Evolving earth-based and in-situ satellite network architectures for Mars communications and navigation support

NASA Astrophysics Data System (ADS)

Hastrup, Rolf; Weinberg, Aaron; McOmber, Robert

1991-09-01

Results of on-going studies to develop navigation/telecommunications network concepts to support future robotic and human missions to Mars are presented. The performance and connectivity improvements provided by the relay network will permit use of simpler, lower performance, and less costly telecom subsystems for the in-situ mission exploration elements. Orbiting relay satellites can serve as effective navigation aids by supporting earth-based tracking as well as providing Mars-centered radiometric data for mission elements approaching, in orbit, or on the surface of Mars. The relay satellite orbits may be selected to optimize navigation aid support and communication coverage for specific mission sets.

Conjunctive coding in an evolved spiking model of retrosplenial cortex.

PubMed

Rounds, Emily L; Alexander, Andrew S; Nitz, Douglas A; Krichmar, Jeffrey L

2018-06-04

Retrosplenial cortex (RSC) is an association cortex supporting spatial navigation and memory. However, critical issues remain concerning the forms by which its ensemble spiking patterns register spatial relationships that are difficult for experimental techniques to fully address. We therefore applied an evolutionary algorithmic optimization technique to create spiking neural network models that matched electrophysiologically observed spiking dynamics in rat RSC neuronal ensembles. Virtual experiments conducted on the evolved networks revealed a mixed selectivity coding capability that was not built into the optimization method, but instead emerged as a consequence of replicating biological firing patterns. The experiments reveal several important outcomes of mixed selectivity that may subserve flexible navigation and spatial representation: (a) robustness to loss of specific inputs, (b) immediate and stable encoding of novel routes and route locations, (c) automatic resolution of input variable conflicts, and (d) dynamic coding that allows rapid adaptation to changing task demands without retraining. These findings suggest that biological retrosplenial cortex can generate unique, first-trial, conjunctive encodings of spatial positions and actions that can be used by downstream brain regions for navigation and path integration. Moreover, these results are consistent with the proposed role for the RSC in the transformation of representations between reference frames and navigation strategy deployment. Finally, the specific modeling framework used for evolving synthetic retrosplenial networks represents an important advance for computational modeling by which synthetic neural networks can encapsulate, describe, and predict the behavior of neural circuits at multiple levels of function. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Maximum Correntropy Unscented Kalman Filter for Ballistic Missile Navigation System based on SINS/CNS Deeply Integrated Mode.

PubMed

Hou, Bowen; He, Zhangming; Li, Dong; Zhou, Haiyin; Wang, Jiongqi

2018-05-27

Strap-down inertial navigation system/celestial navigation system ( SINS/CNS) integrated navigation is a high precision navigation technique for ballistic missiles. The traditional navigation method has a divergence in the position error. A deeply integrated mode for SINS/CNS navigation system is proposed to improve the navigation accuracy of ballistic missile. The deeply integrated navigation principle is described and the observability of the navigation system is analyzed. The nonlinearity, as well as the large outliers and the Gaussian mixture noises, often exists during the actual navigation process, leading to the divergence phenomenon of the navigation filter. The new nonlinear Kalman filter on the basis of the maximum correntropy theory and unscented transformation, named the maximum correntropy unscented Kalman filter, is deduced, and the computational complexity is analyzed. The unscented transformation is used for restricting the nonlinearity of the system equation, and the maximum correntropy theory is used to deal with the non-Gaussian noises. Finally, numerical simulation illustrates the superiority of the proposed filter compared with the traditional unscented Kalman filter. The comparison results show that the large outliers and the influence of non-Gaussian noises for SINS/CNS deeply integrated navigation is significantly reduced through the proposed filter.

Connectivism and Information Literacy: Moving from Learning Theory to Pedagogical Practice

ERIC Educational Resources Information Center

Transue, Beth M.

2013-01-01

Connectivism is an emerging learning theory positing that knowledge comprises networked relationships and that learning comprises the ability to successfully navigate through these networks. Successful pedagogical strategies involve the instructor helping students to identify, navigate, and evaluate information from their learning networks. Many…

Optical Navigation Simulation and Performance Analysis for Osiris-Rex Proximity Operations

NASA Technical Reports Server (NTRS)

Jackman, Coralie D.; Nelson, Derek S.; Mccarthy, Leilah K.; Liounis, Andrew J.; Leonard, Jason M.; Antreasian, Peter G.; Getzandanner, Kenneth M.; Moreau, Michael C.

2017-01-01

The OSIRIS-REx mission timeline with OpNav milestones is presented in Figure 1. The first three proximity operations (ProxOps) mission phases focus on Navigation. During these phases, OSIRIS-REx approaches Bennu, conducts equatorial and polar flybys in Preliminary Survey, and inserts into the first mission orbit: Orbit A. During these phases, the OpNav techniques evolve from point-source to resolved-body centroiding to landmark tracking.

A Novel Robust H∞ Filter Based on Krein Space Theory in the SINS/CNS Attitude Reference System.

PubMed

Yu, Fei; Lv, Chongyang; Dong, Qianhui

2016-03-18

Owing to their numerous merits, such as compact, autonomous and independence, the strapdown inertial navigation system (SINS) and celestial navigation system (CNS) can be used in marine applications. What is more, due to the complementary navigation information obtained from two different kinds of sensors, the accuracy of the SINS/CNS integrated navigation system can be enhanced availably. Thus, the SINS/CNS system is widely used in the marine navigation field. However, the CNS is easily interfered with by the surroundings, which will lead to the output being discontinuous. Thus, the uncertainty problem caused by the lost measurement will reduce the system accuracy. In this paper, a robust H∞ filter based on the Krein space theory is proposed. The Krein space theory is introduced firstly, and then, the linear state and observation models of the SINS/CNS integrated navigation system are established reasonably. By taking the uncertainty problem into account, in this paper, a new robust H∞ filter is proposed to improve the robustness of the integrated system. At last, this new robust filter based on the Krein space theory is estimated by numerical simulations and actual experiments. Additionally, the simulation and experiment results and analysis show that the attitude errors can be reduced by utilizing the proposed robust filter effectively when the measurements are missing discontinuous. Compared to the traditional Kalman filter (KF) method, the accuracy of the SINS/CNS integrated system is improved, verifying the robustness and the availability of the proposed robust H∞ filter.

Coordinated prefrontal-hippocampal activity and navigation strategy-related prefrontal firing during spatial memory formation.

PubMed

Negrón-Oyarzo, Ignacio; Espinosa, Nelson; Aguilar, Marcelo; Fuenzalida, Marco; Aboitiz, Francisco; Fuentealba, Pablo

2018-06-18

Learning the location of relevant places in the environment is crucial for survival. Such capacity is supported by a distributed network comprising the prefrontal cortex and hippocampus, yet it is not fully understood how these structures cooperate during spatial reference memory formation. Hence, we examined neural activity in the prefrontal-hippocampal circuit in mice during acquisition of spatial reference memory. We found that interregional oscillatory coupling increased with learning, specifically in the slow-gamma frequency (20 to 40 Hz) band during spatial navigation. In addition, mice used both spatial and nonspatial strategies to navigate and solve the task, yet prefrontal neuronal spiking and oscillatory phase coupling were selectively enhanced in the spatial navigation strategy. Lastly, a representation of the behavioral goal emerged in prefrontal spiking patterns exclusively in the spatial navigation strategy. These results suggest that reference memory formation is supported by enhanced cortical connectivity and evolving prefrontal spiking representations of behavioral goals.

The Electra proximity link payload for Mars relay telecommunications and navigation

NASA Technical Reports Server (NTRS)

Edwards, C. D.; Jedrey, T. C.; Devereaux, A. S.; DePaula, R.; Dapore, M.

2003-01-01

We present here the functional requirements, design characteristics, and implementational status of the Electra Payload and its role as a telecommunications mode in an evolving Mars orbital infrastructure.

A Novel Robust H∞ Filter Based on Krein Space Theory in the SINS/CNS Attitude Reference System

PubMed Central

Yu, Fei; Lv, Chongyang; Dong, Qianhui

2016-01-01

Owing to their numerous merits, such as compact, autonomous and independence, the strapdown inertial navigation system (SINS) and celestial navigation system (CNS) can be used in marine applications. What is more, due to the complementary navigation information obtained from two different kinds of sensors, the accuracy of the SINS/CNS integrated navigation system can be enhanced availably. Thus, the SINS/CNS system is widely used in the marine navigation field. However, the CNS is easily interfered with by the surroundings, which will lead to the output being discontinuous. Thus, the uncertainty problem caused by the lost measurement will reduce the system accuracy. In this paper, a robust H∞ filter based on the Krein space theory is proposed. The Krein space theory is introduced firstly, and then, the linear state and observation models of the SINS/CNS integrated navigation system are established reasonably. By taking the uncertainty problem into account, in this paper, a new robust H∞ filter is proposed to improve the robustness of the integrated system. At last, this new robust filter based on the Krein space theory is estimated by numerical simulations and actual experiments. Additionally, the simulation and experiment results and analysis show that the attitude errors can be reduced by utilizing the proposed robust filter effectively when the measurements are missing discontinuous. Compared to the traditional Kalman filter (KF) method, the accuracy of the SINS/CNS integrated system is improved, verifying the robustness and the availability of the proposed robust H∞ filter. PMID:26999153

Memorable Messages for Navigating College Life

ERIC Educational Resources Information Center

Nazione, Samantha; Laplante, Carolyn; Smith, Sandi W.; Cornacchione, Jennifer; Russell, Jessica; Stohl, Cynthia

2011-01-01

This manuscript details an investigation of memorable messages that help students navigate college life using a control theory framework. Researchers conducted face-to-face interviews with 61 undergraduate students who recalled a specific memorable message that helped them as they navigated college. Results of this formative study show the…

NOAA Photo Library - The Coral Kingdom

Science.gov Websites

that corals evolved into modern reef-building organisms within the past 25 million years. Over those navigation of the Florida Straits. Today, coral reefs, both modern and fossil, are studied as indicators of

Cyberspace Operations: Influence Upon Evolving War Theory

DTIC Science & Technology

2011-03-18

St ra te gy R es ea rc h Pr oj ec t CYBERSPACE OPERATIONS: INFLUENCE UPON EVOLVING WAR THEORY BY COLONEL KRISTIN BAKER United States...DATES COVERED (From - To) 4. TITLE AND SUBTITLE Cyberspace Operations: Influence Upon Evolving War Theory 5a. CONTRACT NUMBER... Leadership 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S

Development of Mission Enabling Infrastructure — Cislunar Autonomous Positioning System (CAPS)

NASA Astrophysics Data System (ADS)

Cheetham, B. W.

2017-10-01

Advanced Space, LLC is developing the Cislunar Autonomous Positioning System (CAPS) which would provide a scalable and evolvable architecture for navigation to reduce ground congestion and improve operations for missions throughout cislunar space.

Physician's emerging roles relating to trends in health information technology.

PubMed

David Johnson, J

2014-08-12

Objective: To determine the new roles that physicians will adopt in the near future to adjust to accelerating trends from managed care to outcome-based practice to health care reform to health information technology to the evolving role of health consumers. Methods: Trends and related developments concerning the changing roles of physicians based on prior literature reviews. Results: Six possible roles, traditional, gatekeeper, coach, navigator, informatician and one voice among many, are discussed in terms of physician's centrality, patient autonomy, decision-making and uncertainty, information seeking, satisfaction and outcomes, particularly those related to compliance. Conclusion: A greater understanding of these emerging roles could lead to more efficacious outcomes in our ever changing, increasingly complex medical system. Patients often have little understanding of emerging trends that lead to the development of specialized roles such as hospitalist and navigators and, relatedly, the evolving roles of physicians.

National aerospace meeting of the Institute of Navigation

NASA Astrophysics Data System (ADS)

Fell, Patrick

The program for this year's aerospace meeting of The Institute of Navigation addressed developments in the evolving Global Positioning System (GPS) of navigation satellites, inertial navigation systems, and other electronic navigation systems and their applications. Also included in the program were a limited number of papers addressing the geodetic use of the GPS system.The Global Positioning System is a constellation of 18 navigation satellites being developed by the Department of Defense to provide instantaneous worldwide navigation. The system will support a multitude of military applications. The first paper by Jacobson reviewed the engineering development of GPS navigation receivers stressing the use of common hardware and software modules. A later paper by Ould described the mechanization of a digital receiver for GPS applications designed for faster acquisition of the spread spectrum satellite transmissions than analog receivers. The paper by Brady discussed the worldwide coverage that is provided by the limited number of satellites that will constitute the GPS constellation through 1983. The capability provided by the satellites presently on orbit would support a variety of experiments at almost any location. Tables of multiple satellite availability are provided for numerous worldwide locations. For civil aviation applications, Vogel addressed the satellite geometry considerations for low cost GPS user equipment, Esposito described the Federal Aviation Administration acceptance tests of a GPS navigation receiver, and Hopkins discussed the design and capability of an integrated GPS strapdown attitude and heading reference system for avionics.

Navigation Patterns and Scent Marking: Underappreciated Contributors to Hippocampal and Entorhinal Spatial Representations?

PubMed

Lebedev, Mikhail A; Pimashkin, Alexey; Ossadtchi, Alexei

2018-01-01

According to the currently prevailing theory, hippocampal formation constructs and maintains cognitive spatial maps. Most of the experimental evidence for this theory comes from the studies on navigation in laboratory rats and mice, typically male animals. While these animals exhibit a rich repertoire of behaviors associated with navigation, including locomotion, head movements, whisking, sniffing, raring and scent marking, the contribution of these behavioral patterns to the hippocampal spatially-selective activity has not been sufficiently studied. Instead, many publications have considered animal position in space as the major variable that affects the firing of hippocampal place cells and entorhinal grid cells. Here we argue that future work should focus on a more detailed examination of different behaviors exhibited during navigation to better understand the mechanism of spatial tuning in hippocampal neurons. As an inquiry in this direction, we have analyzed data from two datasets, shared online, containing recordings from rats navigating in square and round arenas. Our analyses revealed patchy navigation patterns, evident from the spatial maps of animal position, velocity and acceleration. Moreover, grid cells available in the datasets exhibited similar periodicity as the navigation parameters. These findings indicate that activity of grid cells could affect navigation parameters and/or vice versa. Additionally, we speculate that scent marks left by navigating animals could contribute to neuronal responses while rats and mice sniff their environment; the act of sniffing could modulate neuronal discharges even in virtual visual environments. Accordingly, we propose that future experiments should contain additional controls for navigation patterns, whisking, sniffing and maps composed of scent marks.

Unraveling navigational strategies in migratory insects

PubMed Central

Merlin, Christine; Heinze, Stanley; Reppert, Steven M.

2011-01-01

Long-distance migration is a strategy some animals use to survive a seasonally changing environment. To reach favorable grounds, migratory animals have evolved sophisticated navigational mechanisms that rely on a map and compasses. In migratory insects, the existence of a map sense (sense of position) remains poorly understood, but recent work has provided new insights into the mechanisms some compasses use for maintaining a constant bearing during long-distance navigation. The best-studied directional strategy relies on a time-compensated sun compass, used by diurnal insects, for which neural circuits have begun to be delineated. Yet, a growing body of evidence suggests that migratory insects may also rely on other compasses that use night sky cues or the Earth's magnetic field. Those mechanisms are ripe for exploration. PMID:22154565

An Interactive, Physics-Based Unmanned Ground Vehicle Simulator Leveraging Open Source Gaming Technology: Progress in the Development and Application of the Virtual Autonomous Navigation Environment (VANE) Desktop

DTIC Science & Technology

2009-01-01

interface, mechatronics, video games 1. INTRODUCTION Engineering methods have substantially and continuously evolved over the past 40 years. In the past...1970s, video games have pioneered interactive simulation and laid the groundwork for inexpensive computing that individuals, corporations, and...purposes. This has not gone unnoticed, and software technology and techniques evolved for video games are beginning to have extraordinary impact in

An analysis of approach navigation accuracy and guidance requirements for the grand tour mission to the outer planets

NASA Technical Reports Server (NTRS)

Jones, D. W.

1971-01-01

The navigation and guidance process for the Jupiter, Saturn and Uranus planetary encounter phases of the 1977 Grand Tour interior mission was simulated. Reference approach navigation accuracies were defined and the relative information content of the various observation types were evaluated. Reference encounter guidance requirements were defined, sensitivities to assumed simulation model parameters were determined and the adequacy of the linear estimation theory was assessed. A linear sequential estimator was used to provide an estimate of the augmented state vector, consisting of the six state variables of position and velocity plus the three components of a planet position bias. The guidance process was simulated using a nonspherical model of the execution errors. Computation algorithms which simulate the navigation and guidance process were derived from theory and implemented into two research-oriented computer programs, written in FORTRAN.

The Evolution of Constructivist Learning Environments: Immersion in Distributed, Virtual Worlds.

ERIC Educational Resources Information Center

Dede, Chris

1995-01-01

Discusses the evolution of constructivist learning environments and examines the collaboration of simulated software models, virtual environments, and evolving mental models via immersion in artificial realities. A sidebar gives a realistic example of a student navigating through cyberspace. (JMV)

Theory of the evolutionary minority game

NASA Astrophysics Data System (ADS)

Lo, T. S.; Hui, P. M.; Johnson, N. F.

2000-09-01

We present a theory describing a recently introduced model of an evolving, adaptive system in which agents compete to be in the minority. The agents themselves are able to evolve their strategies over time in an attempt to improve their performance. The theory explicitly demonstrates the self-interaction, or market impact, that agents in such systems experience.

The attribution of navigational- and goal-directed agency in dogs (Canis familiaris) and human toddlers (Homo sapiens).

PubMed

Tauzin, Tibor; Csík, Andor; Lovas, Kata; Gergely, György; Topál, József

2017-02-01

Both human infants and nonhuman primates can recognize unfamiliar entities as instrumental agents ascribing to them goals and efficiency of goal-pursuit. This competence relies on movement cues indicating distal sensitivity to the environment and choice of efficient goal-approach. Although dogs' evolved sensitivity to social cues allow them to recognize humans as communicative agents, it remains unclear whether they have also evolved a basic concept of instrumental agency. We used a preferential object-choice procedure to test whether adult pet dogs and human toddlers can identify unfamiliar entities as agents based on different types of movement cues that specify different levels of agency. In the navigational agency condition, dogs preferentially chose an object that modified its pathway to avoid collision with obstacles over another object showing no evidence of distal sensitivity (regularly bumping into obstacles). However, in the goal-efficiency condition where neither object collided with obstacles as it navigated toward a distal target, but only 1 of them exhibited efficient goal-approach as well, toddlers, but not dogs, showed a preference toward the efficient goal-directed agent. These findings indicate that dogs possess a limited concept of environmentally sensitive navigational agency that they attribute to self-propelled entities capable of modifying their movement to avoid colliding with obstacles. Toddlers, in contrast, demonstrated clear sensitivity to cues of efficient variability of goal-approach as the basis for differentiating, attributing, and showing preference for goal-directed instrumental agency. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Flight Mechanics/Estimation Theory Symposium

NASA Technical Reports Server (NTRS)

1978-01-01

Satellite attitude determination and control, orbit determination, and onboard and ground attitude determination procedures are among the topics discussed. Other topics covered include: effect of atmosphere on Venus orbiter navigation; satellite-to-satellite tracking; and satellite onboard navigation using global positioning system data.

Advancements in Orthopedic Intervention: Retrograde Drilling and Bone Grafting of Osteochondral Lesions of the Knee Using Magnetic Resonance Imaging Guidance

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

Seebauer, Christian J., E-mail: christian.seebauer@charite.d; Bail, Hermann J., E-mail: hermann-josef.bail@klinikum-nuernberg.d; Rump, Jens C., E-mail: jens.rump@charite.de

Computer-assisted surgery is currently a novel challenge for surgeons and interventional radiologists. Magnetic resonance imaging (MRI)-guided procedures are still evolving. In this experimental study, we describe and assess an innovative passive-navigation method for MRI-guided treatment of osteochondritis dissecans of the knee. A navigation principle using a passive-navigation device was evaluated in six cadaveric knee joint specimens for potential applicability in retrograde drilling and bone grafting of osteochondral lesions using MRI guidance. Feasibility and accuracy were evaluated in an open MRI scanner (1.0 T Philips Panorama HFO MRI System). Interactive MRI navigation allowed precise drilling and bone grafting of osteochondral lesionsmore » of the knee. All lesions were hit with an accuracy of 1.86 mm in the coronal plane and 1.4 mm the sagittal plane. Targeting of all lesions was possible with a single drilling. MRI allowed excellent assessment of correct positioning of the cancellous bone cylinder during bone grafting. The navigation device and anatomic structures could be clearly identified and distinguished throughout the entire drilling procedure. MRI-assisted navigation method using a passive navigation device is feasible for the treatment of osteochondral lesions of the knee under MRI guidance and allows precise and safe drilling without exposure to ionizing radiation. This method may be a viable alternative to other navigation principles, especially for pediatric and adolescent patients. This MRI-navigated method is also potentially applicable in many other MRI-guided interventions.« less

Unraveling navigational strategies in migratory insects.

PubMed

Merlin, Christine; Heinze, Stanley; Reppert, Steven M

2012-04-01

Long-distance migration is a strategy some animals use to survive a seasonally changing environment. To reach favorable grounds, migratory animals have evolved sophisticated navigational mechanisms that rely on a map and compasses. In migratory insects, the existence of a map sense (sense of position) remains poorly understood, but recent work has provided new insights into the mechanisms some compasses use for maintaining a constant bearing during long-distance navigation. The best-studied directional strategy relies on a time-compensated sun compass, used by diurnal insects, for which neural circuits have begun to be delineated. Yet, a growing body of evidence suggests that migratory insects may also rely on other compasses that use night sky cues or the Earth's magnetic field. Those mechanisms are ripe for exploration. Copyright © 2011 Elsevier Ltd. All rights reserved.

Multicultural Personality: An Evolving Theory of Optimal Functioning in Culturally Heterogeneous Societies

ERIC Educational Resources Information Center

Ponterotto, Joseph G.

2010-01-01

The present article provides an update of the author's evolving theory of the "multicultural personality" (MP). The MP is conceptualized as a narrow matrix of personality traits or dispositions (characteristic adaptations) that can be subsumed under broad trait models of personality (e.g., Big Five). MP theory posits that its constituent factors…

As Patient Navigation Expands and Evolves, Nurses Assume Many Roles

Cancer.gov

It can be difficult to access care in our labyrinthine health care system. Oncology nurses are joining the ranks of patient navigators—a diverse group of people who help patients at all stages of cancer care, from screening and diagnosis to treatment and survivorship.

Navigation by Satellite.

ERIC Educational Resources Information Center

Visich, Marian, Jr.

Technological advances during the past few decades have revolutionized many complex systems that influence human activity. As the rate of technological progress accelerates, these systems will become more complex, and new ones will evolve. Citizens in a technological society need to be able to make intelligent choices about how technology will…

Navigating the Risky Terrain of Children's Working Theories

ERIC Educational Resources Information Center

Areljung, Sofie; Kelly-Ware, Janette

2017-01-01

"Working theories" encompass children's theorising about the social and material worlds. This article looks explicitly at power relations involved in pedagogy around children's working theories by focusing on the teacher's control of what and whose working theories get unpacked and extended. From an analysis of four cases from early…

Neural systems analysis of decision making during goal-directed navigation.

PubMed

Penner, Marsha R; Mizumori, Sheri J Y

2012-01-01

The ability to make adaptive decisions during goal-directed navigation is a fundamental and highly evolved behavior that requires continual coordination of perceptions, learning and memory processes, and the planning of behaviors. Here, a neurobiological account for such coordination is provided by integrating current literatures on spatial context analysis and decision-making. This integration includes discussions of our current understanding of the role of the hippocampal system in experience-dependent navigation, how hippocampal information comes to impact midbrain and striatal decision making systems, and finally the role of the striatum in the implementation of behaviors based on recent decisions. These discussions extend across cellular to neural systems levels of analysis. Not only are key findings described, but also fundamental organizing principles within and across neural systems, as well as between neural systems functions and behavior, are emphasized. It is suggested that studying decision making during goal-directed navigation is a powerful model for studying interactive brain systems and their mediation of complex behaviors. Copyright © 2011. Published by Elsevier Ltd.

Delta-DOR: The One-Nanoradian Navigation Measurement System of the Deep Space Network --- History, Architecture, and Componentry

NASA Astrophysics Data System (ADS)

Curkendall, D. W.; Border, J. S.

2013-05-01

Doppler and range data alone supported navigation for the earliest missions into deep space. Though extremely precise in line-of-sight coordinates, the navigation system built on these data had a weakness for determining the spacecraft declination component. To address this, the Deep Space Network (DSN) developed the capability for very long baseline interferometry measurements beginning in the late 1970s. Both the implementation of the interferometric system and the importance of such measurements to flight projects have evolved significantly over the past three decades. Innovations introduced through research and development programs have led to continuous improvements in performance. Today's system provides data approaching one-nanoradian accuracy with reliability of 98 percent. This article provides an overview of the development and use of interferometric tracking techniques in the DSN starting with the Viking era and continuing with a description of the current system and its planned use to support interplanetary cruise navigation of the Mars Science Laboratory spacecraft.

Integrated navigation fusion strategy of INS/UWB for indoor carrier attitude angle and position synchronous tracking.

PubMed

Fan, Qigao; Wu, Yaheng; Hui, Jing; Wu, Lei; Yu, Zhenzhong; Zhou, Lijuan

2014-01-01

In some GPS failure conditions, positioning for mobile target is difficult. This paper proposed a new method based on INS/UWB for attitude angle and position synchronous tracking of indoor carrier. Firstly, error model of INS/UWB integrated system is built, including error equation of INS and UWB. And combined filtering model of INS/UWB is researched. Simulation results show that the two subsystems are complementary. Secondly, integrated navigation data fusion strategy of INS/UWB based on Kalman filtering theory is proposed. Simulation results show that FAKF method is better than the conventional Kalman filtering. Finally, an indoor experiment platform is established to verify the integrated navigation theory of INS/UWB, which is geared to the needs of coal mine working environment. Static and dynamic positioning results show that the INS/UWB integrated navigation system is stable and real-time, positioning precision meets the requirements of working condition and is better than any independent subsystem.

Envisioning a New Foundation for Gifted Education: Evolving Complexity Theory (ECT) of Talent Development

ERIC Educational Resources Information Center

Dai, David Yun

2017-01-01

This article presents a new theory of talent development, evolving complexity theory (ECT), in the context of the changing theoretical directions as well as the landscape of gifted education. I argue that gifted education needs a new foundation that provides a broad psychosocial basis than what the notion of giftedness can afford. A focus on…

Shape shifting: Local landmarks interfere with navigation by, and recognition of, global shape.

PubMed

Buckley, Matthew G; Smith, Alastair D; Haselgrove, Mark

2014-03-01

An influential theory of spatial navigation states that the boundary shape of an environment is preferentially encoded over and above other spatial cues, such that it is impervious to interference from alternative sources of information. We explored this claim with 3 intradimensional-extradimensional shift experiments, designed to examine the interaction of landmark and geometric features of the environment in a virtual navigation task. In Experiments 1 and 2, participants were first required to find a hidden goal using information provided by the shape of the arena or landmarks integrated into the arena boundary (Experiment 1) or within the arena itself (Experiment 2). Participants were then transferred to a different-shaped arena that contained novel landmarks and were again required to find a hidden goal. In both experiments, participants who were navigating on the basis of cues that were from the same dimension that was previously relevant (intradimensional shift) learned to find the goal significantly faster than participants who were navigating on the basis of cues that were from a dimension that was previously irrelevant (extradimensional shift). This suggests that shape information does not hold special status when learning about an environment. Experiment 3 replicated Experiment 2 and also assessed participants' recognition of the global shape of the navigated arenas. Recognition was attenuated when landmarks were relevant to navigation throughout the experiment. The results of these experiments are discussed in terms of associative and non-associative theories of spatial learning.

Influence of a screening navigation program on social inequalities in health beliefs about colorectal cancer screening.

PubMed

Vallet, Fanny; Guillaume, Elodie; Dejardin, Olivier; Guittet, Lydia; Bouvier, Véronique; Mignon, Astrid; Berchi, Célia; Salinas, Agnès; Launoy, Guy; Christophe, Véronique

2016-08-01

The aim of the study was to test whether a screening navigation program leads to more favorable health beliefs and decreases social inequalities in them. The selected 261 noncompliant participants in a screening navigation versus a usual screening program arm had to respond to health belief measures inspired by the Protection Motivation Theory. Regression analyses showed that social inequalities in perceived efficacy of screening, favorable attitude, and perceived facility were reduced in the screening navigation compared to the usual screening program. These results highlight the importance of health beliefs to understand the mechanism of screening navigation programs in reducing social inequalities. © The Author(s) 2014.

Developing Leaders through Mentoring: A Brief Literature Review

ERIC Educational Resources Information Center

Leavitt, Carol C.

2011-01-01

Our rapidly-changing, ambiguous, global business arena demands a unique and evolving set of insights and capabilities by which leaders may effectively navigate this new terrain. Mentoring can accomplish exactly that, as its processes orient, train, and advance the skills, knowledge, and experiences of aspiring leaders. Best utilized, mentoring is…

Navigating the Complexity of Qualitative Research in Postmodern Contexts: Assemblage, Critical Reflexivity, and Communion as Guides

ERIC Educational Resources Information Center

Bettez, Silvia Cristina

2015-01-01

For graduate students and other emerging qualitative researchers, the ever-evolving and sometimes conflicting perspectives, methodologies, and practices within various post-positivist frameworks (e.g. feminist, critical, Indigenous, participatory) can be overwhelming. Qualitative researchers working within postmodern contexts of multiplicity and…

The Brussels Metro: Accessibility through Collaboration

ERIC Educational Resources Information Center

Strickfaden, Megan; Devlieger, Patrick

2011-01-01

This article describes and analyzes the development of a navigation and orientation system for people with visual impairments as it evolved over three decades. It includes reflections on how users have been involved in the redesign process and illustrates how people with and without disabilities have collaborated to create a more suitable and…

Factors for Successful Evolution and Sustainability of Quality Distance Education

ERIC Educational Resources Information Center

Angolia, Mark G.; Pagliari, Leslie R.

2016-01-01

Distance education (DE) is entering its fourth generation, requiring universities to consider how to sustain this continually evolving delivery method. Competition from for-profit entities, open-source depositories, and an increasing number of non-profit universities has created a competitive marketplace for academia to navigate. Rather than…

Navigation Performance of Global Navigation Satellite Systems in the Space Service Volume

NASA Technical Reports Server (NTRS)

Force, Dale A.

2013-01-01

This paper extends the results I reported at this year's ION International Technical Meeting on multi-constellation GNSS coverage by showing how the use of multi-constellation GNSS improves Geometric Dilution of Precision (GDOP). Originally developed to provide position, navigation, and timing for terrestrial users, GPS has found increasing use for in space for precision orbit determination, precise time synchronization, real-time spacecraft navigation, and three-axis attitude control of Earth orbiting satellites. With additional Global Navigation Satellite Systems (GNSS) coming into service (GLONASS, Galileo, and Beidou) and the development of Satellite Based Augmentation Services, it is possible to obtain improved precision by using evolving multi-constellation receiver. The Space Service Volume formally defined as the volume of space between three thousand kilometers altitude and geosynchronous altitude ((is) approximately 36,500 km), with the volume below three thousand kilometers defined as the Terrestrial Service Volume (TSV). The USA has established signal requirements for the Space Service Volume (SSV) as part of the GPS Capability Development Documentation (CDD). Diplomatic efforts are underway to extend Space service Volume commitments to the other Position, Navigation, and Timing (PNT) service providers in an effort to assure that all space users will benefit from the enhanced capabilities of interoperating GNSS services in the space domain.

A Sustained Proximity Network for Multi-Mission Lunar Exploration

NASA Technical Reports Server (NTRS)

Soloff, Jason A.; Noreen, Gary; Deutsch, Leslie; Israel, David

2005-01-01

Tbe Vision for Space Exploration calls for an aggressive sequence of robotic missions beginning in 2008 to prepare for a human return to the Moon by 2020, with the goal of establishing a sustained human presence beyond low Earth orbit. A key enabler of exploration is reliable, available communication and navigation capabilities to support both human and robotic missions. An adaptable, sustainable communication and navigation architecture has been developed by Goddard Space Flight Center and the Jet Propulsion Laboratory to support human and robotic lunar exploration through the next two decades. A key component of the architecture is scalable deployment, with the infrastructure evolving as needs emerge, allowing NASA and its partner agencies to deploy an interoperable communication and navigation system in an evolutionary way, enabling cost effective, highly adaptable systems throughout the lunar exploration program.

Sperm as microswimmers - navigation and sensing at the physical limit

NASA Astrophysics Data System (ADS)

Kaupp, Ulrich B.; Alvarez, Luis

2016-11-01

Many cells and microorganisms have evolved a motility apparatus to explore their surroundings. For guidance, these biological microswimmers rely on physical and chemical cues that are transduced by cellular pathways into directed movement - a process called taxis. Only few biological microswimmers have been studied as detailed as sperm from sea urchins. Sperm and eggs are released into the seawater. To enhance the chances of fertilization, eggs release chemical factors - called chemoattractants - that establish a chemical gradient and, thereby, guide sperm to the egg. Sea urchin sperm constitute a unique model system for understanding cell navigation at every level: from molecules to cell behaviours. We will outline the chemotactic signalling pathway of sperm from the sea urchin Arbacia punctulata and discuss how signalling controls navigation in a chemical gradient. Finally, we discuss recent insights into sperm chemotaxis in three dimensions (3D).

Kilohoku Ho`okele Wa`a : Astronomy of the Hawaiian Navigators

NASA Astrophysics Data System (ADS)

Slater, Stephanie; Slater, Timothy F.; Baybayan, Kalepa C.

2016-01-01

This poster provides an introduction to the astronomy of the Hawaiian wayfinders, Kilohoku Ho`okele Wa`a. Rooted in a legacy of navigation across the Polynesian triangle, wayfinding astronomy has been part of a suite of skills that allows navigators to deliberately hop between the small islands of the Pacific, for thousands of years. Forty years ago, in one manifestation of the Hawaiian Renaissance, our teachers demonstrated that ancient Hawaiians were capable of traversing the wide Pacific to settle and trade on islands separated by thousands of miles. Today those same mentors train a new generation of navigators, making Hawaiian voyaging a living, evolving, sustainable endeavor. This poster presents two components of astronomical knowledge that all crewmen, but particularly those in training to become navigators, learn early in their training. Na Ohana Hoku, the Hawaiian Star Families constitute the basic units of the Hawaiian sky. In contrast to the Western system of 88 constellations, Na Ohana Hoku divides the sky into four sections that each run from the northern to the southern poles. This configuration reduces cognitive load, allowing the navigator to preserve working memory for other complex tasks. In addition, these configurations of stars support the navigator in finding and generatively using hundreds of individual, and navigationally important pairs of stars. The Hawaiian Star Compass divides the celestial sphere into a directional system that uses 32 rather than 8 cardinal points. Within the tropics, the rising and setting of celestial objects are consistent within the Hawaiian Star Compass, providing for extremely reliable direction finding. Together, Na Ohana Hoku and the Hawaiian Star Compass provide the tropical navigator with astronomical assistance that is not available to, and would have been unknown to Western navigators trained at higher latitudes.

Book Review: Earth's Magnetism in the Age of Sail. A.R.T. Jonkers, The Johns Hopkins University Press, Baltimore, London, 300 pp., ISBN 0-8018-7132-8, 2003, $45 (£35)

NASA Astrophysics Data System (ADS)

Love, J. J.

2004-12-01

For many centuries, the source, behavior, and even the essential nature of geomagnetism were enigmatic. Despite this, the effect of geomagnetism was familiar, by imparting a directional preference on the magnetized needle of the compass and providing a useful, if somewhat annoyingly complicated, reference for navigators. Although the compass seems to have first been invented in China, it was the Europeans who made the most systematic early studies of magnetism, who made the first elaborate and practical usage of the compass, and who developed most of the early theories as to the cause of the compass needle's north-seeking tendency. From the centuries of the Middle Ages, through the late 16th century of the Renaissance, to the 17th century of philosophical enlightenment and the 18th century of discovery, the subject of magnetism and, more specifically, geomagnetism, evolved from a hodgepodge of mystical beliefs into something that we can today recognize as the object of modern scientific pursuit. Those same centuries witnessed the great transoceanic sailing voyages undertaken by European nations for reasons of exploration, territorial claim, religious mission, and mercantile trade. Naturally, the navigator's compass, and therefore geomagnetism, played an important role in these developments. This romantic intersection of science and history is the subject of Earth's Magnetism in the Age of Sail, a pleasantly written and scholarly book by A.R.T. Jonkers.

Visual orientation and navigation in nocturnal arthropods.

PubMed

Warrant, Eric; Dacke, Marie

2010-01-01

With their highly sensitive visual systems, the arthropods have evolved a remarkable capacity to orient and navigate at night. Whereas some navigate under the open sky, and take full advantage of the celestial cues available there, others navigate in more difficult conditions, such as through the dense understory of a tropical rainforest. Four major classes of orientation are performed by arthropods at night, some of which involve true navigation (i.e. travel to a distant goal that lies beyond the range of direct sensory contact): (1) simple straight-line orientation, typically for escape purposes; (2) nightly short-distance movements relative to a shoreline, typically in the context of feeding; (3) long-distance nocturnal migration at high altitude in the quest to locate favorable feeding or breeding sites, and (4) nocturnal excursions to and from a fixed nest or food site (i.e. homing), a task that in most species involves path integration and/or the learning and recollection of visual landmarks. These four classes of orientation--and their visual basis--are reviewed here, with special emphasis given to the best-understood animal systems that are representative of each. 2010 S. Karger AG, Basel.

Gravity

NASA Astrophysics Data System (ADS)

Poisson, Eric; Will, Clifford M.

2014-05-01

Preface; 1. Foundations of Newtonian gravity; 2. Structure of self-gravitating bodies; 3. Newtonian orbital dynamics; 4. Minkowski spacetime; 5. Curved spacetime; 6. Post-Minkowskian theory: formulation; 7. Post-Minkowskian theory: implementation; 8. Post-Newtonian theory: fundamentals; 9. Post-Newtonian theory: system of isolated bodies; 10. Post-Newtonian celestial mechanics, astrometry and navigation; 11. Gravitational waves; 12. Radiative losses and radiation reaction; 13. Alternative theories of gravity; References; Index.

Organizational Theory and Leadership Navigation

ERIC Educational Resources Information Center

Brazer, S. David; Kruse, Sharon D.; Conley, Sharon

2014-01-01

Teaching organizational theory in a way that bridges to leadership practice is vital to preparing deft educational leaders who understand the organizational behavior of schools and districts. Organizational theory guides understanding of the complexities of schools and districts and can be a basis for collaborative and effective decision making.…

Investigation of Air Transportation Technology at Ohio University, 1989-1990

NASA Technical Reports Server (NTRS)

Lilley, Robert W.

1990-01-01

The activities of the participants in the Joint University Program (JUP) at Ohio University are briefly surveyed. During 1989 to 1990, five topics received emphasis. A spectrum-efficient weather data uplink system was designed, constructed, and flight tested. An integrated Global Positioning System/Inertial Navigation System (GPS/INS) study continued, utilizing the Redundant strapdown Inertial Measurement Unit (IMU) on loan from NASA. The Ridge Regression theory was refined and applied to air navigation scenarios. System Identification theory was applied to GPS data to point the way to better understanding of the effects of Selective Availability on civilian users of this navigation system. An analysis of thought-related (electroencephalographic) signals for application to control of computer systems that could have significance in aiding paraplegics or for hands-off systems control in industrial or air traffic control areas was carried out.

What Are Punishment and Reputation for?

PubMed Central

Krasnow, Max M.; Cosmides, Leda; Pedersen, Eric J.; Tooby, John

2012-01-01

Why did punishment and the use of reputation evolve in humans? According to one family of theories, they evolved to support the maintenance of cooperative group norms; according to another, they evolved to enhance personal gains from cooperation. Current behavioral data are consistent with both hypotheses (and both selection pressures could have shaped human cooperative psychology). However, these hypotheses lead to sharply divergent behavioral predictions in circumstances that have not yet been tested. Here we report results testing these rival predictions. In every test where social exchange theory and group norm maintenance theory made different predictions, subject behavior violated the predictions of group norm maintenance theory and matched those of social exchange theory. Subjects do not direct punishment toward those with reputations for norm violation per se; instead, they use reputation self-beneficially, as a cue to lower the risk that they personally will experience losses from defection. More tellingly, subjects direct their cooperative efforts preferentially towards defectors they have punished and away from those they haven’t punished; they avoid expending punitive effort on reforming defectors who only pose a risk to others. These results are not consistent with the hypothesis that the psychology of punishment evolved to uphold group norms. The circumstances in which punishment is deployed and withheld–its circuit logic–support the hypothesis that it is generated by psychological mechanisms that evolved to benefit the punisher, by allowing him to bargain for better treatment. PMID:23049833

What are punishment and reputation for?

PubMed

Krasnow, Max M; Cosmides, Leda; Pedersen, Eric J; Tooby, John

2012-01-01

Why did punishment and the use of reputation evolve in humans? According to one family of theories, they evolved to support the maintenance of cooperative group norms; according to another, they evolved to enhance personal gains from cooperation. Current behavioral data are consistent with both hypotheses (and both selection pressures could have shaped human cooperative psychology). However, these hypotheses lead to sharply divergent behavioral predictions in circumstances that have not yet been tested. Here we report results testing these rival predictions. In every test where social exchange theory and group norm maintenance theory made different predictions, subject behavior violated the predictions of group norm maintenance theory and matched those of social exchange theory. Subjects do not direct punishment toward those with reputations for norm violation per se; instead, they use reputation self-beneficially, as a cue to lower the risk that they personally will experience losses from defection. More tellingly, subjects direct their cooperative efforts preferentially towards defectors they have punished and away from those they haven't punished; they avoid expending punitive effort on reforming defectors who only pose a risk to others. These results are not consistent with the hypothesis that the psychology of punishment evolved to uphold group norms. The circumstances in which punishment is deployed and withheld-its circuit logic-support the hypothesis that it is generated by psychological mechanisms that evolved to benefit the punisher, by allowing him to bargain for better treatment.

The attribution of success when using navigation aids.

PubMed

Brown, Michael; Houghton, Robert; Sharples, Sarah; Morley, Jeremy

2015-01-01

Attitudes towards geographic information technology is a seldom explored research area that can be explained with reference to established theories of attribution. This article reports on a study of how the attribution of success and failure in pedestrian navigation varies with level of automation, degree of success and locus of control. A total of 113 participants took part in a survey exploring reflections on personal experiences and vignettes describing fictional navigation experiences. A complex relationship was discovered in which success tends to be attributed to skill and failure to the navigation aid when participants describe their own experiences. A reversed pattern of results was found when discussing the navigation of others. It was also found that navigation success and failure are associated with personal skill to a greater extent when using paper maps, as compared with web-based routing engines or satellite navigation systems. This article explores the influences on the attribution of success and failure when using navigation aids. A survey was performed exploring interpretations of navigation experiences. Level of success, self or other as navigator and type of navigation aid used are all found to influence the attribution of outcomes to internal or external factors.

The attribution of success when using navigation aids

PubMed Central

Brown, Michael; Houghton, Robert; Sharples, Sarah; Morley, Jeremy

2015-01-01

Attitudes towards geographic information technology is a seldom explored research area that can be explained with reference to established theories of attribution. This article reports on a study of how the attribution of success and failure in pedestrian navigation varies with level of automation, degree of success and locus of control. A total of 113 participants took part in a survey exploring reflections on personal experiences and vignettes describing fictional navigation experiences. A complex relationship was discovered in which success tends to be attributed to skill and failure to the navigation aid when participants describe their own experiences. A reversed pattern of results was found when discussing the navigation of others. It was also found that navigation success and failure are associated with personal skill to a greater extent when using paper maps, as compared with web-based routing engines or satellite navigation systems. Practitioner Summary: This article explores the influences on the attribution of success and failure when using navigation aids. A survey was performed exploring interpretations of navigation experiences. Level of success, self or other as navigator and type of navigation aid used are all found to influence the attribution of outcomes to internal or external factors. PMID:25384842

Collective animal navigation and migratory culture: from theoretical models to empirical evidence

PubMed Central

Dell, Anthony I.

2018-01-01

Animals often travel in groups, and their navigational decisions can be influenced by social interactions. Both theory and empirical observations suggest that such collective navigation can result in individuals improving their ability to find their way and could be one of the key benefits of sociality for these species. Here, we provide an overview of the potential mechanisms underlying collective navigation, review the known, and supposed, empirical evidence for such behaviour and highlight interesting directions for future research. We further explore how both social and collective learning during group navigation could lead to the accumulation of knowledge at the population level, resulting in the emergence of migratory culture. This article is part of the theme issue ‘Collective movement ecology’. PMID:29581394

Integrated polarization-dependent sensor for autonomous navigation

NASA Astrophysics Data System (ADS)

Liu, Ze; Zhang, Ran; Wang, Zhiwen; Guan, Le; Li, Bin; Chu, Jinkui

2015-01-01

Based on the navigation strategy of insects utilizing the polarized skylight, an integrated polarization-dependent sensor for autonomous navigation is presented. The navigation sensor has the features of compact structure, high precision, strong robustness, and a simple manufacture technique. The sensor is composed by integrating a complementary-metal-oxide-semiconductor sensor with a multiorientation nanowire grid polarizer. By nanoimprint lithography, the multiorientation nanowire polarizer is fabricated in one step and the alignment error is eliminated. The statistical theory is added to the interval-division algorithm to calculate the polarization angle of the incident light. The laboratory and outdoor tests for the navigation sensor are implemented and the errors of the measured angle are ±0.02 deg and ±1.3 deg, respectively. The results show that the proposed sensor has potential for application in autonomous navigation.

Navigable networks as Nash equilibria of navigation games.

PubMed

Gulyás, András; Bíró, József J; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

2015-07-03

Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network.

Online History-Keeping for Outreach and Community Development

ERIC Educational Resources Information Center

Huwe, Terence K.

2010-01-01

The rapidly evolving digital world inspires much use of nautical terminology: (1) navigation; (2) discovery; (3) the voyage; and (4) the new terrain at the end of the journey. Considering how quickly new technologies are arriving on smartphones, the nautical adventure is continuing at an increased pace. Innovations in basic library services follow…

Institutional v. Technical Environments: Reconciling the Goals of Decentralization in an Evolving Charter School Organization

ERIC Educational Resources Information Center

Huerta, Luis A.

2009-01-01

This article analyzes how macrolevel institutional forces persist and limit the expansion of decentralized schools that attempt to challenge normative definitions and practices of traditional school organizations. Using qualitative case study methodology, the analysis focuses on how one decentralized charter school navigated and reconciled its…

E-Learning 2010: E-Educators Evolving

ERIC Educational Resources Information Center

Bushweller, Kevin, Ed.

2010-01-01

This special report, the second in a three-part series on e-learning, aims to answer questions related to the growing role of e-educators in K-12 education. It provides perspectives and advice from state policymakers and virtual school providers navigating through the new and often murky policy waters of online-only education, and features…

The Brave New World of Strategic Enrollment Management

ERIC Educational Resources Information Center

Bontrager, Bob

2007-01-01

The practice of strategic enrollment management (SEM) can be likened to navigating a ship through uncharted waters. Dating back to the 1970s, the very concept of enrollment management came into being and has since evolved in the face of a steady progression of daunting challenges requiring repeated course corrections. A massive demographic…

Shape Shifting: Local Landmarks Interfere with Navigation By, and Recognition Of, Global Shape

ERIC Educational Resources Information Center

Buckley, Matthew G.; Smith, Alastair D.; Haselgrove, Mark

2014-01-01

An influential theory of spatial navigation states that the boundary shape of an environment is preferentially encoded over and above other spatial cues, such that it is impervious to interference from alternative sources of information. We explored this claim with 3 intradimensional--extradimensional shift experiments, designed to examine the…

Kilohoku Ho`okele Wa`a : Astronomy of the Modern Hawaiian Wayfinders

NASA Astrophysics Data System (ADS)

Ha`o, Celeste; Dye, Ahia G.; Slater, Stephanie J.; Slater, Timothy F.; Baybayan, Kalepa

2015-08-01

This paper provides an introduction to Kilohoku Ho`okele Wa`a, the astronomy of the Hawaiian wayfinders. Rooted in a legacy of navigation across the Polynesian triangle, wayfinding astronomy has been part of a suite of skills that allows navigators to deliberately hop between the small islands of the Pacific, for thousands of years. Forty years ago, in one manifestation of the Hawaiian Renaissance, our teachers demonstrated that ancient Hawaiians were capable of traversing the wide Pacific to settle and trade on islands separated by thousands of miles. Today those same mentors train a new generation of navigators, making Hawaiian voyaging a living, evolving, sustainable endeavor. This paper presents two components of astronomical knowledge that all crewmen, but particularly those in training to become navigators, learn early in their training. Na Ohana Hoku, the Hawaiian Star Families constitute the basic units of the Hawaiian sky. In contrast to the Western system of 88 constellations, Na Ohana Hoku divides the sky into four sections that each run from the northern to the southern poles. This configuration reduces cognitive load, allowing the navigator to preserve working memory for other complex tasks. In addition, these configurations of stars support the navigator in finding and generatively using hundreds of individual, and navigationally important pairs of stars. The Hawaiian Star Compass divides the celestial sphere into a directional system that uses 32 rather than 8 cardinal points. Within the tropics, the rising and setting of celestial objects are consistent within the Hawaiian Star Compass, providing for extremely reliable direction finding. Together, Na Ohana Hoku and the Hawaiian Star Compass provide the tropical navigator with astronomical assistance that is not available to, and would have been unknown to Western navigators trained at higher latitudes.

GPS free navigation inspired by insects through monocular camera and inertial sensors

NASA Astrophysics Data System (ADS)

Liu, Yi; Liu, J. G.; Cao, H.; Huang, Y.

2015-12-01

Navigation without GPS and other knowledge of environment have been studied for many decades. Advance technology have made sensors more compact and subtle that can be easily integrated into micro and hand-hold device. Recently researchers found that bee and fruit fly have an effectively and efficiently navigation mechanism through optical flow information and process only with their miniature brain. We present a navigation system inspired by the study of insects through a calibrated camera and other inertial sensors. The system utilizes SLAM theory and can be worked in many GPS denied environment. Simulation and experimental results are presented for validation and quantification.

Enabling Communication and Navigation Technologies for Future Near Earth Science Missions

NASA Technical Reports Server (NTRS)

Israel, David J.; Heckler, Greg; Menrad, Robert J.; Hudiburg, John J.; Boroson, Don M.; Robinson, Bryan S.; Cornwell, Donald M.

2016-01-01

In 2015, the Earth Regimes Network Evolution Study (ERNESt) Team proposed a fundamentally new architectural concept, with enabling technologies, that defines an evolutionary pathway out to the 2040 timeframe in which an increasing user community comprised of more diverse space science and exploration missions can be supported. The architectural concept evolves the current instantiations of the Near Earth Network and Space Network through implementation of select technologies resulting in a global communication and navigation network that provides communication and navigation services to a wide range of space users in the Near Earth regime, defined as an Earth-centered sphere with radius of 2M Km. The enabling technologies include: High Rate Optical Communications, Optical Multiple Access (OMA), Delay Tolerant Networking (DTN), User Initiated Services (UIS), and advanced Position, Navigation, and Timing technology (PNT). This paper describes this new architecture, the key technologies that enable it and their current technology readiness levels. Examples of science missions that could be enabled by the technologies and the projected operational benefits of the architecture concept to missions are also described.

Expanding Hardware-in-the-Loop Formation Navigation and Control with Radio Frequency Crosslink Ranging

NASA Technical Reports Server (NTRS)

Mitchell, Jason W.; Barbee, Brent W.; Baldwin, Philip J.; Luquette, Richard J.

2007-01-01

The Formation Flying Testbed (FFTB) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) provides a hardware-in-the-loop test environment for formation navigation and control. The facility continues to evolve as a modular, hybrid, dynamic simulation facility for end-to-end guidance, navigation, and control (GN&C) design and analysis of formation flying spacecraft. The core capabilities of the FFTB, as a platform for testing critical hardware and software algorithms in-the-loop, are reviewed with a focus on recent improvements. With the most recent improvement, in support of Technology Readiness Level (TRL) 6 testing of the Inter-spacecraft Ranging and Alarm System (IRAS) for the Magnetospheric Multiscale (MMS) mission, the FFTB has significantly expanded its ability to perform realistic simulations that require Radio Frequency (RF) ranging sensors for relative navigation with the Path Emulator for RF Signals (PERFS). The PERFS, currently under development at NASA GSFC, modulates RF signals exchanged between spacecraft. The RF signals are modified to accurately reflect the dynamic environment through which they travel, including the effects of medium, moving platforms, and radiated power.

Evolving Systems and Adaptive Key Component Control

NASA Technical Reports Server (NTRS)

Frost, Susan A.; Balas, Mark J.

2009-01-01

We propose a new framework called Evolving Systems to describe the self-assembly, or autonomous assembly, of actively controlled dynamical subsystems into an Evolved System with a higher purpose. An introduction to Evolving Systems and exploration of the essential topics of the control and stability properties of Evolving Systems is provided. This chapter defines a framework for Evolving Systems, develops theory and control solutions for fundamental characteristics of Evolving Systems, and provides illustrative examples of Evolving Systems and their control with adaptive key component controllers.

Navigable networks as Nash equilibria of navigation games

PubMed Central

Gulyás, András; Bíró, József J.; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

2015-01-01

Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network. PMID:26138277

Performance analysis of device-level SINS/ACFSS deeply integrated navigation method

NASA Astrophysics Data System (ADS)

Zhang, Hao; Qin, Shiqiao; Wang, Xingshu; Jiang, Guangwen; Tan, Wenfeng

2016-10-01

The Strap-Down Inertial Navigation System (SINS) is a widely used navigation system. The combination of SINS and the Celestial Navigation System (CNS) is one of the popular measures to constitute the integrated navigation system. A Star Sensor (SS) is used as a precise attitude determination device in CNS. To solve the problem that the star image obtained by SS under dynamic conditions is motion-blurred, the Attitude Correlated Frames (ACF) is presented and the star sensor which works based on ACF approach is named ACFSS. Depending on the ACF approach, a novel device-level SINS/ACFSS deeply integrated navigation method is proposed in this paper. Feedback to the ACF process from the error of the gyro is one of the typical characters of the SINS/CNS deeply integrated navigation method. Herein, simulation results have verified its validity and efficiency in improving the accuracy of gyro and it can be proved that this method is feasible in theory.

Visual Hemispheric Specialization: A Computational Theory. Technical Report #7.

ERIC Educational Resources Information Center

Kosslyn, Stephen M.

Visual recognition, navigation, tracking, and imagery are posited to involve some of the same types of representations and processes. The first part of this paper develops a theory of some of the shared types of representations and processing modules. The theory is developed in light of neurophysiological and neuroanatomical data from non-human…

The Evolutional History of Electromagnetic Navigation Bronchoscopy: State of the Art.

PubMed

Mehta, Atul C; Hood, Kristin L; Schwarz, Yehuda; Solomon, Stephen B

2018-04-30

Electromagnetic navigation bronchoscopy (ENB) has come a long way from the early roots of electromagnetic theory. Current ENB devices have the potential to change the way lung cancer is detected and treated. This paper provides an overview of the history, current state, and future of ENB. Copyright © 2018. Published by Elsevier Inc.

How One Exceptional Teacher Navigated Her Working Environment as the Teacher of a Marginal Subject

ERIC Educational Resources Information Center

Lux, Karen; McCullick, Bryan A.

2011-01-01

The purpose of this study was to analyze how one exceptional elementary physical education teacher navigated her working environment as the teacher of a marginal subject. Structuration Theory (Giddens, 1984) was used to make meaning of how the teacher functioned within her school community allowing her to remain motivated and effective. Data…

Agency Construction and Navigation in Oral Narratives of English Learning by Chinese College English Majors

ERIC Educational Resources Information Center

Lin, Qiuming

2017-01-01

The current study aims to investigate the discursive construction and navigation of agency in oral narratives of English learning by Chinese college English majors. Based on the theoretical framework integrating Bamberg et. al.'s theory of identity dilemma and Hallidayan systemic functional linguistics, the study has addressed two research…

Have Sex Differences in Spatial Ability Evolved from Male Competition for Mating and Female Concern for Survival?

ERIC Educational Resources Information Center

Ecuyer-Dab, Isabelle; Robert, Michele

2004-01-01

Drawing on the theoretical and empirical foundations of two evolutionary models, we argue that, among humans and other mammals, a twofold selection process would parsimoniously account for sex-linked advantages in spatial contexts. In males, a superiority for both solving navigation-related spatial problems and understanding physical principles…

The evolving Planck mass in classically scale-invariant theories

NASA Astrophysics Data System (ADS)

Kannike, K.; Raidal, M.; Spethmann, C.; Veermäe, H.

2017-04-01

We consider classically scale-invariant theories with non-minimally coupled scalar fields, where the Planck mass and the hierarchy of physical scales are dynamically generated. The classical theories possess a fixed point, where scale invariance is spontaneously broken. In these theories, however, the Planck mass becomes unstable in the presence of explicit sources of scale invariance breaking, such as non-relativistic matter and cosmological constant terms. We quantify the constraints on such classical models from Big Bang Nucleosynthesis that lead to an upper bound on the non-minimal coupling and require trans-Planckian field values. We show that quantum corrections to the scalar potential can stabilise the fixed point close to the minimum of the Coleman-Weinberg potential. The time-averaged motion of the evolving fixed point is strongly suppressed, thus the limits on the evolving gravitational constant from Big Bang Nucleosynthesis and other measurements do not presently constrain this class of theories. Field oscillations around the fixed point, if not damped, contribute to the dark matter density of the Universe.

Spatial navigation, episodic memory, episodic future thinking, and theory of mind in children with autism spectrum disorder: evidence for impairments in mental simulation?

PubMed Central

Lind, Sophie E.; Bowler, Dermot M.; Raber, Jacob

2014-01-01

This study explored spatial navigation alongside several other cognitive abilities that are thought to share common underlying neurocognitive mechanisms (e.g., the capacity for self-projection, scene construction, or mental simulation), and which we hypothesized may be impaired in autism spectrum disorder (ASD). Twenty intellectually high-functioning children with ASD (with a mean age of ~8 years) were compared to 20 sex, age, IQ, and language ability matched typically developing children on a series of tasks to assess spatial navigation, episodic memory, episodic future thinking (also known as episodic foresight or prospection), theory of mind (ToM), relational memory, and central coherence. This is the first study to explore these abilities concurrently within the same sample. Spatial navigation was assessed using the “memory island” task, which involves finding objects within a realistic, computer simulated, three-dimensional environment. Episodic memory and episodic future thinking were assessed using a past and future event description task. ToM was assessed using the “animations” task, in which children were asked to describe the interactions between two animated triangles. Relational memory was assessed using a recognition task involving memory for items (line drawings), patterned backgrounds, or combinations of items and backgrounds. Central coherence was assessed by exploring differences in performance across segmented and unsegmented versions of block design. Children with ASD were found to show impairments in spatial navigation, episodic memory, episodic future thinking, and central coherence, but not ToM or relational memory. Among children with ASD, spatial navigation was found to be significantly negatively related to the number of repetitive behaviors. In other words, children who showed more repetitive behaviors showed poorer spatial navigation. The theoretical and practical implications of the results are discussed. PMID:25538661

Spatial navigation, episodic memory, episodic future thinking, and theory of mind in children with autism spectrum disorder: evidence for impairments in mental simulation?

PubMed

Lind, Sophie E; Bowler, Dermot M; Raber, Jacob

2014-01-01

This study explored spatial navigation alongside several other cognitive abilities that are thought to share common underlying neurocognitive mechanisms (e.g., the capacity for self-projection, scene construction, or mental simulation), and which we hypothesized may be impaired in autism spectrum disorder (ASD). Twenty intellectually high-functioning children with ASD (with a mean age of ~8 years) were compared to 20 sex, age, IQ, and language ability matched typically developing children on a series of tasks to assess spatial navigation, episodic memory, episodic future thinking (also known as episodic foresight or prospection), theory of mind (ToM), relational memory, and central coherence. This is the first study to explore these abilities concurrently within the same sample. Spatial navigation was assessed using the "memory island" task, which involves finding objects within a realistic, computer simulated, three-dimensional environment. Episodic memory and episodic future thinking were assessed using a past and future event description task. ToM was assessed using the "animations" task, in which children were asked to describe the interactions between two animated triangles. Relational memory was assessed using a recognition task involving memory for items (line drawings), patterned backgrounds, or combinations of items and backgrounds. Central coherence was assessed by exploring differences in performance across segmented and unsegmented versions of block design. Children with ASD were found to show impairments in spatial navigation, episodic memory, episodic future thinking, and central coherence, but not ToM or relational memory. Among children with ASD, spatial navigation was found to be significantly negatively related to the number of repetitive behaviors. In other words, children who showed more repetitive behaviors showed poorer spatial navigation. The theoretical and practical implications of the results are discussed.

Does intraoperative navigation improve the accuracy of mandibular angle osteotomy: Comparison between augmented reality navigation, individualised templates and free-hand techniques.

PubMed

Zhu, Ming; Liu, Fei; Zhou, Chaozheng; Lin, Li; Zhang, Yan; Chai, Gang; Xie, Le; Qi, Fazhi; Li, Qingfeng

2018-04-11

Augmented reality (AR)-based navigation surgery has evolved to be an advanced assisted technology. The aim of this study is to manifest the accuracy of AR navigation for the intraoperative mandibular angle osteotomy by comparing the navigation with other interventional techniques. A retrospective study was conducted with 93 post-surgical patients with mandibular angle hypertrophy admitted at our plastic and reconstructive surgery department between September 2011 and June 2016. Thirty-one patients received osteotomy conducted using a navigation system based on augmented reality (AR group), 28 patients received osteotomy conducted using individualised templates (IT group) and the remaining 34 patients received osteotomy performed by free hand (free-hand group). The post-operative computed tomography (CT) images were reviewed and analysed by comparing with pre-surgical planning generated by three-dimensional (3D) software. The preparation time, cutting time, whole operating time and discrepancy in osteotomy lines were measured. The preparation time was much shorter for the free-hand group than that for the AR group and the IT group (P < 0.01). However, no significant difference in the whole operating time was observed among the three groups (P > 0.05). In addition, the discrepancy in osteotomy lines was lower for the AR group and in the IT group than for the free-hand group (P < 0.01). The navigation system based on AR has a higher accuracy, more reliability and better user friendliness for some particular clinical procedures than for other techniques, which has a promising clinical prospect. Copyright © 2018. Published by Elsevier Ltd.

The Evolution of Computer-Assisted Total Hip Arthroplasty and Relevant Applications.

PubMed

Chang, Jun-Dong; Kim, In-Sung; Bhardwaj, Atul M; Badami, Ramachandra N

2017-03-01

In total hip arthroplasty (THA), the accurate positioning of implants is the key to achieve a good clinical outcome. Computer-assisted orthopaedic surgery (CAOS) has been developed for more accurate positioning of implants during the THA. There are passive, semi-active, and active systems in CAOS for THA. Navigation is a passive system that only provides information and guidance to the surgeon. There are 3 types of navigation: imageless navigation, computed tomography (CT)-based navigation, and fluoroscopy-based navigation. In imageless navigation system, a new method of registration without the need to register the anterior pelvic plane was introduced. CT-based navigation can be efficiently used for pelvic plane reference, the functional pelvic plane in supine which adjusts anterior pelvic plane sagittal tilt for targeting the cup orientation. Robot-assisted system can be either active or semi-active. The active robotic system performs the preparation for implant positioning as programmed preoperatively. It has been used for only femoral implant cavity preparation. Recently, program for cup positioning was additionally developed. Alternatively, for ease of surgeon acceptance, semi-active robot systems are developed. It was initially applied only for cup positioning. However, with the development of enhanced femoral workflows, this system can now be used to position both cup and stem. Though there have been substantial advancements in computer-assisted THA, its use can still be controversial at present due to the steep learning curve, intraoperative technical issues, high cost and etc. However, in the future, CAOS will certainly enable the surgeon to operate more accurately and lead to improved outcomes in THA as the technology continues to evolve rapidly.

The Global Positioning System: Theory and operation

NASA Astrophysics Data System (ADS)

Tucker, Lester Plunkett

Scope and method of study. The purpose of this study is to document the theory, development, and training needs of the United States Global Positioning System for the United States Air Force. This subject area had very little information and to assess the United States Air Force training needs required an investigation into existing training accomplished on the Global Positioning System. The United States Air Force has only one place to obtain the data at Headquarters Air Education and Training Command. Findings and conclusion. The United States Air Force, at the time of this study, does not have a theory and operations course dealing with the newest technology advancement in world navigation. Although this new technology is being provided on aircraft in the form of new navigation hardware, no official course of study is provided by the United States Air Force to it's pilots and navigators dealing with theory and operation. Based on the latest reports dealing with the Global Positioning System, a course on the Global Positioning System was developed in the Instructional Systems Design format to provide background information and understanding of this new technology. Readers of this study must be aware that the information contained in this study is very dynamic. Technology is advancing so fast in this area that it might make this information obsolete in a short amount of time.

Flight Mechanics/Estimation Theory Symposium. [with application to autonomous navigation and attitude/orbit determination

NASA Technical Reports Server (NTRS)

Fuchs, A. J. (Editor)

1979-01-01

Onboard and real time image processing to enhance geometric correction of the data is discussed with application to autonomous navigation and attitude and orbit determination. Specific topics covered include: (1) LANDSAT landmark data; (2) star sensing and pattern recognition; (3) filtering algorithms for Global Positioning System; and (4) determining orbital elements for geostationary satellites.

Blocking Spatial Navigation Across Environments That Have a Different Shape

PubMed Central

2015-01-01

According to the geometric module hypothesis, organisms encode a global representation of the space in which they navigate, and this representation is not prone to interference from other cues. A number of studies, however, have shown that both human and non-human animals can navigate on the basis of local geometric cues provided by the shape of an environment. According to the model of spatial learning proposed by Miller and Shettleworth (2007, 2008), geometric cues compete for associative strength in the same manner as non-geometric cues do. The experiments reported here were designed to test if humans learn about local geometric cues in a manner consistent with the Miller-Shettleworth model. Experiment 1 replicated previous findings that humans transfer navigational behavior, based on local geometric cues, from a rectangle-shaped environment to a kite-shaped environment, and vice versa. In Experiments 2 and 3, it was observed that learning about non-geometric cues blocked, and were blocked by, learning about local geometric cues. The reciprocal blocking observed is consistent with associative theories of spatial learning; however, it is difficult to explain the observed effects with theories of global-shape encoding in their current form. PMID:26569017

Navigating Through Chaos: Charge Nurses and Patient Safety.

PubMed

Cathro, Heather

2016-04-01

The aim of this study was to explore actions and the processes charge nurses (CNs) implement to keep patients safe and generate an emerging theory to inform CN job descriptions, orientation, and training to promote patient safety in practice. Healthcare workers must provide a safe environment for patients. CNs are the frontline leaders on most hospital units and can function as gatekeepers for safe patient care. This grounded theory study utilized purposive sampling of CNs on medical-surgical units in a 400-bed metropolitan hospital. Data collection consisted of 11 interviews and 6 observations. The emerging theory was navigating through chaos: CNs balancing multiple roles, maintaining a watchful eye, and working with and leading the healthcare team to keep patients safe. CNs have knowledge of patients, staff, and complex healthcare environments, putting them in opportune positions to influence patient safety.

Standing between Two Worlds in Harlem: A Developmental Psychopathology Perspective of Perinatally Acquired Human Immunodeficiency Virus and Adolescence

ERIC Educational Resources Information Center

Kang, Ezer; Mellins, Claude Ann; Ng, Warren Yiu Kee; Robinson, Lisa-Gaye; Abrams, Elaine J.

2008-01-01

Perinatal HIV infection in the US continues to evolve from a fatal pediatric illness to a chronic medical condition of childhood and adolescence. Although navigating this period is influenced by multi-leveled deprivations commonly experienced by low-income minority families, HIV alters the timing and experience of developmental milestones for many…

Flight Mechanics/Estimation Theory Symposium

NASA Technical Reports Server (NTRS)

Fuchs, A. J. (Editor)

1980-01-01

Methods of determining satellite orbit and attitude parameters are considered. The Goddard Trajectory Determination System, the Global Positioning System, and the Tracking and Data Relay Satellites are among the satellite navigation systems discussed. Satellite perturbation theory, orbit/attitude determination using landmark data, and star measurements are also covered.

Development of a Radio Frequency Space Environment Path Emulator for Evaluating Spacecraft Ranging Hardware

NASA Technical Reports Server (NTRS)

Mitchell, Jason W.; Baldwin, Philip J.; Kurichh, Rishi; Naasz, Bo J.; Luquette, Richard J.

2007-01-01

The Formation Flying Testbed (FFTB) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) provides a hardware-in-the-loop test environment for formation navigation and control. The facility is evolving as a modular, hybrid, dynamic simulation facility for end-to-end guidance, navigation and. control (GN&C) design and analysis of formation flying spacecraft. The core capabilities of the FFTB, as a platform for testing critical hardware and software algorithms in-the-loop, have expanded to include S-band Radio Frequency (RF) modems for inter-spacecraft communication and ranging. To enable realistic simulations that require RF ranging sensors for relative navigation, a mechanism is needed to buffer the RF signals exchanged between spacecraft that accurately emulates the dynamic environment through which the RF signals travel, including the effects of medium, moving platforms, and radiated power. The Path Emulator for RF Signals (PERFS), currently under development at NASA GSFC, provides this capability. The function and performance of a prototype device are presented.

Characterization of a Prototype Radio Frequency Space Environment Path Emulator for Evaluating Spacecraft Ranging Hardware

NASA Technical Reports Server (NTRS)

Mitchell, Jason W.; Baldwin, Philip J.; Kurichh, Rishi; Naasz, Bo J.; Luquette, Richard J.

2007-01-01

The Formation Flying Testbed (FFTB) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) provides a hardware-in-the-loop test environment for formation navigation and control. The facility is evolving as a modular, hybrid, dynamic simulation facility for end-to-end guidance, navigation and control (GN&C) design and analysis of formation flying spacecraft. The core capabilities of the FFTB, as a platform for testing critical hardware and software algorithms in-the-loop, have expanded to include S-band Radio Frequency (RF) modems for interspacecraft communication and ranging. To enable realistic simulations that require RF ranging sensors for relative navigation, a mechanism is needed to buffer the RF signals exchanged between spacecraft that accurately emulates the dynamic environment through which the RF signals travel, including the effects of the medium, moving platforms, and radiated power. The Path Emulator for Radio Frequency Signals (PERFS), currently under development at NASA GSFC, provides this capability. The function and performance of a prototype device are presented.

Autonomous Flight Rules - A Concept for Self-Separation in U.S. Domestic Airspace

NASA Technical Reports Server (NTRS)

Wing, David J.; Cotton, William B.

2011-01-01

Autonomous Flight Rules (AFR) are proposed as a new set of operating regulations in which aircraft navigate on tracks of their choice while self-separating from traffic and weather. AFR would exist alongside Instrument and Visual Flight Rules (IFR and VFR) as one of three available flight options for any appropriately trained and qualified operator with the necessary certified equipment. Historically, ground-based separation services evolved by necessity as aircraft began operating in the clouds and were unable to see each other. Today, technologies for global navigation, airborne surveillance, and onboard computing enable the functions of traffic conflict management to be fully integrated with navigation procedures onboard the aircraft. By self-separating, aircraft can operate with more flexibility and fewer restrictions than are required when using ground-based separation. The AFR concept is described in detail and provides practical means by which self-separating aircraft could share the same airspace as IFR and VFR aircraft without disrupting the ongoing processes of Air Traffic Control.

Almanac services for celestial navigation

NASA Astrophysics Data System (ADS)

Nelmes, S.; Whittaker, J.

2015-08-01

Celestial navigation remains a vitally important back up to Global Navigation Satellite Systems (GNSS) and relies on the use of almanac services. HM Nautical Almanac Office (HMNAO) provides a number of these services. The printed book, The Nautical Almanac, produced yearly and now available as an electronic publication, is continuously being improved, making use of the latest ideas and ephemerides to provide the user with their required data. HMNAO also produces NavPac, a software package that assists the user in calculating their position as well as providing additional navigational and astronomical tools. A new version of NavPac will be released in 2015 that will improve the user experience. The development of applications for mobile devices is also being considered. HMNAO continues to combine the latest improvements and theories of astrometry with the creation of books and software that best meet the needs of celestial navigation users.

Distant touch hydrodynamic imaging with an artificial lateral line.

PubMed

Yang, Yingchen; Chen, Jack; Engel, Jonathan; Pandya, Saunvit; Chen, Nannan; Tucker, Craig; Coombs, Sheryl; Jones, Douglas L; Liu, Chang

2006-12-12

Nearly all underwater vehicles and surface ships today use sonar and vision for imaging and navigation. However, sonar and vision systems face various limitations, e.g., sonar blind zones, dark or murky environments, etc. Evolved over millions of years, fish use the lateral line, a distributed linear array of flow sensing organs, for underwater hydrodynamic imaging and information extraction. We demonstrate here a proof-of-concept artificial lateral line system. It enables a distant touch hydrodynamic imaging capability to critically augment sonar and vision systems. We show that the artificial lateral line can successfully perform dipole source localization and hydrodynamic wake detection. The development of the artificial lateral line is aimed at fundamentally enhancing human ability to detect, navigate, and survive in the underwater environment.

Capturing the Sun: A Roadmap for Navigating Data-Access Challenges and Auto-Populating Solar Home Sales Listings

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

Stukel, Laura; Hoen, Ben; Adomatis, Sandra

Capturing the Sun: A Roadmap for Navigating Data-Access Challenges and Auto-Populating Solar Home Sales Listings supports a vision of solar photovoltaic (PV) advocates and real estate advocates evolving together to make information about solar homes more accessible to home buyers and sellers and to simplify the process when these homes are resold. The Roadmap is based on a concept in the real estate industry known as automatic population of fields. Auto-population (also called auto-pop in the industry) is the technology that allows data aggregated by an outside industry to be matched automatically with home sale listings in a multiple listingmore » service (MLS).« less

Impaired Spatial Navigation in Pediatric Anxiety

ERIC Educational Resources Information Center

Mueller, Sven C.; Temple, Veronica; Cornwell, Brian; Grillon, Christian; Pine, Daniel S.; Ernst, Monique

2009-01-01

Background: Previous theories implicate hippocampal dysfunction in anxiety disorders. Most of the data supporting these theories stem from animal research, particularly lesion studies. The generalization of findings from rodent models to human function is hampered by fundamental inter-species differences. The present work uses a task of spatial…

Moving in Dim Light: Behavioral and Visual Adaptations in Nocturnal Ants.

PubMed

Narendra, Ajay; Kamhi, J Frances; Ogawa, Yuri

2017-11-01

Visual navigation is a benchmark information processing task that can be used to identify the consequence of being active in dim-light environments. Visual navigational information that animals use during the day includes celestial cues such as the sun or the pattern of polarized skylight and terrestrial cues such as the entire panorama, canopy pattern, or significant salient features in the landscape. At night, some of these navigational cues are either unavailable or are significantly dimmer or less conspicuous than during the day. Even under these circumstances, animals navigate between locations of importance. Ants are a tractable system for studying navigation during day and night because the fine scale movement of individual animals can be recorded in high spatial and temporal detail. Ant species range from being strictly diurnal, crepuscular, and nocturnal. In addition, a number of species have the ability to change from a day- to a night-active lifestyle owing to environmental demands. Ants also offer an opportunity to identify the evolution of sensory structures for discrete temporal niches not only between species but also within a single species. Their unique caste system with an exclusive pedestrian mode of locomotion in workers and an exclusive life on the wing in males allows us to disentangle sensory adaptations that cater for different lifestyles. In this article, we review the visual navigational abilities of nocturnal ants and identify the optical and physiological adaptations they have evolved for being efficient visual navigators in dim-light. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Disposal strategy for the geosynchronous orbits of the Beidou Navigation Satellite System

NASA Astrophysics Data System (ADS)

Tang, Jingshi; Liu, Lin

Beidou Navigation Satellite System (BDS) is China's navigation satelite system. It is now operational for navigation service in China and Asia-Pacific region and is due to be fully operational as a global navigation system by 2020. Unlike other navigation satellite systems, BDS consists of both 12-hour medium Earth orbit and 24-hour geosynchronous orbit. To sustain a safe environment for the navigation satellites, the end-of-life satellites must be disposed appropriately so they do not pose potential dangers to the operational satellites. There are currently two strategies for the disposal orbit. One is to put the disposed satellite in a graveyard orbit that has a safe distance from the operational satellites. It is often applied in geosynchronous orbits and such graveyard orbit can always maintain a safe distance even for a few centuries. This strategy is also currently adopted by GPS, yet recent researches show a re-entry orbit can sometimes be a better alternative. The interaction of Earth oblateness and lunisolar gravitation can lead to a rapid increase in the orbit eccentricity such that by proper design the disposed GPS satellite can be cleared out by re-entry into the atmosphere. In this work we focus on the disposal strategy for BDS geosynchronous orbit, which consists of the equatorial stationary orbit (GEO) and the inclined orbit (IGSO). We show that these two orbits are essentially in two different dynamical environments and evolve quite distinctly over a long period of time. Taking advantage of the dynamic nature, we apply the graveyard orbit and the re-entry orbit to GEO and IGSO respectively and propose appropriate disposal strategies accordingly.

The Evolution of Computer-Assisted Total Hip Arthroplasty and Relevant Applications

PubMed Central

Kim, In-Sung; Bhardwaj, Atul M.; Badami, Ramachandra N.

2017-01-01

In total hip arthroplasty (THA), the accurate positioning of implants is the key to achieve a good clinical outcome. Computer-assisted orthopaedic surgery (CAOS) has been developed for more accurate positioning of implants during the THA. There are passive, semi-active, and active systems in CAOS for THA. Navigation is a passive system that only provides information and guidance to the surgeon. There are 3 types of navigation: imageless navigation, computed tomography (CT)-based navigation, and fluoroscopy-based navigation. In imageless navigation system, a new method of registration without the need to register the anterior pelvic plane was introduced. CT-based navigation can be efficiently used for pelvic plane reference, the functional pelvic plane in supine which adjusts anterior pelvic plane sagittal tilt for targeting the cup orientation. Robot-assisted system can be either active or semi-active. The active robotic system performs the preparation for implant positioning as programmed preoperatively. It has been used for only femoral implant cavity preparation. Recently, program for cup positioning was additionally developed. Alternatively, for ease of surgeon acceptance, semi-active robot systems are developed. It was initially applied only for cup positioning. However, with the development of enhanced femoral workflows, this system can now be used to position both cup and stem. Though there have been substantial advancements in computer-assisted THA, its use can still be controversial at present due to the steep learning curve, intraoperative technical issues, high cost and etc. However, in the future, CAOS will certainly enable the surgeon to operate more accurately and lead to improved outcomes in THA as the technology continues to evolve rapidly. PMID:28316957

Neuropsychological Components of Imagery Processing, Final Technical Report.

ERIC Educational Resources Information Center

Kosslyn, Stephen M.

High-level visual processes make use of stored information, and are invoked during object identification, navigation, tracking, and visual mental imagery. The work presented in this document has resulted in a theory of the component "processing subsystems" used in high-level vision. This theory was developed by considering…

Ecosystemic Complexity Theory of Conflict: Understanding the Fog of Conflict

ERIC Educational Resources Information Center

Brack, Greg; Lassiter, Pamela S.; Hill, Michele B.; Moore, Sarah A.

2011-01-01

Counselors often engage in conflict mediation in professional practice. A model for understanding the complex and subtle nature of conflict resolution is presented. The ecosystemic complexity theory of conflict is offered to assist practitioners in navigating the fog of conflict. Theoretical assumptions are discussed with implications for clinical…

Navigating the field of temporally framed care in the Danish home care sector.

PubMed

Tufte, Pernille; Dahl, Hanne Marlene

2016-01-01

The organisational and temporal framing of elderly care in Europe has changed in the wake of new public management reforms and standardised care services, the strict measurement of time and work schedules have become central aspects of care work. The article investigates the crafting of care in this framing: how care workers approach the services specified in their rotas and navigate between needs, demands and opportunities in the daily performance of duties. Applying feminist theory on time and anthropological theory on social navigation, it examines the practice of home care work in two Danish municipalities. Data are derived predominantly from participant observation. The article identifies two overarching temporal dilemmas in different home care situations: one where process time prevails over clock time and another where the care workers balance the two. Focusing on how care workers respond to these dilemmas in practice, the article identifies various navigation tactics, including leaving time outside, individualised routinisation, working on different paths simultaneously and postponing tasks. By assessing care workers' performance in the temporal framing of work and focusing on care workers' mediation between different time logics, this study provides an in-depth perspective on the broader feminist literature on the dilemmas of care. © 2015 Foundation for the Sociology of Health & Illness.

Accuracy of the hypothetical sky-polarimetric Viking navigation versus sky conditions: revealing solar elevations and cloudinesses favourable for this navigation method

NASA Astrophysics Data System (ADS)

Száz, Dénes; Farkas, Alexandra; Barta, András; Kretzer, Balázs; Blahó, Miklós; Egri, Ádám; Szabó, Gyula; Horváth, Gábor

2017-09-01

According to Thorkild Ramskou's theory proposed in 1967, under overcast and foggy skies, Viking seafarers might have used skylight polarization analysed with special crystals called sunstones to determine the position of the invisible Sun. After finding the occluded Sun with sunstones, its elevation angle had to be measured and its shadow had to be projected onto the horizontal surface of a sun compass. According to Ramskou's theory, these sunstones might have been birefringent calcite or dichroic cordierite or tourmaline crystals working as polarizers. It has frequently been claimed that this method might have been suitable for navigation even in cloudy weather. This hypothesis has been accepted and frequently cited for decades without any experimental support. In this work, we determined the accuracy of this hypothetical sky-polarimetric Viking navigation for 1080 different sky situations characterized by solar elevation θ and cloudiness ρ, the sky polarization patterns of which were measured by full-sky imaging polarimetry. We used the earlier measured uncertainty functions of the navigation steps 1, 2 and 3 for calcite, cordierite and tourmaline sunstone crystals, respectively, and the newly measured uncertainty function of step 4 presented here. As a result, we revealed the meteorological conditions under which Vikings could have used this hypothetical navigation method. We determined the solar elevations at which the navigation uncertainties are minimal at summer solstice and spring equinox for all three sunstone types. On average, calcite sunstone ensures a more accurate sky-polarimetric navigation than tourmaline and cordierite. However, in some special cases (generally at 35° ≤ θ ≤ 40°, 1 okta ≤ ρ ≤ 6 oktas for summer solstice, and at 20° ≤ θ ≤ 25°, 0 okta ≤ ρ ≤ 4 oktas for spring equinox), the use of tourmaline and cordierite results in smaller navigation uncertainties than that of calcite. Generally, under clear or less cloudy skies, the sky-polarimetric navigation is more accurate, but at low solar elevations its accuracy remains relatively large even at high cloudiness. For a given ρ, the absolute value of averaged peak North uncertainties dramatically decreases with increasing θ until the sign (±) change of these uncertainties. For a given θ, this absolute value can either decrease or increase with increasing ρ. The most advantageous sky situations for this navigation method are at summer solstice when the solar elevation and cloudiness are 35° ≤ θ ≤ 40° and 2 oktas ≤ ρ ≤ 3 oktas.

Image processing and applications based on visualizing navigation service

NASA Astrophysics Data System (ADS)

Hwang, Chyi-Wen

2015-07-01

When facing the "overabundant" of semantic web information, in this paper, the researcher proposes the hierarchical classification and visualizing RIA (Rich Internet Application) navigation system: Concept Map (CM) + Semantic Structure (SS) + the Knowledge on Demand (KOD) service. The aim of the Multimedia processing and empirical applications testing, was to investigating the utility and usability of this visualizing navigation strategy in web communication design, into whether it enables the user to retrieve and construct their personal knowledge or not. Furthermore, based on the segment markets theory in the Marketing model, to propose a User Interface (UI) classification strategy and formulate a set of hypermedia design principles for further UI strategy and e-learning resources in semantic web communication. These research findings: (1) Irrespective of whether the simple declarative knowledge or the complex declarative knowledge model is used, the "CM + SS + KOD navigation system" has a better cognition effect than the "Non CM + SS + KOD navigation system". However, for the" No web design experience user", the navigation system does not have an obvious cognition effect. (2) The essential of classification in semantic web communication design: Different groups of user have a diversity of preference needs and different cognitive styles in the CM + SS + KOD navigation system.

The evolution of genomic imprinting: theories, predictions and empirical tests

PubMed Central

Patten, M M; Ross, L; Curley, J P; Queller, D C; Bonduriansky, R; Wolf, J B

2014-01-01

The epigenetic phenomenon of genomic imprinting has motivated the development of numerous theories for its evolutionary origins and genomic distribution. In this review, we examine the three theories that have best withstood theoretical and empirical scrutiny. These are: Haig and colleagues' kinship theory; Day and Bonduriansky's sexual antagonism theory; and Wolf and Hager's maternal–offspring coadaptation theory. These theories have fundamentally different perspectives on the adaptive significance of imprinting. The kinship theory views imprinting as a mechanism to change gene dosage, with imprinting evolving because of the differential effect that gene dosage has on the fitness of matrilineal and patrilineal relatives. The sexual antagonism and maternal–offspring coadaptation theories view genomic imprinting as a mechanism to modify the resemblance of an individual to its two parents, with imprinting evolving to increase the probability of expressing the fitter of the two alleles at a locus. In an effort to stimulate further empirical work on the topic, we carefully detail the logic and assumptions of all three theories, clarify the specific predictions of each and suggest tests to discriminate between these alternative theories for why particular genes are imprinted. PMID:24755983

Teaching and learning apheresis medicine: The Bermuda Triangle in Education.

PubMed

Crookston, Kendall P; Richter, Deana M

2010-01-01

Apheresis Medicine has evolved markedly due to an explosion of knowledge and technology, whereas the time available for training has shrunk as curricula have become increasingly overloaded. Apheresis teaching has inherited a strong clinical context where real patient problems are used in a hands-on environment. To optimize instruction, those involved in the education of apheresis professionals need to have (1) knowledge of how clinical laboratory medicine education has developed as a field, (2) an understanding of what is known from theory and research about how people learn, and (3) the skills to design teaching/learning activities in ways consistent with literature-based principles of adult education. These developments in education provide a context for curriculum projects currently underway by the American Society for Apheresis. Teachers must determine which competencies are central to the essence of a trained professional. Specific, robust, learning objectives targeted toward the development of higher levels of thinking, professional attitudes, and requisite skills are formulated to guide the learner toward mastering those competencies. Curriculum is developed for each objective, consisting of content and the best teaching/learning methods to help learners attain the objective. Appropriate assessment strategies are identified to determine whether the objective is being achieved. The integration of objectives, curriculum, and assessment creates The Bermuda Triangle of Education (Richter, The Circle of Learning and Bermuda Triangle in Education, University of New Mexico School of Medicine, 2004). When educators do not effectively navigate The Bermuda Triangle of Education, learning may disappear into the murky depths of confusion and apathy. When successfully navigated, the result will be a significant learning experience that leads to transformation through education. 2010 Wiley-Liss, Inc.

Am I Wearing the Right Hat? Navigating Professional Relationships between Parent-Teachers and Their Colleagues

ERIC Educational Resources Information Center

Lipsky, Eliana; Friedman, Ilana Dvorin; Harkema, Rebecca

2017-01-01

Utilizing organizational role theory and cognitive role theory as a theoretical framework, this phenomenological study examined the experience of parent-teachers and colleague-teachers in small educational settings and their perceptions of these dynamic relationships and potential areas of conflict. Findings highlighted perceived strengths, yet…

Navigating Theory and Practice through Evaluation Fieldwork: Experiences of Novice Evaluation Practitioners

ERIC Educational Resources Information Center

Chouinard, Jill Anne; Boyce, Ayesha S.; Hicks, Juanita; Jones, Jennie; Long, Justin; Pitts, Robyn; Stockdale, Myrah

2017-01-01

To explore the relationship between theory and practice in evaluation, we focus on the perspectives and experiences of student evaluators, as they move from the classroom to an engagement with the social, political, and cultural dynamics of evaluation in the field. Through reflective journals, postcourse interviews, and facilitated group…

Navigating translational ecology: Creating opportunities for scientist participation

USGS Publications Warehouse

Hallett, Lauren M.; Morelli, Toni; Gerber, Leah R.; Moritz, Max A.; Schwartz, Mark W.; Stephenson, Nathan L.; Tank, Jennifer L.; Williamson, Matthew A.; Woodhouse, Connie A.

2017-01-01

Interest in translational ecology (TE) – a research approach that yields useful scientific outcomes through ongoing collaboration between scientists and stakeholders – is growing among both of these groups. Translational ecology brings together participants from different cultures and with different professional incentives. We address ways to cultivate a culture of TE, such as investing time in understanding one another's decision context and incentives, and outline common entry points to translational research, such as working through boundary organizations, building place-based research programs, and being open to opportunities as they arise. We also highlight common institutional constraints on scientists and practitioners, and ways in which collaborative research can overcome these limitations, emphasizing considerations for navigating TE within current institutional frameworks, but also pointing out ways in which institutions are evolving to facilitate translational research approaches.

Fifth Annual Flight Mechanics/Estimation Theory Symposium

NASA Technical Reports Server (NTRS)

Teles, J. (Editor)

1980-01-01

Various aspects of astrodynamics are considered including orbit calculations and trajectory determination. Other topics dealing with remote sensing systems, satellite navigation, and attitude control are included.

The evolutionary origin and diversification of feathers.

PubMed

Prum, Richard O; Brush, Alan H

2002-09-01

Progress on the evolutionary origin and diversification of feathers has been hampered by conceptual problems and by the lack of plesiomorphic feather fossils. Recently, both of these limitations have been overcome by the proposal of the developmental theory of the origin of feathers, and the discovery of primitive feather fossils on nonavian theropod dinosaurs. The conceptual problems of previous theories of the origin of feathers are reviewed, and the alternative developmental theory is presented and discussed. The developmental theory proposes that feathers evolved through a series of evolutionary novelties in developmental mechanisms of the follicle and feather germ. The discovery of primitive and derived fossil feathers on a diversity of coelurosaurian theropod dinosaurs documents that feathers evolved and diversified in nonavian theropods before the origin of birds and before the origin of flight. The morphologies of these primitive feathers are congruent with the predictions of the developmental theory. Alternatives to the theropod origin of feathers are critique and rejected. Hypotheses for the initial function of feathers are reviewed. The aerodynamic theory of feather origins is falsified, but many other functions remain developmentally and phylogenetically plausible. Whatever their function, feathers evolved by selection for a follicle that would grow an emergent tubular appendage. Feathers are inherently tubular structures. The homology of feathers and scales is weakly supported. Feathers are composed of a suite of evolutionary novelties that evolved by the duplication, hierarchical organization, interaction, dissociation, and differentiation of morphological modules. The unique capacity for modular subdivision of the tubular feather follicle and germ has fostered the evolution of numerous innovations that characterize feathers. The evolution of feather keratin and the molecular basis of feather development are also discussed.

Using Program Theory-Driven Evaluation Science to Crack the Da Vinci Code

ERIC Educational Resources Information Center

Donaldson, Stewart I.

2005-01-01

Program theory-driven evaluation science uses substantive knowledge, as opposed to method proclivities, to guide program evaluations. It aspires to update, clarify, simplify, and make more accessible the evolving theory of evaluation practice commonly referred to as theory-driven or theory-based evaluation. The evaluator in this chapter provides a…

Genomic basis for the convergent evolution of electric organs

PubMed Central

Gallant, Jason R.; Traeger, Lindsay L.; Volkening, Jeremy D.; Moffett, Howell; Chen, Po-Hao; Novina, Carl D.; Phillips, George N.; Anand, Rene; Wells, Gregg B.; Pinch, Matthew; Güth, Robert; Unguez, Graciela A.; Albert, James S.; Zakon, Harold H.; Samanta, Manoj P.; Sussman, Michael R.

2017-01-01

Little is known about the genetic basis of convergent traits that originate repeatedly over broad taxonomic scales. The myogenic electric organ has evolved six times in fishes to produce electric fields used in communication, navigation, predation, or defense. We have examined the genomic basis of the convergent anatomical and physiological origins of these organs by assembling the genome of the electric eel (Electrophorus electricus) and sequencing electric organ and skeletal muscle transcriptomes from three lineages that have independently evolved electric organs. Our results indicate that, despite millions of years of evolution and large differences in the morphology of electric organ cells, independent lineages have leveraged similar transcription factors and developmental and cellular pathways in the evolution of electric organs. PMID:24970089

The Evolution of an Innovative Community-Engaged Health Navigator Program to Address Social Determinants of Health.

PubMed

Page-Reeves, Janet; Moffett, Maurice L; Steimel, Leah; Smith, Daryl T

Health navigators and other types of community health workers (CHWs) have become recognized as essential components of quality care, and key for addressing health disparities owing to the complex health care services landscape presents almost insurmountable challenges for vulnerable individuals. Bernalillo County, New Mexico, has high rates of uninsurance, poverty, and food insecurity. The design of the Pathways to a Healthy Bernalillo County Program (BP) has evolved innovations that are unique in terms of program stability and security, expansive reach, and community capacity across six domains: sustainable public mechanism for program funding, involvement of community organizations in designing the program, expanded focus to address the broader social determinants of health with targeted outreach, an integrated, community-based implementation structure, an outcomes-based payment structure, and using an adaptive program design that actively incorporates navigators in the process. In 2008, the Pathways to a Healthy Bernalillo County Program (BP), located in the Albuquerque metropolitan area in central New Mexico, was established to provide navigation and support for the most vulnerable county residents. BP is funded through a 1% carve out of county mill levy funds. The pathways model is an outcome-based approach for health and social services coordination that uses culturally competent CHW as "navigators" trained to connect at-risk individuals to needed health and social services. One of the important innovations of the pathways approach is a shift in focus from merely providing discrete services to confirming healthy outcomes for the individual patient.

Personality Theories for the 21st Century

ERIC Educational Resources Information Center

McCrae, Robert R.

2011-01-01

Classic personality theories, although intriguing, are outdated. The five-factor model of personality traits reinvigorated personality research, and the resulting findings spurred a new generation of personality theories. These theories assign a central place to traits and acknowledge the crucial role of evolved biology in shaping human…

Surface capillary currents: Rediscovery of fluid-structure interaction by forced evolving boundary theory

NASA Astrophysics Data System (ADS)

Wang, Chunbai; Mitra, Ambar K.

2016-01-01

Any boundary surface evolving in viscous fluid is driven with surface capillary currents. By step function defined for the fluid-structure interface, surface currents are found near a flat wall in a logarithmic form. The general flat-plate boundary layer is demonstrated through the interface kinematics. The dynamics analysis elucidates the relationship of the surface currents with the adhering region as well as the no-slip boundary condition. The wall skin friction coefficient, displacement thickness, and the logarithmic velocity-defect law of the smooth flat-plate boundary-layer flow are derived with the advent of the forced evolving boundary method. This fundamental theory has wide applications in applied science and engineering.

Navigating cancer using online communities: a grounded theory of survivor and family experiences.

PubMed

Harkin, Lydia Jo; Beaver, Kinta; Dey, Paola; Choong, Kartina

2017-12-01

People affected by cancer often have unmet emotional and social support needs. Online cancer communities are a convenient channel for connecting cancer survivors, allowing them to support one another. However, it is unclear whether online community use makes a meaningful contribution to cancer survivorship, as little previous research has examined the experience of using contemporary cancer communities. We aimed to explore the experiences of visitors to online cancer communities. Twenty-three in-depth interviews were conducted with online cancer community visitors, including cancer survivors (n = 18), family members (n = 2), and individuals who were both a survivor and family member (n = 3). Interviews were analysed using a grounded theory approach. A theory developed explaining how individuals 'navigated' the experience of cancer using online cancer communities. Online advice and information led participants on a 'journey to become informed'. Online friendships normalised survivorship and cast participants on a 'journey to recreate identity'. Participants navigated a 'journey through different worlds' as they discovered relevant and hidden communities. This theory highlights virtual paths people affected by cancer can take to self-manage their experience of the disease. Online community experiences can be improved by promoting online evaluation skills and signposting visitors to bereavement support. Cancer survivors can benefit through both lurking and posting in online communities. However, individuals risk becoming distressed when they befriend individuals who may soon die. Additionally, people affected by rarer cancers can struggle to find shared experiences online and may need to look elsewhere for support.

Recent Developments in Hardware-in-the-Loop Formation Navigation and Control

NASA Technical Reports Server (NTRS)

Mitchell, Jason W.; Luquette, Richard J.

2005-01-01

The Formation Flying Test-Bed (FFTB) at NASA Goddard Space Flight Center (GSFC) provides a hardware-in-the-loop test environment for formation navigation and control. The facility is evolving as a modular, hybrid, dynamic simulation facility for end-tc-end guidance, navigation, and control (GN&C) design and analysis of formation flying spacecraft. The core capabilities of the FFTB, as a platform for testing critical hardware and software algorithms in-the-loop, are reviewed with a focus on many recent improvements. Two significant upgrades to the FFTB are a message-oriented middleware (MOM) architecture, and a software crosslink for inter-spacecraft ranging. The MOM architecture provides a common messaging bus for software agents, easing integration, arid supporting the GSFC Mission Services Evolution Center (GMSEC) architecture via software bridge. Additionally, the FFTB s hardware capabilities are expanding. Recently, two Low-Power Transceivers (LPTs) with ranging capability have been introduced into the FFTB. The LPT crosslinks will be connected to a modified Crosslink Channel Simulator (CCS), which applies realistic space-environment effects to the Radio Frequency (RF) signals produced by the LPTs.

The evolution of breast cancer navigation and survivorship care.

PubMed

Shockney, Lillie D

2015-01-01

Over the last several decades, breast screening, diagnosis, and treatment have evolved. With that evolutionary process, so have the complexities of oncology care, especially from the perspective of more fragmented care occurring. The majority of breast care is outpatient based. The need for patient navigation has heightened as this fragmentation and financial issues set before the oncologist and the patient continue to occur and in many situations increase. Without effective navigation, breast patients can fall through the cracks and not get diagnosed as early as possible, or not receive all appropriate treatment they need. We are also seeing a steady increase in the actual number of breast cancer patients being diagnosed and surviving long term. Unfortunately simultaneous to this happen there is also a growing shortage of oncology specialists in the USA. This results in a need to transition survivors back to their community physicians after the completion of their acute treatment, and to do so in an organized, anticipated manner that prepares the survivor and her PCP and gynecologist, the tools they all need for effective cancer survivorship management. © 2014 Wiley Periodicals, Inc.

Puzzling the Picture Using Grounded Theory

ERIC Educational Resources Information Center

Bennett, Elisabeth E.

2016-01-01

Since the first publication by Glaser and Strauss in 1967, Grounded Theory has become a highly influential research approach in the social sciences. The approach provides techniques and coding strategies for building theory inductively from the "ground up" as concepts within the data earn relevance into an evolving substantive theory.…

A theory of viscoplasticity accounting for internal damage

NASA Technical Reports Server (NTRS)

Freed, A. D.; Robinson, D. N.

1988-01-01

A constitutive theory for use in structural and durability analyses of high temperature isotropic alloys is presented. Constitutive equations based upon a potential function are determined from conditions of stability and physical considerations. The theory is self-consistent; terms are not added in an ad hoc manner. It extends a proven viscoplastic model by introducing the Kachanov-Rabotnov concept of net stress. Material degradation and inelastic deformation are unified; they evolve simultaneously and interactively. Both isotropic hardening and material degradation evolve with dissipated work which is the sum of inelastic work and internal work. Internal work is a continuum measure of the stored free energy resulting from inelastic deformation.

Fission Chain Restart Theory

DOE PAGES

Kim, K. S.; Nakae, L. F.; Prasad, M. K.; ...

2017-07-31

We present that fast nanosecond timescale neutron and gamma-ray counting can be performed with a (liquid) scintillator array. Fission chains in metal evolve over a timescale of tens of nanoseconds. If the metal is surrounded by moderator, neutrons leaking from the metal can thermalize and diffuse in the moderator. With finite probability, the diffusing neutrons can return to the metal and restart the fast fission chain. The timescale for this restart process is microseconds. A theory describing time evolving fission chains for metal surrounded by moderator, including this restart process, is presented. Finally, this theory is sufficiently simple for itmore » to be implemented for real-time analysis.« less

The Collective Knowledge of Social Tags: Direct and Indirect Influences on Navigation, Learning, and Information Processing

ERIC Educational Resources Information Center

Cress, Ulrike; Held, Christoph; Kimmerle, Joachim

2013-01-01

Tag clouds generated in social tagging systems can capture the collective knowledge of communities. Using as a basis spreading activation theories, information foraging theory, and the co-evolution model of cognitive and social systems, we present here a model for an "extended information scent," which proposes that both collective and individual…

How Female Professionals Successfully Process and Negotiate Involuntary Job Loss at Faith-Based Colleges and Universities: A Grounded Theory Study

ERIC Educational Resources Information Center

Cunningham, Debra Jayne

2015-01-01

Using a constructivist grounded theory approach (Charmaz, 2006), this qualitative study examined how eight female senior-level professionals employed at faith-based colleges and universities processed and navigated the experience of involuntary job loss and successfully transitioned to another position. The theoretical framework of psychological…

School Counselors' Strategies for Social Justice Change: A Grounded Theory of What Works in the Real World

ERIC Educational Resources Information Center

Singh, Anneliese A.; Urbano, Alessandra; Haston, Meg; McMahon, Eleanor

2010-01-01

A qualitative study used a grounded theory methodology to explore the strategies that 16 school counselors who self-identified as social justice agents used to advocate for systemic change within their school communities. Findings included seven overarching themes: (a) using political savvy to navigate power structures, (b) consciousness raising,…

Navigating in the landscape of care: a critical reflection on theory and practise of care and ethics.

PubMed

Skærbæk, Eva

2011-03-01

The theory and practise of care is defined and enacted differently in different national as well as cultural contexts, illuminating how differently constructed the personal and societal structures in Europe are. A common trait is however that care work paid or non-paid, private or public is identified with women. To navigate in the landscape of care and ethics requires taking into account the constitutive relation between one's identity, embodiment and position. The author suggests conceiving care as an existential condition of life demanded from all human beings. This will free care from the identification with women and pave a way towards a more gender equal and just society with less gender segregation in the labour market and at the arena of education.

Accuracy of the hypothetical sky-polarimetric Viking navigation versus sky conditions: revealing solar elevations and cloudinesses favourable for this navigation method.

PubMed

Száz, Dénes; Farkas, Alexandra; Barta, András; Kretzer, Balázs; Blahó, Miklós; Egri, Ádám; Szabó, Gyula; Horváth, Gábor

2017-09-01

According to Thorkild Ramskou's theory proposed in 1967, under overcast and foggy skies, Viking seafarers might have used skylight polarization analysed with special crystals called sunstones to determine the position of the invisible Sun. After finding the occluded Sun with sunstones, its elevation angle had to be measured and its shadow had to be projected onto the horizontal surface of a sun compass. According to Ramskou's theory, these sunstones might have been birefringent calcite or dichroic cordierite or tourmaline crystals working as polarizers. It has frequently been claimed that this method might have been suitable for navigation even in cloudy weather. This hypothesis has been accepted and frequently cited for decades without any experimental support. In this work, we determined the accuracy of this hypothetical sky-polarimetric Viking navigation for 1080 different sky situations characterized by solar elevation θ and cloudiness ρ , the sky polarization patterns of which were measured by full-sky imaging polarimetry. We used the earlier measured uncertainty functions of the navigation steps 1, 2 and 3 for calcite, cordierite and tourmaline sunstone crystals, respectively, and the newly measured uncertainty function of step 4 presented here. As a result, we revealed the meteorological conditions under which Vikings could have used this hypothetical navigation method. We determined the solar elevations at which the navigation uncertainties are minimal at summer solstice and spring equinox for all three sunstone types. On average, calcite sunstone ensures a more accurate sky-polarimetric navigation than tourmaline and cordierite. However, in some special cases (generally at 35° ≤  θ  ≤ 40°, 1 okta ≤  ρ  ≤ 6 oktas for summer solstice, and at 20° ≤  θ  ≤ 25°, 0 okta ≤  ρ  ≤ 4 oktas for spring equinox), the use of tourmaline and cordierite results in smaller navigation uncertainties than that of calcite. Generally, under clear or less cloudy skies, the sky-polarimetric navigation is more accurate, but at low solar elevations its accuracy remains relatively large even at high cloudiness. For a given ρ , the absolute value of averaged peak North uncertainties dramatically decreases with increasing θ until the sign (±) change of these uncertainties. For a given θ , this absolute value can either decrease or increase with increasing ρ . The most advantageous sky situations for this navigation method are at summer solstice when the solar elevation and cloudiness are 35° ≤  θ  ≤ 40° and 2 oktas ≤  ρ  ≤ 3 oktas.

Slime mold uses an externalized spatial “memory” to navigate in complex environments

PubMed Central

Reid, Chris R.; Latty, Tanya; Dussutour, Audrey; Beekman, Madeleine

2012-01-01

Spatial memory enhances an organism’s navigational ability. Memory typically resides within the brain, but what if an organism has no brain? We show that the brainless slime mold Physarum polycephalum constructs a form of spatial memory by avoiding areas it has previously explored. This mechanism allows the slime mold to solve the U-shaped trap problem—a classic test of autonomous navigational ability commonly used in robotics—requiring the slime mold to reach a chemoattractive goal behind a U-shaped barrier. Drawn into the trap, the organism must rely on other methods than gradient-following to escape and reach the goal. Our data show that spatial memory enhances the organism’s ability to navigate in complex environments. We provide a unique demonstration of a spatial memory system in a nonneuronal organism, supporting the theory that an externalized spatial memory may be the functional precursor to the internal memory of higher organisms. PMID:23045640

Slime mold uses an externalized spatial "memory" to navigate in complex environments.

PubMed

Reid, Chris R; Latty, Tanya; Dussutour, Audrey; Beekman, Madeleine

2012-10-23

Spatial memory enhances an organism's navigational ability. Memory typically resides within the brain, but what if an organism has no brain? We show that the brainless slime mold Physarum polycephalum constructs a form of spatial memory by avoiding areas it has previously explored. This mechanism allows the slime mold to solve the U-shaped trap problem--a classic test of autonomous navigational ability commonly used in robotics--requiring the slime mold to reach a chemoattractive goal behind a U-shaped barrier. Drawn into the trap, the organism must rely on other methods than gradient-following to escape and reach the goal. Our data show that spatial memory enhances the organism's ability to navigate in complex environments. We provide a unique demonstration of a spatial memory system in a nonneuronal organism, supporting the theory that an externalized spatial memory may be the functional precursor to the internal memory of higher organisms.

Convergence: Human Intelligence The Next 100 Years

ERIC Educational Resources Information Center

Fluellen, Jerry E., Jr.

2005-01-01

How might human intelligence evolve over the next 100 years? This issue paper explores that idea. First, the paper summarizes five emerging perspectives about human intelligence: Howard Gardner's multiple intelligences theory, Robert Sternberg's triarchic theory of intelligence, Ellen Langer's mindfulness theory, David Perkins' learnable…

Evolving institutional and policy frameworks to support adaptation strategies

Treesearch

Dave Cleaves

2014-01-01

Given the consequences and opportunities of the Anthropocene, what is our underlying theory or vision of successful adaptation? This essay discusses the building blocks of this theory, and how will we translate this theory into guiding principles for management and policy.

Organizational Learning Theory in Schools

ERIC Educational Resources Information Center

Fauske, Janice R.; Raybould, Rebecca

2005-01-01

Purpose: The paper's purposes are to establish organizational learning theory as evolving from the theoretical and empirical study of organizations and to build grounded theory explaining organizational learning in schools. Design/methodology/approach: Implementation of instructional technology as a process of organizational learning was explored…

The Evolvement of Automobile Steering System Based on TRIZ

NASA Astrophysics Data System (ADS)

Zhao, Xinjun; Zhang, Shuang

Products and techniques pass through a process of birth, growth, maturity, death and quit the stage like biological evolution process. The developments of products and techniques conform to some evolvement rules. If people know and hold these rules, they can design new kind of products and forecast the develop trends of the products. Thereby, enterprises can grasp the future technique directions of products, and make product and technique innovation. Below, based on TRIZ theory, the mechanism evolvement, the function evolvement and the appearance evolvement of automobile steering system had been analyzed and put forward some new ideas about future automobile steering system.

Vision and visual navigation in nocturnal insects.

PubMed

Warrant, Eric; Dacke, Marie

2011-01-01

With their highly sensitive visual systems, nocturnal insects have evolved a remarkable capacity to discriminate colors, orient themselves using faint celestial cues, fly unimpeded through a complicated habitat, and navigate to and from a nest using learned visual landmarks. Even though the compound eyes of nocturnal insects are significantly more sensitive to light than those of their closely related diurnal relatives, their photoreceptors absorb photons at very low rates in dim light, even during demanding nocturnal visual tasks. To explain this apparent paradox, it is hypothesized that the necessary bridge between retinal signaling and visual behavior is a neural strategy of spatial and temporal summation at a higher level in the visual system. Exactly where in the visual system this summation takes place, and the nature of the neural circuitry that is involved, is currently unknown but provides a promising avenue for future research.

27th Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting

NASA Technical Reports Server (NTRS)

Sydnor, Richard L. (Editor)

1996-01-01

This document is a compilation of technical papers presented at the 27th Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting, held November 29 - December 1, 1995 at San Diego, CA. Papers are in the following categories: Recent developments in rubidium, cesium, and hydrogen-based frequency standards; and in cryogenic and trapped-ion technology; International and transnational applications of PTTI technology with emphasis on satellite laser tracking, GLONASS timing, intercomparison of national time scales and international telecommunications; Applications of PTTI technology to the telecommunications, power distribution, platform positioning, and geophysical survey industries; Applications of PTTI technology to evolving military communications and navigation systems; and Dissemination of precise time and frequency by means of Global Positioning System (GPS), Global Satellite Navigation System (GLONASS), MILSTAR, LORAN, and synchronous communications satellites.

Positioning navigation and timing service applications in cyber physical systems

NASA Astrophysics Data System (ADS)

Qu, Yi; Wu, Xiaojing; Zeng, Lingchuan

2017-10-01

The positioning navigation and timing (PNT) architecture was discussed in detail, whose history, evolvement, current status and future plan were presented, main technologies were listed, advantages and limitations of most technologies were compared, novel approaches were introduced, and future capacities were sketched. The concept of cyber-physical system (CPS) was described and their primary features were interpreted. Then the three-layer architecture of CPS was illustrated. Next CPS requirements on PNT services were analyzed, including requirements on position reference and time reference, requirements on temporal-spatial error monitor, requirements on dynamic services, real-time services, autonomous services, security services and standard services. Finally challenges faced by PNT applications in CPS were concluded. The conclusion was expected to facilitate PNT applications in CPS, and furthermore to provide references to the design and implementation of both architectures.

SLS Block 1-B and Exploration Upper Stage Navigation System Design

NASA Technical Reports Server (NTRS)

Oliver, T. Emerson; Park, Thomas B.; Smith, Austin; Anzalone, Evan; Bernard, Bill; Strickland, Dennis; Geohagan, Kevin; Green, Melissa; Leggett, Jarred

2018-01-01

The SLS Block 1B vehicle is planned to extend NASA's heavy lift capability beyond the initial SLS Block 1 vehicle. The most noticeable change for this vehicle from SLS Block 1 is the swapping of the upper stage from the Interim Cryogenic Propulsion stage (ICPS), a modified Delta IV upper stage, to the more capable Exploration Upper Stage (EUS). As the vehicle evolves to provide greater lift capability and execute more demanding missions so must the SLS Integrated Navigation System to support those missions. The SLS Block 1 vehicle carries two independent navigation systems. The responsibility of the two systems is delineated between ascent and upper stage flight. The Block 1 navigation system is responsible for the phase of flight between the launch pad and insertion into Low-Earth Orbit (LEO). The upper stage system assumes the mission from LEO to payload separation. For the Block 1B vehicle, the two functions are combined into a single system intended to navigate from ground to payload insertion. Both are responsible for self-disposal once payload delivery is achieved. The evolution of the navigation hardware and algorithms from an inertial-only navigation system for Block 1 ascent flight to a tightly coupled GPS-aided inertial navigation system for Block 1-B is described. The Block 1 GN&C system has been designed to meet a LEO insertion target with a specified accuracy. The Block 1-B vehicle navigation system is designed to support the Block 1 LEO target accuracy as well as trans-lunar or trans-planetary injection accuracy. This is measured in terms of payload impact and stage disposal requirements. Additionally, the Block 1-B vehicle is designed to support human exploration and thus is designed to minimize the probability of Loss of Crew (LOC) through high-quality inertial instruments and Fault Detection, Isolation, and Recovery (FDIR) logic. The preliminary Block 1B integrated navigation system design is presented along with the challenges associated with meeting the design objectives. This paper also addresses the design considerations associated with the use of Block 1 and Commercial Off-the-Shelf (COTS) avionics for Block 1-B/EUS as part of an integrated vehicle suite for orbital operations.

2001 Flight Mechanics Symposium

NASA Technical Reports Server (NTRS)

Lynch, John P. (Editor)

2001-01-01

This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium held on June 19-21, 2001. Sponsored by the Guidance, Navigation and Control Center of Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to attitude/orbit determination, prediction and control; attitude simulation; attitude sensor calibration; theoretical foundation of attitude computation; dynamics model improvements; autonomous navigation; constellation design and formation flying; estimation theory and computational techniques; Earth environment mission analysis and design; and, spacecraft re-entry mission design and operations.

Saturating effects of species diversity on life-history evolution in bacteria.

PubMed

Fiegna, Francesca; Scheuerl, Thomas; Moreno-Letelier, Alejandra; Bell, Thomas; Barraclough, Timothy G

2015-09-22

Species interactions can play a major role in shaping evolution in new environments. In theory, species interactions can either stimulate evolution by promoting coevolution or inhibit evolution by constraining ecological opportunity. The relative strength of these effects should vary as species richness increases, and yet there has been little evidence for evolution of component species in communities. We evolved bacterial microcosms containing between 1 and 12 species in three different environments. Growth rates and yields of isolates that evolved in communities were lower than those that evolved in monocultures, consistent with recent theory that competition constrains species to specialize on narrower sets of resources. This effect saturated or reversed at higher levels of richness, consistent with theory that directional effects of species interactions should weaken in more diverse communities. Species varied considerably, however, in their responses to both environment and richness levels. Mechanistic models and experiments are now needed to understand and predict joint evolutionary dynamics of species in diverse communities. © 2015 The Authors.

Copernican Astronomy and Oceanic Exploration

NASA Astrophysics Data System (ADS)

McKittrick, Paul

2014-01-01

This paper examines the relationships between the century long development of the “New Astronomy” (Copernicus’ axially rotating and solar orbiting earth, governed by Kepler’s laws of planetary motion) of the sixteenth and early seventeenth centuries and the emerging astronomical navigation technologies of the fifteenth and sixteenth century Iberian oceanic explorers and their sixteenth and seventeenth century Protestant competitors. Since the first breakthroughs in Portuguese astronomical navigation in ascertaining latitude at sea were based upon the theories and observations of classically trained Ptolemaic astronomers and cosmographers, it can be argued that the new heliocentric astronomy was not necessary for future developments in early modern navigation. By examining the history of the concurrent revolutions in early modern navigation and astronomy and focusing upon commonalities, we can identify the period during which the old astronomy provided navigators with insufficient results - perhaps hastening the acceptance of the new epistemology championed by Galileo and rejected by Bellarmine. Even though this happened during the period of northern protestant ascendancy in exploration, its roots can be seen during pre-Copernican acceptance in both Lutheran and Catholic Europe. Copernican mathematics was used to calculate Reinhold’s Prutenic Tables despite the author’s ontological rejection of the heliocentric hypothesis. These tables became essential for ascertaining latitude at sea. Kepler’s Rudophine Tables gained even more widespread currency across Europe. His theories were influenced by Gilbert’s work on magnetism - a work partially driven by the requirements of English polar exploration. Sailors themselves never needed to accept a heliocentric cosmography, but the data they brought back to the metropolis undermined Ptolemy, as better data kept them alive at sea. This exchange between theoretician and user in the early modern period drove both ships and science. Copernican astronomers and the great explorers had reciprocal debts.

Learners' strategies for reconstructing cognitive frameworks and navigating conceptual change from prior conception to consensual genetics knowledge

NASA Astrophysics Data System (ADS)

Parrott, Annette M.

Problem. Science teachers are charged with preparing students to become scientifically literate individuals. Teachers are given curriculum that specifies the knowledge that students should come away with; however, they are not necessarily aware of the knowledge with which the student arrives or how best to help them navigate between the two knowledge states. Educators must be aware, not only of where their students are conceptually, but how their students move from their prior knowledge and naive theories, to scientifically acceptable theories. The understanding of how students navigate this course has the potential to revolutionize educational practices. Methods. This study explored how five 9th grade biology students reconstructed their cognitive frameworks and navigated conceptual change from prior conception to consensual genetics knowledge. The research questions investigated were: (1) how do students in the process of changing their naive science theories to accepted science theories describe their journey from prior knowledge to current conception, and (2) what are the methods that students utilize to bridge the gap between alternate and consensual science conceptions to effect conceptual change. Qualitative and quantitative methods were employed to gather and analyze the data. In depth, semi-structured interviews formed the primary data for probing the context and details of students' conceptual change experience. Primary interview data was coded by thematic analysis. Results and discussion. This study revealed information about students' perceived roles in learning, the role of articulation in the conceptual change process, and ways in which a community of learners aids conceptual change. It was ascertained that students see their role in learning primarily as repeating information until they could add that information to their knowledge. Students are more likely to consider challenges to their conceptual frameworks and be more motivated to become active participants in constructing their knowledge when they are working collaboratively with peers instead of receiving instruction from their teacher. Articulation was found to be instrumental in aiding learners in identifying their alternate conceptions as well as in revisiting, investigating and reconstructing their conceptual frameworks. Based on the assumptions generated, suggestions were offered to inform pedagogical practice in support of the conceptual change process.

Nonhuman genetics. Genomic basis for the convergent evolution of electric organs.

PubMed

Gallant, Jason R; Traeger, Lindsay L; Volkening, Jeremy D; Moffett, Howell; Chen, Po-Hao; Novina, Carl D; Phillips, George N; Anand, Rene; Wells, Gregg B; Pinch, Matthew; Güth, Robert; Unguez, Graciela A; Albert, James S; Zakon, Harold H; Samanta, Manoj P; Sussman, Michael R

2014-06-27

Little is known about the genetic basis of convergent traits that originate repeatedly over broad taxonomic scales. The myogenic electric organ has evolved six times in fishes to produce electric fields used in communication, navigation, predation, or defense. We have examined the genomic basis of the convergent anatomical and physiological origins of these organs by assembling the genome of the electric eel (Electrophorus electricus) and sequencing electric organ and skeletal muscle transcriptomes from three lineages that have independently evolved electric organs. Our results indicate that, despite millions of years of evolution and large differences in the morphology of electric organ cells, independent lineages have leveraged similar transcription factors and developmental and cellular pathways in the evolution of electric organs. Copyright © 2014, American Association for the Advancement of Science.

Economic contract theory tests models of mutualism.

PubMed

Weyl, E Glen; Frederickson, Megan E; Yu, Douglas W; Pierce, Naomi E

2010-09-07

Although mutualisms are common in all ecological communities and have played key roles in the diversification of life, our current understanding of the evolution of cooperation applies mostly to social behavior within a species. A central question is whether mutualisms persist because hosts have evolved costly punishment of cheaters. Here, we use the economic theory of employment contracts to formulate and distinguish between two mechanisms that have been proposed to prevent cheating in host-symbiont mutualisms, partner fidelity feedback (PFF) and host sanctions (HS). Under PFF, positive feedback between host fitness and symbiont fitness is sufficient to prevent cheating; in contrast, HS posits the necessity of costly punishment to maintain mutualism. A coevolutionary model of mutualism finds that HS are unlikely to evolve de novo, and published data on legume-rhizobia and yucca-moth mutualisms are consistent with PFF and not with HS. Thus, in systems considered to be textbook cases of HS, we find poor support for the theory that hosts have evolved to punish cheating symbionts; instead, we show that even horizontally transmitted mutualisms can be stabilized via PFF. PFF theory may place previously underappreciated constraints on the evolution of mutualism and explain why punishment is far from ubiquitous in nature.

Cooperative behavior and phase transitions in co-evolving stag hunt game

NASA Astrophysics Data System (ADS)

Zhang, W.; Li, Y. S.; Xu, C.; Hui, P. M.

2016-02-01

Cooperative behavior and different phases in a co-evolving network dynamics based on the stag hunt game is studied. The dynamical processes are parameterized by a payoff r that tends to promote non-cooperative behavior and a probability q for a rewiring attempt that could isolate the non-cooperators. The interplay between the parameters leads to different phases. Detailed simulations and a mean field theory are employed to reveal the properties of different phases. For small r, the cooperators are the majority and form a connected cluster while the non-cooperators increase with q but remain isolated over the whole range of q, and it is a static phase. For sufficiently large r, cooperators disappear in an intermediate range qL ≤ q ≤qU and a dynamical all-non-cooperators phase results. For q >qU, a static phase results again. A mean field theory based on how the link densities change in time by the co-evolving dynamics is constructed. The theory gives a phase diagram in the q- r parameter space that is qualitatively in agreement with simulation results. The sources of discrepancies between theory and simulations are discussed.

Economic contract theory tests models of mutualism

PubMed Central

Weyl, E. Glen; Frederickson, Megan E.; Yu, Douglas W.; Pierce, Naomi E.

2010-01-01

Although mutualisms are common in all ecological communities and have played key roles in the diversification of life, our current understanding of the evolution of cooperation applies mostly to social behavior within a species. A central question is whether mutualisms persist because hosts have evolved costly punishment of cheaters. Here, we use the economic theory of employment contracts to formulate and distinguish between two mechanisms that have been proposed to prevent cheating in host–symbiont mutualisms, partner fidelity feedback (PFF) and host sanctions (HS). Under PFF, positive feedback between host fitness and symbiont fitness is sufficient to prevent cheating; in contrast, HS posits the necessity of costly punishment to maintain mutualism. A coevolutionary model of mutualism finds that HS are unlikely to evolve de novo, and published data on legume–rhizobia and yucca–moth mutualisms are consistent with PFF and not with HS. Thus, in systems considered to be textbook cases of HS, we find poor support for the theory that hosts have evolved to punish cheating symbionts; instead, we show that even horizontally transmitted mutualisms can be stabilized via PFF. PFF theory may place previously underappreciated constraints on the evolution of mutualism and explain why punishment is far from ubiquitous in nature. PMID:20733067

How Female Professionals Successfully Process and Negotiate Involuntary Job Loss at Faith-Based Colleges and Universities: A Grounded Theory Study

ERIC Educational Resources Information Center

Cunningham, Debra Jayne

2013-01-01

Using a constructivist grounded theory approach (Charmaz, 2006), this qualitative study examined how 8 female senior-level professionals employed at faith-based colleges and universities processed and navigated the experience of involuntary job loss and successfully transitioned to another position. The purpose of this research was to contribute…

Navigating the Tides of Change: Revisiting the Notion of Reflexivity in the Context of Social Learning for Transboundary Collective Experimentation

ERIC Educational Resources Information Center

Bastrup-Birk, Henriette; Wildemeersch, Danny

2011-01-01

Social learning theory in the context of multi-actor engagement tends to relate reflexivity primarily to critical questioning of theories-in-use. We argue that viewing suspensive dialogue and imaginative envisioning as additional stages of reflexivity will serve at least three purposes: prevent over-emphasis on instrumental rationality focusing on…

Pulsar Timing and Its Application for Navigation and Gravitational Wave Detection

NASA Astrophysics Data System (ADS)

Becker, Werner; Kramer, Michael; Sesana, Alberto

2018-02-01

Pulsars are natural cosmic clocks. On long timescales they rival the precision of terrestrial atomic clocks. Using a technique called pulsar timing, the exact measurement of pulse arrival times allows a number of applications, ranging from testing theories of gravity to detecting gravitational waves. Also an external reference system suitable for autonomous space navigation can be defined by pulsars, using them as natural navigation beacons, not unlike the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board a spacecraft with predicted pulse arrivals at a reference location (e.g. the solar system barycenter), the spacecraft position can be determined autonomously and with high accuracy everywhere in the solar system and beyond. We describe the unique properties of pulsars that suggest that such a navigation system will certainly have its application in future astronautics. We also describe the on-going experiments to use the clock-like nature of pulsars to "construct" a galactic-sized gravitational wave detector for low-frequency (f_{GW}˜ 10^{-9} - 10^{-7} Hz) gravitational waves. We present the current status and provide an outlook for the future.

Preface: High-rate GNSS: Theory, methods and engineering/geophysical applications

NASA Astrophysics Data System (ADS)

Xu, Peiliang

2017-06-01

Global Navigation Satellite Systems (GNSS) have revolutionized the science and engineering of positioning, timing and navigation and have become an indispensable means to rapidly obtain precise positioning-related information, profoundly affecting our daily life and infrastructure. With GNSS, the position of an object, either stationary or moving, can be determined anywhere, anytime and under any weather condition. In addition to providing a positioning and timing information service, GNSS are now also used to reconstruct physical properties of media through which GNSS signals travel. The utilization of additional GNSS systems such as the European Galileo and the Chinese Beidou (both expected to complete their final global constellations in 2020) will contribute to positioning/navigation science and engineering, provide more industrial opportunities and surely open more challenges.

Current use was established and Cochrane guidance on selection of social theories for systematic reviews of complex interventions was developed.

PubMed

Noyes, Jane; Hendry, Maggie; Booth, Andrew; Chandler, Jackie; Lewin, Simon; Glenton, Claire; Garside, Ruth

2016-07-01

To identify examples of how social theories are used in systematic reviews of complex interventions to inform production of Cochrane guidance. Secondary analysis of published/unpublished examples of theories of social phenomena for use in reviews of complex interventions identified through scoping searches, engagement with key authors and methodologists supplemented by snowballing and reference searching. Theories were classified (low-level, mid-range, grand). Over 100 theories were identified with evidence of proliferation over the last 5 years. New low-level theories (tools, taxonomies, etc) have been developed for classifying and reporting complex interventions. Numerous mid-range theories are used; one example demonstrated how control theory had changed the review's findings. Review-specific logic models are increasingly used, but these can be challenging to develop. New low-level and mid-range psychological theories of behavior change are evolving. No reviews using grand theory (e.g., feminist theory) were identified. We produced a searchable Wiki, Mendeley Inventory, and Cochrane guidance. Use of low-level theory is common and evolving; incorporation of mid-range theory is still the exception rather than the norm. Methodological work is needed to evaluate the contribution of theory. Choice of theory reflects personal preference; application of theory is a skilled endeavor. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

Evaluation of a conceptual framework for predicting navigation performance in virtual reality.

PubMed

Grübel, Jascha; Thrash, Tyler; Hölscher, Christoph; Schinazi, Victor R

2017-01-01

Previous research in spatial cognition has often relied on simple spatial tasks in static environments in order to draw inferences regarding navigation performance. These tasks are typically divided into categories (e.g., egocentric or allocentric) that reflect different two-systems theories. Unfortunately, this two-systems approach has been insufficient for reliably predicting navigation performance in virtual reality (VR). In the present experiment, participants were asked to learn and navigate towards goal locations in a virtual city and then perform eight simple spatial tasks in a separate environment. These eight tasks were organised along four orthogonal dimensions (static/dynamic, perceived/remembered, egocentric/allocentric, and distance/direction). We employed confirmatory and exploratory analyses in order to assess the relationship between navigation performance and performances on these simple tasks. We provide evidence that a dynamic task (i.e., intercepting a moving object) is capable of predicting navigation performance in a familiar virtual environment better than several categories of static tasks. These results have important implications for studies on navigation in VR that tend to over-emphasise the role of spatial memory. Given that our dynamic tasks required efficient interaction with the human interface device (HID), they were more closely aligned with the perceptuomotor processes associated with locomotion than wayfinding. In the future, researchers should consider training participants on HIDs using a dynamic task prior to conducting a navigation experiment. Performances on dynamic tasks should also be assessed in order to avoid confounding skill with an HID and spatial knowledge acquisition.

Evaluation of a conceptual framework for predicting navigation performance in virtual reality

PubMed Central

Thrash, Tyler; Hölscher, Christoph; Schinazi, Victor R.

2017-01-01

Previous research in spatial cognition has often relied on simple spatial tasks in static environments in order to draw inferences regarding navigation performance. These tasks are typically divided into categories (e.g., egocentric or allocentric) that reflect different two-systems theories. Unfortunately, this two-systems approach has been insufficient for reliably predicting navigation performance in virtual reality (VR). In the present experiment, participants were asked to learn and navigate towards goal locations in a virtual city and then perform eight simple spatial tasks in a separate environment. These eight tasks were organised along four orthogonal dimensions (static/dynamic, perceived/remembered, egocentric/allocentric, and distance/direction). We employed confirmatory and exploratory analyses in order to assess the relationship between navigation performance and performances on these simple tasks. We provide evidence that a dynamic task (i.e., intercepting a moving object) is capable of predicting navigation performance in a familiar virtual environment better than several categories of static tasks. These results have important implications for studies on navigation in VR that tend to over-emphasise the role of spatial memory. Given that our dynamic tasks required efficient interaction with the human interface device (HID), they were more closely aligned with the perceptuomotor processes associated with locomotion than wayfinding. In the future, researchers should consider training participants on HIDs using a dynamic task prior to conducting a navigation experiment. Performances on dynamic tasks should also be assessed in order to avoid confounding skill with an HID and spatial knowledge acquisition. PMID:28915266

Employee responsibility in benefit change.

PubMed

Hart, Deb; Arian, Mark

2007-01-01

If employers want to move employees beyond superficial acceptance of benefit changes, organizations need to increase the focus on how they manage the change process and support employee decision making. This article describes how employers can help workers understand changes and, through effective change management and communication, successfully navigate in an evolving benefits world. Using recent survey research about large employer and employee attitudes, the authors demonstrate tangible proof that these efforts pay off, both in financial and cultural terms.

Navigating the System: How Transgender Individuals Engage in Health Care Services.

PubMed

Roller, Cyndi Gale; Sedlak, Carol; Draucker, Claire Burke

2015-09-01

Transgender individuals (TIs) experience a number of healthcare disparities that result in compromised access to health care, placing them at high risk for poor health outcomes. Despite their unique health concerns, there is little known about how they engage in health care. The purpose of this grounded theory study was to construct a theoretical framework that depicts the process by which transgender individuals engage in health care. In this grounded theory study, data from interviews with 25 individuals who self-identified as transgender were used to develop a theoretical framework that depicts the process by which TIs engage in health care. Data analysis included open coding, category formation, and theoretical coding. Constant comparative analysis was used to facilitate theory generation. The central phenomenon of how TIs engage in health care was the core process of navigating the system. The core process involves four subprocesses: needing to move forward, doing due diligence, finding loopholes, and making it work. The theoretical framework of navigating the system can provide healthcare providers with a way to understand how TIs engage in health care as they move through the subprocesses of moving forward, doing due diligence, finding loopholes, and making it work in order to get their healthcare needs met. With a better understanding of the healthcare journeys of TIs, healthcare providers can provide better care for this population and advocate for change in policies that contribute to the health disparities TIs experience. © 2015 Sigma Theta Tau International.

Evolutionary robotics simulations help explain why reciprocity is rare in nature

PubMed Central

André, Jean-Baptiste; Nolfi, Stefano

2016-01-01

The relative rarity of reciprocity in nature, contrary to theoretical predictions that it should be widespread, is currently one of the major puzzles in social evolution theory. Here we use evolutionary robotics to solve this puzzle. We show that models based on game theory are misleading because they neglect the mechanics of behavior. In a series of experiments with simulated robots controlled by artificial neural networks, we find that reciprocity does not evolve, and show that this results from a general constraint that likely also prevents it from evolving in the wild. Reciprocity can evolve if it requires very few mutations, as is usually assumed in evolutionary game theoretic models, but not if, more realistically, it requires the accumulation of many adaptive mutations. PMID:27616139

Beyond Normativity in Sociocultural Reproduction and Sociocultural Transformation: Curriculum Work--Leadership within an Evolving Context

ERIC Educational Resources Information Center

Ylimaki, Rose M.; Fetman, Lisa J.; Matyjasik, Erin; Brunderman, Lynnette; Uljens, Michael

2017-01-01

Background: The purpose of this article is to examine the contributions, gaps, and normativity problems in mainstream sociocultural theories, curriculum theory, and educational leadership studies, considering reflective education theories that provide a less normative alternative. Framework: Our framework introduces reflective education for social…

Space Vehicle Guidance, Navigation, Control, and Estimation Operations Technologies

DTIC Science & Technology

2018-03-29

angular position around the ellipse, and the out-of-place amplitude and angular position. These elements are explicitly relatable to the six rectangular...quasi) second order relative orbital elements are explored. One theory uses the expanded solution form and introduces several instantaneous ellipses...In each case, the theory quantifies distortion of the first order relative orbital elements when including second order effects. The new variables are

Use of Cusp Catastrophe for Risk Analysis of Navigational Environment: A Case Study of Three Gorges Reservoir Area

PubMed Central

Hao, Guozhu

2016-01-01

A water traffic system is a huge, nonlinear, complex system, and its stability is affected by various factors. Water traffic accidents can be considered to be a kind of mutation of a water traffic system caused by the coupling of multiple navigational environment factors. In this study, the catastrophe theory, principal component analysis (PCA), and multivariate statistics are integrated to establish a situation recognition model for a navigational environment with the aim of performing a quantitative analysis of the situation of this environment via the extraction and classification of its key influencing factors; in this model, the natural environment and traffic environment are considered to be two control variables. The Three Gorges Reservoir area of the Yangtze River is considered as an example, and six critical factors, i.e., the visibility, wind, current velocity, route intersection, channel dimension, and traffic flow, are classified into two principal components: the natural environment and traffic environment. These two components are assumed to have the greatest influence on the navigation risk. Then, the cusp catastrophe model is employed to identify the safety situation of the regional navigational environment in the Three Gorges Reservoir area. The simulation results indicate that the situation of the navigational environment of this area is gradually worsening from downstream to upstream. PMID:27391057

A new systematic calibration method of ring laser gyroscope inertial navigation system

NASA Astrophysics Data System (ADS)

Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Xiong, Zhenyu; Long, Xingwu

2016-10-01

Inertial navigation system has been the core component of both military and civil navigation systems. Before the INS is put into application, it is supposed to be calibrated in the laboratory in order to compensate repeatability error caused by manufacturing. Discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed theories of error inspiration and separation in detail and presented a new systematic calibration method for ring laser gyroscope inertial navigation system. Error models and equations of calibrated Inertial Measurement Unit are given. Then proper rotation arrangement orders are depicted in order to establish the linear relationships between the change of velocity errors and calibrated parameter errors. Experiments have been set up to compare the systematic errors calculated by filtering calibration result with those obtained by discrete calibration result. The largest position error and velocity error of filtering calibration result are only 0.18 miles and 0.26m/s compared with 2 miles and 1.46m/s of discrete calibration result. These results have validated the new systematic calibration method and proved its importance for optimal design and accuracy improvement of calibration of mechanically dithered ring laser gyroscope inertial navigation system.

Use of Cusp Catastrophe for Risk Analysis of Navigational Environment: A Case Study of Three Gorges Reservoir Area.

PubMed

Jiang, Dan; Hao, Guozhu; Huang, Liwen; Zhang, Dan

2016-01-01

A water traffic system is a huge, nonlinear, complex system, and its stability is affected by various factors. Water traffic accidents can be considered to be a kind of mutation of a water traffic system caused by the coupling of multiple navigational environment factors. In this study, the catastrophe theory, principal component analysis (PCA), and multivariate statistics are integrated to establish a situation recognition model for a navigational environment with the aim of performing a quantitative analysis of the situation of this environment via the extraction and classification of its key influencing factors; in this model, the natural environment and traffic environment are considered to be two control variables. The Three Gorges Reservoir area of the Yangtze River is considered as an example, and six critical factors, i.e., the visibility, wind, current velocity, route intersection, channel dimension, and traffic flow, are classified into two principal components: the natural environment and traffic environment. These two components are assumed to have the greatest influence on the navigation risk. Then, the cusp catastrophe model is employed to identify the safety situation of the regional navigational environment in the Three Gorges Reservoir area. The simulation results indicate that the situation of the navigational environment of this area is gradually worsening from downstream to upstream.

Evolving Organizational Structures in Special Education.

ERIC Educational Resources Information Center

McCarthy, Eileen F., Ed.; Sage, Daniel D., Ed.

The monograph addresses evolving organizational structures in special education from the perspectives of theory and practice. The initial paper, "Issues in Organizational Structure" (D. Sage), focuses on how the multiple units and operations of the special education system should be related and how the management authority and responsibility for…

Hubble Servicing Challenges Drive Innovation of Shuttle Rendezvous Techniques

NASA Technical Reports Server (NTRS)

Goodman, John L.; Walker, Stephen R.

2009-01-01

Hubble Space Telescope (HST) servicing, performed by Space Shuttle crews, has contributed to what is arguably one of the most successful astronomy missions ever flown. Both nominal and contingency proximity operations techniques were developed to enable successful servicing, while lowering the risk of damage to HST systems, and improve crew safety. Influencing the development of these techniques were the challenges presented by plume impingement and HST performance anomalies. The design of both the HST and the Space Shuttle was completed before the potential of HST contamination and structural damage by shuttle RCS jet plume impingement was fully understood. Relative navigation during proximity operations has been challenging, as HST was not equipped with relative navigation aids. Since HST reached orbit in 1990, proximity operations design for servicing missions has evolved as insight into plume contamination and dynamic pressure has improved and new relative navigation tools have become available. Servicing missions have provided NASA with opportunities to gain insight into servicing mission design and development of nominal and contingency procedures. The HST servicing experiences and lessons learned are applicable to other programs that perform on-orbit servicing and rendezvous, both human and robotic.

The primacy of the good midwife in midwifery services: an evolving theory of professionalism in midwifery.

PubMed

Halldorsdottir, Sigridur; Karlsdottir, Sigfridur Inga

2011-12-01

Theory is the acknowledged foundation to practise methodology, professional identity and growth of formalized knowledge. It has been noted that practice must not only be evidence-based but also theory-based. Hence, midwifery must be theory based because theories serve as a broad framework for practice and may also articulate the goals of a profession and core values. In this paper, an evolving theory on the empowerment of childbearing women is introduced, where the midwife's professionalism is central. The theory is synthesized from nine datasets and scholarly work, and then more than three hundred studies were reviewed for clarification and confirmation. According to the theory, the midwife's professionalism is constructed from five main aspects: The professional midwife cares for the childbearing woman and her family. This caring within the professional domain is seen as the core of midwifery. The professional midwife is professionally competent. This professional competence must always have primacy for the sake of safety of woman and child. The professional midwife has professional wisdom and knows how to apply it. Professional wisdom is a new concept used to denote the interplay of knowledge and experience. The professional midwife has interpersonal competence, is capable of empowering communication and positive partnership with the woman and her family. The professional midwife develops herself both personally and professionally, which is the prerequisite for true professionalism. This evolving theory must be regularly reconstructed in the light of current knowledge within midwifery. It is an attempt to identify and articulate the processes and components of the art and science of midwifery practice in an endeavour of continuing the discipline's development by assisting in the understanding and practice of creating further theoretical discourse, processes and products for midwifery practice. The theory has implications for midwifery education and practice. © 2011 The Authors. Scandinavian Journal of Caring Sciences © 2011 Nordic College of Caring Science.

Transactional Distance and Dialogue: An Exploratory Study to Refine the Theoretical Construct of Dialogue in Online Learning

ERIC Educational Resources Information Center

Shearer, Rick L.

2009-01-01

Theory building is complex and ongoing. Theories need to be constantly tested and the underlying constructs explored, as knowledge of a field evolves. This study, which is in support of Moore's (1980, 1993) theory of transactional distance, is exploratory and descriptive, and focuses on one of the key variables in the theory dialogue. As…

A Neo-Piagetian Theory of Constructive Operators: Applications to Perceptual-Motor Development and Learning.

ERIC Educational Resources Information Center

Todor, John I.

The author presents an overview of Pascual-Leone's Theory of Constructive Operators, a process-structural theory based upon Piagetian constructs which has evolved to both explain and predict the temporal unfolding of behavior. An application is made of the theory to the demands of a discrete motor task and prediction of (a) the minimal age…

A Meta-Analysis of Institutional Theories

DTIC Science & Technology

1989-06-01

GPOUP SUBGROUP Institutional Theory , Isomorphism, Administrative Difterpntiation, Diffusion of Change, Rational, Unit Of Analysis 19 ABSTRACT (Continue on... institutional theory may lead to better decision making and evaluation criteria on the part of managers in the non-profit sector. C. SCOPE This paper... institutional theory : I) Organizations evolving in environments with elabora- ted institutional rules create structure that conform to those rules. 2

Socio-ecological influences on health-care access and navigation among persons of Mexican descent living on the U.S./Mexico border.

PubMed

Reininger, Belinda M; Barroso, Cristina S; Mitchell-Bennett, Lisa; Chavez, Marge; Fernandez, Maria E; Cantu, Ethel; Smith, Kirk L; Fisher-Hoch, Susan P

2014-04-01

The study reported here examines factors influencing decision-making concerning health care access and navigation among persons of Mexican origin living along the U.S./Mexico border. Specifically, the study examined how persons with limited financial resources accessed these two systems. Seven focus groups were held with 52 low income Mexican American people aged 18-65 years. Transcripts were analyzed to identify themes in Atlasti 5.0 software and the theory used included a socio-ecological framework and complemented by constructed from the Social Cognitive Theory. We found that in addition to a lack of insurance and financial resources to pay for health care; fear, embarrassment and denial associated with a diagnosis of illness; poor medical personnel interactions, and desire for quality but streamlined health care also influenced decision making. This theory-based study raises important issues if health care is to improve the health and welfare of disadvantaged populations and points to the need for greater focus on medical homes and prevention and early intervention approaches.

Socio-ecological Influences on Health-Care Access and Navigation Among Persons of Mexican Descent Living on the U.S./Mexico Border

PubMed Central

Barroso, Cristina S.; Mitchell-Bennett, Lisa; Chavez, Marge; Fernandez, Maria E.; Cantu, Ethel; Smith, Kirk L.; Fisher-Hoch, Susan P.

2013-01-01

The study reported here examines factors influencing decision-making concerning health care access and navigation among persons of Mexican origin living along the U.S./Mexico border. Specifically, the study examined how persons with limited financial resources accessed these two systems. Seven focus groups were held with 52 low income Mexican American people aged 18–65 years. Transcripts were analyzed to identify themes in Atlasti 5.0 software and the theory used included a socio-ecological framework and complemented by constructed from the Social Cognitive Theory. We found that in addition to a lack of insurance and financial resources to pay for health care; fear, embarrassment and denial associated with a diagnosis of illness; poor medical personnel interactions, and desire for quality but streamlined health care also influenced decision making. This theory-based study raises important issues if health care is to improve the health and welfare of disadvantaged populations and points to the need for greater focus on medical homes and prevention and early intervention approaches. PMID:23011576

Systemic Operational Design: Epistemological Bumpf or the Way Ahead for Operational Design?

DTIC Science & Technology

2006-05-25

facilitating the design of such architectural frames (meta-concepts), they are doomed to be trapped in a simplistic structuralist approach.”1...systems theory and complexity theory . SOD emerged and evolved in response to inherent challenges in the contemporary Israeli security environment...discussed in subsequent chapters. Theory . Theory is critical to this examination of the CEOD approach and SOD because theory underpins and informs

Experiments in autonomous robotics

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

Hamel, W.R.

1987-01-01

The Center for Engineering Systems Advanced Research (CESAR) is performing basic research in autonomous robotics for energy-related applications in hazardous environments. The CESAR research agenda includes a strong experimental component to assure practical evaluation of new concepts and theories. An evolutionary sequence of mobile research robots has been planned to support research in robot navigation, world sensing, and object manipulation. A number of experiments have been performed in studying robot navigation and path planning with planar sonar sensing. Future experiments will address more complex tasks involving three-dimensional sensing, dexterous manipulation, and human-scale operations.

Sensors and sensor systems for guidance and navigation II; Proceedings of the Meeting, Orlando, FL, Apr. 22, 23, 1992

NASA Astrophysics Data System (ADS)

Welch, Sharon S.

Topics discussed in this volume include aircraft guidance and navigation, optics for visual guidance of aircraft, spacecraft and missile guidance and navigation, lidar and ladar systems, microdevices, gyroscopes, cockpit displays, and automotive displays. Papers are presented on optical processing for range and attitude determination, aircraft collision avoidance using a statistical decision theory, a scanning laser aircraft surveillance system for carrier flight operations, star sensor simulation for astroinertial guidance and navigation, autonomous millimeter-wave radar guidance systems, and a 1.32-micron long-range solid state imaging ladar. Attention is also given to a microfabricated magnetometer using Young's modulus changes in magnetoelastic materials, an integrated microgyroscope, a pulsed diode ring laser gyroscope, self-scanned polysilicon active-matrix liquid-crystal displays, the history and development of coated contrast enhancement filters for cockpit displays, and the effect of the display configuration on the attentional sampling performance. (For individual items see A93-28152 to A93-28176, A93-28178 to A93-28180)

Astronomical Methods in Aerial Navigation

NASA Technical Reports Server (NTRS)

Beij, K Hilding

1925-01-01

The astronomical method of determining position is universally used in marine navigation and may also be of service in aerial navigation. The practical application of the method, however, must be modified and adapted to conform to the requirements of aviation. Much of this work of adaptation has already been accomplished, but being scattered through various technical journals in a number of languages, is not readily available. This report is for the purpose of collecting under one cover such previous work as appears to be of value to the aerial navigator, comparing instruments and methods, indicating the best practice, and suggesting future developments. The various methods of determining position and their application and value are outlined, and a brief resume of the theory of the astronomical method is given. Observation instruments are described in detail. A complete discussion of the reduction of observations follows, including a rapid method of finding position from the altitudes of two stars. Maps and map cases are briefly considered. A bibliography of the subject is appended.

Vector-based navigation using grid-like representations in artificial agents.

PubMed

Banino, Andrea; Barry, Caswell; Uria, Benigno; Blundell, Charles; Lillicrap, Timothy; Mirowski, Piotr; Pritzel, Alexander; Chadwick, Martin J; Degris, Thomas; Modayil, Joseph; Wayne, Greg; Soyer, Hubert; Viola, Fabio; Zhang, Brian; Goroshin, Ross; Rabinowitz, Neil; Pascanu, Razvan; Beattie, Charlie; Petersen, Stig; Sadik, Amir; Gaffney, Stephen; King, Helen; Kavukcuoglu, Koray; Hassabis, Demis; Hadsell, Raia; Kumaran, Dharshan

2018-05-01

Deep neural networks have achieved impressive successes in fields ranging from object recognition to complex games such as Go 1,2 . Navigation, however, remains a substantial challenge for artificial agents, with deep neural networks trained by reinforcement learning 3-5 failing to rival the proficiency of mammalian spatial behaviour, which is underpinned by grid cells in the entorhinal cortex 6 . Grid cells are thought to provide a multi-scale periodic representation that functions as a metric for coding space 7,8 and is critical for integrating self-motion (path integration) 6,7,9 and planning direct trajectories to goals (vector-based navigation) 7,10,11 . Here we set out to leverage the computational functions of grid cells to develop a deep reinforcement learning agent with mammal-like navigational abilities. We first trained a recurrent network to perform path integration, leading to the emergence of representations resembling grid cells, as well as other entorhinal cell types 12 . We then showed that this representation provided an effective basis for an agent to locate goals in challenging, unfamiliar, and changeable environments-optimizing the primary objective of navigation through deep reinforcement learning. The performance of agents endowed with grid-like representations surpassed that of an expert human and comparison agents, with the metric quantities necessary for vector-based navigation derived from grid-like units within the network. Furthermore, grid-like representations enabled agents to conduct shortcut behaviours reminiscent of those performed by mammals. Our findings show that emergent grid-like representations furnish agents with a Euclidean spatial metric and associated vector operations, providing a foundation for proficient navigation. As such, our results support neuroscientific theories that see grid cells as critical for vector-based navigation 7,10,11 , demonstrating that the latter can be combined with path-based strategies to support navigation in challenging environments.

A Clustering-Based Approach to Enriching Code Foraging Environment.

PubMed

Niu, Nan; Jin, Xiaoyu; Niu, Zhendong; Cheng, Jing-Ru C; Li, Ling; Kataev, Mikhail Yu

2016-09-01

Developers often spend valuable time navigating and seeking relevant code in software maintenance. Currently, there is a lack of theoretical foundations to guide tool design and evaluation to best shape the code base to developers. This paper contributes a unified code navigation theory in light of the optimal food-foraging principles. We further develop a novel framework for automatically assessing the foraging mechanisms in the context of program investigation. We use the framework to examine to what extent the clustering of software entities affects code foraging. Our quantitative analysis of long-lived open-source projects suggests that clustering enriches the software environment and improves foraging efficiency. Our qualitative inquiry reveals concrete insights into real developer's behavior. Our research opens the avenue toward building a new set of ecologically valid code navigation tools.

Complexity Theory

USGS Publications Warehouse

Lee, William H K.

2016-01-01

A complex system consists of many interacting parts, generates new collective behavior through self organization, and adaptively evolves through time. Many theories have been developed to study complex systems, including chaos, fractals, cellular automata, self organization, stochastic processes, turbulence, and genetic algorithms.

Ethics and genomic medicine, how to navigate decisions in surgical oncology.

PubMed

Devon, Karen M; Lerner-Ellis, Jordan P; Ganai, Sabha; Angelos, Peter

2015-01-01

Using genetic information to make medical decisions and tailor treatments to individuals will likely provide major benefits and become an important part of health care. Surgical oncologists must ethically apply scientific genetic information in a complex and evolving environment to the benefit of their patients. In this review we address ethical issues associated with: indications for genetic testing, informed consent for testing and therapy, confidentiality, targeted therapy, prophylactic surgery, and genetic testing in children. © 2014 Wiley Periodicals, Inc.

Exploring the evolutionary mechanism of complex supply chain systems using evolving hypergraphs

NASA Astrophysics Data System (ADS)

Suo, Qi; Guo, Jin-Li; Sun, Shiwei; Liu, Han

2018-01-01

A new evolutionary model is proposed to describe the characteristics and evolution pattern of supply chain systems using evolving hypergraphs, in which nodes represent enterprise entities while hyperedges represent the relationships among diverse trades. The nodes arrive at the system in accordance with a Poisson process, with the evolving process incorporating the addition of new nodes, linking of old nodes, and rewiring of links. Grounded in the Poisson process theory and continuum theory, the stationary average hyperdegree distribution is shown to follow a shifted power law (SPL), and the theoretical predictions are consistent with the results of numerical simulations. Testing the impact of parameters on the model yields a positive correlation between hyperdegree and degree. The model also uncovers macro characteristics of the relationships among enterprises due to the microscopic interactions among individuals.

What Does God Know? Supernatural Agents' Access to Socially Strategic and Non-Strategic Information

ERIC Educational Resources Information Center

Purzycki, Benjamin G.; Finkel, Daniel N.; Shaver, John; Wales, Nathan; Cohen, Adam B.; Sosis, Richard

2012-01-01

Current evolutionary and cognitive theories of religion posit that supernatural agent concepts emerge from cognitive systems such as theory of mind and social cognition. Some argue that these concepts evolved to maintain social order by minimizing antisocial behavior. If these theories are correct, then people should process information about…

Reactors, Weapons, X-Rays, and Solar Panels: Using SCOT, Technological Frame, Epistemic Culture, and Actor Network Theory to Investigate Technology

ERIC Educational Resources Information Center

Sovacool, Benjamin K.

2006-01-01

The article explores how four different theories have been used to investigate technology. It highlights the worth and limitations of each theory and argues that an eclectic, ever-evolving approach to the study of technology is warranted. (Contains 1 table.)

An Institutional Theory Analysis of Charter Schools: Addressing Institutional Challenges to Scale

ERIC Educational Resources Information Center

Huerta, Luis A.; Zuckerman, Andrew

2009-01-01

This article presents a conceptual framework derived from institutional theory in sociology that offers two competing policy contexts in which charter schools operate--a bureaucratic frame versus a decentralized frame. An analysis of evolving charter school types based on three underlying theories of action is considered. As charter school leaders…

Looking Back To The Future Of Cyberspace Warfare

DTIC Science & Technology

2016-05-26

evolution of military theory in other military domains, one can see connections to the way in which cyberspace is evolving as well. 1S. SUBJECT...primary means of waging future conflicts with the term cyberwar being used. By analyzing history and the evolution of military theory in other...3 Historical Review of Military Theory

Architectural Design for a Mars Communications and Navigation Orbital Infrastructure

NASA Technical Reports Server (NTRS)

Ceasrone R. J.; Hastrup, R. C.; Bell, D. J.; Roncoli, R. B.; Nelson, K.

1999-01-01

The planet Mars has become the focus of an intensive series of missions that span decades of time, a wide array of international agencies and an evolution from robotics to humans. The number of missions to Mars at any one time, and over a period of time, is unprecedented in the annals of space exploration. To meet the operational needs of this exploratory fleet will require the implementation of new architectural concepts for communications and navigation. To this end, NASA's Jet Propulsion Laboratory has begun to define and develop a Mars communications and navigation orbital infrastructure. This architecture will make extensive use of assets at Mars, as well as use of traditional Earth-based assets, such as the Deep Space Network, DSN. Indeed, the total system can be thought of as an extension of DSN nodes and services to the Mars in-situ region. The concept has been likened to the beginnings of an interplanetary Internet that will bring the exploration of Mars right into our living rooms. The paper will begin with a high-level overview of the concept for the Mars communications and navigation infrastructure. Next, the mission requirements will be presented. These will include the relatively near-term needs of robotic landers, rovers, ascent vehicles, balloons, airplanes, and possibly orbiting, arriving and departing spacecraft. Requirements envisioned for the human exploration of Mars will also be described. The important Mars orbit design trades on telecommunications and navigation capabilities will be summarized, and the baseline infrastructure will be described. A roadmap of NASA's plan to evolve this infrastructure over time will be shown. Finally, launch considerations and delivery to Mars will be briefly treated.

Time Evolving Fission Chain Theory and Fast Neutron and Gamma-Ray Counting Distributions

DOE PAGES

Kim, K. S.; Nakae, L. F.; Prasad, M. K.; ...

2015-11-01

Here, we solve a simple theoretical model of time evolving fission chains due to Feynman that generalizes and asymptotically approaches the point model theory. The point model theory has been used to analyze thermal neutron counting data. This extension of the theory underlies fast counting data for both neutrons and gamma rays from metal systems. Fast neutron and gamma-ray counting is now possible using liquid scintillator arrays with nanosecond time resolution. For individual fission chains, the differential equations describing three correlated probability distributions are solved: the time-dependent internal neutron population, accumulation of fissions in time, and accumulation of leaked neutronsmore » in time. Explicit analytic formulas are given for correlated moments of the time evolving chain populations. The equations for random time gate fast neutron and gamma-ray counting distributions, due to randomly initiated chains, are presented. Correlated moment equations are given for both random time gate and triggered time gate counting. There are explicit formulas for all correlated moments are given up to triple order, for all combinations of correlated fast neutrons and gamma rays. The nonlinear differential equations for probabilities for time dependent fission chain populations have a remarkably simple Monte Carlo realization. A Monte Carlo code was developed for this theory and is shown to statistically realize the solutions to the fission chain theory probability distributions. Combined with random initiation of chains and detection of external quanta, the Monte Carlo code generates time tagged data for neutron and gamma-ray counting and from these data the counting distributions.« less

Co-evolving prisoner's dilemma: Performance indicators and analytic approaches

NASA Astrophysics Data System (ADS)

Zhang, W.; Choi, C. W.; Li, Y. S.; Xu, C.; Hui, P. M.

2017-02-01

Understanding the intrinsic relation between the dynamical processes in a co-evolving network and the necessary ingredients in formulating a reliable theory is an important question and a challenging task. Using two slightly different definitions of performance indicator in the context of a co-evolving prisoner's dilemma game, it is shown that very different cooperative levels result and theories of different complexity are required to understand the key features. When the payoff per opponent is used as the indicator (Case A), non-cooperative strategy has an edge and dominates in a large part of the parameter space formed by the cutting-and-rewiring probability and the strategy imitation probability. When the payoff from all opponents is used (Case B), cooperative strategy has an edge and dominates the parameter space. Two distinct phases, one homogeneous and dynamical and another inhomogeneous and static, emerge and the phase boundary in the parameter space is studied in detail. A simple theory assuming an average competing environment for cooperative agents and another for non-cooperative agents is shown to perform well in Case A. The same theory, however, fails badly for Case B. It is necessary to include more spatial correlation into a theory for Case B. We show that the local configuration approximation, which takes into account of the different competing environments for agents with different strategies and degrees, is needed to give reliable results for Case B. The results illustrate that formulating a proper theory requires both a conceptual understanding of the effects of the adaptive processes in the problem and a delicate balance between simplicity and accuracy.

Interactions of spatial strategies producing generalization gradient and blocking: A computational approach

PubMed Central

Dollé, Laurent; Chavarriaga, Ricardo

2018-01-01

We present a computational model of spatial navigation comprising different learning mechanisms in mammals, i.e., associative, cognitive mapping and parallel systems. This model is able to reproduce a large number of experimental results in different variants of the Morris water maze task, including standard associative phenomena (spatial generalization gradient and blocking), as well as navigation based on cognitive mapping. Furthermore, we show that competitive and cooperative patterns between different navigation strategies in the model allow to explain previous apparently contradictory results supporting either associative or cognitive mechanisms for spatial learning. The key computational mechanism to reconcile experimental results showing different influences of distal and proximal cues on the behavior, different learning times, and different abilities of individuals to alternatively perform spatial and response strategies, relies in the dynamic coordination of navigation strategies, whose performance is evaluated online with a common currency through a modular approach. We provide a set of concrete experimental predictions to further test the computational model. Overall, this computational work sheds new light on inter-individual differences in navigation learning, and provides a formal and mechanistic approach to test various theories of spatial cognition in mammals. PMID:29630600

Exploring health navigating design: momentary contentment in a cancer context

PubMed Central

Sandén, Ulrika; Harrysson, Lars; Thulesius, Hans; Nilsson, Fredrik

2017-01-01

ABSTRACT Purpose: The technocratic and medicalized model of healthcare is rarely optimal for patients. By connecting two different studies we explore the possibilities of increasing quality of life in cancer care. Methods: The first study captures survival strategies in a historically isolated Arctic village in Norway resulting in Momentary contentment theory, which emerged from analysing four years of participant observation and interview data. The second study conceptualizes everyday life of cancer patients based on in-depth interviews with 19 cancer patients; this was conceptualized as Navigating a new life situation. Both studies used classic grounded theory methodology. The connection between the studies is based on a health design approach. Results: We found a fit between cancer patients challenging life conditions and harsh everyday life in an Arctic village. Death, treatments and dependence have become natural parts of life where the importance of creating spaces-of-moments and a Sense of Safety is imminent to well-being. While the cancer patients are in a new life situation, the Arctic people show a natural ability to handle uncertainties. Conclusion: By innovation theories connected to design thinking, Momentary contentment theory modified to fit cancer care would eventually be a way to improve cancer patients’ quality of life. PMID:28911272

Mass-losing peculiar red giants - The comparison between theory and observations

NASA Technical Reports Server (NTRS)

Jura, M.

1989-01-01

The mass loss from evolved red giants is considered. It seems that red giants on the Asymptotic Giant Branch (AGB) are losing between 0.0003 and 0.0006 solar mass/sq kpc yr in the solar neighborhood. If all the main sequence stars between 1 and 5 solar masses ultimately evolve into white dwarfs with masses of 0.7 solar mass, the predicted mass loss rate in the solar neighborhood from these stars is 0.0008 solar mass/sq kpc yr. Although there are still uncertainties, it appears that there is no strong disagreement between theory and observation.

Self-calibrating pseudolite arrays: Theory and experiment

NASA Astrophysics Data System (ADS)

Lemaster, Edward Alan

Tasks envisioned for future-generation Mars rovers---sample collection, area survey, resource mining, habitat construction, etc.---will require greatly enhanced navigational capabilities over those possessed by the 1997 Mars Sojourner rover. Many of these tasks will involve cooperative efforts by multiple rovers and other agents, necessitating both high accuracy and the ability to share navigation information among different users. On Earth, satellite-based carrier-phase differential GPS provides a means of delivering centimeter-level, drift-free positioning to multiple users in contact with a reference base station. It would be highly desirable to have a similar navigational capability for use in Mars exploration. This research has originated a new local-area navigation system---a Self-Calibrating Pseudolite Array (SCPA)---that can provide centimeter-level localization to multiple rovers by utilizing GPS-based pseudolite transceivers deployed in a ground-based array. Such a system of localized beacons can replace or augment a system based on orbiting satellite transmitters. Previous pseudolite arrays have relied upon a priori information to survey the locations of the pseudolites, which must be accurately known to enable navigation within the array. In contrast, an SCPA does not rely upon other measurement sources to determine these pseudolite locations. This independence is a key requirement for autonomous deployment on Mars, and is accomplished through the use of GPS transceivers containing both transmit and receive components and through algorithms that utilize limited motion of a transceiver-bearing rover to determine the locations of the stationary transceivers. This dissertation describes the theory and operation of GPS transceivers, and how they can be used for navigation within a Self-Calibrating Pseudolite Array. It presents new algorithms that can be used to self-survey such arrays robustly using no a priori information, even under adverse conditions such as high-multipath environments. It then describes the experimental SCPA prototype developed at Stanford University and used in conjunction with the K9 Mars rover operated by NASA Ames Research Center. Using this experimental system, it provides experimental validation of both successful positioning using GPS transceivers and full calibration of an SCPA following deployment in an unknown configuration.

Flight Mechanics/Estimation Theory Symposium, 1989

NASA Technical Reports Server (NTRS)

Stengle, Thomas (Editor)

1989-01-01

Numerous topics in flight mechanics and estimation were discussed. Satellite attitude control, quaternion estimation, orbit and attitude determination, spacecraft maneuvers, spacecraft navigation, gyroscope calibration, spacecraft rendevous, and atmospheric drag model calculations for spacecraft lifetime prediction are among the topics covered.

Project Management Using Modern Guidance, Navigation and Control Theory

NASA Technical Reports Server (NTRS)

Hill, Terry

2010-01-01

The idea of control theory and its application to project management is not new, however literature on the topic and real-world applications is not as readily available and comprehensive in how all the principals of Guidance, Navigation and Control (GN&C) apply. This paper will address how the fundamental principals of modern GN&C Theory have been applied to NASA's Constellation Space Suit project and the results in the ability to manage the project within cost, schedule and budget. A s with physical systems, projects can be modeled and managed with the same guiding principles of GN&C as if it were a complex vehicle, system or software with time-varying processes, at times non-linear responses, multiple data inputs of varying accuracy and a range of operating points. With such systems the classic approach could be applied to small and well-defined projects; however with larger, multi-year projects involving multiple organizational structures, external influences and a multitude of diverse resources, then modern control theory is required to model and control the project. The fundamental principals of G N&C stated that a system is comprised of these basic core concepts: State, Behavior, Control system, Navigation system, Guidance and Planning Logic, Feedback systems. The state of a system is a definition of the aspects of the dynamics of the system that can change, such as position, velocity, acceleration, coordinate-based attitude, temperature, etc. The behavior of the system is more of what changes are possible rather than what can change, which is captured in the state of the system. The behavior of a system is captured in the system modeling and if properly done, will aid in accurate system performance prediction in the future. The Control system understands the state and behavior of the system and feedback systems to adjust the control inputs into the system. The Navigation system takes the multiple data inputs and based upon a priori knowledge of the input, will develop a statistical-based weighting of the input to determine where the system currently is located. Guidance and Planning logic of the system with the understanding of where it is (provided by the navigation system) will in turn determine where it needs to be and how to get there. Lastly, the system Feedback system is the right arm of the control system to allow it to affect change in the overall system and therefore it is critical to not only correctly identify the system feedback inputs but also the system response to the feedback inputs. And with any systems project it is critical that the objective of the system be clearly defined for not only planning but to be used to measure performance and to aid in the guidance of the system or project.

Exploring the Evolving Professional Identity of Novice School Counselors

ERIC Educational Resources Information Center

Bamgbose, Olamojiba Omolara

2017-01-01

The study employed a grounded theory approach to explore the evolving professional identity of novice school counselors. Participants, who are currently employed as school counselors at the elementary, middle, or high school level with 1-4 years' experience, were career changers from other helping professions and graduates from an intensive school…

Evolutionary psychology is compatible with equity feminism, but not with gender feminism: a reply to Eagly and Wood (2011).

PubMed

Kuhle, Barry X

2012-01-11

I comment on Eagly and Wood's biosocial constructionist evolutionary theory (2011; DOI: 10.1007/s11199-011-9949-9). Although this gender feminist theory allows for evolved physical differences between men and women and evolved psychological similarities for men and women, it fails to consider evolutionary accounts of psychological sex differences. I hypothesize that gender feminists' reluctance to acknowledge that evolution has left different fingerprints on men's and women's bodies and brains stems from two common misunderstandings of evolutionary psychology: the myth of immutability and the naturalistic fallacy. I conclude that although evolutionary psychology is eminently compatible with equity feminism, evolutionary psychology and feminist psychology will conflict as long as the latter adheres to gender feminism and its unwillingness to acknowledge the evidence for evolved psychological sex differences.  Gender feminism's dualistic view of evolution hinders the search for and understanding of the proximate and ultimate causes of inequality. Feminist psychology needs to evolve by embracing equity feminism, which has no a priori stance on the origin or existence of differences between the sexes.

Feminisms and Educational Research. Philosophy, Theory, and Educational Research Series

ERIC Educational Resources Information Center

Kohli, Wendy R.; Burbules, Nicholas C.

2011-01-01

Feminist theory has come a long way from its nascent beginnings--no longer can it be classified as "liberal," "socialist," or "radical." It has shaped and evolved to take on multiple meanings and forms, each distinct in its own perspective and theory. In "Feminisms and Educational Research," the authors explore the various forms of feminisms,…

What College Teachers Should Know about Memory: A Perspective from Cognitive Psychology

ERIC Educational Resources Information Center

Miller, Michelle D.

2011-01-01

Cognitive psychology has much to contribute to our understanding of the best ways to promote learning and memory in the college classroom. However, cognitive theory has evolved considerably in recent decades, and it is important for instructors to have an up-to-date understanding of these theories, particularly those--such as memory theories--that…

The role of pride in women with anorexia nervosa: A grounded theory study.

PubMed

Faija, Cintia L; Tierney, Stephanie; Gooding, Patricia A; Peters, Sarah; Fox, John R E

2017-12-01

Theory and clinical literature suggest that pride may play an important role in the maintenance of restrictive eating disorders. A grounded theory study explored experiences of, and reflections on, pride among women with a current or past diagnosis of anorexia nervosa. This is a qualitative study using grounded theory. Semistructured interviews were conducted with 21 women recruited from an eating disorder unit in England, and from a UK self-help organization. Grounded theory from a constructivist lens was used. Analysis involved coding, constant comparison, and memo-writing. Pride evolves over the course of anorexia nervosa. Two overarching conceptual categories were identified: 'pride becoming intertwined with anorexia' and 'pride during the journey towards recovery'. These categories encompassed different forms of pride: 'alluring pride', 'toxic pride', 'pathological pride', 'anorexia pride', 'shameful pride', 'recovery pride', and 'resilient pride'. Initially, pride contributed to self-enhancement and buffered negative emotions. As the condition progressed, pride became a challenge to health and interfered with motivation to change. During recovery, perceptions of pride altered as a healthy approach to living ensued. The evolving nature of pride plays a central role in development, maintenance, and treatment of anorexia nervosa. Understanding of pride and its role in psychotherapeutic work with this client group may increase motivation to change and promote recovery. Future work should investigate whether tackling pride in eating disorders increases treatment efficacy and reduces the risk of relapsing. Pride associated with anorexia appeared to evolve in nature. During early stages of the eating disorder, it stopped people from seeking help. Later on, it prevented them from seeing pride in healthy domains of life (outside anorexia). Over time, pride in anorexia became an overwhelming emotion that interfered with motivation to change. It is important for practitioners to assess and discuss pride in anorexia and its evolving nature during treatment. Understanding of pride and its role in psychotherapeutic work with this client group may increase motivation to change and promote recovery. © 2017 The British Psychological Society.

Exploring the Structure and Evolution of the Universe: Multi-Band Profiles of the Known Gamma-Ray Pulsars

NASA Technical Reports Server (NTRS)

1998-01-01

As summarized in this pamphlet, some of the far-reaching underlying issues to be addressed include: What is the origin of the universe and its destiny; Why is the universe lumpy; How did the known structures of the universe evolve; How do galaxies evolve; How do massive black holes grow; How did the elemental composition of the universe evolve; What is the structure and behavior of matter in the extreme; and Is Einstein's general relativity theory right.

Planning and navigation as active inference.

PubMed

Kaplan, Raphael; Friston, Karl J

2018-03-23

This paper introduces an active inference formulation of planning and navigation. It illustrates how the exploitation-exploration dilemma is dissolved by acting to minimise uncertainty (i.e. expected surprise or free energy). We use simulations of a maze problem to illustrate how agents can solve quite complicated problems using context sensitive prior preferences to form subgoals. Our focus is on how epistemic behaviour-driven by novelty and the imperative to reduce uncertainty about the world-contextualises pragmatic or goal-directed behaviour. Using simulations, we illustrate the underlying process theory with synthetic behavioural and electrophysiological responses during exploration of a maze and subsequent navigation to a target location. An interesting phenomenon that emerged from the simulations was a putative distinction between 'place cells'-that fire when a subgoal is reached-and 'path cells'-that fire until a subgoal is reached.

Clustering impact regime with shocks in freely evolving granular gas

NASA Astrophysics Data System (ADS)

Isobe, Masaharu

2017-06-01

A freely cooling granular gas without any external force evolves from the initial homogeneous state to the inhomogeneous clustering state, at which the energy decay deviates from the Haff's law. The asymptotic behavior of energy in the inelastic hard sphere model have been predicted by several theories, which are based on the mode coupling theory or extension of inelastic hard rods gas. In this study, we revisited the clustering regime of freely evolving granular gas via large-scale molecular dynamics simulation with up to 16.7 million inelastic hard disks. We found novel regime regarding on collisions between "clusters" spontaneously appearing after clustering regime, which can only be identified more than a few million particles system. The volumetric dilatation pattern of semicircular shape originated from density shock propagation are well characterized on the appearing of "cluster impact" during the aggregation process of clusters.

Electron Flow in Multiheme Bacterial Cytochromes is a Balancing Act Between Heme Electronic Interaction and Redox Potentials

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

Breuer, Marian; Rosso, Kevin M.; Blumberger, Jochen

The naturally widespread process of electron transfer from metal reducing bacteria to extracellular solid metal oxides entails unique biomolecular machinery optimized for long-range electron transport. To perform this function efficiently microorganisms have adapted multi-heme c-type cytochromes to arrange heme cofactors into wires that cooperatively span the cellular envelope, transmitting electrons along distances greater than 100 Angstroms. Implications and opportunities for bionanotechnological device design are self-evident. However, at the molecular level how these proteins shuttle electrons along their heme wires, navigating intraprotein intersections and interprotein interfaces effciently, remains a mystery so far inaccessible to experiment. To shed light on this criticalmore » topic, we carried out extensive computer simulations to calculate Marcus theory quantities for electron transfer along the ten heme cofactors in the recently crystallized outer membrane cytochrome MtrF. The combination of electronic coupling matrix elements with free energy calculations of heme redox potentials and reorganization energies for heme-to-heme electron transfer allows the step-wise and overall electron transfer rate to be estimated and understood in terms of structural and dynamical characteristics of the protein. By solving a master equation for electron hopping, we estimate an intrinsic, maximum possible electron flux through solvated MtrF of 104-105 s-1, consistent with recently measured rates for the related MtrCAB protein complex. Intriguingly, this flux must navigate thermodynamically uphill steps past low potential hemes. Our calculations show that the rapid electron transport through MtrF is the result of a clear correlation between heme redox potential and the strength of electronic coupling along the wire: Thermodynamically uphill steps occur only between electronically well connected stacked heme pairs. This suggests that the protein evolved to harbor low potential hemes, presumably necessary for reduction of certain soluble substrates, without slowing down electron ow. These findings are particularly profound in light of the apparently well conserved staggered cross heme wire structural motif in functionally related outer-membrane proteins.« less

SIRU utilization. Volume 1: Theory, development and test evaluation

NASA Technical Reports Server (NTRS)

Musoff, H.

1974-01-01

The theory, development, and test evaluations of the Strapdown Inertial Reference Unit (SIRU) are discussed. The statistical failure detection and isolation, single position calibration, and self alignment techniques are emphasized. Circuit diagrams of the system components are provided. Mathematical models are developed to show the performance characteristics of the subsystems. Specific areas of the utilization program are identified as: (1) error source propagation characteristics and (2) local level navigation performance demonstrations.

Intermodality in Teaching Writing

ERIC Educational Resources Information Center

Christensen, Margarette

2012-01-01

This dissertation articulates a writing pedagogy based on a theory of "intermodality" to help writing instructors navigate the affordances and challenges of multimodal composition. Drawing from recent discoveries in neuroscience about how the brain makes meaning, I situate this pedagogy of intermodality--literally, "between the…

The Evolving Private Military Sector: A Survey

DTIC Science & Technology

2009-08-05

enough evidence (for instance, the diversification of commercial security firms into the PM sector) and enough theory (for instance, institutional ... theory about how new fields are created out of old ones, how legitimacy is co-opted) to suggest this perspective might warrant further investigation

Reconceptualizing Learning as a Dynamical System.

ERIC Educational Resources Information Center

Ennis, Catherine D.

1992-01-01

Dynamical systems theory can increase our understanding of the constantly evolving learning process. Current research using experimental and interpretive paradigms focuses on describing the attractors and constraints stabilizing the educational process. Dynamical systems theory focuses attention on critical junctures in the learning process as…

The faculty of language: what is it, who has it, and how did it evolve?

PubMed

Hauser, Marc D; Chomsky, Noam; Fitch, W Tecumseh

2002-11-22

We argue that an understanding of the faculty of language requires substantial interdisciplinary cooperation. We suggest how current developments in linguistics can be profitably wedded to work in evolutionary biology, anthropology, psychology, and neuroscience. We submit that a distinction should be made between the faculty of language in the broad sense (FLB) and in the narrow sense (FLN). FLB includes a sensory-motor system, a conceptual-intentional system, and the computational mechanisms for recursion, providing the capacity to generate an infinite range of expressions from a finite set of elements. We hypothesize that FLN only includes recursion and is the only uniquely human component of the faculty of language. We further argue that FLN may have evolved for reasons other than language, hence comparative studies might look for evidence of such computations outside of the domain of communication (for example, number, navigation, and social relations).

Selective Attention and Control of Action: Comparative Psychology of an Artificial, Evolved Agent and People

ERIC Educational Resources Information Center

Ward, Robert; Ward, Ronnie

2008-01-01

This study examined the selective attention abilities of a simple, artificial, evolved agent and considered implications of the agent's performance for theories of selective attention and action. The agent processed two targets in continuous time, catching one and then the other. This task required many cognitive operations, including prioritizing…

The Current Status of Instructional Design Theories in Relation to Today's Authoring Systems

ERIC Educational Resources Information Center

O'Neil, A. Fred

2008-01-01

It is of course very difficult to accurately project important characteristics of the future state of any rapidly evolving field, and the field of authoring systems for computer-assisted instruction (CAI) is no exception. However, strong trends in evolving CAI systems of today would seem to indicate some important characteristics of the software…

The Prevalence of Performance Improvement as a Central Topic in the Professional Literature

ERIC Educational Resources Information Center

Guerra-Lopez, Ingrid

2012-01-01

The performance improvement field has evolved from the work of professionals seeking to improve performance in the workplace. Each time the field has evolved, it has done so by consistently expanding its scope and incorporating a broader performance context in line with its systems-theory roots. But just how much has performance improvement…

What's Past Is Prologue: The Evolving Paradigms of Student Affairs

ERIC Educational Resources Information Center

Taylor, Simone Himbeault

2008-01-01

The purpose of this article is to frame--and reframe--the work of student affairs. Evolving paradigms have defined and advanced this work, which is dedicated to total student development and the betterment of society. The article promotes integrative learning as a new framework for student affairs. This paradigm, grounded in theory, research, and…

Multivariate Epi-splines and Evolving Function Identification Problems

DTIC Science & Technology

2015-04-15

such extrinsic information as well as observed function and subgradient values often evolve in applications, we establish conditions under which the...previous study [30] dealt with compact intervals of IR. Splines are intimately tied to optimization problems through their variational theory pioneered...approxima- tion. Motivated by applications in curve fitting, regression, probability density estimation, variogram computation, financial curve construction

Viscoplasticity: A thermodynamic formulation

NASA Technical Reports Server (NTRS)

Freed, A. D.; Chaboche, J. L.

1989-01-01

A thermodynamic foundation using the concept of internal state variables is given for a general theory of viscoplasticity, as it applies to initially isotropic materials. Three fundamental internal state variables are admitted. They are: a tensor valued back stress for kinematic effects, and the scalar valued drag and yield strengths for isotropic effects. All three are considered to phenomenologically evolve according to competitive processes between strain hardening, strain induced dynamic recovery, and time induced static recovery. Within this phenomenological framework, a thermodynamically admissible set of evolution equations is put forth. This theory allows each of the three fundamental internal variables to be composed as a sum of independently evolving constituents.

What's on Your Mind? How Private Speech Mediates Cognition during Initial Non-Primary Language Learning

ERIC Educational Resources Information Center

Stafford, Catherine A.

2013-01-01

Vygotskian sociocultural theory of mind holds that language mediates thought. According to the theory, speech does not merely put completed thought into words; rather, it is a tool to refine thought as it evolves in real time. This study investigated from a sociocultural theory of mind perspective how nine beginning learners of Latin used private…

“Theory of Food” as a Neurocognitive Adaptation

PubMed Central

Allen, John S.

2011-01-01

Human adult cognition emerges over the course of development via the interaction of multiple critical neurocognitive networks. These networks evolved in response to various selection pressures, many of which were modified or intensified by the intellectual, technological, and socio-cultural environments that arose in connection with the evolution of genus Homo. Networks related to language and theory of mind clearly play an important role in adult cognition. Given the critical importance of food to both basic survival and cultural interaction, a “theory of food” (analogous to theory of mind) may represent another complex network essential for normal cognition. I propose that theory of food evolved as an internal, cognitive representation of our diets in our minds. Like other complex cognitive abilities, it relies on complex and overlapping dedicated neural networks that develop in childhood under familial and cultural influences. Normative diets are analogous to first languages in that they are acquired without overt teaching; they are also difficult to change or modify once a critical period in development is passed. Theory of food suggests that cognitive activities related to food may be cognitive enhancers, which could have implications for maintaining healthy brain function in aging. PMID:22262561

"Theory of food" as a neurocognitive adaptation.

PubMed

Allen, John S

2012-01-01

Human adult cognition emerges over the course of development via the interaction of multiple critical neurocognitive networks. These networks evolved in response to various selection pressures, many of which were modified or intensified by the intellectual, technological, and sociocultural environments that arose in connection with the evolution of genus Homo. Networks related to language and theory of mind clearly play an important role in adult cognition. Given the critical importance of food to both basic survival and cultural interaction, a "theory of food" (analogous to theory of mind) may represent another complex network essential for normal cognition. I propose that theory of food evolved as an internal, cognitive representation of our diets in our minds. Like other complex cognitive abilities, it relies on complex and overlapping dedicated neural networks that develop in childhood under familial and cultural influences. Normative diets are analogous to first languages in that they are acquired without overt teaching; they are also difficult to change or modify once a critical period in development is passed. Theory of food suggests that cognitive activities related to food may be cognitive enhancers, which could have implications for maintaining healthy brain function in aging. Copyright © 2012 Wiley Periodicals, Inc.

Vortex scaling ranges in two-dimensional turbulence

NASA Astrophysics Data System (ADS)

Burgess, B. H.; Dritschel, D. G.; Scott, R. K.

2017-11-01

We survey the role of coherent vortices in two-dimensional turbulence, including formation mechanisms, implications for classical similarity and inertial range theories, and characteristics of the vortex populations. We review early work on the spatial and temporal scaling properties of vortices in freely evolving turbulence and more recent developments, including a spatiotemporal scaling theory for vortices in the forced inverse energy cascade. We emphasize that Kraichnan-Batchelor similarity theories and vortex scaling theories are best viewed as complementary and together provide a more complete description of two-dimensional turbulence. In particular, similarity theory has a continued role in describing the weak filamentary sea between the vortices. Moreover, we locate both classical inertial and vortex scaling ranges within the broader framework of scaling in far-from-equilibrium systems, which generically exhibit multiple fixed point solutions with distinct scaling behaviour. We describe how stationary transport in a range of scales comoving with the dilatation of flow features, as measured by the growth in vortex area, constrains the vortex number density in both freely evolving and forced two-dimensional turbulence. The new theories for coherent vortices reveal previously hidden nontrivial scaling, point to new dynamical understanding, and provide a novel exciting window into two-dimensional turbulence.

Error Analysis System for Spacecraft Navigation Using the Global Positioning System (GPS)

NASA Technical Reports Server (NTRS)

Truong, S. H.; Hart, R. C.; Hartman, K. R.; Tomcsik, T. L.; Searl, J. E.; Bernstein, A.

1997-01-01

The Flight Dynamics Division (FDD) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) is currently developing improved space-navigation filtering algorithms to use the Global Positioning System (GPS) for autonomous real-time onboard orbit determination. In connection with a GPS technology demonstration on the Small Satellite Technology Initiative (SSTI)/Lewis spacecraft, FDD analysts and programmers have teamed with the GSFC Guidance, Navigation, and Control Branch to develop the GPS Enhanced Orbit Determination Experiment (GEODE) system. The GEODE system consists of a Kalman filter operating as a navigation tool for estimating the position, velocity, and additional states required to accurately navigate the orbiting Lewis spacecraft by using astrodynamic modeling and GPS measurements from the receiver. A parallel effort at the FDD is the development of a GPS Error Analysis System (GEAS) that will be used to analyze and improve navigation filtering algorithms during development phases and during in-flight calibration. For GEAS, the Kalman filter theory is extended to estimate the errors in position, velocity, and other error states of interest. The estimation of errors in physical variables at regular intervals will allow the time, cause, and effect of navigation system weaknesses to be identified. In addition, by modeling a sufficient set of navigation system errors, a system failure that causes an observed error anomaly can be traced and accounted for. The GEAS software is formulated using Object Oriented Design (OOD) techniques implemented in the C++ programming language on a Sun SPARC workstation. The Phase 1 of this effort is the development of a basic system to be used to evaluate navigation algorithms implemented in the GEODE system. This paper presents the GEAS mathematical methodology, systems and operations concepts, and software design and implementation. Results from the use of the basic system to evaluate navigation algorithms implemented on GEODE are also discussed. In addition, recommendations for generalization of GEAS functions and for new techniques to optimize the accuracy and control of the GPS autonomous onboard navigation are presented.

For Spacious Skies: Self-Separation with "Autonomous Flight Rules" in US Domestic Airspace

NASA Technical Reports Server (NTRS)

Wing, David J.; Cotton, William B.

2011-01-01

Autonomous Flight Rules (AFR) are proposed as a new set of operating regulations in which aircraft navigate on tracks of their choice while self-separating from traffic and weather. AFR would exist alongside Instrument and Visual Flight Rules (IFR and VFR) as one of three available flight options for any appropriately trained and qualified operator with the necessary certified equipment. Historically, ground-based separation services evolved by necessity as aircraft began operating in the clouds and were unable to see each other. Today, technologies for global precision navigation, emerging airborne surveillance, and onboard computing enable traffic conflict management to be fully integrated with navigation procedures onboard the aircraft. By self-separating, aircraft can operate with more flexibility and fewer flight restrictions than are required when using ground-based separation. The AFR concept proposes a practical means in which self-separating aircraft could share the same airspace as IFR and VFR aircraft without disrupting the ongoing processes of Air Traffic Control. The paper discusses the context and motivation for implementing self-separation in US domestic airspace. It presents a historical perspective on separation, the proposed way forward in AFR, the rationale behind mixed operations, and the expected benefits of AFR for the airspace user community.

Grief as pathology: The evolution of grief theory in psychology from Freud to the present.

PubMed

Granek, Leeat

2010-02-01

The emergence of grief as a topic worthy of psychological study is an early 20th century invention. Freud published his influential essay on mourning and melancholia in 1917. Since he proposed the concept of "grief work," contemporary psychologists have examined his theory empirically and have claimed that grief is a pathology that should be included within the psychological domain. How, and why, has grief theory evolved within the discipline of psychology in this way? In what ways do these changes in the understanding of grief coincide with other historical developments within the discipline? In this article, I trace the development of grief, originally conceived by Freud within a psychoanalytic and nonpathological framework, to the current conceptualization of grief within the disease model. I show how grief theory has evolved within the discipline of psychology to become (a) an object worthy of scientific study within the discipline, and subsequently, (b) a pathology to be privatized, specialized, and treated by mental health professionals.

The Emergence of Interdisciplinarity from Epistemological Thought

ERIC Educational Resources Information Center

Welch, James, IV

2011-01-01

Interdisciplinary studies has positioned itself as an innovative approach to comprehending, navigating, and transforming knowledge. The emphasis in recent scholarship upon complex systems and integration of insights from disciplinary perspectives mark decisive progress toward the development of a cohesive theory of interdisciplinarity. Such a…

Navigating the Path to a Biomedical Science Career

NASA Astrophysics Data System (ADS)

Zimmerman, Andrea McNeely

The number of biomedical PhD scientists being trained and graduated far exceeds the number of academic faculty positions and academic research jobs. If this trend is compelling biomedical PhD scientists to increasingly seek career paths outside of academia, then more should be known about their intentions, desires, training experiences, and career path navigation. Therefore, the purpose of this study was to understand the process through which biomedical PhD scientists are trained and supported for navigating future career paths. In addition, the study sought to determine whether career development support efforts and opportunities should be redesigned to account for the proportion of PhD scientists following non-academic career pathways. Guided by the social cognitive career theory (SCCT) framework this study sought to answer the following central research question: How does a southeastern tier 1 research university train and support its biomedical PhD scientists for navigating their career paths? Key findings are: Many factors influence PhD scientists' career sector preference and job search process, but the most influential were relationships with faculty, particularly the mentor advisor; Planned activities are a significant aspect of the training process and provide skills for career success; and Planned activities provided skills necessary for a career, but influential factors directed the career path navigated. Implications for practice and future research are discussed.

Navigating a strange and complex environment: experiences of Sudanese refugee women using a new nutrition resource

PubMed Central

Mannion, Cynthia A; Raffin-Bouchal, Shelley; Henshaw, Christena Jane

2014-01-01

Background Refugees experience dietary changes as part of the daily challenges they face resettling in a new country. Sudanese women seek to care and feed their families, but face language barriers in the marketplace, limited access to familiar foods, and forced new food choices. This study aimed to understand the acceptability of a purse-sized nutrition resource, “The Market Guide”, which was developed to help recently immigrated Sudanese refugee women identify and purchase healthy foods and navigate grocery stores. Methods Eight women participated in a focus group, four of whom were also observed during accompanied grocery store visits. Individual interviews were conducted with four health care workers at the resettlement center to gather perceptions about the suitability of The Market Guide. Focus groups and interviews were audiotaped and transcribed. Data from field notes and transcripts were analyzed using grounded theory for preliminary open codes, followed by selective and theoretical coding. Results The Market Guide was of limited use to Sudanese women. Their response to this resource revealed the struggles of women acculturating during their first year in Calgary, Canada. We discovered the basic social process, “Navigating through a strange and complex environment: learning ways to feed your family.” Language, transportation, and an unfamiliar marketplace challenged women and prevented them from exercising their customary role of “knowing” which foods were “safe and good” for their families. The nutrition resource fell short of informing food choices and purchases, and we discovered that “learning to feed your family” is a relational process where trusted persons, family, and friends help navigate dietary acculturation. Conclusion Emergent theory based on the basic social process may help health care professionals consider relational learning when planning health promotion and nutrition activities with Sudanese families. PMID:24790470

Sex differences in Nintendo Wii performance as expected from hunter-gatherer selection.

PubMed

Cherney, Isabelle D; Poss, Jordan L

2008-06-01

To test the hunter-gatherer theory of cognitive sex differences, men and women each played four video games on a Wii console: two games simulating skills necessary for hunting (navigation and shooting) and two games simulating skills necessary for gathering (fine motor and visual search). Men outperformed women on the two hunting games, whereas there were no sex differences on the gathering skill games. The findings are discussed in terms of evolutionary psychology theory.

Simple autonomous Mars walker

NASA Technical Reports Server (NTRS)

Larimer, Stanley J.; Lisec, Thomas R.; Spiessbach, Andrew J.

1989-01-01

Under a contract with NASA's Jet Propulsion Laboratory, Martin Marietta has developed several alternative rover concepts for unmanned exploration of the planet Mars. One of those concepts, the 'Walking Beam', is the subject of this paper. This concept was developed with the goal of achieving many of the capabilities of more sophisticated articulated-leg walkers with a much simpler, more robust, less computationally demanding and more power efficient design. It consists of two large-base tripods nested one within the other which alternately translate with respect to each other along a 5-meter beam to propel the vehicle. The semiautonomous navigation system relies on terrain geometry sensors and tacticle feedback from each foot to autonomously select a path which avoids hazards along a route designated from earth. Both mobility and navigation features of this concept are discussed including a top-level description of the vehicle's physical characteristics, deployment strategy, mobility elements, sensor suite, theory of operation, navigation and control processes, and estimated performance.

Navigation performance in virtual environments varies with fractal dimension of landscape.

PubMed

Juliani, Arthur W; Bies, Alexander J; Boydston, Cooper R; Taylor, Richard P; Sereno, Margaret E

2016-09-01

Fractal geometry has been used to describe natural and built environments, but has yet to be studied in navigational research. In order to establish a relationship between the fractal dimension (D) of a natural environment and humans' ability to navigate such spaces, we conducted two experiments using virtual environments that simulate the fractal properties of nature. In Experiment 1, participants completed a goal-driven search task either with or without a map in landscapes that varied in D. In Experiment 2, participants completed a map-reading and location-judgment task in separate sets of fractal landscapes. In both experiments, task performance was highest at the low-to-mid range of D, which was previously reported as most preferred and discriminable in studies of fractal aesthetics and discrimination, respectively, supporting a theory of visual fluency. The applicability of these findings to architecture, urban planning, and the general design of constructed spaces is discussed.

A joint tracking method for NSCC based on WLS algorithm

NASA Astrophysics Data System (ADS)

Luo, Ruidan; Xu, Ying; Yuan, Hong

2017-12-01

Navigation signal based on compound carrier (NSCC), has the flexible multi-carrier scheme and various scheme parameters configuration, which enables it to possess significant efficiency of navigation augmentation in terms of spectral efficiency, tracking accuracy, multipath mitigation capability and anti-jamming reduction compared with legacy navigation signals. Meanwhile, the typical scheme characteristics can provide auxiliary information for signal synchronism algorithm design. This paper, based on the characteristics of NSCC, proposed a kind of joint tracking method utilizing Weighted Least Square (WLS) algorithm. In this method, the LS algorithm is employed to jointly estimate each sub-carrier frequency shift with the frequency-Doppler linear relationship, by utilizing the known sub-carrier frequency. Besides, the weighting matrix is set adaptively according to the sub-carrier power to ensure the estimation accuracy. Both the theory analysis and simulation results illustrate that the tracking accuracy and sensitivity of this method outperforms the single-carrier algorithm with lower SNR.

A Comparison of Two Native American Navigator Formats: Face-to-Face and Telephone

PubMed Central

Dignan, Mark B.; Burhansstipanov, Linda; Hariton, Judy; Harjo, Lisa; Rattler, Jerri; Lee, Rose; Mason, Mondi

2012-01-01

The study was designed to test the relative effectiveness of a Navigator intervention delivered face-to-face or by telephone to urban Native American women. The effectiveness of the intervention was evaluated using a design that included a pretest, random assignment to face-to-face or telephone group, and posttest. The Social Cognitive Theory-based intervention was a tailored education program developed to address individual risk factors for breast cancer. At posttest, self-reported mammograms in the past year increased from 29% to 41.3% in the telephone group and from 34.4%: to 45.2% in the face-to-face group. There was no difference in change from pretest to posttest between the telephone and face-to-face groups. Navigators can be effective in increasing adherence to recommendations for screening mammography among urban American Indian women. PMID:16327748

Revisiting the Idea of "Critical Aspects"

ERIC Educational Resources Information Center

Pang, Ming Fai; Ki, Wing Wah

2016-01-01

Over the years, two new strands of research have evolved from the phenomenographic research tradition: the first concerns advancement of the variation theory of learning, whilst the second involves development of the learning study approach. In this paper, the conceptual frameworks of phenomenography, variation theory, and learning studies are…

REGIME CHANGES IN ECOLOGICAL SYSTEMS: AN INFORMATION THEORY APPROACH

EPA Science Inventory

We present our efforts at developing an ecological system using Information Theory. We derive an expression for Fisher Information based on sampling of the system trajectory as it evolves in the state space. The Fisher Information index as we have derived it captures the characte...

Olympic Values Education: Evolution of a Pedagogy

ERIC Educational Resources Information Center

Binder, Deanna L.

2012-01-01

Guided by the twentieth century hermeneutic idea that application co-determines understanding, this paper explores the conversations between theory and application that evolved during the implementation of three Olympic-related curriculum projects. Each of these projects was informed by specific fields of then-current educational theory, and…

COPEPOD REPRODUCTIVE STRATEGIES: LIFE-HISTORY THEORY, PHYLOGENETIC PATTERN AND INVASION OF INLAND WATERS. (R824771)

EPA Science Inventory

Abstract

Life-history theory predicts that different reproductive strategies should evolve in environments that differ in resource availability, mortality, seasonality, and in spatial or temporal variation. Within a population, the predicted optimal strategy is driven ...

Surgical navigation in urology: European perspective.

PubMed

Rassweiler, Jens; Rassweiler, Marie-Claire; Müller, Michael; Kenngott, Hannes; Meinzer, Hans-Peter; Teber, Dogu

2014-01-01

Use of virtual reality to navigate open and endoscopic surgery has significantly evolved during the last decade. Current status of seven most interesting projects inside the European Association of Urology section of uro-technology is summarized with review of literature. Marker-based endoscopic tracking during laparoscopic radical prostatectomy using high-definition technology reduces positive margins. Marker-based endoscopic tracking during laparoscopic partial nephrectomy by mechanical overlay of three-dimensional-segmented virtual anatomy is helpful during planning of trocar placement and dissection of renal hilum. Marker-based, iPAD-assisted puncture of renal collecting system shows more benefit for trainees with reduction of radiation exposure. Three-dimensional laser-assisted puncture of renal collecting system using Uro-Dyna-CT realized in an ex-vivo model enables minimal radiation time. Electromagnetic tracking for puncture of renal collecting system using a sensor at the tip of ureteral catheter worked in an in-vivo model of porcine ureter and kidney. Attitude tracking for ultrasound-guided puncture of renal tumours by accelerometer reduces the puncture error from 4.7 to 1.8 mm. Feasibility of electromagnetic and optical tracking with the da Vinci telemanipulator was shown in vitro as well as using in-vivo model of oesophagectomy. Target registration error was 11.2 mm because of soft-tissue deformation. Intraoperative navigation is helpful during percutaneous puncture collecting system and biopsy of renal tumour using various tracking techniques. Early clinical studies demonstrate advantages of marker-based navigation during laparoscopic radical prostatectomy and partial nephrectomy. Combination of different tracking techniques may further improve this interesting addition to video-assisted surgery.

A Hardware-in-the-Loop Testbed for Spacecraft Formation Flying Applications

NASA Technical Reports Server (NTRS)

Leitner, Jesse; Bauer, Frank H. (Technical Monitor)

2001-01-01

The Formation Flying Test Bed (FFTB) at NASA Goddard Space Flight Center (GSFC) is being developed as a modular, hybrid dynamic simulation facility employed for end-to-end guidance, navigation, and control (GN&C) analysis and design for formation flying clusters and constellations of satellites. The FFTB will support critical hardware and software technology development to enable current and future missions for NASA, other government agencies, and external customers for a wide range of missions, particularly those involving distributed spacecraft operations. The initial capabilities of the FFTB are based upon an integration of high fidelity hardware and software simulation, emulation, and test platforms developed at GSFC in recent years; including a high-fidelity GPS simulator which has been a fundamental component of the Guidance, Navigation, and Control Center's GPS Test Facility. The FFTB will be continuously evolving over the next several years from a too[ with initial capabilities in GPS navigation hardware/software- in-the- loop analysis and closed loop GPS-based orbit control algorithm assessment to one with cross-link communications and relative navigation analysis and simulation capability. Eventually the FFT13 will provide full capability to support all aspects of multi-sensor, absolute and relative position determination and control, in all (attitude and orbit) degrees of freedom, as well as information management for satellite clusters and constellations. In this paper we focus on the architecture for the FFT13 as a general GN&C analysis environment for the spacecraft formation flying community inside and outside of NASA GSFC and we briefly reference some current and future activities which will drive the requirements and development.

Oncology Nurse Navigation: Results of the 2016 Role Delineation Study.

PubMed

Lubejko, Barbara G; Bellfield, Sonia; Kahn, Elisa; Lee, Carrie; Peterson, Nicole; Rose, Traudi; Murphy, Cynthia Miller; McCorkle, Michele

2017-02-01

In 2011, an oncology nurse navigator (ONN) role delineation survey (RDS) was conducted by the Oncology Nursing Society (ONS) when the role was relatively new to oncology. Results did not demonstrate a unique skill set for the ONN; however, since then, the role has expanded. ONS and the Oncology Nursing Certification Corporation partnered in 2016 to complete an RDS of ONNs to redefine the role and determine the need for an ONN certification examination. A structured RDS was conducted using a formal consensus-building process. A survey was developed and released to examine the specific tasks, knowledge, and skills for the ONN as well as to determine which role possesses more responsibility for the tasks. The ONN role is evolving, and more was learned about its key tasks, including differences in the responsibilities of the ONN and the clinical or staff nurse. However, the RDS did not find an adequate difference in the knowledge required by the ONN and the clinical or staff nurse to support the need for a separate ONN certification.

Vertical Navigation Control Laws and Logic for the Next Generation Air Transportation System

NASA Technical Reports Server (NTRS)

Hueschen, Richard M.; Khong, Thuan H.

2013-01-01

A vertical navigation (VNAV) outer-loop control system was developed to capture and track the vertical path segments of energy-efficient trajectories that are being developed for high-density operations in the evolving Next Generation Air Transportation System (NextGen). The VNAV control system has a speed-on-elevator control mode to pitch the aircraft for tracking a calibrated airspeed (CAS) or Mach number profile and a path control mode for tracking the VNAV altitude profile. Mode control logic was developed for engagement of either the speed or path control modes. The control system will level the aircraft to prevent it from flying through a constraint altitude. A stability analysis was performed that showed that the gain and phase margins of the VNAV control system significantly exceeded the design gain and phase margins. The system performance was assessed using a six-deg-of-freedom non-linear transport aircraft simulation and the performance is illustrated with time-history plots of recorded simulation data.

A central role for the retrosplenial cortex in de novo environmental learning

PubMed Central

Auger, Stephen D; Zeidman, Peter; Maguire, Eleanor A

2015-01-01

With experience we become accustomed to the types of environments that we normally encounter as we navigate in the world. But how does this fundamental knowledge develop in the first place and what brain regions are involved? To examine de novo environmental learning, we created an ‘alien’ virtual reality world populated with landmarks of which participants had no prior experience. They learned about this environment by moving within it during functional MRI (fMRI) scanning while we tracked their evolving knowledge. Retrosplenial cortex (RSC) played a central and highly selective role by representing only the most stable, permanent features in this world. Subsequently, increased coupling was noted between RSC and hippocampus, with hippocampus then expressing knowledge of permanent landmark locations and overall environmental layout. Studying how environmental representations emerge from scratch provided a new window into the information processing underpinning the brain's navigation system, highlighting the key influence of the RSC. DOI: http://dx.doi.org/10.7554/eLife.09031.001 PMID:26284602

Neuronal connectome of a sensory-motor circuit for visual navigation

PubMed Central

Randel, Nadine; Asadulina, Albina; Bezares-Calderón, Luis A; Verasztó, Csaba; Williams, Elizabeth A; Conzelmann, Markus; Shahidi, Réza; Jékely, Gáspár

2014-01-01

Animals use spatial differences in environmental light levels for visual navigation; however, how light inputs are translated into coordinated motor outputs remains poorly understood. Here we reconstruct the neuronal connectome of a four-eye visual circuit in the larva of the annelid Platynereis using serial-section transmission electron microscopy. In this 71-neuron circuit, photoreceptors connect via three layers of interneurons to motorneurons, which innervate trunk muscles. By combining eye ablations with behavioral experiments, we show that the circuit compares light on either side of the body and stimulates body bending upon left-right light imbalance during visual phototaxis. We also identified an interneuron motif that enhances sensitivity to different light intensity contrasts. The Platynereis eye circuit has the hallmarks of a visual system, including spatial light detection and contrast modulation, illustrating how image-forming eyes may have evolved via intermediate stages contrasting only a light and a dark field during a simple visual task. DOI: http://dx.doi.org/10.7554/eLife.02730.001 PMID:24867217

Queering the Writing Center

ERIC Educational Resources Information Center

Denny, Harry

2010-01-01

Composition classrooms and writing centers are spaces where negotiation of academic, social, cultural, and political identities are ubiquitous, yet research has not produced adequate theory and practice to help tutors and writers navigate identity production and its politics. This article seeks to begin conversations that might lead to better…

Rationalizing Cooperation: Moroccan Craft, Politics, and Education

ERIC Educational Resources Information Center

Nicholas, Claire

2018-01-01

State attempts to rationalize Moroccan craft education reflect the ambivalent status of traditional knowledge in a modern economy. Female artisans, recently organized as a cooperative, navigate this ambivalence in a weaving "theory" class and in their "occupation" of the cooperative structure itself. During performances of…

"Going beyond the call of doula": a grounded theory analysis of the diverse roles community-based doulas play in the lives of pregnant and parenting adolescent mothers.

PubMed

Gentry, Quinn M; Nolte, Kim M; Gonzalez, Ainka; Pearson, Magan; Ivey, Symeon

2010-01-01

This article presents some of the most salient qualitative results from a larger program evaluation of pregnant and parenting adolescents who participated in a community-based doula program. Using grounded theory analysis, seven problem-solving strategies emerged that doulas apply in helping pregnant and parenting adolescents navigate multiple social and health settings that often serve as barriers to positive maternal- and child-health outcomes. The ethnographic findings of this study suggest that the doulas provide valuable assistance to pregnant and parenting adolescents by addressing social-psychological issues and socio-economic disparities. "Diverse role-taking" results in doulas helping pregnant adolescents navigate more successfully through fragmented social and health service systems that are less supportive of low-income adolescents, who are often perceived to be draining scarce resources. The findings have implications for the roles of community-based doulas assigned to low-income adolescents of color seeking to overcome obstacles and attain better educational and economic opportunities.

Design and realization of the baseband processor in satellite navigation and positioning receiver

NASA Astrophysics Data System (ADS)

Zhang, Dawei; Hu, Xiulin; Li, Chen

2007-11-01

The content of this paper is focused on the Design and realization of the baseband processor in satellite navigation and positioning receiver. Baseband processor is the most important part of the satellite positioning receiver. The design covers baseband processor's main functions include multi-channel digital signal DDC, acquisition, code tracking, carrier tracking, demodulation, etc. The realization is based on an Altera's FPGA device, that makes the system can be improved and upgraded without modifying the hardware. It embodies the theory of software defined radio (SDR), and puts the theory of the spread spectrum into practice. This paper puts emphasis on the realization of baseband processor in FPGA. In the order of choosing chips, design entry, debugging and synthesis, the flow is presented detailedly. Additionally the paper detailed realization of Digital PLL in order to explain a method of reducing the consumption of FPGA. Finally, the paper presents the result of Synthesis. This design has been used in BD-1, BD-2 and GPS.

Navigating Critical Theory and Postmodernism: Social Justice and Therapist Power in Family Therapy.

PubMed

D'Arrigo-Patrick, Justine; Hoff, Chris; Knudson-Martin, Carmen; Tuttle, Amy

2017-09-01

The family therapy field encourages commitment to diversity and social justice, but offers varying ideas about how to attentively consider these issues. Critical informed models advocate activism, whereas postmodern informed models encourage multiple perspectives. It is often not clear how activism and an emphasis on multiple perspectives connect, engendering the sense that critical and postmodern practices may be disparate. To understand how therapists negotiate these perspectives in practice, this qualitative grounded theory analysis drew on interviews with 11 therapists, each known for their work from both critical and postmodern perspectives. We found that these therapists generally engage in a set of shared constructionist practices while also demonstrating two distinct forms of activism: activism through countering and activism through collaborating. Ultimately, decisions made about how to navigate critical and postmodern influences were connected to how therapists viewed ethics and the ways they were comfortable using their therapeutic power. The findings illustrate practice strategies through which therapists apply each approach. © 2016 Family Process Institute.

From "Organisms" to "Boundaries": The Uneven Development of Theory Narratives in Education, Learning and Work Connections

ERIC Educational Resources Information Center

Saunders, Murray

2006-01-01

This paper uses the metaphor of a "theory narrative" to discuss the way in which the connections between education, learning and work have been understood. It identifies six theory narratives, and analyses each in turn, leading to an overview that suggests the way in which these explanatory frameworks might evolve in the future. The six narratives…

Reflexive Control in Operational Art: Designing Emergent Opportunity in the Vicksburg Campaign

DTIC Science & Technology

2017-05-25

relating to game theory and deception. This theory relates to a human phenomenon not strictly tied to any specific systems or actors at any level of war... game theory.10 It is worth emphasizing that reflexive control theory is neither synonymous with, nor did it evolve specifically from, maskirovka or... Game of ? And ?," edited by Chet Richards and Chuck Spinney (Defense and the National Interest, 2006). 19 Field Manual 6-0, Mission Command

Evolving Systems: An Outcome of Fondest Hopes and Wildest Dreams

NASA Technical Reports Server (NTRS)

Frost, Susan A.; Balas, Mark J.

2012-01-01

New theory is presented for evolving systems, which are autonomously controlled subsystems that self-assemble into a new evolved system with a higher purpose. Evolving systems of aerospace structures often require additional control when assembling to maintain stability during the entire evolution process. This is the concept of Adaptive Key Component Control that operates through one specific component to maintain stability during the evolution. In addition, this control must often overcome persistent disturbances that occur while the evolution is in progress. Theoretical results will be presented for Adaptive Key Component control for persistent disturbance rejection. An illustrative example will demonstrate the Adaptive Key Component controller on a system composed of rigid body and flexible body modes.

"Vygotsky's Neglected Legacy": Cultural-Historical Activity Theory

ERIC Educational Resources Information Center

Roth, Wolff-Michael; Lee, Yew-Jin

2007-01-01

The authors describe an evolving theoretical framework that has been called one of the best kept secrets of academia: cultural-historical activity theory, the result of proposals Lev Vygotsky first articulated but that his students and followers substantially developed to constitute much expanded forms in its second and third generations. Besides…

The interface theory of perception: the future of the science of the mind?

PubMed

Hickok, Gregory

2015-12-01

Perception is typically conceptualized as a neurocognitive system that evolved to reveal the truth about objects and events in the world. Hoffman et al.'s Interface Theory of Perception questions this assumption. If true, the implications for the science of the mind are profound.

The Progressive Development of Early Embodied Algebraic Thinking

ERIC Educational Resources Information Center

Radford, Luis

2014-01-01

In this article I present some results from a 5-year longitudinal investigation with young students about the genesis of embodied, non-symbolic algebraic thinking and its progressive transition to culturally evolved forms of symbolic thinking. The investigation draws on a cultural-historical theory of teaching and learning--the theory of…

Teaching Pragmatic Psychodynamic Psychotherapy to Graduate Social Work Students

ERIC Educational Resources Information Center

Duncan-Daston, Rana; Schneller, Debora

2016-01-01

Evolving developments in psychodynamic theory have strengthened it as an evidence-based approach and have made it concordant with social work's strengths-based, multicultural perspective. An elective focused on teaching fundamental concepts of psychodynamic psychotherapy was developed for graduate social work students based on Kolb's theory of…

Why E-Business Must Evolve beyond Market Orientation: Applying Human Interaction Models to Computer-Mediated Corporate Communications.

ERIC Educational Resources Information Center

Johnston, Kevin McCullough

2001-01-01

Considers the design of corporate communications for electronic business and discusses the increasing importance of corporate interaction as companies work in virtual environments. Compares sociological and psychological theories of human interaction and relationship formation with organizational interaction theories of corporate relationship…

A Theory of the Origin of the State

ERIC Educational Resources Information Center

Carneiro, Robert L.

1970-01-01

Suggests that states evolve in response to ecological or social circumscription, or resource concentration. When dense populations develop, fighting over land forces loser into political subordination or incorporation. This modification of coercive theories explain lack of state in Amazon basin and origin of Inca, Maya, Hwang Valley states.…

An Autoethnography of Masculinities: Flexibility and Flexing in Guyland

ERIC Educational Resources Information Center

Sweet, Joseph D.

2017-01-01

This autoethnography traces the author's shifting masculine identities as they have evolved across time and contexts. This piece splices journals and blogs from the author's past with prevailing masculinities theory, spectral data (Nordstrom, 2013), post-structural feminist theory and the author's present gender identity to investigate what can be…

Using Diffusion of Innovation Theory to Promote Universally Designed College Instruction

ERIC Educational Resources Information Center

Scott, Sally; McGuire, Joan

2017-01-01

Universal Design applied to college instruction has evolved and rapidly spread on an international scale. Diffusion of Innovation theory is described and used to identify patterns of change in this trend. Implications and strategies are discussed for promoting this inclusive approach to teaching in higher education.

Accounting for Cheating: An Evolving Theory and Emergent Themes

ERIC Educational Resources Information Center

Brent, Edward; Atkisson, Curtis

2011-01-01

This study examines student responses to the question, "What circumstances, if any, could make cheating justified?" It then assesses how well those responses can be classified by existing theories and categories that emerge from a qualitative analysis of the data. Results show considerable support for techniques of neutralization, partial support…

Children's Understanding of Morals.

ERIC Educational Resources Information Center

Lee, Lee C.

Research efforts in the area of moral development of the child, as based on Piaget's theory, are discussed. Some of the important processes Piaget uses to explain cognitive growth are presented first, followed by his theory of how the individual's capacity for moral judgment evolves. The research discussed tests Piaget's chief underlying…

The use of information theory in evolutionary biology.

PubMed

Adami, Christoph

2012-05-01

Information is a key concept in evolutionary biology. Information stored in a biological organism's genome is used to generate the organism and to maintain and control it. Information is also that which evolves. When a population adapts to a local environment, information about this environment is fixed in a representative genome. However, when an environment changes, information can be lost. At the same time, information is processed by animal brains to survive in complex environments, and the capacity for information processing also evolves. Here, I review applications of information theory to the evolution of proteins and to the evolution of information processing in simulated agents that adapt to perform a complex task. © 2012 New York Academy of Sciences.

Leadership, followership, and evolution: some lessons from the past.

PubMed

Van Vugt, Mark; Hogan, Robert; Kaiser, Robert B

2008-04-01

This article analyzes the topic of leadership from an evolutionary perspective and proposes three conclusions that are not part of mainstream theory. First, leading and following are strategies that evolved for solving social coordination problems in ancestral environments, including in particular the problems of group movement, intragroup peacekeeping, and intergroup competition. Second, the relationship between leaders and followers is inherently ambivalent because of the potential for exploitation of followers by leaders. Third, modern organizational structures are sometimes inconsistent with aspects of our evolved leadership psychology, which might explain the alienation and frustration of many citizens and employees. The authors draw several implications of this evolutionary analysis for leadership theory, research, and practice.

Game theory: applications for surgeons and the operating room environment.

PubMed

McFadden, David W; Tsai, Mitchell; Kadry, Bassam; Souba, Wiley W

2012-11-01

Game theory is an economic system of strategic behavior, often referred to as the "theory of social situations." Very little has been written in the medical literature about game theory or its applications, yet the practice of surgery and the operating room environment clearly involves multiple social situations with both cooperative and non-cooperative behaviors. A comprehensive review was performed of the medical literature on game theory and its medical applications. Definitive resources on the subject were also examined and applied to surgery and the operating room whenever possible. Applications of game theory and its proposed dilemmas abound in the practicing surgeon's world, especially in the operating room environment. The surgeon with a basic understanding of game theory principles is better prepared for understanding and navigating the complex Operating Room system and optimizing cooperative behaviors for the benefit all stakeholders. Copyright © 2012 Mosby, Inc. All rights reserved.

Center for Interface Science and Catalysis | Theory

Science.gov Websites

& Stanford School of Engineering Toggle navigation Home Research Publications People About Academic to overcome challenges associated with the atomic-scale design of catalysts for chemical computational methods we are developing a quantitative description of chemical processes at the solid-gas and

Faith-Based Human Services Initiatives: Considerations for Social Work Practice and Theory

ERIC Educational Resources Information Center

Tangenberg, Kathleen M.

2005-01-01

Faith-based human services initiatives present numerous challenges to professional social work. This article explores ways a theoretical integration of ecosystems and structuration perspectives may help social workers navigate complex ideological and practical implications of changing service delivery policies. The article highlights diversity…

Conducting Indigenous Research in Western Knowledge Spaces: Aligning Theory and Methodology

ERIC Educational Resources Information Center

Singh, Myra; Major, Jae

2017-01-01

Walking simultaneously in two worlds as an Indigenous researcher, navigating Indigenous and Western epistemologies/methodologies can have its challenges. Indigenous methodologies have become an important element of qualitative research and have been increasingly taken up by both Indigenous and non-Indigenous researchers. Indigenous methodologies…

Academic and Career Development: Rethinking Advising for Asian American Students

ERIC Educational Resources Information Center

Kodama, Corinne M.; Huynh, Jill

2017-01-01

Academic and career development for Asian American students is complicated by cultural influences, interdependence with family, and racial stereotyping. This chapter highlights research, theory, and practice to help educators rethink traditional advising approaches to more appropriately work with Asian American students as they navigate their…

Toward a Theory of Personal Politics

ERIC Educational Resources Information Center

Fritsch, Jocelyn

2010-01-01

The ability to effectively navigate organizational politics to achieve one's goals has long been recognized as necessary for individuals to experience success within their organizations. Many studies have linked the effective use of political behaviors to increased individual performance. As such, many scholars within HRD and other disciplines…

Evolution and Reengineering of NASA's Flight Dynamics Facility (FDF)

NASA Technical Reports Server (NTRS)

Stengle, Thomas; Hoge, Susan

2008-01-01

The NASA Goddard Space Flight Center's Flight Dynamics Facility (FDF) is a multimission support facility that performs ground navigation and spacecraft trajectory design services for a wide range of scientific satellites. The FDF also supports the NASA Space Network by providing orbit determination and tracking data evaluation services for the Tracking Data Relay Satellite System (TDRSS). The FDF traces its history to early NASA missions in the 1960's, including navigation support to the Apollo lunar missions. Over its 40 year history, the FDF has undergone many changes in its architecture, services offered, missions supported, management approach, and business operation. As a fully reimbursable facility (users now pay 100% of all costs for FDF operations and sustaining engineering activities), the FDF has faced significant challenges in recent years in providing mission critical products and services at minimal cost while defining and implementing upgrades necessary to meet future mission demands. This paper traces the history of the FDF and discusses significant events in the past that impacted the FDF infrastructure and/or business model, and the events today that are shaping the plans for the FDF in the next decade. Today's drivers for change include new mission requirements, the availability of new technology for spacecraft navigation, and continued pressures for cost reduction from FDF users. Recently, the FDF completed an architecture study based on these drivers that defines significant changes planned for the facility. This paper discusses the results of this study and a proposed implementation plan. As a case study in how flight dynamics operations have evolved and will continue to evolve, this paper focuses on two periods of time (1992 and the present) in order to contrast the dramatic changes that have taken place in the FDF. This paper offers observations and plans for the evolution of the FDF over the next ten years. Finally, this paper defines the mission model of the future for the FDF based on NASA's current mission list and planning for the Constellation Program. As part of this discussion the following are addressed: the relevance and benefits of a multi-mission facility for NASA's navigation operations in the future; anticipated technologies affecting ground orbit determination; continued incorporation of Commercial Off-the-shelf (COTS) software into the FDF; challenges of a business model that relies entirely on user fees to fund facility upgrades; anticipated changes in flight dynamics services required; and considerations for defining architecture upgrades given a set of cost drivers.

Theories of autism.

PubMed

Levy, Florence

2007-11-01

The purpose of the present paper was to review psychological theories of autism, and to integrate these theories with neurobiological findings. Cognitive, theory of mind, language and coherence theories were identified, and briefly reviewed. Psychological theories were found not to account for the rigid/repetitive behaviours universally described in autistic subjects, and underlying neurobiological systems were identified. When the developing brain encounters constrained connectivity, it evolves an abnormal organization, the features of which may be best explained by a developmental failure of neural connectivity, where high local connectivity develops in tandem with low long-range connectivity, resulting in constricted repetitive behaviours.

MAVEN-SA: Model-Based Automated Visualization for Enhanced Situation Awareness

DTIC Science & Technology

2005-11-01

34 methods. But historically, as arts evolve, these how to methods become systematized and codified (e.g. the development and refinement of color theory ...schema (as necessary) 3. Draw inferences from new knowledge to support decision making process 33 Visual language theory suggests that humans process...informed by theories of learning. Over the years, many types of software have been developed to support student learning. The various types of

Exact and approximate many-body dynamics with stochastic one-body density matrix evolution

NASA Astrophysics Data System (ADS)

Lacroix, Denis

2005-06-01

We show that the dynamics of interacting fermions can be exactly replaced by a quantum jump theory in the many-body density matrix space. In this theory, jumps occur between densities formed of pairs of Slater determinants, Dab=|Φa><Φb|, where each state evolves according to the stochastic Schrödinger equation given by O. Juillet and Ph. Chomaz [Phys. Rev. Lett. 88, 142503 (2002)]. A stochastic Liouville-von Neumann equation is derived as well as the associated. Bogolyubov-Born-Green-Kirwood-Yvon hierarchy. Due to the specific form of the many-body density along the path, the presented theory is equivalent to a stochastic theory in one-body density matrix space, in which each density matrix evolves according to its own mean-field augmented by a one-body noise. Guided by the exact reformulation, a stochastic mean-field dynamics valid in the weak coupling approximation is proposed. This theory leads to an approximate treatment of two-body effects similar to the extended time-dependent Hartree-Fock scheme. In this stochastic mean-field dynamics, statistical mixing can be directly considered and jumps occur on a coarse-grained time scale. Accordingly, numerical effort is expected to be significantly reduced for applications.

Honing Theory: A Complex Systems Framework for Creativity.

PubMed

Gabora, Liane

2017-01-01

This paper proposes a theory of creativity, referred to as honing theory, which posits that creativity fuels the process by which culture evolves through communal exchange amongst minds that are self-organizing, self-maintaining, and self-reproducing. According to honing theory, minds, like other self-organizing systems, modify their contents and adapt to their environments to minimize entropy. Creativity begins with detection of high psychological entropy material, which provokes uncertainty and is arousal-inducing. The creative process involves recursively considering this material from new contexts until it is sufficiently restructured that arousal dissipates. Restructuring involves neural synchrony and dynamic binding, and may be facilitated by temporarily shifting to a more associative mode of thought. A creative work may similarly induce restructuring in others, and thereby contribute to the cultural evolution of more nuanced worldviews. Since lines of cultural descent connecting creative outputs may exhibit little continuity, it is proposed that cultural evolution occurs at the level of self-organizing minds; outputs reflect their evolutionary state. Honing theory addresses challenges not addressed by other theories of creativity, such as the factors that guide restructuring, and in what sense creative works evolve. Evidence comes from empirical studies, an agent-based computational model of cultural evolution, and a model of concept combination.

Correlations and analytical approaches to co-evolving voter models

NASA Astrophysics Data System (ADS)

Ji, M.; Xu, C.; Choi, C. W.; Hui, P. M.

2013-11-01

The difficulty in formulating analytical treatments in co-evolving networks is studied in light of the Vazquez-Eguíluz-San Miguel voter model (VM) and a modified VM (MVM) that introduces a random mutation of the opinion as a noise in the VM. The density of active links, which are links that connect the nodes of opposite opinions, is shown to be highly sensitive to both the degree k of a node and the active links n among the neighbors of a node. We test the validity in the formalism of analytical approaches and show explicitly that the assumptions behind the commonly used homogeneous pair approximation scheme in formulating a mean-field theory are the source of the theory's failure due to the strong correlations between k, n and n2. An improved approach that incorporates spatial correlation to the nearest-neighbors explicitly and a random approximation for the next-nearest neighbors is formulated for the VM and the MVM, and it gives better agreement with the simulation results. We introduce an empirical approach that quantifies the correlations more accurately and gives results in good agreement with the simulation results. The work clarifies why simply mean-field theory fails and sheds light on how to analyze the correlations in the dynamic equations that are often generated in co-evolving processes.

Mechanisms of Oxidative Stress Resistance in The Brain: Lessons Learned From Hypoxia Tolerant Extremophilic Vertebrates

PubMed Central

Garbarino, Valentina R.; Orr, Miranda E.; Rodriguez, Karl A.; Buffenstein, Rochelle

2016-01-01

The Oxidative Stress Theory of Aging has had tremendous impact in research involving aging and age-associated diseases including those that affect the nervous system. With over half a century of accrued data showing both strong support for and against this theory, there is a need to critically evaluate the data acquired from common biomedical research models, and to also diversify the species used in studies involving this proximate theory. One approach is to follow Orgel’s second axiom that “evolution is smarter than we are” and judiciously choose species that may have evolved to live with chronic or seasonal oxidative stressors. Vertebrates that have naturally evolved to live under extreme conditions (e.g., anoxia or hypoxia), as well as those that undergo daily or seasonal torpor encounter both decreased oxygen availability and subsequent reoxygenation, with concomitant increased oxidative stress. Due to its high metabolic activity, the brain may be particularly vulnerable to oxidative stress. Here, we focus on oxidative stress responses in the brains of certain mouse models as well as extremophilic vertebrates. Exploring the naturally evolved biological tools utilized to cope with seasonal or environmentally variable oxygen availability may yield key information pertinent for how to deal with oxidative stress and thereby mitigate its propagation of age-associated diseases. PMID:25841340

On the trail of Vikings with polarized skylight: experimental study of the atmospheric optical prerequisites allowing polarimetric navigation by Viking seafarers.

PubMed

Horváth, Gábor; Barta, András; Pomozi, István; Suhai, Bence; Hegedüs, Ramón; Akesson, Susanne; Meyer-Rochow, Benno; Wehner, Rüdiger

2011-03-12

Between AD 900 and AD 1200 Vikings, being able to navigate skillfully across the open sea, were the dominant seafarers of the North Atlantic. When the Sun was shining, geographical north could be determined with a special sundial. However, how the Vikings could have navigated in cloudy or foggy situations, when the Sun's disc was unusable, is still not fully known. A hypothesis was formulated in 1967, which suggested that under foggy or cloudy conditions, Vikings might have been able to determine the azimuth direction of the Sun with the help of skylight polarization, just like some insects. This hypothesis has been widely accepted and is regularly cited by researchers, even though an experimental basis, so far, has not been forthcoming. According to this theory, the Vikings could have determined the direction of the skylight polarization with the help of an enigmatic birefringent crystal, functioning as a linearly polarizing filter. Such a crystal is referred to as 'sunstone' in one of the Viking's sagas, but its exact nature is unknown. Although accepted by many, the hypothesis of polarimetric navigation by Vikings also has numerous sceptics. In this paper, we summarize the results of our own celestial polarization measurements and psychophysical laboratory experiments, in which we studied the atmospheric optical prerequisites of possible sky-polarimetric navigation in Tunisia, Finland, Hungary and the high Arctic.

On the trail of Vikings with polarized skylight: experimental study of the atmospheric optical prerequisites allowing polarimetric navigation by Viking seafarers

PubMed Central

Horváth, Gábor; Barta, András; Pomozi, István; Suhai, Bence; Hegedüs, Ramón; Åkesson, Susanne; Meyer-Rochow, Benno; Wehner, Rüdiger

2011-01-01

Between AD 900 and AD 1200 Vikings, being able to navigate skillfully across the open sea, were the dominant seafarers of the North Atlantic. When the Sun was shining, geographical north could be determined with a special sundial. However, how the Vikings could have navigated in cloudy or foggy situations, when the Sun's disc was unusable, is still not fully known. A hypothesis was formulated in 1967, which suggested that under foggy or cloudy conditions, Vikings might have been able to determine the azimuth direction of the Sun with the help of skylight polarization, just like some insects. This hypothesis has been widely accepted and is regularly cited by researchers, even though an experimental basis, so far, has not been forthcoming. According to this theory, the Vikings could have determined the direction of the skylight polarization with the help of an enigmatic birefringent crystal, functioning as a linearly polarizing filter. Such a crystal is referred to as ‘sunstone’ in one of the Viking's sagas, but its exact nature is unknown. Although accepted by many, the hypothesis of polarimetric navigation by Vikings also has numerous sceptics. In this paper, we summarize the results of our own celestial polarization measurements and psychophysical laboratory experiments, in which we studied the atmospheric optical prerequisites of possible sky-polarimetric navigation in Tunisia, Finland, Hungary and the high Arctic. PMID:21282181

Psychophysical study of the visual sun location in pictures of cloudy and twilight skies inspired by Viking navigation.

PubMed

Barta, András; Horváth, Gábor; Meyer-Rochow, Victor Benno

2005-06-01

In the late 1960s it was hypothesized that Vikings had been able to navigate the open seas, even when the sun was occluded by clouds or below the sea horizon, by using the angle of polarization of skylight. To detect the direction of skylight polarization, they were thought to have made use of birefringent crystals, called "sun-stones," and a large part of the scientific community still firmly believe that Vikings were capable of polarimetric navigation. However, there are some critics who treat the usefulness of skylight polarization for orientation under partly cloudy or twilight conditions with extreme skepticism. One of their counterarguments has been the assumption that solar positions or solar azimuth directions could be estimated quite accurately by the naked eye, even if the sun was behind clouds or below the sea horizon. Thus under partly cloudy or twilight conditions there might have been no serious need for a polarimetric method to determine the position of the sun. The aim of our study was to test quantitatively the validity of this qualitative counterargument. In our psychophysical laboratory experiments, test subjects were confronted with numerous 180 degrees field-of-view color photographs of partly cloudy skies with the sun occluded by clouds or of twilight skies with the sun below the horizon. The task of the subjects was to guess the position or the azimuth direction of the invisible sun with the naked eye. We calculated means and standard deviations of the estimated solar positions and azimuth angles to characterize the accuracy of the visual sun location. Our data do not support the common belief that the invisible sun can be located quite accurately from the celestial brightness and/or color patterns under cloudy or twilight conditions. Although our results underestimate the accuracy of visual sun location by experienced Viking navigators, the mentioned counterargument cannot be taken seriously as a valid criticism of the theory of the alleged polarimetric Viking navigation. Our results, however, do not bear on the polarimetric theory itself.

Psychophysical study of the visual sun location in pictures of cloudy and twilight skies inspired by Viking navigation

NASA Astrophysics Data System (ADS)

Barta, András; Horváth, Gábor; Benno Meyer-Rochow, Victor

2005-06-01

In the late 1960s it was hypothesized that Vikings had been able to navigate the open seas, even when the sun was occluded by clouds or below the sea horizon, by using the angle of polarization of skylight. To detect the direction of skylight polarization, they were thought to have made use of birefringent crystals, called "sunstones," and a large part of the scientific community still firmly believe that Vikings were capable of polarimetric navigation. However, there are some critics who treat the usefulness of skylight polarization for orientation under partly cloudy or twilight conditions with extreme skepticism. One of their counterarguments has been the assumption that solar positions or solar azimuth directions could be estimated quite accurately by the naked eye, even if the sun was behind clouds or below the sea horizon. Thus under partly cloudy or twilight conditions there might have been no serious need for a polarimetric method to determine the position of the sun. The aim of our study was to test quantitatively the validity of this qualitative counterargument. In our psychophysical laboratory experiments, test subjects were confronted with numerous 180° field-of-view color photographs of partly cloudy skies with the sun occluded by clouds or of twilight skies with the sun below the horizon. The task of the subjects was to guess the position or the azimuth direction of the invisible sun with the naked eye. We calculated means and standard deviations of the estimated solar positions and azimuth angles to characterize the accuracy of the visual sun location. Our data do not support the common belief that the invisible sun can be located quite accurately from the celestial brightness and/or color patterns under cloudy or twilight conditions. Although our results underestimate the accuracy of visual sun location by experienced Viking navigators, the mentioned counterargument cannot be taken seriously as a valid criticism of the theory of the alleged polarimetric Viking navigation. Our results, however, do not bear on the polarimetric theory itself.

Mediating Factors in Literacy Instruction: How Novice Elementary Teachers Navigate New Teaching Contexts

ERIC Educational Resources Information Center

Scales, Roya Qualls; Wolsey, Thomas DeVere; Young, Janet; Smetana, Linda; Grisham, Dana L.; Lenski, Susan; Dobler, Elizabeth; Yoder, Karen Kreider; Chambers, Sandra A.

2017-01-01

This longitudinal study, framed by activity theory, examines what seven novice teachers' talk and actions reveal about their literacy teaching practices then delves into mediating influences of the teaching context. Utilizing collective, multi-case methods, data sources included interviews, observations, and artifacts. Findings indicate novices…

Theory, Guidance, and Flight Control for High Maneuverability Projectiles

DTIC Science & Technology

2014-01-01

estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining...2.8 Linear System Modeling with Time Delay ...................................................................22 2.9 Linear System Modeling Without... Time Delay .............................................................23 3. Guidance and Flight Control 24 3.1 Proportional Navigation Guidance Law

The Road to Culturally Relevant Science: Exploring How Teachers Navigate Change in Pedagogy

ERIC Educational Resources Information Center

Johnson, Carla C.

2011-01-01

In this study, two middle-school teachers who participated in a professional development program utilizing the transformative professional development (TPD) model are followed as they embarked upon becoming culturally relevant science teachers of Hispanic students. Using Ladson-Billings (1994) theory of culturally relevant pedagogy, teacher…

Towards an Understanding of Muslim American Adolescent High School Experiences

ERIC Educational Resources Information Center

Seward, Derek X.; Khan, Shaza

2016-01-01

The researchers conducted a grounded theory study to explore the experiences of Muslim American adolescents in high school. Findings indicate that students had to navigate unique challenges because of their religious faith, but those obstacles presented opportunities to confront bias and discrimination. Recommendations for how school counselors…

Emotions and Positional Identity in Becoming a Social Justice Science Teacher: Nicole's Story

ERIC Educational Resources Information Center

Rivera Maulucci, Maria S.

2013-01-01

Becoming a social justice teacher, for high-poverty urban settings, is fraught with emotional ambivalence related to personal, professional, relational, political, and cultural social justice issues. Prospective teachers must navigate their sense of justice, grapple with issues of educational disparity, engage with theories of critical,…

Mexican American Women Pursuing Counselor Education Doctorates: A Narrative Inquiry

ERIC Educational Resources Information Center

Hinojosa, Tamara J.; Carney, JoLynn V.

2016-01-01

The authors used narrative inquiry and Anzaldúa's (1999) bordlerlands theory to understand the cultural experiences of 5 Mexican American women in doctoral programs accredited by the Council for Accreditation of Counseling and Related Educational Programs. Results indicated that participants navigated multiple cultural spheres and that the…

Critical Thinking in Criminology: Critical Reflections on Learning and Teaching

ERIC Educational Resources Information Center

Howes, Loene M.

2017-01-01

Fostering critical thinking abilities amongst students is one component of preparing them to navigate uncertain and complex social lives and employment circumstances. One conceptualisation of critical thinking, valuable in higher education, draws from critical theory to promote social justice and redress power inequities. This study explored how…

A Mindfulness Experiential Small Group to Help Students Tolerate Ambiguity

ERIC Educational Resources Information Center

Bohecker, Lynn; Vereen, Linwood G.; Wells, Pamela C.; Wathen, Cristen C.

2016-01-01

This study explored the lived experiences of 20 counselors-in-training (CITs) in a mindfulness experiential small group. Using grounded theory, the authors described a 5-dimensional model for navigating ambiguity. Findings suggest mindfulness training provides CITs self-reflection skills and a greater ability to manage cognitive complexity.

Marginality and Mattering: Urban Latino Male Undergraduates in Higher Education

ERIC Educational Resources Information Center

Huerta, Adrian H.; Fishman, Seth M.

2014-01-01

This qualitative study of first-generation, low-income urban Latino male college students considers their transition experience and success in various higher education institutions. Schlossberg's theory of mattering and marginality is used as a lens to explore how these students navigate the college environment and build relationships with campus…

Navigating a Sea of Ideas: Teacher and Students Negotiate a Course toward Mutual Relevance.

ERIC Educational Resources Information Center

Flick, Lawrence B.

1995-01-01

Uses theories of social cognition and verbal communication to analyze how an experienced fourth-grade teacher blends teaching skills in language arts and reading with hands-on science to stimulate classroom inquiry. Discusses implications for elementary science instruction. Contains 41 references. (Author/JRH)

Re-Conceptualizing the Organizing Circumstance of Learning

ERIC Educational Resources Information Center

Spear Ellinwood, Karen Courtenay

2011-01-01

This study explores the web-navigation practices of adult learners in higher education and re-conceptualizes the concept of the organizing circumstance of self-managed learning, originated by Spear and Mocker (1984). The theoretical framework draws on funds of knowledge theory from a cultural historical perspective and elaborates a Vygotskian…

Finding the way with a noisy brain.

PubMed

Cheung, Allen; Vickerstaff, Robert

2010-11-11

Successful navigation is fundamental to the survival of nearly every animal on earth, and achieved by nervous systems of vastly different sizes and characteristics. Yet surprisingly little is known of the detailed neural circuitry from any species which can accurately represent space for navigation. Path integration is one of the oldest and most ubiquitous navigation strategies in the animal kingdom. Despite a plethora of computational models, from equational to neural network form, there is currently no consensus, even in principle, of how this important phenomenon occurs neurally. Recently, all path integration models were examined according to a novel, unifying classification system. Here we combine this theoretical framework with recent insights from directed walk theory, and develop an intuitive yet mathematically rigorous proof that only one class of neural representation of space can tolerate noise during path integration. This result suggests many existing models of path integration are not biologically plausible due to their intolerance to noise. This surprising result imposes significant computational limitations on the neurobiological spatial representation of all successfully navigating animals, irrespective of species. Indeed, noise-tolerance may be an important functional constraint on the evolution of neuroarchitectural plans in the animal kingdom.

HERMIES-I: a mobile robot for navigation and manipulation experiments

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

Weisbin, C.R.; Barhen, J.; de Saussure, G.

1985-01-01

The purpose of this paper is to report the current status of investigations ongoing at the Center for Engineering Systems Advanced Research (CESAR) in the areas of navigation and manipulation in unstructured environments. The HERMIES-I mobile robot, a prototype of a series which contains many of the major features needed for remote work in hazardous environments is discussed. Initial experimental work at CESAR has begun in the area of navigation. It briefly reviews some of the ongoing research in autonomous navigation and describes initial research with HERMIES-I and associated graphic simulation. Since the HERMIES robots will generally be composed ofmore » a variety of asynchronously controlled hardware components (such as manipulator arms, digital image sensors, sonars, etc.) it seems appropriate to consider future development of the HERMIES brain as a hypercube ensemble machine with concurrent computation and associated message passing. The basic properties of such a hypercube architecture are presented. Decision-making under uncertainty eventually permeates all of our work. Following a survey of existing analytical approaches, it was decided that a stronger theoretical basis is required. As such, this paper presents the framework for a recently developed hybrid uncertainty theory. 21 refs., 2 figs.« less

Social Welfare, the Neo-Conservative Turn and Educational Opportunity

ERIC Educational Resources Information Center

Moses, Michele S.

2004-01-01

This essay examines the educational opportunities of people in poverty who receive social welfare assistance. The dominant political theory underlying social policy (including education policy) in the United States has evolved from 1960s and 1970s welfare liberalism into 1980s and 1990s style neo-conservatism -- a theory that embraces principles…

Servant Leadership and Constructive Development Theory: How Servant Leaders Make Meaning of Service

ERIC Educational Resources Information Center

Phipps, Kelly A.

2010-01-01

A connection between servant leadership and constructive developmental theory is proposed. A theoretical framework is offered that examines the subject and object relationship for servant leaders at progressive stages of meaning making, showing how the way leaders make meaning of service evolves with their constructive development. The framework…

How College Science Students Engage in Note-Taking Strategies

ERIC Educational Resources Information Center

Bonner, Janice M.; Holliday, William G.

2006-01-01

A composite theory of college science student note-taking strategies was derived from a periodic series of five interviews with 23 students and with other variables, including original and final versions of notes analyzed during a semester-long genetics course. This evolving composite theory was later compared with Van Meter, Yokoi, and Pressley's…

Queering Place: The Intersection of Feminist Body Theory and Australian Aboriginal Collaboration

ERIC Educational Resources Information Center

Somerville, Margaret

2016-01-01

In this article the author used an auto-ethnographic philosophical approach to construct a fragile history of the present. Margaret Somerville reports doing this through tracing key moments and movements of queering feminist poststructural theory and evolving a queering method of body/place writing through her embeddedness in Aboriginal stories.…

Winners, Losers, Insiders, and Outsiders: Comparing Hierometer and Sociometer Theories of Self-Regard

PubMed Central

Mahadevan, Nikhila; Gregg, Aiden P.; Sedikides, Constantine; de Waal-Andrews, Wendy G.

2016-01-01

What evolutionary function does self-regard serve? Hierometer theory, introduced here, provides one answer: it helps individuals navigate status hierarchies, which feature zero-sum contests that can be lost as well as won. In particular, self-regard tracks social status to regulate behavioral assertiveness, augmenting or diminishing it to optimize performance in such contests. Hierometer theory also offers a conceptual counterpoint that helps resolve ambiguities in sociometer theory, which offers a complementary account of self-regard’s evolutionary function. In two large-scale cross-sectional studies, we operationalized theoretically relevant variables at three distinct levels of analysis, namely, social (relations: status, inclusion), psychological (self-regard: self-esteem, narcissism), and behavioral (strategy: assertiveness, affiliativeness). Correlational and mediational analyses consistently supported hierometer theory, but offered only mixed support for sociometer theory, including when controlling for confounding constructs (anxiety, depression). We interpret our results in terms of a broader agency-communion framework. PMID:27065896

How to recognize the work of researchers in astronomy communication?

NASA Astrophysics Data System (ADS)

Russo, Pedro

2015-08-01

One of the most important current trends in astronomy communication has been “change”. The field of astronomy communication has rapidly evolved in just the past few years, as new techniques and technologies have been adopted. Research astronomy has also visibly changed, as automation of survey systems and the launch of new telescopes has produced a tsunami of big data sets. Today, scientists and communicators must work together to navigate the raging waters of this data flood as they strive to keep our tech-savvy society informed.This invited talk will be given by Rick Fienberg.

The 25th Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting

NASA Technical Reports Server (NTRS)

Sydnor, Richard L. (Editor)

1994-01-01

Papers in the following categories are presented: recent developments in rubidium, cesium, and hydrogen-based frequency standards, and in cryogenic and trapped-ion technology; international and transnational applications of precise time and time interval (PTTI) technology with emphasis on satellite laser tracking networks, GLONASS timing, intercomparison of national time scales and international telecommunication; applications of PTTI technology to the telecommunications, power distribution, platform positioning, and geophysical survey industries; application of PTTI technology to evolving military communications and navigation systems; and dissemination of precise time and frequency by means of GPS, GLONASS, MILSTAR, LORAN, and synchronous communications satellites.

Innovations in Delta Differential One-Way Range: from Viking to Mars Science Laboratory

NASA Technical Reports Server (NTRS)

Border, James S.

2009-01-01

The Deep Space Network has provided the capability for very-long-baseline interferometry measurements in support of spacecraft navigation since the late 1970s. Both system implementation and the importance of such measurements to flight projects have evolved significantly over the past three decades. Innovations introduced through research and development programs have led to much better performance. This paper provides an overview of the development and use of interferometric tracking techniques in the DSN starting with the Viking era and continuing with a description of the current system and its planned use to support Mars Science Laboratory.

USGS Water Data for Washington

USGS Publications Warehouse

,

2009-01-01

The U.S. Geological Survey (USGS) has been investigating the water resources of Washington State since the latter part of the 19th century. During this time, demand for water has evolved from primarily domestic and stock needs to the current complex requirements for public-water supplies, irrigation, power generation, navigation, ecological needs, and numerous other uses. Water-resource data collected by the USGS in Washington have been, or soon will be, published by the USGS Washington Water Science Center (WAWSC) in numerous data and interpretive reports. Most of these reports are available online at the WAWSC web page http://wa.water.usgs.gov/pubs/

How cancer shapes evolution, and how evolution shapes cancer

PubMed Central

Casás-Selves, Matias; DeGregori, James

2013-01-01

Evolutionary theories are critical for understanding cancer development at the level of species as well as at the level of cells and tissues, and for developing effective therapies. Animals have evolved potent tumor suppressive mechanisms to prevent cancer development. These mechanisms were initially necessary for the evolution of multi-cellular organisms, and became even more important as animals evolved large bodies and long lives. Indeed, the development and architecture of our tissues were evolutionarily constrained by the need to limit cancer. Cancer development within an individual is also an evolutionary process, which in many respects mirrors species evolution. Species evolve by mutation and selection acting on individuals in a population; tumors evolve by mutation and selection acting on cells in a tissue. The processes of mutation and selection are integral to the evolution of cancer at every step of multistage carcinogenesis, from tumor genesis to metastasis. Factors associated with cancer development, such as aging and carcinogens, have been shown to promote cancer evolution by impacting both mutation and selection processes. While there are therapies that can decimate a cancer cell population, unfortunately, cancers can also evolve resistance to these therapies, leading to the resurgence of treatment-refractory disease. Understanding cancer from an evolutionary perspective can allow us to appreciate better why cancers predominantly occur in the elderly, and why other conditions, from radiation exposure to smoking, are associated with increased cancers. Importantly, the application of evolutionary theory to cancer should engender new treatment strategies that could better control this dreaded disease. PMID:23705033

Developing a Taxonomy of Characteristics and Features of Learning Systems and Internet Gaming Environments

DTIC Science & Technology

2006-09-01

Learning methodologies have been developed over a number of years and it has evolved as technologies advance and new learning theories emerge. We...can be used to justify learning systems. Many theories are developed . We introduce significant learning theories in this section. 2.1 Behaviorism...not fitting well with traditional classroom environment. 3 2.3 Cognitivism Piaget believed that humans desire a state of cognitive balance or

Factor Analysis of Computer-Based Multidimensional Aptitude Battery-Second Edition Intelligence Testing from Rated U.S. Air Force Pilots

DTIC Science & Technology

2012-09-01

intelligence continues to evolve as attention to cognitive processes and mechanisms, a deeper understanding of related issues, and new theories ...hierarchical models that describe specific abilities arranged according to increasing specificity and developmental complexity [6-8]. Theories have also...persistence) not tapped directly by existing measures of intellectual ability. Wechsler’s theory of intelligence is central to the development of the mostly

On the theory of the type III burst exciter

NASA Technical Reports Server (NTRS)

Smith, R. A.; Goldstein, M. L.; Papadopoulos, K.

1976-01-01

In situ satellite observations of type III burst exciters at 1 AU show that the beam does not evolve into a plateau in velocity space, contrary to the prediction of quasilinear theory. The observations can be explained by a theory that includes mode coupling effects due to excitation of the parametric oscillating two-stream instability and its saturation by anomalous resistivity. The time evolution of the beam velocity distribution is included in the analysis.

Impacts of Colville River dynamics on river navigability near Nuiqsut, Alaska: 1955-present

NASA Astrophysics Data System (ADS)

Whitley, M. A.; Panda, S. K.; Prakash, A.; Brinkman, T. J.

2016-12-01

Climate-driven changes in river systems are challenging access to ecosystem services such as access to traditional hunting grounds and other subsistence food sources on the North Slope of Alaska. This work studies the dynamics of the Colville River and assesses the impacts on traditional harvest practices and subsistence travel of the Native community of Nuiqsut. Recent reports from Nuiqsut residents indicate accelerated changes in the environment, limiting river travel and their ability to harvest subsistence food. This study explores how channel migration, gravel bars, and bank erosion have evolved since the 1950s, and their impact on water depth and navigability. In an area of ice-rich permafrost, warmer summer temperatures exacerbate lateral bank erosion, resulting in river siltation. The study focuses on selected key areas south of Nuiqsut that have shown significant change in river geomorphology. Since 1955, some areas proximate to ice wedge exposures show channel migration in excess of 1 km. Panchromatic aerial photography acquired by US Geological Surveys in the mid 1950s, color infrared aerial photography from 1979 and 1982 acquired by the Alaska High Altitude Photography (AHAP) mission, and high resolution satellite images from Digital Globe, Inc. were used in this study. We mapped water, vegetation, and gravel/non-vegetated classes to identify risk areas for river navigability. River bathymetry was also mapped using a multispectral ratio-based water depth retrieval algorithm to identify problem sites for boat travel. Remote sensing products and analyses were validated with field data for mapping risk areas along the river. This study has the potential to be implemented on a larger scale for predictive mapping to aid river navigation. Findings from this study will provide insight whether recent changes are anomalies, or if they are part of a directional trend that will require local adaptation.

Quasispecies theory for evolution of modularity.

PubMed

Park, Jeong-Man; Niestemski, Liang Ren; Deem, Michael W

2015-01-01

Biological systems are modular, and this modularity evolves over time and in different environments. A number of observations have been made of increased modularity in biological systems under increased environmental pressure. We here develop a quasispecies theory for the dynamics of modularity in populations of these systems. We show how the steady-state fitness in a randomly changing environment can be computed. We derive a fluctuation dissipation relation for the rate of change of modularity and use it to derive a relationship between rate of environmental changes and rate of growth of modularity. We also find a principle of least action for the evolved modularity at steady state. Finally, we compare our predictions to simulations of protein evolution and find them to be consistent.

Curvature-Guided Motility of Microalgae in Geometric Confinement

NASA Astrophysics Data System (ADS)

Ostapenko, Tanya; Schwarzendahl, Fabian Jan; Böddeker, Thomas J.; Kreis, Christian Titus; Cammann, Jan; Mazza, Marco G.; Bäumchen, Oliver

2018-02-01

Microorganisms, such as bacteria and microalgae, often live in habitats consisting of a liquid phase and a plethora of interfaces. The precise ways in which these motile microbes behave in their confined environment remain unclear. Using experiments and Brownian dynamics simulations, we study the motility of a single Chlamydomonas microalga in an isolated microhabitat with controlled geometric properties. We demonstrate how the geometry of the habitat controls the cell's navigation in confinement. The probability of finding the cell swimming near the boundary increases with the wall curvature, as seen for both circular and elliptical chambers. The theory, utilizing an asymmetric dumbbell model of the cell and steric wall interactions, captures this curvature-guided navigation quantitatively with no free parameters.

How evolution learns to generalise: Using the principles of learning theory to understand the evolution of developmental organisation.

PubMed

Kouvaris, Kostas; Clune, Jeff; Kounios, Loizos; Brede, Markus; Watson, Richard A

2017-04-01

One of the most intriguing questions in evolution is how organisms exhibit suitable phenotypic variation to rapidly adapt in novel selective environments. Such variability is crucial for evolvability, but poorly understood. In particular, how can natural selection favour developmental organisations that facilitate adaptive evolution in previously unseen environments? Such a capacity suggests foresight that is incompatible with the short-sighted concept of natural selection. A potential resolution is provided by the idea that evolution may discover and exploit information not only about the particular phenotypes selected in the past, but their underlying structural regularities: new phenotypes, with the same underlying regularities, but novel particulars, may then be useful in new environments. If true, we still need to understand the conditions in which natural selection will discover such deep regularities rather than exploiting 'quick fixes' (i.e., fixes that provide adaptive phenotypes in the short term, but limit future evolvability). Here we argue that the ability of evolution to discover such regularities is formally analogous to learning principles, familiar in humans and machines, that enable generalisation from past experience. Conversely, natural selection that fails to enhance evolvability is directly analogous to the learning problem of over-fitting and the subsequent failure to generalise. We support the conclusion that evolving systems and learning systems are different instantiations of the same algorithmic principles by showing that existing results from the learning domain can be transferred to the evolution domain. Specifically, we show that conditions that alleviate over-fitting in learning systems successfully predict which biological conditions (e.g., environmental variation, regularity, noise or a pressure for developmental simplicity) enhance evolvability. This equivalence provides access to a well-developed theoretical framework from learning theory that enables a characterisation of the general conditions for the evolution of evolvability.

Cognitive Offloading Does Not Prevent but Rather Promotes Cognitive Development

PubMed Central

Nolfi, Stefano

2016-01-01

We investigate the relation between the development of reactive and cognitive capabilities. In particular we investigate whether the development of reactive capabilities prevents or promotes the development of cognitive capabilities in a population of evolving robots that have to solve a time-delay navigation task in a double T-Maze environment. Analysis of the experiments reveals that the evolving robots always select reactive strategies that rely on cognitive offloading, i.e., the possibility of acting so as to encode onto the relation between the agent and the environment the states that can be used later to regulate the agent’s behavior. The discovery of these strategies does not prevent, but rather facilitates, the development of cognitive strategies that also rely on the extraction and use of internal states. Detailed analysis of the results obtained in the different experimental conditions provides evidence that helps clarify why, contrary to expectations, reactive and cognitive strategies tend to have synergetic relationships. PMID:27505162

Evolved differences in larval social behavior mediated by novel pheromones

PubMed Central

Mast, Joshua D; De Moraes, Consuelo M; Alborn, Hans T; Lavis, Luke D; Stern, David L

2014-01-01

Pheromones, chemical signals that convey social information, mediate many insect social behaviors, including navigation and aggregation. Several studies have suggested that behavior during the immature larval stages of Drosophila development is influenced by pheromones, but none of these compounds or the pheromone-receptor neurons that sense them have been identified. Here we report a larval pheromone-signaling pathway. We found that larvae produce two novel long-chain fatty acids that are attractive to other larvae. We identified a single larval chemosensory neuron that detects these molecules. Two members of the pickpocket family of DEG/ENaC channel subunits (ppk23 and ppk29) are required to respond to these pheromones. This pheromone system is evolving quickly, since the larval exudates of D. simulans, the sister species of D. melanogaster, are not attractive to other larvae. Our results define a new pheromone signaling system in Drosophila that shares characteristics with pheromone systems in a wide diversity of insects. DOI: http://dx.doi.org/10.7554/eLife.04205.001 PMID:25497433

Using a complex adaptive system lens to understand family caregiving experiences navigating the stroke rehabilitation system.

PubMed

Ghazzawi, Andrea; Kuziemsky, Craig; O'Sullivan, Tracey

2016-10-01

Family caregivers provide the stroke survivor with social support and continuity during the transition home from a rehabilitation facility. In this exploratory study we examined family caregivers' perceptions and experiences navigating the stroke rehabilitation system. The theories of continuity of care and complex adaptive systems were integrated to examine the transition from a stroke rehabilitation facility to the patient's home. This study provides an understanding of the interacting complexities at the macro and micro levels. A convenient sample of family caregivers (n = 14) who provide care for a stroke survivor were recruited 4-12 weeks following the patient's discharge from a stroke rehabilitation facility in Ontario, Canada. Interviews were conducted with family caregivers to examine their perceptions and experiences navigating the stroke rehabilitation system. Directed and inductive content analysis and the theory of Complex Adaptive Systems were used to interpret the perceptions of family caregivers. Health system policies and procedures at the macro-level determined the types and timing of information being provided to caregivers, and impacted continuity of care and access to supports and services at the micro-level. Supports and services in the community, such as outpatient physiotherapy services, were limited or did not meet the specific needs of the stroke survivors or family caregivers. Relationships with health providers, informational support, and continuity in case management all influence the family caregiving experience and ultimately the quality of care for the stroke survivor, during the transition home from a rehabilitation facility.

Status and Perspective of the IGS Multi-GNSS Experiment (MGEX)

NASA Astrophysics Data System (ADS)

Steigenberger, Peter; Montenbruck, Oliver; Weber, Robert; Hugentobler, Urs

2013-04-01

Following three decades, during which the Global Positioning System GPS has evolved from a military navigation system into an indispensable tool for geodetic research and global monitoring of the Earth, the world of satellite navigation has experienced dramatic changes over the past years. With GLONASS, a second global navigation system has achieved a fully operational status, GPS is introducing modernized civil and encrypted navigation signals, and a variety of new navigation constellations are being built-up in Asia and Europe. These include BeiDou, which has recently opened a regional navigation service in the Asia-Pacific region, Galileo, which now has four satellites in orbit, as well as QZSS, which offers a unique set of signals and service features. In recognition of a rapidly changing GNSS landscape, the International GNSS Service (IGS) has initiated the Multi-GNSS Experiment (MGEX - http://igs.org/mgex) as a platform for early familiarization with emerging navigation systems and to pave the way for a full-featured use thereof in a future multi-GNSS service. As a first step, MGEX has promoted the build-up of a new global network of GNSS monitoring stations, each tracking at least one new constellation (Galileo, BeiDou, or QZSS) on top of GPS, GLONASS and SBAS. By the end of 2012, approximately 50 stations contribute offline and/or real-time data to the MGEX network. To facilitate introduction of new standards (specifically RINEX3 observation and navigation data formats), distinct data archives are used even for those MGEX stations jointly contributing to the legacy IGS. Building-up on the new multi-GNSS network, the generation of associated orbit and clock products has started in the second quarter of 2012. At this stage, only Galileo and QZSS products are offered by selected MGEX Analysis Centers, but the addition of BeiDou is expected in 2013 as the MGEX network expands and new Analysis Centers join the data processing effort. Despite remarkable progress in the first year of the MGEX project, numerous challenges have still to be met before the new constellations can contribute to high-grade navigation and geodetic services. So far, only an immature knowledge of the new navigation satellites and the transmitted signals is available. Much work is left to fully characterize the multitude of inter-signal, inter-frequency and inter-system biases, as well as antenna phase patterns in both the space and user segment. Likewise, proper knowledge of spacecraft attitude control and radiation pressure models appears indispensable for a proper generation of highly-accurate orbit and clock products. Only then will users be able to fully benefit from the high potential of robust, wide-band, and high navigation signals as well as new generations of highly stable clocks offered by the new constellations. Within the presentation, the MGEX project will be introduced and the latest achievements in the network build-up, the product generation and related activities will be presented. Current challenges and necessary steps towards a full-features multi-GNSS service of the IGS will be identified.

Nonlinearity analysis of measurement model for vision-based optical navigation system

NASA Astrophysics Data System (ADS)

Li, Jianguo; Cui, Hutao; Tian, Yang

2015-02-01

In the autonomous optical navigation system based on line-of-sight vector observation, nonlinearity of measurement model is highly correlated with the navigation performance. By quantitatively calculating the degree of nonlinearity of the focal plane model and the unit vector model, this paper focuses on determining which optical measurement model performs better. Firstly, measurement equations and measurement noise statistics of these two line-of-sight measurement models are established based on perspective projection co-linearity equation. Then the nonlinear effects of measurement model on the filter performance are analyzed within the framework of the Extended Kalman filter, also the degrees of nonlinearity of two measurement models are compared using the curvature measure theory from differential geometry. Finally, a simulation of star-tracker-based attitude determination is presented to confirm the superiority of the unit vector measurement model. Simulation results show that the magnitude of curvature nonlinearity measurement is consistent with the filter performance, and the unit vector measurement model yields higher estimation precision and faster convergence properties.

Optimization design about gimbal structure of high-precision autonomous celestial navigation tracking mirror system

NASA Astrophysics Data System (ADS)

Huang, Wei; Yang, Xiao-xu; Han, Jun-feng; Wei, Yu; Zhang, Jing; Xie, Mei-lin; Yue, Peng

2016-01-01

High precision tracking platform of celestial navigation with control mirror servo structure form, to solve the disadvantages of big volume and rotational inertia, slow response speed, and so on. It improved the stability and tracking accuracy of platform. Due to optical sensor and mirror are installed on the middle-gimbal, stiffness and resonant frequency requirement for high. Based on the application of finite element modality analysis theory, doing Research on dynamic characteristics of the middle-gimbal, and ANSYS was used for the finite element dynamic emulator analysis. According to the result of the computer to find out the weak links of the structure, and Put forward improvement suggestions and reanalysis. The lowest resonant frequency of optimization middle-gimbal avoid the bandwidth of the platform servo mechanism, and much higher than the disturbance frequency of carrier aircraft, and reduces mechanical resonance of the framework. Reaching provides a theoretical basis for the whole machine structure optimization design of high-precision of autonomous Celestial navigation tracking mirror system.

How do mice follow odor trails?

NASA Astrophysics Data System (ADS)

Zwicker, David; Trastour, Sophie; Mishra, Shruti; Mathis, Alexander; Murthy, Venkatesh; Brenner, Michael P.

2015-11-01

Mice are excellent at following odor trails e.g. to locate food or to find mates. However, it is not yet understood what navigation strategies they use. In principle, they could either evaluate temporal differences between sniffs or they could use concurrent input from the two nostrils. It is unknown to what extend these two strategies contribute to mice's performance. When mice follow trails, odors evaporate from the ground, are transported by flow in the air, and are then inhaled with the two nostrils. In order to differentiate between the two navigation strategies, we determine what information the mouse receives: first, we calculate the airflow by numerically solving the incompressible Navier-Stokes equations. We then determine the spatiotemporal odor concentration from the resulting advection-diffusion equations. Lastly, we determine the odor amount in each nostril by calculating the inhalation volumes using potential flow theory. Taken together, we determine the odor amount in each nostril during each sniff, allowing a detailed study of navigation strategies.

An extension of the coevolution theory of the origin of the genetic code

PubMed Central

Di Giulio, Massimo

2008-01-01

Background The coevolution theory of the origin of the genetic code suggests that the genetic code is an imprint of the biosynthetic relationships between amino acids. However, this theory does not seem to attribute a role to the biosynthetic relationships between the earliest amino acids that evolved along the pathways of energetic metabolism. As a result, the coevolution theory is unable to clearly define the very earliest phases of genetic code origin. In order to remove this difficulty, I here suggest an extension of the coevolution theory that attributes a crucial role to the first amino acids that evolved along these biosynthetic pathways and to their biosynthetic relationships, even when defined by the non-amino acid molecules that are their precursors. Results It is re-observed that the first amino acids to evolve along these biosynthetic pathways are predominantly those codified by codons of the type GNN, and this observation is found to be statistically significant. Furthermore, the close biosynthetic relationships between the sibling amino acids Ala-Ser, Ser-Gly, Asp-Glu, and Ala-Val are not random in the genetic code table and reinforce the hypothesis that the biosynthetic relationships between these six amino acids played a crucial role in defining the very earliest phases of genetic code origin. Conclusion All this leads to the hypothesis that there existed a code, GNS, reflecting the biosynthetic relationships between these six amino acids which, as it defines the very earliest phases of genetic code origin, removes the main difficulty of the coevolution theory. Furthermore, it is here discussed how this code might have naturally led to the code codifying only for the domains of the codons of precursor amino acids, as predicted by the coevolution theory. Finally, the hypothesis here suggested also removes other problems of the coevolution theory, such as the existence for certain pairs of amino acids with an unclear biosynthetic relationship between the precursor and product amino acids and the collocation of Ala between the amino acids Val and Leu belonging to the pyruvate biosynthetic family, which the coevolution theory considered as belonging to different biosyntheses. Reviewers This article was reviewed by Rob Knight, Paul Higgs (nominated by Laura Landweber), and Eugene Koonin. PMID:18775066

Relational-Cultural Theory: A Framework for Relational Competencies and Movement in Group Work with Female Adolescents

ERIC Educational Resources Information Center

Cannon, Kristi B.; Hammer, Tonya R.; Reicherzer, Stacee; Gilliam, Billie J.

2012-01-01

Relational-cultural theory (RCT) is an evolving feminist model of human development that places emphasis on growth-fostering relationships as building blocks for wellness. This article demonstrates the use of RCT in addressing relational aggression, including cyberbullying, in counseling a group of adolescent girls. The group counselor's…

Sheldon Glashow, the Electroweak Theory, and the Grand Unified Theory

Science.gov Websites

] 'Glashow shared the 1979 Nobel Prize for physics with Steven Weinberg and Abdus Salam for unifying the particle physics and provides a framework for understanding how the early universe evolved and how the our universe came into being," says Lawrence R. Sulak, chairman of the Boston University physics

The Role of Theory in the Assessment of Sex Offenders

ERIC Educational Resources Information Center

Quackenbush, Ray E.

2003-01-01

No generally accepted theory of sex offender behavior exists at this point. As clinical experience and research findings interact within an evolving theoretical framework, the picture of what is important, as well as what is possible to know about a sex offender, is rapidly changing. It is vital that mental health professionals, the legal system,…

System Models of Information, Communication and Mass Communication: Revaluation of Some Basic Concepts of Communication.

ERIC Educational Resources Information Center

Wiio, Osmo A.

A more unified approach to communication theory can evolve through systems modeling of information theory, communication modes, and mass media operations. Such systematic analysis proposes, as is the case care here, that information models be based upon combinations of energy changes and exchanges and changes in receiver systems. The mass media is…

Discourse of the Firetenders: Considering Contingent Faculty through the Lens of Activity Theory

ERIC Educational Resources Information Center

Doe, Sue; Barnes, Natalie; Bowen, David; Gilkey, David; Smoak, Ginger Guardiola; Ryan, Sarah; Sarell, Kirk; Thomas, Laura H.; Troup, Lucy J.; Palmquist, Mike

2011-01-01

In this article, the authors explore the multiple roles that contingent faculty play in an evolving system of higher education. They consider the professional work of faculty in contingent positions at Colorado State University through the lens of activity theory, analyzing workplace discourse logs in an effort to understand the roles of…

Career Counselling an African Immigrant Student in a USA School Setting: Merging Transition Theory with a Narrative Approach

ERIC Educational Resources Information Center

Mims, M. J.; Mims, G. A.; Newland, L. A.

2009-01-01

A global professional discourse has emerged among career specialists inviting a critical examination of conventional career theory and calling for innovative, postmodern approaches that capture the complex, unique and evolving needs of diverse and disadvantaged students. Using a narrative case study the authors evaluate and describe the…

Applying Contemporary Developmental and Movement Science Theories and Evidence to Early Intervention Practice

ERIC Educational Resources Information Center

Hickman, Robbin; McCoy, Sarah Westcott; Long, Toby M.; Rauh, Mitchell J.

2011-01-01

Changes in early childhood science, theory, and best practices for improving outcomes of children with motor delay or dysfunction and their families have evolved rapidly since EI began. Changes in daily early intervention (EI) practice have been more elusive. Closing the gap between knowledge and practice requires EI providers to piece together…

Spaceflight dynamics 1993; AAS/NASA International Symposium, 8th, Greenbelt, MD, Apr. 26-30, 1993, Parts 1 & 2

NASA Technical Reports Server (NTRS)

Teles, Jerome (Editor); Samii, Mina V. (Editor)

1993-01-01

A conference on spaceflight dynamics produced papers in the areas of orbit determination, spacecraft tracking, autonomous navigation, the Deep Space Program Science Experiment Mission (DSPSE), the Global Positioning System, attitude control, geostationary satellites, interplanetary missions and trajectories, applications of estimation theory, flight dynamics systems, low-Earth orbit missions, orbital mechanics, mission experience in attitude dynamics, mission experience in sensor studies, attitude dynamics theory and simulations, and orbit-related experience. These papaers covered NASA, European, Russian, Japanese, Chinese, and Brazilian space programs and hardware.

Is There a Geometric Module for Spatial Orientation? Insights from a Rodent Navigation Model

ERIC Educational Resources Information Center

Sheynikhovich, Denis; Chavarriaga, Ricardo; Strosslin, Thomas; Arleo, Angelo; Gerstner, Wulfram

2009-01-01

Modern psychological theories of spatial cognition postulate the existence of a geometric module for reorientation. This concept is derived from experimental data showing that in rectangular arenas with distinct landmarks in the corners, disoriented rats often make diagonal errors, suggesting their preference for the geometric (arena shape) over…

Dredged Material Placement Site Capacity Analysis for Navigation Improvement Project at Grays Harbor, WA

DTIC Science & Technology

2012-09-01

report are not to be used for advertising , publication, or promotional purposes. Citation of trade names does not constitute an official endorsement...nonlinear wave theories and solution methods may be used in wave transformation models for mono- chromatic and irregular or random waves moving from deep

Constructing a Voice in English as a Foreign Language: Identity and Engagement

ERIC Educational Resources Information Center

Nasrollahi Shahri, Mohammad Naseh

2018-01-01

Situated in an English as a foreign language (EFL) context, this study navigates the intersection of language learner identity and foreign language engagement. Specifically, drawing on the concept of voice (Canagarajah, 2013; Johnstone, 1996; Kramsch, 2003), Bakhtin's (1981) theory of language, and the notion of investment (Darvin & Norton,…

Navigating a Literacy Landscape: Teaching Conceptual Understanding with Multiple Text Types

ERIC Educational Resources Information Center

Boyd, Fenice B.; Ikpeze, Chinwe H.

2007-01-01

The authors draw on Cognitive Flexibility Theory (Spiro, Coulson, Feltovich, & Anderson, 2004) as a lens to examine one seventh-grade English language arts teacher's pedagogical approach to using multiple text types to develop students' conceptual understandings about the 1957 integration of Little Rock's Central High School. Multiple text types…

Future Directions: An Alternate Organizational Lens on Middle-of-the-Road Education Reforms

ERIC Educational Resources Information Center

Mercado-Garcia, Diana

2017-01-01

This essay response critically examines and expands on the arguments put forth by the authors of "Navigating Middle-of-the-Road Reforms through Collaborative Community." Using organizational theory, the paper clarifies questions about the theoretical construct of collaborative community and middle-of-the-road reforms. It concludes by…

"Why Should I Be like Bloody Rain Man?!" Navigating the Autistic Identity

ERIC Educational Resources Information Center

MacLeod, Andrea; Lewis, Ann; Robertson, Christopher

2013-01-01

This article explores the views of six higher education students with autism/Asperger syndrome. The research draws upon social identity theory to explore how participants made meaning of their label. There was consensus that information given at the point of diagnosis generally did not reflect their individual experiences. First-hand accounts…

Navigating the Turbulent Waters of School Reform Guided by Complexity Theory

ERIC Educational Resources Information Center

White, David G.; Levin, James A.

2016-01-01

The goal of this research study has been to develop, implement, and evaluate a school reform design experiment at a continuation high school with low-income, low-performing underrepresented minority students. The complexity sciences served as a theoretical framework for this design experiment. Treating an innovative college preparatory program as…

Navigating Contradictory Communities of Practice in Learning to Teach for Social Justice

ERIC Educational Resources Information Center

Flores, Maria Timmons

2007-01-01

In this article, I explore the contradictions that four new teachers experienced as their commitments to social justice collide with urban school culture. Framed within Jean Lave and Etienne Wenger's (1999) theory of situated learning and development concepts of identity, practice, and relationships illustrate how teachers' ideals are challenged…

Bridging Borders: Toward a Pedagogy of Preparedness for Visiting Faculty

ERIC Educational Resources Information Center

Mizzi, Robert C.

2017-01-01

This analytical article largely draws on the experiences of visiting faculty teaching at post-secondary institutions overseas. What is largely understood in the literature is that visiting faculty need to navigate the sociocultural, professional, and contextual differences that shape the work context. Drawing on the theory of border pedagogy, this…

Navigating Tensions between Conceptual and Metaconceptual Goals in the Use of Models

ERIC Educational Resources Information Center

Delgado, Cesar

2015-01-01

Science education involves learning about phenomena at three levels: concrete (facts and generalizations), conceptual (concepts and theories), and metaconceptual (epistemology) (Snir et al. in "J Sci Educ Technol" 2(2):373-388, 1993). Models are key components in science, can help build conceptual understanding, and may also build…

Ethical Fairy Tales: Using Fairy Tales as Illustrative Ethical Dilemmas with Counseling Students

ERIC Educational Resources Information Center

Henderson, Kathryn L.; Malone, Stefanie L.

2012-01-01

Learning to navigate ethical dilemmas is important in counseling students' training. According to the Council for the Accreditation of Counseling and Related Educational Programs (2009 standards, counseling students must receive ethics education. A common goal for counselor educators is to assist students in translating ethical theory into…

Black Educators Fight Back: Facing and Navigating Vulnerability and Stress in Teacher Development

ERIC Educational Resources Information Center

Gist, Conra D.

2018-01-01

This article examines Black educators' experiences in Grow Your Own programs along a teacher development continuum at the intersection of social and human development constructs and frameworks, such as double binds and Phenomenological Variant Ecological Systems Theory (PVEST). More robust and nuanced interpretations of how Black educators grow…

Risk, Protection, and Achievement Disparities among African American Males: Cross-Generation Theory, Research, and Comprehensive Intervention

ERIC Educational Resources Information Center

Rowley, Larry L.; Bowman, Phillip J.

2009-01-01

In this post-industrial global society, parental and student role strains may exacerbate social-ecological risks and academic difficulties of African American male students. Therefore, school-based interventions must ensure rigorous preparation, promote successful navigation of social-ecological risks, and mobilize cultural-ecological strengths to…

"No One Taught Me the Steps": Latinos' Experiences Applying to Graduate School

ERIC Educational Resources Information Center

Ramirez, Elvia

2011-01-01

Based on in-depth qualitative interviews, this study examined Latinos' graduate school choice process. Grounded in intersectionality and social and cultural capital theories, this study examined barriers and support structures encountered by Latinos as they navigate through the graduate school application phase. Findings reveal that lack of access…

Working Memory for Patterned Sequences of Auditory Objects in a Songbird

ERIC Educational Resources Information Center

Comins, Jordan A.; Gentner, Timothy Q.

2010-01-01

The capacity to remember sequences is critical to many behaviors, such as navigation and communication. Adult humans readily recall the serial order of auditory items, and this ability is commonly understood to support, in part, the speech processing for language comprehension. Theories of short-term serial recall posit either use of absolute…

Schooling in Capitalism: Navigating the Bleak Pathways of Structural Fate

ERIC Educational Resources Information Center

Murray, Kevin; Liston, Daniel P.

2015-01-01

In this review essay Kevin Murray and Dan Liston examine three texts in what this symposium has deemed the recent resurgence in neo-Marxist accounts of schooling: David Blacker's "The Falling Rate of Learning and the Neoliberal Endgame," Mike Cole's "Marxism and Educational Theory," and John Marsh's "Class Dismissed."…

Making Meaning of Experience: Navigating the Transformation from Graduate Student to Tenure-Track Professor

ERIC Educational Resources Information Center

Coke, Pamela K.; Benson, Sheila; Hayes, Monie

2015-01-01

This article is about three adult authors who are making meaning of their experiences as early career, tenure-track professors. All former secondary English language arts instructors who are responsible for preparing future secondary English teachers, the authors use Mezirow's transformative learning theory lens to examine their trajectories from…

Practicing What We Teach? An Autobiographical Reflection on Navigating Academia as a Single Mother

ERIC Educational Resources Information Center

Schlehofer, Michele

2012-01-01

Despite the contributions of feminist theory and practice to improve workplace conditions in various sectors of business and industry, academic workplaces largely remain structured around a traditionally hierarchical, male workplace model and culture, which can inhibit women's career advancement. Using autobiographical narrative, I draw upon my…

“Going Beyond the Call of Doula”: A Grounded Theory Analysis of the Diverse Roles Community-Based Doulas Play in the Lives of Pregnant and Parenting Adolescent Mothers

PubMed Central

Gentry, Quinn M.; Nolte, Kim M.; Gonzalez, Ainka; Pearson, Magan; Ivey, Symeon

2010-01-01

This article presents some of the most salient qualitative results from a larger program evaluation of pregnant and parenting adolescents who participated in a community-based doula program. Using grounded theory analysis, seven problem-solving strategies emerged that doulas apply in helping pregnant and parenting adolescents navigate multiple social and health settings that often serve as barriers to positive maternal- and child-health outcomes. The ethnographic findings of this study suggest that the doulas provide valuable assistance to pregnant and parenting adolescents by addressing social-psychological issues and socio-economic disparities. “Diverse role-taking” results in doulas helping pregnant adolescents navigate more successfully through fragmented social and health service systems that are less supportive of low-income adolescents, who are often perceived to be draining scarce resources. The findings have implications for the roles of community-based doulas assigned to low-income adolescents of color seeking to overcome obstacles and attain better educational and economic opportunities. PMID:21886419

How simple autonomous decisions evolve into robust behaviours? A review from neurorobotics, cognitive, self-organized and artificial immune systems fields.

PubMed

Fernandez-Leon, Jose A; Acosta, Gerardo G; Rozenfeld, Alejandro

2014-10-01

Researchers in diverse fields, such as in neuroscience, systems biology and autonomous robotics, have been intrigued by the origin and mechanisms for biological robustness. Darwinian evolution, in general, has suggested that adaptive mechanisms as a way of reaching robustness, could evolve by natural selection acting successively on numerous heritable variations. However, is this understanding enough for realizing how biological systems remain robust during their interactions with the surroundings? Here, we describe selected studies of bio-inspired systems that show behavioral robustness. From neurorobotics, cognitive, self-organizing and artificial immune system perspectives, our discussions focus mainly on how robust behaviors evolve or emerge in these systems, having the capacity of interacting with their surroundings. These descriptions are twofold. Initially, we introduce examples from autonomous robotics to illustrate how the process of designing robust control can be idealized in complex environments for autonomous navigation in terrain and underwater vehicles. We also include descriptions of bio-inspired self-organizing systems. Then, we introduce other studies that contextualize experimental evolution with simulated organisms and physical robots to exemplify how the process of natural selection can lead to the evolution of robustness by means of adaptive behaviors. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Neutrality and evolvability of designed protein sequences

NASA Astrophysics Data System (ADS)

Bhattacherjee, Arnab; Biswas, Parbati

2010-07-01

The effect of foldability on protein’s evolvability is analyzed by a two-prong approach consisting of a self-consistent mean-field theory and Monte Carlo simulations. Theory and simulation models representing protein sequences with binary patterning of amino acid residues compatible with a particular foldability criteria are used. This generalized foldability criterion is derived using the high temperature cumulant expansion approximating the free energy of folding. The effect of cumulative point mutations on these designed proteins is studied under neutral condition. The robustness, protein’s ability to tolerate random point mutations is determined with a selective pressure of stability (ΔΔG) for the theory designed sequences, which are found to be more robust than that of Monte Carlo and mean-field-biased Monte Carlo generated sequences. The results show that this foldability criterion selects viable protein sequences more effectively compared to the Monte Carlo method, which has a marked effect on how the selective pressure shapes the evolutionary sequence space. These observations may impact de novo sequence design and its applications in protein engineering.

Disruptive selection as a driver of evolutionary branching and caste evolution in social insects.

PubMed

Planqué, R; Powell, S; Franks, N R; van den Berg, J B

2016-11-01

Theory suggests that evolutionary branching via disruptive selection may be a relatively common and powerful force driving phenotypic divergence. Here, we extend this theory to social insects, which have novel social axes of phenotypic diversification. Our model, built around turtle ant (Cephalotes) biology, is used to explore whether disruptive selection can drive the evolutionary branching of divergent colony phenotypes that include a novel soldier caste. Soldier evolution is a recurrent theme in social insect diversification that is exemplified in the turtle ants. We show that phenotypic mutants can gain competitive advantages that induce disruptive selection and subsequent branching. A soldier caste does not generally appear before branching, but can evolve from subsequent competition. The soldier caste then evolves in association with specialized resource preferences that maximize defensive performance. Overall, our model indicates that resource specialization may occur in the absence of morphological specialization, but that when morphological specialization evolves, it is always in association with resource specialization. This evolutionary coupling of ecological and morphological specialization is consistent with recent empirical evidence, but contrary to predictions of classical caste theory. Our model provides a new theoretical understanding of the ecology of caste evolution that explicitly considers the process of adaptive phenotypic divergence and diversification. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

An evolving joint space campaign concept and the Army's role

NASA Astrophysics Data System (ADS)

Franke, Henry G., III

1992-05-01

This monograph examines the question of an evolving joint space campaign concept and the Army's role in it over the next 20 years. Analysis progresses logically through a series of topics in order to arrive at a complete picture of this evolutionary space campaign concept, as well as the Army's place in it. Space plays an increasingly important role in US military operations, particularly when tied together with advances in information management. The synergistic impact due to the combination of these two areas suggests a revolution in the nature of modern warfare which saw its emergence during the 1991 Gulf War. With this theme in mind, I review the Army's roles, missions, and historical involvement in space, then present technological opportunities and a perspective on investment strategies for military space. A detailed discussion of a near-term military space theory and current space doctrines supports the need for an accepted military space theory as a foundation for Joint and Service space doctrines, space campaign design and conduct, and space force generation. The basis for such a theory is established using Julian Corbett's maritime warfare theory as a point of departure, while recognizing that space as a unique military operating medium requires its own theory and a regime to govern the application of space forces.

The evolutionary dynamics of haplodiploidy: Genome architecture and haploid viability

PubMed Central

Blackmon, Heath; Hardy, Nate B.; Ross, Laura

2015-01-01

Haplodiploid reproduction, in which males are haploid and females are diploid, is widespread among animals, yet we understand little about the forces responsible for its evolution. The current theory is that haplodiploidy has evolved through genetic conflicts, as it provides a transmission advantage to mothers. Male viability is thought to be a major limiting factor; diploid individuals tend to harbor many recessive lethal mutations. This theory predicts that the evolution of haplodiploidy is more likely in male heterogametic lineages with few chromosomes, as genes on the X chromosome are often expressed in a haploid environment, and the fewer the chromosome number, the greater the proportion of the total genome that is X‐linked. We test this prediction with comparative phylogenetic analyses of mites, among which haplodiploidy has evolved repeatedly. We recover a negative correlation between chromosome number and haplodiploidy, find evidence that low chromosome number evolved prior to haplodiploidy, and that it is unlikely that diplodiploidy has reevolved from haplodiploid lineages of mites. These results are consistent with the predicted importance of haploid male viability. PMID:26462452

Surgical orthodontics.

PubMed

Strohl, Alexis M; Vitkus, Lauren

2017-08-01

The article reviews some commonly used orthodontic treatments as well as new strategies to assist in the correction of malocclusion. Many techniques are used in conjunction with surgical intervention and are a necessary compliment to orthognathic surgery. Basic knowledge of these practices will aid in the surgeon's ability to adequately treat the patient. Many orthodontists and surgeons are eliminating presurgical orthodontics to adopt a strategy of 'surgery first' orthodontics in orthognathic surgery. This has the benefit of immediate improvement in facial aesthetics and shorter treatment times. The advent of virtual surgical planning has helped facilitate the development of this new paradigm by making surgical planning faster and easier. Furthermore, using intraoperative surgical navigation is improving overall precision and outcomes. A variety of surgical and nonsurgical treatments may be employed in the treatment of malocclusion. It is important to be familiar with all options available and tailor the patient's treatment plan accordingly. Surgery-first orthodontics, intraoperative surgical navigation, virtual surgical planning, and 3D printing are evolving new techniques that are producing shorter treatment times and subsequently improving patient satisfaction without sacrificing long-term stability.

In-Space Networking On NASA's SCaN Testbed

NASA Technical Reports Server (NTRS)

Brooks, David; Eddy, Wesley M.; Clark, Gilbert J., III; Johnson, Sandra K.

2016-01-01

The NASA Space Communications and Navigation (SCaN) Testbed, an external payload onboard the International Space Station, is equipped with three software defined radios (SDRs) and a programmable flight computer. The purpose of the Testbed is to conduct inspace research in the areas of communication, navigation, and networking in support of NASA missions and communication infrastructure. Multiple reprogrammable elements in the end to end system, along with several communication paths and a semi-operational environment, provides a unique opportunity to explore networking concepts and protocols envisioned for the future Solar System Internet (SSI). This paper will provide a general description of the system's design and the networking protocols implemented and characterized on the testbed, including Encapsulation, IP over CCSDS, and Delay-Tolerant Networking (DTN). Due to the research nature of the implementation, flexibility and robustness are considered in the design to enable expansion for future adaptive and cognitive techniques. Following a detailed design discussion, lessons learned and suggestions for future missions and communication infrastructure elements will be provided. Plans for the evolving research on SCaN Testbed as it moves towards a more adaptive, autonomous system will be discussed.

Evolutionary Perspective on Collective Decision Making

NASA Astrophysics Data System (ADS)

Farrell, Dene; Sayama, Hiroki; Dionne, Shelley D.; Yammarino, Francis J.; Wilson, David Sloan

Team decision making dynamics are investigated from a novel perspective by shifting agency from decision makers to representations of potential solutions. We provide a new way to navigate social dynamics of collective decision making by interpreting decision makers as constituents of an evolutionary environment of an ecology of evolving solutions. We demonstrate distinct patterns of evolution with respect to three forms of variation: (1) Results with random variations in utility functions of individuals indicate that groups demonstrating minimal internal variation produce higher true utility values of group solutions and display better convergence; (2) analysis of variations in behavioral patterns within a group shows that a proper balance between selective and creative evolutionary forces is crucial to producing adaptive solutions; and (3) biased variations of the utility functions diminish the range of variation for potential solution utility, leaving only the differential of convergence performance static. We generally find that group cohesion (low random variation within a group) and composition (appropriate variation of behavioral patterns within a group) are necessary for a successful navigation of the solution space, but performance in both cases is susceptible to group level biases.

Next Generation Global Navigation Satellite Systems (GNSS) Processing at NASA CDDIS

NASA Astrophysics Data System (ADS)

Michael, B. P.; Noll, C. E.

2016-12-01

The Crustal Dynamics Data Information System (CDDIS) has been providing access to space geodesy and related data sets since 1982, and in particular, Global Navigation Satellite Systems (GNSS) data and derived products since 1992. The CDDIS became one of the Earth Observing System Data and Information System (EOSDIS) archive centers in 2007. As such, CDDIS has evolved to offer a broad range of data ingest services, from data upload, quality control, documentation, metadata extraction, and ancillary information. With a growing understanding of the needs and goals of its science users CDDIS continues to improve these services. Due to the importance of GNSS data and derived products in scientific studies over the last decade, CDDIS has seen its ingest volume explode to over 30 million files per year or more than one file per second from over hundreds of simultaneous data providers. In order to accommodate this increase and to streamline operations and fully automate the workflow, CDDIS has recently updated the data submission process and GNSS processing. This poster will cover this new ingest infrastructure, workflow, and the agile techniques applied in its development and current operations.

High accuracy navigation information estimation for inertial system using the multi-model EKF fusing adams explicit formula applied to underwater gliders.

PubMed

Huang, Haoqian; Chen, Xiyuan; Zhang, Bo; Wang, Jian

2017-01-01

The underwater navigation system, mainly consisting of MEMS inertial sensors, is a key technology for the wide application of underwater gliders and plays an important role in achieving high accuracy navigation and positioning for a long time of period. However, the navigation errors will accumulate over time because of the inherent errors of inertial sensors, especially for MEMS grade IMU (Inertial Measurement Unit) generally used in gliders. The dead reckoning module is added to compensate the errors. In the complicated underwater environment, the performance of MEMS sensors is degraded sharply and the errors will become much larger. It is difficult to establish the accurate and fixed error model for the inertial sensor. Therefore, it is very hard to improve the accuracy of navigation information calculated by sensors. In order to solve the problem mentioned, the more suitable filter which integrates the multi-model method with an EKF approach can be designed according to different error models to give the optimal estimation for the state. The key parameters of error models can be used to determine the corresponding filter. The Adams explicit formula which has an advantage of high precision prediction is simultaneously fused into the above filter to achieve the much more improvement in attitudes estimation accuracy. The proposed algorithm has been proved through theory analyses and has been tested by both vehicle experiments and lake trials. Results show that the proposed method has better accuracy and effectiveness in terms of attitudes estimation compared with other methods mentioned in the paper for inertial navigation applied to underwater gliders. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

"Utilizing" signal detection theory.

PubMed

Lynn, Spencer K; Barrett, Lisa Feldman

2014-09-01

What do inferring what a person is thinking or feeling, judging a defendant's guilt, and navigating a dimly lit room have in common? They involve perceptual uncertainty (e.g., a scowling face might indicate anger or concentration, for which different responses are appropriate) and behavioral risk (e.g., a cost to making the wrong response). Signal detection theory describes these types of decisions. In this tutorial, we show how incorporating the economic concept of utility allows signal detection theory to serve as a model of optimal decision making, going beyond its common use as an analytic method. This utility approach to signal detection theory clarifies otherwise enigmatic influences of perceptual uncertainty on measures of decision-making performance (accuracy and optimality) and on behavior (an inverse relationship between bias magnitude and sensitivity optimizes utility). A "utilized" signal detection theory offers the possibility of expanding the phenomena that can be understood within a decision-making framework. © The Author(s) 2014.

“UTILIZING” SIGNAL DETECTION THEORY

PubMed Central

Lynn, Spencer K.; Barrett, Lisa Feldman

2014-01-01

What do inferring what a person is thinking or feeling, deciding to report a symptom to your doctor, judging a defendant’s guilt, and navigating a dimly lit room have in common? They involve perceptual uncertainty (e.g., a scowling face might indicate anger or concentration, which engender different appropriate responses), and behavioral risk (e.g., a cost to making the wrong response). Signal detection theory describes these types of decisions. In this tutorial we show how, by incorporating the economic concept of utility, signal detection theory serves as a model of optimal decision making, beyond its common use as an analytic method. This utility approach to signal detection theory highlights potentially enigmatic influences of perceptual uncertainty on measures of decision-making performance (accuracy and optimality) and on behavior (a functional relationship between bias and sensitivity). A “utilized” signal detection theory offers the possibility of expanding the phenomena that can be understood within a decision-making framework. PMID:25097061

Adaptation to Temporally Fluctuating Environments by the Evolution of Maternal Effects.

PubMed

Dey, Snigdhadip; Proulx, Stephen R; Teotónio, Henrique

2016-02-01

All organisms live in temporally fluctuating environments. Theory predicts that the evolution of deterministic maternal effects (i.e., anticipatory maternal effects or transgenerational phenotypic plasticity) underlies adaptation to environments that fluctuate in a predictably alternating fashion over maternal-offspring generations. In contrast, randomizing maternal effects (i.e., diversifying and conservative bet-hedging), are expected to evolve in response to unpredictably fluctuating environments. Although maternal effects are common, evidence for their adaptive significance is equivocal since they can easily evolve as a correlated response to maternal selection and may or may not increase the future fitness of offspring. Using the hermaphroditic nematode Caenorhabditis elegans, we here show that the experimental evolution of maternal glycogen provisioning underlies adaptation to a fluctuating normoxia-anoxia hatching environment by increasing embryo survival under anoxia. In strictly alternating environments, we found that hermaphrodites evolved the ability to increase embryo glycogen provisioning when they experienced normoxia and to decrease embryo glycogen provisioning when they experienced anoxia. At odds with existing theory, however, populations facing irregularly fluctuating normoxia-anoxia hatching environments failed to evolve randomizing maternal effects. Instead, adaptation in these populations may have occurred through the evolution of fitness effects that percolate over multiple generations, as they maintained considerably high expected growth rates during experimental evolution despite evolving reduced fecundity and reduced embryo survival under one or two generations of anoxia. We develop theoretical models that explain why adaptation to a wide range of patterns of environmental fluctuations hinges on the existence of deterministic maternal effects, and that such deterministic maternal effects are more likely to contribute to adaptation than randomizing maternal effects.

Adaptation to Temporally Fluctuating Environments by the Evolution of Maternal Effects

PubMed Central

Dey, Snigdhadip; Proulx, Stephen R.; Teotónio, Henrique

2016-01-01

All organisms live in temporally fluctuating environments. Theory predicts that the evolution of deterministic maternal effects (i.e., anticipatory maternal effects or transgenerational phenotypic plasticity) underlies adaptation to environments that fluctuate in a predictably alternating fashion over maternal-offspring generations. In contrast, randomizing maternal effects (i.e., diversifying and conservative bet-hedging), are expected to evolve in response to unpredictably fluctuating environments. Although maternal effects are common, evidence for their adaptive significance is equivocal since they can easily evolve as a correlated response to maternal selection and may or may not increase the future fitness of offspring. Using the hermaphroditic nematode Caenorhabditis elegans, we here show that the experimental evolution of maternal glycogen provisioning underlies adaptation to a fluctuating normoxia–anoxia hatching environment by increasing embryo survival under anoxia. In strictly alternating environments, we found that hermaphrodites evolved the ability to increase embryo glycogen provisioning when they experienced normoxia and to decrease embryo glycogen provisioning when they experienced anoxia. At odds with existing theory, however, populations facing irregularly fluctuating normoxia–anoxia hatching environments failed to evolve randomizing maternal effects. Instead, adaptation in these populations may have occurred through the evolution of fitness effects that percolate over multiple generations, as they maintained considerably high expected growth rates during experimental evolution despite evolving reduced fecundity and reduced embryo survival under one or two generations of anoxia. We develop theoretical models that explain why adaptation to a wide range of patterns of environmental fluctuations hinges on the existence of deterministic maternal effects, and that such deterministic maternal effects are more likely to contribute to adaptation than randomizing maternal effects. PMID:26910440

My Journey to Become a Teacher Educator

ERIC Educational Resources Information Center

Tannehill, Deborah

2016-01-01

Purpose: Social theory of learning speaks to the social nature of our lives and our attempts to understand both what and how we learn from it. My experiences are built upon and reside with the social context in which they evolved. In this lecture, I will focus on my own experiences and how I interpreted them through social theory of learning that…

Cattell-Horn-Carroll Cognitive-Achievement Relations: What We Have Learned from the Past 20 Years of Research

ERIC Educational Resources Information Center

McGrew, Kevin S.; Wendling, Barbara J.

2010-01-01

Contemporary Cattell-Horn-Carroll (CHC) theory of cognitive abilities has evolved over the past 20 years and serves as the theoretical foundation for a number of current cognitive ability assessments. CHC theory provides a means by which we can better understand the relationships between cognitive abilities and academic achievement, an important…

A Tangled Web of Terms: The Overlap and Unique Contribution of Involvement, Engagement, and Integration to Understanding College Student Success

ERIC Educational Resources Information Center

Wolf-Wendel, Lisa; Ward, Kelly; Kinzie, Jillian

2009-01-01

Established theories and constructs long associated with student success, including involvement, engagement, and integration, provide common language and a body of knowledge to inform understanding of the challenges currently facing higher education. This paper examines how the theories and terms have evolved, explores how the terms are currently…

Practitioner Beware! A Critical Reflection on the Theoretical Assumptions that Inform Practice

ERIC Educational Resources Information Center

Walker, Karen

2004-01-01

Underpinning the practice of career counsellors is a range of various theories and perspectives. The concept of self-esteem is a term frequently used by those in the helping professions and often with little regard for its limitations. This article argues that careers counsellors need to keep up-to-date with evolving theories that inform their…

Enhanced orbit determination filter: Inclusion of ground system errors as filter parameters

NASA Technical Reports Server (NTRS)

Masters, W. C.; Scheeres, D. J.; Thurman, S. W.

1994-01-01

The theoretical aspects of an orbit determination filter that incorporates ground-system error sources as model parameters for use in interplanetary navigation are presented in this article. This filter, which is derived from sequential filtering theory, allows a systematic treatment of errors in calibrations of transmission media, station locations, and earth orientation models associated with ground-based radio metric data, in addition to the modeling of the spacecraft dynamics. The discussion includes a mathematical description of the filter and an analytical comparison of its characteristics with more traditional filtering techniques used in this application. The analysis in this article shows that this filter has the potential to generate navigation products of substantially greater accuracy than more traditional filtering procedures.

Higher rates of sex evolve in spatially heterogeneous environments.

PubMed

Becks, Lutz; Agrawal, Aneil F

2010-11-04

The evolution and maintenance of sexual reproduction has puzzled biologists for decades. Although this field is rich in hypotheses, experimental evidence is scarce. Some important experiments have demonstrated differences in evolutionary rates between sexual and asexual populations; other experiments have documented evolutionary changes in phenomena related to genetic mixing, such as recombination and selfing. However, direct experiments of the evolution of sex within populations are extremely rare (but see ref. 12). Here we use the rotifer, Brachionus calyciflorus, which is capable of both sexual and asexual reproduction, to test recent theory predicting that there is more opportunity for sex to evolve in spatially heterogeneous environments. Replicated experimental populations of rotifers were maintained in homogeneous environments, composed of either high- or low-quality food habitats, or in heterogeneous environments that consisted of a mix of the two habitats. For populations maintained in either type of homogeneous environment, the rate of sex evolves rapidly towards zero. In contrast, higher rates of sex evolve in populations experiencing spatially heterogeneous environments. The data indicate that the higher level of sex observed under heterogeneity is not due to sex being less costly or selection against sex being less efficient; rather sex is sufficiently advantageous in heterogeneous environments to overwhelm its inherent costs. Counter to some alternative theories for the evolution of sex, there is no evidence that genetic drift plays any part in the evolution of sex in these populations.

Experimental evolution of bet hedging under manipulated environmental uncertainty in Neurospora crassa.

PubMed

Graham, Jeffrey K; Smith, Myron L; Simons, Andrew M

2014-07-22

All organisms are faced with environmental uncertainty. Bet-hedging theory expects unpredictable selection to result in the evolution of traits that maximize the geometric-mean fitness even though such traits appear to be detrimental over the shorter term. Despite the centrality of fitness measures to evolutionary analysis, no direct test of the geometric-mean fitness principle exists. Here, we directly distinguish between predictions of competing fitness maximization principles by testing Cohen's 1966 classic bet-hedging model using the fungus Neurospora crassa. The simple prediction is that propagule dormancy will evolve in proportion to the frequency of 'bad' years, whereas the prediction of the alternative arithmetic-mean principle is the evolution of zero dormancy as long as the expectation of a bad year is less than 0.5. Ascospore dormancy fraction in N. crassa was allowed to evolve under five experimental selection regimes that differed in the frequency of unpredictable 'bad years'. Results were consistent with bet-hedging theory: final dormancy fraction in 12 genetic lineages across 88 independently evolving samples was proportional to the frequency of bad years, and evolved both upwards and downwards as predicted from a range of starting dormancy fractions. These findings suggest that selection results in adaptation to variable rather than to expected environments. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Anatomical Network Analysis Shows Decoupling of Modular Lability and Complexity in the Evolution of the Primate Skull

PubMed Central

Esteve-Altava, Borja; Boughner, Julia C.; Diogo, Rui; Villmoare, Brian A.; Rasskin-Gutman, Diego

2015-01-01

Modularity and complexity go hand in hand in the evolution of the skull of primates. Because analyses of these two parameters often use different approaches, we do not know yet how modularity evolves within, or as a consequence of, an also-evolving complex organization. Here we use a novel network theory-based approach (Anatomical Network Analysis) to assess how the organization of skull bones constrains the co-evolution of modularity and complexity among primates. We used the pattern of bone contacts modeled as networks to identify connectivity modules and quantify morphological complexity. We analyzed whether modularity and complexity evolved coordinately in the skull of primates. Specifically, we tested Herbert Simon’s general theory of near-decomposability, which states that modularity promotes the evolution of complexity. We found that the skulls of extant primates divide into one conserved cranial module and up to three labile facial modules, whose composition varies among primates. Despite changes in modularity, statistical analyses reject a positive feedback between modularity and complexity. Our results suggest a decoupling of complexity and modularity that translates to varying levels of constraint on the morphological evolvability of the primate skull. This study has methodological and conceptual implications for grasping the constraints that underlie the developmental and functional integration of the skull of humans and other primates. PMID:25992690

Navigating Guilt, Shame, and Fear of Appearing Racist: A Conceptual Model of Antiracist White Feminist Identity Development

ERIC Educational Resources Information Center

Linder, Chris

2015-01-01

In this study, I employed narrative inquiry supported by intersectionality theory to explore the experiences of 6 antiracist, White, feminist undergraduate women. A conceptual model of antiracist identity development emerged from the data. Participants described vivid experiences with guilt, shame, and fear that kept them from engaging in allied…

Affirming Race, Diversity, and Equity through Black and Latinx Students' Lived Experiences

ERIC Educational Resources Information Center

Vue, Rican; Haslerig, Siduri Jayaram; Allen, Walter R.

2017-01-01

Immediately after President Obama's successful campaign, many hypothesized that the United States had entered a post-racial era. This study uses critical race theory to examine how high-achieving Black and Latinx college students make meaning of and navigate affirmative action policy discourses in an era of colorblind racial politics.…

Employing Critical Race Theory Lens in Examining Black Graduate Students' Experience in Higher Education: Implications for Counseling

ERIC Educational Resources Information Center

Clay, April M.

2010-01-01

Black students are a visibly diminishing population among college degree recipients, yet many manage to succeed in graduate school. This research was designed to broaden the understanding of Black graduate students' challenges, successes, and navigation strategies with implications for counselors, faculty and mentors working with Black…

Assisting in the Management of Faculty Role Stress: Recommendations for Faculty Developers

ERIC Educational Resources Information Center

Richards, K. Andrew R.; Levesque-Bristol, Chantal

2016-01-01

Role theory is a sociological perspective that examines the ways in which interactions with others in a social environment can lead to role-related stress. Faculty may suffer from role-related stressors such as role conflict, ambiguity, and overload as they navigate the job facets of research, engagement, and teaching. This role stress can result…

Primary Discourse and Expressive Oral Language in a Kindergarten Student

ERIC Educational Resources Information Center

Fiano, Darcy A.

2014-01-01

This seven-month ethnographic case study elucidated a kindergarten student's navigation through her first formal schooling experience with relation to expressive oral language. Gee's theory of Discourses and methodology of discourse analysis were used to examine expressive oral language in use. Two discursive contexts germane to…

I Grew up Straight 'hood: Unpacking the Intelligences of Working-Class Latino Male College Students in North Carolina

ERIC Educational Resources Information Center

Carrillo, Juan F.

2016-01-01

Primarily drawing from the Mestiz@ Theory of Intelligences (Carrillo, 2013), this article examines how working class Latino male college students in North Carolina navigate multiple cultural worlds and excel academically. This work addresses current gaps in the literature that largely fail to unpack the experiences of academically successful…

Male Teachers of Color Take a Lesson from Each Other

ERIC Educational Resources Information Center

Bristol, Travis J.

2015-01-01

The author tells of the experience of co-founding a group of male teachers of color within the Boston Teacher Residency program. The group's theory of action was that professional development focused on addressing the unique challenges of male teachers of color would help these teachers develop tools and strategies to navigate their school…

Theory Ain't Practice: Four Novice Researchers Navigate Dilemmas of Representation within Immigrant Populations

ERIC Educational Resources Information Center

Aleixo, Marina; Hansen, Sarah; Horii, Sachiko; Un, Silvy

2014-01-01

This article illuminates instances in which four graduate students have struggled with issues of representation--of themselves and of immigrant participants--at their research sites and in their writing. These dilemmas are situated within the literature on the politics of representation in qualitative research. Although these dilemmas are not…

Critical Information Literacy beyond the University: Lessons from Service in a Women's Health Interest Group

ERIC Educational Resources Information Center

Fountain, Kathleen Carlisle

2013-01-01

Library instruction methods most frequently focus on teaching students searching skills to navigate the maze of library databases to locate appropriate research materials. The current theory of critical information literacy instruction calls on librarians to spend more of their time in the classroom focused on understanding the social, political,…

Adding Academics to the Work/Family Puzzle: Graduate Student Parents in Higher Education and Student Affairs

ERIC Educational Resources Information Center

Sallee, Margaret W.

2015-01-01

Based on interviews with 18 parents who were enrolled in higher education and student affairs master's programs and also employed on college and university campuses, this article explores the ways that student parents navigate their academic, familial, and professional responsibilities. Using role conflict theory as a theoretical guide, this study…

Queer Outings: Uncomfortable Stories about the Subjects of Post-Structural School Ethnography

ERIC Educational Resources Information Center

Youdell, Deborah

2010-01-01

In this paper, I consider the abiding value as well as the limits of queer; navigating the contradictions of a politics and ethnographic practice based on a refutation of an abiding subject; resisting subjectivation and needing recognition; and "coming out" in school ethnography framed by queer theory. The paper moves from the work of Michel…

When Shoes Become Hammers: Goal-Derived Categorization Training Enhances Problem-Solving Performance

ERIC Educational Resources Information Center

Chrysikou, Evangelia G.

2006-01-01

Problem-solving theories have not examined how solvers navigate their knowledge to interpret problem situations or to plan strategies toward goals. In this article, the author argues that success in problem solving depends on the solver's ability to construct goal-derived categories, namely categories that are formed ad hoc to serve goals during…

Experiences of cancer patients in a patient navigation program: a qualitative systematic review.

PubMed

Tan, Clarice Hwee Hoon; Wilson, Sally; McConigley, Ruth

2015-03-12

A patient navigation program is a model of care which entails trained personnel providing individualized and assistive care to adult oncology patients to help the patients overcome barriers. A further aim of the program is to achieve continuity of care as patients experience the complex healthcare system. Patient navigation is a new model of care in many institutions, and as such the experiences of patients in the patient navigation program remains inconclusive. The review seeks to understand the experiences of adult patients in patient navigation programs and how patient navigators impact the challenges patients encounter in the cancer care continuum. Participants of interest were adult cancer patients more than 18 years of age who are receiving or have received cancer care and are in a patient navigation program or had been in a hospital patient navigation program. Types of intervention(s)/phenomena of interest: The phenomenon of interest was the experiences of adult cancer patients who used patient navigation programs in hospital including how patient navigators impact on the challenges patients encounter in the cancer care continuum. Types of studies: This review considered studies that focused on qualitative data including, but not limited to, designs such as phenomenology, grounded theory, action research and exploratory studies. The review includes patient navigation programs within a hospital setting. Types of outcome: The review sought to understand the experiences of patients with cancer in patient navigation programs in the hospital. A three-step search strategy was used. An initial search to identify keywords was undertaken in PubMed and Science Direct followed by an expanded search using all identified keywords and index terms specific to each included database. The reference lists of included papers were then searched for any other relevant studies. Each paper was assessed independently by two reviewers for methodological quality using the Joanna Briggs Institute Qualitative Assessment and Review Instrument. Any disagreements that arose between the reviewers were resolved through discussion. Data extraction and synthesis was conducted using standardized data extraction and synthesis tools from JBI-QARI. The 17 unequivocal and credible findings of included studies were categorized according to similarity of meaning and developed into three synthesized findings. Three papers were included in the review. The three synthesized findings from the 17 findings extracted from the papers were: (1) Emotional empowerment: patient navigators need to be present with patients at key phases of the cancer care continuum and assure patients of their accessibility; (2) Knowledge empowerment: patient navigators need to explore and manage the needs and expectations of patients so that the healthcare team and patient have the same understanding of treatment goals and plans; and (3) Bridging the gaps: patient navigators need to ensure practical assistance is provided for patients to ensure continuity of care even at the completion of the treatment regimen. The presence of a patient navigator provides strong support to the patients when experiencing disruption from cancer diagnosis and treatment. The emotional isolation they experience lessens with the assurance that there is always a consistent and constant contact point they can fall back on. The logistic and practical help given by the navigators allows patients to take time to process information and make sense of what is happening. The Joanna Briggs Institute.

What would researchers like to improve in communication initiatives?

NASA Astrophysics Data System (ADS)

Russo, Pedro

2015-08-01

One of the most important current trends in astronomy communication has been “change”. The field of astronomy communication has rapidly evolved in just the past few years, as new techniques and technologies have been adopted. Research astronomy has also visibly changed, as automation of survey systems and the launch of new telescopes has produced a tsunami of big data sets. Today, scientists and communicators must work together to navigate the raging waters of this data flood as they strive to keep our tech-savvy society informed. This invited talk will be given by Alain Doressoundiram (Observatoire de Paris, Centre National de la Recherche Scientifique, France) TBC

Reprogramming the virulence: Insect defense molecules navigating the epigenetic landscape of Metarhizium robertsii.

PubMed

Hussain, Abid

2018-01-01

Metarhizium species are the leading bio-control agents well characterized regarding pathogenicity to agricultural, forest, public health, stored grains and urban insect pests. They infect the target host through the tight conidial adherence with the insect cuticle. Conidial binding to the insect cuticle drive the systematic integrated disease development events in target host to impart pathogenesis. However, there is growing evidence that virulence of the pathogen is directly related with proteolytic enzymes including metalloproteinases, chymotrypsin-like proteinases and subtilisin-like proteinases. Successful host pathogenesis is the selection of right set of virulence-related proteinases, which evolved as a result of host-pathogen coevolution.

Performance of preproduction model cesium beam frequency standards for spacecraft applications

NASA Technical Reports Server (NTRS)

Levine, M. W.

1978-01-01

A cesium beam frequency standards for spaceflight application on Navigation Development Satellites was designed and fabricated and preliminary testing was completed. The cesium standard evolved from an earlier prototype model launched aboard NTS-2 and the engineering development model to be launched aboard NTS satellites during 1979. A number of design innovations, including a hybrid analog/digital integrator and the replacement of analog filters and phase detectors by clocked digital sampling techniques are discussed. Thermal and thermal-vacuum testing was concluded and test data are presented. Stability data for 10 to 10,000 seconds averaging interval, measured under laboratory conditions, are shown.

Member Input Sought to Ensure AGU's Continued Success

NASA Astrophysics Data System (ADS)

Grove, Timothy L.

2008-11-01

As an organization, AGU is indeed fortunate. Our Union has a growing membership worldwide with an average annual increase of 5.9% over the last 5 years. We are financially strong; we have planned carefully and managed our assets and our annual budgets so that we are able to navigate difficult times. Our Fall Meeting is ``the'' event for Earth and space scientists from more than 100 countries. Our publications continue to grow and evolve. Our outreach programs are gaining recognition in the communities we serve. Our development efforts are strengthening our ability to do more without taxing the revenues from meetings and publications. AGU is a preeminent scientific society.

Geosynchronous platform definition study. Volume 5: Geosynchronous platform synthesis

NASA Technical Reports Server (NTRS)

1973-01-01

The development is described of the platform configurations, support subsystems, mission equipment, and servicing concepts. A common support module is developed; subsystem concepts are traded off; data relay, TDRS, earth observational, astro-physics, and advanced navigation and traffic control mission equipment concepts are postulated; and ancillary equipment required for delivery and on-orbit servicing interfaces with geosynchronous platforms is grossly defined. The general approach was to develop a platform concept capable of evolving through three on-orbit servicing modes: remote, EVA, and shirtsleeve. The definition of the equipment is to the assembly level. Weight, power, and volumetric data are compiled for all the platforms.

What has driven the evolution of multiple cone classes in visual systems: object contrast enhancement or light flicker elimination?

PubMed

Sabbah, Shai; Hawryshyn, Craig W

2013-07-04

Two competing theories have been advanced to explain the evolution of multiple cone classes in vertebrate eyes. These two theories have important, but different, implications for our understanding of the design and tuning of vertebrate visual systems. The 'contrast theory' proposes that multiple cone classes evolved in shallow-water fish to maximize the visual contrast of objects against diverse backgrounds. The competing 'flicker theory' states that multiple cone classes evolved to eliminate the light flicker inherent in shallow-water environments through antagonistic neural interactions, thereby enhancing object detection. However, the selective pressures that have driven the evolution of multiple cone classes remain largely obscure. We show that two critical assumptions of the flicker theory are violated. We found that the amplitude and temporal frequency of flicker vary over the visible spectrum, precluding its cancellation by simple antagonistic interactions between the output signals of cones. Moreover, we found that the temporal frequency of flicker matches the frequency where sensitivity is maximal in a wide range of fish taxa, suggesting that the flicker may actually enhance the detection of objects. Finally, using modeling of the chromatic contrast between fish pattern and background under flickering illumination, we found that the spectral sensitivity of cones in a cichlid focal species is optimally tuned to maximize the visual contrast between fish pattern and background, instead of to produce a flicker-free visual signal. The violation of its two critical assumptions substantially undermines support for the flicker theory as originally formulated. While this alone does not support the contrast theory, comparison of the contrast and flicker theories revealed that the visual system of our focal species was tuned as predicted by the contrast theory rather than by the flicker theory (or by some combination of the two). Thus, these findings challenge key assumptions of the flicker theory, leaving the contrast theory as the most parsimonious and tenable account of the evolution of multiple cone classes.

De novo insertion of an intron into the mammalian sex determining gene, SRY

PubMed Central

O’Neill, Rachel J. Waugh; Brennan, Francine E.; Delbridge, Margaret L.; Crozier, Ross H.; Graves, Jennifer A. Marshall

1998-01-01

Two theories have been proposed to explain the evolution of introns within eukaryotic genes. The introns early theory, or “exon theory of genes,” proposes that introns are ancient and that recombination within introns provided new exon structure, and thus new genes. The introns late theory, or “insertional theory of introns,” proposes that ancient genes existed as uninterrupted exons and that introns have been introduced during the course of evolution. There is still controversy as to how intron–exon structure evolved and whether the majority of introns are ancient or novel. Although there is extensive evidence in support of the introns early theory, phylogenetic comparisons of several genes indicate recent gain and loss of introns within these genes. However, no example has been shown of a protein coding gene, intronless in its ancestral form, which has acquired an intron in a derived form. The mammalian sex determining gene, SRY, is intronless in all mammals studied to date, as is the gene from which it recently evolved. However, we report here comparisons of genomic and cDNA sequences that now provide evidence of a de novo insertion of an intron into the SRY gene of dasyurid marsupials. This recently (approximately 45 million years ago) inserted sequence is not homologous with known transposable elements. Our data demonstrate that introns may be inserted as spliced units within a developmentally crucial gene without disrupting its function. PMID:9465071

Three visions of doctoring: a Gadamerian dialogue.

PubMed

Chin-Yee, Benjamin; Messinger, Atara; Young, L Trevor

2018-04-16

Medicine in the twenty-first century faces an 'identity crisis,' as it grapples with the emergence of various 'ways of knowing,' from evidence-based and translational medicine, to narrative-based and personalized medicine. While each of these approaches has uniquely contributed to the advancement of patient care, this pluralism is not without tension. Evidence-based medicine is not necessary individualized; personalized medicine may be individualized but is not necessarily person-centered. As novel technologies and big data continue to proliferate today, the focus of medical practice is shifting away from the dialogic encounter between doctor and patient, threatening the loss of humanism that many view as integral to medicine's identity. As medical trainees, we struggle to synthesize medicine's diverse and evolving 'ways of knowing' and to create a vision of doctoring that integrates new forms of medical knowledge into the provision of person-centered care. In search of answers, we turned to twentieth-century philosopher Hans-Georg Gadamer, whose unique outlook on "health" and "healing," we believe, offers a way forward in navigating medicine's 'messy pluralism.' Drawing inspiration from Gadamer's emphasis on dialogue and 'practical wisdom' (phronesis), we initiated a dialogue with the dean of our medical school to address the question of how medical trainees and practicing clinicians alike can work to create a more harmonious pluralism in medicine today. We propose that implementing a pluralistic approach ultimately entails 'bridging' the current divide between scientific theory and the practical art of healing, and involves an iterative and dialogic process of asking questions and seeking answers.

Dangerous Pathogens 2000

DTIC Science & Technology

2000-12-01

Medicine, Baltimore, MD, USA 21201. The genus Rickettsia includes bacterial agents responsible for some of the most historically significant and severe...theory, the Evolutionary Theory, postulates that the different members of the genus Treponema evolved from a single organism responding to changes in the...previously (Feodorova et al, 1999), only one of them (11172) was stereotyped as Y pseudotuberculosis IfL Y pseudotuberculisis 1113 reacted with MCA against Y

Dr Google and the consumer: a qualitative study exploring the navigational needs and online health information-seeking behaviors of consumers with chronic health conditions.

PubMed

Lee, Kenneth; Hoti, Kreshnik; Hughes, Jeffery David; Emmerton, Lynne

2014-12-02

The abundance of health information available online provides consumers with greater access to information pertinent to the management of health conditions. This is particularly important given an increasing drive for consumer-focused health care models globally, especially in the management of chronic health conditions, and in recognition of challenges faced by lay consumers with finding, understanding, and acting on health information sourced online. There is a paucity of literature exploring the navigational needs of consumers with regards to accessing online health information. Further, existing interventions appear to be didactic in nature, and it is unclear whether such interventions appeal to consumers' needs. Our goal was to explore the navigational needs of consumers with chronic health conditions in finding online health information within the broader context of consumers' online health information-seeking behaviors. Potential barriers to online navigation were also identified. Semistructured interviews were conducted with adult consumers who reported using the Internet for health information and had at least one chronic health condition. Participants were recruited from nine metropolitan community pharmacies within Western Australia, as well as through various media channels. Interviews were audio-recorded, transcribed verbatim, and then imported into QSR NVivo 10. Two established approaches to thematic analysis were adopted. First, a data-driven approach was used to minimize potential bias in analysis and improve construct and criterion validity. A theory-driven approach was subsequently used to confirm themes identified by the former approach and to ensure identified themes were relevant to the objectives. Two levels of analysis were conducted for both data-driven and theory-driven approaches: manifest-level analysis, whereby face-value themes were identified, and latent-level analysis, whereby underlying concepts were identified. We conducted 17 interviews, with data saturation achieved by the 14th interview. While we identified a broad range of online health information-seeking behaviors, most related to information discussed during consumer-health professional consultations such as looking for information about medication side effects. The barriers we identified included intrinsic barriers, such as limited eHealth literacy, and extrinsic barriers, such as the inconsistency of information between different online sources. The navigational needs of our participants were extrinsic in nature and included health professionals directing consumers to appropriate online resources and better filtering of online health information. Our participants' online health information-seeking behaviors, reported barriers, and navigational needs were underpinned by the themes of trust, patient activation, and relevance. This study suggests that existing interventions aimed to assist consumers with navigating online health information may not be what consumers want or perceive they need. eHealth literacy and patient activation appear to be prevalent concepts in the context of consumers' online health information-seeking behaviors. Furthermore, the role for health professionals in guiding consumers to quality online health information is highlighted.

Coalition Factor in the Evolution of Non-Kin Altruism

NASA Astrophysics Data System (ADS)

Dessalles, Jean-Louis

Animal behavior is often altruistic. In the frame of the theory of natural selection, altruism can only exist under specific conditions like kin selection or reciprocal cooperation. We show that reciprocal cooperation, which is generally invoked to explain non-kin altruism, requires very restrictive conditions to be stable. Some of these conditions are not met in many cases of altruism observed in nature. In search of another explanation of non-kin altruism, we consider Zahavis's theory of prestige. We extend it to propose a "political" model of altruism. We give evidence showing that non-kin altruism can evolve in the context of inter-subgroup competition. Under such circumstances, altruistic behavior can be used by individuals to advertise their quality as efficient coalition members. In this model, only abilities which positively correlate with the subgroup success can evolve into altruistic behaviors.

Quantization of systems with temporally varying discretization. II. Local evolution moves

NASA Astrophysics Data System (ADS)

Höhn, Philipp A.

2014-10-01

Several quantum gravity approaches and field theory on an evolving lattice involve a discretization changing dynamics generated by evolution moves. Local evolution moves in variational discrete systems (1) are a generalization of the Pachner evolution moves of simplicial gravity models, (2) update only a small subset of the dynamical data, (3) change the number of kinematical and physical degrees of freedom, and (4) generate a dynamical (or canonical) coarse graining or refining of the underlying discretization. To systematically explore such local moves and their implications in the quantum theory, this article suitably expands the quantum formalism for global evolution moves, constructed in Paper I [P. A. Höhn, "Quantization of systems with temporally varying discretization. I. Evolving Hilbert spaces," J. Math. Phys. 55, 083508 (2014); e-print arXiv:1401.6062 [gr-qc

A Novel Adaptive H∞ Filtering Method with Delay Compensation for the Transfer Alignment of Strapdown Inertial Navigation Systems.

PubMed

Lyu, Weiwei; Cheng, Xianghong

2017-11-28

Transfer alignment is always a key technology in a strapdown inertial navigation system (SINS) because of its rapidity and accuracy. In this paper a transfer alignment model is established, which contains the SINS error model and the measurement model. The time delay in the process of transfer alignment is analyzed, and an H∞ filtering method with delay compensation is presented. Then the H∞ filtering theory and the robust mechanism of H∞ filter are deduced and analyzed in detail. In order to improve the transfer alignment accuracy in SINS with time delay, an adaptive H∞ filtering method with delay compensation is proposed. Since the robustness factor plays an important role in the filtering process and has effect on the filtering accuracy, the adaptive H∞ filter with delay compensation can adjust the value of robustness factor adaptively according to the dynamic external environment. The vehicle transfer alignment experiment indicates that by using the adaptive H∞ filtering method with delay compensation, the transfer alignment accuracy and the pure inertial navigation accuracy can be dramatically improved, which demonstrates the superiority of the proposed filtering method.

Exploring reforms while learning to teach science: Facilitating exploration of theory-practice relationships in a teacher education study group

NASA Astrophysics Data System (ADS)

Foster, Jacob G.

This dissertation inserts a new view into an old problem in teacher education. The study explores the theory-practice gap, the large distance between what preservice science teachers experience in schools, are able to enact, and are told they should hold themselves to in their practice. It does so by narrowing the focus of analysis to a secondary science study group and examining how the facilitator uses sociocultural constructivism to promote discussion. The analysis surfaces key communicative moves made by the facilitator and preservice teachers that yield fruitful discussion of theory-practice relationships. Additionally, the study's use of discourse analysis as a methodology and intertextuality as a conceptual framework opens new directions for applied sociolinguistic research and scholarship in science teacher education. Findings from the study focus on what was discussed and how explorations of theory-practice relationships were facilitated. Preservice teachers in the study group engaged in meaningful conversations about constructivist theory and its application to their students and teaching of science. They discussed many science education topics such as planning science lessons that actively engage students, assessment of content understanding, and management of content-based activities. Discussions of broader science education goals, including implementation of inquiry or development of collaborative communities, were not promoted. Examination of the facilitation illuminates a number of strategies found to be helpful in supporting these explorations. This study shows that facilitation can successfully support preservice teachers to construct understanding of social constructivist assumptions underlying the National Science Education Standards (NSES), as well as a few components of the Standards themselves. The focus on the underlying assumptions suggests that science teacher education should focus on these so that preservice teachers can build a strong foundation from which to later implement broader science education reform efforts. The study group serves as a bridging structure between university courses and classroom experiences to support preservice teacher navigation of theory-practice relationships in the context of their classroom teaching. The study group contributes to helping preservice teachers navigate the theory-practice gap by complementing other teacher education structures to achieve this long-standing goal.

Rethinking niche evolution: experiments with natural communities of Protozoa in pitcher plants.

PubMed

Miller, Thomas E; Moran, Emma R; terHorst, Casey P

2014-08-01

Classic niche theory predicts that competing species will evolve to use different resources and interact less, whereas recent niche-converge ideas predict that species evolve to use similar resources and interact more. Most data supporting niche evolution are based on observations of contemporary niche use, whereas experimental support is quite sparse. We followed the evolution of four species of Protozoa during succession in the water-filled leaves of the pitcher plant, Sarracenia purpurea, and found that evolution in multispecies systems follows a surprising pattern. Over several hundred generations, weak competitors evolved to be stronger, while strong competitors evolved to become weaker, which does not conform to expectations of either niche divergence or convergence. Evolution in this system appears to occur in response to characteristics of a suite of several competitors in the community, rather than pairwise interactions. Ecologists may need to rethink the roles of competition and evolution in structuring communities.

Biophysical models of protein evolution: Understanding the patterns of evolutionary sequence divergence

PubMed Central

Echave, Julian; Wilke, Claus O.

2018-01-01

For decades, rates of protein evolution have been interpreted in terms of the vague concept of “functional importance”. Slowly evolving proteins or sites within proteins were assumed to be more functionally important and thus subject to stronger selection pressure. More recently, biophysical models of protein evolution, which combine evolutionary theory with protein biophysics, have completely revolutionized our view of the forces that shape sequence divergence. Slowly evolving proteins have been found to evolve slowly because of selection against toxic misfolding and misinteractions, linking their rate of evolution primarily to their abundance. Similarly, most slowly evolving sites in proteins are not directly involved in function, but mutating them has large impacts on protein structure and stability. Here, we review the studies of the emergent field of biophysical protein evolution that have shaped our current understanding of sequence divergence patterns. We also propose future research directions to develop this nascent field. PMID:28301766

Stellar structure and compact objects before 1940: Towards relativistic astrophysics

NASA Astrophysics Data System (ADS)

Bonolis, Luisa

2017-06-01

Since the mid-1920s, different strands of research used stars as "physics laboratories" for investigating the nature of matter under extreme densities and pressures, impossible to realize on Earth. To trace this process this paper is following the evolution of the concept of a dense core in stars, which was important both for an understanding of stellar evolution and as a testing ground for the fast-evolving field of nuclear physics. In spite of the divide between physicists and astrophysicists, some key actors working in the cross-fertilized soil of overlapping but different scientific cultures formulated models and tentative theories that gradually evolved into more realistic and structured astrophysical objects. These investigations culminated in the first contact with general relativity in 1939, when J. Robert Oppenheimer and his students George Volkoff and Hartland Snyder systematically applied the theory to the dense core of a collapsing neutron star. This pioneering application of Einstein's theory to an astrophysical compact object can be regarded as a milestone in the path eventually leading to the emergence of relativistic astrophysics in the early 1960s.

The evolution of prestige: freely conferred deference as a mechanism for enhancing the benefits of cultural transmission.

PubMed

Henrich, J; Gil-White, F J.

2001-05-01

This paper advances an "information goods" theory that explains prestige processes as an emergent product of psychological adaptations that evolved to improve the quality of information acquired via cultural transmission. Natural selection favored social learners who could evaluate potential models and copy the most successful among them. In order to improve the fidelity and comprehensiveness of such ranked-biased copying, social learners further evolved dispositions to sycophantically ingratiate themselves with their chosen models, so as to gain close proximity to, and prolonged interaction with, these models. Once common, these dispositions created, at the group level, distributions of deference that new entrants may adaptively exploit to decide who to begin copying. This generated a preference for models who seem generally "popular." Building on social exchange theories, we argue that a wider range of phenomena associated with prestige processes can more plausibly be explained by this simple theory than by others, and we test its predictions with data from throughout the social sciences. In addition, we distinguish carefully between dominance (force or force threat) and prestige (freely conferred deference).

Toward a theory of multilevel evolution: long-term information integration shapes the mutational landscape and enhances evolvability.

PubMed

Hogeweg, Paulien

2012-01-01

Most of evolutionary theory has abstracted away from how information is coded in the genome and how this information is transformed into traits on which selection takes place. While in the earliest stages of biological evolution, in the RNA world, the mapping from the genotype into function was largely predefined by the physical-chemical properties of the evolving entities (RNA replicators, e.g. from sequence to folded structure and catalytic sites), in present-day organisms, the mapping itself is the result of evolution. I will review results of several in silico evolutionary studies which examine the consequences of evolving the genetic coding, and the ways this information is transformed, while adapting to prevailing environments. Such multilevel evolution leads to long-term information integration. Through genome, network, and dynamical structuring, the occurrence and/or effect of random mutations becomes nonrandom, and facilitates rapid adaptation. This is what does happen in the in silico experiments. Is it also what did happen in biological evolution? I will discuss some data that suggest that it did. In any case, these results provide us with novel search images to tackle the wealth of biological data.

The evolutionary dynamics of haplodiploidy: Genome architecture and haploid viability.

PubMed

Blackmon, Heath; Hardy, Nate B; Ross, Laura

2015-11-01

Haplodiploid reproduction, in which males are haploid and females are diploid, is widespread among animals, yet we understand little about the forces responsible for its evolution. The current theory is that haplodiploidy has evolved through genetic conflicts, as it provides a transmission advantage to mothers. Male viability is thought to be a major limiting factor; diploid individuals tend to harbor many recessive lethal mutations. This theory predicts that the evolution of haplodiploidy is more likely in male heterogametic lineages with few chromosomes, as genes on the X chromosome are often expressed in a haploid environment, and the fewer the chromosome number, the greater the proportion of the total genome that is X-linked. We test this prediction with comparative phylogenetic analyses of mites, among which haplodiploidy has evolved repeatedly. We recover a negative correlation between chromosome number and haplodiploidy, find evidence that low chromosome number evolved prior to haplodiploidy, and that it is unlikely that diplodiploidy has reevolved from haplodiploid lineages of mites. These results are consistent with the predicted importance of haploid male viability. © 2015 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

The Motivational Interviewing Navigation Guide: A Process for Enhancing Teachers' Motivation to Adopt and Implement School-Based Interventions

ERIC Educational Resources Information Center

Frey, Andy J.; Lee, Jon; Small, Jason W.; Seeley, John R.; Walker, Hill M.; Feil, Edward G.

2013-01-01

There is a critical need to engage theory-driven research related to the deployment of mental health promotion initiatives and student outcomes. A growing body of research supporting the use of motivational interviewing and engagement strategies in education suggests that this approach may be promising to better understand mechanisms through which…

Career Counseling as an Environmental Support: Exploring Influences on Career Choice, Career Decision-Making Self-Efficacy, and Career Barriers

ERIC Educational Resources Information Center

Makela, Julia Panke

2011-01-01

This study was motivated by concerns regarding the difficult academic and career choices facing today's college students as they navigate higher education and encounter career barriers along their paths. Using Social Cognitive Career Theory (SCCT; Lent, Brown, & Hackett, 1994) as a primary framework, the study sought to understand the role that…

Knowledge: Creation, Organization and Use. ASIS '99: Proceedings of the American Society for Information Science (ASIS) Annual Meeting (62nd, Washington, DC, October 31-November 4, 1999). Volume 36.

ERIC Educational Resources Information Center

Woods, Larry, Ed.

The 1999 American Society for Information Science (ASIS) conference explored current knowledge creation, acquisition, navigation, correlation, retrieval, management, and dissemination practicalities and potentialities, their implementation and impact, and the theories behind the developments. Speakers reviewed processes, technologies, and tools,…

Students' Learning with the Connected Chemistry (CC1) Curriculum: Navigating the Complexities of the Particulate World

ERIC Educational Resources Information Center

Levy, Sharona T.; Wilensky, Uri

2009-01-01

The focus of this study is students' learning with a Connected Chemistry unit, CC1 (denotes Connected Chemistry, chapter 1), a computer-based environment for learning the topics of gas laws and kinetic molecular theory in chemistry (Levy and Wilensky 2009). An investigation was conducted into high-school students' learning with Connected…

The Career Development of Latina Women Achieving the Position of Public High School Principal

ERIC Educational Resources Information Center

Palacio, Consuelo A.

2013-01-01

For this qualitative study, I used the lens of the Social Cognitive Career Theory to investigate the lived experiences of Latina women navigating their career paths into the roles of public high school principals. Latina women are underrepresented and in some states they are not represented at all. Few Latina women have secured the position of…

"We Have to Be Really Careful with What We Say": Critical Discourses across Difference in Pre-Service Teacher Education

ERIC Educational Resources Information Center

Marom, Lilach

2017-01-01

In this article the author expresses a concern that teacher educators are sending teacher candidates ill-prepared into their classrooms to navigate diversity and to open controversial issues in their own classes. The author calls for the increased inclusion of critical theories in teacher education as an important move, especially when neoliberal…

Navigation Solution for a Multiple Satellite and Multiple Ground Architecture

DTIC Science & Technology

2014-09-14

Primer Vector Theory . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.2.6 The Traveling Salesman Problem . . . . . . . . . . . . . . . . . . 12...the Traveling Salesman problem [42]. It is framed as a nonlinear programming, complete combinatorial optimization where the orbital debris pieces relate...impulsive maneuvers and applies his findings to a Hohmann transfer with the addition of mid-course burns and wait times. 2.2.6 The Traveling Salesman

Navigating Windows into Past Human Minds: A Framework of Shifting Selves in Historical Perspective Taking

ERIC Educational Resources Information Center

Nilsen, Adam P.

2016-01-01

This article presents a framework for understanding historical perspective taking (HPT), the effort to use historical material to explore the internal states of past people. It addresses gaps in HPT research by (a) linking HPT to theories and research from the social science disciplines on perspective taking and the self and (b) proposing a way to…

Competing and Conflicting Identity Plotlines: Navigating Personal Narratives of Entering Teaching

ERIC Educational Resources Information Center

Rice, Mary

2011-01-01

This self-study explores the range of stories I tell about coming to teach, my perceptions of the various audiences as I engage in the telling of such stories, and the competing and conflicting plotlines entailed in the set of stories. Using positioning theory and narrative inquiry tools, I identify and unpack a canon of stories that have one of…

Disruptive innovation in academic medical centers: balancing accountable and academic care.

PubMed

Stein, Daniel; Chen, Christopher; Ackerly, D Clay

2015-05-01

Numerous academic medicine leaders have argued that academic referral centers must prepare for the growing importance of accountability-driven payment models by adopting population health initiatives. Although this shift has merit, execution of this strategy will prove significantly more problematic than most observers have appreciated. The authors describe how successful implementation of an accountable care health strategy within a referral academic medical center (AMC) requires navigating a critical tension: The academic referral business model, driven by tertiary-level care, is fundamentally in conflict with population health. Referral AMCs that create successful value-driven population health systems within their organizations will in effect disrupt their own existing tertiary care businesses. The theory of disruptive innovation suggests that balancing the push and pull of academic and accountable care within a single organization is achievable. However, it will require significant shifts in resource allocation and changes in management structure to enable AMCs to make the inherent difficult choices and trade-offs that will ensue. On the basis of the theories of disruptive innovation, the authors present recommendations for how academic health systems can successfully navigate these issues as they transition toward accountability-driven care.

Vision in the dimmest habitats on earth.

PubMed

Warrant, Eric

2004-10-01

A very large proportion of the world's animal species are active in dim light, either under the cover of night or in the depths of the sea. The worlds they see can be dim and extended, with light reaching the eyes from all directions at once, or they can be composed of bright point sources, like the multitudes of stars seen in a clear night sky or the rare sparks of bioluminescence that are visible in the deep sea. The eye designs of nocturnal and deep-sea animals have evolved in response to these two very different types of habitats, being optimised for maximum sensitivity to extended scenes, or to point sources, or to both. After describing the many visual adaptations that have evolved across the animal kingdom for maximising sensitivity to extended and point-source scenes, I then use case studies from the recent literature to show how these adaptations have endowed nocturnal animals with excellent vision. Nocturnal animals can see colour and negotiate dimly illuminated obstacles during flight. They can also navigate using learned terrestrial landmarks, the constellations of stars or the dim pattern of polarised light formed around the moon. The conclusion from these studies is clear: nocturnal habitats are just as rich in visual details as diurnal habitats are, and nocturnal animals have evolved visual systems capable of exploiting them. The same is certainly true of deep-sea animals, as future research will no doubt reveal.

Adolescent Perspectives on Patient-Provider Sexual Health Communication: A Qualitative Study.

PubMed

Hoopes, Andrea J; Benson, Samantha K; Howard, Heather B; Morrison, Diane M; Ko, Linda K; Shafii, Taraneh

2017-10-01

Adolescents in the United States are disproportionately affected by sexually transmitted infections and unintended pregnancy. Adolescent-centered health services may reduce barriers to health care; yet, limited research has focused on adolescents' own perspectives on patient-provider communication during a sexual health visit. Twenty-four adolescents (14-19 years old) seeking care in a public health clinic in Washington State participated in one-on-one qualitative interviews. Interviews explored participants' past experiences with medical providers and their preferences regarding provider characteristics and communication strategies. Interviews revealed that (1) individual patient dynamics and (2) patient-provider interaction dynamics shape the experience during a sexual health visit. Individual patient dynamics included evolving level of maturity, autonomy, and sexual experience. Patient-provider interaction dynamics were shaped by adolescents' perceptions of providers as sources of health information who distribute valued sexual health supplies like contraception and condoms. Participant concerns about provider judgment, power differential, and lack of confidentiality also emerged as important themes. Adolescents demonstrate diverse and evolving needs for sexual health care and interactions with clinicians as they navigate sexual and emotional development.

What insects can tell us about the origins of consciousness

PubMed Central

Barron, Andrew B.; Klein, Colin

2016-01-01

How, why, and when consciousness evolved remain hotly debated topics. Addressing these issues requires considering the distribution of consciousness across the animal phylogenetic tree. Here we propose that at least one invertebrate clade, the insects, has a capacity for the most basic aspect of consciousness: subjective experience. In vertebrates the capacity for subjective experience is supported by integrated structures in the midbrain that create a neural simulation of the state of the mobile animal in space. This integrated and egocentric representation of the world from the animal’s perspective is sufficient for subjective experience. Structures in the insect brain perform analogous functions. Therefore, we argue the insect brain also supports a capacity for subjective experience. In both vertebrates and insects this form of behavioral control system evolved as an efficient solution to basic problems of sensory reafference and true navigation. The brain structures that support subjective experience in vertebrates and insects are very different from each other, but in both cases they are basal to each clade. Hence we propose the origins of subjective experience can be traced to the Cambrian. PMID:27091981

Experimental evolution of insect immune memory versus pathogen resistance.

PubMed

Khan, Imroze; Prakash, Arun; Agashe, Deepa

2017-12-20

Under strong pathogen pressure, insects often evolve resistance to infection. Many insects are also protected via immune memory (immune priming), whereby sublethal exposure to a pathogen enhances survival after secondary infection. Theory predicts that immune memory should evolve when the pathogen is highly virulent, or when pathogen exposure is relatively rare. However, there are no empirical tests of these hypotheses, and the adaptive benefits of immune memory relative to direct resistance against a pathogen are poorly understood. To determine the selective pressures and ecological conditions that shape immune evolution, we imposed strong pathogen selection on flour beetle ( Tribolium castaneum ) populations, infecting them with Bacillus thuringiensis (Bt) for 11 generations. Populations injected first with heat-killed and then live Bt evolved high basal resistance against multiple Bt strains. By contrast, populations injected only with a high dose of live Bt evolved a less effective but strain-specific priming response. Control populations injected with heat-killed Bt did not evolve priming; and in the ancestor, priming was effective only against a low Bt dose. Intriguingly, one replicate population first evolved priming and subsequently evolved basal resistance, suggesting the potential for dynamic evolution of different immune strategies. Our work is the first report showing that pathogens can select for rapid modulation of insect priming ability, allowing hosts to evolve divergent immune strategies (generalized resistance versus specific immune memory) with potentially distinct mechanisms. © 2017 The Author(s).

Digital correlation detector for low-cost Omega navigation

NASA Technical Reports Server (NTRS)

Chamberlin, K. A.

1976-01-01

Techniques to lower the cost of using the Omega global navigation network with phase-locked loops (PLL) were developed. The technique that was accepted as being "optimal" is called the memory-aided phase-locked loop (MAPLL) since it allows operation on all eight Omega time slots with one PLL through the implementation of a random access memory. The receiver front-end and the signals that it transmits to the PLL were first described. A brief statistical analysis of these signals was then made to allow a rough comparison between the front-end presented in this work and a commercially available front-end to be made. The hardware and theory of application of the MAPLL were described, ending with an analysis of data taken with the MAPLL. Some conclusions and recommendations were also given.

A Short Tutorial on Inertial Navigation System and Global Positioning System Integration

NASA Technical Reports Server (NTRS)

Smalling, Kyle M.; Eure, Kenneth W.

2015-01-01

The purpose of this document is to describe a simple method of integrating Inertial Navigation System (INS) information with Global Positioning System (GPS) information for an improved estimate of vehicle attitude and position. A simple two dimensional (2D) case is considered. The attitude estimates are derived from sensor data and used in the estimation of vehicle position and velocity through dead reckoning within the INS. The INS estimates are updated with GPS estimates using a Kalman filter. This tutorial is intended for the novice user with a focus on bringing the reader from raw sensor measurements to an integrated position and attitude estimate. An application is given using a remotely controlled ground vehicle operating in assumed 2D environment. The theory is developed first followed by an illustrative example.

Transitions theory: a trajectory of theoretical development in nursing.

PubMed

Im, Eun-Ok

2011-01-01

There have been very few investigations into how any single nursing theory has actually evolved historically. In this paper, a trajectory of theoretical development in nursing is explored through reviewing the theoretical development of a single nursing theory-transitions theory. The literature related to transitions theory was searched and retrieved using multiple databases. Ninety-nine papers were analyzed according to type of theory, populations of interest, sources of theorizing, and theoretical methods. Transitions theory originated in research but was initially borrowed. It also arose in research with immigrants and from national and international collaborative research efforts. A product of mentoring, transitions theory is used widely in nursing education, research, and practice. Diverse thoughts related to transitions theory coexist. For future theoretical development in nursing, we need to remain open to new ideas and continue to engage in multiple collaborative efforts. Copyright © 2011 Elsevier Inc. All rights reserved.

Understanding the process of patient satisfaction with nurse-led chronic disease management in general practice.

PubMed

Mahomed, Rosemary; St John, Winsome; Patterson, Elizabeth

2012-11-01

  To investigate the process of patient satisfaction with nurse-led chronic disease management in Australian general practice.   Nurses working in the primary care context of general practice, referred to as practice nurses, are expanding their role in chronic disease management; this is relatively new to Australia. Therefore, determining patient satisfaction with this trend is pragmatically and ethically important. However, the concept of patient satisfaction is not well understood particularly in relation to care provided by practice nurses.   A grounded theory study underpinned by a relativist ontological position and a relativist epistemology.   Grounded theory was used to develop a theory from data collected through in-depth interviews with 38 participants between November 2007-April 2009. Participants were drawn from a larger project that trialled a practice nurse-led, collaborative model of chronic disease management in three Australian general practices. Theoretical sampling, data collection, and analysis were conducted concurrently consistent with grounded theory methods.   Patients undergo a cyclical process of Navigating Care involving three stages, Determining Care Needs, Forming Relationship, and Having Confidence. The latter two processes are inter-related and a feedback loop from them informs subsequent cycles of Determining Care Needs. If any of these steps fails to develop adequately, patients are likely to opt out of nurse-led care.   Navigating Care explains how and why time, communication, continuity, and trust in general practitioners and nurses are important to patient satisfaction. It can be used in identifying suitable patients for practice nurse-led care and to inform the practice and organization of practice nurse-led care to enhance patient satisfaction. © 2012 Blackwell Publishing Ltd.

State of the art of sonic boom modeling

NASA Astrophysics Data System (ADS)

Plotkin, Kenneth J.

2002-01-01

Based on fundamental theory developed through the 1950s and 1960s, sonic boom modeling has evolved into practical tools. Over the past decade, there have been requirements for design tools for an advanced supersonic transport, and for tools for environmental assessment of various military and aerospace activities. This has resulted in a number of advances in the understanding of the physics of sonic booms, including shock wave rise times, propagation through turbulence, and blending sonic boom theory with modern computational fluid dynamics (CFD) aerodynamic design methods. This article reviews the early fundamental theory, recent advances in theory, and the application of these advances to practical models.

State of the art of sonic boom modeling.

PubMed

Plotkin, Kenneth J

2002-01-01

Based on fundamental theory developed through the 1950s and 1960s, sonic boom modeling has evolved into practical tools. Over the past decade, there have been requirements for design tools for an advanced supersonic transport, and for tools for environmental assessment of various military and aerospace activities. This has resulted in a number of advances in the understanding of the physics of sonic booms, including shock wave rise times, propagation through turbulence, and blending sonic boom theory with modern computational fluid dynamics (CFD) aerodynamic design methods. This article reviews the early fundamental theory, recent advances in theory, and the application of these advances to practical models.

Perinatal sadness among Shuar women: support for an evolutionary theory of psychic pain.

PubMed

Hagen, Edward H; Barrett, H Clark

2007-03-01

Psychiatry faces an internal contradiction in that it regards mild sadness and low mood as normal emotions, yet when these emotions are directed toward a new infant, it regards them as abnormal. We apply parental investment theory, a widely used framework from evolutionary biology, to maternal perinatal emotions, arguing that negative emotions directed toward a new infant could serve an important evolved function. If so, then under some definitions of psychiatric disorder, these emotions are not disorders. We investigate the applicability of parental investment theory to maternal postpartum emotions among Shuar mothers. Shuar mothers' conceptions of perinatal sadness closely match predictions of parental investment theory.

Integrating cortico-limbic-basal ganglia architectures for learning model-based and model-free navigation strategies

PubMed Central

Khamassi, Mehdi; Humphries, Mark D.

2012-01-01

Behavior in spatial navigation is often organized into map-based (place-driven) vs. map-free (cue-driven) strategies; behavior in operant conditioning research is often organized into goal-directed vs. habitual strategies. Here we attempt to unify the two. We review one powerful theory for distinct forms of learning during instrumental conditioning, namely model-based (maintaining a representation of the world) and model-free (reacting to immediate stimuli) learning algorithms. We extend these lines of argument to propose an alternative taxonomy for spatial navigation, showing how various previously identified strategies can be distinguished as “model-based” or “model-free” depending on the usage of information and not on the type of information (e.g., cue vs. place). We argue that identifying “model-free” learning with dorsolateral striatum and “model-based” learning with dorsomedial striatum could reconcile numerous conflicting results in the spatial navigation literature. From this perspective, we further propose that the ventral striatum plays key roles in the model-building process. We propose that the core of the ventral striatum is positioned to learn the probability of action selection for every transition between states of the world. We further review suggestions that the ventral striatal core and shell are positioned to act as “critics” contributing to the computation of a reward prediction error for model-free and model-based systems, respectively. PMID:23205006

Exploring the Future of Security in the Caribbean: a Regional Security Partnership?

DTIC Science & Technology

2007-12-14

by these organizations and their members. 25 CHAPTER 2 LITERATURE REVIEW Psychologist Abraham Maslow posited that safety [read security] is one...addressing the security needs of the Caribbean Basin and the United States? Of necessity , there are several secondary questions which must be...development of models/ theories of security. These theories of security abound, and have evolved as the international arena has changed. Realists, idealists and

Multiple rod–cone and cone–rod photoreceptor transmutations in snakes: Evidence from visual opsin gene expression

USGS Publications Warehouse

Simoe, Bruno F; Sampaio, Filipa L.; Loew, Ellis R.; Sanders, Kate L.; Fisher, Robert N.; Hart, Nathan S.; Hunt, David M.; Partridge, Julian C.; Gower, David J.

2016-01-01

In 1934, Gordon Walls forwarded his radical theory of retinal photoreceptor ‘transmutation’. This proposed that rods and cones used for scotopic and photopic vision, respectively, were not fixed but could evolve into each other via a series of morphologically distinguishable intermediates. Walls' prime evidence came from series of diurnal and nocturnal geckos and snakes that appeared to have pure-cone or pure-rod retinas (in forms that Walls believed evolved from ancestors with the reverse complement) or which possessed intermediate photoreceptor cells. Walls was limited in testing his theory because the precise identity of visual pigments present in photoreceptors was then unknown. Subsequent molecular research has hitherto neglected this topic but presents new opportunities. We identify three visual opsin genes, rh1, sws1 and lws, in retinal mRNA of an ecologically and taxonomically diverse sample of snakes central to Walls' theory. We conclude that photoreceptors with superficially rod- or cone-like morphology are not limited to containing scotopic or photopic opsins, respectively. Walls' theory is essentially correct, and more research is needed to identify the patterns, processes and functional implications of transmutation. Future research will help to clarify the fundamental properties and physiology of photoreceptors adapted to function in different light levels.

Multiple rod–cone and cone–rod photoreceptor transmutations in snakes: evidence from visual opsin gene expression

PubMed Central

Sampaio, Filipa L.; Loew, Ellis R.; Sanders, Kate L.; Fisher, Robert N.; Hart, Nathan S.; Hunt, David M.; Partridge, Julian C.

2016-01-01

In 1934, Gordon Walls forwarded his radical theory of retinal photoreceptor ‘transmutation’. This proposed that rods and cones used for scotopic and photopic vision, respectively, were not fixed but could evolve into each other via a series of morphologically distinguishable intermediates. Walls' prime evidence came from series of diurnal and nocturnal geckos and snakes that appeared to have pure-cone or pure-rod retinas (in forms that Walls believed evolved from ancestors with the reverse complement) or which possessed intermediate photoreceptor cells. Walls was limited in testing his theory because the precise identity of visual pigments present in photoreceptors was then unknown. Subsequent molecular research has hitherto neglected this topic but presents new opportunities. We identify three visual opsin genes, rh1, sws1 and lws, in retinal mRNA of an ecologically and taxonomically diverse sample of snakes central to Walls' theory. We conclude that photoreceptors with superficially rod- or cone-like morphology are not limited to containing scotopic or photopic opsins, respectively. Walls' theory is essentially correct, and more research is needed to identify the patterns, processes and functional implications of transmutation. Future research will help to clarify the fundamental properties and physiology of photoreceptors adapted to function in different light levels. PMID:26817768

Multiple rod-cone and cone-rod photoreceptor transmutations in snakes: evidence from visual opsin gene expression.

PubMed

Simões, Bruno F; Sampaio, Filipa L; Loew, Ellis R; Sanders, Kate L; Fisher, Robert N; Hart, Nathan S; Hunt, David M; Partridge, Julian C; Gower, David J

2016-01-27

In 1934, Gordon Walls forwarded his radical theory of retinal photoreceptor 'transmutation'. This proposed that rods and cones used for scotopic and photopic vision, respectively, were not fixed but could evolve into each other via a series of morphologically distinguishable intermediates. Walls' prime evidence came from series of diurnal and nocturnal geckos and snakes that appeared to have pure-cone or pure-rod retinas (in forms that Walls believed evolved from ancestors with the reverse complement) or which possessed intermediate photoreceptor cells. Walls was limited in testing his theory because the precise identity of visual pigments present in photoreceptors was then unknown. Subsequent molecular research has hitherto neglected this topic but presents new opportunities. We identify three visual opsin genes, rh1, sws1 and lws, in retinal mRNA of an ecologically and taxonomically diverse sample of snakes central to Walls' theory. We conclude that photoreceptors with superficially rod- or cone-like morphology are not limited to containing scotopic or photopic opsins, respectively. Walls' theory is essentially correct, and more research is needed to identify the patterns, processes and functional implications of transmutation. Future research will help to clarify the fundamental properties and physiology of photoreceptors adapted to function in different light levels. © 2016 The Author(s).

The Vitamin D–Folate Hypothesis as an Evolutionary Model for Skin Pigmentation: An Update and Integration of Current Ideas

PubMed Central

Lucock, Mark; Veysey, Martin; Beckett, Emma

2018-01-01

Vitamin D is unique in being generated in our skin following ultraviolet radiation (UVR) exposure. Ongoing research into vitamin D must therefore always consider the influence of UVR on vitamin D processes. The close relationship between vitamin D and UVR forms the basis of the “vitamin D–folate hypothesis”, a popular theory for why human skin colour has evolved as an apparent adaption to UVR environments. Vitamin D and folate have disparate sensitivities to UVR; whilst vitamin D may be synthesised following UVR exposure, folate may be degraded. The vitamin D–folate hypothesis proposes that skin pigmentation has evolved as a balancing mechanism, maintaining levels of these vitamins. There are several alternative theories that counter the vitamin D–folate hypothesis. However, there is significant overlap between these theories and the now known actions of vitamin D and folate in the skin. The focus of this review is to present an update on the vitamin D–folate hypothesis by integrating these current theories and discussing new evidence that supports associations between vitamin D and folate genetics, UVR, and skin pigmentation. In light of recent human migrations and seasonality in disease, the need for ongoing research into potential UVR-responsive processes within the body is also discussed. PMID:29710859

A slowly evolving host moves first in symbiotic interactions

NASA Astrophysics Data System (ADS)

Damore, James; Gore, Jeff

2011-03-01

Symbiotic relationships, both parasitic and mutualistic, are ubiquitous in nature. Understanding how these symbioses evolve, from bacteria and their phages to humans and our gut microflora, is crucial in understanding how life operates. Often, symbioses consist of a slowly evolving host species with each host only interacting with its own sub-population of symbionts. The Red Queen hypothesis describes coevolutionary relationships as constant arms races with each species rushing to evolve an advantage over the other, suggesting that faster evolution is favored. Here, we use a simple game theoretic model of host- symbiont coevolution that includes population structure to show that if the symbionts evolve much faster than the host, the equilibrium distribution is the same as it would be if it were a sequential game where the host moves first against its symbionts. For the slowly evolving host, this will prove to be advantageous in mutualisms and a handicap in antagonisms. The model allows for symbiont adaptation to its host, a result that is robust to changes in the parameters and generalizes to continuous and multiplayer games. Our findings provide insight into a wide range of symbiotic phenomena and help to unify the field of coevolutionary theory.

Toward the Language-Ready Brain: Biological Evolution and Primate Comparisons.

PubMed

Arbib, Michael A

2017-02-01

The approach to language evolution suggested here focuses on three questions: How did the human brain evolve so that humans can develop, use, and acquire languages? How can the evolutionary quest be informed by studying brain, behavior, and social interaction in monkeys, apes, and humans? How can computational modeling advance these studies? I hypothesize that the brain is language ready in that the earliest humans had protolanguages but not languages (i.e., communication systems endowed with rich and open-ended lexicons and grammars supporting a compositional semantics), and that it took cultural evolution to yield societies (a cultural constructed niche) in which language-ready brains could become language-using brains. The mirror system hypothesis is a well-developed example of this approach, but I offer it here not as a closed theory but as an evolving framework for the development and analysis of conflicting subhypotheses in the hope of their eventual integration. I also stress that computational modeling helps us understand the evolving role of mirror neurons, not in and of themselves, but only in their interaction with systems "beyond the mirror." Because a theory of evolution needs a clear characterization of what it is that evolved, I also outline ideas for research in neurolinguistics to complement studies of the evolution of the language-ready brain. A clear challenge is to go beyond models of speech comprehension to include sign language and models of production, and to link language to visuomotor interaction with the physical and social world.

Dynamic wormhole solutions in Einstein-Cartan gravity

NASA Astrophysics Data System (ADS)

Mehdizadeh, Mohammad Reza; Ziaie, Amir Hadi

2017-12-01

In the present work, we investigate evolving wormhole configurations described by a constant redshift function in Einstein-Cartan theory. The matter content consists of a Weyssenhoff fluid along with an anisotropic matter which together generalize the anisotropic energy momentum tensor in general relativity in order to include the effects of intrinsic angular momentum (spin) of particles. Using a generalized Friedmann-Robertson-Walker spacetime, we derive analytical evolving wormhole geometries by assuming a particular equation of state for energy density and pressure profiles. We introduce exact asymptotically flat and anti-de Sitter spacetimes that admit traversable wormholes and respect energy conditions throughout the spacetime. The rate of expansion of these evolving wormholes is determined only by the Friedmann equation in the presence of spin effects.

Combined Global Navigation Satellite Systems in the Space Service Volume

NASA Technical Reports Server (NTRS)

Force, Dale A.; Miller, James J.

2015-01-01

Besides providing position, navigation, and timing (PNT) services to traditional terrestrial and airborne users, GPS is also being increasingly used as a tool to enable precision orbit determination, precise time synchronization, real-time spacecraft navigation, and three-axis attitude control of Earth orbiting satellites. With additional Global Navigation Satellite System (GNSS) constellations being replenished and coming into service (GLONASS, Beidou, and Galileo), it will become possible to benefit from greater signal availability and robustness by using evolving multi-constellation receivers. The paper, "GPS in the Space Service Volume," presented at the ION GNSS 19th International Technical Meeting in 2006 (Ref. 1), defined the Space Service Volume, and analyzed the performance of GPS out to seventy thousand kilometers. This paper will report a similar analysis of the signal coverage of GPS in the space domain; however, the analyses will also consider signal coverage from each of the additional GNSS constellations noted earlier to specifically demonstrate the expected benefits to be derived from using GPS in conjunction with other foreign systems. The Space Service Volume is formally defined as the volume of space between three thousand kilometers altitude and geosynchronous altitude circa 36,000 km, as compared with the Terrestrial Service Volume between 3,000 km and the surface of the Earth. In the Terrestrial Service Volume, GNSS performance is the same as on or near the Earth's surface due to satellite vehicle availability and geometry similarities. The core GPS system has thereby established signal requirements for the Space Service Volume as part of technical Capability Development Documentation (CDD) that specifies system performance. Besides the technical discussion, we also present diplomatic efforts to extend the GPS Space Service Volume concept to other PNT service providers in an effort to assure that all space users will benefit from the enhanced interoperability of GNSS services in the space domain. A separate paper presented at the conference covers the individual GNSS performance parameters for respective Space Service Volumes.

Establishing a Near Term Lunar Farside Gravity Model via Inexpensive Add-on Navigation Payload

NASA Technical Reports Server (NTRS)

Folta, David; Mesarch, Michael; Miller, Ronald; Bell, David; Jedrey, Tom; Butman, Stanley; Asmar, Sami

2007-01-01

The Space Communications and Navigation, Constellation Integration Project (SCIP) is tasked with defining, developing, deploying and operating an evolving multi-decade communications and navigation (C/N) infrastructure including services and subsystems that will support both robotic and human exploration activities at the Moon. This paper discusses an early far side gravitational mapping service and related telecom subsystem that uses an existing spacecraft (WIND) and the Lunar Reconnaissance Orbiter (LRO) to collect data that would address several needs of the SCIP. An important aspect of such an endeavor is to vastly improve the current lunar gravity model while demonstrating the navigation and stationkeeping of a relay spacecraft. We describe a gravity data acquisition activity and the trajectory design of the relay orbit in an Earth-Moon L2 co-linear libration orbit. Several phases of the transfer from an Earth-Sun to the Earth-Moon region are discussed along with transfers within the Earth-Moon system. We describe a proposed, but not integrated, add-on to LRO scheduled to be launched in October of 2008. LRO provided a real host spacecraft against which we designed the science payload and mission activities. From a strategic standpoint, LRO was a very exciting first flight opportunity for gravity science data collection. Gravity Science data collection requires the use of one or more low altitude lunar polar orbiters. Variations in the lunar gravity field will cause measurable variations in the orbit of a low altitude lunar orbiter. The primary means to capture these induced motions is to monitor the Doppler shift of a radio signal to or from the low altitude spacecraft, given that the signal is referenced to a stable frequency reference. For the lunar far side, a secondary orbiting radio signal platform is required. We provide an in-depth look at link margins, trajectory design, and hardware implications. Our approach posed minimum risk to a host mission while maintaining a very low implementation and operations cost.

Categorizing words through semantic memory navigation

NASA Astrophysics Data System (ADS)

Borge-Holthoefer, J.; Arenas, A.

2010-03-01

Semantic memory is the cognitive system devoted to storage and retrieval of conceptual knowledge. Empirical data indicate that semantic memory is organized in a network structure. Everyday experience shows that word search and retrieval processes provide fluent and coherent speech, i.e. are efficient. This implies either that semantic memory encodes, besides thousands of words, different kind of links for different relationships (introducing greater complexity and storage costs), or that the structure evolves facilitating the differentiation between long-lasting semantic relations from incidental, phenomenological ones. Assuming the latter possibility, we explore a mechanism to disentangle the underlying semantic backbone which comprises conceptual structure (extraction of categorical relations between pairs of words), from the rest of information present in the structure. To this end, we first present and characterize an empirical data set modeled as a network, then we simulate a stochastic cognitive navigation on this topology. We schematize this latter process as uncorrelated random walks from node to node, which converge to a feature vectors network. By doing so we both introduce a novel mechanism for information retrieval, and point at the problem of category formation in close connection to linguistic and non-linguistic experience.

Relaxing the cosmological constant: a proof of concept

NASA Astrophysics Data System (ADS)

Alberte, Lasma; Creminelli, Paolo; Khmelnitsky, Andrei; Pirtskhalava, David; Trincherini, Enrico

2016-12-01

We propose a technically natural scenario whereby an initially large cosmological constant (c.c.) is relaxed down to the observed value due to the dynamics of a scalar evolving on a very shallow potential. The model crucially relies on a sector that violates the null energy condition (NEC) and gets activated only when the Hubble rate becomes sufficiently small — of the order of the present one. As a result of NEC violation, this low-energy universe evolves into inflation, followed by reheating and the standard Big Bang cosmology. The symmetries of the theory force the c.c. to be the same before and after the NEC-violating phase, so that a late-time observer sees an effective c.c. of the correct magnitude. Importantly, our model allows neither for eternal inflation nor for a set of possible values of dark energy, the latter fixed by the parameters of the theory.

Rates of speciation and morphological evolution are correlated across the largest vertebrate radiation.

PubMed

Rabosky, Daniel L; Santini, Francesco; Eastman, Jonathan; Smith, Stephen A; Sidlauskas, Brian; Chang, Jonathan; Alfaro, Michael E

2013-01-01

Several evolutionary theories predict that rates of morphological change should be positively associated with the rate at which new species arise. For example, the theory of punctuated equilibrium proposes that phenotypic change typically occurs in rapid bursts associated with speciation events. However, recent phylogenetic studies have found little evidence linking these processes in nature. Here we demonstrate that rates of species diversification are highly correlated with the rate of body size evolution across the 30,000+ living species of ray-finned fishes that comprise the majority of vertebrate biological diversity. This coupling is a general feature of fish evolution and transcends vast differences in ecology and body-plan organization. Our results may reflect a widespread speciational mode of character change in living fishes. Alternatively, these findings are consistent with the hypothesis that phenotypic 'evolvability'-the capacity of organisms to evolve-shapes the dynamics of speciation through time at the largest phylogenetic scales.

The maintenance of single-locus polymorphism. IV. Models with mutation from existing alleles.

PubMed

Spencer, H G; Marks, R W

1992-01-01

The ability of viability selection to maintain allelic polymorphism is investigated using a constructionist approach. In extensions to the models we have previously proposed, a population is bombarded with a series of mutations whose fitnesses in conjunction with other alleles are functions of the corresponding fitnesses with a particular allele, the parent allele, already in the population. Allele frequencies are iterated simultaneously, thus allowing alleles to be driven to extinction by selection. Such models allow very high levels of polymorphism to evolve: up to 38 alleles in one case. Alleles that are lethal as homozygotes can evolve to surprisingly high frequencies. The joint evolution of allele frequencies and viabilities highlights the necessity to consider more than the current morphology of a population. Comparisons are made with the neutral theory of evolution and it is suggested that failure to reject neutrality using the Ewens-Watterson test cannot be regarded as evidence for the neutral theory.

The organization and control of an evolving interdependent population

PubMed Central

Vural, Dervis C.; Isakov, Alexander; Mahadevan, L.

2015-01-01

Starting with Darwin, biologists have asked how populations evolve from a low fitness state that is evolutionarily stable to a high fitness state that is not. Specifically of interest is the emergence of cooperation and multicellularity where the fitness of individuals often appears in conflict with that of the population. Theories of social evolution and evolutionary game theory have produced a number of fruitful results employing two-state two-body frameworks. In this study, we depart from this tradition and instead consider a multi-player, multi-state evolutionary game, in which the fitness of an agent is determined by its relationship to an arbitrary number of other agents. We show that populations organize themselves in one of four distinct phases of interdependence depending on one parameter, selection strength. Some of these phases involve the formation of specialized large-scale structures. We then describe how the evolution of independence can be manipulated through various external perturbations. PMID:26040593

2010 MULTIPHOTON PROCESSES GORDON RESEARCH CONFERENCE, JUNE 6-11, 2010, TILTON, NH

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

Mette Gaarde

2010-06-11

The Gordon Research Conference on Multiphoton Processes will be held for the 15th time in 2010. The meeting continues to evolve as it embraces both the rapid technological and intellectual growth in the field as well as the multi-disciplinary expertise of the participants. This time the sessions will focus on: (1) Ultrafast coherent control; (2) Free-electron laser experiments and theory; (3) Generation of harmonics and attosecond pulses; (4) Ultrafast imaging; (5) Applications of very high intensity laser fields; (6) Strong-field processes in molecules and solids; (7) Attosecond science; and (8) Controlling light. The scientific program will blur traditional disciplinary boundariesmore » as the presenters and discussion leaders involve chemists, physicists, and optical engineers, representing both experiment and theory. The broad range of expertise and different perspectives of attendees should provide a stimulating and unique environment for solving problems and developing new ideas in this rapidly evolving field.« less

"Genetically Engineered" Nanoelectronics

NASA Technical Reports Server (NTRS)

Klimeck, Gerhard; Salazar-Lazaro, Carlos H.; Stoica, Adrian; Cwik, Thomas

2000-01-01

The quantum mechanical functionality of nanoelectronic devices such as resonant tunneling diodes (RTDs), quantum well infrared-photodetectors (QWIPs), quantum well lasers, and heterostructure field effect transistors (HFETs) is enabled by material variations on an atomic scale. The design and optimization of such devices requires a fundamental understanding of electron transport in such dimensions. The Nanoelectronic Modeling Tool (NEMO) is a general-purpose quantum device design and analysis tool based on a fundamental non-equilibrium electron transport theory. NEW was combined with a parallelized genetic algorithm package (PGAPACK) to evolve structural and material parameters to match a desired set of experimental data. A numerical experiment that evolves structural variations such as layer widths and doping concentrations is performed to analyze an experimental current voltage characteristic. The genetic algorithm is found to drive the NEMO simulation parameters close to the experimentally prescribed layer thicknesses and doping profiles. With such a quantitative agreement between theory and experiment design synthesis can be performed.

REVIEWS OF TOPICAL PROBLEMS: Experimental tests of general relativity: recent progress and future directions

NASA Astrophysics Data System (ADS)

Turyshev, S. G.

2009-01-01

Einstein's general theory of relativity is the standard theory of gravity, especially where the needs of astronomy, astrophysics, cosmology, and fundamental physics are concerned. As such, this theory is used for many practical purposes involving spacecraft navigation, geodesy, and time transfer. We review the foundations of general relativity, discuss recent progress in tests of relativistic gravity, and present motivations for the new generation of high-accuracy tests of new physics beyond general relativity. Space-based experiments in fundamental physics are presently capable of uniquely addressing important questions related to the fundamental laws of nature. We discuss the advances in our understanding of fundamental physics that are anticipated in the near future and evaluate the discovery potential of a number of recently proposed space-based gravitational experiments.

North error estimation based on solar elevation errors in the third step of sky-polarimetric Viking navigation.

PubMed

Száz, Dénes; Farkas, Alexandra; Barta, András; Kretzer, Balázs; Egri, Ádám; Horváth, Gábor

2016-07-01

The theory of sky-polarimetric Viking navigation has been widely accepted for decades without any information about the accuracy of this method. Previously, we have measured the accuracy of the first and second steps of this navigation method in psychophysical laboratory and planetarium experiments. Now, we have tested the accuracy of the third step in a planetarium experiment, assuming that the first and second steps are errorless. Using the fists of their outstretched arms, 10 test persons had to estimate the elevation angles (measured in numbers of fists and fingers) of black dots (representing the position of the occluded Sun) projected onto the planetarium dome. The test persons performed 2400 elevation estimations, 48% of which were more accurate than ±1°. We selected three test persons with the (i) largest and (ii) smallest elevation errors and (iii) highest standard deviation of the elevation error. From the errors of these three persons, we calculated their error function, from which the North errors (the angles with which they deviated from the geographical North) were determined for summer solstice and spring equinox, two specific dates of the Viking sailing period. The range of possible North errors Δ ω N was the lowest and highest at low and high solar elevations, respectively. At high elevations, the maximal Δ ω N was 35.6° and 73.7° at summer solstice and 23.8° and 43.9° at spring equinox for the best and worst test person (navigator), respectively. Thus, the best navigator was twice as good as the worst one. At solstice and equinox, high elevations occur the most frequently during the day, thus high North errors could occur more frequently than expected before. According to our findings, the ideal periods for sky-polarimetric Viking navigation are immediately after sunrise and before sunset, because the North errors are the lowest at low solar elevations.

Maintaining a Cognitive Map in Darkness: The Need to Fuse Boundary Knowledge with Path Integration

PubMed Central

Cheung, Allen; Ball, David; Milford, Michael; Wyeth, Gordon; Wiles, Janet

2012-01-01

Spatial navigation requires the processing of complex, disparate and often ambiguous sensory data. The neurocomputations underpinning this vital ability remain poorly understood. Controversy remains as to whether multimodal sensory information must be combined into a unified representation, consistent with Tolman's “cognitive map”, or whether differential activation of independent navigation modules suffice to explain observed navigation behaviour. Here we demonstrate that key neural correlates of spatial navigation in darkness cannot be explained if the path integration system acted independently of boundary (landmark) information. In vivo recordings demonstrate that the rodent head direction (HD) system becomes unstable within three minutes without vision. In contrast, rodents maintain stable place fields and grid fields for over half an hour without vision. Using a simple HD error model, we show analytically that idiothetic path integration (iPI) alone cannot be used to maintain any stable place representation beyond two to three minutes. We then use a measure of place stability based on information theoretic principles to prove that featureless boundaries alone cannot be used to improve localization above chance level. Having shown that neither iPI nor boundaries alone are sufficient, we then address the question of whether their combination is sufficient and – we conjecture – necessary to maintain place stability for prolonged periods without vision. We addressed this question in simulations and robot experiments using a navigation model comprising of a particle filter and boundary map. The model replicates published experimental results on place field and grid field stability without vision, and makes testable predictions including place field splitting and grid field rescaling if the true arena geometry differs from the acquired boundary map. We discuss our findings in light of current theories of animal navigation and neuronal computation, and elaborate on their implications and significance for the design, analysis and interpretation of experiments. PMID:22916006

North error estimation based on solar elevation errors in the third step of sky-polarimetric Viking navigation

PubMed Central

Száz, Dénes; Farkas, Alexandra; Barta, András; Kretzer, Balázs; Egri, Ádám

2016-01-01

The theory of sky-polarimetric Viking navigation has been widely accepted for decades without any information about the accuracy of this method. Previously, we have measured the accuracy of the first and second steps of this navigation method in psychophysical laboratory and planetarium experiments. Now, we have tested the accuracy of the third step in a planetarium experiment, assuming that the first and second steps are errorless. Using the fists of their outstretched arms, 10 test persons had to estimate the elevation angles (measured in numbers of fists and fingers) of black dots (representing the position of the occluded Sun) projected onto the planetarium dome. The test persons performed 2400 elevation estimations, 48% of which were more accurate than ±1°. We selected three test persons with the (i) largest and (ii) smallest elevation errors and (iii) highest standard deviation of the elevation error. From the errors of these three persons, we calculated their error function, from which the North errors (the angles with which they deviated from the geographical North) were determined for summer solstice and spring equinox, two specific dates of the Viking sailing period. The range of possible North errors ΔωN was the lowest and highest at low and high solar elevations, respectively. At high elevations, the maximal ΔωN was 35.6° and 73.7° at summer solstice and 23.8° and 43.9° at spring equinox for the best and worst test person (navigator), respectively. Thus, the best navigator was twice as good as the worst one. At solstice and equinox, high elevations occur the most frequently during the day, thus high North errors could occur more frequently than expected before. According to our findings, the ideal periods for sky-polarimetric Viking navigation are immediately after sunrise and before sunset, because the North errors are the lowest at low solar elevations. PMID:27493566

From cues to signals: evolution of interspecific communication via aposematism and mimicry in a predator-prey system.

PubMed

Lehmann, Kenna D S; Goldman, Brian W; Dworkin, Ian; Bryson, David M; Wagner, Aaron P

2014-01-01

Current theory suggests that many signaling systems evolved from preexisting cues. In aposematic systems, prey warning signals benefit both predator and prey. When the signal is highly beneficial, a third species often evolves to mimic the toxic species, exploiting the signaling system for its own protection. We investigated the evolutionary dynamics of predator cue utilization and prey signaling in a digital predator-prey system in which prey could evolve to alter their appearance to mimic poison-free or poisonous prey. In predators, we observed rapid evolution of cue recognition (i.e. active behavioral responses) when presented with sufficiently poisonous prey. In addition, active signaling (i.e. mimicry) evolved in prey under all conditions that led to cue utilization. Thus we show that despite imperfect and dishonest signaling, given a high cost of consuming poisonous prey, complex systems of interspecific communication can evolve via predator cue recognition and prey signal manipulation. This provides evidence supporting hypotheses that cues may serve as stepping-stones in the evolution of more advanced communication and signaling systems that incorporate information about the environment.

From Cues to Signals: Evolution of Interspecific Communication via Aposematism and Mimicry in a Predator-Prey System

PubMed Central

Lehmann, Kenna D. S.; Goldman, Brian W.; Dworkin, Ian; Bryson, David M.; Wagner, Aaron P.

2014-01-01

Current theory suggests that many signaling systems evolved from preexisting cues. In aposematic systems, prey warning signals benefit both predator and prey. When the signal is highly beneficial, a third species often evolves to mimic the toxic species, exploiting the signaling system for its own protection. We investigated the evolutionary dynamics of predator cue utilization and prey signaling in a digital predator-prey system in which prey could evolve to alter their appearance to mimic poison-free or poisonous prey. In predators, we observed rapid evolution of cue recognition (i.e. active behavioral responses) when presented with sufficiently poisonous prey. In addition, active signaling (i.e. mimicry) evolved in prey under all conditions that led to cue utilization. Thus we show that despite imperfect and dishonest signaling, given a high cost of consuming poisonous prey, complex systems of interspecific communication can evolve via predator cue recognition and prey signal manipulation. This provides evidence supporting hypotheses that cues may serve as stepping-stones in the evolution of more advanced communication and signaling systems that incorporate information about the environment. PMID:24614755

Social media is all about video these days: tips communicating science from NASA's Earth Right Now

NASA Astrophysics Data System (ADS)

Bell, S.

2016-12-01

If you're not producing video to communicate your science findings, you're missing the boat navigating the ever-evolving currents of social media. NASA's Earth Right Now communications team made video a priority the past year as we engaged a massive online audience on social media. We will share best practices on social media, lessons learned, what's on the horizon and storytelling techniques to try. PBS documentary-style is passé. Welcome to the world of ten-second Snaps, text-on-picture CNN stories, Facebook Live events and 360° video experiences. Your audience is out there, you just need to catch their attention.

Lethocerus americanus, the "toe biter".

PubMed

Huntley, A

1998-10-01

Lethocerus americanus is a large water bug commonly found in ponds and slowly moving fresh water. Also known as the "toe biter" for its encounters with swimmers, it has the reputation of inflicting painful bites when carelessly handled. It normally feeds on other pond life: insects, tadpoles, salamander, small fish, and snails. These large tan or brown bugs may leave their habitat at night in search of mates or another pond. It is thought that the relative nearness of bright lights for a creature that evolved using celestial navigation, results in disorientation, spiral flight paths, and eventual death from exhaustion. This would account for the occasional find of several dead giant water bugs underneath street lamps.

Control - Demands mushroom as station grows

NASA Technical Reports Server (NTRS)

Szirmay, S. Z.; Blair, J.

1983-01-01

The NASA space station, which is presently in the planning stage, is to be composed of both rigid and nonrigid modules, rotating elements, and flexible appendages subjected to environmental disturbances from the earth's atmospheric gravity gradient, and magnetic field, as well as solar radiation and self-generated disturbances. Control functions, which will originally include attitude control, docking and berthing control, and system monitoring and management, will with evolving mission objectives come to encompass such control functions as articulation control, autonomous navigation, space traffic control, and large space structure control. Attention is given to the advancements in modular, distributed, and adaptive control methods, as well as system identification and hardware fault tolerance techniques, which will be required.

On the evolving portfolio of community-standards and data sharing policies: turning challenges into new opportunities.

PubMed

Sansone, Susanna-Assunta; Rocca-Serra, Philippe

2012-07-12

There are thousands of biology databases with hundreds of terminologies, reporting guidelines, representations models, and exchange formats to help annotate, report, and share bioscience investigations. It is evident, however, that researchers and bioinformaticians struggle to navigate the various standards and to find the appropriate database to collect, manage, and share data. Further, policy makers, funders, and publishers lack sufficient information to formulate their guidelines. In this paper, we highlight a number of key issues that can be used to turn these challenges into new opportunities. It is time for all stakeholders to work together to reconcile cause and effect and make the data-sharing culture functional and efficient.

Spherical Occulter Coronagraph Cubesat

NASA Technical Reports Server (NTRS)

Davila, Joseph M. (Inventor); Rabin, Douglas M. (Inventor); Reginald, Nelson (Inventor); Gong, Qian (Inventor); Shah, Neerav (Inventor); Chamberlin, Phillip C. (Inventor)

2018-01-01

The present invention relates to a space-based instrument which provides continuous coronal electron temperature and velocity images, for a predetermined period of time, thereby improving the understanding of coronal evolution and how the solar wind and Coronal Mass Ejection transients evolve from the low solar atmosphere through the heliosphere for an entire solar rotation. Specifically, the present invention relates to using a 6U spherical occulter coronagraph CubeSat, and a relative navigational system (RNS) that controls the position of the spacecraft relative to the occulting sphere. The present invention innovatively deploys a free-flying spherical occulter, and after deployment, the actively controlled CubeSat will provide an inertial formation flying with the spherical occulter and Sun.

Using the RxNorm web services API for quality assurance purposes.

PubMed

Peters, Lee; Bodenreider, Olivier

2008-11-06

Auditing large, rapidly evolving terminological systems is still a challenge. In the case of RxNorm, a standardized nomenclature for clinical drugs, we argue that quality assurance processes can benefit from the recently released application programming interface (API) provided by RxNav. We demonstrate the usefulness of the API by performing a systematic comparison of alternative paths in the RxNorm graph, over several thousands of drug entities. This study revealed potential errors in RxNorm, currently under review. The results also prompted us to modify the implementation of RxNav to navigate the RxNorm graph more accurately. The RxNav web services API used in this experiment is robust and fast.

Using the RxNorm Web Services API for Quality Assurance Purposes

PubMed Central

Peters, Lee; Bodenreider, Olivier

2008-01-01

Auditing large, rapidly evolving terminological systems is still a challenge. In the case of RxNorm, a standardized nomenclature for clinical drugs, we argue that quality assurance processes can benefit from the recently released application programming interface (API) provided by RxNav. We demonstrate the usefulness of the API by performing a systematic comparison of alternative paths in the RxNorm graph, over several thousands of drug entities. This study revealed potential errors in RxNorm, currently under review. The results also prompted us to modify the implementation of RxNav to navigate the RxNorm graph more accurately. The RxNorm web services API used in this experiment is robust and fast. PMID:18999038

BSSA: Worth thinking about

USGS Publications Warehouse

Michael, Andrew J.

2009-01-01

The Bulletin of the Seismological Society of America (BSSA) is a powerful community project that has helped us share the information necessary to keep our field moving forward since 1911. In some ways, BSSA is much like it has always been, and each issue provides us with a collection of research that has been improved by the peer review process and copyedited, typeset, and printed to make it easily readable. But BSSA has also constantly evolved, and the online edition with full-text searching of all content back to volume 1 and linked references that speed our navigation through the related literature is unlike anything J. C. Branner could have imagined when he edited the first issue.

The quantitative theory of within-host viral evolution

NASA Astrophysics Data System (ADS)

Rouzine, Igor M.; Weinberger, Leor S.

2013-01-01

During the 1990s, a group of virologists and physicists began development of a quantitative theory to explain the rapid evolution of human immunodeficiency virus type 1 (HIV-1). This theory also proved to be instrumental in understanding the rapid emergence of drug resistance in patients. Over the past two decades, this theory expanded to account for a broad array of factors important to viral evolution and propelled development of a generalized theory applicable to a broad range of asexual and partly sexual populations with many evolving sites. Here, we discuss the conceptual and theoretical tools developed to calculate the speed and other parameters of evolution, with a particular focus on the concept of ‘clonal interference’ and its applications to untreated patients.

Advocates and critics for tactical behaviors in UGV navigation

NASA Astrophysics Data System (ADS)

Hussain, Talib S.; Vidaver, Gordon; Berliner, Jeffrey

2005-05-01

Critical to the development of unmanned ground vehicle platforms is the incorporation of adaptive tactical behaviors for the planning of high-level navigation and tactical actions. BBN Technologies recently completed a simulation-based project for the Army Research Lab (ARL) in which we applied an evolutionary computation approach to navigating through a terrain to capture flag objectives while faced with one or more mobile enemies. Our Advocates and Critics for Tactical Behaviors (ACTB) system evolves plans for the vehicle that control its movement goals (in the form of waypoints), and its future actions (e.g., pointing cameras). We apply domain-specific, state-dependent genetic operators called advocates that promote specific tactical behaviors (e.g., adapt a plan to stay closer to walls). We define the fitness function as a weighted sum of a number of independent, domain-specific, state-dependent evaluation components called critics. Critics reward plans based upon specific tactical criteria, such as minimizing risk of exposure or time to the flags. Additionally, the ACTB system provides the capability for a human commander to specify the "rules of engagement" under which the vehicle will operate. The rules of engagement determine the planning emphasis required under different tactical situations (e.g., discovery of an enemy), and provide a mechanism for automatically adapting the relative selection probabilities of the advocates, the weights of the critics, and the depth of planning in response to tactical events. The ACTB system demonstrated highly effective performance in a head-to-head testing event, held by ARL, against two competing tactical behavior systems.

Integration of a 3D perspective view in the navigation display: featuring pilot's mental model

NASA Astrophysics Data System (ADS)

Ebrecht, L.; Schmerwitz, S.

2015-05-01

Synthetic vision systems (SVS) appear as spreading technology in the avionic domain. Several studies prove enhanced situational awareness when using synthetic vision. Since the introduction of synthetic vision a steady change and evolution started concerning the primary flight display (PFD) and the navigation display (ND). The main improvements of the ND comprise the representation of colored ground proximity warning systems (EGPWS), weather radar, and TCAS information. Synthetic vision seems to offer high potential to further enhance cockpit display systems. Especially, concerning the current trend having a 3D perspective view in a SVS-PFD while leaving the navigational content as well as methods of interaction unchanged the question arouses if and how the gap between both displays might evolve to a serious problem. This issue becomes important in relation to the transition and combination of strategic and tactical flight guidance. Hence, pros and cons of 2D and 3D views generally as well as the gap between the egocentric perspective 3D view of the PFD and the exocentric 2D top and side view of the ND will be discussed. Further a concept for the integration of a 3D perspective view, i.e., bird's eye view, in synthetic vision ND will be presented. The combination of 2D and 3D views in the ND enables a better correlation of the ND and the PFD. Additionally, this supports the building of pilot's mental model. The authors believe it will improve the situational and spatial awareness. It might prove to further raise the safety margin when operating in mountainous areas.

Ultrasonic predator-prey interactions in water-convergent evolution with insects and bats in air?

PubMed

Wilson, Maria; Wahlberg, Magnus; Surlykke, Annemarie; Madsen, Peter Teglberg

2013-01-01

Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound and exhibit evasive maneuvers when exposed to bat calls. Among aquatic prey on the other hand, the ability to detect and avoid ultrasound emitting predators seems to be limited to only one subfamily of Clupeidae: the Alosinae (shad and menhaden). These differences are likely rooted in the different physical properties of air and water where cuticular mechanoreceptors have been adapted to serve as ultrasound sensitive ears, whereas ultrasound detection in water have called for sensory cells mechanically connected to highly specialized gas volumes that can oscillate at high frequencies. In addition, there are most likely differences in the risk of predation between insects and fish from echolocating predators. The selection pressure among insects for evolving ultrasound sensitive ears is high, because essentially all nocturnal predation on flying insects stems from echolocating bats. In the interaction between toothed whales and their prey the selection pressure seems weaker, because toothed whales are by no means the only marine predators placing a selection pressure on their prey to evolve specific means to detect and avoid them. Toothed whales can generate extremely intense sound pressure levels, and it has been suggested that they may use these to debilitate prey. Recent experiments, however, show that neither fish with swim bladders, nor squid are debilitated by such signals. This strongly suggests that the production of high amplitude ultrasonic clicks serve the function of improving the detection range of the toothed whale biosonar system rather than debilitation of prey.

"¿Qué Estoy Haciendo Aquí? (What Am I Doing Here?)": Chicanos/Latinos(as) Navigating Challenges and Inequalities During Their First Year of Graduate School

ERIC Educational Resources Information Center

Ramirez, Elvia

2014-01-01

Based on in-depth qualitative interviews, this study analyzed the challenges and structural inequities that Chicanos/Latinos(as) encountered and resisted during their first year of graduate school. Grounded in intersectionality theory, this study analyzed how race, class, and gender inequalities that are embedded in the graduate schooling process…

Perception for Outdoor Navigation

DTIC Science & Technology

1991-12-01

are theories of human cognitive activity during driving. Van der Molen and Botticher recently reviewed several of these models [40]. The models...represent driving knowledge, how to perceive traffic situations, or how to process information to obtain actions. Van der Molen and Botticher attempted to...Conference on Robotics and Automation. IEEE, 1987. [40] van der Molen , H.H., and Botticher, A.M.T. Risk Models for Traffic Participants: A Concerted

Making Space for Diverse Masculinities: Difference, Intersectionality, and Engagement in an Urban High School. Adolescent Cultures, School and Society, Volume 50

ERIC Educational Resources Information Center

McCready, Lance T.

2010-01-01

What's it like for Black male students who are openly gay or "gender non-conforming" to navigate the social geography of urban schools? In the tradition of critical ethnographies of schooling, Lance T. McCready mobilizes feminist theories of intersectionality to explore the voices of Black gay male students and their teachers in a…

Balancing Survival and Resistance: Experiences of Faculty of Color in Predominantly Euro American Schools of Nursing

ERIC Educational Resources Information Center

Lutz, Kristin F.; Hassouneh, Dena; Akeroyd, Jen; Beckett, Ann K.

2013-01-01

This report of findings from a grounded theory study conducted with 23 faculty of color (FOC) in predominately Euro American schools of nursing presents the central process used by FOC as they navigate academic careers as persons of color. As FOC struggled to progress in their careers and influence their academic environments they engaged in a…

Robotic Navigation Emulating Human Performance

DTIC Science & Technology

2012-03-10

information given”. The special role and significance of shape in visual perception was appreciated and highlighted by the Gestalt Psychologists...denigrate this as well as many other contributions of the Gestalt Psychologists to visual perception . The few who did try to work on it tried to formulate... theories and models of FGO without clarifying the ill-defined concepts used by Gestalt Psychologists before the Cognitive Revolution. This led to a

Electronic simulation of a barometric pressure sensor for the meteorological monitor assembly

NASA Technical Reports Server (NTRS)

Guiar, C. N.; Duff, L. W.

1982-01-01

An analysis of the electronic simulation of barometric pressure used to self-test the counter electronics of the digital barometer is presented. The barometer is part of the Meteorological Monitor Assembly that supports navigation in deep space communication. The theory of operation of the digital barometer, the design details, and the verification procedure used with the barometric pressure simulator are presented.

Navigating between Scylla and Charybdis: The Odyssean Leader in a Complex Environment

DTIC Science & Technology

2008-10-21

of action capable of being shared across the organization). See also David A. Kolb , Experiential Learning : Experience as the Source of Learning ...Army GHQ Maneuvers of 1941. Washington D.C.: United States Army Center of Military History, 1991. Kolb , David A. Experiential Learning : Experience...ABSTRACT See Abstract 15. SUBJECT TERMS Leadership, organizational design, complexity, organizational theory , learning organization 16. SECURITY

Stories of Learning, Identity, Navigations and Boundary Crossings in STEM in Non-Dominant Communities: New Imaginaries for Research and Action

ERIC Educational Resources Information Center

Rahm, Jrène

2016-01-01

Marta Civil's paper "STEM Learning Research through a Funds of Knowledge Lens" (see EJ1091567) can be read as a story about her trajectory as a researcher of everyday and school mathematics over time, grounded in sociocultural historical theory. Building on her work, I explore three issues. First, I address the grounding of STEM research…

Low-frequency, self-sustained oscillations in inductively coupled plasmas used for optical pumping

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

Coffer, J.; Encalada, N.; Huang, M.

We have investigated very low frequency, on the order of one hertz, self-pulsing in alkali-metal inductively-coupled plasmas (i.e., rf-discharge lamps). This self-pulsing has the potential to significantly vary signal-to-noise ratios and (via the ac-Stark shift) resonant frequencies in optically pumped atomic clocks and magnetometers (e.g., the atomic clocks now flying on GPS and Galileo global navigation system satellites). The phenomenon arises from a nonlinear interaction between the atomic physics of radiation trapping and the plasma's electrical nature. To explain the effect, we have developed an evaporation/condensation theory (EC theory) of the self-pulsing phenomenon.

Designing a Stability Operations Framework to Achieve National Interests

DTIC Science & Technology

2011-03-01

National Security Strategy (Washington, DC: The White House, May 2010), 17. 3 Ibid., 38. 31 4 Abraham H. Maslow , ―A Theory of Human Motivation...population. Abraham Harold Maslow’s theory of human motivation will be used to demonstrate the pre-eminent and enduring nature of prosperity interests...to pursue peak experiences and self actualization needs is where the majority have evolved. As Maslow explains, this fact does not imply that love

Density functional theory across chemistry, physics and biology.

PubMed

van Mourik, Tanja; Bühl, Michael; Gaigeot, Marie-Pierre

2014-03-13

The past decades have seen density functional theory (DFT) evolve from a rising star in computational quantum chemistry to one of its major players. This Theme Issue, which comes half a century after the publication of the Hohenberg-Kohn theorems that laid the foundations of modern DFT, reviews progress and challenges in present-day DFT research. Rather than trying to be comprehensive, this Theme Issue attempts to give a flavour of selected aspects of DFT.

Career preference theory: A grounded theory describing the effects of undergraduate career preferences on student persistence in engineering

NASA Astrophysics Data System (ADS)

Dettinger, Karen Marie

This study used grounded theory in a case study at a large public research university to develop a theory about how the culture in engineering education affects students with varying interests and backgrounds. According to Career Preference Theory, the engineering education system has evolved to meet the needs of one type of student, the Physical Scientist. While this educational process serves to develop the next generation of engineering faculty members, the majority of engineering undergraduates go on to work as practicing engineers, and are far removed from working as physical scientists. According to Career Preference Theory, students with a history of success in mathematics and sciences, and a focus on career, enter engineering. These students, who actually have a wide range of interests and values, each begin seeking an identity as a practicing engineer. Career Preference Theory is developed around a concept, Career Identity Type, that describes five different types of engineering students: Pragmatic, Physical Scientist, "Social" Scientist, Designer, and Educator. According to the theory, each student must develop an identity within the engineering education system if they are to persist in engineering. However, the current undergraduate engineering education system has evolved in such a way that it meets only the needs of the Physical Scientist. Pragmatic students are also likely to succeed because they tend to be extremely goal-focused and maintain a focus on the rewards they will receive once they graduate with an engineering degree. However, "Social" Scientists, who value interpersonal relationships and giving back to society; Designers, who value integrating ideas across disciplines to create aesthetically pleasing and useful products; and Educators, who have a strong desire to give back to society by working with young people, must make some connection between these values and a future engineering career if they are to persist in engineering. According to Career Preference Theory, "Social" Scientists, Designers, and Educators are likely to leave engineering, while Pragmatics and Physical Scientists are likely to persist.

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

Kim, K. S.; Nakae, L. F.; Prasad, M. K.

Here, we solve a simple theoretical model of time evolving fission chains due to Feynman that generalizes and asymptotically approaches the point model theory. The point model theory has been used to analyze thermal neutron counting data. This extension of the theory underlies fast counting data for both neutrons and gamma rays from metal systems. Fast neutron and gamma-ray counting is now possible using liquid scintillator arrays with nanosecond time resolution. For individual fission chains, the differential equations describing three correlated probability distributions are solved: the time-dependent internal neutron population, accumulation of fissions in time, and accumulation of leaked neutronsmore » in time. Explicit analytic formulas are given for correlated moments of the time evolving chain populations. The equations for random time gate fast neutron and gamma-ray counting distributions, due to randomly initiated chains, are presented. Correlated moment equations are given for both random time gate and triggered time gate counting. There are explicit formulas for all correlated moments are given up to triple order, for all combinations of correlated fast neutrons and gamma rays. The nonlinear differential equations for probabilities for time dependent fission chain populations have a remarkably simple Monte Carlo realization. A Monte Carlo code was developed for this theory and is shown to statistically realize the solutions to the fission chain theory probability distributions. Combined with random initiation of chains and detection of external quanta, the Monte Carlo code generates time tagged data for neutron and gamma-ray counting and from these data the counting distributions.« less

The Geopolitical Destiny of East Asia

DTIC Science & Technology

2011-12-16

equilibrium.5 In brief, for the United States, Eurasian geostrategy involves the purposeful management of geostrategically dynamic states and the......readjust its policy to manage its expectations. Evolving away from his originally aggressive stance of roll back, containment, domino theory advocate

SiO maser polarization in evolved stars: magnetic field

NASA Astrophysics Data System (ADS)

Herpin, F.; Baudry, A.; Thum, C.; Morris, D.; Wiesemeyer, H.

The maser theory still needs to be improved, in particular in terms of polarization. The study of the maser geometry inside the circumstellar envelopes can also be achieved through polarization studies (e.g., VLBI observations). But the most exciting point is the determination of the magnetic field that can be made from polarization measurements: this is definitively a new field of investigation for these evolved objects. The magnetic field probably plays an important role in the AGB star's life and can be a major factor (magnetic rotator theory) on the origin of the high mass loss rates observed in evolved objects. Measurement of the magnetic field is thus essential to study the mass loss mechanisms and also the Alfven waves. During its transition most quasi spherical AGB stars (i.e. envelopes) become complicated aspherical objects. This shaping is well explained by the Interacting Stellar Winds theory (Kwok works), but the ISW model fails to reproduce very complicated structures with jets and ansae. A new model (Magnetized Wind Blown Bubble theory) was thus developed by Blackman et al. (2001) and A. Franck: a weak toroidal magnetic field, embedded in the stellar wind, acts as a collimating agent (cf. Garcia-Segura 1997) and can produce such structures. Three molecules can show polarized maser emission in the circumstellar envelopes: - OH traces the envelope far from the central star (1000-10000 AU) - H2O at intermediate distances (a few 100 AU) - SiO in the inner circumstellar layers (5-10 AU) Measurement of the polarization rate of the maser radiation emitted by these molecules can give us the averaged value B// of the magnetic field along the line of sight (for a single dish observation). We present here the first complete study of the SiO maser polarization in a large sample of evolved stars (more than 100). The 4 Stokes parameters I, U, Q, V were simultaneously measured with the polarimeter on the IRAM-30m telescope. From the Stokes parameters values we derive the linear (pL) and circular (pC) polarization rates and polarization angle. The circular polarization rate gives us directly the magnetic field B//: B// varies from 1 to 32 Gauss depending on the source, with an average value of 9 Gauss.

Quantitative steps in the evolution of metabolic organisation as specified by the Dynamic Energy Budget theory.

PubMed

Kooijman, S A L M; Troost, T A

2007-02-01

The Dynamic Energy Budget (DEB) theory quantifies the metabolic organisation of organisms on the basis of mechanistically inspired assumptions. We here sketch a scenario for how its various modules, such as maintenance, storage dynamics, development, differentiation and life stages could have evolved since the beginning of life. We argue that the combination of homeostasis and maintenance induced the development of reserves and that subsequent increases in the maintenance costs came with increases of the reserve capacity. Life evolved from a multiple reserves - single structure system (prokaryotes, many protoctists) to systems with multiple reserves and two structures (plants) or single reserve and single structure (animals). This had profound consequences for the possible effects of temperature on rates. We present an alternative explanation for what became known as the down-regulation of maintenance at high growth rates in microorganisms; the density of the limiting reserve increases with the growth rate, and reserves do not require maintenance while structure-specific maintenance costs are independent of the growth rate. This is also the mechanism behind the variation of the respiration rate with body size among species. The DEB theory specifies reserve dynamics on the basis of the requirements of weak homeostasis and partitionability. We here present a new and simple mechanism for this dynamics which accounts for the rejection of mobilised reserve by busy maintenance/growth machinery. This module, like quite a few other modules of DEB theory, uses the theory of Synthesising Units; we review recent progress in this field. The plasticity of membranes that evolved in early eukaryotes is a major step forward in metabolic evolution; we discuss quantitative aspects of the efficiency of phagocytosis relative to the excretion of digestive enzymes to illustrate its importance. Some processes of adaptation and gene expression can be understood in terms of allocation linked to the relative workload of metabolic modules in (unicellular) prokaryotes and organs in (multicellular) eukaryotes. We argue that the evolution of demand systems can only be understood in the light of that of supply systems. We illustrate some important points with data from the literature.

A case study of systemic curricular reform: A forty-year history

NASA Astrophysics Data System (ADS)

Laubach, Timothy Alan

What follows is a description of the development of a particular inquiry-based elementary school science curriculum program and how its theoretical underpinnings positively influenced a school district's (K-12) science program and also impacted district- and state-wide curriculum reform initiatives. The district's science program has evolved since the inception of the inquiry-based elementary school science curriculum reform forty years ago. Therefore, a historical case study, which incorporated grounded theory methodology, was used to convey the forty-year development of a science curriculum reform effort and its systemic influences. Data for this study were collected primarily through artifacts, such as technical and non-technical documents, and supported and augmented with interviews. Fifteen people comprised the interview consortium with professional responsibilities including (a) administrative roles, such as superintendents, assistant superintendents, principals, and curriculum consultants/coordinators; (b) classroom roles, such as elementary and secondary school teachers who taught science; (c) partnership roles, such as university faculty who collaborated with those in administrative and classroom positions within the district; and (d) the co-director of SCIS who worked with the SCIS trial center director. Data were analyzed and coded using the constant comparative method. The analysis of data uncovered five categories or levels in which the curriculum reform evolved throughout its duration. These themes are Initiation, Education, Implementation, Confirmation, and Continuation. These five categories lead to several working hypotheses that supported the sustaining and continuing of a K-12 science curriculum reform effort. These components are a committed visionary; a theory base of education; forums promoting the education of the theory base components; shared-decision making; a university-school partnership; a core group of committed educators and teachers; evidences of success; national and state reform initiatives; a core group of administrators; longevity of the science program; district support (philosophical, financial, and emotional); and community support all contributed to the initiation, education, implementation, confirmation, and the continuation of the systemic curricular reform. The underlying component, or grounded theory generated by the study, that ties these experiences together is the "theory base" that concurrently evolved in the local school district and in a nearby university.

Developments in cognitive neuroscience: I. Conflict, compromise, and connectionism.

PubMed

Westen, Drew; Gabbard, Glen O

2002-01-01

The strength of psychoanalysis has always been its understanding of affect and motivation. Contemporary developments in cognitive neuroscience offer possibilities of integrating sophisticated, experimentally informed models of thought and memory with an understanding of dynamically and clinically meaningful processes. Aspects of contemporary theory and research in cognitive neuroscience are integrated with psychoanalytic theory and technique, particularly theories of conflict and compromise. After a description of evolving models of the mind in cognitive neuroscience, several issues relevant to psychoanalytic theory and practice are addressed. These include the nature of representations, the interaction of cognition and affect, and the mechanisms by which the mind unconsciously forges compromise solutions that best fit multiple cognitive and affective-motivational constraints.

Adopting a constructivist approach to grounded theory: implications for research design.

PubMed

Mills, Jane; Bonner, Ann; Francis, Karen

2006-02-01

Grounded theory is a popular research methodology that is evolving to account for a range of ontological and epistemological underpinnings. Constructivist grounded theory has its foundations in relativism and an appreciation of the multiple truths and realities of subjectivism. Undertaking a constructivist enquiry requires the adoption of a position of mutuality between researcher and participant in the research process, which necessitates a rethinking of the grounded theorist's traditional role of objective observer. Key issues for constructivist grounded theorists to consider in designing their research studies are discussed in relation to developing a partnership with participants that enables a mutual construction of meaning during interviews and a meaningful reconstruction of their stories into a grounded theory model.

One hundred years of quantum physics.

PubMed

Kleppner, D; Jackiw, R

2000-08-11

This year marks the 100th anniversary of Max Planck's creation of the quantum concept, an idea so revolutionary that it took nearly 30 years for scientists to develop it into the theory that has transformed the way scientists view reality. In this month's essay, Daniel Kleppner and Roman Jackiw recount how quantum theory, which they rate as "the most precisely tested and most successful theory in the history of science," came to be, how it changed the world, and how it might continue to evolve to make the dream of ultimate understanding of the universe come true.

Theory of void formation in dusty plasmas

NASA Astrophysics Data System (ADS)

Hu, Zuquan; Chen, Yinhua; Zheng, Xiang; Huang, Feng; Shi, Gei-fen; Yu, M. Y.

2009-06-01

A fluid theory of void formation in dusty plasmas taking into account ionization is proposed. It is shown that if the ionization rate is larger than a threshold, an initial steady-state dust-density distribution can evolve into a stable distribution containing a void. As the ionization rate is further increased, the time required for void formation decreases. The void size first increases, but then decreases. However, for still larger ionization rates, the dusty region of the plasma becomes ringlike, including the convection term in dust momentum equation. The results are in agreement with existing experiments and theories.

RELAP-7 Theory Manual

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

Berry, Ray Alden; Zou, Ling; Zhao, Haihua

This document summarizes the physical models and mathematical formulations used in the RELAP-7 code. In summary, the MOOSE based RELAP-7 code development is an ongoing effort. The MOOSE framework enables rapid development of the RELAP-7 code. The developmental efforts and results demonstrate that the RELAP-7 project is on a path to success. This theory manual documents the main features implemented into the RELAP-7 code. Because the code is an ongoing development effort, this RELAP-7 Theory Manual will evolve with periodic updates to keep it current with the state of the development, implementation, and model additions/revisions.

Collapse of cooperation in evolving games.

PubMed

Stewart, Alexander J; Plotkin, Joshua B

2014-12-09

Game theory provides a quantitative framework for analyzing the behavior of rational agents. The Iterated Prisoner's Dilemma in particular has become a standard model for studying cooperation and cheating, with cooperation often emerging as a robust outcome in evolving populations. Here we extend evolutionary game theory by allowing players' payoffs as well as their strategies to evolve in response to selection on heritable mutations. In nature, many organisms engage in mutually beneficial interactions and individuals may seek to change the ratio of risk to reward for cooperation by altering the resources they commit to cooperative interactions. To study this, we construct a general framework for the coevolution of strategies and payoffs in arbitrary iterated games. We show that, when there is a tradeoff between the benefits and costs of cooperation, coevolution often leads to a dramatic loss of cooperation in the Iterated Prisoner's Dilemma. The collapse of cooperation is so extreme that the average payoff in a population can decline even as the potential reward for mutual cooperation increases. Depending upon the form of tradeoffs, evolution may even move away from the Iterated Prisoner's Dilemma game altogether. Our work offers a new perspective on the Prisoner's Dilemma and its predictions for cooperation in natural populations; and it provides a general framework to understand the coevolution of strategies and payoffs in iterated interactions.

A theory for the evolution of other-regard integrating proximate and ultimate perspectives.

PubMed

Akçay, Erol; Van Cleve, Jeremy; Feldman, Marcus W; Roughgarden, Joan

2009-11-10

Although much previous work describes evolutionary mechanisms that promote or stabilize different social behaviors, we still have little understanding of the factors that drive animal behavior proximately. Here we present a modeling approach to answer this question. Our model rests on motivations to achieve objectives as the proximate determinants of behavior. We develop a two-tiered framework by first modeling the dynamics of a social interaction at the behavioral time scale and then find the evolutionarily stable objectives that result from the outcomes these dynamics produce. We use this framework to ask whether "other-regarding" motivations, which result from a kind of nonselfish objective, can evolve when individuals are engaged in a social interaction that entails a conflict between their material payoffs. We find that, at the evolutionarily stable state, individuals can be other-regarding in that they are motivated to increase their partners' payoff as well as their own. In contrast to previous theories, we find that such motivations can evolve because of their direct effect on fitness and do not require kin selection or a special group structure. We also derive general conditions for the evolutionary stability of other-regarding motivations. Our conditions indicate that other-regarding motivations are more likely to evolve when social interactions and behavioral objectives are both synergistic.

A Novel Adaptive H∞ Filtering Method with Delay Compensation for the Transfer Alignment of Strapdown Inertial Navigation Systems

PubMed Central

Lyu, Weiwei

2017-01-01

Transfer alignment is always a key technology in a strapdown inertial navigation system (SINS) because of its rapidity and accuracy. In this paper a transfer alignment model is established, which contains the SINS error model and the measurement model. The time delay in the process of transfer alignment is analyzed, and an H∞ filtering method with delay compensation is presented. Then the H∞ filtering theory and the robust mechanism of H∞ filter are deduced and analyzed in detail. In order to improve the transfer alignment accuracy in SINS with time delay, an adaptive H∞ filtering method with delay compensation is proposed. Since the robustness factor plays an important role in the filtering process and has effect on the filtering accuracy, the adaptive H∞ filter with delay compensation can adjust the value of robustness factor adaptively according to the dynamic external environment. The vehicle transfer alignment experiment indicates that by using the adaptive H∞ filtering method with delay compensation, the transfer alignment accuracy and the pure inertial navigation accuracy can be dramatically improved, which demonstrates the superiority of the proposed filtering method. PMID:29182592

An assisted navigation training framework based on judgment theory using sparse and discrete human-machine interfaces.

PubMed

Lopes, Ana C; Nunes, Urbano

2009-01-01

This paper aims to present a new framework to train people with severe motor disabilities steering an assisted mobile robot (AMR), such as a powered wheelchair. Users with high level of motor disabilities are not able to use standard HMIs, which provide a continuous command signal (e. g. standard joystick). For this reason HMIs providing a small set of simple commands, which are sparse and discrete in time must be used (e. g. scanning interface, or brain computer interface), making very difficult to steer the AMR. In this sense, the assisted navigation training framework (ANTF) is designed to train users driving the AMR, in indoor structured environments, using this type of HMIs. Additionally it provides user characterization on steering the robot, which will later be used to adapt the AMR navigation system to human competence steering the AMR. A rule-based lens (RBL) model is used to characterize users on driving the AMR. Individual judgment performance choosing the best manoeuvres is modeled using a genetic-based policy capturing (GBPC) technique characterized to infer non-compensatory judgment strategies from human decision data. Three user models, at three different learning stages, using the RBL paradigm, are presented.

Configuring the Orion Guidance, Navigation, and Control Flight Software for Automated Sequencing

NASA Technical Reports Server (NTRS)

Odegard, Ryan G.; Siliwinski, Tomasz K.; King, Ellis T.; Hart, Jeremy J.

2010-01-01

The Orion Crew Exploration Vehicle is being designed with greater automation capabilities than any other crewed spacecraft in NASA s history. The Guidance, Navigation, and Control (GN&C) flight software architecture is designed to provide a flexible and evolvable framework that accommodates increasing levels of automation over time. Within the GN&C flight software, a data-driven approach is used to configure software. This approach allows data reconfiguration and updates to automated sequences without requiring recompilation of the software. Because of the great dependency of the automation and the flight software on the configuration data, the data management is a vital component of the processes for software certification, mission design, and flight operations. To enable the automated sequencing and data configuration of the GN&C subsystem on Orion, a desktop database configuration tool has been developed. The database tool allows the specification of the GN&C activity sequences, the automated transitions in the software, and the corresponding parameter reconfigurations. These aspects of the GN&C automation on Orion are all coordinated via data management, and the database tool provides the ability to test the automation capabilities during the development of the GN&C software. In addition to providing the infrastructure to manage the GN&C automation, the database tool has been designed with capabilities to import and export artifacts for simulation analysis and documentation purposes. Furthermore, the database configuration tool, currently used to manage simulation data, is envisioned to evolve into a mission planning tool for generating and testing GN&C software sequences and configurations. A key enabler of the GN&C automation design, the database tool allows both the creation and maintenance of the data artifacts, as well as serving the critical role of helping to manage, visualize, and understand the data-driven parameters both during software development and throughout the life of the Orion project.

Mode and tempo in the evolution of socio-political organization: reconciling 'Darwinian' and 'Spencerian' evolutionary approaches in anthropology.

PubMed

Currie, Thomas E; Mace, Ruth

2011-04-12

Traditional investigations of the evolution of human social and political institutions trace their ancestry back to nineteenth century social scientists such as Herbert Spencer, and have concentrated on the increase in socio-political complexity over time. More recent studies of cultural evolution have been explicitly informed by Darwinian evolutionary theory and focus on the transmission of cultural traits between individuals. These two approaches to investigating cultural change are often seen as incompatible. However, we argue that many of the defining features and assumptions of 'Spencerian' cultural evolutionary theory represent testable hypotheses that can and should be tackled within a broader 'Darwinian' framework. In this paper we apply phylogenetic comparative techniques to data from Austronesian-speaking societies of Island South-East Asia and the Pacific to test hypotheses about the mode and tempo of human socio-political evolution. We find support for three ideas often associated with Spencerian cultural evolutionary theory: (i) political organization has evolved through a regular sequence of forms, (ii) increases in hierarchical political complexity have been more common than decreases, and (iii) political organization has co-evolved with the wider presence of hereditary social stratification.

Sex allocation promotes the stable co-occurrence of competitive species

NASA Astrophysics Data System (ADS)

Kobayashi, Kazuya

2017-03-01

Biodiversity has long been a source of wonder and scientific curiosity. Theoretically, the co-occurrence of competitive species requires niche differentiation, and such differences are well known; however, the neutral theory, which assumes the equivalence of all individuals regardless of the species in a biological community, has successfully recreated observed patterns of biodiversity. In this research, the evolution of sex allocation is demonstrated to be the key to resolving why the neutral theory works well, despite the observed species differences. The sex allocation theory predicts that female-biased allocation evolves in species in declining density and that this allocation improves population growth, which should lead to an increase in density. In contrast, when the density increases, a less biased allocation evolves, which reduces the population growth rate and leads to decreased density. Thus, sex allocation provides a buffer against species differences in population growth. A model incorporating this mechanism demonstrates that hundreds of species can co-occur over 10,000 generations, even in homogeneous environments, and reproduces the observed patterns of biodiversity. This study reveals the importance of evolutionary processes within species for the sustainability of biodiversity. Integrating the entire biological process, from genes to community, will open a new era of ecology.

Mode and tempo in the evolution of socio-political organization: reconciling ‘Darwinian’ and ‘Spencerian’ evolutionary approaches in anthropology

PubMed Central

Currie, Thomas E.; Mace, Ruth

2011-01-01

Traditional investigations of the evolution of human social and political institutions trace their ancestry back to nineteenth century social scientists such as Herbert Spencer, and have concentrated on the increase in socio-political complexity over time. More recent studies of cultural evolution have been explicitly informed by Darwinian evolutionary theory and focus on the transmission of cultural traits between individuals. These two approaches to investigating cultural change are often seen as incompatible. However, we argue that many of the defining features and assumptions of ‘Spencerian’ cultural evolutionary theory represent testable hypotheses that can and should be tackled within a broader ‘Darwinian’ framework. In this paper we apply phylogenetic comparative techniques to data from Austronesian-speaking societies of Island South-East Asia and the Pacific to test hypotheses about the mode and tempo of human socio-political evolution. We find support for three ideas often associated with Spencerian cultural evolutionary theory: (i) political organization has evolved through a regular sequence of forms, (ii) increases in hierarchical political complexity have been more common than decreases, and (iii) political organization has co-evolved with the wider presence of hereditary social stratification. PMID:21357233

Lack of evolvability in self-sustaining autocatalytic networks constraints metabolism-first scenarios for the origin of life.

PubMed

Vasas, Vera; Szathmáry, Eörs; Santos, Mauro

2010-01-26

A basic property of life is its capacity to experience Darwinian evolution. The replicator concept is at the core of genetics-first theories of the origin of life, which suggest that self-replicating oligonucleotides or their similar ancestors may have been the first "living" systems and may have led to the evolution of an RNA world. But problems with the nonenzymatic synthesis of biopolymers and the origin of template replication have spurred the alternative metabolism-first scenario, where self-reproducing and evolving proto-metabolic networks are assumed to have predated self-replicating genes. Recent theoretical work shows that "compositional genomes" (i.e., the counts of different molecular species in an assembly) are able to propagate compositional information and can provide a setup on which natural selection acts. Accordingly, if we stick to the notion of replicator as an entity that passes on its structure largely intact in successive replications, those macromolecular aggregates could be dubbed "ensemble replicators" (composomes) and quite different from the more familiar genes and memes. In sharp contrast with template-dependent replication dynamics, we demonstrate here that replication of compositional information is so inaccurate that fitter compositional genomes cannot be maintained by selection and, therefore, the system lacks evolvability (i.e., it cannot substantially depart from the asymptotic steady-state solution already built-in in the dynamical equations). We conclude that this fundamental limitation of ensemble replicators cautions against metabolism-first theories of the origin of life, although ancient metabolic systems could have provided a stable habitat within which polymer replicators later evolved.

Multiple Aptitude Battery-II Normative Intelligence Test Data That Distinguish U.S. Air Force AC-130 Gunship Sensor Operators

DTIC Science & Technology

2010-06-01

common part of an aeromedical evaluation when there is concern regarding an 50’ s general cognitive ability or specific aptitudes related to medica l...specificity and developmental complexity (Guilford, 1988; Horn, 1985; Vernon, 1961). Theories have also evolved from strictly biological approaches (Ha...tapped directly by existing measures of intellectual ability. Wechsler’s theory of intelligence is central to the development of the mostly widely used

A new view of Baryon symmetric cosmology based on grand unified theories

NASA Technical Reports Server (NTRS)

Stecker, F. W.

1981-01-01

Within the framework of grand unified theories, it is shown how spontaneous CP violation leads to a domain structure in the universe with the domains evolving into separate regions of matter and antimatter excesses. Subsequent to exponential horizon growth, this can result in a universe of matter galaxies and antimatter galaxies. Various astrophysical data appear to favor this form of big bang cosmology. Future direct tests for cosmologically significant antimatter are discussed.

Navigating Survival: Quality of Life Following Bone Marrow Transplantation.

DTIC Science & Technology

1991-01-01

This study explored the quality of life of adult Bone Marrow Transplantation (BMT) survivors and processes involved in maintaining or enhancing life...quality were identified. Ground theory methodology was used to explore quality of life from the survivor’s perspective. Five adults, 87 to 578 days...processes employed by BMT survivors to manage quality of life disruptions. BMT survivors identified disruptions in quality of life during the rapid

Joint University Program for Air Transportation Research, 1989-1990

NASA Technical Reports Server (NTRS)

Morrell, Frederick R. (Compiler)

1990-01-01

Research conducted during the academic year 1989-90 under the NASA/FAA sponsored Joint University Program for Air Transportation research is discussed. Completed works, status reports and annotated bibliographies are presented for research topics, which include navigation, guidance and control theory and practice, aircraft performance, human factors, and expert systems concepts applied to airport operations. An overview of the year's activities for each university is also presented.

Proceedings of the NASA Aerospace Technology Symposium 2002

NASA Technical Reports Server (NTRS)

Bowen, Brent D. (Editor); Fink, Mary M. (Editor); Schaaf, Michaela M. (Editor)

2002-01-01

Reports are presented from the NASA Aerospace Technology Symposium 2002 on the following: Geo-Referenced Altitude Hold For Latex Ballons; NASA Spaceport Research: Opportunities For space Grant and EPSCoR Involvement; Numerical Simulation Of The Combustion Of Fuel Droplets: Applications, Aircraft/Spacecraft Flight Control, Guidance Navigation; Expertise In System Dynamics and Control, Control Theory and Aerospace Education Ooutreach Opportunities; and Technology For The Improvement Of General Aviation Security: A Needs Assessmemt.

Proceedings of Selected Research and Development Presentations at the National Convention of the Association for Educational Communications and Technology (AECT) Sponsored by the Research and Theory Division (20th, St. Louis, Missouri, February 18-22, 1998).

ERIC Educational Resources Information Center

Maushak, Nancy J., Ed.; Schlosser, Charles, Ed.; Lloyd, Thomas N., Ed.; Simonson, Michael, Ed.

1998-01-01

Subjects addressed by the 55 papers in this proceedings include: teaching literacy; hypermedia navigation and design; creating a community of thinkers; analysis-based message design; learner-instruction interactions; representation of time-based information in visual design; presentation interference; professional development through anecdotes;…