Determination of the water regulation capacity of a typic hapludands by means of humidity retention curves and the modeling of its hydrophysical properties

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
Cindy L. Argote-Sanchez ◽  
Juliana M. Lozano-Santa ◽  
Aldemar Reyes-Trujillo
Keyword(s):  
Organic Matter ◽  
Laboratory Finding ◽  
High Capacity ◽  
Water Regulation ◽  
A Value ◽  
Best Fitting ◽  
The Mean ◽  
Valle Del Cauca ◽  
Fitting Model

In the watershed Centella , located in the upper river basin of the Dagua - Valle del Cauca, in nine farms with association coffee - banana, coffee - guamo, cane panelera and pastures, the water regulation capacity of the soil was studied by means of humidity retention curves obtained in the laboratory and by modeling its hydrophysical properties in Hydrus 2D. Properties such as texture, bulk density, porosity, organic matter, hydraulic conductivity, infiltration and humidity were determined. Subsequently, moistureretention curves were simulated using the hydraulic models of Van Genuchten, Brooks and Corey, Van Genuchten modified and Kosugi, evaluating the average errors and the dispersion of the data. Agreed to the results it is possible to point out that the soil under study has a high capacity for moisture retention ( > 18%), consequence of the high content of clays ( > 41%) and organic matter ( > 5%), characteristics of the Andisols of the Valle del Cauca. Finally, the best fitting model was compared statistically with the data of the curves obtained in the laboratory, finding that Van Genuchten and Van Genuchten models modified, are the most appropriate for obtaining the retention curves from the hydrophysical properties since they presented a lower mean error (ME) with a value not higher than -0.11 cm3 / cm3 and a value of the square root of the mean square error (RMSE) less than 0.11 cm3 / cm3.

Regulatory Agency Acceptance of the Interpretation of the Freezing Point Value of Milk as Part of the Official Thermistor Cryoscopic Method

1970 ◽  
Vol 53 (3) ◽  
pp. 539-542
Author(s):  
R W Henningson
Keyword(s):  
Milk Sample ◽  
North American ◽  
Freezing Point ◽  
Sample Survey ◽  
Regulatory Agencies ◽  
A Value ◽  
Added Water ◽  
The Mean ◽  
Definition Of

Abstract A 1968 North American authentic milk sample survey determined that the mean freezing point value of milk is –0.5404°C. Statistical concepts permit the calculation of a value, –0.525°C, 2.326 standard deviations from a mean with 95% confidence that 99% of all subsequent observations will be below the value. Based on this survey, it was recommended that the Interpretation of the freezing point value of milk be made a part of the official final action thermistor cryoscopic method for the determination of the freezing point value of milk, and include the following: an upper limit for the freezing point value of milk, an official definition of an authentic milk sample, and a logical procedure for the confirmation of added water. A copy of the report and an explanatory letter were sent to approximately 100 North American regulatory agencies. Reports were received from 49 regulatory agencies with 39 favoring the recommendations, 6 opposing the recommendations, and 4 having no opinion. It is recommended that the Interpretation of the freezing point of milk be included in both the thermistor cryoscopic and the Hortvet methods.

Least-squares Analysis of Fabric Data: A Note on Conical, Cylindroidal and Near–cylindroidal Folds

1971 ◽  
Vol 8 (6) ◽  
pp. 694-697 ◽  
Author(s):  
C. S. Venkitasubramanyan
Keyword(s):  
Least Squares ◽  
Stereographic Projection ◽  
Rotation Axis ◽  
Computational Procedure ◽  
Apical Angle ◽  
Small Circle ◽  
Best Fitting ◽  
Fabric Diagrams ◽  
The Mean

A cylinder and a plane may be considered as special limiting cases for a right circular cone as the semi-apical angle approaches 0° and 90° respectively (Loudon 1964, Kelley 1966). If these forms are viewed as surfaces generated by an array of lines in space, the rotation axis for the array (the axis of the "cone") can be determined from the orientations of the surface-generating lines by a single computational procedure, using least-squares criterion. The mean angle between the rotation axis and the surface-generating lines will be the semi-apical angle of the cone. However, if this method for determination of the semi-apical angle of the cone, and therefore the best-fitting small circle, is extended to fabric diagrams, in which an array of lines may only statistically describe a great circle or small circle on a stereographic projection, ambiguities arise in certain cases and the semi-apical angle obtained may not be the true semi-apical angle. The difficulty arises because the poles to foliation surfaces are arbitrarily assigned "senses".

scholarly journals 34. Meteor mass distribution from underdense-trail echoes

1968 ◽  
Vol 33 ◽  
pp. 362-372 ◽  
Author(s):  
M. Šimek ◽  
B.A. McIntosh
Keyword(s):  
High Power ◽  
Statistical Error ◽  
Total Sample ◽  
Logarithmic Scale ◽  
Line Density ◽  
A Value ◽  
Electron Line ◽  
The Mean ◽  
Image Position

The amplitude of meteor echoes is recorded on a logarithmic scale by a high-power radar equipment (λ = 9·2 m, PT=3 MW, G = 5·6) at Springhill Meteor Observatory near Ottawa. The smallest amplitude measured corresponds to a pulse power of 10−12 W, which represents a minimum electron line density of about 7 × 1011 el/m or a radio magnitude of + 10.Distribution curves of number of echoes as a function of echo power have been obtained from some 50 samples of 500 meteors each, at various times of day on about 1 day per month. The slopes showed little variation throughout the year. The statistical error in the slope value for any one sample was small, ~ 2–3%. However, determination of the mass index s from these slopes involves several problems. On the basis of simplest theory we have obtained for the sporadic background, with no definite seasonal or diurnal variation.During shower periods, lower values of s were obtained. For the 1966 Leonids, s for the shower was determined by estimating the percentage of shower meteors in the total sample. A value s = 1·7 ± 0·1 was obtained as the mean of 6 samples. It is not known to what extent the height-ceiling effect influences the observation of this shower.

scholarly journals Defining normal jugular venous pressure with ultrasonography

CJEM ◽  
2010 ◽  
Vol 12 (04) ◽  
pp. 320-324 ◽  
Author(s):  
Steven J. Socransky ◽  
Ray Wiss ◽  
Ron Robins ◽  
Alexandre Anawati ◽  
Marc-Andre Roy ◽  
...  
Keyword(s):  
Physical Examination ◽  
Interrater Reliability ◽  
Venous Pressure ◽  
Jugular Venous Pressure ◽  
Normal Range ◽  
Convenience Sample ◽  
A Value ◽  
The Mean ◽  
Research Assistants

ABSTRACT Objective: Determination of jugular venous pressure (JVP) by physical examination (E-JVP) is unreliable. Measurement of JVP with ultrasonography (U-JVP) is easy to perform, but the normal range is unknown. The objective of this study was to determine the normal range for U-JVP. Methods: We conducted a prospective anatomic study on a convenience sample of emergency department (ED) patients over 35 years of age. We excluded patients who had findings on history or physical examination suggesting an alteration of JVP. With the head of the bed at 45°, we determined the point at which the diameter of the internal jugular vein (IJV) began to decrease on ultrasonography (“the taper”). Research assistants used 2 techniques to measure U-JVP in all participants: by measuring the vertical height (in centimetres) of the taper above the sternal angle, and adding 5 cm; and by recording the quadrant in the IJV's path from the clavicle to the angle of the jaw in which the taper was located. To determine interrater reliability, separate examiners measured the U-JVP of 15 participants. Results: We successfully determined the U-JVP of all 77 participants (38 male and 39 female). The mean U-JVP was 6.35 (95% confidence interval 6.11–6.59) cm. In 76 participants (98.7%), the taper was located in the first quadrant. Determination of interrater reliability found κ values of 1.00 and 0.87 for techniques 1 and 2, respectively. Conclusion: The normal U-JVP is 6.35 cm, a value that is slightly lower than the published normal E-JVP. Interrater reliability for U-JVP is excellent. The top of the IJV column is located less than 25% of the distance from the clavicle to the angle of the jaw in the majority of healthy adults. Our findings suggest that U-JVP provides the potential to reincorporate reliable JVP measurement into clinical assessment in the ED. However, further research in this area is warranted.

scholarly journals 47. Cosmology

1976 ◽  
Vol 16 (3) ◽  
pp. 137-157
Author(s):  
M. S. Longair
Keyword(s):  
Deceleration Parameter ◽  
Hubble Constant ◽  
Density Parameter ◽  
Massive Galaxies ◽  
A Value ◽  
The Mean ◽  
Points Of View ◽  
The Universe

A major procedural advance in the determination of the H0 and Ω has been that the problem is now being attacked from many different points of view and to some extent the observations are converging on preferred values of H0 and Ω (Ω = density parameter = 8πGρ0/3H0 where ρ0 is the mean density of matter in the Universe and H0 is the Hubble constant; Ω = 2q0 where q0 is the deceleration parameter). The classical approaches through the redshift-magnitude relation for the most massive galaxies in clusters suggest a value of H0 = 60 km s-1 Mpc (see the review by Tammann in IAU Symp. 63).

scholarly journals IV. A determination of the electromotive force of the weston normal cell in semi-absolute volts

1914 ◽  
Vol 214 (509-522) ◽  
pp. 147-198 ◽  
Keyword(s):  
Electromotive Force ◽  
Order Of Accuracy ◽  
Absolute Determination ◽  
A Value ◽  
Great Progress ◽  
The Mean ◽  
The Absolute ◽  
The Times ◽  
Made In

The measurement of the E. M. F. of the Weston cell affords the best means of comparing the performances of different methods and instruments for the absolute determination of the ampere. Great progress has been made in the last six years, but the most recent determinations by independent methods, giving equal promise of accuracy, still show discrepancies covering a range of 2 parts in 10,000, which must be debited for the most part to the difficulty of the absolute determination of current. Each method in itself appears to give an order of accuracy of repetition approaching, or even exceeding, 1 in 100,000. It is therefore of special interest and importance to compare the results of methods differing as widely as possible in experimental details in endeavouring to arrive at a value comparatively free from the constant errors which may beset any particular type of method. The measurements described by Mr. Shaw in the following paper were made by the method of the Weber bifilar electrodynamometer, as modified by Clerk Maxwell and Latimer Clark, which has not hitherto been employed for work of the highest accuracy, and which merits attention on account of its many fundamental points of difference from recent methods. The instrument originally supplied to McGill College for this purpose was a faithful copy of Clerk Maxwell’s instrument at Cambridge, of which the theory is given together with a figure and description in his ‘ Electricity and Magnetism,’ vol, 2, p. 367. The chief sources of error in this instru­ment were (1) the uncertainty of insulation of the coils, which proved to be of the order of nearly one half of 1 per cent.; (2) the difficulty of determining the mean radii of the coils, which were wound with silk-covered wire; (3) the want of rigidity of the pulley arrangement for equalising the tensions of the suspending wires, and the imperfect elasticity of the control, which depended too much on torsion, and made it impossible to obtain readings consistent to 1 in 1000 for the deflections or the times of oscillation. These defects were so fatal to accurate work even of the order of 1 in 10,000, which was all that it was originally contemplated, that it was found necessary to reconstruct the instrument entirely until nothing remained of the original except the frame, and even that required stiffening to a material extent.

scholarly journals Asteroid Masses and Densities

1971 ◽  
Vol 12 ◽  
pp. 33-39 ◽  
Author(s):  
Joachim Schubart
Keyword(s):  
Total Mass ◽  
Direct Determination ◽  
Absolute Magnitude ◽  
Strong Increase ◽  
Minor Planets ◽  
Solar Mass ◽  
A Value ◽  
The Mean ◽  
The Masses

Before 1966, when Hertz (1966) published his first direct determination of the mass of Vesta, all our knowledge on asteroid masses was based on estimates. The masses of the first four minor planets resulted from the measured diameters by Barnard (1900) (see the paper by Dollfus in this volume) and from estimated mean densities. The diameters of the smaller objects were derived from their brightness and an estimate of their reflectivity (usually the reflectivity of the Moon was adopted). In 1901, Bauschinger and Neugebauer (1901) derived a value for the total mass of the first 458 asteroids. All the diameters were computed from the brightness with an assumed value for the reflectivity. The diameter of Ceres found in this way is very close to Barnard’s (1900) value. The mean density of the 458 asteroids was put equal to that of Earth, and their total mass resulted as 3 X 10-9 solar mass. Stracke (1942) used the same method with an increased material, but the addition of more than 1000 faint asteroids did not bring a significant change in the estimate of the total mass. The report on the McDonald asteroid survey (Kuiper et al., 1958) does not contain another estimate of the total mass of the asteroid ring, but it points to the possibility of a very rapid increase in the number of asteroids with decreasing absolute brightness. If this increase is strong enough, each interval of 1 mag in absolute magnitude can contribute the same amount to the total mass. In the range of magnitudes covered by the Palomar-Leiden survey (PLS) (van Houten et al., 1970), there are no indications for such a strong increase.

Caractéristiques isotopiques (18O, 13CO2, 3H) des écoulements dans une tourbière sur pergélisol au Nouveau-Québec

1982 ◽  
Vol 19 (6) ◽  
pp. 1255-1263 ◽  
Author(s):  
Laurent Dever ◽  
Michelle Laithier ◽  
Claude Hillaire-Marcel
Keyword(s):  
Organic Matter ◽  
Water Flow ◽  
Residence Time ◽  
Lag Time ◽  
Temperature Relationship ◽  
Mean Annual Temperature ◽  
Hydraulic Characteristics ◽  
A Value ◽  
Winter Snow

The 18O – mean annual temperature relationship, which is known in organic matter, presents some anomalies in Sphagnum. A study of water flow and isotopic characteristics of an arctic mire (Leaf River, Ungava Peninsula) has been undertaken to explain these anomalies. The isotopic compositions of the water (18O, 13CO2, 3H) permit the determination of some hydraulic characteristics of a peat on permafrost: (1) evaluation of the lag time between a rainfall and the discharge; (2) evaluation of the residence time of the water; and (3) subsequent mixing parts. A relationship between the isotopic characteristics and the ombrotrophic or minerotrophic nature of the mire is observed. A δ18O value of −11‰ appears in the ombrotrophic zone and a value of −17‰ in the minerotrophic zone. The relative enrichment in 18O of the first one indicates a shorter residence time. The isotopic changes subsequent to rainfalls (with δ18O = −12.2, −14.5, and −19.1‰ differ in time and space: (1) a 2‰ change is observed within 24 h in the minerotrophic zone; (2) a 6‰ change appears almost instantaneously in the ombrotrophic zone. 3H values indicate that neither the meltwater from winter snow (with low 3H content), nor the meltwater from permafrost participates in the subsurface flow.

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