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Derivation
Kinds of Derivation Terms modified by Derivation Selected AbstractsDerivation of Recovery Kinetics From Stress Relaxation Tests,ADVANCED ENGINEERING MATERIALS, Issue 3 2010Sheila Bhaumik The recovery behavior of a commercial aluminum alloy 3103 was investigated by the means of two alternative experimental methods: stress relaxation (SR) and double tension tests (DT). In case of SR, the stress,time evolution after deformation was recorded, and for DT the yield stress after several recovery times were measured. The DT tests were further sub-divided into tests with and without external load during recovery. The results revealed that the recovery kinetics is clearly accelerated by the external stress during the SR. However, the difference between the DT and SR stresses is much larger. It is caused by continued dislocation glide after the deformation, which causes continued plastic elongation of the specimens. This is demonstrated quantitatively by appropriate evaluation models for both experiments. In contrast to DT, the SR evaluation accounts for the elastic SR due to plastic elongation, but the recovery parameters are the same ones as for DT. This makes it possible to replace DT by SR experiments, which are materially less laborious. [source] Carp (Cyprinus carpio) as a powerful invader in Australian waterwaysFRESHWATER BIOLOGY, Issue 7 2004John D. Koehn Summary 1. The invasion of carp (Cyprinus carpio L.) in Australia illustrates how quickly an introduced fish species can spread and dominate fish communities. This species has become the most abundant large freshwater fish in south-east Australia, now distributed over more than 1 million km2. 2. Carp exhibit most of the traits predicted for a successful invasive fish species. In addition, degradation of aquatic environments in south-east Australia has given them a relative advantage over native species. 3. Derivation of relative measures of 13 species-specific attributes allowed a quantitative comparison between carp and abundant native fish species across five major Australian drainage divisions. In four of six geographical regions analysed, carp differed clearly from native species in their behaviour, resource use and population dynamics. 4. Climate matching was used to predict future range expansion of carp in Australia. All Australian surface waters appear to be climatically suitable for carp. 5. This assessment strongly reinforces the need for immediate management of carp in Australia to include targeted control of human-assisted dispersal, such as use of carp as bait by anglers, distribution to new locations by anglers and the use of the ,Koi' strain in the aquarium industry. 6. Given their historical spread, dispersal mechanisms and ecological requirements, the expansion of carp across most of the remainder of Australia is to be expected. [source] Derivation, characterization, and phenotypic variation of hepatic progenitor cell lines isolated from adult ratsHEPATOLOGY, Issue 2 2002Li Yin Liver progenitor cells (LPCs) cloned from adult rat livers following allyl alcohol injury express hematopoietic stem cell and early hepatic lineage markers when cultured on feeder layers; under these conditions, neither mature hepatocyte nor bile duct, Ito, stellate, Kupffer cell, or macrophage markers are detected. These phenotypes have remained stable without aneuploidy or morphological transformation after more than 100 population doublings. When cultured without feeder layers, the early lineage markers disappear, and mature hepatocyte markers are expressed; mature hepatocytic differentiation and cell size are also augmented by polypeptide and steroidal growth factors. In contrast to hepatocytic potential, duct-like structures and biliary epithelial markers are expressed on Matrigel. Because they were derived without carcinogens or mutagens, these bipotential LPC lines provide novel tools for models of cellular plasticity and hepatocarcinogenesis, as well as lines for use in cellular transplantation, gene therapy, and bioreactor construction. [source] Power function decay of hydraulic conductivity for a TOPMODEL-based infiltration routineHYDROLOGICAL PROCESSES, Issue 18 2006Jun Wang Abstract TOPMODEL rainfall-runoff hydrologic concepts are based on soil saturation processes, where soil controls on hydrograph recession have been represented by linear, exponential, and power function decay with soil depth. Although these decay formulations have been incorporated into baseflow decay and topographic index computations, only the linear and exponential forms have been incorporated into infiltration subroutines. This study develops a power function formulation of the Green and Ampt infiltration equation for the case where the power n = 1 and 2. This new function was created to represent field measurements in the New York City, USA, Ward Pound Ridge drinking water supply area, and provide support for similar sites reported by other researchers. Derivation of the power-function-based Green and Ampt model begins with the Green and Ampt formulation used by Beven in deriving an exponential decay model. Differences between the linear, exponential, and power function infiltration scenarios are sensitive to the relative difference between rainfall rates and hydraulic conductivity. Using a low-frequency 30 min design storm with 4·8 cm h,1 rain, the n = 2 power function formulation allows for a faster decay of infiltration and more rapid generation of runoff. Infiltration excess runoff is rare in most forested watersheds, and advantages of the power function infiltration routine may primarily include replication of field-observed processes in urbanized areas and numerical consistency with power function decay of baseflow and topographic index distributions. Equation development is presented within a TOPMODEL-based Ward Pound Ridge rainfall-runoff simulation. Copyright © 2006 John Wiley & Sons, Ltd. [source] Preliminary Derivation of a Nursing Home Confusion Assessment Method Based on Data from the Minimum Data SetJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 7 2007David Dosa MD OBJECTIVES: To develop a Nursing Home Confusion Assessment Method (NH-CAM) for diagnosing delirium using items found on the Minimum Data Set (MDS) and to compare its performance with that of the delirium Resident Assessment Protocol (RAP) trigger and to an additive score of six of the RAP items. DESIGN: Retrospective cohort study using MDS and Medicare claims data. SETTING: Free-standing NHs in urban markets in the 48 contiguous U.S. states. PARTICIPANTS: Long-stay residents who returned to their NHs after acute hospitalizations between April and September 2000 (N=35,721). MEASUREMENTS: Mortality and rehospitalization rates within 90 days of readmission to the NH from the hospital. RESULTS: Almost one-third (31.8%) of the residents were identified as having delirium according to the RAP; 1.4% had full delirium, 13.2% had Subsyndromal II delirium, and 17.2% had Subsyndromal I delirium. More-severe NH-CAM scores were associated with greater risks of mortality and rehospitalization. NH-CAM levels were strong independent risk factors for survival and rehospitalization in a Cox model (hazard ratios ranging from 1.5 to 1.9 for mortality and 1.1 to 1.3 for rehospitalization) adjusting for cognitive and physical function, diagnoses, inpatient care parameters, care preferences, and sociodemographic factors. CONCLUSION: The NH-CAM successfully stratified NH residents' risk of mortality and rehospitalization. If validated clinically, the NH-CAM may be useful in care planning and in further research on the determinants and consequences of delirium in the NH. [source] Derivation of the mammalian skull vaultJOURNAL OF ANATOMY, Issue 1-2 2001GILLIAN M. MORRISS-KAY abstract This review describes the evolutionary history of the mammalian skull vault as a basis for understanding its complex structure. Current information on the developmental tissue origins of the skull vault bones (mesoderm and neural crest) is assessed for mammals and other tetrapods. This information is discussed in the context of evolutionary changes in the proportions of the skull vault bones at the sarcopterygiantetrapod transition. The dual tissue origin of the skull vault is considered in relation to the molecular mechanisms underlying osteogenic cell proliferation and differentiation in the sutural growth centres and in the proportionate contributions of different sutures to skull growth. [source] Analyses of Digman's Child-Personality Data: Derivation of Big-Five Factor Scores From Each of Six SamplesJOURNAL OF PERSONALITY, Issue 5 2001Lewis R. Goldberg One of the world's richest collections of teacher descriptions of elementary-school children was obtained by John M. Digman from 1959 to 1967 in schools on two Hawaiian islands. In six phases of data collection, 88 teachers described 2,572 of their students, using one of five different sets of personality variables. The present report provides findings from new analyses of these important data, which have never before been analyzed in a comprehensive manner. When factors developed from carefully selected markers of the Big-Five factor structure were compared to those based on the total set of variables in each sample, the congruence between both types of factors was quite high. Attempts to extend the structure to 6 and 7 factors revealed no other broad factors beyond the Big Five in any of the 6 samples. These robust findings provide significant new evidence for the structure of teacher-based assessments of child personality attributes. [source] Biased estimates of nonrenal clearanceJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2001Peter H. Hinderling Abstract The goal of the investigation was to critically evaluate published values for oral nonrenal clearance and their postulated dependence on renal function with drugs administered orally to subjects with varying renal function. Derivation of the pertinent equations indicated that the values reported for oral nonrenal clearance tend to systematically overestimate both the true oral and intravenous nonrenal clearances of these drugs. Computations were performed to confirm these findings not only for subjects with normal renal function, but also for patients with renal impairment. The computations evaluated the relevance of bioavailability and renal clearance of a drug for the bias in the estimates of true oral or intravenous nonrenal clearance. The results of the computations showed that the estimates for true oral and intravenous nonrenal clearance derived from oral data exceed systematically the true values in subjects with normal or reduced renal function. Also, a renal function dependent decrease of the true oral or intravenous nonrenal clearance is falsely diagnosed if apparent oral nonrenal clearance values are used for the estimates. The magnitude of bioavailability and renal clearance impact the bias in the estimates derived from oral data. For drugs with predominant renal excretion and small bioavailability the bias is largest. For drugs with predominant nonrenal elimination and large bioavailability the bias is smallest. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:960,966, 2001 [source] Computer Algebra Derivation of the Bias of Linear Estimators of Autoregressive ModelsJOURNAL OF TIME SERIES ANALYSIS, Issue 2 2006Y. Zhang Abstract., A symbolic method which can be used to obtain the asymptotic bias and variance coefficients to order O(1/n) for estimators in stationary time series is discussed. Using this method, the large-sample bias of the Burg estimator in the AR(p) for p = 1, 2, 3 is shown to be equal to that of the least squares estimators in both the known and unknown mean cases. Previous researchers have only been able to obtain simulation results for the Burg estimator's bias because this problem is too intractable without using computer algebra. The asymptotic bias coefficient to O(1/n) of Yule,Walker as well as least squares estimates is also derived in AR(3) models. Our asymptotic results show that for the AR(3), just as in the AR(2), the Yule,Walker estimates have a large bias when the parameters are near the nonstationary boundary. The least squares and Burg estimates are much better in this situation. Simulation results confirm our findings. [source] Theoretical Derivation of the Molecular Weight Distribution of End-Capped Linear Condensation PolymersMACROMOLECULAR THEORY AND SIMULATIONS, Issue 1 2009Henk Knoester Abstract End-capped, low molecular weight polymers have found numerous practical applications. By providing the end-capper molecules with specific chemical functionality, the polymer material can be equipped with a desired chemical behavior for product application or polymer processing. Using probabilistic methods, formulas are derived for calculating the target molecular weight distribution and its averages for the case of linear condensation polymerization. The formulas are generally applicable, allowing for arbitrary amounts of monofunctional monomers or end-capper molecules affecting either one or both functional groups involved in the polymerization process. [source] Photosynthesis within isobilateral Eucalyptus pauciflora leavesNEW PHYTOLOGIST, Issue 4 2006John R. Evans Summary ,,Adult Eucalyptus pauciflora leaves are vertically displayed. They have multiple palisade cell layers beneath both surfaces, interrupted by numerous oil glands. Here, we characterized light absorption, chlorophyll, photosynthetic capacity and CO2 fixation profiles through these leaves. ,,Multiple chlorophyll fluorescence images of leaves viewed in cross-section were made by applying light from different directions. 14CO2 labelling, followed by paradermal cryosectioning, was used to measure profiles of photosynthesis. ,,Photosynthetic capacity peaked 75 µm into the mesophyll beneath each surface and was lowest in the centre of the 600-µm-thick leaf. Predictions by a multilayer model using Beer's law matched the observed profiles of 14C fixation. When constrained to the horizontal, a vertically acclimated leaf gains only 79% of the daily photosynthesis achieved by a horizontally acclimated leaf. However, it outperforms the horizontally acclimated leaf when both are oriented vertically. ,,Each half of the observed profile of photosynthetic capacity closely matches the profile of light absorption through the leaf with unilateral illumination to that surface. Derivation of biochemical parameters from gas exchange measured under unilateral illumination would underestimate the real photosynthetic capacity of these leaves by 21%. [source] Derivation, safety and efficacy of a Marek's disease vaccine developed from an Australian isolate of very virulent Marek's disease virusAUSTRALIAN VETERINARY JOURNAL, Issue 1 2002RC KARPATHY Objective To develop a serotype 1 Marek's disease (MD) vaccine from a very virulent MDV (vvMDV) pathotype and demonstrate safety and efficacy against early challenge with very virulent field strains in the presence of maternal antibody. Study design Strain BH 16 was isolated and attenuated by serial cell culture passage. One of two cloned passages was selected for vaccine development following early laboratory-scale protection trials in commercial birds. Comparative protection trials were carried out on the BH 16 vaccine and on a CVI 988 Rispens vaccine using commercial and SPF chickens. Challenge viruses used were either a low passage strain BH 16 virus, the Woodlands No. 1 strain or MPF 57 strain of MDV. The BH 16 vaccine was back-passaged in SPF chickens six times and virus recovered from the final passage and the original vaccine virus were tested for safety. The immunosuppressive potential of the BH 16 and Rispens vaccines was also assessed in parallel. Results The BH 16 and Rispens vaccines induced comparable levels of protection when used as monovalent or multi-valent vaccines, although protection achieved with the mono-valent vaccines was lower. No gross tumour formation was evident in any birds receiving the BH 16 vaccine or bird-passaged virus, although microscopic lesions were present in 2/12 birds that received the bird-passaged virus. In tests for immunosuppression, there was no histological evidence of damage to either the bursa of Fabricius or the thymus. Conclusion The BH 16 vaccine was shown to be safe and at least as protective as the Rispens vaccine against three highly virulent MD challenge viruses. [source] ZnO:Eu Thin-Films: Sol,Gel Derivation and Strong Photoluminescence from 5D0 , 7F0 Transition of Eu3+ Ions.CHEMINFORM, Issue 24 2007Peiliang Chen Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] An Expedient Route to 3-Chlorothioxanthen-9-one-10,10-dioxide and Derivation by Palladium-Catalyzed Coupling.CHEMINFORM, Issue 14 2007Pedro M. J. Lory Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Derivation of a Triage Algorithm for Chest Radiography of Community-acquired Pneumonia Patients in the Emergency DepartmentACADEMIC EMERGENCY MEDICINE, Issue 1 2008Demetrios N. Kyriacou MD Abstract Background:, Community-acquired pneumonia (CAP) accounts for 1.5 million emergency department (ED) patient visits in the United States each year. Objectives:, To derive an algorithm for the ED triage setting that facilitates rapid and accurate ordering of chest radiography (CXR) for CAP. Methods:, The authors conducted an ED-based retrospective matched case,control study using 100 radiographic confirmed CAP cases and 100 radiographic confirmed influenzalike illness (ILI) controls. Sensitivities and specificities of characteristics assessed in the triage setting were measured to discriminate CAP from ILI. The authors then used classification tree analysis to derive an algorithm that maximizes sensitivity and specificity for detecting patients with CAP in the ED triage setting. Results:, Temperature greater than 100.4°F (likelihood ratio = 4.39, 95% confidence interval [CI] = 2.04 to 9.45), heart rate greater than 110 beats/minute (likelihood ratio = 3.59, 95% CI = 1.82 to 7.10), and pulse oximetry less than 96% (likelihood ratio = 2.36, 95% CI = 1.32 to 4.20) were the strongest predictors of CAP. However, no single characteristic was adequately sensitive and specific to accurately discriminate CAP from ILI. A three-step algorithm (using optimum cut points for elevated temperature, tachycardia, and hypoxemia on room air pulse oximetry) was derived that is 70.8% sensitive (95% CI = 60.7% to 79.7%) and 79.1% specific (95% CI = 69.3% to 86.9%). Conclusions:, No single characteristic adequately discriminates CAP from ILI, but a derived clinical algorithm may detect most radiographic confirmed CAP patients in the triage setting. Prospective assessment of this algorithm will be needed to determine its effects on the care of ED patients with suspected pneumonia. [source] Technology and Context Within Research on International Development Programs: Positioning an Integrationist PerspectiveCOMMUNICATION THEORY, Issue 1 2003Renée Houston We focus on development efforts that use information and communication technologies for educational purposes in developing nations. The oppositional nature of the approaches to development makes constructive dialogue among theoretical perspectives difficult. Using Jackson's (1996) metatheoretical classification scheme, we sort development research based on 4 possible logical relationships between technology as an artifact and the social context. Derivation of the scheme is principled rather than historical and independent of any particular theory. Focusing on assumptions about technology and context brings new understanding of each perspective and can foster a dialogue across the perspectives. Further, we offer that self-organizing systems theory possesses the potential of representing an integrationist perspective in development research. [source] Determinants of the Willingness of Belgian Farmers to Participate in Agri-environmental MeasuresJOURNAL OF AGRICULTURAL ECONOMICS, Issue 3 2002Isabel Vanslembrouck This paper explores the willingness of Belgian farmers to participate in two voluntary agri-environmental policies. Farmers' contingent behaviour is analysed on the basis of survey data. Derivations based on a conceptual micro-economic model indicate that decision subject and decision maker characteristics are important for farmers' participation. The model is empirically tested through the specification and estimation of a probit model. Consistency is found between the theoretical framework and the empirical results indicating that both the expected effect on farm production and the farmers' environmental attitude, which is more positive among younger and better educated farmers, are significant determinants of the acceptance rate of agri-environmental policies. Other variables which influence participation decisions are farm size and previous experience of farmers themselves or of neighbouring farmers with agri-environmental measures. [source] A tutorial comparison of the NMRIT and LAOCOON approaches for analyses of complex solution-phase nuclear magnetic resonance spectraMAGNETIC RESONANCE IN CHEMISTRY, Issue 5 2002Stanley L. Manatt Abstract For spin ½ nuclei the two most frequently used iterative approaches for determinations of NMR chemical shifts (hi) and coupling constants (Ji), NMRIT and LAOCOON, are discussed. When multiple pulse techniques for extraction of these parameters fail or lead to complicated spectra in the cases of very strongly coupled spin systems and systems involving magnetically nonequivalent, chemical shift equivalent nuclei, recourse to these iterative methods is necessary. The former approach employs the energy levels derived from the observed transition frequencies, whereas the latter approach uses the observed transition frequencies. Derivations of the general iterative equations for both approaches are given, along with the specific equations for the ABC spin system. The matrix nature of the derivation of these equations is stressed. Also discussed is the modified NMRIT program, NMRENIT, which has major advantages over the former in cases with symmetry and in cases where not enough lines can be assigned to link all the energy levels. The advantages of the latter program over LAOCOON in certain cases are discussed. Some general advice on the use of both approaches is presented. The Hoffman energy level approach is also discussed and it is shown that it yields the same iterative equations as the LAOCOON approach. Copyright © 2002 John Wiley & Sons, Ltd. [source] Magnetohydrodynamic turbulence in a strongly magnetised plasmaASTRONOMISCHE NACHRICHTEN, Issue 1 2010S. Sridhar Abstract I present a review of incompressible magnetohydrodynamic (MHD) turbulence in a strongly magnetised plasma. The approach is phenomenological even where a more rigorous theory is available, so that a reader armed with paper, pencil and some determination may be able to work through most of the physics. The focus is on the inertial-range spectra for very large (fluid and magnetic) Reynolds numbers. These theories of the inertial-range are built on two important facts: (i) Kraichnan's insight that the turbulent cascades are a result of nonlinear interactions between oppositely directed wavepackets of Elsasser fields; (ii) these oppositely directed wavepackets do not exchange energy, but contribute only to changing each other's spatial structures. I begin with a description and critique of the Iroshnikov-Kraichnan theory, and explore the fundamental departures necessitated by the anisotropic nature of the turbulence. Derivations of the inertial-range spectra of four regimes of MHD turbulence , the balanced weak, balanced strong, imbalanced weak and the imbalanced strong cascades , are then presented. The need for studying the spectra of imbalanced turbulence when the waves on the outer scale have a short correlation time is briefly discussed (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Near-Term Travel Speed Prediction Utilizing Hilbert,Huang TransformCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 8 2009Khaled Hamad In this study, we propose an innovative methodology for such prediction. Because of the inherently direct derivation of travel time from speed data, the study was limited to the use of speed only as a single predictor. The proposed method is a hybrid one that combines the use of the empirical mode decomposition (EMD) and a multilayer feedforward neural network with backpropagation. The EMD is the key part of the Hilbert,Huang transform, which is a newly developed method at NASA for the analysis of nonstationary, nonlinear time series. The rationale for using the EMD is that because of the highly nonlinear and nonstationary nature of link speed series, by decomposing the time series into its basic components, more accurate forecasts would be obtained. We demonstrated the effectiveness of the proposed method by applying it to real-life loop detector data obtained from I-66 in Fairfax, Virginia. The prediction performance of the proposed method was found to be superior to previous forecasting techniques. Rigorous testing of the distribution of prediction errors revealed that the model produced unbiased predictions of speeds. The superiority of the proposed model was also verified during peak periods, midday, and night. In general, the method was accurate, computationally efficient, easy to implement in a field environment, and applicable to forecasting other traffic parameters. [source] The origins and present status of the radio wave controversy in NMRCONCEPTS IN MAGNETIC RESONANCE, Issue 4 2009D.I. Hoult Abstract The origins, history, and present status of the controversy surrounding a quantum description of the NMR signal as being due to radio waves are traced. With the Principle of Relativity and Coulomb's Law as formal starting points and the minimum of mathematics needed for understanding, the derivation of a classical electromagnetic theory of signal reception is first given. The agreement between that classical theory and a recent NMR experiment is then presented, leading to proof that, except for the highest field imaging experiments, there is no significant contribution of radio waves to the signal. Attention is drawn to the very different properties of the near and far energy, momenta, and fields inherent in the derivation. The role of the Correspondence Principle in formulating a quantum description is then emphasized and it is shown that the standard NMR interpretation of Dicke's theory of coherent spontaneous emission,that the latter is responsible for the NMR signal,cannot be correct. Finally, the author speculates on some of the intriguing relationships found in the classical electrodynamics of NMR signal reception and attempts to relate them to a common quantum electrodynamic precept of near field interaction: that the free induction decay voltage present at the terminals of an open-circuit receiving coil is based on an exchange of virtual photons between the nuclei in a sample and the free electrons in a receiving coil. © 2009 Crown in the right of Canada. Concepts Magn Reson Part A 34A: 193,216, 2009. [source] Physical foundations, models, and methods of diffusion magnetic resonance imaging of the brain: A reviewCONCEPTS IN MAGNETIC RESONANCE, Issue 5 2007Ludovico Minati Abstract The foundations and characteristics of models and methods used in diffusion magnetic resonance imaging, with particular reference to in vivo brain imaging, are reviewed. The first section introduces Fick's laws, propagators, and the relationship between tissue microstructure and the statistical properties of diffusion of water molecules. The second section introduces the diffusion-weighted signal in terms of diffusion of magnetization (Bloch,Torrey equation) and of spin-bearing particles (cumulant expansion). The third section is dedicated to the rank-2 tensor model, the bb -matrix, and the derivation of indexes of anisotropy and shape. The fourth section introduces diffusion in multiple compartments: Gaussian mixture models, relationship between fiber layout, displacement probability and diffusivity, and effect of the b -value. The fifth section is devoted to higher-order generalizations of the tensor model: singular value decompositions (SVD), representation of angular diffusivity patterns and derivation of generalized anisotropy (GA) and scaled entropy (SE), and modeling of non-Gaussian diffusion by means of series expansion of Fick's laws. The sixth section covers spherical harmonic decomposition (SHD) and determination of fiber orientation by means of spherical deconvolution. The seventh section presents the Fourier relationship between signal and displacement probability (Q -space imaging, QSI, or diffusion-spectrum imaging, DSI), and reconstruction of orientation-distribution functions (ODF) by means of the Funk,Radon transform (Q -ball imaging, QBI). © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part A 30A: 278,307, 2007. [source] Applying Network Analysis to the Conservation of Habitat Trees in Urban Environments: a Case Study from Brisbane, AustraliaCONSERVATION BIOLOGY, Issue 3 2006MONIKA RHODES conectividad de perchas; fauna que utiliza oquedades; planificación de la conservación; red sin escala; Tadarida australis Abstract:,In Australia more than 300 vertebrates, including 43 insectivorous bat species, depend on hollows in habitat trees for shelter, with many species using a network of multiple trees as roosts. We used roost-switching data on white-striped freetail bats (Tadarida australis; Microchiroptera: Molossidae) to construct a network representation of day roosts in suburban Brisbane, Australia. Bats were caught from a communal roost tree with a roosting group of several hundred individuals and released with transmitters. Each roost used by the bats represented a node in the network, and the movements of bats between roosts formed the links between nodes. Despite differences in gender and reproductive stages, the bats exhibited the same behavior throughout three radiotelemetry periods and over 500 bat days of radio tracking: each roosted in separate roosts, switched roosts very infrequently, and associated with other bats only at the communal roost. This network resembled a scale-free network in which the distribution of the number of links from each roost followed a power law. Despite being spread over a large geographic area (>200 km2), each roost was connected to others by less than three links. One roost (the hub or communal roost) defined the architecture of the network because it had the most links. That the network showed scale-free properties has profound implications for the management of the habitat trees of this roosting group. Scale-free networks provide high tolerance against stochastic events such as random roost removals but are susceptible to the selective removal of hub nodes. Network analysis is a useful tool for understanding the structural organization of habitat tree usage and allows the informed judgment of the relative importance of individual trees and hence the derivation of appropriate management decisions. Conservation planners and managers should emphasize the differential importance of habitat trees and think of them as being analogous to vital service centers in human societies. Resumen:,En Australia, más de 300 vertebrados, incluyendo 43 especies de murciélagos insectívoros, dependen de oquedades en árboles para refugiarse; muchas de ellas perchan en una red de múltiples árboles. Utilizamos datos de cambio de perchas en Tadarida australis (Microchiroptera: Molossidae) para construir una representación reticular de las perchas diurnas en los suburbios de Brisbane, Australia. Los murciélagos fueron capturados en un árbol con un grupo de varios cientos de individuos y liberados con transmisores. Cada percha utilizada por los murciélagos representó un nodo individual en la red, y los movimientos de murciélagos entre perchas constituyeron los eslabones entre los nodos. A pesar de las diferencias de género y etapas reproductivas, los murciélagos mostraron el mismo comportamiento en tres períodos de radiotelemetría y en más de 500 días de seguimiento de murciélagos: cada uno utilizó perchas separadas, cambiaban de percha poco frecuentemente, y se asociaron con otros murciélagos sólo en las perchas comunales. Esta red fue semejante a una red sin escala en la que la distribución del número de eslabones de cada percha cumplió una ley potencial. A pesar de estar dispersas en un área geográfica extensa (>200 km2), cada percha estaba conectada con otras por menos de tres eslabones. Una percha (el centro o percha comunal) definió la arquitectura de la red porque tenía a la mayoría de los eslabones. El hecho de que la red mostrara propiedades libres de escala tiene implicaciones profundas para la gestión de árboles que funcionan como perchas. Las redes libres de escala proporcionan alta tolerancia a eventos estocásticos como la remoción aleatoria de perchas, pero son susceptibles a la remoción selectiva de nodos centrales. El análisis de redes es una herramienta útil para el entendimiento de la organización estructural del uso de de árboles y permite el juicio informado de la importancia relativa de árboles individuales y por lo tanto la derivación de decisiones administrativas apropiadas Los planificadores y gestores de la conservación deberían enfatizar la importancia diferencial de árboles y considerarlos análogos a los centros de servicio vitales en las sociedades humanas. [source] Kinetic analysis of hyaluronidase activity using a bioactive MRI contrast agentCONTRAST MEDIA & MOLECULAR IMAGING, Issue 3 2006Liora Shiftan Abstract One of the attractions of molecular imaging using ,smart' bioactive contrast agents is the ability to provide non-invasive data on the spatial and temporal changes in the distribution and expression patterns of specific enzymes. The tools developed for that aim could potentially also be developed for functional imaging of enzyme activity itself, through quantitative analysis of the rapid dynamics of enzymatic conversion of these contrast agents. High molecular weight hyaluronan, the natural substrate of hyaluronidase, is a major antiangiogenic constituent of the extracellular matrix. Degradation by hyaluronidase yields low molecular weight fragments, which are proangiogenic. A novel contrast material, HA-GdDTPA-beads, was designed to provide a substrate analog of hyaluronidase in which relaxivity changes are induced by enzymatic degradation. We show here a first-order kinetic analysis of the time-dependent increase in R2 as a result of hyaluronidase activity. The changes in R2 and the measured relaxivity of intact HA-GdDTPA-beads (r2B) and HA-GdDTPA fragments (r2D) were utilized for derivation of the temporal drop in concentration of GdDTPA in HA-GdDTPA-beads as the consequence of the release of HA-GdDTPA fragments. The rate of dissociation of HA-GdDTPA from the beads showed typical bell-shaped temperature dependence between 7 and 36 °C with peak activity at 25 °C. The tools developed here for quantitative dynamic analysis of hyaluronidase activity by MRI would allow the use of activation of HA-GdDTPA-beads for the determination of the role of hyaluronidase in altering the angiogenic microenvironment of tumor micro metastases. Copyright © 2006 John Wiley & Sons, Ltd. [source] Dispersion of Dust Acoustic Modes and Perturbations of Plasma Flux BalanceCONTRIBUTIONS TO PLASMA PHYSICS, Issue 3 2007V. Tsytovich Abstract Previous considerations of dust acoustic waves is demonstrated to be inconsistent - the required equilibrium state for perturbations was not defined since balance of plasma fluxes was neglecting. The self-consistent treatment shows that plasma flux perturbations are accompanying any collective waves propagating in dusty plasmas and can play an important role in wave dispersion, wave damping and can create instabilities. This is illustrated by the derivation of dispersion relation for dust acoustic modes taking into account the plasma flux balances and plasma flux perturbations by waves. The result of this approach shows that the dust acoustic waves with linear dependence of wave frequency on the wave number exist only in restricted range of the wave numbers. Only for wave numbers larger than some critical wave number for low frequency modes the frequency can be have approximately a linear dependence on wave number and can be called as dust acoustic wave but the phase velocity of these waves is different from that which can be obtained neglecting the flux balance and depends on grain charge variations which are determined by the balance of fluxes. The presence of plasma fluxes previously neglected is the main typical feature of dusty plasmas. The dispersion relation in the range of small wave numbers is found to be mainly determined by the change of the plasma fluxes and is quite different from that of dust acoustic type, namely it is found to have the same form as the well known dispersion relation for the gravitational instability. This result proves in general way the existence of the collective grain attractions of negatively charged grains for for large distances between them and for any source of ionization. The attraction of grains found from dispersion relation of the dust acoustic branch coincides with that found previously for pair grain interactions using some models for the ionization source. For the existing experiments the effective Jeans length for such attraction is estimated to be about 8 , 10 times larger than the ion Debye length and the effective gravitational constant for the grain attraction is estimated to be several orders of magnitude larger than the usual gravitational constant. The grain attraction at large inter-grain distances described by the gravitationlike grain instability is considered as the simplest explanation for observed dust cloud clustering, formation of dust structures including the plasma crystals. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Developmental psychopathology in adolescence: findings from a Swiss study , the NAPE Lecture 2005ACTA PSYCHIATRICA SCANDINAVICA, Issue 1 2006H.-C. Steinhausen Objective:, Presentations of selective findings coming from the Zurich Adolescent Psychology and Psychopathology Study with two major aims: i) the study of the prevalence, course, and correlates of mental disorders in adolescence, and ii) the study of the determinants and processes of mental disorders in adolescence. Method:, A representative sample of n = 1964 children and adolescents was studied in the canton of Zurich in 1994. Additional waves of data collection took place in 1997 and 2000/2001. Mean ages at these three assessments were 13, 16, and 20 years. Each wave contained a two-stage procedure of assessment with screening by questionnaires and consecutive interviewing. The main constructs used were general and specific measures of psychopathology, life events, coping styles, self-related cognitions, and quality of the social network. Results:, Prevalence rates of any mental disorder in school-age at the time of assessment was 22.5% fitting into a transcultural range of 18,26% based on DSM-III-R criteria. Furthermore, the derivation and validation of a four-group adolescent drinker typology was demonstrated. Additionally, the prevalence and continuity of functional-somatic symptoms from adolescence to young adulthood was shown. Another piece of the research tested for the identification of risk, compensatory, vulnerability, and protective factors influencing behaviour problems and found remarkably different frequencies across the four types of moderating factors. Conclusion:, The presented findings provide further understanding of the developmental psychology and psychopathology of adolescence and the service, intervention, and prevention needs of this age-group. [source] Can We Derive the Principle of Compositionality (if We Deflate Understanding)?DIALECTICA, Issue 2 2009Antonio Rauti Paul Horwich has claimed that we can derive a certain form of the principle of compositionality from a deflationary account of what it is to understand a complex expression. If this were the case, we would realize a surprising theoretical economy, and if the derivation involved basic ideas from a use theory of meaning, we would have a novel argument for use theories of meaning. Horwich does not offer a detailed derivation. In this paper I reconstruct a possible derivation and show that it begs the question. I then extend my discussion to explain why it is unlikely that alternative arguments can fare better. [source] Comparison of anti-inflammatory activities of ruscogenin, a major steroidal sapogenin from Radix Ophiopogon japonicus, and Its succinylated derivative, RUS-2HSDRUG DEVELOPMENT RESEARCH, Issue 4 2008Ya-Lin Huang Abstract Ruscogenin (RUS), first isolated from Ruscus aculeatus, is also a major steroidal sapogenin of the traditional Chinese herb Radix Ophiopogon japonicus. It has robust anti-inflammatory activities. In previous studies, a ruscogenin affinity column, derived from succinylated ruscogenin (RUS-2HS), was used to purify an antibody of ruscogenin. A ruscogenin affinity column can also be used to explore its protein targets. However, until now there have been no related pharmacological reports about ruscogenin derivatives. Whether the activity groups of ruscogenin have been blocked during the derivation process remains unknown. The present study was performed to compare the anti-inflammatory activities in vitro of RUS-2HS and ruscogenin. Both compounds reduced tumor necrosis factor-, (TNF-,)-induced adhesion of human pro-myelocytic leukemia cells (HL-60) to endothelial ECV304 cells with IC50 values of 6.90,nM and 7.45,nM, respectively. They were also inhibited overexpression of ICAM-1 in ECV304 cells at the mRNA level as evaluated by real-time PCR and at the protein level evaluated by flow cytometry with similar potency. Such data demonstrate that the functional groups of ruscogenin were not blocked by derivation, suggesting further use of the ruscogenin affinity column for target investigation. Meanwhile, RUS-2HS was found to have remarkable anti-inflammatory activity for the first time, indicating it would be a new lead compound with improved bioavailability. Drug Dev Res 69: 196,202, 2008. © 2008 Wiley-Liss, Inc. [source] A catchment scale evaluation of the SIBERIA and CAESAR landscape evolution modelsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2010GR Hancock Abstract Landscape evolution models provide a way to determine erosion rates and landscape stability over times scales from tens to thousands of years. The SIBERIA and CAESAR landscape evolution models both have the capability to simulate catchment,wide erosion and deposition over these time scales. They are both cellular, operate over a digital elevation model of the landscape, and represent fluvial and slope processes. However, they were initially developed to solve research questions at different time and space scales and subsequently the perspective, detail and process representation vary considerably between the models. Notably, CAESAR simulates individual events with a greater emphasis on fluvial processes whereas SIBERIA averages erosion rates across annual time scales. This paper describes how both models are applied to Tin Camp Creek, Northern Territory, Australia, where soil erosion rates have been closely monitored over the last 10 years. Results simulating 10,000 years of erosion are similar, yet also pick up subtle differences that indicate the relative strengths and weaknesses of the two models. The results from both the SIBERIA and CAESAR models compare well with independent field data determined for the site over different time scales. Representative hillslope cross-sections are very similar between the models. Geomorphologically there was little difference between the modelled catchments after 1000 years but significant differences were revealed at longer simulation times. Importantly, both models show that they are sensitive to input parameters and that hydrology and erosion parameter derivation has long-term implications for sediment transport prediction. Therefore selection of input parameters is critical. This study also provides a good example of how different models may be better suited to different applications or research questions. Copyright © 2010 John Wiley & Sons, Ltd and Commonwealth of Australia [source] High resolution quantification of gully erosion in upland peatlands at the landscape scaleEARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2010Martin Evans Abstract The upland peatlands of the UK are severely eroded, with large areas affected by gully erosion. The peatlands are important areas of carbon storage and provide a range of other ecosystem services including water supply and biodiversity all of which are negatively impacted by erosion of the upland surface. The magnitude of the gully erosion, and consequent adjustment of the peatland morphology, is such that in degraded peatlands the extent and magnitude of erosion is a major control on peatland function. Accurate mapping of gully form is therefore a necessary precondition to the understanding and management of these systems. This paper develops an approach to extracting gully maps from high resolution digital elevation models (DEMs). Gully maps of the Bleaklow Plateau in northern England were derived from a 2,m LiDAR DEM by combining areas of low difference from mean elevation and high positive plan curvature. Gully depth was modelled by interpolating between gully edges. Testing of the gully mapping and depth modelling against aerial photography, manual interpretation of the DEM and ground survey revealed that gully plan form is well represented and gully width and depth are modelled with tolerances close to the horizontal and vertical resolution of the LiDAR imagery. Estimates of gully width and depth were less reliable for gullies with total width of less than four pixels. The approach allows for the first time the derivation of accurate estimates of gully extent and magnitude over large areas and provides the basis for modelling a range of processes controlled by gullying. The approach has wider applicability to mapping gully erosion in a wide range of environments. Copyright © 2010 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||