Using Uncertainty Principle to Find the Ground-State Energy of the Helium and a Helium-like Hookean Atom

ERIC Educational Resources Information Center

Harbola, Varun

2011-01-01

In this paper, we accurately estimate the ground-state energy and the atomic radius of the helium atom and a helium-like Hookean atom by employing the uncertainty principle in conjunction with the variational approach. We show that with the use of the uncertainty principle, electrons are found to be spread over a radial region, giving an electron…

Comparison of Classical and Quantum Mechanical Uncertainties.

ERIC Educational Resources Information Center

Peslak, John, Jr.

1979-01-01

Comparisons are made for the particle-in-a-box, the harmonic oscillator, and the one-electron atom. A classical uncertainty principle is derived and compared with its quantum-mechanical counterpart. The results are discussed in terms of the statistical interpretation of the uncertainty principle. (Author/BB)

Self-completeness and the generalized uncertainty principle

NASA Astrophysics Data System (ADS)

Isi, Maximiliano; Mureika, Jonas; Nicolini, Piero

2014-03-01

The generalized uncertainty principle discloses a self-complete characteristic of gravity, namely the possibility of masking any curvature singularity behind an event horizon as a result of matter compression at the Planck scale. In this paper we extend the above reasoning in order to overcome some current limitations to the framework, including the absence of a consistent metric describing such Planck-scale black holes. We implement a minimum-size black hole in terms of the extremal configuration of a neutral non-rotating metric, which we derived by mimicking the effects of the generalized uncertainty principle via a short scale modified version of Einstein gravity. In such a way, we find a self- consistent scenario that reconciles the self-complete character of gravity and the generalized uncertainty principle.

Self-completeness and the generalized uncertainty principle

NASA Astrophysics Data System (ADS)

Isi, Maximiliano; Mureika, Jonas; Nicolini, Piero

2013-11-01

The generalized uncertainty principle discloses a self-complete characteristic of gravity, namely the possibility of masking any curvature singularity behind an event horizon as a result of matter compression at the Planck scale. In this paper we extend the above reasoning in order to overcome some current limitations to the framework, including the absence of a consistent metric describing such Planck-scale black holes. We implement a minimum-size black hole in terms of the extremal configuration of a neutral non-rotating metric, which we derived by mimicking the effects of the generalized uncertainty principle via a short scale modified version of Einstein gravity. In such a way, we find a self-consistent scenario that reconciles the self-complete character of gravity and the generalized uncertainty principle.

Uncertainty relations and topological-band insulator transitions in 2D gapped Dirac materials

NASA Astrophysics Data System (ADS)

Romera, E.; Calixto, M.

2015-05-01

Uncertainty relations are studied for a characterization of topological-band insulator transitions in 2D gapped Dirac materials isostructural with graphene. We show that the relative or Kullback-Leibler entropy in position and momentum spaces, and the standard variance-based uncertainty relation give sharp signatures of topological phase transitions in these systems.

A method to estimate the additional uncertainty in gap-filled NEE resulting from long gaps in the CO2 flux record

Treesearch

Andrew D. Richardson; David Y. Hollinger

2007-01-01

Missing values in any data set create problems for researchers. The process by which missing values are replaced, and the data set is made complete, is generally referred to as imputation. Within the eddy flux community, the term "gap filling" is more commonly applied. A major challenge is that random errors in measured data result in uncertainty in the gap-...

Integrating info-gap decision theory with robust population management: a case study using the Mountain Plover.

PubMed

van der Burg, Max Post; Tyre, Andrew J

2011-01-01

Wildlife managers often make decisions under considerable uncertainty. In the most extreme case, a complete lack of data leads to uncertainty that is unquantifiable. Information-gap decision theory deals with assessing management decisions under extreme uncertainty, but it is not widely used in wildlife management. So too, robust population management methods were developed to deal with uncertainties in multiple-model parameters. However, the two methods have not, as yet, been used in tandem to assess population management decisions. We provide a novel combination of the robust population management approach for matrix models with the information-gap decision theory framework for making conservation decisions under extreme uncertainty. We applied our model to the problem of nest survival management in an endangered bird species, the Mountain Plover (Charadrius montanus). Our results showed that matrix sensitivities suggest that nest management is unlikely to have a strong effect on population growth rate, confirming previous analyses. However, given the amount of uncertainty about adult and juvenile survival, our analysis suggested that maximizing nest marking effort was a more robust decision to maintain a stable population. Focusing on the twin concepts of opportunity and robustness in an information-gap model provides a useful method of assessing conservation decisions under extreme uncertainty.

Quantum corrections to newtonian potential and generalized uncertainty principle

NASA Astrophysics Data System (ADS)

Scardigli, Fabio; Lambiase, Gaetano; Vagenas, Elias

2017-08-01

We use the leading quantum corrections to the newtonian potential to compute the deformation parameter of the generalized uncertainty principle. By assuming just only General Relativity as theory of Gravitation, and the thermal nature of the GUP corrections to the Hawking spectrum, our calculation gives, to first order, a specific numerical result. We briefly discuss the physical meaning of this value, and compare it with the previously obtained bounds on the generalized uncertainty principle deformation parameter.

Uncertainty principle in loop quantum cosmology by Moyal formalism

NASA Astrophysics Data System (ADS)

Perlov, Leonid

2018-03-01

In this paper, we derive the uncertainty principle for the loop quantum cosmology homogeneous and isotropic Friedmann-Lemaiter-Robertson-Walker model with the holonomy-flux algebra. The uncertainty principle is between the variables c, with the meaning of connection and μ having the meaning of the physical cell volume to the power 2/3, i.e., v2 /3 or a plaquette area. Since both μ and c are not operators, but rather the random variables, the Robertson uncertainty principle derivation that works for hermitian operators cannot be used. Instead we use the Wigner-Moyal-Groenewold phase space formalism. The Wigner-Moyal-Groenewold formalism was originally applied to the Heisenberg algebra of the quantum mechanics. One can derive it from both the canonical and path integral quantum mechanics as well as the uncertainty principle. In this paper, we apply it to the holonomy-flux algebra in the case of the homogeneous and isotropic space. Another result is the expression for the Wigner function on the space of the cylindrical wave functions defined on Rb in c variables rather than in dual space μ variables.

An uncertainty principle for unimodular quantum groups

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crann, Jason; Université Lille 1 - Sciences et Technologies, UFR de Mathématiques, Laboratoire de Mathématiques Paul Painlevé - UMR CNRS 8524, 59655 Villeneuve d'Ascq Cédex; Kalantar, Mehrdad, E-mail: jason-crann@carleton.ca, E-mail: mkalanta@math.carleton.ca

2014-08-15

We present a generalization of Hirschman's entropic uncertainty principle for locally compact Abelian groups to unimodular locally compact quantum groups. As a corollary, we strengthen a well-known uncertainty principle for compact groups, and generalize the relation to compact quantum groups of Kac type. We also establish the complementarity of finite-dimensional quantum group algebras. In the non-unimodular setting, we obtain an uncertainty relation for arbitrary locally compact groups using the relative entropy with respect to the Haar weight as the measure of uncertainty. We also show that when restricted to q-traces of discrete quantum groups, the relative entropy with respect tomore » the Haar weight reduces to the canonical entropy of the random walk generated by the state.« less

Constraining the generalized uncertainty principle with the atomic weak-equivalence-principle test

NASA Astrophysics Data System (ADS)

Gao, Dongfeng; Wang, Jin; Zhan, Mingsheng

2017-04-01

Various models of quantum gravity imply the Planck-scale modifications of Heisenberg's uncertainty principle into a so-called generalized uncertainty principle (GUP). The GUP effects on high-energy physics, cosmology, and astrophysics have been extensively studied. Here, we focus on the weak-equivalence-principle (WEP) violation induced by the GUP. Results from the WEP test with the 85Rb-87Rb dual-species atom interferometer are used to set upper bounds on parameters in two GUP proposals. A 1045-level bound on the Kempf-Mangano-Mann proposal and a 1027-level bound on Maggiore's proposal, which are consistent with bounds from other experiments, are obtained. All these bounds have huge room for improvement in the future.

Decision Making Under Uncertainty - Bridging the Gap Between End User Needs and Science Capability

NASA Astrophysics Data System (ADS)

Verdon-Kidd, D. C.; Kiem, A.; Austin, E. K.

2012-12-01

Successful adaptation outcomes depend on decision making based on the best available climate science information. However, a fundamental barrier exists, namely the 'gap' between information that climate science can currently provide and the information that is practically useful for end users and decision makers. This study identifies the major contributing factors to the 'gap' from an Australian perspective and provides recommendations as to ways in which the 'gap' may be narrowed. This was achieved via a literature review, online survey (targeted to providers of climate information and end users of that information), workshop (where both climate scientists and end users came together to discuss key issues) and focus group. The study confirmed that uncertainty in climate science is a key barrier to adaptation. The issue of uncertainty was found to be multi-faceted, with issues identified in terms of communication of uncertainty, misunderstanding of uncertainty and the lack of tools/methods to deal with uncertainty. There were also key differences in terms of expectations for the future - most end users were of the belief that uncertainty associated with future climate projections would reduce within the next five to 10 years, however producers of climate science information were well aware that this would most likely not be the case. This is a concerning finding as end users may delay taking action on adaptation and risk planning until the uncertainties are reduced - a situation which may never eventuate or may occur after the optimal time for action. Improved communication and packaging of climate information was another key theme that was highlighted in this study. Importantly, it was made clear that improved communication is not just about more glossy brochures and presentations by climate scientists, rather there is a role for a program or group to fill this role (coined a 'knowledge broker' during the workshop and focus group). The role of the 'knowledge broker' would be to package, translate (both from end user to scientist and scientist to end user) and transform climate information. Importantly communication of uncertainty needs to be improved so that end users are aware of all the caveats and what can realistically be expected from climate science now and in the near future. Overall this study confirmed that there is indeed a 'gap' between end user's needs and science capability, particularly with respect to uncertainty, communication and packaging of climate information. This 'gap' has been a barrier to successful climate change adaptation in the past. While it is unrealistic to think we could ever close the 'gap' completely, based on the recommendations provided in this paper, it may be possible to bridge the 'gap' (or at least improve people's awareness of the 'gap'). Furthermore, the insights gained and recommendations provided from this study, while based on an Australian context, are likely to be applicable to many other regions of the world, grappling with similar issues.

Research on the effects of geometrical and material uncertainties on the band gap of the undulated beam

NASA Astrophysics Data System (ADS)

Li, Yi; Xu, Yanlong

2017-09-01

Considering uncertain geometrical and material parameters, the lower and upper bounds of the band gap of an undulated beam with periodically arched shape are studied by the Monte Carlo Simulation (MCS) and interval analysis based on the Taylor series. Given the random variations of the overall uncertain variables, scatter plots from the MCS are used to analyze the qualitative sensitivities of the band gap respect to these uncertainties. We find that the influence of uncertainty of the geometrical parameter on the band gap of the undulated beam is stronger than that of the material parameter. And this conclusion is also proved by the interval analysis based on the Taylor series. Our methodology can give a strategy to reduce the errors between the design and practical values of the band gaps by improving the accuracy of the specially selected uncertain design variables of the periodical structures.

[Theoretical risk management and legitimacy of the precautionary principle in medicine. Look back at HIV contamination through blood transfusion in France, twenty years ago].

PubMed

Moutel, G; Hergon, E; Duchange, N; Bellier, L; Rouger, P; Hervé, C

2005-02-01

The precautionary principle first appeared in France during the health crisis following the contamination of patients with HIV via blood transfusion. This study analyses whether the risk associated with blood transfusion was taken into account early enough considering the context of scientific uncertainty between 1982 and 1985. The aim was to evaluate whether a precautionary principle was applied and whether it was relevant. First, we investigated the context of scientific uncertainty and controversies prevailing between 1982 and 1985. Then we analysed the attitude and decisions of the French authorities in this situation to determine whether a principle of precaution was applied. Finally, we explored the reasons at the origin of the delay in controlling the risk. Despite the scientific uncertainties associated with the potential risk of HIV contamination by transfusion in 1983, we found that a list of recommendations aiming to reduce this risk was published in June of that year. In the prevailing climate of uncertainty, these measures could be seen as precautionary. However, the recommended measures were not widely applied. Cultural, structural and economic factors hindered their implementation. Our analysis provides insight into the use of precautionary principle in the domain of blood transfusion and, more generally, medicine. It also sheds light on the expectations that health professionals should have of this principle. The aim of the precautionary principle is to manage rather than to reduce scientific uncertainty. The principle is not a futile search for zero risk. Rather, it is a principle for action allowing precautionary measures to be taken. However, we show that these measures must appear legitimate to be applied. This legitimacy requires an adapted decision-making process, involving all those concerned in the management of collective risks.

Uncertainty principles for inverse source problems for electromagnetic and elastic waves

NASA Astrophysics Data System (ADS)

Griesmaier, Roland; Sylvester, John

2018-06-01

In isotropic homogeneous media, far fields of time-harmonic electromagnetic waves radiated by compactly supported volume currents, and elastic waves radiated by compactly supported body force densities can be modelled in very similar fashions. Both are projected restricted Fourier transforms of vector-valued source terms. In this work we generalize two types of uncertainty principles recently developed for far fields of scalar-valued time-harmonic waves in Griesmaier and Sylvester (2017 SIAM J. Appl. Math. 77 154–80) to this vector-valued setting. These uncertainty principles yield stability criteria and algorithms for splitting far fields radiated by collections of well-separated sources into the far fields radiated by individual source components, and for the restoration of missing data segments. We discuss proper regularization strategies for these inverse problems, provide stability estimates based on the new uncertainty principles, and comment on reconstruction schemes. A numerical example illustrates our theoretical findings.

Climate change adaptation under uncertainty in the developing world: A case study of sea level rise in Kiribati

NASA Astrophysics Data System (ADS)

Donner, S. D.; Webber, S.

2011-12-01

Climate change is expected to have the greatest impact in parts of the developing world. At the 2010 meeting of U.N. Framework Convention on Climate Change in Cancun, industrialized countries agreed in principle to provide US$100 billion per year by 2020 to assist the developing world respond to climate change. This "Green Climate Fund" is a critical step towards addressing the challenge of climate change. However, the policy and discourse on supporting adaptation in the developing world remains highly idealized. For example, the efficacy of "no regrets" adaptation efforts or "mainstreaming" adaptation into decision-making are rarely evaluated in the real world. In this presentation, I will discuss the gap between adaptation theory and practice using a multi-year case study of the cultural, social and scientific obstacles to adapting to sea level rise in the Pacific atoll nation of Kiribati. Our field research reveals how scientific and institutional uncertainty can limit international efforts to fund adaptation and lead to spiraling costs. Scientific uncertainty about hyper-local impacts of sea level rise, though irreducible, can at times limit decision-making about adaptation measures, contrary to the notion that "good" decision-making practices can incorporate scientific uncertainty. Efforts to improve institutional capacity must be done carefully, or they risk inadvertently slowing the implementation of adaptation measures and increasing the likelihood of "mal"-adaptation.

Single-Slit Diffraction and the Uncertainty Principle

ERIC Educational Resources Information Center

Rioux, Frank

2005-01-01

A theoretical analysis of single-slit diffraction based on the Fourier transform between coordinate and momentum space is presented. The transform between position and momentum is used to illuminate the intimate relationship between single-slit diffraction and uncertainty principle.

The `Heisenberg's Microscope' as an Example of Using Thought Experiments in Teaching Physics Theories to Students of the Upper Secondary School

NASA Astrophysics Data System (ADS)

Velentzas, Athanasios; Halkia, Krystallia

2011-08-01

In this work an attempt is made to explore the possible value of using Thought Experiments (TEs) in teaching physics to upper secondary education students. Specifically, a qualitative research project is designed to investigate the extent to which the Thought Experiment (TE) called `Heisenberg's Microscope', as it has been transformed by Gamow for the public in his book Mr. Tompkins in Paperback, can function as a tool in the teaching of the `uncertainty principle'. The sample in the research consisted of 40 Greek students, in 11 groups of 3-4 students each. The findings of this study reveal that the use of this TE has positive results in teaching the uncertainty principle. Students, based on the TE, were able (i) to derive a formula of the uncertainty principle, (ii) to explain that the uncertainty principle is a general principle in nature and it is not a result of incompleteness of the experimental devices and (iii) to argue that it is impossible to determine the trajectory of a particle as a mathematical line.

The action uncertainty principle and quantum gravity

NASA Astrophysics Data System (ADS)

Mensky, Michael B.

1992-02-01

Results of the path-integral approach to the quantum theory of continuous measurements have been formulated in a preceding paper in the form of an inequality of the type of the uncertainty principle. The new inequality was called the action uncertainty principle, AUP. It was shown that the AUP allows one to find in a simple what outputs of the continuous measurements will occur with high probability. Here a more simple form of the AUP will be formulated, δ S≳ħ. When applied to quantum gravity, it leads in a very simple way to the Rosenfeld inequality for measurability of the average curvature.

An uncertainty budget for VHF and UHF reflectometers

NASA Astrophysics Data System (ADS)

Ridler, N. M.; Medley, C. J.

1992-05-01

Details of the derivation of an uncertainty budget for one port immittance or complex voltage reflection coefficient measuring instruments, operating at VHF and UHF in the 14 mm 50 ohm coaxial line size, are reported. The principles of the uncertainty budget are given along with experimental results obtained using six ports and a network analyzer as the measuring instruments. Details of the types of calibration for which the uncertainty budget is suitable are reported. Various aspects of the uncertainty budget are considered and general principles and treatment of the type A and type B contributions are discussed. Experimental results obtained using the uncertainty budget are given. A summary of uncertainties for the six ports and HP8753B automatic network analyzer are also given.

A Hierarchical Multi-Model Approach for Uncertainty Segregation, Prioritization and Comparative Evaluation of Competing Modeling Propositions

NASA Astrophysics Data System (ADS)

Tsai, F. T.; Elshall, A. S.; Hanor, J. S.

2012-12-01

Subsurface modeling is challenging because of many possible competing propositions for each uncertain model component. How can we judge that we are selecting the correct proposition for an uncertain model component out of numerous competing propositions? How can we bridge the gap between synthetic mental principles such as mathematical expressions on one hand, and empirical observation such as observation data on the other hand when uncertainty exists on both sides? In this study, we introduce hierarchical Bayesian model averaging (HBMA) as a multi-model (multi-proposition) framework to represent our current state of knowledge and decision for hydrogeological structure modeling. The HBMA framework allows for segregating and prioritizing different sources of uncertainty, and for comparative evaluation of competing propositions for each source of uncertainty. We applied the HBMA to a study of hydrostratigraphy and uncertainty propagation of the Southern Hills aquifer system in the Baton Rouge area, Louisiana. We used geophysical data for hydrogeological structure construction through indictor hydrostratigraphy method and used lithologic data from drillers' logs for model structure calibration. However, due to uncertainty in model data, structure and parameters, multiple possible hydrostratigraphic models were produced and calibrated. The study considered four sources of uncertainties. To evaluate mathematical structure uncertainty, the study considered three different variogram models and two geological stationarity assumptions. With respect to geological structure uncertainty, the study considered two geological structures with respect to the Denham Springs-Scotlandville fault. With respect to data uncertainty, the study considered two calibration data sets. These four sources of uncertainty with their corresponding competing modeling propositions resulted in 24 calibrated models. The results showed that by segregating different sources of uncertainty, HBMA analysis provided insights on uncertainty priorities and propagation. In addition, it assisted in evaluating the relative importance of competing modeling propositions for each uncertain model component. By being able to dissect the uncertain model components and provide weighted representation of the competing propositions for each uncertain model component based on the background knowledge, the HBMA functions as an epistemic framework for advancing knowledge about the system under study.

Robustness of risk maps and survey networks to knowledge gaps about a new invasive pest.

PubMed

Yemshanov, Denys; Koch, Frank H; Ben-Haim, Yakov; Smith, William D

2010-02-01

In pest risk assessment it is frequently necessary to make management decisions regarding emerging threats under severe uncertainty. Although risk maps provide useful decision support for invasive alien species, they rarely address knowledge gaps associated with the underlying risk model or how they may change the risk estimates. Failure to recognize uncertainty leads to risk-ignorant decisions and miscalculation of expected impacts as well as the costs required to minimize these impacts. Here we use the information gap concept to evaluate the robustness of risk maps to uncertainties in key assumptions about an invading organism. We generate risk maps with a spatial model of invasion that simulates potential entries of an invasive pest via international marine shipments, their spread through a landscape, and establishment on a susceptible host. In particular, we focus on the question of how much uncertainty in risk model assumptions can be tolerated before the risk map loses its value. We outline this approach with an example of a forest pest recently detected in North America, Sirex noctilio Fabricius. The results provide a spatial representation of the robustness of predictions of S. noctilio invasion risk to uncertainty and show major geographic hotspots where the consideration of uncertainty in model parameters may change management decisions about a new invasive pest. We then illustrate how the dependency between the extent of uncertainties and the degree of robustness of a risk map can be used to select a surveillance network design that is most robust to knowledge gaps about the pest.

Polar Wavelet Transform and the Associated Uncertainty Principles

NASA Astrophysics Data System (ADS)

Shah, Firdous A.; Tantary, Azhar Y.

2018-06-01

The polar wavelet transform- a generalized form of the classical wavelet transform has been extensively used in science and engineering for finding directional representations of signals in higher dimensions. The aim of this paper is to establish new uncertainty principles associated with the polar wavelet transforms in L2(R2). Firstly, we study some basic properties of the polar wavelet transform and then derive the associated generalized version of Heisenberg-Pauli-Weyl inequality. Finally, following the idea of Beckner (Proc. Amer. Math. Soc. 123, 1897-1905 1995), we drive the logarithmic version of uncertainty principle for the polar wavelet transforms in L2(R2).

Time-Frequency Representations for Speech Signals.

DTIC Science & Technology

1987-06-01

and subsequent processing can take these weights into account . This is, in principle , safer, but pratically it is much harder to think about processing...and frequency along the other. But how should this idea be made precise (the well-known uncertainty principle of fourier analysis is one of the thorny...produce similar results. q2.3. Non-stationarity 19 it is the unique shape that meets the uncertainty principle with equality. 2.2. The quasi-stationary

The Uncertainty Principle, Virtual Particles and Real Forces

ERIC Educational Resources Information Center

Jones, Goronwy Tudor

2002-01-01

This article provides a simple practical introduction to wave-particle duality, including the energy-time version of the Heisenberg Uncertainty Principle. It has been successful in leading students to an intuitive appreciation of "virtual particles" and the role they play in describing the way ordinary particles, like electrons and protons, exert…

Risk assessment principle for engineered nanotechnology in food and drug.

PubMed

Hwang, Myungsil; Lee, Eun Ji; Kweon, Se Young; Park, Mi Sun; Jeong, Ji Yoon; Um, Jun Ho; Kim, Sun Ah; Han, Bum Suk; Lee, Kwang Ho; Yoon, Hae Jung

2012-06-01

While the ability to develop nanomaterials and incorporate them into products is advancing rapidly worldwide, understanding of the potential health safety effects of nanomaterials has proceeded at a much slower pace. Since 2008, Korea Food and Drug Administration (KFDA) started an investigation to prepare "Strategic Action Plan" to evaluate safety and nano risk management associated with foods, drugs, medical devices and cosmetics using nano-scale materials. Although there are some studies related to potential risk of nanomaterials, physical-chemical characterization of nanomaterials is not clear yet and these do not offer enough information due to their limitations. Their uncertainties make it impossible to determine whether nanomaterials are actually hazardous to human. According to the above mention, we have some problems to conduct the human exposure risk assessment currently. On the other hand, uncertainty about safety may lead to polarized public debate and to businesses unwillingness for further nanotechnology investigation. Therefore, the criteria and methods to assess possible adverse effects of nanomaterials have been vigorously taken into consideration by many international organizations: the World Health Organization, the Organization for Economic and Commercial Development and the European Commission. The object of this study was to develop risk assessment principles for safety management of future nanoproducts and also to identify areas of research to strengthen risk assessment for nanomaterials. The research roadmaps which were proposed in this study will be helpful to fill up the current gaps in knowledge relevant nano risk assessment.

Setting the most robust effluent level under severe uncertainty: application of information-gap decision theory to chemical management.

PubMed

Yokomizo, Hiroyuki; Naito, Wataru; Tanaka, Yoshinari; Kamo, Masashi

2013-11-01

Decisions in ecological risk management for chemical substances must be made based on incomplete information due to uncertainties. To protect the ecosystems from the adverse effect of chemicals, a precautionary approach is often taken. The precautionary approach, which is based on conservative assumptions about the risks of chemical substances, can be applied selecting management models and data. This approach can lead to an adequate margin of safety for ecosystems by reducing exposure to harmful substances, either by reducing the use of target chemicals or putting in place strict water quality criteria. However, the reduction of chemical use or effluent concentrations typically entails a financial burden. The cost effectiveness of the precautionary approach may be small. Hence, we need to develop a formulaic methodology in chemical risk management that can sufficiently protect ecosystems in a cost-effective way, even when we do not have sufficient information for chemical management. Information-gap decision theory can provide the formulaic methodology. Information-gap decision theory determines which action is the most robust to uncertainty by guaranteeing an acceptable outcome under the largest degree of uncertainty without requiring information about the extent of parameter uncertainty at the outset. In this paper, we illustrate the application of information-gap decision theory to derive a framework for setting effluent limits of pollutants for point sources under uncertainty. Our application incorporates a cost for reduction in pollutant emission and a cost to wildlife species affected by the pollutant. Our framework enables us to settle upon actions to deal with severe uncertainty in ecological risk management of chemicals. Copyright © 2013 Elsevier Ltd. All rights reserved.

Robustness of risk maps and survey networks to knowledge gaps about a new invasive pest

Treesearch

Denys Yemshanov; Frank H. Koch; Yakov Ben-Haim; William D. Smith

2010-01-01

In pest risk assessment it is frequently necessary to make management decisions regarding emerging threats under severe uncertainty. Although risk maps provide useful decision support for invasive alien species, they rarely address knowledge gaps associated with the underlying risk model or how they may change the risk estimates. Failure to recognize uncertainty leads...

Squeezed States, Uncertainty Relations and the Pauli Principle in Composite and Cosmological Models

NASA Technical Reports Server (NTRS)

Terazawa, Hidezumi

1996-01-01

The importance of not only uncertainty relations but also the Pauli exclusion principle is emphasized in discussing various 'squeezed states' existing in the universe. The contents of this paper include: (1) Introduction; (2) Nuclear Physics in the Quark-Shell Model; (3) Hadron Physics in the Standard Quark-Gluon Model; (4) Quark-Lepton-Gauge-Boson Physics in Composite Models; (5) Astrophysics and Space-Time Physics in Cosmological Models; and (6) Conclusion. Also, not only the possible breakdown of (or deviation from) uncertainty relations but also the superficial violation of the Pauli principle at short distances (or high energies) in composite (and string) models is discussed in some detail.

Assembling GHERG: Could "academic crowd-sourcing" address gaps in global health estimates?

PubMed

Rudan, Igor; Campbell, Harry; Marušić, Ana; Sridhar, Devi; Nair, Harish; Adeloye, Davies; Theodoratou, Evropi; Chan, Kit Yee

2015-06-01

In recent months, the World Health Organization (WHO), independent academic researchers, the Lancet and PLoS Medicine journals worked together to improve reporting of population health estimates. The new guidelines for accurate and transparent health estimates reporting (likely to be named GATHER), which are eagerly awaited, represent a helpful move that should benefit the field of global health metrics. Building on this progress and drawing from a tradition of Child Health Epidemiology Reference Group (CHERG)'s successful work model, we would like to propose a new initiative - "Global Health Epidemiology Reference Group" (GHERG). We see GHERG as an informal and entirely voluntary international collaboration of academic groups who are willing to contribute to improving disease burden estimates and respect the principles of the new guidelines - a form of "academic crowd-sourcing". The main focus of GHERG will be to identify the "gap areas" where not much information is available and/or where there is a lot of uncertainty present about the accuracy of the existing estimates. This approach should serve to complement the existing WHO and IHME estimates and to represent added value to both efforts.

Two new kinds of uncertainty relations

NASA Technical Reports Server (NTRS)

Uffink, Jos

1994-01-01

We review a statistical-geometrical and a generalized entropic approach to the uncertainty principle. Both approaches provide a strengthening and generalization of the standard Heisenberg uncertainty relations, but in different directions.

Generalized uncertainty principle: implications for black hole complementarity

NASA Astrophysics Data System (ADS)

Chen, Pisin; Ong, Yen Chin; Yeom, Dong-han

2014-12-01

At the heart of the black hole information loss paradox and the firewall controversy lies the conflict between quantum mechanics and general relativity. Much has been said about quantum corrections to general relativity, but much less in the opposite direction. It is therefore crucial to examine possible corrections to quantum mechanics due to gravity. Indeed, the Heisenberg Uncertainty Principle is one profound feature of quantum mechanics, which nevertheless may receive correction when gravitational effects become important. Such generalized uncertainty principle [GUP] has been motivated from not only quite general considerations of quantum mechanics and gravity, but also string theoretic arguments. We examine the role of GUP in the context of black hole complementarity. We find that while complementarity can be violated by large N rescaling if one assumes only the Heisenberg's Uncertainty Principle, the application of GUP may save complementarity, but only if certain N -dependence is also assumed. This raises two important questions beyond the scope of this work, i.e., whether GUP really has the proposed form of N -dependence, and whether black hole complementarity is indeed correct.

Orbiter Gap Filler Bending Model for Re-entry

NASA Technical Reports Server (NTRS)

Campbell, Charles H.

2007-01-01

Pressure loads on a protruding gap filler during an Orbiter reentry are investigated to evaluate the likelihood of extraction due to pressure loads, and to ascertain how much bending will be induced by re-entry pressure loads. Oblique shock wave theory is utilized to develop a representation of the pressure loads induced on a gap filler for the ISSHVFW trajectory, representative of a heavy weight ISS return. A free body diagram is utilized to react the forces induced by the pressure forces. Preliminary results developed using these methods demonstrate that pressure loads, alone, are not likely causes of gap filler extraction during reentry. Assessment of the amount a gap filler will bend over is presented. Implications of gap filler bending during re-entry include possible mitigation of early boundary layer transition concerns, uncertainty in ground based measurement of protruding gap fillers from historical Orbiter flight history, and uncertainty in the use of Orbiter gap fillers for boundary layer prediction calibration. Authors will be added to the author list as appropriate.

“Stringy” coherent states inspired by generalized uncertainty principle

NASA Astrophysics Data System (ADS)

Ghosh, Subir; Roy, Pinaki

2012-05-01

Coherent States with Fractional Revival property, that explicitly satisfy the Generalized Uncertainty Principle (GUP), have been constructed in the context of Generalized Harmonic Oscillator. The existence of such states is essential in motivating the GUP based phenomenological results present in the literature which otherwise would be of purely academic interest. The effective phase space is Non-Canonical (or Non-Commutative in popular terminology). Our results have a smooth commutative limit, equivalent to Heisenberg Uncertainty Principle. The Fractional Revival time analysis yields an independent bound on the GUP parameter. Using this and similar bounds obtained here, we derive the largest possible value of the (GUP induced) minimum length scale. Mandel parameter analysis shows that the statistics is Sub-Poissonian. Correspondence Principle is deformed in an interesting way. Our computational scheme is very simple as it requires only first order corrected energy values and undeformed basis states.

The Generalized Uncertainty Principle and Harmonic Interaction in Three Spatial Dimensions

NASA Astrophysics Data System (ADS)

Hassanabadi, H.; Hooshmand, P.; Zarrinkamar, S.

2015-01-01

In three spatial dimensions, the generalized uncertainty principle is considered under an isotropic harmonic oscillator interaction in both non-relativistic and relativistic regions. By using novel transformations and separations of variables, the exact analytical solution of energy eigenvalues as well as the wave functions is obtained. Time evolution of the non-relativistic region is also reported.

Making Invasion models useful for decision makers; incorporating uncertainty, knowledge gaps, and decision-making preferences

Treesearch

Denys Yemshanov; Frank H Koch; Mark Ducey

2015-01-01

Uncertainty is inherent in model-based forecasts of ecological invasions. In this chapter, we explore how the perceptions of that uncertainty can be incorporated into the pest risk assessment process. Uncertainty changes a decision maker’s perceptions of risk; therefore, the direct incorporation of uncertainty may provide a more appropriate depiction of risk. Our...

Wave-Particle Duality and Uncertainty Principle: Phenomenographic Categories of Description of Tertiary Physics Students' Depictions

ERIC Educational Resources Information Center

Ayene, Mengesha; Kriek, Jeanne; Damtie, Baylie

2011-01-01

Quantum mechanics is often thought to be a difficult subject to understand, not only in the complexity of its mathematics but also in its conceptual foundation. In this paper we emphasize students' depictions of the uncertainty principle and wave-particle duality of quantum events, phenomena that could serve as a foundation in building an…

Risk management frameworks: supporting the next generation of Murray-Darling Basin water sharing plans

NASA Astrophysics Data System (ADS)

Podger, G. M.; Cuddy, S. M.; Peeters, L.; Smith, T.; Bark, R. H.; Black, D. C.; Wallbrink, P.

2014-09-01

Water jurisdictions in Australia are required to prepare and implement water resource plans. In developing these plans the common goal is realising the best possible use of the water resources - maximising outcomes while minimising negative impacts. This requires managing the risks associated with assessing and balancing cultural, industrial, agricultural, social and environmental demands for water within a competitive and resource-limited environment. Recognising this, conformance to international risk management principles (ISO 31000:2009) have been embedded within the Murray-Darling Basin Plan. Yet, to date, there has been little strategic investment by water jurisdictions in bridging the gap between principle and practice. The ISO 31000 principles and the risk management framework that embodies them align well with an adaptive management paradigm within which to conduct water resource planning. They also provide an integrative framework for the development of workflows that link risk analysis with risk evaluation and mitigation (adaptation) scenarios, providing a transparent, repeatable and robust platform. This study, through a demonstration use case and a series of workflows, demonstrates to policy makers how these principles can be used to support the development of the next generation of water sharing plans in 2019. The workflows consider the uncertainty associated with climate and flow inputs, and model parameters on irrigation and hydropower production, meeting environmental flow objectives and recreational use of the water resource. The results provide insights to the risks associated with meeting a range of different objectives.

Methods for Estimating the Uncertainty in Emergy Table-Form Models

EPA Science Inventory

Emergy studies have suffered criticism due to the lack of uncertainty analysis and this shortcoming may have directly hindered the wider application and acceptance of this methodology. Recently, to fill this gap, the sources of uncertainty in emergy analysis were described and an...

A review of the generalized uncertainty principle.

PubMed

Tawfik, Abdel Nasser; Diab, Abdel Magied

2015-12-01

Based on string theory, black hole physics, doubly special relativity and some 'thought' experiments, minimal distance and/or maximum momentum are proposed. As alternatives to the generalized uncertainty principle (GUP), the modified dispersion relation, the space noncommutativity, the Lorentz invariance violation, and the quantum-gravity-induced birefringence effects are summarized. The origin of minimal measurable quantities and the different GUP approaches are reviewed and the corresponding observations are analysed. Bounds on the GUP parameter are discussed and implemented in the understanding of recent PLANCK observations of cosmic inflation. The higher-order GUP approaches predict minimal length uncertainty with and without maximum momenta. Possible arguments against the GUP are discussed; for instance, the concern about its compatibility with the equivalence principles, the universality of gravitational redshift and the free fall and law of reciprocal action are addressed.

The precautionary principle within European Union public health policy. The implementation of the principle under conditions of supranationality and citizenship.

PubMed

Antonopoulou, Lila; van Meurs, Philip

2003-11-01

The present study examines the precautionary principle within the parameters of public health policy in the European Union, regarding both its meaning, as it has been shaped by relevant EU institutions and their counterparts within the Member States, and its implementation in practice. In the initial section I concentrate on the methodological question of "scientific uncertainty" concerning the calculation of risk and possible damage. Calculation of risk in many cases justifies the adopting of preventive measures, but, as it is argued, the principle of precaution and its implementation cannot be wholly captured by a logic of calculation; such a principle does not only contain scientific uncertainty-as the preventive principle does-but it itself is generated as a principle by this scientific uncertainty, recognising the need for a society to act. Thus, the implementation of the precautionary principle is also a simultaneous search for justification of its status as a principle. This justification would result in the adoption of precautionary measures against risk although no proof of this principle has been produced based on the "cause-effect" model. The main part of the study is occupied with an examination of three cases from which the stance of the official bodies of the European Union towards the precautionary principle and its implementation emerges: the case of the "mad cows" disease, the case of production and commercialization of genetically modified foodstuffs. The study concludes with the assessment that the effective implementation of the precautionary principle on a European level depends on the emergence of a concerned Europe-wide citizenship and its acting as a mechanism to counteract the material and social conditions that pose risks for human health.

Sensitivity-Uncertainty Techniques for Nuclear Criticality Safety

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Forrest B.; Rising, Michael Evan; Alwin, Jennifer Louise

2017-08-07

The sensitivity and uncertainty analysis course will introduce students to k eff sensitivity data, cross-section uncertainty data, how k eff sensitivity data and k eff uncertainty data are generated and how they can be used. Discussion will include how sensitivity/uncertainty data can be used to select applicable critical experiments, to quantify a defensible margin to cover validation gaps and weaknesses, and in development of upper subcritical limits.

Uncertainty relations with the generalized Wigner-Yanase-Dyson skew information

NASA Astrophysics Data System (ADS)

Fan, Yajing; Cao, Huaixin; Wang, Wenhua; Meng, Huixian; Chen, Liang

2018-07-01

The uncertainty principle in quantum mechanics is a fundamental relation with different forms, including Heisenberg's uncertainty relation and Schrödinger's uncertainty relation. We introduce the generalized Wigner-Yanase-Dyson correlation and the related quantities. Various properties of them are discussed. Finally, we establish several generalizations of uncertainty relation expressed in terms of the generalized Wigner-Yanase-Dyson skew information.

Diversifying the composition and structure of managed late-successional forests with harvest gaps: What is the optimal gap size?

Treesearch

Christel C. Kern; Anthony W. D’Amato; Terry F. Strong

2013-01-01

Managing forests for resilience is crucial in the face of uncertain future environmental conditions. Because harvest gap size alters the species diversity and vertical and horizontal structural heterogeneity, there may be an optimum range of gap sizes for conferring resilience to environmental uncertainty. We examined the impacts of different harvest gap sizes on...

Human Time-Frequency Acuity Beats the Fourier Uncertainty Principle

NASA Astrophysics Data System (ADS)

Oppenheim, Jacob N.; Magnasco, Marcelo O.

2013-01-01

The time-frequency uncertainty principle states that the product of the temporal and frequency extents of a signal cannot be smaller than 1/(4π). We study human ability to simultaneously judge the frequency and the timing of a sound. Our subjects often exceeded the uncertainty limit, sometimes by more than tenfold, mostly through remarkable timing acuity. Our results establish a lower bound for the nonlinearity and complexity of the algorithms employed by our brains in parsing transient sounds, rule out simple “linear filter” models of early auditory processing, and highlight timing acuity as a central feature in auditory object processing.

"Citizen Jane": Rethinking Design Principles for Closing the Gender Gap in Computing.

ERIC Educational Resources Information Center

Raphael, Chad

This paper identifies three rationales in the relevant literature for closing the gender gap in computing: economic, cultural and political. Each rationale implies a different set of indicators of present inequalities, disparate goals for creating equality, and distinct principles for software and web site design that aims to help girls overcome…

Other ways of measuring `Big G'

NASA Astrophysics Data System (ADS)

Rothleitner, Christian

2016-03-01

In 1798, the British scientist Henry Cavendish performed the first laboratory experiment to determine the gravitational force between two massive bodies. From his result, Newton's gravitational constant, G, was calculated. Cavendish's measurement principle was the torsion balance invented by John Michell some 15 years before. During the following two centuries, more than 300 new measurements followed. Although technology - and physics - developed rapidly during this time, surprisingly, most experiments were still based on the same principle. In fact, the most accurate determination of G to date is a measurement based on the torsion balance principle. Despite the fact that G was one of the first fundamental physical constants ever measured, and despite the huge number of experiments performed on it to this day, its CODATA recommended value still has the highest standard measurement uncertainty when compared to other fundamental physical constants. Even more serious is the fact that even measurements based on the same principle often do not overlap within their attributed standard uncertainties. It must be assumed that various experiments are subject to one or more unknown biases. In this talk I will present some alternative experimental setups to the torsion balance which have been performed or proposed to measure G. Although their estimated uncertainties are often higher than most torsion balance experiments, revisiting such ideas is worthwhile. Advances in technology could offer solutions to problems which were previously insurmountable, these solutions could result in lower measurement uncertainties. New measurement principles could also help to uncover hidden systematic effects.

Plant canopy gap-size analysis theory for improving optical measurements of leaf-area index

NASA Astrophysics Data System (ADS)

Chen, Jing M.; Cihlar, Josef

1995-09-01

Optical instruments currently available for measuring the leaf-area index (LAI) of a plant canopy all utilize only the canopy gap-fraction information. These instruments include the Li-Cor LAI-2000 Plant Canopy Analyzer, Decagon, and Demon. The advantages of utilizing both the canopy gap-fraction and gap-size information are shown. For the purpose of measuring the canopy gap size, a prototype sunfleck-LAI instrument named Tracing Radiation and Architecture of Canopies (TRAC), has been developed and tested in two pure conifer plantations, red pine (Pinus resinosa Ait.) and jack pine (Pinus banksiana Lamb). A new gap-size-analysis theory is presented to quantify the effect of canopy architecture on optical measurements of LAI based on the gap-fraction principle. The theory is an improvement on that of Lang and Xiang [Agric. For. Meteorol. 37, 229 (1986)]. In principle, this theory can be used for any heterogeneous canopies.

On entropic uncertainty relations in the presence of a minimal length

NASA Astrophysics Data System (ADS)

Rastegin, Alexey E.

2017-07-01

Entropic uncertainty relations for the position and momentum within the generalized uncertainty principle are examined. Studies of this principle are motivated by the existence of a minimal observable length. Then the position and momentum operators satisfy the modified commutation relation, for which more than one algebraic representation is known. One of them is described by auxiliary momentum so that the momentum and coordinate wave functions are connected by the Fourier transform. However, the probability density functions of the physically true and auxiliary momenta are different. As the corresponding entropies differ, known entropic uncertainty relations are changed. Using differential Shannon entropies, we give a state-dependent formulation with correction term. State-independent uncertainty relations are obtained in terms of the Rényi entropies and the Tsallis entropies with binning. Such relations allow one to take into account a finiteness of measurement resolution.

On the action of Heisenberg's uncertainty principle in discrete linear methods for calculating the components of the deflection of the vertical

NASA Astrophysics Data System (ADS)

Mazurova, Elena; Lapshin, Aleksey

2013-04-01

The method of discrete linear transformations that can be implemented through the algorithms of the Standard Fourier Transform (SFT), Short-Time Fourier Transform (STFT) or Wavelet transform (WT) is effective for calculating the components of the deflection of the vertical from discrete values of gravity anomaly. The SFT due to the action of Heisenberg's uncertainty principle indicates weak spatial localization that manifests in the following: firstly, it is necessary to know the initial digital signal on the complete number line (in case of one-dimensional transform) or in the whole two-dimensional space (if a two-dimensional transform is performed) in order to find the SFT. Secondly, the localization and values of the "peaks" of the initial function cannot be derived from its Fourier transform as the coefficients of the Fourier transform are formed by taking into account all the values of the initial function. Thus, the SFT gives the global information on all frequencies available in the digital signal throughout the whole time period. To overcome this peculiarity it is necessary to localize the signal in time and apply the Fourier transform only to a small portion of the signal; the STFT that differs from the SFT only by the presence of an additional factor (window) is used for this purpose. A narrow enough window is chosen to localize the signal in time and, according to Heisenberg's uncertainty principle, it results in have significant enough uncertainty in frequency. If one chooses a wide enough window it, according to the same principle, will increase time uncertainty. Thus, if the signal is narrowly localized in time its spectrum, on the contrary, is spread on the complete axis of frequencies, and vice versa. The STFT makes it possible to improve spatial localization, that is, it allows one to define the presence of any frequency in the signal and the interval of its presence. However, owing to Heisenberg's uncertainty principle, it is impossible to tell precisely, what frequency is present in the signal at the current moment of time: it is possible to speak only about the range of frequencies. Besides, it is impossible to specify precisely the time moment of the presence of this or that frequency: it is possible to speak only about the time frame. It is this feature that imposes major constrains on the applicability of the STFT. In spite of the fact that the problems of resolution in time and frequency result from a physical phenomenon (Heisenberg's uncertainty principle) and exist independent of the transform applied, there is a possibility to analyze any signal, using the alternative approach - the multiresolutional analysis (MRA). The wavelet-transform is one of the methods for making a MRA-type analysis. Thanks to it, low frequencies can be shown in a more detailed form with respect to time, and high ones - with respect to frequency. The paper presents the results of calculating of the components of the deflection of the vertical, done by the SFT, STFT and WT. The results are presented in the form of 3-d models that visually show the action of Heisenberg's uncertainty principle in the specified algorithms. The research conducted allows us to recommend the application of wavelet-transform to calculate of the components of the deflection of the vertical in the near-field zone. Keywords: Standard Fourier Transform, Short-Time Fourier Transform, Wavelet Transform, Heisenberg's uncertainty principle.

Chemical carcinogens: a review of the science and its associated principles. U.S. Interagency Staff Group on Carcinogens.

PubMed Central

1986-01-01

In order to articulate a view of chemical carcinogenesis that scientists generally hold in common today and to draw upon this understanding to compose guiding principles that can be used as a bases for the efforts of the regulatory agencies to establish guidelines for assessing carcinogenic risk to meet the specific requirements of the legislative acts they are charged to implement, the Office of Science and Technology Policy, Executive Office, the White House drew on the expertise of a number of regulatory agencies to elucidate present scientific views in critical areas of the major disciplines important to the process of risk assessment. The document is composed of two major sections, Principles and the State-of-the-Science. The latter consists of subsections on the mechanisms of carcinogenesis, short-term and long-term testing, and epidemiology, which are important components in the risk assessment step of hazard identification. These subsections are followed by one on exposure assessment, and a final section which includes analyses of dose-response (hazard) assessment and risk characterization. The principles are derived from considerations in each of the subsections. Because of present gaps in understanding, the principles contain judgmental (science policy) decisions on major unresolved issues as well as statements of what is generally accepted as fact. These judgments are basically assumptions which are responsible for much of the uncertainty in the process of risk assessment. There was an attempt to clearly distinguish policy and fact. The subsections of the State-of-the-Science portion provide the underlying support to the principles articulated, and to read the "Principles" section without a full appreciation of the State-of-the-Science section is to invite oversimplification and misinterpretation. Finally, suggestions are made for future research efforts which will improve the process of risk assessment. PMID:3530737

Bayesian-information-gap decision theory with an application to CO 2 sequestration

DOE PAGES

O'Malley, D.; Vesselinov, V. V.

2015-09-04

Decisions related to subsurface engineering problems such as groundwater management, fossil fuel production, and geologic carbon sequestration are frequently challenging because of an overabundance of uncertainties (related to conceptualizations, parameters, observations, etc.). Because of the importance of these problems to agriculture, energy, and the climate (respectively), good decisions that are scientifically defensible must be made despite the uncertainties. We describe a general approach to making decisions for challenging problems such as these in the presence of severe uncertainties that combines probabilistic and non-probabilistic methods. The approach uses Bayesian sampling to assess parametric uncertainty and Information-Gap Decision Theory (IGDT) to addressmore » model inadequacy. The combined approach also resolves an issue that frequently arises when applying Bayesian methods to real-world engineering problems related to the enumeration of possible outcomes. In the case of zero non-probabilistic uncertainty, the method reduces to a Bayesian method. Lastly, to illustrate the approach, we apply it to a site-selection decision for geologic CO 2 sequestration.« less

Lyme disease ecology in a changing world: Consensus, uncertainty and critical gaps for improving control

USGS Publications Warehouse

Kilpatrick, A. Marm; Dobson, Andrew D.M.; Levi, Taal; Salkeld, Daniel J.; Swei, Andrea; Ginsberg, Howard; Kjemtrup, Anne; Padgett, Kerry A.; Jensen, Per A.; Fish, Durland; Ogden, Nick H.; Diuk-Wasser, Maria A.

2017-01-01

Lyme disease is the most common tick-borne disease in temperate regions of North America, Europe and Asia, and the number of reported cases has increased in many regions as landscapes have been altered. Although there has been extensive work on the ecology and epidemiology of this disease in both Europe and North America, substantial uncertainty exists about fundamental aspects that determine spatial and temporal variation in both disease risk and human incidence, which hamper effective and efficient prevention and control. Here we describe areas of consensus that can be built on, identify areas of uncertainty and outline research needed to fill these gaps to facilitate predictive models of disease risk and the development of novel disease control strategies. Key areas of uncertainty include: (i) the precise influence of deer abundance on tick abundance, (ii) how tick populations are regulated, (iii) assembly of host communities and tick-feeding patterns across different habitats, (iv) reservoir competence of host species, and (v) pathogenicity for humans of different genotypes of Borrelia burgdorferi. Filling these knowledge gaps will improve Lyme disease prevention and control and provide general insights into the drivers and dynamics of this emblematic multi-host–vector-borne zoonotic disease.

IceCube SWIRP

NASA Technical Reports Server (NTRS)

Wu, Dongliang L.

2017-01-01

Clouds, ice clouds in particular, are a major source of uncertainty in climate models. Submm-wave sensors fill the sensitivity gap between MW and IR.Cloud microphysical properties (particle size and shape) account for large (200 and 40) measurement uncertainty.

Complementarity and Compensation: Bridging the Gap between Writing and Design.

ERIC Educational Resources Information Center

Killingsworth, M. Jimmie; Sanders, Scott P.

1990-01-01

Outlines two rhetorical principles for producing iconic-mosaic texts--the principle of complementarity and the principle of compensation. Shows how these principles can be applied to practical problems in coordinating the writing and design processes in student projects. (RS)

Tightening the entropic uncertainty bound in the presence of quantum memory

NASA Astrophysics Data System (ADS)

Adabi, F.; Salimi, S.; Haseli, S.

2016-06-01

The uncertainty principle is a fundamental principle in quantum physics. It implies that the measurement outcomes of two incompatible observables cannot be predicted simultaneously. In quantum information theory, this principle can be expressed in terms of entropic measures. M. Berta et al. [Nat. Phys. 6, 659 (2010), 10.1038/nphys1734] have indicated that uncertainty bound can be altered by considering a particle as a quantum memory correlating with the primary particle. In this article, we obtain a lower bound for entropic uncertainty in the presence of a quantum memory by adding an additional term depending on the Holevo quantity and mutual information. We conclude that our lower bound will be tightened with respect to that of Berta et al. when the accessible information about measurements outcomes is less than the mutual information about the joint state. Some examples have been investigated for which our lower bound is tighter than Berta et al.'s lower bound. Using our lower bound, a lower bound for the entanglement of formation of bipartite quantum states has been obtained, as well as an upper bound for the regularized distillable common randomness.

Measurement of optical to electrical and electrical to optical delays with ps-level uncertainty.

PubMed

Peek, H Z; Pinkert, T J; Jansweijer, P P M; Koelemeij, J C J

2018-05-28

We present a new measurement principle to determine the absolute time delay of a waveform from an optical reference plane to an electrical reference plane and vice versa. We demonstrate a method based on this principle with 2 ps uncertainty. This method can be used to perform accurate time delay determinations of optical transceivers used in fiber-optic time-dissemination equipment. As a result the time scales in optical and electrical domain can be related to each other with the same uncertainty. We expect this method will be a new breakthrough in high-accuracy time transfer and absolute calibration of time-transfer equipment.

Thermal Conductivity and Large Isotope Effect in GaN from First Principles

DTIC Science & Technology

2012-08-28

August 2012) We present atomistic first principles results for the lattice thermal conductivity of GaN and compare them to those for GaP, GaAs, and GaSb ...weak scattering results from stiff atomic bonds and the large Ga to N mass ratio, which give phonons high frequencies and also a pronounced energy gap...66.70.f, 63.20.kg, 71.15.m Introduction.—Gallium nitride (GaN) is a wide band gap semiconductor and a promising candidate for use in opto- electronic

An info-gap application to robust design of a prestressed space structure under epistemic uncertainties

NASA Astrophysics Data System (ADS)

Hot, Aurélien; Weisser, Thomas; Cogan, Scott

2017-07-01

Uncertainty quantification is an integral part of the model validation process and is important to take into account during the design of mechanical systems. Sources of uncertainty are diverse but generally fall into two categories: aleatory due to random process and epistemic resulting from a lack of knowledge. This work focuses on the behavior of solar arrays in their stowed configuration. To avoid impacts during launch, snubbers are used to prestress the panels. Since the mechanical properties of the snubbers and the associated preload configurations are difficult to characterize precisely, an info-gap approach is proposed to investigate the influence of such uncertainties on design configurations obtained for different values of safety factors. This eventually allows to revise the typical values of these factors and to reevaluate them with respect to a targeted robustness level. The proposed methodology is illustrated using a simplified finite element model of a solar array.

Evanescent radiation, quantum mechanics and the Casimir effect

NASA Technical Reports Server (NTRS)

Schatten, Kenneth H.

1989-01-01

An attempt to bridge the gap between classical and quantum mechanics and to explain the Casimir effect is presented. The general nature of chaotic motion is discussed from two points of view: the first uses catastrophe theory and strange attractors to describe the deterministic view of this motion; the underlying framework for chaos in these classical dynamic systems is their extreme sensitivity to initial conditions. The second interpretation refers to randomness associated with probabilistic dynamics, as for Brownian motion. The present approach to understanding evanescent radiation and its relation to the Casimir effect corresponds to the first interpretation, whereas stochastic electrodynamics corresponds to the second viewpoint. The nonlinear behavior of the electromagnetic field is also studied. This well-understood behavior is utilized to examine the motions of two orbiting charges and shows a closeness between the classical behavior and the quantum uncertainty principle. The evanescent radiation is used to help explain the Casimir effect.

Generalized uncertainty principle and the maximum mass of ideal white dwarfs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rashidi, Reza, E-mail: reza.rashidi@srttu.edu

The effects of a generalized uncertainty principle on the structure of an ideal white dwarf star is investigated. The equation describing the equilibrium configuration of the star is a generalized form of the Lane–Emden equation. It is proved that the star always has a finite size. It is then argued that the maximum mass of such an ideal white dwarf tends to infinity, as opposed to the conventional case where it has a finite value.

Risk, Uncertainty and Precaution in Science: The Threshold of the Toxicological Concern Approach in Food Toxicology.

PubMed

Bschir, Karim

2017-04-01

Environmental risk assessment is often affected by severe uncertainty. The frequently invoked precautionary principle helps to guide risk assessment and decision-making in the face of scientific uncertainty. In many contexts, however, uncertainties play a role not only in the application of scientific models but also in their development. Building on recent literature in the philosophy of science, this paper argues that precaution should be exercised at the stage when tools for risk assessment are developed as well as when they are used to inform decision-making. The relevance and consequences of this claim are discussed in the context of the threshold of the toxicological concern approach in food toxicology. I conclude that the approach does not meet the standards of an epistemic version of the precautionary principle.

The strain induced band gap modulation from narrow gap semiconductor to half-metal on Ti{sub 2}CrGe: A first principles study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jia, E-mail: jiali@hebut.edu.cn; Research Institute for Energy Equipment Materials, Hebei University of Technology, Tianjin 300401; Zhang, Zhidong

The Heusler alloy Ti{sub 2}CrGe is a stable L2{sub 1} phase with antiferromagnetic ordering. With band-gap energy (∼ 0.18 eV) obtained from a first-principles calculation, it belongs to the group of narrow band gap semiconductor. The band-gap energy decreases with increasing lattice compression and disappears until a strain of −5%; moreover, gap contraction only occurs in the spin-down states, leading to half-metallic character at the −5% strain. The Ti{sub 1}, Ti{sub 2}, and Cr moments all exhibit linear changes in behavior within strains of −5%– +5%. Nevertheless, the total zero moment is robust for these strains. The imaginary part ofmore » the dielectric function for both up and down spin states shows a clear onset energy, indicating a corresponding electronic gap for the two spin channels.« less

The energy-time uncertainty principle and the EPR paradox: Experiments involving correlated two-photon emission in parametric down-conversion

NASA Technical Reports Server (NTRS)

Chiao, Raymond Y.; Kwiat, Paul G.; Steinberg, Aephraim M.

1992-01-01

The energy-time uncertainty principle is on a different footing than the momentum position uncertainty principle: in contrast to position, time is a c-number parameter, and not an operator. As Aharonov and Bohm have pointed out, this leads to different interpretations of the two uncertainty principles. In particular, one must distinguish between an inner and an outer time in the definition of the spread in time, delta t. It is the inner time which enters the energy-time uncertainty principle. We have checked this by means of a correlated two-photon light source in which the individual energies of the two photons are broad in spectra, but in which their sum is sharp. In other words, the pair of photons is in an entangled state of energy. By passing one member of the photon pair through a filter with width delta E, it is observed that the other member's wave packet collapses upon coincidence detection to a duration delta t, such that delta E(delta t) is approximately equal to planks constant/2 pi, where this duration delta t is an inner time, in the sense of Aharonov and Bohm. We have measured delta t by means of a Michelson interferometer by monitoring the visibility of the fringes seen in coincidence detection. This is a nonlocal effect, in the sense that the two photons are far away from each other when the collapse occurs. We have excluded classical-wave explanations of this effect by means of triple coincidence measurements in conjunction with a beam splitter which follows the Michelson interferometer. Since Bell's inequalities are known to be violated, we believe that it is also incorrect to interpret this experimental outcome as if energy were a local hidden variable, i.e., as if each photon, viewed as a particle, possessed some definite but unknown energy before its detection.

Robust climate policies under uncertainty: a comparison of robust decision making and info-gap methods.

PubMed

Hall, Jim W; Lempert, Robert J; Keller, Klaus; Hackbarth, Andrew; Mijere, Christophe; McInerney, David J

2012-10-01

This study compares two widely used approaches for robustness analysis of decision problems: the info-gap method originally developed by Ben-Haim and the robust decision making (RDM) approach originally developed by Lempert, Popper, and Bankes. The study uses each approach to evaluate alternative paths for climate-altering greenhouse gas emissions given the potential for nonlinear threshold responses in the climate system, significant uncertainty about such a threshold response and a variety of other key parameters, as well as the ability to learn about any threshold responses over time. Info-gap and RDM share many similarities. Both represent uncertainty as sets of multiple plausible futures, and both seek to identify robust strategies whose performance is insensitive to uncertainties. Yet they also exhibit important differences, as they arrange their analyses in different orders, treat losses and gains in different ways, and take different approaches to imprecise probabilistic information. The study finds that the two approaches reach similar but not identical policy recommendations and that their differing attributes raise important questions about their appropriate roles in decision support applications. The comparison not only improves understanding of these specific methods, it also suggests some broader insights into robustness approaches and a framework for comparing them. © 2012 RAND Corporation.

Generalized uncertainty principles and quantum field theory

NASA Astrophysics Data System (ADS)

Husain, Viqar; Kothawala, Dawood; Seahra, Sanjeev S.

2013-01-01

Quantum mechanics with a generalized uncertainty principle arises through a representation of the commutator [x^,p^]=if(p^). We apply this deformed quantization to free scalar field theory for f±=1±βp2. The resulting quantum field theories have a rich fine scale structure. For small wavelength modes, the Green’s function for f+ exhibits a remarkable transition from Lorentz to Galilean invariance, whereas for f- such modes effectively do not propagate. For both cases Lorentz invariance is recovered at long wavelengths.

The uncertainty principle and quantum chaos

NASA Technical Reports Server (NTRS)

Chirikov, Boris V.

1993-01-01

The conception of quantum chaos is described in some detail. The most striking feature of this novel phenomenon is that all the properties of classical dynamical chaos persist here but, typically, on the finite and different time scales only. The ultimate origin of such a universal quantum stability is in the fundamental uncertainty principle which makes discrete the phase space and, hence, the spectrum of bounded quantum motion. Reformulation of the ergodic theory, as a part of the general theory of dynamical systems, is briefly discussed.

GUP parameter from quantum corrections to the Newtonian potential

NASA Astrophysics Data System (ADS)

Scardigli, Fabio; Lambiase, Gaetano; Vagenas, Elias C.

2017-04-01

We propose a technique to compute the deformation parameter of the generalized uncertainty principle by using the leading quantum corrections to the Newtonian potential. We just assume General Relativity as theory of Gravitation, and the thermal nature of the GUP corrections to the Hawking spectrum. With these minimal assumptions our calculation gives, to first order, a specific numerical result. The physical meaning of this value is discussed, and compared with the previously obtained bounds on the generalized uncertainty principle deformation parameter.

Design of crusher liner based on time - varying uncertainty theory

NASA Astrophysics Data System (ADS)

Tang, J. C.; Shi, B. Q.; Yu, H. J.; Wang, R. J.; Zhang, W. Y.

2017-09-01

This article puts forward the time-dependent design method considering the load fluctuation factors for the liner based on the time-varying uncertainty theory. In this method, the time-varying uncertainty design model of liner is constructed by introducing the parameters that affect the wear rate, the volatility and the drift rate. Based on the design example, the timevarying design outline of the moving cone liner is obtained. Based on the theory of minimum wear, the gap curve of wear resistant cavity is designed, and the optimized cavity is obtained by the combination of the thickness of the cone and the cavity gap. Taking the PYGB1821 multi cylinder hydraulic cone crusher as an example, it is proved that the service life of the new liner is improved by more than 14.3%.

Quantifying uncertainty in read-across assessment – an algorithmic approach - (SOT)

EPA Science Inventory

Read-across is a popular data gap filling technique within category and analogue approaches for regulatory purposes. Acceptance of read-across remains an ongoing challenge with several efforts underway for identifying and addressing uncertainties. Here we demonstrate an algorithm...

A Strategy for Uncertainty Visualization Design

DTIC Science & Technology

2009-10-01

143–156, Magdeburg , Germany . [11] Thomson, J., Hetzler, E., MacEachren, A., Gahegan, M. and Pavel, M. (2005), A Typology for Visualizing Uncertainty...and Stasko [20] to bridge analytic gaps in visualization design, when tasks in the strategy overlap (and therefore complement) design frameworks

Computing the Entropy of Kerr-Newman Black Hole Without Brick Walls Method

NASA Astrophysics Data System (ADS)

Zhang, Li-Chun; Wu, Yue-Qin; Li, Huai-Fan; Ren, Zhao

By using the entanglement entropy method, the statistical entropy of the Bose and Fermi fields in a thin film is calculated and the Bekenstein-Hawking entropy of Kerr-Newman black hole is obtained. Here, the Bose and Fermi fields are entangled with the quantum states in Kerr-Newman black hole and are outside of the horizon. The divergence of brick-wall model is avoided without any cutoff by the new equation of state density obtained with the generalized uncertainty principle. The calculation implies that the high density quantum states near the event horizon are strongly correlated with the quantum states in black hole. The black hole entropy is a quantum effect. It is an intrinsic characteristic of space-time. The ultraviolet cutoff in the brick-wall model is unreasonable. The generalized uncertainty principle should be considered in the high energy quantum field near the event horizon. From the calculation, the constant λ introduced in the generalized uncertainty principle is related to polar angle θ in an axisymmetric space-time.

On the relativity and uncertainty of distance, time, and energy measurements by man. (1) Derivation of the Weber psychophysical law from the Heisenberg uncertainty principle applied to a superconductive biological detector. (2) The reverse derivation. (3) A human theory of relativity.

PubMed

Cope, F W

1981-01-01

The Weber psychophysical law, which describes much experimental data on perception by man, is derived from the Heisenberg uncertainty principle on the assumption that human perception occurs by energy detection by superconductive microregions within man . This suggests that psychophysical perception by man might be considered merely a special case of physical measurement in general. The reverse derivation-i.e., derivation of the Heisenberg principle from the Weber law-may be of even greater interest. It suggest that physical measurements could be regarded as relative to the perceptions by the detectors within man. Thus one may develop a "human" theory of relativity that could have the advantage of eliminating hidden assumptions by forcing physical theories to conform more completely to the measurements made by man rather than to concepts that might not accurately describe nature.

A study of the influence of forest gaps on fire–atmosphere interactions

Treesearch

Michael T. Kiefer; Warren E. Heilman; Shiyuan Zhong; Joseph J. (Jay) Charney; Xindi (Randy) Bian

2016-01-01

Much uncertainty exists regarding the possible role that gaps in forest canopies play in modulating fire–atmosphere interactions in otherwise horizontally homogeneous forests. This study examines the influence of gaps in forest canopies on atmospheric perturbations induced by a low-intensity fire using the ARPS-CANOPY model, a version of the Advanced Regional...

Identifying gaps in conservation networks: of indicators and uncertainty in geographic-based analyses

Treesearch

Curtis H. Flather; Kenneth R. Wilson; Denis J. Dean; William C. McComb

1997-01-01

Mapping of biodiversity elements to expose gaps in. conservation networks has become a common strategy in nature-reserve design. We review a set of critical assumptions and issues that influence the interpretation and implementation of gap analysis, including: (1) the assumption that a subset of taxa can be used to indicate overall diversity patterns, and (2) the...

Info-gap theory and robust design of surveillance for invasive species: the case study of Barrow Island.

PubMed

Davidovitch, Lior; Stoklosa, Richard; Majer, Jonathan; Nietrzeba, Alex; Whittle, Peter; Mengersen, Kerrie; Ben-Haim, Yakov

2009-06-01

Surveillance for invasive non-indigenous species (NIS) is an integral part of a quarantine system. Estimating the efficiency of a surveillance strategy relies on many uncertain parameters estimated by experts, such as the efficiency of its components in face of the specific NIS, the ability of the NIS to inhabit different environments, and so on. Due to the importance of detecting an invasive NIS within a critical period of time, it is crucial that these uncertainties be accounted for in the design of the surveillance system. We formulate a detection model that takes into account, in addition to structured sampling for incursive NIS, incidental detection by untrained workers. We use info-gap theory for satisficing (not minimizing) the probability of detection, while at the same time maximizing the robustness to uncertainty. We demonstrate the trade-off between robustness to uncertainty, and an increase in the required probability of detection. An empirical example based on the detection of Pheidole megacephala on Barrow Island demonstrates the use of info-gap analysis to select a surveillance strategy.

29 CFR 1608.1 - Statement of purpose.

Code of Federal Regulations, 2010 CFR

2010-07-01

... upon the principles of title VII. Any uncertainty as to the meaning and application of title VII in... Commission believes that it is now necessary to clarify and harmonize the principles of title VII in order to... who comply with the principles of title VII. (b) Purposes of title VII. Congress enacted title VII in...

Precautionary Principles: General Definitions and Specific Applications to Genetically Modified Organisms

ERIC Educational Resources Information Center

Lofstedt, Ragnar E.; Fischhoff, Baruch; Fischhoff, Ilya R.

2002-01-01

Precautionary principles have been proposed as a fundamental element of sound risk management. Their advocates see them as guiding action in the face of uncertainty, encouraging the adoption of measures that reduce serious risks to health, safety, and the environment. Their opponents may reject the very idea of precautionary principles, find…

Experimental and first-principles calculation study of the pressure-induced transitions to a metastable phase in GaP O4 and in the solid solution AlP O4-GaP O4

NASA Astrophysics Data System (ADS)

Angot, E.; Huang, B.; Levelut, C.; Le Parc, R.; Hermet, P.; Pereira, A. S.; Aquilanti, G.; Frapper, G.; Cambon, O.; Haines, J.

2017-08-01

α -Quartz-type gallium phosphate and representative compositions in the AlP O4-GaP O4 solid solution were studied by x-ray powder diffraction and absorption spectroscopy, Raman scattering, and by first-principles calculations up to pressures of close to 30 GPa. A phase transition to a metastable orthorhombic high-pressure phase along with some of the stable orthorhombic C m c m CrV O4 -type material is found to occur beginning at 9 GPa at 320 ∘C in GaP O4 . In the case of the AlP O4-GaP O4 solid solution at room temperature, only the metastable orthorhombic phase was obtained above 10 GPa. The possible crystal structures of the high-pressure forms of GaP O4 were predicted from first-principles calculations and the evolutionary algorithm USPEX. A predicted orthorhombic structure with a P m n 21 space group with the gallium in sixfold and phosphorus in fourfold coordination was found to be in the best agreement with the combined experimental data from x-ray diffraction and absorption and Raman spectroscopy. This method is found to very powerful to better understand competition between different phase transition pathways at high pressure.

Theoretical study of band gap in CuAlO2: Pressure dependence and self-interaction correction

NASA Astrophysics Data System (ADS)

Nakanishi, Akitaka; Katayama-Yoshida, Hiroshi

2012-08-01

By using first-principles calculations, we studied the energy gaps of delafossite CuAlO2: (1) pressure dependence and (2) self-interaction correction (SIC). Our simulation shows that CuAlO2 transforms from a delafossite structure to a leaning delafossite structure at 60 GPa. The energy gap of CuAlO2 increases through the structural transition due to the enhanced covalency of Cu 3d and O 2p states. We implemented a self-interaction correction (SIC) into first-principles calculation code to go beyond local density approximation and applied it to CuAlO2. The energy gap calculated within the SIC is close to experimental data while one calculated without the SIC is about 1 eV smaller than the experimental data.

Strong interplay between structure and electronic properties in CuIn(S,Se){2}: a first-principles study.

PubMed

Vidal, Julien; Botti, Silvana; Olsson, Pär; Guillemoles, Jean-François; Reining, Lucia

2010-02-05

We present a first-principles study of the electronic properties of CuIn(S,Se){2} (CIS) using state-of-the-art self-consistent GW and hybrid functionals. The calculated band gap depends strongly on the anion displacement u, an internal structural parameter that measures lattice distortion. This contrasts with the observed stability of the band gap of CIS solar panels under operating conditions, where a relatively large dispersion of values for u occurs. We solve this apparent paradox considering the coupled effect on the band gap of copper vacancies and lattice distortions. The correct treatment of d electrons in these materials requires going beyond density functional theory, and GW self-consistency is critical to evaluate the quasiparticle gap and the valence band maximum.

Dynamics of non-holonomic systems with stochastic transport

NASA Astrophysics Data System (ADS)

Holm, D. D.; Putkaradze, V.

2018-01-01

This paper formulates a variational approach for treating observational uncertainty and/or computational model errors as stochastic transport in dynamical systems governed by action principles under non-holonomic constraints. For this purpose, we derive, analyse and numerically study the example of an unbalanced spherical ball rolling under gravity along a stochastic path. Our approach uses the Hamilton-Pontryagin variational principle, constrained by a stochastic rolling condition, which we show is equivalent to the corresponding stochastic Lagrange-d'Alembert principle. In the example of the rolling ball, the stochasticity represents uncertainty in the observation and/or error in the computational simulation of the angular velocity of rolling. The influence of the stochasticity on the deterministically conserved quantities is investigated both analytically and numerically. Our approach applies to a wide variety of stochastic, non-holonomically constrained systems, because it preserves the mathematical properties inherited from the variational principle.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zozor, Steeve; Portesi, Mariela; Sanchez-Moreno, Pablo

The position-momentum uncertainty-like inequality based on moments of arbitrary order for d-dimensional quantum systems, which is a generalization of the celebrated Heisenberg formulation of the uncertainty principle, is improved here by use of the Renyi-entropy-based uncertainty relation. The accuracy of the resulting lower bound is physico-computationally analyzed for the two main prototypes in d-dimensional physics: the hydrogenic and oscillator-like systems.

Application of Risk Management and Uncertainty Concepts and Methods for Ecosystem Restoration: Principles and Best Practice

DTIC Science & Technology

2012-08-01

habitats for specific species of trout . The report noted that these uncertainties — and the SMEs, who had past experience in such topic areas — were...reduce uncertainty in HREP projects is reflected in the completion of the Pool 11 Islands (UMRS RM 583-593) HREP in 2003. In 1989 the Browns Lake

Generalized Entropic Uncertainty Relations with Tsallis' Entropy

NASA Technical Reports Server (NTRS)

Portesi, M.; Plastino, A.

1996-01-01

A generalization of the entropic formulation of the Uncertainty Principle of Quantum Mechanics is considered with the introduction of the q-entropies recently proposed by Tsallis. The concomitant generalized measure is illustrated for the case of phase and number operators in quantum optics. Interesting results are obtained when making use of q-entropies as the basis for constructing generalized entropic uncertainty measures.

Entropic Uncertainty Relation and Information Exclusion Relation for multiple measurements in the presence of quantum memory

NASA Astrophysics Data System (ADS)

Zhang, Jun; Zhang, Yang; Yu, Chang-Shui

2015-06-01

The Heisenberg uncertainty principle shows that no one can specify the values of the non-commuting canonically conjugated variables simultaneously. However, the uncertainty relation is usually applied to two incompatible measurements. We present tighter bounds on both entropic uncertainty relation and information exclusion relation for multiple measurements in the presence of quantum memory. As applications, three incompatible measurements on Werner state and Horodecki’s bound entangled state are investigated in details.

Lyme disease ecology in a changing world: consensus, uncertainty and critical gaps for improving control

PubMed Central

Dobson, Andrew D. M.; Levi, Taal; Salkeld, Daniel J.; Swei, Andrea; Ginsberg, Howard S.; Kjemtrup, Anne; Padgett, Kerry A.; Jensen, Per M.; Fish, Durland; Ogden, Nick H.

2017-01-01

Lyme disease is the most common tick-borne disease in temperate regions of North America, Europe and Asia, and the number of reported cases has increased in many regions as landscapes have been altered. Although there has been extensive work on the ecology and epidemiology of this disease in both Europe and North America, substantial uncertainty exists about fundamental aspects that determine spatial and temporal variation in both disease risk and human incidence, which hamper effective and efficient prevention and control. Here we describe areas of consensus that can be built on, identify areas of uncertainty and outline research needed to fill these gaps to facilitate predictive models of disease risk and the development of novel disease control strategies. Key areas of uncertainty include: (i) the precise influence of deer abundance on tick abundance, (ii) how tick populations are regulated, (iii) assembly of host communities and tick-feeding patterns across different habitats, (iv) reservoir competence of host species, and (v) pathogenicity for humans of different genotypes of Borrelia burgdorferi. Filling these knowledge gaps will improve Lyme disease prevention and control and provide general insights into the drivers and dynamics of this emblematic multi-host–vector-borne zoonotic disease. This article is part of the themed issue ‘Conservation, biodiversity and infectious disease: scientific evidence and policy implications'. PMID:28438910

Routine internal- and external-quality control data in clinical laboratories for estimating measurement and diagnostic uncertainty using GUM principles.

PubMed

Magnusson, Bertil; Ossowicki, Haakan; Rienitz, Olaf; Theodorsson, Elvar

2012-05-01

Healthcare laboratories are increasingly joining into larger laboratory organizations encompassing several physical laboratories. This caters for important new opportunities for re-defining the concept of a 'laboratory' to encompass all laboratories and measurement methods measuring the same measurand for a population of patients. In order to make measurement results, comparable bias should be minimized or eliminated and measurement uncertainty properly evaluated for all methods used for a particular patient population. The measurement as well as diagnostic uncertainty can be evaluated from internal and external quality control results using GUM principles. In this paper the uncertainty evaluations are described in detail using only two main components, within-laboratory reproducibility and uncertainty of the bias component according to a Nordtest guideline. The evaluation is exemplified for the determination of creatinine in serum for a conglomerate of laboratories both expressed in absolute units (μmol/L) and relative (%). An expanded measurement uncertainty of 12 μmol/L associated with concentrations of creatinine below 120 μmol/L and of 10% associated with concentrations above 120 μmol/L was estimated. The diagnostic uncertainty encompasses both measurement uncertainty and biological variation, and can be estimated for a single value and for a difference. This diagnostic uncertainty for the difference for two samples from the same patient was determined to be 14 μmol/L associated with concentrations of creatinine below 100 μmol/L and 14 % associated with concentrations above 100 μmol/L.

Air Pollution and Health: Bridging the Gap from Health Outcomes: Conference Summary

EPA Science Inventory

“Air Pollution and Health: Bridging the Gap from Sources to Health Outcomes,” an international specialty conference sponsored by the American Association for Aerosol Research, was held to address key uncertainties in our understanding of adverse health effects related to air po...

On the Monte Carlo simulation of electron transport in the sub-1 keV energy range.

PubMed

Thomson, Rowan M; Kawrakow, Iwan

2011-08-01

The validity of "classic" Monte Carlo (MC) simulations of electron and positron transport at sub-1 keV energies is investigated in the context of quantum theory. Quantum theory dictates that uncertainties on the position and energy-momentum four-vectors of radiation quanta obey Heisenberg's uncertainty relation; however, these uncertainties are neglected in "classical" MC simulations of radiation transport in which position and momentum are known precisely. Using the quantum uncertainty relation and electron mean free path, the magnitudes of uncertainties on electron position and momentum are calculated for different kinetic energies; a validity bound on the classical simulation of electron transport is derived. In order to satisfy the Heisenberg uncertainty principle, uncertainties of 5% must be assigned to position and momentum for 1 keV electrons in water; at 100 eV, these uncertainties are 17 to 20% and are even larger at lower energies. In gaseous media such as air, these uncertainties are much smaller (less than 1% for electrons with energy 20 eV or greater). The classical Monte Carlo transport treatment is questionable for sub-1 keV electrons in condensed water as uncertainties on position and momentum must be large (relative to electron momentum and mean free path) to satisfy the quantum uncertainty principle. Simulations which do not account for these uncertainties are not faithful representations of the physical processes, calling into question the results of MC track structure codes simulating sub-1 keV electron transport. Further, the large difference in the scale at which quantum effects are important in gaseous and condensed media suggests that track structure measurements in gases are not necessarily representative of track structure in condensed materials on a micrometer or a nanometer scale.

Uncertainty and stress: Why it causes diseases and how it is mastered by the brain.

PubMed

Peters, Achim; McEwen, Bruce S; Friston, Karl

2017-09-01

The term 'stress' - coined in 1936 - has many definitions, but until now has lacked a theoretical foundation. Here we present an information-theoretic approach - based on the 'free energy principle' - defining the essence of stress; namely, uncertainty. We address three questions: What is uncertainty? What does it do to us? What are our resources to master it? Mathematically speaking, uncertainty is entropy or 'expected surprise'. The 'free energy principle' rests upon the fact that self-organizing biological agents resist a tendency to disorder and must therefore minimize the entropy of their sensory states. Applied to our everyday life, this means that we feel uncertain, when we anticipate that outcomes will turn out to be something other than expected - and that we are unable to avoid surprise. As all cognitive systems strive to reduce their uncertainty about future outcomes, they face a critical constraint: Reducing uncertainty requires cerebral energy. The characteristic of the vertebrate brain to prioritize its own high energy is captured by the notion of the 'selfish brain'. Accordingly, in times of uncertainty, the selfish brain demands extra energy from the body. If, despite all this, the brain cannot reduce uncertainty, a persistent cerebral energy crisis may develop, burdening the individual by 'allostatic load' that contributes to systemic and brain malfunction (impaired memory, atherogenesis, diabetes and subsequent cardio- and cerebrovascular events). Based on the basic tenet that stress originates from uncertainty, we discuss the strategies our brain uses to avoid surprise and thereby resolve uncertainty. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Risk analysis under uncertainty, the precautionary principle, and the new EU chemicals strategy.

PubMed

Rogers, Michael D

2003-06-01

Three categories of uncertainty in relation to risk assessment are defined; uncertainty in effect, uncertainty in cause, and uncertainty in the relationship between a hypothesised cause and effect. The Precautionary Principle (PP) relates to the third type of uncertainty. Three broad descriptions of the PP are set out, uncertainty justifies action, uncertainty requires action, and uncertainty requires a reversal of the burden of proof for risk assessments. The application of the PP is controversial but what matters in practise is the precautionary action (PA) that follows. The criteria by which the PAs should be judged are detailed. This framework for risk assessment and management under uncertainty is then applied to the envisaged European system for the regulation of chemicals. A new EU regulatory system has been proposed which shifts the burden of proof concerning risk assessments from the regulator to the producer, and embodies the PP in all three of its main regulatory stages. The proposals are critically discussed in relation to three chemicals, namely, atrazine (an endocrine disrupter), cadmium (toxic and possibly carcinogenic), and hydrogen fluoride (a toxic, high-production-volume chemical). Reversing the burden of proof will speed up the regulatory process but the examples demonstrate that applying the PP appropriately, and balancing the countervailing risks and the socio-economic benefits, will continue to be a difficult task for the regulator. The paper concludes with a discussion of the role of precaution in the management of change and of the importance of trust in the effective regulation of uncertain risks.

Entropic Uncertainty Relation and Information Exclusion Relation for multiple measurements in the presence of quantum memory

PubMed Central

Zhang, Jun; Zhang, Yang; Yu, Chang-shui

2015-01-01

The Heisenberg uncertainty principle shows that no one can specify the values of the non-commuting canonically conjugated variables simultaneously. However, the uncertainty relation is usually applied to two incompatible measurements. We present tighter bounds on both entropic uncertainty relation and information exclusion relation for multiple measurements in the presence of quantum memory. As applications, three incompatible measurements on Werner state and Horodecki’s bound entangled state are investigated in details. PMID:26118488

Defense Resource Planning Under Uncertainty: An Application of Robust Decision Making to Munitions Mix Planning

DTIC Science & Technology

2016-02-01

In addition , the parser updates some parameters based on uncertainties. For example, Analytica was very slow to update Pk values based on...moderate range. The additional security environments helped to fill gaps in lower severity. Weapons Effectiveness Pk values were modified to account for two...project is to help improve the value and character of defense resource planning in an era of growing uncertainty and complex strategic challenges

Density functional theory calculations of III-N based semiconductors with mBJLDA

NASA Astrophysics Data System (ADS)

Gürel, Hikmet Hakan; Akıncı, Özden; Ünlü, Hilmi

2017-02-01

In this work, we present first principles calculations based on a full potential linear augmented plane-wave method (FP-LAPW) to calculate structural and electronic properties of III-V based nitrides such as GaN, AlN, InN in a zinc-blende cubic structure. First principles calculation using the local density approximation (LDA) and generalized gradient approximation (GGA) underestimate the band gap. We proposed a new potential called modified Becke-Johnson local density approximation (MBJLDA) that combines modified Becke-Johnson exchange potential and the LDA correlation potential to get better band gap results compared to experiment. We compared various exchange-correlation potentials (LSDA, GGA, HSE, and MBJLDA) to determine band gaps and structural properties of semiconductors. We show that using MBJLDA density potential gives a better agreement with experimental data for band gaps III-V nitrides based semiconductors.

Doctrine Development Process in the Kenya Army: Bridging the Gap

DTIC Science & Technology

2014-06-13

concepts, and principles . It must broadly follow three doctrine development phases: the collection/information gathering phase; the formulation and...a capable lead organization. The organization must eliminate terminological and utility confusion among doctrine, concepts, and principles . It must...15 The relationship Between Military Doctrine, Concept and Principle

The statistical fluctuation study of quantum key distribution in means of uncertainty principle

NASA Astrophysics Data System (ADS)

Liu, Dunwei; An, Huiyao; Zhang, Xiaoyu; Shi, Xuemei

2018-03-01

Laser defects in emitting single photon, photon signal attenuation and propagation of error cause our serious headaches in practical long-distance quantum key distribution (QKD) experiment for a long time. In this paper, we study the uncertainty principle in metrology and use this tool to analyze the statistical fluctuation of the number of received single photons, the yield of single photons and quantum bit error rate (QBER). After that we calculate the error between measured value and real value of every parameter, and concern the propagation error among all the measure values. We paraphrase the Gottesman-Lo-Lutkenhaus-Preskill (GLLP) formula in consideration of those parameters and generate the QKD simulation result. In this study, with the increase in coding photon length, the safe distribution distance is longer and longer. When the coding photon's length is N = 10^{11}, the safe distribution distance can be almost 118 km. It gives a lower bound of safe transmission distance than without uncertainty principle's 127 km. So our study is in line with established theory, but we make it more realistic.

Stability of direct band gap under mechanical strains for monolayer MoS2, MoSe2, WS2 and WSe2

NASA Astrophysics Data System (ADS)

Deng, Shuo; Li, Lijie; Li, Min

2018-07-01

Single layer transition-metal dichalcogenides materials (MoS2, MoSe2, WS2 and WSe2) are investigated using the first-principles method with the emphasis on their responses to mechanical strains. All these materials display the direct band gap under a certain range of strains from compressive to tensile (stable range). We have found that this stable range is different for these materials. Through studying on their mechanical properties again using the first-principles approach, it is unveiled that this stable strain range is determined by the Young's modulus. More analysis on strains induced electronic band gap properties have also been conducted.

Nanodopant-Induced Band Modulation in AgPbmSbTe2+m-Type Nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yi; Ke, Xuezhi; Chen, Changfeng

2011-01-01

We elucidate the fundamental physics of nanoscale dopants in narrow band-gap thermoelectric nanocomposites XPbmYTe2+m (X=Ag,Na; Y=Sb,Bi) using first-principles calculations. Our re- sults unveil distinct band-structure modulations, most notably a sizable band-gap widening driven by nanodopant-induced lattice strain and a band split-off at the conduction band minimum caused by the spin-orbit interaction of the dopant Sb or Bi atoms. Boltzmann transport calculations demon- strate that these band modulations have significant but competing effects on high-temperature elec- tron transport behavior. These results offer insights for understanding recent experimental findings and suggest principles for optimizing thermoelectric properties of narrow band-gap semiconductors.

BOOK REVIEW: Evaluating the Measurement Uncertainty: Fundamentals and practical guidance

NASA Astrophysics Data System (ADS)

Lira, Ignacio

2003-08-01

Evaluating the Measurement Uncertainty is a book written for anyone who makes and reports measurements. It attempts to fill the gaps in the ISO Guide to the Expression of Uncertainty in Measurement, or the GUM, and does a pretty thorough job. The GUM was written with the intent of being applicable by all metrologists, from the shop floor to the National Metrology Institute laboratory; however, the GUM has often been criticized for its lack of user-friendliness because it is primarily filled with statements, but with little explanation. Evaluating the Measurement Uncertainty gives lots of explanations. It is well written and makes use of many good figures and numerical examples. Also important, this book is written by a metrologist from a National Metrology Institute, and therefore up-to-date ISO rules, style conventions and definitions are correctly used and supported throughout. The author sticks very closely to the GUM in topical theme and with frequent reference, so readers who have not read GUM cover-to-cover may feel as if they are missing something. The first chapter consists of a reprinted lecture by T J Quinn, Director of the Bureau International des Poids et Mesures (BIPM), on the role of metrology in today's world. It is an interesting and informative essay that clearly outlines the importance of metrology in our modern society, and why accurate measurement capability, and by definition uncertainty evaluation, should be so important. Particularly interesting is the section on the need for accuracy rather than simply reproducibility. Evaluating the Measurement Uncertainty then begins at the beginning, with basic concepts and definitions. The third chapter carefully introduces the concept of standard uncertainty and includes many derivations and discussion of probability density functions. The author also touches on Monte Carlo methods, calibration correction quantities, acceptance intervals or guardbanding, and many other interesting cases. The book goes on to treat evaluation of expanded uncertainty, joint treatment of several measurands, least-squares adjustment, curve fitting and more. Chapter 6 is devoted to Bayesian inference. Perhaps one can say that Evaluating the Measurement Uncertainty caters to a wider reader-base than the GUM; however, a mathematical or statistical background is still advantageous. Also, this is not a book with a library of worked overall uncertainty evaluations for various measurements; the feel of the book is rather theoretical. The novice will still have some work to do—but this is a good place to start. I think this book is a fitting companion to the GUM because the text complements the GUM, from fundamental principles to more sophisticated measurement situations, and moreover includes intelligent discussion regarding intent and interpretation. Evaluating the Measurement Uncertainty is detailed, and I think most metrologists will really enjoy the detail and care put into this book. Jennifer Decker

Modelling ecosystem service flows under uncertainty with stochiastic SPAN

USGS Publications Warehouse

Johnson, Gary W.; Snapp, Robert R.; Villa, Ferdinando; Bagstad, Kenneth J.

2012-01-01

Ecosystem service models are increasingly in demand for decision making. However, the data required to run these models are often patchy, missing, outdated, or untrustworthy. Further, communication of data and model uncertainty to decision makers is often either absent or unintuitive. In this work, we introduce a systematic approach to addressing both the data gap and the difficulty in communicating uncertainty through a stochastic adaptation of the Service Path Attribution Networks (SPAN) framework. The SPAN formalism assesses ecosystem services through a set of up to 16 maps, which characterize the services in a study area in terms of flow pathways between ecosystems and human beneficiaries. Although the SPAN algorithms were originally defined deterministically, we present them here in a stochastic framework which combines probabilistic input data with a stochastic transport model in order to generate probabilistic spatial outputs. This enables a novel feature among ecosystem service models: the ability to spatially visualize uncertainty in the model results. The stochastic SPAN model can analyze areas where data limitations are prohibitive for deterministic models. Greater uncertainty in the model inputs (including missing data) should lead to greater uncertainty expressed in the model’s output distributions. By using Bayesian belief networks to fill data gaps and expert-provided trust assignments to augment untrustworthy or outdated information, we can account for uncertainty in input data, producing a model that is still able to run and provide information where strictly deterministic models could not. Taken together, these attributes enable more robust and intuitive modelling of ecosystem services under uncertainty.

Participatory Development Principles and Practice: Reflections of a Western Development Worker.

ERIC Educational Resources Information Center

Keough, Noel

1998-01-01

Principles for participatory community development are as follows: humility and respect; power of local knowledge; democratic practice; diverse ways of knowing; sustainability; reality before theory; uncertainty; relativity of time and efficiency; holistic approach; and decisions rooted in the community. (SK)

The Irrelevance of the Risk-Uncertainty Distinction.

PubMed

Roser, Dominic

2017-10-01

Precautionary Principles are often said to be appropriate for decision-making in contexts of uncertainty such as climate policy. Contexts of uncertainty are contrasted to contexts of risk depending on whether we have probabilities or not. Against this view, I argue that the risk-uncertainty distinction is practically irrelevant. I start by noting that the history of the distinction between risk and uncertainty is more varied than is sometimes assumed. In order to examine the distinction, I unpack the idea of having probabilities, in particular by distinguishing three interpretations of probability: objective, epistemic, and subjective probability. I then claim that if we are concerned with whether we have probabilities at all-regardless of how low their epistemic credentials are-then we almost always have probabilities for policy-making. The reason is that subjective and epistemic probability are the relevant interpretations of probability and we almost always have subjective and epistemic probabilities. In contrast, if we are only concerned with probabilities that have sufficiently high epistemic credentials, then we obviously do not always have probabilities. Climate policy, for example, would then be a case of decision-making under uncertainty. But, so I argue, we should not dismiss probabilities with low epistemic credentials. Rather, when they are the best available probabilities our decision principles should make use of them. And, since they are almost always available, the risk-uncertainty distinction remains irrelevant.

Corrected black hole thermodynamics in Damour-Ruffini’s method with generalized uncertainty principle

NASA Astrophysics Data System (ADS)

Zhou, Shiwei; Chen, Ge-Rui

Recently, some approaches to quantum gravity indicate that a minimal measurable length lp ˜ 10-35 should be considered, a direct implication of the minimal measurable length is the generalized uncertainty principle (GUP). Taking the effect of GUP into account, Hawking radiation of massless scalar particles from a Schwarzschild black hole is investigated by the use of Damour-Ruffini’s method. The original Klein-Gordon equation is modified. It is obtained that the corrected Hawking temperature is related to the energy of emitting particles. Some discussions appear in the last section.

Mind the Gap: Exploring the Underground of the NASA Space Cancer Risk Model

NASA Technical Reports Server (NTRS)

Chappell, L. J.; Elgart, S. R.; Milder, C. M.; Shavers, M. R.; Semones, E. J.; Huff, J. L.

2017-01-01

The REID quantifies the lifetime risk of death from radiation-induced cancer in an exposed astronaut. The NASA Space Cancer Risk (NSCR) 2012 mode incorporates elements from physics, biology, epidemiology, and statistics to generate the REID distribution. The current model quantifies the space radiation environment, radiation quality, and dose-rate effects to estimate a NASA-weighted dose. This weighted dose is mapped to the excess risk of radiation-induced cancer mortality from acute exposures to gamma rays and then transferred to an astronaut population. Finally, the REID is determined by integrating this risk over the individual's lifetime. The calculated upper 95% confidence limit of the REID is used to restrict an astronaut's permissible mission duration (PMD) for a proposed mission. As a statistical quantity characterized by broad, subjective uncertainties, REID estimates for space missions result in wide distributions. Currently, the upper 95% confidence level is over 350% larger than the mean REID value, which can severely limit an astronaut's PMD. The model incorporates inputs from multiple scientific disciplines in the risk estimation process. Physics and particle transport models calculate how radiation moves through space, penetrates spacecraft, and makes its way to the human beings onboard. Epidemiological studies of exposures from atomic bombings, medical treatments, and power plants are used to quantify health risks from acute and chronic low linear energy transfer (LET) ionizing radiation. Biological studies in cellular and animal models using radiation at various LETs and energies inform quality metrics for ions present in space radiation. Statistical methodologies unite these elements, controlling for mathematical and scientific uncertainty and variability. Despite current progress, these research platforms contain knowledge gaps contributing to the large uncertainties still present in the model. The NASA Space Radiation Program Element (SRPE) defines the knowledge gaps that impact our understanding of the cancer risks. These gaps are outlined in NASA's Human Research Roadmap [4], which identifies the research questions and actions recommended for reducing the uncertainty in the current NSCR model and for formulation of future models. The greatest contributors to uncertainty in the current model include radiation quality, dose rate effects, and the transfer of exposure-based risk from other populations to an astronaut population. Future formulations of the risk model may benefit from including other potential sources of uncertainty such as space dosimetry, errors in human epidemiology data, and the impact of microgravity and other spaceflight stressors. Here, we discuss the current capabilities of the NSCR-2012 model and several immediate research needs, highlighting areas expected to have an operational impact on the current model schema. The following subway-style route map outlines the NSCR-2012 model (Green Line), emphasizing the research gaps in the Human Research Roadmap for risk of radiation-induced carcinogenesis (Stops on Dashed Lines). The map diagrams how these research gaps feed specific portions of the model.

Supporting Fisheries Management by Means of Complex Models: Can We Point out Isles of Robustness in a Sea of Uncertainty?

PubMed Central

Gasche, Loïc; Mahévas, Stéphanie; Marchal, Paul

2013-01-01

Ecosystems are usually complex, nonlinear and strongly influenced by poorly known environmental variables. Among these systems, marine ecosystems have high uncertainties: marine populations in general are known to exhibit large levels of natural variability and the intensity of fishing efforts can change rapidly. These uncertainties are a source of risks that threaten the sustainability of both fish populations and fishing fleets targeting them. Appropriate management measures have to be found in order to reduce these risks and decrease sensitivity to uncertainties. Methods have been developed within decision theory that aim at allowing decision making under severe uncertainty. One of these methods is the information-gap decision theory. The info-gap method has started to permeate ecological modelling, with recent applications to conservation. However, these practical applications have so far been restricted to simple models with analytical solutions. Here we implement a deterministic approach based on decision theory in a complex model of the Eastern English Channel. Using the ISIS-Fish modelling platform, we model populations of sole and plaice in this area. We test a wide range of values for ecosystem, fleet and management parameters. From these simulations, we identify management rules controlling fish harvesting that allow reaching management goals recommended by ICES (International Council for the Exploration of the Sea) working groups while providing the highest robustness to uncertainties on ecosystem parameters. PMID:24204873

Supporting fisheries management by means of complex models: can we point out isles of robustness in a sea of uncertainty?

PubMed

Gasche, Loïc; Mahévas, Stéphanie; Marchal, Paul

2013-01-01

Ecosystems are usually complex, nonlinear and strongly influenced by poorly known environmental variables. Among these systems, marine ecosystems have high uncertainties: marine populations in general are known to exhibit large levels of natural variability and the intensity of fishing efforts can change rapidly. These uncertainties are a source of risks that threaten the sustainability of both fish populations and fishing fleets targeting them. Appropriate management measures have to be found in order to reduce these risks and decrease sensitivity to uncertainties. Methods have been developed within decision theory that aim at allowing decision making under severe uncertainty. One of these methods is the information-gap decision theory. The info-gap method has started to permeate ecological modelling, with recent applications to conservation. However, these practical applications have so far been restricted to simple models with analytical solutions. Here we implement a deterministic approach based on decision theory in a complex model of the Eastern English Channel. Using the ISIS-Fish modelling platform, we model populations of sole and plaice in this area. We test a wide range of values for ecosystem, fleet and management parameters. From these simulations, we identify management rules controlling fish harvesting that allow reaching management goals recommended by ICES (International Council for the Exploration of the Sea) working groups while providing the highest robustness to uncertainties on ecosystem parameters.

Uncertainty information in climate data records from Earth observation

NASA Astrophysics Data System (ADS)

Merchant, C. J.

2017-12-01

How to derive and present uncertainty in climate data records (CDRs) has been debated within the European Space Agency Climate Change Initiative, in search of common principles applicable across a range of essential climate variables. Various points of consensus have been reached, including the importance of improving provision of uncertainty information and the benefit of adopting international norms of metrology for language around the distinct concepts of uncertainty and error. Providing an estimate of standard uncertainty per datum (or the means to readily calculate it) emerged as baseline good practice, and should be highly relevant to users of CDRs when the uncertainty in data is variable (the usual case). Given this baseline, the role of quality flags is clarified as being complementary to and not repetitive of uncertainty information. Data with high uncertainty are not poor quality if a valid estimate of the uncertainty is available. For CDRs and their applications, the error correlation properties across spatio-temporal scales present important challenges that are not fully solved. Error effects that are negligible in the uncertainty of a single pixel may dominate uncertainty in the large-scale and long-term. A further principle is that uncertainty estimates should themselves be validated. The concepts of estimating and propagating uncertainty are generally acknowledged in geophysical sciences, but less widely practised in Earth observation and development of CDRs. Uncertainty in a CDR depends in part (and usually significantly) on the error covariance of the radiances and auxiliary data used in the retrieval. Typically, error covariance information is not available in the fundamental CDR (FCDR) (i.e., with the level-1 radiances), since provision of adequate level-1 uncertainty information is not yet standard practice. Those deriving CDRs thus cannot propagate the radiance uncertainty to their geophysical products. The FIDUCEO project (www.fiduceo.eu) is demonstrating metrologically sound methodologies addressing this problem for four key historical CDRs. FIDUCEO methods of uncertainty analysis (which also tend to lead to improved FCDRs and CDRs) could support coherent treatment of uncertainty across FCDRs to CDRs and higher level products for a wide range of essential climate variables.

Practical Doping Principles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zunger, A.

2003-05-01

'Theoretical investigations of doping of several wide-gap materials suggest a number of rather general, practical"doping principles" that may help guide experimental strategies of overcoming doping bottlenecks. This paper will be published as a journal article in the future.

Generalized uncertainty principle and quantum gravity phenomenology

NASA Astrophysics Data System (ADS)

Bosso, Pasquale

The fundamental physical description of Nature is based on two mutually incompatible theories: Quantum Mechanics and General Relativity. Their unification in a theory of Quantum Gravity (QG) remains one of the main challenges of theoretical physics. Quantum Gravity Phenomenology (QGP) studies QG effects in low-energy systems. The basis of one such phenomenological model is the Generalized Uncertainty Principle (GUP), which is a modified Heisenberg uncertainty relation and predicts a deformed canonical commutator. In this thesis, we compute Planck-scale corrections to angular momentum eigenvalues, the hydrogen atom spectrum, the Stern-Gerlach experiment, and the Clebsch-Gordan coefficients. We then rigorously analyze the GUP-perturbed harmonic oscillator and study new coherent and squeezed states. Furthermore, we introduce a scheme for increasing the sensitivity of optomechanical experiments for testing QG effects. Finally, we suggest future projects that may potentially test QG effects in the laboratory.

Method for measuring target rotation angle by theodolites

NASA Astrophysics Data System (ADS)

Sun, Zelin; Wang, Zhao; Zhai, Huanchun; Yang, Xiaoxu

2013-05-01

To overcome the disadvantage of the current measurement methods using theodolites in an environment with shock and long working hours and so on, this paper proposes a new method for 3D coordinate measurement that is based on an immovable measuring coordinate system. According to the measuring principle, the mathematics model is established and the measurement uncertainty is analysed. The measurement uncertainty of the new method is a function of the theodolite observation angles and their uncertainty, and can be reduced by optimizing the theodolites’ placement. Compared to other methods, this method allows the theodolite positions to be changed in the measuring process, and mutual collimation between the theodolites is not required. The experimental results show that the measurement model and the optimal placement principle are correct, and the measurement error is less than 0.01° after optimizing the theodolites’ placement.

Continuous quantum measurements and the action uncertainty principle

NASA Astrophysics Data System (ADS)

Mensky, Michael B.

1992-09-01

The path-integral approach to quantum theory of continuous measurements has been developed in preceding works of the author. According to this approach the measurement amplitude determining probabilities of different outputs of the measurement can be evaluated in the form of a restricted path integral (a path integral “in finite limits”). With the help of the measurement amplitude, maximum deviation of measurement outputs from the classical one can be easily determined. The aim of the present paper is to express this variance in a simpler and transparent form of a specific uncertainty principle (called the action uncertainty principle, AUP). The most simple (but weak) form of AUP is δ S≳ℏ, where S is the action functional. It can be applied for simple derivation of the Bohr-Rosenfeld inequality for measurability of gravitational field. A stronger (and having wider application) form of AUP (for ideal measurements performed in the quantum regime) is |∫{/' t″ }(δ S[ q]/δ q( t))Δ q( t) dt|≃ℏ, where the paths [ q] and [Δ q] stand correspondingly for the measurement output and for the measurement error. It can also be presented in symbolic form as Δ(Equation) Δ(Path) ≃ ℏ. This means that deviation of the observed (measured) motion from that obeying the classical equation of motion is reciprocally proportional to the uncertainty in a path (the latter uncertainty resulting from the measurement error). The consequence of AUP is that improving the measurement precision beyond the threshold of the quantum regime leads to decreasing information resulting from the measurement.

Upper Secondary Chemistry Students in a Pharmacochemistry Research Community

NASA Astrophysics Data System (ADS)

van Rens, Lisette; van Muijlwijk, Jacqueline; Beishuizen, Jos; van der Schee, Joop

2013-04-01

This study deals with the participation of 10 upper secondary chemistry students, aged 16-17, and their chemistry teacher in a pharmacochemistry research community on anti-allergy medicines at VU University, Amsterdam, The Netherlands. Participation of students in scientific research raises the question of how to bridge the gap between an upper secondary school inquiry practice and a scientific research practice. To bridge this gap, a design based on 6 principles derived from an educational model of a community of learners was proposed. The study first aimed at revealing whether the proposed principles were necessary according to the students, their teacher and three pharmacochemistry researchers for successful participation of the students in the research community. Second, the study examined whether the students' understanding of discipline-specific content knowledge, interest in scientific research and knowledge about the nature of science changed during the course of the study. Data were obtained from questionnaires, interviews and video tapes. The results indicated that according to the teacher all 6 principles were necessary to bridge the gap, whereas according to the students 1 principle and according to the pharmacochemistry researchers 2 principles were necessary but difficult to achieve. Furthermore, all students gained discipline-specific content knowledge. Their interest in scientific research exhibited a positive change and their knowledge about the nature of science increased. The implications for further research and practice are discussed.

Uncertainty quantification in application of the enrichment meter principle for nondestructive assay of special nuclear material

DOE PAGES

Burr, Tom; Croft, Stephen; Jarman, Kenneth D.

2015-09-05

The various methods of nondestructive assay (NDA) of special nuclear material (SNM) have applications in nuclear nonproliferation, including detection and identification of illicit SNM at border crossings, and quantifying SNM at nuclear facilities for safeguards. No assay method is complete without “error bars,” which provide one way of expressing confidence in the assay result. Consequently, NDA specialists typically quantify total uncertainty in terms of “random” and “systematic” components, and then specify error bars for the total mass estimate in multiple items. Uncertainty quantification (UQ) for NDA has always been important, but it is recognized that greater rigor is needed andmore » achievable using modern statistical methods. To this end, we describe the extent to which the guideline for expressing uncertainty in measurements (GUM) can be used for NDA. Also, we propose improvements over GUM for NDA by illustrating UQ challenges that it does not address, including calibration with errors in predictors, model error, and item-specific biases. A case study is presented using low-resolution NaI spectra and applying the enrichment meter principle to estimate the U-235 mass in an item. The case study illustrates how to update the current American Society for Testing and Materials guide for application of the enrichment meter principle using gamma spectra from a NaI detector.« less

First-principles study of direct and narrow band gap semiconducting β -CuGaO 2

DOE PAGES

Nguyen, Manh Cuong; Zhao, Xin; Wang, Cai-Zhuang; ...

2015-04-16

Semiconducting oxides have attracted much attention due to their great stability in air or water and the abundance of oxygen. Recent success in synthesizing a metastable phase of CuGaO 2 with direct narrow band gap opens up new applications of semiconducting oxides as absorber layer for photovoltaics. Using first-principles density functional theory calculations, we investigate the thermodynamic and mechanical stabilities as well as the structural and electronic properties of the β-CuGaO 2 phase. Our calculations show that the β-CuGaO 2 structure is dynamically and mechanically stable. The energy band gap is confirmed to be direct at the Γ point ofmore » Brillouin zone. In conclusion, the optical absorption occurs right at the band gap edge and the density of states near the valance band maximum is large, inducing an intense absorption of light as observed in experiment.« less

Understanding and applying principles of social cognition and decision making in adaptive environmental governance

EPA Science Inventory

Environmental governance systems are under greater pressure to adapt and to cope with increased social and ecological uncertainty from stressors like climate change. We review principles of social cognition and decision making that shape and constrain how environmental governance...

Consensus building for interlaboratory studies, key comparisons, and meta-analysis

NASA Astrophysics Data System (ADS)

Koepke, Amanda; Lafarge, Thomas; Possolo, Antonio; Toman, Blaza

2017-06-01

Interlaboratory studies in measurement science, including key comparisons, and meta-analyses in several fields, including medicine, serve to intercompare measurement results obtained independently, and typically produce a consensus value for the common measurand that blends the values measured by the participants. Since interlaboratory studies and meta-analyses reveal and quantify differences between measured values, regardless of the underlying causes for such differences, they also provide so-called ‘top-down’ evaluations of measurement uncertainty. Measured values are often substantially over-dispersed by comparison with their individual, stated uncertainties, thus suggesting the existence of yet unrecognized sources of uncertainty (dark uncertainty). We contrast two different approaches to take dark uncertainty into account both in the computation of consensus values and in the evaluation of the associated uncertainty, which have traditionally been preferred by different scientific communities. One inflates the stated uncertainties by a multiplicative factor. The other adds laboratory-specific ‘effects’ to the value of the measurand. After distinguishing what we call recipe-based and model-based approaches to data reductions in interlaboratory studies, we state six guiding principles that should inform such reductions. These principles favor model-based approaches that expose and facilitate the critical assessment of validating assumptions, and give preeminence to substantive criteria to determine which measurement results to include, and which to exclude, as opposed to purely statistical considerations, and also how to weigh them. Following an overview of maximum likelihood methods, three general purpose procedures for data reduction are described in detail, including explanations of how the consensus value and degrees of equivalence are computed, and the associated uncertainty evaluated: the DerSimonian-Laird procedure; a hierarchical Bayesian procedure; and the Linear Pool. These three procedures have been implemented and made widely accessible in a Web-based application (NIST Consensus Builder). We illustrate principles, statistical models, and data reduction procedures in four examples: (i) the measurement of the Newtonian constant of gravitation; (ii) the measurement of the half-lives of radioactive isotopes of caesium and strontium; (iii) the comparison of two alternative treatments for carotid artery stenosis; and (iv) a key comparison where the measurand was the calibration factor of a radio-frequency power sensor.

First-principles study of direct and indirect optical absorption in BaSnO3

NASA Astrophysics Data System (ADS)

Kang, Youngho; Peelaers, Hartwin; Krishnaswamy, Karthik; Van de Walle, Chris G.

2018-02-01

We report first-principles results for the electronic structure and the optical absorption of perovskite BaSnO3 (BSO). BSO has an indirect fundamental gap, and hence, both direct and indirect transitions need to be examined. We assess direct absorption by calculations of the dipole matrix elements. The phonon-assisted indirect absorption spectrum at room temperature is calculated using a quasiclassical approach. Our analysis provides important insights into the optical properties of BSO and addresses several inconsistencies in the results of optical absorption experiments. We shed light on the variety of bandgap values that have been previously reported, concluding that the indirect gap is 2.98 eV and the direct gap is 3.46 eV.

Multi-Case Review of the Application of the Precautionary Principle in European Union Law and Case Law.

PubMed

Garnett, Kenisha; Parsons, David J

2017-03-01

The precautionary principle was formulated to provide a basis for political action to protect the environment from potentially severe or irreversible harm in circumstances of scientific uncertainty that prevent a full risk or cost-benefit analysis. It underpins environmental law in the European Union and has been extended to include public health and consumer safety. The aim of this study was to examine how the precautionary principle has been interpreted and subsequently applied in practice, whether these applications were consistent, and whether they followed the guidance from the Commission. A review of the literature was used to develop a framework for analysis, based on three attributes: severity of potential harm, standard of evidence (or degree of uncertainty), and nature of the regulatory action. This was used to examine 15 pieces of legislation or judicial decisions. The decision whether or not to apply the precautionary principle appears to be poorly defined, with ambiguities inherent in determining what level of uncertainty and significance of hazard justifies invoking it. The cases reviewed suggest that the Commission's guidance was not followed consistently in forming legislation, although judicial decisions tended to be more consistent and to follow the guidance by requiring plausible evidence of potential hazard in order to invoke precaution. © 2016 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

Quantum nondemolition measurements - Comment on recent developments. [detectability of extremely weak signals

NASA Technical Reports Server (NTRS)

Von Roos, O.

1978-01-01

The limitations of the detectability of extremely weak signals (gravitational radiation for instance) imposed by Heisenberg's uncertainty principle on the sequential determination of those signals have been explored recently. A variety of schemes have been proposed to circumvent these limitations. Although all of the earlier attempts have been proven fruitless a recent proposal seems to be quite promising. The scheme, consisting of two harmonic oscillators interacting with each other in a peculiar way, allows for an exact analytical solution which is derived here. If it can be assumed that the expectation value of one of the canonical variables of the total system suffices to monitor the weak signal it can be shown that, in the absence of thermal noise, arbitrarily weak signals can in principle be measured without interference from the uncertainty principle.

Capturing total chronological and spatial uncertainties in palaeo-ice sheet reconstructions: the DATED example

NASA Astrophysics Data System (ADS)

Hughes, Anna; Gyllencreutz, Richard; Mangerud, Jan; Svendsen, John Inge

2017-04-01

Glacial geologists generate empirical reconstructions of former ice-sheet dynamics by combining evidence from the preserved record of glacial landforms (e.g. end moraines, lineations) and sediments with chronological evidence (mainly numerical dates derived predominantly from radiocarbon, exposure and luminescence techniques). However the geomorphological and sedimentological footprints and chronological data are both incomplete records in both space and time, and all have multiple types of uncertainty associated with them. To understand ice sheets' response to climate we need numerical models of ice-sheet dynamics based on physical principles. To test and/or constrain such models, empirical reconstructions of past ice sheets that capture and acknowledge all uncertainties are required. In 2005 we started a project (Database of the Eurasian Deglaciation, DATED) to produce an empirical reconstruction of the evolution of the last Eurasian ice sheets, (including the British-Irish, Scandinavian and Svalbard-Barents-Kara Seas ice sheets) that is fully documented, specified in time, and includes uncertainty estimates. Over 5000 dates relevant to constraining ice build-up and retreat were assessed for reliability and used together with published ice-sheet margin positions based on glacial geomorphology to reconstruct time-slice maps of the ice sheets' extent. The DATED maps show synchronous ice margins with maximum-minimum uncertainty bounds for every 1000 years between 25-10 kyr ago. In the first version of results (DATED-1; Hughes et al. 2016) all uncertainties (both quantitative and qualitative, e.g. precision and accuracy of numerical dates, correlation of moraines, stratigraphic interpretations) were combined based on our best glaciological-geological assessment and expressed in terms of distance as a 'fuzzy' margin. Large uncertainties (>100 km) exist; predominantly across marine sectors and other locations where there are spatial gaps in the dating record (e.g. the timing of coalescence and separation of the Scandinavian and Svalbard-Barents-Kara ice sheets) but also in well-studied areas due to conflicting yet apparently equally robust data. In the four years since the DATED-1 census (1 January 2013), the volume of new information (from both dates and mapped glacial geomorphology) has grown significantly ( 1000 new dates). Here, we present work towards the updated version of results, DATED-2, that attempts to further reduce and explicitly report all uncertainties inherent in ice sheet reconstructions. Hughes, A. L. C., Gyllencreutz, R., Lohne, Ø. S., Mangerud, J., Svendsen, J. I. 2016: The last Eurasian ice sheets - a chronological database and time-slice reconstruction, DATED-1. Boreas, 45, 1-45. 10.1111/bor.12142

On the Minimal Length Uncertainty Relation and the Foundations of String Theory

DOE PAGES

Chang, Lay Nam; Lewis, Zachary; Minic, Djordje; ...

2011-01-01

We review our work on the minimal length uncertainty relation as suggested by perturbative string theory. We discuss simple phenomenological implications of the minimal length uncertainty relation and then argue that the combination of the principles of quantum theory and general relativity allow for a dynamical energy-momentum space. We discuss the implication of this for the problem of vacuum energy and the foundations of nonperturbative string theory.

Production of photocurrent due to intermediate-to-conduction-band transitions: a demonstration of a key operating principle of the intermediate-band solar cell.

PubMed

Martí, A; Antolín, E; Stanley, C R; Farmer, C D; López, N; Díaz, P; Cánovas, E; Linares, P G; Luque, A

2006-12-15

We present intermediate-band solar cells manufactured using quantum dot technology that show for the first time the production of photocurrent when two sub-band-gap energy photons are absorbed simultaneously. One photon produces an optical transition from the intermediate-band to the conduction band while the second pumps an electron from the valence band to the intermediate-band. The detection of this two-photon absorption process is essential to verify the principles of operation of the intermediate-band solar cell. The phenomenon is the cornerstone physical principle that ultimately allows the production of photocurrent in a solar cell by below band gap photon absorption, without degradation of its output voltage.

DCS: A Case Study of Identification of Knowledge and Disposition Gaps Using Principles of Continuous Risk Management

NASA Technical Reports Server (NTRS)

Norcross, Jason; Steinberg, Susan; Kundrot, Craig; Charles, John

2011-01-01

The Human Research Program (HRP) is formulated around the program architecture of Evidence-Risk-Gap-Task-Deliverable. Review of accumulated evidence forms the basis for identification of high priority risks to human health and performance in space exploration. Gaps in knowledge or disposition are identified for each risk, and a portfolio of research tasks is developed to fill them. Deliverables from the tasks inform the evidence base with the ultimate goal of defining the level of risk and reducing it to an acceptable level. A comprehensive framework for gap identification, focus, and metrics has been developed based on principles of continuous risk management and clinical care. Research towards knowledge gaps improves understanding of the likelihood, consequence or timeframe of the risk. Disposition gaps include development of standards or requirements for risk acceptance, development of countermeasures or technology to mitigate the risk, and yearly technology assessment related to watching developments related to the risk. Standard concepts from clinical care: prevention, diagnosis, treatment, monitoring, rehabilitation, and surveillance, can be used to focus gaps dealing with risk mitigation. The research plan for the new HRP Risk of Decompression Sickness (DCS) used the framework to identify one disposition gap related to establishment of a DCS standard for acceptable risk, two knowledge gaps related to DCS phenomenon and mission attributes, and three mitigation gaps focused on prediction, prevention, and new technology watch. These gaps were organized in this manner primarily based on target for closure and ease of organizing interim metrics so that gap status could be quantified. Additional considerations for the knowledge gaps were that one was highly design reference mission specific and the other gap was focused on DCS phenomenon.

Insights into water managers' perception and handling of uncertainties - a study of the role of uncertainty in practitioners' planning and decision-making

NASA Astrophysics Data System (ADS)

Höllermann, Britta; Evers, Mariele

2017-04-01

Planning and decision-making under uncertainty is common in water management due to climate variability, simplified models, societal developments, planning restrictions just to name a few. Dealing with uncertainty can be approached from two sites, hereby affecting the process and form of communication: Either improve the knowledge base by reducing uncertainties or apply risk-based approaches to acknowledge uncertainties throughout the management process. Current understanding is that science more strongly focusses on the former approach, while policy and practice are more actively applying a risk-based approach to handle incomplete and/or ambiguous information. The focus of this study is on how water managers perceive and handle uncertainties at the knowledge/decision interface in their daily planning and decision-making routines. How they evaluate the role of uncertainties for their decisions and how they integrate this information into the decision-making process. Expert interviews and questionnaires among practitioners and scientists provided an insight into their perspectives on uncertainty handling allowing a comparison of diverse strategies between science and practice as well as between different types of practitioners. Our results confirmed the practitioners' bottom up approach from potential measures upwards instead of impact assessment downwards common in science-based approaches. This science-practice gap may hinder effective uncertainty integration and acknowledgement in final decisions. Additionally, the implementation of an adaptive and flexible management approach acknowledging uncertainties is often stalled by rigid regulations favouring a predict-and-control attitude. However, the study showed that practitioners' level of uncertainty recognition varies with respect to his or her affiliation to type of employer and business unit, hence, affecting the degree of the science-practice-gap with respect to uncertainty recognition. The level of working experience was examined as a cross-cutting property of science and practice with increasing levels of uncertainty awareness and integration among more experienced researchers and practitioners. In conclusion, our study of water managers' perception and handling of uncertainties provides valuable insights for finding routines for uncertainty communication and integration into planning and decision-making processes by acknowledging the divers perceptions among producers, users and receivers of uncertainty information. These results can contribute to more effective integration of hydrological forecast and improved decisions.

Uncertainty quantification metrics for whole product life cycle cost estimates in aerospace innovation

NASA Astrophysics Data System (ADS)

Schwabe, O.; Shehab, E.; Erkoyuncu, J.

2015-08-01

The lack of defensible methods for quantifying cost estimate uncertainty over the whole product life cycle of aerospace innovations such as propulsion systems or airframes poses a significant challenge to the creation of accurate and defensible cost estimates. Based on the axiomatic definition of uncertainty as the actual prediction error of the cost estimate, this paper provides a comprehensive overview of metrics used for the uncertainty quantification of cost estimates based on a literature review, an evaluation of publicly funded projects such as part of the CORDIS or Horizon 2020 programs, and an analysis of established approaches used by organizations such NASA, the U.S. Department of Defence, the ESA, and various commercial companies. The metrics are categorized based on their foundational character (foundations), their use in practice (state-of-practice), their availability for practice (state-of-art) and those suggested for future exploration (state-of-future). Insights gained were that a variety of uncertainty quantification metrics exist whose suitability depends on the volatility of available relevant information, as defined by technical and cost readiness level, and the number of whole product life cycle phases the estimate is intended to be valid for. Information volatility and number of whole product life cycle phases can hereby be considered as defining multi-dimensional probability fields admitting various uncertainty quantification metric families with identifiable thresholds for transitioning between them. The key research gaps identified were the lacking guidance grounded in theory for the selection of uncertainty quantification metrics and lacking practical alternatives to metrics based on the Central Limit Theorem. An innovative uncertainty quantification framework consisting of; a set-theory based typology, a data library, a classification system, and a corresponding input-output model are put forward to address this research gap as the basis for future work in this field.

Generalized uncertainty principle impact onto the black holes information flux and the sparsity of Hawking radiation

NASA Astrophysics Data System (ADS)

Alonso-Serrano, Ana; DÄ browski, Mariusz P.; Gohar, Hussain

2018-02-01

We investigate the generalized uncertainty principle (GUP) corrections to the entropy content and the information flux of black holes, as well as the corrections to the sparsity of the Hawking radiation at the late stages of evaporation. We find that due to these quantum gravity motivated corrections, the entropy flow per particle reduces its value on the approach to the Planck scale due to a better accuracy in counting the number of microstates. We also show that the radiation flow is no longer sparse when the mass of a black hole approaches Planck mass which is not the case for non-GUP calculations.

Aiding alternatives assessment with an uncertainty-tolerant hazard scoring method.

PubMed

Faludi, Jeremy; Hoang, Tina; Gorman, Patrick; Mulvihill, Martin

2016-11-01

This research developed a single-score system to simplify and clarify decision-making in chemical alternatives assessment, accounting for uncertainty. Today, assessing alternatives to hazardous constituent chemicals is a difficult task-rather than comparing alternatives by a single definitive score, many independent toxicological variables must be considered at once, and data gaps are rampant. Thus, most hazard assessments are only comprehensible to toxicologists, but business leaders and politicians need simple scores to make decisions. In addition, they must balance hazard against other considerations, such as product functionality, and they must be aware of the high degrees of uncertainty in chemical hazard data. This research proposes a transparent, reproducible method to translate eighteen hazard endpoints into a simple numeric score with quantified uncertainty, alongside a similar product functionality score, to aid decisions between alternative products. The scoring method uses Clean Production Action's GreenScreen as a guide, but with a different method of score aggregation. It provides finer differentiation between scores than GreenScreen's four-point scale, and it displays uncertainty quantitatively in the final score. Displaying uncertainty also illustrates which alternatives are early in product development versus well-defined commercial products. This paper tested the proposed assessment method through a case study in the building industry, assessing alternatives to spray polyurethane foam insulation containing methylene diphenyl diisocyanate (MDI). The new hazard scoring method successfully identified trade-offs between different alternatives, showing finer resolution than GreenScreen Benchmarking. Sensitivity analysis showed that different weighting schemes in hazard scores had almost no effect on alternatives ranking, compared to uncertainty from data gaps. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimism in the face of uncertainty supported by a statistically-designed multi-armed bandit algorithm.

PubMed

Kamiura, Moto; Sano, Kohei

2017-10-01

The principle of optimism in the face of uncertainty is known as a heuristic in sequential decision-making problems. Overtaking method based on this principle is an effective algorithm to solve multi-armed bandit problems. It was defined by a set of some heuristic patterns of the formulation in the previous study. The objective of the present paper is to redefine the value functions of Overtaking method and to unify the formulation of them. The unified Overtaking method is associated with upper bounds of confidence intervals of expected rewards on statistics. The unification of the formulation enhances the universality of Overtaking method. Consequently we newly obtain Overtaking method for the exponentially distributed rewards, numerically analyze it, and show that it outperforms UCB algorithm on average. The present study suggests that the principle of optimism in the face of uncertainty should be regarded as the statistics-based consequence of the law of large numbers for the sample mean of rewards and estimation of upper bounds of expected rewards, rather than as a heuristic, in the context of multi-armed bandit problems. Copyright © 2017 Elsevier B.V. All rights reserved.

Plasmonic trace sensing below the photon shot noise limit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pooser, Raphael C.; Lawrie, Benjamin J.

Plasmonic sensors are important detectors of biochemical trace compounds, but those that utilize optical readout are approaching their absolute limits of detection as defined by the Heisenberg uncertainty principle in both differential intensity and phase readout. However, the use of more general minimum uncertainty states in the form of squeezed light can push the noise floor in these sensors below the shot noise limit (SNL) in one analysis variable at the expense of another. Here, we demonstrate a quantum plasmonic sensor whose noise floor is reduced below the SNL in order to perform index of refraction measurements with sensitivities unobtainablemore » with classical plasmonic sensors. The increased signal-to-noise ratio can result in faster detection of analyte concentrations that were previously lost in the noise. As a result, these benefits are the hallmarks of a sensor exploiting quantum readout fields in order to manipulate the limits of the Heisenberg uncertainty principle.« less

Plasmonic trace sensing below the photon shot noise limit

DOE PAGES

Pooser, Raphael C.; Lawrie, Benjamin J.

2015-12-09

Plasmonic sensors are important detectors of biochemical trace compounds, but those that utilize optical readout are approaching their absolute limits of detection as defined by the Heisenberg uncertainty principle in both differential intensity and phase readout. However, the use of more general minimum uncertainty states in the form of squeezed light can push the noise floor in these sensors below the shot noise limit (SNL) in one analysis variable at the expense of another. Here, we demonstrate a quantum plasmonic sensor whose noise floor is reduced below the SNL in order to perform index of refraction measurements with sensitivities unobtainablemore » with classical plasmonic sensors. The increased signal-to-noise ratio can result in faster detection of analyte concentrations that were previously lost in the noise. As a result, these benefits are the hallmarks of a sensor exploiting quantum readout fields in order to manipulate the limits of the Heisenberg uncertainty principle.« less

Reconstructing signals from noisy data with unknown signal and noise covariance.

PubMed

Oppermann, Niels; Robbers, Georg; Ensslin, Torsten A

2011-10-01

We derive a method to reconstruct Gaussian signals from linear measurements with Gaussian noise. This new algorithm is intended for applications in astrophysics and other sciences. The starting point of our considerations is the principle of minimum Gibbs free energy, which was previously used to derive a signal reconstruction algorithm handling uncertainties in the signal covariance. We extend this algorithm to simultaneously uncertain noise and signal covariances using the same principles in the derivation. The resulting equations are general enough to be applied in many different contexts. We demonstrate the performance of the algorithm by applying it to specific example situations and compare it to algorithms not allowing for uncertainties in the noise covariance. The results show that the method we suggest performs very well under a variety of circumstances and is indeed qualitatively superior to the other methods in cases where uncertainty in the noise covariance is present.

Making Decisions about an Educational Game, Simulation or Workshop: A 'Game Theory' Perspective.

ERIC Educational Resources Information Center

Cryer, Patricia

1988-01-01

Uses game theory to help practitioners make decisions about educational games, simulations, or workshops whose outcomes depend to some extent on chance. Highlights include principles for making decisions involving risk; elementary laws of probability; utility theory; and principles for making decisions involving uncertainty. (eight references)…

Revealing a quantum feature of dimensionless uncertainty in linear and quadratic potentials by changing potential intervals

NASA Astrophysics Data System (ADS)

Kheiri, R.

2016-09-01

As an undergraduate exercise, in an article (2012 Am. J. Phys. 80 780-14), quantum and classical uncertainties for dimensionless variables of position and momentum were evaluated in three potentials: infinite well, bouncing ball, and harmonic oscillator. While original quantum uncertainty products depend on {{\\hslash }} and the number of states (n), a dimensionless approach makes the comparison between quantum uncertainty and classical dispersion possible by excluding {{\\hslash }}. But the question is whether the uncertainty still remains dependent on quantum number n. In the above-mentioned article, there lies this contrast; on the one hand, the dimensionless quantum uncertainty of the potential box approaches classical dispersion only in the limit of large quantum numbers (n\\to ∞ )—consistent with the correspondence principle. On the other hand, similar evaluations for bouncing ball and harmonic oscillator potentials are equal to their classical counterparts independent of n. This equality may hide the quantum feature of low energy levels. In the current study, we change the potential intervals in order to make them symmetric for the linear potential and non-symmetric for the quadratic potential. As a result, it is shown in this paper that the dimensionless quantum uncertainty of these potentials in the new potential intervals is expressed in terms of quantum number n. In other words, the uncertainty requires the correspondence principle in order to approach the classical limit. Therefore, it can be concluded that the dimensionless analysis, as a useful pedagogical method, does not take away the quantum feature of the n-dependence of quantum uncertainty in general. Moreover, our numerical calculations include the higher powers of the position for the potentials.

Signal enhancement due to high-Z nanofilm electrodes in parallel plate ionization chambers with variable microgaps.

PubMed

Brivio, Davide; Sajo, Erno; Zygmanski, Piotr

2017-12-01

We developed a method for measuring signal enhancement produced by high-Z nanofilm electrodes in parallel plate ionization chambers with variable thickness microgaps. We used a laboratory-made variable gap parallel plate ionization chamber with nanofilm electrodes made of aluminum-aluminum (Al-Al) and aluminum-tantalum (Al-Ta). The electrodes were evaporated on 1 mm thick glass substrates. The interelectrode air gap was varied from 3 μm to 1 cm. The gap size was measured using a digital micrometer and it was confirmed by capacitance measurements. The electric field in the chamber was kept between 0.1 kV/cm and 1 kV/cm for all the gap sizes by applying appropriate compensating voltages. The chamber was exposed to 120 kVp X-rays. The current was measured using a commercial data acquisition system with temporal resolution of 600 Hz. In addition, radiation transport simulations were carried out to characterize the dose, D(x), high-energy electron current, J(x), and deposited charge, Q(x), as a function of distance, x, from the electrodes. A deterministic method was selected over Monte Carlo due to its ability to produce results with 10 nm spatial resolution without stochastic uncertainties. Experimental signal enhancement ratio, SER(G) which we defined as the ratio of signal for Al-air-Ta to signal for Al-air-Al for each gap size, was compared to computations. The individual contributions of dose, electron current, and charge deposition to the signal enhancement were determined. Experimental signals matched computed data for all gap sizes after accounting for several contributions to the signal: (a) charge carrier generated via ionization due to the energy deposited in the air gap, D(x); (b) high-energy electron current, J(x), leaking from high-Z electrode (Ta) toward low-Z electrode (Al); (c) deposited charge in the air gap, Q(x); and (d) the decreased collection efficiency for large gaps (>~500 μm). Q(x) accounts for the electrons below 100 eV, which are regarded as stopped by the radiation transport code but which can move and form electron current in small gaps (<100 μm). While the total energy deposited in the air gap increases with gap size for both samples, the average high-energy current and deposited charge are moderately decreasing with the air gap. When gap sizes are smaller than ~20 μm, the contribution to signal from dose approaches zero while contributions from high-energy current and deposited charges give rise to an offset signal. The measured signal enhancement ratio (SER) was 40.0 ± 5.0 for the 3 μm gap and rapidly decreasing with gap size down to 9.9 ± 1.2 for the 21 μm gap and to 6.6 ± 0.3 for the 100 μm gap. The uncertainties in SER were mostly due to uncertainties in gap size and data acquisition system. We developed an experimental method to determine the signal enhancement due to high-Z nanolayers in parallel plate ionization chambers with micrometer spatial resolution. As the water-equivalent thicknesses of these air gaps are 3 nm to 10 μm, the method may also be applicable for nanoscopic spatial resolution of other gap materials. The method may be extended to solid insulator materials with low Z. © 2017 American Association of Physicists in Medicine.

Comparative Education Research Framed by Neo-Institutional Theory: A Review of Diverse Approaches and Conflicting Assumptions

ERIC Educational Resources Information Center

Wiseman, Alexander W.; Astiz, M. Fernanda; Baker, David P.

2014-01-01

The rise in globalisation studies in comparative education places neo-institutional theory at the centre of many debates among comparative education researchers. However, uncertainty about how to interpret neo-institutional theory still persists among educational comparativists. With this uncertainty comes misinterpretation of its principles,…

Intelligent Information Retrieval: Diagnosing Information Need. Part II. Uncertainty Expansion in a Prototype of a Diagnostic IR Tool.

ERIC Educational Resources Information Center

Cole, Charles; Cantero, Pablo; Sauve, Diane

1998-01-01

Outlines a prototype of an intelligent information-retrieval tool to facilitate information access for an undergraduate seeking information for a term paper. Topics include diagnosing the information need, Kuhlthau's information-search-process model, Shannon's mathematical theory of communication, and principles of uncertainty expansion and…

Role of information theoretic uncertainty relations in quantum theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jizba, Petr, E-mail: p.jizba@fjfi.cvut.cz; ITP, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin; Dunningham, Jacob A., E-mail: J.Dunningham@sussex.ac.uk

2015-04-15

Uncertainty relations based on information theory for both discrete and continuous distribution functions are briefly reviewed. We extend these results to account for (differential) Rényi entropy and its related entropy power. This allows us to find a new class of information-theoretic uncertainty relations (ITURs). The potency of such uncertainty relations in quantum mechanics is illustrated with a simple two-energy-level model where they outperform both the usual Robertson–Schrödinger uncertainty relation and Shannon entropy based uncertainty relation. In the continuous case the ensuing entropy power uncertainty relations are discussed in the context of heavy tailed wave functions and Schrödinger cat states. Again,more » improvement over both the Robertson–Schrödinger uncertainty principle and Shannon ITUR is demonstrated in these cases. Further salient issues such as the proof of a generalized entropy power inequality and a geometric picture of information-theoretic uncertainty relations are also discussed.« less

Precaution or Integrated Responsibility Approach to Nanovaccines in Fish Farming? A Critical Appraisal of the UNESCO Precautionary Principle.

PubMed

Myhr, Anne Ingeborg; Myskja, Bjørn K

2011-04-01

Nanoparticles have multifaceted advantages in drug administration as vaccine delivery and hence hold promises for improving protection of farmed fish against diseases caused by pathogens. However, there are concerns that the benefits associated with distribution of nanoparticles may also be accompanied with risks to the environment and health. The complexity of the natural and social systems involved implies that the information acquired in quantified risk assessments may be inadequate for evidence-based decisions. One controversial strategy for dealing with this kind of uncertainty is the precautionary principle. A few years ago, an UNESCO expert group suggested a new approach for implementation of the principle. Here we compare the UNESCO principle with earlier versions and explore the advantages and disadvantages by employing the UNESCO version to the use of PLGA nanoparticles for delivery of vaccines in aquaculture. Finally, we discuss whether a combined scientific and ethical analysis that involves the concept of responsibility will enable approaches that can provide a supplement to the precautionary principle as basis for decision-making in areas of scientific uncertainty, such as the application of nanoparticles in the vaccination of farmed fish.

Zn(x)Cd(1-x)Se nanomultipods with tunable band gaps: synthesis and first-principles calculations.

PubMed

Wei, Hao; Su, Yanjie; Han, Ziyi; Li, Tongtong; Ren, Xinglong; Yang, Zhi; Wei, Liangming; Cong, Fengsong; Zhang, Yafei

2013-06-14

In this paper, we demonstrate that ZnxCd1-xSe nanomultipods can be synthesized via a facile and nontoxic solution-based method. Interesting aspects of composition, morphology and optical properties were deeply explored. The value of Zn/(Zn+Cd) could be altered across the entire range from 0.08 to 0.86 by varying the ratio of cation precursor contents. The band gap energy could be linearly tuned from 1.88 to 2.48 eV with respect to the value of Zn/(Zn+Cd). The experiment also showed that oleylamine played a dominant role in the formation of multipod structure. A possible growth mechanism was further suggested. First-principles calculations of band gap energy and density of states in the Vienna ab initio simulation package code were performed to verify the experimental variation tendency of the band gap. Computational results indicated that dissimilarities of electronic band structures and orbital constitutions determined the tunable band gap of the as-synthesized nanomultipod, which might be promising for versatile applications in relevant areas of solar cells, biomedicine, sensors, catalysts and so on.

Theoretical investigations on diamondoids (CnHm, n = 10-41): Nomenclature, structural stabilities, and gap distributions

NASA Astrophysics Data System (ADS)

Wang, Ya-Ting; Zhao, Yu-Jun; Liao, Ji-Hai; Yang, Xiao-Bao

2018-01-01

Combining the congruence check and the first-principles calculations, we have systematically investigated the structural stabilities and gap distributions of possible diamondoids (CnHm) with the carbon numbers (n) from 10 to 41. A simple method for the nomenclature is proposed, which can be used to distinguish and screen the candidates with high efficiency. Different from previous theoretical studies, the possible diamondoids can be enumerated according to our nomenclature, without any pre-determination from experiments. The structural stabilities and electronic properties have been studied by density functional based tight binding and first-principles methods, where a nearly linear correlation is found between the energy gaps obtained by these two methods. According to the formation energy of structures, we have determined the stable configurations as a function of chemical potential. The maximum and minimum energy gaps are found to be dominated by the shape of diamondoids for clusters with a given number of carbon atoms, while the gap decreases in general as the size increases due to the quantum confinement.

Propulsion and Power Rapid Response Research and Development (R&D) Support. Delivery Order 0011: Advanced Propulsion Fuels Research and Development-Subtask: Framework and Guidance for Estimating Greenhouse Gas Footprints of Aviation Fuels

DTIC Science & Technology

2009-04-01

Uncertainties, Gaps , and Issues for the Use of GWP to Examine Emissions From Aviation That Impact Global Climate Change. (Wuebbles, Yang and Herman 2008...selecting time periods and spatial scales for data gathering, strategies for filling data gaps , and computational considerations for managing the...Fuels Assumptions, methodological choices, strategies for filling data gaps , and other factors throughout the life cycle substantially influence the

Visible-light absorption and large band-gap bowing of GaN 1-xSb x from first principles

DOE PAGES

Sheetz, R. Michael; Richter, Ernst; Andriotis, Antonis N.; ...

2011-08-01

Applicability of the Ga(Sb x)N 1-x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory incorporating the local density approximation and generalized gradient approximation plus the Hubbard U parameter formalism. Our calculations reveal that a relatively small concentration of Sb impurities is sufficient to achieve a significant narrowing of the band gap, enabling absorption of visible light. Theoretical results predict that Ga(Sb x)N 1-x alloys with 2-eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sb x)N 1-x alloys could be potential candidates for splitting watermore » under visible light irradiation.« less

Fermi Blobs and the Symplectic Camel: A Geometric Picture of Quantum States

NASA Astrophysics Data System (ADS)

Gossona, Maurice A. De

We have explained in previous work the correspondence between the standard squeezed coherent states of quantum mechanics, and quantum blobs, which are the smallest phase space units compatible with the uncertainty principle of quantum mechanics and having the symplectic group as a group of symmetries. In this work, we discuss the relation between quantum blobs and a certain level set (which we call "Fermi blob") introduced by Enrico Fermi in 1930. Fermi blobs allows us to extend our previous results not only to the excited states of the generalized harmonic oscillator in n dimensions, but also to arbitrary quadratic Hamiltonians. As is the case for quantum blobs, we can evaluate Fermi blobs using a topological notion, related to the uncertainty principle, the symplectic capacity of a phase space set. The definition of this notion is made possible by Gromov's symplectic non-squeezing theorem, nicknamed the "principle of the symplectic camel".

Free surfaces recast superconductivity in few-monolayer MgB2: Combined first-principles and ARPES demonstration.

PubMed

Bekaert, J; Bignardi, L; Aperis, A; van Abswoude, P; Mattevi, C; Gorovikov, S; Petaccia, L; Goldoni, A; Partoens, B; Oppeneer, P M; Peeters, F M; Milošević, M V; Rudolf, P; Cepek, C

2017-10-31

Two-dimensional materials are known to harbour properties very different from those of their bulk counterparts. Recent years have seen the rise of atomically thin superconductors, with a caveat that superconductivity is strongly depleted unless enhanced by specific substrates, intercalants or adatoms. Surprisingly, the role in superconductivity of electronic states originating from simple free surfaces of two-dimensional materials has remained elusive to date. Here, based on first-principles calculations, anisotropic Eliashberg theory, and angle-resolved photoemission spectroscopy (ARPES), we show that surface states in few-monolayer MgB 2 make a major contribution to the superconducting gap spectrum and density of states, clearly distinct from the widely known, bulk-like σ- and π-gaps. As a proof of principle, we predict and measure the gap opening on the magnesium-based surface band up to a critical temperature as high as ~30 K for merely six monolayers thick MgB 2 . These findings establish free surfaces as an unavoidable ingredient in understanding and further tailoring of superconductivity in atomically thin materials.

Detection capacity, information gaps and the design of surveillance programs for invasive forest pests

Treesearch

Denys Yemshanov; Frank Koch; Yakov Ben-Haim; William Smith

2010-01-01

Integrated pest risk maps and their underlying assessments provide broad guidance for establishing surveillance programs for invasive species, but they rarely account for knowledge gaps regarding the pest of interest or how these can be reduced. In this study we demonstrate how the somewhat competing notions of robustness to uncertainty and potential knowledge gains...

Lorentz invariance violation and generalized uncertainty principle

NASA Astrophysics Data System (ADS)

Tawfik, Abdel Nasser; Magdy, H.; Ali, A. Farag

2016-01-01

There are several theoretical indications that the quantum gravity approaches may have predictions for a minimal measurable length, and a maximal observable momentum and throughout a generalization for Heisenberg uncertainty principle. The generalized uncertainty principle (GUP) is based on a momentum-dependent modification in the standard dispersion relation which is conjectured to violate the principle of Lorentz invariance. From the resulting Hamiltonian, the velocity and time of flight of relativistic distant particles at Planck energy can be derived. A first comparison is made with recent observations for Hubble parameter in redshift-dependence in early-type galaxies. We find that LIV has two types of contributions to the time of flight delay Δ t comparable with that observations. Although the wrong OPERA measurement on faster-than-light muon neutrino anomaly, Δ t, and the relative change in the speed of muon neutrino Δ v in dependence on redshift z turn to be wrong, we utilize its main features to estimate Δ v. Accordingly, the results could not be interpreted as LIV. A third comparison is made with the ultra high-energy cosmic rays (UHECR). It is found that an essential ingredient of the approach combining string theory, loop quantum gravity, black hole physics and doubly spacial relativity and the one assuming a perturbative departure from exact Lorentz invariance. Fixing the sensitivity factor and its energy dependence are essential inputs for a reliable confronting of our calculations to UHECR. The sensitivity factor is related to the special time of flight delay and the time structure of the signal. Furthermore, the upper and lower bounds to the parameter, a that characterizes the generalized uncertainly principle, have to be fixed in related physical systems such as the gamma rays bursts.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pin, F.G.

Outdoor sensor-based operation of autonomous robots has revealed to be an extremely challenging problem, mainly because of the difficulties encountered when attempting to represent the many uncertainties which are always present in the real world. These uncertainties are primarily due to sensor imprecisions and unpredictability of the environment, i.e., lack of full knowledge of the environment characteristics and dynamics. Two basic principles, or philosophies, and their associated methodologies are proposed in an attempt to remedy some of these difficulties. The first principle is based on the concept of ``minimal model`` for accomplishing given tasks and proposes to utilize only themore » minimum level of information and precision necessary to accomplish elemental functions of complex tasks. This approach diverges completely from the direction taken by most artificial vision studies which conventionally call for crisp and detailed analysis of every available component in the perception data. The paper will first review the basic concepts of this approach and will discuss its pragmatic feasibility when embodied in a behaviorist framework. The second principle which is proposed deals with implicit representation of uncertainties using Fuzzy Set Theory-based approximations and approximate reasoning, rather than explicit (crisp) representation through calculation and conventional propagation techniques. A framework which merges these principles and approaches is presented, and its application to the problem of sensor-based outdoor navigation of a mobile robot is discussed. Results of navigation experiments with a real car in actual outdoor environments are also discussed to illustrate the feasibility of the overall concept.« less

Using creation science to demonstrate evolution: application of a creationist method for visualizing gaps in the fossil record to a phylogenetic study of coelurosaurian dinosaurs.

PubMed

Senter, P

2010-08-01

It is important to demonstrate evolutionary principles in such a way that they cannot be countered by creation science. One such way is to use creation science itself to demonstrate evolutionary principles. Some creation scientists use classic multidimensional scaling (CMDS) to quantify and visualize morphological gaps or continuity between taxa, accepting gaps as evidence of independent creation and accepting continuity as evidence of genetic relatedness. Here, I apply CMDS to a phylogenetic analysis of coelurosaurian dinosaurs and show that it reveals morphological continuity between Archaeopteryx, other early birds, and a wide range of nonavian coelurosaurs. Creation scientists who use CMDS must therefore accept that these animals are genetically related. Other uses of CMDS for evolutionary biologists include the identification of taxa with much missing evolutionary history and the tracing of the progressive filling of morphological gaps in the fossil record through successive years of discovery.

A science confidence gap: Education, trust in scientific methods, and trust in scientific institutions in the United States, 2014.

PubMed

Achterberg, Peter; de Koster, Willem; van der Waal, Jeroen

2017-08-01

Following up on suggestions that attitudes toward science are multi-dimensional, we analyze nationally representative survey data collected in the United States in 2014 ( N = 2006), and demonstrate the existence of a science confidence gap: some people place great trust in scientific methods and principles, but simultaneously distrust scientific institutions. This science confidence gap is strongly associated with level of education: it is larger among the less educated than among the more educated. We investigate explanations for these educational differences. Whereas hypotheses deduced from reflexive-modernization theory do not pass the test, those derived from theorizing on the role of anomie are corroborated. The less educated are more anomic (they have more modernity-induced cultural discontents), which not only underlies their distrust in scientific institutions, but also fuels their trust in scientific methods and principles. This explains why this science confidence gap is most pronounced among the less educated.

Understanding and applying principles of social cognition and decision making in adaptive environmental governance.

PubMed

DeCaro, Daniel A; Arnol, Craig Anthony Tony; Boama, Emmanuel Frimpong; Garmestani, Ahjond S

2017-03-01

Environmental governance systems are under greater pressure to adapt and to cope with increased social and ecological uncertainty from stressors like climate change. We review principles of social cognition and decision making that shape and constrain how environmental governance systems adapt. We focus primarily on the interplay between key decision makers in society and legal systems. We argue that adaptive governance must overcome three cooperative dilemmas to facilitate adaptation: (1) encouraging collaborative problem solving, (2) garnering social acceptance and commitment, and (3) cultivating a culture of trust and tolerance for change and uncertainty. However, to do so governance systems must cope with biases in people's decision making that cloud their judgment and create conflict. These systems must also satisfy people's fundamental needs for self-determination, fairness, and security, ensuring that changes to environmental governance are perceived as legitimate, trustworthy, and acceptable. We discuss the implications of these principles for common governance solutions (e.g., public participation, enforcement) and conclude with methodological recommendations. We outline how scholars can investigate the social cognitive principles involved in cases of adaptive governance.

Understanding and applying principles of social cognition and decision making in adaptive environmental governance

PubMed Central

DeCaro, Daniel A.; Arnol, Craig Anthony (Tony); Boama, Emmanuel Frimpong; Garmestani, Ahjond S.

2018-01-01

Environmental governance systems are under greater pressure to adapt and to cope with increased social and ecological uncertainty from stressors like climate change. We review principles of social cognition and decision making that shape and constrain how environmental governance systems adapt. We focus primarily on the interplay between key decision makers in society and legal systems. We argue that adaptive governance must overcome three cooperative dilemmas to facilitate adaptation: (1) encouraging collaborative problem solving, (2) garnering social acceptance and commitment, and (3) cultivating a culture of trust and tolerance for change and uncertainty. However, to do so governance systems must cope with biases in people’s decision making that cloud their judgment and create conflict. These systems must also satisfy people’s fundamental needs for self-determination, fairness, and security, ensuring that changes to environmental governance are perceived as legitimate, trustworthy, and acceptable. We discuss the implications of these principles for common governance solutions (e.g., public participation, enforcement) and conclude with methodological recommendations. We outline how scholars can investigate the social cognitive principles involved in cases of adaptive governance. PMID:29780425

Test of Equivalence Principle at 10(-8) Level by a Dual-Species Double-Diffraction Raman Atom Interferometer.

PubMed

Zhou, Lin; Long, Shitong; Tang, Biao; Chen, Xi; Gao, Fen; Peng, Wencui; Duan, Weitao; Zhong, Jiaqi; Xiong, Zongyuan; Wang, Jin; Zhang, Yuanzhong; Zhan, Mingsheng

2015-07-03

We report an improved test of the weak equivalence principle by using a simultaneous 85Rb-87Rb dual-species atom interferometer. We propose and implement a four-wave double-diffraction Raman transition scheme for the interferometer, and demonstrate its ability in suppressing common-mode phase noise of Raman lasers after their frequencies and intensity ratios are optimized. The statistical uncertainty of the experimental data for Eötvös parameter η is 0.8×10(-8) at 3200 s. With various systematic errors corrected, the final value is η=(2.8±3.0)×10(-8). The major uncertainty is attributed to the Coriolis effect.

Do the Modified Uncertainty Principle and Polymer Quantization predict same physics?

NASA Astrophysics Data System (ADS)

Majumder, Barun; Sen, Sourav

2012-10-01

In this Letter we study the effects of the Modified Uncertainty Principle as proposed in Ali et al. (2009) [5] in simple quantum mechanical systems and study its thermodynamic properties. We have assumed that the quantum particles follow Maxwell-Boltzmann statistics with no spin. We compare our results with the results found in the GUP and polymer quantum mechanical frameworks. Interestingly we find that the corrected thermodynamic entities are exactly the same compared to the polymer results but the length scale considered has a theoretically different origin. Hence we express the need of further study for an investigation whether these two approaches are conceptually connected in the fundamental level.

Understanding the Uncertainty of an Effectiveness-Cost Ratio in Educational Resource Allocation: A Bayesian Approach

ERIC Educational Resources Information Center

Pan, Yilin

2016-01-01

Given the necessity to bridge the gap between what happened and what is likely to happen, this paper aims to explore how to apply Bayesian inference to cost-effectiveness analysis so as to capture the uncertainty of a ratio-type efficiency measure. The first part of the paper summarizes the characteristics of the evaluation data that are commonly…

Sources of uncertanity as a basis to fill the information gap in a response to flood

NASA Astrophysics Data System (ADS)

Kekez, Toni; Knezic, Snjezana

2016-04-01

Taking into account uncertainties in flood risk management remains a challenge due to difficulties in choosing adequate structural and/or non-structural risk management options. Despite stated measures wrong decisions are often being made when flood occurs. Parameter and structural uncertainties which include model and observation errors as well as lack of knowledge about system characteristics are the main considerations. Real time flood risk assessment methods are predominantly based on measured water level values and vulnerability as well as other relevant characteristics of flood affected area. The goal of this research is to identify sources of uncertainties and to minimize information gap between the point where the water level is measured and the affected area, taking into consideration main uncertainties that can affect risk value at the observed point or section of the river. Sources of uncertainties are identified and determined using system analysis approach and relevant uncertainties are included in the risk assessment model. With such methodological approach it is possible to increase response time with more effective risk assessment which includes uncertainty propagation model. Response phase could be better planned with adequate early warning systems resulting in more time and less costs to help affected areas and save human lives. Reliable and precise information is necessary to raise emergency operability level in order to enhance safety of citizens and reducing possible damage. The results of the EPISECC (EU funded FP7) project are used to validate potential benefits of this research in order to improve flood risk management and response methods. EPISECC aims at developing a concept of a common European Information Space for disaster response which, among other disasters, considers the floods.

Achieving Robustness to Uncertainty for Financial Decision-making

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barnum, George M.; Van Buren, Kendra L.; Hemez, Francois M.

2014-01-10

This report investigates the concept of robustness analysis to support financial decision-making. Financial models, that forecast future stock returns or market conditions, depend on assumptions that might be unwarranted and variables that might exhibit large fluctuations from their last-known values. The analysis of robustness explores these sources of uncertainty, and recommends model settings such that the forecasts used for decision-making are as insensitive as possible to the uncertainty. A proof-of-concept is presented with the Capital Asset Pricing Model. The robustness of model predictions is assessed using info-gap decision theory. Info-gaps are models of uncertainty that express the “distance,” or gapmore » of information, between what is known and what needs to be known in order to support the decision. The analysis yields a description of worst-case stock returns as a function of increasing gaps in our knowledge. The analyst can then decide on the best course of action by trading-off worst-case performance with “risk”, which is how much uncertainty they think needs to be accommodated in the future. The report also discusses the Graphical User Interface, developed using the MATLAB® programming environment, such that the user can control the analysis through an easy-to-navigate interface. Three directions of future work are identified to enhance the present software. First, the code should be re-written using the Python scientific programming software. This change will achieve greater cross-platform compatibility, better portability, allow for a more professional appearance, and render it independent from a commercial license, which MATLAB® requires. Second, a capability should be developed to allow users to quickly implement and analyze their own models. This will facilitate application of the software to the evaluation of proprietary financial models. The third enhancement proposed is to add the ability to evaluate multiple models simultaneously. When two models reflect past data with similar accuracy, the more robust of the two is preferable for decision-making because its predictions are, by definition, less sensitive to the uncertainty.« less

Planning water supply under uncertainty - benefits and limitations of RDM, Info-Gap, economic optimization and many-objective optimization

NASA Astrophysics Data System (ADS)

Matrosov, E.; Padula, S.; Huskova, I.; Harou, J. J.

2012-12-01

Population growth and the threat of drier or changed climates are likely to increase water scarcity world-wide. A combination of demand management (water conservation) and new supply infrastructure is often needed to meet future projected demands. In this case system planners must decide what to implement, when and at what capacity. Choices can range from infrastructure to policies or a mix of the two, culminating in a complex planning problem. Decision making under uncertainty frameworks can be used to help planners with this planning problem. This presentation introduces, applies and compares four decision making under uncertainty frameworks. The application is to the Thames basin water resource system which includes the city of London. The approaches covered here include least-economic cost capacity expansion optimization (EO), Robust Decision Making (RDM), Info-Gap Decision Theory (Info-gap) and many-objective evolutionary optimization (MOEO). EO searches for the least-economic cost program, i.e. the timing, sizing, and choice of supply-demand management actions/upgrades which meet projected water demands. Instead of striving for optimality, the RDM and Info-gap approaches help build plans that are robust to 'deep' uncertainty in future conditions. The MOEO framework considers multiple performance criteria and uses water systems simulators as a function evaluator for the evolutionary algorithm. Visualizations show Pareto approximate tradeoffs between multiple objectives. In this presentation we detail the application of each framework to the Thames basin (including London) water resource planning problem. Supply and demand options are proposed by the major water companies in the basin. We apply the EO method using a 29 year time horizon and an annual time step considering capital, operating (fixed and variable), social and environmental costs. The method considers all plausible combinations of supply and conservation schemes and capacities proposed by water companies and generates the least-economic cost annual plan. The RDM application uses stochastic simulation under a weekly time-step and regret analysis to choose a candidate strategy. We then use a statistical cluster algorithm to identify future states of the world under which the strategy is vulnerable. The method explicitly considers the effects of uncertainty in supply, demands and energy price on multiple performance criteria. The Info-gap approach produces robustness and opportuneness plots that show the performance of different plans under the most dire and favorable sets of future conditions. The same simulator, supply and demand options and uncertainties are considered as in the RDM application. The MOEO application considers many more combinations of supply and demand options while still employing a simulator that enables a more realistic representation of the physical system and operating rules. A computer cluster is employed to ease the computational burden. Visualization software allows decision makers to interactively view tradeoffs in many dimensions. Benefits and limitations of each framework are discussed and recommendations for future planning in the basin are provided.

Principles of Quantum Mechanics

NASA Astrophysics Data System (ADS)

Landé, Alfred

2013-10-01

Preface; Introduction: 1. Observation and interpretation; 2. Difficulties of the classical theories; 3. The purpose of quantum theory; Part I. Elementary Theory of Observation (Principle of Complementarity): 4. Refraction in inhomogeneous media (force fields); 5. Scattering of charged rays; 6. Refraction and reflection at a plane; 7. Absolute values of momentum and wave length; 8. Double ray of matter diffracting light waves; 9. Double ray of matter diffracting photons; 10. Microscopic observation of ρ (x) and σ (p); 11. Complementarity; 12. Mathematical relation between ρ (x) and σ (p) for free particles; 13. General relation between ρ (q) and σ (p); 14. Crystals; 15. Transition density and transition probability; 16. Resultant values of physical functions; matrix elements; 17. Pulsating density; 18. General relation between ρ (t) and σ (є); 19. Transition density; matrix elements; Part II. The Principle of Uncertainty: 20. Optical observation of density in matter packets; 21. Distribution of momenta in matter packets; 22. Mathematical relation between ρ and σ; 23. Causality; 24. Uncertainty; 25. Uncertainty due to optical observation; 26. Dissipation of matter packets; rays in Wilson Chamber; 27. Density maximum in time; 28. Uncertainty of energy and time; 29. Compton effect; 30. Bothe-Geiger and Compton-Simon experiments; 31. Doppler effect; Raman effect; 32. Elementary bundles of rays; 33. Jeans' number of degrees of freedom; 34. Uncertainty of electromagnetic field components; Part III. The Principle of Interference and Schrödinger's equation: 35. Physical functions; 36. Interference of probabilities for p and q; 37. General interference of probabilities; 38. Differential equations for Ψp (q) and Xq (p); 39. Differential equation for фβ (q); 40. The general probability amplitude Φβ' (Q); 41. Point transformations; 42. General theorem of interference; 43. Conjugate variables; 44. Schrödinger's equation for conservative systems; 45. Schrödinger's equation for non-conservative systems; 46. Pertubation theory; 47. Orthogonality, normalization and Hermitian conjugacy; 48. General matrix elements; Part IV. The Principle of Correspondence: 49. Contact transformations in classical mechanics; 50. Point transformations; 51. Contact transformations in quantum mechanics; 52. Constants of motion and angular co-ordinates; 53. Periodic orbits; 54. De Broglie and Schrödinger function; correspondence to classical mechanics; 55. Packets of probability; 56. Correspondence to hydrodynamics; 57. Motion and scattering of wave packets; 58. Formal correspondence between classical and quantum mechanics; Part V. Mathematical Appendix: Principle of Invariance: 59. The general theorem of transformation; 60. Operator calculus; 61. Exchange relations; three criteria for conjugacy; 62. First method of canonical transformation; 63. Second method of canonical transformation; 64. Proof of the transformation theorem; 65. Invariance of the matrix elements against unitary transformations; 66. Matrix mechanics; Index of literature; Index of names and subjects.

Fundamental gaps with approximate density functionals: The derivative discontinuity revealed from ensemble considerations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kraisler, Eli; Kronik, Leeor

2014-05-14

The fundamental gap is a central quantity in the electronic structure of matter. Unfortunately, the fundamental gap is not generally equal to the Kohn-Sham gap of density functional theory (DFT), even in principle. The two gaps differ precisely by the derivative discontinuity, namely, an abrupt change in slope of the exchange-correlation energy as a function of electron number, expected across an integer-electron point. Popular approximate functionals are thought to be devoid of a derivative discontinuity, strongly compromising their performance for prediction of spectroscopic properties. Here we show that, in fact, all exchange-correlation functionals possess a derivative discontinuity, which arises naturallymore » from the application of ensemble considerations within DFT, without any empiricism. This derivative discontinuity can be expressed in closed form using only quantities obtained in the course of a standard DFT calculation of the neutral system. For small, finite systems, addition of this derivative discontinuity indeed results in a greatly improved prediction for the fundamental gap, even when based on the most simple approximate exchange-correlation density functional – the local density approximation (LDA). For solids, the same scheme is exact in principle, but when applied to LDA it results in a vanishing derivative discontinuity correction. This failure is shown to be directly related to the failure of LDA in predicting fundamental gaps from total energy differences in extended systems.« less

First-principles study of electronic structure modulations in graphene on Ru(0001) by Au intercalation

NASA Astrophysics Data System (ADS)

Nishidate, Kazume; Tanibayashi, Satoru; Yoshimoto, Noriyuki; Hasegawa, Masayuki

2018-03-01

First-principles calculations based on density functional theory are used to explore the electronic-structure modulations in graphene on Ru(0001) by Au intercalation. We first use a lattice-matched model to demonstrate that a substantial band gap is induced in graphene by sufficiently strong A-B sublattice symmetry breaking. This band gap opening occurs even in the absence of hybridization between graphene π states and Au states, and a strong sublattice asymmetry is established for a small separation (d ) between the graphene and Au layer, typically, d <3.0 Å , which can actually be achieved for a low Au coverage. In realistic situations, which are mimicked using lattice-mismatched models, graphene π states near the Dirac point easily hybridize with nearby (in energy) Au states even for a van der Waals distance, d ˜3.4 Å , and this hybridization usually dictates a band gap opening in graphene. In that case, the top parts of the intact Dirac cones survive the hybridization and are isolated to form midgap states within the hybridization gap, denying that the band gap is induced by sublattice symmetry breaking. This feature of a band gap opening is similar to that found for the so-called "first" graphene layer on silicon carbide (SiC) and the predicted band gap and doping level are in good agreement with the experiments for graphene/Au/Ru(0001).

DETERMINING MOTOR INERTIA OF A STRESS-CONTROLLED RHEOMETER.

PubMed

Klemuk, Sarah A; Titze, Ingo R

2009-01-01

Viscoelastic measurements made with a stress-controlled rheometer are affected by system inertia. Of all contributors to system inertia, motor inertia is the largest. Its value is usually determined empirically and precision is rarely if ever specified. Inertia uncertainty has negligible effects on rheologic measurements below the coupled motor/plate/sample resonant frequency. But above the resonant frequency, G' values of soft viscoelastic materials such as dispersions, gels, biomaterials, and non-Newtonian polymers, err quadratically due to inertia uncertainty. In the present investigation, valid rheologic measurements were achieved near and above the coupled resonant frequency for a non-Newtonian reference material. At these elevated frequencies, accuracy in motor inertia is critical. Here we compare two methods for determining motor-inertia accurately. For the first (commercially-used) phase method, frequency responses of standard fluids were measured. Phase between G' and G" was analyzed at 5-70 Hz for motor inertia values of 50-150% of the manufacturer's nominal value. For a newly-devised two-plate method (10 mm and 60 mm parallel plates), dynamic measurements of a non-Newtonian standard were collected. Using a linear equation of motion with inertia, viscosity, and elasticity coefficients, G' expressions for both plates were equated and motor inertia was determined to be accurate (by comparison to the phase method) with a precision of ± 3%. The newly developed two-plate method had advantages of expressly eliminating dependence on gap, was explicitly derived from basic principles, quantified the error, and required fewer experiments than the commercially used phase method.

Biological effectiveness of neutrons: Research needs

NASA Astrophysics Data System (ADS)

Casarett, G. W.; Braby, L. A.; Broerse, J. J.; Elkind, M. M.; Goodhead, D. T.; Oleinick, N. L.

1994-02-01

The goal of this report was to provide a conceptual plan for a research program that would provide a basis for determining more precisely the biological effectiveness of neutron radiation with emphasis on endpoints relevant to the protection of human health. This report presents the findings of the experts for seven particular categories of scientific information on neutron biological effectiveness. Chapter 2 examines the radiobiological mechanisms underlying the assumptions used to estimate human risk from neutrons and other radiations. Chapter 3 discusses the qualitative and quantitative models used to organize and evaluate experimental observations and to provide extrapolations where direct observations cannot be made. Chapter 4 discusses the physical principles governing the interaction of radiation with biological systems and the importance of accurate dosimetry in evaluating radiation risk and reducing the uncertainty in the biological data. Chapter 5 deals with the chemical and molecular changes underlying cellular responses and the LET dependence of these changes. Chapter 6, in turn, discusses those cellular and genetic changes which lead to mutation or neoplastic transformation. Chapters 7 and 8 examine deterministic and stochastic effects, respectively, and the data required for the prediction of such effects at different organizational levels and for the extrapolation from experimental results in animals to risks for man. Gaps and uncertainties in this data are examined relative to data required for establishing radiation protection standards for neutrons and procedures for the effective and safe use of neutron and other high-LET radiation therapy.

First-principle study of effect of variation of `x' on the band alignment in CZTS1-xSex

NASA Astrophysics Data System (ADS)

Ghemud, Vipul; Kshirsagar, Anjali

2018-04-01

The present work concentrates on the electronic structure study of CZTS1-xSex alloy with x ranging from 0 to 1. For the alloy study, we have carried out first-principles calculations employing generalized gradient approximation for structural optimization and further hybrid functional approach to compare the optical band gap with that obtained from the experiments. A systematic increase in the lattice parameters with lowering of band gap from 1.52eV to 1.04eV is seen with increasing Se concentration from 0 to 100%, however the lowering of valence band edge and conduction band edge is not linear with the concentration variation. Our results indicate that the lowering of band gap is a result increased Cu:d and Se:p hybridization with increasing `x'.

First principles investigation of GaNbO{sub 4} as a photocatalytic material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Neelam, E-mail: sneelam@issc.unipune.ac.in; Verma, Mukta; Shah, Vaishali

We have performed first principles density functional total energy calculations on pure and doped GaNbO{sub 4} to investigate its applicability as a photo catalyst. Pure GaNbO{sub 4} is an indirect, wide band gap semiconductor similar to the widely investigated TiO{sub 2} which is known to be a photo catalyst in UV light [K. Yang et. al. Chem. Mater. 20, 6528 (2008)]. S atom doping of TiO{sub 2} reduces the band gap [F. Tian et. al. J. Phys. Chem. B 110, 17866 (2006)], and increases its efficiency in the visible light range. It has been experimentally reported that S doping ofmore » GaNbO{sub 4} at the O site, decreases its photo catalytic efficiency. Our band structure calculations show that both pure and doped GaNbO{sub 4} have indirect band gaps and S atom doping reduces the band gap in agreement with experiments. The decrease in the band gap is due to the lowering of the conduction band minimum towards the Fermi level. An unequal reduction in the band gap was observed at the four inequivalent O sites chosen for S doping. This suggests that the photo catalytic activity varies with the dopant site.« less

Band Structure Engineering of Cs2AgBiBr6 Perovskite through Order-Disordered Transition: A First-Principle Study.

PubMed

Yang, Jingxiu; Zhang, Peng; Wei, Su-Huai

2018-01-04

Cs 2 AgBiBr 6 was proposed as one of the inorganic, stable, and nontoxic replacements of the methylammonium lead halides (CH 3 NH 3 PbI 3 , which is currently considered as one of the most promising light-harvesting material for solar cells). However, the wide indirect band gap of Cs 2 AgBiBr 6 suggests that its application in photovoltaics is limited. Using the first-principle calculation, we show that by controlling the ordering parameter at the mixed sublattice, the band gap of Cs 2 AgBiBr 6 can vary continuously from a wide indirect band gap of 1.93 eV for the fully ordered double-perovskite structure to a small pseudodirect band gap of 0.44 eV for the fully random alloy. Therefore, one can achieve better light absorption simply by controlling the growth temperature and thus the ordering parameters and band gaps. We also show that controlled doping in Cs 2 AgBiBr 6 can change the energy difference between ordered and disordered Cs 2 AgBiBr 6 , thus providing further control of the ordering parameters and the band gaps. Our study, therefore, provides a novel approach to carry out band structure engineering in the mixed perovskites for optoelectronic applications.

Robust evaluation of time series classification algorithms for structural health monitoring

NASA Astrophysics Data System (ADS)

Harvey, Dustin Y.; Worden, Keith; Todd, Michael D.

2014-03-01

Structural health monitoring (SHM) systems provide real-time damage and performance information for civil, aerospace, and mechanical infrastructure through analysis of structural response measurements. The supervised learning methodology for data-driven SHM involves computation of low-dimensional, damage-sensitive features from raw measurement data that are then used in conjunction with machine learning algorithms to detect, classify, and quantify damage states. However, these systems often suffer from performance degradation in real-world applications due to varying operational and environmental conditions. Probabilistic approaches to robust SHM system design suffer from incomplete knowledge of all conditions a system will experience over its lifetime. Info-gap decision theory enables nonprobabilistic evaluation of the robustness of competing models and systems in a variety of decision making applications. Previous work employed info-gap models to handle feature uncertainty when selecting various components of a supervised learning system, namely features from a pre-selected family and classifiers. In this work, the info-gap framework is extended to robust feature design and classifier selection for general time series classification through an efficient, interval arithmetic implementation of an info-gap data model. Experimental results are presented for a damage type classification problem on a ball bearing in a rotating machine. The info-gap framework in conjunction with an evolutionary feature design system allows for fully automated design of a time series classifier to meet performance requirements under maximum allowable uncertainty.

The physical origins of the uncertainty theorem

NASA Astrophysics Data System (ADS)

Giese, Albrecht

2013-10-01

The uncertainty principle is an important element of quantum mechanics. It deals with certain pairs of physical parameters which cannot be determined to an arbitrary level of precision at the same time. According to the so-called Copenhagen interpretation of quantum mechanics, this uncertainty is an intrinsic property of the physical world. - This paper intends to show that there are good reasons for adopting a different view. According to the author, the uncertainty is not a property of the physical world but rather a limitation of our knowledge about the actual state of a physical process. This view conforms to the quantum theory of Louis de Broglie and to Albert Einstein's interpretation.

Temporal prediction errors modulate task-switching performance

PubMed Central

Limongi, Roberto; Silva, Angélica M.; Góngora-Costa, Begoña

2015-01-01

We have previously shown that temporal prediction errors (PEs, the differences between the expected and the actual stimulus’ onset times) modulate the effective connectivity between the anterior cingulate cortex and the right anterior insular cortex (rAI), causing the activity of the rAI to decrease. The activity of the rAI is associated with efficient performance under uncertainty (e.g., changing a prepared behavior when a change demand is not expected), which leads to hypothesize that temporal PEs might disrupt behavior-change performance under uncertainty. This hypothesis has not been tested at a behavioral level. In this work, we evaluated this hypothesis within the context of task switching and concurrent temporal predictions. Our participants performed temporal predictions while observing one moving ball striking a stationary ball which bounced off with a variable temporal gap. Simultaneously, they performed a simple color comparison task. In some trials, a change signal made the participants change their behaviors. Performance accuracy decreased as a function of both the temporal PE and the delay. Explaining these results without appealing to ad hoc concepts such as “executive control” is a challenge for cognitive neuroscience. We provide a predictive coding explanation. We hypothesize that exteroceptive and proprioceptive minimization of PEs would converge in a fronto-basal ganglia network which would include the rAI. Both temporal gaps (or uncertainty) and temporal PEs would drive and modulate this network respectively. Whereas the temporal gaps would drive the activity of the rAI, the temporal PEs would modulate the endogenous excitatory connections of the fronto-striatal network. We conclude that in the context of perceptual uncertainty, the system is not able to minimize perceptual PE, causing the ongoing behavior to finalize and, in consequence, disrupting task switching. PMID:26379568

Temporal prediction errors modulate task-switching performance.

PubMed

Limongi, Roberto; Silva, Angélica M; Góngora-Costa, Begoña

2015-01-01

We have previously shown that temporal prediction errors (PEs, the differences between the expected and the actual stimulus' onset times) modulate the effective connectivity between the anterior cingulate cortex and the right anterior insular cortex (rAI), causing the activity of the rAI to decrease. The activity of the rAI is associated with efficient performance under uncertainty (e.g., changing a prepared behavior when a change demand is not expected), which leads to hypothesize that temporal PEs might disrupt behavior-change performance under uncertainty. This hypothesis has not been tested at a behavioral level. In this work, we evaluated this hypothesis within the context of task switching and concurrent temporal predictions. Our participants performed temporal predictions while observing one moving ball striking a stationary ball which bounced off with a variable temporal gap. Simultaneously, they performed a simple color comparison task. In some trials, a change signal made the participants change their behaviors. Performance accuracy decreased as a function of both the temporal PE and the delay. Explaining these results without appealing to ad hoc concepts such as "executive control" is a challenge for cognitive neuroscience. We provide a predictive coding explanation. We hypothesize that exteroceptive and proprioceptive minimization of PEs would converge in a fronto-basal ganglia network which would include the rAI. Both temporal gaps (or uncertainty) and temporal PEs would drive and modulate this network respectively. Whereas the temporal gaps would drive the activity of the rAI, the temporal PEs would modulate the endogenous excitatory connections of the fronto-striatal network. We conclude that in the context of perceptual uncertainty, the system is not able to minimize perceptual PE, causing the ongoing behavior to finalize and, in consequence, disrupting task switching.

Turnaround in Texas: How One District Closed Its Minority Achievement Gap.

ERIC Educational Resources Information Center

Cook, Glenn

2003-01-01

Describes how one district closed its minority achievement gap by employing the Brazosport model, a combination of effective-schools research and Total Quality Management principles. The model includes an eight-step "plan-do-check" instructional cycle for teachers and emphasizes teacher training and tracking data. Student-achievement…

Close Early Learning Gaps with Rigorous DAP

ERIC Educational Resources Information Center

Brown, Christopher P.; Mowry, Brian

2015-01-01

Rigorous DAP (developmentally appropriate practices) is a set of 11 principles of instruction intended to help close early childhood learning gaps. Academically rigorous learning environments create the conditions for children to learn at high levels. While academic rigor focuses on one dimension of education--academic--DAP considers the whole…

Uncertainty estimation of the self-thinning process by Maximum-Entropy Principle

Treesearch

Shoufan Fang; George Z. Gertner

2000-01-01

When available information is scarce, the Maximum-Entropy Principle can estimate the distributions of parameters. In our case study, we estimated the distributions of the parameters of the forest self-thinning process based on literature information, and we derived the conditional distribution functions and estimated the 95 percent confidence interval (CI) of the self-...

Uncertainty, imprecision, and the precautionary principle in climate change assessment.

PubMed

Borsuk, M E; Tomassini, L

2005-01-01

Statistical decision theory can provide useful support for climate change decisions made under conditions of uncertainty. However, the probability distributions used to calculate expected costs in decision theory are themselves subject to uncertainty, disagreement, or ambiguity in their specification. This imprecision can be described using sets of probability measures, from which upper and lower bounds on expectations can be calculated. However, many representations, or classes, of probability measures are possible. We describe six of the more useful classes and demonstrate how each may be used to represent climate change uncertainties. When expected costs are specified by bounds, rather than precise values, the conventional decision criterion of minimum expected cost is insufficient to reach a unique decision. Alternative criteria are required, and the criterion of minimum upper expected cost may be desirable because it is consistent with the precautionary principle. Using simple climate and economics models as an example, we determine the carbon dioxide emissions levels that have minimum upper expected cost for each of the selected classes. There can be wide differences in these emissions levels and their associated costs, emphasizing the need for care when selecting an appropriate class.

The action uncertainty principle for continuous measurements

NASA Astrophysics Data System (ADS)

Mensky, Michael B.

1996-02-01

The action uncertainty principle (AUP) for the specification of the most probable readouts of continuous quantum measurements is proved, formulated in different forms and analyzed (for nonlinear as well as linear systems). Continuous monitoring of an observable A(p,q,t) with resolution Δa( t) is considered. The influence of the measurement process on the evolution of the measured system (quantum measurement noise) is presented by an additional term δ F(t)A(p,q,t) in the Hamiltonian where the function δ F (generalized fictitious force) is restricted by the AUP ∫|δ F(t)| Δa( t) d t ≲ and arbitrary otherwise. Quantum-nondemolition (QND) measurements are analyzed with the help of the AUP. A simple uncertainty relation for continuous quantum measurements is derived. It states that the area of a certain band in the phase space should be of the order of. The width of the band depends on the measurement resolution while its length is determined by the deviation of the system, due to the measurement, from classical behavior.

Modelling guidelines--terminology and guiding principles

NASA Astrophysics Data System (ADS)

Refsgaard, Jens Christian; Henriksen, Hans Jørgen

2004-01-01

Some scientists argue, with reference to Popper's scientific philosophical school, that models cannot be verified or validated. Other scientists and many practitioners nevertheless use these terms, but with very different meanings. As a result of an increasing number of examples of model malpractice and mistrust to the credibility of models, several modelling guidelines are being elaborated in recent years with the aim of improving the quality of modelling studies. This gap between the views and the lack of consensus experienced in the scientific community and the strongly perceived need for commonly agreed modelling guidelines is constraining the optimal use and benefits of models. This paper proposes a framework for quality assurance guidelines, including a consistent terminology and a foundation for a methodology bridging the gap between scientific philosophy and pragmatic modelling. A distinction is made between the conceptual model, the model code and the site-specific model. A conceptual model is subject to confirmation or falsification like scientific theories. A model code may be verified within given ranges of applicability and ranges of accuracy, but it can never be universally verified. Similarly, a model may be validated, but only with reference to site-specific applications and to pre-specified performance (accuracy) criteria. Thus, a model's validity will always be limited in terms of space, time, boundary conditions and types of application. This implies a continuous interaction between manager and modeller in order to establish suitable accuracy criteria and predictions associated with uncertainty analysis.

TSUNAMI Primer: A Primer for Sensitivity/Uncertainty Calculations with SCALE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rearden, Bradley T; Mueller, Don; Bowman, Stephen M

2009-01-01

This primer presents examples in the application of the SCALE/TSUNAMI tools to generate k{sub eff} sensitivity data for one- and three-dimensional models using TSUNAMI-1D and -3D and to examine uncertainties in the computed k{sub eff} values due to uncertainties in the cross-section data used in their calculation. The proper use of unit cell data and need for confirming the appropriate selection of input parameters through direct perturbations are described. The uses of sensitivity and uncertainty data to identify and rank potential sources of computational bias in an application system and TSUNAMI tools for assessment of system similarity using sensitivity andmore » uncertainty criteria are demonstrated. Uses of these criteria in trending analyses to assess computational biases, bias uncertainties, and gap analyses are also described. Additionally, an application of the data adjustment tool TSURFER is provided, including identification of specific details of sources of computational bias.« less

A Practical Approach to Address Uncertainty in Stakeholder Deliberations.

PubMed

Gregory, Robin; Keeney, Ralph L

2017-03-01

This article addresses the difficulties of incorporating uncertainty about consequence estimates as part of stakeholder deliberations involving multiple alternatives. Although every prediction of future consequences necessarily involves uncertainty, a large gap exists between common practices for addressing uncertainty in stakeholder deliberations and the procedures of prescriptive decision-aiding models advanced by risk and decision analysts. We review the treatment of uncertainty at four main phases of the deliberative process: with experts asked to describe possible consequences of competing alternatives, with stakeholders who function both as individuals and as members of coalitions, with the stakeholder committee composed of all stakeholders, and with decisionmakers. We develop and recommend a model that uses certainty equivalents as a theoretically robust and practical approach for helping diverse stakeholders to incorporate uncertainties when evaluating multiple-objective alternatives as part of public policy decisions. © 2017 Society for Risk Analysis.

Data-driven Applications for the Sun-Earth System

NASA Astrophysics Data System (ADS)

Kondrashov, D. A.

2016-12-01

Advances in observational and data mining techniques allow extracting information from the large volume of Sun-Earth observational data that can be assimilated into first principles physical models. However, equations governing Sun-Earth phenomena are typically nonlinear, complex, and high-dimensional. The high computational demand of solving the full governing equations over a large range of scales precludes the use of a variety of useful assimilative tools that rely on applied mathematical and statistical techniques for quantifying uncertainty and predictability. Effective use of such tools requires the development of computationally efficient methods to facilitate fusion of data with models. This presentation will provide an overview of various existing as well as newly developed data-driven techniques adopted from atmospheric and oceanic sciences that proved to be useful for space physics applications, such as computationally efficient implementation of Kalman Filter in radiation belts modeling, solar wind gap-filling by Singular Spectrum Analysis, and low-rank procedure for assimilation of low-altitude ionospheric magnetic perturbations into the Lyon-Fedder-Mobarry (LFM) global magnetospheric model. Reduced-order non-Markovian inverse modeling and novel data-adaptive decompositions of Sun-Earth datasets will be also demonstrated.

Socialization of Young Children: Successful Principles and Models.

ERIC Educational Resources Information Center

Schieser, Hans A.

This discussion focuses on several principles and models of early childhood education which have been used to improve children's ability to live and work with others. Modern problems of socialization in early childhood are discussed in terms of the generation gap in industrial societies, the development of the "private" family with…

Providing Experiential Business and Management Training for Biomedical Research Trainees

ERIC Educational Resources Information Center

Petrie, Kimberly A.; Carnahan, Robert H.; Brown, Abigail M.; Gould, Kathleen L.

2017-01-01

Many biomedical PhD trainees lack exposure to business principles, which limits their competitiveness and effectiveness in academic and industry careers. To fill this training gap, we developed Business and Management Principles for Scientists, a semester-long program that combined didactic exposure to business fundamentals with practical…

The State-Society/Citizen Relationship in Security Analysis: Implications for Planning and Implementation of U.S. Intervention and Peace/State-Building Operations

DTIC Science & Technology

2015-04-01

of the state. Such threats may come into existence when 9 the organizing principles of two states contradict each other in a context where the...security is that the normal condition of actors in a market econ - omy is one of risk, competition, and uncertainty.12 In other words, the actors in the...liberal principles , federative states have no natural unifying principle and, consequently, are more vulnerable to dismemberment, separatism, and

Uncertainty evaluation of thickness and warp of a silicon wafer measured by a spectrally resolved interferometer

NASA Astrophysics Data System (ADS)

Praba Drijarkara, Agustinus; Gergiso Gebrie, Tadesse; Lee, Jae Yong; Kang, Chu-Shik

2018-06-01

Evaluation of uncertainty of thickness and gravity-compensated warp of a silicon wafer measured by a spectrally resolved interferometer is presented. The evaluation is performed in a rigorous manner, by analysing the propagation of uncertainty from the input quantities through all the steps of measurement functions, in accordance with the ISO Guide to the Expression of Uncertainty in Measurement. In the evaluation, correlation between input quantities as well as uncertainty attributed to thermal effect, which were not included in earlier publications, are taken into account. The temperature dependence of the group refractive index of silicon was found to be nonlinear and varies widely within a wafer and also between different wafers. The uncertainty evaluation described here can be applied to other spectral interferometry applications based on similar principles.

Conditional uncertainty principle

NASA Astrophysics Data System (ADS)

Gour, Gilad; Grudka, Andrzej; Horodecki, Michał; Kłobus, Waldemar; Łodyga, Justyna; Narasimhachar, Varun

2018-04-01

We develop a general operational framework that formalizes the concept of conditional uncertainty in a measure-independent fashion. Our formalism is built upon a mathematical relation which we call conditional majorization. We define conditional majorization and, for the case of classical memory, we provide its thorough characterization in terms of monotones, i.e., functions that preserve the partial order under conditional majorization. We demonstrate the application of this framework by deriving two types of memory-assisted uncertainty relations, (1) a monotone-based conditional uncertainty relation and (2) a universal measure-independent conditional uncertainty relation, both of which set a lower bound on the minimal uncertainty that Bob has about Alice's pair of incompatible measurements, conditioned on arbitrary measurement that Bob makes on his own system. We next compare the obtained relations with their existing entropic counterparts and find that they are at least independent.

Quantification of uncertainty in first-principles predicted mechanical properties of solids: Application to solid ion conductors

NASA Astrophysics Data System (ADS)

Ahmad, Zeeshan; Viswanathan, Venkatasubramanian

2016-08-01

Computationally-guided material discovery is being increasingly employed using a descriptor-based screening through the calculation of a few properties of interest. A precise understanding of the uncertainty associated with first-principles density functional theory calculated property values is important for the success of descriptor-based screening. The Bayesian error estimation approach has been built in to several recently developed exchange-correlation functionals, which allows an estimate of the uncertainty associated with properties related to the ground state energy, for example, adsorption energies. Here, we propose a robust and computationally efficient method for quantifying uncertainty in mechanical properties, which depend on the derivatives of the energy. The procedure involves calculating energies around the equilibrium cell volume with different strains and fitting the obtained energies to the corresponding energy-strain relationship. At each strain, we use instead of a single energy, an ensemble of energies, giving us an ensemble of fits and thereby, an ensemble of mechanical properties associated with each fit, whose spread can be used to quantify its uncertainty. The generation of ensemble of energies is only a post-processing step involving a perturbation of parameters of the exchange-correlation functional and solving for the energy non-self-consistently. The proposed method is computationally efficient and provides a more robust uncertainty estimate compared to the approach of self-consistent calculations employing several different exchange-correlation functionals. We demonstrate the method by calculating the uncertainty bounds for several materials belonging to different classes and having different structures using the developed method. We show that the calculated uncertainty bounds the property values obtained using three different GGA functionals: PBE, PBEsol, and RPBE. Finally, we apply the approach to calculate the uncertainty associated with the DFT-calculated elastic properties of solid state Li-ion and Na-ion conductors.

Improving the Pharmacologic Management of Pain in Older Adults: Identifying the Research Gaps and Methods to Address Them

PubMed Central

Reid, M. C.; Bennett, David A.; Chen, Wen G.; Eldadah, Basil A.; Farrar, John T.; Ferrell, Bruce; Gallagher, Rollin M.; Hanlon, Joseph T.; Herr, Keela; Horn, Susan D.; Inturrisi, Charles E.; Lemtouni, Salma; Lin, Yu Woody; Michaud, Kaleb; Morrison, R. Sean; Neogi, Tuhina; Porter, Linda L.; Solomon, Daniel H.; Von Korff, Michael; Weiss, Karen; Witter, James; Zacharoff, Kevin L.

2011-01-01

Objective There has been a growing recognition of the need for better pharmacologic management of chronic pain among older adults. To address this need, the National Institutes of Health Pain Consortium sponsored an “Expert Panel Discussion on the Pharmacological Management of Chronic Pain in Older Adults” conference in September, 2010, to identify research gaps and strategies to address them. Specific emphasis was placed on ascertaining gaps regarding use of opioid and non-steroidal anti-inflammatory medications because of continued uncertainties regarding their risks and benefits. Design Eighteen panel members provided oral presentations; each was followed by a multidisciplinary panel discussion. Meeting transcripts and panelists’ slide presentations were reviewed to identify the gaps, and the types of studies and research methods panelists suggested could best address them. Results Fifteen gaps were identified in the areas of treatment(e.g., uncertainty regarding the long-term safety and efficacy of commonly prescribed analgesics), epidemiology (e.g., lack of knowledge regarding the course of common pain syndromes), and implementation(e.g., limited understanding of optimal strategies to translate evidence-based pain treatments into practice). Analyses of data from electronic health care databases, observational cohort studies, and ongoing cohort studies (augmented with pain and other relevant outcomes measures) were felt to be practical methods for building an age-appropriate evidence base to improve the pharmacologic management of pain in later life. Conclusions Addressing the gaps presented in the current report was judged by the panel to have substantial potential to improve the health and well being of older adults with chronic pain. PMID:21834914

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pramanik, Souvik, E-mail: souvick.in@gmail.com; Moussa, Mohamed, E-mail: mohamed.ibrahim@fsc.bu.edu.eg; Faizal, Mir, E-mail: f2mir@uwaterloo.ca

In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. Withmore » this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result.« less

Thermodynamics of a class of regular black holes with a generalized uncertainty principle

NASA Astrophysics Data System (ADS)

Maluf, R. V.; Neves, Juliano C. S.

2018-05-01

In this article, we present a study on thermodynamics of a class of regular black holes. Such a class includes Bardeen and Hayward regular black holes. We obtained thermodynamic quantities like the Hawking temperature, entropy, and heat capacity for the entire class. As part of an effort to indicate some physical observable to distinguish regular black holes from singular black holes, we suggest that regular black holes are colder than singular black holes. Besides, contrary to the Schwarzschild black hole, that class of regular black holes may be thermodynamically stable. From a generalized uncertainty principle, we also obtained the quantum-corrected thermodynamics for the studied class. Such quantum corrections provide a logarithmic term for the quantum-corrected entropy.

Exploring the charge localization and band gap opening of borophene: a first-principles study.

PubMed

Kistanov, Andrey A; Cai, Yongqing; Zhou, Kun; Srikanth, Narasimalu; Dmitriev, Sergey V; Zhang, Yong-Wei

2018-01-18

Recently synthesized two-dimensional (2D) boron, borophene, exhibits a novel metallic behavior rooted in the s-p orbital hybridization, distinctively different from other 2D materials such as sulfides/selenides and semi-metallic graphene. This unique feature of borophene implies new routes for charge delocalization and band gap opening. Herein, using first-principles calculations, we explore the routes to localize the carriers and open the band gap of borophene via chemical functionalization, ribbon construction, and defect engineering. The metallicity of borophene is found to be remarkably robust against H- and F-functionalization and the presence of vacancies. Interestingly, a strong odd-even oscillation of the electronic structure with width is revealed for H-functionalized borophene nanoribbons, while an ultra-high work function (∼7.83 eV) is found for the F-functionalized borophene due to its strong charge transfer to the atomic adsorbates.

First-principles study on the electronic, optical, and transport properties of monolayer α- and β-GeSe

DOE PAGES

Xu, Yuanfeng; Zhang, Hao; Shao, Hezhu; ...

2017-12-15

The extraordinary properties and the novel applications of black phosphorene induce the research interest in the monolayer group-IV monochalcogenides. Here using first-principles calculations, we systematically investigate the electronic, transport, and optical properties of monolayer α- and β-GeSe, revealing a direct band gap of 1.61 eV for monolayer α-GeSe and an indirect band gap of 2.47 eV for monolayer β-GeSe. For monolayer β-GeSe, the electronic/hole transport is anisotropic, with an extremely high electron mobility of 2.93×104cm2/Vs along the armchair direction, comparable to that of black phosphorene. However, for β-GeSe, robust band gaps nearly independent of the applied tensile strain along themore » armchair direction are observed. Both monolayer α- and β-GeSe exhibit anisotropic optical absorption in the visible spectrum.« less

Strain-induced band-gap engineering of graphene monoxide and its effect on graphene

NASA Astrophysics Data System (ADS)

Pu, H. H.; Rhim, S. H.; Hirschmugl, C. J.; Gajdardziska-Josifovska, M.; Weinert, M.; Chen, J. H.

2013-02-01

Using first-principles calculations we demonstrate the feasibility of band-gap engineering in two-dimensional crystalline graphene monoxide (GMO), a recently reported graphene-based material with a 1:1 carbon/oxygen ratio. The band gap of GMO, which can be switched between direct and indirect, is tunable over a large range (0-1.35 eV) for accessible strains. Electron and hole transport occurs predominantly along the zigzag and armchair directions (armchair for both) when GMO is a direct- (indirect-) gap semiconductor. A band gap of ˜0.5 eV is also induced in graphene at the K' points for GMO/graphene hybrid systems.

Indigenous Students and Completion of Year 12. Education and Training in an Era of Economic Uncertainty: CEET 13th Annual National Conference

ERIC Educational Resources Information Center

Long, Michael

2009-01-01

The Council of Australian Governments (COAG) has endorsed a "Closing the Gap" agenda designed to improve the lives of Indigenous Australians. The agenda is distilled in a series of targets, one of which is the goal of halving the gap for Indigenous students in Year 12 attainment or equivalent (Certificate II or above) attainment rates by…

Design Principles for the Atomic and Electronic Structure of Halide Perovskite Photovoltaic Materials: Insights from Computation.

PubMed

Berger, Robert F

2018-02-09

In the current decade, perovskite solar cell research has emerged as a remarkably active, promising, and rapidly developing field. Alongside breakthroughs in synthesis and device engineering, halide perovskite photovoltaic materials have been the subject of predictive and explanatory computational work. In this Minireview, we focus on a subset of this computation: density functional theory (DFT)-based work highlighting the ways in which the electronic structure and band gap of this class of materials can be tuned via changes in atomic structure. We distill this body of computational literature into a set of underlying design principles for the band gap engineering of these materials, and rationalize these principles from the viewpoint of band-edge orbital character. We hope that this perspective provides guidance and insight toward the rational design and continued improvement of perovskite photovoltaics. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Energy Literacy: A Natural and Essential Part of a Solutions-Based Approach to Climate Literacy

NASA Astrophysics Data System (ADS)

Inman, M. M.

2011-12-01

As with climate science topics, many Americans have misconceptions or gaps in understanding related to energy topics. Recent literacy efforts are geared to address these gaps in understanding. The U.S. Global Change Research Program's recently published "Energy Literacy: Essential Principles and Fundamental Concepts for Energy Education" offers a welcome complement to the Climate Literacy Essential Principles released in 2008. Research and experience suggest that education, communication and outreach about global climate change and related topics is best done using a solutions-based approach. Energy is a natural and effective topic to frame these solutions around. Used as a framework for designing curricula, Energy Literacy naturally leads to solutions-based approaches to Climate Change education. An inherently interdisciplinary topic, energy education must happen in the context of both the natural and social sciences. The Energy Literacy Essential Principles reflect this and open the door to curriculum that integrates the two.

The Demand for Water Transportation: Application of Discriminant Analysis to Commodities Shipped by Barge and Competing Modes in Ohio River and Arkansas River Areas.

DTIC Science & Technology

1980-08-01

extended to include influence of time in transit, perishability, and uncertainty in market 7Alfred Marshall, Principles of Economics , 9th Edition (McMillan...the Maritime Administration, U.S. Department of Commerce, Washington, D.C. (1974). Marshall, Alfred. Principles of Economics . 9th Edition. :.[cMillian

The quantum universe

NASA Astrophysics Data System (ADS)

Hey, Anthony J. G.; Walters, Patrick

This book provides a descriptive, popular account of quantum physics. The basic topics addressed include: waves and particles, the Heisenberg uncertainty principle, the Schroedinger equation and matter waves, atoms and nuclei, quantum tunneling, the Pauli exclusion principle and the elements, quantum cooperation and superfluids, Feynman rules, weak photons, quarks, and gluons. The applications of quantum physics to astrophyics, nuclear technology, and modern electronics are addressed.

Integration of different data gap filling techniques to facilitate assessment of polychlorinated biphenyls: A proof of principle case study (ASCCT meeting)

EPA Science Inventory

Data gap filling techniques are commonly used to predict hazard in the absence of empirical data. The most established techniques are read-across, trend analysis and quantitative structure-activity relationships (QSARs). Toxic equivalency factors (TEFs) are less frequently used d...

A Modest Proposal for Improving the Education of Reading Teachers. Technical Report No. 487.

ERIC Educational Resources Information Center

Anderson, Richard C.; And Others

A gap exists between talk about teaching that is featured in most preservice teacher education and the working knowledge and problem-solving expertise that characterize skilled teaching. This gap exists because typical teacher training does not embody the principles of modeling, coaching, scaffolding, articulation, and reflection. Three methods…

Understanding and applying principles of social cognition and ...

EPA Pesticide Factsheets

Environmental governance systems are under greater pressure to adapt and to cope with increased social and ecological uncertainty from stressors like climate change. We review principles of social cognition and decision making that shape and constrain how environmental governance systems adapt. We focus primarily on the interplay between key decision makers in society and legal systems. We argue that adaptive governance must overcome three cooperative dilemmas to facilitate adaptation: (1) encouraging collaborative problem solving, (2) garnering social acceptance and commitment, and (3) cultivating a culture of trust and tolerance for change and uncertainty. However, to do so governance systems must cope with biases in people’s decision making that cloud their judgment and create conflict. These systems must also satisfy people’s fundamental needs for self-determination, fairness, and security, ensuring that changes to environmental governance are perceived as legitimate, trustworthy, and acceptable. We discuss the implications of these principles for common governance solutions (e.g., public participation, enforcement) and conclude with methodological recommendations. We outline how scholars can investigate the social cognitive principles involved in cases of adaptive governance. Social-ecological stressors place significant pressure on major societal systems, triggering adaptive reforms in human governance and environmental law. Though potentially benefici

Local perturbations perturb—exponentially-locally

NASA Astrophysics Data System (ADS)

De Roeck, W.; Schütz, M.

2015-06-01

We elaborate on the principle that for gapped quantum spin systems with local interaction, "local perturbations [in the Hamiltonian] perturb locally [the groundstate]." This principle was established by Bachmann et al. [Commun. Math. Phys. 309, 835-871 (2012)], relying on the "spectral flow technique" or "quasi-adiabatic continuation" [M. B. Hastings, Phys. Rev. B 69, 104431 (2004)] to obtain locality estimates with sub-exponential decay in the distance to the spatial support of the perturbation. We use ideas of Hamza et al. [J. Math. Phys. 50, 095213 (2009)] to obtain similarly a transformation between gapped eigenvectors and their perturbations that is local with exponential decay. This allows to improve locality bounds on the effect of perturbations on the low lying states in certain gapped models with a unique "bulk ground state" or "topological quantum order." We also give some estimate on the exponential decay of correlations in models with impurities where some relevant correlations decay faster than one would naively infer from the global gap of the system, as one also expects in disordered systems with a localized groundstate.

First principles examination of electronic structure and optical features of 4H-GaN1-xPx polytype alloys

NASA Astrophysics Data System (ADS)

Laref, A.; Hussain, Z.; Laref, S.; Yang, J. T.; Xiong, Y. C.; Luo, S. J.

2018-04-01

By using first-principles calculations, we compute the electronic band structures and typical aspects of the optical spectra of hexagonally structured GaN1-xPx alloys. Although a type III-V semiconductor, GaP commonly possesses a zinc-blende structure with an indirect band gap; as such, it may additionally form hexagonal polytypes under specific growth conditions. The electronic structures and optical properties are calculated by combining a non-nitride III-V semiconductor and a nitride III-V semiconductor, as GaP and GaN crystallizing in a 4H polytype, with the N composition ranging between x = 0-1. For all studied materials, the energy gap is found to be direct. The optical properties of the hexagonal materials may illustrate the strong polarization dependence owing to the crystalline anisotropy. This investigation for GaN1-xPx alloys is anticipated to supply paramount information for applications in the visible/ultraviolet spectral regions. At a specific concentration, x, these alloys would be exclusively appealing candidates for solar-cell applications.

New horizons in the implementation and research of comprehensive geriatric assessment: knowing, doing and the 'know-do' gap.

PubMed

Gladman, John R F; Conroy, Simon Paul; Ranhoff, Anette Hylen; Gordon, Adam Lee

2016-03-01

In this paper, we outline the relationship between the need to put existing applied health research knowledge into practice (the 'know-do gap') and the need to improve the evidence base (the 'know gap') with respect to the healthcare process used for older people with frailty known as comprehensive geriatric assessment (CGA). We explore the reasons for the know-do gap and the principles of how these barriers to implementation might be overcome. We explore how these principles should affect the conduct of applied health research to close the know gap. We propose that impaired flow of knowledge is an important contributory factor in the failure to implement evidence-based practice in CGA; this could be addressed through specific knowledge mobilisation techniques. We describe that implementation failures are also produced by an inadequate evidence base that requires the co-production of research, addressing not only effectiveness but also the feasibility and acceptability of new services, the educational needs of practitioners, the organisational requirements of services, and the contribution made by policy. Only by tackling these issues in concert and appropriate proportion, will the know and know-do gaps for CGA be closed. © The Author 2016. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A fully Bayesian method for jointly fitting instrumental calibration and X-ray spectral models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Jin; Yu, Yaming; Van Dyk, David A.

2014-10-20

Owing to a lack of robust principled methods, systematic instrumental uncertainties have generally been ignored in astrophysical data analysis despite wide recognition of the importance of including them. Ignoring calibration uncertainty can cause bias in the estimation of source model parameters and can lead to underestimation of the variance of these estimates. We previously introduced a pragmatic Bayesian method to address this problem. The method is 'pragmatic' in that it introduced an ad hoc technique that simplified computation by neglecting the potential information in the data for narrowing the uncertainty for the calibration product. Following that work, we use amore » principal component analysis to efficiently represent the uncertainty of the effective area of an X-ray (or γ-ray) telescope. Here, however, we leverage this representation to enable a principled, fully Bayesian method that coherently accounts for the calibration uncertainty in high-energy spectral analysis. In this setting, the method is compared with standard analysis techniques and the pragmatic Bayesian method. The advantage of the fully Bayesian method is that it allows the data to provide information not only for estimation of the source parameters but also for the calibration product—here the effective area, conditional on the adopted spectral model. In this way, it can yield more accurate and efficient estimates of the source parameters along with valid estimates of their uncertainty. Provided that the source spectrum can be accurately described by a parameterized model, this method allows rigorous inference about the effective area by quantifying which possible curves are most consistent with the data.« less

Principled Practical Knowledge: Not a Bridge but a Ladder

ERIC Educational Resources Information Center

Bereiter, Carl

2014-01-01

The much-lamented gap between theory and practice in education cannot be filled by practical knowledge alone or by explanatory knowledge alone. Principled practical knowledge (PPK) is a type of knowledge that has characteristics of both practical know-how and scientific theory. Like basic scientific theory, PPK meets standards of explanatory…

Science Goals in Radiation Protection for Exploration

NASA Technical Reports Server (NTRS)

Cucinotta, Francs A.

2008-01-01

Space radiation presents major challenges to future missions to the Earth s moon or Mars. Health risks of concern include cancer, degenerative and performance risks to the central nervous system, heart and lens, and the acute radiation syndromes. The galactic cosmic rays (GCR) contain high energy and charge (HZE) nuclei, which have been shown to cause qualitatively distinct biological damage compared to terresterial radiation, such as X-rays or gamma-rays, causing risk estimates to be highly uncertain. The biological effects of solar particle events (SPE) are similar to terresterial radiation except for their biological dose-rate modifiers; however the onset and size of SPEs are difficult to predict. The high energies of GCR reduce the effectiveness of shielding, while SPE s can be shielded however the current gap in radiobiological knowledge hinders optimization. Methods used to project risks on Earth must be modified because of the large uncertainties in projecting health risks from space radiation, and thus impact mission requirements and costs. We describe NASA s unique approach to radiation safety that applies probabilistic risk assessments and uncertainty based criteria within the occupational health program for astronauts and to mission design. The two terrestrial criteria of a point estimate of maximum acceptable level of risk and application of the principle of As Low As Reasonably Achievable (ALARA) are supplemented by a third requirement that protects against risk projection uncertainties using the upper 95% confidence level (CL) in radiation risk projection models. Exploration science goals in radiation protection are centered on ground-based research to achieve the necessary biological knowledge, and in the development of new technologies to improve SPE monitoring and optimize shielding. Radiobiology research is centered on a ground based program investigating the radiobiology of high-energy protons and HZE nuclei at the NASA Space Radiation Laboratory (NSRL) located at DoE s Brookhaven National Laboratory in Upton, NY. We describe recent NSRL results that are closing the knowledge gap in HZE radiobiology and improving exploration risk estimates. Linking probabilistic risk assessment to research goals makes it possible to express risk management objectives in terms of quantitative metrics, which include the number of days in space without exceeding a given risk level within well defined confidence limits, and probabilistic assessments of the effectiveness of design trade spaces such as material type, mass, solar cycle, crew selection criteria, and biological countermeasures. New research in SPE alert and risk assessment, individual radiation sensitivity, and biological countermeasure development are described.

Prevention of cardiovascular diseases.

PubMed

Hobbs, F D Richard

2015-10-12

Cardiovascular disease (CVD) is the most important cause of premature death and disability globally. Much is known of the main aetiological risk factors, including elevated blood pressure, dyslipidaemia and smoking, with a raft of additional risks of increasing prevalence, such as obesity and diabetes. Furthermore, some of the most secure evidence-based management strategies in healthcare relate to interventions that modify risk. Yet major gaps remain in the implementation of such evidence, summarized in international guideline recommendations. Some of this gap relates to knowledge deficits amongst clinicians, but also to continued uncertainties over interpretation of the evidence base and areas where data are less available. This article collection in BMC Medicine seeks to offer reflections in each of these areas of uncertainty, spanning issues of better diagnosis, areas of controversy and glimpses of potentially potent future interventions in the prevention of CVD.

Uncertainty for Part Density Determination: An Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valdez, Mario Orlando

2016-12-14

Accurate and precise density measurements by hydrostatic weighing requires the use of an analytical balance, configured with a suspension system, to both measure the weight of a part in water and in air. Additionally, the densities of these liquid media (water and air) must be precisely known for the part density determination. To validate the accuracy and precision of these measurements, uncertainty statements are required. The work in this report is a revision of an original report written more than a decade ago, specifically applying principles and guidelines suggested by the Guide to the Expression of Uncertainty in Measurement (GUM)more » for determining the part density uncertainty through sensitivity analysis. In this work, updated derivations are provided; an original example is revised with the updated derivations and appendix, provided solely to uncertainty evaluations using Monte Carlo techniques, specifically using the NIST Uncertainty Machine, as a viable alternative method.« less

Research Directions for Cyber Experimentation: Workshop Discussion Analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeWaard, Elizabeth; Deccio, Casey; Fritz, David Jakob

Sandia National Laboratories hosted a workshop on August 11, 2017 entitled "Research Directions for Cyber Experimentation," which focused on identifying and addressing research gaps within the field of cyber experimentation , particularly emulation testbeds . This report mainly documents the discussion toward the end of the workshop, which included research gaps such as developing a sustainable research infrastructure, exp anding cyber experimentation, and making the field more accessible to subject matter experts who may not have a background in computer science . Other gaps include methodologies for rigorous experimentation, validation, and uncertainty quantification, which , if addressed, also have themore » potential to bridge the gap between cyber experimentation and cyber engineering. Workshop attendees presented various ways to overcome these research gaps, however the main conclusion for overcoming these gaps is better commun ication through increased workshops, conferences, email lists, and slack chann els, among other opportunities.« less

Momentum dependence of the superconducting gap and in-gap states in MgB 2 multiband superconductor

DOE PAGES

Mou, Daixiang; Jiang, Rui; Taufour, Valentin; ...

2015-06-29

We use tunable laser-based angle-resolved photoemission spectroscopy to study the electronic structure of the multiband superconductor MgB 2. These results form the baseline for detailed studies of superconductivity in multiband systems. We find that the magnitude of the superconducting gap on both σ bands follows a BCS-like variation with temperature with Δ 0 ~ 7meV. Furthermore, the value of the gap is isotropic within experimental uncertainty and in agreement with a pure s-wave pairing symmetry. We observe in-gap states confined to k F of the σ band that occur at some locations of the sample surface. As a result, themore » energy of this excitation, ~ 3 meV, was found to be somewhat larger than the previously reported gap on π Fermi sheet and therefore we cannot exclude the possibility of interband scattering as its origin.« less

Casuistry and principlism: the convergence of method in biomedical ethics.

PubMed

Kuczewski, M

1998-12-01

Casuistry and principlism are two of the leading contenders to be considered the methodology of bioethics. These methods may be incommensurable since the former emphasizes the examination of cases while the latter focuses on moral principles. Conversely, since both analyze cases in terms of mid-level principles, there is hope that these methods may be reconcilable or complementary. I analyze the role of principles in each and thereby show that these theories are virtually identical when interpreted in a certain light. That is, if the gaps in each method are filled by a concept of judgment or Aristotelian practical wisdom, these methods converge.

Planck Constant Determination from Power Equivalence

NASA Astrophysics Data System (ADS)

Newell, David B.

2000-04-01

Equating mechanical to electrical power links the kilogram, the meter, and the second to the practical realizations of the ohm and the volt derived from the quantum Hall and the Josephson effects, yielding an SI determination of the Planck constant. The NIST watt balance uses this power equivalence principle, and in 1998 measured the Planck constant with a combined relative standard uncertainty of 8.7 x 10-8, the most accurate determination to date. The next generation of the NIST watt balance is now being assembled. Modification to the experimental facilities have been made to reduce the uncertainty components from vibrations and electromagnetic interference. A vacuum chamber has been installed to reduce the uncertainty components associated with performing the experiment in air. Most of the apparatus is in place and diagnostic testing of the balance should begin this year. Once a combined relative standard uncertainty of one part in 10-8 has been reached, the power equivalence principle can be used to monitor the possible drift in the artifact mass standard, the kilogram, and provide an accurate alternative definition of mass in terms of fundamental constants. *Electricity Division, Electronics and Electrical Engineering Laboratory, Technology Administration, U.S. Department of Commerce. Contribution of the National Institute of Standards and Technology, not subject to copyright in the U.S.

Task Design for Ways of Working: Making Distinctions in Teaching and Learning Mathematics

ERIC Educational Resources Information Center

Coles, Alf; Brown, Laurinda

2016-01-01

A problem identified in the literature around task design is the persistence of a gap between teacher intention and student activity. We show how principles designed around the making of distinctions and having an explicit language of mathematical thinking can eliminate the "gap" by guiding teacher planning, teacher actions in the…

Element budgets in an Arctic mesocosm CO2 perturbation study

NASA Astrophysics Data System (ADS)

Czerny, J.; Schulz, K. G.; Boxhammer, T.; Bellerby, R. G. J.; Büdenbender, J.; Engel, A.; Krug, S. A.; Ludwig, A.; Nachtigall, K.; Nondal, G.; Niehoff, B.; Siljakova, A.; Riebesell, U.

2012-08-01

Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining the temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental budgets. In practice, attempts to budget mesocosm enclosures are often hampered by uncertainties in some of the measured pools and fluxes, in particular due to uncertainties in constraining air/sea gas exchange, particle sinking, and wall growth. In an Arctic mesocosm study on ocean acidification using KOSMOS (Kiel Off-Shore Mesocosms for future Ocean Simulation) all relevant element pools and fluxes of carbon, nitrogen and phosphorus were measured, using an improved experimental design intended to narrow down some of the mentioned uncertainties. Water column concentrations of particulate and dissolved organic and inorganic constituents were determined daily. New approaches for quantitative estimates of material sinking to the bottom of the mesocosms and gas exchange in 48 h temporal resolution, as well as estimates of wall growth were developed to close the gaps in element budgets. Future elevated pCO2 was found to enhance net autotrophic community carbon uptake in 2 of the 3 experimental phases but did not significantly affect particle elemental composition. Enhanced carbon consumption appears to result in accumulation of dissolved organic compounds under nutrient recycling summer conditions. This carbon over-consumption effect becomes evident from budget calculations, but was too small to be resolved by direct measurements of dissolved organics. The out-competing of large diatoms by comparatively small algae in nutrient uptake caused reduced production rates under future ocean CO2 conditions in the end of the experiment. This CO2 induced shift away from diatoms towards smaller phytoplankton and enhanced cycling of dissolved organics was pushing the system towards a retention type food chain with overall negative effects on export potential.

Particles, Waves, and the Interpretation of Quantum Mechanics

ERIC Educational Resources Information Center

Christoudouleas, N. D.

1975-01-01

Presents an explanation, without mathematical equations, of the basic principles of quantum mechanics. Includes wave-particle duality, the probability character of the wavefunction, and the uncertainty relations. (MLH)

The equivalence principle in a quantum world

NASA Astrophysics Data System (ADS)

Bjerrum-Bohr, N. E. J.; Donoghue, John F.; El-Menoufi, Basem Kamal; Holstein, Barry R.; Planté, Ludovic; Vanhove, Pierre

2015-09-01

We show how modern methods can be applied to quantum gravity at low energy. We test how quantum corrections challenge the classical framework behind the equivalence principle (EP), for instance through introduction of nonlocality from quantum physics, embodied in the uncertainty principle. When the energy is small, we now have the tools to address this conflict explicitly. Despite the violation of some classical concepts, the EP continues to provide the core of the quantum gravity framework through the symmetry — general coordinate invariance — that is used to organize the effective field theory (EFT).

The Sapir-Whorf hypothesis and inference under uncertainty.

PubMed

Regier, Terry; Xu, Yang

2017-11-01

The Sapir-Whorf hypothesis holds that human thought is shaped by language, leading speakers of different languages to think differently. This hypothesis has sparked both enthusiasm and controversy, but despite its prominence it has only occasionally been addressed in computational terms. Recent developments support a view of the Sapir-Whorf hypothesis in terms of probabilistic inference. This view may resolve some of the controversy surrounding the Sapir-Whorf hypothesis, and may help to normalize the hypothesis by linking it to established principles that also explain other phenomena. On this view, effects of language on nonlinguistic cognition or perception reflect standard principles of inference under uncertainty. WIREs Cogn Sci 2017, 8:e1440. doi: 10.1002/wcs.1440 For further resources related to this article, please visit the WIREs website. © 2017 Wiley Periodicals, Inc.

Measuring the Newtonian constant of gravitation with a differential free-fall gradiometer: A feasibility study

NASA Astrophysics Data System (ADS)

Rothleitner, Christian; Francis, Olivier

2014-04-01

An original setup is presented to measure the Newtonian Constant of Gravitation G. It is based on the same principle as used in ballistic absolute gravimeters. The differential acceleration of three simultaneously freely falling test masses is measured in order to determine G. In this paper, a description of the experimental setup is presented. A detailed uncertainty budget estimates the relative uncertainty to be of the order of 5.3 × 10-4, however with some improvements a relative uncertainty in G of one part in 104 could be feasible.

Position-momentum uncertainty relations in the presence of quantum memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furrer, Fabian, E-mail: furrer@eve.phys.s.u-tokyo.ac.jp; Berta, Mario; Institute for Theoretical Physics, ETH Zurich, Wolfgang-Pauli-Str. 27, 8093 Zürich

2014-12-15

A prominent formulation of the uncertainty principle identifies the fundamental quantum feature that no particle may be prepared with certain outcomes for both position and momentum measurements. Often the statistical uncertainties are thereby measured in terms of entropies providing a clear operational interpretation in information theory and cryptography. Recently, entropic uncertainty relations have been used to show that the uncertainty can be reduced in the presence of entanglement and to prove security of quantum cryptographic tasks. However, much of this recent progress has been focused on observables with only a finite number of outcomes not including Heisenberg’s original setting ofmore » position and momentum observables. Here, we show entropic uncertainty relations for general observables with discrete but infinite or continuous spectrum that take into account the power of an entangled observer. As an illustration, we evaluate the uncertainty relations for position and momentum measurements, which is operationally significant in that it implies security of a quantum key distribution scheme based on homodyne detection of squeezed Gaussian states.« less

Steering the measured uncertainty under decoherence through local PT -symmetric operations

NASA Astrophysics Data System (ADS)

Shi, Wei-Nan; Wang, Dong; Sun, Wen-Yang; Ming, Fei; Huang, Ai-Jun; Ye, Liu

2018-07-01

The uncertainty principle is viewed as one of the appealing properties in the context of quantum mechanics, which intrinsically offers a lower bound with regard to the measurement outcomes of a pair of incompatible observables within a given system. In this letter, we attempt to observe entropic uncertainty in the presence of quantum memory under different local noisy channels. To be specific, we develop the dynamics of the measured uncertainty under local bit-phase-flipping (unital) and depolarization (nonunital) noise, respectively, and attractively put forward an effective strategy to manipulate its magnitude of the uncertainty of interest by means of parity-time symmetric (-symmetric) operations on the subsystem to be measured. It is interesting to find that there exist different evolution characteristics of the uncertainty in the channels considered here, i.e. the monotonic behavior in the nonunital channels, and the non-monotonic behavior in the unital channels. Moreover, the amount of the measured uncertainty can be reduced to some degree by properly modulating the -symmetric operations.

Assessing and reporting uncertainties in dietary exposure analysis: Mapping of uncertainties in a tiered approach.

PubMed

Kettler, Susanne; Kennedy, Marc; McNamara, Cronan; Oberdörfer, Regina; O'Mahony, Cian; Schnabel, Jürgen; Smith, Benjamin; Sprong, Corinne; Faludi, Roland; Tennant, David

2015-08-01

Uncertainty analysis is an important component of dietary exposure assessments in order to understand correctly the strength and limits of its results. Often, standard screening procedures are applied in a first step which results in conservative estimates. If through those screening procedures a potential exceedance of health-based guidance values is indicated, within the tiered approach more refined models are applied. However, the sources and types of uncertainties in deterministic and probabilistic models can vary or differ. A key objective of this work has been the mapping of different sources and types of uncertainties to better understand how to best use uncertainty analysis to generate more realistic comprehension of dietary exposure. In dietary exposure assessments, uncertainties can be introduced by knowledge gaps about the exposure scenario, parameter and the model itself. With this mapping, general and model-independent uncertainties have been identified and described, as well as those which can be introduced and influenced by the specific model during the tiered approach. This analysis identifies that there are general uncertainties common to point estimates (screening or deterministic methods) and probabilistic exposure assessment methods. To provide further clarity, general sources of uncertainty affecting many dietary exposure assessments should be separated from model-specific uncertainties. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Uncertainty during breast diagnostic evaluation: state of the science.

PubMed

Montgomery, Mariann

2010-01-01

To present the state of the science on uncertainty in relationship to the experiences of women undergoing diagnostic evaluation for suspected breast cancer. Published articles from Medline, CINAHL, PubMED, and PsycINFO from 1983-2008 using the following key words: breast biopsy, mammography, uncertainty, reframing, inner strength, and disruption. Fifty research studies were examined with all reporting the presence of anxiety persisting throughout the diagnostic evaluation until certitude is achieved through the establishment of a definitive diagnosis. Indirect determinants of uncertainty for women undergoing breast diagnostic evaluation include measures of anxiety, depression, social support, emotional responses, defense mechanisms, and the psychological impact of events. Understanding and influencing the uncertainty experience have been suggested to be key in relieving psychosocial distress and positively influencing future screening behaviors. Several studies examine correlational relationships among anxiety, selection of coping methods, and demographic factors that influence uncertainty. A gap exists in the literature with regard to the relationship of inner strength and uncertainty. Nurses can be invaluable in assisting women in coping with the uncertainty experience by providing positive communication and support. Nursing interventions should be designed and tested for their effects on uncertainty experienced by women undergoing a breast diagnostic evaluation.

Quantitative risk assessment of CO2 transport by pipelines--a review of uncertainties and their impacts.

PubMed

Koornneef, Joris; Spruijt, Mark; Molag, Menso; Ramírez, Andrea; Turkenburg, Wim; Faaij, André

2010-05-15

A systematic assessment, based on an extensive literature review, of the impact of gaps and uncertainties on the results of quantitative risk assessments (QRAs) for CO(2) pipelines is presented. Sources of uncertainties that have been assessed are: failure rates, pipeline pressure, temperature, section length, diameter, orifice size, type and direction of release, meteorological conditions, jet diameter, vapour mass fraction in the release and the dose-effect relationship for CO(2). A sensitivity analysis with these parameters is performed using release, dispersion and impact models. The results show that the knowledge gaps and uncertainties have a large effect on the accuracy of the assessed risks of CO(2) pipelines. In this study it is found that the individual risk contour can vary between 0 and 204 m from the pipeline depending on assumptions made. In existing studies this range is found to be between <1m and 7.2 km. Mitigating the relevant risks is part of current practice, making them controllable. It is concluded that QRA for CO(2) pipelines can be improved by validation of release and dispersion models for high-pressure CO(2) releases, definition and adoption of a universal dose-effect relationship and development of a good practice guide for QRAs for CO(2) pipelines. Copyright (c) 2009 Elsevier B.V. All rights reserved.

PARTNERING TO IMPROVE HUMAN EXPOSURE METHODS

EPA Science Inventory

Methods development research is an application-driven scientific area that addresses programmatic needs. The goals are to reduce measurement uncertainties, address data gaps, and improve existing analytical procedures for estimating human exposures. Partnerships have been develop...

Bayesian Model Averaging of Artificial Intelligence Models for Hydraulic Conductivity Estimation

NASA Astrophysics Data System (ADS)

Nadiri, A.; Chitsazan, N.; Tsai, F. T.; Asghari Moghaddam, A.

2012-12-01

This research presents a Bayesian artificial intelligence model averaging (BAIMA) method that incorporates multiple artificial intelligence (AI) models to estimate hydraulic conductivity and evaluate estimation uncertainties. Uncertainty in the AI model outputs stems from error in model input as well as non-uniqueness in selecting different AI methods. Using one single AI model tends to bias the estimation and underestimate uncertainty. BAIMA employs Bayesian model averaging (BMA) technique to address the issue of using one single AI model for estimation. BAIMA estimates hydraulic conductivity by averaging the outputs of AI models according to their model weights. In this study, the model weights were determined using the Bayesian information criterion (BIC) that follows the parsimony principle. BAIMA calculates the within-model variances to account for uncertainty propagation from input data to AI model output. Between-model variances are evaluated to account for uncertainty due to model non-uniqueness. We employed Takagi-Sugeno fuzzy logic (TS-FL), artificial neural network (ANN) and neurofuzzy (NF) to estimate hydraulic conductivity for the Tasuj plain aquifer, Iran. BAIMA combined three AI models and produced better fitting than individual models. While NF was expected to be the best AI model owing to its utilization of both TS-FL and ANN models, the NF model is nearly discarded by the parsimony principle. The TS-FL model and the ANN model showed equal importance although their hydraulic conductivity estimates were quite different. This resulted in significant between-model variances that are normally ignored by using one AI model.

Some Aspects of the Implementation of the Principle of Transparency in Russian Universities: Research, Experience, Perspectives

ERIC Educational Resources Information Center

Egorov, Evgeny Evgenievich; Lebedev?, Tatiana Evgenievna; Bulganina, Svetlana Viktorovna; Vasilyeva, Lyudmila Ivanovna

2015-01-01

The aim of this study is to identify achieved successes, existing gaps and possible prospects of implementing the principle of transparency by Russian universities. It was focused upon the information transparency of educational activities from the perspective of legal requirements and interests of applicants and university students. The analysis…

A Critical Praxis: Narrowing the Gap between Identity, Theory, and Practice

ERIC Educational Resources Information Center

Waller, Laurel; Wethers, Kinsey; De Costa, Peter I.

2017-01-01

Praxis is the balance of pedagogical theory and practice. This literature review explores praxis from a critical lens in terms of identity for both students and teachers. The authors center their framework on Hawkins and Norton's (2009) five principles for critical language teaching. The first principle relates to the situated nature of the…

Questions Students Ask: Beta Decay.

ERIC Educational Resources Information Center

Koss, Jordan; Hartt, Kenneth

1988-01-01

Answers a student's question about the emission of a positron from a nucleus. Discusses the problem from the aspects of the uncertainty principle, beta decay, the Fermi Theory, and modern physics. (YP)

The redoubtable ecological periodic table

EPA Science Inventory

Ecological periodic tables are repositories of reliable information on quantitative, predictably recurring (periodic) habitat–community patterns and their uncertainty, scaling and transferability. Their reliability derives from their grounding in sound ecological principle...

Computer-Aided Experiment Planning toward Causal Discovery in Neuroscience.

PubMed

Matiasz, Nicholas J; Wood, Justin; Wang, Wei; Silva, Alcino J; Hsu, William

2017-01-01

Computers help neuroscientists to analyze experimental results by automating the application of statistics; however, computer-aided experiment planning is far less common, due to a lack of similar quantitative formalisms for systematically assessing evidence and uncertainty. While ontologies and other Semantic Web resources help neuroscientists to assimilate required domain knowledge, experiment planning requires not only ontological but also epistemological (e.g., methodological) information regarding how knowledge was obtained. Here, we outline how epistemological principles and graphical representations of causality can be used to formalize experiment planning toward causal discovery. We outline two complementary approaches to experiment planning: one that quantifies evidence per the principles of convergence and consistency, and another that quantifies uncertainty using logical representations of constraints on causal structure. These approaches operationalize experiment planning as the search for an experiment that either maximizes evidence or minimizes uncertainty. Despite work in laboratory automation, humans must still plan experiments and will likely continue to do so for some time. There is thus a great need for experiment-planning frameworks that are not only amenable to machine computation but also useful as aids in human reasoning.

Conservation in the face of climate change: The roles of alternative models, monitoring, and adaptation in confronting and reducing uncertainty

USGS Publications Warehouse

Conroy, M.J.; Runge, M.C.; Nichols, J.D.; Stodola, K.W.; Cooper, R.J.

2011-01-01

The broad physical and biological principles behind climate change and its potential large scale ecological impacts on biota are fairly well understood, although likely responses of biotic communities at fine spatio-temporal scales are not, limiting the ability of conservation programs to respond effectively to climate change outside the range of human experience. Much of the climate debate has focused on attempts to resolve key uncertainties in a hypothesis-testing framework. However, conservation decisions cannot await resolution of these scientific issues and instead must proceed in the face of uncertainty. We suggest that conservation should precede in an adaptive management framework, in which decisions are guided by predictions under multiple, plausible hypotheses about climate impacts. Under this plan, monitoring is used to evaluate the response of the system to climate drivers, and management actions (perhaps experimental) are used to confront testable predictions with data, in turn providing feedback for future decision making. We illustrate these principles with the problem of mitigating the effects of climate change on terrestrial bird communities in the southern Appalachian Mountains, USA. ?? 2010 Elsevier Ltd.

Using info-Gap Decision Theory for Water Resources Planning Under Severe Uncertainty

NASA Astrophysics Data System (ADS)

Korteling, B.; Brazier, R.; Kapelan, Z.; Dessai, S.

2012-12-01

Water resource managers are required to develop comprehensive water resource plans based on severely uncertain information of the effects of climate change on local hydrology and future socio-economic changes on localised demand. In England and Wales, current water resource planning methodologies include a headroom estimation process that quantifies uncertainty based on only one point of an assumed range of deviations from the expected climate and projected demand 25 years into the future. There are many situations where there is not enough knowledge to be able to estimate a representative probability of occurrence, or to be confident that the tails of an assumed probability distribution will not exhibit unexpected skewness, or that the kurtosis of a distribution differs from the norm. These situations can be considered severely uncertain. Information-Gap decision theory offers a method to sample a wider range of uncertainty than with traditional methods, and as a result, compare the robustness of various water resource management options under conditions of severe uncertainty. A more robust management option is one that delivers the same level of performance as other options at higher levels of uncertainty. A case study is based on a Water Supply Area that encompasses the county of Cornwall in southwest England containing 17 reservoirs and 19 demand nodes. The performance success of management options are evaluated primarily by measures of water availability including a reservoir risk measure that tests the probability and magnitude that strategic reservoir storage levels fall below the drought management curve under adverse conditions and also a safety margin deficit that tests how quickly reservoir levels can return to optimum operating levels in favourable conditions. Multi-Criteria Decision Analysis (MCDA) is used to test the effectiveness of different management options with different weightings for metrics other than water availability including; capital and operating costs, costs to customers, carbon emissions, environmental impact and social acceptability. Findings show that beyond the uncertainty range explored with the traditional headroom method, preference reversals can occur, i.e. some management options that underperform at lower uncertainties, outperform at higher levels of uncertainty. This study also shows that when 50% or more of the population adopts demand side management, efficiency related measures and innovative options such as rainwater collection can perform equally well or better than some supply side options. The additional use of MCDA shifts the focus away from reservoir expansion options that perform best with respect to water availability, to combined strategies that include innovative demand side management actions of rainwater collection and greywater reuse as well as efficiency measures and additional regional transfers. This research illustrates how an Info-Gap based approach can offer a comprehensive picture of potential supply/demand futures and a rich variety of information to support adaptive management of water systems under severe uncertainty.

Risk assessment of pesticides and other stressors in bees: Principles, data gaps and perspectives from the European Food Safety Authority.

PubMed

Rortais, Agnès; Arnold, Gérard; Dorne, Jean-Lou; More, Simon J; Sperandio, Giorgio; Streissl, Franz; Szentes, Csaba; Verdonck, Frank

2017-06-01

Current approaches to risk assessment in bees do not take into account co-exposures from multiple stressors. The European Food Safety Authority (EFSA) is deploying resources and efforts to move towards a holistic risk assessment approach of multiple stressors in bees. This paper describes the general principles of pesticide risk assessment in bees, including recent developments at EFSA dealing with risk assessment of single and multiple pesticide residues and biological hazards. The EFSA Guidance Document on the risk assessment of plant protection products in bees highlights the need for the inclusion of an uncertainty analysis, other routes of exposures and multiple stressors such as chemical mixtures and biological agents. The EFSA risk assessment on the survival, spread and establishment of the small hive beetle, Aethina tumida, an invasive alien species, is provided with potential insights for other bee pests such as the Asian hornet, Vespa velutina. Furthermore, data gaps are identified at each step of the risk assessment, and recommendations are made for future research that could be supported under the framework of Horizon 2020. Finally, the recent work conducted at EFSA is presented, under the overarching MUST-B project ("EU efforts towards the development of a holistic approach for the risk assessment on MUltiple STressors in Bees") comprising a toolbox for harmonised data collection under field conditions and a mechanistic model to assess effects from pesticides and other stressors such as biological agents and beekeeping management practices, at the colony level and in a spatially complex landscape. Future perspectives at EFSA include the development of a data model to collate high quality data to calibrate and validate the model to be used as a regulatory tool. Finally, the evidence collected within the framework of MUST-B will support EFSA's activities on the development of a holistic approach to the risk assessment of multiple stressors in bees. In conclusion, EFSA calls for collaborative action at the EU level to establish a common and open access database to serve multiple purposes and different stakeholders. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Measurements of Acceleration Due to Gravity.

ERIC Educational Resources Information Center

Crummett, Bill

1990-01-01

The principle means by which g has been measured are summarized. Discussed are "Kater's Reversible Pendulum," falling rules, and interferometry methods. Types of corrections and various sources of uncertainty are considered. (CW)

Planning for robust reserve networks using uncertainty analysis

USGS Publications Warehouse

Moilanen, A.; Runge, M.C.; Elith, Jane; Tyre, A.; Carmel, Y.; Fegraus, E.; Wintle, B.A.; Burgman, M.; Ben-Haim, Y.

2006-01-01

Planning land-use for biodiversity conservation frequently involves computer-assisted reserve selection algorithms. Typically such algorithms operate on matrices of species presence?absence in sites, or on species-specific distributions of model predicted probabilities of occurrence in grid cells. There are practically always errors in input data?erroneous species presence?absence data, structural and parametric uncertainty in predictive habitat models, and lack of correspondence between temporal presence and long-run persistence. Despite these uncertainties, typical reserve selection methods proceed as if there is no uncertainty in the data or models. Having two conservation options of apparently equal biological value, one would prefer the option whose value is relatively insensitive to errors in planning inputs. In this work we show how uncertainty analysis for reserve planning can be implemented within a framework of information-gap decision theory, generating reserve designs that are robust to uncertainty. Consideration of uncertainty involves modifications to the typical objective functions used in reserve selection. Search for robust-optimal reserve structures can still be implemented via typical reserve selection optimization techniques, including stepwise heuristics, integer-programming and stochastic global search.

Heisenberg Uncertainty and the Allowable Masses of the Up Quark and Down Quark

NASA Astrophysics Data System (ADS)

Orr, Brian

2004-05-01

A possible explanation for the inability to attain deterministic measurements of an elementary particle's energy, as given by the Heisenberg Uncertainty Principle, manifests itself in an interesting anthropic consequent of Andrei Linde's Self-reproducing Inflationary Multiverse model. In Linde's model, the physical laws and constants that govern our universe adopt other values in other universes, due to variable Higgs fields. While the physics in our universe allow for the advent of life and consciousness, the physics necessary for life are not likely to exist in other universes -- Linde demonstrates this through a kind of Darwinism for universes. Our universe, then, is unique. But what are the physical laws and constants that make our universe what it is? Craig Hogan identifies five physical constants that are not bound by symmetry. Fine-tuning these constants gives rise to the basic behavior and structures of the universe. Three of the non-symmetric constants are fermion masses: the up quark mass, the down quark mass, and the electron mass. I will explore Linde's and Hogan's works by comparing the amount of uncertainty in quark masses, as calculated from the Heisenberg Uncertainty Principle, to the range of quark mass values consistent with our observed universe. Should the fine-tuning of the up quark and down quark masses be greater than the range of Heisenberg uncertainties in their respective masses (as I predict, due to quantum tunneling), then perhaps there is a correlation between the measured Heisenberg uncertainty in quark masses and the fine-tuning of masses required for our universe to be as it is. Hogan; "Why the Universe is Just So;" Reviews of Modern Physics; Issue 4; Vol. 72; pg. 1149-1161; Oct. 2000 Linde, "The Self-Reproducing Inflationary Universe;" Scientific American; No. 5; Vol. 271; pg. 48-55; Nov. 1994

A first-principles study of impurity effects on monolayer MoS2: bandgap dominated by donor impurities

NASA Astrophysics Data System (ADS)

Zhang, Hua; Zhou, Wenzhe; Yang, Zhixiong; Wu, Shoujian; Ouyang, Fangping; Xu, Hui

2017-12-01

Based on the first principles calculation, the electrical properties and optical properties of monolayer molybdenum disulfide (MoS2) substitutionally doped by the VB and VIIB transition metal atoms (V, Nb, Ta, Mn, Tc, Re) were investigated. It is found that n-type doping or p-type doping tunes the Fermi level into the conduction band or the valence band respectively, leading to the degenerate semiconductor, while the compensatorily doped systems where the number of valence electrons is not alerted remain direct band gap ranging from 0.958 eV to 1.414 eV. According to the analysis on densities of states, the LUMO orbitals of donor impurities play the crucial role in band gap tuning. Hence, the band gap and optical properties of doped MoS2 are dominated by the species of the donor. Due to the reduction of the band gap, doped MoS2 have a lower threshold energy of photon absorption and an enhanced absorption in near infrared region. These results provide a significant guidance for the design of new 2D optoelectronic materials based on transition metal disulfide.

Sulfur-doped Graphene Nanoribbons with a Sequence of Distinct Band Gaps

NASA Astrophysics Data System (ADS)

Du, Shi-Xuan; Zhang, Yan-Fang; Zhang, Yi; Berger, Reinhard; Feng, Xinliang; Mullen, Klaus; Lin, Xiao; Zhang, Yu-Yang; Pantelides, Sokrates T.; Gao, Hong-Jun

Unlike free-standing graphene, graphene nanoribbons (GNRs) can possess semiconducting band gap. However, achieving such control has been a major challenge in the fabrication of GNRs. Chevron-type GNRs were recently achieved by surface-assisted polymerization of pristine or N-substituted oligophenylene monomers. By mixing two different monomers, GNR heterojunctions can in principle be fabricated. Here we report fabrication and characterization of chevron-type GNRs by using sulfur-substituted oligophenylene monomers to achieve GNRs and related heterostructures for the first time. Importantly, our first-principles calculations show that the band gaps of GNRs can be tailored by different S configurations in cyclodehydrogenated isomers through debromination and intramolecular cyclodehydrogenation. This feature should open up new avenues to create multiple GNR heterojunctions by engineering the sulfur configurations. These predictions have been confirmed by Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS). The unusual sequence of intraribbon heterojunctions may be useful for nanoscale optoelectronic applications based on quantum dots

First principles study of the electronic properties and band gap modulation of two-dimensional phosphorene monolayer: Effect of strain engineering

NASA Astrophysics Data System (ADS)

Phuc, Huynh V.; Hieu, Nguyen N.; Ilyasov, Victor V.; Phuong, Le T. T.; Nguyen, Chuong V.

2018-06-01

The effect of strain on the structural and electronic properties of monolayer phosphorene is studied by using first-principle calculations based on the density functional theory. The intra- and inter-bond length and bond angle for monolayer phosphorene is also evaluated. The intra- and inter-bond length and the bond angle for phosphorene show an opposite tendency under different directions of the applied strain. At the equilibrium state, monolayer phosphorene is a semiconductor with a direct band gap at the Γ-point of 0.91 eV. A direct-indirect band gap transition is found in monolayer phosphorene when both the compression and tensile strain are simultaneously applied along both zigzag and armchair directions. Under the applied compression strain, a semiconductor-metal transition for monolayer phosphorene is observed at -13% and -10% along armchair and zigzag direction, respectively. The direct-indirect and phase transition will largely constrain application of monolayer phosphorene to electronic and optical devices.

Non-Dirac Chern insulators with large band gaps and spin-polarized edge states.

PubMed

Xue, Y; Zhang, J Y; Zhao, B; Wei, X Y; Yang, Z Q

2018-05-10

Based on first-principles calculations and k·p models, we demonstrate that PbC/MnSe heterostructures are a non-Dirac type of Chern insulator with very large band gaps (244 meV) and exotically half-metallic edge states, providing the possibilities of realizing very robust, completely spin polarized, and dissipationless spintronic devices from the heterostructures. The achieved extraordinarily large nontrivial band gap can be ascribed to the contribution of the non-Dirac type electrons (composed of px and py) and the very strong atomic spin-orbit coupling (SOC) interaction of the heavy Pb element in the system. Surprisingly, the band structures are found to be sensitive to the different exchange and correlation functionals adopted in the first-principles calculations. Chern insulators with various mechanisms are acquired from them. These discoveries show that the predicted nontrivial topology in PbC/MnSe heterostructures is robust and can be observed in experiments at high temperatures. The system has great potential to have attractive applications in future spintronics.

Niels Bohr's discussions with Albert Einstein, Werner Heisenberg, and Erwin Schroedinger: the origins of the principles of uncertainty and complementarity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehra, J.

1987-05-01

In this paper, the main outlines of the discussions between Niels Bohr with Albert Einstein, Werner Heisenberg, and Erwin Schroedinger during 1920-1927 are treated. From the formulation of quantum mechanics in 1925-1926 and wave mechanics in 1926, there emerged Born's statistical interpretation of the wave function in summer 1926, and on the basis of the quantum mechanical transformation theory - formulated in fall 1926 by Dirac, London, and Jordan - Heisenberg formulated the uncertainty principle in early 1927. At the Volta Conference in Como in September 1927 and at the fifth Solvay Conference in Brussels the following month, Bohr publiclymore » enunciated his complementarity principle, which had been developing in his mind for several years. The Bohr-Einstein discussions about the consistency and completeness of quantum mechanics and of physical theory as such - formally begun in October 1927 at the fifth Solvay Conference and carried on at the sixth Solvay Conference in October 1930 - were continued during the next decades. All these aspects are briefly summarized.« less

Enhancing the Therapy Experience Using Principles of Video Game Design.

PubMed

Folkins, John Wm; Brackenbury, Tim; Krause, Miriam; Haviland, Allison

2016-02-01

This article considers the potential benefits that applying design principles from contemporary video games may have on enhancing therapy experiences. Six principles of video game design are presented, and their relevance for enriching clinical experiences is discussed. The motivational and learning benefits of each design principle have been discussed in the education literature as having positive impacts on student motivation and learning and are related here to aspects of clinical practice. The essential experience principle suggests connecting all aspects of the experience around a central emotion or cognitive connection. The discovery principle promotes indirect learning in focused environments. The risk-taking principle addresses the uncertainties clients face when attempting newly learned skills in novel situations. The generalization principle encourages multiple opportunities for skill transfer. The reward system principle directly relates to the scaffolding of frequent and varied feedback in treatment. Last, the identity principle can assist clients in using their newly learned communication skills to redefine self-perceptions. These principles highlight areas for research and interventions that may be used to reinforce or advance current practice.

Quasiparticle Energies and Band Gaps in Graphene Nanoribbons

NASA Astrophysics Data System (ADS)

Yang, Li; Park, Cheol-Hwan; Son, Young-Woo; Cohen, Marvin L.; Louie, Steven G.

2007-11-01

We present calculations of the quasiparticle energies and band gaps of graphene nanoribbons (GNRs) carried out using a first-principles many-electron Green’s function approach within the GW approximation. Because of the quasi-one-dimensional nature of a GNR, electron-electron interaction effects due to the enhanced screened Coulomb interaction and confinement geometry greatly influence the quasiparticle band gap. Compared with previous tight-binding and density functional theory studies, our calculated quasiparticle band gaps show significant self-energy corrections for both armchair and zigzag GNRs, in the range of 0.5 3.0 eV for ribbons of width 2.4 0.4 nm. The quasiparticle band gaps found here suggest that use of GNRs for electronic device components in ambient conditions may be viable.

Business Simulation Exercises in Small Business Management Education: Using Principles and Ideas from Action Learning

ERIC Educational Resources Information Center

Gabrielsson, Jonas; Tell, Joakim; Politis, Diamanto

2010-01-01

Recent calls to close the rigour-relevance gap in business school education have suggested incorporating principles and ideas from action learning in small business management education. In this paper we discuss how business simulation exercises can be used as a platform to trigger students' learning by providing them with a platform where they…

Minimizing Significant Figure Fuzziness.

ERIC Educational Resources Information Center

Fields, Lawrence D.; Hawkes, Stephen J.

1986-01-01

Addresses the principles and problems associated with the use of significant figures. Explains uncertainty, the meaning of significant figures, the Simple Rule, the Three Rule, and the 1-5 Rule. Also provides examples of the Rules. (ML)

Generalized Uncertainty Principle and Parikh-Wilczek Tunneling

NASA Astrophysics Data System (ADS)

Mehdipour, S. Hamid

We investigate the modifications of the Hawking radiation by the Generalized Uncertainty Principle (GUP) and the tunneling process. By using the GUP-corrected de Broglie wavelength, the squeezing of the fundamental momentum cell, and consequently a GUP-corrected energy, we find the nonthermal effects which lead to a nonzero statistical correlation function between probabilities of tunneling of two massive particles with different energies. Then the recovery of part of the information from the black hole radiation is feasible. From the other point of view, the inclusion of the effects of quantum gravity as the GUP expression can halt the evaporation process, so that a stable black hole remnant is left behind, including the other part of the black hole information content. Therefore, these features of the Planck-scale corrections may solve the information problem in black hole evaporation.

Modification of Schrödinger-Newton equation due to braneworld models with minimal length

NASA Astrophysics Data System (ADS)

Bhat, Anha; Dey, Sanjib; Faizal, Mir; Hou, Chenguang; Zhao, Qin

2017-07-01

We study the correction of the energy spectrum of a gravitational quantum well due to the combined effect of the braneworld model with infinite extra dimensions and generalized uncertainty principle. The correction terms arise from a natural deformation of a semiclassical theory of quantum gravity governed by the Schrödinger-Newton equation based on a minimal length framework. The two fold correction in the energy yields new values of the spectrum, which are closer to the values obtained in the GRANIT experiment. This raises the possibility that the combined theory of the semiclassical quantum gravity and the generalized uncertainty principle may provide an intermediate theory between the semiclassical and the full theory of quantum gravity. We also prepare a schematic experimental set-up which may guide to the understanding of the phenomena in the laboratory.

Quantitative Feedback Technique (QFT): Bridging the Gap

DTIC Science & Technology

2003-05-01

with Eq. (2) illustrates: (a) the effect of changes of the uncertainty set P(s) upon the output of the closed -loop control system is reduced by the...Bridging the Gap root-locus technique the dominant closed -loop poles are determined for a ζ= 0.45. Table 3 presents the required value of Kx and...degree of decoupling will have been enhanced. Method 1 is then more readily applicable, with the additional benefit of reduced closed -loop BW. E.R.2

Energy and Uncertainty in General Relativity

NASA Astrophysics Data System (ADS)

Cooperstock, F. I.; Dupre, M. J.

2018-03-01

The issue of energy and its potential localizability in general relativity has challenged physicists for more than a century. Many non-invariant measures were proposed over the years but an invariant measure was never found. We discovered the invariant localized energy measure by expanding the domain of investigation from space to spacetime. We note from relativity that the finiteness of the velocity of propagation of interactions necessarily induces indefiniteness in measurements. This is because the elements of actual physical systems being measured as well as their detectors are characterized by entire four-velocity fields, which necessarily leads to information from a measured system being processed by the detector in a spread of time. General relativity adds additional indefiniteness because of the variation in proper time between elements. The uncertainty is encapsulated in a generalized uncertainty principle, in parallel with that of Heisenberg, which incorporates the localized contribution of gravity to energy. This naturally leads to a generalized uncertainty principle for momentum as well. These generalized forms and the gravitational contribution to localized energy would be expected to be of particular importance in the regimes of ultra-strong gravitational fields. We contrast our invariant spacetime energy measure with the standard 3-space energy measure which is familiar from special relativity, appreciating why general relativity demands a measure in spacetime as opposed to 3-space. We illustrate the misconceptions by certain authors of our approach.

Measuring uncertainty by extracting fuzzy rules using rough sets and extracting fuzzy rules under uncertainty and measuring definability using rough sets

NASA Technical Reports Server (NTRS)

Worm, Jeffrey A.; Culas, Donald E.

1991-01-01

Computers are not designed to handle terms where uncertainty is present. To deal with uncertainty, techniques other than classical logic must be developed. This paper examines the concepts of statistical analysis, the Dempster-Shafer theory, rough set theory, and fuzzy set theory to solve this problem. The fundamentals of these theories are combined to provide the possible optimal solution. By incorporating principles from these theories, a decision-making process may be simulated by extracting two sets of fuzzy rules: certain rules and possible rules. From these rules a corresponding measure of how much we believe these rules is constructed. From this, the idea of how much a fuzzy diagnosis is definable in terms of its fuzzy attributes is studied.

A Bayesian Framework of Uncertainties Integration in 3D Geological Model

NASA Astrophysics Data System (ADS)

Liang, D.; Liu, X.

2017-12-01

3D geological model can describe complicated geological phenomena in an intuitive way while its application may be limited by uncertain factors. Great progress has been made over the years, lots of studies decompose the uncertainties of geological model to analyze separately, while ignored the comprehensive impacts of multi-source uncertainties. Great progress has been made over the years, while lots of studies ignored the comprehensive impacts of multi-source uncertainties when analyzed them item by item from each source. To evaluate the synthetical uncertainty, we choose probability distribution to quantify uncertainty, and propose a bayesian framework of uncertainties integration. With this framework, we integrated data errors, spatial randomness, and cognitive information into posterior distribution to evaluate synthetical uncertainty of geological model. Uncertainties propagate and cumulate in modeling process, the gradual integration of multi-source uncertainty is a kind of simulation of the uncertainty propagation. Bayesian inference accomplishes uncertainty updating in modeling process. Maximum entropy principle makes a good effect on estimating prior probability distribution, which ensures the prior probability distribution subjecting to constraints supplied by the given information with minimum prejudice. In the end, we obtained a posterior distribution to evaluate synthetical uncertainty of geological model. This posterior distribution represents the synthetical impact of all the uncertain factors on the spatial structure of geological model. The framework provides a solution to evaluate synthetical impact on geological model of multi-source uncertainties and a thought to study uncertainty propagation mechanism in geological modeling.

Learning from hackers: open-source clinical trials.

PubMed

Dunn, Adam G; Day, Richard O; Mandl, Kenneth D; Coiera, Enrico

2012-05-02

Open sharing of clinical trial data has been proposed as a way to address the gap between the production of clinical evidence and the decision-making of physicians. A similar gap was addressed in the software industry by their open-source software movement. Here, we examine how the social and technical principles of the movement can guide the growth of an open-source clinical trial community.

A Risk-Based Approach for Aerothermal/TPS Analysis and Testing

NASA Technical Reports Server (NTRS)

Wright, Michael J.; Grinstead, Jay H.; Bose, Deepak

2007-01-01

The current status of aerothermal and thermal protection system modeling for civilian entry missions is reviewed. For most such missions, the accuracy of our simulations is limited not by the tools and processes currently employed, but rather by reducible deficiencies in the underlying physical models. Improving the accuracy of and reducing the uncertainties in these models will enable a greater understanding of the system level impacts of a particular thermal protection system and of the system operation and risk over the operational life of the system. A strategic plan will be laid out by which key modeling deficiencies can be identified via mission-specific gap analysis. Once these gaps have been identified, the driving component uncertainties are determined via sensitivity analyses. A Monte-Carlo based methodology is presented for physics-based probabilistic uncertainty analysis of aerothermodynamics and thermal protection system material response modeling. These data are then used to advocate for and plan focused testing aimed at reducing key uncertainties. The results of these tests are used to validate or modify existing physical models. Concurrently, a testing methodology is outlined for thermal protection materials. The proposed approach is based on using the results of uncertainty/sensitivity analyses discussed above to tailor ground testing so as to best identify and quantify system performance and risk drivers. A key component of this testing is understanding the relationship between the test and flight environments. No existing ground test facility can simultaneously replicate all aspects of the flight environment, and therefore good models for traceability to flight are critical to ensure a low risk, high reliability thermal protection system design. Finally, the role of flight testing in the overall thermal protection system development strategy is discussed.

The Electronic Properties of O-Doped Pure and Sulfur Vacancy-Defect Monolayer WS₂: A First-Principles Study.

PubMed

Wang, Weidong; Bai, Liwen; Yang, Chenguang; Fan, Kangqi; Xie, Yong; Li, Minglin

2018-01-31

Based on the density functional theory (DFT), the electronic properties of O-doped pure and sulfur vacancy-defect monolayer WS₂ are investigated by using the first-principles method. For the O-doped pure monolayer WS₂, four sizes (2 × 2 × 1, 3 × 3 × 1, 4 × 4 × 1 and 5 × 5 × 1) of supercell are discussed to probe the effects of O doping concentration on the electronic structure. For the 2 × 2 × 1 supercell with 12.5% O doping concentration, the band gap of O-doped pure WS₂ is reduced by 8.9% displaying an indirect band gap. The band gaps in 3 × 3 × 1 and 4 × 4 × 1 supercells are both opened to some extent, respectively, for 5.55% and 3.13% O doping concentrations, while the band gap in 5 × 5 × 1 supercell with 2.0% O doping concentration is quite close to that of the pure monolayer WS₂. Then, two typical point defects, including sulfur single-vacancy (V S ) and sulfur divacancy (V 2S ), are introduced to probe the influences of O doping on the electronic properties of WS₂ monolayers. The observations from DFT calculations show that O doping can broaden the band gap of monolayer WS₂ with V S defect to a certain degree, but weaken the band gap of monolayer WS₂ with V 2S defect. Doping O element into either pure or sulfur vacancy-defect monolayer WS₂ cannot change their band gaps significantly, however, it still can be regarded as a potential method to slightly tune the electronic properties of monolayer WS₂.

Estimating structural collapse fragility of generic building typologies using expert judgment

USGS Publications Warehouse

Jaiswal, Kishor; Wald, David J.; Perkins, David M.; Aspinall, Willy P.; Kiremidjian, Anne S.

2014-01-01

The structured expert elicitation process proposed by Cooke (1991), hereafter referred to as Cooke's approach, is applied for the first time in the realm of structural collapse-fragility assessment for selected generic construction types. Cooke's approach works on the principle of objective calibration scoring of judgments couple with hypothesis testing used in classical statistics. The performance-based scoring system reflects the combined measure of an expert's informativeness about variables in the problem are under consideration, and their ability to enumerate, in a statistically accurate way through expressing their true beliefs, the quantitative uncertainties associated with their assessments. We summarize the findings of an expert elicitation workshop in which a dozen earthquake-engineering professionals from around the world were engaged to estimate seismic collapse fragility for generic construction types. Development of seismic collapse fragility-functions was accomplished by combining their judgments using weights derived from Cooke's method. Although substantial effort was needed to elicit the inputs of these experts successfully, we anticipate that the elicitation strategy described here will gain momentum in a wide variety of earthquake seismology and engineering hazard and risk analyses where physical model and data limitations are inherent and objective professional judgment can fill gaps.

Estimating structural collapse fragility of generic building typologies using expert judgment

USGS Publications Warehouse

Jaiswal, Kishor S.; Wald, D.J.; Perkins, D.; Aspinall, W.P.; Kiremidjian, Anne S.; Deodatis, George; Ellingwood, Bruce R.; Frangopol, Dan M.

2014-01-01

The structured expert elicitation process proposed by Cooke (1991), hereafter referred to as Cooke’s approach, is applied for the first time in the realm of structural collapse-fragility assessment for selected generic construction types. Cooke’s approach works on the principle of objective calibration scoring of judgments coupled with hypothesis testing used in classical statistics. The performance-based scoring system reflects the combined measure of an expert’s informativeness about variables in the problem area under consideration, and their ability to enumerate, in a statistically accurate way through expressing their true beliefs, the quantitative uncertainties associated with their assessments. We summarize the findings of an expert elicitation workshop in which a dozen earthquake-engineering professionals from around the world were engaged to estimate seismic collapse fragility for generic construction types. Development of seismic collapse fragility functions was accomplished by combining their judgments using weights derived from Cooke’s method. Although substantial effort was needed to elicit the inputs of these experts successfully, we anticipate that the elicitation strategy described here will gain momentum in a wide variety of earthquake seismology and engineering hazard and risk analyses where physical model and data limitations are inherent and objective professional judgment can fill gaps.

Cyanobacterial toxins: risk management for health protection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Codd, Geoffrey A.; Morrison, Louise F.; Metcalf, James S

2005-03-15

This paper reviews the occurrence and properties of cyanobacterial toxins, with reference to the recognition and management of the human health risks which they may present. Mass populations of toxin-producing cyanobacteria in natural and controlled waterbodies include blooms and scums of planktonic species, and mats and biofilms of benthic species. Toxic cyanobacterial populations have been reported in freshwaters in over 45 countries, and in numerous brackish, coastal, and marine environments. The principal toxigenic genera are listed. Known sources of the families of cyanobacterial toxins (hepato-, neuro-, and cytotoxins, irritants, and gastrointestinal toxins) are briefly discussed. Key procedures in the riskmore » management of cyanobacterial toxins and cells are reviewed, including derivations (where sufficient data are available) of tolerable daily intakes (TDIs) and guideline values (GVs) with reference to the toxins in drinking water, and guideline levels for toxigenic cyanobacteria in bathing waters. Uncertainties and some gaps in knowledge are also discussed, including the importance of exposure media (animal and plant foods), in addition to potable and recreational waters. Finally, we present an outline of steps to develop and implement risk management strategies for cyanobacterial cells and toxins in waterbodies, with recent applications and the integration of Hazard Assessment Critical Control Point (HACCP) principles.« less

Chaos in the Classroom.

ERIC Educational Resources Information Center

Jackett, Dwane

1990-01-01

Described is a science activity which illustrates the principle of uncertainty using a computer simulation of bacterial reproduction. Procedures and results are discussed. Several illustrations of results are provided. The availability of a computer program is noted. (CW)

Organizing principles as tools for bridging the gap between system theory and biological experimentation.

PubMed

Mekios, Constantinos

2016-04-01

Twentieth-century theoretical efforts towards the articulation of general system properties came short of having the significant impact on biological practice that their proponents envisioned. Although the latter did arrive at preliminary mathematical formulations of such properties, they had little success in showing how these could be productively incorporated into the research agenda of biologists. Consequently, the gap that kept system-theoretic principles cut-off from biological experimentation persisted. More recently, however, simple theoretical tools have proved readily applicable within the context of systems biology. In particular, examples reviewed in this paper suggest that rigorous mathematical expressions of design principles, imported primarily from engineering, could produce experimentally confirmable predictions of the regulatory properties of small biological networks. But this is not enough for contemporary systems biologists who adopt the holistic aspirations of early systemologists, seeking high-level organizing principles that could provide insights into problems of biological complexity at the whole-system level. While the presented evidence is not conclusive about whether this strategy could lead to the realization of the lofty goal of a comprehensive explanatory integration, it suggests that the ongoing quest for organizing principles is pragmatically advantageous for systems biologists. The formalisms postulated in the course of this process can serve as bridges between system-theoretic concepts and the results of molecular experimentation: they constitute theoretical tools for generalizing molecular data, thus producing increasingly accurate explanations of system-wide phenomena.

Building Quantitative Hydrologic Storylines from Process-based Models for Managing Water Resources in the U.S. Under Climate-changed Futures

NASA Astrophysics Data System (ADS)

Arnold, J.; Gutmann, E. D.; Clark, M. P.; Nijssen, B.; Vano, J. A.; Addor, N.; Wood, A.; Newman, A. J.; Mizukami, N.; Brekke, L. D.; Rasmussen, R.; Mendoza, P. A.

2016-12-01

Climate change narratives for water-resource applications must represent the change signals contextualized by hydroclimatic process variability and uncertainty at multiple scales. Building narratives of plausible change includes assessing uncertainties across GCM structure, internal climate variability, climate downscaling methods, and hydrologic models. Work with this linked modeling chain has dealt mostly with GCM sampling directed separately to either model fidelity (does the model correctly reproduce the physical processes in the world?) or sensitivity (of different model responses to CO2 forcings) or diversity (of model type, structure, and complexity). This leaves unaddressed any interactions among those measures and with other components in the modeling chain used to identify water-resource vulnerabilities to specific climate threats. However, time-sensitive, real-world vulnerability studies typically cannot accommodate a full uncertainty ensemble across the whole modeling chain, so a gap has opened between current scientific knowledge and most routine applications for climate-changed hydrology. To close that gap, the US Army Corps of Engineers, the Bureau of Reclamation, and the National Center for Atmospheric Research are working on techniques to subsample uncertainties objectively across modeling chain components and to integrate results into quantitative hydrologic storylines of climate-changed futures. Importantly, these quantitative storylines are not drawn from a small sample of models or components. Rather, they stem from the more comprehensive characterization of the full uncertainty space for each component. Equally important from the perspective of water-resource practitioners, these quantitative hydrologic storylines are anchored in actual design and operations decisions potentially affected by climate change. This talk will describe part of our work characterizing variability and uncertainty across modeling chain components and their interactions using newly developed observational data, models and model outputs, and post-processing tools for making the resulting quantitative storylines most useful in practical hydrology applications.

Uncertainties in historical pollution data from sedimentary records from an Australian urban floodplain lake

NASA Astrophysics Data System (ADS)

Lintern, A.; Leahy, P.; Deletic, A.; Heijnis, H.; Zawadzki, A.; Gadd, P.; McCarthy, D.

2018-05-01

Sediment cores from aquatic environments can provide valuable information about historical pollution levels and sources. However, there is little understanding of the uncertainties associated with these findings. The aim of this study is to fill this knowledge gap by proposing a framework for quantifying the uncertainties in historical heavy metal pollution records reconstructed from sediment cores. This uncertainty framework consists of six sources of uncertainty: uncertainties in (1) metals analysis methods, (2) spatial variability of sediment core heavy metal profiles, (3) sub-sampling intervals, (4) the sediment chronology, (5) the assumption that metal levels in bed sediments reflect the magnitude of metal inputs into the aquatic system, and (6) post-depositional transformation of metals. We apply this uncertainty framework to an urban floodplain lake in South-East Australia (Willsmere Billabong). We find that for this site, uncertainties in historical dated heavy metal profiles can be up to 176%, largely due to uncertainties in the sediment chronology, and in the assumption that the settled heavy metal mass is equivalent to the heavy metal mass entering the aquatic system. As such, we recommend that future studies reconstructing historical pollution records using sediment cores from aquatic systems undertake an investigation of the uncertainties in the reconstructed pollution record, using the uncertainty framework provided in this study. We envisage that quantifying and understanding the uncertainties associated with the reconstructed pollution records will facilitate the practical application of sediment core heavy metal profiles in environmental management projects.

Linear, multivariable robust control with a mu perspective

NASA Technical Reports Server (NTRS)

Packard, Andy; Doyle, John; Balas, Gary

1993-01-01

The structured singular value is a linear algebra tool developed to study a particular class of matrix perturbation problems arising in robust feedback control of multivariable systems. These perturbations are called linear fractional, and are a natural way to model many types of uncertainty in linear systems, including state-space parameter uncertainty, multiplicative and additive unmodeled dynamics uncertainty, and coprime factor and gap metric uncertainty. The structured singular value theory provides a natural extension of classical SISO robustness measures and concepts to MIMO systems. The structured singular value analysis, coupled with approximate synthesis methods, make it possible to study the tradeoff between performance and uncertainty that occurs in all feedback systems. In MIMO systems, the complexity of the spatial interactions in the loop gains make it difficult to heuristically quantify the tradeoffs that must occur. This paper examines the role played by the structured singular value (and its computable bounds) in answering these questions, as well as its role in the general robust, multivariable control analysis and design problem.

Electronic structure and its external electric field modulation of PbPdO2 ultrathin slabs with (002) and (211) preferred orientations.

PubMed

Yang, Yanmin; Zhong, Kehua; Xu, Guigui; Zhang, Jian-Min; Huang, Zhigao

2017-07-31

The Electronic structure of PbPdO 2 with (002) and (211) preferred orientations were investigated using first-principles calculation. The calculated results indicate that, (002) and (211) orientations exhibit different electric field dependence of band-gap and carrier concentration. The small band gap and more sensitive electric field modulation of band gap were found in (002) orientation. Moreover, the electric field modulation of the resistivity up to 3-4 orders of magnitude is also observed in (002) slab, which reveals that origin of colossal electroresistance. Lastly, electric field modulation of band gap is well explained. This work should be significant for repeating the colossal electroresistance.

The Zika Virus Outbreak in Brazil: Knowledge Gaps and Challenges for Risk Reduction.

PubMed

Garcia Serpa Osorio-de-Castro, Claudia; Silva Miranda, Elaine; Machado de Freitas, Carlos; Rochel de Camargo, Kenneth; Cranmer, Hilarie Hartel

2017-06-01

We analyzed uncertainties and complexities of the Zika virus outbreak in Brazil, and we discuss risk reduction for future emergencies. We present the public health situation in Brazil and concurrent determinants of the epidemic and the knowledge gaps that persist despite building evidence from research, making public health decisions difficult. Brazil has adopted active measures, but producing desired outcomes may be uncertain because of partial or unavailable information. Reducing population group vulnerabilities and acting on environmental issues are medium- to long-term measures. Simultaneously dealing with information gaps, uncontrolled disease spread, and vulnerabilities is a new risk scenario and must be approached decisively to face emerging biothreats.

Traceable measurements of the electrical parameters of solid-state lighting products

NASA Astrophysics Data System (ADS)

Zhao, D.; Rietveld, G.; Braun, J.-P.; Overney, F.; Lippert, T.; Christensen, A.

2016-12-01

In order to perform traceable measurements of the electrical parameters of solid-state lighting (SSL) products, it is necessary to technically adequately define the measurement procedures and to identify the relevant uncertainty sources. The present published written standard for SSL products specifies test conditions, but it lacks an explanation of how adequate these test conditions are. More specifically, both an identification of uncertainty sources and a quantitative uncertainty analysis are absent. This paper fills the related gap in the present written standard. New uncertainty sources with respect to conventional lighting sources are determined and their effects are quantified. It shows that for power measurements, the main uncertainty sources are temperature deviation, power supply voltage distortion, and instability of the SSL product. For current RMS measurements, the influence of bandwidth, shunt resistor, power supply source impedance and ac frequency flatness are significant as well. The measurement uncertainty depends not only on the test equipment but is also a function of the characteristics of the device under test (DUT), for example, current harmonics spectrum and input impedance. Therefore, an online calculation tool is provided to help non-electrical experts. Following our procedures, unrealistic uncertainty estimations, unnecessary procedures and expensive equipment can be prevented.

Applying principles from the game theory to acute stroke care: Learning from the prisoner's dilemma, stag-hunt, and other strategies.

PubMed

Saposnik, Gustavo; Johnston, S Claiborne

2016-04-01

Acute stroke care represents a challenge for decision makers. Decisions based on erroneous assessments may generate false expectations of patients and their family members, and potentially inappropriate medical advice. Game theory is the analysis of interactions between individuals to study how conflict and cooperation affect our decisions. We reviewed principles of game theory that could be applied to medical decisions under uncertainty. Medical decisions in acute stroke care are usually made under constrains: short period of time, with imperfect clinical information, limit understanding about patients and families' values and beliefs. Game theory brings some strategies to help us manage complex medical situations under uncertainty. For example, it offers a different perspective by encouraging the consideration of different alternatives through the understanding of patients' preferences and the careful evaluation of cognitive distortions when applying 'real-world' data. The stag-hunt game teaches us the importance of trust to strength cooperation for a successful patient-physician interaction that is beyond a good or poor clinical outcome. The application of game theory to stroke care may improve our understanding of complex medical situations and help clinicians make practical decisions under uncertainty. © 2016 World Stroke Organization.

Mechanics of Fluid-Filled Interstitial Gaps. I. Modeling Gaps in a Compact Tissue.

PubMed

Parent, Serge E; Barua, Debanjan; Winklbauer, Rudolf

2017-08-22

Fluid-filled interstitial gaps are a common feature of compact tissues held together by cell-cell adhesion. Although such gaps can in principle be the result of weak, incomplete cell attachment, adhesion is usually too strong for this to occur. Using a mechanical model of tissue cohesion, we show that, instead, a combination of local prevention of cell adhesion at three-cell junctions by fluidlike extracellular material and a reduction of cortical tension at the gap surface are sufficient to generate stable gaps. The size and shape of these interstitial gaps depends on the mechanical tensions between cells and at gap surfaces, and on the difference between intracellular and interstitial pressures that is related to the volume of the interstitial fluid. As a consequence of the dependence on tension/tension ratios, the presence of gaps does not depend on the absolute strength of cell adhesion, and similar gaps are predicted to occur in tissues of widely differing cohesion. Tissue mechanical parameters can also vary within and between cells of a given tissue, generating asymmetrical gaps. Within limits, these can be approximated by symmetrical gaps. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

The fragmentation instability of a black hole with f( R) global monopole under GUP

NASA Astrophysics Data System (ADS)

Chen, Lingshen; Cheng, Hongbo

2018-03-01

Having studied the fragmentation of the black holes containing f( R) global monopole under the generalized uncertainty principle (GUP), we show the influences from this kind of monopole, f( R) theory, and GUP on the evolution of black holes. We focus on the possibility that the black hole breaks into two parts by means of the second law of thermodynamics. We derive the entropies of the initial black hole and the broken parts while the generalization of Heisenberg's uncertainty principle is introduced. We find that the f( R) global monopole black hole keeps stable instead of splitting without the generalization because the entropy difference is negative. The fragmentation of the black hole will happen if the black hole entropies are limited by the GUP and the considerable deviation from the general relativity leads to the case that the mass of one fragmented black hole is smaller and the other one's mass is larger.

Water, Resilience and the Law: From General Concepts and Governance Design Principles to Actionable Mechanisms

NASA Astrophysics Data System (ADS)

Hill Clarvis, M.; Allan, A.; Hannah, D. M.

2013-12-01

Climate change has significant ramifications for water law and governance, yet, there is strong evidence that legal regulations have often failed to protect environments or promote sustainable development. Scholars have increasingly suggested that the preservation and restoration paradigms of legislation and regulation are no longer adequate for climate change related challenges in complex and cross-scale social-ecological systems. This is namely due to past assumptions of stationarity, uniformitarianism and the perception of ecosystem change as predictable and reversible. This paper reviews the literature on law and resilience and then presents and discusses a set of practical examples of legal mechanisms from the water resources management sector, identified according to a set of guiding principles from the literature on adaptive capacity, adaptive governance as well as adaptive and integrated water resources management. It then assesses the aptness of these different measures according to scientific evidence of increased uncertainty and changing ecological baselines. A review of the best practice examples demonstrates that there are a number of best practice examples attempting to integrate adaptive elements of flexibility, iterativity, connectivity and subsidiarity into a variety of legislative mechanisms, suggesting that there is not as significant a tension between resilience and the law as many scholars have suggested. However, while many of the mechanisms may indeed be suitable for addressing challenges relating to current levels of change and uncertainty, analysis across a broader range of uncertainty highlights challenges relating to more irreversible changes associated with greater levels of warming. Furthermore the paper identifies a set of pre-requisites that are fundamental to the successful implementation of such mechanisms, namely monitoring and data sharing, financial and technical capacity, particularly in nations that are most at risk with the least data infrastructure. The article aims to contribute to both theory and practice, enabling policy makers to translate resilience based terminology and adaptive governance principles into clear instructions for incorporating uncertainty into legislation and policy design.

Unifying decoherence and the Heisenberg Principle

NASA Astrophysics Data System (ADS)

Janssens, Bas

2017-08-01

We exhibit three inequalities involving quantum measurement, all of which are sharp and state independent. The first inequality bounds the performance of joint measurement. The second quantifies the trade-off between the measurement quality and the disturbance caused on the measured system. Finally, the third inequality provides a sharp lower bound on the amount of decoherence in terms of the measurement quality. This gives a unified description of both the Heisenberg uncertainty principle and the collapse of the wave function.

Thermodynamics and evolution.

PubMed

Demetrius, L

2000-09-07

The science of thermodynamics is concerned with understanding the properties of inanimate matter in so far as they are determined by changes in temperature. The Second Law asserts that in irreversible processes there is a uni-directional increase in thermodynamic entropy, a measure of the degree of uncertainty in the thermal energy state of a randomly chosen particle in the aggregate. The science of evolution is concerned with understanding the properties of populations of living matter in so far as they are regulated by changes in generation time. Directionality theory, a mathematical model of the evolutionary process, establishes that in populations subject to bounded growth constraints, there is a uni-directional increase in evolutionary entropy, a measure of the degree of uncertainty in the age of the immediate ancestor of a randomly chosen newborn. This article reviews the mathematical basis of directionality theory and analyses the relation between directionality theory and statistical thermodynamics. We exploit an analytic relation between temperature, and generation time, to show that the directionality principle for evolutionary entropy is a non-equilibrium extension of the principle of a uni-directional increase of thermodynamic entropy. The analytic relation between these directionality principles is consistent with the hypothesis of the equivalence of fundamental laws as one moves up the hierarchy, from a molecular ensemble where the thermodynamic laws apply, to a population of replicating entities (molecules, cells, higher organisms), where evolutionary principles prevail. Copyright 2000 Academic Press.

The research-practice gap: bridging the schism between eating disorder researchers and practitioners.

PubMed

Lilienfeld, Scott O; Ritschel, Lorie A; Lynn, Steven Jay; Brown, Amanda P; Cautin, Robin L; Latzman, Robert D

2013-07-01

The field of eating disorders (EDs) treatment has been beset by a marked disjunction between scientific evidence and clinical application. We describe the nature and scope of the research-practice gap in the ED field. We draw on surveys and broader literature to better understand the research-practice gap in ED treatment and reasons for resistance to evidence-based practice. We identify three sources of the research-practice gap: (1) attitudinal factors, (2) differences in the definition of "evidence," and (3) cognitive factors, especially naïve realism and confirmation bias. We affirm the role of science as a safeguard against human fallibility and as a means of bridging the research-practice gap, and delineate key principles of scientific thinking for ED researchers and practitioners. We conclude with proposals for narrowing the research-practice gap in ED treatment and enhancing the quality of interventions for ED clients. Copyright © 2013 Wiley Periodicals, Inc.

Band gap scaling laws in group IV nanotubes.

PubMed

Wang, Chongze; Fu, Xiaonan; Guo, Yangyang; Guo, Zhengxiao; Xia, Congxin; Jia, Yu

2017-03-17

By using the first-principles calculations, the band gap properties of nanotubes formed by group IV elements have been investigated systemically. Our results reveal that for armchair nanotubes, the energy gaps at K points in the Brillouin zone decrease as 1/r scaling law with the radii (r) increasing, while they are scaled by -1/r 2  + C at Γ points, here, C is a constant. Further studies show that such scaling law of K points is independent of both the chiral vector and the type of elements. Therefore, the band gaps of nanotubes for a given radius can be determined by these scaling laws easily. Interestingly, we also predict the existence of indirect band gap for both germanium and tin nanotubes. Our new findings provide an efficient way to determine the band gaps of group IV element nanotubes by knowing the radii, as well as to facilitate the design of functional nanodevices.

Addendum to ‘Understanding risks in the light of uncertainty: low-probability, high-impact coastal events in cities’

NASA Astrophysics Data System (ADS)

Galarraga, Ibon; Sainz de Murieta, Elisa; Markandya, Anil; María Abadie, Luis

2018-02-01

This addendum adds to the analysis presented in ‘Understanding risks in the light of uncertainty: low-probability, high-impact coastal events in cities’ Abadie et al (2017 Environ. Res. Lett. 12 014017). We propose to use the framework developed earlier to enhance communication and understanding of risks, with the aim of bridging the gap between highly technical risk management discussion to the public risk aversion debate. We also propose that the framework could be used for stress-testing resilience.

Uncertainty analysis in vulnerability estimations for elements at risk- a review of concepts and some examples on landslides

NASA Astrophysics Data System (ADS)

Ciurean, R. L.; Glade, T.

2012-04-01

Decision under uncertainty is a constant of everyday life and an important component of risk management and governance. Recently, experts have emphasized the importance of quantifying uncertainty in all phases of landslide risk analysis. Due to its multi-dimensional and dynamic nature, (physical) vulnerability is inherently complex and the "degree of loss" estimates imprecise and to some extent even subjective. Uncertainty analysis introduces quantitative modeling approaches that allow for a more explicitly objective output, improving the risk management process as well as enhancing communication between various stakeholders for better risk governance. This study presents a review of concepts for uncertainty analysis in vulnerability of elements at risk to landslides. Different semi-quantitative and quantitative methods are compared based on their feasibility in real-world situations, hazard dependency, process stage in vulnerability assessment (i.e. input data, model, output), and applicability within an integrated landslide hazard and risk framework. The resulted observations will help to identify current gaps and future needs in vulnerability assessment, including estimation of uncertainty propagation, transferability of the methods, development of visualization tools, but also address basic questions like what is uncertainty and how uncertainty can be quantified or treated in a reliable and reproducible way.

Applying the conservativeness principle to REDD to deal with the uncertainties of the estimates

NASA Astrophysics Data System (ADS)

Grassi, Giacomo; Monni, Suvi; Federici, Sandro; Achard, Frederic; Mollicone, Danilo

2008-07-01

A common paradigm when the reduction of emissions from deforestations is estimated for the purpose of promoting it as a mitigation option in the context of the United Nations Framework Convention on Climate Change (UNFCCC) is that high uncertainties in input data—i.e., area change and C stock change/area—may seriously undermine the credibility of the estimates and therefore of reduced deforestation as a mitigation option. In this paper, we show how a series of concepts and methodological tools—already existing in UNFCCC decisions and IPCC guidance documents—may greatly help to deal with the uncertainties of the estimates of reduced emissions from deforestation.

Nanomedicine photoluminescence crystal-inspired brain sensing approach

NASA Astrophysics Data System (ADS)

Fang, Yan; Wang, Fangzhen; Wu, Rong

2018-02-01

Precision sensing needs to overcome a gap of a single atomic step height standard. In response to the cutting-edge challenge, a heterosingle molecular nanomedicine crystal was developed wherein a nanomedicine crystal height less than 1 nm was designed and selfassembled on a substrate of either a highly ordered and freshly separated graphite or a N-doped silicon with hydrogen bonding by a home-made hybrid system of interacting single bioelectron donor-acceptor and a single biophoton donor-acceptor according to orthogonal mathematical optimization scheme, and an atomic spatial resolution conducting atomic force microscopy (C-AFM) with MHz signal processing by a special transformation of an atomic force microscopy (AFM) and a scanning tunneling microscopy (STM) were employed, wherein a z axis direction UV-VIS laser interferometer and a feedback circuit were used to achieve the minimized uncertainty of a micro-regional structure height and its corresponding local differential conductance quantization (spin state) process was repeatedly measured with a highly time resolution, as well as a pulsed UV-VIS laser micro-photoluminescence (PL) spectrum with a single photon resolution was set up by traceable quantum sensing and metrology relied up a quantum electrical triangle principle. The coupling of a single bioelectron conducting, a single biophoton photoluminescence, a frequency domain temporal spin phase in nanomedicine crystal-inspired sensing methods and sensor technologies were revealed by a combination of C-AFM and PL measurement data-based mathematic analyses1-3, as depicted in Figure 1 and repeated in nanomedicine crystals with a single atomic height. It is concluded that height-current-phase uncertainty correlation pave a way to develop a brain imaging and a single atomic height standard, quantum sensing, national security, worldwide impact1-3 technology and beyond.

Pressure-Induced Structural Transition and Enhancement of Energy Gap of CuAlO2

NASA Astrophysics Data System (ADS)

Nakanishi, Akitaka

2011-02-01

By using first-principles calculations, we studied the stable crystal structures and energy gaps of CuAlO2 under high pressure. Our simulation shows that CuAlO2 transforms from a delafossite structure to a leaning delafossite structure. The critical pressure of the transition was determined to be 60 GPa. The energy gap of CuAlO2 increases through the structural transition due to the enhanced covalency of Cu 3d and O 2p states. We found that a chalcopyrite structure does not appear as a stable structure under high pressure.

Band gaps and the possible effect on impact sensitivity for some nitro aromatic explosive materials

NASA Astrophysics Data System (ADS)

Zhang, Hong; Cheung, Frankie; Zhao, Feng; Cheng, Xin-Lu

The first principle density functional theory method SIESTA has been used to compute the band gap of several polynitroaromatic explosives, such as TATB, DATB, TNT, and picric acid. In these systems, the weakest bond is the one between an NO2 group and the aromatic ring. The bond dissociation energy (BDE) alone cannot predicate the relative sensitivity to impact of these four systems correctly. It was found that their relative impact sensitivity could be explained by considering the BDE and the band gap value of the crystal state together.

Band-gap bowing and p-type doping of (Zn, Mg, Be)O wide-gap semiconductor alloys: a first-principles study

NASA Astrophysics Data System (ADS)

Shi, H.-L.; Duan, Y.

2008-12-01

Using a first-principles band-structure method and a special quasirandom structure (SQS) approach, we systematically calculate the band gap bowing parameters and p-type doping properties of (Zn, Mg, Be)O related random ternary and quaternary alloys. We show that the bowing parameters for ZnBeO and MgBeO alloys are large and dependent on composition. This is due to the size difference and chemical mismatch between Be and Zn(Mg) atoms. We also demonstrate that adding a small amount of Be into MgO reduces the band gap indicating that the bowing parameter is larger than the band-gap difference. We select an ideal N atom with lower p atomic energy level as dopant to perform p-type doping of ZnBeO and ZnMgBeO alloys. For N doped in ZnBeO alloy, we show that the acceptor transition energies become shallower as the number of the nearest neighbor Be atoms increases. This is thought to be because of the reduction of p- d repulsion. The NO acceptor transition energies are deep in the ZnMgBeO quaternary alloy lattice-matched to GaN substrate due to the lower valence band maximum. These decrease slightly as there are more nearest neighbor Mg atoms surrounding the N dopant. The important natural valence band alignment between ZnO, MgO, BeO, ZnBeO, and ZnMgBeO quaternary alloy is also investigated.

Alcohol molecules adsorption on graphane nanosheets - A first-principles investigation

NASA Astrophysics Data System (ADS)

Nagarajan, V.; Chandiramouli, R.

2018-05-01

The geometric structure, electronic and adsorption properties of methanol, ethanol and 1-propanol molecules on hydrogenated graphene (graphane) were investigated using first-principles calculations. The stability of graphane base material is confirmed using formation energy and phonon band structures. The adsorption of alcohol molecules on bare graphane and hydrogen vacant graphane nanosheet is found to be prominent and the selectivity of alcohol molecules can be achieved using bare or hydrogen vacant graphane nanosheet. Moreover, the interaction of alcohol molecules on bare and hydrogen vacant graphane nanosheets is studied using the adsorption energy, energy band gap variation, Bader charge transfer and average energy band gap variation. The adsorption energy ranges from -0.149 to -0.383 eV upon alcohol adsorption. The energy gap varies from 4.71 to 2.62 eV for bare graphane and from 4.02 to 3.60 eV for hydrogen vacant graphane nanosheets upon adsorption of alcohol molecules. The adsorption properties of alcohol molecules provide useful information for the possible application of graphane nanosheet as a base material for the detection of alcohol molecules.

First Principles Studies for Lithium Intercalation and Diffusion Behaviors in MoS2 treated with the Compressive Sensing Cluster Expansion

NASA Astrophysics Data System (ADS)

Liu, Chi-Ping; Zhou, Fei; Ozolins, Vidvuds

2014-03-01

Molybdenum disulfide (MoS2) is a good candidate electrode material for high capacity energy storage applications, such as lithium ion batteries and supercapacitors. In this work, we investigate lithium intercalation and diffusion kinetics in MoS2 by using first-principles density-functional theory (DFT) calculations. Two different lithium intercalation sites (1-H and 2-T) in MoS2 are found to be stable for lithium intercalation at different van der Waals' (vdW) gap distances. It is found that both thermodynamic and kinetic properties are highly related to the interlayer vdW gap distance, and that the optimal gap distance leads to effective solid-state diffusion in MoS2. Additionally, through the use of compressive sensing, we build accurate cluster expansion models to study the thermodynamic properties of MoS2 at high lithium content by truncating the higher order effective clusters with significant contributions. The results show that compressive sensing cluster expansion is a rigorous and powerful tool for model construction for advanced electrochemical applications in the future.

Inhibition of quantum size effects from surface dangling bonds: The first principles study on different morphology SiC nanowires

NASA Astrophysics Data System (ADS)

Li, Yan-Jing; Li, Shu-Long; Gong, Pei; Li, Ya-Lin; Fang, Xiao-Yong; Jia, Ya-Hui; Cao, Mao-Sheng

2018-06-01

In recent years, we investigated the structure and photoelectric properties of Silicon carbide nanowires (SiCNWs) with different morphologies and sizes by using the first-principle in density functional theory, and found a phenomenon that is opposite to quantum size effect, namely, the band gap of nanowires increases with the increase of the diameter. To reveal the nature of this phenomenon, we further carry out the passivation of SiCNWs. The results show that the hydrogenated SiCNWs are direct band gap semiconductors, and the band gap decreases with the diameter increasing, which indicates the dangling bonds of the SiCNWs suppress its quantum size effect. The optical properties of SiCNWs with different diameters before and after hydrogenated are compared, we found that these surface dangling bonds lead to spectral shift which is different with quantum size effect of SiCNWs. These results have potential scientific value to deepen the understanding of the photoelectric properties of SiCNWs and to promote the development of optoelectronic devices.

Translating Policy Principles into Practice to Improve Health Care Access for Adults with Intellectual Disabilities: A Research Review of the Past Decade

ERIC Educational Resources Information Center

Krahn, Glora L.; Drum, Charles, E.

2007-01-01

This article extracts principles from two Surgeon General reports, "Closing the Gap: A National Blueprint to Improve the Health of Persons with Mental Retardation" (2002) and "Call to Action to Improve the Health and Wellness of Persons with Disabilities" (2005), and combines them with the Objectives from "Chapter 6 of Healthy People 2010" to…

Keeping Up With the Drones: Is Just War Theory Obsolete

DTIC Science & Technology

2010-04-29

the laws of armed conflict. For centuries, just war principles have defined how responsible states have agreed to ethically wage war. The manner in...conflict. For centuries, just war principles have defined how responsible states have agreed to ethically wage war. The manner in which unmanned...3 will be morally and ethically waged. Failure to address the gaps this new technology exposes in traditional teachings will have profound

Estimation of Spatial Trends in LAI in Heterogeneous Semi-arid Ecosystems using Full Waveform Lidar

NASA Astrophysics Data System (ADS)

Glenn, N. F.; Ilangakoon, N.; Spaete, L.; Dashti, H.

2017-12-01

Leaf area index (LAI) is a key structural trait that is defined by the plant functional type (PFT) and controlled by prevailing climate- and human-driven ecosystem stresses. Estimates of LAI using remote sensing techniques are limited by the uncertainties of vegetation inter and intra-gap fraction estimates; this is especially the case in sparse, low stature vegetated ecosystems. Small footprint full waveform lidar digitizes the total amount of return energy with the direction information as a near continuous waveform at a high vertical resolution (1 ns). Thus waveform lidar provides additional data matrices to capture vegetation gaps as well as PFTs that can be used to constrain the uncertainties of LAI estimates. In this study, we calculated a radiometrically calibrated full waveform parameter called backscatter cross section, along with other data matrices from the waveform to estimate vegetation gaps across plots (10 m x 10 m) in a semi-arid ecosystem in the western US. The LAI was then estimated using empirical relationships with directional gap fraction. Full waveform-derived gap fraction based LAI showed a high correlation with field observed shrub LAI (R2 = 0.66, RMSE = 0.24) compared to discrete return lidar based LAI (R2 = 0.01, RMSE = 0.5). The data matrices derived from full waveform lidar classified a number of deciduous and evergreen tree species, shrub species, and bare ground with an overall accuracy of 89% at 10 m. A similar analysis was performed at 1m with overall accuracy of 80%. The next step is to use these relationships to map the PFTs LAI at 10 m spatial scale across the larger study regions. The results show the exciting potential of full waveform lidar to identify plant functional types and LAI in low-stature vegetation dominated semi-arid ecosystems, an ecosystem in which many other remote sensing techniques fail. These results can be used to assess ecosystem state, habitat suitability as well as to constrain model uncertainties in vegetation dynamic models with a combination of other remote sensing techniques. Multi-spatial resolution (1 m and 10 m) studies provide basic information on the applicability and detection thresholds of future global satellite sensors designed at coarser spatial resolutions (e.g. GEDI, ICESat-2) in semi-arid ecosystems.

Improving the driver-automation interaction: an approach using automation uncertainty.

PubMed

Beller, Johannes; Heesen, Matthias; Vollrath, Mark

2013-12-01

The aim of this study was to evaluate whether communicating automation uncertainty improves the driver-automation interaction. A false system understanding of infallibility may provoke automation misuse and can lead to severe consequences in case of automation failure. The presentation of automation uncertainty may prevent this false system understanding and, as was shown by previous studies, may have numerous benefits. Few studies, however, have clearly shown the potential of communicating uncertainty information in driving. The current study fills this gap. We conducted a driving simulator experiment, varying the presented uncertainty information between participants (no uncertainty information vs. uncertainty information) and the automation reliability (high vs.low) within participants. Participants interacted with a highly automated driving system while engaging in secondary tasks and were required to cooperate with the automation to drive safely. Quantile regressions and multilevel modeling showed that the presentation of uncertainty information increases the time to collision in the case of automation failure. Furthermore, the data indicated improved situation awareness and better knowledge of fallibility for the experimental group. Consequently, the automation with the uncertainty symbol received higher trust ratings and increased acceptance. The presentation of automation uncertaintythrough a symbol improves overall driver-automation cooperation. Most automated systems in driving could benefit from displaying reliability information. This display might improve the acceptance of fallible systems and further enhances driver-automation cooperation.

New Directions in Health Risk Assessment: A REACH for the Future?

EPA Science Inventory

Health risk assessments have been used to support many decisions in the US to reduce risks from pollutant exposures. These decisions have been highly successful in protecting public health despite uncertainty due to gaps in knowledge and methodological limitations. In recent yea...

Application of Toxicogenomics in Decision Making in Ecological and Human Health Risk Assessment

EPA Science Inventory

Uncertainties in risk assessment arise from sparse or inadequate data including gaps in our understanding of mode of action, the exposure-dose-response pathway, cross-species toxicokinetic and toxicodynamic information, and/or exposure data. There is an expectation that toxicogen...

REDUCING UNCERTAINTIES IN CHEMICAL MECHANISMS OF AROMATIC AND BIOGENIC HYDROCARBONS

EPA Science Inventory

The state of science in ozone chemistry was reviewed recently in a series of journal reports published under the auspices of the North American Research Strategy for Tropospheric Ozone (NARSTO) in Atmospheric Environment. Included in the NARSTO reports are research gaps that ne...

Generalized Read-Across (GenRA) prediction using chemical and biological information (BOSC)

EPA Science Inventory

Read-across is a popular data gap filling technique within category and analogue approaches for regulatory purposes. Acceptance of read-across remains a challenge with several efforts underway for identifying and addressing uncertainties. To date, these approaches have been quali...

Gap state charge induced spin-dependent negative differential resistance in tunnel junctions

NASA Astrophysics Data System (ADS)

Jiang, Jun; Zhang, X.-G.; Han, X. F.

2016-04-01

We propose and demonstrate through first-principles calculation a new spin-dependent negative differential resistance (NDR) mechanism in magnetic tunnel junctions (MTJ) with cubic cation disordered crystals (CCDC) AlO x or Mg1-x Al x O as barrier materials. The CCDC is a class of insulators whose band gap can be changed by cation doping. The gap becomes arched in an ultrathin layer due to the space charge formed from metal-induced gap states. With an appropriate combination of an arched gap and a bias voltage, NDR can be produced in either spin channel. This mechanism is applicable to 2D and 3D ultrathin junctions with a sufficiently small band gap that forms a large space charge. It provides a new way of controlling the spin-dependent transport in spintronic devices by an electric field. A generalized Simmons formula for tunneling current through junction with an arched gap is derived to show the general conditions under which ultrathin junctions may exhibit NDR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bailey, J.E.; Adams, R.; Carlson, A.L.

Stark-shift measurements using emission spectroscopy are a powerful tool for advancing understanding in many plasma physics experiments. The authors use simultaneous 2-D-spatial and time-resolved spectra to study the electric field evolution in the 20 TW Particle Beam Fusion Accelerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a multiplexed mode that enables recording time-resolved spectra from eight spatial locations on a single instrument. Design optimization and characterization measurements of the multiplexed spectrograph properties include the astigmatism, resolution, dispersion variation, and sensitivity. A semi-automated line-fitting procedure determines the Stark shiftmore » and the related uncertainties. Fields up to 10 MV/cm are measured with an accuracy {+-}2--4%. Detailed tests of the fitting procedure confirm that the wavelength shift uncertainties are accurate to better than {+-}20%. Development of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain 3-D space- and time-resolved measurements of the electric and magnetic fields is in progress.« less

The Iquique earthquake sequence of April 2014: Bayesian modeling accounting for prediction uncertainty

USGS Publications Warehouse

Duputel, Zacharie; Jiang, Junle; Jolivet, Romain; Simons, Mark; Rivera, Luis; Ampuero, Jean-Paul; Riel, Bryan; Owen, Susan E; Moore, Angelyn W; Samsonov, Sergey V; Ortega Culaciati, Francisco; Minson, Sarah E.

2016-01-01

The subduction zone in northern Chile is a well-identified seismic gap that last ruptured in 1877. On 1 April 2014, this region was struck by a large earthquake following a two week long series of foreshocks. This study combines a wide range of observations, including geodetic, tsunami, and seismic data, to produce a reliable kinematic slip model of the Mw=8.1 main shock and a static slip model of the Mw=7.7 aftershock. We use a novel Bayesian modeling approach that accounts for uncertainty in the Green's functions, both static and dynamic, while avoiding nonphysical regularization. The results reveal a sharp slip zone, more compact than previously thought, located downdip of the foreshock sequence and updip of high-frequency sources inferred by back-projection analysis. Both the main shock and the Mw=7.7 aftershock did not rupture to the trench and left most of the seismic gap unbroken, leaving the possibility of a future large earthquake in the region.

Is the Precautionary Principle Really Incoherent?

PubMed

Boyer-Kassem, Thomas

2017-11-01

The Precautionary Principle has been an increasingly important principle in international treaties since the 1980s. Through varying formulations, it states that when an activity can lead to a catastrophe for human health or the environment, measures should be taken to prevent it even if the cause-and-effect relationship is not fully established scientifically. The Precautionary Principle has been critically discussed from many sides. This article concentrates on a theoretical argument by Peterson (2006) according to which the Precautionary Principle is incoherent with other desiderata of rational decision making, and thus cannot be used as a decision rule that selects an action among several ones. I claim here that Peterson's argument fails to establish the incoherence of the Precautionary Principle, by attacking three of its premises. I argue (i) that Peterson's treatment of uncertainties lacks generality, (ii) that his Archimedian condition is problematic for incommensurability reasons, and (iii) that his explication of the Precautionary Principle is not adequate. This leads me to conjecture that the Precautionary Principle can be envisaged as a coherent decision rule, again. © 2017 Society for Risk Analysis.

Constrained sampling experiments reveal principles of detection in natural scenes.

PubMed

Sebastian, Stephen; Abrams, Jared; Geisler, Wilson S

2017-07-11

A fundamental everyday visual task is to detect target objects within a background scene. Using relatively simple stimuli, vision science has identified several major factors that affect detection thresholds, including the luminance of the background, the contrast of the background, the spatial similarity of the background to the target, and uncertainty due to random variations in the properties of the background and in the amplitude of the target. Here we use an experimental approach based on constrained sampling from multidimensional histograms of natural stimuli, together with a theoretical analysis based on signal detection theory, to discover how these factors affect detection in natural scenes. We sorted a large collection of natural image backgrounds into multidimensional histograms, where each bin corresponds to a particular luminance, contrast, and similarity. Detection thresholds were measured for a subset of bins spanning the space, where a natural background was randomly sampled from a bin on each trial. In low-uncertainty conditions, both the background bin and the amplitude of the target were fixed, and, in high-uncertainty conditions, they varied randomly on each trial. We found that thresholds increase approximately linearly along all three dimensions and that detection accuracy is unaffected by background bin and target amplitude uncertainty. The results are predicted from first principles by a normalized matched-template detector, where the dynamic normalizing gain factor follows directly from the statistical properties of the natural backgrounds. The results provide an explanation for classic laws of psychophysics and their underlying neural mechanisms.

Gapped electronic structure of epitaxial stanene on InSb(111)

DOE PAGES

Xu, Cai-Zhi; Chan, Yang-Hao; Chen, Peng; ...

2018-01-11

We report that stanene (single-layer gray tin), with an electronic structure akin to that of graphene but exhibiting a much larger spin-orbit gap, offers a promising platform for room-temperature electronics based on the quantum spin Hall (QSH) effect. This material has received much theoretical attention, but a suitable substrate for stanene growth that results in an overall gapped electronic structure has been elusive; a sizable gap is necessary for room-temperature applications. Here, we report a study of stanene, epitaxially grown on the (111)B-face of indium antimonide (InSb). Angle-resolved photoemission spectroscopy measurements reveal a gap of 0.44 eV, in agreement withmore » our first-principles calculations. Lastly, the results indicate that stanene on InSb(111) is a strong contender for electronic QSH applications.« less

Gapped electronic structure of epitaxial stanene on InSb(111)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Cai-Zhi; Chan, Yang-Hao; Chen, Peng

We report that stanene (single-layer gray tin), with an electronic structure akin to that of graphene but exhibiting a much larger spin-orbit gap, offers a promising platform for room-temperature electronics based on the quantum spin Hall (QSH) effect. This material has received much theoretical attention, but a suitable substrate for stanene growth that results in an overall gapped electronic structure has been elusive; a sizable gap is necessary for room-temperature applications. Here, we report a study of stanene, epitaxially grown on the (111)B-face of indium antimonide (InSb). Angle-resolved photoemission spectroscopy measurements reveal a gap of 0.44 eV, in agreement withmore » our first-principles calculations. Lastly, the results indicate that stanene on InSb(111) is a strong contender for electronic QSH applications.« less

Uncertainty in Bohr's response to the Heisenberg microscope

NASA Astrophysics Data System (ADS)

Tanona, Scott

2004-09-01

In this paper, I analyze Bohr's account of the uncertainty relations in Heisenberg's gamma-ray microscope thought experiment and address the question of whether Bohr thought uncertainty was epistemological or ontological. Bohr's account seems to allow that the electron being investigated has definite properties which we cannot measure, but other parts of his Como lecture seem to indicate that he thought that electrons are wave-packets which do not have well-defined properties. I argue that his account merges the ontological and epistemological aspects of uncertainty. However, Bohr reached this conclusion not from positivism, as perhaps Heisenberg did, but because he was led to that conclusion by his understanding of the physics in terms of nonseparability and the correspondence principle. Bohr argued that the wave theory from which he derived the uncertainty relations was not to be taken literally, but rather symbolically, as an expression of the limited applicability of classical concepts to parts of entangled quantum systems. Complementarity and uncertainty are consequences of the formalism, properly interpreted, and not something brought to the physics from external philosophical views.

Energy band gaps in graphene nanoribbons with corners

NASA Astrophysics Data System (ADS)

Szczȩśniak, Dominik; Durajski, Artur P.; Khater, Antoine; Ghader, Doried

2016-05-01

In the present paper, we study the relation between the band gap size and the corner-corner length in representative chevron-shaped graphene nanoribbons (CGNRs) with 120° and 150° corner edges. The direct physical insight into the electronic properties of CGNRs is provided within the tight-binding model with phenomenological edge parameters, developed against recent first-principle results. We show that the analyzed CGNRs exhibit inverse relation between their band gaps and corner-corner lengths, and that they do not present a metal-insulator transition when the chemical edge modifications are introduced. Our results also suggest that the band gap width for the CGNRs is predominantly governed by the armchair edge effects, and is tunable through edge modifications with foreign atoms dressing.

Electronic structure of graphene- and BN-supported phosphorene

NASA Astrophysics Data System (ADS)

Davletshin, Artur R.; Ustiuzhanina, Svetlana V.; Kistanov, Andrey A.; Saadatmand, Danial; Dmitriev, Sergey V.; Zhou, Kun; Korznikova, Elena A.

2018-04-01

By using first-principles calculations, the effects of graphene and boron nitride (BN) substrates on the electronic properties of phosphorene are studied. Graphene-supported phosphorene is found to be metallic, while the BN-supported phosphorene is a semiconductor with a moderate band gap of 1.02 eV. Furthermore, the effects of the van der Waals interactions between the phosphorene and graphene or BN layers by means of the interlayer distance change are investigated. It is shown that the interlayer distance change leads to significant band gap size modulations and direct-indirect band gap transitions in the phosphorene-BN heterostructure. The presented band gap engineering of phosphorene may be a powerful technique for the fabrication of high-performance phosphorene-based nanodevices.

Adaptive approaches to biosecurity governance.

PubMed

Cook, David C; Liu, Shuang; Murphy, Brendan; Lonsdale, W Mark

2010-09-01

This article discusses institutional changes that may facilitate an adaptive approach to biosecurity risk management where governance is viewed as a multidisciplinary, interactive experiment acknowledging uncertainty. Using the principles of adaptive governance, evolved from institutional theory, we explore how the concepts of lateral information flows, incentive alignment, and policy experimentation might shape Australia's invasive species defense mechanisms. We suggest design principles for biosecurity policies emphasizing overlapping complementary response capabilities and the sharing of invasive species risks via a polycentric system of governance. © 2010 Society for Risk Analysis

Scenario-based fitted Q-iteration for adaptive control of water reservoir systems under uncertainty

NASA Astrophysics Data System (ADS)

Bertoni, Federica; Giuliani, Matteo; Castelletti, Andrea

2017-04-01

Over recent years, mathematical models have largely been used to support planning and management of water resources systems. Yet, the increasing uncertainties in their inputs - due to increased variability in the hydrological regimes - are a major challenge to the optimal operations of these systems. Such uncertainty, boosted by projected changing climate, violates the stationarity principle generally used for describing hydro-meteorological processes, which assumes time persisting statistical characteristics of a given variable as inferred by historical data. As this principle is unlikely to be valid in the future, the probability density function used for modeling stochastic disturbances (e.g., inflows) becomes an additional uncertain parameter of the problem, which can be described in a deterministic and set-membership based fashion. This study contributes a novel method for designing optimal, adaptive policies for controlling water reservoir systems under climate-related uncertainty. The proposed method, called scenario-based Fitted Q-Iteration (sFQI), extends the original Fitted Q-Iteration algorithm by enlarging the state space to include the space of the uncertain system's parameters (i.e., the uncertain climate scenarios). As a result, sFQI embeds the set-membership uncertainty of the future inflow scenarios in the action-value function and is able to approximate, with a single learning process, the optimal control policy associated to any scenario included in the uncertainty set. The method is demonstrated on a synthetic water system, consisting of a regulated lake operated for ensuring reliable water supply to downstream users. Numerical results show that the sFQI algorithm successfully identifies adaptive solutions to operate the system under different inflow scenarios, which outperform the control policy designed under historical conditions. Moreover, the sFQI policy generalizes over inflow scenarios not directly experienced during the policy design, thus alleviating the risk of mis-adaptation, namely the design of a solution fully adapted to a scenario that is different from the one that will actually realize.

Quantum Mechanics predicts evolutionary biology.

PubMed

Torday, J S

2018-07-01

Nowhere are the shortcomings of conventional descriptive biology more evident than in the literature on Quantum Biology. In the on-going effort to apply Quantum Mechanics to evolutionary biology, merging Quantum Mechanics with the fundamentals of evolution as the First Principles of Physiology-namely negentropy, chemiosmosis and homeostasis-offers an authentic opportunity to understand how and why physics constitutes the basic principles of biology. Negentropy and chemiosmosis confer determinism on the unicell, whereas homeostasis constitutes Free Will because it offers a probabilistic range of physiologic set points. Similarly, on this basis several principles of Quantum Mechanics also apply directly to biology. The Pauli Exclusion Principle is both deterministic and probabilistic, whereas non-localization and the Heisenberg Uncertainty Principle are both probabilistic, providing the long-sought after ontologic and causal continuum from physics to biology and evolution as the holistic integration recognized as consciousness for the first time. Copyright © 2018 Elsevier Ltd. All rights reserved.

Robustness of Thirty Meter Telescope primary mirror control

NASA Astrophysics Data System (ADS)

Macmynowski, Douglas G.; Thompson, Peter M.; Shelton, Chris; Roberts, Lewis C., Jr.

2010-07-01

The primary mirror control system for the Thirty Meter Telescope (TMT) maintains the alignment of the 492 segments in the presence of both quasi-static (gravity and thermal) and dynamic disturbances due to unsteady wind loads. The latter results in a desired control bandwidth of 1Hz at high spatial frequencies. The achievable bandwidth is limited by robustness to (i) uncertain telescope structural dynamics (control-structure interaction) and (ii) small perturbations in the ill-conditioned influence matrix that relates segment edge sensor response to actuator commands. Both of these effects are considered herein using models of TMT. The former is explored through multivariable sensitivity analysis on a reduced-order Zernike-basis representation of the structural dynamics. The interaction matrix ("A-matrix") uncertainty has been analyzed theoretically elsewhere, and is examined here for realistic amplitude perturbations due to segment and sensor installation errors, and gravity and thermal induced segment motion. The primary influence of A-matrix uncertainty is on the control of "focusmode"; this is the least observable mode, measurable only through the edge-sensor (gap-dependent) sensitivity to the dihedral angle between segments. Accurately estimating focus-mode will require updating the A-matrix as a function of the measured gap. A-matrix uncertainty also results in a higher gain-margin requirement for focus-mode, and hence the A-matrix and CSI robustness need to be understood simultaneously. Based on the robustness analysis, the desired 1 Hz bandwidth is achievable in the presence of uncertainty for all except the lowest spatial-frequency response patterns of the primary mirror.

Uncertainty Analysis of Thermal Comfort Parameters

NASA Astrophysics Data System (ADS)

Ribeiro, A. Silva; Alves e Sousa, J.; Cox, Maurice G.; Forbes, Alistair B.; Matias, L. Cordeiro; Martins, L. Lages

2015-08-01

International Standard ISO 7730:2005 defines thermal comfort as that condition of mind that expresses the degree of satisfaction with the thermal environment. Although this definition is inevitably subjective, the Standard gives formulae for two thermal comfort indices, predicted mean vote ( PMV) and predicted percentage dissatisfied ( PPD). The PMV formula is based on principles of heat balance and experimental data collected in a controlled climate chamber under steady-state conditions. The PPD formula depends only on PMV. Although these formulae are widely recognized and adopted, little has been done to establish measurement uncertainties associated with their use, bearing in mind that the formulae depend on measured values and tabulated values given to limited numerical accuracy. Knowledge of these uncertainties are invaluable when values provided by the formulae are used in making decisions in various health and civil engineering situations. This paper examines these formulae, giving a general mechanism for evaluating the uncertainties associated with values of the quantities on which the formulae depend. Further, consideration is given to the propagation of these uncertainties through the formulae to provide uncertainties associated with the values obtained for the indices. Current international guidance on uncertainty evaluation is utilized.

Towards traceability in CO2 line strength measurements by TDLAS at 2.7 µm

NASA Astrophysics Data System (ADS)

Pogány, Andrea; Ott, Oliver; Werhahn, Olav; Ebert, Volker

2013-11-01

Direct tunable diode laser absorption spectroscopy (TDLAS) was combined in this study with metrological principles on the determination of uncertainties to measure the line strengths of the P36e and P34e line of 12C16O2 in the ν1+ν3 band at 2.7 μm. Special emphasis was put on traceability and a concise, well-documented uncertainty assessment. We have quantitatively analyzed the uncertainty contributions of different experimental parameters to the uncertainty of the line strength. Establishment of the wavenumber axis and the gas handling procedure proved to be the two major contributors to the final uncertainty. The obtained line strengths at 296 K are 1.593×10-20 cm/molecule for the P36e and 1.981×10-20 cm/molecule for the P34e line, with relative expanded uncertainties of 1.1% and 1.3%, respectively (k=2, corresponding to a 95% confidence level). The measured line strength values are in agreement with literature data (line strengths listed in the HITRAN and GEISA databases), but show an uncertainty, which is at least a factor of 2 lower.

Interpreting null results from measurements with uncertain correlations: an info-gap approach.

PubMed

Ben-Haim, Yakov

2011-01-01

Null events—not detecting a pernicious agent—are the basis for declaring the agent is absent. Repeated nulls strengthen confidence in the declaration. However, correlations between observations are difficult to assess in many situations and introduce uncertainty in interpreting repeated nulls. We quantify uncertain correlations using an info-gap model, which is an unbounded family of nested sets of possible probabilities. An info-gap model is nonprobabilistic and entails no assumption about a worst case. We then evaluate the robustness, to uncertain correlations, of estimates of the probability of a null event. This is then the basis for evaluating a nonprobabilistic robustness-based confidence interval for the probability of a null. © 2010 Society for Risk Analysis.

Probabilistic Risk Assessment to Inform Decision Making: Frequently Asked Questions

EPA Pesticide Factsheets

General concepts and principles of Probabilistic Risk Assessment (PRA), describe how PRA can improve the bases of Agency decisions, and provide illustrations of how PRA has been used in risk estimation and in describing the uncertainty in decision making.

Monolayer Boron Nitride Substrate Interactions with Graphene Under In-Plane and Perpendicular Strains: A First-Principles Study

NASA Astrophysics Data System (ADS)

Behzad, Somayeh

2018-04-01

Effects of strain on the electronic and optical properties of graphene on monolayer boron nitride (BN) substrate are investigated using first-principle calculations based on density functional theory. Strain-free graphene/BN has a small band gap of 97 meV at the K point. The magnitude of band gap increases with in-plane biaxial strain while it decreases with the perpendicular uniaxial strain. The ɛ2 (ω ) spectrum of graphene/BN bilayer for parallel polarization shows red and blue shifts by applying the in-plane tensile and compressive strains, respectively. Also the positions of peaks in the ɛ2 (ω ) spectrum are not significantly changed under perpendicular strain. The calculated results indicate that graphene on the BN substrate has great potential in microelectronic and optoelectronic applications.

First-Principle Electronic Properties of Dilute-P GaN(1-x)P(x) Alloy for Visible Light Emitters.

PubMed

Tan, Chee-Keong; Borovac, Damir; Sun, Wei; Tansu, Nelson

2016-04-14

A study on the electronic properties of the dilute-P GaN(1-x)P(x)alloy using First-Principle Density Functional Theory (DFT) calculations is presented. Our results indicate a band gap energy coverage from 3.645 eV to 2.697 eV, with P-content varying from 0% to 12.5% respectively. In addition, through line fitting of calculated and experimental data, a bowing parameter of 9.5 ± 0.5 eV was obtained. The effective masses for electrons and holes are analyzed, as well as the split-off energy parameters where findings indicate minimal interband Auger recombination. The alloy also possesses the direct energy band gap property, indicating its strong potential as a candidate for future photonic device applications.

The Effect of High N-DOPED Anatase TiO2 on the Band Gap Narrowing and Redshift by First-Principles

NASA Astrophysics Data System (ADS)

Hou, Qingyu; Jin, Yongjun; Ying, Chun; Zhao, Erjun; Zhang, Yue; Dong, Hongying

2012-10-01

Anatase TiO2 supercells were studied by first-principles, in which one was undoped and another three were high N-doping. Partial densities of states, band structure, population and absorption spectrum were calculated. The calculated results indicated that in the condition of TiO2-xNx (x = 0.0625, 0.125, 0.25), the higher the doping concentration is, the shorter will be the lattice parameters parallel to the direction of c-axis. The strength of covalent bond significantly varied. The formation energy increases at first, and then decreases. The doping models become less stable as N-doping concentration increases. Meanwhile, the narrower the band gap is, the more significant will be the redshift, which is in agreement with the experimental results.

The precautionary principle and pharmaceutical risk management.

PubMed

Callréus, Torbjörn

2005-01-01

Although it is often vigorously contested and has several different formulations, the precautionary principle has in recent decades guided environmental policy making in the face of scientific uncertainty. Originating from a criticism of traditional risk assessment, the key element of the precautionary principle is the justification for acting in the face of uncertain knowledge about risks. In the light of its growing invocation in various areas that are related to public health and recently in relation to drug safety issues, this article presents an introductory review of the main elements of the precautionary principle and some arguments conveyed by its advocates and opponents. A comparison of the characteristics of pharmaceutical risk management and environmental policy making (i.e. the setting within which the precautionary principle evolved), indicates that several important differences exist. If believed to be of relevance, in order to avoid arbitrary and unpredictable decision making, both the interpretation and possible application of the precautionary principle need to be adapted to the conditions of pharmaceutical risk management.

Application of fuzzy system theory in addressing the presence of uncertainties

NASA Astrophysics Data System (ADS)

Yusmye, A. Y. N.; Goh, B. Y.; Adnan, N. F.; Ariffin, A. K.

2015-02-01

In this paper, the combinations of fuzzy system theory with the finite element methods are present and discuss to deal with the uncertainties. The present of uncertainties is needed to avoid for prevent the failure of the material in engineering. There are three types of uncertainties, which are stochastic, epistemic and error uncertainties. In this paper, the epistemic uncertainties have been considered. For the epistemic uncertainty, it exists as a result of incomplete information and lack of knowledge or data. Fuzzy system theory is a non-probabilistic method, and this method is most appropriate to interpret the uncertainty compared to statistical approach when the deal with the lack of data. Fuzzy system theory contains a number of processes started from converting the crisp input to fuzzy input through fuzzification process and followed by the main process known as mapping process. The term mapping here means that the logical relationship between two or more entities. In this study, the fuzzy inputs are numerically integrated based on extension principle method. In the final stage, the defuzzification process is implemented. Defuzzification is an important process to allow the conversion of the fuzzy output to crisp outputs. Several illustrative examples are given and from the simulation, the result showed that propose the method produces more conservative results comparing with the conventional finite element method.

Environmental impact and risk assessments and key factors contributing to the overall uncertainties.

PubMed

Salbu, Brit

2016-01-01

There is a significant number of nuclear and radiological sources that have contributed, are still contributing, or have the potential to contribute to radioactive contamination of the environment in the future. To protect the environment from radioactive contamination, impact and risk assessments are performed prior to or during a release event, short or long term after deposition or prior and after implementation of countermeasures. When environmental impact and risks are assessed, however, a series of factors will contribute to the overall uncertainties. To provide environmental impact and risk assessments, information on processes, kinetics and a series of input variables is needed. Adding problems such as variability, questionable assumptions, gaps in knowledge, extrapolations and poor conceptual model structures, a series of factors are contributing to large and often unacceptable uncertainties in impact and risk assessments. Information on the source term and the release scenario is an essential starting point in impact and risk models; the source determines activity concentrations and atom ratios of radionuclides released, while the release scenario determine the physico-chemical forms of released radionuclides such as particle size distribution, structure and density. Releases will most often contain other contaminants such as metals, and due to interactions, contaminated sites should be assessed as a multiple stressor scenario. Following deposition, a series of stressors, interactions and processes will influence the ecosystem transfer of radionuclide species and thereby influence biological uptake (toxicokinetics) and responses (toxicodynamics) in exposed organisms. Due to the variety of biological species, extrapolation is frequently needed to fill gaps in knowledge e.g., from effects to no effects, from effects in one organism to others, from one stressor to mixtures. Most toxtests are, however, performed as short term exposure of adult organisms, ignoring sensitive history life stages of organisms and transgenerational effects. To link sources, ecosystem transfer and biological effects to future impact and risks, a series of models are usually interfaced, while uncertainty estimates are seldom given. The model predictions are, however, only valid within the boundaries of the overall uncertainties. Furthermore, the model predictions are only useful and relevant when uncertainties are estimated, communicated and understood. Among key factors contributing most to uncertainties, the present paper focuses especially on structure uncertainties (model bias or discrepancies) as aspects such as particle releases, ecosystem dynamics, mixed exposure, sensitive life history stages and transgenerational effects, are usually ignored in assessment models. Research focus on these aspects should significantly reduce the overall uncertainties in the impact and risk assessment of radioactive contaminated ecosystems. Copyright © 2015 Elsevier Ltd. All rights reserved.

Optimal Wind Power Uncertainty Intervals for Electricity Market Operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ying; Zhou, Zhi; Botterud, Audun

It is important to select an appropriate uncertainty level of the wind power forecast for power system scheduling and electricity market operation. Traditional methods hedge against a predefined level of wind power uncertainty, such as a specific confidence interval or uncertainty set, which leaves the questions of how to best select the appropriate uncertainty levels. To bridge this gap, this paper proposes a model to optimize the forecast uncertainty intervals of wind power for power system scheduling problems, with the aim of achieving the best trade-off between economics and reliability. Then we reformulate and linearize the models into a mixedmore » integer linear programming (MILP) without strong assumptions on the shape of the probability distribution. In order to invest the impacts on cost, reliability, and prices in a electricity market, we apply the proposed model on a twosettlement electricity market based on a six-bus test system and on a power system representing the U.S. state of Illinois. The results show that the proposed method can not only help to balance the economics and reliability of the power system scheduling, but also help to stabilize the energy prices in electricity market operation.« less

Uncertainty in quantum mechanics: faith or fantasy?

PubMed

Penrose, Roger

2011-12-13

The word 'uncertainty', in the context of quantum mechanics, usually evokes an impression of an essential unknowability of what might actually be going on at the quantum level of activity, as is made explicit in Heisenberg's uncertainty principle, and in the fact that the theory normally provides only probabilities for the results of quantum measurement. These issues limit our ultimate understanding of the behaviour of things, if we take quantum mechanics to represent an absolute truth. But they do not cause us to put that very 'truth' into question. This article addresses the issue of quantum 'uncertainty' from a different perspective, raising the question of whether this term might be applied to the theory itself, despite its unrefuted huge success over an enormously diverse range of observed phenomena. There are, indeed, seeming internal contradictions in the theory that lead us to infer that a total faith in it at all levels of scale leads us to almost fantastical implications.

Fundamental uncertainty limit for speckle displacement measurements.

PubMed

Fischer, Andreas

2017-09-01

The basic metrological task in speckle photography is to quantify displacements of speckle patterns, allowing for instance the investigation of the mechanical load and modification of objects with rough surfaces. However, the fundamental limit of the measurement uncertainty due to photon shot noise is unknown. For this reason, the Cramér-Rao bound (CRB) is derived for speckle displacement measurements, representing the squared minimal achievable measurement uncertainty. As result, the CRB for speckle patterns is only two times the CRB for an ideal point light source. Hence, speckle photography is an optimal measurement approach for contactless displacement measurements on rough surfaces. In agreement with a derivation from Heisenberg's uncertainty principle, the CRB depends on the number of detected photons and the diffraction limit of the imaging system described by the speckle size. The theoretical results are verified and validated, demonstrating the capability for displacement measurements with nanometer resolution.

COMMUNICATING THE PARAMETER UNCERTAINTY IN THE IQWIG EFFICIENCY FRONTIER TO DECISION-MAKERS

PubMed Central

Stollenwerk, Björn; Lhachimi, Stefan K; Briggs, Andrew; Fenwick, Elisabeth; Caro, Jaime J; Siebert, Uwe; Danner, Marion; Gerber-Grote, Andreas

2015-01-01

The Institute for Quality and Efficiency in Health Care (IQWiG) developed—in a consultation process with an international expert panel—the efficiency frontier (EF) approach to satisfy a range of legal requirements for economic evaluation in Germany's statutory health insurance system. The EF approach is distinctly different from other health economic approaches. Here, we evaluate established tools for assessing and communicating parameter uncertainty in terms of their applicability to the EF approach. Among these are tools that perform the following: (i) graphically display overall uncertainty within the IQWiG EF (scatter plots, confidence bands, and contour plots) and (ii) communicate the uncertainty around the reimbursable price. We found that, within the EF approach, most established plots were not always easy to interpret. Hence, we propose the use of price reimbursement acceptability curves—a modification of the well-known cost-effectiveness acceptability curves. Furthermore, it emerges that the net monetary benefit allows an intuitive interpretation of parameter uncertainty within the EF approach. This research closes a gap for handling uncertainty in the economic evaluation approach of the IQWiG methods when using the EF. However, the precise consequences of uncertainty when determining prices are yet to be defined. © 2014 The Authors. Health Economics published by John Wiley & Sons Ltd. PMID:24590819

Dynamical Stability of Imaged Planetary Systems in Formation: Application to HL Tau

NASA Astrophysics Data System (ADS)

Tamayo, D.; Triaud, A. H. M. J.; Menou, K.; Rein, H.

2015-06-01

A recent Atacama Large Millimeter/Submillimeter Array image revealed several concentric gaps in the protoplanetary disk surrounding the young star HL Tau. We consider the hypothesis that these gaps are carved by planets, and present a general framework for understanding the dynamical stability of such systems over typical disk lifetimes, providing estimates for the maximum planetary masses. We collect these easily evaluated constraints into a workflow that can help guide the design and interpretation of new observational campaigns and numerical simulations of gap opening in such systems. We argue that the locations of resonances should be significantly shifted in massive disks like HL Tau, and that theoretical uncertainties in the exact offset, together with observational errors, imply a large uncertainty in the dynamical state and stability in such disks. This presents an important barrier to using systems like HL Tau as a proxy for the initial conditions following planet formation. An important observational avenue to breaking this degeneracy is to search for eccentric gaps, which could implicate resonantly interacting planets. Unfortunately, massive disks like HL Tau should induce swift pericenter precession that would smear out any such eccentric features of planetary origin. This motivates pushing toward more typical, less massive disks. For a nominal non-resonant model of the HL Tau system with five planets, we find a maximum mass for the outer three bodies of approximately 2 Neptune masses. In a resonant configuration, these planets can reach at least the mass of Saturn. The inner two planets’ masses are unconstrained by dynamical stability arguments.

The actual content of quantum theoretical kinematics and mechanics

NASA Technical Reports Server (NTRS)

Heisenberg, W.

1983-01-01

First, exact definitions are supplied for the terms: position, velocity, energy, etc. (of the electron, for instance), such that they are valid also in quantum mechanics. Canonically conjugated variables are determined simultaneously only with a characteristic uncertainty. This uncertainty is the intrinsic reason for the occurrence of statistical relations in quantum mechanics. Mathematical formulation is made possible by the Dirac-Jordan theory. Beginning from the basic principles thus obtained, macroscopic processes are understood from the viewpoint of quantum mechanics. Several imaginary experiments are discussed to elucidate the theory.

Mass Uncertainty and Application For Space Systems

NASA Technical Reports Server (NTRS)

Beech, Geoffrey

2013-01-01

Expected development maturity under contract (spec) should correlate with Project/Program Approved MGA Depletion Schedule in Mass Properties Control Plan. If specification NTE, MGA is inclusive of Actual MGA (A5 & A6). If specification is not an NTE Actual MGA (e.g. nominal), then MGA values are reduced by A5 values and A5 is representative of remaining uncertainty. Basic Mass = Engineering Estimate based on design and construction principles with NO embedded margin MGA Mass = Basic Mass * assessed % from approved MGA schedule. Predicted Mass = Basic + MGA. Aggregate MGA % = (Aggregate Predicted - Aggregate Basic) /Aggregate Basic.

How do local stakeholders respond to the uncertain implications of an innovative flood infrastructure project?

NASA Astrophysics Data System (ADS)

van den Hoek, Ronald; Brugnach, Marcela; Hoekstra, Arjen

2013-04-01

In the 20th century, flood management was dominated by rigid structures - such as dikes and dams - which intend to strictly regulate and control water systems. Although the application of these rigid structures has been successful in the recent past, their negative implications for ecosystems and natural processes is often not properly taken into account. Therefore, flood management practices are currently moving towards more nature-inclusive approaches. Building with Nature (BwN) is such a new approach of nature-inclusive flood management in the Netherlands, which aims to utilize natural dynamics (e.g., wind and currents) and natural materials (e.g., sediment and vegetation) for the realization of effective flood infrastructure, while providing opportunities for nature development. However, the natural dynamics driving a project based on BwN design principles are inherently unpredictable. Furthermore, our factual knowledge base regarding the socio-ecological system in which the BwN initiative is implemented is incomplete. Moreover, in recent years, it is increasingly aimed for by decision-makers to involve local stakeholders in the development of promising flood management initiatives. These stakeholders and other actors involved can have diverging views regarding the project, can perceive unanticipated implications and could choose unforeseen action paths. In short, while a project based on BwN design principles - like any human intervention - definitely has implications for the socio-ecological system, both the extent to which these particular implications will occur and the response of stakeholders are highly uncertain. In this paper, we study the Safety Buffer Oyster Dam case - a BwN pilot project - and address the interplay between the project's implications, the uncertainties regarding these implications and the action paths chosen by the local stakeholders and project team. We determine how the implications of the Safety Buffer project are viewed by local stakeholders, identify the frames and uncertainties related to these implications, and classify these uncertainties according to their nature and level. We describe which action paths are chosen by the local stakeholders and project team regarding the implications identified. Our research shows that there is a correspondence between the level of uncertainty about the implications identified and the action paths chosen by the actors involved. This suggests that the inherent deep uncertainty in projects based on BwN principles calls for more adaptable and flexible strategies to cope with the implications of these initiatives.

Feminist Social Work: Practice and Theory of Practice.

PubMed

Eyal-Lubling, Roni; Krumer-Nevo, Michal

2016-07-01

Although feminist social work has been practiced in Israel since the 1970s, little has been written about it. This qualitative study aims to fill this gap by documenting and conceptualizing feminist theory of practice and actual practice based on interviews with 12 feminist social workers. Findings reveal that the interviewees perceive feminist practice as significantly different from traditional social work practice based on four analytical principles: (1) gender analysis, (2) awareness of power relations, (3) analysis of welfare services as structures of oppression, and (4) utilization of feminist language, as well as 10 principles of action. The principles are discussed in the context of feminist social work in Israel and in light of feminist principles described in international literature.

Band gap modulation of graphene by metal substrate: A first principles study

NASA Astrophysics Data System (ADS)

Sahoo, Mihir Ranjan; Sahu, Sivabrata; Kushwaha, Anoop Kumar; Nayak, S. K.

2018-04-01

Due to high in-plane charge carrier mobility with high electron velocity and long spin diffusion length, graphene guarantees as a completely unique material for devices with various applications. Unaffected 2pz orbitals of carbon atoms in graphene can be highly influenced by substrates and leads to tuning in electronic properties. We report here a density functional calculation of graphene monolayer based on metallic substrate like nickel surfaces. Band-gap of graphene near K points opens due to interactions between 2pz and d-orbitals of nickel atoms and the gap modulation can be done with the increasing number of layers of substrates.

The Electronic and Optical Properties of Au Doped Single-Layer Phosphorene

NASA Astrophysics Data System (ADS)

Zhu, Ziqing; Chen, Changpeng; Liu, Jiayi; Han, Lu

2018-01-01

The electronic properties and optical properties of single and double Au-doped phosphorene have been comparatively investigated using the first-principles plane-wave pseudopotential method based on density functional theory. The decrease from direct band gap 0.78 eV to indirect band gap 0.22 and 0.11 eV are observed in the single and double Au-doped phosphorene, respectively. The red shifts of absorbing edge occur in both doped systems, which consequently enhance the absorbing of infrared light in phosphorene. Band gap engineering can, therefore, be used to directly tune the optical absorption of phosphorene system by substitutional Au doping.

Tin monochalcogenide heterostructures as mechanically rigid infrared band gap semiconductors

NASA Astrophysics Data System (ADS)

Özçelik, V. Ongun; Fathi, Mohammad; Azadani, Javad G.; Low, Tony

2018-05-01

Based on first-principles density functional calculations, we show that SnS and SnSe layers can form mechanically rigid heterostructures with the constituent puckered or buckled monolayers. Due to the strong interlayer coupling, the electronic wave functions of the conduction and valence band edges are delocalized across the heterostructure. The resultant band gaps of the heterostructures reside in the infrared region. With strain engineering, the heterostructure band gap undergoes a transition from indirect to direct in the puckered phase. Our results show that there is a direct correlation between the electronic wave function and the mechanical rigidity of the layered heterostructure.

Bridging the gap between theories of sensory cue integration and the physiology of multisensory neurons

PubMed Central

Fetsch, Christopher R.

2013-01-01

The richness of perceptual experience, as well as its usefulness for guiding behavior, depends upon the synthesis of information across multiple senses. Recent decades have witnessed a surge in our understanding of how the brain combines sensory signals, or cues. Much of this research has been guided by one of two distinct approaches, one driven primarily by neurophysiological observations, the other guided by principles of mathematical psychology and psychophysics. Conflicting results and interpretations have contributed to a conceptual gap between psychophysical and physiological accounts of cue integration, but recent studies of visual-vestibular cue integration have narrowed this gap considerably. PMID:23686172

Robert Frost and the Poetry of Physics.

ERIC Educational Resources Information Center

Coletta, W. John; Tamres, David H.

1992-01-01

Examines five poems by Robert Frost that illustrate Frost's interest in science. The poems include allusions to renowned physicists, metaphoric descriptions of some famous physics experiments, explorations of complementarity as enunciated by Bohr, and poetic formulations of Heisenberg's uncertainty principle. (20 references) (MDH)

Closing the Minority Achievement Gap in Math

ERIC Educational Resources Information Center

Holloway, John H.

2004-01-01

Minority students face numerous academic barriers for achievement in the classroom as well as outside the school. The National Council of Teachers of Mathematics (NCTM) suggests six principles for maintaining the standard of school mathematics.

Alternatives to Re-Planning: Methods for Plan Re-Evaluation at Runtime

NASA Technical Reports Server (NTRS)

Benazera, Emmanuel

2005-01-01

Current planning algorithms have difficulty handling the complexity that is due to an increase in domain uncertainty, and especially in the case of multi-dimensional continuous spaces. Therefore, they produce plans that do not take into account numerous situations that can occur at runtime, such as faults or other changes in the planning domain itself. Thus there is a gap between the plan generation and the reality experienced at runtime. Here we present two methods that allow the plan conditionals to be revised w.r.t. uncertainty on the system as estimated at runtime.

Analysis of recent projections of electric power demand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hudson, Jr, D V

1993-08-01

This report reviews the changes and potential changes in the outlook for electric power demand since the publication of Review and Analysis of Electricity Supply Market Projections (B. Swezey, SERI/MR-360-3322, National Renewable Energy Laboratory). Forecasts of the following organizations were reviewed: DOE/Energy Information Administration, DOE/Policy Office, DRI/McGraw-Hill, North American Electric Reliability Council, and Gas Research Institute. Supply uncertainty was briefly reviewed to place the uncertainties of the demand outlook in perspective. Also discussed were opportunities for modular technologies, such as renewable energy technologies, to fill a potential gap in energy demand and supply.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burr, Tom; Croft, Stephen; Jarman, Kenneth D.

The various methods of nondestructive assay (NDA) of special nuclear material (SNM) have applications in nuclear nonproliferation, including detection and identification of illicit SNM at border crossings, and quantifying SNM at nuclear facilities for safeguards. No assay method is complete without “error bars,” which provide one way of expressing confidence in the assay result. Consequently, NDA specialists typically quantify total uncertainty in terms of “random” and “systematic” components, and then specify error bars for the total mass estimate in multiple items. Uncertainty quantification (UQ) for NDA has always been important, but it is recognized that greater rigor is needed andmore » achievable using modern statistical methods. To this end, we describe the extent to which the guideline for expressing uncertainty in measurements (GUM) can be used for NDA. Also, we propose improvements over GUM for NDA by illustrating UQ challenges that it does not address, including calibration with errors in predictors, model error, and item-specific biases. A case study is presented using low-resolution NaI spectra and applying the enrichment meter principle to estimate the U-235 mass in an item. The case study illustrates how to update the current American Society for Testing and Materials guide for application of the enrichment meter principle using gamma spectra from a NaI detector.« less

Self-Interaction Corrected Electronic Structure and Energy Gap of CuAlO2 beyond Local Density Approximation

NASA Astrophysics Data System (ADS)

Nakanishi, Akitaka

2011-05-01

We implemented a self-interaction correction (SIC) into first-principles calculation code to go beyond local density approximation and applied it to CuAlO2. Our simulation shows that the valence band width calculated within the SIC is narrower than that calculated without the SIC because the SIC makes the d-band potential deeper. The energy gap calculated within the SIC expands and is close to experimental data.

The developmental origins of fairness: the knowledge-behavior gap.

PubMed

Blake, Peter R; McAuliffe, Katherine; Warneken, Felix

2014-11-01

Recent research in developmental psychology shows that children understand several principles of fairness by 3 years of age, much earlier than previously believed. However, children's knowledge of fairness does not always align with their behavior, and immediate self-interest alone cannot explain this gap. In this forum paper, we consider two factors that influence the relation between fairness knowledge and behavior: relative advantage and how rewards are acquired. Copyright © 2014 Elsevier Ltd. All rights reserved.

What an open source clinical trial community can learn from hackers

PubMed Central

Dunn, Adam G.; Day, Richard O.; Mandl, Kenneth D.; Coiera, Enrico

2014-01-01

Summary Open sharing of clinical trial data has been proposed as a way to address the gap between the production of clinical evidence and the decision-making of physicians. Since a similar gap has already been addressed in the software industry by the open source software movement, we examine how the social and technical principles of the movement can be used to guide the growth of an open source clinical trial community. PMID:22553248

Effects of the impurity-host interactions on the nonradiative processes in ZnS:Cr

NASA Astrophysics Data System (ADS)

Tablero, C.

2010-11-01

There is a great deal of controversy about whether the behavior of an intermediate band in the gap of semiconductors is similar or not to the deep-gap levels. It can have significant consequences, for example, on the nonradiative recombination. In order to analyze the behavior of an intermediate band, we have considered the effect of the inward and outward displacements corresponding to breathing and longitudinal modes of Cr-doped ZnS and on the charge density for different processes involved in the nonradiative recombination using first-principles. This metal-doped zinc chalcogenide has a partially filled band within the host semiconductor gap. In contrast to the properties exhibited by deep-gap levels in other systems, we find small variations in the equilibrium configurations, forces, and electronic density around the Cr when the nonradiative recombination mechanisms modify the intermediate band charge. The charge density around the impurity is equilibrated in response to the perturbations in the equilibrium nuclear configuration and the charge of the intermediate band. The equilibration follows a Le Chatelier principle through the modification of the contribution from the impurity to the intermediate band and to the valence band. The intermediate band introduced by Cr in ZnS for the concentrations analyzed makes the electronic capture difficult and later multiphonon emission in the charge-transfer processes, in accordance with experimental results.

Strontium ruthenate-anatase titanium dioxide heterojunctions from first-principles: Electronic structure, spin, and interface dipoles

NASA Astrophysics Data System (ADS)

Ferdous, Naheed; Ertekin, Elif

2016-07-01

The epitaxial integration of functional oxides with wide band gap semiconductors offers the possibility of new material systems for electronics and energy conversion applications. We use first principles to consider an epitaxial interface between the correlated metal oxide SrRuO3 and the wide band gap semiconductor TiO2, and assess energy level alignment, interfacial chemistry, and interfacial dipole formation. Due to the ferromagnetic, half-metallic character of SrRuO3, according to which only one spin is present at the Fermi level, we demonstrate the existence of a spin dependent band alignment across the interface. For two different terminations of SrRuO3, the interface is found to be rectifying with a Schottky barrier of ≈1.3-1.6 eV, in good agreement with experiment. In the minority spin, SrRuO3 exhibits a Schottky barrier alignment with TiO2 and our calculated Schottky barrier height is in excellent agreement with previous experimental measurements. For majority spin carriers, we find that SrRuO3 recovers its exchange splitting gap and bulk-like properties within a few monolayers of the interface. These results demonstrate a possible approach to achieve spin-dependent transport across a heteroepitaxial interface between a functional oxide material and a conventional wide band gap semiconductor.

Systematically evaluating read-across prediction and performance using a local validity approach characterized by chemical structure and bioactivity information

EPA Science Inventory

Read-across is a popular data gap filling technique within category and analogue approaches for regulatory purposes. Acceptance of read-across remains an ongoing challenge with several efforts underway for identifying and addressing uncertainties. Here we demonstrate an algorithm...

Improving the Risk Assessment of Persistent, Bioaccumulative, and Toxic (PBT) Chemicals in Breast Milk: Workshop Summary Report

EPA Science Inventory

This report provides a summary of discussions held at an EPA-sponsored workshop in Research Triangle Park, NC in October, 2012. Workshop participants discussed approaches to improve risk assessment of PBT chemicals in breast milk, data gaps, uncertainties, and suggested solutions...

ISSUES AND RECCOMMENDATIONS FOR POREWATER TOXCITY TESTING: METHODOLOGICAL UNCERTAINTIES, CONFOUNDING FACTORS AND TOXCITY IDENTIFICATION EVALUATION PROCEDURES

EPA Science Inventory

During the last decade porewater toxicity tests have gained popularity among researchers and managers as tools for the assessment of the presence and biological effects of bioavailable contaminants in aquatic sediments. However, there are a number of information gaps in our know...

Students' Perceptions regarding Their Impending Transition out of College

ERIC Educational Resources Information Center

Yazedjian, Ani; Kielaszek, Becki J.; Toews, Michelle L.

2010-01-01

Although researchers have argued students experience feelings of stress, fear, and uncertainty as they transition from college to work life, there is limited empirical research supporting this argument. Our study filled this gap by exploring 183 fourth-year students' perceptions regarding their impending transition out of the college environment.…

Dipole-allowed direct band gap silicon superlattices

PubMed Central

Oh, Young Jun; Lee, In-Ho; Kim, Sunghyun; Lee, Jooyoung; Chang, Kee Joo

2015-01-01

Silicon is the most popular material used in electronic devices. However, its poor optical properties owing to its indirect band gap nature limit its usage in optoelectronic devices. Here we present the discovery of super-stable pure-silicon superlattice structures that can serve as promising materials for solar cell applications and can lead to the realization of pure Si-based optoelectronic devices. The structures are almost identical to that of bulk Si except that defective layers are intercalated in the diamond lattice. The superlattices exhibit dipole-allowed direct band gaps as well as indirect band gaps, providing ideal conditions for the investigation of a direct-to-indirect band gap transition. The fact that almost all structural portions of the superlattices originate from bulk Si warrants their stability and good lattice matching with bulk Si. Through first-principles molecular dynamics simulations, we confirmed their thermal stability and propose a possible method to synthesize the defective layer through wafer bonding. PMID:26656482

Research implications of science-informed, value-based decision making.

PubMed

Dowie, Jack

2004-01-01

In 'Hard' science, scientists correctly operate as the 'guardians of certainty', using hypothesis testing formulations and value judgements about error rates and time discounting that make classical inferential methods appropriate. But these methods can neither generate most of the inputs needed by decision makers in their time frame, nor generate them in a form that allows them to be integrated into the decision in an analytically coherent and transparent way. The need for transparent accountability in public decision making under uncertainty and value conflict means the analytical coherence provided by the stochastic Bayesian decision analytic approach, drawing on the outputs of Bayesian science, is needed. If scientific researchers are to play the role they should be playing in informing value-based decision making, they need to see themselves also as 'guardians of uncertainty', ensuring that the best possible current posterior distributions on relevant parameters are made available for decision making, irrespective of the state of the certainty-seeking research. The paper distinguishes the actors employing different technologies in terms of the focus of the technology (knowledge, values, choice); the 'home base' mode of their activity on the cognitive continuum of varying analysis-to-intuition ratios; and the underlying value judgements of the activity (especially error loss functions and time discount rates). Those who propose any principle of decision making other than the banal 'Best Principle', including the 'Precautionary Principle', are properly interpreted as advocates seeking to have their own value judgements and preferences regarding mode location apply. The task for accountable decision makers, and their supporting technologists, is to determine the best course of action under the universal conditions of uncertainty and value difference/conflict.

Cosmological horizons, uncertainty principle, and maximum length quantum mechanics

NASA Astrophysics Data System (ADS)

Perivolaropoulos, L.

2017-05-01

The cosmological particle horizon is the maximum measurable length in the Universe. The existence of such a maximum observable length scale implies a modification of the quantum uncertainty principle. Thus due to nonlocality of quantum mechanics, the global properties of the Universe could produce a signature on the behavior of local quantum systems. A generalized uncertainty principle (GUP) that is consistent with the existence of such a maximum observable length scale lmax is Δ x Δ p ≥ℏ2/1/1 -α Δ x2 where α =lmax-2≃(H0/c )2 (H0 is the Hubble parameter and c is the speed of light). In addition to the existence of a maximum measurable length lmax=1/√{α }, this form of GUP implies also the existence of a minimum measurable momentum pmin=3/√{3 } 4 ℏ√{α }. Using appropriate representation of the position and momentum quantum operators we show that the spectrum of the one-dimensional harmonic oscillator becomes E¯n=2 n +1 +λnα ¯ where E¯n≡2 En/ℏω is the dimensionless properly normalized n th energy level, α ¯ is a dimensionless parameter with α ¯≡α ℏ/m ω and λn˜n2 for n ≫1 (we show the full form of λn in the text). For a typical vibrating diatomic molecule and lmax=c /H0 we find α ¯˜10-77 and therefore for such a system, this effect is beyond the reach of current experiments. However, this effect could be more important in the early Universe and could produce signatures in the primordial perturbation spectrum induced by quantum fluctuations of the inflaton field.

Assessment of Uncertainties for the NIST 1016 mm Guarded-Hot-Plate Apparatus: Extended Analysis for Low-Density Fibrous-Glass Thermal Insulation.

PubMed

Zarr, Robert R

2010-01-01

An assessment of uncertainties for the National Institute of Standards and Technology (NIST) 1016 mm Guarded-Hot-Plate apparatus is presented. The uncertainties are reported in a format consistent with current NIST policy on the expression of measurement uncertainty. The report describes a procedure for determination of component uncertainties for thermal conductivity and thermal resistance for the apparatus under operation in either the double-sided or single-sided mode of operation. An extensive example for computation of uncertainties for the single-sided mode of operation is provided for a low-density fibrous-glass blanket thermal insulation. For this material, the relative expanded uncertainty for thermal resistance increases from 1 % for a thickness of 25.4 mm to 3 % for a thickness of 228.6 mm. Although these uncertainties have been developed for a particular insulation material, the procedure and, to a lesser extent, the results are applicable to other insulation materials measured at a mean temperature close to 297 K (23.9 °C, 75 °F). The analysis identifies dominant components of uncertainty and, thus, potential areas for future improvement in the measurement process. For the NIST 1016 mm Guarded-Hot-Plate apparatus, considerable improvement, especially at higher values of thermal resistance, may be realized by developing better control strategies for guarding that include better measurement techniques for the guard gap thermopile voltage and the temperature sensors.

Assessment of Uncertainties for the NIST 1016 mm Guarded-Hot-Plate Apparatus: Extended Analysis for Low-Density Fibrous-Glass Thermal Insulation

PubMed Central

Zarr, Robert R.

2010-01-01

An assessment of uncertainties for the National Institute of Standards and Technology (NIST) 1016 mm Guarded-Hot-Plate apparatus is presented. The uncertainties are reported in a format consistent with current NIST policy on the expression of measurement uncertainty. The report describes a procedure for determination of component uncertainties for thermal conductivity and thermal resistance for the apparatus under operation in either the double-sided or single-sided mode of operation. An extensive example for computation of uncertainties for the single-sided mode of operation is provided for a low-density fibrous-glass blanket thermal insulation. For this material, the relative expanded uncertainty for thermal resistance increases from 1 % for a thickness of 25.4 mm to 3 % for a thickness of 228.6 mm. Although these uncertainties have been developed for a particular insulation material, the procedure and, to a lesser extent, the results are applicable to other insulation materials measured at a mean temperature close to 297 K (23.9 °C, 75 °F). The analysis identifies dominant components of uncertainty and, thus, potential areas for future improvement in the measurement process. For the NIST 1016 mm Guarded-Hot-Plate apparatus, considerable improvement, especially at higher values of thermal resistance, may be realized by developing better control strategies for guarding that include better measurement techniques for the guard gap thermopile voltage and the temperature sensors. PMID:27134779

Fabrication and characteristics of thin disc piezoelectric transformers based on piezoelectric buzzers with gap circles.

PubMed

Chang, Kuo-Tsai; Lee, Chun-Wei

2008-04-01

This paper investigates design, fabrication and test of thin disc piezoelectric transformers (PTs) based on piezoelectric buzzers with gap circles at different diameters of the gap circles. The performance test is focused on characteristics of voltage gains, including maximum voltage gains and maximum-gain frequencies, for each piezoelectric transformer under different load conditions. Both a piezoelectric buzzer and a gap circle on a silver electrode of the buzzer are needed to build any type of the PTs. Here, the gap circle is used to form a ring-shaped input electrode and a circle-shaped output electrode for each piezoelectric transformer. To do so, both structure and connection of a PT are first expressed. Then, operating principle of a PT and its related vibration mode observed by a carbon-power imaging technique are described. Moreover, an experimental setup for characterizing each piezoelectric transformer is constructed. Finally, effects of diameters of the gap circles on characteristics of voltage gains at different load resistances are discussed.

Optical spectroscopy and band gap analysis of hybrid improper ferroelectric Ca3Ti2O7

NASA Astrophysics Data System (ADS)

Musfeldt, Janice; Cherian, Judy; Birol, Turan; Harms, Nathan; Gao, Bin; Cheong, Sang; Vanderbilt, David

We bring together optical absorption spectroscopy, photoconductivity, and first principles calculations to reveal the electronic structure of the room temperature ferroelectric Ca3Ti2O7. The 3.94 eV direct gap in Ca3Ti2O7 is charge transfer in nature and noticeably higher than that in CaTiO3 (3.4 eV), a finding that we attribute to dimensional confinement in the n = 2 member of the Ruddlesden-Popper series. While Sr substitution introduces disorder and broadens the gap edge slightly, oxygen deficiency reduces the gap to 3.7 eV and gives rise to a broad tail that persists to much lower energies. MSD, BES, U. S. DoE and DMREF, NSF.

Optical spectroscopy and band gap analysis of hybrid improper ferroelectric Ca{sub 3}Ti{sub 2}O{sub 7}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cherian, Judy G.; Harms, Nathan C.; Birol, Turan

2016-06-27

We bring together optical absorption spectroscopy, photoconductivity, and first principles calculations to reveal the electronic structure of the room temperature ferroelectric Ca{sub 3}Ti{sub 2}O{sub 7}. The 3.94 eV direct gap in Ca{sub 3}Ti{sub 2}O{sub 7} is charge transfer in nature and noticeably higher than that in CaTiO{sub 3} (3.4 eV), a finding that we attribute to dimensional confinement in the n = 2 member of the Ruddlesden-Popper series. While Sr substitution introduces disorder and broadens the gap edge slightly, oxygen deficiency reduces the gap to 3.7 eV and gives rise to a broad tail that persists to much lower energies.

Entropic uncertainty for spin-1/2 XXX chains in the presence of inhomogeneous magnetic fields and its steering via weak measurement reversals

NASA Astrophysics Data System (ADS)

Wang, Dong; Ming, Fei; Huang, Ai-Jun; Sun, Wen-Yang; Ye, Liu

2017-09-01

The uncertainty principle configures a low bound to the measuring precision for a pair of non-commuting observables, and hence is considerably nontrivial to quantum precision measurement in the field of quantum information theory. In this letter, we consider the entropic uncertainty relation (EUR) in the context of quantum memory in a two-qubit isotropic Heisenberg spin chain. Specifically, we explore the dynamics of EUR in a practical scenario, where two associated nodes of a one-dimensional XXX-spin chain, under an inhomogeneous magnetic field, are connected to a thermal entanglement. We show that the temperature and magnetic field effect can lead to the inflation of the measuring uncertainty, stemming from the reduction of systematic quantum correlation. Notably, we reveal that, firstly, the uncertainty is not fully dependent on the observed quantum correlation of the system; secondly, the dynamical behaviors of the measuring uncertainty are relatively distinct with respect to ferromagnetism and antiferromagnetism chains. Meanwhile, we deduce that the measuring uncertainty is dramatically correlated with the mixedness of the system, implying that smaller mixedness tends to reduce the uncertainty. Furthermore, we propose an effective strategy to control the uncertainty of interest by means of quantum weak measurement reversal. Therefore, our work may shed light on the dynamics of the measuring uncertainty in the Heisenberg spin chain, and thus be important to quantum precision measurement in various solid-state systems.

Designing nanomaterials to maximize performance and minimize undesirable implications guided by the Principles of Green Chemistry.

PubMed

Gilbertson, Leanne M; Zimmerman, Julie B; Plata, Desiree L; Hutchison, James E; Anastas, Paul T

2015-08-21

The Twelve Principles of Green Chemistry were first published in 1998 and provide a framework that has been adopted not only by chemists, but also by design practitioners and decision-makers (e.g., materials scientists and regulators). The development of the Principles was initially motivated by the need to address decades of unintended environmental pollution and human health impacts from the production and use of hazardous chemicals. Yet, for over a decade now, the Principles have been applied to the synthesis and production of engineered nanomaterials (ENMs) and the products they enable. While the combined efforts of the global scientific community have led to promising advances in the field of nanotechnology, there remain significant research gaps and the opportunity to leverage the potential global economic, societal and environmental benefits of ENMs safely and sustainably. As such, this tutorial review benchmarks the successes to date and identifies critical research gaps to be considered as future opportunities for the community to address. A sustainable material design framework is proposed that emphasizes the importance of establishing structure-property-function (SPF) and structure-property-hazard (SPH) relationships to guide the rational design of ENMs. The goal is to achieve or exceed the functional performance of current materials and the technologies they enable, while minimizing inherent hazard to avoid risk to human health and the environment at all stages of the life cycle.

Weak values, 'negative probability', and the uncertainty principle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolovski, D.

2007-10-15

A quantum transition can be seen as a result of interference between various pathways (e.g., Feynman paths), which can be labeled by a variable f. An attempt to determine the value of f without destroying the coherence between the pathways produces a weak value of f. We show f to be an average obtained with an amplitude distribution which can, in general, take negative values, which, in accordance with the uncertainty principle, need not contain information about the actual range of f which contributes to the transition. It is also demonstrated that the moments of such alternating distributions have amore » number of unusual properties which may lead to a misinterpretation of the weak-measurement results. We provide a detailed analysis of weak measurements with and without post-selection. Examples include the double-slit diffraction experiment, weak von Neumann and von Neumann-like measurements, traversal time for an elastic collision, phase time, and local angular momentum.« less

"He loves me, he loves me not . . . ": uncertainty can increase romantic attraction.

PubMed

Whitchurch, Erin R; Wilson, Timothy D; Gilbert, Daniel T

2011-02-01

This research qualifies a social psychological truism: that people like others who like them (the reciprocity principle). College women viewed the Facebook profiles of four male students who had previously seen their profiles. They were told that the men (a) liked them a lot, (b) liked them only an average amount, or (c) liked them either a lot or an average amount (uncertain condition). Comparison of the first two conditions yielded results consistent with the reciprocity principle. Participants were more attracted to men who liked them a lot than to men who liked them an average amount. Results for the uncertain condition, however, were consistent with research on the pleasures of uncertainty. Participants in the uncertain condition were most attracted to the men-even more attracted than were participants who were told that the men liked them a lot. Uncertain participants reported thinking about the men the most, and this increased their attraction toward the men.

Reliability of ceramics for heat engine applications

NASA Technical Reports Server (NTRS)

1980-01-01

The advantages and disadvantages associated with the use of monolithic ceramics in heat engines are discussed. The principle gaps in the state of understanding of ceramic material, failure origins, nondestructive tests as well as life prediction are included.

Theoretical Prediction of an Antimony-Silicon Monolayer (penta-Sb2Si): Band Gap Engineering by Strain Effect

NASA Astrophysics Data System (ADS)

Morshedi, Hosein; Naseri, Mosayeb; Hantehzadeh, Mohammad Reza; Elahi, Seyed Mohammad

2018-04-01

In this paper, using a first principles calculation, a two-dimensional structure of silicon-antimony named penta-Sb2Si is predicted. The structural, kinetic, and thermal stabilities of the predicted monolayer are confirmed by the cohesive energy calculation, phonon dispersion analysis, and first principles molecular dynamic simulation, respectively. The electronic properties investigation shows that the pentagonal Sb2Si monolayer is a semiconductor with an indirect band gap of about 1.53 eV (2.1 eV) from GGA-PBE (PBE0 hybrid functional) calculations which can be effectively engineered by employing external biaxial compressive and tensile strain. Furthermore, the optical characteristics calculation indicates that the predicted monolayer has considerable optical absorption and reflectivity in the ultraviolet region. The results suggest that a Sb2Si monolayer has very good potential applications in new nano-optoelectronic devices.

Effects of biaxial strains on electronic and elastic properties of hexagonal XSi2 (X = Cr, Mo, W) from first-principles

NASA Astrophysics Data System (ADS)

Zhu, Haiyan; Shi, Liwei; Li, Shuaiqi; Zhang, Shaobo; Xia, Wangsuo

2018-02-01

Structural, electronic properties and elastic anisotropy of hexagonal C40 XSi2 (X = Cr, Mo, W) under equibiaxial in-plane strains are systematically studied using first-principle calculations. The energy gaps show significant changes with biaxial strains, whereas they are always indirect band-gap materials for -6% <ɛxx < 6%. All elastic constants, bulk modulus, shear modulus, Young's modulus increase (decrease) almost linearly with increasing compressive (tensile) strains. The evolutions of BH /GH ratio and Poisson's ratio indicate that these compounds have a better (worse) ductile behaviour under compressive (tensile) strains. A set of 3D plots show a larger directional variability in the Young's modulus E and shear modulus G at different strains for the three compounds, which is consist with the values of anisotropy factors. Moreover, the evolution of Debye temperature and anisotropy of sound velocities with biaxial strains are discussed.

Structural and electronic properties of CdSe/ZnS and ZnS/CdSe core/shell nanowires via first principles study

NASA Astrophysics Data System (ADS)

Rehman, Shafiq Ur; Li, H. M.; Ding, Z. J.

2018-05-01

First principles calculations have been performed to predict the structural stability and electronic structures of hydrogen passivated wurtzite CdSe/ZnS and ZnS/CdSe core/shell nanowires (CSNWs) in the [0001] direction. The calculated binding energy shows that ZnS/CdSe CSNWs are more stable than CdSe/ZnS CSNWs and the stability of ZnS/CdSe CSNWs increases with increasing the thickness of ZnS shell. The modulated electronic band gap demonstrates an increase when the size of both CSNWs is reduced, as a result of the quantum confinement effect. The core-to-shell chemical composition of atoms shows that a strong composition effect also exists in these CSNWs, which in turn affects their electronic properties. Our simulated results show that the photoemission spectra of the CSNWs can be significantly improved by tuning the energy gap of CSNWs.

The structural and electronic properties of amorphous HgCdTe from first-principles calculations

NASA Astrophysics Data System (ADS)

Zhao, Huxian; Chen, Xiaoshuang; Lu, Jianping; Shu, Haibo; Lu, Wei

2014-01-01

Amorphous mercury cadmium telluride (a-MCT) model structures, with x being 0.125 and 0.25, are obtained from first-principles calculations. We generate initial structures by computation alchemy method. It is found that most atoms in the network of amorphous structures tend to be fourfold and form tetrahedral structures, implying that the chemical ordered continuous random network with some coordination defects is the ideal structure for a-MCT. The electronic structure is also concerned. The gap is found to be 0.30 and 0.26 eV for a-Hg0.875Cd0.125Te and a-Hg0.75Cd0.25Te model structures, independent of the composition. By comparing with the properties of crystalline MCT with the same composition, we observe a blue-shift of energy band gap. The localization of tail states and its atomic origin are also discussed.

Analysis of STM images with pure and CO-functionalized tips: A first-principles and experimental study

NASA Astrophysics Data System (ADS)

Gustafsson, Alexander; Okabayashi, Norio; Peronio, Angelo; Giessibl, Franz J.; Paulsson, Magnus

2017-08-01

We describe a first-principles method to calculate scanning tunneling microscopy (STM) images, and compare the results to well-characterized experiments combining STM with atomic force microscopy (AFM). The theory is based on density functional theory with a localized basis set, where the wave functions in the vacuum gap are computed by propagating the localized-basis wave functions into the gap using a real-space grid. Constant-height STM images are computed using Bardeen's approximation method, including averaging over the reciprocal space. We consider copper adatoms and single CO molecules adsorbed on Cu(111), scanned with a single-atom copper tip with and without CO functionalization. The calculated images agree with state-of-the-art experiments, where the atomic structure of the tip apex is determined by AFM. The comparison further allows for detailed interpretation of the STM images.

First-principles study of nitrogen-doped CuAlO2

NASA Astrophysics Data System (ADS)

Xu, Ying; Ao, Zhi Min; Yuan, Ding Wang

2012-08-01

The electronic structure and formation energies of N-doped CuAlO2 are studied using first-principles calculations. It is found that, when a N atom is doped into CuAlO2, the N atom prefers to substitute an O atom rather than to occupy an interstitial site of the Cu layer. The NO acts as a shallow accepter while the Ni acts as a deep accepter. The results of the electronic structure show that the N-doping doesn't alter the band gap of CuAlO2 for the both cases. In the substitutional case, the N impurity states occur at the top of valance band maximum (VBM), which provides holes and increases the p-type conductivity. However, in the interstitial case, the N impurity states occur in the middle of the band gap, which are more localized and this indicates that it is not good for p-type conductivity.

First-principles study of intrinsic defects in formamidinium lead triiodide perovskite solar cell absorbers.

PubMed

Liu, Na; Yam, ChiYung

2018-03-07

As an alternative to methylammonium lead triiodide (MAPbI 3 ), formamidinium lead triiodide (FAPbI 3 ) perovskites have recently attracted significant attention because of their higher stability and smaller band gaps. Here, based on first-principles calculations, we investigate systematically the intrinsic defects in FAPbI 3 . While methylammonium (MA)-related defects MA I and I MA in MAPbI 3 have high formation energies, we found that formamidinium (FA)-related defects V FA , FA I and I FA in FAPbI 3 have much lower formation energies. Antisites FA I and I FA create deep levels in the band gap, and they can act as recombination centers and result in reduced carrier lifetimes and low open circuit voltages in FAPbI 3 -based photovoltaic devices. We further demonstrate that through cation mixing of MA and FA in perovskites the formation of these defects can be substantially suppressed.

First-principles study on the magnetic and electronic properties of Al or P doped armchair silicene nanoribbons

NASA Astrophysics Data System (ADS)

Zhang, Xiaojiao; Zhang, Dan; Xie, Fang; Zheng, Xialian; Wang, Haiyan; Long, Mengqiu

2017-07-01

Using the first-principles calculations, we investigate the geometric structure, electronic and magnetic properties of armchair silicene nanoribbons (ASiNRs) doped with aluminum (Al) or phosphorus (P) atoms. Total energy analysis shows that both Al and P atoms are preferentially doping at the edge site of ASiNRs. And the magnetism can be found in both Al and P doped systems. For Al doped ASiNRs, we find that the magnetic moment and band gap are dependent on the ribbon width. While for P doped ASiNRs, the magnetic moment always keeps 1μB and is independent of the ribbon width, meanwhile the band gap oscillates with a period of three with the ribbon width increasing. Our results present a new avenue for band engineering of SiNRs and benefit for the designing of silicone-based nano-spin-devices in nanoelectronics.

First-principles prediction of new photocatalyst materials with visible-light absorption and improved charge separation: surface modification of rutile TiO₂ with nanoclusters of MgO and Ga₂O₃.

PubMed

Nolan, Michael

2012-11-01

Titanium dioxide is an important and widely studied photocatalytic material, but to achieve photocatalytic activity under visible-light absorption, it needs to have a narrower band gap and reduced charge carrier recombination. First-principles simulations are presented in this paper to show that heterostructures of rutil TiO₂ modified with nanoclusters of MgO and Ga₂O₃ will be new photocatalytically active materials in the UV (MgO-TiO₂) and visible (Ga₂O₃-TiO₂) regions of the solar spectrum. In particular, our investigations of a model of the excited state of the heterostructures demonstrate that upon light excitation electrons and holes can be separated onto the TiO₂ surface and the metal oxide nanocluster, which will reduce charge recombination and improve photocatalytic activity. For MgO-modified TiO₂, no significant band gap change is predicted, but for Ga₂O₃-modified TiO₂ we predict a band gap change of up to 0.6 eV, which is sufficient to induce visible light absorption. Comparisons with unmodified TiO₂ and other TiO₂-based photocatalyst structures are presented.

First-principles study of structural, electronic, and optical properties of surface defects in GaAs(001) - β2(2x4)

NASA Astrophysics Data System (ADS)

Bacuyag, Dhonny; Escaño, Mary Clare Sison; David, Melanie; Tani, Masahiko

2018-06-01

We performed first-principles calculations based on density functional theory (DFT) to investigate the role of point defects in the structural, electronic, and optical properties of the GaAs(001)- β2(2x4). In terms of structural properties, AsGa is the most stable defect structure, consistent with experiments. With respect to the electronic structure, band structures revealed the existence of sub-band and midgap states for all defects. The induced sub-bands and midgap states originated from the redistributions of charges towards these defects and neighboring atoms. The presence of these point defects introduced deep energy levels characteristic of EB3 (0.97 eV), EL4 (0.52 eV), and EL2 (0.82 eV) for AsGa, GaAs, GaV, respectively. The optical properties are found to be strongly related to these induced gap states. The calculated onset values in the absorption spectra, corresponding to the energy gaps, confirmed the absorption below the known bulk band gap of 1.43 eV. These support the possible two-step photoabsorption mediated by midgap states as observed in experiments.

Temperature Dependence of the Energy Levels of Methylammonium Lead Iodide Perovskite from First-Principles.

PubMed

Saidi, Wissam A; Poncé, Samuel; Monserrat, Bartomeu

2016-12-15

Environmental effects and intrinsic energy-loss processes lead to fluctuations in the operational temperature of solar cells, which can profoundly influence their power conversion efficiency. Here we determine from first-principles the effects of temperature on the band gap and band edges of the hybrid pervoskite CH 3 NH 3 PbI 3 by accounting for electron-phonon coupling and thermal expansion. From 290 to 380 K, the computed band gap change of 40 meV coincides with the experimental change of 30-40 meV. The calculation of electron-phonon coupling in CH 3 NH 3 PbI 3 is particularly intricate as the commonly used Allen-Heine-Cardona theory overestimates the band gap change with temperature, and excellent agreement with experiment is only obtained when including high-order terms in the electron-phonon interaction. We also find that spin-orbit coupling enhances the electron-phonon coupling strength but that the inclusion of nonlocal correlations using hybrid functionals has little effect. We reach similar conclusions in the metal-halide perovskite CsPbI 3 . Our results unambiguously confirm for the first time the importance of high-order terms in the electron-phonon coupling by direct comparison with experiment.

Gap-state engineering of visible-light-active ferroelectrics for photovoltaic applications.

PubMed

Matsuo, Hiroki; Noguchi, Yuji; Miyayama, Masaru

2017-08-08

Photoferroelectrics offer unique opportunities to explore light energy conversion based on their polarization-driven carrier separation and above-bandgap voltages. The problem associated with the wide bandgap of ferroelectric oxides, i.e., the vanishingly small photoresponse under visible light, has been overcome partly by bandgap tuning, but the narrowing of the bandgap is, in principle, accompanied by a substantial loss of ferroelectric polarization. In this article, we report an approach, 'gap-state' engineering, to produce photoferroelectrics, in which defect states within the bandgap act as a scaffold for photogeneration. Our first-principles calculations and single-domain thin-film experiments of BiFeO 3 demonstrate that gap states half-filled with electrons can enhance not only photocurrents but also photovoltages over a broad photon-energy range that is different from intermediate bands in present semiconductor-based solar cells. Our approach opens a promising route to the material design of visible-light-active ferroelectrics without sacrificing spontaneous polarization.Overcoming the optical transparency of wide bandgap of ferroelectric oxides by narrowing its bandgap tends to result in a loss of polarization. By utilizing defect states within the bandgap, Matsuo et al. report visible-light-active ferroelectrics without sacrificing polarization.

First-principles studies of electron transport in Ga2O3

NASA Astrophysics Data System (ADS)

Kang, Youngho; Krishnaswamy, Karthik; Peelaers, Hartwin; van de Walle, Chris G.

Ga2O3 is a wide-gap semiconductor with a monoclinic crystal structure and a band gap of 4.8 eV. Its high carrier mobility and large band gap have attracted a lot of attention for use in high power electronics and transparent conductors. Despite its potential for adoption in these applications, an understanding of its carrier transport properties is still lacking. In this study we use first-principles calculations to analyze and compute the electron scattering rates in Ga2O3. Scattering due to ionized impurities and polar longitudinal-optical (LO) phonon is taken into account. We find that the electron mobility is nearly isotropic, despite the low-symmetry monoclinic structure of Ga2O3. At low carrier densities ( 1017 cm-3), the mobility is limited by LO phonon scattering. Scattering by ionized impurities becomes increasingly important at higher carrier densities. This type of scattering is enhanced when compensating native point defects are present; in particular, gallium vacancies, which are triply negatively charged, can have a strong effect on mobility. These effects explain the downturn in mobility observed in experiments at high carrier densities. This work was supported by ARO and NSF.

Prospective guidance in a free-swimming cell.

PubMed

Delafield-Butt, Jonathan T; Pepping, Gert-Jan; McCaig, Colin D; Lee, David N

2012-07-01

A systems theory of movement control in animals is presented in this article and applied to explaining the controlled behaviour of the single-celled Paramecium caudatum in an electric field. The theory-General Tau Theory-is founded on three basic principles: (i) all purposive movement entails prospectively controlling the closure of action-gaps (e.g. a distance gap when reaching, or an angle gap when steering); (ii) the sole informational variable required for controlling gaps is the relative rate of change of the gap (the time derivative of the gap size divided by the size), which can be directly sensed; and (iii) a coordinated movement is achieved by keeping the relative rates of change of gaps in a constant ratio. The theory is supported by studies of controlled movement in mammals, birds and insects. We now show for the first time that it is also supported by single-celled paramecia steering to the cathode in a bi-polar electric field. General Tau Theory is deployed to explain this guided steering by the cell. This article presents the first computational model of prospective perceptual control in a non-neural, single-celled system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyra, Wladimir; Lin, Min-Kai, E-mail: wlyra@caltech.edu, E-mail: mklin924@cita.utoronto.ca

The Atacama Large Millimeter Array has returned images of transitional disks in which large asymmetries are seen in the distribution of millimeter sized dust in the outer disk. The explanation in vogue borrows from the vortex literature and suggests that these asymmetries are the result of dust trapping in giant vortices, excited via Rossby wave instabilities at planetary gap edges. Due to the drag force, dust trapped in vortices will accumulate in the center and diffusion is needed to maintain a steady state over the lifetime of the disk. While previous work derived semi-analytical models of the process, in thismore » paper we provide analytical steady-steady solutions. Exact solutions exist for certain vortex models. The solution is determined by the vortex rotation profile, the gas scale height, the vortex aspect ratio, and the ratio of dust diffusion to gas-dust friction. In principle, all of these quantities can be derived from observations, which would validate the model and also provide constrains on the strength of the turbulence inside the vortex core. Based on our solution, we derive quantities such as the gas-dust contrast, the trapped dust mass, and the dust contrast at the same orbital location. We apply our model to the recently imaged Oph IRS 48 system, finding values within the range of the observational uncertainties.« less

Knowing one's place: a free-energy approach to pattern regulation

PubMed Central

Friston, Karl; Levin, Michael; Sengupta, Biswa; Pezzulo, Giovanni

2015-01-01

Understanding how organisms establish their form during embryogenesis and regeneration represents a major knowledge gap in biological pattern formation. It has been recently suggested that morphogenesis could be understood in terms of cellular information processing and the ability of cell groups to model shape. Here, we offer a proof of principle that self-assembly is an emergent property of cells that share a common (genetic and epigenetic) model of organismal form. This behaviour is formulated in terms of variational free-energy minimization—of the sort that has been used to explain action and perception in neuroscience. In brief, casting the minimization of thermodynamic free energy in terms of variational free energy allows one to interpret (the dynamics of) a system as inferring the causes of its inputs—and acting to resolve uncertainty about those causes. This novel perspective on the coordination of migration and differentiation of cells suggests an interpretation of genetic codes as parametrizing a generative model—predicting the signals sensed by cells in the target morphology—and epigenetic processes as the subsequent inversion of that model. This theoretical formulation may complement bottom-up strategies—that currently focus on molecular pathways—with (constructivist) top-down approaches that have proved themselves in neuroscience and cybernetics. PMID:25788538

Exploration of quantum-memory-assisted entropic uncertainty relations in a noninertial frame

NASA Astrophysics Data System (ADS)

Wang, Dong; Ming, Fei; Huang, Ai-Jun; Sun, Wen-Yang; Shi, Jia-Dong; Ye, Liu

2017-05-01

The uncertainty principle offers a bound to show accuracy of the simultaneous measurement outcome for two incompatible observables. In this letter, we investigate quantum-memory-assisted entropic uncertainty relation (QMA-EUR) when the particle to be measured stays at an open system, and another particle is treated as quantum memory under a noninertial frame. In such a scenario, the collective influence of the unital and nonunital noise environment, and of the relativistic motion of the system, on the QMA-EUR is examined. By numerical analysis, we conclude that, firstly, the noises and the Unruh effect can both increase the uncertainty, due to the decoherence of the bipartite system induced by the noise or Unruh effect; secondly, the uncertainty is more affected by the noises than by the Unruh effect from the acceleration; thirdly, unital noises can reduce the uncertainty in long-time regime. We give a possible physical interpretation for those results: that the information of interest is redistributed among the bipartite, the noisy environment and the physically inaccessible region in the noninertial frame. Therefore, we claim that our observations provide an insight into dynamics of the entropic uncertainty in a noninertial frame, and might be important to quantum precision measurement under relativistic motion.

Shape and edge dependent electronic and magnetic properties of silicene nano-flakes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohan, Brij, E-mail: brijmohanhpu@yahoo.com; Pooja,; Ahluwalia, P. K.

2015-06-24

We performed first-principle study of the geometric, electronic and magnetic properties of arm-chair and zigzag edge silicene nano-flakes of triangular and hexagonal shapes. Electronic properties of silicene nano-flakes show strong dependence on their edge structure and shape. The considered nanostructures shows energy gap ranging ∼ 0.4 – 1.0 eV. Zigzag edged triangular nano-flake is magnetic and semiconducting in nature with 4.0 µ{sub B} magnetic moment and ∼ 0.4 eV energy gap.

The amount of ergonomics and user involvement in 151 design processes.

PubMed

Kok, Barbara N E; Slegers, Karin; Vink, Peter

2012-01-01

Ergonomics, usability and user-centered design are terms that are well known among designers. Yet, products often seem to fail to meet the users' needs, resulting in a gap between expected and experienced usability. To understand the possible causes of this gap the actions taken by the designer during the design process are studied in this paper. This can show whether and how certain actions influence the user-friendliness of the design products. The aim of this research was to understand whether ergonomic principles and methods are included in the design process, whether users are involved in this process and whether the experience of the designer (in ergonomics/user involvement) has an effect on the end product usability. In this study the design processes of 151 tangible products of students in design were analyzed. It showed that in 75% of the cases some ergonomic principles were applied. User involvement was performed in only 1/3 of the design cases. Hardly any correlation was found between the designers' experience in ergonomic principles and the way they applied it and no correlations were found between the designers' experience in user involvement and the users' involvement in the design process.

Global ethics and principlism.

PubMed

Gordon, John-Stewart

2011-09-01

This article examines the special relation between common morality and particular moralities in the four-principles approach and its use for global ethics. It is argued that the special dialectical relation between common morality and particular moralities is the key to bridging the gap between ethical universalism and relativism. The four-principles approach is a good model for a global bioethics by virtue of its ability to mediate successfully between universal demands and cultural diversity. The principle of autonomy (i.e., the idea of individual informed consent), however, does need to be revised so as to make it compatible with alternatives such as family- or community-informed consent. The upshot is that the contribution of the four-principles approach to global ethics lies in the so-called dialectical process and its power to deal with cross-cultural issues against the background of universal demands by joining them together.

Simulation's Ensemble is Better Than Ensemble Simulation

NASA Astrophysics Data System (ADS)

Yan, X.

2017-12-01

Simulation's ensemble is better than ensemble simulation Yan Xiaodong State Key Laboratory of Earth Surface Processes and Resource Ecology (ESPRE) Beijing Normal University,19 Xinjiekouwai Street, Haidian District, Beijing 100875, China Email: yxd@bnu.edu.cnDynamical system is simulated from initial state. However initial state data is of great uncertainty, which leads to uncertainty of simulation. Therefore, multiple possible initial states based simulation has been used widely in atmospheric science, which has indeed been proved to be able to lower the uncertainty, that was named simulation's ensemble because multiple simulation results would be fused . In ecological field, individual based model simulation (forest gap models for example) can be regarded as simulation's ensemble compared with community based simulation (most ecosystem models). In this talk, we will address the advantage of individual based simulation and even their ensembles.

Application of fuzzy system theory in addressing the presence of uncertainties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yusmye, A. Y. N.; Goh, B. Y.; Adnan, N. F.

In this paper, the combinations of fuzzy system theory with the finite element methods are present and discuss to deal with the uncertainties. The present of uncertainties is needed to avoid for prevent the failure of the material in engineering. There are three types of uncertainties, which are stochastic, epistemic and error uncertainties. In this paper, the epistemic uncertainties have been considered. For the epistemic uncertainty, it exists as a result of incomplete information and lack of knowledge or data. Fuzzy system theory is a non-probabilistic method, and this method is most appropriate to interpret the uncertainty compared to statisticalmore » approach when the deal with the lack of data. Fuzzy system theory contains a number of processes started from converting the crisp input to fuzzy input through fuzzification process and followed by the main process known as mapping process. The term mapping here means that the logical relationship between two or more entities. In this study, the fuzzy inputs are numerically integrated based on extension principle method. In the final stage, the defuzzification process is implemented. Defuzzification is an important process to allow the conversion of the fuzzy output to crisp outputs. Several illustrative examples are given and from the simulation, the result showed that propose the method produces more conservative results comparing with the conventional finite element method.« less

To be or not to be: How do we speak about uncertainty in public?

NASA Astrophysics Data System (ADS)

Todesco, Micol; Lolli, Barbara; Sheldrake, Tom; Odbert, Henry

2016-04-01

One of the challenges related to hazard communication concerns the public perception and understanding of scientific uncertainties, and of its implications in terms of hazard assessment and mitigation. Often science is perceived as an effective dispenser of resolving answers to the main issues posed by the complexities of life and nature. In this perspective, uncertainty is seen as a pernicious lack of knowledge that hinders our ability to face complex problems. From a scientific perspective, however, the definition of uncertainty is the only valuable tool we have to handle errors affecting our data and propagating through the increasingly complex models we develop to describe reality. Through uncertainty, scientists acknowledge the great variability that characterises natural systems and account for it in their assessment of possible scenarios. From this point of view, uncertainty is not ignorance, but it rather provides a great deal of information that is needed to inform decision making. To find effective ways to bridge the gap between these different meaning of uncertainty, we asked high-school students for assistance. With their help, we gathered definitions of the term 'uncertainty' interviewing different categories of peoples, including schoolmates and professors, neighbours, families and friends. These definitions will be compared with those provided by scientists, to find differences and similarity. To understand the role of uncertainty on judgment, a hands-on experiment is performed where students will have to estimate the exact time of explosion of party poppers subjected to a variable degree of pull. At the end of the project, the students will express their own understanding of uncertainty in a video, which will be made available for sharing. Materials collected during all the activities will contribute to our understanding of how uncertainty is portrayed and can be better expressed to improve our hazard communication.

Some applications of the most general form of the higher-order GUP with minimal length uncertainty and maximal momentum

NASA Astrophysics Data System (ADS)

Shababi, Homa; Chung, Won Sang

2018-04-01

In this paper, using the new type of D-dimensional nonperturbative Generalized Uncertainty Principle (GUP) which has predicted both a minimal length uncertainty and a maximal observable momentum,1 first, we obtain the maximally localized states and express their connections to [P. Pedram, Phys. Lett. B 714, 317 (2012)]. Then, in the context of our proposed GUP and using the generalized Schrödinger equation, we solve some important problems including particle in a box and one-dimensional hydrogen atom. Next, implying modified Bohr-Sommerfeld quantization, we obtain energy spectra of quantum harmonic oscillator and quantum bouncer. Finally, as an example, we investigate some statistical properties of a free particle, including partition function and internal energy, in the presence of the mentioned GUP.

Scaling Up Decision Theoretic Planning to Planetary Rover Problems

NASA Technical Reports Server (NTRS)

Meuleau, Nicolas; Dearden, Richard; Washington, Rich

2004-01-01

Because of communication limits, planetary rovers must operate autonomously during consequent durations. The ability to plan under uncertainty is one of the main components of autonomy. Previous approaches to planning under uncertainty in NASA applications are not able to address the challenges of future missions, because of several apparent limits. On another side, decision theory provides a solid principle framework for reasoning about uncertainty and rewards. Unfortunately, there are several obstacles to a direct application of decision-theoretic techniques to the rover domain. This paper focuses on the issues of structure and concurrency, and continuous state variables. We describes two techniques currently under development that address specifically these issues and allow scaling-up decision theoretic solution techniques to planetary rover planning problems involving a small number of goals.

Reply to "Comment on 'Fractional quantum mechanics' and 'Fractional Schrödinger equation' ".

PubMed

Laskin, Nick

2016-06-01

The fractional uncertainty relation is a mathematical formulation of Heisenberg's uncertainty principle in the framework of fractional quantum mechanics. Two mistaken statements presented in the Comment have been revealed. The origin of each mistaken statement has been clarified and corrected statements have been made. A map between standard quantum mechanics and fractional quantum mechanics has been presented to emphasize the features of fractional quantum mechanics and to avoid misinterpretations of the fractional uncertainty relation. It has been shown that the fractional probability current equation is correct in the area of its applicability. Further studies have to be done to find meaningful quantum physics problems with involvement of the fractional probability current density vector and the extra term emerging in the framework of fractional quantum mechanics.

Band Gap Engineering of Titania Systems Purposed for Photocatalytic Activity

NASA Astrophysics Data System (ADS)

Thurston, Cameron

Ab initio computer aided design drastically increases candidate population for highly specified material discovery and selection. These simulations, carried out through a first-principles computational approach, accurately extrapolate material properties and behavior. Titanium Dioxide (TiO2 ) is one such material that stands to gain a great deal from the use of these simulations. In its anatase form, titania (TiO2 ) has been found to exhibit a band gap nearing 3.2 eV. If titania is to become a viable alternative to other contemporary photoactive materials exhibiting band gaps better suited for the solar spectrum, then the band gap must be subsequently reduced. To lower the energy needed for electronic excitation, both transition metals and non-metals have been extensively researched and are currently viable candidates for the continued reduction of titania's band gap. The introduction of multicomponent atomic doping introduces new energy bands which tend to both reduce the band gap and recombination loss. Ta-N, Nb-N, V-N, Cr-N, Mo-N, and W-N substitutions were studied in titania and subsequent energy and band gap calculations show a favorable band gap reduction in the case of passivated systems.

Response to Burgman and Regan: the elephant in the rhetoric on info-gap decision theory.

PubMed

Sniedovich, Moshe

2014-01-01

The formal, rigorous assessment of IGDT in Sniedovich (2012) reveals that this theory's central pillar, namely its robustness model, is a reinvention of a well-established model of local robustness, known universally as radius of stability (circa 1960). As a matter of fact, this robustness model is a simple model derived from Wald's famous maximin paradigm (circa 1940). This means that had there been any gap in the state of the art that IGDT could have possibly presumed to fill, this gap had already been filled decades ago, well before IGDT was even contemplated. The conclusion therefore is that there is no gap in the state of the art that IGDT does fill, or can possibly fill, or is called upon to fill. Also, since IGDT is based on a definition of local robustness, the theory is unsuitable for the treatment of a severe uncertainty of the type that this theory claims to address. Therefore, since the theory claims to be particularly suitable for the treatment of a severe, unbounded uncertainty, the inevitable conclusion is that this theory constitutes a voodoo decision theory par excellence. Fig. 1 speaks for itself so that no amount of rhetoric can explain this fact away. The Letter's attempt to brush off valid, rigorous, well-documented criticism of IGDT as "... haggling over terminology ..." is yet another attempt to avoid dealing with the elephant in the IGDT room. Nothing will be gained from the use of misleading rhetorics to argue that ideas, models, techniques, approaches, etc., that go back to the 1940s and 1960s, are IGDT innovations. But more than this, what good can come of misapplications of these ideas in applied ecology and conservation biology? In the Appendix, I address a more intriguing question, namely: QUESTION 2: What could possibly be the rationale that motivated a search for a (nonexistent) gap in the state of the art for IGDT to fill?

The Introduction of Agility into Albania.

ERIC Educational Resources Information Center

Smith-Stevens, Eileen J.; Shkurti, Drita

1998-01-01

Describes a plan to introduce and achieve a national awareness of agility (and easy entry into the world market) for Albania through the relatively stable higher-education order. Agility's four strategic principles are enriching the customer, cooperating to enhance competitiveness, organizing to master change and uncertainty, and leveraging the…

Trends in Modern War Gaming: The Art of Conversation

DTIC Science & Technology

2014-01-01

overtook, and in some cases replaced, these thought processes. as Jung aptly noted, “in the West, consciousness has been developed mainly through...Werner Heisenberg’s uncertainty principle in 1927, successive generations of quantum theorists have moved well beyond anecdotal claims into the realm of

Reproducing Southern Hardwoods is Easier Than You Think

Treesearch

R. L. Johnson; R. C. Biesterfeldt

1971-01-01

Throughout the South poor upland hardwood stands are being converted to pine, while bottom-land hardwood stands are largely ignored. Why are Southern foresters preoccupied with pines? Uncertainties about hardwood markets and gaps in available information about hardwood management are contributing causes, but fear is probably a key factor. Foresters much prefer the well...

Preparing Students for Front-Line Management: Non-Routine Day-to-Day Decisions

ERIC Educational Resources Information Center

Clydesdale, Greg; Tan, John

2009-01-01

Purpose: This paper attempts to reduce the gap between management education and practice. It emphasises day-to-day decisions that middle and lower level managers make. The purpose is to provide an education framework embodying a flexible approach to interpretation and solution creation, suitable for situations of ambiguity and uncertainty.…

Falling through the Gaps: Safeguarding Children Trafficked into the UK

ERIC Educational Resources Information Center

Bokhari, Farrah

2008-01-01

An overview of child trafficking in the UK explores the nature and methods of this abuse, as well as the treatment and protection afforded to these particularly vulnerable children. It highlights the shortcomings and inconsistent standards of local authorities, the lack of specialist protection and the uncertainty of a trafficked child's…

Application Development Methodology Appropriateness: An Exploratory Case Study Bridging the Gap between Framework Characteristics and Selection

ERIC Educational Resources Information Center

Williams, Lawrence H., Jr.

2013-01-01

This qualitative study analyzed experiences of twenty software developers. The research showed that all software development methodologies are distinct from each other. While some, such as waterfall, focus on traditional, plan-driven approaches that allow software requirements and design to evolve; others facilitate ambiguity and uncertainty by…

Anger, Fear, Uncertainty, and Attitudes: A Test of the Cognitive-Functional Model.

ERIC Educational Resources Information Center

Nabi, Robin L.

2002-01-01

Explains that the cognitive-functional model of discrete negative emotions and attitude change attempts to bridge the theoretical gap between "emotional" and "rational" approaches to persuasion by focusing on how emotions motivate attention to and processing of persuasive messages. Explores the effects two emotions, anger and fear, and two levels…

Elastic and inelastic neutron scattering cross sections for fission reactor applications

NASA Astrophysics Data System (ADS)

Hicks, S. F.; Chakraborty, A.; Combs, B.; Crider, B. P.; Downes, L.; Girgis, J.; Kersting, L. J.; Kumar, A.; Lueck, C. J.; McDonough, P. J.; McEllistrem, M. T.; Peters, E. E.; Prados-Estevz, F. M.; Schniederjan, J.; Sidwell, L.; Sigillito, A. J.; Vanhoy, J. R.; Watts, D.; Yates, S. W.

2013-04-01

Nuclear data important for the design and development of the next generation of light-water reactors and future fast reactors include neutron elastic and inelastic scattering cross sections on important structural materials, such as Fe, and on coolant materials, such as Na. These reaction probabilities are needed since neutron reactions impact fuel performance during irradiations and the overall efficiency of reactors. While neutron scattering cross sections from these materials are available for certain incident neutron energies, the fast neutron region, particularly above 2 MeV, has large gaps for which no measurements exist, or the existing uncertainties are large. Measurements have been made at the University of Kentucky Accelerator Laboratory to measure neutron scattering cross sections on both Fe and Na in the region where these gaps occur and to reduce the uncertainties on scattering from the ground state and first excited state of these nuclei. Results from measurements on Fe at incident neutron energies between 2 and 4 MeV will be presented and comparisons will be made to model calculations available from data evaluators.

A Hot-Deck Multiple Imputation Procedure for Gaps in Longitudinal Recurrent Event Histories

PubMed Central

Wang, Chia-Ning; Little, Roderick; Nan, Bin; Harlow, Siobán D.

2012-01-01

Summary We propose a regression-based hot deck multiple imputation method for gaps of missing data in longitudinal studies, where subjects experience a recurrent event process and a terminal event. Examples are repeated asthma episodes and death, or menstrual periods and the menopause, as in our motivating application. Research interest concerns the onset time of a marker event, defined by the recurrent-event process, or the duration from this marker event to the final event. Gaps in the recorded event history make it difficult to determine the onset time of the marker event, and hence, the duration from onset to the final event. Simple approaches such as jumping gap times or dropping cases with gaps have obvious limitations. We propose a procedure for imputing information in the gaps by substituting information in the gap from a matched individual with a completely recorded history in the corresponding interval. Predictive Mean Matching is used to incorporate information on longitudinal characteristics of the repeated process and the final event time. Multiple imputation is used to propagate imputation uncertainty. The procedure is applied to an important data set for assessing the timing and duration of the menopausal transition. The performance of the proposed method is assessed by a simulation study. PMID:21361886

First principles study of CuAlO2 doping with S

NASA Astrophysics Data System (ADS)

Gao, Haigen; Zhou, Jian; Lu, Minghui

2010-07-01

We study the electronic properties of CuAlO2 doped with S by the first principles calculations and find that the band gap of CuAlO2 is reduced after the doping. At the same time, the effective masses are also reduced and the density of states could cross the Fermi level. These results show that the conductivity of CuAlO2 could be enhanced by doping the impurities of S, which needs to be further studied.

Band structures of TiO2 doped with N, C and B*

PubMed Central

Xu, Tian-Hua; Song, Chen-Lu; Liu, Yong; Han, Gao-Rong

2006-01-01

This study on the band structures and charge densities of nitrogen (N)-, carbon (C)- and boron (B)-doped titanium dioxide (TiO2) by first-principles simulation with the CASTEP code (Segall et al., 2002) showed that the three 2p bands of impurity atom are located above the valence-band maximum and below the Ti 3d bands, and that along with the decreasing of impurity atomic number, the fluctuations become more intensive. We cannot observe obvious band-gap narrowing in our result. Therefore, the cause of absorption in visible light might be the isolated impurity atom 2p states in band-gap rather than the band-gap narrowing. PMID:16532532

Entropic uncertainty relations in the Heisenberg XXZ model and its controlling via filtering operations

NASA Astrophysics Data System (ADS)

Ming, Fei; Wang, Dong; Shi, Wei-Nan; Huang, Ai-Jun; Sun, Wen-Yang; Ye, Liu

2018-04-01

The uncertainty principle is recognized as an elementary ingredient of quantum theory and sets up a significant bound to predict outcome of measurement for a couple of incompatible observables. In this work, we develop dynamical features of quantum memory-assisted entropic uncertainty relations (QMA-EUR) in a two-qubit Heisenberg XXZ spin chain with an inhomogeneous magnetic field. We specifically derive the dynamical evolutions of the entropic uncertainty with respect to the measurement in the Heisenberg XXZ model when spin A is initially correlated with quantum memory B. It has been found that the larger coupling strength J of the ferromagnetism ( J < 0 ) and the anti-ferromagnetism ( J > 0 ) chains can effectively degrade the measuring uncertainty. Besides, it turns out that the higher temperature can induce the inflation of the uncertainty because the thermal entanglement becomes relatively weak in this scenario, and there exists a distinct dynamical behavior of the uncertainty when an inhomogeneous magnetic field emerges. With the growing magnetic field | B | , the variation of the entropic uncertainty will be non-monotonic. Meanwhile, we compare several different optimized bounds existing with the initial bound proposed by Berta et al. and consequently conclude Adabi et al.'s result is optimal. Moreover, we also investigate the mixedness of the system of interest, dramatically associated with the uncertainty. Remarkably, we put forward a possible physical interpretation to explain the evolutionary phenomenon of the uncertainty. Finally, we take advantage of a local filtering operation to steer the magnitude of the uncertainty. Therefore, our explorations may shed light on the entropic uncertainty under the Heisenberg XXZ model and hence be of importance to quantum precision measurement over solid state-based quantum information processing.

MICROSCOPE Mission: First Results of a Space Test of the Equivalence Principle.

PubMed

Touboul, Pierre; Métris, Gilles; Rodrigues, Manuel; André, Yves; Baghi, Quentin; Bergé, Joël; Boulanger, Damien; Bremer, Stefanie; Carle, Patrice; Chhun, Ratana; Christophe, Bruno; Cipolla, Valerio; Damour, Thibault; Danto, Pascale; Dittus, Hansjoerg; Fayet, Pierre; Foulon, Bernard; Gageant, Claude; Guidotti, Pierre-Yves; Hagedorn, Daniel; Hardy, Emilie; Huynh, Phuong-Anh; Inchauspe, Henri; Kayser, Patrick; Lala, Stéphanie; Lämmerzahl, Claus; Lebat, Vincent; Leseur, Pierre; Liorzou, Françoise; List, Meike; Löffler, Frank; Panet, Isabelle; Pouilloux, Benjamin; Prieur, Pascal; Rebray, Alexandre; Reynaud, Serge; Rievers, Benny; Robert, Alain; Selig, Hanns; Serron, Laura; Sumner, Timothy; Tanguy, Nicolas; Visser, Pieter

2017-12-08

According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10^{-15} precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force. Analysis of the first data gives δ(Ti,Pt)=[-1±9(stat)±9(syst)]×10^{-15} (1σ statistical uncertainty) for the titanium-platinum Eötvös parameter characterizing the relative difference in their free-fall accelerations.

MICROSCOPE Mission: First Results of a Space Test of the Equivalence Principle

NASA Astrophysics Data System (ADS)

Touboul, Pierre; Métris, Gilles; Rodrigues, Manuel; André, Yves; Baghi, Quentin; Bergé, Joël; Boulanger, Damien; Bremer, Stefanie; Carle, Patrice; Chhun, Ratana; Christophe, Bruno; Cipolla, Valerio; Damour, Thibault; Danto, Pascale; Dittus, Hansjoerg; Fayet, Pierre; Foulon, Bernard; Gageant, Claude; Guidotti, Pierre-Yves; Hagedorn, Daniel; Hardy, Emilie; Huynh, Phuong-Anh; Inchauspe, Henri; Kayser, Patrick; Lala, Stéphanie; Lämmerzahl, Claus; Lebat, Vincent; Leseur, Pierre; Liorzou, Françoise; List, Meike; Löffler, Frank; Panet, Isabelle; Pouilloux, Benjamin; Prieur, Pascal; Rebray, Alexandre; Reynaud, Serge; Rievers, Benny; Robert, Alain; Selig, Hanns; Serron, Laura; Sumner, Timothy; Tanguy, Nicolas; Visser, Pieter

2017-12-01

According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10-15 precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force. Analysis of the first data gives δ (Ti ,Pt )=[-1 ±9 (stat)±9 (syst)]×10-15 (1 σ statistical uncertainty) for the titanium-platinum Eötvös parameter characterizing the relative difference in their free-fall accelerations.

How measurement science can improve confidence in research results.

PubMed

Plant, Anne L; Becker, Chandler A; Hanisch, Robert J; Boisvert, Ronald F; Possolo, Antonio M; Elliott, John T

2018-04-01

The current push for rigor and reproducibility is driven by a desire for confidence in research results. Here, we suggest a framework for a systematic process, based on consensus principles of measurement science, to guide researchers and reviewers in assessing, documenting, and mitigating the sources of uncertainty in a study. All study results have associated ambiguities that are not always clarified by simply establishing reproducibility. By explicitly considering sources of uncertainty, noting aspects of the experimental system that are difficult to characterize quantitatively, and proposing alternative interpretations, the researcher provides information that enhances comparability and reproducibility.

Sizable band gap in organometallic topological insulator

NASA Astrophysics Data System (ADS)

Derakhshan, V.; Ketabi, S. A.

2017-01-01

Based on first principle calculation when Ceperley-Alder and Perdew-Burke-Ernzerh type exchange-correlation energy functional were adopted to LSDA and GGA calculation, electronic properties of organometallic honeycomb lattice as a two-dimensional topological insulator was calculated. In the presence of spin-orbit interaction bulk band gap of organometallic lattice with heavy metals such as Au, Hg, Pt and Tl atoms were investigated. Our results show that the organometallic topological insulator which is made of Mercury atom shows the wide bulk band gap of about ∼120 meV. Moreover, by fitting the conduction and valence bands to the band-structure which are produced by Density Functional Theory, spin-orbit interaction parameters were extracted. Based on calculated parameters, gapless edge states within bulk insulating gap are indeed found for finite width strip of two-dimensional organometallic topological insulators.

Quantum spin Hall insulator in halogenated arsenene films with sizable energy gaps

PubMed Central

Wang, Dongchao; Chen, Li; Shi, Changmin; Wang, Xiaoli; Cui, Guangliang; Zhang, Pinhua; Chen, Yeqing

2016-01-01

Based on first-principles calculations, the electronic and topological properties of halogenated (F-, Cl-, Br- and I-) arsenene are investigated in detail. It is found that the halogenated arsenene sheets show Dirac type characteristic in the absence of spin-orbital coupling (SOC), whereas energy gap will be induced by SOC with the values ranging from 0.194 eV for F-arsenene to 0.255 eV for I-arsenene. Noticeably, these four newly proposed two-dimensional (2D) systems are verified to be quantum spin Hall (QSH) insulators by calculating the edge states with obvious linear cross inside bulk energy gap. It should be pointed out that the large energy gap in these 2D materials consisted of commonly used element is quite promising for practical applications of QSH insulators at room temperature. PMID:27340091

Principles for high-quality, high-value testing.

PubMed

Power, Michael; Fell, Greg; Wright, Michael

2013-02-01

A survey of doctors working in two large NHS hospitals identified over 120 laboratory tests, imaging investigations and investigational procedures that they considered not to be overused. A common suggestion in this survey was that more training was required. And, this prompted the development of a list of core principles for high-quality, high-value testing. The list can be used as a framework for training and as a reference source. The core principles are: (1) Base testing practices on the best available evidence. (2) Apply the evidence on test performance with careful judgement. (3) Test efficiently. (4) Consider the value (and affordability) of a test before requesting it. (5) Be aware of the downsides and drivers of overdiagnosis. (6) Confront uncertainties. (7) Be patient-centred in your approach. (8) Consider ethical issues. (9) Be aware of normal cognitive limitations and biases when testing. (10) Follow the 'knowledge journey' when teaching and learning these core principles.

Good modeling practice guidelines for applying multimedia models in chemical assessments.

PubMed

Buser, Andreas M; MacLeod, Matthew; Scheringer, Martin; Mackay, Don; Bonnell, Mark; Russell, Mark H; DePinto, Joseph V; Hungerbühler, Konrad

2012-10-01

Multimedia mass balance models of chemical fate in the environment have been used for over 3 decades in a regulatory context to assist decision making. As these models become more comprehensive, reliable, and accepted, there is a need to recognize and adopt principles of Good Modeling Practice (GMP) to ensure that multimedia models are applied with transparency and adherence to accepted scientific principles. We propose and discuss 6 principles of GMP for applying existing multimedia models in a decision-making context, namely 1) specification of the goals of the model assessment, 2) specification of the model used, 3) specification of the input data, 4) specification of the output data, 5) conduct of a sensitivity and possibly also uncertainty analysis, and finally 6) specification of the limitations and limits of applicability of the analysis. These principles are justified and discussed with a view to enhancing the transparency and quality of model-based assessments. Copyright © 2012 SETAC.

Absolute earthquake locations using 3-D versus 1-D velocity models below a local seismic network: example from the Pyrenees

NASA Astrophysics Data System (ADS)

Theunissen, T.; Chevrot, S.; Sylvander, M.; Monteiller, V.; Calvet, M.; Villaseñor, A.; Benahmed, S.; Pauchet, H.; Grimaud, F.

2018-03-01

Local seismic networks are usually designed so that earthquakes are located inside them (primary azimuthal gap <<180°) and close to the seismic stations (0-100 km). With these local or near-regional networks (0°-5°), many seismological observatories still routinely locate earthquakes using 1-D velocity models. Moving towards 3-D location algorithms requires robust 3-D velocity models. This work takes advantage of seismic monitoring spanning more than 30 yr in the Pyrenean region. We investigate the influence of a well-designed 3-D model with station corrections including basins structure and the geometry of the Mohorovicic discontinuity on earthquake locations. In the most favourable cases (GAP < 180° and distance to the first station lower than 15 km), results using 1-D velocity models are very similar to 3-D results. The horizontal accuracy in the 1-D case can be higher than in the 3-D case if lateral variations in the structure are not properly resolved. Depth is systematically better resolved in the 3-D model even on the boundaries of the seismic network (GAP > 180° and distance to the first station higher than 15 km). Errors on velocity models and accuracy of absolute earthquake locations are assessed based on a reference data set made of active seismic, quarry blasts and passive temporary experiments. Solutions and uncertainties are estimated using the probabilistic approach of the NonLinLoc (NLLoc) software based on Equal Differential Time. Some updates have been added to NLLoc to better focus on the final solution (outlier exclusion, multiscale grid search, S-phases weighting). Errors in the probabilistic approach are defined to take into account errors on velocity models and on arrival times. The seismicity in the final 3-D catalogue is located with a horizontal uncertainty of about 2.0 ± 1.9 km and a vertical uncertainty of about 3.0 ± 2.0 km.

The optimisation approach of ALARA in nuclear practice: an early application of the precautionary principle. Scientific uncertainty versus legal uncertainty.

PubMed

Lierman, S; Veuchelen, L

2005-01-01

The late health effects of exposure to low doses of ionising radiation are subject to scientific controversy: one view finds threats of high cancer incidence exaggerated, while the other view thinks the effects are underestimated. Both views have good scientific arguments in favour of them. Since the nuclear field, both industry and medicine have had to deal with this controversy for many decades. One can argue that the optimisation approach to keep the effective doses as low as reasonably achievable, taking economic and social factors into account (ALARA), is a precautionary approach. However, because of these stochastic effects, no scientific proof can be provided. This paper explores how ALARA and the Precautionary Principle are influential in the legal field and in particular in tort law, because liability should be a strong incentive for safer behaviour. This so-called "deterrence effect" of liability seems to evaporate in today's technical and highly complex society, in particular when dealing with the late health effects of low doses of ionising radiation. Two main issues will be dealt with in the paper: 1. How are the health risks attributable to "low doses" of radiation regulated in nuclear law and what lessons can be learned from the field of radiation protection? 2. What does ALARA have to inform the discussion of the Precautionary Principle and vice-versa, in particular, as far as legal sanctions and liability are concerned? It will be shown that the Precautionary Principle has not yet been sufficiently implemented into nuclear law.

Superconductivity proximate to antiferromagnetism in a copper-oxide monolayer grown on Bi2Sr2CaCu2O8 +δ

NASA Astrophysics Data System (ADS)

Wang, Shuai; Zhang, Long; Wang, Fa

2018-01-01

A nodeless superconducting (SC) gap was reported in a recent scanning tunneling spectroscopy experiment of a copper-oxide monolayer grown on a Bi2Sr2CaCu2O8 +δ (Bi2212) substrate [Zhong et al., Sci. Bull. 61, 1239 (2016), 10.1007/s11434-016-1145-4], which is in stark contrast to the nodal d -wave pairing gap in the bulk cuprates. Motivated by this experiment, we first show with first-principles calculations that the tetragonal CuO (T-CuO) monolayer on the Bi2212 substrate is more stable than the commonly postulated CuO2 structure. The T-CuO monolayer is composed of two CuO2 layers sharing the same O atoms. The band structure is obtained by first-principles calculations, and its strong electron correlation is treated with the renormalized mean-field theory. We argue that one CuO2 sublattice is hole doped while the other sublattice remains half filled and may have antiferromagnetic (AF) order. The doped Cu sublattice can show d -wave SC; however, its proximity to the AF Cu sublattice induces a spin-dependent hopping, which splits the Fermi surface and may lead to a full SC gap. Therefore, the nodeless SC gap observed in the experiment could be accounted for by the d -wave SC proximity to an AF order, thus it is extrinsic rather than intrinsic to the CuO2 layers.

75 FR 934 - Treatment by the Federal Deposit Insurance Corporation as Conservator or Receiver of Financial...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-07

... accounting principles (``GAAP''). The rule was a clarification, rather than a limitation, of the repudiation... has created uncertainty for securitization participants. On June 12, 2009, the Financial Accounting Standards Board (``FASB'') finalized modifications to GAAP through Statement of Financial Accounting...

Quantum Theory from Observer's Mathematics Point of View

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khots, Dmitriy; Khots, Boris

2010-05-04

This work considers the linear (time-dependent) Schrodinger equation, quantum theory of two-slit interference, wave-particle duality for single photons, and the uncertainty principle in a setting of arithmetic, algebra, and topology provided by Observer's Mathematics, see [1]. Certain theoretical results and communications pertaining to these theorems are also provided.

STRATEGIC PLAN FOR THE OFFICE OF RESEARCH AND DEVELOPMENT, MAY 1996

EPA Science Inventory

The ORD Strategic Plan is based on nine principles: (1) Focus research on the greatest risks to people and the environment, (2) Focus research on reducing uncertainty in risk assessment, (3) Balance human health and ecological research, (4) Work for customers and clients, (5) Mai...

Quantum Theory, the Uncertainty Principle, and the Alchemy of Standardized Testing.

ERIC Educational Resources Information Center

Wassermann, Selma

2001-01-01

Argues that reliance on the outcome of quantitative standardized tests to assess student performance is misplaced quest for certainty in an uncertain world. Reviews and lauds Canadian teacher-devised qualitative diagnostic tool, "Profiles of Student Behaviors," composed of 20 behavioral patterns in student knowledge, attitude, and skill.…

Water System Adaptation To Hydrological Changes: Module 9, Water System Resilience and Security under Hydrologic Variability and Uncertainty

EPA Science Inventory

This course will introduce students to the fundamental principles of water system adaptation to hydrological changes, with emphasis on data analysis and interpretation, technical planning, and computational modeling. Starting with real-world scenarios and adaptation needs, the co...

Using self-organizing maps to infill missing data in hydro-meteorological time series from the Logone catchment, Lake Chad basin.

PubMed

Nkiaka, E; Nawaz, N R; Lovett, J C

2016-07-01

Hydro-meteorological data is an important asset that can enhance management of water resources. But existing data often contains gaps, leading to uncertainties and so compromising their use. Although many methods exist for infilling data gaps in hydro-meteorological time series, many of these methods require inputs from neighbouring stations, which are often not available, while other methods are computationally demanding. Computing techniques such as artificial intelligence can be used to address this challenge. Self-organizing maps (SOMs), which are a type of artificial neural network, were used for infilling gaps in a hydro-meteorological time series in a Sudano-Sahel catchment. The coefficients of determination obtained were all above 0.75 and 0.65 while the average topographic error was 0.008 and 0.02 for rainfall and river discharge time series, respectively. These results further indicate that SOMs are a robust and efficient method for infilling missing gaps in hydro-meteorological time series.

Alkaline-stable nickel manganese oxides with ideal band gap for solar fuel photoanodes

DOE PAGES

Suram, Santosh K.; Zhou, Lan; Shinde, Aniketa; ...

2018-01-01

Combinatorial photoelectrochemistry combined with first principles calculations demonstrate that NiMnO 3 and its mixture with Ni 6 MnO 8 are photoanodes with phenomenal absorptivity and band alignment to the oxygen evolution reaction.

Alkaline-stable nickel manganese oxides with ideal band gap for solar fuel photoanodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suram, Santosh K.; Zhou, Lan; Shinde, Aniketa

Combinatorial photoelectrochemistry combined with first principles calculations demonstrate that NiMnO 3 and its mixture with Ni 6 MnO 8 are photoanodes with phenomenal absorptivity and band alignment to the oxygen evolution reaction.

Differentiating intolerance of uncertainty from three related but distinct constructs.

PubMed

Rosen, Natalie O; Ivanova, Elena; Knäuper, Bärbel

2014-01-01

Individual differences in uncertainty have been associated with heightened anxiety, stress and approach-oriented coping. Intolerance of uncertainty (IU) is a trait characteristic that arises from negative beliefs about uncertainty and its consequences. Researchers have established the central role of IU in the development of problematic worry and maladaptive coping, highlighting the importance of this construct to anxiety disorders. However, there is a need to improve our understanding of the phenomenology of IU. The goal of this paper was to present hypotheses regarding the similarities and differences between IU and three related constructs--intolerance of ambiguity, uncertainty orientation, and need for cognitive closure--and to call for future empirical studies to substantiate these hypotheses. To assist with achieving this goal, we conducted a systematic review of the literature, which also served to identify current gaps in knowledge. This paper differentiates these constructs by outlining each definition and general approaches to assessment, reviewing the existing empirical relations, and proposing theoretical similarities and distinctions. Findings may assist researchers in selecting the appropriate construct to address their research questions. Future research directions for the application of these constructs, particularly within the field of clinical and health psychology, are discussed.

The first determination of the Planck constant with the joule balance NIM-2

NASA Astrophysics Data System (ADS)

Li, Zhengkun; Zhang, Zhonghua; Lu, Yunfeng; Hu, Pengcheng; Liu, Yongmeng; Xu, Jinxin; Bai, Yang; Zeng, Tao; Wang, Gang; You, Qiang; Wang, Dawei; Li, Shisong; He, Qing; Tan, Jiubin

2017-10-01

The National Institute of Metrology (NIM, China) proposed a joule balance method to measure the Planck constant in 2006, and built the first prototype NIM-1 to verify its principle with a relative uncertainty of 8.9  ×  10-6 by 2013. Since 2013, a new joule balance NIM-2 has been designed, with a series of improvements to reduce the measurement uncertainty. By April 2017, NIM-2 has been constructed and can be employed to measure the Planck constant in vacuum. A first measurement on NIM-2 yields a determination of the Planck constant is 6.626 069 2(16)  ×  10-34 Js with a relative uncertainty of 2.4  ×  10-7. The determination differs in relative terms by  -1.27  ×  10-7 from the CODATA 2014 value. Further improvement of NIM-2 is still in progress towards 10-8 level uncertainty in the future.

Quantum speed limits: from Heisenberg’s uncertainty principle to optimal quantum control

NASA Astrophysics Data System (ADS)

Deffner, Sebastian; Campbell, Steve

2017-11-01

One of the most widely known building blocks of modern physics is Heisenberg’s indeterminacy principle. Among the different statements of this fundamental property of the full quantum mechanical nature of physical reality, the uncertainty relation for energy and time has a special place. Its interpretation and its consequences have inspired continued research efforts for almost a century. In its modern formulation, the uncertainty relation is understood as setting a fundamental bound on how fast any quantum system can evolve. In this topical review we describe important milestones, such as the Mandelstam-Tamm and the Margolus-Levitin bounds on the quantum speed limit, and summarise recent applications in a variety of current research fields—including quantum information theory, quantum computing, and quantum thermodynamics amongst several others. To bring order and to provide an access point into the many different notions and concepts, we have grouped the various approaches into the minimal time approach and the geometric approach, where the former relies on quantum control theory, and the latter arises from measuring the distinguishability of quantum states. Due to the volume of the literature, this topical review can only present a snapshot of the current state-of-the-art and can never be fully comprehensive. Therefore, we highlight but a few works hoping that our selection can serve as a representative starting point for the interested reader.

Implications of elevated CO2 on pelagic carbon fluxes in an Arctic mesocosm study - an elemental mass balance approach

NASA Astrophysics Data System (ADS)

Czerny, J.; Schulz, K. G.; Boxhammer, T.; Bellerby, R. G. J.; Büdenbender, J.; Engel, A.; Krug, S. A.; Ludwig, A.; Nachtigall, K.; Nondal, G.; Niehoff, B.; Silyakova, A.; Riebesell, U.

2013-05-01

Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental budgets. In practice, attempts to budget mesocosm enclosures are often hampered by uncertainties in some of the measured pools and fluxes, in particular due to uncertainties in constraining air-sea gas exchange, particle sinking, and wall growth. In an Arctic mesocosm study on ocean acidification applying KOSMOS (Kiel Off-Shore Mesocosms for future Ocean Simulation), all relevant element pools and fluxes of carbon, nitrogen and phosphorus were measured, using an improved experimental design intended to narrow down the mentioned uncertainties. Water-column concentrations of particulate and dissolved organic and inorganic matter were determined daily. New approaches for quantitative estimates of material sinking to the bottom of the mesocosms and gas exchange in 48 h temporal resolution as well as estimates of wall growth were developed to close the gaps in element budgets. However, losses elements from the budgets into a sum of insufficiently determined pools were detected, and are principally unavoidable in mesocosm investigation. The comparison of variability patterns of all single measured datasets revealed analytic precision to be the main issue in determination of budgets. Uncertainties in dissolved organic carbon (DOC), nitrogen (DON) and particulate organic phosphorus (POP) were much higher than the summed error in determination of the same elements in all other pools. With estimates provided for all other major elemental pools, mass balance calculations could be used to infer the temporal development of DOC, DON and POP pools. Future elevated pCO2 was found to enhance net autotrophic community carbon uptake in two of the three experimental phases but did not significantly affect particle elemental composition. Enhanced carbon consumption appears to result in accumulation of dissolved organic carbon under nutrient-recycling summer conditions. This carbon over-consumption effect becomes evident from mass balance calculations, but was too small to be resolved by direct measurements of dissolved organic matter. Faster nutrient uptake by comparatively small algae at high CO2 after nutrient addition resulted in reduced production rates under future ocean CO2 conditions at the end of the experiment. This CO2 mediated shift towards smaller phytoplankton and enhanced cycling of dissolved matter restricted the development of larger phytoplankton, thus pushing the system towards a retention type food chain with overall negative effects on export potential.

A precautionary principle for dual use research in the life sciences.

PubMed

Kuhlau, Frida; Höglund, Anna T; Evers, Kathinka; Eriksson, Stefan

2011-01-01

Most life science research entails dual-use complexity and may be misused for harmful purposes, e.g. biological weapons. The Precautionary Principle applies to special problems characterized by complexity in the relationship between human activities and their consequences. This article examines whether the principle, so far mainly used in environmental and public health issues, is applicable and suitable to the field of dual-use life science research. Four central elements of the principle are examined: threat, uncertainty, prescription and action. Although charges against the principle exist - for example that it stifles scientific development, lacks practical applicability and is poorly defined and vague - the analysis concludes that a Precautionary Principle is applicable to the field. Certain factors such as credibility of the threat, availability of information, clear prescriptive demands on responsibility and directives on how to act, determine the suitability and success of a Precautionary Principle. Moreover, policy-makers and researchers share a responsibility for providing and seeking information about potential sources of harm. A central conclusion is that the principle is meaningful and useful if applied as a context-dependent moral principle and allowed flexibility in its practical use. The principle may then inspire awareness-raising and the establishment of practical routines which appropriately reflect the fact that life science research may be misused for harmful purposes. © 2009 Blackwell Publishing Ltd.

Pharmaceutical new product development: the increasing role of in-licensing.

PubMed

Edwards, Nancy V

2008-12-01

Many pharmaceutical companies are facing a pipeline gap because of the increasing economic burden and uncertainty associated with internal research and development programs designed to develop new pharmaceutical products. To fill this pipeline gap, pharmaceutical companies are increasingly relying on in-licensing opportunities. New business development identifies new pharmaceuticals that satisfy unmet needs and are a good strategic fit for the company, completes valuation models and forecasts, evaluates the ability of the company to develop and launch products, and pursues in-licensing agreements for pharmaceuticals that cannot be developed internally on a timely basis. These agreements involve the transfer of access rights for patents, trademarks, or similar intellectual property from an outside company in exchange for payments. Despite the risks, in-licensing is increasingly becoming the preferred method for pharmaceutical companies with pipeline gaps to bring new pharmaceuticals to the clinician.

Development of Bipolar Pulse Accelerator for Pulsed Ion Beam Implantation to Semiconductor

NASA Astrophysics Data System (ADS)

Masugata, Katsumi; Kawahara, Yoshihiro; Mitsui, Chihiro; Kitamura, Iwao; Takahashi, Takakazu; Tanaka, Yasunori; Tanoue, Hisao; Arai, Kazuo

2002-12-01

To improve the purity of the ion beams new type of pulsed power ion accelerator named "bipolar pulse accelerator" was proposed. The accelerator consists of two acceleration gaps (an ion source gap and a post acceleration gap) and a drift tube, and a bipolar pulse is applied to the drift tube to accelerate the beam. In the accelerator intended ions are selectively accelerated and the purity of the ion beam is enhanced. As the first step of the development of the accelerator, a Br-type magnetically insulated acceleration gap is developed. The gap has an ion source of coaxial gas puff plasma gun on the grounded anode and a negative pulse is applied to the cathode to accelerate the ion beam. By using the plasma gun, ion source plasma (nitrogen) of current density around 100 A/cm2 is obtained. In the paper, the experimental results of the evaluation of the ion beam and the characteristics of the gap are shown with the principle and the design concept of the proposed accelerator.

Functionalized Thallium Antimony Films as Excellent Candidates for Large-Gap Quantum Spin Hall Insulator

PubMed Central

Zhang, Run-wu; Zhang, Chang-wen; Ji, Wei-xiao; Li, Sheng-shi; Yan, Shi-shen; Li, Ping; Wang, Pei-ji

2016-01-01

Group III-V films are of great importance for their potential application in spintronics and quantum computing. Search for two-dimensional III-V films with a nontrivial large-gap are quite crucial for the realization of dissipationless transport edge channels using quantum spin Hall (QSH) effects. Here we use first-principles calculations to predict a class of large-gap QSH insulators in functionalized TlSb monolayers (TlSbX2; (X = H, F, Cl, Br, I)), with sizable bulk gaps as large as 0.22 ~ 0.40 eV. The QSH state is identified by Z2 topological invariant together with helical edge states induced by spin-orbit coupling (SOC). Noticeably, the inverted band gap in the nontrivial states can be effectively tuned by the electric field and strain. Additionally, these films on BN substrate also maintain a nontrivial QSH state, which harbors a Dirac cone lying within the band gap. These findings may shed new light in future design and fabrication of QSH insulators based on two-dimensional honeycomb lattices in spintronics. PMID:26882865

Steric engineering of metal-halide perovskites with tunable optical band gaps

NASA Astrophysics Data System (ADS)

Filip, Marina R.; Eperon, Giles E.; Snaith, Henry J.; Giustino, Feliciano

2014-12-01

Owing to their high energy-conversion efficiency and inexpensive fabrication routes, solar cells based on metal-organic halide perovskites have rapidly gained prominence as a disruptive technology. An attractive feature of perovskite absorbers is the possibility of tailoring their properties by changing the elemental composition through the chemical precursors. In this context, rational in silico design represents a powerful tool for mapping the vast materials landscape and accelerating discovery. Here we show that the optical band gap of metal-halide perovskites, a key design parameter for solar cells, strongly correlates with a simple structural feature, the largest metal-halide-metal bond angle. Using this descriptor we suggest continuous tunability of the optical gap from the mid-infrared to the visible. Precise band gap engineering is achieved by controlling the bond angles through the steric size of the molecular cation. On the basis of these design principles we predict novel low-gap perovskites for optimum photovoltaic efficiency, and we demonstrate the concept of band gap modulation by synthesising and characterising novel mixed-cation perovskites.

Functionalized Thallium Antimony Films as Excellent Candidates for Large-Gap Quantum Spin Hall Insulator.

PubMed

Zhang, Run-wu; Zhang, Chang-wen; Ji, Wei-xiao; Li, Sheng-shi; Yan, Shi-shen; Li, Ping; Wang, Pei-ji

2016-02-17

Group III-V films are of great importance for their potential application in spintronics and quantum computing. Search for two-dimensional III-V films with a nontrivial large-gap are quite crucial for the realization of dissipationless transport edge channels using quantum spin Hall (QSH) effects. Here we use first-principles calculations to predict a class of large-gap QSH insulators in functionalized TlSb monolayers (TlSbX2; (X = H, F, Cl, Br, I)), with sizable bulk gaps as large as 0.22~0.40 eV. The QSH state is identified by Z2 topological invariant together with helical edge states induced by spin-orbit coupling (SOC). Noticeably, the inverted band gap in the nontrivial states can be effectively tuned by the electric field and strain. Additionally, these films on BN substrate also maintain a nontrivial QSH state, which harbors a Dirac cone lying within the band gap. These findings may shed new light in future design and fabrication of QSH insulators based on two-dimensional honeycomb lattices in spintronics.

Compact nanomechanical plasmonic phase modulators [Ultracompact nano-mechanical plasmonic phase modulators

DOE PAGES

Dennis, B. S.; Haftel, M. I.; Czaplewski, D. A.; ...

2015-03-30

Highly confined optical energy in plasmonic devices is advancing miniaturization in photonics. However, for mode sizes approaching ≈10 nm, the energy increasingly shifts into the metal, raising losses and hindering active phase modulation. Here, we propose a nanoelectromechanical phase-modulation principle exploiting the extraordinarily strong dependence of the phase velocity of metal–insulator–metal gap plasmons on dynamically variable gap size. We experimentally demonstrate a 23-μm-long non-resonant modulator having a 1.5π rad range, with 1.7 dB excess loss at 780 nm. Analysis shows that by simultaneously decreasing the gap, length and width, an ultracompact-footprint π rad phase modulator can be realized. This ismore » achieved without incurring the extra loss expected for plasmons confined in a decreasing gap, because the increasing phase-modulation strength from a narrowing gap offsets rising propagation losses. Here, such small, high-density electrically controllable components may find applications in optical switch fabrics and reconfigurable plasmonic optics.« less

New group-V elemental bilayers: A tunable structure model with four-, six-, and eight-atom rings

NASA Astrophysics Data System (ADS)

Kong, Xiangru; Li, Linyang; Leenaerts, Ortwin; Liu, Xiong-Jun; Peeters, François M.

2017-07-01

Two-dimensional group-V elemental materials have attracted widespread attention due to their nonzero band gap while displaying high electron mobility. Using first-principles calculations, we propose a series of new elemental bilayers with group-V elements (Bi, Sb, As). Our study reveals the dynamical stability of four-, six-, and eight-atom ring structures, demonstrating their possible coexistence in such bilayer systems. The proposed structures for Sb and As are large-gap semiconductors that are potentially interesting for applications in future nanodevices. The Bi structures have nontrivial topological properties with a direct nontrivial band gap. The nontrivial gap is shown to arise from a band inversion at the Brillouin zone center due to the strong intrinsic spin-orbit coupling in Bi atoms. Moreover, we demonstrate the possibility of tuning the properties of these materials by enhancing the ratio of six-atom rings to four- and eight-atom rings, which results in wider nontrivial band gaps and lower formation energies.

Interior Permanent Magnet Reluctance Machine with Brushless Field Excitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiles, R.H.

2005-10-07

In a conventional permanent magnet (PM) machine, the air-gap flux produced by the PM is fixed. It is difficult to enhance the air-gap flux density due to limitations of the PM in a series-magnetic circuit. However, the air-gap flux density can be weakened by using power electronic field weakening to the limit of demagnetization of the PMs. This paper presents the test results of controlling the PM air-gap flux density through the use of a stationary brushless excitation coil in a reluctance interior permanent magnet with brushless field excitation (RIPM-BFE) motor. Through the use of this technology the air-gap fluxmore » density can be either enhanced or weakened. There is no concern with demagnetizing the PMs during field weakening. The leakage flux of the excitation coil through the PMs is blocked. The prototype motor built on this principle confirms the concept of flux enhancement and weakening through the use of excitation coils.« less

Preliminary analysis of Dione Regio, Venus: The final Magellan regional imaging gap

NASA Technical Reports Server (NTRS)

Keddie, S. T.

1993-01-01

In Sep. 1992, the Magellan spacecraft filled the final large gap in its coverage of Venus when it imaged an area west of Alpha Regio. F-BIDR's and some test MIDR's of parts of this area were available as of late December. Dione Regio was imaged by the Arecibo observatory and a preliminary investigation of Magellan images supports the interpretations made based on these earlier images: Dione Regio is a regional highland on which is superposed three large, very distinct volcanic edifices. The superior resolution and different viewing geometry of the Magellan images also clarified some uncertainties and revealed fascinating details about this region.

Info-Gap Decision Theory for Assessing the Management of Catchments for Timber Production and Urban Water Supply

NASA Astrophysics Data System (ADS)

McCarthy, Michael A.; Lindenmayer, David B.

2007-04-01

While previous studies have examined how forest management is influenced by the risk of fire, they rely on probabilistic estimates of the occurrence and impacts of fire. However, nonprobabilistic approaches are required for assessing the importance of fire risk when data are poor but risks are appreciable. We explore impacts of fire risk on forest management using as a case study a water catchment in the Australian Capital Territory (ACT) (southeastern Australia). In this forested area, urban water supply and timber yields from exotic plantations are potential joint but also competing land uses. Our analyses were stimulated by extensive wildfires in early 2003 that burned much of the existing exotic pine plantation estate in the water catchment and the resulting need to explore the relative economic benefits of revegetating the catchment with exotic plantations or native vegetation. The current mean fire interval in the ACT is approximately 40 years, making the establishment of a pine plantation economically marginal at a 4% discount rate. However, the relative impact on water yield of revegetation with native species and pines is very uncertain, as is the risk of fire under climate change. We use info-gap decision theory to account for these nonprobabilistic sources of uncertainty, demonstrating that the decision that is most robust to uncertainty is highly sensitive to the cost of native revegetation. If costs of native revegetation are sufficiently small, this option is more robust to uncertainty than revegetation with a commercial pine plantation.

Info-gap decision theory for assessing the management of catchments for timber production and urban water supply.

PubMed

McCarthy, Michael A; Lindenmayer, David B

2007-04-01

While previous studies have examined how forest management is influenced by the risk of fire, they rely on probabilistic estimates of the occurrence and impacts of fire. However, nonprobabilistic approaches are required for assessing the importance of fire risk when data are poor but risks are appreciable. We explore impacts of fire risk on forest management using as a case study a water catchment in the Australian Capital Territory (ACT) (southeastern Australia). In this forested area, urban water supply and timber yields from exotic plantations are potential joint but also competing land uses. Our analyses were stimulated by extensive wildfires in early 2003 that burned much of the existing exotic pine plantation estate in the water catchment and the resulting need to explore the relative economic benefits of revegetating the catchment with exotic plantations or native vegetation. The current mean fire interval in the ACT is approximately 40 years, making the establishment of a pine plantation economically marginal at a 4% discount rate. However, the relative impact on water yield of revegetation with native species and pines is very uncertain, as is the risk of fire under climate change. We use info-gap decision theory to account for these nonprobabilistic sources of uncertainty, demonstrating that the decision that is most robust to uncertainty is highly sensitive to the cost of native revegetation. If costs of native revegetation are sufficiently small, this option is more robust to uncertainty than revegetation with a commercial pine plantation.

Classification of Tree Species in Overstorey Canopy of Subtropical Forest Using QuickBird Images.

PubMed

Lin, Chinsu; Popescu, Sorin C; Thomson, Gavin; Tsogt, Khongor; Chang, Chein-I

2015-01-01

This paper proposes a supervised classification scheme to identify 40 tree species (2 coniferous, 38 broadleaf) belonging to 22 families and 36 genera in high spatial resolution QuickBird multispectral images (HMS). Overall kappa coefficient (OKC) and species conditional kappa coefficients (SCKC) were used to evaluate classification performance in training samples and estimate accuracy and uncertainty in test samples. Baseline classification performance using HMS images and vegetation index (VI) images were evaluated with an OKC value of 0.58 and 0.48 respectively, but performance improved significantly (up to 0.99) when used in combination with an HMS spectral-spatial texture image (SpecTex). One of the 40 species had very high conditional kappa coefficient performance (SCKC ≥ 0.95) using 4-band HMS and 5-band VIs images, but, only five species had lower performance (0.68 ≤ SCKC ≤ 0.94) using the SpecTex images. When SpecTex images were combined with a Visible Atmospherically Resistant Index (VARI), there was a significant improvement in performance in the training samples. The same level of improvement could not be replicated in the test samples indicating that a high degree of uncertainty exists in species classification accuracy which may be due to individual tree crown density, leaf greenness (inter-canopy gaps), and noise in the background environment (intra-canopy gaps). These factors increase uncertainty in the spectral texture features and therefore represent potential problems when using pixel-based classification techniques for multi-species classification.

Development of machine-vision system for gap inspection of muskmelon grafted seedlings.

PubMed

Liu, Siyao; Xing, Zuochang; Wang, Zifan; Tian, Subo; Jahun, Falalu Rabiu

2017-01-01

Grafting robots have been developed in the world, but some auxiliary works such as gap-inspecting for grafted seedlings still need to be done by human. An machine-vision system of gap inspection for grafted muskmelon seedlings was developed in this study. The image acquiring system consists of a CCD camera, a lens and a front white lighting source. The image of inspected gap was processed and analyzed by software of HALCON 12.0. The recognition algorithm for the system is based on principle of deformable template matching. A template should be created from an image of qualified grafted seedling gap. Then the gap image of the grafted seedling will be compared with the created template to determine their matching degree. Based on the similarity between the gap image of grafted seedling and the template, the matching degree will be 0 to 1. The less similar for the grafted seedling gap with the template the smaller of matching degree. Thirdly, the gap will be output as qualified or unqualified. If the matching degree of grafted seedling gap and the template is less than 0.58, or there is no match is found, the gap will be judged as unqualified; otherwise the gap will be qualified. Finally, 100 muskmelon seedlings were grafted and inspected to test the gap inspection system. Results showed that the gap inspection machine-vision system could recognize the gap qualification correctly as 98% of human vision. And the inspection speed of this system can reach 15 seedlings·min-1. The gap inspection process in grafting can be fully automated with this developed machine-vision system, and the gap inspection system will be a key step of a fully-automatic grafting robots.

Unconventional nozzle tradeoff study. [space tug propulsion

NASA Technical Reports Server (NTRS)

Obrien, C. J.

1979-01-01

Plug cluster engine design, performance, weight, envelope, operational characteristics, development cost, and payload capability, were evaluated and comparisons were made with other space tug engine candidates using oxygen/hydrogen propellants. Parametric performance data were generated for existing developed or high technology thrust chambers clustered around a plug nozzle of very large diameter. The uncertainties in the performance prediction of plug cluster engines with large gaps between the modules (thrust chambers) were evaluated. The major uncertainty involves, the aerodynamics of the flow from discrete nozzles, and the lack of this flow to achieve the pressure ratio corresponding to the defined area ratio for a plug cluster. This uncertainty was reduced through a cluster design that consists of a plug contour that is formed from the cluster of high area ratio bell nozzles that have been scarfed. Light-weight, high area ratio, bell nozzles were achieved through the use of AGCarb (carbon-carbon cloth) nozzle extensions.

Incorporating uncertainty in watershed management decision-making: A mercury TMDL case study

USGS Publications Warehouse

Labiosa, W.; Leckie, J.; Shachter, R.; Freyberg, D.; Rytuba, J.; ,

2005-01-01

Water quality impairment due to high mercury fish tissue concentrations and high mercury aqueous concentrations is a widespread problem in several sub-watersheds that are major sources of mercury to the San Francisco Bay. Several mercury Total Maximum Daily Load regulations are currently being developed to address this problem. Decisions about control strategies are being made despite very large uncertainties about current mercury loading behavior, relationships between total mercury loading and methyl mercury formation, and relationships between potential controls and mercury fish tissue levels. To deal with the issues of very large uncertainties, data limitations, knowledge gaps, and very limited State agency resources, this work proposes a decision analytical alternative for mercury TMDL decision support. The proposed probabilistic decision model is Bayesian in nature and is fully compatible with a "learning while doing" adaptive management approach. Strategy evaluation, sensitivity analysis, and information collection prioritization are examples of analyses that can be performed using this approach.

Estimating uncertainties in complex joint inverse problems

NASA Astrophysics Data System (ADS)

Afonso, Juan Carlos

2016-04-01

Sources of uncertainty affecting geophysical inversions can be classified either as reflective (i.e. the practitioner is aware of her/his ignorance) or non-reflective (i.e. the practitioner does not know that she/he does not know!). Although we should be always conscious of the latter, the former are the ones that, in principle, can be estimated either empirically (by making measurements or collecting data) or subjectively (based on the experience of the researchers). For complex parameter estimation problems in geophysics, subjective estimation of uncertainty is the most common type. In this context, probabilistic (aka Bayesian) methods are commonly claimed to offer a natural and realistic platform from which to estimate model uncertainties. This is because in the Bayesian approach, errors (whatever their nature) can be naturally included as part of the global statistical model, the solution of which represents the actual solution to the inverse problem. However, although we agree that probabilistic inversion methods are the most powerful tool for uncertainty estimation, the common claim that they produce "realistic" or "representative" uncertainties is not always justified. Typically, ALL UNCERTAINTY ESTIMATES ARE MODEL DEPENDENT, and therefore, besides a thorough characterization of experimental uncertainties, particular care must be paid to the uncertainty arising from model errors and input uncertainties. We recall here two quotes by G. Box and M. Gunzburger, respectively, of special significance for inversion practitioners and for this session: "…all models are wrong, but some are useful" and "computational results are believed by no one, except the person who wrote the code". In this presentation I will discuss and present examples of some problems associated with the estimation and quantification of uncertainties in complex multi-observable probabilistic inversions, and how to address them. Although the emphasis will be on sources of uncertainty related to the forward and statistical models, I will also address other uncertainties associated with data and uncertainty propagation.

THE DISTRIBUTION OF ORGANIC CARBON IN MAJOR COMPONENTS OF FORESTS LOCATED IN FIVE LIFE ZONES OF VENEZUELA

EPA Science Inventory

One of the major uncertainties concerning the role of tropical forests in the global carbon cycle is the lack of adequate data on the carbon content of all their components. The goal of this study was to contribute to filling this data gap by estimating the quantity of carbon in ...

Designing a mangrove research and demonstration forest in the Rufiji Delta, Tanzania

Treesearch

Mwita M. Mangora; Mwanahija S. Shalli; Immaculate S. Semesi; Marco A. Njana; Emmanuel J. Mwainunu; Jared E. Otieno; Elias Ntibasubile; Henry C. Mallya; Kusaga Mukama; Matiko Wambura; Nurdin A. Chamuya; Carl C. Trettin; Christina E. Stringer

2016-01-01

Despite the growing body of literature on science and management of mangroves, there is a considerable knowledge gap and uncertainty at local levels regarding the carbon pool size, variability of carbon sequestration and carbon stocks within mangrove forests, mechanisms that control carbon emissions from degradation of mangrove forests, impacts of conversion to other...

Addressing uncertainty: how to conserve and manage rare or little-known fungi

Treesearch

Randy Molina; Thomas R. Horton; James M. Trappe; Bruce G. Marcot

2011-01-01

One of the greater challenges in conserving fungi comes from our incomplete knowledge of degree of rarity, risk status, and habitat requirements of most fungal species. We discuss approaches to immediately begin closing knowledge gaps, including: (1) harnessing collective expert knowledge so that data from professional experiences (e.g., personal collection and...

Comparison of different objective functions for parameterization of simple respiration models

Treesearch

M.T. van Wijk; B. van Putten; D.Y. Hollinger; A.D. Richardson

2008-01-01

The eddy covariance measurements of carbon dioxide fluxes collected around the world offer a rich source for detailed data analysis. Simple, aggregated models are attractive tools for gap filling, budget calculation, and upscaling in space and time. Key in the application of these models is their parameterization and a robust estimate of the uncertainty and reliability...

Atmosphere, ocean, and land: Critical gaps in Earth system models

NASA Technical Reports Server (NTRS)

Prinn, Ronald G.; Hartley, Dana

1992-01-01

We briefly review current knowledge and pinpoint some of the major areas of uncertainty for the following fundamental processes: (1) convection, condensation nuclei, and cloud formation; (2) oceanic circulation and its coupling to the atmosphere and cryosphere; (3) land surface hydrology and hydrology-vegetation coupling; (4) biogeochemistry of greenhouse gases; and (5) upper atmospheric chemistry and circulation.

An integrated science plan for the Lake Tahoe basin: conceptual framework and research strategies

Treesearch

Zachary P. Hymanson; Michael W. Collopy

2010-01-01

An integrated science plan was developed to identify and refine contemporary science information needs for the Lake Tahoe basin ecosystem. The main objectives were to describe a conceptual framework for an integrated science program, and to develop research strategies addressing key uncertainties and information gaps that challenge government agencies in the theme...

Building Scientific Confidence in the Development and Evaluation of Read-Across - GenRA: Evaluating local validity for read-across prediction using chemical and biological information (SOT/QSAR conference)

EPA Science Inventory

Read-across remains a popular data gap filling technique within category and analogue approaches for regulatory purposes. Acceptance of read-across is an ongoing challenge with several efforts underway for identifying and addressing uncertainties. Here we demonstrate an algorithm...

Atomic scale origins of sub-band gap optical absorption in gold-hyperdoped silicon

NASA Astrophysics Data System (ADS)

Ferdous, Naheed; Ertekin, Elif

2018-05-01

Gold hyperdoped silicon exhibits room temperature sub band gap optical absorption, with potential applications as infrared absorbers/detectors and impurity band photovoltaics. We use first-principles density functional theory to establish the origins of the sub band gap response. Substitutional gold AuSi and substitutional dimers AuSi - AuSi are found to be the energetically preferred defect configurations, and AuSi gives rise to partially filled mid-gap defect bands well offset from the band edges. AuSi is predicted to offer substantial sub-band gap absorption, exceeding that measured in prior experiments by two orders of magnitude for similar Au concentration. This suggests that in experimentally realized systems, in addition to AuSi, the implanted gold is accommodated by the lattice in other ways, including other defect complexes and gold precipitates. We further identify that it is energetically favorable for isolated AuSi to form AuSi - AuSi, which by contrast do not exhibit mid-gap states. The formation of dimers and other complexes could serve as nuclei in the earliest stages of Au precipitation, which may be responsible for the observed rapid deactivation of sub-band gap response upon annealing.

Accounting for uncertainty in health economic decision models by using model averaging.

PubMed

Jackson, Christopher H; Thompson, Simon G; Sharples, Linda D

2009-04-01

Health economic decision models are subject to considerable uncertainty, much of which arises from choices between several plausible model structures, e.g. choices of covariates in a regression model. Such structural uncertainty is rarely accounted for formally in decision models but can be addressed by model averaging. We discuss the most common methods of averaging models and the principles underlying them. We apply them to a comparison of two surgical techniques for repairing abdominal aortic aneurysms. In model averaging, competing models are usually either weighted by using an asymptotically consistent model assessment criterion, such as the Bayesian information criterion, or a measure of predictive ability, such as Akaike's information criterion. We argue that the predictive approach is more suitable when modelling the complex underlying processes of interest in health economics, such as individual disease progression and response to treatment.

Measuring uncertainty by extracting fuzzy rules using rough sets

NASA Technical Reports Server (NTRS)

Worm, Jeffrey A.

1991-01-01

Despite the advancements in the computer industry in the past 30 years, there is still one major deficiency. Computers are not designed to handle terms where uncertainty is present. To deal with uncertainty, techniques other than classical logic must be developed. The methods are examined of statistical analysis, the Dempster-Shafer theory, rough set theory, and fuzzy set theory to solve this problem. The fundamentals of these theories are combined to possibly provide the optimal solution. By incorporating principles from these theories, a decision making process may be simulated by extracting two sets of fuzzy rules: certain rules and possible rules. From these rules a corresponding measure of how much these rules is believed is constructed. From this, the idea of how much a fuzzy diagnosis is definable in terms of a set of fuzzy attributes is studied.

First-Principles Calculation of the Third Virial Coefficient of Helium

PubMed Central

Garberoglio, Giovanni; Harvey, Allan H.

2009-01-01

Knowledge of the pair and three-body potential-energy surfaces of helium is now sufficient to allow calculation of the third density virial coefficient, C(T), with significantly smaller uncertainty than that of existing experimental data. In this work, we employ the best available pair and three-body potentials for helium and calculate C(T) with path-integral Monte Carlo (PIMC) calculations supplemented by semiclassical calculations. The values of C(T) presented extend from 24.5561 K to 10 000 K. In the important metrological range of temperatures near 273.16 K, our uncertainties are smaller than the best experimental results by approximately an order of magnitude, and the reduction in uncertainty at other temperatures is at least as great. For convenience in calculation of C(T) and its derivatives, a simple correlating equation is presented. PMID:27504226

Mapping and uncertainty analysis of energy and pitch angle phase space in the DIII-D fast ion loss detector.

PubMed

Pace, D C; Pipes, R; Fisher, R K; Van Zeeland, M A

2014-11-01

New phase space mapping and uncertainty analysis of energetic ion loss data in the DIII-D tokamak provides experimental results that serve as valuable constraints in first-principles simulations of energetic ion transport. Beam ion losses are measured by the fast ion loss detector (FILD) diagnostic system consisting of two magnetic spectrometers placed independently along the outer wall. Monte Carlo simulations of mono-energetic and single-pitch ions reaching the FILDs are used to determine the expected uncertainty in the measurements. Modeling shows that the variation in gyrophase of 80 keV beam ions at the FILD aperture can produce an apparent measured energy signature spanning across 50-140 keV. These calculations compare favorably with experiments in which neutral beam prompt loss provides a well known energy and pitch distribution.

Uncertainties in Air Exchange using Continuous-Injection, Long-Term Sampling Tracer-Gas Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sherman, Max H.; Walker, Iain S.; Lunden, Melissa M.

2013-12-01

The PerFluorocarbon Tracer (PFT) method is a low-cost approach commonly used for measuring air exchange in buildings using tracer gases. It is a specific application of the more general Continuous-Injection, Long-Term Sampling (CILTS) method. The technique is widely used but there has been little work on understanding the uncertainties (both precision and bias) associated with its use, particularly given that it is typically deployed by untrained or lightly trained people to minimize experimental costs. In this article we will conduct a first-principles error analysis to estimate the uncertainties and then compare that analysis to CILTS measurements that were over-sampled, throughmore » the use of multiple tracers and emitter and sampler distribution patterns, in three houses. We find that the CILTS method can have an overall uncertainty of 10-15percent in ideal circumstances, but that even in highly controlled field experiments done by trained experimenters expected uncertainties are about 20percent. In addition, there are many field conditions (such as open windows) where CILTS is not likely to provide any quantitative data. Even avoiding the worst situations of assumption violations CILTS should be considered as having a something like a ?factor of two? uncertainty for the broad field trials that it is typically used in. We provide guidance on how to deploy CILTS and design the experiment to minimize uncertainties.« less

Analysis and Design of Launch Vehicle Flight Control Systems

NASA Technical Reports Server (NTRS)

Wie, Bong; Du, Wei; Whorton, Mark

2008-01-01

This paper describes the fundamental principles of launch vehicle flight control analysis and design. In particular, the classical concept of "drift-minimum" and "load-minimum" control principles is re-examined and its performance and stability robustness with respect to modeling uncertainties and a gimbal angle constraint is discussed. It is shown that an additional feedback of angle-of-attack or lateral acceleration can significantly improve the overall performance and robustness, especially in the presence of unexpected large wind disturbance. Non-minimum-phase structural filtering of "unstably interacting" bending modes of large flexible launch vehicles is also shown to be effective and robust.

The quantum limit for gravitational-wave detectors and methods of circumventing it

NASA Technical Reports Server (NTRS)

Thorne, K. S.; Caves, C. M.; Sandberg, V. D.; Zimmermann, M.; Drever, R. W. P.

1979-01-01

The Heisenberg uncertainty principle prevents the monitoring of the complex amplitude of a mechanical oscillator more accurately than a certain limit value. This 'quantum limit' is a serious obstacle to the achievement of a 10 to the -21st gravitational-wave detection sensitivity. This paper examines the principles of the back-action evasion technique and finds that this technique may be able to overcome the problem of the quantum limit. Back-action evasion does not solve, however, other problems of detection, such as weak coupling, large amplifier noise, and large Nyquist noise.

Experimental evolution of bet hedging under manipulated environmental uncertainty in Neurospora crassa.

PubMed

Graham, Jeffrey K; Smith, Myron L; Simons, Andrew M

2014-07-22

All organisms are faced with environmental uncertainty. Bet-hedging theory expects unpredictable selection to result in the evolution of traits that maximize the geometric-mean fitness even though such traits appear to be detrimental over the shorter term. Despite the centrality of fitness measures to evolutionary analysis, no direct test of the geometric-mean fitness principle exists. Here, we directly distinguish between predictions of competing fitness maximization principles by testing Cohen's 1966 classic bet-hedging model using the fungus Neurospora crassa. The simple prediction is that propagule dormancy will evolve in proportion to the frequency of 'bad' years, whereas the prediction of the alternative arithmetic-mean principle is the evolution of zero dormancy as long as the expectation of a bad year is less than 0.5. Ascospore dormancy fraction in N. crassa was allowed to evolve under five experimental selection regimes that differed in the frequency of unpredictable 'bad years'. Results were consistent with bet-hedging theory: final dormancy fraction in 12 genetic lineages across 88 independently evolving samples was proportional to the frequency of bad years, and evolved both upwards and downwards as predicted from a range of starting dormancy fractions. These findings suggest that selection results in adaptation to variable rather than to expected environments. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Folding behaviour of Tachi-Miura polyhedron bellows.

PubMed

Yasuda, Hiromi; Yein, Thu; Tachi, Tomohiro; Miura, Koryo; Taya, Minoru

2013-11-08

In this paper, we examine the folding behaviour of Tachi-Miura polyhedron (TMP) bellows made of paper, which is known as a rigid-foldable structure, and construct a theoretical model to predict the mechanical energy associated with the compression of TMP bellows, which is compared with the experimentally measured energy, resulting in the gap between the mechanical work by the compression force and the bending energy distributed along all the crease lines. The extended Hamilton's principle is applied to explain the gap which is considered to be energy dissipation in the mechanical behaviour of TMP bellows.

Chemical shift and zone-folding effects on the energy gaps of GaAs-AlAs (001) superlattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, S.B.; Cohen, M.L.; Louie, S.G.

1991-04-15

The chemical shift and zone-folding effects obtained from quasiparticle calculations for ultrathin GaAs-AlAs superlattices are incorporated within a Kronig-Penny model for superlattices of the arbitrary lattice period. We determine that superlattices with lattice periods in the range of 3{times}3 to 9{times}9 have an {ital X}-derived pseudodirect gap. This result explains both the results from first-principles calculations for ultrathin superlattices and those from experiments for a broader lattice period.

Physical insight into the thermodynamic uncertainty relation using Brownian motion in tilted periodic potentials

NASA Astrophysics Data System (ADS)

Hyeon, Changbong; Hwang, Wonseok

2017-07-01

Using Brownian motion in periodic potentials V (x ) tilted by a force f , we provide physical insight into the thermodynamic uncertainty relation, a recently conjectured principle for statistical errors and irreversible heat dissipation in nonequilibrium steady states. According to the relation, nonequilibrium output generated from dissipative processes necessarily incurs an energetic cost or heat dissipation q , and in order to limit the output fluctuation within a relative uncertainty ɛ , at least 2 kBT /ɛ2 of heat must be dissipated. Our model shows that this bound is attained not only at near-equilibrium [f ≪V'(x ) ] but also at far-from-equilibrium [f ≫V'(x ) ] , more generally when the dissipated heat is normally distributed. Furthermore, the energetic cost is maximized near the critical force when the barrier separating the potential wells is about to vanish and the fluctuation of Brownian particles is maximized. These findings indicate that the deviation of heat distribution from Gaussianity gives rise to the inequality of the uncertainty relation, further clarifying the meaning of the uncertainty relation. Our derivation of the uncertainty relation also recognizes a bound of nonequilibrium fluctuations that the variance of dissipated heat (σq2) increases with its mean (μq), and it cannot be smaller than 2 kBT μq .

Entropic uncertainty and measurement reversibility

NASA Astrophysics Data System (ADS)

Berta, Mario; Wehner, Stephanie; Wilde, Mark M.

2016-07-01

The entropic uncertainty relation with quantum side information (EUR-QSI) from (Berta et al 2010 Nat. Phys. 6 659) is a unifying principle relating two distinctive features of quantum mechanics: quantum uncertainty due to measurement incompatibility, and entanglement. In these relations, quantum uncertainty takes the form of preparation uncertainty where one of two incompatible measurements is applied. In particular, the ‘uncertainty witness’ lower bound in the EUR-QSI is not a function of a post-measurement state. An insightful proof of the EUR-QSI from (Coles et al 2012 Phys. Rev. Lett. 108 210405) makes use of a fundamental mathematical consequence of the postulates of quantum mechanics known as the non-increase of quantum relative entropy under quantum channels. Here, we exploit this perspective to establish a tightening of the EUR-QSI which adds a new state-dependent term in the lower bound, related to how well one can reverse the action of a quantum measurement. As such, this new term is a direct function of the post-measurement state and can be thought of as quantifying how much disturbance a given measurement causes. Our result thus quantitatively unifies this feature of quantum mechanics with the others mentioned above. We have experimentally tested our theoretical predictions on the IBM quantum experience and find reasonable agreement between our predictions and experimental outcomes.

Physical insight into the thermodynamic uncertainty relation using Brownian motion in tilted periodic potentials.

PubMed

Hyeon, Changbong; Hwang, Wonseok

2017-07-01

Using Brownian motion in periodic potentials V(x) tilted by a force f, we provide physical insight into the thermodynamic uncertainty relation, a recently conjectured principle for statistical errors and irreversible heat dissipation in nonequilibrium steady states. According to the relation, nonequilibrium output generated from dissipative processes necessarily incurs an energetic cost or heat dissipation q, and in order to limit the output fluctuation within a relative uncertainty ε, at least 2k_{B}T/ε^{2} of heat must be dissipated. Our model shows that this bound is attained not only at near-equilibrium [f≪V^{'}(x)] but also at far-from-equilibrium [f≫V^{'}(x)], more generally when the dissipated heat is normally distributed. Furthermore, the energetic cost is maximized near the critical force when the barrier separating the potential wells is about to vanish and the fluctuation of Brownian particles is maximized. These findings indicate that the deviation of heat distribution from Gaussianity gives rise to the inequality of the uncertainty relation, further clarifying the meaning of the uncertainty relation. Our derivation of the uncertainty relation also recognizes a bound of nonequilibrium fluctuations that the variance of dissipated heat (σ_{q}^{2}) increases with its mean (μ_{q}), and it cannot be smaller than 2k_{B}Tμ_{q}.

Investigation of electronic structures and optical properties of β -Si3N4 doped with IV A elements: A first-principles simulation

NASA Astrophysics Data System (ADS)

Lu, Xuefeng; Gao, Xu; Ren, Junqiang; Li, Cuixia; Guo, Xin; Wei, Yupeng; La, Peiqing

2018-04-01

Based on first-principles simulations with the generalized gradient approximation (GGA) of the Perdew-Burke-Ernzerhof (PBE) functional, we studied the electronic structures and optical properties of hexagonal silicon nitride (β-Si3N4) doped with IV A elements, C, Ge, Sn and Pb. It was found that the Ge-doped system is characterized by a more stable structure with a lower formation energy of 2.584 eV compared with those of the C-, Sn- and Pb-doped systems of 3.877 eV, 5.249 eV and 7.672 eV, respectively. The band gap (EG) of the Pb-doped system was the lowest at 1.6 eV, displaying semiconducting characteristics. Additionally, there was a transition from a direct band gap to an indirect band gap in the C-doped system. Charge difference density analysis showed that the covalent property of the C-N bonds was enhanced by expansion of the electron-free region and the larger Mulliken population values of 0.71 and 0.86. Furthermore, lower absorption and reflectivity peaks at 11.30 eV were observed for the C-doped system, demonstrating its broader potential for application in photoelectric and microelectronic devices.

Tuning of electronic band gaps and optoelectronic properties of binary strontium chalcogenides by means of doping of magnesium atom(s)- a first principles based theoretical initiative with mBJ, B3LYP and WC-GGA functionals

NASA Astrophysics Data System (ADS)

Debnath, Bimal; Sarkar, Utpal; Debbarma, Manish; Bhattacharjee, Rahul; Chattopadhyaya, Surya

2018-02-01

First principle based theoretical initiative is taken to tune the optoelectronic properties of binary strontium chalcogenide semiconductors by doping magnesium atom(s) into their rock-salt unit cells at specific concentrations x = 0.0, 0.25, 0.50, 0.75 and 1.0 and such tuning is established by studying structural, electronic and optical properties of designed binary compounds and ternary alloys employing WC-GGA, B3LYP and mBJ exchange-correlation functionals. Band structure of each compound is constructed and respective band gaps under all the potential schemes are measured. The band gap bowing and its microscopic origin are calculated using quadratic fit and Zunger's approach, respectively. The atomic and orbital origins of electronic states in the band structure of any compound are explored from its density of states. The nature of chemical bonds between the constituent atoms in each compound is explored from the valence electron density contour plots. Optical properties of any specimen are explored from the computed spectra of its dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity optical absorption and energy loss function. Several calculated results are compared with available experimental and earlier theoretical data.

First-principles thermodynamics study of phase stability in inorganic halide perovskite solid solutions

NASA Astrophysics Data System (ADS)

Bechtel, Jonathon S.; Van der Ven, Anton

2018-04-01

Halide substitution gives rise to a tunable band gap as a function of composition in halide perovskite materials. However, photoinduced phase segregation, observed at room temperature in mixed halide A Pb (IxBr1-x) 3 systems, limits open circuit voltages and decreases photovoltaic device efficiencies. We investigate equilibrium phase stability of orthorhombic P n m a γ -phase CsM (XxY1-x) 3 perovskites where M is Pb or Sn, and X and Y are Br, Cl, or I. Finite-temperature phase diagrams are constructed using a cluster expansion effective Hamiltonian parameterized from first-principles density-functional-theory calculations. Solid solution phases for CsM (IxBr1-x) 3 and CsM (BrxCl1-x) 3 are predicted to be stable well below room temperature while CsM (IxCl1-x) 3 systems have miscibility gaps that extend above 400 K. The height of the miscibility gap correlates with the difference in volume between end members. Also layered ground states are found on the convex hull at x =2 /3 for CsSnBr2Cl ,CsPbI2Br , and CsPbBrCl2. The impact of these ground states on the finite temperature phase diagram is discussed in the context of the experimentally observed photoinduced phase segregation.

Band-Gap Engineering at a Semiconductor-Crystalline Oxide Interface

DOE PAGES

Jahangir-Moghadam, Mohammadreza; Ahmadi-Majlan, Kamyar; Shen, Xuan; ...

2015-02-09

The epitaxial growth of crystalline oxides on semiconductors provides a pathway to introduce new functionalities to semiconductor devices. Key to integrating the functionalities of oxides onto semiconductors is controlling the band alignment at interfaces between the two materials. Here we apply principles of band gap engineering traditionally used at heterojunctions between conventional semiconductors to control the band offset between a single crystalline oxide and a semiconductor. Reactive molecular beam epitaxy is used to realize atomically abrupt and structurally coherent interfaces between SrZr xTi 1-xO₃ and Ge, in which the band gap of the former is enhanced with Zr content x.more » We present structural and electrical characterization of SrZr xTi 1-xO₃-Ge heterojunctions and demonstrate a type-I band offset can be achieved. These results demonstrate that band gap engineering can be exploited to realize functional semiconductor crystalline oxide heterojunctions.« less

Graphene-based half-metal and spin-semiconductor for spintronic applications.

PubMed

Qi, Jingshan; Chen, Xiaofang; Hu, Kaige; Feng, Ji

2016-03-31

In this letter we propose a strategy to make graphene become a half-metal or spin-semiconductor by combining the magnetic proximity effects and sublattice symmetry breaking in graphone/graphene and graphone/graphene/BN heterostructures. Exchange interactions lift the spin degeneracy and sublattice symmetry breaking opens a band gap in graphene. More interestingly, the gap opening depends on the spin direction and the competition between the sublattice asymmetry and exchange field determines the system is a half-metal or a spin-semiconductor. By first-principles calculations and a low-energy effective model analysis, we elucidate the underlying physical mechanism of spin-dependent gap opening and spin degeneracy splitting. This offers an alternative practical platform for graphene-based spintronics.

``From Fundamental Motives to Rational Expectation Equilibrium[REE, henceworth] of Indeterminacy''

NASA Astrophysics Data System (ADS)

Maksoed, Ssi, Wh-

For ``Principle of Indeterminacy''from Heisenberg states: ``one of the fundamental cornerstone of quantum mechanics is the Heisenberg uncertainty principle''.whereas canonically conjugate quantities can be determined simultaneously only with a characteristic indeterminacy[M. Arevalo Aguilar, et.al]. Accompanying Alfred North Whitehead conclusion in ``The Aims of Education''that mathematical symbols are artificial before new meanings given, two kinds of fundamental motives: (i) expectation-expectation, (ii) expectation-certainty inherently occurs with determinacy properties of rational expectation equilibrium(REE, henceworth)- Guido Ascari & Tizano Ropele:''Trend inflation, Taylor principle & Indeterminacy'', Kiel Institute, June 2007. Furthers, relative price expression can be compare of their α and (1 - α) configurations in the expression of possible activity. Acknowledgment to Prof[asc]. Dr. Bobby Eka Gunara for ``made a rank through physics'' denotes...

Quantum-memory-assisted entropic uncertainty relation in a Heisenberg XYZ chain with an inhomogeneous magnetic field

NASA Astrophysics Data System (ADS)

Wang, Dong; Huang, Aijun; Ming, Fei; Sun, Wenyang; Lu, Heping; Liu, Chengcheng; Ye, Liu

2017-06-01

The uncertainty principle provides a nontrivial bound to expose the precision for the outcome of the measurement on a pair of incompatible observables in a quantum system. Therefore, it is of essential importance for quantum precision measurement in the area of quantum information processing. Herein, we investigate quantum-memory-assisted entropic uncertainty relation (QMA-EUR) in a two-qubit Heisenberg \\boldsymbol{X}\\boldsymbol{Y}\\boldsymbol{Z} spin chain. Specifically, we observe the dynamics of QMA-EUR in a realistic model there are two correlated sites linked by a thermal entanglement in the spin chain with an inhomogeneous magnetic field. It turns out that the temperature, the external inhomogeneous magnetic field and the field inhomogeneity can lift the uncertainty of the measurement due to the reduction of the thermal entanglement, and explicitly higher temperature, stronger magnetic field or larger inhomogeneity of the field can result in inflation of the uncertainty. Besides, it is found that there exists distinct dynamical behaviors of the uncertainty for ferromagnetism \\boldsymbol{}≤ft(\\boldsymbol{J}<\\boldsymbol{0}\\right) and antiferromagnetism \\boldsymbol{}≤ft(\\boldsymbol{J}>\\boldsymbol{0}\\right) chains. Moreover, we also verify that the measuring uncertainty is dramatically anti-correlated with the purity of the bipartite spin system, the greater purity can result in the reduction of the measuring uncertainty, vice versa. Therefore, our observations might provide a better understanding of the dynamics of the entropic uncertainty in the Heisenberg spin chain, and thus shed light on quantum precision measurement in the framework of versatile systems, particularly solid states.

First Principles Study of Electronic Band Structure and Structural Stability of Al2C Monolayer and Nanotubes

NASA Astrophysics Data System (ADS)

Pramchu, S.; Jaroenjittichai, A. P.; Laosiritaworn, Y.

2017-09-01

We used density functional theory (DFT) based on generalized gradient approximation (GGA) and hybrid functional (HSE06) to investigate band gap and structural stability of Al2C monolayer and nanotubes. From the results, both GGA and HSE06 band gaps of Al2C monolayer agree well with previously reported data. For the Al2C nanotubes, we found that their band gaps are more sensitive to the size and the chirality than that of the widely studied SiC2 nanotubes, indicating the Al2C nanotubes may have higher band gap tuning capabilities (with varying diameter size and chirality) compared with those of SiC2 nanotubes. We have also discovered a desirable direct band gap in the case of (n,0) nanotubes, although Al2C monolayer band gap is indirect. The calculated strain energy reveals that (n,0) nanotubes constructed by wrapping up Al2C monolayer consume less energy than (0,n) nanotubes. Thus, (n,0) nanotubes is easier to synthesize than (0,n) nanotubes. This discovery of direct band gap in (n,0) Al2C nanotubes and their adjustable band gap suggests them as promising sensitizer for enhancing power conversion efficiency of excitonic solar cells.

Inexact Socio-Dynamic Modeling of Groundwater Contamination Management

NASA Astrophysics Data System (ADS)

Vesselinov, V. V.; Zhang, X.

2015-12-01

Groundwater contamination may alter the behaviors of the public such as adaptation to such a contamination event. On the other hand, social behaviors may affect groundwater contamination and associated risk levels such as through changing ingestion amount of groundwater due to the contamination. Decisions should consider not only the contamination itself, but also social attitudes on such contamination events. Such decisions are inherently associated with uncertainty, such as subjective judgement from decision makers and their implicit knowledge on selection of whether to supply water or reduce the amount of supplied water under the scenario of the contamination. A socio-dynamic model based on the theories of information-gap and fuzzy sets is being developed to address the social behaviors facing the groundwater contamination and applied to a synthetic problem designed based on typical groundwater remediation sites where the effects of social behaviors on decisions are investigated and analyzed. Different uncertainties including deep uncertainty and vague/ambiguous uncertainty are effectively and integrally addressed. The results can provide scientifically-defensible decision supports for groundwater management in face of the contamination.

Integrating uncertainty into public energy research and development decisions

NASA Astrophysics Data System (ADS)

Anadón, Laura Díaz; Baker, Erin; Bosetti, Valentina

2017-05-01

Public energy research and development (R&D) is recognized as a key policy tool for transforming the world's energy system in a cost-effective way. However, managing the uncertainty surrounding technological change is a critical challenge for designing robust and cost-effective energy policies. The design of such policies is particularly important if countries are going to both meet the ambitious greenhouse-gas emissions reductions goals set by the Paris Agreement and achieve the required harmonization with the broader set of objectives dictated by the Sustainable Development Goals. The complexity of informing energy technology policy requires, and is producing, a growing collaboration between different academic disciplines and practitioners. Three analytical components have emerged to support the integration of technological uncertainty into energy policy: expert elicitations, integrated assessment models, and decision frameworks. Here we review efforts to incorporate all three approaches to facilitate public energy R&D decision-making under uncertainty. We highlight emerging insights that are robust across elicitations, models, and frameworks, relating to the allocation of public R&D investments, and identify gaps and challenges that remain.

Global Surface Temperature Change and Uncertainties Since 1861

NASA Technical Reports Server (NTRS)

Shen, Samuel S. P.; Lau, William K. M. (Technical Monitor)

2002-01-01

The objective of this talk is to analyze the warming trend and its uncertainties of the global and hemi-spheric surface temperatures. By the method of statistical optimal averaging scheme, the land surface air temperature and sea surface temperature observational data are used to compute the spatial average annual mean surface air temperature. The optimal averaging method is derived from the minimization of the mean square error between the true and estimated averages and uses the empirical orthogonal functions. The method can accurately estimate the errors of the spatial average due to observational gaps and random measurement errors. In addition, quantified are three independent uncertainty factors: urbanization, change of the in situ observational practices and sea surface temperature data corrections. Based on these uncertainties, the best linear fit to annual global surface temperature gives an increase of 0.61 +/- 0.16 C between 1861 and 2000. This lecture will also touch the topics on the impact of global change on nature and environment. as well as the latest assessment methods for the attributions of global change.

Designing Phononic Crystals with Wide and Robust Band Gaps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Zian; Chen, Yanyu; Yang, Haoxiang

Here, phononic crystals (PnCs) engineered to manipulate and control the propagation of mechanical waves have enabled the design of a range of novel devices, such as waveguides, frequency modulators, and acoustic cloaks, for which wide and robust phononic band gaps are highly preferable. While numerous PnCs have been designed in recent decades, to the best of our knowledge, PnCs that possess simultaneous wide and robust band gaps (to randomness and deformations) have not yet been reported. Here, we demonstrate that by combining the band-gap formation mechanisms of Bragg scattering and local resonances (the latter one is dominating), PnCs with widemore » and robust phononic band gaps can be established. The robustness of the phononic band gaps are then discussed from two aspects: robustness to geometric randomness (manufacture defects) and robustness to deformations (mechanical stimuli). Analytical formulations further predict the optimal design parameters, and an uncertainty analysis quantifies the randomness effect of each designing parameter. Moreover, we show that the deformation robustness originates from a local resonance-dominant mechanism together with the suppression of structural instability. Importantly, the proposed PnCs require only a small number of layers of elements (three unit cells) to obtain broad, robust, and strong attenuation bands, which offer great potential in designing flexible and deformable phononic devices.« less

Designing Phononic Crystals with Wide and Robust Band Gaps

DOE PAGES

Jia, Zian; Chen, Yanyu; Yang, Haoxiang; ...

2018-04-16

Here, phononic crystals (PnCs) engineered to manipulate and control the propagation of mechanical waves have enabled the design of a range of novel devices, such as waveguides, frequency modulators, and acoustic cloaks, for which wide and robust phononic band gaps are highly preferable. While numerous PnCs have been designed in recent decades, to the best of our knowledge, PnCs that possess simultaneous wide and robust band gaps (to randomness and deformations) have not yet been reported. Here, we demonstrate that by combining the band-gap formation mechanisms of Bragg scattering and local resonances (the latter one is dominating), PnCs with widemore » and robust phononic band gaps can be established. The robustness of the phononic band gaps are then discussed from two aspects: robustness to geometric randomness (manufacture defects) and robustness to deformations (mechanical stimuli). Analytical formulations further predict the optimal design parameters, and an uncertainty analysis quantifies the randomness effect of each designing parameter. Moreover, we show that the deformation robustness originates from a local resonance-dominant mechanism together with the suppression of structural instability. Importantly, the proposed PnCs require only a small number of layers of elements (three unit cells) to obtain broad, robust, and strong attenuation bands, which offer great potential in designing flexible and deformable phononic devices.« less

Designing Phononic Crystals with Wide and Robust Band Gaps

NASA Astrophysics Data System (ADS)

Jia, Zian; Chen, Yanyu; Yang, Haoxiang; Wang, Lifeng

2018-04-01

Phononic crystals (PnCs) engineered to manipulate and control the propagation of mechanical waves have enabled the design of a range of novel devices, such as waveguides, frequency modulators, and acoustic cloaks, for which wide and robust phononic band gaps are highly preferable. While numerous PnCs have been designed in recent decades, to the best of our knowledge, PnCs that possess simultaneous wide and robust band gaps (to randomness and deformations) have not yet been reported. Here, we demonstrate that by combining the band-gap formation mechanisms of Bragg scattering and local resonances (the latter one is dominating), PnCs with wide and robust phononic band gaps can be established. The robustness of the phononic band gaps are then discussed from two aspects: robustness to geometric randomness (manufacture defects) and robustness to deformations (mechanical stimuli). Analytical formulations further predict the optimal design parameters, and an uncertainty analysis quantifies the randomness effect of each designing parameter. Moreover, we show that the deformation robustness originates from a local resonance-dominant mechanism together with the suppression of structural instability. Importantly, the proposed PnCs require only a small number of layers of elements (three unit cells) to obtain broad, robust, and strong attenuation bands, which offer great potential in designing flexible and deformable phononic devices.

When, not if: The inescapability of an uncertain future

NASA Astrophysics Data System (ADS)

Lewandowsky, S.; Ballard, T.

2014-12-01

Uncertainty is an inherent feature of most scientific endeavours, and many political decisions must be made in the presence of scientific uncertainty. In the case of climate change, there is evidence that greater scientific uncertainty increases the risk associated with the impact of climate change. Scientific uncertainty thus provides an impetus for cutting emissions rather than delaying action. In contrast to those normative considerations, uncertainty is frequently cited in political and public discourse as a reason to delay mitigation. We examine ways in which this gap between public and scientific understanding of uncertainty can be bridged. In particular, we sought ways to communicate uncertainty in a way that better calibrates people's risk perceptions with the projected impact of climate change. We report two behavioural experiments in which uncertainty about the future was expressed either as outcome uncertainty or temporal uncertainty. The conventional presentation of uncertainty involves uncertainty about an outcome at a given time—for example, the range of possible sea level rise (say 50cm +/- 20cm) by a certain date. An alternative presentation of the same situation presents a certain outcome ("sea levels will rise by 50cm") but places the uncertainty into the time of arrival ("this may occur as early as 2040 or as late as 2080"). We presented participants with a series of statements and graphs indicating projected increases in temperature, sea levels, ocean acidification, and a decrease in artic sea ice. In the uncertain magnitude condition, the statements and graphs reported the upper and lower confidence bounds of the projected magnitude and the mean projected time of arrival. In the uncertain time of arrival condition, they reported the upper and lower confidence bounds of the projected time of arrival and the mean projected magnitude. The results show that when uncertainty was presented as uncertain time of arrival rather than an uncertain outcome, people expressed greater concern about the projected outcomes. In a further experiment involving repeated "games" with a simulated economy, we similarly showed that people allocate more resources to mitigation if there is uncertainty about the timing of an adverse event rather than about the magnitude of its impact.

Frequency Comparison of [Formula: see text] Ion Optical Clocks at PTB and NPL via GPS PPP.

PubMed

Leute, J; Huntemann, N; Lipphardt, B; Tamm, Christian; Nisbet-Jones, P B R; King, S A; Godun, R M; Jones, J M; Margolis, H S; Whibberley, P B; Wallin, A; Merimaa, M; Gill, P; Peik, E

2016-07-01

We used precise point positioning, a well-established GPS carrier-phase frequency transfer method to perform a direct remote comparison of two optical frequency standards based on single laser-cooled [Formula: see text] ions operated at the National Physical Laboratory (NPL), U.K. and the Physikalisch-Technische Bundesanstalt (PTB), Germany. At both institutes, an active hydrogen maser serves as a flywheel oscillator which is connected to a GPS receiver as an external frequency reference and compared simultaneously to a realization of the unperturbed frequency of the (2)S1/2(F=0)-(2)D3/2(F=2) electric quadrupole transition in [Formula: see text] via an optical femtosecond frequency comb. To profit from long coherent GPS-link measurements, we extrapolate the fractional frequency difference over the various data gaps in the optical clock to maser comparisons which introduces maser noise to the frequency comparison but improves the uncertainty from the GPS-link instability. We determined the total statistical uncertainty consisting of the GPS-link uncertainty and the extrapolation uncertainties for several extrapolation schemes. Using the extrapolation scheme with the smallest combined uncertainty, we find a fractional frequency difference [Formula: see text] of -1.3×10(-15) with a combined uncertainty of 1.2×10(-15) for a total measurement time of 67 h. This result is consistent with an agreement of the frequencies realized by both optical clocks and with recent absolute frequency measurements against caesium fountain clocks within the corresponding uncertainties.

A Symbiotic Relationship: The Observe-Orient-Decide-Act (OODA) Loop, Intuition, and Strategic Thought

DTIC Science & Technology

2013-03-01

Incompleteness Theorem (used in mathematics), and Heisenberg’s Uncertainty Principle as it pertains to the mathematical foundations of quantum ...subtlety which normal consciousness cannot even see…”46 It is in our PME system where we can create the time to develop the unconscious realms of the

Human Resource Planning: An Introduction. Report 312.

ERIC Educational Resources Information Center

Reilly, Peter

This report is designed to give readers an introduction to the principles of human resource planning (HRP) and the areas in which it can be used, including those facing today's managers. Chapter 1 outlines why some organizations no longer plan, describes the background of change and uncertainty that discouraged them, and defines HRP. Chapter 2…

Quantum information aspects of noncommutative quantum mechanics

NASA Astrophysics Data System (ADS)

Bertolami, Orfeu; Bernardini, Alex E.; Leal, Pedro

2018-01-01

Some fundamental aspects related with the construction of Robertson-Schrödinger-like uncertainty-principle inequalities are reported in order to provide an overall description of quantumness, separability and nonlocality of quantum systems in the noncommutative phase-space. Some consequences of the deformed noncommutative algebra are also considered in physical systems of interest.

The Heisenberg Uncertainty Principle Demonstrated with An Electron Diffraction Experiment

ERIC Educational Resources Information Center

Matteucci, Giorgio; Ferrari, Loris; Migliori, Andrea

2010-01-01

An experiment analogous to the classical diffraction of light from a circular aperture has been realized with electrons. The results are used to introduce undergraduate students to the wave behaviour of electrons. The diffraction fringes produced by the circular aperture are compared to those predicted by quantum mechanics and are exploited to…

Franchisees in Crisis: Using Action Learning to Self-Organise

ERIC Educational Resources Information Center

O'Donoghue, Carol

2011-01-01

The present article describes the use of action learning by a group of 30 franchisees to organise themselves and work through a period of upheaval and uncertainty when their parent company faced liquidation. Written from the perspective of one of the franchisees who found herself adopting action learning principles to facilitate the group, it…

Quantization of spacetime based on a spacetime interval operator

NASA Astrophysics Data System (ADS)

Chiang, Hsu-Wen; Hu, Yao-Chieh; Chen, Pisin

2016-04-01

Motivated by both concepts of Adler's recent work on utilizing Clifford algebra as the linear line element d s =⟨γμ⟩ d Xμ and the fermionization of the cylindrical worldsheet Polyakov action, we introduce a new type of spacetime quantization that is fully covariant. The theory is based on the reinterpretation of Adler's linear line element as d s =γμ⟨λ γμ⟩ , where λ is the characteristic length of the theory. We name this new operator the "spacetime interval operator" and argue that it can be regarded as a natural extension to the one-forms in the U (s u (2 )) noncommutative geometry. By treating Fourier momentum as the particle momentum, the generalized uncertainty principle of the U (s u (2 )) noncommutative geometry, as an approximation to the generalized uncertainty principle of our theory, is derived and is shown to have a lowest order correction term of the order p2 similar to that of Snyder's. The holography nature of the theory is demonstrated and the predicted fuzziness of the geodesic is shown to be much smaller than conceivable astrophysical bounds.

Risk-based principles for defining and managing water security

PubMed Central

Hall, Jim; Borgomeo, Edoardo

2013-01-01

The concept of water security implies concern about potentially harmful states of coupled human and natural water systems. Those harmful states may be associated with water scarcity (for humans and/or the environment), floods or harmful water quality. The theories and practices of risk analysis and risk management have been developed and elaborated to deal with the uncertain occurrence of harmful events. Yet despite their widespread application in public policy, theories and practices of risk management have well-known limitations, particularly in the context of severe uncertainties and contested values. Here, we seek to explore the boundaries of applicability of risk-based principles as a means of formalizing discussion of water security. Not only do risk concepts have normative appeal, but they also provide an explicit means of addressing the variability that is intrinsic to hydrological, ecological and socio-economic systems. We illustrate the nature of these interconnections with a simulation study, which demonstrates how water resources planning could take more explicit account of epistemic uncertainties, tolerability of risk and the trade-offs in risk among different actors. PMID:24080616

The Species Delimitation Uncertainty Principle

PubMed Central

Adams, Byron J.

2001-01-01

If, as Einstein said, "it is the theory which decides what we can observe," then "the species problem" could be solved by simply improving our theoretical definition of what a species is. However, because delimiting species entails predicting the historical fate of evolutionary lineages, species appear to behave according to the Heisenberg Uncertainty Principle, which states that the most philosophically satisfying definitions of species are the least operational, and as species concepts are modified to become more operational they tend to lose their philosophical integrity. Can species be delimited operationally without losing their philosophical rigor? To mitigate the contingent properties of species that tend to make them difficult for us to delimit, I advocate a set of operations that takes into account the prospective nature of delimiting species. Given the fundamental role of species in studies of evolution and biodiversity, I also suggest that species delimitation proceed within the context of explicit hypothesis testing, like other scientific endeavors. The real challenge is not so much the inherent fallibility of predicting the future but rather adequately sampling and interpreting the evidence available to us in the present. PMID:19265874

First-Principles Study of Impurities in TlBr

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Mao-Hua

2012-01-01

TlBr is a promising semiconductor material for room-temperature radiation detection. Material purification has been the driver for the recent improvement in the TlBr detector performance, mainly reflected by the significant increase in the carrier mobility-lifetime product. This suggests that impurities have significant impact on the carrier transport in TlBr. In this paper, first-principles calculations are used to study the properties of a number of commonly observed impurities in TlBr. The impurity-induced gap states are presented and their effects on the carrier trapping are discussed.

First principles and experimental study of the electronic structure and phase stability of bulk thallium bromide

NASA Astrophysics Data System (ADS)

Smith, Holland M.; Zhou, Yuzhi; Ciampi, Guido; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.; Haller, E. E.; Chrzan, D. C.

2013-08-01

We apply state-of-art first principle calculations to study the polymorphism and electronic structure of three previously reported phases of TlBr. The calculated band structures of NaCl-structure phase and orthorhombic-structure phase have different features than that of commonly observed CsCl-structure phase. We further interpret photoluminescence spectra based on our calculations. Several peaks close to calculated band gap values of the NaCl-structure phase and the orthorhombic-structure phase are found in unpolished TlBr samples.