Factors Affecting Sampling Variability of Freshwater Periphyton and the Power of Periphyton Studies

1992 ◽  
Vol 49 (8) ◽  
pp. 1695-1703 ◽  
Author(s):  
Antoine Morin ◽  
Antonella Cattaneo
Keyword(s):  
Dry Mass ◽  
Mean Value ◽  
Sampling Unit ◽  
Sampling Effort ◽  
Sampling Variability ◽  
Factors Affecting ◽  
Artificial Streams ◽  
Size Type ◽  
The Mean ◽  
Strong Relationships

Estimates of periphyton abundance, biomass (as biovolume, chlorophyll, dry mass, or ash-free dry mass), and production were reanalyzed to examine the effect of the mean value, sampler size, type of substratum, and habitat on the variance of these estimates. There were strong relationships between the variance and the mean for all variables considered. Variability per sampling unit increased with sampler size for all variables except production and biovolume, which were both unaffected. Chlorophyll estimates were significantly less variable on artificial than on natural substrata, but this trend was not confirmed by other variables. For biovolume, the trend was reversed. Habitat affects periphyton variability only for some variables: production was more variable in streams than in lakes whereas chlorophyll was less variable in artificial streams than in any other habitat. Although periphyton tends to be less patchy than benthos, detection of small differences still requires a very intense sampling effort. Since the median replication is 3–10 in most published studies, only large differences can be detected with 95% probability, from twofold for the most precise variable (biovolume) to eightfold for the less precise variable (dry mass). Our ability to detect patterns in periphyton ecology is thus very limited.

scholarly journals 2D-shear wave elastography: number of acquisitions can be reduced according to clinical setting

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marco Dioguardi Burgio ◽  
Jules Grégory ◽  
Maxime Ronot ◽  
Riccardo Sartoris ◽  
Gilles Chatellier ◽  
...  
Keyword(s):  
Shear Wave ◽  
Liver Stiffness ◽  
Shear Wave Elastography ◽  
Mean Value ◽  
Factors Affecting ◽  
Absolute Value ◽  
Factors Associated ◽  
Supersonic Shear Imaging ◽  
The Mean ◽  
The Difference

Abstract Background The factors affecting intra-operator variability of two-dimensional shear wave elastography (2D-SWE) have not been clearly established. We evaluated 2D-SWE variability according to the number of measurements, clinical and laboratory features, and liver stiffness measurements (LSM). Methods At least three LSM were performed in 452 patients who underwent LSM by 2D-SWE (supersonic shear imaging) out of an initial database of 1650 patients. The mean value of the three LSM was our best measurement method. Bland–Altman plots were used to evaluate intra-operator variability when considering only one, or the first two measurements. Variability was assessed by taking the absolute value of the difference between the first LSM and the mean of the three LSM. Logistic regression was used to assess the factors associated with the highest tertile of variability. Results The limit of agreement was narrower with the mean of the first and second measurements than with each measurement taken separately (− 2.83 to 2.99 kPa vs. − 5.86 to 6.21 kPa and − 5.77 to 5.73 kPa for the first and second measurement, respectively). A BMI ≥ 25 kg/m2 and a first LSM by 2D-SWE ≥ 7.1 kPa increased the odds of higher variability by 3.4 and 3.9, respectively. Adding a second LSM didn’t change the variability in patients with BMI < 25 and a first LSM by 2D-SWE < 7.1 kPa. Conclusions Intra-operator variability of LSM by 2D-SWE increases with both a high BMI and high LSM value. In patients with BMI < 25 kg/m2 and a first LSM < 7.1 kPa we recommend performing only one LSM.

THE DISTRIBUTION OF GROOMING AMONG FEMALE PRIMATES: TESTING HYPOTHESES WITH THE SHANNON-WIENER DIVERSITY INDEX

Behaviour ◽  
2000 ◽  
Vol 137 (11) ◽  
pp. 1517-1540 ◽  
Author(s):  
Mario S. Di Bitetti
Keyword(s):  
Social Relationships ◽  
Group Size ◽  
Adult Female ◽  
Diversity Index ◽  
Mean Value ◽  
Female Group ◽  
Sampling Effort ◽  
Data Set ◽  
Wiener Diversity Index ◽  
The Mean

AbstractThe Shannon-Wiener diversity index (H) has been used to characterize grooming relationships among adult female primates. To make comparisons among different groups, the value of H has been divided by the maximum value it can reach for a particular group size. This ratio, the grooming diversity ratio (GDR), has been used to test predictions from hypotheses that may explain the distribution of social relationships among adult female primates. Using grooming data from different primate populations and random computer simulations I show that the mean value of H and GDR are positively affected by the ln of the mean number of grooming bouts recorded per dyad (LnMNBD) and negatively by the coefficient of variation in the frequency of grooming bouts recorded for the females within a group (CV). These two variables reflect the combined effect of sampling effort and the rate of interactions among individuals (and their variance) and should be statistically controlled to make sensible use of H or GDR. After controlling for LnMNBD and CV, I found no significant effect of female group size, the degree of female involvement in inter-group encounters and the patterns of female dispersal on the mean value of GDR. The socioecological model of female social relationships (Sterck et al., 1997) predicts that groups categorized as resident-egalitarian should have higher GDRs than resident-nepotistic ones. I find some support for this prediction when using a data set where some species contributed more than one data point but not when using mean values per species as in the previous analyses. This result may be confounded by a phylogenetic effect: langurs seem to have more diverse relationships than other primates. Data from more species are necessary to corroborate these results and to disentangle the effect of phylogeny from that of the social categories since most monkey groups characterized as resident-egalitarian were langurs.

Measured Distributions of Control Delay on Signalized Arterials

2003 ◽  
Vol 1852 (1) ◽  
pp. 1-9 ◽  
Author(s):  
James D. Colyar ◽  
Nagui M. Rouphail
Keyword(s):  
Real World ◽  
Standard Error ◽  
Mean Value ◽  
Signal Timing ◽  
Factors Affecting ◽  
Highway Capacity Manual ◽  
Control Delay ◽  
Signal Coordination ◽  
Before And After ◽  
The Mean

The Highway Capacity Manual and other traffic operations manuals give no guidance on the magnitude and factors affecting variability in control delay. However, knowing the variability in control delay has several useful applications, such as providing a more complete and statistically significant comparison of different signal timing or roadway geometric improvements. The objective of this research is to provide an exploratory analysis of the variability in signalized control delay using real-world measurements on an arterial corridor in Cary, North Carolina. Data were collected with a portable, onboard emissions and engine diagnostics measurement device, from which second-by-second speed data were recorded. A new method for estimating intersection control delay from second-by-second speed data is presented that attempts to take into account over-capacity conditions and closely spaced intersections. The data collection focused on recording a similar number of runs on a corridor before and after signal coordination was implemented. The results show that the distribution of control delay generally has a single, large peak at low delays, when the mean control delay was in the level-of-service A–B range, whereas the distribution becomes increasingly bimodal (two distinct peaks) as the mean control delay increases. Another finding is that there is a direct relationship between mean control delay and standard error of control delay, but there is still variability in the standard error that cannot be explained solely by the mean value. Finally, differences in the before and after runs showed that a real-world signal timing improvement can reduce both the mean and the standard error of control delay as well as alter the shape of the delay distribution.

scholarly journals Anxiety of patients undergoing ct imaging in emergency department

2017 ◽  
Vol 3 (1) ◽  
pp. 43 ◽  
Author(s):  
Eyaggelia Kakagianni ◽  
Martha Kelesi-Stauropoulou ◽  
Eleni Dokoutsidou ◽  
Ourania Govina
Keyword(s):  
Emergency Department ◽  
Stress Management ◽  
Mean Value ◽  
Intervention Programs ◽  
Factors Affecting ◽  
General Anxiety ◽  
Significant Difference ◽  
The Mean ◽  
Convenience Sampling ◽  
The Many

Introduction: The performance of computed tomography (CT) causes anxiety and discomfort to patients and increases the overall psychological burden.Aim: The purpose of the present study was to investigate the anxiety of patients undergoing CT when entering in the Emergency Department (ED).Material and Methods: To achieve the research objectives was conducted primary research in the ED of a General Hospital of Athens. The research was based on Convenience sampling and the data collected by a self-completion questionnaire during the period May to September 2016. The study sample consisted of 150 people. The State - Trait Anxiety Inventory (STAI) was the questionnaire of this study.Results: The mean value of the current anxiety was 58.70(± 7.32), while the general anxiety was 39.77 (± 7.32), with statistically significant difference (p <0.001). The majority of patients were very anxious prior to performing the CT. In contrast, patients do not feel special stress and anxiety in their lives in general. The factors affecting the current anxiety of patients attending ED and are to undergo CT were: age, education level, marital status, previous experience, cause of examination and presence of pain.Conclusions: One of the many challenges to be faced by health professionals is the stress management of the patient prior of the CT. The organization of intervention programs will positively contribute to the stress management and outcomes of patients.

scholarly journals Factors Affecting Microcuttings ofSteviaUsing a Mist-Chamber Propagation Box

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Mohamad Osman ◽  
Nur Syamimi Samsudin ◽  
Golam Faruq ◽  
Arash Nezhadahmadi
Keyword(s):  
Stevia Rebaudiana ◽  
Mean Value ◽  
Diabetic Patients ◽  
Data Logger ◽  
Indole Butyric Acid ◽  
Factors Affecting ◽  
Medicinal Value ◽  
The Mean ◽  
Mist Chamber ◽  
Root Stimulation

Stevia rebaudianaBertoni is a member of Compositae family.Steviaplant has zero calorie content and its leaves are estimated to be 300 times sweeter than sugar. This plant is believed to be the most ideal substitute for sugar and important to assist in medicinal value especially for diabetic patients. In this study, microcutting techniques using a mist-chamber propagation box were used as it was beneficial for propagation ofSteviaand gave genetic uniformity to the plant. The effects of different treatments on root stimulation ofSteviain microcuttings technique were evaluated. Treatments studied were different sizes of shoot cuttings, plant growth regulators, lights, and shades. Data logger was used to record the mean value of humidity (>90% RH), light intensity (673–2045 lx), and temperature (28.6–30.1°C) inside the mist-chamber propagation box. From analysis of variance, there were significant differences between varieties and treatments in parameters studied (P<0.05). For the size of shoot cuttings treatment, 6 nodes cuttings were observed to increase root number. As compared to control, shoot cuttings treated with indole butyric acid (IBA) had better performance regarding root length. Yellow light and 50% shade treatments showed higher root and leaf number and these conditions can be considered as crucial for potential propagation ofStevia.

Long-period modulated superstructures in Pd-12.5 at.%Ce and Pd-15 at.%Ce alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 164-165
Author(s):  
Noriyuki Kuwano ◽  
Masaru Itakura ◽  
Kensuke Oki
Keyword(s):  
Electron Microscopy ◽  
Mean Value ◽  
Heavy Elements ◽  
Arc Furnace ◽  
X Ray ◽  
Long Period ◽  
Ultra High Purity ◽  
Heat Treated ◽  
Atomic Scattering ◽  
The Mean

Pd-Ce alloys exhibit various anomalies in physical properties due to mixed valences of Ce, and the anomalies are thought to be strongly related with the crystal structures. Since Pd and Ce are both heavy elements, relative magnitudes of (fcc-fpd) are so small compared with <f> that superlattice reflections, even if any, sometimes cannot be detected in conventional x-ray powder patterns, where fee and fpd are atomic scattering factors of Ce and Pd, and <f> the mean value in the crystal. However, superlattices in Pd-Ce alloys can be analyzed by electron microscopy, thanks to the high detectability of electron diffraction. In this work, we investigated modulated superstructures in alloys with 12.5 and 15.0 at.%Ce.Ingots of Pd-Ce alloys were prepared in an arc furnace under atmosphere of ultra high purity argon. The disc specimens cut out from the ingots were heat-treated in vacuum and electrothinned to electron transparency by a jet method.

Partition Coefficient Ratios and Tumour Perfusion Studied with 85mKr and 133Xe

1987 ◽  
Vol 26 (06) ◽  
pp. 253-257
Author(s):  
M. Mäntylä ◽  
J. Perkkiö ◽  
J. Heikkonen
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Regional Blood Flow ◽  
Blood Perfusion ◽  
Compartmental Analysis ◽  
Malignant Tumour ◽  
Mean Value ◽  
Perfusion Rate ◽  
Biological Variables ◽  
The Mean

The relative partition coefficients of krypton and xenon, and the regional blood flow in 27 superficial malignant tumour nodules in 22 patients with diagnosed tumours were measured using the 85mKr- and 133Xe-clearance method. In order to minimize the effect of biological variables on the measurements the radionuclides were injected simultaneously into the tumour. The distribution of the radiotracers was assumed to be in equilibrium at the beginning of the experiment. The blood perfusion was calculated by fitting a two-exponential function to the measuring points. The mean value of the perfusion rate calculated from the xenon results was 13 ± 10 ml/(100 g-min) [range 3 to 38 ml/(100 g-min)] and from the krypton results 19 ± 11 ml/(100 g-min) [range 5 to 45 ml/(100 g-min)]. These values were obtained, if the partition coefficients are equal to one. The equations obtained by using compartmental analysis were used for the calculation of the relative partition coefficient of krypton and xenon. The partition coefficient of krypton was found to be slightly smaller than that of xenon, which may be due to its smaller molecular weight.

Detection of Soluble Fibrin Monomer Complexes in Blood by Means of Protamine Sulphate Test

1968 ◽  
Vol 20 (01/02) ◽  
pp. 044-049 ◽  
Author(s):  
B Lipiński ◽  
K Worowski
Keyword(s):  
Human Subjects ◽  
Coronary Thrombosis ◽  
Mean Value ◽  
Healthy Human ◽  
Protamine Sulphate ◽  
Soluble Fibrin ◽  
Fibrin Monomer ◽  
Dog Plasma ◽  
The Mean ◽  
Precipitable Protein

SummaryIn the present paper described is a simple test for detecting soluble fibrin monomer complexes (SFMC) in blood. The test consists in mixing 1% protamine sulphate with diluted oxalated plasma or serum and reading the optical density at 6190 Å. In experiments with dog plasma, enriched with soluble fibrin complexes, it was shown that OD read in PS test is proportional to the amount of fibrin recovered from the precipitate. It was found that SFMC level in plasma increases in rabbits infused intravenously with thrombin and decreases after injection of plasmin with streptokinase. In both cases PS precipitable protein in serum is elevated indicating enhanced fibrinolysis. In healthy human subjects the mean value of OD readings in plasma and sera were found to be 0.30 and 0.11, while in patients with coronary thrombosis they are 0.64 and 0.05 respectively. The origin of SFMC in circulation under physiological and pathological conditions is discussed.

Detection of Circulating Tissue Factor and Factor VII in a Normal Population

1996 ◽  
Vol 75 (05) ◽  
pp. 772-777 ◽  
Author(s):  
Sybille Albrecht ◽  
Matthias Kotzsch ◽  
Gabriele Siegert ◽  
Thomas Luther ◽  
Heinz Großmann ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Normal Population ◽  
Mean Value ◽  
Factor Vii ◽  
Significant Difference ◽  
Age Dependent ◽  
The Mean ◽  
Highly Correlated ◽  
And Gender

SummaryThe plasma tissue factor (TF) concentration was correlated to factor VII concentration (FVIIag) and factor VII activity (FVIIc) in 498 healthy volunteers ranging in age from 17 to 64 years. Immunoassays using monoclonal antibodies (mAbs) were developed for the determination of TF and FVIIag in plasma. The mAbs and the test systems were characterized. The mean value of the TF concentration was 172 ± 135 pg/ml. TF showed no age- and gender-related differences. For the total population, FVIIc, determined by a clotting test, was 110 ± 15% and the factor VIlag was 0.77 ± 0.19 μg/ml. FVII activity was significantly increased with age, whereas the concentration demonstrated no correlation to age in this population. FVII concentration is highly correlated with the activity as measured by clotting assay using rabbit thromboplastin. The ratio between FVIIc and FVIIag was not age-dependent, but demonstrated a significant difference between men and women. Between TF and FVII we could not detect a correlation.

Determination of Plasminogen in Clots and Thrombi

1966 ◽  
Vol 16 (01/02) ◽  
pp. 038-050 ◽  
Author(s):  
Ulla Hedner ◽  
Inga Marie Nilsson ◽  
B Robertson
Keyword(s):  
Mean Value ◽  
Main Mechanism ◽  
Clot Lysis ◽  
Post Mortem ◽  
Digestion Time ◽  
Normal Volunteers ◽  
Casein Solution ◽  
The Mean

SummaryThe plasminogen content was determined by a casein method in plasma and serum from 20 normal volunteers. The mean plasminogen content was found to be 10.1 ACU (the arbitrary caseinolytic unit defined in such a way that using a 3% casein solution and a digestion time of 20 min. at 37°C, 10 ACU gave an extinction of 0.300). No difference between serum and plasma regarding the plasminogen content was found.Plasminogen was determined in drained and drained plus washed clots prepared from 2 ml plasma. The highest values found in the drained clots were 0.9 ACU/clot and 0.2 ACU/clot in the drained plus washed clots.Plasminogen was also determined in drained and drained plus washed clots prepared from plasma with added purified plasminogen. The plasminogen was recovered in the washing fluid. According to these tests, then, purified added plasminogen is washed out of the clots.The plasminogen content of 20 thrombi obtained post mortem was also determined. The mean value was found to be 0.7 ACU/cm thrombus. Judging from our results, the “intrinsic clot lysis theory” is not the main mechanism of clot dissolution.

Sign in / Sign up

Export Citation Format

Share Document