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Decay
Kinds of Decay Terms modified by Decay Selected AbstractsINVESTIGATING MATERIAL DECAY OF HISTORIC BUILDINGS USING VISUAL ANALYTICS WITH MULTI-TEMPORAL INFRARED THERMOGRAPHIC DATAARCHAEOMETRY, Issue 3 2010MARIA DANESE This paper shows how visual analytics methodology can be used to facilitate interpretation of multi-temporal thermographic imagery for the purpose of restoration of cultural heritage. We explore thermographic data in a visual environment from the unifying spatio-temporal perspective in an attempt to identify spatial and spatio-temporal patterns that could provide information about the structure and the level of decay of the material, and the presence of other physical phenomena in the wall. The approach is tested on a thermographic dataset captured on the façade of a Romanesque building from the 13th century,the Cathedral in Matera (Italy). [source] GEOCHEMICAL AND ENGINEERING GEOLOGICAL PROPERTIES OF THE VOLCANIC TUFFS USED IN THE ETRUSCAN TOMBS OF NORCHIA (NORTHERN LATIUM, ITALY) AND A STUDY OF THE FACTORS RESPONSIBLE FOR THEIR RAPID SURFACE AND STRUCTURAL DECAYARCHAEOMETRY, Issue 2 2010P. CICCIOLI The geochemical and engineering geological properties of the tuffs used in the rock-cut cliff tombs of the Etruscan necropolis of Norchia were investigated to evaluate their susceptibility to different weathering agents and confirm their origin. For the first time, materials were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT,IR), thermogravimetric analyses (TGA, DGA and DTG), scanning electron microscopy (SEM,EDS) and energy-dispersive X-ray fluorescence (ED,XRF), and their different origins confirmed. Tests of material properties indicate that both tuffs are poorly durable, but one of them is less susceptible to weathering. Although tombs made with the more resistant material show limited surface weathering, they undergo severe structural damage because of stress release and plant root infiltration. This, combined with the microclimatic conditions established inside river canyons, can trigger rock falls, leading ultimately to the complete destruction of these tombs. [source] Experimental Study and Modelling of Formation and Decay of Active Species in an Oxygen DischargeCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1 2005A.-M. Diamy Abstract A microwave (2.45 GHz) oxygen discharge (3 hPa, 150 W, 50 mL.min,1) is studied by optical emission spectroscopy of O(5P) (line 777.4 nm) and of the atmospheric system of O2(head-line 759.4 nm). Calibration of the spectral response of the optical setup is used to determine the concentrations of O(5P) and O2(b). The concentration of the O(5P) atoms is in the range 108,109 cm,3 and the concentration of the O2(b) molecules is in the range 1014 , 2 × 1014 cm,3 along the discharge tube. An attempt is made to simulate the experimental results by using coupling the Boltzmann equation, homogeneous energy transfer V-V and V-T, heterogeneous reactions on the walls (energy transfer and recombination of atoms) and a kinetic scheme (electronic transfer and chemical reactions). The Boltzmann equation includes momentum transfer, inelastic and superelastic processes and e-e collisions. V-V and V-T transfer equations are obtained from the SSH theory and the kinetic scheme includes 65 reactions with 17 species [electrons e, ions O, and O2,, fundamental electronic neutral species O(3P), O2, O2(X,v), O3 and excited neutral species O2(a), O2(b), O2(A), O(1D), O(1S), O(5P), O(4d 5Do), O(5s 5So), O(3d 5Do) and O(4s 5So)]. A fair agreement between experimental results and modelling is obtained with the following set of fitting values: , heterogeneous deactivation coefficient for O2(b) , = 2.6 × 10,2; , rate constant of reaction [O(1D) + O(3P) , 2 O(3P)] k34 = 1.4 × 10,11 cm3.s,1; , electron concentration in the range 1010 , 1011 cm,3. Modelling shows that the recombination coefficient for oxygen atoms on the silica wall (range 1.4 × 10,3 , 0.2 × 10,3) is of the same order as the values obtained in a previous paper and that the ratio ([O] / 2 [O2]initial) is about 33,50%. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Objects of Love and Decay: Colonial Photographs in a Postcolonial ArchiveCULTURAL ANTHROPOLOGY, Issue 2 2005Liam Buckley The poor condition of a collection of colonial photographs currently housed in the National Archives of The Gambia is the subject of a variety of competing discourses and practices concerning the preservation of colonial visual culture. At issue is the question of who has the right to look after the artifacts of material culture as they inevitably expire. I suggest that the discourse surrounding decaying colonial photographs is a lover's discourse. The decay causes controversy because it reminds us of our feelings for, and intimacy with, colonial culture and asks that we imagine ways of finally letting go. [source] Generation, Spectroscopic Characterization by EPR, and Decay of a Pyranine-Derived RadicalHELVETICA CHIMICA ACTA, Issue 10 2007Carolina Aliaga Abstract The pyraninoxyl radical is readily formed from the MnO2 -promoted oxidation of pyranine. The free radical can be formed in high concentrations (mM), and presents a characteristic EPR spectrum that indicates a high spin-density delocalization. It is relatively stable under nitrogen (half-life ca. 50,min) but readily decays in presence of O2. In spite of its high stability, the radical readily reacts with antioxidants (phenols and ascorbic acid) with a partial recovery of the parent pyranine. High concentrations of the pyraninoxyl radical (ca. 9,,M) are present when pyranine is exposed to a free radical source (10,mM 2,2,-azobis[2-amidinopropane], 37°). The fact that these radicals readily react with antioxidants (ascorbic acid and caffeic acid) supports the proposal that protection by antioxidants of peroxyl radical-promoted pyranine bleaching is mainly due to the occurrence of a repair mechanism. [source] Nutrient Uptake and Mineralization during Leaf Decay in Streams , a Model SimulationINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 4 2009J. R. Webster Abstract We developed a stoichiometrically explicit computer model to examine how heterotrophic uptake of nutrients and microbial mineralization occurring during the decay of leaves in streams may be important in modifying nutrient concentrations. The simulations showed that microbial uptake can substantially decrease stream nutrient concentrations during the initial phases of decomposition, while mineralization may produce increases in concentrations during later stages of decomposition. The simulations also showed that initial nutrient content of the leaves can affect the stream nutrient concentration dynamics and determine whether nitrogen or phosphorus is the limiting nutrient. Finally, the simulations suggest a net retention (uptake > mineralization) of nutrients in headwater streams, which is balanced by export of particulate organic nutrients to downstream reaches. Published studies support the conclusion that uptake can substantially change stream nutrient concentrations. On the other hand, there is little published evidence that mineralization also affects nutrient concentrations. Also, there is little information on direct microbial utilization of nutrients contained in the decaying leaves themselves. Our results suggest several directions for research that will improve our understanding of the complex relationship between leaf decay and nutrient dynamics in streams. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Modelling of Campylobacter survival in frozen chicken meatJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2007M. Ritz Abstract Aims:, To model the survival kinetics of Campylobacter jejuni on frozen chicken meat. Methods and Results:, Three different types of chicken meat surface (skin, skinned muscle and cut muscle) were inoculated with stationary phase cells of C. jejuni (8 log10 CFU cm,2) and frozen for 5 weeks at ,20°C. Bacterial numbers were determined weekly using two different methods of enumeration to quantify uninjured and injured cells. Analysis of variance of the results showed that the type of chicken surface and the method used to enumerate surviving cells were the most significant sources of variations in the numbers recovered (P < 0·0001), much more than the freezing time. To identify an appropriate model for the description of effects of freezing on survival over time, several models were fitted to the count data. Decay was found to be nonlinear. In general, survival was least on skin, better on skinned muscle and best on cut muscle. After 2 weeks, additional inactivation by freezing appeared to be negligible. Conclusion:, Because of the variability of survival it was not possible to fit and select a general model useful for all the different surfaces types. Significance and Impact of the Study:, The injured state of the cells leads to variability and the underestimation of bacterial survival. This is an essential factor for the assessment of Campylobacter -associated risk. [source] Attachment, decay, and social networkJOURNAL OF ORGANIZATIONAL BEHAVIOR, Issue 6 2001Ronald S. Burt To study decay in attachment to an organization, I analyse data on women who obtained an MBA from the University of Chicago's Graduate School of Business (GSB). I measure attachment in terms of network embedding: an alumna is attached to the GSB to the extent that people close to her graduated from the GSB. Behavioral data corroborate the network data in that alumnae measured to be more attached are more likely to have joined an alumni club and made a financial contribution to the school. The hypothesis is that alumnae attachment will decay over time, more slowly when the school is deeply embedded in an alumna's network, more quickly when disruptive events compete for the alumna's time and energy. As expected, attachment declines across the years after graduation (linearly for the first 20 years to about half its initial level), and decay is inhibited when connections with GSB graduates are embedded in stable relations of family, work, or long-term friendship. Decay is remarkably robust to events after graduation (which account for only 2 per cent of explained variance in attachment). In other words, an alumna's attachment today was largely determined while she was in school. The results should be of practical value to people who design programmes to build personal attachment to organizations, and of theoretical interest to scholars who study such connections. Copyright © 2001 John Wiley & Sons, Ltd. [source] Acetic Acid, Ethanol and Steam Effects on the Growth of Botrytis cinerea in vitro and Combination of Steam and Modified Atmosphere Packaging to Control Decay in KiwifruitJOURNAL OF PHYTOPATHOLOGY, Issue 2 2009Anastasia L. Lagopodi Abstract The effects of acetic acid fumigation, ethanol fumigation, and steam heat treatment on growth of Botrytis cinerea in vitro were investigated. The effect of steam heat treatments in combination with modified atmosphere packaging (MAP) on Botrytis decay development on ,Hayward' kiwifruit was also studied. The fungus was grown in Petri dishes on potato dextrose agar. Ethanol fumigation with 100 ,l/l for 3 or 6 min, or 200 ,l/l for 6 min enhanced the growth of B. cinerea. The effect of acetic acid on growth of B. cinerea was time and dosage-dependent. Fumigation with 1 ,l/l for 6 min, 2 ,l/l for 3 min, and 4 ,l/l for 3 min promoted radial growth of the fungus when compared to the growth of the untreated control. Fumigation with 2 ,l/l for 6 min delayed the growth of the fungus for the first 6 days, while fumigation with 6 ,l/l for 3 min delayed the growth of the fungus after the sixth day. Fumigation with 4 or 6 ,l/l acetic acid for 6 min, and 8 ,l/l acetic acid for 3 or 6 min resulted in complete inhibition of fungal growth. Steam heat treatment at 45°C for 6 min, and at 48, 51, and 54°C for 3 or 6 min completely inhibited fungal growth in vitro. Furthermore, steam treatments at 47, 50, and 53°C for 3 or 6 min completely inhibited decay at the stem end of kiwifruit kept at 10°C in MAP for 12 days. However, none of the steam treatments inhibited decay in wounds on the surface of the fruit kept in MAP. [source] Triads in Services Outsourcing: Bridge, Bridge Decay and Bridge Transfer,JOURNAL OF SUPPLY CHAIN MANAGEMENT, Issue 3 2009MEI LI Typically, a triad of actors is involved in any outsourcing situation: the buyer, the supplier and the buyer's customer. In manufacturing, the buyer acts as a bridge between its supplier and its customer and maintains this bridge position before, during and after the outsourcing. However, in services, the relationship structures among the three actors change before, during and after the outsourcing. Before outsourcing (i.e., during the contract negotiation stage), the buyer is the "bridge" between its supplier and its customer. During implementation, this bridge position begins to "decay" as its supplier comes in direct contact with the buyer's customer. Post-implementation, the bridge position is intended to be "transferred" to the supplier. However, if left unmanaged, this state of transferred bridge position has serious performance implications for the buyer. The supplier is now the bridge and thus enjoys the leverage inherent in being a bridge. This point has been missed in many services outsourcing ventures by major multinational corporations. To mitigate this effect, we propose that the buyer should continue to actively interact with its customer and closely monitor the supplier in order to prevent the supplier from solidifying its bridge position. [source] Messianic Power and Satanic Decay: Milton in Moby-DickLEVIATHAN, Issue 1-2 2002LESLIE E. SHELDON [source] Decay in time for a one-dimensional two-component plasmaMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 18 2008Robert Glassey Abstract The motion of a collisionless plasma is described by the Vlasov,Poisson (VP) system, or in the presence of large velocities, the relativistic VP system. Both systems are considered in one space and one momentum dimension, with two species of oppositely charged particles. A new identity is derived for both systems and is used to study the behavior of solutions for large times. Copyright © 2008 John Wiley & Sons, Ltd. [source] Organicism, Form and Structural Decay: Nielsen's Second Violin SonataMUSIC ANALYSIS, Issue 2 2002Daniel Grimley First page of article [source] Decay of multiple species of seagrass detritus is dominated by species identity, with an important influence of mixing littersOIKOS, Issue 2 2006Tim N. Moore No studies of seagrass decay have examined effects of the number of species contained within the detrital pool. Given the importance of decay for nutrient cycling and long-term productivity, we tested how three seagrass species affected decay in litterbags. Experimental results clearly showed that species identity was the predominant driver of mass loss, with total loss not differing between bags containing one, two and three species. Furthermore, we show there were also non-additive effects of mixing litter that were not predicted from single-species decay rates. The nature of the non-predictable mass loss varied both through time and with the number of species in the mixtures. This indicates that species richness indeed plays a role in this important ecosystem function but one that is of less importance than species identity. The concordance of these results with terrestrial studies suggests that mechanisms responsible for mixed-species decay rates may be broadly applicable across ecosystems. [source] Linear Radiofrequency Microcatheter Ablation Guided by Phased Array Intracardiac Echocardiography Combined with Temperature DecayPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2009DAVID KEANE M.D., Ph.D. Background:Fluoroscopy-guided catheter placement is limited in its ability to determine electrode-endocardial contact and involves radiation exposure. We hypothesized that (1) intracardiac echocardiography (ICE) would provide superior assessment of linear electrode contact compared to fluoroscopy and (2) slow temperature decay upon discontinuation of the radiofrequency current (time for temperature to fall 90% after a 10-second test application of the radiofrequency current T90) would indicate optimal electrode-myocardial contact. Methods:Sixty endocardial lesions were created in the atria and ventricles of six goats by simultaneous delivery of the radiofrequency current through two linear electrodes of a microcatheter with a central interelectrode thermocouple. Catheter placement was guided by fluoroscopy. A 7.5-MHz ICE transducer in the right atrium or ventricle assessed electrode contact. T90 and previously reported parameters of electrode contact and lesion formation were recorded. Histomorphometry was performed on the lesions. Results:T90 was 4.27 ± 4.98 seconds. Lesion depth significantly correlated with ICE assessment of electrode contact (r = 0.56, P = 0.001); T90 upon radiofrequency current offset (r = 0.48, P = 0.008), impedance fall upon radiofrequency current onset (r = 0.37, P = 0.008), bipolar pacing threshold preablation (r =,0.56, P = 0.001), bipolar electrogram amplitude preablation (r = 0.43, P = 0.02), but not with fluoroscopic assessment of the electrode contact (r = 0.18, n.s.). For the prediction of achieving a lesion depth of >2 mm, a T90 of >4.0 seconds yielded a specificity of 86% and a sensitivity of 52%, ICE yielded a specificity and sensitivity of 58% and 68%, respectively, while the specificity and sensitivity of fluoroscopy were 26% and 68%, respectively. Both ICE and T90 provide additional clinical relevance during guidance of cardiac microcatheter ablation. [source] Modeling, Analysis, and Simulation of Biofilm Formation and DecayPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003HJ Eberl Dr. In this article, we give a brief overview of our recent work on continuum mechanical modelling and simulation of microbial films. This comprises some classical tasks of applied mathematics such as computational fluid dynamics, analysis of partial differential equations, and mathematical biology. [source] Evolution and modulation of intracellular calcium release during long-lasting, depleting depolarization in mouse muscleTHE JOURNAL OF PHYSIOLOGY, Issue 19 2008Leandro Royer Intracellular calcium signals regulate multiple cellular functions. They depend on release of Ca2+ from cellular stores into the cytosol, a process that in many types of cells appears to be tightly controlled by changes in [Ca2+] within the store. In contrast with cardiac muscle, where depletion of Ca2+ in the sarcoplasmic reticulum is a crucial determinant of termination of Ca2+ release, in skeletal muscle there is no agreement regarding the sign, or even the existence of an effect of SR Ca2+ level on Ca2+ release. To address this issue we measured Ca2+ transients in mouse flexor digitorum brevis (FDB) skeletal muscle fibres under voltage clamp, using confocal microscopy and the Ca2+ monitor rhod-2. The evolution of Ca2+ release flux was quantified during long-lasting depolarizations that reduced severely the Ca2+ content of the SR. As in all previous determinations in mammals and non-mammals, release flux consisted of an early peak, relaxing to a lower level from which it continued to decay more slowly. Decay of flux in this second stage, which has been attributed largely to depletion of SR Ca2+, was studied in detail. A simple depletion mechanism without change in release permeability predicts an exponential decay with time. In contrast, flux decreased non-exponentially, to a finite, measurable level that could be maintained for the longest pulses applied (1.8 s). An algorithm on the flux record allowed us to define a quantitative index, the normalized flux rate of change (NFRC), which was shown to be proportional to the ratio of release permeability P and inversely proportional to Ca2+ buffering power B of the SR, thus quantifying the ,evacuability' or ability of the SR to empty its content. When P and B were constant, flux then decayed exponentially, and NFRC was equal to the exponential rate constant. Instead, in most cases NFRC increased during the pulse, from a minimum reached immediately after the early peak in flux, to a time between 200 and 250 ms, when the index was no longer defined. NFRC increased by 111% on average (in 27 images from 18 cells), reaching 300% in some cases. The increase may reflect an increase in P, a decrease in B, or both. On experimental and theoretical grounds, both changes are to be expected upon SR depletion. A variable evacuability helps maintain a constant Ca2+ output under conditions of diminishing store Ca2+ load. [source] Decay of a cut-off low and contribution to stratosphere-troposphere exchangeTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 564 2000H. Gouget Abstract We present a case study of the decay of a cut-off low over north-west Europe in June 1996, to establish how the stratospheric air initially contained within it was transferred to the troposphere. Two mechanisms for stratosphere-troposphere exchange are examined: direct convective erosion of the base of the low, and filamentation of the outer layers of the low along the flank of the polar jet stream. The approach taken relies on a combination of in-situ ozone and humidity measurements by MOZAIC (Measurement of Ozone and water vapour by Airbus In-service aircraft) aircraft and ozonesondes, and the European Centre for Medium-Range Weather Forecasts analyses. MOZAIC ozone is used to choose two analyses eight days apart at the genesis (14 June 1996) and decay (22 June 1996) of the low which have a consistent ozone/potential-vorticity relationship. Trajectories (both isentropic and three dimensional (3D)) between these two analyses reveal a consistent pattern; at the base of the low (310 K, 450 mb) all the trajectories attain tropospheric PV values whereas, at 320 K, those trajectories that leave the low experience a decrease in PV and those that do not leave the low retain their initial PV. We propose that air parcels leaving the low were stretched into thin filaments along the flank of the jet stream, which made them vulnerable to 3D mixing. A MOZAIC flight on 21 June 1996 provides direct evidence for this process. Up to 22 June 1996 (by which time the low had lost its closed circulation) the satellite images showed very little convection beneath the corresponding PV anomaly. Mixing was only effective at the very base of the stratospheric air at 310 K. On 22 June the remaining remnant of high PV was advected into a region of deep convection over central and eastern Europe, mixing the remaining stratospheric air into the troposphere. Of the initial mass of 1015 kg of stratospheric air contained in the low, 6 × 1014 kg was stripped into filaments along the jet and 4 × 1014 kg remained to be mixed by convection during the period 22,23 June 1996. [source] Distance Decay of Tree Species Similarity in Protected Areas on Terra Firme Forests in Colombian AmazoniaBIOTROPICA, Issue 5 2009Álvaro Duque ABSTRACT In this study, we investigated the pattern of floristic similarity as a function of geographical distances and environmental variability in well-drained uplands (terra firme) in Colombian Amazonia. The study site comprised three National Natural Parks, Tinigua, Chiribiquete, and Amacayacu, located in different geological units that represent a soil fertility gradient linked to parental materials. Differences in species richness between sites were compared using rarefaction analysis. A clear floristic transition appeared in the east,west direction following a soil fertility gradient along the first PCoA axis. In multiple regression analyses based on distance matrices, both geographical distances and geology explained 64 percent of the total floristic variation. Geographical distances alone accounted for 12 percent of variation in floristic similarities among plots, while geology alone accounted for 1 percent, and the joint effect of both explained 51 percent of the floristic variation. The species richness trend supports the existence of a latitudinal corridor southward of the geographical Equator in the Amazon basin, where tree diversity reaches the maximum expected values. A coupled effect of stochastic dispersal limitation and habitat specialization would certainly appear to be an appropriate explanation for tree species turnover in terra firme forests in Colombian Amazonia, strongly emphasizing that competition and neutrality must be supplementary rather than mutually exclusive processes. This result pinpoints the effect of dispersal on floral mixing as an ongoing active process for structuring tree communities in NW Amazonia, and the size of the reserves as a relevant issue to protect rare species from extinction by chance. [source] Decay of correlations and the central limit theorem for meromorphic mapsCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 5 2006Tien-Cuong Dinh Let f be a dominant meromorphic self-map of large topological degree on a compact Kähler manifold. We give a new construction of the equilibrium measure , of f and prove that , is exponentially mixing. As a consequence, we get the central limit theorem in particular for Hölder-continuous observables, but also for noncontinuous observables. © 2005 Wiley Periodicals, Inc. [source] Kinetics of the reactions of C2H5, n -C3H7, and n -C4H9 radicals with Cl2 at the temperature range 190,360 KINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 11 2007Arkke J. Eskola The kinetics of the C2H5 + Cl2, n -C3H7 + Cl2, and n -C4H9 + Cl2 reactions has been studied at temperatures between 190 and 360 K using laser photolysis/photoionization mass spectrometry. Decays of radical concentrations have been monitored in time-resolved measurements to obtain reaction rate coefficients under pseudo-first-order conditions. The bimolecular rate coefficients of all three reactions are independent of the helium bath gas pressure within the experimental range (0.5,5 Torr) and are found to depend on the temperature as follows (ranges are given in parenthesis): k(C2H5 + Cl2) = (1.45 ± 0.04) × 10,11 (T/300 K),1.73 ± 0.09 cm3 molecule,1 s,1 (190,359 K), k(n -C3H7 + Cl2) = (1.88 ± 0.06) × 10,11 (T/300 K),1.57 ± 0.14 cm3 molecule,1 s,1 (204,363 K), and k(n -C4H9 + Cl2) = (2.21 ± 0.07) × 10,11 (T/300 K),2.38 ± 0.14 cm3 molecule,1 s,1 (202,359 K), with the uncertainties given as one-standard deviations. Estimated overall uncertainties in the measured bimolecular reaction rate coefficients are ±20%. Current results are generally in good agreement with previous experiments. However, one former measurement for the bimolecular rate coefficient of C2H5 + Cl2 reaction, derived at 298 K using the very low pressure reactor method, is significantly lower than obtained in this work and in previous determinations. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 614,619, 2007 [source] Monitoring Protein Interactions in the Living Cell Through the Fluorescence Decays of the Cyan Fluorescent ProteinCHEMPHYSCHEM, Issue 7 2006Regis Grailhe Dr. Abstract Using fluorescence lifetime microspectroscopy and imaging techniques, we have studied the fluorescence of cyan fluorescent protein (CFP) transiently expressed in HEK-293 cells, in the presence or absence of its fluorescence resonance energy transfer (FRET) partner, yellow fluorescent protein (YFP). When the two proteins are attached through a 27-amino-acid linker, a 33,% average efficiency of intramolecular energy transfer is accurately determined inside the cell. Additionally, we observe a systematic quenching of the CFP fluorescence with increasing levels of protein expression. This quenching cannot be accounted for by formation of the previously described dimer of GFP-related proteins, since its magnitude is unchanged when the fluorescent proteins carry the mutation A206K shown to dissociate this dimer in vitro. Even when the intracellular protein concentration largely exceeds the in vitro dissociation constant of the dimer, self-association remains undetectable, either between free proteins or intramolecularly within the CFP,YFP construct. Instead, the detailed concentration effects are satisfactorily accounted for by a model of intermolecular, concentration-dependent energy transfer, arising from molecular proximity and crowding. In the case of CFP alone, we suggest that self-quenching could result from a pseudo-homo FRET mechanism between different, spectrally shifted emissive forms of the protein. These phenomena require careful consideration in intracellular FRET studies. [source] NMR and the uncertainty principle: How to and how not to interpret homogeneous line broadening and pulse nonselectivity.CONCEPTS IN MAGNETIC RESONANCE, Issue 5 2008IV. (Un?)certainty Abstract Following the treatments presented in Parts I, II, and III, I herein address the popular notion that the frequency of a monochromatic RF pulse as well as that of a monochromatic FID is "in effect" uncertain due to the (Heisenberg) Uncertainty Principle, which also manifests itself in the fact that the FT-spectrum of these temporal entities is spread over a nonzero frequency band. I will show that the frequency spread should not be interpreted as "in effect" meaning a range of physical driving RF fields in the former, and "spin frequencies" in the latter case. The fact that a shorter pulse or a more quickly decaying FID has a wider FT-spectrum is in fact solely due to the Fourier Uncertainty Principle, which is a less well known and easily misunderstood concept. A proper understanding of the Fourier Uncertainty Principle tells us that the FT-spectrum of a monochromatic pulse is not "broad" because of any "uncertainty" in the RF frequency, but because the spectrum profile carries all of the pulse's features (frequency, phase, amplitude, length, temporal location) coded into the complex amplitudes of the FT-spectrum's constituent eternal basis harmonic waves. A monochromatic RF pulse's capability to excite nonresonant magnetizations is in fact a purely classical off-resonance effect that has nothing to do with "uncertainty". Analogously, "Lorentzian lineshape" means exactly the same thing physically as "exponential decay," and all inferences as to the physical reasons for that decay must be based on independent assumptions or observations. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part A 32A: 373,404, 2008. [source] On the inversion of multicomponent NMR relaxation and diffusion decays in heterogeneous systemsCONCEPTS IN MAGNETIC RESONANCE, Issue 2 2005Raffaele Lamanna Abstract The analysis of the decay of NMR signals in heterogeneous samples requires the solution of an ill-posed inverse problem to evaluate the distributions of relaxation and diffusion parameters. Laplace transform is the most widely accepted algorithm used to describe the NMR decay in heterogeneous systems. In this article we suggest that a superposition of Fredholm integrals, with different kernels, is a more suitable model for samples in which liquid and solid-like phases are both present. In addition, some algorithms for the inversion of Laplace and Fredholm inverse problems are illustrated. The quadrature methods and regularization function in connection with the use of nonlinear discretization grids are also discussed. The described inversion algorithms are tested on simulated and experimental data, and the role of noise is discussed. © 2005 Wiley Periodicals, Inc. Concepts Magn Reson Part A 26A: 78,90, 2005 [source] Effect of Oscillating Sheath on Near-Wall Electron Current Profile in Hall ThrustersCONTRIBUTIONS TO PLASMA PHYSICS, Issue 9-10 2008D. R. Yu Abstract The radial profile of the axial electron current in Hall thrusters was measured; however, the significant decay of the current density peak in the near-wall region can't be explained effectively by the steady sheath theory. As the sheath exhibits an oscillating character when the thruster is in operation, its effect on the near-wall current profile has been studied in this paper. To obtain a comprehensive knowledge, we have considered a wide sheath oscillation frequency span which includes two asymptotic frequency cases at high and low ends. Based on the case studied, either an analytical treatment or a numerical simulation is applied. The results show that the current density peak has a fastest damping speed away from the wall at the asymptotic low frequency. With the increase of the frequency, both the decay and the spatial "wavelength" of the current profile decrease. The decay finally disappears at the asymptotic high frequency with a constant spatial "wavelength". Moreover, the sheath oscillation amplitude can enhance the decay and enlarge the spatial "wavelength". Taking into account of the realistic situation in Hall thrusters, the significant impact of the oscillating sheath on the near-wall electron current profiles can be anticipant. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High Density Cascaded Arc Produced Plasma Expanding in a Low Pressure RegionCONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2004R. P. Dahiya Abstract Experimental measurements made in thermal expanding argon, nitrogen and hydrogen plasmas with particular reference to molecular kinetics, surface nitriding and intense flux in magnetic field are discussed. The plasma is generated in a cascaded arc source. In the presence of molecular species (H2 / N2) dissociative recombination reactions involving rovibrationally excited molecules contribute to a rapid decay of the plasma species, especially for hydrogen system. A combination of nitrogen and hydrogen plasma gives an efficient plasma nitriding process, which has been applied for case hardening of machinery components. In another setup a strong axial magnetic field (0.4 - 1.6 T) contains and substantially prolongs the plasma beam in the chamber. In the presence of the magnetic field, an additional current drawn through the plasma beam using a biased substrate and a ring creates dense low temperature plasma giving a new unexplored plasma regime. The plasma kinetics are modified in this regime from the recombining to the ionising mode. When the additional current in the argon plasma beam exceeds 30 A, its light emission is predominantly in the blue region. With the additional current and magnetic field, the emission intensity of H, and other lines arising from higher energy levels in the hydrogen Balmer series is enhanced. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Laser plasma plume kinetic spectroscopy of the nitrogen and carbon speciesCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7 2003Z. Zelinger Abstract The formation and decay of carbon and nitrogen atoms, CN radicals and C2 molecules were monitored using spatial- and time-resolved emission spectroscopy in a plasma plume formed during laser ablation of a graphite target in nitrogen atmosphere. A simple exponential model was used to explain the effect of the individual chemical reactions and plasma dynamics on the measured kinetic characteristics. The succession of emissions C , N , CN was observed in the time-resolved spectra, supporting the suggestion that the CN radical is formed mainly by the direct reaction C + N , CN or C2 + N2 , 2CN. The formation of CN radical was enhanced by the additional generation of atomic nitrogen through the RF discharge. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Severing of F-actin by yeast cofilin is pH-independentCYTOSKELETON, Issue 9 2006Dmitry Pavlov Abstract Cofilin plays an important role in actin turnover in cells by severing actin filaments and accelerating their depolymerization. The role of pH in the severing by cofilin was examined using fluorescence microscopy. To facilitate the imaging of actin filaments and to avoid the use of rhodamine phalloidin, which competes with cofilin, ,-actin was labeled with tetramethylrhodamine cadaverine (TRC) at Gln41. The TRC-labeling inhibited actin treadmilling strongly, as measured by ,ATP release. Cofilin binding, detected via an increase in light scattering, and the subsequent conformational change in filament structure, as detected by TRC fluorescence decay, occurred 2,3 times faster at pH 6.8 than at pH 8.0. In contrast, actin filaments severing by cofilin was pH-independent. The pH-independent severing by cofilin was confirmed using actin labeled at Cys374 with Oregon Green® 488 maleimide. The depolymerization of actin by cofilin was faster at high pH. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source] The interaction of age and unconditioned stimulus intensity on long-trace conditioned flavor aversion in ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2002James R. Misanin Abstract To see if the neural representation of the conditioned stimulus (CS) is available to old-age rats beyond the time it is available to young adults, the intensity of the unconditioned stimulus (US) and the length of the CS,US interval were systematically varied in a trace conditioning experiment. Results indicated that increasing US intensity extends the interval over which trace conditioning is evident in old-age rats but not in young adults, suggesting that trace decay occurs more rapidly in young rats. Results were interpreted in terms of age differences in the workings of hypothesized biochemical timing mechanisms that may directly influence the ability to associate stimuli over trace intervals in conditioned taste-aversion procedures. © 2002 Wiley Periodicals, Inc. Dev Psychobiol 40: 131,137, 2002. DOI 10.1002/dev.10018 [source] Scale-dependent controls upon the fluvial export of large wood from river catchmentsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2009Jung Il Seo Abstract The annual fluvial export of large wood (LW) was monitored by local reservoir management offices in Japan. LW export per unit watershed area was relatively high in small watersheds, peaked in intermediate watersheds, and decreased in large watersheds. To explain these variations, we surveyed the amount of LW with respect to channel morphology in 78 segments (26 segments in each size class) in the Nukabira River, northern Japan. We examined the differences in LW dynamics, including its recruitment, transport, storage, and fragmentation and decay along the spectrum of watershed sizes. We found that a large proportion of LW produced by forest dynamics and hillslope processes was retained because of the narrower valley floors and lower stream power in small watersheds. The retained LW pieces may eventually be exported during debris flows. In intermediate watersheds, the volume of LW derived from hillslopes decreased substantially with reductions in the proportion of channel length bordered by hillslope margins, which potentially deliver large quantities of LW. Because these channels have lower wood piece length to channel width ratios and higher stream power, LW pieces can be transported downstream. During transport, LW pieces are further fragmented and can be more easily transported. Therefore, the fluvial export of LW is maximized in intermediate watersheds. Rivers in large watersheds, where the recruitment of LW is limited by the decreasing hillslope margins, cannot transport LW pieces because of their low stream power, and thus LW pieces accumulate at various storage sites. Although these stored LW pieces can be refloated and transported by subsequent flood events, they may also become trapped by obstacles such as logjams and standing trees on floodplains and in secondary channels, remaining there for decades and eventually decaying into fine organic particles. Thus, the fluvial export of LW pieces is low in large watersheds. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||