines forming circles lying on the surfaces of nested tori. In this example the electric, magnetic and Poynting vector fields are orthogonal everywhere. As time evolves the electric and magnetic fields expand and deform without changing the topology and energy, while the Poynting vector structure remains unchanged while propagating with the speed of light. The topology is characterized by the concept of helicity of the field configuration. Helicity is an important fundamental concept and for massless fields it is a conserved quantity under conformal transformations. We will review several methods by which linked and knotted electromagnetic (spin-1) fields can be derived. A first method, introduced by A. Rañada, uses the formulation of the Maxwell equations in terms of differential forms combined with the Hopf map from the three-sphere S3 to the two-sphere S2. A second method is based on spinor and twistor theory developed by R. Penrose in which elementary twistor functions correspond to the family of electromagnetic torus knots. A third method uses the Bateman construction of generating null solutions from complex Euler potentials. And a fourth method uses special conformal transformations, in particular conformal inversion, to generate new linked and knotted field configurations from existing ones. This fourth method is often accompanied by shifting singularities in the field to complex space-time points. Of course the various methods must be closely related to one another although they have been developed largely independently and they suggest different directions in which to expand the study of topologically non-trivial field configurations. It will be shown how the twistor formulation allows for a direct extension to massless

Stability of knotted vortices in wave chaos

NASA Astrophysics Data System (ADS)

Taylor, Alexander; Dennis, Mark

Large scale tangles of disordered filaments occur in many diverse physical systems, from turbulent superfluids to optical volume speckle to liquid crystal phases. They can exhibit particular large scale random statistics despite very different local physics. We have previously used the topological statistics of knotting and linking to characterise the large scale tangling, using the vortices of three-dimensional wave chaos as a universal model system whose physical lengthscales are set only by the wavelength. Unlike geometrical quantities, the statistics of knotting depend strongly on the physical system and boundary conditions. Although knotting patterns characterise different systems, the topology of vortices is highly unstable to perturbation, under which they may reconnect with one another. In systems of constructed knots, these reconnections generally rapidly destroy the knot, but for vortex tangles the topological statistics must be stable. Using large scale simulations of chaotic eigenfunctions, we numerically investigate the prevalence and impact of reconnection events, and their effect on the topology of the tangle.

The Pendulum Weaves All Knots and Links

NASA Astrophysics Data System (ADS)

Starrett, John

2003-08-01

From a topological point of view, periodic orbits of three dimensional dynamical systems are knots, that is, circles (S∧1) embedded in the three sphere (S∧3) or in R∧3. The ensemble of periodic orbits comprising the skeleton of a 3-D strange attractor form a link: a collection of (not necessarily linked) knots. Joan Birman and Robert Williams used a topological device known as the template, a branched two-manifold that results when the stable direction is collapsed out of an attractor, to analyze the knot and link types appearing in the geometric Lorenz attractor. More recently, Robert Ghrist has shown the existence of universal templates: templates that support all knot and link types. I show that the template constructed from the geometric attractor of a forced physical pendulum contains a universal template as a subtemplate, and therefore the orbit set of the pendulum contains every knot and link type.

Motion of Knots in DNA Stretched by Elongational Fields

NASA Astrophysics Data System (ADS)

Klotz, Alexander R.; Soh, Beatrice W.; Doyle, Patrick S.

2018-05-01

Knots in DNA occur in biological systems, serve as a model system for polymer entanglement, and affect the efficacy of modern genomics technologies. We study the motion of complex knots in DNA by stretching molecules with a divergent electric field that provides an elongational force. We demonstrate that the motion of knots is nonisotropic and driven towards the closest end of the molecule. We show for the first time experimentally that knots can go from a mobile to a jammed state by varying an applied strain rate, and that this jamming is reversible. We measure the mobility of knots as a function of strain rate, demonstrating the conditions under which knots can be driven towards the ends of the molecule and untied.

Properties of knotted ring polymers. I. Equilibrium dimensions.

PubMed

Mansfield, Marc L; Douglas, Jack F

2010-07-28

We report calculations on three classes of knotted ring polymers: (1) simple-cubic lattice self-avoiding rings (SARs), (2) "true" theta-state rings, i.e., SARs generated on the simple-cubic lattice with an attractive nearest-neighbor contact potential (theta-SARs), and (3) ideal, Gaussian rings. Extrapolations to large polymerization index N imply knot localization in all three classes of chains. Extrapolations of our data are also consistent with conjectures found in the literature which state that (1) R(g)-->AN(nu) asymptotically for ensembles of random knots restricted to any particular knot state, including the unknot; (2) A is universal across knot types for any given class of flexible chains; and (3) nu is equal to the standard self-avoiding walk (SAW) exponent (congruent with 0.588) for all three classes of chains (SARs, theta-SARs, and ideal rings). However, current computer technology is inadequate to directly sample the asymptotic domain, so that we remain in a crossover scaling regime for all accessible values of N. We also observe that R(g) approximately p(-0.27), where p is the "rope length" of the maximally inflated knot. This scaling relation holds in the crossover regime, but we argue that it is unlikely to extend into the asymptotic scaling regime where knots become localized.

On the universality of knot probability ratios

NASA Astrophysics Data System (ADS)

Janse van Rensburg, E. J.; Rechnitzer, A.

2011-04-01

Let pn denote the number of self-avoiding polygons of length n on a regular three-dimensional lattice, and let pn(K) be the number which have knot type K. The probability that a random polygon of length n has knot type K is pn(K)/pn and is known to decay exponentially with length (Sumners and Whittington 1988 J. Phys. A: Math. Gen. 21 1689-94, Pippenger 1989 Discrete Appl. Math. 25 273-8). Little is known rigorously about the asymptotics of pn(K), but there is substantial numerical evidence (Orlandini et al 1988 J. Phys. A: Math. Gen. 31 5953-67, Marcone et al 2007 Phys. Rev. E 75 41105, Rawdon et al 2008 Macromolecules 41 4444-51, Janse van Rensburg and Rechnitzer 2008 J. Phys. A: Math. Theor. 41 105002) that pn(K) grows as p_n(K) \\simeq C_K \\mu _\\emptyset ^n n^{\\alpha -3+N_K}, \\qquad as\\quad n \\rightarrow \\infty, where NK is the number of prime components of the knot type K. It is believed that the entropic exponent, α, is universal, while the exponential growth rate, μ∅, is independent of the knot type but varies with the lattice. The amplitude, CK, depends on both the lattice and the knot type. The above asymptotic form implies that the relative probability of a random polygon of length n having prime knot type K over prime knot type L is \\frac{p_n(K)/p_n}{p_n(L)/p_n} = \\frac{p_n(K)}{p_n(L)} \\simeq \\left[ \\frac{C_K}{C_L} \\right].\\\\[-8pt] In the thermodynamic limit this probability ratio becomes an amplitude ratio; it should be universal and depend only on the knot types K and L. In this communication we examine the universality of these probability ratios for polygons in the simple cubic, face-centred cubic and body-centred cubic lattices. Our results support the hypothesis that these are universal quantities. For example, we estimate that a long random polygon is approximately 28 times more likely to be a trefoil than be a figure-eight, independent of the underlying lattice, giving an estimate of the intrinsic entropy associated with knot

Evolution method and ``differential hierarchy'' of colored knot polynomials

NASA Astrophysics Data System (ADS)

Mironov, A.; Morozov, A.; Morozov, And.

2013-10-01

We consider braids with repeating patterns inside arbitrary knots which provides a multi-parametric family of knots, depending on the "evolution" parameter, which controls the number of repetitions. The dependence of knot (super)polynomials on such evolution parameters is very easy to find. We apply this evolution method to study of the families of knots and links which include the cases with just two parallel and anti-parallel strands in the braid, like the ordinary twist and 2-strand torus knots/links and counter-oriented 2-strand links. When the answers were available before, they are immediately reproduced, and an essentially new example is added of the "double braid", which is a combination of parallel and anti-parallel 2-strand braids. This study helps us to reveal with the full clarity and partly investigate a mysterious hierarchical structure of the colored HOMFLY polynomials, at least, in (anti)symmetric representations, which extends the original observation for the figure-eight knot to many (presumably all) knots. We demonstrate that this structure is typically respected by the t-deformation to the superpolynomials.

In vitro evaluation of square and surgeon's knots in large gauge suture.

PubMed

Gillen, Alex M; Munsterman, Amelia S; Farag, Ramsis; Coleridge, Matthew O D; Hanson, R Reid

2017-02-01

To investigate the strength and size of surgeon's and square knots for starting and ending continuous suture lines using large gauge suture. In vitro mechanical study. Knotted suture. Surgeon's and square knots were tested using 2 and 3 USP polyglactin 910 and 2 USP polydioxanone under linear tension on a universal testing machine. Failure mode and knot holding capacity (KHC) were recorded, and relative knot security (RKS) was calculated as a percentage of KHC. Comparisons were made between number of throws, suture size, suture type, and knot types. Knot volume and weight were assessed by a digital micrometer and balance, respectively. There were no significant differences in KHC (P = .295), RKS (P = .307), volume (P = .128), or weight (P = .310) between square and surgeon's knots at the start or end of suture lines with the same number of throws and suture type. A minimum of 6 throws were required for start knots and 7 throws at end knots to prevent unraveling. Knots tied with 3 polyglactin 910 were strongest (P < .001) and 2 polyglactin 910 produced knots with higher KHC and RKS than 2 polydioxanone (P < .001). No consistent differences were detected between knots types tied with the same suture material; however, number of throws affected KHC and RKS up to 6 throws in start or 7 throws in end knots. The configuration of square and surgeon's knots performed at the end of a continuous line alters their KHC, supporting the use of additional throws for knot security. © 2017 The American College of Veterinary Surgeons.

Influence of emergency physician's tying technique on knot security.

PubMed

Batra, E K; Franz, D A; Towler, M A; Rodeheaver, G T; Thacker, J G; Zimmer, C A; Edlich, R F

1992-01-01

The purpose of this study was to determine the influence of emergency physician's tying technique on knot security using 2-0 and 4-0 monofilament and multifilament nylon sutures. Using an Instron Tensile Tester and a portable tensiometer, knot security was achieved with these sutures using four-throw square knots (1 = 1 = 1 = 1). After didactic and psychomotor skill training, medical students were taught to construct the four-throw square knot using either a two-hand tie or an instrument tie. Using the portable tensiometer, their knot tying techniques were judged to be superior to those used by emergency physicians. The emergency physician's faulty technique can easily be corrected by didactic information and psychomotor skill training.

Escape of a knot from a DNA molecule in flow

NASA Astrophysics Data System (ADS)

Renner, Benjamin; Doyle, Patrick

2014-03-01

Macroscale knots are an everyday occurrence when trying to unravel an unorganized flexible string (e.g. an iPhone cord taken out of your pocket). In nature, knots are found in proteins and viral capsid DNA, and the properties imbued by their topologies are thought to have biological significance. Unlike their macroscale counterparts, thermal fluctuations greatly influence the dynamics of polymer knots. Here, we use Brownian Dynamics simulations to study knot diffusion along a linear polymer chain. The model is parameterized to dsDNA, a model polymer used in previous simulation and experimental studies of knot dynamics. We have used this model to study the process of knot escape and transport along a dsDNA strand extended by an elongational flow. For a range of knot topologies and flow strengths, we show scalings that result in collapse of the data onto a master curve. We show a topologically mediated mode of transport coincides with observed differences in rates of knot transport, and we provide a simple mechanistic explanation for its effect. We anticipate these results will build on the growing body of fundamental studies of knotted polymers and inform future experimental study. This work is supported by the Singapore-MIT Alliance for Research and Technology (SMART) and National Science Foundation (NSF) grant CBET-0852235.

Comparing models of Red Knot population dynamics

USGS Publications Warehouse

McGowan, Conor P.

2015-01-01

Predictive population modeling contributes to our basic scientific understanding of population dynamics, but can also inform management decisions by evaluating alternative actions in virtual environments. Quantitative models mathematically reflect scientific hypotheses about how a system functions. In Delaware Bay, mid-Atlantic Coast, USA, to more effectively manage horseshoe crab (Limulus polyphemus) harvests and protect Red Knot (Calidris canutus rufa) populations, models are used to compare harvest actions and predict the impacts on crab and knot populations. Management has been chiefly driven by the core hypothesis that horseshoe crab egg abundance governs the survival and reproduction of migrating Red Knots that stopover in the Bay during spring migration. However, recently, hypotheses proposing that knot dynamics are governed by cyclical lemming dynamics garnered some support in data analyses. In this paper, I present alternative models of Red Knot population dynamics to reflect alternative hypotheses. Using 2 models with different lemming population cycle lengths and 2 models with different horseshoe crab effects, I project the knot population into the future under environmental stochasticity and parametric uncertainty with each model. I then compare each model's predictions to 10 yr of population monitoring from Delaware Bay. Using Bayes' theorem and model weight updating, models can accrue weight or support for one or another hypothesis of population dynamics. With 4 models of Red Knot population dynamics and only 10 yr of data, no hypothesis clearly predicted population count data better than another. The collapsed lemming cycle model performed best, accruing ~35% of the model weight, followed closely by the horseshoe crab egg abundance model, which accrued ~30% of the weight. The models that predicted no decline or stable populations (i.e. the 4-yr lemming cycle model and the weak horseshoe crab effect model) were the most weakly supported.

Biomarkers of head and neck cancer, tools or a gordian knot?

PubMed Central

Lampri, Evangeli S; Chondrogiannis, Georgios; Ioachim, Elli; Varouktsi, Anna; Mitselou, Antigoni; Galani, Aggeliki; Briassoulis, Evangelos; Kanavaros, Panagiotis; Galani, Vasiliki

2015-01-01

Head and neck tumors comprise a wide spectrum of heterogeneous neoplasms for which biomarkers are needed to aid in earlier diagnosis, risk assessment and therapy response. Personalized medicine based on predictive markers linked to drug response, it is hoped, will lead to improvements in outcomes and avoidance of unnecessary treatment in carcinoma of the head and neck. Because of the heterogeneity of head and neck tumors, the integration of multiple selected markers in association with the histopathologic features is advocated for risk assessment. Validation of each biomarker in the context of clinical trials will be required before a specific marker can be incorporated into daily practice. Furthermore, we will give evidence that some proteins implicated in cell-cell interaction, such as CD44 may be involved in the multiple mechanism of the development and progression of laryngeal lesions and may help to predict the risk of transformation of the benign or precancerous lesions to cancer. PMID:26379825

Biomarkers of head and neck cancer, tools or a gordian knot?

PubMed

Lampri, Evangeli S; Chondrogiannis, Georgios; Ioachim, Elli; Varouktsi, Anna; Mitselou, Antigoni; Galani, Aggeliki; Briassoulis, Evangelos; Kanavaros, Panagiotis; Galani, Vasiliki

2015-01-01

Head and neck tumors comprise a wide spectrum of heterogeneous neoplasms for which biomarkers are needed to aid in earlier diagnosis, risk assessment and therapy response. Personalized medicine based on predictive markers linked to drug response, it is hoped, will lead to improvements in outcomes and avoidance of unnecessary treatment in carcinoma of the head and neck. Because of the heterogeneity of head and neck tumors, the integration of multiple selected markers in association with the histopathologic features is advocated for risk assessment. Validation of each biomarker in the context of clinical trials will be required before a specific marker can be incorporated into daily practice. Furthermore, we will give evidence that some proteins implicated in cell-cell interaction, such as CD44 may be involved in the multiple mechanism of the development and progression of laryngeal lesions and may help to predict the risk of transformation of the benign or precancerous lesions to cancer.

Universal properties of knotted polymer rings.

PubMed

Baiesi, M; Orlandini, E

2012-09-01

By performing Monte Carlo sampling of N-steps self-avoiding polygons embedded on different Bravais lattices we explore the robustness of universality in the entropic, metric, and geometrical properties of knotted polymer rings. In particular, by simulating polygons with N up to 10(5) we furnish a sharp estimate of the asymptotic values of the knot probability ratios and show their independence on the lattice type. This universal feature was previously suggested, although with different estimates of the asymptotic values. In addition, we show that the scaling behavior of the mean-squared radius of gyration of polygons depends on their knot type only through its correction to scaling. Finally, as a measure of the geometrical self-entanglement of the self-avoiding polygons we consider the standard deviation of the writhe distribution and estimate its power-law behavior in the large N limit. The estimates of the power exponent do depend neither on the lattice nor on the knot type, strongly supporting an extension of the universality property to some features of the geometrical entanglement.

The Effect on Performance Time and Quality of the Knots after Mono or Bimanual Training of Laparoscopic Intracorporeal Knot Tying according to the Gladiator Rule Technique.

PubMed

Asencio, Fernanda de Almeida; Ribeiro, Helizabet Abdala Salomão Ayroza; Romeo, Armando; Wattiez, Arnauld; Ribeiro, Paulo Augusto Galvão Ayroza

2018-05-18

 To assess whether the monomanual or bimanual training of laparoscopic suture following the same technique may interfere with the knots' performance time and/or quality.  A prospective observational study involving 41 resident students of gynecology/obstetrics and general surgery who attended a laparoscopic suture training for 2 days. The participants were divided into two groups. Group A performed the training using exclusively their dominant hand, and group B performed the training using both hands to tie the intracorporeal knot. All participants followed the same technique, called Romeo Gladiator Rule. At the end of the course, the participants were asked to perform three exercises to assess the time it took them to tie the knots, as well as the quality of the knots.  A comparative analysis of the groups showed that there was no statistically significant difference ( p  = 0.334) between them regarding the length of time to tie one knot. However, when the time to tie 10 consecutive knots was compared, group A was faster than group B ( p  = 0.020). A comparison of the knot loosening average, in millimeters, revealed that the knots made by group B loosened less than those made by group A, but there was no statistically significant difference regarding the number of knots that became untied.  This study demonstrated that the knots from group B showed better quality than those from group A, with lower loosening measures and more strength necessary to untie the knots. The study also demonstrated that group A was faster than B when the time to tie ten consecutive knots was compared. Thieme Revinter Publicações Ltda Rio de Janeiro, Brazil.

Effect of knots on stress waves in lumber

Treesearch

C.C. Gerhards

1982-01-01

An impact stress wave was induced in the end of 2 by 6 lumber containing knots. Rather than a normal, perpendicular-to-the-axis profile in transiting by a knot, the stress wave tended to Iead in zones of clear wood in the direction of the slope of grain or slope of the annual rings and to lag behind the knot. Of three methods evaluated to time the stress wave, the...

Lattice stick number of knots

NASA Astrophysics Data System (ADS)

Huang, Yuanfei; Yang, Weiling

2017-12-01

The minimal number of straight line segments required to construct a polygonal presentation of the knot K in the cubic lattice is called the lattice stick number of the knot K, denoted by S_L(K) . It is known that S_L(K)≥slant15 if the crossing number of K, C_r(K) , satisfies C_r(K)≥slant5 , and the main result of this paper is to improve this to S_L(K)≥slant16 if C_r(K)≥slant5 . Furthermore, we will show that S_L(K)=16 for K=51 and K=52 which implies that this lower bound cannot be improved except for knots with higher crossing numbers. Project supported by the NSFC grants 11531006, 11371367 and 11271290, and the Fundamental Research Funds for the Central Universities 20720160038 and Fujian Province young and middle-aged teacher education research project JA15016.

Asymptotics of knotted lattice polygons

NASA Astrophysics Data System (ADS)

Orlandini, E.; Tesi, M. C.; Janse van Rensburg, E. J.; Whittington, S. G.

1998-07-01

We use Monte Carlo methods to investigate the asymptotic behaviour of the number and mean-square radius of gyration of polygons in the simple cubic lattice with fixed knot type. Let 0305-4470/31/28/010/img7 be the number of n-edge polygons of a fixed knot type 0305-4470/31/28/010/img8 in the cubic lattice, and let 0305-4470/31/28/010/img9 be the mean square radius of gyration of all the polygons counted by 0305-4470/31/28/010/img7. If we assume that 0305-4470/31/28/010/img11, where 0305-4470/31/28/010/img12 is the growth constant of polygons of knot type 0305-4470/31/28/010/img8, and 0305-4470/31/28/010/img14 is the entropic exponent of polygons of knot type 0305-4470/31/28/010/img8, then our numerical data are consistent with the relation 0305-4470/31/28/010/img16, where 0305-4470/31/28/010/img17 is the unknot and 0305-4470/31/28/010/img18 is the number of prime factors of the knot 0305-4470/31/28/010/img8. If we assume that 0305-4470/31/28/010/img20, then our data are consistent with both 0305-4470/31/28/010/img21 and 0305-4470/31/28/010/img22 being independent of 0305-4470/31/28/010/img8. These results support the claims made in Janse van Rensburg and Whittington (1991a 24 3935) and Orlandini et al (1996 29 L299, 1998 Topology and Geometry in Polymer Science (IMA Volumes in Mathematics and its Applications) (Berlin: Springer)).

Accomplishments of a 10-year initiative to develop host plant resistance to root-knot and reniform nematodes in cotton

USDA-ARS?s Scientific Manuscript database

In 2003 Cotton Incorporated initiated a Beltwide research program to develop host plant resistance against root-knot (Meloidogyne incognita) and reniform (Rotylenchulus reniformis) nematodes. Objectives formulated at a coordinating meeting in 2003 that included participants from public institutions...

Determination of the intersegmental plane using the slip-knot method

PubMed Central

Endoh, Makoto; Kato, Hirohisa; Suzuki, Jun; Watarai, Hikaru; Hamada, Akira; Suzuki, Katsuyuki; Nakahashi, Kenta; Sadahiro, Mitsuaki

2018-01-01

Background Visualization of intersegmental planes in the lung is desirable for precise anatomical lung segmentectomy. We developed the slip-knot method for creating inflation-deflation lines. This study aimed to assess relevant data for thoracoscopic segmentectomy performed using this method. Methods In the slip-knot method, the objective segmental bronchus is looped with a monofilament thread. One end of the thread is then pulled during temporary bilateral ventilation, causing the knot to slip toward the bronchus. Thereafter, bronchial ligation is tightened to block the outflow of segmental air, ensuring that the segment remains expanded while the other reserved segments collapse on resumption of unilateral ventilation. Data from 221 patients who underwent thoracoscopic pulmonary segmentectomy between 2010 and 2016 were analyzed. Results A total of 147 patients (67%) were indicated for the slip-knot method, and 74 cases (33%) were non-adaptive cases. Ninety six percent of 147 cases were well adapted to the slip-knot method, which allowed us to obtain good inflation-deflation line images to determine the intersegmental plane. The mean operative time was 171±51 min (range, 71–367 min). The mean duration of chest tube insertion was 1.5±1.2 days (range, 1–7 days). Three cases (2.0%) had prolonged air-leakage and one (0.7%) case had readmission for late air-leakage. Conclusions Our method enables determination of anatomical intersegmental planes using only one monofilament thread, thus facilitating thoracoscopic pulmonary anatomical segmentectomy. PMID:29785297

Stable elastic knots with no self-contact

NASA Astrophysics Data System (ADS)

Moulton, Derek E.; Grandgeorge, Paul; Neukirch, Sébastien

2018-07-01

We study an elastic rod bent into an open trefoil knot and clamped at both ends. The question we consider is whether there are stable configurations for which there are no points of self-contact. This idea can be fairly easily replicated with a thin strip of paper, but is more difficult or even impossible with a flexible wire. We search for such configurations within the space of three tuning parameters related to the degrees of freedom in a simple experiment. Mathematically, we show, both within standard Kirchhoff theory as well within an elastic strip theory, that stable and contact-free knotted configurations can be found, and we classify the corresponding parametric regions. Numerical results are complemented with an asymptotic analysis that demonstrates the presence of knots near the doubly-covered ring. In the case of the strip model, quantitative experiments of the region of good knots are also provided to validate the theory.

Probe Knots and Hopf Insulators with Ultracold Atoms

NASA Astrophysics Data System (ADS)

Deng, Dong-Ling; Wang, Sheng-Tao; Sun, Kai; Duan, L.-M.

2018-01-01

Knots and links are fascinating and intricate topological objects. Their influence spans from DNA and molecular chemistry to vortices in superfluid helium, defects in liquid crystals and cosmic strings in the early universe. Here we find that knotted structures also exist in a peculiar class of three-dimensional topological insulators—the Hopf insulators. In particular, we demonstrate that the momentum-space spin textures of Hopf insulators are twisted in a nontrivial way, which implies the presence of various knot and link structures. We further illustrate that the knots and nontrivial spin textures can be probed via standard time-of-flight images in cold atoms as preimage contours of spin orientations in stereographic coordinates. The extracted Hopf invariants, knots, and links are validated to be robust to typical experimental imperfections. Our work establishes the existence of knotted structures in Hopf insulators, which may have potential applications in spintronics and quantum information processing. D.L.D., S.T.W. and L.M.D. are supported by the ARL, the IARPA LogiQ program, and the AFOSR MURI program, and supported by Tsinghua University for their visits. K.S. acknowledges the support from NSF under Grant No. PHY1402971. D.L.D. is also supported by JQI-NSF-PFC and LPS-MPO-CMTC at the final stage of this paper.

Developing an Objective Structured Assessment of Technical Skills for Laparoscopic Suturing and Intracorporeal Knot Tying.

PubMed

Chang, Olivia H; King, Louise P; Modest, Anna M; Hur, Hye-Chun

2016-01-01

To develop a teaching and assessment tool for laparoscopic suturing and intracorporeal knot tying. We designed an Objective Structured Assessment of Technical Skills (OSATS) tool that includes a procedure-specific checklist (PSC) and global rating scale (GRS) to assess laparoscopic suturing and intracorporeal knot-tying performance. Obstetrics and Gynecology residents at our institution were videotaped while performing a laparoscopic suturing and intracorporeal knot-tying task at a surgical simulation workshop. A total of 2 expert reviewers assessed resident performance using the OSATS tool during live performance and 1 month later using the videotaped recordings. OSATS scores were analyzed using the Wilcoxon rank-sum test. Data are presented as median scores (interquartile range [IQR]). Intrarater and interrater reliabilities were assessed using a Spearman correlation and are presented as an r correlation coefficient and p value. An r ≥ 0.8 was considered as a high correlation. After testing, we received feedback from residents and faculty to improve the OSATS tool as part of an iterative design process. In all, 14 of 21 residents (66.7%) completed the study, with 9 junior residents and 5 senior residents. Junior residents had a lower score on the PSC than senior residents did; however, this was not statistically significant (median = 6.0 [IQR: 4.0-10.0] and median = 13.0 [IQR: 10.0-13.0]; p = 0.09). There was excellent intrarater reliability with our OSATS tool (for PSC component, r = 0.88 for Rater 1 and 0.93 for Rater 2, both p < 0.0001; for GRS component, r = 0.85 for Rater 1 and 0.88 for Rater 2, both p ≤ 0.0002). The PSC also has high interrater reliability during live evaluation (r = 0.92; p < 0.0001), and during the videotape scoring with r = 0.77 (p = 0.001). Our OSATS tool may be a useful assessment and teaching tool for laparoscopic suturing and intracorporeal knot-tying skills. Overall, good intrarater reliability was demonstrated, suggesting that

Interplay between writhe and knotting for swollen and compact polymers.

PubMed

Baiesi, Marco; Orlandini, Enzo; Whittington, Stuart G

2009-10-21

The role of the topology and its relation with the geometry of biopolymers under different physical conditions is a nontrivial and interesting problem. Aiming at understanding this issue for a related simpler system, we use Monte Carlo methods to investigate the interplay between writhe and knotting of ring polymers in good and poor solvents. The model that we consider is interacting self-avoiding polygons on the simple cubic lattice. For polygons with fixed knot type, we find a writhe distribution whose average depends on the knot type but is insensitive to the length N of the polygon and to solvent conditions. This "topological contribution" to the writhe distribution has a value that is consistent with that of ideal knots. The standard deviation of the writhe increases approximately as square root(N) in both regimes, and this constitutes a geometrical contribution to the writhe. If the sum over all knot types is considered, the scaling of the standard deviation changes, for compact polygons, to approximately N(0.6). We argue that this difference between the two regimes can be ascribed to the topological contribution to the writhe that, for compact chains, overwhelms the geometrical one, thanks to the presence of a large population of complex knots at relatively small values of N. For polygons with fixed writhe, we find that the knot distribution depends on the chosen writhe, with the occurrence of achiral knots being considerably suppressed for large writhe. In general, the occurrence of a given knot thus depends on a nontrivial interplay between writhe, chain length, and solvent conditions.

Tying a molecular knot with optical tweezers

NASA Astrophysics Data System (ADS)

Arai, Yasuharu; Yasuda, Ryohei; Akashi, Ken-Ichirou; Harada, Yoshie; Miyata, Hidetake; Kinosita, Kazuhiko; Itoh, Hiroyasu

1999-06-01

Filamentous structures are abundant in cells. Relatively rigid filaments, such as microtubules and actin, serve as intracellular scaffolds that support movement and force, and their mechanical properties are crucial to their function in the cell. Some aspects of the behaviour of DNA, meanwhile, depend critically on its flexibility-for example, DNA-binding proteins can induce sharp bends in the helix. The mechanical characterization of such filaments has generally been conducted without controlling the filament shape, by the observation of thermal motions or of the response to external forces or flows. Controlled buckling of a microtubule has been reported, but the analysis of the buckled shape was complicated. Here we report the continuous control of the radius of curvature of a molecular strand by tying a knot in it, using optical tweezers to manipulate the strand's ends. We find that actin filaments break at the knot when the knot diameter falls below 0.4µm. The pulling force at breakage is around 1pN, two orders of magnitude smaller than the tensile stress of a straight filament. The flexural rigidity of the filament remained unchanged down to this diameter. We have also knotted a single DNA molecule, opening up the possibility of studying curvature-dependent interactions with associated proteins. We find that the knotted DNA is stronger than actin.

Topological effects on the mechanical properties of polymer knots

NASA Astrophysics Data System (ADS)

Zhao, Yani; Ferrari, Franco

2017-11-01

The mechanical properties of knotted polymer rings under stretching in a bad or good solvent are investigated by applying a force F to a point of the knot while keeping another point fixed. The Monte Carlo sampling of the polymer conformations is performed on a simple cubic lattice using the Wang-Landau algorithm. The specific energy, specific heat capacity, gyration radius and the force-elongation curves are computed for several knot topologies with lengths up to 120 lattice units. The common features of the mechanical and thermal behavior of stretched short polymer rings forming knots of a given topological type are analyzed as well as the differences arising due to topology and size effects. It is found that these systems admit three different phases depending on the values of the tensile force F and the temperature T. The transitions from one phase to the other are well characterized by the peaks of the specific heat capacity and by the data of the gyration radius and specific energy. At very low temperatures the force-elongation curves show that the stretching of a knot is a stepwise process, which becomes smooth at higher temperatures. Criteria for distinguishing topological and size effects are provided. It turns out from our study that the behavior of short polymer rings is strongly influenced by topological effects. In particular, the swelling and the swelling rate of knots are severely limited by the topological constraints. Several other properties that are affected by topology, like the decay of the specific energy at high tensile forces, are discussed. The fading out of the influences of topological origin with increasing knot lengths has been verified. Some anomalies detected in the plots of the specific heat capacity of very short and complex knots have been explained by the limitations in the number of accessible energy states due to the topological constraints.

Comparing the tensile strength of square and reversing half-hitch alternating post knots

PubMed Central

Wu, Vincent; Sykes, Edward A.; Mercer, Dale; Hopman, Wilma M.; Tang, Ephraim

2017-01-01

Background Square knots are the gold standard in hand-tie wound closure, but are difficult to reproduce in deep cavities, inadvertently resulting in slipknots. The reversing half-hitch alternating post (RHAP) knot has been suggested as an alternative owing to its nonslip nature and reproducibility in limited spaces. We explored whether the RHAP knot is noninferior to the square knot by assessing tensile strength. Methods We conducted 10 trials for each baseline and knot configuration, using 3–0 silk and 3–0 polyglactin 910 sutures. We compared tensile strength between knot configurations at the point of knot failure between slippage and breakage. Results Maximal failure strength (mean ± SD) in square knots was reached with 4-throw in both silk (30 ± 1.5 N) and polyglactin 910 (39 ± 12 N). For RHAP knots, maximal failure strength was reached at 5-throw for both silk (31 ± 1.5 N) and polyglactin 910 (41 ± 13 N). In both sutures, there were no strength differences between 3-throw square and 4-throw RHAP, between 4-throw square and 5-throw RHAP, or between 5-throw square and 6-throw RHAP knots. Polyglactin 910 sutures, in all knot configurations, were more prone to slippage than silk sutures (p < 0.001). Conclusion The difference in mean tensile strength could be attributed to the proportion of knot slippage versus breakage, which is material-dependent. Future studies can re-evaluate findings in monofilament sutures and objectively assess the reproducibility of square and RHAP knots in deep cavities. Our results indicate that RHAP knots composed of 1 extra throw provide equivalent strength to square knots and may be an alternative when performing hand-ties in limited cavities with either silk or polyglactin 910 sutures. PMID:28327276

Comparing the tensile strength of square and reversing half-hitch alternating post knots.

PubMed

Wu, Vincent; Sykes, Edward A; Mercer, Dale; Hopman, Wilma M; Tang, Ephraim

2017-06-01

Square knots are the gold standard in hand-tie wound closure, but are difficult to reproduce in deep cavities, inadvertently resulting in slipknots. The reversing half-hitch alternating post (RHAP) knot has been suggested as an alternative owing to its nonslip nature and reproducibility in limited spaces. We explored whether the RHAP knot is noninferior to the square knot by assessing tensile strength. We conducted 10 trials for each baseline and knot configuration, using 3-0 silk and 3-0 polyglactin 910 sutures. We compared tensile strength between knot configurations at the point of knot failure between slippage and breakage. Maximal failure strength (mean ± SD) in square knots was reached with 4-throw in both silk (30 ± 1.5 N) and polyglactin 910 (39 ± 12 N). For RHAP knots, maximal failure strength was reached at 5-throw for both silk (31 ± 1.5 N) and polyglactin 910 (41 ± 13 N). In both sutures, there were no strength differences between 3-throw square and 4-throw RHAP, between 4-throw square and 5-throw RHAP, or between 5-throw square and 6-throw RHAP knots. Polyglactin 910 sutures, in all knot configurations, were more prone to slippage than silk sutures ( p < 0.001). The difference in mean tensile strength could be attributed to the proportion of knot slippage versus breakage, which is material-dependent. Future studies can re-evaluate findings in monofilament sutures and objectively assess the reproducibility of square and RHAP knots in deep cavities. Our results indicate that RHAP knots composed of 1 extra throw provide equivalent strength to square knots and may be an alternative when performing hand-ties in limited cavities with either silk or polyglactin 910 sutures.

Axial-spin technique of endoscopic intracorporeal knot tying: comparison with the conventional technique and objective assessment of knot security, learning curves, and performance efficiency across training levels.

PubMed

Gopaldas, Raja R; Rohatgi, Chand

2009-04-01

A major limitation of conventional laparoscopic surgery is the placement of an intracorporeal (IC) knot, which requires a significant amount of training and practice. An easier technique of IC knot tying using 90-degree grasper is compared with the conventional technique (CLT). The new axial-spin technique (AST) uses the spin of the instrument shaft to tie IC knots. Fourteen participants stratified into 3 training levels were instructed to tie 50 reef IC knots using each technique on trainers in 3 sessions. The final 5 knots tied using each technique were deemed to be representative of maximal performance efficiency (PE) and randomly subject to tensile strength measurements using a tensiometer at 50 mm/s distraction. Mean knot execution time (mKET) measured in seconds (s), normalized KE time (nET=group mean/mKET), knot holding capacity, relative knot security (RKS), and PE (PE=RKS/nET) of the knots tied were computed and analyzed using paired t and analysis of variance. Variables included knot-tying session, technique and the training level. On completion of the study, junior residents (JR) averaged 51.72 seconds more, senior residents (SR) averaged 26.22 seconds more and attendings (ATT) averaged 19.17 seconds less to tie using CLT compared with the AST (F=40.52, P=0.0001). Across all levels, the CLT technique was taking 83.26 seconds on average to execute an IC knot compared with 59.08 seconds with AST method (t=2.784, P=0.015). Learning curves revealed that JR significantly improved mean KE times with the AST technique (first session vs. final session: 473.8 s vs. 55.9 s) compared with CLT (672.5 s vs. 107.6 s) across the sessions as compared with those in advanced levels of training. The RKS of knots executed by AST was significantly stronger (AST: 13.1 vs. 5.44 N, t=4.9, P=0.0001). The PE of knots executed using the CLT increased geometrically across training levels (JR: 1.35% SR: 5.58% ATT: 11.22%) whereas those of AST showed a linear trend (17.09%; 17

Spline curve matching with sparse knot sets

Treesearch

Sang-Mook Lee; A. Lynn Abbott; Neil A. Clark; Philip A. Araman

2004-01-01

This paper presents a new curve matching method for deformable shapes using two-dimensional splines. In contrast to the residual error criterion, which is based on relative locations of corresponding knot points such that is reliable primarily for dense point sets, we use deformation energy of thin-plate-spline mapping between sparse knot points and normalized local...

Methyl Transfer by Substrate Signaling from a Knotted Protein Fold

PubMed Central

Christian, Thomas; Sakaguchi, Reiko; Perlinska, Agata P.; Lahoud, Georges; Ito, Takuhiro; Taylor, Erika A.; Yokoyama, Shigeyuki; Sulkowska, Joanna I.; Hou, Ya-Ming

2017-01-01

Proteins with knotted configurations are restricted in conformational space relative to unknotted proteins. Little is known if knotted proteins have sufficient dynamics to communicate between spatially separated substrate-binding sites. In bacteria, TrmD is a methyl transferase that uses a knotted protein fold to catalyze methyl transfer from S-adenosyl methionine (AdoMet) to G37-tRNA. The product m1G37-tRNA is essential for life as a determinant to maintain protein synthesis reading-frame. Using an integrated approach of structure, kinetic, and computational analysis, we show here that the structurally constrained TrmD knot is required for its catalytic activity. Unexpectedly, the TrmD knot has complex internal movements that respond to AdoMet binding and signaling. Most of the signaling propagates the free energy of AdoMet binding to stabilize tRNA binding and to assemble the active site. This work demonstrates new principles of knots as an organized structure that captures the free energies of substrate binding to facilitate catalysis. PMID:27571175

Filtration of the classical knot concordance group and Casson-Gordon invariants

NASA Astrophysics Data System (ADS)

Kim, Taehee

2004-09-01

It is known that if every prime power branched cyclic cover of a knot in S(3) is a homology sphere, then the knot has vanishing Casson-Gordon invariants. We construct infinitely many examples of (topologically) non-slice knots in S(3) whose prime power branched cyclic covers are homology spheres. We show that these knots generate an infinite rank subgroup of scrf_{(1.0)}/scrf_{(1.5)} for which Casson-Gordon invariants vanish in Cochran-Orr-Teichner's filtration of the classical knot concordance group. As a corollary, it follows that Casson-Gordon invariants are not a complete set of obstructions to a second layer of Whitney disks.

Towards Employment: What Research Says About Support-to-Work in Relation to Psychiatric and Intellectual Disabilities.

PubMed

Lövgren, Veronica; Markström, Urban; Sauer, Lennart

2017-01-01

This article presents an overview of research about support-to-work in relation to psychiatric and intellectual disabilities. The overview shows that support-to-work services are multifaceted, and that work can be seen as a tool for individual rehabilitation or as a set of goals to achieve. Providers are presented with specific components, which are characterized by systematic, targeted, and individualized interventions. The overview illustrates a need for long-term engagement and cooperation of and between welfare services and agents within the labor market to dissolve the Gordian knot that the transition from welfare interventions to employment seems to be.

Constructing a polynomial whose nodal set is the three-twist knot 52

NASA Astrophysics Data System (ADS)

Dennis, Mark R.; Bode, Benjamin

2017-06-01

We describe a procedure that creates an explicit complex-valued polynomial function of three-dimensional space, whose nodal lines are the three-twist knot 52. The construction generalizes a similar approach for lemniscate knots: a braid representation is engineered from finite Fourier series and then considered as the nodal set of a certain complex polynomial which depends on an additional parameter. For sufficiently small values of this parameter, the nodal lines form the three-twist knot. Further mathematical properties of this map are explored, including the relationship of the phase critical points with the Morse-Novikov number, which is nonzero as this knot is not fibred. We also find analogous functions for other simple knots and links. The particular function we find, and the general procedure, should be useful for designing knotted fields of particular knot types in various physical systems.

Topological semimetals carrying arbitrary Hopf numbers: Fermi surface topologies of a Hopf link, Solomon's knot, trefoil knot, and other linked nodal varieties

NASA Astrophysics Data System (ADS)

Ezawa, Motohiko

2017-07-01

We propose a type of Hopf semimetal indexed by a pair of numbers (p ,q ) , where the Hopf number is given by p q . The Fermi surface is given by a preimage of the Hopf map, which consists of loops nontrivially linked for a nonzero Hopf number. The Fermi surface forms a torus link, whose examples are a Hopf link indexed by (1 ,1 ) , Solomon's knot (2 ,1 ) , a double Hopf link (2 ,2 ) , and a double trefoil knot (3 ,2 ) . We may choose p or q to be a half integer, where the Fermi surface is a torus knot, such as a trefoil knot (3 /2 ,1 ) . It is even possible to make the Hopf number an arbitrary rational number, where a semimetal whose Fermi surface forms open strings is generated.

Informed consent in Italy-traditional versus the law: a gordian knot.

PubMed

Turillazzi, Emanuela; Neri, Margherita; Riezzo, Irene; Frati, Paola; Fineschi, Vittorio

2014-08-01

Italian law no. 86 of 5 June 2012, which establishes a set of rules on the matter of breast implants, came into effect in July 2012. The law is at the center of a widespread and animated cultural debate that in recent years has been taking place in Italy. The fundamental prohibition imposed by the law concerns the age limit. Breast implants for exclusively aesthetic purposes are allowed only if the legal age (18 years) has been reached. This prohibition does not apply in cases of severe congenital malformations certified by a physician operating within the National Health Service or by a public health care institution. The legal imposition of an age limit raises a number of perplexities: one at a bioethical level and one that is strictly juridical. In fact, it is impossible to deal with this issue unless the wider debate concerning the self-determination and autonomy of underage patients in biomedical matters is considered. It appears, then, that the issue is again exclusively related to the peculiarity of cosmetic surgery, which when aimed at correcting "only" the pathologic experiences of self-image, does not acquire the dignity of therapy. If, however, the improvement of self-image serves to achieve a better psycho-emotional balance and favors the development of social relations undermined by evident physical defects, age restrictions can be disregarded. The authors believe the real risk is that the law imposed by the Italian state is based on assumptions and preformed value judgments. Furthermore, in the understanding of needs, legislation often is biased toward objective biophysical problems without attaching due importance to subjective psychological and social problems. While acknowledging the seriousness of the issue, the authors do not agree with the legislature's rigidity. However, plastic surgeons must form a plan for addressing the concerns about breast implants and evaluating whether they are appropriate for adolescents, taking into account the unique

Flexor Tendon Repair With Looped Suture: 1 Versus 2 Knots.

PubMed

Gil, Joseph A; Skjong, Christian; Katarincic, Julia A; Got, Christopher

2016-03-01

To assess the strength of flexor tendon repair with looped suture. We hypothesized that, after passing the intact looped suture in the desired repair configuration, splitting the loop and tying 2 independent knots would increase the strength of flexor tendon repair. Thirty-two flexor tendons were harvested and were sharply transected in zone II. The tendons were repaired with a 4-strand core suture repair using 3-0 looped nonabsorbable nylon suture. The harvested tendons were randomly assigned and repaired with either a 1- or a 2-knot construct. The repaired flexor tendons were fixed in a servohydraulic material testing system and were loaded to failure either with uniaxial tension or cyclically. The average force at failure was 43 N for the 1-knot repair and 28 N for the 2-knot repair. The mode of failure of 15 of the flexor tendon repairs that were cyclically loaded to failure was suture pull-out. The average number of cycles and force in cyclic testing that caused failure of flexor tendon repairs was 134 cycles and 31 N for tendons repaired with looped 3-0 suture tied with 1 knot and 94 cycles and 33 N for tendons repaired with looped 3-0 suture tied with 2 knots. Our hypothesis was disproved by the results of this study. This study suggests that, when using looped suture, tying 2 independent knots instead of tying a single knot does not increase the strength of the flexor tendon repair. Copyright © 2016 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Microgravity effects on fine motor skills: tying surgical knots during parabolic flight.

PubMed

Rafiq, Azhar; Hummel, Russ; Lavrentyev, Vladimir; Derry, William; Williams, David; Merrell, Ronald C

2006-08-01

The health provider on a space exploration mission cannot evacuate a patient to Earth. Contingency plans for medical intervention must be designed for autonomy. This study measured the effect of microgravity on performance of fine motor skills such as basic surgical tasks. Eight subjects, six with medical and two with non-medical backgrounds, were evaluated during parabolic microgravity flights aboard NASA's KC-135. We evaluated their skill in tying surgical knots on simulated skin made of silicone using standard techniques for minimally invasive surgery. LabView software was developed to archive forces applied to the laparoscopic tool handles during knot-tying. Studies were controlled for medication (ScopeDex) and the aircraft environment. All participants completed the tests successfully. The data indicated that increased force was applied to the instruments and knot quality decreased during flight compared with ground control sessions. Specific metrics of surgical task performance are essential in developing education modules for providers of medical care during exploration-class missions.

Notice of Release of ‘Truhart-NR’, a Root-knot Nematode Resistant, Pimento-type Pepper

USDA-ARS?s Scientific Manuscript database

The USDA has developed a high-yielding, pimento-type pepper (Capsicum annuum L.) cultivar that is highly resistant to root-knot nematodes. The new cultivar, Truhart-NR, is homozygous for the dominant N gene that conditions a high level of resistance to the southern root-knot nematode [Meloidogyne i...

Crystallization of Spätzle, a cystine-knot protein involved in embryonic development and innate immunity in Drosophila melanogaster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffmann, Anita; Neumann, Piotr; Schierhorn, Angelika

2008-08-01

Crystallization of the cystine-knot protein Spätzle occurred following serendipitous limited degradation of the pro-Spätzle propeptide during the crystallization experiment. The Spätzle protein is involved in both the definition of the dorsal–ventral axis during embryonic development and in the adult innate immune response. The disulfide-linked dimeric cystine-knot protein has been expressed as a proprotein in inclusion bodies in Escherichia coli and refolded in vitro by rapid dilution. Initial orthorhombic crystals that diffracted to 7 Å resolution were obtained after three months by the sitting-drop vapour-diffusion method. Optimization of the crystallization conditions resulted in orthorhombic crystals (space group P2{sub 1}2{sub 1}2{sub 1},more » with unit-cell parameters a = 53.0, b = 59.2, c = 62.5 Å) that diffracted to 2.8 Å resolution in-house. The small volume of the asymmetric unit indicated that it was not possible for the crystals to contain the complete pro-Spätzle dimer. Mass spectrometry, N-terminal sequencing and Western-blot analysis revealed that the crystals contained the C-terminal disulfide-linked cystine-knot dimer. Comparison of various crystallization experiments indicated that degradation of the N-terminal prodomain was dependent on the buffer conditions.« less

Arbuscular mycorrhizal fungi affect both penetration and further life stage development of root-knot nematodes in tomato.

PubMed

Vos, Christine; Geerinckx, Katleen; Mkandawire, Rachel; Panis, Bart; De Waele, Dirk; Elsen, Annemie

2012-02-01

The root-knot nematode Meloidogyne incognita poses a worldwide threat to agriculture, with an increasing demand for alternative control options since most common nematicides are being withdrawn due to environmental concerns. The biocontrol potential of arbuscular mycorrhizal fungi (AMF) against plant-parasitic nematodes has been demonstrated, but the modes of action remain to be unraveled. In this study, M. incognita penetration of second-stage juveniles at 4, 8 and 12 days after inoculation was compared in tomato roots (Solanum lycopersicum cv. Marmande) pre-colonized or not by the AMF Glomus mosseae. Further life stage development of the juveniles was also observed in both control and mycorrhizal roots at 12 days, 3 weeks and 4 weeks after inoculation by means of acid fuchsin staining. Penetration was significantly lower in mycorrhizal roots, with a reduction up to 32%. Significantly lower numbers of third- and fourth-stage juveniles and females accumulated in mycorrhizal roots, at a slower rate than in control roots. The results show for the first time that G. mosseae continuously suppresses root-knot nematodes throughout their entire early infection phase of root penetration and subsequent life stage development.

Knot Security of 5 Metric (USP 2) Sutures: Influence of Knotting Technique, Suture Material, and Incubation Time for 14 and 28 Days in Phosphate Buffered Saline and Inflamed Equine Peritoneal Fluid.

PubMed

Sanders, Ruth E; Kearney, Clodagh M; Buckley, Conor T; Jenner, Florien; Brama, Pieter A

2015-08-01

To evaluate knot security for 3 knot types created in 3 commonly used 5 metric suture materials incubated in physiological and pathological fluids. In vitro mechanical study. Knotted suture loops (n = 5/group). Loops of 3 different suture materials (glycolide/lactide copolymer; polyglactin 910; polydioxanone) were created around a 20 mm rod using 3 knot types (square [SQ], surgeon's [SK], and triple knot [TK]) and were tested to failure in distraction (6 mm/min) after tying (day 0) and after being incubated for 14 and 28 days in phosphate buffered saline (PBS) or inflamed peritoneal fluid. Failure load (N) and mode were recorded and compared. For polydioxanone, significant differences in force to knot failure were found between SQ and SK/TK but not between SK and TK. The force required to break all constructs increased after incubation in phosphate buffered saline (PBS). With glycolide/lactide copolymer no differences in force to knot failure were observed. With polyglactin 910, a significant difference between SQ and TK was observed, which was not seen between the other knot types. Incubation in inflamed peritoneal fluid caused a larger and more rapid decrease in force required to cause knot failure than incubation in PBS. Mechanical properties of suture materials have significant effects on knot security. For polydioxanone, SQ is insufficient to create a secure knot. Additional wraps above a SK confer extra stability in some materials, but this increase may not be clinically relevant or justifiable. Glycolide/lactide copolymer had excellent knot security. © Copyright 2015 by The American College of Veterinary Surgeons.

[Mechanical behaviour of three types of surgical knots using 4/0 monofilament].

PubMed

Gil Santos, Luis; Más-Estellés, Jorge; Salmerón Sánchez, Manuel; Barrios, Carlos

2012-01-01

To experimentally study the behaviour of 4 types of monofilament with 3 knotting techniques, very often used in surgery, employing mechanical tests. Four 4/0 monofilaments were chosen, two of nylon, and the other two of polypropylene. Three types of knot designs were made with each thread. The first design (D-S-S) consisted of a double half-knot (D) followed by one single (S) in the opposite direction, a third S in turn in the opposite direction. The configuration of the second design was D-S-D, and the third, S-S-D. A mechanical fracture test was performed by stretching the thread at a rate of 4N/s, the force and deformation being recorded at intervals of 100 ms. There was a decrease in the force and deformation in the tests on threads with knots compared to threads without knots. In all cases the rupture of the thread occurred in the knot area, presumably due to damage caused to the thread during the knotting process. The D-S-D knot had the greatest resistance with polypropylene threads, and S-S-D provided the greatest resistance with nylon threads Polypropylene threads, with D-S-D knots, should be more indicated to suture tissues that have to support great forces and with little deformation of the suture (e.g., tendons). Nylon threads, with S-S-D knots, would be better indicated for tissues that have to support smaller forces and that require greater elasticity (e.g., skin). Copyright © 2011 AEC. Published by Elsevier Espana. All rights reserved.

Are there p-adic knot invariants?

NASA Astrophysics Data System (ADS)

Morozov, A. Yu.

2016-04-01

We suggest using the Hall-Littlewood version of the Rosso-Jones formula to define the germs of p-adic HOMFLY-PT polynomials for torus knots [ m, n] as coefficients of superpolynomials in a q-expansion. In this form, they have at least the [ m, n] ↔ [ n, m] topological invariance. This opens a new possibility to interpret superpolynomials as p-adic deformations of HOMFLY polynomials and poses a question of generalizing to other knot families, which is a substantial problem for several branches of modern theory.

Synthesizing a Trefoil Knotted Block Copolymer via Ring-Expansion Strategy

DOE PAGES

Cao, Pengfei; Rong, Li-Han; Mangadlao, Joey; ...

2017-02-07

We synthesized a synthetic trefoil knotted poly(e-caprolatone) block-poly(L-lactide) (TK-PLA-b-PCL) via a ring expansion strategy from a trefoil knotted tin (Sn) initiator. Ring closing reaction between the bis-copper(I) templated phenanthro line complex and dibutyldimethoxytin results in a templated trefoil knotted initiator. Furthermore, the bis-copper(I) templated trefoil knotted poly(L-lactide) (TK-PLA) can be synthesized by ring-opening polymerization of L-lactide monomer, and decomplexation reaction of the templated TK-PLA will result in a geniune TK-PLA without constraint from the copper template. Subsequent insertion of e caprolactone in the bis-copper(I) templated TK-PLA forms the templated trefoil knotted block copolymer, i.e., TK-PLA-b-PCL, and the copper-free TK-PLA-b-PCL canmore » be obtained by decomplexation reaction. Finally, both TK-PLA and TK-PLA-b-PCL are analyzed by the 1 H NMR, FT-IR, UV-vis, DLS, and GPC.« less

Total curvature and total torsion of knotted random polygons in confinement

NASA Astrophysics Data System (ADS)

Diao, Yuanan; Ernst, Claus; Rawdon, Eric J.; Ziegler, Uta

2018-04-01

Knots in nature are typically confined spatially. The confinement affects the possible configurations, which in turn affects the spectrum of possible knot types as well as the geometry of the configurations within each knot type. The goal of this paper is to determine how confinement, length, and knotting affect the total curvature and total torsion of random polygons. Previously published papers have investigated these effects in the unconstrained case. In particular, we analyze how the total curvature and total torsion are affected by (1) varying the length of polygons within a fixed confinement radius and (2) varying the confinement radius of polygons with a fixed length. We also compare the total curvature and total torsion of groups of knots with similar complexity (measured as crossing number). While some of our results fall in line with what has been observed in the studies of the unconfined random polygons, a few surprising results emerge from our study, showing some properties that are unique due to the effect of knotting in confinement.

Knotted optical vortices in exact solutions to Maxwell's equations

NASA Astrophysics Data System (ADS)

de Klerk, Albertus J. J. M.; van der Veen, Roland I.; Dalhuisen, Jan Willem; Bouwmeester, Dirk

2017-05-01

We construct a family of exact solutions to Maxwell's equations in which the points of zero intensity form knotted lines topologically equivalent to a given but arbitrary algebraic link. These lines of zero intensity, more commonly referred to as optical vortices, and their topology are preserved as time evolves and the fields have finite energy. To derive explicit expressions for these new electromagnetic fields that satisfy the nullness property, we make use of the Bateman variables for the Hopf field as well as complex polynomials in two variables whose zero sets give rise to algebraic links. The class of algebraic links includes not only all torus knots and links thereof, but also more intricate cable knots. While the unknot has been considered before, the solutions presented here show that more general knotted structures can also arise as optical vortices in exact solutions to Maxwell's equations.

Multimedia article. The keys to the new laparoscopic world Thumbs up! knot and Tornado knot.

PubMed

Uchida, K; Haruta, N; Okajima, M; Matsuda, M; Yamamoto, M

2005-06-01

Most laparoscopic surgeons feel some anxiety when performing intracorporeal knotting with conventional techniques [1, 2]. Two factors contribute to this anxiety. The first is the necessity of recognizing three dimensions on a two-dimensional monitor. The conventional intracorporeal knotting techniques make loops by twisting the thread with a second pair of forceps. This necessitates cooperative movement of both hands, with the added difficulties of depth perception. Regular touch confirmations reduce problems with depth perception. However, touch confirmation is more complicated in laparoscopic surgery than in laparotomy. The second problem is that tied loops can come loose and escape the instruments, especially with hard thread. This is not only stressful but also increases operation time.

Hybrid Threat Center of Gravity Analysis: Cutting the Gordian Knot

DTIC Science & Technology

2016-04-04

U.S. Marine Corps General James Mattis summed this best when he stated that “we expect future enemies to look at the four approaches [Traditional...synthesis is what we call hybrid warfare.”15 15 James N. Mattis and Frank Hoffman, "Future...accoun tid=12686 (accessed August 16, 2015). Mattis , James N. and Frank Hoffman. "Future Warfare: The Rise of Hybrid wars." United States Naval

Untangling the Gordian knot of HIV, stress, and cognitive impairment.

PubMed

Valdez, Arielle N; Rubin, Leah H; Neigh, Gretchen N

2016-10-01

As individuals live longer with HIV, this "graying of the HIV epidemic" has introduced a new set of challenges including a growing number of age and inflammation-related diseases such as cardiovascular disease, type II diabetes, cancer, and dementia. The biological underpinnings of these complex and co-morbid diseases are not fully understood and become very difficult to disentangle in the context of HIV and aging. In the current review we examine the contributions and interactions of HIV, stress, and cognitive impairment and query the extent to which inflammation is the linchpin in these dynamic interactions. Given the inter-relatedness of stress, inflammatory mechanisms, HIV, and cognitive impairment, future work will either need to address multiple dimensions simultaneously or embrace the philosophy that breaking the aberrant cycle at any one point will subsequently remedy the other related systems and processes. Such a single-point intervention may be effective in early disease states, but after perpetuation of an aberrant cycle, adaptations in an attempt to internally resolve the issue will likely lead to the need for multifaceted interventions. Acknowledging that HIV, inflammation, and stress may interact with one another and collectively impact cognitive ability is an important step in fully understanding an individual's complete clinical picture and moving towards personalized medicine.

Untangling the Gordian Knot The Socio-Cultural Challenge of Syria

DTIC Science & Technology

2015-10-30

declining legitimacy through construction of traditions suggesting his leadership of modern Islam. 12 Ironically, Hamid II used Islamist language and...Nasserist leadership , and Damascus took up this role. 20 Ba’athist regimes, such as Syria, remained strong until the 1991-2003 time period. 21 The...Legion- style standards) with the most modern ideas of the time (e.g. mass politics, video technology and scientific propaganda). 23 In this method

Hybrid Threat Center of Gravity Analysis: Cutting the Gordian Knot

DTIC Science & Technology

2016-04-04

water avoids the heights … so an army avoids strengths and strikes weakness … water has no constant form.”1 - Sun Tzu Hybrid warfare is a topic...1 Sun Tzu , The Art of War, (Oxford University Press, London, 1963), 101. 2 Alba Iulia...and Boyer, Matthew. Vulnerability Assessment Method Pocket Guide: A Tool for Center of Gravity Analysis. RAND, 2014. Tzu , Sun . The Art of War

Equations on knot polynomials and 3d/5d duality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mironov, A.; Morozov, A.; ITEP, Moscow

2012-09-24

We briefly review the current situation with various relations between knot/braid polynomials (Chern-Simons correlation functions), ordinary and extended, considered as functions of the representation and of the knot topology. These include linear skein relations, quadratic Plucker relations, as well as 'differential' and (quantum) A-polynomial structures. We pay a special attention to identity between the A-polynomial equations for knots and Baxter equations for quantum relativistic integrable systems, related through Seiberg-Witten theory to 5d super-Yang-Mills models and through the AGT relation to the q-Virasoro algebra. This identity is an important ingredient of emerging a 3d- 5d generalization of the AGT relation. Themore » shape of the Baxter equation (including the values of coefficients) depend on the choice of the knot/braid. Thus, like the case of KP integrability, where (some, so far torus) knots parameterize particular points of the Universal Grassmannian, in this relation they parameterize particular points in the moduli space of many-body integrable systems of relativistic type.« less

Analysis of the tractive force pattern on a knot by force measurement during laparoscopic knot tying.

PubMed

Takayasu, Kenta; Yoshida, Kenji; Kinoshita, Hidefumi; Yoshimoto, Syunsuke; Oshiro, Osamu; Matsuda, Tadashi

2017-07-19

Quantifying surgical skills assists novice surgeons when learning operative techniques. We measured the interaction force at a ligation point and clarified the features of the force pattern among surgeons with different skill levels during laparoscopic knot tying. Forty-four surgeons were divided into three groups based on experience: 13 novice (0-5 years), 16 intermediate (6-15 years), and 15 expert (16-30 years). To assess the tractive force direction and volume during knot tying, we used a sensor that measures six force-torque values (x-axis: Fx, y-axis: Fy, z-axis: Fz, and xy-axis: Fxy) attached to a slit Penrose drain. All participants completed one double knot and five single knot sequences. We recorded completion time, force volume (FV), maximum force (MF), time over 1.5 N, duration of non-zero force, and percentage time when vertical force exceeded horizontal force (PTz). There was a significant difference between groups for completion time (p = 0.007); FV (total: p = 0.002; Fx: p = 0.004, Fy: p = 0.007, Fxy: p = 0.004, Fz: p < 0.001, Fxy/Fz: p = 0.003), MF (total: p = 0.004; Fx: p = 0.015, Fy: p = 0.035, Fxy: p = 0.009, Fz: p = 0.001, Fxy/Fz: p = 0.041); time over 1.5 N (p = 0.002); duration of non-zero force (p = 0.029); and PTz (p < 0.001). PTz showed the only significant difference comparing intermediates with experts (intermediates: 13.7 ± 9.0, experts: 4.9 ± 3.2; p < 0.001). We clarified the characteristics of the force pattern at the ligation point during suturing by surgeons with three levels of experience using a force measurement system. We revealed that both force volume and force direction differed depending on surgeons' skill level during knot tying. Copyright © 2017. Published by Elsevier Inc.

The roles of impact and inertia in the failure of a shoelace knot

NASA Astrophysics Data System (ADS)

Daily-Diamond, Christopher A.; Gregg, Christine E.; O'Reilly, Oliver M.

2017-04-01

The accidental untying of a shoelace while walking often occurs without warning. In this paper, we discuss the series of events that lead to a shoelace knot becoming untied. First, the repeated impact of the shoe on the floor during walking serves to loosen the knot. Then, the whipping motions of the free ends of the laces caused by the leg swing produce slipping of the laces. This leads to eventual runaway untangling of the knot. As demonstrated using slow-motion video footage and a series of experiments, the failure of the knot happens in a matter of seconds, often without warning, and is catastrophic. The controlled experiments showed that increasing inertial effects of the swinging laces leads to increased rate of knot untying, that the directions of the impact and swing influence the rate of failure, and that the knot structure has a profound influence on a knot's tendency to untie under cyclic impact loading.

Decay of helical and nonhelical magnetic knots

NASA Astrophysics Data System (ADS)

Candelaresi, Simon; Brandenburg, Axel

2011-07-01

We present calculations of the relaxation of magnetic field structures that have the shape of particular knots and links. A set of helical magnetic flux configurations is considered, which we call n-foil knots of which the trefoil knot is the most primitive member. We also consider two nonhelical knots; namely, the Borromean rings as well as a single interlocked flux rope that also serves as the logo of the Inter-University Centre for Astronomy and Astrophysics in Pune, India. The field decay characteristics of both configurations is investigated and compared with previous calculations of helical and nonhelical triple-ring configurations. Unlike earlier nonhelical configurations, the present ones cannot trivially be reduced via flux annihilation to a single ring. For the n-foil knots the decay is described by power laws that range form t-2/3 to t-1/3, which can be as slow as the t-1/3 behavior for helical triple-ring structures that were seen in earlier work. The two nonhelical configurations decay like t-1, which is somewhat slower than the previously obtained t-3/2 behavior in the decay of interlocked rings with zero magnetic helicity. We attribute the difference to the creation of local structures that contain magnetic helicity which inhibits the field decay due to the existence of a lower bound imposed by the realizability condition. We show that net magnetic helicity can be produced resistively as a result of a slight imbalance between mutually canceling helical pieces as they are being driven apart. We speculate that higher order topological invariants beyond magnetic helicity may also be responsible for slowing down the decay of the two more complicated nonhelical structures mentioned above.

Tolerance of a knotted near infrared fluorescent protein to random circular permutation

PubMed Central

Pandey, Naresh; Kuypers, Brianna E.; Nassif, Barbara; Thomas, Emily E.; Alnahhas, Razan N.; Segatori, Laura; Silberg, Jonathan J.

2016-01-01

Bacteriophytochrome photoreceptors (BphP) are knotted proteins that have been developed as near-infrared fluorescent protein (iRFP) reporters of gene expression. To explore how rearrangements in the peptides that interlace into the knot within the BphP photosensory core affect folding, we subjected iRFP to random circular permutation using an improved transposase mutagenesis strategy and screened for variants that fluoresce. We identified twenty seven circularly permuted iRFP that display biliverdin-dependent fluorescence in Escherichia coli. The variants with the brightest whole cell fluorescence initiated translation at residues near the domain linker and knot tails, although fluorescent variants were discovered that initiated translation within the PAS and GAF domains. Circularly permuted iRFP retained sufficient cofactor affinity to fluoresce in tissue culture without the addition of biliverdin, and one variant displayed enhanced fluorescence when expressed in bacteria and tissue culture. This variant displayed a similar quantum yield as iRFP, but exhibited increased resistance to chemical denaturation, suggesting that the observed signal increase arose from more efficient protein maturation. These results show how the contact order of a knotted BphP can be altered without disrupting chromophore binding and fluorescence, an important step towards the creation of near-infrared biosensors with expanded chemical-sensing functions for in vivo imaging. PMID:27304983

TOPICAL REVIEW: Knot theory and a physical state of quantum gravity

NASA Astrophysics Data System (ADS)

Liko, Tomás; Kauffman, Louis H.

2006-02-01

We discuss the theory of knots, and describe how knot invariants arise naturally in gravitational physics. The focus of this review is to delineate the relationship between knot theory and the loop representation of non-perturbative canonical quantum general relativity (loop quantum gravity). This leads naturally to a discussion of the Kodama wavefunction, a state which is conjectured to be the ground state of the gravitational field with positive cosmological constant. This review can serve as a self-contained introduction to loop quantum gravity and related areas. Our intent is to make the paper accessible to a wider audience that may include topologists, knot theorists, and other persons innocent of the physical background to this approach to quantum gravity.

Does infection by southern root-knot nematode influence development of Phytophthora blight in pepper?

USDA-ARS?s Scientific Manuscript database

The southern root-knot nematode, Meloidogyne incognita, and Phytophthora capsici, the causal agent of Phytophthora blight, are both important pathogens of pepper (Capsicum annuum L.) in the U.S. and worldwide. Although there is significant information in the literature about the responses of pepper...

360° virtual reality video for the acquisition of knot tying skills: A randomised controlled trial.

PubMed

Yoganathan, S; Finch, D A; Parkin, E; Pollard, J

2018-06-01

360° virtual reality (VR) video is an exciting and evolving field. Current technology promotes a totally immersive, 3-dimensional (3D), 360° experience anywhere in the world using simply a smart phone and virtual reality headset. The potential for its application in the field of surgical education is enormous. The aim of this study was to determine knot tying skills taught with a 360-degree VR video compared to conventional 2D video teaching. This trial was a prospective, randomised controlled study. 40 foundation year doctors (first year postgraduate) were randomised to either the 360-degree VR video (n = 20) or 2D video teaching (n = 20). Participants were given 15 min to watch their allocated video. Ability to tie a single handed reef knot was then assessed against a marking criteria developed for the Royal College of Surgeons, England, (RCSeng) Basic Surgical Skills (BSS) course, by a blinded assessor competent in knot tying. Each candidate then underwent further teaching using Peyton's four step model. Knot tying technique was then re-assessed. Knot tying scores were significantly better in the VR video teaching arm when compared with conventional (median knot score 5.0 vs 4.0 p = 0.04). When used in combination with face to face skills teaching this difference persisted (median knot score 9.5 vs 9.0 p = 0.01). More people in the VR arm constructed a complete reef knot than in the 2D arm following face to face teaching (17/20 vs 12/20). No difference between the groups existed in the time taken to construct a reef knot following video and teaching (median time 31.0s vs 30.5s p = 0.89). This study shows there is significant merit in the application of 360-degree VR video technology in surgical training, both as an independent teaching aid and when used as an adjunct to traditional face to face teaching. Copyright © 2018 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.

Thermodynamics of the pseudo-knot in helix 18 of 16S ribosomal RNA.

PubMed

Wojciechowska, Monika; Dudek, Marta; Trylska, Joanna

2018-04-01

A fragment of E. coli 16S rRNA formed by nucleotides 500 to 545 is termed helix 18. Nucleotides 505-507 and 524-526 form a pseudo-knot and its distortion affects ribosome function. Helix 18 isolated from the ribosome context is thus an interesting fragment to investigate the structural properties and folding of RNA with pseudo-knots. With all-atom molecular dynamics simulations, spectroscopic and gel electrophoresis experiments, we investigated thermodynamics of helix 18, with a focus on its pseudo-knot. In solution studies at ambient conditions we observed dimerization of helix 18. We proposed that the loop, containing nucleotides forming the pseudo-knot, interacts with another monomer of helix 18. The native dimer is difficult to break but introducing mutations in the pseudo-knot indeed assured a monomeric form of helix 18. Molecular dynamics simulations at 310 K confirmed the stability of the pseudo-knot but at elevated temperatures this pseudo-knot was the first part of helix 18 to lose the hydrogen bond pattern. To further determine helix 18 stability, we analyzed the interactions of helix 18 with short oligomers complementary to a nucleotide stretch containing the pseudo-knot. The formation of higher-order structures by helix 18 impacts hybridization efficiency of peptide nucleic acid and 2'-O methyl RNA oligomers. © 2018 Wiley Periodicals, Inc.

Tolerance of a Knotted Near-Infrared Fluorescent Protein to Random Circular Permutation.

PubMed

Pandey, Naresh; Kuypers, Brianna E; Nassif, Barbara; Thomas, Emily E; Alnahhas, Razan N; Segatori, Laura; Silberg, Jonathan J

2016-07-12

Bacteriophytochrome photoreceptors (BphP) are knotted proteins that have been developed as near-infrared fluorescent protein (iRFP) reporters of gene expression. To explore how rearrangements in the peptides that interlace into the knot within the BphP photosensory core affect folding, we subjected iRFPs to random circular permutation using an improved transposase mutagenesis strategy and screened for variants that fluoresce. We identified 27 circularly permuted iRFPs that display biliverdin-dependent fluorescence in Escherichia coli. The variants with the brightest whole cell fluorescence initiated translation at residues near the domain linker and knot tails, although fluorescent variants that initiated translation within the PAS and GAF domains were discovered. Circularly permuted iRFPs retained sufficient cofactor affinity to fluoresce in tissue culture without the addition of biliverdin, and one variant displayed enhanced fluorescence when expressed in bacteria and tissue culture. This variant displayed a quantum yield similar to that of iRFPs but exhibited increased resistance to chemical denaturation, suggesting that the observed increase in the magnitude of the signal arose from more efficient protein maturation. These results show how the contact order of a knotted BphP can be altered without disrupting chromophore binding and fluorescence, an important step toward the creation of near-infrared biosensors with expanded chemical sensing functions for in vivo imaging.

The Energy Landscape, Folding Pathways and the Kinetics of a Knotted Protein

PubMed Central

Prentiss, Michael C.; Wales, David J.; Wolynes, Peter G.

2010-01-01

The folding pathway and rate coefficients of the folding of a knotted protein are calculated for a potential energy function with minimal energetic frustration. A kinetic transition network is constructed using the discrete path sampling approach, and the resulting potential energy surface is visualized by constructing disconnectivity graphs. Owing to topological constraints, the low-lying portion of the landscape consists of three distinct regions, corresponding to the native knotted state and to configurations where either the N or C terminus is not yet folded into the knot. The fastest folding pathways from denatured states exhibit early formation of the N terminus portion of the knot and a rate-determining step where the C terminus is incorporated. The low-lying minima with the N terminus knotted and the C terminus free therefore constitute an off-pathway intermediate for this model. The insertion of both the N and C termini into the knot occurs late in the folding process, creating large energy barriers that are the rate limiting steps in the folding process. When compared to other protein folding proteins of a similar length, this system folds over six orders of magnitude more slowly. PMID:20617197

Variation in pin knot frequency in black walnut lumber cut from a small provenance/progeny test

Treesearch

Peter Y. S. Chen; Robert E. Bodkin; J. W. Van Sambeek

1995-01-01

This small study examined the frequency of knots (> 1 growth ring), pin knots (latent or suppressed buds), and pin knot clusters in 414 black walnut (Juglans nigra L.) lumber from 42 logs. 18 to 21 cm dbh, cut from a 14-year-old provenance/progeny test. Two boards from opposite sides of each log were analyzed for number of knots, pin knots, and...

Parity and cobordism of free knots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manturov, Vassily O

2012-02-28

A simple invariant is constructed which obstructs a free knot to be truncated. In particular, this invariant provides an obstruction to the truncatedness of curves immersed in two-dimensional surfaces. A curve on an oriented two-dimensional surface S{sub g} is referred to as truncated (null-cobordant) if there exists a three-dimensional manifold M with boundary S{sub g} and a smooth proper map of a two-disc to M such that the image of the boundary of the disc coincides with the curve. The problem of truncatedness for free knots is solved in this paper using the notion of parity recently introduced by themore » author. Bibliography: 12 titles.« less

Induction effects of torus knots and unknots

NASA Astrophysics Data System (ADS)

Oberti, Chiara; Ricca, Renzo L.

2017-09-01

Geometric and topological aspects associated with induction effects of field lines in the shape of torus knots/unknots are examined and discussed in detail. Knots are assumed to lie on a mathematical torus of circular cross-section and are parametrized by standard equations. The induced field is computed by direct integration of the Biot-Savart law. Field line patterns of the induced field are obtained and several properties are examined for a large family of knots/unknots up to 51 crossings. The intensity of the induced field at the origin of the reference system (center of the torus) is found to depend linearly on the number of toroidal coils and reaches maximum values near the boundary of the mathematical torus. New analytical estimates and bounds on energy and helicity are established in terms of winding number and minimum crossing number. These results find useful applications in several contexts when the source field is either vorticity, electric current or magnetic field, from vortex dynamics to astrophysics and plasma physics, where highly braided magnetic fields and currents are present.

DNA Knots: Theory and Experiments

NASA Astrophysics Data System (ADS)

Sumners, D. W.

Cellular DNA is a long, thread-like molecule with remarkably complex topology. Enzymes that manipulate the geometry and topology of cellular DNA perform many vital cellular processes (including segregation of daughter chromosomes, gene regulation, DNA repair, and generation of antibody diversity). Some enzymes pass DNA through itself via enzyme-bridged transient breaks in the DNA; other enzymes break the DNA apart and reconnect it to different ends. In the topological approach to enzymology, circular DNA is incubated with an enzyme, producing an enzyme signature in the form of DNA knots and links. By observing the changes in DNA geometry (supercoiling) and topology (knotting and linking) due to enzyme action, the enzyme binding and mechanism can often be characterized. This paper will discuss some personal research history, and the tangle model for the analysis of site-specific recombination experiments on circular DNA.

Using more of what trees provide - why not knots?

Treesearch

Matthew Bumgardner

2003-01-01

We are all familiar with furniture and paneling made from "knotty" pine. In fact, we expect pine to be knotty and such knots add a certain degree of warmness and authenticity. But have you ever wondered why there isn't more knotty oak furniture! Or knotty cherry cabinets? The fact is that most knot distortions and visual defects such as color streaks and...

Effect of Oryzalin and 1,1-Dimethylpiperidinium Chloride on Cotton and Tomato Roots Infected with the Root-knot Nematode, Meloidogyne incognita

PubMed Central

Orum, T. V.; Bartels, P. G.; McClure, M. A.

1979-01-01

Oryzalin (3,5-dinitro-N4,N4-dipropyl-sulfanilamide) and BAS 083 (l,l-dimethylpiperdinium chloride) reduced root-knot infection in tomato roots when respectively applied as a soil drench at 20 ppm and 10,000 ppm. Oryzalin reduced knot counts with various intervals between treatment and inoculation. BAS 083 reduced knot counts only when applied before inoculation. Oryzalin was shown not to be a contact nematicide, and BAS 083 was only a weak one. Neither compound reduced penetration by infective larvae. Postinfection reduction in knot counts by Oryzalin and BAS 083 resulted, in part, from activation of natural defense mechanisms of the host. Giant-cell development in cotton roots inoculated with nematodes was inhibited by Oryzalin. Lateral root development was inhibited by BAS 083. PMID:19305533

Potential of Leguminous Cover Crops in Management of a Mixed Population of Root-knot Nematodes (Meloidogyne spp.)

PubMed Central

Osei, Kingsley; Gowen, Simon R.; Pembroke, Barbara; Brandenburg, Rick L.; Jordan, David L.

2010-01-01

Root-knot nematode is an important pest in agricultural production worldwide. Crop rotation is the only management strategy in some production systems, especially for resource poor farmers in developing countries. A series of experiments was conducted in the laboratory with several leguminous cover crops to investigate their potential for managing a mixture of root-knot nematodes (Meloidogyne arenaria, M. incognita, M. javanica). The root-knot nematode mixture failed to multiply on Mucuna pruriens and Crotalaria spectabilis but on Dolichos lablab the population increased more than 2- fold when inoculated with 500 and 1,000 nematodes per plant. There was no root-galling on M. pruriens and C. spectabilis but the gall rating was noted on D. lablab. Greater mortality of juvenile root-knot nematodes occurred when exposed to eluants of roots and leaves of leguminous crops than those of tomato; 48.7% of juveniles died after 72 h exposure to root eluant of C. spectabilis. The leaf eluant of D. lablab was toxic to nematodes but the root eluant was not. Thus, different parts of a botanical contain different active ingredients or different concentrations of the same active ingredient. The numbers of root-knot nematode eggs that hatched in root exudates of M. pruriens and C. spectabilis were significantly lower (20% and 26%) than in distilled water, tomato and P. vulgaris root exudates (83%, 72% and 89%) respectively. Tomato lacks nematotoxic compounds found in M. pruriens and C. spectabilis. Three months after inoculating plants with 1,000 root-knot nematode juveniles the populations in pots with M. pruriens, C. spectabilis and C. retusa had been reduced by approximately 79%, 85% and 86% respectively; compared with an increase of 262% nematodes in pots with Phaseolus vulgaris. There was significant reduction of 90% nematodes in fallow pots with no growing plant. The results from this study demonstrate that some leguminous species contain compounds that either kill root-knot

Validation of Different Combination of Three Reversing Half-Hitches Alternating Posts (RHAPs) Effects on Arthroscopic Knot Integrity.

PubMed

Chong, Alexander Cm; Prohaska, Daniel J; Bye, Brian P

2017-05-01

With arthroscopic techniques being used, the importance of knot tying has been examined. Previous literature has examined the use of reversing half-hitches on alternating posts (RHAPs) on knot security. Separately, there has been research regarding different suture materials commonly used in the operating room. The specific aim of this study was to validate the effect of different stacked half-hitch configuration and different braided suture materials on arthroscopic knot integrity. Three different suture materials tied with five different RHAPs in arthroscopic knots were compared. A single load-to-failure test was performed and the mean ultimate clinical failure load was obtained. Significant knot holding strength improvement was found when one half-hitch was reversed as compared to baseline knot. When two of the half-hitches were reversed, there was a greater improvement with all knots having a mean ultimate clinical failure load greater than 150 newtons (N). Comparison of the suture materials demonstrated a higher mean ultimate clinical failure load when Force Fiber ® was used and at least one half-hitch was reversed. Knots tied with either Force Fiber ® or Orthocord ® showed 0% chance of knot slippage while knots tied with FiberWire ® or braided fishing line had about 10 and 30% knot slippage chances, respectively. A significant effect was observed in regards to both stacked half-hitch configuration and suture materials used on knot loop and knot security. Caution should be used with tying three RHAPs in arthroscopic surgery, particularly with a standard knot pusher and arthroscopic cannulas. The findings of this study indicated the importance of three RHAPs in performing arthroscopic knot tying and provided evidence regarding discrepancies of maximum clinical failure loads observed between orthopaedic surgeons, thereby leading to better surgical outcomes in the future.

Scaling behavior of knotted random polygons and self-avoiding polygons: Topological swelling with enhanced exponent.

PubMed

Uehara, Erica; Deguchi, Tetsuo

2017-12-07

We show that the average size of self-avoiding polygons (SAPs) with a fixed knot is much larger than that of no topological constraint if the excluded volume is small and the number of segments is large. We call it topological swelling. We argue an "enhancement" of the scaling exponent for random polygons with a fixed knot. We study them systematically through SAP consisting of hard cylindrical segments with various different values of the radius of segments. Here we mean by the average size the mean-square radius of gyration. Furthermore, we show numerically that the topological balance length of a composite knot is given by the sum of those of all constituent prime knots. Here we define the topological balance length of a knot by such a number of segments that topological entropic repulsions are balanced with the knot complexity in the average size. The additivity suggests the local knot picture.

Scaling behavior of knotted random polygons and self-avoiding polygons: Topological swelling with enhanced exponent

NASA Astrophysics Data System (ADS)

Uehara, Erica; Deguchi, Tetsuo

2017-12-01

We show that the average size of self-avoiding polygons (SAPs) with a fixed knot is much larger than that of no topological constraint if the excluded volume is small and the number of segments is large. We call it topological swelling. We argue an "enhancement" of the scaling exponent for random polygons with a fixed knot. We study them systematically through SAP consisting of hard cylindrical segments with various different values of the radius of segments. Here we mean by the average size the mean-square radius of gyration. Furthermore, we show numerically that the topological balance length of a composite knot is given by the sum of those of all constituent prime knots. Here we define the topological balance length of a knot by such a number of segments that topological entropic repulsions are balanced with the knot complexity in the average size. The additivity suggests the local knot picture.

LONG-TERM MONITORING OF THE DYNAMICS AND PARTICLE ACCELERATION OF KNOTS IN THE JET OF CENTAURUS A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodger, J. L.; Hardcastle, M. J.; Croston, J. H., E-mail: j.l.goodger@herts.ac.u, E-mail: m.j.hardcastle@herts.ac.u, E-mail: J.Croston@soton.ac.u

2010-01-01

We present new and archival multi-frequency radio and X-ray data for Centaurus A obtained over almost 20 years at the Very Large Array and with Chandra, with which we measure the X-ray and radio spectral indices of jet knots, flux density variations in the jet knots, polarization variations, and proper motions. We compare the observed properties with current knot formation models and particle acceleration mechanisms. We rule out impulsive particle acceleration as a formation mechanism for all of the knots as we detect the same population of knots in all of the observations, and we find no evidence of extrememore » variability in the X-ray knots. We find that the most likely mechanism for all the stationary knots is a collision resulting in a local shock followed by a steady state of prolonged, stable particle acceleration, and X-ray synchrotron emission. In this scenario, the X-ray-only knots have radio counterparts that are too faint to be detected, while the radio-only knots are due to weak shocks where no particles are accelerated to X-ray emitting energies. Although the base knots are prime candidates for reconfinement shocks, the presence of a moving knot in this vicinity and the fact that there are two base knots are hard to explain in this model. We detect apparent motion in three knots; however, their velocities and locations provide no conclusive evidence for or against a faster moving 'spine' within the jet. The radio-only knots, both stationary and moving, may be due to compression of the fluid.« less

Knot invariants and M-theory: Proofs and derivations

NASA Astrophysics Data System (ADS)

Errasti Díez, Verónica

2018-01-01

We construct two distinct yet related M-theory models that provide suitable frameworks for the study of knot invariants. We then focus on the four-dimensional gauge theory that follows from appropriately compactifying one of these M-theory models. We show that this theory has indeed all required properties to host knots. Our analysis provides a unifying picture of the various recent works that attempt an understanding of knot invariants using techniques of four-dimensional physics. This is a companion paper to K. Dasgupta, V. Errasti Díez, P. Ramadevi, and R. Tatar, Phys. Rev. D 95, 026010 (2017), 10.1103/PhysRevD.95.026010, covering all but Sec. III C. It presents a detailed mathematical derivation of the main results there, as well as additional material. Among the new insights, those related to supersymmetry and the topological twist are highlighted. This paper offers an alternative, complementary formulation of the contents in the first paper, but is self-contained and can be read independently.

Knot, heartwood, and sapwood extractives related to VOCs from drying southern pine lumber

Treesearch

Leonard L. Ingram; M. Curry Templeton; G. Wayne McGraw; Richard W. Hemingway

2000-01-01

The presence of knots or heartwood influences the amount and composition of volatile organic compound (VOC) emissions associated with drying of southern pine lumber. Experimental kiln charges of lumber containing 0 to 5% of knot volume gave VOC emissions ranging from 2.86 to 4.25 lb of carbonldry ton of wood. Studies of emissions from sapwood and knots showed that...

The "wilderness knot"

Treesearch

Haydn G. Washington

2007-01-01

The word “wilderness” is beset by a tangle of meanings. This “knot” is made of five strands: philosophical, political, cultural, justice and exploitation. Wilderness has a unique philosophical position—being disliked by both Modernism and Postmodernism. Eight key criticisms of wilderness are identified, and two different meanings discussed—“wasteland” and “large...

Wall-crossing invariants: from quantum mechanics to knots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galakhov, D., E-mail: galakhov@itep.ru, E-mail: galakhov@physics.rutgers.edu; Mironov, A., E-mail: mironov@lpi.ru; Morozov, A., E-mail: morozov@itep.ru

2015-03-15

We offer a pedestrian-level review of the wall-crossing invariants. The story begins from the scattering theory in quantum mechanics where the spectrum reshuffling can be related to permutations of S-matrices. In nontrivial situations, starting from spin chains and matrix models, the S-matrices are operatorvalued and their algebra is described in terms of R- and mixing (Racah) U-matrices. Then the Kontsevich-Soibelman (KS) invariants are nothing but the standard knot invariants made out of these data within the Reshetikhin-Turaev-Witten approach. The R and Racah matrices acquire a relatively universal form in the semiclassical limit, where the basic reshufflings with the change ofmore » moduli are those of the Stokes line. Natural from this standpoint are matrices provided by the modular transformations of conformal blocks (with the usual identification R = T and U = S), and in the simplest case of the first degenerate field (2, 1), when the conformal blocks satisfy a second-order Shrödinger-like equation, the invariants coincide with the Jones (N = 2) invariants of the associated knots. Another possibility to construct knot invariants is to realize the cluster coordinates associated with reshufflings of the Stokes lines immediately in terms of check-operators acting on solutions of the Knizhnik-Zamolodchikov equations. Then the R-matrices are realized as products of successive mutations in the cluster algebra and are manifestly described in terms of quantum dilogarithms, ultimately leading to the Hikami construction of knot invariants.« less

Confirming the nature of the knot near the pulsar B1951+32

NASA Astrophysics Data System (ADS)

Zyuzin, D. A.; Shibanov, Yu A.; Pavlov, G. G.; Danilenko, A. A.

2017-12-01

The energetic and fast-moving radio and γ-ray pulsar B1951+32 is associated with the supernova remnant CTB 80. It powers a complex pulsar wind nebula detected in the radio, Hα and X-rays (Moon et al 2004 ApJ 610 L33). A puzzling optical knot was detected about 0″.5 from the pulsar in the optical and near-IR (Moon et al 2004 ApJ 610 L33; Hester 2000 Bulletin of the AAS 32 1542). It is reminiscent of the unique “inner optical knot” located 0″.6 from the Crab pulsar. Until now there has been no evidence that B1951+32 knot is indeed associated with the pulsar. We observed the pulsar field with the Gemini-North telescope in 2016 to check the association. We performed first near-IR high spatial resolution imaging in the K s band using the NIRI+Altair instrument and deep optical imaging in the gr bands using the GMOS instrument. Our observations showed that the current knot position is shifted by ≈ 0″.6 from the position measured with the HST in 1997. This is consistent with the known pulsar proper motion and is direct evidence of the pulsar-knot connection. We compared the spectral energy distribution of the knot emission with that of the Crab knot. Possible implications of the results are discussed.

Effects of horseshoe crab harvest in delaware bay on red knots: Are harvest restrictions working?

USGS Publications Warehouse

Niles, L.J.; Bart, J.; Sitters, H.P.; Dey, A.D.; Clark, K.E.; Atkinson, P.W.; Baker, Allan J.; Bennett, K.A.; Kalasz, K.S.; Clark, N.A.; Clark, J.; Gillings, S.; Gates, A.S.; Gonzalez, P.M.; Hernandez, D.E.; Minton, C.D.T.; Morrison, R.I.G.; Porter, R.R.; Ross, R.K.; Veitch, C.R.

2009-01-01

Each May, red knots (Calidris canutus rufa) congregate in Delaware Bay during their northward migration to feed on horseshoe crab eggs (Limulus polyphemus) and refuel for breeding in the Arctic. During the 1990s, the Delaware Bay harvest of horseshoe crabs for bait increased 10-fold, leading to a more than 90% decline in the availability of their eggs for knots. The proportion of knots achieving weights of more than 180 grams by 26-28 May, their main departure period, dropped from 0.6-0.8 to 0.14-0.4 over 1997-2007. During the same period, the red knot population stopping in Delaware Bay declined by more than 75%, in part because the annual survival rate of adult knots wintering in Tierra del Fuego declined. Despite restrictions, the 2007 horseshoe crab harvest was still greater than the 1990 harvest, and no recovery of knots was detectable. We propose an adaptive management strategy with recovery goals and annual monitoring that, if adopted, will both allow red knot and horseshoe crab populations to recover and permit a sustainable harvest of horseshoe crabs.

DYNAMICS OF VERTICAL THREADS AND DESCENDING KNOTS IN A HEDGEROW PROMINENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chae, Jongchul

The existence and behavior of vertical fine structures of plasma-threads and knots-are a significant observational clue to understanding the magnetic structure and dynamics of quiescent prominences on the quiet Sun. Based on the equation of motion in ideal MHD, we reason that the non-hydrostatic support of plasma against gravity in general requires either the motion of plasma with a high value of downward acceleration (dynamical support) or the role of horizontal magnetic fields (magnetic support). By carefully tracking the motion of several bright threads seen in a hedgerow prominence observed by the Solar Optical Telescope aboard Hinode, we confirm thatmore » these threads are essentially static and stable, which negates the dynamic support. The application of the Kippenhahn-Schlueter solution suggests that they may be supported by sagged magnetic field lines with a sag angle of about 43{sup 0}. We also track several bright descending knots and find that their descending speeds range from 10 to 30 km s{sup -1}, with a mean value of 16 km s{sup -1}, and their vertical accelerations from -0.10 to 0.10 km s{sup -2}, with a mean of practically zero. This finding suggests that these knots are basically supported by horizontal magnetic fields against gravity even when they descend, and the complex variations of their descending speeds should be attributed to small imbalances between gravity and the force of magnetic tension. Furthermore, some knots are observed to impulsively get accelerated downward from time to time. We conjecture that these impulsive accelerations are a result of magnetic reconnection and the subsequent interchange of magnetic configuration between a knot and its surrounding structure. It is proposed that this process of reconnection and interchange not only initiates the descending motion of the knots, but also allows knots to keep falling long distance through the medium permeated by horizontal magnetic fields.« less

A silicone rubber mould of the heart.

PubMed

Torrent-Guasp, F F; Whimster, W F; Redmann, K

1997-04-01

The macroscopical structure of the ventricular myocardium has been an unsolved problem since the XVIth century, when Anatomy started as an authentic science. Since then the spatial organization of the myocardial fibres has represented, as Pettigrew says, "an arrangement so unusual and perplexing, that it has long been considered as forming a kind of Gordian knot in Anatomy. Of the complexity of the arrangement I need not speak further than to say that Vesalius, Albinus, Haller and De Blainville, all confessed their-inability to unravel it". What is shown in the present paper is the result of an anatomical work, developed over 43 years, by means of which it has been shown that the ventricular myocardial mass consists of a band, curled in a helical way, which extends from the pulmonary artery to the aorta. This is illustrated by a silicone rubber model cast from an actual unrolled myocardial band.

A "Firework" of H2 Knots in the Planetary Nebula NGC 7293 (The Helix Nebula)

NASA Astrophysics Data System (ADS)

Matsuura, M.; Speck, A. K.; McHunu, B. M.; Tanaka, I.; Wright, N. J.; Smith, M. D.; Zijlstra, A. A.; Viti, S.; Wesson, R.

2009-08-01

We present a deep and wide field-of-view (4' × 7') image of the planetary nebula (PN) NGC 7293 (the Helix Nebula) in the 2.12 μm H2 v = 1 → 0 S(1) line. The excellent seeing (0farcs4) at the Subaru Telescope, allows the details of cometary knots to be examined. The knots are found at distances of 2farcm2-6farcm4 from the central star (CS). At the inner edge and in the inner ring (up to 4farcm5 from the CS), the knot often show a "tadpole" shape, an elliptical head with a bright crescent inside and a long tail opposite to the CS. In detail, there are variations in the tadpole shapes, such as narrowing tails, widening tails, meandering tails, or multipeaks within a tail. In the outer ring (4farcm5-6farcm4 from the CS), the shapes are more fractured, and the tails do not collimate into a single direction. The transition in knot morphology from the inner edge to the outer ring is clearly seen. The number density of knots governs the H2 surface brightness in the inner ring: H2 exists only within the knots. Possible mechanisms which contribute to the shaping of the knots are discussed, including photoionization and streaming motions. A plausible interpretation of our images is that inner knots are being overrun by a faster wind, but that this has not (yet) reached the outer knots. Based on H2 formation and destruction rates, H2 gas can survive in knots from formation during the late asymptotic giant branch phase throughout the PN phase. These observations provide new constraints on the formation and evolution of knots, and on the physics of molecular gas embedded within ionized gas. Based on data taken with the Subaru Telescope, National Astronomical Observatory of Japan (proposal ID S07B-054).

Novel application of an established technique for removing a knotted ureteric stent.

PubMed

Tempest, Heidi; Turney, Ben; Kumar, Sunil

2011-04-13

This report describes a case whereby a ureteric stent became knotted during removal and lodged within the upper ureter. The authors describe a novel minimally invasive technique to remove the knotted ureteric stent using the holmium laser.

A 'FIREWORK' OF H{sub 2} KNOTS IN THE PLANETARY NEBULA NGC 7293 (THE HELIX NEBULA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuura, M.; Speck, A. K.; McHunu, B. M.

2009-08-01

We present a deep and wide field-of-view (4' x 7') image of the planetary nebula (PN) NGC 7293 (the Helix Nebula) in the 2.12 {mu}m H{sub 2} v = 1 {yields} 0 S(1) line. The excellent seeing (0.''4) at the Subaru Telescope, allows the details of cometary knots to be examined. The knots are found at distances of 2.'2-6.'4 from the central star (CS). At the inner edge and in the inner ring (up to 4.'5 from the CS), the knot often show a 'tadpole' shape, an elliptical head with a bright crescent inside and a long tail opposite tomore » the CS. In detail, there are variations in the tadpole shapes, such as narrowing tails, widening tails, meandering tails, or multipeaks within a tail. In the outer ring (4.'5-6.'4 from the CS), the shapes are more fractured, and the tails do not collimate into a single direction. The transition in knot morphology from the inner edge to the outer ring is clearly seen. The number density of knots governs the H{sub 2} surface brightness in the inner ring: H{sub 2} exists only within the knots. Possible mechanisms which contribute to the shaping of the knots are discussed, including photoionization and streaming motions. A plausible interpretation of our images is that inner knots are being overrun by a faster wind, but that this has not (yet) reached the outer knots. Based on H{sub 2} formation and destruction rates, H{sub 2} gas can survive in knots from formation during the late asymptotic giant branch phase throughout the PN phase. These observations provide new constraints on the formation and evolution of knots, and on the physics of molecular gas embedded within ionized gas.« less

Dynamics of knotted flexible loops settling under a constant force in a viscous fluid

NASA Astrophysics Data System (ADS)

Gruziel, Magdalena; Thyagarajan, Krishnan; Dietler, Giovanni; Szymczak, Piotr; Ekiel-Jezewska, Maria

2017-11-01

Sedimenting chains of metal beads knotted to a topology of a torus knot tend to stabilize in the form of extended, flat, tightly interwound loops. In this configuration they perform an oscillatory motion of the loops swirling periodically around each other. Stokesian dynamics simulations of elastic fibers confirm the long-lasting character of the traveling wave-like swirling motion and show also the accompanying rotation of the system. Moreover, the periodic motion shows striking resemblance to the stable solutions for the evolution of vortices of torus knot topology. Using the results of the simulations we study the dependence of the frequencies and sedimentation velocities on the length of the fiber. We also notice the dependence of the knot dynamics on the bending stiffness of the fiber and the knot rank. NCN-2015/19/D/ST8/03199.

Novel application of an established technique for removing a knotted ureteric stent

PubMed Central

Tempest, Heidi; Turney, Ben; Kumar, Sunil

2011-01-01

This report describes a case whereby a ureteric stent became knotted during removal and lodged within the upper ureter. The authors describe a novel minimally invasive technique to remove the knotted ureteric stent using the holmium laser. PMID:22701009

Evaluation of 5 knots and 2 suture materials for arthroscopic rotator cuff repair: very strong sutures can still slip.

PubMed

Abbi, Gaurav; Espinoza, Luis; Odell, Timothy; Mahar, Andrew; Pedowitz, Robert

2006-01-01

To compare a standard suture material with a newer material using multiple arthroscopic knot configurations and to evaluate the biomechanical performance of a new sliding-locking knot compared with 4 surgical standards. Controlled laboratory study. Five knots were evaluated (Weston, Tennessee, Duncan, SMC, and the new San Diego knot) using 2 suture materials, No. 2 Ethibond (Ethicon, Somerville, NJ) or No. 2 Fiberwire (Arthrex, Naples, FL). Eight samples were tested for each knot-suture configuration. Samples were pretensioned to 10 N and then loaded from 10 to 45 N for 1,000 cycles. Intact knots were loaded to failure. Fiberwire had significantly higher load-to-failure (276 +/- 24 N) compared with Ethibond (111 +/- 13 N) (P < .001), although there was no significant difference as a function of knot configuration. Of the 40 Fiberwire knots, 3 failed by early slippage during cyclic loading and 8 slipped at very low tension during load-to-failure. None of the Ethibond knots and none of the San Diego knots failed by early slippage. Surface characteristics and suture construction affect the tendency for knot slippage. Surgeons should understand the impact of handling characteristics, frictional properties, and ultimate failure load when selecting suture materials and knots for arthroscopic repair.

Truhart-NR, A Root-knot Nematode Resistant, Pimento-type Pepper Cultivar

USDA-ARS?s Scientific Manuscript database

Efforts to develop a high-yielding, pimento-type pepper (Capsicum annuum L.) cultivar that is highly resistant to root-knot nematodes were completed with the official release of Truhart-NR on October 20, 2009. The new cultivar is homozygous for the dominant N gene that conditions a high level of re...

‘Truhart-NR’, A Root-knot Nematode Resistant, Pimento-type Pepper

USDA-ARS?s Scientific Manuscript database

Efforts to develop a high-yielding, pimento-type pepper (Capsicum annuum L.) cultivar that is highly resistant to root-knot nematodes were completed with the official release of Truhart-NR on October 20, 2009. The new cultivar is homozygous for the dominant N gene that conditions a high level of re...

Freely Expanding Knots of X-Ray-emitting Ejecta in Kepler’s Supernova Remnant

NASA Astrophysics Data System (ADS)

Sato, Toshiki; Hughes, John P.

2017-08-01

We report measurements of proper motion, radial velocity, and elemental composition for 14 compact X-ray-bright knots in Kepler’s supernova remnant (SNR) using archival Chandra data. The knots with the highest speed show both large proper motions (μ ˜ 0.″11-0.″14 yr-1) and high radial velocities (v ˜ 8700-10,020 km s-1). For these knots the estimated space velocities (9100 km s-1 ≲ v 3D ≲ 10,400 km s-1) are similar to the typical Si velocity seen in supernovae (SNe) Ia near maximum light. High-speed ejecta knots appear only in specific locations and are morphologically and kinematically distinct from the rest of the ejecta. The proper motions of five knots extrapolate back over the age of Kepler’s SNR to a consistent central position. This new kinematic center agrees well with previous determinations, but is less subject to systematic errors and denotes a location about which several prominent structures in the remnant display a high degree of symmetry. These five knots are expanding at close to the free expansion rate (expansion indices of 0.75 ≲ m ≲ 1.0), which we argue indicates either that they were formed in the explosion with a high density contrast (more than 100 times the ambient density) or that they have propagated through regions of relatively low density (n H < 0.1 cm-3) in the ambient medium. X-ray spectral analysis shows that the undecelerated knots have high Si and S abundances, a lower Fe abundance, and very low O abundance, pointing to an origin in the partial Si-burning zone, which occurs in the outer layer of the exploding white dwarf for models of SNe Ia. Other knots show lower speeds and expansion indices consistent with decelerated ejecta knots or features in the ambient medium overrun by the forward shock. Our new accurate location for the explosion site has well-defined positional uncertainties, allowing for a great reduction in the area to be searched for faint surviving donor stars under non-traditional single

High finesse microfiber knot resonators made from double-ended tapered fibers.

PubMed

Xiao, Limin; Birks, T A

2011-04-01

We fabricated optical microfiber knot resonators from thin tapered fibers (diameter down to 1 μm) linked to untapered fiber at both ends. We demonstrated a finesse of about 100, over twice as high as previously reported for microfiber resonators. Low-loss encapsulation of microfiber knot resonators in hydrophobic silica aerogel was also investigated.

Tightening slip knots in raw and degummed silk to increase toughness without losing strength.

PubMed

Pantano, Maria F; Berardo, Alice; Pugno, Nicola M

2016-02-12

Knots are fascinating topological elements, which can be found in both natural and artificial systems. While in most of the cases, knots cannot be loosened without breaking the strand where they are tightened, herein, attention is focused on slip or running knots, which on the contrary can be unfastened without compromising the structural integrity of their hosting material. Two different topologies are considered, involving opposite unfastening mechanisms, and their influence on the mechanical properties of natural fibers, as silkworm silk raw and degummed single fibers, is investigated and quantified. Slip knots with optimized shape and size result in a significant enhancement of fibers energy dissipation capability, up to 300-400%, without affecting their load bearing capacity.

Tightening slip knots in raw and degummed silk to increase toughness without losing strength

PubMed Central

Pantano, Maria F.; Berardo, Alice; Pugno, Nicola M.

2016-01-01

Knots are fascinating topological elements, which can be found in both natural and artificial systems. While in most of the cases, knots cannot be loosened without breaking the strand where they are tightened, herein, attention is focused on slip or running knots, which on the contrary can be unfastened without compromising the structural integrity of their hosting material. Two different topologies are considered, involving opposite unfastening mechanisms, and their influence on the mechanical properties of natural fibers, as silkworm silk raw and degummed single fibers, is investigated and quantified. Slip knots with optimized shape and size result in a significant enhancement of fibers energy dissipation capability, up to 300–400%, without affecting their load bearing capacity. PMID:26868855

Freely Expanding Knots of X-Ray-emitting Ejecta in Kepler’s Supernova Remnant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Toshiki; Hughes, John P., E-mail: toshiki@astro.isas.jaxa.jp, E-mail: jph@physics.rutgers.edu

We report measurements of proper motion, radial velocity, and elemental composition for 14 compact X-ray-bright knots in Kepler’s supernova remnant (SNR) using archival Chandra data. The knots with the highest speed show both large proper motions ( μ ∼ 0.″11–0.″14 yr{sup −1}) and high radial velocities ( v ∼ 8700–10,020 km s{sup −1}). For these knots the estimated space velocities (9100 km s{sup −1} ≲ v {sub 3D} ≲ 10,400 km s{sup −1}) are similar to the typical Si velocity seen in supernovae (SNe) Ia near maximum light. High-speed ejecta knots appear only in specific locations and are morphologically andmore » kinematically distinct from the rest of the ejecta. The proper motions of five knots extrapolate back over the age of Kepler’s SNR to a consistent central position. This new kinematic center agrees well with previous determinations, but is less subject to systematic errors and denotes a location about which several prominent structures in the remnant display a high degree of symmetry. These five knots are expanding at close to the free expansion rate (expansion indices of 0.75 ≲ m ≲ 1.0), which we argue indicates either that they were formed in the explosion with a high density contrast (more than 100 times the ambient density) or that they have propagated through regions of relatively low density ( n {sub H} < 0.1 cm{sup −3}) in the ambient medium. X-ray spectral analysis shows that the undecelerated knots have high Si and S abundances, a lower Fe abundance, and very low O abundance, pointing to an origin in the partial Si-burning zone, which occurs in the outer layer of the exploding white dwarf for models of SNe Ia. Other knots show lower speeds and expansion indices consistent with decelerated ejecta knots or features in the ambient medium overrun by the forward shock. Our new accurate location for the explosion site has well-defined positional uncertainties, allowing for a great reduction in the area to be searched

Knotted versus knotless suture bridge repair of the achilles tendon insertion: a biomechanical study.

PubMed

Cox, Joseph T; Shorten, Peter L; Gould, Gregory C; Markert, Ronald J; Barnett, Michael D; Laughlin, Richard T

2014-11-01

Surgical treatment of insertional Achilles tendinopathy often involves detachment and debridement of the Achilles tendon insertion. A recent study has shown that knotted suture bridge fixation of the Achilles to the calcaneus is biomechanically superior to single-row fixation, but there is an absence of literature on the use of different suture bridge constructs to repair the Achilles tendon. There will be no significant difference in the load to failure, mode of failure, tendon strain, tendon stiffness, repair site gapping, or footprint size when comparing knotted suture bridge repair to knotless suture bridge repair of the Achilles tendon after detachment for insertional Achilles tendinopathy. Controlled laboratory study. A single specimen from each pair of 10 cadaveric Achilles tendons was randomized to 1 of 2 Achilles insertion repair groups: knotted (n = 10) or knotless (n = 10) suture bridge repair. Repaired footprint size was measured, and then cyclic testing from 10 to 100 N for 2000 cycles was performed. This was followed by measurement of tendon strain, repair site displacement, load to failure, and tendon stiffness. The knotted suture bridge repair had a significantly higher load to failure compared with the knotless suture bridge (mean ± SD, 317.8 ± 93.6 N vs 196.1 ± 12.1 N, respectively; P = .001). All constructs failed at the tendon-suture interface. Tendon strain after cyclic testing was significantly greater in the knotless (1.20 ± 1.05) compared with the knotted (0.39 ± 0.4) suture repair groups (P = .011). There was no significant difference in footprint size between the knotted (230.3 ± 63.3 mm(2)) and knotless (248.5 ± 48.8 mm(2)) groups (P = .40). There was also no significant difference in stiffness (knotted = 76.4 ± 8.0 N/mm; knotless = 69.6 ± 10.9 N/mm; P = .17) and repair site displacement after cyclic testing (knotted = 2.8 ± 1.2 mm; knotless = 3.6 ± 1.1 mm; P = .17). During suture bridge repair of the Achilles tendon after

In vitro and in situ characterization of arthroscopic loop security and knot security of braided polyblend sutures: a biomechanical study.

PubMed

Armstrong, Lucas C; Chong, Alexander; Livermore, Ryan W; Prohaska, Daniel J; Doyon, Amanda N; Wooley, Paul H

2015-04-01

We conducted a study to evaluate biomechanical performance during destructive testing of several different suture materials in various arthroscopic knot configurations under both in vitro and in situ conditions. Surgeons of different levels of experience tied the knots. Three different arthroscopic knots (static surgeon's, Weston, Tennessee slider) with 3 reverse half-hitches on alternating posts were tested using Fiberwire, ForceFiber, Orthocord, and Ultrabraid suture materials under both in vitro and in situ (blood plasma at 37°C) conditions. Three surgeons of different experience levels tied the knots on a post 30 mm in circumference. A single load-to-failure test was performed. There were no significant in vitro-in situ differences for Ultrabraid in the different knot configurations or with the different experience levels. Surgeon B (intermediate experience) showed no significant differences between test conditions for any knot configuration or suture material. With Tennessee slider knots, surgeon C (least experience) showed significantly lower clinical failure load under both test conditions and had a higher percentage of complete knot slippage. Surgeon B had no knot slippage with use of Fiberwire. Both the aqueous environment and the surgeon's familiarity with certain knots have an effect on knot security.

HOMFLYPT polynomial is the best quantifier for topological cascades of vortex knots

NASA Astrophysics Data System (ADS)

Ricca, Renzo L.; Liu, Xin

2018-02-01

In this paper we derive and compare numerical sequences obtained by adapted polynomials such as HOMFLYPT, Jones and Alexander-Conway for the topological cascade of vortex torus knots and links that progressively untie by a single reconnection event at a time. Two cases are considered: the alternate sequence of knots and co-oriented links (with positive crossings) and the sequence of two-component links with oppositely oriented components (negative crossings). New recurrence equations are derived and sequences of numerical values are computed. In all cases the adapted HOMFLYPT polynomial proves to be the best quantifier for the topological cascade of torus knots and links.

Cotton Cultivar Response to Root-Knot Nematodes in Two Tillage Regimes, 2008

USDA-ARS?s Scientific Manuscript database

Six cotton cultivars were evaluated for yield response to the root-knot nematode in a naturally infested field at E. V. Smith Research and Extension Center, near Shorter, Alabama. The field had a long history of root-knot nematode infestation, and the soil type was classified as a sandy loam. Plots ...

Ferromagnetic Switching of Knotted Vector Fields in Liquid Crystal Colloids.

PubMed

Zhang, Qiaoxuan; Ackerman, Paul J; Liu, Qingkun; Smalyukh, Ivan I

2015-08-28

We experimentally realize polydomain and monodomain chiral ferromagnetic liquid crystal colloids that exhibit solitonic and knotted vector field configurations. Formed by dispersions of ferromagnetic nanoplatelets in chiral nematic liquid crystals, these colloidal ferromagnets exhibit spontaneous long-range alignment of magnetic dipole moments of individual platelets, giving rise to a continuum of the magnetization field M(r). Competing effects of surface confinement and chirality prompt spontaneous formation and enable the optical generation of localized twisted solitonic structures with double-twist tubes and torus knots of M(r), which exhibit a strong sensitivity to the direction of weak magnetic fields ∼1  mT. Numerical modeling, implemented through free energy minimization to arrive at a field-dependent three-dimensional M(r), shows a good agreement with experiments and provides insights into the torus knot topology of observed field configurations and the corresponding physical underpinnings.

A better way to teach knot tying: a randomized controlled trial comparing the kinesthetic and traditional methods.

PubMed

Huang, Emily; Chern, Hueylan; O'Sullivan, Patricia; Cook, Brian; McDonald, Erik; Palmer, Barnard; Liu, Terrence; Kim, Edward

2014-10-01

Knot tying is a fundamental and crucial surgical skill. We developed a kinesthetic pedagogical approach that increases precision and economy of motion by explicitly teaching suture-handling maneuvers and studied its effects on novice performance. Seventy-four first-year medical students were randomized to learn knot tying via either the traditional or the novel "kinesthetic" method. After 1 week of independent practice, students were videotaped performing 4 tying tasks. Three raters scored deidentified videos using a validated visual analog scale. The groups were compared using analysis of covariance with practice knots as a covariate and visual analog scale score (range, 0 to 100) as the dependent variable. Partial eta-square was calculated to indicate effect size. Overall rater reliability was .92. The kinesthetic group scored significantly higher than the traditional group for individual tasks and overall, controlling for practice (all P < .004). The kinesthetic overall mean was 64.15 (standard deviation = 16.72) vs traditional 46.31 (standard deviation = 16.20; P < .001; effect size = .28). For novices, emphasizing kinesthetic suture handling substantively improved performance on knot tying. We believe this effect can be extrapolated to more complex surgical skills. Copyright © 2014 Elsevier Inc. All rights reserved.

Characterization of the inner knot of the crab: The site of the gamma-ray flares?

DOE PAGES

Rudy, Alexander; Horns, Dieter; DeLuca, Andrea; ...

2015-09-16

A particularly intriguing recent result from γ-ray astronomy missions is the detection of powerful flares from the Crab Nebula, which challenges the current understanding of pulsar wind nebulae and acceleration mechanisms. In order to search for the production site(s) of these flares, we conducted a multi-wavelength observing campaign using Keck, the Hubble Space Telescope (HST), and the Chandra X-ray Observatory. As the short timescales of the γ-ray flares (more » $$\\lesssim 1$$ day) suggest a small emitting region, the Crab's inner knot (about 0.6 arcsec from the pulsar) is a candidate site for such flaring. Our paper describes observations of the inner knot, seeking to understand its nature and possible relationship with γ-ray flares. Using singular-value decomposition, analysis of the HST images yielded results consistent with traditional methods while substantially reducing some uncertainties. These analyses show that the knot's intrinsic properties (especially size and brightness) are correlated with its (projected) separation from the pulsar. This characterization of the inner knot helps in constraining standard shock model parameters, under the assumption that the knot lies near the shocked surface. While the standard shock model gives good agreement in several respects, two puzzles persist: (a) the observed angular size of the knot relative to the pulsar–knot separation is much smaller than expected; and (b) the variable high degree of polarization (reported by others) is difficult to reconcile with a highly relativistic downstream flow. But, the IR–optical flux of the inner knot is marginally consistent with the shock accelerating most of the Nebula's optical-emitting particles.« less

Predicting internal lumber grade from log surface knots: actual and simulated results.

Treesearch

Christine Todoroki; Robert A. Monserud; Dean L. Parry

2005-01-01

The purpose of this study was threefold: 1) compare actual with simulated lumber yields; 2) examine the effect of measurement errors associated with knot angles and morphology. on lumber grade; and 3) investigate methods for predicting lumber quality within unsawn logs from surface knots. Twenty-eight Douglas-fir (Pseudotsuga menziesii(Mii irb.)...

Cutting the Composite Gordian Knot: Untangling the AGN-Starburst Threads in Single Aperture Spectra

NASA Astrophysics Data System (ADS)

Flury, Sophia; Moran, Edward C.

2018-01-01

Standard emission line diagnostics are able to segregate star-forming galaxies and Seyfert nuclei, and it is often assumed that ambiguous emission-line galaxies falling between these two populations are “composite” objects exhibiting both types of photoionization. We have developed a method that predicts the most probable H II and AGN components that could plausibly explain the “composite” classed objects solely on the basis of their SDSS spectra. The majority of our analysis is driven by empirical relationships revealed by SDSS data rather than theoretical models founded in assumptions. To verify our method, we have compared the predictions of our model with publicly released IFU data from the S7 survey and find that composite objects are not in fact a simple linear combination of the two types of emission. The data reveal a key component in the mixing sequence: geometric dilution of the ionizing radiation which powers the NLR of the active nucleus. When accounting for this effect, our model is successful when applied to several composite-class galaxies. Some objects, however, appear to be at variance with the predicted results, suggesting they may not be powered by black hole accretion.

Development of a sweet cherry pepper line with resistance to the southern root-knot nematode Meloidogyne incognita

USDA-ARS?s Scientific Manuscript database

The southern root-knot nematode (Meloidogyne incognita) is a major pathogen of pepper (Capsicum spp.), causing significant yield losses in heavily infected plants. The N-gene confers resistance to M. incognita, and has been successfully used to mitigate nematode damage in specific pepper varieties f...

Automated knot detection with visual post-processing of Douglas-fir veneer images

Treesearch

C.L. Todoroki; Eini C. Lowell; Dennis Dykstra

2010-01-01

Knots on digital images of 51 full veneer sheets, obtained from nine peeler blocks crosscut from two 35-foot (10.7 m) long logs and one 18-foot (5.5 m) log from a single Douglas-fir tree, were detected using a two-phase algorithm. The algorithm was developed using one image, the Development Sheet, refined on five other images, the Training Sheets, and then applied to...

The mutual attraction of magnetic knots. [solar hydromagnetic instability in sunspot regions

NASA Technical Reports Server (NTRS)

Parker, E. N.

1978-01-01

It is observed that the magnetic knots associated with active regions on the sun have an attraction for each other during the formative period of the active regions, when new magnetic flux is coming to the surface. The attraction disappears when new flux ceases to rise through the surface. Then the magnetic spots and knots tend to come apart, leading to disintegration of the sunspots previously formed. The dissolution of the fields is to be expected, as a consequence of the magnetic repulsion of knots of like polarity and as a consequence of the hydromagnetic exchange instability. The purpose of this paper is to show that the mutual attraction of knots during the formative stages of a sunspot region may be understood as the mutual hydrodynamic attraction of the rising flux tubes. Two rising tubes attract each other, as a consequence of the wake of the leading tube when one is moving behind the other, and as a consequence of the Bernoulli effect when rising side by side.

Rare complication of appendix: small bowel gangrene caused by the appendicular knot.

PubMed

Mohana, R T; Zainal, A A

2017-12-01

Intestinal knot formation was first described by Riverius in 16th century and later by Rokitansky in 1836. We report a very rare cause of small bowel gangrene caused by appendiceal knotting on to the ileum in a previously healthy mid aged lady. Patient underwent laparatomy and right hemicolectomy and primary anastomosis. The intra operative findings were the appendix was twisting (knotting) the small bowel about 40cm from the terminal ileum and causing gangrene to the segment of small bowel. Appendicitis is a common condition and management is usually straightforward. However we must be aware of rare complications which may arise that require a change from the standard treatment of acute appendicitis.

Post-breeding migration and connectivity of red knots in the Western Atlantic

USGS Publications Warehouse

Lyons, James E.; Winn, Bradford; Keyes, Timothy; Kalasz, Kevin S.

2018-01-01

Red knots (Calidris canutus rufa) have 3 distinct nonbreeding regions: 1 in the southeastern United States and Caribbean, another on the northeast coast of Brazil in the Maranhão region, and a third along the Patagonian coasts of Chile and Argentina. Effective conservation and recovery of this threatened long-distance migrant will require knowledge of population structure, migration ecology, and abundance and distribution throughout the annual cycle. We conducted a stopover population and biogeographic assessment of knots at the Altamaha River Delta, Georgia, an important stopover area in the southeastern United States. We estimated stopover population size and stopover duration during post-breeding migration in 2011 at the Altamaha study area using mark-resight data, and we inferred nonbreeding regions for this stopover population using stable isotope ratios of carbon and nitrogen in feathers, and observations (sightings and captures) during boreal winter from across the hemisphere. With an integrated Bayesian analysis of all these data, we also estimated the number of birds in the southeastern United States and northern Brazil during boreal winter. For mark-resight analyses in Georgia, we made observations of marked individuals during 14 weeks from early August to early November 2011 and detected 814 individually marked birds. We used the Jolly-Seber mark-recapture model and estimated the southbound passage population at approximately 23,400 red knots. In ongoing studies elsewhere, isotope samples were collected from 175 (21%) of the 814 birds detected in our study, and ≥1 sighting or capture record during boreal winter was located in data repositories for 659 birds (81%). Isotopic signatures and boreal winter records indicate that the majority (82–96%) of the birds that stopped at the Altamaha Delta spend the boreal winter in the northern part of the nonbreeding range (southeast USA, Caribbean, and northern Brazil). Knots migrating to the southeastern

Development of enzyme linked immunosorbent assay (ELISA) for the detection of root-knot nematode Meloidogyne incognita.

PubMed

Kapur-Ghai, J; Kaur, M; Goel, P

2014-09-01

Root-knot nematodes (Meloidogyne incognita) are obligate, sedentary plant endoparasites that are extremely polyphagous in nature and cause severe economic losses in agriculture. Hence, it is essential to control the parasite at an early stage. For any control strategy to be effective, an early and accurate diagnosis is of paramount importance. Immunoassays have the inherent advantages of sensitivity and specificity; have the potential to identify and quantify these plant-parasitic nematodes. Hence, in the present studies, enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of M.incognita antigens. First an indirect ELISA was developed for detection and titration of anti-M.incognita antibodies. Results indicated as high as 320 K titre of the antisera. Finally competitive inhibition ELISA was developed employing these anti-M.incognita antibodies for detection of M.incognita antigens. Sensitivity of ELISA was 10 fg. Competitive inhibition ELISA developed in the present studies has the potential of being used as an easy, rapid, specific and sensitive diagnostic tool for the detection of M.incognita infection.

Unraveling the Gordian knot: red blood cell storage lesion and transfusion outcomes

PubMed Central

Tzounakas, Vassilis L.; Kriebardis, Anastasios G.; Seghatchian, Jerard; Papassideri, Issidora S.; Antonelou, Marianna H.

2017-01-01

What is following the impressive progress that has been made? During the last couple of years several tremors have shaken the field of Transfusion Medicine. The epicentres of those tremors were located on novel insights into the RBC storage lesion, on emerging connections between storage lesion and post-transfusion performance and effects, and on acknowledging that storage time is only one (rather than the most prominent) of the parameters which contribute to the progression of storage lesion in any given unit of blood. The optimisation of bio-preservation conditions emerged at the same time with all-new scientific knowledge gained by advances in research tools, implementation of technological innovations, and application of elegant in vitro and in vivo models of transfusion. Simultaneously, one after another, all the reported randomised clinical trials concluded, with spectacular consensus, that there is no significant difference in the rate of adverse clinical events (including death) among patients who underwent transfusion with fresh (and presumably good) or standard of care (and presumably bad) blood. The comparative analysis and comprehension of the aforementioned data would set the context for the next generation of research in blood transfusion science, since the need for safer and more efficient transfusions remains. PMID:28263169

Resolving the Gordian Knot: Srs2 Strips Intermediates Formed during Homologous Recombination.

PubMed

Ghodke, Harshad; Lewis, Jacob S; van Oijen, Antoine M

2018-03-01

Cells use a suite of specialized enzymes to repair chromosomal double-strand breaks (DSBs). Two recent studies describe how single-molecule fluorescence imaging techniques are used in the direct visualization of some of the key molecular steps involved. De Tullio et al. and Kaniecki et al. watch individual Srs2 helicase molecules disrupt repair intermediates formed by RPA, Rad51, and Rad52 on DNA during homologous recombination. Copyright © 2017 Elsevier Ltd. All rights reserved.

Expression of almond KNOTTED1 homologue (PdKn1) anticipates adventitious shoot initiation

USDA-ARS?s Scientific Manuscript database

Background and Aims: The transcription factor encoded by the gene Knotted1 is a nuclear homeodomain protein, regulating meristematic cells at the shoot apical meristem. It has been proven that Knotted1 (KN1) has a role in the switch from an indeterminate to determinate cell fate and as such this gen...

Knot positioning during McDonald cervical cerclage, does it make a difference? A cohort study.

PubMed

Atia, Hytham; Ellaithy, Mohamed; Altraigey, Ahmed; Ibrahim, Heba

2018-05-15

To study the effect of McDonald cerclage knot position on the different maternal and neonatal outcomes. This historical cohort study included women with singleton pregnancy who had a prophylactic McDonald cervical cerclage between 1 May 2010 and 31 September 2017. Maternal and neonatal outcome parameters were compared between the anterior and posterior knot cerclage procedures. The primary outcome measure was the rate of term birth. 550 Women had a prophylactic McDonald cervical cerclage, 306 with anterior knot (Group A) and 244 with posterior knot (Group B). There were no statistically significant differences regarding gestational age (GA) at delivery (36.3 ± 4.2 versus 35.8 ± 5.3 for groups A and B respectively), term birth rate, post-cerclage cervical length, symptomatic vaginitis, urinary tract infection, difficult cerclage removal and cervical lacerations. Similarly, there were no statistically significant differences as regards the studied neonatal outcomes including take home babies, neonatal intensive care admission, respiratory distress syndrome and neonatal sepsis. Survival analysis on GA at delivery demonstrated no statistically significant difference as regards the proportion of term deliveries in the anterior and posterior knot cerclage groups (log-rank test p-value = .478). Knot positioning during McDonald cervical cerclage, anteriorly or posteriorly, didn't significantly impact the studied maternal and neonatal outcomes.

Pseudomonas savastanoi pv. savastanoi: some like it knot.

PubMed

Ramos, Cayo; Matas, Isabel M; Bardaji, Leire; Aragón, Isabel M; Murillo, Jesús

2012-12-01

Pseudomonas savastanoi pv. savastanoi is the causal agent of olive (Olea europaea) knot disease and an unorthodox member of the P. syringae complex, causing aerial tumours instead of the foliar necroses and cankers characteristic of most members of this complex. Olive knot is present wherever olive is grown; although losses are difficult to assess, it is assumed that olive knot is one of the most important diseases of the olive crop. The last century witnessed a large number of scientific articles describing the biology, epidemiology and control of this pathogen. However, most P. savastanoi pv. savastanoi strains are highly recalcitrant to genetic manipulation, which has effectively prevented the pathogen from benefitting from the scientific progress in molecular biology that has elevated the foliar pathogens of the P. syringae complex to supermodels. A number of studies in recent years have made significant advances in the biology, ecology and genetics of P. savastanoi pv. savastanoi, paving the way for the molecular dissection of its interaction with other nonpathogenic bacteria and their woody hosts. The selection of a genetically pliable model strain was soon followed by the development of rapid methods for virulence assessment with micropropagated olive plants and the analysis of cellular interactions with the plant host. The generation of a draft genome of strain NCPPB 3335 and the closed sequence of its three native plasmids has allowed for functional and comparative genomic analyses for the identification of its pathogenicity gene complement. This includes 34 putative type III effector genes and genomic regions, shared with other pathogens of woody hosts, which encode metabolic pathways associated with the degradation of lignin-derived compounds. Now, the time is right to explore the molecular basis of the P. savastanoi pv. savastanoi-olive interaction and to obtain insights into why some pathovars like it necrotic and why some like it knot

High-speed knots in the hourglass-shaped planetary nebula Hubble 12

NASA Astrophysics Data System (ADS)

Vaytet, N.; Rushton, A. P.; Lloyd, M.; Lopez, J. A.; Meaburn, J.; O'Brien, T. J.; Mitchell, D. L.; Pollacco, D.

We present a detailed kinematical analysis of the young compact hourglass-shaped planetary nebula Hb 12. We performed optical imaging and longslit spectroscopy of Hb 12 using the Manchester echelle spectrometer with the 2.1-m San Pedro Martir telescope. We reveal, for the first time, the presence of end caps (or knots) aligned with the bipolar lobes of the planetary nebula shell in a deep [N ii] 6584 image of Hb 12. We measured from our spectroscopy radial velocities of about 120 km s-1 for these knots. We have derived the inclination angle of the hourglass shaped nebular shell to be 65° to the line of sight. It has been suggested that Hb 12's central star system is an eclipsing binary which would imply a binary inclination of at least 80°. However, if the central binary has been the major shaping influence on the nebula then both nebula and binary would be expected to share a common inclination angle. Finally, we report the discovery of high-velocity knots with Hubble-type velocities, close to the core of Hb 12, observed in HA and oriented in the same direction as the end caps. Very different velocities and kinematical ages were calculated for the outer and inner knots showing that they may originate from different outburst events.

Ethnomathematics in Arfak (West Papua-Indonesia): Hidden Mathematics on Knot of Rumah Kaki Seribu

ERIC Educational Resources Information Center

Haryanto; Nusantara, Toto; Subanji; Abadyo

2016-01-01

This ethnomathematics article focused on the models of knot which is used in the frame of "Rumah Kaki Seribu." The knot model itself was studied mathematically. The results of this study revealed the way Arfak tribal communities think mathematically. This article uses exploration, documentation, interview, experiments and literature…

BPS counting for knots and combinatorics on words

NASA Astrophysics Data System (ADS)

Kucharski, Piotr; Sułkowski, Piotr

2016-11-01

We discuss relations between quantum BPS invariants defined in terms of a product decomposition of certain series, and difference equations (quantum A-polynomials) that annihilate such series. We construct combinatorial models whose structure is encoded in the form of such difference equations, and whose generating functions (Hilbert-Poincaré series) are solutions to those equations and reproduce generating series that encode BPS invariants. Furthermore, BPS invariants in question are expressed in terms of Lyndon words in an appropriate language, thereby relating counting of BPS states to the branch of mathematics referred to as combinatorics on words. We illustrate these results in the framework of colored extremal knot polynomials: among others we determine dual quantum extremal A-polynomials for various knots, present associated combinatorial models, find corresponding BPS invariants (extremal Labastida-Mariño-Ooguri-Vafa invariants) and discuss their integrality.

Dodging the crisis of folding proteins with knots

NASA Astrophysics Data System (ADS)

Sulkowska, Joanna

2009-03-01

Proteins with nontrivial topology, containing knots and slipknots, have the ability to fold to their native states without any additional external forces invoked. A mechanism is suggested for folding of these proteins, such as YibK and YbeA, which involves an intermediate configuration with a slipknot. It elucidates the role of topological barriers and backtracking during the folding event. It also illustrates that native contacts are sufficient to guarantee folding in around 1-2% of the simulations, and how slipknot intermediates are needed to reduce the topological bottlenecks. As expected, simulations of proteins with similar structure but with knot removed fold much more efficiently, clearly demonstrating the origin of these topological barriers. Although these studies are based on a simple coarse-grained model, they are already able to extract some of the underlying principles governing folding in such complex topologies.

Untying a nanoscale knotted polymer structure to linear chains for efficient gene delivery in vitro and to the brain

NASA Astrophysics Data System (ADS)

Newland, B.; Aied, A.; Pinoncely, A. V.; Zheng, Y.; Zhao, T.; Zhang, H.; Niemeier, R.; Dowd, E.; Pandit, A.; Wang, W.

2014-06-01

The purpose of this study was to develop a platform transfection technology, for applications in the brain, which could transfect astrocytes without requiring cell specific functionalization and without the common cause of toxicity through high charge density. Here we show that a simple and scalable preparation technique can be used to produce a ``knot'' structured cationic polymer, where single growing chains can crosslink together via disulphide intramolecular crosslinks (internal cyclizations). This well-defined knot structure can thus ``untie'' under reducing conditions, showing a more favorable transfection profile for astrocytes compared to 25 kDa-PEI (48-fold), SuperFect® (39-fold) and Lipofectamine®2000 (18-fold) whilst maintaining neural cell viability at over 80% after four days of culture. The high transfection/lack of toxicity of this knot structured polymer in vitro, combined with its ability to mediate luciferase transgene expression in the adult rat brain, demonstrates its use as a platform transfection technology which should be investigated further for neurodegenerative disease therapies.The purpose of this study was to develop a platform transfection technology, for applications in the brain, which could transfect astrocytes without requiring cell specific functionalization and without the common cause of toxicity through high charge density. Here we show that a simple and scalable preparation technique can be used to produce a ``knot'' structured cationic polymer, where single growing chains can crosslink together via disulphide intramolecular crosslinks (internal cyclizations). This well-defined knot structure can thus ``untie'' under reducing conditions, showing a more favorable transfection profile for astrocytes compared to 25 kDa-PEI (48-fold), SuperFect® (39-fold) and Lipofectamine®2000 (18-fold) whilst maintaining neural cell viability at over 80% after four days of culture. The high transfection/lack of toxicity of this knot

Diagnosing and attributing neuropsychiatric events to systemic lupus erythematosus: time to untie the Gordian knot?

PubMed

Tay, Sen Hee; Mak, Anselm

2017-04-01

Neurological and psychiatric syndromes, collectively referred to as NPSLE, occur frequently in SLE. The frequency of NPSLE varies from 21 to 95%; however, only 13-38% of neuropsychiatric (NP) events could be attributable to SLE in the NPSLE SLICC inception cohort. This variability in the frequency of NPSLE is attributable to the low specificity of the ACR case definitions for SLE-attributed NP syndromes, inclusion of minor NP events in the ACR nomenclature, difficulty in ascertainment of NP events and diverse experience of rheumatologists in the clinical assessment of NP events. Making the correct and early attribution of NP events to SLE is important to institute appropriate immunosuppressive treatment for favourable outcomes. Various attribution models using composite decision rules have been developed and used to ascribe NP events to SLE. This review will focus on the various clinical presentations, diagnostic work-up and attributions of the common NPSLE syndromes, including other NP events not included in the ACR nomenclature but which have come to attention in recent years. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Demographic consequences of migratory stopover: linking red knot survival to horseshoe crab spawning abundance

USGS Publications Warehouse

McGowan, Conor P.; Hines, James E.; Nichols, James D.; Lyons, James E.; Smith, David; Kalasz, Kevin S.; Niles, Lawrence J.; Dey, Amanda D.; Clark, Nigel A.; Atkinson, Philip W.; Minton, Clive D.T.; Kendall, William

2011-01-01

Understanding how events during one period of the annual cycle carry over to affect survival and other fitness components in other periods is essential to understanding migratory bird demography and conservation needs. Previous research has suggested that western Atlantic red knot (Calidris canutus rufa) populations are greatly affected by horseshoe crab (Limulus polyphemus) egg availability at Delaware Bay stopover sites during their spring northward migration. We present a mass-based multistate, capturerecapture/resighting model linking (1) red knot stopover mass gain to horseshoe crab spawning abundance and (2) subsequent apparent annual survival to mass state at the time of departure from the Delaware Bay stopover area. The model and analysis use capture-recapture/resighting data with over 16,000 individual captures and 13,000 resightings collected in Delaware Bay over a 12 year period from 1997–2008, and the results are used to evaluate the central management hypothesis that red knot populations can be influenced by horseshoe crab harvest regulations as part of a larger adaptive management effort. Model selection statistics showed support for a positive relationship between horseshoe crab spawning abundance during the stopover and the probability of red knots gaining mass (parameter coefficient from the top model b = 1.71, SE = 0.46). Our analyses also supported the link between red knot mass and apparent annual survival, although average estimates for the two mass classes differed only slightly. The addition of arctic snow depth as a covariate influencing apparent survival improved the fit of the data to the models (parameter coefficient from the top model b = 0.50, SE = 0.08). Our results indicate that managing horseshoe crab resources in the Delaware Bay has the potential to improve red knot population status.

Multispecies modeling for adaptive management of horseshoe crabs and red knots in the Delaware Bay

USGS Publications Warehouse

McGowan, Conor P.; Smith, David; Sweka, John A.; Martin, Julien; Nichols, James D.; Wong, Richard; Lyons, James E.; Niles, Lawrence J.; Kalasz, Kevin; Brust, Jeffrey; Klopfer, Michelle; Spear, Braddock

2011-01-01

Adaptive management requires that predictive models be explicit and transparent to improve decisions by comparing management actions, directing further research and monitoring, and facilitating learning. The rufa subspecies of red knots (Calidris canutus rufa), which has recently exhibited steep population declines, relies on horseshoe crab (Limulus polyphemus) eggs as their primary food source during stopover in Delaware Bay during spring migration. We present a model with two different parameterizations for use in the adaptive management of horseshoe crab harvests in the Delaware Bay that links red knot mass gain, annual survival, and fecundity to horseshoe crab dynamics. The models reflect prevailing hypotheses regarding ecological links between these two species. When reported crab harvest from 1998 to 2008 was applied, projections corresponded to the observed red knot population abundances depending on strengths of the demographic relationship between these species. We compared different simulated horseshoe crab harvest strategies to evaluate whether, given this model, horseshoe crab harvest management can affect red knot conservation and found that restricting harvest can benefit red knot populations. Our model is the first to explicitly and quantitatively link these two species and will be used within an adaptive management framework to manage the Delaware Bay system and learn more about the specific nature of the linkage between the two species.

Synthesis of Ga 2O 3 chains with closely spaced knots connected by nanowires

NASA Astrophysics Data System (ADS)

Dai, L.; You, L. P.; Duan, X. F.; Lian, W. C.; Qin, G. G.

2004-07-01

Chains of closely spaced metal or semiconductor particles have potential applications in optoelectronics and single electron devices. We report, for the first time, the synthesis of Ga 2O 3 chains with closely spaced knots connected by nanowires using the thermal evaporation method with a specially designed quartz boat. The Ga 2O 3 chains grew only on the Si substrates where Au catalyst or Ga droplets were coated. The average diameter of the knots is about 450 nm and that of the nanowires is about 50 nm. The selected area electron diffraction of either a knot or a connecting nanowire includes two sets of overlapped single crystal electron diffraction patterns which belong to the [1 0 2] and [1 0 1¯] crystal zone axes of the monoclinic β-Ga 2O 3 phase, respectively. The knot and its neighbor nanowire have the common ( 2¯ 0 1) growth planes at their interface. A mechanism model for the Ga 2O 3 chains synthesis based on the vapor-liquid-solid mechanism is discussed.

16D10 siRNAs inhibit root-knot nematode infection in transgenic grape hairy roots

USDA-ARS?s Scientific Manuscript database

To develop a biotech-based solution for controlling Root-knot nematodes (RKNs) in grapes, we evaluated the efficacy of plant-derived RNA interference (RNAi) silencing of a conserved RKN effector gene, 16D10, for nematode resistance in transgenic grape hairy roots. Two hairpin-based silencing constru...

Comparison of volume, security, and biomechanical strength of square and Aberdeen termination knots tied with 4-0 polyglyconate and used for termination of intradermal closures in canine cadavers.

PubMed

Regier, Penny J; Smeak, Daniel D; Coleman, Kristin; McGilvray, Kirk C

2015-08-01

To compare volumes of square knots and Aberdeen knots in vitro and evaluate security of these knot types when used as buried terminal knots for continuous intradermal wound closures in canine cadavers. Experimental study. 24 surgically closed, full-thickness, 4-cm, epidermal wounds in 4 canine cadavers and 80 knots tied in vitro. Continuous intradermal closures were performed with 4-0 polyglyconate and completed with a buried knot technique. Surgeon (intern or experienced surgeon) and termination knot type (4-throw square knot or 2 + 1 Aberdeen knot; 12 each) were randomly assigned. Closed wounds were excised, and a servohydraulic machine applied tensile load perpendicular to the long axis of the suture line. A load-displacement curve was generated for each sample; maximum load, displacement, stiffness, and mode of construct failure were recorded. Volumes of 2 + 1 Aberdeen (n = 40) and 4-throw square knots (40) tied on a suture board were measured on the basis of a cylindrical model. Aberdeen knots had a mean smaller volume (0.00045 mm(3)) than did square knots (0.003838 mm(3)). Maximum load and displacement did not differ between construct types. Mean stiffness of Aberdeen knot constructs was greater than that of square knots. The 2 + 1 Aberdeen knot had a smaller volume than the 4-throw square knot and was as secure. Although both knots may be reliably used in a clinical setting as the termination knot at the end of a continuous intradermal line, the authors advocate use of the Aberdeen terminal knot on the basis of ease of burying the smaller knot.

Knot probability of polygons subjected to a force: a Monte Carlo study

NASA Astrophysics Data System (ADS)

Janse van Rensburg, E. J.; Orlandini, E.; Tesi, M. C.; Whittington, S. G.

2008-01-01

We use Monte Carlo methods to study the knot probability of lattice polygons on the cubic lattice in the presence of an external force f. The force is coupled to the span of the polygons along a lattice direction, say the z-direction. If the force is negative polygons are squeezed (the compressive regime), while positive forces tend to stretch the polygons along the z-direction (the tensile regime). For sufficiently large positive forces we verify that the Pincus scaling law in the force-extension curve holds. At a fixed number of edges n the knot probability is a decreasing function of the force. For a fixed force the knot probability approaches unity as 1 - exp(-α0(f)n + o(n)), where α0(f) is positive and a decreasing function of f. We also examine the average of the absolute value of the writhe and we verify the square root growth law (known for f = 0) for all values of f.

Avian influenza virus antibodies in Pacific Coast Red Knots (Calidris canutus rufa)

USGS Publications Warehouse

Johnson, James A.; DeCicco, Lucas H.; Ruthrauff, Daniel R.; Krauss, Scott; Hall, Jeffrey S.

2014-01-01

Prevalence of avian influenza virus (AIV) antibodies in the western Atlantic subspecies of Red Knot (Calidris canutus rufa) is among the highest for any shorebird. To assess whether the frequency of detection of AIV antibodies is high for the species in general or restricted only to C. c. rufa, we sampled the northeastern Pacific Coast subspecies of Red Knot (Calidris canutus roselaari) breeding in northwestern Alaska. Antibodies were detected in 90% of adults and none of the chicks sampled. Viral shedding was not detected in adults or chicks. These results suggest a predisposition of Red Knots to AIV infection. High antibody titers to subtypes H3 and H4 were detected, whereas low to intermediate antibody levels were found for subtypes H10 and H11. These four subtypes have previously been detected in shorebirds at Delaware Bay (at the border of New Jersey and Delaware) and in waterfowl along the Pacific Coast of North America.

Are Khovanov-Rozansky polynomials consistent with evolution in the space of knots?

NASA Astrophysics Data System (ADS)

Anokhina, A.; Morozov, A.

2018-04-01

R-coloured knot polynomials for m-strand torus knots Torus [ m, n] are described by the Rosso-Jones formula, which is an example of evolution in n with Lyapunov exponents, labelled by Young diagrams from R ⊗ m . This means that they satisfy a finite-difference equation (recursion) of finite degree. For the gauge group SL( N ) only diagrams with no more than N lines can contribute and the recursion degree is reduced. We claim that these properties (evolution/recursion and reduction) persist for Khovanov-Rozansky (KR) polynomials, obtained by additional factorization modulo 1 + t, which is not yet adequately described in quantum field theory. Also preserved is some weakened version of differential expansion, which is responsible at least for a simple relation between reduced and unreduced Khovanov polynomials. However, in the KR case evolution is incompatible with the mirror symmetry under the change n -→ - n, what can signal about an ambiguity in the KR factorization even for torus knots.

Characterization of the Inner Knot of the Crab: the Site of the Gamma-ray Flares?

NASA Technical Reports Server (NTRS)

Weisskopf, Martin C.

2015-01-01

One of the most intriguing recent discoveries has been the detection of powerful gamma-ray flares from the Crab Nebula. Such events, with a recurrence time of about once per year, can be so dramatic to make the system the brightest source in the gamma-ray sky as occurred, e.g. in April 2011. These flares challenge our understanding of how pulsar wind nebulae work and defy current astrophysical models for particle acceleration. We present here our study of the inner knot located within a fraction of an arcsecond from the pulsar with the aim of characterizing the feature and asking if this might be the site of the origin of the gamma-ray flares. We took data using Keck, HST, and Chandra obtained as part of our multi-wavelength campaign to identify the source of the enigmatic flares. We set an upper limit as to the gamma-ray flux from the knot. We also find that the dimensions, surface brightness, flux, etc. of the optical and infrared knot are all correlated with distance from the pulsar. This distance, in turn, varies with time. In addition to this most thorough characterization of the inner knot's properties, we examine the hypothesis that the knot may be the site of the flares by examining the knot separation versus the Fermi/LAT gamma-ray flux. Finally, as part of this research, we make use of a new approach employing singular value decomposition (SVD) for analyzing time series of images and compare the approach to more traditional methods. Our conclusions are only refined but not impacted by using the new approach.

The Role of Non-Native Interactions in the Folding of Knotted Proteins: Insights from Molecular Dynamics Simulations

PubMed Central

Covino, Roberto; Škrbić, Tatjana; Beccara, Silvio a; Faccioli, Pietro; Micheletti, Cristian

2014-01-01

For several decades, the presence of knots in naturally-occurring proteins was largely ruled out a priori for its supposed incompatibility with the efficiency and robustness of folding processes. For this very same reason, the later discovery of several unrelated families of knotted proteins motivated researchers to look into the physico-chemical mechanisms governing the concerted sequence of folding steps leading to the consistent formation of the same knot type in the same protein location. Besides experiments, computational studies are providing considerable insight into these mechanisms. Here, we revisit a number of such recent investigations within a common conceptual and methodological framework. By considering studies employing protein models with different structural resolution (coarse-grained or atomistic) and various force fields (from pure native-centric to realistic atomistic ones), we focus on the role of native and non-native interactions. For various unrelated instances of knotted proteins, non-native interactions are shown to be very important for favoring the emergence of conformations primed for successful self-knotting events. PMID:24970203

Use of gadolinium chloride as a contrast agent for imaging spruce knots by magnetic resonance

Treesearch

Thomas L. Eberhardt; Chi-Leung So; Amy H. Herlihy; Po-Wah So

2006-01-01

Treatments of knot-containing spruce wood blocks with a paramagnetic salt, gadolinium (III) chloride, in combination with solvent pretreatments, were evaluated as strategies to enhance the visualization of wood features by magnetic resonance imaging (MRI). Initial experiments with clear wood and excised knot samples showed differences in moisture uptake after...

Automated image analysis of placental villi and syncytial knots in histological sections.

PubMed

Kidron, Debora; Vainer, Ifat; Fisher, Yael; Sharony, Reuven

2017-05-01

Delayed villous maturation and accelerated villous maturation diagnosed in histologic sections are morphologic manifestations of pathophysiological conditions. The inter-observer agreement among pathologists in assessing these conditions is moderate at best. We investigated whether automated image analysis of placental villi and syncytial knots could improve standardization in diagnosing these conditions. Placentas of antepartum fetal death at or near term were diagnosed as normal, delayed or accelerated villous maturation. Histologic sections of 5 cases per group were photographed at ×10 magnification. Automated image analysis of villi and syncytial knots was performed, using ImageJ public domain software. Analysis of hundreds of histologic images was carried out within minutes on a personal computer, using macro commands. Compared to normal placentas, villi from delayed maturation were larger and fewer, with fewer and smaller syncytial knots. Villi from accelerated maturation were smaller. The data were further analyzed according to horizontal placental zones and groups of villous size. Normal placentas can be discriminated from placentas of delayed or accelerated villous maturation using automated image analysis. Automated image analysis of villi and syncytial knots is not equivalent to interpretation by the human eye. Each method has advantages and disadvantages in assessing the 2-dimensional histologic sections representing the complex, 3-dimensional villous tree. Image analysis of placentas provides quantitative data that might help in standardizing and grading of placentas for diagnostic and research purposes. Copyright © 2017 Elsevier Ltd. All rights reserved.

New knotted solutions of Maxwell's equations

NASA Astrophysics Data System (ADS)

Hoyos, Carlos; Sircar, Nilanjan; Sonnenschein, Jacob

2015-06-01

In this paper we have further developed the study of topologically non-trivial solutions of vacuum electrodynamics. We have discovered a novel method of generating such solutions by applying conformal transformations with complex parameters on known solutions expressed in terms of Bateman's variables. This has enabled us to obtain a wide class of solutions from the basic configuration, such as constant electromagnetic fields and plane-waves. We have introduced a covariant formulation of Bateman's construction and discussed the conserved charges associated with the conformal group as well as a set of four types of conserved helicities. We have also given a formulation in terms of quaternions. This led to a simple map between the electromagnetic knotted and linked solutions into flat connections of SU(2) gauge theory. We have computed the corresponding Chern-Simons charge in a class of solutions and the charge takes integer values.

[Controlling effect of antagonist bioorganic fertilizer on tomato root-knot nematode].

PubMed

Zhu, Zhen; Chen, Fang; Xiao, Tong-jian; Wang, Xiao-hui; Ran, Wei; Yang, Xing-ming; Shen, Qi-rong

2011-04-01

Indoor in vitro culture experiment and greenhouse pot experiment were conducted to evaluate the capabilities of three bacterial strains XZ-173 (Bacillus amyloliquefaciens), SL-25 (B. gibsonii), and KS-62 (Paenibacillus polymyxa) that can hydrolyze collagen protein in controlling tomato root-knot nematode. In the in vitro culture experiment, suspensions of XZ-173, SL-25, and KS-62 induced a mortality rate of 75.9%, 66.7%, and 50.0% to the second-stage junior nematode within 24 h, and decreased the egg hatching rate to 17.8%, 28.9% and 37.6% after 7-day incubation, respectively, in contrast to the 17.4% mortality rate and 53.6% egg hatching rate in the control (sterilized water). In the greenhouse pot experiment, the bioorganic fertilizer mixed with equal parts of fermented XZ-173, SL-25, and KS-62 gained the best result, with the root-knot nematode population in rhizosphere soil decreased by 84.0% as compared with the control. The bioorganic fertilizer also decreased the numbers of galls and eggs on tomato roots significantly, and increased the underground and aboveground biomass of tomato. Therefore, antagonist bioorganic fertilizer has promising potential in controlling root-knot nematode.

Untying the Gordian knot: policies, practices, and ethical issues related to banking of umbilical cord blood

PubMed Central

Kurtzberg, Joanne; Lyerly, Anne Drapkin; Sugarman, Jeremy

2005-01-01

Since the first successful transplantation of umbilical cord blood in 1988, cord blood has become an important source of hematopoietic stem and progenitor cells for the treatment of blood and genetic disorders. Significant progress has been accompanied by challenges for scientists, ethicists, and health policy makers. With the recent recognition of the need for a national system for the collection, banking, distribution, and use of cord blood and the increasing focus on cord blood as an alternative to embryos as a source of tissue for regenerative medicine, cord blood has garnered significant attention. We review the development of cord blood banking and transplantation and then discuss the scientific and ethical issues influencing both established and investigational practices surrounding cord blood collection, banking, and use. PMID:16200191

Comparison of ultrasonic suture welding and traditional knot tying in a rabbit rotator cuff repair model.

PubMed

Nho, Shane J; Cole, Brian J; Mazzocca, Augustus D; Williams, James M; Romeo, Anthony A; Bush-Joseph, Charles A; Bach, Bernard R; Hallab, Nadim J

2006-01-01

The purpose of this study is to evaluate ultrasonic suture welding of monofilament suture in an animal model of rotator cuff repair with biomechanical and histologic analyses. We randomly assigned 46 shoulders in 23 rabbits to 1 of 3 treatment groups: sham-operated (n = 15), knotted (n = 15), and welded (n = 16). Supraspinatus defects were surgically created and acutely repaired with suture anchors loaded with either No. 2-0 Ethibond for knotted group or No. 2-0 nylon for welded shoulders. Eighteen weeks postoperatively, all animals were killed, and the shoulders underwent either biomechanical testing or histologic analysis. The maximum stress of the sham-operated group (20.6 N/mm2) was significantly greater than that of both the knotted (10.2 N/mm2) and welded (8.3 N/mm2) groups (P < .05), but no differences were observed between the knotted and welded groups. Although some histologic changes were noted, none was considered to be significant to distinguish either group.

A summary of modulus of elasticity and knot size surveys for laminating grades of lumber

Treesearch

R. W. Wolfe; R. C. Moody

1981-01-01

A summary of modulus of elasticity (MOE) and knot data is presented for grades of lumber commonly used to manufacture glued-laminated (glulam) timber by the laminating Industry. Tabulated values represent 30 different studies covering a time span of over 16 years. Statistical estimates of average and near-maximum knot sizes as well as mean and coefficient of variation...

The Gordian Knot: Analysis of United States Support to Ethnic-Based Resistance Movements

DTIC Science & Technology

2002-04-09

The Protestant Moravian Church is the next largest category and is the primary religion of the Indians, Creole, and the remaining Whites. Again, the...included changes in education and medical services.54 Before the Nicaraguan revolution, Moravian Church organizations provided most of these services...introduced Spanish speaking Cuban teachers.m Moreover, Moravian Church clinics were closed and mostly not replaced with central government resources

Energy and helicity of magnetic torus knots and braids

NASA Astrophysics Data System (ADS)

Oberti, Chiara; Ricca, Renzo L.

2018-02-01

By considering steady magnetic fields in the shape of torus knots and unknots in ideal magnetohydrodynamics, we compute some fundamental geometric and physical properties to provide estimates for magnetic energy and helicity. By making use of an appropriate parametrization, we show that knots with dominant toroidal coils that are a good model for solar coronal loops have negligible total torsion contribution to magnetic helicity while writhing number provides a good proxy. Hence, by the algebraic definition of writhe based on crossing numbers, we show that the estimated values of writhe based on image analysis provide reliable information for the exact values of helicity. We also show that magnetic energy is linearly related to helicity, and the effect of the confinement of magnetic field can be expressed in terms of geometric information. These results can find useful application in solar and plasma physics, where braided structures are often present.

Toward {U}(N|M) knot invariant from ABJM theory

NASA Astrophysics Data System (ADS)

Eynard, Bertrand; Kimura, Taro

2017-06-01

We study {U}(N|M) character expectation value with the supermatrix Chern-Simons theory, known as the ABJM matrix model, with emphasis on its connection to the knot invariant. This average just gives the half-BPS circular Wilson loop expectation value in ABJM theory, which shall correspond to the unknot invariant. We derive the determinantal formula, which gives {U}(N|M) character expectation values in terms of {U}(1|1) averages for a particular type of character representations. This means that the {U}(1|1) character expectation value is a building block for the {U}(N|M) averages and also, by an appropriate limit, for the {U}(N) invariants. In addition to the original model, we introduce another supermatrix model obtained through the symplectic transform, which is motivated by the torus knot Chern-Simons matrix model. We obtain the Rosso-Jones-type formula and the spectral curve for this case.

Finite-size and asymptotic behaviors of the gyration radius of knotted cylindrical self-avoiding polygons.

PubMed

Shimamura, Miyuki K; Deguchi, Tetsuo

2002-05-01

Several nontrivial properties are shown for the mean-square radius of gyration R2(K) of ring polymers with a fixed knot type K. Through computer simulation, we discuss both finite size and asymptotic behaviors of the gyration radius under the topological constraint for self-avoiding polygons consisting of N cylindrical segments with radius r. We find that the average size of ring polymers with the knot K can be much larger than that of no topological constraint. The effective expansion due to the topological constraint depends strongly on the parameter r that is related to the excluded volume. The topological expansion is particularly significant for the small r case, where the simulation result is associated with that of random polygons with the knot K.

Developing objectives with multiple stakeholders: adaptive management of horseshoe crabs and Red Knots in the Delaware Bay

USGS Publications Warehouse

McGowan, Conor P.; Lyons, James E.; Smith, David

2015-01-01

Structured decision making (SDM) is an increasingly utilized approach and set of tools for addressing complex decisions in environmental management. SDM is a value-focused thinking approach that places paramount importance on first establishing clear management objectives that reflect core values of stakeholders. To be useful for management, objectives must be transparently stated in unambiguous and measurable terms. We used these concepts to develop consensus objectives for the multiple stakeholders of horseshoe crab harvest in Delaware Bay. Participating stakeholders first agreed on a qualitative statement of fundamental objectives, and then worked to convert those objectives to specific and measurable quantities, so that management decisions could be assessed. We used a constraint-based approach where the conservation objectives for Red Knots, a species of migratory shorebird that relies on horseshoe crab eggs as a food resource during migration, constrained the utility of crab harvest. Developing utility functions to effectively reflect the management objectives allowed us to incorporate stakeholder risk aversion even though different stakeholder groups were averse to different or competing risks. While measurable objectives and quantitative utility functions seem scientific, developing these objectives was fundamentally driven by the values of the participating stakeholders.

Developing Objectives with Multiple Stakeholders: Adaptive Management of Horseshoe Crabs and Red Knots in the Delaware Bay

NASA Astrophysics Data System (ADS)

McGowan, Conor P.; Lyons, James E.; Smith, David R.

2015-04-01

Structured decision making (SDM) is an increasingly utilized approach and set of tools for addressing complex decisions in environmental management. SDM is a value-focused thinking approach that places paramount importance on first establishing clear management objectives that reflect core values of stakeholders. To be useful for management, objectives must be transparently stated in unambiguous and measurable terms. We used these concepts to develop consensus objectives for the multiple stakeholders of horseshoe crab harvest in Delaware Bay. Participating stakeholders first agreed on a qualitative statement of fundamental objectives, and then worked to convert those objectives to specific and measurable quantities, so that management decisions could be assessed. We used a constraint-based approach where the conservation objectives for Red Knots, a species of migratory shorebird that relies on horseshoe crab eggs as a food resource during migration, constrained the utility of crab harvest. Developing utility functions to effectively reflect the management objectives allowed us to incorporate stakeholder risk aversion even though different stakeholder groups were averse to different or competing risks. While measurable objectives and quantitative utility functions seem scientific, developing these objectives was fundamentally driven by the values of the participating stakeholders.

Potential of tissue culture for breeding root-knot nematode resistance into vegetables.

PubMed

Fassuliotis, G; Bhatt, D P

1982-01-01

Plant protoplast technology is being investigated as a means of transferring root-knot nematode resistance factors from Solanum sisymbriifolium into the susceptible S. melongena. Solanum sisymbriifolium plants regenerated from callus lost resistance to Meloidogyne javanica but retained resistance to M. incognita. Tomato plants cloned from leaf discs of the root-knot nematode resistant 'Patriot' were completely susceptible to M. incognita, while sections of stems and leaves rooted in sand in the absence of growth hormones retained resistance. Changes in resistance persisted for three generations. It is postulated that the exogenous hormonal constituents of the culture medium are modifying the expression of genetic resistance.

Sclera-directed knot technique for securing an encircling band in retinal surgery.

PubMed

Bartov, E; Ginsburg, L H; Ashkenazi, I; Treister, G

1991-10-01

The protruding ends of sutures used to secure the ends of the silicone rubber band placed during many retinal surgical procedures may cause postsurgical irritation, since with presently used suturing techniques, the knot of the suture remains on top of the band, facing the conjunctiva. We describe a suturing technique which, by inverting the band when suturing its ends and then allowing the band to return to its original position, places the knot on the undersurface of the band, against the sclera. Thus, no protruding suture ends are left facing the conjunctiva and the irritation resulting from such a protrusion is averted.

SNP markers tightly linked to root knot nematode resistance in grapevine (Vitis cinerea) identified by a genotyping-by-sequencing approach followed by Sequenom MassARRAY validation

PubMed Central

Morales, Norma B.; Moskwa, Sam; Clingeleffer, Peter R.; Thomas, Mark R.

2018-01-01

Plant parasitic nematodes, including root knot nematode Meloidogyne species, cause extensive damage to agriculture and horticultural crops. As Vitis vinifera cultivars are susceptible to root knot nematode parasitism, rootstocks resistant to these soil pests provide a sustainable approach to maintain grapevine production. Currently, most of the commercially available root knot nematode resistant rootstocks are highly vigorous and take up excess potassium, which reduces wine quality. As a result, there is a pressing need to breed new root knot nematode resistant rootstocks, which have no impact on wine quality. To develop molecular markers that predict root knot nematode resistance for marker assisted breeding, a genetic approach was employed to identify a root knot nematode resistance locus in grapevine. To this end, a Meloidogyne javanica resistant Vitis cinerea accession was crossed to a susceptible Vitis vinifera cultivar Riesling and results from screening the F1 individuals support a model that root knot nematode resistance, is conferred by a single dominant allele, referred as MELOIDOGYNE JAVANICA RESISTANCE1 (MJR1). Further, MJR1 resistance appears to be mediated by a hypersensitive response that occurs in the root apical meristem. Single nucleotide polymorphisms (SNPs) were identified using genotyping-by-sequencing and results from association and genetic mapping identified the MJR1 locus, which is located on chromosome 18 in the Vitis cinerea accession. Validation of the SNPs linked to the MJR1 locus using a Sequenom MassARRAY platform found that only 50% could be validated. The validated SNPs that flank and co-segregate with the MJR1 locus can be used for marker-assisted selection for Meloidogyne javanica resistance in grapevine. PMID:29462210

SNP markers tightly linked to root knot nematode resistance in grapevine (Vitis cinerea) identified by a genotyping-by-sequencing approach followed by Sequenom MassARRAY validation.

PubMed

Smith, Harley M; Smith, Brady P; Morales, Norma B; Moskwa, Sam; Clingeleffer, Peter R; Thomas, Mark R

2018-01-01

Plant parasitic nematodes, including root knot nematode Meloidogyne species, cause extensive damage to agriculture and horticultural crops. As Vitis vinifera cultivars are susceptible to root knot nematode parasitism, rootstocks resistant to these soil pests provide a sustainable approach to maintain grapevine production. Currently, most of the commercially available root knot nematode resistant rootstocks are highly vigorous and take up excess potassium, which reduces wine quality. As a result, there is a pressing need to breed new root knot nematode resistant rootstocks, which have no impact on wine quality. To develop molecular markers that predict root knot nematode resistance for marker assisted breeding, a genetic approach was employed to identify a root knot nematode resistance locus in grapevine. To this end, a Meloidogyne javanica resistant Vitis cinerea accession was crossed to a susceptible Vitis vinifera cultivar Riesling and results from screening the F1 individuals support a model that root knot nematode resistance, is conferred by a single dominant allele, referred as MELOIDOGYNE JAVANICA RESISTANCE1 (MJR1). Further, MJR1 resistance appears to be mediated by a hypersensitive response that occurs in the root apical meristem. Single nucleotide polymorphisms (SNPs) were identified using genotyping-by-sequencing and results from association and genetic mapping identified the MJR1 locus, which is located on chromosome 18 in the Vitis cinerea accession. Validation of the SNPs linked to the MJR1 locus using a Sequenom MassARRAY platform found that only 50% could be validated. The validated SNPs that flank and co-segregate with the MJR1 locus can be used for marker-assisted selection for Meloidogyne javanica resistance in grapevine.

Particle on a torus knot: Constrained dynamics and semi-classical quantization in a magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, Praloy, E-mail: praloydasdurgapur@gmail.com; Pramanik, Souvik, E-mail: souvick.in@gmail.com; Ghosh, Subir, E-mail: subirghosh20@gmail.com

2016-11-15

Kinematics and dynamics of a particle moving on a torus knot poses an interesting problem as a constrained system. In the first part of the paper we have derived the modified symplectic structure or Dirac brackets of the above model in Dirac’s Hamiltonian framework, both in toroidal and Cartesian coordinate systems. This algebra has been used to study the dynamics, in particular small fluctuations in motion around a specific torus. The spatial symmetries of the system have also been studied. In the second part of the paper we have considered the quantum theory of a charge moving in a torusmore » knot in the presence of a uniform magnetic field along the axis of the torus in a semiclassical quantization framework. We exploit the Einstein–Brillouin–Keller (EBK) scheme of quantization that is appropriate for multidimensional systems. Embedding of the knot on a specific torus is inherently two dimensional that gives rise to two quantization conditions. This shows that although the system, after imposing the knot condition reduces to a one dimensional system, even then it has manifested non-planar features which shows up again in the study of fractional angular momentum. Finally we compare the results obtained from EBK (multi-dimensional) and Bohr–Sommerfeld (single dimensional) schemes. The energy levels and fractional spin depend on the torus knot parameters that specifies its non-planar features. Interestingly, we show that there can be non-planar corrections to the planar anyon-like fractional spin.« less

Exploitation of intertidal feeding resources by the red knot Calidris canutus under megatidal conditions (Bay of Saint-Brieuc, France)

NASA Astrophysics Data System (ADS)

Sturbois, Anthony; Ponsero, Alain; Desroy, Nicolas; Le Mao, Patrick; Fournier, Jérôme

2015-02-01

The feeding ecology of the red knot has been widely studied across its wintering range. Red knots mainly select bivalves and gastropods, with differences between sites due to variation in prey availability. The shorebird's diet is also influenced or controlled by the tidal regime. The aim of this paper is to demonstrate the adaptation of foraging red knots to the megatidal environment. The variation in their diet during tidal cycles was studied in the bay of Saint-Brieuc, a functional unit for this species. The method used combined macrofauna, distribution of foraging birds and diet data. Comparative spatial analyses of macrofauna and distribution of foraging red knots have shown that the bay's four benthic assemblages are exploited by birds. By analysing droppings, we highlighted that bivalve molluscs are the main component of their diet, as shown in most overwintering sites. Fifteen types of prey were identified and Donax vittatus was discovered to be a significant prey item. The relative proportion of each main prey item differs significantly depending on the benthic assemblage used to forage. All available benthic assemblages and all potential feeding resources can be used during a single tidal cycle, reflecting an adaptation to megatidal conditions. This approach develops accurate knowledge about the feeding ecology of birds which managers need in order to identify optimal areas for the conservation of waders based on the areas and resources actually used by the birds.

Quiet eye training improves surgical knot tying more than traditional technical training: a randomized controlled study.

PubMed

Causer, Joe; Harvey, Adrian; Snelgrove, Ryan; Arsenault, Gina; Vickers, Joan N

2014-08-01

We examined the effectiveness of technical training (TT) and quiet eye training (QE) on the performance of one-handed square knot tying in surgical residents. Twenty surgical residents were randomly assigned to the 2 groups and completed pretest, training, retention, and transfer tests. Participants wore a mobile eye tracker that simultaneously recorded their gaze and hand movements. Dependent variables were knot tying performance (%), QE duration (%), number of fixations, total movement time (s), and hand movement phase time (s). The QE training group had significantly higher performance scores, a longer QE duration, fewer fixations, faster total knot tying times, and faster movement phase times compared with the TT group. The QE group maintained performance in the transfer test, whereas the TT group significantly decreased performance from retention to transfer. QE training significantly improved learning, retention, and transfer of surgical knot tying compared with a traditional technical approach. Both performance effectiveness (performance outcome) and movement efficiency (hand movement times) were improved using QE modeling, instruction, and feedback. Copyright © 2014 Elsevier Inc. All rights reserved.

Climate Literacy: Supporting Teacher Professional Development

NASA Astrophysics Data System (ADS)

Haddad, N.; Ledley, T. S.; Dunlap, C.; Bardar, E.; Youngman, B.; Ellins, K. K.; McNeal, K. S.; Libarkin, J.

2012-12-01

Confronting the Challenges of Climate Literacy (CCCL) is an NSF-funded (DRK-12) project that includes curriculum development, teacher professional development, teacher leadership development, and research on student learning, all directed at high school teachers and students. The project's evaluation efforts inform and guide all major components of the project. The research effort addresses the question of what interventions are most effective in helping high school students grasp the complexities of the Earth system and climate processes, which occur over a range of spatial and temporal scales. The curriculum unit includes three distinct but related modules: Climate and the Cryosphere; Climate, Weather, and the Biosphere; and Climate and the Carbon Cycle. Climate-related themes that cut across all three modules include the Earth system, with the complexities of its positive and negative feedback loops; the range of temporal and spatial scales at which climate, weather, and other Earth system processes occur; and the recurring question, "How do we know what we know about Earth's past and present climate?" which addresses proxy data and scientific instrumentation. The professional development component of the project includes online science resources to support the teaching of the curriculum modules, summer workshops for high school teachers, and a support system for developing the teacher leaders who plan and implement those summer workshops. When completed, the project will provide a model high school curriculum with online support for implementing teachers and a cadre of leaders who can continue to introduce new teachers to the resource. This presentation will introduce the curriculum and the university partnerships that are key to the project's success, and describe how the project addresses the challenge of helping teachers develop their understanding of climate science and their ability to convey climate-related concepts articulated in the Next Generation

Theoretical analysis of polarization-coupled mode splitting in a single microfiber knot-ring resonator

NASA Astrophysics Data System (ADS)

Qiu, Weiqia; Zhou, Junjie; Yu, Jianhui; Xiao, Yi; Lu, Huihui; Guan, Heyuan; Zhong, Yongchun; Zhang, Jun; Chen, Zhe

2016-06-01

We established a theoretical model for a single knot-ring resonator and investigated the transmission spectrum by Jones matrix. The numerical results show that two orthogonal polarization modes of knot-ring, which are originally resonated at the same wavelength, will split into two resonant modes with different wavelengths. The mode splitting is due to the coupling between the two orthogonal polarization modes in the knot-ring when the twisted angle of the twist coupler is not exactly equal to 2mπ (m is an integer). It is also found that the separation of the mode splitting is linearly proportional to the deviation angle δθ with a high correlation coefficient of 99.6% and a slope of 3.17 nm/rad. Furthermore, a transparency phenomenon analogous to coupled-resonator-induced transparency was also predicted by the model. These findings may have potential applications in lasers and sensors.

Proof of Concept Study: Investigating Force Metrics of an Intracorporeal Suturing Knot Task.

PubMed

Wee, Justin; Azzie, Georges; Drake, James; Gerstle, J Ted

2018-06-19

Mastering proper force manipulation in minimally invasive surgery can take many hours of practice and training. Improper force control can lead to necrosis, infection, and scarring. A force-sensing skin (FSS) has been developed, which measures forces at the distal end of minimal access surgeries' (MAS) instruments without altering the instrument's structural integrity or the surgical workflow, and acts as a minimally disruptive add-on to any MAS instrument. A proof of concept study was conducted using a FSS-equipped 5 mm straight-tip needle holder. Participants (n = 19: 3 novices, 11 fellows, and 5 staff surgeons) performed one intracorporeal suturing knot task (ISKT). Using participant task video footage, each participant's two puncture forces (each wall of the Penrose drain) and three knot tightening forces were measured. Force metrics from the three expertise groups were compared using analysis of variance (ANOVA) and Tukey's honest significance test with statistical significance assessed at P < .05. Preliminary ISKT force metric data showed differences between novices and more experienced fellows and surgeons. Of the five stages of the ISKT evaluated, the first puncture force of the Penrose drain seemed to best reflect the difference in skill among participants. The study demonstrated ISKT knot tightening and puncture force ranges across three expertise levels (novices, surgical fellows, and staff surgeons) of 0.586 to 6.089 newtons (N) and 0.852 to 2.915 N, respectively. The investigation of force metrics is important for the implementation of future force feedback systems as it can provide real-time information to surgeons in training and the operating theater.

Unraveling the Helix Nebula: Its Structure and Knots

NASA Astrophysics Data System (ADS)

O'Dell, C. R.; McCullough, Peter R.; Meixner, Margaret

2004-11-01

Through Hubble Space Telescope (HST) imaging of the inner part of the main ring of the Helix Nebula, together with CTIO 4 m images of the fainter outer parts, we have a view of unprecedented quality of the nearest bright planetary nebula. These images have allowed us to determine that the main ring of the nebula is composed of an inner disk of about 499" diameter (0.52 pc) surrounded by an outer ring (in reality a torus) of 742" diameter (0.77 pc) whose plane is highly inclined to the plane of the disk. This outer ring is surrounded by an outermost ring of 1500" (1.76 pc) diameter, which is flattened on the side colliding with the ambient interstellar medium. The inner disk has an extended distribution of low-density gas along its rotational axis of symmetry, and the disk is optically thick to ionizing radiation, as is the outer ring. Published radial velocities of the knots provide support for the two-component structure of the main ring of the nebula and for the idea that the knots found there are expanding along with the nebular material from which they recently originated. These velocities indicate a spatial expansion velocity of the inner disk of 40 and 32 km s-1 for the outer ring, which yields expansion ages of 6560 and 12,100 yr, respectively. The outermost ring may be partially ionized through scattered recombination continuum from the inner parts of the nebula, but shocks certainly are occurring in it. This outermost ring probably represents a third period of mass loss by the central star. There is one compact, outer object that is unexplained, showing shock structures indicating a different orientation of the gas flow from that of the nebula. There is a change in the morphology of the knots as a function of the distance from the local ionization front. This supports a scenario in which the knots are formed in or near the ionization front and are then sculpted by the stellar radiation from the central star as the ionization front advances beyond them

EXPANSION OF HYDROGEN-POOR KNOTS IN THE BORN-AGAIN PLANETARY NEBULAE A30 AND A78

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, X.; Guerrero, M. A.; Marquez-Lugo, R. A.

2014-12-20

We analyze the expansion of hydrogen-poor knots and filaments in the born-again planetary nebulae A30 and A78 based on Hubble Space Telescope (HST) images obtained almost 20 yr apart. The proper motion of these features generally increases with distance to the central star, but the fractional expansion decreases, i.e., the expansion is not homologous. As a result, there is not a unique expansion age, which is estimated to be 610-950 yr for A30 and 600-1140 yr for A78. The knots and filaments have experienced complex dynamical processes: the current fast stellar wind is mass loaded by the material ablated from the inner knots;more » the ablated material is then swept up until it shocks the inner edges of the outer, hydrogen-rich nebula. The angular expansion of the outer filaments shows a clear dependence on position angle, indicating that the interaction of the stellar wind with the innermost knots channels the wind along preferred directions. The apparent angular expansion of the innermost knots seems to be dominated by the rocket effect of evaporating gas and by the propagation of the ionization front inside them. Radiation-hydrodynamical simulations show that a single ejection of material followed by a rapid onset of the stellar wind and ionizing flux can reproduce the variety of clumps and filaments at different distances from the central star found in A30 and A78.« less

A biomechanical study of laparoscopic 4S-modified Roeder and Weston knot strength in 3-0 polyglactin 910 and 3-0 polydioxanone.

PubMed

Fugazzi, Russell W; Fransson, Boel A; Curran, Katie M; Davis, Howard M; Gay, John M

2013-02-01

To (1) evaluate biomechanical strength of 4 different laparoscopic knots using 2 suture types, and (2) evaluate carotid artery ligature bursting pressure of 2 knots using a single suture type. Biomechanical materials testing. Suture material (3-0 polydioxanone, 3-0 polyglactin 910). Four knot types were tested: 4S-modified Roeder (4SMR) Weston plus 3 square throws (W3S); Weston plus 3 granny throws (W3G); and a 4 square throw knot as a control (control); 24 specimens of each knot type were tied with 3-0 polyglactin 910 and 24 of 3 knot types (4SMR, W3S, control) were tied with 3-0 polydioxanone. Suture loop constructs were tested to 3 mm displacement failure and ultimate failure. Carotid artery ligation bursting pressure was tested using 10 samples each of 4SMR and W3S knots with 3-0 polyglactin 910. The W3S, W3G, and controls were similar. The 4SMR was similar to W3S using 3-0 PDS but the 4SMR had lower load to failure and greater elongation than the Weston using 3-0 polyglactin 910. The 4SMR had a higher slippage rate with 3-0 polyglactin 910. All ligatures withstood supraphysiologic pressures. Surgeons using 3-0 polyglactin 910 should consider using the Weston knot with added throws during laparoscopic procedures. © Copyright 2012 by The American College of Veterinary Surgeons.

Comparative genomic analysis of the eight-membered ring cystine knot-containing bone morphogenetic protein antagonists.

PubMed

Avsian-Kretchmer, Orna; Hsueh, Aaron J W

2004-01-01

TGF-beta family proteins with a cystine knot motif serve as ligands for diverse families of plasma membrane receptors. Bone morphogenetic protein (BMP) antagonists represent a subgroup of these proteins, some of which bind BMPs and antagonize their actions during development and morphogenesis. Availability of completed genome sequences from diverse organisms allows bioinformatic analysis of the evolution of BMP antagonists and facilitates their classification. Using a regular expression algorithm (http://BioRegEx.stanford.edu), an exhaustive search of the human genome identified all cystine knot-containing BMP antagonists. Based on the size of the cystine ring, these proteins were divided into three subfamilies: CAN (eight-membered ring), twisted gastrulation (nine-membered ring), as well as chordin and noggin (10-membered ring). The CAN family can be divided further into four subgroups based on a conserved arrangement of additional cysteine residues-gremlin and PRDC, cerberus and coco, and DAN, together with USAG-1 and sclerostin. We searched for orthologs of human BMP antagonists in the genomes of model organisms and analyzed their phylogenetic relationship. New human paralogs were identified together with the verification of orthologous relationships of known genes. We also discuss the physiological roles of the CAN subfamily of BMP antagonists and the associated genetic defects. Based on the known three-dimensional structure of key cystine knot proteins, we postulated disulfide bondings for eight-membered ring BMP antagonists to predict their potential folding and dimerization.

Topologically knotted deubiquitinases exhibit unprecedented mechanostability to withstand the proteolysis by an AAA+ protease.

PubMed

Sriramoju, Manoj Kumar; Chen, Yen; Lee, Yun-Tzai Cloud; Hsu, Shang-Te Danny

2018-05-04

More than one thousand knotted protein structures have been identified so far, but the functional roles of these knots remain elusive. It has been postulated that backbone entanglement may provide additional mechanostability. Here, we employed a bacterial proteasome, ClpXP, to mechanically unfold 5 2 -knotted human ubiquitin C-terminal hydrolase (UCH) paralogs from their C-termini, followed by processive translocation into the proteolytic chamber for degradation. Our results revealed unprecedentedly slow kinetics of ClpXP-mediated proteolysis for the proteasome-associated UCHL5: ten thousand times slower than that of a green fluorescence protein (GFP), which has a comparable size to the UCH domain but much higher chemical and thermal stabilities. The ClpXP-dependent mechanostability positively correlates with the intrinsic unfolding rates of the substrates, spanning over several orders of magnitude for the UCHs. The broad range of mechanostability within the same protein family may be associated with the functional requirements for their differential malleabilities.

Wiggles and knots in radio jets

NASA Astrophysics Data System (ADS)

Trussoni, E.; Ferrari, A.; Zaninetti, L.

Dynamical effects in binary nuclei inside parent galactic cores, gravitational interactions with companion galaxies, and Kelvin-Helmholtz instabilities in the flow propagation have been proposed as mechanism responsible for the formation of the low amplitude morphologies, wiggles and knots, observed in radio jets. Here the basic characteristics and implications of these models are discussed with reference to the limited sample of existing data. In conclusion it will be shown that present observations cannot discriminate definitely these theories; conversely, different mechanisms may be at work together in any jet at the same time.

Measuring the thermal conductivity of individual carbon nanotubes by the Raman shift method.

PubMed

Li, Qingwei; Liu, Changhong; Wang, Xueshen; Fan, Shoushan

2009-04-08

The thermal contact resistance is a difficult problem that has puzzled many researchers in measuring the intrinsic thermal conductivity of an individual carbon nanotube (CNT). To avoid this problem, a non-contact Raman spectra shift method is introduced, by which we have successfully measured the thermal conductivity (kappa) of an individual single-walled carbon nanotube and a multi-walled carbon nanotube. The measured kappa values are 2400 W m(-1) K(-1) and 1400 W m(-1) K(-1), respectively. The CNT was suspended over a trench and heated by electricity. The temperature difference between the middle and the two ends of the CNT indicated its intrinsic heat transfer capability. The temperature difference was determined by the temperature-induced shifts of its G band Raman spectra. This new method can eliminate the impact of the thermal contact resistance which was a Gordian knot in many previous measurements.

The Origin of the Iron-Rich Knot in Tycho's Supernova Remnant

NASA Technical Reports Server (NTRS)

Yamaguchi, Hiroya; Hughes, John P.; Badenes, Carles; Bravo, Eduardo; Seitenzahl, Ivo R.; Martinez-Rodriguez, Hector; Park, Sangwook; Petre, Robert

2017-01-01

X-ray observations of supernova remnants (SNRs) allow us to investigate the chemical inhomogeneity of ejecta, offering unique insight into the nucleosynthesis in supernova explosions. Here we present detailed imaging and spectroscopic studies of the Fe knot located along the eastern rim of the Type Ia SNR Tycho ( SN 1572) using Suzaku and Chandra long-exposure data. Surprisingly, the Suzaku spectrum of this knot shows no emission from Cr, Mn, or Ni, which is unusual for the Fe-rich regions in this SNR. Within the framework of the canonical delayed-detonation models for SN Ia, the observed mass ratios M(sub Cr)/M(sub Fe) is less than 0.023, M(sub Mn)/M(sub Fe) is less than 0.012, and M(sub Ni)/M(sub Fe) is less than 0.029 (at 90% confidence) can only be achieved for a peak temperature of (5.3 - 5.7) x 10(exp. 9) K and a neutron excess of approximately less than 2.0 x 10(exp. -3). These constraints rule out the deep, dense core of a Chandrasekhar-mass white dwarf as the origin of the Fe knot and favor either incomplete Si burning or an Alpha-rich freeze-out regime, probably close to the boundary. An explosive He burning regime is a possible alternative, although this hypothesis is in conflict with the main properties of this SNR.

Habitat use by Red Knots (Calidris canutus rufa): Experiments with oyster racks and reefs on the beach and intertidal of Delaware Bay, New Jersey

NASA Astrophysics Data System (ADS)

Burger, Joanna; Niles, Lawrence J.

2017-07-01

Sea level rise and increasing human activities have decreased intertidal habitat in many places in the world. The expansion of aquaculture in intertidal areas may impact birds and other organisms using these habitats, leading to questions of sustainability of both aquaculture and functioning estuarine ecosystems. Understanding the effect of oyster culture on shorebird activity, particularly on Red Knots (Calidris canutus rufa), a species on the U.S. Threatened List, is important for adaptive management and the expansion of oyster culture. In May 2013 we experimentally compared Red Knot and shorebird use of a beach section with racks and a control, and in 2016 we compared the use of sections with artificial reefs, oyster racks, and control on Delaware Bay, New Jersey (USA). The data included only times when no workers or other people were present. Censuses, conducted every 30 min throughout the day (279 censuses in 2013, 231 censuses in 2016), included the number of Red Knots and other shorebirds in each treatment section. In 2013, the total number of shorebirds was significantly higher in the rack section than in the control section, except for Red Knots and Ruddy Turnstones (Arenaria interpres) that occurred in higher numbers in the control than in the rack section. In 2016 Red Knot numbers were also significantly lower in the rack section. In 2013, the mean number of Red Knots/census was 13 for racks vs 59 for the control (P < 0.0002). In 2016, the mean number of Red Knots/census was 13 for racks and over 68 for other treatments (P < 0.0001). Treatment, date, and number of non-Knot shorebirds explained 60% (2013) and 69% (2016) of the variation in Red Knot numbers. Red Knots avoided the sections with racks while both foraging and roosting, suggesting that caution should be used before placing oyster racks in areas used for foraging by Red Knots.

Disulfide bond rearrangement during formation of the chorionic gonadotropin beta-subunit cystine knot in vivo.

PubMed

Wilken, Jason A; Bedows, Elliott

2004-05-04

The intracellular kinetic folding pathway of the human chorionic gonadotropin beta-subunit (hCG-beta) reveals the presence of a disulfide between Cys residues 38-57 that is not detected by X-ray analysis of secreted hCG-beta. This led us to propose that disulfide rearrangement is an essential feature of cystine knot formation during CG-beta folding. To test this, we used disulfide bond formation to monitor progression of intracellular folding intermediates of a previously uncharacterized protein, the CG-beta subunit of cynomolgous macaque (Macaca fascicularis). Like its human counterpart hCG-beta with which it shares 81% identity, macaque (m)CG-beta is a cystine knot-containing subunit that assembles with an alpha-subunit common to all glycoprotein hormone members of its species to form a biologically active heterodimer, mCG, which, like hCG, is required for pregnancy maintenance. An early mCG-beta folding intermediate, mpbeta1, contained two disulfide bonds, one between Cys34 and Cys88 and the other between Cys38 and Cys57. The subsequent folding intermediate, mpbeta2-early, was represented by an ensemble of folding forms that, in addition to the two disulfides mentioned above, included disulfide linkages between Cys9 and Cys57 and between Cys38 and Cys90. These latter two disulfides are those contained within the beta-subunit cystine knot and reveal that a disulfide exchange occurred during the mpbeta2-early folding step leading to formation of the mCG-beta knot. Thus, while defining the intracellular kinetic protein folding pathway of a monkey homologue of CG-beta, we detected the previously predicted disulfide exchange event crucial for CG-beta cystine knot formation and attainment of CG-beta assembly competence.

Azadirachtin powder for control of root-knot nematodes in tomato

USDA-ARS?s Scientific Manuscript database

USDA ARS Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center, 64 Nowelo St., Hilo, HI 96720. Root-knot nematodes cause root galling and yield reductions in many vegetable crops, including tomato. Three organic treatments to improve root growth and reduce nematode infestation were eval...

Topological transformation of a trefoil knot into a [2]catenane.

PubMed

Prakasam, Thirumurugan; Bilbeisi, Rana A; El-Khoury, Roberto; Charbonnière, Loïc J; Elhabiri, Mourad; Esposito, Gennaro; Olsen, John-Carl; Trabolsi, Ali

2017-12-21

Topological transformation of a zinc-templated trefoil knot, Zn-TK, into a zinc-templated [2]catenane, Zn-[2]C, was studied. The net reaction 2 Zn-TK→3 Zn-[2]C was accomplished in 89% yield by heating a solution of Zn-TK in D 2 O. Kinetic investigation by 1 H NMR spectroscopy and high resolution mass spectrometry revealed that the mechanism is complex, involving a large pool of intermediates that form after imine bond cleavage. Bromide ions, which can occupy the central cavity of Zn-TK, inhibited the reaction. Two similar transformations were also studied, one of a cadmium-containing trefoil knot, Cd-TK, into a cadmium-containing catenane, Cd-[2]C, and the other of Cd-TK into Zn-[2]C. The latter transformation could be achieved in one step at high temperature or in two steps via transmetallation to form Zn-TK at room temperature followed by topological conversion of Zn-TK to Zn-[2]C at high temperature.

Design considerations for attaining 250-knot test velocities at the aircraft landing dynamics facility

NASA Technical Reports Server (NTRS)

Gray, C. E., Jr.; Snyder, R. E.; Taylor, J. T.; Cires, A.; Fitzgerald, A. L.; Armistead, M. F.

1980-01-01

Preliminary design studies are presented which consider the important parameters in providing 250 knot test velocities at the Aircraft Landing Dynamics Facility. Four major components of this facility are: the hydraulic jet catapult, the test carriage structure, the reaction turning bucket, and the wheels. Using the hydraulic-jet catapult characteristics, a target design point was selected and a carriage structure was sized to meet the required strength requirements. The preliminary design results indicate that to attain 250 knot test velocities for a given hydraulic jet catapult system, a carriage mass of 25,424 kg (56,000 lbm.) cannot be exceeded.

Climate change and sustainable development: realizing the opportunity.

PubMed

Robinson, John; Bradley, Mike; Busby, Peter; Connor, Denis; Murray, Anne; Sampson, Bruce; Soper, Wayne

2006-02-01

Manifold linkages exist between climate change and sustainable development. Although these are starting to receive attention in the climate exchange literature, the focus has typically been on examining sustainable development through a climate change lens, rather than vice versa. And there has been little systematic examination of how these linkages may be fostered in practice. This paper examines climate change through a sustainable development lens. To illustrate how this might change the approach to climate change issues, it reports on the findings of a panel of business, local government, and academic representatives in British Columbia, Canada, who were appointed to advise the provincial government on climate change policy. The panel found that sustainable development may offer a significantly more fruitful way to pursue climate policy goals than climate policy itself. The paper discusses subsequent climate change developments in the province and makes suggestions as how best to pursue such a sustainability approach in British Columbia and other jurisdictions.

Expansion of Hydrogen-poor Knots in the Born-again Planetary Nebulae A30 and A78

NASA Astrophysics Data System (ADS)

Fang, X.; Guerrero, M. A.; Marquez-Lugo, R. A.; Toalá, J. A.; Arthur, S. J.; Chu, Y.-H.; Blair, W. P.; Gruendl, R. A.; Hamann, W.-R.; Oskinova, L. M.; Todt, H.

2014-12-01

We analyze the expansion of hydrogen-poor knots and filaments in the born-again planetary nebulae A30 and A78 based on Hubble Space Telescope (HST) images obtained almost 20 yr apart. The proper motion of these features generally increases with distance to the central star, but the fractional expansion decreases, i.e., the expansion is not homologous. As a result, there is not a unique expansion age, which is estimated to be 610-950 yr for A30 and 600-1140 yr for A78. The knots and filaments have experienced complex dynamical processes: the current fast stellar wind is mass loaded by the material ablated from the inner knots; the ablated material is then swept up until it shocks the inner edges of the outer, hydrogen-rich nebula. The angular expansion of the outer filaments shows a clear dependence on position angle, indicating that the interaction of the stellar wind with the innermost knots channels the wind along preferred directions. The apparent angular expansion of the innermost knots seems to be dominated by the rocket effect of evaporating gas and by the propagation of the ionization front inside them. Radiation-hydrodynamical simulations show that a single ejection of material followed by a rapid onset of the stellar wind and ionizing flux can reproduce the variety of clumps and filaments at different distances from the central star found in A30 and A78. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program No. 12935.

Field level risk assessment for root-knot nematodes in lima beans

USDA-ARS?s Scientific Manuscript database

Southern Root-Knot Nematode (RKN), Meloidogyne incognita, is a major yield limiting pest in lima beans (Phaseolus lunatus). RKN are not evenly distributed through fields and population dynamics are fluid making whole field management challenging. The objectives of this research were to characterize ...

Characterization of bacterial knot disease caused by Pseudomonas savastanoi pv. savastanoi on pomegranate (Punica granatum L.) trees: a new host of the pathogen.

PubMed

Bozkurt, I A; Soylu, S; Mirik, M; Ulubas Serce, C; Baysal, Ö

2014-11-01

This study aimed to isolate and identify the causal organism causing hyperplastic outgrowths (knots) on stems and branches of pomegranate trees in the Eastern Mediterranean region of Turkey. Bacterial colonies were isolated from young knots on plates containing selective nutrient media. Biochemical tests, fatty acid analysis and PCR were performed to identify possible causal disease agent. Representative isolates were identified as Pseudomonas.pv.savastanoi (Psv) using biochemical tests, fatty acid profiling and PCR. Following inoculation of pomegranate plants (cv. hicaz) with bacterial suspensions, 25 of 54 bacterial isolates caused typical knots at the site of inoculation. PCR analysis, using specific primer for Psv, generated a single amplicon from all isolates. The similarity of the sequence of Turkish pomegranate isolate was 99% similar to the corresponding gene sequences of Psv in the databases. Based on symptoms, biochemical, molecular, pathogenicity tests and sequence analyses, the disease agent of knots observed on the pomegranate trees is Psv. To the best of our knowledge, this research has revealed pomegranate as a natural host of Psv, which extends the list of host plant species affected by the pathogen in the world and Turkey. Pomegranate trees were affected by the disease with outgrowths (galls or knot) disease. Currently, there is no published study on disease agent(s) causing the galls or knots on pomegranate trees in worldwide. Bacterial colonies were isolated from young knots. The causal agent of the knot Pseudomonas savastanoi pv.savastanoi (Psv) was identified based on symptoms, biochemical, molecular methods, pathogenicity tests and sequence analysis. To the best of our knowledge, this is the first report of Psv on pomegranate as a natural host, which extends the growing list of plant species affected by this bacterium in the world and Turkey. © 2014 The Society for Applied Microbiology.

[Good governance of publicly-produced health services: ideas for moving forward].

PubMed

Freire, José Manuel; Repullo, Jose Ramon

2011-06-01

The good performance of publicly-produced health services is of vital importance, well beyond the health sector. Taking into account the great complexity of the health services in the public sector due both to their public and professional nature, we identify seven Gordian Knots as being responsible for the most frequent problems of publicly produced health services in Spain and Latin America. From the concept of good governance we take its character as a normative and ethical benchmark and its potential to renew and invigorate the government of the public sector. From comparative analysis of publicly-produced health services in the best performing countries, we extract eight characteristics which contribute significantly to good performance. A final reflection is on the relevance of the importance of offsetting the potential hostility to a reformist impulse of the status-quo with alliances that strengthen public trust and the social contract between health professionals and citizens based on the values of public health systems.

Addressing climate challenges in developing countries

NASA Astrophysics Data System (ADS)

Tilmes, Simone; Monaghan, Andrew; Done, James

2012-04-01

Advanced Study Program/Early Career Scientist Assembly Workshop on Regional Climate Issues in Developing Countries; Boulder, Colorado, 19-22 October 2011 The Early Career Scientist Assembly (ECSA) and the Advanced Study Program of the National Center for Atmospheric Research (NCAR) invited 35 early-career scientists from nearly 20 countries to attend a 3-day workshop at the NCAR Mesa Laboratory prior to the World Climate Research Programme (WCRP) Open Science Conference in October 2011. The goal of the workshop was to examine a range of regional climate challenges in developing countries. Topics included regional climate modeling, climate impacts, water resources, and air quality. The workshop fostered new ideas and collaborations between early-career scientists from around the world. The discussions underscored the importance of establishing partnerships with scientists located in typically underrepresented countries to understand and account for the local political, economic, and cultural factors on which climate change is superimposed.

Shoulder abduction diminishes self-reinforcement in transosseous-equivalent rotator cuff repair in both knotted and knotless techniques.

PubMed

Smith, Geoffrey C S; Lam, Patrick H

2018-06-20

The self-reinforcement mechanism after double row suturebridge rotator cuff repair generates increasing compressive forces at the tendon footprint with increasing tendon load. Passive range of motion is usually allowed after rotator cuff repair. The mechanism of self-reinforcement could be adversely affected by shoulder abduction. Rotator cuff tears were created ex vivo in nine pairs of ovine shoulders. Two different repair techniques were used. One group was repaired using a double row 'suturebridge' construct with tied horizontal medial row mattress sutures (Knotted repair group). The other group was repaired identically except that medial row knots were not tied (Knotless repair group). Footprint compression was measured at varying amounts of abduction and under tendon loads of 0, 10, 20, 30, 40, 50 and 60N. The rate of increase of contact pressure (degree of self-reinforcement) was calculated for each abduction angle. Abduction diminishes footprint contact pressure in both knotted and knotless double row suturebridge constructs. Progressive abduction from 0 to 40 abduction in the knotless group and 0-30 in the knotted group results in a decrease in self-reinforcement. Abduction beyond this does not cause a further decrease in self-reinforcement. There was no difference in the rate of increase of footprint contact pressure at each angle of abduction when comparing the knotted and knotless groups. In the post-operative period, high tendon load combined with minimal abduction would be expected to generate the greatest amount of footprint compression which may improve tendon healing. Therefore, to maximize footprint compression the use of abduction pillows should be avoided while early isometric strengthening should be used.

Comparative analysis of the folding dynamics and kinetics of an engineered knotted protein and its variants derived from HP0242 of Helicobacter pylori

NASA Astrophysics Data System (ADS)

Wang, Liang-Wei; Liu, Yu-Nan; Lyu, Ping-Chiang; Jackson, Sophie E.; Hsu, Shang-Te Danny

2015-09-01

Understanding the mechanism by which a polypeptide chain thread itself spontaneously to attain a knotted conformation has been a major challenge in the field of protein folding. HP0242 is a homodimeric protein from Helicobacter pylori with intertwined helices to form a unique pseudo-knotted folding topology. A tandem HP0242 repeat has been constructed to become the first engineered trefoil-knotted protein. Its small size renders it a model system for computational analyses to examine its folding and knotting pathways. Here we report a multi-parametric study on the folding stability and kinetics of a library of HP0242 variants, including the trefoil-knotted tandem HP0242 repeat, using far-UV circular dichroism and fluorescence spectroscopy. Equilibrium chemical denaturation of HP0242 variants shows the presence of highly populated dimeric and structurally heterogeneous folding intermediates. Such equilibrium folding intermediates retain significant amount of helical structures except those at the N- and C-terminal regions in the native structure. Stopped-flow fluorescence measurements of HP0242 variants show that spontaneous refolding into knotted structures can be achieved within seconds, which is several orders of magnitude faster than previously observed for other knotted proteins. Nevertheless, the complex chevron plots indicate that HP0242 variants are prone to misfold into kinetic traps, leading to severely rolled-over refolding arms. The experimental observations are in general agreement with the previously reported molecular dynamics simulations. Based on our results, kinetic folding pathways are proposed to qualitatively describe the complex folding processes of HP0242 variants.

Prototype development of user specific climate services

NASA Astrophysics Data System (ADS)

Jacob, Daniela

2017-04-01

Systematic consultations in the last years with representatives from sectors particularly affected by climate change have helped the Climate Service Center Germany (GERICS) to identify the most pressing needs of stakeholders from public and private sectors. Besides the development of innovative climate service products and methods, areas are also identified, for which intensive research activities have to be initiated. An example is the demand of decision makers for high-resolution climate change information needed at regional to local levels for their activities towards climate change adaptation. For questions concerning adaptation to climate change, no standard solutions can be provided. Different from mitigation measures, adaptation measures must be framed in accordance with the specific circumstances prevailing in the local situation. Here, individual solutions, which satisfy the individual requirements and needs, are necessary. They have to be developed in close co-operation with the customers and users. For example, the implications of climate change on strategic and operative decisions, e.g. in enterprises and urban planning, are becoming increasingly important. Therefore, high-quality consultancy for businesses and public administration is needed, in order to support decision makers in identifying associated risks and opportunities. For the development of prototype products, GERICS has framed a general methodological approach, including the idea generation, the iterative development, and the prototype testing in co-development with the user. High process transparency and high product quality are prerequisite for the success of a product. The co-development process ensures the best possible communication of user tailored climate change information for different target groups.

Modified 16-Dot plication technique for correction of penile curvature: prevention of knot-related complications.

PubMed

Salem, Emad A

2018-05-08

Penile curvature is a common urological disease. Tunical plication for correction of penile curvature has been much popularized being simpler, adjustable to avoid overcorrection, less bleeding, and less postoperative erectile dysfunction. This study aims to assess the results of modified 16-dot plication technique for correction of congenital and acquired penile curvature and avoidance of knot-associated complications. Eighteen patients underwent correction of their penile curvature using the modified 16-dot plication technique between January 2014 and October 2015. Patients' pre and postoperative data were analyzed. The mean age of patients is 44 years old. Of the patients 15 who were available for follow-up, 8 patients had congenital penile curvature (CPC) and 7 had Peyronie's disease (PD). The angle of deviation ranged from 30° to 90°. Erectile function (EF) was assessed preoperative by IIEF score and duplex ultrasound. Postoperative follow-up at 3 and 6 months revealed straight erect penis in all patients. Longer follow-up at 1 to 2 years, 2 patients complained from slight recurrence of curve (<20°) and 2 patients complained of worsening of their erectile function. Penile shortening was noted by 6 patients. None of our patients stated any knot complication or bothersome, nor do hematomas, numbness, or painful erections. The modified 16-dot plication technique for correction if penile curvature is a safe and effective method. This modification allowed the knots to be tucked in the plicate tunical tissue avoiding knot-associated complications. More investigation on a large scale of patients or multicenter studies is recommended.

Hydrodynamic characteristics of knotted and knotless purse seine netting panels as determined in a flume tank

PubMed Central

Tang, Hao; Xu, Liuxiong; Hu, Fuxiang

2018-01-01

Nylon (PA) netting is widely used in purse seines and other fishing gears due to its high strength and good sinking performance. However, hydrodynamic properties of nylon netting of different characteristics are poorly understood. This study investigated hydrodynamic characteristics of nylon netting of different knot types and solidity ratios under different attack angles and flow velocities. It was found that the hydrodynamic coefficient of netting panels was related to Reynolds number, solidity ratio, attack angle, knot type and twine construction. The solidity ratio was found to positively correlate with drag coefficient when the netting was normal to the flow (CD90), but not the case when the netting was parallel to the flow (CD0). For netting panels inclined to the flow, the inclined drag coefficient had a negative relationship with the solidity ratio for attack angles between 0° and 50°, but a positive relationship for attack angles between 50° and 90°. The lift coefficient increased with the attack angle, reaching the culminating point at an attack angle of 50°, before subsequent decline. We found that the drag generated by knot accounted for 15–25% of total drag, and the knotted netting with higher solidity ratio exhibited a greater CD0, but it was not the case for the knotless netting. Compared to knotless polyethylene (PE) netting, the drag coefficients of knotless PA netting were dominant at higher Reynolds number (Re>2200). PMID:29420569

Hydrodynamic characteristics of knotted and knotless purse seine netting panels as determined in a flume tank.

PubMed

Tang, Hao; Xu, Liuxiong; Hu, Fuxiang

2018-01-01

Nylon (PA) netting is widely used in purse seines and other fishing gears due to its high strength and good sinking performance. However, hydrodynamic properties of nylon netting of different characteristics are poorly understood. This study investigated hydrodynamic characteristics of nylon netting of different knot types and solidity ratios under different attack angles and flow velocities. It was found that the hydrodynamic coefficient of netting panels was related to Reynolds number, solidity ratio, attack angle, knot type and twine construction. The solidity ratio was found to positively correlate with drag coefficient when the netting was normal to the flow (CD90), but not the case when the netting was parallel to the flow (CD0). For netting panels inclined to the flow, the inclined drag coefficient had a negative relationship with the solidity ratio for attack angles between 0° and 50°, but a positive relationship for attack angles between 50° and 90°. The lift coefficient increased with the attack angle, reaching the culminating point at an attack angle of 50°, before subsequent decline. We found that the drag generated by knot accounted for 15-25% of total drag, and the knotted netting with higher solidity ratio exhibited a greater CD0, but it was not the case for the knotless netting. Compared to knotless polyethylene (PE) netting, the drag coefficients of knotless PA netting were dominant at higher Reynolds number (Re>2200).

Evaluation of edible ginger and turmeric cultivars for root-knot nematode resistance

USDA-ARS?s Scientific Manuscript database

Edible ginger and turmeric roots are important agricultural commodities for the State of Hawaii. Bacterial wilt, Ralstonia solanacearum, and root-knot nematodes, Meloidogyne spp. are major factors hindering optimum production. An evaluation of tolerance and resistance to M. incognita was undertake...

Evaluation of nematicides for southern root-knot nematode management in lima bean

USDA-ARS?s Scientific Manuscript database

Southern root-knot nematodes (Meloidogyne incognita; RKN) significantly reduce lima bean (Phaseolus lunatus) yields. Chemical control options for RKN are limited. We evaluated the efficacy of new nematicidal products on RKN in lima bean experiments conducted in greenhouse (GH) and microplot (MP) set...

Examining the High-energy Radiation Mechanisms of Knots and Hotspots in Active Galactic Nucleus Jets

NASA Astrophysics Data System (ADS)

Zhang, Jin; Du, Shen-shi; Guo, Sheng-Chu; Zhang, Hai-Ming; Chen, Liang; Liang, En-Wei; Zhang, Shuang-Nan

2018-05-01

We compile the radio–optical–X-ray spectral energy distributions (SEDs) of 65 knots and 29 hotspots in 41 active galactic nucleus jets to examine their high-energy radiation mechanisms. Their SEDs can be fitted with the single-zone leptonic models, except for the hotspot of Pictor A and six knots of 3C 273. The X-ray emission of 1 hotspot and 22 knots is well explained as synchrotron radiation under the equipartition condition; they usually have lower X-ray and radio luminosities than the others, which may be due to a lower beaming factor. An inverse Compton (IC) process is involved for explaining the X-ray emission of the other SEDs. Without considering the equipartition condition, their X-ray emission can be attributed to the synchrotron-self-Compton process, but the derived jet powers (P jet) are not correlated with L k and most of them are larger than L k, with more than three orders of magnitude, where L k is the jet kinetic power estimated with their radio emission. Under the equipartition condition, the X-ray emission is well interpreted with the IC process for the cosmic microwave background photons (IC/CMB). In this scenario, the derived P jet of knots and hotspots are correlated with and comparable to L k. These results suggest that the IC/CMB model may be a promising interpretation of the X-ray emission. In addition, a tentative knot–hotspot sequence in the synchrotron peak-energy–peak-luminosity plane is observed, similar to the blazar sequence, which may be attributed to the different cooling mechanisms of electrons.

Climate Services for Development Planning and Implementation: A Framework for Assessing and Valuing Climate Services

NASA Astrophysics Data System (ADS)

Anderson, G.

2012-04-01

Climate Services for Development Planning and Implementation: A Framework for Assessing and Valuing Climate Services Anderson, Glen D. While weather forecasting products have been available globally for decades, the full suite of climate services - including historical and real time observational meteorological data, daily, weekly, and seasonal forecasts, and longer-term climate projections - has only been under development in the last 15 to 20 years. Climate services have been developed and implemented quite quickly in developed countries for public and private sector users. However, diffusion of these tools in developing countries has been slower for several reasons related to 1) lack of awareness of the opportunities and benefits of climate services; 2) spotty record of managing local weather and climate data; and 3) limited resources to build and sustain capacity in providing climate services. The Climate Services Partnership (CSP) was formed during the International Conference on Climate Services (ICCS) in October 2011. The CSP seeks to improve the provision and development of climate services worldwide. During the ICCS, three working groups were formed to carry out the work program of the CSP leading up to the second ICCS in Berlin in September 2012. The Economic Valuation of Climate Services Working Group, chaired by John Zillman and myself, is collaborating on several activities to demonstrate the benefits of climate services and help providers prioritize opportunities for expanding the use of climate services. The proposed paper will provide an overview of the Working Group's activities leading up to the next ICCS and describe specific work that is underway and expected to be completed prior to the EGU meetings. The focal point of the Working Group's activities is the development of matrix to help identify and value the best opportunities for using climate services. Different categories of climate services will be listed in rows and potential users of

Molecular characteristics and efficacy of 16D10 siRNAs in inhibiting root-knot nematode infection in transgenic grape hairy roots

USDA-ARS?s Scientific Manuscript database

Root-knot nematodes (RKNs) infect many annual and perennial crops and are the most devastating soil-born pests in vineyards. To develop a biotech-based solution for controlling RKNs in grapes, we evaluated the efficacy of plant-derived RNA interference (RNAi) silencing of a conserved RKN effector ge...

Developing Climate Resilience Toolkit Decision Support Training Sectio

NASA Astrophysics Data System (ADS)

Livezey, M. M.; Herring, D.; Keck, J.; Meyers, J. C.

2014-12-01

The Climate Resilience Toolkit (CRT) is a Federal government effort to address the U.S. President's Climate Action Plan and Executive Order for Climate Preparedness. The toolkit will provide access to tools and products useful for climate-sensitive decision making. To optimize the user experience, the toolkit will also provide access to training materials. The National Oceanic and Atmospheric Administration (NOAA) has been building a climate training capability for 15 years. The target audience for the training has historically been mainly NOAA staff with some modified training programs for external users and stakeholders. NOAA is now using this climate training capacity for the CRT. To organize the CRT training section, we collaborated with the Association of Climate Change Officers to determine the best strategy and identified four additional complimentary skills needed for successful decision making: climate literacy, environmental literacy, risk assessment and management, and strategic execution and monitoring. Developing the climate literacy skills requires knowledge of climate variability and change, as well as an introduction to the suite of available products and services. For the development of an environmental literacy category, specific topics needed include knowledge of climate impacts on specific environmental systems. Climate risk assessment and management introduces a process for decision making and provides knowledge on communication of climate information and integration of climate information in planning processes. The strategic execution and monitoring category provides information on use of NOAA climate products, services, and partnership opportunities for decision making. In order to use the existing training modules, it was necessary to assess their level of complexity, catalog them, and develop guidance for users on a curriculum to take advantage of the training resources to enhance their learning experience. With the development of this CRT

Developing Models for Predictive Climate Science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drake, John B; Jones, Philip W

2007-01-01

The Community Climate System Model results from a multi-agency collaboration designed to construct cutting-edge climate science simulation models for a broad research community. Predictive climate simulations are currently being prepared for the petascale computers of the near future. Modeling capabilities are continuously being improved in order to provide better answers to critical questions about Earth's climate. Climate change and its implications are front page news in today's world. Could global warming be responsible for the July 2006 heat waves in Europe and the United States? Should more resources be devoted to preparing for an increase in the frequency of strongmore » tropical storms and hurricanes like Katrina? Will coastal cities be flooded due to a rise in sea level? The National Climatic Data Center (NCDC), which archives all weather data for the nation, reports that global surface temperatures have increased over the last century, and that the rate of increase is three times greater since 1976. Will temperatures continue to climb at this rate, will they decline again, or will the rate of increase become even steeper? To address such a flurry of questions, scientists must adopt a systematic approach and develop a predictive framework. With responsibility for advising on energy and technology strategies, the DOE is dedicated to advancing climate research in order to elucidate the causes of climate change, including the role of carbon loading from fossil fuel use. Thus, climate science--which by nature involves advanced computing technology and methods--has been the focus of a number of DOE's SciDAC research projects. Dr. John Drake (ORNL) and Dr. Philip Jones (LANL) served as principal investigators on the SciDAC project, 'Collaborative Design and Development of the Community Climate System Model for Terascale Computers.' The Community Climate System Model (CCSM) is a fully-coupled global system that provides state-of-the-art computer simulations of

Extreme umbilical cord lengths, cord knot and entanglement: Risk factors and risk of adverse outcomes, a population-based study

PubMed Central

Kessler, Jörg

2018-01-01

Objectives To determine risk factors for short and long umbilical cord, entanglement and knot. Explore their associated risks of adverse maternal and perinatal outcome, including risk of recurrence in a subsequent pregnancy. To provide population based gestational age and sex and parity specific reference ranges for cord length. Design Population based registry study. Setting Medical Birth Registry of Norway 1999–2013. Population All singleton births (gestational age>22weeks<45 weeks) (n = 856 300). Methods Descriptive statistics and odds ratios of risk factors for extreme cord length and adverse outcomes based on logistic regression adjusted for confounders. Main outcome measures Short or long cord (<10th or >90th percentile), cord knot and entanglement, adverse pregnancy outcomes including perinatal and intrauterine death. Results Increasing parity, maternal height and body mass index, and diabetes were associated with increased risk of a long cord. Large placental and birth weight, and fetal male sex were factors for a long cord, which again was associated with a doubled risk of intrauterine and perinatal death, and increased risk of adverse neonatal outcome. Anomalous cord insertion, female sex, and a small placenta were associated with a short cord, which was associated with increased risk of fetal malformations, placental complications, caesarean delivery, non-cephalic presentation, perinatal and intrauterine death. At term, cord knot was associated with a quadrupled risk of perinatal death. The combination of a cord knot and entanglement had a more than additive effect to the association to perinatal death. There was a more than doubled risk of recurrence of a long or short cord, knot and entanglement in a subsequent pregnancy of the same woman. Conclusion Cord length is influenced both by maternal and fetal factors, and there is increased risk of recurrence. Extreme cord length, entanglement and cord knot are associated with increased risk of adverse

Direct Detection of the Helical Magnetic Field Geometry from 3D Reconstruction of Prominence Knot Trajectories

NASA Astrophysics Data System (ADS)

Zapiór, Maciej; Martínez-Gómez, David

2016-02-01

Based on the data collected by the Vacuum Tower Telescope located in the Teide Observatory in the Canary Islands, we analyzed the three-dimensional (3D) motion of so-called knots in a solar prominence of 2014 June 9. Trajectories of seven knots were reconstructed, giving information of the 3D geometry of the magnetic field. Helical motion was detected. From the equipartition principle, we estimated the lower limit of the magnetic field in the prominence to ≈1-3 G and from the Ampère’s law the lower limit of the electric current to ≈1.2 × 109 A.

A remarkably easy knot-tying technique for single-incision laparoscopic surgery with the SILS port for gynecologic diseases.

PubMed

Endo, Toshiaki; Nagasawa, Kunihiko; Umemura, Kota; Baba, Tsuyoshi; Henmi, Hirofumi; Saito, Tsuyoshi

2011-01-01

Single-incision laparoscopic surgery (SILS) has been quickly accepted, especially for women, because the cosmetic benefits may be greater than with ordinary laparoscopic surgery. In gynecologic disease, SILS is appropriate for diagnostic laparoscopy, oophorectomy, and salpingectomy, among other conditions. In addition, the knot-tying process for intracorporeal suturing during SILS is a major rate-limiting step and a key determinant of the popularity of SILS. Although a roticulator instrument is useful for creating the needed operative angle, knot tying is still believed to be difficult. We have devised a remarkably simple knot-tying technique that can be applied during SILS with a SILS Port with a Roticulator and a straight-type needle driver. We determined that, after transfixing the needle, the long tail of the thread should be grasped at around 90 degrees relative to the long axis of tip of the Roticulator, which is articulated at 80 degrees. This automatically forms an ideal C-loop because of gravitation. The needle attached to the long tail should face the distal side from the tip of Roticulator (from the surgeon's perspective). The apex of the C-loop is then toward the proximal side from the tip of the Roticulator (from the perspective of the surgeon). This thread position is important during the knot-tying process. The upper arm of the C-loop should then be entwined by applying a series of axial spinning movements to the rod of the needle driver. At this time, the jaws of the needle driver should be kept open so the thread does not slip off of the rod. The benefit of this technique is that it does not require any special skills; any surgeon able to perform intracorporeal suturing should also be able to easily tie knots during SILS. Copyright © 2011 AAGL. Published by Elsevier Inc. All rights reserved.

Prevention of suture knot exposure in posterior chamber intraocular lens implantation by 4-point scleral fixation technique.

PubMed

Baykara, Mehmet; Avci, Remzi

2004-01-01

The results and complications of posterior chamber intraocular lens (IOL) implantation by a 4-point scleral fixation technique are described. Fifty eyes of 47 patients who underwent scleral-fixated IOL implantation were retrospectively evaluated. Twenty-one (42%) eyes had a history of trauma and 29 (58%) eyes had previously undergone cataract surgery. In all cases, IOL implantation by 4-point scleral fixation was performed and the knots of fixation sutures were rotated and buried in the globe. The IOL position was adjusted by suture rotation for best centration. The mean follow-up time was 7 +/- 4 months. Four (8%) eyes had minimal corneal edema preoperatively. Cystoid macular edema was noted in 2 (6.8%) eyes in the cataract surgery group and 8 (38%) eyes in the posttraumatic group. Two (9.5%) eyes in the posttraumatic group had atrophic macular changes and 1 (4.7%) had corneal scarring, which impaired vision. No complications such as knot exposure, tilting of the IOL, decentralization, or endophthalmitis were noted postoperatively. Postoperative mean corrected visual acuity was 0.4 +/- 0.3 in the posttraumatic group and 0.4 +/- 0.2 in the cataract surgery group. The 4-point scleral fixation technique resulted in no serious postoperative complications such as suture exposure and endophthalmitis. Because the knot can be rotated and buried in the globe, knot exposure is less likely to occur. This procedure is more effective than other techniques regarding IOL centralization.

Identification of a novel putative signaling center, the tertiary enamel knot in the postnatal mouse molar tooth.

PubMed

Luukko, Keijo; Løes, Sigbjørn; Furmanek, Tomasz; Fjeld, Karianne; Kvinnsland, Inger Hals; Kettunen, Paivi

2003-03-01

The final shape of the molar tooth crown is thought to be regulated by the transient epithelial signaling centers in the cusp tips, the secondary enamel knots (SEKs), which are believed to disappear after initiation of the cusp growth. We investigated the developmental fate of the signaling center using the recently characterized Slit1 enamel knot marker as a lineage tracer during morphogenesis of the first molar and crown calcification in the mouse. In situ hybridization analysis showed that after Fgf4 downregulation in the SEK, Slit1 expression persisted in the deep compartment of the knot. After the histological disappearance of the SEK, Slit1 expression was evident in a novel epithelial cell cluster, which we call the tertiary enamel knot (TEK) next to the enamel-free area (EFA)-epithelium at the cusp tips. In embryonic tooth, Slit1 was also observed in the stratum intermedium (SI) and stellate reticulum cells between the parallel SEKs correlating to the area where the inner enamel epithelium cells do not proliferate. After birth, the expression of Slit1 persisted in the SI cells of the transverse connecting lophs of the parallel cusps above the EFA-cells. These results demonstrate the presence of a novel putative signaling center, the TEK, in the calcifying tooth. Moreover, our results suggest that Slit1 signaling may be involved in the regulation of molar tooth shape by regulating epithelial cell proliferation and formation of EFA of the crown.

Entrepreneurship Development and Business Climate of Kazakhstan

ERIC Educational Resources Information Center

Kydyrova, Zhamilya Sh.; Satymbekova, Katira B.; Kerimbek, Galymzhan E.; Imanbayev?, Zauresh O.; Saparbayev?, Saule S.; Nurgalieva, Ainash A.; Ilyas, Akylbek A.; Zhalbinova, Saule K.; Jrauovai, Kuralay S.; Kanafina, Ainura T.

2016-01-01

The goal is to explore the state of development of entrepreneurship and business climate for the formation of a clear mechanism of state support for small and average business in conditions of economy modernization. A special science-based methodology was developed to monitor the condition of entrepreneurship development and business climate in…

Clinical results of hamstring autografts in anterior cruciate ligament reconstruction: a comparison of femoral knot/press-fit fixation and interference screw fixation.

PubMed

Ho, Wei-Pin; Lee, Chian-Her; Huang, Chang-Hung; Chen, Chih-Hwa; Chuang, Tai-Yuan

2014-07-01

To compare the clinical outcomes of femoral knot/press-fit anterior cruciate ligament (ACL) reconstruction with conventional techniques using femoral interference screws. Among patients who underwent arthroscopic ACL reconstruction with hamstring autografts, 73 were treated with either a femoral knot/press-fit technique (40 patients, group A) or femoral interference screw fixation (33 patients, group B). The clinical results of the 2 groups were retrospectively compared. The inclusion criteria were primary ACL reconstruction in active patients. The exclusion criteria were fractures, multiligamentous injuries, patients undergoing revision, or patients with contralateral ACL-deficient knees. In the femoral knot/press-fit technique, semitendinosus and gracilis tendons were prepared as 2 loops with knots. After passage through a bottleneck femoral tunnel, the grafts were fixed with a press-fit method (grafts' knots were stuck in the bottleneck of the femoral tunnel). A tie with Mersilene tape (Ethicon, Somerville, NJ) over a bone bridge for each tendon loop and an additional bioabsorbable interference screw were used for tibial fixation. The mean follow-up period was 38 months (range, 24 to 61 months). A significant improvement in knee function and symptoms was reported in most patients, as shown by improved Tegner scores, Lysholm knee scores, and International Knee Documentation Committee assessments (P < .01). The results of instrumented laxity testing, thigh muscle assessment, and radiologic assessment were clearly improved when compared with the preoperative status (P < .01). No statistically significant difference in outcomes could be observed between group A and group B (P = not significant). In this nonrandomized study, femoral knot/press-fit ACL reconstruction did not appear to provide increased anterior instability compared with that of conventional femoral interference screw ACL reconstruction. Favorable outcomes with regard to knee stability and patient

The geometry of periodic knots, polycatenanes and weaving from a chemical perspective: a library for reticular chemistry.

PubMed

Liu, Yuzhong; O'Keeffe, Michael; Treacy, Michael M J; Yaghi, Omar M

2018-05-04

The geometry of simple knots and catenanes is described using the concept of linear line segments (sticks) joined at corners. This is extended to include woven linear threads as members of the extended family of knots. The concept of transitivity that can be used as a measure of regularity is explained. Then a review is given of the simplest, most 'regular' 2- and 3-periodic patterns of polycatenanes and weavings. Occurrences in crystal structures are noted but most structures are believed to be new and ripe targets for designed synthesis.

Sampling techniques and detection methods for developing risk assessments for root-knot nematode (Meloidogyne incognita) on lima bean (Phaseolus lunatus) in the Mid-Atlantic region

USDA-ARS?s Scientific Manuscript database

Lima bean, Phaseolus lunatus, is a cornerstone crop in the Mid-Atlantic region and Meloidogyne incognita, the southern root knot nematode (RKN), causes significant yield loss. The RKN has become more pervasive as toxic nematicides have been removed from the market, and risk evaluation research is ne...

Untying the Gordian knot of creation: metaphors for the Human Genome Project in Greek newspapers.

PubMed

Gogorosi, Eleni

2005-12-01

This article studies the metaphorical expressions used by newspapers to present the near completion of the Human Genome Project (HGP) to the Greek public in the year 2000. The analysis, based on cognitive metaphor theory, deals with the most frequent or captivating metaphors used to refer to the human genome, which give rise to both conventional and novel expressions. The majority of creative metaphorical expressions participate in the discourse of hope and promise propagated by the Greek media in an attempt to present the HGP and its outcome in a favorable light. Instances of the competing discourse of fear and danger are much rarer but can also be found in creative metaphorical expressions. Metaphors pertaining to the Greek culture or to ancient Greek mythology tend to carry a special rhetorical force. However, it will be shown that the Greek press strategically used most of the metaphors that circulated globally at the time, not only culture specific ones.

Gut Microbiomics-A Solution to Unloose the Gordian Knot of Biological Effects of Ionizing Radiation.

PubMed

Zhang, Amy; Steen, Tomoko Y

2018-02-14

The Chernobyl and Fukushima nuclear accidents have called forth a growing body of research on their biological aftermaths. A variety of wild organisms, including primates, birds, fish, insects, and worms are being studied in the affected areas, with emerging morphological, physiological, and genetic aberrations ascribed to ionizing radiation. Despite the effort in surveying Chernobyl and Fukushima wildlife, little is known about the microorganisms associated with these radiation-contaminated animals. The microbiota, especially the gut commensal, plays an important role in shaping the metabolic reservoir and immune system of the host, and is sensitive to a wide array of environmental factors, including ionizing radiation. Humans and limited numbers of laboratory species have been the main subjects of microbiome studies, however, a more practical insight on host-gut microbiota dynamics under environmental impact should be explored in natural habitats. In this analysis, we introduced a working model explaining possible mechanisms of ionizing radiation on the gut microbiota, with an evaluation of the gut microbiota as a potential biomarker for exposure to ionizing radiation. © The American Genetic Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

DEVELOPMENT OF IMPACT ORIENTED CLIMATE SCENARIOS

EPA Science Inventory

Appropriate scenarios of future climate must be developed prior to any assessment of the impacts of climate change. he information needed by impact assessors was examined in consultation with those having experience in scenario use. ost assessors require regional scenarios with a...

Economic development, climate and values: making policy.

PubMed

Stern, Nicholas

2015-08-07

The two defining challenges of this century are overcoming poverty and managing the risks of climate change. Over the past 10 years, we have learned much about how to tackle them together from ideas on economic development and public policy. My own work in these areas over four decades as an academic and as a policy adviser in universities and international financial institutions has focused on how the investment environment and the empowerment of people can change lives and livelihoods. The application of insights from economic development and public policy to climate change requires rigorous analysis of issues such as discounting, modelling the risks of unmanaged climate change, climate policy targets and estimates of the costs of mitigation. The latest research and results show that the case for avoiding the risks of dangerous climate change through the transition to low-carbon economic development and growth is still stronger than when the Stern Review was published. This is partly because of evidence that some of the impacts of climate change are happening more quickly than originally expected, and because of remarkable advances in technologies, such as solar power. Nevertheless, significant hurdles remain in securing the international cooperation required to avoid dangerous climate change, not least because of disagreements and misunderstandings about key issues, such as ethics and equity. © 2015 The Author(s).

Economic development, climate and values: making policy

PubMed Central

Stern, Nicholas

2015-01-01

The two defining challenges of this century are overcoming poverty and managing the risks of climate change. Over the past 10 years, we have learned much about how to tackle them together from ideas on economic development and public policy. My own work in these areas over four decades as an academic and as a policy adviser in universities and international financial institutions has focused on how the investment environment and the empowerment of people can change lives and livelihoods. The application of insights from economic development and public policy to climate change requires rigorous analysis of issues such as discounting, modelling the risks of unmanaged climate change, climate policy targets and estimates of the costs of mitigation. The latest research and results show that the case for avoiding the risks of dangerous climate change through the transition to low-carbon economic development and growth is still stronger than when the Stern Review was published. This is partly because of evidence that some of the impacts of climate change are happening more quickly than originally expected, and because of remarkable advances in technologies, such as solar power. Nevertheless, significant hurdles remain in securing the international cooperation required to avoid dangerous climate change, not least because of disagreements and misunderstandings about key issues, such as ethics and equity. PMID:26203007

Diversity of Knot Solitons in Liquid Crystals Manifested by Linking of Preimages in Torons and Hopfions

NASA Astrophysics Data System (ADS)

Ackerman, Paul J.; Smalyukh, Ivan I.

2017-01-01

Topological solitons are knots in continuous physical fields classified by nonzero Hopf index values. Despite arising in theories that span many branches of physics, from elementary particles to condensed matter and cosmology, they remain experimentally elusive and poorly understood. We introduce a method of experimental and numerical analysis of such localized structures in liquid crystals that, similar to the mathematical Hopf maps, relates all points of the medium's order parameter space to their closed-loop preimages within the three-dimensional solitons. We uncover a surprisingly large diversity of naturally occurring and laser-generated topologically nontrivial solitons with differently knotted nematic fields, which previously have not been realized in theories and experiments alike. We discuss the implications of the liquid crystal's nonpolar nature on the knot soliton topology and how the medium's chirality, confinement, and elastic anisotropy help to overcome the constraints of the Hobart-Derrick theorem, yielding static three-dimensional solitons without or with additional defects. Our findings will establish chiral nematics as a model system for experimental exploration of topological solitons and may impinge on understanding of such nonsingular field configurations in other branches of physics, as well as may lead to technological applications.

Video self-assessment of basic suturing and knot tying skills by novice trainees.

PubMed

Hu, Yinin; Tiemann, Debbie; Michael Brunt, L

2013-01-01

Self-assessment is important to learning but few studies have utilized video self-assessment of basic surgical skills. We compared a video self-assessment of suturing and knot tying skills by novice trainees to the assessment by a senior attending surgeon. Sixteen senior medical students and 7 beginner surgical interns were video-recorded while performing five suturing and knot tying tasks. All videos were analyzed using an objective structured assessment of technical skills (OSATS) metrics (1-5 scale; 1 = novice, 5 = expert). Video self-assessment was carried out within 4 weeks of an instructional session and subsequently by one senior surgery instructor (blinded to the individual). Both a Global score and total combined OSATS scores were analyzed. Total possible OSATS scores were: interrupted suture-30, subcuticular closure-30, one and two-handed knot tying-25 each, tying in a restricted space 20; maximum combined score-130 points). Confidence levels in performing the tasks pre-test and the value of video self-assessment were rated on a 1-5 Likert scale (1 = low and 5 = high). Data are mean±SD and statistical significance was evaluated using Friedman's test. Self-assessment scoring was significantly higher than the assessment by a senior instructor for three tasks by global score and all five tasks by combined OSATS score (self-assessment 71.8±16.7 vs attending assessment 56.7±11.0, p = 0.007). Mean self-assessment Global scores ranged from 2.5 to 2.8 for all tasks performed compared to 1.8-2.3 for attending surgeon assessment (p<0.05). Confidence levels demonstrated no correlation to performance speed or proficiency. The video self-assessment was rated as a highly valuable (mean 4.3±0.8) component to skills training. Novice trainees over-estimate their basic technical skills performance compared to the assessment by a senior surgeon. Video self-assessment may be a valuable addition to a pre-residency and surgical internship preparatory curriculum in basic

Synthetic electromagnetic knot in a three-dimensional skyrmion

PubMed Central

Lee, Wonjae; Gheorghe, Andrei H.; Tiurev, Konstantin; Ollikainen, Tuomas; Möttönen, Mikko; Hall, David S.

2018-01-01

Classical electromagnetism and quantum mechanics are both central to the modern understanding of the physical world and its ongoing technological development. Quantum simulations of electromagnetic forces have the potential to provide information about materials and systems that do not have conveniently solvable theoretical descriptions, such as those related to quantum Hall physics, or that have not been physically observed, such as magnetic monopoles. However, quantum simulations that simultaneously implement all of the principal features of classical electromagnetism have thus far proved elusive. We experimentally realize a simulation in which a charged quantum particle interacts with the knotted electromagnetic fields peculiar to a topological model of ball lightning. These phenomena are induced by precise spatiotemporal control of the spin field of an atomic Bose-Einstein condensate, simultaneously creating a Shankar skyrmion—a topological excitation that was theoretically predicted four decades ago but never before observed experimentally. Our results reveal the versatile capabilities of synthetic electromagnetism and provide the first experimental images of topological three-dimensional skyrmions in a quantum system. PMID:29511735

Climate volatility deepens poverty vulnerability in developing countries

NASA Astrophysics Data System (ADS)

Ahmed, Syud A.; Diffenbaugh, Noah S.; Hertel, Thomas W.

2009-07-01

Extreme climate events could influence poverty by affecting agricultural productivity and raising prices of staple foods that are important to poor households in developing countries. With the frequency and intensity of extreme climate events predicted to change in the future, informed policy design and analysis requires an understanding of which countries and groups are going to be most vulnerable to increasing poverty. Using a novel economic-climate analysis framework, we assess the poverty impacts of climate volatility for seven socio-economic groups in 16 developing countries. We find that extremes under present climate volatility increase poverty across our developing country sample—particularly in Bangladesh, Mexico, Indonesia, and Africa—with urban wage earners the most vulnerable group. We also find that global warming exacerbates poverty vulnerability in many nations.

Distributed Generation to Support Development-Focused Climate Action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cox, Sadie; Gagnon, Pieter; Stout, Sherry

2016-09-01

This paper explores the role of distributed generation, with a high renewable energy contribution, in supporting low emission climate-resilient development. The paper presents potential impacts on development (via energy access), greenhouse gas emission mitigation, and climate resilience directly associated with distributed generation, as well as specific actions that may enhance or increase the likelihood of climate and development benefits. This paper also seeks to provide practical and timely insights to support distributed generation policymaking and planning within the context of common climate and development goals as the distributed generation landscape rapidly evolves globally. Country-specific distributed generation policy and program examples,more » as well as analytical tools that can inform efforts internationally, are also highlighted throughout the paper.« less

Teachers Learning to Research Climate: Development of hybrid teacher professional development to support climate inquiry and research in the classroom

NASA Astrophysics Data System (ADS)

Odell, M. R.; Charlevoix, D. J.; Kennedy, T.

2011-12-01

The GLOBE Program is an international science and education focused on connecting scientists, teachers and students around relevant, local environmental issues. GLOBE's focus during the next two years in on climate, global change and understanding climate from a scientific perspective. The GLOBE Student Climate Research Campaign (SCRFC) will engage youth from around the world in understanding and researching climate through investigations of local climate challenges. GLOBE teachers are trained in implementation of inquiry in the classroom and the use of scientific data collection protocols to develop inquiry and research projects of the Earth System. In preparation for the SCRC, GLOBE teachers will need additional training in climate science, global change and communicating climate science in the classroom. GLOBE's reach to 111 countries around the world requires development of scalable models for training teachers. In June GLOBE held the first teacher professional development workshop (Learning to Research Summer Institute) in a hybrid format with two-thirds of the teachers participating face-to-face and the remaining teachers participating virtually using Adobe Connect. The week long workshop prepared teachers to integrate climate science inquiry and research projects in the classrooms in the 2011-12 academic year. GLOBE scientists and other climate science experts will work with teachers and their students throughout the year in designing and executing a climate science research project. Final projects and research results will be presented in May 2012 through a virtual conference. This presentation will provide the framework for hybrid teacher professional development in climate science research and inquiry projects as well as summarize the findings from this inaugural session. The GLOBE Program office, headquartered in Boulder, is funded through cooperative agreements with NASA and NOAA with additional support from NSF and the U.S. Department of State. GLOBE

RKVL-318, a root-knot nematode resistant rootstock line for grafted watermelon

USDA-ARS?s Scientific Manuscript database

The Agriculture Research Service, U.S. Department of Agriculture, announces the release of ‘RKVL-318’, a novel germplasm line useful as a rootstock and as a genetic resource for enhancing resistance to root-knot nematodes (RKN) in watermelon cultivars. ‘RKVL-318’ is derived from the wild-type water...

Managing root-knot nematodes: A case for cover crops in establishing peach orchards

USDA-ARS?s Scientific Manuscript database

Root-knot nematodes (Meloidogyne spp.) are an important pathogen of peach in the United States. Several Meloidogyne spp. have been reported to cause damage to stone fruits, but M. incognita and M. javanica are the predominant species on peach. Preplant fumigant nematicides have traditionally been ...

Potential of Neoactinolaimus as a biological control agent of root-knot and reniform nematodes

USDA-ARS?s Scientific Manuscript database

The predatory nematode Neoactinolaimus spp. (family Actinolaimidae) was examined as a potential biological control agent against root-knot (Meloidogyne spp.) and reniform (Rotylenchulus reniformis) nematodes in laboratory conditions. Neoactinolaimus possesses a large odontostylet to puncture the cu...

Rye residue levels affect suppression of the southern root-knot nematode in cotton

USDA-ARS?s Scientific Manuscript database

In the southeastern United States, rye (Secale cereale) is frequently planted as a winter cover crop in conservation tillage cotton. Although rye produces toxic benzoxazinoid compounds which may play a role in nematode suppression, it is also a host for the southern root-knot nematode Meloidogyne i...

Helicity conservation by flow across scales in reconnecting vortex links and knots

PubMed Central

Scheeler, Martin W.; Kleckner, Dustin; Kindlmann, Gordon L.; Irvine, William T. M.

2014-01-01

The conjecture that helicity (or knottedness) is a fundamental conserved quantity has a rich history in fluid mechanics, but the nature of this conservation in the presence of dissipation has proven difficult to resolve. Making use of recent advances, we create vortex knots and links in viscous fluids and simulated superfluids and track their geometry through topology-changing reconnections. We find that the reassociation of vortex lines through a reconnection enables the transfer of helicity from links and knots to helical coils. This process is remarkably efficient, owing to the antiparallel orientation spontaneously adopted by the reconnecting vortices. Using a new method for quantifying the spatial helicity spectrum, we find that the reconnection process can be viewed as transferring helicity between scales, rather than dissipating it. We also infer the presence of geometric deformations that convert helical coils into even smaller scale twist, where it may ultimately be dissipated. Our results suggest that helicity conservation plays an important role in fluids and related fields, even in the presence of dissipation. PMID:25326419

Relative humidity sensor based on a few-mode microfiber knot resonator by mitigating group index difference

NASA Astrophysics Data System (ADS)

Anh Le, Duy Duong; Lee, Seungmin; Han, Young-Geun

2017-04-01

A few-mode microfiber knot resonator (FM-MKR) incorporating a polyvinyl alcohol (PVA) is investigated for measurement of relative humidity (RH). Two modes, such as HE11 and HE12, are excited and interfered in a nonadiabatically tapered structure of the single-mode fiber (SMF). After making a tie with the few-mode microfiber, the FM-MKR is fabricated. In the FM-MKR, two modes, such as HE11 and HE12, must be circulated within the optical knot and cross-coupled independently with a phase delay. By optimizing the diameter of the microfiber, the difference of group effective refractive indices between two modes is dramatically suppressed resulting in the improvement of RH sensitivity of the proposed FM-MKR.

HOMFLY for twist knots and exclusive Racah matrices in representation [333

NASA Astrophysics Data System (ADS)

Morozov, A.

2018-03-01

Next step is reported in the program of Racah matrices extraction from the differential expansion of HOMFLY polynomials for twist knots: from the double-column rectangular representations R = [ rr ] to a triple-column and triple-hook R = [ 333 ]. The main new phenomenon is the deviation of the particular coefficient f[ 332 ][ 21 ] from the corresponding skew dimension, what opens a way to further generalizations.

Development of probabilistic regional climate scenario in East Asia

NASA Astrophysics Data System (ADS)

Dairaku, K.; Ueno, G.; Ishizaki, N. N.

2015-12-01

Climate information and services for Impacts, Adaptation and Vulnerability (IAV) Assessments are of great concern. In order to develop probabilistic regional climate information that represents the uncertainty in climate scenario experiments in East Asia (CORDEX-EA and Japan), the probability distribution of 2m air temperature was estimated by using developed regression model. The method can be easily applicable to other regions and other physical quantities, and also to downscale to finer-scale dependent on availability of observation dataset. Probabilistic climate information in present (1969-1998) and future (2069-2098) climate was developed using CMIP3 SRES A1b scenarios 21 models and the observation data (CRU_TS3.22 & University of Delaware in CORDEX-EA, NIAES AMeDAS mesh data in Japan). The prototype of probabilistic information in CORDEX-EA and Japan represent the quantified structural uncertainties of multi-model ensemble experiments of climate change scenarios. Appropriate combination of statistical methods and optimization of climate ensemble experiments using multi-General Circulation Models (GCMs) and multi-regional climate models (RCMs) ensemble downscaling experiments are investigated.

Chandra X-ray Observation of a Mature Cloud-Shock Interaction in the Bright Eastern Knot of Puppis A

NASA Technical Reports Server (NTRS)

Hwang, Una; Flanagan, Kathryn A.; Petre, Robert

2005-01-01

We present Chandra X-ray images and spectra of the most prominent cloud-shock interaction region in the Puppis A supernova remnant. The Bright Eastern Knot (BEK) has two main morphological components: (1) a bright compact knot that lies directly behind the apex of an indentation in the eastern X-ray boundary and (2) lying 1 westward behind the shock, a curved vertical structure (bar) that is separated from a smaller bright cloud (cap) by faint diffuse emission. Based on hardness images and spectra, we identify the bar and cap as a single shocked interstellar cloud. Its morphology strongly resembles the "voided sphere" structures seen at late times in Klein et al. experimental simulat.ions of cloud-shock interactions, when the crushing of the cloud by shear instabilities is well underway. We infer an intera.ction time of roughly cloud-crushing timescales, which translates to 2000-4000 years, based on the X-ray temperature, physical size, and estimated expansion of the shocked cloud. This is the first X-ray identified example of a cloud-shock interaction in this advanced phase. Closer t o the shock front, the X-ray emission of the compact knot in the eastern part of the BEK region implies a recent interaction with relatively denser gas, some of which lies in front of the remnant. The complex spatial relationship of the X-ray emission of the compact knot to optical [O III] emission suggests that there are multiple cloud interactions occurring along the line of sight.

Epidemiology and history of human parasitic diseases in Romania.

PubMed

Neghina, Raul; Neghina, Adriana M; Marincu, Iosif; Iacobiciu, Ioan

2011-06-01

Intestinal parasitic diseases such as enterobiasis, giardiasis, and ascariasis are detected most frequently in Romania, but their importance is definitely surpassed by trichinellosis, cystic echinococcosis, and toxoplasmosis. Malaria was common until its eradication in 1963, and only imported cases are reported nowadays. The aim of this review was to bring together essential data on the epidemiology and history of human parasitoses in Romania. Information on 43 parasitic diseases was collected from numerous sources, most of them unavailable abroad or inaccessible to the international scientific community. Over time, Romanian people of all ages have paid a significant tribute to the pathogenic influences exerted by the parasites. Sanitary and socio-economical consequences of the parasites diseases have great negative impact on the quality of life of affected individuals and the overall well-being of the population. Implementation of efficient public health measures and informative campaigns for the masses as well as changing the inadequate habits that are deeply rooted in the population are mandatory for cutting successfully this Gordian knot.

14 CFR 61.327 - How do I obtain privileges to operate a light-sport aircraft that has a VH greater than 87 knots...

Code of Federal Regulations, 2010 CFR

2010-01-01

... light-sport aircraft that has a VH greater than 87 knots CAS? 61.327 Section 61.327 Aeronautics and...: PILOTS, FLIGHT INSTRUCTORS, AND GROUND INSTRUCTORS Sport Pilots § 61.327 How do I obtain privileges to operate a light-sport aircraft that has a VH greater than 87 knots CAS? If you hold a sport pilot...

Initial description of primate-specific cystine-knot Prometheus genes and differential gene expansions of D-dopachrome tautomerase genes

PubMed Central

Premzl, Marko

2015-01-01

Using eutherian comparative genomic analysis protocol and public genomic sequence data sets, the present work attempted to update and revise two gene data sets. The most comprehensive third party annotation gene data sets of eutherian adenohypophysis cystine-knot genes (128 complete coding sequences), and d-dopachrome tautomerases and macrophage migration inhibitory factor genes (30 complete coding sequences) were annotated. For example, the present study first described primate-specific cystine-knot Prometheus genes, as well as differential gene expansions of D-dopachrome tautomerase genes. Furthermore, new frameworks of future experiments of two eutherian gene data sets were proposed. PMID:25941635

Complexity of bioindicator selection for ecological, human, and cultural health: Chinook salmon and red knot as case studies

PubMed Central

Burger, Joanna; Gochfeld, Michael; Niles, Lawrence; Powers, Charles; Brown, Kevin; Clarke, James; Dey, Amanda; Kosson, David

2015-01-01

There is considerable interest in developing bioindicators of ecological health that are also useful indicators for human health. Yet, human health assessment usually encompasses physical/chemical exposures and not cultural well-being. In this paper, we propose that bioindicators can be selected for all three purposes. We use Chinook or king salmon (Oncorhynchus tshawytscha) and red knot (Calidris canutus rufa, a sandpiper) as examples of indicators that can be used to assess human, ecological, and cultural health. Even so, selecting endpoints or metrics for each indicator species is complex and is explored in this paper. We suggest that there are several endpoint types to examine for a given species, including physical environment, environmental stressors, habitat, life history, demography, population counts, and cultural/societal aspects. Usually cultural endpoints are economic indicators (e.g., number of days fished, number of hunting licenses), rather than the importance of a fishing culture. Development of cultural/societal endpoints must include the perceptions of local communities, cultural groups, and tribal nations, as well as governmental and regulatory communities (although not usually so defined, the latter have cultures as well). Endpoint selection in this category is difficult because the underlying issues need to be identified and used to develop endpoints that tribes and stakeholders themselves see as reasonable surrogates of the qualities they value. We describe several endpoints for salmon and knots that can be used for ecological, human, and cultural/societal health. PMID:25666646

Complexity of bioindicator selection for ecological, human, and cultural health: Chinook salmon and red knot as case studies

DOE PAGES

Burger, Joanna; Gochfeld, Michael; Niles, Lawrence; ...

2015-02-10

There is considerable interest in developing bioindicators of ecological health that are also useful indicators for human health. Yet, human health assessment usually encompasses physical/chemical exposures and not cultural well-being. In this paper, we propose that bioindicators can be selected for all three purposes. We use Chinook or king salmon (Oncorhynchus tshawytscha) and red knot (Calidris canutus rufa, a sandpiper) as examples of indicators that can be used to assess human, ecological, and cultural health. Even so, selecting endpoints or metrics for each indicator species is complex and is explored in this paper. Here, we suggest that there are severalmore » endpoint types to examine for a given species, including physical environment, environmental stressors, habitat, life history, demography, population counts, and cultural/societal aspects. Usually cultural endpoints are economic indicators (e.g., number of days fished, number of hunting licenses), rather than the importance of a fishing culture. Development of cultural/societal endpoints must include the perceptions of local communities, cultural groups, and tribal nations, as well as governmental and regulatory communities (although not usually so defined, the latter have cultures as well). Endpoint selection in this category is difficult because the underlying issues need to be identified and used to develop endpoints that tribes and stakeholders themselves see as reasonable surrogates of the qualities they value. We describe several endpoints for salmon and knots that can be used for ecological, human, and cultural/societal health.« less

Complexity of bioindicator selection for ecological, human, and cultural health: Chinook salmon and red knot as case studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burger, Joanna; Gochfeld, Michael; Niles, Lawrence

There is considerable interest in developing bioindicators of ecological health that are also useful indicators for human health. Yet, human health assessment usually encompasses physical/chemical exposures and not cultural well-being. In this paper, we propose that bioindicators can be selected for all three purposes. We use Chinook or king salmon (Oncorhynchus tshawytscha) and red knot (Calidris canutus rufa, a sandpiper) as examples of indicators that can be used to assess human, ecological, and cultural health. Even so, selecting endpoints or metrics for each indicator species is complex and is explored in this paper. Here, we suggest that there are severalmore » endpoint types to examine for a given species, including physical environment, environmental stressors, habitat, life history, demography, population counts, and cultural/societal aspects. Usually cultural endpoints are economic indicators (e.g., number of days fished, number of hunting licenses), rather than the importance of a fishing culture. Development of cultural/societal endpoints must include the perceptions of local communities, cultural groups, and tribal nations, as well as governmental and regulatory communities (although not usually so defined, the latter have cultures as well). Endpoint selection in this category is difficult because the underlying issues need to be identified and used to develop endpoints that tribes and stakeholders themselves see as reasonable surrogates of the qualities they value. We describe several endpoints for salmon and knots that can be used for ecological, human, and cultural/societal health.« less

Developing perturbations for Climate Change Impact Assessments

NASA Astrophysics Data System (ADS)

Hewitson, Bruce

Following the 2001 Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report [TAR; IPCC, 2001], and the paucity of climate change impact assessments from developing nations, there has been a significant growth in activities to redress this shortcoming. However, undertaking impact assessments (in relation to malaria, crop stress, regional water supply, etc.) is contingent on available climate-scale scenarios at time and space scales of relevance to the regional issues of importance. These scales are commonly far finer than even the native resolution of the Global Climate Models (GCMs) (the principal tools for climate change research), let alone the skillful resolution (scales of aggregation at which GCM observational error is acceptable for a given application) of GCMs.Consequently, there is a growing demand for regional-scale scenarios, which in turn are reliant on techniques to downscale from GCMs, such as empirical downscaling or nested Regional Climate Models (RCMs). These methods require significant skill, experiential knowledge, and computational infrastructure in order to derive credible regional-scale scenarios. In contrast, it is often the case that impact assessment researchers in developing nations have inadequate resources with limited access to scientists in the broader international scientific community who have the time and expertise to assist. However, where developing effective downscaled scenarios is problematic, it is possible that much useful information can still be obtained for impact assessments by examining the system sensitivity to largerscale climate perturbations. Consequently, one may argue that the early phase of assessing sensitivity and vulnerability should first be characterized by evaluation of the first-order impacts, rather than immediately addressing the finer, secondary factors that are dependant on scenarios derived through downscaling.

Inspiring Climate Education Excellence(ICEE): Developing Elearning professional development modules - secondary science teachers

NASA Astrophysics Data System (ADS)

Kellagher, E.; Buhr, S. M.; Lynds, S. E.; McCaffrey, M. S.; Cires Education Outreach

2011-12-01

Inspiring Climate Education Excellence (ICEE) is a NASA-funded project to develop content knowledge and knowledge of effective teaching strategies in climate education among secondary science teachers. ICEE resources are aligned with the Essential Principles of Climate Science. Building upon a needs assessment and face to face workshop, ICEE resources include iTunesU videos, an ICEE 101 resource site with videos and peer-reviewed learning activities, and a moderated online forum. Self-directed modules and an online course are being developed around concepts and topics in which teachers express the most interest and need for instruction. ICEE resources include attention to effective teaching strategies, such as awareness of student misconceptions, strategies for forestalling controversy and advice from master teachers on implementation and curriculum development. The resources are being developed in partnership with GLOBE, and the National Science Digital Library (NSDL) and are informed by the work of the Climate Literacy and Energy Awareness Network (CLEAN) project. ICEE will help to meet the professional development needs of teachers, including those participating in the GLOBE Student Climate Research Campaign.

Development of a Climate Resilience Screening Index (CRSI) ...

EPA Pesticide Factsheets

A Climate Resilience Screening Index is being developed that is applicable at multiple scales for the United States. Those scales include national, state, county and community. The index will be applied at the first three scales and at selected communities. The index was developed in order to explicitly include domains, indicators and metrics addressing environmental, economic and societal aspects of climate resilience. In addition, the index uses indicators and metrics that assess ecosystem, economic, governance and social services at these scales. Finally, we are developing forecasting approaches that can relate intended changes in services and governance to likely levels of changes in the resiliency of communities to climate change impacts. The present challenge is the incorporation of the index, its relationships to governance and the developing forecasting tools into Federal decision-making across US government and into state/county/community decision-making across the US. Governmental acceptance of changes to policies often can be just as challenging as the initial technical acceptance of the index and its relation to climate change. Climate Resilience Index is a requested product by ORD AA and EPA Administrator through SHC Program. Index needed to assess states', counties', and communities' abilities of recovery from climate events. Audience: Internal EPA (Administrator, IO, OLEM, OW and OAR) and external (states, counties and communities). Product

Root-knot nematodes in golf course greens of the western United States

USDA-ARS?s Scientific Manuscript database

A survey of 238 golf courses in ten of the Western U.S. found root-knot nematodes (Meloidogyne spp.) in 60 % of the putting greens sampled. Sequence and phylogenetic analyses of 18S rRNA, D2-D3 of 28S rRNA, ITS-rRNA and mtDNA gene sequences were used to identify specimens from 110 golf courses. The...

Expression of the KNOTTED HOMEOBOX Genes in the Cactaceae Cambial Zone Suggests Their Involvement in Wood Development.

PubMed

Reyes-Rivera, Jorge; Rodríguez-Alonso, Gustavo; Petrone, Emilio; Vasco, Alejandra; Vergara-Silva, Francisco; Shishkova, Svetlana; Terrazas, Teresa

2017-01-01

The vascular cambium is a lateral meristem that produces secondary xylem (i.e., wood) and phloem. Different Cactaceae species develop different types of secondary xylem; however, little is known about the mechanisms underlying wood formation in the Cactaceae. The KNOTTED HOMEOBOX (KNOX) gene family encodes transcription factors that regulate plant development. The role of class I KNOX genes in the regulation of the shoot apical meristem, inflorescence architecture, and secondary growth is established in a few model species, while the functions of class II KNOX genes are less well understood, although the Arabidopsis thaliana class II KNOX protein KNAT7 is known to regulate secondary cell wall biosynthesis. To explore the involvement of the KNOX genes in the enormous variability of wood in Cactaceae, we identified orthologous genes expressed in species with fibrous ( Pereskia lychnidiflora and Pilosocereus alensis ), non-fibrous ( Ariocarpus retusus ), and dimorphic ( Ferocactus pilosus ) wood. Both class I and class II KNOX genes were expressed in the cactus cambial zone, including one or two class I paralogs of KNAT1 , as well as one or two class II paralogs of KNAT3 - KNAT4 - KNAT5 . While the KNOX gene SHOOTMERISTEMLESS ( STM) and its ortholog ARK1 are expressed during secondary growth in the Arabidopsis and Populus stem, respectively, we did not find STM orthologs in the Cactaceae cambial zone, which suggests possible differences in the vascular cambium genetic regulatory network in these species. Importantly, while two class II KNOX paralogs from the KNAT7 clade were expressed in the cambial zone of A. retusus and F. pilosus , we did not detect KNAT7 ortholog expression in the cambial zone of P. lychnidiflora . Differences in the transcriptional repressor activity of secondary cell wall biosynthesis by the KNAT7 orthologs could therefore explain the differences in wood development in the cactus species.

Expression of the KNOTTED HOMEOBOX Genes in the Cactaceae Cambial Zone Suggests Their Involvement in Wood Development

PubMed Central

Reyes-Rivera, Jorge; Rodríguez-Alonso, Gustavo; Petrone, Emilio; Vasco, Alejandra; Vergara-Silva, Francisco; Shishkova, Svetlana; Terrazas, Teresa

2017-01-01

The vascular cambium is a lateral meristem that produces secondary xylem (i.e., wood) and phloem. Different Cactaceae species develop different types of secondary xylem; however, little is known about the mechanisms underlying wood formation in the Cactaceae. The KNOTTED HOMEOBOX (KNOX) gene family encodes transcription factors that regulate plant development. The role of class I KNOX genes in the regulation of the shoot apical meristem, inflorescence architecture, and secondary growth is established in a few model species, while the functions of class II KNOX genes are less well understood, although the Arabidopsis thaliana class II KNOX protein KNAT7 is known to regulate secondary cell wall biosynthesis. To explore the involvement of the KNOX genes in the enormous variability of wood in Cactaceae, we identified orthologous genes expressed in species with fibrous (Pereskia lychnidiflora and Pilosocereus alensis), non-fibrous (Ariocarpus retusus), and dimorphic (Ferocactus pilosus) wood. Both class I and class II KNOX genes were expressed in the cactus cambial zone, including one or two class I paralogs of KNAT1, as well as one or two class II paralogs of KNAT3-KNAT4-KNAT5. While the KNOX gene SHOOTMERISTEMLESS (STM) and its ortholog ARK1 are expressed during secondary growth in the Arabidopsis and Populus stem, respectively, we did not find STM orthologs in the Cactaceae cambial zone, which suggests possible differences in the vascular cambium genetic regulatory network in these species. Importantly, while two class II KNOX paralogs from the KNAT7 clade were expressed in the cambial zone of A. retusus and F. pilosus, we did not detect KNAT7 ortholog expression in the cambial zone of P. lychnidiflora. Differences in the transcriptional repressor activity of secondary cell wall biosynthesis by the KNAT7 orthologs could therefore explain the differences in wood development in the cactus species. PMID:28316604

Ultrasonic detection of knots, cross grain and bark pockets in wooden pallet parts

Treesearch

Mohammed F. Kabir; Daniel L. Schmoldt; Mark E. Schafer

2000-01-01

This study investigates defect detection in wooden pallet parts using ultrasonic scanning. Yellow-poplar (Liriodendron tulipifera, L.) deckboards were scanned using two rolling transducers in a pitch-catch arrangement to detect unsound and sound knots, bark pockets and cross grain. Data were collected, stored, and processed using LabView? software. Six ultrasonic...

Outstanding challenges limiting the development of climate services in Europe

NASA Astrophysics Data System (ADS)

Buontempo, Carlo; Soares, Marta Bruno; Liggins, Felicity

2016-04-01

Climate services attempt to make the available (or forthcoming) climate knowledge more usable by decision and policy makers in the development of a climate smart society. Since the launch of the Global Framework for Climate Services in 2009 there has been an exponential increase in investment in the development and delivery of climate services, leading to an array of projects and initiatives across Europe. However, to date little attention has been given to understanding the different ways in which climate services are defined, implemented, and evaluated in Europe. In addition, other aspects such as how to pursue the necessary processes of co-production, which business models to apply, and the implications for the careers of scientists and others involved in the development of climate services are also crucial elements that need to be further examined and discussed. Such aspects are critical to the future development of climate services as they have the potential to significantly constrain the growth of climate services in Europe. Starting from a set of questions that have arisen within some of the most prominent climate services projects and initiatives in Europe, our paper highlights and expands on the outstanding challenges that need to be resolved by both the scientific community and the funders in order to ensure climate services can prosper and grow in Europe.

Resistance of upland-rice lines to root-knot nematode, Meloidogyne incognita.

PubMed

Souza, D C T; Botelho, F B S; Rodrigues, C S; Furtini, I V; Smiderle, E C; de Matos, D L; Bruzi, A T

2015-12-21

Despite the benefits of crop rotation, occurrence of nematodes is a common problem for almost all crops within the Cerrado biome, especially for rice. The use of resistant cultivars is one of the main methods for control of nematodes. Thus, the present study aimed to evaluate the reaction of 36 upland-rice lines, with desirable agronomic characteristics, according to their resistance to root-knot nematodes (Meloidogyne incognita). The experimental design was entirely randomized with four replications. Each plot of land consisted of two rice plants in a 3-L vase. The plants were inoculated with 1000 eggs and eventual juveniles of the respective nematodes. Fifty-five days after the inoculation, the roots and the aerial part of the plant were weighed and the egg mass (EM) as well as the reproduction factor (Rf) were estimated. It was determined that the isolated use of EM was not beneficial in selecting rice lines resistant to the root-knot nematode. This procedure must, therefore, take into account the egg counting and the Rf, in order to improve the reliability of the selection. In our study, 30 evaluated lines were observed to be resistant. Among the recommended cultivars, only BRS Monarca had its performance susceptible to the studied nematode species.

Resistant Citrullus lanatus var. citroides Rootstocks for Managing Root-knot Nematodes in Grafted Watermelon

USDA-ARS?s Scientific Manuscript database

Southern root-knot nematode (RKN), Meloidogyne incognita, is an important re-emerging pest of watermelon. Several factors have contributed to re-emergence of RKN including: 1) ban of methyl bromide for soil fumigation; 2) reduced land area for crop rotation; and 3) continuous cropping of cucurbits u...

Mustard seed meal for management of root-knot nematode and weeds in tomato production

USDA-ARS?s Scientific Manuscript database

Mustard seed meals of indian mustard [InM (Brassica juncea)] and yellow mustard [YeM (Sinapis alba)], alone and combined, were tested for effects on tomato (Solanum lycopersicum) plants and for suppression of southern root-knot nematode [RKN (Meloidogyne incognita)] and weed populations. In the gree...

Integrated management of root-knot nematode, Meloidogyne incognita infestation in tomato and grapevine.

PubMed

Kumari, N Swarna; Sivakumar, C V

2005-01-01

An integrated approach with the obligate bacterial parasite, Pasteuria penetrans and nematicides was assessed for the management of the root-knot nematode, Meloidogyne incognita infestation in tomato and grapevine. Seedlings of tomato cv. Co3 were transplanted into pots filled with sterilized soil and inoculated with nematodes (5000 juveniles/pot). The root powder of P. penetrans at 10 mg/pot was applied alone and in combination with carbofuran at 6 mg/pot. Application of P. penetrans along with carbofuran recorded lowest nematode infestation (107 nematodes/200 g soil) compared to control (325 nematodes/200 g soil). The rate of parasitization was 83.1% in the carbofuran and P. penetrans combination treatment as against 61.0% in the P. penetrans treatment only. The plant growth was also higher in the combination treatment compared to all other treatments. A field trial was carried out to assess the efficacy of P. penetrans and nematicides viz., carbofuran and phorate in the management of root-knot nematode, M. incognita infestation of grapevine cv. Muscat Hamburg. A nematode and P. penetrans infested grapevine field was selected and treatments either with carbofuran or phorate at 1 g a.i/vine was given. The observations were recorded at monthly interval. The results showed that the soil nematode population was reduced in nematicide treated plots. Suppression of nematodes was higher under phorate (117 nematodes/200 g soil) than under carbofuran (126.7 nematodes/200 g soil) treatment. The number of juveniles parasitized was also influenced by nematicides and spore load carried/juvenile with phorate being superior and the increase being 17.0 and 29.0% respectively over the control. The results of these experiment confirmed the compatibility of P. penetrans with nematicides and its biological control potential against the root-knot nematode.

Torus Knot Polynomials and Susy Wilson Loops

NASA Astrophysics Data System (ADS)

Giasemidis, Georgios; Tierz, Miguel

2014-12-01

We give, using an explicit expression obtained in (Jones V, Ann Math 126:335, 1987), a basic hypergeometric representation of the HOMFLY polynomial of ( n, m) torus knots, and present a number of equivalent expressions, all related by Heine's transformations. Using this result, the symmetry and the leading polynomial at large N are explicit. We show the latter to be the Wilson loop of 2d Yang-Mills theory on the plane. In addition, after taking one winding to infinity, it becomes the Wilson loop in the zero instanton sector of the 2d Yang-Mills theory, which is known to give averages of Wilson loops in = 4 SYM theory. We also give, using matrix models, an interpretation of the HOMFLY polynomial and the corresponding Jones-Rosso representation in terms of q-harmonic oscillators.

Biochemical and MALDI-TOF Mass Spectrometric Characterization of a Novel Native and Recombinant Cystine Knot Miniprotein from Solanum tuberosum subsp. andigenum cv. Churqueña

PubMed Central

Cotabarren, Juliana; Tellechea, Mariana Edith; Tanco, Sebastián Martín; Garcia-Pardo, Javier; Avilés, Francesc Xavier; Obregón, Walter David

2018-01-01

Cystine-knot miniproteins (CKMPs) are an intriguing group of cysteine-rich molecules that combine the characteristics of proteins and peptides. Typically, CKMPs are fewer than 50 residues in length and share a characteristic knotted scaffold characterized by the presence of three intramolecular disulfide bonds that form the singular knotted structure. The knot scaffold confers on these proteins remarkable chemical, thermal, and proteolytic stability. Recently, CKMPs have emerged as a novel class of natural molecules with interesting pharmacological properties. In the present work, a novel cystine-knot metallocarboxypeptidase inhibitor (chuPCI) was isolated from tubers of Solanum tuberosum, subsp. andigenum cv. Churqueña. Our results demonstrated that chuPCI is a member of the A/B-type family of metallocarboxypeptidases inhibitors. chuPCI was expressed and characterized by a combination of biochemical and mass spectrometric techniques. Direct comparison of the MALDI-TOF mass spectra for the native and recombinant molecules allowed us to confirm the presence of four different forms of chuPCI in the tubers. The majority of such forms have a molecular weight of 4309 Da and contain a cyclized Gln in the N-terminus. The other three forms are derived from N-terminal and/or C-terminal proteolytic cleavages. Taken together, our results contribute to increase the current repertoire of natural CKMPs. PMID:29495576

Implications of climate change mitigation for sustainable development

NASA Astrophysics Data System (ADS)

Jakob, Michael; Steckel, Jan Christoph

2016-10-01

Evaluating the trade-offs between the risks related to climate change, climate change mitigation as well as co-benefits requires an integrated scenarios approach to sustainable development. We outline a conceptual multi-objective framework to assess climate policies that takes into account climate impacts, mitigation costs, water and food availability, technological risks of nuclear energy and carbon capture and sequestration as well as co-benefits of reducing local air pollution and increasing energy security. This framework is then employed as an example to different climate change mitigation scenarios generated with integrated assessment models. Even though some scenarios encompass considerable challenges for sustainability, no scenario performs better or worse than others in all dimensions, pointing to trade-offs between different dimensions of sustainable development. For this reason, we argue that these trade-offs need to be evaluated in a process of public deliberation that includes all relevant social actors.

78 FR 4132 - National Climate Assessment and Development Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-18

...-3013-0] RIN 0648-XC433 National Climate Assessment and Development Advisory Committee AGENCY: Office of... Oceanic and Atmospheric Research (OAR) publishes this notice on behalf of the National Climate Assessment and Development Advisory Committee (NCADAC) to announce the availability of a Draft Climate Assessment...

Polymer Uncrossing and Knotting in Protein Folding, and Their Role in Minimal Folding Pathways

PubMed Central

Mohazab, Ali R.; Plotkin, Steven S.

2013-01-01

We introduce a method for calculating the extent to which chain non-crossing is important in the most efficient, optimal trajectories or pathways for a protein to fold. This involves recording all unphysical crossing events of a ghost chain, and calculating the minimal uncrossing cost that would have been required to avoid such events. A depth-first tree search algorithm is applied to find minimal transformations to fold , , , and knotted proteins. In all cases, the extra uncrossing/non-crossing distance is a small fraction of the total distance travelled by a ghost chain. Different structural classes may be distinguished by the amount of extra uncrossing distance, and the effectiveness of such discrimination is compared with other order parameters. It was seen that non-crossing distance over chain length provided the best discrimination between structural and kinetic classes. The scaling of non-crossing distance with chain length implies an inevitable crossover to entanglement-dominated folding mechanisms for sufficiently long chains. We further quantify the minimal folding pathways by collecting the sequence of uncrossing moves, which generally involve leg, loop, and elbow-like uncrossing moves, and rendering the collection of these moves over the unfolded ensemble as a multiple-transformation “alignment”. The consensus minimal pathway is constructed and shown schematically for representative cases of an , , and knotted protein. An overlap parameter is defined between pathways; we find that proteins have minimal overlap indicating diverse folding pathways, knotted proteins are highly constrained to follow a dominant pathway, and proteins are somewhere in between. Thus we have shown how topological chain constraints can induce dominant pathway mechanisms in protein folding. PMID:23365638

Nematicidal fluorescent pseudomonads for the in vitro and in vivo suppression of root knot (Meloidogyne incognita) of Capsicum annuum L.

PubMed

Wahla, Verinder; Maheshwari, Dinesh K; Bajpai, Vivek K

2012-08-01

Considerable attention has been paid to plant-growth-promoting rhizobacteria (PGPR), especially the fluorescent group of Pseudomonas species, as the best alternatives to chemicals for facilitating ecofriendly biological control of soil- and seedborne microorganisms. On the basis of their novel plant-growth-promoting attributes, two rhizobacteria Pseudomonas aeruginosa VP1 and VP2 selected out of over 63 isolates from the rhizosphere of chilli (Capsicum annuum) were identified as potential candidates for biocontrol of the root-knot nematode Meloidogyne incognita on chilli. The nematicidal activity of both strains was evaluated in vitro and in vivo for their efficacy against M. incognita. P. aeruginosa VP2 exhibited strong nematicidal activity in comparison with VP1, based on the in vitro killing of the second-stage juveniles (J2) of M. incognita. Seed bacterisation with both strains VP1 and VP2 was able to manage root-knot M. incognita on chilli (C. annuum) in a pot trial study. Increase in root and shoot length and in fresh and dry weight of root and shoot and reduction in the root-knot index over the control were attained. In overall performance, VP2 was 29.5% more effective than VP1, and about 30% more effective than the control (non-bacterised). The application of P. aeruginosa VP1 and P. aeruginosa VP2 controls the development of M. incognita in C. annuum, and hence they are recommended as efficient plant growth promotors and biocontrolling agents for raising healthy crop of C. annuum that can promote the growth of plants and reduce the nematode (M. incognita) population. Copyright © 2012 Society of Chemical Industry.

Implications of Climate Change for Children in Developing Countries

ERIC Educational Resources Information Center

Hanna, Rema; Oliva, Paulina

2016-01-01

Climate change may be particularly dangerous for children in developing countries. Even today, many developing countries experience a disproportionate share of extreme weather, and they are predicted to suffer disproportionately from the effects of climate change in the future. Moreover, developing countries often have limited social safety nets,…

Preparing Teachers to Support the Development of Climate Literate Students

NASA Astrophysics Data System (ADS)

Haddad, N.; Ledley, T. S.; Ellins, K. K.; Bardar, E. W.; Youngman, E.; Dunlap, C.; Lockwood, J.; Mote, A. S.; McNeal, K.; Libarkin, J. C.; Lynds, S. E.; Gold, A. U.

2014-12-01

The EarthLabs climate project includes curriculum development, teacher professional development, teacher leadership development, and research on student learning, all directed at increasing high school teachers' and students' understanding of the factors that shape our planet's climate. The project has developed four new modules which focus on climate literacy and which are part of the larger Web based EarthLabs collection of Earth science modules. Climate related themes highlighted in the new modules include the Earth system with its positive and negative feedback loops; the range of temporal and spatial scales at which climate, weather, and other Earth system processes occur; and the recurring question, "How do we know what we know about Earth's past and present climate?" which addresses proxy data and scientific instrumentation. EarthLabs climate modules use two central strategies to help students navigate the multiple challenges inherent in understanding climate science. The first is to actively engage students with the content by using a variety of learning modes, and by allowing students to pace themselves through interactive visualizations that address particularly challenging content. The second strategy, which is the focus of this presentation, is to support teachers in a subject area where few have substantive content knowledge or technical skills. Teachers who grasp the processes and interactions that give Earth its climate and the technical skills to engage with relevant data and visualizations are more likely to be successful in supporting students' understanding of climate's complexities. This presentation will briefly introduce the EarthLabs project and will describe the steps the project takes to prepare climate literate teachers, including Web based resources, teacher workshops, and the development of a cadre of teacher leaders who are prepared to continue leading the workshops after project funding ends.

Meloidogyne aberrans sp. nov. (Nematoda: Meloidogynidae), a new root-knot nematode parasitizing kiwifruit in China.

PubMed

Tao, Ye; Xu, Chunling; Yuan, Chunfen; Wang, Honghong; Lin, Borong; Zhuo, Kan; Liao, Jinling

2017-01-01

High infection rates of roots of wild kiwifruit (Actinidia chinensis Planch) and soil infestation by a root-knot nematode were found in Anshun, GuiZhou Province, China. Morphology, esterase phenotype and molecular analyses confirmed that this nematode was different from previously described root-knot nematodes. In this report, the species is described, illustrated and named Meloidogyne aberrans sp. nov. The new species has a unique combination of characters. A prominent posterior protuberance, round and faint perineal pattern and a medium-length stylet (13.6-15.5 μm) characterized the females. Second-stage juveniles (J2) were characterized by a smooth lip region with distinctly protruded medial lips and a depression in outline at the oral aperture, a relatively long stylet (15.9-16.8 μm), four incisures in the lateral field and a very short, even poorly defined, hyaline tail terminus (2.2-5.5 μm). More incisures (11-15) existed in the lateral field of males, and the stylet and spicules of males were 18.2-19.6 μm and 22.7-36.8 μm long respectively. Egg masses were typically produced within the roots of kiwifruit. The new species had a rare Est phenotype, S2. Phylogenetic trees inferred from SSU, LSU D2D3, ITS, and partial coxII-16S rRNA revealed that M. aberrans sp. nov. was within the Meloidogyne clade and was distinguished from all described root-knot nematodes. Moreover, from histopathological observations, M. aberrans sp. nov. induced the formation of multinucleate giant cells.

Personalized Video Feedback and Repeated Task Practice Improve Laparoscopic Knot-Tying Skills: Two Controlled Trials.

PubMed

Abbott, Eduardo F; Thompson, Whitney; Pandian, T K; Zendejas, Benjamin; Farley, David R; Cook, David A

2017-11-01

Compare the effect of personalized feedback (PF) vs. task demonstration (TD), both delivered via video, on laparoscopic knot-tying skills and perceived workload; and evaluate the effect of repeated practice. General surgery interns and research fellows completed four repetitions of a simulated laparoscopic knot-tying task at one-month intervals. Midway between repetitions, participants received via e-mail either a TD video (demonstration by an expert) or a PF video (video of their own performance with voiceover from a blinded senior surgeon). Each participant received at least one video per format, with sequence randomly assigned. Outcomes included performance scores and NASA Task Load Index (NASA-TLX) scores. To evaluate the effectiveness of repeated practice, scores from these trainees on a separate delayed retention test were compared against historical controls who did not have scheduled repetitions. Twenty-one trainees completed the randomized study. Mean change in performance scores was significantly greater for those receiving PF (difference = 23.1 of 150 [95% confidence interval (CI): 0, 46.2], P = .05). Perceived workload was also significantly reduced (difference = -3.0 of 20 [95% CI: -5.8, -0.3], P = .04). Compared with historical controls (N = 93), the 21 with scheduled repeated practice had higher scores on the laparoscopic knot-tying assessment two weeks after the final repetition (difference = 1.5 of 10 [95% CI: 0.2, 2.8], P = .02). Personalized video feedback improves trainees' procedural performance and perceived workload compared with a task demonstration video. Brief monthly practice sessions support skill acquisition and retention.

Optimizing the efficacy of Paecilomyces lilacinus (strain 251) for the control of root-knot nematodes.

PubMed

Kiewnick, S; Sikora, R A

2004-01-01

The egg pathogenic fungus Paecilomyces lilacinus (strain 251) is a biocontrol fungus with a potential range of activity to control the worldwide most important plant parasitic nematodes. This biological nematicide may be an useful tool in an integrated approach to control mainly sedentary nematodes. Greenhouse experiments were conducted with the root-knot nematodes Meloidogyne incognita and M. hapla on tomato. P. lilacinus, formulated as WG (BIOACT WG), was incorporated into soil inoculated with root-knot nematode eggs prior to transplanting the susceptible tomato cultivar "Hellfrucht". Furthermore, soil treatments were combined with seedling treatments 24 hours before transplanting and a soil drench 2 weeks after planting, respectively. Seedling and post planting treatment was also combined with a soil treatment at planting. All single or combination treatments tested decreased the gall index and the number of egg masses compared to the untreated control 12 weeks after planting. However, the combination of the seedling treatment with a pre- or at-planting application of P. lilacinus was necessary to achieve higher levels of control. Additional post plant drenching resulted in only a slight increase In efficacy. To the feasibility of this modified application system for the control of root-knot nematodes, a yield experiment was conducted with M. hapla and the susceptible cultivar "Gnom F1 Hybrid". It could be demonstrated that the above mentioned combination of pre-planting application plus the seedling and one post plant drench gave the best control and resulted in a significant fruit yield increase in concurrence with a decrease in number of galls per root.

Developing and Evaluating Workshop Frameworks to Improve Climate Literacy

NASA Astrophysics Data System (ADS)

Averyt, K.; Alvord, C.; Joyce, L. A.; Lukas, J.; Barsugli, J. J.; Owen, G.; Udall, B.

2009-12-01

A burgeoning need for climate information is rising from a variety of stakeholders. A new federal report encourages federal resource management efforts to consider climate in assessments-leaving agency scientists and resource managers searching for appropriate data and methodologies. At the other end of the spectrum, small-scale decision makers realize the need to develop scientifically-informed climate adaptation plans, but are unclear about what science is relevant. It is becoming necessary to improve the climate literacy across all sectors. However, past examples illustrate that climate science has been insufficiently communicated, resulting in perceptions that misinform decision-making and planning. Given the necessity to include climate science in planning on multiple scales, scientific educators must work with stakeholders to determine how best to improve climate literacy. Doing so will reduce uncertainty in the application of climate data in planning, and thus mitigate vulnerabilities to the impacts of climate change. Here, we present the design and assessment of two workshop frameworks intended to improve the climate literacy of two distinct entities with different climate information needs. This work represents initial steps by the Western Water Assessment, a NOAA- Regionally Integrated Sciences and Assessments (RISA) Program, towards the development of a suite of process-oriented frameworks geared toward improving the climate literacy of different users with distinct informational needs. Both workshops focused on water-related climate issues: the first (Dealing with Drought: Climate Change in Colorado) was geared toward an audience with minimal exposure to climate information; the second was for US Forest Service hydrologists and managers with technical backgrounds. In both cases, the workshop format included presentations of relevant climate science, introductions to varied climate tools and products, and a needs-and-gaps assessment. Evaluation of each

Development of a Climate Prediction Market

NASA Astrophysics Data System (ADS)

Roulston, M. S.

2017-12-01

Winton, a global investment firm, is planning to establish a prediction market for climate. This prediction market will allow participants to place bets on global climate up to several decades in the future. Winton is pursuing this endeavour as part of its philanthropy that funds scientific research and the communication of scientific ideas. The Winton Climate Prediction Market will be based in the U.K. It will be structured as an online gambling site subject to the regulation of the Gambling Commission. Unlike existing betting sites, the Climate Prediction Market will be subsidized: a central market maker will inject money into the market. This is in contrast to traditional bookmakers or betting exchanges who set odds in their favour or charge commissions to make a profit. The philosophy of a subsidized prediction market is that the party seeking information should fund the market, rather than the participants who provide the information. The initial market will allow bets to be placed on the atmospheric concentration of carbon dioxide and the global mean temperature anomaly. It will thus produce implied forecasts of carbon dioxide concentration as well as global temperatures. If the initial market is successful, additional markets could be added which target other climate variables, such as regional temperatures or sea-level rise. These markets could be sponsored by organizations that are interested in predictions of the specific climate variables. An online platform for the Climate Prediction Market has been developed and has been tested internally at Winton.

Assessment of regional climate change and development of climate adaptation decision aids in the Southwestern US

NASA Astrophysics Data System (ADS)

Darmenova, K.; Higgins, G.; Kiley, H.; Apling, D.

2010-12-01

Current General Circulation Models (GCMs) provide a valuable estimate of both natural and anthropogenic climate changes and variability on global scales. At the same time, future climate projections calculated with GCMs are not of sufficient spatial resolution to address regional needs. Many climate impact models require information at scales of 50 km or less, so dynamical downscaling is often used to estimate the smaller-scale information based on larger scale GCM output. To address current deficiencies in local planning and decision making with respect to regional climate change, our research is focused on performing a dynamical downscaling with the Weather Research and Forecasting (WRF) model and developing decision aids that translate the regional climate data into actionable information for users. Our methodology involves development of climatological indices of extreme weather and heating/cooling degree days based on WRF ensemble runs initialized with the NCEP-NCAR reanalysis and the European Center/Hamburg Model (ECHAM5). Results indicate that the downscale simulations provide the necessary detailed output required by state and local governments and the private sector to develop climate adaptation plans. In addition we evaluated the WRF performance in long-term climate simulations over the Southwestern US and validated against observational datasets.

Ab-interno scleral suture loop fixation with cow-hitch knot in posterior chamber intraocular lens decentration

PubMed Central

Can, Ertuğrul; Koçak, Nurullah; Yücel, Özlem Eşki; Gül, Adem; Öztürk, Hilal Eser; Sayın, Osman

2016-01-01

Aim of Study: To describe a simplified ab-interno cow-hitch suture fixation technique for repositioning decentered posterior chamber intraocular lens (PC IOL). Materials and Methods: Two cases are presented with the surgical correction of decentered and subluxated IOL. Ab-interno scleral suture fixation technique with hitch-cow knot in the eye was performed with a ciliary sulcus guide instrument and 1 year follow-up was completed. Results: Both of the patients had well centered lenses postoperatively. Corrected distant and near visual acuities of the patients were improved. There was no significant postoperative complication. In the follow-up period of 1 year, no evidence of suture erosion was found. Conclusions: Ab-interno scleral suture loop fixation with hitch-cow knot in the eye was effective in repositioning decentered or subluxated PC IOLs with excellent postoperative centered lenses and visual outcomes. PMID:27050346

Damage-associated responses of the host contribute to defence against cyst nematodes but not root-knot nematodes.

PubMed

Shah, Syed Jehangir; Anjam, Muhammad Shahzad; Mendy, Badou; Anwer, Muhammad Arslan; Habash, Samer S; Lozano-Torres, Jose L; Grundler, Florian M W; Siddique, Shahid

2017-12-16

When nematodes invade and subsequently migrate within plant roots, they generate cell wall fragments (in the form of oligogalacturonides; OGs) that can act as damage-associated molecular patterns and activate host defence responses. However, the molecular mechanisms mediating damage responses in plant-nematode interactions remain unexplored. Here, we characterized the role of a group of cell wall receptor proteins in Arabidopsis, designated as polygalacturonase-inhibiting proteins (PGIPs), during infection with the cyst nematode Heterodera schachtii and the root-knot nematode Meloidogyne incognita. PGIPs are encoded by a family of two genes in Arabidopsis, and are involved in the formation of active OG elicitors. Our results show that PGIP gene expression is strongly induced in response to cyst nematode invasion of roots. Analyses of loss-of-function mutants and overexpression lines revealed that PGIP1 expression attenuates infection of host roots by cyst nematodes, but not root-knot nematodes. The PGIP1-mediated attenuation of cyst nematode infection involves the activation of plant camalexin and indole-glucosinolate pathways. These combined results provide new insights into the molecular mechanisms underlying plant damage perception and response pathways during infection by cyst and root-knot nematodes, and establishes the function of PGIP in plant resistance to cyst nematodes. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Reversible arterial redistribution in a fetus with true umbilical cord knot: case report and review of literature.

PubMed

Navolan, Dan Bogdan; Sas, Ioan; Grigoraş, Dorin; Moldovan, Mihaela; Cîrlan, Casius; Angheloiu Rîcă, Daiana Elena; Levai, Codrina Mihaela

2015-01-01

Umbilical cord knot (UCK) affects around 1% of pregnancies and tightening of UCK is a very rare and highly unpredictable complication of pregnancy that can lead to fetal demise or neonatal death. The majority of authors agree that very little could be done to prevent fetal deaths in pregnancies with undiagnosed tight UCK. We herein report the case of a 39-year-old, gravidity five, parity three, pregnant woman at 40 weeks and five days age of pregnancy, whose pregnancy evolved without complications and who was admitted to hospital for the management of the birth. Although the last ultrasound examination before birth showed a reversible arterial redistribution in the fetus dependent on the postural status of the pregnant women and other factors associated with umbilical cord knot were present, the diagnosis was missed because of the factors' non-specificity. After a spontaneous labor without complications a dead male fetus, weight 3300 g, without heartbeat, Apgar score 0 was delivered. Macroscopic and microscopic findings confirmed that the cause of neonatal death was asphyxia caused by a tight UCK. The aim of our paper is to present the dramatic outcome of a pregnancy with a fetus with a tight umbilical cord knot (UCK), to bring to attention the signs that suggested the diagnosis, and to review the literature on this subject.

Developing tools and strategies for communicating climate change

NASA Astrophysics Data System (ADS)

Bader, D.; Yam, E. M.; Perkins, L.

2011-12-01

Research indicates that the public views zoos and aquariums as reliable and trusted sources for information on conservation. Additionally, visiting zoos and aquariums helps people reconsider their connections to conservation issues and solutions. The Aquarium of the Pacific, an AZA-accredited institution that serves the most ethnically diverse population of all aquariums in the nation, is using exhibit space, technology, public programming, and staff professional development to present a model for how aquariums can promote climate literacy. Our newest galleries and programs are designed to immerse our visitors in experiences that connect our live animal collection to larger themes on ocean change. The Aquarium is supporting our new programming with a multifaceted staff professional development that exposes our interpretive staff to current climate science and researchers as well as current social science on public perception of climate science. Our staff also leads workshops for scientists; these sessions allow us to examine learning theory and develop tools to communicate science and controversial subjects effectively. Through our partnerships in the science, social science, and informal science education communities, we are working to innovate and develop best practices in climate communication.

Disciplinary Knots and Learning Problems in Waves Physics

NASA Astrophysics Data System (ADS)

Di Renzone, Simone; Frati, Serena; Montalbano, Vera

An investigation on student understanding of waves is performed during an optional laboratory realized in informal extracurricular way with few, interested and talented pupils. The background and smart intuitions of students rendered the learning path very dynamic and ambitious. The activities started by investigating the basic properties of waves by means of a Shive wave machine. In order to make quantitative observed phenomena, the students used a camcorder and series of measures were obtained from the captured images. By checking the resulting data, it arose some learning difficulties especially in activities related to the laboratory. This experience was the starting point for a further analysis on disciplinary knots and learning problems in the physics of waves in order to elaborate a teaching-learning proposal on this topic.

The Origin of the Iron-rich Knot in Tycho’s Supernova Remnant

NASA Astrophysics Data System (ADS)

Yamaguchi, Hiroya; Hughes, John P.; Badenes, Carles; Bravo, Eduardo; Seitenzahl, Ivo R.; Martínez-Rodríguez, Héctor; Park, Sangwook; Petre, Robert

2017-01-01

X-ray observations of supernova remnants (SNRs) allow us to investigate the chemical inhomogeneity of ejecta, offering unique insight into the nucleosynthesis in supernova explosions. Here we present detailed imaging and spectroscopic studies of the “Fe knot” located along the eastern rim of the Type Ia SNR Tycho (SN 1572) using Suzaku and Chandra long-exposure data. Surprisingly, the Suzaku spectrum of this knot shows no emission from Cr, Mn, or Ni, which is unusual for the Fe-rich regions in this SNR. Within the framework of the canonical delayed-detonation models for SN Ia, the observed mass ratios {M}{Cr}/{M}{Fe}< 0.023, {M}{Mn}/{M}{Fe}< 0.012, and {M}{Ni}/{M}{Fe}< 0.029 (at 90% confidence) can only be achieved for a peak temperature of (5.3-5.7) × {10}9 K and a neutron excess of ≲ 2.0× {10}-3. These constraints rule out the deep, dense core of a Chandrasekhar-mass white dwarf as the origin of the Fe knot and favor either incomplete Si burning or an α-rich freeze-out regime, probably close to the boundary. An explosive He burning regime is a possible alternative, although this hypothesis is in conflict with the main properties of this SNR.

Topological Vortex and Knotted Dissipative Optical 3D Solitons Generated by 2D Vortex Solitons

NASA Astrophysics Data System (ADS)

Veretenov, N. A.; Fedorov, S. V.; Rosanov, N. N.

2017-12-01

We predict a new class of three-dimensional (3D) topological dissipative optical one-component solitons in homogeneous laser media with fast saturable absorption. Their skeletons formed by vortex lines where the field vanishes are tangles, i.e., Nc knotted or unknotted, linked or unlinked closed lines and M unclosed lines that thread all the closed lines and end at the infinitely far soliton periphery. They are generated by embedding two-dimensional laser solitons or their complexes in 3D space after their rotation around an unclosed, infinite vortex line with topological charge M0 (Nc , M , and M0 are integers). With such structure propagation, the "hula-hoop" solitons form; their stability is confirmed numerically. For the solitons found, all vortex lines have unit topological charge: the number of closed lines Nc=1 and 2 (unknots, trefoils, and Solomon knots links); unclosed vortex lines are unknotted and unlinked, their number M =1 , 2, and 3.

Topological Vortex and Knotted Dissipative Optical 3D Solitons Generated by 2D Vortex Solitons.

PubMed

Veretenov, N A; Fedorov, S V; Rosanov, N N

2017-12-29

We predict a new class of three-dimensional (3D) topological dissipative optical one-component solitons in homogeneous laser media with fast saturable absorption. Their skeletons formed by vortex lines where the field vanishes are tangles, i.e., N_{c} knotted or unknotted, linked or unlinked closed lines and M unclosed lines that thread all the closed lines and end at the infinitely far soliton periphery. They are generated by embedding two-dimensional laser solitons or their complexes in 3D space after their rotation around an unclosed, infinite vortex line with topological charge M_{0} (N_{c}, M, and M_{0} are integers). With such structure propagation, the "hula-hoop" solitons form; their stability is confirmed numerically. For the solitons found, all vortex lines have unit topological charge: the number of closed lines N_{c}=1 and 2 (unknots, trefoils, and Solomon knots links); unclosed vortex lines are unknotted and unlinked, their number M=1, 2, and 3.

Development and nationwide scale-up of Climate Matters, a localized climate change education program delivered by TV weathercasters.

NASA Astrophysics Data System (ADS)

Cullen, H. M.; Maibach, E.

2016-12-01

Most Americans view climate change as a threat that is distant in space (i.e., not here), time (i.e., not now), and species (i.e., not us). TV weathercasters are ideally positioned to educate Americans about the current and projected impacts of climate change in their community: they have tremendous reach, are trusted sources of climate information, and are highly skilled science communicators. In 2009, we learned that many weathercasters were potentially interested in reporting on climate change, but few actually were, citing significant barriers including a lack of time to prepare and air stories, and lack of access to high quality content. To test the premise that TV weathercasters can be effective climate educators - if supported with high quality localized climate communication content - in 2010 George Mason University, Climate Central and WLTX-TV (Columbia, SC) developed and pilot-tested Climate Matters, a series of short on-air (and online) segments about the local impacts of climate change, delivered by the station's chief meteorologist. During the first year, more than a dozen stories aired. To formally evaluate Climate Matters, we conducted pre- and post-test surveys of local TV news viewers in Columbia. After one year, WLTX viewers had developed a more science-based understanding of climate change than viewers of other local news stations, confirming our premise that when TV weathercasters report on the local implications of climate change, their viewers learn. Through a series of expansions, including the addition of important new partners - AMS, NASA, NOAA & Yale University - Climate Matters has become a comprehensive nationwide climate communication resource program for American TV weathercasters. As of March 2016, a network of 313 local weathercasters nationwide (at 202 stations in 111 media markets) are participating in the program, receiving new content on a weekly basis. This presentation will review the theoretical basis of the program, detail

Anthropology is missing: on the World Development Report 2010: Development and Climate Change.

PubMed

Trostle, James

2010-07-01

When the World Bank publishes a report on climate change, the world takes notice. What are its diagnoses and treatments, and how present is anthropology in this analysis? The 2010 World Development Report on climate change provides few new diagnostic tools and no clear Bank policy revisions. It often fails to harmonize neoliberal development rhetoric with new climate-change imperatives. It nods to the importance of social context and risk perception yet refers primarily to behavioral economics and psychological constructs. Although anthropologists are documenting the local effects and human responses to larger-scale, climate-driven processes, our work is absent in the report. To play a role at global scale we would do well to learn more about concepts like nonlinearity and emergence, systems analysis, modeling, and disease dynamics. Our adroitness in developing metaphors and methods for crossing scale will make our efforts more visible and applicable.

Gene action analysis by inheritance and QTL mapping of resistance to root-knot nematodes in cotton.

USDA-ARS?s Scientific Manuscript database

Host-plant resistance is highly effective in controlling crop loss from nematode infection. In addition, molecular markers can be powerful tools for marker-assisted selection (MAS), where they reduce laborious greenhouse phenotype evaluation to identify root-knot nematode (RKN) Meloidogyne incognita...

The Circumstellar Medium of Cassiopeia A Inferred from the Outer Ejecta Knot Properties

NASA Technical Reports Server (NTRS)

Hwang, Una; Laming, J. Martin

2009-01-01

We investigate the effect of the circumstellar medium density profile on the X-ray emission from outer ejecta knots in the Cassiopeia A supernova remnant using the 1 Ms Chandra observation. The spectra of a number of radial series of ejecta knots at various positions around the remnant are analyzed using techniques similar to those devised in previous papers. We can obtain a reasonable match to our data for a circumstellar density profile proportional to r(sup -2) as would arise from the steady dense wind of a red supergiant, but the agreement is improved if we introduce a central cavity around the progenitor into our models. Such a profile might arise if the progenitor emitted a, fast tenuous stellar wind for a short period immediately prior to explosion. We review other lines of evidence supporting this conclusion. The spectra also indicate the widespread presence of Fe-enriched plasma that was presumably formed by complete Si burning during the explosion, possibly via alpha-rich freezeout. This component is typically associated with hotter and more highly ionized gas than the bulk of the O- and Si-rich ejecta.

Initial speed of knots in the plasma tail of C/2013 R1(Lovejoy)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yagi, Masafumi; Furusho, Reiko; Terai, Tsuyoshi

We report short-time variations in the plasma tail of C/2013 R1(Lovejoy). A series of short (2–3 minutes) exposure images with the 8.2 m Subaru telescope shows faint details of filaments and their motions over a 24 minute observing duration. We identified rapid movements of two knots in the plasma tail near the nucleus (∼3×10{sup 5} km). Their speeds are 20 and 25 km s{sup −1} along the tail and 3.8 and 2.2 km s{sup −1} across it, respectively. These measurements set a constraint on an acceleration model of plasma tail and knots as they set the initial speed just aftermore » their formation. We also found a rapid narrowing of the tail. After correcting the motion along the tail, the narrowing speed is estimated to be ∼8 km s{sup −1}. These rapid motions suggest the need for high time-resolution studies of comet plasma tails with a large telescope.« less

A quantitative comparison of Soil Development in four climatic regimes

USGS Publications Warehouse

Harden, J.W.; Taylor, E.M.

1983-01-01

A new quantitative Soil Development Index based on field data has been applied to chronosequences formed under different climatic regimes. The four soil chronosequences, developed primarily on sandy deposits, have some numeric age control and are located in xeric-inland (Merced, Calif.), xeric-coastal (Ventura, Calif.), aridic (Las Cruces, N. Mex.), and udic (Susquehanna Valley, Pa.) soil-moisture regimes. To quantify field properties, points are assigned for developmental increases in soil properties in comparison to the parent material. Currently ten soil-field properties are quantified and normalized for each horizon in a given chronosequence, including two new properties for carbonate-rich soils in addition to the eight properties previously defined. When individual properties or the combined indexes are plotted as a function of numeric age, rates of soil development can be compared in different climates. The results demonstrate that (1) the Soil Development Index can be applied to very different soil types, (2) many field properties develop systematically in different climatic regimes, (3) certain properties appear to have similar rates of development in different climates, and (4) the Profile Index that combines different field properties increases significantly with age and appears to develop at similar rates in different climates. The Soil Development Index can serve as a preliminary guide to soil age where other age control is lacking and can be used to correlate deposits of different geographical and climatic regions. ?? 1983.

Developing country finance in a post-2020 global climate agreement

NASA Astrophysics Data System (ADS)

Hannam, Phillip M.; Liao, Zhenliang; Davis, Steven J.; Oppenheimer, Michael

2015-11-01

A central task for negotiators of the post-2020 global climate agreement is to construct a finance regime that supports low-carbon development in developing economies. As power sector investments between developing countries grow, the climate finance regime should incentivize the decarbonization of these major sources of finance by integrating them as a complement to the commitments of developed nations. The emergence of the Asian Infrastructure Investment Bank, South-South Cooperation Fund and other nascent institutions reveal the fissures that exist in rules and norms surrounding international finance in the power sector. Structuring the climate agreement in Paris to credit qualified finance from the developing world could have several advantages, including: (1) encouraging low-carbon cooperation between developing countries; (2) incentivizing emerging investors to prefer low-carbon investments; and (3) enabling more cost-effective attainment of national and global climate objectives. Failure to coordinate on standards now could hinder low-carbon development in the decades to come.

Meloidogyne aberrans sp. nov. (Nematoda: Meloidogynidae), a new root-knot nematode parasitizing kiwifruit in China

PubMed Central

Yuan, Chunfen; Wang, Honghong; Lin, Borong; Zhuo, Kan; Liao, Jinling

2017-01-01

High infection rates of roots of wild kiwifruit (Actinidia chinensis Planch) and soil infestation by a root-knot nematode were found in Anshun, GuiZhou Province, China. Morphology, esterase phenotype and molecular analyses confirmed that this nematode was different from previously described root-knot nematodes. In this report, the species is described, illustrated and named Meloidogyne aberrans sp. nov. The new species has a unique combination of characters. A prominent posterior protuberance, round and faint perineal pattern and a medium-length stylet (13.6–15.5 μm) characterized the females. Second-stage juveniles (J2) were characterized by a smooth lip region with distinctly protruded medial lips and a depression in outline at the oral aperture, a relatively long stylet (15.9–16.8 μm), four incisures in the lateral field and a very short, even poorly defined, hyaline tail terminus (2.2–5.5 μm). More incisures (11–15) existed in the lateral field of males, and the stylet and spicules of males were 18.2–19.6 μm and 22.7–36.8 μm long respectively. Egg masses were typically produced within the roots of kiwifruit. The new species had a rare Est phenotype, S2. Phylogenetic trees inferred from SSU, LSU D2D3, ITS, and partial coxII-16S rRNA revealed that M. aberrans sp. nov. was within the Meloidogyne clade and was distinguished from all described root-knot nematodes. Moreover, from histopathological observations, M. aberrans sp. nov. induced the formation of multinucleate giant cells. PMID:28854186

Spline curve matching with sparse knot sets: applications to deformable shape detection and recognition

Treesearch

Sang-Mook Lee; A. Lynn Abbott; Neil A. Clark; Philip A. Araman

2003-01-01

Splines can be used to approximate noisy data with a few control points. This paper presents a new curve matching method for deformable shapes using two-dimensional splines. In contrast to the residual error criterion, which is based on relative locations of corresponding knot points such that is reliable primarily for dense point sets, we use deformation energy of...

Chapter 7: Developing climate-informed state-and-transition models

Treesearch

Miles A. Hemstrom; Jessica E. Halofsky; David R. Conklin; Joshua S. Halofsky; Dominique Bachelet; Becky K. Kerns

2014-01-01

Land managers and others need ways to understand the potential effects of climate change on local vegetation types and how management activities might be impacted by climate change. To date, climate change impact models have not included localized vegetation communities or the integrated effects of vegetation development dynamics, natural disturbances, and management...

PROPER MOTIONS OF THE OUTER KNOTS OF THE HH 80/81/80N RADIO-JET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masqué, Josep M.; Rodriguez, Luis F.; Carrasco-González, Carlos

2015-11-20

The radio-knots of the Herbig–Haro (HH) 80/81/80N jet extend from the HH 80 object to the recently discovered Source 34 and has a total projected jet size of 10.3 pc, constituting the largest collimated radio-jet system known so far. It is powered by the bright infrared source IRAS 18162−2048 associated with a massive young stellar object. We report 6 cm JVLA observations that, compared with previous 6 cm VLA observations carried out in 1989, allow us to derive proper motions of the HH 80, HH 81, and HH 80N radio knots located about 2.5 pc away in projection from themore » powering source. For the first time, we measure proper motions of the optically obscured HH 80N object providing evidence that this knot, along with HH 81 and HH 80 are associated with the same radio-jet. We also confirm the presence of Source 34, located further north of HH 80N, previously proposed to belong to the jet.We derived that the tangential velocity of HH 80N is 260 km s{sup −1} and has a direction in agreement with the expected direction of a ballistic precessing jet. The HH 80 and HH 81 objects have tangential velocities of 350 and 220 km s{sup −1}, respectively, but their directions are somewhat deviated from the expected jet path. The velocities of the HH objects studied in this work are significantly lower than those derived for the radio knots of the jet close to the powering source (600–1400 km s{sup −1}) suggesting that the jet is slowing down due to a strong interaction with the ambient medium. As a result, since HH 80 and HH 81 are located near the edge of the cloud, the inhomogeneous and low density medium may contribute to skew the direction of their determined proper motions. The HH 80 and HH 80N emission at 6 cm is, at least in part, probably synchrotron radiation produced by relativistic electrons in a magnetic field of 1 mG. If these electrons are accelerated in a reverse adiabatic shock, we estimate a jet total density of ≲1000 cm{sup −3}. All of these

Economic design in a long-distance migrating molluscivore: how fast-fuelling red knots in Bohai Bay, China, get away with small gizzards.

PubMed

Yang, Hong-Yan; Chen, Bing; Ma, Zhi-Jun; Hua, Ning; van Gils, Jan A; Zhang, Zheng-Wang; Piersma, Theunis

2013-10-01

We carried out an observational and experimental study to decipher how resource characteristics, in interaction with the predator's phenotype, constrain a fitness-determining performance measure, i.e. refuelling in a migrant bird. Two subspecies of red knot (Calidris canutus rogersi and C. c. piersmai) use northern Bohai Bay, Yellow Sea, China, for the final prebreeding stopover, during their 10,000-15,000 km long migrations between wintering and breeding areas. Here, they feed on small bivalves, especially 2-7 mm long Potamocorbula laevis. With an average stay of 29 days, and the need to store 80 g of fat for the onward flights to high-Arctic breeding grounds, red knots need to refuel fast. Using existing knowledge, we expected them to achieve this on the basis of (1) prey with high flesh to shell mass ratios, (2) large gizzards to crush the ingested molluscs, or (3) a combination of the two. Rejecting all three predictions, we found that red knots staging in Bohai Bay had the smallest gizzards on record (4.9 ± 0.8 g, mean ± s.e.m., N = 27), and also found that prey quality of P. laevis is much lower than predicted for the measured gizzard size (i.e. 1.3 rather than the predicted 4.5 kJ g(-1) dry shell mass, DM(shell)). The estimated handling time of P. laevis (0.2 s) is much shorter than the observed time between two prey ingestions (0.7 s), indicating that prey handling time is no constraint. Based on field observations of dropping rates and on indoor digestion trails, the shell processing rate was estimated at 3.9 mg DM(shell) s(-1), i.e. three times higher the rate previously predicted for red knots eating as fast as they can with the measured gizzard size. This is explained by the small and easily crushed P. laevis enabling high processing rates. As P. laevis also occurred in high densities, the metabolizable energy intake rate of red knots with small gizzards at 5 J s(-1) was as high as at northward staging sites elsewhere in the world. Currently

Effect of simultaneous drought stress and root-knot nematode infection on cotton yield and fiber quality

USDA-ARS?s Scientific Manuscript database

Both drought stress and root-knot nematode (Meloidogyne incognita) infection can reduce cotton yield, and drought can affect fiber quality, but it not known what effect the nematodes have on fiber quality. To determine whether nematode parasitism affects fiber quality and whether the combined effec...

Impact of grapevine (Vitis vinifera) varieties on reproduction of the northern root-knot nematode (Meloidogyne hapla)

USDA-ARS?s Scientific Manuscript database

Plant-parasitic nematodes are microscopic soil worms that attack the roots of grape plants and cause yield loss. One of the most commonly encountered plant-parasitic nematodes in eastern Washington Vitis vinifera vineyards is Meloidogyne hapla, the northern root-knot nematode. The selection of plant...

Exploring the Climate Literacy Development Utilizing a Learning Progressions Approach

NASA Astrophysics Data System (ADS)

Drewes, A.; Breslyn, W.; McGinnis, J. R.; Hestness, E.; Mouza, C.

2017-12-01

Climate change encompasses a broad and complex set of concepts that is often challenging for students and educators. Using a learning progressions framework, in this exploratory study we report our efforts to identify, describe, and organize the development of learners' understanding of climate change in an empirically supported learning progression (LP). The learning progression framework is a well suited analytical tool for investigating how student thinking develops over time (Duschl et al., 2007). Our primary research question is "How do learners progress over time from an initial to a more sophisticated understanding of climate change?"We followed a development process that involved drafting a hypothetical learning progression based on the science education research literature, consensus documents such as the Next Generation Science Standards and the Atlas of Science Literacy. Additionally, we conducted expert reviews with both climate scientists and educational researchers on the content and pedagogical expectations. Data are then collected from learners, which are used to modify the hypothetical learning progression based on how well it describes actual student learning. In this current analysis, we present findings from written assessments (N=294) and in-depth interviews (n=27) with middle school students in which we examine their understanding of the role of human activity, the greenhouse effect as the mechanism of climate change, local and global impacts, and strategies for the adaptation and mitigation of climate change. The culmination of our research is a proposed, empirically supported LP for climate change. Our LP is framed by consideration of four primary constructs: Human Activity, Mechanism, Impacts, and Mitigation and Adaptation. The conditional LP provides a solid foundation for continued research as well as providing urgently needed guidance to the education community on climate change education (for curriculum, instruction, and assessment

A knotted1-like homeobox protein regulates abscission in tomato by modulating the auxin pathway

USDA-ARS?s Scientific Manuscript database

KD1, a gene encoding a KNOTTED1-LIKE HOMEOBOX transcription factor is known to be involved, in tomato, in ontogeny of the compound leaf. KD1 is also highly expressed in both leaf and flower abscission zones. Reducing abundance of transcripts of this gene in tomato, using both virus induced gene sile...

Adapting the CROPGRO cotton model to simulate cotton biomass and yield under southern root-knot nematode parasitism

USDA-ARS?s Scientific Manuscript database

Cotton (Gossypium hirsutum L.) yield losses by southern root-knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood] (RKN) are usually estimated after significant damage has been caused. However, estimation of potential yield reduction before planting is possible by using crop simulation mod...

Towards a threshold climate for emergency lower respiratory hospital admissions.

PubMed

Islam, Muhammad Saiful; Chaussalet, Thierry J; Koizumi, Naoru

2017-02-01

Identification of 'cut-points' or thresholds of climate factors would play a crucial role in alerting risks of climate change and providing guidance to policymakers. This study investigated a 'Climate Threshold' for emergency hospital admissions of chronic lower respiratory diseases by using a distributed lag non-linear model (DLNM). We analysed a unique longitudinal dataset (10 years, 2000-2009) on emergency hospital admissions, climate, and pollution factors for the Greater London. Our study extends existing work on this topic by considering non-linearity, lag effects between climate factors and disease exposure within the DLNM model considering B-spline as smoothing technique. The final model also considered natural cubic splines of time since exposure and 'day of the week' as confounding factors. The results of DLNM indicated a significant improvement in model fitting compared to a typical GLM model. The final model identified the thresholds of several climate factors including: high temperature (≥27°C), low relative humidity (≤ 40%), high Pm10 level (≥70-µg/m 3 ), low wind speed (≤ 2 knots) and high rainfall (≥30mm). Beyond the threshold values, a significantly higher number of emergency admissions due to lower respiratory problems would be expected within the following 2-3 days after the climate shift in the Greater London. The approach will be useful to initiate 'region and disease specific' climate mitigation plans. It will help identify spatial hot spots and the most sensitive areas and population due to climate change, and will eventually lead towards a diversified health warning system tailored to specific climate zones and populations. Copyright © 2016 Elsevier Inc. All rights reserved.

Biocontrol Efficacy of Formulated Pseudomonas chlororaphis O6 against Plant Diseases and Root-Knot Nematodes

PubMed Central

Nam, Hyo Song; Anderson, Anne J.; Kim, Young Cheol

2018-01-01

Commercial biocontrol of microbial plant diseases and plant pests, such as nematodes, requires field-effective formulations. The isolate Pseudomonas chlororaphis O6 is a Gram-negative bacterium that controls microbial plant pathogens both directly and indirectly. This bacterium also has nematocidal activity. In this study, we report on the efficacy of a wettable powder-type formulation of P. chlororaphis O6. Culturable bacteria in the formulated product were retained at above 1 × 108 colony forming units/g after storage of the powder at 25 °C for six months. Foliar application of the diluted formulated product controlled leaf blight and gray mold in tomato. The product also displayed preventative and curative controls for root-knot nematode (Meloidogyne spp.) in tomato. Under laboratory conditions and for commercially grown melon, the control was at levels comparable to that of a standard commercial chemical nematicide. The results indicated that the wettable powder formulation product of P. chlororaphis O6 can be used for control of plant microbial pathogens and root-knot nematodes. PMID:29887780

A direct method to solve optimal knots of B-spline curves: An application for non-uniform B-spline curves fitting.

PubMed

Dung, Van Than; Tjahjowidodo, Tegoeh

2017-01-01

B-spline functions are widely used in many industrial applications such as computer graphic representations, computer aided design, computer aided manufacturing, computer numerical control, etc. Recently, there exist some demands, e.g. in reverse engineering (RE) area, to employ B-spline curves for non-trivial cases that include curves with discontinuous points, cusps or turning points from the sampled data. The most challenging task in these cases is in the identification of the number of knots and their respective locations in non-uniform space in the most efficient computational cost. This paper presents a new strategy for fitting any forms of curve by B-spline functions via local algorithm. A new two-step method for fast knot calculation is proposed. In the first step, the data is split using a bisecting method with predetermined allowable error to obtain coarse knots. Secondly, the knots are optimized, for both locations and continuity levels, by employing a non-linear least squares technique. The B-spline function is, therefore, obtained by solving the ordinary least squares problem. The performance of the proposed method is validated by using various numerical experimental data, with and without simulated noise, which were generated by a B-spline function and deterministic parametric functions. This paper also discusses the benchmarking of the proposed method to the existing methods in literature. The proposed method is shown to be able to reconstruct B-spline functions from sampled data within acceptable tolerance. It is also shown that, the proposed method can be applied for fitting any types of curves ranging from smooth ones to discontinuous ones. In addition, the method does not require excessive computational cost, which allows it to be used in automatic reverse engineering applications.

Effects of temperature on the life-history traits of Sancassania (Caloglyphus) berlesei (Acari: Astigmatina: Acaridae) feeding on root-knot nematodes, Meloidogyne spp. (Nematoda: Meloidogynidae).

PubMed

Abou El-Atta, Doaa Abd El-Maksoud; Ghazy, Noureldin Abuelfadl; Osman, Mohamed Ali

2014-11-01

Sancassania (Caloglyphus) berlesei (Michael) is a cosmopolitan and free-living mite that inhabits soil as well as laboratory colonies of insects and fungi and may have a role as a biocontrol agent of nematodes. In this study, we investigated the effects of temperature on the development, reproduction, and food consumption of S. berlesei fed egg masses of root-knot nematodes, Meloidogyne spp., an important group of agricultural pests. Mites were reared at 20, 25 or 30 °C in the dark. The mites could feed on the nematode egg masses, and their developmental time decreased at higher temperatures. Time from the egg to adult was similar in females and males reared at the same temperature. Adult females lived longer than males at 25 °C, but not at 20 or 30 °C. Generally, females showed a higher rate of food consumption than males. Females laid the largest number of eggs at 20 and 25 °C (199.7 and 189.8 eggs/female, respectively), but the intrinsic rate of natural increase was highest at 30 °C (r m = 0.29). In comparing our data with previous reports, we noted that S. berlesei that fed on egg masses of root-knot nematodes showed a longer developmental time and a lower reproductive rate than Sancassania mites that fed on other diets. Nonetheless, the relatively high value of r m (e.g., at 25 and 30 °C) suggests that this mite may have certain advantages as a biocontrol agent of root-knot nematodes.

Development of regional climate scenarios in the Netherlands - involvement of users

NASA Astrophysics Data System (ADS)

Bessembinder, Janette; Overbeek, Bernadet

2013-04-01

Climate scenarios are consistent and plausible pictures of possible future climates. They are intended for use in studies exploring the impacts of climate change, and to formulate possible adaptation strategies. To ensure that the developed climate scenarios are relevant to the intended users, interaction with the users is needed. As part of the research programmes "Climate changes Spatial Planning" and "Knowledge for Climate" several projects on climate services, tailoring of climate information and communication were conducted. Some of the important lessons learned about user interaction are: *) To be able to deliver relevant climate information in the right format, proper knowledge is required on who will be using the climate information and data, how it will be used and why they use it; *) Users' requirements can be very diverse and requirements may change over time. Therefore, sustained (personal) contact with users is required; *) Organising meetings with climate researchers and users of climate information together, and working together in projects results in mutual understanding on the requirements of users and the limitations to deliver certain types of climate information, which facilitates the communication and results in more widely accepted products; *) Information and communication should be adapted to the type of users (e.g. impact researchers or policy makers) and to the type of problem (unstructured problems require much more contact with the users). In 2001 KNMI developed climate scenarios for the National Commission on Water management in the 21st century (WB21 scenarios). In 2006 these were replaced by a the KNMI'06 scenarios, intended for a broader group of users. The above lessons are now taken into account during the development of the next generation of climate scenarios for the Netherlands, expected at the end of 2013, after the publication of the IPCC WG1 report: *) users' requirements are taken into account explicitly in the whole process

Using Organization Development To Improve School Climate. Report No. 17.

ERIC Educational Resources Information Center

Gottfredson, Gary D.; Gottfredson, Denise C.

This paper presents and illustrates some principles for organizational development approaches to improving school climate. It discusses a specific structure for facilitating school improvement entitled Program Development Evaluation, and it illustrates the use of school climate assessments for school diagnosis and the evaluation of improvement…

Average size of random polygons with fixed knot topology.

PubMed

Matsuda, Hiroshi; Yao, Akihisa; Tsukahara, Hiroshi; Deguchi, Tetsuo; Furuta, Ko; Inami, Takeo

2003-07-01

We have evaluated by numerical simulation the average size R(K) of random polygons of fixed knot topology K=,3(1),3(1) musical sharp 4(1), and we have confirmed the scaling law R(2)(K) approximately N(2nu(K)) for the number N of polygonal nodes in a wide range; N=100-2200. The best fit gives 2nu(K) approximately 1.11-1.16 with good fitting curves in the whole range of N. The estimate of 2nu(K) is consistent with the exponent of self-avoiding polygons. In a limited range of N (N greater, similar 600), however, we have another fit with 2nu(K) approximately 1.01-1.07, which is close to the exponent of random polygons.

Readying health services for climate change: a policy framework for regional development.

PubMed

Bell, Erica

2011-05-01

Climate change presents the biggest threat to human health in the 21st century. However, many public health leaders feel ill equipped to face the challenges of climate change and have been unable to make climate change a priority in service development. I explore how to achieve a regionally responsive whole-of-systems approach to climate change in the key operational areas of a health service: service governance and culture, service delivery, workforce development, asset management, and financing. The relative neglect of implementation science means that policymakers need to be proactive about sourcing and developing models and processes to make health services ready for climate change. Health research funding agencies should urgently prioritize applied, regionally responsive health services research for a future of climate change.

Readying Health Services for Climate Change: A Policy Framework for Regional Development

PubMed Central

2011-01-01

Climate change presents the biggest threat to human health in the 21st century. However, many public health leaders feel ill equipped to face the challenges of climate change and have been unable to make climate change a priority in service development. I explore how to achieve a regionally responsive whole-of-systems approach to climate change in the key operational areas of a health service: service governance and culture, service delivery, workforce development, asset management, and financing. The relative neglect of implementation science means that policymakers need to be proactive about sourcing and developing models and processes to make health services ready for climate change. Health research funding agencies should urgently prioritize applied, regionally responsive health services research for a future of climate change. PMID:21421953

Investigating Climate Compatible Development Outcomes and their Implications for Distributive Justice: Evidence from Malawi

NASA Astrophysics Data System (ADS)

Wood, Benjamin T.; Quinn, Claire H.; Stringer, Lindsay C.; Dougill, Andrew J.

2017-09-01

Governments and donors are investing in climate compatible development in order to reduce climate and development vulnerabilities. However, the rate at which climate compatible development is being operationalised has outpaced academic enquiry into the concept. Interventions aiming to achieve climate compatible development "wins" (for development, mitigation, adaptation) can also create negative side-effects. Moreover, benefits and negative side-effects may differ across time and space and have diverse consequences for individuals and groups. Assessments of the full range of outcomes created by climate compatible development projects and their implications for distributive justice are scarce. This article develops a framework using a systematic literature review that enables holistic climate compatible development outcome evaluation over seven parameters identified. Thereafter, we explore the outcomes of two donor-funded projects that pursue climate compatible development triple-wins in Malawi using this framework. Household surveys, semi-structured interviews and documentary material are analysed. Results reveal that uneven outcomes are experienced between stakeholder groups and change over time. Although climate compatible development triple-wins can be achieved through projects, they do not represent the full range of outcomes. Ecosystem—and community-based activities are becoming popularised as approaches for achieving climate compatible development goals. However, findings suggest that a strengthened evidence base is required to ensure that these approaches are able to meet climate compatible development goals and further distributive justice.

Developing a National Climate Indicators System to Track Climate Changes, Impacts, Vulnerabilities, and Preparedness

NASA Astrophysics Data System (ADS)

Kenney, M. A.; Janetos, A. C.; Arndt, D.; Chen, R. S.; Pouyat, R.; Anderson, S. M.

2013-12-01

The National Climate Assessment (NCA) is being conducted under the auspices of the U.S. Global Change Research Program (USGCRP), pursuant to the Global Change Research Act of 1990, Section 106, which requires a report to Congress every 4 years. Part of the vision, which is now under development, for the sustained National Climate Assessment (NCA) process is a system of physical, ecological, and societal indicators that communicate key aspects of the physical climate, climate impacts, vulnerabilities, and preparedness for the purpose of informing both decision makers and the public with scientifically valid information that is useful to inform decision-making processes such as the development and implementation of climate adaptation strategies in a particular sector or region. These indicators will be tracked as a part of ongoing assessment activities, with adjustments as necessary to adapt to changing conditions and understanding. The indicators will be reviewed and updated so that the system adapts to new information. The NCA indicator system is not intended to serve as a vehicle for documenting rigorous cause and effect relationships. It is reasonable, however, for it to serve as a guide to those factors that affect the evolution of variability and change in the climate system, the resources and sectors of concern that are affected by it, and how society chooses to respond. Different components of the end-to-end climate issue serve as categories within which to organize an end-to-end system of indicators: Greenhouse Gas Emissions and Sinks, Atmospheric Composition, Physical Climate Variability and Change, Sectors and Resources of Concern, and Adaptation and Mitigation Responses. This framing has several advantages. It can be used to identify the different components of the end-to-end climate issue that both decision-makers and researchers are interested in. It is independent of scale, and therefore allows the indicators themselves to be described at spatial

Comparing root knot nematode (Meloidogyne spp.) effects on tomato (Solanum lycopersicum) and grapevine (Vitis spp.) metabolic profiles

USDA-ARS?s Scientific Manuscript database

Root knot nematodes (Meloidogyne spp., RKN) can negatively impact both herbaceous annual and woody perennial hosts. RKN infestations also may increase plant host susceptibility to other stresses such as those imposed by water deficits or various diseases. However, little is known about direct or ind...

A Professional Development Climate Course for Sustainable Agriculture in Australia

ERIC Educational Resources Information Center

George, David; Clewett, Jeff; Birch, Colin; Wright, Anthony; Allen, Wendy

2009-01-01

There are few professional development courses in Australia for the rural sector concerned with climate variability, climate change and sustainable agriculture. The lack of educators with a sound technical background in climate science and its applications in agriculture prevents the delivery of courses either stand-alone or embedded in other…

eSACP - a new Nordic initiative towards developing statistical climate services

NASA Astrophysics Data System (ADS)

Thorarinsdottir, Thordis; Thejll, Peter; Drews, Martin; Guttorp, Peter; Venälainen, Ari; Uotila, Petteri; Benestad, Rasmus; Mesquita, Michel d. S.; Madsen, Henrik; Fox Maule, Cathrine

2015-04-01

The Nordic research council NordForsk has recently announced its support for a new 3-year research initiative on "statistical analysis of climate projections" (eSACP). eSACP will focus on developing e-science tools and services based on statistical analysis of climate projections for the purpose of helping decision-makers and planners in the face of expected future challenges in regional climate change. The motivation behind the project is the growing recognition in our society that forecasts of future climate change is associated with various sources of uncertainty, and that any long-term planning and decision-making dependent on a changing climate must account for this. At the same time there is an obvious gap between scientists from different fields and between practitioners in terms of understanding how climate information relates to different parts of the "uncertainty cascade". In eSACP we will develop generic e-science tools and statistical climate services to facilitate the use of climate projections by decision-makers and scientists from all fields for climate impact analyses and for the development of robust adaptation strategies, which properly (in a statistical sense) account for the inherent uncertainty. The new tool will be publically available and include functionality to utilize the extensive and dynamically growing repositories of data and use state-of-the-art statistical techniques to quantify the uncertainty and innovative approaches to visualize the results. Such a tool will not only be valuable for future assessments and underpin the development of dedicated climate services, but will also assist the scientific community in making more clearly its case on the consequences of our changing climate to policy makers and the general public. The eSACP project is led by Thordis Thorarinsdottir, Norwegian Computing Center, and also includes the Finnish Meteorological Institute, the Norwegian Meteorological Institute, the Technical University of Denmark

The impacts of climate change on poverty in 2030, and the potential from rapid, inclusive and climate-informed development

NASA Astrophysics Data System (ADS)

Rozenberg, J.; Hallegatte, S.

2016-12-01

There is a consensus on the fact that poor people are more vulnerable to climate change than the rest of the population, but, until recently, few quantified estimates had been proposed and few frameworks existed to design policies for addressing the issue. In this paper, we analyze the impacts of climate change on poverty using micro-simulation approaches. We start from household surveys that describe the current distribution of income and occupations, we project these households into the future and we look at the impacts of climate change on people's income. To project households into the future, we explore a large range of assumptions on future demographic changes (including on education), technological changes, and socio-economic trends (including redistribution policies). This approach allows us to identify the main combination of factors that lead to fast poverty reduction, and the ones that lead to high climate change impacts on the poor. Identifying these factors is critical for designing efficient policies to protect the poorest from climate change impacts and making economic growth more inclusive. Conclusions are twofold. First, by 2030 climate change can have a large impact on poverty, with between 3 and 122 million more people in poverty, but climate change remains a secondary driver of poverty trends within this time horizon. Climate change impacts do not only affect the poorest: in 2030, the bottom 40 percent lose more than 4 percent of income in many countries. The regional hotspots are Sub-Saharan Africa and - to a lesser extent - India and the rest of South Asia. The most important channel through which climate change increases poverty is through agricultural income and food prices. Second, by 2030 and in the absence of surprises on climate impacts, inclusive climate-informed development can prevent most of (but not all) the impacts on poverty. In a scenario with rapid, inclusive and climate-proof development, climate change impact on poverty is

Economic development and declining vulnerability to climate-related disasters in China

NASA Astrophysics Data System (ADS)

Wu, Jidong; Han, Guoyi; Zhou, Hongjian; Li, Ning

2018-03-01

Exposure and vulnerability are the main contributing factors of growing impact from climate-related disasters globally. Understanding the spatiotemporal dynamic patterns of vulnerability is important for designing effective disaster risk mitigation and adaptation measures. At national scale, most cross-country studies have suggested that economic vulnerability to disasters decreases as income increases, especially for developing countries. Research covering sub-national climate-related natural disasters is indispensable to obtaining a comprehensive understanding of the effect of regional economic growth on vulnerability reduction. Taking China as a case, this subnational scale study shows that economic development is correlated with the significant reduction in human fatalities but increase in direct economic losses (DELs) from climate-related disasters since 1949. The long-term trend in climate-related disaster vulnerability, reflected by mortality (1978-2015) and DELs (1990-2015) as a share of the total population and Gross Domestic Product, has seen significant decline among all economic regions in China. While notable differences remain among its West, Central and East economic regions, the temporal vulnerability change has been converging. The study further demonstrated that economic development level is correlated with human and economic vulnerability to climate-related disasters, and this vulnerability decreased with the increase of per-capita income. This study suggested that economic development can have nuanced effects on overall human and economic vulnerability to climate-related disasters. We argue that climate change science needs to acknowledge and examine the different pathways of vulnerability effects related to economic development.

A biomechanical comparison of 2 technical variations of double-row rotator cuff fixation: the importance of medial row knots.

PubMed

Busfield, Benjamin T; Glousman, Ronald E; McGarry, Michelle H; Tibone, James E; Lee, Thay Q

2008-05-01

Previous studies have shown comparable biomechanical properties of double-row fixation versus double-row fixation with a knotless lateral row. SutureBridge is a construct that secures the cuff with medial row mattress suture anchors and knotless lateral row fixation of the medial suture ends. Recent completely knotless constructs may lead to lesser clinical outcomes if the construct properties are compromised from lack of suture knots. A completely knotless construct without medial row knots will compromise the biomechanical properties in both cyclic and failure-testing parameters. Controlled laboratory study. Six matched pairs of cadaveric shoulders were randomized to 2 groups of double row fixation with SutureBridge: group 1 with medial row knots, and group 2 without medial row knots. The specimens were placed in a materials test system at 30 degrees of abduction. Cyclic testing to 180 N at 1 mm/sec for 30 cycles was performed, followed by tensile testing to failure at 1 mm/sec. Data included cyclic and failure data from the materials test system and gap data using a video digitizing system. All data from paired specimens were compared using paired Student t tests. Group 1 had a statistically significant difference (P < .05) for gap formation for the 1st (3.47 vs 5.05 mm) and 30th cycle (4.22 vs 8.10 mm) and at yield load (5.2 vs 9.1 mm). In addition, there was a greater energy absorbed (2805 vs 1648 N-mm), yield load (233 vs 183.1 N), and ultimate load (352.9 vs 253.9 N) for group 1. The mode of failure for the majority (4/6) of group 2 was lateral row failure, whereas all group 1 specimens failed at the clamp. Although lateral row knotless fixation has been shown not to sacrifice structural integrity of this construct, the addition of a knotless medial row compromises the construct leading to greater gapping and failure at lower loads. This may raise concerns regarding recently marketed completely knotless double row constructs.

Unexpected complication after cystometry in the hypocompliant urinary bladder: formation of a knot in the double lumen urethral catheter--a case report.

PubMed

Ayyildiz, Ali; Huri, Emre; Nuhoğlu, Bariş; Germiyanoğlu, Cankon

2006-01-01

Urodynamic evaluation is frequently used in the follow-up of the treatment and diagnosis of incontinence, which develops in connection with a neurogenic or non-neurogenic reason. There is no identified serious complication during or after urodynamic evaluation, present in the literature up to date. Hematuria, due to the urethral catheter, the development of oedema in the urinary bladder wall and the development of urinary bladder spasm as a result of catheter irritation, are some of the complications, which may occur. In this paper, twist and knot formation in the double lumen urethral catheter after cystometry of a patient with a hypocompliant urinary bladder, has been presented.

Knots as an incongruent product feature: a demonstration of the potential for character-marked hardwood furniture

Treesearch

M.S. Bumgardner; R.J. Bush; C.D. West; C.D. West

2001-01-01

Increased use of character-marks, or naturally occurring features of wood such as knots, in wood household furniture has received attention recently as a means for U.S. furniture manufacturers to make more efficient use of forest resources. However, little information exists concerning furniture retailers' perceptions of character-marked wood. Propositions that...

Greenhouse Development Rights. An approach to the global climate regime that takes climate protection seriously while also preserving the right to human development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Athanasiou, T.; Kartha, S.; Baer, P.

2006-11-15

This brief paper introduces a new approach to the global climate regime, one designed to recognize the urgency of the climate crisis, while at the same time embracing the fundamental right to human development. This 'Greenhouse Development Rights' approach is not primarily defended on ethical grounds. It's core justification, rather, is a realistic one - our claim is that this approach, or something like it, is needed if we're to break the global impasse over developmental equity in a climate constrained world. We put forward this new approach not because we believe that it will be readily adopted as themore » foundation of the post-2012 regime. Rather, we intend it as a standard of comparison, a reference framework that marks out the steps that must be part of an effective climate regime, while refusing to prejudge which of them will or will not ultimately be deemed politically acceptable. Against this reference framework, given regime proposals can be measured to determine how realistic they are, from the standpoint of genuinely addressing the North/South impasse and having a chance of preventing a climate catastrophe. The climate crisis, as most everyone in the climate community knows, is upon us. Still, the pace of our response has been profoundly inadequate, so this paper will begin with the blunt truth. The science now tells us that we're pushing beyond mere 'dangerous anthropogenic interference with the climate system', and are rather on the verge of committing to catastrophic interference.« less

The United Nations and Climate Change: Legal and Policy Developments

NASA Astrophysics Data System (ADS)

Bunn, Isabella D.

2009-07-01

The Secretary-General of the United Nations, Ban Ki-moon, has declared that climate change is "the defining challenge of our times." Climate change trends indicate increasingly severe negative impacts on the majority of countries, with disproportionate effects on poor and vulnerable populations. The scientific reports of the Intergovernmental Panel on Climate Change (IPCC), as well as the negotiations under the UN Framework Convention on Climate Change (UNFCCC), have placed the issue on the forefront of the international agenda. This article examines how climate change is shaping legal and policy developments in five key areas of UN responsibility: international law, humanitarian affairs, human rights, development, and peace and security. It concludes with some observations about high-level efforts to coordinate the response of multilateral institutions, the changing stance of the US government, and the role of environmental protection in addressing the current global economic crisis.

Hanseniaspora nodinigri, a new yeast species found in black knots (Dibotryon morbosum) of Prunus virginiana.

PubMed

Lachance, M A

1981-07-01

The new yeast species Hanseniaspora nodinigri is described to accommodate members of the genus Hanseniaspora that are unable to assimilate glucono-sigma-lactone and isolated from stromatal tissue of black knots (Dobotryon morbosum) of chokecherry, Prunus virginiana. The newly described taxon shows much resemblance, by other criteria, to H. vineae van der Walt et Tscheuschner and H. osmophila (Niehaus) Phaff, Miller et Shifrine.

Development of Climate Change Adaptation Platform using Spatial Information

NASA Astrophysics Data System (ADS)

Lee, J.; Oh, K. Y.; Lee, M. J.; Han, W. J.

2014-12-01

Climate change adaptation has attracted growing attention with the recent extreme weather conditions that affect people around the world. More and more countries, including the Republic of Korea, have begun to hatch adaptation plan to resolve these matters of great concern. They all, meanwhile, have mentioned that it should come first to integrate climate information in all analysed areas. That's because climate information is not independently made through one source; that is to say, the climate information is connected one another in a complicated way. That is the reason why we have to promote integrated climate change adaptation platform before setting up climate change adaptation plan. Therefore, the large-scaled project has been actively launched and worked on. To date, we researched 620 literatures and interviewed 51 government organizations. Based on the results of the researches and interviews, we obtained 2,725 impacts about vulnerability assessment information such as Monitoring and Forecasting, Health, Disaster, Agriculture, Forest, Water Management, Ecosystem, Ocean/Fisheries, Industry/Energy. Among 2,725 impacts, 995 impacts are made into a database until now. This database is made up 3 sub categories like Climate-Exposure, Sensitivity, Adaptive capacity, presented by IPCC. Based on the constructed database, vulnerability assessments were carried out in order to evaluate climate change capacity of local governments all over the country. These assessments were conducted by using web-based vulnerability assessment tool which was newly developed through this project. These results have shown that, metropolitan areas like Seoul, Pusan, Inchon, and so on have high risks more than twice than rural areas. Acknowledgements: The authors appreciate the support that this study has received from "Development of integrated model for climate change impact and vulnerability assessment and strengthening the framework for model implementation ", an initiative of the

78 FR 56866 - National Climate Assessment and Development Advisory Committee (NCADAC)

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-16

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Climate Assessment... open meeting. SUMMARY: The National Climate Assessment and Development Advisory Committee (NCADAC) was... synthesize and summarize the science and information pertaining to current and future impacts of climate...

Development and Validation of an Instrument for Assessing Climate Change Knowledge and Perceptions: The Climate Stewardship Survey (CSS)

ERIC Educational Resources Information Center

Walker, Scott L.; McNeal, Karen S.

2013-01-01

The Climate Stewardship Survey (CSS) was developed to measure knowledge and perceptions of global climate change, while also considering information sources that respondents 'trust.' The CSS was drafted using a three-stage approach: development of salient scales, writing individual items, and field testing and analyses. Construct validity and…

Development of hi-resolution regional climate scenarios in Japan by statistical downscaling

NASA Astrophysics Data System (ADS)

Dairaku, K.

2016-12-01

Climate information and services for Impacts, Adaptation and Vulnerability (IAV) Assessments are of great concern. To meet with the needs of stakeholders such as local governments, a Japan national project, Social Implementation Program on Climate Change Adaptation Technology (SI-CAT), launched in December 2015. It develops reliable technologies for near-term climate change predictions. Multi-model ensemble regional climate scenarios with 1km horizontal grid-spacing over Japan are developed by using CMIP5 GCMs and a statistical downscaling method to support various municipal adaptation measures appropriate for possible regional climate changes. A statistical downscaling method, Bias Correction Spatial Disaggregation (BCSD), is employed to develop regional climate scenarios based on CMIP5 RCP8.5 five GCMs (MIROC5, MRI-CGCM3, GFDL-CM3, CSIRO-Mk3-6-0, HadGEM2-ES) for the periods of historical climate (1970-2005) and near future climate (2020-2055). Downscaled variables are monthly/daily precipitation and temperature. File format is NetCDF4 (conforming to CF1.6, HDF5 compression). Developed regional climate scenarios will be expanded to meet with needs of stakeholders and interface applications to access and download the data are under developing. Statistical downscaling method is not necessary to well represent locally forced nonlinear phenomena, extreme events such as heavy rain, heavy snow, etc. To complement the statistical method, dynamical downscaling approach is also combined and applied to some specific regions which have needs of stakeholders. The added values of statistical/dynamical downscaling methods compared with parent GCMs are investigated.

Development of risk-based air quality management strategies under impacts of climate change.

PubMed

Liao, Kuo-Jen; Amar, Praveen; Tagaris, Efthimios; Russell, Armistead G

2012-05-01

Climate change is forecast to adversely affect air quality through perturbations in meteorological conditions, photochemical reactions, and precursor emissions. To protect the environment and human health from air pollution, there is an increasing recognition of the necessity of developing effective air quality management strategies under the impacts of climate change. This paper presents a framework for developing risk-based air quality management strategies that can help policy makers improve their decision-making processes in response to current and future climate change about 30-50 years from now. Development of air quality management strategies under the impacts of climate change is fundamentally a risk assessment and risk management process involving four steps: (1) assessment of the impacts of climate change and associated uncertainties; (2) determination of air quality targets; (3) selections of potential air quality management options; and (4) identification of preferred air quality management strategies that minimize control costs, maximize benefits, or limit the adverse effects of climate change on air quality when considering the scarcity of resources. The main challenge relates to the level of uncertainties associated with climate change forecasts and advancements in future control measures, since they will significantly affect the risk assessment results and development of effective air quality management plans. The concept presented in this paper can help decision makers make appropriate responses to climate change, since it provides an integrated approach for climate risk assessment and management when developing air quality management strategies. Development of climate-responsive air quality management strategies is fundamentally a risk assessment and risk management process. The risk assessment process includes quantification of climate change impacts on air quality and associated uncertainties. Risk management for air quality under the impacts of

Inspiring Climate Education Excellence (ICEE): Developing self-directed professional development modules for secondary science teachers

NASA Astrophysics Data System (ADS)

Buhr, S. M.; Lynds, S. E.; McCaffrey, M. S.; Morton, E.

2010-12-01

Inspiring Climate Education Excellence (ICEE) is a NASA-funded project to develop online course modules and self-directed learning resources aligned with the Essential Principles of Climate Science. Following a national needs assessment survey and a face to face workshop to pilot test topics, a suite of online modules is being developed suitable for self-directed learning by secondary science teachers. Modules are designed around concepts and topics in which teachers express the most interest and need for instruction. Module design also includes attention to effective teaching strategies, such as awareness of student misconceptions, strategies for forestalling controversy and advice from master teachers on implementation and curriculum development. The resources are being developed in partnership with GLOBE, and the National Science Digital Library (NSDL) and is informed by the work of the Climate Literacy and Energy Awareness Network (CLEAN) project. ICEE will help to meet the professional development needs of teachers, including those participating in the GLOBE Student Climate Research Campaign. Modules and self-directed learning resources will be developed and disseminated in partnership with the National Science Digital Library (NSDL). This presentation introduces the needs assessment and pilot workshop data upon which the modules are based, and describes the modules that are available and in development.

77 FR 61574 - National Climate Assessment and Development Advisory Committee; Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-10

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Climate Assessment... National Climate Assessment and Development Advisory Committee (NCADAC). DATES: Time and Date: The meeting... to dial into the call. Please check the National Climate Assessment Web site for additional...

77 FR 56191 - National Climate Assessment and Development Advisory Committee (NCADAC)

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-12

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Climate Assessment... National Climate Assessment and Development Advisory Committee (NCADAC). DATES: The meeting will be held... dial into the call. Please check the National Climate Assessment Web site for additional information at...

NMR analysis reveals a wealth of metabolites in root-knot nematode resistant roots of Citrullus amarus watermelon plants

USDA-ARS?s Scientific Manuscript database

Citrullus amarus (CA) (previously known as Citrullus lanatus var. citroides) accessions collected in southern Africa are known to have resistance to root-knot nematodes (RKN) and are suitable rootstocks for grafted watermelon. A comparative metabolomics study was performed to identify unique metabol...

Influence of root exudates and soil on attachment of Pasteuria penetrans to root-knot nematode Meloidogyne arenaria

USDA-ARS?s Scientific Manuscript database

Pasteuria penetrans is a parasite of root-knot nematode (Meloidogyne spp.). Spores of P. penetrans attach to the cuticle of second stage juvenile (J2) and sterilize infected female. This study looked at different factors that influence spore attachment of P. penetrans to M. arenaria. Incubating J2 ...

A new method for the adjustment of neochordal length: the adjustable slip knot technique.

PubMed

Yano, Mitsuhiro; Sakaguchi, Syuuhei; Furukawa, Kohji; Nakamura, Eisaku

2015-08-01

The use of expanded polytetrafluoroethylene (ePTFE) sutures for the correction of mitral valve prolapse has become a standardized procedure. Adjustment of neochordal length is crucial to the efficacy of this technique. Various methods have been described for this purpose; however, the fine adjustment of neochordal length is technically challenging. We describe a simple and effective technique for the implantation of neochordae, which we have termed the 'adjustable slip knot technique'. The first step of this technique is reinforcement of the papillary muscle by a Teflon pledget with or without polytetrafluoroethylene (CV-4) loops. The second step is the formation of a neochordal loop by introducing an ePTFE suture between the affected mitral leaflet and the papillary muscle or ePTFE loops. The third step is the adjustment of the length of neochordae. The formation of a slip knot in one arm of the ePTFE suture is the pivot of this technique. The neochordal loop can be constricted by the application of tension to one arm of the suture. We applied this technique in 5 patients with satisfactory results. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Climate Change and Food Security: Health Impacts in Developed Countries

PubMed Central

Hooper, Lee; Abdelhamid, Asmaa; Bentham, Graham; Boxall, Alistair B.A.; Draper, Alizon; Fairweather-Tait, Susan; Hulme, Mike; Hunter, Paul R.; Nichols, Gordon; Waldron, Keith W.

2012-01-01

Background: Anthropogenic climate change will affect global food production, with uncertain consequences for human health in developed countries. Objectives: We investigated the potential impact of climate change on food security (nutrition and food safety) and the implications for human health in developed countries. Methods: Expert input and structured literature searches were conducted and synthesized to produce overall assessments of the likely impacts of climate change on global food production and recommendations for future research and policy changes. Results: Increasing food prices may lower the nutritional quality of dietary intakes, exacerbate obesity, and amplify health inequalities. Altered conditions for food production may result in emerging pathogens, new crop and livestock species, and altered use of pesticides and veterinary medicines, and affect the main transfer mechanisms through which contaminants move from the environment into food. All these have implications for food safety and the nutritional content of food. Climate change mitigation may increase consumption of foods whose production reduces greenhouse gas emissions. Impacts may include reduced red meat consumption (with positive effects on saturated fat, but negative impacts on zinc and iron intake) and reduced winter fruit and vegetable consumption. Developed countries have complex structures in place that may be used to adapt to the food safety consequences of climate change, although their effectiveness will vary between countries, and the ability to respond to nutritional challenges is less certain. Conclusions: Climate change will have notable impacts upon nutrition and food safety in developed countries, but further research is necessary to accurately quantify these impacts. Uncertainty about future impacts, coupled with evidence that climate change may lead to more variable food quality, emphasizes the need to maintain and strengthen existing structures and policies to regulate

Climate change and food security: health impacts in developed countries.

PubMed

Lake, Iain R; Hooper, Lee; Abdelhamid, Asmaa; Bentham, Graham; Boxall, Alistair B A; Draper, Alizon; Fairweather-Tait, Susan; Hulme, Mike; Hunter, Paul R; Nichols, Gordon; Waldron, Keith W

2012-11-01

Anthropogenic climate change will affect global food production, with uncertain consequences for human health in developed countries. We investigated the potential impact of climate change on food security (nutrition and food safety) and the implications for human health in developed countries. Expert input and structured literature searches were conducted and synthesized to produce overall assessments of the likely impacts of climate change on global food production and recommendations for future research and policy changes. Increasing food prices may lower the nutritional quality of dietary intakes, exacerbate obesity, and amplify health inequalities. Altered conditions for food production may result in emerging pathogens, new crop and livestock species, and altered use of pesticides and veterinary medicines, and affect the main transfer mechanisms through which contaminants move from the environment into food. All these have implications for food safety and the nutritional content of food. Climate change mitigation may increase consumption of foods whose production reduces greenhouse gas emissions. Impacts may include reduced red meat consumption (with positive effects on saturated fat, but negative impacts on zinc and iron intake) and reduced winter fruit and vegetable consumption. Developed countries have complex structures in place that may be used to adapt to the food safety consequences of climate change, although their effectiveness will vary between countries, and the ability to respond to nutritional challenges is less certain. Climate change will have notable impacts upon nutrition and food safety in developed countries, but further research is necessary to accurately quantify these impacts. Uncertainty about future impacts, coupled with evidence that climate change may lead to more variable food quality, emphasizes the need to maintain and strengthen existing structures and policies to regulate food production, monitor food quality and safety, and

Linking topology of tethered polymer rings with applications to chromosome segregation and estimation of the knotting length.

PubMed

Marko, John F

2009-05-01

The Gauss linking number (Ca) of two flexible polymer rings which are tethered to one another is investigated. For ideal random walks, mean linking-squared varies with the square root of polymer length while for self-avoiding walks, linking-squared increases logarithmically with polymer length. The free-energy cost of linking of polymer rings is therefore strongly dependent on degree of self-avoidance, i.e., on intersegment excluded volume. Scaling arguments and numerical data are used to determine the free-energy cost of fixed linking number in both the fluctuation and large-Ca regimes; for ideal random walks, for |Ca|>N;{1/4} , the free energy of catenation is found to grow proportional, variant|Ca/N;{1/4}|;{4/3} . When excluded volume interactions between segments are present, the free energy rapidly approaches a linear dependence on Gauss linking (dF/dCa approximately 3.7k_{B}T) , suggestive of a novel "catenation condensation" effect. These results are used to show that condensation of long entangled polymers along their length, so as to increase excluded volume while decreasing number of statistical segments, can drive disentanglement if a mechanism is present to permit topology change. For chromosomal DNA molecules, lengthwise condensation is therefore an effective means to bias topoisomerases to eliminate catenations between replicated chromatids. The results for mean-square catenation are also used to provide a simple approximate estimate for the "knotting length," or number of segments required to have a knot along a single circular polymer, explaining why the knotting length ranges from approximately 300 for an ideal random walk to 10;{6} for a self-avoiding walk.

Soliton stability in some knot soliton models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adam, C.; Sanchez-Guillen, J.; Wereszczynski, A.

2007-02-15

We study the issue of stability of static solitonlike solutions in some nonlinear field theories which allow for knotted field configurations. Concretely, we investigate the Aratyn-Ferreira-Zimerman model [Phys. Lett. B 456, 162 (1999); Phys. Rev. Lett. 83, 1723 (1999)], based on a Lagrangian quartic in first derivatives with infinitely many conserved currents, for which infinitely many soliton solutions are known analytically. For this model we find that sectors with different (integer) topological charges (Hopf index) are not separated by an infinite energy barrier. Further, if variations which change the topological charge are allowed, then the static solutions are not evenmore » critical points of the energy functional. We also explain why soliton solutions can exist at all, in spite of these facts. In addition, we briefly discuss the Nicole model [J. Phys. G 4, 1363 (1978)], which is based on a sigma-model-type Lagrangian. For the Nicole model we find that different topological sectors are separated by an infinite energy barrier.« less

76 FR 25309 - National Climate Assessment and Development Advisory Committee (NCADAC)

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-04

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Climate Assessment... meeting of the DOC NOAA National Climate Assessment and Development Advisory Committee (NCADAC). The... available at a location to be determined. Please check the National Climate Assessment Web site for this...

77 FR 64491 - National Climate Assessment and Development Advisory Committee (NCADAC)

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2012-10-22

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Climate Assessment... National Climate Assessment and Development Advisory Committee (NCADAC). Time and Date: The meeting will be... One Veterans Place Silver Spring, MD 20910. Please check the National Climate Assessment Web site for...

77 FR 20794 - National Climate Assessment and Development Advisory Committee (NCADAC)

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2012-04-06

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Climate Assessment.... SUMMARY: This notice announces the selection of the authors for the report of the next National Climate Assessment by the National Climate Assessment and Development Advisory Committee (NCADAC). The next National...

Developing Climate Change Literacy With the Humanities: A Narrative Approach

NASA Astrophysics Data System (ADS)

Siperstein, S.

2015-12-01

Teaching the science and policy of climate change is necessary but insufficient for helping students to develop a robust climate literacy. Climate change educators must also teach students how to evaluate historical trends, to unpack the assumptions in shared cultural narratives, to grapple with ethical dilemmas, and more generally to traverse the turbulence of feeling that is a hallmark of living in a time of global climate chaos. In short, climate literacy must include the skills and strategies of the humanities, and specifically literary and cultural studies. After providing an overview of how literary and cultural studies scholars from around the world are developing innovative pedagogical methods for addressing climate change (drawing on the presenter's experience editing the forthcoming volume Teaching Climate Change in the Humanities), the presentation will then report on a specific Literary Genres course taught at the University of Oregon. The course, offered to undergraduate non-majors who entered the class with little or no knowledge of climate change, constituted a case study of action research into the transdisciplinary teaching of climate change. The presentation will thus draw on quantitative course assessments, student coursework, and the instructor's own experiences in arguing that three key narratives underpin the work we do as multidisciplinary climate change educators: narratives of observation, narratives of speculation, and narratives of conversion. That is, we guide students through the processes of witnessing climate change, imagining more just and sustainable futures, and by so doing, transforming themselves and their communities. In the particular Literary Genres course under consideration, students used the tools of literary and cultural studies first to analyze existing versions of these narratives and then to compose their own versions of these narratives based on their local communities and ecologies. In the context of multidisciplinary

78 FR 64481 - National Climate Assessment and Development Advisory Committee (NCADAC)

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2013-10-29

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78 FR 51711 - National Climate Assessment and Development Advisory Committee (NCADAC)

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2013-08-21

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78 FR 21598 - National Climate Assessment and Development Advisory Committee (NCADAC)

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-11

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Development of climate risk services under climate change scenarios in the North Adriatic coast (Italy).

NASA Astrophysics Data System (ADS)

Valentina, Gallina; Silvia, Torresan; Anna, Sperotto; Elisa, Furlan; Andrea, Critto; Antonio, Marcomini

2014-05-01

Nowadays, the challenge for coastal stakeholders and decision makers is to incorporate climate change in land and policy planning in order to ensure a sustainable integrated coastal zone management aimed at preserve coastal environments and socio-economic activities. Consequently, an increasing amount of information on climate variability and its impact on human and natural ecosystem is requested. Climate risk services allows to bridge the gap between climate experts and decision makers communicating timely science-based information about impacts and risks related to climate change that could be incorporated into land planning, policy and practice. Within the CLIM-RUN project (FP7), a participatory Regional Risk Assessment (RRA) methodology was applied for the evaluation of water-related hazards in coastal areas (i.e. pluvial flood and sea-level rise inundation risks) taking into consideration future climate change scenarios in the case study of the North Adriatic Sea for the period 2040-2050. Specifically, through the analysis of hazard, exposure, vulnerability and risk and the application of Multi-Criteria Decision Analysis (MCDA), the RRA methodology allowed to identify and prioritize targets (i.e. residential and commercial-industrial areas, beaches, infrastructures, wetlands, agricultural typology) and sub-areas that are more likely to be affected by pluvial flood and sea-level rise impacts in the same region. From the early stages of the climate risk services development and application, the RRA followed a bottom-up approach taking into account the needs, knowledge and perspectives of local stakeholders dealing with the Integrated Coastal Zone Management (ICZM), by means of questionnaires, workshops and focus groups organized within the project. Specifically, stakeholders were asked to provide their needs in terms of time scenarios, geographical scale and resolution, choice of receptors, vulnerability factors and thresholds that were considered in the

Development, malaria and adaptation to climate change: a case study from India.

PubMed

Garg, Amit; Dhiman, R C; Bhattacharya, Sumana; Shukla, P R

2009-05-01

India has reasons to be concerned about climate change. Over 650 million people depend on climate-sensitive sectors, such as rain-fed agriculture and forestry, for livelihood and over 973 million people are exposed to vector borne malarial parasites. Projection of climatic factors indicates a wider exposure to malaria for the Indian population in the future. If precautionary measures are not taken and development processes are not managed properly some developmental activities, such as hydro-electric dams and irrigation canal systems, may also exacerbate breeding grounds for malaria. This article integrates climate change and developmental variables in articulating a framework for integrated impact assessment and adaptation responses, with malaria incidence in India as a case study. The climate change variables include temperature, rainfall, humidity, extreme events, and other secondary variables. Development variables are income levels, institutional mechanisms to implement preventive measures, infrastructure development that could promote malarial breeding grounds, and other policies. The case study indicates that sustainable development variables may sometimes reduce the adverse impacts on the system due to climate change alone, while it may sometimes also exacerbate these impacts if the development variables are not managed well and therefore they produce a negative impact on the system. The study concludes that well crafted and well managed developmental policies could result in enhanced resilience of communities and systems, and lower health impacts due to climate change.

Development, Malaria and Adaptation to Climate Change: A Case Study from India

NASA Astrophysics Data System (ADS)

Garg, Amit; Dhiman, R. C.; Bhattacharya, Sumana; Shukla, P. R.

2009-05-01

India has reasons to be concerned about climate change. Over 650 million people depend on climate-sensitive sectors, such as rain-fed agriculture and forestry, for livelihood and over 973 million people are exposed to vector borne malarial parasites. Projection of climatic factors indicates a wider exposure to malaria for the Indian population in the future. If precautionary measures are not taken and development processes are not managed properly some developmental activities, such as hydro-electric dams and irrigation canal systems, may also exacerbate breeding grounds for malaria. This article integrates climate change and developmental variables in articulating a framework for integrated impact assessment and adaptation responses, with malaria incidence in India as a case study. The climate change variables include temperature, rainfall, humidity, extreme events, and other secondary variables. Development variables are income levels, institutional mechanisms to implement preventive measures, infrastructure development that could promote malarial breeding grounds, and other policies. The case study indicates that sustainable development variables may sometimes reduce the adverse impacts on the system due to climate change alone, while it may sometimes also exacerbate these impacts if the development variables are not managed well and therefore they produce a negative impact on the system. The study concludes that well crafted and well managed developmental policies could result in enhanced resilience of communities and systems, and lower health impacts due to climate change.

Developing NOAA's Climate Data Records From AVHRR and Other Data

NASA Astrophysics Data System (ADS)

Privette, J. L.; Bates, J. J.; Kearns, E. J.

2010-12-01

As part of the provisional NOAA Climate Service, NOAA is providing leadership in the development of authoritative, measurement-based information on climate change and variability. NOAA’s National Climatic Data Center (NCDC) recently initiated a satellite Climate Data Record Program (CDRP) to provide sustained and objective climate information derived from meteorological satellite data that NOAA has collected over the past 30+ years - particularly from its Polar Orbiting Environmental Satellites (POES) program. These are the longest sustained global measurement records in the world and represent billions of dollars of investment. NOAA is now applying advanced analysis methods -- which have improved remarkably over the last decade -- to the POES AVHRR and other instrument data. Data from other satellite programs, including NASA and international research programs and the Defense Meteorological Satellite Program (DMSP), are also being used. This process will unravel the underlying climate trend and variability information and return new value from the records. In parallel, NCDC will extend these records by applying the same methods to present-day and future satellite measurements, including the Joint Polar Satellite System (JPSS) and Jason-3. In this presentation, we will describe the AVHRR-related algorithm development activities that CDRP recently selected and funded through open competitions. We will particularly discuss some of the technical challenges related to adapting and using AVHRR algorithms with the VIIRS data that should become available with the launch of the NPOESS Preparatory Project (NPP) satellite in early 2012. We will also describe IT system development activities that will provide data processing and reprocessing, storage and management. We will also outline the maturing Program framework, including the strategies for coding and development standards, community reviews, independent program oversight, and research-to-operations algorithm

Development and Validation of a Safety Climate Scale for Manufacturing Industry

PubMed Central

Ghahramani, Abolfazl; Khalkhali, Hamid R.

2015-01-01

Background This paper describes the development of a scale for measuring safety climate. Methods This study was conducted in six manufacturing companies in Iran. The scale developed through conducting a literature review about the safety climate and constructing a question pool. The number of items was reduced to 71 after performing a screening process. Results The result of content validity analysis showed that 59 items had excellent item content validity index (≥ 0.78) and content validity ratio (> 0.38). The exploratory factor analysis resulted in eight safety climate dimensions. The reliability value for the final 45-item scale was 0.96. The result of confirmatory factor analysis showed that the safety climate model is satisfactory. Conclusion This study produced a valid and reliable scale for measuring safety climate in manufacturing companies. PMID:26106508

Development of ALARO-Climate regional climate model for a very high resolution

NASA Astrophysics Data System (ADS)

Skalak, Petr; Farda, Ales; Brozkova, Radmila; Masek, Jan

2013-04-01

ALARO-Climate is a new regional climate model (RCM) derived from the ALADIN LAM model family. It is based on the numerical weather prediction model ALARO and developed at the Czech Hydrometeorological Institute. The model is expected to able to work in the so called "grey zone" physics (horizontal resolution of 4 - 7 km) and at the same time retain its ability to be operated in resolutions in between 20 and 50 km, which are typical for contemporary generation of regional climate models. Here we present the main features of the RCM ALARO-Climate and results of the first model simulations on longer time-scales (1961-1990). The model was driven by the ERA-40/Interim re-analyses and run on the large pan-European integration domain ("ENSEMBLES / Euro-Cordex domain") with spatial resolution of 25 km. The simulated model climate was compared with the gridded observation of air temperature (mean, maximum, minimum) and precipitation from the E-OBS version 7 dataset. The validation of the first ERA-40 simulation has revealed significant cold biases in all seasons (between -4 and -2 °C) and overestimation of precipitation on 20% to 60% in the selected Central Europe target area (0° - 30° eastern longitude ; 40° - 60° northern latitude). The consequent adaptations in the model and their effect on the simulated properties of climate variables are illustrated. Acknowledgements: This study was performed within the frame of projects ALARO (project P209/11/2405 sponsored by the Czech Science Foundation) and CzechGlobe Centre (CZ.1.05/1.1.00/02.0073). The partial support was also provided under the projects P209-11-0956 of the Czech Science Foundation and CZ.1.07/2.4.00/31.0056 (Operational Programme of Education for Competitiveness of Ministry of Education, Youth and Sports of the Czech Republic).

Southern Foresters' Perceptions of Climate Change: Implications for Educational Program Development

ERIC Educational Resources Information Center

Boby, Leslie; Hubbard, William; Megalos, Mark; Morris, Hilary L. C.

2016-01-01

An understanding of foresters' perceptions of climate change is important for developing effective educational programs on adaptive forest management. We surveyed 1,398 foresters in the southern United States regarding their perceptions of climate change, observations and concerns about climatic and forest conditions, and knowledge of and interest…

76 FR 44307 - National Climate Assessment and Development Advisory Committee (NCADAC)

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-25

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration (NOAA) National Climate...: Notice of open meeting. SUMMARY: The National Climate Assessment and Development Advisory Committee... impacts of climate. Time and Date: The meeting will be held August 16 and 17, 2011, from 9 a.m to 6 p.m...

Effect of Emamectin Benzoate on Root-Knot Nematodes and Tomato Yield

PubMed Central

Cheng, Xingkai; Liu, Xiumei; Wang, Hongyan; Ji, Xiaoxue; Wang, Kaiyun; Wei, Min; Qiao, Kang

2015-01-01

Southern root-knot nematode (Meloidogyne incognita) is an obligate, sedentary endoparasite of more than 3000 plant species, that causes heavy economic losses and limit the development of protected agriculture of China. As a biological pesticide, emamectin benzoate has effectively prevented lepidopteran pests; however, its efficacy to control M. incognita remains unknown. The purpose of the present study was to test soil application of emamectin benzoate for management of M. incognita in laboratory, greenhouse and field trials. Laboratory results showed that emamectin benzoate exhibited high toxicity to M. incognita, with LC50 and LC90 values 3.59 and 18.20 mg L-1, respectively. In greenhouse tests, emamectin benzoate soil application offered good efficacy against M. incognita while maintaining excellent plant growth. In field trials, emamectin benzoate provided control efficacy against M. incognita and resulted in increased tomato yields. Compared with the untreated control, there was a 36.5% to 81.3% yield increase obtained from all treatments and the highest yield was received from the highest rate of emamectin benzoate. The results confirmed that emamectin benzoate has enormous potential for the control of M. incognita in tomato production in China. PMID:26509680

Effect of Emamectin Benzoate on Root-Knot Nematodes and Tomato Yield.

PubMed

Cheng, Xingkai; Liu, Xiumei; Wang, Hongyan; Ji, Xiaoxue; Wang, Kaiyun; Wei, Min; Qiao, Kang

2015-01-01

Southern root-knot nematode (Meloidogyne incognita) is an obligate, sedentary endoparasite of more than 3000 plant species, that causes heavy economic losses and limit the development of protected agriculture of China. As a biological pesticide, emamectin benzoate has effectively prevented lepidopteran pests; however, its efficacy to control M. incognita remains unknown. The purpose of the present study was to test soil application of emamectin benzoate for management of M. incognita in laboratory, greenhouse and field trials. Laboratory results showed that emamectin benzoate exhibited high toxicity to M. incognita, with LC50 and LC90 values 3.59 and 18.20 mg L(-1), respectively. In greenhouse tests, emamectin benzoate soil application offered good efficacy against M. incognita while maintaining excellent plant growth. In field trials, emamectin benzoate provided control efficacy against M. incognita and resulted in increased tomato yields. Compared with the untreated control, there was a 36.5% to 81.3% yield increase obtained from all treatments and the highest yield was received from the highest rate of emamectin benzoate. The results confirmed that emamectin benzoate has enormous potential for the control of M. incognita in tomato production in China.

Development of A Dust Climate Indicator for the US National Climate Assessment

NASA Astrophysics Data System (ADS)

Tong, D.; Wang, J. X. L.; Gill, T. E.; Van Pelt, S.; Kim, D.

2016-12-01

Dust activity is a relatively simple but practical indicator to document the response of dryland ecosystems to climate change, making it an integral part of the National Climate Assessment (NCA). We present here a multi-agency collaboration that aims at developing a suite of dust climate indicators to document and monitor the long-term variability and trend of dust storm activity in the western United States. Recent dust observations have revealed rapid intensification of dust storm activity in the western United States. This trend is also closely correlated with a rapid increase in dust deposition in rainwater and "valley fever" hospitalization in southwestern states. It remains unclear, however, if such a trend, when enhanced by predicted warming and rainfall oscillation in the Southwest, will result in irreversible environmental development such as desertification or even another "Dust Bowl". Based on continuous ground aerosol monitoring, we have reconstructed a long-term dust storm climatology in the western United States. We report here direct evidence of rapid intensification of dust storm activity over US deserts in the past decades (1990 to 2013), in contrast to the decreasing trends in Asia and Africa. The US trend is spatially and temporally correlated with incidences of valley fever, an infectious disease caused by soil-dwelling fungus that has increased eight-fold in the past decade. We further investigate the linkage between dust variations and possible climate drivers and find that the regional dust trends are likely driven by large-scale variations of sea surface temperature in the Pacific Ocean, with the strongest correlation with the Pacific Decadal Oscillation (PDO). Future study will explore the link between the temporal and spatial trends of increase in dustiness and vegetation change in southwestern semi-arid and arid ecosystems.

Development of an Empirically-Based Conditional Learning Progression for Climate Change

ERIC Educational Resources Information Center

Breslyn, Wayne; Drewes, Andrea; McGinnis, J. Randy; Hestness, Emily; Mouza, Chrystalla

2017-01-01

Climate change encompasses a broad and complex set of concepts that is often challenging for students and educators. Using a learning progressions (LPs) knowledge system, we developed a LP that described student learning of climate change. In this exploratory study, we present findings from written assessments of climate change (n = 294) and…

Developing A Positive School Climate. Newsletter

ERIC Educational Resources Information Center

Center for Comprehensive School Reform and Improvement, 2009

2009-01-01

Decades of research support the role of a positive school climate on teaching and learning. This newsletter takes a look at the topic of school climate and sets out to determine: (1) What is school climate? (2) How can schools assess their school climate? (3) What are some practical examples of how schools are assessing school climate? and (4)…

Regional Climate Change and Development of Public Health Decision Aids

NASA Astrophysics Data System (ADS)

Hegedus, A. M.; Darmenova, K.; Grant, F.; Kiley, H.; Higgins, G. J.; Apling, D.

2011-12-01

According to the World Heath Organization (WHO) climate change is a significant and emerging threat to public health, and changes the way we must look at protecting vulnerable populations. Worldwide, the occurrence of some diseases and other threats to human health depend predominantly on local climate patterns. Rising average temperatures, in combination with changing rainfall patterns and humidity levels, alter the lifecycle and regional distribution of certain disease-carrying vectors, such as mosquitoes, ticks and rodents. In addition, higher surface temperatures will bring heat waves and heat stress to urban regions worldwide and will likely increase heat-related health risks. A growing body of scientific evidence also suggests an increase in extreme weather events such as floods, droughts and hurricanes that can be destructive to human health and well-being. Therefore, climate adaptation and health decision aids are urgently needed by city planners and health officials to determine high risk areas, evaluate vulnerable populations and develop public health infrastructure and surveillance systems. To address current deficiencies in local planning and decision making with respect to regional climate change and its effect on human health, our research is focused on performing a dynamical downscaling with the Weather Research and Forecasting (WRF) model to develop decision aids that translate the regional climate data into actionable information for users. WRF model is initialized with the Max Planck Institute European Center/Hamburg Model version 5 (ECHAM5) General Circulation Model simulations forced with the Special Report on Emissions (SRES) A1B emissions scenario. Our methodology involves development of climatological indices of extreme weather, quantifying the risk of occurrence of water/rodent/vector-borne diseases as well as developing various heat stress related decision aids. Our results indicate that the downscale simulations provide the necessary

Empowering America's Communities to Prepare for the Effects of Climate Change: Developing Actionable Climate Science Under the President's Climate Action Plan

NASA Astrophysics Data System (ADS)

Duffy, P. B.; Colohan, P.; Driggers, R.; Herring, D.; Laurier, F.; Petes, L.; Ruffo, S.; Tilmes, C.; Venkataraman, B.; Weaver, C. P.

2014-12-01

Effective adaptation to impacts of climate change requires best-available information. To be most useful, this information should be easily found, well-documented, and translated into tools that decision-makers use and trust. To meet these needs, the President's Climate Action Plan includes efforts to develop "actionable climate science". The Climate Data Initiative (CDI) leverages the Federal Government's extensive, open data resources to stimulate innovation and private-sector entrepreneurship in support of actions to prepare for climate change. The Initiative forges commitments and partnerships from the private, NGO, academic, and public sectors to create data-driven tools. Open data from Federal agencies to support this innovation is available on Climate.Data.gov, initially focusing on coastal flooding but soon to expand to topics including food, energy, water, energy, transportation, and health. The Climate Resilience Toolkit (CRT) will facilitate access to data-driven resilience tools, services, and best practices, including those accessible through the CDI. The CRT will also include access to training and tutorials, case studies, engagement forums, and other information sources. The Climate Action Plan also calls for a public-private partnership on extreme weather risk, with the goal of generating improved assessments of risk from different types of extreme weather events, using methods and data that are transparent and accessible. Finally, the U.S. Global Change Research Program and associated agencies work to advance the science necessary to inform decisions and sustain assessments. Collectively, these efforts represent increased emphasis across the Federal Government on the importance of information to support climate resilience.

A climate-compatible approach to development practice by international humanitarian NGOs.

PubMed

Clarke, Matthew; de Cruz, Ian

2015-01-01

If current climate-change predictions prove accurate, non-linear change, including potentially catastrophic change, is possible and the environments in which international humanitarian NGOs operate will change figuratively and literally. This paper proposes that a new approach to development is required that takes changing climate into account. This 'climate-compatible approach' to development is a bleak shift from some of the current orthodox positions and will be a major challenge to international humanitarian NGOs working with the most vulnerable. However, it is necessary to address the challenges and context such NGOs face, and the need to be resilient and adaptive to these changes. © 2014 The Author(s). Disasters © Overseas Development Institute, 2014.

Developing a System of National Climate Assessment Indicators to Track Climate Change Impacts, Vulnerabilities, and Preparedness

NASA Astrophysics Data System (ADS)

Janetos, A. C.; Kenney, M. A.; Chen, R. S.; Arndt, D.

2012-12-01

The National Climate Assessment (NCA) is being conducted under the auspices of the U.S. Global Change Research Program (USGCRP), pursuant to the Global Change Research Act of 1990, Section 106, which requires a report to Congress every 4 years (http://globalchange.gov/what-we-do/assessment/). Part of the vision for the sustained National Climate Assessment (NCA) process is a system of physical, ecological, and societal indicators that communicate key aspects of the physical climate, climate impacts, vulnerabilities, and preparedness for the purpose of informing both decision makers and the public with scientifically valid information that is useful to inform decision-making processes such as the development and implementation of climate adaptation strategies in a particular sector or region. These indicators will be tracked as a part of ongoing assessment activities, with adjustments as necessary to adapt to changing conditions and understanding. The indicators will be reviewed and updated so that the system adapts to new information. The NCA indicator system is not intended to serve as a vehicle for documenting rigorous cause and effect relationships. It is reasonable, however, for it to serve as a guide to those factors that affect the evolution of variability and change in the climate system, the resources and sectors of concern that are affected by it, and how society chooses to respond. Different components of the end-to-end climate issue serve as categories within which to organize an end-to-end system of indicators: Greenhouse Gas Emissions and Sinks Atmospheric Composition Physical Climate Variability and Change Sectors and Resources of Concern Adaptation and Mitigation Responses This framing has several advantages. It can be used to identify the different components of the end-to-end climate issue that both decision-makers and researchers are interested in. It is independent of scale, and therefore allows the indicators themselves to be described at

Hotspots of climate change impacts in sub-Saharan Africa and implications for adaptation and development.

PubMed

Müller, Christoph; Waha, Katharina; Bondeau, Alberte; Heinke, Jens

2014-08-01

Development efforts for poverty reduction and food security in sub-Saharan Africa will have to consider future climate change impacts. Large uncertainties in climate change impact assessments do not necessarily complicate, but can inform development strategies. The design of development strategies will need to consider the likelihood, strength, and interaction of climate change impacts across biosphere properties. We here explore the spread of climate change impact projections and develop a composite impact measure to identify hotspots of climate change impacts, addressing likelihood and strength of impacts. Overlapping impacts in different biosphere properties (e.g. flooding, yields) will not only claim additional capacity to respond, but will also narrow the options to respond and develop. Regions with severest projected climate change impacts often coincide with regions of high population density and poverty rates. Science and policy need to propose ways of preparing these areas for development under climate change impacts. © 2014 John Wiley & Sons Ltd.

Urinary Catheterization in Infants: When It's Knot so Simple.

PubMed

Sheridan, David C; Burns, Beech; Mickley, Megan

2018-02-01

Pediatric fever is one of the most common presenting complaints to emergency departments (ED). While often due to a viral illness, in young children without a source the most common bacterial infection is pyelonephritis. For this reason, when no focal source can be identified a urinary specimen is recommended. In young children who are unable to urinate on demand, a straight catheter is required to obtain a sterile specimen. This is generally a benign procedure and is performed frequently in EDs. We report a case of a young girl who underwent straight bladder catheterization and was subsequently found to have a retained catheter that had become knotted in the bladder. This case report highlights a rare complication of this common procedure and describes the technique required to remove the catheter. An understanding of these issues may avoid the need for transfer to a pediatric facility or for subspecialty consultation.

The Nematicidal Effect of Camellia Seed Cake on Root-Knot Nematode Meloidogyne javanica of Banana

PubMed Central

Yang, Xiujuan; Wang, Xuan; Wang, Kang; Su, Lanxi; Li, Hongmei; Li, Rong; Shen, Qirong

2015-01-01

Suppression of root-knot nematodes is crucially important for maintaining the worldwide development of the banana industry. Growing concerns about human and environmental safety have led to the withdrawal of commonly used nematicides and soil fumigants, thus motivating the development of alternative nematode management strategies. In this study, Meloidogyne javanica was isolated, and the nematicidal effect of Camellia seed cake on this pest was investigated. The results showed that in dish experiments, Camellia seed cake extracts under low concentration (2 g/L) showed a strong nematicidal effect. After treatment for 72 h, the eggs of M. javanica were gradually dissolved, and the intestine of the juveniles gradually became indistinct. Nematicidal compounds, including saponins identified by HPLC-ESI-MS and 8 types of volatile compounds identified by GC-MS, exhibited effective nematicidal activities, especially 4-methylphenol. The pot experiments demonstrated that the application of Camellia seed cake suppressed M. javanica, and promoted the banana plant growth. This study explored an effective nematicidal agent for application in soil and revealed its potential mechanism of nematode suppression. PMID:25849382

Root-Knot and Cyst Nematodes Activate Procambium-Associated Genes in Arabidopsis Roots.

PubMed

Yamaguchi, Yasuka L; Suzuki, Reira; Cabrera, Javier; Nakagami, Satoru; Sagara, Tomomi; Ejima, Chika; Sano, Ryosuke; Aoki, Yuichi; Olmo, Rocio; Kurata, Tetsuya; Obayashi, Takeshi; Demura, Taku; Ishida, Takashi; Escobar, Carolina; Sawa, Shinichiro

2017-01-01

Developmental plasticity is one of the most striking features of plant morphogenesis, as plants are able to vary their shapes in response to environmental cues. Biotic or abiotic stimuli often promote organogenesis events in plants not observed under normal growth conditions. Root-knot nematodes (RKNs) are known to parasitize multiple species of rooting plants and to induce characteristic tissue expansion called galls or root-knots on the roots of their hosts by perturbing the plant cellular machinery. Galls contain giant cells (GCs) and neighboring cells, and the GCs are a source of nutrients for the parasitizing nematode. Highly active cell proliferation was observed in galls. However, the underlying mechanisms that regulate the symptoms triggered by the plant-nematode interaction have not yet been elucidated. In this study, we deciphered the molecular mechanism of gall formation with an in vitro infection assay system using RKN Meloidogyne incognita , and the model plant Arabidopsis thaliana. By taking advantages of this system, we performed next-generation sequencing-based transcriptome profiling, and found that the expression of procambium identity-associated genes were enriched during gall formation. Clustering analyses with artificial xylogenic systems, together with the results of expression analyses of the candidate genes, showed a significant correlation between the induction of gall cells and procambium-associated cells. Furthermore, the promoters of several procambial marker genes such as ATHB8 , TDR and WOX4 were activated not only in M. incognita -induced galls, but similarly in M. javanica induced-galls and Heterodera schachtii -induced syncytia. Our findings suggest that phytoparasitic nematodes modulate the host's developmental regulation of the vascular stem cells during gall formation.

77 FR 17406 - National Climate Assessment and Development Advisory Committee (NCADAC) Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-26

... DEPARTMENT OF COMMERCE National Climate Assessment and Development Advisory Committee (NCADAC... sets forth the schedule and proposed agenda of a forthcoming meeting of the DoC NOAA National Climate... Pennsylvania Avenue NW., Washington, DC 20006. Please check the National Climate Assessment Web site for...

Developing a climate-based risk map of fascioliasis outbreaks in Iran.

PubMed

Halimi, Mansour; Farajzadeh, Manuchehr; Delavari, Mahdi; Arbabi, Mohsen

2015-01-01

The strong relationship between climate and fascioliasis outbreaks enables the development of climate-based models to estimate the potential risk of fascioliasis outbreaks. This work aims to develop a climate-based risk map of fascioliasis outbreaks in Iran using Ollerenshaw's fascioliasis risk index incorporating geographical information system (GIS). Using this index, a risk map of fascioliasis outbreaks for the entire country was developed. We determined that the country can be divided into 4 fascioliasis outbreak risk categories. Class 1, in which the Mt value is less than 100, includes more than 0.91 of the country's area. The climate in this class is not conducive to fascioliasis outbreaks in any month. Dryness and low temperature in the wet season (December to April) are the key barriers against fascioliasis outbreaks in this class. The risk map developed based on climatic factors indicated that only 0.03 of the country's area, including Gilan province in the northern region of Iran, is highly suitable to fascioliasis outbreaks during September to January. The Mt value is greater than 500 in this class. Heavy rainfall in the summer and fall, especially in Rasht, Astara and Bandar Anzaly (≥ 1000 mm/year), creates more suitable breeding places for snail intermediate hosts. Copyright © 2015 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

NASA Contributions to the Development and Testing of Climate Indicators

NASA Astrophysics Data System (ADS)

Houser, P. R.; Leidner, A. K.; Tsaoussi, L.; Kaye, J. A.

2014-12-01

NASA is a major contributor the U.S. National Climate Assessment (NCA), a central component of the 2012-2022 U.S. Global Change Research Program's Strategic Plan. NASA supports a range of global climate and related environmental assessment activities through its data records, models, and model-produced data sets, as well as through involvement of agency personnel. These assessments provide important information on climate change and are used by policymakers, especially with the recent increased interest in climate vulnerability, impacts, and adaptation. Climate indicators provide a clear and concise way of communicating to the NCA audiences about not only status and trends of physical drivers of the climate system, but also the ecological and socioeconomic impacts, vulnerabilities, and responses to those drivers. NASA is enhancing its participation in future NCAs by encouraging the developing and testing of potential indicators that best address the needs expressed in the NCA indicator vision and that leverage NASA's capabilities. This presentation will highlight a suite of new climate indicators that draws significantly from NASA -produced data and/or modeling products, to support decisions related to impacts, adaptation, vulnerability, and mitigation associated with climate and global change.

Developing quantitative criteria to evaluate AOGCMs for application to regional climate assessments

NASA Astrophysics Data System (ADS)

Hayhoe, K.; Wake, C.; Bradbury, J.; Degaetano, A.; Hertel, A.

2006-12-01

Climate projections are the foundation for regional assessments of potential climate impacts. However, the soundness of regional assessments depends on the ability of global climate models to reproduce key processes responsible for regional climate trends. Here, we develop a systematic method to compare observed climate with historical atmosphere-ocean general circulation model (AOGCM) simulations, to assess the degree to which AOGCMs are able to reproduce regional circulation patterns. Applying this methodology to the U.S. Northeast (NE), we find that nearly all AOGCMs simulate a reasonable winter NAO pattern and seasonal positions of the Jet Stream and the East Coast Trough. However, not all models capture observed correlations between these circulation patterns and seasonal climate anomalies in the NE. Using only those AOGCMs that meet the criteria in each of these areas, we then develop projections of future climate change in the NE. The primary changes projected to occur over the next century - slightly greater temperature increases in summer than winter, and increases in winter precipitation - are consistent with projected trends in regional climate processes and are relatively independent of model or scale. These suggest confidence in the direction and potential range of the most notable regional climate trends, with the absolute magnitude of change depending on both the sensitivity of the climate system to human forcing as well as on human emissions over coming decades.

Climate Change Professional Development Approaches: Design Considerations, Teacher Enactment, and Student Learning

NASA Astrophysics Data System (ADS)

Drewes, A.; Henderson, J.; Mouza, C.

2017-12-01

Climate change is one of the most pressing challenges facing society, and climate change educational models are emerging in response. This study investigates the implementation and enactment of a climate change professional development model for science educators and its impact on student learning. Using an intrinsic case study methodology, we focused analytic attention on how one teacher made specific curricular, pedagogical, and content decisions, and the implications of those decisions for student's conceptual learning.The research presented here reports on the instructional design, pedagogical enactment, and subsequent effects on student learning of a climate change professional development (PD) model in the United States. Using anthropological theories of conceptual travel, we traced salient ideas from the PD through instructional delivery and into the evidence of student reasoning. We sought to address the following research questions: 1) How did a middle school teacher integrate climate change concepts into her science curriculum following PD participation? and 2) How did climate change instruction influence student understanding of key climate change constructs?From observation of the classroom instruction, we determined that the teacher effectively integrated new climate change information into her pre-existing schema. Additionally, through retrospective analysis of the PD, we found the design of the PD foregrounded the causes, mechanisms and likely effects of anthropogenic climate change at the expense of mitigation and adaptation strategies, and this differentially shaped how climate change was taught in the teacher's classroom. Analysis of student reasoning evidence showed that students gained an increased understanding of the enhanced greenhouse effect and the implications of human activity on this enhanced effect at statistically significant levels and with moderate effect sizes. However, students demonstrated a limited, though non-significant gain on

Untangling climate signals from autogenic changes in long-term peatland development

NASA Astrophysics Data System (ADS)

Morris, Paul J.; Baird, Andy J.; Young, Dylan M.; Swindles, Graeme T.

2015-12-01

Peatlands represent important archives of Holocene paleoclimatic information. However, autogenic processes may disconnect peatland hydrological behavior from climate and overwrite climatic signals in peat records. We use a simulation model of peatland development driven by a range of Holocene climate reconstructions to investigate climate signal preservation in peat records. Simulated water-table depths and peat decomposition profiles exhibit homeostatic recovery from prescribed changes in rainfall, whereas changes in temperature cause lasting alterations to peatland structure and function. Autogenic ecohydrological feedbacks provide both high- and low-pass filters for climatic information, particularly rainfall. Large-magnitude climatic changes of an intermediate temporal scale (i.e., multidecadal to centennial) are most readily preserved in our simulated peat records. Simulated decomposition signals are offset from the climatic changes that generate them due to a phenomenon known as secondary decomposition. Our study provides the mechanistic foundations for a framework to separate climatic and autogenic signals in peat records.

Potential distribution of dengue fever under scenarios of climate change and economic development.

PubMed

Aström, Christofer; Rocklöv, Joacim; Hales, Simon; Béguin, Andreas; Louis, Valerie; Sauerborn, Rainer

2012-12-01

Dengue fever is the most important viral vector-borne disease with ~50 million cases per year globally. Previous estimates of the potential effect of global climate change on the distribution of vector-borne disease have not incorporated the effect of socioeconomic factors, which may have biased the results. We describe an empirical model of the current geographic distribution of dengue, based on the independent effects of climate and gross domestic product per capita (GDPpc, a proxy for socioeconomic development). We use the model, along with scenario-based projections of future climate, economic development, and population, to estimate populations at risk of dengue in the year 2050. We find that both climate and GDPpc influence the distribution of dengue. If the global climate changes as projected but GDPpc remained constant, the population at risk of dengue is estimated to increase by about 0.28 billion in 2050. However, if both climate and GDPpc change as projected, we estimate a decrease of 0.12 billion in the population at risk of dengue in 2050. Empirically, the geographic distribution of dengue is strongly dependent on both climatic and socioeconomic variables. Under a scenario of constant GDPpc, global climate change results in a modest but important increase in the global population at risk of dengue. Under scenarios of high GDPpc, this adverse effect of climate change is counteracted by the beneficial effect of socioeconomic development.

Interactive Development of Regional Climate Web Pages for the Western United States

NASA Astrophysics Data System (ADS)

Oakley, N.; Redmond, K. T.

2013-12-01

Weather and climate have a pervasive and significant influence on the western United States, driving a demand for information that is ongoing and constantly increasing. In communications with stakeholders, policy makers, researchers, educators, and the public through formal and informal encounters, three standout challenges face users of weather and climate information in the West. First, the needed information is scattered about the web making it difficult or tedious to access. Second, information is too complex or requires too much background knowledge to be immediately applicable. Third, due to complex terrain, there is high spatial variability in weather, climate, and their associated impacts in the West, warranting information outlets with a region-specific focus. Two web sites, TahoeClim and the Great Basin Weather and Climate Dashboard were developed to overcome these challenges to meeting regional weather and climate information needs. TahoeClim focuses on the Lake Tahoe Basin, a region of critical environmental concern spanning the border of Nevada and California. TahoeClim arose out of the need for researchers, policy makers, and environmental organizations to have access to all available weather and climate information in one place. Additionally, TahoeClim developed tools to both interpret and visualize data for the Tahoe Basin with supporting instructional material. The Great Basin Weather and Climate Dashboard arose from discussions at an informal meeting about Nevada drought organized by the USDA Farm Service Agency. Stakeholders at this meeting expressed a need to take a 'quick glance' at various climate indicators to support their decision making process. Both sites were designed to provide 'one-stop shopping' for weather and climate information in their respective regions and to be intuitive and usable by a diverse audience. An interactive, 'co-development' approach was taken with sites to ensure needs of potential users were met. The sites were

Key Findings from the U.S.-India Partnership for Climate Resilience Workshop on Development and Application of Downscaling Climate Projections

NASA Astrophysics Data System (ADS)

Kunkel, K.; Dissen, J.; Easterling, D. R.; Kulkarni, A.; Akhtar, F. H.; Hayhoe, K.; Stoner, A. M. K.; Swaminathan, R.; Thrasher, B. L.

2017-12-01

s part of the Department of State U.S.-India Partnership for Climate Resilience (PCR), scientists from NOAA NCEI, CICS-NC, Texas Tech University (TTU), Stanford University (SU), and the Indian Institute of Tropical Meteorology (IITM) held a workshop at IITM in Pune, India during 7-9 March 2017 on the development, techniques and applications of downscaled climate projections. Workshop participants from TTU, SU, and IITM presented state-of-the-art climate downscaling techniques using the ARRM method, NASA NEX climate products, CORDEX-South Asia and analysis tools for resilience planning and sustainable development. PCR collaborators in attendance included Indian practitioners, researchers and other NGO including the WRI Partnership for Resilience and Preparedness (PREP), The Energy and Resources Institute (TERI), and NIH. The scientific techniques were provided to workshop participants in a software package written in R by TTU scientists and several sessions were devoted to hands-on experience with the software package. The workshop further examined case studies on the use of downscaled climate data for decision making in a range of sectors, including human health, agriculture, and water resources management as well as to inform the development of the India State Action Plans. This talk will discuss key outcomes including information needs for downscaling climate projections, importance of QA/QC of the data, key findings from select case studies, and the importance of collaborations and partnerships to apply downscaling projections to help inform the development of the India State Action Plans.

Registration of six germplasm lines of cotton, Gosspyium hirsutum L. with resistance to root-knot and reniform nematodes

USDA-ARS?s Scientific Manuscript database

Six Upland cotton, Gossypium hirsutum L., germplasm lines, M Rk-Rn 1, M Rk-Rn 2, M Rk-Rn 3, M Rk-Rn 4, M Rk-Rn 5, and M Rk-Rn 6, with resistance to root-knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood, and reniform nematode, Rotylenchulus reniformis Linford and Oliveria, were jointl...

77 FR 32572 - (NOAA) National Climate Assessment and Development Advisory Committee (NCADAC)

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-01

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration (NOAA) National Climate...: Notice of Open Meeting. SUMMARY: The National Climate Assessment and Development Advisory Committee... impacts of climate. Time and Date: The meeting will be held June 14, 2012 from 1:00 p.m. to 5:30 p.m. and...

Developing Health-Related Indicators of Climate Change: Australian Stakeholder Perspectives.

PubMed

Navi, Maryam; Hansen, Alana; Nitschke, Monika; Hanson-Easey, Scott; Pisaniello, Dino

2017-05-22

Climate-related health indicators are potentially useful for tracking and predicting the adverse public health effects of climate change, identifying vulnerable populations, and monitoring interventions. However, there is a need to understand stakeholders' perspectives on the identification, development, and utility of such indicators. A qualitative approach was used, comprising semi-structured interviews with key informants and service providers from government and non-government stakeholder organizations in South Australia. Stakeholders saw a need for indicators that could enable the monitoring of health impacts and time trends, vulnerability to climate change, and those which could also be used as communication tools. Four key criteria for utility were identified, namely robust and credible indicators, specificity, data availability, and being able to be spatially represented. The variability of risk factors in different regions, lack of resources, and data and methodological issues were identified as the main barriers to indicator development. This study demonstrates a high level of stakeholder awareness of the health impacts of climate change, and the need for indicators that can inform policy makers regarding interventions.

Development of ALARO-Climate regional climate model for a very high resolution

NASA Astrophysics Data System (ADS)

Skalak, Petr; Farda, Ales; Brozkova, Radmila; Masek, Jan

2014-05-01

ALARO-Climate is a new regional climate model (RCM) derived from the ALADIN LAM model family. It is based on the numerical weather prediction model ALARO and developed at the Czech Hydrometeorological Institute. The model is expected to able to work in the so called "grey zone" physics (horizontal resolution of 4 - 7 km) and at the same time retain its ability to be operated in resolutions in between 20 and 50 km, which are typical for contemporary generation of regional climate models. Here we present the main results of the RCM ALARO-Climate model simulations in 25 and 6.25 km resolutions on the longer time-scale (1961-1990). The model was driven by the ERA-40 re-analyses and run on the integration domain of ~ 2500 x 2500 km size covering the central Europe. The simulated model climate was compared with the gridded observation of air temperature (mean, maximum, minimum) and precipitation from the E-OBS version dataset 8. Other simulated parameters (e.g., cloudiness, radiation or components of water cycle) were compared to the ERA-40 re-analyses. The validation of the first ERA-40 simulation in both, 25 km and 6.25 km resolutions, revealed significant cold biases in all seasons and overestimation of precipitation in the selected Central Europe target area (0° - 30° eastern longitude ; 40° - 60° northern latitude). The differences between these simulations were small and thus revealed a robustness of the model's physical parameterization on the resolution change. The series of 25 km resolution simulations with several model adaptations was carried out to study their effect on the simulated properties of climate variables and thus possibly identify a source of major errors in the simulated climate. The current investigation suggests the main reason for biases is related to the model physic. Acknowledgements: This study was performed within the frame of projects ALARO (project P209/11/2405 sponsored by the Czech Science Foundation) and CzechGlobe Centre (CZ.1

The patient safety climate in healthcare organizations (PSCHO) survey: Short-form development.

PubMed

Benzer, Justin K; Meterko, Mark; Singer, Sara J

2017-08-01

Measures of safety climate are increasingly used to guide safety improvement initiatives. However, cost and respondent burden may limit the use of safety climate surveys. The purpose of this study was to develop a 15- to 20-item safety climate survey based on the Patient Safety Climate in Healthcare Organizations survey, a well-validated 38-item measure of safety climate. The Patient Safety Climate in Healthcare Organizations was administered to all senior managers, all physicians, and a 10% random sample of all other hospital personnel in 69 private sector hospitals and 30 Veterans Health Administration hospitals. Both samples were randomly divided into a derivation sample to identify a short-form subset and a confirmation sample to assess the psychometric properties of the proposed short form. The short form consists of 15 items represented 3 overarching domains in the long-form scale-organization, work unit, and interpersonal. The proposed short form efficiently captures 3 important sources of variance in safety climate: organizational, work-unit, and interpersonal. The short-form development process was a practical method that can be applied to other safety climate surveys. This safety climate short form may increase response rates in studies that involve busy clinicians or repeated measures. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Developing the architecture for the Climate Information Portal for Copernicus

NASA Astrophysics Data System (ADS)

Som de Cerff, Wim; Thijsse, Peter; Plieger, Maarten; Pascoe, Stephen; Jukes, Martin; Leadbetter, Adam; Goosen, Hasse; de Vreede, Ernst

2015-04-01

Climate change is impacting the environment, society and policy decisions. Information about climate change is available from many sources, but not all of them are reliable. The CLIPC project is developing a portal to provide a single point of access for authoritative scientific information on climate change. This ambitious objective is made possible through the Copernicus Earth Observation Programme for Europe, which will deliver a new generation of environmental measurements of climate quality. The data about the physical environment which is used to inform climate change policy and adaptation measures comes from several categories: satellite measurements, terrestrial observing systems, model projections and simulations and from re-analyses (syntheses of all available observations constrained with numerical weather prediction systems). These data categories are managed by different communities: CLIPC will provide a single point of access for the whole range of data. Information on data value and limitations will be provided as part of a knowledge base of authoritative climate information. The impacts of climate change on society will generally reflect a range of different environmental and climate system changes, and different sectors and actors within society will react differently to these changes. The CLIPC portal will provide some a number of indicators showing impacts on specific sectors which have been generated using a range of factors selected through structured expert consultation. It will also, as part of the transformation services, allow users to explore the consequences of using different combinations of driving factors which they consider to be of particular relevance to their work or life. The portal will provide information on the scientific quality and pitfalls of such transformations to prevent misleading usage of the results. The CLIPC project will not be able to process a comprehensive range of climate change impacts on the physical

The Climate Voices Speakers Network: Collaborating with Nontraditional, National Networks to Develop Climate Literacy on a Local Level

NASA Astrophysics Data System (ADS)

Wegner, K.; Schmidt, C.; Herrin, S.

2015-12-01

How can we leverage the successes of the numerous organizations in the climate change communication arena to build momentum rather than reinvent the wheel? Over the past two years, Climate Voices (climatevoices.org) has established a network of nearly 400 speakers and established partnerships to scale programs that address climate change communication and community engagement. In this presentation, we will present how we have identified and fostered win-win partnerships with organizations, such as GreenFaith Interfaith Partners for the Environment and Rotary International, to reach the broader general public. We will also share how, by drawing on the resources from the National Climate Assessment and the expertise of our own community, we developed and provided our speakers the tools to provide their audiences access to basic climate science - contributing to each audience's ability to understand local impacts, make informed decisions, and gain the confidence to engage in solutions-based actions in response to climate change. We will also discuss how we have created webinar coaching presentations by speakers who aren't climate scientists- and why we have chosen to do so.

Approaches for monitoring the release of Pochonia chlamydosporia var. catenulata, a biocontrol agent of root-knot nematodes.

PubMed

Atkins, Simon D; Hidalgo-Diaz, Leopoldo; Clark, Ian M; Morton, C Oliver; de Oca, Nivian Montes; Gray, Paul A; Kerry, Brian R

2003-02-01

Pochonia chlamydosporia var. catenulata is a potential biocontrol agent against root-knot nematodes. Diagnosis of isolates has relied on morphological identification, and is both time-consuming and difficult. beta-tubulin primers have been developed for the identification of this fungus that were specific enough to distinguish between varieties of the fungus within the same species. Separate primers have been developed for the specific detection of P. chlamydosporia var. catenulata based on ITS sequences, which were able to detect the fungus in soil from various sites in Cuba where the biocontrol agent had been added. When the PCR diagnosis was combined with serial dilution of soil samples on selective medium, colonies were rapidly identified. The fungus was still present, albeit at low densities, in soils inoculated five years previously. The development of a baiting method allowed quick in situ screening of the isolates' ability to infect nematode eggs, and when combined with PCR diagnosis both varieties of the fungus could be detected in infected eggs. RFLP analysis of ITS sequences from P. chlamydosporia provided an extra level of discrimination between isolates.

Root-Knot Nematodes Exhibit Strain-Specific Clumping Behavior That Is Inherited as a Simple Genetic Trait

PubMed Central

Wang, Congli; Lower, Steven; Thomas, Varghese P.; Williamson, Valerie M.

2010-01-01

Root-knot nematodes are obligate parasites of a wide range of plant species and can feed only on the cytoplasm of living plant cells. In the absence of a suitable plant host, infective juveniles of strain VW9 of the Northern root-knot nematode, Meloidogyne hapla, when dispersed in Pluronic F-127 gel, aggregate into tight, spherical clumps containing thousands of worms. Aggregation or clumping behavior has been observed in diverse genera in the phylum Nematoda spanning free-living species such as Caenorhabditis elegans as well as both plant and animal parasites. Clumping behavior differs between strains of M. hapla and occurs with other species within this genus where strain-specific differences in clumping ability are also apparent. Exposure of M. hapla juveniles to a gradient formed using low levels of cyanide promotes formation of clumps at a preferred cyanide level. Analysis of F2 lines from a cross of M. hapla strains that differ in clump-forming behavior reveals that the behavior segregates as a single, major locus that can be positioned on the genetic map of this nematode. Clumping behavior may be a survival strategy whose importance and function depend on the niche of the nematode strain or species. PMID:21151553

Education for Sustainable Development and Climate Change Education in China: A Status Report

ERIC Educational Resources Information Center

Han, Qingqing

2015-01-01

Recognizing the significance of education in promoting sustainable development (SD), China has developed a number of policies and initiatives relating to education for sustainable development (ESD) and climate change education (CCE). The article first reviews China's national policies and initiatives with regard to SD, climate change, education,…

Development of climate data storage and processing model

NASA Astrophysics Data System (ADS)

Okladnikov, I. G.; Gordov, E. P.; Titov, A. G.

2016-11-01

We present a storage and processing model for climate datasets elaborated in the framework of a virtual research environment (VRE) for climate and environmental monitoring and analysis of the impact of climate change on the socio-economic processes on local and regional scales. The model is based on a «shared nothings» distributed computing architecture and assumes using a computing network where each computing node is independent and selfsufficient. Each node holds a dedicated software for the processing and visualization of geospatial data providing programming interfaces to communicate with the other nodes. The nodes are interconnected by a local network or the Internet and exchange data and control instructions via SSH connections and web services. Geospatial data is represented by collections of netCDF files stored in a hierarchy of directories in the framework of a file system. To speed up data reading and processing, three approaches are proposed: a precalculation of intermediate products, a distribution of data across multiple storage systems (with or without redundancy), and caching and reuse of the previously obtained products. For a fast search and retrieval of the required data, according to the data storage and processing model, a metadata database is developed. It contains descriptions of the space-time features of the datasets available for processing, their locations, as well as descriptions and run options of the software components for data analysis and visualization. The model and the metadata database together will provide a reliable technological basis for development of a high- performance virtual research environment for climatic and environmental monitoring.

Global climate change implications for coastal and offshore oil and gas development

USGS Publications Warehouse

Burkett, V.

2011-01-01

The discussion and debate about climate change and oil and gas resource development has generally focused on how fossil fuel use affects the Earth's climate. This paper explores how the changing climate is likely to affect oil and gas operations in low-lying coastal areas and the outer continental shelf. Oil and gas production in these regions comprises a large sector of the economies of many energy producing nations. Six key climate change drivers in coastal and marine regions are characterized with respect to oil and gas development: changes in carbon dioxide levels and ocean acidity, air and water temperature, precipitation patterns, the rate of sea level rise, storm intensity, and wave regime. These key drivers have the potential to independently and cumulatively affect coastal and offshore oil and gas exploration, production, and transportation, and several impacts of climate change have already been observed in North America. ?? 2011.

78 FR 60023 - Endangered and Threatened Wildlife and Plants; Proposed Threatened Status for the Rufa Red Knot...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-30

...We, the U.S. Fish and Wildlife Service, propose to list the rufa red knot (Calidris canutus rufa) as a threatened species under the Endangered Species Act of 1973, as amended (Act). If we finalize this rule as proposed, it would extend the Act's protections to this species. The effect of this regulation will be to add this species to the List of Endangered and Threatened Wildlife.

77 FR 43574 - National Climate Assessment and Development Advisory Committee (NCADAC); Open Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-25

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration (NOAA) National Climate... NOAA National Climate Assessment and Development Advisory Committee (NCADAC). Time and Date: The... check the National Climate Assessment Web site for additional information at http://www.globalchange.gov...

Development of risk matrices for evaluating climatic change responses of forested habitats

Treesearch

Louis R. Iverson; Stephen N. Matthews; Anantha M. Prasad; Matthew P. Peters; Gary. Yohe

2012-01-01

We present an approach to assess and compare risk from climate change among multiple species through a risk matrix, in which managers can quickly prioritize for species that need to have strategies developed, evaluated further, or watched. We base the matrix upon earlier work towards the National Climate Assessment for potential damage to infrastructures from climate...

The Satellites, Weather and Climate (SWAC) Teacher Professional Development Program: Making the Case for Climate and Geospatial Literacy

ERIC Educational Resources Information Center

Dupigny-Giroux, Lesley-Ann; Toolin, Regina; Hogan, Stephen; Fortney, Michael D.

2012-01-01

In July 2008, a new professional development program called Satellites, Weather and Climate (SWAC) began at the University of Vermont. Its goal was to enhance the competency of in-service K-12 science and mathematics Vermont teachers in the atmospheric, climate, and geospatial sciences. The pilot program ran until 2010, during which time 14…

Exploring Climate Science with WV Educators: A Regional Model for Teacher Professional Development

NASA Astrophysics Data System (ADS)

Ruberg, L. F.; Calinger, M.

2014-12-01

The National Research Council Framework for K-12 Science Literacy reports that children reared in rural agricultural communities, who experience regular interactions with plants and animals, develop more sophisticated understanding of ecology and biological systems than do urban and suburban children of the same age. West Virginia (WV) is a rural state. The majority of its residents live in communities of fewer than 2,500 people. Based on the features of the population being served and their unique strengths, this presentation focuses on a regional model for teacher professional development that addresses agricultural and energy vulnerabilities and adaptations to climate change in WV. The professional development model outlined shows how to guide teachers to use a problem-based learning approach to introduce climate data and analysis techniques within a scenario context that is locally meaningful. This strategy engages student interest by focusing on regional and community concerns. Climate science standards are emphasized in the Next Generation Science Standards, but WV has not provided its teachers with appropriate instructional resources to meet those standards. The authors addressed this need by offering a series of climate science education workshops followed by online webinars offered to WV science educators free of charge with funding by the West Virginia Space Grant Consortium. The authors report on findings from this series of professional development workshops conducted in partnership with the West Virginia Science Teachers Association. The goal was to enhance grades 5-12 teaching and learning about climate change through problem-based learning. Prior to offering the climate workshops, all WV science educators were asked to complete a short questionnaire. As Figure 1 shows, over 40% of the teacher respondents reported being confident in teaching climate science content. For comparison post workshops surveys measure teacher confidence in climate science

Projected effects of climate and development on California wildfire emissions through 2100.

PubMed

Hurteau, Matthew D; Westerling, Anthony L; Wiedinmyer, Christine; Bryant, Benjamin P

2014-02-18

Changing climatic conditions are influencing large wildfire frequency, a globally widespread disturbance that affects both human and natural systems. Understanding how climate change, population growth, and development patterns will affect the area burned by and emissions from wildfires and how populations will in turn be exposed to emissions is critical for climate change adaptation and mitigation planning. We quantified the effects of a range of population growth and development patterns in California on emission projections from large wildfires under six future climate scenarios. Here we show that end-of-century wildfire emissions are projected to increase by 19-101% (median increase 56%) above the baseline period (1961-1990) in California for a medium-high temperature scenario, with the largest emissions increases concentrated in northern California. In contrast to other measures of wildfire impacts previously studied (e.g., structural loss), projected population growth and development patterns are unlikely to substantially influence the amount of projected statewide wildfire emissions. However, increases in wildfire emissions due to climate change may have detrimental impacts on air quality and, combined with a growing population, may result in increased population exposure to unhealthy air pollutants.

CRSI (Climate Resilience Screening Index) - Development and Application

EPA Science Inventory

We developed a Climate Resilience Screening Index that is applicable at multiple scales for the United States. Those scales include national, state, county and community. In order to explicitly include domains, indicators and metrics addressing environmental, economic and soci...

75 FR 81233 - National Climate Assessment Development and Advisory Committee; Establishment and Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-27

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Climate Assessment... Public Meeting. SUMMARY: This Notice advises of the public of the establishment of the National Climate... establishment of the National Climate Assessment Development and Advisory Committee (NCADAC) is in the public...

The DURAMAZ indicator system: a cross-disciplinary comparative tool for assessing ecological and social changes in the Amazon.

PubMed

Le Tourneau, François-Michel; Marchand, Guillaume; Greissing, Anna; Nasuti, Stéphanie; Droulers, Martine; Bursztyn, Marcel; Léna, Philippe; Dubreuil, Vincent

2013-06-05

During the last 20 years, the Amazon region has been at the same time a place of massive ecological and social change and a laboratory of experiments aimed at promoting sustainable development. Policies and project initiatives involving diverse social groups and environmental contexts have been implemented across the region. They have resulted in mixed outcomes and trade-offs between social and environmental dimensions, making their impact at the local level difficult to assess and their successes difficult to generalize. The objective of the DURAMAZ research project was to provide a better understanding of these impacts. It produced a multi-dimensional indicator system designed to allow a holistic view of sustainable development at local and subregional levels and a comparative perspective across 12 research sites, from an isolated indigenous village to smallholders and agribusiness areas in Mato Grosso. The results of the first observation campaign (2007-2009) show that despite the claim of promoting sustainable development, no project was able to untie the 'Gordian knot' of development in the Amazon. Communities continue to face the old dilemma of either enjoying a preserved ecosystem but enduring adverse life conditions, or enjoying better living at the expense of forest cover. Another finding is that the subregional context is very important in shaping the impacts of regional policies. Thus, the same policy will not always have the same effect, depending on in which context it is applied. Finally, we found that cultural factors and a sense of place play a more important role than economic factors when it comes to the way people evaluate their own situation. This research provides the basis for a second phase of the project (2012-2016) in which we will continue to expand our sample and to refine our methodologies with the goal of transforming the initiative into a network of observatories of sustainable development in the Amazon.

Development and initial validation of an Aviation Safety Climate Scale.

PubMed

Evans, Bronwyn; Glendon, A Ian; Creed, Peter A

2007-01-01

A need was identified for a consistent set of safety climate factors to provide a basis for aviation industry benchmarking. Six broad safety climate themes were identified from the literature and consultations with industry safety experts. Items representing each of the themes were prepared and administered to 940 Australian commercial pilots. Data from half of the sample (N=468) were used in an exploratory factor analysis that produced a 3-factor model of Management commitment and communication, Safety training and equipment, and Maintenance. A confirmatory factor analysis on the remaining half of the sample showed the 3-factor model to be an adequate fit to the data. The results of this study have produced a scale of safety climate for aviation that is both reliable and valid. This study developed a tool to assess the level of perceived safety climate, specifically of pilots, but may also, with minor modifications, be used to assess other groups' perceptions of safety climate.

Florida-focused climate change lesson demonstrations from the ASK Florida global and regional climate change professional development workshops

NASA Astrophysics Data System (ADS)

Weihs, R. R.

2013-12-01

A variety of Florida-focused climate change activities will be featured as part of the ASK Florida global and regional climate change professional development workshops. In a combined effort from Florida State University's Center for Ocean-Atmospheric Prediction Studies (COAPS) and University of South Florida's Coalition for Science Literacy (CSL), and supported by NASA's NICE initiative, the ASK Florida professional development workshops are a series of workshops designed to enhance and support climate change information and related pedagogical skills for middle school science teachers from Title-I schools in Florida. These workshops took place during a two-year period from 2011 to 2013 and consisted of two cohorts in Hillsborough and Volusia counties in Florida. Featured activities include lab-style exercises demonstrating topics such as storm surge and coastal geometry, sea level rise from thermal expansion, and the greenhouse effect. These types of labs are modified so that they allow more independent, inquiry thinking as they require teachers to design their own experiment in order to test a hypothesis. Lecture based activities are used to cover a broad range of topics including hurricanes, climate modeling, and sink holes. The more innovative activities are group activities that utilize roll-playing, technology and resources, and group discussion. For example, 'Climate Gallery Walk' is an activity that features group discussions on each of the climate literacy principles established by the United States Global Change Research Program. By observing discussions between individuals and groups, this activity helps the facilitators gather information on their previous knowledge and identify possible misconceptions that will be addressed within the workshops. Furthermore, 'Fact or Misconception' presents the challenge of identifying whether a given statement is fact or misconception based on the material covered throughout the workshops. It serves as a way to

Agent Model Development for Assessing Climate-Induced Geopolitical Instability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boslough, Mark B.; Backus, George A.

2005-12-01

We present the initial stages of development of new agent-based computational methods to generate and test hypotheses about linkages between environmental change and international instability. This report summarizes the first year's effort of an originally proposed three-year Laboratory Directed Research and Development (LDRD) project. The preliminary work focused on a set of simple agent-based models and benefited from lessons learned in previous related projects and case studies of human response to climate change and environmental scarcity. Our approach was to define a qualitative model using extremely simple cellular agent models akin to Lovelock's Daisyworld and Schelling's segregation model. Such modelsmore » do not require significant computing resources, and users can modify behavior rules to gain insights. One of the difficulties in agent-based modeling is finding the right balance between model simplicity and real-world representation. Our approach was to keep agent behaviors as simple as possible during the development stage (described herein) and to ground them with a realistic geospatial Earth system model in subsequent years. This work is directed toward incorporating projected climate data--including various C02 scenarios from the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report--and ultimately toward coupling a useful agent-based model to a general circulation model.3« less

Development of Distributed Research Center for analysis of regional climatic and environmental changes

NASA Astrophysics Data System (ADS)

Gordov, E.; Shiklomanov, A.; Okladnikov, I.; Prusevich, A.; Titov, A.

2016-11-01

We present an approach and first results of a collaborative project being carried out by a joint team of researchers from the Institute of Monitoring of Climatic and Ecological Systems, Russia and Earth Systems Research Center UNH, USA. Its main objective is development of a hardware and software platform prototype of a Distributed Research Center (DRC) for monitoring and projecting of regional climatic and environmental changes in the Northern extratropical areas. The DRC should provide the specialists working in climate related sciences and decision-makers with accurate and detailed climatic characteristics for the selected area and reliable and affordable tools for their in-depth statistical analysis and studies of the effects of climate change. Within the framework of the project, new approaches to cloud processing and analysis of large geospatial datasets (big geospatial data) inherent to climate change studies are developed and deployed on technical platforms of both institutions. We discuss here the state of the art in this domain, describe web based information-computational systems developed by the partners, justify the methods chosen to reach the project goal, and briefly list the results obtained so far.

Effects of Climate Change and Urban Development on Army Training Capabilities: Firing Ranges and Maneuver Areas