Research Note: Calibration of micropipettes for pressure-probe studies

1998 ◽  
Vol 25 (8) ◽  
pp. 947
Author(s):  
Ricardo Murphy ◽  
Joseph K.E. Ortega
Keyword(s):  
Water Relation ◽  
Mean Value ◽  
Independent Method ◽  
Pressure Probe ◽  
Cell Water ◽  
Mean Values ◽  
Capillary Tubing ◽  
Oil Water ◽  
Water Meniscus

In order to determine cell water-relation parameters with the pressure probe, the ratio of inner to outer pipette diameters (α = Di/Do) must be estimated. Four different methods for estimating a were compared. I: measurement of the volume of oil expelled from a pipette and the corresponding movement of an oil/water meniscus within the pipette; II: measurement of Di and Do on fractured pipettes; III: measurement of Di and Do on intact pipettes; IV: measurement of Di and Do on capillary tubing. Methods I and II gave mean values for α (± SE) that were in excellent agreement [0.587 ± 0.004 (n = 12), and 0.593 ± 0.003 (n = 14), respectively]. Method III gave variable results for Do < 80µm; for Do > 80 µm a mean value α = 0.624 ±0.007 (n = 4) was obtained. Method IV gave a mean value α = 0.544 ± 0.001 (n = 5). It is suggested that any method for calibrating micropipettes should be checked against an independent method (e.g. Method I) that allows the determination of α for Do < 100 µm. In the present study, Method II gave the best combination of accuracy and convenience.

scholarly journals The Effect of Alteration of Vertical Dimension of Occlusion on Brain Activity in Complete Denture Wearers

2021 ◽  
Vol 9 (D) ◽  
pp. 108-112
Author(s):  
Ayman A. Elmorsy ◽  
Mohamed Zaki ◽  
Hafiz Elbahnaswi ◽  
Amani R. Moussa ◽  
Asmaa N. Elboraey
Keyword(s):  
Brain Activity ◽  
Mean Value ◽  
Vertical Dimension ◽  
Mean Values ◽  
Significance Level ◽  
Before And After ◽  
Edentulous Patients ◽  
Electroencephalogram Eeg ◽  
Alpha Waves

BACKGROUND: The establishment of appropriate vertical dimension of occlusion (VDO) is paramount for successful and functioning complete dentures (CDs). AIM: The aim of this study was to assess the effect of alteration of VDO on the brain activity in CD wearers. MATERIALS AND METHODS: Ten completely edentulous patients participated in this study. Each patient received three sets of CDs: one control set and two duplicates’ CDs. The control CDs was designed with appropriate VDO (control - VDO), while the duplicate CDs were designated as followed: one with VDO lowered by –3 mm (low - VDO) the other one VDO was increased by +5 mm (high - VDO). The effect of alteration of VDO on brain activity was assessed by measuring alpha waves changes using electroencephalogram (EEG) before and after chewing gum. Statistical analysis was carried out using one-way ANOVA and dependent t-test. The significance level was set at p < 0.05. RESULTS: There was a significant increase in the alpha waves mean values after chewing (p < 0.05) gum compared to before except for low - VDO CDs (p > 0.05). The control-VDO revealed a statistically significant higher mean values compared to the duplicate dentures. CDs with high - VDO showed higher mean value than low - VDO dentures, however, it was statistically insignificant (p > 0.05). CONCLUSION: Appropriate determination of VDO is not only important for the success of CDs but also for the functional augmentation of brain activity.

Effect of Low O2 Concentration and Azide on Hydraulic Conductivity and Osmotic Volume of the Cortical Cells of Wheat Roots

1991 ◽  
Vol 18 (6) ◽  
pp. 603 ◽  
Author(s):  
WH Zhang ◽  
SD Tyerman
Keyword(s):  
Hydraulic Conductivity ◽  
Pressure Probe ◽  
Cortical Cells ◽  
Wheat Roots ◽  
Volume Relaxation ◽  
Pressure Relaxation ◽  
Mean Values ◽  
O2 Concentration ◽  
Relaxation Experiments

The short-term effects of O2 deficiency and sodium azide (NaN3) on the hydraulic conductivity of cortical cells in wheat roots was studied using the pressure probe. Hydraulic conductivities were obtained by measuring either turgor relaxation, or volume relaxation under pressure clamp. Both low O2 concentration and NaN3 increased the half times of pressure and volume relaxations. The increases in T½ were found to be due to a decrease in the hydraulic conductivity (Lp) of the cells. The mean values of Lp from pressure relaxation experiments were 7.75 × 10-1m s-1 Mpa-1 in the fully aerated solution and 1.15 and 2.17 x 10-1m s-1 Mpa-1 in low O2 concentration and 1 mol m-3 NaN3 solutions respectively. The pressure clamp experiments yielded similar results to pressure relaxation experiments for both low O2 concentration and 1 mol m-3 NaN3 treatments. In addition to determination of Lp, pressure and volume relaxation experiments were also used to evaluate osmotic volume of the cells. In aerated solutions the osmotic volume of the cells was about twice that of their geometric volume, but in low O2 concentration and NaN3 solutions the osmotic cell volume was reduced and approximately equal to the geometric volume. The decrease in osmotic volume and part of the reduction in Lp may be explained by the occlusion of plasmodesmata induced by low O2 concentration and NaN3.

scholarly journals The difference-periodogram—a method for the rapid determination of short periodicities

1924 ◽  
Vol 105 (731) ◽  
pp. 346-359 ◽  
Keyword(s):  
Rapid Determination ◽  
Mean Value ◽  
Half Cycle ◽  
Mean Values ◽  
The Third ◽  
The Mean ◽  
The Difference ◽  
Periodic Components ◽  
Similar Phase

The examination of a long series of observations in the search for periodicities by harmonic analysis is a tedious process. The method outlined below, although rough, has the merit of being much more rapid in its application, and has been found useful in the preliminary exploration of long meteorological records of periodic or quasi-periodic components. It is also useful in the study of periodicities of intermittent recurrence or variable length. The basis of the method is the division of a series of observations into series which are nearly, but not quite, equal, to half the length of the suspected periodicity. If each section were exactly half the periodicity the first, third, fifth, etc., sections would all occur in the same position relatively to the periodic curve, while the second, fourth, sixth, etc., would occur a half-cycle away. If each section is slightly less than half the length of the periodicity, then the third and so on, until after a certain interval the n th section occurs at a similar phase to the first. The number of sections required to bring this about depends on the relation between their length and the length of the periodicity. If the sections selected had been slightly longer than half the periodicity, the phase would advance somewhat between the first and third sections, and so on until the cycle was repeated. Thus by plotting the mean values of all the odd sections and drawing a curve through them we could obtain an idea of the length of the underlying periodicity. The even sections could be plotted in the same way, and if the series of observations were completely be the reverse of each other. Thus by substituting for the mean value of each section its difference from the mean of the whole series, and reversing the sign of all the even sections, we can bring the latter into line with the odd sections and draw a single curve representing all the observations.

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.

Determination of the Probability Distribution of the Mean Sound Level

2010 ◽  
Vol 35 (4) ◽  
pp. 543-550 ◽  
Author(s):  
Wojciech Batko ◽  
Bartosz Przysucha
Keyword(s):  
Probability Distribution ◽  
Probability Distribution Function ◽  
Mean Value ◽  
Sound Level ◽  
Function Form ◽  
Noise Levels ◽  
Logarithmic Mean ◽  
The Mean ◽  
Estimation Of Uncertainty

AbstractAssessment of several noise indicators are determined by the logarithmic mean <img src="/fulltext-image.asp?format=htmlnonpaginated&src=P42524002G141TV8_html\05_paper.gif" alt=""/>, from the sum of independent random resultsL1;L2; : : : ;Lnof the sound level, being under testing. The estimation of uncertainty of such averaging requires knowledge of probability distribution of the function form of their calculations. The developed solution, leading to the recurrent determination of the probability distribution function for the estimation of the mean value of noise levels and its variance, is shown in this paper.

Seasonal trends in the stable isotopic composition of snow and meltwater runoff in a subarctic catchment at Okstindan, Norway

2004 ◽  
Vol 35 (2) ◽  
pp. 119-137 ◽  
Author(s):  
S.D. Gurney ◽  
D.S.L. Lawrence
Keyword(s):  
Isotopic Composition ◽  
Mean Value ◽  
Mean Values ◽  
Stable Isotopic Composition ◽  
Meltwater Runoff ◽  
Stable Isotopic ◽  
The Mean ◽  
The Difference ◽  
Δ18o And Δd

Seasonal variations in the stable isotopic composition of snow and meltwater were investigated in a sub-arctic, mountainous, but non-glacial, catchment at Okstindan in northern Norway based on analyses of δ18O and δD. Samples were collected during four field periods (August 1998; April 1999; June 1999 and August 1999) at three sites lying on an altitudinal transect (740–970 m a.s.l.). Snowpack data display an increase in the mean values of δ18O (increasing from a mean value of −13.51 to −11.49‰ between April and August), as well as a decrease in variability through the melt period. Comparison with a regional meteoric water line indicates that the slope of the δ18O–δD line for the snowpacks decreases over the same period, dropping from 7.49 to approximately 6.2.This change points to the role of evaporation in snowpack ablation and is confirmed by the vertical profile of deuterium excess. Snowpack seepage data, although limited, also suggest reduced values of δD, as might be associated with local evaporation during meltwater generation. In general, meltwaters were depleted in δ18O relative to the source snowpack at the peak of the melt (June), but later in the year (August) the difference between the two was not statistically significant. The diurnal pattern of isotopic composition indicates that the most depleted meltwaters coincide with the peak in temperature and, hence, meltwater production.

The Natural Radioactivity in Food: A Comparison Between Different Feeding Regimes

2019 ◽  
Vol 15 (5) ◽  
pp. 493-499 ◽  
Author(s):  
Francesco Caridi ◽  
Santina Marguccio ◽  
Alberto Belvedere ◽  
Maurizio D`Agostino ◽  
Giovanna Belmusto
Keyword(s):  
Vegetable Oils ◽  
Natural Radioactivity ◽  
Specific Activity ◽  
Mean Value ◽  
Vegetable Food ◽  
Fish Samples ◽  
Feeding Regimes ◽  
Italian Origin ◽  
Dose Levels

Background: In this article a comprehensive study was carried out for the determination of natural radioactivity in animal and vegetable food (meat, fish, milk and derivates, legumes, cereals and derivates, fruit, hortalizas, vegetables, vegetable oils) typical of different feeding regimes, for the age category higher than 17 years. Methods: A total of eighty-five samples of Italian origin, coming from large retailers during the years 2014, 2015 and 2016, were analyzed through HPGe gamma spectrometry. Results: The specific activity of 40K was investigated and its mean value was found to be: (106.3 ± 6.9) Bq/kg for bovine, swine and sheep meat; (116.5 ± 9.7) Bq/kg for fish; (52.9 ± 3.1) Bq/kg for milk and derivates; (271.9 ± 16.7) Bq/kg for legumes; (67.2 ± 4.7) Bq/kg for cereals and derivates; (52.7 ± 4.4) Bq/kg for fruit; (72.9 ± 5.6) Bq/kg for hortalizas; (83.9 ± 6.5) Bq/kg for vegetables; lower than the minimum detectable activity for vegetable oils. For animal food the highest mean 40K activity concentration was found in fish samples; for vegetable food the highest one was detected in legumes. Conclusion: The evaluation of dose levels due to the food ingestion typical of Mediterranean, Vegetarian and Vegan diets was performed. The annual effective dose was found to be 0.16 mSv/y, 0.41 mSv/y and 0.54 mSv/y, respectively.

Polarizability and nonpolarizability of oil-water interfaces with relevance to a.c. impendance measurements

1991 ◽  
Vol 56 (1) ◽  
pp. 112-129 ◽  
Author(s):  
Takashi Kakiuchi ◽  
Mitsugi Senda
Keyword(s):  
Charge Transfer ◽  
Numerical Calculation ◽  
Supporting Electrolyte ◽  
Water Interface ◽  
Migration Effect ◽  
Ac Current ◽  
Stationary Interface ◽  
Oil Water ◽  
Anion Transfer

We have estimated the degree of polarizability of a polarized oil-water interface used as a working interface and that of the nonpolarizability of a nonpolarized interface used as a reference oil-water interface from the numerical calculation of dc and ac current vs potential behavior at both interfaces. Theoretical equations of dc and ac currents for simultaneous cation and anion transfer of supporting electrolytes have been derived for the planar stationary interface for reversible and quasi-reversible cases. In the derivation, the migration effect and the coupling of the cation and anion transfer have been incorporated. The transfer of ions constituting a supporting electrolyte contributes to the total admittance of the interface even in the region where the interface may be considered as polarized in dc sense, as pointed out first by Samec et al. (J. Electroanal. Chem. 126, 121 (1981)). Moreover, the reference oil-water interface is not ideally reversible, so that the contribution from this interface to the measured admittance cannot be negligible, unless the area of the reference oil-water interface is much larger than that of the working oil-water interface. The effect of non-ideality of the reference oil-water interface on the determination of double layer capacitances and kinetic parameters of charge transfer at the working oil-water interface has been estimated.

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