Bayesian parameter inference for stochastic biochemical network models using particle Markov chain Monte Carlo

PubMed Central

Golightly, Andrew; Wilkinson, Darren J.

2011-01-01

Computational systems biology is concerned with the development of detailed mechanistic models of biological processes. Such models are often stochastic and analytically intractable, containing uncertain parameters that must be estimated from time course data. In this article, we consider the task of inferring the parameters of a stochastic kinetic model defined as a Markov (jump) process. Inference for the parameters of complex nonlinear multivariate stochastic process models is a challenging problem, but we find here that algorithms based on particle Markov chain Monte Carlo turn out to be a very effective computationally intensive approach to the problem. Approximations to the inferential model based on stochastic differential equations (SDEs) are considered, as well as improvements to the inference scheme that exploit the SDE structure. We apply the methodology to a Lotka–Volterra system and a prokaryotic auto-regulatory network. PMID:23226583

Non-fragile observer-based output feedback control for polytopic uncertain system under distributed model predictive control approach

NASA Astrophysics Data System (ADS)

Zhu, Kaiqun; Song, Yan; Zhang, Sunjie; Zhong, Zhaozhun

2017-07-01

In this paper, a non-fragile observer-based output feedback control problem for the polytopic uncertain system under distributed model predictive control (MPC) approach is discussed. By decomposing the global system into some subsystems, the computation complexity is reduced, so it follows that the online designing time can be saved.Moreover, an observer-based output feedback control algorithm is proposed in the framework of distributed MPC to deal with the difficulties in obtaining the states measurements. In this way, the presented observer-based output-feedback MPC strategy is more flexible and applicable in practice than the traditional state-feedback one. What is more, the non-fragility of the controller has been taken into consideration in favour of increasing the robustness of the polytopic uncertain system. After that, a sufficient stability criterion is presented by using Lyapunov-like functional approach, meanwhile, the corresponding control law and the upper bound of the quadratic cost function are derived by solving an optimisation subject to convex constraints. Finally, some simulation examples are employed to show the effectiveness of the method.

Variational Assimilation of Sparse and Uncertain Satellite Data For 1D Saint-Venant River Models

NASA Astrophysics Data System (ADS)

Garambois, P. A.; Brisset, P.; Monnier, J.; Roux, H.

2016-12-01

Profusion of satellites are providing increasingly accurate measurements of continental water cyle, and water bodies variations while in situ observability is declining. The future Surface Water and Ocean Topography (SWOT) mission will provide maps of river surface elevations widths and slopes with an almost global coverage and temporal revisits. This will offer the possibility to address a larger variety of inverse problems in surface hydrology. Data assimilation techniques, that are broadly used in several scientific fields, aim to optimally combine models, system observations and prior information. Variational assimilation consists in iterative minimization of a discrepency measure between model outputs and observations, here for retrieving boundary conditions and parameters of a 1D Saint Venant model. Nevertheless, inferring river discharge and hydraulic parameters thanks to the observation of river surface is not straightforward. This is particularly true in the case of sparse and uncertain observations of flow state variables since they are governed by nonlinear physical processes. This paper investigates the identifiability of hydraulic controls given sparse and uncertain satellite observations of a river. The identifiability of river discharge alone and with roughness is tested for several spatio temporal patterns of river observations, including SWOT like observations. A new 1D Shallow water model with variational data assimilation, within the DassFlow chain is presented as well as postprocessing and observation operator dedicated to the future SWOT and SWOT simulator data. In view to decrease inverse problem dimensionality discharge is represented in a reduced basis. Moreover we introduce an original and reduced parametrization of the flow resistance that can account for various flow regimes along with a cross section design dedicated to remote sensing. We show which discharge temporal frequencies can be identified w.r.t observation ones and at which accuracy. Eventually the important question of the discharge identifiability potential between observation times and depending on the spatio-temporal sampling is adressed with respect to the wave lengths of the hydrological signals.

A Novel Finite-Sum Inequality-Based Method for Robust H∞ Control of Uncertain Discrete-Time Takagi-Sugeno Fuzzy Systems With Interval-Like Time-Varying Delays.

PubMed

Zhang, Xian-Ming; Han, Qing-Long; Ge, Xiaohua

2017-09-22

This paper is concerned with the problem of robust H∞ control of an uncertain discrete-time Takagi-Sugeno fuzzy system with an interval-like time-varying delay. A novel finite-sum inequality-based method is proposed to provide a tighter estimation on the forward difference of certain Lyapunov functional, leading to a less conservative result. First, an auxiliary vector function is used to establish two finite-sum inequalities, which can produce tighter bounds for the finite-sum terms appearing in the forward difference of the Lyapunov functional. Second, a matrix-based quadratic convex approach is employed to equivalently convert the original matrix inequality including a quadratic polynomial on the time-varying delay into two boundary matrix inequalities, which delivers a less conservative bounded real lemma (BRL) for the resultant closed-loop system. Third, based on the BRL, a novel sufficient condition on the existence of suitable robust H∞ fuzzy controllers is derived. Finally, two numerical examples and a computer-simulated truck-trailer system are provided to show the effectiveness of the obtained results.

Using Markov Models of Fault Growth Physics and Environmental Stresses to Optimize Control Actions

NASA Technical Reports Server (NTRS)

Bole, Brian; Goebel, Kai; Vachtsevanos, George

2012-01-01

A generalized Markov chain representation of fault dynamics is presented for the case that available modeling of fault growth physics and future environmental stresses can be represented by two independent stochastic process models. A contrived but representatively challenging example will be presented and analyzed, in which uncertainty in the modeling of fault growth physics is represented by a uniformly distributed dice throwing process, and a discrete random walk is used to represent uncertain modeling of future exogenous loading demands to be placed on the system. A finite horizon dynamic programming algorithm is used to solve for an optimal control policy over a finite time window for the case that stochastic models representing physics of failure and future environmental stresses are known, and the states of both stochastic processes are observable by implemented control routines. The fundamental limitations of optimization performed in the presence of uncertain modeling information are examined by comparing the outcomes obtained from simulations of an optimizing control policy with the outcomes that would be achievable if all modeling uncertainties were removed from the system.

The coordinating contracts of supply chain in a fuzzy decision environment.

PubMed

Sang, Shengju

2016-01-01

The rapid change of the product life cycle is making the parameters of the supply chain models more and more uncertain. Therefore, we consider the coordination mechanisms between one manufacturer and one retailer in a fuzzy decision marking environment, where the parameters of the models can be forecasted and expressed as the triangular fuzzy variables. The centralized decision-making system, two types of supply chain contracts, namely, the revenue sharing contract and the return contract are proposed. To obtain their optimal policies, the fuzzy set theory is adopted to solve these fuzzy models. Finally, three numerical examples are provided to analyze the impacts of the fuzziness of the market demand, retail price and salvage value of the product on the optimal solutions in two contracts. It shows that in order to obtain more fuzzy expected profits the retailer and the manufacturer should seek as low fuzziness of demand, high fuzziness of the retail price and the salvage value as possible in both contracts.

Non-local electron transport through normal and topological ladder-like atomic systems

NASA Astrophysics Data System (ADS)

Kurzyna, Marcin; Kwapiński, Tomasz

2018-05-01

We propose a locally protected ladder-like atomic system (nanoconductor) on a substrate that is insensitive to external perturbations. The system corresponds to coupled atomic chains fabricated on different surfaces. Electron transport properties of such conductors are studied theoretically using the model tight-binding Su-Schriffer-Hegger (SSH) Hamiltonian and Green's function formalism. We have found that the conductance of the system is almost insensitive to single adatoms and oscillates as a function of the side chain length with very large periods. Non-local character of the electron transport was observed also for topological SSH chains where nontrivial end states survive in the presence of disturbances as well as for different substrates. We have found that the careful inspection of the density of states or charge waves can provide the information about the atom energy levels and hopping amplitudes. Moreover, the ladder-like geometry allows one to distinguish between normal and topological zero-energy states. It is important that topological chains do not reveal Friedel oscillations which are observed in non-topological chains.

Energy balance for uranium recovery from seawater

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

Schneider, E.; Lindner, H.

The energy return on investment (EROI) of an energy resource is the ratio of the energy it ultimately produces to the energy used to recover it. EROI is a key viability measure for a new recovery technology, particularly in its early stages of development when financial cost assessment would be premature or highly uncertain. This paper estimates the EROI of uranium recovery from seawater via a braid adsorbent technology. In this paper, the energy cost of obtaining uranium from seawater is assessed by breaking the production chain into three processes: adsorbent production, adsorbent deployment and mooring, and uranium elution andmore » purification. Both direct and embodied energy inputs are considered. Direct energy is the energy used by the processes themselves, while embodied energy is used to fabricate their material, equipment or chemical inputs. If the uranium is used in a once-through fuel cycle, the braid adsorbent technology EROI ranges from 12 to 27, depending on still-uncertain performance and system design parameters. It is highly sensitive to the adsorbent capacity in grams of U captured per kg of adsorbent as well as to potential economies in chemical use. This compares to an EROI of ca. 300 for contemporary terrestrial mining. It is important to note that these figures only consider the mineral extraction step in the fuel cycle. At a reference performance level of 2.76 g U recovered per kg adsorbent immersed, the largest energy consumers are the chemicals used in adsorbent production (63%), anchor chain mooring system fabrication and operations (17%), and unit processes in the adsorbent production step (12%). (authors)« less

Adaptive robust fault tolerant control design for a class of nonlinear uncertain MIMO systems with quantization.

PubMed

Ao, Wei; Song, Yongdong; Wen, Changyun

2017-05-01

In this paper, we investigate the adaptive control problem for a class of nonlinear uncertain MIMO systems with actuator faults and quantization effects. Under some mild conditions, an adaptive robust fault-tolerant control is developed to compensate the affects of uncertainties, actuator failures and errors caused by quantization, and a range of the parameters for these quantizers is established. Furthermore, a Lyapunov-like approach is adopted to demonstrate that the ultimately uniformly bounded output tracking error is guaranteed by the controller, and the signals of the closed-loop system are ensured to be bounded, even in the presence of at most m-q actuators stuck or outage. Finally, numerical simulations are provided to verify and illustrate the effectiveness of the proposed adaptive schemes. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Magnonic analog of relativistic Zitterbewegung in an antiferromagnetic spin chain

NASA Astrophysics Data System (ADS)

Wang, Weiwei; Gu, Chenjie; Zhou, Yan; Fangohr, Hans

2017-07-01

We theoretically investigate the spin-wave (magnon) excitations in a classical antiferromagnetic spin chain with easy-axis anisotropy. We obtain a Dirac-like equation by linearizing the Landau-Lifshitz-Gilbert equation in this antiferromagnetic system, in contrast to the ferromagnetic system in which a Schrödinger-type equation is derived. The Hamiltonian operator in the Dirac-like equation is a pseudo-Hermitian. We compute and demonstrate relativistic Zitterbewegung (trembling motion) in the antiferromagnetic spin chain by measuring the expectation values of the wave-packet position.

Intelligent diagnosis of jaundice with dynamic uncertain causality graph model.

PubMed

Hao, Shao-Rui; Geng, Shi-Chao; Fan, Lin-Xiao; Chen, Jia-Jia; Zhang, Qin; Li, Lan-Juan

2017-05-01

Jaundice is a common and complex clinical symptom potentially occurring in hepatology, general surgery, pediatrics, infectious diseases, gynecology, and obstetrics, and it is fairly difficult to distinguish the cause of jaundice in clinical practice, especially for general practitioners in less developed regions. With collaboration between physicians and artificial intelligence engineers, a comprehensive knowledge base relevant to jaundice was created based on demographic information, symptoms, physical signs, laboratory tests, imaging diagnosis, medical histories, and risk factors. Then a diagnostic modeling and reasoning system using the dynamic uncertain causality graph was proposed. A modularized modeling scheme was presented to reduce the complexity of model construction, providing multiple perspectives and arbitrary granularity for disease causality representations. A "chaining" inference algorithm and weighted logic operation mechanism were employed to guarantee the exactness and efficiency of diagnostic reasoning under situations of incomplete and uncertain information. Moreover, the causal interactions among diseases and symptoms intuitively demonstrated the reasoning process in a graphical manner. Verification was performed using 203 randomly pooled clinical cases, and the accuracy was 99.01% and 84.73%, respectively, with or without laboratory tests in the model. The solutions were more explicable and convincing than common methods such as Bayesian Networks, further increasing the objectivity of clinical decision-making. The promising results indicated that our model could be potentially used in intelligent diagnosis and help decrease public health expenditure.

Critical Code: Software Producibility for Defense

DTIC Science & Technology

2010-01-01

the hazard of a single system failing can often be associated with a much larger aggregate of systems, often spread across a wide geography. The...four words: fault, error, failure, and hazard . These are defined and illustrated in Box 4.2. Information Loss and Traceability As noted above, the...design information when payback is uncertain, diffuse , or most likely far in the future. A goal in formulating incentive models that motivate developer

Analog modeling of Worm-Like Chain molecules using macroscopic beads-on-a-string.

PubMed

Tricard, Simon; Feinstein, Efraim; Shepherd, Robert F; Reches, Meital; Snyder, Phillip W; Bandarage, Dileni C; Prentiss, Mara; Whitesides, George M

2012-07-07

This paper describes an empirical model of polymer dynamics, based on the agitation of millimeter-sized polymeric beads. Although the interactions between the particles in the macroscopic model and those between the monomers of molecular-scale polymers are fundamentally different, both systems follow the Worm-Like Chain theory.

Analysis of Agility Performance of Supply Chain: A Case Study on Indian Automotive Manufacturer

NASA Astrophysics Data System (ADS)

Routroy, S.; Sharma, S.; Bhardwaj, A.

2018-04-01

Manufacturing companies should understand the changing customer needs and expectations, access and defend the competitive pressure, anticipate and manage the uncertain demand and supply chain risk, and implement the appropriate technology to survive and excel in today’s marketplace. Therefore, they are moving away from mass production (i.e. lean supply chain) to one based on fast-responsiveness and flexibility, capitalizing on the rapid advancement in internet technologies and factory-on-demand mode of production (i.e. agile supply chain). It is observed that manufacturing companies in India in general and automotive supply chain in specific are compelled to cultivate supply chain agility for enhancing its performance level on continuous basis and comparing its supply chain agility performance with competitors to survive and sustain in the competitive business environment. Therefore, a methodology is proposed to evaluate the supply chain agility of a manufacturing supply chain and compare its performance level with competitors using Fuzzy Analytic Hierarchy Process and Taguchi Loss Function. A case study is developed and the proposed methodology is applied to Indian automotive supply chain for explaining the salient features of it.

Chain of point-like potentials in Script R3 and infiniteness of the number of bound states

NASA Astrophysics Data System (ADS)

Boitsev, A. A.; Popov, I. Yu; Sokolov, O. V.

2014-10-01

Infinite chain of point-like potentials having the Hamiltonian with infinite number of eigenvalues below the continuous spectrum is constructed. The background of the model is the theory of self-adjoint extensions of symmetric operators in the Hilbert space. The analogous example of the Hamiltonian is obtained for the system of three-dimensional waveguides coupled through point-like windows.

When, not if: the inescapability of an uncertain climate future.

PubMed

Ballard, Timothy; Lewandowsky, Stephan

2015-11-28

Climate change projections necessarily involve uncertainty. Analysis of the physics and mathematics of the climate system reveals that greater uncertainty about future temperature increases is nearly always associated with greater expected damages from climate change. In contrast to those normative constraints, uncertainty is frequently cited in public discourse as a reason to delay mitigative action. This failure to understand the actual implications of uncertainty may incur notable future costs. It is therefore important to communicate uncertainty in a way that improves people's understanding of climate change risks. We examined whether responses to projections were influenced by whether the projection emphasized uncertainty in the outcome or in its time of arrival. We presented participants with statements and graphs indicating projected increases in temperature, sea levels, ocean acidification and a decrease in arctic sea ice. In the uncertain-outcome condition, statements reported the upper and lower confidence bounds of the projected outcome at a fixed time point. In the uncertain time-of-arrival condition, statements reported the upper and lower confidence bounds of the projected time of arrival for a fixed outcome. Results suggested that people perceived the threat as more serious and were more likely to encourage mitigative action in the time-uncertain condition than in the outcome-uncertain condition. This finding has implications for effectively communicating the climate change risks to policy-makers and the general public. © 2015 The Author(s).

Immunoglobulin derived depositions in the nervous system: novel mass spectrometry application for protein characterization in formalin-fixed tissues.

PubMed

Rodriguez, Fausto J; Gamez, Jeffrey D; Vrana, Julie A; Theis, Jason D; Giannini, Caterina; Scheithauer, Bernd W; Parisi, Joseph E; Lucchinetti, Claudia F; Pendlebury, William W; Bergen, H Robert; Dogan, Ahmet

2008-10-01

Proteinaceous deposits are occasionally encountered in surgically obtained biopsies of the nervous system. Some of these are amyloidomas, although the precise nature of other cases remains uncertain. We studied 13 cases of proteinaceous aggregates in clinical specimens of the nervous system. Proteins contained within laser microdissected areas of interest were identified from tryptic peptide sequences by liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS). Immunohistochemical studies for immunoglobulin heavy and light chains and amyloidogenic proteins were performed in all cases. Histologically, the cases were classified into three groups: 'proteinaceous deposit not otherwise specified' (PDNOS) (n=6), amyloidoma (n=5), or 'intracellular crystals' (n=2). LC-MS/MS demonstrated the presence of lambda, but not kappa, light chain as well as serum amyloid P in all amyloidomas. lambda-Light-chain immunostaining was noted in amyloid (n=5), although demonstrable monotypic lymphoplasmacytic cells were seen in only one case. Conversely, in PDNOS kappa, but not lambda, was evident in five cases, both light chains being present in a single case. In three cases of PDNOS, a low-grade B-cell lymphoma consistent with marginal zone lymphoma was present in the brain specimen (n=2) or spleen (n=1). Lastly, in the 'intracellular crystals' group, the crystals were present within CD68+ macrophages in one case wherein kappa-light chain was found by LC-MS/MS only; the pathology was consistent with crystal-storing histiocytosis. In the second case, the crystals contained immunoglobulin G within CD138+ plasma cells. Our results show that proteinaceous deposits in the nervous system contain immunoglobulin components and LC-MS/MS accurately identifies the content of these deposits in clinical biopsy specimens. LC-MS/MS represents a novel application for characterization of these deposits and is of diagnostic utility in addition to standard immunohistochemical analyses.

Probabilistic Parameter Uncertainty Analysis of Single Input Single Output Control Systems

NASA Technical Reports Server (NTRS)

Smith, Brett A.; Kenny, Sean P.; Crespo, Luis G.

2005-01-01

The current standards for handling uncertainty in control systems use interval bounds for definition of the uncertain parameters. This approach gives no information about the likelihood of system performance, but simply gives the response bounds. When used in design, current methods of m-analysis and can lead to overly conservative controller design. With these methods, worst case conditions are weighted equally with the most likely conditions. This research explores a unique approach for probabilistic analysis of control systems. Current reliability methods are examined showing the strong areas of each in handling probability. A hybrid method is developed using these reliability tools for efficiently propagating probabilistic uncertainty through classical control analysis problems. The method developed is applied to classical response analysis as well as analysis methods that explore the effects of the uncertain parameters on stability and performance metrics. The benefits of using this hybrid approach for calculating the mean and variance of responses cumulative distribution functions are shown. Results of the probabilistic analysis of a missile pitch control system, and a non-collocated mass spring system, show the added information provided by this hybrid analysis.

Analysis and Reduction of Complex Networks Under Uncertainty.

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

Ghanem, Roger G

2014-07-31

This effort was a collaboration with Youssef Marzouk of MIT, Omar Knio of Duke University (at the time at Johns Hopkins University) and Habib Najm of Sandia National Laboratories. The objective of this effort was to develop the mathematical and algorithmic capacity to analyze complex networks under uncertainty. Of interest were chemical reaction networks and smart grid networks. The statements of work for USC focused on the development of stochastic reduced models for uncertain networks. The USC team was led by Professor Roger Ghanem and consisted of one graduate student and a postdoc. The contributions completed by the USC teammore » consisted of 1) methodology and algorithms to address the eigenvalue problem, a problem of significance in the stability of networks under stochastic perturbations, 2) methodology and algorithms to characterize probability measures on graph structures with random flows. This is an important problem in characterizing random demand (encountered in smart grid) and random degradation (encountered in infrastructure systems), as well as modeling errors in Markov Chains (with ubiquitous relevance !). 3) methodology and algorithms for treating inequalities in uncertain systems. This is an important problem in the context of models for material failure and network flows under uncertainty where conditions of failure or flow are described in the form of inequalities between the state variables.« less

Early time evolution of a localized nonlinear excitation in the β-FPUT chain

NASA Astrophysics Data System (ADS)

Kashyap, Rahul; Westley, Alexandra; Datta, Amitava; Sen, Surajit

2017-04-01

We present the detailed dynamics of the particles in the β-Fermi-Pasta-Ulam-Tsingou (FPUT) chain after the initiation of a localized nonlinear excitation (LNE) by squeezing a central bond in the monodispersed chain at time t = 0 while all other particles remain in their original relaxed positions. In the absence of phonons in the system, the LNE appears to initiate its relaxation process by symmetrically emitting two very weak solitary waves. The next stage involves the spreading of the LNE and the formation of nonsolitary wave-like objects to broaden the excitation region until a stage is reached when many weak solitary wave-like objects can be emitted as the system begins its journey to quasi-equilibrium and then to equilibrium. In addition to being of fundamental interest, these systems may be realized using cantilever systems and could well hold the key to constructing the next generation of broadband energy harvesting systems.

Statistical Ring Catenation under Thermodynamic Control: Should the Jacobson-Stockmayer Cyclization Theory Take into Account Catenane Formation?

PubMed

Di Stefano, Stefano; Ercolani, Gianfranco

2017-01-26

An extension of the Jacobson-Stockmayer theory is presented to include the reversible formation of [2]catenanes in a ring-chain system under thermodynamic control. The extended theory is based on the molar catenation constant, measuring the ease of catenation of two ring oligomers, whose expression was obtained in a previous work. Two scenarios have been considered: that of "thick" (hydrocarbon-like) chains and that of "thin" (DNA-like) chains. In the case of "thick" chains, the formation of catenanes can be neglected, unless in the unlikely case of a very large value of the equilibrium constant for linear propagation (K ≈ 10 8 mol -1 L, or larger). For K tending to infinity, the system becomes a chain-free system where only ring-catenane equilibria occur. Under this condition, there is a critical concentration below which only rings are present at equilibrium and above which the ring fraction remains constant, and the excess monomer is converted only into catenanes. In the case of "thin" chains, the formation of catenanes cannot be neglected even for values of K as low as 10 2 mol -1 L, thus justifying the use of the extended theory.

A stochastic inventory management model for a dual sourcing supply chain with disruptions

NASA Astrophysics Data System (ADS)

Iakovou, Eleftherios; Vlachos, Dimitrios; Xanthopoulos, Anastasios

2010-03-01

As companies continue to globalise their operations and outsource significant portion of their value chain activities, they often end up relying heavily on order replenishments from distant suppliers. The explosion in long-distance sourcing is exposing supply chains and shareholder value at ever increasing operational and disruption risks. It is well established, both in academia and in real-world business environments, that resource flexibility is an effective method for hedging against supply chain disruption risks. In this contextual framework, we propose a single period stochastic inventory decision-making model that could be employed for capturing the trade-off between inventory policies and disruption risks for an unreliable dual sourcing supply network for both the capacitated and uncapacitated cases. Through the developed model, we obtain some important managerial insights and evaluate the merit of contingency strategies in managing uncertain supply chains.

Single step, pH induced gold nanoparticle chain formation in lecithin/water system.

PubMed

Sharma, Damyanti

2013-07-01

Gold nanoparticle (AuNP) chains have been formed by a single step method in a lecithin/water system where lecithin itself plays the role of a reductant and a template for AuNP chain formation. Two preparative strategies were explored: (1) evaporating lecithin solution with aqueous gold chloride (HAuCl4) at different pHs and (2) dispersing lecithin vesicles in aqueous HAuCl4 solutions of various pHs in the range of 2.5-11.3. In method 1, at initial pH 2.5, 20-50 nm AuNPs are found attached to lecithin vesicles. When pH is raised to 5.5 there are no vesicles present and 20 nm monodisperse particles are found aggregating. Chain formation of fine nanoparticles (3-5 nm) is observed from neutral to basic pH, between 6.5-10.3 The chains formed are hundreds of nanometers to micrometer long and are usually 2-3 nanoparticles wide. On further increasing pH to 11.3, particles form disk-like or raft-like structures. When method (ii) was used a little chain formation was observed. Most of the nanoparticles formed were found either sitting together as raft like structures or scattered on lecithin structures. Copyright © 2013 Elsevier B.V. All rights reserved.

Scheduling in the Face of Uncertain Resource Consumption and Utility

NASA Technical Reports Server (NTRS)

Frank, Jeremy; Dearden, Richard

2003-01-01

We discuss the problem of scheduling tasks that consume uncertain amounts of a resource with known capacity and where the tasks have uncertain utility. In these circumstances, we would like to find schedules that exceed a lower bound on the expected utility when executed. We show that the problems are NP- complete, and present some results that characterize the behavior of some simple heuristics over a variety of problem classes.

Active disturbance rejection control based robust output feedback autopilot design for airbreathing hypersonic vehicles.

PubMed

Tian, Jiayi; Zhang, Shifeng; Zhang, Yinhui; Li, Tong

2018-03-01

Since motion control plant (y (n) =f(⋅)+d) was repeatedly used to exemplify how active disturbance rejection control (ADRC) works when it was proposed, the integral chain system subject to matched disturbances is always regarded as a canonical form and even misconstrued as the only form that ADRC is applicable to. In this paper, a systematic approach is first presented to apply ADRC to a generic nonlinear uncertain system with mismatched disturbances and a robust output feedback autopilot for an airbreathing hypersonic vehicle (AHV) is devised based on that. The key idea is to employ the feedback linearization (FL) and equivalent input disturbance (EID) technique to decouple nonlinear uncertain system into several subsystems in canonical form, thus it would be much easy to directly design classical/improved linear/nonlinear ADRC controller for each subsystem. It is noticed that all disturbances are taken into account when implementing FL rather than just omitting that in previous research, which greatly enhances controllers' robustness against external disturbances. For autopilot design, ADRC strategy enables precise tracking for velocity and altitude reference command in the presence of severe parametric perturbations and atmospheric disturbances only using measurable output information. Bounded-input-bounded-output (BIBO) stable is analyzed for closed-loop system. To illustrate the feasibility and superiority of this novel design, a series of comparative simulations with some prominent and representative methods are carried out on a benchmark longitudinal AHV model. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

On the uncertain nature of the core of α Cen A

NASA Astrophysics Data System (ADS)

Bazot, M.; Christensen-Dalsgaard, J.; Gizon, L.; Benomar, O.

2016-08-01

High-quality astrometric, spectroscopic, interferometric and, importantly, asteroseismic observations are available for α Cen A, which is the closest binary star system to earth. Taking all these constraints into account, we study the internal structure of the star by means of theoretical modelling. Using the Aarhus STellar Evolution Code (ASTEC) and the tools of Computational Bayesian Statistics, in particular a Markov chain Monte Carlo algorithm, we perform statistical inferences for the physical characteristics of the star. We find that α Cen A has a probability of approximately 40 per cent of having a convective core. This probability drops to few per cent if one considers reduced rates for the 14N(p,γ)15O reaction. These convective cores have fractional radii less than 8 per cent when overshoot is neglected. Including overshooting also leads to the possibility of a convective core mostly sustained by the ppII chain energy output. We finally show that roughly 30 per cent of the stellar models describing α Cen A are in the subgiant regime.

Robust adaptive controller design for a class of uncertain nonlinear systems using online T-S fuzzy-neural modeling approach.

PubMed

Chien, Yi-Hsing; Wang, Wei-Yen; Leu, Yih-Guang; Lee, Tsu-Tian

2011-04-01

This paper proposes a novel method of online modeling and control via the Takagi-Sugeno (T-S) fuzzy-neural model for a class of uncertain nonlinear systems with some kinds of outputs. Although studies about adaptive T-S fuzzy-neural controllers have been made on some nonaffine nonlinear systems, little is known about the more complicated uncertain nonlinear systems. Because the nonlinear functions of the systems are uncertain, traditional T-S fuzzy control methods can model and control them only with great difficulty, if at all. Instead of modeling these uncertain functions directly, we propose that a T-S fuzzy-neural model approximates a so-called virtual linearized system (VLS) of the system, which includes modeling errors and external disturbances. We also propose an online identification algorithm for the VLS and put significant emphasis on robust tracking controller design using an adaptive scheme for the uncertain systems. Moreover, the stability of the closed-loop systems is proven by using strictly positive real Lyapunov theory. The proposed overall scheme guarantees that the outputs of the closed-loop systems asymptotically track the desired output trajectories. To illustrate the effectiveness and applicability of the proposed method, simulation results are given in this paper.

Adaptive route choice modeling in uncertain traffic networks with real-time information.

DOT National Transportation Integrated Search

2013-03-01

The objective of the research is to study travelers' route choice behavior in uncertain traffic networks : with real-time information. The research is motivated by two observations of the traffic system: 1) : the system is inherently uncertain with r...

Skin-like biosensor system via electrochemical channels for noninvasive blood glucose monitoring.

PubMed

Chen, Yihao; Lu, Siyuan; Zhang, Shasha; Li, Yan; Qu, Zhe; Chen, Ying; Lu, Bingwei; Wang, Xinyan; Feng, Xue

2017-12-01

Currently, noninvasive glucose monitoring is not widely appreciated because of its uncertain measurement accuracy, weak blood glucose correlation, and inability to detect hyperglycemia/hypoglycemia during sleep. We present a strategy to design and fabricate a skin-like biosensor system for noninvasive, in situ, and highly accurate intravascular blood glucose monitoring. The system integrates an ultrathin skin-like biosensor with paper battery-powered electrochemical twin channels (ETCs). The designed subcutaneous ETCs drive intravascular blood glucose out of the vessel and transport it to the skin surface. The ultrathin (~3 μm) nanostructured biosensor, with high sensitivity (130.4 μA/mM), fully absorbs and measures the glucose, owing to its extreme conformability. We conducted in vivo human clinical trials. The noninvasive measurement results for intravascular blood glucose showed a high correlation (>0.9) with clinically measured blood glucose levels. The system opens up new prospects for clinical-grade noninvasive continuous glucose monitoring.

Skin-like biosensor system via electrochemical channels for noninvasive blood glucose monitoring

PubMed Central

Chen, Yihao; Lu, Siyuan; Zhang, Shasha; Li, Yan; Qu, Zhe; Chen, Ying; Lu, Bingwei; Wang, Xinyan; Feng, Xue

2017-01-01

Currently, noninvasive glucose monitoring is not widely appreciated because of its uncertain measurement accuracy, weak blood glucose correlation, and inability to detect hyperglycemia/hypoglycemia during sleep. We present a strategy to design and fabricate a skin-like biosensor system for noninvasive, in situ, and highly accurate intravascular blood glucose monitoring. The system integrates an ultrathin skin-like biosensor with paper battery–powered electrochemical twin channels (ETCs). The designed subcutaneous ETCs drive intravascular blood glucose out of the vessel and transport it to the skin surface. The ultrathin (~3 μm) nanostructured biosensor, with high sensitivity (130.4 μA/mM), fully absorbs and measures the glucose, owing to its extreme conformability. We conducted in vivo human clinical trials. The noninvasive measurement results for intravascular blood glucose showed a high correlation (>0.9) with clinically measured blood glucose levels. The system opens up new prospects for clinical-grade noninvasive continuous glucose monitoring. PMID:29279864

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

Xing, Kunyue; Chatterjee, Sabornie; Saito, Tomonori

Dielectric spectroscopy, rheology, and differential scanning calorimetry were employed to study the effect of chain-end hydrogen bonding on the dynamics of hydroxylterminated polydimethylsiloxane. We demonstrate that hydrogen bonding has a strong influence on both segmental and slower dynamics in the systems with low molecular weights. In particular, the decrease in the chain length leads to an increase of the glass transition temperature, viscosity, and fragility index, at variance with the usual behavior of nonassociating polymers. The supramolecular association of hydroxylterminated chains leads to the emergence in dielectric and mechanical relaxation spectra of the so-called Debye process traditionally observed in monohydroxymore » alcohols. Our analysis suggests that the hydroxyl-terminated PDMS oligomers may associate in brush-like or chain-like structures, depending on the size of their covalent chains. Finally, the effective length of the linear-associated chains was estimated from the rheological measurements.« less

Closed loop supply chain network design with fuzzy tactical decisions

NASA Astrophysics Data System (ADS)

Sherafati, Mahtab; Bashiri, Mahdi

2016-09-01

One of the most strategic and the most significant decisions in supply chain management is reconfiguration of the structure and design of the supply chain network. In this paper, a closed loop supply chain network design model is presented to select the best tactical and strategic decision levels simultaneously considering the appropriate transportation mode in activated links. The strategic decisions are made for a long term; thus, it is more satisfactory and more appropriate when the decision variables are considered uncertain and fuzzy, because it is more flexible and near to the real world. This paper is the first research which considers fuzzy decision variables in the supply chain network design model. Moreover, in this study a new fuzzy optimization approach is proposed to solve a supply chain network design problem with fuzzy tactical decision variables. Finally, the proposed approach and model are verified using several numerical examples. The comparison of the results with other existing approaches confirms efficiency of the proposed approach. Moreover the results confirms that by considering the vagueness of tactical decisions some properties of the supply chain network will be improved.

A functional approach to emotion in autonomous systems.

PubMed

Sanz, Ricardo; Hernández, Carlos; Gómez, Jaime; Hernando, Adolfo

2010-01-01

The construction of fully effective systems seems to pass through the proper exploitation of goal-centric self-evaluative capabilities that let the system teleologically self-manage. Emotions seem to provide this kind of functionality to biological systems and hence the interest in emotion for function sustainment in artificial systems performing in changing and uncertain environments; far beyond the media hullabaloo of displaying human-like emotion-laden faces in robots. This chapter provides a brief analysis of the scientific theories of emotion and presents an engineering approach for developing technology for robust autonomy by implementing functionality inspired in that of biological emotions.

Advantages of a distant cellulase catalytic base.

PubMed

Burgin, Tucker; Ståhlberg, Jerry; Mayes, Heather B

2018-03-30

The inverting glycoside hydrolase Trichoderma reesei ( Hypocrea jecorina ) Cel6A is a promising candidate for protein engineering for more economical production of biofuels. Until recently, its catalytic mechanism had been uncertain: The best candidate residue to serve as a catalytic base, Asp-175, is farther from the glycosidic cleavage site than in other glycoside hydrolase enzymes. Recent unbiased transition path sampling simulations revealed the hydrolytic mechanism for this more distant base, employing a water wire; however, it is not clear why the enzyme employs a more distant catalytic base, a highly conserved feature among homologs across different kingdoms. In this work, we describe molecular dynamics simulations designed to uncover how a base with a longer side chain, as in a D175E mutant, affects procession and active site alignment in the Michaelis complex. We show that the hydrogen bond network is tuned to the shorter aspartate side chain, and that a longer glutamate side chain inhibits procession as well as being less likely to adopt a catalytically productive conformation. Furthermore, we draw comparisons between the active site in Trichoderma reesei Cel6A and another inverting, processive cellulase to deduce the contribution of the water wire to the overall enzyme function, revealing that the more distant catalytic base enhances product release. Our results can inform efforts in the study and design of enzymes by demonstrating how counterintuitive sacrifices in chemical reactivity can have worthwhile benefits for other steps in the catalytic cycle. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Autonomous Landing and Smart Anchoring for In-Situ Exploration of Small Bodies

NASA Technical Reports Server (NTRS)

Ghavimi, Ali R.; Serricchio, Frederick; Hadaegh, Fred Y.; Dolgin, Ben

2000-01-01

Future NASA missions include in-situ scientific explorations of small interplanetary objects like comets and asteroids. Sample acquisition systems are envisioned to operate directly from the landers that are anchored to the surface. Landing and anchoring proves to be challenging in the absence of an attitude control system and in the presence of nearly zero-gravity environments with uncertain surface terrain and unknown mechanical properties. This paper presents recent advancements in developing a novel landing and anchoring control system for the exploration of small bodies.

Schools with Special Needs Students Connect with Parents in a Crisis

ERIC Educational Resources Information Center

Cancro, Lorraine

2009-01-01

Long gone are the days of parent phone chains. Today, faster communications and instant alerts for any situation can empower school administrators to handle difficult events and put parent concerns at ease with better prepared school safety management. Keeping students safe and families informed in an increasingly uncertain world is a top priority…

Impact of hydrogen bonding on dynamics of hydroxyl-terminated polydimethylsiloxane

DOE PAGES

Xing, Kunyue; Chatterjee, Sabornie; Saito, Tomonori; ...

2016-04-06

Dielectric spectroscopy, rheology, and differential scanning calorimetry were employed to study the effect of chain-end hydrogen bonding on the dynamics of hydroxylterminated polydimethylsiloxane. We demonstrate that hydrogen bonding has a strong influence on both segmental and slower dynamics in the systems with low molecular weights. In particular, the decrease in the chain length leads to an increase of the glass transition temperature, viscosity, and fragility index, at variance with the usual behavior of nonassociating polymers. The supramolecular association of hydroxylterminated chains leads to the emergence in dielectric and mechanical relaxation spectra of the so-called Debye process traditionally observed in monohydroxymore » alcohols. Our analysis suggests that the hydroxyl-terminated PDMS oligomers may associate in brush-like or chain-like structures, depending on the size of their covalent chains. Finally, the effective length of the linear-associated chains was estimated from the rheological measurements.« less

A linear quadratic regulator approach to the stabilization of uncertain linear systems

NASA Technical Reports Server (NTRS)

Shieh, L. S.; Sunkel, J. W.; Wang, Y. J.

1990-01-01

This paper presents a linear quadratic regulator approach to the stabilization of uncertain linear systems. The uncertain systems under consideration are described by state equations with the presence of time-varying unknown-but-bounded uncertainty matrices. The method is based on linear quadratic regulator (LQR) theory and Liapunov stability theory. The robust stabilizing control law for a given uncertain system can be easily constructed from the symmetric positive-definite solution of the associated augmented Riccati equation. The proposed approach can be applied to matched and/or mismatched systems with uncertainty matrices in which only their matrix norms are bounded by some prescribed values and/or their entries are bounded by some prescribed constraint sets. Several numerical examples are presented to illustrate the results.

Chain representations of Open Quantum Systems and Lieb-Robinson like bounds for the dynamics

NASA Astrophysics Data System (ADS)

Woods, Mischa

2013-03-01

This talk is concerned with the mapping of the Hamiltonian of open quantum systems onto chain representations, which forms the basis for a rigorous theory of the interaction of a system with its environment. This mapping progresses as an interaction which gives rise to a sequence of residual spectral densities of the system. The rigorous mathematical properties of this mapping have been unknown so far. Here we develop the theory of secondary measures to derive an analytic, expression for the sequence solely in terms of the initial measure and its associated orthogonal polynomials of the first and second kind. These mappings can be thought of as taking a highly nonlocal Hamiltonian to a local Hamiltonian. In the latter, a Lieb-Robinson like bound for the dynamics of the open quantum system makes sense. We develop analytical bounds on the error to observables of the system as a function of time when the semi-infinite chain in truncated at some finite length. The fact that this is possible shows that there is a finite ``Speed of sound'' in these chain representations. This has many implications of the simulatability of open quantum systems of this type and demonstrates that a truncated chain can faithfully reproduce the dynamics at shorter times. These results make a significant and mathematically rigorous contribution to the understanding of the theory of open quantum systems; and pave the way towards the efficient simulation of these systems, which within the standard methods, is often an intractable problem. EPSRC CDT in Controlled Quantum Dynamics, EU STREP project and Alexander von Humboldt Foundation

Hypernetted-chain-like closure of Ornstein-Zernike equation in multibody dissipative particle dynamics

NASA Astrophysics Data System (ADS)

Mo, Chao-jie; Qin, Li-zi; Yang, Li-jun

2017-10-01

We have derived a hypernetted-chain-like (HNC-like) approximate closure of the Ornstein-Zernike equation for multibody dissipative particle dynamics (MDPD) system in which the classic closures are not directly practicable. We first point out that the Percus's method is applicable to MDPD system in which particles interact with a density-dependent potential. And then an HNC-like closure is derived using Percus's idea and the saddle-point approximation of particle free energy. This HNC-like closure is compared with results of previous researchers, and in many cases, it demonstrates better agreement with computer simulation results. The HNC-like closure is used to predict the cluster crystallization in MDPD. We determine whether the cluster crystallization will happen in a system utilizing the widely applicable Hansen-Verlet freezing criterion and by observing the radial distribution function. The conclusions drawn from the results of the HNC-like closure are in agreement with computer simulation results. We evaluate different weight functions to determine whether they are prone to cluster crystallization. A new effective density-dependent pairwise potential is also proposed to help to explain the tendency to cluster crystallization of MDPD systems.

The Lγ Phase of Pulmonary Surfactant.

PubMed

Kumar, Kamlesh; Chavarha, Mariya; Loney, Ryan W; Weiss, Thomas M; Rananavare, Shankar B; Hall, Stephen B

2018-06-05

To determine how different components affect the structure of pulmonary surfactant, we measured X-ray scattering by samples derived from calf surfactant. The surfactant phospholipids demonstrated the essential characteristics of the L γ phase: a unit cell with a lattice constant appropriate for two bilayers, and crystalline chains detected by wide-angle X-ray scattering (WAXS). The electron density profile, obtained from scattering by oriented films at different relative humidities (70-97%), showed that the two bilayers, arranged as mirror images, each contain two distinct leaflets with different thicknesses and profiles. The detailed structures suggest one ordered leaflet that would contain crystalline chains and one disordered monolayer likely to contain the anionic compounds, which constitute ∼10% of the surfactant phospholipids. The spacing and temperature dependence detected by WAXS fit with an ordered leaflet composed of dipalmitoyl phosphatidylcholine. Physiological levels of cholesterol had no effect on this structure. Removing the anionic phospholipids prevented formation of the L γ phase. The cationic surfactant proteins inhibited L γ structures, but at levels unlikely related to charge. Because the L γ phase, if arranged properly, could produce a self-assembled ordered interfacial monolayer, the structure could have important functional consequences. Physiological levels of the proteins, however, inhibit formation of the L γ structures at high relative humidities, making their physiological significance uncertain.

Multivariate Analysis of Mixed Lipid Aggregate Phase Transitions Monitored Using Raman Spectroscopy.

PubMed

Neal, Sharon L

2018-01-01

The phase behavior of aqueous 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC)/1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) mixtures between 8.0 ℃ and 41.0 ℃ were monitored using Raman spectroscopy. Temperature-dependent Raman matrices were assembled from series of spectra and subjected to multivariate analysis. The consensus of pseudo-rank estimation results is that seven to eight components account for the temperature-dependent changes observed in the spectra. The spectra and temperature response profiles of the mixture components were resolved by applying a variant of the non-negative matrix factorization (NMF) algorithm described by Lee and Seung (1999). The rotational ambiguity of the data matrix was reduced by augmenting the original temperature-dependent spectral matrix with its cumulative counterpart, i.e., the matrix formed by successive integration of the spectra across the temperature index (columns). Successive rounds of constrained NMF were used to isolate component spectra from a significant fluorescence background. Five major components exhibiting varying degrees of gel and liquid crystalline lipid character were resolved. Hydrogen-bonded water networks exhibiting varying degrees of organization are associated with the lipid components. Spectral parameters were computed to compare the chain conformation, packing, and hydration indicated by the resolved spectra. Based on spectral features and relative amounts of the components observed, four components reflect long chain lipid response. The fifth component could reflect the response of the short chain lipid, DHPC, but there were no definitive spectral features confirming this assignment. A minor component of uncertain assignment that exhibits a striking response to the DMPC pre-transition and chain melting transition also was recovered. While none of the spectra resolved exhibit features unequivocally attributable to a specific aggregate morphology or step in the gelation process, the results are consistent with the evolution of mixed phase bicelles (nanodisks) and small amounts of worm-like DMPC/DHPC aggregates, and perhaps DHPC micelles, at low temperature to suspensions of branched and entangled worm-like aggregates above the DMPC gel phase transition and perforated multi-lamellar aggregates at high temperature.

Finite-time synchronization of uncertain coupled switched neural networks under asynchronous switching.

PubMed

Wu, Yuanyuan; Cao, Jinde; Li, Qingbo; Alsaedi, Ahmed; Alsaadi, Fuad E

2017-01-01

This paper deals with the finite-time synchronization problem for a class of uncertain coupled switched neural networks under asynchronous switching. By constructing appropriate Lyapunov-like functionals and using the average dwell time technique, some sufficient criteria are derived to guarantee the finite-time synchronization of considered uncertain coupled switched neural networks. Meanwhile, the asynchronous switching feedback controller is designed to finite-time synchronize the concerned networks. Finally, two numerical examples are introduced to show the validity of the main results. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimal Decision Making in a Class of Uncertain Systems Based on Uncertain Variables

NASA Astrophysics Data System (ADS)

Bubnicki, Z.

2006-06-01

The paper is concerned with a class of uncertain systems described by relational knowledge representations with unknown parameters which are assumed to be values of uncertain variables characterized by a user in the form of certainty distributions. The first part presents the basic optimization problem consisting in finding the decision maximizing the certainty index that the requirement given by a user is satisfied. The main part is devoted to the description of the optimization problem with the given certainty threshold. It is shown how the approach presented in the paper may be applied to some problems for anticipatory systems.

DSB Task Force on Cyber Supply Chain

DTIC Science & Technology

2017-04-01

seeking to exploit a maliciously inserted vulnerability must execute each step in the kill chain:  Intelligence and planning: gathering...are intended to take a comprehensive approach in considering all aspects of system security, including cybersecurity , and address initial steps to...specific integrated circuits (ASICs). That need is likely to grow for systems that support intelligent or autonomous capabilities. The current

Stackelberg Game of Buyback Policy in Supply Chain with a Risk-Averse Retailer and a Risk-Averse Supplier Based on CVaR

PubMed Central

Zhou, Yanju; Chen, Qian; Chen, Xiaohong; Wang, Zongrun

2014-01-01

This paper considers a decentralized supply chain in which a single supplier sells a perishable product to a single retailer facing uncertain demand. We assume that the supplier and the retailer are both risk averse and utilize Conditional Value at Risk (CVaR), a risk measure method which is popularized in financial risk management, to estimate their risk attitude. We establish a buyback policy model based on Stackelberg game theory under considering supply chain members' risk preference and get the expressions of the supplier's optimal repurchase price and the retailer's optimal order quantity which are compared with those under risk neutral case. Finally, a numerical example is applied to simulate that model and prove related conclusions. PMID:25247605

Stackelberg game of buyback policy in supply chain with a risk-averse retailer and a risk-averse supplier based on CVaR.

PubMed

Zhou, Yanju; Chen, Qian; Chen, Xiaohong; Wang, Zongrun

2014-01-01

This paper considers a decentralized supply chain in which a single supplier sells a perishable product to a single retailer facing uncertain demand. We assume that the supplier and the retailer are both risk averse and utilize Conditional Value at Risk (CVaR), a risk measure method which is popularized in financial risk management, to estimate their risk attitude. We establish a buyback policy model based on Stackelberg game theory under considering supply chain members' risk preference and get the expressions of the supplier's optimal repurchase price and the retailer's optimal order quantity which are compared with those under risk neutral case. Finally, a numerical example is applied to simulate that model and prove related conclusions.

[Quality of medicines in least developed countries].

PubMed

Videau, J Y

2006-12-01

Due to worsening economic conditions and poor enforcement of existing pharmaceutical and customs regulations, third world countries are faced with a growing threat from counterfeit and substandard medicines. With the expansion of illicit markets in urban areas, the sales of medicines of uncertain quality and origin are increasing. Most victims of this illicit trade are among the world's poorest populations that cannot afford to buy quality drugs through private-sector distribution channels. National pharmaceutical programs promoting universal access to essential generic medicines at reasonable cost are the key to curbing this problem. A system based on strict, rational pharmaceutical purchasing and distribution policies with quality assurance at every level of the supply chain is needed to guarantee that patients receive safe effective high quality healthcare products.

Diversification in the Supply Chain of (99)Mo Ensures a Future for (99m)Tc.

PubMed

Cutler, Cathy S; Schwarz, Sally W

2014-07-01

The uncertain availability of (99m)Tc has become a concern for nuclear medicine departments across the globe. An issue for the United States is that currently it is dependent on a supply of (99m)Tc (from (99)Mo) that is derived solely by production outside the United States. Since the United States uses half the world's (99)Mo production, the U.S. (99)Mo supply chain would be greatly enhanced if a producer were located within the United States. The fragility of the old (99)Mo supply chain is being addressed as new facilities are constructed and new processes are developed to produce (99)Mo without highly enriched uranium. The conversion to low-enriched uranium is necessary to minimize the potential misuse of highly enriched uranium in the world for nonpeaceful means. New production facilities, new methods for the production of (99)Mo, and a new generator elution system for the supply of (99m)Tc are currently being pursued. The progress made in all these areas will be discussed, as they all highlight the need to embrace diversity to ensure that we have a robust and reliable supply of (99m)Tc in the future. © 2014 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Analysis of Implicit Uncertain Systems. Part 1: Theoretical Framework

DTIC Science & Technology

1994-12-07

Analysis of Implicit Uncertain Systems Part I: Theoretical Framework Fernando Paganini * John Doyle 1 December 7, 1994 Abst rac t This paper...Analysis of Implicit Uncertain Systems Part I: Theoretical Framework 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...model and a number of constraints relevant to the analysis problem under consideration. In Part I of this paper we propose a theoretical framework which

Research of Uncertainty Reasoning in Pineapple Disease Identification System

NASA Astrophysics Data System (ADS)

Liu, Liqun; Fan, Haifeng

In order to deal with the uncertainty of evidences mostly existing in pineapple disease identification system, a reasoning model based on evidence credibility factor was established. The uncertainty reasoning method is discussed,including: uncertain representation of knowledge, uncertain representation of rules, uncertain representation of multi-evidences and update of reasoning rules. The reasoning can fully reflect the uncertainty in disease identification and reduce the influence of subjective factors on the accuracy of the system.

The IT Advantage Assessment Model: Applying an Expanded Value Chain Model to Academia

ERIC Educational Resources Information Center

Turner, Walter L.; Stylianou, Antonis C.

2004-01-01

Academia faces an uncertain future as the 21st century unfolds. New demands, discerning students, increased competition from non-traditional competitors are just a few of the forces demanding a response. The use of information technology (IT) in academia has not kept pace with its use in industry. What has been lacking is a model for the strategic…

DOS cones along atomic chains

NASA Astrophysics Data System (ADS)

Kwapiński, Tomasz

2017-03-01

The electron transport properties of a linear atomic chain are studied theoretically within the tight-binding Hamiltonian and the Green’s function method. Variations of the local density of states (DOS) along the chain are investigated. They are crucial in scanning tunnelling experiments and give important insight into the electron transport mechanism and charge distribution inside chains. It is found that depending on the chain parity the local DOS at the Fermi level can form cone-like structures (DOS cones) along the chain. The general condition for the local DOS oscillations is obtained and the linear behaviour of the local density function is confirmed analytically. DOS cones are characterized by a linear decay towards the chain which is in contrast to the propagation properties of charge density waves, end states and Friedel oscillations in one-dimensional systems. We find that DOS cones can appear due to non-resonant electron transport, the spin-orbit scattering or for chains fabricated on a substrate with localized electrons. It is also shown that for imperfect chains (e.g. with a reduced coupling strength between two neighboring sites) a diamond-like structure of the local DOS along the chain appears.

Decentralized stochastic control

NASA Technical Reports Server (NTRS)

Speyer, J. L.

1980-01-01

Decentralized stochastic control is characterized by being decentralized in that the information to one controller is not the same as information to another controller. The system including the information has a stochastic or uncertain component. This complicates the development of decision rules which one determines under the assumption that the system is deterministic. The system is dynamic which means the present decisions affect future system responses and the information in the system. This circumstance presents a complex problem where tools like dynamic programming are no longer applicable. These difficulties are discussed from an intuitive viewpoint. Particular assumptions are introduced which allow a limited theory which produces mechanizable affine decision rules.

Improving healthcare value through clinical community and supply chain collaboration.

PubMed

Ishii, Lisa; Demski, Renee; Ken Lee, K H; Mustafa, Zishan; Frank, Steve; Wolisnky, Jean Paul; Cohen, David; Khanna, Jay; Ammerman, Joshua; Khanuja, Harpal S; Unger, Anthony S; Gould, Lois; Wachter, Patricia Ann; Stearns, Lauren; Werthman, Ronald; Pronovost, Peter

2017-03-01

We hypothesized that integrating supply chain with clinical communities would allow for clinician-led supply cost reduction and improved value in an academic health system. Three clinical communities (spine, joint, blood management) and one clinical community-like physician led team of surgeon stakeholders partnered with the supply chain team on specific supply cost initiatives. The teams reviewed their specific utilization and cost data, and the physicians led consensus-building conversations over a series of team meetings to agree to standard supply utilization. The spine and joint clinical communities each agreed upon a vendor capping model that led to cost savings of $3 million dollars and $1.5 million dollars respectively. The blood management decreased blood product utilization and achieved $1.2 million dollars savings. $5.6 million dollars in savings was achieved by a clinical community-like group of surgeon stakeholders through standardization of sutures and endomechanicals. Physician led clinical teams empowered to lead change achieved substantial supply chain cost savings in an academic health system. The model of combining clinical communities with supply chain offers hope for an effective, practical, and scalable approach to improving value and engaging physicians in other academic health systems. This clinician led model could benefit both private and academic health systems engaging in value optimization efforts. N/A. Copyright © 2016 Elsevier Inc. All rights reserved.

A flower-like Ising model. Thermodynamic properties

NASA Astrophysics Data System (ADS)

Mejdani, R.; Ifti, M.

1995-03-01

We consider a flower-like Ising model, in which there are some additional bonds (in the “flower-core”) compared to a pure Ising chain. To understand the behaviour of this system and particularly the competition between ferromagnetic (usual) bonds along the chain and antiferromagnetic (additional) bonds across the chain, we study analytically and iteratively the main thermodynamic quantities. Very interesting is, in the zero-field and zero-temperature limit, the behaviour of the magnetization and the susceptibility, closely related to the ground state configurations and their degeneracies. This degeneracy explains the existence of non-zero entropy at zero temperature, in our results. Also, this model could be useful for the experimental investigations in studying the saturation curves for the enzyme kinetics or the melting curves for DNA-denaturation in some flower-like configurations.

Intelligent robust control for uncertain nonlinear time-varying systems and its application to robotic systems.

PubMed

Chang, Yeong-Chan

2005-12-01

This paper addresses the problem of designing adaptive fuzzy-based (or neural network-based) robust controls for a large class of uncertain nonlinear time-varying systems. This class of systems can be perturbed by plant uncertainties, unmodeled perturbations, and external disturbances. Nonlinear H(infinity) control technique incorporated with adaptive control technique and VSC technique is employed to construct the intelligent robust stabilization controller such that an H(infinity) control is achieved. The problem of the robust tracking control design for uncertain robotic systems is employed to demonstrate the effectiveness of the developed robust stabilization control scheme. Therefore, an intelligent robust tracking controller for uncertain robotic systems in the presence of high-degree uncertainties can easily be implemented. Its solution requires only to solve a linear algebraic matrix inequality and a satisfactorily transient and asymptotical tracking performance is guaranteed. A simulation example is made to confirm the performance of the developed control algorithms.

Assessing risk based on uncertain avalanche activity patterns

NASA Astrophysics Data System (ADS)

Zeidler, Antonia; Fromm, Reinhard

2015-04-01

Avalanches may affect critical infrastructure and may cause great economic losses. The planning horizon of infrastructures, e.g. hydropower generation facilities, reaches well into the future. Based on the results of previous studies on the effect of changing meteorological parameters (precipitation, temperature) and the effect on avalanche activity we assume that there will be a change of the risk pattern in future. The decision makers need to understand what the future might bring to best formulate their mitigation strategies. Therefore, we explore a commercial risk software to calculate risk for the coming years that might help in decision processes. The software @risk, is known to many larger companies, and therefore we explore its capabilities to include avalanche risk simulations in order to guarantee a comparability of different risks. In a first step, we develop a model for a hydropower generation facility that reflects the problem of changing avalanche activity patterns in future by selecting relevant input parameters and assigning likely probability distributions. The uncertain input variables include the probability of avalanches affecting an object, the vulnerability of an object, the expected costs for repairing the object and the expected cost due to interruption. The crux is to find the distribution that best represents the input variables under changing meteorological conditions. Our focus is on including the uncertain probability of avalanches based on the analysis of past avalanche data and expert knowledge. In order to explore different likely outcomes we base the analysis on three different climate scenarios (likely, worst case, baseline). For some variables, it is possible to fit a distribution to historical data, whereas in cases where the past dataset is insufficient or not available the software allows to select from over 30 different distribution types. The Monte Carlo simulation uses the probability distribution of uncertain variables using all valid combinations of the values of input variables to simulate all possible outcomes. In our case the output is the expected risk (Euro/year) for each object (e.g. water intake) considered and the entire hydropower generation system. The output is again a distribution that is interpreted by the decision makers as the final strategy depends on the needs and requirements of the end-user, which may be driven by personal preferences. In this presentation, we will show a way on how we used the uncertain information on avalanche activity in future to subsequently use it in a commercial risk software and therefore bringing the knowledge of natural hazard experts to decision makers.

Use of fuzzy sets in modeling of GIS objects

NASA Astrophysics Data System (ADS)

Mironova, Yu N.

2018-05-01

The paper discusses modeling and methods of data visualization in geographic information systems. Information processing in Geoinformatics is based on the use of models. Therefore, geoinformation modeling is a key in the chain of GEODATA processing. When solving problems, using geographic information systems often requires submission of the approximate or insufficient reliable information about the map features in the GIS database. Heterogeneous data of different origin and accuracy have some degree of uncertainty. In addition, not all information is accurate: already during the initial measurements, poorly defined terms and attributes (e.g., "soil, well-drained") are used. Therefore, there are necessary methods for working with uncertain requirements, classes, boundaries. The author proposes using spatial information fuzzy sets. In terms of a characteristic function, a fuzzy set is a natural generalization of ordinary sets, when one rejects the binary nature of this feature and assumes that it can take any value in the interval.

Preparing for an Uncertain Forecast

ERIC Educational Resources Information Center

Karolak, Eric

2011-01-01

Navigating the world of government relations and public policy can be a little like predicting the weather. One can't always be sure what's in store or how it will affect him/her down the road. But there are common patterns and a few basic steps that can help one best prepare for a change in the forecast. Though the forecast is uncertain, early…

Trusted Defense Microelectronics: Future Access and Capabilities Are Uncertain

DTIC Science & Technology

2015-10-28

Board Task Force on High Performance Microchip Supply and documentation and discussions with industry and DOD officials in September and October...the defense and microelectronics industry . DOD’s review of this report deemed some of this information as sensitive but unclassified. What GAO...increased specialization and industry consolidation. • Once dominated by domestic sources, the supply chain for microelectronics manufacturing is a global one

Does message framing predict willingness to participate in a hypothetical HIV vaccine trial: an application of Prospect Theory.

PubMed

Evangeli, Michael; Kafaar, Zuhayr; Kagee, Ashraf; Swartz, Leslie; Bullemor-Day, Philippa

2013-01-01

It is vital that enough participants are willing to participate in clinical trials to test HIV vaccines adequately. It is, therefore, necessary to explore what affects peoples' willingness to participate (WTP) in such trials. Studies have only examined individual factors associated with WTP and not the effect of messages about trial participation on potential participants (e.g., whether losses or gains are emphasized, or whether the outcome is certain or uncertain). This study explores whether the effects of message framing on WTP in a hypothetical HIV vaccine trial are consistent with Prospect Theory. This theory suggests that people are fundamentally risk averse and that (1) under conditions of low risk and high certainty, gain-framed messages will be influential (2) under conditions of high risk and low certainty, loss-framed messages will be influential. This cross-sectional study recruited 283 HIV-negative students from a South African university who were given a questionnaire that contained matched certain gain-framed, certain loss-framed, uncertain gain-framed, and uncertain loss-framed statements based on common barriers and facilitators of WTP. Participants were asked to rate how likely each statement was to result in their participation in a hypothetical preventative HIV vaccine trial. Consistent with Prospect Theory predictions, for certain outcomes, gain-framed messages were more likely to result in WTP than loss-framed messages. Inconsistent with predictions, loss-framed message were not more likely to be related to WTP for uncertain outcomes than gain-framed messages. Older students were less likely to express their WTP across the different message frames. Recruitment for HIV vaccine trials should pay attention to how messages about the trial are presented to potential participants.

The serotonergic system and anxiety.

PubMed

Gordon, Joshua A; Hen, Rene

2004-01-01

The wide use of serotonin reuptake inhibitors and serotonin receptor agonists in anxiety disorders has suggested a key role for the modulatory neurotransmitter in anxiety. However, serotonin's specific role is still uncertain. This article reviews the literature concerning how and where serotonergic agents modulate anxiety. Varying and sometimes conflicting data from human and animal studies argue for both anxiolytic and anxiogenic roles for serotonin, depending on the specific disorder, structure, or behavioral task studied. However, recent data from molecular genetic studies in the mouse point toward two important roles for the serotonin 1A receptor. In development, serotonin acts through this receptor to promote development of the circuitry necessary for normal anxiety-like behaviors. In adulthood, serotonin reuptake inhibitors act through the same receptor to stimulate neurogenesis and reduce anxiety-like behaviors. These studies highlight that the complex serotonin system likely plays various roles in the regulation of anxiety both during development and in adulthood.

Accounting for indirect land-use change in the life cycle assessment of biofuel supply chains

PubMed Central

Sanchez, Susan Tarka; Woods, Jeremy; Akhurst, Mark; Brander, Matthew; O'Hare, Michael; Dawson, Terence P.; Edwards, Robert; Liska, Adam J.; Malpas, Rick

2012-01-01

The expansion of land used for crop production causes variable direct and indirect greenhouse gas emissions, and other economic, social and environmental effects. We analyse the use of life cycle analysis (LCA) for estimating the carbon intensity of biofuel production from indirect land-use change (ILUC). Two approaches are critiqued: direct, attributional life cycle analysis and consequential life cycle analysis (CLCA). A proposed hybrid ‘combined model’ of the two approaches for ILUC analysis relies on first defining the system boundary of the resulting full LCA. Choices are then made as to the modelling methodology (economic equilibrium or cause–effect), data inputs, land area analysis, carbon stock accounting and uncertainty analysis to be included. We conclude that CLCA is applicable for estimating the historic emissions from ILUC, although improvements to the hybrid approach proposed, coupled with regular updating, are required, and uncertainly values must be adequately represented; however, the scope and the depth of the expansion of the system boundaries required for CLCA remain controversial. In addition, robust prediction, monitoring and accounting frameworks for the dynamic and highly uncertain nature of future crop yields and the effectiveness of policies to reduce deforestation and encourage afforestation remain elusive. Finally, establishing compatible and comparable accounting frameworks for ILUC between the USA, the European Union, South East Asia, Africa, Brazil and other major biofuel trading blocs is urgently needed if substantial distortions between these markets, which would reduce its application in policy outcomes, are to be avoided. PMID:22467143

Accounting for indirect land-use change in the life cycle assessment of biofuel supply chains.

PubMed

Sanchez, Susan Tarka; Woods, Jeremy; Akhurst, Mark; Brander, Matthew; O'Hare, Michael; Dawson, Terence P; Edwards, Robert; Liska, Adam J; Malpas, Rick

2012-06-07

The expansion of land used for crop production causes variable direct and indirect greenhouse gas emissions, and other economic, social and environmental effects. We analyse the use of life cycle analysis (LCA) for estimating the carbon intensity of biofuel production from indirect land-use change (ILUC). Two approaches are critiqued: direct, attributional life cycle analysis and consequential life cycle analysis (CLCA). A proposed hybrid 'combined model' of the two approaches for ILUC analysis relies on first defining the system boundary of the resulting full LCA. Choices are then made as to the modelling methodology (economic equilibrium or cause-effect), data inputs, land area analysis, carbon stock accounting and uncertainty analysis to be included. We conclude that CLCA is applicable for estimating the historic emissions from ILUC, although improvements to the hybrid approach proposed, coupled with regular updating, are required, and uncertainly values must be adequately represented; however, the scope and the depth of the expansion of the system boundaries required for CLCA remain controversial. In addition, robust prediction, monitoring and accounting frameworks for the dynamic and highly uncertain nature of future crop yields and the effectiveness of policies to reduce deforestation and encourage afforestation remain elusive. Finally, establishing compatible and comparable accounting frameworks for ILUC between the USA, the European Union, South East Asia, Africa, Brazil and other major biofuel trading blocs is urgently needed if substantial distortions between these markets, which would reduce its application in policy outcomes, are to be avoided.

Chain of care development in Sweden: results of a national study

PubMed Central

Åhgren, Bengt

2003-01-01

Abstract Chains of Care are today an important counterbalance to the ever-increasing fragmentation of Swedish health care, and the ongoing development work has high priority. Improved quality of care is the most important reason for developing Chains of Care. Despite support in the form of goals and activity plans, seven out of ten county councils are uncertain whether they have been quite successful in the development work. Strong departmentalisation of responsibilities between different medical professions and departments, types of responsibilities and power still remaining in the vertical organisation structure, together with limited participation from the local authorities, are some of the most commonly mentioned reasons for the lack of success. Even though there is hesitation regarding the development work up to today, all county councils will continue developing Chains of Care. The main reason is, as was the case with Chain of Care development up to today, to improve quality of care. Although one of the main purposes is to make health care more patient-focused, patients in general seem to have limited impact on the development work. Therefore, the challenge is to design Chains of Care, which regards patients as partners instead of objects. PMID:16896423

Systems metabolic engineering design: Fatty acid production as an emerging case study

PubMed Central

Tee, Ting Wei; Chowdhury, Anupam; Maranas, Costas D; Shanks, Jacqueline V

2014-01-01

Increasing demand for petroleum has stimulated industry to develop sustainable production of chemicals and biofuels using microbial cell factories. Fatty acids of chain lengths from C6 to C16 are propitious intermediates for the catalytic synthesis of industrial chemicals and diesel-like biofuels. The abundance of genetic information available for Escherichia coli and specifically, fatty acid metabolism in E. coli, supports this bacterium as a promising host for engineering a biocatalyst for the microbial production of fatty acids. Recent successes rooted in different features of systems metabolic engineering in the strain design of high-yielding medium chain fatty acid producing E. coli strains provide an emerging case study of design methods for effective strain design. Classical metabolic engineering and synthetic biology approaches enabled different and distinct design paths towards a high-yielding strain. Here we highlight a rational strain design process in systems biology, an integrated computational and experimental approach for carboxylic acid production, as an alternative method. Additional challenges inherent in achieving an optimal strain for commercialization of medium chain-length fatty acids will likely require a collection of strategies from systems metabolic engineering. Not only will the continued advancement in systems metabolic engineering result in these highly productive strains more quickly, this knowledge will extend more rapidly the carboxylic acid platform to the microbial production of carboxylic acids with alternate chain-lengths and functionalities. PMID:24481660

Systems metabolic engineering design: fatty acid production as an emerging case study.

PubMed

Tee, Ting Wei; Chowdhury, Anupam; Maranas, Costas D; Shanks, Jacqueline V

2014-05-01

Increasing demand for petroleum has stimulated industry to develop sustainable production of chemicals and biofuels using microbial cell factories. Fatty acids of chain lengths from C6 to C16 are propitious intermediates for the catalytic synthesis of industrial chemicals and diesel-like biofuels. The abundance of genetic information available for Escherichia coli and specifically, fatty acid metabolism in E. coli, supports this bacterium as a promising host for engineering a biocatalyst for the microbial production of fatty acids. Recent successes rooted in different features of systems metabolic engineering in the strain design of high-yielding medium chain fatty acid producing E. coli strains provide an emerging case study of design methods for effective strain design. Classical metabolic engineering and synthetic biology approaches enabled different and distinct design paths towards a high-yielding strain. Here we highlight a rational strain design process in systems biology, an integrated computational and experimental approach for carboxylic acid production, as an alternative method. Additional challenges inherent in achieving an optimal strain for commercialization of medium chain-length fatty acids will likely require a collection of strategies from systems metabolic engineering. Not only will the continued advancement in systems metabolic engineering result in these highly productive strains more quickly, this knowledge will extend more rapidly the carboxylic acid platform to the microbial production of carboxylic acids with alternate chain-lengths and functionalities. © 2014 Wiley Periodicals, Inc.

Time-delayed chameleon: Analysis, synchronization and FPGA implementation

NASA Astrophysics Data System (ADS)

Rajagopal, Karthikeyan; Jafari, Sajad; Laarem, Guessas

2017-12-01

In this paper we report a time-delayed chameleon-like chaotic system which can belong to different families of chaotic attractors depending on the choices of parameters. Such a characteristic of self-excited and hidden chaotic flows in a simple 3D system with time delay has not been reported earlier. Dynamic analysis of the proposed time-delayed systems are analysed in time-delay space and parameter space. A novel adaptive modified functional projective lag synchronization algorithm is derived for synchronizing identical time-delayed chameleon systems with uncertain parameters. The proposed time-delayed systems and the synchronization algorithm with controllers and parameter estimates are then implemented in FPGA using hardware-software co-simulation and the results are presented.

Enzymes involved in branched-chain amino acid metabolism in humans.

PubMed

Adeva-Andany, María M; López-Maside, Laura; Donapetry-García, Cristóbal; Fernández-Fernández, Carlos; Sixto-Leal, Cristina

2017-06-01

Branched-chain amino acids (leucine, isoleucine and valine) are structurally related to branched-chain fatty acids. Leucine is 2-amino-4-methyl-pentanoic acid, isoleucine is 2-amino-3-methyl-pentanoic acid, and valine is 2-amino-3-methyl-butanoic acid. Similar to fatty acid oxidation, leucine and isoleucine produce acetyl-coA. Additionally, leucine generates acetoacetate and isoleucine yields propionyl-coA. Valine oxidation produces propionyl-coA, which is converted into methylmalonyl-coA and succinyl-coA. Branched-chain aminotransferase catalyzes the first reaction in the catabolic pathway of branched-chain amino acids, a reversible transamination that converts branched-chain amino acids into branched-chain ketoacids. Simultaneously, glutamate is converted in 2-ketoglutarate. The branched-chain ketoacid dehydrogenase complex catalyzes the irreversible oxidative decarboxylation of branched-chain ketoacids to produce branched-chain acyl-coA intermediates, which then follow separate catabolic pathways. Human tissue distribution and function of most of the enzymes involved in branched-chain amino acid catabolism is unknown. Congenital deficiencies of the enzymes involved in branched-chain amino acid metabolism are generally rare disorders. Some of them are associated with reduced pyruvate dehydrogenase complex activity and respiratory chain dysfunction that may contribute to their clinical phenotype. The biochemical phenotype is characterized by accumulation of the substrate to the deficient enzyme and its carnitine and/or glycine derivatives. It was established at the beginning of the twentieth century that the plasma level of the branched-chain amino acids is increased in conditions associated with insulin resistance such as obesity and diabetes mellitus. However, the potential clinical relevance of this elevation is uncertain.

Evaluation of Ares-I Control System Robustness to Uncertain Aerodynamics and Flex Dynamics

NASA Technical Reports Server (NTRS)

Jang, Jiann-Woei; VanTassel, Chris; Bedrossian, Nazareth; Hall, Charles; Spanos, Pol

2008-01-01

This paper discusses the application of robust control theory to evaluate robustness of the Ares-I control systems. Three techniques for estimating upper and lower bounds of uncertain parameters which yield stable closed-loop response are used here: (1) Monte Carlo analysis, (2) mu analysis, and (3) characteristic frequency response analysis. All three methods are used to evaluate stability envelopes of the Ares-I control systems with uncertain aerodynamics and flex dynamics. The results show that characteristic frequency response analysis is the most effective of these methods for assessing robustness.

Atwood's Heavy Chain

ERIC Educational Resources Information Center

Beeken, Paul

2011-01-01

While perusing various websites in search of a more challenging lab for my students, I came across a number of ideas where replacing the string in an Atwood's machine with a simple ball chain like the kind found in lamp pulls created an interesting system to investigate. The replacement of the string produced a nice nonuniform acceleration, but…

Markov Chain Monte Carlo estimation of species distributions: a case study of the swift fox in western Kansas

USGS Publications Warehouse

Sargeant, Glen A.; Sovada, Marsha A.; Slivinski, Christiane C.; Johnson, Douglas H.

2005-01-01

Accurate maps of species distributions are essential tools for wildlife research and conservation. Unfortunately, biologists often are forced to rely on maps derived from observed occurrences recorded opportunistically during observation periods of variable length. Spurious inferences are likely to result because such maps are profoundly affected by the duration and intensity of observation and by methods used to delineate distributions, especially when detection is uncertain. We conducted a systematic survey of swift fox (Vulpes velox) distribution in western Kansas, USA, and used Markov chain Monte Carlo (MCMC) image restoration to rectify these problems. During 1997–1999, we searched 355 townships (ca. 93 km) 1–3 times each for an average cost of $7,315 per year and achieved a detection rate (probability of detecting swift foxes, if present, during a single search) of = 0.69 (95% Bayesian confidence interval [BCI] = [0.60, 0.77]). Our analysis produced an estimate of the underlying distribution, rather than a map of observed occurrences, that reflected the uncertainty associated with estimates of model parameters. To evaluate our results, we analyzed simulated data with similar properties. Results of our simulations suggest negligible bias and good precision when probabilities of detection on ≥1 survey occasions (cumulative probabilities of detection) exceed 0.65. Although the use of MCMC image restoration has been limited by theoretical and computational complexities, alternatives do not possess the same advantages. Image models accommodate uncertain detection, do not require spatially independent data or a census of map units, and can be used to estimate species distributions directly from observations without relying on habitat covariates or parameters that must be estimated subjectively. These features facilitate economical surveys of large regions, the detection of temporal trends in distribution, and assessments of landscape-level relations between species and habitats. Requirements for the use of MCMC image restoration include study areas that can be partitioned into regular grids of mapping units, spatially contagious species distributions, reliable methods for identifying target species, and cumulative probabilities of detection ≥0.65.

Markov chain Monte Carlo estimation of species distributions: A case study of the swift fox in western Kansas

USGS Publications Warehouse

Sargeant, G.A.; Sovada, M.A.; Slivinski, C.C.; Johnson, D.H.

2005-01-01

Accurate maps of species distributions are essential tools for wildlife research and conservation. Unfortunately, biologists often are forced to rely on maps derived from observed occurrences recorded opportunistically during observation periods of variable length. Spurious inferences are likely to result because such maps are profoundly affected by the duration and intensity of observation and by methods used to delineate distributions, especially when detection is uncertain. We conducted a systematic survey of swift fox (Vulpes velox) distribution in western Kansas, USA, and used Markov chain Monte Carlo (MCMC) image restoration to rectify these problems. During 1997-1999, we searched 355 townships (ca. 93 km2) 1-3 times each for an average cost of $7,315 per year and achieved a detection rate (probability of detecting swift foxes, if present, during a single search) of ?? = 0.69 (95% Bayesian confidence interval [BCI] = [0.60, 0.77]). Our analysis produced an estimate of the underlying distribution, rather than a map of observed occurrences, that reflected the uncertainty associated with estimates of model parameters. To evaluate our results, we analyzed simulated data with similar properties. Results of our simulations suggest negligible bias and good precision when probabilities of detection on ???1 survey occasions (cumulative probabilities of detection) exceed 0.65. Although the use of MCMC image restoration has been limited by theoretical and computational complexities, alternatives do not possess the same advantages. Image models accommodate uncertain detection, do not require spatially independent data or a census of map units, and can be used to estimate species distributions directly from observations without relying on habitat covariates or parameters that must be estimated subjectively. These features facilitate economical surveys of large regions, the detection of temporal trends in distribution, and assessments of landscape-level relations between species and habitats. Requirements for the use of MCMC image restoration include study areas that can be partitioned into regular grids of mapping units, spatially contagious species distributions, reliable methods for identifying target species, and cumulative probabilities of detection ???0.65.

Dynamics and motion control of a chain of particles on a rough surface

NASA Astrophysics Data System (ADS)

Behn, C.; Schale, F.; Zeidis, I.; Zimmermann, K.; Bolotnik, N.

2017-05-01

In this paper the mechanics and control of the motion of a straight chain of three particles interconnected with kinematical constraints are investigated. The ground contact is described by dry (discontinuous) or viscous (continuous) friction. Here, we understand this model as a methodological basis for the design of worm-like locomotion systems, i.e., non-pedal mobile robots. This kind of robots will prove an efficient form of locomotion in application to inspection of pipes or for rescue missions. In this paper, a number of issues related to the dynamics and control of artificial limbless locomotion systems are discussed. Simplest models of a limbless locomotor are two-body or three-body systems that move along a horizontal straight line. In the first part of the paper, the controls are assumed in the form of periodic functions with zero average, shifted on a phase one concerning each other. Thus, there is a traveling wave along the chain of particles. In the second part, actuator models are discussed. It is supposed that there are unknown actuator data or the worm system parameter are not known or exactly as well. The focus is on adaptive control algorithms for the worm-like locomotion systems in order to track given reference trajectories, like kinematic gaits. Finally, a prototype together with its signal processing and control software is presented. Theoretically (analytically and numerically) calculated results of the dynamical behavior of the mobile system are compared to experimental data.

Amide or Amine: Determining the Origin of the 3300 cm−1 NH Mode in Protein SFG Spectra Using 15N Isotope Labels

PubMed Central

Weidner, Tobias; Breen, Nicholas F.; Drobny, Gary P.; Castner, David G.

2009-01-01

Sum frequency generation (SFG) vibrational spectroscopy has been employed in biomaterials research and protein adsorption studies with growing success in recent years. A number of studies focusing on understanding SFG spectra of proteins and peptides at different interfaces have laid the foundation for future, more complex studies. In many cases a strong NH mode near 3300 cm−1 is observed in the SFG spectra, but the relationship of this mode to the peptide structure is uncertain since it has been assigned to either a backbone amide mode or a side chain related amine resonance. A thorough understanding of the SFG spectra of these first model systems is an important first step for future experiments. To clarify the origin of the NH SFG mode we studied 15N isotopically labeled 14-amino acid amphiphilic model peptides composed of lysine (K) and leucine (L) in an α-helical secondary structure (LKα14) that were adsorbed onto charged surfaces in situ at the solid-liquid interface. 15N substitution at the terminal amine group of the lysine side chains resulted in a red-shift of the NH mode of 9 cm−1 on SiO2 and 13 cm−1 on CaF2. This clearly shows the 3300 cm−1 NH feature is associated with side chain NH stretches and not with backbone amide modes. PMID:19873996

Amide or amine: determining the origin of the 3300 cm(-1) NH mode in protein SFG spectra using 15N isotope labels.

PubMed

Weidner, Tobias; Breen, Nicholas F; Drobny, Gary P; Castner, David G

2009-11-26

Sum frequency generation (SFG) vibrational spectroscopy has been employed in biomaterials research and protein adsorption studies with growing success in recent years. A number of studies focusing on understanding SFG spectra of proteins and peptides at different interfaces have laid the foundation for future, more complex studies. In many cases, a strong NH mode near 3300 cm(-1) is observed in the SFG spectra, but the relationship of this mode to the peptide structure is uncertain, since it has been assigned to either a backbone amide mode or a side chain related amine resonance. A thorough understanding of the SFG spectra of these first model systems is an important first step for future experiments. To clarify the origin of the NH SFG mode, we studied (15)N isotopically labeled 14-amino acid amphiphilic model peptides composed of lysine (K) and leucine (L) in an alpha-helical secondary structure (LKalpha14) that were adsorbed onto charged surfaces in situ at the solid-liquid interface. (15)N substitution at the terminal amine group of the lysine side chains resulted in a red-shift of the NH mode of 9 cm(-1) on SiO(2) and 13 cm(-1) on CaF(2). This clearly shows the 3300 cm(-1) NH feature is associated with side chain NH stretches and not with backbone amide modes.

Understanding and reducing the risk of supply chain disruptions.

PubMed

Clark, Graham

2012-01-01

Natural disasters can wreck havoc on business operations. When civil unrest swept the UK in August 2011, the effect on business was stark, losing the retail sector £300m in unexpected costs and lost revenues. On the other side of the world, the natural disaster that hit Japan in early 2011 is estimated to have run up costs in the region of £189bn in repairs. Beyond this, the earthquake and its aftermath shattered supply chains, with technology companies expecting delays of up to six months before business could resume fully. It is impossible to predict incidents like these, but businesses can help mitigate disruption in the supply chain by undertaking business continuity management (BCM). A flexible supply chain is essential when it comes to BCM - whether it means being able to cope with altering transport routes at short notice, or finding or replacing a supplier at the last minute. Understanding the supply chain is critical when responding to major impacts that affect supply chains in multiple points - like IT system failures and country-wide fuel strikes. Businesses should carry out detailed business impact assessments and risk assessments right across the end-to-end supply chain and not just at key single points of failure. It is an intensive process that needs dedicated resources and ownership at the highest level. Recognising this, DHL has designed a 10-step process, which it has implemented across its global supply chain business. This paper provides an overview of what a supply chain really looks like, what can cause disruptions and how far up/down the supply chain companies need to go with their BCM planning.

Supply chain dynamics in healthcare services.

PubMed

Samuel, Cherian; Gonapa, Kasiviswanadh; Chaudhary, P K; Mishra, Ananya

2010-01-01

The purpose of this paper is to analyse health service supply chain systems. A great deal of literature is available on supply chain management in finished goods inventory situations; however, little research exists on managing service capacity when finished goods inventories are absent. System dynamics models for a typical service-oriented supply chain such as healthcare processes are developed, wherein three service stages are presented sequentially. Just like supply chains with finished goods inventory, healthcare service supply chains also show dynamic behaviour. Comparing options, service reduction, and capacity adjustment delays showed that reducing capacity adjustment and service delays gives better results. The study is confined to health service-oriented supply chains. Further work includes extending the study to service-oriented supply chains with parallel processing, i.e. having more than one stage to perform a similar operation and also to study the behaviour in service-oriented supply chains that have re-entrant orders and applications. Specific case studies can also be developed to reveal factors relevant to particular service-oriented supply chains. The paper explains the bullwhip effect in healthcare service-oriented supply chains. Reducing stages and capacity adjustment are strategic options for service-oriented supply chains. The paper throws light on policy options for managing healthcare service-oriented supply chain dynamics.

Simulation-optimization model for production planning in the blood supply chain.

PubMed

Osorio, Andres F; Brailsford, Sally C; Smith, Honora K; Forero-Matiz, Sonia P; Camacho-Rodríguez, Bernardo A

2017-12-01

Production planning in the blood supply chain is a challenging task. Many complex factors such as uncertain supply and demand, blood group proportions, shelf life constraints and different collection and production methods have to be taken into account, and thus advanced methodologies are required for decision making. This paper presents an integrated simulation-optimization model to support both strategic and operational decisions in production planning. Discrete-event simulation is used to represent the flows through the supply chain, incorporating collection, production, storing and distribution. On the other hand, an integer linear optimization model running over a rolling planning horizon is used to support daily decisions, such as the required number of donors, collection methods and production planning. This approach is evaluated using real data from a blood center in Colombia. The results show that, using the proposed model, key indicators such as shortages, outdated units, donors required and cost are improved.

Fuzzy Stochastic Petri Nets for Modeling Biological Systems with Uncertain Kinetic Parameters

PubMed Central

Liu, Fei; Heiner, Monika; Yang, Ming

2016-01-01

Stochastic Petri nets (SPNs) have been widely used to model randomness which is an inherent feature of biological systems. However, for many biological systems, some kinetic parameters may be uncertain due to incomplete, vague or missing kinetic data (often called fuzzy uncertainty), or naturally vary, e.g., between different individuals, experimental conditions, etc. (often called variability), which has prevented a wider application of SPNs that require accurate parameters. Considering the strength of fuzzy sets to deal with uncertain information, we apply a specific type of stochastic Petri nets, fuzzy stochastic Petri nets (FSPNs), to model and analyze biological systems with uncertain kinetic parameters. FSPNs combine SPNs and fuzzy sets, thereby taking into account both randomness and fuzziness of biological systems. For a biological system, SPNs model the randomness, while fuzzy sets model kinetic parameters with fuzzy uncertainty or variability by associating each parameter with a fuzzy number instead of a crisp real value. We introduce a simulation-based analysis method for FSPNs to explore the uncertainties of outputs resulting from the uncertainties associated with input parameters, which works equally well for bounded and unbounded models. We illustrate our approach using a yeast polarization model having an infinite state space, which shows the appropriateness of FSPNs in combination with simulation-based analysis for modeling and analyzing biological systems with uncertain information. PMID:26910830

Adaptive Fault-Tolerant Control of Uncertain Nonlinear Large-Scale Systems With Unknown Dead Zone.

PubMed

Chen, Mou; Tao, Gang

2016-08-01

In this paper, an adaptive neural fault-tolerant control scheme is proposed and analyzed for a class of uncertain nonlinear large-scale systems with unknown dead zone and external disturbances. To tackle the unknown nonlinear interaction functions in the large-scale system, the radial basis function neural network (RBFNN) is employed to approximate them. To further handle the unknown approximation errors and the effects of the unknown dead zone and external disturbances, integrated as the compounded disturbances, the corresponding disturbance observers are developed for their estimations. Based on the outputs of the RBFNN and the disturbance observer, the adaptive neural fault-tolerant control scheme is designed for uncertain nonlinear large-scale systems by using a decentralized backstepping technique. The closed-loop stability of the adaptive control system is rigorously proved via Lyapunov analysis and the satisfactory tracking performance is achieved under the integrated effects of unknown dead zone, actuator fault, and unknown external disturbances. Simulation results of a mass-spring-damper system are given to illustrate the effectiveness of the proposed adaptive neural fault-tolerant control scheme for uncertain nonlinear large-scale systems.

Learning How the Electron Transport Chain Works: Independent and Interactive Effects of Instructional Strategies and Learners' Characteristics

ERIC Educational Resources Information Center

Darabi, Aubteen; Arrastia-Lloyd, Meagan C.; Nelson, David W.; Liang, Xinya; Farrell, Jennifer

2015-01-01

In order to develop an expert-like mental model of complex systems, causal reasoning is essential. This study examines the differences between forward and backward instructional strategies in terms of efficiency, students' learning and progression of their mental models of the electronic transport chain in an undergraduate metabolism course…

Robust control synthesis for uncertain dynamical systems

NASA Technical Reports Server (NTRS)

Byun, Kuk-Whan; Wie, Bong; Sunkel, John

1989-01-01

This paper presents robust control synthesis techniques for uncertain dynamical systems subject to structured parameter perturbation. Both QFT (quantitative feedback theory) and H-infinity control synthesis techniques are investigated. Although most H-infinity-related control techniques are not concerned with the structured parameter perturbation, a new way of incorporating the parameter uncertainty in the robust H-infinity control design is presented. A generic model of uncertain dynamical systems is used to illustrate the design methodologies investigated in this paper. It is shown that, for a certain noncolocated structural control problem, use of both techniques results in nonminimum phase compensation.

Detachment of Chain-Forming Neuroblasts by Fyn-Mediated Control of cell-cell Adhesion in the Postnatal Brain.

PubMed

Fujikake, Kazuma; Sawada, Masato; Hikita, Takao; Seto, Yayoi; Kaneko, Naoko; Herranz-Pérez, Vicente; Dohi, Natsuki; Homma, Natsumi; Osaga, Satoshi; Yanagawa, Yuchio; Akaike, Toshihiro; García-Verdugo, Jose Manuel; Hattori, Mitsuharu; Sobue, Kazuya; Sawamoto, Kazunobu

2018-05-09

In the rodent olfactory system, neuroblasts produced in the ventricular-subventricular zone of the postnatal brain migrate tangentially in chain-like cell aggregates toward the olfactory bulb (OB) through the rostral migratory stream (RMS). After reaching the OB, the chains are dissociated and the neuroblasts migrate individually and radially toward their final destination. The cellular and molecular mechanisms controlling cell-cell adhesion during this detachment remain unclear. Here we report that Fyn, a nonreceptor tyrosine kinase, regulates the detachment of neuroblasts from chains in the male and female mouse OB. By performing chemical screening and in vivo loss-of-function and gain-of-function experiments, we found that Fyn promotes somal disengagement from the chains and is involved in neuronal migration from the RMS into the granule cell layer of the OB. Fyn knockdown or Dab1 (disabled-1) deficiency caused p120-catenin to accumulate and adherens junction-like structures to be sustained at the contact sites between neuroblasts. Moreover, a Fyn and N-cadherin double-knockdown experiment indicated that Fyn regulates the N-cadherin-mediated cell adhesion between neuroblasts. These results suggest that the Fyn-mediated control of cell-cell adhesion is critical for the detachment of chain-forming neuroblasts in the postnatal OB. SIGNIFICANCE STATEMENT In the postnatal brain, newly born neurons (neuroblasts) migrate in chain-like cell aggregates toward their destination, where they are dissociated into individual cells and mature. The cellular and molecular mechanisms controlling the detachment of neuroblasts from chains are not understood. Here we show that Fyn, a nonreceptor tyrosine kinase, promotes the somal detachment of neuroblasts from chains, and that this regulation is critical for the efficient migration of neuroblasts to their destination. We further show that Fyn and Dab1 (disabled-1) decrease the cell-cell adhesion between chain-forming neuroblasts, which involves adherens junction-like structures. Our results suggest that Fyn-mediated regulation of the cell-cell adhesion of neuroblasts is critical for their detachment from chains in the postnatal brain. Copyright © 2018 the authors 0270-6474/18/384599-12$15.00/0.

Open Heisenberg chain under boundary fields: A magnonic logic gate

NASA Astrophysics Data System (ADS)

Landi, Gabriel T.; Karevski, Dragi

2015-05-01

We study the spin transport in the quantum Heisenberg spin chain subject to boundary magnetic fields and driven out of equilibrium by Lindblad dissipators. An exact solution is given in terms of matrix product states, which allows us to calculate exactly the spin current for any chain size. It is found that the system undergoes a discontinuous spin-valve-like quantum phase transition from ballistic to subdiffusive spin current, depending on the value of the boundary fields. Thus, the chain behaves as an extremely sensitive magnonic logic gate operating with the boundary fields as the base element.

Challenges in scaling up biofuels infrastructure.

PubMed

Richard, Tom L

2010-08-13

Rapid growth in demand for lignocellulosic bioenergy will require major changes in supply chain infrastructure. Even with densification and preprocessing, transport volumes by mid-century are likely to exceed the combined capacity of current agricultural and energy supply chains, including grain, petroleum, and coal. Efficient supply chains can be achieved through decentralized conversion processes that facilitate local sourcing, satellite preprocessing and densification for long-distance transport, and business models that reward biomass growers both nearby and afar. Integrated systems that are cost-effective and energy-efficient will require new ways of thinking about agriculture, energy infrastructure, and rural economic development. Implementing these integrated systems will require innovation and investment in novel technologies, efficient value chains, and socioeconomic and policy frameworks; all are needed to support an expanded biofuels infrastructure that can meet the challenges of scale.

Strategic Positioning of United States Air Force Civil Engineer Contingency Equipment within the Supply Chain

DTIC Science & Technology

2014-03-27

discussed. Background In a dynamic world full of uncertain threats, the United States military is constantly required to evolve and enhance its...capabilities to effectively defend the nation. One of the military capabilities requiring continuous improvement to ensure pursuit of American...force the right personnel, equipment, and supplies in the right place, at the right time, and in the right quantity, across the full range of military

Molecular conformation of linear alkane molecules: From gas phase to bulk water through the interface

NASA Astrophysics Data System (ADS)

Murina, Ezequiel L.; Fernández-Prini, Roberto; Pastorino, Claudio

2017-08-01

We studied the behavior of long chain alkanes (LCAs) as they were transferred from gas to bulk water, through the liquid-vapor interface. These systems were studied using umbrella sampling molecular dynamics simulation and we have calculated properties like free energy profiles, molecular orientation, and radius of gyration of the LCA molecules. The results show changes in conformation of the solutes along the path. LCAs adopt pronounced molecular orientations and the larger ones extend appreciably when partially immersed in the interface. In bulk water, their conformations up to dodecane are mainly extended. However, larger alkanes like eicosane present a more stable collapsed conformation as they approach bulk water. We have characterized the more probable configurations in all interface and bulk regions. The results obtained are of interest for the study of biomatter processes requiring the transfer of hydrophobic matter, especially chain-like molecules like LCAs, from gas to bulk aqueous systems through the interface.

Robust design of feedback feed-forward iterative learning control based on 2D system theory for linear uncertain systems

NASA Astrophysics Data System (ADS)

Li, Zhifu; Hu, Yueming; Li, Di

2016-08-01

For a class of linear discrete-time uncertain systems, a feedback feed-forward iterative learning control (ILC) scheme is proposed, which is comprised of an iterative learning controller and two current iteration feedback controllers. The iterative learning controller is used to improve the performance along the iteration direction and the feedback controllers are used to improve the performance along the time direction. First of all, the uncertain feedback feed-forward ILC system is presented by an uncertain two-dimensional Roesser model system. Then, two robust control schemes are proposed. One can ensure that the feedback feed-forward ILC system is bounded-input bounded-output stable along time direction, and the other can ensure that the feedback feed-forward ILC system is asymptotically stable along time direction. Both schemes can guarantee the system is robust monotonically convergent along the iteration direction. Third, the robust convergent sufficient conditions are given, which contains a linear matrix inequality (LMI). Moreover, the LMI can be used to determine the gain matrix of the feedback feed-forward iterative learning controller. Finally, the simulation results are presented to demonstrate the effectiveness of the proposed schemes.

Stability of uncertain impulsive complex-variable chaotic systems with time-varying delays.

PubMed

Zheng, Song

2015-09-01

In this paper, the robust exponential stabilization of uncertain impulsive complex-variable chaotic delayed systems is considered with parameters perturbation and delayed impulses. It is assumed that the considered complex-variable chaotic systems have bounded parametric uncertainties together with the state variables on the impulses related to the time-varying delays. Based on the theories of adaptive control and impulsive control, some less conservative and easily verified stability criteria are established for a class of complex-variable chaotic delayed systems with delayed impulses. Some numerical simulations are given to validate the effectiveness of the proposed criteria of impulsive stabilization for uncertain complex-variable chaotic delayed systems. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Adaptive identifier for uncertain complex nonlinear systems based on continuous neural networks.

PubMed

Alfaro-Ponce, Mariel; Cruz, Amadeo Argüelles; Chairez, Isaac

2014-03-01

This paper presents the design of a complex-valued differential neural network identifier for uncertain nonlinear systems defined in the complex domain. This design includes the construction of an adaptive algorithm to adjust the parameters included in the identifier. The algorithm is obtained based on a special class of controlled Lyapunov functions. The quality of the identification process is characterized using the practical stability framework. Indeed, the region where the identification error converges is derived by the same Lyapunov method. This zone is defined by the power of uncertainties and perturbations affecting the complex-valued uncertain dynamics. Moreover, this convergence zone is reduced to its lowest possible value using ideas related to the so-called ellipsoid methodology. Two simple but informative numerical examples are developed to show how the identifier proposed in this paper can be used to approximate uncertain nonlinear systems valued in the complex domain.

Robust cooperation of connected vehicle systems with eigenvalue-bounded interaction topologies in the presence of uncertain dynamics

NASA Astrophysics Data System (ADS)

Li, Keqiang; Gao, Feng; Li, Shengbo Eben; Zheng, Yang; Gao, Hongbo

2017-12-01

This study presents a distributed H-infinity control method for uncertain platoons with dimensionally and structurally unknown interaction topologies provided that the associated topological eigenvalues are bounded by a predesigned range.With an inverse model to compensate for nonlinear powertrain dynamics, vehicles in a platoon are modeled by third-order uncertain systems with bounded disturbances. On the basis of the eigenvalue decomposition of topological matrices, we convert the platoon system to a norm-bounded uncertain part and a diagonally structured certain part by applying linear transformation. We then use a common Lyapunov method to design a distributed H-infinity controller. Numerically, two linear matrix inequalities corresponding to the minimum and maximum eigenvalues should be solved. The resulting controller can tolerate interaction topologies with eigenvalues located in a certain range. The proposed method can also ensure robustness performance and disturbance attenuation ability for the closed-loop platoon system. Hardware-in-the-loop tests are performed to validate the effectiveness of our method.

Homogenization-based interval analysis for structural-acoustic problem involving periodical composites and multi-scale uncertain-but-bounded parameters.

PubMed

Chen, Ning; Yu, Dejie; Xia, Baizhan; Liu, Jian; Ma, Zhengdong

2017-04-01

This paper presents a homogenization-based interval analysis method for the prediction of coupled structural-acoustic systems involving periodical composites and multi-scale uncertain-but-bounded parameters. In the structural-acoustic system, the macro plate structure is assumed to be composed of a periodically uniform microstructure. The equivalent macro material properties of the microstructure are computed using the homogenization method. By integrating the first-order Taylor expansion interval analysis method with the homogenization-based finite element method, a homogenization-based interval finite element method (HIFEM) is developed to solve a periodical composite structural-acoustic system with multi-scale uncertain-but-bounded parameters. The corresponding formulations of the HIFEM are deduced. A subinterval technique is also introduced into the HIFEM for higher accuracy. Numerical examples of a hexahedral box and an automobile passenger compartment are given to demonstrate the efficiency of the presented method for a periodical composite structural-acoustic system with multi-scale uncertain-but-bounded parameters.

Investigating Alkylsilane Monolayer Tribology at a Single-Asperity Contact with Molecular Dynamics Simulation.

PubMed

Summers, Andrew Z; Iacovella, Christopher R; Cummings, Peter T; McCabe, Clare

2017-10-24

Chemisorbed monolayer films are known to possess favorable characteristics for nanoscale lubrication of micro- and nanoelectromechanical systems (MEMS/NEMS). Prior studies have shown that the friction observed for monolayer-coated surfaces features a strong dependence on the geometry of contact. Specifically, tip-like geometries have been shown to penetrate into monolayer films, inducing defects in the monolayer chains and leading to plowing mechanisms during shear, which result in higher coefficients of friction (COF) than those observed for planar geometries. In this work, we use molecular dynamics simulations to examine the tribology of model silica single-asperity contacts under shear with monolayer-coated substrates featuring various film densities. It is observed that lower monolayer densities lead to reduced COFs, in contrast to results for planar systems where COF is found to be nearly independent of monolayer density. This is attributed to a liquid-like response to shear, whereby fewer defects are imparted in monolayer chains from the asperity, and chains are easily displaced by the tip as a result of the higher free volume. This transition in the mechanism of molecular plowing suggests that liquid-like films should provide favorable lubrication at single-asperity contacts.

Electrostatic effects on hyaluronic acid configuration

NASA Astrophysics Data System (ADS)

Berezney, John; Saleh, Omar

2015-03-01

In systems of polyelectrolytes, such as solutions of charged biopolymers, the electrostatic repulsion between charged monomers plays a dominant role in determining the molecular conformation. Altering the ionic strength of the solvent thus affects the structure of such a polymer. Capturing this electrostatically-driven structural dependence is important for understanding many biological systems. Here, we use single molecule manipulation experiments to collect force-extension behavior on hyaluronic acid (HA), a polyanion which is a major component of the extracellular matrix in all vertebrates. By measuring HA elasticity in a variety of salt conditions, we are able to directly assess the contribution of electrostatics to the chain's self-avoidance and local stiffness. Similar to recent results from our group on single-stranded nucleic acids, our data indicate that HA behaves as a swollen chain of electrostatic blobs, with blob size proportional to the solution Debye length. Our data indicate that the chain structure within the blob is not worm-like, likely due to long-range electrostatic interactions. We discuss potential models of this effect.

Secure estimation, control and optimization of uncertain cyber-physical systems with applications to power networks

NASA Astrophysics Data System (ADS)

Taha, Ahmad Fayez

Transportation networks, wearable devices, energy systems, and the book you are reading now are all ubiquitous cyber-physical systems (CPS). These inherently uncertain systems combine physical phenomena with communication, data processing, control and optimization. Many CPSs are controlled and monitored by real-time control systems that use communication networks to transmit and receive data from systems modeled by physical processes. Existing studies have addressed a breadth of challenges related to the design of CPSs. However, there is a lack of studies on uncertain CPSs subject to dynamic unknown inputs and cyber-attacks---an artifact of the insertion of communication networks and the growing complexity of CPSs. The objective of this dissertation is to create secure, computational foundations for uncertain CPSs by establishing a framework to control, estimate and optimize the operation of these systems. With major emphasis on power networks, the dissertation deals with the design of secure computational methods for uncertain CPSs, focusing on three crucial issues---(1) cyber-security and risk-mitigation, (2) network-induced time-delays and perturbations and (3) the encompassed extreme time-scales. The dissertation consists of four parts. In the first part, we investigate dynamic state estimation (DSE) methods and rigorously examine the strengths and weaknesses of the proposed routines under dynamic attack-vectors and unknown inputs. In the second part, and utilizing high-frequency measurements in smart grids and the developed DSE methods in the first part, we present a risk mitigation strategy that minimizes the encountered threat levels, while ensuring the continual observability of the system through available, safe measurements. The developed methods in the first two parts rely on the assumption that the uncertain CPS is not experiencing time-delays, an assumption that might fail under certain conditions. To overcome this challenge, networked unknown input observers---observers/estimators for uncertain CPSs---are designed such that the effect of time-delays and cyber-induced perturbations are minimized, enabling secure DSE and risk mitigation in the first two parts. The final part deals with the extreme time-scales encompassed in CPSs, generally, and smart grids, specifically. Operational decisions for long time-scales can adversely affect the security of CPSs for faster time-scales. We present a model that jointly describes steady-state operation and transient stability by combining convex optimal power flow with semidefinite programming formulations of an optimal control problem. This approach can be jointly utilized with the aforementioned parts of the dissertation work, considering time-delays and DSE. The research contributions of this dissertation furnish CPS stakeholders with insights on the design and operation of uncertain CPSs, whilst guaranteeing the system's real-time safety. Finally, although many of the results of this dissertation are tailored to power systems, the results are general enough to be applied for a variety of uncertain CPSs.

Research on green supply chain coordination strategy for uncertain market demand.

PubMed

Cao, Jian; Chen, Yangyang; Lu, Bo; Tong, Chenlu; Zhou, Gengui

2015-03-01

Based on the status that the green market began to develop (e.g. pharmaceutical industry) in Mainland China, the paper mainly discusses how members of the green supply chain (GSC) cooperate effectively in the process of the supply chain operations. For the uncertainties existing in the market demand of the green products, the GSC coordination strategy is put forward based on the Stackelberg game that the manufacturer is the leader and distributors are the followers. The relationship between the proposed coordination strategy and several factors including the distributor's amount, the distributor's risk aversion and the uncertainties of market demand are analyzed. It indicates that, when there are uncertainties existing in the market demand of the green product, the revenue of each enterprise, the overall revenue and the customer's welfare all decrease; while the increase in the number of distributors and low risk aversion of them are beneficial to the entire GSC and the customer. The conclusions have good guidance for the operational decisions of the green supply chain when the green market is in its initial formation.

Terminal sliding mode tracking control for a class of SISO uncertain nonlinear systems.

PubMed

Chen, Mou; Wu, Qing-Xian; Cui, Rong-Xin

2013-03-01

In this paper, the terminal sliding mode tracking control is proposed for the uncertain single-input and single-output (SISO) nonlinear system with unknown external disturbance. For the unmeasured disturbance of nonlinear systems, terminal sliding mode disturbance observer is presented. The developed disturbance observer can guarantee the disturbance approximation error to converge to zero in the finite time. Based on the output of designed disturbance observer, the terminal sliding mode tracking control is presented for uncertain SISO nonlinear systems. Subsequently, terminal sliding mode tracking control is developed using disturbance observer technique for the uncertain SISO nonlinear system with control singularity and unknown non-symmetric input saturation. The effects of the control singularity and unknown input saturation are combined with the external disturbance which is approximated using the disturbance observer. Under the proposed terminal sliding mode tracking control techniques, the finite time convergence of all closed-loop signals are guaranteed via Lyapunov analysis. Numerical simulation results are given to illustrate the effectiveness of the proposed terminal sliding mode tracking control. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

Gaussian membership functions are most adequate in representing uncertainty in measurements

NASA Technical Reports Server (NTRS)

Kreinovich, V.; Quintana, C.; Reznik, L.

1992-01-01

In rare situations, like fundamental physics, we perform experiments without knowing what their results will be. In the majority of real-life measurement situations, we more or less know beforehand what kind of results we will get. Of course, this is not the precise knowledge of the type 'the result will be between alpha - beta and alpha + beta,' because in this case, we would not need any measurements at all. This is usually a knowledge that is best represented in uncertain terms, like 'perhaps (or 'most likely', etc.) the measured value x is between alpha - beta and alpha + beta.' Traditional statistical methods neglect this additional knowledge and process only the measurement results. So it is desirable to be able to process this uncertain knowledge as well. A natural way to process it is by using fuzzy logic. But, there is a problem; we can use different membership functions to represent the same uncertain statements, and different functions lead to different results. What membership function do we choose? In the present paper, we show that under some reasonable assumptions, Gaussian functions mu(x) = exp(-beta(x(exp 2))) are the most adequate choice of the membership functions for representing uncertainty in measurements. This representation was efficiently used in testing jet engines to airplanes and spaceships.

Molecular dynamics of palmitic acid and lead palmitate in cross-linked linseed oil films: Implications from deuterium magnetic resonance for lead soap formation in traditional oil paintings.

PubMed

Catalano, Jaclyn; Murphy, Anna; Yao, Yao; Zumbulyadis, Nicholas; Centeno, Silvia A; Dybowski, Cecil

2018-02-01

Many oil paintings, dating from the 15th century to the present, are affected by the formation of heavy-metal carboxylates (soaps) that alter the structural integrity and appearance of the works. Through transport phenomena not yet understood, free fatty acids formed from oils used as binders migrate through the paint film and react with heavy-metal ions that are constituents of pigments and/or driers, forming metal carboxylates. The local molecular dynamics of fatty acids and metal carboxylates are factors influencing material transport in these systems. We report temperature-dependent 2 H NMR spectra of palmitic acid and lead palmitate as pure materials, in cross-linked linseed oil films, and in a lead white linseed oil paint film as part of our broader research into metal soap formation. Local dynamics at the α carbon, at the terminal methyl group, and at the middle of the fatty acid chain were observed in specifically deuterated materials. Changes in the dynamic behavior with temperature were observed by the appearance of two species, a solid-like material and a liquid-like material. The relative amounts of the two phases and their deuterium NMR parameters indicate that the amount of liquid-like material and the local dynamics at that site increase with temperature. At the three locations along the chain and at all temperatures, there is a larger percentage of acyl chains of both palmitic acid and lead palmitate that are "mobile" or liquid-like in linseed oil films than there are in the pure materials. However, the percentage of liquid-like species is decreased in a lead white paint film, as compared to a linseed oil matrix. In addition, these experiments indicate that there is a larger percentage of liquid-like acyl chains of palmitic acid than of lead palmitate under identical conditions in these model paint systems. Copyright © 2017 Elsevier Inc. All rights reserved.

A gaseous metal disk around a white dwarf.

PubMed

Gänsicke, B T; Marsh, T R; Southworth, J; Rebassa-Mansergas, A

2006-12-22

The destiny of planetary systems through the late evolution of their host stars is very uncertain. We report a metal-rich gas disk around a moderately hot and young white dwarf. A dynamical model of the double-peaked emission lines constrains the outer disk radius to just 1.2 solar radii. The likely origin of the disk is a tidally disrupted asteroid, which has been destabilized from its initial orbit at a distance of more than 1000 solar radii by the interaction with a relatively massive planetesimal object or a planet. The white dwarf mass of 0.77 solar mass implies that planetary systems may form around high-mass stars.

Efficient algorithms for a class of partitioning problems

NASA Technical Reports Server (NTRS)

Iqbal, M. Ashraf; Bokhari, Shahid H.

1990-01-01

The problem of optimally partitioning the modules of chain- or tree-like tasks over chain-structured or host-satellite multiple computer systems is addressed. This important class of problems includes many signal processing and industrial control applications. Prior research has resulted in a succession of faster exact and approximate algorithms for these problems. Polynomial exact and approximate algorithms are described for this class that are better than any of the previously reported algorithms. The approach is based on a preprocessing step that condenses the given chain or tree structured task into a monotonic chain or tree. The partitioning of this monotonic take can then be carried out using fast search techniques.

The Impact of Model Uncertainty on Spatial Compensation in Active Structural Acoustic Control

NASA Technical Reports Server (NTRS)

Cabell, Randolph H.; Gibbs, Gary P.; Sprofera, Joseph D.; Clark, Robert L.

2004-01-01

Turbulent boundary layer (TBL) noise is considered a primary factor in the interior noise experienced by passengers aboard commercial airliners. There have been numerous investigations of interior noise control devoted to aircraft panels; however, practical realization is a challenge since the physical boundary conditions are uncertain at best. In most prior studies, pinned or clamped boundary conditions have been assumed; however, realistic panels likely display a range of varying boundary conditions between these two limits. Uncertainty in boundary conditions is a challenge for control system designers, both in terms of the compensator implemented and the location of actuators and sensors required to achieve the desired control. The impact of model uncertainties, uncertain boundary conditions in particular, on the selection of actuator and sensor locations for structural acoustic control are considered herein. Results from this research effort indicate that it is possible to optimize the design of actuator and sensor location and aperture, which minimizes the impact of boundary conditions on the desired structural acoustic control.

Sustainable infrastructure system modeling under uncertainties and dynamics

NASA Astrophysics Data System (ADS)

Huang, Yongxi

Infrastructure systems support human activities in transportation, communication, water use, and energy supply. The dissertation research focuses on critical transportation infrastructure and renewable energy infrastructure systems. The goal of the research efforts is to improve the sustainability of the infrastructure systems, with an emphasis on economic viability, system reliability and robustness, and environmental impacts. The research efforts in critical transportation infrastructure concern the development of strategic robust resource allocation strategies in an uncertain decision-making environment, considering both uncertain service availability and accessibility. The study explores the performances of different modeling approaches (i.e., deterministic, stochastic programming, and robust optimization) to reflect various risk preferences. The models are evaluated in a case study of Singapore and results demonstrate that stochastic modeling methods in general offers more robust allocation strategies compared to deterministic approaches in achieving high coverage to critical infrastructures under risks. This general modeling framework can be applied to other emergency service applications, such as, locating medical emergency services. The development of renewable energy infrastructure system development aims to answer the following key research questions: (1) is the renewable energy an economically viable solution? (2) what are the energy distribution and infrastructure system requirements to support such energy supply systems in hedging against potential risks? (3) how does the energy system adapt the dynamics from evolving technology and societal needs in the transition into a renewable energy based society? The study of Renewable Energy System Planning with Risk Management incorporates risk management into its strategic planning of the supply chains. The physical design and operational management are integrated as a whole in seeking mitigations against the potential risks caused by feedstock seasonality and demand uncertainty. Facility spatiality, time variation of feedstock yields, and demand uncertainty are integrated into a two-stage stochastic programming (SP) framework. In the study of Transitional Energy System Modeling under Uncertainty, a multistage stochastic dynamic programming is established to optimize the process of building and operating fuel production facilities during the transition. Dynamics due to the evolving technologies and societal changes and uncertainty due to demand fluctuations are the major issues to be addressed.

Stability analysis for uncertain switched neural networks with time-varying delay.

PubMed

Shen, Wenwen; Zeng, Zhigang; Wang, Leimin

2016-11-01

In this paper, stability for a class of uncertain switched neural networks with time-varying delay is investigated. By exploring the mode-dependent properties of each subsystem, all the subsystems are categorized into stable and unstable ones. Based on Lyapunov-like function method and average dwell time technique, some delay-dependent sufficient conditions are derived to guarantee the exponential stability of considered uncertain switched neural networks. Compared with general results, our proposed approach distinguishes the stable and unstable subsystems rather than viewing all subsystems as being stable, thus getting less conservative criteria. Finally, two numerical examples are provided to show the validity and the advantages of the obtained results. Copyright © 2016 Elsevier Ltd. All rights reserved.

Robust decentralized hybrid adaptive output feedback fuzzy control for a class of large-scale MIMO nonlinear systems and its application to AHS.

PubMed

Huang, Yi-Shao; Liu, Wel-Ping; Wu, Min; Wang, Zheng-Wu

2014-09-01

This paper presents a novel observer-based decentralized hybrid adaptive fuzzy control scheme for a class of large-scale continuous-time multiple-input multiple-output (MIMO) uncertain nonlinear systems whose state variables are unmeasurable. The scheme integrates fuzzy logic systems, state observers, and strictly positive real conditions to deal with three issues in the control of a large-scale MIMO uncertain nonlinear system: algorithm design, controller singularity, and transient response. Then, the design of the hybrid adaptive fuzzy controller is extended to address a general large-scale uncertain nonlinear system. It is shown that the resultant closed-loop large-scale system keeps asymptotically stable and the tracking error converges to zero. The better characteristics of our scheme are demonstrated by simulations. Copyright © 2014. Published by Elsevier Ltd.

Financial characteristics of hospitals purchased by investor-owned chains.

PubMed Central

McCue, M J; Furst, R W

1986-01-01

This article focuses on the preacquisition financial condition of not-for-profit hospitals acquired by investor-owned hospital chains. Financial ratios are used to determine if not-for-profit hospitals acquired by investor-owned hospital systems have common financial characteristics which make them a likely target for a takeover. The results indicate that during the time period studied, investor-owned hospital systems did tend to purchase hospitals with common financial characteristics and that these characteristics provide a reasonable description of a financially distressed hospital. This finding has important consequences for our health care delivery system. PMID:3771232

Reinforcement-Learning-Based Robust Controller Design for Continuous-Time Uncertain Nonlinear Systems Subject to Input Constraints.

PubMed

Liu, Derong; Yang, Xiong; Wang, Ding; Wei, Qinglai

2015-07-01

The design of stabilizing controller for uncertain nonlinear systems with control constraints is a challenging problem. The constrained-input coupled with the inability to identify accurately the uncertainties motivates the design of stabilizing controller based on reinforcement-learning (RL) methods. In this paper, a novel RL-based robust adaptive control algorithm is developed for a class of continuous-time uncertain nonlinear systems subject to input constraints. The robust control problem is converted to the constrained optimal control problem with appropriately selecting value functions for the nominal system. Distinct from typical action-critic dual networks employed in RL, only one critic neural network (NN) is constructed to derive the approximate optimal control. Meanwhile, unlike initial stabilizing control often indispensable in RL, there is no special requirement imposed on the initial control. By utilizing Lyapunov's direct method, the closed-loop optimal control system and the estimated weights of the critic NN are proved to be uniformly ultimately bounded. In addition, the derived approximate optimal control is verified to guarantee the uncertain nonlinear system to be stable in the sense of uniform ultimate boundedness. Two simulation examples are provided to illustrate the effectiveness and applicability of the present approach.

Synthetic Spectral Ananlysis of the Nova-Like Variable KQ Mon

NASA Astrophysics Data System (ADS)

Wolfe, Aaron; Sion, E.

2011-01-01

KQ Mon is classified as a nova-like variable with an uncertain orbital period of 0.128 d. Optical spectra (Zwitter, T. & Munari, U.1994, A&AS, 107, 503) reveal no emission lines but strong Balmer absorption features. High speed flickering has been observed indicative of accretion. IUE spectra reveal deep absorption lines due to C III, C II, Si III, Si IV, C IV, He II but no P Cygni profiles indicative of outflow. Its classification in Ritter and Kolb (2006) as a UX UMa type nova-like is uncertain. We have carried out the first synthetic spectral analysis of the IUE archival spectra of KQ Mon with realistic accretion disk models with vertical structure and high gravity photosphere models. The results of our model atmosphere and model accretion disk analyses are presented. We discuss the properties that we have derived for KQ Mon and compare KQ Mon with other nova-like variables viewed at low inclination. This work was supported in part by NSF grant AST0807892 to Villanova University.

Wave propagation of spectral energy content in a granular chain

NASA Astrophysics Data System (ADS)

Shrivastava, Rohit Kumar; Luding, Stefan

2017-06-01

A mechanical wave is propagation of vibration with transfer of energy and momentum. Understanding the spectral energy characteristics of a propagating wave through disordered granular media can assist in understanding the overall properties of wave propagation through inhomogeneous materials like soil. The study of these properties is aimed at modeling wave propagation for oil, mineral or gas exploration (seismic prospecting) or non-destructive testing of the internal structure of solids. The focus is on the total energy content of a pulse propagating through an idealized one-dimensional discrete particle system like a mass disordered granular chain, which allows understanding the energy attenuation due to disorder since it isolates the longitudinal P-wave from shear or rotational modes. It is observed from the signal that stronger disorder leads to faster attenuation of the signal. An ordered granular chain exhibits ballistic propagation of energy whereas, a disordered granular chain exhibits more diffusive like propagation, which eventually becomes localized at long time periods. For obtaining mean-field macroscopic/continuum properties, ensemble averaging has been used, however, such an ensemble averaged spectral energy response does not resolve multiple scattering, leading to loss of information, indicating the need for a different framework for micro-macro averaging.

Critical behavior of a quantum chain with four-spin interactions in the presence of longitudinal and transverse magnetic fields.

PubMed

Boechat, B; Florencio, J; Saguia, A; de Alcantara Bonfim, O F

2014-03-01

We study the ground-state properties of a spin-1/2 model on a chain containing four-spin Ising-like interactions in the presence of both transverse and longitudinal magnetic fields. We use entanglement entropy and finite-size scaling methods to obtain the phase diagrams of the model. Our numerical calculations reveal a rich variety of phases and the existence of multicritical points in the system. We identify phases with both ferromagnetic and antiferromagnetic orderings. We also find periodically modulated orderings formed by a cluster of like spins followed by another cluster of opposite like spins. The quantum phases in the model are found to be separated by either first- or second-order transition lines.

Adaptive output feedback control of uncertain nonlinear systems using single-hidden-layer neural networks.

PubMed

Hovakimyan, N; Nardi, F; Calise, A; Kim, Nakwan

2002-01-01

We consider adaptive output feedback control of uncertain nonlinear systems, in which both the dynamics and the dimension of the regulated system may be unknown. However, the relative degree of the regulated output is assumed to be known. Given a smooth reference trajectory, the problem is to design a controller that forces the system measurement to track it with bounded errors. The classical approach requires a state observer. Finding a good observer for an uncertain nonlinear system is not an obvious task. We argue that it is sufficient to build an observer for the output tracking error. Ultimate boundedness of the error signals is shown through Lyapunov's direct method. The theoretical results are illustrated in the design of a controller for a fourth-order nonlinear system of relative degree two and a high-bandwidth attitude command system for a model R-50 helicopter.

Magnetization of a quantum spin system induced by a linear polarized laser

NASA Astrophysics Data System (ADS)

Zvyagin, A. A.

2015-08-01

It is shown that a linear polarized laser can cause magnetization of a spin system with magnetic anisotropy, the distinguished axis of which is perpendicular to the polarization of the laser field. In the dynamical regime the magnetization oscillates around the nonzero value determined by the parameters of the system. Oscillations have the frequency of the laser field, modulated by the lower Rabi-like frequencies. In the steady-state regime, for a large time scale greater than the characteristic relaxation time, the Rabi-like oscillations are damped, and the magnetization oscillates with the frequency of the laser field around the value which is determined by the relaxation rate also. Analytic results are presented for the spin-1/2 chain. The most direct manifestation of such a behavior can be observed in spin-1/2 Ising chain materials if the linear polarization of the laser field is chosen to be perpendicular to the Ising axis.

Mutant NDUFS3 subunit of mitochondrial complex I causes Leigh syndrome.

PubMed

Bénit, P; Slama, A; Cartault, F; Giurgea, I; Chretien, D; Lebon, S; Marsac, C; Munnich, A; Rötig, A; Rustin, P

2004-01-01

Respiratory chain complex I deficiency represents a genetically heterogeneous group of diseases resulting from mutations in mitochondrial or nuclear genes. Mutations have been reported in 13 of the 14 subunits encoding the core of complex I (seven mitochondrial and six nuclear genes) and these result in Leigh or Leigh-like syndromes or cardiomyopathy. In this study, a combination of denaturing high performance liquid chromatography and sequence analysis was used to study the NDUFS3 gene in a series of complex I deficient patients. Mutations found in this gene (NADH dehydrogenase iron-sulphur protein 3), coding for the seventh and last subunit of complex I core, were shown to cause late onset Leigh syndrome, optic atrophy, and complex I deficiency. A biochemical diagnosis of complex I deficiency on cultured amniocytes from a later pregnancy was confirmed through the identification of disease causing NDUFS3 mutations in these cells. While mutations in the NDUFS3 gene thus result in Leigh syndrome, a dissimilar clinical phenotype is observed in mutations in the NDUFV2 and NDUFS2 genes, resulting in encephalomyopathy and cardiomyopathy. The reasons for these differences are uncertain.

Self assembled linear polymeric chains with tuneable semiflexibility using isotropic interactions.

PubMed

Abraham, Alex; Chatterji, Apratim

2018-04-21

We propose a two-body spherically symmetric (isotropic) potential such that particles interacting by the potential self-assemble into linear semiflexible polymeric chains without branching. By suitable control of the potential parameters, we can control the persistence length of the polymer and can even introduce a controlled number of branches. Thus we show how to achieve effective directional interactions starting from spherically symmetric potentials. The self-assembled polymers have an exponential distribution of chain lengths akin to what is observed for worm-like micellar systems. On increasing particle density, the polymeric chains self-organize to an ordered line-hexagonal phase where every chain is surrounded by six parallel chains, the transition is first order. On further increase in monomer density, the order is destroyed and we get a branched gel-like phase. This potential can be used to model semi-flexible equilibrium polymers with tunable semiflexibility and excluded volume. The use of the potential is computationally cheap and hence can be used to simulate and probe equilibrium polymer dynamics with long chains. The potential also gives a plausible method of tuning colloidal interactions in experiments such that one can obtain self-assembling polymeric chains made up of colloids and probe polymer dynamics using an optical microscope. Furthermore, we show how a modified potential leads to the observation of an intermediate nematic phase of self-assembled chains in between the low density disordered phase and the line-ordered hexagonal phase.

Self assembled linear polymeric chains with tuneable semiflexibility using isotropic interactions

NASA Astrophysics Data System (ADS)

Abraham, Alex; Chatterji, Apratim

2018-04-01

We propose a two-body spherically symmetric (isotropic) potential such that particles interacting by the potential self-assemble into linear semiflexible polymeric chains without branching. By suitable control of the potential parameters, we can control the persistence length of the polymer and can even introduce a controlled number of branches. Thus we show how to achieve effective directional interactions starting from spherically symmetric potentials. The self-assembled polymers have an exponential distribution of chain lengths akin to what is observed for worm-like micellar systems. On increasing particle density, the polymeric chains self-organize to an ordered line-hexagonal phase where every chain is surrounded by six parallel chains, the transition is first order. On further increase in monomer density, the order is destroyed and we get a branched gel-like phase. This potential can be used to model semi-flexible equilibrium polymers with tunable semiflexibility and excluded volume. The use of the potential is computationally cheap and hence can be used to simulate and probe equilibrium polymer dynamics with long chains. The potential also gives a plausible method of tuning colloidal interactions in experiments such that one can obtain self-assembling polymeric chains made up of colloids and probe polymer dynamics using an optical microscope. Furthermore, we show how a modified potential leads to the observation of an intermediate nematic phase of self-assembled chains in between the low density disordered phase and the line-ordered hexagonal phase.

Primary CNS Nonamyloidogenic Light Chain Deposition Disease: Case Report and Brief Review.

PubMed

Mercado, Juan Jose; Markert, James M; Meador, William; Chapman, Philip; Perry, Arie; Hackney, James R

2017-12-01

The true incidence of light chain deposition disease (LCDD) restricted to the central nervous system (CNS) is unknown. To our knowledge only 7 cases of LCDD restricted to the brain have been previously reported. We herein describe an unusual example. A 44-year-old man presented with a history of ischemic retinopathy in 2004 and left lower extremity hypoesthesia in 2007 that progressed gradually to left-sided weakness and numbness in the 2 years prior to his hospitalization in 2015. A stereotactic brain biopsy was performed, displaying nonspecific hyaline deposits of amorphous "amyloid-like" material involving deep brain white matter and vessels. These were Congo red negative and were accompanied by a sparse lymphoplasmacytic infiltrate. Plasma cells demonstrated kappa light chain class restriction by chromogenic in situ hybridization (CISH). There was patchy reactivity with kappa immunohistochemistry in the amorphous deposits. A diagnosis of light chain deposition disease was made. Subsequent systemic myeloma and lymphoma workups were negative. Previously reported cases have included men and women, spanning the ages of 19 and 72 years, often presenting with hemiparesis, hypoesthesia, or seizures. Deposits have been reported in the cerebrum and cerebellum. T2/FLAIR (fluid attenuation inversion recovery) changes are usual, but lesions may or may not produce contrast enhancement. The light chain deposition may be of kappa or lambda class. Most lesions have been accompanied by local lymphoid and/or plasma cell infiltrates exhibiting light chain restriction of the same class as the deposits. In summary, LCDD limited to the CNS is a rare lesion consisting of deposition of amyloid-like, but Congo red-negative monotypic light chain usually produced by local lymphoplasmacytic infiltrates.

Adaptive control of a quadrotor aerial vehicle with input constraints and uncertain parameters

NASA Astrophysics Data System (ADS)

Tran, Trong-Toan; Ge, Shuzhi Sam; He, Wei

2018-05-01

In this paper, we address the problem of adaptive bounded control for the trajectory tracking of a Quadrotor Aerial Vehicle (QAV) while the input saturations and uncertain parameters with the known bounds are simultaneously taken into account. First, to deal with the underactuated property of the QAV model, we decouple and construct the QAV model as a cascaded structure which consists of two fully actuated subsystems. Second, to handle the input constraints and uncertain parameters, we use a combination of the smooth saturation function and smooth projection operator in the control design. Third, to ensure the stability of the overall system of the QAV, we develop the technique for the cascaded system in the presence of both the input constraints and uncertain parameters. Finally, the region of stability of the closed-loop system is constructed explicitly, and our design ensures the asymptotic convergence of the tracking errors to the origin. The simulation results are provided to illustrate the effectiveness of the proposed method.

Modeling Input Errors to Improve Uncertainty Estimates for Sediment Transport Model Predictions

NASA Astrophysics Data System (ADS)

Jung, J. Y.; Niemann, J. D.; Greimann, B. P.

2016-12-01

Bayesian methods using Markov chain Monte Carlo algorithms have recently been applied to sediment transport models to assess the uncertainty in the model predictions due to the parameter values. Unfortunately, the existing approaches can only attribute overall uncertainty to the parameters. This limitation is critical because no model can produce accurate forecasts if forced with inaccurate input data, even if the model is well founded in physical theory. In this research, an existing Bayesian method is modified to consider the potential errors in input data during the uncertainty evaluation process. The input error is modeled using Gaussian distributions, and the means and standard deviations are treated as uncertain parameters. The proposed approach is tested by coupling it to the Sedimentation and River Hydraulics - One Dimension (SRH-1D) model and simulating a 23-km reach of the Tachia River in Taiwan. The Wu equation in SRH-1D is used for computing the transport capacity for a bed material load of non-cohesive material. Three types of input data are considered uncertain: (1) the input flowrate at the upstream boundary, (2) the water surface elevation at the downstream boundary, and (3) the water surface elevation at a hydraulic structure in the middle of the reach. The benefits of modeling the input errors in the uncertainty analysis are evaluated by comparing the accuracy of the most likely forecast and the coverage of the observed data by the credible intervals to those of the existing method. The results indicate that the internal boundary condition has the largest uncertainty among those considered. Overall, the uncertainty estimates from the new method are notably different from those of the existing method for both the calibration and forecast periods.

An evaluation of consensus techniques for diagnostic interpretation

NASA Astrophysics Data System (ADS)

Sauter, Jake N.; LaBarre, Victoria M.; Furst, Jacob D.; Raicu, Daniela S.

2018-02-01

Learning diagnostic labels from image content has been the standard in computer-aided diagnosis. Most computer-aided diagnosis systems use low-level image features extracted directly from image content to train and test machine learning classifiers for diagnostic label prediction. When the ground truth for the diagnostic labels is not available, reference truth is generated from the experts diagnostic interpretations of the image/region of interest. More specifically, when the label is uncertain, e.g. when multiple experts label an image and their interpretations are different, techniques to handle the label variability are necessary. In this paper, we compare three consensus techniques that are typically used to encode the variability in the experts labeling of the medical data: mean, median and mode, and their effects on simple classifiers that can handle deterministic labels (decision trees) and probabilistic vectors of labels (belief decision trees). Given that the NIH/NCI Lung Image Database Consortium (LIDC) data provides interpretations for lung nodules by up to four radiologists, we leverage the LIDC data to evaluate and compare these consensus approaches when creating computer-aided diagnosis systems for lung nodules. First, low-level image features of nodules are extracted and paired with their radiologists semantic ratings (1= most likely benign, , 5 = most likely malignant); second, machine learning multi-class classifiers that handle deterministic labels (decision trees) and probabilistic vectors of labels (belief decision trees) are built to predict the lung nodules semantic ratings. We show that the mean-based consensus generates the most robust classi- fier overall when compared to the median- and mode-based consensus. Lastly, the results of this study show that, when building CAD systems with uncertain diagnostic interpretation, it is important to evaluate different strategies for encoding and predicting the diagnostic label.

Adaptive fuzzy predictive sliding control of uncertain nonlinear systems with bound-known input delay.

PubMed

Khazaee, Mostafa; Markazi, Amir H D; Omidi, Ehsan

2015-11-01

In this paper, a new Adaptive Fuzzy Predictive Sliding Mode Control (AFP-SMC) is presented for nonlinear systems with uncertain dynamics and unknown input delay. The control unit consists of a fuzzy inference system to approximate the ideal linearization control, together with a switching strategy to compensate for the estimation errors. Also, an adaptive fuzzy predictor is used to estimate the future values of the system states to compensate for the time delay. The adaptation laws are used to tune the controller and predictor parameters, which guarantee the stability based on a Lyapunov-Krasovskii functional. To evaluate the method effectiveness, the simulation and experiment on an overhead crane system are presented. According to the obtained results, AFP-SMC can effectively control the uncertain nonlinear systems, subject to input delays of known bound. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Brachinite-Like Clast in the Kaidun Meteorite: First Report of Primitive Achondrite Material

NASA Technical Reports Server (NTRS)

Higashi, K.; Hasegawa, H.; Mikouchi, T.; Zolensky, M. E.

2017-01-01

Kaidun is a brecciated meteorite containing many different types of meteorites. It is composed of carbonaceous, enstatite, ordinary and R chondrites with smaller amounts of basaltic achondrites, impact melt products and unknown [1, 2]. Because of the multiple components and high abundance of carbonaceous chondrites, the Kaidun parent body was probably a large C-type asteroid in order to have accumulated clasts of many unrelated asteroids, and thus Kaidun contains previously unknown materials[1]. It has been suggested that the Kaidun parent body trawled through different regions of the solar system [3], but the formation of Kaidun meteorite is still uncertain. In this abstract, we report the first discovery of a brachinite-like clast in Kaidun.

Earlinet single calculus chain: new products overview

NASA Astrophysics Data System (ADS)

D'Amico, Giuseppe; Mattis, Ina; Binietoglou, Ioannis; Baars, Holger; Mona, Lucia; Amato, Francesco; Kokkalis, Panos; Rodríguez-Gómez, Alejandro; Soupiona, Ourania; Kalliopi-Artemis, Voudouri

2018-04-01

The Single Calculus Chain (SCC) is an automatic and flexible tool to analyze raw lidar data using EARLINET quality assured retrieval algorithms. It has been already demonstrated the SCC can retrieve reliable aerosol backscatter and extinction coefficient profiles for different lidar systems. In this paper we provide an overview of new SCC products like particle linear depolarization ratio, cloud masking, aerosol layering allowing relevant improvements in the atmospheric aerosol characterization.

Treatment of Acute Renal Failure Secondary to Multiple Myeloma with Chemotherapy and Extended High Cut-Off Hemodialysis

PubMed Central

Hutchison, Colin A.; Bradwell, Arthur R.; Cook, Mark; Basnayake, Kolitha; Basu, Supratik; Harding, Stephen; Hattersley, John; Evans, Neil D.; Chappel, Mike J.; Sampson, Paul; Foggensteiner, Lukas; Adu, Dwomoa; Cockwell, Paul

2009-01-01

Background and objectives: Extended hemodialysis using a high cut-off dialyzer (HCO-HD) removes large quantities of free light chains in patients with multiple myeloma. However, the clinical utility of this method is uncertain. This study assessed the combination of chemotherapy and HCO-HD on serum free light chain concentrations and renal recovery in patients with myeloma kidney (cast nephropathy) and dialysis-dependent acute renal failure. Design, setting, participants, & measurements: An open-label study of the relationship between free light chain levels and clinical outcomes in 19 patients treated with standard chemotherapy regimens and HCO-HD. Results: There were sustained early reductions in serum free light chain concentrations (median 85% [range 50 to 97]) in 13 patients. These 13 patients became dialysis independent at a median of 27 d (range 13 to 120). Six patients had chemotherapy interrupted because of early infections and did not achieve sustained early free light chain reductions; one of these patients recovered renal function (at 105 d) the remaining 5 patients did not recover renal function. Patients who recovered renal function had a significantly improved survival (P < 0.012). Conclusion: In dialysis-dependent acute renal failure secondary to myeloma kidney, patients who received uninterrupted chemotherapy and extended HCO-HD had sustained reductions in serum free light chain concentrations and recovered independent renal function. PMID:19339414

The uncertain response in humans and animals

NASA Technical Reports Server (NTRS)

Smith, J. D.; Shields, W. E.; Schull, J.; Washburn, D. A.; Rumbaugh, D. M. (Principal Investigator)

1997-01-01

There has been no comparative psychological study of uncertainty processes. Accordingly, the present experiments asked whether animals, like humans, escape adaptively when they are uncertain. Human and animal observers were given two primary responses in a visual discrimination task, and the opportunity to escape from some trials into easier ones. In one psychophysical task (using a threshold paradigm), humans escaped selectively the difficult trials that left them uncertain of the stimulus. Two rhesus monkeys (Macaca mulatta) also showed this pattern. In a second psychophysical task (using the method of constant stimuli), some humans showed this pattern but one escaped infrequently and nonoptimally. Monkeys showed equivalent individual differences. The data suggest that escapes by humans and monkeys are interesting cognitive analogs and may reflect controlled decisional processes prompted by the perceptual ambiguity at threshold.

Characterization of topological phases of dimerized Kitaev chain via edge correlation functions

NASA Astrophysics Data System (ADS)

Wang, Yucheng; Miao, Jian-Jian; Jin, Hui-Ke; Chen, Shu

2017-11-01

We study analytically topological properties of a noninteracting modified dimerized Kitaev chain and an exactly solvable interacting dimerized Kitaev chain under open boundary conditions by analyzing two introduced edge correlation functions. The interacting dimerized Kitaev chain at the symmetry point Δ =t and the chemical potential μ =0 can be exactly solved by applying two Jordan-Wigner transformations and a spin rotation, which permits us to calculate the edge correlation functions analytically. We demonstrate that the two edge correlation functions can be used to characterize the trivial, Su-Schrieffer-Heeger-like topological and topological superconductor phases of both the noninteracting and interacting systems and give their phase diagrams.

Bellman Continuum (3rd) International Workshop (13-14 June 1988)

DTIC Science & Technology

1988-06-01

Modelling Uncertain Problem ................. 53 David Bensoussan ,---,>Asymptotic Linearization of Uncertain Multivariable Systems by Sliding Modes...K. Ghosh .-. Robust Model Tracking for a Class of Singularly Perturbed Nonlinear Systems via Composite Control ....... 93 F. Garofalo and L. Glielmo...MODELISATION ET COMMANDE EN ECONOMIE MODELS AND CONTROL POLICIES IN ECONOMICS Qualitative Differential Games : A Viability Approach ............. 117

Distributed control systems with incomplete and uncertain information

NASA Astrophysics Data System (ADS)

Tang, Jingpeng

Scientific and engineering advances in wireless communication, sensors, propulsion, and other areas are rapidly making it possible to develop unmanned air vehicles (UAVs) with sophisticated capabilities. UAVs have come to the forefront as tools for airborne reconnaissance to search for, detect, and destroy enemy targets in relatively complex environments. They potentially reduce risk to human life, are cost effective, and are superior to manned aircraft for certain types of missions. It is desirable for UAVs to have a high level of intelligent autonomy to carry out mission tasks with little external supervision and control. This raises important issues involving tradeoffs between centralized control and the associated potential to optimize mission plans, and decentralized control with great robustness and the potential to adapt to changing conditions. UAV capabilities have been extended several ways through armament (e.g., Hellfire missiles on Predator UAVs), increased endurance and altitude (e.g., Global Hawk), and greater autonomy. Some known barriers to full-scale implementation of UAVs are increased communication and control requirements as well as increased platform and system complexity. One of the key problems is how UAV systems can handle incomplete and uncertain information in dynamic environments. Especially when the system is composed of heterogeneous and distributed UAVs, the overall system complexity is increased under such conditions. Presented through the use of published papers, this dissertation lays the groundwork for the study of methodologies for handling incomplete and uncertain information for distributed control systems. An agent-based simulation framework is built to investigate mathematical approaches (optimization) and emergent intelligence approaches. The first paper provides a mathematical approach for systems of UAVs to handle incomplete and uncertain information. The second paper describes an emergent intelligence approach for UAVs, again in handling incomplete and uncertain information. The third paper combines mathematical and emergent intelligence approaches.

The impact of uncertain threat on affective bias: Individual differences in response to ambiguity.

PubMed

Neta, Maital; Cantelon, Julie; Haga, Zachary; Mahoney, Caroline R; Taylor, Holly A; Davis, F Caroline

2017-12-01

Individuals who operate under highly stressful conditions (e.g., military personnel and first responders) are often faced with the challenge of quickly interpreting ambiguous information in uncertain and threatening environments. When faced with ambiguity, it is likely adaptive to view potentially dangerous stimuli as threatening until contextual information proves otherwise. One laboratory-based paradigm that can be used to simulate uncertain threat is known as threat of shock (TOS), in which participants are told that they might receive mild but unpredictable electric shocks while performing an unrelated task. The uncertainty associated with this potential threat induces a state of emotional arousal that is not overwhelmingly stressful, but has widespread-both adaptive and maladaptive-effects on cognitive and affective function. For example, TOS is thought to enhance aversive processing and abolish positivity bias. Importantly, in certain situations (e.g., when walking home alone at night), this anxiety can promote an adaptive state of heightened vigilance and defense mobilization. In the present study, we used TOS to examine the effects of uncertain threat on valence bias, or the tendency to interpret ambiguous social cues as positive or negative. As predicted, we found that heightened emotional arousal elicited by TOS was associated with an increased tendency to interpret ambiguous cues negatively. Such negative interpretations are likely adaptive in situations in which threat detection is critical for survival and should override an individual's tendency to interpret ambiguity positively in safe contexts. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Adaptive Control for Uncertain Nonlinear Multi-Input Multi-Output Systems

NASA Technical Reports Server (NTRS)

Cao, Chengyu (Inventor); Hovakimyan, Naira (Inventor); Xargay, Enric (Inventor)

2014-01-01

Systems and methods of adaptive control for uncertain nonlinear multi-input multi-output systems in the presence of significant unmatched uncertainty with assured performance are provided. The need for gain-scheduling is eliminated through the use of bandwidth-limited (low-pass) filtering in the control channel, which appropriately attenuates the high frequencies typically appearing in fast adaptation situations and preserves the robustness margins in the presence of fast adaptation.

Effects of Variable Resistance Using Chains on Bench Throw Performance in Trained Rugby Players.

PubMed

Godwin, Mark S; Fernandes, John F T; Twist, Craig

2018-04-01

Godwin, MS, Fernandes, JFT, and Twist, C. Effects of variable resistance using chains on bench throw performance in trained rugby players. J Strength Cond Res 32(4): 950-954, 2018-This study sought to determine the effects of variable resistance using chain resistance on bench throw performance. Eight male rugby union players (19.4 ± 2.3 years, 88.8 ± 6.0 kg, 1RM 105.6 ± 17.0 kg) were recruited from a national league team. In a randomized crossover design, participant's performed 3 bench throws at 45% one repetition maximum (1RM) at a constant load (no chains) or a variable load (30% 1RM constant load and 15% 1RM variable load; chains) with 7 days between conditions. For each repetition, the peak and mean velocity, peak power, peak acceleration, and time to peak velocity were recorded. Differences in peak and mean power were very likely trivial and unclear between the chain and no chain conditions, respectively. Possibly greater peak and likely greater mean bar velocity were accompanied by likely to most likely greater bar velocity between 50 and 400 ms from initiation of bench press in the chain condition compared with the no chain condition. Accordingly, bar acceleration was very likely greater in the chain condition compared with the no chain condition. In conclusion, these results show that the inclusion of chain resistance can acutely enhance several variables in the bench press throw and gives support to this type of training.

Nonequilibrium generalised Langevin equation for the calculation of heat transport properties in model 1D atomic chains coupled to two 3D thermal baths.

PubMed

Ness, H; Stella, L; Lorenz, C D; Kantorovich, L

2017-04-28

We use a generalised Langevin equation scheme to study the thermal transport of low dimensional systems. In this approach, the central classical region is connected to two realistic thermal baths kept at two different temperatures [H. Ness et al., Phys. Rev. B 93, 174303 (2016)]. We consider model Al systems, i.e., one-dimensional atomic chains connected to three-dimensional baths. The thermal transport properties are studied as a function of the chain length N and the temperature difference ΔT between the baths. We calculate the transport properties both in the linear response regime and in the non-linear regime. Two different laws are obtained for the linear conductance versus the length of the chains. For large temperatures (T≳500 K) and temperature differences (ΔT≳500 K), the chains, with N>18 atoms, present a diffusive transport regime with the presence of a temperature gradient across the system. For lower temperatures (T≲500 K) and temperature differences (ΔT≲400 K), a regime similar to the ballistic regime is observed. Such a ballistic-like regime is also obtained for shorter chains (N≤15). Our detailed analysis suggests that the behaviour at higher temperatures and temperature differences is mainly due to anharmonic effects within the long chains.

Beating of grafted chains induced by active Brownian particles

NASA Astrophysics Data System (ADS)

Yang, Qiu-song; Fan, Qing-wei; Shen, Zhuang-lin; Xia, Yi-qi; Tian, Wen-de; Chen, Kang

2018-06-01

We study the interplay between active Brownian particles (ABPs) and a "hairy" surface in two-dimensional geometry. We find that the increase of propelling force leads to and enhances inhomogeneous accumulation of ABPs inside the brush region. Oscillation of chain bundles (beating like cilia) is found in company with the formation and disassembly of a dynamic cluster of ABPs at large propelling forces. Meanwhile chains are stretched and pushed down due to the effective shear force by ABPs. The decrease of the average brush thickness with propelling force reflects the growth of the beating amplitude of chain bundles. Furthermore, the beating phenomenon is investigated in a simple single-chain system. We find that the chain swings regularly with a major oscillatory period, which increases with chain length and decreases with the increase of propelling force. We build a theory to describe the phenomenon and the predictions on the relationship between the period and amplitude for various chain lengths, and propelling forces agree very well with simulation data.

Robust Stabilization of Uncertain Systems Based on Energy Dissipation Concepts

NASA Technical Reports Server (NTRS)

Gupta, Sandeep

1996-01-01

Robust stability conditions obtained through generalization of the notion of energy dissipation in physical systems are discussed in this report. Linear time-invariant (LTI) systems which dissipate energy corresponding to quadratic power functions are characterized in the time-domain and the frequency-domain, in terms of linear matrix inequalities (LMls) and algebraic Riccati equations (ARE's). A novel characterization of strictly dissipative LTI systems is introduced in this report. Sufficient conditions in terms of dissipativity and strict dissipativity are presented for (1) stability of the feedback interconnection of dissipative LTI systems, (2) stability of dissipative LTI systems with memoryless feedback nonlinearities, and (3) quadratic stability of uncertain linear systems. It is demonstrated that the framework of dissipative LTI systems investigated in this report unifies and extends small gain, passivity, and sector conditions for stability. Techniques for selecting power functions for characterization of uncertain plants and robust controller synthesis based on these stability results are introduced. A spring-mass-damper example is used to illustrate the application of these methods for robust controller synthesis.

A robust model predictive control algorithm for uncertain nonlinear systems that guarantees resolvability

NASA Technical Reports Server (NTRS)

Acikmese, Ahmet Behcet; Carson, John M., III

2006-01-01

A robustly stabilizing MPC (model predictive control) algorithm for uncertain nonlinear systems is developed that guarantees resolvability. With resolvability, initial feasibility of the finite-horizon optimal control problem implies future feasibility in a receding-horizon framework. The control consists of two components; (i) feed-forward, and (ii) feedback part. Feed-forward control is obtained by online solution of a finite-horizon optimal control problem for the nominal system dynamics. The feedback control policy is designed off-line based on a bound on the uncertainty in the system model. The entire controller is shown to be robustly stabilizing with a region of attraction composed of initial states for which the finite-horizon optimal control problem is feasible. The controller design for this algorithm is demonstrated on a class of systems with uncertain nonlinear terms that have norm-bounded derivatives and derivatives in polytopes. An illustrative numerical example is also provided.

Chaos synchronization of uncertain chaotic systems using composite nonlinear feedback based integral sliding mode control.

PubMed

Mobayen, Saleh

2018-06-01

This paper proposes a combination of composite nonlinear feedback and integral sliding mode techniques for fast and accurate chaos synchronization of uncertain chaotic systems with Lipschitz nonlinear functions, time-varying delays and disturbances. The composite nonlinear feedback method allows accurate following of the master chaotic system and the integral sliding mode control provides invariance property which rejects the perturbations and preserves the stability of the closed-loop system. Based on the Lyapunov- Krasovskii stability theory and linear matrix inequalities, a novel sufficient condition is offered for the chaos synchronization of uncertain chaotic systems. This method not only guarantees the robustness against perturbations and time-delays, but also eliminates reaching phase and avoids chattering problem. Simulation results demonstrate that the suggested procedure leads to a great control performance. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Branching, Chain Scission, and Solution Stability of Worm-Like Micelles

NASA Astrophysics Data System (ADS)

Beaucage, Greg; Vogtt, Karsten; Jiang, Hanqui

As salt is added to a simple micelle solution such as SDS or SLES, the zero shear rate specific viscosity rises rapidly followed by a maximum and decay. The rapid rise in viscosity is associated with formation of elliptical and extended chain worm-like micelles, WLMs. Entanglement of these long chain micelles leads to the viscoelastic behavior we associate with shampoo and body wash. The plateau and drop in viscosity at high salt concentrations is caused by a special type of topological branching where the branch points have no energy penalty to motion along the chain according to Cates theory. These have some similarity to catenane crosslinks. Predictive dynamic theories for WLMs rely on structural details; the diameter, persistence length, contour length, branch length, segment length between branch points, and mesh size. Further, since the contour length and other large scale features are in kinetic equilibrium, with frequent chain breakage and formation, the thermodynamics of these long chain structures are of interest both in terms of chain scission as well as in terms of the stability of the colloidal solution as a whole. Recent structural studies of WLMs using static neutron scattering based on new scattering models will be presented demonstrating that these input parameters for dynamic models of complex topological systems are quantitatively and directly available. In this context it is important to consider a comparison between dynamic features, for instance entanglement, and their static analogs, chain overlap.

Concepts for the material development of phosphorescent organic materials processable from solution and their application in OLEDs

NASA Astrophysics Data System (ADS)

Janietz, S.; Krueger, H.; Thesen, M.; Salert, B.; Wedel, A.

2014-10-01

One example of organic electronics is the application of polymer based light emitting devices (PLEDs). PLEDs are very attractive for large area and fine-pixel displays, lighting and signage. The polymers are more amenable to solution processing by printing techniques which are favourable for low cost production in large areas. With phosphorescent emitters like Ir-complexes higher quantum efficiencies were obtained than with fluorescent systems, especially if multilayer stack systems with separated charge transport and emitting layers were applied in the case of small molecules. Polymers exhibit the ability to integrate all the active components like the hole-, electron-transport and phosphorescent molecules in only one layer. Here, the active components of a phosphorescent system - triplet emitter, hole- and electron transport molecules - can be linked as a side group to a polystyrene main chain. By varying the molecular structures of the side groups as well as the composition of the side chains with respect to the triplet emitter, hole- and electron transport structure, and by blending with suitable glass-forming, so-called small molecules, brightness, efficiency and lifetime of the produced OLEDs can be optimized. By choosing the triplet emitter, such as iridium complexes, different emission colors can be specially set. Different substituted triazine molecules were introduced as side chain into a polystyrene backbone and applied as electron transport material in PLED blend systems. The influence of alkyl chain lengths of the performance will be discussed. For an optimized blend system with a green emitting phosphorescent Ir-complex efficiencies of 60 cd/A and an lifetime improvement of 66.000 h @ 1000 cd/m2 were achieved.

Complex trophic interactions in kelp forest ecosystems

USGS Publications Warehouse

Estes, J.A.; Danner, E.M.; Doak, D.F.; Konar, B.; Springer, A.M.; Steinberg, P.D.; Tinker, M. Tim; Williams, T.M.

2004-01-01

The distributions and abundances of species and populations change almost continuously. Understanding the processes responsible is perhaps ecology’s most fundamental challenge. Kelp-forest ecosystems in southwest Alaska have undergone several phase shifts between alga- and herbivore-dominated states in recent decades. Overhunting and recovery of sea otters caused the earlier shifts. Studies focusing on these changes demonstrate the importance of top-down forcing processes, a variety of indirect food-web interactions associated with the otter-urchin-kelp trophic cascade, and the role of food-chain length in the coevolution of defense and resistance in plants and their herbivores. This system unexpectedly shifted back to an herbivore-dominated state during the 1990s, because of a sea-otter population collapse that apparently was driven by increased predation by killer whales. Reasons for this change remain uncertain but seem to be linked to the whole-sale collapse of marine mammals in the North Pacific Ocean and southern Bering Sea. We hypothesize that killer whales sequentially "fished down" pinniped and sea-otter populations after their earlier prey, the great whales, were decimated by commercial whaling. The dynamics of kelp forests in southwest Alaska thus appears to have been influenced by an ecological chain reaction that encompassed numerous species and large scales of space and time.

Kernel-based least squares policy iteration for reinforcement learning.

PubMed

Xu, Xin; Hu, Dewen; Lu, Xicheng

2007-07-01

In this paper, we present a kernel-based least squares policy iteration (KLSPI) algorithm for reinforcement learning (RL) in large or continuous state spaces, which can be used to realize adaptive feedback control of uncertain dynamic systems. By using KLSPI, near-optimal control policies can be obtained without much a priori knowledge on dynamic models of control plants. In KLSPI, Mercer kernels are used in the policy evaluation of a policy iteration process, where a new kernel-based least squares temporal-difference algorithm called KLSTD-Q is proposed for efficient policy evaluation. To keep the sparsity and improve the generalization ability of KLSTD-Q solutions, a kernel sparsification procedure based on approximate linear dependency (ALD) is performed. Compared to the previous works on approximate RL methods, KLSPI makes two progresses to eliminate the main difficulties of existing results. One is the better convergence and (near) optimality guarantee by using the KLSTD-Q algorithm for policy evaluation with high precision. The other is the automatic feature selection using the ALD-based kernel sparsification. Therefore, the KLSPI algorithm provides a general RL method with generalization performance and convergence guarantee for large-scale Markov decision problems (MDPs). Experimental results on a typical RL task for a stochastic chain problem demonstrate that KLSPI can consistently achieve better learning efficiency and policy quality than the previous least squares policy iteration (LSPI) algorithm. Furthermore, the KLSPI method was also evaluated on two nonlinear feedback control problems, including a ship heading control problem and the swing up control of a double-link underactuated pendulum called acrobot. Simulation results illustrate that the proposed method can optimize controller performance using little a priori information of uncertain dynamic systems. It is also demonstrated that KLSPI can be applied to online learning control by incorporating an initial controller to ensure online performance.

Building Complex Kondo Impurities by Manipulating Entangled Spin Chains.

PubMed

Choi, Deung-Jang; Robles, Roberto; Yan, Shichao; Burgess, Jacob A J; Rolf-Pissarczyk, Steffen; Gauyacq, Jean-Pierre; Lorente, Nicolás; Ternes, Markus; Loth, Sebastian

2017-10-11

The creation of molecule-like structures in which magnetic atoms interact controllably is full of potential for the study of complex or strongly correlated systems. Here, we create spin chains in which a strongly correlated Kondo state emerges from magnetic coupling of transition-metal atoms. We build chains up to ten atoms in length by placing Fe and Mn atoms on a Cu 2 N surface with a scanning tunneling microscope. The atoms couple antiferromagnetically via superexchange interaction through the nitrogen atom network of the surface. The emergent Kondo resonance is spatially distributed along the chain. Its strength can be controlled by mixing atoms of different transition metal elements and manipulating their spatial distribution. We show that the Kondo screening of the full chain by the electrons of the nonmagnetic substrate depends on the interatomic entanglement of the spins in the chain, demonstrating the prerequisites to build and probe spatially extended strongly correlated nanostructures.

Robust preview control for a class of uncertain discrete-time systems with time-varying delay.

PubMed

Li, Li; Liao, Fucheng

2018-02-01

This paper proposes a concept of robust preview tracking control for uncertain discrete-time systems with time-varying delay. Firstly, a model transformation is employed for an uncertain discrete system with time-varying delay. Then, the auxiliary variables related to the system state and input are introduced to derive an augmented error system that includes future information on the reference signal. This leads to the tracking problem being transformed into a regulator problem. Finally, for the augmented error system, a sufficient condition of asymptotic stability is derived and the preview controller design method is proposed based on the scaled small gain theorem and linear matrix inequality (LMI) technique. The method proposed in this paper not only solves the difficulty problem of applying the difference operator to the time-varying matrices but also simplifies the structure of the augmented error system. The numerical simulation example also illustrates the effectiveness of the results presented in the paper. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Vaccine transport and storage: environmental challenges.

PubMed

Zaffran, M

1996-01-01

This paper describes the current status of the vaccine cold chain that was developed in the 1970s. It then describes the changes that are likely to take place in the next 5 to 10 years and their potential impact on the existing system. For more than 20 years, the cold chain system and vaccine handling rules have been set to the speed of the most fragile of the EPI vaccines namely: Oral Polio Vaccine. This has led to the establishment by WHO of stringent vaccine handling rules and Standard Performance Specifications for cold chain equipment. Major changes are occurring that will impact on immunization programmes: The introduction of Vaccine Vial Monitor (VVM), the prospect of an increase in the stability of OPV and the worldwide ban on refrigeration gases and insulation foaming agents.

Effective production planning for purchased part under long lead time and uncertain demand: MRP Vs demand-driven MRP

NASA Astrophysics Data System (ADS)

Shofa, M. J.; Moeis, A. O.; Restiana, N.

2018-04-01

MRP as a production planning system is appropriate for the deterministic environment. Unfortunately, most production systems such as customer demands are stochastic, so that MRP is inappropriate at the time. Demand-Driven MRP (DDMRP) is new approach for production planning system dealing with demand uncertainty. The objective of this paper is to compare the MRP and DDMRP for purchased part under long lead time and uncertain demand in terms of average inventory levels. The evaluation is conducted through a discrete event simulation with the long lead time and uncertain demand scenarios. The next step is evaluating the performance of DDMRP by comparing the inventory level of DDMRP with MRP. As result, DDMRP is more effective production planning than MRP in terms of average inventory levels.

Adaptive backstepping control of train systems with traction/braking dynamics and uncertain resistive forces

NASA Astrophysics Data System (ADS)

Song, Qi; Song, Y. D.; Cai, Wenchuan

2011-09-01

Although backstepping control design approach has been widely utilised in many practical systems, little effort has been made in applying this useful method to train systems. The main purpose of this paper is to apply this popular control design technique to speed and position tracking control of high-speed trains. By integrating adaptive control with backstepping control, we develop a control scheme that is able to address not only the traction and braking dynamics ignored in most existing methods, but also the uncertain friction and aerodynamic drag forces arisen from uncertain resistance coefficients. As such, the resultant control algorithms are able to achieve high precision train position and speed tracking under varying operation railway conditions, as validated by theoretical analysis and numerical simulations.

Robust linear quadratic designs with respect to parameter uncertainty

NASA Technical Reports Server (NTRS)

Douglas, Joel; Athans, Michael

1992-01-01

The authors derive a linear quadratic regulator (LQR) which is robust to parametric uncertainty by using the overbounding method of I. R. Petersen and C. V. Hollot (1986). The resulting controller is determined from the solution of a single modified Riccati equation. It is shown that, when applied to a structural system, the controller gains add robustness by minimizing the potential energy of uncertain stiffness elements, and minimizing the rate of dissipation of energy through uncertain damping elements. A worst-case disturbance in the direction of the uncertainty is also considered. It is proved that performance robustness has been increased with the robust LQR when compared to a mismatched LQR design where the controller is designed on the nominal system, but applied to the actual uncertain system.

Slow magnetic relaxation in a cobalt magnetic chain.

PubMed

Yang, Chen-I; Chuang, Po-Hsiang; Lu, Kuang-Lieh

2011-04-21

A homospin ladder-like chain, [Co(Hdhq)(OAc)](n) (1; H(2)dhq = 2,3-dihydroxyquinoxaline), shows a single-chain-magnet-like (SCM-like) behavior with the characteristics of frequency dependence of the out-of-phase component in alternating current (ac) magnetic susceptibilities and hysteresis loops. © The Royal Society of Chemistry 2011

How to polymerize ethylene in a highly controlled fashion?

PubMed

Kempe, Rhett

2007-01-01

Very fast, reversible, polyethylene (PE) chain transfer or complex-catalysed "Aufbaureaktion" describes a "living" chain-growing process on a main-group metal or zinc atom; this process is catalysed by an organo-transition-metal or lanthanide complex. PE chains are transferred very fast between the two metal sites and chain growth takes place through ethylene insertion into the transition-metal- or lanthanide-carbon bond-coordinative chain-transfer polymerisation (CCTP). The transferred chains "rest" at the main-group or zinc centre, at which chain-termination processes like beta-H transfer/elimination are of low significance. Such protocols can be used to synthesise very narrowly distributed PE materials (M(w)/M(n)<1.1 up to a molecular weight of about 4000 g mol(-1)) with differently functionalised end groups. Higher molecular-weight polymers can be obtained with a slightly increased M(w)/M(n), since diffusion control and precipitation of the polymers influences the chain-transfer process. Recently, a few transition-metal- or lanthanide-based catalyst systems that catalyse such a highly reversible chain-growing process have been described. They are summarised and compared within this contribution.

Molecular dynamics simulations of steady-state crystal growth and homogeneous nucleation in polyethylene-like polymer

NASA Astrophysics Data System (ADS)

Yamamoto, Takashi

2008-11-01

Molecular mechanisms of crystal growth and homogeneous nucleation from the melt of polyethylene-like linear polymer are investigated by molecular dynamics simulations. The present paper is aimed at extending our previous work with respect to the system size and the boundary condition, thereby enabling detailed studies on the structures of sufficiently large lamellae and fully equilibrated melt. Lamellae of uniform thickness but with marked tapered edges are found to grow at constant velocity from the substrate. Three-dimensional shape of the growing lamellae exhibits peculiar undulation at the growth front, the origin of which is suggested to be the inhomogeneous thickness distribution within the lamellae. Trajectories of chains crystallizing onto the growth front reveal an unexpected pathway for chain folding, where a partially attached chain stem forms a new fold by plunging its head back into a neighboring stem position through slithering snake motions of the chain. Detailed statistics of folds and cilia show that the folds are rather neat and mostly make re-entries into the nearest or the second or third nearest neighboring stem positions, whereas the cilia are generally short but with a small number of longer cilia forming thick amorphous layers. Structure of supercooled melt investigated versus temperature reveals that, at moderate degree of supercooling, the overall chain conformation remains Gaussian random coil but the persistent length of chains increases monotonically with increasing supercooling. Exceptions are at the largest supercooling where homogeneous nucleation takes place; usual melt structure becomes rapidly unstable and emerges many crystallites of random orientations. During early 10-20ns after the quench, density of melt, radius of gyration of chains, and fraction of kinked bonds show marked alterations. These structural changes are highly cooperative and are considered simply due to the emergence of many embryonic crystals in the melt. Conformations of the chains forming nuclei are also traced to reveal that the homogeneous nuclei are fringed micelle like aggregates of chains, but the chains as a whole have folded conformations, which are similar to those reported in previous simulations on a single polyethylene in a vacuum.

Dimension and bridging ligand effects on Mo-mediated catalytic transformation of dinitrogen to ammonia: Chain-like extended models of Nishibayashi’s catalyst

DOE PAGES

Sheng, Xiao -Lan; Batista, Enrique Ricardo; Duan, Yi -Xiang; ...

2016-11-01

Previous studies suggested that in Nishibayashi’s homogenous catalytic systems based on molybdenum (Mo) complexes, the bimetallic structure facilitated dinitrogen to ammonia conversion in comparison to the corresponding monometallic complexes, likely due to the through-bond interactions between the two Mo centers. However, more detailed model systems are necessary to support this bimetallic hypothesis, and to elucidate the multi-metallic effects on the catalytic mechanism. In this work, we computationally examined the effects of dimension as well as the types of bridging ligands on the catalytic activities of molybdenum-dinitrogen complexes by using a set of extended model systems based on Nishibayashi’s bimetallic structure.more » The polynuclear chains containing four ([Mo] 4) or more Mo centers were found to drastically enhance the catalytic performance by comparing with both the monometallic and bimetallic complexes. Carbide ([:C≡C:] 2–) was found to be a more effective bridging ligand than N 2 in terms of electronic charges dispersion between metal centers thereby facilitating reactions in the catalytic cycle. Furthermore, the mechanistic modelling suggests that in principle, more efficient catalytic system for N 2 to NH 3 transformation might be obtained by extending the polynuclear chain to a proper size in combination with an effective bridging ligand for charge dispersion.« less

Dimension and bridging ligand effects on Mo-mediated catalytic transformation of dinitrogen to ammonia: Chain-like extended models of Nishibayashi’s catalyst

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

Sheng, Xiao -Lan; Batista, Enrique Ricardo; Duan, Yi -Xiang

Previous studies suggested that in Nishibayashi’s homogenous catalytic systems based on molybdenum (Mo) complexes, the bimetallic structure facilitated dinitrogen to ammonia conversion in comparison to the corresponding monometallic complexes, likely due to the through-bond interactions between the two Mo centers. However, more detailed model systems are necessary to support this bimetallic hypothesis, and to elucidate the multi-metallic effects on the catalytic mechanism. In this work, we computationally examined the effects of dimension as well as the types of bridging ligands on the catalytic activities of molybdenum-dinitrogen complexes by using a set of extended model systems based on Nishibayashi’s bimetallic structure.more » The polynuclear chains containing four ([Mo] 4) or more Mo centers were found to drastically enhance the catalytic performance by comparing with both the monometallic and bimetallic complexes. Carbide ([:C≡C:] 2–) was found to be a more effective bridging ligand than N 2 in terms of electronic charges dispersion between metal centers thereby facilitating reactions in the catalytic cycle. Furthermore, the mechanistic modelling suggests that in principle, more efficient catalytic system for N 2 to NH 3 transformation might be obtained by extending the polynuclear chain to a proper size in combination with an effective bridging ligand for charge dispersion.« less

Identification and characterization of a novel ISG15-ubiquitin mixed chain and its role in regulating protein homeostasis

PubMed Central

Fan, Jun-Bao; Arimoto, Kei-lchiro; Motamedchaboki, Khatereh; Yan, Ming; Wolf, Dieter A.; Zhang, Dong-Er

2015-01-01

As a ubiquitin-like modifier, ISG15 is conjugated to many cellular proteins in a process termed protein ISGylation. However, the crosstalk between protein ISGylation and the ubiquitin proteasome system is not fully understood. Here, we report that cellular ubiquitin is a substrate of ISG15 and Lys 29 on ubiquitin is the major ISG15 acceptor site. Using a model substrate, we demonstrate that ISG15 can modify ubiquitin, which is immobilized on its substrate, to form ISG15-ubiquitin mixed chains. Furthermore, our results indicate that ISG15-ubiquitin mixed chains do not serve as degradation signals for a ubiquitin fusion degradation substrate. Accordingly, an ISG15-ubiquitin fusion protein, which mimics an ISG15-ubiquitin mixed chain, negatively regulates cellular turnover of ubiquitylated proteins. In addition, ISG15-ubiquitin mixed chains, which are detectable on endogenously ubiquitylated proteins, dampen cellular turnover of these proteins. Thus, our studies unveil an unanticipated interplay between two protein modification systems and highlight its role in coordinating protein homeostasis. PMID:26226047

Historical changes in the Mississippi-Alabama barrier-island chain and the roles of extreme storms, sea level, and human activities

USGS Publications Warehouse

Morton, R.A.

2008-01-01

Barrier-island chains worldwide are undergoing substantial changes, and their futures remain uncertain. An historical analysis of a barrier-island chain in the north-central Gulf of Mexico shows that the Mississippi barriers are undergoing rapid systematic land loss and translocation associated with: (1) unequal lateral transfer of sand related to greater updrift erosion compared to downdrift deposition; (2) barrier narrowing resulting from simultaneous erosion of shores along the Gulf and Mississippi Sound; and (3) barrier segmentation related to storm breaching. Dauphin Island, Alabama, is also losing land for some of the same reasons as it gradually migrates landward. The principal causes of land loss are frequent intense storms, a relative rise in sea level, and a sediment-budget deficit. Considering the predicted trends for storms and sea level related to global warming, it is certain that the Mississippi-Alabama (MS-AL) barrier islands will continue to lose land area at a rapid rate unless the trend of at least one causal factor reverses. Historical land-loss trends and engineering records show that progressive increases in land-loss rate correlate with nearly simultaneous deepening of channels dredged across the outer bars of the three tidal inlets maintained for deep-draft shipping. This correlation indicates that channel-maintenance activities along the MS-AL barriers have impacted the sediment budget by disrupting the alongshore sediment transport system and progressively reducing sand supply. Direct management of this causal factor can be accomplished by strategically placing dredged sediment where adjacent barrier-island shores will receive it for island nourishment and rebuilding.

Performance improvement: an active life cycle product management

NASA Astrophysics Data System (ADS)

Cucchiella, Federica; Gastaldi, Massimo; Lenny Koh, S. C.

2010-03-01

The management of the supply chain has gained importance in many manufacturing firms. Operational flexibility can be considered a crucial weapon to increase competitiveness in a turbulent marketplace. It reflects the ability of a firm to properly and rapidly respond to a variable and dynamic environment. For the firm operating in a fashion sector, the management of the supply chain is even more complex because the product life cycle is shorter than that of the firm operating in a non-fashion sector. The increase of firm flexibility level can be reached through the application of the real option theory inside the firm network. In fact, real option may increase the project value by allowing managers to more efficiently direct the production. The real option application usually analysed in literature does not take into account that the demands of products are well-defined by the product life cycle. Working on a fashion sector, the life cycle pattern is even more relevant because of an expected demand that grows according to a constant rate that does not capture the demand dynamics of the underlying fashion goods. Thus, the primary research objective of this article is to develop a model useful for the management of investments in a supply chain operating in a fashion sector where the system complexity is increased by the low level of unpredictability and stability that is proper of the mood phenomenon. Moreover, unlike the traditional model, a real option framework is presented here that considers fashion product characterised by uncertain stages of the production cycle.

Linear island and seamount chains, aseismic ridges and intraplate volcanism: Results from DSDP

USGS Publications Warehouse

Clague, David A.

1981-01-01

The Deep Sea Drilling Project drilled a substantial number of sites that bear on the origin of linear island and seamount chains, aseismic ridges and other more regional expressions of intraplate volcanism. Drilling in the Emperor Seamounts during Leg 55 was particularly successful. Results from this leg include: 1) the volcanoes of the Hawaiian-Emperor chain continue to increase in age away from Kilauea as predicted. 2) Suiko Seamount formed at a paleolatitide of 26.9±3.5°N, 7° north of present-day Hawaii, but far south of its present latitude of 44.8°N. 3) the volcanic rock types recovered include hawaiite, mugearite, alkalic basalt and tholeiitic basalt in the sequence and relative volume expected for Hawaiian volcanoes. 4) the tholeiitic and alkalic basalts recovered are geochemically similar to those in the Hawaiian Islands, only the ratio of 87Sr/86Sr appears to change through time. All the lavas appear to be derived from a source that has small-scale heterogeneities, but is homogeneous on a large scale. 4) The Emperor Seamounts were once volcanic islands that underwent subaerial and shallow marine erosion, and deposition of shallow-water biogenic carbonate sediments that capped all or most of each volcano.Drilling in other regions has yielded less conclusive results. For example, it is uncertain if the Line Islands are an age progressive chain (hot-spot trace) or result from some other type of intraplate volcanism. The mid-Pacific Mountains also show evidence of originating from a regional episode of volcanism in the mid-Cretaceous. Drilling in the Nauru Basin encountered a voluminous mid-Cretaceous volcanic flow-sill complex that overlies Jurassic magnetic anomalies, yet is composed of depleted tholeiite. In the Indian Ocean, drilling on the Ninety-East Ridge established that it 1) is volcanic in origin; 2) is older to the north; 3) formed in shallow water, and 4) formed further south and has moved northward. It appears that the Ninety-East Ridge, like the Hawaiian-Emperor chain, is a hot spot trace. In the Atlantic Ocean, drilling on the Iceland-Faeroe Ridge and the Rio Grande Rise-Walvis Ridge suggests that all these aseismic ridges are hot spot traces generated by the Iceland and Tristan de Cunha hot-spots.

Uncertainty quantification for discrimination of nuclear events as violations of the comprehensive nuclear-test-ban treaty.

PubMed

Sloan, Jamison; Sun, Yunwei; Carrigan, Charles

2016-05-01

Enforcement of the Comprehensive Nuclear Test Ban Treaty (CTBT) will involve monitoring for radiologic indicators of underground nuclear explosions (UNEs). A UNE produces a variety of radioisotopes which then decay through connected radionuclide chains. A particular species of interest is xenon, namely the four isotopes (131m)Xe, (133m)Xe, (133)Xe, and (135)Xe. Due to their half lives, some of these isotopes can exist in the subsurface for more than 100 days. This convenient timescale, combined with modern detection capabilities, makes the xenon family a desirable candidate for UNE detection. Ratios of these isotopes as a function of time have been studied in the past for distinguishing nuclear explosions from civilian nuclear applications. However, the initial yields from UNEs have been treated as fixed values. In reality, these independent yields are uncertain to a large degree. This study quantifies the uncertainty in xenon ratios as a result of these uncertain initial conditions to better bound the values that xenon ratios can assume. We have successfully used a combination of analytical and sampling based statistical methods to reliably bound xenon isotopic ratios. We have also conducted a sensitivity analysis and found that xenon isotopic ratios are primarily sensitive to only a few of many uncertain initial conditions. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Efficiency of the human observer detecting random signals in random backgrounds

PubMed Central

Park, Subok; Clarkson, Eric; Kupinski, Matthew A.; Barrett, Harrison H.

2008-01-01

The efficiencies of the human observer and the channelized-Hotelling observer relative to the ideal observer for signal-detection tasks are discussed. Both signal-known-exactly (SKE) tasks and signal-known-statistically (SKS) tasks are considered. Signal location is uncertain for the SKS tasks, and lumpy backgrounds are used for background uncertainty in both cases. Markov chain Monte Carlo methods are employed to determine ideal-observer performance on the detection tasks. Psychophysical studies are conducted to compute human-observer performance on the same tasks. Efficiency is computed as the squared ratio of the detectabilities of the observer of interest to the ideal observer. Human efficiencies are approximately 2.1% and 24%, respectively, for the SKE and SKS tasks. The results imply that human observers are not affected as much as the ideal observer by signal-location uncertainty even though the ideal observer outperforms the human observer for both tasks. Three different simplified pinhole imaging systems are simulated, and the humans and the model observers rank the systems in the same order for both the SKE and the SKS tasks. PMID:15669610

Molecular dynamics study of linear and comb-like polyelectrolytes in aqueous solution: effect of Ca2+ ions

NASA Astrophysics Data System (ADS)

Tong, Kefeng; Song, Xingfu; Sun, Shuying; Xu, Yanxia; Yu, Jianguo

2014-08-01

All-atom molecular dynamics simulations were employed to provide microscopic mechanism for the salt tolerance of polyelectrolytes dispersants. The conformational variation of polyelectrolytes and interactions between COO- groups and counterions/water molecules were also studied via radius of gyration and pair correlations functions. Sodium polyacrylate (NaPA) and sodium salts of poly(acrylic acid)-poly(ethylene oxide) (NaPA-PEO) were selected as the representative linear and comb-like polyelectrolyte, respectively. The results show that Ca2+ ions interact with COO- groups much stronger than Na+ ions and can bring ion-bridging interaction between intermolecular COO- groups in the NaPA systems. While in the NaPA-PEO systems, the introduced PEO side chains can prevent backbone chains from ion-bridging interactions and weaken the conformational changes. The present results can help in selecting and designing new-type efficient polyelectrolyte dispersants with good salt tolerance.

Superdiffusive transport and energy localization in disordered granular crystals

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

Martinez, Alejandro J.; Kevrekidis, Panagiotis G.; Porter, Mason A.

We study the spreading of initially localized excitations in one-dimensional disordered granular crystals. We thereby investigate localization phenomena in strongly nonlinear systems, which we demonstrate to be fundamentally different from localization in linear and weakly nonlinear systems. We conduct a thorough comparison of wave dynamics in chains with three different types of disorder: an uncorrelated (Anderson-like) disorder and two types of correlated disorders (which are produced by random dimer arrangements), and for two families of initial conditions: displacement perturbations and velocity perturbations. We find for strongly precompressed (i.e., weakly nonlinear) chains that the dynamics strongly depends on the initial condition.more » Furthermore, for displacement perturbations, the long-time asymptotic behavior of the second moment m ~2 has oscillations that depend on the type of disorder, with a complex trend that is markedly different from a power law and which is particularly evident for an Anderson-like disorder.« less

Superdiffusive transport and energy localization in disordered granular crystals

DOE PAGES

Martinez, Alejandro J.; Kevrekidis, Panagiotis G.; Porter, Mason A.

2016-02-12

We study the spreading of initially localized excitations in one-dimensional disordered granular crystals. We thereby investigate localization phenomena in strongly nonlinear systems, which we demonstrate to be fundamentally different from localization in linear and weakly nonlinear systems. We conduct a thorough comparison of wave dynamics in chains with three different types of disorder: an uncorrelated (Anderson-like) disorder and two types of correlated disorders (which are produced by random dimer arrangements), and for two families of initial conditions: displacement perturbations and velocity perturbations. We find for strongly precompressed (i.e., weakly nonlinear) chains that the dynamics strongly depends on the initial condition.more » Furthermore, for displacement perturbations, the long-time asymptotic behavior of the second moment m ~2 has oscillations that depend on the type of disorder, with a complex trend that is markedly different from a power law and which is particularly evident for an Anderson-like disorder.« less

Feature inference with uncertain categorization: Re-assessing Anderson's rational model.

PubMed

Konovalova, Elizaveta; Le Mens, Gaël

2017-09-18

A key function of categories is to help predictions about unobserved features of objects. At the same time, humans are often in situations where the categories of the objects they perceive are uncertain. In an influential paper, Anderson (Psychological Review, 98(3), 409-429, 1991) proposed a rational model for feature inferences with uncertain categorization. A crucial feature of this model is the conditional independence assumption-it assumes that the within category feature correlation is zero. In prior research, this model has been found to provide a poor fit to participants' inferences. This evidence is restricted to task environments inconsistent with the conditional independence assumption. Currently available evidence thus provides little information about how this model would fit participants' inferences in a setting with conditional independence. In four experiments based on a novel paradigm and one experiment based on an existing paradigm, we assess the performance of Anderson's model under conditional independence. We find that this model predicts participants' inferences better than competing models. One model assumes that inferences are based on just the most likely category. The second model is insensitive to categories but sensitive to overall feature correlation. The performance of Anderson's model is evidence that inferences were influenced not only by the more likely category but also by the other candidate category. Our findings suggest that a version of Anderson's model which relaxes the conditional independence assumption will likely perform well in environments characterized by within-category feature correlation.

A shark antibody heavy chain encoded by a nonsomatically rearranged VDJ is preferentially expressed in early development and is convergent with mammalian IgG.

PubMed

Rumfelt, L L; Avila, D; Diaz, M; Bartl, S; McKinney, E C; Flajnik, M F

2001-02-13

In most vertebrate embryos and neonates studied to date unique antigen receptors (antibodies and T cell receptors) are expressed that possess a limited immune repertoire. We have isolated a subclass of IgM, IgM(1gj), from the nurse shark Ginglymostoma cirratum that is preferentially expressed in neonates. The variable (V) region gene encoding the heavy (H) chain underwent V-D-J rearrangement in germ cells ("germline-joined"). Such H chain V genes were discovered over 10 years ago in sharks but until now were not shown to be expressed at appreciable levels; we find expression of H(1gj) in primary and secondary lymphoid tissues early in life, but in adults only in primary lymphoid tissue, which is identified in this work as the epigonal organ. H(1gj) chain associates covalently with light (L) chains and is most similar in sequence to IgM H chains, but like mammalian IgG has three rather than the four IgM constant domains; deletion of the ancestral IgM C2 domain thus defines both IgG and IgM(1gj). Because sharks are the members of the oldest vertebrate class known to possess antibodies, unique or specialized antibodies expressed early in ontogeny in sharks and other vertebrates were likely present at the inception of the adaptive immune system.

Why do verification and validation?

DOE PAGES

Hu, Kenneth T.; Paez, Thomas L.

2016-02-19

In this discussion paper, we explore different ways to assess the value of verification and validation (V&V) of engineering models. We first present a literature review on the value of V&V and then use value chains and decision trees to show how value can be assessed from a decision maker's perspective. In this context, the value is what the decision maker is willing to pay for V&V analysis with the understanding that the V&V results are uncertain. As a result, the 2014 Sandia V&V Challenge Workshop is used to illustrate these ideas.

Shark complement: an assessment.

PubMed

Smith, S L

1998-12-01

The classical (CCP) and alternative (ACP) pathways of complement activation have been established for the nurse shark (Ginglymostoma cirratum). The isolation of a cDNA clone encoding a mannan-binding protein-associated serine protease (MASP)-1-like protein from the Japanese dogfish (Triakis scyllia) suggests the presence of a lectin pathway. The CCP consists of six functionally distinct components: C1n, C2n, C3n, C4n, C8n and C9n, and is activated by immune complexes in the presence of Ca++ and Mg++ ions. The ACP is antibody independent, requiring Mg++ ions and a heat-labile 90 kDa factor B-like protein for activity. Proteins considered homologues of C1q, C3 and C4 (C2n) of the mammalian complement system have been isolated from nurse shark serum. Shark C1q is composed of at least two chain types each showing 50% identity to human C1q chains A and B. Partial sequence of the globular domain of one of the chains shows it to be C1q-like rather than like mannan-binding protein. N-terminal amino acid sequences of the alpha and beta chain of shark C3 and C4 molecules show significant identity with corresponding human C3 and C4 chains. A sequence representing shark C4 gamma chain, shows little similarity to human C4 gamma chain. The terminal shark components C8n and C9n are functional analogues of mammalian C8 and C9. Anaphylatoxin activity has been demonstrated in activated shark serum, and porcine C5a desArg induces shark leucocyte chemotaxis. The deduced amino acid sequence of a partial C3 cDNA clone from the nurse shark shows 50%, 30% and 24% homology with the corresponding region of mammalian C3, C4 and alpha 2-macroglobulin. Deduced amino acid sequence data from partial Bf/C2 cDNA clones, two from the nurse shark and one from the Japanese dogfish, suggest that at least one species of elasmobranch has two distinct Bf/C2 genes.

Control of Uncertain Systems under Constraints: Switching Horizon Predictive Control of Persistently Disturbed Input-Saturated Plants

DTIC Science & Technology

2006-12-01

on at any time from a family of candidate feedback-gains so as to control a discrete- time input-saturated LTI system possibly subject to persistent... times robustness Mosca, E. (2006) Control of Uncertain Systems under Constraints: Switching Horizon Predictive Control of Persistently Disturbed...feedback controls u = f(x̂) (3) so as to ensure, under suitable conditions, stability in the noiseless case as well as finite l∞-induced gain of the

Light Scattering Study of Mixed Micelles Made from Elastin-Like Polypeptide Linear Chains and Trimers

NASA Astrophysics Data System (ADS)

Terrano, Daniel; Tsuper, Ilona; Maraschky, Adam; Holland, Nolan; Streletzky, Kiril

Temperature sensitive nanoparticles were generated from a construct (H20F) of three chains of elastin-like polypeptides (ELP) linked to a negatively charged foldon domain. This ELP system was mixed at different ratios with linear chains of ELP (H40L) which lacks the foldon domain. The mixed system is soluble at room temperature and at a transition temperature (Tt) will form swollen micelles with the hydrophobic linear chains hidden inside. This system was studied using depolarized dynamic light scattering (DDLS) and static light scattering (SLS) to determine the size, shape, and internal structure of the mixed micelles. The mixed micelle in equal parts of H20F and H40L show a constant apparent hydrodynamic radius of 40-45 nm at the concentration window from 25:25 to 60:60 uM (1:1 ratio). At a fixed 50 uM concentration of the H20F, varying H40L concentration from 5 to 80 uM resulted in a linear growth in the hydrodynamic radius from about 11 to about 62 nm, along with a 1000-fold increase in VH signal. A possible simple model explaining the growth of the swollen micelles is considered. Lastly, the VH signal can indicate elongation in the geometry of the particle or could possibly be a result from anisotropic properties from the core of the micelle. SLS was used to study the molecular weight, and the radius of gyration of the micelle to help identify the structure and morphology of mixed micelles and the tangible cause of the VH signal.

Measuring the excitations in a new S  =  1/2 quantum spin chain material with competing interactions

NASA Astrophysics Data System (ADS)

Rule, K. C.; Mole, R. A.; Zanardo, J.; Krause-Heuer, A.; Darwish, T.; Lerch, M.; Yu, D.

2018-05-01

Recently a new one-dimensional (1D) quantum spin chain system has been reported: catena-dichloro(2-Cl-3Mpy)copper(II), (where 2-Cl-3Mpy=2-chloro-3-methylpyridine). Preliminary calculations and bulk magnetic property measurements indicate that this system does not undergo magnetic ordering down to 1.8 K and is a prime candidate for investigating frustration in a J 1/J 2 system (where the nearest neighbour interactions, J 1, are ferromagnetic and the next nearest neighbour interactions, J 2, are antiferromagnetic). Calculations predicted three possible magnetic interaction strengths for J 1 below 6 meV depending on the orientation of the ligand. For one of the predicted J 1 values, the existence of a quantum critical point is implied. A deuterated sample of catena-dichloro(2-Cl-3Mpy)copper(II) was synthesised and the excitations measured using inelastic neutron scattering. Scattering indicated the most likely scenario involves spin-chains where each chain consists of only one of the three possible magnetic excitations in this material, rather than the completely random array of exchange interactions within each chain as predicted by Herringer et al (2014 Chem. Eur. J. 20 8355–62). This indicates the possibility of tuning the chemical structure to favour a system which may exhibit a quantum critical point.

Measuring the excitations in a new S  =  1/2 quantum spin chain material with competing interactions.

PubMed

Rule, K C; Mole, R A; Zanardo, J; Krause-Heuer, A; Darwish, T; Lerch, M; Yu, D

2018-05-31

Recently a new one-dimensional (1D) quantum spin chain system has been reported: catena-dichloro(2-Cl-3Mpy)copper(II), (where 2-Cl-3Mpy=2-chloro-3-methylpyridine). Preliminary calculations and bulk magnetic property measurements indicate that this system does not undergo magnetic ordering down to 1.8 K and is a prime candidate for investigating frustration in a J 1 /J 2 system (where the nearest neighbour interactions, J 1 , are ferromagnetic and the next nearest neighbour interactions, J 2 , are antiferromagnetic). Calculations predicted three possible magnetic interaction strengths for J 1 below 6 meV depending on the orientation of the ligand. For one of the predicted J 1 values, the existence of a quantum critical point is implied. A deuterated sample of catena-dichloro(2-Cl-3Mpy)copper(II) was synthesised and the excitations measured using inelastic neutron scattering. Scattering indicated the most likely scenario involves spin-chains where each chain consists of only one of the three possible magnetic excitations in this material, rather than the completely random array of exchange interactions within each chain as predicted by Herringer et al (2014 Chem. Eur. J. 20 8355-62). This indicates the possibility of tuning the chemical structure to favour a system which may exhibit a quantum critical point.

Influence of the molecular architecture on the adsorption onto solid surfaces: comb-like polymers.

PubMed

Guzmán, Eduardo; Ortega, Francisco; Prolongo, Margarita G; Starov, Victor M; Rubio, Ramón G

2011-09-28

The processes of adsorption of grafted copolymers onto negatively charged surfaces were studied using a dissipative quartz crystal microbalance (D-QCM) and ellipsometry. The control parameters in the study of the adsorption are the existence or absence on the molecular architecture of grafted polyethyleneglycol (PEG) chains with different lengths and the chemical nature of the main chain, poly(allylamine) (PAH) or poly(L-lysine) (PLL). It was found out that the adsorption kinetics of the polymers showed a complex behavior. The total adsorbed amount depends on the architecture of the polymer chains (length of the PEG chains), on the polymer concentration and on the chemical nature of the main chain. The comparison of the thicknesses of the adsorbed layers obtained from D-QCM and from ellipsometry allowed calculation of the water content of the layers that is intimately related to the grafting length. The analysis of D-QCM results also provides information about the shear modulus of the layers, whose values have been found to be typical of a rubber-like polymer system. It is shown that the adsorption of polymers with a charged backbone is not driven exclusively by the electrostatic interactions, but the entropic contributions as a result of the trapping of water in the layer structure are of fundamental importance.

Finding the Missing Physics: Simulating Polydisperse Polymer Melts

NASA Astrophysics Data System (ADS)

Rorrer, Nichoals; Dorgan, John

2014-03-01

A Monte Carlo algorithm has been developed to model polydisperse polymer melts. For the first time, this enables the specification of a predetermined molecular weight distribution for lattice based simulations. It is demonstrated how to map an arbitrary probability distributions onto a discrete number of chains residing on an fcc lattice. The resulting algorithm is able to simulate a wide variety of behaviors for polydisperse systems including confinement effects, shear flow, and parabolic flow. The dynamic version of the algorithm accurately captures Rouse dynamics for short polymer chains, and reptation-like dynamics for longer chain lengths.1 When polydispersity is introduced, smaller Rouse times and broadened the transition between different scaling regimes are observed. Rouse times also decrease under confinement for both polydisperse and monodisperse systems and chain length dependent migration effects are observed. The steady-state version of the algorithm enables the simulation of flow and when polydisperse systems are subject to parabolic (Poiseulle) flow, a migration phenomenon based on chain length is again present. These and other phenomena highlight the importance of including polydispersity in obtaining physically realistic simulations of polymeric melts. 1. Dorgan, J.R.; Rorrer, N.A.; Maupin, C.M., Macromolecules 2012, 45(21), 8833-8840. Work funded by the Fluid Dynamics program of the National Science Foundation under grant CBET-1067707.

Interlocked molecules: Moving into another dimension

NASA Astrophysics Data System (ADS)

Fournel-Marotte, Karine; Coutrot, Frédéric

2017-02-01

Molecular daisy-chain structures are typically made up of two interlocked components and can exhibit muscle-like contraction and extension in one dimension. Zinc-based multicomponent systems that can operate in two and three dimensions have now been designed and synthesized.

The Critical Role of Supply Chains in Preventing Human Immunodeficiency Virus Drug Resistance in Low- and Middle-Income Settings.

PubMed

Minior, Thomas; Douglas, Meaghan; Edgil, Dianna; Srivastava, Meena; Crowley, John; Firth, Jacqueline; Lapidos-Salaiz, Ilana; Williams, Jason; Lee, Lana

2017-12-01

The functioning of the supply chain may be a driving factor behind the development of human immunodeficiency virus (HIV) drug resistance (HIVDR) in many low- and middle-income countries (LMICs). Additionally, the effectiveness of supply chains will likely impact the scale-up of both viral-load monitoring and HIVDR testing. This article describes the complexities of global supply chains relevant for LMICs and presents early data on stock-outs and drug substitutions in several countries supported by the US President's Emergency Plan for AIDS Relief. Supply chain systems will need to be strengthened to minimize interruptions as new antiretroviral therapy regimens are introduced and to facilitate adoption of new laboratory technologies. Published by Oxford University Press for the Infectious Diseases Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Pregnant patients' risk perception of prenatal test results with uncertain fetal clinical significance: ultrasound versus advanced genetic testing.

PubMed

Richards, Elliott G; Sangi-Haghpeykar, Haleh; McGuire, Amy L; Van den Veyver, Ignatia B; Fruhman, Gary

2015-12-01

A common concern of utilizing prenatal advanced genetic testing is that a result of uncertain clinical significance will increase patient anxiety. However, prenatal ultrasound may also yield findings of uncertain significance, such as 'soft markers' for fetal aneuploidy, or findings with variable prognosis, such as mild ventriculomegaly. In this study we compared risk perception following uncertain test results from each modality. A single survey with repeated measures design was administered to 133 pregnant women. It included 'intolerance of uncertainty' questions, two hypothetical scenarios involving prenatal ultrasound or advanced genetic testing, and response questions. The primary outcome was risk perception score. Risk perception did not vary significantly between ultrasound and genetic scenarios (p = 0.17). The genetic scenario scored a higher accuracy (p = 0.04) but lower sense of empowerment (p = 0.01). Furthermore, patients were more likely to seek additional testing after an ultrasound than after genetic testing (p = 0.05). There were no differences in other secondary outcomes including perception of life-altering consequences and hypothetical worry, anxiety, confusion, or medical care decisions. Our data suggest that uncertain findings on prenatal genetic testing do not elicit a higher perception of risk or anxiety when compared to ultrasound findings of comparable uncertainty. © 2015 John Wiley & Sons, Ltd. © 2015 John Wiley & Sons, Ltd.

Baseload coal investment decisions under uncertain carbon legislation.

PubMed

Bergerson, Joule A; Lave, Lester B

2007-05-15

More than 50% of electricity in the U.S. is generated by coal. The U.S. has large coal resources, the cheapest fuel in most areas. Coal fired power plants are likely to continue to provide much of U.S. electricity. However, the type of power plant that should be built is unclear. Technology can reduce pollutant discharges and capture and sequester the CO2 from coal-fired generation. The U.S. Energy Policy Act of 2005 provides incentives for large scale commercial deployment of Integrated Coal Gasification Combined Cycle (IGCC) systems (e.g., loan guarantees and project tax credits). This analysis examines whether a new coal plant should be Pulverized Coal (PC) or IGCC. Do stricter emissions standards (PM, SO2, NOx, Hg) justify the higher costs of IGCC over PC? How does potential future carbon legislation affect the decision to add carbon capture and storage (CCS) technology? Finally, can the impact of uncertain carbon legislation be minimized? We find that SO2, NOx, PM, and Hg emission standards would have to be far more stringent than twice current standards to justify the increased costs of the IGCC system. A C02 tax less than $29/ton would lead companies to continuing to choose PC, paying the tax for emitted CO2. The earlier a decision-maker believes the carbon tax will be imposed and the higher the tax, the more likely companies will choose IGCC w/CCS. Having government announce the date and level of a carbon tax would promote more sensible decisions, but government would have to use a tax or subsidy to induce companies to choose the technology that is best for society.

Resilience in social insect infrastructure systems

PubMed Central

2016-01-01

Both human and insect societies depend on complex and highly coordinated infrastructure systems, such as communication networks, supply chains and transportation networks. Like human-designed infrastructure systems, those of social insects are regularly subject to disruptions such as natural disasters, blockages or breaks in the transportation network, fluctuations in supply and/or demand, outbreaks of disease and loss of individuals. Unlike human-designed systems, there is no deliberate planning or centralized control system; rather, individual insects make simple decisions based on local information. How do these highly decentralized, leaderless systems deal with disruption? What factors make a social insect system resilient, and which factors lead to its collapse? In this review, we bring together literature on resilience in three key social insect infrastructure systems: transportation networks, supply chains and communication networks. We describe how systems differentially invest in three pathways to resilience: resistance, redirection or reconstruction. We suggest that investment in particular resistance pathways is related to the severity and frequency of disturbance. In the final section, we lay out a prospectus for future research. Human infrastructure networks are rapidly becoming decentralized and interconnected; indeed, more like social insect infrastructures. Human infrastructure management might therefore learn from social insect researchers, who can in turn make use of the mature analytical and simulation tools developed for the study of human infrastructure resilience. PMID:26962030

From Comb-like Polymers to Bottle-Brushes

NASA Astrophysics Data System (ADS)

Liang, Heyi; Cao, Zhen; Dobrynin, Andrey; Sheiko, Sergei

We use a combination of the coarse-grained molecular dynamics simulations and scaling analysis to study conformations of bottle-brushes and comb-like polymers in a melt. Our analysis show that bottle-brushes and comb-like polymers can be in four different conformation regimes depending on the number of monomers between grafted side chains and side chain degree of polymerization. In loosely-grafted comb regime (LC) the degree of polymerization between side chains is longer than side chain degree of polymerization, such that the side chains belonging to the same macromolecule do not overlap. Crossover to a new densely-grafted comb regime (DC) takes place when side chains begin to overlap reducing interpenetration of side chains belonging to different macromolecules. In these two regimes both side-chains and backbone behave as unperturbed linear chains with the effective Kuhn length of the backbone being close to that of linear chain. Further decrease spacer degree of polymerization results in crossover to loosely-grafted bottle-brush regime (LB). In this regime, the bottle-brush backbone is stretched while the side-chains still maintain ideal chain conformation. Finally, for even shorter spacer between grafted side chains, which corresponds to densely-grafted bottle-brush regime (DB), the backbone adopts a fully extended chain conformation, and side-chains begin to stretch to maintain a constant monomer density. NSF DMR-1409710, DMR-1407645, DMR-1624569, DMR-1436201.

Investigation of electronic transport through a ladder-like graphene nanoribbon including random distributed impurities

NASA Astrophysics Data System (ADS)

Esmaili, Esmat; Mardaani, Mohammad; Rabani, Hassan

2018-01-01

The electronic transport of a ladder-like graphene nanoribbon which the on-site or hopping energies of a small part of it can be random is modeled by using the Green's function technique within the nearest neighbor tight-binding approach. We employ a unitary transformation in order to convert the Hamiltonian of the nanoribbon to the Hamiltonian of a tight-binding ladder-like network. In this case, the disturbed part of the system includes the second neighbor hopping interactions. While, the converted Hamiltonian of each ideal part is equivalent to the Hamiltonian of two periodic on-site chains. Therefore, we can insert the self-energies of the alternative on-site tight-binding chains to the inverse of the Green's function matrix of the ladder-like part. In this viewpoint, the conductance is constructed from two trans and cis contributions. The results show that increasing the disorder strength causes the increase and decrease of the conductance of the trans and cis contributions, respectively.

A methodology for stochastic analysis of share prices as Markov chains with finite states.

PubMed

Mettle, Felix Okoe; Quaye, Enoch Nii Boi; Laryea, Ravenhill Adjetey

2014-01-01

Price volatilities make stock investments risky, leaving investors in critical position when uncertain decision is made. To improve investor evaluation confidence on exchange markets, while not using time series methodology, we specify equity price change as a stochastic process assumed to possess Markov dependency with respective state transition probabilities matrices following the identified state pace (i.e. decrease, stable or increase). We established that identified states communicate, and that the chains are aperiodic and ergodic thus possessing limiting distributions. We developed a methodology for determining expected mean return time for stock price increases and also establish criteria for improving investment decision based on highest transition probabilities, lowest mean return time and highest limiting distributions. We further developed an R algorithm for running the methodology introduced. The established methodology is applied to selected equities from Ghana Stock Exchange weekly trading data.

Fear and Trembling: Hong Kong Librarians Face Their Uncertain Future.

ERIC Educational Resources Information Center

Chepesiuk, Ron

1992-01-01

Discussion of the possible changes in Hong Kong in 1997 when rule passes to the People's Republic of China focuses on the uncertain future of libraries and librarians. Topics discussed include the political climate; the departure of qualified Chinese librarians; and the growth of libraries and computerized systems. (LRW)

Neural-network-based online HJB solution for optimal robust guaranteed cost control of continuous-time uncertain nonlinear systems.

PubMed

Liu, Derong; Wang, Ding; Wang, Fei-Yue; Li, Hongliang; Yang, Xiong

2014-12-01

In this paper, the infinite horizon optimal robust guaranteed cost control of continuous-time uncertain nonlinear systems is investigated using neural-network-based online solution of Hamilton-Jacobi-Bellman (HJB) equation. By establishing an appropriate bounded function and defining a modified cost function, the optimal robust guaranteed cost control problem is transformed into an optimal control problem. It can be observed that the optimal cost function of the nominal system is nothing but the optimal guaranteed cost of the original uncertain system. A critic neural network is constructed to facilitate the solution of the modified HJB equation corresponding to the nominal system. More importantly, an additional stabilizing term is introduced for helping to verify the stability, which reinforces the updating process of the weight vector and reduces the requirement of an initial stabilizing control. The uniform ultimate boundedness of the closed-loop system is analyzed by using the Lyapunov approach as well. Two simulation examples are provided to verify the effectiveness of the present control approach.

Robust stabilization of the Space Station in the presence of inertia matrix uncertainty

NASA Technical Reports Server (NTRS)

Wie, Bong; Liu, Qiang; Sunkel, John

1993-01-01

This paper presents a robust H-infinity full-state feedback control synthesis method for uncertain systems with D11 not equal to 0. The method is applied to the robust stabilization problem of the Space Station in the face of inertia matrix uncertainty. The control design objective is to find a robust controller that yields the largest stable hypercube in uncertain parameter space, while satisfying the nominal performance requirements. The significance of employing an uncertain plant model with D11 not equal 0 is demonstrated.

Li3Ge3Se6: the first ternary lithium germanium selenide with interesting ∞[Ge6Se12]n chains constructed by ethane-like [Ge2Se6]6- clusters.

PubMed

Li, Guangmao; Zhen, Ni; Chu, Yu; Zhou, Zhongxiang

2017-12-21

Li 3 Ge 3 Se 6 , the first compound of the ternary Li/Ge/Se system, has been synthesized. Note that interesting 1D ∞ [Ge 6 Se 12 ] n chains constructed by ethane-like [Ge 2 Se 6 ] 6- clusters were discovered in its structure. Investigations on the structures of all the [Ge 2 Se 6 ] 6- cluster-containing compounds have shown that only in Li 3 Ge 3 Se 6 are there 1D chains composed of [Ge 2 Se 6 ] 6- clusters, which result from the space limitation within the tunnels surrounded by LiSe 6 octahedra. Raman spectrum was obtained to demonstrate the existence of Ge-Ge bonds. UV-visible-NIR diffuse reflection spectrum showed an optical bandgap of 2.08 eV. Theoretical calculations based on first principles have also been performed for its band structure and density of states to analyze its structure-property relationship.

Influence of the nematic order on the rheology and conformation of stretched comb-like liquid crystalline polymers

NASA Astrophysics Data System (ADS)

Fourmaux-Demange, V.; Brûlet, A.; Boué, F.; Davidson, P.; Keller, P.; Cotton, J. P.

2000-04-01

We have studied the rheology and the conformation of stretched comb-like liquid-crystalline polymers. Both the influence of the comb-like structure and the specific effect of the nematic interaction on the dynamics are investigated. For this purpose, two isomers of a comb-like polymetacrylate polymer, of well-defined molecular weights, were synthesized: one displays a nematic phase over a wide range of temperature, the other one has only an isotropic phase. Even with high degrees of polymerization N, between 40 and 1000, the polymer chains studied were not entangled. The stress-strain curves during the stretching and relaxation processes show differences between the isotropic and nematic comb-like polymers. They suggest that, in the nematic phase, the chain dynamics is more cooperative than for a usual linear polymer. Small-angle neutron scattering has been used in order to determine the evolution of the chain conformation after stretching, as a function of the duration of relaxation t_r. The conformation can be described with two parameters only: λ_p, the global deformation of the polymer chain, and p, the number of statistical units of locally relaxed sub-chains. For the comb-like polymer, the chain deformation is pseudo-affine: λ_p is always smaller than λ (the deformation ratio of the whole sample). In the isotropic phase, λ_p has a constant value, while p increases as t_r. This latter behavior is not that expected for non-entangled chains, in which p varies as {t_r}^{1/2} (Rouse model). In the nematic phase, λ_p decreases as a stretched exponential function of t_r, while p remains constant. The dynamics of the comb-like polymers is discussed in terms of living clusters from which junctions are produced by interactions between side chains. The nematic interaction increases the lifetime of these junctions and, strikingly, the relaxation is the same at all scales of the whole polymer chain.

Hydrodynamic interactions of cilia on a spherical body

NASA Astrophysics Data System (ADS)

Nasouri, Babak; Elfring, Gwynn J.

2015-11-01

The emergence of metachronal waves in ciliated microorganisms can arise solely from the hydrodynamic interactions between the cilia. For a chain of cilia attached to a flat ciliate, it was observed that fluid forces can lead the system to form a metachronal wave. However, several microorganisms such as paramecium and volvox possess a curved shaped ciliate body. To understand the effect of this geometry on the formation of metachronal waves, we evaluate the hydrodynamic interactions of cilia near a large spherical body. Using a minimal model, we show that for a chain of cilia around the sphere, the embedded periodicity in the geometry leads the system to synchronize. We also report an emergent wave-like behavior when an asymmetry is introduced to the system.

Atwood's Heavy Chain

NASA Astrophysics Data System (ADS)

Beeken, Paul

2011-11-01

While perusing various websites in search of a more challenging lab for my students, I came across a number of ideas where replacing the string in an Atwood's machine with a simple ball chain like the kind found in lamp pulls created an interesting system to investigate. The replacement of the string produced a nice nonuniform acceleration, but one that my AP® students found difficult to analyze given their current math background. As the year progressed, we began to explore the importance of work and its utility in making predictions on systems that did not lend themselves to easy analysis using Newtonian mechanics. The effort made it apparent that the heavy rope Atwood's machine would make a perfect system for investigation using the lessons gained from work and energy.

A new smooth robust control design for uncertain nonlinear systems with non-vanishing disturbances

NASA Astrophysics Data System (ADS)

Xian, Bin; Zhang, Yao

2016-06-01

In this paper, we consider the control problem for a general class of nonlinear system subjected to uncertain dynamics and non-varnishing disturbances. A smooth nonlinear control algorithm is presented to tackle these uncertainties and disturbances. The proposed control design employs the integral of a nonlinear sigmoid function to compensate the uncertain dynamics, and achieve a uniformly semi-global practical asymptotic stable tracking control of the system outputs. A novel Lyapunov-based stability analysis is employed to prove the convergence of the tracking errors and the stability of the closed-loop system. Numerical simulation results on a two-link robot manipulator are presented to illustrate the performance of the proposed control algorithm comparing with the layer-boundary sliding mode controller and the robust of integration of sign of error control design. Furthermore, real-time experiment results for the attitude control of a quadrotor helicopter are also included to confirm the effectiveness of the proposed algorithm.

Event-triggered decentralized adaptive fault-tolerant control of uncertain interconnected nonlinear systems with actuator failures.

PubMed

Choi, Yun Ho; Yoo, Sung Jin

2018-06-01

This paper investigates the event-triggered decentralized adaptive tracking problem of a class of uncertain interconnected nonlinear systems with unexpected actuator failures. It is assumed that local control signals are transmitted to local actuators with time-varying faults whenever predefined conditions for triggering events are satisfied. Compared with the existing control-input-based event-triggering strategy for adaptive control of uncertain nonlinear systems, the aim of this paper is to propose a tracking-error-based event-triggering strategy in the decentralized adaptive fault-tolerant tracking framework. The proposed approach can relax drastic changes in control inputs caused by actuator faults in the existing triggering strategy. The stability of the proposed event-triggering control system is analyzed in the Lyapunov sense. Finally, simulation comparisons of the proposed and existing approaches are provided to show the effectiveness of the proposed theoretical result in the presence of actuator faults. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Comparative Physiological Studies of the Yeast and Mycelial Forms of Histoplasma capsulatum: Uptake and Incorporation of l-Leucine

PubMed Central

Gupta, Rishab K.; Howard, Dexter H.

1971-01-01

l-Leucine entered the cells of both morphological forms of Histoplasma capsulatum by a permease-like system at low external concentrations of substrate. However, at levels greater than 5 × 10−5m l-leucine, the amino acid entered the cells both through a simple diffusion-like process and the permease-like system. The rate of the amino acid diffusion into yeast and mycelial forms appeared to be the same, whereas the initial rate of accumulation through the permease-like system was 5 to 10 times faster in the mycelial phase than it was in the yeast phase. The Michaelis constants were 2.2 × 10−5m in yeast phase and 2 × 10−5m in mycelial phase cells. Transport of l-leucine at an external concentration of 10−5m showed all of the characteristics of a system of active transport, which was dependent on temperature and pH. Displacement or removal of the α-amino group, or modification of the α-carboxyl group abolished amino acid uptake. The process was competitively inhibited by neutral aliphatic side-chain amino acids (inhibition constants ranged from 1.5 × 10−5 to 6.2 × 10−5m). Neutral aromatic side-chain amino acids and the d-isomers of leucine and valine did not inhibit l-leucine uptake. These data were interpreted to mean that the l-leucine transport system is stereospecific and is highly specific for neutral aliphatic side-chain amino acids. Incorporation of l-leucine into macromolecules occurred at almost the same rate in both morphological forms of the fungus. The mycelial phase but not the yeast phase showed a slight initial lag in incorporation. In both morphological forms the intracellular pool of l-leucine was of limited capacity, and the total uptake of the amino acid was a function of intracellular pool size. The initial rate of l-leucine uptake was independent of the level of intracellular pool. Both morphological forms deaminated and degraded only a minor fraction of the accumulated leucine. PMID:4323295

Prediction-based control for LTI systems with uncertain time-varying delays and partial state knowledge

NASA Astrophysics Data System (ADS)

Léchappé, V.; Moulay, E.; Plestan, F.

2018-06-01

The stability of a prediction-based controller for linear time-invariant (LTI) systems is studied in the presence of time-varying input and output delays. The uncertain delay case is treated as well as the partial state knowledge case. The reduction method is used in order to prove the convergence of the closed-loop system including the state observer, the predictor and the plant. Explicit conditions that guarantee the closed-loop stability are given, thanks to a Lyapunov-Razumikhin analysis. Simulations illustrate the theoretical results.

The Impact of Model Uncertainty on Spatial Compensation in Structural Acoustic Control

NASA Technical Reports Server (NTRS)

Clark, Robert L.

2005-01-01

Turbulent boundary layer (TBL) noise is considered a primary contribution to the interior noise present in commercial airliners. There are numerous investigations of interior noise control devoted to aircraft panels; however, practical realization is a potential challenge since physical boundary conditions are uncertain at best. In most prior studies, pinned or clamped boundary conditions were assumed; however, realistic panels likely display a range of boundary conditions between these two limits. Uncertainty in boundary conditions is a challenge for control system designers, both in terms of the compensator implemented and the location of transducers required to achieve the desired control. The impact of model uncertainties, specifically uncertain boundaries, on the selection of transducer locations for structural acoustic control is considered herein. The final goal of this work is the design of an aircraft panel structure that can reduce TBL noise transmission through the use of a completely adaptive, single-input, single-output control system. The feasibility of this goal is demonstrated through the creation of a detailed analytical solution, followed by the implementation of a test model in a transmission loss apparatus. Successfully realizing a control system robust to variations in boundary conditions can lead to the design and implementation of practical adaptive structures that could be used to control the transmission of sound to the interior of aircraft. Results from this research effort indicate it is possible to optimize the design of actuator and sensor location and aperture, minimizing the impact of boundary conditions on the desired structural acoustic control.

Molecular dynamics study of intermediate phase of long chain alkyl sulfonate/water systems.

PubMed

Poghosyan, Armen H; Arsenyan, Levon H; Shahinyan, Aram A

2013-01-08

Using atomic level simulation we aimed to investigate various intermediate phases of the long chain alkyl sulfonate/water system. Overall, about 800 ns parallel molecular dynamics simulation study was conducted for a surfactant/water system consisting of 128 sodium pentadecyl sulfonate and 2251 water molecules. The GROMACS software code with united atom force field was applied. Despite some differences, the analysis of main structural parameters is in agreement with X-ray experimental findings. The mechanism of self-assembly of SPDS molecules was also examined. At T = 323 K we obtained both tilted fully interdigitated and liquid crystalline-like disordered hydrocarbon chains; hence, the presence of either gel phase that coexists with a lamellar phase or metastable gel phase with fraction of gauche configuration can be assumed. Further increase of temperature revealed that the system underwent a transition to a lamellar phase, which was clearly identified by the presence of fully disordered hydrocarbon chains. The transition from gel-to-fluid phase was implemented by simulated annealing treatment, and the phase transition point at T = 335 K was identified. The surfactant force field in its presented set is surely enabled to fully demonstrate the mechanism of self-assembly and the behavior of phase transition making it possible to get important information around the phase transition point.

A shark antibody heavy chain encoded by a nonsomatically rearranged VDJ is preferentially expressed in early development and is convergent with mammalian IgG

PubMed Central

Rumfelt, Lynn L.; Avila, David; Diaz, Marilyn; Bartl, Simona; McKinney, E. Churchill; Flajnik, Martin F.

2001-01-01

In most vertebrate embryos and neonates studied to date unique antigen receptors (antibodies and T cell receptors) are expressed that possess a limited immune repertoire. We have isolated a subclass of IgM, IgM1gj, from the nurse shark Ginglymostoma cirratum that is preferentially expressed in neonates. The variable (V) region gene encoding the heavy (H) chain underwent V-D-J rearrangement in germ cells (“germline-joined”). Such H chain V genes were discovered over 10 years ago in sharks but until now were not shown to be expressed at appreciable levels; we find expression of H1gj in primary and secondary lymphoid tissues early in life, but in adults only in primary lymphoid tissue, which is identified in this work as the epigonal organ. H1gj chain associates covalently with light (L) chains and is most similar in sequence to IgM H chains, but like mammalian IgG has three rather than the four IgM constant domains; deletion of the ancestral IgM C2 domain thus defines both IgG and IgM1gj. Because sharks are the members of the oldest vertebrate class known to possess antibodies, unique or specialized antibodies expressed early in ontogeny in sharks and other vertebrates were likely present at the inception of the adaptive immune system. PMID:11172027

Landscape heterogeneity shapes predation in a newly restored predator-prey system.

PubMed

Kauffman, Matthew J; Varley, Nathan; Smith, Douglas W; Stahler, Daniel R; MacNulty, Daniel R; Boyce, Mark S

2007-08-01

Because some native ungulates have lived without top predators for generations, it has been uncertain whether runaway predation would occur when predators are newly restored to these systems. We show that landscape features and vegetation, which influence predator detection and capture of prey, shape large-scale patterns of predation in a newly restored predator-prey system. We analysed the spatial distribution of wolf (Canis lupus) predation on elk (Cervus elaphus) on the Northern Range of Yellowstone National Park over 10 consecutive winters. The influence of wolf distribution on kill sites diminished over the course of this study, a result that was likely caused by territorial constraints on wolf distribution. In contrast, landscape factors strongly influenced kill sites, creating distinct hunting grounds and prey refugia. Elk in this newly restored predator-prey system should be able to mediate their risk of predation by movement and habitat selection across a heterogeneous risk landscape.

Landscape heterogeneity shapes predation in a newly restored predator-prey system

USGS Publications Warehouse

Kauffman, M.J.; Varley, N.; Smith, D.W.; Stahler, D.R.; MacNulty, D.R.; Boyce, M.S.

2007-01-01

Because some native ungulates have lived without top predators for generations, it has been uncertain whether runaway predation would occur when predators are newly restored to these systems. We show that landscape features and vegetation, which influence predator detection and capture of prey, shape large-scale patterns of predation in a newly restored predator-prey system. We analysed the spatial distribution of wolf (Canis lupus) predation on elk (Cervus elaphus) on the Northern Range of Yellowstone National Park over 10 consecutive winters. The influence of wolf distribution on kill sites diminished over the course of this study, a result that was likely caused by territorial constraints on wolf distribution. In contrast, landscape factors strongly influenced kill sites, creating distinct hunting grounds and prey refugia. Elk in this newly restored predator-prey system should be able to mediate their risk of predation by movement and habitat selection across a heterogeneous risk landscape. ?? 2007 Blackwell Publishing Ltd/CNRS.

Finite-time stabilization for a class of nonholonomic feedforward systems subject to inputs saturation.

PubMed

Gao, Fangzheng; Yuan, Ye; Wu, Yuqiang

2016-09-01

This paper studies the problem of finite-time stabilization by state feedback for a class of uncertain nonholonomic systems in feedforward-like form subject to inputs saturation. Under the weaker homogeneous condition on systems growth, a saturated finite-time control scheme is developed by exploiting the adding a power integrator method, the homogeneous domination approach and the nested saturation technique. Together with a novel switching control strategy, the designed saturated controller guarantees that the states of closed-loop system are regulated to zero in a finite time without violation of the constraint. As an application of the proposed theoretical results, the problem of saturated finite-time control for vertical wheel on rotating table is solved. Simulation results are given to demonstrate the effectiveness of the proposed method. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Decision blocks: A tool for automating decision making in CLIPS

NASA Technical Reports Server (NTRS)

Eick, Christoph F.; Mehta, Nikhil N.

1991-01-01

The human capability of making complex decision is one of the most fascinating facets of human intelligence, especially if vague, judgemental, default or uncertain knowledge is involved. Unfortunately, most existing rule based forward chaining languages are not very suitable to simulate this aspect of human intelligence, because of their lack of support for approximate reasoning techniques needed for this task, and due to the lack of specific constructs to facilitate the coding of frequently reoccurring decision block to provide better support for the design and implementation of rule based decision support systems. A language called BIRBAL, which is defined on the top of CLIPS, for the specification of decision blocks, is introduced. Empirical experiments involving the comparison of the length of CLIPS program with the corresponding BIRBAL program for three different applications are surveyed. The results of these experiments suggest that for decision making intensive applications, a CLIPS program tends to be about three times longer than the corresponding BIRBAL program.

Iterative Importance Sampling Algorithms for Parameter Estimation

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

Grout, Ray W; Morzfeld, Matthias; Day, Marcus S.

In parameter estimation problems one computes a posterior distribution over uncertain parameters defined jointly by a prior distribution, a model, and noisy data. Markov chain Monte Carlo (MCMC) is often used for the numerical solution of such problems. An alternative to MCMC is importance sampling, which can exhibit near perfect scaling with the number of cores on high performance computing systems because samples are drawn independently. However, finding a suitable proposal distribution is a challenging task. Several sampling algorithms have been proposed over the past years that take an iterative approach to constructing a proposal distribution. We investigate the applicabilitymore » of such algorithms by applying them to two realistic and challenging test problems, one in subsurface flow, and one in combustion modeling. More specifically, we implement importance sampling algorithms that iterate over the mean and covariance matrix of Gaussian or multivariate t-proposal distributions. Our implementation leverages massively parallel computers, and we present strategies to initialize the iterations using 'coarse' MCMC runs or Gaussian mixture models.« less

A Standardized DNA Variant Scoring System for Pathogenicity Assessments in Mendelian Disorders

PubMed Central

Karbassi, Izabela; Maston, Glenn A.; Love, Angela; DiVincenzo, Christina; Braastad, Corey D.; Elzinga, Christopher D.; Bright, Alison R.; Previte, Domenic; Zhang, Ke; Rowland, Charles M.; McCarthy, Michele; Lapierre, Jennifer L.; Dubois, Felicita; Medeiros, Katelyn A.; Batish, Sat Dev; Jones, Jeffrey; Liaquat, Khalida; Hoffman, Carol A.; Jaremko, Malgorzata; Wang, Zhenyuan; Sun, Weimin; Buller‐Burckle, Arlene; Strom, Charles M.; Keiles, Steven B.

2015-01-01

ABSTRACT We developed a rules‐based scoring system to classify DNA variants into five categories including pathogenic, likely pathogenic, variant of uncertain significance (VUS), likely benign, and benign. Over 16,500 pathogenicity assessments on 11,894 variants from 338 genes were analyzed for pathogenicity based on prediction tools, population frequency, co‐occurrence, segregation, and functional studies collected from internal and external sources. Scores were calculated by trained scientists using a quantitative framework that assigned differential weighting to these five types of data. We performed descriptive and comparative statistics on the dataset and tested interobserver concordance among the trained scientists. Private variants defined as variants found within single families (n = 5,182), were either VUS (80.5%; n = 4,169) or likely pathogenic (19.5%; n = 1,013). The remaining variants (n = 6,712) were VUS (38.4%; n = 2,577) or likely benign/benign (34.7%; n = 2,327) or likely pathogenic/pathogenic (26.9%, n = 1,808). Exact agreement between the trained scientists on the final variant score was 98.5% [95% confidence interval (CI) (98.0, 98.9)] with an interobserver consistency of 97% [95% CI (91.5, 99.4)]. Variant scores were stable and showed increasing odds of being in agreement with new data when re‐evaluated periodically. This carefully curated, standardized variant pathogenicity scoring system provides reliable pathogenicity scores for DNA variants encountered in a clinical laboratory setting. PMID:26467025

A Standardized DNA Variant Scoring System for Pathogenicity Assessments in Mendelian Disorders.

PubMed

Karbassi, Izabela; Maston, Glenn A; Love, Angela; DiVincenzo, Christina; Braastad, Corey D; Elzinga, Christopher D; Bright, Alison R; Previte, Domenic; Zhang, Ke; Rowland, Charles M; McCarthy, Michele; Lapierre, Jennifer L; Dubois, Felicita; Medeiros, Katelyn A; Batish, Sat Dev; Jones, Jeffrey; Liaquat, Khalida; Hoffman, Carol A; Jaremko, Malgorzata; Wang, Zhenyuan; Sun, Weimin; Buller-Burckle, Arlene; Strom, Charles M; Keiles, Steven B; Higgins, Joseph J

2016-01-01

We developed a rules-based scoring system to classify DNA variants into five categories including pathogenic, likely pathogenic, variant of uncertain significance (VUS), likely benign, and benign. Over 16,500 pathogenicity assessments on 11,894 variants from 338 genes were analyzed for pathogenicity based on prediction tools, population frequency, co-occurrence, segregation, and functional studies collected from internal and external sources. Scores were calculated by trained scientists using a quantitative framework that assigned differential weighting to these five types of data. We performed descriptive and comparative statistics on the dataset and tested interobserver concordance among the trained scientists. Private variants defined as variants found within single families (n = 5,182), were either VUS (80.5%; n = 4,169) or likely pathogenic (19.5%; n = 1,013). The remaining variants (n = 6,712) were VUS (38.4%; n = 2,577) or likely benign/benign (34.7%; n = 2,327) or likely pathogenic/pathogenic (26.9%, n = 1,808). Exact agreement between the trained scientists on the final variant score was 98.5% [95% confidence interval (CI) (98.0, 98.9)] with an interobserver consistency of 97% [95% CI (91.5, 99.4)]. Variant scores were stable and showed increasing odds of being in agreement with new data when re-evaluated periodically. This carefully curated, standardized variant pathogenicity scoring system provides reliable pathogenicity scores for DNA variants encountered in a clinical laboratory setting. © 2015 The Authors. **Human Mutation published by Wiley Periodicals, Inc.

Algorithms for sum-of-squares-based stability analysis and control design of uncertain nonlinear systems

NASA Astrophysics Data System (ADS)

Ataei-Esfahani, Armin

In this dissertation, we present algorithmic procedures for sum-of-squares based stability analysis and control design for uncertain nonlinear systems. In particular, we consider the case of robust aircraft control design for a hypersonic aircraft model subject to parametric uncertainties in its aerodynamic coefficients. In recent years, Sum-of-Squares (SOS) method has attracted increasing interest as a new approach for stability analysis and controller design of nonlinear dynamic systems. Through the application of SOS method, one can describe a stability analysis or control design problem as a convex optimization problem, which can efficiently be solved using Semidefinite Programming (SDP) solvers. For nominal systems, the SOS method can provide a reliable and fast approach for stability analysis and control design for low-order systems defined over the space of relatively low-degree polynomials. However, The SOS method is not well-suited for control problems relating to uncertain systems, specially those with relatively high number of uncertainties or those with non-affine uncertainty structure. In order to avoid issues relating to the increased complexity of the SOS problems for uncertain system, we present an algorithm that can be used to transform an SOS problem with uncertainties into a LMI problem with uncertainties. A new Probabilistic Ellipsoid Algorithm (PEA) is given to solve the robust LMI problem, which can guarantee the feasibility of a given solution candidate with an a-priori fixed probability of violation and with a fixed confidence level. We also introduce two approaches to approximate the robust region of attraction (RROA) for uncertain nonlinear systems with non-affine dependence on uncertainties. The first approach is based on a combination of PEA and SOS method and searches for a common Lyapunov function, while the second approach is based on the generalized Polynomial Chaos (gPC) expansion theorem combined with the SOS method and searches for parameter-dependent Lyapunov functions. The control design problem is investigated through a case study of a hypersonic aircraft model with parametric uncertainties. Through time-scale decomposition and a series of function approximations, the complexity of the aircraft model is reduced to fall within the capability of SDP solvers. The control design problem is then formulated as a convex problem using the dual of the Lyapunov theorem. A nonlinear robust controller is searched using the combined PEA/SOS method. The response of the uncertain aircraft model is evaluated for two sets of pilot commands. As the simulation results show, the aircraft remains stable under up to 50% uncertainty in aerodynamic coefficients and can follow the pilot commands.

Novel density-based and hierarchical density-based clustering algorithms for uncertain data.

PubMed

Zhang, Xianchao; Liu, Han; Zhang, Xiaotong

2017-09-01

Uncertain data has posed a great challenge to traditional clustering algorithms. Recently, several algorithms have been proposed for clustering uncertain data, and among them density-based techniques seem promising for handling data uncertainty. However, some issues like losing uncertain information, high time complexity and nonadaptive threshold have not been addressed well in the previous density-based algorithm FDBSCAN and hierarchical density-based algorithm FOPTICS. In this paper, we firstly propose a novel density-based algorithm PDBSCAN, which improves the previous FDBSCAN from the following aspects: (1) it employs a more accurate method to compute the probability that the distance between two uncertain objects is less than or equal to a boundary value, instead of the sampling-based method in FDBSCAN; (2) it introduces new definitions of probability neighborhood, support degree, core object probability, direct reachability probability, thus reducing the complexity and solving the issue of nonadaptive threshold (for core object judgement) in FDBSCAN. Then, we modify the algorithm PDBSCAN to an improved version (PDBSCANi), by using a better cluster assignment strategy to ensure that every object will be assigned to the most appropriate cluster, thus solving the issue of nonadaptive threshold (for direct density reachability judgement) in FDBSCAN. Furthermore, as PDBSCAN and PDBSCANi have difficulties for clustering uncertain data with non-uniform cluster density, we propose a novel hierarchical density-based algorithm POPTICS by extending the definitions of PDBSCAN, adding new definitions of fuzzy core distance and fuzzy reachability distance, and employing a new clustering framework. POPTICS can reveal the cluster structures of the datasets with different local densities in different regions better than PDBSCAN and PDBSCANi, and it addresses the issues in FOPTICS. Experimental results demonstrate the superiority of our proposed algorithms over the existing algorithms in accuracy and efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

Experiences with Probabilistic Analysis Applied to Controlled Systems

NASA Technical Reports Server (NTRS)

Kenny, Sean P.; Giesy, Daniel P.

2004-01-01

This paper presents a semi-analytic method for computing frequency dependent means, variances, and failure probabilities for arbitrarily large-order closed-loop dynamical systems possessing a single uncertain parameter or with multiple highly correlated uncertain parameters. The approach will be shown to not suffer from the same computational challenges associated with computing failure probabilities using conventional FORM/SORM techniques. The approach is demonstrated by computing the probabilistic frequency domain performance of an optimal feed-forward disturbance rejection scheme.

The roles of productivity and ecosystem size in determining food chain length in tropical terrestrial ecosystems.

PubMed

Young, Hillary S; McCauley, Douglas J; Dunbar, Robert B; Hutson, Michael S; Ter-Kuile, Ana Miller; Dirzo, Rodolfo

2013-03-01

Many different drivers, including productivity, ecosystem size, and disturbance, have been considered to explain natural variation in the length of food chains. Much remains unknown about the role of these various drivers in determining food chain length, and particularly about the mechanisms by which they may operate in terrestrial ecosystems, which have quite different ecological constraints than aquatic environments, where most food chain length studies have been thus far conducted. In this study, we tested the relative importance of ecosystem size and productivity in influencing food chain length in a terrestrial setting. We determined that (1) there is no effect of ecosystem size or productive space on food chain length; (2) rather, food chain length increases strongly and linearly with productivity; and (3) the observed changes in food chain length are likely achieved through a combination of changes in predator size, predator behavior, and consumer diversity along gradients in productivity. These results lend new insight into the mechanisms by which productivity can drive changes in food chain length, point to potential for systematic differences in the drivers of food web structure between terrestrial and aquatic systems, and challenge us to consider how ecological context may control the drivers that shape food chain length.

Babesia (Theileria) annae in a red fox (Vulpes vulpes) from Prince Edward Island, Canada.

PubMed

Clancey, Noel; Horney, Barbara; Burton, Shelley; Birkenheuer, Adam; McBurney, Scott; Tefft, Karen

2010-04-01

A 4-6-mo-old female red fox (Vulpes vulpes) was presented to the Atlantic Veterinary College (AVC) Teaching Hospital, Prince Edward Island, Canada. On presentation, the fox was weak and had pale mucous membranes. A complete blood count and a serum biochemistry profile were performed. Blood smear examination revealed low numbers of erythrocytes containing centrally to paracentrally located, single, rarely multiple, approximately 1 x 2 microm, oval to round organisms with morphology similar to Babesia microti. Polymerase chain reaction testing and DNA sequencing of the Babesia species 18S rRNA gene were performed on DNA extracted from whole blood. Results were positive for a Babesia microti-like parasite genetically identical to Babesia (Theileria) annae. The fox was euthanized due to poor prognosis for recovery. Necropsy examination revealed multifocal to locally extensive subacute nonsuppurative meningoencephalitis, an eosinophilic broncho-pneumonia, a moderate diffuse vacuolar hepatopathy, and lesions associated with blunt trauma to the left abdominal region. This is the first reported case of a red fox in Canada infected with a piroplasm. It remains uncertain whether the presence of this hemoparasite in this fox was pathogenic or an incidental finding. The potential for competent vectors of Babesia species on Prince Edward Island, the potential for this Babesia microti-like parasite to infect other wild and domestic canids, and the significance of this parasite to the health of infected individuals are yet to be determined.

pH responsiveness of dendrimer-like poly(ethylene oxide)s.

PubMed

Feng, Xiaoshuang; Taton, Daniel; Borsali, Redouane; Chaikof, Elliot L; Gnanou, Yves

2006-09-06

Poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA), two polymers known to form pH-sensitive aggregates through noncovalent interactions, were assembled in purposely designed architecture -a dendrimer-like PEO scaffold carrying short inner PAA chains-to produce unimolecular systems that exhibit pH responsiveness. Because of the particular placement of the PAA chains within the dendrimer-like structure, intermolecular complexation between acrylic acid (AA) and ethylene oxide (EO) units-and thus macroscopic aggregation or even mesoscopic micellization-could be avoided in favor of the sole intramolecular complexation. The sensitivity of such interactions to pH was exploited to generate dendrimer-like PEOs that reversibly shrink and expand with the pH. Such PAA-carrying dendrimer-like PEOs were synthesized in two main steps. First, a fifth-generation dendrimer-like PEO was obtained by combining anionic ring-opening polymerization (AROP) of ethylene oxide from a tris-hydroxylated core and selective branching reactions of PEO chain ends. To this end, an AB(2)C-type branching agent was designed: the latter includes a chloromethyl (A) group for its covalent attachment to the arm ends, two geminal hydroxyls (B(2)) protected in the form of a ketal ring for the growth of subsequent PEO generations by AROP, and a vinylic (C) double bonds for further functionalization of the interior of dendrimer-like PEOs. Reiteration of AROP and derivatization of PEO branches allowed us to prepare a dendrimer-like PEO of fourth generation with a total molar mass of 52,000 g x mol(-1), containing 24 external hydroxyl functions and 21 inner vinylic groups in the interior. A fifth generation of PEO chains was generated from this parent dendrimer-like PEO of fourth generation using a "conventional" AB(2)-type branching agent, and 48 PEO branches could be grown by AROP. The 48 outer hydroxy-end groups of the fifth-generation dendrimer-like PEO obtained were subsequently quantitatively converted into inert benzylic groups using benzyl bromide. The 21 internal vinylic groups carried by the PEO scaffold were then chemically modified in a two-step sequence into bromoester groups. The latter which are atom transfer radical polymerization (ATRP) initiating sites thus served to grow poly(tert-butylacrylate) chains. After a final step of hydrolysis of the tert-butyl ester groups, double, hydrophilic, dendrimer-like PEOs comprising 21 internal junction-attached poly(acrylic acid) (PAA) blocks could be obtained. Dynamic light scattering was used to determine the size of these dendrimer-like species in water and to investigate their response to pH variation: in particular, how the pH-sensitive complexation of EO and AA units affects their overall behavior.

Simulation Studies of LCST-like Phase Transitions in Elastin-like Polypeptides (ELPs) and Conjugates of ELP with Rigid Macromolecules

NASA Astrophysics Data System (ADS)

Condon, Joshua; Martin, Tyler; Jayaraman, Arthi

We use atomistic (AA) and coarse-grained (CG) molecular dynamics simulations to elucidate the thermodynamic driving forces governing lower critical solution temperature (LCST)-like phase transition exhibited by elastin-like peptides (ELPs) and conjugates of ELP with other macromolecules. In the AA simulations, we study ELP oligomers in explicit water, and mark the transition as the temperature at which they undergo a change in ``hydration'' state. While AA simulations are restricted to small systems of short ELPs and do not capture the chain aggregation observed in experiments of ELPs, they guide the phenomenological CG model development by highlighting the solvent induced polymer-polymer effective interactions with changing temperature. In the CG simulations, we capture the LCST polymer aggregation by increasing polymer-polymer effective attractive interactions in an implicit solvent. We examine the impact of conjugating a block of LCST polymer to another rigid unresponsive macromolecular block on the LCST-like transition. We find that when multiple LCST polymers are conjugated to a rigid polymer block, increased crowding of the LCST polymers shifts the onset of chain aggregation to smaller effective polymer-polymer attraction compared to the free LCST polymers. These simulation results provide guidance on the design of conjugated bio-mimetic thermoresponsive materials, and shape the fundamental understanding of the impact of polymer crowding on phase behavior in thermoresponsive LCST polymer systems.

Resolution of an uncertain closed-loop logistics model: an application to fuzzy linear programs with risk analysis.

PubMed

Wang, Hsiao-Fan; Hsu, Hsin-Wei

2010-11-01

With the urgency of global warming, green supply chain management, logistics in particular, has drawn the attention of researchers. Although there are closed-loop green logistics models in the literature, most of them do not consider the uncertain environment in general terms. In this study, a generalized model is proposed where the uncertainty is expressed by fuzzy numbers. An interval programming model is proposed by the defined means and mean square imprecision index obtained from the integrated information of all the level cuts of fuzzy numbers. The resolution for interval programming is based on the decision maker (DM)'s preference. The resulting solution provides useful information on the expected solutions under a confidence level containing a degree of risk. The results suggest that the more optimistic the DM is, the better is the resulting solution. However, a higher risk of violation of the resource constraints is also present. By defining this probable risk, a solution procedure was developed with numerical illustrations. This provides a DM trade-off mechanism between logistic cost and the risk. Copyright 2010 Elsevier Ltd. All rights reserved.

Alignment between chain quality management and chain governance in EU pork supply chains: a Transaction-Cost-Economics perspective.

PubMed

Wever, Mark; Wognum, Nel; Trienekens, Jacques; Omta, Onno

2010-02-01

Although inter-firm coordination of quality management is increasingly important for meeting end-customer demand in agri-food chains, few researchers focus on the relation between inter-firm quality management systems (QMS) and inter-firm governance structures (GS). However, failure to align QMSs and GSs may lead to inefficiencies in quality management because of high transaction-costs. In addition, misalignment is likely to reduce the quality of end-customer products. This paper addresses this gap in research by empirically examining the relation between QMSs and GSs in pork meat supply chains. Transaction-Cost-Economic theory is used to develop propositions about the relation between three aspects of QMSs--ownership, vertical scope and scale of adoption--and the use of different types of GSs in pork meat supply chains. To validate the propositions, seven cases are examined from four different countries. The results show that the different aspects of QMSs largely relate to specific GSs used in chains in the manner predicted by the propositions. This supports the view that alignment between QMSs and GSs is important for the efficient coordination of quality management in (pork meat) supply chains.

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

Hansen, Jason K.; Jacobson, Jacob J.; Cafferty, Kara G.

In order to increase the sustainability and security of the nation’s energy supply, the U.S. Department of Energy through its Bioenergy Technology Office has set a vision for one billion tons of biomass to be processed for renewable energy and bioproducts annually by the year 2030. The Renewable Fuels Standard limits the amount of corn grain that can be used in ethanol conversion sold in the U.S, which is already at its maximum. Therefore making the DOE’s vision a reality requires significant growth in the advanced biofuels industry where currently three cellulosic biorefineries convert cellulosic biomass to ethanol. Risk mitigationmore » is central to growing the industry beyond its infancy to a level necessary to achieve the DOE vision. This paper focuses on reducing the supply risk that faces a firm that owns a cellulosic biorefinery. It uses risk theory and simulation modeling to build a risk assessment model based on causal relationships of underlying, uncertain, supply driving variables. Using the model the paper quantifies supply risk reduction achieved by converting the supply chain from a conventional supply system (bales and trucks) to an advanced supply system (depots, pellets, and trains). Results imply that the advanced supply system reduces supply system risk, defined as the probability of a unit cost overrun, from 83% in the conventional system to 4% in the advanced system. Reducing cost risk in this nascent industry improves the odds of realizing desired growth.« less

Testing the equivalence principle on cosmological scales

NASA Astrophysics Data System (ADS)

Bonvin, Camille; Fleury, Pierre

2018-05-01

The equivalence principle, that is one of the main pillars of general relativity, is very well tested in the Solar system; however, its validity is more uncertain on cosmological scales, or when dark matter is concerned. This article shows that relativistic effects in the large-scale structure can be used to directly test whether dark matter satisfies Euler's equation, i.e. whether its free fall is characterised by geodesic motion, just like baryons and light. After having proposed a general parametrisation for deviations from Euler's equation, we perform Fisher-matrix forecasts for future surveys like DESI and the SKA, and show that such deviations can be constrained with a precision of order 10%. Deviations from Euler's equation cannot be tested directly with standard methods like redshift-space distortions and gravitational lensing, since these observables are not sensitive to the time component of the metric. Our analysis shows therefore that relativistic effects bring new and complementary constraints to alternative theories of gravity.

Menu labeling regulations and calories purchased at chain restaurants.

PubMed

Krieger, James W; Chan, Nadine L; Saelens, Brian E; Ta, Myduc L; Solet, David; Fleming, David W

2013-06-01

The federal menu labeling law will require chain restaurants to post caloric information on menus, but the impact of labeling is uncertain. The goal of the current study was to examine the effect of menu labeling on calories purchased, and secondarily, to assess self-reported awareness and use of labels. Single-community pre-post-post cross-sectional study. Data were collected in 2008-2010 and analyzed in 2011-2012. 50 sites from 10 chain restaurants in King County, Washington, selected through stratified, two-stage cluster random sampling. A total of 7325 customers participated. Eligibility criteria were: being an English speaker, aged ≥ 14 years, and having an itemized receipt. The study population was 59% male, 76% white non-Hispanic, and 53% aged<40 years. A regulation requiring chain restaurants to post calorie information on menus or menu boards was implemented. Mean number of calories purchased. No significant changes occurred between baseline and 4-6 months postregulation. Mean calories per purchase decreased from 908.5 to 870.4 at 18 months post-implementation (38 kcal, 95% CI=-76.9, 0.8, p=0.06) in food chains and from 154.3 to 132.1 (22 kcal, 95% CI=-35.8, -8.5, p=0.002) in coffee chains. Calories decreased in taco and coffee chains, but not in burger and sandwich establishments. They decreased more among women than men in coffee chains. Awareness of labels increased from 18.8% to 61.7% in food chains and from 4.4% to 30.0% in coffee chains (both p<0.001). Among customers seeing calorie information, the proportion using it (about one third) did not change substantially over time. After implementation, food chain customers using information purchased on average fewer calories compared to those seeing but not using (difference=143.2 kcal, p<0.001) and those not seeing (difference=135.5 kcal, p<0.001) such information. Mean calories per purchase decreased 18 months after implementation of menu labeling in some restaurant chains and among women but not men. Copyright © 2013. Published by Elsevier Inc.

Distributed Episodic and Analogical Reasoning (DEAR)

DTIC Science & Technology

2010-04-01

of a more abstract class like environmental catastrophe. Analogical reasoning researchers like Gentner and Stevens (1983) caution that “the...hurricane and an earthquake can be useful for quickly determining how to respond to an environmental catastrophe in general but will need to be...with Uncertain Dynamic Outside Options. Proceedings of the First IEEE International Workshop on Electronic Contracting ( WEC 󈧈), p.54-61, July 06-06

Molecular theory of lipid-protein interaction and the Lalpha-HII transition.

PubMed Central

May, S; Ben-Shaul, A

1999-01-01

We present a molecular-level theory for lipid-protein interaction and apply it to the study of lipid-mediated interactions between proteins and the protein-induced transition from the planar bilayer (Lalpha) to the inverse-hexagonal (HII) phase. The proteins are treated as rigid, membrane-spanning, hydrophobic inclusions of different size and shape, e.g., "cylinder-like," "barrel-like," or "vase-like." We assume strong hydrophobic coupling between the protein and its neighbor lipids. This means that, if necessary, the flexible lipid chains surrounding the protein will stretch, compress, and/or tilt to bridge the hydrophobic thickness mismatch between the protein and the unperturbed bilayer. The system free energy is expressed as an integral over local molecular contributions, the latter accounting for interheadgroup repulsion, hydrocarbon-water surface energy, and chain stretching-tilting effects. We show that the molecular interaction constants are intimately related to familiar elastic (continuum) characteristics of the membrane, such as the bending rigidity and spontaneous curvature, as well as to the less familiar tilt modulus. The equilibrium configuration of the membrane is determined by minimizing the free energy functional, subject to boundary conditions dictated by the size, shape, and spatial distribution of inclusions. A similar procedure is used to calculate the free energy and structure of peptide-free and peptide-rich hexagonal phases. Two degrees of freedom are involved in the variational minimization procedure: the local length and local tilt angle of the lipid chains. The inclusion of chain tilt is particularly important for studying noncylindrical (for instance, barrel-like) inclusions and analyzing the structure of the HII lipid phase; e.g., we find that chain tilt relaxation implies strong faceting of the lipid monolayers in the hexagonal phase. Consistent with experiment, we find that only short peptides (large negative mismatch) can induce the Lalpha --> HII transition. At the transition, a peptide-poor Lalpha phase coexists with a peptide-rich HII phase. PMID:9929479

Focused Logistics: Putting Agility in Agile Logistics

DTIC Science & Technology

2011-05-19

list, ahead of companies like American Express, DuPont and Coca Cola ; Supports nearly 1,900 weapon systems; DLA manages eight supply chains and...35 7) Force Health Protection...Distribution, Information Fusion, Joint Theater Logistics Command and Control, Multinational Logistics, Joint Health Services Support, and Agile

"The impact of uncertain threat on affective bias: Individual differences in response to ambiguity": Correction.

PubMed

2018-04-01

Reports an error in "The impact of uncertain threat on affective bias: Individual differences in response to ambiguity" by Maital Neta, Julie Cantelon, Zachary Haga, Caroline R. Mahoney, Holly A. Taylor and F. Caroline Davis ( Emotion , 2017[Dec], Vol 17[8], 1137-1143). In this article, the copyright attribution was incorrectly listed under the Creative Commons CC-BY license due to production-related error. The correct copyright should be "In the public domain." The online version of this article has been corrected. (The following abstract of the original article appeared in record 2017-40275-001.) Individuals who operate under highly stressful conditions (e.g., military personnel and first responders) are often faced with the challenge of quickly interpreting ambiguous information in uncertain and threatening environments. When faced with ambiguity, it is likely adaptive to view potentially dangerous stimuli as threatening until contextual information proves otherwise. One laboratory-based paradigm that can be used to simulate uncertain threat is known as threat of shock (TOS), in which participants are told that they might receive mild but unpredictable electric shocks while performing an unrelated task. The uncertainty associated with this potential threat induces a state of emotional arousal that is not overwhelmingly stressful, but has widespread-both adaptive and maladaptive-effects on cognitive and affective function. For example, TOS is thought to enhance aversive processing and abolish positivity bias. Importantly, in certain situations (e.g., when walking home alone at night), this anxiety can promote an adaptive state of heightened vigilance and defense mobilization. In the present study, we used TOS to examine the effects of uncertain threat on valence bias, or the tendency to interpret ambiguous social cues as positive or negative. As predicted, we found that heightened emotional arousal elicited by TOS was associated with an increased tendency to interpret ambiguous cues negatively. Such negative interpretations are likely adaptive in situations in which threat detection is critical for survival and should override an individual's tendency to interpret ambiguity positively in safe contexts. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Oxidative stress in entomopathogenic fungi grown on insect-like hydrocarbons.

PubMed

Huarte-Bonnet, Carla; Juárez, M Patricia; Pedrini, Nicolás

2015-08-01

Entomopathogenic fungi mostly attack their insect hosts by penetration through the cuticle. The outermost insect surface is covered by a lipid-rich layer, usually composed of very long chain hydrocarbons. These fungi are apt to grow on straight chain hydrocarbons (alkanes) as the sole carbon source. Insect-like hydrocarbons are first hydroxylated by a microsomal P450 monooxygenase system, and then fully catabolized by peroxisomal β-oxidation reactions in Beauveria bassiana. In this review, we will discuss lipid metabolism adaptations in alkane-grown fungi, and how an oxidative stress scenario is established under these conditions. Fungi have to pay a high cost for hydrocarbon utilization; high levels of reactive oxygen species are produced and a concomitant antioxidant response is triggered in fungal cells to cope with this drawback.

Transportation and dynamic networks: Models, theory, and applications to supply chains, electric power, and financial networks

NASA Astrophysics Data System (ADS)

Liu, Zugang

Network systems, including transportation and logistic systems, electric power generation and distribution networks as well as financial networks, provide the critical infrastructure for the functioning of our societies and economies. The understanding of the dynamic behavior of such systems is also crucial to national security and prosperity. The identification of new connections between distinct network systems is the inspiration for the research in this dissertation. In particular, I answer two questions raised by Beckmann, McGuire, and Winsten (1956) and Copeland (1952) over half a century ago, which are, respectively, how are electric power flows related to transportation flows and does money flow like water or electricity? In addition, in this dissertation, I achieve the following: (1) I establish the relationships between transportation networks and three other classes of complex network systems: supply chain networks, electric power generation and transmission networks, and financial networks with intermediation. The establishment of such connections provides novel theoretical insights as well as new pricing mechanisms, and efficient computational methods. (2) I develop new modeling frameworks based on evolutionary variational inequality theory that capture the dynamics of such network systems in terms of the time-varying flows and incurred costs, prices, and, where applicable, profits. This dissertation studies the dynamics of such network systems by addressing both internal competition and/or cooperation, and external changes, such as varying costs and demands. (3) I focus, in depth, on electric power supply chains. By exploiting the relationships between transportation networks and electric power supply chains, I develop a large-scale network model that integrates electric power supply chains and fuel supply markets. The model captures both the economic transactions as well as the physical transmission constraints. The model is then applied to the New England electric power supply chain consisting of 6 states, 5 fuel types, 82 power generators, with a total of 573 generating units, and 10 demand markets. The empirical case study demonstrates that the regional electricity prices simulated by the model match very well the actual electricity prices in New England. I also utilize the model to study interactions between electric power supply chains and energy fuel markets.

Wind turbine model and loop shaping controller design

NASA Astrophysics Data System (ADS)

Gilev, Bogdan

2017-12-01

A model of a wind turbine is evaluated, consisting of: wind speed model, mechanical and electrical model of generator and tower oscillation model. Model of the whole system is linearized around of a nominal point. By using the linear model with uncertainties is synthesized a uncertain model. By using the uncertain model is developed a H∞ controller, which provide mode of stabilizing the rotor frequency and damping the tower oscillations. Finally is simulated work of nonlinear system and H∞ controller.

Design Flexibility for Uncertain Distributed Generation from Photovoltaics

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

Palmintier, Bryan; Krishnamurthy, Dheepak; Wu, Hongyu

2016-12-12

Uncertainty in the future adoption patterns for distributed energy resources (DERs) introduces a challenge for electric distribution system planning. This paper explores the potential for flexibility in design - also known as real options - to identify design solutions that may never emerge when future DER patterns are treated as deterministic. A test case for storage system design with uncertain distributed generation for solar photovoltaics (DGPV) demonstrates this approach and is used to study sensitivities to a range of techno-economic assumptions.

Resilience in social insect infrastructure systems.

PubMed

Middleton, Eliza J T; Latty, Tanya

2016-03-01

Both human and insect societies depend on complex and highly coordinated infrastructure systems, such as communication networks, supply chains and transportation networks. Like human-designed infrastructure systems, those of social insects are regularly subject to disruptions such as natural disasters, blockages or breaks in the transportation network, fluctuations in supply and/or demand, outbreaks of disease and loss of individuals. Unlike human-designed systems, there is no deliberate planning or centralized control system; rather, individual insects make simple decisions based on local information. How do these highly decentralized, leaderless systems deal with disruption? What factors make a social insect system resilient, and which factors lead to its collapse? In this review, we bring together literature on resilience in three key social insect infrastructure systems: transportation networks, supply chains and communication networks. We describe how systems differentially invest in three pathways to resilience: resistance, redirection or reconstruction. We suggest that investment in particular resistance pathways is related to the severity and frequency of disturbance. In the final section, we lay out a prospectus for future research. Human infrastructure networks are rapidly becoming decentralized and interconnected; indeed, more like social insect infrastructures. Human infrastructure management might therefore learn from social insect researchers, who can in turn make use of the mature analytical and simulation tools developed for the study of human infrastructure resilience. © 2016 The Author(s).

Chains are more flexible under tension

PubMed Central

Carrillo, Jan-Michael Y.; Rubinstein, Michael

2010-01-01

The mechanical response of networks, gels, and brush layers is a manifestation of the elastic properties of the individual macromolecules. Furthermore, the elastic response of macromolecules to an applied force is the foundation of the single-molecule force spectroscopy techniques. The two main classes of models describing chain elasticity include the worm-like and freely-jointed chain models. The selection between these two classes of models is based on the assumptions about chain flexibility. In many experimental situations the choice is not clear and a model describing the crossover between these two limiting classes is therefore in high demand. We are proposing a unified chain deformation model which describes the force-deformation curve in terms of the chain bending constant K and bond length b. This model demonstrates that the worm-like and freely-jointed chain models correspond to two different regimes of polymer deformation and the crossover between these two regimes depends on the chain bending rigidity and the magnitude of the applied force. Polymer chains with bending constant K>1 behave as a worm-like chain under tension in the interval of the applied forces f ≤ KkBT/b and as a freely-jointed chain for f ≥ KkBT/b (kB is the Boltzmann constant and T is the absolute temperature). The proposed crossover expression for chain deformation is in excellent agreement with the results of the molecular dynamics simulations of chain deformation and single-molecule deformation experiments of biological and synthetic macromolecules. PMID:21415940

Information Theoretically Secure, Enhanced Johnson Noise Based Key Distribution over the Smart Grid with Switched Filters

PubMed Central

2013-01-01

We introduce a protocol with a reconfigurable filter system to create non-overlapping single loops in the smart power grid for the realization of the Kirchhoff-Law-Johnson-(like)-Noise secure key distribution system. The protocol is valid for one-dimensional radial networks (chain-like power line) which are typical of the electricity distribution network between the utility and the customer. The speed of the protocol (the number of steps needed) versus grid size is analyzed. When properly generalized, such a system has the potential to achieve unconditionally secure key distribution over the smart power grid of arbitrary geometrical dimensions. PMID:23936164

Information theoretically secure, enhanced Johnson noise based key distribution over the smart grid with switched filters.

PubMed

Gonzalez, Elias; Kish, Laszlo B; Balog, Robert S; Enjeti, Prasad

2013-01-01

We introduce a protocol with a reconfigurable filter system to create non-overlapping single loops in the smart power grid for the realization of the Kirchhoff-Law-Johnson-(like)-Noise secure key distribution system. The protocol is valid for one-dimensional radial networks (chain-like power line) which are typical of the electricity distribution network between the utility and the customer. The speed of the protocol (the number of steps needed) versus grid size is analyzed. When properly generalized, such a system has the potential to achieve unconditionally secure key distribution over the smart power grid of arbitrary geometrical dimensions.

Stronger steerability criterion for more uncertain continuous-variable systems

NASA Astrophysics Data System (ADS)

Chowdhury, Priyanka; Pramanik, Tanumoy; Majumdar, A. S.

2015-10-01

We derive a fine-grained uncertainty relation for the measurement of two incompatible observables on a single quantum system of continuous variables, and show that continuous-variable systems are more uncertain than discrete-variable systems. Using the derived fine-grained uncertainty relation, we formulate a stronger steering criterion that is able to reveal the steerability of NOON states that has hitherto not been possible using other criteria. We further obtain a monogamy relation for our steering inequality which leads to an, in principle, improved lower bound on the secret key rate of a one-sided device independent quantum key distribution protocol for continuous variables.

Robust adaptive sliding mode control for uncertain systems with unknown time-varying delay input.

PubMed

Benamor, Anouar; Messaoud, Hassani

2018-05-02

This article focuses on robust adaptive sliding mode control law for uncertain discrete systems with unknown time-varying delay input, where the uncertainty is assumed unknown. The main results of this paper are divided into three phases. In the first phase, we propose a new sliding surface is derived within the Linear Matrix Inequalities (LMIs). In the second phase, using the new sliding surface, the novel Robust Sliding Mode Control (RSMC) is proposed where the upper bound of uncertainty is supposed known. Finally, the novel approach of Robust Adaptive Sliding ModeControl (RASMC) has been defined for this type of systems, where the upper limit of uncertainty which is assumed unknown. In this new approach, we have estimate the upper limit of uncertainties and we have determined the control law based on a sliding surface that will converge to zero. This novel control laws are been validated in simulation on an uncertain numerical system with good results and comparative study. This efficiency is emphasized through the application of the new controls on the two physical systems which are the process trainer PT326 and hydraulic system two tanks. Published by Elsevier Ltd.

The evolving role of supply chain management technology in healthcare.

PubMed

Langabeer, Jim

2005-01-01

The healthcare supply chain is a vast, disintegrated network of products and players, loosely held together by manual and people-intensive processes. Managing the flow of information, supplies, equipment, and services from manufacturers to distributors to providers of care is especially difficult in clinical supply chains, compared with more technology-intense industries like consumer goods or industrial manufacturing. As supplies move downstream towards hospitals and clinics, the quality and robustness of accompanying management and information systems used to manage these products deteriorates significantly. Technology that provides advanced planning, synchronization, and collaboration upstream at the large supply manufacturers and distributors rarely is used at even the world's larger and more sophisticated hospitals. This article outlines the current state of healthcare supply chain management technologies, addresses potential reasons for the lack of adoption of technologies and provides a roadmap for the evolution of technology for the future. This piece is based on both quantitative and qualitative research assessments of the healthcare supply chain conducted during the last two years.

Simple physics-based analytical formulas for the potentials of mean force of the interaction of amino-acid side chains in water. V. Like-charged side chains.

PubMed

Makowski, Mariusz; Liwo, Adam; Sobolewski, Emil; Scheraga, Harold A

2011-05-19

A new model of side-chain-side-chain interactions for charged side-chains of amino acids, to be used in the UNRES force-field, has been developed, in which a side chain consists of a nonpolar and a charged site. The interaction energy between the nonpolar sites is composed of a Gay-Berne and a cavity term; the interaction energy between the charged sites consists of a Lennard-Jones term, a Coulombic term, a generalized-Born term, and a cavity term, while the interaction energy between the nonpolar and charged sites is composed of a Gay-Berne and a polarization term. We parametrized the energy function for the models of all six pairs of natural like-charged amino-acid side chains, namely propionate-propionate (for the aspartic acid-aspartic acid pair), butyrate-butyrate (for the glutamic acid-glutamic acid pair), propionate-butyrate (for the aspartic acid-glutamic acid pair), pentylamine cation-pentylamine cation (for the lysine-lysine pair), 1-butylguanidine cation-1-butylguanidine cation (for the arginine-arginine pair), and pentylamine cation-1-butylguanidine cation (for the lysine-arginine pair). By using umbrella-sampling molecular dynamics simulations in explicit TIP3P water, we determined the potentials of mean force of the above-mentioned pairs as functions of distance and orientation and fitted analytical expressions to them. The positions and depths of the contact minima and the positions and heights of the desolvation maxima, including their dependence on the orientation of the molecules were well represented by analytical expressions for all systems. The values of the parameters of all the energy components are physically reasonable, which justifies use of such potentials in coarse-grain protein-folding simulations. © 2011 American Chemical Society

Revealing hidden antiferromagnetic correlations in doped Hubbard chains via string correlators

NASA Astrophysics Data System (ADS)

Hilker, Timon A.; Salomon, Guillaume; Grusdt, Fabian; Omran, Ahmed; Boll, Martin; Demler, Eugene; Bloch, Immanuel; Gross, Christian

2017-08-01

Topological phases, like the Haldane phase in spin-1 chains, defy characterization through local order parameters. Instead, nonlocal string order parameters can be employed to reveal their hidden order. Similar diluted magnetic correlations appear in doped one-dimensional lattice systems owing to the phenomenon of spin-charge separation. Here we report on the direct observation of such hidden magnetic correlations via quantum gas microscopy of hole-doped ultracold Fermi-Hubbard chains. The measurement of nonlocal spin-density correlation functions reveals a hidden finite-range antiferromagnetic order, a direct consequence of spin-charge separation. Our technique, which measures nonlocal order directly, can be readily extended to higher dimensions to study the complex interplay between magnetic order and density fluctuations.

Learning to integrate reactivity and deliberation in uncertain planning and scheduling problems

NASA Technical Reports Server (NTRS)

Chien, Steve A.; Gervasio, Melinda T.; Dejong, Gerald F.

1992-01-01

This paper describes an approach to planning and scheduling in uncertain domains. In this approach, a system divides a task on a goal by goal basis into reactive and deliberative components. Initially, a task is handled entirely reactively. When failures occur, the system changes the reactive/deliverative goal division by moving goals into the deliberative component. Because our approach attempts to minimize the number of deliberative goals, we call our approach Minimal Deliberation (MD). Because MD allows goals to be treated reactively, it gains some of the advantages of reactive systems: computational efficiency, the ability to deal with noise and non-deterministic effects, and the ability to take advantage of unforseen opportunities. However, because MD can fall back upon deliberation, it can also provide some of the guarantees of classical planning, such as the ability to deal with complex goal interactions. This paper describes the Minimal Deliberation approach to integrating reactivity and deliberation and describe an ongoing application of the approach to an uncertain planning and scheduling domain.

Prediction-error variance in Bayesian model updating: a comparative study

NASA Astrophysics Data System (ADS)

Asadollahi, Parisa; Li, Jian; Huang, Yong

2017-04-01

In Bayesian model updating, the likelihood function is commonly formulated by stochastic embedding in which the maximum information entropy probability model of prediction error variances plays an important role and it is Gaussian distribution subject to the first two moments as constraints. The selection of prediction error variances can be formulated as a model class selection problem, which automatically involves a trade-off between the average data-fit of the model class and the information it extracts from the data. Therefore, it is critical for the robustness in the updating of the structural model especially in the presence of modeling errors. To date, three ways of considering prediction error variances have been seem in the literature: 1) setting constant values empirically, 2) estimating them based on the goodness-of-fit of the measured data, and 3) updating them as uncertain parameters by applying Bayes' Theorem at the model class level. In this paper, the effect of different strategies to deal with the prediction error variances on the model updating performance is investigated explicitly. A six-story shear building model with six uncertain stiffness parameters is employed as an illustrative example. Transitional Markov Chain Monte Carlo is used to draw samples of the posterior probability density function of the structure model parameters as well as the uncertain prediction variances. The different levels of modeling uncertainty and complexity are modeled through three FE models, including a true model, a model with more complexity, and a model with modeling error. Bayesian updating is performed for the three FE models considering the three aforementioned treatments of the prediction error variances. The effect of number of measurements on the model updating performance is also examined in the study. The results are compared based on model class assessment and indicate that updating the prediction error variances as uncertain parameters at the model class level produces more robust results especially when the number of measurement is small.

Architectural Insights into the Origin of Hot Jupiters

NASA Astrophysics Data System (ADS)

Schlaufman, Kevin C.; Winn, Joshua

2015-12-01

The origin of Jupiter-mass planets with orbital periods of only a few days is still uncertain. This problem has been with us for 20 years, long enough for significant progress to have been made, and also for a great deal of "lore" to have accumulated about the properties of these planets. Among this lore is the widespread belief that hot Jupiters are less likely be in multiple giant planet systems than longer-period giant planets. We will show that in this case the lore is not supported by the best data available today: hot Jupiters are no more or less likely than warm or cool Jupiters to have additional Jupiter-mass companions. In contrast to the expectation from the simplest models of high-eccentricity migration, the result holds for Jupiter-mass companions both inside and outside of the water-ice line. This support the importance of disk migration for the origin of short-period giant planets.

H∞ output tracking control of uncertain and disturbed nonlinear systems based on neural network model

NASA Astrophysics Data System (ADS)

Li, Chengcheng; Li, Yuefeng; Wang, Guanglin

2017-07-01

The work presented in this paper seeks to address the tracking problem for uncertain continuous nonlinear systems with external disturbances. The objective is to obtain a model that uses a reference-based output feedback tracking control law. The control scheme is based on neural networks and a linear difference inclusion (LDI) model, and a PDC structure and H∞ performance criterion are used to attenuate external disturbances. The stability of the whole closed-loop model is investigated using the well-known quadratic Lyapunov function. The key principles of the proposed approach are as follows: neural networks are first used to approximate nonlinearities, to enable a nonlinear system to then be represented as a linearised LDI model. An LMI (linear matrix inequality) formula is obtained for uncertain and disturbed linear systems. This formula enables a solution to be obtained through an interior point optimisation method for some nonlinear output tracking control problems. Finally, simulations and comparisons are provided on two practical examples to illustrate the validity and effectiveness of the proposed method.

Output Feedback-Based Boundary Control of Uncertain Coupled Semilinear Parabolic PDE Using Neurodynamic Programming.

PubMed

Talaei, Behzad; Jagannathan, Sarangapani; Singler, John

2018-04-01

In this paper, neurodynamic programming-based output feedback boundary control of distributed parameter systems governed by uncertain coupled semilinear parabolic partial differential equations (PDEs) under Neumann or Dirichlet boundary control conditions is introduced. First, Hamilton-Jacobi-Bellman (HJB) equation is formulated in the original PDE domain and the optimal control policy is derived using the value functional as the solution of the HJB equation. Subsequently, a novel observer is developed to estimate the system states given the uncertain nonlinearity in PDE dynamics and measured outputs. Consequently, the suboptimal boundary control policy is obtained by forward-in-time estimation of the value functional using a neural network (NN)-based online approximator and estimated state vector obtained from the NN observer. Novel adaptive tuning laws in continuous time are proposed for learning the value functional online to satisfy the HJB equation along system trajectories while ensuring the closed-loop stability. Local uniformly ultimate boundedness of the closed-loop system is verified by using Lyapunov theory. The performance of the proposed controller is verified via simulation on an unstable coupled diffusion reaction process.

Design of lipid-based formulations for oral administration of poorly water-soluble drug fenofibrate: effects of digestion.

PubMed

Mohsin, Kazi

2012-06-01

Lipid-based drug carriers are likely to have influence on bioavailability through enhanced solubilization of the drug in the gastrointestinal tract. The study was designed to investigate the lipid formulation digestibility in the simulated gastro intestinal media. Fenofibrate was formulated in representative Type II, IIIA, IIIB and IV self-emulsifying/microemulsifying lipid delivery systems (SEDDS and SMEDDS designed for oral administration) using various medium-chain glyceride components, non-ionic surfactants and cosolvents as excipients. Soybean oil was used only as an example of long-chain triglycerides to compare the effects of formulation with their counterparts. The formulations were subjected to in vitro digestion specifically to predict the fate of the drug in the gastro intestinal tract after exposure of the formulation to pancreatic enzymes and bile. In vitro digestion experiments were carried out using a pH-stat maintained at pH 7.5 for 30 min using intestinal fluids simulating the fed and fasted states. The digestion rate was faster and almost completed in Type II and IIIA systems. Most of the surfactants used in the studies are digestible. However, the high concentration of surfactant and/or cosolvent used in Type IIIB or IV systems lowered the rate of digestion. The digestion of medium-chain triglycerides was faster than long-chain triglycerides, but kept comparatively less drug in the post digestion products. Medium-chain mixed glycerides are good solvents for fenofibrate as rapidly digested but to improve fenofibrate concentration in post digestion products the use of long-chain mixed glycerides are suggested for further investigations.

Integration of internet of things to reduce various losses of jatropha seed supply chain

NASA Astrophysics Data System (ADS)

Srinivasan, S. P.; Anitha, J.; Vijayakumar, R.

2017-06-01

The evolution of bio fuel supply chain has revolutionized the organization by restructuring the practices of the traditional management. A flexible distribution system is becoming the need of our society. The main focus of this paper is to integrate IoT technologies into a cultivation, extraction and management of Jatropha seed. It was noticed that major set-back of farmers due to poor supply chain integration. The various losses like information about the Jatropha seed availability, the location of esterification plants and distribution details are identified through this IoT. This enables the farmers to reorganize the land resources, yield estimation and distribution functions. The wastage and the scarcity of energy can be tackled by using the smart phone technologies. This paper is proposes a conceptual frame work on various losses involved in the supply chain of Jatropha seed.

Symplectic integration of closed chain rigid body dynamics with internal coordinate equations of motion

NASA Astrophysics Data System (ADS)

Mazur, Alexey K.

1999-07-01

Internal coordinate molecular dynamics (ICMD) is a recent efficient method for modeling polymer molecules which treats them as chains of rigid bodies rather than ensembles of point particles as in Cartesian MD. Unfortunately, it is readily applicable only to linear or tree topologies without closed flexible loops. Important examples violating this condition are sugar rings of nucleic acids, proline residues in proteins, and also disulfide bridges. This paper presents the first complete numerical solution of the chain closure problem within the context of ICMD. The method combines natural implicit fixation of bond lengths and bond angles by the choice of internal coordinates with explicit constraints similar to Cartesian dynamics used to maintain the chain closure. It is affordable for large molecules and makes possible 3-5 times faster dynamics simulations of molecular systems with flexible rings, including important biological objects like nucleic acids and disulfide-bonded proteins.

The transiting dust clumps in the evolved disc of the Sun-like UXor RZ Psc

PubMed Central

Kenworthy, Matthew A.; Pepper, Joshua; Rodriguez, Joseph E.; Siverd, Robert J.; Stassun, Keivan G.; Wyatt, Mark C.

2017-01-01

RZ Psc is a young Sun-like star, long associated with the UXor class of variable stars, which is partially or wholly dimmed by dust clumps several times each year. The system has a bright and variable infrared excess, which has been interpreted as evidence that the dimming events are the passage of asteroidal fragments in front of the host star. Here, we present a decade of optical photometry of RZ Psc and take a critical look at the asteroid belt interpretation. We show that the distribution of light curve gradients is non-uniform for deep events, which we interpret as possible evidence for an asteroidal fragment-like clump structure. However, the clumps are very likely seen above a high optical depth midplane, so the disc’s bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disc, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disc-related variability may arise because (i) any accretion streams are transparent and/or (ii) turbulence above the inner rim is normally shadowed by a flared outer disc. PMID:28280566

The transiting dust clumps in the evolved disc of the Sun-like UXor RZ Psc.

PubMed

Kennedy, Grant M; Kenworthy, Matthew A; Pepper, Joshua; Rodriguez, Joseph E; Siverd, Robert J; Stassun, Keivan G; Wyatt, Mark C

2017-01-01

RZ Psc is a young Sun-like star, long associated with the UXor class of variable stars, which is partially or wholly dimmed by dust clumps several times each year. The system has a bright and variable infrared excess, which has been interpreted as evidence that the dimming events are the passage of asteroidal fragments in front of the host star. Here, we present a decade of optical photometry of RZ Psc and take a critical look at the asteroid belt interpretation. We show that the distribution of light curve gradients is non-uniform for deep events, which we interpret as possible evidence for an asteroidal fragment-like clump structure. However, the clumps are very likely seen above a high optical depth midplane, so the disc's bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disc, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disc-related variability may arise because (i) any accretion streams are transparent and/or (ii) turbulence above the inner rim is normally shadowed by a flared outer disc.

The transiting dust clumps in the evolved disc of the Sun-like UXor RZ Psc

NASA Astrophysics Data System (ADS)

Kennedy, Grant M.; Kenworthy, Matthew A.; Pepper, Joshua; Rodriguez, Joseph E.; Siverd, Robert J.; Stassun, Keivan G.; Wyatt, Mark C.

2017-01-01

RZ Psc is a young Sun-like star, long associated with the UXor class of variable stars, which is partially or wholly dimmed by dust clumps several times each year. The system has a bright and variable infrared excess, which has been interpreted as evidence that the dimming events are the passage of asteroidal fragments in front of the host star. Here, we present a decade of optical photometry of RZ Psc and take a critical look at the asteroid belt interpretation. We show that the distribution of light curve gradients is non-uniform for deep events, which we interpret as possible evidence for an asteroidal fragment-like clump structure. However, the clumps are very likely seen above a high optical depth midplane, so the disc's bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disc, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disc-related variability may arise because (i) any accretion streams are transparent and/or (ii) turbulence above the inner rim is normally shadowed by a flared outer disc.

Free energy landscape of protein-like chains with discontinuous potentials

NASA Astrophysics Data System (ADS)

Movahed, Hanif Bayat; van Zon, Ramses; Schofield, Jeremy

2012-06-01

In this article the configurational space of two simple protein models consisting of polymers composed of a periodic sequence of four different kinds of monomers is studied as a function of temperature. In the protein models, hydrogen bond interactions, electrostatic repulsion, and covalent bond vibrations are modeled by discontinuous step, shoulder, and square-well potentials, respectively. The protein-like chains exhibit a secondary alpha helix structure in their folded states at low temperatures, and allow a natural definition of a configuration by considering which beads are bonded. Free energies and entropies of configurations are computed using the parallel tempering method in combination with hybrid Monte Carlo sampling of the canonical ensemble of the discontinuous potential system. The probability of observing the most common configuration is used to analyze the nature of the free energy landscape, and it is found that the model with the least number of possible bonds exhibits a funnel-like free energy landscape at low enough temperature for chains with fewer than 30 beads. For longer proteins, the free landscape consists of several minima, where the configuration with the lowest free energy changes significantly by lowering the temperature and the probability of observing the most common configuration never approaches one due to the degeneracy of the lowest accessible potential energy.

Stochastic Order Redshift Technique (SORT): a simple, efficient and robust method to improve cosmological redshift measurements

NASA Astrophysics Data System (ADS)

Tejos, Nicolas; Rodríguez-Puebla, Aldo; Primack, Joel R.

2018-01-01

We present a simple, efficient and robust approach to improve cosmological redshift measurements. The method is based on the presence of a reference sample for which a precise redshift number distribution (dN/dz) can be obtained for different pencil-beam-like sub-volumes within the original survey. For each sub-volume we then impose that: (i) the redshift number distribution of the uncertain redshift measurements matches the reference dN/dz corrected by their selection functions and (ii) the rank order in redshift of the original ensemble of uncertain measurements is preserved. The latter step is motivated by the fact that random variables drawn from Gaussian probability density functions (PDFs) of different means and arbitrarily large standard deviations satisfy stochastic ordering. We then repeat this simple algorithm for multiple arbitrary pencil-beam-like overlapping sub-volumes; in this manner, each uncertain measurement has multiple (non-independent) 'recovered' redshifts which can be used to estimate a new redshift PDF. We refer to this method as the Stochastic Order Redshift Technique (SORT). We have used a state-of-the-art N-body simulation to test the performance of SORT under simple assumptions and found that it can improve the quality of cosmological redshifts in a robust and efficient manner. Particularly, SORT redshifts (zsort) are able to recover the distinctive features of the so-called 'cosmic web' and can provide unbiased measurement of the two-point correlation function on scales ≳4 h-1Mpc. Given its simplicity, we envision that a method like SORT can be incorporated into more sophisticated algorithms aimed to exploit the full potential of large extragalactic photometric surveys.

An interacting O + O supergiant close binary system: Cygnus OB2-5 (V729 Cyg)

NASA Astrophysics Data System (ADS)

Yaşarsoy, B.; Yakut, K.

2014-08-01

The massive interacting close binary system V729 Cyg (OIa + O/WN9), plausibly progenitor of a Wolf-Rayet system, is studied using new observations gathered over 65 nights and earlier published data. Radial velocity and five color light curves are analysed simultaneously. Estimated physical parameters of the components are M1=36±3 M, M2=10±1 M, R1=27±1 R, R2=15±0.6 R, log(L1/L⊙)=5.59±0.06, and log(L2/L⊙)=4.65±0.07. We give only the formal 1σ scatter, but we believe systematic errors in the luminosities, of uncertain origin as discussed in the text, are likely to be much bigger. The distance of the Cygnus OB2 association is estimated as 967±48 pc by using our newly obtained parameters.

Defense system shortcuts and limits of scope.

PubMed

Rewald, E; Francischetti, M M

2000-10-01

Defense, as a key factor of life, shares the biological tendencies of simplicity and energy saving. We propose that, like the mind, defense tends to rely on shortcuts via immune memes. Also, response repetition may induce the formation of virtual 'modules' [toolkits] to simplify and perfect performance. Engaged modules may expand by proliferating or by capturing immune components from the 'dormant' and even perhaps from active ones. With regard to recovery and/or survival, complexity of the integrated defense system (IDS) (1) requires to be inside of what we call the 'functional window'. In contrast to the physiological and common disease repair, energy is squandered when IDS perceives real danger. Our concern is the uncertain transition to conditions that do not fit into the IDS routine and, even worse, that are outside the functional window where the system is lacking. Copyright 2000 Harcourt Publishers Ltd.

Expression of IGF-I, IGF-I receptor and IGF binding proteins-1, -2, -3, -4 and -5 in human atherectomy specimens.

PubMed

Grant, M B; Wargovich, T J; Ellis, E A; Tarnuzzer, R; Caballero, S; Estes, K; Rossing, M; Spoerri, P E; Pepine, C

1996-12-17

The molecular and cellular processes that induce rapid atherosclerotic plaque progression in patients with unstable angina and initiate restenosis following coronary interventional procedures are uncertain. We examined primary (de novo) and restenotic lesions retrieved at the time of directional coronary atherectomy for expression of insulin-like-growth factor-I (IGF-I). IGF-I receptor, and five IGF binding proteins (IGFBPs), IGFBP-1, IGFBP-2, IGFBP-3, IGFBP-4, and IGFBP-5 in smooth muscle cells (SMCs) using colloidal gold immunocytochemistry. IGF-1, its receptor and binding proteins were not detected in SMCs of normal coronary arteries. IGF-I localized primarily in synthetic smooth muscle cells (sSMCs) in both de novo and restenotic plaques. IGF-I receptor localized on sSMCs and their processes and colocalized with IGF-I. Although morphometric analysis of IGF-I and IGF-I receptor immunoreactivity in sSMCs of de novo and restenotic lesions showed comparable levels of IGF-I (3.2 +/- 1.0 and 2.9 +/- 0.9, respectively). IGF-I receptor was significantly higher in de novo lesions as compared to restenotic lesions (10.7 +/- 2.5 and 4.2 +/- 1.3, P < 0.05, respectively). IGFBP-1, IGFBP-2, IGFBP-3, IGFBP-4 and IGFBP-5 localized in the cytoplasm of sSMCs and in the extracellular matrix. Quantitative reverse transcription polymerase chain reaction (QRT-PCR) performed on de novo atherectomy specimens identified mRNA for IGF-I, IGF-I receptor, IGFBP-1, IGFBP-2, IGFBP-4, IGFBP-5 levels and detected mRNA for IGFBP-3. The expression of IGF-I, IGF-I receptor, and IGFBPs in atherectomy plaques suggests that the development of coronary obstructive lesions may be a result of changes in the IGF system.

Ga-67 positivity in sarcoidosis of the skin with coincident thyroid uptake of uncertain etiology

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

Moreno, A.J.; Brown, J.M.; Salinas, J.A.

1984-03-01

Gallium-67 citrate scintigraphy of a 26-year-old woman with systemic sarcoidosis demonstrated abnormal radiotracer uptake within multiple biopsy-proven sarcoidal cutaneous lesions and within both lobes of the thyroid gland. The etiology of the thyroidal uptake of the Ga-67 was uncertain but it may represent sarcoidal involvement of the gland.

Adaptive fixed-time control for cluster synchronisation of coupled complex networks with uncertain disturbances

NASA Astrophysics Data System (ADS)

Jiang, Shengqin; Lu, Xiaobo; Cai, Guoliang; Cai, Shuiming

2017-12-01

This paper focuses on the cluster synchronisation problem of coupled complex networks with uncertain disturbances under an adaptive fixed-time control strategy. To begin with, complex dynamical networks with community structure which are subject to uncertain disturbances are taken into account. Then, a novel adaptive control strategy combined with fixed-time techniques is proposed to guarantee the nodes in the communities to desired states in a settling time. In addition, the stability of complex error systems is theoretically proved based on Lyapunov stability theorem. At last, two examples are presented to verify the effectiveness of the proposed adaptive fixed-time control.

Application of dynamic uncertain causality graph in spacecraft fault diagnosis: Logic cycle

NASA Astrophysics Data System (ADS)

Yao, Quanying; Zhang, Qin; Liu, Peng; Yang, Ping; Zhu, Ma; Wang, Xiaochen

2017-04-01

Intelligent diagnosis system are applied to fault diagnosis in spacecraft. Dynamic Uncertain Causality Graph (DUCG) is a new probability graphic model with many advantages. In the knowledge expression of spacecraft fault diagnosis, feedback among variables is frequently encountered, which may cause directed cyclic graphs (DCGs). Probabilistic graphical models (PGMs) such as bayesian network (BN) have been widely applied in uncertain causality representation and probabilistic reasoning, but BN does not allow DCGs. In this paper, DUGG is applied to fault diagnosis in spacecraft: introducing the inference algorithm for the DUCG to deal with feedback. Now, DUCG has been tested in 16 typical faults with 100% diagnosis accuracy.

The Publishing Culture and the Literary Culture.

ERIC Educational Resources Information Center

Solotaroff, Ted

1984-01-01

Argues that traditional bridges between the literary culture and publishing culture have increasingly weakened in past decade. The publishing culture has become like that of big business, marked by effort to standardize product, distribution, and consumer, and the advent of bookstore chains has put into practice the mass-merchandising system.…

Opposed Bellows Would Expel Contents Of Tank

NASA Technical Reports Server (NTRS)

Whitaker, Willie

1994-01-01

Proposed storage tank contains two pairs of opposed bellows used to expel its contents. Storage and expulsion volumes of tank same as those of older version of tank equipped with single bellows. Four bellows offer greater stability. Applications include automobile cooling systems and gasoline-powered tools like chain saws and leaf blowers.

Event-Based Robust Control for Uncertain Nonlinear Systems Using Adaptive Dynamic Programming.

PubMed

Zhang, Qichao; Zhao, Dongbin; Wang, Ding

2018-01-01

In this paper, the robust control problem for a class of continuous-time nonlinear system with unmatched uncertainties is investigated using an event-based control method. First, the robust control problem is transformed into a corresponding optimal control problem with an augmented control and an appropriate cost function. Under the event-based mechanism, we prove that the solution of the optimal control problem can asymptotically stabilize the uncertain system with an adaptive triggering condition. That is, the designed event-based controller is robust to the original uncertain system. Note that the event-based controller is updated only when the triggering condition is satisfied, which can save the communication resources between the plant and the controller. Then, a single network adaptive dynamic programming structure with experience replay technique is constructed to approach the optimal control policies. The stability of the closed-loop system with the event-based control policy and the augmented control policy is analyzed using the Lyapunov approach. Furthermore, we prove that the minimal intersample time is bounded by a nonzero positive constant, which excludes Zeno behavior during the learning process. Finally, two simulation examples are provided to demonstrate the effectiveness of the proposed control scheme.

Thermomechanical Properties and Glass Dynamics of Polymer-Tethered Colloidal Particles and Films

PubMed Central

2017-01-01

Polymer-tethered colloidal particles (aka “particle brush materials”) have attracted interest as a platform for innovative material technologies and as a model system to elucidate glass formation in complex structured media. In this contribution, Brillouin light scattering is used to sequentially evaluate the role of brush architecture on the dynamical properties of brush particles in both the individual and assembled (film) state. In the former state, the analysis reveals that brush–brush interactions as well as global chain relaxation sensitively depend on grafting density; i.e., more polymer-like behavior is observed in sparse brush systems. This is interpreted to be a consequence of more extensive chain entanglement. In contrast, the local relaxation of films does not depend on grafting density. The results highlight that relaxation processes in particle brush-based materials span a wider range of time and length scales as compared to linear chain polymers. Differentiation between relaxation on local and global scale is necessary to reveal the influence of molecular structure and connectivity on the aging behavior of these complex systems. PMID:29755139

Thermomechanical Properties and Glass Dynamics of Polymer-Tethered Colloidal Particles and Films.

PubMed

Cang, Yu; Reuss, Anna N; Lee, Jaejun; Yan, Jiajun; Zhang, Jianan; Alonso-Redondo, Elena; Sainidou, Rebecca; Rembert, Pascal; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Fytas, George

2017-11-14

Polymer-tethered colloidal particles (aka "particle brush materials") have attracted interest as a platform for innovative material technologies and as a model system to elucidate glass formation in complex structured media. In this contribution, Brillouin light scattering is used to sequentially evaluate the role of brush architecture on the dynamical properties of brush particles in both the individual and assembled (film) state. In the former state, the analysis reveals that brush-brush interactions as well as global chain relaxation sensitively depend on grafting density; i.e., more polymer-like behavior is observed in sparse brush systems. This is interpreted to be a consequence of more extensive chain entanglement. In contrast, the local relaxation of films does not depend on grafting density. The results highlight that relaxation processes in particle brush-based materials span a wider range of time and length scales as compared to linear chain polymers. Differentiation between relaxation on local and global scale is necessary to reveal the influence of molecular structure and connectivity on the aging behavior of these complex systems.

Transducer placement for robustness to variations in boundary conditions for active structural acoustic control

NASA Astrophysics Data System (ADS)

Sprofera, Joseph D.; Clark, Robert L.; Cabell, Randolph H.; Gibbs, Gary P.

2005-05-01

Turbulent boundary layer (TBL) noise is considered a primary contribution to the interior noise present in commercial airliners. There are numerous investigations of interior noise control devoted to aircraft panels; however, practical realization is a potential challenge since physical boundary conditions are uncertain at best. In most prior studies, pinned or clamped boundary conditions were assumed; however, realistic panels likely display a range of boundary conditions between these two limits. Uncertainty in boundary conditions is a challenge for control system designers, both in terms of the compensator implemented and the location of transducers required to achieve the desired control. The impact of model uncertainties, specifically uncertain boundaries, on the selection of transducer locations for structural acoustic control is considered herein. The final goal of this work is the design of an aircraft panel structure that can reduce TBL noise transmission through the use of a completely adaptive, single-input, single-output control system. The feasibility of this goal is demonstrated through the creation of a detailed analytical solution, followed by the implementation of a test model in a transmission loss apparatus. Successfully realizing a control system robust to variations in boundary conditions can lead to the design and implementation of practical adaptive structures that could be used to control the transmission of sound to the interior of aircraft. Results from this research effort indicate it is possible to optimize the design of actuator and sensor location and aperture, minimizing the impact of boundary conditions on the desired structural acoustic control.

Synthesis and Self-Assembly of Cellulose Microfibrils from Reconstituted Cellulose Synthase.

PubMed

Cho, Sung Hyun; Purushotham, Pallinti; Fang, Chao; Maranas, Cassandra; Díaz-Moreno, Sara M; Bulone, Vincent; Zimmer, Jochen; Kumar, Manish; Nixon, B Tracy

2017-09-01

Cellulose, the major component of plant cell walls, can be converted to bioethanol and is thus highly studied. In plants, cellulose is produced by cellulose synthase, a processive family-2 glycosyltransferase. In plant cell walls, individual β-1,4-glucan chains polymerized by CesA are assembled into microfibrils that are frequently bundled into macrofibrils. An in vitro system in which cellulose is synthesized and assembled into fibrils would facilitate detailed study of this process. Here, we report the heterologous expression and partial purification of His-tagged CesA5 from Physcomitrella patens Immunoblot analysis and mass spectrometry confirmed enrichment of PpCesA5. The recombinant protein was functional when reconstituted into liposomes made from yeast total lipid extract. The functional studies included incorporation of radiolabeled Glc, linkage analysis, and imaging of cellulose microfibril formation using transmission electron microscopy. Several microfibrils were observed either inside or on the outer surface of proteoliposomes, and strikingly, several thinner fibrils formed ordered bundles that either covered the surfaces of proteoliposomes or were spawned from liposome surfaces. We also report this arrangement of fibrils made by proteoliposomes bearing CesA8 from hybrid aspen. These observations describe minimal systems of membrane-reconstituted CesAs that polymerize β-1,4-glucan chains that coalesce to form microfibrils and higher-ordered macrofibrils. How these micro- and macrofibrils relate to those found in primary and secondary plant cell walls is uncertain, but their presence enables further study of the mechanisms that govern the formation and assembly of fibrillar cellulosic structures and cell wall composites during or after the polymerization process controlled by CesA proteins. © 2017 American Society of Plant Biologists. All Rights Reserved.

Synthesis and Self-Assembly of Cellulose Microfibrils from Reconstituted Cellulose Synthase1[OPEN

PubMed Central

Purushotham, Pallinti; Fang, Chao; Maranas, Cassandra; Bulone, Vincent

2017-01-01

Cellulose, the major component of plant cell walls, can be converted to bioethanol and is thus highly studied. In plants, cellulose is produced by cellulose synthase, a processive family-2 glycosyltransferase. In plant cell walls, individual β-1,4-glucan chains polymerized by CesA are assembled into microfibrils that are frequently bundled into macrofibrils. An in vitro system in which cellulose is synthesized and assembled into fibrils would facilitate detailed study of this process. Here, we report the heterologous expression and partial purification of His-tagged CesA5 from Physcomitrella patens. Immunoblot analysis and mass spectrometry confirmed enrichment of PpCesA5. The recombinant protein was functional when reconstituted into liposomes made from yeast total lipid extract. The functional studies included incorporation of radiolabeled Glc, linkage analysis, and imaging of cellulose microfibril formation using transmission electron microscopy. Several microfibrils were observed either inside or on the outer surface of proteoliposomes, and strikingly, several thinner fibrils formed ordered bundles that either covered the surfaces of proteoliposomes or were spawned from liposome surfaces. We also report this arrangement of fibrils made by proteoliposomes bearing CesA8 from hybrid aspen. These observations describe minimal systems of membrane-reconstituted CesAs that polymerize β-1,4-glucan chains that coalesce to form microfibrils and higher-ordered macrofibrils. How these micro- and macrofibrils relate to those found in primary and secondary plant cell walls is uncertain, but their presence enables further study of the mechanisms that govern the formation and assembly of fibrillar cellulosic structures and cell wall composites during or after the polymerization process controlled by CesA proteins. PMID:28768815

Statistical Maps of Ground Magnetic Disturbance Derived from Global Geospace Models

NASA Astrophysics Data System (ADS)

Rigler, E. J.; Wiltberger, M. J.; Love, J. J.

2017-12-01

Electric currents in space are the principal driver of magnetic variations measured at Earth's surface. These in turn induce geoelectric fields that present a natural hazard for technological systems like high-voltage power distribution networks. Modern global geospace models can reasonably simulate large-scale geomagnetic response to solar wind variations, but they are less successful at deterministic predictions of intense localized geomagnetic activity that most impacts technological systems on the ground. Still, recent studies have shown that these models can accurately reproduce the spatial statistical distributions of geomagnetic activity, suggesting that their physics are largely correct. Since the magnetosphere is a largely externally driven system, most model-measurement discrepancies probably arise from uncertain boundary conditions. So, with realistic distributions of solar wind parameters to establish its boundary conditions, we use the Lyon-Fedder-Mobarry (LFM) geospace model to build a synthetic multivariate statistical model of gridded ground magnetic disturbance. From this, we analyze the spatial modes of geomagnetic response, regress on available measurements to fill in unsampled locations on the grid, and estimate the global probability distribution of extreme magnetic disturbance. The latter offers a prototype geomagnetic "hazard map", similar to those used to characterize better-known geophysical hazards like earthquakes and floods.

Identifying Model-Based Reconfiguration Goals through Functional Deficiencies

NASA Technical Reports Server (NTRS)

Benazera, Emmanuel; Trave-Massuyes, Louise

2004-01-01

Model-based diagnosis is now advanced to the point autonomous systems face some uncertain and faulty situations with success. The next step toward more autonomy is to have the system recovering itself after faults occur, a process known as model-based reconfiguration. After faults occur, given a prediction of the nominal behavior of the system and the result of the diagnosis operation, this paper details how to automatically determine the functional deficiencies of the system. These deficiencies are characterized in the case of uncertain state estimates. A methodology is then presented to determine the reconfiguration goals based on the deficiencies. Finally, a recovery process interleaves planning and model predictive control to restore the functionalities in prioritized order.

Design of Distributed Engine Control Systems with Uncertain Delay.

PubMed

Liu, Xiaofeng; Li, Yanxi; Sun, Xu

Future gas turbine engine control systems will be based on distributed architecture, in which, the sensors and actuators will be connected to the controllers via a communication network. The performance of the distributed engine control (DEC) is dependent on the network performance. This study introduces a distributed control system architecture based on a networked cascade control system (NCCS). Typical turboshaft engine-distributed controllers are designed based on the NCCS framework with a H∞ output feedback under network-induced time delays and uncertain disturbances. The sufficient conditions for robust stability are derived via the Lyapunov stability theory and linear matrix inequality approach. Both numerical and hardware-in-loop simulations illustrate the effectiveness of the presented method.

Computer program for single input-output, single-loop feedback systems

NASA Technical Reports Server (NTRS)

1976-01-01

Additional work is reported on a completely automatic computer program for the design of single input/output, single loop feedback systems with parameter uncertainly, to satisfy time domain bounds on the system response to step commands and disturbances. The inputs to the program are basically the specified time-domain response bounds, the form of the constrained plant transfer function and the ranges of the uncertain parameters of the plant. The program output consists of the transfer functions of the two free compensation networks, in the form of the coefficients of the numerator and denominator polynomials, and the data on the prescribed bounds and the extremes actually obtained for the system response to commands and disturbances.

Design of Distributed Engine Control Systems with Uncertain Delay

PubMed Central

Li, Yanxi; Sun, Xu

2016-01-01

Future gas turbine engine control systems will be based on distributed architecture, in which, the sensors and actuators will be connected to the controllers via a communication network. The performance of the distributed engine control (DEC) is dependent on the network performance. This study introduces a distributed control system architecture based on a networked cascade control system (NCCS). Typical turboshaft engine-distributed controllers are designed based on the NCCS framework with a H∞ output feedback under network-induced time delays and uncertain disturbances. The sufficient conditions for robust stability are derived via the Lyapunov stability theory and linear matrix inequality approach. Both numerical and hardware-in-loop simulations illustrate the effectiveness of the presented method. PMID:27669005

Methods for assessment of keel bone damage in poultry.

PubMed

Casey-Trott, T; Heerkens, J L T; Petrik, M; Regmi, P; Schrader, L; Toscano, M J; Widowski, T

2015-10-01

Keel bone damage (KBD) is a critical issue facing the laying hen industry today as a result of the likely pain leading to compromised welfare and the potential for reduced productivity. Recent reports suggest that damage, while highly variable and likely dependent on a host of factors, extends to all systems (including battery cages, furnished cages, and non-cage systems), genetic lines, and management styles. Despite the extent of the problem, the research community remains uncertain as to the causes and influencing factors of KBD. Although progress has been made investigating these factors, the overall effort is hindered by several issues related to the assessment of KBD, including quality and variation in the methods used between research groups. These issues prevent effective comparison of studies, as well as difficulties in identifying the presence of damage leading to poor accuracy and reliability. The current manuscript seeks to resolve these issues by offering precise definitions for types of KBD, reviewing methods for assessment, and providing recommendations that can improve the accuracy and reliability of those assessments. © 2015 Poultry Science Association Inc.

Decomposition-Based Decision Making for Aerospace Vehicle Design

NASA Technical Reports Server (NTRS)

Borer, Nicholas K.; Mavris, DImitri N.

2005-01-01

Most practical engineering systems design problems have multiple and conflicting objectives. Furthermore, the satisfactory attainment level for each objective ( requirement ) is likely uncertain early in the design process. Systems with long design cycle times will exhibit more of this uncertainty throughout the design process. This is further complicated if the system is expected to perform for a relatively long period of time, as now it will need to grow as new requirements are identified and new technologies are introduced. These points identify a need for a systems design technique that enables decision making amongst multiple objectives in the presence of uncertainty. Traditional design techniques deal with a single objective or a small number of objectives that are often aggregates of the overarching goals sought through the generation of a new system. Other requirements, although uncertain, are viewed as static constraints to this single or multiple objective optimization problem. With either of these formulations, enabling tradeoffs between the requirements, objectives, or combinations thereof is a slow, serial process that becomes increasingly complex as more criteria are added. This research proposal outlines a technique that attempts to address these and other idiosyncrasies associated with modern aerospace systems design. The proposed formulation first recasts systems design into a multiple criteria decision making problem. The now multiple objectives are decomposed to discover the critical characteristics of the objective space. Tradeoffs between the objectives are considered amongst these critical characteristics by comparison to a probabilistic ideal tradeoff solution. The proposed formulation represents a radical departure from traditional methods. A pitfall of this technique is in the validation of the solution: in a multi-objective sense, how can a decision maker justify a choice between non-dominated alternatives? A series of examples help the reader to observe how this technique can be applied to aerospace systems design and compare the results of this so-called Decomposition-Based Decision Making to more traditional design approaches.

Power Terminal Communication Access Network Monitoring System Scheme Based on Design Patterns

NASA Astrophysics Data System (ADS)

Yan, Shengchao; Wu, Desheng; Zhu, Jiang

2018-01-01

In order to realize patterns design for terminal communication monitoring system, this paper introduces manager-workers, tasks-workers design patterns, based on common design patterns such as factory method, chain of responsibility, facade. Using these patterns, the communication monitoring system which combines module-groups like networking communication, business data processing and the peripheral support has been designed successfully. Using these patterns makes this system have great flexibility and scalability and improves the degree of systematic pattern design structure.

Evaluating the value proposition for improving vaccine thermostability to increase vaccine impact in low and middle-income countries.

PubMed

Karp, Christopher L; Lans, Deborah; Esparza, José; Edson, Eleanore B; Owen, Katey E; Wilson, Christopher B; Heaton, Penny M; Levine, Orin S; Rao, Raja

2015-07-09

The need to keep vaccines cold in the face of high ambient temperatures and unreliable access to electricity is a challenge that limits vaccine coverage in low and middle-income countries (LMICs). Greater vaccine thermostability is generally touted as the obvious solution. Despite conventional wisdom, comprehensive analysis of the value proposition for increasing vaccine thermostability has been lacking. Further, while significant investments have been made in increasing vaccine thermostability in recent years, no vaccine products have been commercialized as a result. We analyzed the value proposition for increasing vaccine thermostability, grounding the analysis in specific vaccine use cases (e.g., use in routine immunization [RI] programs, or in campaigns) and in the broader context of cold chain technology and country level supply chain system design. The results were often surprising. For example, cold chain costs actually represent a relatively small fraction of total vaccine delivery system costs. Further, there are critical, vaccine use case-specific temporal thresholds that need to be overcome for significant benefits to be reaped from increasing vaccine thermostability. We present a number of recommendations deriving from this analysis that suggest a rational path toward unlocking the value (maximizing coverage, minimizing total system costs) of increased vaccine thermostability, including: (1) the full range of thermostability of existing vaccines should be defined and included in their labels; (2) for new vaccines, thermostability goals should be addressed up-front at the level of the target product profile; (3) improving cold chain infrastructure and supply chain system design is likely to have the largest impact on total system costs and coverage in the short term-and will influence the degree of thermostability required in the future; (4) in the long term, there remains value in monitoring the emergence of disruptive technologies that could remove the entire RI portfolio out of the cold chain. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Transient Stability Assessment of Power Systems With Uncertain Renewable Generation: Preprint

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

Villegas Pico, Hugo Nestor; Aliprantis, Dionysios C.; Lin, Xiaojun

2017-08-09

The transient stability of a power system depends heavily on its operational state at the moment of a fault. In systems where the penetration of renewable generation is significant, the dispatch of the conventional fleet of synchronous generators is uncertain at the time of dynamic security analysis. Hence, the assessment of transient stability requires the solution of a system of nonlinear ordinary differential equations with unknown initial conditions and inputs. To this end, we set forth a computational framework that relies on Taylor polynomials, where variables are associated with the level of renewable generation. This paper describes the details ofmore » the method and illustrates its application on a nine-bus test system.« less

Supply Chain Vulnerability Analysis Using Scenario-Based Input-Output Modeling: Application to Port Operations.

PubMed

Thekdi, Shital A; Santos, Joost R

2016-05-01

Disruptive events such as natural disasters, loss or reduction of resources, work stoppages, and emergent conditions have potential to propagate economic losses across trade networks. In particular, disruptions to the operation of container port activity can be detrimental for international trade and commerce. Risk assessment should anticipate the impact of port operation disruptions with consideration of how priorities change due to uncertain scenarios and guide investments that are effective and feasible for implementation. Priorities for protective measures and continuity of operations planning must consider the economic impact of such disruptions across a variety of scenarios. This article introduces new performance metrics to characterize resiliency in interdependency modeling and also integrates scenario-based methods to measure economic sensitivity to sudden-onset disruptions. The methods will be demonstrated on a U.S. port responsible for handling $36.1 billion of cargo annually. The methods will be useful to port management, private industry supply chain planning, and transportation infrastructure management. © 2015 Society for Risk Analysis.

Design of sliding-mode observer for a class of uncertain neutral stochastic systems

NASA Astrophysics Data System (ADS)

Liu, Zhen; Zhao, Lin; Zhu, Quanmin; Gao, Cunchen

2017-05-01

The problem of robust ? control for a class of uncertain neutral stochastic systems (NSS) is investigated by utilising the sliding-mode observer (SMO) technique. This paper presents a novel observer and integral-type sliding-surface design, based on which a new sufficient condition guaranteeing the resultant sliding-mode dynamics (SMDs) to be mean-square exponentially stable with a prescribed level of ? performance is derived. Then, an adaptive reaching motion controller is synthesised to lead the system to the predesigned sliding surface in finite-time almost surely. Finally, two illustrative examples are exhibited to verify the validity and superiority of the developed scheme.

Global adaptive control for uncertain nonaffine nonlinear hysteretic systems.

PubMed

Liu, Yong-Hua; Huang, Liangpei; Xiao, Dongming; Guo, Yong

2015-09-01

In this paper, the global output tracking is investigated for a class of uncertain nonlinear hysteretic systems with nonaffine structures. By combining the solution properties of the hysteresis model with the novel backstepping approach, a robust adaptive control algorithm is developed without constructing a hysteresis inverse. The proposed control scheme is further modified to tackle the bounded disturbances by adaptively estimating their bounds. It is rigorously proven that the designed adaptive controllers can guarantee global stability of the closed-loop system. Two numerical examples are provided to show the effectiveness of the proposed control schemes. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Case Western Reserve University — Treatment of Glioblastoma Using Chain-Like Nanoparticles

Cancer.gov

To overcome the limitations of current drugs to treat brain tumors, Case Western University seeks to integrate the unique features of a chain-like nanoparticle with the appropriate combination of complementary drugs.

Interactive entity resolution in relational data: a visual analytic tool and its evaluation.

PubMed

Kang, Hyunmo; Getoor, Lise; Shneiderman, Ben; Bilgic, Mustafa; Licamele, Louis

2008-01-01

Databases often contain uncertain and imprecise references to real-world entities. Entity resolution, the process of reconciling multiple references to underlying real-world entities, is an important data cleaning process required before accurate visualization or analysis of the data is possible. In many cases, in addition to noisy data describing entities, there is data describing the relationships among the entities. This relational data is important during the entity resolution process; it is useful both for the algorithms which determine likely database references to be resolved and for visual analytic tools which support the entity resolution process. In this paper, we introduce a novel user interface, D-Dupe, for interactive entity resolution in relational data. D-Dupe effectively combines relational entity resolution algorithms with a novel network visualization that enables users to make use of an entity's relational context for making resolution decisions. Since resolution decisions often are interdependent, D-Dupe facilitates understanding this complex process through animations which highlight combined inferences and a history mechanism which allows users to inspect chains of resolution decisions. An empirical study with 12 users confirmed the benefits of the relational context visualization on the performance of entity resolution tasks in relational data in terms of time as well as users' confidence and satisfaction.

Impact of targeting insulin-like growth factor signaling in head and neck cancers.

PubMed

Limesand, Kirsten H; Chibly, Alejandro Martinez; Fribley, Andrew

2013-10-01

The IGF system has been shown to have either negative or negligible impact on clinical outcomes of tumor development depending on specific tumor sites or stages. This review focuses on the clinical impact of IGF signaling in head and neck cancer, the effects of IGF targeted therapies, and the multi-dimensional role of IRS 1/2 signaling as a potential mechanism in resistance to targeted therapies. Similar to other tumor sites, both negative and positive correlations between levels of IGF-1/IGF-1-R and clinical outcomes in head and neck cancer have been reported. In addition, utilization of IGF targeted therapies has not demonstrated significant clinical benefit; therefore the prognostic impact of the IGF system on head and neck cancer remains uncertain. Copyright © 2013 Elsevier Ltd. All rights reserved.

Alternative industrial carbon emissions benchmark based on input-output analysis

NASA Astrophysics Data System (ADS)

Han, Mengyao; Ji, Xi

2016-12-01

Some problems exist in the current carbon emissions benchmark setting systems. The primary consideration for industrial carbon emissions standards highly relate to direct carbon emissions (power-related emissions) and only a portion of indirect emissions are considered in the current carbon emissions accounting processes. This practice is insufficient and may cause double counting to some extent due to mixed emission sources. To better integrate and quantify direct and indirect carbon emissions, an embodied industrial carbon emissions benchmark setting method is proposed to guide the establishment of carbon emissions benchmarks based on input-output analysis. This method attempts to link direct carbon emissions with inter-industrial economic exchanges and systematically quantifies carbon emissions embodied in total product delivery chains. The purpose of this study is to design a practical new set of embodied intensity-based benchmarks for both direct and indirect carbon emissions. Beijing, at the first level of carbon emissions trading pilot schemes in China, plays a significant role in the establishment of these schemes and is chosen as an example in this study. The newly proposed method tends to relate emissions directly to each responsibility in a practical way through the measurement of complex production and supply chains and reduce carbon emissions from their original sources. This method is expected to be developed under uncertain internal and external contexts and is further expected to be generalized to guide the establishment of industrial benchmarks for carbon emissions trading schemes in China and other countries.

Making the Transition

ERIC Educational Resources Information Center

Clark, Wayne

2011-01-01

The role of universities in contributing to lifelong learning is likely to undergo significant change in the next few years as the higher education sector grapples with the government's overhaul of university funding. Opportunities for progression to university for those studying outside of A-levels are particularly uncertain in the emerging…

Translation and assembly of HLA-DR antigens in Xenopus oocytes injected with mRNA from a human B-cell line.

PubMed Central

Long, E O; Gross, N; Wake, C T; Mach, J P; Carrel, S; Accolla, R; Mach, B

1982-01-01

HLA-DR antigens are polymorphic cell surface glycoproteins, expressed primarily in B lymphocytes and macrophages, which are thought to play an important role in the immune response. Two polypeptide chains, alpha and beta, are associated at the cell surface, and a third chain associates with alpha and beta intracellularly. RNA isolated from the human B-cell line Raji was injected in Xenopus laevis oocytes. Immunoprecipitates of translation products with several monoclonal antibodies revealed the presence of HLA-DR antigens similar to those synthesized in Raji cells. One monoclonal antibody was able to bind the beta chain after dissociation of the three polypeptide chains with detergent. The presence of all three chains was confirmed by two-dimensional gel electrophoresis. The glycosylation pattern of the three chains was identical to that observed in vivo, as evidenced in studies using tunicamycin, an inhibitor of N-linked glycosylation. The presence of alpha chains assembled with beta chains in equimolar ratio was further demonstrated by amino-terminal sequencing. An RNA fraction enriched for the three mRNAs, encoding alpha, beta, and intracellular chains, was isolated. This translation-assembly system and the availability of monoclonal antibodies make it possible to assay for mRNA encoding specific molecules among the multiple human Ia-like antigens. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. PMID:6821356

Insights into the species-specific TLR4 signaling mechanism in response to Rhodobacter sphaeroides lipid A detection

NASA Astrophysics Data System (ADS)

Anwar, Muhammad Ayaz; Panneerselvam, Suresh; Shah, Masaud; Choi, Sangdun

2015-01-01

TLR4 in complex with MD2 senses the presence of lipid A (LA) and initiates a signaling cascade that curb the infection. This complex is evolutionarily conserved and can initiate the immune system in response to a variety of LAs. In this study, molecular dynamics simulation (25 ns) was performed to elucidate the differential behavior of TLR4/MD2 complex in response to Rhodobacter sphaeroides lipid A (RsLA). Penta-acyl chain-containing RsLA is at the verge of agonist (6 acyl-chains) and antagonist (4 acyl-chains) structure, and activates the TLR4 pathway in horses and hamsters, while inhibiting in humans and murine. In the time-evolved coordinates, the promising factors that dictated the differential response included the local and global mobility pattern of complexes, solvent-accessible surface area of ligand, and surface charge distributions of TLR4 and MD2. We showed that the GlcN1-GlcN2 backbone acquires agonist (3FXI)-like configurations in horses and hamsters, while acquiring antagonist (2E59)-like configurations in humans and murine systems. Moreover, analysis of F126 behavior in the MD2 F126 loop (amino acids 123-129) and loop EF (81-89) suggested that certain sequence variations also contribute to species-specific response. This study underlines the TLR4 signaling mechanism and provides new therapeutic opportunities.

Analyzing the Effectiveness of the Self-organized Public-Key Management System on MANETs under the Lack of Cooperation and the Impersonation Attacks

NASA Astrophysics Data System (ADS)

da Silva, Eduardo; Dos Santos, Aldri Luiz; Lima, Michele N.; Albini, Luiz Carlos Pessoa

Among the key management schemes for MANETs, the Self-Organized Public-Key Management System (PGP-Like) is the main chaining-based key management scheme. It is fully self-organized and does not require any certificate authority. Two kinds of misbehavior attacks are considered to be great threats to PGP-Like: lack of cooperation and impersonation attacks. This work quantifies the impact of such attacks on the PGP-Like. Simulation results show that PGP-Like was able to maintain its effectiveness when submitted to the lack of cooperation attack, contradicting previously theoretical results. It correctly works even in the presence of more than 60% of misbehaving nodes, although the convergence time is affected with only 20% of misbehaving nodes. On the other hand, PGP-Like is completely vulnerable to the impersonation attack. Its functionality is affected with just 5% of misbehaving nodes, confirming previously theoretical results.

Effective Hamiltonian for travelling discrete breathers

NASA Astrophysics Data System (ADS)

MacKay, Robert S.; Sepulchre, Jacques-Alexandre

2002-05-01

Hamiltonian chains of oscillators in general probably do not sustain exact travelling discrete breathers. However solutions which look like moving discrete breathers for some time are not difficult to observe in numerics. In this paper we propose an abstract framework for the description of approximate travelling discrete breathers in Hamiltonian chains of oscillators. The method is based on the construction of an effective Hamiltonian enabling one to describe the dynamics of the translation degree of freedom of moving breathers. Error estimate on the approximate dynamics is also studied. The concept of the Peierls-Nabarro barrier can be made clear in this framework. We illustrate the method with two simple examples, namely the Salerno model which interpolates between the Ablowitz-Ladik lattice and the discrete nonlinear Schrödinger system, and the Fermi-Pasta-Ulam chain.

[Neural control of somatic muscle function in the earthworm, Allobophora longa, and in the leech, Hirudo medicinalis].

PubMed

David, O F

1978-01-01

Studies have been made on the electrical activity of the segmentary nerves and connectives of the abdominal nervous chain in the earthworm and leech. It was shown that the electrical activity of the isolated piece of the abdominal chain of the leech is manifested of periodic outbursts of impulsation. Presumably this central periodicity accounts for the discharge-like pattern of muscle rhythmic activity which was revealed in our earlier investigations. The electrical activity in the central nervous system of the earthworm depends on afferent influences which pass to the ganglia from the peripheral sensory nervous cells. Stimulation of the abdominal nervous chain did not result in extra discharges of muscle activity, but only affected some of the parameters of the latter.

Structure of the exotic He 9 nucleus from the no-core shell model with continuum

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

Vorabbi, Matteo; Calci, Angelo; Navratil, Petr

2018-03-13

Here, the exotic 9He nucleus, which presents one of the most extreme neutron-to-proton ratios, belongs to the N = 7 isotonic chain famous for the phenomenon of ground-state parity inversion with decreasing number of protons. Consequently, it would be expected to have an unnatural (positive) parity ground state similar to 11Be and 10Li. Despite many experimental and theoretical investigations, its structure remains uncertain. Apart from the fact that it is unbound, other properties including the spin and parity of its ground state, and the very existence of additional low-lying resonances are still a matter of debate

A New One-dimensional Quantum Material - Ta2Pd3Se8 Atomic Chain

NASA Astrophysics Data System (ADS)

Liu, Xue; Liu, Jinyu; Hu, Jin; Yue, Chunlei; Mao, Zhiqiang; Wei, Jiang; Antipina, Liubov; Sorokin, Pavel; Sanchez, Ana

Since the discovery of carbon nanotube, there has been a persistent effort to search for other one dimensional (1D) quantum systems. However, only a few examples have been found. We report a new 1D example - semiconducting Ta2Pd3Se8. We demonstrate that the Ta2Pd3Se8 nanowire as thin as 1.3nm can be easily obtained by applying simple mechanical exfoliation from its bulk counterpart. High resolution TEM shows an intrinsic 1D chain-like crystalline morphology on these nano wires, indicating weak bonding between these atomic chains. Theoretical calculation shows a direct bandgap structure, which evolves from 0.53eV in the bulk to 1.04eV in single atomic chain. The field effect transistor based on Ta2Pd3Se8 nanowire achieved a promising performance with 104On/Off ratio and 80 cm2V-1s-1 mobility. Low temperature transport study reflects two different mechanisms, variable range hopping and thermal activation, which dominate the transport properties at different temperature regimes. Ta2Pd3Se8 nanowire provides an intrinsic 1D material system for the study low dimensional condensed matter physics.

Atomic spin-chain realization of a model for quantum criticality

NASA Astrophysics Data System (ADS)

Toskovic, R.; van den Berg, R.; Spinelli, A.; Eliens, I. S.; van den Toorn, B.; Bryant, B.; Caux, J.-S.; Otte, A. F.

2016-07-01

The ability to manipulate single atoms has opened up the door to constructing interesting and useful quantum structures from the ground up. On the one hand, nanoscale arrangements of magnetic atoms are at the heart of future quantum computing and spintronic devices; on the other hand, they can be used as fundamental building blocks for the realization of textbook many-body quantum models, illustrating key concepts such as quantum phase transitions, topological order or frustration as a function of system size. Here, we use low-temperature scanning tunnelling microscopy to construct arrays of magnetic atoms on a surface, designed to behave like spin-1/2 XXZ Heisenberg chains in a transverse field, for which a quantum phase transition from an antiferromagnetic to a paramagnetic phase is predicted in the thermodynamic limit. Site-resolved measurements on these finite-size realizations reveal a number of sudden ground state changes when the field approaches the critical value, each corresponding to a new domain wall entering the chains. We observe that these state crossings become closer for longer chains, suggesting the onset of critical behaviour. Our results present opportunities for further studies on quantum behaviour of many-body systems, as a function of their size and structural complexity.

Uncertainty Quantification in Climate Modeling and Projection

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

Qian, Yun; Jackson, Charles; Giorgi, Filippo

The projection of future climate is one of the most complex problems undertaken by the scientific community. Although scientists have been striving to better understand the physical basis of the climate system and to improve climate models, the overall uncertainty in projections of future climate has not been significantly reduced (e.g., from the IPCC AR4 to AR5). With the rapid increase of complexity in Earth system models, reducing uncertainties in climate projections becomes extremely challenging. Since uncertainties always exist in climate models, interpreting the strengths and limitations of future climate projections is key to evaluating risks, and climate change informationmore » for use in Vulnerability, Impact, and Adaptation (VIA) studies should be provided with both well-characterized and well-quantified uncertainty. The workshop aimed at providing participants, many of them from developing countries, information on strategies to quantify the uncertainty in climate model projections and assess the reliability of climate change information for decision-making. The program included a mixture of lectures on fundamental concepts in Bayesian inference and sampling, applications, and hands-on computer laboratory exercises employing software packages for Bayesian inference, Markov Chain Monte Carlo methods, and global sensitivity analyses. The lectures covered a range of scientific issues underlying the evaluation of uncertainties in climate projections, such as the effects of uncertain initial and boundary conditions, uncertain physics, and limitations of observational records. Progress in quantitatively estimating uncertainties in hydrologic, land surface, and atmospheric models at both regional and global scales was also reviewed. The application of Uncertainty Quantification (UQ) concepts to coupled climate system models is still in its infancy. The Coupled Model Intercomparison Project (CMIP) multi-model ensemble currently represents the primary data for assessing reliability and uncertainties of climate change information. An alternative approach is to generate similar ensembles by perturbing parameters within a single-model framework. One of workshop’s objectives was to give participants a deeper understanding of these approaches within a Bayesian statistical framework. However, there remain significant challenges still to be resolved before UQ can be applied in a convincing way to climate models and their projections.« less

Cutaneous lymphomatoid granulomatosis: correlation of clinical and biologic features.

PubMed

Beaty, M W; Toro, J; Sorbara, L; Stern, J B; Pittaluga, S; Raffeld, M; Wilson, W H; Jaffe, E S

2001-09-01

Lymphomatoid granulomatosis (LYG) is a rare angiocentric and angiodestructive Epstein-Barr virus-associated B-cell lymphoproliferative disorder (EBV-BLPD), varying widely from an indolent process to an aggressive large cell lymphoma. The skin is the extrapulmonary organ most commonly involved in LYG. We studied 32 skin lesions from 20 patients with known pulmonary LYG, using immunohistochemistry, in situ hybridization for EBV, and polymerase chain reaction for the presence of antigen receptor gene rearrangements (IgH and TCR) to better define both the clinicopathologic spectrum and pathogenesis of the cutaneous lesions. We describe two distinct patterns of cutaneous involvement. Multiple erythematous dermal papules and/or subcutaneous nodules, with or without ulceration, were present in 17 patients (85%). These lesions demonstrate a marked angiocentric lymphohistiocytic infiltrate, composed predominantly of CD4-positive T-cells, with a high propensity for involving the subcutaneous tissues, and exhibiting angiodestruction, necrosis, and cytologic atypia. EBV-positive B-cells were detected in the nodules from five patients; clonal immunoglobulin heavy chain gene (IgH) rearrangements were detected by polymerase chain reaction in two patients. Multiple indurated, erythematous to white plaques were present in three patients (15%). The plaque lesions were negative for EBV and clonal IgH gene rearrangements in all cases studied. The clinical course of overall disease was variable, ranging from spontaneous regression without treatment (1 of 13; 7%), resolution with chemo/immunomodulatory therapy (8 of 13; 62%), and progression (4 of 13; 31%). The clinical and histopathologic features of cutaneous LYG are extremely diverse. However, the majority (85%) of the cutaneous lesions mirrors to some extent LYG in the lung, although EBV+ cells are less frequently identified. This subset of cases shows the histopathologic triad of angiodestruction with associated necrosis, panniculitis, and in some cases atypical lymphoid cells. The commonality of the histologic features in this group suggests a common pathophysiologic basis, possibly mediated by cytokines and chemokines induced by EBV. A small percentage of the lesions (15%) presented as indurated and atrophic plaques, and EBV was not identified in the small number of cases studied. The relationship of the plaque-like lesions to LYG remains uncertain. Whereas some cases of LYG regress spontaneously, most require therapy.

Using multiobjective tradeoff sets and Multivariate Regression Trees to identify critical and robust decisions for long term water utility planning

NASA Astrophysics Data System (ADS)

Smith, R.; Kasprzyk, J. R.; Balaji, R.

2017-12-01

In light of deeply uncertain factors like future climate change and population shifts, responsible resource management will require new types of information and strategies. For water utilities, this entails potential expansion and efficient management of water supply infrastructure systems for changes in overall supply; changes in frequency and severity of climate extremes such as droughts and floods; and variable demands, all while accounting for conflicting long and short term performance objectives. Multiobjective Evolutionary Algorithms (MOEAs) are emerging decision support tools that have been used by researchers and, more recently, water utilities to efficiently generate and evaluate thousands of planning portfolios. The tradeoffs between conflicting objectives are explored in an automated way to produce (often large) suites of portfolios that strike different balances of performance. Once generated, the sets of optimized portfolios are used to support relatively subjective assertions of priorities and human reasoning, leading to adoption of a plan. These large tradeoff sets contain information about complex relationships between decisions and between groups of decisions and performance that, until now, has not been quantitatively described. We present a novel use of Multivariate Regression Trees (MRTs) to analyze tradeoff sets to reveal these relationships and critical decisions. Additionally, when MRTs are applied to tradeoff sets developed for different realizations of an uncertain future, they can identify decisions that are robust across a wide range of conditions and produce fundamental insights about the system being optimized.

Quantifying Supply Risk at a Cellulosic Biorefinery

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

Hansen, Jason K; Jacobson, Jacob Jordan; Cafferty, Kara Grace

In order to increase the sustainability and security of the nation’s energy supply, the U.S. Department of Energy through its Bioenergy Technology Office has set a vision for one billion tons of biomass to be processed for renewable energy and bioproducts annually by the year 2030. The Renewable Fuels Standard limits the amount of corn grain that can be used in ethanol conversion sold in the U.S, which is already at its maximum. Therefore making the DOE’s vision a reality requires significant growth in the advanced biofuels industry where currently three cellulosic biorefineries convert cellulosic biomass to ethanol. Risk mitigationmore » is central to growing the industry beyond its infancy to a level necessary to achieve the DOE vision. This paper focuses on reducing the supply risk that faces a firm that owns a cellulosic biorefinery. It uses risk theory and simulation modeling to build a risk assessment model based on causal relationships of underlying, uncertain, supply driving variables. Using the model the paper quantifies supply risk reduction achieved by converting the supply chain from a conventional supply system (bales and trucks) to an advanced supply system (depots, pellets, and trains). Results imply that the advanced supply system reduces supply system risk, defined as the probability of a unit cost overrun, from 83% in the conventional system to 4% in the advanced system. Reducing cost risk in this nascent industry improves the odds of realizing desired growth.« less

Four Japanese male patients with juvenile retinoschisis: only three have mutations in the RS1 gene.

PubMed

Hayashi, Takaaki; Omoto, Satoshi; Takeuchi, Tomokazu; Kozaki, Kenichi; Ueoka, Yasuo; Kitahara, Kenji

2004-11-01

To describe the clinical phenotypes of four unrelated Japanese male patients with juvenile retinoschisis and to investigate occurrences of mutations in the RS1 gene. Observational case series and experimental study. Fundus examinations, fluorescein angiography, and single-flash electroretinography (ERG) were carried out. In one patient, optical coherence tomography (OCT) was performed. The coding regions of the RS1 gene that encodes retinoschisin were amplified by polymerase chain reaction (PCR). The PCR products were purified and directly sequenced. The four affected patients showed cystoid- or wheel-like foveal changes with a little or no fluorescein leakage and negative b-wave patterns in both eyes. The OCT images of foveal retinoschisis disclosed that splitting occurs in the putative fibers of Henle. In three patients, we identified three different missense mutations (p.S73P, p.Y89C, p.R209C) in the functionally important discoidin domain of the RS1 gene. The p.S73P mutation has not been previously reported. In contrast, no nucleotide substitutions were detected in the fourth patient whose parents were unrelated and asymptomatic. No other member of this family for three generations has had juvenile retinoschisis. Because serine 73 is conserved in the mouse ortholog and other discoidin proteins, the proline 73 allele is therefore very likely to encode a defective retinoschisin. Although the inheritance pattern is uncertain in the patient without the RS1 mutation, the clinical and ERG findings were indistinguishable from those of patients with RS1 mutations. This finding points to the genetic heterogeneity of juvenile retinoschisis.

A Study of The Effect of Demand Uncertainty for Low-Carbon Products Using a Newsvendor Model

PubMed Central

Qu, Shaojian; Zhou, Yongyi

2017-01-01

This paper studies the effect of uncertain demand on a low-carbon product by using a newsvendor model. With two different kinds of market scales, we examine a game whereby a manufacturer produces and delivers a single new low-carbon product to a single retailer. The retailer observes the demand information and gives an order before the selling season. We find in the game that if the retailer shares truthful (or in contrast unreal or even does not share) forecast information with the manufacturer, the manufacturer will give a low (high) wholesale price through the sequence of events. In addition, as a policy-maker, the government posts a subsidy by selling the low-carbon product per unit. The manufacturer creates a new contract with a rebate for the retailer. We also take the consumer aversion coefficient and truth coefficient as qualitative variables into our model to study the order, pricing, and expected profit for the members of supply chain. The research shows that uncertain demand causes a the major effect on the new low-carbon product. Thereby, we suggest the retailer should share more truthful information with the manufacturer. PMID:29068382

A Study of The Effect of Demand Uncertainty for Low-Carbon Products Using a Newsvendor Model.

PubMed

Qu, Shaojian; Zhou, Yongyi

2017-10-25

This paper studies the effect of uncertain demand on a low-carbon product by using a newsvendor model. With two different kinds of market scales, we examine a game whereby a manufacturer produces and delivers a single new low-carbon product to a single retailer. The retailer observes the demand information and gives an order before the selling season. We find in the game that if the retailer shares truthful (or in contrast unreal or even does not share) forecast information with the manufacturer, the manufacturer will give a low (high) wholesale price through the sequence of events. In addition, as a policy-maker, the government posts a subsidy by selling the low-carbon product per unit. The manufacturer creates a new contract with a rebate for the retailer. We also take the consumer aversion coefficient and truth coefficient as qualitative variables into our model to study the order, pricing, and expected profit for the members of supply chain. The research shows that uncertain demand causes a the major effect on the new low-carbon product. Thereby, we suggest the retailer should share more truthful information with the manufacturer.

Estimation in Linear Systems Featuring Correlated Uncertain Observations Coming from Multiple Sensors

NASA Astrophysics Data System (ADS)

Caballero-Águila, R.; Hermoso-Carazo, A.; Linares-Pérez, J.

2009-08-01

In this paper, the state least-squares linear estimation problem from correlated uncertain observations coming from multiple sensors is addressed. It is assumed that, at each sensor, the state is measured in the presence of additive white noise and that the uncertainty in the observations is characterized by a set of Bernoulli random variables which are only correlated at consecutive time instants. Assuming that the statistical properties of such variables are not necessarily the same for all the sensors, a recursive filtering algorithm is proposed, and the performance of the estimators is illustrated by a numerical simulation example wherein a signal is estimated from correlated uncertain observations coming from two sensors with different uncertainty characteristics.

Vibrational soliton: an experimental overview

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

Bigio, I.J.

1986-03-08

To date the most convincing evidence of vibrational solitons in biopolymers has been found in two very disparate systems: Davydov-like excitations in hydrogen-bonded linear chains (acetanilide and N-methylacetamide) which are not biopolymers but plausible structural paradigms for biopolymers, and longitudinal accoustic modes of possibly nonlinear character in biologically viable DNA. 17 refs., 4 figs.

Loschmidt echo as a robust decoherence quantifier for many-body systems

NASA Astrophysics Data System (ADS)

Zangara, Pablo R.; Dente, Axel D.; Levstein, Patricia R.; Pastawski, Horacio M.

2012-07-01

We employ the Loschmidt echo, i.e., the signal recovered after the reversal of an evolution, to identify and quantify the processes contributing to decoherence. This procedure, which has been extensively used in single-particle physics, is employed here in a spin ladder. The isolated chains have 1/2 spins with XY interaction and their excitations would sustain a one-body-like propagation. One of them constitutes the controlled system S whose reversible dynamics is degraded by the weak coupling with the uncontrolled second chain, i.e., the environment E. The perturbative SE coupling is swept through arbitrary combinations of XY and Ising-like interactions, that contain the standard Heisenberg and dipolar ones. Different time regimes are identified for the Loschmidt echo dynamics in this perturbative configuration. In particular, the exponential decay scales as a Fermi golden rule, where the contributions of the different SE terms are individually evaluated and analyzed. Comparisons with previous analytical and numerical evaluations of decoherence based on the attenuation of specific interferences show that the Loschmidt echo is an advantageous decoherence quantifier at any time, regardless of the S internal dynamics.

Stability analysis of fuzzy parametric uncertain systems.

PubMed

Bhiwani, R J; Patre, B M

2011-10-01

In this paper, the determination of stability margin, gain and phase margin aspects of fuzzy parametric uncertain systems are dealt. The stability analysis of uncertain linear systems with coefficients described by fuzzy functions is studied. A complexity reduced technique for determining the stability margin for FPUS is proposed. The method suggested is dependent on the order of the characteristic polynomial. In order to find the stability margin of interval polynomials of order less than 5, it is not always necessary to determine and check all four Kharitonov's polynomials. It has been shown that, for determining stability margin of FPUS of order five, four, and three we require only 3, 2, and 1 Kharitonov's polynomials respectively. Only for sixth and higher order polynomials, a complete set of Kharitonov's polynomials are needed to determine the stability margin. Thus for lower order systems, the calculations are reduced to a large extent. This idea has been extended to determine the stability margin of fuzzy interval polynomials. It is also shown that the gain and phase margin of FPUS can be determined analytically without using graphical techniques. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Chaos Suppression in Fractional order Permanent Magnet Synchronous Generator in Wind Turbine Systems

NASA Astrophysics Data System (ADS)

Rajagopal, Karthikeyan; Karthikeyan, Anitha; Duraisamy, Prakash

2017-06-01

In this paper we investigate the control of three-dimensional non-autonomous fractional-order uncertain model of a permanent magnet synchronous generator (PMSG) via a adaptive control technique. We derive a dimensionless fractional order model of the PMSM from the integer order presented in the literatures. Various dynamic properties of the fractional order model like eigen values, Lyapunov exponents, bifurcation and bicoherence are investigated. The system chaotic behavior for various orders of fractional calculus are presented. An adaptive controller is derived to suppress the chaotic oscillations of the fractional order model. As the direct Lyapunov stability analysis of the robust controller is difficult for a fractional order first derivative, we have derived a new lemma to analyze the stability of the system. Numerical simulations of the proposed chaos suppression methodology are given to prove the analytical results derived through which we show that for the derived adaptive controller and the parameter update law, the origin of the system for any bounded initial conditions is asymptotically stable.

Self-Assemblies of novel molecules, VECAR

NASA Astrophysics Data System (ADS)

Shrestha, Bijay; Kim, Hye-Young; Lee, Soojin; Novak, Brian; Moldovan, Dorel

2015-03-01

VECAR is a newly synthesized molecule, which is an amphiphilic antioxidant molecule that consists of two molecular groups, vitamin-E and Carnosine, linked by a hydrocarbon chain. The hydrocarbon chain is hydrophobic and both vitamin-E and Carnosine ends are hydrophilic. In the synthesis process, the length of the hydrophobic chain of VECAR molecules can vary from the shortest (n =0) to the longest (n =18), where n indicates the number of carbon atoms in the chain. We conducted MD simulation studies of self-assembly of VECAR molecules in water using GROMACS on LONI HPC resources. Our study shows that there is a strong correlation between the shape and atomistic structure of the self-assembled nano-structures (SANs) and the chain-length (n) of VECAR molecules. We will report the results of data analyses including the atomistic structure of each SANs and the dynamic and energetic mechanisms of their formation as function of time. In summary, both VECAR molecules of chain-length n =18 and 9 form worm-like micelles, which may be used as a drug delivery system. This research is supported by the Louisiana Board of Regents-RCS Grant (LEQSF(2012-15)-RD-A-19).

Eyetracking Reveals Multiple-Category Use in Induction

ERIC Educational Resources Information Center

Chen, Stephanie Y.; Ross, Brian H.; Murphy, Gregory L.

2016-01-01

Category information is used to predict properties of new category members. When categorization is uncertain, people often rely on only one, most likely category to make predictions. Yet studies of perception and action often conclude that people combine multiple sources of information near-optimally. We present a perception-action analog of…

Teach Like a Human: The Reality Gap in Educator Preparation

ERIC Educational Resources Information Center

Hirsch, Miriam

2016-01-01

This reflective essay examines educator preparation through the lens of Paul Kalanithi's poignant memoir "When Breath Becomes Air." Based on her work with preservice teacher candidates, the author questions the meaning of teacher preparation in our uncertain educational landscape. Drawing on the lessons of Maxine Greene and John Dewey…

Innovation: Tougher than It Looks

ERIC Educational Resources Information Center

Sparks, Sarah D.

2011-01-01

Massive federal education competitions like the $650 million Investing in Innovation fund have heightened interest in practical education research, but even the most promising findings aimed at improving student learning face a long, uncertain path to become something more concrete and usable for the classroom. Unlike fields such as physics or…

Electrochemical method of controlling thiolate coverage on a conductive substrate such as gold

NASA Technical Reports Server (NTRS)

Porter, Marc D. (Inventor); Weisshaar, Duane E. (Inventor)

1998-01-01

An electrochemical method for forming a partial monomolecular layer of a predetermined extent of coverage of a thiolate of the formula, XRS--, therein R can be a linear or branched chain hydrocarbon or an aromatic or the like and X can be any compatible end group, e.g., OH, COOH, CH.sub.3 or the like, upon a substrate such as gold, which involves applying in an electrochemical system a constant voltage preselected to yield the desired predetermined extent of coverage.

Electrochemical method of controlling thiolate coverage on a conductive substrate such as gold

DOEpatents

Porter, Marc D.; Weisshaar, Duane E.

1998-10-27

An electrochemical method for forming a partial monomolecular layer of a predetermined extent of coverage of a thiolate of the formula, XRS--, therein R can be a linear or branched chain hydrocarbon or an aromatic or the like and X can be any compatible end group, e.g., OH, COOH, CH.sub.3 or the like, upon a substrate such as gold, which involves applying in an electrochemical system a constant voltage preselected to yield the desired predetermined extent of coverage.

Electrochemical method of controlling thiolate coverage on a conductive substrate such as gold

DOEpatents

Porter, Marc D.; Weisshaar, Duane E.

1997-06-03

An electrochemical method for forming a partial monomolecular layer of a predetermined extent of coverage of a thiolate of the formula, XRS.sup.-, wherein R can be a linear or branched chain hydrocarbon or an aromatic or the like and X can be any compatible end group, e.g., OH, COOH, CH.sub.3 or the like, upon a substrate such as gold, which involves applying in an electrochemical system a constant voltage preselected to yield the desired predetermined extent of coverage.

The commercial performance of cellulosic ethanol supply-chains in Europe

PubMed Central

Slade, Raphael; Bauen, Ausilio; Shah, Nilay

2009-01-01

Background The production of fuel-grade ethanol from lignocellulosic biomass resources has the potential to increase biofuel production capacity whilst minimising the negative environmental impacts. These benefits will only be realised if lignocellulosic ethanol production can compete on price with conventional fossil fuels and if it can be produced commercially at scale. This paper focuses on lignocellulosic ethanol production in Europe. The hypothesis is that the eventual cost of production will be determined not only by the performance of the conversion process but by the performance of the entire supply-chain from feedstock production to consumption. To test this, a model for supply-chain cost comparison is developed, the components of representative ethanol supply-chains are described, the factors that are most important in determining the cost and profitability of ethanol production are identified, and a detailed sensitivity analysis is conducted. Results The most important cost determinants are the cost of feedstocks, primarily determined by location and existing markets, and the value obtained for ethanol, primarily determined by the oil price and policy incentives. Both of these factors are highly uncertain. The best performing chains (ethanol produced from softwood and sold as a low percentage blend with gasoline) could ultimately be cost competitive with gasoline without requiring subsidy, but production from straw would generally be less competitive. Conclusion Supply-chain design will play a critical role in determining commercial viability. The importance of feedstock supply highlights the need for location-specific assessments of feedstock availability and price. Similarly, the role of subsidies and policy incentives in creating and sustaining the ethanol market highlights the importance of political engagement and the need to include political risks in investment appraisal. For the supply-chains described here, and with the cost and market parameters selected, selling ethanol as a low percentage blend with gasoline will maximise ethanol revenues and minimise the need for subsidies. It follows, therefore, that the market for low percentage blends should be saturated before markets for high percentage blends. PMID:19192294

A robust H∞-tracking design for uncertain Takagi-Sugeno fuzzy systems with unknown premise variables using descriptor redundancy approach

NASA Astrophysics Data System (ADS)

Hassan Asemani, Mohammad; Johari Majd, Vahid

2015-12-01

This paper addresses a robust H∞ fuzzy observer-based tracking design problem for uncertain Takagi-Sugeno fuzzy systems with external disturbances. To have a practical observer-based controller, the premise variables of the system are assumed to be not measurable in general, which leads to a more complex design process. The tracker is synthesised based on a fuzzy Lyapunov function approach and non-parallel distributed compensation (non-PDC) scheme. Using the descriptor redundancy approach, the robust stability conditions are derived in the form of strict linear matrix inequalities (LMIs) even in the presence of uncertainties in the system, input, and output matrices simultaneously. Numerical simulations are provided to show the effectiveness of the proposed method.

Finite-time master-slave synchronization and parameter identification for uncertain Lurie systems.

PubMed

Wang, Tianbo; Zhao, Shouwei; Zhou, Wuneng; Yu, Weiqin

2014-07-01

This paper investigates the finite-time master-slave synchronization and parameter identification problem for uncertain Lurie systems based on the finite-time stability theory and the adaptive control method. The finite-time master-slave synchronization means that the state of a slave system follows with that of a master system in finite time, which is more reasonable than the asymptotical synchronization in applications. The uncertainties include the unknown parameters and noise disturbances. An adaptive controller and update laws which ensures the synchronization and parameter identification to be realized in finite time are constructed. Finally, two numerical examples are given to show the effectiveness of the proposed method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Robust Control of Uncertain Systems via Dissipative LQG-Type Controllers

NASA Technical Reports Server (NTRS)

Joshi, Suresh M.

2000-01-01

Optimal controller design is addressed for a class of linear, time-invariant systems which are dissipative with respect to a quadratic power function. The system matrices are assumed to be affine functions of uncertain parameters confined to a convex polytopic region in the parameter space. For such systems, a method is developed for designing a controller which is dissipative with respect to a given power function, and is simultaneously optimal in the linear-quadratic-Gaussian (LQG) sense. The resulting controller provides robust stability as well as optimal performance. Three important special cases, namely, passive, norm-bounded, and sector-bounded controllers, which are also LQG-optimal, are presented. The results give new methods for robust controller design in the presence of parametric uncertainties.

Adaptive output-feedback control for switched stochastic uncertain nonlinear systems with time-varying delay.

PubMed

Song, Zhibao; Zhai, Junyong

2018-04-01

This paper addresses the problem of adaptive output-feedback control for a class of switched stochastic time-delay nonlinear systems with uncertain output function, where both the control coefficients and time-varying delay are unknown. The drift and diffusion terms are subject to unknown homogeneous growth condition. By virtue of adding a power integrator technique, an adaptive output-feedback controller is designed to render that the closed-loop system is bounded in probability, and the state of switched stochastic nonlinear system can be globally regulated to the origin almost surely. A numerical example is provided to demonstrate the validity of the proposed control method. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

The Absolute Stability Analysis in Fuzzy Control Systems with Parametric Uncertainties and Reference Inputs

NASA Astrophysics Data System (ADS)

Wu, Bing-Fei; Ma, Li-Shan; Perng, Jau-Woei

This study analyzes the absolute stability in P and PD type fuzzy logic control systems with both certain and uncertain linear plants. Stability analysis includes the reference input, actuator gain and interval plant parameters. For certain linear plants, the stability (i.e. the stable equilibriums of error) in P and PD types is analyzed with the Popov or linearization methods under various reference inputs and actuator gains. The steady state errors of fuzzy control systems are also addressed in the parameter plane. The parametric robust Popov criterion for parametric absolute stability based on Lur'e systems is also applied to the stability analysis of P type fuzzy control systems with uncertain plants. The PD type fuzzy logic controller in our approach is a single-input fuzzy logic controller and is transformed into the P type for analysis. In our work, the absolute stability analysis of fuzzy control systems is given with respect to a non-zero reference input and an uncertain linear plant with the parametric robust Popov criterion unlike previous works. Moreover, a fuzzy current controlled RC circuit is designed with PSPICE models. Both numerical and PSPICE simulations are provided to verify the analytical results. Furthermore, the oscillation mechanism in fuzzy control systems is specified with various equilibrium points of view in the simulation example. Finally, the comparisons are also given to show the effectiveness of the analysis method.

Plan Debugging Using Approximate Domain Theories.

DTIC Science & Technology

1995-03-01

compelling suggestion that generative plan- ning systems solving large problems will need to exploit the control information implicit in uncertain...control information implicit in uncertain information may well lead the planner to expand one portion of a plan at one point, and a separate portion of...solutions that have been proposed are to abandon declarativism (as suggested in the work on situated automata theory and its variants [1, 16, 56, 72

Systemic lupus erythematosus: molecular cloning and analysis of 22 individual recombinant monoclonal kappa light chains specifically hydrolyzing human myelin basic protein.

PubMed

Timofeeva, Anna M; Buneva, Valentina N; Nevinsky, Georgy A

2015-10-01

Antibodies hydrolyzing myelin basic protein (MBP) can play an important role in the pathogenesis of multiple sclerosis (MS) and systemic lupus erythematosus (SLE). An immunoglobulin light chain phagemid library derived from peripheral blood lymphocytes of patients with SLE was used. Small pools of phage particles displaying light chains with different affinities for MBP were isolated by affinity chromatography on MBP-Sepharose, and the fraction eluted with 0.5 M NaCl was used for preparation of individual monoclonal light chains (MLChs, 26-27 kDa). Seventy-two of 440 individual colonies were randomly chosen, expressed in Escherichia coli in a soluble form, and MLChs were purified by metal chelating chromatography. Twenty-two of 72 MLChs have high affinity and efficiently hydrolyze only MBP (not other control proteins) demonstrating various pH optima in a 5.7-9.0 range and different substrate specificity in the hydrolysis of four different MBP oligopeptides. Four MLChs demonstrated serine protease-like and three thiol protease-like activities, while 11 MLChs were metalloproteases. The activity of three MLChs was inhibited by both phenylmethylsulfonyl fluoride (PMSF) and Ethylenediaminetetraacetic acid (EDTA), two other by EDTA and iodoacetamide, and one by PMSF, EDTA, and iodoacetamide. The ratio of relative activity in the presence of Ca(2+), Mg(2+), Mn(2+), Ni(2+), Zn(2+), Cu(2+), and Co(2+) was individual for each of 22 MLCh preparations. It is the first examples of human MLChs, which probably can possess two or even three different proteolytic activities. These observations suggest an extreme diversity of anti-MBP abzymes in SLE patients. The immune systems of individual SLE patients can generate a variety of anti-MBP abzymes, which can attack MBP of myelin-proteolipid sheath of axons and play an important role in MS and SLE pathogenesis. Copyright © 2015 John Wiley & Sons, Ltd.

Two-stage ordering processes under annealing of Sr submonolayers on Mo(1 1 2)

NASA Astrophysics Data System (ADS)

Fedorus, A.; Godzik, G.; Naumovets, A.; Pfnür, H.

2004-09-01

Using LEED as technique of investigation, the evolution of geometrical order in the system Sr/Mo(1 1 2) was studied after annealing at temperatures between 100 and 900 K. Two stages of ordering were found for the chain-like structures p(8 × 1) and p(5 × 1). Partial ordering occurred already at the base adsorption temperature (90 K) with slight improvement after annealing to temperatures around 200 K. The full equilibration of the layers, however, was found to happen only at high annealing temperatures (ranging between 500 and 600 K, depending on coverage). Correlating these data with the highly anisotropic diffusivity known for Sr overlayers on Mo(1 1 2), we assume that the low-temperature ordering sets in via a kink-like diffusion of adsorbate chains essentially along the substrate troughs, whereas in the high-temperature step, diffusion across the troughs is most important.

Organization and hierarchy of the human functional brain network lead to a chain-like core.

PubMed

Mastrandrea, Rossana; Gabrielli, Andrea; Piras, Fabrizio; Spalletta, Gianfranco; Caldarelli, Guido; Gili, Tommaso

2017-07-07

The brain is a paradigmatic example of a complex system: its functionality emerges as a global property of local mesoscopic and microscopic interactions. Complex network theory allows to elicit the functional architecture of the brain in terms of links (correlations) between nodes (grey matter regions) and to extract information out of the noise. Here we present the analysis of functional magnetic resonance imaging data from forty healthy humans at rest for the investigation of the basal scaffold of the functional brain network organization. We show how brain regions tend to coordinate by forming a highly hierarchical chain-like structure of homogeneously clustered anatomical areas. A maximum spanning tree approach revealed the centrality of the occipital cortex and the peculiar aggregation of cerebellar regions to form a closed core. We also report the hierarchy of network segregation and the level of clusters integration as a function of the connectivity strength between brain regions.

An optimized formulation of a thermostable spray dried virus-like particles vaccine against human papillomavirus

PubMed Central

Saboo, Sugandha; Tumban, Ebenezer; Peabody, Julianne; Wafula, Denis; Peabody, David S.; Chackerian, Bryce; Muttil, Pavan

2016-01-01

Existing vaccines against human papillomavirus (HPV) require continuous cold-chain storage. Previously, we developed a bacteriophage virus-like particle (VLP) based vaccine for Human Papillomavirus (HPV) infection, which elicits broadly neutralizing antibodies against diverse HPV types. Here, we formulated these VLPs into a thermostable dry powder using a multi-component excipient system and by optimizing the spray drying parameters using a half-factorial design approach. Dry powder VLPs were stable after spray drying and after long-term storage at elevated temperatures. Immunization of mice with a single dose of reconstituted dry powder VLPs that were stored at 37°C for more than a year elicited high anti-L2 IgG antibody titers. Spray dried thermostable, broadly protective L2 bacteriophage VLPs vaccine could be accessible to remote regions of the world (where ~84% of cervical cancer patients reside) by eliminating the cold-chain requirement during transportation and storage. PMID:27019231

Treatment of Invasive Brain Tumors Using a Chain-like Nanoparticle.

PubMed

Peiris, Pubudu M; Abramowski, Aaron; Mcginnity, James; Doolittle, Elizabeth; Toy, Randall; Gopalakrishnan, Ramamurthy; Shah, Shruti; Bauer, Lisa; Ghaghada, Ketan B; Hoimes, Christopher; Brady-Kalnay, Susann M; Basilion, James P; Griswold, Mark A; Karathanasis, Efstathios

2015-04-01

Glioblastoma multiforme is generally recalcitrant to current surgical and local radiotherapeutic approaches. Moreover, systemic chemotherapeutic approaches are impeded by the blood-tumor barrier. To circumvent limitations in the latter area, we developed a multicomponent, chain-like nanoparticle that can penetrate brain tumors, composed of three iron oxide nanospheres and one drug-loaded liposome linked chemically into a linear chain-like assembly. Unlike traditional small-molecule drugs or spherical nanotherapeutics, this oblong-shaped, flexible nanochain particle possessed a unique ability to gain access to and accumulate at glioma sites. Vascular targeting of nanochains to the αvβ3 integrin receptor resulted in a 18.6-fold greater drug dose administered to brain tumors than standard chemotherapy. By 2 hours after injection, when nanochains had exited the blood stream and docked at vascular beds in the brain, the application of an external low-power radiofrequency field was sufficient to remotely trigger rapid drug release. This effect was produced by mechanically induced defects in the liposomal membrane caused by the oscillation of the iron oxide portion of the nanochain. In vivo efficacy studies conducted in two different mouse orthotopic models of glioblastoma illustrated how enhanced targeting by the nanochain facilitates widespread site-specific drug delivery. Our findings offer preclinical proof-of-concept for a broadly improved method for glioblastoma treatment. ©2015 American Association for Cancer Research.

Robust adaptive uniform exact tracking control for uncertain Euler-Lagrange system

NASA Astrophysics Data System (ADS)

Yang, Yana; Hua, Changchun; Li, Junpeng; Guan, Xinping

2017-12-01

This paper offers a solution to the robust adaptive uniform exact tracking control for uncertain nonlinear Euler-Lagrange (EL) system. An adaptive finite-time tracking control algorithm is designed by proposing a novel nonsingular integral terminal sliding-mode surface. Moreover, a new adaptive parameter tuning law is also developed by making good use of the system tracking errors and the adaptive parameter estimation errors. Thus, both the trajectory tracking and the parameter estimation can be achieved in a guaranteed time adjusted arbitrarily based on practical demands, simultaneously. Additionally, the control result for the EL system proposed in this paper can be extended to high-order nonlinear systems easily. Finally, a test-bed 2-DOF robot arm is set-up to demonstrate the performance of the new control algorithm.

Big angiotensin-25: a novel glycosylated angiotensin-related peptide isolated from human urine.

PubMed

Nagata, Sayaka; Hatakeyama, Kinta; Asami, Maki; Tokashiki, Mariko; Hibino, Hajime; Nishiuchi, Yuji; Kuwasako, Kenji; Kato, Johji; Asada, Yujiro; Kitamura, Kazuo

2013-11-29

The renin-angiotensin system (RAS), including angiotensin II (Ang II), plays an important role in the regulation of blood pressure and body fluid balance. Consequently, the RAS has emerged as a key target for treatment of kidney and cardiovascular disease. In a search for bioactive peptides using an antibody against the N-terminal portion of Ang II, we identified and characterized a novel angiotensin-related peptide from human urine as a major molecular form. We named the peptide Big angiotensin-25 (Bang-25) because it consists of 25 amino acids with a glycosyl chain and added cysteine. Bang-25 is rapidly cleaved by chymase to Ang II, but is resistant to cleavage by renin. The peptide is abundant in human urine and is present in a wide range of organs and tissues. In particular, immunostaining of Bang-25 in the kidney is specifically localized to podocytes. Although the physiological function of Bang-25 remains uncertain, our findings suggest it is processed from angiotensinogen and may represent an alternative, renin-independent path for Ang II synthesis in tissue. Copyright © 2013. Published by Elsevier Inc.

Interactions of long DNA chains with charged surfaces: Entropy, Conformations and Applications

NASA Astrophysics Data System (ADS)

Rondelez, Francis

2004-03-01

The adsorption of long DNA chains on positively charged surfaces is controlled by electrostatics. We demonstrate experimentally on two different systems that the driving force for adsorption is the release of the small counterions surrounding the DNA chains and the charged surface. We then proceed to the study of the conformation of the adsorbed DNA chains. In the first series of experiments, the DNA is in contact with a Langmuir monolayer of cationic amphiphiles. The advantage is that the surface charge density can be varied over a factor of 10 and also that the immobilized DNA chains can be mechanically manipulated. We observe by neutron reflectometry that the chains are essentially flat on the interface, with a few dangling loops. In the second series of experiments the DNA chains are in contact with a solution of cationic polystyrene microspheres. Due to the small size of the particles, the DNA chains adsorb only partially. The fraction of nucleotides localized around the beads can be measured by fluorescence spectroscopy and we compare it to the total number of charges on the particle. We also study the conditions to maximize the wrapping. Such experiments should be useful to better understand the compaction of DNA by histone proteins and formation of nucleosomes. The immobilization of DNA by surfaces also provides a way to control the interactions of DNA with proteins like DNases, exonucleases or RNA polymerases.

Excellent electrochemical performances of cabbage-like polyaniline fabricated by template synthesis

NASA Astrophysics Data System (ADS)

Hu, Chenglong; Chen, Shaoyun; Wang, Yuan; Peng, Xianghong; Zhang, Weihong; Chen, Jian

2016-07-01

In this article, we explore a novel route to fabricate cabbage-like polyaniline (PANI) by in situ polymerization of aniline using the hydroxylated poly (methyl methacrylate) nanospheres (i.e. PMMAsbnd OHsbnd NS) as a template. A maximum specific capacitance of 584 F/g (the current density is 0.1 A/g) is achieved at 10 mV s-1 as well as a high stability of over 3000 cycles (the decrease in the SC is ∼9.1%), which suggests the potential application of the cabbage-like polyaniline in supercapacitors. The predominant electrochemical performances of the cabbage-like polyaniline can be attributed to their large surface area and larger-scale π-π conjugated system present in the quinoid structure of the PANI molecular chain, which can drastically facilitate electron diffusion and improve the utilization of the electroactive PANI during the charge/discharge processes. Accordingly, the facility of charge transfer can decrease resistance along with the PANI molecular chain to improve the electrochemical stability and achieve high-capacitance response characteristics. The present study introduces a new synthesis method for the development of various morphology of other conducting polymer, which may find potential applications in a variety of high-performance electrochemical devices.

Acoustic Type-II Weyl Nodes from Stacking Dimerized Chains

NASA Astrophysics Data System (ADS)

Yang, Zhaoju; Zhang, Baile

2016-11-01

Lorentz-violating type-II Weyl fermions, which were missed in Weyl's prediction of nowadays classified type-I Weyl fermions in quantum field theory, have recently been proposed in condensed matter systems. The semimetals hosting type-II Weyl fermions offer a rare platform for realizing many exotic physical phenomena that are different from type-I Weyl systems. Here we construct the acoustic version of a type-II Weyl Hamiltonian by stacking one-dimensional dimerized chains of acoustic resonators. This acoustic type-II Weyl system exhibits distinct features in a finite density of states and unique transport properties of Fermi-arc-like surface states. In a certain momentum space direction, the velocity of these surface states is determined by the tilting direction of the type-II Weyl nodes rather than the chirality dictated by the Chern number. Our study also provides an approach of constructing acoustic topological phases at different dimensions with the same building blocks.

Cometary Nuclei and Tidal Disruption: The Geologic Record of Crater Chains on Callisto and Ganymede

NASA Technical Reports Server (NTRS)

Schenk, Paul M.; Asphaug, Erik; McKinnon, William B.; Melosh, H. J.; Weissman, Paul R.

1996-01-01

Prominent crater chains on Ganymede and Callisto are most likely the impact scars of comets tidally disrupted by Jupiter and are not secondary crater chains. We have examined the morphology of these chains in detail in order to place constraints on the properties of the comets that formed them and the disruption process. In these chains, intercrater spacing varies by no more than a factor of 2 and the craters within a given chain show almost no deviation from linearity (although the chains themselves are on gently curved small circles). All of these crater chains occur on or very near the Jupiter-facing hemisphere. For a given chain, the estimated masses of the fragments that formed each crater vary by no more than an order of magnitude. The mean fragment masses for all the chains vary by over four orders of magnitude (W. B. McKinnon and P. M. Schenk 1995, Geophys. Res. Lett. 13, 1829-1832), however. The mass of the parent comet for each crater chain is not correlated with the number of fragments produced during disruption but is correlated with the mean mass of the fragments produced in a given disruption event. Also, the larger fragments are located near the center of each chain. All of these characteristics are consistent with those predicted by disruption simulations based on the rubble pile cometary nucleus model (in which nuclei are composed on numerous small fragments weakly bound by self-gravity), and with those observed in Comet D/Shoemaker-Levy 9. Similar crater chains have not been found on the other icy satellites, but the impact record of disrupted comets on Callisto and Ganymede indicates that disruption events occur within the Jupiter system roughly once every 200 to 400 years.

Near-real time orbit determination for the GPS, CHAMP, GRACE, TerraSAR-X, and TanDEM-X satellites

NASA Astrophysics Data System (ADS)

Michalak, Grzegorz; Koenig, Rolf

The GFZ German Research Centre for Geosciences developed a near-real time (NRT) orbit gen-eration system for GPS and Low Earth Orbiting (LEO) satellites to support radio occultation data processing for the CHAMP, GRACE, Terra-SAR-X and the upcoming TanDEM-X mis-sions and fast baseline determination for the TanDEM-X mission. Precise NRT orbits are being generated for the CHAMP and GRACE-A satellites since August 2006 and for TerraSAR-X since August 2007. For each LEO, the system consists of three independent chains delivering NRT orbits with different latencies and accuracies. The first chain generates in a preceding step NRT GPS orbits and clock biases and based thereon LEO orbits with delays of 30 minutes counted from the last measurement point to the time the orbit product is available. The orbit accuracies can be assessed via Satellite Laser Ranging (SLR) to 7 cm. The second chain is based on predicted GPS orbits from the International GNSS Service (IGS) but endowed with in-house estimated clock biases. This chain generates orbits with the same latency of 30 minutes but with better accuracies of 5 cm SLR RMS. The third chain, the least accurate but the fastest, is based on predicted IGS GPS orbits and clocks and delivers LEO orbits with latencies of 13 minutes and accuracies of 10 cm SLR RMS. The system design is such that it can easily be extended to cope with new satellites like TanDEM-X requiring precise and fast available orbits.

Stability of uncertain systems. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Blankenship, G. L.

1971-01-01

The asymptotic properties of feedback systems are discussed, containing uncertain parameters and subjected to stochastic perturbations. The approach is functional analytic in flavor and thereby avoids the use of Markov techniques and auxiliary Lyapunov functionals characteristic of the existing work in this area. The results are given for the probability distributions of the accessible signals in the system and are proved using the Prohorov theory of the convergence of measures. For general nonlinear systems, a result similar to the small loop-gain theorem of deterministic stability theory is given. Boundedness is a property of the induced distributions of the signals and not the usual notion of boundedness in norm. For the special class of feedback systems formed by the cascade of a white noise, a sector nonlinearity and convolution operator conditions are given to insure the total boundedness of the overall feedback system.

Dynamic Uncertain Causality Graph for Knowledge Representation and Reasoning: Utilization of Statistical Data and Domain Knowledge in Complex Cases.

PubMed

Zhang, Qin; Yao, Quanying

2018-05-01

The dynamic uncertain causality graph (DUCG) is a newly presented framework for uncertain causality representation and probabilistic reasoning. It has been successfully applied to online fault diagnoses of large, complex industrial systems, and decease diagnoses. This paper extends the DUCG to model more complex cases than what could be previously modeled, e.g., the case in which statistical data are in different groups with or without overlap, and some domain knowledge and actions (new variables with uncertain causalities) are introduced. In other words, this paper proposes to use -mode, -mode, and -mode of the DUCG to model such complex cases and then transform them into either the standard -mode or the standard -mode. In the former situation, if no directed cyclic graph is involved, the transformed result is simply a Bayesian network (BN), and existing inference methods for BNs can be applied. In the latter situation, an inference method based on the DUCG is proposed. Examples are provided to illustrate the methodology.

Formation Learning Control of Multiple Autonomous Underwater Vehicles With Heterogeneous Nonlinear Uncertain Dynamics.

PubMed

Yuan, Chengzhi; Licht, Stephen; He, Haibo

2017-09-26

In this paper, a new concept of formation learning control is introduced to the field of formation control of multiple autonomous underwater vehicles (AUVs), which specifies a joint objective of distributed formation tracking control and learning/identification of nonlinear uncertain AUV dynamics. A novel two-layer distributed formation learning control scheme is proposed, which consists of an upper-layer distributed adaptive observer and a lower-layer decentralized deterministic learning controller. This new formation learning control scheme advances existing techniques in three important ways: 1) the multi-AUV system under consideration has heterogeneous nonlinear uncertain dynamics; 2) the formation learning control protocol can be designed and implemented by each local AUV agent in a fully distributed fashion without using any global information; and 3) in addition to the formation control performance, the distributed control protocol is also capable of accurately identifying the AUVs' heterogeneous nonlinear uncertain dynamics and utilizing experiences to improve formation control performance. Extensive simulations have been conducted to demonstrate the effectiveness of the proposed results.

Solution-Phase Conformation and Dynamics of Conjugated Isoindigo-Based Donor–Acceptor Polymer Single Chains

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

Lee, Franklin L.; Farimani, Amir Barati; Gu, Kevin L.

Conjugated polymers are the key material in thin-film organic optoelectronic devices due to the versatility of these molecules combined with their semiconducting properties. A molecular-scale understanding of conjugated polymers is important to the optimization of the thin-film morphology. We examine the solution-phase behavior of conjugated isoindigo-based donor–acceptor polymer single chains of various chain lengths using atomistic molecular dynamics simulations. Our simulations elucidate the transition from a rod-like to a coil-like conformation from an analysis of normal modes and persistence length. In addition, we find another transition based on the solvent environment, contrasting the coil-like conformation in a good solvent withmore » a globule-like conformation in a poor solvent. Altogether, our results provide valuable insights into the transition between conformational regimes for conjugated polymers as a function of both the chain length and the solvent environment, which will help to accurately parametrize higher level models.« less

Solution-Phase Conformation and Dynamics of Conjugated Isoindigo-Based Donor–Acceptor Polymer Single Chains

DOE PAGES

Lee, Franklin L.; Farimani, Amir Barati; Gu, Kevin L.; ...

2017-10-25

Conjugated polymers are the key material in thin-film organic optoelectronic devices due to the versatility of these molecules combined with their semiconducting properties. A molecular-scale understanding of conjugated polymers is important to the optimization of the thin-film morphology. We examine the solution-phase behavior of conjugated isoindigo-based donor–acceptor polymer single chains of various chain lengths using atomistic molecular dynamics simulations. Our simulations elucidate the transition from a rod-like to a coil-like conformation from an analysis of normal modes and persistence length. In addition, we find another transition based on the solvent environment, contrasting the coil-like conformation in a good solvent withmore » a globule-like conformation in a poor solvent. Altogether, our results provide valuable insights into the transition between conformational regimes for conjugated polymers as a function of both the chain length and the solvent environment, which will help to accurately parametrize higher level models.« less

A gene encoding the plant-like alternative oxidase is present in Phytomonas but absent in Leishmania spp.

PubMed

Van Hellemond, J J; Simons, B; Millenaar, F F; Tielens, A G

1998-01-01

The constituents of the respiratory chain are believed to differ among the trypanosomatids; bloodstream stages of African trypanosomes and Phytomonas promastigotes oxidize ubiquinol by a ubiquinol:oxygen oxidoreductase, also known as alternative oxidase, whereas Leishmania spp. oxidize ubiquinol via a classic cytochrome-containing respiratory chain. The molecular basis for this elementary difference in ubiquinol oxidation by the mitochondrial electron-transport chain in distinct trypanosomatids was investigated. The presence of a gene encoding the plant-like alternative oxidase could be demonstrated in Phytomonas and Trypanosoma brucei, trypanosomatids that are known to contain alternative oxidase activity. Our results further demonstrated that Leishmania spp. lack a gene encoding the plant-like alternative oxidase, and therefore, all stages of Leishmania spp. will lack the alternative oxidase protein. The observed fundamental differences between the respiratory chains of distinct members of the trypanosomatid family are thus caused by the presence or absence of a gene encoding the plant-like alternative oxidase.

Helmholtz and Gibbs ensembles, thermodynamic limit and bistability in polymer lattice models

NASA Astrophysics Data System (ADS)

Giordano, Stefano

2017-12-01

Representing polymers by random walks on a lattice is a fruitful approach largely exploited to study configurational statistics of polymer chains and to develop efficient Monte Carlo algorithms. Nevertheless, the stretching and the folding/unfolding of polymer chains within the Gibbs (isotensional) and the Helmholtz (isometric) ensembles of the statistical mechanics have not been yet thoroughly analysed by means of the lattice methodology. This topic, motivated by the recent introduction of several single-molecule force spectroscopy techniques, is investigated in the present paper. In particular, we analyse the force-extension curves under the Gibbs and Helmholtz conditions and we give a proof of the ensembles equivalence in the thermodynamic limit for polymers represented by a standard random walk on a lattice. Then, we generalize these concepts for lattice polymers that can undergo conformational transitions or, equivalently, for chains composed of bistable or two-state elements (that can be either folded or unfolded). In this case, the isotensional condition leads to a plateau-like force-extension response, whereas the isometric condition causes a sawtooth-like force-extension curve, as predicted by numerous experiments. The equivalence of the ensembles is finally proved also for lattice polymer systems exhibiting conformational transitions.

Signal Processing Expert Code (SPEC)

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

Ames, H.S.

1985-12-01

The purpose of this paper is to describe a prototype expert system called SPEC which was developed to demonstrate the utility of providing an intelligent interface for users of SIG, a general purpose signal processing code. The expert system is written in NIL, runs on a VAX 11/750 and consists of a backward chaining inference engine and an English-like parser. The inference engine uses knowledge encoded as rules about the formats of SIG commands and about how to perform frequency analyses using SIG. The system demonstrated that expert system can be used to control existing codes.

Dynamics of metastable breathers in nonlinear chains in acoustic vacuum

NASA Astrophysics Data System (ADS)

Sen, Surajit; Mohan, T. R. Krishna

2009-03-01

The study of the dynamics of one-dimensional chains with both harmonic and nonlinear interactions, as in the Fermi-Pasta-Ulam and related problems, has played a central role in efforts to identify the broad consequences of nonlinearity in these systems. Nevertheless, little is known about the dynamical behavior of purely nonlinear chains where there is a complete absence of the harmonic term, and hence sound propagation is not admissible, i.e., under conditions of “acoustic vacuum.” Here we study the dynamics of highly localized excitations, or breathers, which are known to be initiated by the quasistatic stretching of the bonds between adjacent particles. We show via detailed particle-dynamics-based studies that many low-energy pulses also form in the vicinity of the perturbation, and the breathers that form are “fragile” in the sense that they can be easily delocalized by scattering events in the system. We show that the localized excitations eventually disperse, allowing the system to attain an equilibrium-like state that is realizable in acoustic vacuum. We conclude with a discussion of how the dynamics is affected by the presence of acoustic oscillations.

The Climate Adaptation Frontier

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

Preston, Benjamin L

2013-01-01

Climate adaptation has emerged as a mainstream risk management strategy for assisting in maintaining socio-ecological systems within the boundaries of a safe operating space. Yet, there are limits to the ability of systems to adapt. Here, we introduce the concept of an adaptation frontier , which is defined as a socio-ecological system s transitional adaptive operating space between safe and unsafe domains. A number of driving forces are responsible for determining the sustainability of systems on the frontier. These include path dependence, adaptation/development deficits, values conflicts and discounting of future loss and damage. The cumulative implications of these driving forcesmore » are highly uncertain. Nevertheless, the fact that a broad range of systems already persist at the edge of their frontiers suggests a high likelihood that some limits will eventually be exceeded. The resulting system transformation is likely to manifest as anticipatory modification of management objectives or loss and damage. These outcomes vary significantly with respect to their ethical implications. Successful navigation of the adaptation frontier will necessitate new paradigms of risk governance to elicit knowledge that encourages reflexive reevaluation of societal values that enable or constrain sustainability.« less

Out-of-time-ordered correlators in a quantum Ising chain

NASA Astrophysics Data System (ADS)

Lin, Cheng-Ju; Motrunich, Olexei I.

2018-04-01

Out-of-time-ordered correlators (OTOC) have been proposed to characterize quantum chaos in generic systems. However, they can also show interesting behavior in integrable models, resembling the OTOC in chaotic systems in some aspects. Here we study the OTOC for different operators in the exactly-solvable one-dimensional quantum Ising spin chain. The OTOC for spin operators that are local in terms of the Jordan-Wigner fermions has a "shell-like" structure: After the wavefront passes, the OTOC approaches its original value in the long-time limit, showing no signature of scrambling; the approach is described by a t-1 power law at long time t . On the other hand, the OTOC for spin operators that are nonlocal in the Jordan-Wigner fermions has a "ball-like" structure, with its value reaching zero in the long-time limit, looking like a signature of scrambling; the approach to zero, however, is described by a slow power law t-1 /4 for the Ising model at the critical coupling. These long-time power-law behaviors in the lattice model are not captured by conformal field theory calculations. The mixed OTOC with both local and nonlocal operators in the Jordan-Wigner fermions also has a "ball-like" structure, but the limiting values and the decay behavior appear to be nonuniversal. In all cases, we are not able to define a parametrically large window around the wavefront to extract the Lyapunov exponent.

A modified hybrid uncertain analysis method for dynamic response field of the LSOAAC with random and interval parameters

NASA Astrophysics Data System (ADS)

Zi, Bin; Zhou, Bin

2016-07-01

For the prediction of dynamic response field of the luffing system of an automobile crane (LSOAAC) with random and interval parameters, a hybrid uncertain model is introduced. In the hybrid uncertain model, the parameters with certain probability distribution are modeled as random variables, whereas, the parameters with lower and upper bounds are modeled as interval variables instead of given precise values. Based on the hybrid uncertain model, the hybrid uncertain dynamic response equilibrium equation, in which different random and interval parameters are simultaneously included in input and output terms, is constructed. Then a modified hybrid uncertain analysis method (MHUAM) is proposed. In the MHUAM, based on random interval perturbation method, the first-order Taylor series expansion and the first-order Neumann series, the dynamic response expression of the LSOAAC is developed. Moreover, the mathematical characteristics of extrema of bounds of dynamic response are determined by random interval moment method and monotonic analysis technique. Compared with the hybrid Monte Carlo method (HMCM) and interval perturbation method (IPM), numerical results show the feasibility and efficiency of the MHUAM for solving the hybrid LSOAAC problems. The effects of different uncertain models and parameters on the LSOAAC response field are also investigated deeply, and numerical results indicate that the impact made by the randomness in the thrust of the luffing cylinder F is larger than that made by the gravity of the weight in suspension Q . In addition, the impact made by the uncertainty in the displacement between the lower end of the lifting arm and the luffing cylinder a is larger than that made by the length of the lifting arm L .

Robot Path Planning in Uncertain Environments: A Language Measure-theoretic Approach

DTIC Science & Technology

2014-01-01

Paper DS-14-1028 to appear in the Special Issue on Stochastic Models, Control and Algorithms in Robotics, ASME Journal of Dynamic Systems...Measurement and Control Robot Path Planning in Uncertain Environments: A Language Measure-theoretic Approach⋆ Devesh K. Jha† Yue Li† Thomas A. Wettergren‡† Asok...algorithm, called ν⋆, that was formulated in the framework of probabilistic finite state automata (PFSA) and language measure from a control -theoretic

Network systems security analysis

NASA Astrophysics Data System (ADS)

Yilmaz, Ä.°smail

2015-05-01

Network Systems Security Analysis has utmost importance in today's world. Many companies, like banks which give priority to data management, test their own data security systems with "Penetration Tests" by time to time. In this context, companies must also test their own network/server systems and take precautions, as the data security draws attention. Based on this idea, the study cyber-attacks are researched throughoutly and Penetration Test technics are examined. With these information on, classification is made for the cyber-attacks and later network systems' security is tested systematically. After the testing period, all data is reported and filed for future reference. Consequently, it is found out that human beings are the weakest circle of the chain and simple mistakes may unintentionally cause huge problems. Thus, it is clear that some precautions must be taken to avoid such threats like updating the security software.

Teaching Wave Propagation and the Emergence of Viete's Formula

ERIC Educational Resources Information Center

Cullerne, J. P.; Goekjian, M. C. Dunn

2012-01-01

The well-known result for the frequency of a simple spring-mass system may be combined with elementary concepts like speed = wavelength x frequency to obtain wave propagation speeds for an infinite chain of springs and masses (masses "m" held apart at equilibrium distance "a" by springs of stiffness "gamma"). These propagation speeds are dependent…

Supply Chain Simulator: A Scenario-Based Educational Tool to Enhance Student Learning

ERIC Educational Resources Information Center

Siddiqui, Atiq; Khan, Mehmood; Akhtar, Sohail

2008-01-01

Simulation-based educational products are excellent set of illustrative tools that proffer features like visualization of the dynamic behavior of a real system, etc. Such products have great efficacy in education and are known to be one of the first-rate student centered learning methodologies. These products allow students to practice skills such…

The endothelial glycocalyx

PubMed Central

Yang, Yimu; Schmidt, Eric P.

2013-01-01

Once thought to be a structure of small size and uncertain significance, the endothelial glycocalyx is now known to be an important regulator of endothelial function. Studies of the systemic vasculature have demonstrated that the glycocalyx forms a substantial in vivo endothelial surface layer (ESL) critical to inflammation, barrier function and mechanotransduction. The pulmonary ESL is significantly thicker than the systemic ESL, suggesting unique physiologic function. We have recently demonstrated that the pulmonary ESL regulates exposure of endothelial surface adhesion molecules, thereby serving as a barrier to neutrophil adhesion and extravasation. While the pulmonary ESL is not a critical structural component of the endothelial barrier to fluid and protein, it serves a major role in the mechanotransduction of vascular pressure, with impact on the active regulation of endothelial permeability. It is likely that the ESL serves numerous additional functions in vascular physiology, representing a fertile area for future investigation. PMID:24073386

Toll-like receptor signaling and its relevance to intestinal inflammation.

PubMed

Cario, Elke; Podolsky, Daniel K

2006-08-01

This review discusses the current progress in the understanding of how commensal-mediated activation of toll-like receptors (TLRs) may be involved in the regulation of physiological and pathophysiological processes of the intestinal mucosa including tissue regeneration and inflammation. While regulation of TLRs and their downstream signaling mediators might be used to prevent and treat inflammatory bowel diseases, paradoxically, at this time, it remains uncertain whether this would be more effectively accomplished by enhancing or inhibiting these pathways.

Teacher Education and Posthumanism

ERIC Educational Resources Information Center

Howlett, Caitlin

2018-01-01

Education faces a tenuous future, straddling a growing divide between a no-longer-relevant past and an uncertain future, a future that calls into question the future of humanity altogether. In the face of such a future, posthumanism stands as a reminder that the divides we make in education are unstable, that things could and likely will be…

Rationales for Indirect Speech: The Theory of the Strategic Speaker

ERIC Educational Resources Information Center

Lee, James J.; Pinker, Steven

2010-01-01

Speakers often do not state requests directly but employ innuendos such as "Would you like to see my etchings?" Though such indirectness seems puzzlingly inefficient, it can be explained by a theory of the "strategic speaker", who seeks plausible deniability when he or she is uncertain of whether the hearer is cooperative or…

Beyond Jefferson: The Rhetoric of Meritocracy and the Funding of Public Education

ERIC Educational Resources Information Center

Nicholson, Barbara

2003-01-01

This article presents an excerpt of a declaration from the United States Department of Education's "Strategic Plan: 2002-2007." The declaration signifies in no uncertain terms that the battle waged by critics of alternative research methods continues, and is likely to intensify. The denigration of research methods which decline to adhere…

A historical note on the association between the legal status of expedited partner therapy and physician practice.

PubMed

Cramer, Ryan; Hogben, Matthew; Handsfield, H Hunter

2013-05-01

Potential legal liability for practicing expedited partner therapy is a common concern among providers, although it has been uncertain how these concerns translate into clinical practice. This study suggests that providers are more likely to practice expedited partner therapy in more favorable legal environments.

You Say "Probable" and I Say "Likely": Improving Interpersonal Communication With Verbal Probability Phrases

ERIC Educational Resources Information Center

Karelitz, Tzur M.; Budescu, David V.

2004-01-01

When forecasters and decision makers describe uncertain events using verbal probability terms, there is a risk of miscommunication because people use different probability phrases and interpret them in different ways. In an effort to facilitate the communication process, the authors investigated various ways of converting the forecasters' verbal…

Queer and Trans Youth, Relational Subjectivity, and Uncertain Possibilities: Challenging Research in Complicated Contexts

ERIC Educational Resources Information Center

Mayo, Cris

2017-01-01

This article addresses complications to how different disciplines define, study, and theorize sexuality, gender, gender identity, and other intersecting categories of subjectivity, like age, race, class, ethnicity, and so on. Categories that seem to get stabilized in empirical work are destabilized in theoretical and narrative research. These…

The High Costs and Doubtful Efficacy of Extended Teacher-Preparation Programs: An Invitation to More Basic Reforms.

ERIC Educational Resources Information Center

Hawley, Willis D.

1987-01-01

Extended programs are likely to reduce the quality and quantity of teachers and probably will not improve teacher performance. Because the risks of extended programs are great and the benefits uncertain, other strategies for improving teacher education should be explored more aggressively. (Author/LHW)

Brush-Like Polymers: New Design Platforms for Soft, Dry Materials with Unique Property Relations

NASA Astrophysics Data System (ADS)

Daniel, William Francis McKemie, Jr.

Elastomers represent a unique class of engineering materials due to their light weight, low cost, and desirable combination of softness (105 -107 Pa) and large extensibilities (up to 1000%). Despite these advantages, there exist applications that require many times softer modulus, greater extensibility, and stronger strain hardening for the purpose of mimicking the mechanical properties of systems such as biological tissues. Until recently, only liquid-filled gels were suitable materials for such applications, including soft robotics and implants. A considerable amount of work has been done to create gels with superior properties, but despite unique strengths they also suffer from unique weaknesses. This class of material displays fundamental limitations in the form of heterogeneous structures, solvent loss and phase transitions at extreme temperatures, and loss of liquid fraction upon high deformations. In gels the solvent fraction also introduces a large solvent/polymer interaction parameter which must be carefully considered when designing the final mechanical properties. These energetic considerations further exaggerate the capacity for inconstant mechanical properties caused by fluctuations of the solvent fraction. In order to overcome these weaknesses, a new platform for single component materials with low modulus (<105 Pa) must be developed. Single component systems do not suffer from compositional changes over time and display more stable performance in a wider variety of temperatures and humidity conditions. A solvent-free system also has the potential to be homogeneous which replaces the large energetic interactions with comparatively small architectural interaction parameters. If a solvent-free alternative to liquid-filled gels is to be created, we must first consider the fundamental barrier to softer elastomers, i.e. entanglements - intrinsic topological restrains which define a lower limit of modulus ( 105 Pa). These entanglements are determined by chemistry specific parameters (repeat unit volume and Kuhn segment size) in the polymer liquid (melt) prior to crosslinking. Previous solvent free replacements for gels include elastomers end-linked in semidilute conditions. These materials are generated through crosslinking telechelic polymer chains in semidilute solutions at the onset of chain overlap. At such low polymer concentrations entanglements are greatly diluted and once the resulting gel is dried it creates a supersoft and super-elastic network. Although such methods have successfully generated materials with moduli below the 105 Pa limit and high extensibilities ( 1000%) they present their own limitations. Firstly, the semidilute crosslinking methods uses an impractically large volume of solvent which is unattractive in industry. Second, producing and crosslinking large monodisperse telechelic chains is a nontrivial process leading to large uncertainties in the final network architecture and properties. Specifically, telechelics have a distribution of end-to-end distances and in semidilute solutions with extremely low fraction of chain ends the crosslink reaction is diffusion limited, very slow, and imprecise. In order to achieve a superior solvent-free platform, we propose alteration of mechanical properties through the architectural disentanglement of brush-like polymer structures. In recent year there has been an increase in the synthetic conditions and crosslinking schemes available for producing brush-like structures. This makes brush-like materials an attractive alternative to more restrictive methods such as end-linking. Standard networks have one major control factor outside of chemistry, the network stand length. Brush-like architectures are created from long strands with regularly grafted side chains creating three characteristic length scales which may be independently manipulated. In collaboration with M. Rubinstein, we have utilized bottlebrush polymer architectures (a densely grafted brush-like polymer) to experimentally verify theoretical predictions of disentangled bottlebrush melts. By attaching well-defined side chains onto long polymer backbones, individual polymer strands are separated in space (similar to dilution with solvent) accompanied by a comparatively small increase in the rigidity of the strands. The end result is an architectural disentangled melt with an entanglement plateau modulus as much as three orders of magnitude lower than typical linear polymers and a broadly expanded potential for extensibility once crosslinked.

Analysis Tools for Interconnected Boolean Networks With Biological Applications.

PubMed

Chaves, Madalena; Tournier, Laurent

2018-01-01

Boolean networks with asynchronous updates are a class of logical models particularly well adapted to describe the dynamics of biological networks with uncertain measures. The state space of these models can be described by an asynchronous state transition graph, which represents all the possible exits from every single state, and gives a global image of all the possible trajectories of the system. In addition, the asynchronous state transition graph can be associated with an absorbing Markov chain, further providing a semi-quantitative framework where it becomes possible to compute probabilities for the different trajectories. For large networks, however, such direct analyses become computationally untractable, given the exponential dimension of the graph. Exploiting the general modularity of biological systems, we have introduced the novel concept of asymptotic graph , computed as an interconnection of several asynchronous transition graphs and recovering all asymptotic behaviors of a large interconnected system from the behavior of its smaller modules. From a modeling point of view, the interconnection of networks is very useful to address for instance the interplay between known biological modules and to test different hypotheses on the nature of their mutual regulatory links. This paper develops two new features of this general methodology: a quantitative dimension is added to the asymptotic graph, through the computation of relative probabilities for each final attractor and a companion cross-graph is introduced to complement the method on a theoretical point of view.

A new design of robust H∞ sliding mode control for uncertain stochastic T-S fuzzy time-delay systems.

PubMed

Gao, Qing; Feng, Gang; Xi, Zhiyu; Wang, Yong; Qiu, Jianbin

2014-09-01

In this paper, a novel dynamic sliding mode control scheme is proposed for a class of uncertain stochastic nonlinear time-delay systems represented by Takagi-Sugeno fuzzy models. The key advantage of the proposed scheme is that two very restrictive assumptions in most existing sliding mode control approaches for stochastic fuzzy systems have been removed. It is shown that the closed-loop control system trajectories can be driven onto the sliding surface in finite time almost certainly. It is also shown that the stochastic stability of the resulting sliding motion can be guaranteed in terms of linear matrix inequalities; moreover, the sliding-mode controller can be obtained simultaneously. Simulation results illustrating the advantages and effectiveness of the proposed approaches are also provided.

Path-integral theory of an axially confined worm-like chain

NASA Astrophysics Data System (ADS)

Smith, D. A.

2001-06-01

A path-integral formulation is developed for the thermodynamic properties of a worm-like chain moving on a surface and laterally confined by a harmonic potential. The free energy of the chain is calculated as a function of its length and boundary conditions at each end. Distribution functions for chain displacements can be constructed by utilizing the Markov property as a function of displacement φ(s) and its derivative dφ(s)/ds along the path. These quantities are also calculated in the presence of pinning sites which impose fixed positive or negative displacements, foreshadowing their application to a model for the regulation of striated muscle.

Robust decentralised stabilisation of uncertain large-scale interconnected nonlinear descriptor systems via proportional plus derivative feedback

NASA Astrophysics Data System (ADS)

Li, Jian; Zhang, Qingling; Ren, Junchao; Zhang, Yanhao

2017-10-01

This paper studies the problem of robust stability and stabilisation for uncertain large-scale interconnected nonlinear descriptor systems via proportional plus derivative state feedback or proportional plus derivative output feedback. The basic idea of this work is to use the well-known differential mean value theorem to deal with the nonlinear model such that the considered nonlinear descriptor systems can be transformed into linear parameter varying systems. By using a parameter-dependent Lyapunov function, a decentralised proportional plus derivative state feedback controller and decentralised proportional plus derivative output feedback controller are designed, respectively such that the closed-loop system is quadratically normal and quadratically stable. Finally, a hypersonic vehicle practical simulation example and numerical example are given to illustrate the effectiveness of the results obtained in this paper.

Robust nonlinear variable selective control for networked systems

NASA Astrophysics Data System (ADS)

Rahmani, Behrooz

2016-10-01

This paper is concerned with the networked control of a class of uncertain nonlinear systems. In this way, Takagi-Sugeno (T-S) fuzzy modelling is used to extend the previously proposed variable selective control (VSC) methodology to nonlinear systems. This extension is based upon the decomposition of the nonlinear system to a set of fuzzy-blended locally linearised subsystems and further application of the VSC methodology to each subsystem. To increase the applicability of the T-S approach for uncertain nonlinear networked control systems, this study considers the asynchronous premise variables in the plant and the controller, and then introduces a robust stability analysis and control synthesis. The resulting optimal switching-fuzzy controller provides a minimum guaranteed cost on an H2 performance index. Simulation studies on three nonlinear benchmark problems demonstrate the effectiveness of the proposed method.

Configuration of the magnetosome chain: a natural magnetic nanoarchitecture.

PubMed

Orue, I; Marcano, L; Bender, P; García-Prieto, A; Valencia, S; Mawass, M A; Gil-Cartón, D; Alba Venero, D; Honecker, D; García-Arribas, A; Fernández Barquín, L; Muela, A; Fdez-Gubieda, M L

2018-04-26

Magnetospirillum gryphiswaldense is a microorganism with the ability to biomineralize magnetite nanoparticles, called magnetosomes, and arrange them into a chain that behaves like a magnetic compass. Rather than straight lines, magnetosome chains are slightly bent, as evidenced by electron cryotomography. Our experimental and theoretical results suggest that due to the competition between the magnetocrystalline and shape anisotropies, the effective magnetic moment of individual magnetosomes is tilted out of the [111] crystallographic easy axis of magnetite. This tilt does not affect the direction of the chain net magnetic moment, which remains along the [111] axis, but explains the arrangement of magnetosomes in helical-like shaped chains. Indeed, we demonstrate that the chain shape can be reproduced by considering an interplay between the magnetic dipolar interactions between magnetosomes, ruled by the orientation of the magnetosome magnetic moment, and a lipid/protein-based mechanism, modeled as an elastic recovery force exerted on the magnetosomes.

Herpes simplex virus type 2 recurrent meningitis (Mollaret's meningitis): a consideration for the recurrent pathogenesis.

PubMed

Sato, Rumi; Ayabe, Mitsuyoshi; Shoji, Hiroshi; Ichiyama, Takashi; Saito, Yumiko; Hondo, Ryo; Eizuru, Yoshito

2005-11-01

We report a 44-year-old Japanese woman with herpes simplex virus (HSV) type 2 recurrent meningitis (Mollaret's meningitis). The diagnosis was confirmed by nested polymerase chain reaction in her cerebrospinal fluid, but the patient's conventional HSV antibodies by complement fixation, neutralizing test or enzyme immunoassay showed low titres with low lymphoproliferative response. Several similar cases are discussed. Although the reason for the recurrent pathogenesis is uncertain, our report suggests that the low immune response including immune evasion may be involved in the pathogenesis of HSV type 2 recurrent meningitis. For this patient, long-term suppressive and patient-initiated therapies were conducted to prevent the recurrence of meningitis.

Climate change and floods - findings and adaptation strategies for flood protection in Baden-Württemberg.

PubMed

Hennegriff, W

2007-01-01

The climatic conditions in Southern Germany have changed noticeably in the 20th century, especially during the last three decades. Both in specific regions and interannually, the trends found exceed the natural margins of deviation previously known from long measurement series for some measured quantities. The mean and also the extreme floods are expected to increase significantly, although the results of the model chain global model-regional climate models-water balance models are still uncertain. As a precaution an adaptation strategy has been developed for the field of flood protection which takes into consideration the possible development for the next decades and also takes into account the uncertainties.

Exact solutions for discrete breathers in a forced-damped chain.

PubMed

Gendelman, O V

2013-06-01

Exact solutions for symmetric on-site discrete breathers (DBs) are obtained in a forced-damped linear chain with on-site vibro-impact constraints. The damping in the system is caused by inelastic impacts; the forcing functions should satisfy conditions of periodicity and antisymmetry. Global conditions for existence and stability of the DBs are established by a combination of analytic and numeric methods. The DB can lose its stability through either pitchfork, or Neimark-Sacker bifurcations. The pitchfork bifurcation is related to the internal dynamics of each individual oscillator. It is revealed that the coupling can suppress this type of instability. To the contrary, the Neimark-Sacker bifurcation occurs for relatively large values of the coupling, presumably due to closeness of the excitation frequency to a boundary of the propagation zone of the chain. Both bifurcation mechanisms seem to be generic for the considered type of forced-damped lattices. Some unusual phenomena, like nonmonotonous dependence of the stability boundary on the forcing amplitude, are revealed analytically for the initial system and illustrated numerically for small periodic lattices.

Assessing stability and performance of a digitally enabled supply chain: Retrospective of a pilot in Uttar Pradesh, India.

PubMed

Gilbert, Sarah Skye; Thakare, Neeraj; Ramanujapuram, Arun; Akkihal, Anup

2017-04-19

Immunization supply chains in low resource settings do not always reach children with necessary vaccines. Digital information systems can enable real time visibility of inventory and improve vaccine availability. In 2014, a digital, mobile/web-based information system was implemented in two districts of Uttar Pradesh, India. This retrospective investigates improvements and stabilization of supply chain performance following introduction of the digital information system. All data were collected via the digital information system between March 2014 and September 2015. Data included metadata and transaction logs providing information about users, facilities, and vaccines. Metrics evaluated include adoption (system access, timeliness and completeness), data quality (error rates), and performance (stock availability on immunization session days, replenishment response duration, rate of zero stock events). Stability was defined as the phase in which quality and performance metrics achieved equilibrium rates with minimal volatility. The analysis compared performance across different facilities and vaccines. Adoption appeared sufficiently high from the onset to commence stability measures of data quality and supply chain performance. Data quality stabilized from month 3 onwards, and supply chain performance stabilized from month 13 onwards. For data quality, error rates reduced by two thirds post stabilization. Although vaccine availability remained high throughout the pilot, the three lowest-performing facilities improved from 91.05% pre-stability to 98.70% post-stability (p<0.01; t-test). Average replenishment duration (as a corrective response to stock-out events) decreased 52.3% from 4.93days to 2.35days (p<0.01; t-test). Diphtheria-tetanus-pertussis vaccine was significantly less likely to be stocked out than any other material. The results suggest that given sufficient adoption, stability is sequentially achieved, beginning with data quality, and then performance. Identifying when a pilot stabilizes can enable more predictable, reliable cost estimates, and outcome forecasts in the scale-up phase. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Regional robust stabilisation and domain-of-attraction estimation for MIMO uncertain nonlinear systems with input saturation

NASA Astrophysics Data System (ADS)

Azizi, S.; Torres, L. A. B.; Palhares, R. M.

2018-01-01

The regional robust stabilisation by means of linear time-invariant state feedback control for a class of uncertain MIMO nonlinear systems with parametric uncertainties and control input saturation is investigated. The nonlinear systems are described in a differential algebraic representation and the regional stability is handled considering the largest ellipsoidal domain-of-attraction (DOA) inside a given polytopic region in the state space. A novel set of sufficient Linear Matrix Inequality (LMI) conditions with new auxiliary decision variables are developed aiming to design less conservative linear state feedback controllers with corresponding larger DOAs, by considering the polytopic description of the saturated inputs. A few examples are presented showing favourable comparisons with recently published similar control design methodologies.

Robust adaptive fault-tolerant control for leader-follower flocking of uncertain multi-agent systems with actuator failure.

PubMed

Yazdani, Sahar; Haeri, Mohammad

2017-11-01

In this work, we study the flocking problem of multi-agent systems with uncertain dynamics subject to actuator failure and external disturbances. By considering some standard assumptions, we propose a robust adaptive fault tolerant protocol for compensating of the actuator bias fault, the partial loss of actuator effectiveness fault, the model uncertainties, and external disturbances. Under the designed protocol, velocity convergence of agents to that of virtual leader is guaranteed while the connectivity preservation of network and collision avoidance among agents are ensured as well. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Decentralized Adaptive Control of Systems with Uncertain Interconnections, Plant-Model Mismatch and Actuator Failures

NASA Technical Reports Server (NTRS)

Patre, Parag; Joshi, Suresh M.

2011-01-01

Decentralized adaptive control is considered for systems consisting of multiple interconnected subsystems. It is assumed that each subsystem s parameters are uncertain and the interconnection parameters are not known. In addition, mismatch can exist between each subsystem and its reference model. A strictly decentralized adaptive control scheme is developed, wherein each subsystem has access only to its own state but has the knowledge of all reference model states. The mismatch is estimated online for each subsystem and the mismatch estimates are used to adaptively modify the corresponding reference models. The adaptive control scheme is extended to the case with actuator failures in addition to mismatch.

Causal uncertainty, claimed and behavioural self-handicapping.

PubMed

Thompson, Ted; Hepburn, Jonathan

2003-06-01

Causal uncertainty beliefs involve doubts about the causes of events, and arise as a consequence of non-contingent evaluative feedback: feedback that leaves the individual uncertain about the causes of his or her achievement outcomes. Individuals high in causal uncertainty are frequently unable to confidently attribute their achievement outcomes, experience anxiety in achievement situations and as a consequence are likely to engage in self-handicapping behaviour. Accordingly, we sought to establish links between trait causal uncertainty, claimed and behavioural self-handicapping. Participants were N=72 undergraduate students divided equally between high and low causally uncertain groups. We used a 2 (causal uncertainty status: high, low) x 3 (performance feedback condition: success, non-contingent success, non-contingent failure) between-subjects factorial design to examine the effects of causal uncertainty on achievement behaviour. Following performance feedback, participants completed 20 single-solution anagrams and 12 remote associate tasks serving as performance measures, and 16 unicursal tasks to assess practice effort. Participants also completed measures of claimed handicaps, state anxiety and attributions. Relative to low causally uncertain participants, high causally uncertain participants claimed more handicaps prior to performance on the anagrams and remote associates, reported higher anxiety, attributed their failure to internal, stable factors, and reduced practice effort on the unicursal tasks, evident in fewer unicursal tasks solved. These findings confirm links between trait causal uncertainty and claimed and behavioural self-handicapping, highlighting the need for educators to facilitate means by which students can achieve surety in the manner in which they attribute the causes of their achievement outcomes.

Design and analysis of the Gemini chain system in dual clutch transmission of automobile

NASA Astrophysics Data System (ADS)

Cheng, Yabing; Guo, Haitao; Fu, Zhenming; Wan, Nen; Li, Lei; Wang, Yang

2015-01-01

Chain drive system is widely used in the conditions of high-speed, overload, variable speed and load. Many studies are focused on the meshing theory and wear characteristics of chain drive system, but system design, analysis, and noise characteristics of the chain drive system are weak. System design and noise characteristic are studied for a new type Gemini chain of dual-clutch automatic transmission. Based on the meshing theory of silent chain, the design parameters of the Gemini chain system are calculated and the mathematical models and dynamic analysis models of the Gemini chain system are established. Dynamic characteristics of the Gemini chain system is simulated and the contact force of plate and pin, plate and sprockets, the chain tension forces, the transmission error and the stress of plates and pins are analyzed. According to the simulation results of the Gemini chain system, the noise experiment about system is carried out. The noise values are tested at different speed and load and spectral characteristics are analyzed. The results of simulation and experimental show that the contact forces of plate and pin, plate and sprockets are smaller than the allowable stress values, the chain tension force is less than ultimate tension and transmission error is limited in 1.2%. The noise values can meet the requirements of industrial design, and it is proved that the design and analysis method of the Gemini chain system is scientific and feasible. The design and test system is built from analysis to test of Gemini chain system. This research presented will provide a corresponding theoretical guidance for the design and dynamic characteristics and noise characteristics of chain drive system.

The Symbiotic System SS73 17 seen with Suzaku

NASA Technical Reports Server (NTRS)

Smith, Randall K.; Mushotzky, Richard; Kallman, Tim; Tueller, Jack; Mukai, Koji; Markwardt, Craig

2007-01-01

We observed with Suzaku the symbiotic star SS73 17, motivated by the discovery by the INTEGRAL satellite and the Swift BAT survey that it emits hard X-rays. Our observations showed a highly-absorbed X-ray spectrum with NH > loz3 emp2, equivalent to Av > 26, although the source has B magnitude 11.3 and is also bright in UV. The source also shows strong, narrow iron lines including fluorescent Fe K as well as Fe xxv and Fe XXVI. The X-ray spectrum can be fit with a thermal model including an absorption component that partially covers the source. Most of the equivalent width of the iron fluorescent line in this model can be explained as a combination of reprocessing in a dense absorber plus reflection off a white dwarf surface, but it is likely that the continuum is partially seen in reflection as well. Unlike other symbiotic systems that show hard X-ray emission (CH Cyg, RT Cru, T CrB, GX1+4), SS73 17 is not known to have shown nova-like optical variability, X-ray flashes, or pulsations, and has always shown faint soft X-ray emission. As a result, although it is likely a white dwarf, the nature of the compact object in SS73 17 is still uncertain. SS73 17 is probably an extreme example of the recently discovered and relatively small class of hard X-ray emitting symbiotic systems.

Electrochemical method of controlling thiolate coverage on a conductive substrate such as gold

DOEpatents

Porter, M.D.; Weisshaar, D.E.

1998-10-27

An electrochemical method is described for forming a partial monomolecular layer of a predetermined extent of coverage of a thiolate of the formula, XRS-, therein R can be a linear or branched chain hydrocarbon or an aromatic or the like and X can be any compatible end group, e.g., OH, COOH, CH{sub 3} or the like, upon a substrate such as gold, which involves applying in an electrochemical system a constant voltage preselected to yield the desired predetermined extent of coverage. 13 figs.

Robust Economic Control Decision Method of Uncertain System on Urban Domestic Water Supply.

PubMed

Li, Kebai; Ma, Tianyi; Wei, Guo

2018-03-31

As China quickly urbanizes, urban domestic water generally presents the circumstances of both rising tendency and seasonal cycle fluctuation. A robust economic control decision method for dynamic uncertain systems is proposed in this paper. It is developed based on the internal model principle and pole allocation method, and it is applied to an urban domestic water supply system with rising tendency and seasonal cycle fluctuation. To achieve this goal, first a multiplicative model is used to describe the urban domestic water demand. Then, a capital stock and a labor stock are selected as the state vector, and the investment and labor are designed as the control vector. Next, the compensator subsystem is devised in light of the internal model principle. Finally, by using the state feedback control strategy and pole allocation method, the multivariable robust economic control decision method is implemented. The implementation with this model can accomplish the urban domestic water supply control goal, with the robustness for the variation of parameters. The methodology presented in this study may be applied to the water management system in other parts of the world, provided all data used in this study are available. The robust control decision method in this paper is also applicable to deal with tracking control problems as well as stabilization control problems of other general dynamic uncertain systems.

Robust Economic Control Decision Method of Uncertain System on Urban Domestic Water Supply

PubMed Central

Li, Kebai; Ma, Tianyi; Wei, Guo

2018-01-01

As China quickly urbanizes, urban domestic water generally presents the circumstances of both rising tendency and seasonal cycle fluctuation. A robust economic control decision method for dynamic uncertain systems is proposed in this paper. It is developed based on the internal model principle and pole allocation method, and it is applied to an urban domestic water supply system with rising tendency and seasonal cycle fluctuation. To achieve this goal, first a multiplicative model is used to describe the urban domestic water demand. Then, a capital stock and a labor stock are selected as the state vector, and the investment and labor are designed as the control vector. Next, the compensator subsystem is devised in light of the internal model principle. Finally, by using the state feedback control strategy and pole allocation method, the multivariable robust economic control decision method is implemented. The implementation with this model can accomplish the urban domestic water supply control goal, with the robustness for the variation of parameters. The methodology presented in this study may be applied to the water management system in other parts of the world, provided all data used in this study are available. The robust control decision method in this paper is also applicable to deal with tracking control problems as well as stabilization control problems of other general dynamic uncertain systems. PMID:29614749

Communicating uncertainty to agricultural scientists and professionals

NASA Astrophysics Data System (ADS)

Milne, Alice; Glendining, Margaret; Perryman, Sarah; Gordon, Taylor; Whitmore, Andrew

2016-04-01

Models of agricultural systems often aim to predict the impacts of weather and soil nutrients on crop yields and the environment. These models are used to inform scientists, policy makers and farmers on the likely effects of management. For example, a farmer might be interested in the effect of nitrogen fertilizer on his yield, whilst policy makers might be concerned with the possible polluting effects of fertilizer. There are of course uncertainties related to any model predictions and these must be communicated effectively if the end user is to draw proper conclusions and so make sound decisions. We searched the literature and found several methods for expressing the uncertainty in the predictions produced by models. We tested six of these in a formal trial. The methods we considered were: calibrated phrases, such as 'very uncertain' and 'likely', similar to those used by the IPCC; probabilities that the true value of the uncertain quantity lay within a defined range of values; confidence intervals for the expected value; histograms; box plots; and shaded arrays that depict the probability density of the uncertain quantity. We held a series of three workshops at which the participants were invited to assess the six different methods of communicating the uncertainty. In total 64 individuals took part in our study. These individuals were either scientists, policy makers or those who worked in the agricultural industry. The test material comprised four sets of results from models. These results were displayed using each of the six methods described above. The participants were asked to evaluate the methods by filling in a questionnaire. The questions were intended to test how straightforward the content was to interpret and whether each method displayed sufficient information. Our results showed differences in the efficacy of the methods of communication, and interactions with the nature of the target audience. We found that, although the verbal scale was thought to be a good method of communication it did not convey enough information and was open to misinterpretation. Shaded arrays were similarly open to misinterpretation, but proved to give the best impression of uncertainty when individuals were asked to interpret results from the models. Box plots were most favoured by those who had a stronger mathematical background. We propose a combination of methods should be used to convey uncertainty in emissions and that this combination should be tailored to the professional group.

Communicating uncertainty to agricultural scientists and professionals

NASA Astrophysics Data System (ADS)

Milne, Alice; Glendining, Margaret; Perryman, Sarah; Whitmore, Andy

2015-04-01

Models of agricultural systems often aim to predict the impacts of weather and soil nutrients on crop yields and the environment. These models are used to inform scientists, policy makers and farmers on the likely effects of management. For example, a farmer might be interested in the effect of nitrogen fertilizer on his yield, whilst policy makers might be concerned with the possible polluting effects of fertilizer. There are of course uncertainties related to any model predictions and these must be communicated effectively if the end user is to draw proper conclusions and so make sound decisions. We searched the literature and found several methods for expressing the uncertainty in the predictions produced by models. We tested six of these in a formal trial. The methods we considered were: calibrated phrases, such as 'very uncertain' and 'likely', similar to those used by the IPCC; probabilities that the true value of the uncertain quantity lay within a defined range of values; confidence intervals for the expected value; histograms; box plots; and shaded arrays that depict the probability density of the uncertain quantity. We held a series of three workshops at which the participants were invited to assess the six different methods of communicating the uncertainty. In total 64 individuals took part in our study. These individuals were either scientists, policy makers or those who worked in the agricultural industry. The test material comprised four sets of results from models. These results were displayed using each of the six methods described above. The participants were asked to evaluate the methods by filling in a questionnaire. The questions were intended to test how straightforward the content was to interpret and whether each method displayed sufficient information. Our results showed differences in the efficacy of the methods of communication, and interactions with the nature of the target audience. We found that, although the verbal scale was thought to be a good method of communication it did not convey enough information and was open to misinterpretation. Shaded arrays were similarly open to misinterpretation, but proved to give the best impression of uncertainty when individuals were asked to interpret results from the models. Box plots were most favoured by those who had a stronger mathematical background. We propose a combination of methods should be used to convey uncertainty in emissions and that this combination should be tailored to the professional group.

A rare polyglycine type II-like helix motif in naturally occurring proteins.

PubMed

Warkentin, Eberhard; Weidenweber, Sina; Schühle, Karola; Demmer, Ulrike; Heider, Johann; Ermler, Ulrich

2017-11-01

Common structural elements in proteins such as α-helices or β-sheets are characterized by uniformly repeating, energetically favorable main chain conformations which additionally exhibit a completely saturated hydrogen-bonding network of the main chain NH and CO groups. Although polyproline or polyglycine type II helices (PP II or PG II ) are frequently found in proteins, they are not considered as equivalent secondary structure elements because they do not form a similar self-contained hydrogen-bonding network of the main chain atoms. In this context our finding of an unusual motif of glycine-rich PG II -like helices in the structure of the acetophenone carboxylase core complex is of relevance. These PG II -like helices form hexagonal bundles which appear to fulfill the criterion of a (largely) saturated hydrogen-bonding network of the main-chain groups and therefore may be regarded in this sense as a new secondary structure element. It consists of a central PG II -like helix surrounded by six nearly parallel PG II -like helices in a hexagonal array, plus an additional PG II -like helix extending the array outwards. Very related structural elements have previously been found in synthetic polyglycine fibers. In both cases, all main chain NH and CO groups of the central PG II -helix are saturated by either intra- or intermolecular hydrogen-bonds, resulting in a self-contained hydrogen-bonding network. Similar, but incomplete PG II -helix patterns were also previously identified in a GTP-binding protein and an antifreeze protein. © 2017 Wiley Periodicals, Inc.

Analysing stratified medicine business models and value systems: innovation-regulation interactions.

PubMed

Mittra, James; Tait, Joyce

2012-09-15

Stratified medicine offers both opportunities and challenges to the conventional business models that drive pharmaceutical R&D. Given the increasingly unsustainable blockbuster model of drug development, due in part to maturing product pipelines, alongside increasing demands from regulators, healthcare providers and patients for higher standards of safety, efficacy and cost-effectiveness of new therapies, stratified medicine promises a range of benefits to pharmaceutical and diagnostic firms as well as healthcare providers and patients. However, the transition from 'blockbusters' to what might now be termed 'niche-busters' will require the adoption of new, innovative business models, the identification of different and perhaps novel types of value along the R&D pathway, and a smarter approach to regulation to facilitate innovation in this area. In this paper we apply the Innogen Centre's interdisciplinary ALSIS methodology, which we have developed for the analysis of life science innovation systems in contexts where the value creation process is lengthy, expensive and highly uncertain, to this emerging field of stratified medicine. In doing so, we consider the complex collaboration, timing, coordination and regulatory interactions that shape business models, value chains and value systems relevant to stratified medicine. More specifically, we explore in some depth two convergence models for co-development of a therapy and diagnostic before market authorisation, highlighting the regulatory requirements and policy initiatives within the broader value system environment that have a key role in determining the probable success and sustainability of these models. Copyright © 2012 Elsevier B.V. All rights reserved.

Parametric optimal control of uncertain systems under an optimistic value criterion

NASA Astrophysics Data System (ADS)

Li, Bo; Zhu, Yuanguo

2018-01-01

It is well known that the optimal control of a linear quadratic model is characterized by the solution of a Riccati differential equation. In many cases, the corresponding Riccati differential equation cannot be solved exactly such that the optimal feedback control may be a complex time-oriented function. In this article, a parametric optimal control problem of an uncertain linear quadratic model under an optimistic value criterion is considered for simplifying the expression of optimal control. Based on the equation of optimality for the uncertain optimal control problem, an approximation method is presented to solve it. As an application, a two-spool turbofan engine optimal control problem is given to show the utility of the proposed model and the efficiency of the presented approximation method.

Tsallis’ non-extensive free energy as a subjective value of an uncertain reward

NASA Astrophysics Data System (ADS)

Takahashi, Taiki

2009-03-01

Recent studies in neuroeconomics and econophysics revealed the importance of reward expectation in decision under uncertainty. Behavioral neuroeconomic studies have proposed that the unpredictability and the probability of an uncertain reward are distinctly encoded as entropy and a distorted probability weight, respectively, in the separate neural systems. However, previous behavioral economic and decision-theoretic models could not quantify reward-seeking and uncertainty aversion in a theoretically consistent manner. In this paper, we have: (i) proposed that generalized Helmholtz free energy in Tsallis’ non-extensive thermostatistics can be utilized to quantify a perceived value of an uncertain reward, and (ii) empirically examined the explanatory powers of the models. Future study directions in neuroeconomics and econophysics by utilizing the Tsallis’ free energy model are discussed.

Inventory transparency for agricultural produce through IOT

NASA Astrophysics Data System (ADS)

Srinivasan, S. P.; Sorna Shanthi, D.; Anand, Aashish V.

2017-06-01

Re-structuring the practices of traditional inventory management is becoming more essential to optimize the supply chain transparency and accuracy of agricultural produce. A flexible and transparent inventory management system is becoming the need of any agricultural commodity. It was noticed that the major setback for the farmers who are the suppliers of the farm produce is due to poor supply chain integration. The recent advent technologies and IT explosion can bring up a greater impact in the process of storing, tracking, distributing and monitoring perishable agriculture produce of day to day life. The primary focus of this paper is to integrate IoT into inventory management and other inbound logistics management of agriculture produce. The unique features of agricultural produce like a prediction of supply, demand, the location of warehouses, distribution and tracking of inventory can be integrated through IoT. This paper proposes a conceptual framework for inventory management transparency involved in the supply chain of agriculture produce.

The effects of policy actions to improve population dietary patterns and prevent diet-related non-communicable diseases: scoping review

PubMed Central

Hyseni, L; Atkinson, M; Bromley, H; Orton, L; Lloyd-Williams, F; McGill, R; Capewell, S

2017-01-01

Poor diet generates a bigger non-communicable disease (NCD) burden than tobacco, alcohol and physical inactivity combined. We reviewed the potential effectiveness of policy actions to improve healthy food consumption and thus prevent NCDs. This scoping review focused on systematic and non-systematic reviews and categorised data using a seven-part framework: price, promotion, provision, composition, labelling, supply chain, trade/investment and multi-component interventions. We screened 1805 candidate publications and included 58 systematic and non-systematic reviews. Multi-component and price interventions appeared consistently powerful in improving healthy eating. Reformulation to reduce industrial trans fat intake also seemed very effective. Evidence on food supply chain, trade and investment studies was limited and merits further research. Food labelling and restrictions on provision or marketing of unhealthy foods were generally less effective with uncertain sustainability. Increasingly strong evidence is highlighting potentially powerful policies to improve diet and thus prevent NCDs, notably multi-component interventions, taxes, subsidies, elimination and perhaps trade agreements. The implications for policy makers are becoming clearer. PMID:27901036

A production planning model considering uncertain demand using two-stage stochastic programming in a fresh vegetable supply chain context.

PubMed

Mateo, Jordi; Pla, Lluis M; Solsona, Francesc; Pagès, Adela

2016-01-01

Production planning models are achieving more interest for being used in the primary sector of the economy. The proposed model relies on the formulation of a location model representing a set of farms susceptible of being selected by a grocery shop brand to supply local fresh products under seasonal contracts. The main aim is to minimize overall procurement costs and meet future demand. This kind of problem is rather common in fresh vegetable supply chains where producers are located in proximity either to processing plants or retailers. The proposed two-stage stochastic model determines which suppliers should be selected for production contracts to ensure high quality products and minimal time from farm-to-table. Moreover, Lagrangian relaxation and parallel computing algorithms are proposed to solve these instances efficiently in a reasonable computational time. The results obtained show computational gains from our algorithmic proposals in front of the usage of plain CPLEX solver. Furthermore, the results ensure the competitive advantages of using the proposed model by purchase managers in the fresh vegetables industry.

The effects of policy actions to improve population dietary patterns and prevent diet-related non-communicable diseases: scoping review.

PubMed

Hyseni, L; Atkinson, M; Bromley, H; Orton, L; Lloyd-Williams, F; McGill, R; Capewell, S

2017-06-01

Poor diet generates a bigger non-communicable disease (NCD) burden than tobacco, alcohol and physical inactivity combined. We reviewed the potential effectiveness of policy actions to improve healthy food consumption and thus prevent NCDs. This scoping review focused on systematic and non-systematic reviews and categorised data using a seven-part framework: price, promotion, provision, composition, labelling, supply chain, trade/investment and multi-component interventions. We screened 1805 candidate publications and included 58 systematic and non-systematic reviews. Multi-component and price interventions appeared consistently powerful in improving healthy eating. Reformulation to reduce industrial trans fat intake also seemed very effective. Evidence on food supply chain, trade and investment studies was limited and merits further research. Food labelling and restrictions on provision or marketing of unhealthy foods were generally less effective with uncertain sustainability. Increasingly strong evidence is highlighting potentially powerful policies to improve diet and thus prevent NCDs, notably multi-component interventions, taxes, subsidies, elimination and perhaps trade agreements. The implications for policy makers are becoming clearer.

Confined polyelectrolytes: The complexity of a simple system.

PubMed

Nunes, Sandra C C; Skepö, Marie; Pais, Alberto A C C

2015-08-05

The interaction between polyelectrolytes and counterions in confined situations and the mutual relationship between chain conformation and ion condensation is an important issue in several areas. In the biological field, it assumes particular relevance in the understanding of the packaging of nucleic acids, which is crucial in the design of gene delivery systems. In this work, a simple coarse-grained model is used to assess the cooperativity between conformational change and ion condensation in spherically confined backbones, with capsides permeable to the counterions. It is seen that the variation on the degree of condensation depends on counterion valence. For monovalent counterions, the degree of condensation passes through a minimum before increasing as the confining space diminishes. In contrast, for trivalent ions, the overall tendency is to decrease the degree of condensation as the confinement space also decreases. Most of the particles reside close to the spherical wall, even for systems in which the density is higher closer to the cavity center. This effect is more pronounced, when monovalent counterions are present. Additionally, there are clear variations in the charge along the concentric layers that cannot be totally ascribed to polyelectrolyte behavior, as shown by decoupling the chain into monomers. If both chain and counterions are confined, the formation of a counterion rich region immediately before the wall is observed. Spool and doughnut-like structures are formed for stiff chains, within a nontrivial evolution with increasing confinement. © 2015 Wiley Periodicals, Inc.

Estimating the costs of the vaccine supply chain and service delivery for selected districts in Kenya and Tanzania.

PubMed

Mvundura, Mercy; Lorenson, Kristina; Chweya, Amos; Kigadye, Rosemary; Bartholomew, Kathryn; Makame, Mohammed; Lennon, T Patrick; Mwangi, Steven; Kirika, Lydia; Kamau, Peter; Otieno, Abner; Murunga, Peninah; Omurwa, Tom; Dafrossa, Lyimo; Kristensen, Debra

2015-05-28

Having data on the costs of the immunization system can provide decision-makers with information to benchmark the costs when evaluating the impact of new technologies or programmatic innovations. This paper estimated the supply chain and immunization service delivery costs and cost per dose in selected districts in Kenya and Tanzania. We also present operational data describing the supply chain and service delivery points (SDPs). To estimate the supply chain costs, we collected resource-use data for the cold chain, distribution system, and health worker time and per diems paid. We also estimated the service delivery costs, which included the time cost of health workers to provide immunization services, and per diems and transport costs for outreach sessions. Data on the annual quantities of vaccines distributed to each facility, and the occurrence and duration of stockouts were collected from stock registers. These data were collected from the national store, 2 regional and 4 district stores, and 12 SDPs in each country for 2012. Cost per dose for the supply chain and immunization service delivery were estimated. The average annual costs per dose at the SDPs were $0.34 (standard deviation (s.d.) $0.18) for Kenya when including only the vaccine supply chain costs, and $1.33 (s.d. $0.82) when including immunization service delivery costs. In Tanzania, these costs were $0.67 (s.d. $0.35) and $2.82 (s.d. $1.64), respectively. Both countries experienced vaccine stockouts in 2012, bacillus Calmette-Guérin vaccine being more likely to be stocked out in Kenya, and oral poliovirus vaccine in Tanzania. When stockouts happened, they usually lasted for at least one month. Tanzania made investments in 2011 in preparation for planned vaccine introductions, and their supply chain cost per dose is expected to decline with the new vaccine introductions. Immunization service delivery costs are a significant portion of the total costs at the SDPs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enforcing Ising-like magnetic anisotropy via trigonal distortion in the design of a W( v )–Co( ii ) cyanide single-chain magnet

DOE PAGES

Zhang, Yuan-Zhu; Dolinar, Brian S.; Liu, Shihao; ...

2018-01-01

A new octacyanotungstate( v ) singe chain magnet with an effective energy barrier of 39.7(3) cm −1 is achieved by enforcing Ising-like magnetic anisotropy via introduction of trigonal distortion with a fac -tridentate capping ligand.

Enforcing Ising-like magnetic anisotropy via trigonal distortion in the design of a W( v )–Co( ii ) cyanide single-chain magnet

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

Zhang, Yuan-Zhu; Dolinar, Brian S.; Liu, Shihao

A new octacyanotungstate( v ) singe chain magnet with an effective energy barrier of 39.7(3) cm −1 is achieved by enforcing Ising-like magnetic anisotropy via introduction of trigonal distortion with a fac -tridentate capping ligand.

A Taste of Spanish, Foreign Language: 7503.21.

ERIC Educational Resources Information Center

Dade County Public Schools, Miami, FL.

This introductory conversational course is intended for the student who would like to learn some Spanish but is uncertain about his desire to continue its formal study. The course content includes greetings, numbers 0-100, days of the week, months of the year, weather, time, and family, colors, games, dances and songs, and sufficient grammar to…

How Children and Adults Produce and Perceive Uncertainty in Audiovisual Speech

ERIC Educational Resources Information Center

Krahmer, Emiel; Swerts, Marc

2005-01-01

We describe two experiments on signaling and detecting uncertainty in audiovisual speech by adults and children. In the first study, utterances from adult speakers and child speakers (aged 7-8) were elicited and annotated with a set of six audiovisual features. It was found that when adult speakers were uncertain they were more likely to produce…

"Let's Spend More Time Together Like This!": Fussy Baby Network® Infusion in a Baltimore Homeless Nursery Program

ERIC Educational Resources Information Center

Cosgrove, Kim; Norris-Shortle, Carole

2015-01-01

The development of babies whose families are homeless can easily be affected by their uncertain living arrangements. The PACT Therapeutic Nursery's attachment-based, trauma-informed, mindfully focused family interventions help these children and families move beyond the trauma of shelter living. In the past year, Nursery clinicians have infused…

Synthesis and structures of ligand-dominated one-dimensional silver(I)–bis(pyridylmethyl)amine coordination chains

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

Lin, Hung-Jui; Liu, Yu-Chiao; Tseng, Yu-Jui

2016-10-15

Reactants slow diffusion of Ag(I) salts with 3,4′-bis(pyridylmethyl)amine (3,4′-bpma), an unsymmetric bis-pyridyl ligand equipped with a non-innocent amine backbone, afforded polymeric coordination adducts 1–5 having a general formula ([Ag(3,4′-bpma)(solv)]X){sub n} (solv = H{sub 2}O, CH{sub 3}OH, and none; X= CF{sub 3}CO{sub 2}{sup –}, BF{sub 4}{sup –}, ClO{sub 4}{sup –}, CF{sub 3}SO{sub 3}{sup –}, and SbF{sub 6}{sup –}). Single-crystal X-ray diffraction (SCXRD) analyses reveal that colorless crystals of Ag(I) coordination polymers (CPs) 1–5 have very similar one-dimensional (1D) non-flat chain structures, which are preferentially depicted as a “zipper-like” rather than a ladder-like or a double-stranded chain topologies. The 3,4′-bpma ligand inmore » these Ag(I) CPs displays a μ{sub 3}-bridging mode with a gauche–trans (1,4, and 5) and a trans–trans (2 and 3) conformations. Noteworthy, anions do not show strong influence on structural modulation of Ag(I) CPs in the solid state, but really affect CP conformations and packing fashions, indicative of a ligand-dominated assembly process for such a Ag(I)–3,4′-bpma system. Thermal stabilities and solid-state photoluminescence properties of crystalline materials 1–5 were investigated. - Graphical abstract: This work has addressed five ligand-dominated Ag(I)–3,4′-bpma polymeric adducts, which show similar one-dimensional non-flat chain structures depicting a “zipper-like” topology rather than a ladder-like or a double-stranded chain structures.« less

ECERIFERUM2-LIKE proteins have unique biochemical and physiological functions in very-long-chain fatty acid elongation.

PubMed

Haslam, Tegan M; Haslam, Richard; Thoraval, Didier; Pascal, Stéphanie; Delude, Camille; Domergue, Frédéric; Fernández, Aurora Mañas; Beaudoin, Frédéric; Napier, Johnathan A; Kunst, Ljerka; Joubès, Jérôme

2015-03-01

The extension of very-long-chain fatty acids (VLCFAs) for the synthesis of specialized apoplastic lipids requires unique biochemical machinery. Condensing enzymes catalyze the first reaction in fatty acid elongation and determine the chain length of fatty acids accepted and produced by the fatty acid elongation complex. Although necessary for the elongation of all VLCFAs, known condensing enzymes cannot efficiently synthesize VLCFAs longer than 28 carbons, despite the prevalence of C28 to C34 acyl lipids in cuticular wax and the pollen coat. The eceriferum2 (cer2) mutant of Arabidopsis (Arabidopsis thaliana) was previously shown to have a specific deficiency in cuticular waxes longer than 28 carbons, and heterologous expression of CER2 in yeast (Saccharomyces cerevisiae) demonstrated that it can modify the acyl chain length produced by a condensing enzyme from 28 to 30 carbon atoms. Here, we report the physiological functions and biochemical specificities of the CER2 homologs CER2-LIKE1 and CER2-LIKE2 by mutant analysis and heterologous expression in yeast. We demonstrate that all three CER2-LIKEs function with the same small subset of condensing enzymes, and that they have different effects on the substrate specificity of the same condensing enzyme. Finally, we show that the changes in acyl chain length caused by each CER2-LIKE protein are of substantial importance for cuticle formation and pollen coat function. © 2015 American Society of Plant Biologists. All Rights Reserved.

ECERIFERUM2-LIKE Proteins Have Unique Biochemical and Physiological Functions in Very-Long-Chain Fatty Acid Elongation1[OPEN

PubMed Central

Haslam, Tegan M.; Haslam, Richard; Thoraval, Didier; Pascal, Stéphanie; Delude, Camille; Domergue, Frédéric; Fernández, Aurora Mañas; Beaudoin, Frédéric; Napier, Johnathan A.; Kunst, Ljerka; Joubès, Jérôme

2015-01-01

The extension of very-long-chain fatty acids (VLCFAs) for the synthesis of specialized apoplastic lipids requires unique biochemical machinery. Condensing enzymes catalyze the first reaction in fatty acid elongation and determine the chain length of fatty acids accepted and produced by the fatty acid elongation complex. Although necessary for the elongation of all VLCFAs, known condensing enzymes cannot efficiently synthesize VLCFAs longer than 28 carbons, despite the prevalence of C28 to C34 acyl lipids in cuticular wax and the pollen coat. The eceriferum2 (cer2) mutant of Arabidopsis (Arabidopsis thaliana) was previously shown to have a specific deficiency in cuticular waxes longer than 28 carbons, and heterologous expression of CER2 in yeast (Saccharomyces cerevisiae) demonstrated that it can modify the acyl chain length produced by a condensing enzyme from 28 to 30 carbon atoms. Here, we report the physiological functions and biochemical specificities of the CER2 homologs CER2-LIKE1 and CER2-LIKE2 by mutant analysis and heterologous expression in yeast. We demonstrate that all three CER2-LIKEs function with the same small subset of condensing enzymes, and that they have different effects on the substrate specificity of the same condensing enzyme. Finally, we show that the changes in acyl chain length caused by each CER2-LIKE protein are of substantial importance for cuticle formation and pollen coat function. PMID:25596184

Molecular Simulation Studies of Covalently and Ionically Grafted Nanoparticles

NASA Astrophysics Data System (ADS)

Hong, Bingbing

Solvent-free covalently- or ionically-grafted nanoparticles (CGNs and IGNs) are a new class of organic-inorganic hybrid composite materials exhibiting fluid-like behaviors around room temperature. With similar structures to prior systems, e.g. nanocomposites, neutral or charged colloids, ionic liquids, etc, CGNs and IGNs inherit the functionality of inorganic nanopariticles, the facile processibility of polymers, as well as conductivity and nonvolatility from their constituent materials. In spite of the extensive prior experimental research having covered synthesis and measurements of thermal and dynamic properties, little progress in understanding of these new materials at the molecular level has been achieved, because of the lack of simulation work in this new area. Atomistic and coarse-grained molecular dynamics simulations have been performed in this thesis to investigate the thermodynamics, structure, and dynamics of these systems and to seek predictive methods predictable for their properties. Starting from poly(ethylene oxide) oligomers (PEO) melts, we established atomistic models based on united-atom representations of methylene. The Green-Kubo and Einstein-Helfand formulas were used to calculate the transport properties. The simulations generate densities, viscosities, diffusivities, in good agreement with experimental data. The chain-length dependence of the transport properties suggests that neither Rouse nor reptation models are applicable in the short-chain regime investigated. Coupled with thermodynamic integration methods, the models give good predictions of pressure-composition-density relations for CO 2 + PEO oligomers. Water effects on the Henry's constant of CO 2 in PEO have also been investigated. The dependence of the calculated Henry's constants on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length. CGNs are modeled by the inclusion of solid-sphere nanoparticles into the atomistic oligomers. The calculated viscosities from Green-Kubo relationships and temperature extrapolation are of the same order of magnitude as experimental values, but show a smaller activation energy relative to real CGNs systems. Grafted systems have higher viscosities, smaller diffusion coefficients, and slower chain dynamics than the ungrafted counterparts - nanocomposites - at high temperatures. At lower temperatures, grafted systems exhibit faster dynamics for both nanoparticles and chains relative to ungrafted systems, because of lower aggregation of nanoparticles and enhanced correlations between nanoparticles and chains. This agrees with the experimental observation that the new materials have liquid-like behavior in the absence of a solvent. To lower the simulated temperatures into the experimental range, we established a coarse-grained CGNs model by matching structural distribution functions to atomistic simulation data. In contrast with linear polymer systems, for which coarse-graining always accelerate dynamics, coarse-graining of grafted nanoparticles can either accelerate or slowdown the core motions, depending on the length of the grafted chains. This can be qualitatively predicted by a simple transition-state theory. Similar atomistic models to CGNs were developed for IGNs, with ammonium counterions described by an explicit-hydrogen way; these were in turn compared with "generic" coarse-grained IGNs. The elimination of chemical details in the coarse-grained models does not bring in qualitative changes to the radial distribution functions and diffusion of atomistic IGNs, but saves considerable simulation resources and make simulations near room temperatures affordable. The chain counterions in both atomistic and coarse-grained models are mobile, moving from site to site and from nanoparticle to nanoparticle. At the same temperature and the same core volume fractions, the nanoparticle diffusivities in coarse-grained IGNs are slower by a factor ten than the cores of CGNs. The coarse-grained IGNs models are later used to investigate the system dynamics through analysis of the dependence on temperature and structural parameters of the transport properties (self-diffusion coefficients, viscosities and conductivities). Further, migration kinetics of oligomeric counterions is analyzed in a manner analogous to unimer exchange between micellar aggregates. The counterion migrations follow the "double-core" mechanism and are kinetically controlled by neighboring-core collisions. (Abstract shortened by UMI.)

Bayesian multiple-source localization in an uncertain ocean environment.

PubMed

Dosso, Stan E; Wilmut, Michael J

2011-06-01

This paper considers simultaneous localization of multiple acoustic sources when properties of the ocean environment (water column and seabed) are poorly known. A Bayesian formulation is developed in which the environmental parameters, noise statistics, and locations and complex strengths (amplitudes and phases) of multiple sources are considered to be unknown random variables constrained by acoustic data and prior information. Two approaches are considered for estimating source parameters. Focalization maximizes the posterior probability density (PPD) over all parameters using adaptive hybrid optimization. Marginalization integrates the PPD using efficient Markov-chain Monte Carlo methods to produce joint marginal probability distributions for source ranges and depths, from which source locations are obtained. This approach also provides quantitative uncertainty analysis for all parameters, which can aid in understanding of the inverse problem and may be of practical interest (e.g., source-strength probability distributions). In both approaches, closed-form maximum-likelihood expressions for source strengths and noise variance at each frequency allow these parameters to be sampled implicitly, substantially reducing the dimensionality and difficulty of the inversion. Examples are presented of both approaches applied to single- and multi-frequency localization of multiple sources in an uncertain shallow-water environment, and a Monte Carlo performance evaluation study is carried out. © 2011 Acoustical Society of America

Molecular and Culture-Based Bronchoalveolar Lavage Fluid Testing for the Diagnosis of Cytomegalovirus Pneumonitis.

PubMed

Tan, Susanna K; Burgener, Elizabeth B; Waggoner, Jesse J; Gajurel, Kiran; Gonzalez, Sarah; Chen, Sharon F; Pinsky, Benjamin A

2016-01-01

Background.  Cytomegalovirus (CMV) is a major cause of morbidity and mortality in immunocompromised patients, with CMV pneumonitis among the most severe manifestations of infection. Although bronchoalveolar lavage (BAL) samples are frequently tested for CMV, the clinical utility of such testing remains uncertain. Methods.  Retrospective analysis of adult patients undergoing BAL testing via CMV polymerase chain reaction (PCR), shell vial culture, and conventional viral culture between August 2008 and May 2011 was performed. Cytomegalovirus diagnostic methods were compared with a comprehensive definition of CMV pneumonitis that takes into account signs and symptoms, underlying host immunodeficiency, radiographic findings, and laboratory results. Results.  Seven hundred five patients underwent 1077 bronchoscopy episodes with 1090 BAL specimens sent for CMV testing. Cytomegalovirus-positive patients were more likely to be hematopoietic cell transplant recipients (26% vs 8%, P < .0001) and less likely to have an underlying condition not typically associated with lung disease (3% vs 20%, P < .0001). Histopathology was performed in only 17.3% of CMV-positive bronchoscopy episodes. When CMV diagnostic methods were evaluated against the comprehensive definition, the sensitivity and specificity of PCR, shell vial culture, and conventional culture were 91.3% and 94.6%, 54.4% and 97.4%, and 28.3% and 96.5%, respectively. Compared with culture, PCR provided significantly higher sensitivity and negative predictive value (P ≤ .001), without significantly lower positive predictive value. Cytomegalovirus quantitation did not improve test performance, resulting in a receiver operating characteristic curve with an area under the curve of 0.53. Conclusions.  Cytomegalovirus PCR combined with a comprehensive clinical definition provides a pragmatic approach for the diagnosis of CMV pneumonitis.

Laser-induced polarization of a quantum spin system in the steady-state regime

NASA Astrophysics Data System (ADS)

Zvyagin, A. A.

2016-05-01

The effect of the circularly polarized laser field on quantum spin systems in the steady-state regime, in which relaxation plays the central role, has been studied. The dynamical mean-field-like theory predicts several general results for the behavior of the time-average magnetization caused by the laser field. The induced magnetization oscillates with the frequency of the laser field (while Rabi-like oscillations, which modulate the latter in the dynamical regime, are damped by the relaxation in the steady-state regime). At high frequencies, that magnetization is determined by the value to which the relaxation process is directed. At low frequencies the slope of that magnetization as a function of the frequency is determined by the strength of the laser field. The anisotropy determines the resonance behavior of the time-averaged magnetization in both the ferromagnetic and antiferromagnetic cases with nonzero magnetic anisotropy. Nonlinear effects (in the magnitude of the laser field) have been considered. The effect of the laser field on quantum spin systems is maximal in resonance, where the time-averaged magnetization, caused by the laser field, is changed essentially. Out of resonance the changes in the magnetization are relatively small. The resonance effect is caused by the nonzero magnetic anisotropy. The resonance frequency is small (proportional to the anisotropy value) for spin systems with ferromagnetic interactions and enhanced by exchange interactions in the spin systems with antiferromagnetic couplings. We show that it is worthwhile to study the laser-field-induced magnetization of quantum spin systems caused by the high-frequency laser field in the steady-state regime in "easy-axis" antiferromagnetic spin systems (e.g., in Ising-like antiferromagnetic spin-chain materials). The effects of the Dzyaloshinskii-Moriya interaction and the spin-frustration couplings (in the case of the zigzag spin chain) have been analyzed.

Optimal second order sliding mode control for linear uncertain systems.

PubMed

Das, Madhulika; Mahanta, Chitralekha

2014-11-01

In this paper an optimal second order sliding mode controller (OSOSMC) is proposed to track a linear uncertain system. The optimal controller based on the linear quadratic regulator method is designed for the nominal system. An integral sliding mode controller is combined with the optimal controller to ensure robustness of the linear system which is affected by parametric uncertainties and external disturbances. To achieve finite time convergence of the sliding mode, a nonsingular terminal sliding surface is added with the integral sliding surface giving rise to a second order sliding mode controller. The main advantage of the proposed OSOSMC is that the control input is substantially reduced and it becomes chattering free. Simulation results confirm superiority of the proposed OSOSMC over some existing. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Adaptive sensor-fault tolerant control for a class of multivariable uncertain nonlinear systems.

PubMed

Khebbache, Hicham; Tadjine, Mohamed; Labiod, Salim; Boulkroune, Abdesselem

2015-03-01

This paper deals with the active fault tolerant control (AFTC) problem for a class of multiple-input multiple-output (MIMO) uncertain nonlinear systems subject to sensor faults and external disturbances. The proposed AFTC method can tolerate three additive (bias, drift and loss of accuracy) and one multiplicative (loss of effectiveness) sensor faults. By employing backstepping technique, a novel adaptive backstepping-based AFTC scheme is developed using the fact that sensor faults and system uncertainties (including external disturbances and unexpected nonlinear functions caused by sensor faults) can be on-line estimated and compensated via robust adaptive schemes. The stability analysis of the closed-loop system is rigorously proven using a Lyapunov approach. The effectiveness of the proposed controller is illustrated by two simulation examples. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Observer-Based Adaptive NN Control for a Class of Uncertain Nonlinear Systems With Nonsymmetric Input Saturation.

PubMed

Yong-Feng Gao; Xi-Ming Sun; Changyun Wen; Wei Wang

2017-07-01

This paper is concerned with the problem of adaptive tracking control for a class of uncertain nonlinear systems with nonsymmetric input saturation and immeasurable states. The radial basis function of neural network (NN) is employed to approximate unknown functions, and an NN state observer is designed to estimate the immeasurable states. To analyze the effect of input saturation, an auxiliary system is employed. By the aid of adaptive backstepping technique, an adaptive tracking control approach is developed. Under the proposed adaptive tracking controller, the boundedness of all the signals in the closed-loop system is achieved. Moreover, distinct from most of the existing references, the tracking error can be bounded by an explicit function of design parameters and saturation input error. Finally, an example is given to show the effectiveness of the proposed method.

Climate change induced transformations of agricultural systems: insights from a global model

NASA Astrophysics Data System (ADS)

Leclère, D.; Havlík, P.; Fuss, S.; Schmid, E.; Mosnier, A.; Walsh, B.; Valin, H.; Herrero, M.; Khabarov, N.; Obersteiner, M.

2014-12-01

Climate change might impact crop yields considerably and anticipated transformations of agricultural systems are needed in the coming decades to sustain affordable food provision. However, decision-making on transformational shifts in agricultural systems is plagued by uncertainties concerning the nature and geography of climate change, its impacts, and adequate responses. Locking agricultural systems into inadequate transformations costly to adjust is a significant risk and this acts as an incentive to delay action. It is crucial to gain insight into how much transformation is required from agricultural systems, how robust such strategies are, and how we can defuse the associated challenge for decision-making. While implementing a definition related to large changes in resource use into a global impact assessment modelling framework, we find transformational adaptations to be required of agricultural systems in most regions by 2050s in order to cope with climate change. However, these transformations widely differ across climate change scenarios: uncertainties in large-scale development of irrigation span in all continents from 2030s on, and affect two-thirds of regions by 2050s. Meanwhile, significant but uncertain reduction of major agricultural areas affects the Northern Hemisphere’s temperate latitudes, while increases to non-agricultural zones could be large but uncertain in one-third of regions. To help reducing the associated challenge for decision-making, we propose a methodology exploring which, when, where and why transformations could be required and uncertain, by means of scenario analysis.

Particle filter based hybrid prognostics for health monitoring of uncertain systems in bond graph framework

NASA Astrophysics Data System (ADS)

Jha, Mayank Shekhar; Dauphin-Tanguy, G.; Ould-Bouamama, B.

2016-06-01

The paper's main objective is to address the problem of health monitoring of system parameters in Bond Graph (BG) modeling framework, by exploiting its structural and causal properties. The system in feedback control loop is considered uncertain globally. Parametric uncertainty is modeled in interval form. The system parameter is undergoing degradation (prognostic candidate) and its degradation model is assumed to be known a priori. The detection of degradation commencement is done in a passive manner which involves interval valued robust adaptive thresholds over the nominal part of the uncertain BG-derived interval valued analytical redundancy relations (I-ARRs). The latter forms an efficient diagnostic module. The prognostics problem is cast as joint state-parameter estimation problem, a hybrid prognostic approach, wherein the fault model is constructed by considering the statistical degradation model of the system parameter (prognostic candidate). The observation equation is constructed from nominal part of the I-ARR. Using particle filter (PF) algorithms; the estimation of state of health (state of prognostic candidate) and associated hidden time-varying degradation progression parameters is achieved in probabilistic terms. A simplified variance adaptation scheme is proposed. Associated uncertainties which arise out of noisy measurements, parametric degradation process, environmental conditions etc. are effectively managed by PF. This allows the production of effective predictions of the remaining useful life of the prognostic candidate with suitable confidence bounds. The effectiveness of the novel methodology is demonstrated through simulations and experiments on a mechatronic system.

Project Delivery System Mode Decision Based on Uncertain AHP and Fuzzy Sets

NASA Astrophysics Data System (ADS)

Kaishan, Liu; Huimin, Li

2017-12-01

The project delivery system mode determines the contract pricing type, project management mode and the risk allocation among all participants. Different project delivery system modes have different characteristics and applicable scope. For the owners, the selection of the delivery mode is the key point to decide whether the project can achieve the expected benefits, it relates to the success or failure of project construction. Under the precondition of comprehensively considering the influence factors of the delivery mode, the model of project delivery system mode decision was set up on the basis of uncertain AHP and fuzzy sets, which can well consider the uncertainty and fuzziness when conducting the index evaluation and weight confirmation, so as to rapidly and effectively identify the most suitable delivery mode according to project characteristics. The effectiveness of the model has been verified via the actual case analysis in order to provide reference for the construction project delivery system mode.

Rendezvous with connectivity preservation for multi-robot systems with an unknown leader

NASA Astrophysics Data System (ADS)

Dong, Yi

2018-02-01

This paper studies the leader-following rendezvous problem with connectivity preservation for multi-agent systems composed of uncertain multi-robot systems subject to external disturbances and an unknown leader, both of which are generated by a so-called exosystem with parametric uncertainty. By combining internal model design, potential function technique and adaptive control, two distributed control strategies are proposed to maintain the connectivity of the communication network, to achieve the asymptotic tracking of all the followers to the output of the unknown leader system, as well as to reject unknown external disturbances. It is also worth to mention that the uncertain parameters in the multi-robot systems and exosystem are further allowed to belong to unknown and unbounded sets when applying the second fully distributed control law containing a dynamic gain inspired by high-gain adaptive control or self-tuning regulator.

Fuzzy Adaptive Control Design and Discretization for a Class of Nonlinear Uncertain Systems.

PubMed

Zhao, Xudong; Shi, Peng; Zheng, Xiaolong

2016-06-01

In this paper, tracking control problems are investigated for a class of uncertain nonlinear systems in lower triangular form. First, a state-feedback controller is designed by using adaptive backstepping technique and the universal approximation ability of fuzzy logic systems. During the design procedure, a developed method with less computation is proposed by constructing one maximum adaptive parameter. Furthermore, adaptive controllers with nonsymmetric dead-zone are also designed for the systems. Then, a sampled-data control scheme is presented to discretize the obtained continuous-time controller by using the forward Euler method. It is shown that both proposed continuous and discrete controllers can ensure that the system output tracks the target signal with a small bounded error and the other closed-loop signals remain bounded. Two simulation examples are presented to verify the effectiveness and applicability of the proposed new design techniques.

Cross-talk between branched-chain amino acids and hepatic mitochondria is compromised in nonalcoholic fatty liver disease.

PubMed

Sunny, Nishanth E; Kalavalapalli, Srilaxmi; Bril, Fernando; Garrett, Timothy J; Nautiyal, Manisha; Mathew, Justin T; Williams, Caroline M; Cusi, Kenneth

2015-08-15

Elevated plasma branched-chain amino acids (BCAA) in the setting of insulin resistance have been relevant in predicting type 2 diabetes mellitus (T2DM) onset, but their role in the etiology of hepatic insulin resistance remains uncertain. We determined the link between BCAA and dysfunctional hepatic tricarboxylic acid (TCA) cycle, which is a central feature of hepatic insulin resistance and nonalcoholic fatty liver disease (NAFLD). Plasma metabolites under basal fasting and euglycemic hyperinsulinemic clamps (insulin stimulation) were measured in 94 human subjects with varying degrees of insulin sensitivity to identify their relationships with insulin resistance. Furthermore, the impact of elevated BCAA on hepatic TCA cycle was determined in a diet-induced mouse model of NAFLD, utilizing targeted metabolomics and nuclear magnetic resonance (NMR)-based metabolic flux analysis. Insulin stimulation revealed robust relationships between human plasma BCAA and indices of insulin resistance, indicating chronic metabolic overload from BCAA. Human plasma BCAA and long-chain acylcarnitines also showed a positive correlation, suggesting modulation of mitochondrial metabolism by BCAA. Concurrently, mice with NAFLD failed to optimally induce hepatic mTORC1, plasma ketones, and hepatic long-chain acylcarnitines, following acute elevation of plasma BCAA. Furthermore, elevated BCAA failed to induce multiple fluxes through hepatic TCA cycle in mice with NAFLD. Our data suggest that BCAA are essential to mediate efficient channeling of carbon substrates for oxidation through mitochondrial TCA cycle. Impairment of BCAA-mediated upregulation of the TCA cycle could be a significant contributor to mitochondrial dysfunction in NAFLD.

Cross-talk between branched-chain amino acids and hepatic mitochondria is compromised in nonalcoholic fatty liver disease

PubMed Central

Kalavalapalli, Srilaxmi; Bril, Fernando; Garrett, Timothy J.; Nautiyal, Manisha; Mathew, Justin T.; Williams, Caroline M.; Cusi, Kenneth

2015-01-01

Elevated plasma branched-chain amino acids (BCAA) in the setting of insulin resistance have been relevant in predicting type 2 diabetes mellitus (T2DM) onset, but their role in the etiology of hepatic insulin resistance remains uncertain. We determined the link between BCAA and dysfunctional hepatic tricarboxylic acid (TCA) cycle, which is a central feature of hepatic insulin resistance and nonalcoholic fatty liver disease (NAFLD). Plasma metabolites under basal fasting and euglycemic hyperinsulinemic clamps (insulin stimulation) were measured in 94 human subjects with varying degrees of insulin sensitivity to identify their relationships with insulin resistance. Furthermore, the impact of elevated BCAA on hepatic TCA cycle was determined in a diet-induced mouse model of NAFLD, utilizing targeted metabolomics and nuclear magnetic resonance (NMR)-based metabolic flux analysis. Insulin stimulation revealed robust relationships between human plasma BCAA and indices of insulin resistance, indicating chronic metabolic overload from BCAA. Human plasma BCAA and long-chain acylcarnitines also showed a positive correlation, suggesting modulation of mitochondrial metabolism by BCAA. Concurrently, mice with NAFLD failed to optimally induce hepatic mTORC1, plasma ketones, and hepatic long-chain acylcarnitines, following acute elevation of plasma BCAA. Furthermore, elevated BCAA failed to induce multiple fluxes through hepatic TCA cycle in mice with NAFLD. Our data suggest that BCAA are essential to mediate efficient channeling of carbon substrates for oxidation through mitochondrial TCA cycle. Impairment of BCAA-mediated upregulation of the TCA cycle could be a significant contributor to mitochondrial dysfunction in NAFLD. PMID:26058864

[Strategy of liver resection during chemotherapy for otherwise unresectable colorectal metastases].

PubMed

Tanaka, Kuniya; Kumamoto, Takafumi; Takeda, Kazuhisa; Nojiri, Kazunori; Endo, Itaru

2013-07-01

With multidisciplinary management of patients with effective chemotherapy that can downstage metastases, more patients with previously inoperable disease can benefit from surgery. Surgery in isolation may be approaching technical limits, but now is likely to help more patients because of success of complementary strategies, particularly newer chemotherapy and targeted therapy. Leaving behind disappearing metastases after chemotherapy, margin-positive resection, staged liver resection, and liver-first reversed management permit potentially curative surgery for patients previously unable to survive resection. Further, survival benefit from maximum debulking surgery, like ovarian cancer, for colorectal liver metastases is uncertain at present, but likely. Individualized multidisciplinary treatment planning using such strategies is essential.

Is Geometric Frustration-Induced Disorder a Recipe for High Ionic Conductivity?

PubMed

Düvel, Andre; Heitjans, Paul; Fedorov, Pavel; Scholz, Gudrun; Cibin, Giannantonio; Chadwick, Alan V; Pickup, David M; Ramos, Silvia; Sayle, Lewis W L; Sayle, Emma K L; Sayle, Thi X T; Sayle, Dean C

2017-04-26

Ionic conductivity is ubiquitous to many industrially important applications such as fuel cells, batteries, sensors, and catalysis. Tunable conductivity in these systems is therefore key to their commercial viability. Here, we show that geometric frustration can be exploited as a vehicle for conductivity tuning. In particular, we imposed geometric frustration upon a prototypical system, CaF 2 , by ball milling it with BaF 2 , to create nanostructured Ba 1-x Ca x F 2 solid solutions and increased its ionic conductivity by over 5 orders of magnitude. By mirroring each experiment with MD simulation, including "simulating synthesis", we reveal that geometric frustration confers, on a system at ambient temperature, structural and dynamical attributes that are typically associated with heating a material above its superionic transition temperature. These include structural disorder, excess volume, pseudovacancy arrays, and collective transport mechanisms; we show that the excess volume correlates with ionic conductivity for the Ba 1-x Ca x F 2 system. We also present evidence that geometric frustration-induced conductivity is a general phenomenon, which may help explain the high ionic conductivity in doped fluorite-structured oxides such as ceria and zirconia, with application for solid oxide fuel cells. A review on geometric frustration [ Nature 2015 , 521 , 303 ] remarks that classical crystallography is inadequate to describe systems with correlated disorder, but that correlated disorder has clear crystallographic signatures. Here, we identify two possible crystallographic signatures of geometric frustration: excess volume and correlated "snake-like" ionic transport; the latter infers correlated disorder. In particular, as one ion in the chain moves, all the other (correlated) ions in the chain move simultaneously. Critically, our simulations reveal snake-like chains, over 40 Å in length, which indicates long-range correlation in our disordered systems. Similarly, collective transport in glassy materials is well documented [for example, J. Chem. Phys. 2013 , 138 , 12A538 ]. Possible crystallographic nomenclatures, to be used to describe long-range order in disordered systems, may include, for example, the shape, length, and branching of the "snake" arrays. Such characterizations may ultimately provide insight and differences between long-range order in disordered, amorphous, or liquid states and processes such as ionic conductivity, melting, and crystallization.

Elastin-like Polypeptide Linkers for Single-Molecule Force Spectroscopy.

PubMed

Ott, Wolfgang; Jobst, Markus A; Bauer, Magnus S; Durner, Ellis; Milles, Lukas F; Nash, Michael A; Gaub, Hermann E

2017-06-27

Single-molecule force spectroscopy (SMFS) is by now well established as a standard technique in biophysics and mechanobiology. In recent years, the technique has benefitted greatly from new approaches to bioconjugation of proteins to surfaces. Indeed, optimized immobilization strategies for biomolecules and refined purification schemes are being steadily adapted and improved, which in turn has enhanced data quality. In many previously reported SMFS studies, poly(ethylene glycol) (PEG) was used to anchor molecules of interest to surfaces and/or cantilever tips. The limitation, however, is that PEG exhibits a well-known trans-trans-gauche to all-trans transition, which results in marked deviation from standard polymer elasticity models such as the worm-like chain, particularly at elevated forces. As a result, the assignment of unfolding events to protein domains based on their corresponding amino acid chain lengths is significantly obscured. Here, we provide a solution to this problem by implementing unstructured elastin-like polypeptides as linkers to replace PEG. We investigate the suitability of tailored elastin-like polypeptides linkers and perform direct comparisons to PEG, focusing on attributes that are critical for single-molecule force experiments such as linker length, monodispersity, and bioorthogonal conjugation tags. Our results demonstrate that by avoiding the ambiguous elastic response of mixed PEG/peptide systems and instead building the molecular mechanical systems with only a single bond type with uniform elastic properties, we improve data quality and facilitate data analysis and interpretation in force spectroscopy experiments. The use of all-peptide linkers allows alternative approaches for precisely defining elastic properties of proteins linked to surfaces.

The influence of eastern philosophy on elder care by Chinese Americans: attitudes toward long-term care.

PubMed

Smith, Cary Stacy; Hung, Li-Ching

2012-01-01

Chinese philosophy has been a major cornerstone of Chinese culture for millennia and has bestowed on the world traditions such as Taoism, Yin and Yang, and filial piety. Although these beliefs have remained steadfast over thousands of years, their ability to survive unchanged in the future is uncertain. As the world forges ahead into the 21st century, several pertinent questions arise: Will age-old axioms, primarily those concerning elderly Chinese and their relationship with their children, survive? When ancient, traditional beliefs conflict with newer, Western ideas, which system of thought is likely to be the victor? Moreover, will elderly Chinese Americans and their perceptions concerning long-term care facilities cause problems with the traditional familial unit? This article will discuss these issues in detail.

The Fukushima Nuclear Event and its Implications for Nuclear Power

NASA Astrophysics Data System (ADS)

Golay, Michael

2011-11-01

The combined strong earthquake and super tsunami of 12 March 2011 at the Fukushima nuclear power plant imposed the most severe challenges ever experienced at such a facility. Information regarding the plant response and status remains uncertain, but it is clear that severe damage has been sustained, that the plant staff have responded creatively and that the offsite implications are unlikely to be seriously threatening to the health, if not the prosperity, of the surrounding population. Reexamination of the regulatory constraints of nuclear power will occur worldwide, and some changes are likely; particularly concerning reliance upon active systems for achieving critical safety functions and concerning treatments of used reactor fuel. Whether worldwide expansion of the nuclear power economy will be slowed in the long run is perhaps unlikely and worth discussion.

Climate Change, Foodborne Pathogens and Illness in Higher-Income Countries.

PubMed

Lake, I R; Barker, G C

2018-03-01

We present a review of the likely consequences of climate change for foodborne pathogens and associated human illness in higher-income countries. The relationships between climate and food are complex and hence the impacts of climate change uncertain. This makes it difficult to know which foodborne pathogens will be most affected, what the specific effects will be, and on what timescales changes might occur. Hence, a focus upon current capacity and adaptation potential against foodborne pathogens is essential. We highlight a number of developments that may enhance preparedness for climate change. These include the following: Adoption of novel surveillance methods, such as syndromic methods, to speed up detection and increase the fidelity of intervention in foodborne outbreaks Genotype-based approaches to surveillance of food pathogens to enhance spatiotemporal resolution in tracing and tracking of illness Ever increasing integration of plant, animal and human surveillance systems, One Health, to maximise potential for identifying threats Increased commitment to cross-border (global) information initiatives (including big data) Improved clarity regarding the governance of complex societal issues such as the conflict between food safety and food waste Strong user-centric (social) communications strategies to engage diverse stakeholder groups The impact of climate change upon foodborne pathogens and associated illness is uncertain. This emphasises the need to enhance current capacity and adaptation potential against foodborne illness. A range of developments are explored in this paper to enhance preparedness.

A discrete scattering series representation for lattice embedded models of chain cyclization

NASA Astrophysics Data System (ADS)

Fraser, Simon J.; Winnik, Mitchell A.

1980-01-01

In this paper we develop a lattice based model of chain cyclization in the presence of a set of occupied sites V in the lattice. We show that within the approximation of a Markovian chain propagator the effect of V on the partition function for the system can be written as a time-ordered exponential series in which V behaves like a scattering potential and chainlength is the timelike parameter. The discrete and finite nature of this model allows us to obtain rigorous upper and lower bounds to the series limit. We adapt these formulas to calculation of the partition functions and cyclization probabilities of terminally and globally cyclizing chains. Two classes of cyclization are considered: in the first model the target set H may be visited repeatedly (the Markovian model); in the second case vertices in H may be visited at most once(the non-Markovian or taboo model). This formulation depends on two fundamental combinatorial structures, namely the inclusion-exclusion principle and the set of subsets of a set. We have tried to interpret these abstract structures with physical analogies throughout the paper.

Distinct Tensile Response of Model Semi-flexible Elastomer Networks

NASA Astrophysics Data System (ADS)

Aguilera-Mercado, Bernardo M.; Cohen, Claude; Escobedo, Fernando A.

2011-03-01

Through coarse-grained molecular modeling, we study how the elastic response strongly depends upon nanostructural heterogeneities in model networks made of semi-flexible chains exhibiting both regular and realistic connectivity. Idealized regular polymer networks have been shown to display a peculiar elastic response similar to that of super-tough natural materials (e.g., organic adhesives inside abalone shells). We investigate the impact of chain stiffness, and the effect of including tri-block copolymer chains, on the network's topology and elastic response. We find in some systems a dual tensile response: a liquid-like behavior at small deformations, and a distinct saw-tooth shaped stress-strain curve at moderate to large deformations. Additionally, stiffer regular networks exhibit a marked hysteresis over loading-unloading cycles that can be deleted by heating-cooling cycles or by performing deformations along different axes. Furthermore, small variations of chain stiffness may entirely change the nature of the network's tensile response from an entropic to an enthalpic elastic regime, and micro-phase separation of different blocks within elastomer networks may significantly enhance their mechanical strength. This work was supported by the American Chemical Society.

A Black-Scholes Approach to Satisfying the Demand in a Failure-Prone Manufacturing System

NASA Technical Reports Server (NTRS)

Chavez-Fuentes, Jorge R.; Gonzalex, Oscar R.; Gray, W. Steven

2007-01-01

The goal of this paper is to use a financial model and a hedging strategy in a systems application. In particular, the classical Black-Scholes model, which was developed in 1973 to find the fair price of a financial contract, is adapted to satisfy an uncertain demand in a manufacturing system when one of two production machines is unreliable. This financial model together with a hedging strategy are used to develop a closed formula for the production strategies of each machine. The strategy guarantees that the uncertain demand will be met in probability at the final time of the production process. It is assumed that the production efficiency of the unreliable machine can be modeled as a continuous-time stochastic process. Two simple examples illustrate the result.

Cooperative learning neural network output feedback control of uncertain nonlinear multi-agent systems under directed topologies

NASA Astrophysics Data System (ADS)

Wang, W.; Wang, D.; Peng, Z. H.

2017-09-01

Without assuming that the communication topologies among the neural network (NN) weights are to be undirected and the states of each agent are measurable, the cooperative learning NN output feedback control is addressed for uncertain nonlinear multi-agent systems with identical structures in strict-feedback form. By establishing directed communication topologies among NN weights to share their learned knowledge, NNs with cooperative learning laws are employed to identify the uncertainties. By designing NN-based κ-filter observers to estimate the unmeasurable states, a new cooperative learning output feedback control scheme is proposed to guarantee that the system outputs can track nonidentical reference signals with bounded tracking errors. A simulation example is given to demonstrate the effectiveness of the theoretical results.

Cooperatively surrounding control for multiple Euler-Lagrange systems subjected to uncertain dynamics and input constraints

NASA Astrophysics Data System (ADS)

Chen, Liang-Ming; Lv, Yue-Yong; Li, Chuan-Jiang; Ma, Guang-Fu

2016-12-01

In this paper, we investigate cooperatively surrounding control (CSC) of multi-agent systems modeled by Euler-Lagrange (EL) equations under a directed graph. With the consideration of the uncertain dynamics in an EL system, a backstepping CSC algorithm combined with neural-networks is proposed first such that the agents can move cooperatively to surround the stationary target. Then, a command filtered backstepping CSC algorithm is further proposed to deal with the constraints on control input and the absence of neighbors’ velocity information. Numerical examples of eight satellites surrounding one space target illustrate the effectiveness of the theoretical results. Project supported by the National Basic Research Program of China (Grant No. 2012CB720000) and the National Natural Science Foundation of China (Grant Nos. 61304005 and 61403103).

Robust passive control for a class of uncertain neutral systems based on sliding mode observer.

PubMed

Liu, Zhen; Zhao, Lin; Kao, Yonggui; Gao, Cunchen

2017-01-01

The passivity-based sliding mode control (SMC) problem for a class of uncertain neutral systems with unmeasured states is investigated. Firstly, a particular non-fragile state observer is designed to generate the estimations of the system states, based upon which a novel integral-type sliding surface function is established for the control process. Secondly, a new sufficient condition for robust asymptotic stability and passivity of the resultant sliding mode dynamics (SMDs) is obtained in terms of linear matrix inequalities (LMIs). Thirdly, the finite-time reachability of the predesigned sliding surface is ensured by resorting to a novel adaptive SMC law. Finally, the validity and superiority of the scheme are justified via several examples. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Terminal Sliding Mode-Based Consensus Tracking Control for Networked Uncertain Mechanical Systems on Digraphs.

PubMed

Chen, Gang; Song, Yongduan; Guan, Yanfeng

2018-03-01

This brief investigates the finite-time consensus tracking control problem for networked uncertain mechanical systems on digraphs. A new terminal sliding-mode-based cooperative control scheme is developed to guarantee that the tracking errors converge to an arbitrarily small bound around zero in finite time. All the networked systems can have different dynamics and all the dynamics are unknown. A neural network is used at each node to approximate the local unknown dynamics. The control schemes are implemented in a fully distributed manner. The proposed control method eliminates some limitations in the existing terminal sliding-mode-based consensus control methods and extends the existing analysis methods to the case of directed graphs. Simulation results on networked robot manipulators are provided to show the effectiveness of the proposed control algorithms.

Proteomic Analysis of Acetaminophen-Induced Changes in Mitochondrial Protein Expression Using Spectral Counting

PubMed Central

Stamper, Brendan D.; Mohar, Isaac; Kavanagh, Terrance J.; Nelson, Sidney D.

2011-01-01

Comparative proteomic analysis following treatment with acetaminophen (APAP) was performed on two different models of APAP-mediated hepatocellular injury in order to both identify common targets for adduct formation and track drug-induced changes in protein expression. Male C57BL/6 mice were used as a model for APAP-mediated liver injury in vivo and TAMH cells were used as a model for APAP-mediated cytotoxicity in vitro. SEQUEST was unable to identify the precise location of sites of adduction following treatment with APAP in either system. However, semiquantitative analysis of the proteomic datasets using spectral counting revealed a downregulation of P450 isoforms associated with APAP bioactivation, and an upregulation of proteins related to the electron transport chain by APAP compared to control. Both mechanisms are likely compensatory in nature as decreased P450 expression is likely to attenuate toxicity associated with N-acetyl-p-quinoneimine (NAPQI) formation, whereas APAP-induced electron transport chain component upregulation may be an attempt to promote cellular bioenergetics. PMID:21329376

Influence of chain rigidity on the conformation of model lipid membranes in the presence of cylindrical nanoparticle inclusions

NASA Astrophysics Data System (ADS)

Diloreto, Chris; Wickham, Robert

2012-02-01

We employ real-space self-consistent field theory to study the conformation of model lipid membranes in the presence of solvent and cylindrical nanoparticle inclusions (''peptides''). Whereas it is common to employ a polymeric Gaussian chain model for the lipids, here we model the lipids as persistent, worm-like chains. Our motivation is to develop a more realistic field theory to describe the action of pore-forming anti-microbial peptides that disrupt the bacterial cell membrane. We employ operator-splitting and a pseudo-spectral algorithm, using SpharmonicKit for the chain tangent degrees of freedom, to solve for the worm-like chain propagator. The peptides, modelled using a mask function, have a surface patterned with hydrophobic and hydrophillic patches, but no charge. We examine the role chain rigidity plays in the hydrophobic mismatch, the membrane-mediated interaction between two peptides, the size and structure of pores formed by peptide aggregates, and the free-energy barrier for peptide insertion into the membrane. Our results suggest that chain rigidity influences both the pore structure and the mechanism of pore formation.

Human visual system-based smoking event detection

NASA Astrophysics Data System (ADS)

Odetallah, Amjad D.; Agaian, Sos S.

2012-06-01

Human action (e.g. smoking, eating, and phoning) analysis is an important task in various application domains like video surveillance, video retrieval, human-computer interaction systems, and so on. Smoke detection is a crucial task in many video surveillance applications and could have a great impact to raise the level of safety of urban areas, public parks, airplanes, hospitals, schools and others. The detection task is challenging since there is no prior knowledge about the object's shape, texture and color. In addition, its visual features will change under different lighting and weather conditions. This paper presents a new scheme of a system for detecting human smoking events, or small smoke, in a sequence of images. In developed system, motion detection and background subtraction are combined with motion-region-saving, skin-based image segmentation, and smoke-based image segmentation to capture potential smoke regions which are further analyzed to decide on the occurrence of smoking events. Experimental results show the effectiveness of the proposed approach. As well, the developed method is capable of detecting the small smoking events of uncertain actions with various cigarette sizes, colors, and shapes.

Effect of chain stiffness on the competition between crystallization and glass-formation in model unentangled polymers

NASA Astrophysics Data System (ADS)

Nguyen, Hong T.; Smith, Tyler B.; Hoy, Robert S.; Karayiannis, Nikos Ch.

2015-10-01

We map out the solid-state morphologies formed by model soft-pearl-necklace polymers as a function of chain stiffness, spanning the range from fully flexible to rodlike chains. The ratio of Kuhn length to bead diameter (lK/r0) increases monotonically with increasing bending stiffness kb and yields a one-parameter model that relates chain shape to bulk morphology. In the flexible limit, monomers occupy the sites of close-packed crystallites while chains retain random-walk-like order. In the rodlike limit, nematic chain ordering typical of lamellar precursors coexists with close-packing. At intermediate values of bending stiffness, the competition between random-walk-like and nematic chain ordering produces glass-formation; the range of kb over which this occurs increases with the thermal cooling rate | T ˙ | implemented in our molecular dynamics simulations. Finally, values of kb between the glass-forming and rodlike ranges produce complex ordered phases such as close-packed spirals. Our results should provide a useful initial step in a coarse-grained modeling approach to systematically determining the effect of chain stiffness on the crystallization-vs-glass-formation competition in both synthetic and colloidal polymers.

An imprecise probability approach for squeal instability analysis based on evidence theory

NASA Astrophysics Data System (ADS)

Lü, Hui; Shangguan, Wen-Bin; Yu, Dejie

2017-01-01

An imprecise probability approach based on evidence theory is proposed for squeal instability analysis of uncertain disc brakes in this paper. First, the squeal instability of the finite element (FE) model of a disc brake is investigated and its dominant unstable eigenvalue is detected by running two typical numerical simulations, i.e., complex eigenvalue analysis (CEA) and transient dynamical analysis. Next, the uncertainty mainly caused by contact and friction is taken into account and some key parameters of the brake are described as uncertain parameters. All these uncertain parameters are usually involved with imprecise data such as incomplete information and conflict information. Finally, a squeal instability analysis model considering imprecise uncertainty is established by integrating evidence theory, Taylor expansion, subinterval analysis and surrogate model. In the proposed analysis model, the uncertain parameters with imprecise data are treated as evidence variables, and the belief measure and plausibility measure are employed to evaluate system squeal instability. The effectiveness of the proposed approach is demonstrated by numerical examples and some interesting observations and conclusions are summarized from the analyses and discussions. The proposed approach is generally limited to the squeal problems without too many investigated parameters. It can be considered as a potential method for squeal instability analysis, which will act as the first step to reduce squeal noise of uncertain brakes with imprecise information.

Robust master-slave synchronization for general uncertain delayed dynamical model based on adaptive control scheme.

PubMed

Wang, Tianbo; Zhou, Wuneng; Zhao, Shouwei; Yu, Weiqin

2014-03-01

In this paper, the robust exponential synchronization problem for a class of uncertain delayed master-slave dynamical system is investigated by using the adaptive control method. Different from some existing master-slave models, the considered master-slave system includes bounded unmodeled dynamics. In order to compensate the effect of unmodeled dynamics and effectively achieve synchronization, a novel adaptive controller with simple updated laws is proposed. Moreover, the results are given in terms of LMIs, which can be easily solved by LMI Toolbox in Matlab. A numerical example is given to illustrate the effectiveness of the method. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Feedforward/feedback control synthesis for performance and robustness

NASA Technical Reports Server (NTRS)

Wie, Bong; Liu, Qiang

1990-01-01

Both feedforward and feedback control approaches for uncertain dynamical systems are investigated. The control design objective is to achieve a fast settling time (high performance) and robustness (insensitivity) to plant modeling uncertainty. Preshapong of an ideal, time-optimal control input using a 'tapped-delay' filter is shown to provide a rapid maneuver with robust performance. A robust, non-minimum-phase feedback controller is synthesized with particular emphasis on its proper implementation for a non-zero set-point control problem. The proposed feedforward/feedback control approach is robust for a certain class of uncertain dynamical systems, since the control input command computed for a given desired output does not depend on the plant parameters.

Interplay Between n-3 and n-6 Long-Chain Polyunsaturated Fatty Acids and the Endocannabinoid System in Brain Protection and Repair.

PubMed

Dyall, Simon C

2017-11-01

The brain is enriched in arachidonic acid (ARA) and docosahexaenoic acid (DHA), long-chain polyunsaturated fatty acids (LCPUFAs) of the n-6 and n-3 series, respectively. Both are essential for optimal brain development and function. Dietary enrichment with DHA and other long-chain n-3 PUFA, such as eicosapentaenoic acid (EPA), has shown beneficial effects on learning and memory, neuroinflammatory processes, and synaptic plasticity and neurogenesis. ARA, DHA and EPA are precursors to a diverse repertoire of bioactive lipid mediators, including endocannabinoids. The endocannabinoid system comprises cannabinoid receptors, their endogenous ligands, the endocannabinoids, and their biosynthetic and degradation enzymes. Anandamide (AEA) and 2-arachidonoylglycerol (2-AG) are the most widely studied endocannabinoids and are both derived from phospholipid-bound ARA. The endocannabinoid system also has well-established roles in neuroinflammation, synaptic plasticity and neurogenesis, suggesting an overlap in the neuroprotective effects observed with these different classes of lipids. Indeed, growing evidence suggests a complex interplay between n-3 and n-6 LCPUFA and the endocannabinoid system. For example, long-term DHA and EPA supplementation reduces AEA and 2-AG levels, with reciprocal increases in levels of the analogous endocannabinoid-like DHA and EPA-derived molecules. This review summarises current evidence of this interplay and discusses the therapeutic potential for brain protection and repair.

Uncertainty squared: Choosing among multiple input probability distributions and interpreting multiple output probability distributions in Monte Carlo climate risk models

NASA Astrophysics Data System (ADS)

Baer, P.; Mastrandrea, M.

2006-12-01

Simple probabilistic models which attempt to estimate likely transient temperature change from specified CO2 emissions scenarios must make assumptions about at least six uncertain aspects of the causal chain between emissions and temperature: current radiative forcing (including but not limited to aerosols), current land use emissions, carbon sinks, future non-CO2 forcing, ocean heat uptake, and climate sensitivity. Of these, multiple PDFs (probability density functions) have been published for the climate sensitivity, a couple for current forcing and ocean heat uptake, one for future non-CO2 forcing, and none for current land use emissions or carbon cycle uncertainty (which are interdependent). Different assumptions about these parameters, as well as different model structures, will lead to different estimates of likely temperature increase from the same emissions pathway. Thus policymakers will be faced with a range of temperature probability distributions for the same emissions scenarios, each described by a central tendency and spread. Because our conventional understanding of uncertainty and probability requires that a probabilistically defined variable of interest have only a single mean (or median, or modal) value and a well-defined spread, this "multidimensional" uncertainty defies straightforward utilization in policymaking. We suggest that there are no simple solutions to the questions raised. Crucially, we must dispel the notion that there is a "true" probability probabilities of this type are necessarily subjective, and reasonable people may disagree. Indeed, we suggest that what is at stake is precisely the question, what is it reasonable to believe, and to act as if we believe? As a preliminary suggestion, we demonstrate how the output of a simple probabilistic climate model might be evaluated regarding the reasonableness of the outputs it calculates with different input PDFs. We suggest further that where there is insufficient evidence to clearly favor one range of probabilistic projections over another, that the choice of results on which to base policy must necessarily involve ethical considerations, as they have inevitable consequences for the distribution of risk In particular, the choice to use a more "optimistic" PDF for climate sensitivity (or other components of the causal chain) leads to the allowance of higher emissions consistent with any specified goal for risk reduction, and thus leads to higher climate impacts, in exchange for lower mitigation costs.

Constructive Epistemic Modeling: A Hierarchical Bayesian Model Averaging Method

NASA Astrophysics Data System (ADS)

Tsai, F. T. C.; Elshall, A. S.

2014-12-01

Constructive epistemic modeling is the idea that our understanding of a natural system through a scientific model is a mental construct that continually develops through learning about and from the model. Using the hierarchical Bayesian model averaging (HBMA) method [1], this study shows that segregating different uncertain model components through a BMA tree of posterior model probabilities, model prediction, within-model variance, between-model variance and total model variance serves as a learning tool [2]. First, the BMA tree of posterior model probabilities permits the comparative evaluation of the candidate propositions of each uncertain model component. Second, systemic model dissection is imperative for understanding the individual contribution of each uncertain model component to the model prediction and variance. Third, the hierarchical representation of the between-model variance facilitates the prioritization of the contribution of each uncertain model component to the overall model uncertainty. We illustrate these concepts using the groundwater modeling of a siliciclastic aquifer-fault system. The sources of uncertainty considered are from geological architecture, formation dip, boundary conditions and model parameters. The study shows that the HBMA analysis helps in advancing knowledge about the model rather than forcing the model to fit a particularly understanding or merely averaging several candidate models. [1] Tsai, F. T.-C., and A. S. Elshall (2013), Hierarchical Bayesian model averaging for hydrostratigraphic modeling: Uncertainty segregation and comparative evaluation. Water Resources Research, 49, 5520-5536, doi:10.1002/wrcr.20428. [2] Elshall, A.S., and F. T.-C. Tsai (2014). Constructive epistemic modeling of groundwater flow with geological architecture and boundary condition uncertainty under Bayesian paradigm, Journal of Hydrology, 517, 105-119, doi: 10.1016/j.jhydrol.2014.05.027.

Introduced and invasive species in novel rangeland ecosystems: friends or foes?

USGS Publications Warehouse

Belnap, Jayne; Ludwig, John A.; Wilcox, Bradford P.; Betancourt, Julio L.; Dean, W. Richard J.; Hoffmann, Benjamin D.; Milton, Sue J.

2012-01-01

Globally, new combinations of introduced and native plant and animal species have changed rangelands into novel ecosystems. Whereas many rangeland stakeholders (people who use or have an interest in rangelands) view intentional species introductions to improve forage and control erosion as beneficial, others focus on unintended costs, such as increased fire risk, loss of rangeland biodiversity, and threats to conservation efforts, specifically in nature reserves and parks. These conflicting views challenge all rangeland stakeholders, especially those making decisions on how best to manage novel ecosystems. To formulate a conceptual framework for decision making, we examined a wide range of novel ecosystems, created by intentional and unintentional introductions of nonnative species and land-use–facilitated spread of native ones. This framework simply divides decision making into two types: 1) straightforward–certain, and 2) complex–uncertain. We argue that management decisions to retain novel ecosystems are certain when goods and services provided by the system far outweigh the costs of restoration, for example in the case of intensively managed Cenchrus pastures. Decisions to return novel ecosystems to natural systems are also certain when the value of the system is low and restoration is easy and inexpensive as in the case of biocontrol of Opuntia infestations. In contrast, decisions whether to retain or restore novel ecosystems become complex and uncertain in cases where benefits are low and costs of control are high as, for example, in the case of stopping the expansion of Prosopis and Juniperus into semiarid rangelands. Decisions to retain or restore novel ecosystems are also complex and uncertain when, for example, nonnative Eucalyptus trees expand along natural streams, negatively affecting biodiversity, but also providing timber and honey. When decision making is complex and uncertain, we suggest that rangeland managers utilize cost–benefit analyses and hold stakeholder workshops to resolve conflicts.

Risky Business: Development, Communication and Use of Hydroclimatic Forecasts

NASA Astrophysics Data System (ADS)

Lall, U.

2012-12-01

Inter-seasonal and longer hydroclimatic forecasts have been made increasingly in the last two decades following the increase in ENSO activity since the early 1980s and the success in seasonal ENSO forecasting. Yet, the number of examples of systematic use of these forecasts and their incorporation into water systems operation continue to be few. This may be due in part to the limited skill in such forecasts over much of the world, but is also likely due to the limited evolution of methods and opportunities to "safely" use uncertain forecasts. There has been a trend to rely more on "physically based" rather than "physically informed" empirical forecasts, and this may in part explain the limited success in developing usable products in more locations. Given the limited skill, forecasters have tended to "dumb" down their forecasts - either formally or subjectively shrinking the forecasts towards climatology, or reducing them to tercile forecasts that serve to obscure the potential information in the forecast. Consequently, the potential utility of such forecasts for decision making is compromised. Water system operating rules are often designed to be robust in the face of historical climate variability, and consequently are adapted to the potential conditions that a forecast seeks to inform. In such situations, there is understandable reluctance by managers to use the forecasts as presented, except in special cases where an alternate course of action is pragmatically appealing in any case. In this talk, I review opportunities to present targeted forecasts for use with decision systems that directly address climate risk and the risk induced by unbiased yet uncertain forecasts, focusing especially on extreme events and water allocation in a competitive environment. Examples from Brazil and India covering surface and ground water conjunctive use strategies that could potentially be insured and lead to improvements over the traditional system operation and resource allocation are provided.

Uncertain responses by humans and rhesus monkeys (Macaca mulatta) in a psychophysical same-different task

NASA Technical Reports Server (NTRS)

Shields, W. E.; Smith, J. D.; Washburn, D. A.; Rumbaugh, D. M. (Principal Investigator)

1997-01-01

The authors asked whether animals, like humans, use an uncertain response adaptively to escape indeterminate stimulus relations. Humans and monkeys were placed in a same-different task, known to be challenging for animals. Its difficulty was increased further by reducing the size of the stimulus differences, thereby making many same and different trials difficult to tell apart. Monkeys do escape selectively from these threshold trials, even while coping with 7 absolute stimulus levels concurrently. Monkeys even adjust their response strategies on short time scales according to the local task conditions. Signal-detection and optimality analyses confirm the similarity of humans' and animals' performances. Whereas associative interpretations account poorly for these results, an intuitive uncertainty construct does so easily. The authors discuss the cognitive processes that allow uncertainty's adaptive use and recommend further comparative studies of metacognition.

Learning-by-catching: uncertain invasive-species populations and the value of information.

PubMed

D'Evelyn, Sean T; Tarui, Nori; Burnett, Kimberly; Roumasset, James A

2008-12-01

This paper develops a model of invasive species control when the species' population size is unknown. In the face of an uncertain population size, a resource manager's species-control efforts provide two potential benefits: (1) a direct benefit of possibly reducing the population of invasive species, and (2) an indirect benefit of information acquisition (due to learning about the population size, which reduces uncertainty). We provide a methodology that takes into account both of these benefits, and show how optimal management decisions are altered in the presence of the indirect benefit of learning. We then apply this methodology to the case of controlling the Brown Treesnake (Boiga irregularis) on the island of Saipan. We find that the indirect benefit--the value of information to reduce uncertainty--is likely to be quite large.

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

PubMed Central

Yeow, Jonathan; Xu, Jiangtao; Boyer, Cyrille

2016-01-01

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (λ = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology. PMID:27340940

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst.

PubMed

Yeow, Jonathan; Xu, Jiangtao; Boyer, Cyrille

2016-06-08

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (λ = 460 nm, 0.7 mW/cm(2)), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

Helodermatine, a kallikrein-like, hypotensive enzyme from the venom of Heloderma horridum horridum (Mexican beaded lizard)

PubMed Central

1986-01-01

We have purified and characterized the major N-benzoyl-L-arginine ethyl ester hydrolase from the venom of Heloderma horridum horridum. The enzyme belongs to the serine proteinase family, and its activity vs. peptide amide substrates and human high-molecular-weight kininogen suggests a similarity to the family of kallikreins. This interpretation is corroborated by its reactivity with the natural inhibitors soybean trypsin inhibitor and Kunitz-type bovine pancreatic trypsin inhibitor (aprotinin). Injection of the enzyme (2-16 micrograms/kg) into anesthetized rabbits leads to a rapid dose-dependent transient decrease of the arterial blood pressure. Like glandular kallikrein it specifically converts single-chain tissue type plasminogen activator into its double chain form. In contrast to other kallikrein-like enzymes from snake venoms it shows no thrombin-like or plasminogen activator activity. The enzyme is a single-chain glycoprotein (Mr 63,000). The N-terminal sequence revealed significant homology to pig pancreatic kallikrein and to kallikrein like enzymes from Crotalus atrox and Crotalus adamanteus venom. This enzyme, which we name Helodermatine, is the first purified from Sauria with kallikrein-like properties. PMID:3537191

Sensor fault diagnosis of singular delayed LPV systems with inexact parameters: an uncertain system approach

NASA Astrophysics Data System (ADS)

Hassanabadi, Amir Hossein; Shafiee, Masoud; Puig, Vicenc

2018-01-01

In this paper, sensor fault diagnosis of a singular delayed linear parameter varying (LPV) system is considered. In the considered system, the model matrices are dependent on some parameters which are real-time measurable. The case of inexact parameter measurements is considered which is close to real situations. Fault diagnosis in this system is achieved via fault estimation. For this purpose, an augmented system is created by including sensor faults as additional system states. Then, an unknown input observer (UIO) is designed which estimates both the system states and the faults in the presence of measurement noise, disturbances and uncertainty induced by inexact measured parameters. Error dynamics and the original system constitute an uncertain system due to inconsistencies between real and measured values of the parameters. Then, the robust estimation of the system states and the faults are achieved with H∞ performance and formulated with a set of linear matrix inequalities (LMIs). The designed UIO is also applicable for fault diagnosis of singular delayed LPV systems with unmeasurable scheduling variables. The efficiency of the proposed approach is illustrated with an example.

Controlled Ring-Opening Metathesis Polymerization by Molybdenum and Tungsten Alkylidene Complexes

DTIC Science & Technology

1988-07-29

weights and low polydispersities (as low as 1.03) consistent with a living catalyst system employing 50, 100, 200, and 400 eq of monomer. The reactions are...secondary metathesis of polymer chains Bulky alkoxide ligands Wittig-like reaction Ring-opening metathesis polymerization (ROMP) Feast monomer Cyclic...olefins Retro Diels-Alder reaction Norbornene (NBE) Low temperature column chromatography Endo-,endo-5,6-dicarbomethoxynorbornene Discrete, soluble

Effects of uncertain topographic input data on two-dimensional flow modeling in a gravel-bed river

USGS Publications Warehouse

Legleiter, C.J.; Kyriakidis, P.C.; McDonald, R.R.; Nelson, J.M.

2011-01-01

Many applications in river research and management rely upon two-dimensional (2D) numerical models to characterize flow fields, assess habitat conditions, and evaluate channel stability. Predictions from such models are potentially highly uncertain due to the uncertainty associated with the topographic data provided as input. This study used a spatial stochastic simulation strategy to examine the effects of topographic uncertainty on flow modeling. Many, equally likely bed elevation realizations for a simple meander bend were generated and propagated through a typical 2D model to produce distributions of water-surface elevation, depth, velocity, and boundary shear stress at each node of the model's computational grid. Ensemble summary statistics were used to characterize the uncertainty associated with these predictions and to examine the spatial structure of this uncertainty in relation to channel morphology. Simulations conditioned to different data configurations indicated that model predictions became increasingly uncertain as the spacing between surveyed cross sections increased. Model sensitivity to topographic uncertainty was greater for base flow conditions than for a higher, subbankfull flow (75% of bankfull discharge). The degree of sensitivity also varied spatially throughout the bend, with the greatest uncertainty occurring over the point bar where the flow field was influenced by topographic steering effects. Uncertain topography can therefore introduce significant uncertainty to analyses of habitat suitability and bed mobility based on flow model output. In the presence of such uncertainty, the results of these studies are most appropriately represented in probabilistic terms using distributions of model predictions derived from a series of topographic realizations. Copyright 2011 by the American Geophysical Union.

Effect of Cholesterol on the Structure of a Five-Component Mitochondria-Like Phospholipid Membrane

PubMed Central

Cathcart, Kelly; Patel, Amit; Dies, Hannah; Rheinstädter, Maikel C.; Fradin, Cécile

2015-01-01

Cellular membranes have a complex phospholipid composition that varies greatly depending on the organism, cell type and function. In spite of this complexity, most structural data available for phospholipid bilayers concern model systems containing only one or two different phospholipids. Here, we examine the effect of cholesterol on the structure of a complex membrane reflecting the lipid composition of mitochondrial membranes, with five different types of headgroups (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS) and cardiolipin (CL)) and a variety of hydrocarbon tails. This particular system was chosen because elevated cholesterol contents in mitochondrial membranes have been linked to a breaking down of Bax-mediated membrane permeabilization and resistance to cancer treatments. High resolution electron density profiles were determined by X-ray reflectivity, while the area per phospholipid chain, Apc, and the chain order parameter, SX-ray, were determined by wide-angle X-ray scattering (WAXS). We show that chain order increases upon the addition of cholesterol, resulting in both a thickening of the lipid bilayer and a reduction in the average surface area per phospholipid chain. This effect, well known as cholesterol’s condensation effect, is similar, but not as pronounced as for single-component phospholipid membranes. We conclude by discussing the relevance of these findings for the insertion of the pro-apoptotic protein Bax in mitochondrial membranes with elevated cholesterol content. PMID:26529029

Optimality of cycle time and inventory decisions in a two echelon inventory system with exponential price dependent demand under credit period

NASA Astrophysics Data System (ADS)

Krugon, Seelam; Nagaraju, Dega

2017-05-01

This work describes and proposes an two echelon inventory system under supply chain, where the manufacturer offers credit period to the retailer with exponential price dependent demand. The model is framed as demand is expressed as exponential function of retailer’s unit selling price. Mathematical model is framed to demonstrate the optimality of cycle time, retailer replenishment quantity, number of shipments, and total relevant cost of the supply chain. The major objective of the paper is to provide trade credit concept from the manufacturer to the retailer with exponential price dependent demand. The retailer would like to delay the payments of the manufacturer. At the first stage retailer and manufacturer expressions are expressed with the functions of ordering cost, carrying cost, transportation cost. In second stage combining of the manufacturer and retailer expressions are expressed. A MATLAB program is written to derive the optimality of cycle time, retailer replenishment quantity, number of shipments, and total relevant cost of the supply chain. From the optimality criteria derived managerial insights can be made. From the research findings, it is evident that the total cost of the supply chain is decreased with the increase in credit period under exponential price dependent demand. To analyse the influence of the model parameters, parametric analysis is also done by taking with help of numerical example.

Effect of Cholesterol on the Structure of a Five-Component Mitochondria-Like Phospholipid Membrane.

PubMed

Cathcart, Kelly; Patel, Amit; Dies, Hannah; Rheinstädter, Maikel C; Fradin, Cécile

2015-10-30

Cellular membranes have a complex phospholipid composition that varies greatly depending on the organism, cell type and function. In spite of this complexity, most structural data available for phospholipid bilayers concern model systems containing only one or two different phospholipids. Here, we examine the effect of cholesterol on the structure of a complex membrane reflecting the lipid composition of mitochondrial membranes, with five different types of headgroups (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS) and cardiolipin (CL)) and a variety of hydrocarbon tails. This particular system was chosen because elevated cholesterol contents in mitochondrial membranes have been linked to a breaking down of Bax-mediated membrane permeabilization and resistance to cancer treatments. High resolution electron density profiles were determined by X-ray reflectivity, while the area per phospholipid chain, Apc, and the chain order parameter, SX-ray, were determined by wide-angle X-ray scattering (WAXS). We show that chain order increases upon the addition of cholesterol, resulting in both a thickening of the lipid bilayer and a reduction in the average surface area per phospholipid chain. This effect, well known as cholesterol's condensation effect, is similar, but not as pronounced as for single-component phospholipid membranes. We conclude by discussing the relevance of these findings for the insertion of the pro-apoptotic protein Bax in mitochondrial membranes with elevated cholesterol content.

Global sensitivity analysis in stochastic simulators of uncertain reaction networks.

PubMed

Navarro Jimenez, M; Le Maître, O P; Knio, O M

2016-12-28

Stochastic models of chemical systems are often subjected to uncertainties in kinetic parameters in addition to the inherent random nature of their dynamics. Uncertainty quantification in such systems is generally achieved by means of sensitivity analyses in which one characterizes the variability with the uncertain kinetic parameters of the first statistical moments of model predictions. In this work, we propose an original global sensitivity analysis method where the parametric and inherent variability sources are both treated through Sobol's decomposition of the variance into contributions from arbitrary subset of uncertain parameters and stochastic reaction channels. The conceptual development only assumes that the inherent and parametric sources are independent, and considers the Poisson processes in the random-time-change representation of the state dynamics as the fundamental objects governing the inherent stochasticity. A sampling algorithm is proposed to perform the global sensitivity analysis, and to estimate the partial variances and sensitivity indices characterizing the importance of the various sources of variability and their interactions. The birth-death and Schlögl models are used to illustrate both the implementation of the algorithm and the richness of the proposed analysis method. The output of the proposed sensitivity analysis is also contrasted with a local derivative-based sensitivity analysis method classically used for this type of systems.

Long-time uncertainty propagation using generalized polynomial chaos and flow map composition

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

Luchtenburg, Dirk M., E-mail: dluchten@cooper.edu; Brunton, Steven L.; Rowley, Clarence W.

2014-10-01

We present an efficient and accurate method for long-time uncertainty propagation in dynamical systems. Uncertain initial conditions and parameters are both addressed. The method approximates the intermediate short-time flow maps by spectral polynomial bases, as in the generalized polynomial chaos (gPC) method, and uses flow map composition to construct the long-time flow map. In contrast to the gPC method, this approach has spectral error convergence for both short and long integration times. The short-time flow map is characterized by small stretching and folding of the associated trajectories and hence can be well represented by a relatively low-degree basis. The compositionmore » of these low-degree polynomial bases then accurately describes the uncertainty behavior for long integration times. The key to the method is that the degree of the resulting polynomial approximation increases exponentially in the number of time intervals, while the number of polynomial coefficients either remains constant (for an autonomous system) or increases linearly in the number of time intervals (for a non-autonomous system). The findings are illustrated on several numerical examples including a nonlinear ordinary differential equation (ODE) with an uncertain initial condition, a linear ODE with an uncertain model parameter, and a two-dimensional, non-autonomous double gyre flow.« less

Global sensitivity analysis in stochastic simulators of uncertain reaction networks

DOE PAGES

Navarro Jimenez, M.; Le Maître, O. P.; Knio, O. M.

2016-12-23

Stochastic models of chemical systems are often subjected to uncertainties in kinetic parameters in addition to the inherent random nature of their dynamics. Uncertainty quantification in such systems is generally achieved by means of sensitivity analyses in which one characterizes the variability with the uncertain kinetic parameters of the first statistical moments of model predictions. In this work, we propose an original global sensitivity analysis method where the parametric and inherent variability sources are both treated through Sobol’s decomposition of the variance into contributions from arbitrary subset of uncertain parameters and stochastic reaction channels. The conceptual development only assumes thatmore » the inherent and parametric sources are independent, and considers the Poisson processes in the random-time-change representation of the state dynamics as the fundamental objects governing the inherent stochasticity. Here, a sampling algorithm is proposed to perform the global sensitivity analysis, and to estimate the partial variances and sensitivity indices characterizing the importance of the various sources of variability and their interactions. The birth-death and Schlögl models are used to illustrate both the implementation of the algorithm and the richness of the proposed analysis method. The output of the proposed sensitivity analysis is also contrasted with a local derivative-based sensitivity analysis method classically used for this type of systems.« less

Global sensitivity analysis in stochastic simulators of uncertain reaction networks

NASA Astrophysics Data System (ADS)

Navarro Jimenez, M.; Le Maître, O. P.; Knio, O. M.

2016-12-01

Stochastic models of chemical systems are often subjected to uncertainties in kinetic parameters in addition to the inherent random nature of their dynamics. Uncertainty quantification in such systems is generally achieved by means of sensitivity analyses in which one characterizes the variability with the uncertain kinetic parameters of the first statistical moments of model predictions. In this work, we propose an original global sensitivity analysis method where the parametric and inherent variability sources are both treated through Sobol's decomposition of the variance into contributions from arbitrary subset of uncertain parameters and stochastic reaction channels. The conceptual development only assumes that the inherent and parametric sources are independent, and considers the Poisson processes in the random-time-change representation of the state dynamics as the fundamental objects governing the inherent stochasticity. A sampling algorithm is proposed to perform the global sensitivity analysis, and to estimate the partial variances and sensitivity indices characterizing the importance of the various sources of variability and their interactions. The birth-death and Schlögl models are used to illustrate both the implementation of the algorithm and the richness of the proposed analysis method. The output of the proposed sensitivity analysis is also contrasted with a local derivative-based sensitivity analysis method classically used for this type of systems.

Conifer radial growth response to recent seasonal warming and drought from the southwestern USA

Treesearch

Charles Truettner; William R. L. Anderegg; Franco Biondi; George W. Koch; Kiona Ogle; Christopher Schwalm; Marcy E. Litvak; John D. Shaw; Emanuele Ziaco

2018-01-01

Future droughts are expected to become more severe and frequent under future climate change scenarios, likely causing widespread tree mortality in the western USA. Coping with an uncertain future requires an understanding of long-term ecosystem responses in areas where prolonged drought is projected to increase. Tree-ring records are ideally suited for this task. We...

Hydrologic, abiotic and biotic interactions: plant density, windspeed, leaf size and groundwater all affect oak water use efficiency

Treesearch

Darin J. Law; Deborah M. Finch

2011-01-01

Plant water use in drylands can be complex due to variation in hydrologic, abiotic and biotic factors, particularly near ephemeral or intermittent streams. Plant use of groundwater may be important but is usually uncertain. Disturbances like fire contribute to complex spatiotemporal heterogeneity. Improved understanding of how such hydrologic, abiotic, and biotic...

The Effects of Sexual Assault on the Identity Development of Black College Women

ERIC Educational Resources Information Center

Henry, Wilma J.

2009-01-01

Sexual assault victims face more social criticism than victims of any other crime. It is uncertain whether women of color are more at risk for sexual assault than White women during their college years. However, studies suggest that Black female sexual assault victims are more likely than White female victims to be blamed for their attacks and…

Thoughts and Speculations on the Possible Decline of Higher Education in the United States.

ERIC Educational Resources Information Center

Corso, Emanuele

The future of higher education is more uncertain now than it has ever been and it is interesting to examine and speculate as to causes and possible results. Values and sanctions that have previously motivated unquestioned acceptance of the legitimacy of higher education are, like many other values and sanctions in our society, presently undergoing…

What Does It Mean to Be Pragmatic? Pragmatic Methods, Measures, and Models to Facilitate Research Translation

ERIC Educational Resources Information Center

Glasgow, Russell E.

2013-01-01

Background: One of the reasons for the slow and uncertain translation of research into practice is likely due to the emphasis in science on explanatory models and efficacy designs rather than more pragmatic approaches. Methods: Following a brief definition of what constitutes a pragmatic approach, I provide examples of pragmatic methods, measures,…

What's Different for Us: Learning to Teach in Uncertain Times

ERIC Educational Resources Information Center

Dunn-Kenney, Maylan

2008-01-01

On February 14, 2008, Northern Illinois University was changed when a young man entered a large lecture hall in the center of campus and opened fire. Five students were killed that day, and the shooter died by his own hand. Many were injured physically; many more were emotionally and mentally traumatized. The violence was like a shock wave…

Small Body GN&C Research Report: A Robust Model Predictive Control Algorithm with Guaranteed Resolvability

NASA Technical Reports Server (NTRS)

Acikmese, Behcet A.; Carson, John M., III

2005-01-01

A robustly stabilizing MPC (model predictive control) algorithm for uncertain nonlinear systems is developed that guarantees the resolvability of the associated finite-horizon optimal control problem in a receding-horizon implementation. The control consists of two components; (i) feedforward, and (ii) feedback part. Feed-forward control is obtained by online solution of a finite-horizon optimal control problem for the nominal system dynamics. The feedback control policy is designed off-line based on a bound on the uncertainty in the system model. The entire controller is shown to be robustly stabilizing with a region of attraction composed of initial states for which the finite-horizon optimal control problem is feasible. The controller design for this algorithm is demonstrated on a class of systems with uncertain nonlinear terms that have norm-bounded derivatives, and derivatives in polytopes. An illustrative numerical example is also provided.

Fuzzy Adaptive Compensation Control of Uncertain Stochastic Nonlinear Systems With Actuator Failures and Input Hysteresis.

PubMed

Wang, Jianhui; Liu, Zhi; Chen, C L Philip; Zhang, Yun

2017-10-12

Hysteresis exists ubiquitously in physical actuators. Besides, actuator failures/faults may also occur in practice. Both effects would deteriorate the transient tracking performance, and even trigger instability. In this paper, we consider the problem of compensating for actuator failures and input hysteresis by proposing a fuzzy control scheme for stochastic nonlinear systems. Compared with the existing research on stochastic nonlinear uncertain systems, it is found that how to guarantee a prescribed transient tracking performance when taking into account actuator failures and hysteresis simultaneously also remains to be answered. Our proposed control scheme is designed on the basis of the fuzzy logic system and backstepping techniques for this purpose. It is proven that all the signals remain bounded and the tracking error is ensured to be within a preestablished bound with the failures of hysteretic actuator. Finally, simulations are provided to illustrate the effectiveness of the obtained theoretical results.

Adaptive Output-Feedback Neural Control of Switched Uncertain Nonlinear Systems With Average Dwell Time.

PubMed

Long, Lijun; Zhao, Jun

2015-07-01

This paper investigates the problem of adaptive neural tracking control via output-feedback for a class of switched uncertain nonlinear systems without the measurements of the system states. The unknown control signals are approximated directly by neural networks. A novel adaptive neural control technique for the problem studied is set up by exploiting the average dwell time method and backstepping. A switched filter and different update laws are designed to reduce the conservativeness caused by adoption of a common observer and a common update law for all subsystems. The proposed controllers of subsystems guarantee that all closed-loop signals remain bounded under a class of switching signals with average dwell time, while the output tracking error converges to a small neighborhood of the origin. As an application of the proposed design method, adaptive output feedback neural tracking controllers for a mass-spring-damper system are constructed.

Observer-based state tracking control of uncertain stochastic systems via repetitive controller

NASA Astrophysics Data System (ADS)

Sakthivel, R.; Susana Ramya, L.; Selvaraj, P.

2017-08-01

This paper develops the repetitive control scheme for state tracking control of uncertain stochastic time-varying delay systems via equivalent-input-disturbance approach. The main purpose of this work is to design a repetitive controller to guarantee the tracking performance under the effects of unknown disturbances with bounded frequency and parameter variations. Specifically, a new set of linear matrix inequality (LMI)-based conditions is derived based on the suitable Lyapunov-Krasovskii functional theory for designing a repetitive controller which guarantees stability and desired tracking performance. More precisely, an equivalent-input-disturbance estimator is incorporated into the control design to reduce the effect of the external disturbances. Simulation results are provided to demonstrate the desired control system stability and their tracking performance. A practical stream water quality preserving system is also provided to show the effectiveness and advantage of the proposed approach.

A Highly Sensitive Diagnostic System for Detecting Dengue Viruses Using the Interaction between a Sulfated Sugar Chain and a Virion.

PubMed

Saksono, Budi; Dewi, Beti Ernawati; Nainggolan, Leonardo; Suda, Yasuo

2015-01-01

We propose a novel method of detecting trace amounts of dengue virus (DENVs) from serum. Our method is based on the interaction between a sulfated sugar chain and a DENV surface glycoprotein. After capturing DENV with the sulfated sugar chain-immobilized gold nanoparticles (SGNPs), the resulting complex is precipitated and viral RNA content is measured using the reverse-transcription quantitative polymerase chain reaction SYBR Green I (RT-qPCR-Syb) method. Sugar chains that bind to DENVs were identified using the array-type sugar chain immobilized chip (Sugar Chip) and surface plasmon resonance (SPR) imaging. Heparin and low-molecular-weight dextran sulfate were identified as binding partners, and immobilized on gold nanoparticles to prepare 3 types of SGNPs. The capacity of these SGNPs to capture and concentrate trace amounts of DENVs was evaluated in vitro. The SGNP with greatest sensitivity was tested using clinical samples in Indonesia in 2013-2014. As a result, the novel method was able to detect low concentrations of DENVs using only 6 μL of serum, with similar sensitivity to that of a Qiagen RNA extraction kit using 140 μL of serum. In addition, this method allows for multiplex-like identification of serotypes of DENVs. This feature is important for good healthcare management of DENV infection in order to safely diagnose the dangerous, highly contagious disease quickly, with high sensitivity.

[Drug supply chain safety in hospitals: current data and experience of the Grenoble university hospital].

PubMed

Bedouch, P; Baudrant, M; Detavernier, M; Rey, C; Brudieu, E; Foroni, L; Allenet, B; Calop, J

2009-01-01

Drug supply chain safety has become a priority for public health which implies a collective process. This process associates all health professionals including the pharmacist who plays a major role. The objective of this present paper is to describe the several approaches proven effective in the reduction of drug-related problem in hospital, illustrated by the Grenoble University Hospital experience. The pharmacist gets involved first in the general strategy of hospital drug supply chain, second by his direct implication in clinical activities. The general strategy of drug supply chain combines risk management, coordination of the Pharmacy and Therapeutics Committee, selection and purchase of drugs and organisation of drug supply chain. Computer management of drug supply chain is a major evolution. Nominative drug delivering has to be a prior objective and its implementation modalities have to be defined: centralized or decentralized in wards, manual or automated. Also, new technologies allow the automation of overall drug distribution from central pharmacy and the implementation of automated drug dispensing systems into wards. The development of centralised drug preparation allows a safe compounding of high risk drugs, like cytotoxic drugs. The pharmacist should develop his clinical activities with patients and other health care professionals in order to optimise clinical decisions (medication review, drug order analysis) and patients follow-up (therapeutic monitoring, patient education, discharge consultation).

Chlorinated paraffins wrapping of carbon nanotubes: A theoretical investigation

NASA Astrophysics Data System (ADS)

Ding, Qiuyue; Ding, Ning; Chen, Xiangfeng; Wu, Chi-Man Lawrence

2018-04-01

How nanomaterials interact with pollutants is the central for understanding their environmental behavior and practical application. In this work, molecular dynamics (MD) and density functional theoretical (DFT) methods were used to investigated the influence of carbon chain length, degree of chlorination, chain configuration, and chirality of chlorinated paraffin (CP) and diameter of single-walled carbon nanotubes (SWNTs) on the interaction between CPs and SWNTs. The simulation results demonstrated that CP chain length and chlorination degree played considerably important roles in determining interaction strength between SWNTs and CPs. The interaction energies increased with increasing chain length and chlorination degree. The chirality of SWNT exerted negligible influence on the interaction energy between SWNTs and CPs. On the contrary, interaction energy increased with increasing radius of SWNTs due to the surface curvatures. This result was rationalized by considering the decrease in SWNT curvature with increasing radius, which resulted in plane-like CNT wall. The negligible influence of CP chain configurations was attributed to relative flexibility of CP carbon chains, which can wrap on tubes through conformational changes with low-energy barriers. MD results indicated that CPs could adsorb on SWNT surface rapidly in aqueous environment. Charge transfer and electronic density results indicated that the interaction between CPs and SWNTs was physisorption in nature. This work provides fundamental information regarding SWNTs as sorbents for CPs extraction and adsorptive removal from environmental water system.

Association study of Toll-like receptor 5 (TLR5) and Toll-like receptor 9 (TLR9) polymorphisms in systemic lupus erythematosus.

PubMed

Demirci, F Yesim K; Manzi, Susan; Ramsey-Goldman, Rosalind; Kenney, Margaret; Shaw, Penny S; Dunlop-Thomas, Charmayne M; Kao, Amy H; Rhew, Elisa Y; Bontempo, Franklin; Kammerer, Candace; Kamboh, M Ilyas

2007-08-01

Toll-like receptors (TLR) play an important role in both adaptive and innate immunity. Variations in TLR genes have been shown to be associated with various infectious and inflammatory diseases. We investigated the association of TLR5 (Arg392Stop, rs5744168) and TLR9 (-1237T-->C, rs5743836) single nucleotide polymorphisms (SNP) with systemic lupus erythematosus (SLE) in Caucasian American subjects. We performed a case-control association study and genotyped 409 Caucasian women with SLE and 509 Caucasian healthy female controls using TaqMan allelic discrimination (rs5744168) or polymerase chain reaction-restriction fragment length polymorphism analysis (rs5743836). None of the 2 TLR SNP showed a statistically significant association with SLE risk in our cohort. Our results do not indicate a major influence of these putative functional TLR SNP on the susceptibility to (or protection from) SLE.

Field characteristics of an alvarez-type linac structure having chain-like electrode array

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

Odera, M.; Goto, A.; Hemmi, M.

1985-10-01

A chain-like electrode configuration in an Alvarez-type linac cavity was studied by models. The structure has been devised to get a moderate shunt impedance together with simplicity of operation, in ion velocity region of more than a few percent of that of light by incorporating focusing scheme by high frequency quadrupolar fields into an TM-010 accelerating field of an Alvarez linac. It has a chain-like electrode array instead of drift tubes containing quadrupole lenses for ordinary linacs. The chain-like electrode structure generates along its central axis, high frequency acceleration and focusing fields alternately, separating the acceleration and focusing functions inmore » space. The separation discriminates this structure from spatially uniform acceleration and focusing scheme of the RFQs devised by Kapchinsky and Teplyakov. It gives beam acceleration effects different from those by conventional linacs and reveals possibility of getting a high acceleration efficiency. Resonant frequency spectrum was found relatively simple by measurements on high frequency models. Separation of unwanted modes from the TM-010 acceleration mode is large; a few 10 MHz, at least. Tilt of the acceleration field is not very sensitive to pertubation in gap capacitance for the TM-010 mode.« less

Modeling the formation of ordered nano-assemblies comprised by dendrimers and linear polyelectrolytes: The role of Coulombic interactions

NASA Astrophysics Data System (ADS)

Eleftheriou, E.; Karatasos, K.

2012-10-01

Models of mixtures of peripherally charged dendrimers with oppositely charged linear polyelectrolytes in the presence of explicit solvent are studied by means of molecular dynamics simulations. Under the influence of varying strength of electrostatic interactions, these systems appear to form dynamically arrested film-like interconnected structures in the polymer-rich phase. Acting like a pseudo-thermodynamic inverse temperature, the increase of the strength of the Coulombic interactions drive the polymeric constituents of the mixture to a gradual dynamic freezing-in. The timescale of the average density fluctuations of the formed complexes initially increases in the weak electrostatic regime reaching a finite limit as the strength of electrostatic interactions grow. Although the models are overall electrically neutral, during this process the dendrimer/linear complexes develop a polar character with an excess charge mainly close to the periphery of the dendrimers. The morphological characteristics of the resulted pattern are found to depend on the size of the polymer chains on account of the distinct conformational features assumed by the complexed linear polyelectrolytes of different length. In addition, the length of the polymer chain appears to affect the dynamics of the counterions, thus affecting the ionic transport properties of the system. It appears, therefore, that the strength of electrostatic interactions together with the length of the linear polyelectrolytes are parameters to which these systems are particularly responsive, offering thus the possibility for a better control of the resulted structure and the electric properties of these soft-colloidal systems.

Modified Bose-Einstein and Fermi-Dirac statistics if excitations are localized on an intermediate length scale: applications to non-Debye specific heat.

PubMed

Chamberlin, Ralph V; Davis, Bryce F

2013-10-01

Disordered systems show deviations from the standard Debye theory of specific heat at low temperatures. These deviations are often attributed to two-level systems of uncertain origin. We find that a source of excess specific heat comes from correlations between quanta of energy if excitations are localized on an intermediate length scale. We use simulations of a simplified Creutz model for a system of Ising-like spins coupled to a thermal bath of Einstein-like oscillators. One feature of this model is that energy is quantized in both the system and its bath, ensuring conservation of energy at every step. Another feature is that the exact entropies of both the system and its bath are known at every step, so that their temperatures can be determined independently. We find that there is a mismatch in canonical temperature between the system and its bath. In addition to the usual finite-size effects in the Bose-Einstein and Fermi-Dirac distributions, if excitations in the heat bath are localized on an intermediate length scale, this mismatch is independent of system size up to at least 10(6) particles. We use a model for correlations between quanta of energy to adjust the statistical distributions and yield a thermodynamically consistent temperature. The model includes a chemical potential for units of energy, as is often used for other types of particles that are quantized and conserved. Experimental evidence for this model comes from its ability to characterize the excess specific heat of imperfect crystals at low temperatures.

A robust adaptive observer for a class of singular nonlinear uncertain systems

NASA Astrophysics Data System (ADS)

Arefinia, Elaheh; Talebi, Heidar Ali; Doustmohammadi, Ali

2017-05-01

This paper proposes a robust adaptive observer for a class of singular nonlinear non-autonomous uncertain systems with unstructured unknown system and derivative matrices, and unknown bounded nonlinearities. Unlike many existing observers, no strong assumption such as Lipschitz condition is imposed on the recommended system. An augmented system is constructed, and the unknown bounds are calculated online using adaptive bounding technique. Considering the continuous nonlinear gain removes the chattering which may appear in practical applications such as analysis of electrical circuits and estimation of interaction force in beating heart robotic-assisted surgery. Moreover, a simple yet precise structure is attained which is easy to implement in many systems with significant uncertainties. The existence conditions of the standard form observer are obtained in terms of linear matrix inequality and the constrained generalised Sylvester's equations, and global stability is ensured. Finally, simulation results are obtained to evaluate the performance of the proposed estimator and demonstrate the effectiveness of the developed scheme.

Economic and societal dimensions of nanotechnology-enabled drug delivery.

PubMed

te Kulve, Haico; Rip, Arie

2013-05-01

There is an increasing interest in nanotechnology-enabled drug delivery systems which are expected to have significant impacts for health care. The economic and societal aspects are uncertain, even ambiguous, at this stage of development, and often not addressed, or only as part of the promises about present options. In our review we will report on assessments of actors regarding economic and societal aspects and, occasionally, of expected impacts. Topics discussed include: present and future markets of nano-enabled drug delivery, industry dynamics, regulation, cost-effectiveness, and broader ethical issues. We also include a brief discussion of anticipatory activities of actors who are concerned about these aspects. Performance of nano-enabled drug delivery, a necessary step to have future impacts at all, needs to be improved further, and in interaction with demands of users along the product value chain and with further stakeholder such as regulatory agencies and health insurers. When supported by analysis of societal embedding of new products and scenarios, this allows relevant societal and economic aspects to be taken into account at an early stage. A key issue in realizing impacts will be liability, and roles and responsibilities of technology developers and stakeholders more generally.

Development of a decision support tool for seasonal water supply management incorporating system uncertainties and operational constraints

NASA Astrophysics Data System (ADS)

Wang, H.; Asefa, T.

2017-12-01

A real-time decision support tool (DST) for water supply system would consider system uncertainties, e.g., uncertain streamflow and demand, as well as operational constraints and infrastructure outage (e.g., pump station shutdown, an offline reservoir due to maintenance). Such DST is often used by water managers for resource allocation and delivery for customers. Although most seasonal DST used by water managers recognize those system uncertainties and operational constraints, most use only historical information or assume deterministic outlook of water supply systems. This study presents a seasonal DST that incorporates rainfall/streamflow uncertainties, seasonal demand outlook and system operational constraints. Large scale climate-information is captured through a rainfall simulator driven by a Bayesian non-homogeneous Markov Chain Monte Carlo model that allows non-stationary transition probabilities contingent on Nino 3.4 index. An ad-hoc seasonal demand forecasting model considers weather conditions explicitly and socio-economic factors implicitly. Latin Hypercube sampling is employed to effectively sample probability density functions of flow and demand. Seasonal system operation is modelled as a mixed-integer optimization problem that aims at minimizing operational costs. It embeds the flexibility of modifying operational rules at different components, e.g., surface water treatment plants, desalination facilities, and groundwater pumping stations. The proposed framework is illustrated at a wholesale water supplier in Southeastern United States, Tampa Bay Water. The use of the tool is demonstrated in proving operational guidance in a typical drawdown and refill cycle of a regional reservoir. The DST provided: 1) probabilistic outlook of reservoir storage and chance of a successful refill by the end of rainy season; 2) operational expectations for large infrastructures (e.g., high service pumps and booster stations) throughout the season. Other potential use of such DST is also discussed.

[Perivascular epithelioid cell tumor, not otherwise specified: a clinicopathologic and immunohistochemical analysis of 31 cases].

PubMed

Cai, Jun-Na; Shi, Min; Wang, Jian

2011-04-01

To study the clinicopathologic characteristics of perivascular epithelioid cell tumor (PEComa), not otherwise specified (NOS) and to evaluate the diagnostic criteria for malignancy. The clinical and pathologic features of 31 cases of PEComa-NOS were reviewed. The follow-up data available were analyzed. There were a total of 24 females and 7 males. The age of the patients ranged from 13 to 66 years (mean = 40 years). The site of tumor occurrence included gynecologic organs (n = 12), intraabdominal/peritoneal soft tissue (n = 10), gastrointestinal tract (n = 4), thigh (n = 2), mediastinum (n = 1), left groin (n = 1) and urinary bladder (n = 1). None of the cases was associated with tuberous sclerosis complex. Histologic examination showed that 23 cases (74%) were clear cell sugar tumor-like, 4 cases (13%) were clear cell myomelanocytic tumor-like and 4 cases (13%) were of mixed epithelioid-spindled morphology. According to the classification system proposed by Folpe et al, 19 cases (61%) were classified as malignant, 7 cases (23%) as PEComa of uncertain malignant potential and 5 cases (16%) as benign. The expression rates of HMB45, smooth muscle actin and desmin in tested cases were 100% (31/31), 67% (14/21) and 6/18, respectively. Follow-up data (1 to 56 months) were available in 23 cases (74%). Amongst the 16 cases of malignant PEComa, 7 patients were still alive with no evidence of disease, 6 patients were alive with unresectable or recurrent/metastatic disease and 3 patients died of the disease. The local recurrence and metastasis in those 16 cases were 6 cases and 5 cases, respectively. One of the 4 patients with PEComa of uncertain malignant potential died, while the remaining 3 patients and all of the patients with benign PEComa had an uneventful clinical course. The classification system of PEComas proposed by Folpe et al. is reliable in routine practice. Correlation with the clinical and radiologic findings however is prudent when dealing with core biopsy specimens or sampling from exploration laparotomy. Owing to the histologic heterogeneity of this entity, thorough understanding of the morphologic spectrum is essential in arriving at a correct diagnosis.

Optimization of RFID network planning using Zigbee and WSN

NASA Astrophysics Data System (ADS)

Hasnan, Khalid; Ahmed, Aftab; Badrul-aisham, Bakhsh, Qadir

2015-05-01

Everyone wants to be ease in their life. Radio frequency identification (RFID) wireless technology is used to make our life easier. RFID technology increases productivity, accuracy and convenience in delivery of service in supply chain. It is used for various applications such as preventing theft of automobiles, tolls collection without stopping, no checkout lines at grocery stores, managing traffic, hospital management, corporate campuses and airports, mobile asset tracking, warehousing, tracking library books, and to track a wealth of assets in supply chain management. Efficiency of RFID can be enhanced by integrating with wireless sensor network (WSN), zigbee mesh network and internet of things (IOT). The proposed system is used for identifying, sensing and real-time locating system (RTLS) of items in an indoor heterogeneous region. The system gives real-time richer information of object's characteristics, location and their environmental parameters like temperature, noise and humidity etc. RTLS reduce human error, optimize inventory management, increase productivity and information accuracy at indoor heterogeneous network. The power consumption and the data transmission rate of the system can be minimized by using low power hardware design.

New Developments in Observer Performance Methodology in Medical Imaging

PubMed Central

Chakraborty, Dev P.

2011-01-01

A common task in medical imaging is assessing whether a new imaging system, or a variant of an existing one, is an improvement over an existing imaging technology. Imaging systems are generally quite complex, consisting of several components – e.g., image acquisition hardware, image processing and display hardware and software, and image interpretation by radiologists– each of which can affect performance. While it may appear odd to include the radiologist as a “component” of the imaging chain, since the radiologist’s decision determines subsequent patient care, the effect of the human interpretation has to be included. Physical measurements like modulation transfer function, signal to noise ratio, etc., are useful for characterizing the non-human parts of the imaging chain under idealized and often unrealistic conditions, such as uniform background phantoms, target objects with sharp edges, etc. Measuring the effect on performance of the entire imaging chain, including the radiologist, and using real clinical images, requires different methods that fall under the rubric of observer performance methods or “ROC analysis”. The purpose of this paper is to review recent developments in this field, particularly with respect to the free-response method. PMID:21978444

The Effects of the Previous Outcome on Probabilistic Choice in Rats

PubMed Central

Marshall, Andrew T.; Kirkpatrick, Kimberly

2014-01-01

This study examined the effects of previous outcomes on subsequent choices in a probabilistic-choice task. Twenty-four rats were trained to choose between a certain outcome (1 or 3 pellets) versus an uncertain outcome (3 or 9 pellets), delivered with a probability of .1, .33, .67, and .9 in different phases. Uncertain outcome choices increased with the probability of uncertain food. Additionally, uncertain choices increased with the probability of uncertain food following both certain-choice outcomes and unrewarded uncertain choices. However, following uncertain-choice food outcomes, there was a tendency to choose the uncertain outcome in all cases, indicating that the rats continued to “gamble” after successful uncertain choices, regardless of the overall probability or magnitude of food. A subsequent manipulation, in which the probability of uncertain food varied within each session as a function of the previous uncertain outcome, examined how the previous outcome and probability of uncertain food affected choice in a dynamic environment. Uncertain-choice behavior increased with the probability of uncertain food. The rats exhibited increased sensitivity to probability changes and a greater degree of win–stay/lose–shift behavior than in the static phase. Simulations of two sequential choice models were performed to explore the possible mechanisms of reward value computations. The simulation results supported an exponentially decaying value function that updated as a function of trial (rather than time). These results emphasize the importance of analyzing global and local factors in choice behavior and suggest avenues for the future development of sequential-choice models. PMID:23205915

Use of calorie information at fast food and chain restaurants among US youth aged 9-18 years, 2010.

PubMed

Wethington, H; Maynard, L M; Blanck, H M

2013-09-01

To examine whether youth use calorie information when it is available at fast food/chain restaurants and what factors are associated with using this information to make their food selection. A cross-sectional analysis was conducted on a sample of 721 youth (9-18 years) using the 2010 YouthStyles and HealthStyles surveys. The outcome measure was reported use of calorie information at fast food/chain restaurants. Multivariable logistic regression was used to examine the associations between sociodemographic variables and the use of calorie information at fast food/chain restaurants. Of those who visited fast food/chain restaurants, 42.4% reported using calorie information at least sometimes. Girls were more likely than boys (adjusted odds ratio (aOR) = 1.8, 95% confidence interval (CI) = 1.2-2.5) and youth who were obese were more likely than those at a healthy weight (aOR = 1.7, 95% CI = 1.04-2.9) to use calorie information, and youth eating at a fast food/chain restaurant twice a week or more versus once a week or less were half as likely to report using calorie information (aOR = 0.5, 95% CI = 0.4-0.8). Public health education efforts can benefit from research to determine how to increase usage among youth so that their food choices are appropriate for their caloric needs.

Heterozygous RTEL1 variants in bone marrow failure and myeloid neoplasms

PubMed Central

Marsh, Judith C. W.; Gutierrez-Rodrigues, Fernanda; Cooper, James; Jiang, Jie; Gandhi, Shreyans; Kajigaya, Sachiko; Feng, Xingmin; Ibanez, Maria del Pilar F.; Donaires, Flávia S.; Lopes da Silva, João P.; Li, Zejuan; Das, Soma; Ibanez, Maria; Smith, Alexander E.; Lea, Nicholas; Best, Steven; Ireland, Robin; Kulasekararaj, Austin G.; McLornan, Donal P.; Pagliuca, Anthony; Callebaut, Isabelle; Young, Neal S.; Calado, Rodrigo T.; Townsley, Danielle M.

2018-01-01

Biallelic germline mutations in RTEL1 (regulator of telomere elongation helicase 1) result in pathologic telomere erosion and cause dyskeratosis congenita. However, the role of RTEL1 mutations in other bone marrow failure (BMF) syndromes and myeloid neoplasms, and the contribution of monoallelic RTEL1 mutations to disease development are not well defined. We screened 516 patients for germline mutations in telomere-associated genes by next-generation sequencing in 2 independent cohorts; one constituting unselected patients with idiopathic BMF, unexplained cytopenia, or myeloid neoplasms (n = 457) and a second cohort comprising selected patients on the basis of the suspicion of constitutional/familial BMF (n = 59). Twenty-three RTEL1 variants were identified in 27 unrelated patients from both cohorts: 7 variants were likely pathogenic, 13 were of uncertain significance, and 3 were likely benign. Likely pathogenic RTEL1 variants were identified in 9 unrelated patients (7 heterozygous and 2 biallelic). Most patients were suspected to have constitutional BMF, which included aplastic anemia (AA), unexplained cytopenia, hypoplastic myelodysplastic syndrome, and macrocytosis with hypocellular bone marrow. In the other 18 patients, RTEL1 variants were likely benign or of uncertain significance. Telomeres were short in 21 patients (78%), and 3′ telomeric overhangs were significantly eroded in 4. In summary, heterozygous RTEL1 variants were associated with marrow failure, and telomere length measurement alone may not identify patients with telomere dysfunction carrying RTEL1 variants. Pathogenicity assessment of heterozygous RTEL1 variants relied on a combination of clinical, computational, and functional data required to avoid misinterpretation of common variants. PMID:29344583

Heterozygous RTEL1 variants in bone marrow failure and myeloid neoplasms.

PubMed

Marsh, Judith C W; Gutierrez-Rodrigues, Fernanda; Cooper, James; Jiang, Jie; Gandhi, Shreyans; Kajigaya, Sachiko; Feng, Xingmin; Ibanez, Maria Del Pilar F; Donaires, Flávia S; Lopes da Silva, João P; Li, Zejuan; Das, Soma; Ibanez, Maria; Smith, Alexander E; Lea, Nicholas; Best, Steven; Ireland, Robin; Kulasekararaj, Austin G; McLornan, Donal P; Pagliuca, Anthony; Callebaut, Isabelle; Young, Neal S; Calado, Rodrigo T; Townsley, Danielle M; Mufti, Ghulam J

2018-01-09

Biallelic germline mutations in RTEL1 (regulator of telomere elongation helicase 1) result in pathologic telomere erosion and cause dyskeratosis congenita. However, the role of RTEL1 mutations in other bone marrow failure (BMF) syndromes and myeloid neoplasms, and the contribution of monoallelic RTEL1 mutations to disease development are not well defined. We screened 516 patients for germline mutations in telomere-associated genes by next-generation sequencing in 2 independent cohorts; one constituting unselected patients with idiopathic BMF, unexplained cytopenia, or myeloid neoplasms (n = 457) and a second cohort comprising selected patients on the basis of the suspicion of constitutional/familial BMF (n = 59). Twenty-three RTEL1 variants were identified in 27 unrelated patients from both cohorts: 7 variants were likely pathogenic, 13 were of uncertain significance, and 3 were likely benign. Likely pathogenic RTEL1 variants were identified in 9 unrelated patients (7 heterozygous and 2 biallelic). Most patients were suspected to have constitutional BMF, which included aplastic anemia (AA), unexplained cytopenia, hypoplastic myelodysplastic syndrome, and macrocytosis with hypocellular bone marrow. In the other 18 patients, RTEL1 variants were likely benign or of uncertain significance. Telomeres were short in 21 patients (78%), and 3' telomeric overhangs were significantly eroded in 4. In summary, heterozygous RTEL1 variants were associated with marrow failure, and telomere length measurement alone may not identify patients with telomere dysfunction carrying RTEL1 variants. Pathogenicity assessment of heterozygous RTEL1 variants relied on a combination of clinical, computational, and functional data required to avoid misinterpretation of common variants.

Food product tracing technology capabilities and interoperability.

PubMed

Bhatt, Tejas; Zhang, Jianrong Janet

2013-12-01

Despite the best efforts of food safety and food defense professionals, contaminated food continues to enter the food supply. It is imperative that contaminated food be removed from the supply chain as quickly as possible to protect public health and stabilize markets. To solve this problem, scores of technology companies purport to have the most effective, economical product tracing system. This study sought to compare and contrast the effectiveness of these systems at analyzing product tracing information to identify the contaminated ingredient and likely source, as well as distribution of the product. It also determined if these systems can work together to better secure the food supply (their interoperability). Institute of Food Technologists (IFT) hypothesized that when technology providers are given a full set of supply-chain data, even for a multi-ingredient product, their systems will generally be able to trace a contaminated product forward and backward through the supply chain. However, when provided with only a portion of supply-chain data, even for a product with a straightforward supply chain, it was expected that interoperability of the systems will be lacking and that there will be difficulty collaborating to identify sources and/or recipients of potentially contaminated product. IFT provided supply-chain data for one complex product to 9 product tracing technology providers, and then compared and contrasted their effectiveness at analyzing product tracing information to identify the contaminated ingredient and likely source, as well as distribution of the product. A vertically integrated foodservice restaurant agreed to work with IFT to secure data from its supply chain for both a multi-ingredient and a simpler product. Potential multi-ingredient products considered included canned tuna, supreme pizza, and beef tacos. IFT ensured that all supply-chain data collected did not include any proprietary information or information that would otherwise identify the supply-chain partner who provided the information prior to sharing this information with product tracing technology providers. The 9 traceability solution providers who agreed to participate in this project have their systems deployed in a wide range of sectors within the food industry including, but not limited to, livestock, dairy, produce, fruits, seafood, meat, and pork; as well as in pharmaceutical, automotive, retail, and other industries. Some have also been implemented across the globe including Canada, China, USA, Norway, and the EU, among others. This broad commercial use ensures that the findings of this work are applicable to a broad spectrum of the food system. Six of the 9 participants successfully completed the data entry phase of this test. To verify successful data entry for these 6, a demo or screenshots of the data set from each system's user interface was requested. Only 4 of the 6 were able to provide us with this evidence for verification. Of the 6 that completed data entry and moved on to the scenarios phase of the test, 5 were able to provide us with the responses to the scenarios. Time metrics were useful for evaluating the scalability and usability of each technology. Scalability was derived from the time it took to enter the nonstandardized data set into the system (ranges from 7 to 11 d). Usability was derived from the time it took to query the scenarios and provide the results (from a few hours to a week). The time was measured in days it took for the participants to respond after we supplied them all the information they would need to successfully execute each test/scenario. Two of the technology solution providers successfully implemented and participated in a proof-of-concept interoperable framework during Year 2 of this study. While not required, they also demonstrated this interoperability capability on the FSMA-mandated food product tracing pilots for the U.S. FDA. This has significant real-world impact since the demonstration of interoperability enables U.S. FDA to obtain evidence on the importance and impact of data-sharing moving forward. Another real-world accomplishment is the modification or upgrade of commercial technology solutions to enhance or implement interoperability. As these systems get deployed by clients in the food industry, interoperability will no longer be an afterthought but will be built into their traceability systems. In turn, industry and regulators will better understand the capabilities of the currently available technologies, and the technology provider community will identify ways in which their systems may be further developed to increase interoperability and utility. © 2013 Institute of Food Technologists®

Predicting uncertainty in future marine ice sheet volume using Bayesian statistical methods

NASA Astrophysics Data System (ADS)

Davis, A. D.

2015-12-01

The marine ice instability can trigger rapid retreat of marine ice streams. Recent observations suggest that marine ice systems in West Antarctica have begun retreating. However, unknown ice dynamics, computationally intensive mathematical models, and uncertain parameters in these models make predicting retreat rate and ice volume difficult. In this work, we fuse current observational data with ice stream/shelf models to develop probabilistic predictions of future grounded ice sheet volume. Given observational data (e.g., thickness, surface elevation, and velocity) and a forward model that relates uncertain parameters (e.g., basal friction and basal topography) to these observations, we use a Bayesian framework to define a posterior distribution over the parameters. A stochastic predictive model then propagates uncertainties in these parameters to uncertainty in a particular quantity of interest (QoI)---here, the volume of grounded ice at a specified future time. While the Bayesian approach can in principle characterize the posterior predictive distribution of the QoI, the computational cost of both the forward and predictive models makes this effort prohibitively expensive. To tackle this challenge, we introduce a new Markov chain Monte Carlo method that constructs convergent approximations of the QoI target density in an online fashion, yielding accurate characterizations of future ice sheet volume at significantly reduced computational cost.Our second goal is to attribute uncertainty in these Bayesian predictions to uncertainties in particular parameters. Doing so can help target data collection, for the purpose of constraining the parameters that contribute most strongly to uncertainty in the future volume of grounded ice. For instance, smaller uncertainties in parameters to which the QoI is highly sensitive may account for more variability in the prediction than larger uncertainties in parameters to which the QoI is less sensitive. We use global sensitivity analysis to help answer this question, and make the computation of sensitivity indices computationally tractable using a combination of polynomial chaos and Monte Carlo techniques.

The Buccaneer software for automated model building. 1. Tracing protein chains.

PubMed

Cowtan, Kevin

2006-09-01

A new technique for the automated tracing of protein chains in experimental electron-density maps is described. The technique relies on the repeated application of an oriented electron-density likelihood target function to identify likely C(alpha) positions. This function is applied both in the location of a few promising ;seed' positions in the map and to grow those initial C(alpha) positions into extended chain fragments. Techniques for assembling the chain fragments into an initial chain trace are discussed.

Personal Protective Equipment Supply Chain: Lessons Learned from Recent Public Health Emergency Responses.

PubMed

Patel, Anita; D'Alessandro, Maryann M; Ireland, Karen J; Burel, W Greg; Wencil, Elaine B; Rasmussen, Sonja A

Personal protective equipment (PPE) that protects healthcare workers from infection is a critical component of infection control strategies in healthcare settings. During a public health emergency response, protecting healthcare workers from infectious disease is essential, given that they provide clinical care to those who fall ill, have a high risk of exposure, and need to be assured of occupational safety. Like most goods in the United States, the PPE market supply is based on demand. The US PPE supply chain has minimal ability to rapidly surge production, resulting in challenges to meeting large unexpected increases in demand that might occur during a public health emergency. Additionally, a significant proportion of the supply chain is produced off-shore and might not be available to the US market during an emergency because of export restrictions or nationalization of manufacturing facilities. Efforts to increase supplies during previous public health emergencies have been challenging. During the 2009 H1N1 influenza pandemic and the 2014 Ebola virus epidemic, the commercial supply chain of pharmaceutical and healthcare products quickly became critical response components. This article reviews lessons learned from these responses from a PPE supply chain and systems perspective and examines ways to improve PPE readiness for future responses.

Peculiar spectral statistics of ensembles of trees and star-like graphs

NASA Astrophysics Data System (ADS)

Kovaleva, V.; Maximov, Yu; Nechaev, S.; Valba, O.

2017-07-01

In this paper we investigate the eigenvalue statistics of exponentially weighted ensembles of full binary trees and p-branching star graphs. We show that spectral densities of corresponding adjacency matrices demonstrate peculiar ultrametric structure inherent to sparse systems. In particular, the tails of the distribution for binary trees share the ‘Lifshitz singularity’ emerging in the one-dimensional localization, while the spectral statistics of p-branching star-like graphs is less universal, being strongly dependent on p. The hierarchical structure of spectra of adjacency matrices is interpreted as sets of resonance frequencies, that emerge in ensembles of fully branched tree-like systems, known as dendrimers. However, the relaxational spectrum is not determined by the cluster topology, but has rather the number-theoretic origin, reflecting the peculiarities of the rare-event statistics typical for one-dimensional systems with a quenched structural disorder. The similarity of spectral densities of an individual dendrimer and of an ensemble of linear chains with exponential distribution in lengths, demonstrates that dendrimers could be served as simple disorder-less toy models of one-dimensional systems with quenched disorder.

Peculiar spectral statistics of ensembles of trees and star-like graphs

DOE PAGES

Kovaleva, V.; Maximov, Yu; Nechaev, S.; ...

2017-07-11

In this paper we investigate the eigenvalue statistics of exponentially weighted ensembles of full binary trees and p-branching star graphs. We show that spectral densities of corresponding adjacency matrices demonstrate peculiar ultrametric structure inherent to sparse systems. In particular, the tails of the distribution for binary trees share the \\Lifshitz singularity" emerging in the onedimensional localization, while the spectral statistics of p-branching star-like graphs is less universal, being strongly dependent on p. The hierarchical structure of spectra of adjacency matrices is interpreted as sets of resonance frequencies, that emerge in ensembles of fully branched tree-like systems, known as dendrimers. However,more » the relaxational spectrum is not determined by the cluster topology, but has rather the number-theoretic origin, re ecting the peculiarities of the rare-event statistics typical for one-dimensional systems with a quenched structural disorder. The similarity of spectral densities of an individual dendrimer and of ensemble of linear chains with exponential distribution in lengths, demonstrates that dendrimers could be served as simple disorder-less toy models of one-dimensional systems with quenched disorder.« less

Peculiar spectral statistics of ensembles of trees and star-like graphs

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

Kovaleva, V.; Maximov, Yu; Nechaev, S.

In this paper we investigate the eigenvalue statistics of exponentially weighted ensembles of full binary trees and p-branching star graphs. We show that spectral densities of corresponding adjacency matrices demonstrate peculiar ultrametric structure inherent to sparse systems. In particular, the tails of the distribution for binary trees share the \\Lifshitz singularity" emerging in the onedimensional localization, while the spectral statistics of p-branching star-like graphs is less universal, being strongly dependent on p. The hierarchical structure of spectra of adjacency matrices is interpreted as sets of resonance frequencies, that emerge in ensembles of fully branched tree-like systems, known as dendrimers. However,more » the relaxational spectrum is not determined by the cluster topology, but has rather the number-theoretic origin, re ecting the peculiarities of the rare-event statistics typical for one-dimensional systems with a quenched structural disorder. The similarity of spectral densities of an individual dendrimer and of ensemble of linear chains with exponential distribution in lengths, demonstrates that dendrimers could be served as simple disorder-less toy models of one-dimensional systems with quenched disorder.« less

Do resource utilization and clinical measures still vary across dialysis chains after controlling for the local practices of facilities and physicians?

PubMed

Hirth, Richard A; Turenne, Marc N; Wheeler, John R C; Ma, Yu; Messana, Joseph M

2010-08-01

Because of adverse survival effects, anemia management and financial incentives to increase doses of erythropoiesis-stimulating agents (ESAs) have been controversial. Prior studies showed more aggressive anemia management in dialysis facilities owned by for-profit chains, but have been criticized for not accounting for practices of individual physicians and facilities. To improve understanding of how dialysis practices and resource utilization are influenced by physicians, facilities, and chains. Mixed models with chain fixed effects and facility and physician random effects. Medicare hemodialysis patients in 2004. A total of 234,158 patients, 3995 facilities, 4838 physicians, and 7 chain classifications were included. Spending per session for dialysis-related services billed separately from the dialysis treatment and for ESAs. Achievement of hematocrit (HCT) and urea reduction ratio (URR) targets. Of the 4 largest for-profit chains, 3 had higher resource use than independents, with differences up to $17.92 higher ESA/session. Utilization was positively associated with achieving target HCT. Despite incurring lower costs, patients treated by a large nonprofit chain were as likely as patients of independents to achieve the HCT target. The largest chains were more likely than independents to achieve the URR target. Substantial variation occurred across physicians and facilities, and adjustment for chain only modestly decreased this variation. Chains' methods of influencing practices were not directly observed. Chains appear to have the ability to implement protocols that shift practices, but not the ability to substantially reduce local variation. Assertions that chain effects found by earlier studies were spurious are not supported.

Composite Robust $$H_\\infty$$ Control for Uncertain Stochastic Nonlinear Systems with State Delay via Disturbance Observer

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

Liu, Yunlong; Wang, Hong; Guo, Lei

Here in this note, the robust stochastic stabilization and robust H_infinity control problems are investigated for uncertain stochastic time-delay systems with nonlinearity and multiple disturbances. By estimating the disturbance, which can be described by an exogenous model, a composite hierarchical control scheme is proposed that integrates the output of the disturbance observer with state feedback control law. Sufficient conditions for the existence of the disturbance observer and composite hierarchical controller are established in terms of linear matrix inequalities, which ensure the mean-square asymptotic stability of the resulting closed-loop system and the disturbance attenuation. It has been shown that the disturbancemore » rejection performance can also be achieved. A numerical example is provided to show the potential of the proposed techniques and encouraging results have been obtained.« less

An interval precise integration method for transient unbalance response analysis of rotor system with uncertainty

NASA Astrophysics Data System (ADS)

Fu, Chao; Ren, Xingmin; Yang, Yongfeng; Xia, Yebao; Deng, Wangqun

2018-07-01

A non-intrusive interval precise integration method (IPIM) is proposed in this paper to analyze the transient unbalance response of uncertain rotor systems. The transfer matrix method (TMM) is used to derive the deterministic equations of motion of a hollow-shaft overhung rotor. The uncertain transient dynamic problem is solved by combing the Chebyshev approximation theory with the modified precise integration method (PIM). Transient response bounds are calculated by interval arithmetic of the expansion coefficients. Theoretical error analysis of the proposed method is provided briefly, and its accuracy is further validated by comparing with the scanning method in simulations. Numerical results show that the IPIM can keep good accuracy in vibration prediction of the start-up transient process. Furthermore, the proposed method can also provide theoretical guidance to other transient dynamic mechanical systems with uncertainties.

Almost output regulation of LFT systems via gain-scheduling control

NASA Astrophysics Data System (ADS)

Yuan, Chengzhi; Duan, Chang; Wu, Fen

2018-05-01

Output regulation of general uncertain systems is a meaningful yet challenging problem. In spite of the rich literature in the field, the problem has not yet been addressed adequately due to the lack of an effective design mechanism. In this paper, we propose a new design framework for almost output regulation of uncertain systems described in the general form of linear fractional transformation (LFT) with time-varying parametric uncertainties and unknown external perturbations. A novel semi-LFT gain-scheduling output regulator structure is proposed, such that the associated control synthesis conditions guaranteeing both output regulation and ? disturbance attenuation performance are formulated as a set of linear matrix inequalities (LMIs) plus parameter-dependent linear matrix equations, which can be solved separately. A numerical example has been used to demonstrate the effectiveness of the proposed approach.

Finite-time output feedback control of uncertain switched systems via sliding mode design

NASA Astrophysics Data System (ADS)

Zhao, Haijuan; Niu, Yugang; Song, Jun

2018-04-01

The problem of sliding mode control (SMC) is investigated for a class of uncertain switched systems subject to unmeasurable state and assigned finite (possible short) time constraint. A key issue is how to ensure the finite-time boundedness (FTB) of system state during reaching phase and sliding motion phase. To this end, a state observer is constructed to estimate the unmeasured states. And then, a state estimate-based SMC law is designed such that the state trajectories can be driven onto the specified integral sliding surface during the assigned finite time interval. By means of partitioning strategy, the corresponding FTB over reaching phase and sliding motion phase are guaranteed and the sufficient conditions are derived via average dwell time technique. Finally, an illustrative example is given to illustrate the proposed method.

Composite Robust $$H_\\infty$$ Control for Uncertain Stochastic Nonlinear Systems with State Delay via Disturbance Observer

DOE PAGES

Liu, Yunlong; Wang, Hong; Guo, Lei

2018-03-26

Here in this note, the robust stochastic stabilization and robust H_infinity control problems are investigated for uncertain stochastic time-delay systems with nonlinearity and multiple disturbances. By estimating the disturbance, which can be described by an exogenous model, a composite hierarchical control scheme is proposed that integrates the output of the disturbance observer with state feedback control law. Sufficient conditions for the existence of the disturbance observer and composite hierarchical controller are established in terms of linear matrix inequalities, which ensure the mean-square asymptotic stability of the resulting closed-loop system and the disturbance attenuation. It has been shown that the disturbancemore » rejection performance can also be achieved. A numerical example is provided to show the potential of the proposed techniques and encouraging results have been obtained.« less

Risk and resilience in an uncertain world

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Dale, Virginia H.; Jager, Henriette I.; Wolfe, Amy K.; ...

2018-02-01

We report that because the future is uncertain and to some extent unknowable, it is imperative that ecologists become involved in the discussion and planning of future infrastructure and protection from the effects of altered disturbance regimes. Research can test and demonstrate the benefits of protecting or proactively managing important features and places, and processes that enhance provisioning of ecosystem services such as flood control and fire mitigation. In conclusion, it is time to demonstrate how ecological science, when applied to human–environmental systems, can reduce risks and enhance resilience in a complex, changing world.