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Tight
Terms modified by Tight Selected AbstractsOBTAINING FRACTURE INFORMATION FOR LOW-PERMEABILITY (TIGHT) GAS SANDSTONES FROM SIDEWALL CORESJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2006S. E. Laubach We illustrate a fracture characterization technique applicable to all tight gas sandstones. The technique uses microfractures and cements in the rock mass identified using SEM-based cathodoluminescence imaging to provide information on unsampled large fractures, including strike and cross-cutting relationships, intensity, and likelihood of preserved open fractures. We applied the technique in two tight gas sandstone wells in the Pennsylvanian Pottsville Formation, Black Warrior Basin, Alabama, USA. In one well, data was obtained entirely from drilled 1,inch diameter sidewall cores that were oriented using image logs and features visible in cores. We predicted fracture porosity preservation in large fractures using late cements in the rock mass as a proxy for fracture observation. Results from the technique are consistent with what is known of large fractures in this area. Where we predicted open, high intensity fractures, substantial gas flares were observed during drilling. By combining microstructural and diagenetic observations, it is possible to overcome the inadequate fracture sampling that plagues evaluation of natural fractures and that relies solely on observations of macroscopically visible fractures. [source] Chromophore Interaction in Xanthorhodopsin,Retinal Dependence of Salinixanthin Binding,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Eleonora S. Imasheva Xanthorhodopsin is a light-driven proton pump in the extremely halophilic bacterium Salinibacter ruber. Its unique feature is that besides retinal it has a carotenoid, salinixanthin, with a light harvesting function. Tight and specific binding of the carotenoid antenna is controlled by binding of the retinal. Addition of all- trans retinal to xanthorhodopsin bleached with hydroxylamine restores not only the retinal chromophore absorption band, but causes sharpening of the salinixanthin bands reflecting its rigid binding by the protein. In this report we examine the correlation of the changes in the two chromophores during bleaching and reconstitution with native all- trans retinal, artificial retinal analogs and retinol. Bleaching and reconstitution both appear to be multistage processes. The carotenoid absorption changes during bleaching occurred not only upon hydrolysis of the Schiff base but continued while the retinal was leaving its binding site. In the case of reconstitution, the 13-desmethyl analog formed the protonated Schiff base slower than retinal, and provided the opportunity to observe changes in carotenoid binding at various stages. The characteristic sharpening of the carotenoid bands, indicative of its reduced conformational heterogeneity in the binding site, occurs when the retinal occupies the binding site but the covalent bond to Lys-240 via a Schiff base is not yet formed. This is confirmed by the results for retinol reconstitution, where the Schiff base does not form but the carotenoid exhibits its characteristic spectral change from the binding. [source] A bis(amine,carboxylate) copper(II) coordination compound forms a two-dimensional metal,organic framework when crystallized from water and methanolACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009Orde Q. Munro When {2,2,-[(2-methyl-2-nitropropane-1,3-diyl)diimino]diacetato}copper(II), [Cu(C8H13N3O6)], (I), was crystallized from a binary mixture of methanol and water, a monoclinic two-dimensional water- and methanol-solvated metal,organic framework (MOF) structure, distinctly different from the known orthorhombic one-dimensional coordination polymer of (I), was isolated, namely catena -poly[[copper(II)-,3 -2,2,-[(2-methyl-2-nitropropane-1,3-diyl)diimino]diacetato] methanol 0.45-solvate 0.55-hydrate], {[Cu(C8H13N3O6)]·0.45CH3OH·0.55H2O}n, (II). The monoclinic structure of (II) comprises centrosymmetric dimers stabilized by a dative covalent Cu2O2 core and intramolecular N,H...O hydrogen bonds. Each dimer is linked to four neighbouring dimers via symmetry-related (opposing) pairs of bridging carboxylate O atoms to generate a `diamondoid' net or two-dimensional coordination network. Tight voids of 166,Å3 are located between these two-dimensional MOF sheets and contain a mixture of water and methanol with fractional occupancies of 0.55 and 0.45, respectively. The two-dimensional MOF sheets have nanometre-scale spacings (11.2,Å) in the crystal structure. Hydrogen-bonding between the methanol/water hydroxy groups and a Cu-bound bridging carboxylate O atom apparently negates thermal desolvation of the structure below 358,K in an uncrushed crystal of (II). [source] Psychometric characteristics of dyspnea descriptor ratings in emergency department patients with exacerbated chronic obstructive pulmonary disease,RESEARCH IN NURSING & HEALTH, Issue 5 2002Mark B. Parshall Abstract The purpose of this study was to evaluate the reliability, content validity, and factor structure of dyspnea sensory quality descriptor ratings in emergency department (ED) patients with exacerbated chronic obstructive pulmonary disease (COPD). During an ED visit 104 patients with COPD rated the intensity of 16 dyspnea sensory quality descriptors (numerical ratings of 0,10) in relation to how they felt when they decided to come to the ED (Decision) and 1 week before the visit. Content validity of 15 descriptors was supported. Factor analysis of Decision ratings resulted in seven descriptors and three factors (,=.88; 74% common variance): Smothering/Suffocating/Hunger for air (,=.87); Effort/Work (,=.87); and Tight/Constricted (,=.74). Results indicate that the intensity of sensory quality descriptors can be measured reliably in COPD patients during an exacerbation of COPD. The initial descriptor list of descriptors could be cut by more than half while retaining satisfactory psychometric properties. © 2002 Wiley Periodicals, Inc. Res Nurs Health 25:331,344, 2002 [source] Interactive shadowing for 2D AnimeCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 2-3 2009Eiji Sugisaki Abstract In this paper, we propose an instant shadow generation technique for 2D animation, especially Japanese Anime. In traditional 2D Anime production, the entire animation including shadows is drawn by hand so that it takes long time to complete. Shadows play an important role in the creation of symbolic visual effects. However shadows are not always drawn due to time constraints and lack of animators especially when the production schedule is tight. To solve this problem, we develop an easy shadowing approach that enables animators to easily create a layer of shadow and its animation based on the character's shapes. Our approach is both instant and intuitive. The only inputs required are character or object shapes in input animation sequence with alpha value generally used in the Anime production pipeline. First, shadows are automatically rendered on a virtual plane by using a Shadow Map1 based on these inputs. Then the rendered shadows can be edited by simple operations and simplified by the Gaussian Filter. Several special effects such as blurring can be applied to the rendered shadow at the same time. Compared to existing approaches, ours is more efficient and effective to handle automatic shadowing in real-time. Copyright © 2009 John Wiley & Sons, Ltd. [source] AKAP-independent localization of type-II protein kinase A to dynamic actin microspikesCYTOSKELETON, Issue 9 2009Robert L. Rivard Abstract Regulation of the cyclic AMP-dependent protein kinase (PKA) in subcellular space is required for cytoskeletal dynamics and chemotaxis. Currently, spatial regulation of PKA is thought to require the association of PKA regulatory (R) subunits with A-kinase anchoring proteins (AKAPs). Here, we show that the regulatory RII, subunit of PKA associates with dynamic actin microspikes in an AKAP-independent manner. Both endogenous RII, and a GFP-RII, fusion protein co-localize with F-actin in microspikes within hippocampal neuron growth cones and the leading edge lamellae of NG108-15 cells. Live-cell imaging demonstrates that RII,-associated microspikes are highly dynamic and that the coupling of RII, to actin is tight, as the movement of both actin and RII, are immediately and coincidently stopped by low-dose cytochalasin D. Importantly, co-localization of RII, and actin in these structures is resistant to displacement by a cell-permeable disrupter of PKA-AKAP interactions. Biochemical fractionation confirms that a substantial pool of PKA RII, is associated with the detergent-insoluble cytoskeleton and is resistant to extraction by a peptide inhibitor of AKAP interactions. Finally, mutation of the AKAP-binding domain of RII, fails to disrupt its association with actin microspikes. These data provide the first demonstration of the physical association of a kinase with such dynamic actin structures, as well as the first demonstration of the ability of type-II PKA to localize to discrete subcellular structures independently of canonical AKAP function. This association is likely to be important for microfilament dynamics and cell migration and may prime the investigation of novel mechanisms for localizing PKA activity. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source] To generalize or not to generalize: spatial categories are influenced by physical attributes and languageDEVELOPMENTAL SCIENCE, Issue 1 2009Susan J. Hespos The current work explored the conditions under which infants generalize spatial relationships from one event to another. English-learning 5-month-olds habituated to a tight- or loose-fit covering event dishabituated to a change in fit during a containment test event, but infants habituated to a visually similar occlusion event did not. Thus, infants' responses appeared to be driven by the physical nature of the fit rather than visual similarity. This response pattern was replicated with Korean-speaking adults, but English-speaking adults showed no sensitivity to change in fit for either event. These findings suggest that language development links linguistic forms to universal, pre-existing representations of meaning, and that linguistic experience can shape sensitivity to distinctions that are marked in one's native language. [source] How tight is the UK labour market?ECONOMIC OUTLOOK, Issue 4 2004Article first published online: 14 OCT 200 With the unemployment rate touching 25-year lows and some signs of a pick-up in earnings growth, concern has again focussed on how much scope the labour market has to meet the requirements of the above-trend growth forecast for the UK. This article by David Tinsley reviews some of the evidence for how ,tight' the UK labour market is. It suggests that, although the labour market has probably tightened over the last year or so, the headline figures give a somewhat misleading picture. It goes on to argue that there are a number of other margins for adjustment by which the demands of the robust growth forecast for the UK over the next few years can be met without igniting significant inflationary pressure. [source] TERRORISM AND THE RETURNS TO OILECONOMICS & POLITICS, Issue 3 2009BROCK BLOMBERG The effect of terrorism on global oil prices has been largely explained through demand-side effects. We estimate an empirical model to re-examine the effect of terrorism on the price of global oil stocks across oil market regimes that reflect different supply constraints. We believe that terrorism will have larger impacts when global capacity is tight (i.e. when global demand is close to global supply). This means that any shock to capacity (say by conflict) should have the largest impact on profits before the first OPEC shock in the early 1970s. Since then, conflict shocks would not allow firms to exploit production in the same way, thus reducing the available profits that could be garnered by such production manipulation. If capacity constraints are binding when a conflict occurs, then we predict that a positive stock price reaction can be expected for oil firms from such a shock. We exploit a new panel dataset to investigate the relationship between oil profitability and conflict, using conflict data from the top 20 oil producing and exporting countries in the world. We show that in the later part of our sample, 1974,2005, as cartel behavior of OPEC member countries has diminished and as conflict has become more regular and thus the information surrounding it noisier, oil stock prices do not increase in response to conflict. However, in earlier capacity constrained eras, we find that oil stocks can in fact increase in response to conflict. In some cases, the impact of conflict may cause the return of oil stocks to increase by as much as 10 percentage points. [source] Cash Flow Sensitivity of InvestmentEUROPEAN FINANCIAL MANAGEMENT, Issue 1 2009Armen Hovakimian G30; G31; G32 Abstract Investment cash flow sensitivity is associated with both underinvestment when cash flows are low and overinvestment when cash flows are high. The accessibility of external capital is positively correlated with cash flows, intensifying investment cash flow sensitivity. Managers actively counteract the variations in internal and external liquidity by accumulating working capital when liquidity is high and draining it when liquidity is low. These results imply that cash flow sensitive firms face financial constraints, which are binding in low cash flow years. Traditional indicators of financial constraints, such as size and dividend payout, successfully distinguish firms that may potentially face constraints, but are less successful in distinguishing between periods of tight and relaxed constraints. These periods are much more clearly separated by the KZ index, which, on the other hand, is less successful in identifying firms that are likely to face liquidity constraints. [source] The evaluative face of a descriptive model: Communion and agency in Peabody's tetradic model of trait organizationEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 7 2008Guido Peeters An important strand of research on cognitive trait organization is connected with Peabody's (1967) tetradic model stressing two non-evaluative dimensions: tight,loose and assertive,unassertive. The relationship of this model with the communion/agency model involving two evaluative dimensions is discussed and empirically investigated. It is shown that the models are orthogonally related suggesting four trait categories: agentic tight,loose, communal tight,loose, agentic assertive,unassertive and communal assertive,unassertive. Implications are discussed regarding the interpretation of stereotype contents, the validity of the tetradic and communion/agency models and the development of a functionalist approach of social perception and judgment. Copyright © 2008 John Wiley & Sons, Ltd. [source] Maximum Residue Limits of Veterinary Medicinal Products and Their Regulation in European Community LawEUROPEAN LAW JOURNAL, Issue 2 2003Robert Ancuceanu This paper proposes a legal analysis of a legal and empirical tool (maximum residue limits (MRLs)) designed to protect the consumers of animal foodstuffs, as it is regulated in European Community law. After introducing the concept of MRLs in its legal context, MRLs are defined and the need for harmonisation in this field is explained. Then the main rules governing the establishment of MRLs at a Europe-wide level are expounded, an important place being devoted to some problems occurred in the cases decided by the European Court of Justice: is it possible to establish an MRL only for certain therapeutic indications? What about the intention of placing on the market in the establishment of an MRL? Is the procedure for the establishment of MRLs a tight or lax one? The answer to some of these questions involves more general aspects of European Community law. [source] EVOLUTION OF MIGRATION UNDER KIN SELECTION AND LOCAL ADAPTATIONEVOLUTION, Issue 1 2005Sylvain Billiard Abstract We present here a stochastic two-locus, two-habitat model for the evolution of migration with local adaptation and kin selection. One locus determines the migration rate while the other causes local adaptation. We show that the opposing forces of kin competition and local adaptation can lead to the existence of one or two convergence stable migration rates, notably depending on the recombination rate between the two loci. We show that linkage between migration and local adaptation loci has two antagonist effects: when linkage is tight, cost of local adaptation increases, leading to smaller equilibrium migration rates. However, when linkage is tighter, the population structure at the migration locus tends to be very high because of the indirect selection, and thus equilibrium migration rates increases. This result, qualitatively different from results obtained with other models of migration evolution, indicates that ignoring drift or the detail of the genetic architecture may lead to incorrect conclusions. [source] Crystal structure of the parasite inhibitor chagasin in complex with papain allows identification of structural requirements for broad reactivity and specificity determinants for target proteasesFEBS JOURNAL, Issue 3 2009Izabela Redzynia A complex of chagasin, a protein inhibitor from Trypanosoma cruzi, and papain, a classic family C1 cysteine protease, has been crystallized. Kinetic studies revealed that inactivation of papain by chagasin is very fast (kon = 1.5 × 106 m,1·s,1), and results in the formation of a very tight, reversible complex (Ki = 36 pm), with similar or better rate and equilibrium constants than those for cathepsins L and B. The high-resolution crystal structure shows an inhibitory wedge comprising three loops, which forms a number of contacts responsible for the high-affinity binding. Comparison with the structure of papain in complex with human cystatin B reveals that, despite entirely different folding, the two inhibitors utilize very similar atomic interactions, leading to essentially identical affinities for the enzyme. Comparisons of the chagasin,papain complex with high-resolution structures of chagasin in complexes with cathepsin L, cathepsin B and falcipain allowed the creation of a consensus map of the structural features that are important for efficient inhibition of papain-like enzymes. The comparisons also revealed a number of unique interactions that can be used to design enzyme-specific inhibitors. As papain exhibits high structural similarity to the catalytic domain of the T. cruzi enzyme cruzipain, the present chagasin,papain complex provides a reliable model of chagasin,cruzipain interactions. Such information, coupled with our identification of specificity-conferring interactions, should be important for the development of drugs for treatment of the devastating Chagas disease caused by this parasite. [source] DNA supercoiling in Escherichia coli is under tight and subtle homeostatic control, involving gene-expression and metabolic regulation of both topoisomerase I and DNA gyraseFEBS JOURNAL, Issue 6 2002Jacky L. Snoep DNA of prokaryotes is in a nonequilibrium structural state, characterized as ,active' DNA supercoiling. Alterations in this state affect many life processes and a homeostatic control of DNA supercoiling has been suggested [Menzel, R. & Gellert, M. (1983) Cell34, 105,113]. We here report on a new method for quantifying homeostatic control of the high-energy state of in vivo DNA. The method involves making small perturbation in the expression of topoisomerase I, and measuring the effect on DNA supercoiling of a reporter plasmid and on the expression of DNA gyrase. In a separate set of experiments the expression of DNA gyrase was manipulated and the control on DNA supercoiling and topoisomerase I expression was measured [part of these latter experiments has been published in Jensen, P.R., van der Weijden, C.C., Jensen, L.B., Westerhoff, H.V. & Snoep, J.L. (1999) Eur. J. Biochem.266, 865,877]. Of the two regulatory mechanisms via which homeostasis is,conferred, regulation of enzyme activity or regulation of enzyme expression, we quantified the first to be responsible for 72% and the latter for 28%. The gene expression regulation could be dissected to DNA gyrase (21%) and to topoisomerase I (7%). On a scale from 0 (no homeostatic control) to 1 (full homeostatic control) we quantified the homeostatic control of DNA supercoiling at 0.87. A 10% manipulation of either topoisomerase I or DNA gyrase activity results in a 1.3% change of DNA supercoiling only. We conclude that the homeostatic regulation of the nonequilibrium DNA structure in wild-type Escherichia coli is almost complete and subtle (i.e. involving at least three regulatory mechanisms). [source] The loose coupling mechanism in molecular machines of living cellsGENES TO CELLS, Issue 1 2000Fumio Oosawa Living cells have molecular machines for free energy conversion, for example, sliding machines in muscle and other cells, flagellar motors in bacteria, and various ion pumps in cell membranes. They are constructed from protein molecules and work in the nm (nanometer), pN (piconewton) and ms (millisecond) ranges, without inertia. In 1980s, a question was raised of whether the input,output or influx,efflux coupling in these molecular machines is tight or loose, and an idea of loose coupling was proposed. Recently, the long-distance multistep sliding of a single myosin head on an actin filament, coupled with the hydrolysis of one ATP molecule, was observed by Yanagida's group using highly developed techniques of optical microscopy and micromanipulation. This gave direct evidence for the loose coupling between the chemical reaction and the mechanical event in the sliding machine. In this review, I will briefly describe a historical overview of the input,output problem in the molecular machines of living cells. [source] Variable structure robust state and parameter estimatorINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 2 2001Alex S. Poznyak Abstract The problem of simultaneous robust state and parameters estimation for a class of SISO non-linear systems under mixed uncertainties (unmodelled dynamics as well as observation noises) is addressed. A non-linear variable structure robust ,observer,identifier' is introduced to obtain the corresponding estimates. Lie derivative technique is used to obtain the observability conditions for the equivalent extended non-linear system. It is shown that, in general, the extended system can lose the global observability property and a special procedure is needed to work well in this situation. The suggested adaptive observer has the non-linear high-gain observer structure with adjusted parameters that provides ,a good' upper bound for the identification error performance index. The van der Monde transformation is used to derive this bound which turns out to be tight. Three examples dealing with a simple pendulum, the Duffing equation and the van del Pol oscillator are considered to illustrate the effectiveness of the suggested approach. Copyright © 2001 John Wiley & Sons, Ltd. [source] On the error probability of quasi-orthogonal space,time block codesINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2008Jae-Dong Yang Abstract In this paper, we derive the exact pairwise error probabilities (PEPs) of various quasi-orthogonal space,time block codes (QO-STBCs) using the moment generating function. By classifying the exact PEPs of QO-STBCs into three types, we derive the closed-form expression for each type of PEP. Based on these closed-form expressions, we obtain the union bounds on the symbol error probability and bit error probability for QPSK modulation. Through simulation, it is shown that these union bounds are quite tight. Copyright © 2008 John Wiley & Sons, Ltd. [source] Climatic effects on timing of spring migration and breeding in a long-distance migrant, the pied flycatcher Ficedula hypoleucaJOURNAL OF AVIAN BIOLOGY, Issue 5 2005Christiaan Both Climate change has advanced the breeding dates of many bird species, but for few species we know whether this advancement is sufficient to track the advancement of the underlying levels of the food chain. For the long-distance migratory pied flycatcher Ficedula hypoleuca the advancement in breeding time has been insufficient to maintain the synchrony with their main food sources. The timing of arrival in the breeding areas from their African wintering grounds is likely to constrain the advancement of breeding date. We hypothesise that this is because in Africa they cannot predict the advancement of spring in their breeding habitat. However, long-distance migrants may advance their arrival time by migrating faster when circumstances en route are favourable. In this study we show that both arrival and breeding date depend on temperatures at their main North African staging grounds, as well as on temperature at the breeding grounds. Male arrival and average laying date were not correlated, but the positive effect of temperature in North Africa on breeding dates suggests that breeding date is indeed constrained by arrival of females. Long-distance migrants thus are able to adjust arrival and hence breeding by faster spring migration, but the degree of adjustment is probably limited as timing schedules in spring are tight. Furthermore, as climate change is affecting temperatures differently along the migratory flyway and the breeding areas, it is unlikely that arrival dates are advanced at the same rate as the timing of breeding should advance, given the advancement of the underlying levels of the food chain. [source] The distribution,abundance (density) relationship: its form and causes in a tropical mammal order, PrimatesJOURNAL OF BIOGEOGRAPHY, Issue 4 2005A. H. Harcourt Abstract Aim, Across a wide variety of organisms, taxa with high local densities (abundance) have large geographical ranges (distributions). We use primatology's detailed knowledge of its taxon to investigate the form and causes of the relationship in, unusually for macroecological analysis, a tropical taxon. Location, Africa, Central and South America, Asia, Madagascar. Methods, To investigate the form of the density,range relationship, we regressed local density on geographical range size, and also on female body mass, because in the Primates, density correlates strongly with mass. To investigate the biological causes of the relationship, we related (1) abundance (density × range size) and (2) residuals from the density,range regression lines to various measures of (i) resource use, (ii) reproductive rate and (iii) potential specialization. All data are from the literature. Analyses were done at the level of species (n = 140), genera (n = 60) and families/subfamilies (n = 17). We present various levels of results, including for all data, after omission of outlier data, after correction for phylogenetic dependence, and after Bonferroni correction of probabilities for multiple comparisons. Results, Regarding the form of the relationship, Madagascar primates are clear outliers (high densities in small ranges). Among the remaining three realms, the relation of density to range is weak or non-existent at the level of species and genera. However, it is strong, tight and linear at the level of families/subfamilies (r2 = 0.6, F1,10 = 19, P < 0.01). Although among primates, density is very significantly related to mass, at no taxonomic level is range size related to body mass. Consequently, removing the effects of mass makes little to no difference to density,range results. Regarding the biology of the relationship, only traits indicative of specialization are associated with abundance (meaning numbers): rare taxa are more specialized than are abundant taxa. The association is largely via range size, not density. Across families, no traits correlate significantly with the density,range relationship, nor with deviations from it, despite the strength of the relationship at this taxonomic level. Main conclusions, We suggest that in macroecology, analysis at taxonomic levels deeper than that of the relatively ephemeral species can be appropriate. We argue that the several purely methodological explanations for the positive density,range size relationship in primates can be rejected. Of the various biological hypotheses, those having to do with specialization,generalization seem the only applicable ones. The fact that the relationship is entirely via range size, not via density, means that while we might have a biology of range size, we do not yet have one of the density,geographical range relationship. It is probably time to search for multivariate explanations, rather than univariate ones. However, we can for the first time, for at least primates, suggest that any association of abundance or range size with specialization is via the number of different subtaxa, not the average degree of specialization of each subtaxon. The implication for conservation is obvious. [source] Signal generation and Raman-resonant imaging by non-degenerate four-wave mixing under tight focusing conditionsJOURNAL OF BIOPHOTONICS, Issue 3 2010Tyler Weeks Abstract The authors demonstrate Raman-resonant imaging based on the simultaneous generation of several nonlinear frequency mixing processes resulting from a 3-color coherent anti-Stokes Raman scattering (CARS) experiment. The interaction of three coincident short-pulsed laser beams simultaneously generates both 2-color (degenerate) CARS and 3-color (non-degenerate) CARS signals, which are collected and characterized spectroscopically , allowing for resonant, doubly-resonant, and non-resonant contrast mechanisms. Images obtained from both 2-color and 3-color CARS signals are compared and found to provide complementary information. The 3-color CARS microscopy scheme provides a versatile multiplexed modality for biological imaging, which may extend the capabilities of label-free non-linear microscopy, e.g. by probing multiple Raman resonances. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] d -Regular graphs of acyclic chromatic index at least d+2JOURNAL OF GRAPH THEORY, Issue 3 2010Manu Basavaraju Abstract An acyclic edge coloring of a graph is a proper edge coloring such that there are no bichromatic cycles. The acyclic chromatic index of a graph is the minimum number k such that there is an acyclic edge coloring using k colors and is denoted by a,(G). It was conjectured by Alon, Sudakov and Zaks (and earlier by Fiamcik) that a,(G),,+2, where ,=,(G) denotes the maximum degree of the graph. Alon et al. also raised the question whether the complete graphs of even order are the only regular graphs which require ,+2 colors to be acyclically edge colored. In this article, using a simple counting argument we observe not only that this is not true, but in fact all d -regular graphs with 2n vertices and d>n, requires at least d+ 2 colors. We also show that a,(Kn, n),n+ 2, when n is odd using a more non-trivial argument. (Here Kn, n denotes the complete bipartite graph with n vertices on each side.) This lower bound for Kn, n can be shown to be tight for some families of complete bipartite graphs and for small values of n. We also infer that for every d, n such that d,5, n,2d+ 3 and dn even, there exist d -regular graphs which require at least d+2-colors to be acyclically edge colored. © 2009 Wiley Periodicals, Inc. J Graph Theory 63: 226,230, 2010 [source] The last excluded case of Dirac's map-color theorem for choosabilityJOURNAL OF GRAPH THEORY, Issue 4 2006Daniel Král' Abstract In 1890, Heawood established the upper bound on the chromatic number of every graph embedded on a surface of Euler genus , , 1. Almost 80 years later, the bound was shown to be tight by Ringel and Youngs. These two results have became known under the name of the Map-Color Theorem. In 1956, Dirac refined this by showing that the upper bound H(,) is obtained only if a graph G contains KH, as a subgraph except for three surfaces. Albertson and Hutchinson settled these excluded cases in 1979. This result is nowadays known as Dirac's Map-Color Theorem. Böhme, Mohar, and Stiebitz extended Dirac's Map-Color Theorem to the case of choosability by showing that G is (H(,) , 1)-choosable unless G contains KH(,) as a subgraph for , , 1 and , , 3. In the present paper, we settle the excluded case of , = 3. © 2005 Wiley Periodicals, Inc. J Graph Theory 51: 319,354, 2006 [source] Some remarks on dominationJOURNAL OF GRAPH THEORY, Issue 3 2004D. Archdeacon Abstract We prove a conjecture of Favaron et al. that every graph of order n and minimum degree at least three has a total dominating set of size at least n/2. We also present several related results about: (1) extentions to graphs of minimum degree two, (2) examining graphs where the bound is tight, and (3) a type of bipartite domination and its relation to transversals in hypergraphs. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 207,210, 2004 [source] Garnet porphyroblast timing and behaviour during fold evolution: implications from a 3-D geometric analysis of a hand-sample scale fold in a schistJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2003N. E. Timms Abstract Detailed 3-D analysis of inclusion trails in garnet porphyroblasts and matrix foliations preserved around a hand-sample scale, tight, upright fold has revealed a complex deformation history. The fold, dominated by interlayered quartz,mica schist and quartz-rich veins, preserves a crenulation cleavage that has a synthetic bulk shear sense to that of the macroscopic fold and transects the axis in mica-rich layers. Garnet porphyroblasts with asymmetric inclusion trails occur on both limbs of the fold and display two stages of growth shown by textural discontinuities. Garnet porphyroblast cores and rims pre-date the macroscopic fold and preserve successive foliation inflection/intersection axes (FIAs), which have the same trend but opposing plunges on each limb of the fold, and trend NNE,SSW and NE,SW, respectively. The FIAs are oblique to the main fold, which plunges gently to the WSW. Inclusion trail surfaces in the cores of idioblastic porphyroblasts within mica-rich layers define an apparent fold with an axis oblique to the macroscopic fold axis by 32°, whereas equivalent surfaces in tabular garnet adjacent to quartz-rich layers define a tighter apparent fold with an axis oblique to the main fold axis by 17°. This potentially could be explained by garnet porphyroblasts that grew over a pre-existing gentle fold and did not rotate during fold formation, but is more easily explained by rotation of the porphyroblasts during folding. Tabular porphyroblasts adjacent to quartz-rich layers rotated more relative to the fold axis than those within mica-rich layers due to less effective deformation partitioning around the porphyroblasts and through quartz-rich layers. This work highlights the importance of 3-D geometry and relative timing relationships in studies of inclusion trails in porphyroblasts and microstructures in the matrix. [source] SNi fragmentations of alkoxychlorocarbenes , a perspectiveJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 1 2007Robert A. Moss Abstract After a review of the early literature concerning SNi fragmentations of alkyl chlorosulfites and chloroformates, we present experimental and computational results for the SNi fragmentations of alkoxychlorocarbenes. Examples include cyclohexyloxychlorocarbene, 7-norbornyloxychlorocarbene, 3-nortricyclyloxychlorocarbene, exo -5-norbornenyl-2-oxychlorocarbene, and endo -5-norbornenyl-2-oxychlorocarbene. Computations generate a ,family' of closely related charge-separated SNi structures which approximate asynchronous, polar, concerted transition states and tight, short-lived ion pair intermediates. The precise description and behavior of these species in a given reaction depends on the identities of the alkyl group, the potential counterion, and the solvent. Copyright © 2007 John Wiley & Sons, Ltd. [source] The discovery of two kinds of ion pairsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2004Johannes Smid Abstract The discovery and implications of the existence of two kinds of ion pairs in solutions of carbanion salts is described. Also discussed are the factors controlling tight,loose ion pair equilibrium: the nature of the carbanion and its counterion, temperature, pressure, solvent, and cation-complexing additives. A few examples are presented of the effect of these ionic species on the mechanisms of anionic polymerization and proton transfer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3655,3667, 2004 [source] Corrosion of Dental Magnet Attachments for Removable Prostheses on Teeth and ImplantsJOURNAL OF PROSTHODONTICS, Issue 4 2009Arne F. Boeckler DMD, Dr Med Dent Abstract Purpose: For a long time, the use of magnets for the anchorage of dental prostheses failed due to lack of biocompatibility and the magnets' high susceptibility to corrosion in the mouth. These facts make encapsulation of the magnetic alloy with a corrosion-resistant, tight, and functionally firm sealing necessary. Due to different products and analysis methods, it is not feasible to compare the findings for contemporary products with the sparse and rather old test results in the literature. Therefore, the aim of this study was the standardized control and the comparison of the corrosion behavior of modern magnetic attachments for use on teeth and dental implants. Materials and Methods: Thirty-seven components of magnetic attachments on implants and natural teeth from different alloys (NdFeB, SmCo, Ti, CrMoMnTiFe, etc.) as delivered by the manufacturers or fabricated according to their instructions were examined for their corrosion behavior using the statical immersion analysis (ISO 10271:2001). Four specimens of every product with the same design were used. An uncased SmCo magnet served as control. Analyses after 1, 4, 7, and 28 days of the storage in corrosion solution were made. The eluate was examined quantitatively on the alloy components of the respective component with the help of optical emission spectrometry (,g/cm2). The results were compared to the requirements of ISO standard 22674:2006. In addition, existing corrosion products were also defined in the solution after 28 days. The results were analyzed descriptively and statistically to determine possible significant differences (t -test and Mann-Whitney-Wilcoxon rank-sums test; p < 0.05). Results: Dissolved metal ions could be found on all tested products. The release after 1 and 4 days was different for all specimens. In the group of implant abutments, the highest ion release after 7 days was found (all measurements ,g/cm2): Fe (13.94, Magfit-IP-IDN dome type), Pd (1.53, Medical-anchor), Cr (1.32, Magfit-IP-IDN dome type), Ti (1.09, Magfit-IP-IDN abutment), Co (0.81, Medical-anchor), and B (0.6, Magfit-IP-IDN dome type). After 28 days, the analyzed ion release increased irregularly: Fe (173.58, Magfit-IP-IDN dome type), Pd (44.17, Medical-anchor), Cr (2.02, Magfit-IP-IDN dome type), Ti (2.11, Magfit-IP-IDN abutment), Co (26.13, Medical-anchor), B (1.77, Magfit-IP-IDN dome type), and Nd (79.18, Magfit-IP-IDN dome type). In the group of magnetic systems on natural teeth, the highest ion release after 7 days was found for Fe (4.81, Magfit DX 800 keeper), Cr (1.18, Magfit DX 800 keeper), Pd (0.21, Direct System Keeper), Ni (0.18, WR-Magnet S3 small), Co (0.12, Direct System Keeper), and Ti (0.09, Magna Cap , Mini). After 28 days, the analyzed ion release increased non-uniformly: Fe (31.92, Magfit DX 800 Keeper), Cr (6.65, Magfit DX 800 Keeper), Pd (18.19, Direct System Keeper), Ni (0.61, WR-Magnet S3 small), Co (10.94, Direct System Keeper), Ti (0.83, Magna Cap , Mini), and Pd (2.78, EFM Alloy). In contrast, the uncased control magnet showed an exponential release after 7 days of Sm ions (55.06) and Co-ions (86.83), after 28 days of Sm ions (603.91) and Co ions (950.56). The release of corrosion products of all tested products stayed significantly under the limit of 200 ,g/cm2 (ISO 22674:2006). In contrast, the non-encapsulated control magnet exceeded that limit significantly. Conclusion: The analysis of the corrosion behavior of modern magnetic attachments for use on teeth and dental implants according to ISO 10271:2001 showed that metal ions had dissolved on all specimens. In the case of one product, the magnet corroded. For this product, an improvement of the capsulation would be desirable. None of the products reached the limit specified in ISO 22674:2006. All products seem to be suitable for dental application. Further studies in regard to the specific biocompatibility and possible cytotoxic effects on mucosa and tissue would be desirable. [source] Opposed bilateral transposition flap: a simple and effective way to close large defects, especially of the limbsJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 5 2008R Verdolini Abstract Background, Excision of large tumours, particularly of the limbs, can be challenging because of problems related to wound repair. This is especially true of the lower legs, where skin is often tight and difficult to mobilize. Closure by flap, which would represent the first choice for defects usually between 12,15 mm to 38,40 mm diameter, is at risk of developing complications, such as end-flap necrosis or dehiscence due to skin tension. For larger defects, usually more than 40 to 45 mm diameter, grafting still remains the only realistic option in the majority of cases, with all the various problems associated with this procedure, such as lengthy healing times and the risk of developing leg ulcers, above all in elderly patients with impaired blood circulation. Second intention healing implies extraordinarily long healing times with often unacceptable delays in normal ambulation and activity. Objective, To find an alternative to the usual repair techniques and to try to reduce the risk of complications. Conclusions, We developed a relatively simple but effective technique for the closure of large wounds resulting from the excision of tumours. Our technique consists of two longitudinal, parallel, transposition flaps obtained from two opposite sides of the wound, with major axes orientated in the cephalic-caudal direction. The two flaps are then rotated around two fulcra placed at two extremes of the wound by approximately 90°. This relatively simple technique has never caused any of the ordinarily associated problems in terms of necrosis or ulcer development. In addition, dehiscence of sutures never occurred, given the fact that suture tension is minimal. Quick healing has resulted in the majority of cases, avoiding all the problems associated with grafting or other traditional flap techniques. [source] Cover Picture: Laser & Photon.LASER & PHOTONICS REVIEWS, Issue 5 2008Rev. 2(5)/200 An artist's conception of laser tweezers Raman spectroscopy: A single laser beam is focused through a high power microscope objective to create a tight, diffraction-limited spot, which results in a single-beam optical trap powerful enough to capture and suspend cells up to 30 microns in diameter. Photons from the same laser beam scatter off molecular bonds in the sample and are used to construct a full Raman spectrum of the sample (see inset).(Cover picture: J. Chan, S. Fore, S. Wachsmann-Hogiu, and T. Huser, pp. 325-349, in this issue). [source] | ||||||||||||||||||||||||||||||||||||||||