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Averaging
Kinds of Averaging Terms modified by Averaging Selected AbstractsTROSY effects in MAS solid-state NMRCONCEPTS IN MAGNETIC RESONANCE, Issue 2 2008Veniamin Chevelkov Abstract Use of transverse relaxation-optimized spectroscopy (TROSY) type techniques had a dramatic impact on the study of large proteins with a molecular weight >30kDa for solution-state NMR. In the solid-state, such an effect would not be expected a prior, as the investigated molecules are immobilized. However, local motions induce fluctuations of the local fields experienced by the nuclear spins and, this way, are effective for relaxation. We demonstrate that protein dynamics can significantly influence the resonance line width in ultra high resolution MAS (magic angle spinning) solid-state NMR experiments. Averaging of the 15NH,/, multiplet components as a consequence of 1H decoupling induces effective broadening of the 15N resonance. Application of TROSY type techniques that select only the narrow component of the multiplet pattern results in an increased resolution and, thus, will be of benefit for MAS solid-state NMR spectroscopy. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part A 32A: 143,156, 2008. [source] 2001 August earthquake swarm at Shadwan Island, Gulf of Suez, EgyptGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2006Ahmed Badawy SUMMARY The earthquake swarm that struck Shadwan Island at the entrance of the Gulf of Suez in 2001 August included 408 events. Almost all of these events (94 per cent) were microearthquakes and only 6 per cent had small measurable magnitudes (5.0 > ML, 3.0). Most of the earthquakes were weak and followed each other so closely in time that they could not be identified at more distant stations. The fault plane solutions of the strongest events of the swarm show almost identical focal mechanisms, predominately normal faulting with a significant sinistral strike-slip component for nodal planes trending NW,SE. A comparison with the mechanisms of the 1969 and 1972 events which took place 20 km north of the swarm epicentral region shows similarities in faulting type and orientation of nodal planes. The azimuths of T -axes determined from focal mechanisms in this study are oriented in the NNE,SSW direction. This direction is consistent with the present-day stress field derived from borehole breakouts in the southern Gulf of Suez and the last phase of stress field changes in the Late Pleistocene, as well as with recent GPS results. The source parameters of the largest (ML, 3.0) events of the 2001 August Shadwan swarm have been estimated from the P -wave spectra of the Egyptian National Seismograph Network (ENSN). Averaging of the values obtained at different stations shows relatively similar source parameters, including a fault length of 0.65 ,L, 2 km, a seismic moment of 7.1 × 1012,Mo, 3.0 × 1014 N m and a stress drop of 0.4 ,,,, 10 bar. [source] Handling linguistic web information based on a multi-agent systemINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 5 2007Zheng Pei Much information over the Internet is expressed by natural languages. The management of linguistic information involves an operation of comparison and aggregation. Based on the Ordered Weighted Averaging (OWA) operator and modifying indexes of linguistic terms (their indexes are fuzzy numbers on [0,T] , R+), new linguistic aggregating methods are presented and their properties are discussed. Also, based on a multi-agent system and new linguistic aggregating methods, gathering linguistic information over the Internet is discussed. Moreover, by fixing the threshold ,, "soft filtering information" is proposed and better Web pages (or documents) that the user needs are obtained. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 435,453, 2007. [source] Model uncertainty in cross-country growth regressionsJOURNAL OF APPLIED ECONOMETRICS, Issue 5 2001Carmen Fernández We investigate the issue of model uncertainty in cross-country growth regressions using Bayesian Model Averaging (BMA). We find that the posterior probability is spread widely among many models, suggesting the superiority of BMA over choosing any single model. Out-of-sample predictive results support this claim. In contrast to Levine and Renelt (1992), our results broadly support the more ,optimistic' conclusion of Sala-i-Martin (1997b), namely that some variables are important regressors for explaining cross-country growth patterns. However, care should be taken in the methodology employed. The approach proposed here is firmly grounded in statistical theory and immediately leads to posterior and predictive inference. Copyright © 2001 John Wiley & Sons, Ltd. [source] Returns to Schooling and Bayesian Model Averaging: A Union of Two LiteraturesJOURNAL OF ECONOMIC SURVEYS, Issue 2 2004Justin L. Tobias Abstract., In this paper, we review and unite the literatures on returns to schooling and Bayesian model averaging. We observe that most studies seeking to estimate the returns to education have done so using particular (and often different across researchers) model specifications. Given this, we review Bayesian methods which formally account for uncertainty in the specification of the model itself, and apply these techniques to estimate the economic return to a college education. The approach described in this paper enables us to determine those model specifications which are most favored by the given data, and also enables us to use the predictions obtained from all of the competing regression models to estimate the returns to schooling. The reported precision of such estimates also account for the uncertainty inherent in the model specification. Using U.S. data from the National Longitudinal Survey of Youth (NLSY), we also revisit several ,stylized facts' in the returns to education literature and examine if they continue to hold after formally accounting for model uncertainty. [source] A solid-state NMR study of phase structure, molecular interactions, and mobility in blends of citric acid and paracetamolJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2009S. Schantz Abstract Citric acid anhydrate (CAA) and paracetamol (PARA), prepared as crystalline physical mixtures and as amorphous blends, were studied using 13C solid-state cross polarization magic angle spinning (CPMAS) NMR. Amorphous blends showed significant line broadening from the conformational distribution as compared to the crystalline samples. Also, chemical shift variations were observed between crystalline and amorphous blends, which were attributed to differences in intermolecular interactions. Averaging of proton rotating-frame spin-lattice relaxation times (T1,) probed via different 13C sites in the amorphous blends confirmed molecular level mixing. For some, initially amorphous, sample compositions the onset of crystallization was evident directly from spectra and from the significantly longer T1, relaxations. Thus, crystallization caused phase separation with properties of the two phases resembling those of pure CAA and PARA, respectively. 13C spectra of amorphous 50/50 (w/w, %) CAA/PARA recorded from above the glass transition temperature broadened as the temperature increased to a maximum at T,,,Tg,+,33 K. This was the result of a dynamic interference between the line narrowing techniques being applied and the time scale of molecular reorientation in the miscible melt. The derived average correlation time was found to correspond well with previous results from melt rheology. We conclude that the underlying reasons for physical instability (i.e., crystallization from the miscible melt, including molecular interactions and dynamics) of this class of amorphous binary mixtures can be effectively evaluated using NMR spectroscopy. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1862,1870, 2009 [source] Pluralism and diversity: trends in the use and application of ordination methods 1990-2007JOURNAL OF VEGETATION SCIENCE, Issue 4 2009Henrik Von Wehrden Abstract Question: What are the trends and patterns in the application of ordination techniques in vegetation science since 1990? Location: Worldwide literature analysis. Methods: Evaluation of five major journals of vegetation science; search of all ISI-listed ecological journals. Data were analysed with ANCOVAs, Spearman rank correlations, GLMs, biodiversity indices and simple graphs. Results: The ISI search retrieved fewer papers that used ordinations than the manual evaluation of five selected journals. Both retrieval methods revealed a clear trend in increasing frequency of ordination applications from 1990 to the present. Canonical Correspondence Analysis was far more frequently detected by the ISI search than any other method. Applications such as Correspondence Analysis/Reciprocal Averaging and Detrended Correspondence Analysis have increasingly been used in studies published in "applied" journals, while Canonical Correspondence Analysis, Redundancy Analysis and Non-Metric Multidimensional Scaling were more frequently used in journals focusing on more "basic" research. Overall, Detrended Correspondence Analysis was the most commonly applied method within the five major journals, although the number of publications slightly decreased over time. Use of Non-Metric Multidimensional Scaling has increased over the last 10 years. Conclusion: The availability of suitable software packages has facilitated the application of certain techniques such as Non-Metric Multidimensional Scaling. However, choices of ordination techniques are currently less driven by the constraints imposed by the software; there is also limited evidence that the choice of methods follows social considerations such as the need to use fashionable methods. Methodological diversity has been maintained or has even increased over time and reflects the researcher's need for diverse analytical tools suitable to address a wide range of questions. [source] Lower fitness of hatchery and hybrid rainbow trout compared to naturalized populations in Lake Superior tributariesMOLECULAR ECOLOGY, Issue 11 2004L. M. MILLER Abstract We have documented an early life survival advantage by naturalized populations of anadromous rainbow trout Oncorhynchus mykiss over a more recently introduced hatchery population and outbreeding depression resulting from interbreeding between the two strains. We tested the hypothesis that offspring of naturalized and hatchery trout, and reciprocal hybrid crosses, survive equally from fry to age 1+ in isolated reaches of Lake Superior tributary streams in Minnesota. Over the first summer, offspring of naturalized females had significantly greater survival than offspring of hatchery females in three of four comparisons (two streams and 2 years of stocking). Having an entire naturalized genome, not just a naturalized mother, was important for survival over the first winter. Naturalized offspring outperformed all others in survival to age 1+ and hybrids had reduced, but intermediate, survival relative to the two pure crosses. Averaging over years and streams, survival relative to naturalized offspring was 0.59 for hybrids with naturalized females, 0.37 for the reciprocal hybrids, and 0.21 for hatchery offspring. Our results indicate that naturalized rainbow trout are better adapted to the conditions of Minnesota's tributaries to Lake Superior so that they outperform the hatchery-propagated strain in the same manner that many native populations of salmonids outperform hatchery or transplanted fish. Continued stocking of the hatchery fish may conflict with a management goal of sustaining the naturalized populations. [source] Continuous arterial spin labeling at the human common carotid artery: the influence of transit timesNMR IN BIOMEDICINE, Issue 1 2005Toralf Mildner Abstract In evaluating the sensitivity of arterial spin labeling (CASL) and for quantification of perfusion, knowledge of the transit time from the labeling plane to the imaging slice is crucial. The purpose of the current study was to obtain estimates of transit times relevant under the specific experimental conditions of CASL in human subjects using a separate local labeling coil at the neck. Specifically, the post-label delay (PLD), i.e. the time between the end of the labeling period and the image acquisition, was varied either with or without additional application of crusher gradients to suppress intravascular signal contributions. The overall sensitivity change for varying the PLD between 1000 and 1700,ms was low. A tissue transit time from the neck to an axial supraventricular section through Broca's knee was obtained by fitting the PLD dependence to a two-compartment model. Averaging over subjects yielded 1930,±,110,ms for the tissue transit time, and 73,±,5,ml,min,1 100,g,1 for the cerebral blood flow. Small areas that exhibited a very high signal change upon labeling were indicative of regional variation in cerebral blood flow related to vascular anatomy. Copyright © 2004 John Wiley & Sons, Ltd. [source] Reverse Electrical Remodeling of the Atria Post Cardioversion in Patients Who Remain in Sinus Rhythm Assessed by Signal Averaging of the P-WavePACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2007NAGIB CHALFOUN M.D. Objectives: This study was designed to determine whether the signal-averaged electrocardiogram of the P-wave (SAPW) is an independent predictor of recurrence of atrial fibrillation (AF) post cardioversion (CV), and to assess atrial remodeling using SAPW. Background: There are limited electrophysiologic data to predict the recurrence of AF post-CV. The electrical remodeling that occurs post-CV is poorly understood. Methods: Sixty-four patients with persistent AF undergoing CV were prospectively enrolled. SAPW parameters were measured the day of CV and repeated at 1 month. These SAPW parameters were compared to other baseline indices for the recurrence of AF. Results: Sixty patients (94%) had successful CV. At 1 month, 22 (37%) maintained sinus rhythm (SR). The SAPW total duration decreased significantly in those who remained in SR (159 ms ± 19 to 146 ms ± 17; P < 0.0001). Only the duration of AF (46 ± 50 days vs 147 ± 227 days, P = 0.03) and the presence of left ventricular hypertrophy (LVH, 12% vs 65%, P = 0.0006) were significantly associated with recurrence of AF. Atrial size strongly correlated with the SAPW duration in patients who remained in SR (R2= 0.67, P = 0.003) but not in those who returned to AF (R2= 0.11, P = 0.65). Conclusions: Atrial electrical reverse remodeling occurs in patients with AF who maintain SR post-CV. This remodeling is likely inversely related to the duration of AF and LVH. SAPW duration does not predict recurrence of AF post-CV. [source] Presidential Address: The Cost of Active InvestingTHE JOURNAL OF FINANCE, Issue 4 2008KENNETH R. FRENCH ABSTRACT I compare the fees, expenses, and trading costs society pays to invest in the U.S. stock market with an estimate of what would be paid if everyone invested passively. Averaging over 1980,2006, I find investors spend 0.67% of the aggregate value of the market each year searching for superior returns. Society's capitalized cost of price discovery is at least 10% of the current market cap. Under reasonable assumptions, the typical investor would increase his average annual return by 67 basis points over the 1980,2006 period if he switched to a passive market portfolio. [source] Model Selection and Model Averaging by CLAESKENS, G. and HJORT, N. L.BIOMETRICS, Issue 2 2009Thomas M. Loughin No abstract is available for this article. [source] A Pragmatic Recipe for the Treatment of Hindered Rotations in the Vibrational Averaging of Molecular PropertiesCHEMPHYSCHEM, Issue 1 2008Brendan C. Mort Dr. Abstract A computational protocol for the treatment of hindered rotations in the vibrational averaging of molecular properties is described. As examples, the specific rotations of (R) -methyloxirane, (1S) -methylnorbornanone, and (S) -epichlorohydrin and the spin-spin coupling constant for are investigated. For each of the four molecules, the relaxed and unrelaxed potential energy surfaces along the rotational coordinate of interest are used to solve the nuclear Schrödinger equation using a pseudospectral method. Analysis of the results demonstrate that the vibrational averaging for low-frequency modes that represent hindered rotations can lead to unphysical behavior at high temperatures while simply neglecting the rotational contributions is also not desirable. The method described in this work connects the (an)harmonic oscillator behavior at low temperatures with the free rotor-like behavior at high temperatures. [source] BetweenIT: An Interactive Tool for Tight InbetweeningCOMPUTER GRAPHICS FORUM, Issue 2 2010Brian Whited Abstract The generation of inbetween frames that interpolate a given set of key frames is a major component in the production of a 2D feature animation. Our objective is to considerably reduce the cost of the inbetweening phase by offering an intuitive and effective interactive environment that automates inbetweening when possible while allowing the artist to guide, complement, or override the results. Tight inbetweens, which interpolate similar key frames, are particularly time-consuming and tedious to draw. Therefore, we focus on automating these high-precision and expensive portions of the process. We have designed a set of user-guided semi-automatic techniques that fit well with current practice and minimize the number of required artist-gestures. We present a novel technique for stroke interpolation from only two keys which combines a stroke motion constructed from logarithmic spiral vertex trajectories with a stroke deformation based on curvature averaging and twisting warps. We discuss our system in the context of a feature animation production environment and evaluate our approach with real production data. [source] Calculation of Posterior Probabilities for Bayesian Model Class Assessment and Averaging from Posterior Samples Based on Dynamic System DataCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2010Sai Hung Cheung Because of modeling uncertainty, a set of competing candidate model classes may be available to represent a system and it is then desirable to assess the plausibility of each model class based on system data. Bayesian model class assessment may then be used, which is based on the posterior probability of the different candidates for representing the system. If more than one model class has significant posterior probability, then Bayesian model class averaging provides a coherent mechanism to incorporate all of these model classes in making probabilistic predictions for the system response. This Bayesian model assessment and averaging requires calculation of the evidence for each model class based on the system data, which requires the evaluation of a multi-dimensional integral involving the product of the likelihood and prior defined by the model class. In this article, a general method for calculating the evidence is proposed based on using posterior samples from any Markov Chain Monte Carlo algorithm. The effectiveness of the proposed method is illustrated by Bayesian model updating and assessment using simulated earthquake data from a ten-story nonclassically damped building responding linearly and a four-story building responding inelastically. [source] Magnetic susceptibility: Further insights into macroscopic and microscopic fields and the sphere of LorentzCONCEPTS IN MAGNETIC RESONANCE, Issue 1 2003C.J. Durrant Abstract To make certain quantitative interpretations of spectra from NMR experiments carried out on heterogeneous samples, such as cells and tissues, we must be able to estimate the magnetic and electric fields experienced by the resonant nuclei of atoms in the sample. Here, we analyze the relationships between these fields and the fields obtained by solving the Maxwell equations that describe the bulk properties of the materials present. This analysis separates the contribution to these fields of the molecule in which the atom in question is bonded, the "host" fields, from the contribution of all the other molecules in the system, the "external" fields. We discuss the circumstances under which the latter can be found by determining the macroscopic fields in the sample and then removing the averaged contribution of the host molecule. We demonstrate that the results produced by the, so-called, "sphere of Lorentz" construction are of general validity in both static and time-varying cases. This analytic construct, however, is not "mystical" and its justification rests not on any sphericity in the system but on the local uniformity and isotropy, i.e., spherical symmetry, of the medium when averaged over random microscopic configurations. This local averaging is precisely that which defines the equations that describe the macroscopic fields. Hence, the external microscopic fields, in a suitably averaged sense, can be estimated from the macroscopic fields. We then discuss the calculation of the external fields and that of the resonant nucleus in NMR experiments. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part A 18A: 72,95, 2003 [source] Signal de-noising in magnetic resonance spectroscopy using wavelet transformsCONCEPTS IN MAGNETIC RESONANCE, Issue 6 2002Hector F. Cancino-De-Greiff Abstract Computer signal processing is used for quantitative data analysis (QDA) in magnetic resonance spectroscopy (MRS). The main difficulty in QDA is that MRS signals appear to be contaminated with random noise. Noise reduction can be achieved by coherent averaging, but it is not always possible to average many MRS waveforms. Wavelet shrinkage de-noising (WSD) is a technique that can be employed in this case. The potentialities of WSD in MRS, alone and combined with the Cadzow algorithm, are analyzed through computer simulations. The results can facilitate an appropriate application of WSD, as well as a deeper understanding of this technique. © 2002 Wiley Periodicals, Inc. Concepts Magn Reson 14: 388,401, 2002 [source] Motional smearing of electrically recovered couplings measured from multipulse transientsCONCEPTS IN MAGNETIC RESONANCE, Issue 3 2001Scott A. Riley Abstract The measurement of residual dipolar and quadrupolar coupling constants in the liquid phase by using an electric field to destroy the isotropic nature of molecular tumbling is complicated by charge-induced turbulent motion. In many cases this motion is due to charge injection at electrode surfaces, an effect that leads to an apparent removal of electrically recovered anisotropic spectral splittings when measured from a spin-echo envelope modulation produced by a train of radio frequency (rf) pulses. To understand this averaging, the effect of quadrupolar couplings and enhanced molecular diffusion on free-induction, spin-echo, and Carr,Purcell signals is analytically determined in the special case of homogeneous rf pulses. Additional signal damping due to rf inhomogeneity and coupling constant heterogeneity is determined by numerically extending the kernel formalism introduced by Herzog and Hahn to understand spin diffusion in solids. Finally, the merit of the numerical approach is tested by comparison with analytical results for homogeneous rf pulses and experimental results for perdeuterated nitrobenzene involving inhomogeneous rf pulses and coupling heterogeneity. © 2001 John Wiley & Sons, Inc. Concepts Magn Reson 13: 171,189, 2001 [source] Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized TorusCONTRIBUTIONS TO PLASMA PHYSICS, Issue 4 2004F. Greiner Abstract The spatio-temporal dynamics of large-scale structures in curved magnetic field of simple magnetized torus (SMT) are presented. The experiments are performed in the SMT BLAAMANN and employ the techniques of conditional averaging (CA) and cross-correlation (CCF) of Langmuir probe data. By means of a detailed comparison of radio-frequency and thermionic discharges, it is shown that general features of the observed large-scale structures are independent of the discharge mechanism. Further, the observed large scale structures have a pronounced spatio-temporal periodicity, which suggests a description as mode-like. The conjectured relationship between the observed coherent structures and the inverse energy cascade is therefore questioned again. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Doppler spectral line shapes in low frequency turbulent plasmasCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2004Y. Marandet Abstract In this paper we investigate the influence of low frequency, i.e. drift wave like turbulence on the spectral line shapes in magnetized plasmas. The measured spectrum, which is obtained through both spatial and time averaging processes, is shown to contain information on turbulence. Using a statistical description of the turbulent fluctuations, we investigate the effects of density, fluid velocity and temperature fluctuations on the Doppler profile of a spectral line. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spatial correlations of Diceroprocta apache and its host plants: evidence for a negative impact from Tamarix invasionECOLOGICAL ENTOMOLOGY, Issue 1 2002Aaron R. Ellingson Abstract 1. The hypothesis that the habitat-scale spatial distribution of the Apache cicada Diceroprocta apache Davis is unaffected by the presence of the invasive exotic saltcedar Tamarix ramosissima was tested using data from 205 1-m2 quadrats placed within the flood-plain of the Bill Williams River, Arizona, U.S.A. Spatial dependencies within and between cicada density and habitat variables were estimated using Moran's I and its bivariate analogue to discern patterns and associations at spatial scales from 1 to 30 m. 2. Apache cicadas were spatially aggregated in high-density clusters averaging 3 m in diameter. A positive association between cicada density, estimated by exuvial density, and the per cent canopy cover of a native tree, Goodding's willow Salix gooddingii, was detected in a non-spatial correlation analysis. No non-spatial association between cicada density and saltcedar canopy cover was detected. 3. Tests for spatial cross-correlation using the bivariate IYZ indicated the presence of a broad-scale negative association between cicada density and saltcedar canopy cover. This result suggests that large continuous stands of saltcedar are associated with reduced cicada density. In contrast, positive associations detected at spatial scales larger than individual quadrats suggested a spill-over of high cicada density from areas featuring Goodding's willow canopy into surrounding saltcedar monoculture. 4. Taken together and considered in light of the Apache cicada's polyphagous habits, the observed spatial patterns suggest that broad-scale factors such as canopy heterogeneity affect cicada habitat use more than host plant selection. This has implications for management of lower Colorado River riparian woodlands to promote cicada presence and density through maintenance or creation of stands of native trees as well as manipulation of the characteristically dense and homogeneous saltcedar canopies. [source] Magnitude and variability of process rates in fungal diversity-litter decomposition relationshipsECOLOGY LETTERS, Issue 11 2005Christian K. Dang Abstract There is compelling evidence that losses in plant diversity can alter ecosystem functioning, particularly by reducing primary production. However, impacts of biodiversity loss on decomposition, the complementary process in the carbon cycle, are highly uncertain. By manipulating fungal decomposer diversity in stream microcosm experiments we found that rates of litter decomposition and associated fungal spore production are unaffected by changes in decomposer diversity under benign and harsher environmental conditions. This result calls for caution when generalizing outcomes of biodiversity experiments across systems. In contrast to their magnitude, the variability of process rates among communities increased when species numbers were reduced. This was most likely caused by a portfolio effect (i.e. statistical averaging), with the uneven species distribution typical of natural communities tending to weaken that effect. Curbing species extinctions to maintain ecosystem functioning thus can be important even in situations where process rates are unaffected. [source] Optimal separation times for electrical field flow fractionation with Couette flowsELECTROPHORESIS, Issue 20 2008Jennifer Pascal Abstract The prediction of optimal times of separation as a function of the applied electrical field and cation valence have been studied for the case of field flow fractionation [Martin M., Giddings J. C., J. Phys. Chem. 1981, 85, 727] with charged solutes. These predictions can be very useful to a priori design or identify optimal operating conditions for a Couette-based device for field flow fractionation when the orthogonal field is an electrical field. Mathematically friendly relationships are obtained by applying the method of spatial averaging to the solute species continuity equation; this is accomplished after the role of the capillary geometrical dimensions on the applied electrical field equations has been assessed [Oyanader M. A., Arce P., Electrophoresis 2005; 26, 2857]. Moreover, explicit analytical expressions are derived for the effective parameters, i.e. diffusivity and convective velocity as functions of the applied (orthogonal) electrical field. These effective transport parameters are used to study the effect of the cation valence of the solutes and of the magnitude of the applied orthogonal electrical field on the values of the optimal time of separation. These parameters play a significant role in controlling the optimal separation time, leading to a family of minimum values, for particular magnitudes of the applied orthogonal electrical field. [source] Role of geometrical dimensions in electrophoresis applications with orthogonal fieldsELECTROPHORESIS, Issue 15 2005Mario A. Oyanader Abstract The role of geometrical dimensions in electrophoresis applications with axial and orthogonal (secondary) electric fields is investigated using a rectangular capillary channel. In particular, the role of the applied orthogonal electrical field in controlling key parameters involved in the effective diffusivity and effective (axial) velocity of the solute is identified. Such mathematically friendly relationships are obtained by applying the method of spatial averaging to the solute species continuity equation; this is accomplished after the role of the capillary geometrical dimensions on the applied electrical field equations has been studied. Moreover, explicit analytical expressions are derived for the effective parameters, i.e., diffusivity and convective velocity as functions of the applied (orthogonal) electric field. Previous attempts (see Sauer et al., 1995) have only led to equations for these parameters that require numerical solution and, therefore, limited the use of such results to practical applications. These may include, for example, the design of separation processes as well as environmental applications such as soil reclamation and wastewater treatment. An illustration of how a secondary electrical field can aid in reducing the optimal separation time is included. [source] Opportunism of Conidiobolus obscurus stems from depression of infection in situ to progeny colonies of host alatae as disseminators of the aphid-pathogenic fungusENVIRONMENTAL MICROBIOLOGY, Issue 4 2007Guo-Zhong Zhang Summary Conidiobolus (Entomophthorales: Ancylistaceae) includes common aphid pathogens but causes sporadic mycosis worldwide. This epizootiological opportunism was explored herein by examining the potential of mycosis transmission in the progeny colonies of 513 Myzus persicae alates as disseminators of C. obscurus often infecting aphids. The alates exposed to spore showers were flown for 2.05 (0.01,8.95) km on flight mills and then reared individually on cabbage at 20,23°C for 14 day colonization. All truly infected alates were mycosed within 6 days and averagely left 3.9 (0,15) nymphs while those uninfected produced 11.6 (0,35) nymphs during the same period. Secondary and tertiary infections occurred only in 16.2% and 4.8% of the progeny colonies of the mycosed alates respectively, due to c. 60% of the cadavers forming resting spores. Most of the contagious infections appeared on days 4,8 after colonization and no more occurred from day 11 onwards. Trends of colony sizes (last-day averaging 51.5 aphids) and mycosis transmission (sixth-day maximum 6.3%) fit well to logistic (r 2 = 0.99) and Gompertz growth models (r 2 = 0.91) respectively. The results confirm that the opportunism of C. obscurus stems from depression of contagious infection after dissemination by host alates and suggest that it be overwhelmed by the prevalence of other non-resting fungal species. [source] Long-term trends in liver neoplasms in brown bullhead in the Buffalo River, New York, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Darrel J. Lauren Abstract The Buffalo River area of concern (AOC) was assigned an impaired status for the fish tumors and other deformities beneficial use impairment category by the New York State Department of Environmental Protection in 1989. This was initially based on an inadequately documented brown bullhead (Ameiurus nebulosus) feeding study using river sediment extracts. The presence of liver tumors was subsequently supported by reports of a 19 to 27% prevalence in wild brown bullhead between 1983 and 1988 and a 4.8% prevalence in 1998. However, neither fish size (or age) nor sample locations were given, and histopathological definitions were inconsistent in these previous studies. Therefore, in 2008, we re-evaluated the prevalence of hepatocellular and chloangiocellular tumors (as well as other gross indicators of fish health) in brown bullhead averaging 25,cm in length collected from three reaches of the Buffalo River and recorded our collection sites by global positioning system. Among the 37 fish of appropriate size collected, only three exhibited liver tumors (8%). The tumors were evenly distributed within the three reaches, and only hepatocellular tumors were found. There were no differences in the prevalence of hepatic foci of alteration, body weight, length, or hepatosomatic index among the three reaches, but the conditions factor was significantly lower in fish from reach 2. Natural attenuation of water and sediment quality are the most likely causes for the decrease in liver tumors. The prevalence of liver tumors between 1998 and 2008 in the Buffalo River is similar to that found in recovery-stage AOCs and some Great Lakes reference areas. Environ. Toxicol. Chem. 2010; 29:1748,1754. © 2010 SETAC [source] Multiple computer-automated structure evaluation study of aquatic toxicity.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2003Abstract An acute toxicity model was constructed on the basis of 901 chemicals tested for toxicity against the luminescent bacteria Vibrio fischeri (formerly Photobacterium phosphoreum, the Microtox® test). The model was created using the Multiple Computer-Automated Structure Evaluation (M-CASE) program. The model can correctly predict acute toxicity for 92% of the compounds with an error averaging 0.55 log units per median effect concentration (EC50). The main toxicophores, corresponding to polar and nonpolar narcosis, and other types of reactive chemicals were identified. [source] Outcome of psychological treatments of pathological gambling: a review and meta-analysisADDICTION, Issue 10 2005Ståle Pallesen ABSTRACT Aims To investigate the short- and long-term effect of psychological treatments of pathological gambling and factors relating to treatment outcome. Design and setting This study provides a quantitative meta-analytical review of psychotherapeutic treatments of pathological gambling. Studies were identified by computer search in the PsycINFO and Medline databases covering the period from 1966 to 2004, as well as from relevant reference lists. Inclusion criteria The target problem was pathological gambling, the treatment was psychological, the study was published in English and outcomes directly pertaining to gambling were employed. Single case studies, studies where elimination of gambling not was the priority and studies with insufficient statistical information were excluded from the present meta-analysis. Participants A total of 37 outcome studies, published or reported between 1968 and 2004, were identified. Of these 15 were excluded, thus 22 studies were included, involving 1434 subjects. The grand mean age was 40.1 years. The overall proportion of men was 71.5%. Measurements The included studies were coded for outcome measures of pathological gambling. For each condition, means and standard deviations for gambling-related outcome measures, all based upon self-reports or therapist ratings, were compiled at three points in time: baseline, post-treatment and the last follow-up reported. Findings Effect sizes represent the difference between the mean score in a treatment condition and a control condition or the difference between mean scores at separated points in time for one group, expressed in terms of standard deviation units. At post-treatment the analysis indicated that psychological treatments were more effective than no treatment, yielding an overall effect size of 2.01 (P < 0.01). At follow-up (averaging 17.0 months) the corresponding effect size was 1.59 (P < 0.01). A multiple regression analysis showed that the magnitude of effect sizes at post-treatment were lower in studies including patients with a formal diagnosis of pathological gambling only, compared to studies not employing such inclusion criteria. Effect sizes were also higher in randomized controlled trials compared to not randomized controlled trials, higher in within subjects designs compared to between subjects designs and also positively related to number of therapy sessions. No mediator variables were significantly related to the magnitude of the effect sizes at follow-up. Conclusion Psychological interventions for pathological gamble seem to be yield very favourable short- and long-term outcomes. [source] Brain Blood-flow Alterations Induced by Therapeutic Vagus Nerve Stimulation in Partial Epilepsy: II.EPILEPSIA, Issue 9 2004Low Levels of Stimulation, Prolonged Effects at High Summary:,Purpose: To measure vagus nerve stimulation (VNS)-induced cerebral blood flow (CBF) effects after prolonged VNS and to compare these effects with immediate VNS effects on CBF. Methods: Ten consenting partial epilepsy patients had positron emission tomography (PET) with intravenous [15O]H2O. Each had three control scans without VNS and three scans during 30 s of VNS, within 20 h after VNS began (immediate-effect study), and repeated after 3 months of VNS (prolonged study). After intrasubject subtraction of control from stimulation scans, images were anatomically transformed for intersubject averaging and superimposed on magnetic resonance imaging (MRI) for anatomic localization. Changes on t-statistical maps were considered significant at p < 0.05 (corrected for multiple comparisons). Results: During prolonged studies, CBF changes were not observed in any regions that did not have CBF changes during immediate-effect studies. During both types of studies, VNS-induced CBF increases were similarly located in the bilateral thalami, hypothalami, inferior cerebellar hemispheres, and right postcentral gyrus. During immediate-effect studies, VNS decreased bilateral hippocampal, amygdalar, and cingulate CBF and increased bilateral insular CBF; no significant CBF changes were observed in these regions during prolonged studies. Mean seizure frequency decreased by 25% over a 3-month period between immediate and prolonged PET studies, compared with 3 months before VNS began. Conclusions: Seizure control improved during a period over which some immediate VNS-induced CBF changes declined (mainly over cortical regions), whereas other VNS-induced CBF changes persisted (mainly over subcortical regions). Altered synaptic activities at sites of persisting VNS-induced CBF changes may reflect antiseizure actions. [source] Synthesis and Monitoring of ,-Bi2Mo3O12 Catalyst Formation using Thermo-Raman SpectroscopyEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2004Anil Ghule Abstract Thermo-Raman spectroscopy was used to monitor the dehydration and phase transformations of Bi2Mo3O12·5H2O. The hydrated forms Bi2Mo3O12·5H2O, Bi2Mo3O12·4.75H2O, Bi2Mo3O12·3H2O, Bi2Mo3O12·2H2O, and anhydrous Bi2Mo3O12 were observed during dehydration in the wavelength range from 200 to 1400 cm,1. Representative Raman spectra of these compounds are reported for the first time. The thermo-Raman intensity thermogram showed a systematic dehydration in four steps, and the differential thermo-Raman intensity thermogram confirmed this. Thermogravimetry, differential thermogravimetry, and differential scanning calorimetry results were in harmony with the results of the thermo-Raman spectroscopy. Additionally, the dehydration resulting in formation of anhydrous Bi2Mo3O12 (amorphous Bi2Mo3O12 phase) and the final transformation into the ,-Bi2Mo3O12 phase was observed to be a dynamic thermal process. The slow, controlled heating rate produced ,-Bi2Mo3O12 catalyst with a particle size averaging 200 nm. The catalyst formed was further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, time of flight SIMS, transmission electron microscopy, and energy-dispersive X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] | |||||||||||||||||||||||||||||||||||||||||||||||||