Science.gov

Sample records for a-priori unknown environments

  1. Developing detailed a priori 3D models of large environments to aid in robotic navigation tasks

    NASA Astrophysics Data System (ADS)

    Grinstead, Brad; Koschan, Andreas F.; Abidi, Mongi A.

    2004-09-01

    In order to effectively navigate any environment, a robotic vehicle needs to understand the terrain and obstacles native to that environment. Knowledge of its own location and orientation, and knowledge of the region of operation, can greatly improve the robot"s performance. To this end, we have developed a mobile system for the fast digitization of large-scale environments to develop the a priori information needed for prediction and optimization of the robot"s performance. The system collects ground-level video and laser range information, fusing them together to develop accurate 3D models of the target environment. In addition, the system carries a differential Global Positioning System (GPS) as well as an Inertial Navigation System (INS) for determining the position and orientation of the various scanners as they acquire data. Issues involved in the fusion of these various data modalities include: Integration of the position and orientation (pose) sensors" data at varying sampling rates and availability; Selection of "best" geometry in overlapping data cases; Efficient representation of large 3D datasets for real-time processing techniques. Once the models have been created, this data can be used to provide a priori information about negative obstacles, obstructed fields of view, navigation constraints, and focused feature detection.

  2. A Priori Method of Using Photon Activation Analysis to Determine Unknown Trace Element Concentrations in NIST Standards

    SciTech Connect

    Green, Jaromy; Sun Zaijing; Wells, Doug; Benson, Buck; Maschner, Herb

    2009-03-10

    Photon activation analysis detected elements in two NIST standards that did not have reported concentration values. A method is currently being developed to infer these concentrations by using scaling parameters and the appropriate known quantities within the NIST standard itself. Scaling parameters include: threshold, peak and endpoint energies; photo-nuclear cross sections for specific isotopes; Bremstrahlung spectrum; target thickness; and photon flux. Photo-nuclear cross sections and energies from the unknown elements must also be known. With these quantities, the same integral was performed for both the known and unknown elements resulting in an inference of the concentration of the un-reported element based on the reported value. Since Rb and Mn were elements that were reported in the standards, and because they had well-identified peaks, they were used as the standards of inference to determine concentrations of the unreported elements of As, I, Nb, Y, and Zr. This method was tested by choosing other known elements within the standards and inferring a value based on the stated procedure. The reported value of Mn in the first NIST standard was 403{+-}15 ppm and the reported value of Ca in the second NIST standard was 87000 ppm (no reported uncertainty). The inferred concentrations were 370{+-}23 ppm and 80200{+-}8700 ppm respectively.

  3. Search in unknown random environments

    NASA Astrophysics Data System (ADS)

    Gelenbe, Erol

    2010-12-01

    N searchers are sent out by a source in order to locate a fixed object which is at a finite distance D , but the search space is infinite and D would be in general unknown. Each of the searchers has a finite random lifetime, and may be subject to destruction or failures, and it moves independently of other searchers, and at intermediate locations some partial random information may be available about which way to go. When a searcher is destroyed or disabled, or when it “dies naturally,” after some time the source becomes aware of this and it sends out another searcher, which proceeds similarly to the one that it replaces. The search ends when one of the searchers finds the object being sought. We use N coupled Brownian motions to derive a closed form expression for the average search time as a function of D which will depend on the parameters of the problem: the number of searchers, the average lifetime of searchers, the routing uncertainty, and the failure or destruction rate of searchers. We also examine the cost in terms of the total energy that is expended in the search.

  4. Sinus rhythm heart rate estimation in high noise environments by application of a priori RR interval statistics.

    PubMed

    Hopenfeld, Bruce

    2014-08-01

    Most existing heart beat detection algorithms serially process peaks, which can be either noise or true beats. Serial processing can result in inaccurate detections in the context of high noise. The proposed method relies on the relative regularity of sinus rhythm RR interval changes to select the best sequences of peaks in a 5-10 s long segment of cardiac data. The best sequences with a current data segment are subjected to a trending analysis, to determine whether their associated RR intervals fit within a pattern of prior best segments. The RR regularity scores and the results of the trending analysis are combined into a single sequence score and the final sequence for a segment is chosen from the best sequences based on this overall score. The current heart rate estimate is updated with the final sequence's RR interval by an adaptive filter that weights the overall score. Twenty-four hour RR interval records for 54 normal individuals were parsed into 10-s segments and corrupted with spurious 'noise' peaks, which resulted in a revised RR interval series that included a number of false RR intervals. The algorithm was run on these corrupted RR interval series. The percentages of mean heart rate values within 5 beats min(-1) of the true value were 95%, 88% and 77% for 10, 20 and 30 added noise spikes, respectively. The percentages of mean heart rate values within 10 beats min(-1) of the true value were 98%, 96% and 91% for 10, 20 and 30 added noise spikes, respectively. Accuracy was higher for data segments characterized by relatively low RR interval variability. The proposed algorithm shows promise for estimating average heart rate for sinus rhythm in high noise environments.

  5. Autonomous exploration and mapping of unknown environments

    NASA Astrophysics Data System (ADS)

    Owens, Jason; Osteen, Phil; Fields, MaryAnne

    2012-06-01

    Autonomous exploration and mapping is a vital capability for future robotic systems expected to function in arbitrary complex environments. In this paper, we describe an end-to-end robotic solution for remotely mapping buildings. For a typical mapping system, an unmanned system is directed to enter an unknown building at a distance, sense the internal structure, and, barring additional tasks, while in situ, create a 2-D map of the building. This map provides a useful and intuitive representation of the environment for the remote operator. We have integrated a robust mapping and exploration system utilizing laser range scanners and RGB-D cameras, and we demonstrate an exploration and metacognition algorithm on a robotic platform. The algorithm allows the robot to safely navigate the building, explore the interior, report significant features to the operator, and generate a consistent map - all while maintaining localization.

  6. Natural Language Direction Following for Robots in Unstructured Unknown Environments

    DTIC Science & Technology

    2015-01-15

    environment it has observed so far. In other words , absent a full map the robot must incrementally build up its map (using sensor measurements), and rely... environment . In other words , a robot is put in an environment it has never seen or knows anything about, and is then given a natural language instruction...approaches, we will learn the meaning of words using a feature representation, but we will do so in an unknown environment with many more possible

  7. Towards high-speed autonomous navigation of unknown environments

    NASA Astrophysics Data System (ADS)

    Richter, Charles; Roy, Nicholas

    2015-05-01

    In this paper, we summarize recent research enabling high-speed navigation in unknown environments for dynamic robots that perceive the world through onboard sensors. Many existing solutions to this problem guarantee safety by making the conservative assumption that any unknown portion of the map may contain an obstacle, and therefore constrain planned motions to lie entirely within known free space. In this work, we observe that safety constraints may significantly limit performance and that faster navigation is possible if the planner reasons about collision with unobserved obstacles probabilistically. Our overall approach is to use machine learning to approximate the expected costs of collision using the current state of the map and the planned trajectory. Our contribution is to demonstrate fast but safe planning using a learned function to predict future collision probabilities.

  8. Autonomous Underwater Navigation and Optical Mapping in Unknown Natural Environments

    PubMed Central

    Hernández, Juan David; Istenič, Klemen; Gracias, Nuno; Palomeras, Narcís; Campos, Ricard; Vidal, Eduard; García, Rafael; Carreras, Marc

    2016-01-01

    We present an approach for navigating in unknown environments while, simultaneously, gathering information for inspecting underwater structures using an autonomous underwater vehicle (AUV). To accomplish this, we first use our pipeline for mapping and planning collision-free paths online, which endows an AUV with the capability to autonomously acquire optical data in close proximity. With that information, we then propose a reconstruction pipeline to create a photo-realistic textured 3D model of the inspected area. These 3D models are also of particular interest to other fields of study in marine sciences, since they can serve as base maps for environmental monitoring, thus allowing change detection of biological communities and their environment over time. Finally, we evaluate our approach using the Sparus II, a torpedo-shaped AUV, conducting inspection missions in a challenging, real-world and natural scenario. PMID:27472337

  9. Autonomous Underwater Navigation and Optical Mapping in Unknown Natural Environments.

    PubMed

    Hernández, Juan David; Istenič, Klemen; Gracias, Nuno; Palomeras, Narcís; Campos, Ricard; Vidal, Eduard; García, Rafael; Carreras, Marc

    2016-07-26

    We present an approach for navigating in unknown environments while, simultaneously, gathering information for inspecting underwater structures using an autonomous underwater vehicle (AUV). To accomplish this, we first use our pipeline for mapping and planning collision-free paths online, which endows an AUV with the capability to autonomously acquire optical data in close proximity. With that information, we then propose a reconstruction pipeline to create a photo-realistic textured 3D model of the inspected area. These 3D models are also of particular interest to other fields of study in marine sciences, since they can serve as base maps for environmental monitoring, thus allowing change detection of biological communities and their environment over time. Finally, we evaluate our approach using the Sparus II, a torpedo-shaped AUV, conducting inspection missions in a challenging, real-world and natural scenario.

  10. Exploration for Agents with Different Personalities in Unknown Environments

    NASA Astrophysics Data System (ADS)

    Doumit, Sarjoun; Minai, Ali

    We present in this paper a personality-based architecture (PA) that combines elements from the subsumption architecture and reinforcement learning to find alternate solutions for problems facing artificial agents exploring unknown environments. The underlying PA algorithm is decomposed into layers according to the different (non-contiguous) stages that our agent passes in, which in turn are influenced by the sources of rewards present in the environment. The cumulative rewards collected by an agent, in addition to its internal composition serve as factors in shaping its personality. In missions where multiple agents are deployed, our solution-goal is to allow each of the agents develop its own distinct personality in order for the collective to reach a balanced society, which then can accumulate the largest possible amount of rewards for the agent and society as well. The architecture is tested in a simulated matrix world which embodies different types of positive rewards and negative rewards. Varying experiments are performed to compare the performance of our algorithm with other algorithms under the same environment conditions. The use of our architecture accelerates the overall adaptation of the agents to their environment and goals by allowing the emergence of an optimal society of agents with different personalities. We believe that our approach achieves much efficient results when compared to other more restrictive policy designs.

  11. A Priori Analysis of Natural Language Queries.

    ERIC Educational Resources Information Center

    Spiegler, Israel; Elata, Smadar

    1988-01-01

    Presents a model for the a priori analysis of natural language queries which uses an algorithm to transform the query into a logical pattern that is used to determine the answerability of the query. The results of testing by a prototype system implemented in PROLOG are discussed. (20 references) (CLB)

  12. A priori SNR estimation and noise estimation for speech enhancement

    NASA Astrophysics Data System (ADS)

    Yao, Rui; Zeng, ZeQing; Zhu, Ping

    2016-12-01

    A priori signal-to-noise ratio (SNR) estimation and noise estimation are important for speech enhancement. In this paper, a novel modified decision-directed (DD) a priori SNR estimation approach based on single-frequency entropy, named DDBSE, is proposed. DDBSE replaces the fixed weighting factor in the DD approach with an adaptive one calculated according to change of single-frequency entropy. Simultaneously, a new noise power estimation approach based on unbiased minimum mean square error (MMSE) and voice activity detection (VAD), named UMVAD, is proposed. UMVAD adopts different strategies to estimate noise in order to reduce over-estimation and under-estimation of noise. UMVAD improves the classical statistical model-based VAD by utilizing an adaptive threshold to replace the original fixed one and modifies the unbiased MMSE-based noise estimation approach using an adaptive a priori speech presence probability calculated by entropy instead of the original fixed one. Experimental results show that DDBSE can provide greater noise suppression than DD and UMVAD can improve the accuracy of noise estimation. Compared to existing approaches, speech enhancement based on UMVAD and DDBSE can obtain a better segment SNR score and composite measure c ovl score, especially in adverse environments such as non-stationary noise and low-SNR.

  13. A priori SNR estimation and noise estimation for speech enhancement.

    PubMed

    Yao, Rui; Zeng, ZeQing; Zhu, Ping

    2016-01-01

    A priori signal-to-noise ratio (SNR) estimation and noise estimation are important for speech enhancement. In this paper, a novel modified decision-directed (DD) a priori SNR estimation approach based on single-frequency entropy, named DDBSE, is proposed. DDBSE replaces the fixed weighting factor in the DD approach with an adaptive one calculated according to change of single-frequency entropy. Simultaneously, a new noise power estimation approach based on unbiased minimum mean square error (MMSE) and voice activity detection (VAD), named UMVAD, is proposed. UMVAD adopts different strategies to estimate noise in order to reduce over-estimation and under-estimation of noise. UMVAD improves the classical statistical model-based VAD by utilizing an adaptive threshold to replace the original fixed one and modifies the unbiased MMSE-based noise estimation approach using an adaptive a priori speech presence probability calculated by entropy instead of the original fixed one. Experimental results show that DDBSE can provide greater noise suppression than DD and UMVAD can improve the accuracy of noise estimation. Compared to existing approaches, speech enhancement based on UMVAD and DDBSE can obtain a better segment SNR score and composite measure covl score, especially in adverse environments such as non-stationary noise and low-SNR.

  14. Predictive a priori pressure-dependent kinetics.

    PubMed

    Jasper, Ahren W; Pelzer, Kenley M; Miller, James A; Kamarchik, Eugene; Harding, Lawrence B; Klippenstein, Stephen J

    2014-12-05

    The ability to predict the pressure dependence of chemical reaction rates would be a great boon to kinetic modeling of processes such as combustion and atmospheric chemistry. This pressure dependence is intimately related to the rate of collision-induced transitions in energy E and angular momentum J. We present a scheme for predicting this pressure dependence based on coupling trajectory-based determinations of moments of the E,J-resolved collisional transfer rates with the two-dimensional master equation. This completely a priori procedure provides a means for proceeding beyond the empiricism of prior work. The requisite microcanonical dissociation rates are obtained from ab initio transition state theory. Predictions for the CH4 = CH3 + H and C2H3 = C2H2 + H reaction systems are in excellent agreement with experiment.

  15. Measurement, coordination, and the relativized a priori

    NASA Astrophysics Data System (ADS)

    Padovani, Flavia

    2015-11-01

    The problem of measurement is a central issue in the epistemology and methodology of the physical sciences. In recent literature on scientific representation, large emphasis has been put on the "constitutive role" played by measurement procedures as forms of representation. Despite its importance, this issue hardly finds any mention in writings on constitutive principles, viz. in Michael Friedman's account of relativized a priori principles. This issue, instead, was at the heart of Reichenbach's analysis of coordinating principles that has inspired Friedman's interpretation. This paper suggests that these procedures should have a part in an account of constitutive principles of science, and that they could be interpreted following the intuition originally present (but ultimately not fully developed) in Reichenbach's early work.

  16. Optimal and Efficient Path Planning for Unknown and Dynamic Environments

    DTIC Science & Technology

    1993-08-01

    Figure 1 : Backpointers Based on Initial Propagation from Goal State 10 Figure 2 : Robot Discovers First Unknown Obstacle Cell I 1 Figure 3 : Robot...Moves Up in Search of Path around Obstacle 11 Figure 4 : Robot Moves Down in Search of Path around Obstacle 12 Figure 5 : RAISE States Propagate out of...Dynamic Obstacle 25 Figure 14 : Discovering that the Obstacle has Moved 25 Figure 15 : Path Planning with Potential Fields 26 Figure 16 : Path Planning

  17. Pattern Recognition Algorithm for High-Sensitivity Odorant Detection in Unknown Environments

    NASA Technical Reports Server (NTRS)

    Duong, Tuan A.

    2012-01-01

    In a realistic odorant detection application environment, the collected sensory data is a mix of unknown chemicals with unknown concentrations and noise. The identification of the odorants among these mixtures is a challenge in data recognition. In addition, deriving their individual concentrations in the mix is also a challenge. A deterministic analytical model was developed to accurately identify odorants and calculate their concentrations in a mixture with noisy data.

  18. Integrating a priori information in edge-linking algorithms

    NASA Astrophysics Data System (ADS)

    Farag, Aly A.; Cao, Yu; Yeap, Yuen-Pin

    1992-09-01

    This research presents an approach to integrate a priori information to the path metric of the LINK algorithm. The zero-crossing contours of the $DEL2G are taken as a gross estimate of the boundaries in the image. This estimate of the boundaries is used to define the swath of important information, and to provide a distance measure for edge localization. During the linking process, a priori information plays important roles in (1) dramatically reducing the search space because the actual path lies within +/- 2 (sigma) f from the prototype contours ((sigma) f is the standard deviation of the Gaussian kernel used in the edge enhancement step); (2) breaking the ties when the search metrics give uncertain information; and (3) selecting the set of goal nodes for the search algorithm. We show that the integration of a priori information in the LINK algorithms provides faster and more accurate edge linking.

  19. The Influence of "a priori" Ideas on the Experimental Approach.

    ERIC Educational Resources Information Center

    Cauzinille-Marmeche, Evelyne; And Others

    1985-01-01

    Investigated the role of "a priori" ideas in planning experiments and data processing leading to inferences. Thirty-one students (ages 11-13) observed a "combustion/candle in a closed container" experiment and were asked to interpret sets of measurements. Findings, among others, show that children preferentially experiment on…

  20. "A Priori" Assessment of Language Learning Tasks by Practitioners

    ERIC Educational Resources Information Center

    Westhoff, Gerard J.

    2009-01-01

    Teachers' competence to estimate the effectiveness of learning materials is important and often neglected in programmes for teacher education. In this lecture I will try to explore the possibilities of designing scaffolding instruments for a "priori" assessment of language learning tasks, based on insights from SLA and cognitive psychology, more…

  1. The Influence of "a priori" Ideas on the Experimental Approach.

    ERIC Educational Resources Information Center

    Cauzinille-Marmeche, Evelyne; And Others

    1985-01-01

    Investigated the role of "a priori" ideas in planning experiments and data processing leading to inferences. Thirty-one students (ages 11-13) observed a "combustion/candle in a closed container" experiment and were asked to interpret sets of measurements. Findings, among others, show that children preferentially experiment on…

  2. "A Priori" Assessment of Language Learning Tasks by Practitioners

    ERIC Educational Resources Information Center

    Westhoff, Gerard J.

    2009-01-01

    Teachers' competence to estimate the effectiveness of learning materials is important and often neglected in programmes for teacher education. In this lecture I will try to explore the possibilities of designing scaffolding instruments for a "priori" assessment of language learning tasks, based on insights from SLA and cognitive psychology, more…

  3. Space Invariant Independent Component Analysis and ENose for Detection of Selective Chemicals in an Unknown Environment

    NASA Technical Reports Server (NTRS)

    Duong, Tuan A.; Ryan, Margaret A.; Duong, Vu A.

    2007-01-01

    In this paper, we present a space invariant architecture to enable the Independent Component Analysis (ICA) to solve chemical detection from two unknown mixing chemical sources. The two sets of unknown paired mixture sources are collected via JPL 16-ENose sensor array in the unknown environment with, at most, 12 samples data collected. Our space invariant architecture along with the maximum entropy information technique by Bell and Sejnowski and natural gradient descent by Amari has demonstrated that it is effective to separate the two mixing unknown chemical sources with unknown mixing levels to the array of two original sources under insufficient sampled data. From separated sources, they can be identified by projecting them on the 11 known chemical sources to find the best match for detection. We also present the results of our simulations. These simulations have shown that 100% correct detection could be achieved under the two cases: a) under-completed case where the number of input (mixtures) is larger than number of original chemical sources; and b) regular case where the number of input is as the same as the number of sources while the time invariant architecture approach may face the obstacles: overcomplete case, insufficient data and cumbersome architecture.

  4. Structural a priori information in near-infrared optical tomography

    NASA Astrophysics Data System (ADS)

    Dehghani, Hamid; Carpenter, Colin M.; Yalavarthy, Phaneendra K.; Pogue, Brian W.; Culver, Joseph P.

    2007-02-01

    Recent interest in the use of dual modality imaging in the field of optical Near Infrared (NIR) Tomography has increased, specifically with use of structural information, from for example, MRI. Although MRI images provide high resolution structural information about tissue, they lack the contrast and functional information needed to investigate physiology, whereas NIR data has been established as a high contrast imaging modality, but one which suffers from low resolution. To this effect, the use of dual modality data has been shown to increase the qualitative and quantitative accuracy of clinical information that can be obtained from tissue. Results so far have indicated that providing accurate apriori structural information is available, such dual modality imaging techniques can be used for the detection and characterization of breast cancer in-vivo, as well as the investigation of brain function and physiology in both human and small animal studies. Although there has been much interest and research into the best suitable and robust use of a-priori structural information within the reconstruction of optical properties of tissue, little work has been done into the investigation of how much accuracy is needed from the structural MRI images in order to obtain the most clinically reliable information. In this paper, we will present and demonstrate the two most common application of a-priori information into image reconstruction, namely soft and hard priori. The effect of inaccuracies of the a-priori structural information within the reconstructed NIR images are presented showing that providing that the error of the a-priori information is within 20% in terms of size and location, adequate NIR images can be reconstructed.

  5. Learning to improve medical decision making from imbalanced data without a priori cost.

    PubMed

    Wan, Xiang; Liu, Jiming; Cheung, William K; Tong, Tiejun

    2014-12-05

    In a medical data set, data are commonly composed of a minority (positive or abnormal) group and a majority (negative or normal) group and the cost of misclassifying a minority sample as a majority sample is highly expensive. This is the so-called imbalanced classification problem. The traditional classification functions can be seriously affected by the skewed class distribution in the data. To deal with this problem, people often use a priori cost to adjust the learning process in the pursuit of optimal classification function. However, this priori cost is often unknown and hard to estimate in medical decision making. In this paper, we propose a new learning method, named RankCost, to classify imbalanced medical data without using a priori cost. Instead of focusing on improving the class-prediction accuracy, RankCost is to maximize the difference between the minority class and the majority class by using a scoring function, which translates the imbalanced classification problem into a partial ranking problem. The scoring function is learned via a non-parametric boosting algorithm. We compare RankCost to several representative approaches on four medical data sets varying in size, imbalanced ratio, and dimension. The experimental results demonstrate that unlike the currently available methods that often perform unevenly with different priori costs, RankCost shows comparable performance in a consistent manner. It is a challenging task to learn an effective classification model based on imbalanced data in medical data analysis. The traditional approaches often use a priori cost to adjust the learning of the classification function. This work presents a novel approach, namely RankCost, for learning from medical imbalanced data sets without using a priori cost. The experimental results indicate that RankCost performs very well in imbalanced data classification and can be a useful method in real-world applications of medical decision making.

  6. Automatic Artifact Removal from Electroencephalogram Data Based on A Priori Artifact Information.

    PubMed

    Zhang, Chi; Tong, Li; Zeng, Ying; Jiang, Jingfang; Bu, Haibing; Yan, Bin; Li, Jianxin

    2015-01-01

    Electroencephalogram (EEG) is susceptible to various nonneural physiological artifacts. Automatic artifact removal from EEG data remains a key challenge for extracting relevant information from brain activities. To adapt to variable subjects and EEG acquisition environments, this paper presents an automatic online artifact removal method based on a priori artifact information. The combination of discrete wavelet transform and independent component analysis (ICA), wavelet-ICA, was utilized to separate artifact components. The artifact components were then automatically identified using a priori artifact information, which was acquired in advance. Subsequently, signal reconstruction without artifact components was performed to obtain artifact-free signals. The results showed that, using this automatic online artifact removal method, there were statistical significant improvements of the classification accuracies in both two experiments, namely, motor imagery and emotion recognition.

  7. Solution of underdetermined systems of equations with gridded a priori constraints.

    PubMed

    Stiros, Stathis C; Saltogianni, Vasso

    2014-01-01

    The TOPINV, Topological Inversion algorithm (or TGS, Topological Grid Search) initially developed for the inversion of highly non-linear redundant systems of equations, can solve a wide range of underdetermined systems of non-linear equations. This approach is a generalization of a previous conclusion that this algorithm can be used for the solution of certain integer ambiguity problems in Geodesy. The overall approach is based on additional (a priori) information for the unknown variables. In the past, such information was used either to linearize equations around approximate solutions, or to expand systems of observation equations solved on the basis of generalized inverses. In the proposed algorithm, the a priori additional information is used in a third way, as topological constraints to the unknown n variables, leading to an R(n) grid containing an approximation of the real solution. The TOPINV algorithm does not focus on point-solutions, but exploits the structural and topological constraints in each system of underdetermined equations in order to identify an optimal closed space in the R(n) containing the real solution. The centre of gravity of the grid points defining this space corresponds to global, minimum-norm solutions. The rationale and validity of the overall approach are demonstrated on the basis of examples and case studies, including fault modelling, in comparison with SVD solutions and true (reference) values, in an accuracy-oriented approach.

  8. A priori discretization quality metrics for distributed hydrologic modeling applications

    NASA Astrophysics Data System (ADS)

    Liu, Hongli; Tolson, Bryan; Craig, James; Shafii, Mahyar; Basu, Nandita

    2016-04-01

    In distributed hydrologic modelling, a watershed is treated as a set of small homogeneous units that address the spatial heterogeneity of the watershed being simulated. The ability of models to reproduce observed spatial patterns firstly depends on the spatial discretization, which is the process of defining homogeneous units in the form of grid cells, subwatersheds, or hydrologic response units etc. It is common for hydrologic modelling studies to simply adopt a nominal or default discretization strategy without formally assessing alternative discretization levels. This approach lacks formal justifications and is thus problematic. More formalized discretization strategies are either a priori or a posteriori with respect to building and running a hydrologic simulation model. A posteriori approaches tend to be ad-hoc and compare model calibration and/or validation performance under various watershed discretizations. The construction and calibration of multiple versions of a distributed model can become a seriously limiting computational burden. Current a priori approaches are more formalized and compare overall heterogeneity statistics of dominant variables between candidate discretization schemes and input data or reference zones. While a priori approaches are efficient and do not require running a hydrologic model, they do not fully investigate the internal spatial pattern changes of variables of interest. Furthermore, the existing a priori approaches focus on landscape and soil data and do not assess impacts of discretization on stream channel definition even though its significance has been noted by numerous studies. The primary goals of this study are to (1) introduce new a priori discretization quality metrics considering the spatial pattern changes of model input data; (2) introduce a two-step discretization decision-making approach to compress extreme errors and meet user-specified discretization expectations through non-uniform discretization threshold

  9. Real-time map building and navigation for autonomous robots in unknown environments.

    PubMed

    Oriolo, G; Ulivi, G; Vendittelli, M

    1998-01-01

    An algorithmic solution method is presented for the problem of autonomous robot motion in completely unknown environments. Our approach is based on the alternate execution of two fundamental processes: map building and navigation. In the former, range measures are collected through the robot exteroceptive sensors and processed in order to build a local representation of the surrounding area. This representation is then integrated in the global map so far reconstructed by filtering out insufficient or conflicting information. In the navigation phase, an A*-based planner generates a local path from the current robot position to the goal. Such a path is safe inside the explored area and provides a direction for further exploration. The robot follows the path up to the boundary of the explored area, terminating its motion if unexpected obstacles are encountered. The most peculiar aspects of our method are the use of fuzzy logic for the efficient building and modification of the environment map, and the iterative application of A*, a complete planning algorithm which takes full advantage of local information. Experimental results for a NOMAD 200 mobile robot show the real-time performance of the proposed method, both in static and moderately dynamic environments.

  10. Airborne laser scanner aided inertial for terrain referenced navigation in unknown environments

    NASA Astrophysics Data System (ADS)

    Vadlamani, Ananth Kalyan

    A dead-reckoning terrain referenced navigation (TRN) system that uses airborne laser ranging sensors to aid an aircraft inertial navigation system (INS) is presented. Improved navigation performance is achieved through estimation of vehicle velocity and position using terrain measurements. The system only uses aircraft sensors and simultaneously performs the dual functions of mapping and navigation in unknown environments. The theory, algorithms and results of the system performance are presented using simulations and flight test data. This dissertation focuses primarily on the use of dual airborne laser scanners (ALS) for aiding an INS. Dual ALS measurements are used to generate overlapping terrain models, which are then used to estimate the INS velocity and position errors and constrain its drift. By keeping track of its errors, a navigation-grade INS is aided in a feed-forward manner. This dead-reckoning navigation algorithm is generic enough to be easily extendable to use other optical sensors. Data integrity, sensor alignment and the effects of vegetation noise, attitude and heading accuracy are analyzed. Furthermore, a feedback coupled aiding scheme is presented in which a tactical-grade inertial measurement unit (IMU) is aided with dual ALS measurements by feeding the estimated velocity back into the IMU computations. The proposed system can potentially serve as a backup during temporary Global Positioning System (GPS) signal outages, or it can be used to coast for extended periods of time. Although it has elements of conventional TRN, this system does not require a terrain database since its in-flight mapping capability generates the terrain data for navigation. Hence, the system can be used in both non-GPS as well as unknown terrain environments. The navigation system is dead-reckoning in nature and errors accumulate over time, unless the system can be reset periodically by geo-referenced terrain data or a position estimate from another navigation aid.

  11. Effects of a priori liking on the elicitation of mimicry.

    PubMed

    Stel, Mariëlle; van Baaren, Rick B; Blascovich, Jim; van Dijk, Eric; McCall, Cade; Pollmann, Monique M H; van Leeuwen, Matthijs L; Mastop, Jessanne; Vonk, Roos

    2010-01-01

    Mimicry and prosocial feelings are generally thought to be positively related. However, the conditions under which mimicry and liking are related largely remain unspecified. We advance this specification by examining the relationship between mimicry and liking more thoroughly. In two experiments, we manipulated an individual's a priori liking for another and investigated whether it influenced mimicry of that person. Our experiments demonstrate that in the presence of a reason to like a target, automatic mimicry is increased. However, mimicry did not decrease when disliking a target. These studies provide further evidence of a link between mimicry and liking and extend previous research by showing that a certain level of mimicry even occurs when mimicry behavior is inconsistent with one's goals or motivations.

  12. Onboard star identification without a priori attitude information

    NASA Astrophysics Data System (ADS)

    Ketchum, Eleanor A.; Tolson, Robert H.

    1995-03-01

    Many algorithms used today determine spacecraft attitude by identifying stars in the field of view of a star tracker. However, each of these methods require some a priori knowledge of the spacecraft attitude. Some algorithms have been extended to implement a computation-intense full-sky scan. Others require large data bases. Both storage and speed are concerns for autonomous onboard systems. This paper presents an algorithm that, by discretizing the sky and filtering by visual magnitude of the brightest observed star, provides a star identification process that is computationally efficient, compared to existing techniques. A savings in onboard storage of over 80% compared with a popular existing technique is documented. Results of random tests with simulated star fields are presented without false identification and with dramatic increase in speed over full-sky scan methods.

  13. A priori physicalism, lonely ghosts and Cartesian doubt.

    PubMed

    Goff, Philip

    2012-06-01

    A zombie is a physical duplicates of a human being which lacks consciousness. A ghost is a phenomenal duplicate of a human being whose nature is exhausted by consciousness. Discussion of zombie arguments, that is anti-physicalist arguments which appeal to the conceivability of zombies, is familiar in the philosophy of mind literature, whilst ghostly arguments, that is, anti-physicalist arguments which appeal to the conceivability of ghosts, are somewhat neglected. In this paper I argue that ghostly arguments have a number of dialectical advantages over zombie arguments. I go onto explain how the conceivability of ghosts is inconsistent with two kinds of a priori physicalism: analytic functionalism and the Australian physicalism of Armstrong and Lewis. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. A priori discretization error metrics for distributed hydrologic modeling applications

    NASA Astrophysics Data System (ADS)

    Liu, Hongli; Tolson, Bryan A.; Craig, James R.; Shafii, Mahyar

    2016-12-01

    Watershed spatial discretization is an important step in developing a distributed hydrologic model. A key difficulty in the spatial discretization process is maintaining a balance between the aggregation-induced information loss and the increase in computational burden caused by the inclusion of additional computational units. Objective identification of an appropriate discretization scheme still remains a challenge, in part because of the lack of quantitative measures for assessing discretization quality, particularly prior to simulation. This study proposes a priori discretization error metrics to quantify the information loss of any candidate discretization scheme without having to run and calibrate a hydrologic model. These error metrics are applicable to multi-variable and multi-site discretization evaluation and provide directly interpretable information to the hydrologic modeler about discretization quality. The first metric, a subbasin error metric, quantifies the routing information loss from discretization, and the second, a hydrological response unit (HRU) error metric, improves upon existing a priori metrics by quantifying the information loss due to changes in land cover or soil type property aggregation. The metrics are straightforward to understand and easy to recode. Informed by the error metrics, a two-step discretization decision-making approach is proposed with the advantage of reducing extreme errors and meeting the user-specified discretization error targets. The metrics and decision-making approach are applied to the discretization of the Grand River watershed in Ontario, Canada. Results show that information loss increases as discretization gets coarser. Moreover, results help to explain the modeling difficulties associated with smaller upstream subbasins since the worst discretization errors and highest error variability appear in smaller upstream areas instead of larger downstream drainage areas. Hydrologic modeling experiments under

  15. Evolutionary Fuzzy Control and Navigation for Two Wheeled Robots Cooperatively Carrying an Object in Unknown Environments.

    PubMed

    Juang, Chia-Feng; Lai, Min-Ge; Zeng, Wan-Ting

    2015-09-01

    This paper presents a method that allows two wheeled, mobile robots to navigate unknown environments while cooperatively carrying an object. In the navigation method, a leader robot and a follower robot cooperatively perform either obstacle boundary following (OBF) or target seeking (TS) to reach a destination. The two robots are controlled by fuzzy controllers (FC) whose rules are learned through an adaptive fusion of continuous ant colony optimization and particle swarm optimization (AF-CACPSO), which avoids the time-consuming task of manually designing the controllers. The AF-CACPSO-based evolutionary fuzzy control approach is first applied to the control of a single robot to perform OBF. The learning approach is then applied to achieve cooperative OBF with two robots, where an auxiliary FC designed with the AF-CACPSO is used to control the follower robot. For cooperative TS, a rule for coordination of the two robots is developed. To navigate cooperatively, a cooperative behavior supervisor is introduced to select between cooperative OBF and cooperative TS. The performance of the AF-CACPSO is verified through comparisons with various population-based optimization algorithms for the OBF learning problem. Simulations and experiments verify the effectiveness of the approach for cooperative navigation of two robots.

  16. A hybrid search algorithm for swarm robots searching in an unknown environment.

    PubMed

    Li, Shoutao; Li, Lina; Lee, Gordon; Zhang, Hao

    2014-01-01

    This paper proposes a novel method to improve the efficiency of a swarm of robots searching in an unknown environment. The approach focuses on the process of feeding and individual coordination characteristics inspired by the foraging behavior in nature. A predatory strategy was used for searching; hence, this hybrid approach integrated a random search technique with a dynamic particle swarm optimization (DPSO) search algorithm. If a search robot could not find any target information, it used a random search algorithm for a global search. If the robot found any target information in a region, the DPSO search algorithm was used for a local search. This particle swarm optimization search algorithm is dynamic as all the parameters in the algorithm are refreshed synchronously through a communication mechanism until the robots find the target position, after which, the robots fall back to a random searching mode. Thus, in this searching strategy, the robots alternated between two searching algorithms until the whole area was covered. During the searching process, the robots used a local communication mechanism to share map information and DPSO parameters to reduce the communication burden and overcome hardware limitations. If the search area is very large, search efficiency may be greatly reduced if only one robot searches an entire region given the limited resources available and time constraints. In this research we divided the entire search area into several subregions, selected a target utility function to determine which subregion should be initially searched and thereby reduced the residence time of the target to improve search efficiency.

  17. Precise regional baseline estimation using a priori orbital information

    NASA Technical Reports Server (NTRS)

    Lindqwister, Ulf J.; Lichten, Stephen M.; Blewitt, Geoffrey

    1990-01-01

    A solution using GPS measurements acquired during the CASA Uno campaign has resulted in 3-4 mm horizontal daily baseline repeatability and 13 mm vertical repeatability for a 729 km baseline, located in North America. The agreement with VLBI is at the level of 10-20 mm for all components. The results were obtained with the GIPSY orbit determination and baseline estimation software and are based on five single-day data arcs spanning the 20, 21, 25, 26, and 27 of January, 1988. The estimation strategy included resolving the carrier phase integer ambiguities, utilizing an optial set of fixed reference stations, and constraining GPS orbit parameters by applying a priori information. A multiday GPS orbit and baseline solution has yielded similar 2-4 mm horizontal daily repeatabilities for the same baseline, consistent with the constrained single-day arc solutions. The application of weak constraints to the orbital state for single-day data arcs produces solutions which approach the precise orbits obtained with unconstrained multiday arc solutions.

  18. Microwave Radar Imaging of Heterogeneous Breast Tissue Integrating A Priori Information

    PubMed Central

    Kelly, Thomas N.; Sarafianou, Mantalena; Craddock, Ian J.

    2014-01-01

    Conventional radar-based image reconstruction techniques fail when they are applied to heterogeneous breast tissue, since the underlying in-breast relative permittivity is unknown or assumed to be constant. This results in a systematic error during the process of image formation. A recent trend in microwave biomedical imaging is to extract the relative permittivity from the object under test to improve the image reconstruction quality and thereby to enhance the diagnostic assessment. In this paper, we present a novel radar-based methodology for microwave breast cancer detection in heterogeneous breast tissue integrating a 3D map of relative permittivity as a priori information. This leads to a novel image reconstruction formulation where the delay-and-sum focusing takes place in time rather than range domain. Results are shown for a heterogeneous dense (class-4) and a scattered fibroglandular (class-2) numerical breast phantom using Bristol's 31-element array configuration. PMID:25435861

  19. A Hybrid Search Algorithm for Swarm Robots Searching in an Unknown Environment

    PubMed Central

    Li, Shoutao; Li, Lina; Lee, Gordon; Zhang, Hao

    2014-01-01

    This paper proposes a novel method to improve the efficiency of a swarm of robots searching in an unknown environment. The approach focuses on the process of feeding and individual coordination characteristics inspired by the foraging behavior in nature. A predatory strategy was used for searching; hence, this hybrid approach integrated a random search technique with a dynamic particle swarm optimization (DPSO) search algorithm. If a search robot could not find any target information, it used a random search algorithm for a global search. If the robot found any target information in a region, the DPSO search algorithm was used for a local search. This particle swarm optimization search algorithm is dynamic as all the parameters in the algorithm are refreshed synchronously through a communication mechanism until the robots find the target position, after which, the robots fall back to a random searching mode. Thus, in this searching strategy, the robots alternated between two searching algorithms until the whole area was covered. During the searching process, the robots used a local communication mechanism to share map information and DPSO parameters to reduce the communication burden and overcome hardware limitations. If the search area is very large, search efficiency may be greatly reduced if only one robot searches an entire region given the limited resources available and time constraints. In this research we divided the entire search area into several subregions, selected a target utility function to determine which subregion should be initially searched and thereby reduced the residence time of the target to improve search efficiency. PMID:25386855

  20. Impact of modellers' decisions on hydrological a priori predictions

    NASA Astrophysics Data System (ADS)

    Holländer, H. M.; Bormann, H.; Blume, T.; Buytaert, W.; Chirico, G. B.; Exbrayat, J.-F.; Gustafsson, D.; Hölzel, H.; Krauße, T.; Kraft, P.; Stoll, S.; Blöschl, G.; Flühler, H.

    2013-07-01

    The purpose of this paper is to stimulate a re-thinking of how we, the catchment hydrologists, could become reliable forecasters. A group of catchment modellers predicted the hydrological response of a man-made 6 ha catchment in its initial phase (Chicken Creek) without having access to the observed records. They used conceptually different model families. Their modelling experience differed largely. The prediction exercise was organized in three steps: (1) for the 1st prediction modellers received a basic data set describing the internal structure of the catchment (somewhat more complete than usually available to a priori predictions in ungauged catchments). They did not obtain time series of stream flow, soil moisture or groundwater response. (2) Before the 2nd improved prediction they inspected the catchment on-site and attended a workshop where the modellers presented and discussed their first attempts. (3) For their improved 3rd prediction they were offered additional data by charging them pro forma with the costs for obtaining this additional information. Holländer et al. (2009) discussed the range of predictions obtained in step 1. Here, we detail the modeller's decisions in accounting for the various processes based on what they learned during the field visit (step 2) and add the final outcome of step 3 when the modellers made use of additional data. We document the prediction progress as well as the learning process resulting from the availability of added information. For the 2nd and 3rd step, the progress in prediction quality could be evaluated in relation to individual modelling experience and costs of added information. We learned (i) that soft information such as the modeller's system understanding is as important as the model itself (hard information), (ii) that the sequence of modelling steps matters (field visit, interactions between differently experienced experts, choice of model, selection of available data, and methods for parameter guessing

  1. Impact of modellers' decisions on hydrological a priori predictions

    NASA Astrophysics Data System (ADS)

    Holländer, H. M.; Bormann, H.; Blume, T.; Buytaert, W.; Chirico, G. B.; Exbrayat, J.-F.; Gustafsson, D.; Hölzel, H.; Krauße, T.; Kraft, P.; Stoll, S.; Blöschl, G.; Flühler, H.

    2014-06-01

    In practice, the catchment hydrologist is often confronted with the task of predicting discharge without having the needed records for calibration. Here, we report the discharge predictions of 10 modellers - using the model of their choice - for the man-made Chicken Creek catchment (6 ha, northeast Germany, Gerwin et al., 2009b) and we analyse how well they improved their prediction in three steps based on adding information prior to each following step. The modellers predicted the catchment's hydrological response in its initial phase without having access to the observed records. They used conceptually different physically based models and their modelling experience differed largely. Hence, they encountered two problems: (i) to simulate discharge for an ungauged catchment and (ii) using models that were developed for catchments, which are not in a state of landscape transformation. The prediction exercise was organized in three steps: (1) for the first prediction the modellers received a basic data set describing the catchment to a degree somewhat more complete than usually available for a priori predictions of ungauged catchments; they did not obtain information on stream flow, soil moisture, nor groundwater response and had therefore to guess the initial conditions; (2) before the second prediction they inspected the catchment on-site and discussed their first prediction attempt; (3) for their third prediction they were offered additional data by charging them pro forma with the costs for obtaining this additional information. Holländer et al. (2009) discussed the range of predictions obtained in step (1). Here, we detail the modeller's assumptions and decisions in accounting for the various processes. We document the prediction progress as well as the learning process resulting from the availability of added information. For the second and third steps, the progress in prediction quality is evaluated in relation to individual modelling experience and costs of

  2. The consequences of learnability for the a priori knowledge in a world

    NASA Astrophysics Data System (ADS)

    Sommer, Hanns

    1998-07-01

    The precondition for the evolution of intelligent beings in a world (modelled by anticipatory systems) is the learnability of some regularities in that world. The consequences, that can be deduced from the learnability property in a world, form the a priori knowledge. This a priori knowledge is independent of the empirical facts in a special world. It will be shown that the a priori knowledge consists not only of logical tautologies. Also some well-known non trivial theorems in physics and psychology form part of the a priori knowledge. The a priori knowledge obtained in different worlds is necessarily organised by the same structures. Examples from physics and psychology show the use of a separation between a priori knowledge and empirical knowledge.

  3. Exploration of Unknown Spaces by People Who Are Blind Using a Multi-sensory Virtual Environment

    ERIC Educational Resources Information Center

    Lahav, Orly; Mioduser, David

    2004-01-01

    The ability to explore unknown spaces independently, safely and efficiently is a combined product of motor, sensory, and cognitive skills. Normal exercise of this ability directly affects an individual?s quality of life. Mental mapping of spaces and of the possible paths for navigating these spaces is essential for the development of efficient…

  4. Validating Affordances as an Instrument for Design and a Priori Analysis of Didactical Situations in Mathematics

    ERIC Educational Resources Information Center

    Sollervall, Håkan; Stadler, Erika

    2015-01-01

    The aim of the presented case study is to investigate how coherent analytical instruments may guide the a priori and a posteriori analyses of a didactical situation. In the a priori analysis we draw on the notion of affordances, as artefact-mediated opportunities for action, to construct hypothetical trajectories of goal-oriented actions that have…

  5. Reaction norm model with unknown environmental covariate to analyze heterosis by environment interaction.

    PubMed

    Su, G; Madsen, P; Lund, M S

    2009-05-01

    Crossbreeding is currently increasing in dairy cattle production. Several studies have shown an environment-dependent heterosis [i.e., an interaction between heterosis and environment (H x E)]. An H x E interaction is usually estimated from a few discrete environment levels. The present study proposes a reaction norm model to describe H x E interaction, which can deal with a large number of environment levels using few parameters. In the proposed model, total heterosis consists of an environment-independent part, which is described as a function of heterozygosity, and an environment-dependent part, which is described as a function of heterozygosity and environmental value (e.g., herd-year effect). A Bayesian approach is developed to estimate the environmental covariates, the regression coefficients of the reaction norm, and other parameters of the model simultaneously in both linear and nonlinear reaction norms. In the nonlinear reaction norm model, the H x E is approximated using linear splines. The approach was tested using simulated data, which were generated using an animal model with a reaction norm for heterosis. The simulation study includes 4 scenarios (the combinations of moderate vs. low heritability and moderate vs. low herd-year variation) of H x E interaction in a nonlinear form. In all scenarios, the proposed model predicted total heterosis very well. The correlation between true heterosis and predicted heterosis was 0.98 in the scenarios with low herd-year variation and 0.99 in the scenarios with moderate herd-year variation. This suggests that the proposed model and method could be a good approach to analyze H x E interactions and predict breeding values in situations in which heterosis changes gradually and continuously over an environmental gradient. On the other hand, it was found that a model ignoring H x E interaction did not significantly harm the prediction of breeding value under the simulated scenarios in which the variance for environment

  6. SLAM algorithm applied to robotics assistance for navigation in unknown environments.

    PubMed

    Cheein, Fernando A Auat; Lopez, Natalia; Soria, Carlos M; di Sciascio, Fernando A; Pereira, Fernando Lobo; Carelli, Ricardo

    2010-02-17

    The combination of robotic tools with assistance technology determines a slightly explored area of applications and advantages for disability or elder people in their daily tasks. Autonomous motorized wheelchair navigation inside an environment, behaviour based control of orthopaedic arms or user's preference learning from a friendly interface are some examples of this new field. In this paper, a Simultaneous Localization and Mapping (SLAM) algorithm is implemented to allow the environmental learning by a mobile robot while its navigation is governed by electromyographic signals. The entire system is part autonomous and part user-decision dependent (semi-autonomous). The environmental learning executed by the SLAM algorithm and the low level behaviour-based reactions of the mobile robot are robotic autonomous tasks, whereas the mobile robot navigation inside an environment is commanded by a Muscle-Computer Interface (MCI). In this paper, a sequential Extended Kalman Filter (EKF) feature-based SLAM algorithm is implemented. The features correspond to lines and corners -concave and convex- of the environment. From the SLAM architecture, a global metric map of the environment is derived. The electromyographic signals that command the robot's movements can be adapted to the patient's disabilities. For mobile robot navigation purposes, five commands were obtained from the MCI: turn to the left, turn to the right, stop, start and exit. A kinematic controller to control the mobile robot was implemented. A low level behavior strategy was also implemented to avoid robot's collisions with the environment and moving agents. The entire system was tested in a population of seven volunteers: three elder, two below-elbow amputees and two young normally limbed patients. The experiments were performed within a closed low dynamic environment. Subjects took an average time of 35 minutes to navigate the environment and to learn how to use the MCI. The SLAM results have shown a

  7. SLAM algorithm applied to robotics assistance for navigation in unknown environments

    PubMed Central

    2010-01-01

    Background The combination of robotic tools with assistance technology determines a slightly explored area of applications and advantages for disability or elder people in their daily tasks. Autonomous motorized wheelchair navigation inside an environment, behaviour based control of orthopaedic arms or user's preference learning from a friendly interface are some examples of this new field. In this paper, a Simultaneous Localization and Mapping (SLAM) algorithm is implemented to allow the environmental learning by a mobile robot while its navigation is governed by electromyographic signals. The entire system is part autonomous and part user-decision dependent (semi-autonomous). The environmental learning executed by the SLAM algorithm and the low level behaviour-based reactions of the mobile robot are robotic autonomous tasks, whereas the mobile robot navigation inside an environment is commanded by a Muscle-Computer Interface (MCI). Methods In this paper, a sequential Extended Kalman Filter (EKF) feature-based SLAM algorithm is implemented. The features correspond to lines and corners -concave and convex- of the environment. From the SLAM architecture, a global metric map of the environment is derived. The electromyographic signals that command the robot's movements can be adapted to the patient's disabilities. For mobile robot navigation purposes, five commands were obtained from the MCI: turn to the left, turn to the right, stop, start and exit. A kinematic controller to control the mobile robot was implemented. A low level behavior strategy was also implemented to avoid robot's collisions with the environment and moving agents. Results The entire system was tested in a population of seven volunteers: three elder, two below-elbow amputees and two young normally limbed patients. The experiments were performed within a closed low dynamic environment. Subjects took an average time of 35 minutes to navigate the environment and to learn how to use the MCI. The SLAM

  8. Optimal quantum cloning based on the maximin principle by using a priori information

    NASA Astrophysics Data System (ADS)

    Kang, Peng; Dai, Hong-Yi; Wei, Jia-Hua; Zhang, Ming

    2016-10-01

    We propose an optimal 1 →2 quantum cloning method based on the maximin principle by making full use of a priori information of amplitude and phase about the general cloned qubit input set, which is a simply connected region enclosed by a "longitude-latitude grid" on the Bloch sphere. Theoretically, the fidelity of the optimal quantum cloning machine derived from this method is the largest in terms of the maximin principle compared with that of any other machine. The problem solving is an optimization process that involves six unknown complex variables, six vectors in an uncertain-dimensional complex vector space, and four equality constraints. Moreover, by restricting the structure of the quantum cloning machine, the optimization problem is simplified as a three-real-parameter suboptimization problem with only one equality constraint. We obtain the explicit formula for a suboptimal quantum cloning machine. Additionally, the fidelity of our suboptimal quantum cloning machine is higher than or at least equal to that of universal quantum cloning machines and phase-covariant quantum cloning machines. It is also underlined that the suboptimal cloning machine outperforms the "belt quantum cloning machine" for some cases.

  9. Unknown object localization and identification in shallow water environment at Lake Balaton

    NASA Astrophysics Data System (ADS)

    Kiss, Balint; Bostater, Charles R., Jr.; Vajda, Ferenc; Vajta, Laszlo; Vogel, Miklos

    2004-11-01

    This paper addresses a particular detection problem related to the largest freshwater lake of Central and Western Europe, namely the Lake Balaton. The bed-silt of this shallow water lake (its average depth is 3.3 meters) contains several type of objects: industrial debris, historical vestiges, and in particular, an unknown quantity of unexploded ordnance from the second World War. It is important to localize and classify these objects for precise risk assessment and eventual later removal (not addressed in the paper). The bed-silt of the lake can be characterized as a mud having a light and constantly changing structure. It follows that the shallow water is almost always mixed with the mud. This admixture is constantly maintained by winds and navigating boats, hence the underwater visibility is close to zero during the most part of the year, especially in the depth range close to the bottom. Since the climate makes it possible, the authors propose a special way to explore the bed-silt of the lake, namely the use an autonomous vehicle on the frozen lake. Note that the ice prevents the wind and navigating boats to generate water movement and thus the mud is sedimented. This autonomous vehicle is equipped with a GPS based onboard localization system, with multiple sensor and recording equipment, and with a radio link to its command post. More details about the nature of objects to be detected as well as about the architecture of the detection and localization system are presented in the paper.

  10. Searching for 'Unknown Unknowns'

    NASA Technical Reports Server (NTRS)

    Parsons, Vickie S.

    2005-01-01

    The NASA Engineering and Safety Center (NESC) was established to improve safety through engineering excellence within NASA programs and projects. As part of this goal, methods are being investigated to enable the NESC to become proactive in identifying areas that may be precursors to future problems. The goal is to find unknown indicators of future problems, not to duplicate the program-specific trending efforts. The data that is critical for detecting these indicators exist in a plethora of dissimilar non-conformance and other databases (without a common format or taxonomy). In fact, much of the data is unstructured text. However, one common database is not required if the right standards and electronic tools are employed. Electronic data mining is a particularly promising tool for this effort into unsupervised learning of common factors. This work in progress began with a systematic evaluation of available data mining software packages, based on documented decision techniques using weighted criteria. The four packages, which were perceived to have the most promise for NASA applications, are being benchmarked and evaluated by independent contractors. Preliminary recommendations for "best practices" in data mining and trending are provided. Final results and recommendations should be available in the Fall 2005. This critical first step in identifying "unknown unknowns" before they become problems is applicable to any set of engineering or programmatic data.

  11. Use of a priori statistics to minimize acquisition time for RFI immune spread spectrum systems

    NASA Technical Reports Server (NTRS)

    Holmes, J. K.; Woo, K. T.

    1978-01-01

    The optimum acquisition sweep strategy was determined for a PN code despreader when the a priori probability density function was not uniform. A psuedo noise spread spectrum system was considered which could be utilized in the DSN to combat radio frequency interference. In a sample case, when the a priori probability density function was Gaussian, the acquisition time was reduced by about 41% compared to a uniform sweep approach.

  12. On Evaluation of Recharge Model Uncertainty: a Priori and a Posteriori

    SciTech Connect

    Ming Ye; Karl Pohlmann; Jenny Chapman; David Shafer

    2006-01-30

    Hydrologic environments are open and complex, rendering them prone to multiple interpretations and mathematical descriptions. Hydrologic analyses typically rely on a single conceptual-mathematical model, which ignores conceptual model uncertainty and may result in bias in predictions and under-estimation of predictive uncertainty. This study is to assess conceptual model uncertainty residing in five recharge models developed to date by different researchers based on different theories for Nevada and Death Valley area, CA. A recently developed statistical method, Maximum Likelihood Bayesian Model Averaging (MLBMA), is utilized for this analysis. In a Bayesian framework, the recharge model uncertainty is assessed, a priori, using expert judgments collected through an expert elicitation in the form of prior probabilities of the models. The uncertainty is then evaluated, a posteriori, by updating the prior probabilities to estimate posterior model probability. The updating is conducted through maximum likelihood inverse modeling by calibrating the Death Valley Regional Flow System (DVRFS) model corresponding to each recharge model against observations of head and flow. Calibration results of DVRFS for the five recharge models are used to estimate three information criteria (AIC, BIC, and KIC) used to rank and discriminate these models. Posterior probabilities of the five recharge models, evaluated using KIC, are used as weights to average head predictions, which gives posterior mean and variance. The posterior quantities incorporate both parametric and conceptual model uncertainties.

  13. A priori data-driven multi-clustered reservoir generation algorithm for echo state network.

    PubMed

    Li, Xiumin; Zhong, Ling; Xue, Fangzheng; Zhang, Anguo

    2015-01-01

    Echo state networks (ESNs) with multi-clustered reservoir topology perform better in reservoir computing and robustness than those with random reservoir topology. However, these ESNs have a complex reservoir topology, which leads to difficulties in reservoir generation. This study focuses on the reservoir generation problem when ESN is used in environments with sufficient priori data available. Accordingly, a priori data-driven multi-cluster reservoir generation algorithm is proposed. The priori data in the proposed algorithm are used to evaluate reservoirs by calculating the precision and standard deviation of ESNs. The reservoirs are produced using the clustering method; only the reservoir with a better evaluation performance takes the place of a previous one. The final reservoir is obtained when its evaluation score reaches the preset requirement. The prediction experiment results obtained using the Mackey-Glass chaotic time series show that the proposed reservoir generation algorithm provides ESNs with extra prediction precision and increases the structure complexity of the network. Further experiments also reveal the appropriate values of the number of clusters and time window size to obtain optimal performance. The information entropy of the reservoir reaches the maximum when ESN gains the greatest precision.

  14. Reconstruction of Consistent 3d CAD Models from Point Cloud Data Using a Priori CAD Models

    NASA Astrophysics Data System (ADS)

    Bey, A.; Chaine, R.; Marc, R.; Thibault, G.; Akkouche, S.

    2011-09-01

    We address the reconstruction of 3D CAD models from point cloud data acquired in industrial environments, using a pre-existing 3D model as an initial estimate of the scene to be processed. Indeed, this prior knowledge can be used to drive the reconstruction so as to generate an accurate 3D model matching the point cloud. We more particularly focus our work on the cylindrical parts of the 3D models. We propose to state the problem in a probabilistic framework: we have to search for the 3D model which maximizes some probability taking several constraints into account, such as the relevancy with respect to the point cloud and the a priori 3D model, and the consistency of the reconstructed model. The resulting optimization problem can then be handled using a stochastic exploration of the solution space, based on the random insertion of elements in the configuration under construction, coupled with a greedy management of the conflicts which efficiently improves the configuration at each step. We show that this approach provides reliable reconstructed 3D models by presenting some results on industrial data sets.

  15. Conventional Principles in Science: On the foundations and development of the relativized a priori

    NASA Astrophysics Data System (ADS)

    Ivanova, Milena; Farr, Matt

    2015-11-01

    The present volume consists of a collection of papers originally presented at the conference Conventional Principles in Science, held at the University of Bristol, August 2011, which featured contributions on the history and contemporary development of the notion of 'relativized a priori' principles in science, from Henri Poincaré's conventionalism to Michael Friedman's contemporary defence of the relativized a priori. In Science and Hypothesis, Poincaré assessed the problematic epistemic status of Euclidean geometry and Newton's laws of motion, famously arguing that each has the status of 'convention' in that their justification is neither analytic nor empirical in nature. In The Theory of Relativity and A Priori Knowledge, Hans Reichenbach, in light of the general theory of relativity, proposed an updated notion of the Kantian synthetic a priori to account for the dynamic inter-theoretic status of geometry and other non-empirical physical principles. Reichenbach noted that one may reject the 'necessarily true' aspect of the synthetic a priori whilst preserving the feature of being constitutive of the object of knowledge. Such constitutive principles are theory-relative, as illustrated by the privileged role of non-Euclidean geometry in general relativity theory. This idea of relativized a priori principles in spacetime physics has been analysed and developed at great length in the modern literature in the work of Michael Friedman, in particular the roles played by the light postulate and the equivalence principle - in special and general relativity respectively - in defining the central terms of their respective theories and connecting the abstract mathematical formalism of the theories with their empirical content. The papers in this volume guide the reader through the historical development of conventional and constitutive principles in science, from the foundational work of Poincaré, Reichenbach and others, to contemporary issues and applications of the

  16. The constitutive a priori and the distinction between mathematical and physical possibility

    NASA Astrophysics Data System (ADS)

    Everett, Jonathan

    2015-11-01

    This paper is concerned with Friedman's recent revival of the notion of the relativized a priori. It is particularly concerned with addressing the question as to how Friedman's understanding of the constitutive function of the a priori has changed since his defence of the idea in his Dynamics of Reason. Friedman's understanding of the a priori remains influenced by Reichenbach's initial defence of the idea; I argue that this notion of the a priori does not naturally lend itself to describing the historical development of space-time physics. Friedman's analysis of the role of the rotating frame thought experiment in the development of general relativity - which he suggests made the mathematical possibility of four-dimensional space-time a genuine physical possibility - has a central role in his argument. I analyse this thought experiment and argue that it is better understood by following Cassirer and placing emphasis on regulative principles. Furthermore, I argue that Cassirer's Kantian framework enables us to capture Friedman's key insights into the nature of the constitutive a priori.

  17. A priori identifiability of a one-compartment model with two input functions for liver blood flow measurements

    NASA Astrophysics Data System (ADS)

    Becker, Georg A.; Müller-Schauenburg, Wolfgang; Spilker, Mary E.; Machulla, Hans-Jürgen; Piert, Morand

    2005-04-01

    An extended dual-input Kety-Schmidt model can be applied to positron emission tomography data for the quantification of local arterial (fa) and local portal-venous blood flow (fp) in the liver by freely diffusible tracers (e.g., [15O]H2O). We investigated the a priori identifiability of the three-parameter model (fa, fp and distribution volume (Vd)) under ideal (noise-free) conditions. The results indicate that the full identifiability of the model depends on the form of the portal-venous input function (cp(t)), which is assumed to be a sum of m exponentials convolved with the arterial input function (ca(t)). When m >= 2, all three-model parameters are uniquely identifiable. For m = 1 identifiability of fp fails if cp(t) coincides with tissue concentration (q(t)/Vd), which occurs if cp(t) is generated from an intestinal compartment with transit time Vd/fa. Any portal input, fp cp(t), is balanced by the portal contribution, fp q(t)/Vd, to the liver efflux, leaving q(t) unchanged by fp and only fa and Vd are a priori uniquely identifiable. An extension to this condition of unidentifiability is obtained if we leave the assumption of a generating intestinal compartment system and allow for an arbitrary proportionality constant between cp(t) and q(t). In this case, only fa remains a priori uniquely identifiable. These findings provide important insights into the behaviour and identifiability of the model applied to the unique liver environment.

  18. Mediterranean Diet and Cardiovascular Disease: A Critical Evaluation of A Priori Dietary Indexes

    PubMed Central

    D’Alessandro, Annunziata; De Pergola, Giovanni

    2015-01-01

    The aim of this paper is to analyze the a priori dietary indexes used in the studies that have evaluated the role of the Mediterranean Diet in influencing the risk of developing cardiovascular disease. All the studies show that this dietary pattern protects against cardiovascular disease, but studies show quite different effects on specific conditions such as coronary heart disease or cerebrovascular disease. A priori dietary indexes used to measure dietary exposure imply quantitative and/or qualitative divergences from the traditional Mediterranean Diet of the early 1960s, and, therefore, it is very difficult to compare the results of different studies. Based on real cultural heritage and traditions, we believe that the a priori indexes used to evaluate adherence to the Mediterranean Diet should consider classifying whole grains and refined grains, olive oil and monounsaturated fats, and wine and alcohol differently. PMID:26389950

  19. Bayesian classification of polarimetric SAR images using adaptive a priori probabilities

    NASA Technical Reports Server (NTRS)

    Van Zyl, J. J.; Burnette, C. F.

    1992-01-01

    The problem of classifying earth terrain by observed polarimetric scattering properties is tackled with an iterative Bayesian scheme using a priori probabilities adaptively. The first classification is based on the use of fixed and not necessarily equal a priori probabilities, and successive iterations change the a priori probabilities adaptively. The approach is applied to an SAR image in which a single water body covers 10 percent of the image area. The classification accuracy for ocean, urban, vegetated, and total area increase, and the percentage of reclassified pixels decreases greatly as the iteration number increases. The iterative scheme is found to improve the a posteriori classification accuracy of maximum likelihood classifiers by iteratively using the local homogeneity in polarimetric SAR images. A few iterations can improve the classification accuracy significantly without sacrificing key high-frequency detail or edges in the image.

  20. Incorporation of a priori gravity field information in satellite orbit determination using bin parameters

    NASA Technical Reports Server (NTRS)

    Wu, Jiun-Tsong; Wu, Sien-Chong

    1992-01-01

    A method to determine satellite orbits using tracking data and a priori gravitational field is described. The a priori constraint on the orbit dynamics is determined by the covariance matrix of the spherical harmonic coefficients for the gravity model, so that the optimal combination of the measurements and gravitational field is achieved. A set of bin parameters is introduced to represent the perturbation of the gravitational field on the position of the satellite orbit. The covariance matrix of a conventional gravity model is transformed into that for the bin parameters by the variational partial derivatives. The covariance matrices of the bin parameters and the epoch state are combined to form the covariance matrix of the satellite positions at the measurement times. The combined matrix is used as the a priori information to estimate the satellite positions with measurements.

  1. Bayesian classification of polarimetric SAR images using adaptive a priori probabilities

    NASA Technical Reports Server (NTRS)

    Van Zyl, J. J.; Burnette, C. F.

    1992-01-01

    The problem of classifying earth terrain by observed polarimetric scattering properties is tackled with an iterative Bayesian scheme using a priori probabilities adaptively. The first classification is based on the use of fixed and not necessarily equal a priori probabilities, and successive iterations change the a priori probabilities adaptively. The approach is applied to an SAR image in which a single water body covers 10 percent of the image area. The classification accuracy for ocean, urban, vegetated, and total area increase, and the percentage of reclassified pixels decreases greatly as the iteration number increases. The iterative scheme is found to improve the a posteriori classification accuracy of maximum likelihood classifiers by iteratively using the local homogeneity in polarimetric SAR images. A few iterations can improve the classification accuracy significantly without sacrificing key high-frequency detail or edges in the image.

  2. Incorporation of a priori gravity field information in satellite orbit determination using bin parameters

    NASA Technical Reports Server (NTRS)

    Wu, Jiun-Tsong; Wu, Sien-Chong

    1992-01-01

    A method to determine satellite orbits using tracking data and a priori gravitational field is described. The a priori constraint on the orbit dynamics is determined by the covariance matrix of the spherical harmonic coefficients for the gravity model, so that the optimal combination of the measurements and gravitational field is achieved. A set of bin parameters is introduced to represent the perturbation of the gravitational field on the position of the satellite orbit. The covariance matrix of a conventional gravity model is transformed into that for the bin parameters by the variational partial derivatives. The covariance matrices of the bin parameters and the epoch state are combined to form the covariance matrix of the satellite positions at the measurement times. The combined matrix is used as the a priori information to estimate the satellite positions with measurements.

  3. Allocating Sample Material to Increase the Precision of a Priori Contrasts.

    ERIC Educational Resources Information Center

    Clark, Sheldon B.; Huck, Schuyler W.

    In true experiments in which sample material can be randomly assigned to treatment conditions, most researchers presume that the condition of equal sample sizes is statistically desirable. When one or more a priori contrasts can be identified which represent a few overriding experimental concerns, however, allocating sample material unequally will…

  4. Simplified multi-track detection schemes using a priori information for bit patterned media recording

    NASA Astrophysics Data System (ADS)

    Kong, Gyuyeol; Choi, Sooyong

    2012-04-01

    Simplified multi-track detection schemes using a priori information for bit patterned magnetic recording (BPMR) are proposed in this paper. The proposed detection schemes adopt the simplified trellis diagram, use a priori information, and detect the main-track data in the along- and cross-track directions. The simplified trellis diagram, which has 4 states and 8 branches, can be obtained by setting the corner entries of the generalized partial response (GPR) target to zero and replacing the four parallel branches with a single branch. However, these simplified techniques seriously suffer from performance degradation in high density BPMR channels. To overcome the performance degradation, a priori information is used to give higher reliability to the branch metric. In addition, to fully use the characteristics of channel detection with a two-dimensional (2D) GPR target, the proposed schemes estimate a priori information and detect the main-track data in the along- and cross-track directions by using a 2D equalizer with a 2D GPR target. The bit error rate performances of the proposed schemes are compared with the previous detection schemes when areal density is 3 Tb/in2. Simulation results show that the proposed schemes with simpler structures have more than 2 dB gains compared with the other detection schemes.

  5. Background and Attitude Questionnaire Items and A Priori Weights. Table 4.

    ERIC Educational Resources Information Center

    Michigan State Dept. of Education, Lansing. Research, Evaluation, and Assessment Services.

    Background and attitude questionnaire items used in the Michigan Educational Assessment battery to measure socioeconomic status and attitudes toward self, school, and the importance of school achievement are presented. A priori weights for item responses are provided. (For related document, see TM 002 329.) (KM)

  6. A priori L∞ estimates for solutions of a class of reaction-diffusion systems.

    PubMed

    Du, Zengji; Peng, Rui

    2016-05-01

    In this short paper, we establish a priori L∞-norm estimates for solutions of a class of reaction-diffusion systems which can be used to model the spread of infectious disease. The developed technique may find applications in other reaction-diffusion systems.

  7. Unequal a priori probability multiple hypothesis testing in space domain awareness with the space surveillance telescope.

    PubMed

    Hardy, Tyler; Cain, Stephen; Blake, Travis

    2016-05-20

    This paper investigates the ability to improve Space Domain Awareness (SDA) by increasing the number of detectable Resident Space Objects (RSOs) from space surveillance sensors. With matched filter based techniques, the expected impulse response, or Point Spread Function (PSF), is compared against the received data. In the situation where the images are spatially undersampled, the modeled PSF may not match the received data if the RSO does not fall in the center of the pixel. This aliasing can be accounted for with a Multiple Hypothesis Test (MHT). Previously, proposed MHTs have implemented a test with an equal a priori prior probability assumption. This paper investigates using an unequal a priori probability MHT. To determine accurate a priori probabilities, three metrics are computed; they are correlation, physical distance, and empirical. Using the calculated a priori probabilities, a new algorithm is developed, and images from the Space Surveillance Telescope (SST) are analyzed. The number of detected objects by both an equal and unequal prior probabilities are compared while keeping the false alarm rate constant. Any additional number of detected objects will help improve SDA capabilities.

  8. Realism, functions, and the a priori: Ernst Cassirer's philosophy of science.

    PubMed

    Heis, Jeremy

    2014-12-01

    This paper presents the main ideas of Cassirer's general philosophy of science, focusing on the two aspects of his thought that--in addition to being the most central ideas in his philosophy of science--have received the most attention from contemporary philosophers of science: his theory of the a priori aspects of physical theory, and his relation to scientific realism.

  9. Integration of 3D and 2D imaging data for assured navigation in unknown environments: initial steps

    NASA Astrophysics Data System (ADS)

    Dill, Evan; Uijt de Haag, Maarten

    2009-05-01

    This paper discusses the initial steps of the development of a novel navigation method that integrates three-dimensional (3D) point cloud data, two-dimensional (2D) gray-level (intensity), and data from an Inertial Measurement Unit (IMU). A time-of-flight camera such as MESA's Swissranger will output both the 3D and 2D data. The target application is position and attitude determination of unmanned aerial vehicles (UAV) and autonomous ground vehicles (AGV) in urban or indoor environments. In urban and indoor environments a GPS position capability may not only be unavailable due to shadowing, significant signal attenuation or multipath, but also due to intentional denial or deception. The proposed algorithm extracts key features such as planar surfaces, lines and corner-points from both the 3D (point-cloud) and 2D (intensity) imagery. Consecutive observations of corresponding features in the 3D and 2D image frames are then used to compute estimates of position and orientation changes. Since the use of 3D image features for positioning suffers from limited feature observability resulting in deteriorated position accuracies, and the 2D imagery suffers from an unknown depth when estimating the pose from consecutive image frames, it is expected that the integration of both data sets will alleviate the problems with the individual methods resulting in an position and attitude determination method with a high level of assurance. An Inertial Measurement Unit (IMU) is used to set up the tracking gates necessary to perform data association of the features in consecutive frames. Finally, the position and orientation change estimates can be used to correct for the IMU drift errors.

  10. Aerial vehicle navigation over unknown terrain environments using inertial measurements and dual airborne laser scanners or flash ladar

    NASA Astrophysics Data System (ADS)

    Vadlamani, Ananth K.; Uijt de Haag, Maarten

    2007-04-01

    A precise navigation system for uninhabited or inhabited aerial vehicles is discussed in this paper. The navigational capability of an aerial vehicle must be robust and not easily influenced by external factors. Nowadays, many navigation systems rely somehow on the Global Positioning System (GPS), wherein the GPS signals may be rendered unusable due to unintentional interference caused by atmospheric effects, interference from communication equipment, as well as intentional jamming. The navigation method discussed in this paper integrates measurements from an Inertial Measurement Unit (IMU) with measurements from either two airborne laser scanners (ALS) or an airborne Flash LADAR (AFL) to provide autonomous navigational capability and a reliable alternative to GPS. The proposed system has applications in unknown or partially known terrain environments or it may also be used for autonomous landing systems in Lunar or Martian environments. Two approaches are described in this paper, one approach uses Dual Airborne Laser Scanners (DALS) (one pointing forward, the other pointing aft) and the other approach uses an AFL. Advantages and disadvantages of both approaches are discussed. The proposed navigation system uses strapdown IMU measurements to estimate the aerial vehicle position and attitude and to geo-reference the laser sensor data. It then uses the maps created from both the fore and aftpointing scanning LADARS or the consecutive Flash LADAR range-images to estimate systematic IMU errors such as position and velocity drifts. The proposed navigation algorithm is evaluated using flight test data from Ohio University's DC3 aircraft and synthesized ALS and AFL measurements. Initial results are observed to achieve meter level accuracies in the system's position drift performance.

  11. A priori estimates, existence and non-existence for quasilinear cooperative elliptic systems

    SciTech Connect

    Zou, H

    2008-04-30

    Let m>1 be a real number and let {omega} subset of R{sup n}, n>=2, be a connected smooth domain. Consider the system of quasi-linear elliptic differential equations ; div(|{nabla}u|{sup m-2}{nabla}u)+f(u,v); =0 in {omega}; div(|{nabla}v|{sup m-2}{nabla}v)+g(u,v); =0 in {omega}; where u>=0, v>=0, f and g are real functions. Relations between the Liouville non-existence and a priori estimates and existence on bounded domains are studied. Under appropriate conditions, a variety of results on a priori estimates, existence and non-existence of positive solutions have been established. Bibliography: 11 titles.

  12. A priori Estimates and Existence for Elliptic Systems via Bootstrap in Weighted Lebesgue Spaces

    NASA Astrophysics Data System (ADS)

    Quittner, P.; Souplet, Ph.

    2004-10-01

    We present a new general method to obtain regularity and a priori estimates for solutions of semilinear elliptic systems in bounded domains. This method is based on a bootstrap procedure, used alternatively on each component, in the scale of weighted Lebesgue spaces Lpδ(Ω)=Lp(Ωδ(x) dx), where δ(x) is the distance to the boundary. Using this method, we significantly improve the known existence results for various classes of elliptic systems.

  13. Implications of genome wide association studies for addiction: Are our a priori assumptions all wrong?

    PubMed Central

    Hall, F. Scott; Drgonova, Jana; Jain, Siddharth; Uhl, George R.

    2013-01-01

    Substantial genetic contributions to addiction vulnerability are supported by data from twin studies, linkage studies, candidate gene association studies and, more recently, Genome Wide Association Studies (GWAS). Parallel to this work, animal studies have attempted to identify the genes that may contribute to responses to addictive drugs and addiction liability, initially focusing upon genes for the targets of the major drugs of abuse. These studies identified genes/proteins that affect responses to drugs of abuse; however, this does not necessarily mean that variation in these genes contributes to the genetic component of addiction liability. One of the major problems with initial linkage and candidate gene studies was an a priori focus on the genes thought to be involved in addiction based upon the known contributions of those proteins to drug actions, making the identification of novel genes unlikely. The GWAS approach is systematic and agnostic to such a priori assumptions. From the numerous GWAS now completed several conclusions may be drawn: (1) addiction is highly polygenic; each allelic variant contributing in a small, additive fashion to addiction vulnerability; (2) unexpected, compared to our a priori assumptions, classes of genes are most important in explaining addiction vulnerability; (3) although substantial genetic heterogeneity exists, there is substantial convergence of GWAS signals on particular genes. This review traces the history of this research; from initial transgenic mouse models based upon candidate gene and linkage studies, through the progression of GWAS for addiction and nicotine cessation, to the current human and transgenic mouse studies post-GWAS. PMID:23872493

  14. Effects of daily, high spatial resolution a priori profiles of satellite-derived NOx emissions

    NASA Astrophysics Data System (ADS)

    Laughner, J.; Zare, A.; Cohen, R. C.

    2016-12-01

    The current generation of space-borne NO2 column observations provides a powerful method of constraining NOx emissions due to the spatial resolution and global coverage afforded by the Ozone Monitoring Instrument (OMI). The greater resolution available in next generation instruments such as TROPOMI and the capabilities of geosynchronous platforms TEMPO, Sentinel-4, and GEMS will provide even greater capabilities in this regard, but we must apply lessons learned from the current generation of retrieval algorithms to make the best use of these instruments. Here, we focus on the effect of the resolution of the a priori NO2 profiles used in the retrieval algorithms. We show that for an OMI retrieval, using daily high-resolution a priori profiles results in changes in the retrieved VCDs up to 40% when compared to a retrieval using monthly average profiles at the same resolution. Further, comparing a retrieval with daily high spatial resolution a priori profiles to a more standard one, we show that emissions derived increase by 100% when using the optimized retrieval.

  15. Implications of genome wide association studies for addiction: are our a priori assumptions all wrong?

    PubMed

    Hall, F Scott; Drgonova, Jana; Jain, Siddharth; Uhl, George R

    2013-12-01

    Substantial genetic contributions to addiction vulnerability are supported by data from twin studies, linkage studies, candidate gene association studies and, more recently, Genome Wide Association Studies (GWAS). Parallel to this work, animal studies have attempted to identify the genes that may contribute to responses to addictive drugs and addiction liability, initially focusing upon genes for the targets of the major drugs of abuse. These studies identified genes/proteins that affect responses to drugs of abuse; however, this does not necessarily mean that variation in these genes contributes to the genetic component of addiction liability. One of the major problems with initial linkage and candidate gene studies was an a priori focus on the genes thought to be involved in addiction based upon the known contributions of those proteins to drug actions, making the identification of novel genes unlikely. The GWAS approach is systematic and agnostic to such a priori assumptions. From the numerous GWAS now completed several conclusions may be drawn: (1) addiction is highly polygenic; each allelic variant contributing in a small, additive fashion to addiction vulnerability; (2) unexpected, compared to our a priori assumptions, classes of genes are most important in explaining addiction vulnerability; (3) although substantial genetic heterogeneity exists, there is substantial convergence of GWAS signals on particular genes. This review traces the history of this research; from initial transgenic mouse models based upon candidate gene and linkage studies, through the progression of GWAS for addiction and nicotine cessation, to the current human and transgenic mouse studies post-GWAS.

  16. A priori mesh grading for the numerical calculation of the head-related transfer functions.

    PubMed

    Ziegelwanger, Harald; Kreuzer, Wolfgang; Majdak, Piotr

    2016-12-15

    Head-related transfer functions (HRTFs) describe the directional filtering of the incoming sound caused by the morphology of a listener's head and pinnae. When an accurate model of a listener's morphology exists, HRTFs can be calculated numerically with the boundary element method (BEM). However, the general recommendation to model the head and pinnae with at least six elements per wavelength renders the BEM as a time-consuming procedure when calculating HRTFs for the full audible frequency range. In this study, a mesh preprocessing algorithm is proposed, viz., a priori mesh grading, which reduces the computational costs in the HRTF calculation process significantly. The mesh grading algorithm deliberately violates the recommendation of at least six elements per wavelength in certain regions of the head and pinnae and varies the size of elements gradually according to an a priori defined grading function. The evaluation of the algorithm involved HRTFs calculated for various geometric objects including meshes of three human listeners and various grading functions. The numerical accuracy and the predicted sound-localization performance of calculated HRTFs were analyzed. A-priori mesh grading appeared to be suitable for the numerical calculation of HRTFs in the full audible frequency range and outperformed uniform meshes in terms of numerical errors, perception based predictions of sound-localization performance, and computational costs.

  17. A priori mesh grading for the numerical calculation of the head-related transfer functions

    PubMed Central

    Ziegelwanger, Harald; Kreuzer, Wolfgang; Majdak, Piotr

    2017-01-01

    Head-related transfer functions (HRTFs) describe the directional filtering of the incoming sound caused by the morphology of a listener’s head and pinnae. When an accurate model of a listener’s morphology exists, HRTFs can be calculated numerically with the boundary element method (BEM). However, the general recommendation to model the head and pinnae with at least six elements per wavelength renders the BEM as a time-consuming procedure when calculating HRTFs for the full audible frequency range. In this study, a mesh preprocessing algorithm is proposed, viz., a priori mesh grading, which reduces the computational costs in the HRTF calculation process significantly. The mesh grading algorithm deliberately violates the recommendation of at least six elements per wavelength in certain regions of the head and pinnae and varies the size of elements gradually according to an a priori defined grading function. The evaluation of the algorithm involved HRTFs calculated for various geometric objects including meshes of three human listeners and various grading functions. The numerical accuracy and the predicted sound-localization performance of calculated HRTFs were analyzed. A-priori mesh grading appeared to be suitable for the numerical calculation of HRTFs in the full audible frequency range and outperformed uniform meshes in terms of numerical errors, perception based predictions of sound-localization performance, and computational costs. PMID:28239186

  18. Geopositioning with a quadcopter: Extracted feature locations and predicted accuracy without a priori sensor attitude information

    NASA Astrophysics Data System (ADS)

    Dolloff, John; Hottel, Bryant; Edwards, David; Theiss, Henry; Braun, Aaron

    2017-05-01

    This paper presents an overview of the Full Motion Video-Geopositioning Test Bed (FMV-GTB) developed to investigate algorithm performance and issues related to the registration of motion imagery and subsequent extraction of feature locations along with predicted accuracy. A case study is included corresponding to a video taken from a quadcopter. Registration of the corresponding video frames is performed without the benefit of a priori sensor attitude (pointing) information. In particular, tie points are automatically measured between adjacent frames using standard optical flow matching techniques from computer vision, an a priori estimate of sensor attitude is then computed based on supplied GPS sensor positions contained in the video metadata and a photogrammetric/search-based structure from motion algorithm, and then a Weighted Least Squares adjustment of all a priori metadata across the frames is performed. Extraction of absolute 3D feature locations, including their predicted accuracy based on the principles of rigorous error propagation, is then performed using a subset of the registered frames. Results are compared to known locations (check points) over a test site. Throughout this entire process, no external control information (e.g. surveyed points) is used other than for evaluation of solution errors and corresponding accuracy.

  19. Examples of use of a-priori information to the inversion of AEM data

    NASA Astrophysics Data System (ADS)

    Viezzoli, A.; Munday, T. J.; Sapia, V.

    2012-12-01

    There is a growing focus in the international near surface geophysical community in the merging of information (loosely termed "data") from different sources, in the modelling of the subsurface. The use of a-priori data as extra input to the inversion of Airborne Electromagnetic data is one illustrative example of such trend. It allows providing more robust results, for a number of reasons. The first one is probably the capability to cross check the geophysical derived model against ancillary information, in a more quantitative and objective way than it can be done a-posteriori. The second is that mitigates the inherent non uniqueness of the results of inversion of geophysical data, which is due to the fact that the problem is usually ill posed. The third is the ever higher level of accuracy of the derived output sought after by end users that, rightly so, demand results (either direct or derived) they can use directly for management. Last, but not least, is the drive to incorporate different physical parameters originating from different sources into one inversion problem, in order to derive directly, e.g., geological or hydrogeological models that fit all data sets at once. In this paper we present examples obtained adding information from geophysics (i.e., seismic, surface and borehole geoelectric) and from geology (e.g., lithology), to the inversion of Airborne EM data from different systems (e.g., VTEM, AeroTEM, SkyTEM, Resolve). Case studies are from several areas in the world, with varied geological settings. In our formulation, the a-priori information is treated as nothing but an extra data set, carrying location, values, uncertainty, and expected lateral variability. The information it contains is spread to the location of the neighbouring AEM soundings, using the Spatially Constrained Inversion approach. Constraints and uncertainties are usually different depending on data types and geology. Case studies show the effect on the inversion results of the a-priori

  20. First-arrival traveltime sound speed inversion with a priori information

    PubMed Central

    Hooi, Fong Ming; Carson, Paul L.

    2014-01-01

    Purpose: A first-arrival travel-time sound speed algorithm presented byTarantola [Inverse Problem Theory and Methods for Model Parameter Estimation (SIAM, Philadelphia, PA, 2005)] is adapted to the medical ultrasonics setting. Through specification of a covariance matrix for the object model, the algorithm allows for natural inclusion of physical a priori information of the object. The algorithm's ability to accurately and robustly reconstruct a complex sound speed distribution is demonstrated on simulation and experimental data using a limited aperture. Methods: The algorithm is first demonstrated generally in simulation with a numerical breast phantom imaged in different geometries. As this work is motivated by the authors' limited aperture dual sided ultrasound breast imaging system, experimental data are acquired with a Verasonics system with dual, 128 element, linear L7-4 arrays. The transducers are automatically calibrated for usage in the eikonal forward model.A priori information such as knowledge of correlated regions within the object is obtained via segmentation of B-mode images generated from synthetic aperture imaging. Results: As one illustration of the algorithm's facility for inclusion ofa priori information, physically grounded regularization is demonstrated in simulation. The algorithm's practicality is then demonstrated through experimental realization in limited aperture cases. Reconstructions of sound speed distributions of various complexity are improved through inclusion of a priori information. The sound speed maps are generally reconstructed with accuracy within a few m/s. Conclusions: This paper demonstrates the ability to form sound speed images using two opposed commercial linear arrays to mimic ultrasound image acquisition in the compressed mammographic geometry. The ability to create reasonably good speed of sound images in the compressed mammographic geometry allows images to be readily coregistered to tomosynthesis image volumes for

  1. Evaluating A Priori Ozone Profile Information Used in TEMPO Tropospheric Ozone Retrievals

    NASA Astrophysics Data System (ADS)

    Johnson, M. S.; Sullivan, J. T.; Liu, X.; Newchurch, M.; Kuang, S.; McGee, T. J.; Langford, A. O.; Senff, C. J.; Leblanc, T.; Berkoff, T.; Gronoff, G.; Chen, G.; Strawbridge, K. B.

    2016-12-01

    Ozone (O3) is a greenhouse gas and toxic pollutant which plays a major role in air quality. Typically, monitoring of surface air quality and O3 mixing ratios is primarily conducted using in situ measurement networks. This is partially due to high-quality information related to air quality being limited from space-borne platforms due to coarse spatial resolution, limited temporal frequency, and minimal sensitivity to lower tropospheric and surface-level O3. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite is designed to address these limitations of current space-based platforms and to improve our ability to monitor North American air quality. TEMPO will provide hourly data of total column and vertical profiles of O3 with high spatial resolution to be used as a near-real-time air quality product. TEMPO O3 retrievals will apply the Smithsonian Astrophysical Observatory profile algorithm developed based on work from GOME, GOME-2, and OMI. This algorithm uses a priori O3 profile information from a climatological data-base developed from long-term ozone-sonde measurements (tropopause-based (TB) O3 climatology). It has been shown that satellite O3 retrievals are sensitive to a priori O3 profiles and covariance matrices. During this work we investigate the climatological data to be used in TEMPO algorithms (TB O3) and simulated data from the NASA GMAO Goddard Earth Observing System (GEOS-5) Forward Processing (FP) near-real-time (NRT) model products. These two data products will be evaluated with ground-based lidar data from the Tropospheric Ozone Lidar Network (TOLNet) at various locations of the US. This study evaluates the TB climatology, GEOS-5 climatology, and 3-hourly GEOS-5 data compared to lower tropospheric observations to demonstrate the accuracy of a priori information to potentially be used in TEMPO O3 algorithms. Here we present our initial analysis and the theoretical impact on TEMPO retrievals in the lower troposphere.

  2. A priori model independent inverse potential mapping: the impact of electrode positioning.

    PubMed

    van der Graaf, A W Maurits; Bhagirath, Pranav; de Hooge, Jacques; de Groot, Natasja M S; Götte, Marco J W

    2016-01-01

    In inverse potential mapping, local epicardial potentials are computed from recorded body surface potentials (BSP). When BSP are recorded with only a limited number of electrodes, in general biophysical a priori models are applied to facilitate the inverse computation. This study investigated the possibility of deriving epicardial potential information using only 62 torso electrodes in the absence of an a priori model. Computer simulations were used to determine the optimal in vivo positioning of 62 torso electrodes. Subsequently, three different electrode configurations, i.e., surrounding the thorax, concentrated precordial (30 mm inter-electrode distance) and super-concentrated precordial (20 mm inter-electrode distance) were used to record BSP from three healthy volunteers. Magnetic resonance imaging (MRI) was performed to register the electrode positions with respect to the anatomy of the patient. Epicardial potentials were inversely computed from the recorded BSP. In order to determine the reconstruction quality, the super-concentrated electrode configuration was applied in four patients with an implanted MRI-conditional pacemaker system. The distance between the position of the ventricular lead tip on MRI and the inversely reconstructed pacing site was determined. The epicardial potential distribution reconstructed using the super-concentrated electrode configuration demonstrated the highest correlation (R = 0.98; p < 0.01) with the original epicardial source model. A mean localization error of 5.3 mm was found in the pacemaker patients. This study demonstrated the feasibility of deriving detailed anterior epicardial potential information using only 62 torso electrodes without the use of an a priori model.

  3. Evaluating A Priori Ozone Profile Information Used in TEMPO Tropospheric Ozone Retrievals

    NASA Technical Reports Server (NTRS)

    Johnson, Matthew S.; Sullivan, John T.; Liu, Xiong; Newchurch, Mike; Kuang, Shi; McGee, Thomas J.; Langford, Andrew O'Neil; Senff, Christoph J.; Leblanc, Thierry; Berkoff, Timothy; Gronoff, Guillaume; Chen, Gao; Strawbridge, Kevin B.

    2016-01-01

    Ozone (O3) is a greenhouse gas and toxic pollutant which plays a major role in air quality. Typically, monitoring of surface air quality and O3 mixing ratios is primarily conducted using in situ measurement networks. This is partially due to high-quality information related to air quality being limited from space-borne platforms due to coarse spatial resolution, limited temporal frequency, and minimal sensitivity to lower tropospheric and surface-level O3. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite is designed to address these limitations of current space-based platforms and to improve our ability to monitor North American air quality. TEMPO will provide hourly data of total column and vertical profiles of O3 with high spatial resolution to be used as a near-real-time air quality product. TEMPO O3 retrievals will apply the Smithsonian Astrophysical Observatory profile algorithm developed based on work from GOME, GOME-2, and OMI. This algorithm uses a priori O3 profile information from a climatological data-base developed from long-term ozone-sonde measurements (tropopause-based (TB) O3 climatology). It has been shown that satellite O3 retrievals are sensitive to a priori O3 profiles and covariance matrices. During this work we investigate the climatological data to be used in TEMPO algorithms (TB O3) and simulated data from the NASA GMAO Goddard Earth Observing System (GEOS-5) Forward Processing (FP) near-real-time (NRT) model products. These two data products will be evaluated with ground-based lidar data from the Tropospheric Ozone Lidar Network (TOLNet) at various locations of the US. This study evaluates the TB climatology, GEOS-5 climatology, and 3-hourly GEOS-5 data compared to lower tropospheric observations to demonstrate the accuracy of a priori information to potentially be used in TEMPO O3 algorithms. Here we present our initial analysis and the theoretical impact on TEMPO retrievals in the lower troposphere.

  4. First-arrival traveltime sound speed inversion with a priori information.

    PubMed

    Hooi, Fong Ming; Carson, Paul L

    2014-08-01

    A first-arrival travel-time sound speed algorithm presented by Tarantola [Inverse Problem Theory and Methods for Model Parameter Estimation (SIAM, Philadelphia, PA, 2005)] is adapted to the medical ultrasonics setting. Through specification of a covariance matrix for the object model, the algorithm allows for natural inclusion of physical a priori information of the object. The algorithm's ability to accurately and robustly reconstruct a complex sound speed distribution is demonstrated on simulation and experimental data using a limited aperture. The algorithm is first demonstrated generally in simulation with a numerical breast phantom imaged in different geometries. As this work is motivated by the authors' limited aperture dual sided ultrasound breast imaging system, experimental data are acquired with a Verasonics system with dual, 128 element, linear L7-4 arrays. The transducers are automatically calibrated for usage in the eikonal forward model.A priori information such as knowledge of correlated regions within the object is obtained via segmentation of B-mode images generated from synthetic aperture imaging. As one illustration of the algorithm's facility for inclusion ofa priori information, physically grounded regularization is demonstrated in simulation. The algorithm's practicality is then demonstrated through experimental realization in limited aperture cases. Reconstructions of sound speed distributions of various complexity are improved through inclusion of a priori information. The sound speed maps are generally reconstructed with accuracy within a few m/s. This paper demonstrates the ability to form sound speed images using two opposed commercial linear arrays to mimic ultrasound image acquisition in the compressed mammographic geometry. The ability to create reasonably good speed of sound images in the compressed mammographic geometry allows images to be readily coregistered to tomosynthesis image volumes for breast cancer detection and

  5. 3SMAC: an a priori tomographic model of the upper mantle based on geophysical modeling

    NASA Astrophysics Data System (ADS)

    Nataf, Henri-Claude; Ricard, Yanick

    1996-05-01

    We present an a priori three-dimensional 'tomographic' model of the upper mantle. We construct this model (called 3SMAC — three-dimensional seismological model a priori constrained) in four steps: we compile information on the thickness of 'chemical' layers in the Earth (water, sediments, upper and lower crust, etc); we get a 3D temperature distribution from thermal plate models applied to the oceans and continents; we deduce the mineralogy in the mantle from pressure and temperature and we finally get a three-dimensional model of density, seismic velocities, and attenuation by introducing laboratory measurements of these quantities as a function of pressure and temperature. The model is thus consistent with various geophysical data, such as ocean bathymetry, and surface heat flux. We use this model to compute synthetic travel-times of body waves, and we compare them with observations. A similar exercise is performed for surface waves and normal modes in a companion paper (Ricard et al., 1996, J. Geophys. Res., in press). We find that our model predicts the bulk of the observed travel-time variations. Both the amplitude and general pattern are well recovered. The discrepancies suggest that tomography can provide useful regional information on the thermal state of the continents. In the oceans, the flattening of the sea-floor beond 70 Ma seems difficult to reconcile with the seismic observations. Overall, our 3SMAC model is both a realistic model, which can be used to test various tomographic methods, and a model of the minimum heterogeneities to be expected from geodynamical modeling. Therefore, it should be a useful a priori model to be used in tomographic inversions, in order to retrieve reliable images of heterogeneities in the transition zone, which should, in turn, greatly improve our understanding of geodynamical processes in the deep Earth. 3SMAC and accompanying software can be retrieved by anonymous ftp at geoscope.ipgp.jussieu.fr.

  6. An a priori solar radiation pressure model for the QZSS Michibiki satellite

    NASA Astrophysics Data System (ADS)

    Zhao, Qile; Chen, Guo; Guo, Jing; Liu, Jingnan; Liu, Xianglin

    2017-07-01

    It has been noted that the satellite laser ranging (SLR) residuals of the Quasi-Zenith Satellite System (QZSS) Michibiki satellite orbits show very marked dependence on the elevation angle of the Sun above the orbital plane (i.e., the β angle). It is well recognized that the systematic error is caused by mismodeling of the solar radiation pressure (SRP). Although the error can be reduced by the updated ECOM SRP model, the orbit error is still very large when the satellite switches to orbit-normal (ON) orientation. In this study, an a priori SRP model was established for the QZSS Michibiki satellite to enhance the ECOM model. This model is expressed in ECOM's D, Y, and B axes (DYB) using seven parameters for the yaw-steering (YS) mode, and additional three parameters are used to compensate the remaining modeling deficiencies, particularly the perturbations in the Y axis, based on a redefined DYB for the ON mode. With the proposed a priori model, QZSS Michibiki's precise orbits over 21 months were determined. SLR validation indicated that the systematic β -angle-dependent error was reduced when the satellite was in the YS mode, and better than an 8-cm root mean square (RMS) was achieved. More importantly, the orbit quality was also improved significantly when the satellite was in the ON mode. Relative to ECOM and adjustable box-wing model, the proposed SRP model showed the best performance in the ON mode, and the RMS of the SLR residuals was better than 15 cm, which was a two times improvement over the ECOM without a priori model used, but was still two times worse than the YS mode.

  7. Note: Reconstruction of fluid flows in porous media using geometric a priori information

    NASA Astrophysics Data System (ADS)

    Maisl, Michael; Scholl, Hagen; Schorr, Christian; Seemann, Ralf

    2016-12-01

    X-ray tomography typically suffers from insufficient temporal resolution when imaging dynamic processes. Using the example of multiphase flow in solid porous media, we adapt an iterative algorithm to compute 3d tomograms from 2d projections, which allows for a significant reduction of scan time while maintaining a high level of reconstruction quality. To this end, a priori knowledge about the porous medium is incorporated into the reconstruction algorithm. This algorithm is universal when monitoring dynamic changes in any static matrix and allows for an at least five times decreased imaging time with respect to standard reconstruction algorithms.

  8. Note: Reconstruction of fluid flows in porous media using geometric a priori information.

    PubMed

    Maisl, Michael; Scholl, Hagen; Schorr, Christian; Seemann, Ralf

    2016-12-01

    X-ray tomography typically suffers from insufficient temporal resolution when imaging dynamic processes. Using the example of multiphase flow in solid porous media, we adapt an iterative algorithm to compute 3d tomograms from 2d projections, which allows for a significant reduction of scan time while maintaining a high level of reconstruction quality. To this end, a priori knowledge about the porous medium is incorporated into the reconstruction algorithm. This algorithm is universal when monitoring dynamic changes in any static matrix and allows for an at least five times decreased imaging time with respect to standard reconstruction algorithms.

  9. Proportionality of Components, Liouville Theorems and a Priori Estimates for Noncooperative Elliptic Systems

    NASA Astrophysics Data System (ADS)

    Montaru, Alexandre; Sirakov, Boyan; Souplet, Philippe

    2014-07-01

    We study qualitative properties of positive solutions of noncooperative, possibly nonvariational, elliptic systems. We obtain new classification and Liouville type theorems in the whole Euclidean space, as well as in half-spaces, and deduce a priori estimates and the existence of positive solutions for related Dirichlet problems. We significantly improve the known results for a large class of systems involving a balance between repulsive and attractive terms. This class contains systems arising in biological models of Lotka-Volterra type, in physical models of Bose-Einstein condensates and in models of chemical reactions.

  10. Visual identification and similarity measures used for on-line motion planning of autonomous robots in unknown environments

    NASA Astrophysics Data System (ADS)

    Martínez, Fredy; Martínez, Fernando; Jacinto, Edwar

    2017-02-01

    In this paper we propose an on-line motion planning strategy for autonomous robots in dynamic and locally observable environments. In this approach, we first visually identify geometric shapes in the environment by filtering images. Then, an ART-2 network is used to establish the similarity between patterns. The proposed algorithm allows that a robot establish its relative location in the environment, and define its navigation path based on images of the environment and its similarity to reference images. This is an efficient and minimalist method that uses the similarity of landmark view patterns to navigate to the desired destination. Laboratory tests on real prototypes demonstrate the performance of the algorithm.

  11. Algorithms for magnetic tomography—on the role of a priori knowledge and constraints

    NASA Astrophysics Data System (ADS)

    Hauer, Karl-Heinz; Potthast, Roland; Wannert, Martin

    2008-08-01

    Magnetic tomography investigates the reconstruction of currents from their magnetic fields. Here, we will study a number of projection methods in combination with the Tikhonov regularization for stabilization for the solution of the Biot-Savart integral equation Wj = H with the Biot-Savart integral operator W:(L2(Ω))3 → (L2(∂G))3 where \\overline{\\Omega} \\subset G . In particular, we study the role of a priori knowledge when incorporated into the choice of the projection spaces X_n \\subset (L^2(\\Omega))^3, n\\in {\\bb N} , for example the conditions div j = 0 or the use of the full boundary value problem div σgrad phivE = 0 in Ω, ν sdot σgrad phivE = g on ∂Ω with some known function g, where j = σgrad phivE and σ is an anisotropic matrix-valued conductivity. We will discuss and compare these schemes investigating the ill-posedness of each algorithm in terms of the behaviour of the singular values of the corresponding operators both when a priori knowledge is incorporated and when the geometrical setting is modified. Finally, we will numerically evaluate the stability constants in the practical setup of magnetic tomography for fuel cells and, thus, calculate usable error bounds for this important application area.

  12. The a priori SDR Estimation Techniques with Reduced Speech Distortion for Acoustic Echo and Noise Suppression

    NASA Astrophysics Data System (ADS)

    Thoonsaengngam, Rattapol; Tangsangiumvisai, Nisachon

    This paper proposes an enhanced method for estimating the a priori Signal-to-Disturbance Ratio (SDR) to be employed in the Acoustic Echo and Noise Suppression (AENS) system for full-duplex hands-free communications. The proposed a priori SDR estimation technique is modified based upon the Two-Step Noise Reduction (TSNR) algorithm to suppress the background noise while preserving speech spectral components. In addition, a practical approach to determine accurately the Echo Spectrum Variance (ESV) is presented based upon the linear relationship assumption between the power spectrum of far-end speech and acoustic echo signals. The ESV estimation technique is then employed to alleviate the acoustic echo problem. The performance of the AENS system that employs these two proposed estimation techniques is evaluated through the Echo Attenuation (EA), Noise Attenuation (NA), and two speech distortion measures. Simulation results based upon real speech signals guarantee that our improved AENS system is able to mitigate efficiently the problem of acoustic echo and background noise, while preserving the speech quality and speech intelligibility.

  13. Normalization of T2W-MRI prostate images using Rician a priori

    NASA Astrophysics Data System (ADS)

    Lemaître, Guillaume; Rastgoo, Mojdeh; Massich, Joan; Vilanova, Joan C.; Walker, Paul M.; Freixenet, Jordi; Meyer-Baese, Anke; Mériaudeau, Fabrice; Martí, Robert

    2016-03-01

    Prostate cancer is reported to be the second most frequently diagnosed cancer of men in the world. In practise, diagnosis can be affected by multiple factors which reduces the chance to detect the potential lesions. In the last decades, new imaging techniques mainly based on MRI are developed in conjunction with Computer-Aided Diagnosis (CAD) systems to help radiologists for such diagnosis. CAD systems are usually designed as a sequential process consisting of four stages: pre-processing, segmentation, registration and classification. As a pre-processing, image normalization is a critical and important step of the chain in order to design a robust classifier and overcome the inter-patients intensity variations. However, little attention has been dedicated to the normalization of T2W-Magnetic Resonance Imaging (MRI) prostate images. In this paper, we propose two methods to normalize T2W-MRI prostate images: (i) based on a Rician a priori and (ii) based on a Square-Root Slope Function (SRSF) representation which does not make any assumption regarding the Probability Density Function (PDF) of the data. A comparison with the state-of-the-art methods is also provided. The normalization of the data is assessed by comparing the alignment of the patient PDFs in both qualitative and quantitative manners. In both evaluation, the normalization using Rician a priori outperforms the other state-of-the-art methods.

  14. Determining the depth of certain gravity sources without a priori specification of their structural index

    NASA Astrophysics Data System (ADS)

    Zhou, Shuai; Huang, Danian

    2015-11-01

    We have developed a new method for the interpretation of gravity tensor data based on the generalized Tilt-depth method. Cooper (2011, 2012) extended the magnetic Tilt-depth method to gravity data. We take the gradient-ratio method of Cooper (2011, 2012) and modify it so that the source type does not need to be specified a priori. We develop the new method by generalizing the Tilt-depth method for depth estimation for different types of source bodies. The new technique uses only the three vertical tensor components of the full gravity tensor data observed or calculated at different height plane to estimate the depth of the buried bodies without a priori specification of their structural index. For severely noise-corrupted data, our method utilizes different upward continuation height data, which can effectively reduce the influence of noise. Theoretical simulations of the gravity source model with and without noise illustrate the ability of the method to provide source depth information. Additionally, the simulations demonstrate that the new method is simple, computationally fast and accurate. Finally, we apply the method using the gravity data acquired over the Humble Salt Dome in the USA as an example. The results show a good correspondence to the previous drilling and seismic interpretation results.

  15. Template based rotation: A method for functional connectivity analysis with a priori templates☆

    PubMed Central

    Schultz, Aaron P.; Chhatwal, Jasmeer P.; Huijbers, Willem; Hedden, Trey; van Dijk, Koene R.A.; McLaren, Donald G.; Ward, Andrew M.; Wigman, Sarah; Sperling, Reisa A.

    2014-01-01

    Functional connectivity magnetic resonance imaging (fcMRI) is a powerful tool for understanding the network level organization of the brain in research settings and is increasingly being used to study large-scale neuronal network degeneration in clinical trial settings. Presently, a variety of techniques, including seed-based correlation analysis and group independent components analysis (with either dual regression or back projection) are commonly employed to compute functional connectivity metrics. In the present report, we introduce template based rotation,1 a novel analytic approach optimized for use with a priori network parcellations, which may be particularly useful in clinical trial settings. Template based rotation was designed to leverage the stable spatial patterns of intrinsic connectivity derived from out-of-sample datasets by mapping data from novel sessions onto the previously defined a priori templates. We first demonstrate the feasibility of using previously defined a priori templates in connectivity analyses, and then compare the performance of template based rotation to seed based and dual regression methods by applying these analytic approaches to an fMRI dataset of normal young and elderly subjects. We observed that template based rotation and dual regression are approximately equivalent in detecting fcMRI differences between young and old subjects, demonstrating similar effect sizes for group differences and similar reliability metrics across 12 cortical networks. Both template based rotation and dual-regression demonstrated larger effect sizes and comparable reliabilities as compared to seed based correlation analysis, though all three methods yielded similar patterns of network differences. When performing inter-network and sub-network connectivity analyses, we observed that template based rotation offered greater flexibility, larger group differences, and more stable connectivity estimates as compared to dual regression and seed based

  16. Template based rotation: a method for functional connectivity analysis with a priori templates.

    PubMed

    Schultz, Aaron P; Chhatwal, Jasmeer P; Huijbers, Willem; Hedden, Trey; van Dijk, Koene R A; McLaren, Donald G; Ward, Andrew M; Wigman, Sarah; Sperling, Reisa A

    2014-11-15

    Functional connectivity magnetic resonance imaging (fcMRI) is a powerful tool for understanding the network level organization of the brain in research settings and is increasingly being used to study large-scale neuronal network degeneration in clinical trial settings. Presently, a variety of techniques, including seed-based correlation analysis and group independent components analysis (with either dual regression or back projection) are commonly employed to compute functional connectivity metrics. In the present report, we introduce template based rotation,(1) a novel analytic approach optimized for use with a priori network parcellations, which may be particularly useful in clinical trial settings. Template based rotation was designed to leverage the stable spatial patterns of intrinsic connectivity derived from out-of-sample datasets by mapping data from novel sessions onto the previously defined a priori templates. We first demonstrate the feasibility of using previously defined a priori templates in connectivity analyses, and then compare the performance of template based rotation to seed based and dual regression methods by applying these analytic approaches to an fMRI dataset of normal young and elderly subjects. We observed that template based rotation and dual regression are approximately equivalent in detecting fcMRI differences between young and old subjects, demonstrating similar effect sizes for group differences and similar reliability metrics across 12 cortical networks. Both template based rotation and dual-regression demonstrated larger effect sizes and comparable reliabilities as compared to seed based correlation analysis, though all three methods yielded similar patterns of network differences. When performing inter-network and sub-network connectivity analyses, we observed that template based rotation offered greater flexibility, larger group differences, and more stable connectivity estimates as compared to dual regression and seed based

  17. A priori analysis: an application to the estimate of the uncertainty in course grades

    NASA Astrophysics Data System (ADS)

    Lippi, G. L.

    2014-07-01

    A priori analysis (APA) is discussed as a tool to assess the reliability of grades in standard curricular courses. This unusual, but striking, application is presented when teaching the section on the data treatment of a laboratory course to illustrate the characteristics of the APA and its potential for widespread use, beyond the traditional physics curriculum. The conditions necessary for this kind of analysis are discussed, the general framework is set out and a specific example is given to illustrate its various aspects. Students are often struck by this unusual application and are more apt to remember the APA. Instructors may also benefit from some of the gathered information, as discussed in the paper.

  18. GNSS Precise Kinematic Positioning for Multiple Kinematic Stations Based on A Priori Distance Constraints.

    PubMed

    He, Kaifei; Xu, Tianhe; Förste, Christoph; Petrovic, Svetozar; Barthelmes, Franz; Jiang, Nan; Flechtner, Frank

    2016-04-01

    When applying the Global Navigation Satellite System (GNSS) for precise kinematic positioning in airborne and shipborne gravimetry, multiple GNSS receiving equipment is often fixed mounted on the kinematic platform carrying the gravimetry instrumentation. Thus, the distances among these GNSS antennas are known and invariant. This information can be used to improve the accuracy and reliability of the state estimates. For this purpose, the known distances between the antennas are applied as a priori constraints within the state parameters adjustment. These constraints are introduced in such a way that their accuracy is taken into account. To test this approach, GNSS data of a Baltic Sea shipborne gravimetric campaign have been used. The results of our study show that an application of distance constraints improves the accuracy of the GNSS kinematic positioning, for example, by about 4 mm for the radial component.

  19. GNSS Precise Kinematic Positioning for Multiple Kinematic Stations Based on A Priori Distance Constraints

    PubMed Central

    He, Kaifei; Xu, Tianhe; Förste, Christoph; Petrovic, Svetozar; Barthelmes, Franz; Jiang, Nan; Flechtner, Frank

    2016-01-01

    When applying the Global Navigation Satellite System (GNSS) for precise kinematic positioning in airborne and shipborne gravimetry, multiple GNSS receiving equipment is often fixed mounted on the kinematic platform carrying the gravimetry instrumentation. Thus, the distances among these GNSS antennas are known and invariant. This information can be used to improve the accuracy and reliability of the state estimates. For this purpose, the known distances between the antennas are applied as a priori constraints within the state parameters adjustment. These constraints are introduced in such a way that their accuracy is taken into account. To test this approach, GNSS data of a Baltic Sea shipborne gravimetric campaign have been used. The results of our study show that an application of distance constraints improves the accuracy of the GNSS kinematic positioning, for example, by about 4 mm for the radial component. PMID:27043580

  20. A priori mesh quality metrics for three-dimensional hybrid grids

    SciTech Connect

    Kallinderis, Y. Fotia, S.

    2015-01-01

    Use of general hybrid grids to attain complex-geometry field simulations poses a challenge on estimation of their quality. Apart from the typical problems of non-uniformity and non-orthogonality, the change in element topology is an extra issue to address. The present work derives and evaluates an a priori mesh quality indicator for structured, unstructured, as well as hybrid grids consisting of hexahedra, prisms, tetrahedra, and pyramids. Emphasis is placed on deriving a direct relation between the quality measure and mesh distortion. The work is based on use of the Finite Volume discretization for evaluation of first order spatial derivatives. The analytic form of the truncation error is derived and applied to elementary types of mesh distortion including typical hybrid grid interfaces. The corresponding analytic expressions provide relations between the truncation error and the degree of stretching, skewness, shearing, torsion, expansion, as well as the type of grid interface.

  1. A priori analysis of a LES subfilter model for soot-turbulence-chemistry interactions

    NASA Astrophysics Data System (ADS)

    Lew, Jeffry K.; Mueller, Michael E.

    2016-11-01

    In a turbulent flame, soot interacts with turbulence and combustion chemistry at the smallest scales. An existing LES subfilter model proposes that soot-turbulence interactions are independent of chemistry due to the time scale separation between slow soot formation and rapid heat-releasing reactions. However, interactions between soot, turbulence, and chemistry occur even after the nucleation of soot from polycyclic aromatic hydrocarbon (PAH) dimers. In fact, the interplay of soot and gas-phase chemistry may be intensified during oxidation and surface growth. To capture these effects, a dependence on the local mixture fraction has been introduced into the subfilter model. This modified model is evaluated a priori using a direct numerical simulation (DNS) database of soot evolution in a turbulent non-premixed n-heptane/air jet flame.

  2. A method to unmix multiple fluorophores in microscopy images with minimal a priori information.

    PubMed

    Schlachter, S; Schwedler, S; Esposito, A; Kaminski Schierle, G S; Moggridge, G D; Kaminski, C F

    2009-12-07

    The ability to quantify the fluorescence signals from multiply labeled biological samples is highly desirable in the life sciences but often difficult, because of spectral overlap between fluorescent species and the presence of autofluorescence. Several so called unmixing algorithms have been developed to address this problem. Here, we present a novel algorithm that combines measurements of lifetime and spectrum to achieve unmixing without a priori information on the spectral properties of the fluorophore labels. The only assumption made is that the lifetimes of the fluorophores differ. Our method combines global analysis for a measurement of lifetime distributions with singular value decomposition to recover individual fluorescence spectra. We demonstrate the technique on simulated datasets and subsequently by an experiment on a biological sample. The method is computationally efficient and straightforward to implement. Applications range from histopathology of complex and multiply labelled samples to functional imaging in live cells.

  3. A priori postulated and real power in cluster randomized trials: mind the gap.

    PubMed

    Guittet, Lydia; Giraudeau, Bruno; Ravaud, Philippe

    2005-08-18

    Cluster randomization design is increasingly used for the evaluation of health-care, screening or educational interventions. The intraclass correlation coefficient (ICC) defines the clustering effect and be specified during planning. The aim of this work is to study the influence of the ICC on power in cluster randomized trials. Power contour graphs were drawn to illustrate the loss in power induced by an underestimation of the ICC when planning trials. We also derived the maximum achievable power given a specified ICC. The magnitude of the ICC can have a major impact on power, and with low numbers of clusters, 80% power may not be achievable. Underestimating the ICC during planning cluster randomized trials can lead to a seriously underpowered trial. Publication of a priori postulated and a posteriori estimated ICCs is necessary for a more objective reading: negative trial results may be the consequence of a loss of power due to a mis-specification of the ICC.

  4. A Priori Estimates for Free Boundary Problem of Incompressible Inviscid Magnetohydrodynamic Flows

    NASA Astrophysics Data System (ADS)

    Hao, Chengchun; Luo, Tao

    2014-06-01

    In the present paper, we prove the a priori estimates of Sobolev norms for a free boundary problem of the incompressible inviscid magnetohydrodynamics equations in all physical spatial dimensions n = 2 and 3 by adopting a geometrical point of view used in Christodoulou and Lindblad (Commun Pure Appl Math 53:1536-1602, 2000), and estimating quantities such as the second fundamental form and the velocity of the free surface. We identify the well-posedness condition that the outer normal derivative of the total pressure including the fluid and magnetic pressures is negative on the free boundary, which is similar to the physical condition (Taylor sign condition) for the incompressible Euler equations of fluids.

  5. A Priori Estimates for Fractional Nonlinear Degenerate Diffusion Equations on Bounded Domains

    NASA Astrophysics Data System (ADS)

    Bonforte, Matteo; Vázquez, Juan Luis

    2015-10-01

    We investigate quantitative properties of the nonnegative solutions to the nonlinear fractional diffusion equation, , posed in a bounded domain, , with m > 1 for t > 0. As we use one of the most common definitions of the fractional Laplacian , 0 < s < 1, in a bounded domain with zero Dirichlet boundary conditions. We consider a general class of very weak solutions of the equation, and obtain a priori estimates in the form of smoothing effects, absolute upper bounds, lower bounds, and Harnack inequalities. We also investigate the boundary behaviour and we obtain sharp estimates from above and below. In addition, we obtain similar estimates for fractional semilinear elliptic equations. Either the standard Laplacian case s = 1 or the linear case m = 1 are recovered as limits. The method is quite general, suitable to be applied to a number of similar problems.

  6. Predicting thermal history a-priori for magnetic nanoparticle hyperthermia of internal carcinoma

    NASA Astrophysics Data System (ADS)

    Dhar, Purbarun; Sirisha Maganti, Lakshmi

    2017-08-01

    This article proposes a simplistic and realistic method where a direct analytical expression can be derived for the temperature field within a tumour during magnetic nanoparticle hyperthermia. The approximated analytical expression for thermal history within the tumour is derived based on the lumped capacitance approach and considers all therapy protocols and parameters. The present method is simplistic and provides an easy framework for estimating hyperthermia protocol parameters promptly. The model has been validated with respect to several experimental reports on animal models such as mice/rabbit/hamster and human clinical trials. It has been observed that the model is able to accurately estimate the thermal history within the carcinoma during the hyperthermia therapy. The present approach may find implications in a-priori estimation of the thermal history in internal tumours for optimizing magnetic hyperthermia treatment protocols with respect to the ablation time, tumour size, magnetic drug concentration, field strength, field frequency, nanoparticle material and size, tumour location, and so on.

  7. Rapid multi-wavelength optical assessment of circulating blood volume without a priori data

    NASA Astrophysics Data System (ADS)

    Loginova, Ekaterina V.; Zhidkova, Tatyana V.; Proskurnin, Mikhail A.; Zharov, Vladimir P.

    2016-03-01

    The measurement of circulating blood volume (CBV) is crucial in various medical conditions including surgery, iatrogenic problems, rapid fluid administration, transfusion of red blood cells, or trauma with extensive blood loss including battlefield injuries and other emergencies. Currently, available commercial techniques are invasive and time-consuming for trauma situations. Recently, we have proposed high-speed multi-wavelength photoacoustic/photothermal (PA/PT) flow cytometry for in vivo CBV assessment with multiple dyes as PA contrast agents (labels). As the first step, we have characterized the capability of this technique to monitor the clearance of three dyes (indocyanine green, methylene blue, and trypan blue) in an animal model. However, there are strong demands on improvements in PA/PT flow cytometry. As additional verification of our proof-of-concept of this technique, we performed optical photometric CBV measurements in vitro. Three label dyes—methylene blue, crystal violet and, partially, brilliant green—were selected for simultaneous photometric determination of the components of their two-dye mixtures in the circulating blood in vitro without any extra data (like hemoglobin absorption) known a priori. The tests of single dyes and their mixtures in a flow system simulating a blood transfusion system showed a negligible difference between the sensitivities of the determination of these dyes under batch and flow conditions. For individual dyes, the limits of detection of 3×10-6 M‒3×10-6 M in blood were achieved, which provided their continuous determination at a level of 10-5 M for the CBV assessment without a priori data on the matrix. The CBV assessment with errors no higher than 4% were obtained, and the possibility to apply the developed procedure for optical photometric (flow cytometry) with laser sources was shown.

  8. Methods for improving limited field-of-view radiotherapy reconstructions using imperfect a priori images.

    PubMed

    Ruchala, Kenneth J; Olivera, Gustavo H; Kapatoes, Jeffrey M; Reckwerdt, Paul J; Mackie, Thomas R

    2002-11-01

    There are many benefits to having an online CT imaging system for radiotherapy, as it helps identify changes in the patient's position and anatomy between the time of planning and treatment. However, many current online CT systems suffer from a limited field-of-view (LFOV) in that collected data do not encompass the patient's complete cross section. Reconstruction of these data sets can quantitatively distort the image values and introduce artifacts. This work explores the use of planning CT data as a priori information for improving these reconstructions. Methods are presented to incorporate this data by aligning the LFOV with the planning images and then merging the data sets in sinogram space. One alignment option is explicit fusion, producing fusion-aligned reprojection (FAR) images. For cases where explicit fusion is not viable, FAR can be implemented using the implicit fusion of normal setup error, referred to as normal-error-aligned reprojection (NEAR). These methods are evaluated for multiday patient images showing both internal and skin-surface anatomical variation. The iterative use of NEAR and FAR is also investigated, as are applications of NEAR and FAR to dose calculations and the compensation of LFOV online MVCT images with kVCT planning images. Results indicate that NEAR and FAR can utilize planning CT data as imperfect a priori information to reduce artifacts and quantitatively improve images. These benefits can also increase the accuracy of dose calculations and be used for augmenting CT images (e.g., MVCT) acquired at different energies than the planning CT.

  9. Self-Organized Multi-Camera Network for a Fast and Easy Deployment of Ubiquitous Robots in Unknown Environments

    PubMed Central

    Canedo-Rodriguez, Adrián; Iglesias, Roberto; Regueiro, Carlos V.; Alvarez-Santos, Victor; Pardo, Xose Manuel

    2013-01-01

    To bring cutting edge robotics from research centres to social environments, the robotics community must start providing affordable solutions: the costs must be reduced and the quality and usefulness of the robot services must be enhanced. Unfortunately, nowadays the deployment of robots and the adaptation of their services to new environments are tasks that usually require several days of expert work. With this in view, we present a multi-agent system made up of intelligent cameras and autonomous robots, which is easy and fast to deploy in different environments. The cameras will enhance the robot perceptions and allow them to react to situations that require their services. Additionally, the cameras will support the movement of the robots. This will enable our robots to navigate even when there are not maps available. The deployment of our system does not require expertise and can be done in a short period of time, since neither software nor hardware tuning is needed. Every system task is automatic, distributed and based on self-organization processes. Our system is scalable, robust, and flexible to the environment. We carried out several real world experiments, which show the good performance of our proposal. PMID:23271604

  10. Self-organized multi-camera network for a fast and easy deployment of ubiquitous robots in unknown environments.

    PubMed

    Canedo-Rodriguez, Adrián; Iglesias, Roberto; Regueiro, Carlos V; Alvarez-Santos, Victor; Pardo, Xose Manuel

    2012-12-27

    To bring cutting edge robotics from research centres to social environments, the robotics community must start providing affordable solutions: the costs must be reduced and the quality and usefulness of the robot services must be enhanced. Unfortunately, nowadays the deployment of robots and the adaptation of their services to new environments are tasks that usually require several days of expert work. With this in view, we present a multi-agent system made up of intelligent cameras and autonomous robots, which is easy and fast to deploy in different environments. The cameras will enhance the robot perceptions and allow them to react to situations that require their services. Additionally, the cameras will support the movement of the robots. This will enable our robots to navigate even when there are not maps available. The deployment of our system does not require expertise and can be done in a short period of time, since neither software nor hardware tuning is needed. Every system task is automatic, distributed and based on self-organization processes. Our system is scalable, robust, and flexible to the environment. We carried out several real world experiments, which show the good performance of our proposal.

  11. A-Priori Rupture Models for Northern California Type-A Faults

    USGS Publications Warehouse

    Wills, Chris J.; Weldon, Ray J.; Field, Edward H.

    2008-01-01

    This appendix describes how a-priori rupture models were developed for the northern California Type-A faults. As described in the main body of this report, and in Appendix G, ?a-priori? models represent an initial estimate of the rate of single and multi-segment surface ruptures on each fault. Whether or not a given model is moment balanced (i.e., satisfies section slip-rate data) depends on assumptions made regarding the average slip on each segment in each rupture (which in turn depends on the chosen magnitude-area relationship). Therefore, for a given set of assumptions, or branch on the logic tree, the methodology of the present Working Group (WGCEP-2007) is to find a final model that is as close as possible to the a-priori model, in the least squares sense, but that also satisfies slip rate and perhaps other data. This is analogous the WGCEP- 2002 approach of effectively voting on the relative rate of each possible rupture, and then finding the closest moment-balance model (under a more limiting set of assumptions than adopted by the present WGCEP, as described in detail in Appendix G). The 2002 Working Group Report (WCCEP, 2003, referred to here as WGCEP-2002), created segmented earthquake rupture forecast models for all faults in the region, including some that had been designated as Type B faults in the NSHMP, 1996, and one that had not previously been considered. The 2002 National Seismic Hazard Maps used the values from WGCEP-2002 for all the faults in the region, essentially treating all the listed faults as Type A faults. As discussed in Appendix A, the current WGCEP found that there are a number of faults with little or no data on slip-per-event, or dates of previous earthquakes. As a result, the WGCEP recommends that faults with minimal available earthquake recurrence data: the Greenville, Mount Diablo, San Gregorio, Monte Vista-Shannon and Concord-Green Valley be modeled as Type B faults to be consistent with similarly poorly-known faults statewide

  12. Testing the plausibility of several a priori assumed error distributions for discharge measurements

    NASA Astrophysics Data System (ADS)

    Van Eerdenbrugh, Katrien; Verhoest, Niko E. C.

    2017-04-01

    Hydrologic measurements are used for a variety of research topics and operational projects. Regardless of the application, it is important to account for measurement uncertainty. In many projects, no local information is available about this uncertainty. Therefore, error distributions and accompanying parameters or uncertainty boundaries are often taken from literature without any knowledge about their applicability in the new context. In this research, an approach is proposed that uses relative differences between simultaneous discharge measurements to test the plausibility of several a priori assumed error distributions. For this test, simultaneous discharge measurements (measured with one type of device) from nine different Belgian rivers were available. This implies the assumption that their error distribution does not depend upon river, measurement location and measurement team. Moreover, it is assumed that the errors of two simultaneous measurements are not mutually dependent. This data set does not allow for a direct assessment of measurement errors. However, independently of the value of the real discharge, the relative difference between two simultaneous measurements can be expressed by their relative measurement errors. If a distribution is assumed for these errors, it is thus possible to test equality between the distributions of both the relative differences of the simultaneously measured discharge pairs and a created set of relative differences based on two equally sized samples of measurement errors from the assumed distribution. If the assumed error distribution is correct, these two data sets will have the same distribution. In this research, equality is tested with a two-sample nonparametric Kolmogorov-Smirnov test. The resulting p-value and the corresponding value of the Kolmogorov-Smirnov statistic (KS statistic) are used for this evaluation. The occurrence of a high p-value (and corresponding small value of the KS statistic) provides no

  13. A priori mesh quality metric error analysis applied to a high-order finite element method

    NASA Astrophysics Data System (ADS)

    Lowrie, W.; Lukin, V. S.; Shumlak, U.

    2011-06-01

    Characterization of computational mesh's quality prior to performing a numerical simulation is an important step in insuring that the result is valid. A highly distorted mesh can result in significant errors. It is therefore desirable to predict solution accuracy on a given mesh. The HiFi/SEL high-order finite element code is used to study the effects of various mesh distortions on solution quality of known analytic problems for spatial discretizations with different order of finite elements. The measured global error norms are compared to several mesh quality metrics by independently varying both the degree of the distortions and the order of the finite elements. It is found that the spatial spectral convergence rates are preserved for all considered distortion types, while the total error increases with the degree of distortion. For each distortion type, correlations between the measured solution error and the different mesh metrics are quantified, identifying the most appropriate overall mesh metric. The results show promise for future a priori computational mesh quality determination and improvement.

  14. Control-relevant models for glucose control using a priori patient characteristics.

    PubMed

    van Heusden, Klaske; Dassau, Eyal; Zisser, Howard C; Seborg, Dale E; Doyle, Francis J

    2012-07-01

    One of the difficulties in the development of a reliable artificial pancreas for people with type 1 diabetes mellitus (T1DM) is the lack of accurate models of an individual's response to insulin. Most control algorithms proposed to control the glucose level in subjects with T1DM are model-based. Avoiding postprandial hypoglycemia ( 60 mg/dl) while minimizing prandial hyperglycemia ( > 180 mg/dl) has shown to be difficult in a closed-loop setting due to the patient-model mismatch. In this paper, control-relevant models are developed for T1DM, as opposed to models that minimize a prediction error. The parameters of these models are chosen conservatively to minimize the likelihood of hypoglycemia events. To limit the conservatism due to large intersubject variability, the models are personalized using a priori patient characteristics. The models are implemented in a zone model predictive control algorithm. The robustness of these controllers is evaluated in silico, where hypoglycemia is completely avoided even after large meal disturbances. The proposed control approach is simple and the controller can be set up by a physician without the need for control expertise.

  15. A Second Order Expansion of the Separatrix Map for Trigonometric Perturbations of a Priori Unstable Systems

    NASA Astrophysics Data System (ADS)

    Guardia, M.; Kaloshin, V.; Zhang, J.

    2016-11-01

    In this paper we study a so-called separatrix map introduced by Zaslavskii-Filonenko (Sov Phys JETP 27:851-857, 1968) and studied by Treschev (Physica D 116(1-2):21-43, 1998; J Nonlinear Sci 12(1):27-58, 2002), Piftankin (Nonlinearity (19):2617-2644, 2006) Piftankin and Treshchëv (Uspekhi Mat Nauk 62(2(374)):3-108, 2007). We derive a second order expansion of this map for trigonometric perturbations. In Castejon et al. (Random iteration of maps of a cylinder and diffusive behavior. Preprint available at arXiv:1501.03319, 2015), Guardia and Kaloshin (Stochastic diffusive behavior through big gaps in a priori unstable systems (in preparation), 2015), and Kaloshin et al. (Normally Hyperbolic Invariant Laminations and diffusive behavior for the generalized Arnold example away from resonances. Preprint available at http://www.terpconnect.umd.edu/vkaloshi/, 2015), applying the results of the present paper, we describe a class of nearly integrable deterministic systems with stochastic diffusive behavior.

  16. A Priori Analysis of Flamelet-Based Modeling for a Dual-Mode Scramjet Combustor

    NASA Technical Reports Server (NTRS)

    Quinlan, Jesse R.; McDaniel, James C.; Drozda, Tomasz G.; Lacaze, Guilhem; Oefelein, Joseph

    2014-01-01

    An a priori investigation of the applicability of flamelet-based combustion models to dual-mode scramjet combustion was performed utilizing Reynolds-averaged simulations (RAS). For this purpose, the HIFiRE Direct Connect Rig (HDCR) flowpath, fueled with a JP-7 fuel surrogate and operating in dual- and scram-mode was considered. The chemistry of the JP-7 fuel surrogate was modeled using a 22 species, 18-step chemical reaction mechanism. Simulation results were compared to experimentally-obtained, time-averaged, wall pressure measurements to validate the RAS solutions. The analysis of the dual-mode operation of this flowpath showed regions of predominately non-premixed, high-Damkohler number, combustion. Regions of premixed combustion were also present but associated with only a small fraction of the total heat-release in the flow. This is in contrast to the scram-mode operation, where a comparable amount of heat is released from non-premixed and premixed combustion modes. Representative flamelet boundary conditions were estimated by analyzing probability density functions for temperature and pressure for pure fuel and oxidizer conditions. The results of the present study reveal the potential for a flamelet model to accurately model the combustion processes in the HDCR and likely other high-speed flowpaths of engineering interest.

  17. Improving image reconstruction of bioluminescence imaging using a priori information from ultrasound imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jayet, Baptiste; Ahmad, Junaid; Taylor, Shelley L.; Hill, Philip J.; Dehghani, Hamid; Morgan, Stephen P.

    2017-03-01

    Bioluminescence imaging (BLI) is a commonly used imaging modality in biology to study cancer in vivo in small animals. Images are generated using a camera to map the optical fluence emerging from the studied animal, then a numerical reconstruction algorithm is used to locate the sources and estimate their sizes. However, due to the strong light scattering properties of biological tissues, the resolution is very limited (around a few millimetres). Therefore obtaining accurate information about the pathology is complicated. We propose a combined ultrasound/optics approach to improve accuracy of these techniques. In addition to the BLI data, an ultrasound probe driven by a scanner is used for two main objectives. First, to obtain a pure acoustic image, which provides structural information of the sample. And second, to alter the light emission by the bioluminescent sources embedded inside the sample, which is monitored using a high speed optical detector (e.g. photomultiplier tube). We will show that this last measurement, used in conjunction with the ultrasound data, can provide accurate localisation of the bioluminescent sources. This can be used as a priori information by the numerical reconstruction algorithm, greatly increasing the accuracy of the BLI image reconstruction as compared to the image generated using only BLI data.

  18. Double-difference traveltime tomography with edge-preserving regularization and a priori interfaces

    NASA Astrophysics Data System (ADS)

    Lin, Youzuo; Syracuse, Ellen M.; Maceira, Monica; Zhang, Haijiang; Larmat, Carene

    2015-05-01

    Conventional traveltime seismic tomography methods with Tikhonov regularization (L2 norm) typically produce smooth models, but these models may be inappropriate when subsurface structure contains discontinuous features, such as faults or fractures, indicating that tomographic models should contain sharp boundaries. For this reason, we develop a double-difference (DD) traveltime tomography method that uses a modified total-variation regularization scheme incorporated with a priori information on interfaces to preserve sharp property contrasts and obtain accurate inversion results. In order to solve the inversion problem, we employ an alternating minimization method to decouple the original DD tomography problem into two separate subproblems: a conventional DD tomography with Tikhonov regularization and a L2 total-variation inversion. We use the LSQR linear solver to solve the Tikhonov inversion and the split-Bregman iterative method to solve the total-variation inversion. Through our numerical examples, we show that our new DD tomography method yields more accurate results than the conventional DD tomography method at almost the same computational cost.

  19. A priori complete active space self consistent field localized orbitals: an application on linear polyenes

    NASA Astrophysics Data System (ADS)

    Angeli, Celestino; Sparta, Manuel; Cimiraglia, Renzo

    2006-03-01

    A recently proposed a priori localization technique is used to exploit the possibility to reduce the number of active orbitals in a Complete Active Space Self Consistent Field calculation. The work relies on the fact that the new approach allows a strict control on the nature of the active orbitals and therefore makes it possible to include in the active space only the relevant orbitals. The idea is tested on the calculation of the energy barrier for rigid rotation of linear polyenes. In order to obtain a relevant set of data, a number of possible rotations around double bonds have been considered in the ethylene, butadiene, hexatriene, octatetraene, decapentaene, dodecahexaene molecules. The possibility to reduce the dimension of the active space has been investigated, considering for each possible rotation different active spaces ranging from the minimal dimension of 2 electrons in 2 π orbitals to the π-complete space. The results show that the rigid isomerization in the polyene molecules can be described with a negligible loss in accuracy with active spaces no larger than ten orbitals and ten electrons. In the special case of the rotation around the terminal double bond, the space can be further reduced to six orbitals and six electrons with a large decrease of the computational cost. An interesting summation rule has been found and verified for the stabilization of the energy barriers as a function of the dimension of the conjugated lateral chains and of the dimension of the active space.

  20. Do we use a priori knowledge of gravity when making elbow rotations?

    PubMed

    Pinter, Ilona J; van Soest, Arthur J; Bobbert, Maarten F; Smeets, Jeroen B J

    2012-03-01

    In this study, we aim to investigate whether motor commands, emanating from movement planning, are customized to movement orientation relative to gravity from the first trial on. Participants made fast point-to-point elbow flexions and extensions in the transverse plane. We compared movements that had been practiced in reclined orientation either against or with gravity with the same movement relative to the body axis made in the upright orientation (neutral compared to gravity). For each movement type, five rotations from reclined to upright orientation were made. For each rotation, we analyzed the first trial in upright orientation and the directly preceding trial in reclined orientation. Additionally, we analyzed the last five trials of a 30-trial block in upright position and compared these trials with the first trials in upright orientation. Although participants moved fast, gravitational torques were substantial. The change in body orientation affected movement planning: we found a decrease in peak angular velocity and a decrease in amplitude for the first trials made in the upright orientation, regardless of whether the previous movements in reclined orientation were made against or with gravity. We found that these decreases disappeared after participants familiarized themselves with moving in upright position in a 30-trial block. These results indicate that participants used a general strategy, corresponding to the strategy observed in situations with unreliable or limited information on external conditions. From this, we conclude that during movement planning, a priori knowledge of gravity was not used to specifically customize motor commands for the neutral gravity condition.

  1. SPARSE-A subgrid particle averaged Reynolds stress equivalent model: testing with a priori closure.

    PubMed

    Davis, Sean L; Jacobs, Gustaaf B; Sen, Oishik; Udaykumar, H S

    2017-03-01

    A Lagrangian particle cloud model is proposed that accounts for the effects of Reynolds-averaged particle and turbulent stresses and the averaged carrier-phase velocity of the subparticle cloud scale on the averaged motion and velocity of the cloud. The SPARSE (subgrid particle averaged Reynolds stress equivalent) model is based on a combination of a truncated Taylor expansion of a drag correction function and Reynolds averaging. It reduces the required number of computational parcels to trace a cloud of particles in Eulerian-Lagrangian methods for the simulation of particle-laden flow. Closure is performed in an a priori manner using a reference simulation where all particles in the cloud are traced individually with a point-particle model. Comparison of a first-order model and SPARSE with the reference simulation in one dimension shows that both the stress and the averaging of the carrier-phase velocity on the cloud subscale affect the averaged motion of the particle. A three-dimensional isotropic turbulence computation shows that only one computational parcel is sufficient to accurately trace a cloud of tens of thousands of particles.

  2. A Priori Attitudes Predict Amniocentesis Uptake in Women of Advanced Maternal Age: A Pilot Study.

    PubMed

    Grinshpun-Cohen, Julia; Miron-Shatz, Talya; Rhee-Morris, Laila; Briscoe, Barbara; Pras, Elon; Towner, Dena

    2015-01-01

    Amniocentesis is an invasive procedure performed during pregnancy to determine, among other things, whether the fetus has Down syndrome. It is often preceded by screening, which gives a probabilistic risk assessment. Thus, ample information is conveyed to women with the goal to inform their decisions. This study examined the factors that predict amniocentesis uptake among pregnant women of advanced maternal age (older than 35 years old at the time of childbirth). Participants filled out a questionnaire regarding risk estimates, demographics, and attitudes on screening and pregnancy termination before their first genetic counseling appointment and were followed up to 24 weeks of gestation. Findings show that women's decisions are not always informed by screening results or having a medical indication. Psychological factors measured at the beginning of pregnancy: amniocentesis risk tolerance, pregnancy termination tolerance, and age risk perception affected amniocentesis uptake. Although most women thought that screening for Down syndrome risk would inform their decision, they later stated other reasons for screening, such as preparing for the possibility of a child with special needs. Findings suggest that women's decisions regarding amniocentesis are driven not only by medical factors, but also by a priori attitudes. The authors believe that these should be addressed in the dialogue on women's informed use of prenatal tests.

  3. The application of a priori structural information based regularization in image reconstruction in magnetic induction tomography

    NASA Astrophysics Data System (ADS)

    Dekdouk, B.; Ktistis, C.; Yin, W.; Armitage, D. W.; Peyton, A. J.

    2010-04-01

    Magnetic induction tomography (MIT) is a non-invasive contactless modality that could be capable of imaging the conductivity distribution of biological tissues. In this paper we consider the possibility of using absolute MIT voltage measurements for monitoring the progress of a peripheral hemorrhagic stroke in a human brain. The pathology is modelled as a local blood accumulation in the white matter. The solution of the MIT inverse problem is nonlinear and ill-posed and hence requires the use of a regularisation method. In this paper, we describe the construction and present the performance of a regularisation matrix based on a priori structural information of the head tissues obtained from a very recent MRI scan. The method takes the MRI scan as an initial state of the stroke and constructs a learning set containing the possible conductivity distributions of the current state of the stroke. This data is used to calculate an approximation of the covariance matrix and then a subspace is constructed using principal component analysis (PCA). It is shown by simulations the method is capable of producing a representative reconstruction of a stroke compared to smoothing Tikhonov regularization in a simplified model of the head.

  4. KIR Genes and Patterns Given by the A Priori Algorithm: Immunity for Haematological Malignancies.

    PubMed

    Rodríguez-Escobedo, J Gilberto; García-Sepúlveda, Christian A; Cuevas-Tello, Juan C

    2015-01-01

    Killer-cell immunoglobulin-like receptors (KIRs) are membrane proteins expressed by cells of innate and adaptive immunity. The KIR system consists of 17 genes and 614 alleles arranged into different haplotypes. KIR genes modulate susceptibility to haematological malignancies, viral infections, and autoimmune diseases. Molecular epidemiology studies rely on traditional statistical methods to identify associations between KIR genes and disease. We have previously described our results by applying support vector machines to identify associations between KIR genes and disease. However, rules specifying which haplotypes are associated with greater susceptibility to malignancies are lacking. Here we present the results of our investigation into the rules governing haematological malignancy susceptibility. We have studied the different haplotypic combinations of 17 KIR genes in 300 healthy individuals and 43 patients with haematological malignancies (25 with leukaemia and 18 with lymphomas). We compare two machine learning algorithms against traditional statistical analysis and show that the "a priori" algorithm is capable of discovering patterns unrevealed by previous algorithms and statistical approaches.

  5. Source apportionment of urban air pollutants using constrained receptor models with a priori profile information.

    PubMed

    Liao, Ho-Tang; Yau, Yu-Chen; Huang, Chun-Sheng; Chen, Nathan; Chow, Judith C; Watson, John G; Tsai, Shih-Wei; Chou, Charles C-K; Wu, Chang-Fu

    2017-08-01

    Exposure to air pollutants such as volatile organic compounds (VOCs) and fine particulate matter (PM2.5) are associated with adverse health effects. This study applied multiple time resolution data of hourly VOCs and 24-h PM2.5 to a constrained Positive Matrix Factorization (PMF) model for source apportionment in Taipei, Taiwan. Ninety-two daily PM2.5 samples and 2208 hourly VOC measurements were collected during four seasons in 2014 and 2015. With some a priori information, we used different procedures to constrain retrieved factors toward realistic sources. A total of nine source factors were identified as: natural gas/liquefied petroleum gas (LPG) leakage, solvent use/industrial process, contaminated marine aerosol, secondary aerosol/long-range transport, oil combustion, traffic related, evaporative gasoline emission, gasoline exhaust, and soil dust. Results showed that solvent use/industrial process was the largest contributor (19%) to VOCs while the largest contributor to PM2.5 mass was secondary aerosol/long-range transport (57%). A robust regression analysis showed that secondary aerosol was mostly contributed by regional transport related factor (25%). Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Acoustic attenuation imaging of tissue bulk properties with a priori information

    PubMed Central

    Hooi, Fong Ming; Kripfgans, Oliver; Carson, Paul L.

    2016-01-01

    Attenuation of ultrasound waves traversing a medium is not only a result of absorption and scattering within a given tissue, but also of coherent scattering, including diffraction, refraction, and reflection of the acoustic wave at tissue boundaries. This leads to edge enhancement and other artifacts in most reconstruction algorithms, other than 3D wave migration with currently impractical, implementations. The presented approach accounts for energy loss at tissue boundaries by normalizing data based on variable sound speed, and potential density, of the medium using a k-space wave solver. Coupled with a priori knowledge of major sound speed distributions, physical attenuation values within broad ranges, and the assumption of homogeneity within segmented regions, an attenuation image representative of region bulk properties is constructed by solving a penalized weighted least squares optimization problem. This is in contradistinction to absorption or to conventional attenuation coefficient based on overall insertion loss with strong dependence on sound speed and impedance mismatches at tissue boundaries. This imaged property will be referred to as the bulk attenuation coefficient. The algorithm is demonstrated on an opposed array setup, with mean-squared-error improvements from 0.6269 to 0.0424 (dB/cm/MHz)2 for a cylindrical phantom, and 0.1622 to 0.0256 (dB/cm/MHz)2 for a windowed phantom. PMID:27914403

  7. Improving diffuse optical tomography with structural a priori from fluorescence diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Ma, Wenjuan; Gao, Feng; Duan, Linjing; Zhu, Qingzhen; Wang, Xin; Zhang, Wei; Wu, Linhui; Yi, Xi; Zhao, Huijuan

    2012-03-01

    We obtain absorption and scattering reconstructed images by incorporating a priori information of target location obtained from fluorescence diffuse optical tomography (FDOT) into the diffuse optical tomography (DOT). The main disadvantage of DOT lies in the low spatial resolution resulting from highly scattering nature of tissue in the near-infrared (NIR), but one can use it to monitor hemoglobin concentration and oxygen saturation simultaneously, as well as several other cheomphores such as water, lipids, and cytochrome-c-oxidase. Up to date, extensive effort has been made to integrate DOT with other imaging modalities such as MRI, CT, to obtain accurate optical property maps of the tissue. However, the experimental apparatus is intricate. In this study, DOT image reconstruction algorithm that incorporates a prior structural information provided by FDOT is investigated in an attempt to optimize recovery of a simulated optical property distribution. By use of a specifically designed multi-channel time-correlated single photon counting system, the proposed scheme in a transmission mode is experimentally validated to achieve simultaneous reconstruction of the fluorescent yield, lifetime, absorption and scattering coefficient. The experimental results demonstrate that the quantitative recovery of the tumor optical properties has doubled and the spatial resolution improves as well by applying the new improved method.

  8. A Priori Analyses of Three Subgrid-Scale Models for One-Parameter Families of Filters

    NASA Technical Reports Server (NTRS)

    Pruett, C. David; Adams, Nikolaus A.

    1998-01-01

    The decay of isotropic turbulence a compressible flow is examined by direct numerical simulation (DNS). A priori analyses of the DNS data are then performed to evaluate three subgrid-scale (SGS) models for large-eddy simulation (LES): a generalized Smagorinsky model (M1), a stress-similarity model (M2), and a gradient model (M3). The models exploit one-parameter second- or fourth-order filters of Pade type, which permit the cutoff wavenumber k(sub c) to be tuned independently of the grid increment (delta)x. The modeled (M) and exact (E) SGS-stresses are compared component-wise by correlation coefficients of the form C(E,M) computed over the entire three-dimensional fields. In general, M1 correlates poorly against exact stresses (C < 0.2), M3 correlates moderately well (C approx. 0.6), and M2 correlates remarkably well (0.8 < C < 1.0). Specifically, correlations C(E, M2) are high provided the grid and test filters are of the same order. Moreover, the highest correlations (C approx.= 1.0) result whenever the grid and test filters are identical (in both order and cutoff). Finally, present results reveal the exact SGS stresses obtained by grid filters of differing orders to be only moderately well correlated. Thus, in LES the model should not be specified independently of the filter.

  9. A quantum question order model supported by empirical tests of an a priori and precise prediction.

    PubMed

    Wang, Zheng; Busemeyer, Jerome R

    2013-10-01

    Question order effects are commonly observed in self-report measures of judgment and attitude. This article develops a quantum question order model (the QQ model) to account for four types of question order effects observed in literature. First, the postulates of the QQ model are presented. Second, an a priori, parameter-free, and precise prediction, called the QQ equality, is derived from these mathematical principles, and six empirical data sets are used to test the prediction. Third, a new index is derived from the model to measure similarity between questions. Fourth, we show that in contrast to the QQ model, Bayesian and Markov models do not generally satisfy the QQ equality and thus cannot account for the reported empirical data that support this equality. Finally, we describe the conditions under which order effects are predicted to occur, and we review a broader range of findings that are encompassed by these very same quantum principles. We conclude that quantum probability theory, initially invented to explain order effects on measurements in physics, appears to be a powerful natural explanation for order effects of self-report measures in social and behavioral sciences, too.

  10. The importance of using dynamical a-priori profiles for infrared O3 retrievals : the case of IASI.

    NASA Astrophysics Data System (ADS)

    Peiro, H.; Emili, E.; Le Flochmoen, E.; Barret, B.; Cariolle, D.

    2016-12-01

    Tropospheric ozone (O3) is a trace gas involved in the global greenhouse effect. To quantify its contribution to global warming, an accurate determination of O3 profiles is necessary. The instrument IASI (Infrared Atmospheric Sounding Interferometer), on board satellite MetOP-A, is the more sensitive sensor to tropospheric O3 with a high spatio-temporal coverage. Satellite retrievals are often based on the inversion of the measured radiance data with a variational approach. This requires an a priori profile and the correspondent error covariance matrix (COV) as ancillary input. Previous studies have shown some biases ( 20%) in IASI retrievals for tropospheric column in the Southern Hemisphere (SH). A possible source of errors is caused by the a priori profile. This study aims to i) build a dynamical a priori profile O3 with a Chemistry Transport Model (CTM), ii) integrate and to demonstrate the interest of this a priori profile in IASI retrievals.Global O3 profiles are retrieved from IASI radiances with the SOFRID (Software for a fast Retrieval of IASI Data) algorithm. It is based on the RTTOV (Radiative Transfer for TOVS) code and a 1D-Var retrieval scheme. Until now, a constant a priori profile was based on a combination of MOZAIC, WOUDC-SHADOZ and Aura/MLS data named here CLIM PR. The global CTM MOCAGE (Modèle de Chimie Atmosphérique à Grande Echelle) has been used with a linear O3 chemistry scheme to assimilate Microwave Limb Sounder (MLS) data. The model resolution of 2°x2°, with 60 sigma-hybrid vertical levels covering the stratosphere has been used. MLS level 2 products have been assimilated with a 4D-VAR variational algorithm to constrain stratospheric O3 and obtain high quality a priori profiles O3 above the tropopause. From this reanalysis, we built these profiles at a 6h frequency on a coarser resolution grid 10°x20° named MOCAGE+MLS PR.Statistical comparisons between retrievals and ozonesondes have shown better correlations and smaller biases for

  11. Development of a combined multifrequency MRI-DOT system for human breast imaging using a priori information

    NASA Astrophysics Data System (ADS)

    Thayer, David; Liu, Ning; Unlu, Burcin; Chen, Jeon-Hor; Su, Min-Ying; Nalcioglu, Orhan; Gulsen, Gultekin

    2010-02-01

    Breast cancer is a significant cause of mortality and morbidity among women with early diagnosis being vital to successful treatment. Diffuse Optical Tomography (DOT) is an emerging medical imaging modality that provides information that is complementary to current screening modalities such as MRI and mammography, and may improve the specificity in determining cancer malignancy. Using high-resolution anatomic images as a priori information improves the accuracy of DOT. Measurements are presented characterizing the performance of our system. Preliminary data is also shown illustrating the use of a priori MRI data in phantom studies.ä

  12. Allocating monitoring effort in the face of unknown unknowns

    USGS Publications Warehouse

    Wintle, B.A.; Runge, M.C.; Bekessy, S.A.

    2010-01-01

    There is a growing view that to make efficient use of resources, ecological monitoring should be hypothesis-driven and targeted to address specific management questions. 'Targeted' monitoring has been contrasted with other approaches in which a range of quantities are monitored in case they exhibit an alarming trend or provide ad hoc ecological insights. The second form of monitoring, described as surveillance, has been criticized because it does not usually aim to discern between competing hypotheses, and its benefits are harder to identify a priori. The alternative view is that the existence of surveillance data may enable rapid corroboration of emerging hypotheses or help to detect important 'unknown unknowns' that, if undetected, could lead to catastrophic outcomes or missed opportunities. We derive a model to evaluate and compare the efficiency of investments in surveillance and targeted monitoring. We find that a decision to invest in surveillance monitoring may be defensible if: (1) the surveillance design is more likely to discover or corroborate previously unknown phenomena than a targeted design and (2) the expected benefits (or avoided costs) arising from discovery are substantially higher than those arising from a well-planned targeted design. Our examination highlights the importance of being explicit about the objectives, costs and expected benefits of monitoring in a decision analytic framework. ?? 2010 Blackwell Publishing Ltd/CNRS.

  13. An algorithm for finding biologically significant features in microarray data based on a priori manifold learning.

    PubMed

    Hira, Zena M; Trigeorgis, George; Gillies, Duncan F

    2014-01-01

    Microarray databases are a large source of genetic data, which, upon proper analysis, could enhance our understanding of biology and medicine. Many microarray experiments have been designed to investigate the genetic mechanisms of cancer, and analytical approaches have been applied in order to classify different types of cancer or distinguish between cancerous and non-cancerous tissue. However, microarrays are high-dimensional datasets with high levels of noise and this causes problems when using machine learning methods. A popular approach to this problem is to search for a set of features that will simplify the structure and to some degree remove the noise from the data. The most widely used approach to feature extraction is principal component analysis (PCA) which assumes a multivariate Gaussian model of the data. More recently, non-linear methods have been investigated. Among these, manifold learning algorithms, for example Isomap, aim to project the data from a higher dimensional space onto a lower dimension one. We have proposed a priori manifold learning for finding a manifold in which a representative set of microarray data is fused with relevant data taken from the KEGG pathway database. Once the manifold has been constructed the raw microarray data is projected onto it and clustering and classification can take place. In contrast to earlier fusion based methods, the prior knowledge from the KEGG databases is not used in, and does not bias the classification process--it merely acts as an aid to find the best space in which to search the data. In our experiments we have found that using our new manifold method gives better classification results than using either PCA or conventional Isomap.

  14. An a priori DNS study of the shadow-position mixing model

    DOE PAGES

    Zhao, Xin -Yu; Bhagatwala, Ankit; Chen, Jacqueline H.; ...

    2016-01-15

    In this study, the modeling of mixing by molecular diffusion is a central aspect for transported probability density function (tPDF) methods. In this paper, the newly-proposed shadow position mixing model (SPMM) is examined, using a DNS database for a temporally evolving di-methyl ether slot jet flame. Two methods that invoke different levels of approximation are proposed to extract the shadow displacement (equivalent to shadow position) from the DNS database. An approach for a priori analysis of the mixing-model performance is developed. The shadow displacement is highly correlated with both mixture fraction and velocity, and the peak correlation coefficient of themore » shadow displacement and mixture fraction is higher than that of the shadow displacement and velocity. This suggests that the composition-space localness is reasonably well enforced by the model, with appropriate choices of model constants. The conditional diffusion of mixture fraction and major species from DNS and from SPMM are then compared, using mixing rates that are derived by matching the mixture fraction scalar dissipation rates. Good qualitative agreement is found, for the prediction of the locations of zero and maximum/minimum conditional diffusion locations for mixture fraction and individual species. Similar comparisons are performed for DNS and the IECM (interaction by exchange with the conditional mean) model. The agreement between SPMM and DNS is better than that between IECM and DNS, in terms of conditional diffusion iso-contour similarities and global normalized residual levels. It is found that a suitable value for the model constant c that controls the mixing frequency can be derived using the local normalized scalar variance, and that the model constant a controls the localness of the model. A higher-Reynolds-number test case is anticipated to be more appropriate to evaluate the mixing models, and stand-alone transported PDF simulations are required to more fully enforce

  15. An a priori DNS study of the shadow-position mixing model

    SciTech Connect

    Zhao, Xin -Yu; Bhagatwala, Ankit; Chen, Jacqueline H.; Haworth, Daniel C.; Pope, Stephen B.

    2016-01-15

    In this study, the modeling of mixing by molecular diffusion is a central aspect for transported probability density function (tPDF) methods. In this paper, the newly-proposed shadow position mixing model (SPMM) is examined, using a DNS database for a temporally evolving di-methyl ether slot jet flame. Two methods that invoke different levels of approximation are proposed to extract the shadow displacement (equivalent to shadow position) from the DNS database. An approach for a priori analysis of the mixing-model performance is developed. The shadow displacement is highly correlated with both mixture fraction and velocity, and the peak correlation coefficient of the shadow displacement and mixture fraction is higher than that of the shadow displacement and velocity. This suggests that the composition-space localness is reasonably well enforced by the model, with appropriate choices of model constants. The conditional diffusion of mixture fraction and major species from DNS and from SPMM are then compared, using mixing rates that are derived by matching the mixture fraction scalar dissipation rates. Good qualitative agreement is found, for the prediction of the locations of zero and maximum/minimum conditional diffusion locations for mixture fraction and individual species. Similar comparisons are performed for DNS and the IECM (interaction by exchange with the conditional mean) model. The agreement between SPMM and DNS is better than that between IECM and DNS, in terms of conditional diffusion iso-contour similarities and global normalized residual levels. It is found that a suitable value for the model constant c that controls the mixing frequency can be derived using the local normalized scalar variance, and that the model constant a controls the localness of the model. A higher-Reynolds-number test case is anticipated to be more appropriate to evaluate the mixing models, and stand-alone transported PDF simulations are required to more fully enforce localness and

  16. A review of a priori regression models for warfarin maintenance dose prediction.

    PubMed

    Francis, Ben; Lane, Steven; Pirmohamed, Munir; Jorgensen, Andrea

    2014-01-01

    A number of a priori warfarin dosing algorithms, derived using linear regression methods, have been proposed. Although these dosing algorithms may have been validated using patients derived from the same centre, rarely have they been validated using a patient cohort recruited from another centre. In order to undertake external validation, two cohorts were utilised. One cohort formed by patients from a prospective trial and the second formed by patients in the control arm of the EU-PACT trial. Of these, 641 patients were identified as having attained stable dosing and formed the dataset used for validation. Predicted maintenance doses from six criterion fulfilling regression models were then compared to individual patient stable warfarin dose. Predictive ability was assessed with reference to several statistics including the R-square and mean absolute error. The six regression models explained different amounts of variability in the stable maintenance warfarin dose requirements of the patients in the two validation cohorts; adjusted R-squared values ranged from 24.2% to 68.6%. An overview of the summary statistics demonstrated that no one dosing algorithm could be considered optimal. The larger validation cohort from the prospective trial produced more consistent statistics across the six dosing algorithms. The study found that all the regression models performed worse in the validation cohort when compared to the derivation cohort. Further, there was little difference between regression models that contained pharmacogenetic coefficients and algorithms containing just non-pharmacogenetic coefficients. The inconsistency of results between the validation cohorts suggests that unaccounted population specific factors cause variability in dosing algorithm performance. Better methods for dosing that take into account inter- and intra-individual variability, at the initiation and maintenance phases of warfarin treatment, are needed.

  17. A priori typology-based prediction of benthic macroinvertebrate fauna for ecological classification of rivers.

    PubMed

    Aroviita, Jukka; Koskenniemi, Esa; Kotanen, Juho; Hämäläinen, Heikki

    2008-11-01

    We evaluated a simple bioassessment method based on a priori river typology to predict benthic macroinvertebrate fauna in riffle sites of rivers in the absence of human influence. Our approach predicted taxon lists specific to four river types differing in catchment area with a method analogous to the site-specific RIVPACS-type models. The reference sites grouped in accordance with their type in NMS ordination, indicating that the typology efficiently accounted for natural variation in macroinvertebrate assemblages. Compared with a null model, typology greatly increased the precision of prediction and sensitivity to detect human impairment and strengthened the correlation of the ratio of observed-to-expected number of predicted taxa (O/E) with the measured stressor variables. The performance of the typology-based approach was equal to that of a RIVPACS-type predictive model that we developed. Exclusion of rarest taxa with low occurrence probabilities improved the performance of both approaches by all criteria. With an increasing inclusion threshold of occurrence probability, especially the predictive model sensitivity first increased but then decreased. Many common taxa with intermediate type-specific occurrence probabilities were consistently missing from impacted sites, a result suggesting that these taxa may be especially important in detecting human disturbances. We conclude that if a typology-based approach such as that suggested by the European Union's Water Framework Directive is required, the O/E ratio of type-specific taxa can be a useful metric for assessment of the status of riffle macroinvertebrate communities. Successful application of the approach, however, requires biologically meaningful river types with a sufficient pool of reference sites for each type.

  18. Limited angle breast ultrasound tomography with a priori information and artifact removal

    NASA Astrophysics Data System (ADS)

    Jintamethasawat, Rungroj; Zhu, Yunhao; Kripfgans, Oliver D.; Yuan, Jie; Goodsitt, Mitchell M.; Carson, Paul L.

    2017-03-01

    In B-mode images from dual-sided ultrasound, it has been shown that by delineating structures suspected of being relatively homogeneous, one can enhance limited angle tomography to produce speed of sound images in the same view as X-ray Digital Breast Tomography (DBT). This could allow better breast cancer detection and discrimination, as well as improved registration of the ultrasound and X-ray images, because of the similarity of SOS and X-ray contrast in the breast. However, this speed of sound reconstruction method relies strongly on B-mode or other reflection mode segmentation. If that information is limited or incorrect, artifacts will appear in the reconstructed images. Therefore, the iterative speed of sound reconstruction algorithm has been modified in a manner of simultaneously utilizing the image segmentations and removing most artifacts. The first step of incorporating a priori information is solved by any nonlinearnonconvex optimization method while artifact removal is accomplished by employing the fast split Bregman method to perform total-variation (TV) regularization for image denoising. The proposed method was demonstrated in simplified simulations of our dual-sided ultrasound scanner. To speed these computations two opposed 40-element ultrasound linear arrays with 0.5 MHz center frequency were simulated for imaging objects in a uniform background. The proposed speed of sound reconstruction method worked well with both bent-ray and full-wave inversion methods. This is also the first demonstration of successful full-wave medical ultrasound tomography in the limited angle geometry. Presented results lend credibility to a possible translation of this method to clinical breast imaging.

  19. AN A PRIORI INVESTIGATION OF ASTROPHYSICAL FALSE POSITIVES IN GROUND-BASED TRANSITING PLANET SURVEYS

    SciTech Connect

    Evans, Tom M.; Sackett, Penny D.

    2010-03-20

    Astrophysical false positives due to stellar eclipsing binaries pose one of the greatest challenges to ground-based surveys for transiting hot Jupiters. We have used known properties of multiple star systems and hot Jupiter systems to predict, a priori, the number of such false detections and the number of genuine planet detections recovered in two hypothetical but realistic ground-based transit surveys targeting fields close to the galactic plane (b {approx} 10{sup 0}): a shallow survey covering a magnitude range 10 < V < 13 and a deep survey covering a magnitude range 15 < V < 19. Our results are consistent with the commonly reported experience of false detections outnumbering planet detections by a factor of {approx}10 in shallow surveys, while in our synthetic deep survey we find {approx}1-2 false detections for every planet detection. We characterize the eclipsing binary configurations that are most likely to cause false detections and find that they can be divided into three main types: (1) two dwarfs undergoing grazing transits, (2) two dwarfs undergoing low-latitude transits in which one component has a substantially smaller radius than the other, and (3) two eclipsing dwarfs blended with one or more physically unassociated foreground stars. We also predict that a significant fraction of hot Jupiter detections are blended with the light from other stars, showing that care must be taken to identify the presence of any unresolved neighbors in order to obtain accurate estimates of planetary radii. This issue is likely to extend to terrestrial planet candidates in the CoRoT and Kepler transit surveys, for which neighbors of much fainter relative brightness will be important.

  20. Lost in space: Onboard star identification using CCD star tracker data without an a priori attitude

    NASA Technical Reports Server (NTRS)

    Ketchum, Eleanor A.; Tolson, Robert H.

    1993-01-01

    There are many algorithms in use today which determine spacecraft attitude by identifying stars in the field of view of a star tracker. Some methods, which date from the early 1960's, compare the angular separation between observed stars with a small catalog. In the last 10 years, several methods have been developed which speed up the process and reduce the amount of memory needed, a key element to onboard attitude determination. However, each of these methods require some a priori knowledge of the spacecraft attitude. Although the Sun and magnetic field generally provide the necessary coarse attitude information, there are occasions when a spacecraft could get lost when it is not prudent to wait for sunlight. Also, the possibility of efficient attitude determination using only the highly accurate CCD star tracker could lead to fully autonomous spacecraft attitude determination. The need for redundant coarse sensors could thus be eliminated at substantial cost reduction. Some groups have extended their algorithms to implement a computation intense full sky scan. Some require large data bases. Both storage and speed are concerns for autonomous onboard systems. Neural network technology is even being explored by some as a possible solution, but because of the limited number of patterns that can be stored and large overhead, nothing concrete has resulted from these efforts. This paper presents an algorithm which, by descretizing the sky and filtering by visual magnitude of the brightness observed star, speeds up the lost in space star identification process while reducing the amount of necessary onboard computer storage compared to existing techniques.

  1. Lost in space: Onboard star identification using CCD star tracker data without an a priori attitude

    NASA Technical Reports Server (NTRS)

    Ketchum, Eleanor A.; Tolson, Robert H.

    1993-01-01

    There are many algorithms in use today which determine spacecraft attitude by identifying stars in the field of view of a star tracker. Some methods, which date from the early 1960's, compare the angular separation between observed stars with a small catalog. In the last 10 years, several methods have been developed which speed up the process and reduce the amount of memory needed, a key element to onboard attitude determination. However, each of these methods require some a priori knowledge of the spacecraft attitude. Although the Sun and magnetic field generally provide the necessary coarse attitude information, there are occasions when a spacecraft could get lost when it is not prudent to wait for sunlight. Also, the possibility of efficient attitude determination using only the highly accurate CCD star tracker could lead to fully autonomous spacecraft attitude determination. The need for redundant coarse sensors could thus be eliminated at substantial cost reduction. Some groups have extended their algorithms to implement a computation intense full sky scan. Some require large data bases. Both storage and speed are concerns for autonomous onboard systems. Neural network technology is even being explored by some as a possible solution, but because of the limited number of patterns that can be stored and large overhead, nothing concrete has resulted from these efforts. This paper presents an algorithm which, by descretizing the sky and filtering by visual magnitude of the brightness observed star, speeds up the lost in space star identification process while reducing the amount of necessary onboard computer storage compared to existing techniques.

  2. The utility of evolutionary psychology for generating novel, specific, and a priori hypotheses about psychopathology in a parsimonious fashion: reply to Hankin (2013).

    PubMed

    Martel, Michelle M

    2013-11-01

    The comment of Hankin (2013) elucidated several strengths of the target article (Martel, 2013), in which I reviewed extant literature on sex differences in common childhood-onset externalizing and adolescent-onset internalizing disorders. Hankin also raised important questions about the utility of evolutionary psychological principles, particularly those of sexual selection, to generate novel, specific, and a priori hypotheses about sex differences in common forms of psychopathology. I acknowledge these points, and I contend that a metatheory derived from evolutionary psychological principles is quite useful in 2 ways. First, it provides a parsimonious framework for understanding sex differences across multiple levels of analysis (e.g., hormones, gene by environment interactions, dispositional traits, behavioral and emotional symptoms). Second, it provides a framework for the generation of novel, specific, and a priori hypotheses such as those elucidated in my review. Existing disorder-specific theories cannot do as well in serving these functions. The pursuit of metatheories that both organize existing findings and generate novel cross-disorder hypotheses is crucial for ongoing progress in psychological science. Evolutionary psychology provides one such fruitful metatheory. © 2013 American Psychological Association

  3. Musical Probabilities, Abductive Reasoning, and Brain Mechanisms: Extended Perspective of "A Priori" Listening to Music within the Creative Cognition Approach

    ERIC Educational Resources Information Center

    Schmidt, Sebastian; Troge, Thomas A.; Lorrain, Denis

    2013-01-01

    A theory of listening to music is proposed. It suggests that, for listeners, the process of prediction is the starting point to experiencing music. This implies that perception of music starts through both a predisposed and an experience-based extrapolation into the future (this is labeled "a priori" listening). Indications for this…

  4. Musical Probabilities, Abductive Reasoning, and Brain Mechanisms: Extended Perspective of "A Priori" Listening to Music within the Creative Cognition Approach

    ERIC Educational Resources Information Center

    Schmidt, Sebastian; Troge, Thomas A.; Lorrain, Denis

    2013-01-01

    A theory of listening to music is proposed. It suggests that, for listeners, the process of prediction is the starting point to experiencing music. This implies that perception of music starts through both a predisposed and an experience-based extrapolation into the future (this is labeled "a priori" listening). Indications for this…

  5. A priori patient-specific collision avoidance in radiotherapy using consumer grade depth cameras.

    PubMed

    Cardan, Rex A; Popple, Richard A; Fiveash, John

    2017-07-01

    In this study, we demonstrate and evaluate a low cost, fast, and accurate avoidance framework for radiotherapy treatments. Furthermore, we provide an implementation which is patient specific and can be implemented during the normal simulation process. Four patients and a treatment unit were scanned with a set of consumer depth cameras to create a polygon mesh of each object. Using a fast polygon interference algorithm, the models were virtually collided to map out feasible treatment positions of the couch and gantry. The actual physical collision space was then mapped in the treatment room by moving the gantry and couch until a collision occurred with either the patient or hardware. The physical and virtual collision spaces were then compared to determine the accuracy of the system. To improve the collision predictions, a buffer geometry was added to the scanned gantry mesh and performance was assessed as a function of buffer thickness. Each patient was optically scanned during simulation in less than 1 min. The average time to virtually map the collision space for 64, 800 gantry/couch states was 5.40 ± 2.88 s. The system had an average raw accuracy and negative prediction rate (NPR) across all patients of 97.3% ± 2.4% and 96.9% ± 2.2% respectively. Using a polygon buffer of 6 cm over the gantry geometry, the NPR was raised to unity for all patients, signifying the detection of all collision events. However, the average accuracy fell from 95.3% ± 3.1% to 91.5% ± 3.6% between the 3 and 6 cm buffer as more false positives were detected. We successfully demonstrated a fast and low cost framework which can map an entire collision space a priori for a given patient during the time of simulation. All collisions can be avoided using polygon interference, but a polygon buffer may be required to account for geometric uncertainties of scanned objects. © 2017 American Association of Physicists in Medicine.

  6. Optical tomographic imaging of activation of the infant auditory cortex using perturbation Monte Carlo with anatomical a priori information

    NASA Astrophysics Data System (ADS)

    Heiskala, Juha; Kotilahti, Kalle; Lipiäinen, Lauri; Hiltunen, Petri; Grant, P. Ellen; Nissilä, Ilkka

    2007-07-01

    We have developed a perturbation Monte Carlo method for calculating forward and inverse solutions to the optical tomography imaging problem in the presence of anatomical a priori information. The method uses frequency domain data. In the present work, we consider the problem of imaging hemodynamic changes due to brain activation in the infant brain. We test finite element method and Monte Carlo based implementations using a homogeneous model with the exterior of the domain warped to match digitized points on the skin. With the perturbation Monte Carlo model, we also test a heterogeneous model based on anatomical a priori information derived from a previously recorded infant T1 magnetic resonance (MR) image. Our simulations show that the anatomical information improves the accuracy of reconstructions quite significantly even if the anatomical MR images are based on another infant. This suggests that significant benefits can be obtained by the use of generic infant brain atlas information in near-infrared spectroscopy and optical tomography studies.

  7. Novel post-Doppler STAP with a priori knowledge information for traffic monitoring applications: basic idea and first results

    NASA Astrophysics Data System (ADS)

    da Silva, André B. C.; Baumgartner, Stefan V.

    2017-09-01

    This paper presents a novel a priori knowledge-based algorithm for traffic monitoring applications. The powerful post-Doppler space-time adaptive processing (PD STAP) is combined with a known road network obtained from the freely available OpenStreetMap (OSM) database. The road information is applied after the PD STAP for recognizing and rejecting false detections, and moreover, for repositioning the vehicles detected in the vicinity of the roads. The algorithm presents great potential for real-time processing, decreased hardware complexity and low costs compared to state-of-the-art systems. The processor was tested using real multi-channel data acquired by DLR's airborne system F-SAR. The experimental results are shown and discussed, and the novelties are highlighted (e.g., the benefits of using a priori knowledge information).

  8. A priori error estimates for an hp-version of the discontinuous Galerkin method for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Bey, Kim S.; Oden, J. Tinsley

    1993-01-01

    A priori error estimates are derived for hp-versions of the finite element method for discontinuous Galerkin approximations of a model class of linear, scalar, first-order hyperbolic conservation laws. These estimates are derived in a mesh dependent norm in which the coefficients depend upon both the local mesh size h(sub K) and a number p(sub k) which can be identified with the spectral order of the local approximations over each element.

  9. Tomographic inversion of time-domain resistivity and chargeability data for the investigation of landfills using a priori information.

    PubMed

    De Donno, Giorgio; Cardarelli, Ettore

    2017-01-01

    In this paper, we present a new code for the modelling and inversion of resistivity and chargeability data using a priori information to improve the accuracy of the reconstructed model for landfill. When a priori information is available in the study area, we can insert them by means of inequality constraints on the whole model or on a single layer or assigning weighting factors for enhancing anomalies elongated in the horizontal or vertical directions. However, when we have to face a multilayered scenario with numerous resistive to conductive transitions (the case of controlled landfills), the effective thickness of the layers can be biased. The presented code includes a model-tuning scheme, which is applied after the inversion of field data, where the inversion of the synthetic data is performed based on an initial guess, and the absolute difference between the field and synthetic inverted models is minimized. The reliability of the proposed approach has been supported in two real-world examples; we were able to identify an unauthorized landfill and to reconstruct the geometrical and physical layout of an old waste dump. The combined analysis of the resistivity and chargeability (normalised) models help us to remove ambiguity due to the presence of the waste mass. Nevertheless, the presence of certain layers can remain hidden without using a priori information, as demonstrated by a comparison of the constrained inversion with a standard inversion. The robustness of the above-cited method (using a priori information in combination with model tuning) has been validated with the cross-section from the construction plans, where the reconstructed model is in agreement with the original design. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. A priori parameter estimates for global hydrological modeling using geographically based information: Application of the CREST hydrologic model

    NASA Astrophysics Data System (ADS)

    Gao, Z.; Zhang, K.; Xue, X.; Huang, J.; Hong, Y.

    2016-12-01

    Floods are among the most common natural disasters with worldwide impacts that cause significant humanitarian and economic negative consequences. The increasing availability of satellite-based precipitation estimates and geospatial datasets with global coverage and improved temporal resolutions has enhanced our capability of forecasting floods and monitoring water resources across the world. This study presents an approach combing physically based and empirical methods for a-priori parameter estimates and a parameter dataset for the Coupled Routing and Excess Storage (CREST) hydrological model at the global scale. This approach takes advantage of geographic information such as topography, land cover, and soil properties to derive the distributed parameter values across the world. The main objective of this study is to evaluate the utility of a-priori parameter estimates to improve the performance of the CREST distributed hydrologic model and enable its prediction at poorly gauged or ungauged catchments. Using the CREST hydrologic model, several typical river basins in different continents were selected to serve as test areas. The results show that the simulated daily stream flows using the parameters derived from geographically based information outperform the results using the lumped parameters. Overall, this early study highlights that a priori parameter estimates for hydrologic model warrants improved model predictive capability in ungauged basins at regional to global scales.

  11. Evaluating a Priori Ozone Profile Information Used in TEMPO (Tropospheric Emissions: Monitoring of Pollution) Tropospheric Ozone Retrievals

    NASA Technical Reports Server (NTRS)

    Johnson, Matthew Stephen

    2017-01-01

    A primary objective for TOLNet is the evaluation and validation of space-based tropospheric O3 retrievals from future systems such as the Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite. This study is designed to evaluate the tropopause-based O3 climatology (TB-Clim) dataset which will be used as the a priori profile information in TEMPO O3 retrievals. This study also evaluates model simulated O3 profiles, which could potentially serve as a priori O3 profile information in TEMPO retrievals, from near-real-time (NRT) data assimilation model products (NASA Global Modeling and Assimilation Office (GMAO) Goddard Earth Observing System (GEOS-5) Forward Processing (FP) and Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA2)) and full chemical transport model (CTM), GEOS-Chem, simulations. The TB-Clim dataset and model products are evaluated with surface (0-2 km) and tropospheric (0-10 km) TOLNet observations to demonstrate the accuracy of the suggested a priori dataset and information which could potentially be used in TEMPO O3 algorithms. This study also presents the impact of individual a priori profile sources on the accuracy of theoretical TEMPO O3 retrievals in the troposphere and at the surface. Preliminary results indicate that while the TB-Clim climatological dataset can replicate seasonally-averaged tropospheric O3 profiles observed by TOLNet, model-simulated profiles from a full CTM (GEOS-Chem is used as a proxy for CTM O3 predictions) resulted in more accurate tropospheric and surface-level O3 retrievals from TEMPO when compared to hourly (diurnal cycle evaluation) and daily-averaged (daily variability evaluation) TOLNet observations. Furthermore, it was determined that when large daily-averaged surface O3 mixing ratios are observed (65 ppb), which are important for air quality purposes, TEMPO retrieval values at the surface display higher correlations and less bias when applying CTM a priori profile information

  12. Inversion with a priori information: a step toward consistent and integrated interpretations of reservoirs

    SciTech Connect

    Brac, J.; Dequirez, P.Y.; Jacques, C.; Lailly, P.; Richard, V.; Van Nhieu, D.T.

    1988-08-01

    The authors have designed a method to provide the interpreter with an acoustical impedance distribution such that (1) it matches the well logs exactly, (2) it fulfills the geological information (depositional environment, geometry of the faults, etc) specified by the interpreter, and (3) it best fits the associated synthetic seismic section with the stacked seismic section. Such an approach is especially suitable for interpolating or extrapolating well logs derived from seismic data and should ensure the consistency of the interpretations.

  13. Testing the hypothesis of neurodegeneracy in respiratory network function with a priori transected arterially perfused brain stem preparation of rat

    PubMed Central

    Jones, Sarah E.

    2016-01-01

    Degeneracy of respiratory network function would imply that anatomically discrete aspects of the brain stem are capable of producing respiratory rhythm. To test this theory we a priori transected brain stem preparations before reperfusion and reoxygenation at 4 rostrocaudal levels: 1.5 mm caudal to obex (n = 5), at obex (n = 5), and 1.5 (n = 7) and 3 mm (n = 6) rostral to obex. The respiratory activity of these preparations was assessed via recordings of phrenic and vagal nerves and lumbar spinal expiratory motor output. Preparations with a priori transection at level of the caudal brain stem did not produce stable rhythmic respiratory bursting, even when the arterial chemoreceptors were stimulated with sodium cyanide (NaCN). Reperfusion of brain stems that preserved the pre-Bötzinger complex (pre-BötC) showed spontaneous and sustained rhythmic respiratory bursting at low phrenic nerve activity (PNA) amplitude that occurred simultaneously in all respiratory motor outputs. We refer to this rhythm as the pre-BötC burstlet-type rhythm. Conserving circuitry up to the pontomedullary junction consistently produced robust high-amplitude PNA at lower burst rates, whereas sequential motor patterning across the respiratory motor outputs remained absent. Some of the rostrally transected preparations expressed both burstlet-type and regular PNA amplitude rhythms. Further analysis showed that the burstlet-type rhythm and high-amplitude PNA had 1:2 quantal relation, with burstlets appearing to trigger high-amplitude bursts. We conclude that no degenerate rhythmogenic circuits are located in the caudal medulla oblongata and confirm the pre-BötC as the primary rhythmogenic kernel. The absence of sequential motor patterning in a priori transected preparations suggests that pontine circuits govern respiratory pattern formation. PMID:26888109

  14. A no a priori knowledge estimation of the impulse response for satellite image noise reduction

    NASA Astrophysics Data System (ADS)

    Benbouzid, A. B.; Taleb, N.

    2015-04-01

    Due to launching vibrations and space harsh environment, high resolution remote sensing satellite imaging systems require permanent assessment and control of image quality, which may vary between ground pre-launch measurements, after launch and over satellite lifetime. In order to mitigate noise, remove artifacts and enhance image interpretability, the Point Spread Function (PSF) of the imaging system is estimated. Image deconvolution can be performed across the characterization of the actual Modulation Transfer Function (MTF) of the imaging system. In this work we focus on adapting and applying a no reference method to characterize in orbit high resolution satellite images in terms of geometrical performance. Moreover, we use natural details contained in images as edges transitions to estimate the impulse response via the assessment of the MTF image. The obtained results are encouraging and promising.

  15. Parametric Study of Urban-Like Topographic Statistical Moments Relevant to a Priori Modelling of Bulk Aerodynamic Parameters

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaowei; Iungo, G. Valerio; Leonardi, Stefano; Anderson, William

    2017-02-01

    For a horizontally homogeneous, neutrally stratified atmospheric boundary layer (ABL), aerodynamic roughness length, z_0, is the effective elevation at which the streamwise component of mean velocity is zero. A priori prediction of z_0 based on topographic attributes remains an open line of inquiry in planetary boundary-layer research. Urban topographies - the topic of this study - exhibit spatial heterogeneities associated with variability of building height, width, and proximity with adjacent buildings; such variability renders a priori, prognostic z_0 models appealing. Here, large-eddy simulation (LES) has been used in an extensive parametric study to characterize the ABL response (and z_0) to a range of synthetic, urban-like topographies wherein statistical moments of the topography have been systematically varied. Using LES results, we determined the hierarchical influence of topographic moments relevant to setting z_0. We demonstrate that standard deviation and skewness are important, while kurtosis is negligible. This finding is reconciled with a model recently proposed by Flack and Schultz (J Fluids Eng 132:041203-1-041203-10, 2010), who demonstrate that z_0 can be modelled with standard deviation and skewness, and two empirical coefficients (one for each moment). We find that the empirical coefficient related to skewness is not constant, but exhibits a dependence on standard deviation over certain ranges. For idealized, quasi-uniform cubic topographies and for complex, fully random urban-like topographies, we demonstrate strong performance of the generalized Flack and Schultz model against contemporary roughness correlations.

  16. A priori evaluation of two-stage cluster sampling for accuracy assessment of large-area land-cover maps

    USGS Publications Warehouse

    Wickham, J.D.; Stehman, S.V.; Smith, J.H.; Wade, T.G.; Yang, L.

    2004-01-01

    Two-stage cluster sampling reduces the cost of collecting accuracy assessment reference data by constraining sample elements to fall within a limited number of geographic domains (clusters). However, because classification error is typically positively spatially correlated, within-cluster correlation may reduce the precision of the accuracy estimates. The detailed population information to quantify a priori the effect of within-cluster correlation on precision is typically unavailable. Consequently, a convenient, practical approach to evaluate the likely performance of a two-stage cluster sample is needed. We describe such an a priori evaluation protocol focusing on the spatial distribution of the sample by land-cover class across different cluster sizes and costs of different sampling options, including options not imposing clustering. This protocol also assesses the two-stage design's adequacy for estimating the precision of accuracy estimates for rare land-cover classes. We illustrate the approach using two large-area, regional accuracy assessments from the National Land-Cover Data (NLCD), and describe how the a priorievaluation was used as a decision-making tool when implementing the NLCD design.

  17. Use of a priori spectral information in the measurement of x-ray flux with filtered diode arrays

    NASA Astrophysics Data System (ADS)

    Marrs, R. E.; Widmann, K.; Brown, G. V.; Heeter, R. F.; MacLaren, S. A.; May, M. J.; Moore, A. S.; Schneider, M. B.

    2015-10-01

    Filtered x-ray diode (XRD) arrays are often used to measure x-ray spectra vs. time from spectrally continuous x-ray sources such as hohlraums. A priori models of the incident x-ray spectrum enable a more accurate unfolding of the x-ray flux as compared to the standard technique of modifying a thermal Planckian with spectral peaks or dips at the response energy of each filtered XRD channel. A model x-ray spectrum consisting of a thermal Planckian, a Gaussian at higher energy, and (in some cases) a high energy background provides an excellent fit to XRD-array measurements of x-ray emission from laser heated hohlraums. If high-resolution measurements of part of the x-ray emission spectrum are available, that information can be included in the a priori model. In cases where the x-ray emission spectrum is not Planckian, candidate x-ray spectra can be allowed or excluded by fitting them to measured XRD voltages. Examples are presented from the filtered XRD arrays, named Dante, at the National Ignition Facility and the Laboratory for Laser Energetics.

  18. Use of a priori spectral information in the measurement of x-ray flux with filtered diode arrays.

    PubMed

    Marrs, R E; Widmann, K; Brown, G V; Heeter, R F; MacLaren, S A; May, M J; Moore, A S; Schneider, M B

    2015-10-01

    Filtered x-ray diode (XRD) arrays are often used to measure x-ray spectra vs. time from spectrally continuous x-ray sources such as hohlraums. A priori models of the incident x-ray spectrum enable a more accurate unfolding of the x-ray flux as compared to the standard technique of modifying a thermal Planckian with spectral peaks or dips at the response energy of each filtered XRD channel. A model x-ray spectrum consisting of a thermal Planckian, a Gaussian at higher energy, and (in some cases) a high energy background provides an excellent fit to XRD-array measurements of x-ray emission from laser heated hohlraums. If high-resolution measurements of part of the x-ray emission spectrum are available, that information can be included in the a priori model. In cases where the x-ray emission spectrum is not Planckian, candidate x-ray spectra can be allowed or excluded by fitting them to measured XRD voltages. Examples are presented from the filtered XRD arrays, named Dante, at the National Ignition Facility and the Laboratory for Laser Energetics.

  19. A Priori and a Posteriori Dietary Patterns during Pregnancy and Gestational Weight Gain: The Generation R Study.

    PubMed

    Tielemans, Myrte J; Erler, Nicole S; Leermakers, Elisabeth T M; van den Broek, Marion; Jaddoe, Vincent W V; Steegers, Eric A P; Kiefte-de Jong, Jessica C; Franco, Oscar H

    2015-11-12

    Abnormal gestational weight gain (GWG) is associated with adverse pregnancy outcomes. We examined whether dietary patterns are associated with GWG. Participants included 3374 pregnant women from a population-based cohort in the Netherlands. Dietary intake during pregnancy was assessed with food-frequency questionnaires. Three a posteriori-derived dietary patterns were identified using principal component analysis: a "Vegetable, oil and fish", a "Nuts, high-fiber cereals and soy", and a "Margarine, sugar and snacks" pattern. The a priori-defined dietary pattern was based on national dietary recommendations. Weight was repeatedly measured around 13, 20 and 30 weeks of pregnancy; pre-pregnancy and maximum weight were self-reported. Normal weight women with high adherence to the "Vegetable, oil and fish" pattern had higher early-pregnancy GWG than those with low adherence (43 g/week (95% CI 16; 69) for highest vs. lowest quartile (Q)). Adherence to the "Margarine, sugar and snacks" pattern was associated with a higher prevalence of excessive GWG (OR 1.45 (95% CI 1.06; 1.99) Q4 vs. Q1). Normal weight women with higher scores on the "Nuts, high-fiber cereals and soy" pattern had more moderate GWG than women with lower scores (-0.01 (95% CI -0.02; -0.00) per SD). The a priori-defined pattern was not associated with GWG. To conclude, specific dietary patterns may play a role in early pregnancy but are not consistently associated with GWG.

  20. A Priori Analysis of a Compressible Flamelet Model using RANS Data for a Dual-Mode Scramjet Combustor

    NASA Technical Reports Server (NTRS)

    Quinlan, Jesse R.; Drozda, Tomasz G.; McDaniel, James C.; Lacaze, Guilhem; Oefelein, Joseph

    2015-01-01

    In an effort to make large eddy simulation of hydrocarbon-fueled scramjet combustors more computationally accessible using realistic chemical reaction mechanisms, a compressible flamelet/progress variable (FPV) model was proposed that extends current FPV model formulations to high-speed, compressible flows. Development of this model relied on observations garnered from an a priori analysis of the Reynolds-Averaged Navier-Stokes (RANS) data obtained for the Hypersonic International Flight Research and Experimentation (HI-FiRE) dual-mode scramjet combustor. The RANS data were obtained using a reduced chemical mechanism for the combustion of a JP-7 surrogate and were validated using avail- able experimental data. These RANS data were then post-processed to obtain, in an a priori fashion, the scalar fields corresponding to an FPV-based modeling approach. In the current work, in addition to the proposed compressible flamelet model, a standard incompressible FPV model was also considered. Several candidate progress variables were investigated for their ability to recover static temperature and major and minor product species. The effects of pressure and temperature on the tabulated progress variable source term were characterized, and model coupling terms embedded in the Reynolds- averaged Navier-Stokes equations were studied. Finally, results for the novel compressible flamelet/progress variable model were presented to demonstrate the improvement attained by modeling the effects of pressure and flamelet boundary conditions on the combustion.

  1. A Priori and a Posteriori Dietary Patterns during Pregnancy and Gestational Weight Gain: The Generation R Study

    PubMed Central

    Tielemans, Myrte J.; Erler, Nicole S.; Leermakers, Elisabeth T. M.; van den Broek, Marion; Jaddoe, Vincent W. V.; Steegers, Eric A. P.; Kiefte-de Jong, Jessica C.; Franco, Oscar H.

    2015-01-01

    Abnormal gestational weight gain (GWG) is associated with adverse pregnancy outcomes. We examined whether dietary patterns are associated with GWG. Participants included 3374 pregnant women from a population-based cohort in the Netherlands. Dietary intake during pregnancy was assessed with food-frequency questionnaires. Three a posteriori-derived dietary patterns were identified using principal component analysis: a “Vegetable, oil and fish”, a “Nuts, high-fiber cereals and soy”, and a “Margarine, sugar and snacks” pattern. The a priori-defined dietary pattern was based on national dietary recommendations. Weight was repeatedly measured around 13, 20 and 30 weeks of pregnancy; pre-pregnancy and maximum weight were self-reported. Normal weight women with high adherence to the “Vegetable, oil and fish” pattern had higher early-pregnancy GWG than those with low adherence (43 g/week (95% CI 16; 69) for highest vs. lowest quartile (Q)). Adherence to the “Margarine, sugar and snacks” pattern was associated with a higher prevalence of excessive GWG (OR 1.45 (95% CI 1.06; 1.99) Q4 vs. Q1). Normal weight women with higher scores on the “Nuts, high-fiber cereals and soy” pattern had more moderate GWG than women with lower scores (−0.01 (95% CI −0.02; −0.00) per SD). The a priori-defined pattern was not associated with GWG. To conclude, specific dietary patterns may play a role in early pregnancy but are not consistently associated with GWG. PMID:26569303

  2. Estimating a-priori kinematic wave model parameters based on regionalization for flash flood forecasting in the Conterminous United States

    NASA Astrophysics Data System (ADS)

    Vergara, Humberto; Kirstetter, Pierre-Emmanuel; Gourley, Jonathan J.; Flamig, Zachary L.; Hong, Yang; Arthur, Ami; Kolar, Randall

    2016-10-01

    This study presents a methodology for the estimation of a-priori parameters of the widely used kinematic wave approximation to the unsteady, 1-D Saint-Venant equations for hydrologic flow routing. The approach is based on a multi-dimensional statistical modeling of the macro scale spatial variability of rating curve parameters using a set of geophysical factors including geomorphology, hydro-climatology and land cover/land use over the Conterminous United States. The main goal of this study was to enable prediction at ungauged locations through regionalization of model parameters. The results highlight the importance of regional and local geophysical factors in uniquely defining characteristics of each stream reach conforming to physical theory of fluvial hydraulics. The application of the estimates is demonstrated through a hydrologic modeling evaluation of a deterministic forecasting system performed on 1672 gauged basins and 47,563 events extracted from a 10-year simulation. Considering the mean concentration time of the basins of the study and the target application on flash flood forecasting, the skill of the flow routing simulations is significantly high for peakflow and timing of peakflow estimation, and shows consistency as indicated by the large sample verification. The resulting a-priori estimates can be used in any hydrologic model that employs the kinematic wave model for flow routing. Furthermore, probabilistic estimates of kinematic wave parameters are enabled based on uncertainty information that is generated during the multi-dimensional statistical modeling. More importantly, the methodology presented in this study enables the estimation of the kinematic wave model parameters anywhere over the globe, thus allowing flood modeling in ungauged basins at regional to global scales.

  3. Regional Travel-Time Uncertainty and Seismic Location Improvement Using a Three- Dimensional a priori Velocity Model

    NASA Astrophysics Data System (ADS)

    Flanagan, M. P.; Myers, S. C.; Koper, K. D.

    2006-12-01

    We demonstrate our ability to improve regional travel-time prediction and seismic event location accuracy using ana priori, three-dimensional velocity model of Western Eurasia and North Africa (WENA1.0). Travel- time residuals are assessed relative to the iasp91 model for approximately 6,000 Pg, Pn, and P arrivals, from seismic events having 2sigma epicenter accuracy between 1 km and 25 km (GT1 and GT25, respectively), recorded at 39 stations throughout the model region. Ray paths range in length between 0 and 40 degrees epicentral distance (local, regional, and near teleseismic) providing depth sounding that spans the crust and upper mantle. The dataset also provides representative geographic sampling across Eurasia and North Africa including aseismic areas. The WENA1.0 model markedly improves travel-time predictions for most stations with an average variance reduction of 29% for all ray paths from the GT25 events; when we consider GT5 and better events alone the variance reduction is 49%. For location tests we use 196 geographically distributed GT5 and better events. In 134 cases (68% of the events), locations are improved, and average mislocation is reduced from 24.9 km to 17.7 km. We develop a travel time uncertainty model that is used to calculate location coverage ellipses. The coverage ellipses for WENA1.0 are validated to be representative of epicenter error and are smaller than those for iasp91 by 37%. We conclude that a priori, models are directly applicable where data coverage limits tomographic and empirical approaches, and the development of the uncertainty model enables merging of a priori, and data-driven approaches using Bayesian techniques. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48, Contribution UCRL- JRNL-220179.

  4. Layering ratios: a systematic approach to the inversion of surface wave data in the absence of a priori information

    NASA Astrophysics Data System (ADS)

    Cox, Brady R.; Teague, David P.

    2016-10-01

    Surface wave methods provide a cost effective means of developing shear wave velocity (Vs) profiles for applications such as dynamic site characterization and seismic site response analyses. However, the inverse problem involved in obtaining a realistic layered earth model from surface wave dispersion data is inherently ill-posed, non-linear and mix-determined, without a unique solution. When available, a priori information such as geotechnical boreholes or geologic well logs should be used to aid in constraining site-specific inversion parameters. Unfortunately, a priori information is often unavailable, particularly at significant depths, and a `blind analysis' must be performed. In these situations, the analyst must decide on an appropriate number of layers and ranges for their corresponding inversion parameters (i.e. trial number of layers and ranges in their respective thicknesses, shear wave velocities, compression wave velocities and mass densities). Selection of these parameters has been shown to significantly impact the results of an inversion. This paper presents a method for conducting multiple inversions utilizing systematically varied inversion layering parametrizations in order to identify and encompass the most reasonable layered earth models for a site. Each parametrization is defined by a unique layering ratio, which represents a multiplier that systemically increases the potential thickness of each layer in the inversion parametrization based on the potential thickness of the layer directly above it. The layering ratio method is demonstrated at two sites associated with the InterPacific Project, wherein it is shown to significantly aid in selecting reasonable Vs profiles that are close representations of the subsurface. While the goal of the layering ratio inversion methodology is not necessarily to find the `optimal' or `best' Vs profile for a site, it may be successful at doing so for certain sites/datasets. However, the primary reason for using

  5. Phillips-Tikhonov regularization with a priori information for neutron emission tomographic reconstruction on Joint European Torus

    SciTech Connect

    Bielecki, J.; Scholz, M.; Drozdowicz, K.; Giacomelli, L.; Kiptily, V.; Kempenaars, M.; Conroy, S.; Craciunescu, T.; Collaboration: EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB

    2015-09-15

    A method of tomographic reconstruction of the neutron emissivity in the poloidal cross section of the Joint European Torus (JET, Culham, UK) tokamak was developed. Due to very limited data set (two projection angles, 19 lines of sight only) provided by the neutron emission profile monitor (KN3 neutron camera), the reconstruction is an ill-posed inverse problem. The aim of this work consists in making a contribution to the development of reliable plasma tomography reconstruction methods that could be routinely used at JET tokamak. The proposed method is based on Phillips-Tikhonov regularization and incorporates a priori knowledge of the shape of normalized neutron emissivity profile. For the purpose of the optimal selection of the regularization parameters, the shape of normalized neutron emissivity profile is approximated by the shape of normalized electron density profile measured by LIDAR or high resolution Thomson scattering JET diagnostics. In contrast with some previously developed methods of ill-posed plasma tomography reconstruction problem, the developed algorithms do not include any post-processing of the obtained solution and the physical constrains on the solution are imposed during the regularization process. The accuracy of the method is at first evaluated by several tests with synthetic data based on various plasma neutron emissivity models (phantoms). Then, the method is applied to the neutron emissivity reconstruction for JET D plasma discharge #85100. It is demonstrated that this method shows good performance and reliability and it can be routinely used for plasma neutron emissivity reconstruction on JET.

  6. A Novel Principal Component Analysis-Based Acceleration Scheme for LES-ODT: An A Priori Study

    NASA Astrophysics Data System (ADS)

    Echekki, Tarek; Mirgolbabaei, Hessan

    2012-11-01

    A parameterization of the composition space based on principal component analysis (PCA) is proposed to represent the transport equations with the one-dimensional turbulence (ODT) solutions of a hybrid large-eddy simulation (LES) and ODT scheme. An a priori validation of the proposed approach is implemented based on stand-alone ODT solutions of the Sandia Flame F flame, which is characterized by different regimes of combustion starting with pilot stabilization, to extinction and reignition and self-stabilized combustion. The PCA analysis is carried out with a full set of the thermo-chemical scalars' vector as well as a subset of this vector. The subset is made up primarily of major species and temperature. The results show that the different regimes are reproduced using only three principal components for the thermo-chemical scalars based on the full and a subset of the thermo-chemical scalars' vector. Reproduction of the source term of the principal component represents a greater challenge. It is found that using the subset of the thermo-chemical scalars' vector both minor species and the first three principal components source terms are reasonably well predicted.

  7. Phillips-Tikhonov regularization with a priori information for neutron emission tomographic reconstruction on Joint European Torus.

    PubMed

    Bielecki, J; Giacomelli, L; Kiptily, V; Scholz, M; Drozdowicz, K; Conroy, S; Craciunescu, T; Kempenaars, M

    2015-09-01

    A method of tomographic reconstruction of the neutron emissivity in the poloidal cross section of the Joint European Torus (JET, Culham, UK) tokamak was developed. Due to very limited data set (two projection angles, 19 lines of sight only) provided by the neutron emission profile monitor (KN3 neutron camera), the reconstruction is an ill-posed inverse problem. The aim of this work consists in making a contribution to the development of reliable plasma tomography reconstruction methods that could be routinely used at JET tokamak. The proposed method is based on Phillips-Tikhonov regularization and incorporates a priori knowledge of the shape of normalized neutron emissivity profile. For the purpose of the optimal selection of the regularization parameters, the shape of normalized neutron emissivity profile is approximated by the shape of normalized electron density profile measured by LIDAR or high resolution Thomson scattering JET diagnostics. In contrast with some previously developed methods of ill-posed plasma tomography reconstruction problem, the developed algorithms do not include any post-processing of the obtained solution and the physical constrains on the solution are imposed during the regularization process. The accuracy of the method is at first evaluated by several tests with synthetic data based on various plasma neutron emissivity models (phantoms). Then, the method is applied to the neutron emissivity reconstruction for JET D plasma discharge #85100. It is demonstrated that this method shows good performance and reliability and it can be routinely used for plasma neutron emissivity reconstruction on JET.

  8. Phillips-Tikhonov regularization with a priori information for neutron emission tomographic reconstruction on Joint European Torus

    NASA Astrophysics Data System (ADS)

    Bielecki, J.; Giacomelli, L.; Kiptily, V.; Scholz, M.; Drozdowicz, K.; Conroy, S.; Craciunescu, T.; Kempenaars, M.

    2015-09-01

    A method of tomographic reconstruction of the neutron emissivity in the poloidal cross section of the Joint European Torus (JET, Culham, UK) tokamak was developed. Due to very limited data set (two projection angles, 19 lines of sight only) provided by the neutron emission profile monitor (KN3 neutron camera), the reconstruction is an ill-posed inverse problem. The aim of this work consists in making a contribution to the development of reliable plasma tomography reconstruction methods that could be routinely used at JET tokamak. The proposed method is based on Phillips-Tikhonov regularization and incorporates a priori knowledge of the shape of normalized neutron emissivity profile. For the purpose of the optimal selection of the regularization parameters, the shape of normalized neutron emissivity profile is approximated by the shape of normalized electron density profile measured by LIDAR or high resolution Thomson scattering JET diagnostics. In contrast with some previously developed methods of ill-posed plasma tomography reconstruction problem, the developed algorithms do not include any post-processing of the obtained solution and the physical constrains on the solution are imposed during the regularization process. The accuracy of the method is at first evaluated by several tests with synthetic data based on various plasma neutron emissivity models (phantoms). Then, the method is applied to the neutron emissivity reconstruction for JET D plasma discharge #85100. It is demonstrated that this method shows good performance and reliability and it can be routinely used for plasma neutron emissivity reconstruction on JET.

  9. Enhancing the performance of model-based elastography by incorporating additional a priori information in the modulus image reconstruction process

    NASA Astrophysics Data System (ADS)

    Doyley, Marvin M.; Srinivasan, Seshadri; Dimidenko, Eugene; Soni, Nirmal; Ophir, Jonathan

    2006-01-01

    Model-based elastography is fraught with problems owing to the ill-posed nature of the inverse elasticity problem. To overcome this limitation, we have recently developed a novel inversion scheme that incorporates a priori information concerning the mechanical properties of the underlying tissue structures, and the variance incurred during displacement estimation in the modulus image reconstruction process. The information was procured by employing standard strain imaging methodology, and introduced in the reconstruction process through the generalized Tikhonov approach. In this paper, we report the results of experiments conducted on gelatin phantoms to evaluate the performance of modulus elastograms computed with the generalized Tikhonov (GTK) estimation criterion relative to those computed by employing the un-weighted least-squares estimation criterion, the weighted least-squares estimation criterion and the standard Tikhonov method (i.e., the generalized Tikhonov method with no modulus prior). The results indicate that modulus elastograms computed with the generalized Tikhonov approach had superior elastographic contrast discrimination and contrast recovery. In addition, image reconstruction was more resilient to structural decorrelation noise when additional constraints were imposed on the reconstruction process through the GTK method.

  10. A priori testing of subgrid-scale models for the velocity-pressure and vorticity-velocity formulations

    NASA Technical Reports Server (NTRS)

    Winckelmans, G. S.; Lund, T. S.; Carati, D.; Wray, A. A.

    1996-01-01

    Subgrid-scale models for Large Eddy Simulation (LES) in both the velocity-pressure and the vorticity-velocity formulations were evaluated and compared in a priori tests using spectral Direct Numerical Simulation (DNS) databases of isotropic turbulence: 128(exp 3) DNS of forced turbulence (Re(sub(lambda))=95.8) filtered, using the sharp cutoff filter, to both 32(exp 3) and 16(exp 3) synthetic LES fields; 512(exp 3) DNS of decaying turbulence (Re(sub(Lambda))=63.5) filtered to both 64(exp 3) and 32(exp 3) LES fields. Gaussian and top-hat filters were also used with the 128(exp 3) database. Different LES models were evaluated for each formulation: eddy-viscosity models, hyper eddy-viscosity models, mixed models, and scale-similarity models. Correlations between exact versus modeled subgrid-scale quantities were measured at three levels: tensor (traceless), vector (solenoidal 'force'), and scalar (dissipation) levels, and for both cases of uniform and variable coefficient(s). Different choices for the 1/T scaling appearing in the eddy-viscosity were also evaluated. It was found that the models for the vorticity-velocity formulation produce higher correlations with the filtered DNS data than their counterpart in the velocity-pressure formulation. It was also found that the hyper eddy-viscosity model performs better than the eddy viscosity model, in both formulations.

  11. Wiener filtering of surface EMG with a priori SNR estimation toward myoelectric control for neurological injury patients.

    PubMed

    Liu, Jie; Ying, Dongwen; Zhou, Ping

    2014-12-01

    Voluntary surface electromyogram (EMG) signals from neurological injury patients are often corrupted by involuntary background interference or spikes, imposing difficulties for myoelectric control. We present a novel framework to suppress involuntary background spikes during voluntary surface EMG recordings. The framework applies a Wiener filter to restore voluntary surface EMG signals based on tracking a priori signal to noise ratio (SNR) by using the decision-directed method. Semi-synthetic surface EMG signals contaminated by different levels of involuntary background spikes were constructed from a database of surface EMG recordings in a group of spinal cord injury subjects. After the processing, the onset detection of voluntary muscle activity was significantly improved against involuntary background spikes. The magnitude of voluntary surface EMG signals can also be reliably estimated for myoelectric control purpose. Compared with the previous sample entropy analysis for suppressing involuntary background spikes, the proposed framework is characterized by quick and simple implementation, making it more suitable for application in a myoelectric control system toward neurological injury rehabilitation.

  12. Almost half of the Danish general practitioners have negative a priori attitudes towards a mandatory accreditation programme.

    PubMed

    Waldorff, Frans Boch; Nicolaisdóttir, Dagný Rós; Kousgaard, Marius Brostrøm; Reventlow, Susanne; Søndergaard, Jens; Thorsen, Thorkil; Andersen, Merethe Kirstine; Pedersen, Line Bjørnskov; Bisgaard, Louise; Hutters, Cecilie Lybeck; Bro, Flemming

    2016-09-01

    The objective of this study was to analyse Danish general practitioners' (GPs) a priori attitudes and expectations towards a nationwide mandatory accreditation programme. This study is based on a nationwide electronic survey comprising all Danish GPs (n = 3,403). A total of 1,906 (56%) GPs completed the questionnaire. In all, 861 (45%) had a negative attitude towards accreditation, whereas 429 (21%) were very positive or posi-tive. The negative attitudes towards accreditation were associated with being older, male and with working in a singlehanded practice. A regional difference was observed as well. GPs with negative expectations were more likely to agree that accreditation was a tool meant for external control (odds ratio (OR) = 1.87 (95% confidence interval (CI): 1.18-2.95)), less likely to agree that accreditation was a tool for quality improvement (OR = 0.018 (95% CI: 0.013-0.025)), more likely to agree that it would affect job satisfaction negatively (OR = 21.88 (95% CI: 16.10-29.72)), and they were generally less satisfied with their present job situation (OR = 2.51 (95% CI: 1.85-3.41)). Almost half of the GPs had negative attitudes towards accreditation. The three Research Units for General Practice in Odense, Aarhus and Copenhagen initiated and funded this study. The survey was recommended by the Danish Multipractice Committee (MPU 02-2015) and evaluated by the Danish Data Agency (2015-41-3684).

  13. 'Aussie normals': an a priori study to develop clinical chemistry reference intervals in a healthy Australian population.

    PubMed

    Koerbin, G; Cavanaugh, J A; Potter, J M; Abhayaratna, W P; West, N P; Glasgow, N; Hawkins, C; Armbruster, D; Oakman, C; Hickman, P E

    2015-02-01

    Development of reference intervals is difficult, time consuming, expensive and beyond the scope of most laboratories. The Aussie Normals study is a direct a priori study to determine reference intervals in healthy Australian adults. All volunteers completed a health and lifestyle questionnaire and exclusion was based on conditions such as pregnancy, diabetes, renal or cardiovascular disease. Up to 91 biochemical analyses were undertaken on a variety of analytical platforms using serum samples collected from 1856 volunteers. We report on our findings for 40 of these analytes and two calculated parameters performed on the Abbott ARCHITECTci8200/ci16200 analysers. Not all samples were analysed for all assays due to volume requirements or assay/instrument availability. Results with elevated interference indices and those deemed unsuitable after clinical evaluation were removed from the database. Reference intervals were partitioned based on the method of Harris and Boyd into three scenarios, combined gender, males and females and age and gender. We have performed a detailed reference interval study on a healthy Australian population considering the effects of sex, age and body mass. These reference intervals may be adapted to other manufacturer's analytical methods using method transference.

  14. Randomized clinical trials in orthodontics are rarely registered a priori and often published late or not at all

    PubMed Central

    Antonoglou, Georgios N.; Sándor, George K.; Eliades, Theodore

    2017-01-01

    A priori registration of randomized clinical trials is crucial to the transparency and credibility of their findings. Aim of this study was to assess the frequency with which registered and completed randomized trials in orthodontics are published. We searched ClinicalTrials.gov and ISRCTN for registered randomized clinical trials in orthodontics that had been completed up to January 2017 and judged the publication status and date of registered trials using a systematic protocol. Statistical analysis included descriptive statistics, chi-square or Fisher exact tests, and Kaplan-Meier survival estimates. From the 266 orthodontic trials registered up to January 2017, 80 trials had been completed and included in the present study. Among these 80 included trials, the majority (76%) were registered retrospectively, while only 33 (41%) were published at the time. The median time from completion to publication was 20.1 months (interquartile range: 9.1 to 31.6 months), while survival analysis indicated that less than 10% of the trials were published after 5 years from their completion. Finally, 22 (28%) of completed trials remain unpublished even after 5 years from their completion. Publication rates of registered randomized trials in orthodontics remained low, even 5 years after their completion date. PMID:28777820

  15. Randomized clinical trials in orthodontics are rarely registered a priori and often published late or not at all.

    PubMed

    Papageorgiou, Spyridon N; Antonoglou, Georgios N; Sándor, George K; Eliades, Theodore

    2017-01-01

    A priori registration of randomized clinical trials is crucial to the transparency and credibility of their findings. Aim of this study was to assess the frequency with which registered and completed randomized trials in orthodontics are published. We searched ClinicalTrials.gov and ISRCTN for registered randomized clinical trials in orthodontics that had been completed up to January 2017 and judged the publication status and date of registered trials using a systematic protocol. Statistical analysis included descriptive statistics, chi-square or Fisher exact tests, and Kaplan-Meier survival estimates. From the 266 orthodontic trials registered up to January 2017, 80 trials had been completed and included in the present study. Among these 80 included trials, the majority (76%) were registered retrospectively, while only 33 (41%) were published at the time. The median time from completion to publication was 20.1 months (interquartile range: 9.1 to 31.6 months), while survival analysis indicated that less than 10% of the trials were published after 5 years from their completion. Finally, 22 (28%) of completed trials remain unpublished even after 5 years from their completion. Publication rates of registered randomized trials in orthodontics remained low, even 5 years after their completion date.

  16. A Computationally Efficient, Exploratory Approach to Brain Connectivity Incorporating False Discovery Rate Control, A Priori Knowledge, and Group Inference

    PubMed Central

    Liu, Aiping; Li, Junning; Wang, Z. Jane; McKeown, Martin J.

    2012-01-01

    Graphical models appear well suited for inferring brain connectivity from fMRI data, as they can distinguish between direct and indirect brain connectivity. Nevertheless, biological interpretation requires not only that the multivariate time series are adequately modeled, but also that there is accurate error-control of the inferred edges. The PCfdr algorithm, which was developed by Li and Wang, was to provide a computationally efficient means to control the false discovery rate (FDR) of computed edges asymptotically. The original PCfdr algorithm was unable to accommodate a priori information about connectivity and was designed to infer connectivity from a single subject rather than a group of subjects. Here we extend the original PCfdr algorithm and propose a multisubject, error-rate-controlled brain connectivity modeling approach that allows incorporation of prior knowledge of connectivity. In simulations, we show that the two proposed extensions can still control the FDR around or below a specified threshold. When the proposed approach is applied to fMRI data in a Parkinson's disease study, we find robust group evidence of the disease-related changes, the compensatory changes, and the normalizing effect of L-dopa medication. The proposed method provides a robust, accurate, and practical method for the assessment of brain connectivity patterns from functional neuroimaging data. PMID:23251232

  17. An A Priori Hot-Tearing Indicator Applied to Die-Cast Magnesium-Rare Earth Alloys

    NASA Astrophysics Data System (ADS)

    Easton, Mark A.; Gibson, Mark A.; Zhu, Suming; Abbott, Trevor B.

    2014-07-01

    Hot-tearing susceptibility is an important consideration for alloy design. Based on a review of previous research, an a priori indicator for the prediction of an alloy's hot-tearing susceptibility is proposed in this article and is applied to a range of magnesium-rare earth (RE)-based alloys. The indicator involves taking the integral over the solid fraction/temperature curve between the temperature when feeding becomes restricted (coherency) and that when a three-dimension network of solid is formed (coalescence). The hot-tearing propensity of Mg-RE alloys is found to vary greatly depending on which RE is primarily used, due to the difference in the solidification range. Mg-Nd alloys are the most susceptible to hot tearing, followed by Mg-Ce-based alloys, while Mg-La alloys show almost no hot tearing. The proposed indicator can be well applied to hot-tearing propensity of the Mg-RE alloys. It is expected that the indicator could be used as an estimation of the relative hot-tearing propensity in other alloy systems as well.

  18. Tomographic image via background subtraction using an x-ray projection image and a priori computed tomography

    PubMed Central

    Zhang, Jin; Yi, Byongyong; Lasio, Giovanni; Suntharalingam, Mohan; Yu, Cedric

    2009-01-01

    Kilovoltage x-ray projection images (kV images for brevity) are increasingly available in image guided radiotherapy (IGRT) for patient positioning. These images are two-dimensional (2D) projections of a three-dimensional (3D) object along the x-ray beam direction. Projecting a 3D object onto a plane may lead to ambiguities in the identification of anatomical structures and to poor contrast in kV images. Therefore, the use of kV images in IGRT is mainly limited to bony landmark alignments. This work proposes a novel subtraction technique that isolates a slice of interest (SOI) from a kV image with the assistance of a priori information from a previous CT scan. The method separates structural information within a preselected SOI by suppressing contributions to the unprocessed projection from out-of-SOI-plane structures. Up to a five-fold increase in the contrast-to-noise ratios (CNRs) was observed in selected regions of the isolated SOI, when compared to the original unprocessed kV image. The tomographic image via background subtraction (TIBS) technique aims to provide a quick snapshot of the slice of interest with greatly enhanced image contrast over conventional kV x-ray projections for fast and accurate image guidance of radiation therapy. With further refinements, TIBS could, in principle, provide real-time tumor localization using gantry-mounted x-ray imaging systems without the need for implanted markers. PMID:19928074

  19. LETTER TO THE EDITOR: Essentially all Gaussian two-party quantum states are a priori nonclassical but classically correlated

    NASA Astrophysics Data System (ADS)

    Slater, Paul B.

    2000-08-01

    Duan et al (Duan L-M, Giedke G, Cirac J I and Zoller P 2000 Phys. Rev. Lett. 84 2722) and, independently, Simon (Simon R 2000 Phys. Rev. Lett. 84 2726) have recently found necessary and sufficient conditions for the separability (classical correlation) of the Gaussian two-party (continuous variable) states. Duan et al remark that their criterion is based on a `much stronger bound' on the total variance of a pair of Einstein-Podolsky-Rosen-type operators than is required simply by the uncertainty relation. Here, we seek to formalize and test this particular assertion in both classical and quantum-theoretic frameworks. We first attach to these states the classical a priori probability (Jeffreys' prior), proportional to the volume element of the Fisher information metric on the Riemannian manifold of Gaussian (quadrivariate normal) probability distributions. Then, numerical evidence indicates that more than 99% of the Gaussian two-party states do, in fact, meet the more stringent criterion for separability. We collaterally note that the prior probability assigned to the classical states, that is those having positive Glauber-Sudarshan P-representations, is less than 0.001%. We, then, seek to attach as a measure to the Gaussian two-party states the volume element of the associated (quantum-theoretic) Bures (minimal monotone) metric. Our several extensive analyses, then, persistently yield probabilities of separability and classicality that are, to very high orders of accuracy, unity and zero, respectively, so the two quite distinct (classical and quantum-theoretic) forms of analysis are rather remarkably consistent in their findings.

  20. High-resolution teleseismic tomography of upper-mantle structure using an a priori three-dimensional crustal model

    NASA Astrophysics Data System (ADS)

    Waldhauser, Felix; Lippitsch, Regina; Kissling, Edi; Ansorge, Jörg

    2002-08-01

    The effect of an a priori known 3-D crustal model in teleseismic tomography of upper-mantle structure is investigated. We developed a 3-D crustal P-wave velocity model for the greater Alpine region, encompassing the central and western Alps and the northern Apennines, to estimate the crustal contribution to teleseismic traveltimes. The model is constructed by comparative use of published information from active and passive seismic surveys. The model components are chosen to represent the present large-scale Alpine crustal structure and for their significant effect on the propagation of seismic wavefields. They are first-order structures such as the crust-mantle boundary, sedimentary basins and the high-velocity Ivrea body. Teleseismic traveltime residuals are calculated for a realistic distribution of azimuths and distances by coupling a finite-difference technique to the IASP91 traveltime tables. Residuals are produced for a synthetic upper-mantle model featuring two slab structures and the 3-D crustal model on top of it. The crustal model produces traveltime residuals in the range between -0.7 and 1.5 s that vary strongly as a function of backazimuth and epicentral distance. We find that the non-linear inversion of the synthetic residuals without correcting for the 3-D crustal structure erroneously maps the crustal anomalies into the upper mantle. Correction of the residuals for crustal structure before inversion properly recovers the synthetic slab structures placed in the upper mantle. We conclude that with the increasing amount of high-quality seismic traveltime data, correction for near-surface structure is essential for increasing resolution in tomographic images of upper-mantle structure.

  1. A priori assumptions about characters as a cause of incongruence between molecular and morphological hypotheses of primate interrelationships.

    PubMed

    Tornow, Matthew A; Skelton, Randall R

    2012-01-01

    When molecules and morphology produce incongruent hypotheses of primate interrelationships, the data are typically viewed as incompatible, and molecular hypotheses are often considered to be better indicators of phylogenetic history. However, it has been demonstrated that the choice of which taxa to include in cladistic analysis as well as assumptions about character weighting, character state transformation order, and outgroup choice all influence hypotheses of relationships and may positively influence tree topology, so that relationships between extant taxa are consistent with those found using molecular data. Thus, the source of incongruence between morphological and molecular trees may lie not in the morphological data themselves but in assumptions surrounding the ways characters evolve and their impact on cladistic analysis. In this study, we investigate the role that assumptions about character polarity and transformation order play in creating incongruence between primate phylogenies based on morphological data and those supported by multiple lines of molecular data. By releasing constraints imposed on published morphological analyses of primates from disparate clades and subjecting those data to parsimony analysis, we test the hypothesis that incongruence between morphology and molecules results from inherent flaws in morphological data. To quantify the difference between incongruent trees, we introduce a new method called branch slide distance (BSD). BSD mitigates many of the limitations attributed to other tree comparison methods, thus allowing for a more accurate measure of topological similarity. We find that releasing a priori constraints on character behavior often produces trees that are consistent with molecular trees. Case studies are presented that illustrate how congruence between molecules and unconstrained morphological data may provide insight into issues of polarity, transformation order, homology, and homoplasy.

  2. Local digital control of power electronic converters in a dc microgrid based on a-priori derivation of switching surfaces

    NASA Astrophysics Data System (ADS)

    Banerjee, Bibaswan

    In power electronic basedmicrogrids, the computational requirements needed to implement an optimized online control strategy can be prohibitive. The work presented in this dissertation proposes a generalized method of derivation of geometric manifolds in a dc microgrid that is based on the a-priori computation of the optimal reactions and trajectories for classes of events in a dc microgrid. The proposed states are the stored energies in all the energy storage elements of the dc microgrid and power flowing into them. It is anticipated that calculating a large enough set of dissimilar transient scenarios will also span many scenarios not specifically used to develop the surface. These geometric manifolds will then be used as reference surfaces in any type of controller, such as a sliding mode hysteretic controller. The presence of switched power converters in microgrids involve different control actions for different system events. The control of the switch states of the converters is essential for steady state and transient operations. A digital memory look-up based controller that uses a hysteretic sliding mode control strategy is an effective technique to generate the proper switch states for the converters. An example dcmicrogrid with three dc-dc boost converters and resistive loads is considered for this work. The geometric manifolds are successfully generated for transient events, such as step changes in the loads and the sources. The surfaces corresponding to a specific case of step change in the loads are then used as reference surfaces in an EEPROM for experimentally validating the control strategy. The required switch states corresponding to this specific transient scenario are programmed in the EEPROM as a memory table. This controls the switching of the dc-dc boost converters and drives the system states to the reference manifold. In this work, it is shown that this strategy effectively controls the system for a transient condition such as step changes

  3. A priori and a posteriori approaches for finding genes of evolutionary interest in non-model species: osmoregulatory genes in the kidney transcriptome of the desert rodent Dipodomys spectabilis (banner-tailed kangaroo rat).

    PubMed

    Marra, Nicholas J; Eo, Soo Hyung; Hale, Matthew C; Waser, Peter M; DeWoody, J Andrew

    2012-12-01

    One common goal in evolutionary biology is the identification of genes underlying adaptive traits of evolutionary interest. Recently next-generation sequencing techniques have greatly facilitated such evolutionary studies in species otherwise depauperate of genomic resources. Kangaroo rats (Dipodomys sp.) serve as exemplars of adaptation in that they inhabit extremely arid environments, yet require no drinking water because of ultra-efficient kidney function and osmoregulation. As a basis for identifying water conservation genes in kangaroo rats, we conducted a priori bioinformatics searches in model rodents (Mus musculus and Rattus norvegicus) to identify candidate genes with known or suspected osmoregulatory function. We then obtained 446,758 reads via 454 pyrosequencing to characterize genes expressed in the kidney of banner-tailed kangaroo rats (Dipodomys spectabilis). We also determined candidates a posteriori by identifying genes that were overexpressed in the kidney. The kangaroo rat sequences revealed nine different a priori candidate genes predicted from our Mus and Rattus searches, as well as 32 a posteriori candidate genes that were overexpressed in kidney. Mutations in two of these genes, Slc12a1 and Slc12a3, cause human renal diseases that result in the inability to concentrate urine. These genes are likely key determinants of physiological water conservation in desert rodents. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Exploring the Unknown

    ERIC Educational Resources Information Center

    Pallant, Amy; Pryputniewicz, Sarah; Lee, Hee-Sun

    2012-01-01

    Scientists, and science in general, move from the unknown to increasing levels of certainty. Teaching students about science means encouraging them to embrace and investigate the unknown, make reliable scientific claims, justify those claims with evidence, and evaluate the quality of the evidence. In all areas of science--and especially in…

  5. Exploring the Unknown

    ERIC Educational Resources Information Center

    Pallant, Amy; Pryputniewicz, Sarah; Lee, Hee-Sun

    2012-01-01

    Scientists, and science in general, move from the unknown to increasing levels of certainty. Teaching students about science means encouraging them to embrace and investigate the unknown, make reliable scientific claims, justify those claims with evidence, and evaluate the quality of the evidence. In all areas of science--and especially in…

  6. Insights into organogelation and its kinetics from Hansen solubility parameters. Toward a priori predictions of molecular gelation.

    PubMed

    Diehn, Kevin K; Oh, Hyuntaek; Hashemipour, Reza; Weiss, Richard G; Raghavan, Srinivasa R

    2014-04-21

    Many small molecules can self-assemble by non-covalent interactions into fibrous networks and thereby induce gelation of organic liquids. However, no capability currently exists to predict whether a molecule in a given solvent will form a gel, a low-viscosity solution (sol), or an insoluble precipitate. Gelation has been recognized as a phenomenon that reflects a balance between solubility and insolubility; however, the distinction between these regimes has not been quantified in a systematic fashion. In this work, we focus on a well-known gelator, 1,3:2,4-dibenzylidene sorbitol (DBS), and study its self-assembly in various solvents. From these data, we build a framework for DBS gelation based on Hansen solubility parameters (HSPs). While the HSPs for DBS are not known a priori, the HSPs are available for each solvent and they quantify the solvent's ability to interact via dispersion, dipole-dipole, and hydrogen bonding interactions. Using the three HSPs, we construct three-dimensional plots showing regions of solubility (S), slow gelation (SG), instant gelation (IG), and insolubility (I) for DBS in the different solvents at a given temperature and concentration. Our principal finding is that the above regions radiate out as concentric shells: i.e., a central solubility (S) sphere, followed in order by spheres corresponding to SG, IG, and I regions. The distance (R0) from the origin of the central sphere quantifies the incompatibility between DBS and a solvent-the larger this distance, the more incompatible the pair. The elastic modulus of the final gel increases with R0, while the time required for a super-saturated sol to form a gel decreases with R0. Importantly, if R0 is too small, the gels are weak, but if R0 is too large, insolubility occurs-thus, strong gels fall within an optimal window of incompatibility between the gelator and the solvent. Our approach can be used to design organogels of desired strength and gelation time by judicious choice of a

  7. A priori estimate of the quality of a data compression system based on statistical characteristics of the sensors used

    NASA Technical Reports Server (NTRS)

    Khodarev, Y. K.; Yevdokimov, V. P.; Pokras, V. M.

    1974-01-01

    Knowledge of the composition and certain statistical characteristics of the output signals of the scientific instruments on board a space vehicle allows determination of possible signal processing algorithms in the system and to evaluate the prospects for utilization of data reduction. A method is presented to estimate the compression factor of an on-board data collection and processing system with known mean activities of the sensors used and unknown mutual correlation of their output signals.

  8. Seismicity patterns along the Ecuadorian subduction zone: new constraints from earthquake location in a 3-D a priori velocity model

    NASA Astrophysics Data System (ADS)

    Font, Yvonne; Segovia, Monica; Vaca, Sandro; Theunissen, Thomas

    2013-04-01

    To improve earthquake location, we create a 3-D a priori P-wave velocity model (3-DVM) that approximates the large velocity variations of the Ecuadorian subduction system. The 3-DVM is constructed from the integration of geophysical and geological data that depend on the structural geometry and velocity properties of the crust and the upper mantle. In addition, specific station selection is carried out to compensate for the high station density on the Andean Chain. 3-D synthetic experiments are then designed to evaluate the network capacity to recover the event position using only P arrivals and the MAXI technique. Three synthetic earthquake location experiments are proposed: (1) noise-free and (2) noisy arrivals used in the 3-DVM, and (3) noise-free arrivals used in a 1-DVM. Synthetic results indicate that, under the best conditions (exact arrival data set and 3-DVM), the spatiotemporal configuration of the Ecuadorian network can accurately locate 70 per cent of events in the frontal part of the subduction zone (average azimuthal gap is 289° ± 44°). Noisy P arrivals (up to ± 0.3 s) can accurately located 50 per cent of earthquakes. Processing earthquake location within a 1-DVM almost never allows accurate hypocentre position for offshore earthquakes (15 per cent), which highlights the role of using a 3-DVM in subduction zone. For the application to real data, the seismicity distribution from the 3-D-MAXI catalogue is also compared to the determinations obtained in a 1-D-layered VM. In addition to good-quality location uncertainties, the clustering and the depth distribution confirm the 3-D-MAXI catalogue reliability. The pattern of the seismicity distribution (a 13 yr record during the inter-seismic period of the seismic cycle) is compared to the pattern of rupture zone and asperity of the Mw = 7.9 1942 and the Mw = 7.7 1958 events (the Mw = 8.8 1906 asperity patch is not defined). We observe that the nucleation of 1942, 1958 and 1906 events coincides with

  9. Improvement of Tidal Analysis Results by a Priori Rain Fall Modelling at the Vienna and Membach stations

    NASA Astrophysics Data System (ADS)

    Meurers, B.; van Camp, M.; Petermans, T.

    2005-12-01

    We investigate how far tidal analysis results can be improved when a rain fall admittance model is applied on the superconducting gravity (SG) data. For that purpose both Vienna and Membach data have been analysed with and without a priori rain fall correction. In Membach the residual drop for most events (80%) can be explained by the rain water load, while in Vienna only 50% of all events fit the model in detail. In the other cases the Newtonian effect of vertical air mass redistribution (vertical density variation without air pressure change), predominantly connected with high vertical convection activity, e.g. thunderstorms, plays an essential role: short-term atmospheric signals show up steep gravity residual decreases of a few nms-2 within 10 - 60 min, well correlated with outdoor air temperature in most cases. However, even in those cases the water load model is able to explain the dominating part of the residual drop especially during heavy rain fall. In Vienna more than 110 events have been detected over 10 years. 84% of them are associated with heavy rain starting at or up to 10 min later than the residual drop while the rest (16%) shows no or only little rainfall. The magnitude of the gravity drop depends on the total amount of rainfall accumulated during the meteorological event. Step like signals deteriorate the frequency spectrum estimates. This even holds for tidal analysis. As the drops are of physical origin, they should not be eliminated blindly but corrected using water load modeling constrained by high temporal resolution (1 min) rain data. 3D modeling of the water mass load due to a rain event is based on the following assumptions: (1) Rain water intrudes into the uppermost soil layer (close to the topography surface) and remains there at least until rain has stopped. This is justified for a period of some hours after the rainfall as evapotranspiration is not yet effective. (2) No run-off except of sealed areas or building roofs, where water can

  10. The fetal fraction of cell-free DNA in maternal plasma is not affected by a priori risk of fetal trisomy

    PubMed Central

    2013-01-01

    Objective: To determine the relationship between a priori risk for fetal trisomy and the fraction of fetal cell-free DNA (cfDNA) in maternal blood. Methods: A comparative analysis on fetal cfDNA amounts was performed in subjects stratified into a priori risk groups based on maternal age, prenatal screening results, or nuchal translucency measurement. Results: Across the highest and lowest deciles within each group, there were no significant differences in the fetal cfDNA fraction. Conclusions: These data support the concept that non-invasive prenatal test performance as determined by fetal cfDNA fraction is not predicted to be different based on patient risk classification. PMID:22913322

  11. Heavy metal and polycyclic aromatic hydrocarbon concentrations in Quercus ilex L. leaves fit an a priori subdivision in site typologies based on human management.

    PubMed

    De Nicola, Flavia; Baldantoni, Daniela; Maisto, Giulia; Alfani, Anna

    2017-05-01

    Concentrations of four heavy metals (HMs) (Cd, Cr, Fe, Pb) and four polycyclic aromatic hydrocarbons (PAHs) (fluoranthene, phenanthrene, chrysene, benzo[a]pyrene) in Quercus ilex L. leaves collected at the Campania Region (Southern Italy) in previous air biomonitoring studies were employed to (1) test the correspondence with an a priori site subdivision (remote, periurban, and urban) and (2) evaluate long temporal trends of HM (approximately 20 years) and PAH (approximately 10 years) air contaminations. Overall, Q. ilex leaf HM and PAH concentrations resulted along the gradient: remote < periurban < urban sites, reflecting the a priori subdivision based on human management. Over a long time, although a clear decrease of leaf Pb, chrysene, fluoranthene, and phenanthrene concentrations occurred at the urban sites, a high contamination level persists.

  12. [An a priori risk analysis study. Securisation of transfusion of blood product in a hospital: from the reception in the medical unit to its administration].

    PubMed

    Bertrand, E; Lévy, R; Boyeldieu, D

    2013-12-01

    Following an ABO accident after transfusion of red blood cells, an a priori risk analysis study is being performed in a hospital. The scope of this analysis covers from the reception of the blood product in the medical unit to its administration. The risk analysis enables to identify the potentially dangerous situations and the evaluation of the risks in order to propose corrective measures (precautionary or protective) and bring the system back to an acceptable risk level. The innovative concept of an a priori risk analysis in the medical field allows the extension of the analysis of this transfusion risk to other hospitals. In addition, it allows the extension of the use of this approach to other medical fields.

  13. Bonner sphere measurements of 241Am-B and 241Am-F neutron energy spectra unfolded using high-resolution a priori data.

    PubMed

    Roberts, N J; Jones, L N; Liu, Z Z; Tagziria, H; Thomas, D J

    2014-10-01

    High-resolution neutron energy spectra, covering the entire energy range of interest, for two standard radionuclide neutron sources ((241)Am-B and (241)Am-F) have been derived from Bonner sphere measurements by using high-resolution a priori data in the unfolding process. In each case, two a priori spectra were used, one from a two-stage calculation and also one from a combination of the calculated spectrum with a high-resolution measured spectrum. The unfolded spectra are compared with those published elsewhere and show significant differences from the ISO- and IAEA-recommended spectra for (241)Am-B and (241)Am-F, respectively. Values for the fluence-average energy and fluence-to-dose-equivalent conversion coefficients are presented for the new spectra, and the implications of the new spectra for the emission rates of the sources when measured by the manganese bath technique are also determined. © Crown copyright 2013.

  14. A gridded version of the US EPA inventory of methane emissions for use as a priori and reference in methane source inversions

    NASA Astrophysics Data System (ADS)

    Maasakkers, J. D.; Jacob, D. J.; Payer Sulprizio, M.; Turner, A. J.; Weitz, M.; Wirth, T. C.; Hight, C.; DeFigueiredo, M.; Desai, M.; Schmeltz, R.; Hockstad, L.; Bloom, A. A.; Bowman, K. W.

    2015-12-01

    The US EPA produces annual estimates of national anthropogenic methane emissions in the Inventory of US Greenhouse Gas Emissions and Sinks (EPA inventory). These are reported to the UN and inform national climate policy. The EPA inventory uses best available information on emitting processes (IPCC Tier 2/3 approaches). However, inversions of atmospheric observations suggest that the inventory could be too low. These inversions rely on crude bottom-up estimates as a priori because the EPA inventory is only available as national totals for most sources. Reliance on an incorrect a priori greatly limits the value of inversions for testing and improving the EPA inventory as allocation of methane emissions by source types and regions can vary greatly between different bottom-up inventories. Here we present a 0.1° × 0.1° monthly version of the EPA inventory to serve as a priori for inversions of atmospheric data and to interpret inversion results. We use a wide range of process-specific information to allocate emissions, incorporating facility-level data reported through the EPA Greenhouse Gas Reporting Program where possible. As an illustration of used gridding strategies, gridded livestock emissions are based on EPA emission data per state, USDA livestock inventories per county, and USDA weighted land cover maps for sub-county localization. Allocation of emissions from natural gas systems incorporates monthly well-level production data, EIA compressor station and processing plant databases, and information on pipelines. Our gridded EPA inventory shows large differences in spatial emission patterns compared to the EDGAR v4.2 global inventory used as a priori in previous inverse studies. Our work greatly enhances the potential of future inversions to test and improve the EPA inventory and more broadly to improve understanding of the factors controlling methane concentrations and their trends. Preliminary inversion results using GOSAT satellite data will be presented.

  15. Comparative analysis of a-priori and a-posteriori dietary patterns using state-of-the-art classification algorithms: a case/case-control study.

    PubMed

    Kastorini, Christina-Maria; Papadakis, George; Milionis, Haralampos J; Kalantzi, Kallirroi; Puddu, Paolo-Emilio; Nikolaou, Vassilios; Vemmos, Konstantinos N; Goudevenos, John A; Panagiotakos, Demosthenes B

    2013-11-01

    To compare the accuracy of a-priori and a-posteriori dietary patterns in the prediction of acute coronary syndrome (ACS) and ischemic stroke. This is actually the first study to employ state-of-the-art classification methods for this purpose. During 2009-2010, 1000 participants were enrolled; 250 consecutive patients with a first ACS and 250 controls (60±12 years, 83% males), as well as 250 consecutive patients with a first stroke and 250 controls (75±9 years, 56% males). The controls were population-based and age-sex matched to the patients. The a-priori dietary patterns were derived from the validated MedDietScore, whereas the a-posteriori ones were extracted from principal components analysis. Both approaches were modeled using six classification algorithms: multiple logistic regression (MLR), naïve Bayes, decision trees, repeated incremental pruning to produce error reduction (RIPPER), artificial neural networks and support vector machines. The classification accuracy of the resulting models was evaluated using the C-statistic. For the ACS prediction, the C-statistic varied from 0.587 (RIPPER) to 0.807 (MLR) for the a-priori analysis, while for the a-posteriori one, it fluctuated between 0.583 (RIPPER) and 0.827 (MLR). For the stroke prediction, the C-statistic varied from 0.637 (RIPPER) to 0.767 (MLR) for the a-priori analysis, and from 0.617 (decision tree) to 0.780 (MLR) for the a-posteriori. Both dietary pattern approaches achieved equivalent classification accuracy over most classification algorithms. The choice, therefore, depends on the application at hand. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Quantitation of the a priori dosimetric capabilities of spatial points in inverse planning and its significant implication in defining IMRT solution space

    NASA Astrophysics Data System (ADS)

    Shou, Z.; Yang, Y.; Cotrutz, C.; Levy, D.; Xing, Lei

    2005-04-01

    In inverse planning, the likelihood for the points in a target or sensitive structure to meet their dosimetric goals is generally heterogeneous and represents the a priori knowledge of the system once the patient and beam configuration are chosen. Because of this intrinsic heterogeneity, in some extreme cases, a region in a target may never meet the prescribed dose without seriously deteriorating the doses in other areas. Conversely, the prescription in a region may be easily met without violating the tolerance of any sensitive structure. In this work, we introduce the concept of dosimetric capability to quantify the a priori information and develop a strategy to integrate the data into the inverse planning process. An iterative algorithm is implemented to numerically compute the capability distribution on a case specific basis. A method of incorporating the capability data into inverse planning is developed by heuristically modulating the importance of the individual voxels according to the a priori capability distribution. The formalism is applied to a few specific examples to illustrate the technical details of the new inverse planning technique. Our study indicates that the dosimetric capability is a useful concept to better understand the complex inverse planning problem and an effective use of the information allows us to construct a clinically more meaningful objective function to improve IMRT dose optimization techniques. Part of this work was presented in the 14th International Conference on the Use of Computers in Radiation Therapy, Seoul, Korea, 2004.

  17. 3D photon counting integral imaging with unknown sensor positions.

    PubMed

    Xiao, Xiao; Javidi, Bahram

    2012-05-01

    Photon counting techniques have been introduced with integral imaging for three-dimensional (3D) imaging applications. The previous reports in this area assumed a priori knowledge of exact sensor positions for 3D image reconstruction, which may be difficult to satisfy in certain applications. In this paper, we extend the photon counting 3D imaging system to situations where sensor positions are unknown. To estimate sensor positions in photon counting integral imaging, scene details of photon counting images are needed for image correspondences matching. Therefore, an iterative method based on the total variation maximum a posteriori expectation maximization (MAP-EM) algorithm is used to restore photon counting images. Experimental results are presented to show the feasibility of the method. To the best of our knowledge, this is the first report on 3D photon counting integral imaging with unknown sensor positions. © 2012 Optical Society of America

  18. Multigrain indexing of unknown multiphase materials

    PubMed Central

    Wejdemann, Christian; Poulsen, Henning Friis

    2016-01-01

    A multigrain indexing algorithm for use with samples comprising an arbitrary number of known or unknown phases is presented. No a priori crystallographic knowledge is required. The algorithm applies to data acquired with a monochromatic beam and a conventional two-dimensional detector for diffraction. Initially, candidate grains are found by searching for crystallographic planes, using a Dirac comb convoluted with a box function as a filter. Next, candidate grains are validated and the unit cell is optimized. The algorithm is validated by simulations. Simulations of 500 cementite grains and ∼100 reflections per grain resulted in 99.2% of all grains being indexed correctly and 99.5% of the reflections becoming associated with the right grain. Simulations with 200 grains associated with four mineral phases and 50–700 reflections per grain resulted in 99.9% of all grains being indexed correctly and 99.9% of the reflections becoming associated with the right grain. The main limitation is in terms of overlap of diffraction spots and computing time. Potential areas of use include three-dimensional grain mapping, structural solution and refinement studies of complex samples, and studies of dilute phases. PMID:27047308

  19. Metrology with Unknown Detectors.

    PubMed

    Altorio, Matteo; Genoni, Marco G; Somma, Fabrizia; Barbieri, Marco

    2016-03-11

    The best possible precision is one of the key figures in metrology, but this is established by the exact response of the detection apparatus, which is often unknown. There exist techniques for detector characterization that have been introduced in the context of quantum technologies but apply as well for ordinary classical coherence; these techniques, though, rely on intense data processing. Here, we show that one can make use of the simpler approach of data fitting patterns in order to obtain an estimate of the Cramér-Rao bound allowed by an unknown detector, and we present applications in polarimetry. Further, we show how this formalism provides a useful calculation tool in an estimation problem involving a continuous-variable quantum state, i.e., a quantum harmonic oscillator.

  20. Minimal stochastic complexity snake-based technique adapted to an unknown noise model

    NASA Astrophysics Data System (ADS)

    Galland, Fré; Déric; Réfrégier, Philippe

    2005-09-01

    We propose a polygonal snake segmentation technique adapted to objects that can be composed of several regions with gray-level fluctuations described by a priori unknown probability laws. This approach is based on a histogram equalization and on the minimization of a criterion without parameter to be tuned by the user. We demonstrate the efficiency of this approach, which has low computational cost, on synthetic and real images perturbed by different types of optical noise.

  1. 40 CFR - Unknown Title

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Section Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS Procedures for Determining Comparability Between Candidate Methods and Reference Method...

  2. Locally optimal control under unknown dynamics with learnt cost function: application to industrial robot positioning

    NASA Astrophysics Data System (ADS)

    Guérin, Joris; Gibaru, Olivier; Thiery, Stéphane; Nyiri, Eric

    2017-01-01

    Recent methods of Reinforcement Learning have enabled to solve difficult, high dimensional, robotic tasks under unknown dynamics using iterative Linear Quadratic Gaussian control theory. These algorithms are based on building a local time-varying linear model of the dynamics from data gathered through interaction with the environment. In such tasks, the cost function is often expressed directly in terms of the state and control variables so that it can be locally quadratized to run the algorithm. If the cost is expressed in terms of other variables, a model is required to compute the cost function from the variables manipulated. We propose a method to learn the cost function directly from the data, in the same way as for the dynamics. This way, the cost function can be defined in terms of any measurable quantity and thus can be chosen more appropriately for the task to be carried out. With our method, any sensor information can be used to design the cost function. We demonstrate the efficiency of this method through simulating, with the V-REP software, the learning of a Cartesian positioning task on several industrial robots with different characteristics. The robots are controlled in joint space and no model is provided a priori. Our results are compared with another model free technique, consisting in writing the cost function as a state variable.

  3. 1. Photocopy of photograph (location of original unknown) Photographer unknown, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Photocopy of photograph (location of original unknown) Photographer unknown, ca. 1900 WEST ELEVATION - Bagatelle Plantation, East River Road (moved to Iberville Parish), Donaldsonville, Ascension Parish, LA

  4. [Fever of unknown origin].

    PubMed

    Salzberger, B; Müller-Schilling, M; Fleck, M

    2013-04-01

    Fever of unknown origin (FUO) is defined as sustained unexplained fever despite intensive diagnostic evaluation and represents a particular diagnostic challenge. It can be classified into different categories, e.g. classical, nosocomial, neutropenic and HIV-associated FUO, which is based on the patient-specific clinical and immunological situation. Infections, malignant diseases and non-infectious inflammatory diseases have to be considered as the most important causes of FUO; however, no definitive diagnosis can be established in a substantial number of FUO patients despite an extensive diagnostic work-up. The present review focuses on the important diagnostic aspects as well as therapeutic options in FUO patients.

  5. Fever of unknown origin.

    PubMed

    Miller, M L; Szer, I; Yogev, R; Bernstein, B

    1995-10-01

    The causes of fever in a child can vary from minor brief illnesses to life-threatening infectious, malignant, or autoimmune diseases. The physician often has to evaluate children with fevers of as yet undiagnosed cause lasting fewer than 2 weeks, in whom it is important to determine whether localizing findings are present. Fever without localizing signs and fevers complicating chronic disease and resulting from specific localized infection are considered in the sections concerning infectious causes, immunodeficiency diseases, and rheumatic diseases. The diagnostic and therapeutic approaches to the child with both prolonged fever and fever of unknown origin are then discussed, with emphasis on rheumatic diseases.

  6. Prediction of extinction and reignition in nonpremixed turbulent flames using a flamelet/progress variable model. 1. A priori study and presumed PDF closure

    SciTech Connect

    Ihme, Matthias; Pitsch, Heinz

    2008-10-15

    Previously conducted studies of the flamelet/progress variable model for the prediction of nonpremixed turbulent combustion processes identified two areas for model improvements: the modeling of the presumed probability density function (PDF) for the reaction progress parameter and the consideration of unsteady effects [Ihme et al., Proc. Combust. Inst. 30 (2005) 793]. These effects are of particular importance during local flame extinction and subsequent reignition. Here, the models for the presumed PDFs for conserved and reactive scalars are re-examined and a statistically most likely distribution (SMLD) is employed and tested in a priori studies using direct numerical simulation (DNS) data and experimental results from the Sandia flame series. In the first part of the paper, the SMLD model is employed for a reactive scalar distribution. Modeling aspects of the a priori PDF, accounting for the bias in composition space, are discussed. The convergence of the SMLD with increasing number of enforced moments is demonstrated. It is concluded that information about more than two moments is beneficial to accurately represent the reactive scalar distribution in turbulent flames with strong extinction and reignition. In addition to the reactive scalar analysis, the potential of the SMLD for the representation of conserved scalar distributions is also analyzed. In the a priori study using DNS data it is found that the conventionally employed beta distribution provides a better representation for the scalar distribution. This is attributed to the fact that the beta-PDF implicitly enforces higher moment information that is in excellent agreement with the DNS data. However, the SMLD outperforms the beta distribution in free shear flow applications, which are typically characterized by strongly skewed scalar distributions, in the case where higher moment information can be enforced. (author)

  7. A priori fully populated covariance matrices in least-squares adjustment—case study: GPS relative positioning

    NASA Astrophysics Data System (ADS)

    Kermarrec, Gaël; Schön, Steffen

    2017-05-01

    In this contribution, using the example of the Mátern covariance matrices, we study systematically the effect of apriori fully populated variance covariance matrices (VCM) in the Gauss-Markov model, by varying both the smoothness and the correlation length of the covariance function. Based on simulations where we consider a GPS relative positioning scenario with double differences, the true VCM is exactly known. Thus, an accurate study of parameters deviations with respect to the correlation structure is possible. By means of the mean-square error difference of the estimates obtained with the correct and the assumed VCM, the loss of efficiency when the correlation structure is missspecified is considered. The bias of the variance of unit weight is moreover analysed. By acting independently on the correlation length, the smoothness, the batch length, the noise level, or the design matrix, simulations allow to draw conclusions on the influence of these different factors on the least-squares results. Thanks to an adapted version of the Kermarrec-Schön model, fully populated VCM for GPS phase observations are computed where different correlation factors are resumed in a global covariance model with an elevation dependent weighting. Based on the data of the EPN network, two studies for different baseline lengths validate the conclusions of the simulations on the influence of the Mátern covariance parameters. A precise insight into the impact of apriori correlation structures when the VCM is entirely unknown highlights that both the correlation length and the smoothness defined in the Mátern model are important to get a lower loss of efficiency as well as a better estimation of the variance of unit weight. Consecutively, correlations, if present, should not be neglected for accurate test statistics. Therefore, a proposal is made to determine a mean value of the correlation structure based on a rough estimation of the Mátern parameters via maximum likelihood

  8. A priori fully populated covariance matrices in least-squares adjustment—case study: GPS relative positioning

    NASA Astrophysics Data System (ADS)

    Kermarrec, Gaël; Schön, Steffen

    2016-12-01

    In this contribution, using the example of the Mátern covariance matrices, we study systematically the effect of apriori fully populated variance covariance matrices (VCM) in the Gauss-Markov model, by varying both the smoothness and the correlation length of the covariance function. Based on simulations where we consider a GPS relative positioning scenario with double differences, the true VCM is exactly known. Thus, an accurate study of parameters deviations with respect to the correlation structure is possible. By means of the mean-square error difference of the estimates obtained with the correct and the assumed VCM, the loss of efficiency when the correlation structure is missspecified is considered. The bias of the variance of unit weight is moreover analysed. By acting independently on the correlation length, the smoothness, the batch length, the noise level, or the design matrix, simulations allow to draw conclusions on the influence of these different factors on the least-squares results. Thanks to an adapted version of the Kermarrec-Schön model, fully populated VCM for GPS phase observations are computed where different correlation factors are resumed in a global covariance model with an elevation dependent weighting. Based on the data of the EPN network, two studies for different baseline lengths validate the conclusions of the simulations on the influence of the Mátern covariance parameters. A precise insight into the impact of apriori correlation structures when the VCM is entirely unknown highlights that both the correlation length and the smoothness defined in the Mátern model are important to get a lower loss of efficiency as well as a better estimation of the variance of unit weight. Consecutively, correlations, if present, should not be neglected for accurate test statistics. Therefore, a proposal is made to determine a mean value of the correlation structure based on a rough estimation of the Mátern parameters via maximum likelihood

  9. [Diagnosis of fever of unknown origin: use of Bayes theorem].

    PubMed

    Campanella, N; Pergolini, M; Daher, W; Moraca, A; Borgognoni, C; Morosini, P

    1999-01-01

    Sophisticated tests and time are needed to establish the diagnosis of fever of unknown origin (FUO). Bayes theorem can guide the clinician to early probabilistic diagnosis. The authors had estimated the a priori probabilities in a previous study yet. In this paper the diagnostic probabilities of four clinical signs (arthralgias, myalgias, splenomegaly, multiple micro-lymphoadenopathies) and the probabilities of abnormalities of some routine laboratory tests (neutrophils count, lymphocytes count, platelets count, hemoglobin, lactic-dehydrogenase, C3 and C4 complement subunits and fibrinogen plasma concentrations, erythrocyte sedimentation rate) and of the positive bacterial cultures, were estimated in the main groups of FUO disease (indefinite, aspecific bacteria infections, non-bacterial or specific bacteria infections, neoplasias, connective tissue diseases, miscellaneous group). The data suggest that the a priori probability is not affected by the clinical signs. Arthralgias increase the probability of connective tissue diseases. Normal erythrocyte sedimentation rate and plasma fibrinogen concentrations increase the probability of paraneoplastic and indefinite fever. Thrombocytosis increases the probability of paraneoplastic fever. Over 1200 U/l serum lactic-dehydrogenase serum concentrations guide to non-bacterial or specific bacteria infectious diseases and to malignancies. Neutrophilia decreases the probability of indefinite diagnosis, even though it is not specific. The heterogeneity of the miscellaneous group makes the interpretations of the data very hard.

  10. Fever of unknown origin.

    PubMed

    Mulders-Manders, Catharina; Simon, Anna; Bleeker-Rovers, Chantal

    2015-06-01

    More than 50 years after the first definition of fever of unknown origin (FUO), it still remains a diagnostic challenge. Evaluation starts with the identification of potential diagnostic clues (PDCs), which should guide further investigations. In the absence of PDCs a standardised diagnostic protocol should be followed with PET-CT as the imaging technique of first choice. Even with a standardised protocol, in a large proportion of patients from western countries the cause for FUO cannot be identified. The treatment of FUO is guided by the final diagnosis, but when no cause is found, antipyretic drugs can be prescribed. Corticosteroids should be avoided in the absence of a diagnosis, especially at an early stage. The prognosis of FUO is determined by the underlying cause. The majority of patients with unexplained FUO will eventually show spontaneous remission of fever. We describe the definition, diagnostic workup, causes and treatment of FUO. © Royal College of Physicians 2015. All rights reserved.

  11. Sedna - Artist Unknown.

    PubMed

    Wentz, Margaret R

    2016-05-01

    Recognizing the contribution art has had in the Mayo Clinic environment since the original Mayo Clinic Building was finished in 1914, Mayo Clinic Proceedings features some of the numerous works of art displayed throughout the buildings and grounds on Mayo Clinic campuses as interpreted by the author.

  12. Combined use of a priori data for fast system self-calibration of a non-rigid multi-camera fringe projection system

    NASA Astrophysics Data System (ADS)

    Stavroulakis, Petros I.; Chen, Shuxiao; Sims-Waterhouse, Danny; Piano, Samanta; Southon, Nicholas; Bointon, Patrick; Leach, Richard

    2017-06-01

    In non-rigid fringe projection 3D measurement systems, where either the camera or projector setup can change significantly between measurements or the object needs to be tracked, self-calibration has to be carried out frequently to keep the measurements accurate1. In fringe projection systems, it is common to use methods developed initially for photogrammetry for the calibration of the camera(s) in the system in terms of extrinsic and intrinsic parameters. To calibrate the projector(s) an extra correspondence between a pre-calibrated camera and an image created by the projector is performed. These recalibration steps are usually time consuming and involve the measurement of calibrated patterns on planes, before the actual object can continue to be measured after a motion of a camera or projector has been introduced in the setup and hence do not facilitate fast 3D measurement of objects when frequent experimental setup changes are necessary. By employing and combining a priori information via inverse rendering, on-board sensors, deep learning and leveraging a graphics processor unit (GPU), we assess a fine camera pose estimation method which is based on optimising the rendering of a model of a scene and the object to match the view from the camera. We find that the success of this calibration pipeline can be greatly improved by using adequate a priori information from the aforementioned sources.

  13. A simulation study of the variability of indocyanine green kinetics and using structural a priori information in dynamic contrast enhanced diffuse optical tomography (DCE-DOT)

    NASA Astrophysics Data System (ADS)

    Burcin Unlu, Mehmet; Birgul, Ozlem; Gulsen, Gultekin

    2008-06-01

    We investigated (1) the variability of indocyanine green kinetics (ICG) between different cases in the existence of random noise, changing the size of the imaging region, the location and the size of the inclusion, (2) the use of structural a priori information to reduce the variability. We performed two-dimensional simulation studies for this purpose. In the simulations, we used a two-compartmental model to describe the ICG transport and obtained pharmacokinetic parameters. The transfer constant and the rate constant showed a wide variation, i.e. 60% and 95%, respectively, when random Gaussian noise with a standard deviation of 1% in amplitude and 0.4° in phase was added to data. Moreover, recovered peak ICG concentration and time to reach the peak concentration was different within different cases. When structural a priori information was used in the reconstructions, the variations in the transfer and the rate constant were reduced to 29%, 15%, respectively. As a result, although the recovered peak concentration was still case dependent, the variability of the shape of the kinetic curve was reduced.

  14. Model-based waveform design for optimal detection: A multi-objective approach to dealing with incomplete a priori knowledge.

    PubMed

    Hamschin, Brandon M; Loughlin, Patrick J

    2015-11-01

    This work considers the design of optimal, energy-constrained transmit signals for active sensing for the case when the designer has incomplete or uncertain knowledge of the target and/or environment. The mathematical formulation is that of a multi-objective optimization problem, wherein one can incorporate a plurality of potential targets, interference, or clutter models and in doing so take advantage of the wide range of results in the literature related to modeling each. It is shown, via simulation, that when the objective function of the optimization problem is chosen to maximize the minimum (i.e., maxmin) probability of detection among all possible model combinations, the optimal waveforms obtained are advantageous. The advantage results because the maxmin waveforms judiciously allocate energy to spectral regions where each of the target models respond strongly and each of the environmental models affect minimal detection performance degradation. In particular, improved detection performance is shown compared to linear frequency modulated transmit signals and compared to signals designed with the wrong target spectrum assumed. Additionally, it is shown that the maxmin design yields performance comparable to an optimal design matched to the correct target/environmental model. Finally, it is proven that the maxmin problem formulation is convex.

  15. Fever of unknown origin.

    PubMed

    Bleeker-Rovers, Chantal P; van der Meer, Jos W M; Oyen, Wim J G

    2009-03-01

    Fever of unknown origin (FUO) often is defined as a fever greater than 38.3 degrees C on several occasions during at least 3 weeks with uncertain diagnosis after a number of obligatory tests. In general, infection accounts for approximately one-fourth of cases of FUO, followed by neoplasm and noninfectious inflammatory diseases. No diagnosis is reached in up to 50% of cases. Scintigraphic methods, such as (67)Ga-citrate, labeled leukocytes, and (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET), are often used in the diagnosis of FUO. In FUO, FDG-PET appears to be of great advantage because malignancy, inflammation, and infection can be detected. FDG-PET does not seem to contribute to a final diagnosis in patients with normal erythrocyte sedimentation rate and C-reactive protein. Image fusion combining PET and computed tomography facilitates anatomical localization of increased FDG uptake and better guiding for further diagnostic tests to achieve a final diagnosis. In conclusion, the body of evidence on the utility of FDG-PET in patients with FUO is growing and FDG-PET will probably become the preferred diagnostic procedure, especially when a definite diagnosis cannot easily be achieved. Because of favorable characteristics of FDG-PET, conventional scintigraphic techniques may be replaced by FDG-PET in institutions in which PET is available.

  16. 7. Photocopy of painting (Source unknown, Date unknown) EXTERIOR SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Photocopy of painting (Source unknown, Date unknown) EXTERIOR SOUTH FRONT VIEW OF MISSION AND CONVENTO AFTER 1913 - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

  17. 66. Buckwheat Launder, date unknown Historic Photograph, Photographer Unknown; Collection ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. Buckwheat Launder, date unknown Historic Photograph, Photographer Unknown; Collection of William Everett, Jr. (Wilkes-Barre, PA), photocopy by Joseph E.B. Elliot - Huber Coal Breaker, 101 South Main Street, Ashley, Luzerne County, PA

  18. 22. Photocopy of photograph (photographer unknown, date unknown, original print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. Photocopy of photograph (photographer unknown, date unknown, original print in possession of National Park Service, Petrified Forest National Park), EROSION CONTROL IN RIVER NEAR BRIDGE. - Rio Puerco Bridge, Mainline Road, spanning Rio Puerco, Holbrook, Navajo County, AZ

  19. 6. Photocopy of photograph Photographer unknown, date unknown DETAIL OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Photocopy of photograph Photographer unknown, date unknown DETAIL OF BOTTOM OF DRUM, SHOWING DECORATIVE MOLDING OF DRUM AND ARCHES: NOTE EFFECT OF BOX BEAMS CREATED BY MOLDING - University of Kentucky, Carnegie Library, Lexington, Fayette County, KY

  20. 13. Photocopy of photograph (source unknown) ca. 1890, photographer unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. Photocopy of photograph (source unknown) ca. 1890, photographer unknown COURTHOUSE AND JAIL, FROM THE SOUTH - Allegheny County Courthouse & Jail, 436 Grant Street (Courthouse), 420 Ross Street (Jail), Pittsburgh, Allegheny County, PA

  1. 6. Photocopy of photograph (location of original negative unknown) Unknown, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Photocopy of photograph (location of original negative unknown) Unknown, Photographer, Date Unknown PERSPECTIVE VIEW OF SOUTH (FRONT) AND EAST SIDE DURING MOVE SHOWING HOUSE RAISED - Hamilton Grange, (Moved From) 237 West 141 Street to 141st Street & Amsterdam, New York County, NY

  2. 4. Photocopy of photograph (location of original negative unknown) Unknown, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. Photocopy of photograph (location of original negative unknown) Unknown, Photographer, Date Unknown PERSPECTIVE VIEW OF SOUTH (FRONT) AND EAST SIDE BEFORE HOUSE MOVED SHOWING THIRTEEN LIQUIDAMBAR TREES IN FOREGROUND - Hamilton Grange, (Moved From) 237 West 141 Street to 141st Street & Amsterdam, New York County, NY

  3. Comparison of a priori versus provisional heparin therapy on radial artery occlusion after transradial coronary angiography and patent hemostasis (from the PHARAOH Study).

    PubMed

    Pancholy, Samir B; Bertrand, Olivier F; Patel, Tejas

    2012-07-15

    Systemic anticoagulation decreases the risk of radial artery occlusion (RAO) after transradial catheterization and standard occlusive hemostasis. We compared the efficacy and safety of provisional heparin use only when the technique of patent hemostasis was not achievable to standard a priori heparin administration after radial sheath introduction. Patients referred for coronary angiography were randomized in 2 groups. In the a priori group, 200 patients received intravenous heparin (50 IU/kg) immediately after sheath insertion. In the provisional group, 200 patients did not receive heparin during the procedure. After sheath removal, hemostasis was obtained using a TR band (Terumo corporation, Tokyo, Japan) with a plethysmography-guided patent hemostasis technique. In the provisional group, no heparin was given if radial artery patency could be obtained and maintained. If radial patency was not achieved, a bolus of heparin (50 IU/kg) was given. Radial artery patency was evaluated at 24 hours (early RAO) and 30 days after the procedure (late RAO) by plethysmography. Patent hemostasis was obtained in 67% in the a priori group and 74% in the provisional group (p = 0.10). Incidence of RAO remained similar in the 2 groups at the early (7.5% vs 7.0%, p = 0.84) and late (4.5% vs 5.0%, p = 0.83) evaluations. Women, patients with diabetes, patients having not received heparin, and patients without radial artery patency during hemostasis had more RAO. By multivariate analysis, patent radial artery during hemostasis (odds ratio [OR] 0.03, 95% confidence interval [CI] 0.004 to 0.28, p = 0.002) and diabetes (OR 11, 95% CI 3 to 38,p <0.0001) were independent predictors of late RAO, whereas heparin was not (OR 0.45 95% CI 0.13 to 1.54, p = 0.20). In conclusion, our results suggest that maintenance of radial artery patency during hemostasis is the most important parameter to decrease the risk of RAO. In selected cases, provisional use of heparin appears feasible and safe when

  4. Using a priori contrasts for multivariate repeated-measures ANOVA to analyze thermoregulatory responses of the dibbler (Parantechinus apicalis; Marsupialia, Dasyuridae).

    PubMed

    Withers, Philip C; Cooper, Christine E

    2011-01-01

    Physiological studies often involve the repeated measurement of individuals over a range of ordered categorical conditions, for example, varying ambient temperature. We illustrate here the use of a priori contrasts for multivariate repeated-measures ANOVA by analyzing the thermal responses of various physiological variables for a small marsupial, the dibbler (Parantechinus apicalis). Our analyses showed that dibblers conform closely to the Scholander-Irving model of endothermy. Body temperature was constant at low air temperatures, was 36.3 ± 0.24°C at thermoneutrality (30°C), and increased at 35°C. Metabolic rate decreased with increasing ambient temperature to a basal rate of 0.619 ± 0.036 mL O(2) g(-1) h(-1) at 30°C; it extrapolated closely to thermoneutral body temperature. Increased oxygen demand at lower ambient temperature was met by increased respiratory minute volume, achieved by increased respiratory frequency and tidal volume; oxygen extraction was constant at about 19%. Evaporative water loss and wet and dry thermal conductance increased markedly at high ambient temperatures but not sufficiently to maintain constant body temperature. Relative water economy was similar to that of other small marsupials, increasing linearly at lower air temperatures with a point of relative water economy of 20.3°C. We conclude that a priori contrasts provide a statistically appropriate and powerful analysis that can be used routinely to statistically describe the pattern of response of physiological variables to a categorical factor and are especially useful for repeated-measures ANOVA designs common to many physiological studies.

  5. Feasibility of improving a priori regional climate model estimates of Greenland ice sheet surface mass loss through assimilation of measured ice surface temperatures

    NASA Astrophysics Data System (ADS)

    Navari, M.; Margulis, S. A.; Bateni, S. M.; Tedesco, M.; Alexander, P.; Fettweis, X.

    2016-01-01

    The Greenland ice sheet (GrIS) has been the focus of climate studies due to its considerable impact on sea level rise. Accurate estimates of surface mass fluxes would contribute to understanding the cause of its recent changes and would help to better estimate the past, current and future contribution of the GrIS to sea level rise. Though the estimates of the GrIS surface mass fluxes have improved significantly over the last decade, there is still considerable disparity between the results from different methodologies (e.g., Rae et al., 2012; Vernon et al., 2013). The data assimilation approach can merge information from different methodologies in a consistent way to improve the GrIS surface mass fluxes. In this study, an ensemble batch smoother data assimilation approach was developed to assess the feasibility of generating a reanalysis estimate of the GrIS surface mass fluxes via integrating remotely sensed ice surface temperature measurements with a regional climate model (a priori) estimate. The performance of the proposed methodology for generating an improved posterior estimate was investigated within an observing system simulation experiment (OSSE) framework using synthetically generated ice surface temperature measurements. The results showed that assimilation of ice surface temperature time series were able to overcome uncertainties in near-surface meteorological forcing variables that drive the GrIS surface processes. Our findings show that the proposed methodology is able to generate posterior reanalysis estimates of the surface mass fluxes that are in good agreement with the synthetic true estimates. The results also showed that the proposed data assimilation framework improves the root-mean-square error of the posterior estimates of runoff, sublimation/evaporation, surface condensation, and surface mass loss fluxes by 61, 64, 76, and 62 %, respectively, over the nominal a priori climate model estimates.

  6. Learning for an Unknown Future

    ERIC Educational Resources Information Center

    Barnett, Ronald

    2012-01-01

    What is it to learn for an unknown future? It might be said that the future has always been unknown but this question surely takes on a new pedagogical challenge in the contemporary age. Generic skills may seem to offer the basis of just such a learning for an unknown future. Generic skills, by definition, are those that surely hold across…

  7. 7. Photocopy of photograph (location of original negative unknown) Unknown, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Photocopy of photograph (location of original negative unknown) Unknown, Photographer, Date Unknown PERSPECTIVE VIEW (SOUTHEAST) FROM ORIGINAL SITE SHOWING THIRTEEN LIQUIDAMBAR TREES (FOREGROUND) AND NORTH AND WEST SIDES OF HOUSE AS LOCATED AND ALTERED AT PRESENT SITE (ENTRANCE STAIRS FROM ORIGINAL SOUTH FRONT MOVED TO PRESENT WEST FRONT) - Hamilton Grange, (Moved From) 237 West 141 Street to 141st Street & Amsterdam, New York County, NY

  8. [Fever of unknown origin in adults].

    PubMed

    Lambertucci, José Roberto; Avila, Renata Eliane de; Voieta, Izabela

    2005-01-01

    Fever of unknown origin has been defined as axillary temperature higher than 37.8 degrees C on several occasions, persisting without diagnosis for at least 3 weeks in spite of at least 1 week's investigation in hospital. Lately, the definition has been modified and extended to reflect evolutionary changes in clinical practice. In response to this new evolving environment, cases of fever of unknown origin are currently classified as: classic, nosocomial, in neutropenia, and human immunodeficiency virus-related. The objective of our review was to try and define and to update the information on the subject.

  9. Identification of dietary patterns associated with obesity in a nationally representative survey of Canadian adults: application of a priori, hybrid, and simplified dietary pattern techniques.

    PubMed

    Jessri, Mahsa; Wolfinger, Russell D; Lou, Wendy Y; L'Abbé, Mary R

    2017-03-01

    Background: Analyzing the effects of dietary patterns is an important approach for examining the complex role of nutrition in the etiology of obesity and chronic diseases.Objectives: The objectives of this study were to characterize the dietary patterns of Canadians with the use of a priori, hybrid, and simplified dietary pattern techniques, and to compare the associations of these patterns with obesity risk in individuals with and without chronic diseases (unhealthy and healthy obesity).Design: Dietary recalls from 11,748 participants (≥18 y of age) in the cross-sectional, nationally representative Canadian Community Health Survey 2.2 were used. A priori dietary pattern was characterized with the use of the previously validated 2015 Dietary Guidelines for Americans Adherence Index (DGAI). Weighted partial least squares (hybrid method) was used to derive an energy-dense (ED), high-fat (HF), low-fiber density (LFD) dietary pattern with the use of 38 food groups. The associations of derived dietary patterns with disease outcomes were then tested with the use of multinomial logistic regression.Results: An ED, HF, and LFD dietary pattern had high positive loadings for fast foods, carbonated drinks, and refined grains, and high negative loadings for whole fruits and vegetables (≥|0.17|). Food groups with a high loading were summed to form a simplified dietary pattern score. Moving from the first (healthiest) to the fourth (least healthy) quartiles of the ED, HF, and LFD pattern and the simplified dietary pattern scores was associated with increasingly elevated ORs for unhealthy obesity, with individuals in quartile 4 having an OR of 2.57 (95% CI: 1.75, 3.76) and 2.73 (95% CI: 1.88, 3.98), respectively (P-trend < 0.0001). Individuals who adhered the most to the 2015 DGAI recommendations (quartile 4) had a 53% lower OR of unhealthy obesity (P-trend < 0.0001). The associations of dietary patterns with healthy obesity and unhealthy nonobesity were weaker, albeit

  10. Learning for an Unknown Future

    ERIC Educational Resources Information Center

    Barnett, Ronald

    2004-01-01

    What is it to learn for an unknown future? It might be said that the future has always been unknown but our opening question surely takes on a new pedagogical challenge if not urgency in the contemporary age. Indeed, it could be said that our opening question has never been generally acknowledged to be a significant motivating curricular and…

  11. A coupled radiative transfer and diffusion approximation model for the solution of the forward problem and the a-priori fluorophore distribution estimation in fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Gorpas, D.; Yova, D.; Politopoulos, K.

    2009-02-01

    Although fluorescence imaging has been applied in tumour diagnosis from the early 90s, just the last few years it has met an increasing scientific interest due to the advances in the biophotonics field and the combined technological progress of the acquisition and computational systems. In addition there are expectations that fluorescence imaging will be further developed and applied in deep tumour diagnosis in the years to come. However, this evolving field of imaging sciences has still to encounter important challenges. Among them is the expression of an accurate forward model for the solution of the reconstruction problem. The scope of this work is to introduce a three dimensional coupled radiative transfer and diffusion approximation model, applicable on the fluorescence imaging. Furthermore, the solver incorporates the super-ellipsoid models and sophisticated image processing algorithms to additionally provide a-priori estimation about the fluorophores distribution, information that is very important for the solution of the inverse problem. Simulation experiments have proven that the proposed methodology preserves the accuracy levels of the radiative transfer equation and the time efficacy of the diffusion approximation, while in the same time shows extended success on the registration between acquired and simulated images.

  12. Using models to guide field experiments: a priori predictions for the CO 2 response of a nutrient- and water-limited native Eucalypt woodland

    DOE PAGES

    Medlyn, Belinda E.; De Kauwe, Martin G.; Zaehle, Sönke; ...

    2016-05-09

    One major uncertainty in Earth System models is the response of terrestrial ecosystems to rising atmospheric CO2 concentration (Ca), particularly under nutrient-lim- ited conditions. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment, recently established in a nutrient- and water-limited woodlands, presents a unique opportunity to address this uncertainty, but can best do so if key model uncertainties have been identified in advance. Moreover, we applied seven vegetation models, which have previously been comprehensively assessed against earlier forest FACE experi- ments, to simulate a priori possible outcomes from EucFACE. Our goals were to provide quantitative projections against which to evaluate data asmore » they are collected, and to identify key measurements that should be made in the experiment to allow discrimination among alternative model assumptions in a postexperiment model intercompari- son. Simulated responses of annual net primary productivity (NPP) to elevated Ca ranged from 0.5 to 25% across models. The simulated reduction of NPP during a low-rainfall year also varied widely, from 24 to 70%. Key processes where assumptions caused disagreement among models included nutrient limitations to growth; feedbacks to nutri- ent uptake; autotrophic respiration; and the impact of low soil moisture availability on plant processes. Finally, knowledge of the causes of variation among models is now guiding data collection in the experiment, with the expectation that the experimental data can optimally inform future model improvements.« less

  13. Repeated evolution of net venation and fleshy fruits among monocots in shaded habitats confirms a priori predictions: evidence from an ndhF phylogeny

    PubMed Central

    Givnish, Thomas J; Pires, J. Chris; Graham, Sean W; McPherson, Marc A; Prince, Linda M; Patterson, Thomas B; Rai, Hardeep S; Roalson, Eric H; Evans, Timothy M; Hahn, William J; Millam, Kendra C; Meerow, Alan W; Molvray, Mia; Kores, Paul J; O'Brien, Heath E; Hall, Jocelyn C; Kress, W. John; Sytsma, Kenneth J

    2005-01-01

    We present a well-resolved, highly inclusive phylogeny for monocots, based on ndhF sequence variation, and use it to test a priori hypotheses that net venation and vertebrate-dispersed fleshy fruits should undergo concerted convergence, representing independent but often concurrent adaptations to shaded conditions. Our data demonstrate that net venation arose at least 26 times and was lost eight times over the past 90 million years; fleshy fruits arose at least 21 times and disappeared 11 times. Both traits show a highly significant pattern of concerted convergence (p<10−9), arising 16 times and disappearing four times in tandem. This phenomenon appears driven by even stronger tendencies for both traits to evolve in shade and be lost in open habitats (p<10−13–10−29). These patterns are among the strongest ever demonstrated for evolutionary convergence in individual traits and the predictability of evolution, and the strongest evidence yet uncovered for concerted convergence. The rate of adaptive shifts per taxon has declined exponentially over the past 90 million years, as expected when large-scale radiations fill adaptive zones. PMID:16011923

  14. A Priori Analysis of Subgrid Mass Flux Vectors from Massively Parallel Direct Numerical Simulations of High Pressure H2/O2 Reacting Shear Layers

    NASA Astrophysics Data System (ADS)

    Foster, Justin; Miller, Richard

    2011-11-01

    Direct Numerical Simulations (DNS) are conducted for temporally developing reacting H2/O2 shear layers at an ambient pressure of 100atm. The compressible form of the governing equations are coupled with the Peng Robinson real gas equation of state and are solved using eighth order central finite differences and fourth order Runge Kutta time integration with resolutions up to ~3/4 billion grid points. The formulation includes a detailed pressure dependent kinetics mechanism having 8 species and 19 steps, detailed property models, and generalized forms of the multicomponent heat and mass diffusion vectors derived from nonequilibrium thermodynamics and fluctuation theory. The DNS is performed over a range of Reynolds numbers up to 4500 based on the free stream velocity difference and initial vorticity thickness. The results are then analyzed in an a priori manner to illustrate the role of the subgrid mass flux vector within the filtered form of the governing equations relevant to Large Eddy Simulations. The subgrid mass flux vector is found to be a significant term; particularly within localized regions of the flame. Research supported by NSF Grant CBET-0965624 and Clemson University's Palmetto Cluster.

  15. Advancing techniques to constrain the geometry of the seismic rupture plane on subduction interfaces a priori: Higher-order functional fits

    USGS Publications Warehouse

    Hayes, G.P.; Wald, D.J.; Keranen, K.

    2009-01-01

    Ongoing developments in earthquake source inversions incorporate nonplanar fault geometries as inputs to the inversion process, improving previous approaches that relied solely on planar fault surfaces. This evolution motivates advancing the existing framework for constraining fault geometry, particularly in subduction zones where plate boundary surfaces that host highly hazardous earthquakes are clearly nonplanar. Here, we improve upon the existing framework for the constraint of the seismic rupture plane of subduction interfaces by incorporating active seismic and seafloor sediment thickness data with existing independent data sets and inverting for the most probable nonplanar subduction geometry. Constraining the rupture interface a priori with independent geological and seismological information reduces the uncertainty in the derived earthquake source inversion parameters over models that rely on simpler assumptions, such as the moment tensor inferred fault plane. Examples are shown for a number of wellconstrained global locations. We expand the coverage of previous analyses to a more uniform global data set and show that even in areas of sparse data this approach is able to accurately constrain the approximate subduction geometry, particularly when aided with the addition of data from local active seismic surveys. In addition, we show an example of the integration of many two-dimensional profiles into a threedimensional surface for the Sunda subduction zone and introduce the development of a new global threedimensional subduction interface model: Slab1.0. ?? 2009 by the American Geophysical Union.

  16. Using models to guide field experiments: a priori predictions for the CO2 response of a nutrient- and water-limited native Eucalypt woodland.

    PubMed

    Medlyn, Belinda E; De Kauwe, Martin G; Zaehle, Sönke; Walker, Anthony P; Duursma, Remko A; Luus, Kristina; Mishurov, Mikhail; Pak, Bernard; Smith, Benjamin; Wang, Ying-Ping; Yang, Xiaojuan; Crous, Kristine Y; Drake, John E; Gimeno, Teresa E; Macdonald, Catriona A; Norby, Richard J; Power, Sally A; Tjoelker, Mark G; Ellsworth, David S

    2016-08-01

    The response of terrestrial ecosystems to rising atmospheric CO2 concentration (Ca ), particularly under nutrient-limited conditions, is a major uncertainty in Earth System models. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment, recently established in a nutrient- and water-limited woodland presents a unique opportunity to address this uncertainty, but can best do so if key model uncertainties have been identified in advance. We applied seven vegetation models, which have previously been comprehensively assessed against earlier forest FACE experiments, to simulate a priori possible outcomes from EucFACE. Our goals were to provide quantitative projections against which to evaluate data as they are collected, and to identify key measurements that should be made in the experiment to allow discrimination among alternative model assumptions in a postexperiment model intercomparison. Simulated responses of annual net primary productivity (NPP) to elevated Ca ranged from 0.5 to 25% across models. The simulated reduction of NPP during a low-rainfall year also varied widely, from 24 to 70%. Key processes where assumptions caused disagreement among models included nutrient limitations to growth; feedbacks to nutrient uptake; autotrophic respiration; and the impact of low soil moisture availability on plant processes. Knowledge of the causes of variation among models is now guiding data collection in the experiment, with the expectation that the experimental data can optimally inform future model improvements. © 2016 John Wiley & Sons Ltd.

  17. Learned navigation in unknown terrains: A retraction method

    NASA Technical Reports Server (NTRS)

    Rao, Nageswara S. V.; Stoltzfus, N.; Iyengar, S. Sitharama

    1989-01-01

    The problem of learned navigation of a circular robot R, of radius delta (is greater than or equal to 0), through a terrain whose model is not a-priori known is considered. Two-dimensional finite-sized terrains populated by an unknown (but, finite) number of simple polygonal obstacles are also considered. The number and locations of the vertices of each obstacle are unknown to R. R is equipped with a sensor system that detects all vertices and edges that are visible from its present location. In this context two problems are covered. In the visit problem, the robot is required to visit a sequence of destination points, and in the terrain model acquisition problem, the robot is required to acquire the complete model of the terrain. An algorithmic framework is presented for solving these two problems using a retraction of the freespace onto the Voronoi diagram of the terrain. Algorithms are then presented to solve the visit problem and the terrain model acquisition problem.

  18. A priori and a posteriori investigations for developing large eddy simulations of multi-species turbulent mixing under high-pressure conditions

    SciTech Connect

    Borghesi, Giulio; Bellan, Josette

    2015-03-15

    A Direct Numerical Simulation (DNS) database was created representing mixing of species under high-pressure conditions. The configuration considered is that of a temporally evolving mixing layer. The database was examined and analyzed for the purpose of modeling some of the unclosed terms that appear in the Large Eddy Simulation (LES) equations. Several metrics are used to understand the LES modeling requirements. First, a statistical analysis of the DNS-database large-scale flow structures was performed to provide a metric for probing the accuracy of the proposed LES models as the flow fields obtained from accurate LESs should contain structures of morphology statistically similar to those observed in the filtered-and-coarsened DNS (FC-DNS) fields. To characterize the morphology of the large-scales structures, the Minkowski functionals of the iso-surfaces were evaluated for two different fields: the second-invariant of the rate of deformation tensor and the irreversible entropy production rate. To remove the presence of the small flow scales, both of these fields were computed using the FC-DNS solutions. It was found that the large-scale structures of the irreversible entropy production rate exhibit higher morphological complexity than those of the second invariant of the rate of deformation tensor, indicating that the burden of modeling will be on recovering the thermodynamic fields. Second, to evaluate the physical effects which must be modeled at the subfilter scale, an a priori analysis was conducted. This a priori analysis, conducted in the coarse-grid LES regime, revealed that standard closures for the filtered pressure, the filtered heat flux, and the filtered species mass fluxes, in which a filtered function of a variable is equal to the function of the filtered variable, may no longer be valid for the high-pressure flows considered in this study. The terms requiring modeling are the filtered pressure, the filtered heat flux, the filtered pressure work

  19. Genetic basis of delay discounting in frequent gamblers: examination of a priori candidates and exploration of a panel of dopamine-related loci

    PubMed Central

    Gray, Joshua C; MacKillop, James

    2014-01-01

    Introduction Delay discounting is a behavioral economic index of impulsivity that reflects preferences for small immediate rewards relative to larger delayed rewards. It has been consistently linked to pathological gambling and other forms of addictive behavior, and has been proposed to be a behavioral characteristic that may link genetic variation and risk of developing addictive disorders (i.e., an endophenotype). Studies to date have revealed significant associations with polymorphisms associated with dopamine neurotransmission. The current study examined associations between delay discounting and both previously linked variants and a novel panel of dopamine-related variants in a sample of frequent gamblers. Methods Participants were 175 weekly gamblers of European ancestry who completed the Monetary Choice Questionnaire to assess delay discounting preferences and provided a DNA via saliva. Results In a priori tests, two loci previously associated with delayed reward discounting (rs1800497 and rs4680) were not replicated, however, the long form of DRD4 VNTR was significantly associated with lower discounting of delayed rewards. Exploratory analysis of the dopamine-related panel revealed 11 additional significant associations in genes associated with dopamine synthesis, breakdown, reuptake, and receptor function (DRD3, SLC6A3, DDC, DBH, and SLC18A2). An aggregate genetic risk score from the nominally significant loci accounted for 17% of the variance in discounting. Mediational analyses largely supported the presence of indirect effects between the associated loci, delay discounting, and pathological gambling severity. Conclusions These findings do not replicate previously reported associations but identify several novel candidates and provide preliminary support for a systems biology approach to understand the genetic basis of delay discounting. PMID:25365808

  20. Chromosomal microarray analysis as a first-line test in pregnancies with a priori low risk for the detection of submicroscopic chromosomal abnormalities

    PubMed Central

    Fiorentino, Francesco; Napoletano, Stefania; Caiazzo, Fiorina; Sessa, Mariateresa; Bono, Sara; Spizzichino, Letizia; Gordon, Anthony; Nuccitelli, Andrea; Rizzo, Giuseppe; Baldi, Marina

    2013-01-01

    In this study, we aimed to explore the utility of chromosomal microarray analysis (CMA) in groups of pregnancies with a priori low risk for detection of submicroscopic chromosome abnormalities, usually not considered an indication for testing, in order to assess whether CMA improves the detection rate of prenatal chromosomal aberrations. A total of 3000 prenatal samples were processed in parallel using both whole-genome CMA and conventional karyotyping. The indications for prenatal testing included: advanced maternal age, maternal serum screening test abnormality, abnormal ultrasound findings, known abnormal fetal karyotype, parental anxiety, family history of a genetic condition and cell culture failure. The use of CMA resulted in an increased detection rate regardless of the indication for analysis. This was evident in high risk groups (abnormal ultrasound findings and abnormal fetal karyotype), in which the percentage of detection was 5.8% (7/120), and also in low risk groups, such as advanced maternal age (6/1118, 0.5%), and parental anxiety (11/1674, 0.7%). A total of 24 (0.8%) fetal conditions would have remained undiagnosed if only a standard karyotype had been performed. Importantly, 17 (0.6%) of such findings would have otherwise been overlooked if CMA was offered only to high risk pregnancies.The results of this study suggest that more widespread CMA testing of fetuses would result in a higher detection of clinically relevant chromosome abnormalities, even in low risk pregnancies. Our findings provide substantial evidence for the introduction of CMA as a first-line diagnostic test for all pregnant women undergoing invasive prenatal testing, regardless of risk factors. PMID:23211699

  1. An Approach for the Long-Term 30-m Land Surface Snow-Free Albedo Retrieval from Historic Landsat Surface Reflectance and MODIS-based A Priori Anisotropy Knowledge

    NASA Technical Reports Server (NTRS)

    Shuai, Yanmin; Masek, Jeffrey G.; Gao, Feng; Schaaf, Crystal B.; He, Tao

    2014-01-01

    Land surface albedo has been recognized by the Global Terrestrial Observing System (GTOS) as an essential climate variable crucial for accurate modeling and monitoring of the Earth's radiative budget. While global climate studies can leverage albedo datasets from MODIS, VIIRS, and other coarse-resolution sensors, many applications in heterogeneous environments can benefit from higher-resolution albedo products derived from Landsat. We previously developed a "MODIS-concurrent" approach for the 30-meter albedo estimation which relied on combining post-2000 Landsat data with MODIS Bidirectional Reflectance Distribution Function (BRDF) information. Here we present a "pre-MODIS era" approach to extend 30-m surface albedo generation in time back to the 1980s, through an a priori anisotropy Look-Up Table (LUT) built up from the high quality MCD43A BRDF estimates over representative homogenous regions. Each entry in the LUT reflects a unique combination of land cover, seasonality, terrain information, disturbance age and type, and Landsat optical spectral bands. An initial conceptual LUT was created for the Pacific Northwest (PNW) of the United States and provides BRDF shapes estimated from MODIS observations for undisturbed and disturbed surface types (including recovery trajectories of burned areas and non-fire disturbances). By accepting the assumption of a generally invariant BRDF shape for similar land surface structures as a priori information, spectral white-sky and black-sky albedos are derived through albedo-to-nadir reflectance ratios as a bridge between the Landsat and MODIS scale. A further narrow-to-broadband conversion based on radiative transfer simulations is adopted to produce broadband albedos at visible, near infrared, and shortwave regimes.We evaluate the accuracy of resultant Landsat albedo using available field measurements at forested AmeriFlux stations in the PNW region, and examine the consistency of the surface albedo generated by this approach

  2. Earthquake relocation using a 3D a-priori geological velocity model from the western Alps to Corsica: Implication for seismic hazard

    NASA Astrophysics Data System (ADS)

    Béthoux, Nicole; Theunissen, Thomas; Beslier, Marie-Odile; Font, Yvonne; Thouvenot, François; Dessa, Jean-Xavier; Simon, Soazig; Courrioux, Gabriel; Guillen, Antonio

    2016-02-01

    The region between the inner zones of the Alps and Corsica juxtaposes an overthickened crust to an oceanic domain, which makes difficult to ascertain the focal depth of seismic events using routine location codes and average 1D velocity models. The aim of this article is to show that, even with a rather lose monitoring network, accurate routine locations can be achieved by using realistic 3D modelling and advanced location techniques. Previous earthquake tomography studies cover the whole region with spatial resolutions of several tens of kilometres on land, but they fail to resolve the marine domain due to the absence of station coverage and sparse seismicity. To overcome these limitations, we first construct a 3D a-priori P and S velocity model integrating known geophysical and geological information. Significant progress has been achieved in the 3D numerical modelling of complex geological structures by the development of dedicated softwares (e.g. 3D GeoModeller), capable at once of elaborating a 3D structural model from geological and geophysical constraints and, possibly, of refining it by inversion processes (Calcagno et al., 2008). Then, we build an arrival-time catalogue of 1500 events recorded from 2000 to 2011. Hypocentres are then located in this model using a numerical code based on the maximum intersection method (Font et al., 2004), updated by Theunissen et al. (2012), as well as another 3D location technique, the NonLinLoc software (Lomax and Curtis, 2001). The reduction of arrival-time residuals and uncertainties (dh, dz) with respect to classical 1D locations demonstrates the improved accuracy allowed by our approach and confirms the coherence of the 3D geological model built and used in this study. Our results are also compared with previous works that benefitted from the installation of dense temporary networks surrounding the studied epicentre area. The resulting 3D location catalogue allows us to improve the regional seismic hazard assessment

  3. A priori performance prediction in pharmaceutical wet granulation: testing the applicability of the nucleation regime map to a formulation with a broad size distribution and dry binder addition.

    PubMed

    Kayrak-Talay, Defne; Litster, James D

    2011-10-14

    In this study, Hapgood's nucleation regime map (Hapgood et al., 2003) was tested for a formulation that consists of an active pharmaceutical ingredient (API) of broad size distribution and a fine dry binder. Gabapentin was used as the API and hydroxypropyl cellulose (HPC) as the dry binder with deionized water as the liquid binder. The formulation was granulated in a 6l Diosna high shear granulator. The effect of liquid addition method (spray, dripping), liquid addition rate (29-245 g/min), total liquid content (2, 4 and 10%), and impeller speed (250 and 500 rpm) on the granule size distribution and lump formation were investigated. Standard methods were successfully used to characterize the process parameters (spray drop size, spray geometry and powder surface velocity) for calculating the dimensionless spray flux. However, the addition of dry binder had a very strong effect on drop penetration time that could not be predicted from simple capillary flow considerations. This is most likely due to preferential liquid penetration into the fine pores related to the dry binder particles and subsequent partial softening and dissolution of the binder. For systems containing a dry binder or other amorphous powders, it is recommended that drop penetration time be measured directly for the blended formulation and then scaled to the drop size during spraying. Using these approaches to characterize the key dimensionless groups (dimensionless spray flux and drop penetration time), Hapgood's nucleation regime map was successfully used to predict a priori the effect of process conditions on the quality of the granule size distribution as measured by lump formation and the span of the size distribution, both before and after wet massing for range of conditions studied. Wider granule size distributions and higher amount of lumps were obtained moving from intermediate to mechanical dispersion regime. Addition of the liquid in the dripping mode gave the broadest size distribution

  4. A retrospective cohort study on the risk of stroke in relation to a priori health knowledge level among people with type 2 diabetes mellitus in Taiwan.

    PubMed

    Lai, Yun-Ju; Hu, Hsiao-Yun; Lee, Ya-Ling; Ku, Po-Wen; Yen, Yung-Feng; Chu, Dachen

    2017-05-22

    Intervention of diabetes care education with regular laboratory check-up in outpatient visits showed long-term benefits to reduce the risk of macrovascular complications among people with type 2 diabetes. However, research on the level of a priori health knowledge to the prevention of diabetic complications in community settings has been scarce. We therefore aimed to investigate the association of health knowledge and stroke incidence in patients with type 2 diabetes in Taiwan. A nationally representative sample of general Taiwanese population was selected using a multistage systematic sampling process from Taiwan National Health Interview Survey (NHIS) in 2005. Subjects were interviewed by a standardized face-to-face questionnaire in the survey, obtaining information of demographics, socioeconomic status, family medical history, obesity, health behaviors, and 15-item health knowledge assessment. The NHIS dataset was linked to Taiwan National Health Insurance claims data to retrieve the diagnosis of type 2 diabetes in NHIS participants at baseline and identify follow-up incidence of stroke from 2005 to 2013. Univariate and multivariate Cox regressions were used to estimate the effect of baseline health knowledge level to the risk of stroke incidence among this group of people with type 2 diabetes. A total of 597 diabetic patients with a mean age of 51.28 years old and nearly half of males were analyzed. During the 9-year follow-up period, 65 new stroke cases were identified among them. Kaplan-Meier curves comparing the three groups of low/moderate/high knowledge levels revealed a statistical significance (p-value of log-rank test <0.01). After controlling for potential confounders, comparing to the group of low health knowledge level, the relative risk of stroke was significantly lower for those with moderate (adjusted hazard ratio [AHR] = 0.63; 95% CI, 0.33-1.19; p-value = 0.15) and high level of health knowledge (AHR = 0.43; 95% CI, 0.22-0.86; p

  5. 3-D multiobservable probabilistic inversion for the compositional and thermal structure of the lithosphere and upper mantle. I: a priori petrological information and geophysical observables

    NASA Astrophysics Data System (ADS)

    Afonso, J. C.; Fullea, J.; Griffin, W. L.; Yang, Y.; Jones, A. G.; D. Connolly, J. A.; O'Reilly, S. Y.

    2013-05-01

    Traditional inversion techniques applied to the problem of characterizing the thermal and compositional structure of the upper mantle are not well suited to deal with the nonlinearity of the problem, the trade-off between temperature and compositional effects on wave velocities, the nonuniqueness of the compositional space, and the dissimilar sensitivities of physical parameters to temperature and composition. Probabilistic inversions, on the other hand, offer a powerful formalism to cope with all these difficulties, while allowing for an adequate treatment of the intrinsic uncertainties associated with both data and physical theories. This paper presents a detailed analysis of the two most important elements controlling the outputs of probabilistic (Bayesian) inversions for temperature and composition of the Earth's mantle, namely the a priori information on model parameters, ρ(m), and the likelihood function, L(m). The former is mainly controlled by our current understanding of lithosphere and mantle composition, while the latter conveys information on the observed data, their uncertainties, and the physical theories used to relate model parameters to observed data. The benefits of combining specific geophysical datasets (Rayleigh and Love dispersion curves, body wave tomography, magnetotelluric, geothermal, petrological, gravity, elevation, and geoid), and their effects on L(m), are demonstrated by analyzing their individual and combined sensitivities to composition and temperature as well as their observational uncertainties. The dependence of bulk density, electrical conductivity, and seismic velocities to major-element composition is systematically explored using Monte Carlo simulations. We show that the dominant source of uncertainty in the identification of compositional anomalies within the lithosphere is the intrinsic nonuniqueness in compositional space. A general strategy for defining ρ(m) is proposed based on statistical analyses of a large database

  6. Homage to an unknown photographer.

    PubMed

    Blanco-Dávila, F

    1993-01-01

    The Daguerreotype is an integral part of modern history as artifact and witness to great events and forms the basis on which the first surgical photograph of an amputation was taken in North America, during the Mexican-American War between 1846 and 1847; however, its photographer remains unknown.

  7. Learning from the Unknown Student

    ERIC Educational Resources Information Center

    Barlow, Angela T.; Gerstenschlager, Natasha E.; Harmon, Shannon E.

    2016-01-01

    In this article, three instructional situations demonstrate the value of using an "unknown" student's work to allow the advancement of students' mathematical thinking as well as their engagement in the mathematical practice of critiquing the reasoning of others: (1) introducing alternative solution strategies; (2) critiquing inaccuracies…

  8. Celestin Freinet, the Unknown Reformer.

    ERIC Educational Resources Information Center

    Lee, William B.

    1983-01-01

    Although unknown in the United States, Celestin Freinet founded in France an influential educational reform movement, Ecole Moderne, based on four principles: (1) democratic values, (2) empiricism, (3) interaction with nature and life, and (4) work as a basic human need. (SK)

  9. Learning from the Unknown Student

    ERIC Educational Resources Information Center

    Barlow, Angela T.; Gerstenschlager, Natasha E.; Harmon, Shannon E.

    2016-01-01

    In this article, three instructional situations demonstrate the value of using an "unknown" student's work to allow the advancement of students' mathematical thinking as well as their engagement in the mathematical practice of critiquing the reasoning of others: (1) introducing alternative solution strategies; (2) critiquing inaccuracies…

  10. Radar detection of signals with unknown parameters in K-distributed clutter

    NASA Astrophysics Data System (ADS)

    Conte, E.; Longo, M.; Lops, M.; Ullo, S. L.

    1991-04-01

    The detection of signals with unknown parameters in correlated K-distributed noise, using the generalized Neyman-Pearson strategy, is considered. The a priori uncertainty on the signal is removed by performing a maximum likelihood estimate of the unknown parameters. The resulting receivers can be regarded as a generalization of the conventional detector, but for a zero-memory nonlinearity depending on the amplitude probability density function of the noise as well as on the number of integrated pulses. It is shown that the performance for uncorrelated observations is unaffected by the specific signal pattern, but depends only on the signal-to-noise ratio; moreover, the effect of the clutter correlation on the performance can be accounted for simply by a detection gain. A performance assessment, carried out by computer simulation, shows that the proposed receivers significantly out-perform conventional ones as the noise amplitude probability density function markedly deviates from the Rayleigh law.

  11. Massive ascites of unknown origin

    PubMed Central

    Yuan, Shi-Min

    2014-01-01

    Massive ascites of unknown origin is an uncommon condition, which represent a diagnostic challenge. Patients with delayed diagnosis and treatment may have a poor prognosis. A 22-year-old female was referred to this hospital due to a 4-year progressive abdominal distension with massive ascites of unknown origin. By thorough investigations, she was eventually diagnosed as chronic calcified constrictive pericarditis. She received pericardiectomy and had an uneventful postoperative course. With a few day paracentesis, ascites did not progress any more. She was doing well at 5-month follow-up and has returned to work. Extracardiac manifestations, such as massive ascites and liver cirrhosis, were rare in patients with constrictive pericarditis. Pericardiectomy can be a radical solution for the treatment of chronic constrictive pericarditis. In order to avoid delayed diagnosis and treatment, physicians have to bear in mind this rare manifestation of chronic calcified constrictive pericarditis. PMID:24600502

  12. The potential implications of reclaimed wastewater reuse for irrigation on the agricultural environment: The knowns and unknowns of the fate of antibiotics and antibiotic resistant bacteria and resistance genes - A review.

    PubMed

    Christou, Anastasis; Agüera, Ana; Bayona, Josep Maria; Cytryn, Eddie; Fotopoulos, Vasileios; Lambropoulou, Dimitra; Manaia, Célia M; Michael, Costas; Revitt, Mike; Schröder, Peter; Fatta-Kassinos, Despo

    2017-10-15

    The use of reclaimed wastewater (RWW) for the irrigation of crops may result in the continuous exposure of the agricultural environment to antibiotics, antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). In recent years, certain evidence indicate that antibiotics and resistance genes may become disseminated in agricultural soils as a result of the amendment with manure and biosolids and irrigation with RWW. Antibiotic residues and other contaminants may undergo sorption/desorption and transformation processes (both biotic and abiotic), and have the potential to affect the soil microbiota. Antibiotics found in the soil pore water (bioavailable fraction) as a result of RWW irrigation may be taken up by crop plants, bioaccumulate within plant tissues and subsequently enter the food webs; potentially resulting in detrimental public health implications. It can be also hypothesized that ARGs can spread among soil and plant-associated bacteria, a fact that may have serious human health implications. The majority of studies dealing with these environmental and social challenges related with the use of RWW for irrigation were conducted under laboratory or using, somehow, controlled conditions. This critical review discusses the state of the art on the fate of antibiotics, ARB and ARGs in agricultural environment where RWW is applied for irrigation. The implications associated with the uptake of antibiotics by plants (uptake mechanisms) and the potential risks to public health are highlighted. Additionally, knowledge gaps as well as challenges and opportunities are addressed, with the aim of boosting future research towards an enhanced understanding of the fate and implications of these contaminants of emerging concern in the agricultural environment. These are key issues in a world where the increasing water scarcity and the continuous appeal of circular economy demand answers for a long-term safe use of RWW for irrigation. Copyright © 2017 Elsevier

  13. Building an environment model using depth information

    NASA Technical Reports Server (NTRS)

    Roth-Tabak, Y.; Jain, Ramesh

    1989-01-01

    Modeling the environment is one of the most crucial issues for the development and research of autonomous robot and tele-perception. Though the physical robot operates (navigates and performs various tasks) in the real world, any type of reasoning, such as situation assessment, planning or reasoning about action, is performed based on information in its internal world. Hence, the robot's intentional actions are inherently constrained by the models it has. These models may serve as interfaces between sensing modules and reasoning modules, or in the case of telerobots serve as interface between the human operator and the distant robot. A robot operating in a known restricted environment may have a priori knowledge of its whole possible work domain, which will be assimilated in its World Model. As the information in the World Model is relatively fixed, an Environment Model must be introduced to cope with the changes in the environment and to allow exploring entirely new domains. Introduced here is an algorithm that uses dense range data collected at various positions in the environment to refine and update or generate a 3-D volumetric model of an environment. The model, which is intended for autonomous robot navigation and tele-perception, consists of cubic voxels with the possible attributes: Void, Full, and Unknown. Experimental results from simulations of range data in synthetic environments are given. The quality of the results show great promise for dealing with noisy input data. The performance measures for the algorithm are defined, and quantitative results for noisy data and positional uncertainty are presented.

  14. Efficient tomography with unknown detectors

    NASA Astrophysics Data System (ADS)

    Motka, L.; Paúr, M.; Řeháček, J.; Hradil, Z.; Sánchez-Soto, L. L.

    2017-09-01

    We compare the two main techniques used for estimating the state of a physical system from unknown measurements: standard detector tomography and data-pattern tomography. Adopting linear inversion as a fair benchmark, we show that the difference between these two protocols can be traced back to the nonexistence of the reverse-order law for pseudoinverses. We capitalise on this fact to identify regimes where the data-pattern approach outperforms the standard one and vice versa. We corroborate these conclusions with numerical simulations of relevant examples of quantum state tomography.

  15. Damage diagnosis algorithm using a sequential change point detection method with an unknown distribution for damage

    NASA Astrophysics Data System (ADS)

    Noh, Hae Young; Rajagopal, Ram; Kiremidjian, Anne S.

    2012-04-01

    This paper introduces a damage diagnosis algorithm for civil structures that uses a sequential change point detection method for the cases where the post-damage feature distribution is unknown a priori. This algorithm extracts features from structural vibration data using time-series analysis and then declares damage using the change point detection method. The change point detection method asymptotically minimizes detection delay for a given false alarm rate. The conventional method uses the known pre- and post-damage feature distributions to perform a sequential hypothesis test. In practice, however, the post-damage distribution is unlikely to be known a priori. Therefore, our algorithm estimates and updates this distribution as data are collected using the maximum likelihood and the Bayesian methods. We also applied an approximate method to reduce the computation load and memory requirement associated with the estimation. The algorithm is validated using multiple sets of simulated data and a set of experimental data collected from a four-story steel special moment-resisting frame. Our algorithm was able to estimate the post-damage distribution consistently and resulted in detection delays only a few seconds longer than the delays from the conventional method that assumes we know the post-damage feature distribution. We confirmed that the Bayesian method is particularly efficient in declaring damage with minimal memory requirement, but the maximum likelihood method provides an insightful heuristic approach.

  16. Previously unknown species of Aspergillus.

    PubMed

    Gautier, M; Normand, A-C; Ranque, S

    2016-08-01

    The use of multi-locus DNA sequence analysis has led to the description of previously unknown 'cryptic' Aspergillus species, whereas classical morphology-based identification of Aspergillus remains limited to the section or species-complex level. The current literature highlights two main features concerning these 'cryptic' Aspergillus species. First, the prevalence of such species in clinical samples is relatively high compared with emergent filamentous fungal taxa such as Mucorales, Scedosporium or Fusarium. Second, it is clearly important to identify these species in the clinical laboratory because of the high frequency of antifungal drug-resistant isolates of such Aspergillus species. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been shown to enable the identification of filamentous fungi with an accuracy similar to that of DNA sequence-based methods. As MALDI-TOF MS is well suited to the routine clinical laboratory workflow, it facilitates the identification of these 'cryptic' Aspergillus species at the routine mycology bench. The rapid establishment of enhanced filamentous fungi identification facilities will lead to a better understanding of the epidemiology and clinical importance of these emerging Aspergillus species. Based on routine MALDI-TOF MS-based identification results, we provide original insights into the key interpretation issues of a positive Aspergillus culture from a clinical sample. Which ubiquitous species that are frequently isolated from air samples are rarely involved in human invasive disease? Can both the species and the type of biological sample indicate Aspergillus carriage, colonization or infection in a patient? Highly accurate routine filamentous fungi identification is central to enhance the understanding of these previously unknown Aspergillus species, with a vital impact on further improved patient care.

  17. Identification of the flexural stiffness parameters of an orthotropic plate from the local dynamic equilibrium without a priori knowledge of the principal directions

    NASA Astrophysics Data System (ADS)

    Ablitzer, Frédéric; Pézerat, Charles; Lascoup, Bertrand; Brocail, Julien

    2017-09-01

    This paper proposes an inverse method to characterize orthotropic material properties from vibratory measurements on plate-like structures. The method is an adaptation of the Force Analysis Technique (FAT), which was originally developed to identify the external force distribution acting on a structure using its local discretized equation of motion. This method was recently adapted to the identification of elastic and damping properties of isotropic plates. In the present approach, the equation of motion of an orthotropic plate with respect to an arbitrary set of orthogonal axes is considered. The angle between the axes of the measurement mesh and the principal directions of orthotropy therefore explicitly appears in the equation and constitutes an unknown. A procedure to identify this angle together with the flexural stiffness parameters is proposed, as well as an automatic regularization procedure to overcome the high sensitivity of the inverse problem to measurement noise. The method is illustrated using simulated data. Experimental results shown on various structures demonstrate the ability of the method to simultaneously identify the principal orthotropy directions and the flexural stiffness parameters.

  18. [Archaeons--still unknown microorganisms].

    PubMed

    Efenberger, Magdalena; Brzezińska-Błaszczyk, Ewa; Wódz, Karolina

    2014-12-12

    Archaea is a group of microorganisms described by Carl Woese in 1977. Although Archaea have a similar cellular organization to bacteria, their cell wall and cell membrane are quite unique. Archaeal cell wall lacks peptidoglican and cell membrane is composed of ether-lipids which are far more stable than bacteria-specific esther-lipids. Besides, Archaea have some specific external structures, like: archaella, pili, hami and cannulae but their exact functions are still unclear. Most of Archaea obtain energy via anaerobic processes of simple inorganic or organic compounds, however some of these organisms are also able to generate methane in the process known as methanogesis. They reproduce by cell division or budding-like process and some studies demonstrated the mechanisms of genetic transfer such as conjugation, transduction and natural transformation for the Archaea. They are capable of forming biofilms also in interaction with bacteria. Some archaeons, such as Haloferax mediterranei and Sulfolobus islandicus can synthesize antimicrobial agents which are called archaeocins. In recent years huge progress has been made in understanding of Archaea but many aspects of their biology remain still unknown. In this review, we present recent advances in Archaea biology focusing mainly on archaeal morphology, metabolism and reproduction.

  19. A priori and a posteriori dietary patterns at the age of 1 year and body composition at the age of 6 years: the Generation R Study.

    PubMed

    Voortman, Trudy; Leermakers, Elisabeth T M; Franco, Oscar H; Jaddoe, Vincent W V; Moll, Henriette A; Hofman, Albert; van den Hooven, Edith H; Kiefte-de Jong, Jessica C

    2016-08-01

    Dietary patterns have been linked to obesity in adults, however, not much is known about this association in early childhood. We examined associations of different types of dietary patterns in 1-year-old children with body composition at school age in 2026 children participating in a population-based cohort study. Dietary intake at the age of 1 year was assessed with a food-frequency questionnaire. At the children's age of 6 years we measured their body composition with dual-energy X-ray absorptiometry and we calculated body mass index, fat mass index (FMI), and fat-free mass index (FFMI). Three dietary pattern approaches were used: (1) An a priori-defined diet quality score; (2) dietary patterns based on variation in food intake, derived from principal-component-analysis (PCA); and (3) dietary patterns based on variations in FMI and FFMI, derived with reduced-rank-regression (RRR). Both the a priori-defined diet score and a 'Health-conscious' PCA-pattern were characterized by a high intake of fruit, vegetables, grains, and vegetable oils, and, after adjustment for confounders, children with higher adherence to these patterns had a higher FFMI at 6 years [0.19 SD (95 % CI 0.08;0.30) per SD increase in diet score], but had no different FMI. One of the two RRR-patterns was also positively associated with FFMI and was characterized by intake of whole grains, pasta and rice, and vegetable oils. Our results suggest that different a priori- and a posteriori-derived health-conscious dietary patterns in early childhood are associated with a higher fat-free mass, but not with fat mass, in later childhood.

  20. Towards Real-Time Global Localization in Dynamic Unstructured Environments

    NASA Astrophysics Data System (ADS)

    Tanaka, Kanji; Kondo, Eiji

    Global localization is the problem in which a mobile robot has to estimate the self-position with respect to an a priori given map as it navigates without using any a priori knowledge of the initial self-position. Previous studies on global localization mainly focused on static environments, where the a priori map is almost correct. On the other hand, in dynamic environments, there are several sources of computational complexity. For example, not only the self-position but also the map should be estimated due to the map errors. The main contribution of this paper is to address such computational complexity by decomposing our global localization problem into two smaller subproblems, and solving the subproblems in a practical computation time. Also, we demonstrate the robustness and the efficiency of the proposed method in various large and complex environments.

  1. Chronic lymphocytic leukaemias and non-Hodgkin's lymphomas by histological type in farming-animal breeding workers: a population case-control study based on a priori exposure matrices.

    PubMed Central

    Nanni, O; Amadori, D; Lugaresi, C; Falcini, F; Scarpi, E; Saragoni, A; Buiatti, E

    1996-01-01

    OBJECTIVES: A population based case-control study was conducted in a highly agricultural area in Italy to investigate the association between chronic lymphocytic leukaemias (CLLs) and non-Hodgkin's lymphomas (NHLs), and subtypes, and exposure to pesticides in farming-animal breeding workers. METHODS: 187 cases of CLLs and NHLs and 977 population controls were interviewed on medical, residential, family, and occupational history. Detailed information was collected about cultivated crops and animals bred from subjects who worked in farming and animal breeding. Information on crop diseases and pesticides used (and their quantity and duration) was also obtained. A priori job-exposure matrices were applied when a crop disease was reported, estimating the most probable pesticide and, when possible, an estimate of the cumulative dose. Odds ratios (ORs) were calculated by unconditional logistic analysis with adjustment for relevant confounders in farmers who bred animals and in farmers alone, for the main crops, types of animals, and pesticides categories. First recall and then the matrices were used for defining exposure, as it affected CLLs and NHLs and then separately on CLLs and low grade NHLs. Finally, the dose-response was investigated for those pesticides which had shown some association. RESULTS: No variable under study was associated with work in farming alone. In farming and animal breeding, no crop or animal showed an association with CLLs and NHLs when adjusted by exposure during childhood to farming and animal breeding (an indicator of life in a farming and animal breeding environment before the age of 13, which behaved as an independent risk variable). A non-significant association was found with stannates, arsenates, phosphates, and dichloro-diphenyl-trichloroethane (DDT) based on recall, and for stannates, arsenates, and DDT after the application of the matrices. When CLLs together with low grade NHLs were considered, the association with insecticides in

  2. Human-Robot Teams for Unknown and Uncertain Environments

    NASA Technical Reports Server (NTRS)

    Fong, Terry

    2015-01-01

    Man-robot interaction is the study of interactions between humans and robots. It is often referred as HRI by researchers. Human-robot interaction is a multidisciplinary field with contributions from human-computer interaction, artificial intelligence.

  3. Distributed Lag Models: Examining Associations Between the Built Environment and Health.

    PubMed

    Baek, Jonggyu; Sánchez, Brisa N; Berrocal, Veronica J; Sanchez-Vaznaugh, Emma V

    2016-01-01

    Built environment factors constrain individual level behaviors and choices, and thus are receiving increasing attention to assess their influence on health. Traditional regression methods have been widely used to examine associations between built environment measures and health outcomes, where a fixed, prespecified spatial scale (e.g., 1 mile buffer) is used to construct environment measures. However, the spatial scale for these associations remains largely unknown and misspecifying it introduces bias. We propose the use of distributed lag models (DLMs) to describe the association between built environment features and health as a function of distance from the locations of interest and circumvent a-priori selection of a spatial scale. Based on simulation studies, we demonstrate that traditional regression models produce associations biased away from the null when there is spatial correlation among the built environment features. Inference based on DLMs is robust under a range of scenarios of the built environment. We use this innovative application of DLMs to examine the association between the availability of convenience stores near California public schools, which may affect children's dietary choices both through direct access to junk food and exposure to advertisement, and children's body mass index z scores.

  4. Distributed Lag Models: Examining Associations between the Built Environment and Health

    PubMed Central

    Baek, Jonggyu; Sánchez, Brisa N.; Berrocal, Veronica J.; Sanchez-Vaznaugh, Emma V.

    2016-01-01

    Built environment factors constrain individual level behaviors and choices, and thus are receiving increasing attention to assess their influence on health. Traditional regression methods have been widely used to examine associations between built environment measures and health outcomes, where a fixed, pre-specified spatial scale (e.g., 1 mile buffer) is used to construct environment measures. However, the spatial scale for these associations remains largely unknown and misspecifying it introduces bias. We propose the use of distributed lag models (DLMs) to describe the association between built environment features and health as a function of distance from the locations of interest and circumvent a-priori selection of a spatial scale. Based on simulation studies, we demonstrate that traditional regression models produce associations biased away from the null when there is spatial correlation among the built environment features. Inference based on DLMs is robust under a range of scenarios of the built environment. We use this innovative application of DLMs to examine the association between the availability of convenience stores near California public schools, which may affect children’s dietary choices both through direct access to junk food and exposure to advertisement, and children’s body mass index z-scores (BMIz). PMID:26414942

  5. A Whole-Brain Voxel Based Measure of Intrinsic Connectivity Contrast Reveals Local Changes in Tissue Connectivity with Anesthetic without A Priori Assumptions on Thresholds or Regions of Interest

    PubMed Central

    Martuzzi, Roberto; Ramani, Ramachandran; Qiu, Maolin; Shen, Xilin; Papademetris, Xenophon; Constable, R. Todd

    2011-01-01

    The analysis of spontaneous fluctuations of functional magnetic resonance imaging (fMRI) signals has recently gained attention as a powerful tool for investigating brain circuits in a non-invasive manner. Correlation-based connectivity analysis investigates the correlations of spontaneous fluctuations of the fMRI signal either between a single seed region of interest (ROI) and the rest of the brain or between multiple ROIs. To do this, a priori knowledge is required for defining the ROI(s) and without such knowledge functional connectivity fMRI cannot be used as an exploratory tool for investigating the functional organization of the brain and its modulation under the different conditions. In this work we examine two indices that provide voxel based maps reflecting the intrinsic connectivity contrast (ICC) of individual tissue elements without the need for defining ROIs and hence require no a priori information or assumptions. These voxel based ICC measures can also be used to delineate regions of interest for further functional or network analyses. The indices were applied to the study of sevoflurane anesthesia-induced alterations in intrinsic connectivity. In concordance with previous studies, the results show that sevoflurane affects different brain circuits in a heterogeneous manner. In addition ICC analyses revealed changes in regions not previously identified using conventional ROI connectivity analyses, probably because of an inappropriate choice of the ROI in the earlier studies. This work highlights the importance of such voxel based connectivity methodology. PMID:21763437

  6. Fever of unknown origin: a clinical approach.

    PubMed

    Cunha, Burke A; Lortholary, Olivier; Cunha, Cheston B

    2015-10-01

    Fevers of unknown origin remain one of the most difficult diagnostic challenges in medicine. Because fever of unknown origin may be caused by over 200 malignant/neoplastic, infectious, rheumatic/inflammatory, and miscellaneous disorders, clinicians often order non-clue-based imaging and specific testing early in the fever of unknown origin work-up, which may be inefficient/misleading. Unlike most other fever-of-unknown-origin reviews, this article presents a clinical approach. Characteristic history and physical examination findings together with key nonspecific test abnormalities are the basis for a focused clue-directed fever of unknown origin work-up.

  7. Host suppression and bioinformatics for sequence-based characterization of unknown pathogens.

    SciTech Connect

    Branda, Steven S.; Lane, Todd W.; Misra, Milind; Meagher, Robert J.; Patel, Kamlesh D.; Kaiser, Julia N.

    2009-11-01

    Bioweapons and emerging infectious diseases pose formidable and growing threats to our national security. Rapid advances in biotechnology and the increasing efficiency of global transportation networks virtually guarantee that the United States will face potentially devastating infectious disease outbreaks caused by novel ('unknown') pathogens either intentionally or accidentally introduced into the population. Unfortunately, our nation's biodefense and public health infrastructure is primarily designed to handle previously characterized ('known') pathogens. While modern DNA assays can identify known pathogens quickly, identifying unknown pathogens currently depends upon slow, classical microbiological methods of isolation and culture that can take weeks to produce actionable information. In many scenarios that delay would be costly, in terms of casualties and economic damage; indeed, it can mean the difference between a manageable public health incident and a full-blown epidemic. To close this gap in our nation's biodefense capability, we will develop, validate, and optimize a system to extract nucleic acids from unknown pathogens present in clinical samples drawn from infected patients. This system will extract nucleic acids from a clinical sample, amplify pathogen and specific host response nucleic acid sequences. These sequences will then be suitable for ultra-high-throughput sequencing (UHTS) carried out by a third party. The data generated from UHTS will then be processed through a new data assimilation and Bioinformatic analysis pipeline that will allow us to characterize an unknown pathogen in hours to days instead of weeks to months. Our methods will require no a priori knowledge of the pathogen, and no isolation or culturing; therefore it will circumvent many of the major roadblocks confronting a clinical microbiologist or virologist when presented with an unknown or engineered pathogen.

  8. A Priori Calculations of Thermodynamic Functions

    DTIC Science & Technology

    1991-12-01

    hypothetical molecules (hydroxy-methyl- amino)nitro-methanol, 2,4,6,8-tetraazabicyclo-[3.3.0]octane, and 1,2,3-oxadiazolo-1,2,3- oxadiazole -1,1 -dioxide...C.010 rs 13,4 Oxadiazole 1.267 1.297h 0.030 rs 13,4 Thiadiazole 1.277 1.302 i 0.025 rs Diazomethane 1.288 1.300J 0.012 rs Pyrazole 1.309 1.331k 0.022...1.330f 0.018 ra Pyrazole 1.335 1.590.016 rs Dimethyl Nitramine 1 .365h 1.383i 0.018 r 1,3,4 Thladiazole 1.378 1.371i -0.007 r 1,3,4 Oxadiazole 1.402 1.9k

  9. Pyrexia of unknown origin in clinical practice.

    PubMed

    Bharucha, Tehmina; Cockbain, Beatrice; Brown, Michael

    2016-10-01

    This article revisits concepts of pyrexia of unknown origin to reflect current clinical practice. It describes the evolution of the term, in line with the changing spectrum and pace of investigations, and introduces key questions that may be used to evaluate a pyrexia of unknown origin.

  10. Deaths due to Unknown Foodborne Agents

    PubMed Central

    2004-01-01

    This study reviews the available evidence on unknown pathogenic agents transmitted in food and examines the methods that have been used to estimate that such agents cause 3,400 deaths per year in the United States. The estimate of deaths was derived from hospital discharge and death certificate data on deaths attributed to gastroenteritis of unknown cause. Fatal illnesses due to unknown foodborne agents do not always involve gastroenteritis, and gastroenteritis may not be accurately diagnosed or reported on hospital charts or death certificates. The death estimate consequently omitted deaths from unknown foodborne agents that do not cause gastroenteritis and likely overstated the number of deaths from agents that cause gastroenteritis. Although the number of deaths from unknown foodborne agents is uncertain, the possible economic cost of these deaths is so large that increased efforts to identify the causal agents are warranted. PMID:15498153

  11. Unknown Input and Sensor Fault Estimation Using Sliding-Mode Observers

    SciTech Connect

    Kalsi, Karanjit; Hui, Stefen; Zak, Stanislaw

    2011-06-29

    Sliding-mode observers are used to construct unknown input estimators. Then, these unknown input estimators are combined with sensor fault estimation schemes into one architecture that employs two sliding-mode observers for simultaneously estimating the plant’s actuator faults (part of the unknown input) and detecting sensor faults. Closed form expressions are presented for the estimates of unknown inputs and sensor faults. A benchmark example of a controlled inverted pendulum system from the literature is utilized in the simulation study. The study shows that the observers analyzed in this paper generate good estimates of the unknown input and sensor faults signals in noisy environments for nonlinear plants.

  12. Output feedback adaptive control of a class of nonlinear discrete-time systems with unknown control directions and preceded by hysteresis

    NASA Astrophysics Data System (ADS)

    Mohsen Hosseini-Ardali, Seyed; Ghaderi, Adel

    2015-11-01

    This paper considers the output feedback adaptive controller design problem for a class of discrete-time nonlinear systems in output feedback form with unknown control directions and preceded by unknown hysteresis. The problem of lacking in a-priori knowledge on the control directions and unknown hysteresis are solved by using the discrete Nussbaum gain and Prandtl-Ishlinskii model, respectively. The system is transformed into the form of a nonlinear auto regressive moving average (NARMA) model to construct an output feedback control. To overcome the noncausal problem in the control design, future output prediction laws and parameter update laws with the dead-zone technique are constructed on the basis of the NARMA model. The proposed control algorithm guarantees that all the signals in the controlled system are bound and the output tracking error is made to be neighbourhood around zero, ultimately. Finally, simulations are performed on a nonlinear system to show the effectiveness of the proposed method

  13. 53. Photographer unknown, date unknown. E.C. COLLIER under sail, dredging ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    53. Photographer unknown, date unknown. E.C. COLLIER under sail, dredging oysters. Please credit Chesapeake Bay Maritime Museum, St. Michaels, Maryland. - Two-Sail Bateau E. C. COLLIER, Chesapeake Bay Maritime Museum, Mills Street, Saint Michaels, Talbot County, MD

  14. Unknown, placeholder, or variable: what is x?

    NASA Astrophysics Data System (ADS)

    Ely, Robert; Adams, Anne E.

    2012-03-01

    One of the most significant steps in learning algebra is understanding the change in the role of letters in mathematical expressions from unknowns to variables. We describe the historical development of this change in usage, starting with the ancient use of mathematical unknowns, detailing several important changes in practice that allowed for the idea of the placeholder, the birth of symbolic algebra, and the development of the variable. Focusing on these changes in practice, we interpret some classroom examples of 8th-grade students who interpret letters in terms of their experience with unknowns, rather than in terms of variables, to the confusion and dismay of the teachers. We also discuss how particular curricular and pedagogical treatments can support student learning by deliberately focusing on these changes in practice in the transition from unknowns to variables in the middle grades.

  15. Controlled unknown quantum operations on hybrid systems

    NASA Astrophysics Data System (ADS)

    He, Yong; Luo, Ming-Xing

    2016-12-01

    Any unknown unitary operations conditioned on a control system can be deterministically performed if ancillary subspaces are available for the target systems [Zhou X Q, et al. 2011 Nat. Commun. 2 413]. In this paper, we show that previous optical schemes may be extended to general hybrid systems if unknown operations are provided by optical instruments. Moreover, a probabilistic scheme is proposed when the unknown operation may be performed on the subspaces of ancillary high-dimensional systems. Furthermore, the unknown operations conditioned on the multi-control system may be reduced to the case with a control system using additional linear circuit complexity. The new schemes may be more flexible for different systems or hybrid systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61303039 and 61201253), Chunying Fellowship, and Fundamental Research Funds for the Central Universities, China (Grant No. 2682014CX095).

  16. Quantum circuits cannot control unknown operations

    NASA Astrophysics Data System (ADS)

    Araújo, Mateus; Feix, Adrien; Costa, Fabio; Brukner, Časlav

    2014-09-01

    One of the essential building blocks of classical computer programs is the ‘if’ clause, which executes a subroutine depending on the value of a control variable. Similarly, several quantum algorithms rely on applying a unitary operation conditioned on the state of a control system. Here we show that this control cannot be performed by a quantum circuit if the unitary is completely unknown. The task remains impossible even if we allow the control to be done modulo a global phase. However, this no-go theorem does not prevent implementing quantum control of unknown unitaries in practice, as any physical implementation of an unknown unitary provides additional information that makes the control possible. We then argue that one should extend the quantum circuit formalism to capture this possibility in a straightforward way. This is done by allowing unknown unitaries to be applied to subspaces and not only to subsystems.

  17. Fever of unknown origin caused by tuberculosis.

    PubMed

    Bofinger, Jason J; Schlossberg, David

    2007-12-01

    Tuberculosis is an important cause of fever of unknown origin. Travel, age, dialysis, diabetes, birth in a country with a high prevalence of tuberculosis, and immunoincompetence are among the most salient risks. Associated physical findings, radiologic evaluation, and hematologic and endocrinologic abnormalities may provide clues to the diagnosis. Both noninvasive and invasive diagnostic modalities are reviewed. Because diagnosis may be elusive, therapeutic and diagnostic trials of antituberculous therapy should be considered in all patients with fever of unknown origin who defy diagnosis.

  18. Fever of unknown origin in rheumatic diseases.

    PubMed

    Zenone, Thierry

    2007-12-01

    Noninfectious inflammatory diseases (connective tissue diseases, vasculitis syndromes, granulomatous diseases) emerged as the most frequent cause of fever of unknown origin in western countries. Among these diseases, giant cell arteritis and polymyalgia rheumatica are the most frequent specific diagnosis in the elderly and adult-onset Still's disease the most frequent in younger patients. This article focuses on noninfectious inflammatory diseases as a cause of classic fever of unknown origin (mainly rheumatic diseases, such as vasculitis and connective tissue diseases).

  19. Using models to guide field experiments: a priori predictions for the CO 2 response of a nutrient- and water-limited native Eucalypt woodland

    SciTech Connect

    Medlyn, Belinda E.; De Kauwe, Martin G.; Zaehle, Sönke; Walker, Anthony P.; Duursma, Remko A.; Luus, Kristina; Mishurov, Mikhail; Pak, Bernard; Smith, Benjamin; Wang, Ying-Ping; Yang, Xiaojuan; Crous, Kristine Y.; Drake, John E.; Gimeno, Teresa E.; Macdonald, Catriona A.; Norby, Richard J.; Power, Sally A.; Tjoelker, Mark G.; Ellsworth, David S.

    2016-05-09

    One major uncertainty in Earth System models is the response of terrestrial ecosystems to rising atmospheric CO2 concentration (Ca), particularly under nutrient-lim- ited conditions. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment, recently established in a nutrient- and water-limited woodlands, presents a unique opportunity to address this uncertainty, but can best do so if key model uncertainties have been identified in advance. Moreover, we applied seven vegetation models, which have previously been comprehensively assessed against earlier forest FACE experi- ments, to simulate a priori possible outcomes from EucFACE. Our goals were to provide quantitative projections against which to evaluate data as they are collected, and to identify key measurements that should be made in the experiment to allow discrimination among alternative model assumptions in a postexperiment model intercompari- son. Simulated responses of annual net primary productivity (NPP) to elevated Ca ranged from 0.5 to 25% across models. The simulated reduction of NPP during a low-rainfall year also varied widely, from 24 to 70%. Key processes where assumptions caused disagreement among models included nutrient limitations to growth; feedbacks to nutri- ent uptake; autotrophic respiration; and the impact of low soil moisture availability on plant processes. Finally, knowledge of the causes of variation among models is now guiding data collection in the experiment, with the expectation that the experimental data can optimally inform future model improvements.

  20. Using models to guide field experiments: a priori predictions for the CO 2 response of a nutrient- and water-limited native Eucalypt woodland

    SciTech Connect

    Medlyn, Belinda E.; De Kauwe, Martin G.; Zaehle, Sönke; Walker, Anthony P.; Duursma, Remko A.; Luus, Kristina; Mishurov, Mikhail; Pak, Bernard; Smith, Benjamin; Wang, Ying-Ping; Yang, Xiaojuan; Crous, Kristine Y.; Drake, John E.; Gimeno, Teresa E.; Macdonald, Catriona A.; Norby, Richard J.; Power, Sally A.; Tjoelker, Mark G.; Ellsworth, David S.

    2016-05-09

    One major uncertainty in Earth System models is the response of terrestrial ecosystems to rising atmospheric CO2 concentration (Ca), particularly under nutrient-lim- ited conditions. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment, recently established in a nutrient- and water-limited woodlands, presents a unique opportunity to address this uncertainty, but can best do so if key model uncertainties have been identified in advance. Moreover, we applied seven vegetation models, which have previously been comprehensively assessed against earlier forest FACE experi- ments, to simulate a priori possible outcomes from EucFACE. Our goals were to provide quantitative projections against which to evaluate data as they are collected, and to identify key measurements that should be made in the experiment to allow discrimination among alternative model assumptions in a postexperiment model intercompari- son. Simulated responses of annual net primary productivity (NPP) to elevated Ca ranged from 0.5 to 25% across models. The simulated reduction of NPP during a low-rainfall year also varied widely, from 24 to 70%. Key processes where assumptions caused disagreement among models included nutrient limitations to growth; feedbacks to nutri- ent uptake; autotrophic respiration; and the impact of low soil moisture availability on plant processes. Finally, knowledge of the causes of variation among models is now guiding data collection in the experiment, with the expectation that the experimental data can optimally inform future model improvements.

  1. Design of a low-cost high-performance autonomous robot for nuclear environments

    SciTech Connect

    Burhanpurkar, V.P.

    1994-12-31

    This paper presents two key aspects of a novel low-cost modular mobile robot architecture for nuclear environments. Key features of the system are (a) a novel ultrasonic sensor for scene analysis in unstructured environments and (b) an efficient ground-search algorithm for ground-level contamination mapping without a priori maps or preprogramming.

  2. Creating a Superposition of Unknown Quantum States

    NASA Astrophysics Data System (ADS)

    Oszmaniec, Michał; Grudka, Andrzej; Horodecki, Michał; Wójcik, Antoni

    2016-03-01

    The superposition principle is one of the landmarks of quantum mechanics. The importance of quantum superpositions provokes questions about the limitations that quantum mechanics itself imposes on the possibility of their generation. In this work, we systematically study the problem of the creation of superpositions of unknown quantum states. First, we prove a no-go theorem that forbids the existence of a universal probabilistic quantum protocol producing a superposition of two unknown quantum states. Second, we provide an explicit probabilistic protocol generating a superposition of two unknown states, each having a fixed overlap with the known referential pure state. The protocol can be applied to generate coherent superposition of results of independent runs of subroutines in a quantum computer. Moreover, in the context of quantum optics it can be used to efficiently generate highly nonclassical states or non-Gaussian states.

  3. Bayesian modeling of unknown diseases for biosurveillance.

    PubMed

    Shen, Yanna; Cooper, Gregory F

    2009-11-14

    This paper investigates Bayesian modeling of unknown causes of events in the context of disease-outbreak detection. We introduce a Bayesian approach that models and detects both (1) known diseases (e.g., influenza and anthrax) by using informative prior probabilities and (2) unknown diseases (e.g., a new, highly contagious respiratory virus that has never been seen before) by using relatively non-informative prior probabilities. We report the results of simulation experiments which support that this modeling method can improve the detection of new disease outbreaks in a population. A key contribution of this paper is that it introduces a Bayesian approach for jointly modeling both known and unknown causes of events. Such modeling has broad applicability in medical informatics, where the space of known causes of outcomes of interest is seldom complete.

  4. Creating a Superposition of Unknown Quantum States.

    PubMed

    Oszmaniec, Michał; Grudka, Andrzej; Horodecki, Michał; Wójcik, Antoni

    2016-03-18

    The superposition principle is one of the landmarks of quantum mechanics. The importance of quantum superpositions provokes questions about the limitations that quantum mechanics itself imposes on the possibility of their generation. In this work, we systematically study the problem of the creation of superpositions of unknown quantum states. First, we prove a no-go theorem that forbids the existence of a universal probabilistic quantum protocol producing a superposition of two unknown quantum states. Second, we provide an explicit probabilistic protocol generating a superposition of two unknown states, each having a fixed overlap with the known referential pure state. The protocol can be applied to generate coherent superposition of results of independent runs of subroutines in a quantum computer. Moreover, in the context of quantum optics it can be used to efficiently generate highly nonclassical states or non-Gaussian states.

  5. Reconstruction of signals with unknown spectra in information field theory with parameter uncertainty

    SciTech Connect

    Ensslin, Torsten A.; Frommert, Mona

    2011-05-15

    The optimal reconstruction of cosmic metric perturbations and other signals requires knowledge of their power spectra and other parameters. If these are not known a priori, they have to be measured simultaneously from the same data used for the signal reconstruction. We formulate the general problem of signal inference in the presence of unknown parameters within the framework of information field theory. To solve this, we develop a generic parameter-uncertainty renormalized estimation (PURE) technique. As a concrete application, we address the problem of reconstructing Gaussian signals with unknown power-spectrum with five different approaches: (i) separate maximum-a-posteriori power-spectrum measurement and subsequent reconstruction, (ii) maximum-a-posteriori reconstruction with marginalized power-spectrum, (iii) maximizing the joint posterior of signal and spectrum, (iv) guessing the spectrum from the variance in the Wiener-filter map, and (v) renormalization flow analysis of the field-theoretical problem providing the PURE filter. In all cases, the reconstruction can be described or approximated as Wiener-filter operations with assumed signal spectra derived from the data according to the same recipe, but with differing coefficients. All of these filters, except the renormalized one, exhibit a perception threshold in case of a Jeffreys prior for the unknown spectrum. Data modes with variance below this threshold do not affect the signal reconstruction at all. Filter (iv) seems to be similar to the so-called Karhune-Loeve and Feldman-Kaiser-Peacock estimators for galaxy power spectra used in cosmology, which therefore should also exhibit a marginal perception threshold if correctly implemented. We present statistical performance tests and show that the PURE filter is superior to the others, especially if the post-Wiener-filter corrections are included or in case an additional scale-independent spectral smoothness prior can be adopted.

  6. [Fever of unknown cause and autoinflammatory disease].

    PubMed

    Hara, Toshiro

    2011-09-01

    Autoinflammatory diseases are often associated with various kinds of febrile episodes such as fever of unknown origin, periodic fever and recurrent fever. Therefore, in the differential diagnosis of fever of unknown cause, autoinflammatory diseases should be considered after exclusion of infections, malignancy and autoimmune diseases. As autoinflammatory diseases now include TRAPS (TNF receptor-associated periodic syndrome), CAPS (cryopyrin -associated periodic syndromes), FMF(familial Mediterranean fever), MAPS (mevalonate kinase-associated periodic fever syndrome, hyper-IgD syndrome) and many others, and show symptoms and signs of wide variations, we need to make an accurate diagnosis of them to prevent possible complications such as amyloidosis.

  7. Protocol for counterfactually transporting an unknown qubit

    NASA Astrophysics Data System (ADS)

    Salih, Hatim

    2015-12-01

    Quantum teleportation circumvents the uncertainty principle using dual channels: a quantum one consisting of previously-shared entanglement, and a classical one, together allowing the disembodied transport of an unknown quantum state over distance. It has recently been shown that a classical bit can be counterfactually communicated between two parties in empty space, “Alice” and “Bob”. Here, by using our “dual” version of the chained quantum Zeno effect to achieve a counterfactual CNOT gate, we propose a protocol for transporting an unknown qubit counterfactually, that is without any physical particles travelling between Alice and Bob—no classical channel and no previously-shared entanglement.

  8. Markov sequential pattern recognition : dependency and the unknown class.

    SciTech Connect

    Malone, Kevin Thomas; Haschke, Greg Benjamin; Koch, Mark William

    2004-10-01

    The sequential probability ratio test (SPRT) minimizes the expected number of observations to a decision and can solve problems in sequential pattern recognition. Some problems have dependencies between the observations, and Markov chains can model dependencies where the state occupancy probability is geometric. For a non-geometric process we show how to use the effective amount of independent information to modify the decision process, so that we can account for the remaining dependencies. Along with dependencies between observations, a successful system needs to handle the unknown class in unconstrained environments. For example, in an acoustic pattern recognition problem any sound source not belonging to the target set is in the unknown class. We show how to incorporate goodness of fit (GOF) classifiers into the Markov SPRT, and determine the worse case nontarget model. We also develop a multiclass Markov SPRT using the GOF concept.

  9. Adaptive synchronization of two chaotic systems with stochastic unknown parameters

    NASA Astrophysics Data System (ADS)

    Salarieh, Hassan; Alasty, Aria

    2009-02-01

    Using the Lyapunov stability theory an adaptive control is proposed for chaos synchronization between two different systems which have stochastically time varying unknown coefficients. The stochastic variations of the coefficients about their unknown mean values are modeled through white Gaussian noise produced by the Weiner process. It is shown that using the proposed adaptive control the mean square of synchronization error converges to an arbitrarily small bound around zero. To demonstrate the effectiveness of the proposed technique, it is applied to the Lorenz-Chen and the Chen-Rossler dynamical systems, as some case studies. Simulation results indicate that the proposed adaptive controller has a high performance in synchronization of chaotic systems in noisy environment.

  10. Method for genetic identification of unknown organisms

    DOEpatents

    Colston, Jr., Billy W.; Fitch, Joseph P.; Hindson, Benjamin J.; Carter, Chance J.; Beer, Neil Reginald

    2016-08-23

    A method of rapid, genome and proteome based identification of unknown pathogenic or non-pathogenic organisms in a complex sample. The entire sample is analyzed by creating millions of emulsion encapsulated microdroplets, each containing a single pathogenic or non-pathogenic organism sized particle and appropriate reagents for amplification. Following amplification, the amplified product is analyzed.

  11. Metastatic adenocarcinoma of unknown primary origin.

    PubMed

    Hammar, S P

    1998-12-01

    Adenocarcinomas account for up to 60% of all metastatic neoplasms of unknown primary origin. In general, adenocarcinomas are the most difficult metastatic tumor to accurately identify the primary site. Some metastatic adenocarcinomas have distinctive histological features that allow for their site determination (eg, colonic adenocarcinoma, bronchioloalveolar cell carcinoma), although the majority of metastatic adenocarcinomas have histological features that are not distinctive enough to allow for a specific diagnosis of their origin. For this reason, electron microscopy and immunohistochemistry have been used to help identify the exact type (origin) of metastatic adenocarcinomas. Relatively specific ultrastructural features used to diagnose metastatic adenocarcinomas of unknown primary origin include tubular myelin, intranuclear surfactant apoprotein tubular inclusions, Clara cell granules, uniform short microvilli with filamentous cores and core rootlets, Langerhans cells associated with neoplastic cells, cytoplasmic hyaline globules, lipid droplets, glycogen, and cytoplasmic crystals. Only a few of these ultrastructural features are absolutely specific. Relatively specific immunohistochemical tests used to diagnose metastatic adenocarcinomas of unknown primary origin include prostate-specific antigen, thyroglobulin, estrogen and progesterone receptor proteins, thyroid transcription factor-I, and surfactant apoproteins. Of these, prostate-specific antigen and thyroglobulin are the most specific. The purpose of this article is to discuss the use of electron microscopy and immunohistochemistry in the site-specific diagnosis of metastatic adenocarcinomas of unknown primary origin.

  12. Fever of unknown origin, with a twist

    PubMed Central

    Lobo, Ronstan; Meany, Brendan; O'Hanlon, Rory; Kiernan, Thomas John

    2013-01-01

    The authors present a case of an 81-year-old man with fever of unknown origin. The case report is illustrated with the images which clarified the diagnosis in this challenging case. The cardiac MR images were of critical importance in arriving at a diagnosis of aortic root mycotic pseudoaneurysm with rupture into the right ventricle. PMID:23345531

  13. Conquering the Unknown: Exploring the Options

    ERIC Educational Resources Information Center

    Baker, Lynne M.

    2012-01-01

    There are many challenges that lie ahead for families of children with special needs. It is indeed a time for conquering the unknown and diligently exploring the options in an effort to locate, understand, and ultimately embrace the as yet undiscovered beauties of the new setting. This paper will consider some of the issues relevant for parents,…

  14. The Use of a priori Information in ICA-Based Techniques for Real-Time fMRI: An Evaluation of Static/Dynamic and Spatial/Temporal Characteristics

    PubMed Central

    Soldati, Nicola; Calhoun, Vince D.; Bruzzone, Lorenzo; Jovicich, Jorge

    2013-01-01

    Real-time brain functional MRI (rt-fMRI) allows in vivo non-invasive monitoring of neural networks. The use of multivariate data-driven analysis methods such as independent component analysis (ICA) offers an attractive trade-off between data interpretability and information extraction, and can be used during both task-based and rest experiments. The purpose of this study was to assess the effectiveness of different ICA-based procedures to monitor in real-time a target IC defined from a functional localizer which also used ICA. Four novel methods were implemented to monitor ongoing brain activity in a sliding window approach. The methods differed in the ways in which a priori information, derived from ICA algorithms, was used to monitor a target independent component (IC). We implemented four different algorithms, all based on ICA. One Back-projection method used ICA to derive static spatial information from the functional localizer, off-line, which was then back-projected dynamically during the real-time acquisition. The other three methods used real-time ICA algorithms that dynamically exploited temporal, spatial, or spatial-temporal priors during the real-time acquisition. The methods were evaluated by simulating a rt-fMRI experiment that used real fMRI data. The performance of each method was characterized by the spatial and/or temporal correlation with the target IC component monitored, computation time, and intrinsic stochastic variability of the algorithms. In this study the Back-projection method, which could monitor more than one IC of interest, outperformed the other methods. These results are consistent with a functional task that gives stable target ICs over time. The dynamic adaptation possibilities offered by the other ICA methods proposed may offer better performance than the Back-projection in conditions where the functional activation shows higher spatial and/or temporal variability. PMID:23483841

  15. 14. Photocopy of photograph (source unknown) photographer unknown pre1885 NORTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Photocopy of photograph (source unknown) photographer unknown pre-1885 NORTH SIDE AND WEST FRONT (NOTE ABSENCE OF DORMER ON GAMBREL ROOF OF ELL) (Illustration #6 of Data Report included in Field Records) - Narbonne House, 71 Essex Street, Salem, Essex County, MA

  16. Robot navigation in unknown terrains: Introductory survey of non-heuristic algorithms

    SciTech Connect

    Rao, N.S.V.; Kareti, S.; Shi, Weimin; Iyengar, S.S.

    1993-07-01

    A formal framework for navigating a robot in a geometric terrain by an unknown set of obstacles is considered. Here the terrain model is not a priori known, but the robot is equipped with a sensor system (vision or touch) employed for the purpose of navigation. The focus is restricted to the non-heuristic algorithms which can be theoretically shown to be correct within a given framework of models for the robot, terrain and sensor system. These formulations, although abstract and simplified compared to real-life scenarios, provide foundations for practical systems by highlighting the underlying critical issues. First, the authors consider the algorithms that are shown to navigate correctly without much consideration given to the performance parameters such as distance traversed, etc. Second, they consider non-heuristic algorithms that guarantee bounds on the distance traversed or the ratio of the distance traversed to the shortest path length (computed if the terrain model is known). Then they consider the navigation of robots with very limited computational capabilities such as finite automata, etc.

  17. Multivariate statistical approach to estimate mixing proportions for unknown end members

    USGS Publications Warehouse

    Valder, Joshua F.; Long, Andrew J.; Davis, Arden D.; Kenner, Scott J.

    2012-01-01

    A multivariate statistical method is presented, which includes principal components analysis (PCA) and an end-member mixing model to estimate unknown end-member hydrochemical compositions and the relative mixing proportions of those end members in mixed waters. PCA, together with the Hotelling T2 statistic and a conceptual model of groundwater flow and mixing, was used in selecting samples that best approximate end members, which then were used as initial values in optimization of the end-member mixing model. This method was tested on controlled datasets (i.e., true values of estimates were known a priori) and found effective in estimating these end members and mixing proportions. The controlled datasets included synthetically generated hydrochemical data, synthetically generated mixing proportions, and laboratory analyses of sample mixtures, which were used in an evaluation of the effectiveness of this method for potential use in actual hydrological settings. For three different scenarios tested, correlation coefficients (R2) for linear regression between the estimated and known values ranged from 0.968 to 0.993 for mixing proportions and from 0.839 to 0.998 for end-member compositions. The method also was applied to field data from a study of end-member mixing in groundwater as a field example and partial method validation.

  18. [Fever of unknown origin in gastroenterology].

    PubMed

    Schneider, T; Daum, S; Loddenkemper, C; Zeitz, M

    2009-06-01

    The gastrointestinal tract may be of major clinical or diagnostic importance in fever of unknown origin. To the classical diseases in this sense belong very different diseases as Whipple's disease, Familiar Mediterranean Fever, isolated mesenterial vasculitis, and manifestations of immune reconstitution inflammatory disease, but also unusual manifestations of otherwise easily recognized diseases like special forms of celiac disease, or inflammatory bowel disease. Endoscopical techniques to obtain biopsies for diagnostic procedures are frequently crucial to solve the diagnostic puzzle. In some cases the bioptic material may not be sufficient to reach a diagnosis and further surgical intervention is necessary (intestinal lymph-nodes or bowel resections) to acquire enough tissue for a definite diagnosis. Nevertheless using these different approaches in most cases of fever of unknown origin the underlying cause can be identified which for many patients means not more or less than significant improvement or even survival.

  19. Venus atmospheric circulation - Known and unknown

    NASA Technical Reports Server (NTRS)

    Limaye, Sanjay Shridhar

    1990-01-01

    Temporally and longitudinally averaged circulation determined from images acquired since 1979 from the Pioneer Venus orbiter has shown significant changes in th meridional flow. The solar-locked structure in the zonal and meridional components of the cloud motions is also observed to change with time. Mechanisms for such changes remain unknown, although planetary waves and a slight modulation of the cloud level have been suggested as explanations. Decomposition of the solar-locked structure into diurnal and semidiurnal components suggests that nightside zonal flow may be 10-20 m/s faster than the average dayside flow. Many aspects of the circulation remain unknown, including the horizontal and vertical structure on the nightside and at levels higher and lower than the UV cloud features, sources, and sinks of UV absorbers, and meridional transports of heat, momentum, and water vapor at different levels.

  20. "Freud" and Bullitt: an unknown manuscript.

    PubMed

    Solms, Mark

    2006-01-01

    An English translation of a previously unknown manuscript by Freud is presented. The manuscript, originally prepared in 1931 for William Bullitt's psychobiography of Woodrow Wilson, provides a general theoretical introduction to psychoanalysis. It also includes an original interpretation of Christianity that postulates a deep-going continuity between Christ identification and latent homosexuality. An editorial introduction to the translation clarifies the nature and limits of Freud's involvement with Bullitt's controversial psychobiography.

  1. Fever of unknown origin (FUO) revised.

    PubMed

    Unger, Manuel; Karanikas, Georgios; Kerschbaumer, Andreas; Winkler, Stefan; Aletaha, Daniel

    2016-11-01

    Fever of unknown origin (FUO) was originally characterised in 1961 by Petersdorf and Beeson as a disease condition of temperature exceeding 38.3 °C on at least three occasions over a period of at least three weeks, with no diagnosis made despite one week of inpatient investigation. However, since underlying diseases are often reported for classical FUO, these presentations may not be considered to be of "unknown origin". Rather, the aetiology of prolonged fever may resolve, or not resolve. The definition of fever with unresolved cause (true FUO) is difficult, as it is a moving target, given the constant advancement of imaging and biomarker analysis. Therefore, the prevalence of fever with unresolved cause (FUO) is unknown.In this review, we report such a case of prolonged fever, which initially has presented as classical FUO, and discuss current literature. Furthermore, we will give an outlook, how a prospective study on FUO will allow to solve outstanding issues like the utility of different diagnostic investigations, and the types and prevalence of various underlying diseases.

  2. Neurofunctional Signature of Hyperfamiliarity for Unknown Faces

    PubMed Central

    Negro, Elisa; D’Agata, Federico; Caroppo, Paola; Coriasco, Mario; Ferrio, Federica; Celeghin, Alessia; Diano, Matteo; Rubino, Elisa; de Gelder, Beatrice; Rainero, Innocenzo; Pinessi, Lorenzo; Tamietto, Marco

    2015-01-01

    Hyperfamiliarity for unknown faces is a rare selective disorder that consists of the disturbing and abnormal feeling of familiarity for unknown faces, while recognition of known faces is normal. In one such patient we investigated with a multimodal neuroimaging design the hitherto undescribed neural signature associated with hyperfamiliarity feelings. Behaviorally, signal detection methods revealed that the patient’s discrimination sensitivity between familiar and unfamiliar faces was significantly lower than that of matched controls, and her response criterion for familiarity decisions was significantly more liberal. At the neural level, while morphometric analysis and single-photon emission CT (SPECT) showed the atrophy and hypofunctioning of the left temporal regions, functional magnetic resonance imaging (fMRI) revealed that hyperfamiliarity feelings were selectively associated to enhanced activity in the right medial and inferior temporal cortices. We therefore characterize the neurofunctional signature of hyperfamiliarity for unknown faces as related to the loss of coordinated activity between the complementary face processing functions of the left and right temporal lobes. PMID:26154253

  3. Environment arrays: a possible approach for predicting changes in waterborne bacterial disease potential.

    PubMed

    Heinemann, Jack A; Rosén, Håkan; Savill, Marion; Burgos-Caraballo, Sofia; Toranzos, Gary A

    2006-12-01

    Current molecular techniques for identifying bacteria in water have proven useful, but they are not reliably predictive of impending disease outbreaks. Genomics-based approaches will help to detect the presence of pathogens quickly and well before they grow into a population that poses a risk to public health. We suggest that genomics is only one component of the toolbox that will be needed to identify emerging waterborne threats. We propose a methodology beyond genomics, based on activity in the mobile genome. This approach makes use of a new device called an environment array. The array will depend upon the same research necessary for genomics-based detection, but will not require an a priori knowledge of virulence genes. Environment arrays are assembled from molecular profiles of the infectious elements that transfer between bacteria. The advantage of the array is that it monitors the activity of the mobile genome, rather than the presence of particular DNA sequences. Environmental arrays should thus be many times more sensitive than traditional hybridization or PCR-based techniques that target already-known DNA sequences. Mobile elements are known to respond to new environmental conditions that may correlate with a chemical contamination or the bloom of bacterial pathogens, potentially allowing for a much broader application in detecting unknown or unanticipated biological and chemical contaminants.

  4. Spacecraft Internal Acoustic Environment Modeling

    NASA Technical Reports Server (NTRS)

    Chu, SShao-sheng R.; Allen, Christopher S.

    2009-01-01

    Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. In FY09, the physical mockup developed in FY08, with interior geometric shape similar to Orion CM (Crew Module) IML (Interior Mode Line), was used to validate SEA (Statistical Energy Analysis) acoustic model development with realistic ventilation fan sources. The sound power levels of these sources were unknown a priori, as opposed to previous studies that RSS (Reference Sound Source) with known sound power level was used. The modeling results were evaluated based on comparisons to measurements of sound pressure levels over a wide frequency range, including the frequency range where SEA gives good results. Sound intensity measurement was performed over a rectangular-shaped grid system enclosing the ventilation fan source. Sound intensities were measured at the top, front, back, right, and left surfaces of the and system. Sound intensity at the bottom surface was not measured, but sound blocking material was placed tinder the bottom surface to reflect most of the incident sound energy back to the remaining measured surfaces. Integrating measured sound intensities over measured surfaces renders estimated sound power of the source. The reverberation time T6o of the mockup interior had been modified to match reverberation levels of ISS US Lab interior for speech frequency bands, i.e., 0.5k, 1k, 2k, 4 kHz, by attaching appropriately sized Thinsulate sound absorption material to the interior wall of the mockup. Sound absorption of Thinsulate was modeled in three methods: Sabine equation with measured mockup interior reverberation time T60, layup model based on past impedance tube testing, and layup model plus air absorption correction. The evaluation/validation was

  5. Chronic Traumatic Encephalopathy: Known Causes, Unknown Effects.

    PubMed

    Iacono, Diego; Shively, Sharon B; Edlow, Brian L; Perl, Daniel P

    2017-05-01

    Chronic traumatic encephalopathy (CTE) is a neuropathologic diagnosis typically made in human brains with a history of repetitive traumatic brain injury (rTBI). It remains unknown whether CTE occurs exclusively after rTBI, or whether a single TBI (sTBI) can cause CTE. Similarly, it is unclear whether impact (eg, motor vehicle accidents) and non-impact (eg, blasts) types of energy transfer trigger divergent or common pathologies. While it is established that a history of rTBI increases the risk of multiple neurodegenerative diseases (eg, dementia, parkinsonism, and CTE), the possible pathophysiologic and molecular mechanisms underlying these risks have yet to be elucidated. Published by Elsevier Inc.

  6. Multiple tendon ruptures of unknown etiology.

    PubMed

    Axibal, Derek P; Anderson, John G

    2013-10-01

    Tendon ruptures are common findings in foot and ankle practice. The etiology of tendon ruptures tends to be multifactorial-usually due to a combination of trauma, effects of systemic diseases, adverse effects of medications, and obesity. We present an unusual case of right Achilles tendinitis, left Achilles tendon rupture, bilateral peroneus longus tendon rupture, and left peroneus brevis tendon rupture of unknown etiology. This case report highlights the need for research for other possible, lesser known etiologies of tendon pathology. Therapeutic, Level IV, Case Study.

  7. Fever of unknown origin in cancer patients.

    PubMed

    Loizidou, A; Aoun, M; Klastersky, J

    2016-05-01

    Fever of unknown origin (FUO) remains a challenging clinical problem, namely in patients with cancer. In cancer patients, FUO may be due to the cancer itself, as it is the case of hematological malignancies; digestive tumors (colon cancer, liver metastases) are significantly associated with FUO and infection can be demonstrated in some cases. Prevention with G-CSF and empirical antimicrobial therapy are essential approaches for the management of FUO in cancer patients. New diagnostic approaches, such as PET imaging, should be further evaluated in cancer patients with FUO. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. Infectious causes of fever of unknown origin.

    PubMed

    McGregor, Alastair C; Moore, David A

    2015-06-01

    The causes of fever of unknown origin (FUO) are changing because advances in clinical practice and diagnostics have facilitated the identification of some infections. A variety of bacterial infections can cause FUO, and these can be divided into those that are easy to identify using culture and those that require serological or molecular tests for identification. A number of viral, parasitic and fungal infections can also cause prolonged fever. This article summarises the clinical features and diagnostic strategy of these infections. © Royal College of Physicians 2015. All rights reserved.

  9. Fever of Unknown Origin in Childhood.

    PubMed

    Chusid, Michael J

    2017-02-01

    Childhood fever of unknown origin (FUO) is most often related to an underlying infection but can also be associated with a variety of neoplastic, rheumatologic, and inflammatory conditions. Repeated, focused reviews of patient history and physical examination are often helpful in suggesting a likely diagnosis. Diagnostic workup should be staged, usually leaving invasive testing for last. Advances in molecular genetic techniques have increased the importance of these assays in the diagnosis of FUO in children. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Fever of unknown origin in older adults.

    PubMed

    Tal, Sari; Guller, Vladimir; Gurevich, Alexander

    2007-08-01

    Evaluation of elderly patients who have fever of unknown origin (FUO) requires a different perspective from that needed for young patients. Differential diagnosis often varies with age, and presentation of the disease frequently is nonspecific and symptoms difficult to interpret. Noninfectious diseases are the most frequent cause of FUO in the elderly and temporal arteritis the most frequent specific cause. Tuberculosis is the most common infectious disease associated with FUO in elderly patients. FUO often is associated with treatable conditions in the elderly. Therefore, intensive, accelerated evaluation is necessary, as the lack of physiologic reserve makes this population vulnerable to irreversible changes and functional deterioration.

  11. [Various causes of fever of unknown origin].

    PubMed

    De laco, A-C; Praz, G

    2008-10-08

    Fever of unknown origin is defined by fever lasting more than 3 weeks, with no diagnose despite a consequent work-up. 4 subgroups were determined: infectious fever, such as subacute bacterial endocarditis, tuberculosis or intra-abdominal abcess, inflammatory diseases such as temporal arteritis or adult Still's disease, neoplastic disorders, and miscellaneous causes. About one third of patients have no diagnosis at the end of the work up, and for those the prognose is usually good. There is no algorithm to know which tests to order: focused history and detailled physical status give important clues to decide about additionnal laboratories testing. An empirical treatment is justified only in case of vital risk.

  12. Fever of unknown origin due to rickettsioses.

    PubMed

    Botelho-Nevers, Elisabeth; Raoult, Didier

    2007-12-01

    Most common rickettsioses do not fill the criteria for fever of unknown origin, with fever often inferior to lasting less than 1 week. Q fever, scrub typhus, murine typhus, human monocytic ehrlichiosis, and Bartonellosis could fill these criteria, however, notably in uncommon presentations. Moreover, in patients returning from tropical areas or from geographic endemic areas for rickettsiosis, or in patients in contact with animals or ticks, theses etiologies should be kept in mind by physicians challenged to diagnose cause of fever. In this context, even without confirmation of diagnosis, treatment with doxycycline should be used.

  13. [Differential diagnosis in fever of unknown origin].

    PubMed

    Huppertz, H-I

    2006-11-01

    Fever is one of the most frequent and important symptoms in pediatrics. Most cases are caused by self-limiting viral or easily treatable bacterial infections. If after 5-7 days no cause of the ongoing fever has been found, the condition is termed fever of unknown origin, a working diagnosis which often poses a diagnostic challenge. The ultimate cause may be an infectious disease, a chronic inflammatory disorder, a malignancy, or another rare disease. The cause may also remain obscure or the fever can finally disappear. Here we elaborate the diagnostic work-up and symptomatic treatment.

  14. Optimal linear estimation under unknown nonlinear transform

    PubMed Central

    Yi, Xinyang; Wang, Zhaoran; Caramanis, Constantine; Liu, Han

    2016-01-01

    Linear regression studies the problem of estimating a model parameter β* ∈ℝp, from n observations {(yi,xi)}i=1n from linear model yi = 〈xi, β*〉 + εi. We consider a significant generalization in which the relationship between 〈xi, β*〉 and yi is noisy, quantized to a single bit, potentially nonlinear, noninvertible, as well as unknown. This model is known as the single-index model in statistics, and, among other things, it represents a significant generalization of one-bit compressed sensing. We propose a novel spectral-based estimation procedure and show that we can recover β* in settings (i.e., classes of link function f) where previous algorithms fail. In general, our algorithm requires only very mild restrictions on the (unknown) functional relationship between yi and 〈xi, β*〉. We also consider the high dimensional setting where β* is sparse, and introduce a two-stage nonconvex framework that addresses estimation challenges in high dimensional regimes where p ≫ n. For a broad class of link functions between 〈xi, β*〉 and yi, we establish minimax lower bounds that demonstrate the optimality of our estimators in both the classical and high dimensional regimes.

  15. Unknown components of the plastidial permeome

    PubMed Central

    Pick, Thea R.; Weber, Andreas P. M.

    2014-01-01

    Beyond their role in photosynthesis plastids provide a plethora of additional metabolic functions to plant cells. For example, they harbor complete biosynthetic pathways for the de novo synthesis of carotenoids, fatty acids, and amino acids. Furthermore plastids contribute important reactions to multi-compartmentalized pathways, such as photorespiration or plant hormone syntheses, and they depend on the import of essential molecules that they cannot synthesize themselves, such as ascorbic acid. This causes a high traffic of metabolites across the plastid envelope. Although it was recently shown that non-polar substrates could be exchanged between the plastid and the ER without involving transporters, various essential transport processes are mediated by highly selective but still unknown metabolite transporters. This review focuses on selected components of the plastidial permeome that are predicted to exist but that have not yet been identified as molecular entities, such as the transporters for isopentenyl diphosphate (IPP) or ascorbic acid. PMID:25191333

  16. A Physician's Nightmare: Fever of Unknown Origin

    PubMed Central

    Anwer, Farrukh

    2016-01-01

    Fever of unknown origin (FUO) remains to be a challenge despite advancement in diagnostic technologies and procedures. FUO is considered when fever presents intermittently without an explanation. It has been linked to various etiologies, which makes it difficult to diagnose. We present the case of 18-month-old female with recurrent fever, splenomegaly, abdominal pain, and constipation. The workup for her symptoms revealed wandering spleen. Wandering spleen is a result from excessive laxity or absence of splenic ligaments. The patient underwent splenectomy and was advised to continue on Senna, Miralax, and high fiber diet. Her mother reported that the fever is no longer present and there is marked improvement in her constipation and abdominal pain after splenectomy. PMID:27433363

  17. Fever of unknown origin in returning travellers.

    PubMed

    Korzeniewski, Krzysztof; Gaweł, Bartłomiej; Krankowska, Dagny; Wasilczuk, Katarzyna

    2015-01-01

    The aim of the article is to discuss issues associated with the occurrence of febrile illnesses in leisure and business travellers, with a particular emphasis on fevers of unknown origin (FUO). FUO, apart from diarrhoeas, respiratory tract infections and skin lesions, are one of the most common health problems in travellers to tropical and subtropical countries. FUO are manifestations of various diseases, typically of infectious or invasive aetiology. In one out of 3 cases, the cause of a fever in travellers returning from the hot climate zone is malaria, and therefore diagnostic tests should first aim at ruling out this specific disease entity. Other illnesses with persistent fever include dengue, enteric fever, viral hepatitis A, bacterial diarrhoeas and rickettsioses. Fever may also occur in travellers suffering from diseases of non-tropical origin, e.g. cosmopolitan respiratory tract or urinary tract infections, also, fever may coexist with other illnesses or injuries (skin rashes, bites, burns).

  18. [Fever of unknown origin in malignancies].

    PubMed

    Rieger, C T; Peterson, L; Ostermann, H

    2009-06-01

    Fever is a common symptom in patients with malignancies. On the one hand it may be an (initial) symptom of cancer, on the other hand it may occur as a side effect of chemotherapy. Often a precise cause of fever can not be established and in these cases febrile temperatures >38.3 degrees C without proof of infection or relapse/progress of tumor is defined as fever of unknown origin. Especially hematologic neoplasias are accompanied by fever. Here, neoplastic fever must be distinguished from fever following immunosuppressive chemotherapy. In the latter severe infections due to neutropenia induced by cytoreductive chemotherapy is often identified as the cause of fever. These patients display a high morbidity and mortality, especially if an empiric anti-infectious treatment is not administered in time. A meticulous diagnostic work-up is therefore necessary, and until proven otherwise, an infectious cause must be considered and empiric antibiotic treatment initiated.

  19. A Physician's Nightmare: Fever of Unknown Origin.

    PubMed

    Din, Sana; Anwer, Farrukh; Beg, Mirza

    2016-01-01

    Fever of unknown origin (FUO) remains to be a challenge despite advancement in diagnostic technologies and procedures. FUO is considered when fever presents intermittently without an explanation. It has been linked to various etiologies, which makes it difficult to diagnose. We present the case of 18-month-old female with recurrent fever, splenomegaly, abdominal pain, and constipation. The workup for her symptoms revealed wandering spleen. Wandering spleen is a result from excessive laxity or absence of splenic ligaments. The patient underwent splenectomy and was advised to continue on Senna, Miralax, and high fiber diet. Her mother reported that the fever is no longer present and there is marked improvement in her constipation and abdominal pain after splenectomy.

  20. Fever of unknown origin in aortic dissection.

    PubMed

    Yuan, S-M

    2017-05-01

    Aortic dissection is the most devastating sequela of thoracic aortic disorder. Patients with acute aortic dissection typically manifest as an acute onset of severe chest pain, but occasionally present with atypical symptoms including fever of unknown origin. A total of 50 patients from 41 articles based on a complete literature retrieval were included in this study. More patients had a fever prior to pain. The time to presentation was 40.7 ± 105.6 days, the time to diagnosis was 52.9 ± 110.1 days, and the time to surgery/intervention was 1.8 ± 5.6 days. The patients' temperature on admission was 38.2 ± 0.6 °C and the maximal temperature recorded was 38.8 ± 0.4 °C. Laboratory findings showed increased white blood cell counts, cardiac enzymes, and inflammatory biomarkers. More pronounced laboratory findings of the infectious type than the inflammatory type aortic dissection could be helpful in the differential diagnosis. Half of patients warrant aortic repair with or without valve replacement, less than half of patients were conservatively managed, and a few were interventionally treated or were being followed up. The mortality rate was 9.5 %. Physicians should always bear in mind aortic dissection when patients present with fever of unknown origin particularly in those without chest pain. Laboratory findings may offer inflammatory evidence for the diagnosis. An early diagnosis as well as subsequent treatment is indispensable for patients' outcomes.

  1. Education Through Exploration: Evaluating the Unknown

    NASA Astrophysics Data System (ADS)

    Anbar, A. D.

    2015-12-01

    Mastery of the peculiar and powerful practices of science is increasingly important for the average citizen. With the rise of the Internet, most of human knowledge is at our fingertips. As content becomes a commodity, success and survival aren't about who knows the most, but who is better able to explore the unknown, actively applying and extending knowledge through critical thinking and hypothesis-driven problem-solving. This applies to the economic livelihoods of individuals and to society at large as we grapple with climate change and other science-infused challenges. Unfortunately, science is too often taught as an encyclopedic collection of settled facts to be mastered rather than as a process of exploration that embraces curiosity, inquiry, testing, and communication to reduce uncertainty about the unknown. This problem is exacerbated by the continued prevalence of teacher-centric pedagogy, which promotes learning-from-authority and passive learning. The initial wave of massively open online courses (MOOCs) generally mimic this teaching style in virtual form. It is hypothesized that emerging digital teaching technologies can help address this challenge at Internet scale in "next generation" MOOCs and flipped classroom experiences. Interactive simulations, immersive virtual field trips, gamified elements, rapid adaptive feedback, intelligent tutoring systems, and personalized pathways, should motivate and enhance learning. Through lab-like projects and tutorials, students should be able to construct knowledge from interactive experiences, modeling the authentic practice of science while mastering complex concepts. Freed from lecturing, teaching staff should be available for direct and intense student-teacher interactions. These claims are difficult to evaluate with traditional assessment instruments, but digital technologies provide powerful new ways to evaluate student learning and learn from student behaviors. We will describe ongoing experiences with such

  2. [Recognition and identification of unknown infectious agents].

    PubMed

    Berche, P

    1994-04-01

    The recognition and the identification of previously unrecognized infectious agents require a multidisciplinary approach to specify the nosologic entity of the disease and the epidemiological data, especially the modes of transmission and the risk factors, as well as to discover the microorganism in the laboratory. In the past 20 years, significant breakthroughs have been achieved in cellular cultures (growth factors), in immunology (monoclonal antibodies), and moreover in molecular biology, which have been widely used in the field of infectious diseases. Whereas the classical methods used to grow microorganisms remain of major interest in many cases, innovating strategies have been recently designed to identify previously unknown pathogens. The genomic amplification by polymerase chain reaction (PCR) of highly conserved bacterial genes (as those coding for ribosomal RNA), from tissue biopsies for example, allow to recognize unknown bacteria. The evolutionary distance between a newly recognized pathogen and known microorganisms can be calculated through sequencing of these genes, as described for Rochalimaea henselae or Tropheryma whipplelii. The constitution of cDNA banks from infected tissues is also a novel approach allowing to clone and sequence viral genes, such as those from hepatitis C or from hepatitis E. In the near future, noteworthy improvements will be achieved to rapidly detect microorganisms with highly sensitive and specific tests using monoclonal antibodies, molecular probes (including branched DNA) and with PCR (including Q beta replicase and ligase chain reaction), and to determine the genetic diversity of microbial pathogens by new methods as pulse field gel electrophoresis or arbitrarily primed PCR. This will result in a better knowledge of the pathophysiology of infectious diseases, in a better recognition of a typical, previously unrecognized clinical expression of pathogenicity, and also in a more precise assessment of the actual impact of a

  3. A new neuro-FDS definition for indirect adaptive control of unknown nonlinear systems using a method of parameter hopping.

    PubMed

    Boutalis, Yiannis; Theodoridis, Dimitris C; Christodoulou, Manolis A

    2009-04-01

    The indirect adaptive regulation of unknown nonlinear dynamical systems is considered in this paper. The method is based on a new neuro-fuzzy dynamical system (neuro-FDS) definition, which uses the concept of adaptive fuzzy systems (AFSs) operating in conjunction with high-order neural network functions (FHONNFs). Since the plant is considered unknown, we first propose its approximation by a special form of an FDS and then the fuzzy rules are approximated by appropriate HONNFs. Thus, the identification scheme leads up to a recurrent high-order neural network (RHONN), which however takes into account the fuzzy output partitions of the initial FDS. The proposed scheme does not require a priori experts' information on the number and type of input variable membership functions making it less vulnerable to initial design assumptions. Once the system is identified around an operation point, it is regulated to zero adaptively. Weight updating laws for the involved HONNFs are provided, which guarantee that both the identification error and the system states reach zero exponentially fast, while keeping all signals in the closed loop bounded. The existence of the control signal is always assured by introducing a novel method of parameter hopping, which is incorporated in the weight updating law. Simulations illustrate the potency of the method and comparisons with conventional approaches on benchmarking systems are given. Also, the applicability of the method is tested on a direct current (dc) motor system where it is shown that by following the proposed procedure one can obtain asymptotic regulation.

  4. Parallel path planning in unknown terrains

    NASA Astrophysics Data System (ADS)

    Prassler, Erwin A.; Milios, Evangelos E.

    1991-03-01

    We present a parallel processing approach to path planning in unknown terrains which combines map-based and sensor-based techniques into a real-time capable navigation system. The method is based on massively parallel computations in a grid of simple processing elements denoted as cells. In the course of a relaxation process a potential distribution is created in the grid which exhibits a monotonous slope from a start cell to the cell corresponding to the robot''s goal position. A shortest path is determined by means of a gradient descent criterion which settles on the steepest descent in the potential distribution. Like high-level path planning algorithms our approach is capable of planning shortest paths through an arbitrarily cluttered large-scale terrain on the basis of its current internal map. Sequentially implemented its complexity is in the order of efficient classical path planning algorithms. Unlike these algorithms however the method is also highly responsive to new obstacles encountered in the terrain. By continuing the planning process during the robot''s locomotion information about previously unknown obstacles immediately affects further path planning without a need to interrupt the ongoing planning process. New obstacles cause distortions of the potential distribution which let the robot find proper detours. By ensuring a monotonous slope in the overall distribution we avoid local minimum effects which may trap a robot in the proximity of an obstacle configuration before it has reached its goal. 1 Until the recent past research on path planning in the presence of obstacles can be assigned to two major categories: map-based high-level planning approaches and sensor-based low-level conLrol approaches. In work such as 12 path planning is treated as a high-level planning task. Assuming that an (accnrae) precompiled map of the terrain is available high-level path planners provide paths which guarantee a collision-free locomotion through an arbitrary

  5. Robust control methods for nonlinear systems with uncertain dynamics and unknown control direction

    NASA Astrophysics Data System (ADS)

    Ton, Chau T.

    consideration is required in control design for systems that also include unknown bounded disturbances. To cope with these challenges, a robust continuous controller is developed using an ISMC technique, which achieves asymptotic trajectory tracking for systems with unknown bounded disturbances, while simultaneously compensating for parametric uncertainty in the input gain matrix. The ISMC design is rigorously proven to achieve asymptotic trajectory tracking for a quadrotor system and a synthetic jet actuator (SJA)-based aircraft system. In the ISMC designs, it is assumed that the signs in the uncertain input-multiplicative gain matrix (i.e., the actuator control directions) are known. A much more challenging scenario is encountered in designing controllers for classes of systems, where the uncertainty in the input gain matrix is extreme enough to result in an a priori-unknown control direction. Such a scenario can result when dealing with highly inaccurate dynamic models, unmodeled parameter variations, actuator anomalies, unknown external or internal disturbances, and/or other adversarial operating conditions. To address this challenge, a SMCbased self-recongurable control algorithm is presented, which automatically adjusts for unknown control direction via periodic switching between sliding manifolds that ultimately forces the state to a converging manifold. Rigorous mathematical analyses are presented to prove the theoretical results, and simulation results are provided to demonstrate the effectiveness of the three proposed control algorithms.

  6. [Diagnostic approach to fever of unknown origin].

    PubMed

    Bleeker-Rovers, C P; van der Meer, J W M

    2008-04-12

    Nowadays, fever of unknown origin (FUO) is generally defined as a fever higher than 38-3 degrees C lasting for a period of at least three weeks, in which no definitive diagnosis has been made after a number of obligatory tests. A diagnostic algorithm is proposed in which history taking, physical examination and the obligatory tests are the most important steps in the search for potentially diagnostic clues (PDCs). Next, factitious fever and drug fever should be ruled out. Further diagnostic procedures should be guided by the PDCs. If this does not lead to diagnosis or if there are no useful PDCs, further screening, including 18F-fluorodeoxyglucose positron emission tomography, should be performed. In 30 to 50% of the patients with FUO no diagnosis can be reached. If their clinical condition is stable, waiting to see if new PDCs develop is recommended. Most patients in whom no diagnosis can be made, have a good prognosis. Supportive treatment with NSAIDs can be helpful. Only if patients deteriorate, should other therapeutic trials be considered.

  7. Unknown Risks: Parental Hesitation about Vaccination.

    PubMed

    Blaisdell, Laura L; Gutheil, Caitlin; Hootsmans, Norbert A M; Han, Paul K J

    2016-05-01

    This qualitative study of a select sample of vaccine-hesitant parents (VHPs) explores perceived and constructed personal judgments about the risks and uncertainties associated with vaccines and vaccine-preventable diseases (VPDs) and how these subjective risk judgments influence parents' decisions about childhood vaccination. The study employed semistructured focus group interviews with 42 VHPs to elicit parents' perceptions and thought processes regarding the risks associated with vaccination and nonvaccination, the sources of these perceptions, and their approach to decision making about vaccination for their children. VHPs engage in various reasoning processes and tend to perceive risks of vaccination as greater than the risks of VPDs. At the same time, VHPs engage in other reasoning processes that lead them to perceive ambiguity in information about the harms of vaccination-citing concerns about the missing, conflicting, changing, or otherwise unreliable nature of information. VHPs' refusal of vaccination may reflect their aversion to both the risk and ambiguity they perceive to be associated with vaccination. Mitigating this vaccine hesitancy likely requires reconstructing the risks and ambiguities associated with vaccination-a challenging task that requires providing parents with meaningful evidence-based information on the known risks of vaccination versus VPDs and explicitly acknowledging the risks that remain truly unknown. © The Author(s) 2015.

  8. Fracture pain-Traveling unknown pathways.

    PubMed

    Alves, Cecília J; Neto, Estrela; Sousa, Daniela M; Leitão, Luís; Vasconcelos, Daniel M; Ribeiro-Silva, Manuel; Alencastre, Inês S; Lamghari, Meriem

    2016-04-01

    An increase of fracture incidence is expected for the next decades, mostly due to the undeniable increase of osteoporotic fractures, associated with the rapid population ageing. The rise in sports-related fractures affecting the young and active population also contributes to this increased fracture incidence, and further amplifies the economical burden of fractures. Fracture often results in severe pain, which is a primary symptom to be treated, not only to guarantee individual's wellbeing, but also because an efficient management of fracture pain is mandatory to ensure proper bone healing. Here, we review the available data on bone innervation and its response to fracture, and discuss putative mechanisms of fracture pain signaling. In addition, the common therapeutic approaches to treat fracture pain are discussed. Although there is still much to learn, research in fracture pain has allowed an initial insight into the mechanisms involved. During the inflammatory response to fracture, several mediators are released and will putatively activate and sensitize primary sensory neurons, in parallel, intense nerve sprouting that occurs in the fracture callus area is also suggested to be involved in pain signaling. The establishment of hyperalgesia and allodynia after fracture indicates the development of peripheral and central sensitization, still, the underlying mechanisms are largely unknown. A major concern during the treatment of fracture pain needs to be the preservation of proper bone healing. However, the most common therapeutic agents, NSAIDS and opiates, can cause significant side effects that include fracture repair impairment. The understanding of the mechanisms of fracture pain signaling will allow the development of mechanisms-based therapies to effectively and safely manage fracture pain.

  9. Bacterial Motility Reveals Unknown Molecular Organization

    PubMed Central

    Duchesne, Ismaël; Rainville, Simon; Galstian, Tigran

    2015-01-01

    The water solubility of lyotropic liquid crystals (LCs) makes them very attractive to study the behavior of biological microorganisms in an environment where local symmetry is broken (as often encountered in nature). Several recent studies have shown a dramatic change in the behavior of flagellated bacteria when swimming in solutions of the lyotropic LC disodium cromoglycate (DSCG). In this study, the movements of Escherichia coli bacteria in DSCG-water solutions of different concentrations are observed to improve our understanding of this phenomenon. In addition, the viscosity of DSCG aqueous solutions is measured as a function of concentration at room temperature. We also experimentally identify a previously undescribed isotropic pretransition zone where bacteria start sticking to each other and to surfaces. Simple estimations show that the unbalanced osmotic pressure induced depletion force might be responsible for this sticking phenomenon. An estimate of the bacteria propulsive force and the DSCG aggregates length (versus concentration) are calculated from the measured viscosity of the medium. All these quantities are found to undergo a strong increase in the pretransition zone, starting at a threshold concentration of 6 ± 1 wt % DSCG that is well below the known isotropic-LC transition (∼10 wt %). This study also shines light on the motility of flagellated bacteria in realistic environments, and it opens new avenues for interesting applications such as the use of motile microorganisms to probe the physical properties of their host or smart bandages that could guide bacteria out of wounds. PMID:26588572

  10. Estimation of symmetrical components and their orthogonal components under unknown frequencies and unknown biases

    NASA Astrophysics Data System (ADS)

    Chu, Zhaobi; Zhang, Rui; Chen, Bo; Li, Hua

    2017-07-01

    An algorithm to estimate symmetrical components, orthogonal components and amplitudes of each sinusoidal component in three-phase power system signal under unknown frequencies and unknown biases is presented. The algorithm consists of a signal transformation, a biased adaptive orthogonal decomposition (BAOD) and a symmetrical component estimation. The BAOD can be regarded as a combination of a low pass filter and a number of three-phase frequency estimators in parallel. The symmetrical component estimation employs addition and multiplication rather than operations of trigonometry, division and phase shift. The decomposition property and the convergence property were investigated by Lyapunov theorem, integral manifold of slow adaptation and average method. Two design parameters, bandwidth parameter and frequency adaptive gains, give different effects on the convergence property of frequency adaptation and amplitude estimation independently. Simulation results demonstrate the performance of the method.

  11. Environmental distribution and persistence of Quahog Parasite Unknown (QPX).

    PubMed

    Gast, Rebecca J; Moran, Dawn M; Audemard, Corinne; Lyons, M Maille; DeFavari, Jackie; Reece, Kimberly S; Leavitt, Dale; Smolowitz, Roxanna

    2008-09-24

    Quahog Parasite Unknown (QPX) is the cause of mass mortality events of hard clams Mercenaria mercenaria from Virginia, USA, to New Brunswick, Canada. Aquaculture areas in Massachusetts, USA, have been particularly hard hit. The parasite has been shown to be a directly infective organism, but it is unclear whether it could exist or persist outside of its clam host. We used molecular methods to examine water, sediment, seaweeds, seagrass and various invertebrates for the presence of QPX. Sites in Virginia and Massachusetts were selected based upon the incidence of QPX-induced clam die-offs, and they were monitored seasonally. QPX was detectable in almost all of our different sample types from Massachusetts, indicating that the parasite was widely distributed in the environment. Significantly more samples from Massachusetts were positive than from Virginia, and there was a seasonal pattern to the types of samples positive from Massachusetts. The data suggest that, although it may be difficult to completely eradicate QPX from the environment, it may be possible to keep the incidence of disease under control through good plot husbandry and the removal of infected and dying clams.

  12. Bacterial Motility Reveals Unknown Molecular Organization.

    PubMed

    Duchesne, Ismaël; Rainville, Simon; Galstian, Tigran

    2015-11-17

    The water solubility of lyotropic liquid crystals (LCs) makes them very attractive to study the behavior of biological microorganisms in an environment where local symmetry is broken (as often encountered in nature). Several recent studies have shown a dramatic change in the behavior of flagellated bacteria when swimming in solutions of the lyotropic LC disodium cromoglycate (DSCG). In this study, the movements of Escherichia coli bacteria in DSCG-water solutions of different concentrations are observed to improve our understanding of this phenomenon. In addition, the viscosity of DSCG aqueous solutions is measured as a function of concentration at room temperature. We also experimentally identify a previously undescribed isotropic pretransition zone where bacteria start sticking to each other and to surfaces. Simple estimations show that the unbalanced osmotic pressure induced depletion force might be responsible for this sticking phenomenon. An estimate of the bacteria propulsive force and the DSCG aggregates length (versus concentration) are calculated from the measured viscosity of the medium. All these quantities are found to undergo a strong increase in the pretransition zone, starting at a threshold concentration of 6±1 wt % DSCG that is well below the known isotropic-LC transition (∼10 wt %). This study also shines light on the motility of flagellated bacteria in realistic environments, and it opens new avenues for interesting applications such as the use of motile microorganisms to probe the physical properties of their host or smart bandages that could guide bacteria out of wounds. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  13. Design of a DNA chip for detection of unknown genetically modified organisms (GMOs).

    PubMed

    Nesvold, Håvard; Kristoffersen, Anja Bråthen; Holst-Jensen, Arne; Berdal, Knut G

    2005-05-01

    Unknown genetically modified organisms (GMOs) have not undergone a risk evaluation, and hence might pose a danger to health and environment. There are, today, no methods for detecting unknown GMOs. In this paper we propose a novel method intended as a first step in an approach for detecting unknown genetically modified (GM) material in a single plant. A model is designed where biological and combinatorial reduction rules are applied to a set of DNA chip probes containing all possible sequences of uniform length n, creating probes capable of detecting unknown GMOs. The model is theoretically tested for Arabidopsis thaliana Columbia, and the probabilities for detecting inserts and receiving false positives are assessed for various parameters for this organism. From a theoretical standpoint, the model looks very promising but should be tested further in the laboratory. The model and algorithms will be available upon request to the corresponding author.

  14. 4. Photographic copy of photograph (date unknown, original print in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. Photographic copy of photograph (date unknown, original print in the possession of the Wisconsin Veterans Museums). COTTAGES WITH DIRT ROAD IN FOREGROUND. LOCATION UNKNOWN. - Wisconsin Home for Veterans, King, Waupaca County, WI

  15. 68. Water Delivery Pipes for Menzie Cone, date unknown Historic ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    68. Water Delivery Pipes for Menzie Cone, date unknown Historic Photograph, Photographer Unknown; Collection of William Everett, Jr. (Wilkes-Barre, PA), photocopy by Joseph E.B. Elliot - Huber Coal Breaker, 101 South Main Street, Ashley, Luzerne County, PA

  16. 53. Retail Pockets, Looking West, date unknown Historic Photograph, Photogapher ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    53. Retail Pockets, Looking West, date unknown Historic Photograph, Photogapher Unknown; Collection of William Everett, Jr. (Wilkes-Barre, PA), photocopy by Joseph E.B. Elliot - Huber Coal Breaker, 101 South Main Street, Ashley, Luzerne County, PA

  17. 1. Historic American Buildings Survey Photographer Unknown. Furnished by Mrs ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Historic American Buildings Survey Photographer Unknown. Furnished by Mrs Mecia, Tombstone, Arizona. Date Unknown GENERAL VIEW MAIN CHURCH (SOUTHEAST ELEVATION). - San Xavier del Bac Mission, Mission Road, Tucson, Pima County, AZ

  18. 21. Photocopy of maesured drawing (source unknown) 6 March 1945, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. Photocopy of maesured drawing (source unknown) 6 March 1945, delineator unknown PROPOSED ADAPTIVE REUSE AS CLEMSON COLLEGE FACULTY CLUB, SITE PLAN - Woodburn, Woodburn Road, U.S. Route 76 vicinity, Pendleton, Anderson County, SC

  19. 19. Photocopy of measured drawing (source unknown) 6 March 1945, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. Photocopy of measured drawing (source unknown) 6 March 1945, delineator unknown PROPOSED ADAPTIVE REUSE AS CLEMSON COLLEGE FACULTY CLUB, SECOND FLOOR PLAN - Woodburn, Woodburn Road, U.S. Route 76 vicinity, Pendleton, Anderson County, SC

  20. 17. Photocopy of measured drawing (source unknown) 6 March 1945, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. Photocopy of measured drawing (source unknown) 6 March 1945, delineator unknown PROPOSED ADAPTIVE REUSE AS CLEMSON COLLEGE FACULTY CLUB, BASEMENT PLAN - Woodburn, Woodburn Road, U.S. Route 76 vicinity, Pendleton, Anderson County, SC

  1. 20. Photocopy of measured drawing (source unknown) 6 March 1945, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. Photocopy of measured drawing (source unknown) 6 March 1945, delineator unknown PROPOSED ADAPTIVE REUSE AS CLEMSON COLLEGE FACULTY CLUB, ATTIC PLAN - Woodburn, Woodburn Road, U.S. Route 76 vicinity, Pendleton, Anderson County, SC

  2. 18. Photocopy of measured drawing (source unknown) 6 March 1945, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. Photocopy of measured drawing (source unknown) 6 March 1945, delineator unknown PROPOSED ADAPTIVE REUSE AS CLEMSON COLLEGE FACULTY CLUB, FIRST FLOOR PLAN - Woodburn, Woodburn Road, U.S. Route 76 vicinity, Pendleton, Anderson County, SC

  3. 67. Corroded Menzie Cone with Nozzles, date unknown Historic Photograph, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    67. Corroded Menzie Cone with Nozzles, date unknown Historic Photograph, Photograph Unknown; Collection of William Everett, Jr. (Wilkes-Barre, PA), photocopy by Joseph E.B. Elliot - Huber Coal Breaker, 101 South Main Street, Ashley, Luzerne County, PA

  4. 51. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angeles, CA, Photographer, Date unknown EXTERIOR, ELEVATION DETAILS - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  5. 53. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    53. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angeles, CA, Photographer, Date unknown DETAILS OF CORRIDORS ON SECOND - TWELFTH FLOORS - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  6. 44. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    44. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angeles, CA, Photographer, Date unknown FIRST FLOOR PLAN - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  7. 47. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    47. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angleles, CA, Photographer, Date unknown WEST ELEVATION - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  8. 45. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    45. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angeles, CA, Photographer, Date unknown SECOND FLOOR PLAN - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  9. 50. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    50. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angleles, CA, Photographer, Date unknown ENTRANCE AND TYPICAL BAY ON FLOWER STREET - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  10. 49. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    49. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angeles, CA, Photographer, Date unknown SECTION THROUGH BUILDING, LOOKING EAST - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  11. 48. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    48. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angeles, CA., Photographer, Date unknown SECTION THROUGH BUILDING, LOOKING NORTH - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  12. 46. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    46. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angeles, CA, Photographer, Date unknown NORTH ELEVATION - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  13. 52. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. Photocopy of drawing (Source unknown, 1928) Rapid Blue Print Co., Los Angeles, CA, Photographer, Date unknown DETAILS OF MAIN FLOOR ELEVATOR LOBBY - Richfield Oil Building, 555 South Flower Street, Los Angeles, Los Angeles County, CA

  14. 14. Photo copy of photograph (location of original print unknown) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Photo copy of photograph (location of original print unknown) c.1932, photographer unknown Historic view of bridge - Bridge at Mouth of Rogue River, Spanning Rogue River on Oregon Coast Highway, Gold Beach, Curry County, OR

  15. Twelve previously unknown phage genera are ubiquitous in global oceans.

    PubMed

    Holmfeldt, Karin; Solonenko, Natalie; Shah, Manesh; Corrier, Kristen; Riemann, Lasse; Verberkmoes, Nathan C; Sullivan, Matthew B

    2013-07-30

    Viruses are fundamental to ecosystems ranging from oceans to humans, yet our ability to study them is bottlenecked by the lack of ecologically relevant isolates, resulting in "unknowns" dominating culture-independent surveys. Here we present genomes from 31 phages infecting multiple strains of the aquatic bacterium Cellulophaga baltica (Bacteroidetes) to provide data for an underrepresented and environmentally abundant bacterial lineage. Comparative genomics delineated 12 phage groups that (i) each represent a new genus, and (ii) represent one novel and four well-known viral families. This diversity contrasts the few well-studied marine phage systems, but parallels the diversity of phages infecting human-associated bacteria. Although all 12 Cellulophaga phages represent new genera, the podoviruses and icosahedral, nontailed ssDNA phages were exceptional, with genomes up to twice as large as those previously observed for each phage type. Structural novelty was also substantial, requiring experimental phage proteomics to identify 83% of the structural proteins. The presence of uncommon nucleotide metabolism genes in four genera likely underscores the importance of scavenging nutrient-rich molecules as previously seen for phages in marine environments. Metagenomic recruitment analyses suggest that these particular Cellulophaga phages are rare and may represent a first glimpse into the phage side of the rare biosphere. However, these analyses also revealed that these phage genera are widespread, occurring in 94% of 137 investigated metagenomes. Together, this diverse and novel collection of phages identifies a small but ubiquitous fraction of unknown marine viral diversity and provides numerous environmentally relevant phage-host systems for experimental hypothesis testing.

  16. Twelve previously unknown phage genera are ubiquitous in global oceans

    SciTech Connect

    Holmfeldt, Karin; Solonenko, Natalie; Shah, Manesh B; Corrier, Kristen L; Riemann, Lasse; Verberkmoes, Nathan C; Sullivan, Matthew B

    2013-01-01

    Viruses are fundamental to ecosystems ranging from oceans to humans, yet our ability to study them is bottlenecked by the lack of ecologically relevant isolates, resulting in unknowns dominating culture-independent surveys. Here we present genomes from 31 phages infecting multiple strains of the aquatic bacterium Cellulophaga baltica (Bacteroidetes) to provide data for an underrepresented and environmentally abundant bacterial lineage. Comparative genomics delineated 12 phage groups that (i) each represent a new genus, and (ii) represent one novel and four wellknown viral families. This diversity contrasts the few well-studied marine phage systems, but parallels the diversity of phages infecting human-associated bacteria. Although all 12 Cellulophaga phages represent new genera, the podoviruses and icosahedral, nontailed ssDNA phages were exceptional, with genomes up to twice as large as those previously observed for each phage type. Structural novelty was also substantial, requiring experimental phage proteomics to identify 83% of the structural proteins. The presence of uncommon nucleotide metabolism genes in four genera likely underscores the importance of scavenging nutrient-rich molecules as previously seen for phages in marine environments. Metagenomic recruitment analyses suggest that these particular Cellulophaga phages are rare and may represent a first glimpse into the phage side of the rare biosphere. However, these analyses also revealed that these phage genera are widespread, occurring in 94% of 137 investigated metagenomes. Together, this diverse and novel collection of phages identifies a small but ubiquitous fraction of unknown marine viral diversity and provides numerous environmentally relevant phage host systems for experimental hypothesis testing.

  17. Structured illumination microscopy with unknown patterns and a statistical prior

    PubMed Central

    Yeh, Li-Hao; Tian, Lei; Waller, Laura

    2017-01-01

    Structured illumination microscopy (SIM) improves resolution by down-modulating high-frequency information of an object to fit within the passband of the optical system. Generally, the reconstruction process requires prior knowledge of the illumination patterns, which implies a well-calibrated and aberration-free system. Here, we propose a new algorithmic self-calibration strategy for SIM that does not need to know the exact patterns a priori, but only their covariance. The algorithm, termed PE-SIMS, includes a pattern-estimation (PE) step requiring the uniformity of the sum of the illumination patterns and a SIM reconstruction procedure using a statistical prior (SIMS). Additionally, we perform a pixel reassignment process (SIMS-PR) to enhance the reconstruction quality. We achieve 2× better resolution than a conventional widefield microscope, while remaining insensitive to aberration-induced pattern distortion and robust against parameter tuning. PMID:28270977

  18. The elements of nursing ... all but unknown.

    PubMed Central

    Norman, S.

    1998-01-01

    In summing up, I have explored briefly some notions on the elements of nursing through the theme of partnership with the public and with others involved in health care. These notions, which are by no means exclusive, have centred around five main areas; Firstly, the unique personal characteristics demanded by the closeness of sustained contact with patients and clients; Secondly, the primacy of the patient's and the public's needs in defining nursing or any other health care profession; Thirdly, the need for nursing both individually and organisationally to look outwards and engage with the wider public and their changing attitudes towards the professions; Fourthly, the unique skill of 'creating community', working with, co-ordinating and leading teams across disciplines in the interests of the patient and the challenge that true effectiveness of multi-disciplinary working presents for both education and practice; and Fifthly, the importance of reflective practice throughout the working life of nurses as a means of better meeting patients' needs. How nursing retains this focus whilst adapting to a constantly and rapidly shifting health and social care environment, will largely determine how nursing endures as a profession. If the example set by Florence Elliott and the many innovations and developments at the Royal Victoria Hospital are anything to go by, the people of Northern Ireland, nurses in Northern Ireland and health care generally in Northern Ireland, can look forward to another 200 years of healthy partnership. Images p98-a PMID:9807965

  19. Control of a flexible-link robotic arm manipulating an unknown dynamic payload

    NASA Astrophysics Data System (ADS)

    Alder, Lawrence John

    1993-12-01

    When light-weight space-based robots, such as the space shuttle's RMS (remote manipulator system), manipulate massive payloads such as satellites, significant structural bending is induced in the links of the robot. In addition, space-based robots will often manipulate payloads that are not rigid bodies: for example, satellites may contain fuel or have flexible appendages. This dissertation contributes new basic technology that will enable flexible-link manipulators to perform precise end-point control of payloads while simultaneously controlling the unknown internal dynamics of the payload. The approach taken here combines high-performance control with an innovative identification algorithm. In addition, to facilitate the development of controllers, a numerically efficient procedure to merge payload and arm dynamic models is presented. First, controllers incorporating end-point feedback with a known payload are made robust to high-frequency modelling errors, sensor noise, and sensor bias using frequency-weighted linear quadratic Gaussian design methods. Using end-point position measurements as the primary sensor, the robot is then capable of actively damping the internal payload dynamics an order of magnitude faster than the natural damping rate--if it knows the payload parameter. However, with this type of controller small parameter variations in the payload can lead to poor performance or instability. This research has therefore also developed an identification algorithm that updates the end-point controller parameters; this enables the system to achieve high performance when the payload dynamics are not known a priori. By using a nominal control law, the identification problem can be reduced to detecting and identifying eigenvalues of a closed system. To identify these eigenvalues, a generic algorithm capable of determining the eigenvalues of a system in real time has been developed: even the order of the system need not be known in advance. With this approach

  20. Previously unknown virus infects marine diatom.

    PubMed

    Nagasaki, Keizo; Tomaru, Yuji; Takao, Yoshitake; Nishida, Kensho; Shirai, Yoko; Suzuki, Hidekazu; Nagumo, Tamotsu

    2005-07-01

    Diatoms are a major phytoplankton group that play important roles in maintaining oxygen levels in the atmosphere and sustaining the primary nutritional production of the aquatic environment. Among diatoms, the genus Chaetoceros is one of the most abundant and widespread. Temperature, climate, salinity, nutrients, and predators were regarded as important factors controlling the abundance and population dynamics of diatoms. Here we show that a viral infection can occur in the genus Chaetoceros and should therefore be considered as a potential mortality source. Chaetoceros salsugineum nuclear inclusion virus (CsNIV) is a 38-nm icosahedral virus that replicates within the nucleus of C. salsugineum. The latent period was estimated to be between 12 and 24 h, with a burst size of 325 infectious units per host cell. CsNIV has a genome structure unlike that of other viruses that have been described. It consists of a single molecule of covalently closed circular single-stranded DNA (ssDNA; 6,005 nucleotides), as well as a segment of linear ssDNA (997 nucleotides). The linear segment is complementary to a portion of the closed circle creating a partially double-stranded genome. Sequence analysis reveals a low but significant similarity to the replicase of circoviruses that have a covalently closed circular ssDNA genome. This new host-virus system will be useful for investigating the ecological relationships between bloom-forming diatoms and other viruses in the marine system. Our study supports the view that, given the diversity and abundance of plankton, the ocean is a treasury of undiscovered viruses.

  1. Previously Unknown Virus Infects Marine Diatom

    PubMed Central

    Nagasaki, Keizo; Tomaru, Yuji; Takao, Yoshitake; Nishida, Kensho; Shirai, Yoko; Suzuki, Hidekazu; Nagumo, Tamotsu

    2005-01-01

    Diatoms are a major phytoplankton group that play important roles in maintaining oxygen levels in the atmosphere and sustaining the primary nutritional production of the aquatic environment. Among diatoms, the genus Chaetoceros is one of the most abundant and widespread. Temperature, climate, salinity, nutrients, and predators were regarded as important factors controlling the abundance and population dynamics of diatoms. Here we show that a viral infection can occur in the genus Chaetoceros and should therefore be considered as a potential mortality source. Chaetoceros salsugineum nuclear inclusion virus (CsNIV) is a 38-nm icosahedral virus that replicates within the nucleus of C. salsugineum. The latent period was estimated to be between 12 and 24 h, with a burst size of 325 infectious units per host cell. CsNIV has a genome structure unlike that of other viruses that have been described. It consists of a single molecule of covalently closed circular single-stranded DNA (ssDNA; 6,005 nucleotides), as well as a segment of linear ssDNA (997 nucleotides). The linear segment is complementary to a portion of the closed circle creating a partially double-stranded genome. Sequence analysis reveals a low but significant similarity to the replicase of circoviruses that have a covalently closed circular ssDNA genome. This new host-virus system will be useful for investigating the ecological relationships between bloom-forming diatoms and other viruses in the marine system. Our study supports the view that, given the diversity and abundance of plankton, the ocean is a treasury of undiscovered viruses. PMID:16000758

  2. Differential diagnosis of fever of unknown origin in children.

    PubMed

    Majeed, H A

    2000-09-01

    Fever of unknown origin in children follows two main clinical patterns, namely fever of unknown origin and chronic episodic fever of unknown origin. Fever of unknown origin is characterized by daily fever persisting for more than 3 weeks. The main causes are infectious, rheumatologic disorders, and malignancy. Chronic episodic fever of unknown origin is characterized by fever lasting for a few days to a few weeks, followed by a fever-free interval and a sense of well-being. The main causes are familial Mediterranean fever, the hyper-immunoglobulin D syndrome, familial Hibernian fever, Behcet disease, the syndrome of periodic fever, aphthous stomatitis, pharyngitis and adenitis, and cyclic neutropenia.

  3. Control design for the SISO system with the unknown order and the unknown relative degree.

    PubMed

    Zhao, Chunzhe; Li, Donghai

    2014-07-01

    For the uncertain system whose order, relative degree and parameters are unknown in the control design, new research is still in need on the parameter tuning and close-loop stability. During the last 10 years, much progress is made in the application and theory research of the active disturbance rejection control (ADRC) for the uncertain system. In this study, the necessary and sufficient conditions are established for building the ADRC for the minimum-phase system and the open-loop stable system when the plant parameters, orders and relative degrees are unknown, the corresponding ideal dynamics are analyzed, and the theoretical results are verified by the simulations. Considering the wide application and the long history of the PID/PI controller, a method is given to design ADRC quickly based on the existing (generalized or conventional) PID/PI controller. A plenty of simulations are made to illustrate this PID/PI-based design method and the corresponding close-loop performances. The simulation examples include the minimum/nonminimum-phase plants, the stable/integrating plants, the high/low-order plant, and the plants with time delays. Such plants are from a wider scope than the theoretical result, and representative of many kinds of the industrial processes. That leads to a new way to simplify the ADRC design via absorbing the engineering experience in designing the PID/PI controller.

  4. Nitrogen cycle in microbial mats: completely unknown?

    NASA Astrophysics Data System (ADS)

    Coban, O.; Bebout, B.

    2015-12-01

    Microbial mats are thought to have originated around 3.7 billion years ago, most likely in the areas around submarine hydrothermal vents, which supplied a source of energy in the form of reduced chemical species from the Earth's interior. Active hydrothermal vents are also believed to exist on Jupiter's moon Europa, Saturn's moon Enceladus, and on Mars, earlier in that planet's history. Microbial mats have been an important force in the maintenance of Earth's ecosystems and the first photosynthesis was also originated there. Microbial mats are believed to exhibit most, if not all, biogeochemical processes that exist in aquatic ecosystems, due to the presence of different physiological groups of microorganisms therein. While most microbially mediated biogeochemical transformations have been shown to occur within microbial mats, the nitrogen cycle in the microbial mats has received very little study in spite of the fact that nitrogen usually limits growth in marine environments. We will present the first results in the determination of a complete nitrogen budget for a photosynthetic microbial mat. Both in situ sources and sinks of nitrogen in photosynthetic microbial mats are being measured using stable isotope techniques. Our work has a particular focus on recently described, but poorly understood, processes, e.g., anammox and dissimilatory nitrate reduction, and an emphasis on understanding the role that nitrogen cycling may play in generating biogenic nitrogen isotopic signatures and biomarker molecules. Measurements of environmental controls on nitrogen cycling should offer insight into the nature of co-evolution of these microbial communities and their planets of origin. Identifying the spatial (microscale) as well as temporal (diel and seasonal) distribution of nitrogen transformations, e.g., rates of nitrification and denitrification, within mats, particularly with respect to the distribution of photosynthetically-produced oxygen, is anticipated. The results

  5. Fitting a linear-linear piecewise growth mixture model with unknown knots: A comparison of two common approaches to inference.

    PubMed

    Kohli, Nidhi; Hughes, John; Wang, Chun; Zopluoglu, Cengiz; Davison, Mark L

    2015-06-01

    A linear-linear piecewise growth mixture model (PGMM) is appropriate for analyzing segmented (disjointed) change in individual behavior over time, where the data come from a mixture of 2 or more latent classes, and the underlying growth trajectories in the different segments of the developmental process within each latent class are linear. A PGMM allows the knot (change point), the time of transition from 1 phase (segment) to another, to be estimated (when it is not known a priori) along with the other model parameters. To assist researchers in deciding which estimation method is most advantageous for analyzing this kind of mixture data, the current research compares 2 popular approaches to inference for PGMMs: maximum likelihood (ML) via an expectation-maximization (EM) algorithm, and Markov chain Monte Carlo (MCMC) for Bayesian inference. Monte Carlo simulations were carried out to investigate and compare the ability of the 2 approaches to recover the true parameters in linear-linear PGMMs with unknown knots. The results show that MCMC for Bayesian inference outperformed ML via EM in nearly every simulation scenario. Real data examples are also presented, and the corresponding computer codes for model fitting are provided in the Appendix to aid practitioners who wish to apply this class of models.

  6. How to know unknown fungi: the role of a herbarium.

    PubMed

    Brock, Patrick M; Döring, Heidi; Bidartondo, Martin I

    2009-01-01

    The development of a universal approach to the identification of fungi from the environment is impeded by the limited number and narrow phylogenetic range of the named internal transcribed spacer DNA sequences available on GenBank. The goal here was to assess the potential impact of systematic DNA sequencing from a fungal herbarium collection. DNA sequences were generated from a diverse set of 279 specimens deposited at the fungal herbarium of the Royal Botanic Gardens at Kew (UK) and bioinformatic analyses were used to study their overlap with the public database. It is estimated that c. 70% of the herbarium taxonomic diversity is not yet represented in GenBank and that a further c. 10% of our sequences match solely to 'environmental samples' or fungi otherwise unidentified. Here it is shown that the unsampled diversity residing in fungal herbaria can substantially enlarge the coverage of GenBank's fully identified sequence pool to ameliorate the problem of environmental unknowns and to aid in the detection of truly novel fungi by molecular data.

  7. Previously unknown class of metalorganic compounds revealed in meteorites

    PubMed Central

    Ruf, Alexander; Kanawati, Basem; Hertkorn, Norbert; Yin, Qing-Zhu; Moritz, Franco; Harir, Mourad; Lucio, Marianna; Michalke, Bernhard; Wimpenny, Joshua; Shilobreeva, Svetlana; Bronsky, Basil; Saraykin, Vladimir; Gabelica, Zelimir; Gougeon, Régis D.; Quirico, Eric; Ralew, Stefan; Jakubowski, Tomasz; Haack, Henning; Gonsior, Michael; Jenniskens, Peter; Hinman, Nancy W.; Schmitt-Kopplin, Philippe

    2017-01-01

    The rich diversity and complexity of organic matter found in meteorites is rapidly expanding our knowledge and understanding of extreme environments from which the early solar system emerged and evolved. Here, we report the discovery of a hitherto unknown chemical class, dihydroxymagnesium carboxylates [(OH)2MgO2CR]−, in meteoritic soluble organic matter. High collision energies, which are required for fragmentation, suggest substantial thermal stability of these Mg-metalorganics (CHOMg compounds). This was corroborated by their higher abundance in thermally processed meteorites. CHOMg compounds were found to be present in a set of 61 meteorites of diverse petrological classes. The appearance of this CHOMg chemical class extends the previously investigated, diverse set of CHNOS molecules. A connection between the evolution of organic compounds and minerals is made, as Mg released from minerals gets trapped into organic compounds. These CHOMg metalorganic compounds and their relation to thermal processing in meteorites might shed new light on our understanding of carbon speciation at a molecular level in meteorite parent bodies. PMID:28242686

  8. Chronic kidney disease of unknown etiology in Sri Lanka

    PubMed Central

    2016-01-01

    Introduction In the last two decades, chronic kidney disease of unknown etiology (CKDu) has emerged as a significant contributor to the burden of chronic kidney disease (CKD) in rural Sri Lanka. It is characterized by the absence of identified causes for CKD. The prevalence of CKDu is 15.1–22.9% in some Sri Lankan districts, and previous research has found an association with farming occupations. Methods A systematic literature review in Pubmed, Embase, Scopus, and Lilacs databases identified 46 eligible peer-reviewed articles and one conference abstract. Results Geographical mapping indicates a relationship between CKDu and agricultural irrigation water sources. Health mapping studies, human biological studies, and environment-based studies have explored possible causative agents. Most studies focused on likely causative agents related to agricultural practices, geographical distribution based on the prevalence and incidence of CKDu, and contaminants identified in drinking water. Nonetheless, the link between agrochemicals or heavy metals and CKDu remains to be established. No definitive cause for CKDu has been identified. Discussion Evidence to date suggests that the disease is related to one or more environmental agents, however pinpointing a definite cause for CKDu is challenging. It is plausible that CKDu is multifactorial. No specific guidelines or recommendations exist for treatment of CKDu, and standard management protocols for CKD apply. Changes in agricultural practices, provision of safe drinking water, and occupational safety precautions are recommended by the World Health Organization. PMID:27399161

  9. Chronic kidney disease of unknown etiology in Sri Lanka.

    PubMed

    Rajapakse, Senaka; Shivanthan, Mitrakrishnan Chrishan; Selvarajah, Mathu

    2016-07-01

    In the last two decades, chronic kidney disease of unknown etiology (CKDu) has emerged as a significant contributor to the burden of chronic kidney disease (CKD) in rural Sri Lanka. It is characterized by the absence of identified causes for CKD. The prevalence of CKDu is 15.1-22.9% in some Sri Lankan districts, and previous research has found an association with farming occupations. A systematic literature review in Pubmed, Embase, Scopus, and Lilacs databases identified 46 eligible peer-reviewed articles and one conference abstract. Geographical mapping indicates a relationship between CKDu and agricultural irrigation water sources. Health mapping studies, human biological studies, and environment-based studies have explored possible causative agents. Most studies focused on likely causative agents related to agricultural practices, geographical distribution based on the prevalence and incidence of CKDu, and contaminants identified in drinking water. Nonetheless, the link between agrochemicals or heavy metals and CKDu remains to be established. No definitive cause for CKDu has been identified. Evidence to date suggests that the disease is related to one or more environmental agents, however pinpointing a definite cause for CKDu is challenging. It is plausible that CKDu is multifactorial. No specific guidelines or recommendations exist for treatment of CKDu, and standard management protocols for CKD apply. Changes in agricultural practices, provision of safe drinking water, and occupational safety precautions are recommended by the World Health Organization.

  10. Previously unknown class of metalorganic compounds revealed in meteorites.

    PubMed

    Ruf, Alexander; Kanawati, Basem; Hertkorn, Norbert; Yin, Qing-Zhu; Moritz, Franco; Harir, Mourad; Lucio, Marianna; Michalke, Bernhard; Wimpenny, Joshua; Shilobreeva, Svetlana; Bronsky, Basil; Saraykin, Vladimir; Gabelica, Zelimir; Gougeon, Régis D; Quirico, Eric; Ralew, Stefan; Jakubowski, Tomasz; Haack, Henning; Gonsior, Michael; Jenniskens, Peter; Hinman, Nancy W; Schmitt-Kopplin, Philippe

    2017-03-14

    The rich diversity and complexity of organic matter found in meteorites is rapidly expanding our knowledge and understanding of extreme environments from which the early solar system emerged and evolved. Here, we report the discovery of a hitherto unknown chemical class, dihydroxymagnesium carboxylates [(OH)2MgO2CR](-), in meteoritic soluble organic matter. High collision energies, which are required for fragmentation, suggest substantial thermal stability of these Mg-metalorganics (CHOMg compounds). This was corroborated by their higher abundance in thermally processed meteorites. CHOMg compounds were found to be present in a set of 61 meteorites of diverse petrological classes. The appearance of this CHOMg chemical class extends the previously investigated, diverse set of CHNOS molecules. A connection between the evolution of organic compounds and minerals is made, as Mg released from minerals gets trapped into organic compounds. These CHOMg metalorganic compounds and their relation to thermal processing in meteorites might shed new light on our understanding of carbon speciation at a molecular level in meteorite parent bodies.

  11. 56. photographer unknown 14 October 1935 CONCRETE BLOCKS OF SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. photographer unknown 14 October 1935 CONCRETE BLOCKS OF SOUTH HALF OF SPILLWAY SHOWING STEEL REINFORCING OF BAFFLES. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  12. 57. photographer unknown 30 October 1935 PIERS RISING FROM CONCRETE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    57. photographer unknown 30 October 1935 PIERS RISING FROM CONCRETE DECK. BAFFLES IN VARIOUS STAGES OF CONSTRUCTION. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  13. 88. photographer unknown undated DOWNSTREAM VIEW OF CONSTRUCTION ON NORTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    88. photographer unknown undated DOWNSTREAM VIEW OF CONSTRUCTION ON NORTH HALF OF MAIN DAM, COFFERDAM IN BACKGROUND. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  14. 74. photographer unknown 10 February 1936 DOWNSTREAM SIDE OF SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    74. photographer unknown 10 February 1936 DOWNSTREAM SIDE OF SOUTH HALF OF MAIN DAM. BRADFORD ISLAND IN BACKGROUND. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  15. 34. photographer unknown undated PARTIALLY CONSTRUCTED CRIB NO. 9. NOTE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. photographer unknown undated PARTIALLY CONSTRUCTED CRIB NO. 9. NOTE CONTOURING TO FIT IRREGULARITIES OF RIVER BOTTOM. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  16. 16. Historic photograph, photographer unknown, 1943. VIEW OF BRIDGE UNDER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. Historic photograph, photographer unknown, 1943. VIEW OF BRIDGE UNDER CONSTRUCTION, LOOKING WEST. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  17. Photocopy of photograph (source and date unknown) FRONT ELEVATION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (source and date unknown) FRONT ELEVATION - Merion Friends Meeting House, 615 Montgomery Avenue (changed from Montgomery Avenue & Meetinghouse Lane), Narberth, Montgomery County, PA

  18. Emerging role of drug interaction studies in drug development: the good, the bad, and the unknown.

    PubMed

    Alfaro, C L

    2001-01-01

    Significant scientific advancements in the last decade have armed researchers with tools to assess drug metabolism and the effects of drugs on metabolic pathways; however, most of this research has focused on cytochrome P450 isozymes. Early delineation of this information aids in the prediction of potential drug-drug interactions, which may ultimately determine whether a compound is pursued in the drug development process. The recent withdrawals of medications such as terfenadine, astemizole, cisapride, and mibefradil from the market demonstrate the relevance of this a priori approach--the risk of drug interactions was largely unrecognized prior to their approval by the Food and Drug Administration (FDA). Drug interaction studies for new drug applications (NDAs) field between 1987 and 1991 were largely in vivo studies with potential coadministered drugs, whereas for NDAs field between 1992 and 1997, the majority of studies involved metabolic mechanisms and in vitro methodology. Despite current limitations in the extrapolation of in vitro drug metabolism data to the in vivo environment, in vitro studies remain the mainstay of initial evaluations in this area primarily because of the high throughput nature of these investigations and the reduced cost compared with in vivo studies. The FDA has published several guidance documents in the area of drug metabolism and drug interaction studies in drug development with suggestions for in vitro as well as in vivo approaches to these investigations. Current and future research will likely focus on in vitro models for cytochrome P450 induction, Phase II metabolism, and drug transporters, and include validation and extrapolation of these approaches in vivo.

  19. Considering unknown unknowns: reconstruction of nonconfoundable causal relations in biological networks.

    PubMed

    Sadeh, Mohammad J; Moffa, Giusi; Spang, Rainer

    2013-11-01

    Our current understanding of cellular networks is rather incomplete. We over look important but so far unknown genes and mechanisms in the pathways. Moreover, we often only have a partial account of the molecular interactions and modifications of the known players. When analyzing the cell, we look through narrow windows leaving potentially important events in blind spots. Network reconstruction is naturally confined to what we have observed. Little is known on how the incompleteness of our observations confounds our interpretation of the available data. Here we ask which features of a network can be confounded by incomplete observations and which cannot. In the context of nested effects models, we show that in the presence of missing observations or hidden factors a reliable reconstruction of the full network is not feasible. Nevertheless, we can show that certain characteristics of signaling networks like the existence of cross-talk between certain branches of the network can be inferred in a nonconfoundable way. We derive a test for inferring such nonconfoundable characteristics of signaling networks. Next, we introduce a new data structure to represent partially reconstructed signaling networks. Finally, we evaluate our method both on simulated data and in the context of a study on early stem cell differentiation in mice.

  20. Considering Unknown Unknowns: Reconstruction of Nonconfoundable Causal Relations in Biological Networks

    PubMed Central

    Moffa, Giusi; Spang, Rainer

    2013-01-01

    Abstract Our current understanding of cellular networks is rather incomplete. We over look important but so far unknown genes and mechanisms in the pathways. Moreover, we often only have a partial account of the molecular interactions and modifications of the known players. When analyzing the cell, we look through narrow windows leaving potentially important events in blind spots. Network reconstruction is naturally confined to what we have observed. Little is known on how the incompleteness of our observations confounds our interpretation of the available data. Here we ask which features of a network can be confounded by incomplete observations and which cannot. In the context of nested effects models, we show that in the presence of missing observations or hidden factors a reliable reconstruction of the full network is not feasible. Nevertheless, we can show that certain characteristics of signaling networks like the existence of cross-talk between certain branches of the network can be inferred in a nonconfoundable way. We derive a test for inferring such nonconfoundable characteristics of signaling networks. Next, we introduce a new data structure to represent partially reconstructed signaling networks. Finally, we evaluate our method both on simulated data and in the context of a study on early stem cell differentiation in mice. PMID:24195708

  1. Students' Conscious Unknowns about Artefacts and Natural Objects

    ERIC Educational Resources Information Center

    Vaz-Rebelo, Piedade; Fernandes, Paula; Morgado, Julia; Monteiro, António; Otero, José

    2016-01-01

    This study attempts to characterise what 7th- and 12th-grade students believe they do not know about artefacts and natural objects, as well as the dependence of what is unknown on a knowledge of these objects. The students were asked to make explicit through questioning what they did not know about a sample of objects. The unknowns generated were…

  2. 16 CFR 303.14 - Products containing unknown fibers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Products containing unknown fibers. 303.14... RULES AND REGULATIONS UNDER THE TEXTILE FIBER PRODUCTS IDENTIFICATION ACT § 303.14 Products containing unknown fibers. (a) Where a textile fiber product is made from miscellaneous scraps, rags, odd...

  3. 16 CFR 303.14 - Products containing unknown fibers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Products containing unknown fibers. 303.14... RULES AND REGULATIONS UNDER THE TEXTILE FIBER PRODUCTS IDENTIFICATION ACT § 303.14 Products containing unknown fibers. (a) Where a textile fiber product is made from miscellaneous scraps, rags, odd...

  4. Students' Conscious Unknowns about Artefacts and Natural Objects

    ERIC Educational Resources Information Center

    Vaz-Rebelo, Piedade; Fernandes, Paula; Morgado, Julia; Monteiro, António; Otero, José

    2016-01-01

    This study attempts to characterise what 7th- and 12th-grade students believe they do not know about artefacts and natural objects, as well as the dependence of what is unknown on a knowledge of these objects. The students were asked to make explicit through questioning what they did not know about a sample of objects. The unknowns generated were…

  5. 16 CFR 303.14 - Products containing unknown fibers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Products containing unknown fibers. 303.14... RULES AND REGULATIONS UNDER THE TEXTILE FIBER PRODUCTS IDENTIFICATION ACT § 303.14 Products containing unknown fibers. (a) Where a textile fiber product is made from miscellaneous scraps, rags, odd lots...

  6. 16 CFR 303.14 - Products containing unknown fibers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Products containing unknown fibers. 303.14... RULES AND REGULATIONS UNDER THE TEXTILE FIBER PRODUCTS IDENTIFICATION ACT § 303.14 Products containing unknown fibers. (a) Where a textile fiber product is made from miscellaneous scraps, rags, odd lots...

  7. 16 CFR 303.14 - Products containing unknown fibers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Products containing unknown fibers. 303.14... RULES AND REGULATIONS UNDER THE TEXTILE FIBER PRODUCTS IDENTIFICATION ACT § 303.14 Products containing unknown fibers. (a) Where a textile fiber product is made from miscellaneous scraps, rags, odd lots...

  8. 37 CFR 381.9 - Unknown copyright owners.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2013-07-01 2013-07-01 false Unknown copyright owners. 381.9 Section 381.9 Patents, Trademarks, and Copyrights COPYRIGHT ROYALTY BOARD, LIBRARY OF CONGRESS... EDUCATIONAL BROADCASTING § 381.9 Unknown copyright owners. If PBS and its stations, NPR and its stations,...

  9. 37 CFR 253.9 - Unknown copyright owners.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Unknown copyright owners. 253.9 Section 253.9 Patents, Trademarks, and Copyrights COPYRIGHT OFFICE, LIBRARY OF CONGRESS COPYRIGHT... NONCOMMERCIAL EDUCATIONAL BROADCASTING § 253.9 Unknown copyright owners. If PBS and its stations, NPR and...

  10. 37 CFR 260.7 - Unknown copyright owners.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Unknown copyright owners. 260.7 Section 260.7 Patents, Trademarks, and Copyrights COPYRIGHT OFFICE, LIBRARY OF CONGRESS COPYRIGHT... TRANSMISSIONS OF SOUND RECORDINGS AND MAKING OF EPHEMERAL PHONORECORDS § 260.7 Unknown copyright owners. If...

  11. 37 CFR 381.9 - Unknown copyright owners.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Unknown copyright owners. 381.9 Section 381.9 Patents, Trademarks, and Copyrights COPYRIGHT ROYALTY BOARD, LIBRARY OF CONGRESS... EDUCATIONAL BROADCASTING § 381.9 Unknown copyright owners. If PBS and its stations, NPR and its stations,...

  12. 37 CFR 382.7 - Unknown copyright owners.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Unknown copyright owners. 382.7 Section 382.7 Patents, Trademarks, and Copyrights COPYRIGHT ROYALTY BOARD, LIBRARY OF CONGRESS... SATELLITE DIGITAL AUDIO RADIO SERVICES Preexisting Subscription Services § 382.7 Unknown copyright...

  13. 37 CFR 260.7 - Unknown copyright owners.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2013-07-01 2013-07-01 false Unknown copyright owners. 260.7 Section 260.7 Patents, Trademarks, and Copyrights COPYRIGHT OFFICE, LIBRARY OF CONGRESS COPYRIGHT... TRANSMISSIONS OF SOUND RECORDINGS AND MAKING OF EPHEMERAL PHONORECORDS § 260.7 Unknown copyright owners. If...

  14. 37 CFR 381.9 - Unknown copyright owners.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2014-07-01 2014-07-01 false Unknown copyright owners. 381.9 Section 381.9 Patents, Trademarks, and Copyrights COPYRIGHT ROYALTY BOARD, LIBRARY OF CONGRESS... EDUCATIONAL BROADCASTING § 381.9 Unknown copyright owners. If PBS and its stations, NPR and its stations,...

  15. 37 CFR 260.7 - Unknown copyright owners.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Unknown copyright owners. 260.7 Section 260.7 Patents, Trademarks, and Copyrights COPYRIGHT OFFICE, LIBRARY OF CONGRESS COPYRIGHT... TRANSMISSIONS OF SOUND RECORDINGS AND MAKING OF EPHEMERAL PHONORECORDS § 260.7 Unknown copyright owners. If...

  16. 37 CFR 253.9 - Unknown copyright owners.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2013-07-01 2013-07-01 false Unknown copyright owners. 253.9 Section 253.9 Patents, Trademarks, and Copyrights COPYRIGHT OFFICE, LIBRARY OF CONGRESS COPYRIGHT... NONCOMMERCIAL EDUCATIONAL BROADCASTING § 253.9 Unknown copyright owners. If PBS and its stations, NPR and...

  17. 37 CFR 253.9 - Unknown copyright owners.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Unknown copyright owners. 253.9 Section 253.9 Patents, Trademarks, and Copyrights COPYRIGHT OFFICE, LIBRARY OF CONGRESS COPYRIGHT... NONCOMMERCIAL EDUCATIONAL BROADCASTING § 253.9 Unknown copyright owners. If PBS and its stations, NPR and...

  18. 37 CFR 381.9 - Unknown copyright owners.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Unknown copyright owners. 381.9 Section 381.9 Patents, Trademarks, and Copyrights COPYRIGHT ROYALTY BOARD, LIBRARY OF CONGRESS... EDUCATIONAL BROADCASTING § 381.9 Unknown copyright owners. If PBS and its stations, NPR and its stations,...

  19. 37 CFR 260.7 - Unknown copyright owners.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Unknown copyright owners. 260.7 Section 260.7 Patents, Trademarks, and Copyrights COPYRIGHT OFFICE, LIBRARY OF CONGRESS COPYRIGHT... TRANSMISSIONS OF SOUND RECORDINGS AND MAKING OF EPHEMERAL PHONORECORDS § 260.7 Unknown copyright owners. If...

  20. 48. Northwest Side of Breaker, from Culm Bank, date unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    48. Northwest Side of Breaker, from Culm Bank, date unknown Historic Photograph, Photographer Unknown; Collection of William Everett, Jr. (Wilkes-Barre,PA), photocopy by Joseph E.B. Elliot - Huber Coal Breaker, 101 South Main Street, Ashley, Luzerne County, PA

  1. 15. Photo copy of photograph (location of original print unknown) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Photo copy of photograph (location of original print unknown) c.1932, photographer unknown Historic view of cartouche detail at center of arch - Bridge at Mouth of Rogue River, Spanning Rogue River on Oregon Coast Highway, Gold Beach, Curry County, OR

  2. 15. Photocopy of photograph (Courtesy of Lawrence D. Thornton) Unknown, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Photocopy of photograph (Courtesy of Lawrence D. Thornton) Unknown, Photographer, Date Unknown PERPSECTIVE VIEW (WEST) OF ENTRANCE HALL SHOWING FRONT DOOR WITH FANLIGHT AND ORIGINAL SIDELIGHTS - Hamilton Grange, (Moved From) 237 West 141 Street to 141st Street & Amsterdam, New York County, NY

  3. Bayesian methods for characterizing unknown parameters of material models

    SciTech Connect

    Emery, J. M.; Grigoriu, M. D.; Field Jr., R. V.

    2016-02-04

    A Bayesian framework is developed for characterizing the unknown parameters of probabilistic models for material properties. In this framework, the unknown parameters are viewed as random and described by their posterior distributions obtained from prior information and measurements of quantities of interest that are observable and depend on the unknown parameters. The proposed Bayesian method is applied to characterize an unknown spatial correlation of the conductivity field in the definition of a stochastic transport equation and to solve this equation by Monte Carlo simulation and stochastic reduced order models (SROMs). As a result, the Bayesian method is also employed to characterize unknown parameters of material properties for laser welds from measurements of peak forces sustained by these welds.

  4. Bayesian methods for characterizing unknown parameters of material models

    DOE PAGES

    Emery, J. M.; Grigoriu, M. D.; Field Jr., R. V.

    2016-02-04

    A Bayesian framework is developed for characterizing the unknown parameters of probabilistic models for material properties. In this framework, the unknown parameters are viewed as random and described by their posterior distributions obtained from prior information and measurements of quantities of interest that are observable and depend on the unknown parameters. The proposed Bayesian method is applied to characterize an unknown spatial correlation of the conductivity field in the definition of a stochastic transport equation and to solve this equation by Monte Carlo simulation and stochastic reduced order models (SROMs). As a result, the Bayesian method is also employed tomore » characterize unknown parameters of material properties for laser welds from measurements of peak forces sustained by these welds.« less

  5. Twelve previously unknown phage genera are ubiquitous in global oceans

    PubMed Central

    Holmfeldt, Karin; Solonenko, Natalie; Shah, Manesh; Corrier, Kristen; Riemann, Lasse; VerBerkmoes, Nathan C.; Sullivan, Matthew B.

    2013-01-01

    Viruses are fundamental to ecosystems ranging from oceans to humans, yet our ability to study them is bottlenecked by the lack of ecologically relevant isolates, resulting in “unknowns” dominating culture-independent surveys. Here we present genomes from 31 phages infecting multiple strains of the aquatic bacterium Cellulophaga baltica (Bacteroidetes) to provide data for an underrepresented and environmentally abundant bacterial lineage. Comparative genomics delineated 12 phage groups that (i) each represent a new genus, and (ii) represent one novel and four well-known viral families. This diversity contrasts the few well-studied marine phage systems, but parallels the diversity of phages infecting human-associated bacteria. Although all 12 Cellulophaga phages represent new genera, the podoviruses and icosahedral, nontailed ssDNA phages were exceptional, with genomes up to twice as large as those previously observed for each phage type. Structural novelty was also substantial, requiring experimental phage proteomics to identify 83% of the structural proteins. The presence of uncommon nucleotide metabolism genes in four genera likely underscores the importance of scavenging nutrient-rich molecules as previously seen for phages in marine environments. Metagenomic recruitment analyses suggest that these particular Cellulophaga phages are rare and may represent a first glimpse into the phage side of the rare biosphere. However, these analyses also revealed that these phage genera are widespread, occurring in 94% of 137 investigated metagenomes. Together, this diverse and novel collection of phages identifies a small but ubiquitous fraction of unknown marine viral diversity and provides numerous environmentally relevant phage–host systems for experimental hypothesis testing. PMID:23858439

  6. All optical measurement of an unknown wideband microwave frequency

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Priye, V.; Raj Singh, R.

    2016-12-01

    A novel all optical measurement scheme is proposed to measure wideband microwave frequencies up to 30 GHz. The proposed method is based on a four-wave mixing (FWM) approach in a semiconductor optical amplifier (SOA) of both even order side-bands generated by an unknown microwave frequency modulating an optical carrier. The optical power of a generated FWM signal depends on frequency spacing between extracted side-bands. A mathematical relation is established between FWM power and frequency of an unknown signal. A calibration curve is drawn based on the mathematical relation which predicts the unknown frequency from power withdrawn after FWM.

  7. Adaptive interferometric null testing for unknown freeform optics metrology.

    PubMed

    Huang, Lei; Choi, Heejoo; Zhao, Wenchuan; Graves, Logan R; Kim, Dae Wook

    2016-12-01

    We report an adaptive interferometric null testing method for overcoming the dynamic range limitations of conventional null testing approaches during unknown freeform optics metrology or optics manufacturing processes that require not-yet-completed surface measurements to guide the next fabrication process. In the presented adaptive method, a deformable mirror functions as an adaptable null component for an unknown optical surface. The optimal deformable mirror's shape is determined by the stochastic parallel gradient descent algorithm and controlled by a deflectometry system. An adaptive interferometric null testing setup was constructed, and its metrology data successfully demonstrated superb adaptive capability in measuring an unknown surface.

  8. 18. Photocopy of photograph (photographer unknown, July 1932, original print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. Photocopy of photograph (photographer unknown, July 1932, original print in possession of National Park Service, Petrified Forest National Park), BRIDGE IMMEDIATELY AFTER COMPLETION. - Rio Puerco Bridge, Mainline Road, spanning Rio Puerco, Holbrook, Navajo County, AZ

  9. 17. Photocopy of photograph (photographer unknown, March 1932, original print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. Photocopy of photograph (photographer unknown, March 1932, original print in possession of National Park Service, Petrified Forest National Park), BRIDGE UNDER CONSTRUCTION. - Rio Puerco Bridge, Mainline Road, spanning Rio Puerco, Holbrook, Navajo County, AZ

  10. 25. Photocopy of photograph (Source unknown, c. 19231925) EXTERIOR, CLOSEUP ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. Photocopy of photograph (Source unknown, c. 1923-1925) EXTERIOR, CLOSE-UP OF SOUTH FRONT OF MISSION AFTER RESTORATION, C. 1923-1925 - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

  11. 29. photographer unknown 27 August 1935 GRAVEL AND SAND HOPPERS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. photographer unknown 27 August 1935 GRAVEL AND SAND HOPPERS IN CONCRETE PLANT. - Bonneville Project, Columbia River, 1 mile Northeast of Exit 40, off Interstate 84, Bonneville, Multnomah County, OR

  12. A Method for Finding Unknown Signals Using Reinforcement FFT Differencing

    SciTech Connect

    Charles R. Tolle; John W. James

    2009-12-01

    This note addresses a simple yet powerful method of discovering the spectral character of an unknown but intermittent signal buried in a background made up of a distribution of other signals. Knowledge of when the unknown signal is present and when it is not, along with samples of the combined signal when the unknown signal is present and when it is not are all that is necessary for this method. The method is based on reinforcing Fast Fourier Transform (FFT) power spectra when the signal of interest occurs and subtracting spectra when it does not. Several examples are presented. This method could be used to discover spectral components of unknown chemical species within spectral analysis instruments such as Mass Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography. In addition, this method can be used to isolate device loading signatures on power transmission lines.

  13. 1. Site of Mormon Flat Dam looking upstream. Photographer unknown, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Site of Mormon Flat Dam looking upstream. Photographer unknown, 1923. Source: Salt River Project. - Mormon Flat Dam, On Salt River, Eastern Maricopa County, east of Phoenix, Phoenix, Maricopa County, AZ

  14. 76. photographer unknown undated STRUCTURAL STEEL TRUSSES FOR DOWNSTREAM THIRD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    76. photographer unknown undated STRUCTURAL STEEL TRUSSES FOR DOWNSTREAM THIRD STEP COFFERDAM IN PLACE. TWO PADS FOR THIS COFFERDAM ARE LAYING ON THE BAFFLES TO THE LEFT OF THE TRUSSES. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  15. 63. photographer unknown 21 November 1935 BAFFLES AND PIERS FOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    63. photographer unknown 21 November 1935 BAFFLES AND PIERS FOR SOUTH HALF OF MAIN DAM IN VARIOUS STAGES OF CONSTRUCTION. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  16. 27. Photographic copy of undated photo; Photographer unknown; Original owned ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. Photographic copy of undated photo; Photographer unknown; Original owned by Waterloo Community Development Board, Waterloo, Iowa; SPLITTING CATTLE CARCASSES WITH RECIPROCATING SAW - Rath Packing Company, Beef Killing Building, Sycamore Street between Elm & Eighteenth Streets, Waterloo, Black Hawk County, IA

  17. 356. Delineator Unknown March 1946 STATE OF CALIFORNIA; DEPARTMENT OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    356. Delineator Unknown March 1946 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; GENERAL DATA; PLAT III - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  18. View of an unknown industrial building in the Dolphin Jute ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of an unknown industrial building in the Dolphin Jute Mill Complex, looking southwest. Note Garret Mountain at upper left and historic Dexter-Lambert smokestack. - Dolphin Manufacturing Company, Spruce & Barbour Streets, Paterson, Passaic County, NJ

  19. Genetics Experts Unite to I.D. Unknown Katrina Victims

    MedlinePlus

    ... Current Issue Past Issues Research News From NIH Genetics Experts Unite to I.D. Unknown Katrina Victims ... in the recent Advances in molecular biology and genetics," says team member Stephen Sherry, Ph.D., of ...

  20. 28. photographer unknown undated SIDE VIEW OF PARTIALLY CONSTRUCTED CRIB ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. photographer unknown undated SIDE VIEW OF PARTIALLY CONSTRUCTED CRIB NO. 13. NOTE CONTOURING TO FIT IRREGULARITIES OF RIVER BOTTOM. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  1. 46. photographer unknown 26 June 1935 MODEL OF SOUTH HALF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    46. photographer unknown 26 June 1935 MODEL OF SOUTH HALF MAIN SPILLWAY DAM, LOOKING DOWNSTREAM WITH CENTER CRIBS REMOVED. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  2. 52. photographer unknown 9 October 1935 CURING CONCRETE BLOCKS FOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. photographer unknown 9 October 1935 CURING CONCRETE BLOCKS FOR BASE OF SOUTH HALF OF SPILLWAY DAM. INSPECTION TUNNEL FORM IN BACKGROUND. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  3. 27. photographer unknown undated DREDGING OVERBURDEN FROM CRIB EXCAVATION AREAS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. photographer unknown undated DREDGING OVERBURDEN FROM CRIB EXCAVATION AREAS IN MAIN CHANNEL FOR FIRST STEP COFFERDAM. BRADFORD ISLAND IN BACKGROUND. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  4. 68. photographer unknown 15 January 1936 DOWNSTREAM SIDE OF SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    68. photographer unknown 15 January 1936 DOWNSTREAM SIDE OF SOUTH HALF OF MAIN DAM. COFFERDAM AND RIVER IN BACKGROUND. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  5. 45. photographer unknown 26 June 1935 MODEL OF SOUTH HALF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    45. photographer unknown 26 June 1935 MODEL OF SOUTH HALF OF MAIN SPILLWAY DAM, LOOKING UPSTREAM WITH CRIBS IN PLACE. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  6. 91. photographer unknown undated TOP OF SPILLWAY DAM PIERS WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    91. photographer unknown undated TOP OF SPILLWAY DAM PIERS WITH ASSEMBLY OF DAM GATES UNDERWAY. WASHINGTON SHORE WING WALL IN BACKGROUND. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  7. 32. photographer unknown undated PARTIALLY CONSTRUCTED CRIB NO. 11 ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. photographer unknown undated PARTIALLY CONSTRUCTED CRIB NO. 11 ON WAYS JUST PRIOR TO LAUNCHING. CRIB SHOWS WET SIDE SHEATHING, BLOCKING, FILLER BLOCKS, AND VERTICALS. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  8. 61. photographer unknown November 1935 STEEL REINFORCING FOR APRON, SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    61. photographer unknown November 1935 STEEL REINFORCING FOR APRON, SOUTH HALF OF MAIN DAM. OUTLINE OF SPILLWAY PAINTED ON INSIDE OF COFFERDAM. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  9. 47. photographer unknown 26 June 1935 MODEL OF SOUTH HALF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    47. photographer unknown 26 June 1935 MODEL OF SOUTH HALF OF MAIN SPILLWAY DAM, LOOKING DOWNSTREAM WITH CRIBS IN PLACE. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  10. 1. Historic American Buildings Survey, Copy, Photographer unknown 1900 (a) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Historic American Buildings Survey, Copy, Photographer unknown 1900 (a) Old Photo showing Kilns about 1900 (from original print found at site) - Charcoal Kilns, Valley Road, Pelham, Hampshire County, MA

  11. 35. Photocopy of drawing (from Library of Congress) Artist unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. Photocopy of drawing (from Library of Congress) Artist unknown 1891 SOUTH FRONT FROM THE SOUTHWEST - Patent Office Building, Bounded by Seventh, Ninth, F & G Streets, Northwest, Washington, District of Columbia, DC

  12. System for identifying known materials within a mixture of unknowns

    DOEpatents

    Wagner, John S.

    1999-01-01

    One or both of two methods and systems are used to determine concentration of a known material in an unknown mixture on the basis of the measured interaction of electromagnetic waves upon the mixture. One technique is to utilize a multivariate analysis patch technique to develop a library of optimized patches of spectral signatures of known materials containing only those pixels most descriptive of the known materials by an evolutionary algorithm. Identity and concentration of the known materials within the unknown mixture is then determined by minimizing the residuals between the measurements from the library of optimized patches and the measurements from the same pixels from the unknown mixture. Another technique is to train a neural network by the genetic algorithm to determine the identity and concentration of known materials in the unknown mixture. The two techniques may be combined into an expert system providing cross checks for accuracy.

  13. Method for identifying known materials within a mixture of unknowns

    DOEpatents

    Wagner, John S.

    2000-01-01

    One or both of two methods and systems are used to determine concentration of a known material in an unknown mixture on the basis of the measured interaction of electromagnetic waves upon the mixture. One technique is to utilize a multivariate analysis patch technique to develop a library of optimized patches of spectral signatures of known materials containing only those pixels most descriptive of the known materials by an evolutionary algorithm. Identity and concentration of the known materials within the unknown mixture is then determined by minimizing the residuals between the measurements from the library of optimized patches and the measurements from the same pixels from the unknown mixture. Another technique is to train a neural network by the genetic algorithm to determine the identity and concentration of known materials in the unknown mixture. The two techniques may be combined into an expert system providing cross checks for accuracy.

  14. 54. Date unknown. "No. 38. View of stringers and middle ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. Date unknown. "No. 38. View of stringers and middle pier, Wheeler Creek Bridge, Pinnacles Road, mile two. Taken from under bridge, looking up." - Crater Lake National Park Roads, Klamath Falls, Klamath County, OR

  15. 43. Photocopy of photograph, photographer unknown, ca January 1929 (original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    43. Photocopy of photograph, photographer unknown, ca January 1929 (original print located at Arizona Department of Transportation, Phoenix AZ). COMPLETED BRIDGE. - Navajo Bridge, Spanning Colorado River at U.S. Highway 89 Alternate, Page, Coconino County, AZ

  16. 6. Photographic copy of photograph (date unknown, original print in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Photographic copy of photograph (date unknown, original print in the possession of the Wisconsin Veterans Museums). COTTAGES, INCLUDING 'J.P. McPHERSON POST NO. 27 CAFE GENEVA'. - Wisconsin Home for Veterans, King, Waupaca County, WI

  17. 26. photographer unknown 19 August 1935 SOUNDING BARGE USED TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. photographer unknown 19 August 1935 SOUNDING BARGE USED TO DETERMINE RIVER-BOTTOM CONTOURS. - Bonneville Project, Columbia River, 1 mile Northeast of Exit 40, off Interstate 84, Bonneville, Multnomah County, OR

  18. 43. Photographer unknown September 1967 VISITOR INFORMATION KIOSK, LOCATED NEAR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    43. Photographer unknown September 1967 VISITOR INFORMATION KIOSK, LOCATED NEAR THE POWDER MILL ROAD INTERCHANGE. (NPS/NCR (cn) 9995-C) - Baltimore-Washington Parkway, Greenbelt, Prince George's County, MD

  19. 22. Photographic copy of photograph, circa 1928, photographer unknown (original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. Photographic copy of photograph, circa 1928, photographer unknown (original in Rundell Library, Rochester, New York) AUDITORIUM AND STAGE DECORATED FOR POLITICAL CONVENTION, VIEW FROM BALCONY LOOKING SOUTHWEST - New York State Arsenal, 75 Woodbury Boulevard, Rochester, Monroe County, NY

  20. [Fever without focus and fever of unknown origin in childhood].

    PubMed

    Ritz, Nicole

    2013-01-30

    Fever is one of the most common presenting symptoms in children. In the majority of cases the underlying cause is easily diagnosed and if necessary a treatment initiated. In case of absent localising symptoms and signs (fever without a focus) investigations rapidly need to be undertaken in particular in newborns and infants. Persisting daily fever for more than two weeks are called fever of unknown origin. Diagnosis of etiology of fever of unknown origin is challenging. In approximately half of the cases an infectious cause is found; inflammatory and mailgnant diseases account for 5 to 10% of the cases. Despite a systematic and interdisciplinary approach the etiology remains unknown in up to a quarter of cases. This review discusses differential diagnoses, suggested investigations and treatment for fever without a focus and fever of unknown origin.

  1. 53. photographer unknown October 1935 WORK ON SOUTH HALF SPILLWAY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    53. photographer unknown October 1935 WORK ON SOUTH HALF SPILLWAY SHOWING REINFORCING STEEL AND PLACING CONCRETE. COFFERDAM IN BACKGROUND. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  2. 62. photographer unknown undated ERECTING FORMS, PLACING REINFORCING STEEL, AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    62. photographer unknown undated ERECTING FORMS, PLACING REINFORCING STEEL, AND CONCRETING DRAFT PIER OF POWERHOUSE. - Bonneville Project, Powerhouse No.1, Spanning Bradford Slough, from Bradford Island, Bonneville, Multnomah County, OR

  3. Photographic copy of photograph, photographer unknown, 1908 (original print located ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 1908 (original print located at National Archives and Records Administration, Denver, Colorado). "HANDLING ROCK - BOISE RIVER DIVERSION DAM." - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  4. Photographic copy of photograph, photographer unknown, 1908 (original print located ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 1908 (original print located at National Archives and Records Administration, Denver, Colorado). "CONSTRUCTION - BOISE RIVER DIVERSION DAM." - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  5. Photographic copy of photograph, photographer unknown, 1908 (original print located ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 1908 (original print located at National Archives and Records Administration, Denver, Colorado). "CONSTRUCTION - BOISE RIVER DAM" WITH FOOT BRIDGE IN FOREGROUND - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  6. Photographic copy of photograph, photographer unknown, 23 May 1912 (original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 23 May 1912 (original print located at National Archives and Records Administration, Denver, Colorado). "SWITCHBOARD IN POWER PLANT AT DIVERSION DAM" - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  7. Photographic copy of photograph, photographer unknown, 17 April 1912 (original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 17 April 1912 (original print located at National Archives and Records Administration, Denver, Colorado). "POWER PLANT CONSTRUCTION AT DIVERSION DAM" - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  8. Photographic copy of photograph, photographer unknown, 20 March 1913 (original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 20 March 1913 (original print located at National Archives and Records Administration, Denver, Colorado). "ROLLING DAM AT DIVERSION DAM" - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  9. Photographic copy of photograph, photographer unknown, 20 March 1913 (original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 20 March 1913 (original print located at National Archives and Records Administration, Denver, Colorado). "ROLLING DAM IN SPILLWAY AT DIVERSION DAM" - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  10. Photographic copy of photograph, photographer unknown, 20 March 1912 (original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 20 March 1912 (original print located at National Archives and Records Administration, Denver, Colorado). "INTERIOR OF POWER HOUSE BEFORE COMPLETION" - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  11. Photographic copy of photograph, photographer unknown, 20 March 1912 (original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 20 March 1912 (original print located at National Archives and Records Administration, Denver, Colorado). "DIVERSION WORKS AND POWER HOUSE CONSTRUCTION" - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  12. Photographic copy of photograph, photographer unknown, 23 May 1912 (original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photographic copy of photograph, photographer unknown, 23 May 1912 (original print located at National Archives and Records Administration, Denver, Colorado). "GENERATORS IN POWER PLANT; DIVERSION DAM" - Boise Project, Boise River Diversion Dam, Across Boise River, Boise, Ada County, ID

  13. 47. Photocopy of postcard (Pentran file), photographer unknown. Hampton's Old ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    47. Photocopy of postcard (Pentran file), photographer unknown. Hampton's Old Point Comfort electric trolley in 1921. - Newport News & Old Point Railway & Electric Company, Trolley Barn & Administration Building, 3400 Victoria Boulevard, Hampton, Hampton, VA

  14. 51. BOILER ROOM. SMALL BOILER ON LEFT OF UNKNOWN MANUFACTURE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. BOILER ROOM. SMALL BOILER ON LEFT OF UNKNOWN MANUFACTURE, WITH INDUCTION MOTORS. HARTLEY BOILER, MONTGOMERY, ALABAMA, ON RIGHT. - Prattville Manufacturing Company, Number One, 242 South Court Street, Prattville, Autauga County, AL

  15. 26. photographer unknown 29 December 1937 FLOATING MOORING BIT INSTALLED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. photographer unknown 29 December 1937 FLOATING MOORING BIT INSTALLED IN LOCK SIDEWALL. - Bonneville Project, Navigation Lock No. 1, Oregon shore of Columbia River near first Powerhouse, Bonneville, Multnomah County, OR

  16. 39. Photocopy of photograph (Pentran file), photographer and date unknown. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    39. Photocopy of photograph (Pentran file), photographer and date unknown. Bus garage to left now demolished. VIEW SOUTH - Newport News & Old Point Railway & Electric Company, Trolley Barn & Administration Building, 3400 Victoria Boulevard, Hampton, Hampton, VA

  17. Floating Crane YD82 general view. Date taken unknown. Taken ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Floating Crane YD-82 - general view. Date taken unknown. Taken by Pearl Harbor photographer. Crane Division Collection - U.S. Naval Base, Pearl Harbor, Exterior Cranes, Waterfront Crane Track System, Pearl City, Honolulu County, HI

  18. 35. Photocopy of photograph. Photographer unknown, 1904 NEWLY COMPLETED OFFICE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. Photocopy of photograph. Photographer unknown, 1904 NEWLY COMPLETED OFFICE, SUBSTATION, CAR BARN. VIEW TO NORTHEAST. - Milwaukee Light, Heat & Traction Company, 8336 West Lapham Street, West Allis, Milwaukee County, WI

  19. 37. Photocopy of photograph. Photographer unknown, 1904 FRONT FACADE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. Photocopy of photograph. Photographer unknown, 1904 FRONT FACADE AND EAST SIDE OF NEWLY COMPLETED BUILDING. VIEW TO WEST-NORTHWEST. - Milwaukee Light, Heat & Traction Company, 8336 West Lapham Street, West Allis, Milwaukee County, WI

  20. 36. Photocopy of photograph. Photographer unknown, 1904 FRONT FACADE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    36. Photocopy of photograph. Photographer unknown, 1904 FRONT FACADE AND WEST SIDE OF NEWLY COMPLETED BUILDING. VIEW TO EAST-NORTHEAST. - Milwaukee Light, Heat & Traction Company, 8336 West Lapham Street, West Allis, Milwaukee County, WI

  1. 32. Historic photograph, photographer unknown, c. 1943. VIEW OF HORSESHOE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. Historic photograph, photographer unknown, c. 1943. VIEW OF HORSESHOE DAM SITE BRIDGE, LOOKING NORTH, SHOWING BRIDGE SPANNING THE VERDE RIVER BEFORE DAM WAS BUILT. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  2. 40. Historic photograph, photographer unknown, c. 1954. VIEW OF SHEARING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    40. Historic photograph, photographer unknown, c. 1954. VIEW OF SHEARING SHEEP IN SHED NEAR WEST END OF THE BRIDGE. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  3. 35. Historic photograph, photographer unknown, c. 1941. VIEW OF HORSESHOE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. Historic photograph, photographer unknown, c. 1941. VIEW OF HORSESHOE DAM SITE BRIDGE, SHOWING WALKWAY WITH CHARLES WILLIS (WITH HAT) AND FAMILY. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  4. 18. Historic photograph, photographer unknown, 1943. VIEW OF BRIDGE, LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. Historic photograph, photographer unknown, 1943. VIEW OF BRIDGE, LOOKING EAST. EAST TOWER ON SKYLINE HAS NOT BEEN REINFORCED WITH CONCRETE. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  5. 29. Historic photographer, photographer unknown, c. 1944. VIEW OF BRIDGE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. Historic photographer, photographer unknown, c. 1944. VIEW OF BRIDGE, LOOKING EAST FROM TOP OF WEST TOWER. SHEEP CROSSING BRIDGE. NOTE SWAY CABLES. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  6. 41. Historic photograph, photographer unknown, c. 1954. VIEW OF LOADING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Historic photograph, photographer unknown, c. 1954. VIEW OF LOADING SACKS OF FLEECES ONTO TRUCK AT JUNCTION OF SEVEN SPRINGS ROAD AND TANGLE CREEK ROAD. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  7. 38. Historic photograph, photographer unknown, c. 1944. VIEW SHOWING BURROS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    38. Historic photograph, photographer unknown, c. 1944. VIEW SHOWING BURROS (OR MULES) CROSSING BRIDGE, LOOKING NORTHEAST. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  8. 37. Historic photograph, photographer unknown, c. 1942. PHOTOGRAPH OF B. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. Historic photograph, photographer unknown, c. 1942. PHOTOGRAPH OF B. L. 'LES' SMITH, SON OF GEORGE W. SMITH, REPAIRING HORSESHOE DAM SITE BRIDGE - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  9. 39. Historic photograph, photographer unknown, c. 1944. VIEW SHOWING SHEEP ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    39. Historic photograph, photographer unknown, c. 1944. VIEW SHOWING SHEEP CROSSING BRIDGE, LOOKING WEST FROM CORRAL AT EAST APPROACH TO WALKWAY. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  10. 34. Historic photograph, photographer unknown, October 10, 1944. VIEW SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. Historic photograph, photographer unknown, October 10, 1944. VIEW SHOWING HORSESHOE DAM UNDER CONSTRUCTION, LOOKING WEST. ONLY THE BRIDGE TOWERS REMAIN. - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  11. 2. Photocopy of photograph (from Reading Co. Archives) Photographer unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Photocopy of photograph (from Reading Co. Archives) Photographer unknown ca. 1937 NORTHEAST FRONT AND SOUTHEAST SIDE - Philadelphia & Reading Railroad, Terminal Station, 1115-1141 Market Street, Philadelphia, Philadelphia County, PA

  12. 44. Reinforcement construction to Pleasant Dam. Photographer unknown, 1935. Source: ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    44. Reinforcement construction to Pleasant Dam. Photographer unknown, 1935. Source: Huber Collection, University of California, Berkeley, Water Resources Library. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  13. 41. Upstream end of emergency spillway excavation. Photographer unknown, 1929. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Upstream end of emergency spillway excavation. Photographer unknown, 1929. Source: Arizona Department of Water Resources (ADWR). - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  14. The Unknown Computer Viruses Detection Based on Similarity

    NASA Astrophysics Data System (ADS)

    Liu, Zhongda; Nakaya, Naoshi; Koui, Yuuji

    New computer viruses are continually being generated and they cause damage all over the world. In general, current anti-virus software detects viruses by matching a pattern based on the signature; thus, unknown viruses without any signature cannot be detected. Although there are some static analysis technologies that do not depend on signatures, virus writers often use code obfuscation techniques, which make it difficult to execute a code analysis. As is generally known, unknown viruses and known viruses share a common feature. In this paper we propose a new static analysis technology that can circumvent code obfuscation to extract the common feature and detect unknown viruses based on similarity. The results of evaluation experiments demonstrated that this technique is able to detect unknown viruses without false positives.

  15. 32. photographer unknown undated AGGREGATE PLANT SHOWING MAIN BELT CONVEYOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. photographer unknown undated AGGREGATE PLANT SHOWING MAIN BELT CONVEYOR UNITS AND STORAGE UNIT. - Bonneville Project, Columbia River, 1 mile Northeast of Exit 40, off Interstate 84, Bonneville, Multnomah County, OR

  16. 11. Photocopy of photograph (from St. Paul's Church) Photographer unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Photocopy of photograph (from St. Paul's Church) Photographer unknown 1886 'EPISCOPAL CHURCH, CORNER OF 1ST AND J ST. BENICIA' WEST AND SOUTH SIDES - St. Paul's Episcopal Church, 120 East J Street, Benicia, Solano County, CA

  17. 73. photographer unknown 9 January 1936 TOP OF DRAFT TUBE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    73. photographer unknown 9 January 1936 TOP OF DRAFT TUBE LINER AND SPEED RING PIERS. - Bonneville Project, Powerhouse No.1, Spanning Bradford Slough, from Bradford Island, Bonneville, Multnomah County, OR

  18. 1. PHOTOCOPY OF HISTORIC DRAWING OF SHIP SECTION, UNKNOWN DELINEATOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. PHOTOCOPY OF HISTORIC DRAWING OF SHIP SECTION, UNKNOWN DELINEATOR AND DATE, SOURCE: BISHOP MUSEUM, HONOLULU, HI. - Ship "Falls of Clyde", Hawaii Maritime Center,Pier 7, Honolulu, Honolulu County, HI

  19. 14. Photocopy, photographer unknown, c. 1933 INTERIOR OF LIVING ROOM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Photocopy, photographer unknown, c. 1933 INTERIOR OF LIVING ROOM LOOKING WEST-SOUTHWEST - White Deer Lake Camp, Living Room Cabin, Cyrus H. McCormick Experimental Forest, Champion, Marquette County, MI

  20. 10. Photocopy, photographer unknown, c. 1933 CHIMNEY AND LIVING ROOM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Photocopy, photographer unknown, c. 1933 CHIMNEY AND LIVING ROOM CABINS VIEWED FROM THE LAKE - White Deer Lake Camp, Living Room Cabin, Cyrus H. McCormick Experimental Forest, Champion, Marquette County, MI

  1. 30. Upstream face of construction effort. Photographer unknown, January 29, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. Upstream face of construction effort. Photographer unknown, January 29, 1927. Source: Fritz Seifritz. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  2. 13. Photocopy of color photograph (Photographer unknown, 1974) INTERIOR OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. Photocopy of color photograph (Photographer unknown, 1974) INTERIOR OF SACRISTY LOOKING NORTHEAST, SHOWING FURRING AND METAL LATH PUT IN DURING 1974 RESTORATION - Church of the Holy Cross, State Route 261, Stateburg, Sumter County, SC

  3. 15. photographer unknown undated JACKHAMMERS DRILLING AT WEST END OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. photographer unknown undated JACKHAMMERS DRILLING AT WEST END OF BOAT ROCK, SITE LATER ABANDONED. - Bonneville Project, Columbia River, 1 mile Northeast of Exit 40, off Interstate 84, Bonneville, Multnomah County, OR

  4. 12. Photocopy of lithograph (source unknown) The Armor Lithograph Company, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. Photocopy of lithograph (source unknown) The Armor Lithograph Company, Ltd., Pittsburgh, Pennsylvania, ca. 1888 COURTHOUSE AND JAIL, FROM THE WEST - Allegheny County Courthouse & Jail, 436 Grant Street (Courthouse), 420 Ross Street (Jail), Pittsburgh, Allegheny County, PA

  5. 3. Photocopy of photograph, original photographer unknown, ca. 1921; VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Photocopy of photograph, original photographer unknown, ca. 1921; VIEW LOOKING SOUTHWEST, APPARENTLY AFTER A HURRICANE (NOTE ROOF DAMAGE) - Superintendent of Lighthouses Dwelling, Punta Puntilla, San Juan, San Juan Municipio, PR

  6. 2. Photocopy of photograph, original photographer unknown, ca. 1921; VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Photocopy of photograph, original photographer unknown, ca. 1921; VIEW LOOKING NORTHWEST, APPARENTLY AFTER A HURRICANE (NOTE ROOF DAMAGE) - Superintendent of Lighthouses Dwelling, Punta Puntilla, San Juan, San Juan Municipio, PR

  7. Optimal programmable unambiguous discriminator between two unknown latitudinal states

    NASA Astrophysics Data System (ADS)

    Sunian, XiaoBing; Li, YuWei; Zhou, Tao

    2016-10-01

    Two unknown states can be unambiguously distinguished by a universal programmable discriminator, which has been widely discussed in previous works and the optimal solution has also been obtained. In this paper, we investigate the programmable unambiguous discriminator between two unknown "latitudinal" states, which lie in a subspace of the total state space. By equivalence of unknown pure states to known average mixed states, the optimal solution for this problem is systematically derived, and the analytical success probabilities for the optimal unambiguous discrimination are obtained. It is beyond one's expectation that the optimal setting for the programmable unambiguous discrimination between two unknown "latitudinal" states is the same as that for the universal ones. The results in this work can be used for the realization of the programmable discriminator in laboratory.

  8. 22. Photocopy of drawing Delineator unknown, ca. 1931 Wright Studio, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. Photocopy of drawing Delineator unknown, ca. 1931 Wright Studio, photographer View from Kellogg Blvd. - St. Paul City Hall & Ramsey County Courthouse, 15 West Kellogg Boulevard, Saint Paul, Ramsey County, MN

  9. 48 CFR 47.305-5 - Destination unknown.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-5 Destination unknown. (a)(1) When... shipping weights, the solicitation shall state that subsequent shipments shall be made in carloads or...

  10. 48 CFR 47.305-5 - Destination unknown.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-5 Destination unknown. (a)(1) When... shipping weights, the solicitation shall state that subsequent shipments shall be made in carloads or...

  11. 3. Photocopy of photograph (location of original unknown) Mary Mather, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Photocopy of photograph (location of original unknown) Mary Mather, photographer, ca. 1920 PARTIAL EAST ELEVATION, OBSCURED BY FOLIAGE - Bagatelle Plantation, East River Road (moved to Iberville Parish), Donaldsonville, Ascension Parish, LA

  12. 2. Photocopy of photograph (location of original unknown) Mary Mather, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Photocopy of photograph (location of original unknown) Mary Mather, photographer, ca. 1920 GENERAL VIEW OF WEST (LEFT) AND SOUTH (RIGHT) FACADES, TAKEN FROM LEVEE - Bagatelle Plantation, East River Road (moved to Iberville Parish), Donaldsonville, Ascension Parish, LA

  13. 3. VIEW OF BORING MILL IN OPERATION, operator unknown (note ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW OF BORING MILL IN OPERATION, operator unknown (note console in background). - Juniata Shops, Erecting Shop & Machine Shop, East of Fourth Avenue, between Fourth & Fifth Streets, Altoona, Blair County, PA

  14. 4. VIEW OF BORING MILL IN OPERATION, operator unknown (note ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW OF BORING MILL IN OPERATION, operator unknown (note console in background). - Juniata Shops, Erecting Shop & Machine Shop, East of Fourth Avenue, between Fourth & Fifth Streets, Altoona, Blair County, PA

  15. System for identifying known materials within a mixture of unknowns

    DOEpatents

    Wagner, J.S.

    1999-07-20

    One or both of two methods and systems are used to determine concentration of a known material in an unknown mixture on the basis of the measured interaction of electromagnetic waves upon the mixture. One technique is to utilize a multivariate analysis patch technique to develop a library of optimized patches of spectral signatures of known materials containing only those pixels most descriptive of the known materials by an evolutionary algorithm. Identity and concentration of the known materials within the unknown mixture is then determined by minimizing the residuals between the measurements from the library of optimized patches and the measurements from the same pixels from the unknown mixture. Another technique is to train a neural network by the genetic algorithm to determine the identity and concentration of known materials in the unknown mixture. The two techniques may be combined into an expert system providing cross checks for accuracy. 37 figs.

  16. [Diagnostic approach of recurrent fevers of unknown origin in adults].

    PubMed

    Zenone, T

    2015-07-01

    Recurrent fever of unknown origin is probably the most difficult to diagnose subtype of fever of unknown origin. It represents between 18 and 42% of the cases in large series of patients with fever of unknown origin. The limited literature data do not allow one to construct a diagnostic algorithm. However, the diagnostic strategy is different from classic fever of unknown origin. The spectrum of causative disorders is different from continuous fever with less infections and tumors. Among systemic inflammatory diseases, adult-onset Still's disease is the most common cause. More than 50% of the cases remain unexplained. Hereditary recurrent fevers, the prototype of autoinflammatory diseases, are now more easily discuss in a young adult.

  17. 15. Photocopy, photographer unknown, c. 194041 SOUTH ELEVATION WITH ORIGINAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Photocopy, photographer unknown, c. 1940-41 SOUTH ELEVATION WITH ORIGINAL PORCH REMOVED - White Deer Lake Camp, Chimney Cabin, Cyrus H. McCormick Experimental Forest, Champion, Marquette County, MI

  18. 15. Photocopy, photographer unknown, c. 1933 INTERIOR OF LIVING ROOM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Photocopy, photographer unknown, c. 1933 INTERIOR OF LIVING ROOM LOOKING EAST-NORTHEAST - White Deer Lake Camp, Living Room Cabin, Cyrus H. McCormick Experimental Forest, Champion, Marquette County, MI

  19. 10. Photocopy of map (from Benicia Historical Society) Delineator unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Photocopy of map (from Benicia Historical Society) Delineator unknown May 1, 1894, revised to Mar. 27, 1918 'MAP OF BENICIA ARSENAL RESERVATION' - Benicia Arsenal, Benicia Industrial Park, Benicia, Solano County, CA

  20. 51. Photographer unknown 1930 HUMBOLDT COUNTY, SECTION A, HIGHWAY 1. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. Photographer unknown 1930 HUMBOLDT COUNTY, SECTION A, HIGHWAY 1. 1-HUM-1-A #101, MEASURING BETWEEN TREES, 1930. Stamped office copy. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA