Effect Of Uncertainty Research Articles

The impact of malaria on labour use and efficiency in the Sudan.

The paper seeks to examine the economic impact of malaria in the Sudan. Using longitudinal empirical data from a farming population in the Gezira, it examines and quantifies labour losses through malaria within families, observing simultaneously the manner in which altruism or "nafeer" helps families and communities insure their members against disease and other consequences of uncertainty.

Ab initio study of hydrogen bonding in the phenol–water system

AbstractThree hydrogen‐bonded minima on the phenol‐water, C6H5OH—H2O, potential energy surface were located with 3–21G and 6–31G** basis sets at both Hartree–Fock and MP2 levels of theory. MP2 binding energies were computed using large “correlation consistent” basis sets that included extra diffuse functions on all atoms. An estimate of the effect of expanding the basis set to the triple‐zeta level (multiple f functions on carbon and oxygen and multiple d functions on hydrogen) was derived from calculations on a related prototype system. The best estimates of the electronic binding energies for the three minima are –7.8, –5.0, and –2.0 kcal/mol. The consequences of uncertainties in the geometries and limitations in the level of correlation recovery are analyzed. It is suggested that our best estimates will likely underestimate the complete basis set, full CI values by 0.1–0.3 kcal/mol. Vibrational normal modes were determined for all three minima, including an MP2/6–31G** analysis for the most strongly bound complex. Computational strategies for larger phenol–water complexes are discussed. © John Wiley & Sons, Inc.

Extracting information on surface properties from bidirectional reflectance measurements

The retrieval of surface parameters from remotely sensed data is of prime interest for the estimation of surface properties of various planets in the solar system, including the Earth. Bidirectional reflectance measurements taken over natural surfaces in visible and near‐infrared spectral bands represent one data set from which these surface properties could be estimated. To achieve this goal, it is necessary to have both physical models predicting the bidirectional reflectance field as a function of the relevant surface parameters, and numerical procedures allowing the inversion of these models using a limited sampling of the bidirectional reflectance field. Given that theoretical models of the bidirectional reflectance have been published (Hapke, 1981, 1984, 1986; Verstraete et al., 1990) and that numerical procedures are available (Pinty et al., 1990), this paper focuses on the errors and uncertainties in the retrieved parameters which may arise because of (1) the weaknesses in our theoretical understanding and representation of the surface radiation transfer and (2) the errors in the bidirectional reflectance data. For instance, it is shown that the addition a posteriori of an amplitude parameter in the function accounting for the opposition effect can drastically modify the retrieved values of the optical and morphological parameters of the surface. The consequences of uncertainties in the reflectance data are also investigated, and the redistribution, by the inversion procedure, of such uncertainties on the retrieved parameters is discussed. Finally, synthetic reflectance data contaminated by a known random noise are used to examine the numerical stability of the retrieval and the compatibility between the models.

Election outcomes and the stockmarket

A macroeconomic model with sluggish labour markets and efficient financial markets is formulated. The consequences of uncertainty about election outcomes for share prices, interest rates, output and employment in the pre-election period are analysed. Also, the nature of the jumps in the stockmarket and the real economy on the morning after the election are analysed. This provides an alternative to the conventional theory of political business cycles and is able to explain large swings in the economy when election ‘news’ becomes known. It is shown that the stockmarket crashes (booms) when a Labour administration is elected into office with the promise that it will engage in a fiscal (monetary) expansion.

The FOMC in 1988: Uncertainty's Effects on Monetary Policy

The FOMC in 1988: Uncertainty's Effects on Monetary Policy

The Consequences of Uncertainty

The Consequences of Uncertainty

The consequences of uncertainty. An empirical approach to medical decision making in neonatal intensive care.

The policy of the Stanford University Medical Center on care for extremely premature neonates has been generally to initiate intensive care "based on a nonprobabilistic paradigm with a goal of saving every infant's life." Fischer and Stevenson analyzed the mortality rates, weights, gestational ages, and total costs of care for a sample of 68 low birth weight neonates. They also examined the outcomes of care in terms of degree of disability for the 24 surviving infants. They concluded that the existing policy resulted in undue suffering and in a substantial economic cost for the suffering and loss of life. They advocate use of an "individualized prognostic strategy" that takes into account the interplay of statistical prediction, the physician's assessment of clinical course, and parental responses when physicians suggest discontinuing aggressive care.

Estimating origin-destination matrices from roadside survey data

The purpose of this study is to develop a valid and efficient method for estimating origin-destination tables from roadside survey data. Roadside surveys, whether conducted by interviews or postcard mailback methods, typically have in common the sampling of trip origin and destination information at survey stations. These survey stations are generally located where roads cross “screenlines,” which are imaginary barriers drawn to intercept the trip types of interest.Such surveys also include counts of traffic volumes, by which the partial origin-destination (O-D) tables obtained at the different stations can be expanded and combined to obtain the complete O-D table which represents travel throughout the entire study area. The procedure used to expand the sample O-D information from the survey stations must recognize and deal appropriately with a number of problems: 1. (i) The “double counting” problem: Long-distance trips may pass through more than one survey station location; thus certain trips have the possibility of being sampled and expanded more than once, leading to a potentially serious overrepresentation of long-distance trips in the complete expanded trip table. 2. (ii) The “leaky screenline” problem: Some route choices, particularly those using very lightly traveled roads, may miss the survey stations entirely, leading to an underestimation of certain O-D patterns, or to distorted estimates if such sites are arbitrarily coupled with actual nearby station locations. 3. (iii) The efficient use of the data: There is a need to adjust expansion factors to compensate for double counting and leaky screenlines. How can this be accomplished such that all of the data obtained at the stations are used without loss of information? 4. (iv) The consequences of uncertainty and unknown travel behavior: Since the O-D data and other sampled variables are subject to random error, and since in general the probability of encountering a long-distance trip at some survey stations is affected by traveler route-choice behavior, which is not understood, the sample expansion procedure must rely on the use of erroneous input data and questionable assumptions. The preferred procedure must minimize, rather than amplify, the effects of such input errors. Here, five alternate methods for expanding roadside survey data in an unbiased manner are proposed and evaluated. In all cases, it is assumed that traveler route choice generally follows the pattern described by Dial's multipath assignment method. All methods are applied to a simple hypothetical network in order to examine their efficiency and error amplification properties. The evaluation of the five methods reveals that their performance properties vary considerably and that no single method is best in all circumstances. A microcomputer program has been provided as a tool to facilitate comparison among methods and to select the most appropriate expansion method for a particular application.

Uncertainty and variability in traffic signal calculations

The consequences of uncertainty and variability in data used for traffic signal calculations are investigated. A treatment of variable observations is devised and analysed. This shows that for small degrees of variability, use of mean values in conventional calculation methods will lead only to small losses in performance.

A canopy stomatal resistance model for gaseous deposition to vegetated surfaces

A gaseous deposition model, based on a realistic canopy stomatal resistance submodel, is described, analyzed and tested. This model is designed as one of a hierarchy of simulations, leading up to a “big-leaf” model of the processes contributing to the exchange of trace gases between the atmosphere and vegetated surfaces. Computations show that differences in plant species and environmental and physiological conditions can affect the canopy stomatal resistance by a factor of four. Canopy stomatal resistances to water vapor transfer computed with the present model are compared against values measured with a porometer and computed with the Penman-Monteith equation. Computed stomatal resistances from a soybean canopy in both well-watered and water-stressed conditions yield good agreement with test data. The stomatal resistance submodel responds well to changing environmental and physiological conditions. Model predictions of deposition velocities are evaluated for the case of ozone, transferred to maize. Calculated deposition velocities of O 3 overestimate measured values on the average by about 30%, probably largely as a consequence of uncertainties in leaf area index, soil and cuticle resistances, and other modeling parameters, but also partially due to imperfect measurement of O 3 deposition velocities.

Optimal feedback rules in an open economy macromodel with rational expectations

This paper outlines procedures for deriving optimal time-invariant linear feedback rules in continuous time linear stochastic models under rational expectations. It also examines the derivation of optimal simple rules of a similar type. These procedures are applied to an open economy model under rational expectations, and the consequences of uncertainty about stochastic disturbance structures for policy design are considered. The results indicate some preference for price level or nominal income rules rather than a monetary rule for the open economy.

Fitness, Uncertainty, and the Role of Diversification in Evolution and Behavior

I have shown how a maximum principle for evolutionary processes based solely upon mean fitness of behaviors may, under certain circumstances, be misrepresentative and misleading in the analysis of biological systems. Many of the misrepresentations can be corrected by including variance of fitness associated with environmental uncertainty and variability in the structure of the maximum principle. There are many ways of incorporating this variance into a mathematical model. I have chosen to depict the modified maximum principle as a discounted function of expected fitness, where the discount is a function of the variance in fitness between behaviors. Such a function under no uncertainty reverts to the simpler mean maxim. Including uncertainty generally results in evolutionary strategies consisting of sets of diverse behaviors whose resulting fitness show negative covariance. Under certainty organisms can specialize, showing only single types of behavior. Supporting evidence has been gathered from different areas of ecology and evolutionary biology. The model appears to be consistent with what I believe to be the consequences of uncertainty in sexual processes, herbivory and pollination systems. Future research will, hopefully, demonstrate the general applicability of this approach.

Some Effects of Parameter Variations on the Lateral-Directional Stability of Aircraft

Methods of analyzing the effects of aerodynamic uncertainties on the stability of lateral-directional motions are presented. Truncated and residualized reduced-order models of the motion are developed. Together with covariance analysis, these models provide simplified estimates of the probability of instability. A Space Shuttle entry flight condition is examined with this technique, and the predicted probability of open-loop instability is found to be low (< 0.0001). Monte Carlo stability analysis illustrates that closed-loop control can increase the probability of instability as a consequence of uncertainty in the control derivatives.

An alternative model for early Tertiary absolute plate motions

Research Article| August 01, 1978 An alternative model for early Tertiary absolute plate motions Donna M. Jurdy Donna M. Jurdy 1Department of Geological and Geophysical Sciences, Princeton University, Princeton, New Jersey 08540 Search for other works by this author on: GSW Google Scholar Author and Article Information Donna M. Jurdy 1Department of Geological and Geophysical Sciences, Princeton University, Princeton, New Jersey 08540 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1978) 6 (8): 469–472. https://doi.org/10.1130/0091-7613(1978)6<469:AAMFET>2.0.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Donna M. Jurdy; An alternative model for early Tertiary absolute plate motions. Geology 1978;; 6 (8): 469–472. doi: https://doi.org/10.1130/0091-7613(1978)6<469:AAMFET>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The absolute plate motions for early Tertiary time are reconsidered. The no-net-torque determination of Solomon and others indicated absolute plate motions at 55 m.y. ago that were considerably different from the present motions. To test whether these motions are truly characteristic of early Tertiary time or merely a consequence of uncertainties, an alternative model for the relative motions is considered. A single major change is made in the relative motions scheme: Antarctica is treated as two plates. The role of Antarctica is particularly important in the relative motion scheme because it is the sole link between the large Pacific Ocean plates and the other, largely continental plates. Although this relative plate motion model for early Tertiary time does not yield absolute motions that are compatible with those of the present, there are considerable differences from Solomon and others' determination. Thus, past relative plate motions must be further constrained to give absolute motions that can confidently be compared to the present set and used in testing hypotheses about driving forces. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Management of Breast Cancer: Radical Mastectomy

THE rejection of Dr. Crile's policies by most informed surgeons is not a consequence of uncertainty as to his precise meaning about local excision or It is rather a consequence of wide recognition of the extensive and easily demonstrable bias introduced by favorable case selection for the simple procedures that characterize his reports. This has been amply demonstrated in our article. There are, however, some points in Crile's article that merit further discussion and rebuttal. Crile asks, Is there increased risk in partial mastectomy? He answers the question by citing a retrospective, randomized, matched-pair study that as originally reported consisted of two groups of 53 patients: one group was treated by partial mastectomy and the other by total mastectomy. The ten-year survival rate for the partial mastectomy patients was a meager 34.4%. The data for the total mastectomy patients are not given, but it is stated that