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At least 1,405 records · Page 78Linked to original sources
PubMed2005

Clinically significant changes in nausea as measured on a visual analog scale.

STUDY OBJECTIVE: Our objective is to determine the minimum clinically significant change in nausea as measured on a visual analog scale. METHODS: This was a prospective, descriptive, convenience sample study of consenting adults presenting to the emergency department with nausea, excluding intoxicated patients and those with mild nausea (measuring <30 mm on a visual analog scale). Patients rated their nausea severity on a 100-mm visual analog scale and reported whether their nausea was "a lot less," "a little less," "unchanged," "a little more," or "a lot more" compared with previous assessments. We defined the minimum clinically significant change as the mean difference in visual analog scale in patients reporting "a little less" or "a little more" nausea. RESULTS: Eighty-three paired visual analog scale measurements were collected from 50 patients. Fifty-eight percent of patients were women, and the mean age was 41 years. Mean changes in visual analog scale with corresponding qualitative descriptors were "a lot less" in 16 paired measurements (-42.2 mm; 95% confidence interval [CI] -54.9 to -29.5); "a little less" in 34 paired measurements (-15.4 mm; 95% CI -20.0 to -10.8); "no change" in 28 paired measurements (-0.4 mm; 95% CI -5.6 to 4.8); "a little more" in 2 paired measurements (16 mm; 95% CI -86 to 118); and "a lot more" in 3 paired measurements (23.7 mm; 95% CI -5.4 to 52.8). Patients reported "a little more" or "a little less" nausea in 36 paired measurements, with a mean change in visual analog scale of 15.4 mm (95% CI 11.0 to 19.8). CONCLUSION: The minimum clinically significant visual analog scale change in nausea was 15 mm, which is similar to previous studies of other symptoms, and helps in the interpretation of clinical studies reporting changes in nausea.

Adolescent↗
PubMed2005

Validating the Berg Balance Scale for patients with Parkinson's disease: a key to rehabilitation evaluation.

OBJECTIVE: To assess the criterion-related validity of the Berg Balance Scale (BBS) in subjects with Parkinson's disease (PD). DESIGN: Prospective, correlational analysis between the BBS and accepted measures of PD motor and functional impairment. SETTING: The federally funded PD research center, an interdisciplinary center of excellence for people with PD within a Veterans Affairs medical center. PARTICIPANTS: Thirty-eight men (average +/- standard deviation, 71.1+/-10.5 y) with confirmed PD. Their initial diagnosis had been made on average 5.8+/-3.6 years earlier. All could stand or walk unassisted and had mild to moderate disability. Patients who could not ambulate without assistive devices were excluded. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Correlational analyses between the BBS and the Unified Parkinson's Disease Rating Scale (UPDRS) motor scale, Modified Hoehn and Yahr Staging (Hoehn and Yahr) Scale, and the Modified Schwab and England Capacity for Daily Living Scale (S&E ADL Scale). RESULTS: BBS score showed significant correlations with indicators of motor functioning, stage of disease, and daily living capacity. BBS score was inversely associated with the UPDRS motor score (-.58, P <.005), Hoehn and Yahr Scale staging (-.45, P <.005), and S&E ADL Scale rating (.55, P <.005). In all 3 correlations, lower scores on the BBS (indicating greater balance deficits) correlated with higher UPDRS scores (indicating greater motoric or functional impairment). CONCLUSIONS: Results support the criterion-related validity of the BBS. Its utility in other balance conditions of older adults has been established. Rehabilitation interventions have been shown to improve the balance deficits associated with PD. Early referral and periodic reassessment is vital to achieving and maintaining improvements. Our research results agree with other published research in suggesting that the BBS may be used as a screening tool and ongoing assessment tool for patients with PD.

Activities of Daily Living↗
PubMedDate not supplied

Comparison of three rating scales for measuring subjective phenomena in clinical research. I. Use of experimentally controlled auditory stimuli.

BACKGROUND: An interest in measuring subjective phenomena such as pain, nausea, anxiety, etc. has led clinicians to develop three types of ratings: the visual analog scale (VAS); the verbal rating scale (VRS), and the numeric rating score (NRS). These ratings are regarded as global scales because they lack criteria to demarcate diverse dimensions or categories that comprise each scale. The purpose of this study was to evaluate validity and consistency of usage for these scales. Criterion for validity consisted of an experimentally controlled intensity for auditory stimuli. METHODS: We conducted a prospective, experimentally controlled, clinimetric study at the Audiology Department at the Hospital of Puebla Autonomous University (in Puebla State, Mexico). Participants included 25 medical students, two psychology students, and three practicing physicians. Interventions consisted of pure 1,000 Hz tones in five different intensities applied for 3 sec with a 1-min interval between stimuli at three sessions for each observer. Main outcome measure was validity and consistency of usage for VAS, VRS, and NRS scales. RESULTS: Correlation coefficients between scale results and standard stimuli were 0.818 for VAS, 0.735 for NRS, and 0.796 for VRS. Mean weighted kappa indices for intraobserver agreement were 0.70, 0.59, and 0.65, respectively, for scales with five categories each. Mean weighted kappa indices for inter-observer variability were 0.61, 0.48, and 0.54 for VAS, NRS, and VRS again with five categories each. CONCLUSIONS: The three instruments appeared reasonably accurate, with VAS having highest scores. VRS appeared sufficiently consistent to be regarded as providing reliable scientific information.

Acoustic Stimulation↗
PubMed2005

How do pigeons represent numbers? Studies of number scale bisection.

Pigeons' bisection of two number scales, 1-16 and 2-32, was examined in two experiments. In Experiment 1, pigeons learned to choose different comparison keys following 1 or 16 key pecks and 2 or 32 key pecks and then were tested with intermediate numbers of key pecks on nonreinforced probe trials. Psychophysical curves that plotted choice of the large number key against number of pecks showed superposition of the two number scales and indifference between the two keys at the geometric means of each scale. The same procedures were used in Experiment 2, but pigeons were trained to bisect each scale at its arithmetic mean. Two asymmetries appeared in curves that plotted discrimination performance against number: near the midpoints of the scales, accuracy was higher for high numbers than for low numbers, but this relationship reversed at the ends of the scales, with low numbers discriminated more accurately than high numbers. An associative model that assumed stimulus generalization between numbers was used to predict the findings of these two experiments. The model showed a good qualitative fit to the obtained data when it was assumed that number was represented on a log scale and generalization was constant at all numbers but not when it was assumed that number was represented on a linear scale and generalization was scalar.

Animals↗
PubMed2006

A twin study of attention-deficit/hyperactivity disorder dimensions rated by the strengths and weaknesses of ADHD-symptoms and normal-behavior (SWAN) scale.

BACKGROUND: When symptom rating scales are used in the general population, there is severe skewness, with many individuals having no symptoms. While this has major implications for genetic designs that require extremely discordant and concordant (EDAC) siblings, little is known of the genetics of scales which seek to differentiate within the "no ADHD symptom" group. METHODS: Parents of Australian twins completed two attention-deficit/hyperactivity disorder (ADHD) questionnaires, the Australian Twin Behaviour Rating Scale (ATBRS), based on conventional DSM-IV symptom scores, and the Strengths and Weaknesses of ADHD-Symptoms and Normal-Behavior (SWAN) scale, which includes above-average performance on attention and activity. The two scales were compared in two age groups of same-sex twins, 528 pairs aged 6 to 9 and 488 pairs aged 12 to 20. RESULTS: Parents reported higher levels of activity and attention in their twins when reporting using the SWAN scale than when using the ATBRS, and while the monozygotic (MZ) correlations were similar on both scales, the dizygotic (DZ) correlations were consistently higher on the SWAN. On DSM-IV based scales, parents exaggerated differences within those sibling pairs in the "with few ADHD symptoms" category. CONCLUSIONS: The SWAN may provide a more realistic description of the ADHD phenotype for the selection of twin and sibling pairs for genetic analysis.

Adolescent↗
PubMed2005

Scale inhibition study by turbidity measurement.

The concept of a critical supersaturation ratio (CSSR) has been used to characterize the effectiveness of different types of scale inhibitors, inhibitor concentration, and precipitating solution pH in order to prevent the formation of barium sulfate scale. The scale inhibitors used in this work were aminotrimethylene phosphonic acid (ATMP), diethylenetriaminepentamethylene phosphonic acid (DTPMP), and phosphinopolycarboxylic acid polymer (PPCA). The CSSR at which barium sulfate precipitates was obtained as a function of time for different precipitation conditions and was used as an index to evaluate the effect of the precipitation conditions. The results showed that the CSSRs decrease with increasing elapsed time after mixing the precipitating solutions, but increases with increasing scale inhibitor concentration and solution pH. The CSSR varies linearly with the log of the scale inhibitor concentration and with the precipitating solution pH. A SEM analysis showed that the higher the scale inhibitor concentration and solution pH, the smaller and more spherical the BaSO4 precipitates. Analysis of the particle size distribution revealed that increasing the elapsed time, the scale inhibitor concentration, and precipitating solution pH, all produce a broader particle size distribution and a smaller mean diameter of the BaSO4 precipitates. DTPMP and PPCA were the most effective BaSO4 scale inhibitors per ionizable proton and the most effective on a concentration basis, respectively.

Journal Article↗
PubMed2004

Osteoporosis health belief scale: minor changes were required after telephone administration among women.

OBJECTIVE: The Osteoporosis Health Belief Scale (OHBS) is a 42-item scale designed to measure general health motivation, perceived susceptibility to and seriousness of osteoporosis, and beliefs about calcium intake and exercise in preventing and treating osteoporosis. The purpose of this study was to examine the psychometric properties of the OHBS by telephone administration among older women. STUDY DESIGN AND SETTING: A convenience sample of 425 women aged 61-93 years participating in a longitudinal arthritis study was recruited by telephone. Item clarity was evaluated and 22 additional items (6 reworded, 16 from other questionnaires) were considered to supplement or replace existing scale items. Multitrait scaling techniques and exploratory factor analysis were used to test scale structure. Construct validity was tested based on theoretical hypothesis between OHBS subscale scores and participant characteristics. RESULTS: A few modifications to the OHBS scale were suggested, reducing the scale by five items (two redundant, three did not load), rewording one item and moving on item to a different subscale. The modified 37-item OHBS had a seven-factor uncorrelated solution explaining 48% of the model variance with internal consistency ranging from 0.73 to 0.88. CONCLUSION: Relatively minor changes to the OHBS results in reduced redundancy and improved internal structure of the scale for telephone administration among women over 60 years of age. Further examination is recommended to confirm these findings.

Aged↗
PubMed2006

Scaling properties of pyramidal neurons in mice neocortex.

Dendritic morphology is the structural correlate for receiving and processing inputs to a neuron. An interesting question then is what the design principles and the functional consequences of enlarged or shrinked dendritic trees might be. As yet, only a few studies have examined the effects of neuron size changes. Two theoretical scaling modes have been analyzed, conservative (isoelectrotonic) scaling (preserves the passive and active response properties) and isometric scaling (steps up low pass-filtering of inputs). It has been suggested that both scaling modes were verified in neuroanatomical studies. To overcome obvious limitations of these studies like small size of analyzed samples and restricted validity of utilized scaling measures, we considered the scaling problem of neurons on the basis of large sample data and by employing a more general method of scaling analysis. This method consists in computing the morphoelectrotonic transform (MET) of neurons. The MET maps the neuron from anatomical space into electrotonic space using the logarithm of voltage attenuation as the distance metric. The theory underlying this approach is described and then applied to two samples of morphologically reconstructed pyramidal neurons (cells from neocortex of wildtype and synRas transgenic mice) using the NEURON simulator. In a previous study, we could verify a striking increase of dendritic tree size in synRas pyramidal neurons. Surprisingly, in this study the statistical analysis of the sample MET dendrograms revealed that the electrotonic architecture of these neurons scaled roughly in a MET-conserving mode. In conclusion, our results suggest only a minor impact of the Ras protein on dendritic electroanatomy, with non-significant changes of most regions of the corresponding METs.

Algorithms↗
PubMed2005

The decision evaluation scales.

There are several instruments to assess how patients evaluate their medical treatment choice. These are used to evaluate decision aids. Our objective is to investigate which psychological factors play a role when patients evaluate their medical treatment choices. A pool of 36 items was constructed, covering concepts such as uncertainty about and satisfaction with the decision, informed choice, effective decision making, responsibility for the decision, perceived riskiness of the choice, and social support regarding the decision. This pool was presented to patients at high risk for breast and ovarian cancer, awaiting a genetic test result, and facing the choice between prophylactic surgery or screening. Additional measures were assessed for validation purposes. Factor and Rasch analyses were used for factor and item selection. Construct validity of emerging scales was assessed by relating them with the additional measures. Three factors summarised the psychological factors concerning decision evaluation: Satisfaction-Uncertainty, Informed Choice, and Decision Control. Reliabilities (Cronbach's alpha) of the three scales were 0.79, 0.85, and 0.75, respectively. Construct validity hypotheses were confirmed. The first two scales were similar to previously developed scales. Of these three scales, the Decision Control scale correlated most strongly with the well-being measures, was associated with partner's agreement and physician's preferences as perceived by patients, and with a negative emotional reaction to the information material. In conclusion, the Decision Control scale is a new scale to evaluate decision aids, and it appears to be rooted in health psychological theories.

Adult↗
PubMed2005

Calcium mobilization from fish scales is mediated by parathyroid hormone related protein via the parathyroid hormone type 1 receptor.

The scales of bony fish represent a significant reservoir of calcium but little is known about their contribution, as well as of bone, to calcium balance and how calcium deposition and mobilization are regulated in calcified tissues. In the present study we report the action of parathyroid hormone-related protein (PTHrP) on calcium mobilization from sea bream (Sparus auratus) scales in an in vitro bioassay. Ligand binding studies of piscine 125I-(1-35(tyr))PTHrP to the membrane fraction of isolated sea bream scales revealed the existence of a single PTH receptor (PTHR) type. RT-PCR of fish scale cDNA using specific primers for two receptor types found in teleosts, PTH1R, and PTH3R, showed expression only of PTH1R. The signalling mechanisms mediating binding of the N-terminal amino acid region of PTHrP were investigated. A synthetic peptide (10(-8) M) based on the N-terminal 1-34 amino acid residues of Fugu rubripes PTHrP strongly stimulated cAMP synthesis and [3H]myo-inositol incorporation in sea bream scales. However, peptides (10(-8) M) with N-terminal deletions, such as (2-34), (3-34) and (7-34)PTHrP, were defective in stimulating cAMP production but stimulated [3H]myo-inositol incorporation. (1-34)PTHrP induced significant osteoclastic activity in scale tissue as indicated by its stimulation of tartrate-resistant acid phosphatase. In contrast, (7-34)PTHrP failed to stimulate the activity of this enzyme. This activity could also be abolished by the adenylyl cyclase inhibitor SQ-22536, but not by the phospholipase C inhibitor U-73122. The results of the study indicate that one mechanism through which N-terminal (1-34)PTHrP stimulates osteoclastic activity of sea bream scales, is through PTH1R and via the cAMP/AC intracellular signalling pathway. It appears, therefore, that fish scales can act as calcium stores and that (1-34)PTHrP regulates calcium mobilization from them; it remains to be established if this mechanism contributes to calcium homeostasis in vivo.

Animals↗
PubMed2006

Mapping of spatial multi-scale sources of arsenic variation in groundwater on ChiaNan floodplain of Taiwan.

This study applied multivariate factorial kriging to derive the characteristics of the spatial variations of groundwater arsenic distributions at different scales on the ChiaNan floodplain, Taiwan. Seven variables (dissolved oxygen, oxidation-reduction potential, alkalinity, sulfate, iron cations, manganese cations and total organic carbon) and Arsenic were adopted to analyze the mechanisms of arsenic enrichments in groundwater. The hydrogeological environment had spatial and quantitative influences on arsenic enrichments at different scales. The regional scale was set to 32 km referring to the extension distance of flow paths to reflect the effects of flushing in the aquifer, while the local scale was set to 16 km referring to the farthest distance of seawater intrusion to determine the influence of seawater intrusion. The results of factorial kriging suggested that arsenic releases resulted partially from pyrite oxidation during the flushing at the regional scale and partially due to the siderite dissolution at the local scale. Overall, the alkalinity dominated arsenic distribution in groundwater at both the regional and local scales. The multivariate factorial kriging results also demonstrated that seawater intrusion slightly affected the increase of arsenic in groundwater, accounting for only 17.3% of total variation. However, the interaction of seawater intrusion and arsenic distribution in space indicated that seawater intrusion restrained the distribution of arsenic from the areas where seawater was located. High dissolved oxygen was found at where over-pumping induced drawdown cones occurred and also limited the spatial variation of arsenic. Our findings indicate that multivariate factorial kriging can be a useful mapping tool to improve understanding of the mechanism of arsenic release in groundwater at different scales. And the results conducted from the application of multivariate factorial kriging in southwestern Taiwan reveal the important influences of the hydrogeological processes, either artificial or natural, on the arsenic variations in groundwater.

Arsenic↗
PubMed2004

An ecological framework linking scales across space and time based on self-thinning.

Scaling up from measurements made at small spatial and short temporal scales is a central challenge in the ecological and related sciences, where predictions at larger scales and over long time periods are required. It involves two quite distinct aspects: a formulation of a theoretical framework for calculating space-time averages, and an acquisition of data to support that framework. In this paper, we address the theoretical part of the question, and although our primary motivation was an understanding of carbon accounting our formulation is more general. To that end, we adopt a dynamical systems approach, and incorporate a new dynamical formulation of self-thinning. We show how to calculate rates of change for total (and average) plant dry mass, volume, and carbon, in terms of the properties of the individual plants. The results emphasize how local scale statistics (such as, variation in the size of individuals) lead to nonlinear variation at larger scales. Further, we describe how regular and stochastic disturbance can be readily incorporated into this framework. It is shown that stochastic disturbance at patch-scales, results in (to first approximation) regular disturbance at ecosystem scales, and hence can be formulated as such. We conclude that a dynamical formulation of self-thinning can be used as a generic framework for scaling ecological processes in space and time.

Ecosystem↗
PubMed2000

Optimal number of response categories in rating scales: reliability, validity, discriminating power, and respondent preferences.

Using a self-administered questionnaire, 149 respondents rated service elements associated with a recently visited store or restaurant on scales that differed only in the number of response categories (ranging from 2 to 11) and on a 101-point scale presented in a different format. On several indices of reliability, validity, and discriminating power, the two-point, three-point, and four-point scales performed relatively poorly, and indices were significantly higher for scales with more response categories, up to about 7. Internal consistency did not differ significantly between scales, but test-retest reliability tended to decrease for scales with more than 10 response categories. Respondent preferences were highest for the 10-point scale, closely followed by the seven-point and nine-point scales. Implications for research and practice are discussed.

Adolescent↗
PubMed2004

Comparison of pressure ulcer grading scales: a study of clinical utility and inter-rater reliability.

Pressure ulcer grading scales are subjective measures of pressure damage. This study measured inter-observer agreement of the Stirling scale (1-digit and 2-digit versions) and the European Pressure Ulcer Advisory Panel Scale, using Cohen's kappa and percentage agreement. Clinical utility was also assessed. Thirty-five observations were made by two Registered Nurses on 30 adult in-patients. The levels of agreement obtained were better than those reported previously and this may be related to the methodology used. The 2-digit Stirling scale gave the best level of chance corrected agreement (kappa=0.457) and was the scale preferred by raters. The 1-digit Stirling scale performed least favourably. Qualitative data identified problems with scale construction relating to visualisation of the base of the wound, discolouration of the skin, abrasions and shallow ulcers. Whilst refinements in scale construction may improve rater reliability, there is a need to develop objective measures of pressure induced tissue damage.

Adult↗
PubMed2000

Spatial scale of visual analysis for vernier acuity does not vary over time.

The visual system filters spatial pattern through a range of narrowly tuned spatial mechanisms, but the rules by which the outputs of these mechanisms are combined across time to extract precise geometrical information are not yet clear. One hypothesis is that spatial analysis shifts over time from coarse to finer spatial scales, in order to extract fine spatial information. An alternative hypothesis is that thresholds are determined by the signal-to-noise ratio within an optimal spatial scale. In this study, we measured vernier acuity across exposure duration for equally visible long lines and short lines and found no improvement in spatial precision with time. Using a simultaneous spatial-masking paradigm, we determined the active spatial scales at 100 and 1000 ms. The results show no significant changes in spatial scale, or in the size-range of active scales, for the two exposure durations. Furthermore, whereas vernier thresholds vary markedly with line contrast, we find only modest shifts in spatial scale. Taken together, our results suggest that for vernier acuity, spatial scale is selected very early, and that vernier thresholds are predominantly limited by signal strength within that spatial scale.

Humans↗
PubMed1998

The use of the Panic and Agoraphobia Scale in a clinical trial.

A new scale for assessing severity in PDA (Panic Disorder with/without Agoraphobia) has recently been developed: the Panic and Agoraphobia Scale [P & A (Bandelow, 1995)]. The objective of this study was to test whether the scale is sensitive to changes during a treatment trial. Thirty-seven patients (mean age, 32.7; S.D., 6.3) with PDA were treated with imipramine (75-150 mg/day) for 8 weeks in an open prospective trial. Patients with concurrent agoraphobia were instructed in practising self-exposure to agoraphobic situations. The total scores on the P & A, the Hamilton Anxiety Scale (HAMA) and the Clinical Global Impression Scale (CGI) were used as the main efficacy criteria. Treatment results were excellent, as could be shown by a decrease in the average severity scores of the P & A observer-rated version from 28.9 (S.D., 8.1) to 13.3 (S.D., 11.8; rank statistic T(N) = 6.7; P < 0.0001). The largest effect size r(w) of all clinician-rated scales was seen with the observer-rated version of the P & A, although closely followed by the CGI and the HAMA. Among the self-rated scales, the P & A (self-rated version) also showed the largest effect size. All five subscores of the P & A showed significant improvements. The highest treatment effect sizes could be seen in the 'panic attacks' subscore, followed by the 'anticipatory anxiety' subscore. The new Panic and Agoraphobia Scale (P & A) is a useful tool for measuring treatment efficacy in panic disorder trials.

Adult↗
PubMed2001

Physiological responses to mixing in large scale bioreactors.

Escherichia coli fed-batch cultivations at 22 m3 scale were compared to corresponding laboratory scale processes and cultivations using a scale-down reactor furnished with a high-glucose concentration zone to mimic the conditions in a feed zone of the large bioreactor. Formate accumulated in the large reactor, indicating the existence of oxygen limitation zones. It is suggested that the reduced biomass yield at large scale partly is due to repeated production/re-assimilation of acetate from overflow metabolism and mixed acid fermentation products due to local moving zones with oxygen limitation. The conditions that generated mixed-acid fermentation in the scale-down reactor also induced a number of stress responses, monitored by analysis of mRNA of selected stress induced genes. The stress responses were relaxed when the cells returned to the substrate limited and oxygen sufficient compartment of the reactor. Corresponding analysis in the large reactor showed that the concentration of mRNA of four stress induced genes was lowest at the sampling port most distant from the feed zone. It is assumed that repeated induction/relaxation of stress responses in a large bioreactor may contribute to altered physiological properties of the cells grown in large-scale bioreactor. Flow cytometric analysis revealed reduced damage with respect to cytoplasmic membrane potential and integrity in cells grown in the dynamic environments of the large scale reactor and the scale-down reactor.

Acetic Acid↗
PubMed2002

Estimation of local scale dispersion from local breakthrough curves during a tracer test in a heterogeneous aquifer: the Lagrangian approach.

The local scale dispersion tensor, Dd, is a controlling parameter for the dilution of concentrations in a solute plume that is displaced by groundwater flow in a heterogeneous aquifer. In this paper, we estimate the local scale dispersion from time series or breakthrough curves, BTCs, of Br concentrations that were measured at several points in a fluvial aquifer during a natural gradient tracer test at Krauthausen. Locally measured BTCs were characterized by equivalent convection dispersion parameters: equivalent velocity, v(eq)(x) and expected equivalent dispersivity, [lambda(eq)(x)]. A Lagrangian framework was used to approximately predict these equivalent parameters in terms of the spatial covariance of log(e) transformed conductivity and the local scale dispersion coefficient. The approximate Lagrangian theory illustrates that [lambda(eq)(x)] increases with increasing travel distance and is much larger than the local scale dispersivity, lambda(d). A sensitivity analysis indicates that [lambda(eq)(x)] is predominantly determined by the transverse component of the local scale dispersion and by the correlation scale of the hydraulic conductivity in the transverse to flow direction whereas it is relatively insensitive to the longitudinal component of the local scale dispersion. By comparing predicted [lambda(eq)(x)] for a range of Dd values with [lambda(eq)(x)] obtained from locally measured BTCs, the transverse component of Dd, DdT, was estimated. The estimated transverse local scale dispersivity, lambda(dT) = DdT/U1 (U1 = mean advection velocity) is in the order of 10(1)-10(2) mm, which is relatively large but realistic for the fluvial gravel sediments at Krauthausen.

Chemical Phenomena↗