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1

Development of a GCR Event-based Risk Model  

NASA Technical Reports Server (NTRS)

A goal at NASA is to develop event-based systems biology models of space radiation risks that will replace the current dose-based empirical models. Complex and varied biochemical signaling processes transmit the initial DNA and oxidative damage from space radiation into cellular and tissue responses. Mis-repaired damage or aberrant signals can lead to genomic instability, persistent oxidative stress or inflammation, which are causative of cancer and CNS risks. Protective signaling through adaptive responses or cell repopulation is also possible. We are developing a computational simulation approach to galactic cosmic ray (GCR) effects that is based on biological events rather than average quantities such as dose, fluence, or dose equivalent. The goal of the GCR Event-based Risk Model (GERMcode) is to provide a simulation tool to describe and integrate physical and biological events into stochastic models of space radiation risks. We used the quantum multiple scattering model of heavy ion fragmentation (QMSFRG) and well known energy loss processes to develop a stochastic Monte-Carlo based model of GCR transport in spacecraft shielding and tissue. We validated the accuracy of the model by comparing to physical data from the NASA Space Radiation Laboratory (NSRL). Our simulation approach allows us to time-tag each GCR proton or heavy ion interaction in tissue including correlated secondary ions often of high multiplicity. Conventional space radiation risk assessment employs average quantities, and assumes linearity and additivity of responses over the complete range of GCR charge and energies. To investigate possible deviations from these assumptions, we studied several biological response pathway models of varying induction and relaxation times including the ATM, TGF -Smad, and WNT signaling pathways. We then considered small volumes of interacting cells and the time-dependent biophysical events that the GCR would produce within these tissue volumes to estimate how GCR event rates mapped to biological signaling induction and relaxation times. We considered several hypotheses related to signaling and cancer risk, and then performed simulations for conditions where aberrant or adaptive signaling would occur on long-duration space mission. Our results do not support the conventional assumptions of dose, linearity and additivity. A discussion on how event-based systems biology models, which focus on biological signaling as the mechanism to propagate damage or adaptation, can be further developed for cancer and CNS space radiation risk projections is given.

Cucinotta, Francis A.; Ponomarev, Artem L.; Plante, Ianik; Carra, Claudio; Kim, Myung-Hee

2009-01-01

2

GCR Environmental Models I: Sensitivity Analysis for GCR Environments  

NASA Technical Reports Server (NTRS)

Accurate galactic cosmic ray (GCR) models are required to assess crew exposure during long-duration missions to the Moon or Mars. Many of these models have been developed and compared to available measurements, with uncertainty estimates usually stated to be less than 15%. However, when the models are evaluated over a common epoch and propagated through to effective dose, relative differences exceeding 50% are observed. This indicates that the metrics used to communicate GCR model uncertainty can be better tied to exposure quantities of interest for shielding applications. This is the first of three papers focused on addressing this need. In this work, the focus is on quantifying the extent to which each GCR ion and energy group, prior to entering any shielding material or body tissue, contributes to effective dose behind shielding. Results can be used to more accurately calibrate model-free parameters and provide a mechanism for refocusing validation efforts on measurements taken over important energy regions. Results can also be used as references to guide future nuclear cross-section measurements and radiobiology experiments. It is found that GCR with Z>2 and boundary energies below 500 MeV/n induce less than 5% of the total effective dose behind shielding. This finding is important given that most of the GCR models are developed and validated against Advanced Composition Explorer/Cosmic Ray Isotope Spectrometer (ACE/CRIS) measurements taken below 500 MeV/n. It is therefore possible for two models to very accurately reproduce the ACE/CRIS data while inducing very different effective dose values behind shielding.

Slaba, Tony C.; Blattnig, Steve R.

2014-01-01

3

Nuclear interactions in heavy ion transport and event-based risk models.  

PubMed

The physical description of the passage of heavy ions in tissue and shielding materials is of interest in radiobiology, cancer therapy and space exploration, including a human mission to Mars. Galactic cosmic rays (GCRs) consist of a large number of ion types and energies. Energy loss processes occur continuously along the path of heavy ions and are well described by the linear energy transfer (LET), straggling and multiple scattering algorithms. Nuclear interactions lead to much larger energy deposition than atomic-molecular collisions and alter the composition of heavy ion beams while producing secondary nuclei often in high multiplicity events. The major nuclear interaction processes of importance for describing heavy ion beams was reviewed, including nuclear fragmentation, elastic scattering and knockout-cascade processes. The quantum multiple scattering fragmentation model is shown to be in excellent agreement with available experimental data for nuclear fragmentation cross sections and is studied for application to thick target experiments. A new computer model, which was developed for the description of biophysical events from heavy ion beams at the NASA Space Radiation Laboratory (NSRL), called the GCR Event Risk-Based Model (GERMcode) is described. PMID:21242169

Cucinotta, Francis A; Plante, Ianik; Ponomarev, Artem L; Kim, Myung-Hee Y

2011-02-01

4

GCR Environmental Models III: GCR Model Validation and Propagated Uncertainties in Effective Dose  

NASA Technical Reports Server (NTRS)

This is the last of three papers focused on quantifying the uncertainty associated with galactic cosmic rays (GCR) models used for space radiation shielding applications. In the first paper, it was found that GCR ions with Z>2 and boundary energy below 500 MeV/nucleon induce less than 5% of the total effective dose behind shielding. This is an important finding since GCR model development and validation have been heavily biased toward Advanced Composition Explorer/Cosmic Ray Isotope Spectrometer measurements below 500 MeV/nucleon. Weights were also developed that quantify the relative contribution of defined GCR energy and charge groups to effective dose behind shielding. In the second paper, it was shown that these weights could be used to efficiently propagate GCR model uncertainties into effective dose behind shielding. In this work, uncertainties are quantified for a few commonly used GCR models. A validation metric is developed that accounts for measurements uncertainty, and the metric is coupled to the fast uncertainty propagation method. For this work, the Badhwar-O'Neill (BON) 2010 and 2011 and the Matthia GCR models are compared to an extensive measurement database. It is shown that BON2011 systematically overestimates heavy ion fluxes in the range 0.5-4 GeV/nucleon. The BON2010 and BON2011 also show moderate and large errors in reproducing past solar activity near the 2000 solar maximum and 2010 solar minimum. It is found that all three models induce relative errors in effective dose in the interval [-20%, 20%] at a 68% confidence level. The BON2010 and Matthia models are found to have similar overall uncertainty estimates and are preferred for space radiation shielding applications.

Slaba, Tony C.; Xu, Xiaojing; Blattnig, Steve R.; Norman, Ryan B.

2014-01-01

5

A Stochastic Model of Space Radiation Transport as a Tool in the Development of Time-Dependent Risk Assessment  

NASA Technical Reports Server (NTRS)

A new computer model, the GCR Event-based Risk Model code (GERMcode), was developed to describe biophysical events from high-energy protons and heavy ions that have been studied at the NASA Space Radiation Laboratory (NSRL) [1] for the purpose of simulating space radiation biological effects. In the GERMcode, the biophysical description of the passage of heavy ions in tissue and shielding materials is made with a stochastic approach that includes both ion track structure and nuclear interactions. The GERMcode accounts for the major nuclear interaction processes of importance for describing heavy ion beams, including nuclear fragmentation, elastic scattering, and knockout-cascade processes by using the quantum multiple scattering fragmentation (QMSFRG) model [2]. The QMSFRG model has been shown to be in excellent agreement with available experimental data for nuclear fragmentation cross sections

Kim, Myung-Hee Y.; Nounu, Hatem N.; Ponomarev, Artem L.; Cucinotta, Francis A.

2011-01-01

6

Isotopic Effects in Nuclear Fragmentation and GCR Transport Problems  

NASA Technical Reports Server (NTRS)

Improving the accuracy of the galactic cosmic ray (GCR) environment and transport models is an important goal in preparing for studies of the projected risks and the efficiency of potential mitigations methods for space exploration. In this paper we consider the effects of the isotopic composition of the primary cosmic rays and the isotopic dependence of nuclear fragmentation cross sections on GCR transport models. Measurements are used to describe the isotopic composition of the GCR including their modulation throughout the solar cycle. The quantum multiple-scattering approach to nuclear fragmentation (QMSFRG) is used as the data base generator in order to accurately describe the odd-even effect in fragment production. Using the Badhwar and O'Neill GCR model, the QMSFRG model and the HZETRN transport code, the effects of the isotopic dependence of the primary GCR composition and on fragment production for transport problems is described for a complete GCR isotopic-grid. The principle finding of this study is that large errors ( 100%) will occur in the mass-flux spectra when comparing the complete isotopic-grid (141 ions) to a reduced isotopic-grid (59 ions), however less significant errors 30%) occur in the elemental-flux spectra. Because the full isotopic-grid is readily handled on small computer work-stations, it is recommended that they be used for future GCR studies.

Cucinotta, Francis A.

2002-01-01

7

GCR-ORR LOOP NO. 2 FILTER TESTS. PART II  

Microsoft Academic Search

Tests of Cambridge absolute filters, Model Sl-071, specified for use in ; the GCR-ORR Loop No. 2 as full-flow, primary coolant fiiters were completed. ; kD.O.P\\/ (dioctylphthalate) efficiency tests were performed on three filters in ; the as-received condition, on two filters following canning and thermal cycling, ; and on one of the canned fiIters following bsking out. None of

F. A. Flint; A. M. Smith

1962-01-01

8

Improvements to neutron data relevant to GCR transport  

Microsoft Academic Search

There is an existing database of secondary neutron production cross sections and thick-target yields from heavy-ion interactions that have been used extensively for benchmarking transport model calculations such as PHITS, MARS, FLUKA, GEANT4, HETC-HEDS, MCNPX-HI, and SHIELD-HIT. These data are especially relevant to the development of transport models used to simulate Galactic Cosmic Ray (GCR) transport through shielding. Improvements have

L. Heilbronn; Lawrence Townsend; Hiroshi Iwase; Takashi Nakamura

2009-01-01

9

Asynchronous frameless event-based optical flow.  

PubMed

This paper introduces a process to compute optical flow using an asynchronous event-based retina at high speed and low computational load. A new generation of artificial vision sensors has now started to rely on biologically inspired designs for light acquisition. Biological retinas, and their artificial counterparts, are totally asynchronous and data driven and rely on a paradigm of light acquisition radically different from most of the currently used frame-grabber technologies. This paper introduces a framework for processing visual data using asynchronous event-based acquisition, providing a method for the evaluation of optical flow. The paper shows that current limitations of optical flow computation can be overcome by using event-based visual acquisition, where high data sparseness and high temporal resolution permit the computation of optical flow with micro-second accuracy and at very low computational cost. PMID:22154354

Benosman, Ryad; Ieng, Sio-Hoi; Clercq, Charles; Bartolozzi, Chiara; Srinivasan, Mandyam

2012-03-01

10

Event-based control for memristive systems  

NASA Astrophysics Data System (ADS)

This paper studies the event-based control for memristive systems. Consider the state-dependent properties of the memristor, a new fuzzy model employing parallel distributed compensation (PDC) gives a new way to linearize complicated memristive system with only two subsystems. As the existence of uncertainties of memristor and to reduce the amount of communication, event-based control algorithm to stabilize memristive systems and extend the results to systems with signal quantization and networked induced delays. Through the fuzzy modeling and distributed event-based control, there are three main advantages: (1) only two linear subsystems are considered to reduce the numbers of fuzzy rules from 2n to 2×n as for traditional Takagi-Sugeno fuzzy model, n is the number of memristive subsystems; (2) the memristive subsystem is triggered at its own event time, which reduces communication burdens and lowers the controller updating frequency; (3) the effects of quantization and time delays are taken into account.

Wen, Shiping; Zeng, Zhigang; Huang, Tingwen

2014-10-01

11

Model Estimated GCR Particle Flux Variation - Assessment with CRIS Data  

NASA Astrophysics Data System (ADS)

We present model calculated particle flux as a function of time during the current solar cycle along with the comparisons from the ACE/CRIS data and the Mars/MARIE data. In our model calculations we make use of the NASA's HZETRN (High Z and Energy Transport) code along with the nuclear fragmentation cross sections that are described by the quantum multiple scattering (QMSFRG) model. The time dependant variation of the GCR environment is derived making use of the solar modulation potential, phi. For the past ten years, Advanced Composition Explorer (ACE) has been in orbit at the Sun- Earth libration point (L1). Data from the Cosmic Ray Isotope Spectrometer (CRIS) instrument onboard the ACE spacecraft has been available from 1997 through the present time. Our model calculated particle flux showed high degree of correlation during the earlier phase of the current solar cycle (2003) in the lower Z region within 15

Saganti, Premkumar

12

Interplanetary CME Effects on the Short-Period Variability in the GCR Flux  

NASA Astrophysics Data System (ADS)

We examine several cases of short-period variability in the GCR flux in the solar wind and in the magnetosphere using background channels in several spacecraft including Polar, ACE, and INTEGRAL. INTEGRAL in particular offers unprecedented resolution of Forbush decreases with GCR count rates exceeding 10^5 counts/s. We find correlations between the GCR fine scale structure and the local solar wind magnetic field topology. Often these periods occur in and around the time of the passage of an interplanetary coronal mass ejection (ICME) and its substructures. The fine structures in the GCR intensities along with the Forbush decrease caused by the ICME are propagated outward with very little change from L1 to the Earth indicating that parcels of solar wind are transporting the GCR population outward in the heliosphere. This solar wind convection of GCR fine structure is observed for both increases and decreases in GCR intensity and the fine-structure increases and decreases are bracketed by solar wind magnetic field discontinuities within the ICME. Similar to the dispersionless modulation of the electron heat flux, which is an indicator of changes in magnetic field topology, the fine structures in the GCR observations show that the intensity levels in the GCR flux may undergo a similar partitioning associated with local changes observed in the interplanetary magnetic field. We also find this local field topology affects the energetic electron population (>500 keV) in the magnetosphere and explore such observations in detail. Undoubtedly, the high-resolution measurements made available by the background channels from the INTEGRAL, Polar, and ACE spacecraft give us an unprecedented view into the microphysical processes of energetic particle transport and quite possibly the magnetospheric response to the high frequency content of the interplanetary medium.

Mulligan, T.; Blake, J. B.; Shaul, D. A.; Quenby, J. J.

2009-12-01

13

The Role of Gcr1p in the Transcriptional Activation of Glycolytic Genes in Yeast Saccharomyces Cerevisiae  

PubMed Central

To study the interdependence of Gcr1p and Rap1p, we prepared a series of synthetic regulatory sequences that contained various numbers and combinations of CT-boxes (Gcr1p-binding sites) and RPG-boxes (Rap1p-binding sites). The ability of the synthetic oligonucleotides to function as regulatory sequences was tested using an ENO1-lacZ reporter gene. As observed previously, synthetic oligonucleotides containing both CT- and RPG-boxes conferred strong UAS activity. Likewise, a lone CT-box did not show any UAS activity. By contrast, oligonucleotides containing tandem CT-boxes but no RPG-box conferred strong promoter activity. This UAS activity was not dependent on position or orientation of the oligonucleotides in the 5' noncoding region. However, it was dependent on both GCR1 and GCR2. These results suggest that the ability of Gcr1p to bind Gcr1p-binding sites in vivo is not absolutely dependent on Rap1p. Eleven independent mutants of GCR1 were isolated that conferred weak UAS activity to a single CT-box. Five mutants had single mutations in Gcr1p's DNA-binding domain and displayed slightly higher affinity for the CT-box. These results support the hypothesis that Gcr1p and Gcr2p play the central role in glycolytic gene expression and that the function of Rap1p is to facilitate the binding of Gcr1p to its target.

Uemura, H.; Koshio, M.; Inoue, Y.; Lopez, M. C.; Baker, H. V.

1997-01-01

14

Event-Based Science: Remote Sensing Activities  

NSDL National Science Digital Library

Event-Based Science is a new way to teach science by using newsworthy events to establish the relevance of science topics. Interviews, photographs, web pages, and inquiry-based science activities create a desire to know more about these topics. This collection of activities deals with such topics as damage to agriculture caused by drought, the recovery of forests after a fire, and flooding and the migration of river channels. There are also activities on earthquake hazards, hurricane tracking, the impacts of oil spills, and how to plan an escape route to avoid a volcanic mudflow. Each of these activities uses NASA imagery, in particular LandSat images.

2007-03-15

15

Landscape of international event-based biosurveillance.  

PubMed

Event-based biosurveillance is a scientific discipline in which diverse sources of data, many of which are available from the Internet, are characterized prospectively to provide information on infectious disease events. Biosurveillance complements traditional public health surveillance to provide both early warning of infectious disease events and situational awareness. The Global Health Security Action Group of the Global Health Security Initiative is developing a biosurveillance capability that integrates and leverages component systems from member nations. This work discusses these biosurveillance systems and identifies needed future studies. PMID:22460393

Hartley, Dm; Nelson, Np; Walters, R; Arthur, R; Yangarber, R; Madoff, L; Linge, Jp; Mawudeku, A; Collier, N; Brownstein, Js; Thinus, G; Lightfoot, N

2010-01-01

16

A framework for event-based software integration  

Microsoft Academic Search

Although event-based software integration is one of the most prevalent approaches to loose integration, no consistent model for describing it exists. As a result, there is no uniform way to discuss event-based integration, compare approaches and implementations, specify new event-based approaches, or match user requirements with the capabilities of event-based integration systems. We attempt to address these shortcomings by specifying

Daniel J. Barrett; Lori A. Clarke; Peri L. Tarr; Alexander E. Wise

1996-01-01

17

Energetic particles in the heliosphere and GCR modulation: Reviewing of SH-posters  

NASA Astrophysics Data System (ADS)

This rapporteur paper addresses the SH poster session titled "Energetic particles in the heliosphere (solar and anomalous CRs, GCR modulation)" of the 23rd European Cosmic Ray Symposium (ECRS) and the 32nd Russian Cosmic Ray Conference (RCRC). The 65 posters presented are tentatively divided into five sections: Instruments and Methods; Solar Energetic Particles; Short Term Variations; Long Term Variations; Heliosphere.

Struminsky, Alexei

2013-02-01

18

The tribological behaviour of GCr15 bearing steel implanted with cerium  

Microsoft Academic Search

The tribological behaviour of unimplanted and cerium ion implanted GCr15 bearing steel with three kinds of dosages was investigated with an SRV wear tester and dynamic-static friction precision measurement apparatus under dry friction conditions. The tribological behaviour of the samples was also evaluated under liquid paraffin lubrication. The test results showed that the wear resistance of the implanted specimens increased

Yafeng Lian; Qunji Xue; Hanqing Wang

1995-01-01

19

Efficient transcription of the glycolytic gene ADH1 and three translational component genes requires the GCR1 product, which can act through TUF/GRF/RAP binding sites.  

PubMed Central

Glycolytic gene expression in Saccharomyces cerevisiae is thought to be activated by the GCR and TUF proteins. We tested the hypothesis that GCR function is mediated by TUF/GRF/RAP binding sites (UASRPG elements). We found that UASRPG-dependent activation of a heterologous gene and transcription of ADH1, TEF1, TEF2, and RP59 were sensitive to GCR1 disruption. GCR is not required for TUF/GRF/RAP expression or in vitro DNA-binding activity. Images

Santangelo, G M; Tornow, J

1990-01-01

20

Taxonomy of Distributed Event-Based Programming Systems  

Microsoft Academic Search

Event-based middleware is currently being applied for application component integration in a range of application domains. As a result, a variety of event services have been proposed to address different requirements. In order to aid the understanding of the relationships between these systems, this paper presents a taxonomy of distributed event-based programming systems. The taxonomy is structured as a hierarchy

René Meier; Vinny Cahill

2002-01-01

21

Discrete-event based simulation conceptual modeling of systems biology  

Microsoft Academic Search

The protein production from DNA to protein via RNA is a very complicated process, which could be called central dogma. In this paper, we used event based simulation to model, simulate, analyze and specify the three main processes that are involved in the process of protein production: replication, transcription, and translation. The whole control flow of event-based simulation is composed

Joe W. Yeol; Issac Barjis; Yeong S. Ryu; Joseph Barjis

2005-01-01

22

Observations of Dispersionless Modulation in the GCR Intensity in Association with Changes in the Suprathermal Electron Heat Flux  

NASA Astrophysics Data System (ADS)

Focusing upon the GCR intensity within a three-day interval during an unusually active period in the solar wind from 19 August 2006 to 21 August 2006 reveals many intensity variations in the GCR on a variety of timescales and amplitudes. These intensity variations are greater than the 3ó error in all the datasets used from Wind, ACE, Polar and INTEGRAL. The fine structures in the GCR intensities along with the Forbush decrease are propagated outward from ACE to the Earth with very little change. The solar wind speed stays relatively constant during these periods indicating that parcels of solar wind are transporting the GCR population outward in the heliosphere. This solar wind convection of GCR fine structure is observed for both increases and decreases in GCR intensity and the fine-structure increases and decreases are bracketed by solar wind magnetic field discontinuities associated with ICME magnetosheath regions, clearly seen as discontinuous rotations of the field components at ACE and at Wind. Interestingly, the electron heat flux shows different flux tube connectivity also associated with the different regions of the ICME and magnetosheath. Gosling et al., [2004] first discussed the idea that solar energetic particle intensities commonly undergo dispersionless modulation in direct association with discontinuous changes in the solar wind electron strahl. The observations show that the intensity levels in the GCR flux may undergo a similar partitioning, possibly due to the different magnetic field regions having differing magnetic topologies. This new observation of GCR intensity being modulated by the local magnetic field topology will be compared to previous studies of GCR intensity anti-correlation with the interplanetary magnetic field strength [Burlaga et al., 1993; Burlaga and Ness, 1998] and discussed in more detail. Such comparisons will lead to further understanding of the underlying physics of energetic particle transport though the interplanetary medium.

Mulligan, T.; Blake, J. B.; Shaul, D. A.; Quenby, J. J.; Leske, R. A.; Mewaldt, R. A.

2008-12-01

23

Some recent progress on identifying and modelling a relationship between the GCR flux and climate  

NASA Astrophysics Data System (ADS)

A relationship is identified between the largest (top 5%) most rapid global increases in ISCCP retrieved IR cloud cover and statistically significant increases in the rate of galactic cosmic ray (GCR) flux across the globe; the cloud changes correspond both temporally and spatially to significant variations in a range of NCEP/NCAR reanalysis parameters, including: air temper-ature and pressure. We suggest that because the influence of GCR on cloud cover is likely a second order effect, the use of datasets internal to the climate system has allowed us to identify a strong relationship where previously none has been found. The cloud-climate interaction ob-served indicates an indirect forcing mechanism operating via an alteration to polar circulation. An attempt has been made to simulate the observed climate anomalies by modifying cloud cover directly within a general circulation model (GCM), thus allowing us to comment on the casual relationship between the observed cloud/climate changes.

Laken, Benjamin; Kniveton, Dominic

24

Multi-field coupled numerical simulation of hot reversible rolling process of GCr15 steel rod  

NASA Astrophysics Data System (ADS)

In this paper, based on rolling technology of hot reversible rolling mill, a multi-filed coupled finite element (FE) model of hot reversible rolling process of large dimension cross-section GCr15 steel rod is established. Thermal, mechanical and microstructural phenomena during the rolling process are coupled in the model. By employing grain growth experiment, double and single hit hot compression experiments, the austenite grain size growth mathematical model and recrystallization behavior mathematical models are determined. And a designed subprogram is coupled in the FE model. Actual hot reversible rolling process of GCr15 steel is simulated using the model and the distribution and evolution of different filed-variables, such as temperature, effective strain and austenite grain size are obtained. To verify the model predictions, hot rolling experiments are carried out and the temperature and microstructure of the rolling metal are compared with the predicted results. The comparison between the two sets of data shows a good agreement.

Gu, Sendong; Zhang, Liwen; Ruan, Jinhua; Mei, Hongyu; Zhen, Yu; Shi, Xinhua

2013-05-01

25

Microstructure and continuous cooling transformation thermograms of spray formed GCr15 steel  

Microsoft Academic Search

Microstructure of the spray formed GCr15 steel was observed by optical microscopy and transmission electron microscopy, showing fine pearlite with the interspacing of 85 nm in as-sprayed samples and martensite of the width of 0.35 ?m in oil-quenched samples. Two formulae correlating the hardness with the interspacing of the pearlite and the width of the martensite, respectively were derived on

Jing Guo Zhang; De Sheng Sun; Hai Sheng Shi; Han Bin Xu; Jian Shen Wu; Xing Fang Wu

2002-01-01

26

HZETRN: neutron and proton production in quasi-elastic scattering of GCR heavy-ions  

NASA Technical Reports Server (NTRS)

The development of transport models for radiation shielding design and evaluation has provided a series of deterministic computer codes that describe galactic cosmic radiation (GCR), solar particle events, and experimental beams at particle accelerators. These codes continue to be modified to accommodate new theory and improvements to the particle interaction database (Cucinotta et al., 1994, NASA Technical Paper 3472, US Government Printing Office, Washington DC). The solution employed by the heavy-ion transport code HZETRN was derived with the assumption that nuclear fragments are emitted with the same velocity as the incident ion through velocity conserving nuclear interactions. This paper presents a version of the HZETRN transport code that provides a more realistic distribution of the energy of protons and neutrons emitted from GCR interactions in shields. This study shows that the expected GCR dose equivalent is lower than previously calculated for water shields that are less than 110 g cm-2 thick. Calculations of neutron energy spectra in low Earth orbit indicate substantial contributions from relativistic neutrons. c2001 Elsevier Science Ltd. All rights reseved.

Shavers, M. R.; Cucinotta, F. A.; Wilson, J. W.

2001-01-01

27

HZETRN: neutron and proton production in quasi-elastic scattering of GCR heavy-ions.  

PubMed

The development of transport models for radiation shielding design and evaluation has provided a series of deterministic computer codes that describe galactic cosmic radiation (GCR), solar particle events, and experimental beams at particle accelerators. These codes continue to be modified to accommodate new theory and improvements to the particle interaction database (Cucinotta et al., 1994, NASA Technical Paper 3472, US Government Printing Office, Washington DC). The solution employed by the heavy-ion transport code HZETRN was derived with the assumption that nuclear fragments are emitted with the same velocity as the incident ion through velocity conserving nuclear interactions. This paper presents a version of the HZETRN transport code that provides a more realistic distribution of the energy of protons and neutrons emitted from GCR interactions in shields. This study shows that the expected GCR dose equivalent is lower than previously calculated for water shields that are less than 110 g cm-2 thick. Calculations of neutron energy spectra in low Earth orbit indicate substantial contributions from relativistic neutrons. PMID:11855417

Shavers, M R; Cucinotta, F A; Wilson, J W

2001-06-01

28

Taxonomy of Distributed Event-Based Programming Systems  

Microsoft Academic Search

Abstract This paper presents a survey of existing event systems structured as a taxonomy,of distributed event-based programming,systems. Our taxonomy,identifies a set of fundamental properties of event-based programming,systems and categorizes them according to the event model and event service criteria. The event service is further classified according to its organization and interaction model, as well as other functional and non-functional features.

René Meier; Vinny Cahill

2005-01-01

29

Asynchronous visual event-based time-to-contact.  

PubMed

Reliable and fast sensing of the environment is a fundamental requirement for autonomous mobile robotic platforms. Unfortunately, the frame-based acquisition paradigm at the basis of main stream artificial perceptive systems is limited by low temporal dynamics and redundant data flow, leading to high computational costs. Hence, conventional sensing and relative computation are obviously incompatible with the design of high speed sensor-based reactive control for mobile applications, that pose strict limits on energy consumption and computational load. This paper introduces a fast obstacle avoidance method based on the output of an asynchronous event-based time encoded imaging sensor. The proposed method relies on an event-based Time To Contact (TTC) computation based on visual event-based motion flows. The approach is event-based in the sense that every incoming event adds to the computation process thus allowing fast avoidance responses. The method is validated indoor on a mobile robot, comparing the event-based TTC with a laser range finder TTC, showing that event-based sensing offers new perspectives for mobile robotics sensing. PMID:24570652

Clady, Xavier; Clercq, Charles; Ieng, Sio-Hoi; Houseini, Fouzhan; Randazzo, Marco; Natale, Lorenzo; Bartolozzi, Chiara; Benosman, Ryad

2014-01-01

30

Event-based prospective memory in the rat.  

PubMed

People plan to act in the future when an appropriate event occurs, a capacity known as event-based prospective memory. Prospective memory involves forming a representation of a planned future action, subsequently inactivating the representation, and ultimately reactivating it at an appropriate point in the future. Recent studies suggest that monkeys, chimpanzees, and rats display elements of prospective memory, but it is uncertain if the full sequence (activation-inactivation-reactivation) that occurs in humans also occurs in nonhumans. Here, we asked if rats exhibit event-based prospective memory. Rats completed an ongoing temporal-discrimination task while waiting for a large meal. To promote the use of event-based prospective memory, we created an event (tone pulses) that provided information that the meal could be obtained soon. Event-based prospective memory was suggested by the dramatic decline in ongoing-task performance after the event, with excellent performance at other times. To document that the event initiated memory activation, we arranged for the event to occur at novel times. Finally, multiple, repeated presentations of the event on the same day demonstrate that rats inactivate and reactivate the memory representation in an on-demand, event-based fashion. Development of an animal model of prospective memory may be valuable to probe the biological underpinnings of memory disorders. PMID:23727093

Wilson, A George; Pizzo, Matthew J; Crystal, Jonathon D

2013-06-17

31

Event-based prospective memory in the rat  

PubMed Central

Summary People plan to act in the future when an appropriate event occurs, a capacity known as event-based prospective memory [1]. Prospective memory involves forming a representation of a planned future action, subsequently inactivating the representation, and ultimately reactivating it at an appropriate point in the future. Recent studies suggest that monkeys, chimpanzees, and rats display elements of prospective memory [2–5], but it is uncertain if the full sequence (activation-inactivation-reactivation) that occurs in humans also occurs in nonhumans [6–8]. Here we asked if rats exhibit event-based prospective memory. Rats completed an ongoing temporal-discrimination task while waiting for a large meal. To promote the use of event-based prospective memory, an event (tone-pulses) provided information that the meal could be obtained soon. Event-based prospective memory was suggested by the dramatic decline in ongoing-task performance after the event, with excellent performance at other times. To document that the event initiated memory activation, the event occurred at novel times. Finally, multiple, repeated presentations of the event on the same day demonstrate that rats inactivate and reactivate the memory representation in an on-demand, event-based fashion. Development of an animal model of prospective memory may be valuable to probe the biological underpinnings of memory disorders [7, 9].

Wilson, A. George; Pizzo, Matthew J.; Crystal, Jonathon D.

2013-01-01

32

Event based and time based prospective memory in Parkinson's disease  

PubMed Central

Background: Patients with Parkinson's disease have been reported to have retrospective memory impairment, while prospective memory, which is memory for actions to be performed in the future, has not yet been investigated. Objective: To investigate the prospective memory of patients with Parkinson's disease. Methods: Twenty Parkinson's disease patients and 20 age matched normal controls were given event based and time based prospective memory tasks. In the event based prospective memory task, the subject was asked to perform an action whenever particular words were presented. In the time based prospective memory task, the subject was asked to perform an action at certain times. Results: The Parkinson's disease patients were impaired on the event based prospective memory task but not on the time based prospective memory task. The impairment of the Parkinson's disease patients on the event based prospective memory task was not the result of their forgetting the content of the prospective memory instructions, but the result of their failure to retrieve it spontaneously when the target words appeared. Conclusions: These results suggest that event based prospective memory is impaired in patients with Parkinson's disease, presumably relating to frontal lobe dysfunction.

Katai, S; Maruyama, T; Hashimoto, T; Ikeda, S

2003-01-01

33

Galactic Cosmic Ray (GCR) Model of Titan and Formation of HCNO Exobiological Molecules  

NASA Astrophysics Data System (ADS)

Saturn as a system has two very exotic moons Titan and Enceladus. Space radiation effects at both moons, and as coupled by the Saturn magnetosphere, could lead to the evolution of exobiological models at Titan composed of HCNO molecules. At Titan Cassini discovered that 1) keV oxygen ions, evidently from Enceladus, are bombarding Titan’s upper atmosphere (Hartle et al., 2006a,b) and 2) heavy positive and negative ions exist in significant abundances within Titan’s upper atmosphere (Coates et al., 2007). Polycyclic Aromatic Hydrocarbons (PAHs) and fullerenes could form in Titan’s ionosphere. Laboratory measurements indicate that fullerenes, which are hollow carbon shells, can trap the keV oxygen ions. Clustering of the fullerenes with PAHs and the dominant nitrogen molecules could form larger aerosols enriched in trapped oxygen. Aerosol precipitation could then convey these chemically complex structures deeper into the atmosphere and to the moon surface. We estimate that GCR irradiation should dominate the chemical processing of the aerosols on the surface into more complex organic forms such as tholins and amino acids. To further quantify our results, we have developed an advanced model of GCR interaction with Titan’s atmosphere, surface and sub-surface. The model shows dose rates ~ 8x10-6 ergs/cm2/s at the surface which is ~ 4.2x10-9 erg/gm/s for tholin mass density ~ 1.8 gm/cm3. The GCR are found to penetrate ~ 50-100 m below the surface and may therefore also reach the bottom of Titan’s methane-ethane lakes. Reggie Hudson et al. (2008) showed that G-factor ~ 0.001 for Glycine. They used pure Acetonitrile CH3CN ices with very small water levels ~ 0.01% for O. So using G ~ 0.001 and GCR surface energy flux noted above at Titan’s surface we estimate abundance levels ~ 2-10 ppb of amino acids such as Glycine over 450 Myr period. Therefore, we conclude that this synergy of Saturn system, exogenic irradiation, and molecular processes provide a potential pathway for accumulation of prebiotic chemicals on the surface of Titan.

Sittler, Edward C.; Cooper, J. F.

2014-01-01

34

Tabular Interface for Automated Verification of Event-Based Dialogs.  

National Technical Information Service (NTIS)

In this report, we investigate the feasibility of a tabular interface for the specification and analysis of event-based dialogues. These dialogues are used to define high-level descriptions of interactive systems, and they are based on Olsen's Proposition...

H. M. Wang G. Abowd

1994-01-01

35

Remote sensing in the event-based science classroom  

Microsoft Academic Search

Event-Based Science (EBS) is a modular middle school science curriculum that is created by a partnership among Montgomery County Public Schools (Rockville, MD), USA Today, NBC News, CNN, and federal science agencies. EBS was funded by a grant from the National Science Foundation. The National Aeronautics and Space Administration (NASA) is supporting development of remote-sensing activities that allow middle school

R. G. Wright; D. K. Hall

2000-01-01

36

A Multinomial Model of Event-Based Prospective Memory  

ERIC Educational Resources Information Center

Prospective memory is remembering to perform an action in the future. The authors introduce the 1st formal model of event-based prospective memory, namely, a multinomial model that includes 2 separate parameters related to prospective memory processes. The 1st measures preparatory attentional processes, and the 2nd measures retrospective memory…

Smith, Rebekah E.; Bayen, Ute J.

2004-01-01

37

Variability in the GCR Count Rate as Measured by the CRaTER Instrument on LRO  

NASA Astrophysics Data System (ADS)

The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) is currently orbiting the Moon onboard NASA's Lunar Reconnaissance Orbiter (LRO). CRaTER is composed of a stack of 3 pairs of axially-aligned solid-state Silicon detectors which surround 2 sections of Tissue Equivalent Plastic. Particles that have enough energy to penetrate the outer skin of the instrument (about 10 MeV for protons) are measured at each detector pair as they traverse the length of the instrument. The particle population that produces a signal in CRaTER normally consists of both solar energetic particles and Galactic Cosmic Rays (GCR). Due to the low level of solar activity during the mission thus far, CRaTER's measurements consist almost entirely of GCR. In this paper we investigate spatial variabilities in the count rate during the first few months of the mission that could be due to lunar phase, lunar latitude/longitude, eclipses and look direction. Possible sources of temporal variability will also be investigated.

Case, A. W.; Spence, H. E.; Golightly, M. J.; Kasper, J. C.; Blake, J. B.; Mazur, J. E.; Townsend, L. W.

2009-12-01

38

Miniaturized Hollow-Waveguide Gas Correlation Radiometer (GCR) for Trace Gas Detection in the Martian Atmosphere  

NASA Technical Reports Server (NTRS)

Gas correlation radiometry (GCR) has been shown to be a sensitive and versatile method for detecting trace gases in Earth's atmosphere. Here, we present a miniaturized and simplified version of this instrument capable of mapping multiple trace gases and identifying active regions on the Mars surface. Reduction of the size and mass of the GCR instrument has been achieved by implementing a lightweight, 1 mm inner diameter hollow-core optical fiber (hollow waveguide) for the gas correlation cell. Based on a comparison with an Earth orbiting CO2 gas correlation instrument, replacement of the 10 meter mUltipass cell with hollow waveguide of equivalent pathlength reduces the cell mass from approx 150 kg to approx 0.5 kg, and reduces the volume from 1.9 m x 1.3 m x 0.86 m to a small bundle of fiber coils approximately I meter in diameter by 0.05 m in height (mass and volume reductions of >99%). This modular instrument technique can be expanded to include measurements of additional species of interest including nitrous oxide (N2O), hydrogen sulfide (H2S), methanol (CH3OH), and sulfur dioxide (SO2), as well as carbon dioxide (CO2) for a simultaneous measure of mass balance.

Wilson, Emily L.; Georgieva, E. M.; Melroy, H. R.

2012-01-01

39

Comparison of Transport Codes, HZETRN, HETC and FLUKA, Using 1977 GCR Solar Minimum Spectra  

NASA Technical Reports Server (NTRS)

The HZETRN deterministic radiation transport code is one of several tools developed to analyze the effects of harmful galactic cosmic rays (GCR) and solar particle events (SPE) on mission planning, astronaut shielding and instrumentation. This paper is a comparison study involving the two Monte Carlo transport codes, HETC-HEDS and FLUKA, and the deterministic transport code, HZETRN. Each code is used to transport ions from the 1977 solar minimum GCR spectrum impinging upon a 20 g/cm2 Aluminum slab followed by a 30 g/cm2 water slab. This research is part of a systematic effort of verification and validation to quantify the accuracy of HZETRN and determine areas where it can be improved. Comparisons of dose and dose equivalent values at various depths in the water slab are presented in this report. This is followed by a comparison of the proton fluxes, and the forward, backward and total neutron fluxes at various depths in the water slab. Comparisons of the secondary light ion 2H, 3H, 3He and 4He fluxes are also examined.

Heinbockel, John H.; Slaba, Tony C.; Tripathi, Ram K.; Blattnig, Steve R.; Norbury, John W.; Badavi, Francis F.; Townsend, Lawrence W.; Handler, Thomas; Gabriel, Tony A.; Pinsky, Lawrence S.; Reddell, Brandon; Aumann, Aric R.

2009-01-01

40

Mars Science Laboratory; A Model for Event-Based EPO  

NASA Astrophysics Data System (ADS)

The NASA Mars Science Laboratory (MSL) and its Curiosity Rover, a part of NASA's Mars Exploration Program, represent the most ambitious undertaking to date to explore the red planet. MSL/Curiosity was designed primarily to determine whether Mars ever had an environment capable of supporting microbial life. NASA's MSL education program was designed to take advantage of existing, highly successful event based education programs to communicate Mars science and education themes to worldwide audiences through live webcasts, video interviews with scientists, TV broadcasts, professional development for teachers, and the latest social media frameworks. We report here on the success of the MSL education program and discuss how this methodological framework can be used to enhance other event based education programs.

Mayo, Louis; Lewis, E.; Cline, T.; Stephenson, B.; Erickson, K.; Ng, C.

2012-10-01

41

ADEES: An Adaptable and Extensible Event Based Infrastructure  

Microsoft Academic Search

This paper describes ADEES, an open and evolutionary event-based architecture to develop complex distributed information systems.\\u000a Different from most existing event supports that provide limited event description models and fixed management models, ADEES\\u000a can be extendedandcustomizedon a per-application basis. It is not another “one-size-fits-all” event manager! It is usedto\\u000a generate event managers adopted by components to produce and consume events

Genoveva Vargas-solar; Christine Collet

2002-01-01

42

Characterising a novel interface for event-based haptic grasping  

Microsoft Academic Search

This paper investigates the capacity of a light-weight haptic grasping interface to convey event-based high-frequency transient forces within a virtual environment. The addition of vibrations based on contact with real-world objects over traditional position-based feedback has shown to significantly enhance the feel of hard surfaces. We describe the design of our prototype grasping system, and experimentally demonstrate the utility of

Zoran Najdovski; Saeid Nahavandi

2009-01-01

43

A Multinomial Model of Event-Based Prospective Memory  

Microsoft Academic Search

Prospective memory is remembering to perform an action in the future. The authors introduce the 1st formal model of event-based prospective memory, namely, a multinomial model that includes 2 separate parameters related to prospective memory processes. The 1st measures preparatory attentional processes, and the 2nd measures retrospective memory processes. The model was validated in 4 experiments. Manipulations of instructions to

Rebekah E. Smith; Ute J. Bayen

2004-01-01

44

Event-based imaging with active illumination in sensor networks  

Microsoft Academic Search

Abstract—We discuss a distributed imaging architecture with active illumination for sensor network applications. An event -based CMOS imager is employed at the sensor level, to convert light intensity at each pixel into pulse density modulated stream of address events. The wireless nodes are commercial off-the -shelf Motes. Energy-aware communication is implemented at the sensor level byemploying an eventbased readout. Additional

Eugenio Culurciello; Thiago Teixeira; Andreas G. Andreou

2005-01-01

45

Secondary Cosmic Ray Particles Due to GCR Interactions in the Earth's Atmosphere  

SciTech Connect

Primary GCR interact with the Earth's atmosphere originating atmospheric showers, thus giving rise to fluxes of secondary particles in the atmosphere. Electromagnetic and hadronic interactions interplay in the production of these particles, whose detection is performed by means of complementary techniques in different energy ranges and at different depths in the atmosphere, down to the Earth's surface. Monte Carlo codes are essential calculation tools which can describe the complexity of the physics of these phenomena, thus allowing the analysis of experimental data. However, these codes are affected by important uncertainties, concerning, in particular, hadronic physics at high energy. In this paper we shall report some results concerning inclusive particle fluxes and atmospheric shower properties as obtained using the FLUKA transport and interaction code. Some emphasis will also be given to the validation of the physics models of FLUKA involved in these calculations.

Battistoni, G.; /Milan U. /INFN, Milan; Cerutti, F.; /CERN; Fasso, A.; /SLAC; Ferrari, A.; /CERN; Garzelli, M.V.; /Milan U. /INFN, Milan; Lantz, M.; /Goteborg, ITP; Muraro, S. /Milan U. /INFN, Milan; Pinsky, L.S.; /Houston U.; Ranft, J.; /Siegen U.; Roesler, S.; /CERN; Sala, P.R.; /Milan U. /INFN, Milan; ,

2009-06-16

46

Secondary Cosmic Ray Particles due to GCR Interactions in the Earth's Atmosphere  

SciTech Connect

Primary GCR interact with the Earth's atmosphere originating atmospheric showers, thus giving rise to fluxes of secondary particles in the atmosphere. Electromagnetic and hadronic interactions interplay in the production of these particles, whose detection is performed by means of complementary techniques in different energy ranges and at different depths in the atmosphere, down to the Earth's surface.Monte Carlo codes are essential calculation tools which can describe the complexity of the physics of these phenomena, thus allowing the analysis of experimental data. However, these codes are affected by important uncertainties, concerning, in particular, hadronic physics at high energy. In this paper we shall report some results concerning inclusive particle fluxes and atmospheric shower properties as obtained using the FLUKA transport and interaction code. Some emphasis will also be given to the validation of the physics models of FLUKA involved in these calculations.

Battistoni, G.; Garzelli, M. V.; Muraro, S.; Sala, P. R. [University of Milano, Department of Physics, and INFN, Milan (Italy); Cerutti, F.; Ferrari, A.; Roesler, S. [CERN, Geneva (Switzerland); Fasso, A. [SLAC, Stanford, CA (United States); Lantz, M. [Chalmers University, Department of Fundamental Physics, Goteborg (Sweden); Pinsky, L. S. [University of Houston, Department of Physics, Houston, TX (United States); Ranft, J. [Siegen University, Fachbereich 7-Physik, Siegen (Germany)

2008-01-24

47

GCR flux reconstruction during the last three centuries validated by the Ti-44 in meteorites and Be-10 in ice  

NASA Astrophysics Data System (ADS)

In a previous work [1] we deduced that during prolonged minima of solar activity since 1700 the galactic cosmic rays (GCR) flux was much higher (˜2 times) respect to what we can infer from GCR modulation deduced solely by the Sunspot Number series. This flux was higher respect to what we observe in the last decades by Neutron Monitor or balloon and spacecraft-borne detectors and confirmed by the three fresh-fall meteorites that we have measured during solar cycle 22. Recently we have deduced the GCR annual mean spectra for the last 300 years [2], starting from the open solar magnetic flux proposed by Solanki et al. [3]. Utilizing the GCR flux we have calculated the 44Ti (T1/2 = 59.2 y) activity in meteorites taking into account the cross sections for its production from the main target element Fe and Ni. We compare the calculated activity with our measurements of the cosmogenic 44Ti in different chondrites fell in the period 1810-1997. The results are in close agreement both in phase and amplitude. The same procedure has been adopted for calculating the production rate of 10Be in atmosphere. Normalizing to the concentration in ice in the solar cycles 20 and 21 we obtain a good agreement with the 10Be profile in Dye3 core [4]. These results demonstrate that our inference of the GCR flux in the past 300 years is reliable. [1] Bonino G., Cini Castagnoli G., Bhandari N., Taricco C., textit {Science}, 270, 1648, 1995 [2] Bonino G., Cini Castagnoli G., Cane D., Taricco C. and Bhandari N., textit {Proc. XXVII Intern. Cosmic Ray Conf.} (Hamburg, 2001) 3769-3772. [3] Solanki S.K., Schüssler M. and Fligge M.,Nature, 408, 445, 2000 [4] Beer J. et al., private communication

Cini Castagnoli, G.; Cane, D.; Taricco, C.; Bhandari, N.

2003-04-01

48

Mutations in GCR3, a gene involved in the expression of glycolytic genes in Saccharomyces cerevisiae, suppress the temperature-sensitive growth of hpr1 mutants  

SciTech Connect

To study the functions of DNA topoisomerase I and Hpr1 protein, a suppressor mutant of the temperature-sensitive growth of an hpr1 top1-5{sup ts} double mutant was isolated. The isolated triple mutant showed cold-sensitive growth. By complementation of this phenotype, the suppressor gene was cloned. DNA sequencing showed it to be GCR3, a gene involved in the expression of glycol genes. Further analysis showed that gcr3 mutations also suppressed the temperature-sensitive growth of hpr1 single mutants. Experiments with gcr3 truncation mutants also suggested a genetic interaction between GCR3 and HPR1. The fact that top1 suppressed the growth defect of gcr3 suggested an interaction between those two genes also. Plasmid DNA isolated from gcr3 mutants was significantly more negatively supercoiled than normal, suggesting that Gcr3 protein, like topoisomerase I and Hpr1p, affects chromatin structure, perhaps during transcription. 43 refs., 2 figs., 6 tabs.

Uemura, Hiroshi; Jigami, Yoshifumi [National Institute of Bioscience and Human-Technology, Tsukuba, Ibaraki (Japan); Pandit, Sunil; Sternglanz, R. [State Univ. of New York, Stony Brook, NY (United States)

1996-04-01

49

GCR Transport in the Brain: Assessment of Self-Shielding, Columnar Damage, and Nuclear Reactions on Cell Inactivation Rates  

NASA Technical Reports Server (NTRS)

Radiation shield design is driven by the need to limit radiation risks while optimizing risk reduction with launch mass/expense penalties. Both limitation and optimization objectives require the development of accurate and complete means for evaluating the effectiveness of various shield materials and body-self shielding. For galactic cosmic rays (GCR), biophysical response models indicate that track structure effects lead to substantially different assessments of shielding effectiveness relative to assessments based on LET-dependent quality factors. Methods for assessing risk to the central nervous system (CNS) from heavy ions are poorly understood at this time. High-energy and charge (HZE) ion can produce tissue events resulting in damage to clusters of cells in a columnar fashion, especially for stopping heavy ions. Grahn (1973) and Todd (1986) have discussed a microlesion concept or model of stochastic tissue events in analyzing damage from HZE's. Some tissues, including the CNS, maybe sensitive to microlesion's or stochastic tissue events in a manner not illuminated by either conventional dosimetry or fluence-based risk factors. HZE ions may also produce important lateral damage to adjacent cells. Fluences of high-energy proton and alpha particles in the GCR are many times higher than HZE ions. Behind spacecraft and body self-shielding the ratio of protons, alpha particles, and neutrons to HZE ions increases several-fold from free-space values. Models of GCR damage behind shielding have placed large concern on the role of target fragments produced from tissue atoms. The self-shielding of the brain reduces the number of heavy ions reaching the interior regions by a large amount and the remaining light particle environment (protons, neutrons, deuterons. and alpha particles) may be the greatest concern. Tracks of high-energy proton produce nuclear reactions in tissue, which can deposit doses of more than 1 Gv within 5 - 10 cell layers. Information on rates of cell killing from GCR, including patterns of cell killing from single particle tracks. can provide useful information on expected differences between proton and HZE tracks and clinical experiences with photon irradiation. To model effects on cells in the brain, it is important that transport models accurately describe changes in the GCR due to interactions in the cranium and proximate tissues. We describe calculations of the attenuated GCR particle fluxes at three dose-points in the brain and associated patterns of cell killing using biophysical models. The effects of the brain self-shielding and bone-tissue interface of the skull in modulating the GCR environment are considered. For each brain dose-point, the mass distribution in the surrounding 4(pi) solid angle is characterized using the CAM model to trace 512 rays. The CAM model describes the self-shielding by converting the tissue distribution to mass-equivalent aluminum, and nominal values of spacecraft shielding is considered. Particle transport is performed with the proton, neutron, and heavy-ion transport code HZETRN with the nuclear fragmentation model QMSFRG. The distribution of cells killed along the path of individual GCR ions is modeled using in vitro cell inactivation data for cells with varying sensitivity. Monte Carlo simulations of arrays of inactivated cells are considered for protons and heavy ions and used to describe the absolute number of cell killing events of various magnitude in the brain from the GCR. Included are simulations of positions of inactivated cells from stopping heavy ions and nuclear stars produced by high-energy ions most importantly, protons and neutrons.

Shavers, M. R.; Atwell, W.; Cucinotta, F. A.; Badhwar, G. D. (Technical Monitor)

1999-01-01

50

Model Calculations with Excited Nuclear Fragmentations and Implications of Current GCR Spectra  

NASA Astrophysics Data System (ADS)

As a result of the fragmentation process in nuclei, energy from the excited states may also contribute to the radiation damage on the cell structure. Radiation induced damage to the human body from the excited states of oxygen and several other nuclei and its fragments are of a concern in the context of the measured abundance of the current galactic cosmic rays (GCR) environment. Nuclear Shell model based calculations of the Selective-Core (Saganti-Cucinotta) approach are being expanded for O-16 nuclei fragments into N-15 with a proton knockout and O-15 with a neutron knockout are very promising. In our on going expansions of these nuclear fragmentation model calculations and assessments, we present some of the prominent nuclei interactions from a total of 190 isotopes that were identified for the current model expansion based on the Quantum Multiple Scattering Fragmentation Model (QMSFRG) of Cucinotta. Radiation transport model calculations with the implementation of these energy level spectral characteristics are expected to enhance the understanding of radiation damage at the cellular level. Implications of these excited energy spectral calculations in the assessment of radiation damage to the human body may provide enhanced understanding of the space radiation risk assessment.

Saganti, Premkumar

51

Assessment and Requirements of Nuclear Reaction Databases for GCR Transport in the Atmosphere and Structures  

NASA Technical Reports Server (NTRS)

The transport properties of galactic cosmic rays (GCR) in the atmosphere, material structures, and human body (self-shielding) am of interest in risk assessment for supersonic and subsonic aircraft and for space travel in low-Earth orbit and on interplanetary missions. Nuclear reactions, such as knockout and fragmentation, present large modifications of particle type and energies of the galactic cosmic rays in penetrating materials. We make an assessment of the current nuclear reaction models and improvements in these model for developing required transport code data bases. A new fragmentation data base (QMSFRG) based on microscopic models is compared to the NUCFRG2 model and implications for shield assessment made using the HZETRN radiation transport code. For deep penetration problems, the build-up of light particles, such as nucleons, light clusters and mesons from nuclear reactions in conjunction with the absorption of the heavy ions, leads to the dominance of the charge Z = 0, 1, and 2 hadrons in the exposures at large penetration depths. Light particles are produced through nuclear or cluster knockout and in evaporation events with characteristically distinct spectra which play unique roles in the build-up of secondary radiation's in shielding. We describe models of light particle production in nucleon and heavy ion induced reactions and make an assessment of the importance of light particle multiplicity and spectral parameters in these exposures.

Cucinotta, F. A.; Wilson, J. W.; Shinn, J. L.; Tripathi, R. K.

1998-01-01

52

MHD compressor---expander conversion system integrated with GCR inside a deployable reflector  

SciTech Connect

This work originates from the proposal MHD Compressor-Expander Conversion System Integrated with a GCR Inside a Deployable Reflector''. The proposal concerned an innovative concept of nuclear, closed-cycle MHD converter for power generation on space-based systems in the multi-megawatt range. The basic element of this converter is the Power Conversion Unit (PCU) consisting of a gas core reactor directly coupled to an MHD expansion channel. Integrated with the PCU, a deployable reflector provides reactivity control. The working fluid could be either uranium hexafluoride or a mixture of uranium hexafluoride and helium, added to enhance the heat transfer properties. The original Statement of Work, which concerned the whole conversion system, was subsequently redirected and focused on the basic mechanisms of neutronics, reactivity control, ionization and electrical conductivity in the PCU. Furthermore, the study was required to be inherently generic such that the study was required to be inherently generic such that the analysis an results can be applied to various nuclear reactor and/or MHD channel designs''.

Tuninetti, G. (Ansaldo S.p.A., Genoa (Italy). Research Div.); Botta, E.; Criscuolo, C.; Riscossa, P. (Ansaldo S.p.A., Genoa (Italy). Nuclear Div.); Giammanco, F. (Pisa Univ. (Italy). Dipt. di Fisica); Rosa-Clot, M. (Florence Univ. (Italy). Dipt. di Fisica)

1989-04-20

53

Energy and Angular Distribution of GCR Secondary Particles from the Lunar Surface: CRaTER Observations and Geant4 Simulations  

NASA Astrophysics Data System (ADS)

In previous work we have simulated in detail the production of secondary particles from the impact of galactic cosmic rays (GCRs) on the lunar surface, and the response of the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) sensor aboard the Lunar Reconnaissance Orbiter (LRO) spacecraft to both primary and secondary particles. Because the imaging science done by most of the other LRO sensors requires that those sensors look straight down at the lunar surface, most CRaTER observations are made with the bidirectional coincidence channels of the sensor responding to cosmic rays coming nearly straight down and secondary particles coming nearly straight up from the lunar surface, and these are the observations with which we have compared our simulations to date. However, LRO does spend some time pointing away from its nominal zenith/nadir orientation. Our simulations show that the flux of secondary particles becomes more intense and reaches to higher energies for particles coming off the surface away from the vertical direction. We present here the first results from a comparison of simulations of these harder, more intense parts of the secondary-particle population with observations of these particles as the sensor points more toward the lunar limb. In addition, previous work included GCR species from hydrogen to nickel, but secondary particles only from GCR protons and alphas; in the present work we add secondaries from heavier GCR ions to the simulated population.

Looper, M. D.; Mazur, J. E.; Blake, B.; Spence, H. E.; Golightly, M. J.; Case, A. W.; Kasper, J. C.; Townsend, L. W.

2012-12-01

54

Determining the Magnitude of Neutron and Galactic Cosmic Ray (GCR) Fluxes at the Moon using the Lunar Exploration Neutron Detector during the Historic Space-Age Era of High GCR Flux  

NASA Astrophysics Data System (ADS)

The Lunar Reconnaissance Orbiter (LRO) was launched June 18, 2009 during an historic space-age era of minimum solar activity [1]. The lack of solar sunspot activity signaled a complex set of heliospheric phenomena [2,3,4] that also gave rise to a period of unprecedentedly high Galactic Cosmic Ray (GCR) flux [5]. These events coincided with the primary mission of the Lunar Exploration Neutron Detector (LEND, [6]), onboard LRO in a nominal 50-km circular orbit of the Moon [7]. Methods to calculate the emergent neutron albedo population using Monte Carlo techniques [8] rely on an estimate of the GCR flux and spectra calibrated at differing periods of solar activity [9,10,11]. Estimating the actual GCR flux at the Moon during the LEND's initial period of operation requires a correction using a model-dependent heliospheric transport modulation parameter [12] to adjust the GCR flux appropriate to this unique solar cycle. These corrections have inherent uncertainties depending on model details [13]. Precisely determining the absolute neutron and GCR fluxes is especially important in understanding the emergent lunar neutrons measured by LEND and subsequently in estimating the hydrogen/water content in the lunar regolith [6]. LEND is constructed with a set of neutron detectors to meet differing purposes [6]. Specifically there are two sets of detector systems that measure the flux of epithermal neutrons: a) the uncollimated Sensor for Epi-Thermal Neutrons (SETN) and b) the Collimated Sensor for Epi-Thermal Neutrons (CSETN). LEND SETN and CSETN observations form a complementary set of simultaneous measurements that determine the absolute scale of emergent lunar neutron flux in an unambiguous fashion and without the need for correcting to differing solar-cycle conditions. LEND measurements are combined with a detailed understanding of the sources of instrumental back-ground, and the performance of CSETN and SETN. This comparison allows us to calculate a constant scale factor that determines the absolute flux of neutrons at the Moon and then subsequently to deduce the proper scale of the GCR flux. References: [1] H. S. Ahluwakia and R. C. Ygbuhay (2010) Twelfth International Solar Wind Conference, 699-702. [2] F. B. McDonald et al. (2010) JRL, 37, L18101. [3] H. Moraal and P. H. Stoker (2010) JGR, 115, 12109-12118. [4] R. Kataoka et al. (2012) Space Weather, 10, 11001-11007. [4] C-L. Huang et al. (2009), JRL, 37, L09109-L09104. [5] R. A. Mewaldt et al. (2010) Ap. J Lett., 723, L1-L6. [6] I. G. Mitrofanov et al. (2010) Space Science Rev., 150, 283-207. [7] C. R. Tooley et al. (2010) Space Science Rev., 150, 23-62. [8] G. W. McKinney et al. (2006) JGR, 111, 6004-6018. [9] P. M. O'Neil (2010) IEEE Trans. Nucl. Sci., 57(6), 3148-3153. [10] American National Standards Institute Tech. Rep. ISO 15390 (2004). [11] I. G. Usokin et al. (2008) JGR, 110, A12108. [12] M. D. Looper et al. (2013) Space Weather, 11, 142-152. [13] A. I. Mrigakshi et al. (2012) JGR, 117, A08109-A08121.

Chin, G.; Sagdeev, R.; Boynton, W. V.; Mitrofanov, I. G.; Milikh, G. M.; Su, J. J.; Livengood, T. A.; McClanahan, T. P.; Evans, L.; Starr, R. D.; litvak, M. L.; Sanin, A.

2013-12-01

55

Event-based internet biosurveillance: relation to epidemiological observation  

PubMed Central

Background The World Health Organization (WHO) collects and publishes surveillance data and statistics for select diseases, but traditional methods of gathering such data are time and labor intensive. Event-based biosurveillance, which utilizes a variety of Internet sources, complements traditional surveillance. In this study we assess the reliability of Internet biosurveillance and evaluate disease-specific alert criteria against epidemiological data. Methods We reviewed and compared WHO epidemiological data and Argus biosurveillance system data for pandemic (H1N1) 2009 (April 2009 – January 2010) from 8 regions and 122 countries to: identify reliable alert criteria among 15 Argus-defined categories; determine the degree of data correlation for disease progression; and assess timeliness of Internet information. Results Argus generated a total of 1,580 unique alerts; 5 alert categories generated statistically significant (p?

2012-01-01

56

DNA binding of the cell cycle transcriptional regulator GcrA depends on N6-adenosine methylation in Caulobacter crescentus and other Alphaproteobacteria.  

PubMed

Several regulators are involved in the control of cell cycle progression in the bacterial model system Caulobacter crescentus, which divides asymmetrically into a vegetative G1-phase (swarmer) cell and a replicative S-phase (stalked) cell. Here we report a novel functional interaction between the enigmatic cell cycle regulator GcrA and the N6-adenosine methyltransferase CcrM, both highly conserved proteins among Alphaproteobacteria, that are activated early and at the end of S-phase, respectively. As no direct biochemical and regulatory relationship between GcrA and CcrM were known, we used a combination of ChIP (chromatin-immunoprecipitation), biochemical and biophysical experimentation, and genetics to show that GcrA is a dimeric DNA-binding protein that preferentially targets promoters harbouring CcrM methylation sites. After tracing CcrM-dependent N6-methyl-adenosine promoter marks at a genome-wide scale, we show that these marks recruit GcrA in vitro and in vivo. Moreover, we found that, in the presence of a methylated target, GcrA recruits the RNA polymerase to the promoter, consistent with its role in transcriptional activation. Since methylation-dependent DNA binding is also observed with GcrA orthologs from other Alphaproteobacteria, we conclude that GcrA is the founding member of a new and conserved class of transcriptional regulators that function as molecular effectors of a methylation-dependent (non-heritable) epigenetic switch that regulates gene expression during the cell cycle. PMID:23737758

Fioravanti, Antonella; Fumeaux, Coralie; Mohapatra, Saswat S; Bompard, Coralie; Brilli, Matteo; Frandi, Antonio; Castric, Vincent; Villeret, Vincent; Viollier, Patrick H; Biondi, Emanuele G

2013-05-01

57

DNA Binding of the Cell Cycle Transcriptional Regulator GcrA Depends on N6-Adenosine Methylation in Caulobacter crescentus and Other Alphaproteobacteria  

PubMed Central

Several regulators are involved in the control of cell cycle progression in the bacterial model system Caulobacter crescentus, which divides asymmetrically into a vegetative G1-phase (swarmer) cell and a replicative S-phase (stalked) cell. Here we report a novel functional interaction between the enigmatic cell cycle regulator GcrA and the N6-adenosine methyltransferase CcrM, both highly conserved proteins among Alphaproteobacteria, that are activated early and at the end of S-phase, respectively. As no direct biochemical and regulatory relationship between GcrA and CcrM were known, we used a combination of ChIP (chromatin-immunoprecipitation), biochemical and biophysical experimentation, and genetics to show that GcrA is a dimeric DNA–binding protein that preferentially targets promoters harbouring CcrM methylation sites. After tracing CcrM-dependent N6-methyl-adenosine promoter marks at a genome-wide scale, we show that these marks recruit GcrA in vitro and in vivo. Moreover, we found that, in the presence of a methylated target, GcrA recruits the RNA polymerase to the promoter, consistent with its role in transcriptional activation. Since methylation-dependent DNA binding is also observed with GcrA orthologs from other Alphaproteobacteria, we conclude that GcrA is the founding member of a new and conserved class of transcriptional regulators that function as molecular effectors of a methylation-dependent (non-heritable) epigenetic switch that regulates gene expression during the cell cycle.

Mohapatra, Saswat S.; Bompard, Coralie; Brilli, Matteo; Frandi, Antonio; Castric, Vincent; Villeret, Vincent; Viollier, Patrick H.; Biondi, Emanuele G.

2013-01-01

58

Importance effects on performance in event?based prospective memory tasks  

Microsoft Academic Search

In the present study we manipulated the importance of performing two event?based prospective memory tasks. In Experiment 1, the event?based task was assumed to rely on relatively automatic processes, whereas in Experiment 2 the event?based task was assumed to rely on a more demanding monitoring process. In contrast to the first experiment, the second experiment showed that importance had a

Matthias Kliegel; Mike Martin; Mark McDaniel; Gilles Einstein

2004-01-01

59

Differential Regulation of the Overlapping Kaposi's Sarcoma-Associated Herpesvirus vGCR (orf74) and LANA (orf73) Promoters  

PubMed Central

Similar to that of other herpesviruses, Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) lytic replication destroys the host cell, while the virus can persist in a latent state in synchrony with the host. During latency only a few genes are transcribed, and the question becomes one of what determines latent versus lytic gene expression. Here we undertake a detailed analysis of the latency-associated nuclear antigen (LANA [orf73]) promoter (LANAp). We characterized a minimal region that is necessary and sufficient to maintain high-level transcription in all tissues tested, including primary endothelial cells and B cells, which are the suspected natural host for KSHV. We show that in transient-transfection assays LANAp mimics the expression pattern observed for the authentic promoter in the context of the KSHV episome. Unlike other KSHV promoters tested thus far, LANAp is not affected by tetradecanoyl phorbol acetate or viral lytic cycle functions. It is, however, subject to control by LANA itself and cellular regulatory factors, such as p53. This is in contrast to the K14/vGCR (orf74) promoter, which overlaps LANAp and directs transcription on the opposite strand. We isolated a minimal cis-regulatory region sufficient for K14/vGCR promoter activity and show that it, too, mimics the regulation observed for the authentic viral promoter. In particular, we demonstrate that its activity is absolutely dependent on the immediate-early transactivator orf50, the KSHV homolog of the Epstein-Barr virus Rta transactivator.

Jeong, Joseph; Papin, James; Dittmer, Dirk

2001-01-01

60

Differential expression of the HHV-8 vGCR cellular homolog gene in AIDS-associated and classic Kaposi's sarcoma: potential role of HIV-1 Tat.  

PubMed

Human herpesvirus 8 (HHV-8) has been causally linked to Kaposi's sarcoma (KS). There is significant homology between some HHV-8 genes and cellular genes including D-type cyclin (vCYC), G protein coupled receptor (vGCR), macrophage inflammatory proteins (vMIP-I, vMIP-II), bcl-2 (vBCL2), interferon regulatory factor-1 (vIRF1), interleukin-6 (vIL6), and complement-binding protein (vCBP). In this study, we analyzed expression of these viral homologs and HIV-1 Tat by reverse-transcriptase polymerase chain reaction (RT-PCR) coupled with Southern blot hybridization in AIDS-KS (AKS) tissue, classic KS tissue(CKS), and peripheral blood mononuclear cells, and phorbol ester (TPA)-treated and untreated HHV-8 positive lymphoma cells (BCBL1). While vCYC (AKS 6 of 6; CKS 3 of 3), vMIP-I (AKS 5 of 6, CKS 3 of 3), vBCL2 (AKS 6 of 6; CKS 3 of 3), and vIRF1 (AKS 5 of 6, CKS 3 of 3) transcripts were detected in both AKS and CKS, vGCR and HIV-1 Tat were expressed only in AKS samples (vGCR: AKS 3 of 6, CKS 0 of 3; Tat: AKS 4 of 6, CKS 0 of 3). vMIPII, vCBP, and vIL6 expression were not detected in any KS samples. Since vGCR expression is limited to AKS, it is possible that vGCR is activated by HIV-1 Tat. These results suggest that HIV-1 Tat may contribute to AKS pathogenesis through the tumorigenic and angiogenic effects of vGCR. PMID:10662620

Yen-Moore, A; Hudnall, S D; Rady, P L; Wagner, R F; Moore, T O; Memar, O; Hughes, T K; Tyring, S K

2000-02-15

61

Asteroid! An Event-Based Science Module. Teacher's Guide. Astronomy Module.  

ERIC Educational Resources Information Center

This book is designed for middle school earth science or general science teachers to help their students learn scientific literacy through event-based science. Unlike traditional curricula, the event- based earth science module is a student-centered, interdisciplinary, inquiry-oriented program that emphasizes cooperative learning, teamwork,…

Wright, Russell G.

62

Asteroid! An Event-Based Science Module. Student Edition. Astronomy Module.  

ERIC Educational Resources Information Center

This book is designed for middle school students to learn scientific literacy through event-based science. Unlike traditional curricula, the event-based earth science module is a student-centered, interdisciplinary, inquiry-oriented program that emphasizes cooperative learning, teamwork, independent research, hands-on investigations, and…

Wright, Russell G.

63

Issues in Testing Dependable Event-Based Systems at a Systems Integration Company  

Microsoft Academic Search

Testing of dependable event-based systems is very important to ensure that all requirements (including nonfunctional requirements such as reliability, availability, safety and security) are met and the relevant standards are considered. Siemens Program and Systems Engineering is a company that builds dependable event-based systems in multiple domains. A special unit at PSE, the Support Center Test, focuses on testing issues.

Armin Beer; Matthias Heindl

2007-01-01

64

Oil Spill!: An Event-Based Science Module. Teacher's Guide. Oceanography Module.  

ERIC Educational Resources Information Center

This book is designed for middle school earth science or general science teachers to help their students learn scientific literacy through event-based science. Unlike traditional curricula, the event- based earth science module is a student-centered, interdisciplinary, inquiry-oriented program that emphasizes cooperative learning, teamwork,…

Wright, Russell G.

65

Gold Rush!: An Event-Based Science Module. Student Edition. Rocks and Minerals Module.  

ERIC Educational Resources Information Center

This book is designed for middle school students to learn scientific literacy through event-based science. Unlike traditional curricula, the event-based earth science module is a student-centered, interdisciplinary, inquiry-oriented program that emphasizes cooperative learning, teamwork, independent research, hands-on investigations, and…

Wright, Russell G.

66

Fire!: An Event-Based Science Module. Teacher's Guide. Chemistry and Fire Ecology Module.  

ERIC Educational Resources Information Center

This book is designed for middle school earth science or physical science teachers to help their students learn scientific literacy through event-based science. Unlike traditional curricula, the event- based earth science module is a student-centered, interdisciplinary, inquiry-oriented program that emphasizes cooperative learning, teamwork,…

Wright, Russell G.

67

The dynamics of intention retrieval and coordination of action in event-based prospective memory  

Microsoft Academic Search

Event-based prospective memory requires responding to cues in the environment that are associated with a previously established intention. Some researchers believe that intentions reside in memory with an above baseline level of activation, a phenomenon called the intention superiority effect. The authors of this study predicted that intention superiority would be masked by additional cognitive processes associated with successful event-based

Richard L. Marsh; Jason L. Hicks; Valerie Watson

2002-01-01

68

The Source of Adult Age Differences in Event-Based Prospective Memory: A Multinomial Modeling Approach  

ERIC Educational Resources Information Center

Event-based prospective memory involves remembering to perform an action in response to a particular future event. Normal younger and older adults performed event-based prospective memory tasks in 2 experiments. The authors applied a formal multinomial processing tree model of prospective memory (Smith & Bayen, 2004) to disentangle age differences…

Smith, Rebekah E.; Bayen, Ute J.

2006-01-01

69

Draft Title 40 CFR 191 compliance certification application for the Waste Isolation Pilot Plant. Volume 6: Appendix GCR Volume 1  

SciTech Connect

The Geological Characterization Report (GCR) for the WIPP site presents, in one document, a compilation of geologic information available to August, 1978, which is judged to be relevant to studies for the WIPP. The Geological Characterization Report for the WIPP site is neither a preliminary safety analysis report nor an environmental impact statement; these documents, when prepared, should be consulted for appropriate discussion of safety analysis and environmental impact. The Geological Characterization Report of the WIPP site is a unique document and at this time is not required by regulatory process. An overview is presented of the purpose of the WIPP, the purpose of the Geological Characterization Report, the site selection criteria, the events leading to studies in New Mexico, status of studies, and the techniques employed during geological characterization.

NONE

1995-03-31

70

The GCR1 and GPA1 participate in promotion of Arabidopsis primary root elongation induced by N-acyl-homoserine lactones, the bacterial quorum-sensing signals.  

PubMed

Many gram-negative bacteria use N-acyl-homoserine lactones (AHL) as quorum-sensing signals to coordinate their collective behaviors. Accumulating evidence indicates that plants can respond to AHL. However, little is known about the molecular mechanism of plants reacting to these bacterial signals. In this study, we show that the treatment of Arabidopsis roots with N-3-oxo-hexanoyl-homoserine lactone (3OC6-HSL) and N-3-oxo-octanoyl-homoserine lactone (3OC8-HSL) resulted in significant root elongation. The genetic analysis revealed that the T-DNA insertional mutants of gcr1, encoding a G-protein-coupled receptor GCR1, were insensitive to 3OC6-HSL or 3OC8-HSL in assays of root growth. The loss-of-function mutants of the sole canonical G? subunit GPA1 showed no response to AHL promotion of root elongation whereas G? gain-of-function plants overexpressing either the wild type or a constitutively active version of Arabidopsis G? exhibited the exaggerated effect on root elongation caused by AHL. Furthermore, the expression of GCR1 and GPA1 were significantly upregulated after plants were contacted with both AHL. Taken together, our results suggest that GCR1 and GPA1 are involved in AHL-mediated elongation of Arabidopsis roots. This provides insight into the mechanism of plant responses to bacterial quorum-sensing signals. PMID:22250582

Liu, Fang; Bian, Ziriu; Jia, Zhenhua; Zhao, Qian; Song, Shuishan

2012-05-01

71

Differential regulation of the overlapping Kaposi's sarcoma-associated herpesvirus vGCR (orf74) and LANA (orf73) promoters.  

PubMed

Similar to that of other herpesviruses, Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) lytic replication destroys the host cell, while the virus can persist in a latent state in synchrony with the host. During latency only a few genes are transcribed, and the question becomes one of what determines latent versus lytic gene expression. Here we undertake a detailed analysis of the latency-associated nuclear antigen (LANA [orf73]) promoter (LANAp). We characterized a minimal region that is necessary and sufficient to maintain high-level transcription in all tissues tested, including primary endothelial cells and B cells, which are the suspected natural host for KSHV. We show that in transient-transfection assays LANAp mimics the expression pattern observed for the authentic promoter in the context of the KSHV episome. Unlike other KSHV promoters tested thus far, LANAp is not affected by tetradecanoyl phorbol acetate or viral lytic cycle functions. It is, however, subject to control by LANA itself and cellular regulatory factors, such as p53. This is in contrast to the K14/vGCR (orf74) promoter, which overlaps LANAp and directs transcription on the opposite strand. We isolated a minimal cis-regulatory region sufficient for K14/vGCR promoter activity and show that it, too, mimics the regulation observed for the authentic viral promoter. In particular, we demonstrate that its activity is absolutely dependent on the immediate-early transactivator orf50, the KSHV homolog of the Epstein-Barr virus Rta transactivator. PMID:11160678

Jeong, J; Papin, J; Dittmer, D

2001-02-01

72

A contextual inquiry of expert programmers in an event-based programming environment  

Microsoft Academic Search

Event-based programming has been studied little, yet recent work suggests that language paradigm can predict programming strategies and performance. A contextual inquiry of four expert programmers using the Alice 3D programming environment was performed in order to discover how event-based programming strategies might be supported in programming environments. Various programming, testing, and debugging breakdowns were extracted from observations and possible

Andrew Jensen Ko

2003-01-01

73

Putting events in context: aspects for event-based distributed programming  

Microsoft Academic Search

Event-based programming is an appealing paradigm for developing pervasive systems since events enable the decoupling of interacting components. Unfortunately, many event-based languages and systems have hardwired notions of physical or logical time and space. This limits their adaptability and target deployment environments, as pervasive systems rely on inherent interaction and interchanging of different protocols and infrastructures. This paper introduces domain-specific

Adrian Holzer; Lukasz Ziarek; K. R. Jayaram; Patrick Eugster

2011-01-01

74

ALLUVSIM: A program for event-based stochastic modeling of fluvial depositional systems  

Microsoft Academic Search

This paper presents an algorithm for the construction of event-based fluvial models. The event-based approach may be applied to construct stochastic pseudo-process-based fluvial models for a variety of fluvial styles with conditioning to sparse well data (1–5 wells) and areal and vertical trends. The initial models are generated by placing large-scale features, such as channels and crevasse splays, into the

M. J. Pyrcz; J. B. Boisvert; C. V. Deutsch

2009-01-01

75

Are Time- and Event-based Prospective Memory Comparably Affected in HIV Infection?†  

PubMed Central

According to the multi-process theory of prospective memory (ProM), time-based tasks rely more heavily on strategic processes dependent on prefrontal systems than do event-based tasks. Given the prominent frontostriatal pathophysiology of HIV infection, one would expect HIV-infected individuals to demonstrate greater deficits in time-based versus event-based ProM. However, the two prior studies examining this question have produced variable results. We evaluated this hypothesis in 143 individuals with HIV infection and 43 demographically similar seronegative adults (HIV?) who completed the research version of the Memory for Intentions Screening Test, which yields parallel subscales of time- and event-based ProM. Results showed main effects of HIV serostatus and cue type, but no interaction between serostatus and cue. Planned pair-wise comparisons showed a significant effect of HIV on time-based ProM and a trend-level effect on event-based ProM that was driven primarily by the subset of participants with HIV-associated neurocognitive disorders. Nevertheless, time-based ProM was more strongly correlated with measures of executive functions, attention/working memory, and verbal fluency in HIV-infected persons. Although HIV-associated deficits in time- and event-based ProM appear to be of comparable severity, the cognitive architecture of time-based ProM may be more strongly influenced by strategic monitoring and retrieval processes.

Zogg, Jennifer B.; Woods, Steven Paul; Weber, Erica; Doyle, Katie; Grant, Igor; Atkinson, J. Hampton; Ellis, Ronald J.; McCutchan, J. Allen; Marcotte, Thomas D.; Hale, Braden R.; Ellis, Ronald J.; McCutchan, J. Allen; Letendre, Scott; Capparelli, Edmund; Schrier, Rachel; Heaton, Robert K.; Cherner, Mariana; Moore, David J.; Jernigan, Terry; Fennema-Notestine, Christine; Archibald, Sarah L.; Hesselink, John; Annese, Jacopo; Taylor, Michael J.; Masliah, Eliezer; Everall, Ian; Langford, T. Dianne; Richman, Douglas; Smith, David M.; McCutchan, J. Allen; Everall, Ian; Lipton, Stuart; McCutchan, J. Allen; Atkinson, J. Hampton; Ellis, Ronald J.; Letendre, Scott; Atkinson, J. Hampton; von Jaeger, Rodney; Gamst, Anthony C.; Cushman, Clint; Masys, Daniel R.; Abramson, Ian; Ake, Christopher; Vaida, Florin

2011-01-01

76

An Event-Based Approach to Distributed Diagnosis of Continuous Systems  

NASA Technical Reports Server (NTRS)

Distributed fault diagnosis solutions are becoming necessary due to the complexity of modern engineering systems, and the advent of smart sensors and computing elements. This paper presents a novel event-based approach for distributed diagnosis of abrupt parametric faults in continuous systems, based on a qualitative abstraction of measurement deviations from the nominal behavior. We systematically derive dynamic fault signatures expressed as event-based fault models. We develop a distributed diagnoser design algorithm that uses these models for designing local event-based diagnosers based on global diagnosability analysis. The local diagnosers each generate globally correct diagnosis results locally, without a centralized coordinator, and by communicating a minimal number of measurements between themselves. The proposed approach is applied to a multi-tank system, and results demonstrate a marked improvement in scalability compared to a centralized approach.

Daigle, Matthew; Roychoudhurry, Indranil; Biswas, Gautam; Koutsoukos, Xenofon

2010-01-01

77

Event-based intelligent control system of carbide electric arc furnace (CEAF)  

Microsoft Academic Search

The electric arc furnace has been widely used in steel-making and carbide production. In the paper, the analysis of the construction of the CEAF and the procedure of the carbide production is considered first, then the design methodology of an event-based intelligent control system is presented for the electrode positioning control of the CEAF. With the output we make an

Q. P. Wang; D. L. Tarn; Y. C. Wang

2000-01-01

78

The Cost of Event-Based Prospective Memory: Salient Target Events  

ERIC Educational Resources Information Center

Evidence has begun to accumulate showing that successful performance of event-based prospective memory (PM) comes at a cost to other ongoing activities. The current study builds on previous work by examining the cost associated with PM when the target event is salient. Target salience is among the criteria for automatic retrieval of intentions…

Smith, Rebekah E.; Hunt, R. Reed; McVay, Jennifer C.; McConnell, Melissa D.

2007-01-01

79

Exploiting an event-based infrastructure to develop complex distributed systems  

Microsoft Academic Search

The development of complex distributed systems demands for the creation of suitable architectural styles (or paradigms) and related run-time infrastructures. An emerging style that is receiving increasing attention is based o n the notion of event. In an event-based architecture, distributed software components interact by generating and consuming events. The occurrence of an event in a component (called source) is

Gianpaolo Cugola; Elisabetta Di Nitto; Alfonso Fuggetta

1998-01-01

80

An Event-Based Acoustic-Phonetic Approach For Speech Segmentation And E-Set Recognition  

Microsoft Academic Search

In this paper, we discuss an automatic event-based recognition system (EBS) that is based on phonetic feature theory and acoustic phonetics. First, acoustic events related to the manner phonetic features are extracted from the speech signal. Second, based on the manner acoustic events, information related to the place phonetic features and voicing are extracted. Most recently, we focused on place

Amit Juneja; Carol Espy-Wilson

2003-01-01

81

An Observation on the Spontaneous Noticing of Prospective Memory Event-Based Cues  

ERIC Educational Resources Information Center

In event-based prospective memory, current theories make differing predictions as to whether intention-related material can be spontaneously noticed (i.e., noticed without relying on preparatory attentional processes). In 2 experiments, participants formed an intention that was contextually associated to the final phase of the experiment, and…

Knight, Justin B.; Meeks, J. Thadeus; Marsh, Richard L.; Cook, Gabriel I.; Brewer, Gene A.; Hicks, Jason L.

2011-01-01

82

The Cost of Event-Based Prospective Memory: Salient Target Events  

Microsoft Academic Search

Evidence has begun to accumulate showing that successful performance of event-based prospective memory (PM) comes at a cost to other ongoing activities. The current study builds on previous work by examining the cost associated with PM when the target event is salient. Target salience is among the criteria for automatic retrieval of intentions according to the multiprocess view of PM.

Rebekah E. Smith; R. Reed Hunt; Jennifer C. McVay; Melissa D. McConnell

2007-01-01

83

Neural Correlates of Attentional and Mnemonic Processing in Event-Based Prospective Memory  

PubMed Central

Prospective memory (PM), or memory for realizing delayed intentions, was examined with an event-based paradigm while simultaneously measuring neural activity with high-density EEG recordings. Specifically, the neural substrates of monitoring for an event-based cue were examined, as well as those perhaps associated with the cognitive processes supporting detection of cues and fulfillment of intentions. Participants engaged in a baseline lexical decision task (LDT), followed by a LDT with an embedded PM component. Event-based cues were constituted by color and lexicality (red words). Behavioral data provided evidence that monitoring, or preparatory attentional processes, were used to detect cues. Analysis of the event-related potentials (ERP) revealed visual attentional modulations at 140 and 220?ms post-stimulus associated with preparatory attentional processes. In addition, ERP components at 220, 350, and 400?ms post-stimulus were enhanced for intention-related items. Our results suggest preparatory attention may operate by selectively modulating processing of features related to a previously formed event-based intention, as well as provide further evidence for the proposal that dissociable component processes support the fulfillment of delayed intentions.

Knight, Justin B.; Ethridge, Lauren E.; Marsh, Richard L.; Clementz, Brett A.

2009-01-01

84

Electrophysiological Correlates of Strategic Monitoring in Event-Based and Time-Based Prospective Memory  

PubMed Central

Prospective memory (PM) is the ability to remember to accomplish an action when a particular event occurs (i.e., event-based PM), or at a specific time (i.e., time-based PM) while performing an ongoing activity. Strategic Monitoring is one of the basic cognitive functions supporting PM tasks, and involves two mechanisms: a retrieval mode, which consists of maintaining active the intention in memory; and target checking, engaged for verifying the presence of the PM cue in the environment. The present study is aimed at providing the first evidence of event-related potentials (ERPs) associated with time-based PM, and at examining differences and commonalities in the ERPs related to Strategic Monitoring mechanisms between event- and time-based PM tasks. The addition of an event-based or a time-based PM task to an ongoing activity led to a similar sustained positive modulation of the ERPs in the ongoing trials, mainly expressed over prefrontal and frontal regions. This modulation might index the retrieval mode mechanism, similarly engaged in the two PM tasks. On the other hand, two further ERP modulations were shown specifically in an event-based PM task. An increased positivity was shown at 400–600 ms post-stimulus over occipital and parietal regions, and might be related to target checking. Moreover, an early modulation at 130–180 ms post-stimulus seems to reflect the recruitment of attentional resources for being ready to respond to the event-based PM cue. This latter modulation suggests the existence of a third mechanism specific for the event-based PM; that is, the “readiness mode”.

Cona, Giorgia; Arcara, Giorgio; Tarantino, Vincenza; Bisiacchi, Patrizia Silvia

2012-01-01

85

Use of Unstructured Event-Based Reports for Global Infectious Disease Surveillance  

PubMed Central

Free or low-cost sources of unstructured information, such as Internet news and online discussion sites, provide detailed local and near real-time data on disease outbreaks, even in countries that lack traditional public health surveillance. To improve public health surveillance and, ultimately, interventions, we examined 3 primary systems that process event-based outbreak information: Global Public Health Intelligence Network, HealthMap, and EpiSPIDER. Despite similarities among them, these systems are highly complementary because they monitor different data types, rely on varying levels of automation and human analysis, and distribute distinct information. Future development should focus on linking these systems more closely to public health practitioners in the field and establishing collaborative networks for alert verification and dissemination. Such development would further establish event-based monitoring as an invaluable public health resource that provides critical context and an alternative to traditional indicator-based outbreak reporting.

Blench, Michael; Tolentino, Herman; Freifeld, Clark C.; Mandl, Kenneth D.; Mawudeku, Abla; Eysenbach, Gunther; Brownstein, John S.

2009-01-01

86

Extending the Event-Based Programming Model to support Sensor-Driven Ubiquitous Computing Applications  

Microsoft Academic Search

We propose an extension to the event-based programming model for sensor-driven ubiquitous computing applications. The extension consists of three abstractions: Multi-event handlers, event streams and execution policies. We believe that these additional abstractions simplify the task of writing applications in this domain. In this position paper we present the ex-tensions and demonstrate our prototype middleware implemented in C.

Sean Reilly; Mads Haahr

2009-01-01

87

Event-based simulation of fringe tracking in an optical interferometer  

NASA Astrophysics Data System (ADS)

We present the architecture of a software package for simulating an interferometer system. The different components of the interferometer operate in parallel with each other and communicate on regular or semi-regular time-scales. It is important to get this simultaneity correct while simulating the system on a sequential computer. The following paper describes a event-based simulation architecture which makes this possible.

Jorgensen, Anders M.

2008-07-01

88

A new approach in object-oriented methodology for creating event-based simulator  

Microsoft Academic Search

This paper explores software design methodologies in the context of creating a simulator and proposes a methodology to design and implement an event-based simulator namely SimMet. SimMet is explored in the context of the development of a complex simulator for simulating real world conditions to use in science, technology and medicine and other simulations. In this paper we interested in

Saeed Aliakbarian; Ahmad Abdollahzadeh; Leila Jalali

2006-01-01

89

State\\/Event-Based LTL Model Checking under Parametric Generalized Fairness  

Microsoft Academic Search

\\u000a In modeling a concurrent system, fairness constraints are usually considered at a specific granularity level of the system,\\u000a leading to many different variants of fairness: transition fairness, object\\/process fairness, actor fairness, etc. These different\\u000a notions of fairness can be unified by making explicit their parametrization over the relevant entities in the system as universal quantification. We propose a state\\/event-based framework

Kyungmin Bae; José Meseguer

90

Event-based prospective memory and executive control of working memory  

Microsoft Academic Search

In 5 experiments, the character of concurrent cognitive processing was manipulated during an event-based prospective memory task. High- and low-load conditions that differed only in the difficulty of the concurrent task were tested in each experiment. In Experiments 1 and 2, attention-demanding tasks from the literature on executive control produced decrements in prospective memory. In Experiment 3, attention was divided

Richard L. Marsh; Jason L. Hicks

1998-01-01

91

Deriving Tabular Event-Based Specifications from Goal-Oriented Requirements Models  

Microsoft Academic Search

Goal-oriented methods are increasingly popular for elaborating software requirements. They provide systematic support for incrementally building intentional, structural and operational models of the software and its environment together with various techniques for early analysis, e.g., to manage conflicting goals or anticipate abnormal environment behaviors that prevent goals from being achieved. On the other hand, tabular event-based methods are well-established for

Renaud De Landtsheer; Emmanuel Letier; Axel Van Lamsweerde

2003-01-01

92

Differential Expression of the HHV-8 vGCR Cellular Homolog Gene in AIDS-Associated and Classic Kaposi's Sarcoma: Potential Role of HIV1 Tat  

Microsoft Academic Search

Human herpesvirus 8 (HHV-8) has been causally linked to Kaposi's sarcoma (KS). There is significant homology between some HHV-8 genes and cellular genes including D-type cyclin (vCYC), G protein coupled receptor (vGCR), macrophage inflammatory proteins (vMIP-I, vMIP-II), bcl-2 (vBCL2), interferon regulatory factor-1 (vIRF1), interleukin-6 (vIL6), and complement-binding protein (vCBP). In this study, we analyzed expression of these viral homologs and

Angela Yen-Moore; S. David Hudnall; Peter L. Rady; Richard F. Wagner; Todd O. Moore; Omeed Memar; Thomas K. Hughes; Stephen K. Tyring

2000-01-01

93

Measuring pesticides in surface waters - continuous versus event-based sampling design  

NASA Astrophysics Data System (ADS)

Monitoring pesticides in surface waters is still a work- and cost-intensive procedure. Therefore, studies are normally carried out with a low monitoring frequency or with only a small selection of substances to be analyzed. In this case, it is not possible to picture the high temporal variability of pesticide concentrations, depending on application dates, weather conditions, cropping seasons and other factors. In 2007 the Institute of Landscape Ecology and Resource Management at Giessen University implemented a monitoring program during two pesticide application periods aiming to produce a detailed dataset of pesticide concentration for a wide range of substances, and which would also be suitable for the evaluation of catchment-scale pesticide exposure models. The Weida catchment in Thuringia (Eastern Germany) was selected as study area due to the availability of detailed pesticide application data for this region. The samples were taken from the river Weida at the gauge Zeulenroda, where it flows into a drinking water reservoir. The catchment area is 102 km². 67% of the area are in agricultural use, the main crops being winter wheat, maize, winter barley and winter rape. Dominant soil texture classes are loamy sand and loamy silt. About one third of the agricultural area is drained. The sampling was carried out in cooperation with the water supply agency of Thuringia (Fernwasserversorgung Thueringen). The sample analysis was done by the Institute of Environmental Research at Dortmund University. Two sampling schemes were carried out using two automatic samplers: continuous sampling with composite samples bottled two times per week and event-based sampling triggered by a discharge threshold. 53 samples from continuous sampling were collected. 19 discharge events were sampled with 45 individual samples (one to six per event). 34 pesticides and two metabolites were analyzed. 21 compounds were detected, nine of which having concentrations above the drinking water limit (0.1 µg/l). Pesticide loads were calculated separately from continuous and event-based samples. Only three pesticides dominated the total load. These were the herbicides metazachlor, terbuthylazine and quinmerac amounting to 75 % of the total load. This result seems to be plausible considering the fact that these three substances are the pesticides with the highest applied amounts in the Weida catchment. The highest pesticide loads of single pesticides were observed during or shortly after their application period, mostly accompanied by larger discharge events. They can be explained as surface runoff and drainage inputs from treated fields, since spray-drift inputs would be detected during the application periods without dependency on discharge events, and inputs from point-sources are usually independent of discharge as well. Annual loads calculated from continuous samples were mainly higher than those of event-based samples due to the fact that they represent a much longer time period. On the other hand, the highest concentrations were found in the event-based samples; in many cases they double the maximum concentrations of continuous samples. The monitoring study presented shows that different sampling strategies lead to different results and can answer different questions. If the intention is to detect maximum concentrations caused by surface runoff or drainage inputs, e.g. to assess the resulting risk to the aquatic community, the event based sampling method can be recommended. If one is rather interested in calculating annual pesticide loads and assessing which fractions of applied amounts finally enter the surface water network, continuous sampling is advisable. The dataset of continuous and event-based pesticide concentrations offers the possibility to evaluate and improve pesticide exposure models at the catchment scale. Further work is scheduled on this issue.

Eyring, J.; Bach, M.; Frede, H.-G.

2009-04-01

94

A Differential Deficit in Time- versus Event-based Prospective Memory in Parkinson's Disease  

PubMed Central

Objective The aim of the current study was to clarify the nature and extent of impairment in time- versus event-based prospective memory in Parkinson's disease (PD). Prospective memory is thought to involve cognitive processes that are mediated by prefrontal systems and are executive in nature. Given that individuals with PD frequently show executive dysfunction, it is important to determine whether these individuals may have deficits in prospective memory that could impact daily functions, such as taking medications. Although it has been reported that individuals with PD evidence impairment in prospective memory, it is still unclear whether they show a greater deficit for time- versus event-based cues. Method Fifty-four individuals with PD and 34 demographically similar healthy adults were administered a standardized measure of prospective memory that allows for a direct comparison of time-based and event-based cues. In addition, participants were administered a series of standardized measures of retrospective memory and executive functions. Results Individuals with PD demonstrated impaired prospective memory performance compared to the healthy adults, with a greater impairment demonstrated for the time-based tasks. Time-based prospective memory performance was moderately correlated with measures of executive functioning, but only the Stroop Neuropsychological Screening Test emerged as a unique predictor in a linear regression. Conclusions Findings are interpreted within the context of McDaniel and Einstein's (2000) multi-process theory to suggest that individuals with PD experience particular difficulty executing a future intention when the cue to execute the prescribed intention requires higher levels of executive control.

Raskin, Sarah A.; Woods, Steven Paul; Poquette, Amelia J.; McTaggart, April B.; Sethna, Jim; Williams, Rebecca C.; Troster, Alexander I.

2010-01-01

95

Event-based prospective memory deficits in individuals with high depressive symptomatology: Problems controlling attentional resources?  

PubMed

Depression has been found to be related to neurocognitive deficits in areas important to successful prospective memory (PM) performance, including executive function, attention, and retrospective memory. However, research specific to depression and PM has produced a mixed pattern of results. The current study further examined the task conditions in which event-based PM deficits may emerge in individuals with high depressive symptomatology (HDS) relative to individuals with low depressive symptomatology (LDS) and the capacity of HDS individuals to allocate attentional resources to event-based PM tasks. Sixty-four participants (32 HDS, 32 LDS) were required to make a PM response when target words were presented during an ongoing lexical decision task. When the importance of the ongoing task was emphasized, response time costs to the ongoing task, and PM accuracy, did not differ between the HDS and LDS groups. This finding is consistent with previous research demonstrating that event-based PM task accuracy is not always impaired by depression, even when the PM task is resource demanding. When the importance of the PM task was emphasized, costs to the ongoing task further increased for both groups, indicating an increased allocation of attentional resources to the PM task. Crucially, while a corresponding improvement in PM accuracy was observed in the LDS group when the importance of the PM task was emphasized, this was not true for the HDS group. The lack of improved PM accuracy in the HDS group compared with the LDS group despite evidence of increased cognitive resources allocated to PM tasks may have been due to inefficiency in the application of the allocated attention, a dimension likely related to executive function difficulties in depression. Qualitatively different resource allocation patterns may underlie PM monitoring in HDS versus LDS individuals. PMID:24848441

Li, Yanqi Ryan; Loft, Shayne; Weinborn, Michael; Maybery, Murray T

2014-08-01

96

Event-based simulation of neutron experiments: interference, entanglement and uncertainty relations  

NASA Astrophysics Data System (ADS)

We discuss a discrete-event simulation approach, which has been shown to give a unified cause-and-effect description of many quantum optics and single-neutron interferometry experiments. The event-based simulation algorithm does not require the knowledge of the solution of a wave equation of the whole system, yet reproduces the corresponding statistical distributions by generating detection events one-by-one. It is showm that single-particle interference and entanglement, two important quantum phenomena, emerge via information exchange between individual particles and devices such as beam splitters, polarizers and detectors. We demonstrate this by reproducing the results of several single-neutron interferometry experiments, including one that demonstrates interference and one that demonstrates the violation of a Bell-type inequality. We also present event-based simulation results of a single neutron experiment designed to test the validity of Ozawa's universally valid error-disturbance relation, an uncertainty relation derived using the theory of general quantum measurements.

Michielsen, Kristel; De Raedt, Hans

2014-04-01

97

The Link Between Alcohol Use and Aggression Toward Sexual Minorities: An Event-Based Analysis  

PubMed Central

The current study used an event-based assessment approach to examine the day-to-day relationship between heterosexual men’s alcohol consumption and perpetration of aggression toward sexual minorities. Participants were 199 heterosexual drinking men between the ages of 18–30 who completed (1) separate timeline followback interviews to assess alcohol use and aggression toward sexual minorities during the past year, and (2) written self-report measures of risk factors for aggression toward sexual minorities. Results indicated that aggression toward sexual minorities was twice as likely on a day when drinking was reported than on non-drinking days, with over 80% of alcohol-related aggressive acts perpetrated within the group context. Patterns of alcohol use (i.e., number of drinking days, mean drinks per drinking day, number of heavy drinking days) were not associated with perpetration after controlling for demographic variables and pertinent risk factors. Results suggest that it is the acute effects of alcohol, and not men’s patterns of alcohol consumption, that facilitate aggression toward sexual minorities. More importantly, these data are the first to support an event-based link between alcohol use and aggression toward sexual minorities (or any minority group), and provide the impetus for future research to examine risk factors and mechanisms for intoxicated aggression toward sexual minorities and other stigmatized groups.

Parrott, Dominic J.; Gallagher, Kathryn E.; Vincent, Wilson; Bakeman, Roger

2010-01-01

98

Event-based Plausibility Immediately Influences On-line Language Comprehension  

PubMed Central

In some theories of sentence comprehension, linguistically-relevant lexical knowledge such as selectional restrictions is privileged in terms of the time-course of its access and influence. We examined whether event knowledge computed by combining multiple concepts can rapidly influence language understanding even in the absence of selectional restriction violations. Specifically, we investigated whether instruments can combine with actions to influence comprehension of ensuing patients. Instrument-verb-patient triplets were created in a norming study designed to tap directly into event knowledge. In self-paced reading (Experiment 1), participants were faster to read patient nouns such as hair when they were typical of the instrument-action pair (Donna used the shampoo to wash vs. the hose to wash). Experiment 2 showed that these results were not due to direct instrument-patient relations. Experiment 3 replicated Experiment 1 using eyetracking, with effects of event typicality observed in first fixation and gaze durations on the patient noun. This research demonstrates that conceptual event-based expectations are computed and used rapidly and dynamically during on-line language comprehension. We discuss relationships among plausibility and predictability, as well as their implications. We conclude that selectional restrictions may be best considered as event-based conceptual knowledge, rather than lexical-grammatical knowledge.

Matsuki, Kazunaga; Chow, Tracy; Hare, Mary; Elman, Jeffrey L.; Scheepers, Christoph; McRae, Ken

2011-01-01

99

Event-Based Parareal: A data-flow based implementation of parareal  

SciTech Connect

Parareal is an iterative algorithm that, in effect, achieves temporal decomposition for a time-dependent system of differential or partial differential equations. A solution is obtained in a shorter wall-clock time, but at the expense of increased compute cycles. The algorithm combines a fine solver that solves the system to acceptable accuracy with an approximate coarse solver. The critical task for the successful implementation of parareal on any system is the development of a coarse solver that leads to convergence in a small number of iterations compared to the number of time slices in the full time interval, and is, at the same time, much faster than the fine solver. Fast coarse solvers may not lead to sufficiently rapid convergence, and slow coarse solvers may not lead to significant gains even if the number of iterations to convergence is satisfactory. We find that the difficulty of meeting these conflicting demands can be substantially eased by using a data-driven, event-based implementation of parareal instead of the conventional algorithm where solver tasks are executed sequentially. For given convergence properties, the event-based approach relaxes the speed requirements on the coarse solver by a factor of , where is the number of iterations required for a converged solution. This may, for many problems, lead to an efficient parareal implementation that would otherwise not be possible or would require substantial coarse solver development.

Berry, Lee A [ORNL; Elwasif, Wael R [ORNL; Reynolds-Barredo, J. [University of Alaska; University Carlos III de Madrid; Samaddar, D. [ITER Organization, Saint Paul Lez Durance, France; Sanchez, R. [Universidad Carlos III, Madrid, Spain; Newman, David E [University of Alaska; Chen, J. [Princeton Plasma Physics Laboratory (PPPL)

2012-01-01

100

An event based real-time conditioned predictor of hourly hyetograph characteristics  

NASA Astrophysics Data System (ADS)

Setting up stochastic models capable to perform real-time conditioned rainfall predictions at high temporal resolution is crucial in developing hydro-geological early warning systems. Indeed, several rainfall-induced dangerous phenomena taking place at catchment or slope scale, such as flash floods and debris flows, may be triggered by relatively short rainfall events. The small spatial resolution at which the predictions are needed does not allow to make use neither of rainfall forecasts based on global circulation models, nor of data coming from radar sensors. Thus, the most reliable source of information is still represented by rain gauges installed at the site to be monitored. Modelling of point rainfall series has been addressed in hydrological literature with two major approaches: cluster-based models and event-based models. In this paper, using rainfall data observed in real time during a storm, a stochastic predictor of its future evolution is presented. The core of the predictor consists in an event based stochastic model. An event based approach is adopted, since it permits to identify a storm on the basis of the observed series of rainfall data and to calculate univocally its probability, thus allowing to perform the desired predictions in a relatively straightforward way. With this approach, predictions can be conditioned only to the part of real time observed rainfall data on which future evolution of the storm depends, in the stochastic sense. Conversely, cluster-based stochastic models, widely used for the generation of synthetic rainfall series, are not trivially suitable for real-time conditioned predictions, since they do not allow to evaluate unambiguously the probability of an observed hyetograph, because it can be generated by more than one combination of rain cells. The proposed model has been calibrated with hourly rainfall series of the rain gauges of the meteorological alert network of the Civil Protection Agency of Campania, Southern Italy. The statistical hypotheses on which the model is based have been checked by classical statistical tests, such as Blum-Kiefer-Rosenblatt test for independence. Furthermore, the information about the observed internal structure of the storm, at hourly scale, has been coupled with the external structure model, allowing to perform conditioned predictions of hydrologic response indexes, depending on the future evolution of hyetograph shape.

Giorgio, Massimiliano; Greco, Roberto

2010-05-01

101

On the Application of Different Event-Based Sampling Strategies to the Control of a Simple Industrial Process  

PubMed Central

This paper is an experimental study of the utilization of different event-based strategies for the automatic control of a simple but very representative industrial process: the level control of a tank. In an event-based control approach it is the triggering of a specific event, and not the time, that instructs the sensor to send the current state of the process to the controller, and the controller to compute a new control action and send it to the actuator. In the document, five control strategies based on different event-based sampling techniques are described, compared, and contrasted with a classical time-based control approach and a hybrid one. The common denominator in the time, the hybrid, and the event-based control approaches is the controller: a proportional-integral algorithm with adaptations depending on the selected control approach. To compare and contrast each one of the hybrid and the pure event-based control algorithms with the time-based counterpart, the two tasks that a control strategy must achieve (set-point following and disturbance rejection) are independently analyzed. The experimental study provides new proof concerning the ability of event-based control strategies to minimize the data exchange among the control agents (sensors, controllers, actuators) when an error-free control of the process is not a hard requirement.

Sanchez, Jose; Guarnes, Miguel Angel; Dormido, Sebastian

2009-01-01

102

Qualitative Event-Based Diagnosis: Case Study on the Second International Diagnostic Competition  

NASA Technical Reports Server (NTRS)

We describe a diagnosis algorithm entered into the Second International Diagnostic Competition. We focus on the first diagnostic problem of the industrial track of the competition in which a diagnosis algorithm must detect, isolate, and identify faults in an electrical power distribution testbed and provide corresponding recovery recommendations. The diagnosis algorithm embodies a model-based approach, centered around qualitative event-based fault isolation. Faults produce deviations in measured values from model-predicted values. The sequence of these deviations is matched to those predicted by the model in order to isolate faults. We augment this approach with model-based fault identification, which determines fault parameters and helps to further isolate faults. We describe the diagnosis approach, provide diagnosis results from running the algorithm on provided example scenarios, and discuss the issues faced, and lessons learned, from implementing the approach

Daigle, Matthew; Roychoudhury, Indranil

2010-01-01

103

Modelling of eternal and internal intermittence of rainfall data via a simple event based stochastic model  

NASA Astrophysics Data System (ADS)

In this paper, an event-based model is presented which enables to fully and accurately describe (in probabilistic sense) both internal and external time intermittence of point rainfall data series at sub-daily timescale. The proposed approach allows identifying a series of storms in a rainfall height data series and to formulate unambiguously the probability of the observed hyetograph of each storm. The calibration of the proposed methodology is carried out on the basis of time series of point rainfall data provided by the rain gauges of the meteorological warning network of the civil protection agency of Campania Region. All the hypotheses upon which the model relies have been checked using proper statistical tests. The application of the proposed model for generating synthetic data as well as for performing real time prediction of future temporal evolution of local rainfall is also discussed.

Giorgio, M.; Greco, R.

2012-04-01

104

Event-based prospective memory in newly diagnosed, drug-naive Parkinson's disease patients.  

PubMed

The present study investigated memory for intention in individuals with Parkinson's disease (PD) who were newly diagnosed and not yet treated to avoid the effect of therapy as a potential confounding variable. A comprehensive neuropsychological battery and an event-based prospective memory task were administered to 41 subjects with de novo PD and 40 control subjects. Separate scores were computed for correct execution of intended action (prospective component) and recall of intention (retrospective component). PD patients performed marginally worse (p = .053) than controls on the prospective component of the task. On the other hand, the performance of the two groups was comparable for the retrospective component. Neuropsychological findings revealed lower performance of the PD group in episodic memory and in some measures of executive functions. These results suggested a subtle prospective memory dysfunction present at the initial stage of PD, which may be related to disruption of fronto-striatal circuitry. PMID:22014082

Pagni, Cristina; Frosini, Daniela; Ceravolo, Roberto; Giunti, Giulia; Unti, Elisa; Poletti, Michele; McClintock, Shawn M; Murri, Luigi; Bonuccelli, Ubaldo; Tognoni, Gloria

2011-11-01

105

Improvement of hydrological flood forecasting through an event based output correction method  

NASA Astrophysics Data System (ADS)

This contribution presents an output correction method for hydrological models. A conceptualisation of the method is presented and tested in an alpine basin in Salzburg, Austria. The aim is to develop a method which is not prone to the drawbacks of autoregressive models. Output correction methods are an attractive option for improving hydrological predictions. They are complementary to the main modelling process and do not interfere with the modelling process itself. In general, output correction models estimate the future error of a prediction and use the estimation to improve the given prediction. Different estimation techniques are available dependent on the utilized information and the estimation procedure itself. Autoregressive error models are widely used for such corrections. Autoregressive models with exogenous inputs (ARX) allow the use of additional information for the error modelling, e.g. measurements from upper basins or predicted input-signals. Autoregressive models do however exhibit deficiencies, since the errors of hydrological models do generally not behave in an autoregressive manner. The decay of the error is usually different from an autoregressive function and furthermore the residuals exhibit different patterns under different circumstances. As for an example, one might consider different error-propagation behaviours under high- and low-flow situations or snow melt driven conditions. This contribution presents a conceptualisation of an event-based correction model and focuses on flood events only. The correction model uses information about the history of the residuals and exogenous variables to give an error-estimation. The structure and parameters of the correction models can be adapted to given event classes. An event-class is a set of flood events that exhibit a similar pattern for the residuals or the hydrological conditions. In total, four different event-classes have been identified in this study. Each of them represents a different hydrological state, which is associated with different error sources and behaviours. Within each event-class, a set of ARX models are applied to simulate the behaviour of the error. This approach makes the correction model highly adaptable and allows for the representation of different behavioural patterns of the error. The procedure is tested and compared with an auto regressive model of first order. It is shown that the event-based correction method can improve the prediction significantly, given that an event is classified correctly.

Klotz, Daniel; Nachtnebel, Hans Peter

2014-05-01

106

Typhoon event-based evolutionary fuzzy inference model for flood stage forecasting  

NASA Astrophysics Data System (ADS)

This study proposes an evolutionary fuzzy inference model that combines a fuzzy inference model, genetic programming (GP), and a genetic algorithm (GA) to forecast flood stages during typhoons. The number of fuzzy inference rules in the proposed approach is based on the number of typhoon flood events. The consequent part of the rule was formed by constructing GP models that depict the rainfall-stage relationship of a specific flood event, whereas the GA was used to search the parameters of the fuzzy membership functions in the premise part of the rule. This study uses the proposed event-based evolutionary fuzzy inference model to forecast the typhoon flood stages of Wu River in Taiwan. Forecasting results based on stage hydrographs and performance indices verify the forecasting ability of the proposed model. This study also identifies the weights of triggered fuzzy rules during the fuzzy inference process, showing that a fuzzy rule is triggered according to the characteristics of the flood event that forms the rule. Moreover, physical explanation of the proposed evolutionary fuzzy inference model was discussed.

Chen, Chang-Shian; Jhong, You-Da; Wu, Ting-Ying; Chen, Shien-Tsung

2013-05-01

107

Fluence-based and microdosimetric event-based methods for radiation protection in space  

NASA Technical Reports Server (NTRS)

The National Council on Radiation Protection and Measurements (NCRP) has recently published a report (Report #137) that discusses various aspects of the concepts used in radiation protection and the difficulties in measuring the radiation environment in spacecraft for the estimation of radiation risk to space travelers. Two novel dosimetric methodologies, fluence-based and microdosimetric event-based methods, are discussed and evaluated, along with the more conventional quality factor/LET method. It was concluded that for the present, any reason to switch to a new methodology is not compelling. It is suggested that because of certain drawbacks in the presently-used conventional method, these alternative methodologies should be kept in mind. As new data become available and dosimetric techniques become more refined, the question should be revisited and that in the future, significant improvement might be realized. In addition, such concepts as equivalent dose and organ dose equivalent are discussed and various problems regarding the measurement/estimation of these quantities are presented.

Curtis, Stanley B.; Meinhold, C. B. (Principal Investigator)

2002-01-01

108

Simulation of Greenhouse Climate Monitoring and Control with Wireless Sensor Network and Event-Based Control  

PubMed Central

Monitoring and control of the greenhouse environment play a decisive role in greenhouse production processes. Assurance of optimal climate conditions has a direct influence on crop growth performance, but it usually increases the required equipment cost. Traditionally, greenhouse installations have required a great effort to connect and distribute all the sensors and data acquisition systems. These installations need many data and power wires to be distributed along the greenhouses, making the system complex and expensive. For this reason, and others such as unavailability of distributed actuators, only individual sensors are usually located in a fixed point that is selected as representative of the overall greenhouse dynamics. On the other hand, the actuation system in greenhouses is usually composed by mechanical devices controlled by relays, being desirable to reduce the number of commutations of the control signals from security and economical point of views. Therefore, and in order to face these drawbacks, this paper describes how the greenhouse climate control can be represented as an event-based system in combination with wireless sensor networks, where low-frequency dynamics variables have to be controlled and control actions are mainly calculated against events produced by external disturbances. The proposed control system allows saving costs related with wear minimization and prolonging the actuator life, but keeping promising performance results. Analysis and conclusions are given by means of simulation results.

Pawlowski, Andrzej; Guzman, Jose Luis; Rodriguez, Francisco; Berenguel, Manuel; Sanchez, Jose; Dormido, Sebastian

2009-01-01

109

Assessing the Continuum of Event-Based Biosurveillance Through an Operational Lens  

SciTech Connect

This research follows the Updated Guidelines for Evaluating Public Health Surveillance Systems, Recommendations from the Guidelines Working Group, published by the Centers for Disease Control and Prevention nearly a decade ago. Since then, models have been developed and complex systems have evolved with a breadth of disparate data to detect or forecast chemical, biological, and radiological events that have significant impact in the One Health landscape. How the attributes identified in 2001 relate to the new range of event-based biosurveillance (EBB) technologies is unclear. This manuscript frames the continuum of EBB methods, models, and constructs through an operational lens (i.e., aspects and attributes associated with operational considerations in the development, testing, and validation of the EBB methods and models and their use in an operational environment). A 2-day subject matter expert workshop was held to scientifically identify, develop, and vet a set of attributes for the broad range of such operational considerations. Workshop participants identified and described comprehensive attributes for the characterization of EBB. The identified attributes are: (1) event, (2) readiness, (3) operational aspects, (4) geographic coverage, (5) population coverage, (6) input data, (7) output, and (8) cost. Ultimately, the analyses herein discuss the broad scope, complexity, and relevant issues germane to EBB useful in an operational environment.

Corley, Courtney D.; Lancaster, Mary J.; Brigantic, Robert T.; Chung, James S.; Walters, Ronald A.; Arthur, Ray; Bruckner-Lea, Cindy J.; Calapristi, Augustin J.; Dowling, Glenn; Hartley, David M.; Kennedy, Shaun; Kircher, Amy; Klucking, Sara; Lee, Eva K.; McKenzie, Taylor K.; Nelson, Noele P.; Olsen, Jennifer; Pancerella, Carmen M.; Quitugua, Teresa N.; Reed, Jeremy T.; Thomas, Carla S.

2012-03-28

110

Selection of intense rainfall events based on intensity thresholds and lightning data in Switzerland  

NASA Astrophysics Data System (ADS)

This paper presents a method to identify intense warm season storms with convective character based on intensity thresholds and the presence of lightning, and analyzes their statistical properties. Long records of precipitation and lightning data at 4 stations and 10 min resolution in different climatological regions in Switzerland are used. Our premise is that thunderstorms associated with lightning generate bursts of high rainfall intensity. We divided all recorded storms into those accompanied by lightning and those without lightning and found the threshold I* that separates intense events based on peak 10 min intensity Ip ? I* for a chosen misclassification rate ?. The performance and robustness of the selection method was tested by investigating the inter-annual variability of I* and its relation to the frequency of lightning strikes. The probability distributions of the main storm properties (rainfall depth R, event duration D, average storm intensity Ia and peak 10 min intensity Ip) for the intense storm subsets show that the event average and peak intensities are significantly different between the stations. Non-parametric correlations between the main storm properties were estimated for intense storms and all storms including stratiform rain. The differences in the correlations between storm subsets are greater than those between stations, which indicates that care must be exercised not to mix events of different origin when they are sampled for multivariate analysis, for example, copula fitting to rainfall data.

Gaál, L.; Molnar, P.; Szolgay, J.

2014-05-01

111

Selection of intense rainfall events based on intensity thresholds and lightning data in Switzerland  

NASA Astrophysics Data System (ADS)

This paper presents a method to identify intense warm season storms of convective character based on intensity thresholds and lightning, and analyzes their statistical properties. Long records of precipitation and lightning data at 4 stations and 10 min resolution in different climatological regions in Switzerland are used. Our premise is that thunderstorms associated with lightning generate bursts of high rainfall intensity. We divided all storms into those accompanied by lightning and those without lightning and found the threshold I* that separates intense events based on peak 10 min intensity Ip ? I* for a chosen misclassification rate ?. The performance and robustness of the selection method was tested by investigating the inter-annual variability of I* and its relation to the frequency of lightning strikes. The probability distributions of the main storm properties (rainfall depth R, event duration D, average storm intensity Ia and peak 10 min intensity Ip) for the intense storm subsets show that the event average and peak intensities are significantly different between the stations, and highest in Lugano in southern Switzerland. Non-parametric correlations between the main storm properties were estimated for the subsets of intense storms and all storms including stratiform rain. The differences in the correlations between storm subsets are greater than those between stations, which indicates that care must be exercised not to mix events when they are sampled for multivariate analysis, e.g. copula fitting to rainfall data.

Gaal, L.; Molnar, P.; Szolgay, J.

2014-01-01

112

Agreement between event-based and trend-based glaucoma progression analyses  

PubMed Central

Purpose To evaluate the agreement between event- and trend-based analyses to determine visual field (VF) progression in glaucoma. Methods VFs of 175 glaucoma eyes with ?5 VFs were analyzed by proprietary software of VF analyzer to determine progression. Agreement (?) between trend-based analysis of VF index (VFI) and event-based analysis (glaucoma progression analysis, GPA) was evaluated. For eyes progressing by event- and trend-based methods, time to progression by two methods was calculated. Results Median number of VFs per eye was 7 and follow-up 7.5 years. GPA classified 101 eyes (57.7%) as stable, 30 eyes (17.1%) as possible and 44 eyes (25.2%) as likely progression. Trend-based analysis classified 122 eyes (69.7%) as stable (slope >?1% per year or any slope magnitude with P>0.05), 53 eyes (30.3%) as progressing with slope

Rao, H L; Kumbar, T; Kumar, A U; Babu, J G; Senthil, S; Garudadri, C S

2013-01-01

113

Coupling urban event-based and catchment continuous modelling for combined sewer overflow river impact assessment  

NASA Astrophysics Data System (ADS)

Since the Water Framework Directive (WFD) was passed in year 2000, the protection of water bodies in the EU must be understood in a completely different way. Regarding to combined sewer overflows (CSOs) from urban drainage networks, the WFD implies that CSOs cannot be accepted because of their intrinsic features, but must be assessed for their impact on the receiving water bodies in agreement with specific environmental aims. Consequently, both, the urban system and the receiving one must be jointly analysed to evaluate their impact. In this context, a coupled scheme is presented in this paper to assess the CSOs impact in a river system in Torrelavega (Spain). First, an urban model is developed to characterise statistically the CSOs frequency, volume and duration. The main feature of this first model is the fact of being event-based: the system is modelled with some built synthetic storms which cover adequately the probability range of the main rainfall descriptors, i.e., rainfall event volume and peak intensity. Thus, CSOs are characterised in terms of their occurrence probability. Secondly, a continuous and distributed basin model is built to assess the river response at different points in the river network. This model was calibrated initially on a daily scale and downscaled later to the hourly scale. The main objective of this second element of the scheme is to provide the most likely state of the receiving river when a CSO occurs. By combining results of both models, CSO and river flows are homogeneously characterised from a statistical point of view. Finally, results from both models were coupled to estimate the final concentration of some analysed pollutants (the biochemical oxygen demand, BOD, and the total ammonium, NH4+), in the river just after the spills.

Andrés-Doménech, I.; Múnera, J. C.; Francés, F.; Marco, J. B.

2010-05-01

114

Coupling urban event-based and catchment continuous modelling for combined sewer overflow river impact assessment  

NASA Astrophysics Data System (ADS)

Since Water Framework Directive (WFD) was passed in year 2000, the conservation of water bodies in the EU must be understood in a completely different way. Regarding to combined sewer overflows (CSOs) from urban drainage networks, the WFD implies that we cannot accept CSOs because of their intrinsic features, but they must be assessed for their impact on the receiving water bodies in agreement with specific environmental aims. Consequently, both, urban system and the receiving water body must be jointly analysed to evaluate the environmental impact generated on the latter. In this context, a coupled scheme is presented in this paper to assess the CSOs impact on a river system in Torrelavega (Spain). First, a urban model is developed to statistically characterise the CSOs frequency, volume and duration. The main feature of this first model is the fact of being event-based: the system is modelled with some built synthetic storms which cover adequately the probability range of the main rainfall descriptors, i.e., rainfall event volume and peak intensity. Thus, CSOs are characterised in terms of their occurrence probability. Secondly, a continuous and distributed basin model is built to assess river response at different points in the river network. This model was calibrated initially on a daily scale and downscaled later to hourly scale. The main objective of this second element of the scheme is to provide the most likely state of the receiving river when a CSO occurs. By combining results of both models, CSO and river flows are homogeneously characterised from a statistical point of view. Finally, results from both models were coupled to estimate the final concentration of some analysed pollutants (biochemical oxygen demand, BOD, and total ammonium, NH4+), within the river just after the spills.

Andrés-Doménech, I.; Múnera, J. C.; Francés, F.; Marco, J. B.

2010-10-01

115

Identify Alternative Splicing Events Based on Position-Specific Evolutionary Conservation  

PubMed Central

The evolution of eukaryotes is accompanied by the increased complexity of alternative splicing which greatly expands genome information. One of the greatest challenges in the post-genome era is a complete revelation of human transcriptome with consideration of alternative splicing. Here, we introduce a comparative genomics approach to systemically identify alternative splicing events based on the differential evolutionary conservation between exons and introns and the high-quality annotation of the ENCODE regions. Specifically, we focus on exons that are included in some transcripts but are completely spliced out for others and we call them conditional exons. First, we characterize distinguishing features among conditional exons, constitutive exons and introns. One of the most important features is the position-specific conservation score. There are dramatic differences in conservation scores between conditional exons and constitutive exons. More importantly, the differences are position-specific. For flanking intronic regions, the differences between conditional exons and constitutive exons are also position-specific. Using the Random Forests algorithm, we can classify conditional exons with high specificities (97% for the identification of conditional exons from intron regions and 95% for the classification of known exons) and fair sensitivities (64% and 32% respectively). We applied the method to the human genome and identified 39,640 introns that actually contain conditional exons and classified 8,813 conditional exons from the current RefSeq exon list. Among those, 31,673 introns containing conditional exons and 5,294 conditional exons classified from known exons cannot be inferred from RefSeq, UCSC or Ensembl annotations. Some of these de novo predictions were experimentally verified.

Chen, Liang; Zheng, Sika

2008-01-01

116

Monetary incentive effects on event-based prospective memory three months after traumatic brain injury in children  

Microsoft Academic Search

Information regarding the remediation of event-based prospective memory (EB-PM) impairments following pediatric traumatic brain injury (TBI) is scarce. Addressing this, two levels of monetary incentives were used to improve EB-PM in children ages 7 to 16 years with orthopedic injuries (OI, n = 51), or moderate (n = 25) and severe (n = 39) TBI at approximately 3 months postinjury.

Stephen R. McCauley; Claudia Pedroza; Sandra B. Chapman; Lori G. Cook; Ana C. Vásquez; Harvey S. Levin

2011-01-01

117

Modulation of a Fronto-Parietal Network in Event-Based Prospective Memory: An rTMS Study  

ERIC Educational Resources Information Center

Event-based prospective memory (PM) is a multi-component process that requires remembering the delayed execution of an intended action in response to a pre-specified PM cue, while being actively engaged in an ongoing task. Some neuroimaging studies have suggested that both prefrontal and parietal areas are involved in the maintenance and…

Bisiacchi, P. S.; Cona, G.; Schiff, S.; Basso, D.

2011-01-01

118

On the Relationship Between Effort Toward an Ongoing Task and Cue Detection in Event-Based Prospective Memory  

ERIC Educational Resources Information Center

In recent theories of event-based prospective memory, researchers have debated what degree of resources are necessary to identify a cue as related to a previously established intention. In order to simulate natural variations in attention, the authors manipulated effort toward an ongoing cognitive task in which intention-related cues were embedded…

Marsh, Richard L.; Hicks, Jason L.; Cook, Gabriel I.

2005-01-01

119

On the Relationship Between Effort Toward an Ongoing Task and Cue Detection in Event-Based Prospective Memory  

Microsoft Academic Search

In recent theories of event-based prospective memory, researchers have debated what degree of resources are necessary to identify a cue as related to a previously established intention. In order to simulate natural variations in attention, the authors manipulated effort toward an ongoing cognitive task in which intention-related cues were embedded in 3 experiments. High effort toward the ongoing task resulted

Richard L. Marsh; Jason L. Hicks; Gabriel I. Cook

2005-01-01

120

A two?process model of strategic monitoring in event?based prospective memory: Activation\\/retrieval mode and checking  

Microsoft Academic Search

Theorists have suggested that individuals may remember to execute event?based intended actions by deploying executive or attentional resources to monitor for the markers or target events that indicate that it is appropriate to execute the intended actions (e.g., McDaniel & Einstein, 2000; Shallice & Burgess, 1991), but these strategic monitoring views are not specific about the processes that strategic monitoring

Melissa J. Guynn

2003-01-01

121

Comparison of event-based landslide inventory maps obtained interpreting satellite images and aerial photographs  

NASA Astrophysics Data System (ADS)

Landslide inventory maps are a common type of map used for geomorphological investigations, land planning, and hazard and risk assessment. Landslide inventory maps covering medium to large areas are obtained primarily exploiting traditional geomorphological techniques. These techniques combine the visual and heuristic interpretation of stereoscopic aerial photographs with more or less extensive field investigations. Aerial photographs most commonly used to prepare landslide inventory maps range in scale from about 1:10,000 to about 1:40,000. Interpretation of satellite images is a relatively recent, powerful tool to obtain information of the Earth surface potentially useful for the production of landslide inventory maps. The usefulness of satellite information - and the associated technology - for the identification of landslides and the production of landslide inventory maps, remains largely unexplored. In this context, it is of interest to investigate the type, quantity, and quality of the information that can be retrieved analyzing images taken by the last generation of high and very-high resolution satellite sensors, and to compare this information with the information obtained from the analysis of traditional stereoscopic aerial photographs, or in the field. In the framework of the MORFEO project for the exploitation of Earth Observation data and technology for landslide identification and risk assessment, of the Italian Space Agency, we have compared two event-based landslide inventory maps prepared exploiting two different techniques. The two maps portray the geographical distribution and types of landslides triggered by rainfall in the period from November 2004 to May 2005 in the Collazzone area, Umbria, central Italy. The first map was prepared through reconnaissance field surveys carried out mostly along roads. The second map was obtained through the combined visual interpretation of 1:10,000 scale, colour ortho-photo maps, and images taken by the IKONOS high-resolution satellite. The comparison was executed considering: (i) descriptive landslide statistics, (ii) cartographic matching or mismatching, to quantify positional and dimensional errors (over-estimated or under-estimated landslide size), and (iii) differences in the frequency-area statistics, that quantify the number of landslides in different size classes. We discuss the results obtained in view of their importance for the production of landslide inventory maps. We emphasize advantages and limitations of the different information used, and of the adopted approaches and techniques.

Fiorucci, Federica; Cardinali, Mauro; Carlà Roberto; Mondini, Alessandro; Santurri, Leonardo; Guzzetti, Fausto

2010-05-01

122

Practical Implementation of a Test of Event-Based Corpuscular Model as an Alternative to Quantum Mechanics  

NASA Astrophysics Data System (ADS)

We describe in detail the first experimental test that distinguishes between an event-based corpuscular model of the interaction of photons with matter and quantum mechanics. The test looks at the interference that results as a single photon passes through a Mach-Zehnder interferometer. The experimental results, obtained with a low-noise single-photon source, agree with the predictions of standard quantum mechanics.

Polyakov, Sergey V.; Piacentini, Fabrizio; Traina, Paolo; Degiovanni, Ivo P.; Migdall, Alan; Brida, Giorgio; Genovese, Marco

2013-08-01

123

ASYNCAR, a radio-controlled vehicle for asynchronous experiments implementation of an event-based cruise control  

Microsoft Academic Search

The main contribution of this paper is to develop an experimental platform in order to test some event-based control strategies. Contrary to the time-triggered fashion which calculates the control signal at each sampling time, an event-driven controller updates the control signal only when required. This theoretically allows to reduce the computational cost. In this paper, we propose to firstly test

Sylvain Durand; Julien Minet; Jose Fermi Guerrero Castellanos; Nicolas Marchand

2011-01-01

124

Differential involvement of regions of rostral prefrontal cortex (Brodmann area 10) in time- and event-based prospective memory  

Microsoft Academic Search

Rostral prefrontal cortex (approximating Brodmann area 10) has been shown repeatedly to have a role in the maintenance and realization of delayed intentions that are triggered by event cues (i.e., event-based prospective memory). The cerebral organization of the processes associated with the use of time cues (time-based prospective memory) has however received less attention. In two positron emission tomography (PET)

Jiro Okuda; Toshikatsu Fujii; Hiroya Ohtake; Takashi Tsukiura; Atsushi Yamadori; Christopher D. Frith; Paul W. Burgess

2007-01-01

125

Incentive Effects on Event-Based Prospective Memory Performance in Children and Adolescents with Traumatic Brain Injury  

PubMed Central

Prospective memory (PM) is the formation of an intention and remembering to perform this intention at a future time or in response to specific cues. PM tasks are a ubiquitous part of daily life. Currently, there is a paucity of information regarding PM impairments in children with traumatic brain injury (TBI) and less empirical evidence regarding effective remediation strategies to mitigate these impairments. The present study employed two levels of a motivational enhancement (i.e., a monetary incentive) to determine if event-based PM could be improved in children with severe TBI. In a cross-over design, children with orthopedic injuries and mild or severe TBI were compared on two levels of incentive (dollars versus pennies) given in response to accurate performance. All three groups performed significantly better under the high- versus low-motivation conditions. However, the severe TBI group’s high-motivation condition performance remained significantly below the low-motivation condition performance of the orthopedic injury group. PM scores were positively and significantly related to age-attest, but there were no age-at-injury or time-postinjury effects. Overall, these results suggest that event-based PM can be significantly improved in children with severe TBI.

McCauley, Stephen R.; McDaniel, Mark A.; Pedroza, Claudia; Chapman, Sandra B.; Levin, Harvey S.

2011-01-01

126

Event-based Prospective Memory and Everyday Forgetting in Healthy Older Adults and Individuals with Mild Cognitive Impairment  

PubMed Central

An event-based non-focal task was used to evaluate prospective memory (PM), and the relationship between PM, neuropsychological testing data and everyday forgetting. Twenty-four participants with mild cognitive impairment (MCI) and 24 age and education matched cognitively healthy adults responded to a non-focal PM cue, while completing an ongoing working memory task. Neuropsychological testing data and self- and informant-report of frequency of forgetting were also gathered. Compared to healthy adults, the MCI participants exhibited significantly poorer prospective remembering and ongoing task performance, despite similar self-reported effort directed to the PM task. Both self- and informant-report indicated that the MCI group was experiencing a higher frequency of everyday forgetting than the healthy adult group. Self-report of everyday forgetting was correlated with PM task performance for the healthy adults, but not the MCI participants. For the healthy adults, correlational analyses also showed significant relationships between PM accuracy and tests of memory and executive functioning, suggesting that both spontaneous retrieval processes and effortful, strategic monitoring may be important in supporting prospective remembering for this non-focal PM task. The stronger relationships between PM accuracy and memory and language tests for the MCI group suggests that their poorer event-based prospective remembering might be linked to impaired spontaneous retrieval processes, which are thought to be supported by medial temporal structures.

Tam, Joyce W.; Schmitter-Edgecombe, Maureen

2013-01-01

127

Event-based knowledge elicitation of operating room management decision-making using scenarios adapted from information systems data  

PubMed Central

Background No systematic process has previously been described for a needs assessment that identifies the operating room (OR) management decisions made by the anesthesiologists and nurse managers at a facility that do not maximize the efficiency of use of OR time. We evaluated whether event-based knowledge elicitation can be used practically for rapid assessment of OR management decision-making at facilities, whether scenarios can be adapted automatically from information systems data, and the usefulness of the approach. Methods A process of event-based knowledge elicitation was developed to assess OR management decision-making that may reduce the efficiency of use of OR time. Hypothetical scenarios addressing every OR management decision influencing OR efficiency were created from published examples. Scenarios are adapted, so that cues about conditions are accurate and appropriate for each facility (e.g., if OR 1 is used as an example in a scenario, the listed procedure is a type of procedure performed at the facility in OR 1). Adaptation is performed automatically using the facility's OR information system or anesthesia information management system (AIMS) data for most scenarios (43 of 45). Performing the needs assessment takes approximately 1 hour of local managers' time while they decide if their decisions are consistent with the described scenarios. A table of contents of the indexed scenarios is created automatically, providing a simple version of problem solving using case-based reasoning. For example, a new OR manager wanting to know the best way to decide whether to move a case can look in the chapter on "Moving Cases on the Day of Surgery" to find a scenario that describes the situation being encountered. Results Scenarios have been adapted and used at 22 hospitals. Few changes in decisions were needed to increase the efficiency of use of OR time. The few changes were heterogeneous among hospitals, showing the usefulness of individualized assessments. Conclusions Our technical advance is the development and use of automated event-based knowledge elicitation to identify suboptimal OR management decisions that decrease the efficiency of use of OR time. The adapted scenarios can be used in future decision-making.

2011-01-01

128

Getting to know your neighbors: unsupervised learning of topography from real-world, event-based input.  

PubMed

Biological neural systems must grow their own connections and maintain topological relations between elements that are related to the sensory input surface. Artificial systems have traditionally prewired such maps, but the sensor arrangement is not always known and can be expensive to specify before run time. Here we present a method for learning and updating topographic maps in systems comprising modular, event-based elements. Using an unsupervised neural spike-timing-based learning rule combined with Hebbian learning, our algorithm uses the spatiotemporal coherence of the external world to train its network. It improves on existing algorithms by not assuming a known topography of the target map and includes a novel method for automatically detecting edge elements. We show how, for stimuli that are small relative to the sensor resolution, the temporal learning window parameters can be determined without using any user-specified constants. For stimuli that are larger relative to the sensor resolution, we provide a parameter extraction method that generally outperforms the small-stimulus method but requires one user-specified constant. The algorithm was tested on real data from a 64 x 64-pixel section of an event-based temporal contrast silicon retina and a 360-tile tactile luminous floor. It learned 95.8% of the correct neighborhood relations for the silicon retina within about 400 seconds of real-world input from a driving scene and 98.1% correct for the sensory floor after about 160 minutes of human pedestrian traffic. Residual errors occurred in regions receiving little or ambiguous input, and the learned topological representations were able to update automatically in response to simulated damage. Our algorithm has applications in the design of modular autonomous systems in which the interfaces between components are learned during operation rather than at design time. PMID:19431283

Boerlin, Martin; Delbruck, Tobi; Eng, Kynan

2009-01-01

129

Event-based prospective memory is independently associated with self-report of medication management in older adults.  

PubMed

Background: Identifying potentially modifiable risk factors for medication non-adherence in older adults is important in order to enhance screening and intervention efforts designed to improve medication-taking behavior and health outcomes. The current study sought to determine the unique contribution of prospective memory (PM) (i.e. 'remembering to remember') to successful self-reported medication management in older adults.Methods: Sixty-five older adults with current medication prescriptions completed a comprehensive research evaluation of sociodemographic, psychiatric, and neurocognitive functioning, which included the memory for adherence to medication scale (MAMS), prospective and retrospective memory questionnaire (PRMQ), and a performance-based measure of PM that measured both semantically related and semantically unrelated cue-intention (i.e. when-what) pairings.Results: A series of hierarchical regressions controlling for biopsychosocial, other neurocognitive, and medication-related factors showed that elevated complaints on the PM scale of the PRMQ and worse performance on an objective semantically unrelated event-based PM task were independent predictors of poorer medication adherence as measured by the MAMS.Conclusions: PM plays an important role in self-report of successful medication management among older adults. Findings may have implications for screening for older individuals 'at risk' of non-adherence, as well as the development of PM-based interventions to improve medication adherence and, ultimately, long-term health outcomes in older adults. PMID:24410357

Woods, Steven Paul; Weinborn, Michael; Maxwell, Brenton R; Gummery, Alice; Mo, Kevin; Ng, Amanda R J; Bucks, Romola S

2014-08-01

130

Modulation of a fronto-parietal network in event-based prospective memory: an rTMS study.  

PubMed

Event-based prospective memory (PM) is a multi-component process that requires remembering the delayed execution of an intended action in response to a pre-specified PM cue, while being actively engaged in an ongoing task. Some neuroimaging studies have suggested that both prefrontal and parietal areas are involved in the maintenance and realization of delayed intentions. In the present study, transcranial magnetic stimulation (TMS) was used to investigate the causal involvement of frontal and parietal areas in different stages of the PM process (in particular, target checking and intention retrieval), and to determine the specific contribution of these regions to PM performance. Our results demonstrate that repetitive TMS (rTMS) interferes with prospective memory performance when applied at 150-350 ms to the right dorsolateral prefrontal cortex (DLPFC), and at 400-600 ms when applied to the left posterior parietal cortex (PPC). The present study provides clear evidence that the right DLPFC plays a crucial role in early components of the PM process (target checking), while the left PPC seems to be mainly involved in later processes, such as the retrieval of the intended action. PMID:21609726

Bisiacchi, P S; Cona, G; Schiff, S; Basso, D

2011-07-01

131

Deficits in cue detection underlie event-based prospective memory impairment in major depression: an eye tracking study.  

PubMed

This study examined the cue detection in the non-focal event-based prospective memory (PM) of individuals with and without a major depressive disorder using behavioural and eye tracking assessments. The participants were instructed to search on each trial for a different target stimulus that could be present or absent and to make prospective responses to the cue object. PM tasks included cue only and target plus cue, whereas ongoing tasks included target only and distracter only. The results showed that a) participants with depression performed more poorly than those without depression in PM; b) participants with depression showed more fixations and longer total and average fixation durations in both ongoing and PM conditions; c) participants with depression had lower scores on accuracy in target-plus-cue trials than in cue-only trials and had a higher gaze rate of targets on hits and misses in target-plus-cue trials than did those without depression. The results indicate that the state of depression may impair top-down cognitive control function, which in turn results in particular deficits in the engagement of monitoring for PM cues. PMID:23477903

Chen, Siyi; Zhou, Renlai; Cui, Hong; Chen, Xinyin

2013-10-30

132

Event-based minimum-time control of oscillatory neuron models: phase randomization, maximal spike rate increase, and desynchronization.  

PubMed

We present an event-based feedback control method for randomizing the asymptotic phase of oscillatory neurons. Phase randomization is achieved by driving the neuron's state to its phaseless set, a point at which its phase is undefined and is extremely sensitive to background noise. We consider the biologically relevant case of a fixed magnitude constraint on the stimulus signal, and show how the control objective can be accomplished in minimum time. The control synthesis problem is addressed using the minimum-time-optimal Hamilton-Jacobi-Bellman framework, which is quite general and can be applied to any spiking neuron model in the conductance-based Hodgkin-Huxley formalism. We also use this methodology to compute a feedback control protocol for optimal spike rate increase. This framework provides a straightforward means of visualizing isochrons, without actually calculating them in the traditional way. Finally, we present an extension of the phase randomizing control scheme that is applied at the population level, to a network of globally coupled neurons that are firing in synchrony. The applied control signal desynchronizes the population in a demand-controlled way. PMID:19911192

Danzl, Per; Hespanha, João; Moehlis, Jeff

2009-12-01

133

How do we process event-based and time-based intentions in the brain? an fMRI study of prospective memory in healthy individuals.  

PubMed

Prospective memory (PM) refers to the ability to remember to do something in the future, either in response to an event (event-based) or after a certain amount of time has elapsed (time-based). While the distinction between event- and time-based PM is widely acknowledged in the literature, little is known about the processes they share and those they do not. This is particularly true concerning their brain substrates, as almost all neuroimaging studies so far have focused on event-based PM. We proposed a functional magnetic resonance imaging paradigm assessing both event-based and time-based PM to 20 healthy young individuals. Analyses revealed that event- and time-based PM both induced activation in the posterior frontal and parietal cortices, and deactivation in the medial rostral prefrontal cortex. In addition, activation more specific to each condition, which may underlie differences in strategic monitoring, was highlighted. Thus, occipital areas were more activated during event-based PM, probably reflecting target-checking, while a network comprising the dorsolateral prefrontal cortex, the cuneus/precuneus and, to a lesser extent, the inferior parietal lobule, superior temporal gyrus, and the cerebellum, was more activated in time-based PM, which may reflect the involvement of time-estimation processes. These results confirm the allocation of attentional resources to the maintenance of intention for event-based and time-based PM, as well as the engagement of distinct mechanisms reflecting the monitoring strategies specific to each condition. Hum Brain Mapp 35:3066-3082, 2014. © 2013 Wiley Periodicals, Inc. PMID:24214215

Gonneaud, Julie; Rauchs, Géraldine; Groussard, Mathilde; Landeau, Brigitte; Mézenge, Florence; de La Sayette, Vincent; Eustache, Francis; Desgranges, Béatrice

2014-07-01

134

An event-based approach to understanding the hydrological impacts of different land uses in semi-arid catchments  

NASA Astrophysics Data System (ADS)

SummaryIn semi-arid catchments around the world re-vegetation is often implemented to reduce quick surface runoff, combat severe soil erosion, restore degraded ecosystem functionality, and, ultimately, improve ecosystem productivity. However, to date, in these water stressed regions, the event-based hydrological impact of different land uses induced by re-vegetation activities is not fully understood at the watershed scale. Traditional hillslope plot experiments and paired watershed experiments have proved difficult to up-scale to a watershed level. In 2006 and 2007, we used broad-crested weirs to measure event streamflow from six catchments within the Caijiachuan watershed (area = 40.1 km 2), located in the Loess Plateau, a semi-arid region in China. The six catchments have different land use compositions with functional combinations of crop, grassland, shrubland, secondary forest, and plantations. Over the same period, event rainfall was measured by a network of rainfall gauges deployed over the study site. We examined the difference in hydrological properties between the catchments using the non-parametric Firedman test, and differentiated the role of each land use in governing watershed hydrology using a numerical analysis technique. Our results showed important differences between the six catchments with respect to event runoff coefficients, normalized peak flow, and event duration. Each land use played a different role in catchment hydrology, as shown by the different mean runoff coefficients ( rc) and mean representative surface flow velocities ( V). Compared to secondary forest ( rc = 0.017 and V = 0.07 m s -1), plantations ( rc = 0.001 and V = 0.18 m s -1) provide a greater potential for increasing shearing force and had a larger impact on runoff reduction. Although shrubland ( rc = 0.096 and V = 0.20 m s -1) and grassland ( rc = 0.127 and V = 0.02 m s -1) have similar magnitude of mean runoff coefficients, grassland seems more capable of trapping sediment due to its lower surface runoff velocity. Cropland ( rc = 0.008 and V = 0.05 m s -1) exerted an important effect on runoff reduction and a moderate effect on flow retardation. We concluded that, to combat severe soil erosion while minimizing water use, re-vegetation in the semi-arid Loess Plateau should not overly, or even solely, rely on plantations. Alternatively, to produce the desired ecosystem functionality, preservation and establishment of grassland during re-vegetation processes should be encouraged, at least, in the early stage of ecological restoration within a "successional re-vegetation" framework.

Wang, Shengping; Zhang, Zhiqiang; McVicar, Tim R.; Zhang, Jianjun; Zhu, Jinzhao; Guo, Junting

2012-01-01

135

The Cognitive Processes Underlying Event-Based Prospective Memory In School Age Children and Young Adults: A Formal Model-Based Study  

PubMed Central

Fifty 7-year-olds (29 female), 53 10-year-olds (29 female), and 36 young adults (19 female), performed a computerized event-based prospective memory task. All three groups differed significantly in prospective memory performance with adults showing the best performance and 7-year-olds the poorest performance. We used a formal multinomial process tree model of event-based prospective memory to decompose age differences in cognitive processes that jointly contribute to prospective memory performance. The formal modeling results demonstrated that adults differed significantly from the 7-year-olds and 10-year-olds on both the prospective component and the retrospective component of the task. The 7-year-olds and 10-year-olds differed only in the ability to recognize prospective memory target events. The prospective memory task imposed a cost to ongoing activities in all three age groups.

Smith, Rebekah E.; Bayen, Ute Johanna; Martin, Claudia

2010-01-01

136

Tracing time in the ocean: a brief review of chronological constraints (60-8 kyr) on North Atlantic marine event-based stratigraphies  

NASA Astrophysics Data System (ADS)

Well-resolved event-based stratigraphies in marine sediments spanning a significant portion of the last glacial period (60-8 kyr) provide a unique opportunity for time-stratigraphic correlation in the North Atlantic region. Here, we review the current methods available to chronologically constrain these event-based stratigraphies, highlighting, in particular, the value of tephrochronology as an independent tool to validate correlations between records. While the INTIMATE protocols (Lowe et al., 2008; Blockley et al., 2011) are equally applicable to marine and terrestrial records, spatially and temporally variable marine radiocarbon reservoir age effects (MREs) provide a challenge to using marine radiocarbon in the former as an independent chronostratigraphic tool. Despite the inherent uncertainties associated with 'tuning', we conclude that the mid-points of the common abrupt warming transitions associated with the well-defined, millennial-scale climate oscillations (the Dansgaard-Oeschger (D/O) cycles) observed in the oxygen isotopes of the Greenland ice cores and North Atlantic sea surface temperature (SST) records currently provide the most robust correlation tie-points from which to derive age control. In this invited INTIMATE special issue article we propose a new protocol for establishing marine event-based chronostratigraphies in the North Atlantic region and focus on areas of chronological potential in palaeoceanographic research.

Austin, William E. N.; Hibbert, Fiona D.

2012-03-01

137

Development of event-based motion correction technique for PET study using list-mode acquisition and optical motion tracking system  

NASA Astrophysics Data System (ADS)

Since recent Positron Emission Tomography (PET) scanner has a high spatial resolution, head motion during brain PET study could cause motion artifact on the image, which might make serious problem in terms of image quality as well as image quantity. Several techniques have been proposed to correct head movement in PET images, for example SPM and AIR software packages. However these techniques are only applicable for correcting the motion between two scans and assume no head movement during scanning. The aim of this study is to develop a technique to correction head motion in event-by-event base during a PET scan using a list-mode data acquisition and optical motion tracking system (POLARIS). This system uses a rebinning procedure whereby the lines of response (LOR) are geometrically transformed according to six-dimensional motion data detected by the POLARIS. A motion-corrected Michelogram was directly composed using the reoriented LOR. In the motion corrected image, the blurring artifact due to the motion was reduced by the present technique. Since the list-mode acquisition stores data as event-by-event base, the present technique makes it possible to correct head movement during PET scanning and has a potential for real-time motion correction of head movement.

Woo, Sang-Keun; Watabe, Hiroshi; Choi, Yong; Kim, Kyeong Min; Park, Chang C.; Fulton, Roger R.; Bloomfield, Peter M.; Iida, Hidehiro

2003-05-01

138

The Semantic Relatedness of Cue-Intention Pairings Influences Event-Based Prospective Memory Failures in Older Adults with HIV Infection  

PubMed Central

HIV infection and aging are each independently associated with prospective memory (ProM) impairment, which increases the risk of poor functional outcomes, including medication adherence. The incidence and prevalence of HIV infection among older adults has increased in recent years, thereby raising questions about the combined effects of these risk factors on ProM. In the present study, 118 participants were classified into four groups on the basis of HIV serostatus and age (i.e., ? 40 years and ? 50 years). Results showed significant additive effects of HIV and aging on event-based ProM, with the greatest deficits evident in the older HIV+ group, even after controlling for other demographic factors and potential medical, and psychiatric confounds. Event-based ProM impairment was particularly apparent in the older HIV+ group on trials for which the retrieval cue and intention were not semantically related. Worse performance on the semantically unrelated cue-intention trials was associated with executive dysfunction, older age, and histories of immunocompromise in the older HIV+ cohort. These data suggest that older HIV-infected adults are significantly less proficient at engaging the strategic encoding and retrieval processes required to a execute a future intention when the cue is unrelated to the intended action, perhaps secondary to greater neuropathological burden in the prefrontostriatal systems critical to optimal ProM functioning.

Woods, Steven Paul; Dawson, Matthew S.; Weber, Erica; Grant, Igor

2009-01-01

139

Adult age differences, response management, and cue focality in event-based prospective memory: a meta-analysis on the role of task order specificity.  

PubMed

The present meta-analysis investigated whether event-based prospective memory (PM) age effects differ by task order specificity. In specified PM tasks, the order of the ongoing and the PM task response is predetermined, which imposes demands on cognitive control to navigate the possible response options. In contrast, unspecified PM tasks do not require responding in a particular order. Based on 57 studies and more than 5,500 younger and older adults, results showed larger PM age effects in specified compared with unspecified PM tasks. Additionally, the effect of task focality on age differences was replicated. Results suggest that both pre- and postretrieval processes independently affect PM age effects. PMID:24041004

Ihle, Andreas; Hering, Alexandra; Mahy, Caitlin E V; Bisiacchi, Patrizia S; Kliegel, Matthias

2013-09-01

140

Patterns of Cortical Thinning in Relation to Event-Based Prospective Memory Performance Three Months after Moderate to Severe Traumatic Brain Injury in Children  

PubMed Central

While event-based prospective memory (EB-PM) tasks are a familiar part of daily life for children, currently no data exists concerning the relation between EB-PM performance and brain volumetrics after traumatic brain injury (TBI). This study investigated EB-PM in children (7 to 17 years) with moderate to severe TBI or orthopedic injuries. Participants performed an EB-PM task and concurrently underwent neuroimaging at three months postinjury. Surface reconstruction and cortical thickness analysis were performed using FreeSurfer software. Cortical thickness was significantly correlated with EB-PM (adjusting for age). Significant thinning in the left (dorsolateral and inferior prefrontal cortex, anterior and posterior cingulate, temporal lobe, fusiform and parahippocampal gyri), and right hemispheres (dorsolateral, inferior, and medial prefrontal cortex, cingulate, and temporal lobe) correlated positively and significantly with EB-PM performance; findings are comparable to those of functional neuroimaging and lesion studies of EB-PM.

McCauley, Stephen R.; Wilde, Elisabeth A.; Merkley, Tricia L.; Schnelle, Kathleen P.; Bigler, Erin D.; Hunter, Jill V.; Vasquez, Ana C.; Levin, Harvey S.

2011-01-01

141

Sexual frequency and planning among at-risk men who have sex with men (MSM) in the US: implications for event-based intermittent pre-exposure prophylaxis (iPrEP)  

PubMed Central

Intermittent dosing of pre-exposure prophylaxis (iPrEP) has potential to decrease costs, improve adherence, and minimize toxicity. Practical event-based dosing of iPrEP requires men who have sex with men (MSM) to be sexually active on fewer than 3 days each week and plan for sexual activity. MSM who may be most suitable for event-based dosing were older, more educated, more frequently used sexual networking websites, and more often reported that their last sexual encounter was not with a committed partner. A substantial proportion of these MSM endorse high-risk sexual activity, and event-based iPrEP may best target this population.

Volk, Jonathan E.; Liu, Albert; Vittinghoff, Eric; Irvin, Risha; Kroboth, Elizabeth; Krakower, Douglas; Mimiaga, Matthew J.; Mayer, Kenneth H.; Sullivan, Patrick S.; Buchbinder, Susan

2012-01-01

142

Task Importance Affects Event-Based Prospective Memory Performance in Adults with HIV-Associated Neurocognitive Disorders and HIV-Infected Young Adults with Problematic Substance Use.  

PubMed

Two experiments were conducted to examine the effects of task importance on event-based prospective memory (PM) in separate samples of adults with HIV-associated neurocognitive disorders (HAND) and HIV-infected young adults with substance use disorders (SUD). All participants completed three conditions of an ongoing lexical decision task: (1) without PM task requirements; (2) with PM task requirements that emphasized the importance of the ongoing task; and (3) with PM task requirements that emphasized the importance of the PM task. In both experiments, all HIV+ groups showed the expected increase in response costs to the ongoing task when the PM task's importance was emphasized. In Experiment 1, individuals with HAND showed significantly lower PM accuracy as compared to HIV+ subjects without HAND when the importance of the ongoing task was emphasized, but improved significantly and no longer differed from HIV+ subjects without HAND when the PM task was emphasized. A similar pattern of findings emerged in Experiment 2, whereby HIV+ young adults with SUD (especially cannabis) showed significant improvements in PM accuracy when the PM task was emphasized. Findings suggest that both HAND and SUD may increase the amount of cognitive attentional resources that need to be allocated to support PM performance in persons living with HIV infection. (JINS, 2014, 21, 1-11). PMID:24834469

Woods, Steven Paul; Doyle, Katie L; Morgan, Erin E; Naar-King, Sylvie; Outlaw, Angulique Y; Nichols, Sharon L; Loft, Shayne

2014-07-01

143

Limited Correlation Between Conventional Pathologist and Automatic Computer-Assisted Quantification of Hepatic Steatosis due to Difference Between Event-Based and Surface-Based Analysis.  

PubMed

Computer-assisted automatic quantification (CAQ) was developed as an alternative method for the diagnosis of hepatic steatosis in order to compensate for observer-dependent bias. Here, we aim to demonstrate that CAQ can provide an accurate and precise result in analysis of fatty content, but that it is inappropriate to validate CAQ by comparison with conventional pathologist estimation (PE). Male rats were fed with a methionine-choline-deficient plus high-fat diet for three days, one week, or two weeks to induce mild, moderate, or severe steatosis. Samples were collected from all liver lobes. Severity of hepatic steatosis was assessed by an experienced pathologist who estimated the percentage of hepatocytes containing lipid droplets. Fatty content was quantified by PE, CAQ, and biochemical analysis (BA). CAQ, PE, and BA can correctly reflect severe fatty change. However, in the case of mild and moderate steatosis, PE could not reflect the true fatty content ( r between PE and BA was <0). The result of CAQ correlated well with that of BA among the various degrees of severity of hepatic steatosis. In conclusion, due to a difference between event-based and surface-based analysis, it is inappropriate to validate the CAQ of hepatic steatosis by comparison with PE. PMID:24235313

Deng, Meihong; Dahmen, Uta; Sun, Jian; Huang, Hai; Sehestedt, Christian; Homeyer, Andre; Schenk, Andrea; Dirsch, Olaf

2014-07-01

144

An event-based approach to validating solar wind speed predictions: High-speed enhancements in the Wang-Sheeley-Arge model  

NASA Astrophysics Data System (ADS)

One of the primary goals of the Center for Integrated Space Weather Modeling (CISM) effort is to assess and improve prediction of the solar wind conditions in near-Earth space, arising from both quasi-steady and transient structures. We compare 8 years of L1 in situ observations to predictions of the solar wind speed made by the Wang-Sheeley-Arge (WSA) empirical model. The mean-square error (MSE) between the observed and model predictions is used to reach a number of useful conclusions: there is no systematic lag in the WSA predictions, the MSE is found to be highest at solar minimum and lowest during the rise to solar maximum, and the optimal lead time for 1 AU solar wind speed predictions is found to be 3 days. However, MSE is shown to frequently be an inadequate "figure of merit" for assessing solar wind speed predictions. A complementary, event-based analysis technique is developed in which high-speed enhancements (HSEs) are systematically selected and associated from observed and model time series. WSA model is validated using comparisons of the number of hit, missed, and false HSEs, along with the timing and speed magnitude errors between the forecasted and observed events. Morphological differences between the different HSE populations are investigated to aid interpretation of the results and improvements to the model. Finally, by defining discrete events in the time series, model predictions from above and below the ecliptic plane can be used to estimate an uncertainty in the predicted HSE arrival times.

Owens, M. J.; Arge, C. N.; Spence, H. E.; Pembroke, A.

2005-12-01

145

Modeling rates of bank erosion in sinuous tidal channel derived from event-based terrestrial lidar surveys in the Mont Saint Michel Bay  

NASA Astrophysics Data System (ADS)

The Mont-Saint-Michel (MSM) bay is characterized by a semi-diurnal regime with a tidal range of 14 meter. Understanding river bank migration of tidal channels in such mega tidal salt marshes requires a precise quantification of the relative contribution of frequent and infrequent bank erosion events to the longer term dynamics. We use terrestrial lidar scanner (TLS) which overcomes the limitations of traditional bank measurement approaches (e.g. aerial photography, GPS measurements) with high resolution and high precision topographic data. We use 30 TLS measurements and traditional data sources to quantify the annual and daily dynamics of bank erosion for a sinuous salt marsh channel near the island of the MSM. We present the results of a 2 years study that begun in September 2010. We compare annual bank retreat with daily surveys focused on spring tides in order to calculate "event-based" volume of bank erosion. For active steep banks, the volume of sediment eroded is computed between 2 set of point cloud that are classified by the CANUPO algorithm to remove vegetation (Brodu and Lague, 2012). A new algorithm allows a direct comparison of point clouds in 3D based on surface normal computation and measurement of mean surface change along the normal direction. On a 5 centimeter resolution grid, the changes between 2 banks point cloud is computed and used to calculate volume of eroded bank. Measured rates of bank retreat varied between no detectable change to 2 m/tide, which correspond roughly to 100 cubic meters/tide. We also document a non-homothetic pattern of bank erosion during spring tides : erosion is focused in narrow zones of the meander and shifts spatially at daily timescales. To relate bank erosion to hydraulic characteristics of the channel, an ADCP was used to measure flow velocity during tides. The measurements highlights two main points that only occurs when tides overcomes the salt marsh: (i) the ebb flow is stronger than flood flow with velocities up to 2.2 m/s and (ii) the maximum ebb velocity (MEV) increase linearly with the maximum tide height. The dominant role of the ebb was also noted during field observations : during the ebb, the flow is focused on a narrow zone of the bank due to rapid bathymetric modifications at daily timescales. This could explain the non-homothetic behavior of bank erosion. The daily volume of eroded bank is only significant when the tide overcome the salt marsh which occurs 10 % of time. From the linear relationship between tide height and MEV, we can relate bank erosion to flow velocity. We show that the eroded volume increases exponentially with the MEV. This new physical model of bank erosion is applied on daily tides records. From Sept 2010 to June 2012, the model succeeds to estimate the volume of bank eroded. However, the model fails to reproduce the dynamics before Sept 2010, which can be explained by a significant change in channel curvature and morphology. The study shows that the combination of TLS and hydrosedimentary measurements can be used to construct 'field' models of tidal channel dynamics. Our data highlights a strong non-linearity between bank erosion, tidal amplitude and ebb flow velocity that results in spring tide events representing 95.7 % of the total erosion for a duration of 10 % of time.

Leroux, J.; Lague, D.

2012-12-01

146

Distributed Architectures for Event-Based Systems  

Microsoft Academic Search

\\u000a Event-driven distributed systems have two important characteristics, which differentiate them from other system types: the\\u000a existence of several software or hardware components that run simultaneously on different inter-networked nodes, and the use\\u000a of events as the main vehicle to organize component intercommunication. Clearly, both attributes influence event-driven distributed\\u000a architectures, which are discussed in this chapter. We start with presenting the

Valentin Cristea; Florin Pop; Ciprian Dobre; Alexandru Costan

147

An Event-Based Architecture Definition Language  

Microsoft Academic Search

This paper discusses general requirements forarchitecture definition languages, and describes the syntaxand semantics of the subset of the Rapide language that is designedto satisfy these requirements. Rapide is a concurrentevent-based simulation language for defining and simulatingthe behavior of system architectures. Rapide is intended formodelling the architectures of concurrent and distributedsystems, both hardware and software. In order to representthe behavior of

David C. Luckham; James Vera

1995-01-01

148

An event based fuzzy temporal logic  

Microsoft Academic Search

A temporal logic is developed to deal with events that are uncertain with regard to their occurrence in a given interval of time. Events are represented as fuzzy sets with the membership function giving the possibility of occurrence of the event in a given interval of time. An axiomatization of the fuzzy event calculus is presented, and several of its

Soumitra Dutta

1988-01-01

149

Modeling of GCR Environment Variations and Interpretation for Human Explorations  

NASA Astrophysics Data System (ADS)

We currently have wealth of data with several short duration Space Shuttle (STS) flights to the low earth orbit (LEO) and long duration International Space Station (ISS) expeditions as well as Shuttle-Mir missions over the past few solar cycles. Assessment of such radiation risk is very important particularly for the anticipated long-term and deep-space human explorations. Recently, we have developed a database of first 500 + human explorers and their space travel logs from space exploration missions during the past four decades. Many have traveled into space for only few days while others have been in space for several months. We present the time-line distribution of the space travelers log along with the time correlated radiation en-vironment changes in to aid in the radiation risk assessment for human explorations. These model calculated results and assessment of radiation exposure helps in our understanding of radiation risk and biological consequences.

Saganti, Premkumar

150

Production of neutrons from interactions of GCR-like particles  

NASA Technical Reports Server (NTRS)

In order to help assess the risk to astronauts due to the long-term exposure to the natural radiation environment in space, an understanding of how the primary radiation field is changed when passing through shielding and tissue materials must be obtained. One important aspect of the change in the primary radiation field after passing through shielding materials is the production of secondary particles from the breakup of the primary. Neutrons are an important component of the secondary particle field due to their relatively high biological weighting factors, and due to their relative abundance, especially behind thick shielding scenarios. Because of the complexity of the problem, the estimation of the risk from exposure to the secondary neutron field must be handled using calculational techniques. However, those calculations will need an extensive set of neutron cross section and thicktarget neutron yield data in order to make an accurate assessment of the risk. In this paper we briefly survey the existing neutron-production data sets that are applicable to the space radiation transport problem, and we point out how neutron production from protons is different than neutron production from heavy ions. We also make comparisons of one the heavy-ion data sets with Boltzmann-Uehling-Uhlenbeck (BUU) calculations.

Heilbronn, L.; Frankel, K.; Holabird, K.; Zeitlin, C.; McMahan, M. A.; Rathbun, W.; Cronqvist, M.; Gong, W.; Madey, R.; Htun, M.; Elaasar, M.; Anderson, B. D.; Baldwin, A. R.; Jiang, J.; Keane, D.; Scott, A.; Shao, Y.; Watson, J. W.; Zhang, W. M.; Galonsky, A.; Ronningen, R.; Zecher, P.; Kruse, J.; Wang, J.; Miller, J. (Principal Investigator)

1998-01-01

151

Profile-Directed Optimization of Event-Based Programs  

Microsoft Academic Search

Events are used as a fundamental abstraction in programs ranging from graphical user interfaces (GUIs) to systems for building customized network protocols. While providing a flexible structuring and execution paradigm, events have the potentially serious drawback of extra execution overhead due to the indirection between modules that raise events and those that handle them. This paper describes an approach to

Mohan Rajagopalan; Saumya K. Debray; Matti A. Hiltunen; Richard D. Schlichting

2002-01-01

152

Stochastic scheduling with event-based dynamic programming  

Microsoft Academic Search

In this paper we apply a new framework for the study of monotonicity in queue- ing systems to stochastic scheduling models. This allows us a unied treatment of many dierent models, among which are multiple and single server models (with and without feedback), discrete and continuous time models, models with controlled and uncontrolled arrivals, etc.

Ger Koole

153

Profile-directed optimization of event-based programs  

Microsoft Academic Search

Events are used as a fundamental abstraction in programs ranging from graphical user interfaces (GUIs) to systems for building customized network protocols. While providing a flexible structuring and execution paradigm, events have the potentially serious drawback of extra execution overhead due to the indirection between modules that raise events and those that handle them. This paper describes an approach to

Mohan Rajagopalan; Saumya K. Debray; Matti A. Hiltunen; Richard D. Schlichting

2002-01-01

154

Stochastic scheduling with event-based dynamic programming  

Microsoft Academic Search

.   In this paper we apply a new framework for the study of monotonicity in queueing systems to stochastic scheduling models.\\u000a This allows us a unified treatment of many different models, among which are multiple and single server models (with and without\\u000a feedback), discrete and continuous time models, models with controlled and uncontrolled arrivals, etc.

Ger Koole

2000-01-01

155

Event-based Program Analysis with DeWiz  

Microsoft Academic Search

Due to the increased complexity of parallel and distributed programs, debugging of them is considered to be the most difficult and time consuming part of the software lifecycle. Tool support is hence a crucial necessity to hide complexity from the user. However, most existing tools seem inadequate as soon as the program under consideration exploits more than a few processors

Ch. Schaubschlaeger; D. Kranzlmueller; Jens Volkert

2003-01-01

156

State and Event-Based Reactive Programming in Shared Dataspaces  

Microsoft Academic Search

The traditional Linda programming style, based on the introductionand consumption of data from a common repository, seemsnot adequate for highly dynamic applications in which it is importantto observe modication of the environment which occur quickly. On theother hand, reactive programming seems more appropriate for this kindof applications. In this paper we consider some approaches recently presentedin the literature for embedding

Nadia Busi; Antony I. T. Rowstron; Gianluigi Zavattaro

2002-01-01

157

A New Data Compression Technique for Event Based Program Traces  

Microsoft Academic Search

The paper presents an innovative solution to the problem of the very huge data sets that are regularly produced by performance\\u000a tracing techniques — especially on HPC programs. It designs an adapted data compression scheme that takes advantage of regularities\\u000a frequently found in program traces. Algorithms to reveal repetition patterns in a programs call structure and run time behavior\\u000a are

Andreas Knüpfer

2003-01-01

158

Event-Based Programming Without Inversion of Control  

Microsoft Academic Search

\\u000a Concurrent programming is indispensable. On the one hand, distributed and mobile environments naturally involve concurrency.\\u000a On the other hand, there is a general trend towards multi-core processors that are capable of running multiple threads in\\u000a parallel.

Philipp Haller; Martin Odersky

2006-01-01

159

An Event Based GUI Programming Toolkit for Embedded System  

Microsoft Academic Search

Due to various differences in hardware architectures of devices in ubiquitous computing systems, portability and platform-independency become the main challenge for graphics programming in system design. In this paper, we propose an adaptive user interface programming toolkit for system design in ubiquitous computing environment. The toolkit leverages an existing system software infrastructure, making the application programming straightforward and platform independent.

Xu Hu; Congfeng Jiang; Wei Zhang; Jilin Zhang; Ritai Yu; Changping Lv

2010-01-01

160

Home Photo Content Modeling for Personalized Event-Based Retrieval  

Microsoft Academic Search

Rapid advances in sensor, storage, processor, and communication technologies let consumers store large digital photo collections. Consumers need effective tools to organize and access photos in a semantically meaningful way. We address the semantic gap between feature-based indexes computed automatically and human query and retrieval preferences.

Joo-hwee Lim; Qi Tian; Philippe Mulhem

2003-01-01

161

Discharges of past flood events based on historical river profiles  

Microsoft Academic Search

This paper presents a case study on the estimation of peak discharges of extreme flood events during the 19th century of the Neckar River located in south-western Germany. It was carried out as part of the BMBF (German Federal Ministry of Education and Research) research project RIMAX (Risk Management of Extreme Flood Events). The discharge estimations were made for the

D. Sudhaus; J. Seidel; K. Bürger; P. Dostal; F. Imbery; H. Mayer; R. Glaser; W. Konold

2008-01-01

162

Game, shot and match: Event-based indexing of tennis  

Microsoft Academic Search

Identifying events in sports video offers great potential for advancing visual sports coaching applications. In this paper, we present our results for detecting key events in a tennis match. Our overall goal is to automatically index a complete tennis match into all the main tennis events, so that a match can be recorded using affordable visual sensing equipment and then

Damien Connaghan; Philip Kelly; Noel E. O'Connor

2011-01-01

163

Event-Based Relaxation of Continuous Disordered Systems  

Microsoft Academic Search

A computational approach is presented to obtain energy-minimized structures in glassy materials. This approach, the activation-relaxation technique (ART), achieves its efficiency by focusing on significant changes in the microscopic structure (events). The application of ART is illustrated with two examples: the structure of amorphous silicon and the structure of Ni80P20, a metallic glass.

G. T. Barkema; Normand Mousseau

1996-01-01

164

Event-based Programming Structures for Multimedia Information Flows  

Microsoft Academic Search

\\u000a In this paper, we propose a programming model based on ‘timed event dissemination’ for structuring a distributed real-time\\u000a multimedia presentation. In this model, event notifications capture program-generated actions and\\/or user-level object accesses\\u000a on a multimedia window. A coherent effect of these actions requires enforcing deadlines on the event processing over prescribed\\u000a time intervals. To meet this requirement, the paper advocates

Kaliappa Nadar Ravindran; Ali Sabbir

2004-01-01

165

Mining Staff Assignment Rules from Event-Based Data  

Microsoft Academic Search

Understanding a process is a basic requirement for improv- ing or reengineering it. Process mining provides methods and techniques for capturing the process behaviour from history data of past executions. Promising control flow mining approaches have been already published. However, organisational aspects have been neglected so far. Especially the link between the process and the organisational structures is less un-

Linh Thao Ly; Stefanie Rinderle; Peter Dadam; Manfred Reichert

2005-01-01

166

Galactic Cosmic Ray Event-Based Risk Model (GERM) Code  

NASA Technical Reports Server (NTRS)

This software describes the transport and energy deposition of the passage of galactic cosmic rays in astronaut tissues during space travel, or heavy ion beams in patients in cancer therapy. Space radiation risk is a probability distribution, and time-dependent biological events must be accounted for physical description of space radiation transport in tissues and cells. A stochastic model can calculate the probability density directly without unverified assumptions about shape of probability density function. The prior art of transport codes calculates the average flux and dose of particles behind spacecraft and tissue shielding. Because of the signaling times for activation and relaxation in the cell and tissue, transport code must describe temporal and microspatial density of functions to correlate DNA and oxidative damage with non-targeted effects of signals, bystander, etc. These are absolutely ignored or impossible in the prior art. The GERM code provides scientists data interpretation of experiments; modeling of beam line, shielding of target samples, and sample holders; and estimation of basic physical and biological outputs of their experiments. For mono-energetic ion beams, basic physical and biological properties are calculated for a selected ion type, such as kinetic energy, mass, charge number, absorbed dose, or fluence. Evaluated quantities are linear energy transfer (LET), range (R), absorption and fragmentation cross-sections, and the probability of nuclear interactions after 1 or 5 cm of water equivalent material. In addition, a set of biophysical properties is evaluated, such as the Poisson distribution for a specified cellular area, cell survival curves, and DNA damage yields per cell. Also, the GERM code calculates the radiation transport of the beam line for either a fixed number of user-specified depths or at multiple positions along the Bragg curve of the particle in a selected material. The GERM code makes the numerical estimates of basic physical and biophysical quantities of high-energy protons and heavy ions that have been studied at the NASA Space Radiation Laboratory (NSRL) for the purpose of simulating space radiation biological effects. In the first option, properties of monoenergetic beams are treated. In the second option, the transport of beams in different materials is treated. Similar biophysical properties as in the first option are evaluated for the primary ion and its secondary particles. Additional properties related to the nuclear fragmentation of the beam are evaluated. The GERM code is a computationally efficient Monte-Carlo heavy-ion-beam model. It includes accurate models of LET, range, residual energy, and straggling, and the quantum multiple scattering fragmentation (QMSGRG) nuclear database.

Cucinotta, Francis A.; Plante, Ianik; Ponomarev, Artem L.; Kim, Myung-Hee Y.

2013-01-01

167

Tsunami Warning Criteria for Cascadia events based on Tsunami models  

NASA Astrophysics Data System (ADS)

Initial tsunami warning, advisory, and watch zones for potential Cascadia earthquakes have been revised based on maximum expected threat for tsunamis generated by earthquakes in this region. Presently, alert zones are initially based on travel time for earthquakes greater than magnitude 7.8 with all areas less than three hours away from the source being put into a tsunami warning. The impact of this change is to reduce the length of coastline which is immediately put it into a warning status. Tsunami Warning Centers often delineate initial tsunami alert zones based on pre-set criteria dependent on earthquake magnitude, location, depth, and tsunami travel time. In many cases, this approach can lead to over-warning. Over the last several years, the West Coast/Alaska Tsunami Warning Center (WCATWC) has attempted to refine the amount of coastline immediately placed in a warning status based on maximum expected threat instead of travel time. Tsunami forecast models used to predict impacts during events (for example, Alaska Tsunami Forecast Model (ATFM), Short-term Inundation Forecasting for Tsunamis (SIFT), and Rapid Inundation Forecasting of Tsunamis (RIFT)) can also be used a-priori to delineate zones at-risk for specified source zones. forecast models have proven reasonably accurate during recent events. For the Cascadia Subduction zone, several rupture scenarios ranging from magnitude 7.9 to 9.2, were computed. Forecasted wave heights at various points are then used to set the initial Warning/Watch/Advisory regions. This procedure is more efficient than a blanket warning - or a refined warning based on travel times - as appropriate threat levels are assigned based on expected impact. For example, after a magnitude 8.7 earthquake in the southern Cascadia Subduction zone, southern and most of central California can be left out of the warning zone and placed in an advisory, as none of this region contains expected impacts in the warning threshold (tsunami amplitude over 1m). Under previous criteria, these zones would have been placed in a warning. Several examples are shown which help refine criteria used by the Tsunami Warning Center during hypothetical Cascadia events.

Huang, P. Y.; Nyland, D. L.; Knight, W.; Gately, K.; Hale, D.; Urban, G.; Waddell, J.; Carrick, J.; Popham, C.; Bahng, B.; Kim, Y.; Burgy, M.; Langley, S.; Preller, C. C.; Whitmore, P.

2013-12-01

168

Event-based Trust Framework Model in Wireless Sensor Networks  

Microsoft Academic Search

The security of wireless sensor networks is ever more important nowadays. Most of the proposed security protocols in wireless sensor networks are based on authentication and encryption. But all of them only address part of the problem of security in wireless sensor networks. Recently, the use of reputation and trust systems has become an important secure mechanism in wireless sensor

Haiguang Chen; Huafeng Wu; Jinchu Hu; Chuanshan Gao

2008-01-01

169

MCD for detection of event-based landslides  

NASA Astrophysics Data System (ADS)

Landslides play an important role in the landscape evolution of mountainous terrain. They also present a socioeconomic problem in terms of risk for people and properties. Landslide inventory maps are not available for many areas affected by slope instabilities, resulting in a lack of primary information for the comprehension of the phenomenon, evaluation of relative landslide statistics, and civil protection operations on large scales. Traditional methods for the preparation of landslide inventory maps are based on the geomorphological interpretation of stereoscopic aerial photography and field surveys. These methods are expensive and time consuming. The exploitation of new remote sensing data, in particular very high resolution (VHR) satellite images, and new dedicated methods present an alternative to the traditional methods and are at the forefront of modern landslide research. Recent studies have showed the possibility to produce accurate landslide maps, reducing the time and resources required for their compilation and systematic update. This paper presents the Multiple Change Detection (MCD) technique, a new method that has shown promising results in landslide mapping. Through supervised or unsupervised classifiers, MCD combines different algorithms of change detection metrics, such as change in Normalized Differential Vegetation Index, spectral angle, principal component analysis, and independent component analysis, and applies them to a multi-temporal set of VHR satellite images to distinguish new landslides from stable areas. MCD has been applied with success in different geographical areas and with different satellite images, suggesting it is a reliable and robust technique. The technique can distinguish old from new landslides and capture runout features. Results of these case studies will be presented in the conference. Also to be presented are new developments of MCD involving the introduction of a priori information on landslide susceptibility within a Bayesian framework.

Mondini, A. C.; Chang, K.; Guzzetti, F.

2011-12-01

170

Variability in the GCR Count Rate as Measured by the CRaTER Instrument on LRO  

Microsoft Academic Search

The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) is currently orbiting the Moon onboard NASA's Lunar Reconnaissance Orbiter (LRO). CRaTER is composed of a stack of 3 pairs of axially-aligned solid-state Silicon detectors which surround 2 sections of Tissue Equivalent Plastic. Particles that have enough energy to penetrate the outer skin of the instrument (about 10 MeV for

A. W. Case; H. E. Spence; M. J. Golightly; J. C. Kasper; J. B. Blake; J. E. Mazur; L. W. Townsend

2009-01-01

171

Benchmark problem for IAEA coordinated research program (CRP-3) on GCR afterheat removal. 1.  

National Technical Information Service (NTIS)

In this report, detailed data which are necessary for the benchmark analysis of International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP-3) on 'Heat Transport and Afterheat Removal for Gas-cooled Reactors under Accident Conditions' are ...

S. Takada Y. Shiina Y. Inagaki M. Hishida Y. Sudo

1995-01-01

172

Event-based programming models for monitoring of distributed information systems  

Microsoft Academic Search

The paper deals with providing a specification methodology to enable flexible monitoring in large scale distributed information systems (DIS). The goal is to allow the monitoring of compliance to properties deemed as critical for functioning of a DIS. Since information attacks due to external intrusion and\\/or component failures often manifest as deviations from critical behaviors expected of a DIS, a

K. Rnvindran; Jun Wu

2005-01-01

173

Structural results for the control of queueing systems using event-based dynamic programming  

Microsoft Academic Search

In this paper we study monotonicity results for optimal policies of various queueing and resource sharing models. The standard\\u000a approach is to propagate, for each specific model, certain properties of the dynamic programming value function. We propose\\u000a a unified treatment of these models by concentrating on the events and the form of the value function instead of on the value

Ger Koole

1998-01-01

174

Scala Actors: Unifying thread-based and event-based programming  

Microsoft Academic Search

There is an impedance mismatch between message-passing concurrency and virtual ma- chines, such as the JVM. VMs usually map their threads to heavyweight OS processes. Without a lightweight process abstraction, users are often forced to write parts of concur- rent applications in an event-driven style which obscures control flow, and increases the burden on the programmer. In this paper we

Philipp Haller; Martin Odersky

2009-01-01

175

Altitude extension of auroral potential structures by event-based and statistical studies  

NASA Astrophysics Data System (ADS)

Lots of observations below about 13000 km altitude favour the U-shaped potential model above auroral arcs. Recent observational findings above 20000 km indicate, however, that the U-shaped potential related to stable auroral arcs does not usually extend to that altitude. To resolve the dilemma, we have suggested an O-shaped potential model. Here we show how an O-shaped potential can form self-consistently by assuming plasma waves that energise ˜50-400 eV electrons in the parallel direction. The obtained "cooperative" model invokes both waves and O-shaped potential structures in a nontrivial manner to produce inverted-V spectra and auroral arcs, and it is compatible with satellite observations at both low and high altitude.

Janhunen, P.; Olsson, A.; Laakso, H.

2001-01-01

176

Real-Time and Event-Based Prediction Capabilities of Modern Space Science Models  

NASA Astrophysics Data System (ADS)

The Community Coordinated Modeling Center (CCMC) is a US inter-agency activity aiming at research in support of the generation of advanced space weather models. As one of its main functions, the CCMC provides to researchers the use of space science models, even if they are not model owners themselves. The second CCMC activity is to support Space Weather forecasting at national Space Weather Forecasting Centers. This second activity involves model evaluations, model transitions to operations, and the development of draft Space Weather Forecasting tools. This presentation will focus on the latter element. Specifically, we will analyze current forecasting potential of state-of-the-art models. These capabilities will be demonstrated by an example, and we will comment on readiness for operations.

Chulaki, A.; Hesse, M.; Rastaetter, L.; Kuznetsova, M.; MacNeice, P.

2008-12-01

177

Internet-based Software Engineering Enables and Requires Event-Based Management Tools  

Microsoft Academic Search

Distributed software engineering (DSE) eorts oer dicult challenges to those whoneed to monitor and manage the overall process. Without the capability to know whatis happening in the process, the risk of failing to produce a quality product on scheduleincreases greatly. With Internet-based DSE, the opportunity exists to capture data fromthe process at relatively low cost, since so much of the

Jonathan E. Cook

2000-01-01

178

Event-Based Interaction Management for Composite E-Services in eFlow  

Microsoft Academic Search

The Web is rapidly becoming the platform through which many companies deliver e-services to businesses and individual customers. E-Services are typically delivered in their primitive forms, called basic services. However, today's business environment creates the opportunity for providing value-added, integrated services, delivered by composing existing e-services, possibly offered by different providers.

Fabio Casati; Ming-chien Shan

2002-01-01

179

Loss Modeling with a Data-Driven Approach in Event-Based Rainfall-Runoff Analysis  

NASA Astrophysics Data System (ADS)

Mathematical models require the estimation of rainfall abstractions for accurate predictions of runoff. Although loss models such as the constant loss and exponential loss models are commonly used, these methods are based on simplified assumptions of the physical process. A new approach based on the data driven paradigm to estimate rainfall abstractions is proposed in this paper. The proposed data driven model, based on the artificial neural network (ANN) does not make any assumptions on the loss behavior. The estimated discharge from a physically-based model, obtained from the kinematic wave (KW) model assuming zero losses, was used as the only input to the ANN. The output is the measured discharge. Thus, the ANN functions as a black-box loss model. Two sets of data were analyzed for this study. The first dataset consists of rainfall and runoff data, measured from an artificial catchment (area = 25 m2) comprising two overland planes (slope = 11%), 25m long, transversely inclined towards a rectangular channel (slope = 2%) which conveyed the flow, recorded using calibrated weigh tanks, to the outlet. Two rain gauges, each placed 6.25 m from either ends of the channel, were used to record rainfall. Data for six storm events over the period between October 2002 and December 2002 were analyzed. The second dataset was obtained from the Upper Bukit Timah catchment (area = 6.4 km2) instrumented with two rain gauges and a flow measuring station. A total of six events recorded between November 1987 and July 1988 were selected for this study. The runoff predicted by the ANN was compared with the measured runoff. In addition, results from KW models developed for both the catchments were used as a benchmark. The KW models were calibrated assuming the loss rate for an average event for each of the datasets. The results from both the ANN and KW models agreed well with the runoff measured from the artificial catchment. The KW model is expected to perform well since the catchment is completely impervious and the losses are small. Thus, the good agreement of results between the ANN with the KW model results demonstrates the applicability of the ANN model in modeling the loss rate. Comparing the modeled runoff with the measured runoff for the Upper Bukit Timah catchment, it was found that the KW model was not able to produce the runoff from the catchment accurately due to the improper prescription of the loss rate. This is because the loss rate varies over a wide range of values in a real catchment and using the loss rate for an average event did not provide truly representative values for the catchment. Although the same dataset was used in the training of the ANN model, the ANN model was able to produce hydrographs with significantly higher Nash-Sutcliffe coefficients compared to the KW model. This analysis demonstrates that the ANN model is better able to model the highly variable loss rate during storm events, especially if the data used for calibration is limited. ACKNOWLEDGEMENT Funding received from the DHI-NTU Water & Environment Research Centre and Education Hub is gratefully acknowledged.

Chua, L. H. C.

2012-04-01

180

Coupling urban event-based and catchment continuous modelling for combined sewer overflow river impact assessment  

Microsoft Academic Search

Since Water Framework Directive (WFD) was passed in year 2000, the conservation of water bodies in the EU must be understood in a completely different way. Regarding to combined sewer overflows (CSOs) from urban drainage networks, the WFD implies that we cannot accept CSOs because of their intrinsic features, but they must be assessed for their impact on the receiving

I. Andrés-Doménech; J. C. Múnera; F. Francés; J. B. Marco

2010-01-01

181

Coupling urban event-based and catchment continuous modelling for combined sewer overflow river impact assessment  

Microsoft Academic Search

Since the Water Framework Directive (WFD) was passed in year 2000, the protection of water bodies in the EU must be understood in a completely different way. Regarding to combined sewer overflows (CSOs) from urban drainage networks, the WFD implies that CSOs cannot be accepted because of their intrinsic features, but must be assessed for their impact on the receiving

I. Andrés-Doménech; J. C. Múnera; F. Francés; J. B. Marco

2010-01-01

182

Event based uncertainty assessment in urban drainage modelling, applying the GLUE methodology  

NASA Astrophysics Data System (ADS)

SummaryIn the present paper an uncertainty analysis on an application of the commercial urban drainage model MOUSE is conducted. Applying the Generalized Likelihood Uncertainty Estimation (GLUE) methodology the model is conditioned on observation time series from two flow gauges as well as the occurrence of combined sewer overflow. The GLUE methodology is used to test different conceptual setups in order to determine if one model setup gives a better goodness of fit conditional on the observations than the other. Moreover, different methodological investigations of GLUE are conducted in order to test if the uncertainty analysis is unambiguous. It is shown that the GLUE methodology is very applicable in uncertainty analysis of this application of an urban drainage model, although it was shown to be quite difficult to get good fits of the whole time series.

Thorndahl, S.; Beven, K. J.; Jensen, J. B.; Schaarup-Jensen, K.

2008-08-01

183

An Event-Based Wireless Navigation and Healthcare System for Group Recreational Cycling  

Microsoft Academic Search

Recreational cycling is a popular leisure activity in which the cyclist mostly is involved for a whole day at a time. This makes safety and comfort some of the most important factors to be attended to, especially when cycling in group. Group recreational cycling (GRC) is a new kind of tourism involving a courier and a number of tourists. Beside

Kun-Ming Yu; Jiayi Zhou; Cheng-Yan Yu; Jian-Yuan Liu; Chi-Chung Lee; Hsin-Wen Chang; Hung-Nien Hsieh

2009-01-01

184

Southern Hemisphere Biogeography Inferred by Event-Based Models: Plant versus Animal Patterns  

Microsoft Academic Search

The Southern Hemisphere has traditionally been considered as having a fundamentally vicariant history. The common trans-Pacific disjunctions are usually explained by the sequential breakup of the supercontinent Gondwana during the last 165 million years, causing successive division of an ancestral biota. However, recent biogeographic studies, based on molecular estimates and more accurate paleogeographic reconstructions, indicate that dispersal may have been

ISABEL SANMARTÍN; FREDRIK RONQUIST

2004-01-01

185

Irreversible event-based model for thermal emission of electrons from isolated traps  

NASA Astrophysics Data System (ADS)

In spite of the irreversible nature of macroscopic processes, our understanding of the fundamental physical phenomena remains limited to reversible models (the Loschmidt's paradox). We propose a direct irreversible model for the probability per unit time that an electron will be emitted from an isolated trap. This resolves a number of problems, including (1) the dubious link between emission measurements and the parameters of the independent capture process and (2) the elusive meaning of the degeneracy factor in the equilibrium Fermi-Dirac distribution.

Dimitrijev, Sima

2009-05-01

186

Forecast of Tourism Emergency Events Based on Quantum Immune Clone Algorithm  

Microsoft Academic Search

The development of tourism industry has become so fast today. However, there are unexpected events occur in the developing process. Based on the tourism information in recent years, this paper combined quantum computing with immune clone algorithm and applied them to the data mining of emergency events of tourism information, deducing the links between emergency rules. Finally through the simulative

Junping Du; You Tian

2007-01-01

187

Event-based categorical sequential analyses of the medical interview: a review.  

PubMed

When the doctor-patient interaction is viewed as a series of utterances, the temporal position of utterances becomes a central information in understanding the nature of interaction. Important concepts are interdependence and serial dependence which account for the fact that two partners influence each other in their talk and that each partner influences him/herself. Lag sequential analysis studies the associations between doctor and patient utterances in a two-way contingency table (lag one sequences) and is used for exploratory purposes. Long-linear modelling, based on multi-way contingency tables, is used as an extension of lag-sequential analysis to study longer sequences. Markov chains test sequences in terms of processes with the aim to find predictive models and require a theory driven approach. Pattern recognition aims to discover regularities in the temporal evolution of the utterance sequences. Theory driven applications analyse manifest patterns in terms of their conditional probability distribution while empirically driven applications are used to detect "hidden" patterns. These different approaches to sequential data can be regarded as complementary tools to describe the doctor patient consultations at various levels of complexity. PMID:12916447

Mazzi, Maria Angela; Del Piccolo, Lidia; Zimmermann, Christa

2003-01-01

188

AH IDDEN MARKOV MODEL FOR METRIC AND EVENT-BASED DATA  

Microsoft Academic Search

The question of data representation is central to any data analysis problem. Ideally, the representation should faithfully describe the domain to be analyzed and in addition, the model used should be able to pro- cess such a representation. In practice, however, the modeler must often compromise how the problem is de- scribed, since the class of possible representations is con-

Jaakko Hollmen; Volker Tresp

2000-01-01

189

Issues in Informal Education: Event-Based Science Communication Involving Planetaria and the Internet  

NASA Technical Reports Server (NTRS)

For the last several years the Science Directorate at Marshall Space Flight Center has carried out a diverse program of Internet-based science communication. The program includes extended stories about NASA science, a curriculum resource for teachers tied to national education standards, on-line activities for students, and webcasts of real-time events. The focus of sharing real-time science related events has been to involve and excite students and the public about science. Events have involved meteor showers, solar eclipses, natural very low frequency radio emissions, and amateur balloon flights. In some cases broadcasts accommodate active feedback and questions from Internet participants. Panel participation will be used to communicate the problems and lessons learned from these activities over the last three years.

Adams, Mitzi L.; Gallagher, D. L.; Whitt, A.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

190

Event-Based GUI Testing and Reliability Assessment Techniques -- An Experimental Insight and Preliminary Results  

Microsoft Academic Search

It is widely accepted that graphical user interfaces (GUIs) highly affect—positive or negative—the quality and reliability of human-machine systems. In spite of this fact, quantitative assessment of the reliability of GUIs is a relatively young research field. Existing software reliability assessment techniques attempt to statistically describe the software testing process and to determine and thus predict the reliability of the

Fevzi Belli; Mutlu Beyazit; Nevin Güler

2011-01-01

191

A study of preservice elementary teachers enrolled in a discrepant-event-based physical science class  

NASA Astrophysics Data System (ADS)

This research evaluated the POWERFUL IDEAS IN PHYSICAL SCIENCE (PIiPS) curriculum model used to develop a physical science course taken by preservice elementary teachers. The focus was on the evaluation of discrepant events used to induce conceptual change in relation to students' ideas concerning heat, temperature, and specific heat. Both quantitative and qualitative methodologies were used for the analysis. Data was collected during the 1998 Fall semester using two classes of physical science for elementary school teachers. The traditionally taught class served as the control group and the class using the PIiPS curriculum model was the experimental group. The PIiPS curriculum model was evaluated quantitatively for its influence on students' attitude toward science, anxiety towards teaching science, self efficacy toward teaching science, and content knowledge. An analysis of covariance was performed on the quantitative data to test for significant differences between the means of the posttests for the control and experimental groups while controlling for pretest. It was found that there were no significant differences between the means of the control and experimental groups with respect to changes in their attitude toward science, anxiety toward teaching science and self efficacy toward teaching science. A significant difference between the means of the content examination was found (F(1,28) = 14.202 and p = 0.001), however, the result is questionable. The heat and energy module was the target for qualitative scrutiny. Coding for discrepant events was adapted from Appleton's 1996 work on student's responses to discrepant event science lessons. The following qualitative questions were posed for the investigation: (1) what were the ideas of the preservice elementary students prior to entering the classroom regarding heat and energy, (2) how effective were the discrepant events as presented in the PIiPS heat and energy module, and (3) how much does the "risk taking factor" associated with not telling the students the answer right away, affect the learning of the material. It was found that preservice elementary teachers harbor similar preconceptions as the general population according to the literature. The discrepant events used in this module of the PIiPS curriculum model met with varied results. It appeared that those students who had not successfully confronted their preconceptions were less likely to accept the new concepts that were to be developed using the discrepant events. Lastly, students had shown great improvement in content understanding and developed the ability to ask deep and probing questions.

Lilly, James Edward

192

IBM smart surveillance system (S3): a open and extensible framework for event based surveillance  

Microsoft Academic Search

As smart surveillance technology becomes a critical component in security infrastructures, the system architecture assumes a critical importance. This paper considers the example of smart surveillance in an airport environment. We start with a threat model for airports and use this to derive the security requirements. These requirements are used to motivate an open-standards based architecture for surveillance. We discuss

Chiao-fe Shu; Arun Hampapur; Max Lu; Lisa M. G. Brown; Jonathan Connell; Andrew W. Senior; Yingli Tian

2005-01-01

193

The value of manual, event-based sediment sampling in local-scale sediment budget studies  

NASA Astrophysics Data System (ADS)

Many contemporary sediment-budget studies lack two things: a first-hand understanding of the behavior of the system, and high-frequency data during storm events. In a study designed to understand sediment source areas, we have approach these deficiencies through manual sampling, almost exclusively during storm events. Manual sampling leads to better understanding. Frequently, the researcher finds oneself standing in streams observing phenomenon that contradict their a priori, desktop, or textbook-based perception of system behaviour. The case study we present reflects this in its observations of very high percolation rates, differing levels of land-stream connectivity under different sized events, and landowner intervention in water and sediment flux. In drier regions with episodic rainfall, event sampling is essential. During one season, we sampled 13 sites in a 316 km2 watershed about 50 times each. The sampling times were targeted to observe the start of the rising stage, many points immediately around the hydrograph peak, once or twice during the falling stage, and once after the return to pre-event conditions. The same number of samples spread over the year at regular intervals would lead to a grossly inaccurate representation of the system by the data. For example, event sampling permitted a reasonably accurate characterization of total annual load at each site. A simple, static model was then used to apportion total loads to different land use sources, and in-channel sources.

Casagrande, J.; Watson, F.; Hager, J.; Anderson, T.; Newman, W.; Kozlowski, D.; Rocha, A.; Cole, W.; Larson, J.; Feikert, B.; Oakins, A.; Pierce, L.; Curry, B.

2001-12-01

194

Event-Based Plausibility Immediately Influences On-Line Language Comprehension  

ERIC Educational Resources Information Center

In some theories of sentence comprehension, linguistically relevant lexical knowledge, such as selectional restrictions, is privileged in terms of the time-course of its access and influence. We examined whether event knowledge computed by combining multiple concepts can rapidly influence language understanding even in the absence of selectional…

Matsuki, Kazunaga; Chow, Tracy; Hare, Mary; Elman, Jeffrey L.; Scheepers, Christoph; McRae, Ken

2011-01-01

195

An event-based neural network architecture with an asynchronous programmable synaptic memory.  

PubMed

We present a hybrid analog/digital very large scale integration (VLSI) implementation of a spiking neural network with programmable synaptic weights. The synaptic weight values are stored in an asynchronous Static Random Access Memory (SRAM) module, which is interfaced to a fast current-mode event-driven DAC for producing synaptic currents with the appropriate amplitude values. These currents are further integrated by current-mode integrator synapses to produce biophysically realistic temporal dynamics. The synapse output currents are then integrated by compact and efficient integrate and fire silicon neuron circuits with spike-frequency adaptation and adjustable refractory period and spike-reset voltage settings. The fabricated chip comprises a total of 32 × 32 SRAM cells, 4 × 32 synapse circuits and 32 × 1 silicon neurons. It acts as a transceiver, receiving asynchronous events in input, performing neural computation with hybrid analog/digital circuits on the input spikes, and eventually producing digital asynchronous events in output. Input, output, and synaptic weight values are transmitted to/from the chip using a common communication protocol based on the Address Event Representation (AER). Using this representation it is possible to interface the device to a workstation or a micro-controller and explore the effect of different types of Spike-Timing Dependent Plasticity (STDP) learning algorithms for updating the synaptic weights values in the SRAM module. We present experimental results demonstrating the correct operation of all the circuits present on the chip. PMID:24681923

Moradi, Saber; Indiveri, Giacomo

2014-02-01

196

A Mobile Robots Experimental Environment with Event-Based Wireless Communication  

PubMed Central

An experimental platform to communicate between a set of mobile robots through a wireless network has been developed. The mobile robots get their position through a camera which performs as sensor. The video images are processed in a PC and a Waspmote card sends the corresponding position to each robot using the ZigBee standard. A distributed control algorithm based on event-triggered communications has been designed and implemented to bring the robots into the desired formation. Each robot communicates to its neighbors only at event times. Furthermore, a simulation tool has been developed to design and perform experiments with the system. An example of usage is presented.

Guinaldo, Maria; Fabregas, Ernesto; Farias, Gonzalo; Dormido-Canto, Sebastian; Chaos, Dictino; Sanchez, Jose; Dormido, Sebastian

2013-01-01

197

Classification of extratropical cyclogenesis events based on a set of precursors  

NASA Astrophysics Data System (ADS)

Many studies indicate a large variability of the relevant physical processes (so-called precursors) responsible for cyclogenesis. In this study, potential precursors for cyclogenesis are systematically and comprehensibly investigated on a statistical basis. For this reason, cyclones are objectively identified during the time period 2000-2011 in the ERA-interim dataset and then tracked along their life cycle. The starting points of these tracks are considered as the points of cyclogenesis. In the environment of these cyclogenesis locations a set of about 30 potential precursors is determined. The set includes the following parameters: (a) the surface conditions and fluxes (e.g., sensible and latent heat fluxes, sea surface temperature); (b) characteristic conditions in the troposphere (e.g., vertically integrated water vapor, amplitude of low-level potential vorticity); (c) measures of baroclinic and convective stability (e.g., horizontal temperature gradients, convective available potential energy, Eady growth rate); and (d) flow patterns and forcings from upper-tropospheric and stratospheric levels (e.g., jet streams and streaks, potential vorticity anomalies). In addition to simple Eulerian characterisations, more advanced diagnostic approaches are applied: Lagrangian backward trajectories, averaged time since oceanic moisture uptake of involved low-level air parcels, and layerwise quasi-geostrophic forcing for vertical motion. In the phase space of these potential precursors - determined for a multitude of cyclones and suitably normalized - a principal component analysis is performed. The first two principal components are used subsequently for the separation of the cyclogenesis events in nine classes. Composites of each class are constructed in order to represent the averaged spatial pattern of the precursors. This statistical approach reveals that the most important separating mechanisms are upper-level forcing and moist processes. They are to a large extent represented by the low-level and upper-level potential vorticity. Weak (strong) upper-level forcing is associated with a zonal (meridional) flow pattern. The classification of Petterssen and Smebye is reproduced, if enhanced moisture values are present. But also other physical mechanisms can be detected (e.g., diabatic Rossby waves). The classification approach is additionally applied to a selection of cyclones, which caused high-impact weather during their lifecycle.

Graf, Michael; Sprenger, Michael; Wernli, Heini

2014-05-01

198

An events based algorithm for distributing concurrent tasks on multi-core architectures  

NASA Astrophysics Data System (ADS)

In this paper, a programming model is presented which enables scalable parallel performance on multi-core shared memory architectures. The model has been developed for application to a wide range of numerical simulation problems. Such problems involve time stepping or iteration algorithms where synchronization of multiple threads of execution is required. It is shown that traditional approaches to parallelism including message passing and scatter-gather can be improved upon in terms of speed-up and memory management. Using spatial decomposition to create orthogonal computational tasks, a new task management algorithm called H-Dispatch is developed. This algorithm makes efficient use of memory resources by limiting the need for garbage collection and takes optimal advantage of multiple cores by employing a "hungry" pull strategy. The technique is demonstrated on a simple finite difference solver and results are compared to traditional MPI and scatter-gather approaches. The H-Dispatch approach achieves near linear speed-up with results for efficiency of 85% on a 24-core machine. It is noted that the H-Dispatch algorithm is quite general and can be applied to a wide class of computational tasks on heterogeneous architectures involving multi-core and GPGPU hardware.

Holmes, David W.; Williams, John R.; Tilke, Peter

2010-02-01

199

Generic-Events Architecture: Integrating Real-World Aspects in Event-Based Systems  

Microsoft Academic Search

In a future networked physical world, a myriad of smart sensors and actuators assess and control aspects of their environments\\u000a and autonomously act in response to it. To a large extent, such systems operate proactively and independently of direct human\\u000a control. They include computer hardware and software parts mixed with mechanical devices. Besides the regular computer communication\\u000a channels, they also

Antonio Casimiro; Jörg Kaiser; Paulo Veríssimo

2006-01-01

200

A mobile robots experimental environment with event-based wireless communication.  

PubMed

An experimental platform to communicate between a set of mobile robots through a wireless network has been developed. The mobile robots get their position through a camera which performs as sensor. The video images are processed in a PC and a Waspmote card sends the corresponding position to each robot using the ZigBee standard. A distributed control algorithm based on event-triggered communications has been designed and implemented to bring the robots into the desired formation. Each robot communicates to its neighbors only at event times. Furthermore, a simulation tool has been developed to design and perform experiments with the system. An example of usage is presented. PMID:23881139

Guinaldo, María; Fábregas, Ernesto; Farias, Gonzalo; Dormido-Canto, Sebastián; Chaos, Dictino; Sánchez, José; Dormido, Sebastián

2013-01-01

201

Estimating the frequency of extremely energetic solar events, based on solar, stellar, lunar, and terrestrial records  

NASA Astrophysics Data System (ADS)

The most powerful explosions on the Sun - in the form of bright flares, intense storms of solar energetic particles (SEPs), and fast coronal mass ejections (CMEs) - drive the most severe space-weather storms. Proxy records of flare energies based on SEPs in principle may offer the longest time base to study infrequent large events. We conclude that one suggested proxy, nitrate concentrations in polar ice cores, does not map reliably to SEP events. Concentrations of select radionuclides measured in natural archives may prove useful in extending the time interval of direct observations up to ten millennia, but as their calibration to solar flare fluences depends on multiple poorly known properties and processes, these proxies cannot presently be used to help determine the flare energy frequency distribution. Being thus limited to the use of direct flare observations, we evaluate the probabilities of large-energy solar events by combining solar flare observations with an ensemble of stellar flare observations. We conclude that solar flare energies form a relatively smooth distribution from small events to large flares, while flares on magnetically active, young Sun-like stars have energies and frequencies markedly in excess of strong solar flares, even after an empirical scaling with the mean coronal activity level of these stars. In order to empirically quantify the frequency of uncommonly large solar flares extensive surveys of stars of near-solar age need to be obtained, such as is feasible with the Kepler satellite. Because the likelihood of flares larger than approximately X30 remains empirically unconstrained, we present indirect arguments, based on records of sunspots and on statistical arguments, that solar flares in the past four centuries have likely not substantially exceeded the level of the largest flares observed in the space era, and that there is at most about a 10% chance of a flare larger than about X30 in the next 30 years.

Schrijver, C. J.; Beer, J.; Baltensperger, U.; Cliver, E. W.; Güdel, M.; Hudson, H. S.; McCracken, K. G.; Osten, R. A.; Peter, T.; Soderblom, D. R.; Usoskin, I. G.; Wolff, E. W.

2012-08-01

202

Frequency analysis of extreme events based on precipitation station data over southeastern Brazil  

NASA Astrophysics Data System (ADS)

The southeastern coast (SE) of Brazil is among the most densely populated areas of eastern South America with population largely concentrated in urban centers. Due to complex terrain and chaotic urbanization, this region is subject to a variety of natural disasters, including but not limited to floods and landslides that frequently occur during the austral summer (September to March). The South American Monsoon System (SAMS) and the South Atlantic Convergence zone (SACZ) are the most important climatic features that affect precipitation regimes in SE Brazil during the Austral summer. Previous studies have shown an overall increasing trend in daily precipitation and consequently in extreme events in SE Brazil. Future scenarios of climate change seem to indicate that SAMS daily precipitation will likely continue to increase throughout the 21st century. However, the rainfall response to the predicted warming is heterogeneous, and there is large uncertainty in the projected rainfall change and corresponding regional-to-local impacts. Some observational studies have demonstrated a positive trend in the frequency of extreme events in particular locations. Nevertheless, these analyses either focus on one single station or investigate relatively short periods. This study further investigates interannual to multiannual variations and changes in the frequency of daily extreme precipitation events in SE Brazil using long time series from a set of rain gauges stations. The analyzed rain gauge stations are located along the coastal area of SE Brazil (between 18°S and 25°S) and have at least 74 years of daily data, with less than 5% missing. The period of analysis varies slightly from station to station, but roughly all stations have data between 1930 and 2012. The analysis of the frequency of extreme events is based on the Peaks-over-Threshold (POT) approach, which follows a General Pareto Distribution (GPD), under the independent identically distributed assumption. Furthermore, these approaches can be applied to non-stationary series, as they are based on time dependent thresholds composed by the extreme quantiles of the daily rainfall. The presence of annual trend is also tested using a non-parametric Mann-Kendall test. In addition, the stations encompass the area with large influence of the SACZ. This study also investigates stations located at the margin of the climatological position of the SACZ, in order to contrast the importance of the convergence zone for trends in extreme precipitation.

Zilli, M. T.; Carvalho, L. V.

2013-12-01

203

Infrastructure for Smart Cities: The Killer Application for Event-Based Computing  

Microsoft Academic Search

Smart cities are part of the Ambient Intelligence vision that foresees the vanishing of computational devices into the fabric of society and the ubiquitous availability of intelligent services in support of our daily lives. In this vision we should not be burdened by conscious manipulation of devices and ever more powerful but also complex interfaces. Instead, devices should be able

Alejandro P. Buchmann

2007-01-01

204

Performance predictions affect attentional processes of event-based prospective memory.  

PubMed

To investigate whether making performance predictions affects prospective memory (PM) processing, we asked one group of participants to predict their performance in a PM task embedded in an ongoing task and compared their performance with a control group that made no predictions. A third group gave not only PM predictions but also ongoing-task predictions. Exclusive PM predictions resulted in slower ongoing-task responding both in a nonfocal (Experiment 1) and in a focal (Experiment 2) PM task. Only in the nonfocal task was the additional slowing accompanied by improved PM performance. Even in the nonfocal task, however, was the correlation between ongoing-task speed and PM performance reduced after predictions, suggesting that the slowing was not completely functional for PM. Prediction-induced changes could be avoided by asking participants to additionally predict their performance in the ongoing task. In sum, the present findings substantiate a role of metamemory for attention-allocation strategies of PM. PMID:23703025

Rummel, Jan; Kuhlmann, Beatrice G; Touron, Dayna R

2013-09-01

205

Task Interference in Time-Based, Event-Based, and Dual Intention Prospective Memory Conditions  

ERIC Educational Resources Information Center

Forming the intention to complete an activity later is the standard definition of a prospective memory task. Recently, a debate has arisen concerning the degree to which near-term intentions usurp resources away from other ongoing activities. In four experiments the authors tested how much interference was caused by holding a variety of different…

Hicks, Jason L.; Marsh, Richard L.; Cook, Gabriel I.

2005-01-01

206

Effect of age on event-based and time-based prospective memory  

Microsoft Academic Search

The magnitude of age differences on event- and time-based prospective memory tasks was investigated in 2 experiments. Participants performed a working memory task and were also required to perform either an event- or time-based prospective action. Control participants performed either the working memory task only or the prospective memory task only. Results yielded age differences on both prospective tasks. The

Denise C. Park; Christopher Hertzog; Daniel P. Kidder; Roger W. Morrell

1997-01-01

207

Task interference in time-based, event-based, and dual intention prospective memory conditions  

Microsoft Academic Search

Forming the intention to complete an activity later is the standard definition of a prospective memory task. Recently, a debate has arisen concerning the degree to which near-term intentions usurp resources away from other ongoing activities. In four experiments the authors tested how much interference was caused by holding a variety of different intentions. In all but one case, possessing

Jason L. Hicks; Richard L. Marsh; Gabriel I. Cook

2005-01-01

208

Decreased event-based prospective memory functioning in individuals with Parkinson's disease.  

PubMed

The study was aimed at investigating the contribution of retrospective memory to prospective memory (PM) functioning in people with Parkinson's disease (PD). Twenty patients with PD without dementia and 20 normal controls were recruited. In the PM procedure, sequences of words were presented; in the inter-sequence delay, participants had to repeat sequence in the same or reverse order (ongoing task). At the occurrence of a target word, participants had to press a button on the keyboard (PM response). To evaluate the contribution of retrospective memory to PM performance, we manipulated the retrospective memory load of the target words (i.e., one vs. four words). The results show that patients with PD were poorer than controls in all PM conditions (p < .01). The memory load did not modulate differentially the PM performance of individuals in the two groups. Moreover, in PD patients, the ability to retrieve the target words in the episodic memory task was associated, at a lesser extent than in healthy controls, with the ability to activate the prospective intention at the occurrence of a target word. Our findings confirm PM decline in patients with PD without dementia. This flaw cannot be entirely explained by decreased retrospective memory. Altered self-retrieval processes might explain reduced PM performance of these individuals. This is a very relevant finding in the perspective of cognitive therapeutic intervention on PM that, in patients with PD, could be focused on mechanisms other than retrospective memory ones. PMID:23809543

Costa, Alberto; Peppe, Antonella; Caltagirone, Carlo; Carlesimo, Giovanni A

2013-09-01

209

Rain Characteristics and Large-Scale Environment Associated with Extreme Precipitation Events Based on TRMM Observations  

NASA Astrophysics Data System (ADS)

This study utilizes the Precipitation Feature (PF) database developed at the University of Utah to analyze extreme precipitation events from 13-year TRMM observations. Characteristics of instantaneous extreme volumetric PFs, their geophysical distributions and diurnal variations are examined and compared to those of intermediate and small systems. It is found that the instantaneous PF exhibits much larger scale range than daily gridded precipitation, with those at top 1% of PFs two orders of magnitude greater than the medium PF but contributing to over 50% of instantaneous rainfall. The study shows that extreme PFs are significantly larger, deeper and colder than the lower 80% of the PFs. NCEP reanalysis shows a systematic increase in surface moist static energy (MSE) with larger PFs but convective available potential energy (CAPE) levels off for extremely large systems. Mid-level relative humidity and total precipitable water increase consistently for increasingly heavy precipitation events, suggesting a potential role of increasing moisture in a warming climate in producing extreme precipitation events.

Zhou, Y.; Lau, W. K.

2012-12-01

210

Event based neutron activation spectroscopy and analysis algorithm using MLE and metaheuristics  

NASA Astrophysics Data System (ADS)

Techniques used in neutron activation analysis are often dependent on the experimental setup. In the context of developing a portable and high efficiency detection array, good energy resolution and half-life discrimination are difficult to obtain with traditional methods [1] given the logistic and financial constraints. An approach different from that of spectrum addition and standard spectroscopy analysis [2] was needed. The use of multiple detectors prompts the need for a flexible storage of acquisition data to enable sophisticated post processing of information. Analogously to what is done in heavy ion physics, gamma detection counts are stored as two-dimensional events. This enables post-selection of energies and time frames without the need to modify the experimental setup. This method of storage also permits the use of more complex analysis tools. Given the nature of the problem at hand, a light and efficient analysis code had to be devised. A thorough understanding of the physical and statistical processes [3] involved was used to create a statistical model. Maximum likelihood estimation was combined with metaheuristics to produce a sophisticated curve-fitting algorithm. Simulated and experimental data were fed into the analysis code prompting positive results in terms of half-life discrimination, peak identification and noise reduction. The code was also adapted to other fields of research such as heavy ion identification of the quasi-target (QT) and quasi-particle (QP). The approach used seems to be able to translate well into other fields of research.

Wallace, Barton

2014-03-01

211

Classification of Traffic Events based on the Spatio-Temporal MRF Model and the Bayesian Network  

Microsoft Academic Search

In order to support safe and efficient driving, it is important to classify the behaviors of vehicles and to understand what is going on the traffic situations. For that purpose, our system employed a vision sensor rather than spot sensors because of its rich information. We then have developed a dedicated vehicle tracking algorithm based on the Spatio-Temporal MRF model

Shunsuke KAMIJO Masao SAKAUCHI

2002-01-01

212

An Early Warning System for Hypoglycemic/Hyperglycemic Events Based on Fusion of Adaptive Prediction Models  

PubMed Central

Introduction Early warning of future hypoglycemic and hyperglycemic events can improve the safety of type 1 diabetes mellitus (T1DM) patients. The aim of this study is to design and evaluate a hypoglycemia/hyperglycemia early warning system (EWS) for T1DM patients under sensor-augmented pump (SAP) therapy. Methods The EWS is based on the combination of data-driven online adaptive prediction models and a warning algorithm. Three modeling approaches have been investigated: (i) autoregressive (ARX) models, (ii) auto-regressive with an output correction module (cARX) models, and (iii) recurrent neural network (RNN) models. The warning algorithm performs postprocessing of the models? outputs and issues alerts if upcoming hypoglycemic/hyperglycemic events are detected. Fusion of the cARX and RNN models, due to their complementary prediction performances, resulted in the hybrid autoregressive with an output correction module/recurrent neural network (cARN)-based EWS. Results The EWS was evaluated on 23 T1DM patients under SAP therapy. The ARX-based system achieved hypoglycemic (hyperglycemic) event prediction with median values of accuracy of 100.0% (100.0%), detection time of 10.0 (8.0) min, and daily false alarms of 0.7 (0.5). The respective values for the cARX-based system were 100.0% (100.0%), 17.5 (14.8) min, and 1.5 (1.3) and, for the RNN-based system, were 100.0% (92.0%), 8.4 (7.0) min, and 0.1 (0.2). The hybrid cARN-based EWS presented outperforming results with 100.0% (100.0%) prediction accuracy, detection 16.7 (14.7) min in advance, and 0.8 (0.8) daily false alarms. Conclusion Combined use of cARX and RNN models for the development of an EWS outperformed the single use of each model, achieving accurate and prompt event prediction with few false alarms, thus providing increased safety and comfort.

Daskalaki, Elena; N?rgaard, Kirsten; Zuger, Thomas; Prountzou, Aikaterini; Diem, Peter; Mougiakakou, Stavroula

2013-01-01

213

An event-based model of braided river system aquifers heterogeneity based on Multiple Points Statistics  

NASA Astrophysics Data System (ADS)

Braided-rivers are common in mountainous regions like the Swiss Alps. These dynamic systems generate highly heterogeneous deposits and form an important part of alluvial aquifers which are tapped for agriculture and drinking water supply. In this presentation, we propose to integrate large scale and high resolution LIDAR data in a pseudo genetic approach embedding Multiple Points Statistics (MPS) to model the heterogeneity of such aquifers. A way to build 3D sedimentary models is to use descriptive methods, which translate data into conceptual facies models but do not offer uncertainty quantification. Another possibility is the use of stochastic models but most of them do not include strong geological knowledge and their degree of realism can be rather weak. Another approach is to use process-based methods. In this work, we imitate the processes occurring during flood events, by building successive topographies with the Direct Sampling (DS) multiple point statistics algorithm. Each successive topography is conditioned by the previous one. All those steps are constrained by a series of LIDAR data sets allowing to train the algorithm. This is different from classical MPS models, since we do not directly use MPS to model the lithofacies directly, but instead to simulate the processes that lead to the heterogeneity in order to ensure that higher statistics that can be inferred from field data are accurately reproduced. The use of the DS is motivated by the fact that it an MPS technique allowing to co-simulate continuous variables. It is easy to condition to field data and offers a high degree of realism in the simulations. The underlying erosion-deposition process leaves some records of each event in the form of remaining layers, which are populated with facies of different granulometry, according to some predefined rules function of the geobody's shape and dimensions. Input parameters allow controlling the aggradation/degradation intensity.

Renard, P.; Pirot, G.

2012-12-01

214

Event-Based Modeling of Driver Yielding Behavior to Pedestrians at Two-Lane Roundabout Approaches  

PubMed Central

Unlike other types of controlled intersections, drivers do not always comply with the “yield to pedestrian” sign at the roundabouts. This paper aims to identify the contributing factors affecting the likelihood of driver yielding to pedestrians at two-lane roundabouts. It further models the likelihood of driver yielding based on these factors using logistic regression. The models have been applied to 1150 controlled pedestrian crossings at entry and exit legs of two-lane approaches of six roundabouts across the country. The logistic regression models developed support prior research that the likelihood of driver yielding at the entry leg of roundabouts is higher than at the exit. Drivers tend to yield to pedestrians carrying a white cane more often than to sighted pedestrians. Drivers traveling in the far lane, relative to pedestrian location, have a lower probability of yielding to a pedestrian. As the speed increases the probability of driver yielding decreases. At the exit leg of the roundabout, drivers turning right from the adjacent lane have a lower propensity of yielding than drivers coming from other directions. The findings of this paper further suggest that although there has been much debate on pedestrian right-of-way laws and distinction between pedestrian waiting positions (in the street versus at the curb), this factor does not have a significant impact on driver yielding rate. The logistic regression models also quantify the effect of each of these factors on propensity of driver yielding. The models include variables which are specific to each study location and explain the impact size of each study location on probability of yielding. The models generated in this research will be useful to transportation professionals and researchers interested in understanding the factors that impact driver yielding at modern roundabouts. The results of the research can be used to isolate factors that may increase yielding (such as lower roundabout approach speeds), and can feasibly be incorporated into microsimulation algorithms to model driver yielding at roundabouts.

Salamati, Katayoun; Schroeder, Bastian J.; Geruschat, Duane R.; Rouphail, Nagui M.

2013-01-01

215

Issues in Informal Education: Event-Based Science Communication Involving Planetaria and the Internet  

NASA Technical Reports Server (NTRS)

For the past four years the Science Directorate at Marshall Space Flight Center has carried out a diverse program of science communication through the web resources on the Internet. The program includes extended stories about NAS.4 science, a curriculum resource for teachers tied to national education standards, on-line activities for students, and webcasts of real-time events. Events have involved meteor showers, solar eclipses, natural very low frequency radio emissions, and amateur balloon flights. In some cases broadcasts accommodate active feedback and questions from Internet participants. We give here, examples of events, problems, and lessons learned from these activities.

Adams, M.; Gallagher, D. L.; Whitt, A.; Six, N. Frank (Technical Monitor)

2002-01-01

216

Models and Monte Carlo simulations of GCR and SPE organ doses with different shielding, based on the FLUKA code coupled with anthropomorphic phantoms  

Microsoft Academic Search

Astronauts' exposure to space radiation is of major concern for long-term missions, especially for those in deep space such as a possible mission to Mars. Shielding optimization is therefore a crucial issue, and simulations based on radiation transport codes coupled with anthropomorphic model phantoms can be of great help. In this work, carried out with the FLUKA MC code and

F. Ballarini

2004-01-01

217

Demantelement des reacteurs a uranium naturel-graphite-gaz: corrosion des structures internes des caissons pendant leur conservation. (GCR dismantling: corrosion of vessel internals during decay storage).  

National Technical Information Service (NTIS)

Gas-cooled reactor decommissioning confronts EDF with the problem of the corrosion resistance of vessel internals over a decay storage period fixed at 50 years. The layer of magnetite previously formed in the C0(sub 2) should protect structural steelwork ...

J. M. Gras

1991-01-01

218

Simulation of the ATIC-2 Silicon Matrix for Protons and Helium GCR Primaries at 0.3, 10, and 25 TeV/Nucleon  

NASA Technical Reports Server (NTRS)

The energy deposition distribution for protons and helium galactic cosmic ray primaries at 0.3, 10, and 25 TeV/nucleon in the ATIC-2 silicon matrix detector are simulated with GEANT4. The GEANT3 geometrical model of ATIC developed by the University of Maryland was combined with a GEANT4 application developed for the Deep Space Test Bed (DSTB) detector package. The new code included relatively minor modifications to completely describe the ATIC materials and a more detailed model of the Silicon Matrix detector. For this analysis all particles were started as a unidirectional beam at a single point near the center of the Silicon Matrix front surface. The point was selected such that each primary passed through at least two of the overlapping silicon pixels.

Watts, J.; Adams, J. H.; Bashindzhagyan, G.; Batkov, K. E.; Chang, J.; Christl, M.; Fazely, A. R.; Ganel, O.; Gunasingha R. M.; Guzik, T. G.

2005-01-01

219

The natural oscillation of two types of ENSO events based on analyses of CMIP5 model control runs  

NASA Astrophysics Data System (ADS)

The eastern- and central-Pacific El Niño-Southern Oscillation (EP- and CP-ENSO) have been found to be dominant in the tropical Pacific Ocean, and are characterized by interannual and decadal oscillation, respectively. In the present study, we defined the EP- and CP-ENSO modes by singular value decomposition (SVD) between SST and sea level pressure (SLP) anomalous fields. We evaluated the natural features of these two types of ENSO modes as simulated by the pre-industrial control runs of 20 models involved in phase five of the Coupled Model Intercomparison Project (CMIP5). The results suggested that all the models show good skill in simulating the SST and SLP anomaly dipolar structures for the EP-ENSO mode, but only 12 exhibit good performance in simulating the tripolar CP-ENSO modes. Wavelet analysis suggested that the ensemble principal components in these 12 models exhibit an interannual and multi-decadal oscillation related to the EP- and CP-ENSO, respectively. Since there are no changes in external forcing in the pre-industrial control runs, such a result implies that the decadal oscillation of CP-ENSO is possibly a result of natural climate variability rather than external forcing.

Xu, Kang; Su, Jingzhi; Zhu, Congwen

2014-07-01

220

Detection of water-quality contamination events based on multi-sensor fusion using an extented Dempster-Shafer method  

NASA Astrophysics Data System (ADS)

This study presents a method for detecting contamination events of sources of drinking water based on the Dempster-Shafer (D-S) evidence theory. The detection method has the purpose of protecting water supply systems against accidental and intentional contamination events. This purpose is achieved by first predicting future water-quality parameters using an autoregressive (AR) model. The AR model predicts future water-quality parameters using recent measurements of these parameters made with automated (on-line) water-quality sensors. Next, a probabilistic method assigns probabilities to the time series of residuals formed by comparing predicted water-quality parameters with threshold values. Finally, the D-S fusion method searches for anomalous probabilities of the residuals and uses the result of that search to determine whether the current water quality is normal (that is, free of pollution) or contaminated. The D-S fusion method is extended and improved in this paper by weighted averaging of water-contamination evidence and by the analysis of the persistence of anomalous probabilities of water-quality parameters. The extended D-S fusion method makes determinations that have a high probability of being correct concerning whether or not a source of drinking water has been contaminated. This paper's method for detecting water-contamination events was tested with water-quality time series from automated (on-line) water quality sensors. In addition, a small-scale, experimental, water-pipe network was tested to detect water-contamination events. The two tests demonstrated that the extended D-S fusion method achieves a low false alarm rate and high probabilities of detecting water contamination events.

Hou, Dibo; He, Huimei; Huang, Pingjie; Zhang, Guangxin; Loaiciga, Hugo

2013-05-01

221

Stable Isotope Ratios of Hydrogen and Oxygen in Event-based Precipitation at Linze, the Hexi Corridor, Northwestern China  

NASA Astrophysics Data System (ADS)

The stable isotope ratios of single precipitation events were investigated during the period June 2008 to August 2012 at Linze, which is located in the Hexi Corridor and adjacent to the northern Tibetan Plateau. The local meteoric water line (LMWL) for Linze, ?2H = 8.270?18O + 6.215 (r2 = 0.954, n = 45), was derived using amount-weighted monthly average ?2H and ?18O values to be consistent with International Atomic Energy Agency (IAEA) established practice. The correlation equation between ?2H and ?18O values from individual samples was found to be ?2H = 8.053?18O + 2.535 (r2 = 0.944, n = 165), which is different from the LMWL, exhibiting lower slope value and intercept value. The ?18O temperature dependences at Linze was 0.514‰/oC, smaller than the global values based on monthly average temperature. No marked amount effect was found in this study. These isotopic characteristics of precipitation may be attributed to the incorporation of inland recycled moisture into clouds and secondary evaporation during precipitations. Clear seasonal trends were identified in both oxygen isotope ratios and the deuterium-excess, and these were ascribed to the intraannual variation of moisture transport to this region. The deuterium-excess values were high in summer and autumn, when moisture was derived from westerly transport. The deuterium-excess values were low during the cold and dry periods, when moisture originated from the humid ocean surface. This finding reveals that the air mass from the westerly transport dominates the precipitation in the Hexi Corridor, while the southwest monsoon contributes little to the annual precipitation because it is blocked by Tibetan Plateau. Our data also suggest that the moisture derived from local evapotranspiration may contribute greatly to the precipitation.

Sun, Z.; Ma, R.; Zhou, A.

2013-12-01

222

Robotic goalie with 3 ms reaction time at 4% CPU load using event-based dynamic vision sensor.  

PubMed

Conventional vision-based robotic systems that must operate quickly require high video frame rates and consequently high computational costs. Visual response latencies are lower-bound by the frame period, e.g., 20 ms for 50 Hz frame rate. This paper shows how an asynchronous neuromorphic dynamic vision sensor (DVS) silicon retina is used to build a fast self-calibrating robotic goalie, which offers high update rates and low latency at low CPU load. Independent and asynchronous per pixel illumination change events from the DVS signify moving objects and are used in software to track multiple balls. Motor actions to block the most "threatening" ball are based on measured ball positions and velocities. The goalie also sees its single-axis goalie arm and calibrates the motor output map during idle periods so that it can plan open-loop arm movements to desired visual locations. Blocking capability is about 80% for balls shot from 1 m from the goal even with the fastest-shots, and approaches 100% accuracy when the ball does not beat the limits of the servo motor to move the arm to the necessary position in time. Running with standard USB buses under a standard preemptive multitasking operating system (Windows), the goalie robot achieves median update rates of 550 Hz, with latencies of 2.2 ± 2 ms from ball movement to motor command at a peak CPU load of less than 4%. Practical observations and measurements of USB device latency are provided. PMID:24311999

Delbruck, Tobi; Lang, Manuel

2013-01-01

223

Benefit of merging precipitation from rain gauges and radar for event based and continuous simulations of floods  

NASA Astrophysics Data System (ADS)

Several merging methods combining radar or satellite data with gauge data have been developed in order to make available better input data for distributed hydrological modelling. However, in many studies the performance of the merging methods is only validated using precipitation data, while the benefit of using improved precipitation estimation for hydrological modelling is not evaluated. In this study the objective was to test the hypothesis that better rainfall data according to precipitation cross-validation should enable a better simulation of floods. For interpolation different methods of varying complexity were chosen: the nearest neighbour method as the simplest one, ordinary kriging as standard geostatistical approach and kriging with external drift (KED) as a more sophisticated geostatistical method merging point observations with weather radar data. The investigations were conducted on the basis of 12 flood events caused by precipitation with different characteristics as well as continuous simulations over a period of four years. For hydrological modelling the raster-based runoff and water balance simulation model WaSiM-ETH with the topmodel approach was chosen. Hydrological modelling was conducted on an hourly time step for three mesoscale catchments with diverse physiographic characteristics and rainfall network configurations located on the foothills of the Harz Mountains. According to precipitation cross-validation the most complex interpolation method KED using radar rainfall intensities as additional information was the best interpolation method by far. Regarding the simulation of floods though, a general improvement for all cases could not be detected. Only for specific events and time periods, always additionally dependent on the catchment, advantages could be achieved.

Verworn, A.; Haberlandt, U.

2012-04-01

224

Disentangling executive functions and memory processes in event?based prospective remembering after brain damage: A neuropsychological study  

Microsoft Academic Search

Successful prospective remembering (PR) comprises at least two components: one retrospective component that refers to the encoding and retrieval of the content of the intention and a second prospective component that involves the retrieval of the intended action at the appropriate moment. Whereas the retrospective component is very similar to memory skills like learning and retention of new information, the

Ute A. Kopp

2003-01-01

225

Controls of event-based pesticide leaching in natural soils: A systematic study based on replicated field scale irrigation experiments  

NASA Astrophysics Data System (ADS)

We performed a series of three replicated field scale irrigation experiments.We examined the link between irrigation, flow paths, and pesticide transport.Irrigation amount and soil moisture threshold control solute transport.We observed remobilization of stored pesticides occurring together with soil water mobilization.

Klaus, Julian; Zehe, Erwin; Elsner, Martin; Palm, Juliane; Schneider, Dorothee; Schröder, Boris; Steinbeiss, Sibylle; van Schaik, Loes; West, Stephanie

226

JERK, an event-based Kinetic Monte Carlo model to predict microstructure evolution of materials under irradiation  

Microsoft Academic Search

JERK is a Kinetic Monte Carlo model which aims at describing the evolution of materials under irradiation over large time and length scales. The evolution is calculated by collecting only those events which actually modify the objects making up the microstructure (defect clusters, various complexes, dislocations), by sampling their probability of occurrence, deciding in view of the chosen delays whether

J. Dalla Torre; J.-L. Bocquet; N. V. Doan; E. Adam; A. Barbu

2005-01-01

227

Monitoring of event based mobilization of hydrophobic pollutants in rivers: Calibration of turbidity as a proxy for particle facilitated transport  

NASA Astrophysics Data System (ADS)

Transport of many pollutants in rivers is coupled to transport of suspended particles which is typically enhanced during events such as floods, snow melts etc. As the amount of total suspended solids (TSS) in rivers can be monitored by turbidity measurements this may be used as a proxy for the total concentration of particle associated pollutants in rivers such as polycyclic aromatic hydrocarbons (PAHs), PCBs, etc. and several heavy metals. On-line turbidity measurements (e.g. by optical backscattering sensors) then allow for an assessment of particle and pollutant flux dynamics. In this study, pronounced flood and thus turbidity events were sampled at high temporal resolution in three contrasting catchments in Southwest Germany (Rivers Ammer, Goldersbach, Steinlach) as well as in the River Neckar. Samples were analyzed for turbidity, the total amount of PAH and total suspended solids (TSS) in water. Additionally, the grain size distributions of suspended solids were determined. Discharge and turbidity were measured on-line at gauging stations in three of the catchments. Results showed that turbidity and TSS were linearly correlated over an extended turbidity range up to 2000 NTU for the flood samples (i.e. independent on grain size). This also holds for total PAH concentrations which can be reasonably well predicted based on the turbidity measurements and TSS versus PAH relationships - even for very high turbidity or TSS values (> 2000 NTU or mg l-1, respectively). From these linear regressions concentrations of PAHs on suspended particles were obtained which varied by catchment. The values comprise a robust measure of the average sediment quality in a river network and may be correlated to the degree of urbanization represented by the number of inhabitants per total flux of suspended particles. Based on long-term on-line turbidity measurements mass flow rates of particle bound pollutants over time could be calculated. Results showed that by far the largest amount of pollutant loads occur at relative high turbidities > 100 NTU which are observed only during very short time periods. Therefore it is of particular importance not to miss these pronounced but rare events.

Rügner, Hermann; Schwientek, Marc; Grathwohl, Peter

2014-05-01

228

Varying the importance of a prospective memory task: Differential effects across time - and event-based prospective memory  

Microsoft Academic Search

Only few studies have addressed the issue of task importance in prospective memory. Most of them, but not all, have shown that perceived task importance does improve prospective memory performance. However, there is little understanding of (1) the conditions under which importance of the prospective memory task makes a difference in performance and (2) the mechanisms by which perceived task

Matthias Kliegel; Mike Martin; Mark A. McDaniel; Gilles O. Einstein

2001-01-01

229

The Cost of Remembering to Remember in Event-Based Prospective Memory: Investigating the Capacity Demands of Delayed Intention Performance  

Microsoft Academic Search

Prospective memory tasks are often accomplished during the performance of other activities. Despite the dual-task nature of prospective memory, little attention has been paid to how successful prospective memory performance affects ongoing activities. In the first 2 experiments, participants performing an embedded prospective memory task had longer response times on nonprospective memory target trials of a lexical decision task than

Rebekah E. Smith

2003-01-01

230

Proposal for an Interference Experiment to Test the Applicability of Quantum Theory to Event-Based Processes  

NASA Astrophysics Data System (ADS)

We analyze a single-particle Mach--Zehnder interferometer experiment in which the path length of one arm may change (randomly or systematically) according to the value of an external two-valued variable x, for each passage of a particle through the interferometer. Quantum theory predicts an interference pattern that is independent of the sequence of the values of x. On the other hand, corpuscular models that reproduce the results of quantum optics experiments carried out to date show a reduced visibility and a shift of the interference pattern depending on the details of the sequence of the values of x. The proposed experiment will show that: (1) it can be described by quantum theory, and thus not by the current corpuscular models, or (2) it cannot be described by quantum theory but can be described by the corpuscular models or variations thereof, or (3) it can neither be described by quantum theory nor by corpuscular models. Therefore, the proposed experiment can be used to determine the extent to which quantum theory provides a description of observed events beyond the usual statistical level.

Michielsen, Kristel; Lippert, Thomas; Richter, Marcus; Barbara, Bernard; Miyashita, Seiji; Raedt, Hans De

2012-03-01

231

Scheduling of loading and unloading of crude oil in a refinery using event-based discrete time formulation  

Microsoft Academic Search

One of the most critical activities in a refinery is the scheduling of loading and unloading of crude oil. Better analysis of this activity gives rise to better use of a system's resources, as well as control of the entire supply chain. It is important that the crude oil is loaded and unloaded contiguously, primarily for security reasons (e.g. possibility

Georgios K. D. Saharidis; Michel Minoux; Yves Dallery

2009-01-01

232

Monitoring of event-based mobilization of hydrophobic pollutants in rivers: Calibration of turbidity as a proxy for particle facilitated transport in field and laboratory.  

PubMed

Transport of many pollutants in rivers is coupled to mobilization of suspended particles which typically occurs during floods. Since the amount of total suspended solids (TSS) in rivers can be monitored by turbidity measurements this may be used as a proxy for the total concentration of particle associated pollutants such as PAHs, PCBs, etc. and several heavy metals. Online turbidity measurements (e.g. by optical backscattering sensors) would then also allow for an assessment of particle and pollutant flux dynamics if once calibrated against TSS and total pollutant concentrations for a given catchment. In this study, distinct flood and thus turbidity events were sampled at high temporal resolution in three contrasting sub-catchments of the River Neckar in Southwest Germany (Ammer, Goldersbach, Steinlach) as well as in the River Neckar itself and investigated for the total amount of PAHs and TSS in water; turbidity (NTU) and grain size distributions of suspended solids were determined as well. Laboratory experiments were performed with natural river bed sediments from different locations (Ammer) to investigate PAH concentrations, TSS and turbidity during sedimentation of suspended particles under controlled conditions (yielding smaller and smaller suspended particles and TSS with time). Laboratory and field results agreed very well and showed that turbidity and TSS were linearly correlated over an extended turbidity range up to 2000NTU for the field samples and up to 8000NTU in lab experiments. This also holds for total PAH concentrations which can be reasonably well predicted based on turbidity measurements and TSS vs. PAHs relationships - even for high turbidity values observed during flood events (>2000NTU). Total PAH concentrations on suspended solids were independent of grain size of suspended particles. This implies that for the rivers investigated the sorption capacity of particles did not change significantly during the observed events. PMID:24858216

Rügner, Hermann; Schwientek, Marc; Egner, Marius; Grathwohl, Peter

2014-08-15

233

An empirical-stochastic, event-based program for simulating inflow from a tributary network: Framework and application to the Sacramento River basin, California  

Microsoft Academic Search

A stochastic streamflow program was developed to simulate inflow to a large river from a network of gauged tributaries. The program uses historical streamflow data from major tributary gauges near their confluence with the main stem and combines them stochastically to represent spatial and temporal patterns in flood events. It incorporates seasonality, event basis, and correlation in flood occurrence and

Michael Bliss Singer; Thomas Dunne

2004-01-01

234

Raceway design and simulation system (RDSS): An event-based program to simulate the day-to-day operations of multiple-tank raceways  

Microsoft Academic Search

A software program, called Raceway Design and Simulation System (RDSS), has been built using Visual Basic for Applications in Microsoft® Excel. The purpose of the software is to allow users to manage their raceways more efficiently by providing a tool to simulate the operation of an existing raceway or to predict conditions in a raceway under a wide variety of

Yin-Han Wang; Richard Turton; Ken Semmens; Tatiana Borisova

2008-01-01

235

What controls the isotopic composition of the African monsoon precipitation? Insights from event-based precipitation collected during the 2006 AMMA field campaign  

NASA Astrophysics Data System (ADS)

The stable isotopic composition of the tropical precipitation constitutes a useful tool for paleoclimate reconstructions and to better constrain the water cycle. To better understand what controls the isotopic composition of tropical precipitation, we analyze the ? 18O and deuterium-excess of the precipitation of individual events collected in the Niamey area (Niger) during the monsoon season, as part of the 2006 AMMA field campaign. During the monsoon onset, the abrupt increase of convective activity over the Sahel is associated with an abrupt change in the isotopic composition. Before the onset, when convective activity is scarce, the rain composition records the intensity and the organization of individual convective systems. After the onset, on the contrary, it records a regional-scale intra-seasonal variability over the Sahel, by integrating convective activity both spatially and temporally over the previous days.

Risi, Camille; Bony, Sandrine; Vimeux, Francoise; Descroix, Luc; Ibrahim, Boubacar; Lebreton, Eric; Mamadou, Ibrahim; Sultan, Benjamin

2008-12-01

236

A criterion for identifying Asian dust events based on Al concentration data collected from northern Taiwan between 2002 and early 2007  

Microsoft Academic Search

We attempted to identify Asian dust (AD) events between February 2002 and February 2007 in northern Taiwan using aerosol Al measurements. We subsequently used the results to propose a criterion for defining AD events. A total of 30 AD events were detected based on Al spiking concentrations, and these occurred frequently in 2002 and 2006. The dust plumes that were

Shih-Chieh Hsu; Shaw Chen Liu; Yi-Tang Huang; Shih-Chun Candice Lung; Fujung Tsai; Jien-Yi Tu; Shuh-Ji Kao

2008-01-01

237

Event-based measurement of boundary-layer winds and topographic effects with a small unmanned aircraft system (sUas)  

NASA Astrophysics Data System (ADS)

Numerical models are invaluable tools for developing and testing hypotheses about interactions and feedbacks between wind and topography. However, field-based measurements are equally important for building and enhancing confidence in model output. Several field methods are available, including conventional approaches using tall masts equipped with an array of anemometers, as well as weather balloons, but few methods are able to match the level of detail available in model simulations of topographically-modified windflow. Here we propose an alternative method that may enhance numerical models. The method involves a small unmanned aircraft system (sUas) equipped with a meteorological sensor payload. The sUas is a two blade helicopter that weighs 5.5 kg, and has a length of 1.32 m. We designed a simple measurement and control system using an Arduino micro-controller, which acquired measurements at pre-defined coordinates autonomously. The entire survey was pre-configured and uploaded to the aircraft, effectively avoiding the need for manual aircraft operation and data collection. We collected raw measurements at each waypoint, yielding a point cloud of windspeed data. During test flights the sUas was able to maintain a stable position (± 0.6 m vertical and horizontal) in wind speeds up to 50 km/h. We used the raw data to map the wind speed-up ratio relative to a reference anemometer. Although it would be preferable to acquire continuous measurements at each waypoint, the sUas method only provides a snapshot of wind at each location. However, despite this limitation, the sUas does fill a void in terms of spatial measurements within the boundary layer. It may be possible to enhance this method in the future through deployment of sUas swarms that measure wind concurrently at many locations. Furthermore, other sensors can be deployed on sUas for measuring aeolian processes such as dust.

Riddell, K.; Hugenholtz, C.

2012-12-01

238

Linguistic scope-based and biological event-based speculation and negation annotations in the BioScope and Genia Event corpora  

PubMed Central

Background The treatment of negation and hedging in natural language processing has received much interest recently, especially in the biomedical domain. However, open access corpora annotated for negation and/or speculation are hardly available for training and testing applications, and even if they are, they sometimes follow different design principles. In this paper, the annotation principles of the two largest corpora containing annotation for negation and speculation – BioScope and Genia Event – are compared. BioScope marks linguistic cues and their scopes for negation and hedging while in Genia biological events are marked for uncertainty and/or negation. Results Differences among the annotations of the two corpora are thematically categorized and the frequency of each category is estimated. We found that the largest amount of differences is due to the issue that scopes – which cover text spans – deal with the key events and each argument (including events within events) of these events is under the scope as well. In contrast, Genia deals with the modality of events within events independently. Conclusions The analysis of multiple layers of annotation (linguistic scopes and biological events) showed that the detection of negation/hedge keywords and their scopes can contribute to determining the modality of key events (denoted by the main predicate). On the other hand, for the detection of the negation and speculation status of events within events, additional syntax-based rules investigating the dependency path between the modality cue and the event cue have to be employed.

2011-01-01

239

Precipitation induced stream flow: An event based chemical and isotopic study of a small stream in the Great Plains region of the USA  

USGS Publications Warehouse

A small stream in the Great Plains of USA was sampled to understand the streamflow components following intense precipitation and the influence of water storage structures in the drainage basin. Precipitation, stream, ponds, ground-water and soil moisture were sampled for determination of isotopic (D, 18O) and chemical (Cl, SO4) composition before and after two intense rain events. Following the first storm event, flow at the downstream locations was generated primarily through shallow subsurface flow and runoff whereas in the headwaters region - where a pond is located in the stream channel - shallow ground-water and pond outflow contributed to the flow. The distinct isotopic signatures of precipitation and the evaporated pond water allowed separation of the event water from the other sources that contributed to the flow. Similarly, variations in the Cl and SO4 concentrations helped identify the relative contributions of ground-water and soil moisture to the streamflow. The relationship between deuterium excess and Cl or SO4 content reveals that the early contributions from a rain event to streamflow depend upon the antecedent climatic conditions and the position along the stream channel within the watershed. The design of this study, in which data from several locations within a watershed were collected, shows that in small streams changes in relative contributions from ground water and soil moisture complicate hydrograph separation, with surface-water bodies providing additional complexity. It also demonstrates the usefulness of combined chemical and isotopic methods in hydrologic investigations, especially the utility of the deuterium excess parameter in quantifying the relative contributions of various source components to the stream flow. ?? 2006 Elsevier B.V. All rights reserved.

Machavaram, M. V.; Whittemore, D. O.; Conrad, M. E.; Miller, N. L.

2006-01-01

240

Does “High = High Risk”? An Event-Based Analysis of the Relationship Between Substance Use and Unprotected Anal Sex Among Gay and Bisexual Men  

Microsoft Academic Search

This study examined the relationship between substance use and condom use using a study design that remedied some of the methodological problems noted in prior research. A community sample of 147 gay men completed daily diaries in which they reported their substance use and sexual behaviors for 8 weeks. This method helped ensure the contiguity of substance use and sexual

Mary Rogers Gillmore; Diane M. Morrison; Barbara C. Leigh; Marilyn J. Hoppe; Jan Gaylord; Damian T. Rainey

2002-01-01

241

Executive and Theory-of-Mind Contributions to Event-Based Prospective Memory in Children: Exploring the Self-Projection Hypothesis  

ERIC Educational Resources Information Center

In two studies, 4- to 6-year-olds were asked to name pictures of animals for the benefit of a watching hand puppet (the ongoing task) but to refrain from naming and to remove from view any pictures of dogs (the prospective memory [PM] task). Children also completed assessments of verbal ability, cognitive inhibition, working memory, and…

Ford, Ruth M.; Driscoll, Timothy; Shum, David; Macaulay, Catrin E.

2012-01-01

242

Estimating the response effect of future events based on historical analogy: A methodology and illustration on generic substitution of brand-name drug sales following patent expiration  

Microsoft Academic Search

Managerial decisions often are made with considerable uncertainty about their possible effects. In assessing such problems, we often rely in an ad hoc fashion on analogous situations in the hope that they will shed light on the possible outcomes. This paper introduces a formal methodology for transferring information or data from one situation to another. A simple recursive least-squares approach

Wilfried R. Vanhonacker; Lydia J. Price

1995-01-01

243

Modeling of CIR-driven modulations of galactic cosmic ray intensity obtained by the Muon detector network  

NASA Astrophysics Data System (ADS)

The solar wind modulates Galactic Cosmic Ray (GCR) intensity. Modulations with a time scale of several days are mainly caused by Coronal Mass Ejections (CME) and solar wind stream interaction regions. The modulation caused by CME is called Forbush decrease (FD). The modulation that occurs at intervals of 27 days associated with Co-rotating Interaction Regions (CIR) is called recurrent storm. It has been considered that the mechanism of FD consists of two different processes as follows. (i) A turbulent region of solar wind magnetic field behind an interplanetary shock prevents incursion of GCR particles (shock effect). (ii) An interplanetary magnetic flux rope that has a low GCR density passes near the Earth (ejecta effect). A gradient of GCR density which is caused by an ejecta generates the flow of GCR called the B x grad n drift anisotropy. Therefore, the directional anisotropy of GCR intensity can be measured with ground-based observations [Bieber and Evenson, 1998]. Kuwabara et al. [2004] have established a model for reproducing both the temporal variations of isotropic intensity and the anisotropy of GCR measured by the Muon detector network. The shape of the GCR low density region inside ejecta is modeled with a cylinder. Since the CIR-driven GCR decrease accompanied by the directional anisotropy can be observed by the Muon detector network, it is expected that a low density region of GCR exists in the CIR structure. The mechanism of CIR-driven GCR decrease is still an open question. Using the data obtained by satellite observations, Richardson et al. [1996] investigated the relationship between the start time of GCR intensity decrease and the solar wind structure. They suggested that a turbulent region of solar wind magnetic field takes an important role in understanding the mechanism of modulation caused by CIR. However some problems are left. For example, the start time of GCR intensity decrease does not always correspond to the turbulent region of magnetic field. With these backgrounds, we assume a slab shape for the low density region caused by CIR and construct a model for reproducing temporal variations of isotropic intensity and the anisotropy of GCR measured by the Muon detector network. Details of this model will be reported. We will also discuss a relationship between the deduced low density region of GCR and the solar wind structure on the basis of some event studies of CIR- driven GCR modulations.

Okazaki, Y.; Fukunishi, H.; Munakata, K.

2006-12-01

244

Guiding Preservice Teachers to Critically Reflect: Towards a Renewed Sense about English Learners  

ERIC Educational Resources Information Center

The purpose of this practitioner inquiry was to explore the use of Guided Critical Reflection (GCR) in preparing preservice teachers for English learners (ELs). As a teacher researcher, I documented, analyzed, and discussed the ways in which students in my course used the process of GCR to transform their passively held understandings about ELs.…

Markos, Amy Michele

2011-01-01

245

Coordinate Regulation of an Extended Chromosome Domain  

Microsoft Academic Search

Spitz et al. (2003)([this issue of Cell]) describe the properties of a novel cis-regulatory DNA element, the global control region (GCR), which regulates gene expression over distances of several hundred kilobases at the mouse HoxD complex. The GCR provides an explanation for the colinear genetic linkage and expression of individual Hox genes within developing limbs.

Vincent C Calhoun; Michael Levine

2003-01-01

246

Master Plan for Improving Water Quality in the Grand Calumet River/Indiana Harbor Canal.  

National Technical Information Service (NTIS)

The Grand Calumet River/Indiana Harbor Canal (GCR/IHC) drains a narrow, heavily industrialized watershed area of northwest Indiana, at the southern tip of Lake Michigan. Water quality and aquatic habitat problems in the GCR/IHC have been a matter of publi...

1985-01-01

247

Corotating interaction regions and the 27 day variation of galactic cosmic rays intensity at 1 AU during the cycle 23/24 solar minimum  

NASA Astrophysics Data System (ADS)

We investigate the formation and evolution of corotating interaction regions (CIRs) in the solar wind and their effects on galactic cosmic rays (GCR) during the recent solar cycle 23/24 solar minimum. The output from a three-dimensional MHD model serves as background for kinetic time-dependent simulations of GCR transport based on the Parker equation. The results show that the CIR forward/reverse shock pairs or compression/rarefaction regions play important roles in the transport of GCR particles and directly control the observed 27 day periodic intensity variations. We find that stream interfaces (SIs) in CIRs and the heliospheric current sheet (HCS) are both closely associated with the GCR depression onset, in agreement with the observations at 1 AU. The HCS is more important when its tilt angle becomes small during the declining phase of the solar minimum, while the passages of SIs control the onset of GCR depressions for larger HCS tilt angles. The mechanism of GCR intensity variation near 1 AU can be explained through an interplay between the effects of particle drift and diffusion. The simulated plasma background and GCR intensity are compared with the observations from spacecraft and a neutron monitor on the ground, to find good qualitative agreement. Evidently, CIRs had a substantial modulational effect on GCR during the recent solar minimum.

Guo, X.; Florinski, V.

2014-04-01

248

Interplanetary Coronal Mass Ejections, Associated Features, and Transient Modulation of Galactic Cosmic Rays  

NASA Astrophysics Data System (ADS)

Interplanetary structures such as shocks, sheaths, interplanetary counterparts of coronal mass ejections (ICMEs), magnetic clouds, and corotating interaction regions (CIRs) are of special interest for the study of the transient modulation of galactic cosmic rays (GCRs). These structures modulate the GCR intensity with varying amplitudes and recovery-time profiles. It is known that ICMEs are mainly responsible for Forbush decreases in the GCR intensity. However, not all of the ICMEs produce such decreases in GCR intensity. We utilize GCR intensity data recorded by neutron monitors and solar-wind plasma/field data during the passage of ICMEs with different features and structures, and we perform a superposed-epoch analysis of the data. We also adopt the best-fit approach with suitable functions to interpret the observed similarities and differences in various parameters. Using the GCR-effectiveness as a measure of the cosmic-ray response to the passage of ICMEs, about half of the ICMEs identified during 1996 - 2009 are found to produce moderate to very large intensity depressions in GCR intensity. The ICMEs associated with halo CMEs, magnetic-cloud (MC) structures, bidirectional superthermal electron (BDE) signatures, and those driving shocks are 1.5 to 4 times more GCR effective than the ICMEs not associated with these structures/features. Further, the characteristic recovery time of GCR intensity due to shock/BDE/MC/halo-CME-associated ICMEs is larger than those due to ICMEs not associated with these structures/features.

Kumar, Anand; Badruddin

2014-06-01

249

Remodeling the oligosaccharides on ?-glucocerebrosidase using hydrophobic interaction chromatography and applications of hydroxyl ethyl starch for improving remodeling and enhancing protein stability.  

PubMed

In this article, we describe a hydrophobic interaction chromatography (HIC) method to remodel the carbohydrates on recombinant human ?-glucocerebrosidase (GCR) and the use of hydroxyl ethyl starch (HES) an ethylated starch polymer, to improve this process. GCR is a therapeutic protein used in the treatment of Gaucher disease, a life threatening condition in which patients lack sufficient functional levels of this enzyme. Gaucher disease is the most common inherited lysosomal storage disorder resulting in hepatomegaly, splenomegaly, and bone and lung pathology due to the accumulation of glucosylceramide in the lysosomes of macrophages (Beutler and Grabowski, 2001). The oligosaccharide remodeling of GCR, performed on HIC using three enzymes that remove sugars, increases macrophage uptake through the mannose receptor and thereby lowers its therapeutic dose versus unmodified GCR (Furbish et al., 1981; Van Patten et al., 2007). In this article we describe findings that the addition of HES lowered the amounts of three deglycosylating enzymes needed for remodeling GCR. HES also stabilized the activity of ?-glucosidase, ?-galactosidase, and GCR under conditions in which these three enzymes rapidly lose activity in the absence of this polymer. Circular dichroism (CD) and second derivative UV spectroscopy revealed that the secondary and tertiary structure of ?-glucosidase was unchanged while for GCR there was a slight compaction of the secondary structure but no apparent affect on the tertiary structure. The thermal stability of both GCR and ?-glucosidase were enhanced by HES as both molecules showed an increased transition midpoint (T(m)). PMID:22170377

Riske, Frank; Hamilton, Andrea; Zhang, Cheng; Hayes, Mike

2012-05-01

250

Issues in deep space radiation protection  

Microsoft Academic Search

The exposures in deep space are largely from the Galactic Cosmic Rays (GCR) for which there is as yet little biological experience. Mounting evidence indicates that conventional linear energy transfer (LET) defined protection quantities (quality factors) may not be appropriate for GCR ions. The available biological data indicates that aluminum alloy structures may generate inherently unhealthy internal spacecraft environments in

J. Miller; C. Zeitlin; L. Heilbronn; F. A. Cucinotta; G. D. Badhwar; A. K. Noor; M. Y. Kim; F. F. Badavi; J. H. Heinbockel

2001-01-01

251

Structure of the mouse glucocorticoid receptor: rapid analysis by size-exclusion high-performance liquid chromatography.  

PubMed

Gel-exclusion high-performance liquid chromatography (HPLC) has been used to separate the untransformed from the transformed glucocorticoid receptor (GC-R) extracted from mouse AtT-20 cells. With 200 mM potassium phosphate as the eluent, an efficient separation of the forms of the GC-R is attained in 15-20 min. The untransformed cytosolic GC-R elutes from the column with a Stokes radius (Rs) of 8.2-8.6 nm, as do the molybdate-stabilized GC-R, the purified untransformed GC-R, and the cross-linked cytosolic GC-R. GC-R transformed in vitro by either ammonium sulfate precipitation, KCl treatment, or G-25 chromatography elutes with an Rs of 5.7-6 nm. Also, GC-R extracted from the nucleus with either 0.3 M KCl or 2 mM sodium tungstate, or purified by two cycles of DNA-cellulose chromatography, has an Rs of 5.5-6.3 nm. The data are identical either in the presence or in the absence of 20 mM Na2MoO4, suggesting that molybdate is not causing aggregation to produce a larger Rs value than that of the native receptor. Vertical tube rotor sucrose gradient ultracentrifugation of cytosol produces three forms of the GC-R: 9.1 S, 5.2 S, and 3.8 S. Sequential analysis of the GC-R forms by HPLC and vertical tube rotor ultracentrifugation and vice versa allows for the hydrodynamic determination of molecular weight within a very short time period (2-3 h total).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3707935

LaPointe, M C; Chang, C H; Vedeckis, W V

1986-04-22

252

Stimulation of gross chromosomal rearrangements by the human CEB1 and CEB25 minisatellites in Saccharomyces cerevisiae depends on G-quadruplexes or Cdc13.  

PubMed

Genomes contain tandem repeats that are at risk of internal rearrangements and a threat to genome integrity. Here, we investigated the behavior of the human subtelomeric minisatellites HRAS1, CEB1, and CEB25 in Saccharomyces cerevisiae. In mitotically growing wild-type cells, these GC-rich tandem arrays stimulate the rate of gross chromosomal rearrangements (GCR) by 20, 1,620, and 276,000-fold, respectively. In the absence of the Pif1 helicase, known to inhibit GCR by telomere addition and to unwind G-quadruplexes, the GCR rate is further increased in the presence of CEB1, by 385-fold compared to the pif1? control strain. The behavior of CEB1 is strongly dependent on its capacity to form G-quadruplexes, since the treatment of WT cells with the Phen-DC(3) G-quadruplex ligand has a 52-fold stimulating effect while the mutation of the G-quadruplex-forming motif reduced the GCR rate 30-fold in WT and 100-fold in pif1? cells. The GCR events are telomere additions within CEB1. Differently, the extreme stimulation of CEB25 GCR depends on its affinity for Cdc13, which binds the TG-rich ssDNA telomere overhang. This property confers a biased orientation-dependent behavior to CEB25, while CEB1 and HRAS1 increase GCR similarly in either orientation. Furthermore, we analyzed the minisatellites' distribution in the human genome and discuss their potential role to trigger subtelomeric rearrangements. PMID:23133402

Piazza, Aurèle; Serero, Alexandre; Boulé, Jean-Baptiste; Legoix-Né, Patricia; Lopes, Judith; Nicolas, Alain

2012-01-01

253

Stimulation of Gross Chromosomal Rearrangements by the Human CEB1 and CEB25 Minisatellites in Saccharomyces cerevisiae Depends on G-Quadruplexes or Cdc13  

PubMed Central

Genomes contain tandem repeats that are at risk of internal rearrangements and a threat to genome integrity. Here, we investigated the behavior of the human subtelomeric minisatellites HRAS1, CEB1, and CEB25 in Saccharomyces cerevisiae. In mitotically growing wild-type cells, these GC–rich tandem arrays stimulate the rate of gross chromosomal rearrangements (GCR) by 20, 1,620, and 276,000-fold, respectively. In the absence of the Pif1 helicase, known to inhibit GCR by telomere addition and to unwind G-quadruplexes, the GCR rate is further increased in the presence of CEB1, by 385-fold compared to the pif1? control strain. The behavior of CEB1 is strongly dependent on its capacity to form G-quadruplexes, since the treatment of WT cells with the Phen-DC3 G-quadruplex ligand has a 52-fold stimulating effect while the mutation of the G-quadruplex-forming motif reduced the GCR rate 30-fold in WT and 100-fold in pif1? cells. The GCR events are telomere additions within CEB1. Differently, the extreme stimulation of CEB25 GCR depends on its affinity for Cdc13, which binds the TG-rich ssDNA telomere overhang. This property confers a biased orientation-dependent behavior to CEB25, while CEB1 and HRAS1 increase GCR similarly in either orientation. Furthermore, we analyzed the minisatellites‚ distribution in the human genome and discuss their potential role to trigger subtelomeric rearrangements.

Piazza, Aurele; Serero, Alexandre; Boule, Jean-Baptiste; Legoix-Ne, Patricia; Lopes, Judith; Nicolas, Alain

2012-01-01

254

Forbush decreases, solar irradiance variations, and anomalous cloud changes  

NASA Astrophysics Data System (ADS)

Changes in the galactic cosmic ray (GCR) flux due to variations in solar activity may provide an indirect connection between the Sun's and the Earth's climates. Epoch superpositional (composite) analyses of high-magnitude GCR fluctuations, known as Forbush decrease (FD) events, have been widely used to test this hypothesis, with varied results. This work provides new information regarding the interpretation of this approach, suggesting that FD events do not isolate the impacts of GCR variations from those of solar irradiance changes. On average, irradiance changes of ˜0.4 W m-2 outside the atmosphere occur around 2 days in advance of FD-associated GCR decreases. Using this 2 day gap to separate the effects of irradiance variations from GCR variations on cloud cover, we demonstrate small, but statistically significant, anomalous cloud changes occurring only over areas of the Antarctic plateau in association with the irradiance changes, which previous workers had attributed to GCR variations. Further analysis of the sample shows that these cloud anomalies occurred primarily during polar darkness, precluding the possibility of a causal link to a direct total solar irradiance effect. This work suggests that previous FD-based studies may have ineffectively isolated the impacts of GCR variations on the Earth's atmosphere.

Laken, Benjamin; Kniveton, Dominic; Wolfendale, Arnold

2011-05-01

255

Short-period variability in the galactic cosmic ray intensity: High statistical resolution observations and interpretation around the time of a Forbush decrease in August 2006  

NASA Astrophysics Data System (ADS)

On 20 August 2006 a Forbush decrease observed at Polar in the Earth's magnetosphere was also seen at the INTEGRAL spacecraft outside the magnetosphere during a very active time in the solar wind. High-resolution energetic particle data from ACE SIS, the Polar high-sensitivity telescope, and INTEGRAL's Ge detector saturation rate, which measures the galactic cosmic ray (GCR) background with a threshold of ˜200 MeV, show similar, short-period GCR variations in and around the Forbush decrease. Focusing upon the GCR intensity within a 3-day interval from 19 August 2006 to 21 August 2006 reveals many intensity variations in the GCR on a variety of time scales and amplitudes. These intensity variations are greater than the 3? error in all the data sets used. The fine structures in the GCR intensities along with the Forbush decrease are propagated outward from ACE to the Earth with very little change. The solar wind speed stays relatively constant during these periods, indicating that parcels of solar wind are transporting the GCR population outward in the heliosphere. This solar wind convection of GCR fine structure is observed for both increases and decreases in GCR intensity, and the fine structure increases and decreases are bracketed by solar wind magnetic field discontinuities associated with interplanetary coronal mass ejection (ICME) magnetosheath regions, clearly seen as discontinuous rotations of the field components at ACE and at Wind. Interestingly, the electron heat flux shows different flux tube connectivity also associated with the different regions of the ICME and magnetosheath. Gosling et al. (2004) first discussed the idea that solar energetic particle intensities commonly undergo dispersionless modulation in direct association with discontinuous changes in the solar wind electron strahl. The observations show that the intensity levels in the GCR flux may undergo a similar partitioning, possibly because of the different magnetic field regions having differing magnetic topologies.

Mulligan, T.; Blake, J. B.; Shaul, D.; Quenby, J. J.; Leske, R. A.; Mewaldt, R. A.; Galametz, M.

2009-07-01

256

System and method for diagnosis and treatment  

US Patent & Trademark Office Database

This invention relates to a low cost rapid response diagnostic system to determine cortisol levels in patients selected as potential candidates for GCR (glucocorticoid receptor) antagonist therapy utilizing a GCR antagonist, such as ORG 34517. The rapid, sensitive, and inexpensive test can be used to determine patients who have non-normal cortisol production or disordered circadian rhythms as a method for selecting subjects for GCR antagonist therapy for whom it is likely to have beneficial and/or therapeutic effects, and can also be used to monitor changes in cortisol levels in response to treatment.

2014-02-25

257

Voyager 1 UVS measurements of Galactic cosmic rays  

NASA Astrophysics Data System (ADS)

Detectors of the Ultra-Violet Spectrographs (UVS) on board the Voyagers provide independent measurements of galactic cosmic ray (GCR) fluxes. The energy and angular response are derived from correlative studies with other Voyager Instruments. We show the evolution of the GCR flux and anisotropy during and after the abrupt increases in 2012. Using data from UVS and other instruments we show strong evidence for the end of the GCR heliospheric modulation in the 300 MeV range at the present location of Voyager 1, in line with the flux steadiness since September 2012. This suggests that Voyager already entered the interstellar medium, and we discuss potential reasons.

Lallement, R.; Quemerais, E.; Bertaux, J.; Sandel, B. R.

2013-12-01

258

Increments in insulin sensitivity during intensive treatment are closely correlated with decrements in glucocorticoid receptor mRNA in skeletal muscle from patients with Type II diabetes.  

PubMed

To test the hypothesis that changes in the expression of the glucocorticoid receptor (GCR) and the beta(2)-adrenoceptor (beta(2)-AR) contribute significantly to the abnormal glucose metabolism in skeletal muscle from patients with Type II diabetes, we have examined (1) the levels of total GCR (alpha+beta isoforms), the alpha/alpha 2 isoform of GCR and beta(2)-AR mRNAs in skeletal muscle from insulin-resistant patients with Type II diabetes (n=10) and healthy controls (n=15), and (2) the effects of 8 weeks of intensive treatment on the whole-body glucose disposal rate and on total GCR, alpha/alpha 2 GCR and beta(2)-AR mRNA levels in diabetic patients. The total glucose disposal rate was measured by the euglycaemic hyperinsulinaemic (2 m-units x min(-1) x kg(-1)) clamp technique, and mRNA levels were assessed by reverse transcriptase-PCR and HPLC for separation of standard and unknown and quantification. Mean levels of total GCR and alpha/alpha 2 GCR mRNAs were increased in patients with Type II diabetes when compared with control subjects [total GCR, 2.06+/-0.30 and 1.47+/-0.10 amol/microg of total RNA respectively (P=0.09); alpha/alpha 2 GCR mRNA, 1.69+/-0.31 and 0.92+/-0.09 amol/microg of total RNA respectively (P=0.02)], whereas mRNA levels of the beta isoform of GCR (total GCR minus alpha/alpha 2 GCR) were decreased (P=0.006). beta(2)-AR mRNA levels were comparable in diabetic patients and control subjects (0.53+/-0.05 and 0.45+/-0.02 amol/microg of total RNA respectively; P=0.2). Intensive treatment for 8 weeks was associated with improved glycaemic control (P=0.019), and during the clamp a 75% (P=0.001) increase in the whole-body insulin-stimulated glucose disposal rate was demonstrated. Total GCR (P=0.005), alpha/alpha 2 GCR (P=0.005) and beta(2)-AR (P=0.03) mRNA levels all decreased significantly after intensive insulin treatment. A close correlation was found between increments in glucose uptake during intensive treatment and decrements in skeletal muscle total GCR mRNA (r=0.95, P<0.001; multiple regression analysis), and between glucose uptake and alpha/alpha 2 GCR m RNA levels (r=0.88, P<0.001; simple correlation). In conclusion, the abnormal regulation of GCR mRNA is likely to play a significant role in the insulin resistance observed in obese patients with Type II diabetes. PMID:11672459

Vestergaard, H; Bratholm, P; Christensen, N J

2001-11-01

259

Comparison of Space Radiation Calculations from Deterministic and Monte Carlo Transport Codes  

NASA Technical Reports Server (NTRS)

The presentation outline includes motivation, radiation transport codes being considered, space radiation cases being considered, results for slab geometry, results from spherical geometry, and summary. ///////// main physics in radiation transport codes hzetrn uprop fluka geant4, slab geometry, spe, gcr,

Adams, J. H.; Lin, Z. W.; Nasser, A. F.; Randeniya, S.; Tripathi, r. K.; Watts, J. W.; Yepes, P.

2010-01-01

260

Preliminary Design of a Galactic Cosmic Ray Shielding Materials Testbed for the International Space Station.  

National Technical Information Service (NTIS)

The preliminary design of a testbed to evaluate the effectiveness of galactic cosmic ray (GCR) shielding materials, the MISSE Radiation Shielding Testbed (MRSMAT) is presented. The intent is to mount the testbed on the Materials International Space Statio...

E. A. Sechkar J. R. Gaier S. Berkebile S. R. Panko

2012-01-01

261

OLTARIS: An Efficient Web-Based Tool for Analyzing Materials Exposed to Space Radiation.  

National Technical Information Service (NTIS)

The near-Earth space radiation environment includes energetic galactic cosmic rays (GCR), high intensity proton and electron belts, and the potential for solar particle events (SPE). These sources may penetrate shielding materials and deposit significant ...

A. M. McMullen C. A. Sandridge M. S. Clowdsley S. A. Thibeault S. R. Blatting T. Slaba

2011-01-01

262

Observations of the Li, Be, and B Isotopes and Constraints on Cosmic-ray Propagation  

NASA Technical Reports Server (NTRS)

The abundance of Li, Be, and B isotopes in galactic cosmic rays (GCR) between E=50-200 MeV/nucleon has been observed by the Cosmic Ray Isotope Spectrometer (CRIS) on NASA's ACE mission since 1997 with high statistical accuracy. Precise observations of Li, Be, B can be used to constrain GCR propagation models. We find that a diffusive reacceleration model with parameters that best match CRIS results (e.g. B/C, Li/C, etc) are also consistent with other GCR observations. A approx. 15-20% overproduction of Li and Be in the model predictions is attributed to uncertainties in the production cross-section data. The latter becomes a significant limitation to the study of rare GCR species that are generated predominantly via spallation.

deNolfo, G. A.; Moskalenko, I. V.; Binns, W. R.; Christian, E. R.; Cummings, A. C.; Davis, A. J.; George, J. S.; Hink, P. L.; Israel, M. H.; Leske, R. A.; Lijowski, M.; Mewaldt, R. A.; Stone, E. C.; Strong, A. W.; vonRosenvinge, T. T.; Wiedenbeck, M. E.; Yanasak, N. E.

2007-01-01

263

Simulation of Spatial and Temporal Radiation Exposures for ISS in the South Atlantic Anomaly.  

National Technical Information Service (NTIS)

The International Space Station (ISS) living areas receive the preponderance of ionizing radiation exposure from Galactic Cosmic Rays (GCR) and geomagnetically trapped protons. Practically all trapped proton exposure occurs when the ISS passes through the...

B. M. Anderson J. E. Nealy N. J. Luetke C. A. Sandridge G. E. Qualls

2004-01-01

264

The Radial Distribution of Galactic Cosmic Rays in the Heliosphere at Solar Minimum and Solar Maximum  

NASA Astrophysics Data System (ADS)

The radial intensity gradients, gr , for the qA>0 solar minimum periods of cycle 20 and 22 for 265 MeV/n galactic cosmic ray (GCR) He and 175 MeV GCR H are very small (<0.2%/AU) between 15 and 72 AU, suggesting that most of the GCR modulation at this time is occurring near the termination shock (T.S.) or in the heliosheath. The GCR latitudinal gradients (g? ) at this time are also small (<0.0 ± 0.2%/° ). For the qA<0 (1987), gr shows a much stronger radial dependence. The increased modulation from solar minimum to solar maximum is found to occur mainly inside the T.S.. In the inner heliosphere (r<15 AU) there does not appear to be a significant change in the particle transport parameters over the last 3 cycles.

McDonald, F. B.; Fujii, Z.; Heikkila, B.; Lal, N.; McGuire, R.E.

2003-07-01

265

Identification of Licopyranocoumarin and Glycyrurol from Herbal Medicines as Neuroprotective Compounds for Parkinson's Disease  

PubMed Central

In the course of screening for the anti-Parkinsonian drugs from a library of traditional herbal medicines, we found that the extracts of choi-joki-to and daio-kanzo-to protected cells from MPP+-induced cell death. Because choi-joki-to and daio-kanzo-to commonly contain the genus Glycyrrhiza, we isolated licopyranocoumarin (LPC) and glycyrurol (GCR) as potent neuroprotective principals from Glycyrrhiza. LPC and GCR markedly blocked MPP+-induced neuronal PC12D cell death and disappearance of mitochondrial membrane potential, which were mediated by JNK. LPC and GCR inhibited MPP+-induced JNK activation through the suppression of reactive oxygen species (ROS) generation, thereby inhibiting MPP+-induced neuronal PC12D cell death. These results indicated that LPC and GCR derived from choi-joki-to and daio-kanzo-to would be promising drug leads for PD treatment in the future.

Fujimaki, Takahiro; Saiki, Shinji; Tashiro, Etsu; Yamada, Daisuke; Kitagawa, Mitsuhiro; Hattori, Nobutaka; Imoto, Masaya

2014-01-01

266

Variations of galactic cosmic rays: modeling and observations  

NASA Astrophysics Data System (ADS)

We analyze relationships of different classes of galactic cosmic ray (GCR) intensity variations with parameters of solar wind, solar and geomagnetic activities, studding profiles of amplitudes and rigidity spectra. We demonstrate that the amplitudes of the first, second and third harmonics of the 27-day variation of the GCR intensity changes in a similar way, being greater in the A > 0 than in A < 0 polarity periods. We show that the amplitudes of the 27-day variation of the GCR anisotropy are greater in the A > 0 than in A < 0 polarity periods. The larger amplitudes of the 27-day variations of the GCR anisotropy and intensity in the minimum epochs of solar activity for the A > 0 polarity period than for the A < 0 period are related with the heliolongitudinal asymmetry of the solar wind velocity. We reveal the long -lived (˜22 years) active region of the heliolongitudes being the source of the long-lived 27-day variation of the solar wind velocity during the A > 0 polarity period. The 27-day variations of the GCR intensity and anisotropy have a sporadic character; appear and disappear as a wave packages with an average duration of 5-7 solar rotations. The ampli-tudes of the 27-day variations of the GCR intensity and anisotropy do not depend on the tilt angles of the heliospheric neutral sheet in both the A > 0 and A < 0 periods. We show that the rigidity spectra of the first, second and third harmonics of the 27-day variation of the GCR intensity change in a analogous manner, being hard in the maximum epochs and soft in the minimum epochs of solar activity. We ascribe this finding to the alternation of the sizes of the modulation regions of the 27-day variation of the GCR intensity in different epochs of solar activity. We also show that the temporal changes of the power rigidity spectrum of the harmonics of the 27-day variation of the GCR intensity are negatively correlated with the rigidity spectrum of the 11-year variation of the galactic cosmic ray intensity. We propose the full 3-D stationary model describing the GCR variations including diffusion, convection, drift and the energy changes of the particles based on the Parker's transport equa-tion. We show that our models explain well the profiles of the behavior of the amplitudes and the rigidity spectrum exponent ? of the GCR variations. Our theoretical calculations are in a good agreement with the results obtained based on the neutron monitors experimental data.

Gil, Agnieszka

267

History of the solar environment  

NASA Astrophysics Data System (ADS)

Galactic cosmic rays (GCR) provide information on the solar neighborhood during the sun's motion in the galaxy. There is now considerable evidence for GCR acceleration by shock waves of supernova in active star-forming regions (OB associations) in the galactic spiral arms. During times of passage into star-forming regions increases in the GCR-flux are expected. Recent data from the Spitzer Space Telescope (SST) are shedding light on the structure of the Milky Way and of its star-forming-regions in spiral arms. Records of flux variations may be found in solar system detectors, and iron meteorites with GCR-exposure times of several hundred million years have long been considered to be potential detectors (Voshage, 1962). Variable concentration ratios of GCR-produced stable and radioactive nuclides, with varying half-lives and therefore integration times, were reported by Lavielle et al. (1999), indicating a recent 38% GCR-flux increase. Potential flux recorders consisting of different pairs of nuclides can measure average fluxes over different time scales (Lavielle et al., 2007; Mathew and Marti, 2008). Specific characteristics of two pairs of recorders (81Kr-Kr and 129I-129Xe) are the properties of self-correction for GCR-shielding (flux variability within meteorites of varying sizes). The 81Kr-Kr method (Marti, 1967) is based on Kr isotope ratios, while stable 129Xe is the decay product of the radionuclide 129I, which is produced by secondary neutron reactions on Te in troilites of iron meteorites. The two chronometers provide records of the average GCR flux over 1 and 100 million year time scales, respectively.

Marti, Kurt; Lavielle, Bernard

2009-03-01

268

Initiation-promotion model of tumor prevalence in mice from space radiation exposures  

Microsoft Academic Search

Exposures in space consist of low-level background components from galactic cosmic rays (GCR), occasional intense-energetic solar-particle events, periodic passes through geomagnetic-trapped radiation, and exposure from possible onboard nuclear-propulsion engines. Risk models for astronaut exposure from such diverse components and modalities must be developed to assure adequate protection in future. NASA missions. The low-level background exposures (GCR), including relativistic heavy ions

Francis A. Cucinotta; John W. Wilson

1995-01-01

269

A temporal forecast of radiation environments for future space exploration missions  

Microsoft Academic Search

The understanding of future space radiation environments is an important goal for space mission operations, design, and risk\\u000a assessment. We have developed a solar cycle statistical model in which sunspot number is coupled to space-related quantities,\\u000a such as the galactic cosmic radiation (GCR) deceleration potential (?) and the mean occurrence frequency of solar particle\\u000a events (SPEs). Future GCR fluxes were

Myung-Hee Y. Kim; Francis A. Cucinotta; John W. Wilson

2007-01-01

270

Cosmogenic-nuclide production by primary cosmic-ray protons  

SciTech Connect

The production rates of cosmogenic nuclides were calculated for the primary protons in the galactic and solar cosmic rays. At 1 AU, the long-term average fluxes of solar protons usually produce many more atoms of a cosmogenic nuclide than the primary protons in the GCR, the exceptions being nuclides made only by high-energy reactions (like Be-10). Because the particle fluxes inside meteorites and other large objects in space include many secondary neutrons, the production rates and ratios inside large objects are often very different from those by just the primary GCR protons. Thus it is possible to determine, by examining its cosmogenic nuclides, if a small object, such as found among deep-sea spherules, was small in space or broken from a meteorite. Because heliospherical modulation and other interactions change the GCR particle spectrum, the production of cosmogenic nuclides by the GCR particles outside the heliosphere will be different from that by modulated GCR primaries. Production rates and ratios for cosmogenic nuclides would be able to identify small particles, possibly interstellar in origin, that were exposed to an unmodulated spectrum of GCR particles and to characterize the spectrum of particles to which they were exposed. 6 refs., 1 tab.

Reedy, R.C.

1985-01-01

271

Galactic Cosmic Ray Access to the Inner Magnetosphere Measured by the Relativistic Proton Spectrometer aboard the Van Allen Probes  

NASA Astrophysics Data System (ADS)

The Relativistic Proton Spectrometer (RPS) aboard the Van Allen Probes is designed to measure the energy and angular distributions of protons with energies of about 50 MeV to 2 GeV that are trapped in the Earth's inner radiation belt. The upper end of this energy range also covers the peak of the galactic cosmic ray (GCR) spectrum, and when each spacecraft is near apogee we obtain a clean sample of GCR protons at locations well outside the region populated by trapped protons at these energies. As each spacecraft moves closer to Earth, the increasing strength of the geomagnetic field shunts away protons of progressively higher energies, a process that can be studied by analyzing the changes in the measured GCR spectrum as the sensor is carried toward and back away from apogee. In addition, the spin of the Van Allen Probes spacecraft allows us to study the east-west asymmetry of GCR protons, as the arcs of gyration of the protons that are measured at the spacecraft bring them to the sensors along different tracks through the outer parts of the Earth's magnetic field. We will present observations of these effects from the lowest altitudes reached by GCR protons out to apogee at about L = 6 over the mission to date, using data from the CRaTER sensor aboard the Lunar Reconnaissance Orbiter as a baseline for variations of the GCR flux well outside the magnetosphere.

Looper, M. D.; Mazur, J. E.; O'Brien, T. P.; George, J. S.

2013-12-01

272

Computational and Genetic Reduction of a Cell Cycle to Its Simplest, Primordial Components  

PubMed Central

What are the minimal requirements to sustain an asymmetric cell cycle? Here we use mathematical modelling and forward genetics to reduce an asymmetric cell cycle to its simplest, primordial components. In the Alphaproteobacterium Caulobacter crescentus, cell cycle progression is believed to be controlled by a cyclical genetic circuit comprising four essential master regulators. Unexpectedly, our in silico modelling predicted that one of these regulators, GcrA, is in fact dispensable. We confirmed this experimentally, finding that ?gcrA cells are viable, but slow-growing and elongated, with the latter mostly due to an insufficiency of a key cell division protein. Furthermore, suppressor analysis showed that another cell cycle regulator, the methyltransferase CcrM, is similarly dispensable with simultaneous gcrA/ccrM disruption ameliorating the cytokinetic and growth defect of ?gcrA cells. Within the Alphaproteobacteria, gcrA and ccrM are consistently present or absent together, rather than either gene being present alone, suggesting that gcrA/ccrM constitutes an independent, dispensable genetic module. Together our approaches unveil the essential elements of a primordial asymmetric cell cycle that should help illuminate more complex cell cycles.

Fumeaux, Coralie; Viollier, Patrick H.; Howard, Martin

2013-01-01

273

Effects of Cutoffs on Galactic Cosmic-Ray Interactions in Solar-System Matter  

NASA Technical Reports Server (NTRS)

The energetic particles in the galactic cosmic rays (GCR) induce many interactions in a variety of solar-system matter. Cosmogenic nuclides are used to study the histories of meteorites and lunar samples. Gamma rays and neutrons are used to map the compositions of planetary surfaces, such as Mars, the Moon, and asteroids. In almost all of these cases, the spectra of incident GCR particles are fairly similar, with only some modulation by the Sun over an 11-year cycle. Strong magnetic fields can seriously affect the energy spectrum of GCR particles hitting the surface of objects inside the magnetic fields. The Earth s geomagnetic field is strong enough that only GCR particles with magnetic rigidities above approx. 17 GV (a proton energy of approx. 17 GeV) reach the atmosphere over certain regions near the equator. This effect of removing lower-energy GCR particles is called a cutoff. The jovian magnetic fields are so strong that the fluxes of GCR particles hitting the 4 large Galilean satellites are similarly affected. The cutoff at Europa is estimated to be similar to or a little higher than at the Earth s equator.

Kim, K. J.; Reedy, R. C.; Masarik, J.

2005-01-01

274

Galactic cosmic ray variations at the moon  

NASA Astrophysics Data System (ADS)

Galactic Cosmic Rays (GCR) are the predominant source of highly energetic particles in the inner heliosphere during solar quiet times. These particles are fully ionized atoms that are accelerated to near-relativistic speeds during events of extreme energy release throughout the Milky Way Galaxy and beyond. Some GCR particles eventually find their way to the outer edges of the heliosphere and a portion of those are able to propagate to 1 AU. GCR have sufficient energy to ionize atoms and molecules in the matter that they impact, causing radiation damage to both robotic and biologic materials. Understanding the flux and spectrum of GCR is of great importance to future robotic and human explorers venturing beyond low-Earth orbit. In this dissertation, we use the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument along with modeling efforts to study a variety of phenomena that can influence the energetic particle flux in the near-Moon environment, including Interplanetary Coronal Mass Ejections (ICMEs), Corotating Interaction Regions (CIRs) and the Earth's magnetotail. As part of this study, the CRaTER instrument and its calibration are discussed in detail. A new model is developed to better predict the transit times of Interplanetary Coronal Mass Ejections and the associated drops in GCR flux called Forbush decreases. This model could provide a more accurate estimate of an ICME's arrival time within hours of ejection from the Sun. An important model discrepancy is resolved by using the CRaTER instrument to measure GCR while the Moon is in the Earth's magnetotail. Previous studies that predicted shielding of GCR by the magnetotail are disproven; we find no evidence for a drop in GCR, intensity as a result of passage through the magnetotail. We use the CRaTER instrument to investigate step-like durable decreases in GCR flux with time. We find that these decreases occurred when CIRs convected past the observing spacecraft shortly after solar minimum, presumably caused by the more effective shielding provided by the outward propagating magnetic structures. A change in the proton linear energy transfer spectrum is observed in conjunction with the GCR flux decrease.

Case, Anthony W.

2011-05-01

275

Calculation of The Ti Activity In 44 Chondrites Which Fell In The Last Two Centuries and Comparison With Measurements  

NASA Astrophysics Data System (ADS)

The cosmogenic radioisotopes in meteorites, produced by nuclear interactions of the galactic cosmic rays (GCR) with the meteoroids in the interplanetary space are good proxies of both the GCR flux and the solar activity. Different cosmogenic radionu- clides with different half-lives give information over different time scales. Recently we have inferred the GCR annual mean spectra for the last 300 years [1]. The most prominent result concerns the cosmic ray flux during prolonged solar quiet periods. We deduced that during the Maunder minimum of solar acivity (1700), the Dal- ton minimum (1800) and the Modern minimum (1900) the GCR flux was much higher (2 times) respect to the flux observed in the last decades. Utilizing these GCR spectra we have calculated the 44 Ti (T1/2 = 59.2 y) activity in meteorites taking into account its exitation function for production from the main target element Fe, Ni and Ti [2]. Furthermore, in the last years we have measured the very low activity of the cosmogenic 44Ti in different fell chondrites and now our data cover the interval 1810 to present. The calculated 44Ti profile is in close agreement with the observed mea- surements. This result demonstrates that our inference of the GCR flux in the past 300 years is reliable. The cosmogenic 44Ti in meteorites is a unique tool, free from ter- restrial influences, for validation of both the GCR flux and the heliospheric behaviour over century time scale. [1] G. Bonino, G. Cini Castagnoli, D. Cane, C. Taricco and N. Bhandari, Proc. XXVII Intern. Cosmic Ray Conf. (Hamburg, 2001) 3769-3772. [2] R. Michel and S. Neumann (1998) Proc. Indian Acad. Sci. Earth Planet. Sci. , 107, 441-457.

Bonino, G.; Cane, D.; Cini Castagnoli, G.; Taricco, C.; Bhandari, N.

276

Modeling of galactic cosmic rays transport in the three dimensional interplanetary magnetic field  

NASA Astrophysics Data System (ADS)

Model of galactic cosmic rays (GCR) transport based on the generalized anisotropic diffusion tensor for the three dimensional interplanetary magnetic field (IMF) taking into account diffusion, convection, energy change due to interaction of GCR with the diverged solar wind and drifts of particles due to gradient and curvature of the regular IMF and on the heliospheric neutral sheet (HNS) has been considered. The components of the HNS drift velocity have been found for the various types of the three dimensional IMF suggested by different authors. The spatial distribution of different components of the generalized anisotropic diffusion tensor were calculated in the case of the existence of the latitudinal component of the IMF and their roles in the GCR modulation in the inner and outer heliosphere have been estim ated. It is shown that in equal other conditions a modulation of GCR is deeper for any kind of types of the three dimensional IMF in comparing with the two dimensional IMF if the existence of the latitudinal component leads to the increase of the module of the IMF. The expected spatial distributions of the density, gradients, fluxes and anisotropy of GCR have been found for the different values of the regular latitudinal component B of the IMF, B =1.5 nT and B = 2.5 nT. The expected anisotropy obtained from the numerical solution of transport equation is compared with the results of the anisotropy of GCR calculated by the experimental data of neutron monitors for different solar magnetic cycles of the qA>0 and qA<0. An importance of the modeling of GCR transport in the interplanetary space based on the generalized anisotropic diffusion tensor for the three dimensional IMF has been widely discussed.

Wawrzynczak, A.; Alania, M.

277

Badhwar-O'Neill 2011 Galactic Cosmic Ray Model Update and Future Improvements  

NASA Technical Reports Server (NTRS)

The Badhwar-O'Neill Galactic Cosmic Ray (GCR) Model based on actual GCR measurements is used by deep space mission planners for the certification of microelectronic systems and the analysis of radiation health risks to astronauts in space missions. The BO GCR Model provides GCR flux in deep space (outside the earth's magnetosphere) for any given time from 1645 to present. The energy spectrum from 50 MeV/n - 20 GeV/n is provided for ions from hydrogen to uranium. This work describes the most recent version of the BO GCR model (BO'11). BO'11 determined the GCR flux at a given time applying an emperical time delay function to past sunspot activity. We describe the GCR measurement data used in the BO'11 update - modern data from BESS, PAMELA, CAPRICE, and ACE emphasized more than the older balloon data used for the previous BO model (BO'10). We look at the GCR flux for the last 24 solar minima and show how much greater the flux was for the cycle 24 minimum in 2010. The BO'11 Model uses the traditional, steady-state Fokker-Planck differential equation to account for particle transport in the heliosphere due to diffusion, convection, and adiabatic deceleration. It assumes a radially symmetrical diffusion coefficient derived from magnetic disturbances caused by sunspots carried outward by a constant solar wind. A more complex differential equation is now being tested to account for particle transport in the heliosphere in the next generation BO model. This new model is time-dependent (no longer a steady state model). In the new model, the dynamics and anti-symmetrical features of the actual heliosphere are accounted for so emperical time delay functions will no longer be required. The new model will be capable of simulating the more subtle features of modulation - such as the Sun's polarity and modulation dependence on gradient and curvature drift. This improvement is expected to significantly improve the fidelity of the BO GCR model. Preliminary results of its performance will be presented.

O'Neill, Pat M.; Kim, Myung-Hee Y.

2014-01-01

278

The orphan protein bis-?-glutamylcystine reductase joins the pyridine nucleotide disulfide reductase family.  

PubMed

Facile DNA sequencing became possible decades after many enzymes had been purified and characterized. Consequently, there are still "orphan" enyzmes for which activities are known but for which encoding genes have not been identified. Identification of the genes encoding orphan enzymes is important because it allows correct annotation of genes of unknown function or with misassigned function. Bis-?-glutamylcystine reductase (GCR) is an orphan protein that was purified in 1988. This enzyme catalyzes the reduction of bis-?-glutamylcystine. ?-Glutamylcysteine is the major low-molecular weight thiol in halobacteria. We purified GCR from Halobacterium sp. NRC-1 and identified the sequence of 23 tryptic peptides by nano-liquid chromatography electrospray ionization tandem mass spectrometry. These peptides cover 62% of the protein predicted to be encoded by a gene in Halobacterium sp. NRC-1 that is annotated as mercuric reductase. GCR and mercuric reductase activities were assayed using enzyme that was expressed in Escherichia coli and refolded from inclusion bodies. The enzyme had robust GCR activity but no mercuric reductase activity. The genomes of most, but not all, halobacteria for which whole genome sequences are available have close homologues of GCR, suggesting that there is more to be learned about the low-molecular weight thiols used in halobacteria. PMID:23560638

Kim, Juhan; Copley, Shelley D

2013-04-30

279

Search for cosmogenic Ar-42 in meteorites  

NASA Astrophysics Data System (ADS)

We have evidence for decreasing galactic cosmic ray (GCR) flux in the past 3 centuries by a factor about two [1]. The measurements of the activity of cosmogenic 44Ti (T1/2 = 59.2 y) produced by GCR in stony meteorites that fell during the last two centuries are in good agreement with the calculated values and validate the decreasing trend of GCR flux. The measurements were obtained by an hyperpure (372 cm3) Ge-NaI(Tl) spectrometer operating in the Monte dei Cappuccini laboratory in Torino[2]. To further improve upon statistical precision of 44Ti data and also to be able to measure the 42Ar (T1/2 = 33 y) which is produced in even smaller amounts by GCR in meteorites, we have set up in the same laboratory a larger (581 cm3) hyperpure Ge detector operating in coincidence with a 100 kg NaI(Tl) crystal assembly. This should enable us to confirm the above results about GCR variations. We wish to acknowledge our deep gratitude to professor Bonino, deceased on September 29, 2002, to whom the assemblage of the new equipment is due. [1] G. Bonino, G. Cini Castagnoli, D. Cane, C. Taricco and N. Bhandari,Proc. XXVII Intern. Cosmic Ray Conf. (Hamburg, 2001) 3769-3772. [2] Bonino G., Cini Castagnoli G., Cane D., Taricco C., Bhandari N, textit {34th COSPAR Sci. Ass. Houston 2002 (Adv. Space Res.)}, in press

Cini Castagnoli, G.; Cane, D.; Taricco, C.; Bhandari, N.

2003-04-01

280

Nuclide production by primary cosmic-ray protons  

SciTech Connect

The production rates of cosmogenic nuclides in the solar system and in interstellar space were calculated for the primary protons in the galactic and solar cosmic rays. At 1 AU, the long-term average fluxes of solar protons usually produce many more atoms of a cosmogenic nuclide than the primary protons in the galactic cosmic rays (GCR), the exceptions being nuclides made only by high-energy reactions (like /sup 10/Be). Because the particle fluxes inside meteorites and other large objects in space include many secondary neutrons, the production rates are much higher and ratios inside large objects are often very different from those by just the primary GCR protons in small objects. The production rates of cosmogenic nuclides are calculated to vary by about factors of 2.5 during at typical 11-year solar cycle, in agreement with measurements of short-lived radionuclides in recently fallen meteorites. The production of cosmogenic nuclides by the GCR particles outside the heliosphere is higher than that by the modulated GCR primaries normally in the solar system. However, there is considerable uncertainty in the fluxes of interstellar protons and, therefore, in the production rates of cosmogenic nuclides in interstellar space. Production rates and ratios for cosmogenic nuclides would be able to identify particles that were small in space or that were exposed to an unmodulated spectrum of GCR particles. 25 refs., 2 figs., 2 tabs.

Reedy, R.C.

1986-01-01

281

Interstellar propagation and electron capture processes of galactic cosmic ray heavy ions in space  

NASA Technical Reports Server (NTRS)

The new information on galactic cosmic rays (GCR) derived from the Spacelab-3 cosmic ray experiment 'Anuradha' shows that at 25-125 MeV/N GCR sub-iron and iron (Z = 21-28) particles consists of a mixture of partially ionized and fully ionized ions. Computation of electron capture and loss cross sections in hydrogen in 1-50 MeV/N energy range are made for Fe, Cr, Ti and Ni. From these it is concluded that: (1) these GCR particles must have captured orbital electrons at energies of about 1-5 MeV/N and (2) these particles are then reaccelerated to 300-500 MeV/N most probably in interstellar medium by collision with SNR shock fronts. Some reacceleration may take place also in heliospheric boundary region. It is suggested that these observations of partially ionized GCR ions of about 100 MeV/N in Spacelab-3 provide a direct evidence of reacceleration of GCR.

Miltra, B.; Biswas, S.; Goswami, J. N.

1995-01-01

282

Evaluating Shielding Effectiveness for Reducing Space Radiation Cancer Risks  

NASA Technical Reports Server (NTRS)

We discuss calculations of probability distribution functions (PDF) representing uncertainties in projecting fatal cancer risk from galactic cosmic rays (GCR) and solar particle events (SPE). The PDF s are used in significance tests of the effectiveness of potential radiation shielding approaches. Uncertainties in risk coefficients determined from epidemiology data, dose and dose-rate reduction factors, quality factors, and physics models of radiation environments are considered in models of cancer risk PDF s. Competing mortality risks and functional correlations in radiation quality factor uncertainties are treated in the calculations. We show that the cancer risk uncertainty, defined as the ratio of the 95% confidence level (CL) to the point estimate is about 4-fold for lunar and Mars mission risk projections. For short-stay lunar missions (<180 d), SPE s present the most significant risk, however one that is mitigated effectively by shielding, especially for carbon composites structures with high hydrogen content. In contrast, for long duration lunar (>180 d) or Mars missions, GCR risks may exceed radiation risk limits, with 95% CL s exceeding 10% fatal risk for males and females on a Mars mission. For reducing GCR cancer risks, shielding materials are marginally effective because of the penetrating nature of GCR and secondary radiation produced in tissue by relativistic particles. At the present time, polyethylene or carbon composite shielding can not be shown to significantly reduce risk compared to aluminum shielding based on a significance test that accounts for radiobiology uncertainties in GCR risk projection.

Cucinotta, Francis A.; Kim, Myung-Hee Y.; Ren, Lei

2007-01-01

283

Study the effect of gray component replacement level on reflectance spectra and color reproduction accuracy  

NASA Astrophysics Data System (ADS)

The aim of this study is investigation of gray component replacement (GCR) levels on reflectance spectrum for different overprints of the inks and color reproduction accuracy. The most commonly implemented method in practice for generation of achromatic composition is gray component replacement (GCR). The experiments in this study, have been performed in real production conditions with special test form generated by specialized software. The measuring of reflection spectrum of printed colors, gives a complete conception for the effect of different gray component replacement levels on color reproduction accuracy. For better data analyses and modeling of processes, we have calculated (converted) the CIEL*a*b* color coordinates from the reflection spectra data. The assessment of color accuracy by using different GCR amount has been made by calculation of color difference ?E* ab. In addition for the specific printing conditions we have created ICC profiles with different GCR amounts. A comparison of the color gamuts has been performed. For a first time a methodology is implemented for examination and estimation of effect of GCR levels on color reproduction accuracy by studying a big number of colors in entire visible spectrum. Implementation in practice of the results achieved in this experiment, will lead to improved gray balance and better color accuracy. Another important effect of this research is reduction of financial costs of printing production by decreasing of ink consumption, indirect reduction of emissions during the manufacture of inks and facilitates the process of deinking during the recycling paper.

Spiridonov, I.; Shopova, M.; Boeva, R.

2013-03-01

284

Tumor Necrosis Factor Inhibits Glucocorticoid Receptor Function in Mice  

PubMed Central

As glucocorticoid resistance (GCR) and the concomitant burden pose a worldwide problem, there is an urgent need for a more effective glucocorticoid therapy, for which insights into the molecular mechanisms of GCR are essential. In this study, we addressed the hypothesis that TNF?, a strong pro-inflammatory mediator in numerous inflammatory diseases, compromises the protective function of the glucocorticoid receptor (GR) against TNF?-induced lethal inflammation. Indeed, protection of mice by dexamethasone against TNF? lethality was completely abolished when it was administered after TNF? stimulation, indicating compromised GR function upon TNF? challenge. TNF?-induced GCR was further demonstrated by impaired GR-dependent gene expression in the liver. Furthermore, TNF? down-regulates the levels of both GR mRNA and protein. However, this down-regulation seems to occur independently of GC production, as TNF? also resulted in down-regulation of GR levels in adrenalectomized mice. These findings suggest that the decreased amount of GR determines the GR response and outcome of TNF?-induced shock, as supported by our studies with GR heterozygous mice. We propose that by inducing GCR, TNF? inhibits a major brake on inflammation and thereby amplifies the pro-inflammatory response. Our findings might prove helpful in understanding GCR in inflammatory diseases in which TNF? is intimately involved.

Van Bogaert, Tom; Vandevyver, Sofie; Dejager, Lien; Van Hauwermeiren, Filip; Pinheiro, Iris; Petta, Ioanna; Engblom, David; Kleyman, Anna; Schutz, Gunther; Tuckermann, Jan; Libert, Claude

2011-01-01

285

Super-TIGER: A Balloon-Borne Instrument to Probe Galactic Cosmic Ray Origins  

NASA Astrophysics Data System (ADS)

Super-TIGER (Super Trans-Iron Galactic Element Recorder) is a balloon-borne instrument under construction for a long-duration flight from Antarctica in 2012. It is designed to measure the relative abundances of the ultra-heavy (UH) Galactic cosmic rays (GCR) with individual-element resolution from _{30}Zn to _{42}Mo and make exploratory measurements through _{56}Ba, as well as the energy spectra of the GCR from _{10}Ne to _{29}Cu between 0.8 and 10 GeV/nucleon. The UH measurements will test the OB association origin model of the GCR, as well as the model of preferential acceleration of refractory elements. The GCR spectrum measurements will probe for microquasars or other sources that could superpose spectral features. Super-TIGER is a ˜ 4 × larger evolution of the preceding TIGER instrument, and is comprised of two independent modules with a total area of 5.4 m^{2}. A combination of plastic scintillation detectors, acrylic and silica-aerogel Cherenkov detectors, and scintillating fiber hodoscopes are used to resolve particle charge, kinetic energy per nucleon, and trajectory. Refinements in the Super-TIGER design over TIGER, including reduced material in the beam, give it a collecting power that is ˜ 6.4× larger. This paper will report on the instrument development status, the expected flight performance, and the scientific impact of the anticipated Super-TIGER GCR measurements. This research was supported by NASA under Grant NNX09AC17G

Rauch, Brian

2012-07-01

286

Local galactic cosmic ray increases within the sheaths of interplanetary coronal mass ejections  

NASA Astrophysics Data System (ADS)

Interplanetary coronal mass ejections (ICMEs) can cause reductions, known as Forbush decreases (Fds), in galactic cosmic ray (GCR) intensities. Two-step Fds occur when both an ICME and its shock encounter a GCR detector. We find 80 ICMEs from 1998 to 2006 that, according to this model, should have created two-step Fds. In 27 of the events, however, a local increase in the GCRs was superposed on the overall decrease of the Fd within the ICME sheath. We discover that these increases generally occur more than a correlation length away from the shock. This implies that the GCR features do not result from turbulence in the interplanetary magnetic field. Therefore we hypothesize that magnetic structure in the sheath may create conduits for the GCRs, thus creating the increases.

Jordan, A.; Spence, H. E.; Blake, J.; Shaul, D. N.; Giacalone, J.

2010-12-01

287

A model of galactic cosmic rays for use in calculating linear energy transfer spectra.  

PubMed

The galactic cosmic rays (GCR) contain fully stripped nuclei, from Hydrogen to beyond the Iron group, accelerated to high energies and are a major component of the background radiation encountered by satellites and interplanetary spacecraft. This paper presents a GCR model which is based upon our current understanding of the astrophysics of GCR transport through interstellar and interplanetary space. The model can be used to predict the energy spectra for all stable and long-lived radioactive species from H to Ni over an energy range from 50 to 50,000 MeV/nucleon as a function of a single parameter, the solar modulation level phi. The details of this model are summarized, phi is derived for the period 1974 to present, and results from this model during the 1990/1991 CRRES mission are presented. PMID:11540022

Chen, J; Chenette, D; Clark, R; Garcia-Munoz, M; Guzik, T G; Pyle, K R; Sang, Y; Wefel, J P

1994-10-01

288

Stopping powers and cross sections due to two-photon processes in relativistic nucleus-nucleus collision  

NASA Technical Reports Server (NTRS)

The radiation dose received from high energy galactic cosmic rays (GCR) is a limiting factor in the design of long duration space flights and the building of lunar and martian habitats. It is of vital importance to have an accurate understanding of the interactions of GCR in order to assess the radiation environment that the astronauts will be exposed to. Although previous studies have concentrated on the strong interaction process in GCR, there are also very large effects due to electromagnetic (EM) interactions. In this report we describe our first efforts at understanding these EM production processes due to two-photon collisions. More specifically, we shall consider particle production processes in relativistic heavy ion collisions (RHICs) through two-photon exchange.

Cheung, Wang K.; Norbury, John W.

1992-01-01

289

Updated Computational Model of Cosmic Rays Near Earth  

NASA Technical Reports Server (NTRS)

An updated computational model of the galactic-cosmic-ray (GCR) environment in the vicinity of the Earth, Earth s Moon, and Mars has been developed, and updated software has been developed to implement the updated model. This model accounts for solar modulation of the cosmic-ray contribution for each element from hydrogen through iron by computationally propagating the local interplanetary spectrum of each element through the heliosphere. The propagation is effected by solving the Fokker-Planck diffusion, convection, energy-loss boundary-value problem. The Advanced Composition Explorer NASA satellite has provided new data on GCR energy spectra. These new data were used to update the original model and greatly improve the accuracy of prediction of interplanetary GCR.

ONeill, Patrick M.

2006-01-01

290

Experimental Plans for Subsystems of a Shock Wave Driven Gas Core Reactor  

NASA Technical Reports Server (NTRS)

This Contractor Report proposes a number of plans for experiments on subsystems of a shock wave driven pulsed magnetic induction gas core reactor (PMI-GCR, or PMD-GCR pulsed magnet driven gas core reactor). Computer models of shock generation and collision in a large-scale PMI-GCR shock tube have been performed. Based upon the simulation results a number of issues arose that can only be addressed adequately by capturing experimental data on high pressure (approx.1 atmosphere or greater) partial plasma shock wave effects in large bore shock tubes ( 10 cm radius). There are three main subsystems that are of immediate interest (for appraisal of the concept viability). These are (1) the shock generation in a high pressure gas using either a plasma thruster or pulsed high magnetic field, (2) collision of MHD or gas dynamic shocks, their interaction time, and collision pile-up region thickness, and (3) magnetic flux compression power generation (not included here).

Kazeminezhad, F.; Anghai, S.

2008-01-01

291

Assessment of Galactic Cosmic Ray Models and Implications on the Estimation of Radiation Exposure in Space  

NASA Astrophysics Data System (ADS)

Astronauts are subjected to elevated levels of high-energy ionizing radiation in space which poses a substantial risk to their health. Therefore, the assessment of the radiation exposure for long duration manned spaceflight is essential. This is done by measuring dose using various detector techniques and by performing numerical simulations utilizing radiation transport codes which allow to predict radiation exposure for future missions and for conditions where measurements are not feasible or available. A necessary prerequisite for an accurate estimation of the exposure using the latter approach is a reliable description of the radiation spectra. Accordingly, in order to estimate the exposure from the Galactic Cosmic Rays (GCRs), which are one of the major sources of radiation exposure in space, GCR models are required. This work presents an evaluation of GCR models for dosimetry purposes and the effect of applying these models on the estimation of GCR exposure in space outside and inside the Earth's magnetosphere. To achieve this, widely used GCR models - Badhwar-O'Neill2010, Burger-Usoskin, CREME2009 and CREME96, were evaluated by comparing model spectra for light and heavy nuclei with measurements from various high-altitude balloon and space missions over several decades. Additionally a new model, based on the GCR-ISO model, developed at the German Aerospace Centre (DLR) was also investigated. The differences arising in the radiation exposure by applying these models are quantified in terms of absorbed dose and dose equivalent rates that were estimated numerically using the GEANT4 Monte-Carlo framework. During certain epochs in the last decade, there are large discrepancies between the model and the measured spectra. All models exhibit weaknesses in describing the increased GCR flux that was observed in 2009-2010. The differences in the spectra, described by the models, result in considerable differences in the estimated dose quantities.

Mrigakshi, A. I.; Matthiä, D.; Berger, T.; Reitz, G.; Wimmer-Schweingruber, R. F.

2012-12-01

292

Assessment of galactic cosmic ray models  

NASA Astrophysics Data System (ADS)

Among several factors involved in the development of a manned space mission concept, the astronauts' health is a major concern that needs to be considered carefully. Galactic cosmic rays (GCRs), which mainly consist of high-energetic nuclei ranging from hydrogen to iron and beyond, pose a major radiation health risk in long-term space missions. It is therefore required to assess the radiation exposure of astronauts in order to estimate their radiation risks. This can be done either by performing direct measurements or by making computer based simulations from which the dose can be derived. A necessary prerequisite for an accurate estimation of the exposure using simulations is a reliable description of the GCR spectra. The aim of this work is to compare GCR models and to test their applicability for the exposure assessment of astronauts. To achieve this, commonly used models capable of describing both light and heavy GCR particle spectra were evaluated by investigating the model spectra for various particles over several decades. The updated Badhwar-O'Neill model published in the year 2010, CREME2009 which uses the International Standard model for GCR, CREME96 and the Burger-Usoskin model were examined. Hydrogen, helium, oxygen and iron nuclei spectra calculated by the different models are compared with measurements from various high-altitude balloon and space-borne experiments. During certain epochs in the last decade, there are large discrepancies between the GCR energy spectra described by the models and the measurements. All the models exhibit weaknesses in describing the increased GCR flux that was observed in 2009-2010.

Mrigakshi, Alankrita Isha; Matthiä, Daniel; Berger, Thomas; Reitz, Günther; Wimmer-Schweingruber, Robert F.

2012-08-01

293

An Improved Analytic Model for Microdosimeter Response  

NASA Technical Reports Server (NTRS)

An analytic model used to predict energy deposition fluctuations in a microvolume by ions through direct events is improved to include indirect delta ray events. The new model can now account for the increase in flux at low lineal energy when the ions are of very high energy. Good agreement is obtained between the calculated results and available data for laboratory ion beams. Comparison of GCR (galactic cosmic ray) flux between Shuttle TEPC (tissue equivalent proportional counter) flight data and current calculations draws a different assessment of developmental work required for the GCR transport code (HZETRN) than previously concluded.

Shinn, Judy L.; Wilson, John W.; Xapsos, Michael A.

2001-01-01

294

Modeling and Experimental Study of Forbush Effects of Galactic Cosmic Rays  

NASA Astrophysics Data System (ADS)

temporal changes of the rigidity spectrum of the sporadic and recurrent Forbush effects of galactic cosmic rays (GCR) have been studied using neutron monitors data. An attempt to find a relationship between the rigidity spectrum exponent ? of the Forbush effects (?D/D(R) ? R-? , where R is the rigidity of GCR particles) and an exponent ? of the power spectral density (PSD) of the fluctuations of the strength of the interplanetary magnetic field (IMF) (PSD ? f-? , where f is the frequency) has been made. EXPERIMENTAL DATA AND METHOD OF INVESTIGATION. An attempt to find a relationship between the rigidity spectrum exponent ? of the Forbush effects [1] (? D/D(R) ? R-? , where R is the rigidity of GCR particles) and an exponent ? of the PSD of the fluctuations of the strength of the IMF has been made. Data of neutron super monitors and the IMF's Bx , By , and Bz components have been used to study peculiarities of two great sporadic Forbush effects (9-23 July 1982 and 9-29 July 2000) and one recurrent Forbush effect of the 1-16 September 1996 (figures 1ab c). It is well known that one of the ma jor parameters for the characterizing of the Forbush effects of GCR is the rigidity spectrum of the GCR intensity variations, hereafter called the rigidity spectrum of Forbush effect (? D(R)/D(R ) = A R-? , where R is the rigidity of GCR particles and A is the power). The rigidity spectrum of the Forbush effects has been calculated using the data of neutron super monitors and the method presented, e.g. in [2,3]. There was assumed: ? D(R)/D(R) = A R-? for R?Rmax . And ? D(R)/D(R) = 0 for R>Rmax. Here Rmax is the upper limiting rigidity beyond which the Forbush effect of GCR intensity vanishes. Results of calculations of ? based on daily means of data for the sporadic Forbush effects, 9-23 July 1982 (14 stations), 9-29 July 2000 (11 stations) and for the recurrent Forbush effect of 1-16 September 1996 (7 stations) are presented in the figures 1def. RESULTS, PHYSICAL MODEL AND DISCUSSION. It is seen from the fig.1de that the rigidity spectrum of the sporadic Forbush effects are soft at the phases of the decreasing of GCR intensity, while that

Alania, Michael V.; Szabelski, J.; Wawrzynczak, A.

2003-07-01

295

Badhwar-O'Neill 2011 Galactic Cosmic Ray Model Update and Future Improvements  

NASA Technical Reports Server (NTRS)

The Badhwar-O'Neill Galactic Cosmic Ray (GCR) Model based on actual GR measurements is used by deep space mission planners for the certification of micro-electronic systems and the analysis of radiation health risks to astronauts in space missions. The BO GCR Model provides GCR flux in deep space (outside the earth's magnetosphere) for any given time from 1645 to present. The energy spectrum from 50 MeV/n-20 GeV/n is provided for ions from hydrogen to uranium. This work describes the most recent version of the BO GCR model (BO'11). BO'11 determines the GCR flux at a given time applying an empirical time delay function to past sunspot activity. We describe the GCR measurement data used in the BO'11 update - modern data from BESS, PAMELA, CAPRICE, and ACE emphasized for than the older balloon data used for the previous BO model (BO'10). We look at the GCR flux for the last 24 solar minima and show how much greater the flux was for the cycle 24 minimum in 2010. The BO'11 Model uses the traditional, steady-state Fokker-Planck differential equation to account for particle transport in the heliosphere due to diffusion, convection, and adiabatic deceleration. It assumes a radially symmetrical diffusion coefficient derived from magnetic disturbances caused by sunspots carried onward by a constant solar wind. A more complex differential equation is now being tested to account for particle transport in the heliosphere in the next generation BO model. This new model is time-dependent (no longer a steady state model). In the new model, the dynamics and anti-symmetrical features of the actual heliosphere are accounted for so empirical time delay functions will no longer be required. The new model will be capable of simulating the more subtle features of modulation - such as the Sun's polarity and modulation dependence on the gradient and curvature drift. This improvement is expected to significantly improve the fidelity of the BO GCR model. Preliminary results of its performance will be presented.

O'Neill, Pat M.; Kim, Myung-Hee Y.

2014-01-01

296

Neutron Production in the Lunar Subsurface from Galactic Cosmic Ray Nuclei  

NASA Astrophysics Data System (ADS)

The neutron production from galactic cosmic ray (GCR) protons and alpha particles in the lunar subsurface was estimated using the three-dimensional Monte Carlo simulation code PHITS, together with GCR input spectra based on the BESS measurements. The PHITS simulations of equilibrium neutron density profiles in the lunar subsurface were compared with experimental data by Apollo 17 Lunar Neutron Probe Experiment. By use of accurate spectra and nuclear interaction models, our calculations successfully reproduced the data within the experimental error at the shallower region than 300 g/cm2. However, our calculation was up to 30% higher in the deeper region.

Ota, Shuya; Sihver, Lembit; Kobayashi, Shingo; Yamashita, Naoyuki; Hasebe, Nobuyuki

2010-04-01

297

Laser Transformation Hardening of Precision V-Slide Way.  

National Technical Information Service (NTIS)

The paper presents the results of the study of the application of laser transformation hardening (LTH) on the precision slide ways and some specimens of 20, 45, GCr15, 18Cr2Ni4WA or other steels by 1KW transverse CO2 laser. It is concluded that (1) the LT...

G. Zhang Q. Yang Y. Wu

1986-01-01

298

Nuclear MHD Converter.  

National Technical Information Service (NTIS)

This work originates from the proposal MHD Compressor-Expander Conversion System Integrated with a GCR Inside a Deployable Reflector submitted by ANSALDO under PRDA RA-22-87PC90271, January 1987. The proposal concerned an innovative concept of nuclear, cl...

G. Tuninetti E. Botta C. Criscuolo P. Riscossa F. Giammanco

1989-01-01

299

[The analysis of the factors influencing the development of glucocorticoid resistance in the etiopathogenesis of severe bronchial asthma].  

PubMed

Bronchial asthma is a disease of multi - factored etiology. Current data show that multiple genes may be involved in the pathogenesis of asthma. Corticosteroids (GCS) are the most effective anti-inflammatory therapy for inflammatory disease such as bronchial asthma. There are 2 major types of GCS-resistant asthma to treatment of high doses of inhaled and oral glucocorticoids. Type I GCS-resistant asthma is cytokine-induced or acquired. Type II GCS resistance involves generalized primary cortisol resistance, which affects all tissues and is likely associated with a mutation in the GCR gene or in genes that modulate GCR function. There are clear examples of glucocorticoid gene h-GCR/NR3C1 polymorphisms that can influence responses and sensitivity to glucocorticosteroids. This article may lead to holistic the development analysis of the factors determining the progress of the glucocorticoid resistance in the severe bronchial asthma with special acknowledgement of the influence of polymorphisms of the glucocorticoid receptor gene h-GCR/NR3C1 to formation GCS resistance. PMID:21473041

Panek, Micha?; Pietras, Tadeusz; Kupry?-Lipi?ska, Izabela; Górski, Pawe?; Kuna, Piotr; Szemraj, Janusz

2010-01-01

300

Modeling a CMYK printer as an RGB printer  

Microsoft Academic Search

In CMYK output devices, many colors are reproducible by more than one combination of CMYK colorants. When a CMYK device is modeled as an RGB device, each RGB combination must produce a unique CMYK combination. Under color removal (UCR) and gray component replacement (GCR) techniques have been traditionally used to calculate these unique combinations. These techniques are simple to implement,

James Z. Chang; John C. Dalrymple

2001-01-01

301

Pathologic role of stressed-induced glucocorticoids in drug-induced liver injury in mice  

Microsoft Academic Search

We previously reported that acetaminophen (APAP)-induced liver injury (AILI) in mice is associated with a rise in serum levels of the glucocorticoid (GC), corticosterone. In the current study, we provide evidence that endogenous GC play a pathologic role in AILI. Specifically, pretreatment of mice with the GC receptor (GCR) inhibitor, RU486 (mifepristrone), protected normal but not adrenalectomized mice from AILI,

Mary Jane Masson; Lindsay A. Collins; Leah D. Carpenter; Mary L. Graf; Pauline M. Ryan; Mohammed Bourdi; Lance R. Pohl

2010-01-01

302

Benchmark solutions for the galactic ion transport equations with spatial and energy coupling  

Microsoft Academic Search

In order to anticipate future space shielding requirements, NASA has initiated an effort to formulate computational methods to simulate radiation effects in space. As part of the program, numerical transport algorithms have been developed for the deterministic Boltzman equation describing galactic cosmic ray (GCR) interactions with matter. It thus becomes necessary to assess the accuracy of proposed deterministic algorithms. For

Barry D. Ganapol

1988-01-01

303

Benchmarking Radiation Transport Codes for Space Missions  

Microsoft Academic Search

For long duration and\\/or deep space human missions, protection from severe space radiation exposure is a challenging design constraint and may be a potential limiting factor. The space radiation environment consists of galactic cosmic rays (GCR), solar particle events (SPE), trapped radiation, and includes ions of all the known elements over a very broad energy range. These ions penetrate spacecraft

Ram Tripathi; John Wilson; Larry Townsend; Tony Gabriel; Larry Pinsky; Tony Slaba

2008-01-01

304

Modulation of galactic cosmic rays during the unusual solar minimum between cycles 23 and 24  

NASA Astrophysics Data System (ADS)

During the recent solar minimum between cycles 23 and 24 (solar minimum P23/24), the intensity of galactic cosmic rays (GCR) measured at the Earth was the highest ever recorded since space age. It is the purpose of this paper to resolve the most plausible mechanism for this unusually high intensity. A GCR transport model in three-dimensional heliosphere based on a simulation of Markov stochastic process is used to find the relation of cosmic ray modulation to various transport parameters, including solar wind (SW) speed, distance of heliospheric boundary, magnitude of interplanetary magnetic field (IMF) at the Earth, tilt angle of heliospheric current sheet, and values of parallel and perpendicular diffusion coefficients. We calculate GCR proton energy spectra at the Earth for the last three solar minima P21/22, P22/23, and P23/24, with the transport parameters obtained from observations. Besides weak IMF magnitude and slow SW speed, we find that a possible low magnetic turbulence, which increases the parallel diffusion and reduces the perpendicular diffusion in the polar direction, might be an additional possible mechanism for the high GCR intensity in the solar minimum P23/24.

Zhao, L.-L.; Qin, G.; Zhang, M.; Heber, B.

2014-03-01

305

Galactic Cosmic Rays and Ion Induced Aerosol Production  

NASA Astrophysics Data System (ADS)

The effect of ions on the production of sulfate aerosol in the Earth's atmosphere has been a topic of a number of modeling studies in the recent past. These studies were able to explain new particle formation in the middle and lower troposphere, observed in field campaigns under conditions where classical binary nucleation theory does not allow for a substantial particle production. However, recent observations of massive charged clusters in the upper troposphere indicate that ions may play an important role for aerosol formation in higher atmospheric regions as well. A major source of ions in the lower and middle atmosphere are galactic cosmic rays (GCR). The ion production due to GCR and the subsequent formation of sulfuric aerosol, together with its variations in altitude and solar cycle phase, were another topic of modeling studies. However, these studies relied mainly on theoretical approaches to ion-induced nucleation, and on sparse data of ion production in the atmosphere due to GCR. We present a study of aerosol formation based on laboratory thermochemistry data of negative sulfuric acid / water clusters and on modeled ion production rates due to GCR, covering different atmospheric regions. This approach allows for results which are subject to less quantitative uncertainties than previous work, and enables us to investigate and compare the aerosol production due to binary and ion-induced nucleation in various conditions.

Kazil, J.; Lovejoy, E. R.; Desorgher, L.

2003-12-01

306

A preliminary comparison of gas core fission and inertial fusion for the space exploration initiative  

Microsoft Academic Search

Potential utilization of fission and fusion-based propulsion systems for solar system exploration is examined using a Mars mission as basis. One system employs the open cycle gas core fission reactor (GCR) as the energy source, while the other uses the fusion energy produced in an inertial Confinement Fusion (MICF) concept, to convert thermal energy into thrust. It is shown that

Terry Kammash; David L. Galbraith

1992-01-01

307

GUIDELINES FOR DETERMINATION OF LABORATORY ACCEPTABILITY FOR ANALYSIS OF VOLATILE ORGANIC POLLUTANTS COLLECTED ON TENAX GC (TRADE NAME) ADSORBENT  

EPA Science Inventory

A Technical Assistant Document (TAD) has been prepared which is intended to serve as a guide to those persons responsible for evaluating and/or selecting a laboratory to perform sampling and analysis of airborne, organic pollutants using Tenax GCR polymer and gas chromatography/m...

308

Gas Core Reactor-MHD Power System with Cascading Power Cycle  

Microsoft Academic Search

The US Department of Energy initiative Gen-IV aim is to produce an entire nuclear energy production system with next generation features for certification before 2030. A Generation 4 capable system must have superior sustainability, safety and reliability, and economic cost advantages in comparison with third generation light water reactors. A gas core reactor (GCR) with magnetohydrodynamic (MHD) power converter and

Blair M. Smith; Samim Anghaie; Travis W. Knight

2002-01-01

309

Plant regeneration from leaf protoplasts of Brassica oleracea var. italica CV Green Comet broccoli  

Microsoft Academic Search

A procedure is described for regeneration of plants from leaf protoplasts of the hybrid broccoli cultivar, Green Comet (Brassica oleracea var italica). The totipotency of protoplasts isolated from plants regenerated from hypocotyl explants (GCR) was greater than that of protoplasts from plants grown directly from seed (GC). Using medium B developed by Pelletier et al (1983), division efficiencies greater than

D. Robertson; E. D. Earle

1986-01-01

310

The Projection of Space Radiation Environments with a Solar Cycle Statistical Model  

NASA Technical Reports Server (NTRS)

A solar cycle statistical model has been developed to project sunspot numbers which represent the variations in the space radiation environment. The resultant projection of sunspot numbers in near future were coupled to space-related quantities of interest in radiation protection, such as the galactic cosmic radiation (GCR) deceleration potential (f) and the mean occurrence frequency of solar particle event (SPE). Future GCR fluxes have been derived from a predictive model, in which GCR temporal dependence represented by f was derived from GCR flux and ground-based Climax neutron monitor rate measurements over the last four decades. Results showed that the point dose equivalent inside a typical spacecraft in interplanetary radiation fields was influenced by solar modulation up to a factor of three. One important characteristic of sporadic SPEs is their mean frequency of occurrence, which is dependent on solar activity. Projections of future mean frequency of SPE occurrence were estimated from a power law function of sunspot number. Furthermore, the cumulative probabilities of SPE during short-period missions were defined with the continuous database of proton fluences of SPE. The analytic representation of energy spectra of SPE was constructed by the Weibull distribution for different event sizes. The representative exposure level at each event size was estimated for the guideline of protection systems for astronauts during future space exploration missions.

Kim, Myung-Hee; Cucinotta, Francis A.; Wilson, John W.

2006-01-01

311

Grammatical Consciousness-Raising and the Lexicon.  

ERIC Educational Resources Information Center

A role is proposed for the lexicon in the grammatical consciousness-raising (GCR) framework for second language teaching outlined by W. Rutherford and M. Sharwood Smith (1987, 1988). First, a lexical framework that offers a series of questions to help teachers discover the relevant semantic and pragmatic information associated with grammatical…

Bland, Susan Kesner

312

How safe is safe enough? Radiation risk for a human mission to Mars.  

PubMed

Astronauts on a mission to Mars would be exposed for up to 3 years to galactic cosmic rays (GCR)--made up of high-energy protons and high charge (Z) and energy (E) (HZE) nuclei. GCR exposure rate increases about three times as spacecraft venture out of Earth orbit into deep space where protection of the Earth's magnetosphere and solid body are lost. NASA's radiation standard limits astronaut exposures to a 3% risk of exposure induced death (REID) at the upper 95% confidence interval (CI) of the risk estimate. Fatal cancer risk has been considered the dominant risk for GCR, however recent epidemiological analysis of radiation risks for circulatory diseases allow for predictions of REID for circulatory diseases to be included with cancer risk predictions for space missions. Using NASA's models of risks and uncertainties, we predicted that central estimates for radiation induced mortality and morbidity could exceed 5% and 10% with upper 95% CI near 10% and 20%, respectively for a Mars mission. Additional risks to the central nervous system (CNS) and qualitative differences in the biological effects of GCR compared to terrestrial radiation may significantly increase these estimates, and will require new knowledge to evaluate. PMID:24146746

Cucinotta, Francis A; Kim, Myung-Hee Y; Chappell, Lori J; Huff, Janice L

2013-01-01

313

Radiation dosimetry for high LET particles in low Earth orbit  

Microsoft Academic Search

Research indicates that the impact to human tissues from radiation exposure is strongly related to the LET (linear energy transfer) of the particles and particles with high LET (?5KeV\\/?m water) dominate the damage. High LET radiation in LEO (low Earth orbit) is composed mainly of galactic cosmic rays (GCR), solar energetic particles, particles trapped in the SAA (South Atlantic Anomaly),

D. Zhou; D. O’Sullivan; E. Semones; N. Zapp; S. Johnson; M. Weyland

2008-01-01

314

Energetic particle environment in near — Earth orbit  

Microsoft Academic Search

The hazard of exposure to high doses of ionizing radiation is one of the primary concerns of extended manned space missions and a continuous threat for the numerous spacecraft in operation today. In the near - Earth environment the main sources of radiation are solar energetic particles (SEP), galactic cosmic rays (GCR), and geomagnetically trapped particles, predominantly protons and electrons.

B. Klecker

1996-01-01

315

LET distribution measurement with a new real-time radiation monitoring device-III onboard the Space Shuttle STS-84  

NASA Astrophysics Data System (ADS)

A new type of Real-time Radiation Monitoring Device, RRMD-III, consisting of three double-sided silicon strip detectors (DSSDs) has been constructed and used onboard the Space Shuttle mission STS-84. The Space Shuttle cruised at an altitude of /300-/400 km and an inclination angle of /51.6° for /221.3 h. RRMD-III succeeded in measuring the linear energy transfer (LET) distribution over the range of /0.2-600keV/?m for 178h. The obtained LET distribution of particles was investigated in detail by classifying it into galactic cosmic ray (GCR) particles and trapped protons in the South Atlantic Anomaly (SAA) region. The result shows that GCR particles contribute /60% to the total dose equivalent. The total absorbed dose rate during the mission was 0.516mGy/day, the effective quality factor was 1.81 by ICRP-Pub.26, and the dose equivalent rate was 0.935mSv/day. The average absorbed dose rates are 0.120?Gy/min for GCR particles and 4.80?Gy/min for trapped protons. The effective quality factors are /3.16 for GCR particles and /1.19 for trapped protons. RRMD-III data were also compared with the data of the tissue equivalent proportional counter (TEPC), proving that RRMD-III is a reliable device for deriving the true-LET distribution in real time for evaluating space radiation.

Sakaguchi, T.; Doke, T.; Hasebe, N.; Hayashi, T.; Kashiwagi, T.; Kikuchi, J.; Kono, S.; Nagaoka, S.; Nakano, T.; Takagi, T.; Takahashi, K.; Takahashi, S.

1999-11-01

316

Development of Liquid-Vapor Core Reactors with MHD Generator for Space Power and Propulsion Applications  

Microsoft Academic Search

Any reactor that utilizes fuel consisting of a fissile material in a gaseous state may be referred to as a gaseous core reactor (GCR). Studies on GCRs have primarily been limited to the conceptual phase, mostly due to budget cuts and program cancellations in the early 1970's. A few scientific experiments have been conducted on candidate concepts, primarily of static

Samim Anghaie

2002-01-01

317

Assessing the Response of Aerosol Nucleation, Cloud Parameters, and Radiative Forcing Over Oceans to Variations in Galactic Cosmic Ray Intensity  

NASA Astrophysics Data System (ADS)

Atmospheric ions are likely aerosol precursors because they greatly stabilize small clusters with respect to evaporation. A source of atmospheric ions are galactic cosmic rays (GCR). The variation of GCR intensity over the decadal solar cycle might thus appear in aerosol and cloud condensation nuclei concentrations. The resulting variation of cloud droplet size distributions and concentrations, and hence of cloud albedo and cloud lifetime would bear upon radiative forcing of the troposphere. We analyze the response of aerosol production over the oceans to the variation of GCR intensity over the decadal solar cycle using results from a model of neutral and charged H2O/H2SO_4 aerosol microphysics. Our model employs laboratory thermodynamics for the growth and evaporation of charged, and modified liquid drop thermodynamics for the growth and evaporation of neutral H2O/H2SO_4 clusters, respectively. Input data are taken from a model of galactic cosmic rays in the atmosphere, and from global chemistry and transport models. We give an upper limit to the possible response of cloud albedo and cloud amount to variations in GCR intensity in the course of the decadal solar cycle via the first and second indirect aerosol effects, and to the consequential response of tropospheric radiative forcing. Uncertainties arising from our approach are discussed.

Kazil, J.; Lovejoy, E. R.; Barth, M. C.; O'Brien, K.

2005-12-01

318

Solar irradiance, cosmic rays and cloudiness over daily timescales  

NASA Astrophysics Data System (ADS)

Although over centennial and greater timescales solar variability may be one of the most influential climate forcing agents, the extent to which solar activity influences climate over shorter time periods is poorly understood. If a link exists between solar activity and climate, it is likely via a mechanism connected to one (or a combination) of the following parameters: total solar irradiance (TSI), ultraviolet (UV) spectral irradiance, or the galactic cosmic ray (GCR) flux. We present an analysis based around a superposed epoch (composite) approach focusing on the largest TSI increases and decreases (the latter occurring in both the presence and absence of appreciable GCR reductions) over daily timescales. Using these composites we test for the presence of a robust link between solar activity and cloud cover over large areas of the globe using rigorous statistical techniques. We find no evidence that widespread variations in cloud cover at any tropospheric level are significantly associated with changes in the TSI, GCR or UV flux, and further conclude that TSI or UV changes occurring during reductions in the GCR flux are not masking a solar-cloud response. However, we note the detectability of any potential links is strongly constrained by cloud variability.

Laken, Benjamin A.; ?alogovi?, Jasa

2011-12-01

319

Space Radiation Transport Codes: A Comparative Study for Galactic Cosmic Rays Environment  

NASA Astrophysics Data System (ADS)

For long duration and/or deep space human missions, protection from severe space radiation exposure is a challenging design constraint and may be a potential limiting factor. The space radiation environment consists of galactic cosmic rays (GCR), solar particle events (SPE), trapped radiation, and includes ions of all the known elements over a very broad energy range. These ions penetrate spacecraft materials producing nuclear fragments and secondary particles that damage biological tissues, microelectronic devices, and materials. In deep space missions, where the Earth's magnetic field does not provide protection from space radiation, the GCR environment is significantly enhanced due to the absence of geomagnetic cut-off and is a major component of radiation exposure. Accurate risk assessments critically depend on the accuracy of the input information as well as radiation transport codes used, and so systematic verification of codes is necessary. In this study, comparisons are made between the deterministic code HZETRN2006 and the Monte Carlo codes HETC-HEDS and FLUKA for an aluminum shield followed by a water target exposed to the 1977 solar minimum GCR spectrum. Interaction and transport of high charge ions present in GCR radiation environment provide a more stringent constraint in the comparison of the codes. Dose, dose equivalent and flux spectra are compared; details of the comparisons will be discussed, and conclusions will be drawn for future directions.

Tripathi, Ram; Wilson, John W.; Townsend, Lawrence W.; Gabriel, Tony; Pinsky, Lawrence S.; Slaba, Tony

320

The effects of irradiation on the magnetic properties of rock and synthetic samples  

Microsoft Academic Search

Irradiations in space, by solar wind (SW), solar cosmic rays (SCR) (i.e., solar-flare-associated particles or solar energetic particles) and galactic cosmic rays (GCR) - the main source of space weathering of the solid Solar System bodies - may result in changes in magnetic properties of extraterrestrial materials, thus complicating the interpretation of the magnetism of meteorites, micrometeorites and lunar samples.

N. S. Bezaeva; P. Rochette; J. Gattacceca; J. Duprat; G. Rizza; P. Vernazza; V. I. Trukhin

2009-01-01

321

Analyses of Impacts of Bottom Sediments from Grand Calumet River and Indiana Harbor Canal on Water Quality.  

National Technical Information Service (NTIS)

The influence of polluted bottom sediments on the quality of water in the Grand Calumet River/Indiana Harbor Canal (GCR/IHC) was investigated. The approach used consisted of obtaining and analyzing existing information on sediment-water interactions and t...

D. Gunnison D. E. Averett J. L. Martin J. M. Brannon R. L. Chen

1989-01-01

322

Level of glucocorticoid receptor mRNA expression in iris tissue and postoperative ocular inflammation in patients with uveitis  

Microsoft Academic Search

Background. . Glucocorticoids (GC) are widely used to treat uveitis, but their efficacy is known to vary substantially among patients. In this retrospective preliminary study, we measured the level of GC receptor (GCR) expression in ocular tissue taken from uveitis patients during cataract surgery as an indicator of their sensitivity to GC, divided the patients into comparatively high- and low-sensitivity

Takao Tanaka; Naoyuki Yamakawa; Masahiko Usui

2003-01-01

323

Mars surface radiation exposure for solar maximum conditions and 1989 solar proton events  

NASA Technical Reports Server (NTRS)

The Langley heavy-ion/nucleon transport code, HZETRN, and the high-energy nucleon transport code, BRYNTRN, are used to predict the propagation of galactic cosmic rays (GCR's) and solar flare protons through the carbon dioxide atmosphere of Mars. Particle fluences and the resulting doses are estimated on the surface of Mars for GCR's during solar maximum conditions and the Aug., Sep., and Oct. 1989 solar proton events. These results extend previously calculated surface estimates for GCR's at solar minimum conditions and the Feb. 1956, Nov. 1960, and Aug. 1972 solar proton events. Surface doses are estimated with both a low-density and a high-density carbon dioxide model of the atmosphere for altitudes of 0, 4, 8, and 12 km above the surface. A solar modulation function is incorporated to estimate the GCR dose variation between solar minimum and maximum conditions over the 11-year solar cycle. By using current Mars mission scenarios, doses to the skin, eye, and blood-forming organs are predicted for short- and long-duration stay times on the Martian surface throughout the solar cycle.

Simonsen, Lisa C.; Nealy, John E.

1992-01-01

324

Predictors of Satisfaction in Geographically Close and Long-Distance Relationships  

ERIC Educational Resources Information Center

In this study, the authors examined geographically close (GCRs) and long-distance (LDRs) romantic relationship satisfaction as explained by insecure attachment, self-disclosure, gossip, and idealization. After college student participants (N = 536) completed a Web survey, structural equation modeling (SEM) multigroup analysis revealed that the GCR

Lee, Ji-yeon; Pistole, M. Carole

2012-01-01

325

Commitment Predictors: Long-Distance versus Geographically Close Relationships  

ERIC Educational Resources Information Center

In this web-based study, the authors examined long-distance relationships (LDRs) and geographically close relationships (GCRs). Two hierarchical multiple regressions (N = 138) indicated that attachment predicted LDR and GCR commitment in Step 1. Final equations indicated that high satisfaction and investments predicted LDR commitment, whereas low…

Pistole, M. Carole; Roberts, Amber; Mosko, Jonathan E.

2010-01-01

326

Participation of direct drive Wind Turbine to the grid ancillary services using a Flywheel Energy Storage System  

Microsoft Academic Search

Renewable energy sources have achieved increasing levels of penetration in recent years. Therefore, the impact of those sources on the power system is becoming greater, due to their intermittent source. The current tendency is to remain the Wind Turbine (WT) connected to the grid during voltage dip or frequency variation according to the grid connection requirements (GCR). This paper proposes

M. Khaterchi; J. Belhadj; M. Elleuch

2010-01-01

327

Identification of quantitative trait loci associated with rice eating quality traits using a population of recombinant inbred lines derived from a cross between two temperate japonica cultivars.  

PubMed

Improved eating quality is a major breeding target in japonica rice due to market demand. In this study, we performed genetic analysis to identify quantitative trait loci (QTLs) that control rice eating quality traits using 192 recombinant inbred lines (RILs) derived from a cross between two japonica cultivars, 'Suweon365' and 'Chucheongbyeo'. We evaluated the stickiness (ST) and overall evaluation (OE) of cooked rice using a sensory test, the glossiness of cooked rice (GCR) using a Toyo-taste meter, and measured the amylose content (AC), protein content (PC), alkali digestion value (ADV), and days to heading (DH) of the RILs in the years 2006 and 2007. Our analysis revealed 21 QTLs on chromosomes 1, 4, 6, 7, 8, and 11. QTLs on chromosomes 6, 7, and 8 were detected for three traits related to eating quality in both years. QTLs for ST and OE were identified by a sensory test in the same region of the QTLs for AC, PC, ADV, GCR and DH on chromosome 8. QTL effects on the GCR were verified using QTL-NILs (near-isogenic lines) of BC(3)F(4-6) in the Suweon365 background, a low eating quality variety, and some BC(1)F(3) lines. Chucheongbyeo alleles at QTLs on chromosomes 7 and 8 increased the GCR in the NILs and backcrossed lines. The QTLs identified by our analysis will be applicable to future marker-assisted selection (MAS) strategies for improving the eating quality of japonica rice. PMID:21360198

Kwon, Soon-Wook; Cho, Young-Chan; Lee, Jeong-Heui; Suh, Jung-Pil; Kim, Jeong-Ju; Kim, Myeong-Ki; Choi, Im-Soo; Hwang, Hung-Goo; Koh, Hee-Jong; Kim, Yeon-Gyu

2011-05-01

328

Managing Lunar and Mars Mission Radiation Risks. Part 1; Cancer Risks, Uncertainties, and Shielding Effectiveness  

NASA Technical Reports Server (NTRS)

This document addresses calculations of probability distribution functions (PDFs) representing uncertainties in projecting fatal cancer risk from galactic cosmic rays (GCR) and solar particle events (SPEs). PDFs are used to test the effectiveness of potential radiation shielding approaches. Monte-Carlo techniques are used to propagate uncertainties in risk coefficients determined from epidemiology data, dose and dose-rate reduction factors, quality factors, and physics models of radiation environments. Competing mortality risks and functional correlations in radiation quality factor uncertainties are treated in the calculations. The cancer risk uncertainty is about four-fold for lunar and Mars mission risk projections. For short-stay lunar missins (<180 d), SPEs present the most significant risk, but one effectively mitigated by shielding. For long-duration (>180 d) lunar or Mars missions, GCR risks may exceed radiation risk limits. While shielding materials are marginally effective in reducing GCR cancer risks because of the penetrating nature of GCR and secondary radiation produced in tissue by relativisitc particles, polyethylene or carbon composite shielding cannot be shown to significantly reduce risk compared to aluminum shielding. Therefore, improving our knowledge of space radiobiology to narrow uncertainties that lead to wide PDFs is the best approach to ensure radiation protection goals are met for space exploration.

Cucinotta, Francis A.; Kim, Myung-Hee Y.; Ren, Lei

2005-01-01

329

End-To-End Risk Assesment: From Genes and Protein to Acceptable Radiation Risks for Mars Exploration  

Microsoft Academic Search

The human exploration of Mars will impose unavoidable health risks from galactic cosmic rays (GCR) and possibly solar particle events (SPE). It is the goal of NASA's Space Radiation Health Program to develop the capability to predict health risks with significant accuracy to ensure that risks are well below acceptable levels and to allow for mitigation approaches to be effective

Francis A. Cucinotta; Walter Schimmerling

2000-01-01

330

Nuclear Physics on Critical Path for Space Missions  

Microsoft Academic Search

Protection from hazards of space radiation has been identified as one of the five NASA's critical areas for human space flights. The space radiation environment consists of galactic cosmic rays (GCR), solar particle events (SPE), trapped radiation, and includes ions of all the known elements over a very broad energy range. These ions penetrate spacecraft materials producing nuclear fragments and

Ram Tripathi

2007-01-01

331

Neutron production in the lunar subsurface from alpha particles in galactic cosmic rays  

NASA Astrophysics Data System (ADS)

The neutron production from alpha particles in galactic cosmic rays (GCR) in the lunar subsurface has not been estimated with reliable precision despite its importance for lunar nuclear spectroscopy and space dosimetry. Here, we report our estimation of neutron production from GCR nuclei (protons and alpha particles) with the Particle and Heavy Ion Transport code System (PHITS), which includes several heavy ion interaction models. PHITS simulations of the equilibrium neutron density profiles in the lunar subsurface are compared with experimental data obtained in the Apollo 17 Lunar Neutron Probe Experiment. Our calculations successfully reproduced the data within an experimental error of 15%. Our estimation of neutron production from GCR nuclei, estimated by scaling that from protons by a factor of 1.27, is in good agreement within an error of 1% with the calculations using two different alpha particle interaction models in PHITS during a period of average activity of the solar cycle. However, we show that the factor depends on the incident GCR spectrum model used in the simulation. Therefore, we conclude that the use of heavy ion interaction models is important for estimating neutron production in the lunar subsurface.

Ota, S.; Kobayashi, S.; Sihver, L.; Yamashita, N.; Hasebe, N.

2011-01-01

332

Probing the small-scale structure of the interplanetary medium with high time resolution galactic cosmic ray observations  

NASA Astrophysics Data System (ADS)

Galactic cosmic rays (GCRs) are relativistic charged particles that fill interplanetary and interstellar space. The Sun's magnetic field, carried radially outward by the solar wind (collectively called the interplanetary medium or IPM), is the dominant modulator of GCR fluxes near Earth. GCR variations can uncover IPM structure beyond what single-point IPM measurements reveal. While such research in the past has been successful on larger scales, little work has considered how the IPM affects GCRs on small scales (scales on the order of at most an hour in time or gigameters in space). This dissertation represents the first use of GCR observations to explore the nature of small-scale structure in the IPM, an area of active study. To begin, I test the validity of an important traditional model based on low time resolution observations. This model describes how interplanetary coronal mass ejections (ICMEs), their shocks, and their sheaths create two-step Forbush decreases (Fds) in GCR flux ( Forbush , 1937). I analyze 82 Fds from 1998 to 2006 and discover that the model is too idealized to account for the majority of Fds. Small-scale structure in the sheath of ICMEs appears to be important for creating a variety of time-profiles, instead of only the two steps predicted by the model. Next, I use space-based, high time resolution GCR data to investigate on even smaller scales how ICME sheath structure affects cosmic rays. Because the spacecraft instruments were not designed to detect GCRs, I first show that the space-based data are reliable. In three of the five observed Fds, planar magnetic structures within the ICME sheaths appear to have contributed to the initiation of the decreases. Finally, I explore thirty instances of a newly discovered phenomenon: small-scale local maxima in the GCR flux that occur within ICME sheaths during the initial stages of Fds. I discover that magnetic structure, not turbulence, in ICME sheaths is responsible for the majority of these maxima. This dissertation highlights the important contribution that high time resolution GCR data can make to understanding the nature of small-scale structure in the IPM.

Jordan, Andrew P.

333

The Average Quality Factors by TEPC for Charged Particles  

NASA Technical Reports Server (NTRS)

The quality factor used in radiation protection is defined as a function of LET, Q(sub ave)(LET). However, tissue equivalent proportional counters (TEPC) measure the average quality factors as a function of lineal energy (y), Q(sub ave)(Y). A model of the TEPC response for charged particles considers energy deposition as a function of impact parameter from the ion s path to the volume, and describes the escape of energy out of sensitive volume by delta-rays and the entry of delta rays from the high-density wall into the low-density gas-volume. A common goal for operational detectors is to measure the average radiation quality to within accuracy of 25%. Using our TEPC response model and the NASA space radiation transport model we show that this accuracy is obtained by a properly calibrated TEPC. However, when the individual contributions from trapped protons and galactic cosmic rays (GCR) are considered; the average quality factor obtained by TEPC is overestimated for trapped protons and underestimated for GCR by about 30%, i.e., a compensating error. Using TEPC's values for trapped protons for Q(sub ave)(y), we obtained average quality factors in the 2.07-2.32 range. However, Q(sub ave)(LET) ranges from 1.5-1.65 as spacecraft shielding depth increases. The average quality factors for trapped protons on STS-89 demonstrate that the model of the TEPC response is in good agreement with flight TEPC data for Q(sub ave)(y), and thus Q(sub ave)(LET) for trapped protons is overestimated by TEPC. Preliminary comparisons for the complete GCR spectra show that Q(sub ave)(LET) for GCR is approximately 3.2-4.1, while TEPC measures 2.9-3.4 for QQ(sub ave)(y), indicating that QQ(sub ave)(LET) for GCR is underestimated by TEPC.

Kim, Myung-Hee Y.; Nikjoo, Hooshang; Cucinotta, Francis A.

2004-01-01

334

What is the Outer Boundary of Galactic Cosmic-Ray Modulation by the Heliosphere?  

NASA Astrophysics Data System (ADS)

As the Voyager spacecraft move into the outer heliosheath, the question of the proper outer boundary conditions for galactic and anomalous cosmic rays (GCR and ACR) assumes greater importance. Conventionally, the boundary has been taken to be the heliopause, the boundary region between the interstellar plasma and plasma of solar origin. At this boundary, workers have assumed that the interstellar medium allows the ACR escape freely from the heliosheath and the GCR take on their unmodified galactic spectrum. In reality, the transport beyond the heliopause is not completely free. The interstellar medium is turbulent, albeit on large scales, and the transport there is diffusive, as well, but with quite large diffusion coefficients. Jokipii (2001) and Scherer, etal (2012) have looked at this problem. Jokipii pointed out that since the interstellar diffusion coefficient for few-hundred-MeV cosmic rays is about 10^{28} cm^2/sec, compared with le 10^{23} cm^2/sec in the outer heliosheath, there should be a very small effect, whereas Scherer, etal used a numerical simulation to conclude a significant effect on GCR. We report here a further study of the treatment of GCR boundaries, using a model which incorporates a termination shock (as opposed to Scherer, etal, who had no termination shock). Our conclusions differ from those of Scherer, et al, in that we find that the spectrum of GCR, at the heliopause differs very little from that at infinity. Possible reasons for this discrepancy will be discussed. Jokipii, J. R., COSPAR Colloquia Series 11, pg 53, Ed K. Scherer etal,2001. Scherer, etal, Astrophys. J., 735, 128, 2012.

Jokipii, J. R.; Kota, J.

2012-12-01

335

Voyager Observations of Cosmic Rays in the Heliosheath  

NASA Astrophysics Data System (ADS)

Since crossing the termination shock in 2004.95 (94AU 36°N), Voyager 1 has penetrated some 24 AU into the heliosheath over a period that now extends from near solar maximum conditions to the onset of the cycle 24 modulation at 1AU in ~ 2010. Voyager 2 entered the heliosheath in 2007.66 (83.7 AU, 27.5°S). Over the period 2006.0-2011.5 the V1/V2 265MeV/n galactic cosmic ray (GCR) He has increased at an average rate of 6.3% /year with an instanteous radial gradient of 0.2 ± 0.2%/AU. The rate of increase of 265 MeV/n H is 14%/year and 10 MeV GCR electrons increased at 55%/year. While the GCR intensities were increasing, the 15 MeV/n and 43 MeV/n ACR He at V1 began a slow decrease in 2009 that is becoming moderately steeper with time suggesting the spacecraft may be entering the region of higher magnetic fields expected near the heliopause. In 2011 the V1 GCR carbon spectra between 20 and 80 MeV/n has a slope of 1 as would be expected if the heliosheath functions as a long term storage region for GCRs with occasional forays into the region of the supersonic solar wind where they experience adiabatic energy losses. An alternate interpretation would be that their low-energy local interstellar spectrum is quite different from what was expected. Heliosheath transient increases are observed at the Voyagers, generally involving GCR ions and electrons and ACRs and which can persist for almost a year. The trigger for these events is not known at this time. The Voyager observations are establishing that at energies below ~ 1 GeV, the heliosheath is a vital, complex part of the cosmic ray dynamics in our solar system.

McDonald, F. B.; Webber, W. R.; Stone, E. C.; Cummings, A. C.; Heikkila, B.; Lal, N.

2011-12-01

336

Simulation and Comparison of Martian Surface Ionization Radiation  

NASA Astrophysics Data System (ADS)

The spectrum of energetic particle radiation and corresponding doses at the surface of Mars is being characterized by the Radiation Assessment Detector (RAD), one of ten science instruments on the Mars Science Laboratory (MSL) Curiosity Rover. The time series of dose rate for the first 300 Sols after landing on Mars on August 6, 2012 is presented here. For the comparison to RAD measurements of dose rate, Martian surface ionization radiation is simulated by utilizing observed space quantities. The GCR primary radiation spectrum is calculated by using the Badhwar-O'Neill 2011 (BO11) galactic cosmic ray (GCR) model, which has been developed by utilizing all balloon and satellite GCR measurements since 1955 and the newer 1997-2012 Advanced Composition Explorer (ACE) measurements. In the BO11 model, solar modulation of the GCR primary radiation spectrum is described in terms of the international smoothed sunspot number and a time delay function. For the transport of the impingent GCR primary radiation through Mars atmosphere, a vertical distribution of atmospheric thickness at each elevation is calculated using the vertical profiles of atmospheric temperature and pressure made by Mars Global Surveyor measurements. At Gale Crater in the southern hemisphere, the seasonal variation of atmospheric thickness is accounted for the daily atmospheric pressure measurements of the MSL Rover Environmental Monitoring Station (REMS) by using low- and high-density models for cool- and warm-season, respectively. The spherically distributed atmospheric distance is traced along the slant path, and the resultant directional shielding by Martian atmosphere is coupled with Curiosity vehicle for dose estimates. We present predictions of dose rate and comparison to the RAD measurements. The simulation agrees to within +-20% with the RAD measurements showing clearly the variation of dose rate by heliospheric conditions, and presenting the sensitivity of dose rate by atmospheric pressure, which has been found from the RAD experiments and driven by thermal tides on Martian surface.

Kim, M. Y.; Zeitlin, C. J.; Hassler, D.; Cucinotta, F.

2013-12-01

337

Simulation and Comparison of Martian Surface Ionization Radiation  

NASA Technical Reports Server (NTRS)

The spectrum of energetic particle radiation and corresponding doses at the surface of Mars is being characterized by the Radiation Assessment Detector (RAD), one of ten science instruments on the Mars Science Laboratory (MSL) Curiosity Rover. The time series of dose rate for the first 300 Sols after landing on Mars on August 6, 2012 is presented here. For the comparison to RAD measurements of dose rate, Martian surface ionization radiation is simulated by utilizing observed space quantities. The GCR primary radiation spectrum is calculated by using the Badhwar-O'Neill 2011 (BO11) galactic cosmic ray (GCR) model, which has been developed by utilizing all balloon and satellite GCR measurements since 1955 and the newer 1997-2012 Advanced Composition Explorer (ACE) measurements. In the BO11 model, solar modulation of the GCR primary radiation spectrum is described in terms of the international smoothed sunspot number and a time delay function. For the transport of the impingent GCR primary radiation through Mars atmosphere, a vertical distribution of atmospheric thickness at each elevation is calculated using the vertical profiles of atmospheric temperature and pressure made by Mars Global Surveyor measurements. At Gale Crater in the southern hemisphere, the seasonal variation of atmospheric thickness is accounted for the daily atmospheric pressure measurements of the MSL Rover Environmental Monitoring Station (REMS) by using low- and high-density models for cool- and warm-season, respectively. The spherically distributed atmospheric distance is traced along the slant path, and the resultant directional shielding by Martian atmosphere is coupled with Curiosity vehicle for dose estimates. We present predictions of dose rate and comparison to the RAD measurements. The simulation agrees to within +/- 20% with the RAD measurements showing clearly the variation of dose rate by heliospheric conditions, and presenting the sensitivity of dose rate by atmospheric pressure, which has been found from the RAD experiments and driven by thermal tides on Martian surface.

Kim, Myung-Hee Y.; Zeitlin, Cary; Hassler, Donald M.; Cucinotta, Francis A.

2013-01-01

338

A field assessment of long-term laboratory sediment toxicity tests with the amphipod Hyalella azteca  

USGS Publications Warehouse

Response of the amphipod Hyalella azteca exposed to contaminated sediments for 10 to 42 d in laboratory toxicity tests was compared to responses observed in controlled three-month invertebrate colonization exposures conducted in a pond. Sediments evaluated included a sediment spiked with dichlorodiphenyldichloroethane (DDD) or dilutions of a field sediment collected from the Grand Calumet River (GCR) in Indiana (USA) (contaminated with organic compounds and metals). Consistent effects were observed at the highest exposure concentrations (400 ??g DDD/goc [DDD concentrations normalized to grams of organic carbon (goc) in sedimentl or 4% GCR sediment) on survival, length, and reproduction of amphipods in the laboratory and on abundance of invertebrates colonizing sediments in the field. Effect concentrations for DDD observed for 10-d length and 42-d reproduction of amphipods (e.g., chronic value [ChV] of 66 ??g DDD/goc and 25% inhibition concentration [IC25] of 68 ??g DDD/goc for reproduction) were similar to the lowest effect concentrations for DDD measured on invertebrates colonizing sediment the field. Effect concentrations for GCR sediment on 28-d survival and length and 42-d reproduction and length of amphipods (i.e., ChVs of 0.20-0.66% GCR sediment) provided more conservative effect concentrations compared to 10-d survival or length of amphipods in the laboratory or the response of invertebrates colonizing sediment in the field (e.g., ChVs of 2.2% GCR sediment). Results of this study indicate that use of chronic laboratory toxicity tests with H. azteca and benthic colonization studies should be used to provide conservative estimates of impacts on benthic communities exposed to contaminated sediments. Bioaccumulation of DDD by oligochaetes colonizing the DDD-spiked sediment was similar to results of laboratory sediment tests previously conducted with the oligochaete Lumbriculus variegates, confirming that laboratory exposures can be used to estimate bioaccumulation by oligochaetes exposed in the field. ?? 2005 SETAC.

Ingersoll, C. G.; Wang, N.; Hayward, J. M. R.; Jones, J. R.; Jones, S. B.; Ireland, D. S.

2005-01-01

339

Galactic and Anomalous Cosmic Rays at 1 AU During the Recent Unusual Solar Minimum (Invited)  

NASA Astrophysics Data System (ADS)

Anomalous cosmic ray (ACR) intensities at 1 AU at solar minimum have generally tracked galactic cosmic ray (GCR) intensities such as those measured by neutron monitors, albeit with differences between solar polarity cycles. Throughout the present A<0 cycle ACR intensities have been consistently a factor of 3-4 lower than expected from scaling neutron monitor rates during the last A>0 cycle, similar to what was observed during the last A<0 period in the mid-1980's. Although the present solar minimum was deep and long-lasting with very low sunspot numbers and no major solar particle events, peak ACR intensities just barely reached their last A<0 levels. Meanwhile, GCR intensities (neutron monitor rates) were at the highest levels recorded during the last 50 years, indicating that these particles had easier access to the inner heliosphere than ACRs. During A<0 cycles particles preferentially drift inward along the heliospheric current sheet (HCS), and the HCS tilt angle dropped much more slowly this cycle than it did during the previous two cycles. Using neutron monitor data along with ACR and GCR measurements from the Advanced Composition Explorer spacecraft, we find that for a given HCS tilt angle both ACR and GCR intensities were actually much higher this cycle than they were during the last A<0 cycle. Evidently there was less overall modulation, but ACRs were more sensitive to the larger tilt of the HCS than GCRs, perhaps because of the latitudinal distribution of ACRs at their source. The HCS tilt angle increased abruptly in late 2009, and by early 2010 both ACR and GCR intensities showed dramatic decreases, apparently marking the end of solar minimum modulation conditions for this cycle. We present measurements of ACR and GCR intensities at 1 AU throughout the solar cycle and discuss possible explanations for the different behavior between the present A<0 epoch and the previous one. This work was supported by NASA grants NNX08AI11G and NNX10AE45G.

Leske, R. A.; Cummings, A. C.; Mewaldt, R. A.; Stone, E. C.

2010-12-01

340

An analytical model for the prediction of a micro-dosimeter response function  

NASA Astrophysics Data System (ADS)

A rapid analytical procedure for the prediction of a micro-dosimeter response function in Low Earth Orbit (LEO), correlated with the Space Transportation System (STS, shuttle) Tissue Equivalent Proportional Counter (TEPC) measurements is presented. The analytical model takes into consideration the energy loss straggling and chord length distribution of the detector, and is capable of predicting energy deposition fluctuations in a cylindrical micro-volume of arbitrary aspect ratio (height/diameter) by incoming ions through both direct and indirect (? rays) events. At any designated (ray traced) target point within the vehicle, the model as input accepts the differential flux spectrum of Galactic Cosmic Rays (GCR) and/or trapped protons at LEO. On a desktop PC, the response function of TEPC for each ion in the GCR/trapped field is computed at the average rate of 30 seconds/ion. The ionizing radiation environment at LEO is represented by O'Neill's GCR model (2004), covering charge particles in the 1?Z?28 range. O'Neill's free space GCR model is coupled with the Langley Research Center (LaRC) cutoff model with angular dependency compensation to compute the transmission coefficient at LEO. The trapped proton environment is represented by a LaRC developed time dependent procedure which couples the AP8min/AP8max, Deep River Neutron Monitor (DRNM) and F10.7 solar radio frequency measurements. The albedo neutron environment is represented by the extrapolation of the Atmospheric Ionizing Radiation (AIR) measurements. The charged particle transport calculations correlated with STS 56, 51, 110 and 114 flights are accomplished by using the most recent version (2005) of LaRC's deterministic ionized particle transport code High charge (Z) and Energy TRaNsport (HZETRN). Herein, we present the correlations between the TEPC model predictions (response function) and TEPC measured differential/integral spectra in the lineal energy (y) domain for both GCR and trapped protons, with the conclusion that the model correctly accounts for the increase in flux at low y values where energetic ions are the primary contributor. We further discuss that even with the incorporation of angular dependency in the cutoffs, comparison of the GCR differential/integral flux in the y domain between STS 56, 51, 110 and 114 TEPC measured data and current calculations indicates that there still exists an underestimation by the simulations (model) at low to mid range y values. This underestimation is argued to be partly related the exclusion of the secondary pion and kaon particle production from the current version of HZETRN.

Badavi, Francis; Michael, Michael; Wilson, John W.

341

An Analytical Model for the Prediction of a Micro-Dosimeter Response Function  

NASA Technical Reports Server (NTRS)

A rapid analytical procedure for the prediction of a micro-dosimeter response function in low Earth orbit (LEO), correlated with the Space Transportation System (STS, shuttle) Tissue Equivalent Proportional Counter (TEPC) measurements is presented. The analytical model takes into consideration the energy loss straggling and chord length distribution of the detector, and is capable of predicting energy deposition fluctuations in a cylindrical micro-volume of arbitrary aspect ratio (height/diameter) by incoming ions through both direct and indirect (ray) events. At any designated (ray traced) target point within the vehicle, the model accepts the differential flux spectrum of Galactic Cosmic Rays (GCR) and/or trapped protons at LEO as input. On a desktop PC, the response function of TEPC for each ion in the GCR/trapped field is computed at the average rate of 30 seconds/ion. The ionizing radiation environment at LEO is represented by O'Neill fs GCR model (2004), covering charged particles in the 1 less than or equal to Z less than or equal to 28. O'Neill's free space GCR model is coupled with the Langley Research Center (LaRC) angular dependent geomagnetic cutoff model to compute the transmission coefficient in LEO. The trapped proton environment is represented by a LaRC developed time dependent procedure which couples the AP8MIN/AP8MAX, Deep River Neutron Monitor (DRNM) and F10.7 solar radio frequency measurements. The albedo neutron environment is represented by the extrapolation of the Atmospheric Ionizing Radiation (AIR) measurements. The charged particle transport calculations correlated with STS 51 and 114 flights are accomplished by using the most recent version (2005) of the LaRC deterministic High charge (Z) and Energy TRaNsport (HZETRN) code. We present the correlations between the TEPC model predictions (response function) and TEPC measured differential/integral spectra in the lineal energy (y) domain for both GCR and trapped protons, with the conclusion that the model correctly accounts for the increase in flux at low y values where energetic ions are the primary contributor. We further discuss that, even with the incorporation of angular dependency in the cutoffs, comparison of the GCR differential/integral flux between STS 51 and 114 TEPC measured data and current calculations indicates that there still exists an underestimation by the simulations at low to mid range y values. This underestimation is partly related the exclusion of the secondary pion particle production from the current version of HZETRN.

Badavi, Francis F.; Xapsos, Mike

2008-01-01

342

On the validity of the aluminum equivalent approximation in space radiation shielding applications  

NASA Astrophysics Data System (ADS)

The origin of the aluminum equivalent shield approximation in space radiation analysis can be traced back to its roots in the early years of the NASA space programs (Mercury, Gemini and Apollo) wherein the primary radiobiological concern was the intense sources of ionizing radiation causing short term effects which was thought to jeopardize the safety of the crew and hence the mission. Herein, it is shown that the aluminum equivalent shield approximation, although reasonably well suited for that time period and to the application for which it was developed, is of questionable usefulness to the radiobiological concerns of routine space operations of the 21st century which will include long stays onboard the International Space Station (ISS) and perhaps the moon. This is especially true for a risk based protection system, as appears imminent for deep space exploration where the long-term effects of Galactic Cosmic Ray (GCR) exposure is of primary concern. The present analysis demonstrates that sufficiently large errors in the interior particle environment of a spacecraft result from the use of the aluminum equivalent approximation, and such approximations should be avoided in future astronaut risk estimates. In this study, the aluminum equivalent approximation is evaluated as a means for estimating the particle environment within a spacecraft structure induced by the GCR radiation field. For comparison, the two extremes of the GCR environment, the 1977 solar minimum and the 2001 solar maximum, are considered. These environments are coupled to the Langley Research Center (LaRC) deterministic ionized particle transport code High charge ( Z) and Energy TRaNsport (HZETRN), which propagates the GCR spectra for elements with charges ( Z) in the range 1 ? Z ? 28 (H-Ni) and secondary neutrons through selected target materials. The coupling of the GCR extremes to HZETRN allows for the examination of the induced environment within the interior of an idealized spacecraft as approximated by a spherical shell shield, and the effects of the aluminum equivalent approximation for a good polymeric shield material such as generic polyethylene (PE). The shield thickness is represented by a 25 g/cm 2 spherical shell. Although, one could imagine the progression to greater thickness, the current range will be sufficient to evaluate the qualitative usefulness of the aluminum equivalent approximation. Upon establishing the inaccuracies of the aluminum equivalent approximation through numerical simulations of the GCR radiation field attenuation for PE and aluminum equivalent PE spherical shells, we further present results for a limited set of commercially available, hydrogen rich, multifunctional polymeric constituents to assess the effect of the aluminum equivalent approximation on their radiation attenuation response as compared to the generic PE.

Badavi, Francis F.; Adams, Daniel O.; Wilson, John W.

2010-09-01

343

Full Mission Astronaut Radiation Exposure Assessments for Long Duration Lunar Surface Missions  

NASA Technical Reports Server (NTRS)

Risk to astronauts due to ionizing radiation exposure is a primary concern for missions beyond Low Earth Orbit (LEO) and will drive mission architecture requirements, mission timelines, and operational practices. Both galactic cosmic ray (GCR) and solar particle event (SPE) environments pose a risk to astronauts for missions beyond LEO. The GCR environment, which is made up of protons and heavier ions covering a broad energy spectrum, is ever present but varies in intensity with the solar cycle, while SPEs are sporadic events, consisting primarily of protons moving outward through the solar system from the sun. The GCR environment is more penetrating and is more difficult to shield than SPE environments, but lacks the intensity to induce acute effects. Large SPEs are rare, but they could result in a lethal dose, if adequate shielding is not provided. For short missions, radiation risk is dominated by the possibility of a large SPE. Longer missions also require planning for large SPEs; adequate shielding must be provided and operational constraints must allow astronauts to move quickly to shielded locations. The dominant risk for longer missions, however, is GCR exposure, which accumulates over time and can lead to late effects such as cancer. SPE exposure, even low level SPE exposure received in heavily shielded locations, will increase this risk. In addition to GCR and SPE environments, the lunar neutron albedo resulting mainly from the interaction of GCRs with regolith will also contribute to astronaut risk. Full mission exposure assessments were performed for proposed long duration lunar surface mission scenarios. In order to accomplish these assessments, radiation shielding models were developed for a proposed lunar habitat and rover. End-to-End mission exposure assessments were performed by first calculating exposure rates for locations in the habitat, rover, and during extra-vehicular activities (EVA). Subsequently, total mission exposures were evaluated for proposed timelines. A number of computational tools and mathematical models, which have been incorporated into NASA's On-Line Tool for the Assessment of Radiation In Space (OLTARIS), were used for this study. These tools include GCR and SPE environment models, human body models, and the HZETRN space radiation transport code, which is used to calculate the transport of the charged particles and neutrons through shielding materials and human tissue. Mission exposure results, assessed in terms of effective dose, are presented for proposed timelines and recommendations are made for improved astronaut shielding and safer operational practice.

Adamczyk, Anne M.; Clowdsley, Martha S.; Qualls, Garry D.; Blattnig, Steve B.; Lee, Kerry T.; Fry, Dan J.; Stoffle, Nicholas N.; Simonsen, Lisa C.; Slaba, Tony C.; Walker, Steven A.; Zapp, Edward N.

2010-01-01

344

Radiation characteristics in the spherical tissue-equivalent phantom on the ISS during solar activity minimum according to the data from Liulin-5 experiment  

NASA Astrophysics Data System (ADS)

The Liulin-5 charged particle telescope observes the radiation characteristics in the spherical tissue-equivalent phantom of MATROSHKA-R international project on the International Space Station (ISS). Liulin-5 measures time resolved deposited energy spectra, linear energy transfer (LET) spectrum, flux and absorbed dose rates for electrons, protons and the biologically relevant heavy ion components of the cosmic radiation at three depths along the phantom's radius.We present some new results of Liulin-5 experiment obtained from June 2007 to March 2010.The average quality factor for different time intervals is between 2.7 and 4.4. Due to the heavy ions in LET spectrum of the galactic cosmic rays (GCR), the GCR quality factor is bigger than that of the trapped protons. The absorbed dose rates measured at depths in the phantom corresponding to the depths of blood forming organs in human body are 7.75-9.6?Gy/h and the dose equivalent rates are 24.6-36.7?Sv/h. Usually the trapped protons contribute about 60% of the total absorbed dose at 40mm depth in the phantom and about 40% at 165mm depth. The rest of the dose comes from GCR. Space Shuttle docking and the change of ISS attitude preformed for that purpose lead to a decrease in the total doses and to decreasing the trapped protons contributions. The doses from GCR are not affected neither by the depth of measurement not by Shuttle docking.At 165mm depth in the phantom the largest fluxes along the ISS orbit are obtained from the trapped protons in the South Atlantic Anomaly (SAA) at L values 1.26-1.27, B˜0.198Gs, geographical longitude ˜-51° to -55°, latitude ˜-28° to -29° and altitudes 361-363km. Minimal values about 0.1 particles/cm2s were recorded at L˜1 from GCR, at L?4 the GCR flux reaches 2.1 particles/cm2s.

Semkova, J.; Koleva, R.; Maltchev, St.; Bankov, N.; Benghin, V.; Chernykh, I.; Shurshakov, V.; Petrov, V.

2013-07-01

345

Integration of the QMSFRG Database into the HZETRN Code  

NASA Technical Reports Server (NTRS)

Accurate nuclear interaction data bases are needed for describing the transport of space radiation in matter including space craft structures, atmospheres, and tissues. Transport models support the identification and development of new material concepts for human and electronic part protection. Quantum effects are manifested in nuclear reactions in several ways including interference effects between terms in the multiple scattering series, the many-body nuclear wave functions (for e.g. the roles of shell structure and Fermi momentum) and nuclear clustering. The quantum multiple scattering fragmentation model (QMSFRG) is a comprehensive model for generating nuclear interaction databases for galactic cosmic ray (GCR) transport. Other nuclear databases including the NUCFRG model and Monte-Carlo simulation codes such as FLUKA, LAHET, HETC, and GEANT ignore quantum effects. These codes fail to describe many important features of nuclear reactions and are thus inaccurate for the evaluation of materials for radiation protection. Previously we have shown that quantum effects are manifested through constructive interference in forward production spectra, the effects of Fermi momentum on production spectra, cluster nuclei knockout, and the nuclear response function. Quantum effects are especially important for heavy ions with mass numbers less than 20 that dominate radiation transport in human tissues and for the materials that are expected to be superior in space radiation protection. We describe the integration of the QMSFRG model into the HZETRN transport code. Integration milestones include proper treatment of odd-even charge-mass effects in nuclear fragmentation and the momentum distribution of nucleon production from GCR primary heavy ions. We have also modified the two-body amplitudes in the model to include nuclear medium effects. In order to include a comprehensive description of the GCR isotopic composition in materials, we have described the isotopic composition of the GCR by extending the 59-isotope version of HZETRN to an 120-isotope version. The isotopic composition of most primary GCR elements (including H, He, C, N, O, Ne, Mg, Si, Ar, Ca, Cr, and Fe) are included in the extended model. We discuss results for the high-energy neutron composition inside materials, and the charge and mass distribution for benchmark GCR problems.

Cucinotta, F. A.; Shavers, M. R.; Tripathi, R. K.; Wilson, J. W.

2001-01-01

346

Solar Particle Events Observed by the Odyssey MARIE Instrument at Mars: Dose and Model Calculations  

NASA Technical Reports Server (NTRS)

One of the primary concerns prior to human exploration of Mars is the need to accurately characterize the charged particle radiation environment both for the surface stay, and for the transit period to and from the planet. The Odyssey spacecraft, currently in Mars orbit includes a charged particle radiation detector, MARIE, which can measure particle fluxes with energies above approx. 30 MeV and charges between 1 and 10. Two classes of particles are of particular interest: the Galactic Cosmic Rays, (GCR), and those charged particles associated with Solar Particle Events, (SPE). The GCR are present continuously throughout the solar activity cycle, and their numbers vary inversely with the level of solar activity. They are characteristically more energetic than those particles originating from solar activity, and hence less influences by the solar magnetic field.

Cleghorn, T. F.; Saganti, P. B.; Zeitlin, C. J.; Cucinotta, F. A.

2003-01-01

347

[A study of cognitive and behavioral development in pre-school and school children with high functioning pervasive developmental disorder].  

PubMed

It has been reported that school-aged children with high functioning pervasive developmental disorder (HFPDD) have numerous difficulties in their school class. We used three psychological tests to investigate whether there is a relationship between intelligence and cognitive, behavioral development in children with HFPDD. The three tests used were an intelligence test (WIPPSI, WISC-lll), the P-F (Picture Frustration) study, and behavioral assessment by their parents. In the P-F study, 60% of 23 children with HFPDD showed a GCR% (Group Conformity Rating) above or below the standard. There was no relationship between GCR% and IQ. In the behavioral assessment by their parents, over 50% of 40 children with HFPDD showed maladaptive behaviors. The high VIQ group showed more maladaptive behaviors than the low VIQ group. These findings suggest that school-aged children with H-FPDD need educational treatment for social deficits and maladaptive behaviors. PMID:19928539

Tsuda, Yoshimi; Hashimoto, Toshiaki; Mori, Kenji; Nishimura, Mio; Fukumoto, Aya; Fujii, Emiko; Takahara, Mitsue

2009-11-01

348

Optimized Shielding for Space Radiation Protection  

NASA Technical Reports Server (NTRS)

Abstract. Future deep space mission and International Space Station exposures will be dominated by the high-charge and -energy (HZE) ions of the Galactic Cosmic Rays (GCR). A few mammalian systems have been extensively tested over a broad range of ion types and energies. For example, C3H10T1/2 cells, V79 cells, and Harderian gland tumors have been described by various track-structure dependent response models. The attenuation of GCR induced biological effects depends strongly on the biological endpoint, response model used, and material composition. Optimization of space shielding is then driven by the nature of the response model and the transmission characteristics of the given material.

Wilson, J. W.; Cucinotta, F. A.; Kim, M.-H. Y.; Schimmerling, W.

2000-01-01

349

Galactic cosmic ray decreases associated with non-interacting magnetic clouds in the 23 rd solar cycle  

NASA Astrophysics Data System (ADS)

Sudden Galactic Cosmic Ray (GCR) intensity decreases are related to the passage of Interplanetary Coronal Mass Ejections (ICMEs). These phenomena are also known as Forbush Decreases (FDs). The deepest FDs are associated with the passage of Magnetic Clouds (MCs). In this preliminary study we select ``non-interacting'' MCs associated with FDs observed from ground Neutron Monitors in the period 1996-2009, with the aim of reducing the complexity and the number of parameters involved in the GCR-MC interactions. We introduce a method to determine properties of the ``ejecta component'' of the FD. We analyze properties of the ejecta component in combination with properties of MCs. From the resulting selection of events, we find that those FDs containing ejecta components show stronger correlations with MC parameters than our total sample of events.

Masías-Meza, J. J.; Dasso, S.

2014-01-01

350

Cosmic-ray record in solar system matter  

NASA Technical Reports Server (NTRS)

The interaction of galactic cosmic rays (GCR) and solar cosmic rays (SCR) with bodies in the solar system is discussed, and what the record of that interaction reveals about the history of the solar system is considered. The influence of the energy, charge, and mass of the particles on the interaction is addressed, showing long-term average fluxes of solar protons, predicted production rates for heavy-nuclei tracks and various radionuclides as a function of depth in lunar rock, and integral fluxes of protons emitted by solar flares. The variation of the earth's magnetic field, the gardening of the lunar surface, and the source of meteorites and cosmic dust are studied using the cosmic ray record. The time variation of GCR, SCR, and VH and VVH nuclei is discussed for both the short and the long term.

Reedy, R. C.; Arnold, J. R.; Lal, D.

1983-01-01

351

Solar cosmic ray produced neon in lunar soils and their implication for gas-rich meteorite studies  

NASA Technical Reports Server (NTRS)

Characteristic neon isotopic ratios, produced due to solar cosmic ray spallation (SCR) in lunar soils, are useful in deciphering and estimating the relative contributions of SCR and GCR spallation. To delineate these features, etched mineral grains from mature and immature lunar soils (14148 and 61221 respectively) were analyzed using mass spectrometry. The SF-Ne composition deduced in this work agrees with that obtained from earlier etched lunar pyroxene studies. The data points for mature soil 14148 define a line which significantly deviates from the 61221 tie line. This deviation is attributed to the presence of SCR spallation component. In this context, neon isotopic compositions (step-wise heating) in Pantar and Leighton dark portions were studied and compared with that of Fayetteville. The meteorite data points deviate significantly from the tie line joining SF-Ne and GCR (pyroxene) end points. This deviation is attributed to SCR-spallation in gas-rich chondrites.

Nautiyal, C. M.; Rao, M. N.

1984-01-01

352

Galactic cosmic ray abundances and spectra behind defined shielding.  

PubMed

LET spectra have been measured for lunar missions and for several near Earth orbits ranging from 28 degrees to 83 degrees inclination. In some of the experiments the flux of GCR was determined separately from contributions caused by interactions in the detector material. Results of these experiments are compared to model calculations. The general agreement justifies the use of the model to calculate GCR fluxes. The magnitude of variations caused by solar modulation, geomagnetic shielding, and shielding by matter determined from calculated LET spectra is generally in agreement with experimental data. However, more detailed investigations show that there are some weak points in modeling solar modulation and shielding by material. These points are discussed in more detail. PMID:11540030

Heinrich, W; Benton, E V; Wiegel, B; Zens, R; Rusch, G

1994-10-01

353

Predicting space climate change  

NASA Astrophysics Data System (ADS)

The recent decline in the open magnetic flux of the Sun heralds the end of the Grand Solar Maximum (GSM) that has persisted throughout the space age, during which the largest-fluence Solar Energetic Particle (SEP) events have been rare and Galactic Cosmic Ray (GCR) fluxes have been relatively low. In the absence of a predictive model of the solar dynamo, we here make analogue forecasts by studying past variations of solar activity in order to evaluate how long-term change in space climate may influence the hazardous energetic particle environment of the Earth in the future. We predict the probable future variations in GCR flux, near-Earth interplanetary magnetic field (IMF), sunspot number, and the probability of large SEP events, all deduced from cosmogenic isotope abundance changes following 24 GSMs in a 9300-year record.

Barnard, L.; Lockwood, M.; Hapgood, M. A.; Owens, M. J.; Davis, C. J.; Steinhilber, F.

2011-08-01

354

Cermet coating tribological behavior in high temperature helium  

SciTech Connect

As the CEA is highly involved in the Generation IV Forum, a comprehensive research and development program has been conducted for several years, in order to establish the feasibility of Gas Cooled Reactor (GCR) technology projects using helium as a cooling fluid. Within this framework, a tribology program was launched in order to select and qualify coatings and materials, and to provide recommendations for the sliding components operating in GCRs. The purpose of this paper is to describe the CEA Helium tribology study on several GCR components (thermal barriers, control rod drive mechanisms, reactor internals, ..) requiring protection against wear and bonding. Tests in helium atmosphere are necessary to be fully representative of tribological environments and to assess the material or coating candidates which can provide a reliable answer to these situations. This paper focuses on the tribology tests performed on CERMET (Cr{sub 3}C-2- NiCr) coatings within a temperature range of between 800 and 1000 deg C.

CACHON, Lionel; ALBALADEJO, Serge; TARAUD, Pascal; LAFFONT, G. [Centre de Cadarache, 13108 Saint-Paul-lez-Durance (France)

2006-07-01

355

Evidence for Recent Gardening or Disturbance in Lunar Core 76001 from Solar-Cosmic-Ray Records of 14C  

NASA Astrophysics Data System (ADS)

Due to their long exposure times, lunar soils and rocks provide a continuous record of galactic (GCR) and solar-cosmic-ray (SCR) intensities. Lunar cores are very useful in studies of the production of nuclides by GCR particles in very large objects. Lunar samples also contain especially good records of SCR effects and variations of SCR fluxes in the past. We report on new 14C measurements obtained as a function of depth in the Apollo 17 drive tube core, 76001. This core was described as undisturbed by NASA documentation. The core was collected at a break in the slope of North Massif, on an 11o slope. Results are shown in the figure and compared to our earlier experimental results on the apparently undisturbed Apollo 15 cores 15001-15006 and 15008. The results show a disturbance of the core data in the top few g/cm^2 of this core.

Jull, A. J. T.; Cloudt, S.

1996-03-01

356

Solution-phase growth of organic single-crystal arrays  

NASA Astrophysics Data System (ADS)

We have successfully developed a method for directly forming organic single-crystal thin films at designated locations on a substrate by solution-phase growth. An original micropattern, in which small rectangular regions were connected to a large rectangular region, was designed. The small regions and the large region were used as nucleation control regions (NCRs) and a growth control region (GCR), respectively. The key to success was to vary local supersaturation of a solution droplet by making a large difference in solvent evaporation between a NCR and a GCR. We found that the NCR played a very important role in forming a single nucleus and in investigating the possibility of control of the crystal orientation. By using the developed micropattern and controlling the solvent vapor pressure during growth, we fabricated single-crystal arrays of a stable organic semiconductor, 3,9-bis(4-ethylphenyl)-peri-xanthenoxanthene (C2Ph-PXX).

Goto, Osamu; Tomiya, Shigetaka; Murakami, Yosuke; Shinozaki, Akira; Toda, Akira; Kasahara, Jiro; Hobara, Daisuke

2012-10-01

357

The descent of the solar cycle 24 cosmic ray modulation  

NASA Astrophysics Data System (ADS)

The descending phase of the galactic cosmic ray (GCR) modulation at earth orbit, for the sunspot number (SSN) cycle 24 is studied, using data from the global network of neutron monitors and the balloon measurements at high latitudes in Russia. The decrease in intensity, two years after the onset of modulation, is modest compared to earlier cycles. The tilt angle of the heliospheric current sheet is very close to its maximum value for a cycle and the solar polar field has reversed in the northern hemisphere. So, one should expect the GCR modulation to be close to its maximum value. A preliminary determination is made of the rigidity dependence of the observed modulation for two years. It is a power law with an exponent -1.11, similar to that observed for earlier cycles (20-23).

Ahluwalia, H. S.; Ygbuhay, R. C.

2013-06-01

358

Radiation quality of cosmic ray nuclei studied with Geant4-based simulations  

NASA Astrophysics Data System (ADS)

In future missions in deep space a space craft will be exposed to a non-negligible flux of high charge and energy (HZE) particles present in the galactic cosmic rays (GCR). One of the major concerns of manned missions is the impact on humans of complex radiation fields which result from the interactions of HZE particles with the spacecraft materials. The radiation quality of several ions representing GCR is investigated by calculating microdosimetry spectra. A Geant4-based Monte Carlo model for Heavy Ion Therapy (MCHIT) is used to simulate microdosimetry data for HZE particles in extended media where fragmentation reactions play a certain role. Our model is able to reproduce measured microdosimetry spectra for H, He, Li, C and Si in the energy range of 150-490 MeV/u. The effect of nuclear fragmentation on the relative biological effectiveness (RBE) of He, Li and C is estimated and found to be below 10%.

Burigo, Lucas N.; Pshenichnov, Igor A.; Mishustin, Igor N.; Bleicher, Marcus

2014-04-01

359

Isotopes in galactic cosmic rays  

NASA Astrophysics Data System (ADS)

Four possible scenarios for the origin of the isotopic ratio of neon in galactic cosmic rays (GCR), (which differs from the solar system ratio), are discussed. The observed compositional effects may actually represent biases in the acceleration. Selective acceleration effects for neon exist either in the solar wind or in solar flares, and extreme variations for helium are seen in solar flares. The abundance of Ne-22 could be explained as due to small star nucleosynthesis, but the absence of N increase between the birth of the sun and now argues against this. The idea that supernovae are contributing fresh material to the GCR has little evidential support. More plausible is the notion that CGR, including the excess Ne-22, could be an outflow from OB star assemblages, including WR stars. The latter have lost their atmospheres through Roche lobe overflow, exposing the surface rich in nucleosynthetic products. These are blown away by the powerful stellar wind.

Reeves, H.

360

Study - Radiation Shielding Effectiveness of the Prototyped High Temperature Superconductivity (HTS) 'Artificial' Magnetosphere for Deep Space Missions  

NASA Technical Reports Server (NTRS)

The high temperature superconductor (HTS) is being used to develop the magnets for the Variable Specific Impulse Magneto-plasma Rocket (VASIMR ) propulsion system and may provide lightweight magnetic radiation shielding to protect spacecraft crews from radiation caused by GCR and SPEs on missions to Mars. A study is being planned to assess the radiation shielding effectiveness of the artificial magnetosphere produced by the HTS magnet. VASIMR is an advanced technology propulsion engine which is being touted as enabling one way transit to Mars in 90 days or less. This is extremely important to NASA. This technology would enable a significant reduction in the number of days in transit to and from Mars and significantly reduce the astronauts exposure to a major threat - high energy particles from solar storms and GCR during long term deep space missions. This paper summarizes the plans for the study and the subsequent testing of the VASIMR technology onboard the ISS slated for 2013.

Denkins, Pamela

2010-01-01

361

Light ion components of the galactic cosmic rays: Nuclear interactions and transport theory  

NASA Technical Reports Server (NTRS)

Light nuclei are present in the primary galactic cosmic rays (GCR) and are produced in thick targets due to projectile or target fragmentation from both nucleon and heavy induced reactions. In the primary GCR, He-4 is the most abundant nucleus after H-1. However, there are also a substantial fluxes of H-2 and He-3. In this paper we describe theoretical models based on quantum multiple scattering theory for the description of light ion nuclear interactions. The energy dependence of the light ion fragmentation cross section is considered with comparisons of inclusive yields and secondary momentum distributions to experiments described. We also analyze the importance of a fast component of lights ions from proton and neutron induced target fragementation. These theoretical models have been incorporated into the cosmic ray transport code HZETRN and will be used to analyze the role of shielding materials in modulating the production and the energy spectrum of light ions.

Cucinotta, F. A.; Townsend, L. W.; Wilson, J. W.; Shinn, J. L.; Badhwar, G. D.; Dubey, R. R.

1996-01-01

362

Numerical Study of the Generation of Linear Energy Transfer Spectra for Space Radiation Applications  

NASA Technical Reports Server (NTRS)

In analyzing charged particle spectra in space due to galactic cosmic rays (GCR) and solar particle events (SPE), the conversion of particle energy spectra into linear energy transfer (LET) distributions is a convenient guide in assessing biologically significant components of these spectra. The mapping of LET to energy is triple valued and can be defined only on open energy subintervals where the derivative of LET with respect to energy is not zero. Presented here is a well-defined numerical procedure which allows for the generation of LET spectra on the open energy subintervals that are integrable in spite of their singular nature. The efficiency and accuracy of the numerical procedures is demonstrated by providing examples of computed differential and integral LET spectra and their equilibrium components for historically large SPEs and 1977 solar minimum GCR environments. Due to the biological significance of tissue, all simulations are done with tissue as the target material.

Badavi, Francis F.; Wilson, John W.; Hunter, Abigail

2005-01-01

363

Quiet-Time Spectra and Abundances of Energetic Particles During the 1996 Solar Minimum  

NASA Technical Reports Server (NTRS)

This report concerns the energy spectra and abundances of ions with atomic number, Z, in the interval 2 greater than or equal to Z and Z less than or equal to 36 and energies approximately 3-20 MeV/amu for solar and interplanetary quiet periods between November 1994 and April 1998 as measured by the large-geometry LEMT telescope on the Wind spacecraft near Earth. The energy spectra show the presence of galactic (GCR) and 'anomalous' cosmic ray (ACR) components, depending on the element. ACR components are reported for Mg and Si for the first time at 1 AU and the previous observation of S and Ar is confirmed. However, only GCR components are clearly apparent for the elements Ca, Ti, Cr, Fe, as well as for C. New limits are placed on a possible ACR contribution for other elements, including Kr.

Reames, Donald V.

1998-01-01

364

Quiet-Time Spectra and Abundances of Energetic Particles During the 1996 Solar Minimum  

NASA Technical Reports Server (NTRS)

We report the energy spectra and abundances of ions with atomic number, Z, in the interval Z is greater than or equal to 2 and Z is less than or equal to 36 and energies approximately 3-20 MeV/amu for solar and interplanetary quiet periods between 1994 November and 1998 April as measured by the large-geometry Low Energy Matrix Telescope (LEMT) telescope on the Wind spacecraft near Earth. The energy spectra show the presence of galactic (GCR) and "anomalous" cosmic ray (ACR) components, depending on the element. ACR components are reported for Mg and Si for the first time at 1 AU and the previous observation of S and Ar is confirmed. However, only GCR components are clearly apparent for the elements Ca, Ti, Cr, Fe, as well as for C. New limits are placed on a possible ACR contribution for other elements, including Kr.

Reames, Donald V.

1999-01-01

365

The Heavy Nuclei eXplorer (HNX) Mission  

NASA Technical Reports Server (NTRS)

The primary scientific objectives of HNX, which was recently selected by NASA for a Small Explorer (SMEX) Mission Concept Study, are to measure the age of the galactic cosmic rays (GCR) since nucleosynthesis, determine the injection mechanism for the GCR accelerator (Volatility or FIP), and study the mix of nucleosynthetic processes that contribute to the source of GCRs. The experimental goal of HNX is to measure the elemental abundances of all individual stable nuclei from neon through the actinides and possibly beyond. HNX is composed of two instruments: ECCO, which measures elemental abundances of nuclei with Z greater than or equal to 72, and ENTICE. which measures elemental abundances of nuclei with Z between 10 and 82. We describe the mission and the science that can be addressed by HNX.

Binns, W. R.; Adams, J. H.; Barbier, L. M.; Craig, N.; Cummings, A. C.; Cummings, J. R.; Doke, T.; Hasebe, N.; Hayashi, T.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

366

Effects of radiobiological uncertainty on vehicle and habitat shield design for missions to the moon and Mars  

SciTech Connect

Some consequences of uncertainties in radiobiological risk due to galactic cosmic ray (GCR) exposure are analyzed for their effect on engineering designs for the first lunar outpost and a mission to explore Mars. This report presents the plausible effect of biological uncertainties, the design changes necessary to reduce the uncertainties to acceptable levels for a safe mission, and an evaluation of the mission redesign cost. Estimates of the amount of shield mass required to compensate for radiobiological uncertainty are given for a simplified vehicle and habitat. The additional amount of shield mass required to provide a safety factor for uncertainty compensation is calculated from the expected response to GCR exposure. The amount of shield mass greatly increases in the estimated range of biological uncertainty, thus, escalating the estimated cost of the mission. The estimates are used as a quantitative example for the cost-effectiveness of research in radiation biophysics and radiation physics.

Wilson, J.W.; Nealy, J.E.; Schimmerling, W.; Cucinotta, F.A.; Wood, J.S.

1993-08-01

367

Cosmic Ray Modulation in the Outer Heliosphere During the Minimum of Solar Cycle 23/24  

NASA Technical Reports Server (NTRS)

We report a next generation model of galactic cosmic ray (GCR) transport in the three dimensional heliosphere. Our model is based on an accurate three-dimensional representation of the heliospheric interface. This representation is obtained by taking into account the interaction between partially ionized, magnetized plasma flows of the solar wind and the local interstellar medium. Our model reveals that after entering the heliosphere GCRs are stored in the heliosheath for several years. The preferred GCR entry locations are near the nose of the heliopause and at high latitudes. Low-energy (hundreds of MeV) galactic ions observed in the heliosheath have spent, on average, a longer time in the solar wind than those observed in the inner heliosphere, which would explain their cooled-off spectra at these energies. We also discuss radial gradients in the heliosheath and the implications for future Voyager observations.

Adams, James H., Jr.; Florinski, V.; Washimi, H.; Pogorelov, N. V.

2011-01-01

368

3-D models of the Forbush decrease and 27-day variation of galactic cosmic rays with three dimensional divergence-free interplanetary magnetic field  

NASA Astrophysics Data System (ADS)

We develop the three dimensional (3-D) models of the Forbush decrease (Fd) and 27-day variation of the galactic cosmic ray (GCR) intensity with the variable solar wind velocity. In the models is implemented a structure of the three dimensional interplanetary magnetic field (IMF) obtained as a numerical solution of Maxwell's equations with the heliolongitudinal and heliolatitudinal dependencies of the radial component of the solar wind velocity that approximately corresponds to in situ measurements. Based on the Bernoulli principle we consider the possible circumstances leading to the formation of the latitudinal B _{?} component of the IMF due to violence of the equilibrium between different layers of the variable solar wind streams. We compare 3-D modeling results of the Forbush decrease (Fd) and 27-day variation of the GCR intensity with the observed variation of cosmic ray intensity from world wide network of neutron monitors.

Alania, Michael; Modzelewska, Renata; Wawrzynczak-Szaban, Anna

2012-07-01

369

Preliminary Design of a Galactic Cosmic Ray Shielding Materials Testbed for the International Space Station  

NASA Technical Reports Server (NTRS)

The preliminary design of a testbed to evaluate the effectiveness of galactic cosmic ray (GCR) shielding materials, the MISSE Radiation Shielding Testbed (MRSMAT) is presented. The intent is to mount the testbed on the Materials International Space Station Experiment-X (MISSE-X) which is to be mounted on the International Space Station (ISS) in 2016. A key feature is the ability to simultaneously test nine samples, including standards, which are 5.25 cm thick. This thickness will enable most samples to have an areal density greater than 5 g/sq cm. It features a novel and compact GCR telescope which will be able to distinguish which cosmic rays have penetrated which shielding material, and will be able to evaluate the dose transmitted through the shield. The testbed could play a pivotal role in the development and qualification of new cosmic ray shielding technologies.

Gaier, James R.; Berkebile, Stephen; Sechkar, Edward A.; Panko, Scott R.

2012-01-01

370

The Status of Radiation Estimates for Human Missions to the Moon and Mars  

NASA Astrophysics Data System (ADS)

Astronaut exposure to ionizing radiation will be a primary concern for missions to the moon and Mars and may become a limiting factor for long duration missions Methodologies for evaluating this risk in terms of radiation protection quantities are described Environment models vehicle habitat shielding models and transport codes are discussed Here the environmental models include solar particle event SPE and time dependant galactic cosmic ray GCR models for free space as well as lunar and Martian surface SPE and GCR models which are altitude and surface material dependant Exposures are calculated for sample missions Since radiation limits for missions beyond low Earth orbit LEO have not yet been defined these exposures are compared to current LEO limits Possible exploration mission limits are also discussed

Clowdsley, M.; Wilson, J.; Deangelis, G.

371

Modulation of Galactic Cosmic Rays during the Last Solar Cycle: Modeling with Continuously Changing Heliospheric Current Sheet  

NASA Astrophysics Data System (ADS)

The last long lasting Solar Minimum was unique in more ways than one. The heliospheric magnetic field (HMF) decreased to be the weakest ever recorded, while the heliospheric current sheet (HCS) dividing the two magnetic polarities remained moderately tilted quite until 2009. In 2009, the HCS flattened and GCR fluxes reached record level. We present a simple numerical model where we change the magnetic field strength and HCS tilt at the Sun, and passively propagate these changes into the heliosphere by the solar wind, generating corresponding temporal changes in the HMF, in the diffusion coefficients, and in the tilted HCS. We find that the increase of GCR intensity in 2009 may be associated with the flattening of the HCS. If so, our results suggest that particle drifts played dominant role in the transport of GCRs during this period.

Kota, J.

2010-12-01

372

Krylov Subspace and Multigrid Methods Applied to the Incompressible Navier-Stokes Equations  

NASA Technical Reports Server (NTRS)

We consider numerical solution methods for the incompressible Navier-Stokes equations discretized by a finite volume method on staggered grids in general coordinates. We use Krylov subspace and multigrid methods as well as their combinations. Numerical experiments are carried out on a scalar and a vector computer. Robustness and efficiency of these methods are studied. It appears that good methods result from suitable combinations of GCR and multigrid methods.

Vuik, C.; Wesseling, P.; Zeng, S.

1996-01-01

373

Radiation Measured with Different Dosimeters for ISS-Expedition 18-19/ULF2 on Board International Space Station during Solar Minimum  

NASA Astrophysics Data System (ADS)

Radiation field of particles in low Earth orbit (LEO) is mainly composed of galactic cosmic rays (GCR), solar energetic particles and particles in SAA (South Atlantic Anomaly). GCR are modulated by solar activity, at the period of solar minimum activity, GCR intensity is at maximum and the main contributor for space radiation is GCR. At present for space radiation measurements conducted by JSC (Johnson Space Center) -SRAG (Space Radiation Analysis Group), the preferred active dosimeter sensitive to all LET (Linear Energy Transfer) is the tissue equivalent proportional counter (TEPC); the preferred passive dosimeters are thermoluminescence dosimeters (TLDs) and optically stimulated luminescence dosimeters (OSLDs) sensitive to low LET as well as CR-39 plastic nuclear track detectors (PNTDs) sensitive to high LET. For the method using passive dosimeters, radiation quantities for all LET can be obtained by combining radiation results measured with TLDs/OSLDs and CR-39 PNTDs. TEPC, TLDs/OSLDs and CR-39 detectors were used to measure the radiation field for the ISS (International Space Station) -Expedition 18-19/ULF2 space mission which was conducted from 15 November 2008 to 31 July 2009 -near the period of the recent solar minimum activity. LET spectra (differential and integral fluence, absorbed dose and dose equivalent) and radiation quantities were measured for positions TEPC, TESS (Temporary Sleeping Station, inside the polyethylene lined sleep station), SM-P 327 and 442 (Service Module -Panel 327 and 442). This paper presents radiation LET spectra measured with TEPC and CR-39 PNTDs and radiation dose measured with TLDs/OSLDs as well as the radiation quantities combined from results measured with passive dosimeters.

Zhou, Dazhuang

374

Radiological health risks for exploratory class missions in space.  

PubMed

Crewmembers on missions to the Moon or Mars will be unavoidably exposed to ionizing radiation as they pass through the Van Allen belts and the Galactic Cosmic Ray (GCR) flux. There is the possibility for exposure to proton radiation from Solar Particle Events (SPE). Using absorbed doses and ICRP 26, Linear Energy Transfer (LET) -dependent quality factors, the following dose-equivalents are estimated: In a spacecraft with 0.75 cm aluminum walls (2 g/cm2) at solar minimum, the lunar round trip dose-equivalent is less than 0.05 Sv. During a Mars mission the estimated dose-equivalents are: outbound (Van Allen Belts) <0.02 Sv; Earth to Mars (205 days exposure to free space GCR) 0.32 Sv; 30 days on the Martian surface (GCR) 0.023 Sv; Mars to Earth (225 days exposure to free space) 0.35 Sv; and through the Van Allen Belts 0.02 Sv. Conventionally, the total of 0.73 Sv over 460 days could be expected to increase the risk of cancer mortality in a 35-year old male astronaut by about one percent. However three-fourths of the dose-equivalent in free space is contributed by high LET heavy ions (Z > or = 3) and target fragments with average quality factors of 10.3 and 20 respectively. The biological effectiveness of these radiations is poorly understood; so the quality factors are set at conservatively very high values. The entire concept of absorbed dose/quality factor/dose-equivalent as applied to GCR must be reconsidered. PMID:11537128

Nachtwey, D S; Yang, T C

1991-01-01

375

Minimizing Astronauts' Risk from Space Radiation during Future Lunar Missions  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the risk factors from space radiation for astronauts on future lunar missions. Two types of radiation are discussed, Galactic Cosmic Radiation (GCR) and Solar Particle events (SPE). Distributions of Dose from 1972 SPE at 4 DLOCs inside Spacecraft are shown. A chart with the organ dose quantities is also given. Designs of the exploration class spacecraft and the planned lunar rover are shown to exhibit radiation protections features of those vehicles.

Kim, Myung-Hee Y.; Hayat, Mathew; Nounu, Hatem N.; Feiveson, Alan H.; Cucinotta, Francis A.

2007-01-01

376

Laser transformation hardening of precision V-slide way  

Microsoft Academic Search

The results of the study of the application of laser transformation hardening (LTH) on the precision slide ways and some specimens of 20, 45, GCr15, 18Cr2Ni4WA, or other steels by a 1KW transverse CO2 laser are presented. It is concluded that the LTH can meet all the requirements, such as the case hardness, case depth, distortion allowance, wear resistance, and

G. Zhang; Q. Yang; Y. Wu

1986-01-01

377

Cosmic Rays During the Most-Recent Sunspot Minimum  

NASA Astrophysics Data System (ADS)

During the sunspot minimum between solar cycles 23 and 24, galactic cosmic rays (GCR) reached the highest intensity seen during the spacecraft era. This was due in part to the lower open solar magnetic flux and slower solar wind seen during this period, compared to previous solar minima. The effects of cosmic-ray drifts along the heliospheric current sheet (HCS) has yet to be completely understood; but it is interesting to note that while the HCS was generally not as flat as one might expect given the very quiet Sun, it was at its flattest when the GCR intensity was at its highest. This is important because during this solar magnetic cycle, cosmic-ray protons drift into the heliosphere along the HCS. And, despite the unusually high GCR intensity during this solar minimum, the intensity of anomalous cosmic rays (ACR) was NOT seen to be as high as in previous sunspot minima. Moreover, the GCR electron intensity at the two Voyager spacecraft, which are both approaching the heliopause, is seen to be quite different. These observations lead to important questions regarding the transport of cosmic rays in the heliospheric magnetic field, which originates at the Sun. Particularly important is the transport of cosmic rays across the magnetic field, the role of the heliosheath in cosmic-ray modulation, drifts at the HCS, and the differences between ACRs and GCRs. In this talk, we will review our understanding of cosmic-ray transport in the solar and heliospheric magnetic field and discuss how observations will help resolve these recent puzzles and give constraints on transport parameters.

Giacalone, Joe; Jokipii, Jack; Kota, Jozsef

2012-07-01

378

Cosmic Rays During the Most-Recent Sunspot Minimum  

NASA Astrophysics Data System (ADS)

During the sunspot minimum between solar cycles 23 and 24, galactic cosmic rays (GCR) reached the highest intensity seen during the spacecraft era. This was due in part to the lower open solar magnetic flux and slower solar wind seen during this period, compared to previous solar minima. The effects of cosmic-ray drifts along the heliospheric current sheet (HCS) has yet to be completely understood; but it is interesting to note that while the HCS was generally not as flat as one might expect given the very quiet Sun, it was at its flattest when the GCR intensity was at its highest. This is important because during this solar magnetic cycle, cosmic-ray protons drift into the heliosphere along the HCS. And, despite the unusually high GCR intensity during this solar minimum, the intensity of anomalous cosmic rays (ACR) was NOT seen to be as high as in previous sunspot minima. Moreover, the GCR electron intensity at the two Voyager spacecraft, which are both approaching the heliopause, is seen to be quite different. These observations lead to important questions regarding the transport of cosmic rays in the heliospheric magnetic field, which originates at the Sun. Particularly important is the transport of cosmic rays across the magnetic field, the role of the heliosheath in cosmic-ray modulation, drifts at the HCS, and the differences between ACRs and GCRs. In this talk, we will review our understanding of cosmic-ray transport in the solar and heliospheric magnetic field and discuss how observations will help resolve these recent puzzles and give constraints on transport parameters.

Giacalone, J.; Jokipii, J. R.; Kota, J.

2011-12-01

379

An Algorithm for the Transport of Anisotropic Neutrons  

NASA Technical Reports Server (NTRS)

One major obstacle to human space exploration is the possible limitations imposed by the adverse effect of long-term exposure to the space environment. Even before human spaceflight began, the potentially brief exposure of astronauts to the very intense random solar particle events (SPE) were of great concern. A new challenge appears in deep space exploration from exposure to the low-intensity heavy-ion flux of the galactic cosmic rays (GCR) since the missions are of long duration and the accumulated GCR exposures can be high. Because cancer induction rates increase behind low to rather large thicknesses of aluminum shielding, according to available biological data on mammalian exposures to GCR like ions, the shield requirements for a Mars mission are prohibitively expensive in terms of mission launch costs. Therefore, a critical issue in the Human Exploration and Development of Space enterprise is cost effective mitigation of risk associated with ionizing radiation exposure. In order to estimate astronaut risk to GCR exposure and associated cancer risks and health hazards, it is necessary to do shield material studies. To determine an optimum radiation shield material it is necessary to understand nuclear interaction processes such as fragmentation and secondary particle production which is a function of energy dependent cross sections. This requires knowledge of material transmission characteristics either through laboratory testing or improved theoretical modeling. Here ion beam transport theory is of importance in that testing of materials in the laboratory environment generated by particle accelerators is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are a major emphasis of the present work.

Tweed, J.

2005-01-01

380

The Feasibility of Multipole Electrostatic Radiation Shielding  

NASA Technical Reports Server (NTRS)

Although passive shielding appears to be the only workable solution for galactic cosmic radiation (GCR), active shielding may play an important augmenting role to control the dose from solar particle events (SPEs). It has been noted that, to meet the guidelines of NCRP Report No. 98 through the six SPEs of 1989, a crew member would need roughly double the passive shielding that is necessary to control the GCR dose . This would dramatically increase spacecraft mass, and so it has been proposed that a small but more heavily shielded storm shelter may be used to protect the crew during SPEs. Since a gradual SPE may last 5 or more days, staying in a storm shelter may be psychologically and physiologically distressing to the crew. Storm shelters do not provide shielding for the spacecraft itself against the SPE radiation, and radiation damage to critical electronics may result in loss of mission and life. Single-event effects during the radiation storm may require quick crew response to maintain the integrity of the spacecraft, and confining the crew to a storm shelter prohibits their attending to the spacecraft at the precise time when that attention is needed the most. Active shielding cannot protect against GCR because the particle energies are too high. Although lower energy particles are easier to stop in a passive shield, such shielding is more satisfactory against GCR than against SPE radiation because of the tremendous difference in their initial fluences. Even a small fraction of the SPE fluence penetrating the passive shielding may result in an unacceptably high dose. Active shielding is more effective than passive shielding against SPE radiation because it offers 100% shielding effectiveness up to the cutoff energy, and significant shielding effectiveness beyond the cutoff as well.

Metzger, Philip T.; Lane, John E.; Youngquist, Robert C.

2004-01-01

381

Application of real-time radiation dosimetry using a new silicon LET sensor  

NASA Technical Reports Server (NTRS)

A new type of real-time radiation monitoring device, RRMD-III, consisting of three double-sided silicon strip detectors (DSSDs), has been developed and tested on-board the Space Shuttle mission STS-84. The test succeeded in measuring the linear energy transfer (LET) distribution over the range of 0.2 keV/micrometer to 600 keV/micrometer for 178 h. The Shuttle cruised at an altitude of 300 to 400 km and an inclination angle of 51.6 degrees for 221.3 h, which is equivalent to the International Space Station orbit. The LET distribution obtained for particles was investigated by separating it into galactic cosmic ray (GCR) particles and trapped particles in the South Atlantic Anomaly (SAA) region. The result shows that the contribution in dose-equivalent due to GCR particles is almost equal to that from trapped particles. The total absorbed dose rate during the mission was 0.611 mGy/day; the effective quality factor, 1.64; and the dose equivalent rate, 0.998 mSv/day. The average absorbed dose rates are 0.158 mGy/min for GCR particles and 3.67 mGy/min for trapped particles. The effective quality factors are 2.48 for GCR particles and 1.19 for trapped particles. The absorbed doses obtained by the RRMD-III and a conventional method using TLD (Mg(2)SiO(4)), which was placed around the RRMD-III were compared. It was found that the TLDs showed a lower efficiency, just 58% of absorbed dose registered by the RRMD-III.

Doke, T.; Hayashi, T.; Kikuchi, J.; Nagaoka, S.; Nakano, T.; Sakaguchi, T.; Terasawa, K.; Badhwar, G. D.

1999-01-01

382

MCNP6 Cosmic-Source Option  

SciTech Connect

MCNP is a Monte Carlo radiation transport code that has been under development for over half a century. Over the last decade, the development team of a high-energy offshoot of MCNP, called MCNPX, has implemented several physics and algorithm improvements important for modeling galactic cosmic-ray (GCR) interactions with matter. In this presentation, we discuss the latest of these improvements, a new Cosmic-Source option, that has been implemented in MCNP6.

McKinney, Gregg W [Los Alamos National Laboratory; Armstrong, Hirotatsu [Los Alamos National Laboratory; James, Michael R [Los Alamos National Laboratory; Clem, John [University of Delaware, BRI; Goldhagen, Paul [DHS, National Urban Security Technology Laboratory

2012-06-19

383

Friction and wear properties of Kevlar pulp reinforced epoxy composites under dry sliding condition  

Microsoft Academic Search

In this work, the friction and wear properties of Kevlar pulp reinforced epoxy composites against GCr15 steel under dry sliding condition were evaluated on a reciprocating ball-on-block UMT-2MT tribometer. The effects of Kevlar pulp content on tribological properties of the composites were investigated. The worn surface morphologies of neat epoxy and its composites were examined by scanning electron microscopy (SEM)

J. Wu; X. H. Cheng

2006-01-01

384

Gas Core Reactor with Magnetohydrodynamic Power System and Cascading Power Cycle  

Microsoft Academic Search

The U.S. Department of Energy initiative Generation IV aim is to produce an entire nuclear energy production system with next-generation features for certification before 2030. A Generation IV-capable system must have superior sustainability, safety and reliability, and economic cost advantages in comparison with third generation light water reactors (LWRs). A gas core reactor (GCR) with magnetohydrodynamic (MHD) power converter and

Blair M. Smith; Samim Anghaie

2004-01-01

385

Galactic Cosmic Ray Modulation near the Heliospheric Current Sheet  

NASA Astrophysics Data System (ADS)

Galactic cosmic rays (GCRs) are modulated by the heliospheric magnetic field (HMF) both over decadal time scales (due to long-term, global HMF variations), and over time scales of a few hours (associated with solar wind structures such as coronal mass ejections or the heliospheric current sheet, HCS). Due to the close association between the HCS, the streamer belt, and the band of slow solar wind, HCS crossings are often associated with corotating interaction regions where fast solar wind catches up and compresses slow solar wind ahead of it. However, not all HCS crossings are associated with strong compressions. In this study we categorize HCS crossings in two ways: Firstly, using the change in magnetic polarity, as either away-to-toward (AT) or toward-to-away (TA) magnetic field directions relative to the Sun and, secondly, using the strength of the associated solar wind compression, determined from the observed plasma density enhancement. For each category, we use superposed epoch analyses to show differences in both solar wind parameters and GCR flux inferred from neutron monitors. For strong-compression HCS crossings, we observe a peak in neutron counts preceding the HCS crossing, followed by a large drop after the crossing, attributable to the so-called `snow-plough' effect. For weak-compression HCS crossings, where magnetic field polarity effects are more readily observable, we instead observe that the neutron counts have a tendency to peak in the away magnetic field sector. By splitting the data by the dominant polarity at each solar polar region, we find that the increase in GCR flux prior to the HCS crossing is primarily from strong compressions in cycles with negative north polar fields due to GCR drift effects. Finally, we report on unexpected differences in GCR behavior between TA weak compressions during opposing polarity cycles.

Thomas, S. R.; Owens, M. J.; Lockwood, M.; Scott, C. J.

2014-07-01

386

Validation of the CATHARE2 code against experimental data from Brayton-cycle plants  

Microsoft Academic Search

In recent years the Commissariat à l’Energie Atomique (CEA) has commissioned a wide range of feasibility studies of future-advanced nuclear reactors, in particular gas-cooled reactors (GCR). The thermohydraulic behaviour of these systems is a key issue for, among other things, the design of the core, the assessment of thermal stresses, and the design of decay heat removal systems. These studies

Fabrice Bentivoglio; Nicolas Tauveron; Geneviève Geffraye; Hervé Gentner

2008-01-01

387

Polymeric Materials With Additives for Durability and Radiation Shielding in Space  

NASA Technical Reports Server (NTRS)

Polymeric materials are attractive for use in space structures because of their light weight and high strength In addition, polymers are made of elements with low atomic numbers (Z), primarily carbon (C), hydrogen (H), oxygen (0), and nitrogen (N) which provide the best shielding from galactic cosmic rays (GCR) (ref. 1). Galactic cosmic rays are composed primarily of nuclei (i.e., fully ionized atoms) plus a contribution of about 2% from electrons and positrons. There is a small but significant component of GCR particles with high charge (Z > 10) and high energy (E >100 GeV) (ref. 2). These so-called HZE particles comprise only 1 to 2% of the cosmic ray fluence but they interact with very high specific ionization and contribute 50% of the long- term dose to humans. The best shield for this radiation would be liquid hydrogen, which is not feasible. For this reason, hydrogen-containing polymers make the most effective practical shields. Moreover, neutrons are formed in the interactions of GCR particles with materials. Neutrons can only lose energy by collisions or reactions with a nucleus since they are uncharged. This is a process that is much less probable than the Coulombic interactions of charged particles. Thus, neutrons migrate far from the site of the reaction in which they were formed. This increases the probability of neutrons reaching humans or electronic equipment. Fast neutrons (> 1 MeV) can interact with silicon chips in electronic equipment resulting in the production of recoil ions which can cause single event upsets (SEU) in sensitive components (ref. 3). Neutrons lose energy most effectively by elastic collisions with light atoms, particularly hydrogen atoms. Therefore, hydrogen-containing polymers are not only effective in interacting with GCR particles; they are also effective in reducing the energy of the neutrons formed in the interactions.

Kiefer, Richard

2011-01-01

388

Radiation Measured with Different Dosimeters for ISS-Expedition 18-19/ULF2 on Board International Space Station during Solar Minimum  

NASA Technical Reports Server (NTRS)

Radiation field of particles in low Earth orbit (LEO) is mainly composed of galactic cosmic rays (GCR), solar energetic particles and particles in SAA (South Atlantic Anomaly). GCR are modulated by solar activity, at the period of solar minimum activity, GCR intensity is at maximum and the main contributor for space radiation is GCR. At present for space radiation measurements conducted by JSC (Johnson Space Center) SRAG (Space Radiation Analysis Group), the preferred active dosimeter sensitive to all LET (Linear Energy Transfer) is the tissue equivalent proportional counter (TEPC); the preferred passive dosimeters are thermoluminescence dosimeters (TLDs) and optically stimulated luminescence dosimeters (OSLDs) sensitive to low LET as well as CR-39 plastic nuclear track detectors (PNTDs) sensitive to high LET. For the method using passive dosimeters, radiation quantities for all LET can be obtained by combining radiation results measured with TLDs/OSLDs and CR-39 PNTDs. TEPC, TLDs/OSLDs and CR-39 detectors were used to measure the radiation field for the ISS (International Space Station) - Expedition 18-19/ULF2 space mission which was conducted from 15 November 2008 to 31 July 2009 - near the period of the recent solar minimum activity. LET spectra (differential and integral fluence, absorbed dose and dose equivalent) and radiation quantities were measured for positions TEPC, TESS (Temporary Sleeping Station, inside the polyethylene lined sleep station), SM-P 327 and 442 (Service Module - Panel 327 and 442). This paper presents radiation LET spectra measured with TEPC and CR-39 PNTDs and radiation dose measured with TLDs/OSLDs as well as the radiation quantities combined from results measured with passive dosimeters.

Zhou, Dazhuang; Gaza, R.; Roed, Y.; Semones, E.; Lee, K.; Steenburgh, R.; Johnson, S.; Flanders, J.; Zapp, N.

2010-01-01

389

Effect of cosmic rays on atmospheric pressure under mountain conditions  

Microsoft Academic Search

The phenomenological model of condensation interaction between galactic cosmic rays (GCRs) and water vapor, which makes it\\u000a possible to estimate atmospheric pressure variations at different altitudes with changing GCR flux, has been developed. It\\u000a has been indicated that pressure should increase at all altitudes in the considered interval (0–5 km above sea level) during\\u000a Forbush decreases. Therefore, the correlation between

M. B. Bogdanov; A. N. Surkov; A. V. Fedorenko

2006-01-01

390

Tribological properties of aligned film of amorphous carbon nanorods on AAO membrane in different environments  

Microsoft Academic Search

The aligned film of amorphous carbon nanorods was synthesized by chemical vapor deposition at 650°C with the Co catalyst on a porous anodic aluminum oxide (AAO) membrane. The morphology and microstructure of the aligned film of amorphous carbon nanorods were examined by field emission SEM, TEM and Raman spectroscopy. The tests sliding against a quenched-and-tempered GCr15 steel were conducted using

J. P. Tu; C. X. Jiang; S. Y. Guo; X. B. Zhao; M. F. Fu

2005-01-01

391

Comparisons of Integrated Radiation Transport Models with Microdosimetry Data in Spaceflight  

NASA Technical Reports Server (NTRS)

Astronauts are exposed to galactic cosmic rays (GCR), trapped protons, and possible solar particle events (SPE) during spaceflight. For such complicated mixtures of radiation types and kinetic energies, tissue equivalent proportional counters (TEPC's) represent a simple time-dependent approach for radiation monitoring. Of interest in radiation protection is the average quality factor of a radiation field defined as a function of linear energy transfer, LET, Q(sub ave)(LET). However TEPC's measure the average quality factors as a function of lineal energy (y), Q(sub ave)(y) defined as the average energy deposition in a volume divided by the average chord length of the volume. Lineal energy, y deviates from LET due to energy straggling, delta-ray escape or entry, and nuclear fragments produced in the detector. Using integrated space radiation models that includes the transport code HZETRN/BRYNTRN, the quantum nuclear interaction model, QMSFRG, and results from Monte-Carlo track simulations of TEPC's response to ions, we consider comparisons of model calculations to TEPC results from NASA missions in low Earth orbit and make predictions for lunar and Mars missions. Good agreement between the model and measured spectra from past NASA missions is found. A finding of this work is that TEPC's values for trapped or solar protons of Q(sub ave)(y) range from 1.9-2.5, overestimating Q(sub ave)(LET), which ranges from 1.4-1.6 with both quantities increasing with shielding depth due to nuclear secondaries Comparisons for the complete GCR spectra show that Q(sub ave)(LET) for GCR is approximately 3.5-4.5, while TEPC's measure 2.9-3.4 for Q(sub ave)(y) with the GCR values decreasing with depth as heavy ions are absorbed in shielding material. Our results support the use of TEPC's for space radiation environmental monitoring when computational analysis is used for proper data interpretation.

Cucinotta, Francis A.; Nikjoo, H.; Kim, M. Y.; Hu, X.; Dicello, J. F.; Pisacane, V. L.

2006-01-01

392

Expression of 11?-hydroxysteroid dehydrogenase type 1 and glucocorticoid receptors in reproductive tissue of male horses at different stages of sexual maturity.  

PubMed

Glucocorticoids (GCs) as mediators of the stress response may affect Leydig cell function by inhibiting either luteinizing hormone receptor expression or testosterone biosynthesis. The isozymes 11?-hydroxysteroid dehydrogenase (11?HSD) 1 and 11?HSD2 control the intracellular cortisol levels. Little is known about the effects of stress on fertility in the equine. The objective of the present study was to determine the presence and cellular localization of glucocorticoid receptors (GCR) and glucocorticoid-metabolizing enzymes (11?HSD1 and 11?HSD2) in equine epididymal and testicular tissue with special regard to sexual maturation. Testicular and epididymal tissue was collected from 21 healthy stallions, and four age groups were designed: pre-pubertal, young, mature and older horses. Immunohistochemistry (IHC) analysis and quantitative real-time PCR (qRT-PCR) were used. Pre-pubertal horses showed higher testicular gene expression of 11?HSD1, 11?HSD2 and GCR than horses of all other groups (p < 0.05). A positive intranuclear immunoreaction for GCR was seen in epithelial cells of caput, corpus and cauda epididymidis and in Leydig cells. Significant differences (p < 0.05) between age groups occurred. The number of Leydig cells staining positive for GCR was highest in immature stallions (p < 0.05). The enzyme 11?HSD1 was localized in epithelial cells of the caput and corpus epididymidis and in Leydig cells. As determined by enzyme assay, nicotinamide adenine dinucleotide (NAD)-dependant dehydrogenase (oxidation) activity was not detected in testicular tissue from immature stallions but in all other age groups (n = 3 per group). Results of this study suggest a contribution of GCs to maturation of male reproductive tissue in horses. In mature stallions, expression of 11?HSD enzymes and the oxidative 11?HSD activity in Leydig cells and epididymal basal and principal cells suggest a protective role on these tissues contributing to physiological intracellular glucocorticoid concentrations. PMID:22734562

Herrera-Luna, C V; Budik, S; Helmreich, M; Walter, I; Aurich, C

2013-04-01

393

IFN-? Reverses IL-2- and IL-4-Mediated T-Cell Steroid Resistance  

PubMed Central

Corticosteroids are the most common therapeutic approach for control of tissue inflammation. Combination IL-2/IL-4 is known to induce T-cell steroid resistance. This can be reversed with IFN-?; however, the mechanism by which this occurs is unknown. In the current study, we found that treatment of peripheral blood mononuclear cells with combination IL-2/IL-4 for 48 hours, but not with IL-2 or IL-4 alone, abrogated dexamethasone (DEX)-induced glucocorticoid receptor (GCR)-? nuclear translocation in both CD4+ and CD8+ T cells. The presence of IL-4 significantly down-regulated IFN-? production by IL-2–stimulated cells. Importantly, addition of IFN-? to the IL-2/IL-4 combination restored GCR? nuclear translocation in response to DEX. Furthermore, DEX-induced mitogen-activated protein kinase (MAPK) phosphatase-1 induction, used as a readout for corticosteroid-induced transactivation, was significantly greater (P < 0.05) in media and IL-2/IL-4/IFN-?–treated conditions compared with IL-2/IL-4–treated cells. The combination of IL-2/IL-4 induced p38 MAPK activation in CD3+ cells (30.5 ± 5.7% cells expressed phospho-p38 MAPK versus no phospho-p38 MAPK expression after media treatment). The presence of the p38 MAPK inhibitor, SB203580, or IFN-? inhibited p38 MAPK phosphorylation and enhanced GCR? nuclear translocation in response to DEX. These data indicate that combination IL-2/IL-4 inhibits GCR? nuclear translocation in human T cells, and this effect is reversed by IFN-? via inhibition of p38 MAPK activation.

Goleva, Elena; Li, Ling-bo; Leung, Donald Y. M.

2009-01-01

394

Turbo-EEPRML: An EEPR4 channel with an error-correcting post-processor designed for 16\\/17 rate quasi-MTR code  

Microsoft Academic Search

An EEPRML channel with a post processor has been developed for compensating for the degradation in performance due to noise correlation. This Turbo-EEPRML is designed for 16\\/17 rate quasi-MTR (QMTR) code. The proposed method has high performance and simple circuitry. Simulation showed that Turbo-EEPRML has a 2.0-2.5 dB coding gain over a conventional EPRML channel for 16\\/17 GCR code

Takushi Nishiya; Kyoko Tsukano; T. Hirai; Takashi Nara; Seiichi Mita

1998-01-01

395

Heavy Ion Testing With Iron at 1 GeV\\/amu  

Microsoft Academic Search

A 1 GeV\\/amu 56Fe ion beam allows for true 90° tilt irradiations of various microelectronic components and reveals relevant upset trends at the GCR flux energy peak. Three SRAMs and an SRAM-based FPGA evaluated at the NASA Space Radiation Effects Laboratory demonstrate that a 90° tilt irradiation yields a unique device response. These tilt angle effects need to be screened

Jonathan A. Pellish; Michael A. Xapsos; Kenneth A. LaBel; P. W. Marshall; D. F. Heidel; K. P. Rodbell; M. C. Hakey; P. E. Dodd; M. R. Shaneyfelt; J. R. Schwank; R. C. Baumann; Xiaowei Deng; Andrew Marshall; B. D. Sierawski; J. D. Black; R. A. Reed; R. D. Schrimpf; H. S. Kim; M. D. Berg; M. J. Campola; M. R. Friendlich; C. E. Perez; A. M. Phan; C. M. Seidleck

2010-01-01

396

Present situation of the operation and maintenance management of nuclear power plants in Japan - Aiming at further improved safety and reliability  

Microsoft Academic Search

In Japan, more than 28 years have passed since the first commercial nuclear power plant started operation, and now, as of September 1993, a total 45 plants with 37,196 MWe are in operation. (24 BWR plants\\/20,914 MWe; 20 PWR plants\\/16, 116 MWe and 1 GCR plant\\/166 MWe). After about 550 reactor - years of operating experience, as of July 1993,

T. Hattori; K. Imoto; K. Akutagawa

1994-01-01

397

Charged Particle Dose Measurements by the Odyssey/MARIE Instrument in Mars Orbit and Model Calculations  

NASA Technical Reports Server (NTRS)

Knowledge of the space radiation environment is crucial both for human space exploration, and robotic space missions. It is likely that human explorers will return to the moon, and then go to Mars within the next thirty years. The radiation environment that they will encounter is a significant obstacle to future exploration, and must be dealt with successfully before longterm human missions outside of the magnetosphere can take place. Shielding technologies and materials must be developed to lower the dose and dose equivalent that human beings will receive on such missions. To begin this development, a fairly complete and accurate understanding of the space environment must be obtained. The major components of the space particle radiation environment that are most hazardous to humans are: galactic cosmic rays (GCR), the particles contained in solar particle events, (SPE), and secondary particles generated in material in the spacecraft itself. The intensity of the GCR varies by roughly a factor of two over the eleven-year solar cycle, inversely with the level of solar activity. These GCR particles are fully stripped nuclei, predominantly protons and helium, but also significant numbers of heavier ions, including carbon, oxygen, and iron. Since the ionization caused by nuclei passing through matter is proportional to the square of its charge (Z=10). The MARIE instrument has been described elsewhere.

Cleghorn, T. F.; Saganti, P. B.; Zeitlin, C.; Cucinotta, F. A.

2004-01-01

398

Monte Carlo transport model comparison with 1A GeV accelerated iron experiment: heavy-ion shielding evaluation of NASA space flight-crew foodstuff.  

PubMed

Deep-space manned flight as a reality depends on a viable solution to the radiation problem. Both acute and chronic radiation health threats are known to exist, with solar particle events as an example of the former and galactic cosmic rays (GCR) of the latter. In this experiment Iron ions of 1A GeV are used to simulate GCR and to determine the secondary radiation field created as the GCR-like particles interact with a thick target. A NASA prepared food pantry locker was subjected to the iron beam and the secondary fluence recorded. A modified version of the Monte Carlo heavy ion transport code developed by Zeitlin at LBNL is compared with experimental fluence. The foodstuff is modeled as mixed nuts as defined by the 71st edition of the Chemical Rubber Company (CRC) Handbook of Physics and Chemistry. The results indicate a good agreement between the experimental data and the model. The agreement between model and experiment is determined using a linear fit to ordered pairs of data. The intercept is forced to zero. The slope fit is 0.825 and the R2 value is 0.429 over the resolved fluence region. The removal of an outlier, Z=14, gives values of 0.888 and 0.705 for slope and R2 respectively. PMID:12539754

Stephens, D L; Townsend, L W; Miller, J; Zeitlin, C; Heilbronn, L

2002-01-01

399

Galactic Cosmic Ray Intensity Response to Interplanetary Coronal Mass Ejections/Magnetic Clouds in 1995-2009  

NASA Technical Reports Server (NTRS)

We summarize the response of the galactic cosmic ray (CGR) intensity to the passage of the more than 300 interplanetary coronal mass ejections (ICMEs) and their associated shocks that passed the Earth during 1995-2009, a period that encompasses the whole of Solar Cycle 23. In approx.80% of cases, the GCR intensity decreased during the passage of these structures, i.e., a "Forbush decrease" occurred, while in approx.10% there was no significant change. In the remaining cases, the GCR intensity increased. Where there was an intensity decrease, minimum intensity was observed inside the ICME in approx.90% of these events. The observations confirm the role of both post-shock regions and ICMEs in the generation of these decreases, consistent with many previous studies, but contrary to the conclusion of Reames, Kahler, and Tylka (Astrophys. 1. Lett. 700, L199, 2009) who, from examining a subset of ICMEs with flux-rope-like magnetic fields (magnetic clouds) argued that these are "open structures" that allow free access of particles including GCRs to their interior. In fact, we find that magnetic clouds are more likely to participate in the deepest GCR decreases than ICMEs that are not magnetic clouds.

Richardson, I. G.; Cane, H. V.

2011-01-01

400

Physical basis of radiation protection in space travel  

NASA Astrophysics Data System (ADS)

The health risks of space radiation are arguably the most serious challenge to space exploration, possibly preventing these missions due to safety concerns or increasing their costs to amounts beyond what would be acceptable. Radiation in space is substantially different from Earth: high-energy (E) and charge (Z) particles (HZE) provide the main contribution to the equivalent dose in deep space, whereas ? rays and low-energy ? particles are major contributors on Earth. This difference causes a high uncertainty on the estimated radiation health risk (including cancer and noncancer effects), and makes protection extremely difficult. In fact, shielding is very difficult in space: the very high energy of the cosmic rays and the severe mass constraints in spaceflight represent a serious hindrance to effective shielding. Here the physical basis of space radiation protection is described, including the most recent achievements in space radiation transport codes and shielding approaches. Although deterministic and Monte Carlo transport codes can now describe well the interaction of cosmic rays with matter, more accurate double-differential nuclear cross sections are needed to improve the codes. Energy deposition in biological molecules and related effects should also be developed to achieve accurate risk models for long-term exploratory missions. Passive shielding can be effective for solar particle events; however, it is limited for galactic cosmic rays (GCR). Active shielding would have to overcome challenging technical hurdles to protect against GCR. Thus, improved risk assessment and genetic and biomedical approaches are a more likely solution to GCR radiation protection issues.

Durante, Marco; Cucinotta, Francis A.

2011-10-01

401

Spectrum and ionization rate of low-energy Galactic cosmic rays  

NASA Astrophysics Data System (ADS)

We consider the rate of ionization of diffuse and molecular clouds in the interstellar medium by Galactic cosmic rays (GCRs) in order to constrain its low-energy spectrum. We extrapolate the GCR spectrum obtained from PAMELA at high energies (?200 GeV nucleon-1) and a recently derived GCR proton flux at 1-200 GeV from observations of gamma-rays from molecular clouds, and find that the observed average Galactic ionization rate can be reconciled with this GCR spectrum if there is a low-energy cut-off for protons at 10-100 MeV. We also identify the flattening below a few GeV as being due to (a) decrease of the diffusion coefficient and dominance of convective loss at low energy and (b) the expected break in energy spectrum for a constant spectral index in momentum. We show that the inferred CR proton spectrum of ? for Ekin? few GeV is consistent with a power-law spectrum in momentum p-2.45± 0.4, which we identify as the spectrum at source. Diffusion loss at higher energies then introduces a steepening by E-? with ?˜ 1/3, making it consistent with high-energy measurements.

Nath, Biman B.; Gupta, Nayantara; Biermann, Peter L.

2012-09-01

402

ANISOTROPY AS A PROBE OF THE GALACTIC COSMIC-RAY PROPAGATION AND HALO MAGNETIC FIELD  

SciTech Connect

The anisotropy of cosmic rays (CRs) in the solar vicinity is generally attributed to CR streaming due to the discrete distribution of CR sources or local magnetic field modulation. Recently, the two-dimensional large-scale CR anisotropy has been measured by many experiments in the TeV-PeV energy range in both hemispheres. The tail-in excess along the tangential direction of the local spiral arm and the loss cone deficit pointing to the north Galactic pole direction agree with what have been obtained in tens to hundreds of GeV. The persistence of the two large-scale anisotropy structures in such a wide energy range suggests that the anisotropy might be due to global streaming of the Galactic CRs (GCRs). This work tries to extend the observed CR anisotropy picture from the solar system to the whole galaxy. In such a case, we can find a new interesting signature, a loop of GCR streaming, of the GCR propagation. We further calculate the overall GCR streaming induced magnetic field, and find a qualitative consistency with the observed structure of the halo magnetic field.

Qu, Xiao-bo; Zhang, Yi; Liu, Cheng; Hu, Hong-bo [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Xue, Liang, E-mail: zhangyi@mail.ihep.ac.cn [School of Physics, Shandong University, Ji'nan 250100 (China)

2012-05-01

403

A temporal forecast of radiation environments for future space exploration missions.  

PubMed

The understanding of future space radiation environments is an important goal for space mission operations, design, and risk assessment. We have developed a solar cycle statistical model in which sunspot number is coupled to space-related quantities, such as the galactic cosmic radiation (GCR) deceleration potential (phi) and the mean occurrence frequency of solar particle events (SPEs). Future GCR fluxes were derived from a predictive model, in which the temporal dependence represented by phi was derived from GCR flux and ground-based Climax neutron monitor rate measurements over the last four decades. These results showed that the point dose equivalent inside a typical spacecraft in interplanetary space was influenced by solar modulation by up to a factor of three. It also has been shown that a strong relationship exists between large SPE occurrences and phi. For future space exploration missions, cumulative probabilities of SPEs at various integral fluence levels during short-period missions were defined using a database of proton fluences of past SPEs. Analytic energy spectra of SPEs at different ranks of the integral fluences for energies greater than 30 MeV were constructed over broad energy ranges extending out to GeV for the analysis of representative exposure levels at those fluences. Results will guide the design of protection systems for astronauts during future space exploration missions. PMID:17165049

Kim, Myung-Hee Y; Cucinotta, Francis A; Wilson, John W

2007-06-01

404

Space Radiation Cancer Risks and Uncertainities for Different Mission Time Periods  

NASA Technical Reports Server (NTRS)

Space radiation consists of solar particle events (SPEs), comprised largely of medium energy protons (less than several hundred MeV); and galactic cosmic ray (GCR), which includes high energy protons and high charge and energy (HZE) nuclei. For long duration missions, space radiation presents significant health risks including cancer mortality. Probabilistic risk assessment (PRA) is essential for radiation protection of crews on long term space missions outside of the protection of the Earth s magnetic field and for optimization of mission planning and costs. For the assessment of organ dosimetric quantities and cancer risks, the particle spectra at each critical body organs must be characterized. In implementing a PRA approach, a statistical model of SPE fluence was developed, because the individual SPE occurrences themselves are random in nature while the frequency distribution of SPEs depends strongly upon the phase within the solar activity cycle. Spectral variability of SPEs was also examined, because the detailed energy spectra of protons are important especially at high energy levels for assessing the cancer risk associated with energetic particles for large events. An overall cumulative probability of a GCR environment for a specified mission period was estimated for the temporal characterization of the GCR environment represented by the deceleration potential (theta). Finally, this probabilistic approach to space radiation cancer risk was coupled with a model of the radiobiological factors and uncertainties in projecting cancer risks. Probabilities of fatal cancer risk and 95% confidence intervals will be reported for various periods of space missions.

Kim,Myung-Hee Y.; Cucinotta, Francis A.

2012-01-01

405

Use of Apollo 17 Epoch Neutron Spectrum as a Benchmark in Testing LEND Collimated Sensor  

NASA Technical Reports Server (NTRS)

The Apollo 17 neutron experiment LPNE provided a unique set of data on production of neutrons in the Lunar soil bombarded by Galactic Cosmic Rays (GCR). It serves as valuable "ground-truth" in the age of orbital remote sensing. We used the neutron data attributed to Apollo 17 epoch as a benchmark for testing the LEND's collimated sensor, as introduced by the geometry of collimator and efficiency of He3 counters. The latter is defined by the size of gas counter and pressure inside it. The intensity and energy spectrum of neutrons escaping the lunar surface are dependent on incident flux of Galactic Cosmic Rays (GCR) whose variability is associated with Solar Cycle and its peculiarities. We obtain first the share of neutrons entering through the field of view of collimator as a fraction of the total neutron flux by using the angular distribution of neutron exiting the Moon described by our Monte Carlo code. We computed next the count rate of the 3He sensor by using the neutron energy spectrum from McKinney et al. [JGR, 2006] and by consider geometry and gas pressure of the LEND sensor. Finally the neutron count rate obtained for the Apollo 17 epoch characterized by intermediate solar activity was adjusted to the LRO epoch characterized by low solar activity. It has been done by taking into account solar modulation potential, which affects the GCR flux, and in turn changes the neutron albedo flux.

Chin, Gordon; Sagdeev, R.; Milikh, G.

2011-01-01

406

Nuclear fragmentation cross sections for NASA database development  

SciTech Connect

Heavy ions with energies of hundreds to thousands of MeV/nucleon are present in the Galactic Cosmic Rays and will be a source of risk to astronaut health when long-duration crewed missions are undertaken. Nuclear interactions of these GCR ions in shielding materials must be accurately modeled by transport codes in order to estimate the dose and dose equivalent at points inside a spacecraft. Uncertainties in the nuclear fragmentation cross sections are propagated into these estimates, and the overall uncertainties increase as shielding depth increases. A program of fragmentation cross section measurements has therefore been undertaken to reduce these uncertainties, using GCR-like ion species and energies in particle accelerators in the United States, at the Brookhaven National Laboratory's Alternating Gradient Synchrotron (AGS) and in Japan at the National Institute of Radiological Science's Heavy Ion Medical Accelerator in Chiba (HIMAC). An extensive set of data has been obtained with beams ranging from helium to iron and including most of the species that are prominent in the GCR.

Zeitlin, Cary J.; Heilbronn, Lawrence H.; Miller, Jack; Fukumura, Akifumi; Iwata, Yoshi; Murakami, Takeshi; MacGibbon, Jane; Pinsky, Lawrence; Wilson, Thomas

2001-08-24

407

Further development of the ion cross section for single event upset: model (HICUP)  

SciTech Connect

The HICUP models are shown to be useful tools for both analyzing cross section data and performing upset rate calculations, thereby allowing the cross section concept to be used in both areas. The angular dependent HICUP model is developed from the RPP geometry and the Weibull density function. It is compared with angular cross section data, showing good agreement. The HICUP model is used to derive the correct scaling laws for transforming cross section data taken off-normal to normal incidence. The HICUP scaling reconciles two previously proposed inverse cosine scaling corrections which are shown to be asymptotic forms of the HICUP scaling. The angle-integrated form, I-HICUP, is developed and used in Galactic Cosmic Ray (GCR) upset rate calculations on several devices. Results are nearly identical to SPACE RADIATION{trademark} calculations. I-HICUP is used to perform an uncertainty analysis of GCR upset rate, examining the sensitivity to uncertainties in the input parameters. The GCR upset rate shows the greatest sensitivity to upset threshold, device depth (and funnel depth if applicable), and saturation cross section, the least sensitivity to RPP length-to-width aspect ratio. The other Weibull parameters, width, W, and shape, b, are of intermediate sensitivity.

Connell, L.W.; Sexton, F.W.; Prinja, A.K.

1995-07-01

408

Materials for Shielding Astronauts from the Hazards of Space Radiations  

NASA Technical Reports Server (NTRS)

One major obstacle to human space exploration is the possible limitations imposed by the adverse effects of long-term exposure to the space environment. Even before human spaceflight began, the potentially brief exposure of astronauts to the very intense random solar energetic particle (SEP) events was of great concern. A new challenge appears in deep space exploration from exposure to the low-intensity heavy-ion flux of the galactic cosmic rays (GCR) since the missions are of long duration and the accumulated exposures can be high. Because cancer induction rates increase behind low to rather large thickness of aluminum shielding according to available biological data on mammalian exposures to GCR like ions, the shield requirements for a Mars mission are prohibitively expensive in terms of mission launch costs. Preliminary studies indicate that materials with high hydrogen content and low atomic number constituents are most efficient in protecting the astronauts. This occurs for two reasons: the hydrogen is efficient in breaking up the heavy GCR ions into smaller less damaging fragments and the light constituents produce few secondary radiations (especially few biologically damaging neutrons). An overview of the materials related issues and their impact on human space exploration will be given.

Wilson, J. W.; Cucinotta, F. A.; Miller, J.; Shinn, J. L.; Thibeault, S. A.; Singleterry, R. C.; Simonsen, L. C.; Kim, M. H.

1997-01-01

409

Full Mission Astronaut Radiation Exposure Assessments for Long Duration Lunar Surface Missions  

NASA Technical Reports Server (NTRS)

Risk to astronauts due to ionizing radiation exposure is a primary concern for missions beyond Low Earth Orbit (LEO) and will drive mission architecture requirements, mission timelines, and operational practices. For short missions, radiation risk is dominated by the possibility of a large Solar Particle Event (SPE). Longer duration missions have both SPE and Galactic Cosmic Ray (GCR) risks. SPE exposure can contribute significantly toward cancer induction in combination with GCR. As mission duration increases, mitigation strategies must address the combined risks from SPE and GCR exposure. In this paper, full mission exposure assessments were performed for the proposed long duration lunar surface mission scenarios. In order to accomplish these assessments, previously developed radiation shielding models for a proposed lunar habitat and rover were utilized. End-to-End mission exposure assessments were performed by first calculating exposure rates for locations in the habitat, rover, and during Extra-Vehicular Activities (EVA). Subsequently, total mission exposures were evaluated for the proposed timelines. Mission exposure results, assessed in terms of effective dose, are presented for the proposed timelines and recommendations are made for improved astronaut shielding and safer operational practices.

Adamczyk, Anne; Clowdsley, Martha; Qualls, Garry; Blattnig, Steve; Lee, Kerry; Fry, Dan; Stoffle, Nicholas; Simonsen, Lisa; Slaba, Tony; Walker, Steven; Zapp, Edward

2011-01-01

410

Radiation considerations for interplanetary missions  

NASA Astrophysics Data System (ADS)

Galactic cosmic radiation (GCR) poses a serious radiation hazard for long-duration missions. In designing a lunar habitat or Mars transfer vehicle, the worst-case radiation exposure determines shielding thickness and, hence, the weight of spacecraft. Using the spherically symmetric diffusion theory of the solar modulation of GCR, it was possible to use data on the differential energy spectra of hydrogen, helium, oxygen, and iron from 1954 to 1989 to show that the flux at 1 A.U. is determined by the diffusion parameter, K, which is a function of the time in the solar cycle. This analysis also showed that the solar minimum of 1976 to 1977 was the deepest minimum in the last 37 years. Using this theory, we have obtained the GCR spectra for all the nuclei and calculated the depth-dose as a function of aluminum shield thickness. Using the ICRP-26 definition of the quality factor, it is shown that the shielding required to stay below the LEO recommended annual limit of 50 cSv is 17.5 (+8, -3), g/sq cm of aluminum; if the limit is raised to 60 cSv, the required shielding is 9 (5, -1.5) g/sq cm. We also discuss the issues and shielding needs for protection against solar particle events.

Badwar, Gautam D.; Oneill, Patrick M.; Cucinotta, Francis A.

1993-02-01

411

Probabilistic Assessment of Radiation Risk for Astronauts in Space Missions  

NASA Technical Reports Server (NTRS)

Accurate predictions of the health risks to astronauts from space radiation exposure are necessary for enabling future lunar and Mars missions. Space radiation consists of solar particle events (SPEs), comprised largely of medium energy protons, (less than 100 MeV); and galactic cosmic rays (GCR), which include protons and heavy ions of higher energies. While the expected frequency of SPEs is strongly influenced by the solar activity cycle, SPE occurrences themselves are random in nature. A solar modulation model has been developed for the temporal characterization of the GCR environment, which is represented by the deceleration potential, phi. The risk of radiation exposure from SPEs during extra-vehicular activities (EVAs) or in lightly shielded vehicles is a major concern for radiation protection, including determining the shielding and operational requirements for astronauts and hardware. To support the probabilistic risk assessment for EVAs, which would be up to 15% of crew time on lunar missions, we estimated the probability of SPE occurrence as a function of time within a solar cycle using a nonhomogeneous Poisson model to fit the historical database of measurements of protons with energy > 30 MeV, (phi)30. The resultant organ doses and dose equivalents, as well as effective whole body doses for acute and cancer risk estimations are analyzed for a conceptual habitat module and a lunar rover during defined space mission periods. This probabilistic approach to radiation risk assessment from SPE and GCR is in support of mission design and operational planning to manage radiation risks for space exploration.

Kim, Myung-Hee; DeAngelis, Giovanni; Cucinotta, Francis A.

2009-01-01

412

The Martian Radiation Environment Experiment: Overview and First Results  

NASA Astrophysics Data System (ADS)

The Martian Radiation Environment Experiment (MARIE) is designed to measure charged particle radiation in Mars orbit as a precursor to possible human exploration. Charged nuclear particles originating from galactic sources (the Galactic Cosmic Rays, or GCR) are known to pose a health risk from chronic exposures, which will be inevitable during transit and during prolonged stays on the Martian surface. Solar energetic particles (SEP) are an additional source of risk, which can be acute during high-intensity solar events. Astronauts in low-earth orbit receive considerable protection against charged particles from the geomagnetosphere, which deflects many particles towards the poles. Because Mars lacks a strong magnetic field, astronauts in orbit or on the surface will not be comparably protected. MARIE is designed to measure a wide spectrum of particles, from the high-energy heavy ions that comprise the GCR to the low-energy protons (with 10's of MeV of kinetic energy) prevalent among SEP. MARIE provides a new observation point for SEP, and comparison to sensors in near-Earth orbit may shed light on fundamental issues in solar physics. We will present an overview of MARIE's measurement capabilities, as well as initial charged-particle dose-rate data, which will be compared to predictions of current models of the GCR.

Zeitlin, C.; Cucinotta, F. A.; Cleghorn, T. F.; Saganti, P.; Pinsky, L. S.; Lee, K. T.; Atwell, W. A.

2002-09-01

413

Galactic Cosmic Ray Intensity Response to Interplanetary Coronal Mass Ejections/Magnetic Clouds in 1995 - 2009  

NASA Astrophysics Data System (ADS)

We summarize the response of the galactic cosmic ray (CGR) intensity to the passage of the more than 300 interplanetary coronal mass ejections (ICMEs) and their associated shocks that passed the Earth during 1995 - 2009, a period that encompasses the whole of Solar Cycle 23. In ˜ 80% of cases, the GCR intensity decreased during the passage of these structures, i.e., a "Forbush decrease" occurred, while in ˜ 10% there was no significant change. In the remaining cases, the GCR intensity increased. Where there was an intensity decrease, minimum intensity was observed inside the ICME in ˜ 90% of these events. The observations confirm the role of both post-shock regions and ICMEs in the generation of these decreases, consistent with many previous studies, but contrary to the conclusion of Reames, Kahler, and Tylka ( Astrophys. J. Lett. 700, L199, 2009) who, from examining a subset of ICMEs with flux-rope-like magnetic fields (magnetic clouds) argued that these are "open structures" that allow free access of particles including GCRs to their interior. In fact, we find that magnetic clouds are more likely to participate in the deepest GCR decreases than ICMEs that are not magnetic clouds.

Richardson, I. G.; Cane, H. V.

2011-06-01

414

A screen for suppressors of gross chromosomal rearrangements identifies a conserved role for PLP in preventing DNA lesions.  

PubMed

Genome instability is a hallmark of cancer cells. One class of genome aberrations prevalent in tumor cells is termed gross chromosomal rearrangements (GCRs). GCRs comprise chromosome translocations, amplifications, inversions, deletion of whole chromosome arms, and interstitial deletions. Here, we report the results of a genome-wide screen in Saccharomyces cerevisiae aimed at identifying novel suppressors of GCR formation. The most potent novel GCR suppressor identified is BUD16, the gene coding for yeast pyridoxal kinase (Pdxk), a key enzyme in the metabolism of pyridoxal 5' phosphate (PLP), the biologically active form of vitamin B6. We show that Pdxk potently suppresses GCR events by curtailing the appearance of DNA lesions during the cell cycle. We also show that pharmacological inhibition of Pdxk in human cells leads to the production of DSBs and activation of the DNA damage checkpoint. Finally, our evidence suggests that PLP deficiency threatens genome integrity, most likely via its role in dTMP biosynthesis, as Pdxk-deficient cells accumulate uracil in their nuclear DNA and are sensitive to inhibition of ribonucleotide reductase. Since P