E/N effects on K0 values revealed by high precision measurements under low field conditions

NASA Astrophysics Data System (ADS)

Hauck, Brian C.; Siems, William F.; Harden, Charles S.; McHugh, Vincent M.; Hill, Herbert H.

2016-07-01

Ion mobility spectrometry (IMS) is used to detect chemical warfare agents, explosives, and narcotics. While IMS has a low rate of false positives, their occurrence causes the loss of time and money as the alarm is verified. Because numerous variables affect the reduced mobility (K0) of an ion, wide detection windows are required in order to ensure a low false negative response rate. Wide detection windows, however, reduce response selectivity, and interferents with similar K0 values may be mistaken for targeted compounds and trigger a false positive alarm. Detection windows could be narrowed if reference K0 values were accurately known for specific instrumental conditions. Unfortunately, there is a lack of confidence in the literature values due to discrepancies in the reported K0 values and their lack of reported error. This creates the need for the accurate control and measurement of each variable affecting ion mobility, as well as for a central accurate IMS database for reference and calibration. A new ion mobility spectrometer has been built that reduces the error of measurements affecting K0 by an order of magnitude less than ±0.2%. Precise measurements of ±0.002 cm2 V-1 s-1 or better have been produced and, as a result, an unexpected relationship between K0 and the electric field to number density ratio (E/N) has been discovered in which the K0 values of ions decreased as a function of E/N along a second degree polynomial trend line towards an apparent asymptote at approximately 4 Td.

A Novel Position Compensation Scheme for Cable-Pulley Mechanisms Used in Laparoscopic Surgical Robots

PubMed Central

Liang, Yunlei; Du, Zhijiang; Sun, Lining

2017-01-01

The tendon driven mechanism using a cable and pulley to transmit power is adopted by many surgical robots. However, backlash hysteresis objectively exists in cable-pulley mechanisms, and this nonlinear problem is a great challenge in precise position control during the surgical procedure. Previous studies mainly focused on the transmission characteristics of the cable-driven system and constructed transmission models under particular assumptions to solve nonlinear problems. However, these approaches are limited because the modeling process is complex and the transmission models lack general applicability. This paper presents a novel position compensation control scheme to reduce the impact of backlash hysteresis on the positioning accuracy of surgical robots’ end-effectors. In this paper, a position compensation scheme using a support vector machine based on feedforward control is presented to reduce the position tracking error. To validate the proposed approach, experimental validations are conducted on our cable-pulley system and comparative experiments are carried out. The results show remarkable improvements in the performance of reducing the positioning error for the use of the proposed scheme. PMID:28974011

Height bias and scale effect induced by antenna gravitational deformations in geodetic VLBI data analysis

NASA Astrophysics Data System (ADS)

Sarti, Pierguido; Abbondanza, Claudio; Petrov, Leonid; Negusini, Monia

2011-01-01

The impact of signal path variations (SPVs) caused by antenna gravitational deformations on geodetic very long baseline interferometry (VLBI) results is evaluated for the first time. Elevation-dependent models of SPV for Medicina and Noto (Italy) telescopes were derived from a combination of terrestrial surveying methods to account for gravitational deformations. After applying these models in geodetic VLBI data analysis, estimates of the antenna reference point positions are shifted upward by 8.9 and 6.7 mm, respectively. The impact on other parameters is negligible. To simulate the impact of antenna gravitational deformations on the entire VLBI network, lacking measurements for other telescopes, we rescaled the SPV models of Medicina and Noto for other antennas according to their size. The effects of the simulations are changes in VLBI heights in the range [-3, 73] mm and a net scale increase of 0.3-0.8 ppb. The height bias is larger than random errors of VLBI position estimates, implying the possibility of significant scale distortions related to antenna gravitational deformations. This demonstrates the need to precisely measure gravitational deformations of other VLBI telescopes, to derive their precise SPV models and to apply them in routine geodetic data analysis.

Agreement, the F-Measure, and Reliability in Information Retrieval

PubMed Central

Hripcsak, George; Rothschild, Adam S.

2005-01-01

Information retrieval studies that involve searching the Internet or marking phrases usually lack a well-defined number of negative cases. This prevents the use of traditional interrater reliability metrics like the κ statistic to assess the quality of expert-generated gold standards. Such studies often quantify system performance as precision, recall, and F-measure, or as agreement. It can be shown that the average F-measure among pairs of experts is numerically identical to the average positive specific agreement among experts and that κ approaches these measures as the number of negative cases grows large. Positive specific agreement—or the equivalent F-measure—may be an appropriate way to quantify interrater reliability and therefore to assess the reliability of a gold standard in these studies. PMID:15684123

Gene and Protein Expression following Exposure to Radiofrequency Fields from Mobile Phones

PubMed Central

Vanderstraeten, Jacques; Verschaeve, Luc

2008-01-01

Background Since 1999, several articles have been published on genome-wide and/or proteome-wide response after exposure to radiofrequency (RF) fields whose signal and intensities were similar to or typical of those of currently used mobile telephones. These studies were performed using powerful high-throughput screening techniques (HTSTs) of transcriptomics and/or proteomics, which allow for the simultaneous screening of the expression of thousands of genes or proteins. Objectives We reviewed these HTST-based studies and compared the results with currently accepted concepts about the effects of RF fields on gene expression. In this article we also discuss these last in light of the recent concept of microwave-assisted chemistry. Discussion To date, the results of HTST-based studies of transcriptomics and/or proteomics after exposure to RF fields relevant to human exposure are still inconclusive, as most of the positive reports are flawed by methodologic imperfections or shortcomings. In addition, when positive findings were reported, no precise response pattern could be identified in a reproducible way. In particular, results from HTST studies tend to exclude the role of a cell stressor for exposure to RF fields at nonthermal intensities. However, on the basis of lessons from microwave-assisted chemistry, we can assume that RF fields might affect heat-sensitive gene or protein expression to an extent larger than would be predicted from temperature change only. But in all likelihood, this would concern intensities higher than those relevant to usual human exposure. Conclusions The precise role of transcriptomics and proteomics in the screening of bioeffects from exposure to RF fields from mobile phones is still uncertain in view of the lack of positively identified phenotypic change and the lack of theoretical, as well as experimental, arguments for specific gene and/or protein response patterns after this kind of exposure. PMID:18795152

Accuracy and Measurement Error of the Medial Clear Space of the Ankle.

PubMed

Metitiri, Ogheneochuko; Ghorbanhoseini, Mohammad; Zurakowski, David; Hochman, Mary G; Nazarian, Ara; Kwon, John Y

2017-04-01

Measurement of the medial clear space (MCS) is commonly used to assess deltoid ligament competency and mortise stability when managing ankle fractures. Lacking knowledge of the true anatomic width measured, previous studies have been unable to measure accuracy of measurement. The purpose of this study was to determine MCS measurement error and accuracy and any influencing factors. Using 3 normal transtibial ankle cadaver specimens, deltoid and syndesmotic ligaments were transected and the mortise widened and affixed at a width of 6 mm (specimen 1) and 4 mm (specimen 2). The mortise was left intact in specimen 3. Radiographs were obtained of each cadaver at varying degrees of rotation. Radiographs were randomized, and providers measured the MCS using a standardized technique. Lack of accuracy as well as lack of precision in measurement of the medial clear space compared to a known anatomic value was present for all 3 specimens tested. There were no significant differences in mean delta with regard to level of training for specimens 1 and 2; however, with specimen 3, staff physicians showed increased measurement accuracy compared with trainees. Accuracy and precision of MCS measurements are poor. Provider experience did not appear to influence accuracy and precision of measurements for the displaced mortise. This high degree of measurement error and lack of precision should be considered when deciding treatment options based on MCS measurements.

Long-term impact of a precision agriculture system on grain crop production

USDA-ARS?s Scientific Manuscript database

Research is lacking on the long-term impacts of field-scale precision agriculture practices on grain production. Following more than a decade (1993-2003) of yield and soil mapping and water quality assessment, a multi-faceted, ‘precision agriculture system’ (PAS) was implemented from 2004 to 2014 on...

High precision applications of the global positioning system

NASA Technical Reports Server (NTRS)

Lichten, Stephen M.

1991-01-01

The Global Positioning System (GPS) is a constellation of U.S. defense navigation satellites which can be used for military and civilian positioning applications. A wide variety of GPS scientific applications were identified and precise positioning capabilities with GPS were already demonstrated with data available from the present partial satellite constellation. Expected applications include: measurements of Earth crustal motion, particularly in seismically active regions; measurements of the Earth's rotation rate and pole orientation; high-precision Earth orbiter tracking; surveying; measurements of media propagation delays for calibration of deep space radiometric data in support of NASA planetary missions; determination of precise ground station coordinates; and precise time transfer worldwide.

Positioning performance of a maglev fine positioning system

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

Wronosky, J.B.; Smith, T.G.; Jordan, J.D.

1996-12-01

A wafer positioning system was recently developed by Sandia National Laboratories for an Extreme Ultraviolet Lithography (EUVL) research tool. The system, which utilizes a magnetically levitated fine stage to provide ultra-precise positioning in all six degrees of freedom, incorporates technological improvements resulting from four years of prototype development experience. System enhancements, implemented on a second generation design for an ARPA National Center for Advanced Information Component Manufacturing (NCAICM) project, introduced active structural control for the levitated structure of the system. Magnetic levitation (maglev) is emerging as an important technology for wafer positioning systems in advanced lithography applications. The advantages ofmore » maglev stem from the absence of physical contact. The resulting lack of friction enables accurate, fast positioning. Maglev systems are mechanically simple, accomplishing full six degree-of-freedom suspension and control with a minimum of moving parts. Power-efficient designs, which reduce the possibility of thermal distortion of the platen, are achievable. Manufacturing throughput will be improved in future systems with the addition of active structural control of the positioning stages. This paper describes the design, implementation, and functional capability of the maglev fine positioning system. Specifics regarding performance design goals and test results are presented.« less

Towards a compact and precise sample holder for macromolecular crystallography.

PubMed

Papp, Gergely; Rossi, Christopher; Janocha, Robert; Sorez, Clement; Lopez-Marrero, Marcos; Astruc, Anthony; McCarthy, Andrew; Belrhali, Hassan; Bowler, Matthew W; Cipriani, Florent

2017-10-01

Most of the sample holders currently used in macromolecular crystallography offer limited storage density and poor initial crystal-positioning precision upon mounting on a goniometer. This has now become a limiting factor at high-throughput beamlines, where data collection can be performed in a matter of seconds. Furthermore, this lack of precision limits the potential benefits emerging from automated harvesting systems that could provide crystal-position information which would further enhance alignment at beamlines. This situation provided the motivation for the development of a compact and precise sample holder with corresponding pucks, handling tools and robotic transfer protocols. The development process included four main phases: design, prototype manufacture, testing with a robotic sample changer and validation under real conditions on a beamline. Two sample-holder designs are proposed: NewPin and miniSPINE. They share the same robot gripper and allow the storage of 36 sample holders in uni-puck footprint-style pucks, which represents 252 samples in a dry-shipping dewar commonly used in the field. The pucks are identified with human- and machine-readable codes, as well as with radio-frequency identification (RFID) tags. NewPin offers a crystal-repositioning precision of up to 10 µm but requires a specific goniometer socket. The storage density could reach 64 samples using a special puck designed for fully robotic handling. miniSPINE is less precise but uses a goniometer mount compatible with the current SPINE standard. miniSPINE is proposed for the first implementation of the new standard, since it is easier to integrate at beamlines. An upgraded version of the SPINE sample holder with a corresponding puck named SPINEplus is also proposed in order to offer a homogenous and interoperable system. The project involved several European synchrotrons and industrial companies in the fields of consumables and sample-changer robotics. Manual handling of miniSPINE was tested at different institutes using evaluation kits, and pilot beamlines are being equipped with compatible robotics for large-scale evaluation. A companion paper describes a new sample changer FlexED8 (Papp et al., 2017, Acta Cryst., D73, 841-851).

Operator Variability in Scan Positioning is a Major Component of HR-pQCT Precision Error and is Reduced by Standardized Training

PubMed Central

Bonaretti, Serena; Vilayphiou, Nicolas; Chan, Caroline Mai; Yu, Andrew; Nishiyama, Kyle; Liu, Danmei; Boutroy, Stephanie; Ghasem-Zadeh, Ali; Boyd, Steven K.; Chapurlat, Roland; McKay, Heather; Shane, Elizabeth; Bouxsein, Mary L.; Black, Dennis M.; Majumdar, Sharmila; Orwoll, Eric S.; Lang, Thomas F.; Khosla, Sundeep; Burghardt, Andrew J.

2017-01-01

Introduction HR-pQCT is increasingly used to assess bone quality, fracture risk and anti-fracture interventions. The contribution of the operator has not been adequately accounted in measurement precision. Operators acquire a 2D projection (“scout view image”) and define the region to be scanned by positioning a “reference line” on a standard anatomical landmark. In this study, we (i) evaluated the contribution of positioning variability to in vivo measurement precision, (ii) measured intra- and inter-operator positioning variability, and (iii) tested if custom training software led to superior reproducibility in new operators compared to experienced operators. Methods To evaluate the operator in vivo measurement precision we compared precision errors calculated in 64 co-registered and non-co-registered scan-rescan images. To quantify operator variability, we developed software that simulates the positioning process of the scanner’s software. Eight experienced operators positioned reference lines on scout view images designed to test intra- and inter-operator reproducibility. Finally, we developed modules for training and evaluation of reference line positioning. We enrolled 6 new operators to participate in a common training, followed by the same reproducibility experiments performed by the experienced group. Results In vivo precision errors were up to three-fold greater (Tt.BMD and Ct.Th) when variability in scan positioning was included. Inter-operator precision errors were significantly greater than short-term intra-operator precision (p<0.001). New trained operators achieved comparable intra-operator reproducibility to experienced operators, and lower inter-operator reproducibility (p<0.001). Precision errors were significantly greater for the radius than for the tibia. Conclusion Operator reference line positioning contributes significantly to in vivo measurement precision and is significantly greater for multi-operator datasets. Inter-operator variability can be significantly reduced using a systematic training platform, now available online (http://webapps.radiology.ucsf.edu/refline/). PMID:27475931

A Lane-Level LBS System for Vehicle Network with High-Precision BDS/GPS Positioning

PubMed Central

Guo, Chi; Guo, Wenfei; Cao, Guangyi; Dong, Hongbo

2015-01-01

In recent years, research on vehicle network location service has begun to focus on its intelligence and precision. The accuracy of space-time information has become a core factor for vehicle network systems in a mobile environment. However, difficulties persist in vehicle satellite positioning since deficiencies in the provision of high-quality space-time references greatly limit the development and application of vehicle networks. In this paper, we propose a high-precision-based vehicle network location service to solve this problem. The major components of this study include the following: (1) application of wide-area precise positioning technology to the vehicle network system. An adaptive correction message broadcast protocol is designed to satisfy the requirements for large-scale target precise positioning in the mobile Internet environment; (2) development of a concurrence service system with a flexible virtual expansion architecture to guarantee reliable data interaction between vehicles and the background; (3) verification of the positioning precision and service quality in the urban environment. Based on this high-precision positioning service platform, a lane-level location service is designed to solve a typical traffic safety problem. PMID:25755665

Modeling and Positioning of a PZT Precision Drive System.

PubMed

Liu, Che; Guo, Yanling

2017-11-08

The fact that piezoelectric ceramic transducer (PZT) precision drive systems in 3D printing are faced with nonlinear problems with respect to positioning, such as hysteresis and creep, has had an extremely negative impact on the precision of laser focusing systems. To eliminate the impact of PZT nonlinearity during precision drive movement, mathematical modeling and theoretical analyses of each module comprising the system were carried out in this study, a micro-displacement measurement circuit based on Position Sensitive Detector (PSD) is constructed, followed by the establishment of system closed-loop control and creep control models. An XL-80 laser interferometer (Renishaw, Wotton-under-Edge, UK) was used to measure the performance of the precision drive system, showing that system modeling and control algorithms were correct, with the requirements for precision positioning of the drive system satisfied.

Modeling and Positioning of a PZT Precision Drive System

PubMed Central

Liu, Che; Guo, Yanling

2017-01-01

The fact that piezoelectric ceramic transducer (PZT) precision drive systems in 3D printing are faced with nonlinear problems with respect to positioning, such as hysteresis and creep, has had an extremely negative impact on the precision of laser focusing systems. To eliminate the impact of PZT nonlinearity during precision drive movement, mathematical modeling and theoretical analyses of each module comprising the system were carried out in this study, a micro-displacement measurement circuit based on Position Sensitive Detector (PSD) is constructed, followed by the establishment of system closed-loop control and creep control models. An XL-80 laser interferometer (Renishaw, Wotton-under-Edge, UK) was used to measure the performance of the precision drive system, showing that system modeling and control algorithms were correct, with the requirements for precision positioning of the drive system satisfied. PMID:29117140

Information encoded in non-native states drives substrate-chaperone pairing.

PubMed

Mapa, Koyeli; Tiwari, Satyam; Kumar, Vignesh; Jayaraj, Gopal Gunanathan; Maiti, Souvik

2012-09-05

Many proteins refold in vitro through kinetic folding intermediates that are believed to be by-products of native-state centric evolution. These intermediates are postulated to play only minor roles, if any, in vivo because they lack any information related to translation-associated vectorial folding. We demonstrate that refolding intermediate of a test protein, generated in vitro, is able to find its cognate chaperone, from the whole complement of Escherichia coli soluble chaperones. Cognate chaperone-binding uniquely alters the conformation of non-native substrate. Importantly, precise chaperone targeting of substrates are maintained as long as physiological molar ratios of chaperones remain unaltered. Using a library of different chaperone substrates, we demonstrate that kinetically trapped refolding intermediates contain sufficient structural features for precise targeting to cognate chaperones. We posit that evolution favors sequences that, in addition to coding for a functional native state, encode folding intermediates with higher affinity for cognate chaperones than noncognate ones. Copyright © 2012 Elsevier Ltd. All rights reserved.

Improvement of absolute positioning of precision stage based on cooperation the zero position pulse signal and incremental displacement signal

NASA Astrophysics Data System (ADS)

Wang, H. H.; Shi, Y. P.; Li, X. H.; Ni, K.; Zhou, Q.; Wang, X. H.

2018-03-01

In this paper, a scheme to measure the position of precision stages, with a high precision, is presented. The encoder is composed of a scale grating and a compact two-probe reading head, to read the zero position pulse signal and continuous incremental displacement signal. The scale grating contains different codes, multiple reference codes with different spacing superimposed onto the incremental grooves with an equal spacing structure. The codes of reference mask in the reading head is the same with the reference codes on the scale grating, and generate pulse signal to locate the reference position primarily when the reading head moves along the scale grating. After locating the reference position in a section by means of the pulse signal, the reference position can be located precisely with the amplitude of the incremental displacement signal. A kind of reference codes and scale grating were designed, and experimental results show that the primary precision of the design achieved is 1 μ m. The period of the incremental signal is 1μ m, and 1000/N nm precision can be achieved by subdivide the incremental signal in N times.

Multi-GNSS real-time precise orbit/clock/UPD products and precise positioning service at GFZ

NASA Astrophysics Data System (ADS)

Li, Xingxing; Ge, Maorong; Liu, Yang; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

2016-04-01

The rapid development of multi-constellation GNSSs (Global Navigation Satellite Systems, e.g., BeiDou, Galileo, GLONASS, GPS) and the IGS (International GNSS Service) Multi-GNSS Experiment (MGEX) bring great opportunities and challenges for real-time precise positioning service. In this contribution, we present a GPS+GLONASS+BeiDou+Galileo four-system model to fully exploit the observations of all these four navigation satellite systems for real-time precise orbit determination, clock estimation and positioning. A rigorous multi-GNSS analysis is performed to achieve the best possible consistency by processing the observations from different GNSS together in one common parameter estimation procedure. Meanwhile, an efficient multi-GNSS real-time precise positioning service system is designed and demonstrated by using the Multi-GNSS Experiment (MGEX) and International GNSS Service (IGS) data streams including stations all over the world. The addition of the BeiDou, Galileo and GLONASS systems to the standard GPS-only processing, reduces the convergence time almost by 70%, while the positioning accuracy is improved by about 25%. Some outliers in the GPS-only solutions vanish when multi-GNSS observations are processed simultaneous. The availability and reliability of GPS precise positioning decrease dramatically as the elevation cutoff increases. However, the accuracy of multi-GNSS precise point positioning (PPP) is hardly decreased and few centimeters are still achievable in the horizontal components even with 40° elevation cutoff.

a Micro-Uav with the Capability of Direct Georeferencing

NASA Astrophysics Data System (ADS)

Rehak, M.; Mabillard, R.; Skaloud, J.

2013-08-01

This paper presents the development of a low cost UAV (Unmanned Aerial Vehicle) with the capability of direct georeferencing. The advantage of such system lies in its high maneuverability, operation flexibility as well as capability to acquire image data without the need of establishing ground control points (GCPs). Moreover, the precise georeferencing offers an improvement in the final mapping accuracy when employing integrated sensor orientation. Such mode of operation limits the number and distribution of GCPs, which in turns save time in their signalization and surveying. Although the UAV systems feature high flexibility and capability of flying into areas that are inhospitable or inaccessible to humans, the lack of precision in positioning and attitude estimation on-board decrease the gained value of the captured imagery and limits their mode of operation to specific configurations and need of groundreference. Within a scope of this study we show the potential of present technologies in the field of position and orientation determination on a small UAV. The hardware implementation and especially the non-trivial synchronization of all components is clarified. Thanks to the implementation of a multi-frequency, low power GNSS receiver and its coupling with redundant MEMSIMU, we can attain the characteristic of a much larger systems flown on large carries while keeping the sensor size and weight suitable for MAV operations.

Lane-Level Vehicle Positioning : Integrating Diverse Systems for Precision and Reliability

DOT National Transportation Integrated Search

2013-05-13

Integrated global positioning system/inertial navigation system (GPS/INS) technology, the backbone of vehicle positioning systems, cannot provide the precision and reliability needed for vehicle-based, lane-level positioning in all driving environmen...

Perceived barriers to physical activity among Polish adolescents.

PubMed

Jodkowska, Maria; Mazur, Joanna; Oblacińska, Anna

2015-01-01

To identify barriers to physical activity (PA) for adolescents according to the gender and age and examine the association between these barriers and youths' physical activity. 3346 students aged 10-16 years (1759 girls) took part in the cross-sectional, nationally representative study. For this paper the dataset was created from adolescents who reported perceived barriers to PA, N = 2300, (1259 girls), range 13-16 years. Barriers and physical activity (MVPA) were analysed for all participants, as well as by gender, age group and place of residence. Multiple regression analysis was used to examine the relationships between perceived barriers and physical inactivity for all and than separately for boys and girls. Lack of energy, lack of time and lack of support were three of the five barriers reported by more than 40% of adolescents, statistically more likely by girls than boys and older youth than younger. For boys - lack of time (OR = 2.56; CI = 1.66-3.96), lack of skills (OR = 2.35; CI = 1.94-3.95), lack of willpower (OR = 1.71, CI = 1.05-2.80) and lack of support (OR = 1.64, CI = 1.11-2.41) were the predictors contributing to low level of PA. For girls lack of skills (OR = 3.16, CI = 1.62-6.18), lack of energy (OR = 1.84, CI = 1.14-2.96), lack of support (OR = 1.64, CI = 1.07-2.54) and lack of time (OR = 1.61,CI = 1.00-2.60) were positively and statistically significant associated with physical inactivity. 1. Perceived barriers to physical activity among adolescents have strong negative impact on recommended PA level. For girls lack of skills is the strongest predictor of low PA, for boys - lack of time. 2. Identification more precisely barriers to physical activity among adolescents will enable to developed more effective interventions in high-risk populations.

Record-Breaking Radio Astronomy Project to Measure Sky with Extreme Precision

NASA Astrophysics Data System (ADS)

2009-11-01

Astronomers will tie together the largest collection of the world's radio telescopes ever assembled to work as a single observing tool in a project aimed at improving the precision of the reference frame scientists use to measure positions in the sky. The National Science Foundation's Very Long Baseline Array (VLBA) will be a key part of the project, which is coordinated by the International VLBI Service for Geodesy and Astrometry. For 24 hours, starting Wednesday, November 18, and ending Thursday, November 19, 35 radio telescopes located on seven continents will observe 243 distant quasars. The quasars, galaxies with supermassive black holes at their cores, are profuse emitters of radio waves, and also are so distant that, despite their actual motions in space, they appear stationary as seen from Earth. This lack of apparent motion makes them ideal celestial landmarks for anchoring a grid system, similar to earthly latitude and longitude, used to mark the positions of celestial objects. Data from all the radio telescopes will be combined to make them work together as a system capable of measuring celestial positions with extremely high precision. The technique used, called very long baseline interferometry (VLBI), has been used for decades for both astronomical and geodetic research. However, no previous position-measuring observation has used as many radio telescopes or observed as many objects in a single session. The previous record was a 23-telescope observation. At a meeting in Brazil last August, the International Astronomical Union adopted a new reference frame for celestial positions that will be used starting on January 1. This new reference frame uses a set of 295 quasars to define positions, much like surveyor's benchmarks in a surburban subdivision. Because even with 35 radio telescopes around the world, there are some gaps in sky coverage, the upcoming observation will observe 243 of the 295. By observing so many quasars in a single observing session, problems of linking positions from one observing session to another can be avoided, the astronomers say. The result will be a much stronger, more precise, reference grid. Telescopes in Asia, Australia, Europe, North America, South America, Antarctica, and in the Pacific will participate. Improving the celestial positional grid will allow astronomers better to pinpoint the locations and measure the motions of objects in the sky. As astronomers increasingly study objects using multiple telescopes observing at different wavelengths, such as visible light, radio, infrared, etc., the improved positional grid will allow more accurate overlaying of the different images. The improved celestial reference frame also strengthens a terrestrial reference frame used for radio-telescope measurements that contribute to geophysical research. The precise geodetic measurements help geophysicists understand phenomena such as plate tectonics, earth tides, and processes that affect our planet's orientation in space. The VLBA is a continent-wide radio telescope system with 10, 240-ton dish antennas ranging from Hawaii to the Virgin Islands. Operated from the National Radio Astronomy Observatory's Pete V. Domenici Science Operations Center in Socorro, New Mexico, the VLBA offers the greatest resolving power, or ability to see fine detail, of any telescope in astronomy. The multi-telescope observation will be accompanied by public-outreach activities in celebration of the International Year of Astronomy. A public web page devoted to the observation will be hosted at Bordeaux Observatory, and some of the participating telescopes will have webcams available.

Centroiding Experiment for Determining the Positions of Stars with High Precision

NASA Astrophysics Data System (ADS)

Yano, T.; Araki, H.; Hanada, H.; Tazawa, S.; Gouda, N.; Kobayashi, Y.; Yamada, Y.; Niwa, Y.

2010-12-01

We have experimented with the determination of the positions of star images on a detector with high precision such as 10 microarcseconds, required by a space astrometry satellite, JASMINE. In order to accomplish such a precision, we take the following two procedures. (1) We determine the positions of star images on the detector with the precision of about 0.01 pixel for one measurement, using an algorithm for estimating them from photon weighted means of the star images. (2) We determine the positions of star images with the precision of about 0.0001-0.00001 pixel, which corresponds to that of 10 microarcseconds, using a large amount of data over 10000 measurements, that is, the error of the positions decreases according to the amount of data. Here, we note that the procedure 2 is not accomplished when the systematic error in our data is not excluded adequately even if we use a large amount of data. We first show the method to determine the positions of star images on the detector using photon weighted means of star images. This algorithm, used in this experiment, is very useful because it is easy to calculate the photon weighted mean from the data. This is very important in treating a large amount of data. Furthermore, we need not assume the shape of the point spread function in deriving the centroid of star images. Second, we show the results in the laboratory experiment for precision of determining the positions of star images. We obtain that the precision of estimation of positions of star images on the detector is under a variance of 0.01 pixel for one measurement (procedure 1). We also obtain that the precision of the positions of star images becomes a variance of about 0.0001 pixel using about 10000 measurements (procedure 2).

Determination of Precise Satellite Orbital Position Using Multi-Band GNSS Signals

DTIC Science & Technology

2017-10-16

AFRL-AFOSR-JP-TR-2018-0002 Determination of Precise Satellite Orbital Position Using Multi -Band GNSS Signals Erry Gunawan NANYANG TECHNOLOGICAL...Position Using Multi -Band GNSS Signals 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-15-1-4041 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Erry...Grant FA2386-15-1-4041 “Determination of Precise orbital position using multi -band GNSS signals” October 13, 2017 Name of Principal Investigators

Fabrication of fixed implant prostheses using function bite impression technique (FBI technique).

PubMed

Suzuki, Yasunori; Shimpo, Hidemasa; Ohkubo, Chikahiro; Kurtz, Kenneth S

2012-10-01

The patient was partially edentulous, lacking both the first mandibular molars. The FBI and the conventional impression technique were used for the fabrication of implant-fixed prosthesis replacing the right and left molars, respectively. In the FBI technique, the definitive impression was made under occlusal force and functionally generated path (FGP) recording at the same time. The right and left occlusal contact areas were compared after completing the implant-fixed prosthesis rehabilitation. It has been suggested that accuracy of the impression and maxillomandibular registration is necessary to ensure a satisfactory long-term clinical outcome. The transfer of the exact position of the implants to the working cast is even more important because implants lack the mobility of natural teeth. There are displacement differences between implants and natural teeth under occlusal force. The FBI technique may compensate for this difference in accuracy. Using the FBI technique, a precise prosthesis could be produced by completing simultaneously the maxillomandibular registration, impression and FGP. Copyright © 2012 Japan Prosthodontic Society. All rights reserved.

High precision locating control system based on VCM for Talbot lithography

NASA Astrophysics Data System (ADS)

Yao, Jingwei; Zhao, Lixin; Deng, Qian; Hu, Song

2016-10-01

Aiming at the high precision and efficiency requirements of Z-direction locating in Talbot lithography, a control system based on Voice Coil Motor (VCM) was designed. In this paper, we built a math model of VCM and its moving characteristic was analyzed. A double-closed loop control strategy including position loop and current loop were accomplished. The current loop was implemented by driver, in order to achieve the rapid follow of the system current. The position loop was completed by the digital signal processor (DSP) and the position feedback was achieved by high precision linear scales. Feed forward control and position feedback Proportion Integration Differentiation (PID) control were applied in order to compensate for dynamic lag and improve the response speed of the system. And the high precision and efficiency of the system were verified by simulation and experiments. The results demonstrated that the performance of Z-direction gantry was obviously improved, having high precision, quick responses, strong real-time and easily to expend for higher precision.

Study on high-precision measurement of long radius of curvature

NASA Astrophysics Data System (ADS)

Wu, Dongcheng; Peng, Shijun; Gao, Songtao

2016-09-01

It is hard to get high-precision measurement of the radius of curvature (ROC), because of many factors that affect the measurement accuracy. For the measurement of long radius of curvature, some factors take more important position than others'. So, at first this paper makes some research about which factor is related to the long measurement distance, and also analyse the uncertain of the measurement accuracy. At second this article also study the influence about the support status and the adjust error about the cat's eye and confocal position. At last, a 1055micrometer radius of curvature convex is measured in high-precision laboratory. Experimental results show that the proper steady support (three-point support) can guarantee the high-precision measurement of radius of curvature. Through calibrating the gain of cat's eye and confocal position, is useful to ensure the precise position in order to increase the measurement accuracy. After finish all the above process, the high-precision long ROC measurement is realized.

Variation of Static-PPP Positioning Accuracy Using GPS-Single Frequency Observations (Aswan, Egypt)

NASA Astrophysics Data System (ADS)

Farah, Ashraf

2017-06-01

Precise Point Positioning (PPP) is a technique used for position computation with a high accuracy using only one GNSS receiver. It depends on highly accurate satellite position and clock data rather than broadcast ephemeries. PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of collected observations. PPP-(dual frequency receivers) offers comparable accuracy to differential GPS. PPP-single frequency receivers has many applications such as infrastructure, hydrography and precision agriculture. PPP using low cost GPS single-frequency receivers is an area of great interest for millions of users in developing countries such as Egypt. This research presents a study for the variability of single frequency static GPS-PPP precision based on different observation durations.

Analysis of the Image Quality of no Ground Controlled Positioning Precision about Surveying and Mapping Satellite

NASA Astrophysics Data System (ADS)

Wang, Y.; Hu, X.; Yang, X.; Xie, G.

2018-04-01

The image quality of the surveying camera will affect the stereoscopic positioning accuracy of the remote sensing satellite. The key factors closely related to the image quality are Modulation Transfer Function(MTF),Signal to Noise Ratio(SNR) and Quantization Bits(QB). In "Mapping Satellite-1" image as the background, research the effect of positioning precision about the image quality in no ground controlled conditions, and evaluate the quantitative relationship with the positioning precision. At last verify the validity of the experimental results by simulating three factors of the degraded data on orbit, and counting the number of matching points, the mismatch rate, and the matching residuals of the degraded data. The reason for the variety of the positioning precision was analyzed.

Intravesical dosimetry applied to laser positioning in photodynamic therapy

NASA Astrophysics Data System (ADS)

Beslon, Guillaume; Ambroise, Philippe; Heit, Bernard; Bremont, Jacques; Guillemin, Francois H.

1996-12-01

Superficial bladder tumor is a challenging indication for photodynamic therapy. Due to lack of specificity of the sensitizers, the light has to be precisely monitored over the bladder surface, illuminated by an isotropic source, to restrict the cytotoxic effect to the tumor without affecting the normal epithelium. In order to assist the surgeon while processing the therapy, an urothelium illumination model is proposed. It is computed through a spline interpolation, on the basis of 12 intravesical sensors. This paper presents the overall system architecture and details the modelization and visualization processes. With this model, the surgeon is able to master the source displacement inside the bladder and to homogenize the tissue exposure.

The Confluence of Stereotactic Ablative Radiotherapy and Tumor Immunology

PubMed Central

Finkelstein, Steven Eric; Timmerman, Robert; McBride, William H.; Schaue, Dörthe; Hoffe, Sarah E.; Mantz, Constantine A.; Wilson, George D.

2011-01-01

Stereotactic radiation approaches are gaining more popularity for the treatment of intracranial as well as extracranial tumors in organs such as the liver and lung. Technology, rather than biology, is driving the rapid adoption of stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy (SABR), in the clinic due to advances in precise positioning and targeting. Dramatic improvements in tumor control have been demonstrated; however, our knowledge of normal tissue biology response mechanisms to large fraction sizes is lacking. Herein, we will discuss how SABR can induce cellular expression of MHC I, adhesion molecules, costimulatory molecules, heat shock proteins, inflammatory mediators, immunomodulatory cytokines, and death receptors to enhance antitumor immune responses. PMID:22162711

Research regarding the influence of driving-wires length change on positioning precision of a robotic arm

NASA Astrophysics Data System (ADS)

Ciofu, C.; Stan, G.

2016-08-01

The paper emphasise positioning precision of an elephant's trunk robotic arm which has joints driven by wires with variable length while operating The considered 5 degrees of freedom robotic arm has a particular structure of joint that makes possible inner actuation with wire-driven mechanism. We analyse solely the length change of wires as a consequence due inner winding and unwinding on joints for certain values of rotational angles. Variations in wires length entail joint angular displacements. We analyse positioning precision by taking into consideration equations from inverse kinematics of the elephant's trunk robotic arm. The angular displacements of joints are considered into computational method after partial derivation of positioning equations. We obtain variations of wires length at about tenths of micrometers. These variations employ angular displacements which are about minutes of sexagesimal degree and, thus, define positioning precision of elephant's trunk robotic arms. The analytical method is used for determining aftermath design structure of an elephant's trunk robotic arm with inner actuation through wires on positioning precision. Thus, designers could take suitable decisions on accuracy specifications limits of the robotic arm.

Precision Relative Positioning for Automated Aerial Refueling from a Stereo Imaging System

DTIC Science & Technology

2015-03-01

PRECISION RELATIVE POSITIONING FOR AUTOMATED AERIAL REFUELING FROM A STEREO IMAGING SYSTEM THESIS Kyle P. Werner, 2Lt, USAF AFIT-ENG-MS-15-M-048...REFUELING FROM A STEREO IMAGING SYSTEM THESIS Presented to the Faculty Department of Electrical and Computer Engineering Graduate School of...RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENG-MS-15-M-048 PRECISION RELATIVE POSITIONING FOR AUTOMATED AERIAL REFUELING FROM A STEREO IMAGING SYSTEM THESIS

Development of Precision Pointing Controllers with and Without Vibration Suppression for the NPS Precision Pointing Hexapod

DTIC Science & Technology

2002-12-01

applications, vibration sources are numerous such as: ! Launch Loading ! Man-induced accelerations like on the Shuttle or space station ! Solar ...However, the lack of significant tracking errors during times when other actuators were stationary, and the fact that the local maximum tracking...

Performance Evaluation of Real-Time Precise Point Positioning Method

NASA Astrophysics Data System (ADS)

Alcay, Salih; Turgut, Muzeyyen

2017-12-01

Post-Processed Precise Point Positioning (PPP) is a well-known zero-difference positioning method which provides accurate and precise results. After the experimental tests, IGS Real Time Service (RTS) officially provided real time orbit and clock products for the GNSS community that allows real-time (RT) PPP applications. Different software packages can be used for RT-PPP. In this study, in order to evaluate the performance of RT-PPP, 3 IGS stations are used. Results, obtained by using BKG Ntrip Client (BNC) Software v2.12, are examined in terms of both accuracy and precision.

Analysis of de-noising methods to improve the precision of the ILSF BPM electronic readout system

NASA Astrophysics Data System (ADS)

Shafiee, M.; Feghhi, S. A. H.; Rahighi, J.

2016-12-01

In order to have optimum operation and precise control system at particle accelerators, it is required to measure the beam position with the precision of sub-μm. We developed a BPM electronic readout system at Iranian Light Source Facility and it has been experimentally tested at ALBA accelerator facility. The results show the precision of 0.54 μm in beam position measurements. To improve the precision of this beam position monitoring system to sub-μm level, we have studied different de-noising methods such as principal component analysis, wavelet transforms, filtering by FIR, and direct averaging method. An evaluation of the noise reduction was given to testify the ability of these methods. The results show that the noise reduction based on Daubechies wavelet transform is better than other algorithms, and the method is suitable for signal noise reduction in beam position monitoring system.

Precision mechanical structure of an ultra-high-resolution spectrometer for inelastic X-ray scattering instrument

DOEpatents

Shu, Deming; Shvydko, Yuri; Stoupin, Stanislav A.; Khachatryan, Ruben; Goetze, Kurt A.; Roberts, Timothy

2015-04-14

A method and an ultrahigh-resolution spectrometer including a precision mechanical structure for positioning inelastic X-ray scattering optics are provided. The spectrometer includes an X-ray monochromator and an X-ray analyzer, each including X-ray optics of a collimating (C) crystal, a pair of dispersing (D) element crystals, anomalous transmission filter (F) and a wavelength (W) selector crystal. A respective precision mechanical structure is provided with the X-ray monochromator and the X-ray analyzer. The precision mechanical structure includes a base plate, such as an aluminum base plate; positioning stages for D-crystal alignment; positioning stages with an incline sensor for C/F/W-crystal alignment, and the positioning stages including flexure-based high-stiffness structure.

Juvenile Osprey Navigation during Trans-Oceanic Migration

PubMed Central

Horton, Travis W.; Bierregaard, Richard O.; Zawar-Reza, Peyman; Holdaway, Richard N.; Sagar, Paul

2014-01-01

To compensate for drift, an animal migrating through air or sea must be able to navigate. Although some species of bird, fish, insect, mammal, and reptile are capable of drift compensation, our understanding of the spatial reference frame, and associated coordinate space, in which these navigational behaviors occur remains limited. Using high resolution satellite-monitored GPS track data, we show that juvenile ospreys (Pandion haliaetus) are capable of non-stop constant course movements over open ocean spanning distances in excess of 1500 km despite the perturbing effects of winds and the lack of obvious landmarks. These results are best explained by extreme navigational precision in an exogenous spatio-temporal reference frame, such as positional orientation relative to Earth's magnetic field and pacing relative to an exogenous mechanism of keeping time. Given the age (<1 year-old) of these birds and knowledge of their hatching site locations, we were able to transform Enhanced Magnetic Model coordinate locations such that the origin of the magnetic coordinate space corresponded with each bird's nest. Our analyses show that trans-oceanic juvenile osprey movements are consistent with bicoordinate positional orientation in transformed magnetic coordinate or geographic space. Through integration of movement and meteorological data, we propose a new theoretical framework, chord and clock navigation, capable of explaining the precise spatial orientation and temporal pacing performed by juvenile ospreys during their long-distance migrations over open ocean. PMID:25493430

Indoor high precision three-dimensional positioning system based on visible light communication using modified genetic algorithm

NASA Astrophysics Data System (ADS)

Chen, Hao; Guan, Weipeng; Li, Simin; Wu, Yuxiang

2018-04-01

To improve the precision of indoor positioning and actualize three-dimensional positioning, a reversed indoor positioning system based on visible light communication (VLC) using genetic algorithm (GA) is proposed. In order to solve the problem of interference between signal sources, CDMA modulation is used. Each light-emitting diode (LED) in the system broadcasts a unique identity (ID) code using CDMA modulation. Receiver receives mixed signal from every LED reference point, by the orthogonality of spreading code in CDMA modulation, ID information and intensity attenuation information from every LED can be obtained. According to positioning principle of received signal strength (RSS), the coordinate of the receiver can be determined. Due to system noise and imperfection of device utilized in the system, distance between receiver and transmitters will deviate from the real value resulting in positioning error. By introducing error correction factors to global parallel search of genetic algorithm, coordinates of the receiver in three-dimensional space can be determined precisely. Both simulation results and experimental results show that in practical application scenarios, the proposed positioning system can realize high precision positioning service.

[Proton imaging applications for proton therapy: state of the art].

PubMed

Amblard, R; Floquet, V; Angellier, G; Hannoun-Lévi, J M; Hérault, J

2015-04-01

Proton therapy allows a highly precise tumour volume irradiation with a low dose delivered to the healthy tissues. The steep dose gradients observed and the high treatment conformity require a precise knowledge of the proton range in matter and the target volume position relative to the beam. Thus, proton imaging allows an improvement of the treatment accuracy, and thereby, in treatment quality. Initially suggested in 1963, radiographic imaging with proton is still not used in clinical routine. The principal difficulty is the lack of spatial resolution, induced by the multiple Coulomb scattering of protons with nuclei. Moreover, its realization for all clinical locations requires relatively high energies that are previously not considered for clinical routine. Abandoned for some time in favor of X-ray technologies, research into new imaging methods using protons is back in the news because of the increase of proton radiation therapy centers in the world. This article exhibits a non-exhaustive state of the art in proton imaging. Copyright © 2015 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Global investigations of the satellite-based Fugro OmniSTAR HP service

NASA Astrophysics Data System (ADS)

Pflugmacher, Andreas; Heister, Hansbert; Heunecke, Otto

2009-12-01

OmniSTAR is one of the world's leading suppliers of satellite-based augmentation services for onshore and offshore GNSS applications. OmniSTAR currently offers three services: VBS, HP and XP. OmniSTAR VBS is the code-based service, suitable for sub-metre positioning accuracy. The HP and XP services provide sub-decimetre accuracy, with the HP service based on a precise differential methodology and the XP service uses precise absolute positioning. The sub-decimetre HP and XP services both have distinctive convergence behaviour, and the positioning task is essentially a time-dependent process during which the accuracy of the estimated coordinates continuously improves over time. To validate the capabilities of the OmniSTAR services, and in particular the HP (High Performance) service, globally distributed measurement campaigns were performed. The results of these investigations confirm that the HP service satisfies its high accuracy specification, but only after a sufficient initialisation phase. Two kinds of disturbances can handicap HP operation: lack of GNSS observations and outages of the augmentation signal. The most serious kind of disturbance is the former. Within a few seconds the achieved convergence level is completely lost. Outages in the reception of augmentation data merely affect the relevant period of the outage - the accuracy during the outage is degraded. Only longer interruptions lead to a loss of the HP solution. When HP convergence is lost, the HP process has to be re-initialized. If there are known points (so-called “seed points”) available, a shortened “kick-start”-initialization is possible. With the aid of seed points it only takes a few minutes to restore convergence.

Mechanical design of multiple zone plates precision alignment apparatus for hard X-ray focusing in twenty-nanometer scale

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

Shu, Deming; Liu, Jie; Gleber, Sophie C.

An enhanced mechanical design of multiple zone plates precision alignment apparatus for hard x-ray focusing in a twenty-nanometer scale is provided. The precision alignment apparatus includes a zone plate alignment base frame; a plurality of zone plates; and a plurality of zone plate holders, each said zone plate holder for mounting and aligning a respective zone plate for hard x-ray focusing. At least one respective positioning stage drives and positions each respective zone plate holder. Each respective positioning stage is mounted on the zone plate alignment base frame. A respective linkage component connects each respective positioning stage and the respectivemore » zone plate holder. The zone plate alignment base frame, each zone plate holder and each linkage component is formed of a selected material for providing thermal expansion stability and positioning stability for the precision alignment apparatus.« less

Precision manometer gauge

DOEpatents

McPherson, Malcolm J.; Bellman, Robert A.

1984-01-01

A precision manometer gauge which locates a zero height and a measured height of liquid using an open tube in communication with a reservoir adapted to receive the pressure to be measured. The open tube has a reference section carried on a positioning plate which is moved vertically with machine tool precision. Double scales are provided to read the height of the positioning plate accurately, the reference section being inclined for accurate meniscus adjustment, and means being provided to accurately locate a zero or reference position.

Precision manometer gauge

DOEpatents

McPherson, M.J.; Bellman, R.A.

1982-09-27

A precision manometer gauge which locates a zero height and a measured height of liquid using an open tube in communication with a reservoir adapted to receive the pressure to be measured. The open tube has a reference section carried on a positioning plate which is moved vertically with machine tool precision. Double scales are provided to read the height of the positioning plate accurately, the reference section being inclined for accurate meniscus adjustment, and means being provided to accurately locate a zero or reference position.

Developing and implementing a high precision setup system

NASA Astrophysics Data System (ADS)

Peng, Lee-Cheng

The demand for high-precision radiotherapy (HPRT) was first implemented in stereotactic radiosurgery using a rigid, invasive stereotactic head frame. Fractionated stereotactic radiotherapy (SRT) with a frameless device was developed along a growing interest in sophisticated treatment with a tight margin and high-dose gradient. This dissertation establishes the complete management for HPRT in the process of frameless SRT, including image-guided localization, immobilization, and dose evaluation. The most ideal and precise positioning system can allow for ease of relocation, real-time patient movement assessment, high accuracy, and no additional dose in daily use. A new image-guided stereotactic positioning system (IGSPS), the Align RT3C 3D surface camera system (ART, VisionRT), which combines 3D surface images and uses a real-time tracking technique, was developed to ensure accurate positioning at the first place. The uncertainties of current optical tracking system, which causes patient discomfort due to additional bite plates using the dental impression technique and external markers, are found. The accuracy and feasibility of ART is validated by comparisons with the optical tracking and cone-beam computed tomography (CBCT) systems. Additionally, an effective daily quality assurance (QA) program for the linear accelerator and multiple IGSPSs is the most important factor to ensure system performance in daily use. Currently, systematic errors from the phantom variety and long measurement time caused by switching phantoms were discovered. We investigated the use of a commercially available daily QA device to improve the efficiency and thoroughness. Reasonable action level has been established by considering dosimetric relevance and clinic flow. As for intricate treatments, the effect of dose deviation caused by setup errors remains uncertain on tumor coverage and toxicity on OARs. The lack of adequate dosimetric simulations based on the true treatment coordinates from the treatment planning system (TPS) has limited adaptive treatments. A reliable and accurate dosimetric simulation using TPS and in-house software in uncorrected errors has been developed. In SRT, the calculated dose deviation is compared to the original treatment dose with the dose-volume histogram to investigate the dose effect of rotational errors. In summary, this work performed a quality assessment to investigate the overall accuracy of current setup systems. To reach the ideal HPRT, the reliable dosimetric simulation, an effective daily QA program and effective, precise setup systems were developed and validated.

Position measurement of the direct drive motor of Large Aperture Telescope

NASA Astrophysics Data System (ADS)

Li, Ying; Wang, Daxing

2010-07-01

Along with the development of space and astronomy science, production of large aperture telescope and super large aperture telescope will definitely become the trend. It's one of methods to solve precise drive of large aperture telescope using direct drive technology unified designed of electricity and magnetism structure. A direct drive precise rotary table with diameter of 2.5 meters researched and produced by us is a typical mechanical & electrical integration design. This paper mainly introduces position measurement control system of direct drive motor. In design of this motor, position measurement control system requires having high resolution, and precisely aligning the position of rotor shaft and making measurement, meanwhile transferring position information to position reversing information corresponding to needed motor pole number. This system has chosen high precision metal band coder and absolute type coder, processing information of coders, and has sent 32-bit RISC CPU making software processing, and gained high resolution composite coder. The paper gives relevant laboratory test results at the end, indicating the position measurement can apply to large aperture telescope control system. This project is subsidized by Chinese National Natural Science Funds (10833004).

C/EBPα induces adipogenesis through PPARγ: a unified pathway

PubMed Central

Rosen, Evan D.; Hsu, Chung-Hsin; Wang, Xinzhong; Sakai, Shuichi; Freeman, Mason W.; Gonzalez, Frank J.; Spiegelman, Bruce M.

2002-01-01

PPARγ and C/EBPα are critical transcription factors in adipogenesis, but the precise role of these proteins has been difficult to ascertain because they positively regulate each other's expression. Questions remain about whether these factors operate independently in separate, parallel pathways of differentiation, or whether a single pathway exists. PPARγ can promote adipogenesis in C/EBPα-deficient cells, but the converse has not been tested. We have created an immortalized line of fibroblasts lacking PPARγ, which we use to show that C/EBPα has no ability to promote adipogenesis in the absence of PPARγ. These results indicate that C/EBPα and PPARγ participate in a single pathway of fat cell development with PPARγ being the proximal effector of adipogenesis. PMID:11782441

Reliability of the Lactate Scout point-of-care instrument for the determination of blood L-lactate concentration in sheep.

PubMed

Kaynar, Ozgur; Karapinar, Tolga; Hayirli, Armagan; Baydar, Ersoy

2015-12-01

Data on accuracy and precision of the Lactate Scout point-of-care (POC) analyzer in ovine medicine are lacking. The purpose of the study was to assess the reliability of the Lactate Scout in sheep. Fifty-seven sheep at varying ages with various diseases were included. Blood lactate concentration in samples collected from the jugular vein was measured immediately on the Lactate Scout. Plasma L-lactate concentration was measured by the Cobas autoanalyzer as the reference method. Data were subjected to Student's t-test, Passing-Bablok regression, and Bland-Altman plot analyses for comparison and assessment of accuracy, precision, and reliability. Plasma l-lactate concentration was consistently lower than blood L-lactate concentration (3.06 ± 0.24 vs 3.3 ± 0.3 mmol/L, P < .0001). There was a positive correlation between plasma and blood L-lactate concentrations (r = .98, P < .0001). The Lactate Scout had 99% accuracy and 98% precision with the reference method. Blood (Y) and plasma (X) L-lactate concentrations were fitted to Y = 0.28 + 1.00 · X, with a residual standard deviation of 0.31 and a negligible deviation from the identity line (P = .93). The bias was fitted to Y = 0.10 + 0.05 · X, with Sy.x of 0.44 (P < .07). The Lactate Scout has high accuracy and precision, with a negligible bias. It is a reliable POC analyzer to assess L-lactate concentration in ovine medicine. © 2015 American Society for Veterinary Clinical Pathology.

Precise point positioning with the BeiDou navigation satellite system.

PubMed

Li, Min; Qu, Lizhong; Zhao, Qile; Guo, Jing; Su, Xing; Li, Xiaotao

2014-01-08

By the end of 2012, China had launched 16 BeiDou-2 navigation satellites that include six GEOs, five IGSOs and five MEOs. This has provided initial navigation and precise pointing services ability in the Asia-Pacific regions. In order to assess the navigation and positioning performance of the BeiDou-2 system, Wuhan University has built up a network of BeiDou Experimental Tracking Stations (BETS) around the World. The Position and Navigation Data Analyst (PANDA) software was modified to determine the orbits of BeiDou satellites and provide precise orbit and satellite clock bias products from the BeiDou satellite system for user applications. This article uses the BeiDou/GPS observations of the BeiDou Experimental Tracking Stations to realize the BeiDou and BeiDou/GPS static and kinematic precise point positioning (PPP). The result indicates that the precision of BeiDou static and kinematic PPP reaches centimeter level. The precision of BeiDou/GPS kinematic PPP solutions is improved significantly compared to that of BeiDou-only or GPS-only kinematic PPP solutions. The PPP convergence time also decreases with the use of combined BeiDou/GPS systems.

Precise Point Positioning with the BeiDou Navigation Satellite System

PubMed Central

Li, Min; Qu, Lizhong; Zhao, Qile; Guo, Jing; Su, Xing; Li, Xiaotao

2014-01-01

By the end of 2012, China had launched 16 BeiDou-2 navigation satellites that include six GEOs, five IGSOs and five MEOs. This has provided initial navigation and precise pointing services ability in the Asia-Pacific regions. In order to assess the navigation and positioning performance of the BeiDou-2 system, Wuhan University has built up a network of BeiDou Experimental Tracking Stations (BETS) around the World. The Position and Navigation Data Analyst (PANDA) software was modified to determine the orbits of BeiDou satellites and provide precise orbit and satellite clock bias products from the BeiDou satellite system for user applications. This article uses the BeiDou/GPS observations of the BeiDou Experimental Tracking Stations to realize the BeiDou and BeiDou/GPS static and kinematic precise point positioning (PPP). The result indicates that the precision of BeiDou static and kinematic PPP reaches centimeter level. The precision of BeiDou/GPS kinematic PPP solutions is improved significantly compared to that of BeiDou-only or GPS-only kinematic PPP solutions. The PPP convergence time also decreases with the use of combined BeiDou/GPS systems. PMID:24406856

Impact of Multi-GNSS Observations on Precise Orbit Determination and Precise Point Positioning Solutions

NASA Astrophysics Data System (ADS)

Amiri, N.; Bertiger, W. I.; Lu, W.; Miller, M. A.; David, M. W.; Ries, P.; Romans, L.; Sibois, A. E.; Sibthorpe, A.; Sakumura, C.

2017-12-01

Impact of Multi-GNSS Observations on Precise Orbit Determination and Precise Point Positioning Solutions Authors: Nikta Amiri, Willy Bertiger, Wenwen Lu, Mark Miller, David Murphy, Paul Ries, Larry Romans, Carly Sakumura, Aurore Sibois, Anthony Sibthorpe All at the Jet Propulsion Laboratory, California Institute of Technology Multiple Global Navigation Satellite Systems (GNSS) are now in various stages of completion. The four current constellations (GPS, GLONASS, BeiDou, Galileo) comprise more than 80 satellites as of July 2017, with 120 satellites expected to be available when all four constellations become fully operational. We investigate the impact of simultaneous observations to these four constellations on global network precise orbit determination (POD) solutions, and compare them to available sets of orbit and clock products submitted to the Multi-GNSS Experiment (MGEX). Using JPL's GipsyX software, we generate orbit and clock products for the four constellations. The resulting solutions are evaluated based on a number of metrics including day-to-day internal and external orbit and/or clock overlaps and estimated constellation biases. Additionally, we examine estimated station positions obtained from precise point positioning (PPP) solutions by comparing results generated from multi-GNSS and GPS-only orbit and clock products.

Target margins in radiotherapy of prostate cancer

PubMed Central

Bauman, Glenn

2016-01-01

We reviewed the literature on the use of margins in radiotherapy of patients with prostate cancer, focusing on different options for image guidance (IG) and technical issues. The search in PubMed database was limited to include studies that involved external beam radiotherapy of the intact prostate. Post-prostatectomy studies, brachytherapy and particle therapy were excluded. Each article was characterized according to the IG strategy used: positioning on external marks using room lasers, bone anatomy and soft tissue match, usage of fiducial markers, electromagnetic tracking and adapted delivery. A lack of uniformity in margin selection among institutions was evident from the review. In general, introduction of pre- and in-treatment IG was associated with smaller planning target volume (PTV) margins, but there was a lack of definitive experimental/clinical studies providing robust information on selection of exact PTV values. In addition, there is a lack of comparative research regarding the cost–benefit ratio of the different strategies: insertion of fiducial markers or electromagnetic transponders facilitates prostate gland localization but at a price of invasive procedure; frequent pre-treatment imaging increases patient in-room time, dose and labour; online plan adaptation should improve radiation delivery accuracy but requires fast and precise computation. Finally, optimal protocols for quality assurance procedures need to be established. PMID:27377353

Electromagnetic tracking (EMT) technology for improved treatment quality assurance in interstitial brachytherapy.

PubMed

Kellermeier, Markus; Herbolzheimer, Jens; Kreppner, Stephan; Lotter, Michael; Strnad, Vratislav; Bert, Christoph

2017-01-01

Electromagnetic Tracking (EMT) is a novel technique for error detection and quality assurance (QA) in interstitial high dose rate brachytherapy (HDR-iBT). The purpose of this study is to provide a concept for data acquisition developed as part of a clinical evaluation study on the use of EMT during interstitial treatment of breast cancer patients. The stability, accuracy, and precision of EMT-determined dwell positions were quantified. Dwell position reconstruction based on EMT was investigated on CT table, HDR table and PDR bed to examine the influence on precision and accuracy in a typical clinical workflow. All investigations were performed using a precise PMMA phantom. The track of catheters inserted in that phantom was measured by manually inserting a 5 degree of freedom (DoF) sensor while recording the position of three 6DoF fiducial sensors on the phantom surface to correct motion influences. From the corrected data, dwell positions were reconstructed along the catheter's track. The accuracy of the EMT-determined dwell positions was quantified by the residual distances to reference dwell positions after using a rigid registration. Precision and accuracy were investigated for different phantom-table and sensor-field generator (FG) distances. The measured precision of the EMT-determined dwell positions was ≤ 0.28 mm (95th percentile). Stability tests showed a drift of 0.03 mm in the first 20 min of use. Sudden shaking of the FG or (large) metallic objects close to the FG degrade the precision. The accuracy with respect to the reference dwell positions was on all clinical tables < 1 mm at 200 mm FG distance and 120 mm phantom-table distance. Phantom measurements showed that EMT-determined localization of dwell positions in HDR-iBT is stable, precise, and sufficiently accurate for clinical assessment. The presented method may be viable for clinical applications in HDR-iBT, like implant definition, error detection or quantification of uncertainties. Further clinical investigations are needed. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

An approach for filtering hyperbolically positioned underwater acoustic telemetry data with position precision estimates

USGS Publications Warehouse

Meckley, Trevor D.; Holbrook, Christopher M.; Wagner, C. Michael; Binder, Thomas R.

2014-01-01

The use of position precision estimates that reflect the confidence in the positioning process should be considered prior to the use of biological filters that rely on a priori expectations of the subject’s movement capacities and tendencies. Position confidence goals should be determined based upon the needs of the research questions and analysis requirements versus arbitrary selection, in which filters of previous studies are adopted. Data filtering with this approach ensures that data quality is sufficient for the selected analyses and presents the opportunity to adjust or identify a different analysis in the event that the requisite precision was not attained. Ignoring these steps puts a practitioner at risk of reporting errant findings.

Accuracy and Precision of a Veterinary Neuronavigation System for Radiation Oncology Positioning

PubMed Central

Ballegeer, Elizabeth A.; Frey, Stephen; Sieffert, Rob

2018-01-01

Conformal radiation treatment plans such as IMRT and other radiosurgery techniques require very precise patient positioning, typically within a millimeter of error for best results. CT cone beam, real-time navigation, and infrared position sensors are potential options for success but rarely present in veterinary radiation centers. A neuronavigation system (Brainsight Vet, Rogue Research) was tested 22 times on a skull for positioning accuracy and precision analysis. The first 6 manipulations allowed the authors to become familiar with the system but were still included in the analyses. Overall, the targeting mean error in 3D was 1.437 mm with SD 1.242 mm. This system could be used for positioning for radiation therapy or radiosurgery. PMID:29666822

Clinical performance of dental fiberscope image guided system for endodontic treatment.

PubMed

Yamazaki, Yasushi; Ogawa, Takumi; Shigeta, Yuko; Ikawa, Tomoko; Kasama, Shintaro; Hattori, Asaki; Suzuki, Naoki; Yamamoto, Takatsugu; Ozawa, Toshiko; Arai, Takashi

2011-01-01

We developed a dental fiberscope that can be navigated. As a result we are able to better grasp the device position relative to the teeth, aiming at the lesion more precisely. However, the device position and the precise target setting were difficult to consistently ascertain. The aim of this study is to navigate the position of tip of the dental fiberscope fiber in the root canal with our navigation system. A 3D tooth model was made from the raw dental CT data. In addition, the optical position of the measurement device, OPTOTRAK system was used for registration of the 3D model and actual teeth position and to chase the scope movement. We developed exclusive software to unify information. We were subsequently able to precisely indicate the relation of the position between the device and the teeth on the 3D model in the monitor. This allowed us to aim at the lesion more precisely, as the revised endoscopic image matched the 3D model. The application of this endoscopic navigation system could increase the success rate for root canal treatments with recalcitrant lesion.

[Spirograph for small laboratory animals].

PubMed

Daniiarov, S B; Lanskiĭ, Iu M; Bebinov, E M

1986-10-01

A design of dry spirograph is described. It is characterized by greater precision, lack of inertia, high reliability, absence of respiration resistance, adequate form of recording, rapid resetting to any respiratory rate. The device consists of two similar injection syringes, photoelectric sensor for the identification of the initial moments of respiration stages, electromagnetic valves, two photoelectric converters of the air volume into the impulse signal, vacuum micro-pump, microcompressor and a system of air-driving tubes. In the initial position of pistons and valves the microcompressor pumps air into the inhalation cylinder and lifts the piston to the upper extreme position. With the signal marking the beginning of inspiration, the valves switch over and the piston lowers, pushing out the air, which moves into the animals' respiratory organs. Simultaneously, the signals of the inhaled air volume from the photoelectric transducer reach the recorder. During expiration the air pushes the piston down into the second cylinder and photoelectric transducer gives the information on the volume of the expired air.

Mitochondrial Dynamics Mediated by Mitofusin 1 Is Required for POMC Neuron Glucose-Sensing and Insulin Release Control.

PubMed

Ramírez, Sara; Gómez-Valadés, Alicia G; Schneeberger, Marc; Varela, Luis; Haddad-Tóvolli, Roberta; Altirriba, Jordi; Noguera, Eduard; Drougard, Anne; Flores-Martínez, Álvaro; Imbernón, Mónica; Chivite, Iñigo; Pozo, Macarena; Vidal-Itriago, Andrés; Garcia, Ainhoa; Cervantes, Sara; Gasa, Rosa; Nogueiras, Ruben; Gama-Pérez, Pau; Garcia-Roves, Pablo M; Cano, David A; Knauf, Claude; Servitja, Joan-Marc; Horvath, Tamas L; Gomis, Ramon; Zorzano, Antonio; Claret, Marc

2017-06-06

Proopiomelanocortin (POMC) neurons are critical sensors of nutrient availability implicated in energy balance and glucose metabolism control. However, the precise mechanisms underlying nutrient sensing in POMC neurons remain incompletely understood. We show that mitochondrial dynamics mediated by Mitofusin 1 (MFN1) in POMC neurons couple nutrient sensing with systemic glucose metabolism. Mice lacking MFN1 in POMC neurons exhibited defective mitochondrial architecture remodeling and attenuated hypothalamic gene expression programs during the fast-to-fed transition. This loss of mitochondrial flexibility in POMC neurons bidirectionally altered glucose sensing, causing abnormal glucose homeostasis due to defective insulin secretion by pancreatic β cells. Fed mice lacking MFN1 in POMC neurons displayed enhanced hypothalamic mitochondrial oxygen flux and reactive oxygen species generation. Central delivery of antioxidants was able to normalize the phenotype. Collectively, our data posit MFN1-mediated mitochondrial dynamics in POMC neurons as an intrinsic nutrient-sensing mechanism and unveil an unrecognized link between this subset of neurons and insulin release. Copyright © 2017 Elsevier Inc. All rights reserved.

New high precision U-Pb calibration of the late Early-Triassic (Smithian-Spathian Boundary, South China)

NASA Astrophysics Data System (ADS)

Widmann, Philipp; Leu, Marc; Goudemand, Nicolas; Schaltegger, Urs; Bucher, Hugo

2017-04-01

Following the Permian-Triassic mass extinction (PTME), the Early Triassic is characterized by large short-lived perturbations of the global carbon cycle associated with radiation and extinction pulses of the biota. More stable conditions resumed in the Middle Triassic (Anisian). The exact ages and duration of these short-lived but intense radiation-extinction events as well as carbon cycle perturbations are poorly constrained and a robust intercalibration of U-Pb dates, biochronozones and carbon isotope fluctuations is still lacking. An accurate and precise time frame is essential in order to quantify the dynamics of the underlying mechanistic processes and to assess the validity of the various explanatory scenarios. The most drastic Early Triassic extinction occurred at the Smithian-Spathian boundary (SSB) and is associated with a globally recognized sharp positive excursion of the marine d13C signal. Based on the most recently published ages for the Permian-Triassic boundary (251.938 ± 0.029 Ma, Baresel et al., 2016) and for the Early-Middle Triassic boundary (247.05 ± 0.16 Ma, Ovtcharova et al., 2015), we know the Early Triassic lasted 4.9 myr. However, neither the position of the SSB nor the durations of the major biotic and abiotic events around the SSB are constrained by radiometric dates. Here, we will present new high precision, chemical abrasion, isotope dilution, thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb ages from single zircon crystals, sampled from closely spaced volcanic ash layers that bracket the SSB in the Nanpanjiang Basin (Guizhou province, South China). These ash layers are found in a mixed carbonate-siliciclastic, conodont-rich sedimentary succession (Luolou Formation) that is well calibrated biochronologically. We obtained best estimates of the ages of the SSB and associated events by applying Bayesian age modelling. References: Baresel, B., Bucher, H., Brosse, M., Cordey, F., Guodun, K., and Schaltegger, U., 2016. Precise age for the Permian-Triassic boundary in South China from high precision U-Pb geochronology and Bayesian age-depth modelling: Solid Earth Discussions, doi: 10 .5194 /se -2016 -145. Ovtcharova, M., Goudemand, N., Hammer, O., Guodun, K., Cordey, F., Galfetti, T., Schaltegger, U. and Bucher, H. 2015. Developing a strategy for accurate definition of a geological boundary through radio-isotopic and biochronological dating: the Early-Middle Triassic boundary (South China). Earth-Science Reviews, 146, 65-76.

Robotic-Arm Assisted Total Knee Arthroplasty Demonstrated Greater Accuracy and Precision to Plan Compared with Manual Techniques.

PubMed

Hampp, Emily L; Chughtai, Morad; Scholl, Laura Y; Sodhi, Nipun; Bhowmik-Stoker, Manoshi; Jacofsky, David J; Mont, Michael A

2018-05-01

This study determined if robotic-arm assisted total knee arthroplasty (RATKA) allows for more accurate and precise bone cuts and component position to plan compared with manual total knee arthroplasty (MTKA). Specifically, we assessed the following: (1) final bone cuts, (2) final component position, and (3) a potential learning curve for RATKA. On six cadaver specimens (12 knees), a MTKA and RATKA were performed on the left and right knees, respectively. Bone-cut and final-component positioning errors relative to preoperative plans were compared. Median errors and standard deviations (SDs) in the sagittal, coronal, and axial planes were compared. Median values of the absolute deviation from plan defined the accuracy to plan. SDs described the precision to plan. RATKA bone cuts were as or more accurate to plan based on nominal median values in 11 out of 12 measurements. RATKA bone cuts were more precise to plan in 8 out of 12 measurements ( p  ≤ 0.05). RATKA final component positions were as or more accurate to plan based on median values in five out of five measurements. RATKA final component positions were more precise to plan in four out of five measurements ( p  ≤ 0.05). Stacked error results from all cuts and implant positions for each specimen in procedural order showed that RATKA error was less than MTKA error. Although this study analyzed a small number of cadaver specimens, there were clear differences that separated these two groups. When compared with MTKA, RATKA demonstrated more accurate and precise bone cuts and implant positioning to plan. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Precise CCD positions of Himalia using Gaia DR1 in 2015-2016

NASA Astrophysics Data System (ADS)

Peng, H. W.; Peng, Q. Y.; Wang, N.

2017-05-01

In order to obtain high-precision CCD positions of Himalia, the sixth Jovian satellite, a total of 598 CCD observations have been obtained during the years 2015-2016. The observations were made by using the 2.4 and 1 m telescopes administered by Yunnan Observatories over 27 nights. Several factors that would influence the positional precision of Himalia were analysed, including the reference star catalogue used, the geometric distortion and the phase effect. By taking advantage of its unprecedented positional precision, the recently released catalogue Gaia Data Release 1 was chosen to match reference stars in the CCD frames of both Himalia and open clusters, which were observed for deriving the geometric distortion. The latest version of sofa library was used to calculate the positions of reference stars. The theoretical positions of Himalia were retrieved from the Jet Propulsion Laboratory Horizons System that includes the satellite ephemeris JUP300, while the positions of Jupiter were based on the planetary ephemeris DE431. Our results showed that the means of observed minus computed (O - C) residuals are 0.071 and -0.001 arcsec in right ascension and declination, respectively. Their standard deviations are estimated at about 0.03 arcsec in each direction.

Subtracting the sequence bias from partially digested MNase-seq data reveals a general contribution of TFIIS to nucleosome positioning.

PubMed

Gutiérrez, Gabriel; Millán-Zambrano, Gonzalo; Medina, Daniel A; Jordán-Pla, Antonio; Pérez-Ortín, José E; Peñate, Xenia; Chávez, Sebastián

2017-12-07

TFIIS stimulates RNA cleavage by RNA polymerase II and promotes the resolution of backtracking events. TFIIS acts in the chromatin context, but its contribution to the chromatin landscape has not yet been investigated. Co-transcriptional chromatin alterations include subtle changes in nucleosome positioning, like those expected to be elicited by TFIIS, which are elusive to detect. The most popular method to map nucleosomes involves intensive chromatin digestion by micrococcal nuclease (MNase). Maps based on these exhaustively digested samples miss any MNase-sensitive nucleosomes caused by transcription. In contrast, partial digestion approaches preserve such nucleosomes, but introduce noise due to MNase sequence preferences. A systematic way of correcting this bias for massively parallel sequencing experiments is still missing. To investigate the contribution of TFIIS to the chromatin landscape, we developed a refined nucleosome-mapping method in Saccharomyces cerevisiae. Based on partial MNase digestion and a sequence-bias correction derived from naked DNA cleavage, the refined method efficiently mapped nucleosomes in promoter regions rich in MNase-sensitive structures. The naked DNA correction was also important for mapping gene body nucleosomes, particularly in those genes whose core promoters contain a canonical TATA element. With this improved method, we analyzed the global nucleosomal changes caused by lack of TFIIS. We detected a general increase in nucleosomal fuzziness and more restricted changes in nucleosome occupancy, which concentrated in some gene categories. The TATA-containing genes were preferentially associated with decreased occupancy in gene bodies, whereas the TATA-like genes did so with increased fuzziness. The detected chromatin alterations correlated with functional defects in nascent transcription, as revealed by genomic run-on experiments. The combination of partial MNase digestion and naked DNA correction of the sequence bias is a precise nucleosomal mapping method that does not exclude MNase-sensitive nucleosomes. This method is useful for detecting subtle alterations in nucleosome positioning produced by lack of TFIIS. Their analysis revealed that TFIIS generally contributed to nucleosome positioning in both gene promoters and bodies. The independent effect of lack of TFIIS on nucleosome occupancy and fuzziness supports the existence of alternative chromatin dynamics during transcription elongation.

Design and algorithm research of high precision airborne infrared touch screen

NASA Astrophysics Data System (ADS)

Zhang, Xiao-Bing; Wang, Shuang-Jie; Fu, Yan; Chen, Zhao-Quan

2016-10-01

There are shortcomings of low precision, touch shaking, and sharp decrease of touch precision when emitting and receiving tubes are failure in the infrared touch screen. A high precision positioning algorithm based on extended axis is proposed to solve these problems. First, the unimpeded state of the beam between emitting and receiving tubes is recorded as 0, while the impeded state is recorded as 1. Then, the method of oblique scan is used, in which the light of one emitting tube is used for five receiving tubes. The impeded information of all emitting and receiving tubes is collected as matrix. Finally, according to the method of arithmetic average, the position of the touch object is calculated. The extended axis positioning algorithm is characteristic of high precision in case of failure of individual infrared tube and affects slightly the precision. The experimental result shows that the 90% display area of the touch error is less than 0.25D, where D is the distance between adjacent emitting tubes. The conclusion is gained that the algorithm based on extended axis has advantages of high precision, little impact when individual infrared tube is failure, and using easily.

Measurable residual disease testing in acute myeloid leukaemia.

PubMed

Hourigan, C S; Gale, R P; Gormley, N J; Ossenkoppele, G J; Walter, R B

2017-07-01

There is considerable interest in developing techniques to detect and/or quantify remaining leukaemia cells termed measurable or, less precisely, minimal residual disease (MRD) in persons with acute myeloid leukaemia (AML) in complete remission defined by cytomorphological criteria. An important reason for AML MRD-testing is the possibility of estimating the likelihood (and timing) of leukaemia relapse. A perfect MRD-test would precisely quantify leukaemia cells biologically able and likely to cause leukaemia relapse within a defined interval. AML is genetically diverse and there is currently no uniform approach to detecting such cells. Several technologies focused on immune phenotype or cytogenetic and/or molecular abnormalities have been developed, each with advantages and disadvantages. Many studies report a positive MRD-test at diverse time points during AML therapy identifies persons with a higher risk of leukaemia relapse compared with those with a negative MRD-test even after adjusting for other prognostic and predictive variables. No MRD-test in AML has perfect sensitivity and specificity for relapse prediction at the cohort- or subject levels and there are substantial rates of false-positive and -negative tests. Despite these limitations, correlations between MRD-test results and relapse risk have generated interest in MRD-test result-directed therapy interventions. However, convincing proof that a specific intervention will reduce relapse risk in persons with a positive MRD-test is lacking and needs testing in randomized trials. Routine clinical use of MRD-testing requires further refinements and standardization/harmonization of assay platforms and results reporting. Such data are needed to determine whether results of MRD-testing can be used as a surrogate end point in AML therapy trials. This could make drug-testing more efficient and accelerate regulatory approvals. Although MRD-testing in AML has advanced substantially, much remains to be done.

Interference techniques in fluorescence microscopy

NASA Astrophysics Data System (ADS)

Dogan, Mehmet

We developed a set of interference-based optical microscopy techniques to study biological structures through nanometer-scale axial localization of fluorescent biomarkers. Spectral self-interference fluorescence microscopy (SSFM) utilizes interference of direct and reflected waves emitted from fluorescent molecules in the vicinity of planar reflectors to reveal the axial position of the molecules. A comprehensive calculation algorithm based on Green's function formalism is presented to verify the validity of approximations used in a far-field approach that describes the emission of fluorescent markers near interfaces. Using the validated model, theoretical limits of axial localization were determined with emphasis given to numerical aperture (NA) dependence of localization uncertainty. SSFM was experimentally demonstrated in conformational analysis of nucleoproteins. In particular, interaction between surface-tethered 75-mer double strand DNA and integration host factor (IHF) protein was probed on Si-SiO2 substrates by determining the axial position of fluorescent labels attached to the free ends of DNA molecules. Despite its sub-nanometer precision axial localization capability, SSFM lacks high lateral resolution due to the low-NA requirement for planar reflectors. We developed a second technique, 4Pi-SSFM, which improves the lateral resolution of a conventional SSFM system by an order of magnitude while achieving nanometer-scale axial localization precision. Using two opposing high-NA objectives, fluorescence signal is interferometrically collected and spectral interference pattern is recorded. Axial position of emitters is found from analysis of the spectra. The 4Pi-SSFM technique was experimentally demonstrated by determining the surface profiles of fabricated glass surfaces and outer membranes of Shigella, a type of Gram-negative bacteria. A further discussion is presented to localize surface O antigen, which is an important oligosaccharide structure in the virulence mechanism of the Gram-negative bacteria, including E. coli and Shigella.

Novel linear piezoelectric motor for precision position stage

NASA Astrophysics Data System (ADS)

Chen, Chao; Shi, Yunlai; Zhang, Jun; Wang, Junshan

2016-03-01

Conventional servomotor and stepping motor face challenges in nanometer positioning stages due to the complex structure, motion transformation mechanism, and slow dynamic response, especially directly driven by linear motor. A new butterfly-shaped linear piezoelectric motor for linear motion is presented. A two-degree precision position stage driven by the proposed linear ultrasonic motor possesses a simple and compact configuration, which makes the system obtain shorter driving chain. Firstly, the working principle of the linear ultrasonic motor is analyzed. The oscillation orbits of two driving feet on the stator are produced successively by using the anti-symmetric and symmetric vibration modes of the piezoelectric composite structure, and the slider pressed on the driving feet can be propelled twice in only one vibration cycle. Then with the derivation of the dynamic equation of the piezoelectric actuator and transient response model, start-upstart-up and settling state characteristics of the proposed linear actuator is investigated theoretically and experimentally, and is applicable to evaluate step resolution of the precision platform driven by the actuator. Moreover the structure of the two-degree position stage system is described and a special precision displacement measurement system is built. Finally, the characteristics of the two-degree position stage are studied. In the closed-loop condition the positioning accuracy of plus or minus <0.5 μm is experimentally obtained for the stage propelled by the piezoelectric motor. A precision position stage based the proposed butterfly-shaped linear piezoelectric is theoretically and experimentally investigated.

Developing the Pieta House Suicide Intervention Model: a quasi-experimental, repeated measures design.

PubMed

Surgenor, Paul Wg; Freeman, Joan; O'Connor, Cindy

2015-01-01

While most crisis intervention models adhere to a generalised theoretical framework, the lack of clarity around how these should be enacted has resulted in a proliferation of models, most of which have little to no empirical support. The primary aim of this research was to propose a suicide intervention model that would resolve the client's suicidal crisis by decreasing their suicidal ideation and improve their outlook through enhancing a range of protective factors. The secondary aim was to assess the impact of this model on negative and positive outlook. A quasi-experimental, pre-test post-test repeated measures design was employed. A questionnaire assessing self-esteem, depression, and positive and negative suicidal ideation was administered to the same participants pre- and post- therapy facilitating paired responses. Multiple analysis of variance and paired-samples t-tests were conducted to establish whether therapy using the PH-SIM had a significant effect on the clients' negative and positive outlook. Analyses revealed a statistically significant effect of therapy for depression, negative suicidal ideation, self-esteem, and positive suicidal ideation. Negative outlook was significantly lower after therapy and positive outlook significantly higher. The decreased negative outlook and increased positive outlook following therapy provide some support for the proposed model in fulfilling its role, though additional research is required to establish the precise role of the intervention model in achieving this.

Seamless Genome Editing in Rice via Gene Targeting and Precise Marker Elimination.

PubMed

Nishizawa-Yokoi, Ayako; Saika, Hiroaki; Toki, Seiichi

2016-01-01

Positive-negative selection using hygromycin phosphotransferase (hpt) and diphtheria toxin A-fragment (DT-A) as positive and negative selection markers, respectively, allows enrichment of cells harboring target genes modified via gene targeting (GT). We have developed a successful GT system employing positive-negative selection and subsequent precise marker excision via the piggyBac transposon derived from the cabbage looper moth to introduce desired modifications into target genes in the rice genome. This approach could be applied to the precision genome editing of almost all endogenous genes throughout the genome, at least in rice.

Experimental Study on the Precise Orbit Determination of the BeiDou Navigation Satellite System

PubMed Central

He, Lina; Ge, Maorong; Wang, Jiexian; Wickert, Jens; Schuh, Harald

2013-01-01

The regional service of the Chinese BeiDou satellite navigation system is now in operation with a constellation including five Geostationary Earth Orbit satellites (GEO), five Inclined Geosynchronous Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites. Besides the standard positioning service with positioning accuracy of about 10 m, both precise relative positioning and precise point positioning are already demonstrated. As is well known, precise orbit and clock determination is essential in enhancing precise positioning services. To improve the satellite orbits of the BeiDou regional system, we concentrate on the impact of the tracking geometry and the involvement of MEOs, and on the effect of integer ambiguity resolution as well. About seven weeks of data collected at the BeiDou Experimental Test Service (BETS) network is employed in this experimental study. Several tracking scenarios are defined, various processing schemata are designed and carried out; and then, the estimates are compared and analyzed in detail. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. The involvement of MEOs and ambiguity-fixing also make the orbits better. PMID:23529116

Experimental study on the precise orbit determination of the BeiDou navigation satellite system.

PubMed

He, Lina; Ge, Maorong; Wang, Jiexian; Wickert, Jens; Schuh, Harald

2013-03-01

The regional service of the Chinese BeiDou satellite navigation system is now in operation with a constellation including five Geostationary Earth Orbit satellites (GEO), five Inclined Geosynchronous Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites. Besides the standard positioning service with positioning accuracy of about 10 m, both precise relative positioning and precise point positioning are already demonstrated. As is well known, precise orbit and clock determination is essential in enhancing precise positioning services. To improve the satellite orbits of the BeiDou regional system, we concentrate on the impact of the tracking geometry and the involvement of MEOs, and on the effect of integer ambiguity resolution as well. About seven weeks of data collected at the BeiDou Experimental Test Service (BETS) network is employed in this experimental study. Several tracking scenarios are defined, various processing schemata are designed and carried out; and then, the estimates are compared and analyzed in detail. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. The involvement of MEOs and ambiguity-fixing also make the orbits better.

Horizon Based Orientation Estimation for Planetary Surface Navigation

NASA Technical Reports Server (NTRS)

Bouyssounouse, X.; Nefian, A. V.; Deans, M.; Thomas, A.; Edwards, L.; Fong, T.

2016-01-01

Planetary rovers navigate in extreme environments for which a Global Positioning System (GPS) is unavailable, maps are restricted to relatively low resolution provided by orbital imagery, and compass information is often lacking due to weak or not existent magnetic fields. However, an accurate rover localization is particularly important to achieve the mission success by reaching the science targets, avoiding negative obstacles visible only in orbital maps, and maintaining good communication connections with ground. This paper describes a horizon solution for precise rover orientation estimation. The detected horizon in imagery provided by the on board navigation cameras is matched with the horizon rendered over the existing terrain model. The set of rotation parameters (roll, pitch yaw) that minimize the cost function between the two horizon curves corresponds to the rover estimated pose.

Refine of Regional Ocean Tide Model Using GPS Data

NASA Astrophysics Data System (ADS)

Wang, F.; Zhang, P.; Sun, Z.; Jiang, Z.; Zhang, Q.

2018-04-01

Due to lack of regional data constraints, all global ocean tide models are not accuracy enough in offshore areas around China, also the displacements predicted by different models are not consistency. The ocean tide loading effects have become a major source of error in the high precision GPS positioning. It is important for high precision GPS applications to build an appropriate regional ocean tide model. We first process the four offshore GPS tracking station's observation data which located in Guangdong province of China by using PPP aproach to get the time series. Then use the spectral inversion method to acquire eigenvalues of the Ocean Tidal Loading. We get the estimated value of not only 12hour period tide wave (M2, S2, N2, K2) but also 24hour period tide wave (O1, K1, P1, Q1) which has not been got in presious studies. The contrast test shows that GPS estimation value of M2, K1 is consistent with the result of five famous glocal ocean load tide models, but S2, N2, K2, O1, P1, Q1 is obviously larger.

Synthetic Capillaries to Control Microscopic Blood Flow.

PubMed

Sarveswaran, K; Kurz, V; Dong, Z; Tanaka, T; Penny, S; Timp, G

2016-02-24

Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using "live cell lithography"(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision-no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100-1000 cells, organized hierarchically to express a predictable function.

Ion source for high-precision mass spectrometry

DOEpatents

Todd, Peter J.; McKown, Henry S.; Smith, David H.

1984-01-01

The invention is directed to a method for increasing the precision of positive-ion relative abundance measurements conducted in a sector mass spectrometer having an ion source for directing a beam of positive ions onto a collimating slit. The method comprises incorporating in the source an electrostatic lens assembly for providing a positive-ion beam of circular cross section for collimation by the slit.

Precision enhancement of pavement roughness localization with connected vehicles

NASA Astrophysics Data System (ADS)

Bridgelall, R.; Huang, Y.; Zhang, Z.; Deng, F.

2016-02-01

Transportation agencies rely on the accurate localization and reporting of roadway anomalies that could pose serious hazards to the traveling public. However, the cost and technical limitations of present methods prevent their scaling to all roadways. Connected vehicles with on-board accelerometers and conventional geospatial position receivers offer an attractive alternative because of their potential to monitor all roadways in real-time. The conventional global positioning system is ubiquitous and essentially free to use but it produces impractically large position errors. This study evaluated the improvement in precision achievable by augmenting the conventional geo-fence system with a standard speed bump or an existing anomaly at a pre-determined position to establish a reference inertial marker. The speed sensor subsequently generates position tags for the remaining inertial samples by computing their path distances relative to the reference position. The error model and a case study using smartphones to emulate connected vehicles revealed that the precision in localization improves from tens of metres to sub-centimetre levels, and the accuracy of measuring localized roughness more than doubles. The research results demonstrate that transportation agencies will benefit from using the connected vehicle method to achieve precision and accuracy levels that are comparable to existing laser-based inertial profilers.

Ion chromatography for the precise analysis of chloride and sodium in sweat for the diagnosis of cystic fibrosis.

PubMed

Doorn, J; Storteboom, T T R; Mulder, A M; de Jong, W H A; Rottier, B L; Kema, I P

2015-07-01

Measurement of chloride in sweat is an essential part of the diagnostic algorithm for cystic fibrosis. The lack in sensitivity and reproducibility of current methods led us to develop an ion chromatography/high-performance liquid chromatography (IC/HPLC) method, suitable for the analysis of both chloride and sodium in small volumes of sweat. Precision, linearity and limit of detection of an in-house developed IC/HPLC method were established. Method comparison between the newly developed IC/HPLC method and the traditional Chlorocounter was performed, and trueness was determined using Passing Bablok method comparison with external quality assurance material (Royal College of Pathologists of Australasia). Precision and linearity fulfill criteria as established by UK guidelines are comparable with inductively coupled plasma-mass spectrometry methods. Passing Bablok analysis demonstrated excellent correlation between IC/HPLC measurements and external quality assessment target values, for both chloride and sodium. With a limit of quantitation of 0.95 mmol/L, our method is suitable for the analysis of small amounts of sweat and can thus be used in combination with the Macroduct collection system. Although a chromatographic application results in a somewhat more expensive test compared to a Chlorocounter test, more accurate measurements are achieved. In addition, simultaneous measurements of sodium concentrations will result in better detection of false positives, less test repeating and thus faster and more accurate and effective diagnosis. The described IC/HPLC method, therefore, provides a precise, relatively cheap and easy-to-handle application for the analysis of both chloride and sodium in sweat. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

High-precision relative position and attitude measurement for on-orbit maintenance of spacecraft

NASA Astrophysics Data System (ADS)

Zhu, Bing; Chen, Feng; Li, Dongdong; Wang, Ying

2018-02-01

In order to realize long-term on-orbit running of satellites, space stations, etc spacecrafts, in addition to the long life design of devices, The life of the spacecraft can also be extended by the on-orbit servicing and maintenance. Therefore, it is necessary to keep precise and detailed maintenance of key components. In this paper, a high-precision relative position and attitude measurement method used in the maintenance of key components is given. This method mainly considers the design of the passive cooperative marker, light-emitting device and high resolution camera in the presence of spatial stray light and noise. By using a series of algorithms, such as background elimination, feature extraction, position and attitude calculation, and so on, the high precision relative pose parameters as the input to the control system between key operation parts and maintenance equipment are obtained. The simulation results show that the algorithm is accurate and effective, satisfying the requirements of the precision operation technique.

Detection of epileptic seizure in EEG signals using linear least squares preprocessing.

PubMed

Roshan Zamir, Z

2016-09-01

An epileptic seizure is a transient event of abnormal excessive neuronal discharge in the brain. This unwanted event can be obstructed by detection of electrical changes in the brain that happen before the seizure takes place. The automatic detection of seizures is necessary since the visual screening of EEG recordings is a time consuming task and requires experts to improve the diagnosis. Much of the prior research in detection of seizures has been developed based on artificial neural network, genetic programming, and wavelet transforms. Although the highest achieved accuracy for classification is 100%, there are drawbacks, such as the existence of unbalanced datasets and the lack of investigations in performances consistency. To address these, four linear least squares-based preprocessing models are proposed to extract key features of an EEG signal in order to detect seizures. The first two models are newly developed. The original signal (EEG) is approximated by a sinusoidal curve. Its amplitude is formed by a polynomial function and compared with the predeveloped spline function. Different statistical measures, namely classification accuracy, true positive and negative rates, false positive and negative rates and precision, are utilised to assess the performance of the proposed models. These metrics are derived from confusion matrices obtained from classifiers. Different classifiers are used over the original dataset and the set of extracted features. The proposed models significantly reduce the dimension of the classification problem and the computational time while the classification accuracy is improved in most cases. The first and third models are promising feature extraction methods with the classification accuracy of 100%. Logistic, LazyIB1, LazyIB5, and J48 are the best classifiers. Their true positive and negative rates are 1 while false positive and negative rates are 0 and the corresponding precision values are 1. Numerical results suggest that these models are robust and efficient for detecting epileptic seizure. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Where in the world are my field plots? Using GPS effectively in environmental field studies

USGS Publications Warehouse

Johnson, Chris E.; Barton, Christopher C.

2004-01-01

Global positioning system (GPS) technology is rapidly replacing tape, compass, and traditional surveying instruments as the preferred tool for estimating the positions of environmental research sites. One important problem, however, is that it can be difficult to estimate the uncertainty of GPS-derived positions. Sources of error include various satellite- and site-related factors, such as forest canopy and topographic obstructions. In a case study from the Hubbard Brook Experimental Forest in New Hampshire, hand-held, mapping-grade GPS receivers generally estimated positions with 1–5 m precision in open, unobstructed settings, and 20–30 m precision under forest canopy. Surveying-grade receivers achieved precisions of 10 cm or less, even in challenging terrain. Users can maximize the quality of their GPS measurements by “mission planning” to take advantage of high-quality satellite conditions. Repeated measurements and simultaneous data collection at multiple points can be used to assess accuracy and precision.

Analysis of the influence of a metha-type metaphysical stem on biomechanical parameters.

PubMed

Pozowski, Andrzej; Ścigała, Krzysztof; Kierzek, Andrzej; Paprocka-Borowicz, Małgorzata; Kuciel-Lewandowska, Jadwiga

2013-01-01

The full postoperative loading of the limb is possible if patients are properly selected and qualified for hip arthroplasty and the requirements as to the proper position of the metaphysial stem are met. The lack of precision, and patient qualification which does not satisfy the fixed criteria may result in stem setting inconsistent with the assumptions. An analysis based on the finite element method (FEM) will enable one to find out how to plan the magnitude of operated joint loading on the basis of the position of the stem in the postoperative radiograph. By analyzing the distribution of bone tissue deformations one can identify the zones where the spongy bone is overloaded and determine the strain level in comparison with the one determined for a model of the bone with the stem in proper position. On the basis of the results obtained one can estimate the range of loads for the operated limb, which will not result in the loss of the stem's primary stability prior to obtaining secondary stability through osteointegration. Moreover, an analysis of the formation of bone structures around the stem showed that the incorrect setting of a Metha-type stem may lead to the initiation of loosening.

MINOS Timing and GPS Precise Point Positioning

DTIC Science & Technology

2012-01-01

Minos Timing Spec • Neutrinos created in bunches separated by 19 ns • ~ 1 neutrino/day detected in Soudan Mine – 2 milliseconds travel time...calibration – No low-cost Fermilab to Soudan Mine connections known – Not yet tested for operational time transfer Clock Options • High-Performance... UNDERGROUND LABORATORY •;, ~ (((ft.F ~’: · GPS PRECISE POINT POSITIONING A Brief Overview What is GPS PPP? • GPS PPP is a way to use precise ephemerides

Analysis of RDSS positioning accuracy based on RNSS wide area differential technique

NASA Astrophysics Data System (ADS)

Xing, Nan; Su, RanRan; Zhou, JianHua; Hu, XiaoGong; Gong, XiuQiang; Liu, Li; He, Feng; Guo, Rui; Ren, Hui; Hu, GuangMing; Zhang, Lei

2013-10-01

The BeiDou Navigation Satellite System (BDS) provides Radio Navigation Service System (RNSS) as well as Radio Determination Service System (RDSS). RDSS users can obtain positioning by responding the Master Control Center (MCC) inquiries to signal transmitted via GEO satellite transponder. The positioning result can be calculated with elevation constraint by MCC. The primary error sources affecting the RDSS positioning accuracy are the RDSS signal transceiver delay, atmospheric trans-mission delay and GEO satellite position error. During GEO orbit maneuver, poor orbit forecast accuracy significantly impacts RDSS services. A real-time 3-D orbital correction method based on wide-area differential technique is raised to correct the orbital error. Results from the observation shows that the method can successfully improve positioning precision during orbital maneuver, independent from the RDSS reference station. This improvement can reach 50% in maximum. Accurate calibration of the RDSS signal transceiver delay precision and digital elevation map may have a critical role in high precise RDSS positioning services.

Laminated magnet field coil sheath

DOEpatents

Skaritka, John R.

1987-12-01

a method for manufacturing a magnet cable trim coil in a sheath assembly for use in a cryogenic particle accelerator. A precisely positioned pattern of trim coil turns is bonded to a flexible substrate sheath that is capable of withstanding cryogenic operating conditions. In the method of the invention the flexible sheath, with the trim coil pattern precisely positioned thereon, is accurately positioned at a precise location relative to a bore tube assembly of an accelerator and is then bonded to the bore tube with a tape suitable for cryogenic application. The resultant assembly can be readily handled and installed within an iron magnet yoke assembly of a suitable cryogenic particle accelerator.

A theoretical study on the bottlenecks of GPS phase ambiguity resolution in a CORS RTK Network

NASA Astrophysics Data System (ADS)

Odijk, D.; Teunissen, P.

2011-01-01

Crucial to the performance of GPS Network RTK positioning is that a user receives and applies correction information from a CORS Network. These corrections are necessary for the user to account for the atmospheric (ionospheric and tropospheric) delays and possibly orbit errors between his approximate location and the locations of the CORS Network stations. In order to provide the most precise corrections to users, the CORS Network processing should be based on integer resolution of the carrier phase ambiguities between the network's CORS stations. One of the main challenges is to reduce the convergence time, thus being able to quickly resolve the integer carrier phase ambiguities between the network's reference stations. Ideally, the network ambiguity resolution should be conducted within one single observation epoch, thus truly in real time. Unfortunately, single-epoch CORS Network RTK ambiguity resolution is currently not feasible and in the present contribution we study the bottlenecks preventing this. For current dual-frequency GPS the primary cause of these CORS Network integer ambiguity initialization times is the lack of a sufficiently large number of visible satellites. Although an increase in satellite number shortens the ambiguity convergence times, instantaneous CORS Network RTK ambiguity resolution is not feasible even with 14 satellites. It is further shown that increasing the number of stations within the CORS Network itself does not help ambiguity resolution much, since every new station introduces new ambiguities. The problem with CORS Network RTK ambiguity resolution is the presence of the atmospheric (mainly ionospheric) delays themselves and the fact that there are no external corrections that are sufficiently precise. We also show that external satellite clock corrections hardly contribute to CORS Network RTK ambiguity resolution, despite their quality, since the network satellite clock parameters and the ambiguities are almost completely uncorrelated. One positive is that the foreseen modernized GPS will have a very beneficial effect on CORS ambiguity resolution, because of an additional frequency with improved code precision.

Improved Controller for a Three-Axis Piezoelectric Stage

NASA Technical Reports Server (NTRS)

Rao, Shanti; Palmer, Dean

2009-01-01

An improved closed-loop controller has been built for a three-axis piezoelectric positioning stage. The stage can be any of a number of commercially available or custom-made units that are used for precise three-axis positioning of optics in astronomical instruments and could be used for precise positioning in diverse fields of endeavor that include adaptive optics, fabrication of semiconductors, and nanotechnology.

Ion source for high-precision mass spectrometry

DOEpatents

Todd, P.J.; McKown, H.S.; Smith, D.H.

1982-04-26

The invention is directed to a method for increasing the precision of positive-ion relative abundance measurements conducted in a sector mass spectrometer having an ion source for directing a beam of positive ions onto a collimating slit. The method comprises incorporating in the source an electrostatic lens assembly for providing a positive-ion beam of circular cross section for collimation by the slit. 2 figures, 3 tables.

Profiling Systems Using the Defining Characteristics of Systems of Systems (SoS)

DTIC Science & Technology

2010-02-01

system exhaust and emissions system gas engine heating and air conditioning system fuel system regenerative braking system safety system...overcome the limitations of these fuzzy scales, measurement scales are often divided into a relatively small number of disjoint categories so that the...precision is not justified. This lack of precision can typically be addressed by breaking the measurement scale into a set of categories , the use of

Accuracy and reliability of multi-GNSS real-time precise positioning: GPS, GLONASS, BeiDou, and Galileo

NASA Astrophysics Data System (ADS)

Li, Xingxing; Ge, Maorong; Dai, Xiaolei; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

2015-06-01

In this contribution, we present a GPS+GLONASS+BeiDou+Galileo four-system model to fully exploit the observations of all these four navigation satellite systems for real-time precise orbit determination, clock estimation and positioning. A rigorous multi-GNSS analysis is performed to achieve the best possible consistency by processing the observations from different GNSS together in one common parameter estimation procedure. Meanwhile, an efficient multi-GNSS real-time precise positioning service system is designed and demonstrated by using the multi-GNSS Experiment, BeiDou Experimental Tracking Network, and International GNSS Service networks including stations all over the world. The statistical analysis of the 6-h predicted orbits show that the radial and cross root mean square (RMS) values are smaller than 10 cm for BeiDou and Galileo, and smaller than 5 cm for both GLONASS and GPS satellites, respectively. The RMS values of the clock differences between real-time and batch-processed solutions for GPS satellites are about 0.10 ns, while the RMS values for BeiDou, Galileo and GLONASS are 0.13, 0.13 and 0.14 ns, respectively. The addition of the BeiDou, Galileo and GLONASS systems to the standard GPS-only processing, reduces the convergence time almost by 70 %, while the positioning accuracy is improved by about 25 %. Some outliers in the GPS-only solutions vanish when multi-GNSS observations are processed simultaneous. The availability and reliability of GPS precise positioning decrease dramatically as the elevation cutoff increases. However, the accuracy of multi-GNSS precise point positioning (PPP) is hardly decreased and few centimeter are still achievable in the horizontal components even with 40 elevation cutoff. At 30 and 40 elevation cutoffs, the availability rates of GPS-only solution drop significantly to only around 70 and 40 %, respectively. However, multi-GNSS PPP can provide precise position estimates continuously (availability rate is more than 99.5 %) even up to 40 elevation cutoff (e.g., in urban canyons).

A Comparative Study of Precise Point Positioning (PPP) Accuracy Using Online Services

NASA Astrophysics Data System (ADS)

Malinowski, Marcin; Kwiecień, Janusz

2016-12-01

Precise Point Positioning (PPP) is a technique used to determine the position of receiver antenna without communication with the reference station. It may be an alternative solution to differential measurements, where maintaining a connection with a single RTK station or a regional network of reference stations RTN is necessary. This situation is especially common in areas with poorly developed infrastructure of ground stations. A lot of research conducted so far on the use of the PPP technique has been concerned about the development of entire day observation sessions. However, this paper presents the results of a comparative analysis of accuracy of absolute determination of position from observations which last between 1 to 7 hours with the use of four permanent services which execute calculations with PPP technique such as: Automatic Precise Positioning Service (APPS), Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP), GNSS Analysis and Positioning Software (GAPS) and magicPPP - Precise Point Positioning Solution (magicGNSS). On the basis of acquired results of measurements, it can be concluded that at least two-hour long measurements allow acquiring an absolute position with an accuracy of 2-4 cm. An evaluation of the impact on the accuracy of simultaneous positioning of three points test network on the change of the horizontal distance and the relative height difference between measured triangle vertices was also conducted. Distances and relative height differences between points of the triangular test network measured with a laser station Leica TDRA6000 were adopted as references. The analyses of results show that at least two hours long measurement sessions can be used to determine the horizontal distance or the difference in height with an accuracy of 1-2 cm. Rapid products employed in calculations conducted with PPP technique reached the accuracy of determining coordinates on a close level as in elaborations which employ Final products.

A pioneer work on electric brain stimulation in psychotic patients. Rudolph Gottfried Arndt and his 1870s studies.

PubMed

Steinberg, Holger

2013-07-01

Today's brain stimulation methods are commonly traced back historically to surgical brain operations. With this one-sided historical approach it is easy to overlook the fact that non-surgical electrical brain-stimulating applications preceded present-day therapies. The first study on transcranial electrical brain stimulation for the treatment of severe mental diseases in a larger group of patients was carried out in the 1870s. Between 1870 and 1878 German psychiatrist Rudolph Gottfried Arndt published the results of his studies in three reports. These are contextualized with contemporary developments of the time, focusing in particular on the (neuro-) sciences. As was common practice at the time, Arndt basically reported individual cases in which electricity was applied to treat severe psychoses with depressive symptoms or even catatonia, hypochondriac delusion and melancholia. Despite their lengthiness, there is frequently a lack of precise physical data on the application of psychological-psychopathological details. Only his 1878 report includes general rules for electrical brain stimulation. Despite their methodological shortcomings and lack of precise treatment data impeding exact understanding, Arndt's studies are pioneering works in the field of electric brain stimulation with psychoses and its positive impacts. Today's transcranial direct current stimulation, and partly vagus nerve stimulation, can be compared with Arndt's methods. Although Arndt's only tangible results were indications for the application of faradic electricity (for inactivity, stupor, weakness and manic depressions) and galvanic current (for affective disorders and psychoses), a historiography of present-day brain stimulation therapies should no longer neglect studies on electrotherapy published in German and international psychiatric and neurological journals and monographs in the 1870s and 1880s. Copyright © 2013 Elsevier Inc. All rights reserved.

Development of 3-axis precise positioning seismic physical modeling system in the simulation of marine seismic exploration

NASA Astrophysics Data System (ADS)

Kim, D.; Shin, S.; Ha, J.; Lee, D.; Lim, Y.; Chung, W.

2017-12-01

Seismic physical modeling is a laboratory-scale experiment that deals with the actual and physical phenomena that may occur in the field. In seismic physical modeling, field conditions are downscaled and used. For this reason, even a small error may lead to a big error in an actual field. Accordingly, the positions of the source and the receiver must be precisely controlled in scale modeling. In this study, we have developed a seismic physical modeling system capable of precisely controlling the 3-axis position. For automatic and precise position control of an ultrasonic transducer(source and receiver) in the directions of the three axes(x, y, and z), a motor was mounted on each of the three axes. The motor can automatically and precisely control the positions with positional precision of 2''; for the x and y axes and 0.05 mm for the z axis. As it can automatically and precisely control the positions in the directions of the three axes, it has an advantage in that simulations can be carried out using the latest exploration techniques, such as OBS and Broadband Seismic. For the signal generation section, a waveform generator that can produce a maximum of two sources was used, and for the data acquisition section, which receives and stores reflected signals, an A/D converter that can receive a maximum of four signals was used. As multiple sources and receivers could be used at the same time, the system was set up in such a way that diverse exploration methods, such as single channel, multichannel, and 3-D exploration, could be realized. A computer control program based on LabVIEW was created, so that it could control the position of the transducer, determine the data acquisition parameters, and check the exploration data and progress in real time. A marine environment was simulated using a water tank 1 m wide, 1 m long, and 0.9 m high. To evaluate the performance and applicability of the seismic physical modeling system developed in this study, single channel and multichannel explorations were carried out in the marine environment and the accuracy of the modeling system was verified by comparatively analyzing the exploration data and the numerical modeling data acquired.

A Police and Insurance Joint Management System Based on High Precision BDS/GPS Positioning

PubMed Central

Zuo, Wenwei; Guo, Chi; Liu, Jingnan; Peng, Xuan; Yang, Min

2018-01-01

Car ownership in China reached 194 million vehicles at the end of 2016. The traffic congestion index (TCI) exceeds 2.0 during rush hour in some cities. Inefficient processing for minor traffic accidents is considered to be one of the leading causes for road traffic jams. Meanwhile, the process after an accident is quite troublesome. The main reason is that it is almost always impossible to get the complete chain of evidence when the accident happens. Accordingly, a police and insurance joint management system is developed which is based on high precision BeiDou Navigation Satellite System (BDS)/Global Positioning System (GPS) positioning to process traffic accidents. First of all, an intelligent vehicle rearview mirror terminal is developed. The terminal applies a commonly used consumer electronic device with single frequency navigation. Based on the high precision BDS/GPS positioning algorithm, its accuracy can reach sub-meter level in the urban areas. More specifically, a kernel driver is built to realize the high precision positioning algorithm in an Android HAL layer. Thus the third-party application developers can call the general location Application Programming Interface (API) of the original standard Global Navigation Satellite System (GNSS) to get high precision positioning results. Therefore, the terminal can provide lane level positioning service for car users. Next, a remote traffic accident processing platform is built to provide big data analysis and management. According to the big data analysis of information collected by BDS high precision intelligent sense service, vehicle behaviors can be obtained. The platform can also automatically match and screen the data that uploads after an accident to achieve accurate reproduction of the scene. Thus, it helps traffic police and insurance personnel to complete remote responsibility identification and survey for the accident. Thirdly, a rapid processing flow is established in this article to meet the requirements to quickly handle traffic accidents. The traffic police can remotely identify accident responsibility and the insurance personnel can remotely survey an accident. Moreover, the police and insurance joint management system has been carried out in Wuhan, Central China’s Hubei Province, and Wuxi, Eastern China’s Jiangsu Province. In a word, a system is developed to obtain and analyze multisource data including precise positioning and visual information, and a solution is proposed for efficient processing of traffic accidents. PMID:29320406

A Police and Insurance Joint Management System Based on High Precision BDS/GPS Positioning.

PubMed

Zuo, Wenwei; Guo, Chi; Liu, Jingnan; Peng, Xuan; Yang, Min

2018-01-10

Car ownership in China reached 194 million vehicles at the end of 2016. The traffic congestion index (TCI) exceeds 2.0 during rush hour in some cities. Inefficient processing for minor traffic accidents is considered to be one of the leading causes for road traffic jams. Meanwhile, the process after an accident is quite troublesome. The main reason is that it is almost always impossible to get the complete chain of evidence when the accident happens. Accordingly, a police and insurance joint management system is developed which is based on high precision BeiDou Navigation Satellite System (BDS)/Global Positioning System (GPS) positioning to process traffic accidents. First of all, an intelligent vehicle rearview mirror terminal is developed. The terminal applies a commonly used consumer electronic device with single frequency navigation. Based on the high precision BDS/GPS positioning algorithm, its accuracy can reach sub-meter level in the urban areas. More specifically, a kernel driver is built to realize the high precision positioning algorithm in an Android HAL layer. Thus the third-party application developers can call the general location Application Programming Interface (API) of the original standard Global Navigation Satellite System (GNSS) to get high precision positioning results. Therefore, the terminal can provide lane level positioning service for car users. Next, a remote traffic accident processing platform is built to provide big data analysis and management. According to the big data analysis of information collected by BDS high precision intelligent sense service, vehicle behaviors can be obtained. The platform can also automatically match and screen the data that uploads after an accident to achieve accurate reproduction of the scene. Thus, it helps traffic police and insurance personnel to complete remote responsibility identification and survey for the accident. Thirdly, a rapid processing flow is established in this article to meet the requirements to quickly handle traffic accidents. The traffic police can remotely identify accident responsibility and the insurance personnel can remotely survey an accident. Moreover, the police and insurance joint management system has been carried out in Wuhan, Central China's Hubei Province, and Wuxi, Eastern China's Jiangsu Province. In a word, a system is developed to obtain and analyze multisource data including precise positioning and visual information, and a solution is proposed for efficient processing of traffic accidents.

Precise Electrochemical Drilling of Repeated Deep Holes

NASA Technical Reports Server (NTRS)

Kincheloe, J. P.

1985-01-01

Tooling enables maintenance of close tolerances. Tooling includes guide that holds electrochemical drilling electrodes in proper relative alinement and guide-positioning fixture clamps directly on reference surfaces of strut. High precision achieved by positioning tooling anew on each strut before drilling: Tolerances of (0.008 mm) maintained in some details.

Pull-pull position control of dual motor wire rope transmission.

PubMed

Guo, Quan; Jiao, Zongxia; Yan, Liang; Yu, Qian; Shang, Yaoxing

2016-08-01

Wire rope transmission is very efficient because of the small total moving object mass. The wire rope could only transmit pulling force. Therefore it has to be kept in a tightened state during transmission; in high speed applications the dynamic performance depends on the rope's stiffness, which can be adjusted by the wire rope tension. To improve the system dynamic performance output, this paper proposes a novel pull-pull method based on dual motors connected by wire ropes, for precise, high speed position control applications. The method can regulate target position and wire rope tension simultaneously. Wire ropes remain in a pre-tightening state at all times, which prevents the influence of elasticity and reduces the position tracking error in the changing direction process. Simulations and experiments were conducted; the results indicate that both position precision and superior dynamic performance can be synchronously achieved. The research is relevant to space craft precision pointing instruments.

High precision position sensor based on CPA in a composite multi-layered system.

PubMed

Dey, Sanjeeb; Singh, Suneel; Rao, Desai Narayana

2018-04-16

We propose a scheme for high precision position sensing based on coherent perfect absorption (CPA) in a five-layered structure comprising three layers of metal-dielectric composites and two spacer (air) layers. Both the outermost interfaces of the five layered medium are irradiated by two identical coherent light waves at the same angle of incidence. We first investigate the occurrence of CPA in a symmetric layered structure as a function of different system parameters for oblique incidence. Thereafter, by shifting the middle layer, beginning from one end of the structure to the other, we observe the periodic occurrence of extremely narrow CPA resonances at several positions of the middle layer. Moreover this phenomenon is seen to recur even at many other wavelengths. We discuss how the position sensitivity of this phenomenon can be utilized for designing a CPA based high precision position sensing device.

Real-Time Single Frequency Precise Point Positioning Using SBAS Corrections

PubMed Central

Li, Liang; Jia, Chun; Zhao, Lin; Cheng, Jianhua; Liu, Jianxu; Ding, Jicheng

2016-01-01

Real-time single frequency precise point positioning (PPP) is a promising technique for high-precision navigation with sub-meter or even centimeter-level accuracy because of its convenience and low cost. The navigation performance of single frequency PPP heavily depends on the real-time availability and quality of correction products for satellite orbits and satellite clocks. Satellite-based augmentation system (SBAS) provides the correction products in real-time, but they are intended to be used for wide area differential positioning at 1 meter level precision. By imposing the constraints for ionosphere error, we have developed a real-time single frequency PPP method by sufficiently utilizing SBAS correction products. The proposed PPP method are tested with static and kinematic data, respectively. The static experimental results show that the position accuracy of the proposed PPP method can reach decimeter level, and achieve an improvement of at least 30% when compared with the traditional SBAS method. The positioning convergence of the proposed PPP method can be achieved in 636 epochs at most in static mode. In the kinematic experiment, the position accuracy of the proposed PPP method can be improved by at least 20 cm relative to the SBAS method. Furthermore, it has revealed that the proposed PPP method can achieve decimeter level convergence within 500 s in the kinematic mode. PMID:27517930

Combined orbits and clocks from IGS second reprocessing

NASA Astrophysics Data System (ADS)

Griffiths, Jake

2018-05-01

The Analysis Centers (ACs) of the International GNSS Service (IGS) have reprocessed a large global network of GPS tracking data from 1994.0 until 2014.0 or later. Each AC product time series was extended uniformly till early 2015 using their weekly operational IGS contributions so that the complete combined product set covers GPS weeks 730 through 1831. Three ACs also included GLONASS data from as early as 2002 but that was insufficient to permit combined GLONASS products. The reprocessed terrestrial frame combination procedures and results have been reported already, and those were incorporated into the ITRF2014 multi-technique global frame released in 2016. This paper describes the orbit and clock submissions and their multi-AC combinations and assessments. These were released to users in early 2017 in time for the adoption of IGS14 for generating the operational IGS products. While the reprocessing goal was to enable homogeneous modeling, consistent with the current operational procedures, to be applied retrospectively to the full history of observation data in order to achieve a more suitable reference for geophysical studies, that objective has only been partially achieved. Ongoing AC analysis changes and a lack of full participation limit the consistency and precision of the finished IG2 products. Quantitative internal measures indicate that the reprocessed orbits are somewhat less precise than current operational orbits or even the later orbits from the first IGS reprocessing campaign. That is even more apparent for the clocks where a lack of robust AC participation means that it was only possible to form combined 5-min clocks but not the 30-s satellite clocks published operationally. Therefore, retrospective precise point positioning solutions by users are not recommended using the orbits and clocks. Nevertheless, the orbits do support long-term stable user solutions when used with network processing with either double differencing or explicit clock estimation. Among the main benefits of the reprocessing effort is a more consistent long product set to analyze for sources of systematic error and accuracy. Work to do that is underway but the reprocessing experience already points to a number of ways future IGS performance and reprocessing campaigns can be improved.

Research gaps identified during systematic reviews of clinical trials: glass-ionomer cements.

PubMed

Mickenautsch, Steffen

2012-06-29

To report the results of an audit concerning research gaps in clinical trials that were accepted for appraisal in authored and published systematic reviews regarding the application of glass-ionomer cements (GIC) in dental practice Information concerning research gaps in trial precision was extracted, following a framework that included classification of the research gap reasons: 'imprecision of information (results)', 'biased information', 'inconsistency or unknown consistency' and 'not the right information', as well as research gap characterization using PICOS elements: population (P), intervention (I), comparison (C), outcomes (O) and setting (S). Internal trial validity assessment was based on the understanding that successful control for systematic error cannot be assured on the basis of inclusion of adequate methods alone, but also requires empirical evidence about whether such attempt was successful. A comprehensive and interconnected coverage of GIC-related clinical topics was established. The most common reasons found for gaps in trial precision were lack of sufficient trials and lack of sufficient large sample size. Only a few research gaps were ascribed to 'Lack of information' caused by focus on mainly surrogate trial outcomes. According to the chosen assessment criteria, a lack of adequate randomisation, allocation concealment and blinding/masking in trials covering all reviewed GIC topics was noted (selection- and detection/performance bias risk). Trial results appear to be less affected by loss-to-follow-up (attrition bias risk). This audit represents an adjunct of the systematic review articles it has covered. Its results do not change the systematic review's conclusions but highlight existing research gaps concerning the precision and internal validity of reviewed trials in detail. These gaps should be addressed in future GIC-related clinical research.

Regulation of nucleosome positioning by a CHD Type III chromatin remodeler and its relationship to developmental gene expression in Dictyostelium.

PubMed

Platt, James L; Kent, Nicholas A; Kimmel, Alan R; Harwood, Adrian J

2017-04-01

Nucleosome placement and repositioning can direct transcription of individual genes; however, the precise interactions of these events are complex and largely unresolved at the whole-genome level. The Chromodomain-Helicase-DNA binding (CHD) Type III proteins are a subfamily of SWI2/SNF2 proteins that control nucleosome positioning and are associated with several complex human disorders, including CHARGE syndrome and autism. Type III CHDs are required for multicellular development of animals and Dictyostelium but are absent in plants and yeast. These CHDs can mediate nucleosome translocation in vitro, but their in vivo mechanism is unknown. Here, we use genome-wide analysis of nucleosome positioning and transcription profiling to investigate the in vivo relationship between nucleosome positioning and gene expression during development of wild-type (WT) Dictyostelium and mutant cells lacking ChdC, a Type III CHD protein ortholog. We demonstrate major nucleosome positional changes associated with developmental gene regulation in WT. Loss of chdC caused an increase of intragenic nucleosome spacing and misregulation of gene expression, affecting ∼50% of the genes that are repositioned during WT development. These analyses demonstrate active nucleosome repositioning during Dictyostelium multicellular development, establish an in vivo function of CHD Type III chromatin remodeling proteins in this process, and reveal the detailed relationship between nucleosome positioning and gene regulation, as cells transition between developmental states. © 2017 Platt et al.; Published by Cold Spring Harbor Laboratory Press.

a Statistical Analysis on the System Performance of a Bluetooth Low Energy Indoor Positioning System in a 3d Environment

NASA Astrophysics Data System (ADS)

Haagmans, G. G.; Verhagen, S.; Voûte, R. L.; Verbree, E.

2017-09-01

Since GPS tends to fail for indoor positioning purposes, alternative methods like indoor positioning systems (IPS) based on Bluetooth low energy (BLE) are developing rapidly. Generally, IPS are deployed in environments covered with obstacles such as furniture, walls, people and electronics influencing the signal propagation. The major factor influencing the system performance and to acquire optimal positioning results is the geometry of the beacons. The geometry of the beacons is limited to the available infrastructure that can be deployed (number of beacons, basestations and tags), which leads to the following challenge: Given a limited number of beacons, where should they be placed in a specified indoor environment, such that the geometry contributes to optimal positioning results? This paper aims to propose a statistical model that is able to select the optimal configuration that satisfies the user requirements in terms of precision. The model requires the definition of a chosen 3D space (in our case 7 × 10 × 6 meter), number of beacons, possible user tag locations and a performance threshold (e.g. required precision). For any given set of beacon and receiver locations, the precision, internal- and external reliability can be determined on forehand. As validation, the modeled precision has been compared with observed precision results. The measurements have been performed with an IPS of BlooLoc at a chosen set of user tag locations for a given geometric configuration. Eventually, the model is able to select the optimal geometric configuration out of millions of possible configurations based on a performance threshold (e.g. required precision).

Reliable spacecraft rendezvous without velocity measurement

NASA Astrophysics Data System (ADS)

He, Shaoming; Lin, Defu

2018-03-01

This paper investigates the problem of finite-time velocity-free autonomous rendezvous for spacecraft in the presence of external disturbances during the terminal phase. First of all, to address the problem of lack of relative velocity measurement, a robust observer is proposed to estimate the unknown relative velocity information in a finite time. It is shown that the effect of external disturbances on the estimation precision can be suppressed to a relatively low level. With the reconstructed velocity information, a finite-time output feedback control law is then formulated to stabilize the rendezvous system. Theoretical analysis and rigorous proof show that the relative position and its rate can converge to a small compacted region in finite time. Numerical simulations are performed to evaluate the performance of the proposed approach in the presence of external disturbances and actuator faults.

Children facing a family member's acute illness: a review of intervention studies.

PubMed

Spath, Mary L

2007-07-01

A review of psycho-educational intervention studies to benefit children adapting to a close (parent, sibling, or grandparent) family member's serious illness was conducted. To review the literature on studies addressing this topic, critique research methods, describe clinical outcomes, and make recommendations for future research efforts. Research citations from 1990 to 2005 from Medline, CINAHL, Health Source: Nursing/Academic Edition, PsycARTICLES, and PsycINFO databases were identified. Citations were reviewed and evaluated for sample, design, theoretical framework, intervention, threats to validity, and outcomes. Reviewed studies were limited to those that included statistical analysis to evaluate interventions and outcomes. Six studies were reviewed. Positive outcomes were reported for all of the interventional strategies used in the studies. Reviewed studies generally lacked a theoretical framework and a control group, were generally composed of small convenience samples, and primarily used non-tested investigator instruments. They were diverse in terms of intervention length and intensity, and measured short-term outcomes related to participant program satisfaction, rather than participant cognitive and behavioral change. The paucity of interventional studies and lack of systematic empirical precision to evaluate intervention effectiveness necessitates future studies that are methodologically rigorous.

Precision tool holder with flexure-adjustable, three degrees of freedom for a four-axis lathe

DOEpatents

Bono, Matthew J [Pleasanton, CA; Hibbard, Robin L [Livermore, CA

2008-03-04

A precision tool holder for precisely positioning a single point cutting tool on 4-axis lathe, such that the center of the radius of the tool nose is aligned with the B-axis of the machine tool, so as to facilitate the machining of precision meso-scale components with complex three-dimensional shapes with sub-.mu.m accuracy on a four-axis lathe. The device is designed to fit on a commercial diamond turning machine and can adjust the cutting tool position in three orthogonal directions with sub-micrometer resolution. In particular, the tool holder adjusts the tool position using three flexure-based mechanisms, with two flexure mechanisms adjusting the lateral position of the tool to align the tool with the B-axis, and a third flexure mechanism adjusting the height of the tool. Preferably, the flexures are driven by manual micrometer adjusters. In this manner, this tool holder simplifies the process of setting a tool with sub-.mu.m accuracy, to substantially reduce the time required to set the tool.

Gene expression during blow fly development: improving the precision of age estimates in forensic entomology.

PubMed

Tarone, Aaron M; Foran, David R

2011-01-01

Forensic entomologists use size and developmental stage to estimate blow fly age, and from those, a postmortem interval. Since such estimates are generally accurate but often lack precision, particularly in the older developmental stages, alternative aging methods would be advantageous. Presented here is a means of incorporating developmentally regulated gene expression levels into traditional stage and size data, with a goal of more precisely estimating developmental age of immature Lucilia sericata. Generalized additive models of development showed improved statistical support compared to models that did not include gene expression data, resulting in an increase in estimate precision, especially for postfeeding third instars and pupae. The models were then used to make blind estimates of development for 86 immature L. sericata raised on rat carcasses. Overall, inclusion of gene expression data resulted in increased precision in aging blow flies. © 2010 American Academy of Forensic Sciences.

Jig For Stereoscopic Photography

NASA Technical Reports Server (NTRS)

Nielsen, David J.

1990-01-01

Separations between views adjusted precisely for best results. Simple jig adjusted to set precisely, distance between right and left positions of camera used to make stereoscopic photographs. Camera slides in slot between extreme positions, where it takes stereoscopic pictures. Distance between extreme positions set reproducibly with micrometer. In view of trend toward very-large-scale integration of electronic circuits, training method and jig used to make training photographs useful to many companies to reduce cost of training manufacturing personnel.

Precision medicine of aneurysmal subarachnoid hemorrhage, vasospasm and delayed cerebral ischemia.

PubMed

Burrell, Christian; Avalon, Nicole E; Siegel, Jason; Pizzi, Michael; Dutta, Tumpa; Charlesworth, M Cristine; Freeman, William D

2016-11-01

Precision medicine provides individualized treatment of diseases through leveraging patient-to-patient variation. Aneurysmal subarachnoid hemorrhage carries tremendous morbidity and mortality with cerebral vasospasm and delayed cerebral ischemia proving devastating and unpredictable. Lack of treatment measures for these conditions could be improved through precision medicine. Areas covered: Discussed are the pathophysiology of CV and DCI, treatment guidelines, and evidence for precision medicine used for prediction and prevention of poor outcomes following aSAH. A PubMed search was performed using keywords cerebral vasospasm or delayed cerebral ischemia and either biomarkers, precision medicine, metabolomics, proteomics, or genomics. Over 200 peer-reviewed articles were evaluated. The studies presented cover biomarkers identified as predictive markers or therapeutic targets following aSAH. Expert commentary: The biomarkers reviewed here correlate with CV, DCI, and neurologic outcomes after aSAH. Though practical use in clinical management of aSAH is not well established, using these biomarkers as predictive tools or therapeutic targets demonstrates the potential of precision medicine.

The prevalence of anti-acetylcholinesterase antibodies in autoimmune disease.

PubMed

Geen, J; Howells, R C; Ludgate, M; Hullin, D A; Hogg, S I

2004-12-01

A robust and precise enzyme linked immunosorbent assay (ELISA) with proven sensitivity and specificity has been employed to detect human antibodies (allogenic/autogenic) to human acetylcholinesterase (AChE). The sensitivity of the method has been established using mouse monoclonal antibodies (0.8 ng/ml) and uniquely, human sera positive for anti-Yt(a) allogenic antibodies, to one phenotypic form (most common) of human AChE. The latter was also used as the positive human control to ensure functionality of the assay. The ELISA method was used to establish a normal distribution curve for absorbance values employing sera from healthy blood donors Subsequently, the ELISA was employed to investigate the prevalence of anti-AChE antibodies in patients with confirmed autoimmune disease and patients with non-autoimmune thyroid disease (diseased control). The results indicate that there is not a high prevalence of anti-AChE antibodies in patients with confirmed autoimmune disease. The lack of anti-AChE autoantibodies in patients' with clinically apparent Graves' ophthalmopathy, mitigates against there being a causal role of such antibodies in Graves' associated eye disease.

Endoscopic Ultrasound (EUS) for Esophageal and Gastric Varices: How Can it Improve the Outcomes and Reduce Complications of Glue Injection

PubMed Central

Bhatia, Vikram

2012-01-01

A large part of portal venous system and the paragastric and para-esophageal collateral circulation is within the reach of endoscopic ultrasound (EUS). The EUS is more sensitive than gastroscopy for the detection of gastric varices (GV), and can accurately distinguish GV from thickened gastric folds. Gastric varices are depicted by serpiginous, anechoic, Doppler-positive mural channels, with larger collateral channels visible outside the gastric wall. The EUS has also been used to monitor the completeness of GV obturation after glue injection. There are limited data that this strategy may be clinically beneficial to prevent GV re-bleed. The EUS has been used to deliver glue injections under real-time monitoring into the vascular channels, with or without steel coils as scaffolding for the glue. The potential advantages of this technique include a straight scope position, lack of hindrance from pooled blood in gastric fundus, smaller glue volume requirements, and precise intra-vascular placement of glue with avoidance of intramural injections, and reduced embolic complications. PMID:25755407

Recent Advancements in DNA Damage-Transcription Crosstalk and High-Resolution Mapping of DNA Breaks.

PubMed

Vitelli, Valerio; Galbiati, Alessandro; Iannelli, Fabio; Pessina, Fabio; Sharma, Sheetal; d'Adda di Fagagna, Fabrizio

2017-08-31

Until recently, DNA damage arising from physiological DNA metabolism was considered a detrimental by-product for cells. However, an increasing amount of evidence has shown that DNA damage could have a positive role in transcription activation. In particular, DNA damage has been detected in transcriptional elements following different stimuli. These physiological DNA breaks are thought to be instrumental for the correct expression of genomic loci through different mechanisms. In this regard, although a plethora of methods are available to precisely map transcribed regions and transcription start sites, commonly used techniques for mapping DNA breaks lack sufficient resolution and sensitivity to draw a robust correlation between DNA damage generation and transcription. Recently, however, several methods have been developed to map DNA damage at single-nucleotide resolution, thus providing a new set of tools to correlate DNA damage and transcription. Here, we review how DNA damage can positively regulate transcription initiation, the current techniques for mapping DNA breaks at high resolution, and how these techniques can benefit future studies of DNA damage and transcription.

Precise Point Positioning technique for short and long baselines time transfer

NASA Astrophysics Data System (ADS)

Lejba, Pawel; Nawrocki, Jerzy; Lemanski, Dariusz; Foks-Ryznar, Anna; Nogas, Pawel; Dunst, Piotr

2013-04-01

In this work the clock parameters determination of several timing receivers TTS-4 (AOS), ASHTECH Z-XII3T (OP, ORB, PTB, USNO) and SEPTENTRIO POLARX4TR (ORB, since February 11, 2012) by use of the Precise Point Positioning (PPP) technique were presented. The clock parameters were determined for several time links based on the data delivered by time and frequency laboratories mentioned above. The computations cover the period from January 1 to December 31, 2012 and were performed in two modes with 7-day and one-month solution for all links. All RINEX data files which include phase and code GPS data were recorded in 30-second intervals. All calculations were performed by means of Natural Resource Canada's GPS Precise Point Positioning (GPS-PPP) software based on high-quality precise satellite coordinates and satellite clock delivered by IGS as the final products. The used independent PPP technique is a very powerful and simple method which allows for better control of antenna positions in AOS and a verification of other time transfer techniques like GPS CV, GLONASS CV and TWSTFT. The PPP technique is also a very good alternative for calibration of a glass fiber link PL-AOS realized at present by AOS. Currently PPP technique is one of the main time transfer methods used at AOS what considerably improve and strengthen the quality of the Polish time scales UTC(AOS), UTC(PL), and TA(PL). KEY-WORDS: Precise Point Positioning, time transfer, IGS products, GNSS, time scales.

On the use of particle filters for electromagnetic tracking in high dose rate brachytherapy.

PubMed

Götz, Th I; Lahmer, G; Brandt, T; Kallis, K; Strnad, V; Bert, Ch; Hensel, B; Tomé, A M; Lang, E W

2017-09-12

Modern radiotherapy of female breast cancers often employs high dose rate brachytherapy, where a radioactive source is moved inside catheters, implanted in the female breast, according to a prescribed treatment plan. Source localization relative to the patient's anatomy is determined with solenoid sensors whose spatial positions are measured with an electromagnetic tracking system. Precise sensor dwell position determination is of utmost importance to assure irradiation of the cancerous tissue according to the treatment plan. We present a hybrid data analysis system which combines multi-dimensional scaling with particle filters to precisely determine sensor dwell positions in the catheters during subsequent radiation treatment sessions. Both techniques are complemented with empirical mode decomposition for the removal of superimposed breathing artifacts. We show that the hybrid model robustly and reliably determines the spatial positions of all catheters used during the treatment and precisely determines any deviations of actual sensor dwell positions from the treatment plan. The hybrid system only relies on sensor positions measured with an EMT system and relates them to the spatial positions of the implanted catheters as initially determined with a computed x-ray tomography.

Precision medicine in pediatric oncology: Lessons learned and next steps.

PubMed

Mody, Rajen J; Prensner, John R; Everett, Jessica; Parsons, D Williams; Chinnaiyan, Arul M

2017-03-01

The maturation of genomic technologies has enabled new discoveries in disease pathogenesis as well as new approaches to patient care. In pediatric oncology, patients may now receive individualized genomic analysis to identify molecular aberrations of relevance for diagnosis and/or treatment. In this context, several recent clinical studies have begun to explore the feasibility and utility of genomics-driven precision medicine. Here, we review the major developments in this field, discuss current limitations, and explore aspects of the clinical implementation of precision medicine, which lack consensus. Lastly, we discuss ongoing scientific efforts in this arena, which may yield future clinical applications. © 2016 Wiley Periodicals, Inc.

Precision medicine in pediatric oncology: Lessons learned and next steps

PubMed Central

Mody, Rajen J.; Prensner, John R.; Everett, Jessica; Parsons, D. Williams; Chinnaiyan, Arul M.

2017-01-01

The maturation of genomic technologies has enabled new discoveries in disease pathogenesis as well as new approaches to patient care. In pediatric oncology, patients may now receive individualized genomic analysis to identify molecular aberrations of relevance for diagnosis and/or treatment. In this context, several recent clinical studies have begun to explore the feasibility and utility of genomics-driven precision medicine. Here, we review the major developments in this field, discuss current limitations, and explore aspects of the clinical implementation of precision medicine, which lack consensus. Lastly, we discuss ongoing scientific efforts in this arena, which may yield future clinical applications. PMID:27748023

Use of Terrestrial Laser Scanning Technology for Long Term High Precision Deformation Monitoring

PubMed Central

Vezočnik, Rok; Ambrožič, Tomaž; Sterle, Oskar; Bilban, Gregor; Pfeifer, Norbert; Stopar, Bojan

2009-01-01

The paper presents a new methodology for high precision monitoring of deformations with a long term perspective using terrestrial laser scanning technology. In order to solve the problem of a stable reference system and to assure the high quality of possible position changes of point clouds, scanning is integrated with two complementary surveying techniques, i.e., high quality static GNSS positioning and precise tacheometry. The case study object where the proposed methodology was tested is a high pressure underground pipeline situated in an area which is geologically unstable. PMID:22303152

Demonstrating Hemostasis with a Student-Designed Prothrombin Time Test

ERIC Educational Resources Information Center

Fardy, Richard Wiley

1978-01-01

Describes a blood coagulation test developed by two high school biology students. Although the test lacks some precision, results indicate that the technique is comparable to standard methods used in laboratories. (MA)

Distribution and mitigation of higher-order ionospheric effects on precise GNSS processing

NASA Astrophysics Data System (ADS)

Hernández-Pajares, Manuel; Aragón-Ángel, Àngela; Defraigne, Pascale; Bergeot, Nicolas; Prieto-Cerdeira, Roberto; García-Rigo, Alberto

2014-04-01

Higher-order ionospheric effects (I2+) are one of the main limiting factors in very precise Global Navigation Satellite Systems (GNSS) processing, for applications where millimeter accuracy is demanded. This paper summarizes a comprehensive study of the I2+ effects in range and in GNSS precise products such as receiver position and clock, tropospheric delay, geocenter offset, and GNSS satellite position and clock. All the relevant higher-order contributions are considered: second and third orders, geometric bending, and slant total electron content (dSTEC) bending (i.e., the difference between the STEC for straight and bent paths). Using a realistic simulation with representative solar maximum conditions on GPS signals, both the effects and mitigation errors are analyzed. The usage of the combination of multifrequency L band observations has to be rejected due to its increased noise level. The results of the study show that the main two effects in range are the second-order ionospheric and dSTEC terms, with peak values up to 2 cm. Their combined impacts on the precise GNSS satellite products affects the satellite Z coordinates (up to +1 cm) and satellite clocks (more than ±20 ps). Other precise products are affected at the millimeter level. After correction the impact on all the precise GNSS products is reduced below 5 mm. We finally show that the I2+ impact on a Precise Point Positioning (PPP) user is lower than the current uncertainties of the PPP solutions, after applying consistently the precise products (satellite orbits and clocks) obtained under I2+ correction.

Exploring the Relationship of Task Performance and Physical and Cognitive Fatigue During a Daylong Light Precision Task.

PubMed

Yung, Marcus; Manji, Rahim; Wells, Richard P

2017-11-01

Our aim was to explore the relationship between fatigue and operation system performance during a simulated light precision task over an 8-hr period using a battery of physical (central and peripheral) and cognitive measures. Fatigue may play an important role in the relationship between poor ergonomics and deficits in quality and productivity. However, well-controlled laboratory studies in this area have several limitations, including the lack of work relevance of fatigue exposures and lack of both physical and cognitive measures. There remains a need to understand the relationship between physical and cognitive fatigue and task performance at exposure levels relevant to realistic production or light precision work. Errors and fatigue measures were tracked over the course of a micropipetting task. Fatigue responses from 10 measures and errors in pipetting technique, precision, and targeting were submitted to principal component analysis to descriptively analyze features and patterns. Fatigue responses and error rates contributed to three principal components (PCs), accounting for 50.9% of total variance. Fatigue responses grouped within the three PCs reflected central and peripheral upper extremity fatigue, postural sway, and changes in oculomotor behavior. In an 8-hr light precision task, error rates shared similar patterns to both physical and cognitive fatigue responses, and/or increases in arousal level. The findings provide insight toward the relationship between fatigue and operation system performance (e.g., errors). This study contributes to a body of literature documenting task errors and fatigue, reflecting physical (both central and peripheral) and cognitive processes.

Precision disablement aiming system

DOEpatents

Monda, Mark J.; Hobart, Clinton G.; Gladwell, Thomas Scott

2016-02-16

A disrupter to a target may be precisely aimed by positioning a radiation source to direct radiation towards the target, and a detector is positioned to detect radiation that passes through the target. An aiming device is positioned between the radiation source and the target, wherein a mechanical feature of the aiming device is superimposed on the target in a captured radiographic image. The location of the aiming device in the radiographic image is used to aim a disrupter towards the target.

Precision Positioning and Inertial Guidance Sensors. Technology and Operational Aspects

DTIC Science & Technology

1981-03-01

Ueberlingen, GE EVALUATION D’UN SYSTEME EUROPEEN DE NAVIGATION HYBRIDE A - - GYROLASER POUR HELICOPTERE: "SEXTAN" by D Regnault, Centre d’Essais en Vol de...NAVIGATION SYSTEM AND STANDARD STATE ELEMENT DEVIATIONMEASUREMENT SOURCES( Dead-reckoning with position fxP fy 5000 En ]TAS, heading and wind scale...Reproduction Ltd ilarford House. 7-9 Charlotte St. London. WIP JIHD [i Ii THEME A new class of precision positioning systems , including GPS (Global

High-precision positioning system of four-quadrant detector based on the database query

NASA Astrophysics Data System (ADS)

Zhang, Xin; Deng, Xiao-guo; Su, Xiu-qin; Zheng, Xiao-qiang

2015-02-01

The fine pointing mechanism of the Acquisition, Pointing and Tracking (APT) system in free space laser communication usually use four-quadrant detector (QD) to point and track the laser beam accurately. The positioning precision of QD is one of the key factors of the pointing accuracy to APT system. A positioning system is designed based on FPGA and DSP in this paper, which can realize the sampling of AD, the positioning algorithm and the control of the fast swing mirror. We analyze the positioning error of facular center calculated by universal algorithm when the facular energy obeys Gauss distribution from the working principle of QD. A database is built by calculation and simulation with MatLab software, in which the facular center calculated by universal algorithm is corresponded with the facular center of Gaussian beam, and the database is stored in two pieces of E2PROM as the external memory of DSP. The facular center of Gaussian beam is inquiry in the database on the basis of the facular center calculated by universal algorithm in DSP. The experiment results show that the positioning accuracy of the high-precision positioning system is much better than the positioning accuracy calculated by universal algorithm.

Precise Point Positioning Based on BDS and GPS Observations

NASA Astrophysics Data System (ADS)

Gao, ZhouZheng; Zhang, Hongping; Shen, Wenbin

2014-05-01

BeiDou Navigation Satellite System (BDS) has obtained the ability applying initial navigation and precise point services for the Asian-Pacific regions at the end of 2012 with the constellation of 5 Geostationary Earth Orbit (GEO), 5 Inclined Geosynchronous Orbit (IGSO) and 4 Medium Earth Orbit (MEO). Till 2020, it will consist with 5 GEO, 3 IGSO and 27 MEO, and apply global navigation service similar to GPS and GLONASS. As we known, GPS precise point positioning (PPP) is a powerful tool for crustal deformation monitoring, GPS meteorology, orbit determination of low earth orbit satellites, high accuracy kinematic positioning et al. However, it accuracy and convergence time are influenced by the quality of pseudo-range observations and the observing geometry between user and Global navigation satellites system (GNSS) satellites. Usually, it takes more than 30 minutes even hours to obtain centimeter level position accuracy for PPP while using GPS dual-frequency observations only. In recent years, many researches have been done to solve this problem. One of the approaches is smooth pseudo-range by carrier-phase observations to improve pseudo-range accuracy. By which can improve PPP initial position accuracy and shorten PPP convergence time. Another sachems is to change position dilution of precision (PDOP) with multi-GNSS observations. Now, BDS has the ability to service whole Asian-Pacific regions, which make it possible to use GPS and BDS for precise positioning. In addition, according to researches on GNSS PDOP distribution, BDS can improve PDOP obviously. Therefore, it necessary to do some researches on PPP performance using both GPS observations and BDS observations, especially in Asian-Pacific regions currently. In this paper, we focus on the influences of BDS to GPS PPP mainly in three terms including BDS PPP accuracy, PDOP improvement and convergence time of PPP based on GPS and BDS observations. Here, the GPS and BDS two-constellation data are collected from BeiDou experimental tracking stations (BETS) built by Wuhan University. And BDS precise orbit and precise clock products are applied by GNSS center, Wuhan University. After an introduction about GPS+BDS PPP mathematical and the error correction modes, we analyze the influence of BDS to GPS PPP carefully with calculating results. The statistics results show that BDS PPP can reach centimeter level and BDS can improve PDOP obviously. Moreover, the convergence time and position stability of GPS+BDS PPP is better than that of GPS PPP.

An Investigation on the Contribution of GLONASS to the Precise Point Positioning for Short Time Observations

NASA Astrophysics Data System (ADS)

Ulug, R.; Ozludemir, M. T.

2016-12-01

After 2011, through the modernization process of GLONASS, the number of satellites increased rapidly. This progress has made the GLONASS the only fully operational system alternative to GPS in point positioning. So far, many researches have been conducted to investigate the contribution of GLONASS to point positioning considering different methods such as Real Time Kinematic (RTK) and Precise Point Positioning (PPP). The latter one, PPP, is a method that performs precise position determination using a single GNSS receiver. PPP method has become very attractive since the early 2000s and it provided great advantages for engineering and scientific applications. However, PPP method needs at least 2 hours observation time and the required observation length may be longer depending on several factors, such as the number of satellites, satellite configuration etc. The more satellites, the less observation time. Nevertheless the impact of the number of satellites included must be known very well. In this study, to determine the contribution of GLONASS on PPP, GLONASS satellite observations were added one by one from 1 to 5 satellite in 2, 4 and 6 hours of observations. For this purpose, the data collected at the IGS site ISTA was used. Data processing has been done for Day of Year (DOY) 197 in 2016. 24 hours GPS observations have been processed by Bernese 5.2 PPP module and the output was selected as the reference while 2, 4 and 6 hours GPS and GPS/GLONASS observations have been processed by magic GNSS PPP module. The results clearly showed that GPS/GLONASS observations improved positional accuracy, precision, dilution of precision and convergence to the reference coordinates. In this context, coordinate differences between 24 hours GPS observations and 6 hours GPS/GLONASS observations have been obtained as less than 2 cm.

Setting objective thresholds for rare event detection in flow cytometry

PubMed Central

Richards, Adam J.; Staats, Janet; Enzor, Jennifer; McKinnon, Katherine; Frelinger, Jacob; Denny, Thomas N.; Weinhold, Kent J.; Chan, Cliburn

2014-01-01

The accurate identification of rare antigen-specific cytokine positive cells from peripheral blood mononuclear cells (PBMC) after antigenic stimulation in an intracellular staining (ICS) flow cytometry assay is challenging, as cytokine positive events may be fairly diffusely distributed and lack an obvious separation from the negative population. Traditionally, the approach by flow operators has been to manually set a positivity threshold to partition events into cytokine-positive and cytokine-negative. This approach suffers from subjectivity and inconsistency across different flow operators. The use of statistical clustering methods does not remove the need to find an objective threshold between between positive and negative events since consistent identification of rare event subsets is highly challenging for automated algorithms, especially when there is distributional overlap between the positive and negative events (“smear”). We present a new approach, based on the Fβ measure, that is similar to manual thresholding in providing a hard cutoff, but has the advantage of being determined objectively. The performance of this algorithm is compared with results obtained by expert visual gating. Several ICS data sets from the External Quality Assurance Program Oversight Laboratory (EQAPOL) proficiency program were used to make the comparisons. We first show that visually determined thresholds are difficult to reproduce and pose a problem when comparing results across operators or laboratories, as well as problems that occur with the use of commonly employed clustering algorithms. In contrast, a single parameterization for the Fβ method performs consistently across different centers, samples, and instruments because it optimizes the precision/recall tradeoff by using both negative and positive controls. PMID:24727143

Precise positioning method for multi-process connecting based on binocular vision

NASA Astrophysics Data System (ADS)

Liu, Wei; Ding, Lichao; Zhao, Kai; Li, Xiao; Wang, Ling; Jia, Zhenyuan

2016-01-01

With the rapid development of aviation and aerospace, the demand for metal coating parts such as antenna reflector, eddy-current sensor and signal transmitter, etc. is more and more urgent. Such parts with varied feature dimensions, complex three-dimensional structures, and high geometric accuracy are generally fabricated by the combination of different manufacturing technology. However, it is difficult to ensure the machining precision because of the connection error between different processing methods. Therefore, a precise positioning method is proposed based on binocular micro stereo vision in this paper. Firstly, a novel and efficient camera calibration method for stereoscopic microscope is presented to solve the problems of narrow view field, small depth of focus and too many nonlinear distortions. Secondly, the extraction algorithms for law curve and free curve are given, and the spatial position relationship between the micro vision system and the machining system is determined accurately. Thirdly, a precise positioning system based on micro stereovision is set up and then embedded in a CNC machining experiment platform. Finally, the verification experiment of the positioning accuracy is conducted and the experimental results indicated that the average errors of the proposed method in the X and Y directions are 2.250 μm and 1.777 μm, respectively.

Development of an ultrasonic linear motor with ultra-positioning capability and four driving feet.

PubMed

Zhu, Cong; Chu, Xiangcheng; Yuan, Songmei; Zhong, Zuojin; Zhao, Yanqiang; Gao, Shuning

2016-12-01

This paper presents a novel linear piezoelectric motor which is suitable for rapid ultra-precision positioning. The finite element analysis (FEA) was applied for optimal design and further analysis, then experiments were conducted to investigate its performance. By changing the input signal, the proposed motor was found capable of working in the fast driving mode as well as in the precision positioning mode. When working in the fast driving mode, the motor acts as an ultrasonic motor with maximum no-load speed up to 181.2mm/s and maximum thrust of 1.7N at 200Vp-p. Also, when working in precision positioning mode, the motor can be regarded as a flexible hinge piezoelectric actuator with arbitrary motion in the range of 8μm. The measurable minimum output displacement was found to be 0.08μm, but theoretically, can be even smaller. More importantly, the motor can be quickly and accurately positioned in a large stroke. Copyright © 2016 Elsevier B.V. All rights reserved.

Reliability, precision, and gender differences in knee internal/external rotation proprioception measurements.

PubMed

Nagai, Takashi; Sell, Timothy C; Abt, John P; Lephart, Scott M

2012-11-01

To develop and assess the reliability and precision of knee internal/external rotation (IR/ER) threshold to detect passive motion (TTDPM) and determine if gender differences exist. Test-retest for the reliability/precision and cross-sectional for gender comparisons. University neuromuscular and human performance research laboratory. Ten subjects for the reliability and precision aim. Twenty subjects (10 males and 10 females) for gender comparisons. All TTDPM tests were performed using a multi-mode dynamometer. Subjects performed TTDPM at two knee positions (near IR or ER end-range). Intraclass correlation coefficient (ICC (3,k)) and standard error of measurement (SEM) were used to evaluate the reliability and precision. Independent t-tests were used to compare genders. TTDPM toward IR and ER at two knee positions. Intrasession and intersession reliability and precision were good (ICC=0.68-0.86; SEM=0.22°-0.37°). Females had significantly diminished TTDPM toward IR at IR-test position (males: 0.77°±0.14°, females: 1.18°±0.46°, p=0.021) and TTDPM toward IR at the ER-test position (males: 0.87°±0.13°, females: 1.36°±0.58°, p=0.026). No other significant gender differences were found (p>0.05). The current IR/ER TTDPM methods are reliable and accurate for the test-retest or cross-section research design. Gender differences were found toward IR where the ACL acts as the secondary restraint. Copyright © 2011 Elsevier Ltd. All rights reserved.

Indexing system for optical beam steering

NASA Technical Reports Server (NTRS)

Sullivan, Mark T.; Cannon, David M.; Debra, Daniel B.; Young, Jeffrey A.; Mansfield, Joseph A.; Carmichael, Roger E.; Lissol, Peter S.; Pryor, G. M.; Miklosy, Les G.; Lee, Jeffrey H.

1990-01-01

This paper describes the design and testing of an indexing system for optical-beam steering. The cryogenic beam-steering mechanism is a 360-degree rotation device capable of discrete, high-precision alignment positions. It uses low-precision components for its rough alignment and kinematic design to meet its stringent repeatability and stability requirements (of about 5 arcsec). The principal advantages of this design include a decoupling of the low-precision, large angular motion from the high-precision alignment, and a power-off alignment position that potentially extends the life or hold time of cryogenic systems. An alternate design, which takes advantage of these attributes while reducing overall motion, is also presented. Preliminary test results show the kinematic mount capable of sub-arc second repeatability.

IEEE 802.15.4 ZigBee-Based Time-of-Arrival Estimation for Wireless Sensor Networks.

PubMed

Cheon, Jeonghyeon; Hwang, Hyunsu; Kim, Dongsun; Jung, Yunho

2016-02-05

Precise time-of-arrival (TOA) estimation is one of the most important techniques in RF-based positioning systems that use wireless sensor networks (WSNs). Because the accuracy of TOA estimation is proportional to the RF signal bandwidth, using broad bandwidth is the most fundamental approach for achieving higher accuracy. Hence, ultra-wide-band (UWB) systems with a bandwidth of 500 MHz are commonly used. However, wireless systems with broad bandwidth suffer from the disadvantages of high complexity and high power consumption. Therefore, it is difficult to employ such systems in various WSN applications. In this paper, we present a precise time-of-arrival (TOA) estimation algorithm using an IEEE 802.15.4 ZigBee system with a narrow bandwidth of 2 MHz. In order to overcome the lack of bandwidth, the proposed algorithm estimates the fractional TOA within the sampling interval. Simulation results show that the proposed TOA estimation algorithm provides an accuracy of 0.5 m at a signal-to-noise ratio (SNR) of 8 dB and achieves an SNR gain of 5 dB as compared with the existing algorithm. In addition, experimental results indicate that the proposed algorithm provides accurate TOA estimation in a real indoor environment.

Active-passive hybrid piezoelectric actuators for high-precision hard disk drive servo systems

NASA Astrophysics Data System (ADS)

Chan, Kwong Wah; Liao, Wei-Hsin

2006-03-01

Positioning precision is crucial to today's increasingly high-speed, high-capacity, high data density, and miniaturized hard disk drives (HDDs). The demand for higher bandwidth servo systems that can quickly and precisely position the read/write head on a high track density becomes more pressing. Recently, the idea of applying dual-stage actuators to track servo systems has been studied. The push-pull piezoelectric actuated devices have been developed as micro actuators for fine and fast positioning, while the voice coil motor functions as a large but coarse seeking. However, the current dual-stage actuator design uses piezoelectric patches only without passive damping. In this paper, we propose a dual-stage servo system using enhanced active-passive hybrid piezoelectric actuators. The proposed actuators will improve the existing dual-stage actuators for higher precision and shock resistance, due to the incorporation of passive damping in the design. We aim to develop this hybrid servo system not only to increase speed of track seeking but also to improve precision of track following servos in HDDs. New piezoelectrically actuated suspensions with passive damping have been designed and fabricated. In order to evaluate positioning and track following performances for the dual-stage track servo systems, experimental efforts are carried out to implement the synthesized active-passive suspension structure with enhanced piezoelectric actuators using a composite nonlinear feedback controller.

Canceling the Gravity Gradient Phase Shift in Atom Interferometry.

PubMed

D'Amico, G; Rosi, G; Zhan, S; Cacciapuoti, L; Fattori, M; Tino, G M

2017-12-22

Gravity gradients represent a major obstacle in high-precision measurements by atom interferometry. Controlling their effects to the required stability and accuracy imposes very stringent requirements on the relative positioning of freely falling atomic clouds, as in the case of precise tests of Einstein's equivalence principle. We demonstrate a new method to exactly compensate the effects introduced by gravity gradients in a Raman-pulse atom interferometer. By shifting the frequency of the Raman lasers during the central π pulse, it is possible to cancel the initial position- and velocity-dependent phase shift produced by gravity gradients. We apply this technique to simultaneous interferometers positioned along the vertical direction and demonstrate a new method for measuring local gravity gradients that does not require precise knowledge of the relative position between the atomic clouds. Based on this method, we also propose an improved scheme to determine the Newtonian gravitational constant G towards the 10 ppm relative uncertainty.

A method of undifferenced ambiguity resolution for GPS+GLONASS precise point positioning

PubMed Central

Yi, Wenting; Song, Weiwei; Lou, Yidong; Shi, Chuang; Yao, Yibin

2016-01-01

Integer ambiguity resolution is critical for achieving positions of high precision and for shortening the convergence time of precise point positioning (PPP). However, GLONASS adopts the signal processing technology of frequency division multiple access and results in inter-frequency code biases (IFCBs), which are currently difficult to correct. This bias makes the methods proposed for GPS ambiguity fixing unsuitable for GLONASS. To realize undifferenced GLONASS ambiguity fixing, we propose an undifferenced ambiguity resolution method for GPS+GLONASS PPP, which considers the IFCBs estimation. The experimental result demonstrates that the success rate of GLONASS ambiguity fixing can reach 75% through the proposed method. Compared with the ambiguity float solutions, the positioning accuracies of ambiguity-fixed solutions of GLONASS-only PPP are increased by 12.2%, 20.9%, and 10.3%, and that of the GPS+GLONASS PPP by 13.0%, 35.2%, and 14.1% in the North, East and Up directions, respectively. PMID:27222361

A method of undifferenced ambiguity resolution for GPS+GLONASS precise point positioning.

PubMed

Yi, Wenting; Song, Weiwei; Lou, Yidong; Shi, Chuang; Yao, Yibin

2016-05-25

Integer ambiguity resolution is critical for achieving positions of high precision and for shortening the convergence time of precise point positioning (PPP). However, GLONASS adopts the signal processing technology of frequency division multiple access and results in inter-frequency code biases (IFCBs), which are currently difficult to correct. This bias makes the methods proposed for GPS ambiguity fixing unsuitable for GLONASS. To realize undifferenced GLONASS ambiguity fixing, we propose an undifferenced ambiguity resolution method for GPS+GLONASS PPP, which considers the IFCBs estimation. The experimental result demonstrates that the success rate of GLONASS ambiguity fixing can reach 75% through the proposed method. Compared with the ambiguity float solutions, the positioning accuracies of ambiguity-fixed solutions of GLONASS-only PPP are increased by 12.2%, 20.9%, and 10.3%, and that of the GPS+GLONASS PPP by 13.0%, 35.2%, and 14.1% in the North, East and Up directions, respectively.

Canceling the Gravity Gradient Phase Shift in Atom Interferometry

NASA Astrophysics Data System (ADS)

D'Amico, G.; Rosi, G.; Zhan, S.; Cacciapuoti, L.; Fattori, M.; Tino, G. M.

2017-12-01

Gravity gradients represent a major obstacle in high-precision measurements by atom interferometry. Controlling their effects to the required stability and accuracy imposes very stringent requirements on the relative positioning of freely falling atomic clouds, as in the case of precise tests of Einstein's equivalence principle. We demonstrate a new method to exactly compensate the effects introduced by gravity gradients in a Raman-pulse atom interferometer. By shifting the frequency of the Raman lasers during the central π pulse, it is possible to cancel the initial position- and velocity-dependent phase shift produced by gravity gradients. We apply this technique to simultaneous interferometers positioned along the vertical direction and demonstrate a new method for measuring local gravity gradients that does not require precise knowledge of the relative position between the atomic clouds. Based on this method, we also propose an improved scheme to determine the Newtonian gravitational constant G towards the 10 ppm relative uncertainty.

Semi-Major Axis Knowledge and GPS Orbit Determination

NASA Technical Reports Server (NTRS)

Carpenter, J. Russell; Schiesser, Emil R.; Bauer, F. (Technical Monitor)

2000-01-01

In recent years spacecraft designers have increasingly sought to use onboard Global Positioning System receivers for orbit determination. The superb positioning accuracy of GPS has tended to focus more attention on the system's capability to determine the spacecraft's location at a particular epoch than on accurate orbit determination, per se. The determination of orbit plane orientation and orbit shape to acceptable levels is less challenging than the determination of orbital period or semi-major axis. It is necessary to address semi-major axis mission requirements and the GPS receiver capability for orbital maneuver targeting and other operations that require trajectory prediction. Failure to determine semi-major axis accurately can result in a solution that may not be usable for targeting the execution of orbit adjustment and rendezvous maneuvers. Simple formulas, charts, and rules of thumb relating position, velocity, and semi-major axis are useful in design and analysis of GPS receivers for near circular orbit operations, including rendezvous and formation flying missions. Space Shuttle flights of a number of different GPS receivers, including a mix of unfiltered and filtered solution data and Standard and Precise Positioning Service modes, have been accomplished. These results indicate that semi-major axis is often not determined very accurately, due to a poor velocity solution and a lack of proper filtering to provide good radial and speed error correlation.

Semi-Major Axis Knowledge and GPS Orbit Determination

NASA Technical Reports Server (NTRS)

Carpenter, J. Russell; Schiesser, Emil R.; Bauer, F. (Technical Monitor)

2000-01-01

In recent years spacecraft designers have increasingly sought to use onboard Global Positioning System receivers for orbit determination. The superb positioning accuracy of GPS has tended to focus more attention on the system's capability to determine the spacecraft's location at a particular epoch than on accurate orbit determination, per se. The determination of orbit plane orientation and orbit shape to acceptable levels is less challenging than the determination of orbital period or semi-major axis. It is necessary to address semi-major axis mission requirements and the GPS receiver capability for orbital maneuver targeting and other operations that require trajectory prediction. Failure to determine semi-major axis accurately can result in a solution that may not be usable for targeting the execution of orbit adjustment and rendezvous maneuvers. Simple formulas, charts, and rules of thumb relating position, velocity, and semi-major axis are useful in design and analysis of GPS receivers for near circular orbit operations, including rendezvous and formation flying missions. Space Shuttle flights of a number of different GPS receivers, including a mix of unfiltered and filtered solution data and Standard and Precise Positioning, Service modes, have been accomplished. These results indicate that semi-major axis is often not determined very accurately, due to a poor velocity solution and a lack of proper filtering to provide good radial and speed error correlation.

Three-dimensional high-precision indoor positioning strategy using Tabu search based on visible light communication

NASA Astrophysics Data System (ADS)

Peng, Qi; Guan, Weipeng; Wu, Yuxiang; Cai, Ye; Xie, Canyu; Wang, Pengfei

2018-01-01

This paper proposes a three-dimensional (3-D) high-precision indoor positioning strategy using Tabu search based on visible light communication. Tabu search is a powerful global optimization algorithm, and the 3-D indoor positioning can be transformed into an optimal solution problem. Therefore, in the 3-D indoor positioning, the optimal receiver coordinate can be obtained by the Tabu search algorithm. For all we know, this is the first time the Tabu search algorithm is applied to visible light positioning. Each light-emitting diode (LED) in the system broadcasts a unique identity (ID) and transmits the ID information. When the receiver detects optical signals with ID information from different LEDs, using the global optimization of the Tabu search algorithm, the 3-D high-precision indoor positioning can be realized when the fitness value meets certain conditions. Simulation results show that the average positioning error is 0.79 cm, and the maximum error is 5.88 cm. The extended experiment of trajectory tracking also shows that 95.05% positioning errors are below 1.428 cm. It can be concluded from the data that the 3-D indoor positioning based on the Tabu search algorithm achieves the requirements of centimeter level indoor positioning. The algorithm used in indoor positioning is very effective and practical and is superior to other existing methods for visible light indoor positioning.

A Simple Method to Improve Autonomous GPS Positioning for Tractors

PubMed Central

Gomez-Gil, Jaime; Alonso-Garcia, Sergio; Gómez-Gil, Francisco Javier; Stombaugh, Tim

2011-01-01

Error is always present in the GPS guidance of a tractor along a desired trajectory. One way to reduce GPS guidance error is by improving the tractor positioning. The most commonly used ways to do this are either by employing more precise GPS receivers and differential corrections or by employing GPS together with some other local positioning systems such as electronic compasses or Inertial Navigation Systems (INS). However, both are complex and expensive solutions. In contrast, this article presents a simple and low cost method to improve tractor positioning when only a GPS receiver is used as the positioning sensor. The method is based on placing the GPS receiver ahead of the tractor, and on applying kinematic laws of tractor movement, or a geometric approximation, to obtain the midpoint position and orientation of the tractor rear axle more precisely. This precision improvement is produced by the fusion of the GPS data with tractor kinematic control laws. Our results reveal that the proposed method effectively reduces the guidance GPS error along a straight trajectory. PMID:22163917

What's in a Name? Moral Education and Terminological Precision.

ERIC Educational Resources Information Center

Cheek, Dallas Henderson; Cheek, Carole Maxwell

1993-01-01

Although many blame societal relativism for lack of moral vision, the term "moral education" is not being used with clarity and specificity. Confusing it with values/ethics/character training makes curricular application difficult. (SK)

Error analysis of high-rate GNSS precise point positioning for seismic wave measurement

NASA Astrophysics Data System (ADS)

Shu, Yuanming; Shi, Yun; Xu, Peiliang; Niu, Xiaoji; Liu, Jingnan

2017-06-01

High-rate GNSS precise point positioning (PPP) has been playing a more and more important role in providing precise positioning information in fast time-varying environments. Although kinematic PPP is commonly known to have a precision of a few centimeters, the precision of high-rate PPP within a short period of time has been reported recently with experiments to reach a few millimeters in the horizontal components and sub-centimeters in the vertical component to measure seismic motion, which is several times better than the conventional kinematic PPP practice. To fully understand the mechanism of mystified excellent performance of high-rate PPP within a short period of time, we have carried out a theoretical error analysis of PPP and conducted the corresponding simulations within a short period of time. The theoretical analysis has clearly indicated that the high-rate PPP errors consist of two types: the residual systematic errors at the starting epoch, which affect high-rate PPP through the change of satellite geometry, and the time-varying systematic errors between the starting epoch and the current epoch. Both the theoretical error analysis and simulated results are fully consistent with and thus have unambiguously confirmed the reported high precision of high-rate PPP, which has been further affirmed here by the real data experiments, indicating that high-rate PPP can indeed achieve the millimeter level of precision in the horizontal components and the sub-centimeter level of precision in the vertical component to measure motion within a short period of time. The simulation results have clearly shown that the random noise of carrier phases and higher order ionospheric errors are two major factors to affect the precision of high-rate PPP within a short period of time. The experiments with real data have also indicated that the precision of PPP solutions can degrade to the cm level in both the horizontal and vertical components, if the geometry of satellites is rather poor with a large DOP value.

Seismic displacements monitoring for 2015 Mw 7.8 Nepal earthquake with GNSS data

NASA Astrophysics Data System (ADS)

Geng, T.; Su, X.; Xie, X.

2017-12-01

The high-rate Global Positioning Satellite System (GNSS) has been recognized as one of the powerful tools for monitoring ground motions generated by seismic events. The high-rate GPS and BDS data collected during the 2015 Mw 7.8 Nepal earthquake have been analyzed using two methods, that are the variometric approach and Precise point positioning (PPP). The variometric approach is based on time differenced technique using only GNSS broadcast products to estimate velocity time series from tracking observations in real time, followed by an integration procedure on the velocities to derive the seismic event induced displacements. PPP is a positioning method to calculate precise positions at centimeter- or even millimeter-level accuracy with a single GNSS receiver using precise satellite orbit and clock products. The displacement motions with accuracy of 2 cm at far-field stations and 5 cm at near-field stations with great ground motions and static offsets up to 1-2 m could be achieved. The multi-GNSS, GPS + BDS, could provide higher accuracy displacements with the increasing of satellite numbers and the improvement of the Position Dilution of Precision (PDOP) values. Considering the time consumption of clock estimates and the precision of PPP solutions, 5 s GNSS satellite clock interval is suggested. In addition, the GNSS-derived displacements are in good agreement with those from strong motion data. These studies demonstrate the feasibility of real-time capturing seismic waves with multi-GNSS observations, which is of great promise for the purpose of earthquake early warning and rapid hazard assessment.

Precisely detecting atomic position of atomic intensity images.

PubMed

Wang, Zhijun; Guo, Yaolin; Tang, Sai; Li, Junjie; Wang, Jincheng; Zhou, Yaohe

2015-03-01

We proposed a quantitative method to detect atomic position in atomic intensity images from experiments such as high-resolution transmission electron microscopy, atomic force microscopy, and simulation such as phase field crystal modeling. The evaluation of detection accuracy proves the excellent performance of the method. This method provides a chance to precisely determine atomic interactions based on the detected atomic positions from the atomic intensity image, and hence to investigate the related physical, chemical and electrical properties. Copyright © 2014 Elsevier B.V. All rights reserved.

Lens positioner with five degrees of freedom

DOEpatents

Kobierecki, Marian W.; Rienecker, Jr., Frederick

1978-01-01

A device for positioning lenses precisely with five degrees of freedom (three translations and two angular rotations). The unique features of the device are its compact design, large clear aperture, and high degree of positioning accuracy combined with five degrees of freedom in axis motion. Thus, the device provides precision and flexibility in positioning of optical components. BACKGROUND OF THE INVENTION The invention described herein was made in the course of, or under, Contract No. AT(29-1)-1183, with the United States Energy Research and Development Administration.

Measuring Turbulence from Moored Acoustic Doppler Velocimeters. A Manual to Quantifying Inflow at Tidal Energy Sites

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

Kilcher, Levi; Thomson, Jim; Talbert, Joe

This work details a methodology for measuring hub height inflow turbulence using moored acoustic Doppler velocimiters (ADVs). This approach is motivated by the shortcomings of alternatives. For example, remote velocity measurements (i.e., from acoustic Doppler profilers) lack sufficient precision for device simulation, and rigid tower-mounted measurements are very expensive and technically challenging in the tidal environment. Moorings offer a low-cost, site-adaptable and robust deployment platform, and ADVs provide the necessary precision to accurately quantify turbulence.

Introduction to Precision Guided Munitions, A Handbook Providing Tutorial Information and Data on Precision Guided Munitions (PGM). Volume 1. Tutorial. Revision

DTIC Science & Technology

1983-05-01

serve as inter- faces to provide a compatible hook-up. Recent advances in microprocessors are leaoing to the development of new techniques known as...killed. This sort of threat is new to warfare. Because of the lack of experience against such a threat, effective tactics have not been developed ...Recent developments have been on satellite-to-earth communications links, antijam capabilities, adaptive array antennas, and new equipment to exploit the

Precision or Personalized Medicine for Cancer Chemotherapy: Is there a Role for Herbal Medicine.

PubMed

Wang, Zhijun; Liu, Xuefeng; Ho, Rebecca Lucinda Ka Yan; Lam, Christopher Wai Kei; Chow, Moses Sing Sum

2016-07-07

Although over 100 chemotherapeutic agents are currently available for the treatment of cancer patients, the overall long term clinical benefit is disappointing due to the lack of effectiveness or severe side effects from these agents. In order to improve the therapeutic outcome, a new approach called precision medicine or personalized medicine has been proposed and initiated by the U.S. National Institutes of Health. However, the limited availability of effective medications and the high cost are still the major barriers for many cancer patients. Thus alternative approaches such as herbal medicines could be a feasible and less costly option. Unfortunately, scientific evidence for the efficacy of a majority of herbal medicines is still lacking and their development to meet FDA approval or other regulatory agencies is a big challenge. However, herbal medicines may be able to play an important role in precision medicine or personalized medicine. This review will focus on the existing and future technologies that could speed the development of herbal products for treatment of resistant cancer in individual patients. Specifically, it will concentrate on reviewing the phenotypic (activity based) rather than genotypic (mechanism based) approach to develop herbal medicine useful for personalized cancer chemotherapy.

On the use of particle filters for electromagnetic tracking in high dose rate brachytherapy

NASA Astrophysics Data System (ADS)

Götz, Th I.; Lahmer, G.; Brandt, T.; Kallis, K.; Strnad, V.; Bert, Ch; Hensel, B.; Tomé, A. M.; Lang, E. W.

2017-10-01

Modern radiotherapy of female breast cancers often employs high dose rate brachytherapy, where a radioactive source is moved inside catheters, implanted in the female breast, according to a prescribed treatment plan. Source localization relative to the patient’s anatomy is determined with solenoid sensors whose spatial positions are measured with an electromagnetic tracking system. Precise sensor dwell position determination is of utmost importance to assure irradiation of the cancerous tissue according to the treatment plan. We present a hybrid data analysis system which combines multi-dimensional scaling with particle filters to precisely determine sensor dwell positions in the catheters during subsequent radiation treatment sessions. Both techniques are complemented with empirical mode decomposition for the removal of superimposed breathing artifacts. We show that the hybrid model robustly and reliably determines the spatial positions of all catheters used during the treatment and precisely determines any deviations of actual sensor dwell positions from the treatment plan. The hybrid system only relies on sensor positions measured with an EMT system and relates them to the spatial positions of the implanted catheters as initially determined with a computed x-ray tomography.

Impact of orbit, clock and EOP errors in GNSS Precise Point Positioning

NASA Astrophysics Data System (ADS)

Hackman, C.

2012-12-01

Precise point positioning (PPP; [1]) has gained ever-increasing usage in GNSS carrier-phase positioning, navigation and timing (PNT) since its inception in the late 1990s. In this technique, high-precision satellite clocks, satellite ephemerides and earth-orientation parameters (EOPs) are applied as fixed input by the user in order to estimate receiver/location-specific quantities such as antenna coordinates, troposphere delay and receiver-clock corrections. This is in contrast to "network" solutions, in which (typically) less-precise satellite clocks, satellite ephemerides and EOPs are used as input, and in which these parameters are estimated simultaneously with the receiver/location-specific parameters. The primary reason for increased PPP application is that it offers most of the benefits of a network solution with a smaller computing cost. In addition, the software required to do PPP positioning can be simpler than that required for network solutions. Finally, PPP permits high-precision positioning of single or sparsely spaced receivers that may have few or no GNSS satellites in common view. A drawback of PPP is that the accuracy of the results depend directly on the accuracy of the supplied orbits, clocks and EOPs, since these parameters are not adjusted during the processing. In this study, we will examine the impact of orbit, EOP and satellite clock estimates on PPP solutions. Our primary focus will be the impact of these errors on station coordinates; however the study may be extended to error propagation into receiver-clock corrections and/or troposphere estimates if time permits. Study motivation: the United States Naval Observatory (USNO) began testing PPP processing using its own predicted orbits, clocks and EOPs in Summer 2012 [2]. The results of such processing could be useful for real- or near-real-time applications should they meet accuracy/precision requirements. Understanding how errors in satellite clocks, satellite orbits and EOPs propagate into PPP positioning and timing results allows researchers to focus their improvement efforts in areas most in need of attention. The initial study will be conducted using the simulation capabilities of Bernese GPS Software and extended to using real data if time permits. [1] J.F. Zumberge, M.B. Heflin, D.C. Jefferson, M.M. Watkins and F.H. Webb, Precise point positioning for the efficient and robust analysis of GPS data from large networks, J. Geophys. Res., 102(B3), 5005-5017, doi:10.1029/96JB03860, 1997. [2] C. Hackman, S.M. Byram, V.J. Slabinski and J.C. Tracey, Near-real-time and other high-precision GNSS-based orbit/clock/earth-orientation/troposphere parameters available from USNO, Proc. 2012 ION Joint Navigation Conference, 15 pp., in press, 2012.

Mapping stream habitats with a global positioning system: Accuracy, precision, and comparison with traditional methods

USGS Publications Warehouse

Dauwalter, D.C.; Fisher, W.L.; Belt, K.C.

2006-01-01

We tested the precision and accuracy of the Trimble GeoXT??? global positioning system (GPS) handheld receiver on point and area features and compared estimates of stream habitat dimensions (e.g., lengths and areas of riffles and pools) that were made in three different Oklahoma streams using the GPS receiver and a tape measure. The precision of differentially corrected GPS (DGPS) points was not affected by the number of GPS position fixes (i.e., geographic location estimates) averaged per DGPS point. Horizontal error of points ranged from 0.03 to 2.77 m and did not differ with the number of position fixes per point. The error of area measurements ranged from 0.1% to 110.1% but decreased as the area increased. Again, error was independent of the number of position fixes averaged per polygon corner. The estimates of habitat lengths, widths, and areas did not differ when measured using two methods of data collection (GPS and a tape measure), nor did the differences among methods change at three stream sites with contrasting morphologies. Measuring features with a GPS receiver was up to 3.3 times faster on average than using a tape measure, although signal interference from high streambanks or overhanging vegetation occasionally limited satellite signal availability and prolonged measurements with a GPS receiver. There were also no differences in precision of habitat dimensions when mapped using a continuous versus a position fix average GPS data collection method. Despite there being some disadvantages to using the GPS in stream habitat studies, measuring stream habitats with a GPS resulted in spatially referenced data that allowed the assessment of relative habitat position and changes in habitats over time, and was often faster than using a tape measure. For most spatial scales of interest, the precision and accuracy of DGPS data are adequate and have logistical advantages when compared to traditional methods of measurement. ?? 2006 Springer Science+Business Media, Inc.

Advances in the Control System for a High Precision Dissolved Organic Carbon Analyzer

NASA Astrophysics Data System (ADS)

Liao, M.; Stubbins, A.; Haidekker, M.

2017-12-01

Dissolved organic carbon (DOC) is a master variable in aquatic ecosystems. DOC in the ocean is one of the largest carbon stores on earth. Studies of the dynamics of DOC in the ocean and other low DOC systems (e.g. groundwater) are hindered by the lack of high precision (sub-micromolar) analytical techniques. Results are presented from efforts to construct and optimize a flow-through, wet chemical DOC analyzer. This study focused on the design, integration and optimization of high precision components and control systems required for such a system (mass flow controller, syringe pumps, gas extraction, reactor chamber with controlled UV and temperature). Results of the approaches developed are presented.

Precise positioning with current multi-constellation Global Navigation Satellite Systems: GPS, GLONASS, Galileo and BeiDou.

PubMed

Li, Xingxing; Zhang, Xiaohong; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

2015-02-09

The world of satellite navigation is undergoing dramatic changes with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs). At the moment more than 70 satellites are already in view, and about 120 satellites will be available once all four systems (BeiDou + Galileo + GLONASS + GPS) are fully deployed in the next few years. This will bring great opportunities and challenges for both scientific and engineering applications. In this paper we develop a four-system positioning model to make full use of all available observations from different GNSSs. The significant improvement of satellite visibility, spatial geometry, dilution of precision, convergence, accuracy, continuity and reliability that a combining utilization of multi-GNSS brings to precise positioning are carefully analyzed and evaluated, especially in constrained environments.

Validating regulatory predictions from diverse bacteria with mutant fitness data

DOE PAGES

Sagawa, Shiori; Price, Morgan N.; Deutschbauer, Adam M.; ...

2017-05-24

Although transcriptional regulation is fundamental to understanding bacterial physiology, the targets of most bacterial transcription factors are not known. Comparative genomics has been used to identify likely targets of some of these transcription factors, but these predictions typically lack experimental support. Here, we used mutant fitness data, which measures the importance of each gene for a bacterium's growth across many conditions, to test regulatory predictions from RegPrecise, a curated collection of comparative genomics predictions. Because characterized transcription factors often have correlated fitness with one of their targets (either positively or negatively), correlated fitness patterns provide support for the comparative genomicsmore » predictions. At a false discovery rate of 3%, we identified significant cofitness for at least one target of 158 TFs in 107 ortholog groups and from 24 bacteria. Thus, high-throughput genetics can be used to identify a high-confidence subset of the sequence-based regulatory predictions.« less

Validating regulatory predictions from diverse bacteria with mutant fitness data

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

Sagawa, Shiori; Price, Morgan N.; Deutschbauer, Adam M.

Although transcriptional regulation is fundamental to understanding bacterial physiology, the targets of most bacterial transcription factors are not known. Comparative genomics has been used to identify likely targets of some of these transcription factors, but these predictions typically lack experimental support. Here, we used mutant fitness data, which measures the importance of each gene for a bacterium's growth across many conditions, to test regulatory predictions from RegPrecise, a curated collection of comparative genomics predictions. Because characterized transcription factors often have correlated fitness with one of their targets (either positively or negatively), correlated fitness patterns provide support for the comparative genomicsmore » predictions. At a false discovery rate of 3%, we identified significant cofitness for at least one target of 158 TFs in 107 ortholog groups and from 24 bacteria. Thus, high-throughput genetics can be used to identify a high-confidence subset of the sequence-based regulatory predictions.« less

Between-Region Genetic Divergence Reflects the Mode and Tempo of Tumor Evolution

PubMed Central

Sun, Ruping; Hu, Zheng; Sottoriva, Andrea; Graham, Trevor A.; Harpak, Arbel; Ma, Zhicheng; Fischer, Jared M.; Shibata, Darryl; Curtis, Christina

2017-01-01

Given the implications of tumor dynamics for precision medicine, there is a need to systematically characterize the mode of evolution across diverse solid tumor types. In particular, methods to infer the role of natural selection within established human tumors are lacking. By simulating spatial tumor growth under different evolutionary modes and examining patterns of between-region subclonal genetic divergence from multi-region sequencing (MRS) data, we demonstrate that it is feasible to distinguish tumors driven by strong positive subclonal selection from those evolving neutrally or under weak selection, as the latter fail to dramatically alter subclonal composition. We developed a classifier based on measures of between-region subclonal genetic divergence and projected patient data into model space, revealing different modes of evolution both within and between solid tumor types. Our findings have broad implications for how human tumors progress, accumulate intra-tumor heterogeneity, and ultimately how they may be more effectively treated. PMID:28581503

Optical micromanipulation of nanoparticles and cells inside living zebrafish.

PubMed

Johansen, Patrick Lie; Fenaroli, Federico; Evensen, Lasse; Griffiths, Gareth; Koster, Gerbrand

2016-03-21

Regulation of biological processes is often based on physical interactions between cells and their microenvironment. To unravel how and where interactions occur, micromanipulation methods can be used that offer high-precision control over the duration, position and magnitude of interactions. However, lacking an in vivo system, micromanipulation has generally been done with cells in vitro, which may not reflect the complex in vivo situation inside multicellular organisms. Here using optical tweezers we demonstrate micromanipulation throughout the transparent zebrafish embryo. We show that different cells, as well as injected nanoparticles and bacteria can be trapped and that adhesion properties and membrane deformation of endothelium and macrophages can be analysed. This non-invasive micromanipulation inside a whole-organism gives direct insights into cell interactions that are not accessible using existing approaches. Potential applications include screening of nanoparticle-cell interactions for cancer therapy or tissue invasion studies in cancer and infection biology.

The reproducibility of research and the misinterpretation of p-values

PubMed Central

2017-01-01

We wish to answer this question: If you observe a ‘significant’ p-value after doing a single unbiased experiment, what is the probability that your result is a false positive? The weak evidence provided by p-values between 0.01 and 0.05 is explored by exact calculations of false positive risks. When you observe p = 0.05, the odds in favour of there being a real effect (given by the likelihood ratio) are about 3 : 1. This is far weaker evidence than the odds of 19 to 1 that might, wrongly, be inferred from the p-value. And if you want to limit the false positive risk to 5%, you would have to assume that you were 87% sure that there was a real effect before the experiment was done. If you observe p = 0.001 in a well-powered experiment, it gives a likelihood ratio of almost 100 : 1 odds on there being a real effect. That would usually be regarded as conclusive. But the false positive risk would still be 8% if the prior probability of a real effect were only 0.1. And, in this case, if you wanted to achieve a false positive risk of 5% you would need to observe p = 0.00045. It is recommended that the terms ‘significant’ and ‘non-significant’ should never be used. Rather, p-values should be supplemented by specifying the prior probability that would be needed to produce a specified (e.g. 5%) false positive risk. It may also be helpful to specify the minimum false positive risk associated with the observed p-value. Despite decades of warnings, many areas of science still insist on labelling a result of p < 0.05 as ‘statistically significant’. This practice must contribute to the lack of reproducibility in some areas of science. This is before you get to the many other well-known problems, like multiple comparisons, lack of randomization and p-hacking. Precise inductive inference is impossible and replication is the only way to be sure. Science is endangered by statistical misunderstanding, and by senior people who impose perverse incentives on scientists. PMID:29308247

Precise computer controlled positioning of robot end effectors using force sensors

NASA Technical Reports Server (NTRS)

Shieh, L. S.; Mcinnis, B. C.; Wang, J. C.

1988-01-01

A thorough study of combined position/force control using sensory feedback for a one-dimensional manipulator model, which may count for the spacecraft docking problem or be extended to the multi-joint robot manipulator problem, was performed. The additional degree of freedom introduced by the compliant force sensor is included in the system dynamics in the design of precise position control. State feedback based on the pole placement method and with integral control is used to design the position controller. A simple constant gain force controller is used as an example to illustrate the dependence of the stability and steady-state accuracy of the overall position/force control upon the design of the inner position controller. Supportive simulation results are also provided.

Instantaneous Real-Time Kinematic Decimeter-Level Positioning with BeiDou Triple-Frequency Signals over Medium Baselines.

PubMed

He, Xiyang; Zhang, Xiaohong; Tang, Long; Liu, Wanke

2015-12-22

Many applications, such as marine navigation, land vehicles location, etc., require real time precise positioning under medium or long baseline conditions. In this contribution, we develop a model of real-time kinematic decimeter-level positioning with BeiDou Navigation Satellite System (BDS) triple-frequency signals over medium distances. The ambiguities of two extra-wide-lane (EWL) combinations are fixed first, and then a wide lane (WL) combination is reformed based on the two EWL combinations for positioning. Theoretical analysis and empirical analysis is given of the ambiguity fixing rate and the positioning accuracy of the presented method. The results indicate that the ambiguity fixing rate can be up to more than 98% when using BDS medium baseline observations, which is much higher than that of dual-frequency Hatch-Melbourne-Wübbena (HMW) method. As for positioning accuracy, decimeter level accuracy can be achieved with this method, which is comparable to that of carrier-smoothed code differential positioning method. Signal interruption simulation experiment indicates that the proposed method can realize fast high-precision positioning whereas the carrier-smoothed code differential positioning method needs several hundreds of seconds for obtaining high precision results. We can conclude that a relatively high accuracy and high fixing rate can be achieved for triple-frequency WL method with single-epoch observations, displaying significant advantage comparing to traditional carrier-smoothed code differential positioning method.

Science 101: How Do Atomic Clocks Work?

ERIC Educational Resources Information Center

Science and Children, 2008

2008-01-01

You might be wondering why in the world we need such precise measures of time. Well, many systems we use everyday, such as Global Positioning Systems, require precise synchronization of time. This comes into play in telecommunications and wireless communications, also. For purely scientific reasons, we can use precise measurement of time to…

Precise FIA plot registration using field and dense LIDAR data

Treesearch

Demetrios Gatziolis

2009-01-01

Precise registration of forest inventory and analysis (FIA) plots is a prerequisite for an effective fusion of field data with ancillary spatial information, which is an approach commonly employed in the mapping of various forest parameters. Although the adoption of Global Positioning System technology has improved the precision of plot coordinates obtained during...

Helicopter precision approach capability using the Global Positioning System

NASA Technical Reports Server (NTRS)

Kaufmann, David N.

1992-01-01

The period between 1 July and 31 December, 1992, was spent developing a research plan as well as a navigation system document and flight test plan to investigate helicopter precision approach capability using the Global Positioning System (GPS). In addition, all hardware and software required for the research was acquired, developed, installed, and verified on both the test aircraft and the ground-based reference station.

Performance Analysis of Beidou-2/Beidou-3e Combined Solution with Emphasis on Precise Orbit Determination and Precise Point Positioning

PubMed Central

Xu, Xiaolong; Li, Min; Li, Wenwen; Liu, Jingnan

2018-01-01

In 2015, the plan for global coverage by the Chinese BeiDou Navigation Satellite System was launched. Five global BeiDou experimental satellites (BeiDou-3e) are in orbit for testing. To analyze the performances of precise orbit determination (POD) and precise point positioning (PPP) of onboard BeiDou satellites, about two months of data from 24 tracking stations were used. According to quality analysis of BeiDou-2/BeiDou-3e data, there is no satellite-induced code bias in BeiDou-3e satellites, which has been found in BeiDou-2 satellites. This phenomenon indicates that the quality issues of pseudorange data in BeiDou satellites have been solved well. POD results indicate that the BeiDou-3e orbit precision is comparable to that of BeiDou-2 satellites. The ambiguity fixed solution improved the orbit consistency of inclined geosynchronous orbit satellites in along-track and cross-track directions, but had little effect in the radial direction. Satellite laser ranging of BeiDou-3e medium Earth orbit satellites (MEOs) achieved a standard deviation of about 4 cm. Differences in clock offset series after the removal of reference clock in overlapping arcs were used to assess clock quality, and standard deviation of clock offset could reach 0.18 ns on average, which was in agreement with the orbit precision. For static PPP, when BeiDou-3e satellites were included, the positioning performance for horizontal components was improved slightly. For kinematic PPP, when global positioning satellites (GPS) were combined with BeiDou-2 and BeiDou-3e satellites, the convergence time was 13.5 min with a precision of 2–3 cm for horizontal components, and 3–4 cm for the vertical component. PMID:29304000

Accurate reconstruction of viral quasispecies spectra through improved estimation of strain richness

PubMed Central

2015-01-01

Background Estimating the number of different species (richness) in a mixed microbial population has been a main focus in metagenomic research. Existing methods of species richness estimation ride on the assumption that the reads in each assembled contig correspond to only one of the microbial genomes in the population. This assumption and the underlying probabilistic formulations of existing methods are not useful for quasispecies populations where the strains are highly genetically related. The lack of knowledge on the number of different strains in a quasispecies population is observed to hinder the precision of existing Viral Quasispecies Spectrum Reconstruction (QSR) methods due to the uncontrolled reconstruction of a large number of in silico false positives. In this work, we formulated a novel probabilistic method for strain richness estimation specifically targeting viral quasispecies. By using this approach we improved our recently proposed spectrum reconstruction pipeline ViQuaS to achieve higher levels of precision in reconstructed quasispecies spectra without compromising the recall rates. We also discuss how one other existing popular QSR method named ShoRAH can be improved using this new approach. Results On benchmark data sets, our estimation method provided accurate richness estimates (< 0.2 median estimation error) and improved the precision of ViQuaS by 2%-13% and F-score by 1%-9% without compromising the recall rates. We also demonstrate that our estimation method can be used to improve the precision and F-score of ShoRAH by 0%-7% and 0%-5% respectively. Conclusions The proposed probabilistic estimation method can be used to estimate the richness of viral populations with a quasispecies behavior and to improve the accuracy of the quasispecies spectra reconstructed by the existing methods ViQuaS and ShoRAH in the presence of a moderate level of technical sequencing errors. Availability http://sourceforge.net/projects/viquas/ PMID:26678073

Genome-Wide Association Study of Meat Quality Traits in a White Duroc×Erhualian F2 Intercross and Chinese Sutai Pigs

PubMed Central

Ma, Junwu; Yang, Jie; Zhou, Lisheng; Zhang, Zhiyan; Ma, Huanban; Xie, Xianhua; Zhang, Feng; Xiong, Xinwei; Cui, Leilei; Yang, Hui; Liu, Xianxian; Duan, Yanyu; Xiao, Shijun; Ai, Huashui; Ren, Jun; Huang, Lusheng

2013-01-01

Thousands of QTLs for meat quality traits have been identified by linkage mapping studies, but most of them lack precise position or replication between populations, which hinder their application in pig breeding programs. To localize QTLs for meat quality traits to precise genomic regions, we performed a genome-wide association (GWA) study using the Illumina PorcineSNP60K Beadchip in two swine populations: 434 Sutai pigs and 933 F2 pigs from a White Duroc×Erhualian intercross. Meat quality traits, including pH, color, drip loss, moisture content, protein content and intramuscular fat content (IMF), marbling and firmness scores in the M. longissimus (LM) and M. semimembranosus (SM) muscles, were recorded on the two populations. In total, 127 chromosome-wide significant SNPs for these traits were identified. Among them, 11 SNPs reached genome-wise significance level, including 1 on SSC3 for pH, 1 on SSC3 and 3 on SSC15 for drip loss, 3 (unmapped) for color a*, and 2 for IMF each on SSC9 and SSCX. Except for 11 unmapped SNPs, 116 significant SNPs fell into 28 genomic regions of approximately 10 Mb or less. Most of these regions corresponded to previously reported QTL regions and spanned smaller intervals than before. The loci on SSC3 and SSC7 appeared to have pleiotropic effects on several related traits. Besides them, a few QTL signals were replicated between the two populations. Further, we identified thirteen new candidate genes for IMF, marbling and firmness, on the basis of their positions, functional annotations and reported expression patterns. The findings will contribute to further identification of the causal mutation underlying these QTLs and future marker-assisted selection in pigs. PMID:23724019

Solving the Orientation Specific Constraints in Transcranial Magnetic Stimulation by Rotating Fields

PubMed Central

Neef, Nicole E.; Agudelo-Toro, Andres; Rakhmilevitch, David; Paulus, Walter; Moses, Elisha

2014-01-01

Transcranial Magnetic Stimulation (TMS) is a promising technology for both neurology and psychiatry. Positive treatment outcome has been reported, for instance in double blind, multi-center studies on depression. Nonetheless, the application of TMS towards studying and treating brain disorders is still limited by inter-subject variability and lack of model systems accessible to TMS. The latter are required to obtain a deeper understanding of the biophysical foundations of TMS so that the stimulus protocol can be optimized for maximal brain response, while inter-subject variability hinders precise and reliable delivery of stimuli across subjects. Recent studies showed that both of these limitations are in part due to the angular sensitivity of TMS. Thus, a technique that would eradicate the need for precise angular orientation of the coil would improve both the inter-subject reliability of TMS and its effectiveness in model systems. We show here how rotation of the stimulating field relieves the angular sensitivity of TMS and provides improvements in both issues. Field rotation is attained by superposing the fields of two coils positioned orthogonal to each other and operated with a relative phase shift in time. Rotating field TMS (rfTMS) efficiently stimulates both cultured hippocampal networks and rat motor cortex, two neuronal systems that are notoriously difficult to excite magnetically. This opens the possibility of pharmacological and invasive TMS experiments in these model systems. Application of rfTMS to human subjects overcomes the orientation dependence of standard TMS. Thus, rfTMS yields optimal targeting of brain regions where correct orientation cannot be determined (e.g., via motor feedback) and will enable stimulation in brain regions where a preferred axonal orientation does not exist. PMID:24505266

PreCisIon: PREdiction of CIS-regulatory elements improved by gene's positION.

PubMed

Elati, Mohamed; Nicolle, Rémy; Junier, Ivan; Fernández, David; Fekih, Rim; Font, Julio; Képès, François

2013-02-01

Conventional approaches to predict transcriptional regulatory interactions usually rely on the definition of a shared motif sequence on the target genes of a transcription factor (TF). These efforts have been frustrated by the limited availability and accuracy of TF binding site motifs, usually represented as position-specific scoring matrices, which may match large numbers of sites and produce an unreliable list of target genes. To improve the prediction of binding sites, we propose to additionally use the unrelated knowledge of the genome layout. Indeed, it has been shown that co-regulated genes tend to be either neighbors or periodically spaced along the whole chromosome. This study demonstrates that respective gene positioning carries significant information. This novel type of information is combined with traditional sequence information by a machine learning algorithm called PreCisIon. To optimize this combination, PreCisIon builds a strong gene target classifier by adaptively combining weak classifiers based on either local binding sequence or global gene position. This strategy generically paves the way to the optimized incorporation of any future advances in gene target prediction based on local sequence, genome layout or on novel criteria. With the current state of the art, PreCisIon consistently improves methods based on sequence information only. This is shown by implementing a cross-validation analysis of the 20 major TFs from two phylogenetically remote model organisms. For Bacillus subtilis and Escherichia coli, respectively, PreCisIon achieves on average an area under the receiver operating characteristic curve of 70 and 60%, a sensitivity of 80 and 70% and a specificity of 60 and 56%. The newly predicted gene targets are demonstrated to be functionally consistent with previously known targets, as assessed by analysis of Gene Ontology enrichment or of the relevant literature and databases.

Estimation of satellite position, clock and phase bias corrections

NASA Astrophysics Data System (ADS)

Henkel, Patrick; Psychas, Dimitrios; Günther, Christoph; Hugentobler, Urs

2018-05-01

Precise point positioning with integer ambiguity resolution requires precise knowledge of satellite position, clock and phase bias corrections. In this paper, a method for the estimation of these parameters with a global network of reference stations is presented. The method processes uncombined and undifferenced measurements of an arbitrary number of frequencies such that the obtained satellite position, clock and bias corrections can be used for any type of differenced and/or combined measurements. We perform a clustering of reference stations. The clustering enables a common satellite visibility within each cluster and an efficient fixing of the double difference ambiguities within each cluster. Additionally, the double difference ambiguities between the reference stations of different clusters are fixed. We use an integer decorrelation for ambiguity fixing in dense global networks. The performance of the proposed method is analysed with both simulated Galileo measurements on E1 and E5a and real GPS measurements of the IGS network. We defined 16 clusters and obtained satellite position, clock and phase bias corrections with a precision of better than 2 cm.

High spatial precision nano-imaging of polarization-sensitive plasmonic particles

NASA Astrophysics Data System (ADS)

Liu, Yunbo; Wang, Yipei; Lee, Somin Eunice

2018-02-01

Precise polarimetric imaging of polarization-sensitive nanoparticles is essential for resolving their accurate spatial positions beyond the diffraction limit. However, conventional technologies currently suffer from beam deviation errors which cannot be corrected beyond the diffraction limit. To overcome this issue, we experimentally demonstrate a spatially stable nano-imaging system for polarization-sensitive nanoparticles. In this study, we show that by integrating a voltage-tunable imaging variable polarizer with optical microscopy, we are able to suppress beam deviation errors. We expect that this nano-imaging system should allow for acquisition of accurate positional and polarization information from individual nanoparticles in applications where real-time, high precision spatial information is required.

Analysis and Testing of a LIDAR-Based Approach to Terrain Relative Navigation for Precise Lunar Landing

NASA Technical Reports Server (NTRS)

Johnson, Andrew E.; Ivanov, Tonislav I.

2011-01-01

To increase safety and land near pre-deployed resources, future NASA missions to the moon will require precision landing. A LIDAR-based terrain relative navigation (TRN) approach can achieve precision landing under any lighting conditions. This paper presents results from processing flash lidar and laser altimeter field test data that show LIDAR TRN can obtain position estimates less than 90m while automatically detecting and eliminating incorrect measurements using internal metrics on terrain relief and data correlation. Sensitivity studies show that the algorithm has no degradation in matching performance with initial position uncertainties up to 1.6 km

An application framework for computer-aided patient positioning in radiation therapy.

PubMed

Liebler, T; Hub, M; Sanner, C; Schlegel, W

2003-09-01

The importance of exact patient positioning in radiation therapy increases with the ongoing improvements in irradiation planning and treatment. Therefore, new ways to overcome precision limitations of current positioning methods in fractionated treatment have to be found. The Department of Medical Physics at the German Cancer Research Centre (DKFZ) follows different video-based approaches to increase repositioning precision. In this context, the modular software framework FIVE (Fast Integrated Video-based Environment) has been designed and implemented. It is both hardware- and platform-independent and supports merging position data by integrating various computer-aided patient positioning methods. A highly precise optical tracking system and several subtraction imaging techniques have been realized as modules to supply basic video-based repositioning techniques. This paper describes the common framework architecture, the main software modules and their interfaces. An object-oriented software engineering process has been applied using the UML, C + + and the Qt library. The significance of the current framework prototype for the application in patient positioning as well as the extension to further application areas will be discussed. Particularly in experimental research, where special system adjustments are often necessary, the open design of the software allows problem-oriented extensions and adaptations.

Precise positioning with current multi-constellation Global Navigation Satellite Systems: GPS, GLONASS, Galileo and BeiDou

PubMed Central

Li, Xingxing; Zhang, Xiaohong; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

2015-01-01

The world of satellite navigation is undergoing dramatic changes with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs). At the moment more than 70 satellites are already in view, and about 120 satellites will be available once all four systems (BeiDou + Galileo + GLONASS + GPS) are fully deployed in the next few years. This will bring great opportunities and challenges for both scientific and engineering applications. In this paper we develop a four-system positioning model to make full use of all available observations from different GNSSs. The significant improvement of satellite visibility, spatial geometry, dilution of precision, convergence, accuracy, continuity and reliability that a combining utilization of multi-GNSS brings to precise positioning are carefully analyzed and evaluated, especially in constrained environments. PMID:25659949

[Femtosecond laser in cataract surgery. A critical appraisal].

PubMed

Menapace, R M; Dick, H B

2014-01-01

The use of femtosecond lasers (FSL) is increasingly spreading in cataract surgery. Potential advantages over standard manual cataract surgery are the superior precision of corneal incisions and capsular openings as well as the reduction of ultrasound energy for lens nucleus work-up. Exact positioning and dimensioning of the anterior capsular opening should help reduce decentration and tilt of the intraocular lens (IOL) optics and thus achieve better target refraction. Together with the possibility to correct low-grade corneal astigmatism by precise arcuate incision, FSL technology is expected to convert cataract surgery from a purely curative into a refractive procedure. Apart from own experiences this review article critically analyses the pertinent literature published so far as well as congress presentations and personal reports of other FSL surgeons. The advantages and disadvantages are scrutinized with regard to their impact on the surgical and refractive results and compared with those experienced by the authors with manual cataract surgery over several decades. Economic and healthcare political aspects are also addressed. The use of FSL surgery improves the precision and reproducibility of corneal incisions and the capsular opening and reduces the amount of ultrasound energy required for lens nucleus work-up. However, the clinical benefits must be put into perspective due to the subsequent surgical manipulation of the incisions (during lens emulsification, aspiration and IOL injection), the lacking possibility to visualize the crystalline lens equator as the reference for correct capsulotomy centration and the relativity of ultrasound energy consumption on the corneal endothelial trauma. This is of particular relevance against the background of the significantly higher costs. Conversely, tears of the anterior capsule edge which, apart from interfering with correct IOL positioning, may entail serious complications presently occur more frequently with all FSL instruments. From the economic and healthcare political viewpoint, thought should be given to the possible acquisition of the cataract surgical business by the industry or investors, as cataract surgery is a high-volume standardized procedure with enormous future potential. This could fundamentally change our currently decentralized and individualized structures and subsequently the steam of patient and make surgeons largely dependent or superfluous.

High-precision radius automatic measurement using laser differential confocal technology

NASA Astrophysics Data System (ADS)

Jiang, Hongwei; Zhao, Weiqian; Yang, Jiamiao; Guo, Yongkui; Xiao, Yang

2015-02-01

A high precision radius automatic measurement method using laser differential confocal technology is proposed. Based on the property of an axial intensity curve that the null point precisely corresponds to the focus of the objective and the bipolar property, the method uses the composite PID (proportional-integral-derivative) control to ensure the steady movement of the motor for process of quick-trigger scanning, and uses least-squares linear fitting to obtain the position of the cat-eye and confocal positions, then calculates the radius of curvature of lens. By setting the number of measure times, precision auto-repeat measurement of the radius of curvature is achieved. The experiment indicates that the method has the measurement accuracy of better than 2 ppm, and the measuring repeatability is better than 0.05 μm. In comparison with the existing manual-single measurement, this method has a high measurement precision, a strong environment anti-interference capability, a better measuring repeatability which is only tenth of former's.

Negative emotion enhances mnemonic precision and subjective feelings of remembering in visual long-term memory.

PubMed

Xie, Weizhen; Zhang, Weiwei

2017-09-01

Negative emotion sometimes enhances memory (higher accuracy and/or vividness, e.g., flashbulb memories). The present study investigates whether it is the qualitative (precision) or quantitative (the probability of successful retrieval) aspect of memory that drives these effects. In a visual long-term memory task, observers memorized colors (Experiment 1a) or orientations (Experiment 1b) of sequentially presented everyday objects under negative, neutral, or positive emotions induced with International Affective Picture System images. In a subsequent test phase, observers reconstructed objects' colors or orientations using the method of adjustment. We found that mnemonic precision was enhanced under the negative condition relative to the neutral and positive conditions. In contrast, the probability of successful retrieval was comparable across the emotion conditions. Furthermore, the boost in memory precision was associated with elevated subjective feelings of remembering (vividness and confidence) and metacognitive sensitivity in Experiment 2. Altogether, these findings suggest a novel precision-based account for emotional memories. Copyright © 2017 Elsevier B.V. All rights reserved.

CCD Centroiding Experiment for Correcting a Distorted Image on the Focal Plane

NASA Astrophysics Data System (ADS)

Yano, Taihei; Araki, Hiroshi; Gouda, Naoteru; Kobayashi, Yukiyasu; Tsujimoto, Takuji; Nakajima, Tadashi; Kawano, Nobuyuki; Tazawa, Seiichi; Yamada, Yoshiyuki; Hanada, Hideo; Asari, Kazuyoshi; Tsuruta, Seiitsu

2006-10-01

JASMINE (Japan Astrometry Satellite Mission for Infrared Exploration) and ILOM (In situ Lunar Orientation Measurement) are space missions that are in progress at the National Astronomical Observatory of Japan. These two projects require a common astrometric technique to obtain precise positions of star images on solid-state detectors in order to accomplish their objectives. In the laboratory, we have carried out measurements of the centroid of artificial star images on a CCD array in order to investigate the precision of the positions of the stars, using an algorithm for estimating them from photon-weighted means of the stars. In the calibration of the position of a star image at the focal plane, we have also taken into account the lowest order distortion due to optical aberrations, which is proportional to the cube of the distance from the optical axis. Accordingly, we find that the precision of the measurement for the positions of the stars reaches below 1/100 pixel for one measurement.

Measuring true localization accuracy in super resolution microscopy with DNA-origami nanostructures

NASA Astrophysics Data System (ADS)

Reuss, Matthias; Fördős, Ferenc; Blom, Hans; Öktem, Ozan; Högberg, Björn; Brismar, Hjalmar

2017-02-01

A common method to assess the performance of (super resolution) microscopes is to use the localization precision of emitters as an estimate for the achieved resolution. Naturally, this is widely used in super resolution methods based on single molecule stochastic switching. This concept suffers from the fact that it is hard to calibrate measures against a real sample (a phantom), because true absolute positions of emitters are almost always unknown. For this reason, resolution estimates are potentially biased in an image since one is blind to true position accuracy, i.e. deviation in position measurement from true positions. We have solved this issue by imaging nanorods fabricated with DNA-origami. The nanorods used are designed to have emitters attached at each end in a well-defined and highly conserved distance. These structures are widely used to gauge localization precision. Here, we additionally determined the true achievable localization accuracy and compared this figure of merit to localization precision values for two common super resolution microscope methods STED and STORM.

Fabrication of carbon quantum dots with nano-defined position and pattern in one step via sugar-electron-beam writing.

PubMed

Weng, Yuyan; Li, Zhiyun; Peng, Lun; Zhang, Weidong; Chen, Gaojian

2017-12-14

Quantum dots (QDs) are promising materials in nanophotonics, biological imaging, and even quantum computing. Precise positioning and patterning of QDs is a prerequisite for realizing their actual applications. Contrary to the traditional two discrete steps of fabricating and positioning QDs, herein, a novel sugar-electron-beam writing (SEW) method is reported for producing QDs via electron-beam lithography (EBL) that uses a carefully chosen synthetic resist, poly(2-(methacrylamido)glucopyranose) (PMAG). Carbon QDs (CQDs) could be fabricated in situ through electron beam exposure, and the nanoscale position and luminescence intensity of the produced CQDs could be precisely controlled without the assistance of any other fluorescent matter. We have demonstrated that upon combining an electron beam with a glycopolymer, in situ production of CQDs occurs at the electron beam spot center with nanoscale precision at any place and with any patterns, an advancement that we believe will stimulate innovations in future applications.

Collaborated measurement of three-dimensional position and orientation errors of assembled miniature devices with two vision systems

NASA Astrophysics Data System (ADS)

Wang, Xiaodong; Zhang, Wei; Luo, Yi; Yang, Weimin; Chen, Liang

2013-01-01

In assembly of miniature devices, the position and orientation of the parts to be assembled should be guaranteed during or after assembly. In some cases, the relative position or orientation errors among the parts can not be measured from only one direction using visual method, because of visual occlusion or for the features of parts located in a three-dimensional way. An automatic assembly system for precise miniature devices is introduced. In the modular assembly system, two machine vision systems were employed for measurement of the three-dimensionally distributed assembly errors. High resolution CCD cameras and high position repeatability precision stages were integrated to realize high precision measurement in large work space. The two cameras worked in collaboration in measurement procedure to eliminate the influence of movement errors of the rotational or translational stages. A set of templates were designed for calibration of the vision systems and evaluation of the system's measurement accuracy.

Integration of radar altimeter, precision navigation, and digital terrain data for low-altitude flight

NASA Technical Reports Server (NTRS)

Zelenka, Richard E.

1992-01-01

Avionic systems that depend on digitized terrain elevation data for guidance generation or navigational reference require accurate absolute and relative distance measurements to the terrain, especially as they approach lower altitudes. This is particularly exacting in low-altitude helicopter missions, where aggressive terrain hugging maneuvers create minimal horizontal and vertical clearances and demand precise terrain positioning. Sole reliance on airborne precision navigation and stored terrain elevation data for above-ground-level (AGL) positioning severely limits the operational altitude of such systems. A Kalman filter is presented which blends radar altimeter returns, precision navigation, and stored terrain elevation data for AGL positioning. The filter is evaluated using low-altitude helicopter flight test data acquired over moderately rugged terrain. The proposed Kalman filter is found to remove large disparities in predicted AGL altitude (i.e., from airborne navigation and terrain elevation data) in the presence of measurement anomalies and dropouts. Previous work suggested a minimum clearance altitude of 220 ft AGL for a near-terrain guidance system; integration of a radar altimeter allows for operation of that system below 50 ft, subject to obstacle-avoidance limitations.

Precision mechatronics based on high-precision measuring and positioning systems and machines

NASA Astrophysics Data System (ADS)

Jäger, Gerd; Manske, Eberhard; Hausotte, Tino; Mastylo, Rostyslav; Dorozhovets, Natalja; Hofmann, Norbert

2007-06-01

Precision mechatronics is defined in the paper as the science and engineering of a new generation of high precision systems and machines. Nanomeasuring and nanopositioning engineering represents important fields of precision mechatronics. The nanometrology is described as the today's limit of the precision engineering. The problem, how to design nanopositioning machines with uncertainties as small as possible will be discussed. The integration of several optical and tactile nanoprobes makes the 3D-nanopositioning machine suitable for various tasks, such as long range scanning probe microscopy, mask and wafer inspection, nanotribology, nanoindentation, free form surface measurement as well as measurement of microoptics, precision molds, microgears, ring gauges and small holes.

Field precision machining technology of target chamber in ICF lasers

NASA Astrophysics Data System (ADS)

Xu, Yuanli; Wu, Wenkai; Shi, Sucun; Duan, Lin; Chen, Gang; Wang, Baoxu; Song, Yugang; Liu, Huilin; Zhu, Mingzhi

2016-10-01

In ICF lasers, many independent laser beams are required to be positioned on target with a very high degree of accuracy during a shot. The target chamber provides a precision platform and datum reference for final optics assembly and target collimation and location system. The target chamber consists of shell with welded flanges, reinforced concrete pedestal, and lateral support structure. The field precision machining technology of target chamber in ICF lasers have been developed based on ShenGuangIII (SGIII). The same center of the target chamber is adopted in the process of design, fabrication, and alignment. The technologies of beam collimation and datum reference transformation are developed for the fabrication, positioning and adjustment of target chamber. A supporting and rotating mechanism and a special drilling machine are developed to bore the holes of ports. An adjustment mechanism is designed to accurately position the target chamber. In order to ensure the collimation requirements of the beam leading and focusing and the target positioning, custom-machined spacers are used to accurately correct the alignment error of the ports. Finally, this paper describes the chamber center, orientation, and centering alignment error measurements of SGIII. The measurements show the field precision machining of SGIII target chamber meet its design requirement. These information can be used on similar systems.

The Paradox of Abstraction: Precision Versus Concreteness

ERIC Educational Resources Information Center

Iliev, Rumen; Axelrod, Robert

2017-01-01

We introduce a novel measure of abstractness based on the amount of information of a concept computed from its position in a semantic taxonomy. We refer to this measure as "precision". We propose two alternative ways to measure precision, one based on the path length from a concept to the root of the taxonomic tree, and another one based…

A New Method of High-Precision Positioning for an Indoor Pseudolite without Using the Known Point Initialization.

PubMed

Zhao, Yinzhi; Zhang, Peng; Guo, Jiming; Li, Xin; Wang, Jinling; Yang, Fei; Wang, Xinzhe

2018-06-20

Due to the great influence of multipath effect, noise, clock and error on pseudorange, the carrier phase double difference equation is widely used in high-precision indoor pseudolite positioning. The initial position is determined mostly by the known point initialization (KPI) method, and then the ambiguities can be fixed with the LAMBDA method. In this paper, a new method without using the KPI to achieve high-precision indoor pseudolite positioning is proposed. The initial coordinates can be quickly obtained to meet the accuracy requirement of the indoor LAMBDA method. The detailed processes of the method follows: Aiming at the low-cost single-frequency pseudolite system, the static differential pseudolite system (DPL) method is used to obtain the low-accuracy positioning coordinates of the rover station quickly. Then, the ambiguity function method (AFM) is used to search for the coordinates in the corresponding epoch. The real coordinates obtained by AFM can meet the initial accuracy requirement of the LAMBDA method, so that the double difference carrier phase ambiguities can be correctly fixed. Following the above steps, high-precision indoor pseudolite positioning can be realized. Several experiments, including static and dynamic tests, are conducted to verify the feasibility of the new method. According to the results of the experiments, the initial coordinates with the accuracy of decimeter level through the DPL can be obtained. For the AFM part, both a one-meter search scope and two-centimeter or four-centimeter search steps are used to ensure the precision at the centimeter level and high search efficiency. After dealing with the problem of multiple peaks caused by the ambiguity cosine function, the coordinate information of the maximum ambiguity function value (AFV) is taken as the initial value of the LAMBDA, and the ambiguities can be fixed quickly. The new method provides accuracies at the centimeter level for dynamic experiments and at the millimeter level for static ones.

A high precision position sensor design and its signal processing algorithm for a maglev train.

PubMed

Xue, Song; Long, Zhiqiang; He, Ning; Chang, Wensen

2012-01-01

High precision positioning technology for a kind of high speed maglev train with an electromagnetic suspension (EMS) system is studied. At first, the basic structure and functions of the position sensor are introduced and some key techniques to enhance the positioning precision are designed. Then, in order to further improve the positioning signal quality and the fault-tolerant ability of the sensor, a new kind of discrete-time tracking differentiator (TD) is proposed based on nonlinear optimal control theory. This new TD has good filtering and differentiating performances and a small calculation load. It is suitable for real-time signal processing. The stability, convergence property and frequency characteristics of the TD are studied and analyzed thoroughly. The delay constant of the TD is figured out and an effective time delay compensation algorithm is proposed. Based on the TD technology, a filtering process is introduced in to improve the positioning signal waveform when the sensor is under bad working conditions, and a two-sensor switching algorithm is designed to eliminate the positioning errors caused by the joint gaps of the long stator. The effectiveness and stability of the sensor and its signal processing algorithms are proved by the experiments on a test train during a long-term test run.

A High Precision Position Sensor Design and Its Signal Processing Algorithm for a Maglev Train

PubMed Central

Xue, Song; Long, Zhiqiang; He, Ning; Chang, Wensen

2012-01-01

High precision positioning technology for a kind of high speed maglev train with an electromagnetic suspension (EMS) system is studied. At first, the basic structure and functions of the position sensor are introduced and some key techniques to enhance the positioning precision are designed. Then, in order to further improve the positioning signal quality and the fault-tolerant ability of the sensor, a new kind of discrete-time tracking differentiator (TD) is proposed based on nonlinear optimal control theory. This new TD has good filtering and differentiating performances and a small calculation load. It is suitable for real-time signal processing. The stability, convergence property and frequency characteristics of the TD are studied and analyzed thoroughly. The delay constant of the TD is figured out and an effective time delay compensation algorithm is proposed. Based on the TD technology, a filtering process is introduced in to improve the positioning signal waveform when the sensor is under bad working conditions, and a two-sensor switching algorithm is designed to eliminate the positioning errors caused by the joint gaps of the long stator. The effectiveness and stability of the sensor and its signal processing algorithms are proved by the experiments on a test train during a long-term test run. PMID:22778582

On Test-Wiseness and Some Related Constructs

ERIC Educational Resources Information Center

Nilsson, Ingvar; Wedman, Ingemar

1976-01-01

States that, due to confusion of concepts and lack of systemization, "previous studies are often difficult to interpret and consequently...afford little possibility of formulating more precise statements about those errors the concepts represent...." A proposal for systematization is presented. (Author/RW)

A roughness-corrected index of relative bed stability for regional stream surveys

EPA Science Inventory

Quantitative regional assessments of streambed sedimentation and its likely causes are hampered because field investigations typically lack the requisite sample size, measurements, or precision for sound geomorphic and statistical interpretation. We adapted an index of relative b...

Bone mineral density of the femoral neck in resurfacing hip arthroplasty

PubMed Central

Ovesen, Ole; Brixen, Kim; Varmarken, Jens-Erik; Overgaard, SØren

2010-01-01

Background and purpose Resurfacing total hip arthroplasty (RTHA) may preserve the femoral neck bone stock postoperatively. Bone mineral density (BMD) may be affected by the hip position, which might bias longitudinal studies. We investigated the dependency of BMD precision on type of ROI and hip position. Method We DXA-scanned the femoral neck of 15 resurfacing patients twice with the hip in 3 different rotations: 15° internal, neutral, and 15° external. For each position, BMD was analyzed with 3 surface area models. One model measured BMD in the total femoral neck, the second model divided the neck in two, and the third model had 6 divisions. Results When all hip positions were pooled, average coefficients of variation (CVs) of 3.1%, 3.6%, and 4.6% were found in the 1-, 2-, and 6-region models, respectively. The externally rotated hip position was less reproducible. When rotating in increments of 15° or 30°, the average CVs rose to 7.2%, 7.3%, and 12% in the 3 models. Rotation affected the precision most in the model that divided the neck in 6 subregions, predominantly in the lateral and distal regions. For larger-region models, some rotation could be allowed without compromising the precision. Interpretation If hip rotation is strictly controlled, DXA can reliably provide detailed topographical information about the BMD changes around an RTHA. As rotation strongly affects the precision of the BMD measurements in small regions, we suggest that a less detailed model should be used for analysis in studies where the leg position has not been firmly controlled. PMID:20367420

The Socio-Moral Image Database (SMID): A novel stimulus set for the study of social, moral and affective processes.

PubMed

Crone, Damien L; Bode, Stefan; Murawski, Carsten; Laham, Simon M

2018-01-01

A major obstacle for the design of rigorous, reproducible studies in moral psychology is the lack of suitable stimulus sets. Here, we present the Socio-Moral Image Database (SMID), the largest standardized moral stimulus set assembled to date, containing 2,941 freely available photographic images, representing a wide range of morally (and affectively) positive, negative and neutral content. The SMID was validated with over 820,525 individual judgments from 2,716 participants, with normative ratings currently available for all images on affective valence and arousal, moral wrongness, and relevance to each of the five moral values posited by Moral Foundations Theory. We present a thorough analysis of the SMID regarding (1) inter-rater consensus, (2) rating precision, and (3) breadth and variability of moral content. Additionally, we provide recommendations for use aimed at efficient study design and reproducibility, and outline planned extensions to the database. We anticipate that the SMID will serve as a useful resource for psychological, neuroscientific and computational (e.g., natural language processing or computer vision) investigations of social, moral and affective processes. The SMID images, along with associated normative data and additional resources are available at https://osf.io/2rqad/.

Measurement of liquid film thickness by optical fluorescence and its application to an oscillating piston positive displacement flowmeter

NASA Astrophysics Data System (ADS)

Morton, Charlotte E.; Baker, Roger C.; Hutchings, Ian M.

2011-12-01

The movement of the circular piston in an oscillating piston positive displacement flowmeter is important in understanding the operation of the flowmeter, and the leakage of liquid past the piston plays a key role in the performance of the meter. The clearances between the piston and the chamber are small, typically less than 60 µm. In order to measure this film thickness a fluorescent dye was added to the water passing through the meter, which was illuminated with UV light. Visible light images were captured with a digital camera and analysed to give a measure of the film thickness with an uncertainty of less than 7%. It is known that this method lacks precision unless careful calibration is undertaken. Methods to achieve this are discussed in the paper. The grey level values for a range of film thicknesses were calibrated in situ with six dye concentrations to select the most appropriate one for the range of liquid film thickness. Data obtained for the oscillating piston flowmeter demonstrate the value of the fluorescence technique. The method is useful, inexpensive and straightforward and can be extended to other applications where measurement of liquid film thickness is required.

Further characterization of the time transfer capabilities of precise point positioning (PPP): the Sliding Batch Procedure.

PubMed

Guyennon, Nicolas; Cerretto, Giancarlo; Tavella, Patrizia; Lahaye, François

2009-08-01

In recent years, many national timing laboratories have installed geodetic Global Positioning System receivers together with their traditional GPS/GLONASS Common View receivers and Two Way Satellite Time and Frequency Transfer equipment. Many of these geodetic receivers operate continuously within the International GNSS Service (IGS), and their data are regularly processed by IGS Analysis Centers. From its global network of over 350 stations and its Analysis Centers, the IGS generates precise combined GPS ephemeredes and station and satellite clock time series referred to the IGS Time Scale. A processing method called Precise Point Positioning (PPP) is in use in the geodetic community allowing precise recovery of GPS antenna position, clock phase, and atmospheric delays by taking advantage of these IGS precise products. Previous assessments, carried out at Istituto Nazionale di Ricerca Metrologica (INRiM; formerly IEN) with a PPP implementation developed at Natural Resources Canada (NRCan), showed PPP clock solutions have better stability over short/medium term than GPS CV and GPS P3 methods and significantly reduce the day-boundary discontinuities when used in multi-day continuous processing, allowing time-limited, campaign-style time-transfer experiments. This paper reports on follow-on work performed at INRiM and NRCan to further characterize and develop the PPP method for time transfer applications, using data from some of the National Metrology Institutes. We develop a processing procedure that takes advantage of the improved stability of the phase-connected multi-day PPP solutions while allowing the generation of continuous clock time series, more applicable to continuous operation/monitoring of timing equipment.

High-rate RTK and PPP multi-GNSS positioning for small-scale dynamic displacements monitoring

NASA Astrophysics Data System (ADS)

Paziewski, Jacek; Sieradzki, Rafał; Baryła, Radosław; Wielgosz, Pawel

2017-04-01

The monitoring of dynamic displacements and deformations of engineering structures such as buildings, towers and bridges is of great interest due to several practical and theoretical reasons. The most important is to provide information required for safe maintenance of the constructions. High temporal resolution and precision of GNSS observations predestine this technology to be applied to most demanding application in terms of accuracy, availability and reliability. GNSS technique supported by appropriate processing methodology may meet the specific demands and requirements of ground and structures monitoring. Thus, high-rate multi-GNSS signals may be used as reliable source of information on dynamic displacements of ground and engineering structures, also in real time applications. In this study we present initial results of application of precise relative GNSS positioning for detection of small scale (cm level) high temporal resolution dynamic displacements. Methodology and algorithms applied in self-developed software allowing for relative positioning using high-rate dual-frequency phase and pseudorange GPS+Galileo observations are also given. Additionally, an approach was also made to use the Precise Point Positioning technique to such application. In the experiment were used the observations obtained from high-rate (20 Hz) geodetic receivers. The dynamic displacements were simulated using specially constructed device moving GNSS antenna with dedicated amplitude and frequency. The obtained results indicate on possibility of detection of dynamic displacements of the GNSS antenna even at the level of few millimetres using both relative and Precise Point Positioning techniques after suitable signals processing.

A Self-Organizing Spatial Clustering Approach to Support Large-Scale Network RTK Systems.

PubMed

Shen, Lili; Guo, Jiming; Wang, Lei

2018-06-06

The network real-time kinematic (RTK) technique can provide centimeter-level real time positioning solutions and play a key role in geo-spatial infrastructure. With ever-increasing popularity, network RTK systems will face issues in the support of large numbers of concurrent users. In the past, high-precision positioning services were oriented towards professionals and only supported a few concurrent users. Currently, precise positioning provides a spatial foundation for artificial intelligence (AI), and countless smart devices (autonomous cars, unmanned aerial-vehicles (UAVs), robotic equipment, etc.) require precise positioning services. Therefore, the development of approaches to support large-scale network RTK systems is urgent. In this study, we proposed a self-organizing spatial clustering (SOSC) approach which automatically clusters online users to reduce the computational load on the network RTK system server side. The experimental results indicate that both the SOSC algorithm and the grid algorithm can reduce the computational load efficiently, while the SOSC algorithm gives a more elastic and adaptive clustering solution with different datasets. The SOSC algorithm determines the cluster number and the mean distance to cluster center (MDTCC) according to the data set, while the grid approaches are all predefined. The side-effects of clustering algorithms on the user side are analyzed with real global navigation satellite system (GNSS) data sets. The experimental results indicate that 10 km can be safely used as the cluster radius threshold for the SOSC algorithm without significantly reducing the positioning precision and reliability on the user side.

Sequential Linker Installation: Precise Placement of Functional Groups in Multivariate Metal-Organic Frameworks

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

Yuan, S; Lu, WG; Chen, YP

2015-03-11

A unique strategy, sequential linker installation (SLI), has been developed to construct multivariate MOFs with functional groups precisely positioned. PCN-700, a Zr-MOF with eight-connected Zr6O4(OH)(8)(H2O)(4) clusters, has been judiciously designed; the Zr-6 clusters in this MOF are arranged in such a fashion that, by replacement of terminal OH-/H2O ligands, subsequent insertion of linear dicarboxylate linkers is achieved. We demonstrate that linkers with distinct lengths and functionalities can be sequentially installed into PCN-700. Single-crystal to single-crystal transformation is realized so that the positions of the subsequently installed linkers are pinpointed via single-crystal X-ray diffraction analyses. This methodology provides a powerful toolmore » to construct multivariate MOFs with precisely positioned functionalities in the desired proximity, which would otherwise be difficult to achieve.« less

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

Sun, Rongyu; Zhao, Changyin; Zhang, Xiaoxiang, E-mail: cyzhao@pmo.ac.cn

The data reduction method for optical space debris observations has many similarities with the one adopted for surveying near-Earth objects; however, due to several specific issues, the image degradation is particularly critical, which makes it difficult to obtain precise astrometry. An automatic image reconstruction method was developed to improve the astrometry precision for space debris, based on the mathematical morphology operator. Variable structural elements along multiple directions are adopted for image transformation, and then all the resultant images are stacked to obtain a final result. To investigate its efficiency, trial observations are made with Global Positioning System satellites and themore » astrometry accuracy improvement is obtained by comparison with the reference positions. The results of our experiments indicate that the influence of degradation in astrometric CCD images is reduced, and the position accuracy of both objects and stellar stars is improved distinctly. Our technique will contribute significantly to optical data reduction and high-order precision astrometry for space debris.« less

Fixed-Wing Micro Aerial Vehicle for Accurate Corridor Mapping

NASA Astrophysics Data System (ADS)

Rehak, M.; Skaloud, J.

2015-08-01

In this study we present a Micro Aerial Vehicle (MAV) equipped with precise position and attitude sensors that together with a pre-calibrated camera enables accurate corridor mapping. The design of the platform is based on widely available model components to which we integrate an open-source autopilot, customized mass-market camera and navigation sensors. We adapt the concepts of system calibration from larger mapping platforms to MAV and evaluate them practically for their achievable accuracy. We present case studies for accurate mapping without ground control points: first for a block configuration, later for a narrow corridor. We evaluate the mapping accuracy with respect to checkpoints and digital terrain model. We show that while it is possible to achieve pixel (3-5 cm) mapping accuracy in both cases, precise aerial position control is sufficient for block configuration, the precise position and attitude control is required for corridor mapping.

Accuracy assessment of the Precise Point Positioning method applied for surveys and tracking moving objects in GIS environment

NASA Astrophysics Data System (ADS)

Ilieva, Tamara; Gekov, Svetoslav

2017-04-01

The Precise Point Positioning (PPP) method gives the users the opportunity to determine point locations using a single GNSS receiver. The accuracy of the determined by PPP point locations is better in comparison to the standard point positioning, due to the precise satellite orbit and clock corrections that are developed and maintained by the International GNSS Service (IGS). The aim of our current research is the accuracy assessment of the PPP method applied for surveys and tracking moving objects in GIS environment. The PPP data is collected by using preliminary developed by us software application that allows different sets of attribute data for the measurements and their accuracy to be used. The results from the PPP measurements are directly compared within the geospatial database to different other sets of terrestrial data - measurements obtained by total stations, real time kinematic and static GNSS.

Volcano monitoring using GPS: Developing data analysis strategies based on the June 2007 Kīlauea Volcano intrusion and eruption

USGS Publications Warehouse

Larson, Kristine M.; Poland, Michael; Miklius, Asta

2010-01-01

The global positioning system (GPS) is one of the most common techniques, and the current state of the art, used to monitor volcano deformation. In addition to slow (several centimeters per year) displacement rates, GPS can be used to study eruptions and intrusions that result in much larger (tens of centimeters over hours-days) displacements. It is challenging to resolve precise positions using GPS at subdaily time intervals because of error sources such as multipath and atmospheric refraction. In this paper, the impact of errors due to multipath and atmospheric refraction at subdaily periods is examined using data from the GPS network on Kīlauea Volcano, Hawai'i. Methods for filtering position estimates to enhance precision are both simulated and tested on data collected during the June 2007 intrusion and eruption. Comparisons with tiltmeter records show that GPS instruments can precisely recover the timing of the activity.

Real-Time PPP Based on the Coupling Estimation of Clock Bias and Orbit Error with Broadcast Ephemeris.

PubMed

Pan, Shuguo; Chen, Weirong; Jin, Xiaodong; Shi, Xiaofei; He, Fan

2015-07-22

Satellite orbit error and clock bias are the keys to precise point positioning (PPP). The traditional PPP algorithm requires precise satellite products based on worldwide permanent reference stations. Such an algorithm requires considerable work and hardly achieves real-time performance. However, real-time positioning service will be the dominant mode in the future. IGS is providing such an operational service (RTS) and there are also commercial systems like Trimble RTX in operation. On the basis of the regional Continuous Operational Reference System (CORS), a real-time PPP algorithm is proposed to apply the coupling estimation of clock bias and orbit error. The projection of orbit error onto the satellite-receiver range has the same effects on positioning accuracy with clock bias. Therefore, in satellite clock estimation, part of the orbit error can be absorbed by the clock bias and the effects of residual orbit error on positioning accuracy can be weakened by the evenly distributed satellite geometry. In consideration of the simple structure of pseudorange equations and the high precision of carrier-phase equations, the clock bias estimation method coupled with orbit error is also improved. Rovers obtain PPP results by receiving broadcast ephemeris and real-time satellite clock bias coupled with orbit error. By applying the proposed algorithm, the precise orbit products provided by GNSS analysis centers are rendered no longer necessary. On the basis of previous theoretical analysis, a real-time PPP system was developed. Some experiments were then designed to verify this algorithm. Experimental results show that the newly proposed approach performs better than the traditional PPP based on International GNSS Service (IGS) real-time products. The positioning accuracies of the rovers inside and outside the network are improved by 38.8% and 36.1%, respectively. The PPP convergence speeds are improved by up to 61.4% and 65.9%. The new approach can change the traditional PPP mode because of its advantages of independence, high positioning precision, and real-time performance. It could be an alternative solution for regional positioning service before global PPP service comes into operation.

Asynchronous RTK precise DGNSS positioning method for deriving a low-latency high-rate output

NASA Astrophysics Data System (ADS)

Liang, Zhang; Hanfeng, Lv; Dingjie, Wang; Yanqing, Hou; Jie, Wu

2015-07-01

Low-latency high-rate (1 Hz) precise real-time kinematic (RTK) can be applied in high-speed scenarios such as aircraft automatic landing, precise agriculture and intelligent vehicle. The classic synchronous RTK (SRTK) precise differential GNSS (DGNSS) positioning technology, however, is not able to obtain a low-latency high-rate output for the rover receiver because of long data link transmission time delays (DLTTD) from the reference receiver. To overcome the long DLTTD, this paper proposes an asynchronous real-time kinematic (ARTK) method using asynchronous observations from two receivers. The asynchronous observation model (AOM) is developed based on undifferenced carrier phase observation equations of the two receivers at different epochs with short baseline. The ephemeris error and atmosphere delay are the possible main error sources on positioning accuracy in this model, and they are analyzed theoretically. In a short DLTTD and during a period of quiet ionosphere activity, the main error sources decreasing positioning accuracy are satellite orbital errors: the "inverted ephemeris error" and the integration of satellite velocity error which increase linearly along with DLTTD. The cycle slip of asynchronous double-differencing carrier phase is detected by TurboEdit method and repaired by the additional ambiguity parameter method. The AOM can deal with synchronous observation model (SOM) and achieve precise positioning solution with synchronous observations as well, since the SOM is only a specific case of AOM. The proposed method not only can reduce the cost of data collection and transmission, but can also support the mobile phone network data link transfer mode for the data of the reference receiver. This method can avoid data synchronizing process besides ambiguity initialization step, which is very convenient for real-time navigation of vehicles. The static and kinematic experiment results show that this method achieves 20 Hz or even higher rate output in real time. The ARTK positioning accuracy is better and more robust than the combination of phase difference over time (PDOT) and SRTK method at a high rate. The ARTK positioning accuracy is equivalent to SRTK solution when the DLTTD is 0.5 s, and centimeter level accuracy can be achieved even when DLTTD is 15 s.

Real-Time PPP Based on the Coupling Estimation of Clock Bias and Orbit Error with Broadcast Ephemeris

PubMed Central

Pan, Shuguo; Chen, Weirong; Jin, Xiaodong; Shi, Xiaofei; He, Fan

2015-01-01

Satellite orbit error and clock bias are the keys to precise point positioning (PPP). The traditional PPP algorithm requires precise satellite products based on worldwide permanent reference stations. Such an algorithm requires considerable work and hardly achieves real-time performance. However, real-time positioning service will be the dominant mode in the future. IGS is providing such an operational service (RTS) and there are also commercial systems like Trimble RTX in operation. On the basis of the regional Continuous Operational Reference System (CORS), a real-time PPP algorithm is proposed to apply the coupling estimation of clock bias and orbit error. The projection of orbit error onto the satellite-receiver range has the same effects on positioning accuracy with clock bias. Therefore, in satellite clock estimation, part of the orbit error can be absorbed by the clock bias and the effects of residual orbit error on positioning accuracy can be weakened by the evenly distributed satellite geometry. In consideration of the simple structure of pseudorange equations and the high precision of carrier-phase equations, the clock bias estimation method coupled with orbit error is also improved. Rovers obtain PPP results by receiving broadcast ephemeris and real-time satellite clock bias coupled with orbit error. By applying the proposed algorithm, the precise orbit products provided by GNSS analysis centers are rendered no longer necessary. On the basis of previous theoretical analysis, a real-time PPP system was developed. Some experiments were then designed to verify this algorithm. Experimental results show that the newly proposed approach performs better than the traditional PPP based on International GNSS Service (IGS) real-time products. The positioning accuracies of the rovers inside and outside the network are improved by 38.8% and 36.1%, respectively. The PPP convergence speeds are improved by up to 61.4% and 65.9%. The new approach can change the traditional PPP mode because of its advantages of independence, high positioning precision, and real-time performance. It could be an alternative solution for regional positioning service before global PPP service comes into operation. PMID:26205276

An Inertial Sensor-Based Method for Estimating the Athlete's Relative Joint Center Positions and Center of Mass Kinematics in Alpine Ski Racing

PubMed Central

Fasel, Benedikt; Spörri, Jörg; Schütz, Pascal; Lorenzetti, Silvio; Aminian, Kamiar

2017-01-01

For the purpose of gaining a deeper understanding of the relationship between external training load and health in competitive alpine skiing, an accurate and precise estimation of the athlete's kinematics is an essential methodological prerequisite. This study proposes an inertial sensor-based method to estimate the athlete's relative joint center positions and center of mass (CoM) kinematics in alpine skiing. Eleven inertial sensors were fixed to the lower and upper limbs, trunk, and head. The relative positions of the ankle, knee, hip, shoulder, elbow, and wrist joint centers, as well as the athlete's CoM kinematics were validated against a marker-based optoelectronic motion capture system during indoor carpet skiing. For all joints centers analyzed, position accuracy (mean error) was below 110 mm and precision (error standard deviation) was below 30 mm. CoM position accuracy and precision were 25.7 and 6.7 mm, respectively. Both the accuracy and precision of the system to estimate the distance between the ankle of the outside leg and CoM (measure quantifying the skier's overall vertical motion) were found to be below 11 mm. Some poorer accuracy and precision values (below 77 mm) were observed for the athlete's fore-aft position (i.e., the projection of the outer ankle-CoM vector onto the line corresponding to the projection of ski's longitudinal axis on the snow surface). In addition, the system was found to be sensitive enough to distinguish between different types of turns (wide/narrow). Thus, the method proposed in this paper may also provide a useful, pervasive way to monitor and control adverse external loading patterns that occur during regular on-snow training. Moreover, as demonstrated earlier, such an approach might have a certain potential to quantify competition time, movement repetitions and/or the accelerations acting on the different segments of the human body. However, prior to getting feasible for applications in daily training, future studies should primarily focus on a simplification of the sensor setup, as well as a fusion with global navigation satellite systems (i.e., the estimation of the absolute joint and CoM positions). PMID:29163196

The GFZ real-time GNSS precise positioning service system and its adaption for COMPASS

NASA Astrophysics Data System (ADS)

Li, Xingxing; Ge, Maorong; Zhang, Hongping; Nischan, Thomas; Wickert, Jens

2013-03-01

Motivated by the IGS real-time Pilot Project, GFZ has been developing its own real-time precise positioning service for various applications. An operational system at GFZ is now broadcasting real-time orbits, clocks, global ionospheric model, uncalibrated phase delays and regional atmospheric corrections for standard PPP, PPP with ambiguity fixing, single-frequency PPP and regional augmented PPP. To avoid developing various algorithms for different applications, we proposed a uniform algorithm and implemented it into our real-time software. In the new processing scheme, we employed un-differenced raw observations with atmospheric delays as parameters, which are properly constrained by real-time derived global ionospheric model or regional atmospheric corrections and by the empirical characteristics of the atmospheric delay variation in time and space. The positioning performance in terms of convergence time and ambiguity fixing depends mainly on the quality of the received atmospheric information and the spatial and temporal constraints. The un-differenced raw observation model can not only integrate PPP and NRTK into a seamless positioning service, but also syncretize these two techniques into a unique model and algorithm. Furthermore, it is suitable for both dual-frequency and sing-frequency receivers. Based on the real-time data streams from IGS, EUREF and SAPOS reference networks, we can provide services of global precise point positioning (PPP) with 5-10 cm accuracy, PPP with ambiguity-fixing of 2-5 cm accuracy, PPP using single-frequency receiver with accuracy of better than 50 cm and PPP with regional augmentation for instantaneous ambiguity resolution of 1-3 cm accuracy. We adapted the system for current COMPASS to provide PPP service. COMPASS observations from a regional network of nine stations are used for precise orbit determination and clock estimation in simulated real-time mode, the orbit and clock products are applied for real-time precise point positioning. The simulated real-time PPP service confirms that real-time positioning services of accuracy at dm-level and even cm-level is achievable with COMPASS only.

An Inertial Sensor-Based Method for Estimating the Athlete's Relative Joint Center Positions and Center of Mass Kinematics in Alpine Ski Racing.

PubMed

Fasel, Benedikt; Spörri, Jörg; Schütz, Pascal; Lorenzetti, Silvio; Aminian, Kamiar

2017-01-01

For the purpose of gaining a deeper understanding of the relationship between external training load and health in competitive alpine skiing, an accurate and precise estimation of the athlete's kinematics is an essential methodological prerequisite. This study proposes an inertial sensor-based method to estimate the athlete's relative joint center positions and center of mass (CoM) kinematics in alpine skiing. Eleven inertial sensors were fixed to the lower and upper limbs, trunk, and head. The relative positions of the ankle, knee, hip, shoulder, elbow, and wrist joint centers, as well as the athlete's CoM kinematics were validated against a marker-based optoelectronic motion capture system during indoor carpet skiing. For all joints centers analyzed, position accuracy (mean error) was below 110 mm and precision (error standard deviation) was below 30 mm. CoM position accuracy and precision were 25.7 and 6.7 mm, respectively. Both the accuracy and precision of the system to estimate the distance between the ankle of the outside leg and CoM (measure quantifying the skier's overall vertical motion) were found to be below 11 mm. Some poorer accuracy and precision values (below 77 mm) were observed for the athlete's fore-aft position (i.e., the projection of the outer ankle-CoM vector onto the line corresponding to the projection of ski's longitudinal axis on the snow surface). In addition, the system was found to be sensitive enough to distinguish between different types of turns (wide/narrow). Thus, the method proposed in this paper may also provide a useful, pervasive way to monitor and control adverse external loading patterns that occur during regular on-snow training. Moreover, as demonstrated earlier, such an approach might have a certain potential to quantify competition time, movement repetitions and/or the accelerations acting on the different segments of the human body. However, prior to getting feasible for applications in daily training, future studies should primarily focus on a simplification of the sensor setup, as well as a fusion with global navigation satellite systems (i.e., the estimation of the absolute joint and CoM positions).

Electron Microscopic Visualization of Protein Assemblies on Flattened DNA Origami.

PubMed

Mallik, Leena; Dhakal, Soma; Nichols, Joseph; Mahoney, Jacob; Dosey, Anne M; Jiang, Shuoxing; Sunahara, Roger K; Skiniotis, Georgios; Walter, Nils G

2015-07-28

DNA provides an ideal substrate for the engineering of versatile nanostructures due to its reliable Watson-Crick base pairing and well-characterized conformation. One of the most promising applications of DNA nanostructures arises from the site-directed spatial arrangement with nanometer precision of guest components such as proteins, metal nanoparticles, and small molecules. Two-dimensional DNA origami architectures, in particular, offer a simple design, high yield of assembly, and large surface area for use as a nanoplatform. However, such single-layer DNA origami were recently found to be structurally polymorphous due to their high flexibility, leading to the development of conformationally restrained multilayered origami that lack some of the advantages of the single-layer designs. Here we monitored single-layer DNA origami by transmission electron microscopy (EM) and discovered that their conformational heterogeneity is dramatically reduced in the presence of a low concentration of dimethyl sulfoxide, allowing for an efficient flattening onto the carbon support of an EM grid. We further demonstrated that streptavidin and a biotinylated target protein (cocaine esterase, CocE) can be captured at predesignated sites on these flattened origami while maintaining their functional integrity. Our demonstration that protein assemblies can be constructed with high spatial precision (within ∼2 nm of their predicted position on the platforms) by using strategically flattened single-layer origami paves the way for exploiting well-defined guest molecule assemblies for biochemistry and nanotechnology applications.

Small animal radiotherapy research platforms

NASA Astrophysics Data System (ADS)

Verhaegen, Frank; Granton, Patrick; Tryggestad, Erik

2011-06-01

Advances in conformal radiation therapy and advancements in pre-clinical radiotherapy research have recently stimulated the development of precise micro-irradiators for small animals such as mice and rats. These devices are often kilovolt x-ray radiation sources combined with high-resolution CT imaging equipment for image guidance, as the latter allows precise and accurate beam positioning. This is similar to modern human radiotherapy practice. These devices are considered a major step forward compared to the current standard of animal experimentation in cancer radiobiology research. The availability of this novel equipment enables a wide variety of pre-clinical experiments on the synergy of radiation with other therapies, complex radiation schemes, sub-target boost studies, hypofractionated radiotherapy, contrast-enhanced radiotherapy and studies of relative biological effectiveness, to name just a few examples. In this review we discuss the required irradiation and imaging capabilities of small animal radiation research platforms. We describe the need for improved small animal radiotherapy research and highlight pioneering efforts, some of which led recently to commercially available prototypes. From this, it will be clear that much further development is still needed, on both the irradiation side and imaging side. We discuss at length the need for improved treatment planning tools for small animal platforms, and the current lack of a standard therein. Finally, we mention some recent experimental work using the early animal radiation research platforms, and the potential they offer for advancing radiobiology research.

Chicano Alternative Education.

ERIC Educational Resources Information Center

Galicia, H. Homero; Almaguer, Clementina

Alternative schooling is challenging some basic notions of curriculum, operation, and structure of traditional schools; it is not challenging the basic concept of schooling. Chicano alternative education, an elusive concept, lacks a precise definition. Chicano alternative schools reflect a vast diversity in structure, focus, and goals. The Chicano…

Precision Medicine for Heart Failure with Preserved Ejection Fraction: An Overview.

PubMed

Shah, Sanjiv J

2017-06-01

There are few proven therapies for heart failure with preserved ejection fraction (HFpEF). The lack of therapies, along with increased recognition of the disorder and its underlying pathophysiology, has led to the acknowledgement that HFpEF is heterogeneous and is not likely to respond to a one-size-fits-all approach. Thus, HFpEF is a prime candidate to benefit from a precision medicine approach. For this reason, we have assembled a compendium of papers on the topic of precision medicine in HFpEF in the Journal of Cardiovascular Translational Research. These papers cover a variety of topics relevant to precision medicine in HFpEF, including automated identification of HFpEF patients; machine learning, novel molecular approaches, genomics, and deep phenotyping of HFpEF; and clinical trial designs that can be used to advance precision medicine in HFpEF. In this introductory article, we provide an overview of precision medicine in HFpEF with the hope that the work described here and in the other papers in this special theme issue will stimulate investigators and clinicians to advance a more targeted approach to HFpEF classification and treatment.

Precision Medicine for Heart Failure with Preserved Ejection Fraction: An Overview

PubMed Central

Shah, Sanjiv J.

2017-01-01

There are few proven therapies for heart failure with preserved ejection fraction (HFpEF). The lack of therapies, along with increased recognition of the disorder and its underlying pathophysiology, has led to the acknowledgement that HFpEF is heterogeneous and is not likely to respond to a one-size-fits-all approach. Thus, HFpEF is a prime candidate to benefit from a precision medicine approach. For this reason, we have assembled a compendium of papers on the topic of precision medicine in HFpEF in the Journal of Cardiovascular Translational Research. These papers cover a variety of topics relevant to precision medicine in HFpEF, including automated identification of HFpEF patients; machine learning, novel molecular approaches, genomics, and deep phenotyping of HFpEF; and clinical trial designs that can be used to advance precision medicine in HFpEF. In this introductory article, we provide an overview of precision medicine in HFpEF with the hope that the work described here and in the other papers in this special theme issue will stimulate investigators and clinicians to advance a more targeted approach to HFpEF classification and treatment. PMID:28585183

The Impact of Estimating High-Resolution Tropospheric Gradients on Multi-GNSS Precise Positioning

PubMed Central

Zhou, Feng; Li, Xingxing; Li, Weiwei; Chen, Wen; Dong, Danan; Wickert, Jens; Schuh, Harald

2017-01-01

Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only in positioning, navigation, and timing (PNT), but also in remote sensing of the atmosphere and ionosphere. Both precise positioning and the derivation of atmospheric parameters can benefit from multi-GNSS observations. In this contribution, extensive evaluations are conducted with multi-GNSS datasets collected from 134 globally-distributed ground stations of the International GNSS Service (IGS) Multi-GNSS Experiment (MGEX) network in July 2016. The datasets are processed in six different constellation combinations, i.e., GPS-, GLONASS-, BDS-only, GPS + GLONASS, GPS + BDS, and GPS + GLONASS + BDS + Galileo precise point positioning (PPP). Tropospheric gradients are estimated with eight different temporal resolutions, from 1 h to 24 h, to investigate the impact of estimating high-resolution gradients on position estimates. The standard deviation (STD) is used as an indicator of positioning repeatability. The results show that estimating tropospheric gradients with high temporal resolution can achieve better positioning performance than the traditional strategy in which tropospheric gradients are estimated on a daily basis. Moreover, the impact of estimating tropospheric gradients with different temporal resolutions at various elevation cutoff angles (from 3° to 20°) is investigated. It can be observed that with increasing elevation cutoff angles, the improvement in positioning repeatability is decreased. PMID:28368346

The Impact of Estimating High-Resolution Tropospheric Gradients on Multi-GNSS Precise Positioning.

PubMed

Zhou, Feng; Li, Xingxing; Li, Weiwei; Chen, Wen; Dong, Danan; Wickert, Jens; Schuh, Harald

2017-04-03

Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only in positioning, navigation, and timing (PNT), but also in remote sensing of the atmosphere and ionosphere. Both precise positioning and the derivation of atmospheric parameters can benefit from multi-GNSS observations. In this contribution, extensive evaluations are conducted with multi-GNSS datasets collected from 134 globally-distributed ground stations of the International GNSS Service (IGS) Multi-GNSS Experiment (MGEX) network in July 2016. The datasets are processed in six different constellation combinations, i.e., GPS-, GLONASS-, BDS-only, GPS + GLONASS, GPS + BDS, and GPS + GLONASS + BDS + Galileo precise point positioning (PPP). Tropospheric gradients are estimated with eight different temporal resolutions, from 1 h to 24 h, to investigate the impact of estimating high-resolution gradients on position estimates. The standard deviation (STD) is used as an indicator of positioning repeatability. The results show that estimating tropospheric gradients with high temporal resolution can achieve better positioning performance than the traditional strategy in which tropospheric gradients are estimated on a daily basis. Moreover, the impact of estimating tropospheric gradients with different temporal resolutions at various elevation cutoff angles (from 3° to 20°) is investigated. It can be observed that with increasing elevation cutoff angles, the improvement in positioning repeatability is decreased.

GPS vertical axis performance enhancement for helicopter precision landing approach

NASA Technical Reports Server (NTRS)

Denaro, Robert P.; Beser, Jacques

1986-01-01

Several areas were investigated for improving vertical accuracy for a rotorcraft using the differential Global Positioning System (GPS) during a landing approach. Continuous deltaranging was studied and the potential improvement achieved by estimating acceleration was studied by comparing the performance on a constant acceleration turn and a rough landing profile of several filters: a position-velocity (PV) filter, a position-velocity-constant acceleration (PVAC) filter, and a position-velocity-turning acceleration (PVAT) filter. In overall statistics, the PVAC filter was found to be most efficient with the more complex PVAT performing equally well. Vertical performance was not significantly different among the filters. Satellite selection algorithms based on vertical errors only (vertical dilution of precision or VDOP) and even-weighted cross-track and vertical errors (XVDOP) were tested. The inclusion of an altimeter was studied by modifying the PVAC filter to include a baro bias estimate. Improved vertical accuracy during degraded DOP conditions resulted. Flight test results for raw differential results excluding filter effects indicated that the differential performance significantly improved overall navigation accuracy. A landing glidepath steering algorithm was devised which exploits the flexibility of GPS in determining precise relative position. A method for propagating the steering command over the GPS update interval was implemented.

Comparison of computer assisted surgery with conventional technique for treatment of abaxial distal phalanx fractures in horses: an in vitro study.

PubMed

Rossol, Melanie; Gygax, Diego; Andritzky-Waas, Juliane; Zheng, Guoyan; Lischer, Christoph J; Zhang, Xuan; Auer, Joerg A

2008-01-01

To (1) evaluate and compare computer-assisted surgery (CAS) with conventional screw insertion (conventional osteosynthesis [COS]) for treatment of equine abaxial distal phalanx fractures; (2) compare planned screw position with actual postoperative position; and (3) determine preferred screw insertion direction. Experimental study. Cadaveric equine limbs (n=32). In 8 specimens each, a 4.5 mm cortex bone screw was inserted in lag fashion in dorsopalmar (plantar) direction using CAS or COS. In 2 other groups of 8, the screws were inserted in opposite direction. Precision of CAS was determined by comparison of planned and actual screw position. Preferred screw direction was also assessed for CAS and COS. In 4 of 6 direct comparisons, screw positioning was significantly better with CAS. Results of precision analysis for screw position were similar to studies published in human medicine. None of evaluated criteria identified a preferred direction for screw insertion. For abaxial fractures of the distal phalanx, superior precision in screw position is achieved with CAS technique compared with COS technique. Abaxial fractures of the distal phalanx lend themselves to computer-assisted implantation of 1 screw in a dorsopalmar (plantar) direction. Because of the complex anatomic relationships, and our results, we discourage use of COS technique for repair of this fracture type.

Validation of a standardized mapping system of the hip joint for radial MRA sequencing.

PubMed

Klenke, Frank M; Hoffmann, Daniel B; Cross, Brian J; Siebenrock, Klaus A

2015-03-01

Intraarticular gadolinium-enhanced magnetic resonance arthrography (MRA) is commonly applied to characterize morphological disorders of the hip. However, the reproducibility of retrieving anatomic landmarks on MRA scans and their correlation with intraarticular pathologies is unknown. A precise mapping system for the exact localization of hip pathomorphologies with radial MRA sequences is lacking. Therefore, the purpose of the study was the establishment and validation of a reproducible mapping system for radial sequences of hip MRA. Sixty-nine consecutive intraarticular gadolinium-enhanced hip MRAs were evaluated. Radial sequencing consisted of 14 cuts orientated along the axis of the femoral neck. Three orthopedic surgeons read the radial sequences independently. Each MRI was read twice with a minimum interval of 7 days from the first reading. The intra- and inter-observer reliability of the mapping procedure was determined. A clockwise system for hip MRA was established. The teardrop figure served to determine the 6 o'clock position of the acetabulum; the center of the greater trochanter served to determine the 12 o'clock position of the femoral head-neck junction. The intra- and inter-observer ICCs to retrieve the correct 6/12 o'clock positions were 0.906-0.996 and 0.978-0.988, respectively. The established mapping system for radial sequences of hip joint MRA is reproducible and easy to perform.

Intelligent clutch control with incremental encoder to improve wear issues of an intercept pendulum in real time

NASA Astrophysics Data System (ADS)

Jalba, C. K.; Diekmann, R.; Epple, S.

2017-01-01

A pendulum impact tester is a technical device which is used to perform plasticity characterizations of metallic materials. Results are calculated based on fracture behavior under pendulum impact loadings according to DIN 50115, DIN 51222/EN 10045. The material is held at the two ends and gets struck in the middle. A mechanical Problem occurs when testing materials with a very high impact toughness. These specimen often do not break when hit by the pendulum. To return the pendulum to its initial position, the operator presses a service button. After a delay of approximately 2 seconds a clutch is activated which connects the arm of the pendulum with an electric motor to return it back upright in start position. At the moment of clutch activation, the pendulum can still swing or bounce with any speed in any direction at any different position. Due to the lack of synchronization between pendulum speed and constant engine speed, the clutch suffers heavy wear of friction. This disadvantage results in considerable service and repair costs for the customer. As a solution to this problem this article presents a customized technical device to significantly increase the lifetime of the clutch. It was accomplished by a precisely controlled activation of the clutch at a point of time when pendulum and motor are at synchronized speed and direction using incremental encoders.

Relative receiver autonomous integrity monitoring for future GNSS-based aircraft navigation

NASA Astrophysics Data System (ADS)

Gratton, Livio Rafael

The Global Positioning System (GPS) has enabled reliable, safe, and practical aircraft positioning for en-route and non-precision phases of flight for more than a decade. Intense research is currently devoted to extending the use of Global Navigation Satellite Systems (GNSS), including GPS, to precision approach and landing operations. In this context, this work is focused on the development, analysis, and verification of the concept of Relative Receiver Autonomous Integrity Monitoring (RRAIM) and its potential applications to precision approach navigation. RRAIM fault detection algorithms are developed, and associated mathematical bounds on position error are derived. These are investigated as possible solutions to some current key challenges in precision approach navigation, discussed below. Augmentation systems serving continent-size areas (like the Wide Area Augmentation System or WAAS) allow certain precision approach operations within the covered region. More and better satellites, with dual frequency capabilities, are expected to be in orbit in the mid-term future, which will potentially allow WAAS-like capabilities worldwide with a sparse ground station network. Two main challenges in achieving this goal are (1) ensuring that navigation fault detection functions are fast enough to alert worldwide users of hazardously misleading information, and (2) minimizing situations in which navigation is unavailable because the user's local satellite geometry is insufficient for safe position estimation. Local augmentation systems (implemented at individual airports, like the Local Area Augmentation System or LAAS) have the potential to allow precision approach and landing operations by providing precise corrections to user-satellite range measurements. An exception to these capabilities arises during ionospheric storms (caused by solar activity), when hazardous situations can exist with residual range errors several orders of magnitudes higher than nominal. Until dual frequency civil GPS signals are available, the ability to provide integrity during ionospheric storms, without excessive loss of availability is a major challenge. For all users, with or without augmentation, some situations cause short duration losses of satellites in view. Two examples are aircraft banking during turns and ionospheric scintillation. The loss of range signals can translate into gaps in good satellite geometry, and the resulting challenge is to ensure navigation continuity by bridging these gaps, while simultaneously maintaining high integrity. It is shown that the RRAIM methods developed in this research can be applied to mitigate each of these obstacles to safe and reliable precision aircraft navigation.

Sequential dynamics in visual short-term memory.

PubMed

Kool, Wouter; Conway, Andrew R A; Turk-Browne, Nicholas B

2014-10-01

Visual short-term memory (VSTM) is thought to help bridge across changes in visual input, and yet many studies of VSTM employ static displays. Here we investigate how VSTM copes with sequential input. In particular, we characterize the temporal dynamics of several different components of VSTM performance, including: storage probability, precision, variability in precision, guessing, and swapping. We used a variant of the continuous-report VSTM task developed for static displays, quantifying the contribution of each component with statistical likelihood estimation, as a function of serial position and set size. In Experiments 1 and 2, storage probability did not vary by serial position for small set sizes, but showed a small primacy effect and a robust recency effect for larger set sizes; precision did not vary by serial position or set size. In Experiment 3, the recency effect was shown to reflect an increased likelihood of swapping out items from earlier serial positions and swapping in later items, rather than an increased rate of guessing for earlier items. Indeed, a model that incorporated responding to non-targets provided a better fit to these data than alternative models that did not allow for swapping or that tried to account for variable precision. These findings suggest that VSTM is updated in a first-in-first-out manner, and they bring VSTM research into closer alignment with classical working memory research that focuses on sequential behavior and interference effects.

Mapped Landmark Algorithm for Precision Landing

NASA Technical Reports Server (NTRS)

Johnson, Andrew; Ansar, Adnan; Matthies, Larry

2007-01-01

A report discusses a computer vision algorithm for position estimation to enable precision landing during planetary descent. The Descent Image Motion Estimation System for the Mars Exploration Rovers has been used as a starting point for creating code for precision, terrain-relative navigation during planetary landing. The algorithm is designed to be general because it handles images taken at different scales and resolutions relative to the map, and can produce mapped landmark matches for any planetary terrain of sufficient texture. These matches provide a measurement of horizontal position relative to a known landing site specified on the surface map. Multiple mapped landmarks generated per image allow for automatic detection and elimination of bad matches. Attitude and position can be generated from each image; this image-based attitude measurement can be used by the onboard navigation filter to improve the attitude estimate, which will improve the position estimates. The algorithm uses normalized correlation of grayscale images, producing precise, sub-pixel images. The algorithm has been broken into two sub-algorithms: (1) FFT Map Matching (see figure), which matches a single large template by correlation in the frequency domain, and (2) Mapped Landmark Refinement, which matches many small templates by correlation in the spatial domain. Each relies on feature selection, the homography transform, and 3D image correlation. The algorithm is implemented in C++ and is rated at Technology Readiness Level (TRL) 4.

Sequential dynamics in visual short-term memory

PubMed Central

Conway, Andrew R. A.; Turk-Browne, Nicholas B.

2014-01-01

Visual short-term memory (VSTM) is thought to help bridge across changes in visual input, and yet many studies of VSTM employ static displays. Here we investigate how VSTM copes with sequential input. In particular, we characterize the temporal dynamics of several different components of VSTM performance, including: storage probability, precision, variability in precision, guessing, and swapping. We used a variant of the continuous-report VSTM task developed for static displays, quantifying the contribution of each component with statistical likelihood estimation, as a function of serial position and set size. In Experiments 1 and 2, storage probability did not vary by serial position for small set sizes, but showed a small primacy effect and a robust recency effect for larger set sizes; precision did not vary by serial position or set size. In Experiment 3, the recency effect was shown to reflect an increased likelihood of swapping out items from earlier serial positions and swapping in later items, rather than an increased rate of guessing for earlier items. Indeed, a model that incorporated responding to non-targets provided a better fit to these data than alternative models that did not allow for swapping or that tried to account for variable precision. These findings suggest that VSTM is updated in a first-in-first-out manner, and they bring VSTM research into closer alignment with classical working memory research that focuses on sequential behavior and interference effects. PMID:25228092

Precision Time Protocol-Based Trilateration for Planetary Navigation

NASA Technical Reports Server (NTRS)

Murdock, Ron

2015-01-01

Progeny Systems Corporation has developed a high-fidelity, field-scalable, non-Global Positioning System (GPS) navigation system that offers precision localization over communications channels. The system is bidirectional, providing position information to both base and mobile units. It is the first-ever wireless use of the Institute of Electrical and Electronics Engineers (IEEE) Precision Time Protocol (PTP) in a bidirectional trilateration navigation system. The innovation provides a precise and reliable navigation capability to support traverse-path planning systems and other mapping applications, and it establishes a core infrastructure for long-term lunar and planetary occupation. Mature technologies are integrated to provide navigation capability and to support data and voice communications on the same network. On Earth, the innovation is particularly well suited for use in unmanned aerial vehicles (UAVs), as it offers a non-GPS precision navigation and location service for use in GPS-denied environments. Its bidirectional capability provides real-time location data to the UAV operator and to the UAV. This approach optimizes assisted GPS techniques and can be used to determine the presence of GPS degradation, spoofing, or jamming.

High-precision two-dimensional atom localization from four-wave mixing in a double-Λ four-level atomic system

NASA Astrophysics Data System (ADS)

Shui, Tao; Yang, Wen-Xing; Chen, Ai-Xi; Liu, Shaopeng; Li, Ling; Zhu, Zhonghu

2018-03-01

We propose a scheme for high-precision two-dimensional (2D) atom localization via the four-wave mixing (FWM) in a four-level double-Λ atomic system. Due to the position-dependent atom-field interaction, the 2D position information of the atoms can be directly determined by the measurement of the normalized light intensity of output FWM-generated field. We further show that, when the position-dependent generated FWM field has become sufficiently intense, efficient back-coupling to the FWM generating state becomes important. This back-coupling pathway leads to competitive multiphoton destructive interference of the FWM generating state by three supplied and one internally generated fields. We find that the precision of 2D atom localization can be improved significantly by the multiphoton destructive interference and depends sensitively on the frequency detunings and the pump field intensity. Interestingly enough, we show that adjusting the frequency detunings and the pump field intensity can modify significantly the FWM efficiency, and consequently lead to a redistribution of the atoms. As a result, the atom can be localized in one of four quadrants with holding the precision of atom localization.

Irrigation timing and volume affects growth of container grown maples

USDA-ARS?s Scientific Manuscript database

Container nursery production requires large inputs of water and nutrients but frequently irrigation inputs exceed plant demand and lack application precision or are not applied at optimal times for plant production. The results from this research can assist producers in developing irrigation manage...

Communicating the Library as a Learning Environment

ERIC Educational Resources Information Center

Nitecki, Danuta A.; Simpson, Katherine

2016-01-01

Lack of commonly used vocabulary for informal learning environments hinders precise communication concerning what is observed, assessed, and understood about the relationship between space and learning. This study empirically extends taxonomies of terms and phrases that describe such relationships through content analysis of descriptions of…

An approach for real-time fast point positioning of the BeiDou Navigation Satellite System using augmentation information

NASA Astrophysics Data System (ADS)

Tu, Rui; Zhang, Rui; Zhang, Pengfei; Liu, Jinhai; Lu, Xiaochun

2018-07-01

This study proposes an approach to facilitate real-time fast point positioning of the BeiDou Navigation Satellite System (BDS) based on regional augmentation information. We term this as the precise positioning based on augmentation information (BPP) approach. The coordinates of the reference stations were highly constrained to extract the augmentation information, which contained not only the satellite orbit clock error correlated with the satellite running state, but also included the atmosphere error and unmodeled error, which are correlated with the spatial and temporal states. Based on these mixed augmentation corrections, a precise point positioning (PPP) model could be used for the coordinates estimation of the user stations, and the float ambiguity could be easily fixed for the single-difference between satellites. Thus, this technique provided a quick and high-precision positioning service. Three different datasets with small, medium, and large baselines (0.6 km, 30 km and 136 km) were used to validate the feasibility and effectiveness of the proposed BPP method. The validations showed that using the BPP model, 1–2 cm positioning service can be provided in a 100 km wide area after just 2 s of initialization. Thus, as the proposed approach not only capitalized on both PPP and RTK but also provided consistent application, it can be used for area augmentation positioning.

Kinematic-PPP using Single/Dual Frequency Observations from (GPS, GLONASS and GPS/GLONASS) Constellations for Hydrography

NASA Astrophysics Data System (ADS)

Farah, Ashraf

2018-03-01

Global Positioning System (GPS) technology is ideally suited for inshore and offshore positioning because of its high accuracy and the short observation time required for a position fix. Precise point positioning (PPP) is a technique used for position computation with a high accuracy using a single GNSS receiver. It relies on highly accurate satellite position and clock data that can be acquired from different sources such as the International GNSS Service (IGS). PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of observations among other factors. PPP offers comparable accuracy to differential GPS with safe in cost and time. For many years, PPP users depended on GPS (American system) which considered the solely reliable system. GLONASS's contribution in PPP techniques was limited due to fail in maintaining full constellation. Yet, GLONASS limited observations could be integrated into GPS-based PPP to improve availability and precision. As GLONASS reached its full constellation early 2013, there is a wide interest in PPP systems based on GLONASS only and independent of GPS. This paper investigates the performance of kinematic PPP solution for the hydrographic applications in the Nile river (Aswan, Egypt) based on GPS, GLONASS and GPS/GLONASS constellations. The study investigates also the effect of using two different observation types; single-frequency and dual frequency observations from the tested constellations.

Precision displacement reference system

DOEpatents

Bieg, Lothar F.; Dubois, Robert R.; Strother, Jerry D.

2000-02-22

A precision displacement reference system is described, which enables real time accountability over the applied displacement feedback system to precision machine tools, positioning mechanisms, motion devices, and related operations. As independent measurements of tool location is taken by a displacement feedback system, a rotating reference disk compares feedback counts with performed motion. These measurements are compared to characterize and analyze real time mechanical and control performance during operation.

The synaptic ribbon is critical for sound encoding at high rates and with temporal precision

PubMed Central

Chakrabarti, Rituparna; Picher, Maria Magdalena; Neef, Jakob; Jung, SangYong; Gültas, Mehmet; Maxeiner, Stephan

2018-01-01

We studied the role of the synaptic ribbon for sound encoding at the synapses between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) in mice lacking RIBEYE (RBEKO/KO). Electron and immunofluorescence microscopy revealed a lack of synaptic ribbons and an assembly of several small active zones (AZs) at each synaptic contact. Spontaneous and sound-evoked firing rates of SGNs and their compound action potential were reduced, indicating impaired transmission at ribbonless IHC-SGN synapses. The temporal precision of sound encoding was impaired and the recovery of SGN-firing from adaptation indicated slowed synaptic vesicle (SV) replenishment. Activation of Ca2+-channels was shifted to more depolarized potentials and exocytosis was reduced for weak depolarizations. Presynaptic Ca2+-signals showed a broader spread, compatible with the altered Ca2+-channel clustering observed by super-resolution immunofluorescence microscopy. We postulate that RIBEYE disruption is partially compensated by multi-AZ organization. The remaining synaptic deficit indicates ribbon function in SV-replenishment and Ca2+-channel regulation. PMID:29328020

Precision Agriculture. Reaping the Benefits of Technological Growth. Resources in Technology.

ERIC Educational Resources Information Center

Hadley, Joel F.

1998-01-01

Technological innovations have revolutionized farming. Using precision farming techniques, farmers get an accurate picture of a field's attributes, such as soil properties, yield rates, and crop characteristics through the use of Differential Global Positioning Satellite hardware. (JOW)

Pelvis and lower limb anatomical landmark calibration precision and its propagation to bone geometry and joint angles.

PubMed

della Croce, U; Cappozzo, A; Kerrigan, D C

1999-03-01

Human movement analysis using stereophotogrammetry is based on the reconstruction of the instantaneous laboratory position of selected bony anatomical landmarks (AL). For this purpose, knowledge of an AL's position in relevant bone-embedded frames is required. Because ALs are not points but relatively large and curved areas, their identification by palpation or other means is subject to both intra- and inter-examiner variability. In addition, the local position of ALs, as reconstructed using an ad hoc experimental procedure (AL calibration), is affected by photogrammetric errors. The intra- and inter-examiner precision with which local positions of pelvis and lower limb palpable bony ALs can be identified and reconstructed were experimentally assessed. Six examiners and two subjects participated in the study. Intra- and inter-examiner precision (RMS distance from the mean position) resulted in the range 6-21 mm and 13-25 mm, respectively. Propagation of the imprecision of ALs to the orientation of bone-embedded anatomical frames and to hip, knee and ankle joint angles was assessed. Results showed that this imprecision may cause distortion in joint angle against time functions to the extent that information relative to angular movements in the range of 10 degrees or lower may be concealed. Bone geometry parameters estimated using the same data showed that the relevant precision does not allow for reliable bone geometry description. These findings, together with those relative to skin movement artefacts reported elsewhere, assist the human movement analyst's consciousness of the possible limitations involved in 3D movement analysis using stereophotogrammetry and call for improvements of the relevant experimental protocols.

Breakthrough in current-in-plane tunneling measurement precision by application of multi-variable fitting algorithm.

PubMed

Cagliani, Alberto; Østerberg, Frederik W; Hansen, Ole; Shiv, Lior; Nielsen, Peter F; Petersen, Dirch H

2017-09-01

We present a breakthrough in micro-four-point probe (M4PP) metrology to substantially improve precision of transmission line (transfer length) type measurements by application of advanced electrode position correction. In particular, we demonstrate this methodology for the M4PP current-in-plane tunneling (CIPT) technique. The CIPT method has been a crucial tool in the development of magnetic tunnel junction (MTJ) stacks suitable for magnetic random-access memories for more than a decade. On two MTJ stacks, the measurement precision of resistance-area product and tunneling magnetoresistance was improved by up to a factor of 3.5 and the measurement reproducibility by up to a factor of 17, thanks to our improved position correction technique.

Spot-Welding Gun With Adjustable Pneumatic Spring

NASA Technical Reports Server (NTRS)

Burley, Richard K.

1990-01-01

Proposed spot-welding gun equipped with pneumatic spring, which could be bellows or piston and cylinder, exerts force independent of position along stroke. Applies accurate controlled force to joint welded, without precise positioning at critical position within stroke.

BDS/GPS Dual Systems Positioning Based on the Modified SR-UKF Algorithm

PubMed Central

Kong, JaeHyok; Mao, Xuchu; Li, Shaoyuan

2016-01-01

The Global Navigation Satellite System can provide all-day three-dimensional position and speed information. Currently, only using the single navigation system cannot satisfy the requirements of the system’s reliability and integrity. In order to improve the reliability and stability of the satellite navigation system, the positioning method by BDS and GPS navigation system is presented, the measurement model and the state model are described. Furthermore, the modified square-root Unscented Kalman Filter (SR-UKF) algorithm is employed in BDS and GPS conditions, and analysis of single system/multi-system positioning has been carried out, respectively. The experimental results are compared with the traditional estimation results, which show that the proposed method can perform highly-precise positioning. Especially when the number of satellites is not adequate enough, the proposed method combine BDS and GPS systems to achieve a higher positioning precision. PMID:27153068

Development and Positioning Accuracy Assessment of Single-Frequency Precise Point Positioning Algorithms by Combining GPS Code-Pseudorange Measurements with Real-Time SSR Corrections

PubMed Central

Kim, Miso; Park, Kwan-Dong

2017-01-01

We have developed a suite of real-time precise point positioning programs to process GPS pseudorange observables, and validated their performance through static and kinematic positioning tests. To correct inaccurate broadcast orbits and clocks, and account for signal delays occurring from the ionosphere and troposphere, we applied State Space Representation (SSR) error corrections provided by the Seoul Broadcasting System (SBS) in South Korea. Site displacements due to solid earth tide loading are also considered for the purpose of improving the positioning accuracy, particularly in the height direction. When the developed algorithm was tested under static positioning, Kalman-filtered solutions produced a root-mean-square error (RMSE) of 0.32 and 0.40 m in the horizontal and vertical directions, respectively. For the moving platform, the RMSE was found to be 0.53 and 0.69 m in the horizontal and vertical directions. PMID:28598403

Specific Oral Communication Skills Desired in New Accountancy Graduates

ERIC Educational Resources Information Center

Gray, F. Elizabeth

2010-01-01

International research findings and anecdotal evidence alike suggest that new accountancy graduates often begin their careers with inadequate oral communication skills. However, there is a lack of well-grounded empirical data concerning precisely what accountancy employers mean by "oral communication" and what specific skills they value…

Binge Drinking in Young Adults: Data, Definitions and Determinants

ERIC Educational Resources Information Center

Courtney, Kelly E.; Polich, John

2009-01-01

Binge drinking is an increasingly important topic in alcohol research, but the field lacks empirical cohesion and definitional precision. The present review summarizes findings and viewpoints from the scientific binge-drinking literature. Epidemiological studies quantify the seriousness of alcohol-related problems arising from binge drinking, with…

World Class Schools: An Evolving Concept.

ERIC Educational Resources Information Center

Jenkins, John M., Ed.; And Others

The concept of "world class," often used in reference to education, lacks a precise, universal definition. This book presents case studies of exemplary schools. The foreword by Fenwick W. English presents a developmental concept of world-class education, in which fair and comparable standards, with sufficient room for sociocultural…

Precision resection of intestine using ultrashort laser pulses

NASA Astrophysics Data System (ADS)

Beck, Rainer J.; Gora, Wojciech S.; Jayne, David; Hand, Duncan P.; Shephard, Jonathan D.

2016-03-01

Endoscopic resection of early colorectal neoplasms typically employs electrocautery tools, which lack precision and run the risk of full thickness thermal injury to the bowel wall with subsequent perforation. We present a means of endoluminal colonic ablation using picosecond laser pulses as a potential alternative to mitigate these limitations. High intensity ultrashort laser pulses enable nonlinear absorption processes, plasma generation, and as a consequence a predominantly non-thermal ablation regimen. Robust process parameters for the laser resection are demonstrated using fresh ex vivo pig intestine samples. Square cavities with comparable thickness to early colorectal neoplasms are removed for a wavelength of 1030 nm and 515 nm using a picosecond laser system. The corresponding histology sections exhibit in both cases only minimal collateral damage to the surrounding tissue. The ablation depth can be controlled precisely by means of the pulse energy. Overall, the application of ultrafast lasers for the resection of intestine enables significantly improved precision and reduced thermal damage to the surrounding tissue compared to conventional electrocautery.

Precision medicine for nurses: 101.

PubMed

Lemoine, Colleen

2014-05-01

To introduce the key concepts and terms associated with precision medicine and support understanding of future developments in the field by providing an overview and history of precision medicine, related ethical considerations, and nursing implications. Current nursing, medical and basic science literature. Rapid progress in understanding the oncogenic drivers associated with cancer is leading to a shift toward precision medicine, where treatment is based on targeting specific genetic and epigenetic alterations associated with a particular cancer. Nurses will need to embrace the paradigm shift to precision medicine, expend the effort necessary to learn the essential terminology, concepts and principles, and work collaboratively with physician colleagues to best position our patients to maximize the potential that precision medicine can offer. Copyright © 2014 Elsevier Inc. All rights reserved.

Development of low-altitude remote sensing systems for crop production management

USDA-ARS?s Scientific Manuscript database

Precision agriculture accounts for within-field variability for targeted treatment rather than uniform treatment of an entire field. Precision agriculture is built on agricultural mechanization and state-of-the-art technologies of geographical information systems (GIS), global positioning systems (G...

Heavy duty precision leveling jacks expedite setup time on horizontal boring mill

NASA Technical Reports Server (NTRS)

Dellenbaugh, W.; Jones, C.

1966-01-01

Leveling jack is a precise alignment tool which expedites the setup of components or assemblies up to 2500 pounds on horizontal boring mills. This tool eliminates the necessity of wedges and blocks to shim the components to proper position.

Broadband laser ranging precision and accuracy experiments with PDV benchmarking

NASA Astrophysics Data System (ADS)

Catenacci, Jared; Daykin, Ed; Howard, Marylesa; Lalone, Brandon; Miller, Kirk

2017-06-01

Broadband laser ranging (BLR) is a developmental diagnostic designed to measure the precise position of surfaces and particle clouds moving at velocities of several kilometers per second. Recent single stage gas gun experiments were conducted to quantify the precision and accuracy possible with a typical BLR system. For these experiments, the position of a mirrored projectile is measured relative to the location of a stationary optical flat (uncoated window) mounted within the gun catch tank. Projectile velocity is constrained to one-dimensional motion within the gun barrel. A collimating probe is aligned to be orthogonal to both the target window and the mirrored impactor surface. The probe is used to simultaneously measure the position and velocity with a BLR and conventional Photonic Doppler Velocimetry (PDV) system. Since there is a negligible lateral component to the target velocity, coupled with strong signal returns from a mirrored surface, integrating the PDV measurement provides a high fidelity distance measurement reference to which the BLR measurement may be compared.

Precision and accuracy in smFRET based structural studies—A benchmark study of the Fast-Nano-Positioning System

NASA Astrophysics Data System (ADS)

Nagy, Julia; Eilert, Tobias; Michaelis, Jens

2018-03-01

Modern hybrid structural analysis methods have opened new possibilities to analyze and resolve flexible protein complexes where conventional crystallographic methods have reached their limits. Here, the Fast-Nano-Positioning System (Fast-NPS), a Bayesian parameter estimation-based analysis method and software, is an interesting method since it allows for the localization of unknown fluorescent dye molecules attached to macromolecular complexes based on single-molecule Förster resonance energy transfer (smFRET) measurements. However, the precision, accuracy, and reliability of structural models derived from results based on such complex calculation schemes are oftentimes difficult to evaluate. Therefore, we present two proof-of-principle benchmark studies where we use smFRET data to localize supposedly unknown positions on a DNA as well as on a protein-nucleic acid complex. Since we use complexes where structural information is available, we can compare Fast-NPS localization to the existing structural data. In particular, we compare different dye models and discuss how both accuracy and precision can be optimized.

A modular and compact portable mini-endstation for high-precision, high-speed fixed target serial crystallography at FEL and synchrotron sources

DOE PAGES

Sherrell, Darren A.; Foster, Andrew J.; Hudson, Lee; ...

2015-01-01

The design and implementation of a compact and portable sample alignment system suitable for use at both synchrotron and free-electron laser (FEL) sources and its performance are described. The system provides the ability to quickly and reliably deliver large numbers of samples using the minimum amount of sample possible, through positioning of fixed target arrays into the X-ray beam. The combination of high-precision stages, high-quality sample viewing, a fast controller and a software layer overcome many of the challenges associated with sample alignment. A straightforward interface that minimizes setup and sample changeover time as well as simplifying communication with themore » stages during the experiment is also described, together with an intuitive naming convention for defining, tracking and locating sample positions. Lastly, the setup allows the precise delivery of samples in predefined locations to a specific position in space and time, reliably and simply.« less

Real-time Kinematic Positioning of INS Tightly Aided Multi-GNSS Ionospheric Constrained PPP

PubMed Central

Gao, Zhouzheng; Shen, Wenbin; Zhang, Hongping; Niu, Xiaoji; Ge, Maorong

2016-01-01

Real-time Precise Point Positioning (PPP) technique is being widely applied for providing precise positioning services with the significant improvement on satellite precise products accuracy. With the rapid development of the multi-constellation Global Navigation Satellite Systems (multi-GNSS), currently, about 80 navigation satellites are operational in orbit. Obviously, PPP performance is dramatically improved with all satellites compared to that of GPS-only PPP. However, the performance of PPP could be evidently affected by unexpected and unavoidable severe observing environments, especially in the dynamic applications. Consequently, we apply Inertial Navigation System (INS) to the Ionospheric-Constrained (IC) PPP to overcome such drawbacks. The INS tightly aided multi-GNSS IC-PPP model can make full use of GNSS and INS observations to improve the PPP performance in terms of accuracy, availability, continuity, and convergence speed. Then, a set of airborne data is analyzed to evaluate and validate the improvement of multi-GNSS and INS on the performance of IC-PPP. PMID:27470270

Real-time Kinematic Positioning of INS Tightly Aided Multi-GNSS Ionospheric Constrained PPP.

PubMed

Gao, Zhouzheng; Shen, Wenbin; Zhang, Hongping; Niu, Xiaoji; Ge, Maorong

2016-07-29

Real-time Precise Point Positioning (PPP) technique is being widely applied for providing precise positioning services with the significant improvement on satellite precise products accuracy. With the rapid development of the multi-constellation Global Navigation Satellite Systems (multi-GNSS), currently, about 80 navigation satellites are operational in orbit. Obviously, PPP performance is dramatically improved with all satellites compared to that of GPS-only PPP. However, the performance of PPP could be evidently affected by unexpected and unavoidable severe observing environments, especially in the dynamic applications. Consequently, we apply Inertial Navigation System (INS) to the Ionospheric-Constrained (IC) PPP to overcome such drawbacks. The INS tightly aided multi-GNSS IC-PPP model can make full use of GNSS and INS observations to improve the PPP performance in terms of accuracy, availability, continuity, and convergence speed. Then, a set of airborne data is analyzed to evaluate and validate the improvement of multi-GNSS and INS on the performance of IC-PPP.

Precise orbit determination for NASA's earth observing system using GPS (Global Positioning System)

NASA Technical Reports Server (NTRS)

Williams, B. G.

1988-01-01

An application of a precision orbit determination technique for NASA's Earth Observing System (EOS) using the Global Positioning System (GPS) is described. This technique allows the geometric information from measurements of GPS carrier phase and P-code pseudo-range to be exploited while minimizing requirements for precision dynamical modeling. The method combines geometric and dynamic information to determine the spacecraft trajectory; the weight on the dynamic information is controlled by adjusting fictitious spacecraft accelerations in three dimensions which are treated as first order exponentially time correlated stochastic processes. By varying the time correlation and uncertainty of the stochastic accelerations, the technique can range from purely geometric to purely dynamic. Performance estimates for this technique as applied to the orbit geometry planned for the EOS platforms indicate that decimeter accuracies for EOS orbit position may be obtainable. The sensitivity of the predicted orbit uncertainties to model errors for station locations, nongravitational platform accelerations, and Earth gravity is also presented.

IL-17s adopt a cystine knot fold: structure and activity of a novel cytokine, IL-17F, and implications for receptor binding

PubMed Central

Hymowitz, Sarah G.; Filvaroff, Ellen H.; Yin, JianPing; Lee, James; Cai, Liping; Risser, Philip; Maruoka, Miko; Mao, Weiguang; Foster, Jessica; Kelley, Robert F.; Pan, Guohua; Gurney, Austin L.; de Vos, Abraham M.; Starovasnik, Melissa A.

2001-01-01

The proinflammatory cytokine interleukin 17 (IL-17) is the founding member of a family of secreted proteins that elicit potent cellular responses. We report a novel human IL-17 homolog, IL-17F, and show that it is expressed by activated T cells, can stimulate production of other cytokines such as IL-6, IL-8 and granulocyte colony-stimulating factor, and can regulate cartilage matrix turnover. Unexpectedly, the crystal structure of IL-17F reveals that IL-17 family members adopt a monomer fold typical of cystine knot growth factors, despite lacking the disulfide responsible for defining the canonical ‘knot’ structure. IL-17F dimerizes in a parallel manner like neurotrophins, and features an unusually large cavity on its surface. Remarkably, this cavity is located in precisely the same position where nerve growth factor binds its high affinity receptor, TrkA, suggesting further parallels between IL-17s and neurotrophins with respect to receptor recognition. PMID:11574464

A flowchart for managing sexually transmitted infections among Nigerian adolescent females.

PubMed Central

Obunge, O. K.; Brabin, L.; Dollimore, N.; Kemp, J.; Ikokwu-Wonodi, C.; Babatunde, S.; White, S.; Briggs, N. D.; Hart, C. A.

2001-01-01

OBJECTIVE: To devise a flowchart suitable for assessing risk of trichomoniasis, chlamydia and gonorrhoea in an adolescent population, not all of whom will be sexually experienced or currently in a relationship. METHODS: The data used to derive the flowchart were generated from cross-sectional microbiological surveys of girls aged 14-19 years in Port Harcourt, Nigeria. The flowchart screened on the basis of: (i) sexual experience; (ii) recent sexual activity; (iii) a positive urine leukocyte esterase (LE) test; and (iv) among LE negatives, a history of malodorous/pruritic discharge. FINDINGS: Using this flowchart, we found that 26.2% of all adolescents screened would receive treatment for cervicitis and vaginitis. Chlamydial, gonococcal, and trichomonal infections were correctly diagnosed in 37.5%, 66.7%, and 50% of the cases, respectively. CONCLUSION: Although the flowchart is more suitable for an adolescent population than the vaginal discharge algorithm used in syndromic management protocols, it still lacks precision and needs adapting to local settings. PMID:11357208

Quantitation of Fine Displacement in Echography

NASA Astrophysics Data System (ADS)

Masuda, Kohji; Ishihara, Ken; Yoshii, Ken; Furukawa, Toshiyuki; Kumagai, Sadatoshi; Maeda, Hajime; Kodama, Shinzo

1993-05-01

A High-speed Digital Subtraction Echography was developed to visualize the fine displacement of human internal organs. This method indicates differences in position through time series images of high-frame-rate echography. Fine displacement less than ultrasonic wavelength can be observed. This method, however, lacks the ability to quantitatively measure displacement length. The subtraction between two successive images was affected by displacement direction in spite of the displacement length being the same. To solve this problem, convolution of an echogram with Gaussian distribution was used. To express displacement length as brightness quantitatively, normalization using a brightness gradient was applied. The quantitation algorithm was applied to successive B-mode images. Compared to the simply subtracted images, quantitated images express more precisely the motion of organs. Expansion of the carotid artery and fine motion of ventricular walls can be visualized more easily. Displacement length can be quantitated with wavelength. Under more static conditions, this system quantitates displacement length that is much less than wavelength.

A study of the comparative anatomy of the brain of domestic ruminants using magnetic resonance imaging.

PubMed

Schmidt, M J; Langen, N; Klumpp, S; Nasirimanesh, F; Shirvanchi, P; Ondreka, N; Kramer, M

2012-01-01

Although magnetic resonance imaging has been used to examine the brain of domestic ruminants, detailed information relating the precise anatomical features in these species is lacking. In this study the brain structures of calves (Bos taurus domesticus), sheep (Ovis aries), goats (Capra hircus) and a mesaticephalic dog (Canis lupis familiaris) were examined using T2-weighed Turbo Spin Echo sequences; three-dimensional models based on high-resolution gradient echo scans were used to identify brain sulci and gyri in two-dimensional images. The ruminant brains examined were similar in structure and organisation to those of other mammals but particular features included the deep depression of the insula and the pronounced gyri of the cortices, the dominant position of the visual (optic nerve, optic chiasm and rostral colliculus) and olfactory (olfactory bulb, olfactory tracts and piriform lobe) systems, and the relatively large size of the diencephalon. Copyright © 2010 Elsevier Ltd. All rights reserved.

Fluorescent nanodiamonds enable quantitative tracking of human mesenchymal stem cells in miniature pigs

NASA Astrophysics Data System (ADS)

Su, Long-Jyun; Wu, Meng-Shiue; Hui, Yuen Yung; Chang, Be-Ming; Pan, Lei; Hsu, Pei-Chen; Chen, Yit-Tsong; Ho, Hong-Nerng; Huang, Yen-Hua; Ling, Thai-Yen; Hsu, Hsao-Hsun; Chang, Huan-Cheng

2017-03-01

Cell therapy is a promising strategy for the treatment of human diseases. While the first use of cells for therapeutic purposes can be traced to the 19th century, there has been a lack of general and reliable methods to study the biodistribution and associated pharmacokinetics of transplanted cells in various animal models for preclinical evaluation. Here, we present a new platform using albumin-conjugated fluorescent nanodiamonds (FNDs) as biocompatible and photostable labels for quantitative tracking of human placenta choriodecidual membrane-derived mesenchymal stem cells (pcMSCs) in miniature pigs by magnetic modulation. With this background-free detection technique and time-gated fluorescence imaging, we have been able to precisely determine the numbers as well as positions of the transplanted FND-labeled pcMSCs in organs and tissues of the miniature pigs after intravenous administration. The method is applicable to single-cell imaging and quantitative tracking of human stem/progenitor cells in rodents and other animal models as well.

The case for MR-compatible robotics: a review of the state of the art.

PubMed

Elhawary, Haytham; Tse, Zion Tsz Ho; Hamed, Abbi; Rea, Marc; Davies, Brian L; Lamperth, Michael U

2008-06-01

The numerous imaging capabilities of magnetic resonance imaging (MRI) coupled with its lack of ionizing radiation has made it a desirable modality for real-time guidance of interventional procedures. The combination of these abilities with the advantages granted by robotic systems to perform accurate and precise positioning of tools has driven the recent development of MR-compatible interventional and assistive devices. The challenges in this field are presented, including the selection of suitable materials, actuators and sensors in the intense magnetic fields of the MR environment. Only a small number of developed systems have made it to the clinical level (only two have become commercial ventures), showing that the field has not yet reached maturity. A brief overview of the current state of the art is given, along with a description of the main opportunities, possibilities and challenges that the future will bring to this exciting and promising field. Copyright (c) 2008 John Wiley & Sons, Ltd.

Subcortical Control of Precision Grip after Human Spinal Cord Injury

PubMed Central

Bunday, Karen L.; Tazoe, Toshiki; Rothwell, John C.

2014-01-01

The motor cortex and the corticospinal system contribute to the control of a precision grip between the thumb and index finger. The involvement of subcortical pathways during human precision grip remains unclear. Using noninvasive cortical and cervicomedullary stimulation, we examined motor evoked potentials (MEPs) and the activity in intracortical and subcortical pathways targeting an intrinsic hand muscle when grasping a small (6 mm) cylinder between the thumb and index finger and during index finger abduction in uninjured humans and in patients with subcortical damage due to incomplete cervical spinal cord injury (SCI). We demonstrate that cortical and cervicomedullary MEP size was reduced during precision grip compared with index finger abduction in uninjured humans, but was unchanged in SCI patients. Regardless of whether cortical and cervicomedullary stimulation was used, suppression of the MEP was only evident 1–3 ms after its onset. Long-term (∼5 years) use of the GABAb receptor agonist baclofen by SCI patients reduced MEP size during precision grip to similar levels as uninjured humans. Index finger sensory function correlated with MEP size during precision grip in SCI patients. Intracortical inhibition decreased during precision grip and spinal motoneuron excitability remained unchanged in all groups. Our results demonstrate that the control of precision grip in humans involves premotoneuronal subcortical mechanisms, likely disynaptic or polysynaptic spinal pathways that are lacking after SCI and restored by long-term use of baclofen. We propose that spinal GABAb-ergic interneuronal circuits, which are sensitive to baclofen, are part of the subcortical premotoneuronal network shaping corticospinal output during human precision grip. PMID:24849366

Study on the position accuracy of a mechanical alignment system

NASA Astrophysics Data System (ADS)

Cai, Yimin

In this thesis, we investigated the precision level and established the baseline achieved by a mechanical alignment system using datums and reference surfaces. The factors which affect the accuracy of mechanical alignment system were studied and methodology was developed to suppress these factors so as to reach its full potential precision. In order to characterize the mechanical alignment system quantitatively, a new optical position monitoring system by using quadrant detectors has been developed in this thesis, it can monitor multi-dimensional degrees of mechanical workpieces in real time with high precision. We studied the noise factors inside the system and optimized the optical system. Based on the fact that one of the major limiting noise factors is the shifting of the laser beam, a noise cancellation technique has been developed successfully to suppress this noise, the feasibility of an ultra high resolution (<20 A) for displacement monitoring has been demonstrated. Using the optical position monitoring system, repeatability experiment of the mechanical alignment system has been conducted on different kinds of samples including steel, aluminum, glass and plastics with the same size 100mm x 130mm. The alignment accuracy was studied quantitatively rather than qualitatively before. In a controlled environment, the alignment precision can be improved 5 folds by securing the datum without other means of help. The alignment accuracy of an aluminum workpiece having reference surface by milling is about 3 times better than by shearing. Also we have found that sample material can have fairly significant effect on the alignment precision of the system. Contamination trapped between the datum and reference surfaces in mechanical alignment system can cause errors of registration or reduce the level of manufacturing precision. In the thesis, artificial and natural dust particles were used to simulate the real situations and their effects on system precision have been investigated. In this experiment, we discovered two effective cleaning processes.

Research on the impact factors of GRACE precise orbit determination by dynamic method

NASA Astrophysics Data System (ADS)

Guo, Nan-nan; Zhou, Xu-hua; Li, Kai; Wu, Bin

2018-07-01

With the successful use of GPS-only-based POD (precise orbit determination), more and more satellites carry onboard GPS receivers to support their orbit accuracy requirements. It provides continuous GPS observations in high precision, and becomes an indispensable way to obtain the orbit of LEO satellites. Precise orbit determination of LEO satellites plays an important role for the application of LEO satellites. Numerous factors should be considered in the POD processing. In this paper, several factors that impact precise orbit determination are analyzed, namely the satellite altitude, the time-variable earth's gravity field, the GPS satellite clock error and accelerometer observation. The GRACE satellites provide ideal platform to study the performance of factors for precise orbit determination using zero-difference GPS data. These factors are quantitatively analyzed on affecting the accuracy of dynamic orbit using GRACE observations from 2005 to 2011 by SHORDE software. The study indicates that: (1) with the altitude of the GRACE satellite is lowered from 480 km to 460 km in seven years, the 3D (three-dimension) position accuracy of GRACE satellite orbit is about 3˜4 cm based on long spans data; (2) the accelerometer data improves the 3D position accuracy of GRACE in about 1 cm; (3) the accuracy of zero-difference dynamic orbit is about 6 cm with the GPS satellite clock error products in 5 min sampling interval and can be raised to 4 cm, if the GPS satellite clock error products with 30 s sampling interval can be adopted. (4) the time-variable part of earth gravity field model improves the 3D position accuracy of GRACE in about 0.5˜1.5 cm. Based on this study, we quantitatively analyze the factors that affect precise orbit determination of LEO satellites. This study plays an important role to improve the accuracy of LEO satellites orbit determination.

Composite x-ray image assembly for large-field digital mammography with one- and two-dimensional positioning of a focal plane array

NASA Technical Reports Server (NTRS)

Halama, G.; McAdoo, J.; Liu, H.

1998-01-01

To demonstrate the feasibility of a novel large-field digital mammography technique, a 1024 x 1024 pixel Loral charge-coupled device (CCD) focal plane array (FPA) was positioned in a mammographic field with one- and two-dimensional scan sequences to obtain 950 x 1800 pixel and 3600 x 3600 pixel composite images, respectively. These experiments verify that precise positioning of FPAs produced seamless composites and that the CCD mosaic concept has potential for high-resolution, large-field imaging. The proposed CCD mosaic concept resembles a checkerboard pattern with spacing left between the CCDs for the driver and readout electronics. To obtain a complete x-ray image, the mosaic must be repositioned four times, with an x-ray exposure at each position. To reduce the patient dose, a lead shield with appropriately patterned holes is placed between the x-ray source and the patient. The high-precision motorized translation stages and the fiber-coupled-scintillating-screen-CCD sensor assembly were placed in the position usually occupied by the film cassette. Because of the high mechanical precision, seamless composites were constructed from the subimages. This paper discusses the positioning, image alignment procedure, and composite image results. The paper only addresses the formation of a seamless composite image from subimages and will not consider the effects of the lead shield, multiple CCDs, or the speed of motion.

Precise orbit determination based on raw GPS measurements

NASA Astrophysics Data System (ADS)

Zehentner, Norbert; Mayer-Gürr, Torsten

2016-03-01

Precise orbit determination is an essential part of the most scientific satellite missions. Highly accurate knowledge of the satellite position is used to geolocate measurements of the onboard sensors. For applications in the field of gravity field research, the position itself can be used as observation. In this context, kinematic orbits of low earth orbiters (LEO) are widely used, because they do not include a priori information about the gravity field. The limiting factor for the achievable accuracy of the gravity field through LEO positions is the orbit accuracy. We make use of raw global positioning system (GPS) observations to estimate the kinematic satellite positions. The method is based on the principles of precise point positioning. Systematic influences are reduced by modeling and correcting for all known error sources. Remaining effects such as the ionospheric influence on the signal propagation are either unknown or not known to a sufficient level of accuracy. These effects are modeled as unknown parameters in the estimation process. The redundancy in the adjustment is reduced; however, an improvement in orbit accuracy leads to a better gravity field estimation. This paper describes our orbit determination approach and its mathematical background. Some examples of real data applications highlight the feasibility of the orbit determination method based on raw GPS measurements. Its suitability for gravity field estimation is presented in a second step.

Development of a methodology for the assessment of sea level rise impacts on Florida's transportation modes and infrastructure : [summary].

DOT National Transportation Integrated Search

2012-01-01

In Florida, low elevations can make transportation infrastructure in coastal and low-lying areas potentially vulnerable to sea level rise (SLR). Becuase global SLR forecasts lack precision at local or regional scales, SLR forecasts or scenarios for p...

Accountability: Its Implications for Provincial and State Governments.

ERIC Educational Resources Information Center

Kolesar, H.

This paper examines the implications of the accountability concept for provincial or State authorities. Accountability is defined as a concomitant of an agreement between two parties. The author suggests that, in education, agreements between parties have lacked preciseness and clarity, making it extremely difficult to assess performance and to…

Validation studies of Karl Fisher reference method for moisture in cotton

USDA-ARS?s Scientific Manuscript database

With current international standard oven drying (SOD) techniques lacking precision and accuracy statements, a new standard reference method is needed. Volumetric Karl Fischer Titration (KFT) is a widely used measure of moisture content. The method is used in many ASTM methods, 14 NIST SRMs, and te...

Measurement of semiochemical release rates with a dedicated environmental control system

Treesearch

Heping Zhu; Harold W. Thistle; Christopher M. Ranger; Hongping Zhou; Brian L. Strom

2015-01-01

Insect semiochemical dispensers are commonly deployed under variable environmental conditions over a specified period. Predictions of their longevity are hampered by a lack of methods to accurately monitor and predict how primary variables affect semiochemical release rate. A system was constructed to precisely determine semiochemical release rates under...

Interest in Science: A RIASEC-Based Analysis of Students' Interests

ERIC Educational Resources Information Center

Dierks, Pay O.; Höffler, Tim N.; Blankenburg, Janet S.; Peters, Heide; Parchmann, Ilka

2016-01-01

Considering the reported lack of interest in the STEM-domain and the consequential difficulties in recruiting talented and interested young academics, the development of effective enrichment measures is indispensable. This requires a precise picture of students' interests. The paper presents an approach to characterize interest profiles in…

Clarifying the Consensus Definition of Validity

ERIC Educational Resources Information Center

Newton, Paul E.

2012-01-01

The 1999 "Standards for Educational and Psychological Testing" defines validity as the degree to which evidence and theory support the interpretations of test scores entailed by proposed uses of tests. Although quite explicit, there are ways in which this definition lacks precision, consistency, and clarity. The history of validity has taught us…

People Who Study Higher Education

ERIC Educational Resources Information Center

Harland, Tony

2009-01-01

The study of higher education can seem extraordinarily complex because what counts as knowledge is contestable and the higher education research community is, like Hemingway's Paris, a moveable feast. A lack of epistemological precision and field uncertainty is partly due to the fact that those who study higher education tend to work in higher…

USE OF AGRICULTURAL PESTICIDES AND PROSTATE CANCER RISK IN THE AGRICULTURAL HEALTH STUDY COHORT

EPA Science Inventory

The role of specific agricultural chemicals in relation to prostate cancer risk has not been firmly established due to the lack of precise exposure data. We examined the relationship between 45 common agricultural pesticides and prostate cancer incidence in a prospective cohor...

Phenotypic, ultra-structural and functional characterization of bovine peripheral blood dendritic cell subsets

USDA-ARS?s Scientific Manuscript database

Dendritic cells (DC) are multifunctional cells that bridge the gap between innate and adaptive immune systems. In bovine, significant information is lacking on the precise identity and role of peripheral blood DC subsets. In this study, we identify and characterize bovine peripheral blood DC subsets...

Tightly coupled integration of ionosphere-constrained precise point positioning and inertial navigation systems.

PubMed

Gao, Zhouzheng; Zhang, Hongping; Ge, Maorong; Niu, Xiaoji; Shen, Wenbin; Wickert, Jens; Schuh, Harald

2015-03-10

The continuity and reliability of precise GNSS positioning can be seriously limited by severe user observation environments. The Inertial Navigation System (INS) can overcome such drawbacks, but its performance is clearly restricted by INS sensor errors over time. Accordingly, the tightly coupled integration of GPS and INS can overcome the disadvantages of each individual system and together form a new navigation system with a higher accuracy, reliability and availability. Recently, ionosphere-constrained (IC) precise point positioning (PPP) utilizing raw GPS observations was proven able to improve both the convergence and positioning accuracy of the conventional PPP using ionosphere-free combined observations (LC-PPP). In this paper, a new mode of tightly coupled integration, in which the IC-PPP instead of LC-PPP is employed, is implemented to further improve the performance of the coupled system. We present the detailed mathematical model and the related algorithm of the new integration of IC-PPP and INS. To evaluate the performance of the new tightly coupled integration, data of both airborne and vehicle experiments with a geodetic GPS receiver and tactical grade inertial measurement unit are processed and the results are analyzed. The statistics show that the new approach can further improve the positioning accuracy compared with both IC-PPP and the tightly coupled integration of the conventional PPP and INS.

Synchronized motion control and precision positioning compensation of a 3-DOFs macro-micro parallel manipulator fully actuated by piezoelectric actuators

NASA Astrophysics Data System (ADS)

Zhang, Quan; Li, Chaodong; Zhang, Jiantao; Zhang, Xu

2017-11-01

The macro-micro combined approach, as an effective way to realize trans-scale nano-precision positioning with multi-dimensions and high velocity, plays a significant role in integrated circuit manufacturing field. A 3-degree-of-freedoms (3-DOFs) macro-micro manipulator is designed and analyzed to compromise the conflictions among the large stroke, high precision and multi-DOFs. The macro manipulator is a 3-Prismatic-Revolute-Revolute (3-PRR) structure parallel manipulator which is driven by three linear ultrasonic motors. The dynamic model and the cross-coupling error based synchronized motion controller of the 3-PRR parallel manipulator are theoretical analyzed and experimental tested. To further improve the positioning accuracy, a 3-DOFs monolithic compliant manipulator actuated by three piezoelectric stack actuators is designed. Then a multilayer BP neural network based inverse kinematic model identifier is developed to perform the positioning control. Finally, by forming the macro-micro structure, the dual stage manipulator successfully achieved the positioning task from the point (2 mm, 2 mm, 0 rad) back to the original point (0 mm, 0 mm, 0 rad) with the translation errors in X and Y directions less than ±50 nm and the rotation error around Z axis less than ±1 μrad, respectively.

The measurement of Earth rotation on a deformable Earth

NASA Technical Reports Server (NTRS)

Cannon, W. H.

1980-01-01

Until recently, the methods of geodetic positioning on the Earth were limited to a precision of roughly one part in 10 to the 6th power. At this level of precision, the Earth can be regarded as a rigid body since the largest departure of the Earth from rigidity is manifested in the strains of the Earth tides which are of the order of one part in 10 to the 7th power. Long baseline interferometry is expected to routinely provide global positioning to a precision of one part in 10 to the 8th power or better. At this level of precision, all parts of the Earth's surface must be regarded as being, at least potentially, in continual motion relative to the geocenter as a result of a variety of geophysical effects. The general implications of this phenomenon for the theory of the Earth's rotation is discussed. Particular attention is given to the question of the measurement of the 'Earth's rotation vector' on a deformable Earth.

Space Technology 7 Disturbance Reduction System - precision control flight Validation

NASA Technical Reports Server (NTRS)

Carmain, Andrew J.; Dunn, Charles; Folkner, William; Hruby, Vlad; Spence, Doug; O'Donnell, James; Markley, Landis; Maghami, Peiman; Hsu, Oscar; Demmons, N.;

Practical controller design for ultra-precision positioning of stages with a pneumatic artificial muscle actuator

NASA Astrophysics Data System (ADS)

Tang, T. F.; Chong, S. H.

2017-06-01

This paper presents a practical controller design method for ultra-precision positioning of pneumatic artificial muscle actuator stages. Pneumatic artificial muscle (PAM) actuators are safe to use and have numerous advantages which have brought these actuators to wide applications. However, PAM exhibits strong non-linear characteristics, and these limitations lead to low controllability and limit its application. In practice, the non-linear characteristics of PAM mechanism are difficult to be precisely modeled, and time consuming to model them accurately. The purpose of the present study is to clarify a practical controller design method that emphasizes a simple design procedure that does not acquire plants parameters modeling, and yet is able to demonstrate ultra-precision positioning performance for a PAM driven stage. The practical control approach adopts continuous motion nominal characteristic trajectory following (CM NCTF) control as the feedback controller. The constructed PAM driven stage is in low damping characteristic and causes severe residual vibration that deteriorates motion accuracy of the system. Therefore, the idea to increase the damping characteristic by having an acceleration feedback compensation to the plant has been proposed. The effectiveness of the proposed controller was verified experimentally and compared with a classical PI controller in point-to-point motion. The experiment results proved that the CM NCTF controller demonstrates better positioning performance in smaller motion error than the PI controller. Overall, the CM NCTF controller has successfully to reduce motion error to 3µm, which is 88.7% smaller than the PI controller.

Merging Galaxy Clusters: A Case Study of ZwCl 2341.1+0000 and the Development of a New Forward Modeled Lensing Technique

NASA Astrophysics Data System (ADS)

Benson, Bryant Joseph

Context: Galaxy clusters are the most massive gravitationally bound structures in the universe and are formed through the process of hierarchical clustering, in which smaller systems undergo a series of mergers to form ever larger clusters. Because of the masses involved, mergers between these giants provide a unique laboratory for observing many interesting astrophysical processes. These merging systems also act as large dark matter colliders, because the dark matter halos of the clusters involved pass through each other during of the merger. This offers us a means to observe if dark matter-dark matter collisions result in momentum exchange beyond what occurs from gravity alone. Such observations can help us to unravel some of the mysteries behind dark matter, such as does it interact with itself through mechanisms beyond gravity, and how strong are those interactions. Answers to questions like these are what will eventually allow us to discover what dark matter really is. However, the extremely long time scales for these mergers (˜several billion years) make each observation a single snapshot in the long merger history, and we must infer many of the details necessary for understanding the full merger process. Furthermore, current weak lensing analyses lack the precision required to detect a signal from self-interacting dark matter. Uncertain weak lensing mass and position estimates also yield large uncertainties in the dynamical reconstruction of the merger scenarios. Need: In order to better model the dynamics of merging galaxy cluster systems, and to potentially measure any signal from self-interacting dark matter, we need to obtain more precise measurements on the masses and positions of the dark matter halos involved. Gravitational lensing offers a robust method for mapping the mass in these clusters because it directly measures the gravitational field, and does not depend on the dynamical state of the system that has been disturbed in the merger process. Of the lensing methods, weak gravitational lensing is the only way that we can probe a wide field and measure the total mass of the cluster. However, the precision of conventional weak lensing techniques is currently limited by shape noise (uncertainty in the shear due to the dispersion in the intrinsic shapes and orientations of unlensed galaxies). A possible avenue forward is to eliminate shape noise as a source of uncertainty in shear measurements via a technique to be described below. This would eliminate the largest source of uncertainty in weak lensing analyses, and enable us to obtain mass and position estimates of dark matter halos with a much higher level of precision. Task: In this dissertation we perform statistical clustering, conventional weak lensing analyses, and dynamical reconstruction on the merging galaxy cluster system ZwCl 2341.1+0000 in order to test the capabilities of the dynamical modeling on a complex, multiple merger. We use targeted optical spectroscopy to identify cluster member galaxies, which we then use to model the galaxy substructures. We also obtain a dynamical mass estimate using the galaxy velocity dispersions, and perform weak lensing analyses in the forms of aperture densitometry to place an upper bound on the total cluster mass, and multiple NFW profile halo fitting to approximate the masses and positions of the individual dark matter halos present in the merger. The masses, positions, and line of sight velocities of those clusters are then used to constrain the parameters describing the best fit merger scenario, with radio relic positions and polarization used to further tighten those constraints. We also develop a new method for obtaining weak lensing data from individual source galaxies in the form of shear measurements that are independent of shape noise, and direct measurements of the convergence. We accomplish this by simultaneously modeling the pre-lensing velocity and intensity profiles of a lensed, rotating disk galaxy, and the lensing transform required to distort those into the lensed profiles we observe. We test this method with a host of idealized simulations to characterize its capabilities in a best-case scenario and forecast the possible improvements it can bring to the precision of weak lensing analyses on galaxy clusters. (Abstract shortened by ProQuest.).

Development of a precision reverse offset printing system

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

Kim, Hyunchang; Lee, Eonseok; Choi, Young-Man

2016-01-15

In printed electronics technology, the overlay accuracy of printed patterns is a very important issue when applying printing technology to the production of electric devices. In order to achieve accurate positioning of the printed patterns, this study proposes a novel precision reverse offset printing system. Furthermore, the study evaluates the effects of synchronization and printing force on position errors of the printed patterns, and presents methods of controlling synchronization and printing force so as to eliminate positional errors caused by the above-mentioned reasons. Finally, the printing position repeatability of 0.40 μm and 0.32 μm (x and y direction, respectively) atmore » a sigma level is obtained over the dimension of 100 mm under repeated printing tests with identical printing conditions.« less

Proprioceptive assessment in clinical settings: Evaluation of joint position sense in upper limb post-stroke using a robotic manipulator

PubMed Central

Kager, Simone; Budhota, Aamani; Deshmukh, Vishwanath A.; Kuah, Christopher W. K.; Yam, Lester H. L.; Xiang, Liming; Chua, Karen S. G.; Masia, Lorenzo; Campolo, Domenico

2017-01-01

Proprioception is a critical component for motor functions and directly affects motor learning after neurological injuries. Conventional methods for its assessment are generally ordinal in nature and hence lack sensitivity. Robotic devices designed to promote sensorimotor learning can potentially provide quantitative precise, accurate, and reliable assessments of sensory impairments. In this paper, we investigate the clinical applicability and validity of using a planar 2 degrees of freedom robot to quantitatively assess proprioceptive deficits in post-stroke participants. Nine stroke survivors and nine healthy subjects participated in the study. Participants’ hand was passively moved to the target position guided by the H-Man robot (Criterion movement) and were asked to indicate during a second passive movement towards the same target (Matching movement) when they felt that they matched the target position. The assessment was carried out on a planar surface for movements in the forward and oblique directions in the contralateral and ipsilateral sides of the tested arm. The matching performance was evaluated in terms of error magnitude (absolute and signed) and its variability. Stroke patients showed higher variability in the estimation of the target position compared to the healthy participants. Further, an effect of target was found, with lower absolute errors in the contralateral side. Pairwise comparison between individual stroke participant and control participants showed significant proprioceptive deficits in two patients. The proposed assessment of passive joint position sense was inherently simple and all participants, regardless of motor impairment level, could complete it in less than 10 minutes. Therefore, the method can potentially be carried out to detect changes in proprioceptive deficits in clinical settings. PMID:29161264

How Does My Cellphone GPS Work?-The Physics of Precision Time-Keeping

NASA Astrophysics Data System (ADS)

Chu, Steven

The most precise measurements in all of science are frequency and frequency difference measurements, or alternatively, phase and phase change of electromagnetic waves. Improvements in time-keeping have opened up many horizons in fundamental and applied physics that range from the detection of gravity waves to the melting of glaciers and the depletion of underground aquifers. Precision time keeping has also had important practical applications such as in the navigation, beginning with the determination of the longitude position of sailing ships. We now use our cell phones to help us navigate city streets and hail taxis from Uber and Lyft based on our geographical position within a few meters. How did this come about? What will the new time-keeping technologies enable in the future?

Exact solution and precise asymptotics of a Fisher-KPP type front

NASA Astrophysics Data System (ADS)

Berestycki, Julien; Brunet, Éric; Derrida, Bernard

2018-01-01

The present work concerns a version of the Fisher-KPP equation where the nonlinear term is replaced by a saturation mechanism, yielding a free boundary problem with mixed conditions. Following an idea proposed in Brunet and Derrida (2015 J. Stat. Phys. 161 801), we show that the Laplace transform of the initial condition is directly related to some functional of the front position μt . We then obtain precise asymptotics of the front position by means of singularity analysis. In particular, we recover the so-called Ebert and van Saarloos correction (Ebert and van Saarloos 2000 Physica D 146 1), we obtain an additional term of order log t /t in this expansion, and we give precise conditions on the initial condition for those terms to be present.

Real-Time Precise Point Positioning (RTPPP) with raw observations and its application in real-time regional ionospheric VTEC modeling

NASA Astrophysics Data System (ADS)

Liu, Teng; Zhang, Baocheng; Yuan, Yunbin; Li, Min

2018-01-01

Precise Point Positioning (PPP) is an absolute positioning technology mainly used in post data processing. With the continuously increasing demand for real-time high-precision applications in positioning, timing, retrieval of atmospheric parameters, etc., Real-Time PPP (RTPPP) and its applications have drawn more and more research attention in recent years. This study focuses on the models, algorithms and ionospheric applications of RTPPP on the basis of raw observations, in which high-precision slant ionospheric delays are estimated among others in real time. For this purpose, a robust processing strategy for multi-station RTPPP with raw observations has been proposed and realized, in which real-time data streams and State-Space-Representative (SSR) satellite orbit and clock corrections are used. With the RTPPP-derived slant ionospheric delays from a regional network, a real-time regional ionospheric Vertical Total Electron Content (VTEC) modeling method is proposed based on Adjusted Spherical Harmonic Functions and a Moving-Window Filter. SSR satellite orbit and clock corrections from different IGS analysis centers are evaluated. Ten globally distributed real-time stations are used to evaluate the positioning performances of the proposed RTPPP algorithms in both static and kinematic modes. RMS values of positioning errors in static/kinematic mode are 5.2/15.5, 4.7/17.4 and 12.8/46.6 mm, for north, east and up components, respectively. Real-time slant ionospheric delays from RTPPP are compared with those from the traditional Carrier-to-Code Leveling (CCL) method, in terms of function model, formal precision and between-receiver differences of short baseline. Results show that slant ionospheric delays from RTPPP are more precise and have a much better convergence performance than those from the CCL method in real-time processing. 30 real-time stations from the Asia-Pacific Reference Frame network are used to model the ionospheric VTECs over Australia in real time, with slant ionospheric delays from both RTPPP and CCL methods for comparison. RMS of the VTEC differences between RTPPP/CCL method and CODE final products is 0.91/1.09 TECU, and RMS of the VTEC differences between RTPPP and CCL methods is 0.67 TECU. Slant Total Electron Contents retrieved from different VTEC models are also validated with epoch-differenced Geometry-Free combinations of dual-frequency phase observations, and mean RMS values are 2.14, 2.33 and 2.07 TECU for RTPPP method, CCL method and CODE final products, respectively. This shows the superiority of RTPPP-derived slant ionospheric delays in real-time ionospheric VTEC modeling.

Error measuring system of rotary Inductosyn

NASA Astrophysics Data System (ADS)

Liu, Chengjun; Zou, Jibin; Fu, Xinghe

2008-10-01

The inductosyn is a kind of high-precision angle-position sensor. It has important applications in servo table, precision machine tool and other products. The precision of inductosyn is calibrated by its error. It's an important problem about the error measurement in the process of production and application of the inductosyn. At present, it mainly depends on the method of artificial measurement to obtain the error of inductosyn. Therefore, the disadvantages can't be ignored such as the high labour intensity of the operator, the occurrent error which is easy occurred and the poor repeatability, and so on. In order to solve these problems, a new automatic measurement method is put forward in this paper which based on a high precision optical dividing head. Error signal can be obtained by processing the output signal of inductosyn and optical dividing head precisely. When inductosyn rotating continuously, its zero position error can be measured dynamically, and zero error curves can be output automatically. The measuring and calculating errors caused by man-made factor can be overcome by this method, and it makes measuring process more quickly, exactly and reliably. Experiment proves that the accuracy of error measuring system is 1.1 arc-second (peak - peak value).

Studies on fast triggering and high precision tracking with Resistive Plate Chambers

NASA Astrophysics Data System (ADS)

Aielli, G.; Ball, R.; Bilki, B.; Chapman, J. W.; Cardarelli, R.; Dai, T.; Diehl, E.; Dubbert, J.; Ferretti, C.; Feng, H.; Francis, K.; Guan, L.; Han, L.; Hou, S.; Levin, D.; Li, B.; Liu, L.; Paolozzi, L.; Repond, J.; Roloff, J.; Santonico, R.; Song, H. Y.; Wang, X. L.; Wu, Y.; Xia, L.; Xu, L.; Zhao, T.; Zhao, Z.; Zhou, B.; Zhu, J.

2013-06-01

We report on studies of fast triggering and high precision tracking using Resistive Plate Chambers (RPCs). Two beam tests were carried out with the 180 GeV/c muon beam at CERN using glass RPCs with gas gaps of 1.15 mm and equipped with readout strips with 1.27 mm pitch. This is the first beam test of RPCs with fine-pitch readout strips that explores precision tracking and triggering capabilities. RPC signals were acquired with precision timing and charge integrating readout electronics at both ends of the strips. The time resolution was measured to be better than 600 ps and the average spatial resolution was found to be 220 μm using charge information and 287 μm only using signal arrival time information. The dual-ended readout allows the determination of the average and the difference of the signal arrival times. The average time was found to be independent of the incident particle position along the strip and is useful for triggering purposes. The time difference yielded a determination of the hit position with a precision of 7.5 mm along the strip. These results demonstrate the feasibility using RPCs for fast and high-resolution triggering and tracking.

Lawrence Livermore National Laboratory ULTRA-350 Test Bed

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

Hopkins, D J; Wulff, T A; Carlisle, K

2001-04-10

LLNL has many in-house designed high precision machine tools. Some of these tools include the Large Optics Diamond Turning Machine (LODTM) [1], Diamond Turning Machine No.3 (DTM-3) and two Precision Engineering Research Lathes (PERL-1 and PERL-11). These machines have accuracy in the sub-micron range and in most cases position resolution in the couple of nanometers range. All of these machines are built with similar underlying technologies. The machines use capstan drive technology, laser interferometer position feedback, tachometer velocity feedback, permanent magnet (PM) brush motors and analog velocity and position loop servo compensation [2]. The machine controller does not perform anymore » servo compensation it simply computes the differences between the commanded position and the actual position (the following error) and sends this to a D/A for the analog servo position loop. LLNL is designing a new high precision diamond turning machine. The machine is called the ULTRA 350 [3]. In contrast to many of the proven technologies discussed above, the plan for the new machine is to use brushless linear motors, high precision linear scales, machine controller motor commutation and digital servo compensation for the velocity and position loops. Although none of these technologies are new and have been in use in industry, applications of these technologies to high precision diamond turning is limited. To minimize the risks of these technologies in the new machine design, LLNL has established a test bed to evaluate these technologies for application in high precision diamond turning. The test bed is primarily composed of commercially available components. This includes the slide with opposed hydrostatic bearings, the oil system, the brushless PM linear motor, the two-phase input three-phase output linear motor amplifier and the system controller. The linear scales are not yet commercially available but use a common electronic output format. As of this writing, the final verdict for the use of these technologies is still out but the first part of the work has been completed with promising results. The goal of this part of the work was to close a servo position loop around a slide incorporating these technologies and to measure the performance. This paper discusses the tests that were setup for system evaluation and the results of the measurements made. Some very promising results include; slide positioning to nanometer level and slow speed slide direction reversal at less than 100nm/min with no observed discontinuities. This is very important for machine contouring in diamond turning. As a point of reference, at 100 nm/min it would take the slide almost 7 years to complete the full designed travel of 350 mm. This speed has been demonstrated without the use of a velocity sensor. The velocity is derived from the position sensor. With what has been learned on the test bed, the paper finishes with a brief comparison of the old and new technologies. The emphasis of this comparison will be on the servo performance as illustrated with bode plot diagrams.« less

Lawrence Livermore National Laboratory ULTRA-350 Test Bed

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

Hopkins, D J; Wulff, T A; Carlisle, K

2001-04-10

LLNL has many in-house designed high precision machine tools. Some of these tools include the Large Optics Diamond Turning Machine (LODTM) [1], Diamond Turning Machine No.3 (DTM-3) and two Precision Engineering Research Lathes (PERL-I and PERL-II). These machines have accuracy in the sub-micron range and in most cases position resolution in the couple of nanometers range. All of these machines are built with similar underlying technologies. The machines use capstan drive technology, laser interferometer position feedback, tachometer velocity feedback, permanent magnet (PM) brush motors and analog velocity and position loop servo compensation [2]. The machine controller does not perform anymore » servo compensation it simply computes the differences between the commanded position and the actual position (the following error) and sends this to a D/A for the analog servo position loop. LLNL is designing a new high precision diamond turning machine. The machine is called the ULTRA 350 [3]. In contrast to many of the proven technologies discussed above, the plan for the new machine is to use brushless linear motors, high precision linear scales, machine controller motor commutation and digital servo compensation for the velocity and position loops. Although none of these technologies are new and have been in use in industry, applications of these technologies to high precision diamond turning is limited. To minimize the risks of these technologies in the new machine design, LLNL has established a test bed to evaluate these technologies for application in high precision diamond turning. The test bed is primarily composed of commercially available components. This includes the slide with opposed hydrostatic bearings, the oil system, the brushless PM linear motor, the two-phase input three-phase output linear motor amplifier and the system controller. The linear scales are not yet commercially available but use a common electronic output format. As of this writing, the final verdict for the use of these technologies is still out but the first part of the work has been completed with promising results. The goal of this part of the work was to close a servo position loop around a slide incorporating these technologies and to measure the performance. This paper discusses the tests that were setup for system evaluation and the results of the measurements made. Some very promising results include; slide positioning to nanometer level and slow speed slide direction reversal at less than 100nm/min with no observed discontinuities. This is very important for machine contouring in diamond turning. As a point of reference, at 100 nm/min it would take the slide almost 7 years to complete the full designed travel of 350 mm. This speed has been demonstrated without the use of a velocity sensor. The velocity is derived from the position sensor. With what has been learned on the test bed, the paper finishes with a brief comparison of the old and new technologies. The emphasis of this comparison will be on the servo performance as illustrated with bode plot diagrams.« less

Surgical positioning of orthodontic mini-implants with guides fabricated on models replicated with cone-beam computed tomography.

PubMed

Kim, Seong-Hun; Choi, Yong-Suk; Hwang, Eui-Hwan; Chung, Kyu-Rhim; Kook, Yoon-Ah; Nelson, Gerald

2007-04-01

This article illustrates a new surgical guide system that uses cone-beam computed tomography (CBCT) images to replicate dental models; surgical guides for the proper positioning of orthodontic mini-implants were fabricated on the replicas, and the guides were used for precise placement. The indications, efficacy, and possible complications of this method are discussed. Patients who were planning to have orthodontic mini-implant treatment were recruited for this study. A CBCT system (PSR 9000N, Asahi Roentgen, Kyoto, Japan) was used to acquire virtual slices of the posterior maxilla that were 0.1 to 0.15 mm thick. Color 3-dimensional rapid prototyping was used to differentiate teeth, alveolus, and maxillary sinus wall. A surgical guide for the mini-implant was fabricated on the replica model. Proper positioning for mini-implants on the posterior maxilla was determined by viewing the CBCT images. The surgical guide was placed on the clinical site, and it allowed precise pilot drilling and accurate placement of the mini-implant. CBCT imaging allows remarkably lower radiation doses and thinner acquisition slices compared with medical computed tomography. Virtually reproduced replica models enable precise planning for mini-implant positions in anatomically complex sites.

On the convergence of ionospheric constrained precise point positioning (IC-PPP) based on undifferential uncombined raw GNSS observations.

PubMed

Zhang, Hongping; Gao, Zhouzheng; Ge, Maorong; Niu, Xiaoji; Huang, Ling; Tu, Rui; Li, Xingxing

2013-11-18

Precise Point Positioning (PPP) has become a very hot topic in GNSS research and applications. However, it usually takes about several tens of minutes in order to obtain positions with better than 10 cm accuracy. This prevents PPP from being widely used in real-time kinematic positioning services, therefore, a large effort has been made to tackle the convergence problem. One of the recent approaches is the ionospheric delay constrained precise point positioning (IC-PPP) that uses the spatial and temporal characteristics of ionospheric delays and also delays from an a priori model. In this paper, the impact of the quality of ionospheric models on the convergence of IC-PPP is evaluated using the IGS global ionospheric map (GIM) updated every two hours and a regional satellite-specific correction model. Furthermore, the effect of the receiver differential code bias (DCB) is investigated by comparing the convergence time for IC-PPP with and without estimation of the DCB parameter. From the result of processing a large amount of data, on the one hand, the quality of the a priori ionosphere delays plays a very important role in IC-PPP convergence. Generally, regional dense GNSS networks can provide more precise ionosphere delays than GIM and can consequently reduce the convergence time. On the other hand, ignoring the receiver DCB may considerably extend its convergence, and the larger the DCB, the longer the convergence time. Estimating receiver DCB in IC-PPP is a proper way to overcome this problem. Therefore, current IC-PPP should be enhanced by estimating receiver DCB and employing regional satellite-specific ionospheric correction models in order to speed up its convergence for more practical applications.

On the Convergence of Ionospheric Constrained Precise Point Positioning (IC-PPP) Based on Undifferential Uncombined Raw GNSS Observations

PubMed Central

Zhang, Hongping; Gao, Zhouzheng; Ge, Maorong; Niu, Xiaoji; Huang, Ling; Tu, Rui; Li, Xingxing

2013-01-01

Precise Point Positioning (PPP) has become a very hot topic in GNSS research and applications. However, it usually takes about several tens of minutes in order to obtain positions with better than 10 cm accuracy. This prevents PPP from being widely used in real-time kinematic positioning services, therefore, a large effort has been made to tackle the convergence problem. One of the recent approaches is the ionospheric delay constrained precise point positioning (IC-PPP) that uses the spatial and temporal characteristics of ionospheric delays and also delays from an a priori model. In this paper, the impact of the quality of ionospheric models on the convergence of IC-PPP is evaluated using the IGS global ionospheric map (GIM) updated every two hours and a regional satellite-specific correction model. Furthermore, the effect of the receiver differential code bias (DCB) is investigated by comparing the convergence time for IC-PPP with and without estimation of the DCB parameter. From the result of processing a large amount of data, on the one hand, the quality of the a priori ionosphere delays plays a very important role in IC-PPP convergence. Generally, regional dense GNSS networks can provide more precise ionosphere delays than GIM and can consequently reduce the convergence time. On the other hand, ignoring the receiver DCB may considerably extend its convergence, and the larger the DCB, the longer the convergence time. Estimating receiver DCB in IC-PPP is a proper way to overcome this problem. Therefore, current IC-PPP should be enhanced by estimating receiver DCB and employing regional satellite-specific ionospheric correction models in order to speed up its convergence for more practical applications. PMID:24253190

Adaptive nonsingular terminal sliding mode controller for micro/nanopositioning systems driven by linear piezoelectric ceramic motors.

PubMed

Safa, Alireza; Abdolmalaki, Reza Yazdanpanah; Shafiee, Saeed; Sadeghi, Behzad

2018-06-01

In the field of nanotechnology, there is a growing demand to provide precision control and manipulation of devices with the ability to interact with complex and unstructured environments at micro/nano-scale. As a result, ultrahigh-precision positioning stages have been turned into a key requirement of nanotechnology. In this paper, linear piezoelectric ceramic motors (LPCMs) are adopted to drive micro/nanopositioning stages since they have the ability to achieve high precision in addition to being versatile to be implemented over a wide range of applications. In the establishment of a control scheme for such manipulation systems, the presence of friction, parameter uncertainties, and external disturbances prevent the systems from providing the desired positioning accuracy. The work in this paper focuses on the development of a control framework that addresses these issues as it uses the nonsingular terminal sliding mode technique for the precise position tracking problem of an LPCM-driven positioning stage with friction, uncertain parameters, and external disturbances. The developed control algorithm exhibits the following two attractive features. First, upper bounds of system uncertainties/perturbations are adaptively estimated in the proposed controller; thus, prior knowledge about uncertainty/disturbance bounds is not necessary. Second, the discontinuous signum function is transferred to the time derivative of the control input and the continuous control signal is obtained after integration; consequently, the chattering phenomenon, which presents a major handicap to the implementation of conventional sliding mode control in real applications, is alleviated without deteriorating the robustness of the system. The stability of the controlled system is analyzed, and the convergence of the position tracking error to zero is analytically proven. The proposed control strategy is experimentally validated and compared to the existing control approaches. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Precision controllability of the YF-17 airplane

NASA Technical Reports Server (NTRS)

Sisk, T. R.; Mataeny, N. W.

1980-01-01

A flying qualities evaluation conducted on the YF-17 airplane permitted assessment of its precision controllability in the transonic flight regime over the allowable angle of attack range. The precision controllability (tailchase tracking) study was conducted in constant-g and windup turn tracking maneuvers with the command augmentation system (CAS) on, automatic maneuver flaps, and the caged pipper gunsight depressed 70 mils. This study showed that the YF-17 airplane tracks essentially as well at 7 g's to 8 g's as earlier fighters did at 4 g's to 5 g's before they encountered wing rock. The pilots considered the YF-17 airplane one of the best tracking airplanes they had flown. Wing rock at the higher angles of attack degraded tracking precision, and lack of control harmony made precision controllability more difficult. The revised automatic maneuver flap schedule incorporated in the airplane at the time of the tests did not appear to be optimum. The largest tracking errors and greatest pilot workload occurred at high normal load factors at low angles of attack. The pilots reported that the high-g maneuvers caused some tunnel vision and that they found it difficult to think clearly after repeated maneuvers.

Wireless inertial measurement of head kinematics in freely-moving rats

PubMed Central

Pasquet, Matthieu O.; Tihy, Matthieu; Gourgeon, Aurélie; Pompili, Marco N.; Godsil, Bill P.; Léna, Clément; Dugué, Guillaume P.

2016-01-01

While miniature inertial sensors offer a promising means for precisely detecting, quantifying and classifying animal behaviors, versatile inertial sensing devices adapted for small, freely-moving laboratory animals are still lacking. We developed a standalone and cost-effective platform for performing high-rate wireless inertial measurements of head movements in rats. Our system is designed to enable real-time bidirectional communication between the headborne inertial sensing device and third party systems, which can be used for precise data timestamping and low-latency motion-triggered applications. We illustrate the usefulness of our system in diverse experimental situations. We show that our system can be used for precisely quantifying motor responses evoked by external stimuli, for characterizing head kinematics during normal behavior and for monitoring head posture under normal and pathological conditions obtained using unilateral vestibular lesions. We also introduce and validate a novel method for automatically quantifying behavioral freezing during Pavlovian fear conditioning experiments, which offers superior performance in terms of precision, temporal resolution and efficiency. Thus, this system precisely acquires movement information in freely-moving animals, and can enable objective and quantitative behavioral scoring methods in a wide variety of experimental situations. PMID:27767085

Site-selective substitutional doping with atomic precision on stepped Al (111) surface by single-atom manipulation

PubMed Central

2014-01-01

In fabrication of nano- and quantum devices, it is sometimes critical to position individual dopants at certain sites precisely to obtain the specific or enhanced functionalities. With first-principles simulations, we propose a method for substitutional doping of individual atom at a certain position on a stepped metal surface by single-atom manipulation. A selected atom at the step of Al (111) surface could be extracted vertically with an Al trimer-apex tip, and then the dopant atom will be positioned to this site. The details of the entire process including potential energy curves are given, which suggests the reliability of the proposed single-atom doping method. PMID:24899871

Site-selective substitutional doping with atomic precision on stepped Al (111) surface by single-atom manipulation.

PubMed

Chen, Chang; Zhang, Jinhu; Dong, Guofeng; Shao, Hezhu; Ning, Bo-Yuan; Zhao, Li; Ning, Xi-Jing; Zhuang, Jun

2014-01-01

In fabrication of nano- and quantum devices, it is sometimes critical to position individual dopants at certain sites precisely to obtain the specific or enhanced functionalities. With first-principles simulations, we propose a method for substitutional doping of individual atom at a certain position on a stepped metal surface by single-atom manipulation. A selected atom at the step of Al (111) surface could be extracted vertically with an Al trimer-apex tip, and then the dopant atom will be positioned to this site. The details of the entire process including potential energy curves are given, which suggests the reliability of the proposed single-atom doping method.

Application of global positioning system to determination of tectonic plate movements and crustal deformations

NASA Technical Reports Server (NTRS)

Anderle, R. J.

1978-01-01

It is shown that pseudo-range measurements to four GPS satellites based on correlation of the pseudo random code transmissions from the satellites can be used to determine the relative position of ground stations which are separated by several hundred kilometers to a precision at the centimeter level. Carrier signal measurements during the course of passage of satellites over a pair of stations also yield centimeter precision in the relative position, but oscillator instabilities limit the accuracy. The accuracy of solutions based on either type of data is limited by unmodeled tropospheric refraction effects which would reach 5 centimeters at low elevation angles for widely separated stations.

A hybrid stochastic approach for self-location of wireless sensors in indoor environments.

PubMed

Lloret, Jaime; Tomas, Jesus; Garcia, Miguel; Canovas, Alejandro

2009-01-01

Indoor location systems, especially those using wireless sensor networks, are used in many application areas. While the need for these systems is widely proven, there is a clear lack of accuracy. Many of the implemented applications have high errors in their location estimation because of the issues arising in the indoor environment. Two different approaches had been proposed using WLAN location systems: on the one hand, the so-called deductive methods take into account the physical properties of signal propagation. These systems require a propagation model, an environment map, and the position of the radio-stations. On the other hand, the so-called inductive methods require a previous training phase where the system learns the received signal strength (RSS) in each location. This phase can be very time consuming. This paper proposes a new stochastic approach which is based on a combination of deductive and inductive methods whereby wireless sensors could determine their positions using WLAN technology inside a floor of a building. Our goal is to reduce the training phase in an indoor environment, but, without an loss of precision. Finally, we compare the measurements taken using our proposed method in a real environment with the measurements taken by other developed systems. Comparisons between the proposed system and other hybrid methods are also provided.

The Socio-Moral Image Database (SMID): A novel stimulus set for the study of social, moral and affective processes

PubMed Central

Bode, Stefan; Murawski, Carsten; Laham, Simon M.

2018-01-01

A major obstacle for the design of rigorous, reproducible studies in moral psychology is the lack of suitable stimulus sets. Here, we present the Socio-Moral Image Database (SMID), the largest standardized moral stimulus set assembled to date, containing 2,941 freely available photographic images, representing a wide range of morally (and affectively) positive, negative and neutral content. The SMID was validated with over 820,525 individual judgments from 2,716 participants, with normative ratings currently available for all images on affective valence and arousal, moral wrongness, and relevance to each of the five moral values posited by Moral Foundations Theory. We present a thorough analysis of the SMID regarding (1) inter-rater consensus, (2) rating precision, and (3) breadth and variability of moral content. Additionally, we provide recommendations for use aimed at efficient study design and reproducibility, and outline planned extensions to the database. We anticipate that the SMID will serve as a useful resource for psychological, neuroscientific and computational (e.g., natural language processing or computer vision) investigations of social, moral and affective processes. The SMID images, along with associated normative data and additional resources are available at https://osf.io/2rqad/. PMID:29364985

A Hybrid Stochastic Approach for Self-Location of Wireless Sensors in Indoor Environments

PubMed Central

Lloret, Jaime; Tomas, Jesus; Garcia, Miguel; Canovas, Alejandro

2009-01-01

Indoor location systems, especially those using wireless sensor networks, are used in many application areas. While the need for these systems is widely proven, there is a clear lack of accuracy. Many of the implemented applications have high errors in their location estimation because of the issues arising in the indoor environment. Two different approaches had been proposed using WLAN location systems: on the one hand, the so-called deductive methods take into account the physical properties of signal propagation. These systems require a propagation model, an environment map, and the position of the radio-stations. On the other hand, the so-called inductive methods require a previous training phase where the system learns the received signal strength (RSS) in each location. This phase can be very time consuming. This paper proposes a new stochastic approach which is based on a combination of deductive and inductive methods whereby wireless sensors could determine their positions using WLAN technology inside a floor of a building. Our goal is to reduce the training phase in an indoor environment, but, without an loss of precision. Finally, we compare the measurements taken using our proposed method in a real environment with the measurements taken by other developed systems. Comparisons between the proposed system and other hybrid methods are also provided. PMID:22412334

Application of lidar and optical data for oil palm plantation management in Malaysia

NASA Astrophysics Data System (ADS)

Shafri, Helmi Z. M.; Ismail, Mohd Hasmadi; Razi, Mohd Khairil M.; Anuar, Mohd Izzuddin; Ahmad, Abdul Rahman

2012-11-01

Proper oil palm plantation management is crucial for Malaysia as the country depends heavily on palm oil as a major source of national income. Precision agriculture is considered as one of the approaches that can be adopted to improve plantation practices for plantation managers such as the government-owned FELDA. However, currently the implementation of precision agriculture based on remote sensing and GIS is still lacking. This study explores the potential of the use of LiDAR and optical remote sensing data for plantation road and terrain planning for planting purposes. Traditional approaches use land surveying techniques that are time consuming and costly for vast plantation areas. The first ever airborne LiDAR and multispectral survey for oil palm plantation was carried out in early 2012 to test its feasibility. Preliminary results show the efficiency of such technology in demanding engineering and agricultural requirements of oil palm plantation. The most significant advantage of the approach is that it allows plantation managers to accurately plan the plantation road and determine the planting positions of new oil palm seedlings. Furthermore, this creates for the first time, digital database of oil palm estate and the airborne imagery can also be used for related activities such as oil palm tree inventory and detection of palm diseases. This work serves as the pioneer towards a more frequent application of LiDAR and multispectral data for oil palm plantation in Malaysia.

Improving BeiDou real-time precise point positioning with numerical weather models

NASA Astrophysics Data System (ADS)

Lu, Cuixian; Li, Xingxing; Zus, Florian; Heinkelmann, Robert; Dick, Galina; Ge, Maorong; Wickert, Jens; Schuh, Harald

2017-09-01

Precise positioning with the current Chinese BeiDou Navigation Satellite System is proven to be of comparable accuracy to the Global Positioning System, which is at centimeter level for the horizontal components and sub-decimeter level for the vertical component. But the BeiDou precise point positioning (PPP) shows its limitation in requiring a relatively long convergence time. In this study, we develop a numerical weather model (NWM) augmented PPP processing algorithm to improve BeiDou precise positioning. Tropospheric delay parameters, i.e., zenith delays, mapping functions, and horizontal delay gradients, derived from short-range forecasts from the Global Forecast System of the National Centers for Environmental Prediction (NCEP) are applied into BeiDou real-time PPP. Observational data from stations that are capable of tracking the BeiDou constellation from the International GNSS Service (IGS) Multi-GNSS Experiments network are processed, with the introduced NWM-augmented PPP and the standard PPP processing. The accuracy of tropospheric delays derived from NCEP is assessed against with the IGS final tropospheric delay products. The positioning results show that an improvement in convergence time up to 60.0 and 66.7% for the east and vertical components, respectively, can be achieved with the NWM-augmented PPP solution compared to the standard PPP solutions, while only slight improvement in the solution convergence can be found for the north component. A positioning accuracy of 5.7 and 5.9 cm for the east component is achieved with the standard PPP that estimates gradients and the one that estimates no gradients, respectively, in comparison to 3.5 cm of the NWM-augmented PPP, showing an improvement of 38.6 and 40.1%. Compared to the accuracy of 3.7 and 4.1 cm for the north component derived from the two standard PPP solutions, the one of the NWM-augmented PPP solution is improved to 2.0 cm, by about 45.9 and 51.2%. The positioning accuracy for the up component improves from 11.4 and 13.2 cm with the two standard PPP solutions to 8.0 cm with the NWM-augmented PPP solution, an improvement of 29.8 and 39.4%, respectively.

Geometrically constrained kinematic global navigation satellite systems positioning: Implementation and performance

NASA Astrophysics Data System (ADS)

Asgari, Jamal; Mohammadloo, Tannaz H.; Amiri-Simkooei, Ali Reza

2015-09-01

GNSS kinematic techniques are capable of providing precise coordinates in extremely short observation time-span. These methods usually determine the coordinates of an unknown station with respect to a reference one. To enhance the precision, accuracy, reliability and integrity of the estimated unknown parameters, GNSS kinematic equations are to be augmented by possible constraints. Such constraints could be derived from the geometric relation of the receiver positions in motion. This contribution presents the formulation of the constrained kinematic global navigation satellite systems positioning. Constraints effectively restrict the definition domain of the unknown parameters from the three-dimensional space to a subspace defined by the equation of motion. To test the concept of the constrained kinematic positioning method, the equation of a circle is employed as a constraint. A device capable of moving on a circle was made and the observations from 11 positions on the circle were analyzed. Relative positioning was conducted by considering the center of the circle as the reference station. The equation of the receiver's motion was rewritten in the ECEF coordinates system. A special attention is drawn onto how a constraint is applied to kinematic positioning. Implementing the constraint in the positioning process provides much more precise results compared to the unconstrained case. This has been verified based on the results obtained from the covariance matrix of the estimated parameters and the empirical results using kinematic positioning samples as well. The theoretical standard deviations of the horizontal components are reduced by a factor ranging from 1.24 to 2.64. The improvement on the empirical standard deviation of the horizontal components ranges from 1.08 to 2.2.

High-Precision Global Geodetic Systems: Revolution And Revelation In Fluid And 'Solid' Earth Tracking (Invited)

NASA Astrophysics Data System (ADS)

Minster, J. H.; Altamimi, Z.; Blewitt, G.; Carter, W. E.; Cazenave, A. A.; Davis, J. L.; Dragert, H.; Feary, D. A.; Herring, T.; Larson, K. M.; Ries, J. C.; Sandwell, D. T.; Wahr, J. M.

2009-12-01

Over the past half-century, space geodetic technologies have changed profoundly the way we look at the planet, not only in the matter of details and accuracy, but also in the matter of how the entire planet changes with time, even on “human” time scales. The advent of space geodesy has provided exquisite images of the ever-changing land and ocean topography and global gravity field of the planet. We now enjoy an International Terrestrial Reference System with a time-dependent geocenter position accurate to a few millimeters. We can image small and large tectonic deformations of the surface before, during, and after earthquakes and volcanic eruptions. We measure both the past subtle changes as well as the recent dramatic changes in the ice sheets, and track global and regional sea-level change to a precision of a millimeter per year or better. The remarkable achievements of Earth observing missions over the past two decades, and the success of future international missions described in the Decadal Survey depend both implicitly and explicitly on the continued availability and enhancement of a reliable and resilient global infrastructure for precise geodesy, and on ongoing advances in geodetic science that are linked to it. This allows us to deal with global scientific, technological and social issues such as climate change and natural hazards, but the impact of the global precise geodetic infrastructure also permeates our everyday lives. Nowadays drivers, aviators, and sailors can determine their positions inexpensively to meter precision in real time, anywhere on the planet. In the foreseeable future, not only will we be able to know a vehicle’s position to centimeter accuracy in real time, but also to control that position, and thus introduce autonomous navigation systems for many tasks which are beyond the reach of “manual” navigation capabilities. This vision will only be realized with sustained international support of the precise global geodetic infrastructure, of the associated technological advances, and of the concomitant fundamental geodetic research.

In vivo glenohumeral analysis using 3D MRI models and a flexible software tool: feasibility and precision.

PubMed

Busse, Harald; Thomas, Michael; Seiwerts, Matthias; Moche, Michael; Busse, Martin W; von Salis-Soglio, Georg; Kahn, Thomas

2008-01-01

To implement a PC-based morphometric analysis platform and to evaluate the feasibility and precision of MRI measurements of glenohumeral translation. Using a vertically open 0.5T MRI scanner, the shoulders of 10 healthy subjects were scanned in apprehension (AP) and in neutral position (NP), respectively. Surface models of the humeral head (HH) and the glenoid cavity (GC) were created from segmented MR images by three readers. Glenohumeral translation was determined by the projection point of the manually fitted HH center on the GC plane defined by the two main principal axes of the GC model. Positional precision, given as mean (extreme value at 95% confidence level), was 0.9 (1.8) mm for the HH center and 0.7 (1.6) mm for the GC centroid; angular GC precision was 1.3 degrees (2.3 degrees ) for the normal and about 4 degrees (7 degrees ) for the anterior and superior coordinate axes. The two-dimensional (2D) precision of the HH projection point was 1.1 (2.2) mm. A significant HH translation between AP and NP was found. Despite a limited quality of the underlying model data, our PC-based analysis platform allows a precise morphometric analysis of the glenohumeral joint. The software is easily extendable and may potentially be used for an objective evaluation of therapeutical measures.

Nuclear astrophysics in the laboratory and in the universe

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

Champagne, A. E., E-mail: artc@physics.unc.edu; Iliadis, C.; Longland, R.

Nuclear processes drive stellar evolution and so nuclear physics, stellar models and observations together allow us to describe the inner workings of stars and their life stories. This Information on nuclear reaction rates and nuclear properties are critical ingredients in addressing most questions in astrophysics and often the nuclear database is incomplete or lacking the needed precision. Direct measurements of astrophysically-interesting reactions are necessary and the experimental focus is on improving both sensitivity and precision. In the following, we review recent results and approaches taken at the Laboratory for Experimental Nuclear Astrophysics (LENA, http://research.physics.unc.edu/project/nuclearastro/Welcome.html )

Medical Device for Automated Prick Test Reading.

PubMed

Justo, Xabier; Diaz, Inaki; Gil, Jorge Juan; Gastaminza, Gabriel

2018-05-01

Allergy tests are routinely performed in most hospitals everyday. However, measuring the outcomes of these tests is still a very laborious manual task. Current methods and systems lack of precision and repeatability. This paper presents a novel mechatronic system that is able to scan a patient's entire arm and provide allergists with precise measures of wheals for diagnosis. The device is based on 3-D laser technology and specific algorithms have been developed to process the information gathered. This system aims to automate the reading of skin prick tests and make gains in speed, accuracy, and reliability. Several experiments have been performed to evaluate the performance of the system.

Comparative analysis of positioning and zenith total delay retrieval using GPS-, GLONASS-only, and GPS/GLONASS combined precise point positioning

NASA Astrophysics Data System (ADS)

Zhou, Feng; Li, Xingxing; Cai, Miaomiao; Chen, Wen; Dong, Danan; Schuh, Harald

2017-04-01

Since October 2011, the Russian GLONASS has been revitalized and is now fully operational with 24 satellites in orbit. It is critical to assess the benefits and problems of using GLONASS observations (i.e. GLONASS-only or combined GPS/GLONASS) for precise positioning and zenith total delay (ZTD) retrieval on a global scale using the precise point positioning (PPP) technique. In this contribution, extensive evaluations are conducted with GNSS data sets collected from 251 globally distributed stations of the International GNSS Service (IGS) network in July 2016. The stations are divided into 30 groups by antenna/radome types to investigate whether there are antenna/radome-dependent biases in position and ZTD results derived from GLONASS-only PPP. The positioning results do not show obvious antenna/radome-dependent biases except the stations with JAV_RINGANT_G3T/NONE. The averaged biases of the stations with JAV_RINGANT_G3T/NONE in horizontal component especially in north component can even achieve -9.0 mm. The standard deviation (STD) and root mean square (RMS) are used as indicators of positioning repeatability and accuracy, respectively. Compared with GPS-only PPP, smaller averaged STD and RMS values of GLONASS-only PPP are achieved in horizontal component, while larger ones in vertical component. Furthermore, the STD and RMS values of GPS/GLONASS combined PPP solutions are the smallest in horizontal and vertical components, indicating that adding GLONASS observations can achieve better positioning performance than GPS-only PPP. Meanwhile, better positioning repeatability and accuracy are found in north component than that in east component, which may be caused by the configuration of GNSS satellite orbit. With respect to GPS-only PPP-derived ZTD, the ZTD biases, accuracy, and correlation derived from GLONASS-only and GPS/GLONASS PPP solutions are antenna/radome-independent, while the biases and accuracy are slightly latitude- or Geometric Dilution of Precisions (GDOP)-dependent, as well as the ZTD correlation are highly latitude- or GDOP-dependent. We also studied the impact of the chosen elevation cutoff angles on the positioning and ZTD retrieval. GLONASS-only PPP is found more sensitive with the elevation cutoff angles than GPS-only PPP.

BDS Precise Point Positioning for Seismic Displacements Monitoring: Benefit from the High-Rate Satellite Clock Corrections

PubMed Central

Geng, Tao; Su, Xing; Fang, Rongxin; Xie, Xin; Zhao, Qile; Liu, Jingnan

2016-01-01

In order to satisfy the requirement of high-rate high-precision applications, 1 Hz BeiDou Navigation Satellite System (BDS) satellite clock corrections are generated based on precise orbit products, and the quality of the generated clock products is assessed by comparing with those from the other analysis centers. The comparisons show that the root mean square (RMS) of clock errors of geostationary Earth orbits (GEO) is about 0.63 ns, whereas those of inclined geosynchronous orbits (IGSO) and medium Earth orbits (MEO) are about 0.2–0.3 ns and 0.1 ns, respectively. Then, the 1 Hz clock products are used for BDS precise point positioning (PPP) to retrieve seismic displacements of the 2015 Mw 7.8 Gorkha, Nepal, earthquake. The derived seismic displacements from BDS PPP are consistent with those from the Global Positioning System (GPS) PPP, with RMS of 0.29, 0.38, and 1.08 cm in east, north, and vertical components, respectively. In addition, the BDS PPP solutions with different clock intervals of 1 s, 5 s, 30 s, and 300 s are processed and compared with each other. The results demonstrate that PPP with 300 s clock intervals is the worst and that with 1 s clock interval is the best. For the scenario of 5 s clock intervals, the precision of PPP solutions is almost the same to 1 s results. Considering the time consumption of clock estimates, we suggest that 5 s clock interval is competent for high-rate BDS solutions. PMID:27999384

A Tale of Two Morphs: Modeling Pollen Transfer, Magic Traits, and Reproductive Isolation in Parapatry

PubMed Central

Haller, Benjamin C.; de Vos, Jurriaan M.; Keller, Barbara; Hendry, Andrew P.; Conti, Elena

2014-01-01

The evolution of the flower is commonly thought to have spurred angiosperm diversification. Similarly, particular floral traits might have promoted diversification within specific angiosperm clades. We hypothesize that traits promoting the precise positional transfer of pollen between flowers might promote diversification. In particular, precise pollen transfer might produce partial reproductive isolation that facilitates adaptive divergence between parapatric populations differing in their reproductive-organ positions. We investigate this hypothesis with an individual-based model of pollen transfer dynamics associated with heterostyly, a floral syndrome that depends on precise pollen transfer. Our model shows that precise pollen transfer can cause sexual selection leading to divergence in reproductive-organ positions between populations served by different pollinators, pleiotropically causing an increase in reproductive isolation through a “magic trait” mechanism. Furthermore, this increased reproductive isolation facilitates adaptive divergence between the populations in an unlinked, ecologically selected trait. In a different pollination scenario, however, precise pollen transfer causes a decrease in adaptive divergence by promoting asymmetric gene flow. Our results highlight the idea that magic traits are not “magic” in isolation; in particular, the effect size of magic traits in speciation depends on the external environment, and also on other traits that modify the strength of the magic trait's influence on non-random mating. Overall, we show that the evolutionary consequences of pollen transfer dynamics can depend strongly on the available pollinator fauna and on the morphological fit between flowers and pollinators. Furthermore, our results illustrate the potential importance of even weak reproductive isolating barriers in facilitating adaptive divergence. PMID:25211280

BDS Precise Point Positioning for Seismic Displacements Monitoring: Benefit from the High-Rate Satellite Clock Corrections.

PubMed

Geng, Tao; Su, Xing; Fang, Rongxin; Xie, Xin; Zhao, Qile; Liu, Jingnan

2016-12-20

In order to satisfy the requirement of high-rate high-precision applications, 1 Hz BeiDou Navigation Satellite System (BDS) satellite clock corrections are generated based on precise orbit products, and the quality of the generated clock products is assessed by comparing with those from the other analysis centers. The comparisons show that the root mean square (RMS) of clock errors of geostationary Earth orbits (GEO) is about 0.63 ns, whereas those of inclined geosynchronous orbits (IGSO) and medium Earth orbits (MEO) are about 0.2-0.3 ns and 0.1 ns, respectively. Then, the 1 Hz clock products are used for BDS precise point positioning (PPP) to retrieve seismic displacements of the 2015 Mw 7.8 Gorkha, Nepal, earthquake. The derived seismic displacements from BDS PPP are consistent with those from the Global Positioning System (GPS) PPP, with RMS of 0.29, 0.38, and 1.08 cm in east, north, and vertical components, respectively. In addition, the BDS PPP solutions with different clock intervals of 1 s, 5 s, 30 s, and 300 s are processed and compared with each other. The results demonstrate that PPP with 300 s clock intervals is the worst and that with 1 s clock interval is the best. For the scenario of 5 s clock intervals, the precision of PPP solutions is almost the same to 1 s results. Considering the time consumption of clock estimates, we suggest that 5 s clock interval is competent for high-rate BDS solutions.

A tale of two morphs: modeling pollen transfer, magic traits, and reproductive isolation in parapatry.

PubMed

Haller, Benjamin C; de Vos, Jurriaan M; Keller, Barbara; Hendry, Andrew P; Conti, Elena

2014-01-01

The evolution of the flower is commonly thought to have spurred angiosperm diversification. Similarly, particular floral traits might have promoted diversification within specific angiosperm clades. We hypothesize that traits promoting the precise positional transfer of pollen between flowers might promote diversification. In particular, precise pollen transfer might produce partial reproductive isolation that facilitates adaptive divergence between parapatric populations differing in their reproductive-organ positions. We investigate this hypothesis with an individual-based model of pollen transfer dynamics associated with heterostyly, a floral syndrome that depends on precise pollen transfer. Our model shows that precise pollen transfer can cause sexual selection leading to divergence in reproductive-organ positions between populations served by different pollinators, pleiotropically causing an increase in reproductive isolation through a "magic trait" mechanism. Furthermore, this increased reproductive isolation facilitates adaptive divergence between the populations in an unlinked, ecologically selected trait. In a different pollination scenario, however, precise pollen transfer causes a decrease in adaptive divergence by promoting asymmetric gene flow. Our results highlight the idea that magic traits are not "magic" in isolation; in particular, the effect size of magic traits in speciation depends on the external environment, and also on other traits that modify the strength of the magic trait's influence on non-random mating. Overall, we show that the evolutionary consequences of pollen transfer dynamics can depend strongly on the available pollinator fauna and on the morphological fit between flowers and pollinators. Furthermore, our results illustrate the potential importance of even weak reproductive isolating barriers in facilitating adaptive divergence.

Motorization of a surgical microscope for intra-operative navigation and intuitive control.

PubMed

Finke, M; Schweikard, A

2010-09-01

During surgical procedures, various medical systems, e.g. microscope or C-arm, are used. Their precise and repeatable manual positioning can be very cumbersome and interrupts the surgeon's work flow. Robotized systems can assist the surgeon but they require suitable kinematics and control. However, positioning must be fast, flexible and intuitive. We describe a fully motorized surgical microscope. Hardware components as well as implemented applications are specified. The kinematic equations are described and a novel control concept is proposed. Our microscope combines fast manual handling with accurate, automatic positioning. Intuitive control is provided by a small remote control mounted to one of the surgical instruments. Positioning accuracy and repeatability are < 1 mm and vibrations caused by automatic movements fade away in about 1 s. The robotic system assists the surgeon, so that he can position the microscope precisely and repeatedly without interrupting the clinical workflow. The combination of manual und automatic control guarantees fast and flexible positioning during surgical procedures. Copyright 2010 John Wiley & Sons, Ltd.

Positioning stability improvement with inter-system biases on multi-GNSS PPP

NASA Astrophysics Data System (ADS)

Choi, Byung-Kyu; Yoon, Hasu

2018-07-01

The availability of multiple signals from different Global Navigation Satellite System (GNSS) constellations provides opportunities for improving positioning accuracy and initial convergence time. With dual-frequency observations from the four constellations (GPS, GLONASS, Galileo, and BeiDou), it is possible to investigate combined GNSS precise point positioning (PPP) accuracy and stability. The differences between GNSS systems result in inter-system biases (ISBs). We consider several ISB values such as GPS-GLONASS, GPS-Galileo, and GPS-BeiDou. These biases are compliant with key parameters defined in the multi-GNSS PPP processing. In this study, we present a unified PPP method that sets ISB values as fixed or constant. A comprehensive analysis that includes satellite visibility, position dilution of precision, position accuracy is performed to evaluate a unified PPP method with constrained cut-off elevation angles. Compared to the conventional PPP solutions, our approach shows more stable positioning at a constrained cut-off elevation angle of 50 degrees.

GPS inferred geocentric reference frame for satellite positioning and navigation

NASA Technical Reports Server (NTRS)

Malla, Rajendra P.; Wu, Sien-Chong

1989-01-01

Accurate geocentric three-dimensional positioning is of great importance for various geodetic and oceanographic applications. While relative positioning accuracy of a few centimeters has become a reality using Very Long Baseline Interferometry (VLBI), the uncertainty in the offset of the adopted coordinate system origin from the geocenter is still believed to be of the order of one meter. Satellite Laser Ranging (SLR) is capable of determining this offset to better than 10 cm, though, because of the limited number of satellites, this requires a long arc of data. The Global Positioning System (GPS) measurements provide a powerful alternative for an accurate determination of this origin offset in relatively short period of time. Two strategies are discussed, the first utilizes the precise relative positions predetermined by VLBI, whereas the second establishes a reference frame by holding only one of the tracking sites longitude fixed. Covariance analysis studies indicate that geocentric positioning to an accuracy of a few centimeters can be achieved with just one day of precise GPS pseudorange and carrier phase data.

Processes, Products, and Measures of Memory Organization.

ERIC Educational Resources Information Center

Pellegrino, James W.; Ingram, Albert L.

Some of the issues associated with the lack of a precisely stated theory of memory organization are considered. The first section provides an overview of the concept of organization. Emphasis is on problems associated with the definition of organization, especially the distinction between organization as a process and as the product of a process.…

Evaluation of neural network modeing to calculate well-watered leaf temperature of wine grape

USDA-ARS?s Scientific Manuscript database

Mild to moderate water stress is desirable in wine grape for controlling vine vigor and optimizing fruit yield and quality, but precision irrigation management is hindered by the lack of a reliable method to easily quantify and monitor vine water status. The crop water stress index (CWSI) that effec...

No Homeless Child Left behind

ERIC Educational Resources Information Center

Saxberg, David

2011-01-01

Although it is difficult to determine the precise number of homeless children, the National Coalition for the Homeless reports that there are more than 1.3 million children lacking a permanent residence on any given night. Further, 39 percent of the homeless population was comprised of children under the age of 18 in July 2009, the most recent…

Microscale acceleration history discriminators

DOEpatents

Polosky, Marc A.; Plummer, David W.

2002-01-01

A new class of micromechanical acceleration history discriminators is claimed. These discriminators allow the precise differentiation of a wide range of acceleration-time histories, thereby allowing adaptive events to be triggered in response to the severity (or lack thereof) of an external environment. Such devices have applications in airbag activation, and other safety and surety applications.

The Challenges and Possibilities of a Narrative Learning Approach in the Finnish Early Childhood Education System

ERIC Educational Resources Information Center

Hakkarainen, Pentti

2008-01-01

Finnish curriculum guidelines for early education emphasise play and creative activities as significant factors in healthy child development. Constructivist theory loosely frames the guidelines, but the recommended approach lacks precise developmental goals. Since 1996, we have carried out a narrative learning project with vertically integrated…

The Use of Foreign Languages in Tourism: Research Needs.

ERIC Educational Resources Information Center

Watts, Noel

1994-01-01

Examines the research needs relative to the use of foreign languages in tourism activities in Australia and New Zealand. Findings indicate a lack of precise information on the ways in which the tourism industry in these countries provides appropriate language assistance to non-English speaking inbound visitors. Suggestions for future research are…

From implant planning to surgical execution: an integrated approach for surgery in oral implantology.

PubMed

Chiarelli, Tommaso; Franchini, Federico; Lamma, Achille; Lamma, Evelina; Sansoni, Tommaso

2012-03-01

Using oral implantology software and transferring the preoperative planning into a stereolithographic model, prosthodontists can produce the related surgical guide. This procedure has some disadvantages: bone-supported stent invasiveness, lack of references due to scattering and non-negligible stereolithography cost. An alternative solution is presented that provides an ideal surgical stent (not invasive, precise, and cheap) as a result. This work focuses on the third phase of a fully 3D approach to oral implant planning, that starts by CT scanning a patient who wears a markers-equipped radiological stent, continues exploiting built-on-purpose preoperative planning software, and finishes producing the ideal surgical template. A 5-axes bur-equipped robot has been designed able to reproduce the milling vectors planned by the software. Software-robot interfacing has been achieved properly matching the stent reference frame and the software and robot coordinate systems. Invasiveness has been avoided achieving the surgical stent from the mucosa-supported radiological mask wax-up. Scattering is ignored because of the surgical stent independency from the bone structure radiography. Production cost has been strongly reduced by avoiding the stereolithographic model. Finally, software-robot interfacing precision has been validated comparing digitally a multi-marker base and its planning transfer. Average position and orientation errors (respectively 0.283 mm ± 0.073 mm and 1.798° ± 0.496°) were significantly better than those achieved using methods based on stereolithography (respectively, 1.45 mm ± 1.42 mm and 7.25° ± 2.67°, with a general best maximum translation discrepancy of about 1.1 mm). This paper describes the last step of a fully 3D approach in which implant planning can be done in a 3D environment, and the correct position, orientation and depth of the planned implants are easily computed and transferred to the surgical phase. Copyright © 2011 John Wiley & Sons, Ltd.

Precise orbit determination of Multi-GNSS constellation including GPS GLONASS BDS and GALIEO

NASA Astrophysics Data System (ADS)

Dai, Xiaolei

2014-05-01

In addition to the existing American global positioning system (GPS) and the Russian global navigation satellite system (GLONASS), the new generation of GNSS is emerging and developing, such as the Chinese BeiDou satellite navigation system (BDS) and the European GALILEO system. Multi-constellation is expected to contribute to more accurate and reliable positioning and navigation service. However, the application of multi-constellation challenges the traditional precise orbit determination (POD) strategy that was designed usually for single constellation. In this contribution, we exploit a more rigorous multi-constellation POD strategy for the ongoing IGS multi-GNSS experiment (MGEX) where the common parameters are identical for each system, and the frequency- and system-specified parameters are employed to account for the inter-frequency and inter-system biases. Since the authorized BDS attitude model is not yet released, different BDS attitude model are implemented and their impact on orbit accuracy are studied. The proposed POD strategy was implemented in the PANDA (Position and Navigation Data Analyst) software and can process observations from GPS, GLONASS, BDS and GALILEO together. The strategy is evaluated with the multi-constellation observations from about 90 MGEX stations and BDS observations from the BeiDou experimental tracking network (BETN) of Wuhan University (WHU). Of all the MGEX stations, 28 stations record BDS observation, and about 80 stations record GALILEO observations. All these data were processed together in our software, resulting in the multi-constellation POD solutions. We assessed the orbit accuracy for GPS and GLONASS by comparing our solutions with the IGS final orbit, and for BDS and GALILEO by overlapping our daily orbit solution. The stability of inter-frequency bias of GLONASS and inter-system biases w.r.t. GPS for GLONASS, BDS and GALILEO were investigated. At last, we carried out precise point positioning (PPP) using the multi-constellation POD orbit and clock products, and analyzed the contribution of these POD products to PPP. Keywords: Multi-GNSS, Precise Orbit Determination, Inter-frequency bias, Inter-system bias, Precise Point Positioning

Improving multi-GNSS ultra-rapid orbit determination for real-time precise point positioning

NASA Astrophysics Data System (ADS)

Li, Xingxing; Chen, Xinghan; Ge, Maorong; Schuh, Harald

2018-03-01

Currently, with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSS), the real-time positioning and navigation are undergoing dramatic changes with potential for a better performance. To provide more precise and reliable ultra-rapid orbits is critical for multi-GNSS real-time positioning, especially for the three merging constellations Beidou, Galileo and QZSS which are still under construction. In this contribution, we present a five-system precise orbit determination (POD) strategy to fully exploit the GPS + GLONASS + BDS + Galileo + QZSS observations from CDDIS + IGN + BKG archives for the realization of hourly five-constellation ultra-rapid orbit update. After adopting the optimized 2-day POD solution (updated every hour), the predicted orbit accuracy can be obviously improved for all the five satellite systems in comparison to the conventional 1-day POD solution (updated every 3 h). The orbit accuracy for the BDS IGSO satellites can be improved by about 80, 45 and 50% in the radial, cross and along directions, respectively, while the corresponding accuracy improvement for the BDS MEO satellites reaches about 50, 20 and 50% in the three directions, respectively. Furthermore, the multi-GNSS real-time precise point positioning (PPP) ambiguity resolution has been performed by using the improved precise satellite orbits. Numerous results indicate that combined GPS + BDS + GLONASS + Galileo (GCRE) kinematic PPP ambiguity resolution (AR) solutions can achieve the shortest time to first fix (TTFF) and highest positioning accuracy in all coordinate components. With the addition of the BDS, GLONASS and Galileo observations to the GPS-only processing, the GCRE PPP AR solution achieves the shortest average TTFF of 11 min with 7{°} cutoff elevation, while the TTFF of GPS-only, GR, GE and GC PPP AR solution is 28, 15, 20 and 17 min, respectively. As the cutoff elevation increases, the reliability and accuracy of GPS-only PPP AR solutions decrease dramatically, but there is no evident decrease for the accuracy of GCRE fixed solutions which can still achieve an accuracy of a few centimeters in the east and north components.

Piping inspection instrument carriage with precise and repeatable position control and location determination

DOEpatents

Hapstack, M.; Talarek, T.R.; Zollinger, W.T.; Heckendorn, F.M. II; Park, L.R.

1994-02-15

An instrument carriage for inspection of piping comprises front and rear leg assemblies for engaging the interior of the piping and supporting and centering the carriage therein, and an instrumentation arm carried by a shaft system running from the front to rear leg assemblies. The shaft system has a screw shaft for moving the arm axially and a spline gear for moving the arm azimuthally. The arm has a pair of air cylinders that raise and lower a plate in the radial direction. On the plate are probes including an eddy current probe and an ultrasonic testing probe. The ultrasonic testing probe is capable of spinning 360[degree] about its axis. The instrument carriage uses servo motors and pressurized air cylinders for precise actuation of instrument components and precise, repeatable actuation of position control mechanisms. 8 figures.

Piping inspection instrument carriage with precise and repeatable position control and location determination

DOEpatents

Hapstack, Mark; Talarek, Ted R.; Zollinger, W. Thor; Heckendorn, II, Frank M.; Park, Larry R.

1994-01-01

An instrument carriage for inspection of piping comprises front and rear leg assemblies for engaging the interior of the piping and supporting and centering the carriage therein, and an instrumentation arm carried by a shaft system running from the front to rear leg assemblies. The shaft system has a screw shaft for moving the arm axially and a spline gear for moving the arm azimuthally. The arm has a pair of air cylinders that raise and lower a plate in the radial direction. On the plate are probes including an eddy current probe and an ultrasonic testing probe. The ultrasonic testing probe is capable of spinning 360.degree. about its axis. The instrument carriage uses servo motors and pressurized air cylinders for precise actuation of instrument components and precise, repeatable actuation of position control mechanisms.

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

NASA Technical Reports Server (NTRS)

Sydnor, Richard L. (Editor)

1996-01-01

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

Improving precise positioning of surgical robotic instruments by a three-side-view presentation system on telesurgery.

PubMed

Hori, Kenta; Kuroda, Tomohiro; Oyama, Hiroshi; Ozaki, Yasuhiko; Nakamura, Takehiko; Takahashi, Takashi

2005-12-01

For faultless collaboration among the surgeon, surgical staffs, and surgical robots in telesurgery, communication must include environmental information of the remote operating room, such as behavior of robots and staffs, vital information of a patient, named supporting information, in addition to view of surgical field. "Surgical Cockpit System, " which is a telesurgery support system that has been developed by the authors, is mainly focused on supporting information exchange between remote sites. Live video presentation is important technology for Surgical Cockpit System. Visualization method to give precise location/posture of surgical instruments is indispensable for accurate control and faultless operation. In this paper, the authors propose three-side-view presentation method for precise location/posture control of surgical instruments in telesurgery. The experimental results show that the proposed method improved accurate positioning of a telemanipulator.

Robotic Surgery

NASA Technical Reports Server (NTRS)

2000-01-01

The Automated Endoscopic System for Optimal Positioning, or AESOP, was developed by Computer Motion, Inc. under a SBIR contract from the Jet Propulsion Lab. AESOP is a robotic endoscopic positioning system used to control the motion of a camera during endoscopic surgery. The camera, which is mounted at the end of a robotic arm, previously had to be held in place by the surgical staff. With AESOP the robotic arm can make more precise and consistent movements. AESOP is also voice controlled by the surgeon. It is hoped that this technology can be used in space repair missions which require precision beyond human dexterity. A new generation of the same technology entitled the ZEUS Robotic Surgical System can make endoscopic procedures even more successful. ZEUS allows the surgeon control various instruments in its robotic arms, allowing for the precision the procedure requires.

All-optical patterning of Au nanoparticles on surfaces using optical traps.

PubMed

Guffey, Mason J; Scherer, Norbert F

2010-11-10

The fabrication of nanoscale devices would be greatly enhanced by "nanomanipulators" that can position single and few objects rapidly with nanometer precision and without mechanical damage. Here, we demonstrate the feasibility and precision of an optical laser tweezer, or optical trap, approach to place single gold (Au) nanoparticles on surfaces with high precision (approximately 100 nm standard deviation). The error in the deposition process is rather small but is determined to be larger than the thermal fluctuations of single nanoparticles within the optical trap. Furthermore, areas of tens of square micrometers could be patterned in a matter of minutes. Since the method does not rely on lithography, scanning probes or a specialized surface, it is versatile and compatible with a variety of systems. We discuss active feedback methods to improve positioning accuracy and the potential for multiplexing and automation.

Assessment Study of Using Online (CSRS) GPS-PPP Service for Mapping Applications in Egypt

NASA Astrophysics Data System (ADS)

Abd-Elazeem, Mohamed; Farah, Ashraf; Farrag, Farrag

2011-09-01

Many applications in navigation, land surveying, land title definitions and mapping have been made simpler and more precise due to accessibility of Global Positioning System (GPS) data, and thus the demand for using advanced GPS techniques in surveying applications has become essential. The differential technique was the only source of accurate positioning for many years, and remained in use despite of its cost. The precise point positioning (PPP) technique is a viable alternative to the differential positioning method in which a user with a single receiver can attain positioning accuracy at the centimeter or decimeter scale. In recent years, many organizations introduced online (GPS-PPP) processing services capable of determining accurate geocentric positions using GPS observations. These services provide the user with receiver coordinates in free and unlimited access formats via the internet. This paper investigates the accuracy of the Canadian Spatial Reference System (CSRS) Precise Point Positioning (PPP) (CSRS-PPP) service supervised by the Geodetic Survey Division (GSD), Canada. Single frequency static GPS observations have been collected at three points covering time spans of 60, 90 and 120 minutes. These three observed sites form baselines of 1.6, 7, and 10 km, respectively. In order to assess the CSRS-PPP accuracy, the discrepancies between the CSRS-PPP estimates and the regular differential GPS solutions were computed. The obtained results illustrate that the PPP produces a horizontal error at the scale of a few decimeters; this is accurate enough to serve many mapping applications in developing countries with a savings in both cost and experienced labor.

Design of a Single-Cell Positioning Controller Using Electroosmotic Flow and Image Processing

PubMed Central

Ay, Chyung; Young, Chao-Wang; Chen, Jhong-Yin

2013-01-01

The objective of the current research was not only to provide a fast and automatic positioning platform for single cells, but also improved biomolecular manipulation techniques. In this study, an automatic platform for cell positioning using electroosmotic flow and image processing technology was designed. The platform was developed using a PCI image acquisition interface card for capturing images from a microscope and then transferring them to a computer using human-machine interface software. This software was designed by the Laboratory Virtual Instrument Engineering Workbench, a graphical language for finding cell positions and viewing the driving trace, and the fuzzy logic method for controlling the voltage or time of an electric field. After experiments on real human leukemic cells (U-937), the success of the cell positioning rate achieved by controlling the voltage factor reaches 100% within 5 s. A greater precision is obtained when controlling the time factor, whereby the success rate reaches 100% within 28 s. Advantages in both high speed and high precision are attained if these two voltage and time control methods are combined. The control speed with the combined method is about 5.18 times greater than that achieved by the time method, and the control precision with the combined method is more than five times greater than that achieved by the voltage method. PMID:23698272

A New Method for Single-Epoch Ambiguity Resolution with Indoor Pseudolite Positioning.

PubMed

Li, Xin; Zhang, Peng; Guo, Jiming; Wang, Jinling; Qiu, Weining

2017-04-21

Ambiguity resolution (AR) is crucial for high-precision indoor pseudolite positioning. Due to the existing characteristics of the pseudolite positioning system, such as the geometry structure of the stationary pseudolite which is consistently invariant, the indoor signal is easy to interrupt and the first order linear truncation error cannot be ignored, and a new AR method based on the idea of the ambiguity function method (AFM) is proposed in this paper. The proposed method is a single-epoch and nonlinear method that is especially well-suited for indoor pseudolite positioning. Considering the very low computational efficiency of conventional AFM, we adopt an improved particle swarm optimization (IPSO) algorithm to search for the best solution in the coordinate domain, and variances of a least squares adjustment is conducted to ensure the reliability of the solving ambiguity. Several experiments, including static and kinematic tests, are conducted to verify the validity of the proposed AR method. Numerical results show that the IPSO significantly improved the computational efficiency of AFM and has a more elaborate search ability compared to the conventional grid searching method. For the indoor pseudolite system, which had an initial approximate coordinate precision better than 0.2 m, the AFM exhibited good performances in both static and kinematic tests. With the corrected ambiguity gained from our proposed method, indoor pseudolite positioning can achieve centimeter-level precision using a low-cost single-frequency software receiver.

Tightly Coupled Integration of Ionosphere-Constrained Precise Point Positioning and Inertial Navigation Systems

PubMed Central

Gao, Zhouzheng; Zhang, Hongping; Ge, Maorong; Niu, Xiaoji; Shen, Wenbin; Wickert, Jens; Schuh, Harald

2015-01-01

The continuity and reliability of precise GNSS positioning can be seriously limited by severe user observation environments. The Inertial Navigation System (INS) can overcome such drawbacks, but its performance is clearly restricted by INS sensor errors over time. Accordingly, the tightly coupled integration of GPS and INS can overcome the disadvantages of each individual system and together form a new navigation system with a higher accuracy, reliability and availability. Recently, ionosphere-constrained (IC) precise point positioning (PPP) utilizing raw GPS observations was proven able to improve both the convergence and positioning accuracy of the conventional PPP using ionosphere-free combined observations (LC-PPP). In this paper, a new mode of tightly coupled integration, in which the IC-PPP instead of LC-PPP is employed, is implemented to further improve the performance of the coupled system. We present the detailed mathematical model and the related algorithm of the new integration of IC-PPP and INS. To evaluate the performance of the new tightly coupled integration, data of both airborne and vehicle experiments with a geodetic GPS receiver and tactical grade inertial measurement unit are processed and the results are analyzed. The statistics show that the new approach can further improve the positioning accuracy compared with both IC-PPP and the tightly coupled integration of the conventional PPP and INS. PMID:25763647

Age-Related Decline of Wrist Position Sense and its Relationship to Specific Physical Training

PubMed Central

Van de Winckel, Ann; Tseng, Yu-Ting; Chantigian, Daniel; Lorant, Kaitlyn; Zarandi, Zinat; Buchanan, Jeffrey; Zeffiro, Thomas A.; Larson, Mia; Olson-Kellogg, Becky; Konczak, Jürgen; Keller-Ross, Manda L.

2017-01-01

Perception of limb and body positions is known as proprioception. Sensory feedback, especially from proprioceptive receptors, is essential for motor control. Aging is associated with a decline in position sense at proximal joints, but there is inconclusive evidence of distal joints being equally affected by aging. In addition, there is initial evidence that physical activity attenuates age-related decline in proprioception. Our objectives were, first, to establish wrist proprioceptive acuity in a large group of seniors and compare their perception to young adults, and second, to determine if specific types of training or regular physical activity are associated with preserved wrist proprioception. We recruited community-dwelling seniors (n = 107, mean age, 70 ± 5 years, range, 65–84 years) without cognitive decline (Mini Mental State Examination-brief version ≥13/16) and young adult students (n = 51, mean age, 20 ± 1 years, range, 19–26 years). Participants performed contralateral and ipsilateral wrist position sense matching tasks with a bimanual wrist manipulandum to a 15° flexion reference position. Systematic error or proprioceptive bias was computed as the mean difference between matched and reference position. The respective standard deviation over five trials constituted a measure of random error or proprioceptive precision. Current levels of physical activity and previous sport, musical, or dance training were obtained through a questionnaire. We employed longitudinal mixed effects linear models to calculate the effects of trial number, sex, type of matching task and age on wrist proprioceptive bias and precision. The main results were that relative proprioceptive bias was greater in older when compared to young adults (mean difference: 36% ipsilateral, 88% contralateral, p < 0.01). Proprioceptive precision for contralateral but not for ipsilateral matching was smaller in older than in young adults (mean difference: 38% contralateral, p < 0.01). Longer years of dance training were associated with smaller bias during ipsilateral matching (p < 0.01). Other types of training or physical activity levels did not affect bias or precision. Our findings demonstrate that aging is associated with a decline in proprioceptive bias in distal arm joints, but age does not negatively affect proprioceptive precision. Further, specific types of long-term dance related training may attenuate age-related decline in proprioceptive bias. PMID:29209188

Age-Related Decline of Wrist Position Sense and its Relationship to Specific Physical Training.

PubMed

Van de Winckel, Ann; Tseng, Yu-Ting; Chantigian, Daniel; Lorant, Kaitlyn; Zarandi, Zinat; Buchanan, Jeffrey; Zeffiro, Thomas A; Larson, Mia; Olson-Kellogg, Becky; Konczak, Jürgen; Keller-Ross, Manda L

2017-01-01

Perception of limb and body positions is known as proprioception. Sensory feedback, especially from proprioceptive receptors, is essential for motor control. Aging is associated with a decline in position sense at proximal joints, but there is inconclusive evidence of distal joints being equally affected by aging. In addition, there is initial evidence that physical activity attenuates age-related decline in proprioception. Our objectives were, first, to establish wrist proprioceptive acuity in a large group of seniors and compare their perception to young adults, and second, to determine if specific types of training or regular physical activity are associated with preserved wrist proprioception. We recruited community-dwelling seniors ( n = 107, mean age, 70 ± 5 years, range, 65-84 years) without cognitive decline (Mini Mental State Examination-brief version ≥13/16) and young adult students ( n = 51, mean age, 20 ± 1 years, range, 19-26 years). Participants performed contralateral and ipsilateral wrist position sense matching tasks with a bimanual wrist manipulandum to a 15° flexion reference position. Systematic error or proprioceptive bias was computed as the mean difference between matched and reference position. The respective standard deviation over five trials constituted a measure of random error or proprioceptive precision . Current levels of physical activity and previous sport, musical, or dance training were obtained through a questionnaire. We employed longitudinal mixed effects linear models to calculate the effects of trial number, sex, type of matching task and age on wrist proprioceptive bias and precision. The main results were that relative proprioceptive bias was greater in older when compared to young adults (mean difference: 36% ipsilateral, 88% contralateral, p < 0.01). Proprioceptive precision for contralateral but not for ipsilateral matching was smaller in older than in young adults (mean difference: 38% contralateral, p < 0.01). Longer years of dance training were associated with smaller bias during ipsilateral matching ( p < 0.01). Other types of training or physical activity levels did not affect bias or precision. Our findings demonstrate that aging is associated with a decline in proprioceptive bias in distal arm joints, but age does not negatively affect proprioceptive precision. Further, specific types of long-term dance related training may attenuate age-related decline in proprioceptive bias.

Evaluation of the EGNOS service for topographic profiling in field geosciences

NASA Astrophysics Data System (ADS)

Kromuszczyńska, Olga; Mège, Daniel; Castaldo, Luigi; Gurgurewicz, Joanna; Makowska, Magdalena; Dębniak, Krzysztof; Jelínek, Róbert

2016-09-01

Consumer grade Global Positioning System (GPS) receivers are commonly used as a tool for data collection in many fields, including geosciences. One of the methods for improving the GPS signal is provided by the Wide Area Differential GPS (WADGPS), which uses geostationary satellites to correct errors affecting the signal in real time. This study presents results of three experiments aiming at determining whether the precision of field measurements made by such a receiver (Garmin GPSMAP 62s) operating in either the non-differential and the WADGPS differential mode is suitable for characterizing geomorphological objects or landforms. It assumes in a typical field work situation, when time cannot be devoted in the field to long periods of stationary GPS measurements and the precision of topographic profile is at least as important as, if not more than, positioning of individual points. The results show that with maintaining some rules, the expected precision may meet the nominal precision. The repeatability (coherence) of topographic profiles conducted at low speed (0.5 m s- 1) in mountain terrain is good, and vertical precision is improved in the WADGPS mode. Horizontal precision is equivalent in both modes. The GPS receiver should be operating at least 30 min prior to measuring and should not be turned off between measurements that the user like to compare. If the GPS receiver needs to be reset between profiles to be compared, the measurement precision is higher in the non-differential GPS mode. Following these rules may result in improvement of measurement quality by 20% to 80%.

Supersonic Retropulsion Surface Preparation of Carbon Fiber Reinforced Epoxy Composites for Adhesive Bonding

NASA Technical Reports Server (NTRS)

Palmieri, Frank L.; Belcher, Marcus A.; Wohl, Christopher J.; Blohowiak, Kay Y.; Connell, John W.

2013-01-01

Surface preparation is widely recognized as a key step to producing robust and predictable bonds in a precise and reproducible manner. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, can lack precision and reproducibility, which can lead to variation in surface properties and subsequent bonding performance. The use of a laser to ablate composite surface resin can provide an efficient, precise, and reproducible means of preparing composite surfaces for adhesive bonding. Advantages include elimination of physical waste (i.e., grit media and sacrificial peel ply layers that ultimately require disposal), reduction in process variability due to increased precision (e.g. increased reproducibility), and automation of surface preparation, all of which improve reliability and process control. This paper describes a Nd:YAG laser surface preparation technique for composite substrates and the mechanical performance and failure modes of bonded laminates thus prepared. Additionally, bonded specimens were aged in a hot, wet environment for approximately one year and subsequently mechanically tested. The results of a one year hygrothermal aging study will be presented.

Patient-derived orthotopic xenograft models for cancer of unknown primary precisely distinguish chemotherapy, and tumor-targeting S. typhimurium A1-R is superior to first-line chemotherapy.

PubMed

Miyake, Kentaro; Kiyuna, Tasuku; Miyake, Masuyo; Kawaguchi, Kei; Yoon, Sang Nam; Zhang, Zhiying; Igarashi, Kentaro; Razmjooei, Sahar; Wangsiricharoen, Sintawat; Murakami, Takashi; Li, Yunfeng; Nelson, Scott D; Russell, Tara A; Singh, Arun S; Hiroshima, Yukihiko; Momiyama, Masashi; Matsuyama, Ryusei; Chishima, Takashi; Singh, Shree Ram; Endo, Itaru; Eilber, Fritz C; Hoffman, Robert M

2018-01-01

Cancer of unknown primary (CUP) is a recalcitrant disease with poor prognosis because it lacks standard first-line therapy. CUP consists of diverse malignancy groups, making personalized precision therapy essential. The present study aimed to identify an effective therapy for a CUP patient using a patient-derived orthotopic xenograft (PDOX) model. This paper reports the usefulness of the PDOX model to precisely identify effective and ineffective chemotherapy and to compare the efficacy of S. typhimurium A1-R with first-line chemotherapy using the CUP PDOX model. The present study is the first to use a CUP PDOX model, which was able to precisely distinguish the chemotherapeutic course. We found that a carboplatinum (CAR)-based regimen was effective for this CUP patient. We also demonstrated that S. typhimurium A1-R was more effective against the CUP tumor than first-line chemotherapy. Our results indicate that S. typhimurium A1-R has clinical potential for CUP, a resistant disease that requires effective therapy.

Nanoscale tailor-made membranes for precise and rapid molecular sieve separation.

PubMed

Wang, Jing; Zhu, Junyong; Zhang, Yatao; Liu, Jindun; Van der Bruggen, Bart

2017-03-02

The precise and rapid separation of different molecules from aqueous, organic solutions and gas mixtures is critical to many technologies in the context of resource-saving and sustainable development. The strength of membrane-based technologies is well recognized and they are extensively applied as cost-effective, highly efficient separation techniques. Currently, empirical-based approaches, lacking an accurate nanoscale control, are used to prepare the most advanced membranes. In contrast, nanoscale control renders the membrane molecular specificity (sub-2 nm) necessary for efficient and rapid molecular separation. Therefore, as a growing trend in membrane technology, the field of nanoscale tailor-made membranes is highlighted in this review. An in-depth analysis of the latest advances in tailor-made membranes for precise and rapid molecule sieving is given, along with an outlook to future perspectives of such membranes. Special attention is paid to the established processing strategies, as well as the application of molecular dynamics (MD) simulation in nanoporous membrane design. This review will provide useful guidelines for future research in the development of nanoscale tailor-made membranes with a precise and rapid molecular sieve separation property.

A simple customized surgical guide for orthodontic miniplates with tube.

PubMed

Paek, Janghyun; Su, Ming-Jeaun; Kwon, Soon-Yong; Kim, Seong-Hun; Chung, Kyu-Rhim; Nelson, Gerald

2012-09-01

This article reports the use of a customized surgical guide for simple and precise C-tube plate placement with minimized incision. Patients who were planning to have orthodontic miniplate treatment because of narrow interradicular space were recruited for this study. A combined silicone and stainless steel wire surgical guide for the C-tube was fabricated on the cast model. The taller wire of the positioning guide is used to accurately start the incision. The incision guide-wire position is verified by placing the miniplate on the coronal horizontal wire to confirm that the incision will coordinate with the screw holes. Because the miniplate is firmly held in place, there is no risk of the miniplate anchoring screws (diameter, 1.5 mm; length, 4 mm) sliding on the bone surface during placement with a manual hand driver. The surgical guide was placed on the clinical site, and it allowed precise placement of the miniplate with minimum incision and preventing from slippage or path-of-insertion angulation errors that might interfere with accurate placement. Customized surgical guide enables precise planning for miniplate positions in anatomically complex sites.

Hybrid Orientation Based Human Limbs Motion Tracking Method

PubMed Central

Glonek, Grzegorz; Wojciechowski, Adam

2017-01-01

One of the key technologies that lays behind the human–machine interaction and human motion diagnosis is the limbs motion tracking. To make the limbs tracking efficient, it must be able to estimate a precise and unambiguous position of each tracked human joint and resulting body part pose. In recent years, body pose estimation became very popular and broadly available for home users because of easy access to cheap tracking devices. Their robustness can be improved by different tracking modes data fusion. The paper defines the novel approach—orientation based data fusion—instead of dominating in literature position based approach, for two classes of tracking devices: depth sensors (i.e., Microsoft Kinect) and inertial measurement units (IMU). The detailed analysis of their working characteristics allowed to elaborate a new method that let fuse more precisely limbs orientation data from both devices and compensates their imprecisions. The paper presents the series of performed experiments that verified the method’s accuracy. This novel approach allowed to outperform the precision of position-based joints tracking, the methods dominating in the literature, of up to 18%. PMID:29232832

Design and Analysis of a Compact Precision Positioning Platform Integrating Strain Gauges and the Piezoactuator

PubMed Central

Huang, Hu; Zhao, Hongwei; Yang, Zhaojun; Fan, Zunqiang; Wan, Shunguang; Shi, Chengli; Ma, Zhichao

2012-01-01

Miniaturization precision positioning platforms are needed for in situ nanomechanical test applications. This paper proposes a compact precision positioning platform integrating strain gauges and the piezoactuator. Effects of geometric parameters of two parallel plates on Von Mises stress distribution as well as static and dynamic characteristics of the platform were studied by the finite element method. Results of the calibration experiment indicate that the strain gauge sensor has good linearity and its sensitivity is about 0.0468 mV/μm. A closed-loop control system was established to solve the problem of nonlinearity of the platform. Experimental results demonstrate that for the displacement control process, both the displacement increasing portion and the decreasing portion have good linearity, verifying that the control system is available. The developed platform has a compact structure but can realize displacement measurement with the embedded strain gauges, which is useful for the closed-loop control and structure miniaturization of piezo devices. It has potential applications in nanoindentation and nanoscratch tests, especially in the field of in situ nanomechanical testing which requires compact structures. PMID:23012566

Feedforward hysteresis compensation in trajectory control of piezoelectrically-driven nanostagers

NASA Astrophysics Data System (ADS)

Bashash, Saeid; Jalili, Nader

2006-03-01

Complex structural nonlinearities of piezoelectric materials drastically degrade their performance in variety of micro- and nano-positioning applications. From the precision positioning and control perspective, the multi-path time-history dependent hysteresis phenomenon is the most concerned nonlinearity in piezoelectric actuators to be analyzed. To realize the underlying physics of this phenomenon and to develop an efficient compensation strategy, the intelligent properties of hysteresis with the effects of non-local memories are discussed. Through performing a set of experiments on a piezoelectrically-driven nanostager with high resolution capacitive position sensor, it is shown that for the precise prediction of hysteresis path, certain memory units are required to store the previous hysteresis trajectory data. Based on the experimental observations, a constitutive memory-based mathematical modeling framework is developed and trained for the precise prediction of hysteresis path for arbitrarily assigned input profiles. Using the inverse hysteresis model, a feedforward control strategy is then developed and implemented on the nanostager to compensate for the system everpresent nonlinearity. Experimental results demonstrate that the controller remarkably eliminates the nonlinear effect if memory units are sufficiently chosen for the inverse model.

A video-based speed estimation technique for localizing the wireless capsule endoscope inside gastrointestinal tract.

PubMed

Bao, Guanqun; Mi, Liang; Geng, Yishuang; Zhou, Mingda; Pahlavan, Kaveh

2014-01-01

Wireless Capsule Endoscopy (WCE) is progressively emerging as one of the most popular non-invasive imaging tools for gastrointestinal (GI) tract inspection. As a critical component of capsule endoscopic examination, physicians need to know the precise position of the endoscopic capsule in order to identify the position of intestinal disease. For the WCE, the position of the capsule is defined as the linear distance it is away from certain fixed anatomical landmarks. In order to measure the distance the capsule has traveled, a precise knowledge of how fast the capsule moves is urgently needed. In this paper, we present a novel computer vision based speed estimation technique that is able to extract the speed of the endoscopic capsule by analyzing the displacements between consecutive frames. The proposed approach is validated using a virtual testbed as well as the real endoscopic images. Results show that the proposed method is able to precisely estimate the speed of the endoscopic capsule with 93% accuracy on average, which enhances the localization accuracy of the WCE to less than 2.49 cm.

Precision Farming and Precision Pest Management: The Power of New Crop Production Technologies

PubMed Central

Strickland, R. Mack; Ess, Daniel R.; Parsons, Samuel D.

1998-01-01

The use of new technologies including Geographic Information Systems (GIS), the Global Positioning System (GPS), Variable Rate Technology (VRT), and Remote Sensing (RS) is gaining acceptance in the present high-technology, precision agricultural industry. GIS provides the ability to link multiple data values for the same geo-referenced location, and provides the user with a graphical visualization of such data. When GIS is coupled with GPS and RS, management decisions can be applied in a more precise "micro-managed" manner by using VRT techniques. Such technology holds the potential to reduce agricultural crop production costs as well as crop and environmental damage. PMID:19274236

High precision localization of intracerebral hemorrhage based on 3D MPR on head CT images

NASA Astrophysics Data System (ADS)

Sun, Jianyong; Hou, Xiaoshuai; Sun, Shujie; Zhang, Jianguo

2017-03-01

The key step for minimally invasive intracerebral hemorrhage surgery is precisely positioning the hematoma location in the brain before and during the hematoma surgery, which can significantly improves the success rate of puncture hematoma. We designed a 3D computerized surgical plan (CSP) workstation precisely to locate brain hematoma based on Multi-Planar Reconstruction (MPR) visualization technique. We used ten patients' CT/MR studies to verify our designed CSP intracerebral hemorrhage localization method. With the doctor's assessment and comparing with the results of manual measurements, the output of CSP WS for hematoma surgery is more precise and reliable than manual procedure.

The United States Naval Observatory (USNO) - Naval Oceanography Portal

Science.gov Websites

section Advanced Search... Sections Home Time Earth Orientation Astronomy Meteorology Oceanography Ice You Orientation Precise Time James M. Gilliss Library News, Tours & Events About Us Info The United States positions and motion of celestial bodies, motions of the Earth, and precise time. USNO provides tailored

Improving the precision of linear optics measurements based on turn-by-turn beam position monitor data after a pulsed excitation in lepton storage rings

NASA Astrophysics Data System (ADS)

Malina, L.; Coello de Portugal, J.; Persson, T.; Skowroński, P. K.; Tomás, R.; Franchi, A.; Liuzzo, S.

2017-08-01

Beam optics control is of critical importance for machine performance and protection. Nowadays, turn-by-turn (TbT) beam position monitor (BPM) data are increasingly exploited as they allow for fast and simultaneous measurement of various optics quantities. Nevertheless, so far the best documented uncertainty of measured β -functions is of about 10‰ rms. In this paper we compare the β -functions of the ESRF storage ring measured from two different TbT techniques—the N-BPM and the Amplitude methods—with the ones inferred from a measurement of the orbit response matrix (ORM). We show how to improve the precision of TbT techniques by refining the Fourier transform of TbT data with properly chosen excitation amplitude. The precision of the N-BPM method is further improved by refining the phase advance measurement. This represents a step forward compared to standard TbT measurements. First experimental results showing the precision of β -functions pushed down to 4‰ both in TbT and ORM techniques are reported and commented.

Master-slave micromanipulator apparatus

DOEpatents

Morimoto, A.K.; Kozlowski, D.M.; Charles, S.T.; Spalding, J.A.

1999-08-31

An apparatus is disclosed based on precision X-Y stages that are stacked. Attached to arms projecting from each X-Y stage are a set of two axis gimbals. Attached to the gimbals is a rod, which provides motion along the axis of the rod and rotation around its axis. A dual-planar apparatus that provides six degrees of freedom of motion precise to within microns of motion. Precision linear stages along with precision linear motors, encoders, and controls provide a robotics system. The motors can be positioned in a remote location by incorporating a set of bellows on the motors and can be connected through a computer controller that will allow one to be a master and the other one to be a slave. Position information from the master can be used to control the slave. Forces of interaction of the slave with its environment can be reflected back to the motor control of the master to provide a sense of force sensed by the slave. Forces import onto the master by the operator can be fed back into the control of the slave to reduce the forces required to move it. 12 figs.

Master-slave micromanipulator apparatus

DOEpatents

Morimoto, Alan K.; Kozlowski, David M.; Charles, Steven T.; Spalding, James A.

1999-01-01

An apparatus based on precision X-Y stages that are stacked. Attached to arms projecting from each X-Y stage are a set of two axis gimbals. Attached to the gimbals is a rod, which provides motion along the axis of the rod and rotation around its axis. A dual-planar apparatus that provides six degrees of freedom of motion precise to within microns of motion. Precision linear stages along with precision linear motors, encoders, and controls provide a robotics system. The motors can be positioned in a remote location by incorporating a set of bellows on the motors and can be connected through a computer controller that will allow one to be a master and the other one to be a slave. Position information from the master can be used to control the slave. Forces of interaction of the slave with its environment can be reflected back to the motor control of the master to provide a sense of force sensed by the slave. Forces import onto the master by the operator can be fed back into the control of the slave to reduce the forces required to move it.

A rubidium traced white-light etalon calibrator for MAROON-X

NASA Astrophysics Data System (ADS)

Stürmer, Julian; Seifahrt, Andreas; Schwab, Christian; Bean, Jacob L.

2016-07-01

We report on the construction and testing of a vacuum-gap Fabry-Perot etalon calibrator for high precision radial velocity spectrographs. The etalon is referenced against hyper fine transitions of rubidium to provide a precise wavelength calibrator for MAROON-X, a new fiber-fed, red-optical, high-precision radial-velocity spectrograph currently under construction for one of the twin 6.5m Magellan Telescopes in Chile. We demonstrate a turnkey system, ready to be installed at any current and next generation radial velocity spectrograph that requires calibration over a wide spectral band-pass. Uncertainties in the position of one etalon line are at the 10 cm s-1 level in individual measurements taken at 4 Hz. Our long-term stability is mainly limited by aging effects of the spacer material Zerodur, which imprints a 12 cm s-1 daily drift. However, as the etalon position is traced by the rubidium reference with a precision of <3 cm s-1 for integration times longer than 10s, we can fully account for this effect at the RV data reduction level.

Compact Integration of a GSM-19 Magnetic Sensor with High-Precision Positioning using VRS GNSS Technology

PubMed Central

Martín, Angel; Padín, Jorge; Anquela, Ana Belén; Sánchez, Juán; Belda, Santiago

2009-01-01

Magnetic data consists of a sequence of collected points with spatial coordinates and magnetic information. The spatial location of these points needs to be as exact as possible in order to develop a precise interpretation of magnetic anomalies. GPS is a valuable tool for accomplishing this objective, especially if the RTK approach is used. In this paper the VRS (Virtual Reference Station) technique is introduced as a new approach for real-time positioning of magnetic sensors. The main advantages of the VRS approach are, firstly, that only a single GPS receiver is needed (no base station is necessary), reducing field work and equipment costs. Secondly, VRS can operate at distances separated 50–70 km from the reference stations without degrading accuracy. A compact integration of a GSM-19 magnetometer sensor with a geodetic GPS antenna is presented; this integration does not diminish the operational flexibility of the original magnetometer and can work with the VRS approach. The coupled devices were tested in marshlands around Gandia, a city located approximately 100 km South of Valencia (Spain), thought to be the site of a Roman cemetery. The results obtained show adequate geometry and high-precision positioning for the structures to be studied (a comparison with the original low precision GPS of the magnetometer is presented). Finally, the results of the magnetic survey are of great interest for archaeological purposes. PMID:22574055

Direct MSTID mitigation in precise GPS processing

NASA Astrophysics Data System (ADS)

Hernández-Pajares, Manuel; Wielgosz, Pawel; Paziewski, Jacek; Krypiak-Gregorczyk, Anna; Krukowska, Marta; Stepniak, Katarzyna; Kaplon, Jan; Hadas, Tomasz; Sosnica, Krzysztof; Bosy, Jaroslaw; Orus-Perez, Raul; Monte-Moreno, Enric; Yang, Heng; Garcia-Rigo, Alberto; Olivares-Pulido, Germán.

2017-03-01

In this paper, the authors summarize a simple and efficient approach developed to mitigate the problem in precise Global Navigation Satellite Systems (GNSS) positioning originated by the most frequent ionospheric wave signatures: the medium-scale traveling ionospheric disturbances (MSTIDs). The direct GNSS Ionospheric Interferometry technique (hereinafter dGII), presented in this paper, is applied for correcting MSTID effects on precise Real Time Kinematic (RTK) and tropospheric determination. It consists of the evolution of the former climatic Differential Delay Mitigation Model for MSTIDs (DMTID), for real-time conditions, using ionospheric data from a single permanent receiver only. The performance is demonstrated with networks of GNSS receivers in Poland, treated as users under real-time conditions, during two representative days in winter and summer seasons (days 353 and 168 of year 2013). In range domain, dGII typically reduces the ionospheric delay error up to 10-90% of the value when the MSTID mitigation model is not applied. The main dGII impact on precise positioning is that we can obtain reliable RTK position faster. In particular, the ambiguity success rate parameter increases, from 74% to 83%, with respect to the original uncorrected observations. The average of time to first fix is shortened from 30 s to 13 s. The improvement in troposphere estimaton, due to any potential impact of the MSTID mitigation model, was most difficult to demonstrate.

[Endoscopically controlled optimization of trans-scleral suture fixation of posterior chamber lenses in the ciliary sulcus].

PubMed

Althaus, C; Sundmacher, R

1993-08-01

Two technical difficulties have to be overcome in transscleral suture fixation of posterior chamber intraocular lenses (PCL) in the ciliary sulcus: first, exact needle penetration through the sulcus, and second, exact positioning of the PCL haptics in the sulcus. Incongruence of the two may lead to long-term complications by compression or even strangulation of ciliary processes. Intraocular endoscopy was used intraoperatively to visualize the site of needle penetration and the final location of the haptics in patients. It turned out that with our previously described standard techniques the precision was far less than anticipated. Thus, new technical ways had to be sought to improve the precision of positioning. In secondary implantation without perforating keratoplasty we achieved the best results when the needle was passed ab externo before opening the eye and before anterior vitrectomy, taking advantage of a precisely prepared sclerocorneal zone. Passing the needle ab externo in an already hypotonic eyeball gives much less precise results. In combination with perforating keratoplasty with an open-sky approach, needle penetration ab interno is reliable. Correct positioning of the PCL haptics is at least as difficult as correct needle penetration, a fact which up to now has mostly been ignored. In 33 consecutively operated eyes the technique of implantation and PCL design was varied under endoscopical control.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer graphics of SEM images facilitate recognition of chromosome position in isolated human metaphase plates.

PubMed

Hodge, L D; Barrett, J M; Welter, D A

1995-04-01

There is general agreement that at the time of mitosis chromosomes occupy precise positions and that these positions likely affect subsequent nuclear function in interphase. However, before such ideas can be investigated in human cells, it is necessary to determine first the precise position of each chromosome with regard to its neighbors. It has occurred to us that stereo images, produced by scanning electron microscopy, of isolated metaphase plates could form the basis whereby these positions could be ascertained. In this paper we describe a computer graphic technique that permits us to keep track of individual chromosomes in a metaphase plate and to compare chromosome positions in different metaphase plates. Moreover, the computer graphics provide permanent, easily manipulated, rapid recall of stored chromosome profiles. These advantages are demonstrated by a comparison of the relative position of group A-specific and groups D- and G-specific chromosomes to the full complement of chromosomes in metaphase plates isolated from a nearly triploid human-derived cell (HeLa S3) to a hypo-diploid human fetal lung cell.

Sternal instability measured with radiostereometric analysis. A study of method feasibility, accuracy and precision.

PubMed

Vestergaard, Rikke Falsig; Søballe, Kjeld; Hasenkam, John Michael; Stilling, Maiken

2018-05-18

A small, but unstable, saw-gap may hinder bone-bridging and induce development of painful sternal dehiscence. We propose the use of Radiostereometric Analysis (RSA) for evaluation of sternal instability and present a method validation. Four bone analogs (phantoms) were sternotomized and tantalum beads were inserted in each half. The models were reunited with wire cerclage and placed in a radiolucent separation device. Stereoradiographs (n = 48) of the phantoms in 3 positions were recorded at 4 imposed separation points. The accuracy and precision was compared statistically and presented as translations along the 3 orthogonal axes. 7 sternotomized patients were evaluated for clinical RSA precision by double-examination stereoradiographs (n = 28). In the phantom study, we found no systematic error (p > 0.3) between the three phantom positions, and precision for evaluation of sternal separation was 0.02 mm. Phantom accuracy was mean 0.13 mm (SD 0.25). In the clinical study, we found a detection limit of 0.42 mm for sternal separation and of 2 mm for anterior-posterior dislocation of the sternal halves for the individual patient. RSA is a precise and low-dose image modality feasible for clinical evaluation of sternal stability in research. ClinicalTrials.gov Identifier: NCT02738437 , retrospectively registered.

Application of high-precision two-way ranging to Galileo Earth-1 encounter navigation

NASA Technical Reports Server (NTRS)

Pollmeier, V. M.; Thurman, S. W.

1992-01-01

The application of precision two-way ranging to orbit determination with relatively short data arcs is investigated for the Galileo spacecraft's approach to its first Earth encounter (December 8, 1990). Analysis of previous S-band (2.3-GHz) ranging data acquired from Galileo indicated that under good signal conditions submeter precision and 10-m ranging accuracy were achieved. It is shown that ranging data of sufficient accuracy, when acquired from multiple stations, can sense the geocentric angular position of a distant spacecraft. A range data filtering technique, in which explicit modeling of range measurement bias parameters for each station pass is utilized, is shown to largely remove the systematic ground system calibration errors and transmission media effects from the Galileo range measurements, which would otherwise corrupt the angle-finding capabilities of the data. The accuracy of the Galileo orbit solutions obtained with S-band Doppler and precision ranging were found to be consistent with simple theoretical calculations, which predicted that angular accuracies of 0.26-0.34 microrad were achievable. In addition, the navigation accuracy achieved with precision ranging was marginally better than that obtained using delta-differenced one-way range (delta DOR), the principal data type that was previously used to obtain spacecraft angular position measurements operationally.

Gravity model improvement using the DORIS tracking system on the SPOT 2 satellite

NASA Technical Reports Server (NTRS)

Nerem, R. S.; Lerch, F. J.; Williamson, R. G.; Klosko, S. M.; Robbins, J. W.; Patel, G. B.

1994-01-01

A high-precision radiometric satellite tracking system, Doppler Orbitography and Radio-positioning Integrated by Satellite system (DORIS), has recently been developed by the French space agency, Centre National d'Etudes Spatiales (CNES). DORIS was designed to provide tracking support for missions such as the joint United States/French TOPEX/Poseidon. As part of the flight testing process, a DORIS package was flown on the French SPOT 2 satellite. A substantial quantity of geodetic quality tracking data was obtained on SPOT 2 from an extensive international DORIS tracking network. These data were analyzed to assess their accuracy and to evaluate the gravitational modeling enhancements provided by these data in combination with the Goddard Earth Model-T3 (GEM-T3) gravitational model. These observations have noise levels of 0.4 to 0.5 mm/s, with few residual systematic effects. Although the SPOT 2 satellite experiences high atmospheric drag forces, the precision and global coverage of the DORIS tracking data have enabled more extensive orbit parameterization to mitigate these effects. As a result, the SPOT 2 orbital errors have been reduced to an estimated radial accuracy in the 10-20 cm RMS range. The addition of these data, which encompass many regions heretofore lacking in precision satellite tracking, has significantly improved GEM-T3 and allowed greatly improved orbit accuracies for Sun-synchronous satellites like SPOT 2 (such as ERS 1 and EOS). Comparison of the ensuing gravity model with other contemporary fields (GRIM-4C2, TEG2B, and OSU91A) provides a means to assess the current state of knowledge of the Earth's gravity field. Thus, the DORIS experiment on SPOT 2 has provided a strong basis for evaluating this new orbit tracking technology and has demonstrated the important contribution of the DORIS network to the success of the TOPEX/Poseidon mission.

Dynamic changes of RNA-sequencing expression for precision medicine: N-of-1-pathways Mahalanobis distance within pathways of single subjects predicts breast cancer survival

PubMed Central

Piegorsch, Walter W.; Lussier, Yves A.

2015-01-01

Motivation: The conventional approach to personalized medicine relies on molecular data analytics across multiple patients. The path to precision medicine lies with molecular data analytics that can discover interpretable single-subject signals (N-of-1). We developed a global framework, N-of-1-pathways, for a mechanistic-anchored approach to single-subject gene expression data analysis. We previously employed a metric that could prioritize the statistical significance of a deregulated pathway in single subjects, however, it lacked in quantitative interpretability (e.g. the equivalent to a gene expression fold-change). Results: In this study, we extend our previous approach with the application of statistical Mahalanobis distance (MD) to quantify personal pathway-level deregulation. We demonstrate that this approach, N-of-1-pathways Paired Samples MD (N-OF-1-PATHWAYS-MD), detects deregulated pathways (empirical simulations), while not inflating false-positive rate using a study with biological replicates. Finally, we establish that N-OF-1-PATHWAYS-MD scores are, biologically significant, clinically relevant and are predictive of breast cancer survival (P < 0.05, n = 80 invasive carcinoma; TCGA RNA-sequences). Conclusion: N-of-1-pathways MD provides a practical approach towards precision medicine. The method generates the magnitude and the biological significance of personal deregulated pathways results derived solely from the patient’s transcriptome. These pathways offer the opportunities for deriving clinically actionable decisions that have the potential to complement the clinical interpretability of personal polymorphisms obtained from DNA acquired or inherited polymorphisms and mutations. In addition, it offers an opportunity for applicability to diseases in which DNA changes may not be relevant, and thus expand the ‘interpretable ‘omics’ of single subjects (e.g. personalome). Availability and implementation: http://www.lussierlab.net/publications/N-of-1-pathways. Contact: yves@email.arizona.edu or piegorsch@math.arizona.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:26072495

Study on individual stochastic model of GNSS observations for precise kinematic applications

NASA Astrophysics Data System (ADS)

Próchniewicz, Dominik; Szpunar, Ryszard

2015-04-01

The proper definition of mathematical positioning model, which is defined by functional and stochastic models, is a prerequisite to obtain the optimal estimation of unknown parameters. Especially important in this definition is realistic modelling of stochastic properties of observations, which are more receiver-dependent and time-varying than deterministic relationships. This is particularly true with respect to precise kinematic applications which are characterized by weakening model strength. In this case, incorrect or simplified definition of stochastic model causes that the performance of ambiguity resolution and accuracy of position estimation can be limited. In this study we investigate the methods of describing the measurement noise of GNSS observations and its impact to derive precise kinematic positioning model. In particular stochastic modelling of individual components of the variance-covariance matrix of observation noise performed using observations from a very short baseline and laboratory GNSS signal generator, is analyzed. Experimental test results indicate that the utilizing the individual stochastic model of observations including elevation dependency and cross-correlation instead of assumption that raw measurements are independent with the same variance improves the performance of ambiguity resolution as well as rover positioning accuracy. This shows that the proposed stochastic assessment method could be a important part in complex calibration procedure of GNSS equipment.

Theoretical and experimental research on machine tool servo system for ultra-precision position compensation on CNC lathe

NASA Astrophysics Data System (ADS)

Ma, Zhichao; Hu, Leilei; Zhao, Hongwei; Wu, Boda; Peng, Zhenxing; Zhou, Xiaoqin; Zhang, Hongguo; Zhu, Shuai; Xing, Lifeng; Hu, Huang

2010-08-01

The theories and techniques for improving machining accuracy via position control of diamond tool's tip and raising resolution of cutting depth on precise CNC lathes have been extremely focused on. A new piezo-driven ultra-precision machine tool servo system is designed and tested to improve manufacturing accuracy of workpiece. The mathematical model of machine tool servo system is established and the finite element analysis is carried out on parallel plate flexure hinges. The output position of diamond tool's tip driven by the machine tool servo system is tested via a contact capacitive displacement sensor. Proportional, integral, derivative (PID) feedback is also implemented to accommodate and compensate dynamical change owing cutting forces as well as the inherent non-linearity factors of the piezoelectric stack during cutting process. By closed loop feedback controlling strategy, the tracking error is limited to 0.8 μm. Experimental results have shown the proposed machine tool servo system could provide a tool positioning resolution of 12 nm, which is much accurate than the inherent CNC resolution magnitude. The stepped shaft of aluminum specimen with a step increment of cutting depth of 1 μm is tested, and the obtained contour illustrates the displacement command output from controller is accurately and real-time reflected on the machined part.

A Unified Model for BDS Wide Area and Local Area Augmentation Positioning Based on Raw Observations.

PubMed

Tu, Rui; Zhang, Rui; Lu, Cuixian; Zhang, Pengfei; Liu, Jinhai; Lu, Xiaochun

2017-03-03

In this study, a unified model for BeiDou Navigation Satellite System (BDS) wide area and local area augmentation positioning based on raw observations has been proposed. Applying this model, both the Real-Time Kinematic (RTK) and Precise Point Positioning (PPP) service can be realized by performing different corrections at the user end. This algorithm was assessed and validated with the BDS data collected at four regional stations from Day of Year (DOY) 080 to 083 of 2016. When the users are located within the local reference network, the fast and high precision RTK service can be achieved using the regional observation corrections, revealing a convergence time of about several seconds and a precision of about 2-3 cm. For the users out of the regional reference network, the global broadcast State-Space Represented (SSR) corrections can be utilized to realize the global PPP service which shows a convergence time of about 25 min for achieving an accuracy of 10 cm. With this unified model, it can not only integrate the Network RTK (NRTK) and PPP into a seamless positioning service, but also recover the ionosphere Vertical Total Electronic Content (VTEC) and Differential Code Bias (DCB) values that are useful for the ionosphere monitoring and modeling.

A Unified Model for BDS Wide Area and Local Area Augmentation Positioning Based on Raw Observations

PubMed Central

Tu, Rui; Zhang, Rui; Lu, Cuixian; Zhang, Pengfei; Liu, Jinhai; Lu, Xiaochun

2017-01-01

In this study, a unified model for BeiDou Navigation Satellite System (BDS) wide area and local area augmentation positioning based on raw observations has been proposed. Applying this model, both the Real-Time Kinematic (RTK) and Precise Point Positioning (PPP) service can be realized by performing different corrections at the user end. This algorithm was assessed and validated with the BDS data collected at four regional stations from Day of Year (DOY) 080 to 083 of 2016. When the users are located within the local reference network, the fast and high precision RTK service can be achieved using the regional observation corrections, revealing a convergence time of about several seconds and a precision of about 2–3 cm. For the users out of the regional reference network, the global broadcast State-Space Represented (SSR) corrections can be utilized to realize the global PPP service which shows a convergence time of about 25 min for achieving an accuracy of 10 cm. With this unified model, it can not only integrate the Network RTK (NRTK) and PPP into a seamless positioning service, but also recover the ionosphere Vertical Total Electronic Content (VTEC) and Differential Code Bias (DCB) values that are useful for the ionosphere monitoring and modeling. PMID:28273814

Multi-GNSS real-time precise positioning service and Initial assessment of BDS-3 (G Division Outstanding ECS Award Lecture)

NASA Astrophysics Data System (ADS)

Li, Xingxing; Ge, Maaorong; Li, Xin; Zhang, Xiuaohong; Wu, Mingkui; Wickert, Jens; Schuh, Harald

2017-04-01

The rapid development of multi-constellation GNSSs (Global Navigation Satellite Systems, e.g., BeiDou, Galileo, GLONASS, GPS) and the IGS (International GNSS Service) Multi-GNSS Experiment (MGEX) bring great opportunities and challenges for real-time precise positioning service. In this contribution, we present a GPS+GLONASS+BeiDou+Galileo four-system model to fully exploit the observations of all these four navigation satellite systems for real-time precise orbit determination, clock estimation and positioning. Meanwhile, an efficient multi-GNSS real-time precise positioning service system is designed and demonstrated by using the Multi-GNSS Experiment (MGEX) and International GNSS Service (IGS) data streams including stations all over the world. The addition of the BeiDou, Galileo and GLONASS systems to the standard GPS-only processing, reduces the convergence time almost by 70%, while the positioning accuracy is improved by about 25%. The successful launch of five new-generation satellites of the Chinese BeiDou Navigation Satellite System (BDS-3) marks a significant step in expanding BeiDou into a navigation system with global coverage. We present an initial characterization and performance assessment for these new-generation BeiDou-3 satellites and their signals. The characteristics of the B1C, B1I, B2a, B2b and B3I signals are evaluated in terms of observed carrier-to-noise density ratio, pseudorange multipath and noise, triple-frequency carrier phase ionosphere-free and geometry-free combination, and double-differenced carrier phase and code residuals. With respect to BeiDou-2 satellites, the analysis of code multipath shows that the elevation-dependent code biases, which have been previously identified to exist in the code observations of BeiDou-2 satellites, seem to be not obvious for all the available signals of new-generation BeiDou-3 satellites. This will significantly benefit precise applications that resolve wide-lane ambiguity based on Melbourne-Wübbena (MW) linear combinations and other applications such as single-frequency Precise Point Positioning (PPP) based on the ionosphere free code-carrier combinations. With regard to the triple-frequency carrier phase ionosphere-free and geometry-free combinations, it is found that different from BeiDou-2 and GPS Block IIF satellites, no apparent bias variations could be observed in all the new-generation BeiDou-3 satellites, which show a good consistency of the new-generation BeiDou-3 signals. The absence of such triple-frequency biases will make it convenient for the future processing of multi-frequency PPP using observations from new-generation BeiDou-3 satellites.

Precise Orbit Determination of BeiDou Navigation Satellite System

NASA Astrophysics Data System (ADS)

He, Lina; Ge, Maorong; Wang, Jiexian; Wickert, Jens; Schuh, Harald

2013-04-01

China has been developing its own independent satellite navigation system since decades. Now the COMPASS system, also known as BeiDou, is emerging and gaining more and more interest and attention in the worldwide GNSS communities. The current regional BeiDou system is ready for its operational service around the end of 2012 with a constellation including five Geostationary Earth Orbit satellites (GEO), five Inclined Geosynchronous Orbit satellites (IGSO) and four Medium Earth orbit (MEO) satellites in operation. Besides the open service with positioning accuracy of around 10m which is free to civilian users, both precise relative positioning, and precise point positioning are demonstrated as well. In order to enhance the BeiDou precise positioning service, Precise Orbit Determination (POD) which is essential of any satellite navigation system has been investigated and studied thoroughly. To further improving the orbits of different types of satellites, we study the impact of network coverage on POD data products by comparing results from tracking networks over the Chinese territory, Asian-Pacific, Asian and of global scale. Furthermore, we concentrate on the improvement of involving MEOs on the orbit quality of GEOs and IGSOs. POD with and without MEOs are undertaken and results are analyzed. Finally, integer ambiguity resolution which brings highly improvement on orbits and positions with GPS data is also carried out and its effect on POD data products is assessed and discussed in detail. Seven weeks of BeiDou data from a ground tracking network, deployed by Wuhan University is employed in this study. The test constellation includes four GEO, five IGSO and two MEO satellites in operation. The three-day solution approach is employed to enhance its strength due to the limited coverage of the tracking network and the small movement of most of the satellites. A number of tracking scenarios and processing schemas are identified and processed and overlapping orbit differences are utilized to qualify the estimated orbits and clocks. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. For the current tracking network, deploying tracking stations on the eastern side, for example in New Zealand and/or in Hawaii, will significantly reduce along-track biases of GEOs on the same side. The involvement of MEOs and ambiguity-fixing also make the orbits better but rather moderate. Key words: BeiDou, precise orbit determination (POD), tracking network, ambiguity-fixing

Lack of Precision of Burn Surface Area Calculation by UK Armed Forces Medical Personnel

DTIC Science & Technology

2014-03-01

computer screen or tablet , and therefore the variability in perception and representation inherent in having a human assess and draw the burn remains...Potential solutions to this source of error include 3D MRI and TeraHertz scanning technologies [40], but at the time of writing, these are not yet

A Survey of Attitudes towards Critical Thinking among Hong Kong Secondary School Teachers: Implications for Policy Change

ERIC Educational Resources Information Center

Stapleton, Paul

2011-01-01

The term "critical thinking" (CT) is frequently found in educational policy documents in sections outlining curriculum goals. Despite this frequency, however, precise understandings among teachers of what CT really means are lacking. In this study, 72 high school teachers in Hong Kong were surveyed and interviewed on their beliefs about…

Teaching, in Spite of Excellence: Recovering a Practice of Teaching-Led Research

ERIC Educational Resources Information Center

Charles, Matthew

2018-01-01

Although, as a result of the introduction of the Teaching Excellence Framework, the principle of teaching excellence is receiving renewed attention in English higher education, the idea has been left largely undefined. The cynic might argue, in agreement with Bill Readings, that this lack of a precise definition is deliberate, since teaching…

Assessing Developmental Trajectories of Sexual Minority Youth: Discrepant Findings from a Life History Calendar and a Self-Administered Survey

ERIC Educational Resources Information Center

Fisher, Colleen M.

2012-01-01

Research suggests that the timing and sequence of sexual identity development milestones impact myriad health and mental health outcomes for sexual minority youth. Because these milestone events are typically assessed retrospectively, traditional data collection approaches are limited by recall bias and lack of precision in the recording of…

Psychometric Properties and Rater Effects of the Computer Adaptive Test of Functional Cognition for Traumatic Brain Injury

ERIC Educational Resources Information Center

Wen, Pey-Shan

2009-01-01

Individuals with moderate to severe TBI often need extensive rehabilitation. To verify the effectiveness of intervention and design rehabilitation programs that meet individual's needs, precise and efficient outcome measures are crucial. Current assessments for TBI either focus on measuring impairments, such as neuropsychological tests or lack of…

Simple Assessment Techniques for Soil and Water. Environmental Factors in Small Scale Development Projects. Workshops.

ERIC Educational Resources Information Center

Coordination in Development, New York, NY.

This booklet was produced in response to the growing need for reliable environmental assessment techniques that can be applied to small-scale development projects. The suggested techniques emphasize low-technology environmental analysis. Although these techniques may lack precision, they can be extremely valuable in helping to assure the success…

Notes From the Field: Secondary Task Precision for Cognitive Load Estimation During Virtual Reality Surgical Simulation Training.

PubMed

Rasmussen, Sebastian R; Konge, Lars; Mikkelsen, Peter T; Sørensen, Mads S; Andersen, Steven A W

2016-03-01

Cognitive load (CL) theory suggests that working memory can be overloaded in complex learning tasks such as surgical technical skills training, which can impair learning. Valid and feasible methods for estimating the CL in specific learning contexts are necessary before the efficacy of CL-lowering instructional interventions can be established. This study aims to explore secondary task precision for the estimation of CL in virtual reality (VR) surgical simulation and also investigate the effects of CL-modifying factors such as simulator-integrated tutoring and repeated practice. Twenty-four participants were randomized for visual assistance by a simulator-integrated tutor function during the first 5 of 12 repeated mastoidectomy procedures on a VR temporal bone simulator. Secondary task precision was found to be significantly lower during simulation compared with nonsimulation baseline, p < .001. Contrary to expectations, simulator-integrated tutoring and repeated practice did not have an impact on secondary task precision. This finding suggests that even though considerable changes in CL are reflected in secondary task precision, it lacks sensitivity. In contrast, secondary task reaction time could be more sensitive, but requires substantial postprocessing of data. Therefore, future studies on the effect of CL modifying interventions should weigh the pros and cons of the various secondary task measurements. © The Author(s) 2015.

Sustained attention to objects' motion sharpens position representations: Attention to changing position and attention to motion are distinct.

PubMed

Howard, Christina J; Rollings, Victoria; Hardie, Amy

2017-06-01

In tasks where people monitor moving objects, such the multiple object tracking task (MOT), observers attempt to keep track of targets as they move amongst distracters. The literature is mixed as to whether observers make use of motion information to facilitate performance. We sought to address this by two means: first by superimposing arrows on objects which varied in their informativeness about motion direction and second by asking observers to attend to motion direction. Using a position monitoring task, we calculated mean error magnitudes as a measure of the precision with which target positions are represented. We also calculated perceptual lags versus extrapolated reports, which are the times at which positions of targets best match position reports. We find that the presence of motion information in the form of superimposed arrows made no difference to position report precision nor perceptual lag. However, when we explicitly instructed observers to attend to motion, we saw facilitatory effects on position reports and in some cases reports that best matched extrapolated rather than lagging positions for small set sizes. The results indicate that attention to changing positions does not automatically recruit attention to motion, showing a dissociation between sustained attention to changing positions and attention to motion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vehicle parts detection based on Faster - RCNN with location constraints of vehicle parts feature point

NASA Astrophysics Data System (ADS)

Yang, Liqin; Sang, Nong; Gao, Changxin

2018-03-01

Vehicle parts detection plays an important role in public transportation safety and mobility. The detection of vehicle parts is to detect the position of each vehicle part. We propose a new approach by combining Faster RCNN and three level cascaded convolutional neural network (DCNN). The output of Faster RCNN is a series of bounding boxes with coordinate information, from which we can locate vehicle parts. DCNN can precisely predict feature point position, which is the center of vehicle part. We design an output strategy by combining these two results. There are two advantages for this. The quality of the bounding boxes are greatly improved, which means vehicle parts feature point position can be located more precise. Meanwhile we preserve the position relationship between vehicle parts and effectively improve the validity and reliability of the result. By using our algorithm, the performance of the vehicle parts detection improve obviously compared with Faster RCNN.

Human leader and robot follower team: correcting leader's position from follower's heading

NASA Astrophysics Data System (ADS)

Borenstein, Johann; Thomas, David; Sights, Brandon; Ojeda, Lauro; Bankole, Peter; Fellars, Donald

2010-04-01

In multi-agent scenarios, there can be a disparity in the quality of position estimation amongst the various agents. Here, we consider the case of two agents - a leader and a follower - following the same path, in which the follower has a significantly better estimate of position and heading. This may be applicable to many situations, such as a robotic "mule" following a soldier. Another example is that of a convoy, in which only one vehicle (not necessarily the leading one) is instrumented with precision navigation instruments while all other vehicles use lower-precision instruments. We present an algorithm, called Follower-derived Heading Correction (FDHC), which substantially improves estimates of the leader's heading and, subsequently, position. Specifically, FHDC produces a very accurate estimate of heading errors caused by slow-changing errors (e.g., those caused by drift in gyros) of the leader's navigation system and corrects those errors.

Research regarding stiffness optimization of wires used for joints actuation from an elephant's trunk robotic arm

NASA Astrophysics Data System (ADS)

Ciofu, C.; Stan, G.

2016-11-01

Elephant's trunk robotic arms driven by wires and pulley mechanisms have issues with wires stiffness because of the entailed elastic deformations that is causing errors of positioning. Static and dynamic loads from each joint of the robotic arm affect the stiffness of driving wires and precision positioning. The influence of wires elastic deformation on precision positioning decreases with the increasing of wires stiffness by using different pre-tensioning devices. In this paper, we analyze the variation of driving wires stiffness particularly to each wire driven joint. We obtain optimum wires stiffness variation by using an analytical method that highlights the efficiency of pre-tensioning mechanism. The analysis of driving wires stiffness is necessary for taking appropriate optimization measures of robotic arm dynamic behavior and, thus, for decreasing positioning errors of the elephant's trunk robotic arm with inner actuation through wires/cables.

Investigation of practical and theoretical accuracy of wireless indoor-positioning system UBISENSE

NASA Astrophysics Data System (ADS)

Wozniak, Marek; Odziemczyk, Waldemar; Nagorski, Kamil

2013-04-01

The development of Real Time Locating Systems has become an important add-on to many existing location aware systems. While Global Navigation Satelite System has solved most of the outdoor problems, it fails to repeat this success indoors. Wireless indoor positioning systems have become very popular in recent years. One of them is UBISENSE system. This system requires to carry an identity tag that is detected by sensors, which typically use triangulation to determine location. This paper presents the results of the investigation of accuracy of tag position using precise geodetic measurements and geometric analysis. Experimental measurements were carried out on the field polygon using precise tacheometer TCRP 1201+ and complete equipment of Ubisense. Results of experimental measurements were analyzed and presented graphically using Surfer 8. The paper presents the results of the investigation the teoretical and practical positioning accuracy according to the various working conditions.

A quantum network of clocks

NASA Astrophysics Data System (ADS)

Komar, Peter; Kessler, Eric; Bishof, Michael; Jiang, Liang; Sorensen, Anders; Ye, Jun; Lukin, Mikhail

2014-05-01

Shared timing information constitutes a key resource for positioning and navigation with a direct correspondence between timing accuracy and precision in applications such as the Global Positioning System (GPS). By combining precision metrology and quantum networks, we propose here a quantum, cooperative protocol for the operation of a network consisting of geographically remote optical atomic clocks. Using non-local entangled states, we demonstrate an optimal utilization of the global network resources, and show that such a network can be operated near the fundamental limit set by quantum theory yielding an ultra-precise clock signal. Furthermore, the internal structure of the network, combined with basic techniques from quantum communication, guarantees security both from internal and external threats. Realization of such a global quantum network of clocks may allow construction of a real-time single international time scale (world clock) with unprecedented stability and accuracy. See also: Komar et al. arXiv:1310.6045 (2013) and Kessler et al. arXiv:1310.6043 (2013).

Precise through-space control of an abiotic electrophilic aromatic substitution reaction

NASA Astrophysics Data System (ADS)

Murphy, Kyle E.; Bocanegra, Jessica L.; Liu, Xiaoxi; Chau, H.-Y. Katharine; Lee, Patrick C.; Li, Jianing; Schneebeli, Severin T.

2017-04-01

Nature has evolved selective enzymes for the efficient biosynthesis of complex products. This exceptional ability stems from adapted enzymatic pockets, which geometrically constrain reactants and stabilize specific reactive intermediates by placing electron-donating/accepting residues nearby. Here we perform an abiotic electrophilic aromatic substitution reaction, which is directed precisely through space. Ester arms--positioned above the planes of aromatic rings--enable it to distinguish between nearly identical, neighbouring reactive positions. Quantum mechanical calculations show that, in two competing reaction pathways, both [C-H...O]-hydrogen bonding and electrophile preorganization by coordination to a carbonyl group likely play a role in controlling the reaction. These through-space-directed mechanisms are inspired by dimethylallyl tryptophan synthases, which direct biological electrophilic aromatic substitutions by preorganizing dimethylallyl cations and by stabilizing reactive intermediates with [C-H...N]-hydrogen bonding. Our results demonstrate how the third dimension above and underneath aromatic rings can be exploited to precisely control electrophilic aromatic substitutions.

3D atom microscopy in the presence of Doppler shift

NASA Astrophysics Data System (ADS)

Rahmatullah; Chuang, You-Lin; Lee, Ray-Kuang; Qamar, Sajid

2018-03-01

The interaction of hot atoms with laser fields produces a Doppler shift, which can severely affect the precise spatial measurement of an atom. We suggest an experimentally realizable scheme to address this issue in the three-dimensional position measurement of a single atom in vapors of rubidium atoms. A three-level Λ-type atom-field configuration is considered where a moving atom interacts with three orthogonal standing-wave laser fields and spatial information of the atom in 3D space is obtained via an upper-level population using a weak probe laser field. The atom moves with velocity v along the probe laser field, and due to the Doppler broadening the precision of the spatial information deteriorates significantly. It is found that via a microwave field, precision in the position measurement of a single hot rubidium atom can be attained, overcoming the limitation posed by the Doppler shift.

High-precision tracking of brownian boomerang colloidal particles confined in quasi two dimensions.

PubMed

Chakrabarty, Ayan; Wang, Feng; Fan, Chun-Zhen; Sun, Kai; Wei, Qi-Huo

2013-11-26

In this article, we present a high-precision image-processing algorithm for tracking the translational and rotational Brownian motion of boomerang-shaped colloidal particles confined in quasi-two-dimensional geometry. By measuring mean square displacements of an immobilized particle, we demonstrate that the positional and angular precision of our imaging and image-processing system can achieve 13 nm and 0.004 rad, respectively. By analyzing computer-simulated images, we demonstrate that the positional and angular accuracies of our image-processing algorithm can achieve 32 nm and 0.006 rad. Because of zero correlations between the displacements in neighboring time intervals, trajectories of different videos of the same particle can be merged into a very long time trajectory, allowing for long-time averaging of different physical variables. We apply this image-processing algorithm to measure the diffusion coefficients of boomerang particles of three different apex angles and discuss the angle dependence of these diffusion coefficients.

Probing the limits to positional information

PubMed Central

Gregor, Thomas; Tank, David W.; Wieschaus, Eric F.; Bialek, William

2008-01-01

The reproducibility and precision of biological patterning is limited by the accuracy with which concentration profiles of morphogen molecules can be established and read out by their targets. We consider four measures of precision for the Bicoid morphogen in the Drosophila embryo: The concentration differences that distinguish neighboring cells, the limits set by the random arrival of Bicoid molecules at their targets (which depends on absolute concentration), the noise in readout of Bicoid by the activation of Hunchback, and the reproducibility of Bicoid concentration at corresponding positions in multiple embryos. We show, through a combination of different experiments, that all of these quantities are ~10%. This agreement among different measures of accuracy indicates that the embryo is not faced with noisy input signals and readout mechanisms; rather the system exerts precise control over absolute concentrations and responds reliably to small concentration differences, approaching the limits set by basic physical principles. PMID:17632062

Apparatus for Precise Indium-Bump Bonding of Microchips

NASA Technical Reports Server (NTRS)

Wild, Larry; Mulder, Jerry; Alvarado, Nicholas

2005-01-01

An improved apparatus has been designed and built for use in precise positioning and pressing of a microchip onto a substrate (which could, optionally, be another microchip) for the purpose of indium-bump bonding. The apparatus (see figure) includes the following: A stereomicroscope, A stage for precise positioning of the microchip in rotation angle (theta) about the nominally vertical pressing axis and in translation along two nominally horizontal coordinate axes (x and y), and An actuator system that causes a bonding tip to press the microchip against the substrate with a precisely controlled force. In operation, the microscope and the stage are used to position the microchip under the bonding tip and to align the indium bumps on the chip and the substrate, then the actuator system is used to apply a prescribed bonding force for a prescribed time. The improved apparatus supplants a partly similar prior apparatus that operated with less precision and repeatability, producing inconsistent and unreliable bonds. Results of the use of the prior apparatus included broken microchips, uneven bonds, and bonds characterized, variously, by overcompression or undercompression. In that apparatus, the bonding force was generated and controlled by use of a micrometer head positioned over the center of a spring-loaded scale, and the force was applied to the microchip via the scale, which was equipped for digital readout of the force. The inconsistency of results was attributed to the following causes: It was not possible to control the bonding force with sufficient precision or repeatability. Particularly troublesome was the inability to control the force at levels less than the weight of 150 g. Excessive compliance in the spring-loaded scale, combined with deviations from parallelarity of the substrate and bonding-tip surfaces, gave rise to nonuniformity in the pressure applied to the microchip, thereby generating excessive stresses and deformations in the microchip. In the improved apparatus, the bonding tip and the components that hold the substrate and the microchip are more rigid and precise than in the prior apparatus, so as to ensure less deviation from parallelarity of the bonding-tip and substrate surfaces, thereby ensuring more nearly uniform distribution of bonding force over the area of the microchip. The bonding force is now applied through, and measured by, a load cell that makes it possible to exert finer control over the force. The force can be set at any value between 0 and the weight of 800 g in increments of 0.2 g.

Accuracy of a hexapod parallel robot kinematics based external fixator.

PubMed

Faschingbauer, Maximilian; Heuer, Hinrich J D; Seide, Klaus; Wendlandt, Robert; Münch, Matthias; Jürgens, Christian; Kirchner, Rainer

2015-12-01

Different hexapod-based external fixators are increasingly used to treat bone deformities and fractures. Accuracy has not been measured sufficiently for all models. An infrared tracking system was applied to measure positioning maneuvers with a motorized Precision Hexapod® fixator, detecting three-dimensional positions of reflective balls mounted in an L-arrangement on the fixator, simulating bone directions. By omitting one dimension of the coordinates, projections were simulated as if measured on standard radiographs. Accuracy was calculated as the absolute difference between targeted and measured positioning values. In 149 positioning maneuvers, the median values for positioning accuracy of translations and rotations (torsions/angulations) were below 0.3 mm and 0.2° with quartiles ranging from -0.5 mm to 0.5 mm and -1.0° to 0.9°, respectively. The experimental setup was found to be precise and reliable. It can be applied to compare different hexapod-based fixators. Accuracy of the investigated hexapod system was high. Copyright © 2014 John Wiley & Sons, Ltd.

A research on the positioning technology of vehicle navigation system from single source to "ASPN"

NASA Astrophysics Data System (ADS)

Zhang, Jing; Li, Haizhou; Chen, Yu; Chen, Hongyue; Sun, Qian

2017-10-01

Due to the suddenness and complexity of modern warfare, land-based weapon systems need to have precision strike capability on roads and railways. The vehicle navigation system is one of the most important equipments for the land-based weapon systems that have precision strick capability. There are inherent shortcomings for single source navigation systems to provide continuous and stable navigation information. To overcome the shortcomings, the multi-source positioning technology is developed. The All Source Positioning and Navigaiton (ASPN) program was proposed in 2010, which seeks to enable low cost, robust, and seamless navigation solutions for military to use on any operational platform and in any environment with or without GPS. The development trend of vehicle positioning technology was reviewed in this paper. The trend indicates that the positioning technology is developed from single source and multi-source to ASPN. The data fusion techniques based on multi-source and ASPN was analyzed in detail.

Robust stability of second-order systems

NASA Technical Reports Server (NTRS)

Chuang, C.-H.

1995-01-01

It has been shown recently how virtual passive controllers can be designed for second-order dynamic systems to achieve robust stability. The virtual controllers were visualized as systems made up of spring, mass and damping elements. In this paper, a new approach emphasizing on the notion of positive realness to the same second-order dynamic systems is used. Necessary and sufficient conditions for positive realness are presented for scalar spring-mass-dashpot systems. For multi-input multi-output systems, we show how a mass-spring-dashpot system can be made positive real by properly choosing its output variables. In particular, sufficient conditions are shown for the system without output velocity. Furthermore, if velocity cannot be measured then the system parameters must be precise to keep the system positive real. In practice, system parameters are not always constant and cannot be measured precisely. Therefore, in order to be useful positive real systems must be robust to some degrees. This can be achieved with the design presented in this paper.

Modeling and Assessment of GPS/BDS Combined Precise Point Positioning.

PubMed

Chen, Junping; Wang, Jungang; Zhang, Yize; Yang, Sainan; Chen, Qian; Gong, Xiuqiang

2016-07-22

Precise Point Positioning (PPP) technique enables stand-alone receivers to obtain cm-level positioning accuracy. Observations from multi-GNSS systems can augment users with improved positioning accuracy, reliability and availability. In this paper, we present and evaluate the GPS/BDS combined PPP models, including the traditional model and a simplified model, where the inter-system bias (ISB) is treated in different way. To evaluate the performance of combined GPS/BDS PPP, kinematic and static PPP positions are compared to the IGS daily estimates, where 1 month GPS/BDS data of 11 IGS Multi-GNSS Experiment (MGEX) stations are used. The results indicate apparent improvement of GPS/BDS combined PPP solutions in both static and kinematic cases, where much smaller standard deviations are presented in the magnitude distribution of coordinates RMS statistics. Comparisons between the traditional and simplified combined PPP models show no difference in coordinate estimations, and the inter system biases between the GPS/BDS system are assimilated into receiver clock, ambiguities and pseudo-range residuals accordingly.

Precise CCD positions of Phoebe in 2011-2014

NASA Astrophysics Data System (ADS)

Peng, Q. Y.; Wang, N.; Vienne, A.; Zhang, Q. F.; Li, Z.; Meng, X. H.

2015-05-01

346 new CCD observations during the years 2011-2014 have been reduced to derive the precise positions of Phoebe, the ninth satellite of Saturn. The observations were made by the 2.4 m telescope at Yunnan Observatory over nine nights. Due to the use of a focal-reducer on the telescope, its significant geometric distortion is solved for and removed for each CCD field of view. The positions of Phoebe are measured with respect to the stars in UCAC2 catalogue. The theoretical position of Phoebe was retrieved from the Institute de Méchanique Céleste et de Calcul des Éphémérides ephemeris which includes the latest theory PH12 by Desmars et al., while the position of Saturn was obtained from the Jet Propulsion Laboratory ephemeris DE431. Our results show that the mean O-Cs (observed minus computed) are -0.02 and -0.07 arcsec in right ascension and declination, respectively. The dispersions of our observations are estimated at about 0.04 arcsec in each direction.

Controlled Chemical Doping of Semiconductor Nanocrystals Using Redox Buffers

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

Engel, Jesse H.; Surendranath, Yogesh; Alivisatos, Paul

Semiconductor nanocrystal solids are attractive materials for active layers in next-generation optoelectronic devices; however, their efficient implementation has been impeded by the lack of precise control over dopant concentrations. Herein we demonstrate a chemical strategy for the controlled doping of nanocrystal solids under equilibrium conditions. Exposing lead selenide nanocrystal thin films to solutions containing varying proportions of decamethylferrocene and decamethylferrocenium incrementally and reversibly increased the carrier concentration in the solid by 2 orders of magnitude from their native values. This application of redox buffers for controlled doping provides a new method for the precise control of the majority carrier concentrationmore » in porous semiconductor thin films.« less

Optical excitation of carbon nanotubes drives stoichiometric reaction with diazonium salts

NASA Astrophysics Data System (ADS)

Powell, Lyndsey; Piao, Yanmei; Wang, Yuhuang; YuHuang Wang Research Group Team

Covalent chemistry is known to lack the precision required to tailor the physical properties of carbon nanostructures. Here we show that, for the first time, light can be used to drive a typically inefficient reaction with single-walled carbon nanotubes in a more stoichiometric fashion. Specifically, our experimental results suggest that light can enhance the reaction rate of diazonium salt with carbon nanotubes by as much as 35-fold, making possible stoichiometric control of the covalent bonding of a functional group to the sp2 carbon lattice. This light-controlled reaction paves the way for the possibility of highly selective and precise chemistry on single-walled carbon nanotubes and other graphitic nanostructures.

Office of Spaceflight Standard Spaceborne Global Positioning System (GPS) user equipment project

NASA Technical Reports Server (NTRS)

Saunders, Penny E.

1991-01-01

The Global Positioning System (GPS) provides the following: (1) position and velocity determination to support vehicle GN&C, precise orbit determination, and payload pointing; (2) time reference to support onboard timing systems and data time tagging; (3) relative position and velocity determination to support cooperative vehicle tracking; and (4) attitude determination to support vehicle attitude control and payload pointing.

HASHIMOTO THYROIDITIS AND VESTIBULAR DYSFUNCTION.

PubMed

Chiarella, Giuseppe; Russo, Diego; Monzani, Fabio; Petrolo, Claudio; Fattori, Bruno; Pasqualetti, Giuseppe; Cassandro, Ettore; Costante, Giuseppe

2017-07-01

The aim of this review was to analyze the existing literature concerning the relationship between Hashimoto thyroiditis (HT) and vestibular dysfunction. We used electronic databases (PubMed, EMBASE, Cochrane Library) to search and collect all published articles about the association between HT and vestibular disorders. Several observational and retrospective studies have postulated a relationship between thyroid autoimmunity and vestibular disorders. In most cases, an appropriate control group was lacking, and the impact of thyroid functional status could not precisely be established. In recent years, two well-designed prospective studies have provided convincing evidence that the association is not random. One article reported that patients with Ménière disease (MD) had a significantly higher prevalence of positive anti-thyroid autoantibody as compared to healthy controls. Moreover, more than half of MD patients had either positive anti-thyroid or non-organ-specific autoantibody titers, compared to less than 30% of both patients with unilateral vestibular paresis without cochlear involvement and healthy controls. Another study found that patients with benign paroxysmal positional vertigo (BPPV) had significantly higher serum thyroid-stimulating hormone and antithyroid autoantibody levels than healthy controls. Additionally, almost one-fifth of euthyroid patients with HT had signs of BPPV. The published results indicate that patients with MD or BPPV are potential candidates to also develop HT. Thus, in HT patients, the presence of even slight symptoms or signs potentially related to vestibular lesions should be carefully investigated. AITD = autoimmune thyroid disease; BPPV = benign paroxysmal positional vertigo; EH = endolymphatic hydrops; HT = Hashimoto thyroiditis; L-T 4 = L-thyroxine; MD = Ménière disease; PS = Pendred syndrome; Tg = thyroglobulin; TPO = thyroid peroxidase; TSH = thyroid-stimulating hormone.

While Heisenberg Is Not Looking: The Strength of "Weak Measurements" in Educational Research

ERIC Educational Resources Information Center

Geelan, David R.

2015-01-01

The concept of "weak measurements" in quantum physics is a way of "cheating" the Uncertainty Principle. Heisenberg stated (and 85 years of experiments have demonstrated) that it is impossible to know both the position and momentum of a particle with arbitrary precision. More precise measurements of one decrease the precision…

The International GPS Service (IGS) as a Continuous Reference System for Precise GPS Positioning

NASA Technical Reports Server (NTRS)

Neilan, Ruth; Heflin, Michael; Watkins, Michael; Zumberge, James

1996-01-01

The International GPS Service for Geodynamics (IGS) is an organization which operates under the auspices of the International Association of Geodesy (IAG) and has been operational since January 1994. The primary objective of the IGS is to provide precise GPS data and data products to support geodetic and geophysical research activities.

A Comparative Study of the Precision of Carstens and Northern Digital Instruments Electromagnetic Articulographs

ERIC Educational Resources Information Center

Savariaux, Christophe; Badin, Pierre; Samson, Adeline; Gerber, Silvain

2017-01-01

Purpose: This study compares the precision of the electromagnetic articulographs used in speech research: Northern Digital Instruments' Wave and Carstens' AG200, AG500, and AG501 systems. Method: The fluctuation of distances between 3 pairs of sensors attached to a manually rotated device that can position them inside the measurement volumes was…

A fast high-precision six-degree-of-freedom relative position sensor

NASA Astrophysics Data System (ADS)

Hughes, Gary B.; Macasaet, Van P.; Griswold, Janelle; Sison, Claudia A.; Lubin, Philip; Meinhold, Peter; Suen, Jonathan; Brashears, Travis; Zhang, Qicheng; Madajian, Jonathan

2016-03-01

Lasers are commonly used in high-precision measurement and profiling systems. Some laser measurement systems are based on interferometry principles, and others are based on active triangulation, depending on requirements of the application. This paper describes an active triangulation laser measurement system for a specific application wherein the relative position of two fixed, rigid mechanical components is to be measured dynamically with high precision in six degrees of freedom (DOF). Potential applications include optical systems with feedback to control for mechanical vibration, such as target acquisition devices with multiple focal planes. The method uses an array of several laser emitters mounted on one component. The lasers are directed at a reflective surface on the second component. The reflective surface consists of a piecewise-planar pattern such as a pyramid, or more generally a curved reflective surface such as a hyperbolic paraboloid. The reflected spots are sensed at 2-dimensional photodiode arrays on the emitter component. Changes in the relative position of the emitter component and reflective surface will shift the location of the reflected spots within photodiode arrays. Relative motion in any degree of freedom produces independent shifts in the reflected spot locations, allowing full six-DOF relative position determination between the two component positions. Response time of the sensor is limited by the read-out rate of the photodiode arrays. Algorithms are given for position determination with limits on uncertainty and sensitivity, based on laser and spot-sensor characteristics, and assuming regular surfaces. Additional uncertainty analysis is achievable for surface irregularities based on calibration data.

Where is your arm? Variations in proprioception across space and tasks.

PubMed

Fuentes, Christina T; Bastian, Amy J

2010-01-01

The sense of limb position is crucial for movement control and environmental interactions. Our understanding of this fundamental proprioceptive process, however, is limited. For example, little is known about the accuracy of arm proprioception: Does it vary with changes in arm configuration, since some peripheral receptors are engaged only when joints move toward extreme angles? Are these variations consistent across different tasks? Does proprioceptive ability change depending on what we try to localize (e.g., fingertip position vs. elbow angle)? We used a robot exoskeleton to study proprioception in 14 arm configurations across three tasks, asking healthy subjects to 1) match a pointer to elbow angles after passive movements, 2) match a pointer to fingertip positions after passive movements, and 3) actively match their elbow angle to a pointer. Across all three tasks, subjects overestimated more extreme joint positions; this may be due to peripheral sensory signals biasing estimates as a safety mechanism to prevent injury. We also found that elbow angle estimates were more precise when used to judge fingertip position versus directly reported, suggesting that the brain has better access to limb endpoint position than joint angles. Finally, precision of elbow angle estimates improved in active versus passive movements, corroborating work showing that efference copies of motor commands and alpha-gamma motor neuron coactivation contribute to proprioceptive estimates. In sum, we have uncovered fundamental aspects of normal proprioceptive processing, demonstrating not only predictable biases that are dependent on joint configuration and independent of task but also improved precision when integrating information across joints.

Piezo-based motion stages for heavy duty operation in clean environments

NASA Astrophysics Data System (ADS)

Karasikov, Nir; Peled, Gal; Yasinov, Roman; Gissin, Michael; Feinstein, Alan

2018-02-01

A range of heavy duty, ultra-precise motion stages had been developed for precise positioning in semiconductor manufacturing and metrology, for use in a clean room and high vacuum (HV and UHV) environments, to meet the precision requirements for 7, 5 nm nodes and beyond. These stages are powered by L1B2 direct drive ultrasonic motors, which allows combining long motion range, sub-nanometer positioning accuracy, high stiffness (in the direction of motion), low power consumption and active compensation of thermal and structural drift while holding position. The mechanical design, material selection for clean room and high vacuum preparation techniques are reviewed. Test results in a clean room are reported for a two-axis (X-Y) stage, having a load capacity of 30 kg, a motion range of 450 mm, a positioning accuracy of < 1 nm, a maximum motion speed of > 200 mm/s and a < 2 nm position stability (3 sigma). Long term drift compensation to sub-nm level, against thermal drift, has been validated for more than 10 hours. Heavy duty operation in a high vacuum is exemplified via a single axis stage operating at 5E-7 Torr, having a moving mass of 0.96 kg, oriented against gravity. The stage is operated periodically (up and down) over a travel length of 45 mm. The motion profile has a trapezoidal shape with an acceleration of 1m/s2 and a constant velocity of 100 mm/s. The operational parameters (average absolute position error during constant velocity, motor force, dead zone level) remain stable over more than 370000 passes (experiment duration).

An automatic 2D–3D image matching method for reproducing spatial knee joint positions using single or dual fluoroscopic images

PubMed Central

Zhu, Zhonglin; Li, Guoan

2013-01-01

Fluoroscopic image technique, using either a single image or dual images, has been widely applied to measure in vivo human knee joint kinematics. However, few studies have compared the advantages of using single and dual fluoroscopic images. Furthermore, due to the size limitation of the image intensifiers, it is possible that only a portion of the knee joint could be captured by the fluoroscopy during dynamic knee joint motion. In this paper, we presented a systematic evaluation of an automatic 2D–3D image matching method in reproducing spatial knee joint positions using either single or dual fluoroscopic image techniques. The data indicated that for the femur and tibia, their spatial positions could be determined with an accuracy and precision less than 0.2 mm in translation and less than 0.4° in orientation when dual fluoroscopic images were used. Using single fluoroscopic images, the method could produce satisfactory accuracy in joint positions in the imaging plane (average up to 0.5 mm in translation and 1.3° in rotation), but large variations along the out-plane direction (in average up to 4.0 mm in translation and 2.28 in rotation). The precision of using single fluoroscopic images to determine the actual knee positions was worse than its accuracy obtained. The data also indicated that when using dual fluoroscopic image technique, if the knee joint outlines in one image were incomplete by 80%, the algorithm could still reproduce the joint positions with high precisions. PMID:21806411

A new method for precise determination of endograft position and apposition in the aortic neck after endovascular aortic aneurysm repair.

PubMed

VAN Noort, Kim; Schuurmann, Richte C; Slump, Cornelis H; Vos, Jan A; Devries, Jean P

2016-10-01

Follow-up imaging after endovascular aortic aneurysm repair (EVAR) focuses on detection of gross abnormalities: endoleaks and significant (>10 mm) migration. Precise determination of endograft position and wall apposition may predict late complications. We present a new measurement method to determine precise position and apposition of endografts in the aortic neck. Four patients were selected from our EVAR database. These patients had late (>1 year) type IA endoleak or >1 cm endograft migration. Twenty patients with uneventful follow-up were measured as controls. The new software adds six parameters to define endograft position and neck apposition: fabric distance to renal arteries, tilt, endograft expansion (% of the maximum original diameter), neck surface, apposition surface, and shortest apposition length. These parameters were determined on preoperative and all available postoperative CT-scans, to detect subtle changes during follow-up. All patients with endoleak or migration had increases in fabric distance, tilt, or endograft expansion or decrease of apposition surface. Changes occurred at least one CT scan before the endoleak or migration was noted in the CT reports. The patient without complications showed no changes in position or apposition during follow-up. The new measurement method detected subtle changes in endograft position and apposition during CT follow-up, not recognized initially. It can potentially determine endograft movements and decrease of apposition surface before they lead to complications like type IA endoleaks or uncorrectable migration. A larger follow-up study comparing complicated and non-complicated EVAR patients is needed to corroborate these results.

Flight evaluation of differential GPS aided inertial navigation systems

NASA Technical Reports Server (NTRS)

Mcnally, B. David; Paielli, Russell A.; Bach, Ralph E., Jr.; Warner, David N., Jr.

1992-01-01

Algorithms are described for integration of Differential Global Positioning System (DGPS) data with Inertial Navigation System (INS) data to provide an integrated DGPS/INS navigation system. The objective is to establish the benefits that can be achieved through various levels of integration of DGPS with INS for precision navigation. An eight state Kalman filter integration was implemented in real-time on a twin turbo-prop transport aircraft to evaluate system performance during terminal approach and landing operations. A fully integrated DGPS/INS system is also presented which models accelerometer and rate-gyro measurement errors plus position, velocity, and attitude errors. The fully integrated system was implemented off-line using range-domain (seventeen-state) and position domain (fifteen-state) Kalman filters. Both filter integration approaches were evaluated using data collected during the flight test. Flight-test data consisted of measurements from a 5 channel Precision Code GPS receiver, a strap-down Inertial Navigation Unit (INU), and GPS satellite differential range corrections from a ground reference station. The aircraft was laser tracked to determine its true position. Results indicate that there is no significant improvement in positioning accuracy with the higher levels of DGPS/INS integration. All three systems provided high-frequency (e.g., 20 Hz) estimates of position and velocity. The fully integrated system provided estimates of inertial sensor errors which may be used to improve INS navigation accuracy should GPS become unavailable, and improved estimates of acceleration, attitude, and body rates which can be used for guidance and control. Precision Code DGPS/INS positioning accuracy (root-mean-square) was 1.0 m cross-track and 3.0 m vertical. (This AGARDograph was sponsored by the Guidance and Control Panel.)

3D templating and patient-specific cutting guides (Knee-Plan) in total knee arthroplasty: postoperative CT-based assessment of implant positioning.

PubMed

Franceschi, J-P; Sbihi, A

2014-10-01

The precision of bone cuts and the positioning of components influence the functionality and longevity of total knee arthroplasty (TKA). The objective of this study was to evaluate the results of TKA, performed after 3D preoperative templating, with the prosthesis implanted using custom cutting guides (Knee-Plan system, Symbios Orthopédie SA). This prospective study investigated 107 TKAs. Three-dimensional preoperative templating was carried out on the surface views and CT views to analyze the deformation of the lower limb and plan the implantation. The components were positioned in an individualized manner to realign the lower limb and provide ligament balance based on bone landmarks. Final component positioning was analyzed in the three planes with a postoperative CT scan. The preoperative and 1 year follow-up IKS and WOMAC scores were collected and compared. All the cutting guides were stable and functional. Femoral component planning was reproduced with 0 ± 2 precision in the frontal plane (94%± 3), 2 ± 3 in the sagittal plane, and 0 ± 2 in the transverse plane. The precision of the tibial component was reproduced with 0 ± 2 precision in the frontal plane (93%± 3) and 0 ± 4 in the sagittal plane. The HKA angle increased from 177 ± 7 preoperatively to 180 ± 3 at 1 year of follow-up. The IKS and WOMAC scores were significantly improved at 1 year (P<0.0001). The Knee-Plan system can be a realistic, simple, and reliable alternative to conventional cutting guides and to computer-assisted surgery for TKA implantation. IV; prospective cohort study. Copyright © 2014. Published by Elsevier Masson SAS.

DPOD2014: a new DORIS extension of ITRF2014 for Precise Orbit Determination

NASA Astrophysics Data System (ADS)

Moreaux, G.; Willis, P.; Lemoine, F. G.; Zelensky, N. P.

2016-12-01

As one of the tracking systems used to determine orbits of the altimeter mission satellites (such as TOPEX/Poseidon, Envisat, Jason-1/2/3 & Cryosat-2), the position of the DORIS tracking stations provides a fundamental reference for the estimation of the precise orbits and so, by extension is fundamental for the quality of the altimeter data and derived products. Therefore, the time evolution of the position of both the existing and the newest DORIS stations must be precisely modeled and regularly updated. To satisfy operational requirements for precise orbit determination and routine delivery of geodetic products, the International DORIS Service maintains the so-called DPOD solutions, which can be seen as extensions of the latest available ITRF solution from the International Earth Rotation and Reference Systems Service (IERS). In mid-2016, the IDS agreed to change the processing strategy of the DPOD solution. The new solution from the IDS Combination Center (CC) consists of a DORIS cumulative position and velocity solution using the latest IDS combined weekly solutions. The first objective of this study is to describe the new DPOD elaboration scheme and to show the IDS CC internal validation steps. The second purpose is to present the external validation process made by an external team before the new DPOD is made available to all the users. The elaboration and validation procedures will be illustrated by the presentation of first version of the DPOD2014 (ITRF2014 DORIS extension) and focus will be given on the update of the position and velocity of two DORIS sites: Everest (after Gorkha earthquake M7.8 in April 2015) and Thule (Greenland).

Datum maintenance of the main Egyptian geodetic control networks by utilizing Precise Point Positioning "PPP" technique

NASA Astrophysics Data System (ADS)

Rabah, Mostafa; Elmewafey, Mahmoud; Farahan, Magda H.

2016-06-01

A geodetic control network is the wire-frame or the skeleton on which continuous and consistent mapping, Geographic Information Systems (GIS), and surveys are based. Traditionally, geodetic control points are established as permanent physical monuments placed in the ground and precisely marked, located, and documented. With the development of satellite surveying methods and their availability and high degree of accuracy, a geodetic control network could be established by using GNSS and referred to an international terrestrial reference frame used as a three-dimensional geocentric reference system for a country. Based on this concept, in 1992, the Egypt Survey Authority (ESA) established two networks, namely High Accuracy Reference Network (HARN) and the National Agricultural Cadastral Network (NACN). To transfer the International Terrestrial Reference Frame to the HARN, the HARN was connected with four IGS stations. The processing results were 1:10,000,000 (Order A) for HARN and 1:1,000,000 (Order B) for NACN relative network accuracy standard between stations defined in ITRF1994 Epoch1996. Since 1996, ESA did not perform any updating or maintaining works for these networks. To see how non-performing maintenance degrading the values of the HARN and NACN, the available HARN and NACN stations in the Nile Delta were observed. The Processing of the tested part was done by CSRS-PPP Service based on utilizing Precise Point Positioning "PPP" and Trimble Business Center "TBC". The study shows the feasibility of Precise Point Positioning in updating the absolute positioning of the HARN network and its role in updating the reference frame (ITRF). The study also confirmed the necessity of the absent role of datum maintenance of Egypt networks.

Bunch by bunch beam monitoring in 3rd and 4th generation light sources by means of single crystal diamond detectors and quantum well devices

NASA Astrophysics Data System (ADS)

Antonelli, M.; Di Fraia, M.; Tallaire, A.; Achard, J.; Carrato, S.; Menk, R. H.; Cautero, G.; Giuressi, D.; Jark, W. H.; Biasiol, G.; Ganbold, T.; Oliver, K.; Callegari, C.; Coreno, M.; De Sio, A.; Pace, E.

2012-10-01

New generation Synchrotron Radiation (SR) sources and Free Electron Lasers (FEL) require novel concepts of beam diagnostics to keep photon beams under surveillance, asking for simultaneous position and intensity monitoring. To deal with high power load and short time pulses provided by these sources, novel materials and methods are needed for the next generation BPMs. Diamond is a promising material for the production of semitransparent in situ X-ray BPMs withstanding the high dose rates of SR rings and high energy FELs. We report on the development of freestanding, single crystal CVD diamond detectors. Performances in both low and radio frequency SR beam monitoring are presented. For the former, sensitivity deviation was found to be approximately 2%; a 0.05% relative precision in the intensity measurements and a 0.1-μm precision in the position encoding have been estimated. For the latter, single-shot characterizations revealed sub-nanosecond rise-times and spatial precisions below 6 μm, which allowed bunch-by-bunch monitoring in multi-bunch operation. Preliminary measurements at the Fermi FEL have been performed with this detector, extracting quantitative intensity and position information for FEL pulses (~ 100 fs, energy 12 ÷ 60 eV), with a long-term spatial precision of about 85 μm results on FEL radiation damages are also reported. Due to their direct, low-energy band gap, InGaAs quantum well devices too may be used as fast detectors for photons ranging from visible to X-ray. Results are reported which show the capability of a novel InGaAs/InAlAs device to detect intensity and position of 100-fs-wide laser pulses.

Self-position estimation using terrain shadows for precise planetary landing

NASA Astrophysics Data System (ADS)

Kuga, Tomoki; Kojima, Hirohisa

2018-07-01

In recent years, the investigation of moons and planets has attracted increasing attention in several countries. Furthermore, recently developed landing systems are now expected to reach more scientifically interesting areas close to hazardous terrain, requiring precise landing capabilities within a 100 m range of the target point. To achieve this, terrain-relative navigation (capable of estimating the position of a lander relative to the target point on the ground surface is actively being studied as an effective method for achieving highly accurate landings. This paper proposes a self-position estimation method using shadows on the terrain based on edge extraction from image processing algorithms. The effectiveness of the proposed method is validated through numerical simulations using images generated from a digital elevation model of simulated terrains.

Precision gap particle separator

DOEpatents

Benett, William J.; Miles, Robin; Jones, II., Leslie M.; Stockton, Cheryl

2004-06-08

A system for separating particles entrained in a fluid includes a base with a first channel and a second channel. A precision gap connects the first channel and the second channel. The precision gap is of a size that allows small particles to pass from the first channel into the second channel and prevents large particles from the first channel into the second channel. A cover is positioned over the base unit, the first channel, the precision gap, and the second channel. An port directs the fluid containing the entrained particles into the first channel. An output port directs the large particles out of the first channel. A port connected to the second channel directs the small particles out of the second channel.

Quantum metrology of phase for accelerated two-level atom coupled with electromagnetic field with and without boundary

NASA Astrophysics Data System (ADS)

Yang, Ying; Liu, Xiaobao; Wang, Jieci; Jing, Jiliang

2018-03-01

We study how to improve the precision of the quantum estimation of phase for an uniformly accelerated atom in fluctuating electromagnetic field by reflecting boundaries. We find that the precision decreases with increases of the acceleration without the boundary. With the presence of a reflecting boundary, the precision depends on the atomic polarization, position and acceleration, which can be effectively enhanced compared to the case without boundary if we choose the appropriate conditions. In particular, with the presence of two parallel reflecting boundaries, we obtain the optimal precision for atomic parallel polarization and the special distance between two boundaries, as if the atom were shielded from the fluctuation.

The 22nd Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting

NASA Technical Reports Server (NTRS)

Sydnor, Richard L. (Editor)

1990-01-01

Papers presented at the 22nd Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting are compiled. The following subject areas are covered: Rb, Cs, and H-based frequency standards and cryogenic and trapped-ion technology; satellite laser tracking networks, GLONASS timing, intercomparison of national time scales and international telecommunications; telecommunications, power distribution, platform positioning, and geophysical survey industries; military communications and navigation systems; and dissemination of precise time and frequency by means of GPS, GLONASS, MILSTAR, LORAN, and synchronous communication satellites.

High precision detector robot arm system

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

Shu, Deming; Chu, Yong

A method and high precision robot arm system are provided, for example, for X-ray nanodiffraction with an X-ray nanoprobe. The robot arm system includes duo-vertical-stages and a kinematic linkage system. A two-dimensional (2D) vertical plane ultra-precision robot arm supporting an X-ray detector provides positioning and manipulating of the X-ray detector. A vertical support for the 2D vertical plane robot arm includes spaced apart rails respectively engaging a first bearing structure and a second bearing structure carried by the 2D vertical plane robot arm.

Evaluating a campaign GNSS velocity field derived from an online precise point positioning service

NASA Astrophysics Data System (ADS)

Holden, L.; Silcock, D.; Choy, S.; Cas, R.; Ailleres, L.; Fournier, N.

2017-01-01

Traditional processing of Global Navigation Satellite System (GNSS) data using dedicated scientific software has provided the highest levels of positional accuracy, and has been used extensively in geophysical deformation studies. To achieve these accuracies a significant level of understanding and training is required, limiting their availability to the general scientific community. Various online GNSS processing services, now freely available, address some of these difficulties and allow users to easily process their own GNSS data and potentially obtain high quality results. Previous research into these services has focused on Continually Operating Reference Station (CORS) GNSS data. Less research exists on the results achievable with these services using large campaign GNSS data sets, which are inherently noisier than CORS data. Even less research exists on the quality of velocity fields derived from campaign GNSS data processed through online precise point positioning services. Particularly, whether they are suitable for geodynamic and deformation studies where precise and reliable velocities are needed. In this research, we process a very large campaign GPS data set (spanning 10 yr) with the online Jet Propulsion Laboratory Automated Precise Positioning Service. This data set is taken from a GNSS network specifically designed and surveyed to measure deformation through the central North Island of New Zealand. This includes regional CORS stations. We then use these coordinates to derive a horizontal and vertical velocity field. This is the first time that a large campaign GPS data set has been processed solely using an online service and the solutions used to determine a horizontal and vertical velocity field. We compared this velocity field to that of another well utilized GNSS scientific software package. The results show a good agreement between the CORS positions and campaign station velocities obtained from the two approaches. We discuss the implications of these results for how future GNSS campaign field surveys might be conducted and how their data might be processed.

Cyclic Voltammetry Probe Approach Curves with Alkali Amalgams at Mercury Sphere-Cap Scanning Electrochemical Microscopy Probes.

PubMed

Barton, Zachary J; Rodríguez-López, Joaquín

2017-03-07

We report a method of precisely positioning a Hg-based ultramicroelectrode (UME) for scanning electrochemical microscopy (SECM) investigations of any substrate. Hg-based probes are capable of performing amalgamation reactions with metal cations, which avoid unwanted side reactions and positive feedback mechanisms that can prove problematic for traditional probe positioning methods. However, prolonged collection of ions eventually leads to saturation of the amalgam accompanied by irreversible loss of Hg. In order to obtain negative feedback positioning control without risking damage to the SECM probe, we implement cyclic voltammetry probe approach surfaces (CV-PASs), consisting of CVs performed between incremental motor movements. The amalgamation current, peak stripping current, and integrated stripping charge extracted from a shared CV-PAS give three distinct probe approach curves (CV-PACs), which can be used to determine the tip-substrate gap to within 1% of the probe radius. Using finite element simulations, we establish a new protocol for fitting any CV-PAC and demonstrate its validity with experimental results for sodium and potassium ions in propylene carbonate by obtaining over 3 orders of magnitude greater accuracy and more than 20-fold greater precision than existing methods. Considering the timescales of diffusion and amalgam saturation, we also present limiting conditions for obtaining and fitting CV-PAC data. The ion-specific signals isolated in CV-PACs allow precise and accurate positioning of Hg-based SECM probes over any sample and enable the deployment of CV-PAS SECM as an analytical tool for traditionally challenging conditions.

WE-AB-BRB-12: Nanoscintillator Fiber-Optic Detector System for Microbeam Radiation Therapy Dosimetry

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

Rivera, J; Dooley, J; Chang, S

2015-06-15

Purpose: Microbeam Radiation Therapy (MRT) is an experimental radiation therapy that has demonstrated a higher therapeutic ratio than conventional radiation therapy in animal studies. There are several roadblocks in translating the promising treatment technology to clinical application, one of which is the lack of a real-time, high-resolution dosimeter. Current clinical radiation detectors have poor spatial resolution and, as such, are unsuitable for measuring microbeams with submillimeter-scale widths. Although GafChromic film has high spatial resolution, it lacks the real-time dosimetry capability necessary for MRT preclinical research and potential clinical use. In this work we have demonstrated the feasibility of using amore » nanoscintillator fiber-optic detector (nanoFOD) system for real-time MRT dosimetry. Methods: A microplanar beam array is generated using a x-ray research irradiator and a custom-made, microbeam-forming collimator. The newest generation nanoFOD has an effective size of 70 µm in the measurement direction and was calibrated against a kV ion chamber (RadCal Accu-Pro) in open field geometry. We have written a computer script that performs automatic data collection with immediate background subtraction. A computer-controlled detector positioning stage is used to precisely measure the microbeam peak dose and beam profile by translating the stage during data collection. We test the new generation nanoFOD system, with increased active scintillation volume, against the previous generation system. Both raw and processed data are time-stamped and recorded to enable future post-processing. Results: The real-time microbeam dosimetry system worked as expected. The new generation dosimeter has approximately double the active volume compared to the previous generation resulting in over 900% increase in signal. The active volume of the dosimeter still provided the spatial resolution that meets the Nyquist criterion for our microbeam widths. Conclusion: We have demonstrated that real-time dosimetry of MRT microbeams is feasible using a nanoscintillator fiber-optic detector with integrated positioning system.« less

[Concept of living conditions or social strata?--which approach is more suitable for describing unhealthy living circumstances of mothers?].

PubMed

Sperlich, S; Geyer, S

2010-11-01

The aim of this study was to identify living conditions associated with elevated health risks for mothers. Following up the debate on appropriate characterisation of social structure in modern societies, two different approaches, namely the 'social strata concept' and the 'concept of living conditions', were considered. Of particular interest was the question if the concept of living conditions, which is based on a broader definition of social status, allowed a more precise description of health-related living circumstances. The study was based on clinical data from 6,094 inpatients in Mother-Child rehabilitation centres in Germany. Taking socioeconomic status, household characteristics and psychosocial stressors into account seven typical living conditions of mothers could be identified by cluster analysis. Social status was measured by the Winkler Index. A moderate health-related gradient of increasing health risks with decreasing social position could be found for psychological and bodily disabilities. The approach of living conditions revealed that two living circumstances of mothers could be identified as being related to extremely poor health. These are i) dissatisfied single mothers with high degrees of psychosocial distress and lack of social support, and ii) married mothers with conflicts within the family and self-perceived lack of appreciation. Different from these findings, a pronounced social gradient could be found for overweight and smoking. Here the concept of social strata revealed in part excessive risks compared to the concept of living conditions. Overall, the integration of further social determinants allowed a more detailed insight into health-related living conditions, which are not solely determined by socioeconomic position. A global answer about the adequacy of the 'social strata concept' versus 'concept of living conditions' for identifying unhealthy living conditions could not be given because the relevance of both conceptual frameworks depended on the health outcomes considered. © Georg Thieme Verlag KG Stuttgart · New York.

Cobalt: Development and Maturation of GN&C Technologies for Precision Landing

NASA Technical Reports Server (NTRS)

Carson, John M.; Restrepo, Carolina; Seubert, Carl; Amzajerdian, Farzin

2016-01-01

The CoOperative Blending of Autonomous Landing Technologies (COBALT) instrument is a terrestrial test platform for development and maturation of guidance, navigation and control (GN&C) technologies for precision landing. The project is developing a third-generation Langley Research Center (LaRC) navigation doppler lidar (NDL) for ultra-precise velocity and range measurements, which will be integrated and tested with the Jet Propulsion Laboratory (JPL) lander vision system (LVS) for terrain relative navigation (TRN) position estimates. These technologies together provide precise navigation knowledge that is critical for a controlled and precise touchdown. The COBALT hardware will be integrated in 2017 into the GN&C subsystem of the Xodiac rocket-propulsive vertical test bed (VTB) developed by Masten Space Systems, and two terrestrial flight campaigns will be conducted: one open-loop (i.e., passive) and one closed-loop (i.e., active).

Modeling and Implementation of Multi-Position Non-Continuous Rotation Gyroscope North Finder.

PubMed

Luo, Jun; Wang, Zhiqian; Shen, Chengwu; Kuijper, Arjan; Wen, Zhuoman; Liu, Shaojin

2016-09-20

Even when the Global Positioning System (GPS) signal is blocked, a rate gyroscope (gyro) north finder is capable of providing the required azimuth reference information to a certain extent. In order to measure the azimuth between the observer and the north direction very accurately, we propose a multi-position non-continuous rotation gyro north finding scheme. Our new generalized mathematical model analyzes the elements that affect the azimuth measurement precision and can thus provide high precision azimuth reference information. Based on the gyro's principle of detecting a projection of the earth rotation rate on its sensitive axis and the proposed north finding scheme, we are able to deduct an accurate mathematical model of the gyro outputs against azimuth with the gyro and shaft misalignments. Combining the gyro outputs model and the theory of propagation of uncertainty, some approaches to optimize north finding are provided, including reducing the gyro bias error, constraining the gyro random error, increasing the number of rotation points, improving rotation angle measurement precision, decreasing the gyro and the shaft misalignment angles. According them, a north finder setup is built and the azimuth uncertainty of 18" is obtained. This paper provides systematic theory for analyzing the details of the gyro north finder scheme from simulation to implementation. The proposed theory can guide both applied researchers in academia and advanced practitioners in industry for designing high precision robust north finder based on different types of rate gyroscopes.

GNSS Wave Glider: First results from Loch Ness and demonstration of its suitability for determining the marine geoid

NASA Astrophysics Data System (ADS)

Penna, N. T.; Morales Maqueda, M.; Williams, S. D.; Foden, P.; Martin, I.; Pugh, J.

2013-12-01

We report on a first deployment of a GNSS Wave Glider designed for precise, unmanned, autonomous, mobile self-propelled sea level and sea state measurement in the open ocean. The Wave Glider, equipped with a dual frequency GPS+GLONASS receiver, was deployed in Loch Ness, Scotland, autonomously travelling 32 km in a north-easterly direction along the length of the loch in 26 hours, propelled by energy generated from waves of typical amplitude only 100-150 mm and frequency on the order 0.5-1 Hz. The Wave Glider GNSS data were analysed using a post-processed kinematic GPS+GLONASS precise point positioning (PPP) approach, which were quality controlled using double difference GPS kinematic processing with respect to onshore reference stations at either end of the loch. The PPP heights of the loch's surface revealed a clear geoid gradient of about 30 mm/km (i.e. just under 1 m over the whole length of the loch), very similar to both the EGM2008 and OSGM02 geoid models, demonstrating the potential use of a GNSS Wave Glider for marine geoid determination. After applying a low pass filter, the GNSS heights showed local deviations from both EGM2008 and OSGM02, potentially caused by omission errors or a lack of gravity data over Loch Ness. In addition to dual frequency GNSS data, the Wave Glider also recorded inclinometer data, bathymetry, and surface currents, which, in combination with tide gauge and wind data, were used to further control and interpret the GNSS time series.

Shape-specific nanostructured protein mimics from de novo designed chimeric peptides.

PubMed

Jiang, Linhai; Yang, Su; Lund, Reidar; Dong, He

2018-01-30

Natural proteins self-assemble into highly-ordered nanoscaled architectures to perform specific functions. The intricate functions of proteins have provided great impetus for researchers to develop strategies for designing and engineering synthetic nanostructures as protein mimics. Compared to the success in engineering fibrous protein mimetics, the design of discrete globular protein-like nanostructures has been challenging mainly due to the lack of precise control over geometric packing and intermolecular interactions among synthetic building blocks. In this contribution, we report an effective strategy to construct shape-specific nanostructures based on the self-assembly of chimeric peptides consisting of a coiled coil dimer and a collagen triple helix folding motif. Under salt-free conditions, we showed spontaneous self-assembly of the chimeric peptides into monodisperse, trigonal bipyramidal-like nanoparticles with precise control over the stoichiometry of two folding motifs and the geometrical arrangements relative to one another. Three coiled coil dimers are interdigitated on the equatorial plane while the two collagen triple helices are located in the axial position, perpendicular to the coiled coil plane. A detailed molecular model was proposed and further validated by small angle X-ray scattering experiments and molecular dynamics (MD) simulation. The results from this study indicated that the molecular folding of each motif within the chimeric peptides and their geometric packing played important roles in the formation of discrete protein-like nanoparticles. The peptide design and self-assembly mechanism may open up new routes for the construction of highly organized, discrete self-assembling protein-like nanostructures with greater levels of control over assembly accuracy.

Contribution of the 40Ar/39Ar method to improve Middle-Pleistocene archaeological/palaeontological sites from the Italian Peninsula

NASA Astrophysics Data System (ADS)

Nomade, Sebastien, ,, Dr.; Pereira, MSc. Alison; voinchet, Pierre, ,, Dr.; Bahain, Jean-Jacques, ,, Dr.; Aureli, Daniele, ,, Dr.; Arzarello, Marta, ,, Dr.; Anzidei, Anna-Paola, ,, Dr.; Biddittu, Italo, ,, Dr.; Bulgarelli, Maria-Grazia, ,, Dr.; Falguères, Christophe, ,, Dr.; Giaccio, Biagio, ,, Dr.; Guillou, Hervé, ,, Dr.; Manzi, Gorgio, ,, Dr.; Moncel, Marie-Hélène, ,, Dr.; Nicoud, Elisa, ,, Dr.; Pagli, Maria, ,, Dr.; Parenti, Fabio, ,, Dr.; Peretto, Carlo, ,, Dr.; Piperno, Marcello, ,, Dr.; Rocca, Roxane, ,, Dr.

2017-04-01

European Middle-Pleistocene archaeological and/or paleontological sites lack a unified and precise chronological framework. Despite recent efforts mostly focused on methods such as OSL, ESR/U-series or cosmogenic nuclides, the age of numerous sites from this period fundamentally still relies on qualitative and speculative palaeoenvironmental and/or palaeontological/palaeoanthropological considerations. The lack of robust chronologies, along with the scarcity of human fossils, prevent coherent correlations between European sites which in turn limits our understanding of human diffusion dynamics, understand techno-cultural evolution or correlate archaeological sites with palaeoclimatic and environmental records. With the goal of providing an accurate and precise chronological framework based on a multi-method approach, a research network including geochronologists, archaeologist and paleoanthropologists from various French and Italian institutions launched in 2010 a wide study of Middle-Pleistocene archaeological sites of central and southern Italy. This study combining the 39Ar/40Ar method with palaeo-dosimetric methods applied to European sites in the age range of 700 ka to 300 ka is unprecedented. In parallel, a large effort has been done to improve the regional Middle-Pleistocene tephrostratigraphic database through a massive application of both high-precision 40Ar/39Ar geochronological and geochemical investigations. We illustrate our approach and results in addressing several key-sites such as Notarchirico, Valle Giumentina; Ceprano-Campogrande and La Polledrara di Cecanibbio. The accurate and precise chronological framework we built permits us to replace all the investigated archaeological and palaeontological records into a coherent climatic and environmental context. Furthermore, our work provides the opportunity to compare lithic industries from a technical and evolutionary point of view within a homogeneous temporal frame. These preliminary results border the current limitations of the 40Ar/39Ar method and will guide expected advances to apply our approach to other European sites.

Large format focal plane array integration with precision alignment, metrology and accuracy capabilities

NASA Astrophysics Data System (ADS)

Neumann, Jay; Parlato, Russell; Tracy, Gregory; Randolph, Max

2015-09-01

Focal plane alignment for large format arrays and faster optical systems require enhanced precision methodology and stability over temperature. The increase in focal plane array size continues to drive the alignment capability. Depending on the optical system, the focal plane flatness of less than 25μm (.001") is required over transition temperatures from ambient to cooled operating temperatures. The focal plane flatness requirement must also be maintained in airborne or launch vibration environments. This paper addresses the challenge of the detector integration into the focal plane module and housing assemblies, the methodology to reduce error terms during integration and the evaluation of thermal effects. The driving factors influencing the alignment accuracy include: datum transfers, material effects over temperature, alignment stability over test, adjustment precision and traceability to NIST standard. The FPA module design and alignment methodology reduces the error terms by minimizing the measurement transfers to the housing. In the design, the proper material selection requires matched coefficient of expansion materials minimizes both the physical shift over temperature as well as lowering the stress induced into the detector. When required, the co-registration of focal planes and filters can achieve submicron relative positioning by applying precision equipment, interferometry and piezoelectric positioning stages. All measurements and characterizations maintain traceability to NIST standards. The metrology characterizes the equipment's accuracy, repeatability and precision of the measurements.

Immunolocalization of choline acetyltransferase of common type in the central brain mass of Octopus vulgaris

PubMed Central

Casini, A.; Vaccaro, R.; D'Este, L.; Sakaue, Y.; Bellier, J.P.; Kimura, H.; Renda, T.G.

2012-01-01

Acetylcholine, the first neurotransmitter to be identified in the vertebrate frog, is widely distributed among the animal kingdom. The presence of a large amount of acetylcholine in the nervous system of cephalopods is well known from several biochemical and physiological studies. However, little is known about the precise distribution of cholinergic structures due to a lack of a suitable histochemical technique for detecting acetylcholine. The most reliable method to visualize the cholinergic neurons is the immunohistochemical localization of the enzyme choline acetyltransferase, the synthetic enzyme of acetylcholine. Following our previous study on the distribution patterns of cholinergic neurons in the Octopus vulgaris visual system, using a novel antibody that recognizes choline acetyltransferase of the common type (cChAT), now we extend our investigation on the octopus central brain mass. When applied on sections of octopus central ganglia, immunoreactivity for cChAT was detected in cell bodies of all central brain mass lobes with the notable exception of the subfrontal and subvertical lobes. Positive varicosed nerves fibers where observed in the neuropil of all central brain mass lobes. PMID:23027350

Immunolocalization of choline acetyltransferase of common type in the central brain mass of Octopus vulgaris.

PubMed

Casini, A; Vaccaro, R; D'Este, L; Sakaue, Y; Bellier, J P; Kimura, H; Renda, T G

2012-07-19

Acetylcholine, the first neurotransmitter to be identified in the vertebrate frog, is widely distributed among the animal kingdom. The presence of a large amount of acetylcholine in the nervous system of cephalopods is well known from several biochemical and physiological studies. However, little is known about the precise distribution of cholinergic structures due to a lack of a suitable histochemical technique for detecting acetylcholine. The most reliable method to visualize the cholinergic neurons is the immunohistochemical localization of the enzyme choline acetyltransferase, the synthetic enzyme of acetylcholine. Following our previous study on the distribution patterns of cholinergic neurons in the Octopus vulgaris visual system, using a novel antibody that recognizes choline acetyltransferase of the common type (cChAT), now we extend our investigation on the octopus central brain mass. When applied on sections of octopus central ganglia, immunoreactivity for cChAT was detected in cell bodies of all central brain mass lobes with the notable exception of the subfrontal and subvertical lobes. Positive varicosed nerves fibers where observed in the neuropil of all central brain mass lobes.

Quantification of menadione from plasma and urine by a novel cysteamine-derivatization based UPLC-MS/MS method.

PubMed

Yuan, Teng-Fei; Wang, Shao-Ting; Li, Yan

2017-09-15

Menadione, as the crucial component of vitamin Ks, possessed significant nutritional and clinical values. However, there was still lack of favourable quantification strategies for it to date. For improvement, a novel cysteamine derivatization based UPLC-MS/MS method was presented in this work. The derivatizating reaction was proved non-toxic, easy-handling and high-efficient, which realized the MS detection of menadione under positive mode. Benefitting from the excellent sensitivity of the derivatizating product as well as the introduction of the stable isotope dilution technique, the quantification could be achieved in the range of 0.05-50.0ng/mL for plasma and urine matrixes with satisfied accuracy and precision. After analysis of the samples from healthy volunteers after oral administration of menadione sodium bisulfite tablets, the urinary free menadione was quantified for the very first time. We believe the progress in this work could largely promote the exploration of the metabolic mechanism of vitamin K in vivo. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimization of tissue physical parameters for accurate temperature estimation from finite-element simulation of radiofrequency ablation.

PubMed

Subramanian, Swetha; Mast, T Douglas

2015-10-07

Computational finite element models are commonly used for the simulation of radiofrequency ablation (RFA) treatments. However, the accuracy of these simulations is limited by the lack of precise knowledge of tissue parameters. In this technical note, an inverse solver based on the unscented Kalman filter (UKF) is proposed to optimize values for specific heat, thermal conductivity, and electrical conductivity resulting in accurately simulated temperature elevations. A total of 15 RFA treatments were performed on ex vivo bovine liver tissue. For each RFA treatment, 15 finite-element simulations were performed using a set of deterministically chosen tissue parameters to estimate the mean and variance of the resulting tissue ablation. The UKF was implemented as an inverse solver to recover the specific heat, thermal conductivity, and electrical conductivity corresponding to the measured area of the ablated tissue region, as determined from gross tissue histology. These tissue parameters were then employed in the finite element model to simulate the position- and time-dependent tissue temperature. Results show good agreement between simulated and measured temperature.

Systems consolidation revisited, but not revised: The promise and limits of optogenetics in the study of memory.

PubMed

Hardt, Oliver; Nadel, Lynn

2017-12-05

Episodic memories (in humans) and event-like memories (in non-human animals) require the hippocampus for some time after acquisition, but at remote points seem to depend more on cortical areas instead. Systems consolidation refers to the process that promotes this reorganization of memory. Various theoretical frameworks accounting for this process have been proposed, but clear evidence favoring one or another of these positions has been lacking. Addressing this issue, a recent study deployed some of the most advanced neurobiological technologies - optogenetics and calcium imaging - and provided high resolution, precise observations regarding brain systems involved in recent and remote contextual fear memories. We critically review these findings within their historical context and conclude that they do not resolve the debate concerning systems consolidation. This is because the relevant question concerning the quality of memory at recent and remote time points has not been answered: Does the memory reorganization taking place during systems consolidation result in changes to the content of memory? Copyright © 2017 Elsevier B.V. All rights reserved.

Veselago focusing of anisotropic massless Dirac fermions

NASA Astrophysics Data System (ADS)

Zhang, Shu-Hui; Yang, Wen; Peeters, F. M.

2018-05-01

Massless Dirac fermions (MDFs) emerge as quasiparticles in various novel materials such as graphene and topological insulators, and they exhibit several intriguing properties, of which Veselago focusing is an outstanding example with a lot of possible applications. However, up to now Veselago focusing merely occurred in p-n junction devices based on the isotropic MDF, which lacks the tunability needed for realistic applications. Here, motivated by the emergence of novel Dirac materials, we investigate the propagation behaviors of anisotropic MDFs in such a p-n junction structure. By projecting the Hamiltonian of the anisotropic MDF to that of the isotropic MDF and deriving an exact analytical expression for the propagator, precise Veselago focusing is demonstrated without the need for mirror symmetry of the electron source and its focusing image. We show a tunable focusing position that can be used in a device to probe masked atom-scale defects. This study provides an innovative concept to realize Veselago focusing relevant for potential applications, and it paves the way for the design of novel electron optics devices by exploiting the anisotropic MDF.

Thyroid Carcinoma

PubMed

Ahmed, Najeeb; Niyaz, Kashif; Borakati, Aditya; Marafi, Fahad; Birk, Rubinder; Usmani, Sharjeel

2018-02-26

Differentiated thyroid cancer (DTC) has a good prognosis overall; however, lifelong follow-up is required for many cases. Radioiodine planar imaging with iodine-123 (I-123) or radioiodine-131 (I-131) remains the standard in the follow-up after initial surgery and ablation of residual thyroid tissue using I-131 therapy. Radioiodine imaging is also used in risk-stratifying and for staging of thyroid cancer, and in long-term follow-up. Unfortunately, the lack of anatomical detail on planar gamma camera imaging and superimposition of areas presenting with increased radioiodine uptake can make accurate diagnosis and localization of radioiodine-avid metastatic disease challenging, leading to false positive results and potentially to over-treatment of patients. Hybrid SPECT/CT allows precise anatomical localization and superior characterization of foci of increased tracer uptake when compared to planar imaging. This, in turn, allows the differentiation of pathological and physiological uptake, increasing the accuracy of image interpretation and ultimately improving the accuracy of DTC staging and subsequent patient management. In this review, we look at the unique and emerging role that SPECT/CT plays in the management of DTC, illustrated by examples from our own clinical practice. Creative Commons Attribution License

Wellbeing in the aftermath of floods.

PubMed

Walker-Springett, Kate; Butler, Catherine; Adger, W Neil

2017-01-01

The interactions between flood events, their aftermath, and recovery leading to health and wellbeing outcomes for individuals are complex, and the pathways and mechanisms through which wellbeing is affected are often hidden and remain under-researched. This study analyses the diverse processes that explain changes in wellbeing for those experiencing flooding. It identifies key pathways to wellbeing outcomes that concern perceptions of lack of agency, dislocation from home, and disrupted futures inducing negative impacts, with offsetting positive effects through community networks and interactions. The mixed method study is based on data from repeated qualitative semi-structured interviews (n=60) and a structured survey (n=1000) with individuals that experienced flooding directly during winter 2013/14 in two UK regions. The results show for the first time the diversity and intersection of pathways to wellbeing outcomes in the aftermath of floods. The findings suggest that enhanced public health planning and interventions could focus on the precise practices and mechanisms that intersect to produce anxiety, stress, and their amelioration at individual and community levels. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

mRNA Traffic Control Reviewed: N6-Methyladenosine (m6 A) Takes the Driver's Seat.

PubMed

Visvanathan, Abhirami; Somasundaram, Kumaravel

2018-01-01

Messenger RNA is a flexible tool box that plays a key role in the dynamic regulation of gene expression. RNA modifications variegate the message conveyed by the mRNA. Similar to DNA and histone modifications, mRNA modifications are reversible and play a key role in the regulation of molecular events. Our understanding about the landscape of RNA modifications is still rudimentary in contrast to DNA and histone modifications. The major obstacle has been the lack of sensitive detection methods since they are non-editing events. However, with the advent of next-generation sequencing techniques, RNA modifications are being identified precisely at single nucleotide resolution. In recent years, methylation at the N6 position of adenine (m 6 A) has gained the attention of RNA biologists. The m 6 A modification has a set of writers (methylases), erasers (demethylases), and readers. Here, we provide a summary of interesting facts, conflicting findings, and recent advances in the technical and functional aspects of the m 6 A epitranscriptome. © 2017 WILEY Periodicals, Inc.

Integrative analysis with ChIP-seq advances the limits of transcript quantification from RNA-seq

PubMed Central

Liu, Peng; Sanalkumar, Rajendran; Bresnick, Emery H.; Keleş, Sündüz; Dewey, Colin N.

2016-01-01

RNA-seq is currently the technology of choice for global measurement of transcript abundances in cells. Despite its successes, isoform-level quantification remains difficult because short RNA-seq reads are often compatible with multiple alternatively spliced isoforms. Existing methods rely heavily on uniquely mapping reads, which are not available for numerous isoforms that lack regions of unique sequence. To improve quantification accuracy in such difficult cases, we developed a novel computational method, prior-enhanced RSEM (pRSEM), which uses a complementary data type in addition to RNA-seq data. We found that ChIP-seq data of RNA polymerase II and histone modifications were particularly informative in this approach. In qRT-PCR validations, pRSEM was shown to be superior than competing methods in estimating relative isoform abundances within or across conditions. Data-driven simulations suggested that pRSEM has a greatly decreased false-positive rate at the expense of a small increase in false-negative rate. In aggregate, our study demonstrates that pRSEM transforms existing capacity to precisely estimate transcript abundances, especially at the isoform level. PMID:27405803

Medical error and related factors during internship and residency.

PubMed

Ahmadipour, Habibeh; Nahid, Mortazavi

2015-01-01

It is difficult to determine the real incidence of medical errors due to the lack of a precise definition of errors, as well as the failure to report them under certain circumstances. We carried out a cross- sectional study in Kerman University of Medical Sciences, Iran in 2013. The participants were selected through the census method. The data were collected using a self-administered questionnaire, which consisted of questions on the participants' demographic data and questions on the medical errors committed. The data were analysed by SPSS 19. It was found that 270 participants had committed medical errors. There was no significant difference in the frequency of errors committed by interns and residents. In the case of residents, the most common error was misdiagnosis and in that of interns, errors related to history-taking and physical examination. Considering that medical errors are common in the clinical setting, the education system should train interns and residents to prevent the occurrence of errors. In addition, the system should develop a positive attitude among them so that they can deal better with medical errors.

Human-arm-and-hand-dynamic model with variability analyses for a stylus-based haptic interface.

PubMed

Fu, Michael J; Cavuşoğlu, M Cenk

2012-12-01

Haptic interface research benefits from accurate human arm models for control and system design. The literature contains many human arm dynamic models but lacks detailed variability analyses. Without accurate measurements, variability is modeled in a very conservative manner, leading to less than optimal controller and system designs. This paper not only presents models for human arm dynamics but also develops inter- and intrasubject variability models for a stylus-based haptic device. Data from 15 human subjects (nine male, six female, ages 20-32) were collected using a Phantom Premium 1.5a haptic device for system identification. In this paper, grip-force-dependent models were identified for 1-3-N grip forces in the three spatial axes. Also, variability due to human subjects and grip-force variation were modeled as both structured and unstructured uncertainties. For both forms of variability, the maximum variation, 95 %, and 67 % confidence interval limits were examined. All models were in the frequency domain with force as input and position as output. The identified models enable precise controllers targeted to a subset of possible human operator dynamics.

Dodecahedral space topology as an explanation for weak wide-angle temperature correlations in the cosmic microwave background.

PubMed

Luminet, Jean-Pierre; Weeks, Jeffrey R; Riazuelo, Alain; Lehoucq, Roland; Uzan, Jean-Philippe

2003-10-09

The current 'standard model' of cosmology posits an infinite flat universe forever expanding under the pressure of dark energy. First-year data from the Wilkinson Microwave Anisotropy Probe (WMAP) confirm this model to spectacular precision on all but the largest scales. Temperature correlations across the microwave sky match expectations on angular scales narrower than 60 degrees but, contrary to predictions, vanish on scales wider than 60 degrees. Several explanations have been proposed. One natural approach questions the underlying geometry of space--namely, its curvature and topology. In an infinite flat space, waves from the Big Bang would fill the universe on all length scales. The observed lack of temperature correlations on scales beyond 60 degrees means that the broadest waves are missing, perhaps because space itself is not big enough to support them. Here we present a simple geometrical model of a finite space--the Poincaré dodecahedral space--which accounts for WMAP's observations with no fine-tuning required. The predicted density is Omega(0) approximately 1.013 > 1, and the model also predicts temperature correlations in matching circles on the sky.

Efficient GPS Position Determination Algorithms

DTIC Science & Technology

2007-06-01

provides two types of services. The Standard Positioning Service (SPS) is designated for the civilian users. The Precise Positioning Service (PPS) is...meters RMS. Military receivers utilized de -encryption techniques to remove SA and provide position accuracy of 10-meters root-mean-square (RMS) [1...difficulties. This type of scenario can be expected in test range applications ([20] and [21]). In this dissertation, the experimental test environment

Real-time, autonomous precise satellite orbit determination using the global positioning system

NASA Astrophysics Data System (ADS)

Goldstein, David Ben

2000-10-01

The desire for autonomously generated, rapidly available, and highly accurate satellite ephemeris is growing with the proliferation of constellations of satellites and the cost and overhead of ground tracking resources. Autonomous Orbit Determination (OD) may be done on the ground in a post-processing mode or in real-time on board a satellite and may be accomplished days, hours or immediately after observations are processed. The Global Positioning System (GPS) is now widely used as an alternative to ground tracking resources to supply observation data for satellite positioning and navigation. GPS is accurate, inexpensive, provides continuous coverage, and is an excellent choice for autonomous systems. In an effort to estimate precise satellite ephemeris in real-time on board a satellite, the Goddard Space Flight Center (GSFC) created the GPS Enhanced OD Experiment (GEODE) flight navigation software. This dissertation offers alternative methods and improvements to GEODE to increase on board autonomy and real-time total position accuracy and precision without increasing computational burden. First, GEODE is modified to include a Gravity Acceleration Approximation Function (GAAF) to replace the traditional spherical harmonic representation of the gravity field. Next, an ionospheric correction method called Differenced Range Versus Integrated Doppler (DRVID) is applied to correct for ionospheric errors in the GPS measurements used in GEODE. Then, Dynamic Model Compensation (DMC) is added to estimate unmodeled and/or mismodeled forces in the dynamic model and to provide an alternative process noise variance-covariance formulation. Finally, a Genetic Algorithm (GA) is implemented in the form of Genetic Model Compensation (GMC) to optimize DMC forcing noise parameters. Application of GAAF, DRVID and DMC improved GEODE's position estimates by 28.3% when applied to GPS/MET data collected in the presence of Selective Availability (SA), 17.5% when SA is removed from the GPS/MET data and 10.8% on SA free TOPEX data. Position estimates with RSS errors below I meter are now achieved using SA free TOPEX data. DRVID causes an increase in computational burden while GAAF and DMC reduce computational burden. The net effect of applying GAAF, DRVID and DMC is an improvement in GEODE's accuracy/precision without an increase in computational burden.

a Precise, Low-Cost Rtk Gnss System for Uav Applications

NASA Astrophysics Data System (ADS)

Stempfhuber, W.; Buchholz, M.

2011-09-01

High accuracy with real-time positioning of moving objects has been considered a standard task of engineering geodesy for 10 to 15 years. An absolute positioning accuracy of 1-3 cm is generally possible worldwide and is further used in many areas of machine guidance (machine control and guidance), and farming (precision farming) as well as for various special applications (e.g. railway trolley, mining, etc.). The cost of the measuring instruments required for the use of geodetic L1/L2 receivers with a local reference station amounts to approximately USD 30,000 to 50,000. Therefore, dual frequency RTK GNSS receivers are not used in the mass market. Affordable GPS/GNSS modules have already reached the mass market in various areas such as mobile phones, car navigation, the leisure industry, etc. Kinematic real-time positioning applications with centimetre or decimetre levels could also evolve into a mass product. In order for this to happen, the costs for such systems must lie between USD 1,000 to 2,000. What exactly low-cost means is determined by the precise specifications of the given individual application. Several university studies in geodesy focus on the approach of high-accuracy positioning by means of single frequency receivers for static applications [e.g. GLABSCH et. al. 2009, SCHWIEGER and GLÄSER 2005, ALKAN 2010, REALINI et. al. 2010, KORTH and HOFMANN 2011]. Although intelligent approaches have been developed that compute a trajectory in the post-processing mode [REALINI et. al., 2010], at present, there are only a very few GNSS Low-Cost Systems that enable real-time processing. This approach to precise position determination by means of the computation of static raw data with single frequency receivers is currently being explored in a research project at the Beuth Hochschule für Technik Berlin - and is being further developed for kinematic applications. The project is embedded in the European Social Fund. It is a follow-up project in the area of static positioning with single GNSS frequency receivers [KORTH and HOFMANN, 2011].

Improved treatment of global positioning system force parameters in precise orbit determination applications

NASA Technical Reports Server (NTRS)

Vigue, Y.; Lichten, S. M.; Muellerschoen, R. J.; Blewitt, G.; Heflin, M. B.

1993-01-01

Data collected from a worldwide 1992 experiment were processed at JPL to determine precise orbits for the satellites of the Global Positioning System (GPS). A filtering technique was tested to improve modeling of solar-radiation pressure force parameters for GPS satellites. The new approach improves orbit quality for eclipsing satellites by a factor of two, with typical results in the 25- to 50-cm range. The resultant GPS-based estimates for geocentric coordinates of the tracking sites, which include the three DSN sites, are accurate to 2 to 8 cm, roughly equivalent to 3 to 10 nrad of angular measure.

Application of Template Matching for Improving Classification of Urban Railroad Point Clouds

PubMed Central

Arastounia, Mostafa; Oude Elberink, Sander

2016-01-01

This study develops an integrated data-driven and model-driven approach (template matching) that clusters the urban railroad point clouds into three classes of rail track, contact cable, and catenary cable. The employed dataset covers 630 m of the Dutch urban railroad corridors in which there are four rail tracks, two contact cables, and two catenary cables. The dataset includes only geometrical information (three dimensional (3D) coordinates of the points) with no intensity data and no RGB data. The obtained results indicate that all objects of interest are successfully classified at the object level with no false positives and no false negatives. The results also show that an average 97.3% precision and an average 97.7% accuracy at the point cloud level are achieved. The high precision and high accuracy of the rail track classification (both greater than 96%) at the point cloud level stems from the great impact of the employed template matching method on excluding the false positives. The cables also achieve quite high average precision (96.8%) and accuracy (98.4%) due to their high sampling and isolated position in the railroad corridor. PMID:27973452

A new measurement method of actual focal spot position of an x-ray tube using a high-precision carbon-interspaced grid

NASA Astrophysics Data System (ADS)

Lee, H. W.; Lim, H. W.; Jeon, D. H.; Park, C. K.; Cho, H. S.; Seo, C. W.; Lee, D. Y.; Kim, K. S.; Kim, G. A.; Park, S. Y.; Kang, S. Y.; Park, J. E.; Kim, W. S.; Woo, T. H.; Oh, J. E.

2018-06-01

This study investigated the effectiveness of a new method for measuring the actual focal spot position of a diagnostic x-ray tube using a high-precision antiscatter grid and a digital x-ray detector in which grid magnification, which is directly related to the focal spot position, was determined from the Fourier spectrum of the acquired x-ray grid’s image. A systematic experiment was performed to demonstrate the viability of the proposed measurement method. The hardware system used in the experiment consisted of an x-ray tube run at 50 kVp and 1 mA, a flat-panel detector with a pixel size of 49.5 µm, and a high-precision carbon-interspaced grid with a strip density of 200 lines/inch. The results indicated that the focal spot of the x-ray tube (Jupiter 5000, Oxford Instruments) used in the experiment was located approximately 31.10 mm inside from the exit flange, well agreed with the nominal value of 31.05 mm, which demonstrates the viability of the proposed measurement method. Thus, the proposed method can be utilized for system’s performance optimization in many x-ray imaging applications.

The contribution of Multi-GNSS Experiment (MGEX) to precise point positioning

NASA Astrophysics Data System (ADS)

Guo, Fei; Li, Xingxing; Zhang, Xiaohong; Wang, Jinling

2017-06-01

In response to the changing world of GNSS, the International GNSS Service (IGS) has initiated the Multi-GNSS Experiment (MGEX). As part of the MGEX project, initial precise orbit and clock products have been released for public use, which are the key prerequisites for multi-GNSS precise point positioning (PPP). In particular, precise orbits and clocks at intervals of 5 min and 30 s are presently available for the new emerging systems. This paper investigates the benefits of multi-GNSS for PPP. Firstly, orbit and clock consistency tests (between different providers) were performed for GPS, GLONASS, Galileo and BeiDou. In general, the differences of GPS are, respectively, 1.0-1.5 cm for orbit and 0.1 ns for clock. The consistency of GLONASS is worse than GPS by a factor of 2-3, i.e. 2-4 cm for orbit and 0.2 ns for clock. However, the corresponding differences of Galileo and BeiDou are significantly larger than those of GPS and GLONASS, particularly for the BeiDou GEO satellites. Galileo as well as BeiDou IGSO/MEO products have a consistency of 0.1-0.2 m for orbit, and 0.2-0.3 ns for clock. As to BeiDou GEO satellites, the difference of their orbits reaches 3-4 m in along-track, 0.5-0.6 m in cross-track, and 0.2-0.3 m in the radial directions, together with an average RMS of 0.6 ns for clock. Furthermore, the short-term stability of multi-GNSS clocks was analyzed by Allan deviation. Results show that clock stability of the onboard GNSS is highly dependent on the satellites generations, operational lifetime, orbit types, and frequency standards. Finally, kinematic PPP tests were conducted to investigate the contribution of multi-GNSS and higher rate clock corrections. As expected, the positioning accuracy as well as convergence speed benefit from the fusion of multi-GNSS and higher rate of precise clock corrections. The multi-GNSS PPP improves the positioning accuracy by 10-20%, 40-60%, and 60-80% relative to the GPS-, GLONASS-, and BeiDou-only PPP. The usage of 30 s interval clock products decreases interpolation errors, and the positioning accuracy is improved by an average of 30-50% for the all the cases except for the BeiDou-only PPP.

Analysis of CAD Model-based Visual Tracking for Microassembly using a New Block Set for MATLAB/Simulink

NASA Astrophysics Data System (ADS)

Kudryavtsev, Andrey V.; Laurent, Guillaume J.; Clévy, Cédric; Tamadazte, Brahim; Lutz, Philippe

2015-10-01

Microassembly is an innovative alternative to the microfabrication process of MOEMS, which is quite complex. It usually implies the use of microrobots controlled by an operator. The reliability of this approach has been already confirmed for micro-optical technologies. However, the characterization of assemblies has shown that the operator is the main source of inaccuracies in the teleoperated microassembly. Therefore, there is great interest in automating the microassembly process. One of the constraints of automation in microscale is the lack of high precision sensors capable to provide the full information about the object position. Thus, the usage of visual-based feedback represents a very promising approach allowing to automate the microassembly process. The purpose of this article is to characterize the techniques of object position estimation based on the visual data, i.e., visual tracking techniques from the ViSP library. These algorithms enables a 3-D object pose using a single view of the scene and the CAD model of the object. The performance of three main types of model-based trackers is analyzed and quantified: edge-based, texture-based and hybrid tracker. The problems of visual tracking in microscale are discussed. The control of the micromanipulation station used in the framework of our project is performed using a new Simulink block set. Experimental results are shown and demonstrate the possibility to obtain the repeatability below 1 µm.

Marker-Based Multi-Sensor Fusion Indoor Localization System for Micro Air Vehicles.

PubMed

Xing, Boyang; Zhu, Quanmin; Pan, Feng; Feng, Xiaoxue

2018-05-25

A novel multi-sensor fusion indoor localization algorithm based on ArUco marker is designed in this paper. The proposed ArUco mapping algorithm can build and correct the map of markers online with Grubbs criterion and K-mean clustering, which avoids the map distortion due to lack of correction. Based on the conception of multi-sensor information fusion, the federated Kalman filter is utilized to synthesize the multi-source information from markers, optical flow, ultrasonic and the inertial sensor, which can obtain a continuous localization result and effectively reduce the position drift due to the long-term loss of markers in pure marker localization. The proposed algorithm can be easily implemented in a hardware of one Raspberry Pi Zero and two STM32 micro controllers produced by STMicroelectronics (Geneva, Switzerland). Thus, a small-size and low-cost marker-based localization system is presented. The experimental results show that the speed estimation result of the proposed system is better than Px4flow, and it has the centimeter accuracy of mapping and positioning. The presented system not only gives satisfying localization precision, but also has the potential to expand other sensors (such as visual odometry, ultra wideband (UWB) beacon and lidar) to further improve the localization performance. The proposed system can be reliably employed in Micro Aerial Vehicle (MAV) visual localization and robotics control.

Curvature in Arabidopsis inflorescence stems is limited to the region of amyloplast displacement

NASA Technical Reports Server (NTRS)

Weise, S. E.; Kuznetsov, O. A.; Hasenstein, K. H.; Kiss, J. Z.

2000-01-01

Gravitropic sensing in stems and stem-like organs is hypothesized to occur in the endodermis. However, since the endodermis runs the entire length of the stem, the precise site of gravisensing has been difficult to define. In this investigation of gravisensitivity in inflorescence stems of Arabidopsis, we positioned stems in a high gradient magnetic field (HGMF) on a rotating clinostat. Approximately 40% of the young, wild-type (WT) inflorescences, for all positions tested, curved toward the HGMF in the vicinity of the stem exposed to the field. In contrast, when the wedge was placed in the basal region of older inflorescence stems, no curvature was observed. As a control, the HGMF was applied to a starchless mutant, and 5% of the stems curved toward the field. Microscopy of the endodermis in the WT showed amyloplast displacement in the vicinity of the HGMF. Additional structural studies demonstrated that the basal region of WT stems experienced amyloplast displacement and, therefore, suggest this region is capable of gravity perception. However, increased lignification likely prevented curvature in the basal region. The lack of apical curvature after basal amyloplast displacement indicates that gravity perception in the base is not transmitted to the apex. Thus, these results provide evidence that the signal (and thus, response) resulting from perception in Arabidopsis inflorescence stems is spatially restricted.

Geographic variations of ecosystem service intensity in Fuzhou City, China.

PubMed

Hu, Xisheng; Hong, Wei; Qiu, Rongzu; Hong, Tao; Chen, Can; Wu, Chengzhen

2015-04-15

Ecosystem services are strongly influenced by the landscape configuration of natural and human systems. So they are heterogeneous across landscapes. However lack of the knowledge of spatial variations of ecosystem services constrains the effective management and conservation of ecosystems. We presented a spatially explicit and quantitative assessment of the geographic variations in ecosystem services for the Fuzhou City in 2009 using exploratory spatial data analysis (ESDA) and semivariance analysis. Results confirmed a significant and positive spatial autocorrelation, and revealed several hot-spots and cold-spots for the spatial distribution of ecosystem service intensity (ESI) in the study area. Also the trend surface analysis indicated that the level of ESI tended to be reduced gradually from north to south and from west to east, with a trough in the urban central area, which was quite in accordance with land-use structure. A more precise cluster map was then developed using the range of lag distance, deriving from semivariance analysis, as neighborhood size instead of default value in the software of ESRI ArcGIS 10.0, and geographical clusters where population growth and land-use pressure varied significantly and positively with ESI across the city were also created by geographically weighted regression (GWR). This study has good policy implications applicable to prioritize areas for conservation or construction, and design ecological corridor to improve ecosystem service delivery to benefiting areas. Copyright © 2015 Elsevier B.V. All rights reserved.

Altered center of mass control during sit-to-walk in elderly adults with and without history of falling.

PubMed

Chen, Tzurei; Chou, Li-Shan

2013-09-01

Sit-to-walk (STW) is a commonly performed activity of daily living that requires a precise coordination between momentum generation and balance control. However, there is a lack of biomechanical data demonstrating how the center of mass (COM) momentum and balance control interact. This study examines COM kinetic energy distribution in three movement directions and COM-Ankle inclination angles during STW among 15 healthy young adults, 15 elderly non-fallers, and 15 elderly fallers. We found that elderly adults, especially elderly fallers, chose a COM control strategy that provided more stability than mobility to perform STW. A smaller forward COM velocity, a more upward COM momentum distribution, and a smaller anterior-posterior COM-Ankle angle characterize this strategy. Healthy elderly adults modified their STW movement around seat-off so that they achieved a more upright position before walking. Elderly fallers not only altered COM control around seat-off but also showed limitation in COM control during gait initiation. Furthermore, their COM control in the medial-lateral direction might be perturbed at swing-off due to an increased distribution of kinetic energy. Examining COM momentum distribution in different movement directions and the relationship between positions of the COM and supporting foot during STW could enhance our ability to identify elderly adults who are at risk of falling. Copyright © 2013 Elsevier B.V. All rights reserved.

Cancer Model Development Centers

Cancer.gov

The Cancer Model Development Centers (CMDCs) are the NCI-funded contributors to the HCMI. They are tasked with producing next-generation cancer models from clinical samples. The cancer models will encompass tumor types that are rare, originate from patients from underrepresented populations, or lack precision therapy. These models will be annotated with clinical and genomic data and will become a community resource.

Evaluation of neural network modeling to predict non-water-stressed leaf temperature in wine grape for calculation of crop water stress index

USDA-ARS?s Scientific Manuscript database

Precision irrigation management in wine grape production is hindered by the lack of a reliable method to easily quantify and monitor vine water status. Mild to moderate water stress is desirable in wine grape for controlling vine vigor and optimizing fruit yield and quality. A crop water stress ind...

Cold water as a climate shield to preserve native trout through the 21st Century

Treesearch

Daniel J. Isaak; Michael K. Young; David Nagel; Dona Horan

2014-01-01

Native trout are culturally and ecologically important, but also likely to undergo widespread declines as the coldwater environments they require continue to shrink in association with global warming. Much can be done to preserve these fish but efficient planning and targeting of conservations resources has been hindered by a lack of broad-scale datasets and precise...

"Just Wait Then and See What He Does": A Speech Act Analysis of Healthcare Professionals' Interaction Coaching with Parents of Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

McKnight, Lindsay M.; O'Malley-Keighran, Mary-Pat; Carroll, Clare

2016-01-01

Background: There is evidence indicating that parent training programmes including interaction coaching of parents of children with autism spectrum disorders (ASD) can increase parental responsiveness, promote language development and social interaction skills in children with ASD. However, there is a lack of research exploring precisely how…

Coordinated crew performance in commercial aircraft operations

NASA Technical Reports Server (NTRS)

Murphy, M. R.

1977-01-01

A specific methodology is proposed for an improved system of coding and analyzing crew member interaction. The complexity and lack of precision of many crew and task variables suggest the usefulness of fuzzy linguistic techniques for modeling and computer simulation of the crew performance process. Other research methodologies and concepts that have promise for increasing the effectiveness of research on crew performance are identified.

Reliable positioning in a sparse GPS network, eastern Ontario

NASA Astrophysics Data System (ADS)

Samadi Alinia, H.; Tiampo, K.; Atkinson, G. M.

2013-12-01

Canada hosts two regions that are prone to large earthquakes: western British Columbia, and the St. Lawrence River region in eastern Canada. Although eastern Ontario is not as seismically active as other areas of eastern Canada, such as the Charlevoix/Ottawa Valley seismic zone, it experiences ongoing moderate seismicity. In historic times, potentially damaging events have occurred in New York State (Attica, 1929, M=5.7; Plattsburg, 2002, M=5.0), north-central Ontario (Temiskaming, 1935, M=6.2; North Bay, 2000, M=5.0), eastern Ontario (Cornwall, 1944, M=5.8), Georgian Bay (2005, MN=4.3), and western Quebec (Val-Des-Bois,2010, M=5.0, MN=5.8). In eastern Canada, the analysis of detailed, high-precision measurements of surface deformation is a key component in our efforts to better characterize the associated seismic hazard. The data from precise, continuous GPS stations is necessary to adequately characterize surface velocities from which patterns and rates of stress accumulation on faults can be estimated (Mazzotti and Adams, 2005; Mazzotti et al., 2005). Monitoring of these displacements requires employing high accuracy GPS positioning techniques. Detailed strain measurements can determine whether the regional strain everywhere is commensurate with a large event occurring every few hundred years anywhere within this general area or whether large earthquakes are limited to specific areas (Adams and Halchuck, 2003; Mazzotti and Adams, 2005). In many parts of southeastern Ontario and western Québec, GPS stations are distributed quite sparsely, with spacings of approximately 100 km or more. The challenge is to provide accurate solutions for these sparse networks with an approach that is capable of achieving high-accuracy positioning. Here, various reduction techniques are applied to a sparse network installed with the Southern Ontario Seismic Network in eastern Ontario. Recent developments include the implementation of precise point positioning processing on acquired GPS raw data. These are based on precise GPS orbit and clock data products with centimeter accuracy computed beforehand. Here, the analysis of 1Hz GPS data is conducted in order to find the most reliable regional network from eight stations (STCO, TYNO, ACTO, INUQ, IVKQ, KLBO, MATQ and ALGO) that cover the study area in eastern Ontario. In this way, the estimated parameters are the total number of ambiguities and resolved ambiguities, posteriori rms of each baseline and the coordinates for each station and their differences with the known coordinates. The positioning accuracy, the corrections and the accuracy of interpolated corrections, and the initialization time required for precise positioning are presented for the various applications.

Congenital Toxoplasmosis: A Plea for a Neglected Disease

PubMed Central

Wallon, Martine; Peyron, François

2018-01-01

Maternal infection by Toxoplasma gondii during pregnancy may have serious consequences for the fetus, ranging from miscarriage, central nervous system involvement, retinochoroiditis, or subclinical infection at birth with a risk of late onset of ocular diseases. As infection in pregnant women is usually symptomless, the diagnosis relies only on serological tests. Some countries like France and Austria have organized a regular serological testing of pregnant women, some others have no prenatal program of surveillance. Reasons for these discrepant attitudes are many and debatable. Among them are the efficacy of antenatal treatment and cost-effectiveness of such a program. A significant body of data demonstrated that rapid onset of treatment after maternal infection reduces the risk and severity of fetal infection. Recent cost-effectiveness studies support regular screening. This lack of consensus put both pregnant women and care providers in a difficult situation. Another reason why congenital toxoplasmosis is disregarded in some countries is the lack of precise information about its impact on the population. Precise estimations on the burden of the disease can be achieved by systematic screening that will avoid bias or underreporting of cases and provide a clear view of its outcome. PMID:29473896

Precision laser aiming system

DOEpatents

Ahrens, Brandon R [Albuquerque, NM; Todd, Steven N [Rio Rancho, NM

2009-04-28

A precision laser aiming system comprises a disrupter tool, a reflector, and a laser fixture. The disrupter tool, the reflector and the laser fixture are configurable for iterative alignment and aiming toward an explosive device threat. The invention enables a disrupter to be quickly and accurately set up, aligned, and aimed in order to render safe or to disrupt a target from a standoff position.

Application of high precision two-way S-band ranging to the navigation of the Galileo Earth encounters

NASA Technical Reports Server (NTRS)

Pollmeier, Vincent M.; Kallemeyn, Pieter H.; Thurman, Sam W.

1993-01-01

The application of high-accuracy S/S-band (2.1 GHz uplink/2.3 GHz downlink) ranging to orbit determination with relatively short data arcs is investigated for the approach phase of each of the Galileo spacecraft's two Earth encounters (8 December 1990 and 8 December 1992). Analysis of S-band ranging data from Galileo indicated that under favorable signal levels, meter-level precision was attainable. It is shown that ranginging data of sufficient accuracy, when acquired from multiple stations, can sense the geocentric angular position of a distant spacecraft. Explicit modeling of ranging bias parameters for each station pass is used to largely remove systematic ground system calibration errors and transmission media effects from the Galileo range measurements, which would otherwise corrupt the angle finding capabilities of the data. The accuracy achieved using the precision range filtering strategy proved markedly better when compared to post-flyby reconstructions than did solutions utilizing a traditional Doppler/range filter strategy. In addition, the navigation accuracy achieved with precision ranging was comparable to that obtained using delta-Differenced One-Way Range, an interferometric measurement of spacecraft angular position relative to a natural radio source, which was also used operationally.

Formation of bone-like mineralized matrix by periodontal ligament cells in vivo: a morphological study in rats.

PubMed

Hiraga, Toru; Ninomiya, Tadashi; Hosoya, Akihiro; Takahashi, Masafumi; Nakamura, Hiroaki

2009-01-01

Periodontal ligament (PDL) is a unique connective tissue that not only connects cementum and alveolar bone to support teeth, but also plays an important role in reconstructing periodontal tissues. Previous studies have suggested that PDL cells have osteogenic potential; however, they lack precise histological examinations. Here, we studied bone-like matrix formation by PDL cells in rats using morphological techniques. Rat and human PDL cells exhibited substantial alkaline phosphatase activity and induced mineralization in vitro. RT-PCR analyses showed that PDL cells expressed the osteoblast markers, Runx2, osterix, and osteocalcin. These results suggest that PDL cells share similar phenotypes with osteoblasts. To examine the bone-like matrix formation in vivo, PDL cells isolated from green fluorescent protein (GFP)-transgenic rats were inoculated with hydroxyapatite (HA) disks into wild-type rats. Five weeks after the implantation, the pores in HA disks were occupied by GFP-positive cells. Mineralized matrix formation was also found on the surface of HA pores. At 12 weeks, some of the pores were filled with bone-like mineralized matrices (BLMM), which were positive for the bone matrix proteins, osteopontin, bone sialoprotein, and osteocalcin. Immunohistochemical examination revealed that most of the osteoblast- and osteocyte-like cells on or in the BLMM were GFP-positive, suggesting that the BLMM were directly formed by the inoculated PDL cells. On the pore surfaces, Sharpey's fiber-like structures embedded in cementum-like mineralized layers were also observed. These results collectively suggest that PDL cells have the ability to form periodontal tissues and could be a useful source for regenerative therapies of periodontal diseases.

Technical note: a landmark-based approach to the study of the ear ossicles using ultra-high-resolution X-ray computed tomography data.

PubMed

Schmidt, Jodi L; Cole, Theodore M; Silcox, Mary T

2011-08-01

Previous study of the ear ossicles in Primates has demonstrated that they vary on both functional and phylogenetic bases. Such studies have generally employed two-dimensional linear measurements rather than three-dimensional data. The availability of Ultra- high-resolution X-ray computed tomography (UhrCT) has made it possible to accurately image the ossicles so that broadly accepted methodologies for acquiring and studying morphometric data can be applied. Using UhrCT data also allows for the ossicular chain to be studied in anatomical position, so that it is possible to consider the spatial and size relationships of all three bones. One issue impeding the morphometric study of the ear ossicles is a lack of broadly recognized landmarks. Distinguishing landmarks on the ossicles is difficult in part because there are only two areas of articulation in the ossicular chain, one of which (the malleus/incus articulation) has a complex three-dimensional form. A measurement error study is presented demonstrating that a suite of 16 landmarks can be precisely located on reconstructions of the ossicles from UhrCT data. Estimates of measurement error showed that most landmarks were highly replicable, with an average CV for associated interlandmark distances of less than 3%. The positions of these landmarks are chosen to reflect not only the overall shape of the bones in the chain and their relative positions, but also functional parameters. This study should provide a basis for further examination of the smallest bones in the body in three dimensions. Copyright © 2011 Wiley-Liss, Inc.

The Accuracy and Precision of Position and Orientation Tracking in the HTC Vive Virtual Reality System for Scientific Research

PubMed Central

Niehorster, Diederick C.; Li, Li; Lappe, Markus

2017-01-01

The advent of inexpensive consumer virtual reality equipment enables many more researchers to study perception with naturally moving observers. One such system, the HTC Vive, offers a large field-of-view, high-resolution head mounted display together with a room-scale tracking system for less than a thousand U.S. dollars. If the position and orientation tracking of this system is of sufficient accuracy and precision, it could be suitable for much research that is currently done with far more expensive systems. Here we present a quantitative test of the HTC Vive’s position and orientation tracking as well as its end-to-end system latency. We report that while the precision of the Vive’s tracking measurements is high and its system latency (22 ms) is low, its position and orientation measurements are provided in a coordinate system that is tilted with respect to the physical ground plane. Because large changes in offset were found whenever tracking was briefly lost, it cannot be corrected for with a one-time calibration procedure. We conclude that the varying offset between the virtual and the physical tracking space makes the HTC Vive at present unsuitable for scientific experiments that require accurate visual stimulation of self-motion through a virtual world. It may however be suited for other experiments that do not have this requirement. PMID:28567271

An innovative method for coordinate measuring machine one-dimensional self-calibration with simplified experimental process.

PubMed

Fang, Cheng; Butler, David Lee

2013-05-01

In this paper, an innovative method for CMM (Coordinate Measuring Machine) self-calibration is proposed. In contrast to conventional CMM calibration that relies heavily on a high precision reference standard such as a laser interferometer, the proposed calibration method is based on a low-cost artefact which is fabricated with commercially available precision ball bearings. By optimizing the mathematical model and rearranging the data sampling positions, the experimental process and data analysis can be simplified. In mathematical expression, the samples can be minimized by eliminating the redundant equations among those configured by the experimental data array. The section lengths of the artefact are measured at arranged positions, with which an equation set can be configured to determine the measurement errors at the corresponding positions. With the proposed method, the equation set is short of one equation, which can be supplemented by either measuring the total length of the artefact with a higher-precision CMM or calibrating the single point error at the extreme position with a laser interferometer. In this paper, the latter is selected. With spline interpolation, the error compensation curve can be determined. To verify the proposed method, a simple calibration system was set up on a commercial CMM. Experimental results showed that with the error compensation curve uncertainty of the measurement can be reduced to 50%.

Characteristics of the BDS Carrier Phase Multipath and Its Mitigation Methods in Relative Positioning

PubMed Central

Dai, Wujiao; Shi, Qiang; Cai, Changsheng

2017-01-01

The carrier phase multipath effect is one of the most significant error sources in the precise positioning of BeiDou Navigation Satellite System (BDS). We analyzed the characteristics of BDS multipath, and found the multipath errors of geostationary earth orbit (GEO) satellite signals are systematic, whereas those of inclined geosynchronous orbit (IGSO) or medium earth orbit (MEO) satellites are both systematic and random. The modified multipath mitigation methods, including sidereal filtering algorithm and multipath hemispherical map (MHM) model, were used to improve BDS dynamic deformation monitoring. The results indicate that the sidereal filtering methods can reduce the root mean square (RMS) of positioning errors in the east, north and vertical coordinate directions by 15%, 37%, 25% and 18%, 51%, 27% in the coordinate and observation domains, respectively. By contrast, the MHM method can reduce the RMS by 22%, 52% and 27% on average. In addition, the BDS multipath errors in static baseline solutions are a few centimeters in multipath-rich environments, which is different from that of Global Positioning System (GPS) multipath. Therefore, we add a parameter representing the GEO multipath error in observation equation to the adjustment model to improve the precision of BDS static baseline solutions. And the results show that the modified model can achieve an average precision improvement of 82%, 54% and 68% in the east, north and up coordinate directions, respectively. PMID:28387744

Characteristics of the BDS Carrier Phase Multipath and Its Mitigation Methods in Relative Positioning.

PubMed

Dai, Wujiao; Shi, Qiang; Cai, Changsheng

2017-04-07

The carrier phase multipath effect is one of the most significant error sources in the precise positioning of BeiDou Navigation Satellite System (BDS). We analyzed the characteristics of BDS multipath, and found the multipath errors of geostationary earth orbit (GEO) satellite signals are systematic, whereas those of inclined geosynchronous orbit (IGSO) or medium earth orbit (MEO) satellites are both systematic and random. The modified multipath mitigation methods, including sidereal filtering algorithm and multipath hemispherical map (MHM) model, were used to improve BDS dynamic deformation monitoring. The results indicate that the sidereal filtering methods can reduce the root mean square (RMS) of positioning errors in the east, north and vertical coordinate directions by 15%, 37%, 25% and 18%, 51%, 27% in the coordinate and observation domains, respectively. By contrast, the MHM method can reduce the RMS by 22%, 52% and 27% on average. In addition, the BDS multipath errors in static baseline solutions are a few centimeters in multipath-rich environments, which is different from that of Global Positioning System (GPS) multipath. Therefore, we add a parameter representing the GEO multipath error in observation equation to the adjustment model to improve the precision of BDS static baseline solutions. And the results show that the modified model can achieve an average precision improvement of 82%, 54% and 68% in the east, north and up coordinate directions, respectively.

The Accuracy and Precision of Position and Orientation Tracking in the HTC Vive Virtual Reality System for Scientific Research.

PubMed

Niehorster, Diederick C; Li, Li; Lappe, Markus

2017-01-01

The advent of inexpensive consumer virtual reality equipment enables many more researchers to study perception with naturally moving observers. One such system, the HTC Vive, offers a large field-of-view, high-resolution head mounted display together with a room-scale tracking system for less than a thousand U.S. dollars. If the position and orientation tracking of this system is of sufficient accuracy and precision, it could be suitable for much research that is currently done with far more expensive systems. Here we present a quantitative test of the HTC Vive's position and orientation tracking as well as its end-to-end system latency. We report that while the precision of the Vive's tracking measurements is high and its system latency (22 ms) is low, its position and orientation measurements are provided in a coordinate system that is tilted with respect to the physical ground plane. Because large changes in offset were found whenever tracking was briefly lost, it cannot be corrected for with a one-time calibration procedure. We conclude that the varying offset between the virtual and the physical tracking space makes the HTC Vive at present unsuitable for scientific experiments that require accurate visual stimulation of self-motion through a virtual world. It may however be suited for other experiments that do not have this requirement.

Development and Testing of a High-Precision Position and Attitude Measuring System for a Space Mechanism

NASA Technical Reports Server (NTRS)

Khanenya, Nikolay; Paciotti, Gabriel; Forzani, Eugenio; Blecha, Luc

2016-01-01

This paper describes a high-precision optical metrology system - a unique ground test equipment which was designed and implemented for simultaneous precise contactless measurements of 6 degrees-of-freedom (3 translational + 3 rotational) of a space mechanism end-effector [1] in a thermally controlled ISO 5 clean environment. The developed contactless method reconstructs both position and attitude of the specimen from three cross-sections measured by 2D distance sensors [2]. The cleanliness is preserved by the hermetic test chamber filled with high purity nitrogen. The specimen's temperature is controlled by the thermostat [7]. The developed method excludes errors caused by the thermal deformations and manufacturing inaccuracies of the test jig. Tests and simulations show that the measurement accuracy of an object absolute position is of 20 micron in in-plane measurement (XY) and about 50 micron out of plane (Z). The typical absolute attitude is determined with an accuracy better than 3 arcmin in rotation around X and Y and better than 10 arcmin in Z. The metrology system is able to determine relative position and movement with an accuracy one order of magnitude lower than the absolute accuracy. Typical relative displacement measurement accuracies are better than 1 micron in X and Y and about 2 micron in Z. Finally, the relative rotation can be measured with accuracy better than 20 arcsec in any direction.

Effective techniques for changing physical activity and healthy eating intentions and behaviour: A systematic review and meta-analysis.

PubMed

McDermott, Máirtín S; Oliver, Madalyn; Iverson, Don; Sharma, Rajeev

2016-11-01

The primary aim of this study was to review the evidence on the impact of a change in intention on behaviour and to identify (1) behaviour change techniques (BCTs) associated with changes in intention and (2) whether the same BCTs are also associated with changes in behaviour. A systematic review was conducted to identify interventions that produced a significant change in intention and assessed the impact of this change on behaviour at a subsequent time point. Each intervention was coded using a taxonomy of BCTs targeting healthy eating and physical activity. A series of meta-regression analyses were conducted to identify effective BCTs. In total, 25 reports were included. Interventions had a medium-to-large effect on intentions (d +  = 0.64) and a small-to-medium effect (d +  = 0.41) on behaviour. One BCT, 'provide information on the consequences of behaviour in general', was significantly associated with a positive change in intention. One BCT, 'relapse prevention/coping planning', was associated with a negative change in intention. No BCTs were found to have significant positive effects on behaviour. However, one BCT, 'provide feedback on performance', was found to have a significant negative effect. BCTs aligned with social cognitive theory were found to have significantly greater positive effects on intention (d +  = 0.83 vs. 0.56, p < .05), but not behaviour (d +  = 0.35 vs. 0.23, ns), than those aligned with the theory of planned behaviour. Although the included studies support the notion that a change in intention is associated with a change in behaviour, this review failed to produce evidence on how to facilitate behaviour change through a change in intention. Larger meta-analyses incorporating interventions targeting a broader range of behaviours may be warranted. Statement of contribution What is already known on this subject? Prior research on the causal relationship between intention and behaviour has produced mixed findings. Further experimental research to determine the precise nature of these variables is clearly warranted. However, precise guidance on how to change intention is still lacking. What does this study add? This study aimed to identify behaviour change techniques associated with changes in intention and behaviour. Techniques with positive effects on intention were identified; however, these did not have an impact on behaviour. Larger meta-analyses incorporating interventions targeting a broader range of behaviours may be warranted. © 2016 The British Psychological Society.

Determining Locations by Use of Networks of Passive Beacons

NASA Technical Reports Server (NTRS)

Okino, Clayton; Gray, Andrew; Jennings, Esther

2009-01-01

Networks of passive radio beacons spanning moderate-sized terrain areas have been proposed to aid navigation of small robotic aircraft that would be used to explore Saturn s moon Titan. Such networks could also be used on Earth to aid navigation of robotic aircraft, land vehicles, or vessels engaged in exploration or reconnaissance in situations or locations (e.g., underwater locations) in which Global Positioning System (GPS) signals are unreliable or unavailable. Prior to use, it would be necessary to pre-position the beacons at known locations that would be determined by use of one or more precise independent global navigation system(s). Thereafter, while navigating over the area spanned by a given network of passive beacons, an exploratory robot would use the beacons to determine its position precisely relative to the known beacon positions (see figure). If it were necessary for the robot to explore multiple, separated terrain areas spanned by different networks of beacons, the robot could use a long-haul, relatively coarse global navigation system for the lower-precision position determination needed during transit between such areas. The proposed method of precise determination of position of an exploratory robot relative to the positions of passive radio beacons is based partly on the principles of radar and partly on the principles of radio-frequency identification (RFID) tags. The robot would transmit radar-like signals that would be modified and reflected by the passive beacons. The distance to each beacon would be determined from the roundtrip propagation time and/or round-trip phase shift of the signal returning from that beacon. Signals returned from different beacons could be distinguished by means of their RFID characteristics. Alternatively or in addition, the antenna of each beacon could be designed to radiate in a unique pattern that could be identified by the navigation system. Also, alternatively or in addition, sets of identical beacons could be deployed in unique configurations such that the navigation system could identify their unique combinations of radio-frequency reflections as an alternative to leveraging the uniqueness of the RFID tags. The degree of dimensional accuracy would depend not only on the locations of the beacons but also on the number of beacon signals received, the number of samples of each signal, the motion of the robot, and the time intervals between samples. At one extreme, a single sample of the return signal from a single beacon could be used to determine the distance from that beacon and hence to determine that the robot is located somewhere on a sphere, the radius of which equals that distance and the center of which lies at the beacon. In a less extreme example, the three-dimensional position of the robot could be determined with fair precision from a single sample of the signal from each of three beacons. In intermediate cases, position estimates could be refined and/or position ambiguities could be resolved by use of supplementary readings of an altimeter and other instruments aboard the robot.

GNSS global real-time augmentation positioning: Real-time precise satellite clock estimation, prototype system construction and performance analysis

NASA Astrophysics Data System (ADS)

Chen, Liang; Zhao, Qile; Hu, Zhigang; Jiang, Xinyuan; Geng, Changjiang; Ge, Maorong; Shi, Chuang

2018-01-01

Lots of ambiguities in un-differenced (UD) model lead to lower calculation efficiency, which isn't appropriate for the high-frequency real-time GNSS clock estimation, like 1 Hz. Mixed differenced model fusing UD pseudo-range and epoch-differenced (ED) phase observations has been introduced into real-time clock estimation. In this contribution, we extend the mixed differenced model for realizing multi-GNSS real-time clock high-frequency updating and a rigorous comparison and analysis on same conditions are performed to achieve the best real-time clock estimation performance taking the efficiency, accuracy, consistency and reliability into consideration. Based on the multi-GNSS real-time data streams provided by multi-GNSS Experiment (MGEX) and Wuhan University, GPS + BeiDou + Galileo global real-time augmentation positioning prototype system is designed and constructed, including real-time precise orbit determination, real-time precise clock estimation, real-time Precise Point Positioning (RT-PPP) and real-time Standard Point Positioning (RT-SPP). The statistical analysis of the 6 h-predicted real-time orbits shows that the root mean square (RMS) in radial direction is about 1-5 cm for GPS, Beidou MEO and Galileo satellites and about 10 cm for Beidou GEO and IGSO satellites. Using the mixed differenced estimation model, the prototype system can realize high-efficient real-time satellite absolute clock estimation with no constant clock-bias and can be used for high-frequency augmentation message updating (such as 1 Hz). The real-time augmentation message signal-in-space ranging error (SISRE), a comprehensive accuracy of orbit and clock and effecting the users' actual positioning performance, is introduced to evaluate and analyze the performance of GPS + BeiDou + Galileo global real-time augmentation positioning system. The statistical analysis of real-time augmentation message SISRE is about 4-7 cm for GPS, whlile 10 cm for Beidou IGSO/MEO, Galileo and about 30 cm for BeiDou GEO satellites. The real-time positioning results prove that the GPS + BeiDou + Galileo RT-PPP comparing to GPS-only can effectively accelerate convergence time by about 60%, improve the positioning accuracy by about 30% and obtain averaged RMS 4 cm in horizontal and 6 cm in vertical; additionally RT-SPP accuracy in the prototype system can realize positioning accuracy with about averaged RMS 1 m in horizontal and 1.5-2 m in vertical, which are improved by 60% and 70% to SPP based on broadcast ephemeris, respectively.

Validation of a new method for finding the rotational axes of the knee using both marker-based roentgen stereophotogrammetric analysis and 3D video-based motion analysis for kinematic measurements.

PubMed

Roland, Michelle; Hull, M L; Howell, S M

2011-05-01

In a previous paper, we reported the virtual axis finder, which is a new method for finding the rotational axes of the knee. The virtual axis finder was validated through simulations that were subject to limitations. Hence, the objective of the present study was to perform a mechanical validation with two measurement modalities: 3D video-based motion analysis and marker-based roentgen stereophotogrammetric analysis (RSA). A two rotational axis mechanism was developed, which simulated internal-external (or longitudinal) and flexion-extension (FE) rotations. The actual axes of rotation were known with respect to motion analysis and RSA markers within ± 0.0006 deg and ± 0.036 mm and ± 0.0001 deg and ± 0.016 mm, respectively. The orientation and position root mean squared errors for identifying the longitudinal rotation (LR) and FE axes with video-based motion analysis (0.26 deg, 0.28 m, 0.36 deg, and 0.25 mm, respectively) were smaller than with RSA (1.04 deg, 0.84 mm, 0.82 deg, and 0.32 mm, respectively). The random error or precision in the orientation and position was significantly better (p=0.01 and p=0.02, respectively) in identifying the LR axis with video-based motion analysis (0.23 deg and 0.24 mm) than with RSA (0.95 deg and 0.76 mm). There was no significant difference in the bias errors between measurement modalities. In comparing the mechanical validations to virtual validations, the virtual validations produced comparable errors to those of the mechanical validation. The only significant difference between the errors of the mechanical and virtual validations was the precision in the position of the LR axis while simulating video-based motion analysis (0.24 mm and 0.78 mm, p=0.019). These results indicate that video-based motion analysis with the equipment used in this study is the superior measurement modality for use with the virtual axis finder but both measurement modalities produce satisfactory results. The lack of significant differences between validation techniques suggests that the virtual sensitivity analysis previously performed was appropriately modeled. Thus, the virtual axis finder can be applied with a thorough understanding of its errors in a variety of test conditions.

Measuring the bias, precision, accuracy, and validity of self-reported height and weight in assessing overweight and obesity status among adolescents using a surveillance system.

PubMed

Pérez, Adriana; Gabriel, Kelley; Nehme, Eileen K; Mandell, Dorothy J; Hoelscher, Deanna M

2015-07-27

Evidence regarding bias, precision, and accuracy in adolescent self-reported height and weight across demographic subpopulations is lacking. The bias, precision, and accuracy of adolescent self-reported height and weight across subpopulations were examined using a large, diverse and representative sample of adolescents. A second objective was to develop correction equations for self-reported height and weight to provide more accurate estimates of body mass index (BMI) and weight status. A total of 24,221 students from 8th and 11th grade in Texas participated in the School Physical Activity and Nutrition (SPAN) surveillance system in years 2000-2002 and 2004-2005. To assess bias, the differences between the self-reported and objective measures, for height and weight were estimated. To assess precision and accuracy, the Lin's concordance correlation coefficient was used. BMI was estimated for self-reported and objective measures. The prevalence of students' weight status was estimated using self-reported and objective measures; absolute (bias) and relative error (relative bias) were assessed subsequently. Correction equations for sex and race/ethnicity subpopulations were developed to estimate objective measures of height, weight and BMI from self-reported measures using weighted linear regression. Sensitivity, specificity and positive predictive values of weight status classification using self-reported measures and correction equations are assessed by sex and grade. Students in 8th- and 11th-grade overestimated their height from 0.68cm (White girls) to 2.02 cm (African-American boys), and underestimated their weight from 0.4 kg (Hispanic girls) to 0.98 kg (African-American girls). The differences in self-reported versus objectively-measured height and weight resulted in underestimation of BMI ranging from -0.23 kg/m2 (White boys) to -0.7 kg/m2 (African-American girls). The sensitivity of self-reported measures to classify weight status as obese was 70.8% and 81.9% for 8th- and 11th-graders, respectively. These estimates increased when using the correction equations to 77.4% and 84.4% for 8th- and 11th-graders, respectively. When direct measurement is not practical, self-reported measurements provide a reliable proxy measure across grade, sex and race/ethnicity subpopulations of adolescents. Correction equations increase the sensitivity of self-report measures to identify prevalence of overall overweight/obesity status.

How precise can atoms of a nanocluster be located in 3D using a tilt series of scanning transmission electron microscopy images?

PubMed

Alania, M; De Backer, A; Lobato, I; Krause, F F; Van Dyck, D; Rosenauer, A; Van Aert, S

2017-10-01

In this paper, we investigate how precise atoms of a small nanocluster can ultimately be located in three dimensions (3D) from a tilt series of images acquired using annular dark field (ADF) scanning transmission electron microscopy (STEM). Therefore, we derive an expression for the statistical precision with which the 3D atomic position coordinates can be estimated in a quantitative analysis. Evaluating this statistical precision as a function of the microscope settings also allows us to derive the optimal experimental design. In this manner, the optimal angular tilt range, required electron dose, optimal detector angles, and number of projection images can be determined. Copyright © 2016 Elsevier B.V. All rights reserved.

GPS-based tracking system for TOPEX orbit determination

NASA Technical Reports Server (NTRS)

Melbourne, W. G.

1984-01-01

A tracking system concept is discussed that is based on the utilization of the constellation of Navstar satellites in the Global Positioning System (GPS). The concept involves simultaneous and continuous metric tracking of the signals from all visible Navstar satellites by approximately six globally distributed ground terminals and by the TOPEX spacecraft at 1300-km altitude. Error studies indicate that this system could be capable of obtaining decimeter position accuracies and, most importantly, around 5 cm in the radial component which is key to exploiting the full accuracy potential of the altimetric measurements for ocean topography. Topics covered include: background of the GPS, the precision mode for utilization of the system, past JPL research for using the GPS in precision applications, the present tracking system concept for high accuracy satellite positioning, and results from a proof-of-concept demonstration.

Mapping Nanoscale Hotspots with Single-Molecule Emitters Assembled into Plasmonic Nanocavities Using DNA Origami.

PubMed

Chikkaraddy, Rohit; Turek, V A; Kongsuwan, Nuttawut; Benz, Felix; Carnegie, Cloudy; van de Goor, Tim; de Nijs, Bart; Demetriadou, Angela; Hess, Ortwin; Keyser, Ulrich F; Baumberg, Jeremy J

2018-01-10

Fabricating nanocavities in which optically active single quantum emitters are precisely positioned is crucial for building nanophotonic devices. Here we show that self-assembly based on robust DNA-origami constructs can precisely position single molecules laterally within sub-5 nm gaps between plasmonic substrates that support intense optical confinement. By placing single-molecules at the center of a nanocavity, we show modification of the plasmon cavity resonance before and after bleaching the chromophore and obtain enhancements of ≥4 × 10 3 with high quantum yield (≥50%). By varying the lateral position of the molecule in the gap, we directly map the spatial profile of the local density of optical states with a resolution of ±1.5 nm. Our approach introduces a straightforward noninvasive way to measure and quantify confined optical modes on the nanoscale.

Properties of Ni^+ from microwave spectroscopy of n=9 Rydberg levels of Nickel

NASA Astrophysics Data System (ADS)

Woods, Shannon; Keele, Julie; Smith, Chris; Lundeen, Stephen

2012-06-01

The microwave/RESIS method was used to determine the relative positions of 15 of the n=9 Rydberg levels of Nickel with L >= 6. Because the ground state of the Ni^+ ion is a ^2D5/2 level, each Rydberg level (n,L) splits into six eigenstates whose relative positions are determined by long-range e-Ni^+ interactions present in addition to the dominant Coulomb interaction. A previous study with the optical RESIS method determined these positions with precision of +/- 30 MHz [1]. Using the microwave/RESIS method improves that precision by a factor of 300, and leads to much improved determinations of the Ni+ properties that control the long-range interactions. [4pt] [1] Julie A. Keele, Shannon L. Woods, M.E. Hanni, and S.R. Lundeen Phys. Rev. 81, 022506 (2010)

System for precise position registration

DOEpatents

Sundelin, Ronald M.; Wang, Tong

2005-11-22

An apparatus for enabling accurate retaining of a precise position, such as for reacquisition of a microscopic spot or feature having a size of 0.1 mm or less, on broad-area surfaces after non-in situ processing. The apparatus includes a sample and sample holder. The sample holder includes a base and three support posts. Two of the support posts interact with a cylindrical hole and a U-groove in the sample to establish location of one point on the sample and a line through the sample. Simultaneous contact of the third support post with the surface of the sample defines a plane through the sample. All points of the sample are therefore uniquely defined by the sample and sample holder. The position registration system of the current invention provides accuracy, as measured in x, y repeatability, of at least 140 .mu.m.

Precise Maps of RNA Polymerase Reveal How Promoters Direct Initiation and Pausing

PubMed Central

Kwak, Hojoong; Fuda, Nicholas J.; Core, Leighton J.; Lis, John T.

2014-01-01

Transcription regulation occurs frequently through promoter-associated pausing of RNA polymerase II (Pol II). We developed a Precision nuclear Run-On and sequencing assay (PRO-seq) to map the genome-wide distribution of transcriptionally-engaged Pol II at base-pair resolution. Pol II accumulates immediately downstream of promoters, at intron-exon junctions that are efficiently used for splicing, and over 3' poly-adenylation sites. Focused analyses of promoters reveal that pausing is not fixed relative to initiation sites nor is it specified directly by the position of a particular core promoter element or the first nucleosome. Core promoter elements function beyond initiation, and when optimally positioned they act collectively to dictate the position and strength of pausing. We test this ‘Complex Interaction’ model with insertional mutagenesis of the Drosophila Hsp70 core promoter. PMID:23430654

LDPC decoder with a limited-precision FPGA-based floating-point multiplication coprocessor

NASA Astrophysics Data System (ADS)

Moberly, Raymond; O'Sullivan, Michael; Waheed, Khurram

2007-09-01

Implementing the sum-product algorithm, in an FPGA with an embedded processor, invites us to consider a tradeoff between computational precision and computational speed. The algorithm, known outside of the signal processing community as Pearl's belief propagation, is used for iterative soft-decision decoding of LDPC codes. We determined the feasibility of a coprocessor that will perform product computations. Our FPGA-based coprocessor (design) performs computer algebra with significantly less precision than the standard (e.g. integer, floating-point) operations of general purpose processors. Using synthesis, targeting a 3,168 LUT Xilinx FPGA, we show that key components of a decoder are feasible and that the full single-precision decoder could be constructed using a larger part. Soft-decision decoding by the iterative belief propagation algorithm is impacted both positively and negatively by a reduction in the precision of the computation. Reducing precision reduces the coding gain, but the limited-precision computation can operate faster. A proposed solution offers custom logic to perform computations with less precision, yet uses the floating-point format to interface with the software. Simulation results show the achievable coding gain. Synthesis results help theorize the the full capacity and performance of an FPGA-based coprocessor.

Proposal for the creation of a national strategy for precision medicine in cancer: a position statement of SEOM, SEAP, and SEFH.

PubMed

Garrido, P; Aldaz, A; Vera, R; Calleja, M A; de Álava, E; Martín, M; Matías-Guiu, X; Palacios, J

2018-04-01

Precision medicine is an emerging approach for disease treatment and prevention that takes into account individual variability in genes, environment, and lifestyle for each person. Precision medicine is transforming clinical and biomedical research, as well as health care itself from a conceptual, as well as a methodological viewpoint, providing extraordinary opportunities to improve public health and lower the costs of the healthcare system. However, the implementation of precision medicine poses ethical-legal, regulatory, organizational, and knowledge-related challenges. Without a national strategy, precision medicine, which will be implemented one way or another, could take place without the appropriate planning that can guarantee technical quality, equal access of all citizens to the best practices, violating the rights of patients and professionals, and jeopardizing the solvency of the healthcare system. With this paper from the Spanish Societies of Medical Oncology, Pathology, and Hospital Pharmacy, we highlight the need to institute a consensual national strategy for the development of precision medicine in our country, review the national and international context, comment on the opportunities and challenges for implementing precision medicine, and outline the objectives of a national strategy on precision medicine in cancer.

An in-house assay for BK polyomavirus quantification using the Abbott m2000 RealTime system.

PubMed

Muldrew, Kenneth L; Lovett, Jennie L

2013-11-01

BK polyomavirus (BKPyV) quantification is useful for monitoring renal transplant patient response to therapy. The Abbott m2000 RealTime System employed by some clinical laboratories to perform US Food and Drug Administration-approved assays can also be used to develop in-house assays such as the one presented here. This study aimed to validate an in-house quantitative real-time PCR assay targeting the BKPyV major capsid VP1 gene for assessment of viral load using the Abbott m2000 RealTime System. BKPyV load was measured in 95 urine and plasma samples previously tested for BKPyV by one of three laboratories (46 BKPyV-positive samples consisting of 35 plasma and 11 urine samples; 49 samples negative for BKPyV consisting of 47 plasma and two urine samples). Two additional plasma specimens from the College of American Pathologists proficiency testing survey were also analysed. Precision studies were performed by diluting a high-viral-titre patient sample into BKPyV-negative pooled plasma to create high-positive (6.16 log10 copies ml(-1)) and low-positive (3.16 log10 copies ml(-1)) samples. For precision studies of inter-assay variability, a high-positive (7.0 log10 copies ml(-1)) and a low-positive (3.0 log10 copies ml(-1)) sample were measured in 20 separate runs. The assay's limit of quantification and limit of detection were 2.70 and 2.25 log10 copies ml(-1), respectively. The assay was linear from 2.70 to 9.26 log10 copies ml(-1). Of the 48 known positives, 43 were detected as positive, with three reported by the reference laboratory as values lower than the limit of detection. Two known positives at 3.27 and 3.80 log10 copies ml(-1) tested negative by the m2000 BKPyV assay. Of the 49 known negative samples, 48 were negative by the m2000 BKPyV load assay, with one sample confirmed positive by a reference laboratory. Qualitative analysis prior to discrepancy testing demonstrated a sensitivity of 89.58 % and a specificity of 97.96 %. Precision studies demonstrated inter-assay coefficients of variation of 0.63 % (high positive) and 4.38 % (low positive). Genotyping was performed on 22 patient samples, of which 21 (95.45 %) were type I and one (4.55 %) was type II. In conclusion, the m2000 BKPyV viral load assay sensitivity, specificity, linear range, precision and cost effectiveness make it an attractive methodology for clinical laboratories using the Abbott m2000 RealTime System.

HiCTMap: Detection and analysis of chromosome territory structure and position by high-throughput imaging.

PubMed

Jowhar, Ziad; Gudla, Prabhakar R; Shachar, Sigal; Wangsa, Darawalee; Russ, Jill L; Pegoraro, Gianluca; Ried, Thomas; Raznahan, Armin; Misteli, Tom

2018-06-01

The spatial organization of chromosomes in the nuclear space is an extensively studied field that relies on measurements of structural features and 3D positions of chromosomes with high precision and robustness. However, no tools are currently available to image and analyze chromosome territories in a high-throughput format. Here, we have developed High-throughput Chromosome Territory Mapping (HiCTMap), a method for the robust and rapid analysis of 2D and 3D chromosome territory positioning in mammalian cells. HiCTMap is a high-throughput imaging-based chromosome detection method which enables routine analysis of chromosome structure and nuclear position. Using an optimized FISH staining protocol in a 384-well plate format in conjunction with a bespoke automated image analysis workflow, HiCTMap faithfully detects chromosome territories and their position in 2D and 3D in a large population of cells per experimental condition. We apply this novel technique to visualize chromosomes 18, X, and Y in male and female primary human skin fibroblasts, and show accurate detection of the correct number of chromosomes in the respective genotypes. Given the ability to visualize and quantitatively analyze large numbers of nuclei, we use HiCTMap to measure chromosome territory area and volume with high precision and determine the radial position of chromosome territories using either centroid or equidistant-shell analysis. The HiCTMap protocol is also compatible with RNA FISH as demonstrated by simultaneous labeling of X chromosomes and Xist RNA in female cells. We suggest HiCTMap will be a useful tool for routine precision mapping of chromosome territories in a wide range of cell types and tissues. Published by Elsevier Inc.

An investigation into the performance of real-time GPS+GLONASS Precise Point Positioning (PPP) in New Zealand

NASA Astrophysics Data System (ADS)

Harima, Ken; Choy, Suelynn; Rizos, Chris; Kogure, Satoshi

2017-09-01

This paper presents an investigation into the performance of real-time Global Navigation Satellite Systems (GNSS) Precise Point Positioning (PPP) in New Zealand. The motivation of the research is to evaluate the feasibility of using PPP technique and a satellite based augmentation system such as the Japanese Quasi-Zenith Satellite System (QZSS) to deliver a real-time precise positioning solution in support of a nation-wide high accuracy GNSS positioning coverage in New Zealand. Two IGS real-time correction streams are evaluated alongside with the PPP correction messages transmitted by the QZSS satellite known as MDC1. MDC1 corrections stream is generated by Japan Aerospace Exploration Agency (JAXA) using the Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis (MADOCA) software and are currently transmitted in test mode by the QZSS satellite. The IGS real-time streams are the CLK9B real-time corrections stream generated by the French Centre National D'études Spatiales (CNES) using the PPP-Wizard software, and the CLK81 real-time corrections stream produced by GMV using their MagicGNSS software. GNSS data is collected from six New Zealand CORS stations operated by Land Information New Zealand (LINZ) over a one-week period in 2015. GPS and GLONASS measurements are processed in a real-time PPP mode using the satellite orbit and clock corrections from the real-time streams. The results show that positioning accuracies of 6 cm in horizontal component and 15 cm in vertical component can be achieved in real-time PPP. The real-time GPS+GLONASS PPP solution required 30 minutes to converge to within 10 cm horizontal positioning accuracy.

Precise correlation of histopathological and fluorescein angiographic morphology using retinal vascular casting.

PubMed

Bek, T; Prause, J U

1996-12-01

The histopathology of three eyes obtained post mortem from 2 patients with age-related macular degeneration was correlated with the pre mortem fluorescein angiographic morphology. A precise point-by-point correlation between histopathology and the corresponding angiographic appearance was ensured by using the cast retinal vascular system as a pattern of reference. The study showed that both the photoreceptors, the pigment epithelium, and substances accumulated between the retinal and the choroidal vascular systems, may have a blocking effect on choroidal background fluorescence as seen on fluorescein angiograms. Furthermore, it is confirmed that fluorescein angiographic hyperfluorescence may be due to a lack of blocking of the choroidal fluorescence because of a window defect in the retinal photoreceptor layer and/or the pigment epithelium.

Optical Excitation of Carbon Nanotubes Drives Localized Diazonium Reactions

PubMed Central

2016-01-01

Covalent chemistries have been widely used to modify carbon nanomaterials; however, they typically lack the precision and efficiency required to directly engineer their optical and electronic properties. Here, we show, for the first time, that visible light which is tuned into resonance with carbon nanotubes can be used to drive their functionalization by aryldiazonium salts. The optical excitation accelerates the reaction rate 154-fold (±13) and makes it possible to significantly improve the efficiency of covalent bonding to the sp2 carbon lattice. Control experiments suggest that the reaction is dominated by a localized photothermal effect. This light-driven reaction paves the way for precise nanochemistry that can directly tailor carbon nanomaterials at the optical and electronic levels. PMID:27588432

Lack of centrioles and primary cilia in STIL−/− mouse embryos

PubMed Central

David, Ahuvit; Liu, Fengying; Tibelius, Alexandra; Vulprecht, Julia; Wald, Diana; Rothermel, Ulrike; Ohana, Reut; Seitel, Alexander; Metzger, Jasmin; Ashery-Padan, Ruth; Meinzer, Hans-Peter; Gröne, Hermann-Josef; Izraeli, Shai; Krämer, Alwin

2014-01-01

Although most animal cells contain centrosomes, consisting of a pair of centrioles, their precise contribution to cell division and embryonic development is unclear. Genetic ablation of STIL, an essential component of the centriole replication machinery in mammalian cells, causes embryonic lethality in mice around mid gestation associated with defective Hedgehog signaling. Here, we describe, by focused ion beam scanning electron microscopy, that STIL−/− mouse embryos do not contain centrioles or primary cilia, suggesting that these organelles are not essential for mammalian development until mid gestation. We further show that the lack of primary cilia explains the absence of Hedgehog signaling in STIL−/− cells. Exogenous re-expression of STIL or STIL microcephaly mutants compatible with human survival, induced non-templated, de novo generation of centrioles in STIL−/− cells. Thus, while the abscence of centrioles is compatible with mammalian gastrulation, lack of centrioles and primary cilia impairs Hedgehog signaling and further embryonic development. PMID:25486474

Lack of centrioles and primary cilia in STIL(-/-) mouse embryos.

PubMed

David, Ahuvit; Liu, Fengying; Tibelius, Alexandra; Vulprecht, Julia; Wald, Diana; Rothermel, Ulrike; Ohana, Reut; Seitel, Alexander; Metzger, Jasmin; Ashery-Padan, Ruth; Meinzer, Hans-Peter; Gröne, Hermann-Josef; Izraeli, Shai; Krämer, Alwin

2014-01-01

Although most animal cells contain centrosomes, consisting of a pair of centrioles, their precise contribution to cell division and embryonic development is unclear. Genetic ablation of STIL, an essential component of the centriole replication machinery in mammalian cells, causes embryonic lethality in mice around mid gestation associated with defective Hedgehog signaling. Here, we describe, by focused ion beam scanning electron microscopy, that STIL(-/-) mouse embryos do not contain centrioles or primary cilia, suggesting that these organelles are not essential for mammalian development until mid gestation. We further show that the lack of primary cilia explains the absence of Hedgehog signaling in STIL(-/-) cells. Exogenous re-expression of STIL or STIL microcephaly mutants compatible with human survival, induced non-templated, de novo generation of centrioles in STIL(-/-) cells. Thus, while the abscence of centrioles is compatible with mammalian gastrulation, lack of centrioles and primary cilia impairs Hedgehog signaling and further embryonic development.

In praise of vagueness: malleability of vague information as a performance booster.

PubMed

Mishra, Himanshu; Mishra, Arul; Shiv, Baba

2011-06-01

Is the eternal quest for precise information always worthwhile? Our research suggests that, at times, vagueness has its merits. Previous research has demonstrated that people prefer precise information over vague information because it gives them a sense of security and makes their environments more predictable. However, we show that the fuzzy boundaries afforded by vague information can actually help individuals perform better than can precise information. We document these findings across two laboratory studies and one quasi-field study that involved different performance-related contexts (mental acuity, physical strength, and weight loss). We argue that the malleability of vague information allows people to interpret it in the manner they desire, so that they can generate positive response expectancies and, thereby, perform better. The rigidity of precise information discourages desirable interpretations. Hence, on certain occasions, precise information is not as helpful as vague information in boosting performance.

Validating precision estimates in horizontal wind measurements from a Doppler lidar

DOE PAGES

Newsom, Rob K.; Brewer, W. Alan; Wilczak, James M.; ...

2017-03-30

Results from a recent field campaign are used to assess the accuracy of wind speed and direction precision estimates produced by a Doppler lidar wind retrieval algorithm. The algorithm, which is based on the traditional velocity-azimuth-display (VAD) technique, estimates the wind speed and direction measurement precision using standard error propagation techniques, assuming the input data (i.e., radial velocities) to be contaminated by random, zero-mean, errors. For this study, the lidar was configured to execute an 8-beam plan-position-indicator (PPI) scan once every 12 min during the 6-week deployment period. Several wind retrieval trials were conducted using different schemes for estimating themore » precision in the radial velocity measurements. Here, the resulting wind speed and direction precision estimates were compared to differences in wind speed and direction between the VAD algorithm and sonic anemometer measurements taken on a nearby 300 m tower.« less

An Improved Method of AGM for High Precision Geolocation of SAR Images

NASA Astrophysics Data System (ADS)

Zhou, G.; He, C.; Yue, T.; Huang, W.; Huang, Y.; Li, X.; Chen, Y.

2018-05-01

In order to take full advantage of SAR images, it is necessary to obtain the high precision location of the image. During the geometric correction process of images, to ensure the accuracy of image geometric correction and extract the effective mapping information from the images, precise image geolocation is important. This paper presents an improved analytical geolocation method (IAGM) that determine the high precision geolocation of each pixel in a digital SAR image. This method is based on analytical geolocation method (AGM) proposed by X. K. Yuan aiming at realizing the solution of RD model. Tests will be conducted using RADARSAT-2 SAR image. Comparing the predicted feature geolocation with the position as determined by high precision orthophoto, results indicate an accuracy of 50m is attainable with this method. Error sources will be analyzed and some recommendations about improving image location accuracy in future spaceborne SAR's will be given.

Using laser technological unit ALTI "Karavella" for precision components of IEP production

NASA Astrophysics Data System (ADS)

Labin, N. A.; Chursin, A. D.; Paramonov, V. S.; Klimenko, V. I.; Paramonova, G. M.; Kolokolov, I. S.; Vinogradov, K. Y.; Betina, L. L.; Bulychev, N. A.; Dyakov, Yu. A.; Zakharyan, R. A.; Kazaryan, M. A.; Koshelev, K. K.; Kosheleva, O. K.; Grigoryants, A. G.; Shiganov, I. N.; Krasovskii, V. I.; Sachkov, V. I.; Plyaka, P. S.; Feofanov, I. N.; Chen, C.

2015-12-01

The paper revealed the using of industrial production equipment ALTI "Karavella-1", "Karavella-1M", "Karavella-2" and "Karavella-2M" precision components of IEP production [1-4]. The basis for the ALTI using in the IEP have become the positive results of research and development of technologies of foil (0.01-0.2 mm) and thin sheets (0.3-1 mm) materials micromachining by pulsed radiation CVL [5, 6]. To assess the micromachining quality and precision the measuring optical microscope (UHL VMM200), projection microscope (Mitutoyo PV5100) and Carl Zeiss microscope were used.

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

NASA Technical Reports Server (NTRS)

Sydnor, Richard L. (Editor)

1994-01-01

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