Contributions of ventilation and perfusion inhomogeneities to the VA/Q distribution

1992 ◽  
Vol 72 (6) ◽  
pp. 2298-2304 ◽  
Author(s):  
T. A. Wilson ◽  
K. C. Beck
Keyword(s):  
Vertical Gradient ◽  
The Other ◽  
Independent Data ◽  
Frequency Distributions ◽  
Highly Correlated ◽  
Using Data ◽  
Additional Variance ◽  
Exchange Data ◽  
Ventilation And Perfusion ◽  
Vertical Gradients

The anatomic distributions of ventilation (VA) and perfusion (Q) in prone and supine dogs have been described in the literature. These data also provide frequency distributions, i.e., the distribution of lung units as a function of VA or Q. A comprehensive distribution that encompasses these two distributions is described, and the properties of the comprehensive distribution that determine the width of the VA/Q distribution are identified. Using data on the VA and Q distributions taken from various sources in the literature, we estimated the widths of the VA/Q distributions. The widths estimated from the independent data on the VA and Q distributions agree well with the widths obtained from gas exchange data. The analysis provides information about the relative contributions of the VA and Q distributions to the width of the VA/Q distribution. In the prone dog, the VA and Q distributions, as described by the available data, have different length scales, and we argue that these distributions are therefore not highly correlated. As a result, the variance of the VA/Q distributions is approximately the sum of the variances of the VA and Q distributions. Two-thirds of the variance in VA/Q is a result of nonuniform Q, and one-third is a result of nonuniform VA. In the supine dog, the variance of VA is larger than in the prone dog because of a vertical gradient and the variance of Q is larger, in part, because of a vertical gradient. Because the magnitudes of the vertical gradients of VA and Q are about equal, the vertical gradient of VA/Q is small, and these components of the VA and Q inhomogeneities contribute little to the width of the VA/Q distribution. The other components of Q inhomogeneity cause the additional variance of VA/Q in the supine dog.

Properties of random functions

1956 ◽  
Vol 52 (4) ◽  
pp. 672-686 ◽  
Author(s):  
D. S. Palmer
Keyword(s):  
Cross Correlation ◽  
The Other ◽  
Horizontal Line ◽  
Time Lags ◽  
Frequency Distributions ◽  
Random Functions ◽  
Wave Radio ◽  
Long Wave ◽  
Radio Signals ◽  
Highly Correlated

ABSTRACTThis paper deals with the relationships of the maxima, minima and zeros of two random functions of known autocorrelations and cross-correlation, based on the work of Rice(4). Ratcliffe(3) and Briggs and Spencer(2) discuss a similar problem in connexion with a ‘Phillips Record’ of an experiment in ionospheric reflexion. In this experiment there are two highly correlated reflected signals, their maxima coming close together, and the record shows the time lags between a maximum on one signal and a maximum on the other. Briggs and Page (1) have made an experimental study of the distribution of the differences between the positions of the maxima of two highly correlated random functions, using EDSAC to construct the functions. In §§ 3–7 the frequency distributions of intervals between successive zeros and maxima, and of the lengths of intercepts by a horizontal line, are considered. This has applications to the study of the fading of long-wave radio signals, where the tune differences between successive maxima of the amplitude have been investigated.

SOIL MORPHOLOGY AND SOIL PHYSICAL PROPERTIES. I. SOIL AERATION

1972 ◽  
Vol 52 (3) ◽  
pp. 311-321 ◽  
Author(s):  
K. W. AYRES ◽  
R. G. BUTTON ◽  
E. DE JONG
Keyword(s):  
Soil Structure ◽  
Regression Coefficient ◽  
The Other ◽  
Soil Morphology ◽  
Soil Horizons ◽  
Undisturbed Soil ◽  
Soil Aeration ◽  
Structural Types ◽  
Highly Correlated ◽  
Undisturbed Soil Cores

The relation between soil structure and soil aeration was investigated on undisturbed soil cores from soil horizons exhibiting six distinct kinds of soil structure (prismatic, columnar, blocky, granular, platy, massive) over a broad range of soil texture. Soil aeration was characterized at ⅓ atm suction by measurements of air porosity, relative diffusivity (D/Do) and the rate of oxygen diffusion to a platinum microelectrode (ODR). Aeration was adequate in most of the Chernozemic soil horizons studied; however, aeration in many of the Bnt horizons of the Solonetzic soils was inadequate. Air porosity and D/Do were highly correlated. The regression coefficient for D/Do vs. air porosity for blocky structures was significantly different from that found for the other five structural types. For granular structures a negative correlation was found for ODR vs. air porosity compared with a low positive correlation found for the other structure types.

Foreign Aid and its Role in Maintaining the Exploitation of the Agricultural Sector: Evidence from a Case Study in Africa

1983 ◽  
Vol 13 (1) ◽  
pp. 33-49 ◽  
Author(s):  
Claudio Schuftan
Keyword(s):  
Rural Development ◽  
Foreign Aid ◽  
Local Governments ◽  
Agricultural Sector ◽  
National Development ◽  
The Other ◽  
Sizable Proportion ◽  
Using Data ◽  
State Of Affairs

Today most foreign aid donors are genuinely committed to the idea that development in Third World countries should start with rural development. Therefore, a sizable proportion of their development funds are invested in rural projects. However, donors channel these funds through local governments (most often representing local bourgeois interests) that are not as committed to the principle of rural development. These governments are often also embarked in policies that are actually—directly or indirectly—expropriating the surpluses generated by agriculture and investing them in the other sectors of the economy. The peasants are therefore footing most of the bill of overall national development. This paper contends that, because of this state of affairs, foreign aid directed toward rural development is actually filling the investment gap left by an internal system of unequal returns to production in agriculture. In so doing, foreign aid is indirectly financing the development of the other sectors of the economy, even if this result is unintended. This perpetrates maldevelopment without redressing the basic exploitation process of peasants which lies at the core of underdevelopment. Evidence to support this hypothesis is presented using data from a primarily agricultural exporting country: the United Republic of Cameroon.

Examining the validity of three methods of measuring pre-readers’ knowledge of storybook events

2021 ◽  
pp. 026565902199554
Author(s):  
Lynn Dempsey
Keyword(s):  
The Other ◽  
Narrative Comprehension ◽  
Important Predictor ◽  
Story Comprehension ◽  
Typically Developing ◽  
Typically Developing Children ◽  
Event Knowledge ◽  
Yield Information ◽  
Highly Correlated ◽  
Planning Intervention

Planning intervention for narrative comprehension deficits requires a thorough understanding of a child’s skill in all component domains. The purpose of this study was to examine the validity of three methods of measuring pre-readers’ event knowledge, an important predictor of story comprehension. Thirty-eight typically developing children (12 males; 26 females) between the ages of 30–59 months ( M = 42.05 SD = 7.62) completed three measures – verbal account, enactment, picture-sequencing – that tapped their knowledge of two different events before listening to stories based on each of those events and completing story comprehension tasks. Scores for verbal account and enactment, but not for picture sequencing, (1) were moderately correlated with comprehension scores for the corresponding story; (2) reflected differential knowledge of the two events, though not in the expected direction; (3) were moderately correlated with one another in the case of each story. In general measures for the same event were more highly correlated with one another than with measures of the other event. Overall, results suggest that verbal account and enactment may yield information useful for clinicians planning intervention for children with narrative comprehension deficits.

A New Test of Auditory-Visual Integration

1973 ◽  
Vol 36 (3_suppl) ◽  
pp. 1063-1066 ◽  
Author(s):  
Andrew H. Gregory ◽  
H. Margaret Gregory
Keyword(s):  
Reading Ability ◽  
The Other ◽  
Nonverbal Intelligence ◽  
Visual Integration ◽  
Morse Form ◽  
Highly Correlated

Two auditory-visual integration tests were given to 86 children from 6 yr. to 11 yr. One test was basically that developed by Birch; the other used Morse-type stimuli. The children were also given tests of nonverbal intelligence, reading and vocabulary. With age and intelligence partialled out, the Morse form of test was significantly more highly correlated with reading ability than the Birch test. Reasons are suggested as to why the Morse version may be a better test of some of the underlying skills involved in reading.

Estimation of Construction Waste Generation and Management in Taiwan

2011 ◽  
Vol 243-249 ◽  
pp. 6292-6295 ◽  
Author(s):  
Rong Yau Huang ◽  
Li Hsu Yeh ◽  
Hao Hsien Chen ◽  
Jyh Dong Lin ◽  
Ping Fu Chen ◽  
...  
Keyword(s):  
Decision Tree ◽  
Cross Correlation ◽  
Expert Interviews ◽  
Waste Generation ◽  
Valid Conclusion ◽  
Construction Waste ◽  
Composition Ratio ◽  
The Past ◽  
Highly Correlated ◽  
Using Data

This study examines construction waste generation and management in Taiwan. We verify the factors probable affecting the output of construction wastes by using data for the output of declared construction wastes produced from demolition projects in Taiwan in the last year, expert interviews, and research achievements in the past, and find “ on-site separation” is the factor with effects on the output of construction wastes via cross-correlation by algorithms such as K-Means and Decision Tree C5.0. It can be seen that the output (0.092(t/M3) with on-site separation or 0.329(t/M3) without on-site separation is highly correlated with the composition ratio of construction wastes and referred to as a valid conclusion.

The Semantic Differential as an Index of Traffic Sign Perception and Comprehension

1977 ◽  
Vol 19 (2) ◽  
pp. 183-189 ◽  
Author(s):  
Robert E. Dewar ◽  
Jerry G. Ells
Keyword(s):  
Semantic Differential ◽  
The Other ◽  
Traffic Sign ◽  
Two Factors ◽  
Valid Instrument ◽  
Paper And Pencil ◽  
Verbal Messages ◽  
Highly Correlated

There is a need to develop and validate simple, inexpensive techniques for the evaluation of traffic sign messages. This paper examines the semantic differential (a paper-and-pencil test which measures psychological meaning) as a potential instrument for such evaluation. Two experiments are described, one relating semantic differential scores to comprehension and the other relating this index to glance legibility. The data indicate that semantic differential scores on all four factors (evaluative, activity, potency, and understandability) were highly correlated with comprehension of symbolic messages. These scores were unrelated to glance legibility of verbal messages, but two factors (evaluative and understandability) did correlate with glance legibility of symbolic messages. It was concluded that the semantic differential is a valid instrument for evaluating comprehension of symbolic sign messages and that it has advantages over other techniques.

scholarly journals Cannulation technique and complications in arteriovenous fistulas: a Swedish Renal Registry-based cohort study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Karin Staaf ◽  
Anders Fernström ◽  
Fredrik Uhlin
Keyword(s):  
Cohort Study ◽  
Lower Risk ◽  
Rate Ratio ◽  
Incidence Rate Ratio ◽  
National Registry ◽  
The Other ◽  
Arteriovenous Fistulas ◽  
Cannulation Technique ◽  
Using Data ◽  
The Relationship

Abstract Background The four cannulation techniques, rope ladder (RL), area puncture (AP), buttonhole with blunt needles (BHb), and buttonhole with sharp needles (BHs), affects the arteriovenous fistula (AVF) in different ways. The aim of this study was to describe the relationship between the different cannulation techniques and the occurrence of AVF complications. Methods The study was performed as a national registry-based cohort study using data from the Swedish Renal Registry (SRR). Data were collected from January 2014 to October 2019. Seventy of Sweden’s dialysis units participate in the registry. We analyzed a total of 1328 AVFs in this study. The risk of complications was compared between the four different cannulation techniques. The risk of AVF complications was measured by the incidence and incidence rate ratio (IRR). We compared the IRRs of complications between different cannulation techniques. Results BHs is the most common cannulation technique in Sweden. It has been used in 55% of the AVFs at some point during their functional patency. BHb (29%), RL (13%), and AP (3%) has been used less. BHb had the lowest risk of complications compared to the other techniques, and a significantly lower risk of stenosis, infiltration, cannulation difficulties, compared to RL and BHs. Cannulation difficulties were significantly more common using AP compared to BHs, and BHb. Infections were not significantly increased using the buttonhole technique. Conclusions BHb had the lowest risk of complications. Infections were not significantly increased using the buttonhole technique. Dialysis units with a low infection rate may continue to use the buttonhole technique, as the risk of complications is lower.

Do Migrants Think Differently? Evidence from Eastern European and Post-Soviet States

2018 ◽  
Vol 53 (3) ◽  
pp. 831-868 ◽  
Author(s):  
Ruxanda Berlinschi ◽  
Ani Harutyunyan
Keyword(s):  
Risk Aversion ◽  
International Migration ◽  
The Other ◽  
Eastern European ◽  
Risk Averse ◽  
Economic Liberalism ◽  
Self Selection ◽  
Using Data ◽  
Politically Active ◽  
Beliefs And Attitudes

This research investigates migrant self-selection on values, beliefs, and attitudes using data from Eastern European and former Soviet countries. We find that individuals who intend to emigrate are more politically active, more critical of governance and institutions, more tolerant toward other cultures, less tolerant of cheating, more optimistic, and less risk averse. With the exception of risk aversion, all selection patterns are heterogeneous across regions of origin. On the other hand, no self-selection pattern is detected on education, willingness to pay for public goods, and economic liberalism. These findings provide new insights into the determinants of international migration and reveal some of its less known consequences, such as a possible reduction of domestic pressure for political improvements in post-Soviet states due to politically active citizens’ higher propensity to emigrate.

The midpoint method: Magnetic interpretation of dikes and faults

Geophysics ◽  
1985 ◽  
Vol 50 (5) ◽  
pp. 834-839 ◽  
Author(s):  
I. V. Radhakrishna Murthy
Keyword(s):  
Characteristic Point ◽  
The Other ◽  
Magnetic Interpretation ◽  
Midpoint Method ◽  
Vertical Gradients

A method of magnetic interpretation of arbitrarily magnetized dikes and faults is developed, based on the properties of a new characteristic point called the “midpoint.” Anomaly profiles at two levels are considered, the maximum and minimum anomalies on them are located, and their midpoints are plotted. The rate of shift of the midpoint with elevation is a measure of the direction of magnetization. The distances between the points of maximum and minimum anomalies and the ratio of horizontal to vertical gradients in the case of faults are used to calculate the other parameters. I also suggest application of the method to anomalies of sheet‐like bodies.

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