Thermodynamic Properties of Simple Systems

1993 ◽  
Author(s):  
Greg M. Anderson ◽  
David A. Crerar
Keyword(s):  
Thermodynamic Properties ◽  
Pure Substance ◽  
Energy Term ◽  
Stable States ◽  
Energy Transfers ◽  
Absolute Energy ◽  
The Absolute ◽  
The Difference ◽  
Simple Systems ◽  
Constituent Elements

We have now introduced several thermodynamic parameters that are useful in dealing with energy transfers (U, H, G, etc.). We wish now to see how these quantities are measured and where to find values for them. In later chapters we will see how they are used in detail. However, we have an immediate problem in that we cannot measure the energy parameters U, H, G and A, as discussed in Chapter 4. Because we do not know the absolute values of either the total or molar version of these variables, we are forced to deal only with their changes in processes or reactions of interest to us. But we obviously cannot tabulate these changes for every reaction of potential interest; there are too many. We must tabulate some sort of energy term for each pure substance so that the changes in any reaction between them can be calculated. In the example in §5.7 of water at — 2°C changing to ice at — 2°C, we said that AG was negative. How can we know this without carrying out a research program on the thermodynamic properties of ice and supercooled water? We begin by explaining how this is done. The problem created by not having absolute energy values is handled very conveniently by determining and tabulating, for every pure compound, the difference between the (absolute) G or H of the compound itself and the sum of the (absolute) G or H values of its constituent elements. In other words, AG or AH is determined for the reaction in which the compound is formed from its elements (in their stable states). These differences can be determined experimentally in spite of not knowing the absolute values involved.

Translocation Relative to Range

Methodology ◽  
2008 ◽  
Vol 4 (3) ◽  
pp. 132-138 ◽  
Author(s):  
Michael Höfler
Keyword(s):  
Risk Difference ◽  
Binary Outcomes ◽  
Number Needed To Treat ◽  
Likert Scales ◽  
Psychological Science ◽  
The Absolute ◽  
The Difference ◽  
Variance Parameters ◽  
Standardized Index ◽  
Maximum Possible Magnitude

A standardized index for effect intensity, the translocation relative to range (TRR), is discussed. TRR is defined as the difference between the expectations of an outcome under two conditions (the absolute increment) divided by the maximum possible amount for that difference. TRR measures the shift caused by a factor relative to the maximum possible magnitude of that shift. For binary outcomes, TRR simply equals the risk difference, also known as the inverse number needed to treat. TRR ranges from –1 to 1 but is – unlike a correlation coefficient – a measure for effect intensity, because it does not rely on variance parameters in a certain population as do effect size measures (e.g., correlations, Cohen’s d). However, the use of TRR is restricted on outcomes with fixed and meaningful endpoints given, for instance, for meaningful psychological questionnaires or Likert scales. The use of TRR vs. Cohen’s d is illustrated with three examples from Psychological Science 2006 (issues 5 through 8). It is argued that, whenever TRR applies, it should complement Cohen’s d to avoid the problems related to the latter. In any case, the absolute increment should complement d.

The Issue of Sustainability in Third World Food Production (The Distinguishedl Lecture)

1992 ◽  
Vol 31 (4I) ◽  
pp. 511-534
Author(s):  
Winfried Von Urff
Keyword(s):  
Developing Countries ◽  
Population Growth ◽  
Food Production ◽  
Third World ◽  
Total Population ◽  
Absolute Number ◽  
Comprehensive Analysis ◽  
World Food ◽  
The Absolute ◽  
The Difference

In spite of the fact that food production in developing countries doubled over the last 25 years undernutrition is still widely spread. At the beginning of the eighties, according to FAO, 335 to 494 million people in developing countries suffered from serious undernutrition the difference being due to different concepts to determine undernutrition on which scientist were unable to find a consensus.) Unfortunately there is no recent comprehensive analysis of the food situation comparable to those of previous World Food Surveys but it can be taken for sure that the absolute number of undernourished has increased. According to unofficial FAO sources a figure of 870 million was estimated for 1990 (22 percent of the total population in developing countries) using the same concept that led to the figure of 494 million in 1979-81 (23 percent of the total population in developing countries) which means that most probably the number of undernourished increased at a rate slightly less than population growth.

scholarly journals II. On the electro-chemical equivalent of silver, and on the absolute electromotive force of clark cells

1883 ◽  
Vol 36 (228-231) ◽  
pp. 448-450
Keyword(s):  
Electromotive Force ◽  
British Association ◽  
General Character ◽  
Daily Work ◽  
The Absolute ◽  
The Difference

The investigations upon this subject which have been carried on by Mrs. Sidgwick and myself during the last year and a half, though not yet quite finished, are so far advanced that no doubt remains as to the general character of the results; and as these results have application in the daily work of practical electricians, it is thought desirable to communicate them without further delay. The currents are measured by balancing the attraction and repulsion of coaxal coils against known weights, as described before the British Association in 1882, a method which has fully answered the favourable expectations then expressed. To what was said on that occasion it will be sufficient for the present to add that the readings are taken by reversal of the current in the fixed coils, and the difference of weights thus found (about 1 gram) represents the double force of attraction, free from errors depending upon the connections of the suspended coil, and other sources of disturbance.

scholarly journals A FÉ CRISTÃ NA CONTEMPORANEIDADE: RUMOS E DESAFIOS

2010 ◽  
Vol 41 (115) ◽  
pp. 345
Author(s):  
Maria Clara Lucchetti Bingemer
Keyword(s):  
Christian Theology ◽  
Christian Faith ◽  
Human Being ◽  
Belief In God ◽  
Religious System ◽  
The World ◽  
Important Trend ◽  
The Difference ◽  
Constituent Elements

Diante do panorama extremamente complexo do campo religioso hoje o documento de Aparecida declara estar o ser humano do século XXI em meio a uma “mudança de época”. Ao lado do processo de secularização, que leva o ser humano a não temer declarar sua ausência de crença em Deus e sua não pertença a qualquer sistema religioso, está igualmente o revival” religioso anárquico e selvagem que fez eclodir seitas e novas propostas “espirituais” dos mais variados perfis, questionando em profundidade a decantada supremacia do monoteísmo cristão no Ocidente. A proposta neste artigo é, depois de uma breve análise da situação da religião no mundo e especialmente no Brasil hoje, refletir sobre a diferença entre fé e religião e como esta reflexão, tomada em sua radicalidade, leva a uma compreensão renovada do que seja a fé cristã e sua identidade no mundo atual. Para chegar a isto, são analisados três elementos constitutivos da fé cristã: a historicidade, a experiência e o testemunho, no desejo de traçar um perfil aproximado de uma tendência importante na teologia cristã hoje, que prefere definir o Cristianismo mais como uma revelação do que como uma religião.ABSTRACT: Before the extremely complex panorama of the religious field today the document of Aparecida declares the human being of the XXI century to be in the mist of an “epoch change”. On the side of the secularização process, that leads the human being not to fear in declaring his lack of belief in God and his not belonging to any religious system, there is also the religious anarchical and wild “revival” that brought out sects and new “spiritual” proposals of the most varied profiles, questioning in depth the decanted supremacy of Christian monotheism in the Occident. The proposal of this article is, after a brief analysis of the situation of religion in the world and especially in Brazil today, to reflect on the difference between faith and religion and how this reflection, taken in its radicality, leads to a renewed understanding of what Christian faith is and its identity in the current world. To arrive at this, three constituent elements of the Christian faith are analyzed: the historicity, the experience and the witness, in the desire to trace a profile that approaches an important trend in the Christian theology, which prefers to define Christianity more as a revelation than as a religion.

scholarly journals Intraocular Lens Power Calculation According to the Difference between Anterior and Total Keratometry Using Scheimpflug Imaging

2021 ◽  
Vol 62 (9) ◽  
pp. 1181-1188
Author(s):  
Joong Hee Kim ◽  
Kyong Jin Cho ◽  
Ho Seok Chung
Keyword(s):  
Regression Analysis ◽  
Absolute Error ◽  
Power Calculation ◽  
Intraocular Lens Power Calculation ◽  
Refractive Power ◽  
Simple Regression Analysis ◽  
The Absolute ◽  
The Difference ◽  
Lens Power ◽  
Simple Regression

Purpose: We investigated the change in the absolute error according to the difference between anterior and total keratometry, to determine the criterion for the difference in keratometry, and to determine the indication for using total keratometry. Methods: Sagittal and total refractive power were measured with 2-, 3-, and 4-mm Pentacam® rings, and the absolute error of each was calculated in patients who underwent cataract surgery in our hospital. The correlation between the difference value the sagittal minus the total refractive power and each absolute error was analyzed by simple regression analysis. The analysis was performed by dividing the patients into two groups based on 0.6, which is the average of the difference between the sagittal and total refractive power for the 3-mm ring. Results: Sagittal power was larger than total refractive power for all rings and the absolute error obtained by applying the total refractive power was larger than the sagittal power for the 2- and 4-mm rings (p < 0.001). The simple regression analysis revealed that the absolute error using sagittal power was positively correlated with the difference between sagittal power and total refractive power. In the group with less than 0.6, the absolute error using the total refractive power of all rings was larger than the sagittal power (p < 0.001). In the group exceeding 0.6, the absolute error using the total refractive power was less than using the sagittal power for the 3 mm ring (p = 0.028). Conclusions: The greater the difference between sagittal and total refractive power, the greater the absolute error using sagittal power. Accuracy was higher in the group exceeding 0.6 after applying total refractive power measured at the 3 mm ring compared to sagittal power.

Methodological errors in radioisotope flux measurements

1988 ◽  
Vol 255 (5) ◽  
pp. G696-G699
Author(s):  
R. W. Egnor ◽  
S. G. Vaccarezza ◽  
A. N. Charney
Keyword(s):  
Specific Activity ◽  
Flux Measurement ◽  
Sampling Interval ◽  
Flux Chamber ◽  
Sources Of Error ◽  
Counting Time ◽  
Flux Measurements ◽  
The Absolute ◽  
The Difference ◽  
Serial Samples

We examined several sources of error in isotopic flux measurements in a commonly used experimental model: the study of 22Na and 36Cl fluxes across rat ileal tissue mounted in the Ussing flux chamber. The experiment revealed three important sources of error: the absolute counts per minute, the difference in counts per minute between serial samples, and averaging of serial samples. By computer manipulation, we then applied hypothetical changes in the experimental protocol to generalize these findings and assess the effect and interaction of the absolute counts per minute, the sampling interval, and the counting time on the magnitude of the error. We found that the error of a flux measurement will vary inversely with the counting time and the difference between the consecutive sample counts per minute used in the flux calculations and will vary directly with the absolute counts per minute of each sample. Alteration of the "hot" side specific activity, the surface area of the tissue across which flux is measured and the sample volume have a smaller impact on measurement error. Experimental protocols should be designed with these methodological considerations in mind to minimize the error inherent in measuring isotope flux.

scholarly journals A global algorithm for estimating Absolute Salinity

Ocean Science ◽  
2012 ◽  
Vol 8 (6) ◽  
pp. 1123-1134 ◽  
Author(s):  
T. J. McDougall ◽  
D. R. Jackett ◽  
F. J. Millero ◽  
R. Pawlowicz ◽  
P. M. Barker
Keyword(s):  
Thermodynamic Properties ◽  
North Atlantic ◽  
World Ocean ◽  
Practical Method ◽  
Sea Salt ◽  
The North ◽  
Salinity Anomaly ◽  
The World ◽  
Standard Composition ◽  
The Absolute

Abstract. The International Thermodynamic Equation of Seawater – 2010 has defined the thermodynamic properties of seawater in terms of a new salinity variable, Absolute Salinity, which takes into account the spatial variation of the composition of seawater. Absolute Salinity more accurately reflects the effects of the dissolved material in seawater on the thermodynamic properties (particularly density) than does Practical Salinity. When a seawater sample has standard composition (i.e. the ratios of the constituents of sea salt are the same as those of surface water of the North Atlantic), Practical Salinity can be used to accurately evaluate the thermodynamic properties of seawater. When seawater is not of standard composition, Practical Salinity alone is not sufficient and the Absolute Salinity Anomaly needs to be estimated; this anomaly is as large as 0.025 g kg−1 in the northernmost North Pacific. Here we provide an algorithm for estimating Absolute Salinity Anomaly for any location (x, y, p) in the world ocean. To develop this algorithm, we used the Absolute Salinity Anomaly that is found by comparing the density calculated from Practical Salinity to the density measured in the laboratory. These estimates of Absolute Salinity Anomaly however are limited to the number of available observations (namely 811). In order to provide a practical method that can be used at any location in the world ocean, we take advantage of approximate relationships between Absolute Salinity Anomaly and silicate concentrations (which are available globally).

scholarly journals Absolute colours and phase coefficients of trans-Neptunian objects: correlations and populations

2019 ◽  
Vol 488 (3) ◽  
pp. 3035-3044 ◽  
Author(s):  
Alvaro Alvarez-Candal ◽  
Carmen Ayala-Loera ◽  
Ricardo Gil-Hutton ◽  
José Luis Ortiz ◽  
Pablo Santos-Sanz ◽  
...  
Keyword(s):  
Solar System ◽  
Data Base ◽  
Relative Phase ◽  
Surface Composition ◽  
Dynamical Evolution ◽  
Initial Surface ◽  
Observational Errors ◽  
The Absolute ◽  
The Difference ◽  
Absolute Magnitudes

ABSTRACT The study of the visible colours of the trans-Neptunian objects opened a discussion almost 20 yr ago which, in spite of the increase in the amount of available data, seems far from subside. Visible colours impose constraints to the current theories of the early dynamical evolution of the Solar system such as the environment of formation, initial surface composition, and how (if) they were scattered to regions closer to the inner planets. In this paper, we present an updated version of our data base of absolute colours and relative phase coefficients for 117 objects. We define the absolute colours as the difference of the absolute magnitudes HV − HR, and the relative phase coefficient as the difference of the slopes of the phase curves Δβ. These were obtained joining our own observations plus data from the literature. The methodology has been introduced in previous works and here we expand in some interesting results, in particular the strong anticorrelation found between HV − HR and Δβ, which means that redder objects have steeper phase curves in the R filter, while bluer objects have steeper phase curves in the V filter. We analyse a series of results published in the literature in view of our data base, which is free of phase effects, and show that their statistical meaning is not very strong. We point out that phase-colouring and observational errors play an important role in the understanding of these proposed relationships.

scholarly journals Review of ultraviolet and visual continuum observations and comparisons with Models

1970 ◽  
Vol 36 ◽  
pp. 73-82
Author(s):  
R. C. Bless
Keyword(s):  
Energy Distribution ◽  
Model Atmosphere ◽  
Temperature Scales ◽  
Absolute Energy ◽  
The Absolute

This paper first briefly describes model atmosphere grids now available for comparison with observations. The recent recalibration of the absolute energy distribution of α Lyr substantially improves the agreement of models and observations in the visual. Temperature scales determined by various methods agree reasonably well except for the hottest stars. Recent ultraviolet results suggest that earlier observations of O- and B-type stars indicating large flux deficiencies were probably in error. However, late B- and A-type stars may emit less energy in the UV than that predicted by models which do not include the opacities caused by silicon, magnesium, and carbon.

Oxides, Silicides, and Silicates of Zirconium and Hafnium; Density Functional Theory Study

2002 ◽  
Vol 716 ◽  
Author(s):  
Maciej Gutowski ◽  
John E. Jaffe ◽  
Chun-Li Liu ◽  
Matt Stoker ◽  
Anatoli Korkin
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Gate Dielectric ◽  
Density Functional Theory Calculations ◽  
Heat Of Formation ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Exchange Correlation ◽  
The Difference ◽  
Constituent Elements

AbstractIt is known that the chemistries of hafnium and zirconium are more nearly identical than for any other two congeneric elements. Thus, both zirconia and hafnia, with the dielectric constant K > 20, have emerged as potential replacements for silica (K = 3.9) as a gate dielectric. We report an important difference between the zirconia/Si and hafnia/Si interfaces based on density functional theory calculations with the Perdew-Wang 91 exchange-correlation functional on the oxides, silicides, and silicates of Zr and Hf. The zirconia/Si interface has been found to be unstable with respect to formation of silicides whereas the hafnia/Si interface is stable. The difference between the two interfaces results from the fact that HfO2 is more stable than ZrO2 (i.e. has a larger heat of formation from its constituent elements) by more than 53 kJ/mol. The hafnium silicides, on the other hand, are less stable than zirconium silicides by ca. 20 kJ/mol.

Sign in / Sign up

Export Citation Format

Share Document