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Knots
Kinds of Knots Selected AbstractsA non-mathematical introduction to the superspace description of modulated structuresACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2009Trixie Wagner The X-ray analysis of (6R,7aS)-6-(tert -butyl-dimethylsilanyloxy)-1-hydroxy-2-phenyl-5,6,7,7a-tetrahydropyrrolizin-3-one, C19H27NO3Si, revealed a diffraction pattern which is typical for modulated structures: strong Bragg peaks surrounded by weaker reflections which cannot be indexed with the same three reciprocal lattice vectors that are used to describe the strong peaks. For this class of crystal structures the concept of superspace has been developed which, however, for many crystallographers still constitutes a Gordian Knot. As a possible tool to cut this knot the crystal structure of the above-mentioned tetrahydropyrrolizinone derivative is presented as an illustrative example for handling and describing the modulated structure of a typical pharmaceutical (i.e. molecular) compound. Having established a working knowledge of the concepts and terminology of the superspace approach a concise and detailed description of the complete process of peak indexing, data processing, structure solution and structure interpretation is presented for the incommensurately modulated crystal structure of the above-mentioned compound. The superspace symmetry applied is P21(,0,)0; the (incommensurate) q vector components at 100,K are , = 0.1422,(2) and , = 0.3839,(8). [source] 1, 2, 3, 4: Four Techniques to Secure Buried KnotsDERMATOLOGIC SURGERY, Issue 7 2002Daniel A. Davis MD background. High tension wounds can be difficult to close. objective. To enumerate methods for securing a surgeon's knot when tying buried sutures under tension. conclusion. The tension tranfer stitch is a swift and elegant method to secure surgeon's knots. [source] Differential mortality of wintering shorebirds on the Banc d'Arguin, Mauritania, due to predation by large falconsIBIS, Issue 2008PIET J. VAN DEN HOUT Predators may influence many aspects of the daily life and seasonal movements of their prey. Here we quantify direct, and evaluate indirect effects of predation by three falcon species (Lanner Falcon Falco biarmicus, Barbary Falcon Falco pelegrinoides and Peregrine Falcon Falco peregrinus) on coastal shorebirds wintering on the Banc d'Arguin, Mauritania, an area hosting approximately 30% of the East Atlantic Flyway population of shorebirds. On the basis of 754 h of observation over five winters, 97 witnessed attacks and 585 collected prey remains, we show that shorebirds were safer in larger flocks, which tended to be attacked less often. Furthermore, species that forage relatively close to shore and in small flocks were depredated more often than expected from their relative abundance. In three species, Red Knot Calidris canutus canutus, Bar-tailed Godwit Limosa lapponica taymyrensis and Dunlin Calidris alpina, the juveniles were more vulnerable than adults. We estimated that on average 1% of the juvenile and 0.1% of the adult Red Knots present were killed by large falcons each winter. For Red Knots we simultaneously quantified annual survival on the basis of an individual colour-marking programme: mortality due to predation by falcons accounted for an estimated 6.2% (juveniles) and 0.8% (adults) of annual mortality. We suggest that juvenile Red Knots are 10 times as likely to be killed by falcons because they use riskier habitats, i.e. early and late tide foraging areas closer to shores where surprise attacks are both more common and more successful. These results indicate that the strength of indirect effects of predation operating in a shorebird population largely outweigh the effects of mortality per se. [source] Selection of locations of knots for linear splines in random regression test-day modelsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2010J. Jamrozik Summary Using spline functions (segmented polynomials) in regression models requires the knowledge of the location of the knots. Knots are the points at which independent linear segments are connected. Optimal positions of knots for linear splines of different orders were determined in this study for different scenarios, using existing estimates of covariance functions and an optimization algorithm. The traits considered were test-day milk, fat and protein yields, and somatic cell score (SCS) in the first three lactations of Canadian Holsteins. Two ranges of days in milk (from 5 to 305 and from 5 to 365) were taken into account. In addition, four different populations of Holstein cows, from Australia, Canada, Italy and New Zealand, were examined with respect to first lactation (305 days) milk only. The estimates of genetic and permanent environmental covariance functions were based on single- and multiple-trait test-day models, with Legendre polynomials of order 4 as random regressions. A differential evolution algorithm was applied to find the best location of knots for splines of orders 4 to 7 and the criterion for optimization was the goodness-of-fit of the spline covariance function. Results indicated that the optimal position of knots for linear splines differed between genetic and permanent environmental effects, as well as between traits and lactations. Different populations also exhibited different patterns of optimal knot locations. With linear splines, different positions of knots should therefore be used for different effects and traits in random regression test-day models when analysing milk production traits. [source] Use of wetlands at the mouth of the Yangtze River by shorebirds during spring and fall migrationJOURNAL OF FIELD ORNITHOLOGY, Issue 4 2006Zhen-Ming Ge ABSTRACT The mouth of the Yangtze River is an important stopover site for migratory shorebirds using the East Asian-Australasian Flyway. From 1984 to 2004, we censused and banded shorebirds and monitored hunting activities at the mouth of the Yangtze River to understand how shorebirds used the study area. Counts and banding data revealed greater numbers of shorebirds at the mouth of the Yangtze River during northward migration (spring) than during southward migration (fall), with ratios varying from 1.5:1 to 7.2:1 at different sites from 1984 to 2005. The most common species observed during spring (northward) migration were Great Knots (Calidris tenuirostris), Red Knots (Calidris canutus), Bar-tailed Godwits (Limosa lapponica), Sharp-tailed Sandpipers (Calidris acuminata), and Red-necked Stints (Calidris ruficollis). During spring 2003,2004, 96.98% of the shorebirds observed were adults (ASY or older) and 3% were after hatching-year and second-year birds (AHY or SY). In contrast, almost all (94.73%) birds counted during the fall were hatching-year (HY) birds. These results indicate that adult shorebirds either use a different migration route during fall migration or use the same route, but do not stop at the mouth of the Yangtze River. HY birds, however, may depend on the coastal stopover sites for feeding during their first southward passage. SINOPSIS La desembocadura del Rio Yangtze es un importante punto de parada de playeros migratorios que utilizan la vía del Este-Asiático-Australásico. De 1984 to 2004 anillamos playeros y se condujeron censos para monitorear las actividades de cacería en la desembocadura del Yangtze y ademásdeterminar como los playeros utilizaban dicha área. Los conteos de aves anilladas revelaron un mayor número de playeros durante la migración hacia el norte (primaveral) que durante la migración hacia el sur (otoñal) con una tasa de 1.5:1 a 7.2:1 en diferentes localidades. Las especies que se observaron con mayor frecuencia durante la primavera (moviéndose hacia el norte) fueron Calidris tenuirostris, C. canutus, C. acuminata, C. ruficollis y Limosa lapponica. Durante la primavera del 2003,2004, el 96.98% de las aves observadas fueron adultos y el 3% fueron aves de segundo año o juveniles del primer año. En contraste el 94.73% de las aves contabilizadas durante el otoño fueron juveniles del primer año. Estos resultados indican que los adultos utilizan otra ruta durante la migración otoñal o una ruta similar pero que no paran en la desembocadura del Yangtze. Sin embargo, las aves de primer año muy bien pudieran depender de los recursos alimentarios de los puntos de parada costaneros durante su primer viaje hacia el sur. [source] Knot-Tying Habits, Tier Handedness, and Experience,JOURNAL OF FORENSIC SCIENCES, Issue 5 2010Robert C. Chisnall M.Ed. Abstract:, Previous research concerning tier handedness, experience and the configuration of simple, habitual knots has been scant and conflicting. Survey data were collected from 21 disparate groups comprising 562 respondents in total. Regardless of experience, respondents tied both Granny and Reef Knots. Dextral tying was dominated by S knots. Left-handers tied Z knots more frequently than right-handers. However, the frequency of S and Z knots relative to tier hand dominance, which is not binary, occurred on a continuum. Averaging all survey tasks, more than 70% of knots tied by dextrals were S, whereas only 56% of those tied by sinistrals were S. These percentages varied somewhat according to specific tying tasks and the number of working ends. Furthermore, tiers' shoelace and parcel knots were not always identical, and a ranked pattern in parcel and shoelace knots was revealed. The examination of habitual knots could benefit criminal investigations. [source] On-site Raman analysis of Iznik pottery glazes and pigmentsJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2004Philippe Colomban Abstract On-site Raman analyses were performed at the Musée National de Céramique, Sèvres, France, on rare Iznik (former Nicaea) pottery produced from ,1480 to ,1620. A comparison was made with a series of shards. The town of production of these potteries was highly disputed in the 1980s and many questions still remain. The potential of glaze on-site analyses as a classification/dating tool was evaluated. The structure of the silicate glaze does not change with the sample (index of polymerization ,0.5,0.8, indicating a lead silicate composition); characteristic SiO stretching mode doublet at ,985 and 1030,1050 cm,1. By contrast, the corresponding signature of most of the ,Kütahya' wares peaks at ,1070,1090 cm,1. The lowest index is measured for a brilliant overglazed red bole, according to a lower temperature of (post)firing. The different crystalline phases identified in the glaze are ,-quartz, haematite, spinel, cassiterite, uvarovite garnet and zircon. White colour arises from ,-quartz slip in most samples studied. Cassiterite (SnO2) opacifier is only present in some early blue-and-white ceramics (Master of the Knots and Baba Nakkas style, ,1510,1530) and we do not have other evidence of its intentional use as an opacifier. Intentional addition of tin oxide is likely for colour lightening in some red, blue and in clear green boles. At least two types of red glazes and two types of Cr-containing green pigments are evidenced. Copyright © 2004 John Wiley & Sons, Ltd. [source] Amide-Based Molecular Knots as Platforms for Fluorescent SwitchesCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2006Paolo Passaniti Dr. Abstract A series of amide-based molecular knots equipped selectively with fluorescent dansyl and/or pyrenesulfonyl moieties were synthesized from the readily available tris(allyloxy)knotane. UV/Vis absorption spectra, emission spectra, and the emission lifetimes of the fluorescent knotanes were investigated in chloroform at 298 K. The absorption spectra of the knotanes correspond to those of mixtures of their UV-active constituents. The fluorescence quantum yields and lifetimes of the dansyl and pyrenesulfonyl moieties are partly quenched by the knotane platform. In the KN(Da)2(Py) species, the fluorescent excited state of the dansyl units (,max=510 nm) lies at lower energy than the fluorescent excited state of the pyrenesulfonyl unit (,max=385 nm), the emission of which is accordingly quenched with sensitization of the dansyl fluorescence. In the KN(Ao)2(Da), KN(Ao)(Da)2, and KN(Da)3 species, the addition of acids causes the protonation of their dansyl units with a consequent decrease in the intensity of the dansyl band at 510 nm and appearance of the emission band of the protonated dansyl unit (,max=340 nm). Each dansyl unit of KN(Ao)(Da)2 and KN(Da)3 undergoes the independent protonation. In these incompletely protonated knotanes the fluorescence of the protonated dansyl units is partly quenched by nonprotonated ones. These processes can be quantitatively reversed upon addition of a base. In KN(Da)2(Py), an increase of the fluorescence of its pyrenesulfonyl group is observed when the dansyl groups are protonated. The results obtained show that the readily available and easily functionalizable amide-knotanes can be used as an interesting scaffold to obtain fluorescent switches. [source] Topologically Chiral Covalent Assemblies of Molecular Knots with Linear, Branched, and Cyclic ArchitecturesCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2004Oleg Lukin Dr. Abstract Selectively functionalized molecular knots (knotanes) of the amide-type have been used as building blocks in syntheses of higher covalent assemblies composed of up to four knotane units. Preparation of linear and branched tetraknotanes consisted of the consecutive selective removal of allyl groups followed by linking of the intermediate hydroxyknotanes with biphenyl-4,4,-disulfonyl chloride. Macrocyclic knotane oligomers involving two, three, and four knotane moieties were obtained by high-dilution cyclization of dihydroxyknotane and biphenyl-4,4,-disulfonyl chloride. Due to their relation with cyclophanes, the latter class of oligomeric knotanes was termed "knotanophanes". Chiral resolution analysis of new oligoknotanes has been attempted on chemically bonded Chiralpak AD stationary phases, however met severe difficulties due to their complex isomeric compositions, and in most cases a significant overlap of the isomer fractions was observed. In spite of the limits of presently available chiral stationary phases that allowed only partial resolution of the synthesized topologies, oligoknotanes have been shown to be of high fundamental interest due to their unprecedented chirality. The chirality descriptions of topologically chiral unsymmetrical dumbbell 4, and the linear tetraknotane 5 are analogous to the Fischer projections of erythrose/threose and hexaric acid, respectively, while the isomeric composition of the branched tetraknotane 8 is completely unique. Moreover, the linear and branched tetraknotanes are constitutional isomers. Chirality of knotanophanes represents, in turn, analogies to known cyclic forms of peptides or sugars with multiple stereogenic centers. [source] 1, 2, 3, 4: Four Techniques to Secure Buried KnotsDERMATOLOGIC SURGERY, Issue 7 2002Daniel A. Davis MD background. High tension wounds can be difficult to close. objective. To enumerate methods for securing a surgeon's knot when tying buried sutures under tension. conclusion. The tension tranfer stitch is a swift and elegant method to secure surgeon's knots. [source] Double Butterfly Suture for High Tension: A Broadly Anchored, Horizontal, Buried Interrupted SutureDERMATOLOGIC SURGERY, Issue 3 2000Helmut Breuninger MD Background. The excision of skin lesions such as tumors, nevi, and scars frequently results in tension on surgical wound margins. This tension is commonly counteracted surgically with buried, intracutaneous, interrupted sutures of absorbable material which are anchored vertically in the corium. Method. The horizontal, buried, intracutaneous butterfly suture has been described elsewhere. It is firmly anchored in the corium, everts wound margins, and adapts them nearly as broadly as two vertical sutures. It can also be laid as a double butterfly suture, as described here, and then has the shape of an "8." This double butterfly suture is equivalent to three vertical sutures because of its broad base in the corium. Moreover, it can cope with much greater tension because of its "pulley" effect. A single double butterfly suture usually suffices for small defects, particularly when the wound edges are cut obliquely with a longer rim of epidermis. Materials. We have laid the traditional butterfly suture in more than 35,000 skin lesion excisions since 1985 and the double butterfly suture alone or as a supplement in more than 10,000 sutures since 1992. We use 2-0 to 6-0 polydioxanone for these procedures, since it has proven in trials to be the best-absorbed suture material. Results. In most cases, the resulting scars were narrow and smooth in spite of high tension. Results were unsatisfactory in only 6.2% of procedures. Conclusion. The double butterfly suture described here has the advantages of withstanding tension better while everting wound margins and requiring fewer stitches for wound closure. However, it is important that the suture knot be deeply anchored beneath the corium. [source] The Knot of Contracts: The Corporate Geography of Legacy CostsECONOMIC GEOGRAPHY, Issue 2 2008Ashby H. B. Monk Abstract Burdensome past commitments are threatening a concentrated group of industries and communities, predominantly in the U.S. Midwest. Beginning with the bankruptcy of Delphi Corporation, this article documents the crisis for "old-economy firms" with significant legacy costs. To understand the root causes of this legacy crisis, the analysis builds on previous research in economic geography and the results of a widely subscribed and unique "expert opinion" survey highlighting the corporate impacts of defined benefit pensions in the private sector. The result is a conceptual framework that describes the corporate geography of legacy costs: the "knot of contracts." Specifically, the knot of contracts conceptualizes the role of intergenerational commitments in restricting corporate evolution and innovation, while underscoring time as a central component of the nature of the firm. Developing this framework requires linking microeconomic theories of the firm with the institutional aspects of firms' geographies. While referring to specific cases and proprietary data throughout, the article is principally concerned with understanding legacy costs. In addition, the intent is to uncover managerial and governmental behavior that tightened this knot of contracts and to expose the current managers' attempts to manage their firms through the adverse affects of the knot of contracts. The explanations in this article serve as a useful bridge between the realities faced by firms and their surrounding communities and the more abstract notions of the firm and competitiveness in the context of globalization. [source] The taming of the shrew milk teethEVOLUTION AND DEVELOPMENT, Issue 4 2008Elina Järvinen SUMMARY A characteristic feature of mammalian dentition is the evolutionary reduction of tooth number and replacement. Because mice do not replace teeth, here we used Sorex araneus, the common shrew, as a model to investigate the loss of tooth replacement. Historically, shrews have been reported to initiate the development of several, milk or deciduous teeth but these soon become rudimentary and only the replacement teeth erupt. Shrews thus offer a living example of a derived mammalian pattern where the deciduous tooth development is being suppressed. Based on histological and gene expression analyses of serial sections, we suggest that S. araneus has discernible tooth replacement only in the premolar 4 (P4) position. Both generations of teeth express Shh in the enamel knot and in the inner enamel epithelium. Nevertheless, the deciduous P4 (dP4) is reduced in size during embryogenesis and is eventually lost without becoming functional. Analysis of growth shows that P4 replaces the dP4 in a "double-wedge" pattern indicative of competitive replacement where the suppression of the deciduous tooth coincides with the initiation of its replacement. Because activator,inhibitor mechanisms have been implicated in adjacent mouse molars and in transgenic mice with continuous tooth budding, we suggest that evolutionary suppression of deciduous teeth may involve early activation of replacement teeth, which in turn begin to suppress their deciduous predecessors. [source] Functional role of B,-chain N-terminal fragment in the fibrin polymerization processFEBS JOURNAL, Issue 17 2007E. V. Lugovskoy Four mAbs of the IgG1 class to the thrombin-treated N-terminal disulfide knot of fibrin, secreted by various hybridomas, have been selected. Epitopes for two mAbs, I-3C and III-10d, were situated in human fibrin fragment B,15,26, and those for two other mAbs, I-5G and I-3B, were in fragment B,26,36. Three of these mAbs, I-5G, I-3B and III-10D, as well as their Fab-fragments, decreased the maximum rate of fibrin desAA and desAABB polymerization up to 90,95% at a molar ratio of mAb (or Fab-fragment) to fibrin of 1 or 2. The fourth mAb, I-3C, did not influence the fibrin desAABB polymerization and inhibited by 50% the maximum rate of fibrin desAA polymerization. These results suggest that these mAb inhibitors block a longitudinal fibrin polymerization site. As the mAbs retard both fibrin desAABB and fibrin desAA polymerization, one can conclude that the polymerization site does not coincide with polymerization site ,B' (B,15,17). To verify this suggestion, the polymerization inhibitory activity of synthetic peptides B,SARGHRPLDKKREEA(12,26), B,LDKKREEA(19,26), B,APSLRPAPPPI(26,36), B,APSLRPAPPPISGGGYRARPA(26,46) and B,GYRARPA(40,46), which imitate the various sequences in the N-terminal region of the fibrin B,-chain, have been investigated. Peptides B,12,26 and B,26,46, but not B,40,46, B,19,26, and B,26,36, proved to be specific inhibitors of fibrin polymerization. The IC50 values for B,12,26 and B,26,46 were 2.03 × 10,4 and 2.19 × 10,4 m, respectively. Turbidity and electron microscopy data showed that peptides B,12,26 and B,26,46 inhibited the fibrin protofibril formation stage of fibrin polymerization. The conclusion was drawn that fibrin fragment B,12,46 took part in fibrin protofibril formation simultaneously with site ,A' (A,17,19) prior to removal of fibrinopeptide B. A model of the intermolecular connection between fragment B,12,46 of one fibrin desAA molecule and the D-domain of another has been constructed. [source] Shorebird predation of horseshoe crab eggs in Delaware Bay: species contrasts and availability constraintsJOURNAL OF ANIMAL ECOLOGY, Issue 3 2007S. GILLINGS Summary 1Functional responses , the relationship between resource intake rate and resource abundance , are widely used in explaining predator,prey interactions yet many studies indicate that resource availability is crucial in dictating intake rates. 2For time-stressed migrant birds refuelling at passage sites, correct decisions concerning patch use are crucial as they determine fattening rates and an individual's future survival and reproduction. Measuring availability alongside abundance is essential if spatial and temporal patterns of foraging are to be explained. 3A suite of shorebird species stage in Delaware Bay where they consume horseshoe crab Limulus polyphemus eggs. Several factors including spawning activity and weather give rise to marked spatial and temporal variation in the abundance and availability of eggs. We undertook field experiments to determine and contrast the intake rates of shorebird species pecking for surface and probing for buried eggs. 4Whether eggs were presented on the sand surface or buried, we demonstrate strong aggregative responses and rapid depletion (up to 80%). Depletion was greater at deeper depths when more eggs were present. No consistent give-up densities were found. Type II functional responses were found for surface eggs and buried eggs, with peck success twice as high in the former. Maximum intake rates of surface eggs were up to 83% higher than those of buried eggs. 5Caution is needed when applying functional responses predicted on the basis of morphology. Our expectation of a positive relationship between body size and intake rate was not fully supported. The smallest species, semipalmated sandpiper, had the lowest intake rate but the largest species, red knot, achieved only the same intake rate as the mid-sized dunlin. 6These functional responses indicate that probing is rarely more profitable than pecking. Currently, few beaches provide egg densities sufficient for efficient probing. Areas where eggs are deposited on the sand surface are critical for successful foraging and ongoing migration. This may be especially true for red knot, which have higher energetic demands owing to their larger body size yet appear to have depressed intake rates because they consume smaller prey than their body size should permit. [source] Current trends in the structure,activity relationship studies of the endogenous agouti-related protein (AGRP) melanocortin receptor antagonistMEDICINAL RESEARCH REVIEWS, Issue 5 2005Andrzej M. Wilczynski Abstract Agouti-related protein (AGRP) is an endogenous antagonist of the melanocortin-3 and -4 (MC3R and MC4) G-protein coupled receptors. The 87,132 amino acid C-terminal domain of hAGRP possesses five disulfide bridges and a well-defined three-dimensional structure that displays full biological activity as compared to the full-length protein. Based on the NMR structure of the C-terminal AGRP(87,132), a novel mini-protein, referred to as "Mini-AGRP" was designed that exhibited receptor binding affinity and antagonism similar to that of the parent hAGRP(87,132) protein. It was demonstrated that this new-engineered protein autonomously folds to the inhibitor cystine knot (ICK) motif. As this AGRP is a novel mammalian protein involved in energy homeostasis and possibly other physiological functions remaining to be identified, structure-function studies are starting to emerge toward the understanding of how this unique protein putatively interacts with the melanocortin receptors with the objective of designing potential therapeutic agents for in vivo physiological studies. This article summarizes the progress to date of AGRP-based structure,activity relationships and putative ligand,receptor interactions. © 2005 Wiley Periodicals, Inc. [source] Learning microsurgical suturing and knotting techniques: comparative dataMICROSURGERY, Issue 1 2006D.Sc., Istvan Furka M.D., Ph.D. Correctly performed surgical sutures are the basis of surgical safety. This retrospective survey was conducted among participants (n = 263) taking graduate and postgraduate courses between 2000,2004. Placement of sutures, time to perform knotting, safety of knots, and quality of knot stability were tested. None of the students had been previously instructed in microsurgical techniques. At the beginning of the training program, 90,95% of participants damaged the suturing thread at several places. By the end of the course, knotting times significantly decreased in both groups. Graduates decreased their time from 6.8 ± 2.34 min to 3.28 ± 0.71 min (mean ± standard error of the mean), and postgraduates decreased their time from 5.02 ± 3.25 min to 1.54 ± 0.54 min (mean ± standard error of the mean). In our opinion, "mass training" to teach the basics of microsurgery is not a good approach. Instead, individual training should be provided, as tutors offer invaluable advice, and adjust almost each stitch and knot during teaching sessions. © 2006 Wiley-Liss, Inc. Microsurgery 26: 4,7, 2006. [source] Space very long baseline interferometry observations of polarization in the jet of 3C 380MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006A. Papageorgiou ABSTRACT A comparison between low-frequency space very long baseline interferometry (VLBI) and high-frequency ground-based VLBI images can, in principle, be used to detect small variations in rotation measure (RM) on fine angular scales inaccessible to ground arrays alone. This paper reports an attempt to perform such a comparison using the jet in the quasar 3C 380. Observations made with the VSOP antenna HALCA together with a ground array at wavelength 1.6 GHz provide total intensity and polarization images of comparable resolution to those from the ground array alone at 5 GHz. The results provide an image showing derotated magnetic vector position angle of somewhat higher resolution than that available earlier. The results show variations in an RM around component A of the order of 10 rad m,2 that could not have been detected with the ground array alone. It is concluded that satellite VLBI observations provide a promising means to study the distribution of matter and magnetic fields around parsec-scale jets. The ground observations used here follow the steady outward drift of component A, which has approximately doubled its distance from the core since the first observations in 1982. They also reveal total intensity and polarization structure associated with a bright knot 0.7 arcsec from the core which is reminiscent of that expected for a conical shock wave. [source] X-ray synchrotron emission from the oblique shock in the jet of the powerful radio galaxy 3C 346MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005D. M. Worrall ABSTRACT We report the first detection, with Chandra, of X-ray emission from the jet of the powerful narrow-line radio galaxy 3C 346. X-rays are detected from the bright radio and optical knot at which the jet apparently bends by approximately 70°. The Chandra observation also reveals a bright galaxy-scale atmosphere within the previously known cluster and provides a good X-ray spectrum for the bright core of 3C 346. The X-ray emission from the knot is synchrotron radiation, as seen in lower-power sources. In common with these sources, there is evidence of morphological differences between the radio/optical and X-ray structures, and the spectrum is inconsistent with a one-component continuous-injection model. We suggest that the X-ray-bright knot is associated with a strong oblique shock in a moderately relativistic, light jet, at , 20° to the line of sight, and that this shock is caused by the jet interacting with the wake in the cluster medium behind the companion galaxy of 3C 346. The general jet curvature can result from pressure gradients in the cluster atmosphere. [source] CD 95 mediated apoptosis in embryogenesis: implication in tooth developmentORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 3 2006E Matalová Structured abstract Authors,,, Matalová E, ,etková J, Blackburn J, Mí,ek I, Sharpe PT Introduction,,, Understanding of apoptotic mechanisms involved in tissue shaping is of particular interest because of possible targeted modulation of the development of organ structures such as teeth. Research of CD 95 mediated apoptosis has been focused particularly on cell death in the immune system and related disorders. However, CD 95 mediated apoptosis is also involved in embryogenesis of many organs as the kidney, the lung, the intestine and tissue networks such as the nervous system. Design,,, Narrative review. Results,,, This review briefly summarizes the current knowledge of CD 95 mediated apoptosis in embryogenesis with possible implication in tooth development. CD 95 receptor and CD 95 ligand are found at early stages of tooth development. The data suggest some positive correlations with dental apoptosis distribution, particularly in the primary enamel knot where apoptosis occurs during elimination of this structure. CD 95 deficient (lpr) adult mouse tooth phenotype, however, did not show any alterations in final tooth pattern and morphology. Conclusion,,, To date studies of apoptotic machinery during tooth development show spatial localization of many of the components together with precise and localized timing of cell death. There is still much to be learned about the regulation and importance of apoptosis in tooth development. Nevertheless, the involvement of apoptotic regulatory mechanisms interplaying with other molecules participates to the cellular cross-talk in developing tissues, which opens possible targeted modulations as suggested, e.g. for future molecular dentistry. [source] Evaluation of body mass index, pre-vaccination serum progesterone levels and anti-anthrax protective antigen immunoglobulin G on injection site adverse events following anthrax vaccination in womenPHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 11 2008Yujia Zhang PhD Abstract Background In 2002, CDC initiated the Anthrax Vaccination Program (AVP) to provide voluntary pre-exposure anthrax vaccination for individuals at high risk for exposure to Bacillus anthracis spores. The AVP offered an opportunity to investigate hypothesized reasons for a reported gender difference in injection site adverse events (AEs) following anthrax vaccine adsorbed (AVA). Objectives To evaluate in women the impact of body mass index (BMI), pre-vaccination serum progesterone levels, and pre-vaccination anti-anthrax protective antigen immunoglobulin G concentrations (anti-PA IgG) on the occurrence of AEs following subcutaneous AVA vaccination. Methods Participants' BMI was determined at enrollment. Also, pre-vaccination blood samples were assayed for serum progesterone and anti-PA IgG. Post-vaccination solicited AEs were recorded by participants using a 4-day diary card. Results Obese group had an elevated risk for arm soreness. Decreased pre-vaccination serum progesterone level was associated with arm swelling. Increased pre-vaccination anti-PA IgG was associated with itching on the arm; and within the obese group, was associated with arm swelling, lump or knot, redness, soreness, and warmth. Conclusions In AVA vaccinated women, obesity was associated with arm soreness and decreased pre-vaccination serum progesterone levels were associated with increased rate of arm swelling. Increased pre-vaccination anti-PA IgG may be associated with an increased frequency of itching on the arm, and in obese women, may increase the occurrence of arm swelling, lump or knot, redness, and warmth. Administering AVA according to a woman's menstrual phase may reduce the occurrence of certain injection site reactions. Copyright © 2008 John Wiley & Sons, Ltd. [source] A non-mathematical introduction to the superspace description of modulated structuresACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2009Trixie Wagner The X-ray analysis of (6R,7aS)-6-(tert -butyl-dimethylsilanyloxy)-1-hydroxy-2-phenyl-5,6,7,7a-tetrahydropyrrolizin-3-one, C19H27NO3Si, revealed a diffraction pattern which is typical for modulated structures: strong Bragg peaks surrounded by weaker reflections which cannot be indexed with the same three reciprocal lattice vectors that are used to describe the strong peaks. For this class of crystal structures the concept of superspace has been developed which, however, for many crystallographers still constitutes a Gordian Knot. As a possible tool to cut this knot the crystal structure of the above-mentioned tetrahydropyrrolizinone derivative is presented as an illustrative example for handling and describing the modulated structure of a typical pharmaceutical (i.e. molecular) compound. Having established a working knowledge of the concepts and terminology of the superspace approach a concise and detailed description of the complete process of peak indexing, data processing, structure solution and structure interpretation is presented for the incommensurately modulated crystal structure of the above-mentioned compound. The superspace symmetry applied is P21(,0,)0; the (incommensurate) q vector components at 100,K are , = 0.1422,(2) and , = 0.3839,(8). [source] Simple, instrument-assisted technique for tying a slip knot: a note of cautionANZ JOURNAL OF SURGERY, Issue 4 2004Jacob W. T. Ng No abstract is available for this article. [source] DEADLOCK AVOIDANCE FOR FLEXIBLE MANUFACTURING SYSTEMS WITH CHOICES BASED ON DIGRAPH CIRCUIT ANALYSISASIAN JOURNAL OF CONTROL, Issue 2 2007Wenle Zhang ABSTRACT Due to existence of concurrent part flows and resource sharing in modern automated flexible manufacturing systems (FMS), deadlock is a common problem and its occurrence causes loss of productivity. When a manufacturing system is modeled by a digraph, existence of circuits in such a graph is a necessary condition for deadlock. Our previous work further showed that the knot and order of a circuit is closely related to impending deadlocks , a type of deadlock that is more difficult to detect. In this paper, we extend our previous work on deadlock avoidance for flexible manufacturing systems to allow choices in process flows (a.k.a., flexible part routing). Due to introduction of choices, part flow dynamics become more sophisticated and our previous results are no longer valid. A systematic circuit analysis is performed in this paper. New concepts such as broken circuit, basic circuit, choice circuit and supremal circuit are introduced to reduce significantly the number of circuits thus improving efficiency of our approach. The extended method is highly permissive with the adjusted effective free space calculation to capture more necessary parts flow dynamics, especially when multiple knots exist in the digraph model. The online policy runs in polynomial time once the set of basic circuits of the digraph is computed offline. Simulation results on selected examples are given. [source] Structure of a class II TrmH tRNA-modifying enzyme from Aquifex aeolicusACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2005Elizabeth Pleshe Biological RNAs contain a variety of post-transcriptional modifications that facilitate their efficient function in the cellular environment. One of the two most common forms of modification is methylation of the 2,-hydroxyl group of the ribose sugar, which is performed by a number of S -adenosylmethionine (SAM) dependent methyltransferases. In bacteria, many of these modifications in tRNA and rRNA are carried out by the ,/,-knot superfamily of enzymes, whose SAM-binding pocket is created by a characteristic deep trefoil knot. TrmH, an enzyme found throughout all three kingdoms of life, modifies the universally conserved guanosine 18 position of tRNA. The crystal structure of TrmH from the thermophilic bacterium Aquifex aeolicus has been determined at 1.85,Å resolution using data collected from a synchrotron-radiation source. The protein reveals a fold typical of members of the SpoU clan of proteins, a subfamily of the ,/,-knot superfamily, with ,-helical extensions at the N- and C-termini that are likely to be involved in tRNA binding. [source] Transfemoral percutaneous removal of a knotted Swan-Ganz catheter,CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 5 2009Athanasios Katsikis MD Abstract Intracardiac knotting of balloon-tipped flow-directed catheters during a heart catheterization procedure represents a rare but serious complication. In case that such an event occurs, leading to inability to remove the catheter, various different methods have been described to solve the problem, varying from the least invasive to open heart surgery. The formation of large knots requires surgical removal in the vast majority of cases. We describe the successful nonsurgical removal of a Swan-Ganz catheter, after the formation of a large double knot, during a right heart catheterization performed without fluoroscopic guidance in the intensive care unit. This technique could serve as a last resort in cases that surgical removal seems inevitable due to size-related inapplicability of other nonsurgical methods. © 2009 Wiley-Liss, Inc. [source] Old habits tie hard: an in vitro comparison of first-throw tension holding in Polyglycolic acid (Dexon S) and Polyglactin 910 (Coated Vicryl)CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 2 2006Thomas L Kersey MB BS Abstract Purpose:, To compare the first-throw tension holding property of two braided absorbable sutures commonly used in oculoplastic surgery. Methods:, The study was an in vitro experimental model. 6/0 Polyglycolic acid (Dexon S) and 6/0 Polyglactin 910 (Coated Vicryl) were compared using an experimental model to determine first-throw knot security. A polypropylene suture (Surgipro 2) was included as a benchmark to judge the apparatus by, ensuring that our experiment could be designed independently of the test suture materials. Increasing metric loads were applied to the first double throw of a surgical knot. Each suture was tested to the point of knot slipping and the critical tension recorded. All the sutures were kept wet during use. Three variations of the experiment were undertaken: experiment 1 , two metal loops brought together by the test suture; experiment 2 , two strips of tissue brought together by the test suture; and experiment 3 , a knot tied over a metal bar coated in tissue. The tissue used was processed cross-linked porcine dermal collagen (Permacol). Each experiment was repeated three times for each suture type and the mean value taken. Results:, Experiment 1: Dexon S 12.2 g (11, 12, 13.5), Coated Vicryl 2.5 g (2.5, 2.5, 2.5) and Surgipro 2 2.3 g (2, 2, 3); experiment 2: Dexon S 33.33 g (30, 35, 35), Coated Vicryl 25 g (25, 25, 25) and Surgipro 2 5 g (5, 5, 5); experiment 3: Dexon S 100 g (100, 100, 100), Coated Vicryl 56.667 g (60, 55, 55) and Surgipro 2 5 g (5, 5, 5). Conclusions:, Dexon S-braided absorbable suture has significantly better first-throw knot security when compared with Coated Vicryl. This is an important property when suturing tissues under tension as it minimizes slippage before the locking throw is tied. [source] Novel Face-Lift Suspension Suture and Inserting Instrument: Use of Large Anchors Knotted into a Suture with Attached Needle and Inserting Device Allowing for Single Entry Point Placement of Suspension Suture.DERMATOLOGIC SURGERY, Issue 3 2006Preliminary Report of 20 Cases with 6- to 12-Month Follow-Up BACKGROUND Various suspension suture techniques exist to elevate the mid-face, jowls, and neck. OBJECTIVE To assess safety and efficacy of a new suspension suture and inserting instrument with both standard and minimal incision (no-skin-excision) face-lifts. METHODS A new type of multianchor suspension suture assembled from commercially available 2-0 absorbable monofilament material, with 5 to 9 equally spaced knots through which are secured 7 to 9 mm bits of 0 thickness similar suture material, and an attached straightened needle, was used to elevate and suspend facial tissues to temporal or mastoid fascia. The suspension sutures are placed in the deep subcutaneous tissues, just above the superficial musculo aponeurotic system (SMAS), by use of a novel, blunt instrument, which does not require a second, distal exit point. The suspension suture distal end floats free. The proximal needle end is sutured to fascia. The suture was used on 20 patients. Fourteen of them underwent pure, "no-skin-excision," suspension lifts. Six had suspension suture elevation of the mid-face in conjunction with relatively conservative open lifts. Nine- to 12-month results were evaluated. RESULTS With open face-lifts, 9- to 12-month results are excellent with significant persistence of the correction initially achieved. Resulting scars remained fine line. There were no complications. With pure suspension lifts, initial results were impressive. By 6 months, correction started to fade. By 12 months 100% of initial correction for jowls, and 80 to 100% for mid-face, appeared lost. Recovery time was 2 to 4 days. There were no significant complications. CONCLUSION Large multianchor, absorbable monofilament sutures can safely and effectively enhance results of conservative lifts, with remarkable elevation of the mid-face not achievable with simple SMAS flaps. These suspension sutures can easily and safely achieve impressive, though relatively short-term results, with a minimal incision, "no-skin-excision" technique. [source] 1, 2, 3, 4: Four Techniques to Secure Buried KnotsDERMATOLOGIC SURGERY, Issue 7 2002Daniel A. Davis MD background. High tension wounds can be difficult to close. objective. To enumerate methods for securing a surgeon's knot when tying buried sutures under tension. conclusion. The tension tranfer stitch is a swift and elegant method to secure surgeon's knots. [source] The Thread & Cut Method: Syntheses of Molecular Knot Precursors,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2008Edward E. Fenlon Abstract A novel approach to molecular knots is described. This method may allow access to smaller and more complex knots. Two knot precursors, 1a and 1b, are efficiently prepared in overall yields of 9.6,% and 8.7,%, respectively. The convergent six-step syntheses utilize Fréchet-type etherifications, alkyne/azide click cycloadditions, and bis-macrolactonizations.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] | ||||||||||||||||||||||||||||