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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

Mixed-field GCR Simulations for Radiobiological Research Using Ground Based Accelerators  

NASA Technical Reports Server (NTRS)

Space radiation is comprised of a large number of particle types and energies, which have differential ionization power from high energy protons to high charge and energy (HZE) particles and secondary neutrons produced by galactic cosmic rays (GCR). Ground based accelerators such as the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL) are used to simulate space radiation for radiobiology research and dosimetry, electronics parts, and shielding testing using mono-energetic beams for single ion species. As a tool to support research on new risk assessment models, we have developed a stochastic model of heavy ion beams and space radiation effects, the GCR Event-based Risk Model computer code (GERMcode). For radiobiological research on mixed-field space radiation, a new GCR simulator at NSRL is proposed. The NSRL-GCR simulator, which implements the rapid switching mode and the higher energy beam extraction to 1.5 GeV/u, can integrate multiple ions into a single simulation to create GCR Z-spectrum in major energy bins. After considering the GCR environment and energy limitations of NSRL, a GCR reference field is proposed after extensive simulation studies using the GERMcode. The GCR reference field is shown to reproduce the Z and LET spectra of GCR behind shielding within 20% accuracy compared to simulated full GCR environments behind shielding. A major challenge for space radiobiology research is to consider chronic GCR exposure of up to 3-years in relation to simulations with cell and animal models of human risks. We discuss possible approaches to map important biological time scales in experimental models using ground-based simulation with extended exposure of up to a few weeks and fractionation approaches at a GCR simulator.

Kim, Myung-Hee Y.; Rusek, Adam; Cucinotta, Francis A.

2014-01-01

3

Mixed-field GCR Simulations for Radiobiological Research using Ground Based Accelerators  

NASA Astrophysics Data System (ADS)

Space radiation is comprised of a large number of particle types and energies, which have differential ionization power from high energy protons to high charge and energy (HZE) particles and secondary neutrons produced by galactic cosmic rays (GCR). Ground based accelerators such as the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL) are used to simulate space radiation for radiobiology research and dosimetry, electronics parts, and shielding testing using mono-energetic beams for single ion species. As a tool to support research on new risk assessment models, we have developed a stochastic model of heavy ion beams and space radiation effects, the GCR Event-based Risk Model computer code (GERMcode). For radiobiological research on mixed-field space radiation, a new GCR simulator at NSRL is proposed. The NSRL-GCR simulator, which implements the rapid switching mode and the higher energy beam extraction to 1.5 GeV/u, can integrate multiple ions into a single simulation to create GCR Z-spectrum in major energy bins. After considering the GCR environment and energy limitations of NSRL, a GCR reference field is proposed after extensive simulation studies using the GERMcode. The GCR reference field is shown to reproduce the Z and LET spectra of GCR behind shielding within 20 percents accuracy compared to simulated full GCR environments behind shielding. A major challenge for space radiobiology research is to consider chronic GCR exposure of up to 3-years in relation to simulations with cell and animal models of human risks. We discuss possible approaches to map important biological time scales in experimental models using ground-based simulation with extended exposure of up to a few weeks and fractionation approaches at a GCR simulator.

Kim, Myung-Hee Y.; Rusek, Adam; Cucinotta, Francis

4

Overview of the Graphical User Interface for the GERM Code (GCR Event-Based Risk Model  

NASA Technical Reports Server (NTRS)

The descriptions of biophysical events from heavy ions are of interest in radiobiology, cancer therapy, and space exploration. The biophysical description of the passage of heavy ions in tissue and shielding materials is best described by a stochastic approach that includes both ion track structure and nuclear interactions. A new computer model called the GCR Event-based Risk Model (GERM) code was developed for the description of biophysical events from heavy ion beams at the NASA Space Radiation Laboratory (NSRL). The GERM code calculates basic physical and biophysical quantities of high-energy protons and heavy ions that have been studied at NSRL for the purpose of simulating space radiobiological effects. For mono-energetic beams, the code evaluates the linear-energy transfer (LET), range (R), and absorption in tissue equivalent material for a given Charge (Z), Mass Number (A) and kinetic energy (E) of an ion. In addition, a set of biophysical properties are evaluated such as the Poisson distribution of ion or delta-ray hits for a specified cellular area, cell survival curves, and mutation and tumor probabilities. The GERM code also 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. The contributions from primary ion and nuclear secondaries are evaluated. The GERM code 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. The QMSFRG model has been shown to be in excellent agreement with available experimental data for nuclear fragmentation cross sections, and has been used by the GERM code for application to thick target experiments. The GERM code provides scientists participating in NSRL experiments with the data needed for the interpretation of their experiments, including the ability to model the beam line, the shielding of samples and sample holders, and the estimates of basic physical and biological outputs of the designed experiments. We present an overview of the GERM code GUI, as well as providing training applications.

Kim, Myung-Hee; Cucinotta, Francis A.

2010-01-01

5

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

6

Mutations in Gcr1, a Transcriptional Activator of Saccharomyces Cerevisiae Glycolytic Genes, Function as Suppressors of Gcr2 Mutations  

PubMed Central

The Saccharomyces cerevisiae GCR1 and GCR2 genes affect expression of most of the glycolytic genes. Evidence for Gcr1p/Gcr2p interaction has been presented earlier and is now supported by the isolation of mutations in Gcr1p suppressing gcr2, as assessed by growth and enzyme assay. Four specific mutation sites were identified. Together with use of the two-hybrid system of FIELDS and SONG, they show that Gcr1p in its N-terminal half has a potential transcriptional activating function as well as elements for interaction with Gcr2p, which perhaps acts normally to expose an otherwise cryptic activation domain on Gcr1p. Complementation of various gcr1 mutant alleles and results with the two-hybrid system also indicate that Gcr1p itself normally functions as an oligomer. PMID:7713414

Uemura, H.; Jigami, Y.

1995-01-01

7

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

8

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

9

p.2--GCR: President's Reflection, Welcome by New GCR President and Treasurer  

E-print Network

BBQ Michaelmas 20092010 Summer at last? The sun shines on the Ustinov BBQ Easter 2009-2010 Photo the study room, Howlands shop, and the GCR to name a few), and I made a point of attending all the events I, the older accommodation blocks, and revamping the Howlands shop. Those of you who live in college

Wirosoetisno, Djoko

10

A Parallel Implementation of the Block Preconditioned GCR Method  

E-print Network

with GCR. To precondition the GCR method a block Gauss-Jacobi method is used. Approximate solvers are used methods 1 Introduction This paper addresses the parallel implementation of a Krylov accelerated block Gauss-Jacobi method for the DeFT Navier-Stokes solver described in [15], and is the continuation of work

Vuik, Kees

11

Event-Based Personal Retrieval.  

ERIC Educational Resources Information Center

In personal information retrieval, items are associated with events and can be accessed by their relationship to events as well as content. Describes two early projects and a prototype graphical event-based retrieval system comprising file changes, mail messages, active badge sightings, video snapshots, desk diary entries, notes, weather reports…

Bovey, J. D.

1996-01-01

12

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

13

Role of GCR2 in transcriptional activation of yeast glycolytic genes.  

PubMed Central

The Saccharomyces cerevisiae GCR2 gene affects expression of most of the glycolytic genes. We report the nucleotide sequence of GCR2, which can potentially encode a 58,061-Da protein. There is a small cluster of asparagines near the center and a C-terminal region that would be highly charged but overall neutral. Fairly homologous regions were found between Gcr2 and Gcr1 proteins. To test potential interactions, the genetic method of S. Fields and O. Song (Nature [London] 340:245-246, 1989), which uses protein fusions of candidate gene products with, respectively, the N-terminal DNA-binding domain of Gal4 and the C-terminal activation domain II, assessing restoration of Gal4 function, was used. In a delta gal4 delta gal80 strain, double transformation by plasmids containing, respectively, a Gal4 (transcription-activating region)/Gcr1 fusion and a Gal4 (DNA-binding domain)/Gcr2 fusion activated lacZ expression from an integrated GAL1/lacZ fusion, indicating reconstitution of functional Gal4 through the interaction of Gcr1 and Gcr2 proteins. The Gal4 (transcription-activating region)/Gcr1 fusion protein alone complemented the defects of both gcr1 and gcr2 strains. Furthermore, a Rap1/Gcr2 fusion protein partially complemented the defects of gcr1 strains. These results suggest that Gcr2 has transcriptional activation activity and that the GCR1 and GCR2 gene products function together. PMID:1508187

Uemura, H; Jigami, Y

1992-01-01

14

p. 2--GCR Executive columns p.4--Arrivals and Returns  

E-print Network

.17--Academic p.23--Alumni p.28--Cultural p.30--Off the Hill p.39--Clubs & Societies p.41--Funnies in the creation of several new clubs and societies under the aegis of the GCR. To help clubs and societies as much is fairer, more consistent, and should ensure clubs and societies are better supported than ever before

Wirosoetisno, Djoko

15

GCR-induced Photon Luminescence of the Moon  

NASA Astrophysics Data System (ADS)

A GCR-induced photon luminescence is demonstrated to exist on the Moon. Its spectrum is derived and shown to exist in the upper X-ray and lower gamma-ray portion of the electromagnetic spectrum - detectable during total lunar night (no sunlight, Earthshine).

Lee, K. T.; Wilson, T. L.

2008-03-01

16

p. 2--GCR reports p.5--Social events  

E-print Network

have a think about it yourself. In between now and then? A few things. I hope I'm still in post when of amusing speeches (well, perhaps the occasional outing for Burns Night), the opportunity to study lodged somewhere in the back of my mind. If you think you would be interested in standing for GCR

Wirosoetisno, Djoko

17

The gcr (glycolysis regulation) mutation of Saccharomyces cerevisiae.  

PubMed

gcr is a mutation considerably decreasing the assayed amounts of most glycolysis enzymes in Saccharomyces cerevisiae (Clifton, D., Weinstock, S. B., and Fraenkel, D. G. (1978) Genetics 88, 1-11). We show here that although in the wild type strain the amounts of these enzymes do not greatly differ between cells from different media, in the gcr mutant strain most of the enzyme amounts are 5% or less, relative to wild type, from cells grown without sugars, but 20-50% from cells grown with sugars. Lower relative values were found for phosphoglycerate mutase and enolase. A corresponding alteration in the mutant in the intensities of several major protein bands could even be seen in stained gels after electrophoresis of crude extracts: the profiles were otherwise normal. Results of titration of phosphoglycerate kinase with antibody accorded with activity. Transfer of cells between the two types of media did not lead to a more rapid adjustment of enzyme amounts than expected from the steady state levels. gcr is not allelic to GPM (the gene for phosphoglycerate mutase) or to RNA1 (which affects transport of RNA from the nucleus). Translation of total RNA in a rabbit reticulocyte lysate gave a pattern of polypeptides similar to the in vivo one. Thus, gcr is likely to affect somehow mRNA synthesis or lifetime for a discrete number of proteins. PMID:7031056

Clifton, D; Fraenkel, D G

1981-12-25

18

Glucose Metabolism in gcr Mutants of Saccharomyces cerevisiae  

PubMed Central

A gcr2 null mutant of Saccharomyces cerevisiae grows well on glucose in spite of its lower level of glycolytic enzymes between triose phosphates and pyruvate. A quantitative analysis shows that these levels are adequate to the flux but glycerate phosphates are elevated. PMID:10419980

Uemura, H.; Fraenkel, D. G.

1999-01-01

19

Host Event Based Network Monitoring  

SciTech Connect

The purpose of INL’s research on this project is to demonstrate the feasibility of a host event based network monitoring tool and the effects on host performance. Current host based network monitoring tools work on polling which can miss activity if it occurs between polls. Instead of polling, a tool could be developed that makes use of event APIs in the operating system to receive asynchronous notifications of network activity. Analysis and logging of these events will allow the tool to construct the complete real-time and historical network configuration of the host while the tool is running. This research focused on three major operating systems commonly used by SCADA systems: Linux, WindowsXP, and Windows7. Windows 7 offers two paths that have minimal impact on the system and should be seriously considered. First is the new Windows Event Logging API, and, second, Windows 7 offers the ALE API within WFP. Any future work should focus on these methods.

Jonathan Chugg

2013-01-01

20

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

21

Event based Control for Distributed Systemsy  

E-print Network

Event based Control for Distributed Systemsy Karl H. Johansson and Maben Rabi ACCESS Linnaeus CentreACCESS Linnaeus Centre Electrical Engineering, Royal Institute of Technology Stockholm Sweden and Estimation June 2 5, 2009, Noordwijkerhout ACCESS Linnaeus CentreACCESS Linnaeus Centre · One of Europes

Johansson, Karl Henrik

22

Through Event-Based Haptic Feedback  

Microsoft Academic Search

Tapping on surfaces in a typical virtual en- vironment feels like contact with soft foam rather than a hard object. The realism of such interactions can be dramatically improved by superimposing event-based, high-frequency transient forces over traditional positio n- based feedback. When scaled by impact velocity, hand- tuned pulses and decaying sinusoids produce haptic cues that resemble those experienced during

Katherine J. Kuchenbecker; Jonathan Fiene; Gunter Niemeyer

23

Asynchronous event-based hebbian epipolar geometry.  

PubMed

Epipolar geometry, the cornerstone of perspective stereo vision, has been studied extensively since the advent of computer vision. Establishing such a geometric constraint is of primary importance, as it allows the recovery of the 3-D structure of scenes. Estimating the epipolar constraints of nonperspective stereo is difficult, they can no longer be defined because of the complexity of the sensor geometry. This paper will show that these limitations are, to some extent, a consequence of the static image frames commonly used in vision. The conventional frame-based approach suffers from a lack of the dynamics present in natural scenes. We introduce the use of neuromorphic event-based--rather than frame-based--vision sensors for perspective stereo vision. This type of sensor uses the dimension of time as the main conveyor of information. In this paper, we present a model for asynchronous event-based vision, which is then used to derive a general new concept of epipolar geometry linked to the temporal activation of pixels. Practical experiments demonstrate the validity of the approach, solving the problem of estimating the fundamental matrix applied, in a first stage, to classic perspective vision and then to more general cameras. Furthermore, this paper shows that the properties of event-based vision sensors allow the exploration of not-yet-defined geometric relationships, finally, we provide a definition of general epipolar geometry deployable to almost any visual sensor. PMID:21954205

Benosman, Ryad; Ieng, Sio-Hoï; Rogister, Paul; Posch, Christoph

2011-11-01

24

Event-based Stabilization of Nonlinear Time-Delay Systems  

E-print Network

Event-based Stabilization of Nonlinear Time-Delay Systems Sylvain Durand Nicolas Marchand J: Event-based control, Nonlinear systems, Time delay, Stabilization. INTRODUCTION The classical (time@durandchamontin.fr Abstract: In this paper, a universal formula is proposed for event-based stabilization of nonlinear time-delay

Paris-Sud XI, Université de

25

Flexible gray component replacement (GCR) based on CIE L*a*b*  

NASA Astrophysics Data System (ADS)

To improve the color fidelity of 4 color reproduction and to increase the flexibility of Gray Component Replacement (GCR) for the text and continuous images, a novel GCR algorithm based on CIE L*a*b* signals is proposed. The algorithm consist of (1) maximum (achromatic) black determination part, (2) black adjustment part based on chroma, and (3) 3 color determination part. On this configuration, black signal is determined ahead of MCY signals, and the freedom of 3 input i.e L*a*b* 4 output i.e. CMYBk conversion is concentrated in (2). By using xerographic color printer, by neural network technique for resolving this, the algorithm is examined. As a result, it is shown that the algorithm can conserve the color fidelity in any GCR rate, and which is applicable on both of text and continuous images.

Ogatsu, Hitoshi; Murai, Kazumasa; Kita, Shinji

1995-04-01

26

On the GCR intensity around the activity maxima for solar cycles 21-24  

NASA Astrophysics Data System (ADS)

Now we are in the end of the maximum phase of solar cycle (SC) 24, in many aspects anomalous when compared with solar cycles of the second half of the 20-th century. The corresponding phase in the GCR intensity cycle should also be in progress. Earlier we suggested the classification of the heliospheric magnetic field (HMF) polarity distributions and assumed that the process of the inversion of HMF polarity (corresponding to the inversion of solar magnetic field) consists of three periods: 1) appearance beside the global (that is connecting all heliolongitudes) heliospheric current sheet (HCS) corresponding to the old polarity of one or more nonglobal HCSs (the first transition period); then 2) the disappearance of the above global HCS (the inversion proper); and then 3) the appearance of the global HCS corresponding to new polarity even with one or more nonglobal HCSs (the second transition period). Using the WSO data on magnetic field on the HMF source surface as the model of the HMF polarity distribution we calculated it for each Carrington rotation in 1976-2014. The procedure was also suggested how to use the known HMF polarity distribution for the GCR intensity modeling during the process of the inversion of HMF polarity. So in this talk, first, we are looking for the GCR-effects specific for this phase in SC 24 - the Gnevyshev peak between two gaps; the energy hysteresis; and probably some effects connected with the inversion of the high latitude solar magnetic field - and compare them with the GCR behavior during the maximum phases of previous solar cycles. Second, we calculate the GCR intensity in the heliosphere during four periods of the inversion of the HMF polarity and compare it with the observations. The development of the sunspot activity and the GCR intensity in the current solar cycle is also briefly discussed.

Krainev, Mikhail; Kalinin, Mikhail

27

Azimuthal and meridional asymmetries of the solar wind and quasiperiodic variations of intensity of Galactic Cosmic Rays (GCR)  

NASA Astrophysics Data System (ADS)

The results of analysis of 27 day, annual and quasi-two year variation of galactic cosmic rays (GCR) are presented. The dependence of the periods of 27 day GCR variation on the energy of initial radiation is discovered, according to the data during 1980 of the World network of station in sufficiently wide range of the observed threshold energy. The dependence of the annual variation of GCR is established, according to the data of the Huancayo station in conforming with the change of the polarity of the General Magnetic Field of the Sun (GMFS).

Shatashvili, L. K.; Djapiashvili, T. V.; Kavlashvili, B. G.; Naskidashvili, B. D.; Rogava, O. G.; Shafer, G. V.

1985-08-01

28

Centennial modulation of GCR flux as deduced by Ti-44 in chondrites  

NASA Astrophysics Data System (ADS)

We present here the results obtained by the measurement of 20 chondrites fell in the last 3 centuries. The activity of Ti-44, measured by a HPGe+NaI spectrometer housed in the Monte dei Cappuccini Laboratory in Torino, clearly shows a centennial periodicity in the GCR flux superposed to a decreasing trend. The Ti-44 activity is related to GCR intensity and its modulation is due to heliospheric magnetic field in the interplanetary space between 1 and 2.5 AU. The results are consistent in phase and magnitude with the variations in solar open magnetic field intensity estimated by Solanki et al. (2000) and with the Gleissberg cycle of the sunspot number series.

Cini Castagnoli, G.; Taricco, C.; Bhandari, N.; Verma, N.

29

Badhwar-O'Neil 2007 Galactic Cosmic Ray (GCR) Model Using Advanced Composition Explorer (ACE) Measurements for Solar Cycle 23  

NASA Technical Reports Server (NTRS)

Advanced Composition Explorer (ACE) satellite measurements of the galactic cosmic ray flux and correlation with the Climax Neutron Monitor count over Solar Cycle 23 are used to update the Badhwar O'Neill Galactic Cosmic Ray (GCR) model.

ONeill, P. M.

2007-01-01

30

GCR3 encodes an acidic protein that is required for expression of glycolytic genes in Saccharomyces cerevisiae.  

PubMed Central

Screening of a mutagenized strain carrying a multicopy ENO1-'lacZ fusion plasmid revealed a new mutation affecting several glycolytic enzyme activities. The recessive single nuclear gene mutation, named gcr3, caused an extremely defective growth phenotype on fermentable carbon sources such as glucose, while growth on respiratory media was almost normal. The GCR3 gene was obtained by growth complementation from a genomic DNA library, and the complemented strains had normal enzyme levels. GCR3 gene was sequenced, and a 99,537-Da protein was predicted. The predicted GCR3 protein was fairly acidic (net charge, -34). The C-terminal region was highly charged, and an acidic stretch was found in it. Images PMID:1512188

Uemura, H; Jigami, Y

1992-01-01

31

Integrated network construction using event based text mining  

E-print Network

Integrated network construction using event based text mining Yvan Saeys, Sofie Van Landeghem numerous interactions between biological entities. Text mining techniques have been increasingly useful mining in the systems biology field has been restricted mostly to the discovery of protein

Gent, Universiteit

32

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

33

On the mechanisms forming the GCR intensity distribution in the heliosphere  

NASA Astrophysics Data System (ADS)

Recently we draw a conclusion based on solving the boundary-value problem for the galactic cosmic ray (GCR) intensity that during the periods of low and intermediate solar activity the contribution to the GCR intensity of the particle drift in the heliospheric magnetic fields (HMF) is much higher than usually believed. This contribution increases as the cosmic ray energy (T) and the heliocentric distance (r) decrease and for the low energy protons (T ? 100 MeV) near the Earth around solar minima it comes to ? 70% of the total calculated intensity for both HMF polarities. Here we try to reveal and illustrate the physical mechanisms responsible for this effect using the simple model. Note that in this talk we restrict our consideration only to discussion of the mechanisms forming J(r, ?, T) for any moment characterized by some fixed set of the main parameters (the HMF strength, the solar wind velocity, the current sheet tilt, the HMF polarity etc.). How the relative role of different physical processes changes when this main set is changing with time (t) and the calculated GCR intensity J(r, ?, T; t) describes both the sunspot and magnetic cycles is outside of the scope of the talk.

Krainev, Mikhail

34

Understanding the Growth Phenotype of the Yeast gcr1 Mutant in Terms of Global Genomic Expression Patterns  

Microsoft Academic Search

The phenotype of an organism is the manifestation of its expressed genome. The gcr1 mutant of yeast grows at near wild-type rates on nonfermentable carbon sources but exhibits a severe growth defect when grown in the presence of glucose, even when nonfermentable carbon sources are available. Using DNA microarrays, the genomic expression patterns of wild-type and gcr1 mutant yeast growing

M. CECILIA LOPEZ; HENRY V. BAKER

2000-01-01

35

Event-Based Learning: Educational and Technological Perspectives  

Microsoft Academic Search

Teachers have traditionally introduced current events in the classroom to leverage news topics relevant to the curriculum; however, to my knowledge no studies have attempted to provide a comprehensive research view on these event-related teaching activities. This paper presents an introductory event-based learning analysis from educational and technological research perspectives. This research effort provides a broad characterization of event-based learning

Sebastian de la Chica

36

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

37

Understanding the Growth Phenotype of the Yeast gcr1 Mutant in Terms of Global Genomic Expression Patterns  

PubMed Central

The phenotype of an organism is the manifestation of its expressed genome. The gcr1 mutant of yeast grows at near wild-type rates on nonfermentable carbon sources but exhibits a severe growth defect when grown in the presence of glucose, even when nonfermentable carbon sources are available. Using DNA microarrays, the genomic expression patterns of wild-type and gcr1 mutant yeast growing on various media, with and without glucose, were compared. A total of 53 open reading frames (ORFs) were identified as GCR1 dependent based on the criterion that their expression was reduced twofold or greater in mutant versus wild-type cultures grown in permissive medium consisting of YP supplemented with glycerol and lactate. The GCR1-dependent genes, so defined, fell into three classes: (i) glycolytic enzyme genes, (ii) ORFs carried by Ty elements, and (iii) genes not previously known to be GCR1 dependent. In wild-type cultures, GCR1-dependent genes accounted for 27% of the total hybridization signal, whereas in mutant cultures, they accounted for 6% of the total. Glucose addition to the growth medium resulted in a reprogramming of gene expression in both wild-type and mutant yeasts. In both strains, glycolytic enzyme gene expression was induced by the addition of glucose, although the expression of these genes was still impaired in the mutant compared to the wild type. By contrast, glucose resulted in a strong induction of Ty-borne genes in the mutant background but did not greatly affect their already high expression in the wild-type background. Both strains responded to glucose by repressing the expression of genes involved in respiration and the metabolism of alternative carbon sources. Thus, the severe growth inhibition observed in gcr1 mutants in the presence of glucose is the result of normal signal transduction pathways and glucose repression mechanisms operating without sufficient glycolytic enzyme gene expression to support growth via glycolysis alone. PMID:10940042

López, M. Cecilia; Baker, Henry V.

2000-01-01

38

The GCR1 gene encodes a positive transcriptional regulator of the enolase and glyceraldehyde-3-phosphate dehydrogenase gene families in Saccharomyces cerevisiae.  

PubMed Central

The intracellular concentrations of the polypeptides encoded by the two enolase (ENO1 and ENO2) and three glyceraldehyde-3-phosphate dehydrogenase (TDH1, TDH2, and TDH3) genes were coordinately reduced more than 20-fold in a Saccharomyces cerevisiae strain carrying the gcr1-1 mutation. The steady-state concentration of glyceraldehyde-3-phosphate dehydrogenase mRNA was shown to be approximately 50-fold reduced in the mutant strain. Overexpression of enolase and glyceraldehyde-3-phosphate dehydrogenase in strains carrying multiple copies of either ENO1 or TDH3 was reduced more than 50-fold in strains carrying the gcr1-1 mutation. These results demonstrated that the GCR1 gene encodes a trans-acting factor which is required for efficient and coordinate expression of these glycolytic gene families. The GCR1 gene and the gcr1-1 mutant allele were cloned and sequenced. GCR1 encodes a predicted 844-amino-acid polypeptide; the gcr1-1 allele contains a 1-base-pair insertion mutation at codon 304. A null mutant carrying a deletion of 90% of the GCR1 coding sequence and a URA3 gene insertion was constructed by gene replacement. The phenotype of a strain carrying this null mutation was identical to that of the gcr1-1 mutant strain. Images PMID:3547083

Holland, M J; Yokoi, T; Holland, J P; Myambo, K; Innis, M A

1987-01-01

39

Glycolytic gene expression in Saccharomyces cerevisiae: nucleotide sequence of GCR1, null mutants, and evidence for expression.  

PubMed Central

In Saccharomyces cerevisiae, the gcr mutation is known to have a profound effect on the levels of most glycolytic enzymes, reducing them to 5% of normal or less in growth on noncarbohydrates. Here I report the preparation of chromosomal gcr insertion and deletion mutations. The null mutations were recessive, were not lethal, and caused a pattern of glycolytic enzyme deficiency similar to that seen earlier for the gcr1-1 allele, including the partial inducibility by glucose of the residual enzyme activities. DNA sequence analysis showed that GCR1 encoded a protein of molecular weight 94,414, with a very low codon bias index, characteristic of several S. cerevisiae regulatory genes; adjacent 5' and 3' sequences contained elements suggesting that it was transcribed, polyadenylated, and translated. RNA gel transfer hybridization experiments with purified polyadenylated RNA and a probe complementary to the 5' portion of the open reading frame showed that Ger was expressed as a polyadenylated transcript. Together with previous work, the present results suggest that the Gcr product may be a transcriptional factor necessary specifically for the high-level transcription of a limited set of genes whose products, the enzymes of glycolysis, constitute a substantial fraction of cell proteins and are responsible for the primary metabolic flux in many cells. Images PMID:3025612

Baker, H V

1986-01-01

40

A Qualitative Event-based Approach to Continuous Systems Diagnosis  

E-print Network

1 A Qualitative Event-based Approach to Continuous Systems Diagnosis Matthew J. Daigle Member, IEEE, Xenofon D. Koutsoukos Senior Member, IEEE, and Gautam Biswas Senior Member, IEEE Abstract--Fault diagnosis-event diagnosis methods are used extensively, they do not easily address parametric fault isolation in systems

Daigle, Matthew

41

Distributed Virtual Environments and VRML: An Event-Based Architecture  

Microsoft Academic Search

We present an approach to the problem of implementing and supporting Distributed Virtual Environments (DVEs) on the Internet using an event-based notification system. The three most important characteristics of this approach are generality, scalability, and openness. We describe the notification system, how we use it to provide general DVE support, its use in implementing the Living Worlds Virtual Reality Modeling

Mike Wray; Rycharde Hawkes

1998-01-01

42

Simulation of Quantum Computation: A deterministic event-based approach  

E-print Network

We demonstrate that locally connected networks of machines that have primitive learning capabilities can be used to perform a deterministic, event-based simulation of quantum computation. We present simulation results for basic quantum operations such as the Hadamard and the controlled-NOT gate, and for seven-qubit quantum networks that implement Shor's numbering factoring algorithm.

K. Michielsen; K. De Raedt; H. De Raedt

2005-01-24

43

CENDA: Camouflage Event Based Malicious Node Detection Architecture  

E-print Network

CENDA: Camouflage Event Based Malicious Node Detection Architecture Kanthakumar Pongaliur Li Xiao Based Malicious Node Detection Architecture (CENDA) is a proactive architecture that uses camouflage events generated by mobile-nodes to detect malicious nodes while identifying the type of attack. We

Liu, Alex X.

44

Elemental GCR Observations during the 2009-2010 Solar Minimum Period  

NASA Technical Reports Server (NTRS)

Using observations from the Cosmic Ray Isotope Spectrometer (CRIS) onboard the Advanced Composition Explorer (ACE), we present new measurements of the galactic cosmic ray (GCR) elemental composition and energy spectra for the species B through Ni in the energy range approx. 50-550 MeV/nucleon during the record setting 2009-2010 solar minimum period. These data are compared with our observations from the 1997-1998 solar minimum period, when solar modulation in the heliosphere was somewhat higher. For these species, we find that the intensities during the 2009-2010 solar minimum were approx. 20% higher than those in the previous solar minimum, and in fact were the highest GCR intensities recorded during the space age. Relative abundances for these species during the two solar minimum periods differed by small but statistically significant amounts, which are attributed to the combination of spectral shape differences between primary and secondary GCRs in the interstellar medium and differences between the levels of solar modulation in the two solar minima. We also present the secondary-to-primary ratios B/C and (Sc+Ti+V)/Fe for both solar minimum periods, and demonstrate that these ratios are reasonably well fit by a simple "leaky-box" galactic transport model that is combined with a spherically symmetric solar modulation model.

Lave, K. A.; Israel, M. H.; Binns, W. R.; Christian, E. R.; Cummings, A. C.; Davis, A. J.; deNolfo, G. A.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; vonRosenvinge, T. T.; Wiedenbeck, M. E.

2013-01-01

45

GCR-induced Photon Luminescence of the Moon: The Moon as a CR Detector  

NASA Astrophysics Data System (ADS)

We report on the results of a preliminary study of the GCR-induced photon luminescence of the Moon using the Monte Carlo program FLUKA. The model of the lunar surface is taken to be the chemical composition of soils found at various landing sites during the Apollo and Luna programs, averaged over all such sites to define a generic regolith for the present analysis. This then becomes the target that is bombarded by Galactic Cosmic Rays (GCRs) in FLUKA to determine the photon fluence when there is no sunshine or Earthshine. From the photon fluence we derive the energy spectrum which can be utilized to design an orbiting optical instrument for measuring the GCR-induced luminescence. This is to be distinguished from the gamma-ray spectrum produced by the radioactive decay of its radiogenic constituents lying in the surface and interior. Also, we investigate transient optical flashes from high-energy CRs impacting the lunar surface (boulders and regolith). The goal is to determine to what extent the Moon could be used as a rudimentary CR detector. Meteor impacts on the Moon have been observed for centuries to generate such flashes, so why not CRs?

Wilson, Thomas; Lee, Kerry

46

27-DAY Variations of the GCR Intensity and Anisotropy in Different Epochs of Solar Magnetic Activity  

NASA Astrophysics Data System (ADS)

We study 27-day (27d) variations of the galactic cosmic ray (GCR) intensity (I) and the ecliptic anisotropy (A) based on analyses of neutron monitors and ground muon telescopes data for different epochs of solar magnetic activity. Generally, there can be distinguish three scenarios: (1) when the 27d variations are revealed in changes of the both, I and A; (2) 27d variation is observed in changes of I, but not in A; and (3) 27d variation is observed in changes of A, but not in I. We suppose that these phenomena are related with the distinguished mechanisms of creation of the 27d variations in changes of I and A. Among them more decipherable should be: (1) a distinction in sizes of vicinity of heliosphere where 27d variations of I and A are created, (2) propagation of the processes of heliolongitudinal asymmetry (corotating interaction regions) from the Sun to inner and to further distances of heliosphere, (3) preferential roles of spiral interplanetary magnetic field (IMF) in changes of A. Especially, it is inestimable in minimum and near minimum epochs of solar activity, when, even under absence of any heliolongitudinal asymmetries in parameters of solar wind and solar activity a recognizable 27d variation in A is observed due to drift of GCR particles in well established sector structure of the IMF. For all three scenarios we have recognized several distinctions in the rigidity dependences of the amplitudes of the (27d) variations of the I and A.

Alania, Michael; Modzelewska, Renata; Gil, Agnieszka; Wawrzynczak-Szaban, Anna

47

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

48

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

49

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

50

Event-based prospective memory performance in autism spectrum disorder  

Microsoft Academic Search

The purpose of the present study was to investigate event-based prospective memory performance in individuals with autism\\u000a spectrum disorder and to explore possible relations between laboratory-based prospective memory performance and everyday performance.\\u000a Nineteen children and adolescents with autism spectrum disorder and 19 matched neurotypical controls participated. The laboratory-based\\u000a prospective memory test was embedded in a visuo-spatial working memory test and

Mareike Altgassen; Maren Schmitz-Hübsch; Matthias Kliegel

2010-01-01

51

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

52

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

53

Secondary Cosmic Ray particles due to GCR interactions in the Earth's atmosphere  

E-print Network

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.

G. Battistoni; F. Cerutti; A. Fassò; A. Ferrari; M. V. Garzelli; M. Lantz; S. Muraro; L. S. Pinsky; J. Ranft; S. Roesler; P. R. Sala

2007-11-13

54

Event-based simulation of quantum physics experiments  

E-print Network

We review an event-based simulation approach which reproduces the statistical distributions of wave theory not by requiring the knowledge of the solution of the wave equation of the whole system but by generating detection events one-by-one according to an unknown distribution. We illustrate its applicability to various single photon and single neutron interferometry experiments and to two Bell test experiments, a single-photon Einstein-Podolsky-Rosen experiment employing post-selection for photon pair identification and a single-neutron Bell test interferometry experiment with nearly $100\\%$ detection efficiency.

Kristel Michielsen; Hans De Raedt

2013-12-25

55

Area method analysis and thermodynamic behavior of nonmetallic micro-inclusions in casting slab of GCr15 bearing steel  

Microsoft Academic Search

The distribution and characteristics of nonmetallic micro-inclusions of GCr15 bearing steel were explored through metallographic\\u000a area method in virtue of tracer method and electronic microscope. The results show that the micro-inclusions, of which the\\u000a average value is 0.032%, are mainly the compounds formed via the adsorption\\/aggregation of multielement deoxidized compounds\\u000a and secondarily deoxidized products on tundish liquid level. The micro-inclusions

Hongli Wang; Yitai Ma; Shuoming Wang

2009-01-01

56

Event-Based 64-Channel Binaural Silicon Cochlea with Q Enhancement Mechanisms  

E-print Network

Event-Based 64-Channel Binaural Silicon Cochlea with Q Enhancement Mechanisms Shih-Chii Liu1 College of Engineering Abstract-- This paper describes an event-based binaural silicon cochlea aimed by rectification and asynchronous output quantization in the timing domain. A binaural event-based silicon cochlea

Liu, Shih-Chii

57

The expression of PHO92 is regulated by Gcr1, and Pho92 is involved in glucose metabolism in Saccharomyces cerevisiae.  

PubMed

Ydr374c (Pho92) contains a YTH domain in its C-terminal region and is a human YTHDF2 homologue. Previously, we reported that Pho92 regulates phosphate metabolism by regulating PHO4 mRNA stability. In this study, we found that growth of the ?pho92 strain on SG media was slower than that of the wild type and that PHO92 expression was up-regulated by non-fermentable carbon sources, such as ethanol and glycerol, but not by fermentable carbon sources. Furthermore, two conserved Gcr1-binding regions were identified in the upstream, untranslated region of PHO92. Gcr1 is an important factor involved in the coordinated regulation of glycolytic gene expression. Mutation of two Gcr1-binding sites of the PHO92 upstream region resulted in a growth defect on SD media. Finally, mutagenesis of the Gcr1-binding sites of the PHO92 upstream region and deletion of GCR1 resulted in up-regulation of PHO92, and this resulted from inhibition of PHO4 mRNA degradation. Based on these results, we suggest that Gcr1 regulates the expression of PHO92, and Pho92 is involved in glucose metabolism. PMID:24850134

Kang, Hyun-Jun; Chang, Miwha; Kang, Chang-Min; Park, Yong-Sung; Yoon, Bong-June; Kim, Tae-Hyoung; Yun, Cheol-Won

2014-11-01

58

Event-based user classification in Weibo media.  

PubMed

Weibo media, known as the real-time microblogging services, has attracted massive attention and support from social network users. Weibo platform offers an opportunity for people to access information and changes the way people acquire and disseminate information significantly. Meanwhile, it enables people to respond to the social events in a more convenient way. Much of the information in Weibo media is related to some events. Users who post different contents, and exert different behavior or attitude may lead to different contribution to the specific event. Therefore, classifying the large amount of uncategorized social circles generated in Weibo media automatically from the perspective of events has been a promising task. Under this circumstance, in order to effectively organize and manage the huge amounts of users, thereby further managing their contents, we address the task of user classification in a more granular, event-based approach in this paper. By analyzing real data collected from Sina Weibo, we investigate the Weibo properties and utilize both content information and social network information to classify the numerous users into four primary groups: celebrities, organizations/media accounts, grassroots stars, and ordinary individuals. The experiments results show that our method identifies the user categories accurately. PMID:25133235

Guo, Liang; Wang, Wendong; Cheng, Shiduan; Que, Xirong

2014-01-01

59

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

60

Oil Spill! An Event-Based Science Module. Student Edition. Oceanography 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.

61

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.

62

First Flight!: An Event-Based Science Module. Student Edition. Physics 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

First Flight!: An Event-Based Science Module Teacher's Guide. Physics Module.  

ERIC Educational Resources Information Center

This book is designed for middle school life 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.

64

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

Microsoft Academic Search

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 in the prospective component (remembering that you have to do something)

Rebekah E. Smith; Ute J. Bayen

2006-01-01

65

Gold Rush!: An Event-Based Science Module. Teacher's Guide. Geology 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.

66

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.

67

Hurricane!: An Event-Based Science Module. Teacher's Guide. Meteorology Module.  

ERIC Educational Resources Information Center

This book is designed for middle school earth science teachers to help their students learn about problems with hurricanes and 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,…

Wright, Russell G.

68

Outbreak!: An Event-Based Science Module. Teacher's Guide. Disease and Immunity Module.  

ERIC Educational Resources Information Center

This book is designed for middle school life 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.

69

Survive? An Event-Based Science Module. Teacher's Guide. Animals and Adaptation Module.  

ERIC Educational Resources Information Center

This book is designed for middle school earth 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, independent research,…

Wright, Russell G.

70

Toxic Leak!: An Event-Based Science Module. Teacher's Guide. Groundwater Module.  

ERIC Educational Resources Information Center

This book is designed for middle school earth science teachers to help their students learn about problems with toxic leaking and 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…

Wright, Russell G.

71

Flood!: An Event-Based Science Module. Teacher's Guide. Stream Dynamics Module.  

ERIC Educational Resources Information Center

This book is designed for middle school earth science teachers to help their students learn about problems with floods and 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,…

Wright, Russell G.

72

Thrill Ride! An Event-Based Science Module. Teacher's Guide. Force and Motion Module.  

ERIC Educational Resources Information Center

This book is designed for middle school life 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.

73

Blight! An Event-Based Science Module. Teacher's Guide. Plants and Plant Diseases Module.  

ERIC Educational Resources Information Center

This book is designed for middle school life 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.

74

Fraud! An Event-Based Science Module. Teacher's Guide. Chemistry Module.  

ERIC Educational Resources Information Center

This book is designed for middle school life 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.

75

Gold Medal!: An Event-Based Science Module. Teacher's Guide. Physiology Module.  

ERIC Educational Resources Information Center

This book is designed for middle school life 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.

76

Fire!: An Event-Based Science Module. Student Edition. Chemistry and Fire Ecology 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.

77

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.

78

University of Oregon | Public and Government Affairs | 541-346-5020 | gcr@uoregon.edu |11/15/12 | p.1 Collaborations  

E-print Network

University of Oregon | Public and Government Affairs | 541-346-5020 | gcr@uoregon.edu |11/15/12 | p-institutional partnerships and shared services can offer benefits and savings. In addition to its participation with other with IRS arbitrage and private use regulations and file related reports. Until existing XI-G and XI-F bonds

Oregon, University of

79

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

80

Assessing the continuum of event-based biosurveillance through an operational lens.  

PubMed

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 a significant impact on the One Health landscape. How the attributes identified in 2001 relate to the new range of event-based biosurveillance technologies is unclear. This article frames the continuum of event-based biosurveillance systems (that fuse media reports from the internet), models (ie, computational that forecast disease occurrence), and constructs (ie, descriptive analytical reports) through an operational lens (ie, aspects and attributes associated with operational considerations in the development, testing, and validation of the event-based biosurveillance methods and models and their use in an operational environment). A workshop was held in 2010 to scientifically identify, develop, and vet a set of attributes for event-based biosurveillance. Subject matter experts were invited from 7 federal government agencies and 6 different academic institutions pursuing research in biosurveillance event detection. We describe 8 attribute families for the characterization of event-based biosurveillance: event, readiness, operational aspects, geographic coverage, population coverage, input data, output, and cost. Ultimately, the analyses provide a framework from which the broad scope, complexity, and relevant issues germane to event-based biosurveillance useful in an operational environment can be characterized. PMID:22320664

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

2012-03-01

81

Deriving tabular event-based specifications from goal-oriented requirements models  

Microsoft Academic Search

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

Renaud De Landtsheer; Emmanuel Letier

2004-01-01

82

Department of Computing Combining event-based and state-based  

E-print Network

with the formal modelling of sig- nalling and point control in the domain of railway engineering. Rules-based and state-based modeling for railway verification Faron Moller Hoang Nga Nguyen Markus Roggenbach Steve Schneider Helen Treharne March 19th 2012 #12;Combining event-based and state-based modelling for railway

Doran, Simon J.

83

Event-based Particle Filtering for Robot Self-Localization David Weikersdorfer and Jorg Conradt  

E-print Network

Abstract-- We propose a novel algorithm for robot self- localization using an event-based sensor. An event hardware for robotic devices. We evaluate our algorithm in a simulation environment and with experimental@tum.de Fig. 1: The embedded DVS board (left) and a typical sensor recording displayed by integrating events

Kuehnlenz, Kolja

84

Event-based Estimation of User Experience for Network Video Streaming  

E-print Network

Event-based Estimation of User Experience for Network Video Streaming Yongfeng Huang, Jin Xiao services, it is important to understand how network performance affects user experience. The model's Quality of Experience (QoE), it is important to have a good understanding of the different parameters

Boutaba, Raouf

85

Optimization of Correlated Source Coding for Event-Based Monitoring in Sensor Networks  

E-print Network

transmissions for the important parts. For instance, consider a set of acoustic sensors deployed in a forestOptimization of Correlated Source Coding for Event-Based Monitoring in Sensor Networks Jaspreet the inherent bandwidth and energy constraints associated with wireless sensor networks, we consider the problem

California at Santa Barbara, University of

86

A MODULAR EVENT-BASED ARCHITECTURE FOR WORKFLOW SYSTEMS Mehran Najafi and Kamran Sartipi  

E-print Network

; Flexible Workflow; Event-based Architecture; Modular Architecture; Intelligent Workflow. 1. Introduction. Workflow systems need mechanisms to make them flexible and deal with those deviations. In a small system and flexibility in workflow systems are the main objectives. We address reusability by introducing modules

Sartipi, Kamran

87

Reconstruction of a flux transfer event based on observations from five THEMIS satellites  

E-print Network

Reconstruction of a flux transfer event based on observations from five THEMIS satellites A. T. Y a flux transfer event (FTE) observed by Time History of Events and Macroscale Interactions during transfer event (FTE) near the dusk magnetopause on 20 May 2007. During this interval, one THEMIS satellite

California at Berkeley, University of

88

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

E-print Network

that graphical user interfaces (GUIs) highly affect--positive or negative--the quality and reliability of human used for testing it also affect the factors mentioned above, especially failure data to be observedEvent-Based GUI Testing and Reliability Assessment Techniques An Experimental Insight

Memon, Atif M.

89

A Differential Deficit in Time Versus Event-Based Prospective Memory in Parkinson's Disease  

Microsoft Academic Search

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

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

2011-01-01

90

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. PMID:19402953

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

2009-01-01

91

An Energy Efficient Layer for Event-Based Communications in Web-of-Things Frameworks  

E-print Network

to the concept of Internet-of-Things (IoT) [1]. This idiom includes the concept of Wireless Sensor Networks (WSN the energy consumption of things connected to the Internet through Wi-Fi. We rely on the Web-of-ThingsAn Energy Efficient Layer for Event-Based Communications in Web-of-Things Frameworks Gérôme Bovet1

Boyer, Edmond

92

Event-Based Prospective Memory in Children with Sickle Cell Disease: Effect of Cue Distinctiveness  

Microsoft Academic Search

Event-based prospective memory (EB-PM) is the formation of an intention and remembering to perform it in response to a specific event. Currently, EB-PM performance in children with sickle cell disease (SCD) is unknown. In this study, we designed a computer-based task of EB-PM; No-Stroke, Silent-Infarct, and Overt-Stroke groups performed significantly below the demographically similar control group without SCD. Cue distinctiveness

Stephen R. McCauley; Claudia Pedroza

2010-01-01

93

The GCR All-Particle Spectrum in the 0.1-100 TeV Energy Range  

NASA Astrophysics Data System (ADS)

The results of direct measurements of the all particle spectra by five different instruments on satellites and balloons are considered. It is shown, that is the representatio as the flux multiplied by energy to the power of 2.6 the all-particle spectrum shows a 'step'. The parameters of this 'step' and its origin are analyzed. Historically it has so happ ened that the all-particle spectrum obtained as the sum individual components, the energy range 1 < E < (5 - 10) TeV in the proton spectrum is not covered by direct measurements. Usually this energy interval in the all-particle spectrum is filled via interp olation, which is bases on the assumption that the proton spectrum is similar to the spectrum of nuclei. This spectrum is usually considered to be the all-particle GCR spectrum Io (E ) [1]. Direct information on the all-particle spectrum in the energy range from 1 to 10 TeV can be obtained using direct measurements of the of the all-particle spectrum by electronic instruments. For the first time such information was obtained in 1972 as a result of the all-particle spectrum measurements by the SEZ-14 instrument on the 'Proton1,2,3' satellites and the SEZ-15 instrument on the 'Proton-4' satellite [2,3]. These measurements revealed an anomaly in the all-particle spectrum in the 1-10 TeV energy range. In 1997 the spectrum was measured again by the TIC instrument [4]. The TIC instrument measured the energy release of all-particles arriving from arbitrary directions. As it was shown by the authors in [4,5] the energy release spectrum revealed the same anomaly in the all-particle spectrum, previously observed in the measurements made on 'Proton' satellites [2]. The results of the measurements made by the TIC, SEZ-14 and SEZ-15 are shown in Fig.1. The solid line in Fig.1 shows the function ?(E ), which gives a good approximation of the experimental all-particle spectrum at a =0.4 TeV. ?(E ) = E 2.6 Io (E ) (E /a)3 0.11 } + 0.130m-2s-1 sr -1 T eV 1.6 (1) {1 + 0.37 = [1 + (E /a)3 ]0.2 1 + (E /a)3 It can be seen from Fig.1 that the anomaly in the all-particle spectrum shows a

Tolstaya, Ekaterina D.; Grigorov, N. L.

2003-07-01

94

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

95

Fast vision through frameless event-based sensing and convolutional processing: application to texture recognition.  

PubMed

Address-event representation (AER) is an emergent hardware technology which shows a high potential for providing in the near future a solid technological substrate for emulating brain-like processing structures. When used for vision, AER sensors and processors are not restricted to capturing and processing still image frames, as in commercial frame-based video technology, but sense and process visual information in a pixel-level event-based frameless manner. As a result, vision processing is practically simultaneous to vision sensing, since there is no need to wait for sensing full frames. Also, only meaningful information is sensed, communicated, and processed. Of special interest for brain-like vision processing are some already reported AER convolutional chips, which have revealed a very high computational throughput as well as the possibility of assembling large convolutional neural networks in a modular fashion. It is expected that in a near future we may witness the appearance of large scale convolutional neural networks with hundreds or thousands of individual modules. In the meantime, some research is needed to investigate how to assemble and configure such large scale convolutional networks for specific applications. In this paper, we analyze AER spiking convolutional neural networks for texture recognition hardware applications. Based on the performance figures of already available individual AER convolution chips, we emulate large scale networks using a custom made event-based behavioral simulator. We have developed a new event-based processing architecture that emulates with AER hardware Manjunath's frame-based feature recognition software algorithm, and have analyzed its performance using our behavioral simulator. Recognition rate performance is not degraded. However, regarding speed, we show that recognition can be achieved before an equivalent frame is fully sensed and transmitted. PMID:20181543

Perez-Carrasco, Jose Antonio; Acha, Begona; Serrano, Carmen; Camunas-Mesa, Luis; Serrano-Gotarredona, Teresa; Linares-Barranco, Bernabe

2010-04-01

96

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

E-print Network

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.

Kristel Michielsen; Hans De Raedt

2014-03-18

97

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

98

A Markovian event-based framework for stochastic spiking neural networks.  

PubMed

In spiking neural networks, the information is conveyed by the spike times, that depend on the intrinsic dynamics of each neuron, the input they receive and on the connections between neurons. In this article we study the Markovian nature of the sequence of spike times in stochastic neural networks, and in particular the ability to deduce from a spike train the next spike time, and therefore produce a description of the network activity only based on the spike times regardless of the membrane potential process. To study this question in a rigorous manner, we introduce and study an event-based description of networks of noisy integrate-and-fire neurons, i.e. that is based on the computation of the spike times. We show that the firing times of the neurons in the networks constitute a Markov chain, whose transition probability is related to the probability distribution of the interspike interval of the neurons in the network. In the cases where the Markovian model can be developed, the transition probability is explicitly derived in such classical cases of neural networks as the linear integrate-and-fire neuron models with excitatory and inhibitory interactions, for different types of synapses, possibly featuring noisy synaptic integration, transmission delays and absolute and relative refractory period. This covers most of the cases that have been investigated in the event-based description of spiking deterministic neural networks. PMID:21499739

Touboul, Jonathan D; Faugeras, Olivier D

2011-11-01

99

A scheme for PET data normalization in event-based motion correction  

NASA Astrophysics Data System (ADS)

Line of response (LOR) rebinning is an event-based motion-correction technique for positron emission tomography (PET) imaging that has been shown to compensate effectively for rigid motion. It involves the spatial transformation of LORs to compensate for motion during the scan, as measured by a motion tracking system. Each motion-corrected event is then recorded in the sinogram bin corresponding to the transformed LOR. It has been shown previously that the corrected event must be normalized using a normalization factor derived from the original LOR, that is, based on the pair of detectors involved in the original coincidence event. In general, due to data compression strategies (mashing), sinogram bins record events detected on multiple LORs. The number of LORs associated with a sinogram bin determines the relative contribution of each LOR. This paper provides a thorough treatment of event-based normalization during motion correction of PET data using LOR rebinning. We demonstrate theoretically and experimentally that normalization of the corrected event during LOR rebinning should account for the number of LORs contributing to the sinogram bin into which the motion-corrected event is binned. Failure to account for this factor may cause artifactual slice-to-slice count variations in the transverse slices and visible horizontal stripe artifacts in the coronal and sagittal slices of the reconstructed images. The theory and implementation of normalization in conjunction with the LOR rebinning technique is described in detail, and experimental verification of the proposed normalization method in phantom studies is presented.

Zhou, Victor W.; Kyme, Andre Z.; Meikle, Steven R.; Fulton, Roger

2009-09-01

100

Event-based knowledge extraction from free-text descriptions for art images by using semantic role labeling approaches  

Microsoft Academic Search

Purpose – The purpose of this paper is to show how previous studies have demonstrated that non-professional users prefer using event-based conceptual descriptions, such as “a woman wearing a hat”, to describe and search images. In many art image archives, these conceptual descriptions are manually annotated in free-text fields. This study aims to explore technologies to automate event-based knowledge extractions

Chia-hung Lin; Chia-wei Yen; Jen-shin Hong; Samuel Cruz-lara

2008-01-01

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. PMID:22399975

Sánchez, José; Guarnes, Miguel Ángel; Dormido, Sebastián

2009-01-01

102

Event-Based Study of the Effect of Execution Environments on Parallel Program Performance  

NASA Technical Reports Server (NTRS)

In this paper we seek to demonstrate the importance of studying the effect of changes in execution environment parameters, on parallel applications executed on state-of-the-art multiprocessors. A comprehensive methodology for event-based analysis of program behavior is introduced. This methodology is used to study the performance significance of various system parameters such as processor speed, message-buffer size, buffer copy speed, network bandwidth, communication latency, interrupt overheads and other system parameters. With the help cf a few CFD examples, we illustrate the use of our technique in determining suitable parameter values of the execution environment for three applications. We also demonstrate how this approach can be used to predict performance across architectures and illustrate the use of visual and profile-like feedback to expose the effect of system parameters changes on the performance of specific applications module.

Sarukkai, Sekhar R.; Yan, Jerry C.; Craw, James (Technical Monitor)

1995-01-01

103

US/FRG umbrella agreement for cooperation in GCR development. Fuel, fission products, and graphite subprogram. Quarterly status report, January 1, 1983-March 31, 1983  

SciTech Connect

This report describes the status of the cooperative work being performed in the Fuel, Fission Product, and Graphite Subprogram under the HTR-Implementing Agreement of the United States/Federal Republic of Germany Umbrella Agreement for Cooperation in GCR Development. The status is described relative to the commitments in the Subprogram Plan for Fuel, Fission Products, and Graphite, Revision 5, April 1982, and Revision 6, February 1983. The work described was performed during the period January 1 through March 31, 1983 in the HTGR Base Technology Program at Oak Ridge National Laboratory, the HTGR Fuel and Plant Technology Programs at GA Technologies Inc. (GA), and the Project HTR-Brennstoffkreislauf of the Entwicklungsgemeinschaft HTR at KFA Juelich, HRB Mannheim, INTERATOM Bensberg, HOBEG Hanau, and SIGRI Meitingen.

Turner, R.F.

1983-04-01

104

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

105

Too exhausted to remember: ego depletion undermines subsequent event-based prospective memory.  

PubMed

Past research has consistently found that people are likely to do worse on high-level cognitive tasks after exerting self-control on previous actions. However, little has been unraveled about to what extent ego depletion affects subsequent prospective memory. Drawing upon the self-control strength model and the relationship between self-control resources and executive control, this study proposes that the initial actions of self-control may undermine subsequent event-based prospective memory (EBPM). Ego depletion was manipulated through watching a video requiring visual attention (Experiment 1) or completing an incongruent Stroop task (Experiment 2). Participants were then tested on EBPM embedded in an ongoing task. As predicted, the results showed that after ruling out possible intervening variables (e.g. mood, focal and nonfocal cues, and characteristics of ongoing task and ego depletion task), participants in the high-depletion condition performed significantly worse on EBPM than those in the low-depletion condition. The results suggested that the effect of ego depletion on EBPM was mainly due to an impaired prospective component rather than to a retrospective component. PMID:23432682

Li, Jian-Bin; Nie, Yan-Gang; Zeng, Min-Xia; Huntoon, Meghan; Smith, Jessi L

2013-01-01

106

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. PMID:22389597

Pawlowski, Andrzej; Guzman, Jose Luis; Rodríguez, Francisco; Berenguel, Manuel; Sánchez, José; Dormido, Sebastián

2009-01-01

107

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

108

A Review of Evaluations of Electronic Event-Based Biosurveillance Systems  

PubMed Central

Electronic event-based biosurveillance systems (EEBS’s) that use near real-time information from the internet are an increasingly important source of epidemiologic intelligence. However, there has not been a systematic assessment of EEBS evaluations, which could identify key uncertainties about current systems and guide EEBS development to most effectively exploit web-based information for biosurveillance. To conduct this assessment, we searched PubMed and Google Scholar to identify peer-reviewed evaluations of EEBS’s. We included EEBS’s that use publicly available internet information sources, cover events that are relevant to human health, and have global scope. To assess the publications using a common framework, we constructed a list of 17 EEBS attributes from published guidelines for evaluating health surveillance systems. We identified 11 EEBS’s and 20 evaluations of these EEBS’s. The number of published evaluations per EEBS ranged from 1 (Gen-Db, GODsN, MiTAP) to 8 (GPHIN, HealthMap). The median number of evaluation variables assessed per EEBS was 8 (range, 3–15). Ten published evaluations contained quantitative assessments of at least one key variable. No evaluations examined usefulness by identifying specific public health decisions, actions, or outcomes resulting from EEBS outputs. Future EEBS assessments should identify and discuss critical indicators of public health utility, especially the impact of EEBS’s on public health response. PMID:25329886

Gajewski, Kimberly N.; Peterson, Amy E.; Chitale, Rohit A.; Pavlin, Julie A.; Russell, Kevin L.; Chretien, Jean-Paul

2014-01-01

109

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

110

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

111

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

112

Using Event Based Data to Assess Vehicle Pedestrian Crash Risk in the Absence of All-Red  

E-print Network

Using Event Based Data to Assess Vehicle Pedestrian Crash Risk in the Absence of All-Red Phase decision making at a signalized intersection? Ã? How effective is the signal timing (particularly "All-Red lane.) #12;4 4 Ã?Data analyzed between 10:30 am to 5 pm. Ã?Typical Yellow duration = 3 secs, All-Red

Minnesota, University of

113

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

Microsoft Academic Search

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,

Franklin Dexter; Ruth E Wachtel; Richard H Epstein

2011-01-01

114

Event-Based Control for Embedded and Networked System Application to a Mini Quadrotor Helicopter using Motion Capture  

E-print Network

Event-Based Control for Embedded and Networked System Application to a Mini Quadrotor Helicopter for controlling the position of a real-time mini quadrotor helicopter using a motion capture system with deported growing interest in research. In particular, the mini quadrotor helicopter

Paris-Sud XI, Université de

115

GPU-EvR: Run-time Event Based Real-time Scheduling Framework on GPGPU Platform  

E-print Network

GPU-EvR: Run-time Event Based Real-time Scheduling Framework on GPGPU Platform Haeseung Lee of California Irvine, Irvine, CA, USA E-mail: {haeseunl, alfaruqu}@uci.edu Abstract--GPU architecture has traditionally been used in graphics application because of its enormous computing ca- pability. Moreover, GPU

Al Faruque, Mohammad Abdullah

116

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

117

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

118

User-Oriented Evaluation of Event-Based Decision Support Systems Jens Pottebaum, Alexander Artikis, Robin Marterer and Georgios Paliouras  

E-print Network

approaches in the literature evaluating AI-based systems -- however, very few studies include `extrinsic et al. [6] as an example). They add value to the field of evaluation research but do not allowUser-Oriented Evaluation of Event-Based Decision Support Systems Jens Pottebaum, Alexander Artikis

Paliouras, George

119

The 32 bit timing unit of a real-time event-based control system for a nuclear fusion experiment  

Microsoft Academic Search

This paper describes the innovative timing unit of a distributed, expandable, real-time, event-based control system for a nuclear fusion experiment. This system is being designed in a tree-type topology, based in VME and CAMAC format modules that produce the timing signals required for the safe operation of the experiment diagnostics and digitizers. It also performs the broadcasting, processing and recording

J. Sousa; A. Combo; A. Batista; C. Correia; C. A. F. Varandas; D. Trotman; J. Waterhouse

1998-01-01

120

Event-based 3D SLAM with a depth-augmented dynamic vision sensor David Weikersdorfer1, David B. Adrian1, Daniel Cremers2 and Jorg Conradt1  

E-print Network

Event-based 3D SLAM with a depth-augmented dynamic vision sensor David Weikersdorfer1, David B-free tracking. Our event- based SLAM algorithm is highly efficient and runs 20 times faster than realtime and mapping (SLAM) is one of the central tasks in robotics and computer vision which enables robots to explore

Kuehnlenz, Kolja

121

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. PMID:23419059

Tam, Joyce W.; Schmitter-Edgecombe, Maureen

2013-01-01

122

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

123

Prediction of event-based stormwater runoff quantity and quality by ANNs developed using PMI-based input selection  

NASA Astrophysics Data System (ADS)

SummaryEvent-based stormwater runoff quantity and quality modeling remains a challenge since the processes of rainfall induced pollutant discharge are not completely understood. The complexity of physically-based models often limits the practical use of quality models in practice. Artificial neural networks (ANNs) are a data driven modeling approach that can avoid the necessity of fully understanding complex physical processes. In this paper, feed-forward multi-layer perceptron (MLP) network, a popular type of ANN, was applied to predict stormwater runoff quantity and quality including turbidity, specific conductance, water temperature, pH, and dissolved oxygen (DO) in storm events. A recently proposed input selection algorithm based on partial mutual information (PMI), which identifies input variables in a stepwise manner, was employed to select input variable sets for the development of ANNs. The ANNs developed via this approach could produce satisfactory prediction of event-based stormwater runoff quantity and quality. In particular, this approach demonstrated a superior performance over the approach involving ANNs fed by inputs selected using partial correlation and all potential inputs in flow modeling. This result suggests the applicability of PMI in developing ANN models. In addition, the ANN for flow outperformed conventional multiple linear regression (MLR) and multiple nonlinear regression (MNLR) models. For an ANN development of turbidity (multiplied by flow rate) and specific conductance, significant improvement was achieved by including a previous 3-week total rainfall amount into their input variable sets. This antecedent rainfall variable is considered a factor in the availability of land surface pollutants for wash-off. A sensitivity analysis demonstrated the potential role of this rainfall variable on modeling particulate solids and dissolved matters in stormwater runoff.

He, Jianxun; Valeo, Caterina; Chu, Angus; Neumann, Norman F.

2011-03-01

124

Event-based criteria in GT-STAF information indices: theory, exploratory diversity analysis and QSPR applications.  

PubMed

Versatile event-based approaches for the definition of novel information theory-based indices (IFIs) are presented. An event in this context is the criterion followed in the "discovery" of molecular substructures, which in turn serve as basis for the construction of the generalized incidence and relations frequency matrices, Q and F, respectively. From the resultant F, Shannon's, mutual, conditional and joint entropy-based IFIs are computed. In previous reports, an event named connected subgraphs was presented. The present study is an extension of this notion, in which we introduce other events, namely: terminal paths, vertex path incidence, quantum subgraphs, walks of length k, Sach's subgraphs, MACCs, E-state and substructure fingerprints and, finally, Ghose and Crippen atom-types for hydrophobicity and refractivity. Moreover, we define magnitude-based IFIs, introducing the use of the magnitude criterion in the definition of mutual, conditional and joint entropy-based IFIs. We also discuss the use of information-theoretic parameters as a measure of the dissimilarity of codified structural information of molecules. Finally, a comparison of the statistics for QSPR models obtained with the proposed IFIs and DRAGON's molecular descriptors for two physicochemical properties log?P and log?K of 34 derivatives of 2-furylethylenes demonstrates similar to better predictive ability than the latter. PMID:23066866

Barigye, S J; Marrero-Ponce, Y; Martínez López, Y; Martínez Santiago, O; Torrens, F; García Domenech, R; Galvez, J

2013-01-01

125

Supporting Event-based Unified Data Access/query over Integrated Data-views for Decision Making in Geographic Information Systems  

E-print Network

Supporting Event-based Unified Data Access/query over Integrated Data- views for Decision Making Computer Science Department, School of Informatics, Indiana University c Physics Department, College integrated data-views in the form of multi-layered map images. Our infrastructure is based on common data

126

Time-Based and Event-Based Prospective Memory in Autism Spectrum Disorder: The Roles of Executive Function and Theory of Mind, and Time-Estimation  

ERIC Educational Resources Information Center

Prospective memory (remembering to carry out an action in the future) has been studied relatively little in ASD. We explored time-based (carry out an action at a pre-specified time) and event-based (carry out an action upon the occurrence of a pre-specified event) prospective memory, as well as possible cognitive correlates, among 21…

Williams, David; Boucher, Jill; Lind, Sophie; Jarrold, Christopher

2013-01-01

127

Prospective memory and ageing paradox with event-based tasks: a study of young, young-old, and old-old participants.  

PubMed

Research on ageing and prospective memory--remembering to do something in the future--has resulted in paradoxical findings, whereby older adults are often impaired in the laboratory but perform significantly better than younger adults in naturalistic settings. Nevertheless, there are very few studies that have examined prospective memory both in and outside the laboratory using the same sample of young and old participants. Moreover, most naturalistic studies have used time-based tasks, and it is unclear whether the prospective memory and ageing paradox extends to event-based tasks. In this study, 72 young (18-30 years), 79 young-old (61-70 years), and 72 old-old (71-80 years) participants completed several event-based tasks in and outside the laboratory. Results showed that the ageing paradox does exist for event-based tasks but manifests itself differently from that in time-based tasks. Thus, younger adults outperformed old-old participants in two laboratory event-based tasks, but there were no age effects for a naturalistic task completed at home (remembering to write the date and time in the upper left corner of a questionnaire). The young and old-old also did not differ in remembering to retrieve a wristwatch from a pocket at the end of the laboratory session. This indicates that the paradox may be due to differences in ongoing task demands in the lab and everyday life, rather than the location per se. The findings call for a concentrated effort towards a theory of cognitive ageing that identifies the variables that do, or do not, account for this paradox. PMID:23030664

Kvavilashvili, Lia; Cockburn, Janet; Kornbrot, Diana E

2013-01-01

128

Simulation of event-based and long-term spatial redistribution of Chernobyl-derived radiocaesium within catchments using geographical information system embedded models  

Microsoft Academic Search

The Chernobyl accident contaminated vast areas of Europe with radiocaesium (137Cs) in 1986. To evaluate long-term and event-based redistribution of Chernobyl-derived 137Cs at the catchment scale, two geographical information system embedded models have been developed. The first model simulates 137Cs redistribution using a monthly time step based on a long-term soil erosion model. The second model simulates lateral radiocaesium transport

Marcel van der Perk; Ondrej Slávik

2003-01-01

129

Diminished Time-Based, but Undiminished Event-Based, Prospective Memory Among Intellectually High-Functioning Adults With Autism Spectrum Disorder: Relation to Working Memory Ability  

PubMed Central

Objective: Prospective memory (PM) is the ability to remember to carry out an intended action. Working memory is the ability to store information in mind while processing potentially distracting information. The few previous studies of PM in autism spectrum disorder (ASD) have yielded inconsistent findings. Studies of working memory ability in ASD have suggested a selective impairment of “visual working memory.” However, it remains unclear whether any such impairment is the result of diminished (domain-specific; visual/verbal) storage capacity or diminished (domain-general) processing capacity. We aim to clarify these issues and explore the relation between PM and working memory in ASD. Method: Seventeen adults with ASD and 17 age- and IQ-matched comparison participants completed experimental measures of both event-based (perform action x when event y occurs) and time-based (perform action a at time b) PM, plus a self-report measure of PM skills. Participants also completed a working memory test battery. Results: Participants with ASD self-reported diminished PM skill, and showed diminished performance on the time-based, but not event-based, PM task. On the working memory test battery, visual but not verbal storage capacity was diminished among participants with ASD, as was processing ability. Whereas visual storage was associated with event-based PM task performance among comparison participants, verbal storage was associated among ASD participants. Conclusions: ASD appears to involve a selective deficit in time-based PM and a selective difficulty with aspects of working memory that depend on the storage of visual information. However, event-based PM may be achieved through compensatory strategies in ASD. PMID:24128041

2013-01-01

130

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. PMID:19763997

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

2009-01-01

131

Simulation of event-based and long-term spatial redistribution of Chernobyl-derived radiocaesium within catchments using geographical information system embedded models  

NASA Astrophysics Data System (ADS)

The Chernobyl accident contaminated vast areas of Europe with radiocaesium (137Cs) in 1986. To evaluate long-term and event-based redistribution of Chernobyl-derived 137Cs at the catchment scale, two geographical information system embedded models have been developed. The first model simulates 137Cs redistribution using a monthly time step based on a long-term soil erosion model. The second model simulates lateral radiocaesium transport at the event scale based on the existing Limburg soil erosion model. This model accounts for surface runoff, soil erosion and deposition, and radiocaesium exchange between the topsoil layer, runoff water, and suspended sediment. Both models have been tested and applied to the Mochovce catchment, western Slovakia. The spatial distribution of 137Cs activity in soil simulated by the long-term model was used as input for the event-based model to assess the changes in 137Cs transport during rainfall events between 1986 and 2002. Soil erosion events in the first months after initial fallout input before ploughing caused a considerable decline in the 137Cs soil inventories, which were estimated at 8·9% of the total initial inventory. The majority of 137Cs transport during rainfall events occurs in particulate form. Both the absolute amounts of particulate 137Cs transport and the fraction of particulate 137Cs transport were shown to be positively related to suspended sediment transport. Between 1986 and 2002, dissolved 137Cs transport has declined by a factor of about 26, which can be largely attributed to the increased sorption to sediment particles. Particulate 137Cs transport has declined by a factor of about two, which can be largely attributed to the decrease in soil 137Cs. The 137Cs inventories in soil have decreased by a factor between three and four at the steep hillslopes, but have remained at about the same level as the initial fallout input at the valley bottoms.

van der Perk, Marcel; Slávik, Ondrej

2003-04-01

132

Fitting an ex-Gaussian function to examine costs in event-based prospective memory: Evidence for a continuous monitoring profile.  

PubMed

Event-based prospective memory (PM) tasks require individuals to remember to perform a deferred action when a target event occurs. PM task requirements can slow ongoing task responses on non-target trials ('costs') under conditions where the defining features of targets are non-focal to the ongoing task, which is indicative that individuals have allocated some form of cognitive control process to the PM task. Recent fits of the ex-Gaussian mathematical function to non-target trial response distributions by prior studies have indicated that these control processes are transiently allocated. In the current paper, fits of the ex-Gaussian function to data reported by Loft and Humphreys (2012) demonstrate a shift in the entire response time distribution (?) and an increase in skew (?) for a non-focal PM condition required to remember to make a PM response if presented with category exemplars, compared to a control condition. This change in ? is indicative of a more continuous PM monitoring profile than that reported by prior studies. In addition, within-subject variability in ? was reliably correlated with PM accuracy, suggesting that these control processes allocated on a regular basis were functional to PM accuracy. In contrast, when the ongoing task directed attention to the defining features of targets (focal PM) there was a trend level increase in ?, but the within-subject variability in ? was not correlated with PM accuracy, consistent with the theoretical premise that focal PM tasks are not as dependent on cognitive control as non-focal PM tasks. PMID:25247678

Loft, Shayne; Bowden, Vanessa K; Ball, B Hunter; Brewer, Gene A

2014-10-01

133

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

134

Stochastic Event-Based Control and Estimation  

E-print Network

­5316 ISRN LUTFD2/TFRT--1095--SE c 2012 by Toivo Henningsson. All rights reserved. Printed in Sweden by Media with both stochastic and set-bounded process and measurement noise terms. A time-varying linear filter gain is optimized using convex semidefinite programming and ellipsoidal over- approximation, given a relative weight

135

Problems in event based engine control  

Microsoft Academic Search

Physically a four cycle spark ignition engine operates on the basis of four engine processes or events: intake, compression, ignition (or expansion) and exhaust. These events each occupy approximately 180° of crank angle. In conventional engine controllers, it is an accepted practice to sample the engine variables synchronously with these events (or submultiples of them). Such engine controllers are often

Elbert Hendricks; Michael Jensen; Alain Chevalier; Thomas Vesterholm

1994-01-01

136

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

137

NIST GCR 02841A Understanding Private-Sector  

E-print Network

, and services resulting from the innovation) Impacts (longer-run impacts on industries, society, and the economy on the business progress and indicators of future economic impact of funded projects and on a biennial basis up outcomes. Economic and policy research studies that examine particular aspects and impacts of the program

Magee, Joseph W.

138

NIST GCR 07-908 Findings from the  

E-print Network

the impact of the program and estimate the returns to the taxpayer. To evaluate whether the program in products, processes, and services from ATP supported projects) · Impacts (long term impacts on U.S. industry, society, and economy) Key features of ATP's evaluation program include: · Business Reporting

139

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

140

NIST GCR 00-803 Determinants of Success in  

E-print Network

Projects Prepared for Economic Assessment Office Advanced Technology Program National Institute of collaborative ventures to the nation's economic strength, the difficulty in making them work, and the role of government in fostering collaborative ventures. The focus of the study is on factors that increase

141

Event-based classification of social media streams  

Microsoft Academic Search

Events play a prominent role in our lives, such that many social media documents describe or are related to some event. Organizing social media documents with respect to events thus seems a promising approach to better manage and organize the ever-increasing amount of content in social media applications. A challenge is to automatize this process so that incoming documents can

Timo Reuter; Philipp Cimiano

2012-01-01

142

Relevant Sampling Applied to Event-Based State-Estimation  

Microsoft Academic Search

To reduce the amount of data transfer in net- worked control systems and wireless sensor networks, measurements are usually sampled only when an event occurs, rather than synchronous in time. Today's event sampling methodologies are triggered by the current value of the sensor. State-estimators are designed to cope with such methods. In this paper we propose a sampling method in

Jan Willem Marck; Joris Sijs

2010-01-01

143

Point process models for event-based speech recognition  

Microsoft Academic Search

Abstract Several strands of research in thefields of linguistics, speechperception, and,neuroethology,suggest,that durational,modelling,of a acoustic event landmark-based,representation,is a scientifically plausible approach,to the automatic,speech,recognition,(ASR) problem.,Adopting,a point process representation,of the speech,signal opens up ASR to a large class of statisti- cal models,that have seen wide,application in the neuroscience,community. In this paper, we formulate several point process models for application to speech recognition, designed

Aren Jansen; Partha Niyogi

2009-01-01

144

Event-based data dissemination control in healthcare  

E-print Network

in healthcare towards preventative care. This shift involves using technology to assist in care provision outside tra- ditional care institutions -- for instance, in a patient's home. To support such an environment, care providers require notification of incidents as they occur. However, health information

Cambridge, University of

145

A novel probabilistic framework for event-based speech recognition  

NASA Astrophysics Data System (ADS)

One of the reasons for unsatisfactory performance of the state-of-the-art automatic speech recognition (ASR) systems is the inferior acoustic modeling of low-level acoustic-phonetic information in the speech signal. An acoustic-phonetic approach to ASR, on the other hand, explicitly targets linguistic information in the speech signal, but such a system for continuous speech recognition (CSR) is not known to exist. A probabilistic and statistical framework for CSR based on the idea of the representation of speech sounds by bundles of binary valued articulatory phonetic features is proposed. Multiple probabilistic sequences of linguistically motivated landmarks are obtained using binary classifiers of manner phonetic features-syllabic, sonorant and continuant-and the knowledge-based acoustic parameters (APs) that are acoustic correlates of those features. The landmarks are then used for the extraction of knowledge-based APs for source and place phonetic features and their binary classification. Probabilistic landmark sequences are constrained using manner class language models for isolated or connected word recognition. The proposed method could overcome the disadvantages encountered by the early acoustic-phonetic knowledge-based systems that led the ASR community to switch to systems highly dependent on statistical pattern analysis methods and probabilistic language or grammar models.

Juneja, Amit; Espy-Wilson, Carol

2003-10-01

146

Heft 175 Sachin Ramesh Patil Regionalization of an Event Based  

E-print Network

Westrich for their indirect support and motivation. I sincerely acknowledge ENWAT International Doctoral greatly honored for being one of his students, his prodigious expertise has unfailingly enlightened my Program of Universitaet Stuttgart for providing the academic framework for this research work. I am

Cirpka, Olaf Arie

147

Semantic-event based analysis and segmentation of wedding ceremonyvideos  

Microsoft Academic Search

Wedding is one of the most important ceremonies in our lives. It symbolizes the birth and creation of a new fam- ily. In this paper, we present a system for automatically segmenting a wedding ceremony video into a sequence of recognized wedding events, e.g., the couple's wedding kiss. Our goal is to develop an automatic tool for users to effi-

Wen-Huang Cheng; Yung-Yu Chuang; Bing-Yu Chen; Ja-Ling Wu; Yin-Tzu Lin

2007-01-01

148

An Event-Based Digital Forensic Investigation Framework  

Microsoft Academic Search

In this paper, we present a framework for digital forensics that includes an investigation process model based on physical crime scene procedures. In this model, each digital device is considered a digital crime scene, which is included in the physical crime scene where it is located. The investigation includes the preservation of the system, the search for digital evidence, and

Brian D. Carrier; Eugene H. Spafford

2004-01-01

149

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

150

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

151

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

152

Event-based Simulation Model for Quantum Optics Experiments  

E-print Network

by treating the electromagnetic field without assuming the existence of photons [3], the photoelectric effect by the cascade process is directed to detector D. The other beam is sent through a 50-50 beam splitter to detectors D0 and D1. Time-coincidence logic is used to establish the emission of the photons by the three

153

Dynamic camouflage event based malicious node detection architecture  

Microsoft Academic Search

Compromised sensor nodes may collude to segregate a specific region of the sensor network preventing event reporting packets\\u000a in this region from reaching the basestation. Additionally, they can cause skepticism over all data collected. Identifying\\u000a and segregating such compromised nodes while identifying the type of attack with a certain confidence level is critical to\\u000a the smooth functioning of a sensor

Kanthakumar Pongaliur; Li Xiao; Alex X. Liu

154

University of Oregon | Public and Government Affairs | 541-346-5020 | gcr@uoregon.edu | gcr.uoregon.edu | rev. 10/15/131 Snapshot 2013  

E-print Network

541 Average SAT verbal score 548 530 Percentage Pell eligible 23.1% Headcount by Race or Ethnicity American Indian and Alaska native 171 1,158 Asian 1,285 5,738 Black-African American 451 2,109 Hispanic Pacific Northwest with membership in the prestigious Association of American Universities, an association

Oregon, University of

155

Atmos. Chem. Phys., 11, 19791988, 2011 www.atmos-chem-phys.net/11/1979/2011/  

E-print Network

Enhancement (GLE) events, based on fits to measurements from ground-based and satellite-borne instruments and middle atmosphere for 58 out of the 66 GLE events recorded by the world-wide neutron monitor network analytical ionization models. The GCR energy spectrum changes on different time scales, with the most

Meskhidze, Nicholas

156

at a rate of 4.8 protons cm 2 --that is, the GCR  

E-print Network

of that isotope; (E) is the flux of neutrons at energy E calculated by LCS (12) at the elevation of Meteor Crater a typical solar cycle. The production rate of 59 Ni was calculat- ed by integration over the energy

Davis, James C.

157

Nuclear fragmentation of GCR-like ions: comparisons between data and PHITS  

Microsoft Academic Search

We present a summary of results from recent work in which we have compared nuclear fragmentation cross section data to predictions of the PHITS Monte Carlo simulation. The studies used beams of 12 C, 35 Cl, 40 Ar, 48 Ti, and 56 Fe at energies ranging from 290 MeV\\/nucleon to 1000 MeV\\/nucleon. Some of the data were obtained at the

Cary Zeitlin; Stephen Guetersloh; Lawrence Heilbronn; Jack Miller; Lembit Sihver; Davide Mancusi; Aki Fukumura; Yoshi Iwata; Takeshi Murakami

2008-01-01

158

p. 2 Time to say goodbye p. 3 GCR: President's report, Chairperson's report,  

E-print Network

Ustinov College as Principal. Over the last six years, Penny has overseen the development of Ustinov from and friendliness motivate everyone who has worked with her to be the best person they can be. We wish her a longWilson, Principal of Ustinov College It is with sadness and fond memories that Ustinov College bids farewell

Wirosoetisno, Djoko

159

Draft Title 40 CFR 191 compliance certification application for the Waste Isolation Pilot Plant. Volume 7: Appendix GCR Volume 2  

SciTech Connect

This report contains the second part of the geological characterization report for the Waste Isolation Pilot Plant. Both hydrology and geochemistry are evaluated. The following aspects of hydrology are discussed: surface hydrology; ground water hydrology; and hydrology drilling and testing. Hydrologic studies at the site and adjacent site areas have concentrated on defining the hydrogeology and associated salt dissolution phenomena. The geochemical aspects include a description of chemical properties of geologic media presently found in the surface and subsurface environments of southeastern New Mexico in general, and of the proposed WIPP withdrawal area in particular. The characterization does not consider any aspect of artificially-introduced material, temperature, pressure, or any other physico-chemical condition not native to the rocks of southeastern New Mexico.

NONE

1995-03-31

160

Quantitative estimates of the effects of cross section uncertainties on the derivation of GCR source composition. [Galactic Cosmic Rays  

NASA Technical Reports Server (NTRS)

Cosmic-ray source abundance uncertainties, resulting from the cross-section uncertainties, are calculated for the elements carbon through nickel. A significant dominance of cross-section errors in the source abundance uncertainties is found for most of the elements considered, even with uncorrelated partial cross-section errors; much larger uncertainties than those reported previously are found for Ca, N, Na, Al, and S. Propagation errors are noted to preclude a significant determination of source abundances for F, Cl, and Mn. A need for an assessment of the existing cosmic-ray propagation models - especially the propagation cross-sections which they employ - is expressed, motivated by recent improvements in the resolution and statistical accuracy of observations.

Hinshaw, G. F.; Wiedenbeck, M. E.

1983-01-01

161

Detecting video events based on action recognition in complex scenes using spatio-temporal descriptor  

Microsoft Academic Search

Event detection plays an essential role in video content analysis and remains a challenging open problem. In particular, the study on detecting human-related video events in complex scenes with both a crowd of people and dynamic motion is still limited. In this paper, we investigate detecting video events that involve elementary human actions, e.g. making cellphone call, putting an object

Guangyu Zhu; Ming Yang; Kai Yu; Wei Xu; Yihong Gong

2009-01-01

162

Event-based integration using on-the-fly matching Anders Moen Hagalisletto  

E-print Network

(CARDX) msg GETCARD msg GETCARD A wildcard(DECK) from DEAL to A from DEAL to A msg DONE msg refresh from DEAL to A msg JOINGAME from A to DEAL msg WIN A wildcard(VALUE) from DEAL to A msg REQUESTCARD from DEAL to A from A to DEAL start from DEAL to A msg LOOSE A play evaluate dealerplay2stand dealerplay submit

Tucci, Sara

163

2013 China-Korea Relay Protection Forum Wide Area Protection Scheme Preventing Cascading Events based on  

E-print Network

to avoid the unexpected trips under overloading situations. Sensitivity based identification methods are presented to improve the traditional zone 3 relay functions, which can differentiate overloading situations from short circuits. A wide area protection scheme is proposed based on this improved im- pedance relay

Chen, Zhe

164

Synthesising Non-Anomalous Event-Based Controllers for Liveness Goals  

E-print Network

of Computing, Imperial College, 180 Queen's Gate, London, SW7 2RH, UK; email: srdipi@doc.ic.ac.uk; V. Braberman.piterman@leicester.ac.uk; S. Uchitel, Department of Computing, Imperial College, 180 Queen's Gate, London, SW7 2RH, UK; su2 or classroom use is granted without fee provided that copies are not made or distributed for profit

Figueira, Santiago

165

Folk Theorems on the Correspondence between State-Based and Event-Based Systems  

NASA Astrophysics Data System (ADS)

Kripke Structures and Labelled Transition Systems are the two most prominent semantic models used in concurrency theory. Both models are commonly believed to be equi-expressive. One can find many ad-hoc embeddings of one of these models into the other. We build upon the seminal work of De Nicola and Vaandrager that firmly established the correspondence between stuttering equivalence in Kripke Structures and divergence-sensitive branching bisimulation in Labelled Transition Systems. We show that their embeddings can also be used for a range of other equivalences of interest, such as strong bisimilarity, simulation equivalence, and trace equivalence. Furthermore, we extend the results by De Nicola and Vaandrager by showing that there are additional translations that allow one to use minimisation techniques in one semantic domain to obtain minimal representatives in the other semantic domain for these equivalences.

Reniers, Michel A.; Willemse, Tim A. C.

166

Implementation of an airline recovery model in an event-based simulation  

E-print Network

Airlines maximize the use of their resources by minimizing the time between consecutive flight legs in their aircraft and crew schedules. As a result, bad weather or unscheduled aircraft maintenance events can have a ...

Rabbani, Fábio Faizi Rahnemay, 1978-

2004-01-01

167

Earthquake source inversion for moderate magnitude seismic events based on GPS simulated high-rate data  

NASA Astrophysics Data System (ADS)

The development of GNSS technology with the potential of high-rate (up to 100Hz) GNSS (GPS, GLONASS, Galileo, Compass) records allows the monitoring of the seismic ground motions. In this study we show the potential of estimating the earthquake magnitude (Mw) and the fault geometry parameters (slip, depth, length, rake, dip, strike) during the propagation of seismic waves based on high-rate GPS network data and using a non-linear inversion algorithm. The examined area is the Valais (South-West Switzerland) where a permanent GPS network of 15 stations (COGEAR and AGNES GPS networks) is operational and where the occurrence of an earthquake of Mw?6 is possible every 80 years. We test our methodology using synthetic events of magnitude 6.0-6.5 corresponding to normal fault according to most of the fault mechanisms of the area, for surface and buried rupture. The epicentres are located in the Valais close to the epicentre of previous historical earthquakes. For each earthquake, synthetic seismic data (velocity records) of 15 sites, corresponding to the current GPS network sites in Valais, were produced. The synthetic seismic data were integrated into displacement time-series. By jointly using these time-series with the Bernese GNSS Software 5.1 (modified), 10Hz sampling rate GPS records were generated assuming a noise of peak-to-peak amplitudes of ±1cm and ±3cm for the horizontal and for the vertical components, respectively. The GPS records were processed and resulted in kinematic time series from where the seismic displacements were derived and inverted for the magnitude and the fault geometry parameters. The inversion results indicate that it is possible to estimate both, the earthquake magnitudes and the fault geometry parameters in real-time (~10 seconds after the fault rupture). The accuracy of the results depends on the geometry of the GPS network and of the position of the earthquake epicentre.

Psimoulis, Panos; Dalguer, Luis; Houlie, Nicolas; Zhang, Youbing; Clinton, John; Rothacher, Markus; Giardini, Domenico

2013-04-01

168

Event Completion: Event Based Inferences Distort Memory in a Matter of Seconds  

ERIC Educational Resources Information Center

We present novel evidence that implicit causal inferences distort memory for events only seconds after viewing. Adults watched videos of someone launching (or throwing) an object. However, the videos omitted the moment of contact (or release). Subjects falsely reported seeing the moment of contact when it was implied by subsequent footage but did…

Strickland, Brent; Keil, Frank

2011-01-01

169

An Architecture for a Task-Oriented Surveillance System: A Service and Event-Based Approach  

Microsoft Academic Search

Due to the increasing threat posed by crime, industrial espionage and even terrorism, video surveillance systems have become more important and powerful during the last years. While most commercially available surveillance systems have to be managed by human operators, who constantly monitor all video streams, several experimental systems from different research groups already include robust video processing approaches for (semi-)

J. Mossgraber; F. Reinert; H. Vagts

2010-01-01

170

Eva: An Event-Based Framework for Developing Specialized Communication Protocols  

Microsoft Academic Search

This paper presents a framework for the development of higher level communication protocols that provides extra functionalities (e.g. one-to-many ordered delivery, atomic delivery, etc.) not supplied by standard off-the-shelf low- er level communication protocols (e.g. the TCP\\/IP suite of protocols). The framework is based on the event chan- nel abstraction which allows circumventing the main draw- backs of the layered-based

Francisco Vilar Brasileiro; Fabíola Greve; Frederic Tronel; Michel Hurfin; Jean-pierre Le Narzul

2001-01-01

171

The Relationship between Event-Based Prospective Memory and Ongoing Task Performance in Chimpanzees (Pan troglodytes)  

PubMed Central

Prospective memory is remembering to do something at a future time. A growing body of research supports that prospective memory may exist in nonhuman animals, but the methods used to test nonhuman prospective memory differ from those used with humans. The current work tests prospective memory in chimpanzees using a method that closely approximates a typical human paradigm. In these experiments, the prospective memory cue was embedded within an ongoing task. Tokens representing food items could be used in one of two ways: in a matching task with pictures of items (the ongoing task) or to request a food item hidden in a different location at the beginning of the trial. Chimpanzees had to disengage from the ongoing task in order to use the appropriate token to obtain a higher preference food item. In Experiment 1, chimpanzees effectively matched tokens to pictures, when appropriate, and disengaged from the ongoing task when the token matched the hidden item. In Experiment 2, performance did not differ when the target item was either hidden or visible. This suggested no effect of cognitive load on either the prospective memory task or the ongoing task, but performance was near ceiling, which may have contributed to this outcome. In Experiment 3, we created a more challenging version of the task. More errors on the matching task occurred before the prospective memory had been carried out, and this difference seemed to be limited to the hidden condition. This finding parallels results from human studies and suggests that working memory load and prospective memory may have a similar relationship in nonhuman primates. PMID:25372809

Evans, Theodore A.; Perdue, Bonnie; Beran, Michael J.

2014-01-01

172

Prediction problem for target events based on the inter-event waiting time  

NASA Astrophysics Data System (ADS)

In this paper we address the problem of forecasting the target events of a time series given the distribution ? of time gaps between target events. Strong earthquakes and stock market crashes are the two types of such events that we are focusing on. In the series of earthquakes, as McCann et al. show [W.R. Mc Cann, S.P. Nishenko, L.R. Sykes, J. Krause, Seismic gaps and plate tectonics: seismic potential for major boundaries, Pure and Applied Geophysics 117 (1979) 1082-1147], there are well-defined gaps (called seismic gaps) between strong earthquakes. On the other hand, usually there are no regular gaps in the series of stock market crashes [M. Raberto, E. Scalas, F. Mainardi, Waiting-times and returns in high-frequency financial data: an empirical study, Physica A 314 (2002) 749-755]. For the case of seismic gaps, we analytically derive an upper bound of prediction efficiency given the coefficient of variation of the distribution ?. For the case of stock market crashes, we develop an algorithm that predicts the next crash within a certain time interval after the previous one. We show that this algorithm outperforms random prediction. The efficiency of our algorithm sets up a lower bound of efficiency for effective prediction of stock market crashes.

Shapoval, A.

2010-11-01

173

An Event-Based Coordination Model for Context-Aware Applications  

E-print Network

interactions, objectives, mood). The versatility of this notion of context has lead to a focus on context music clips in the living room. Bob has however noted an undesirable behavior. Sometimes he can watch hears the music of his roommate Alice, who has a similar laptop. This is because Alice has programmed

Paris-Sud XI, Université de

174

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

175

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. PMID:23759402

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

2013-01-01

176

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

E-print Network

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 ...

Holmes, David W.

177

Spatio-Temporal and Events Based Analysis of Topic Popularity in Twitter  

E-print Network

10 million users and a comprehensive scraping of 196 million tweets, we perform a rigorous temporal" whereas other topics die an early death. The network Permission to make digital or hard copies of all data set of tweets and user information taken from Twitter. A key strength of our study is that we

Bagchi, Amitabha

178

Event-Based Modeling of Driver Yielding Behavior at Unsignalized Crosswalks  

PubMed Central

This research explores factors associated with driver yielding behavior at unsignalized pedestrian crossings and develops predictive models for yielding using logistic regression. It considers the effect of variables describing driver attributes, pedestrian characteristics and concurrent conditions at the crosswalk on the yield response. Special consideration is given to ‘vehicle dynamics constraints’ that form a threshold for the potential to yield. Similarities are identified to driver reaction in response to the ‘amber’ indication at a signalized intersection. The logit models were developed from data collected at two unsignalized mid-block crosswalks in North Carolina. The data include ‘before’ and ‘after’ observations of two pedestrian safety treatments, an in-street pedestrian crossing sign and pedestrian-actuated in-roadway warning lights. The analysis suggests that drivers are more likely to yield to assertive pedestrians who walk briskly in their approach to the crosswalk. In turn, the yield probability is reduced with higher speeds, deceleration rates and if vehicles are traveling in platoons. The treatment effects proved to be significant and increased the propensity of drivers to yield, but their effectiveness may be dependent on whether the pedestrian activates the treatment. The results of this research provide new insights on the complex interaction of pedestrians and vehicles at unsignalized intersections and have implications for future work towards predictive models for driver yielding behavior. The developed logit models can provide the basis for representing driver yielding behavior in a microsimulation modeling environment. PMID:21852892

Schroeder, Bastian J.; Rouphail, Nagui M.

2011-01-01

179

Event-Based Modeling of Driver Yielding Behavior at Unsignalized Crosswalks.  

PubMed

This research explores factors associated with driver yielding behavior at unsignalized pedestrian crossings and develops predictive models for yielding using logistic regression. It considers the effect of variables describing driver attributes, pedestrian characteristics and concurrent conditions at the crosswalk on the yield response. Special consideration is given to 'vehicle dynamics constraints' that form a threshold for the potential to yield. Similarities are identified to driver reaction in response to the 'amber' indication at a signalized intersection. The logit models were developed from data collected at two unsignalized mid-block crosswalks in North Carolina. The data include 'before' and 'after' observations of two pedestrian safety treatments, an in-street pedestrian crossing sign and pedestrian-actuated in-roadway warning lights.The analysis suggests that drivers are more likely to yield to assertive pedestrians who walk briskly in their approach to the crosswalk. In turn, the yield probability is reduced with higher speeds, deceleration rates and if vehicles are traveling in platoons. The treatment effects proved to be significant and increased the propensity of drivers to yield, but their effectiveness may be dependent on whether the pedestrian activates the treatment.The results of this research provide new insights on the complex interaction of pedestrians and vehicles at unsignalized intersections and have implications for future work towards predictive models for driver yielding behavior. The developed logit models can provide the basis for representing driver yielding behavior in a microsimulation modeling environment. PMID:21852892

Schroeder, Bastian J; Rouphail, Nagui M

2011-07-01

180

A 1-year long event-based isotopic composition of precipitation in Bolivia: observations and modelling  

NASA Astrophysics Data System (ADS)

Over the last years, an increasing number of studies combining both observations and modelling works has been carried out to determine and to decipher the different climate controls on the isotopic composition of tropical precipitation. Most of those studies have dealt with seasonal to interannual timescales. We present here the isotopic composition of precipitation collected on an event basis from September 1999 to August 2000 in the Zongo Valley (16 degrees S, 67 degrees W) from 945 to 4750 m. The delta records are fairly similar from one station to another and clearly show an intra-month variability superimposed on the seasonal cycle. Conversely, precipitation distribution and occurrence of extremes largely differ from one station to another, revealing that local precipitation has no control on delta. We thus explore potential regional controls (origin of airmasses, precipitation history along trajectories) using back-trajectories calculations. Deuterium excess available from one station is also examined as a proxy of water vapor recycling. Based on a simulation zoomed over South America (60km resolution) and nudged by reanalyzed winds performed with the LMDZ-iso model, which is able to reproduce well the observations in the Zongo Valley, we examine in deeper details the climate controls that could explain the strong intra-seasonal variations in the isotopic composition of precipitation.

Vimeux, Francoise; Tremoy, Guillaume; Risi, Camille

2010-05-01

181

EVA: An EVent Algebra Supporting Adaptivity and Collaboration in Event-Based Systems  

Microsoft Academic Search

In applications such as digital libraries, stock tickers, traffic control, or supply chain management, composite events have been introduced to enable to capture rich situations. Composite events seem to follow a common semantics. However, on closer inspection we observed that the evaluation semantics of events differs substantially from system to system. In this paper, we propose a parameterized event that

Annika Hinze; Agnès Voisard

182

An event-based comparison of two types of automated-recording, weighing bucket rain gauges  

NASA Astrophysics Data System (ADS)

A multiyear comparison of two types of automated-recording, weighing bucket rain gauges was conducted using precipitation data collected at the United States Department of Agriculture, Agricultural Research Service's Walnut Gulch Experimental Watershed in southeastern Arizona. The comparison was part of the conversion of all rain gauges on the watershed from an analog-recording, mechanical-weighing rain gauge to a data logger controlled, digital-recording, electronic-weighing rain gauge with radiotelemetry. This comparison applied to nine pairs of analog and digital rain gauges that were in coincident operation during a 5-year period, 1 January 2000 to 31 December 2004. This study found that (1) high errors in event intensities may be produced when analog charts are digitized at short time intervals; (2) dual digital rain gauges recorded precipitation equivalently; (3) for several different measures of precipitation, the analog and digital data were equivalent; and (4) implications for the rainfall-runoff model, Kinematic and Erosion Runoff model (KINEROS), showed a limited but significant effect in modeled runoff due to differences between analog and digital rain gauge input precipitation intensities. This study provided a useful analysis for long-term rain gauge networks that have recently converted, or will soon convert, from analog to digital technology. Understanding these differences and similarities will benefit interpretation of the combined long-term precipitation record and provide insights into the impacts on hydrologic modeling.

Keefer, T. O.; Unkrich, C. L.; Smith, J. R.; Goodrich, D. C.; Moran, M. S.; Simanton, J. R.

2008-05-01

183

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. PMID:23881139

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

2013-01-01

184

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

E-print Network

to the use of direct flare observations, we evaluate the probabilities of large-energy solar events on magnetically active, young Sun-like stars have energies and frequencies markedly in excess of strong solar, based on records of sunspots and on statistical arguments, that solar flares in the past four centuries

Wehrli, Bernhard

185

Event-Based Analysis of People's Activities and Behavior Using Flickr and Panoramio Geotagged Photo Collections  

Microsoft Academic Search

Photo-sharing websites such as Flickr and Panoramio contain millions of geotagged images contributed by people from all over the world. Characteristics of these data pose new challenges in the domain of spatio-temporal analysis. In this paper, we define several different tasks related to analysis of attractive places, points of interest and comparison of behavioral patterns of different user communities on

Slava Kisilevich; Milos Krstajic; Daniel A. Keim; Natalia V. Andrienko; Gennady L. Andrienko

2010-01-01

186

Event based analysis of chlorothalonil concentrations following application to managed turf.  

PubMed

Chlorothalonil concentrations exceeding acute toxicity levels for certain organisms have been measured in surface water discharge events from managed turf watersheds. The duration of exceedence and the timing of these events related to precipitation/runoff and time since application, however, have not been explored. Chlorothalonil concentrations were measured from discharge waters draining a managed turf watershed in Duluth, Minnesota, USA, between 2003 and 2009. The median chlorothalonil concentration was 0.58?µg/L. Approximately 2% of all measured concentrations exceeded the 7.6?µg/L median lethal concentration (LC50) acute toxicity level for rainbow trout. One-twentieth the LC50 concentration, equivalent to the level of concern (0.38?µg/L) for endangered species, was exceeded 31% of the time during the present study. The concentrations that exceeded the LC50 threshold were associated with eight rainfall/runoff events. Low dose exposures are a more important biological concern than acute occurrences. Exceedence concentrations associated with acute effects were significantly (p?

King, Kevin W; Balogh, James C

2013-03-01

187

Event-Based SOAP Message Validation for WS-SecurityPolicy-Enriched Web Services  

Microsoft Academic Search

To enable checking of SOAP messages for compliance to a given security policy, extensions to the classical ,,Schema-only'' validation of SOAP messages are required. These extensions check, if the WS-Security elements found in a SOAP message fulfill the Web Service security specification that is laid down in the WS-SecurityPolicy document. In this paper, we discuss to what extent the proposed

Nils Gruschka; Norbert Luttenberger; Ralph Herkenhoener

2006-01-01

188

Alcohol, drugs, and condom use among drug offenders: An event-based analysis  

PubMed Central

Background Studies of the association between substance use and condom use in specific sexual encounters often do not separate the effects of alcohol and different types of drugs. Because the pharmacological effects and social settings of various substances differ, their effects on unprotected intercourse may vary as well. Goal This study examined the relationship between alcohol and drug use and the use of condoms in sexual encounters with casual partners in a high-risk population of drug offenders Design Participants in court-ordered drug diversion programs (n=536; 26% female) completed a questionnaire in which they reported on the circumstances of their most recent sexual encounter with a casual partner. Results In multivariate logistic models, alcohol use in conjunction with sex was not related to decreased condom use in either men or women. Amphetamines (smoked or injected) were associated with decreased condom use, while cocaine, marijuana, and orally-administered amphetamines were not significantly associated with condom use. Conclusions In this high-risk sample, links between substance use and unprotected sex differ with type of drug used. PMID:17928167

Leigh, Barbara C.; Ames, Susan L.; Stacy, Alan W.

2008-01-01

189

A Program Structure for Event-Based Speech Synthesis by Rules within a Flexible Segmental Framework.  

ERIC Educational Resources Information Center

A program structure based on recently developed techniques for operating system simulation has the required flexibility for use as a speech synthesis algorithm research framework. This program makes synthesis possible with less rigid time and frequency-component structure than simpler schemes. It also meets real-time operation and memory-size…

Hill, David R.

1978-01-01

190

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

191

Event-based Approach to Money Laundering Data Analysis and Visualization  

E-print Network

knowledge of the crime for successful detection. As a result, they are less effective in detecting patterns. The effectiveness of the proposed method is demonstrated on a money laundering case from Taiwan. Categories, offenders play different roles for various illegal activities [19]. These offenders are usually connected

Si, Yain Whar "Lawrence"

192

An event-based model of superspreading in epidemics Alex Jamesa  

E-print Network

to implicate superspreading in human diseases including SARS, Ebola haemorrhagic fever (HF), measles of susceptibles in each time step (generation), and the epidemic spreads generation-by-generation. Individuals

James, Alex

193

Age-related impairment in an event-based prospective-memory task.  

PubMed

Slides of famous people were presented to participants with the instructions to name each face and circle the trial number if the person was wearing glasses (prospective-memory target event). Participants in their 50s and 60s (n = 56) were more successful than participants in their 70s and 80s (n = 59) at both the naming an prospective-memory tasks. An age-related increase in the probability of forgetting replicated an earlier prospective-memory study (E. A. Maylor, 1993); in the present case, there was also an age-related decrease in the probability of recovery. These effects of age remained significant after other measures of current ability were taken into account, including intelligence, speed, and naming performance. For participants who were in both the earlier study (E. A. Maylor, 1993) and this study (n = 65), the correlation between prospective-memory performance on the 2 occasions was significant but only for younger participants. Performance in the prospective-memory task was entirely unrelated to performance in the naming task. PMID:8726372

Maylor, E A

1996-03-01

194

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

195

Event-Driven Response Architecture for Event-Based Vijay Dheap1,2  

E-print Network

of user-choice, system defaults, and available action services. We have implemented a prototype of our is about Mary, who plans to pick up her mother from the local airport. Mary arrives at the airport 20 at the airport, Mary has very few options other than waiting. Mary may have preferred to carry out other tasks

Ward, Paul A.S.

196

Rediscovering Workflow Models from Event-Based Data using Little Thumb  

E-print Network

to make workflow management more flexible (e.g., [2,4,20]). Most of the research in this area is devoted to techniques to increase the flexibility either by allowing for ad-hoc changes (as reflected by workflow to flexibility. We argue that many problems are resulting from a discrepancy between workflow design (i

van der Aalst, Wil

197

An empirical-stochastic, event-based program for simulating inflow from a tributary network  

E-print Network

interested in large flood peaks to assess flood risk and design flood control [U.S. Army Corps of Engineers the zero-damage stage, that transport sediments of differing caliber, inundate and scour flood- plains in flood events. It incorporates seasonality, event basis, and correlation in flood occurrence and flood

California at Santa Barbara, University of

198

Prediction and evaluation of solar particle events based on precursor information.  

PubMed

Protection from the radiation effects of solar particle events for deep space mission crews requires a warning system to observe solar flares and predict subsequent charged particle fluxes. Such a system relates precursor information observed in each flare to the intensity, delay, and duration of the subsequent Solar Particle Event (SPE) at other locations in the solar system. A warning system of this type is now in operation at the NOAA Space Environment Services Center in Boulder, Colorado for support of space missions. It has been used to predict flare particle fluxes at the earth for flares of Solar Cycle 22. The flare parameters used and the effectiveness of the current warning system, based on Solar Cycle 22 experience, are presented, with an examination of the shortcomings. Needed improvements to the system include more complete observations of solar activity, especially information on the occurrences of solar mass ejections; and consideration of the effects of propagation conditions in the solar corona and interplanetary medium. Requirements for solar observations and forecasting systems on board the spacecraft are discussed. PMID:11537021

Heckman, G R; Kunches, J M; Allen, J H

1992-01-01

199

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

200

Event-based motion control for mobile sensor networks Zack Butler and Daniela Rus  

E-print Network

of the network itself. We envision that when a major incident occurs (such as a fire or chemical spill to mitigate sensor failure and to enhance the group's sensing capabilities. When the events occur frequently), the sensors will be able to cluster around the incident. This will ensure good coverage of the event

Butler, Zack

201

An event-based approach to understanding decadal fluctuations in the Atlantic meridional overturning circulation  

NASA Astrophysics Data System (ADS)

Many previous studies have shown that unforced climate model simulations exhibit decadal-scale fluctuations in the Atlantic meridional overturning circulation (AMOC), and that this variability can have impacts on surface climate fields. However, the robustness of these surface fingerprints across different models is less clear. Furthermore, with the potential for coupled feedbacks that may amplify or damp the response, it is not known whether the associated climate signals are linearly related to the strength of the AMOC changes, or if the fluctuation events exhibit nonlinear behaviour with respect to their strength or polarity. To explore these questions, we introduce an objective and flexible method for identifying the largest natural AMOC fluctuation events in multicentennial/multimillennial simulations of a variety of coupled climate models. The characteristics of the events are explored, including their magnitude, meridional coherence and spatial structure, as well as links with ocean heat transport and the horizontal circulation. The surface fingerprints in ocean temperature and salinity are examined, and compared with the results of linear regression analysis. It is found that the regressions generally provide a good indication of the surface changes associated with the largest AMOC events. However, there are some exceptions, including a nonlinear change in the atmospheric pressure signal, particularly at high latitudes, in HadCM3. Some asymmetries are also found between the changes associated with positive and negative AMOC events in the same model. Composite analysis suggests that there are signals that are robust across the largest AMOC events in each model, which provides reassurance that the surface changes associated with one particular event will be similar to those expected from regression analysis. However, large differences are found between the AMOC fingerprints in different models, which may hinder the prediction and attribution of such events in reality.

Allison, Lesley; Hawkins, Ed; Woollings, Tim

2014-09-01

202

An Event-based Platform for Collaborative Threats Detection and Monitoring  

E-print Network

Aniello, Giuseppe A. Di Luna, Roberto Baldoni Cyber Intelligence and Information Security Research Centre from the same cyber crimes. Sharing and correlating information could help them in early detecting, 2014 #12;1. Introduction Threats such as frauds and cyber attacks can have serious and mea- surable

Tucci, Sara

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

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

205

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

206

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

207

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. PMID:24619314

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

2013-01-01

208

Mode of action of the gcr9 and cat3 mutations in restoring the ability of Saccharomyces cerevisiae tps1 mutants to grow on glucose  

Microsoft Academic Search

Mutations in the TPS1 gene, which encodes trehalose-6-P synthase, cause a glucose-negative phenotype in Saccharomyces cerevisiae. Antimycin A or disruption of the QCR9 gene, which encodes one subunit of the cytochrome bc1 complex, restore the ability to grow in glucose-containing media. Under these conditions the cell excreted a large amount of glycerol, corresponding to about 20% of the glucose taken

Miguel A. Blázquez; Carlos Gancedo

1995-01-01

209

GCR and SPE organ doses in deep space with different shielding: Monte Carlo simulations based on the FLUKA code coupled to anthropomorphic phantoms  

Microsoft Academic Search

Astronauts’ exposure to space radiation is of high concern for long-term missions, especially for those in deep space such as possible travels to Mars. In these cases shielding optimization is a crucial issue, and simulations based on radiation transport codes and anthropomorphic model phantoms can be of great help. In this work the FLUKA Monte Carlo code was coupled with

F. Ballarini; G. Battistoni; F. Cerutti; A. Fassò; A. Ferrari; E. Gadioli; M. V. Garzelli; A. Mairani; A. Ottolenghi; H. G. Paretzke; V. Parini; M. Pelliccioni; L. Pinsky; P. R. Sala; D. Scannicchio; S. Trovati; M. Zankl

2006-01-01

210

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

211

Getting to Know Your Neighbors: Unsupervised Learning of Topography from Real-World, Event-Based Input  

Microsoft Academic Search

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

Martin Boerlin; Tobi Delbrück; Kynan Eng

2009-01-01

212

Event-based control and wireless sensor network for greenhouse diurnal temperature control: A simulated case study  

Microsoft Academic Search

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 green-houses 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

Andrzej Pawlowski; José Luis Guzman; Francisco Rodríguez; Manuel Berenguel; José Sánchez; Sebastián Dormido

2008-01-01

213

Development of an algorithm for the detection of seismic events based on GPS records: Case study Tohoku-Oki earthquake  

NASA Astrophysics Data System (ADS)

The occurrence of strong earthquakes in the last decade (Sumatra, 2004; Tohoku-Oki, 2011, etc.) and the availability of high-rate GPS records (up to 100 Hz) with a kinematic positioning accuracy of 1-5 cm, show the potential of using GPS networks for the detection of earthquake. At GGL, ETH Zurich, a first version of algorithm for the detection of seismic motions based on GPS network records has been developed. The developed algorithm mainly consists of two parts. After removing the low-frequency signal from the GPS kinematic time series the noise level is estimated, for a time interval with no motion. This noise level is used to detect the seismic signal. To improve the reliability of the detection, the signal of neighbouring GPS stations are then checked for a similar consistent signal. The algorithm has been developed within the framework of the Bernese GNSS Software 5.1 (modified) and was used for the detection of ground motions in the GPS time series previously derived for the Tohoku-Oki earthquake. The kinematic GPS time series (north, east, up) were generated for >800 stations based on GPS observations with a 1-sec sampling rate. Using the developed method the earthquake was correctly detected in the GPS records throughout the entire network. The detected signal in the GPS time series seems to correspond to different seismic waves (e.g. P-wave, S-wave, etc.) depending among others on the distance of each GPS station from the epicentre.

Psimoulis, Panos; Meindl, Michael; Houlie, Nicolas; Rothacher, Markus

2013-04-01

214

Using Event-Based Translation to Support Dynamic Protocol Evolution Nathan D. Ryan and Alexander L. Wolf  

E-print Network

-component commu- nication. Whether these protocols are based on a broadly used "standard" or are specially of this work is to enable dy- namic communication protocols, which is to say, to al- low a distributed application to continue functioning even when the communication protocols used by its dis- tributed components

Wolf, Alexander L.

215

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

216

An event-based vibration control for a two-link flexible robotic arm: Numerical and experimental observations  

NASA Astrophysics Data System (ADS)

Flexible robot manipulators have numerous advantages over their rigid counterparts. They have increased payload-to-weight ratio, they run at higher speeds, use less energy and smaller actuators, and they are safer during interaction with their environments. On the other hand, light design combined with external effects result in components which can oscillate with excessive amplitudes. These oscillations cause deviation from the desired path and long idle periods between tasks in order to perform the intended operation safely and accurately. This paper is on an investigation into the effectiveness of a vibration control technique for a two-link flexible robotic arm. Variable stiffness control (VSC) technique is used to control the excessive oscillations. Owing to its dissipative nature, the technique is stable, it is relatively insensitive to significant parameter changes and suitable to be implemented on existing robots. This research considers that the source of the flexibility is either the joints or the links or both. Simulation results of the response of the arm are presented to show the versatility of the proposed control technique. Experiments are performed on a laboratory prototype and the results are presented to test the validity of simulations.

Özer, Abdullah; Eren Semercigil, S.

2008-06-01

217

On event-based PI control of first-order processes Ubaldo Tiberi, Jose Araujo, Karl Henrik Johansson  

E-print Network

Control Systems (NCS), Adaptive Control. 1. INTRODUCTION The proportional-integral-derivative (PID version of PI controller for networked control systems. Although PIDPLUS has been introduced to deal- loop system where such a controller is used has never been performed, here the performance

Johansson, Karl Henrik

218

Integrated Data Products to Forecast, Mitigate, and Educate for Natural Hazard Events Based on Recent and Historical Observations  

NASA Astrophysics Data System (ADS)

Immediately following a damaging or fatal natural hazard event there is interest to access authoritative data and information. The National Geophysical Data Center (NGDC) maintains and archives a comprehensive collection of natural hazards data. The NGDC global historic event database includes all tsunami events, regardless of intensity, as well as earthquakes and volcanic eruptions that caused fatalities, moderate damage, or generated a tsunami. Examining the past record provides clues to what might happen in the future. NGDC also archives tide gauge data from stations operated by the NOAA/NOS Center for Operational Oceanographic Products and Services and the NOAA Tsunami Warning Centers. In addition to the tide gauge data, NGDC preserves deep-ocean water-level, 15-second sampled data as collected by the Deep-ocean Assessment and Reporting of Tsunami (DART) buoys. Water-level data provide evidence of sea-level fluctuation and possible inundation events. NGDC houses an extensive collection of geologic hazards photographs available online as digital images. Visual media provide invaluable pre- and post-event data for natural hazards. Images can be used to illustrate inundation and possible damage or effects. These images are organized by event or hazard type (earthquake, volcano, tsunami, landslide, etc.), along with description and location. They may be viewed via interactive online maps and are integrated with historic event details. The planning required to achieve collection and dissemination of hazard event data is extensive. After a damaging or fatal event, NGDC begins to collect and integrate data and information from many people and organizations into the hazards databases. Sources of data include the U.S. NOAA Tsunami Warning Centers, the U.S. Geological Survey, the U.S. NOAA National Data Buoy Center, the UNESCO Intergovernmental Oceanographic Commission (IOC), Smithsonian Institution's Global Volcanism Program, news organizations, etc. NGDC then works to promptly distribute data and information for the appropriate audience. For example, when a major tsunami occurs, all of the related tsunami data are combined into one timely resource. NGDC posts a publicly accessible online report which includes: 1) event summary; 2) eyewitness and instrumental recordings from preliminary field surveys; 3) regional historical observations including similar past events and effects; 4) observed water heights and calculated tsunami travel times; and 5) near-field effects. This report is regularly updated to incorporate the most recent news and observations. Providing timely access to authoritative data and information ultimately benefits researchers, state officials, the media and the public.

McCullough, H. L.; Dunbar, P. K.; Varner, J. D.

2011-12-01

219

Bio-inspired Event Based Motion Detection for Traffic Safety in a Close-Real Automotive Environment  

Microsoft Academic Search

In this paper a bio-inspired and automotive-compliant system for traffic safety is presented. This work is the first complete application of Address Event Representation (AER) techniques to a real world problem in an automotive environment. The main goal is to detect hands driver activity in the driving wheel area. Our system is based on AER, where the more relevant visual

Cristina Conde; Eduardo Orbe; Isaac Martin de Diego; Enrique Cabello

2011-01-01

220

Interplanetary crew dose estimates for worst case solar particle events based on historical data for the Carrington flare of 1859  

Microsoft Academic Search

Over the past two decades, hypothetical models of “worst-case” solar particle event (SPE) spectra have been proposed in order to place an upper bound on radiation doses to critical body organs of interplanetary crews on deep space missions. These event spectra are usually formulated using hypothetical extrapolations of space measurements for previous large events. Here we take a different approach.

Daniel L. Stephens Jr.; Lawrence W. Townsend; Jennifer L. Hoff

2005-01-01

221

Event-based Green Scheduling of Radiant Systems in Buildings Truong X. Nghiem, George J. Pappas and Rahul Mangharam  

E-print Network

of electric radiant heating systems while maintaining indoor thermal comfort. This paper develops an event the disturbances and is thus more suitable for building systems. The effectiveness of the new strategy a customer is charged for both its electricity consumption and its peak demand over the billing cycle

Pappas, George J.

222

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

223

Event-based estimation of water budget components using a network of multi-sensor capacitance probes  

Microsoft Academic Search

A new approach was developed for estimating vertical soil water fluxes using soil water content time series data. Instead of a traditional fixed time interval, this approach utilizes the time interval between two sequential minima of the soil water storage time series to identify groundwater recharge events and calculate components of the soil water budget. We calculated water budget components:

Andrey Guber; Timothy Gish; Yakov Pachepsky; Lynn McKee; Thomas Nicholson; Ralph Cady

2011-01-01

224

Medical mitigation strategies for acute radiation exposure during spaceflight.  

PubMed

The United States Government has recently refocused their space program on manned missions to the Moon by 2018 and later to Mars. While there are many potential risks associated with exploration-class missions, one of the most serious and unpredictable is the effect of acute space radiation exposure, and the space program must make every reasonable effort to mitigate this risk. The two cosmic sources of radiation that could impact a mission outside the Earth's magnetic field are solar particle events (SPE) and galactic cosmic radiation (GCR). Either can cause acute and chronic medical illness. Numerous researchers are currently examining the ability of GCR exposure to induce the development of genetic changes that lead to malignancies and other delayed effects. However, relatively little has been published on the medical management of an acute SPE event and the potential impact on the mission and crew. This review paper will provide the readers with medical management options for an acute radiation event based on recommendations from the Department of Homeland Security (DHS), Centers for Disease Control (CDC), and evidence-based critical analysis of the scientific literature. It is the goal of this paper to stimulate debate regarding the definition of safety parameters for exploration-class missions to determine the level of medical care necessary to provide for the crew that will undertake such missions. PMID:16491581

Epelman, Slava; Hamilton, Douglas R

2006-02-01

225

Reconstructing high-magnitude/low-frequency landslide events based on soil redistribution modelling and a Late-Holocene sediment record from New Zealand  

NASA Astrophysics Data System (ADS)

A sediment record is used, in combination with shallow landslide soil redistribution and sediment-yield modelling, to reconstruct the incidence of high-magnitude/low-frequency landslide events in the upper part of a catchment and the history of a wetland in the lower part. Eleven sediment cores were obtained from a dune-impounded wetland at Te Henga, west Auckland, northern New Zealand. Sediment stratigraphy and chronology were interpreted by radiocarbon dating, foraminiferal analysis, and provisional tephrochronology. Gradual impoundment of the wetland began c. 6000 cal yr BP, coinciding with the start of a gentle sea-level fall, but complete damming and initial sedimentation did not begin until c. 1000 cal yr BP. After damming, four well-defined sediment pulses occurred and these are preserved in the form of distinct clay layers in most of the sediment cores. For interpreting the sediment pulses, a physically based landslide model was used to determine spatially distributed relative landslide hazard, applicable at the catchment scale. An empirical landslide-soil redistribution component was added and proved able to determine the volumes and spatial pattern of eroded and deposited soil material, sediment delivery ratio and the impact on total catchment sediment yield. Sediment volumes were calculated from the wetland cores and corresponding landslide scenarios are defined through back-analysis of modelled sediment yield output. In general, at least four major high-magnitude landslide events, both natural and intensified by forest clearance activities, occurred in the catchment upstream of Te Henga Wetland during the last c. 1000 years. The spatial distribution of modelled critical rainfall values for the catchment can be interpreted as an expression of shallow landslide hazard. The magnitude of the sediment pulses represented in the wetland can be back-calculated to critical rainfall thresholds representing a shallow landslide model scenario.

Claessens, L.; Lowe, D. J.; Hayward, B. W.; Schaap, B. F.; Schoorl, J. M.; Veldkamp, A.

2006-03-01

226

High Temporal Frequency Biophysical and Structural Vegetation Information from Multiple Remote Sensing Sensors can Support Modelling of Event Based Hillslope Erosion in Queensland  

NASA Astrophysics Data System (ADS)

This study demonstrates the potential applicability of high temporal frequency information on the biophysical condition of the vegetation from a time series of the global Moderate Resolution Imaging Spectroradiometer (MODIS) Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR) from 2000 to 2006 (collection 4; 8-day composites in 1 km spatial resolution) to improve modelling of soil loss in a tropical, semi-arid catchment in Queensland. Combining the biophysical information from the MODIS FPAR with structural vegetation information from the Geoscience Laser Altimeter System on the Ice, Cloud, and land Elevation Satellite (ICESat) for six vegetation structural categories identified from a Landsat Thematic Mapper 5 (TM) and Enhanced Thematic Mapper 7 (ETM+) woody foliage projective cover product representing floristically and structurally homogeneous areas, dynamic vegetative cover factor (vCf) estimates were calculated. The dynamic vCf were determined in accordance with standard calculation methods used in erosion models worldwide. Time series of dynamic vCf were integrated into a regionally improved version of the Universal Soil Loss Equation (USLE) to predict daily soil losses for the study area. Resulting time series of daily soil loss predictions averaged over the study area coincided well with measures of total suspended solids (TSS) (mg/l) at a gauge at the outlet of the catchment for three wet seasons (R2 of 0.96 for a TSS-event). By integrating the dynamic vCf into modified USLE, the strength of the dependence of daily soil loss predictions to the only other dynamic factor in the equation - daily rainfall erosivity - was reduced.

Schoettker, B.; Searle, R.; Schmidt, M.; Phinn, S.

2012-07-01

227

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 2000 NTU for the field samples and up to 8000 NTU 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 (>2000 NTU). 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

228

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

229

Event-based neural computing on an autonomous mobile platform Francesco Galluppi1, Christian Denk2, Matthias C. Meiner2, Terrence C. Stewart3, Luis A. Plana1,  

E-print Network

of the nervous system, a new class of neuromorphic devices and sensors have been developed in the last years [11]. In this paper we present an integrated robotic platform (shown in Figure 1) to explore the behavior of complex integrated platform that allows replicating principles of neural information processing in real-time. Our

Anderson, Charles H.

230

Multi-Agent Coordination with Event-based Communication Pedro V. Teixeira, Dimos V. Dimarogonas, Karl H. Johansson and Jo~ao Sousa  

E-print Network

a common issue is that of limited communication range, which is usually taken into account as a restriction by the Eu- ropean Project FeedNetBack, the Swedish Research Council, the Swedish Strategic Research such as ocean currents. The problem presented here is related to some extent to those usually posed

Dimarogonas, Dimos

231

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

232

A Diffusion Model to Estimate the Inter-arrival Time of Charged Molecules in Stochastic Event based Modeling of Complex Biological Networks  

Microsoft Academic Search

With biological experiments generating lots of empiri- cal data, the challenge is to develop a modeling paradigm that integrates structural, molecular and genetic data for a quantitative understanding of physiology and behavior of biological processes at multiple scales - starting from cell, to tissues and finally to the whole organism. The complexity of the problem motivates the use of computer

Preetam Ghosh; Samik Ghosh; Kalyan Basu; Sajal K. Das

2005-01-01

233

Characterising Seismic Hazard Input for Analysis Risk to Multi-System Infrastructures: Application to Scenario Event-Based Models and extension to Probabilistic Risk  

NASA Astrophysics Data System (ADS)

The potential human and economic cost of earthquakes to complex urban infrastructures has been demonstrated in the most emphatic manner by recent large earthquakes such as that of Haiti (February 2010), Christchurch (September 2010 and February 2011) and Tohoku (March 2011). Consideration of seismic risk for a homogenous portfolio, such as a single building typology or infrastructure, or independent analyses of separate typologies or infrastructures, are insufficient to fully characterise the potential impacts that arise from inter-connected system failure. Individual elements of each infrastructure may be adversely affected by different facets of the ground motion (e.g. short-period acceleration, long-period displacement, cumulative energy input etc.). The accuracy and efficiency of the risk analysis is dependent on the ability to characterise these multiple features of the ground motion over a spatially distributed portfolio of elements. The modelling challenges raised by this extension to multi-system analysis of risk have been a key focus of the European Project "Systemic Seismic Vulnerability and Risk Analysis for Buildings, Lifeline Networks and Infrastructures Safety Gain (SYNER-G)", and are expected to be developed further within the Global Earthquake Model (GEM). Seismic performance of a spatially distributed infrastructure during an earthquake may be assessed by means of Monte Carlo simulation, in order to incorporate the aleatory variability of the ground motion into the network analysis. Methodologies for co-simulating large numbers of spatially cross-correlated ground motion fields are appraised, and their potential impacts on a spatially distributed portfolio of mixed building typologies assessed using idealised case study scenarios from California and Europe. Potential developments to incorporate correlation and uncertainty in site amplification and geotechnical hazard are also explored. Whilst the initial application of the seismic risk analysis is directed toward seismic scenarios, this methodology can be extended to the application of probabilistic analysis of seismic hazard and risk. These applications present new challenges in terms of both the theoretical and computational implementation. They also illustrate the need for the integration of seismic hazard and risk calculations into a common software platform capable of modelling the risk analysis from end-to-end. The development of OpenQuake, the open source hazard and risk calculation platform developed as part of GEM, provides such a means of integrating state-of-the-art hazard and risk calculators. The potential direction of future developments to this software will need to take into account many of the modelling issues raised in this discussion.

Weatherill, G. A.; Silva, V.

2011-12-01

234

Open-loop Stability of Time-based vs. Event-based Switching in Locomotion Nelson Rosa Jr. and Kevin M. Lynch  

E-print Network

similar dynamics, a well- designed walking robot might also be made to brachiate. This work is a step-link dynamic wall- climbing Gibbot robot that can achieve a "foothold" at any location in the vertical plane: A step by a compass-gait biped (left) and a swing by a two-link brachiator (right) on the same slope

Hartmann, Mitra J. Z.

235

Neural network approach to the prediction of seismic events based on the VLF/LF signal monitoring of the Kuril-Kamchatka region  

NASA Astrophysics Data System (ADS)

A method of estimating of the VLF/LF signal sensitivity to seismic processes using neural network approach is proposed. To predict a seismic events we apply the error back-propagation technique, based on a three-level perceptron. Backpropagation technique involves two main stages of solving the problem: the training of the network and recognition (the prediction itself). In order to train a neural network, we first create a so-called "training set". The "teacher" specifies the correspondence between chosen input and output data. In our case a representative data base has been collected that includes both the VLF/LF data received during three-year monitoring (2005-2007) at the station in Petropavlovsk-Kamchatski and the seismicity parameters of the Kuril-Kamchatka region. At the first stage neural network established the relationship between the characteristic features of the LF signal (mean and dispersion of phase and amplitude in night-time for a few days before the seismic event) and corresponding level of correlation with the seismic event or lack of it. Teaching procedure is based on gradient descent technique, minimizing the error between the target values of outputs specified "teacher" and those that produce the neural network in the process of error minimization. The procedure of recognition (prediction) uses the neural network interpolation and extrapolation properties. Unlike the training procedure requiring many steps of iteration process the prediction requires only one passage of the recognizable signal from input to output. The final result formed at the output may be treated as a level of correlation with the seismic event or lack of it. To predict a seismic event from LF data we have chose twelve time intervals in 2003, 2005, 2006, 2007. The time intervals were lasting from 6 to 8 days including the day of seismic events of magnitude M ? 5.5. For six of the twelve time intervals the neural network has detected changes in LF signal indicating the earthquake of magnitude M ? 5.5 a few (2-3) days in a row before the earthquake, including the day itself. For the other three time intervals neural network has detected changes in a signal indicating an earthquake on the third and fourth day before the earthquake, including the prediction of the earthquake in day itself. However, changes in the signal were not detected in the first and second day before the earthquake. For the rest three time intervals correlations between the seismic events of magnitude M ? 5.5 and changes in the signal were not found.

Popova, I. V.; Rozhnoi, A. A.; Solovieva, M. S.; Levin, B. V.; Hayakawa, M.; Schwingenschuh, K.; Biagi, P. F.

2012-04-01

236

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

237

A technique for short-term warning of solar energetic particle events based on flare location, flare size, and evidence of particle escape  

NASA Astrophysics Data System (ADS)

We have developed a technique to provide short-term warnings of solar energetic proton (SEP) events that meet or exceed the Space Weather Prediction Center threshold of J (>10 MeV) = 10 pr cm-2 s-1 sr-1. The method is based on flare location, flare size, and evidence of particle acceleration/escape as parameterized by flare longitude, time-integrated soft X-ray intensity, and time-integrated intensity of type III radio emission at ˜1 MHz, respectively. In this technique, warnings are issued 10 min after the maximum of ?M2 soft X-ray flares. For the solar cycle 23 (1995-2005) data on which it was developed, the method has a probability of detection of 63% (47/75), a false alarm rate of 42% (34/81), and a median warning time of ˜55 min for the 19 events successfully predicted by our technique for which SEP event onset times were provided by Posner (2007). These measures meet or exceed verification results for competing automated SEP warning techniques but, at the present stage of space weather forecasting, fall well short of those achieved with a human (aided by techniques such as ours) making the ultimate yes/no SEP event prediction. We give some suggestions as to how our method could be improved and provide our flare and SEP event database in the auxiliary material to facilitate quantitative comparisons with techniques developed in the future.

Laurenza, M.; Cliver, E. W.; Hewitt, J.; Storini, M.; Ling, A. G.; Balch, C. C.; Kaiser, M. L.

2009-04-01

238

Combination of IL2 and IL4 inhibits glucocorticoid receptor alpha (GCR-alpha) nuclear translocation in peripheral blood mononuclear cells (PBMC) and this effect is reversed by gamma interferon  

Microsoft Academic Search

RationaleSteroid resistant asthma is associated with increased IL-2 and IL-4 gene expression. IL-2\\/IL-4 combination is known to induce corticosteroid resistance. However the mechanism for steroid resistance is unknown.

E. Goleva; R. J. Martin; D. Y. M. Leung

2004-01-01

239

Relative Damaging Ability Of Galactic Cosmic Rays Determined Using Monte Carlo Simulations Of Track Structure  

E-print Network

structures of ions that make up the galactic cosmic ray (GCR) spectrum and emphasizing biologically relevant target geometries. This research was undertaken to provide a better understanding of the damaging ability of GCR at the cellular level...

Cox, Bradley

2012-10-19

240

Lunar soil as shielding against space radiation J. Miller a,*, L. Taylor b  

E-print Network

January 2009 Keywords: Lunar soil Lunar regolith Space radiation shielding Galactic cosmic radiation (GCR to some components of the galactic cosmic radiation (GCR), using soil samples returned by the Apollo and eventually months at a time. Chronic exposure to highly ionizing ions in the galactic cosmic radiation (GCR

Perfect, Ed

241

Migration process of very low-frequency events based on a chain-reaction model1 and its application to the detection of preseismic slip for megathrust earthquakes2  

E-print Network

University, Sendai 980-8578, Japan11 3 Seismological Laboratory, California Institute of Technology, Pasadena Hasegawa2 5 6 E-mail: ariyoshi@jamstec.go.jp7 1 Earthquake and Tsunami Research Project for Disaster Prevention, Japan Agency for8 Marine-Earth Science and Technology, Yokohama 236-0001, Japan9 2 Research

Ampuero, Jean Paul

242

Galactic cosmic ray transport methods and radiation quality issues  

NASA Technical Reports Server (NTRS)

An overview of galactic cosmic ray (GCR) interaction and transport methods, as implemented in the Langley Research Center GCR transport code, is presented. Representative results for solar minimum, exo-magnetospheric GCR dose equivalents in water are presented on a component by component basis for various thicknesses of aluminum shielding. The impact of proposed changes to the currently used quality factors on exposure estimates and shielding requirements are quantified. Using the cellular track model of Katz, estimates of relative biological effectiveness (RBE) for the mixed GCR radiation fields are also made.

Townsend, L. W.; Wilson, J. W.; Cucinotta, F. A.; Shinn, J. L.

1992-01-01

243

Glucocorticoid receptors in the retina, Müller glia and the formation of Müller glia-derived progenitors.  

PubMed

Identification of the signaling pathways that influence the reprogramming of Müller glia into neurogenic retinal progenitors is key to harnessing the potential of these cells to regenerate the retina. Glucocorticoid receptor (GCR) signaling is commonly associated with anti-inflammatory responses and GCR agonists are widely used to treat inflammatory diseases of the eye, even though the cellular targets and mechanisms of action in the retina are not well understood. We find that signaling through GCR has a significant impact upon the ability of Müller glia to become proliferating Müller glia-derived progenitor cells (MGPCs). The primary amino acid sequence and pattern of GCR expression in the retina is highly conserved across vertebrate species, including chickens, mice, guinea pigs, dogs and humans. In all of these species we find GCR expressed by the Müller glia. In the chick retina, we find that GCR is expressed by progenitors in the circumferential marginal zone (CMZ) and is upregulated by Müller glia in acutely damaged retinas. Activation of GCR signaling inhibits the formation of MGPCs and antagonizes FGF2/MAPK signaling in the Müller glia. By contrast, we find that inhibition of GCR signaling stimulates the formation of proliferating MGPCs in damaged retinas, and enhances the neuronal differentiation while diminishing glial differentiation. Given the conserved expression pattern of GCR in different vertebrate retinas, we propose that the functions and mechanisms of GCR signaling are highly conserved and are mediated through the Müller glia. We conclude that GCR signaling directly inhibits the formation of MGPCs, at least in part, by interfering with FGF2/MAPK signaling. PMID:25085975

Gallina, Donika; Zelinka, Christopher; Fischer, Andy J

2014-09-01

244

Assessing access of galactic cosmic rays at Moon's orbit  

Microsoft Academic Search

Characterizing the lunar radiation environment is essential for preparing future robotic and human explorations on lunar bases. Galactic cosmic rays (GCR) represent one source of ionizing radiation at the Moon that poses a biological risk. Because GCR are charged particles, their paths are affected by the magnetic fields along their trajectories. Unlike the Earth, the Moon has no strong, shielding

Chia-Lin Huang; Harlan E. Spence; Brian T. Kress

2009-01-01

245

On the Relationship of the Energy Spectrum Indexes of the 11Year Variation of Galactic Cosmic Rays and the Interplanetary Magnetic Field Strength Fluctuations  

Microsoft Academic Search

Data of neutron super monitors and interplanetary magnetic field (IMF) have been used to find a relationship between the temporal changes of galactic cosmic rays (GCR) isotropic intensity variations energy spectrum index gamma (delta D\\/D(R) ? R-gamma , where R is the rigidity of GCR particles) and the exponent ( of the power spectral density (PSD) of the IMF's strength

M. V. Alania; K. Iskra; R. Modzelewska; M. Siluszyk

2003-01-01

246

Fretting wear behavior of superelastic nickel titanium shape memory alloy  

E-print Network

phase transition strain (5%) of NiTi, the friction force of NiTi/GCr15 stainless steel pair is smaller property than GCr15 steel. It was found that the weak ploughing was the main wear mechanism of NiTi alloy in the literatures [8­14]. Due to its unique reversible phase transition between the low-temperature martensite phase

Sun, Qing-Ping

247

INFLUENCE OF JUPITER ON COSMIC RAY INTENSITY VARIATIONS  

Microsoft Academic Search

Galactic cosmic ray (GCR) diffusion in interplanetary space depends in a certain way on the degree of regularity of the interplanetary magnetic field (IMF). The sector IMF structure is manifested in inhomogeneous GCR distribution in the heliosphere. In parallel with the usual sectors associated with solar activity, one should take into account the sectors, which are caused by the Jupiter

N. G. Skryabin; S. N. Samsonov; I. Ya

248

10Beryllium in Deep sea Sediments: Reconstructing the Intensity of the Earth's Magnetic Field and Boundary Scavenging  

Microsoft Academic Search

The cosmogenic radionuclide 10Be is produced in the upper atmosphere by spallation of nitrogen and oxygen atoms. The production rate varies as a function of the flux of galactic cosmic rays (GCR) impinging on the Earth's atmosphere. On millennial time scale the GCR flux is modulated by the shielding of the Earth's magnetic field. Therefore deep sea sediments were suggested

M. Christl; C. Strobl; P. W. Kubik; A. Mangini

2001-01-01

249

Managing Technical Risk: Understanding Private Sector  

E-print Network

research, but short of the target for venture capital investment. The ATP has clearly demonstrated its, Technology-based Projects ADADVANCEDANCED TECHNOLOGY PRTECHNOLOGY PROGRAMOGRAM NIST GCR 00-787 National Institute of Standards and Technology · Technology Administration · U.S. Department of Commerce #12;NIST GCR

250

Development of a Miniaturized Hollow-Waveguide Gas Correlation Radiometer for Trace Gas Measurements in the Martian Atmosphere  

NASA Technical Reports Server (NTRS)

We present preliminary results in the development of a miniaturized gas correlation radiometer (GCR) for column trace gas measurements in the Martian atmosphere. The GCR is designed as an orbiting instrument capable of mapping multiple trace gases and identifying active regions on the Mars surface.

Wilson, Emily L.; Georgieva, E. M.; Blalock, G. W.; Marx, C. T.; Heaps, W. S.

2012-01-01

251

Expression of Glucocorticoid Receptor ? and Its Regulation in the Bovine Endometrium: Possible Role in Cyclic Prostaglandin F2? Production  

PubMed Central

Abstract Cortisol (Cr), the most important glucocorticoid (GC), is well known to suppress uterine prostaglandin F2? (PGF) production. However, the details of the regulatory mechanisms controlling the cyclic changes in endometrial PGF production remain unclear. Here we investigated the expression of the GC receptor (GC-R?), the actions of cortisol throughout the estrous cycle and the regulatory mechanism of GC-R? in the bovine endometrium. The levels of GC-R? protein were greater at the mid-luteal stage (Days 8–12) than at the other stages. Cr more strongly suppressed PGF production at the mid-luteal stage than at the follicular stage. GC-R? expression was increased by progesterone (P4) but decreased by estradiol-17? (E2) in cultured endometrial stromal cells. The overall results suggest that ovarian steroid hormones control the cyclic changes in endometrial PGF production by regulating GC-R? expression in bovine endometrial stromal cells. PMID:23563496

KUSE, Mariko; LEE, Hwa-Yong; ACOSTA, Tomas J.; HOJO, Takuo; OKUDA, Kiyoshi

2013-01-01

252

G-Protein Complex Mutants Are Hypersensitive to Abscisic Acid Regulation of Germination  

E-print Network

opposite effects on ABA signaling during stomatal opening, GCR1 acts in concert with GPA1 and AGB1 in ABA and early seed- ling development, there is integration of signaling inputs from ABA, gibberellins (GAs

Jones, Alan M.

253

A Comparison Between Models of the Moon Radiation Environment and the Data from the RADOM Experiment Onboard the Indian Chandrayaan-1 Satellite  

NASA Astrophysics Data System (ADS)

Models of radiation environment due to Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE) on the Moon have been developed, and compared with data from the RADOM investigation onboard the ISRO CHANDRAYAAN-1 spacecraft.

de Angelis, G.; Dachev, Ts. P.; Tomov, B.; Matviichuk, Yu.; Dimitrov, P.; Spurny, F.

2010-03-01

254

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

SciTech Connect

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.

de Nolfo, Georgia 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.; von Rosenvinge, T.T.; Wiedenbeck, M.E.; Yanasak, N.E.; /NASA, Goddard /Stanford U., HEPL /Washington U., St. Louis /NASA, Headquarters/Caltech, SRL /Aerospace Corp. /Garching, Max Planck Inst., MPE /Caltech, JPL; ,

2006-11-15

255

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

256

W W W. N A T U R E . C O M / N A T U R E | 1 SUPPLEMENTARYINFORMATION doi:10.1038/nature12149  

E-print Network

Supplementary Information CGE analysis In the standard GCR assay, expression of both CAN1 and URA3 must be lost that telomere addition was not common, and URA3 and CAN1 were present at their original locations in many pif1-m analyses of 11 independent sgs1 + G4 GCR clones showed that CAN1 and URA3 were missing (data not shown

Kowalczykowski, Stephen C.

257

Galactic cosmic ray radiation levels in spacecraft on interplanetary missions  

NASA Technical Reports Server (NTRS)

Using the Langley Research Center Galactic Cosmic Ray (GCR) transport computer code (HZETRN) and the Computerized Anatomical Man (CAM) model, crew radiation levels inside manned spacecraft on interplanetary missions are estimated. These radiation-level estimates include particle fluxes, LET (Linear Energy Transfer) spectra, absorbed dose, and dose equivalent within various organs of interest in GCR protection studies. Changes in these radiation levels resulting from the use of various different types of shield materials are presented.

Shinn, J. L.; Nealy, J. E.; Townsend, L. W.; Wilson, J. W.; Wood, J.S.

1994-01-01

258

Rigidity Spectra of Primary Protons and Different Classes of Galactic Cosmic Ray Variations  

NASA Astrophysics Data System (ADS)

We study changes of proton spectra of Galactic Cosmic Ray (GCR) in free space for various minimum and near minimum epochs of 21/22, 22/23/ and 23/24 solar activity using data of different space probes. There are distinctions for positive (A>0) and negative (A<0) polarity epochs demonstrating a soft proton spectra for A<0 polarity epochs. We ascribe it to the increase of parallel and drift diffusion coefficients for the A<0 minimum epochs. We calculate rigidity spectra of long period variations of the GCR intensity using neutron monitors (NMs) and muon telescopes (MTs) data. We find that rigidity spectra of the GCR intensity variations are gradually hardening before and after reaching the maximum of the GCR intensity for all considered 21/22, 22/23/ and 23/24 minimum epochs of solar activity. In these periods an increase of the exponent nu of the Power Spectral Density (PSD) of the Interplanetary Magnetic Field (IMF) turbulence is observed confirming a validity of the quasi linear theory to describe a propagation of GCR to which NMs and MTs respond. We also study rigidity dependencies of the amplitudes of Forbush degreases and 27-day variations of the GCR intensity. We compare results of 2-D and 3-D modeling of GCR transport with the experimental data in free space (interplanetary space) and at earth orbit. We conclude that in formation of the rigidity spectrum of 11-year, 27-days and Forbush decreases measured by NMs and MTs at earth’s orbit a crucial role belongs to the character of the dependence of diffusion coefficient on the GCR particle’s rigidity, i.e. to the structure of the IMF turbulence.

Alania, Michael; Modzelewska, Renata; Siluszyk, Marek; Gil, Agnieszka; Wawrzynczak-Szaban, Anna; Iskra, Krzysztof

259

Grey Component Replacement Research, Modelling Tone And Color Reproduction  

NASA Astrophysics Data System (ADS)

Four different scanning Color Electronic Pagination System (CEPS) devices were tested to study their conventional and Grey Component Replacement/Undercolor Addition (GCR/UCA) tone and color response in the 4 color Positive Acting Offset Lithographic printing process. A common transparency input and ganged printing output was used. Inter and intra machine differences are disclosed. A new depiction of the full tone reproduction characteristics is presented for several different levels of GCR/UCA and conventional printing.

Fisch, Richard S.

1990-06-01

260

Movement Patterns of Wintering Lesser Scaup in Grand Calumet River—Indiana Harbor Canal, Indiana  

Microsoft Academic Search

Lesser scaup (Aythya affinis) winter in the Grand Calumet River—Indiana Harbor Canal (GCR-IHC) drainage into southern Lake Michigan, a polluted oasis in the highly urban and industrial corridor of northern Illinois and Indiana. The GCR-IHC is an important wintering area for lesser scaup in northwestern Indiana, especially after Lake Michigan freezes, because of the lack of other wildlife habitat in

Christine M. Custer; Thomas W. Custer; Daniel W. Sparks; Randy K. Hines; Christopher O. Kochanny

1996-01-01

261

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

262

Implementing Badhwar-O'Neill Galactic Cosmic Ray Model for the Analysis of Space Radiation Exposure  

NASA Technical Reports Server (NTRS)

For the analysis of radiation risks to astronauts and planning exploratory space missions, accurate energy spectrum of galactic cosmic radiation (GCR) is necessary. Characterization of the ionizing radiation environment is challenging because the interplanetary plasma and radiation fields are modulated by solar disturbances and the radiation doses received by astronauts in interplanetary space are likewise influenced. A model of the Badhwar-O'Neill 2011 (BO11) GCR environment, which is represented by GCR deceleration potential theta, has been derived by utilizing all of the GCR measurements from balloons, satellites, and the newer NASA Advanced Composition Explorer (ACE). In the BO11 model, the solar modulation level is derived from the mean international sunspot numbers with time-delay, which has been calibrated with actual flight instrument measurements to produce better GCR flux data fit during solar minima. GCR fluxes provided by the BO11 model were compared with various spacecraft measurements at 1 AU, and further comparisons were made for the tissue equivalent proportional counters measurements at low Earth orbits using the high-charge and energy transport (HZETRN) code and various GCR models. For the comparison of the absorbed dose and dose equivalent calculations with the measurements by Radiation Assessment Detector (RAD) at Gale crater on Mars, the intensities and energies of GCR entering the heliosphere were calculated by using the BO11 model, which accounts for time-dependent attenuation of the local interstellar spectrum of each element. The BO11 model, which has emphasized for the last 24 solar minima, showed in relatively good agreement with the RAD data for the first 200 sols, but it was resulted in to be less well during near the solar maximum of solar cycle 24 due to subtleties in the changing heliospheric conditions. By performing the error analysis of the BO11 model and the optimization in reducing overall uncertainty, the resultant BO13 model corrects the fit at solar maxima as well as being accurate at solar minima. The BO13 model is implemented to the NASA Space Cancer Risk model for the assessment of radiation risks. Overall cumulative probability distribution of solar modulation parameters represents the percentile rank of the average interplanetary GCR environment, and the probabilistic radiation risks can be assessed for various levels of GCR environment to support mission design and operational planning for future manned space exploration missions.

Kim, Myung-Hee Y.; O'Neill, Patrick M.; Slaba, Tony C.

2014-01-01

263

75 FR 41909 - Self-Regulatory Organizations; Municipal Securities Rulemaking Board; Notice of Filing of...  

Federal Register 2010, 2011, 2012, 2013

...modify the list of voluntary event-based disclosures that may be submitted...material. Additional/Voluntary Event-Based Disclosures (certain communications...reflected as additional/voluntary event-based disclosures). Amendment...

2010-07-19

264

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

265

Features of the Diffusion Processes of the Galactic Cosmic Rays around 21/22, 22/23 and 23/24 Solar Minima Epochs: 2-D Modeling and Experimental Study  

NASA Astrophysics Data System (ADS)

We study changes of perpendicular and parallel diffusion coefficients versus the different structure of the Interplanetary Magnetic Field (IMF) in ascending and descending periods of solar activity. We find periods when sub and super diffusion nature for Galactic Cosmic Rays (GCR) propagation in heliosphere distinct from each other in positive and negative polarities of solar magnetic activity for GCR particles to which neutron monitors and ground muon telescopes respond. We study different pairs of ascending and descending periods around various minima epochs (21/22, 22/23 and 23/24) comparing timelines of the exponent nu of the Power Spectral Density (PSD f (-nu) ) of the IMF and the changes of the rigidity R spectrum exponent gamma of the GCR isotropic intensity variations (deltaD(R)/D(R) R (-gamma) ). It is demonstrated that decay and creation processes of the IMF turbulence structure defer from each other for ascending and descending periods. We show that there are periods with cases of dominant sub diffusion processes over normal markovian one. We develop two-dimensional (2D) time dependent model to describe the long period variations of the GCR intensity with a new proposal to take into account a delay time among the GCR intensity changes, on one side and parameters of solar wind and solar activity (e.g. interplanetary magnetic field, tilt angle), on the other. We also attempt to take into account in modeling a more realistic role of drift during different phases of the 11-year cycle of solar activity.

Siluszyk, Marek; Alania, Michael; Iskra, Krzysztof

266

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

PubMed Central

Facile DNA sequencing became possible decades after many enzymes had been purified and characterized. Consequently, there are still “orphan” enyzmes whose activity is known but the genes that encode them 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 mis-assigned function. Bis-?-glutamylcystine reductase (GCR) is an orphan protein that was purified in 1988. This enzyme catalyzes the reduction of bis-?-glutamylcystine. ?-Glutamylcysteine (?-Glu-Cys) 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 NanoLC 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 E. coli and re-folded 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 homologs 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.

2014-01-01

267

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

268

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

269

Stratospheric polar vortex as a possible reason for temporal variations of solar activity and galactic cosmic ray effects on the lower atmosphere circulation  

NASA Astrophysics Data System (ADS)

Possible reasons for the temporal instability of long-term effects of solar activity (SA) and galactic cosmic ray (GCR) variations on the lower atmosphere circulation were studied. It was shown that the detected earlier ?60-year oscillations of the amplitude and sign of SA/GCR effects on the troposphere pressure at high and middle latitudes (Veretenenko and Ogurtsov, Adv.Space Res., 2012) are closely related to the state of a cyclonic vortex forming in the polar stratosphere. The intensity of the vortex was found to reveal a roughly 60-year periodicity affecting the evolution of the large-scale atmospheric circulation and the character of SA/GCR effects. An intensification of both Arctic anticyclones and mid-latitudinal cyclones associated with an increase of GCR fluxes at minima of the 11-year solar cycles is observed in the epochs of a strong polar vortex. In the epochs of a weak polar vortex SA/GCR effects on the development of baric systems at middle and high latitudes were found to change the sign. The results obtained provide evidence that the mechanism of solar activity and cosmic ray influences on the lower atmosphere circulation involves changes in the evolution of the stratospheric polar vortex.

Veretenenko, S.; Ogurtsov, M.

2014-12-01

270

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

271

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

272

Cycling Changes in the Amplitudes of the 27-Day Variation of the Galactic Cosmic Ray Intensity  

NASA Astrophysics Data System (ADS)

We study quasi-periodical changes in the amplitudes of the 27-day variation of the galactic cosmic ray (GCR) intensity, and the parameters of solar wind and solar activity. We have recently found quasi-periodicity of three to four Carrington rotation periods (3 - 4 CRP) in the amplitudes of the 27-day variation of the GCR intensity (Gil and Alania in J. Atmos. Solar-Terr. Phys. 73, 294, 2011). A similar recurrence is recognized in parameters of solar activity (sunspot number, solar radio flux) and solar wind (components of the interplanetary magnetic field, solar wind velocity). We believe that the 3 - 4 CRP periodicity, among other periodicities, observed in the amplitudes of the 27-day variation of the GCR intensity is caused by a specific cycling structure of the Sun's magnetic field, which may originate from the turbulent nature of the solar dynamo.

Gil, A.; Alania, M. V.

2012-06-01

273

Mean energy of response to galactic cosmic ray spectrum: IMP 8 and Climax neutron monitor  

NASA Astrophysics Data System (ADS)

Solar modulations of galactic cosmic ray (GCR) intensity contain a wealth of information about their transport in the heliosphere. To extract this information from the data one studies the dependence of the observed modulations on the mean energy of response of detectors providing data for the analyses. There is a great deal of confusion about the detector energy response to GCR spectrum in the literature. We present a preliminary report on the computations of the mean energy of response for the Climax neutron monitor (CL/NM) and IMP 8 cosmic ray nuclear composition instrument to GCR protons for 1973 1998, covering the solar cycles 21 and 22. We find that for penetrating proton channel on IMP 8 the mean energy changes by a factor of over two whereas for the neutron monitor the change is only 21%. However, the corresponding change for the computed modulation function is a factor of about 3.5.

Ahluwalia, H. S.; Lopate, C.

2008-07-01

274

The Development of Materials for Structures and Radiation Shielding in Aerospace  

NASA Technical Reports Server (NTRS)

Polymeric materials on space vehicles and high-altitude aircraft win be exposed to highly penetrating radiations. These radiations come from solar flares and galactic cosmic rays (GCR). Radiation from solar flares consists primarily of protons with energies less than 1 GeV. On the other hand, GCR consist of nuclei with energies as high as 10(exp 10) GeV. Over 90% of the nuclei in GCR are protons and alpha particles, however there is a small but significant component of particles with atomic numbers greater than ten. Particles with high atomic number (Z) and high energy interact with very high specific ionization and thus represent a serious hazard for humans and electronic equipment on a spacecraft or on high-altitude commercial aircraft (most importantly for crew members who would have long exposures). Neutrons generated by reactions with the high energy particles also represent a hazard both for humans and electronic equipment.

Kiefer, Richard L.; Orwoll, Robert A.

2001-01-01

275

Cellular track model of biological damage to mammalian cell cultures from galactic cosmic rays  

NASA Astrophysics Data System (ADS)

The assessment of biological damage from the galactic cosmic rays (GCR) is a current interest for exploratory class space missions where the highly ionizing, high-energy, high-charge ions (HZE) particles are the major concern. The relative biological effectiveness (RBE) values determined by ground-based experiments with HZE particles are well described by a parametric track theory of cell inactivation. Using the track model and a deterministic GCR transport code, the biological damage to mammalian cell cultures is considered for 1 year in free space at solar minimum for typical spacecraft shielding. Included are the effects of projectile and target fragmentation. The RBE values for the GCR spectrum which are fluence-dependent in the track model are found to be more severe than the quality factors identified by the International Commission on Radiological Protection publication 26 and seem to obey a simple scaling law with the duration period in free space.

Cucinotta, Francis A.; Katz, Robert; Wilson, John W.; Townsend, Lawrence W.; Nealy, John E.; Shinn, Judy L.

1991-02-01

276

Cosmic-Ray Modulation due to High-Speed Solar-Wind Streams of Different Sources, Speed, and Duration  

NASA Astrophysics Data System (ADS)

We study the modulation of galactic cosmic rays (GCR) due to high-speed streams (HSS) identified in the solar wind. We compare the GCR modulation due to i) streams with different speed, ii) streams of different duration, and iii) streams from different solar sources. We apply the method of superposed-epoch analysis to analyze the interplanetary plasma and field parameters during the passage of streams with distinct plasma and field characteristics. We use the plasma/field characteristics to distinguish various features of solar sources and interplanetary structures, and discuss the observed differences in the cosmic-ray response. We study the influence of speed, duration, and solar sources of the streams on the GCR modulation. We discuss the relative importance of different solar-wind parameters in the modulation process.

Kumar, Anand; Badruddin

2014-11-01

277

Cellular track model of biological damage to mammalian cell cultures from galactic cosmic rays  

NASA Technical Reports Server (NTRS)

The assessment of biological damage from the galactic cosmic rays (GCR) is a current interest for exploratory class space missions where the highly ionizing, high-energy, high-charge ions (HZE) particles are the major concern. The relative biological effectiveness (RBE) values determined by ground-based experiments with HZE particles are well described by a parametric track theory of cell inactivation. Using the track model and a deterministic GCR transport code, the biological damage to mammalian cell cultures is considered for 1 year in free space at solar minimum for typical spacecraft shielding. Included are the effects of projectile and target fragmentation. The RBE values for the GCR spectrum which are fluence-dependent in the track model are found to be more severe than the quality factors identified by the International Commission on Radiological Protection publication 26 and seem to obey a simple scaling law with the duration period in free space.

Cucinotta, Francis A.; Katz, Robert; Wilson, John W.; Townsend, Lawrence W.; Nealy, John E.; Shinn, Judy L.

1991-01-01

278

Cosmic rays in the Galaxy and their implications for VLF radio astronomy  

NASA Astrophysics Data System (ADS)

New observations of the local galactic cosmic ray (GCR) density and of the distribution of GCR nuclei in the Galaxy are described together with the results of modeling of the GCR radial profiles and the application of these results. Special attention is given to the studies of energetic cosmic rays observable with VLF radio astronomy, emphasizing the importance of higer angular resolution studies in the frequency range 1-30 MHz, with 1-2 deg resolution at 1 MHz. Examples of studies that can benefit from using such resolution include studies of H II regions, the spectral dependence of absorption and emissivity related to SNRs and giant molecular clouds, the emission and absorption related to nearby galaxies and AGN, and the determination of the detailed fine structure of interstellar absorption. In addition, the VLF radio astronomy can be used for studies of all types of energetic particle populations in different galaxies.

Webber, W. R.

279

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

280

Revised Production Rates for Na-22 and Mn-54 in Meteorites Using Cross Sections Measured for Neutron-induced Reactions  

NASA Technical Reports Server (NTRS)

The interactions of galactic cosmic rays (GCR) with extraterrestrial bodies produce small amounts of radionuclides and stable isotopes. The production rates of many relatively short-lived radionuclides, including 2.6-year Na-22 and 312-day Mn-54, have been measured in several meteorites collected very soon after they fell. Theoretical models used to calculate production rates for comparison with the measured values rely on input data containing good cross section measurements for all relevant reactions. Most GCR particles are protons, but secondary neutrons make most cosmogenic nuclides. Calculated production rates using only cross sections for proton-induced reactions do not agree well with measurements. One possible explanation is that the contribution to the production rate from reactions initiated by secondary neutrons produced in primary GCR interactions should be included explicitly. This, however, is difficult to do because so few of the relevant cross sections for neutron-induced reactions have been measured.

Sisterson, J. M.; Kim, K. J.; Reedy, R. C.

2004-01-01

281

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

282

Relative contributions of galactic cosmic rays and lunar proton "albedo" to dose and dose rates near the Moon  

NASA Astrophysics Data System (ADS)

use validated radiation transport models of the Cosmic Ray Telescope for the Effects of Radiation instrument and its response to both primary galactic cosmic rays (GCR) and secondary radiation, including lunar protons released through nuclear evaporation, to estimate their relative contributions to total dose rate in silicon (372 ?Gy/d) and dose equivalent rate at the skin (2.88 mSv/d). Near the Moon, we show that GCR accounts for ~91.4% of the total absorbed dose, with GCR protons accounting for ~42.8%, GCR alpha particles for ~18.5%, and GCR heavy ions for ~30.1%. The remaining ~8.6% of the dose at Lunar Reconnaissance Orbiter altitudes (~50 km) arises from secondary lunar species, primarily "albedo" protons (3.1%) and electrons (2.2%). Other lunar nuclear evaporation species contributing to the dose rate are positrons (1.5%), gammas (1.1%), and neutrons (0.7%). Relative contributions of these same species to the total dose equivalent rate in skin, a quantity of more direct biological relevance, favor those with comparatively high quality factors. Consequently, the primary GCR heavy ion components dominate the estimated effective skin dose. Finally, we note that when considering the lunar radiation environment, although the Moon blocks approximately half of the sky, thus essentially halving the absorbed dose rate near the Moon relative to deep space, the secondary radiation created by the presence of the Moon adds back a small, but measurable, absorbed dose (~8%) that can and should be now accounted for quantitatively in radiation risk assessments at the Moon and other similar exploration targets.

Spence, Harlan E.; Golightly, Michael J.; Joyce, Colin J.; Looper, Mark D.; Schwadron, Nathan A.; Smith, Sonya S.; Townsend, Lawrence W.; Wilson, Jody; Zeitlin, Cary

2013-11-01

283

A membrane glucocorticoid receptor mediates the rapid/non-genomic actions of glucocorticoids in mammalian skeletal muscle fibres.  

PubMed

Glucocorticoids (GCs) are steroid hormones released from the adrenal gland in response to stress. They are also some of the most potent anti-inflammatory and immunosuppressive drugs currently in clinical use. They exert most of their physiological and pharmacological actions through the classical/genomic pathway. However, they also have rapid/non-genomic actions whose physiological and pharmacological functions are still poorly understood. Therefore, the primary aim of this study was to investigate the rapid/non-genomic effects of two widely prescribed glucocorticoids, beclomethasone dipropionate (BDP) and prednisolone acetate (PDNA), on force production in isolated, intact, mouse skeletal muscle fibre bundles. The results show that the effects of both GCs on maximum isometric force (Po) were fibre-type dependent. Thus, they increased Po in the slow-twitch fibre bundles without significantly affecting that of the fast-twitch fibre bundles. The increase in Po occurred within 10 min and was insensitive to the transcriptional inhibitor actinomycin D. Also, it was maximal at ?250 nM and was blocked by the glucocorticoid receptor (GCR) inhibitor RU486 and a monoclonal anti-GCR, suggesting that it was mediated by a membrane (m) GCR. Both muscle fibre types expressed a cytosolic GCR. However, a mGCR was present only in the slow-twitch fibres. The receptor was more abundant in oxidative than in glycolytic fibres and was confined mainly to the periphery of the fibres where it co-localised with laminin. From these findings we conclude that the rapid/non-genomic actions of GCs are mediated by a mGCR and that they are physiologically/therapeutically beneficial, especially in slow-twitch muscle fibres. PMID:23878367

Pérez, María Hernández-Alcalá; Cormack, Jonathan; Mallinson, David; Mutungi, Gabriel

2013-10-15

284

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

285

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

286

Issues in deep space radiation protection  

NASA Technical Reports Server (NTRS)

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 the thickness range for space applications. Methods for optimization of spacecraft shielding and the associated role of materials selection are discussed. One material which may prove to be an important radiation protection material is hydrogenated carbon nanofibers. c 2001. Elsevier Science Ltd. All rights reserved.

Wilson, J. W.; Shinn, J. L.; Tripathi, R. K.; Singleterry, R. C.; Clowdsley, M. S.; Thibeault, S. A.; Cheatwood, F. M.; Schimmerling, W.; Cucinotta, F. A.; Badhwar, G. D.; Noor, A. K.; Kim, M. Y.; Badavi, F. F.; Heinbockel, J. H.; Miller, J.; Zeitlin, C.; Heilbronn, L.

2001-01-01

287

An overview of the physics of the Earth's radiation environment , L. Desorgher2  

E-print Network

An overview of the physics of the Earth's radiation environment R. Vainio1 , L. Desorgher2 , E. Fl, University of Oulu, Finland 1 Introduction The Earth's radiation environment consists of three major components: the galactic cosmic rays (GCR), the solar energetic particles (SEPs) or solar cosmic rays (SCR

Usoskin, Ilya G.

288

Mechanistical studies on the formation and destruction of carbon monoxide (CO), carbon dioxide (CO2), and carbon trioxide (CO3)  

E-print Network

from both the solar wind and Galactic Cosmic Radiation (GCR); the flux of the solar wind decreases have also been positively identified on the dwarf planet Pluto.12 These ices are subject to radiation solar system is considered. According to ref. 13, the solar radiation consists of solar photons (f E 2

Kaiser, Ralf I.

289

RADIATION RESEARCH 156, 612617 (2001) 0033-7587/01 $5.00  

E-print Network

(high-LET) galactic cosmic rays (GCR) contribute a significant component of the radiation risk in free612 RADIATION RESEARCH 156, 612­617 (2001) 0033-7587/01 $5.00 2001 by Radiation Research Society on Radiation Risks in a Mars Mission D. J. Brenner1 and C. D. Elliston Center for Radiological Research

Brenner, David Jonathan

290

Carbon Nanotube Polymer Composites While there are limitless  

E-print Network

heavy atoms that are known to be part of Galactic Cosmic Radiation (GCR). Such radiation is encountered for these materials, we are interested in radiation shielding and radiation resistant materials for use in the space-5). Three different in situ polymerization/sonication methods, heat, light and gamma radiation, were used

Harmon, Julie P.

291

First detection of the silylgermylene (H3SiGeH) and D4-silylgermylene (D3SiGeD) molecules in low temperature silanegermane ices  

E-print Network

of tempera- tures from 93 to 393 K and ionizing radiation from the Solar Wind and the Galactic Cosmic August 2012 In final form 7 October 2012 Available online 16 October 2012 Keywords: Ionizing radiation Radiation (GCR); these properties make HBTs important building blocks in space electronics design, since

Kaiser, Ralf I.

292

S isotope values of dissolved sulfate (SO4  

E-print Network

of groundwater beneath the (GCR) property, a battery recycling facility in east Tampa, Florida, varies more than with sulfuric acid (H2SO4) and lead (Pb), as a result of battery manu- facturing or recycling, is a common of contamination, despite a global increase in battery recycling (Tsoulfas and others 2002; Roberts 2003

Pichler, Thomas

293

January 2007 Economic Impact of ATP's  

E-print Network

, and services from ATP supported projects) · Impacts (long term impacts on U.S. industry, society, and economyJanuary 2007 Economic Impact of ATP's Contributions to DNA Diagnostics Technologies GCR 06 Assessment Office (EAO) has performed rigorous and multifaceted evaluations to assess the impact

294

Increased genome instability and telomere length in the elg1-deficient Saccharomyces cerevisiae mutant are regulated by S-phase checkpoints.  

PubMed

Gross chromosomal rearrangements (GCRs) are frequently observed in cancer cells. Abnormalities in different DNA metabolism including DNA replication, cell cycle checkpoints, chromatin remodeling, telomere maintenance, and DNA recombination and repair cause GCRs in Saccharomyces cerevisiae. Recently, we used genome-wide screening to identify several genes the deletion of which increases GCRs in S. cerevisiae. Elg1, which was discovered during this screening, functions in DNA replication by participating in an alternative replication factor complex. Here we further characterize the GCR suppression mechanisms observed in the elg1Delta mutant strain in conjunction with the telomere maintenance role of Elg1. The elg1Delta mutation enhanced spontaneous DNA damage and resulted in GCR formation. However, DNA damage due to inactivation of Elg1 activates the intra-S checkpoints, which suppress further GCR formation. The intra-S checkpoints activated by the elg1Delta mutation also suppress GCR formation in strains defective in the DNA replication checkpoint. Lastly, the elg1Delta mutation increases telomere size independently of other previously known telomere maintenance proteins such as the telomerase inhibitor Pif1 or the telomere size regulator Rif1. The increase in telomere length caused by the elg1Delta mutation was suppressed by a defect in the DNA replication checkpoint, which suggests that DNA replication surveillance by Dpb11-Mec1/Tel1-Dun1 also has an important role in telomere length regulation. PMID:15590829

Banerjee, Soma; Myung, Kyungjae

2004-12-01

295

Effects of glucocorticoids on lymphocyte activation in patients with steroid-sensitive and steroid-resistant asthma  

Microsoft Academic Search

BACKGROUND: Glucocorticoids are important medications used to control the airway inflammation associated with asthma. Synthetic glucocorticoids vary in their binding affinity for the glucocorticoid receptor (GCR). METHODS: We compared hydrocortisone, beclomethasone dipropionate, triamcinolone acetonide, flunisolide, and budesonide with regard to their capacity to inhibit phytohemagglutinin-induced peripheral blood mononuclear cell proliferation from six patients with steroid-sensitive asthma and seven patients with

Joseph D. Spahn; Lawrence P. Landwehr; Sai Nimmagadda; Wendy Surs; Donald Y. M. Leung

1996-01-01

296

p.4--College Projects/Academic p.12--Intercultural  

E-print Network

Contents p.2--GCR p.4--College Projects/Academic p.12--Intercultural p.16--Alumni P.17--Social p.25--10th Anniversary P.29--Features p.35--Off the Hill p.4S--Clubs and Societies p.47--Funnies A word type of music you chose, but preferably Beyonc�. Clubs and Socs-wise, we have given the Badminton team

Wirosoetisno, Djoko

297

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

298

Sudden cosmic ray decreases: No change of global cloud cover J. Calogovic,1  

E-print Network

Click Here for Full Article Sudden cosmic ray decreases: No change of global cloud cover J; revised 22 December 2009; accepted 4 January 2010; published 3 February 2010. [1] Currently a cosmic ray that galactic cosmic rays (GCR) intruding the Earth's atmosphere influence cloud cover. If correct it would have

Wehrli, Bernhard

299

The production of cosmogenic nuclides in stony meteoroids by galactic cosmic ray particles  

Microsoft Academic Search

We present a purely physical model for the calculation of depth- and size-dependent production rates of cosmogenic nuclides by galactic cosmic ray particles. Besides the spectra of primary and secondary particles and the excitation functions of the underlying nuclear reactions the model is based on only one free parameter, the integral number of GCR particles in the meteoroid orbits. We

Ingo Leya; Hans-Jürgen Lange; Sonja Neumann; Rainer Wieler; Rolf Michel

2000-01-01

300

The Influence of Different Helio-geophysical Factors On Long-periodical and Abrupt Climate Change  

Microsoft Academic Search

The Earth's climate experiences a continuous influence of several helio-geophysical factors associated with long-term variations in solar activity and changes in the mag- nitude and configuration of the geomagnetic field. As shown by recent investigations, galactic cosmic rays (GCR) exert a considerable effect on physical and chemical pro- cesses in the troposphere, including development of cloudiness. More intense (less intense)

O. Raspopov; V. Dergachev; N.-A. Morner; T. Kolstrom; O. Shumilov; E. Goos'kova

2002-01-01

301

Designing a Complex Fragmentation Block for Simulating the Galactic Environment by Using a Single Accelerator Beam in PHITS (Practicle and Heavy Ion Transport Code System)  

E-print Network

the linear energy transfer (LET) spectrum found in the GCR. The purpose of this thesis research is to use a Monte Carlo transport code to study the fragmentation of a combined iron and proton beam source using a multi-depth moderator block to reproduce...

Chen, Gary

2011-10-21

302

A comparison of total reaction cross section models used in FLUKA, GEANT4 and PHITS  

Microsoft Academic Search

Understanding the interactions and propagations of high energy protons and heavy ions are essential when trying to estimate the biological effects of Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE) on personnel on interplanetary missions, and when preparing the construction of a lunar base. To be able to calculate the secondary particles, including neutrons, and to estimate shielding properties

L. Sihver; M. Lantz; T. T. Bohlen; A. Mairani; A. F. Cerutti; A. Ferrari

2012-01-01

303

Comparison of the transport codes HZETRN, HETC and FLUKA for galactic cosmic rays  

Microsoft Academic Search

The HZETRN deterministic radiation code is one of several tools developed to analyze the effects of harmful galactic cosmic rays (GCR) and solar particle events on mission planning and shielding for astronauts 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

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

2011-01-01

304

Study of spatial and temporal structure of long-term effects of solar activity and cosmic ray variations on the lower atmosphere circulation  

NASA Astrophysics Data System (ADS)

The spatial and temporal structure of the effects of solar activity (SA) and galactic cosmic ray (GCR) flux variations on the lower atmosphere circulation has been studied based on NCEP/NCAR reanalysis archive for 1948-2006 and MSLP (Climatic Research Unit, UK) data for 1873-2000. It has been shown that the GCR effects on pressure variations are characterized by a strong latitudinal and regional dependence, which is determined by specific features of the tropospheric circulation in the studied regions. The distribution of the correlation coefficients for mean yearly values of atmospheric pressure with the GCR flux intensity is closely related to the position of the main climatological fronts. The periodic (˜60 years) changes in the correlation sign of the pressure at high and middle latitudes with Wolf numbers have been revealed. It has been suggested that the changes of the sign of SA/GCR effects on atmospheric pressure are caused by the changes of the macrocirculation epochs, which, in turn, may be related to large-scale processes on the Sun.

Veretenenko, S. V.; Ogurtsov, M. G.

2012-09-01

305

GENERALIZED TRANSDUCTION IN CAULOBACTER CRESCENTUS  

Microsoft Academic Search

Two closely related bacteriophage, $Cr30 and GCr35, are the first bacterio- phage shown to mediate generalized transductim in Caulobacter crescentus. Unlike most other transducing phage, they are virulent and do not form any sort of lysogenic relationship with their host. Howevcr, they are rather ineffi- cient at adsorption, so that transductants have a good chance of survival. The phage particles

BERT ELY; REID C. JOHNSON

306

Expanding the frontiers of  

E-print Network

for these aspects of student life? In offering a college system we provide the context, but as PVC for Students I with the student body itself, through the college JCR and GCR committees and the two students' unions funding arrangements present us with a new consumerism amongst students and, as a university, we need

307

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

308

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...

309

Solar Phys (2010) 261: 353359 DOI 10.1007/s11207-009-9497-4  

E-print Network

is produced not by galactic cosmic rays (GCR) but mostly by particles of solar or magnetospheric origin (e variability of the 14 C production rate. Solar energetic particles (SEP) can also produce some additionalSolar Phys (2010) 261: 353­359 DOI 10.1007/s11207-009-9497-4 Critical Comment on the Article by R

Usoskin, Ilya G.

310

The proposed connection between clouds and cosmic rays: Cloud  

E-print Network

cosmic rays are very energetic particles from outside the solar system which penetrate to the bottom by the magnetic field of the Sun via the solar wind. Because GCR are ionized particles, they are deflected particles can 2 #12; reach the Earth; at solar minima the Sun's magnetic field is weaker and the particle

311

Cancer risk from exposure to galactic cosmic rays: implications for space exploration by human beings  

Microsoft Academic Search

must be balanced with the cost, safety, and ethical concerns when deciding acceptable risks for astronauts. The main health concerns are exposure to galactic cosmic rays (GCR) and solar proton events, which lead to substantial, but poorly understood, risks of carcinogenesis and degenerative disease. 2,3 Spacefl ights in low Earth orbit, such as missions on a space shuttle and at

Marco Durante

2006-01-01

312

Geant4 Monte Carlo Simulations of the Galactic Cosmic Ray Radiation Environment On-Board the International Space Station\\/Columbus  

Microsoft Academic Search

A characterization of the Galactic cosmic ray (GCR) induced radiation environment on-board Columbus and the International Space Station (ISS) has been carried out using the Geant4 Monte Carlo particle transport toolkit and detailed geometry models of Columbus and ISS. Dose and dose equivalent rates, as well as penetrating particle spectra are presented. Simulation results indicate that the major part of

Tore Ersmark; Per Carlson; Eamonn Daly; Christer Fuglesang; Irena Gudowska; Bengt Lund-Jensen; Petteri Nieminen; Mark Pearce; Giovanni Santin

2007-01-01

313

Radiation Dose Analysis of Galactic Cosmic Ray in Low Earth Orbit/Near Equatorial Orbit  

NASA Astrophysics Data System (ADS)

Space environment contained harmful radiation that posed risk to spacecraft orbiting the Earth. In this paper, we looked into radiation doses caused by galactic cosmic ray (GCR) towards satellites orbiting in low earth orbit (LEO) near Earth's equator (NEqO) and compared them with doses caused by solar energetic particles (SEP) and trapped particles to determine the damage level of GCR. The radiation doses included linear energy transfer (LET) and nonionizing energy loss (NIEL) through a 1mm gallium arsenide (GaAs) planar geometry by using Space Environment Information System (SPENVIS) method. The orbital data followed Malaysian Razaksat satellite at 685km altitude and 9° inclination during selected solar minimum and solar maximum from solar cycles 21 to 24. We found that trapped particles gave the highest LET and no SEP was detected in SPENVIS. The LET values tend to be higher during solar minimum for trapped particles and GCR, corresponding to their anti-correlated fluxes with the solar activity. However, the NIEL values for GCR in solar cycle 23 did not follow the anti-correlation pattern.

Suparta, W.; Zulkeple, S. K.

2014-10-01

314

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

315

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

316

Heliospheric modulation of galactic cosmic rays during grand solar minima: Past and future variations  

E-print Network

magnetic flux and the heliospheric magnetic flux (HMF) have varied approximately in phase with the sunspot cycle. On longer timescales the HMF has been evaluated using geomagnetic activity as a proxy indicator [Lockwood et al., 2009; Lockwood and Owens, 2011]. The HMF modulates the galactic cosmic ray (GCR) flux

Lockwood, Mike

317

Charged and Neutral Particle Interactions on Aerospace Materials  

Microsoft Academic Search

Various candidate aircraft and spacecraft materials were analyzed and compared in a neutron environment using the Monte Carlo N-Particle (MCNP) transport code and in Galactic Cosmic Ray (GCR) and Trapped environments using the HZETRN code. These candidate materials are being used in aerospace vehicles, have been tested in particle beams, or seemed reasonable to analyze in this manner before deciding

R. C. Jr. Singleterry; Sheila A. Thibeault; Richard Wilkins; Harold Huff

2002-01-01

318

Galactic Cosmic Rays measured by UVS on Voyager 1 and the end of the modulation: Is the upwind heliopause a collapsed charge-exchange layer?  

E-print Network

The detectors of the UltraViolet Spectrographs (UVS) on Voyager 1/2 are recording a background that was earlier assigned to disintegrations in the RTG. We show that it arises instead from Galactic Cosmic Rays (GCRs). We show the 1992-2013 GCR flux measured by UVS on V1 and, by comparing with data from the GCR dedicated detectors, we estimate the energy range responsible for this UVS signal, around 300 MeV, and the response of UVS to the GCR anisotropy. After the abrupt jumps of May and August 2012 the count rate has been fluctuating only slightly around a constant value, but comparing with data from the LECP and the CRS instruments shows that those small variations are only responses to a varying anisotropy and not to a flux change. Taking advantage of the similarity in energy range to one of the products of the CRS instrument suite, we use the ratio between the two independent signals as a proxy for the temporal evolution of the GCR spectral slope around the 300 MeV range. We show that this slope has remaine...

Lallement, R; Quemerais, E; Sandel, B R

2014-01-01

319

Comparison of CREME (cosmic-ray effects on microelectronics) model LET (linear energy transfer) spaceflight dosimetry data  

SciTech Connect

The galactic cosmic radiation (GCR) component of space radiation is the dominant cause of single-event phenomena in microelectronic circuits when Earth's magnetic shielding is low. Spaceflights outside the magnetosphere and in high inclination orbits are examples of such circumstances. In high-inclination orbits, low-energy (high LET) particles are transmitted through the field only at extreme latitudes, but can dominate the orbit-averaged dose. GCR is an important part of the radiation dose to astronauts under the same conditions. As a test of the CREME environmental model and particle transport codes used to estimate single event upsets, we have compiled existing measurements of HZE doses were compiled where GCR is expected to be important: Apollo 16 and 17, Skylab, Apollo Soyuz Test Project, and Kosmos 782. The LET spectra, due to direct ionization from GCR, for each of these missions has been estimated. The resulting comparisons with data validate the CREME model predictions of high-LET galactic cosmic-ray fluxes to within a factor of two. Some systematic differences between the model and data are identified.

Letaw, J.R.; Adams, J.H.

1986-07-15

320

Predicting space climate change L. Barnard,1  

E-print Network

modern operational systems, such as spacecraft, power distribution grids and aircraft [Hapgood, 2011]. Mc of the Grand Solar Maximum (GSM) that has persisted throughout the space age, during which the largestfluence Solar Energetic Particle (SEP) events have been rare and Galactic Cosmic Ray (GCR) fluxes have been

Wehrli, Bernhard

321

How Safe Is Safe Enough? Radiation Risk for a Human Mission to Mars  

PubMed Central

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

322

Three dimensional modeling with the changeable solar wind velocity and expected spatial distributions of the gradients and anisotropy of Galactic Cosmic Rays  

Microsoft Academic Search

We develop a three dimensional (3-D) model of the recurrent decreases (Forbush effect) of GCR including the changeable solar wind velocity. We found the solution of the equation divB = 0 of the Interplanetary Magnetic field (IMF) B for the azimuthally dependence of the radial component of the solar wind velocity. In this case there exist all three components -

Michael Alania; Renata Modzelewska; Anna Wawrzynczak-Szaban

2008-01-01

323

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

324

May 2005 Halo CMEs and Galactic Cosmic Ray Flux Changes at Earth's Orbit  

NASA Astrophysics Data System (ADS)

The pressure corrected hourly data from the global network of cosmic ray detectors, measurements of the interplanetary magnetic field (IMF) intensity ( B) at Earth's orbit and its components B x , B y , B z (in the geocentric solar ecliptic coordinates) are used to conduct a comprehensive study of the galactic cosmic ray (GCR) intensity fluctuations caused by the halo coronal mass ejection of 13 May 2005. Distinct differences exist in GCR timelines recorded by neutron monitors (NMs) and multidirectional muon telescopes (MTs), the latter respond to the high rigidity portion of the GCR differential rigidity spectrum. The Forbush decrease (FD) onset in MTs is delayed (˜5 h) with respect to the onset of a geomagnetic storm sudden commencement (SSC) and a large pre-increase is present in MT data before, during, and after the SSC onset, of unknown origin. The rigidity spectrum, for a range of GCR rigidities (?200 GV), is a power law in rigidity (R) with a negative exponent ( ?=-1.05) at GCR minimum intensity, leading us to infer that the quasi-linear theory of modulation is inconsistent with observations at high rigidities (>1 GV); the results support the force field theory of modulation. At present, we do not have a comprehensive model for the FD explaining quantitatively all the observational features but we present a preliminary model listing physical processes that may contribute to a FD timeline. We explored the connections between different phases of the FD and the power spectra of IMF components but did not find a sustained relationship.

Ahluwalia, H. S.; Alania, M. V.; Wawrzynczak, A.; Ygbuhay, R. C.; Fikani, M. M.

2014-05-01

325

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

326

Physics of the Isotopic Dependence of Galactic Cosmic Ray Fluence Behind Shielding  

NASA Technical Reports Server (NTRS)

For over 25 years, NASA has supported the development of space radiation transport models for shielding applications. The NASA space radiation transport model now predicts dose and dose equivalent in Earth and Mars orbit to an accuracy of plus or minus 20%. However, because larger errors may occur in particle fluence predictions, there is interest in further assessments and improvements in NASA's space radiation transport model. In this paper, we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR) and the isotopic dependence of nuclear fragmentation cross-sections on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. Using NASA's quantum multiple-scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, we study the effect of the isotopic dependence of the primary GCR composition and secondary nuclei on shielding calculations. The QMSFRG is shown to accurately describe the iso-spin dependence of nuclear fragmentation. The principal finding of this study is that large errors (plus or minus 100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotope grid (approximately 170 ions) to ones that use a reduced isotope grid, for example the 59 ion-grid used in the HZETRN code in the past, however less significant errors (less than 20%) occur in the elemental-fluence spectra. Because a complete isotope grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies.

Cucinotta, Francis A.; Saganti, Premkumar B.; Hu, Xiao-Dong; Kim, Myung-Hee Y.; Cleghorn, Timothy F.; Wilson, John W.; Tripathi, Ram K.; Zeitlin, Cary J.

2003-01-01

327

Low expression of glucocorticoid receptor alpha isoform in adult immune thrombocytopenia correlates with glucocorticoid resistance.  

PubMed

The expression of glucocorticoid receptor (GR) isoforms has been linked to glucocorticoid (GC) resistance in various diseases treated with GC. However, existing data are conflicting in these diseases, and little information is available regarding immune thrombocytopenia (ITP). To further investigate the role of GR isoforms in GC resistance in adult ITP patients, we measured the mRNA expression of GR isoforms (GR?, GR?, GR?, GRp) in peripheral blood mononuclear cells (PBMC) from 54 newly diagnosed ITP patients, including GC-sensitive (GCS) and GC-resistant (GCR) patients and 35 healthy volunteers. The GR? and GR? proteins in PBMC, nuclear factor-?B (NF-?B), and activator protein-1 (AP-1) in the nucleus were detected by Western blotting. Compared to normal subjects, both GR? and GR? mRNAs were significantly increased in ITP patients (p?GCR patients, the expressions of GR? mRNA and GR? protein were significantly higher in GCS patients (p?GCR patients and the GR? protein could not be detected. Compared to GCS group, the expression of p65/NF-?B was significantly higher in the GCR group (p?GCR patients. In summary, GC resistance in adult ITP patients is associated with a reduced expression of GR?, which may be related with increased NF-?B. GR? was very low and may not be involved in GC resistance in adult ITP, warranting further exploration. PMID:23435844

Ma, Liangliang; Fang, Meiyun; Liang, Yan; Xiang, Yang; Jia, Zhilin; Sun, Xiuli; Wang, Yi; Qin, Jixia

2013-07-01

328

Radiation effects in space: The Clementine I mission  

SciTech Connect

The space radiation environment for the CLEMENTINE I mission was investigated using a new calculational model, CHIME, which includes the effects of galactic cosmic rays (GCR), anomalous component (AC) species and solar energetic particle (SEP) events and their variations as a function of time. Unlike most previous radiation environment models, CHIME is based upon physical theory and is {open_quotes}calibrated{close_quotes} with energetic particle measurements made over the last two decades. Thus, CHIME provides an advance in the accuracy of estimating the interplanetary radiation environment. Using this model we have calculated particle energy spectra, fluences and linear energy transfer (LET) spectra for all three major components of the CLEMENTINE I mission during 1994: (1) the spacecraft in lunar orbit, (2) the spacecraft during asteroid flyby, and (3) the interstate adapter USA in Earth orbit. Our investigations indicate that during 1994 the level of solar modulation, which dominates the variation in the GCR and AC flux as a function of time, will be decreasing toward solar minimum levels. Consequently the GCR and AC flux will be increasing during Y, the year and, potentially, will rise to levels seen during previous solar minimums. The estimated radiation environment also indicates that the AC will dominate the energetic particle spectra for energies below 30-50 MeV/nucleon, while the GCR have a peak flux at {approximately}300 MeV/nucleon and maintain a relatively high flux level up to >1000 MeV/nucleon. The AC significantly enhances the integrated flux for LET in the range 1 to 10 MeV/(mg/cm{sup 2}), but due to the steep energy spectra of the AC a relatively small amount of material ({approximately}50 mils of Al) can effectively shield against this component. The GCR are seen to be highly penetrating and require massive amounts of shielding before there is any appreciable decrease in the LET flux.

Guzik, T. G.; Clayton, E.; Wefel, J. P.

1994-12-20

329

Large Galactic Cosmic Ray Anisotropies in the Heliosheath  

NASA Astrophysics Data System (ADS)

The angular distribution of galactic cosmic ray (GCR) intensities had been observed to be nearly isotropic throughout the space age, with even the largest anisotropies falling well short of 1%. Voyager 1, after the initial GCR intensity enhancement in May 2012 and upon sustainably entering a region depleted of hot plasma on 25 August 2012 (Burlaga et al. 2013; Krimigis et al. 2013; Stone et al. 2013; Webber & McDonald 2013), has uncovered a new regime where large GCR anisotropies prevail. We recently reported on the largest GCR anisotropies observed (Krimigis et al., 2013; Hill et al., 2013), with the second order anisotropy of >200 MeV GCRs reaching ~3.5%. We developed a new technique to extract bi-directional intensities from a double-ended particle telescope that has asymmetric viewing geometry (i.e., the geometric factor for particle detection with one end is unequal to the geometric factor of the other end). Applying this technique we report here on the variation of GCR anisotropies at Voyager 1 and 2 in the depletion region, in the hot heliosheath, and upstream of the termination shock. Burlaga, L.F. et al, 2013, Science 341, 147-150, DOI: 10.1126/science.1235451. Hill, M.E. et al, 2013, presented at the 12th Ann. Inter. Astrophys. Conf., Myrtle Beach, SC, 15-19 April 2013. Krimigis, S.M. et al., 2013, Science 341, 144-147, DOI: 10.1126/science.1235721. Stone, E.C. et al., 2013, Science 341, 150-153, DOI: 10.1126/science.1236408. Webber & McDonald, 2013, Geophys. Res. Let. 40, 1665-1668, DOI: 10.1002/grl.50383.

Hill, M. E.; Decker, R. B.; Hamilton, D. C.; Brown, L. E.; Krimigis, S. M.; Roelof, E. C.

2013-12-01

330

On manifestation of the solar wind turbulence in fluctuations of the galactic cosmic ray intensity  

NASA Astrophysics Data System (ADS)

We study a relationship between the interplanetary magnetic field (IMF) and the solar wind speed (SWS) turbulence measured in the interplanetary space (in situ) and the galactic cosmic ray (GCR) intensity fluctuations measured by neutron monitors (at earth surface) for different time scales of ranges 5 - 60 minutes and 1 - 24 hours. We calculate the Probability Distribution Functions (PDF) of differences ?B?, ?V ? , and ?I? of the time series B(ti) of the IMF strength , V (ti) of the SWS, and I(ti) of the GCR intensity, respectively, as ?B? = B(t + ?) - B(t), ?V ? = V (t + ?) - V (t) and ?I? = I(t + ?) - I(t) over varying time scales ?. Then, we find correlation coefficients among them and characteristic time scale ?0 for which (? > ?0) the asymmetry (skewness) and kurtosis of PDFs are minimum, and in good approximation PDFs have Gaussian distributions. We show that the asymmetry and inhomogeneities of the IMF and solar wind turbulence generally are manifested for time scale ? < 1 day, while for the GCR fluctuations for ? ?0, and PDF has a Gaussian distribution, the IMF turbulence is characterized by the power spectral density (PSD), with parameters p and ? (PSD = Pf-? , where P is power and f is a frequency). In this case diffusion of GCR particles could be described by the quasi linear theory (QLT), and diffusion coefficient K is proportional to the rigidity R, as K ~ R2-?; correspondingly, the exponent ? of the rigidity R spectrum (?D(R)-D(R) ? R-?) of the GCR intensity variations (e.g. of Forbush decrease) of the energy to which neutron monitors and muon telescopes (for rigidity > 5 - 10 GV) respond, is determined by the exponent ? of PSD of the IMF turbulence.

Alania, Michael V.; Modzelewska, Renata; Wawrzynczak, Anna

2010-05-01

331

Stochastic differences of the solar cycles according to monitoring cosmogenic radionuclides in fresh-fallen meteorites  

NASA Astrophysics Data System (ADS)

Cosmogenic radionuclides with different T_1/2, which are observed in meteorites, are natural detectors of cosmic rays along the meteorite orbits during ~1.5 T_1/2 of the radionuclides before the meteorite fall onto the Earth. The investigation of radionuclides with different T_1/2 in the chondrites with various dates of fall, which have various extension and inclination of orbits, provides us with such long sequences of homogeneous data on variation of the GCR intensity and integral gradients (E>100 MeV) in the 3D heliosphere [1]. The long sequences of homogeneous data on the GCR intensity in the stratosphere are used for evaluation of the gradients [2]. Nowadays, such a sequence of certain homogeneous data on the GCR intensity and gradients in the inner heliosphere covers ~5 solar cycles [3]. This smoothes, to a considerable extent, both the temporal and spatial GCR variations revealing the most important general regularities, namely: the dependence of the GCR gradients in the inner heliosphere (at 2-4 AU from the Sun) on the phase of the solar cycles and the constancy of the mechanism of the solar modulation of GCRs, at least over the last ~1 Ma. The most striking effect - which due to the monitoring became evident - is a stochastic difference of the solar cycles in addition to their determination by the solar activity. A rigorous analysis of correlations between the distribution and variations of GCRs and various indexes of the solar activity, as well as the strength of interplanetary magnetic fields and the title of the heliospheric current sheet in the three-dimensional heliosphere, have been carry out. As a whole, it testifies to the approximately positive correlations of all the parameters. However, the analysis has revealed some dependence of the depth of GCR modulation in the heliosphere on the character of the solar magnetic fields inversion during the maximum phases of the solar cycles, namely, on N-S asymmetry of emergence of active areas, on difference of their beginning and developing, on different lasting of the inversion periods, etc. For instance, a combined operation of the effects resulted in the deepest minimum of the GCR intensity in stratosphere in 1990-1991 and the highest GCR gradients for the 22nd solar cycle. Some peculiarities of the 23 and 24 solar cycles are considered due to study of radionuclides in the recently fallen Kosice and Chelyabinsk chondrites. The observed features of the GCR modulation during the last solar cycles could be conditioned by some disturbances of processes in the convective zone of the Sun at the change of the current secular cycle. [1] Lavrukhina A K and Ustinova G K 1990 Meteorites as Probes of Cosmic Ray Variations (Moscow: Nauka) [2] Stozhkov Yu I et al. 2009 Adv. Space Res. 44 1124-37 [3] Alexeev V A et al. 2013 Journal of Physics: Conf. Ser. 409 012146

Alexeev, Victor; Ustinova, Galina; Povinec, Pavel; Laubenstein, Matthias

332

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

333

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.

334

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

335

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

336

Time-dependent radiation hazard estimations during space flights  

NASA Astrophysics Data System (ADS)

Cosmic particle radiation is a limiting factor for the out of magnetosphere crewed flights. The cosmic radiation uncrewed flights inside heliosphere and crewed flights inside of magnetosphere tend to become a routine procedure, whereas there have been only few shot time flights out of it (Apollo missions 1969-1972) with maximum duration less than a month. Long term crewed missions set much higher requirements to the radiation shielding, primarily because of long exposition term. Inside the helosphere there are two main sources of cosmic radiation: galactic cosmic rays (GCR) and coronal mass ejections (CME). GCR come from the outside of heliosphere forming a background of overall radiation that affects the spacecraft. The intensity of GCR is varied according to solar activity, increasing with solar activity decrease and backward, with the modulation time (time between nearest maxima) of 11 yeas. CME are shot term events, comparing to GCR modulation time, but are much more energetic. The probability of CME increases with the increase of solar activity. Time dependences of the intensity of these two components encourage looking for a time window of flight, when intensity and affection of CME and GCR would be minimized. Applying time dependent models of GCR spectra [1] and estimations of CME we show the time dependence of the radiation dose in a realistic human phantom [2] inside the shielding capsule. We pay attention to the shielding capsule design, looking for an optimal geometry parameters and materials. Different types of particles affect differently on the human providing more or less harm to the tissues. Incident particles provide a large amount of secondary particles while propagating through the shielding capsule. We make an attempt to find an optimal combination of shielding capsule parameters, namely material and thickness, that will effectively decrease the incident particle energy, at the same time minimizing flow of secondary induced particles and minimizing most harmful particle types flows. 1.Nymmik et. al., “Galactic cosmic ray flux simulation and prediction”, Adv. Space Res. 17:19-30, (1996); 2. Xu et. al., “VIP-Man: an image-based whole-body adult male model constructed from color photographs of the Visible Human Project for multi-particle Monte Carlo calculations” Health Phys. 78:476-86, (2000).

Dobynde, Mikhail; Shprits, Yuri; Drozdov, Alexander

337

A space radiation shielding model of the Martian radiation environment experiment (MARIE)  

NASA Technical Reports Server (NTRS)

The 2001 Mars Odyssey spacecraft was launched towards Mars on April 7, 2001. Onboard the spacecraft is the Martian radiation environment experiment (MARIE), which is designed to measure the background radiation environment due to galactic cosmic rays (GCR) and solar protons in the 20-500 MeV/n energy range. We present an approach for developing a space radiation-shielding model of the spacecraft that includes the MARIE instrument in the current mapping phase orientation. A discussion is presented describing the development and methodology used to construct the shielding model. For a given GCR model environment, using the current MARIE shielding model and the high-energy particle transport codes, dose rate values are compared with MARIE measurements during the early mapping phase in Mars orbit. The results show good agreement between the model calculations and the MARIE measurements as presented for the March 2002 dataset. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Atwell, W.; Saganti, P.; Cucinotta, F. A.; Zeitlin, C. J.

2004-01-01

338

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

339

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

340

Radiation Physics for Space and High Altitude Air Travel  

NASA Technical Reports Server (NTRS)

Galactic cosmic rays (GCR) are of extra-solar origin consisting of high-energy hydrogen, helium, and heavy ions. The GCR are modified by physical processes as they traverse through the solar system, spacecraft shielding, atmospheres, and tissues producing copious amounts of secondary radiation including fragmentation products, neutrons, mesons, and muons. We discuss physical models and measurements relevant for estimating biological risks in space and high-altitude air travel. Ambient and internal spacecraft computational models for the International Space Station and a Mars mission are discussed. Risk assessment is traditionally based on linear addition of components. We discuss alternative models that include stochastic treatments of columnar damage by heavy ion tracks and multi-cellular damage following nuclear fragmentation in tissue.

Cucinotta, F. A.; Wilson, J. W.; Goldhagen, P.; Saganti, P.; Shavers, M. R.; McKay, Gordon A. (Technical Monitor)

2000-01-01

341

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

342

Galactic Cosmic Ray Origin Sites: Supernova Remnants and Superbubbles  

E-print Network

We discuss processes in galactic cosmic ray (GCR) acceleration sites - supernova remnants, compact associations of young massive stars, and superbubbles. Mechanisms of efficient conversion of the mechanical power of the outflows driven by supernova shocks and fast stellar winds of young stars into magnetic fields and relativistic particles are discussed. The high efficiency of particle acceleration in the sources implies the importance of nonlinear feedback effects in a symbiotic relationship where the magnetic turbulence required to accelerate the CRs is created by the accelerated CRs themselves. Non-thermal emission produced by relativistic particles (both those confined in and those that escape from the cosmic accelerators) can be used to constrain the basic physical models of the GCR sources. High resolution X-ray synchrotron imaging, combined with GeV-TeV gamma ray spectra, is a powerful tool to probe the maximum energies of accelerated particles. Future MeV regime spectroscopy will provide unique inform...

Bykov, A M; Gladilin, P E; Osipov, S M; 10.1063/1.4772219

2012-01-01

343

Effects of radiobiological uncertainty on vehicle and habitat shield design for missions to the moon and Mars  

NASA Technical Reports Server (NTRS)

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, John W.; Nealy, John E.; Schimmerling, Walter; Cucinotta, Francis A.; Wood, James S.

1993-01-01

344

Galactic Cosmic Rays in the Outer Heliosphere  

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

Florinski, V.; Washimi, H.; Pogorelov, N. V.; Adams, J. H.

2010-01-01

345

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

346

MARIE: Current Status and Results from 20 Months of Observations at Mars  

NASA Technical Reports Server (NTRS)

The MARIE instrument aboard the 2001 Mars Odyssey spacecraft detects energetic charged particles in the Galactic Cosmic Radiation (GCR) and during solar particle events (SPE) [1]. As of this writing (January 2004), MARIE has been turned off, after losing communication with the spacecraft during the large SPE of October 28, 2003. However, during the prior 20 months, MARIE collected data almost continuously, observing several solar events and the nearly-constant GCR. There is still a possibility the instrument can be recovered, and troubleshooting efforts are scheduled to begin in May 2004, following the completion of the primary missions of MER-A (Spirit) and MER-B (Opportunity). At present, Odyssey is acting as a telecommunications relay for the rovers and only routine science operations are permitted in this mode.

Zeitlin, C.; Andersen, V.; Atwell, W.; Cleghorn, T. F.; Cucinotta, F. A.; Lee, K. T.; Pinsky, L.; Saganti, P.

2004-01-01

347

Galactic cosmic ray abundances and spectra behind defined shielding  

NASA Technical Reports Server (NTRS)

Linear Energy Transfer (LET) spectra have been measured for lunar missions and for several near Earth orbits ranging from 28 deg to 83 deg inclination. In some of the experiments the flux of Galactic Cosmic Rays (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.

Heinrich, W.; Benton, E. V.; Wiegel, B.; Zens, R.; Rusch, G.

1994-01-01

348

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

349

Long term variation of the solar diurnal anisotropy of galactic cosmic rays observed with the Nagoya multi-directional muon detector  

E-print Network

We analyze the three dimensional anisotropy of the galactic cosmic ray (GCR) intensities observed independently with a muon detector at Nagoya in Japan and neutron monitors over four solar activity cycles. We clearly see the phase of the free-space diurnal anisotropy shifting toward earlier hours around solar activity minima in A>0 epochs, due to the reduced anisotropy component parallel to the mean magnetic field. The average parallel component is consistent with a rigidity independent spectrum, while the perpendicular component increases with GCR rigidity. We suggest that this harder spectrum of the perpendicular component is due to contribution from the drift streaming. We find that the bidirectional latitudinal density gradient is positive in A>0 epoch, while it is negative in A0 and A0. We also find, however, that parallel mean free path (radial gradient) appears to persistently increase (decreasing) in the last three cycles of weakening solar activity. We suggest that simple differences between these pa...

Munakata, K; Kato, C; Kota, J

2014-01-01

350

A space radiation shielding model of the Martian radiation environment experiment (MARIE).  

PubMed

The 2001 Mars Odyssey spacecraft was launched towards Mars on April 7, 2001. Onboard the spacecraft is the Martian radiation environment experiment (MARIE), which is designed to measure the background radiation environment due to galactic cosmic rays (GCR) and solar protons in the 20-500 MeV/n energy range. We present an approach for developing a space radiation-shielding model of the spacecraft that includes the MARIE instrument in the current mapping phase orientation. A discussion is presented describing the development and methodology used to construct the shielding model. For a given GCR model environment, using the current MARIE shielding model and the high-energy particle transport codes, dose rate values are compared with MARIE measurements during the early mapping phase in Mars orbit. The results show good agreement between the model calculations and the MARIE measurements as presented for the March 2002 dataset. PMID:15791735

Atwell, W; Saganti, P; Cucinotta, F A; Zeitlin, C J

2004-01-01

351

A space radiation shielding model of the Martian radiationenvironment experiment (MARIE)  

SciTech Connect

The 2001 Mars Odyssey spacecraft was launched towards Mars on April 7, 2001. On board the spacecraft is the Martian radiation environment experiment (MARIE), which is designed to measure the background radiation environment due to galactic cosmic rays (GCR) and solar protons in the 20 500 MeV/n energy range. We present an approach for developing a space radiation-shielding model of the spacecraft that includes the MARIE instrument in the current mapping phase orientation. A discussion is presented describing the development and methodology used to construct the shielding model. For a given GCR model environment, using the current MARIE shielding model and the high-energy particle transport codes, dose rate values are compared with MARIE measurements during the early mapping phase in Mars orbit. The results show good agreement between the model calculations and the MARIE measurements as presented for the March 2002 dataset.

Atwell, William; Saganti, Premkumar; Cucinotta, Francis A.; Zeitlin, Cary J.

2004-12-01

352

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

353

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

354

Results from the Martian Radiation Environment Experiment MARIE  

NASA Technical Reports Server (NTRS)

One of the three science instruments aboard the 2001 Mars Odyssey spacecraft is the Martian Radiation Environment Experiment, MARIE. MARIE consists of a stack of silicon detectors, augmented by a Cerenkov detector. MARIE is designed to measure a portion of the particle spectrum of the Galactic Cosmic Rays (GCR), as well as the high fluxes of low-energy protons (energies less than about 100 MeV) that are intermittently produced by active regions on the sun in Solar Particle Events (SPE). MARIE is providing the first detailed information about the radiation environment near Mars.measurements. MARIE has been operating successfully for nearly a year. Solar particle events of considerable interest have been observed, and data have been obtained that will yield GCR spectra from a novel observation point in the solar system.

Zeitlin, C.; Cleghorn, T.; Cucinotta, F.; Saganti, P.; Andersen, V.; Lee, K.; Pinsky, L.; Atwell, W.; Turner, R.

2003-01-01

355

Suppression of gross chromosomal rearrangements by a new alternative replication factor C complex  

SciTech Connect

Defects in DNA replication fidelity lead to genomic instability. Gross chromosomal rearrangement (GCR), a type of genomic instability, is highly enhanced by various initial mutations affecting DNA replication. Frequent observations of GCRs in many cancers strongly argue the importance of maintaining high fidelity of DNA replication to suppress carcinogenesis. Recent genome wide screens in Saccharomyces cerevisiae identified a new GCR suppressor gene, ELG1, enhanced level of genome instability gene 1. Its physical interaction with proliferating cell nuclear antigen (PCNA) and complex formation with Rfc2-5p proteins suggest that Elg1 functions to load/unload PCNA onto DNA during a certain DNA metabolism. High level of DNA damage accumulation and enhanced phenotypes with mutations in genes involved in cell cycle checkpoints, homologous recombination (HR), or chromatin assembly in the elg1 strain suggest that Elg1p-Rfc2-5p functions in a fundamental DNA metabolism to suppress genomic instability.

Banerjee, Soma; Sikdar, Nilabja [Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, 49 Convent Drive, Room 4A22, Bethesda, MD 20892 (United States); Myung, Kyungjae [Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, 49 Convent Drive, Room 4A22, Bethesda, MD 20892 (United States)], E-mail: kmyung@nhgri.nih.gov

2007-10-26

356

[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

357

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

358

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

359

Space Radiation and Exploration - Information for the Augustine Committee Review  

NASA Technical Reports Server (NTRS)

Space radiation presents significant health risks including mortality for Exploration missions: a) Galactic cosmic ray (GCR) heavy ions are distinct from radiation that occurs on Earth leading to different biological impacts. b) Large uncertainties in GCR risk projections impact ability to design and assess mitigation approaches and select crew. c) Solar Proton Events (SPEs) require new operational and shielding approaches and new biological data on risks. Risk estimates are changing as new scientific knowledge is gained: a) Research on biological effects of space radiation show qualitative and quantitative differences with X- or gamma-rays. b) Expert recommendations and regulatory policy are changing. c) New knowledge leads to changes in estimates for the number of days in space to stay below Permissible Exposure Limits (PELS).

Cucinotta, Francis; Semones, Edward; Kim, Myung-Hee; Jackson, Lori

2009-01-01

360

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

361

Effects of Nuclear Cross Sections at Different Energies on the Radiation Hazard from Galactic Cosmic Rays  

NASA Technical Reports Server (NTRS)

The radiation hazard for astronauts from galactic cosmic rays is a major obstacle in long duration human space explorations. Space radiation transport codes have been developed to calculate radiation environment on missions to the Moon, Mars or beyond. We have studied how uncertainties in fragmentation cross sections at different energies affect the accuracy of predictions from such radiation transport. We find that, in deep space, cross sections between 0.3 and 0.85 GeV/u usually have the largest effect on dose-equivalent behind shielding in solar minimum GCR environments, and cross sections between 0.85 and 1.2 GeV/u have the largest effect in solar maximum GCR environments. At the International Space Station, cross sections at higher energies have the largest effect due to the geomagnetic cutoff.

Lin, Z. W.; Adams, J. H., Jr.

2006-01-01

362

Effects of nuclear cross sections at different energies on the radiation hazard from galactic cosmic rays.  

PubMed

The radiation hazard for astronauts from galactic cosmic rays (GCR) is a major obstacle to long-duration human space exploration. Space radiation transport codes have been developed to calculate the radiation environment on missions to the Moon, Mars, and beyond. We have studied how uncertainties in fragmentation cross sections at different energies affect the accuracy of predictions from such radiation transport calculations. We find that, in deep space, cross sections at energies between 0.3 and 0.85 GeV/nucleon have the largest effect in solar maximum GCR environments. At the International Space Station, cross sections at higher energies have the largest effect due to the geomagnetic cutoff. PMID:17316078

Lin, Z W; Adams, J H

2007-03-01

363

Solar modulation and nuclear fragmentation effects in galactic cosmic ray transport through shielding  

NASA Technical Reports Server (NTRS)

Crews of manned interplanetary missions may accumulate significant radiation exposures from the Galactic Cosmic Ray (GCR) environment in space. Estimates of how these dose levels are affected by the assumed temporal and spatial variations in the composition of the GCR environment, and by the effects of the spacecraft and body self-shielding on the transported fields are presented. In this work, the physical processes through which shielding alters the transported radiation fields are described. We then present estimates of the effects on model calculations of (1) nuclear fragmentation model uncertainties, (2) solar modulation, (3) variations between solar cycles, and (4) proposed changes to the quality factors which relate dose equivalent to absorbed dose.

Townsend, L. W.; Cucinotta, C. F.; Wilson, J. W.; Shinn, J. L.; Badhwar, G.

1994-01-01

364

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

365

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

366

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

367

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

368

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

369

Noble gas based solar flare exposure history of lunar rocks and soils  

Microsoft Academic Search

Quantitative techniques are described for the first time for the isolation of the solar-cosmic-ray (SCR)-produced Ne and Ar components for the estimation of the SCR-exposure ages of lunar rocks. SCR and galactic cosmic ray (GCR) ages of 1.7 + or - 0.2 m.y. and 3.7 + or 0.3 m.y. respectively, have been determined for the Apollo 16 rock 61016 using

M. N. Rao; T. R. Venkatesan; J. N. Goswami; C. M. Nautiyal; J. T. Padia

1979-01-01

370

Projected disappearance of the 11-year cyclic minimum of galactic cosmic ray intensity in the antapex direction within the outer heliosphere  

Microsoft Academic Search

This paper reports observed galactic cosmic ray (GCR) intensity (kinetic energy T > 80 MeV\\/nucleon) by the University of Iowa instrument on the interplanetary spacecraft Pioneer 10 (P10) for the thirty-year period, 1972–2002, during which it moved outward from 1 to 80 AU heliocentric radial distance (r). The trajectory of P10 since 1976 was in the approximate direction of the

James A. Van Allen; Bruce A. Randall

2005-01-01

371

Multi-Scale Model of Galactic Cosmic Ray Effects on the Hippocampus  

NASA Astrophysics Data System (ADS)

An important concern for risk assessment from galactic cosmic ray (GCR) exposures is impacts to the central nervous systems including changes in cognition, and associations with increased risk of Alzheimer’s disease (AD). AD, which affects about 50 percent of the population above age 80-yr, is a degenerative disease that worsens with time after initial onset leading to death, and has no known cure. AD is difficult to detect at early stages, and the small number of epidemiology studies that have considered the possibility have not identified an association with low dose radiation. However, experimental studies in transgenic mice suggest the possibility exits. We discuss modeling approaches to consider mechanisms whereby GCR would accelerate the occurrence of AD to earlier ages. Biomarkers of AD include Amyloid beta plaques, and neurofibrillary tangles (NFT) made up of aggregates of the hyper-phosphorylated form of the micro-tubule associated, tau protein. Related markers include synaptic degeneration, dendritic spine loss, and neuronal cell loss through apoptosis. GCR may affect these processes by causing oxidative stress, aberrant signaling following DNA damage, and chronic neuro-inflammation. Cell types considered in multi-scale models are neurons, astrocytes, and microglia. We developed biochemical and cell kinetics models of DNA damage signaling related to glycogen synthase kinase-3 beta and neuro-inflammation, and considered approaches to develop computer simulations of GCR induced cell interactions and their relationships to Amyloid beta plaques and NFTs. Comparison of model results to experimental data for the age specific development of plaques in transgenic mice and predictions of space radiation effects will be discussed.

Cucinotta, Francis

372

Radiation risk predictions for Space Station Freedom orbits  

NASA Astrophysics Data System (ADS)

Risk assessment calculations are presented for the preliminary proposed solar minimum and solar maximum orbits for Space Station Freedom (SSF). Integral linear energy transfer (LET) fluence spectra are calculated for the trapped proton and GCR environments. Organ dose calculations are discussed using the computerized anatomical man model. The cellular track model of Katz is applied to calculate cell survival, transformation, and mutation rates for various aluminum shields. Comparisons between relative biological effectiveness (RBE) and quality factor (QF) values for SSF orbits are made.

Cucinotta, Francis A.; Atwell, William; Weyland, Mark; Hardy, Alva C.; Wilson, John W.; Townsend, Lawrence W.; Shinn, Judy L.; Katz, Robert

1991-06-01

373

Sliding wear behavior of Cr–Mo–Cu alloy cast irons with and without nano-additives  

Microsoft Academic Search

In this paper, the microstructures of Cr–Mo–Cu alloy cast irons with and without nano-additives were characterized by scanning electron microscope (SEM) and energy diffraction spectrum analyser (EDS). The dry sliding wear tests were carried out using a pin-on-disk wear tester against GCr15 steel balls under fixed normal load and rotating velocity. The study aimed to illustrate the effect of graphite

You Wang; Zhaoyi Pan; Zheng Wang; Xiaoguang Sun; Liang Wang

2011-01-01

374

Solar flare neon composition and solar cosmic-ray exposure ages based on lunar mineral separates  

Microsoft Academic Search

Etched pyroxene grain-size separates from lunar soils 14148 and 24087 and etched feldspar grain-size separates from soil 61221 are analyzed for neon isotopic and elemental composition, and the procedures to isolate the implanted solar flare (SF) neon and solar and Galactic cosmic-ray (SCR and GCR)-produced Ne components in these samples are discussed. These results indicate that the SF neon composition

C. M. Nautiyal; J. T. Padia; M. N. Rao; T. R. Venkatesan

1986-01-01

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

PAHs in the Chinese environment: levels, inventory mass, source and toxic potency assessment.  

PubMed

This paper presents a systematic but preliminary study on the levels, inventory mass, emission sources and risk of exposure to PAHs in China by examining 14 polycyclic aromatic hydrocarbons (from the 16 priority PAHs listed by the U.S. EPA, excluding naphthalene and acenaphthylene) in four main environmental media (air, water, soil and sediment). The concentration of individual PAHs in the air, soil, freshwater, seawater, freshwater sediment and marine sediment of China was compared with the global concentration range (GCR) of PAHs from a large number of studies. The PAH levels were found at the high end of the GCR in the air, at the upper middle of the GCR in the water body, and at the middle of the GCR in the soil and sediment. These indicate that PAHs still are emitted heavily in China. About 530?000 tons of ?14PAH was estimated to be distributed into these four media in China. Soil possesses the highest proportion of the PAHs (60%), and the air has the lowest proportion (<0.5%). Therefore, the soil and sediment play an important role in the storage of PAHs. More than 10 thousand tons of PAHs are emitted from all kinds of sources. Firewood, straw, domestic and coking were considered as the main emissions of PAHs in the energy supply. A benzo[a]pyrene (BaP) based hazard quotient (HQ) was introduced to assess the potential toxic risk of exposure. The terrestrial water environment was found to have a high BaP exposure. The HQ value was more than 1 for 58% of freshwater and 39% of freshwater sediment samples. Urban and developed sites were considered to have high BaP exposure risk. PMID:23665869

Wang, Ji-Zhong; Zhu, Cheng-Zhu; Chen, Tian-Hu

2013-06-01

377

The influence of cosmic rays on the size of the Antarctic Ozone Hole  

E-print Network

The Antarctic region in which severe ozone depletion has taken place is known as the ozone hole. This region has two basic indicators: the area, where the ozone abundance is low (size), and the quantity of ozone mass deficit (depth). The energetic particles that penetrate deeply into the atmosphere and galactic cosmic rays (GCR) modify the ozone abundance in the stratosphere. With this research project, we are looking for evidence of a connection between variations in the cosmic ray flux and variations in the size of the ozone hole. In addition, we are looking for signs of the kind of processes that physically connect GCR fluxes with variations in the stratospheric ozone hole size (OHS) in the Antarctic region. With this goal in mind, we also analyze here the atmospheric temperature (AT) anomalies, which have often been linked with such variations. Using Morlet's wavelet spectral analysis to compute the coherence between two time series, we found that during the analyzed period (1982-2005), there existed a common signal of around 3 and 5 years between the OHS and GCR time series, during September and November, respectively. In both cases, the relationship showed a time-dependent anti-correlation between the two series. On the other hand, for October the analysis showed a time-dependent correlation that occurs around 1.7 years. These results seem to indicate that there exist at least two kinds of modulation processes of GCR fluxes on the OHS that work simultaneously but that change their relative relevance along the timeline.

M. Alvarez Madrigal; J. Perez Peraza; V. M. Velasco

2010-01-15

378

Sunspot activity and cosmic ray modulation at 1 a.u. for 1900-2013  

NASA Astrophysics Data System (ADS)

The descent of sunspot cycle 23 to an unprecedented minimum of long duration in 2006-2009 led to a prolonged galactic cosmic ray (GCR) recovery to the highest level observed in the instrumental era for a variety of energetic charged particle species on Earth, over a wide range of rigidities. The remarkable GCR increase measured by several ground-based, balloon-borne, and detectors on a satellite is described and discussed. It is accompanied by a decrease in solar wind velocity and interplanetary magnetic field at 1 a.u., reaching the lowest values since measurements of the solar wind began in October 1963; the solar polar field strength (?T) measured at the Wilcox Solar Observatory (WSO) is also significantly reduced compared to prior cycles since the start of the program in 1976, the polar field in the northern hemisphere reversed in June 2012 and again in February 2014, that in the southern hemisphere reversed in July 2013. If updates of WSO data confirm the second reversal in northern solar hemisphere, it would pose a serious challenge to the Dynamo Theory. The long-term change in solar behavior may have begun in 1992, perhaps earlier. The physical underpinnings of these solar changes need to be understood and their effect on GCR modulation processes clarified. The study discusses the recent phenomena in the context of GCR modulation since 1900. These happenings affected our empirical predictions for the key parameters for the next two sunspot cycles (they may be progressively less active than sunspot cycle 24) but it enhanced support for our prediction that solar activity is descending into a Dalton-like grand minimum in the middle of the twentyfirst century, reducing the frequency of the coronal mass ejections; they determine the space weather affecting the quality of life on Earth, radiation dose for hardware and human activities in space as well as the frequency of large Forbush decreases at 1 a.u.

Ahluwalia, H. S.

2014-10-01

379

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

380

ISOLATED WOLF-RAYET STARS AND O SUPERGIANTS IN THE GALACTIC CENTER REGION IDENTIFIED VIA PASCHEN-{alpha} EXCESS  

SciTech Connect

We report the discovery of 19 hot, evolved, massive stars near the Galactic center region (GCR). These objects were selected for spectroscopy owing to their detection as strong sources of Paschen-{alpha} (P{alpha}) emission-line excess, following a narrowband imaging survey of the central 0.{sup 0}65 x 0.{sup 0}25 (l, b) around Sgr A* with the Hubble Space Telescope. Discoveries include six carbon-type (WC) and five nitrogen-type (WN) Wolf-Rayet stars, six O supergiants, and two B supergiants. Two of the O supergiants have X-ray counterparts having properties consistent with solitary O stars and colliding-wind binaries. The infrared photometry of 17 stars is consistent with the Galactic center distance, but 2 of them are located in the foreground. Several WC stars exhibit a relatively large infrared excess, which is possibly thermal emission from hot dust. Most of the stars appear scattered throughout the GCR, with no relation to the three known massive young clusters; several others lie near the Arches and Quintuplet clusters and may have originated within one of these systems. The results of this work bring the total sample of Wolf-Rayet (WR) stars in the GCR to 88. All sources of strong P{alpha} excess have been identified in the area surveyed with HST, which implies that the sample of WN stars in this region is near completion, and is dominated by late (WNL) types. The current WC sample, although probably not complete, is almost exclusively dominated by late (WCL) types. The observed WR subtype distribution in the GCR is a reflection of the intrinsic rarity of early subtypes (WNE and WCE) in the inner Galaxy, an effect that is driven by metallicity.

Mauerhan, J. C.; Stolovy, S. R. [Infrared Processing and Analysis Center, California Institute of Technology, Mail Code 220-6, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Cotera, A. [SETI Institute, 515 North Whisman Road, Mountain View, CA 94043 (United States); Dong, H.; Wang, Q. D. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Morris, M. R. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Lang, C., E-mail: mauerhan@ipac.caltech.edu [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52245 (United States)

2010-12-10

381

Time-Variability in the Interstellar Boundary Conditions of the Heliosphere: Effect of the Solar Journey on the Galactic Cosmic Ray Flux at Earth  

Microsoft Academic Search

During the solar journey through galactic space, variations in the physical properties of the surrounding interstellar medium\\u000a (ISM) modify the heliosphere and modulate the flux of galactic cosmic rays (GCR) at the surface of the Earth, with consequences\\u000a for the terrestrial record of cosmogenic radionuclides. One phenomenon that needs studying is the effect on cosmogenic isotope\\u000a production of changing anomalous

Priscilla C. Frisch; Hans-Reinhard Mueller

2011-01-01

382

MCNPX Cosmic Ray Shielding Calculations with the NORMAN Phantom Model  

NASA Technical Reports Server (NTRS)

The United States is planning manned lunar and interplanetary missions in the coming years. Shielding from cosmic rays is a critical aspect of manned spaceflight. These ventures will present exposure issues involving the interplanetary Galactic Cosmic Ray (GCR) environment. GCRs are comprised primarily of protons (approx.84.5%) and alpha-particles (approx.14.7%), while the remainder is comprised of massive, highly energetic nuclei. The National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) has commissioned a joint study with Los Alamos National Laboratory (LANL) to investigate the interaction of the GCR environment with humans using high-fidelity, state-of-the-art computer simulations. The simulations involve shielding and dose calculations in order to assess radiation effects in various organs. The simulations are being conducted using high-resolution voxel-phantom models and the MCNPX[1] Monte Carlo radiation-transport code. Recent advances in MCNPX physics packages now enable simulated transport over 2200 types of ions of widely varying energies in large, intricate geometries. We report here initial results obtained using a GCR spectrum and a NORMAN[3] phantom.

James, Michael R.; Durkee, Joe W.; McKinney, Gregg; Singleterry Robert

2008-01-01

383

Inflammatory cellular phenotypes and molecular mechanisms of glucocorticoid resistance in patients with bronchial asthma.  

PubMed

Asthma shows heterogeneity in the cellular sources of inflammation and response to therapy. Although glucocorticoids (GC) are very effective for the treatment of most patients with asthma, an important subgroup of patients fails to show clinical improvement. GC resistance (GC-R) could result from either inherited or acquired variation in GC sensitivity. Diverse cells, such as T helper (Th)1 cells, Th2 cells, and Th17 cells, and innate immunity associated pathways are involved in GC-R asthma. The GC receptor (GR) plays a central role in GC sensitivity. Recent molecular biological studies have revealed the involvement of protein kinase signaling to GR, GR phosphorylation, interactions of GR with excessive activation of transcription factors, and impaired histone deacetylase (HDAC). Long-acting ??-adrenoceptor agonists (LABAs) may improve the clinical efficacy of GCs by enhancing GR function. Inhibitors of kinase pathways, such as p38 mitogen-activated protein kinase (MAPK) inhibitors and phosphoinositide-3-kinase (PI3K)? inhibitors, are candidates for new therapeutic agents for GC-R asthma. PMID:23597084

Matsumura, Yasuhiro

2013-01-01

384

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

385

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

386

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

387

Calibration of the Galactic Cosmic Ray Flux  

NASA Technical Reports Server (NTRS)

We report first Xe data on the cross-calibration of I-129-Xe-129(sub n) ages with conventional CRE ages, a method which is expected to provide information on the long-term constancy of the galactic cosmic ray (GCR) flux. We studied isotopic signatures of Xe released in stepwise heating, decomposition and melting of troilites in the Cape York iron meteorite to identify isotopic shifts in Xe-129 and Xe-131 due to neutron capture in Te-128 and Te-130. We also resolve components due to extinct 129I, spallation and fission Xe. There has recently been much speculation on the constancy of GCR over long time scales, as may be inferred from iron meteorites. If GCRs originate from supernova events, this provides the basis for postulating increased fluxes at locations with higher than average densities of supernovae, specifically in OB-associations. The solar system at present appears to be inside a local bubble between spiral arms and may experience an increased GCR flux.

Mathew, K. J.; Marti, K.

2004-01-01

388

Rigidity Dependence of the Long-Term Variations of Galactic Cosmic-Ray Intensity in Relation to the Interplanetary Magnetic-Field Turbulence: 1968 - 2002  

NASA Astrophysics Data System (ADS)

We studied the relationship between the power-law exponent ? on the rigidity R of the spectrum of galactic cosmic-ray (GCR) intensity variation ( ?D( R)/ D( R)? R - ? ) and the exponents ? y and ? z of the power spectral density (PSD) of the B y and B z components of the interplanetary magnetic field (IMF) turbulence (PSD˜ f - ? , where f is the frequency). We used the data from neutron monitors and IMF for the period of 1968 - 2002. The exponents ? y and ? z were calculated in the frequency interval ? f= f 2- f 1=3×10-6 Hz of the resonant frequencies ( f 1=1×10-6 Hz, f 2=4×10-6 Hz) that are responsible for the scattering of GCR particles with the rigidity range detected by neutron monitors. We found clear inverse correlations between ? and ? y or ? z when the time variations of the resonant frequencies were derived from in situ measurements of the solar wind velocity U sw and IMF strength B during 1968 - 2002. We argue that these inverse relations are a fundamental feature in the GCR modulation that is not restricted to the analyzed years of 1968 - 2002.

Siluszyk, M.; Iskra, K.; Alania, M. V.

2014-11-01

389

Nested Krylov methods and preserving the orthogonality  

NASA Technical Reports Server (NTRS)

Recently the GMRESR inner-outer iteraction scheme for the solution of linear systems of equations was proposed by Van der Vorst and Vuik. Similar methods have been proposed by Axelsson and Vassilevski and Saad (FGMRES). The outer iteration is GCR, which minimizes the residual over a given set of direction vectors. The inner iteration is GMRES, which at each step computes a new direction vector by approximately solving the residual equation. However, the optimality of the approximation over the space of outer search directions is ignored in the inner GMRES iteration. This leads to suboptimal corrections to the solution in the outer iteration, as components of the outer iteration directions may reenter in the inner iteration process. Therefore we propose to preserve the orthogonality relations of GCR in the inner GMRES iteration. This gives optimal corrections; however, it involves working with a singular, non-symmetric operator. We will discuss some important properties, and we will show by experiments that, in terms of matrix vector products, this modification (almost) always leads to better convergence. However, because we do more orthogonalizations, it does not always give an improved performance in CPU-time. Furthermore, we will discuss efficient implementations as well as the truncation possibilities of the outer GCR process. The experimental results indicate that for such methods it is advantageous to preserve the orthogonality in the inner iteration. Of course we can also use iteration schemes other than GMRES as the inner method; methods with short recurrences like GICGSTAB are of interest.

Desturler, Eric; Fokkema, Diederik R.

1993-01-01

390

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

391

Recurrent modulation of galactic cosmic rays: A comparative study between IMP, SOHO, STEREO, and Ulysses  

NASA Astrophysics Data System (ADS)

It is well known that the galactic cosmic ray (GCR) flux is modulated by Corotating Interaction Regions (CIR) in the vicinity of Earth. When Ulysses first explored high latitude regions in 1996, it was found that the flux of GCRs was still modulated on the time scale of one solar rotation, although neither the solar wind nor the interplanetary magnetic field at these latitudes showed the characteristics of CIRs. This process led to the modification of our understanding of either the heliospheric magnetic field (HMF, Fisk field) or the transport of particles perpendicular to the HMF. 12 years later, Ulysses explored these high latitude regions again. From September 2007 to September 2008, the GCR flux at Earth showed a clear 27 day solar-rotation modulation. However, the GCR flux at Ulysses from 2.6 AU to 3.7 AU and 73° to 47°, respectively, did not show the same behavior as in the 1990's as discussed before. Unlike the first time period, the two STEREO spacecraft launched in 2006 allow for additional near-Earth orbit measurements at multiple heliographic longitudes in 2008, thus allowing not only to investigate the latitudinal structure with Ulysses and SOHO but also the longitudinal distribution using STEREO, SOHO, and Ulysses.

Gieseler, Jan; Dresing, Nina; Dunzlaff, Phillip; Gómez-Herrero, Raúl; Heber, Bernd

2010-05-01

392

Temporal variability of solar activity effects on the lower atmosphere and natural climatic oscillations  

NASA Astrophysics Data System (ADS)

Temporal variability of relationships between the Earth’s climate and solar activity is a very important problem in solar-terrestrial physics. In this work we continue studying possible reasons for this variability. The temporal evolution of correlations between troposphere pressure at extratropical latitudes and characteristics of solar activity (SA) and galactic cosmic rays (GCR) are compared with natural climatic oscillations. It was found that the ~60-year variations detected earlier in the amplitude and sign of SA/GCR effects (Veretenenko and Ogurtsov, 2012) correlate well with similar variations in global temperature anomalies, as well as meteorological characteristics of the polar atmosphere (the Arctic Oscillation). The results obtained suggest that the character of SA/GCR influence on the lower atmosphere depends on the epoch of the large-scale circulation which, in turn, seems to be closely related to the state of the polar vortex forming in the stratosphere of high latitudes. The evidences for a roughly 60-year periodicity in the vortex strength, as well as an important part of this periodicity in the mechanism of solar-climatic links are provided. This work was supported by the Presidium of the Russian Academy of Sciences (Project No. 22) and Russian Foundation for Basic Research (Grant No.13-02-00783). References: Veretenenko S., Ogurtsov M. (2012) Regional and temporal variability of solar activity and galactic cosmic ray effects on the lower atmosphere circulation. Adv. Space Res. 49, 770-783.

Veretenenko, Svetlana; Ogurtsov, Maxim

393

The role of the ejecta magnetic flux on the two-step Forbush decreases  

NASA Astrophysics Data System (ADS)

A Forbush Decrease (FD) is a depression in the Galactic Cosmic Ray (GCR) background intensity, and are usually associated to the passage of an Interplanetary Coronal Mass Ejection (ICME). Magnetic Clouds (MCs) are a subset of ICMEs that are well studied, and are known to cause the deepest FDs. Usually, FDs present two steps in the depression profile, one associated to the shock arrival, and a steeper one restricted to the duration of the ejecta passage. There is a wide variety of processes responsible for the GCR depressions. For instance: the enhanced solar wind (SW) convection, reduced diffusion coefficients, enhanced adiabatic cooling, increase of the coherent magnetic field, etc. Our aim is to make a selection of FD events filtering those associated to well studied magnetic structures, such as Magnetic Clouds (MCs), in order to minimize the mixing processes involved in the ICME-GCR interactions in the resulting sample, and to study statistical properties. We determine the parameters of each FD profile and look for correlations with the associated MC parameters. We propose a method to decompose the FD profile into shock and ejecta components, and investigate correlations with the associated amplitudes of the ejecta components. We introduce the parameter, ``magnetic flux per unit length F/L'', and investigate its importance in the context of a simple ``diffusive barrier'' model. According to the correlations found, the two-step events are better represented by the ``diffusive barrier'' model, and the flux F/L is the parameter that better correlates with these events.

Masías Meza, Jimmy; Dasso, Sergio

394

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

NASA Technical Reports Server (NTRS)

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 (HZE), will be the ultimate limiting factor for astronaut career exposure. We consider herein a two-mutation, initiation-promotion, radiation-carcinogenesis model in mice in which the initiation stage is represented by a linear kinetics model of cellular repair/misrepair, including the track-structure model for heavy ion action cross-sections. The model is validated by comparison with the harderian gland tumor experiments of Alpen et al. for various ion beams. We apply the initiation-promotion model to exposures from galactic cosmic rays, using models of the cosmic-ray environment and heavy ion transport, and consider the effects of the age of the mice prior to and after the exposure and of the length of time in space on predictions of relative risk. Our results indicate that biophysical models of age-dependent radiation hazard will provide a better understanding of GCR risk than models that rely strictly on estimates of the initial slopes of these radiations.

Cucinotta, F. A.; Wilson, J. W.

1995-01-01

395

Radiation health for a Mars mission  

NASA Technical Reports Server (NTRS)

Uncertainties in risk assessments for exposure of a Mars mission crew to space radiation place limitations on mission design and operation. Large shielding penalties are imposed in order to obtain acceptable safety margins. Galactic cosmic rays (GCR) and solar particle events (SPE) are the major concern. A warning system and 'safe-haven' are needed to protect the crew from large SPE which produce lethal doses. A model developed at NASA Johnson Space Center (JSC) to describe solar modulation of GCR intensities reduces that uncertainty to less than 10 percent. Radiation transport models used to design spacecraft shielding have large uncertainties in nuclear fragmentation cross sections for GCR which interact with spacecraft materials. Planned space measurements of linear energy transfer (LET) spectra behind various shielding thicknesses will reduce uncertainties in dose-versus-shielding thickness relationships to 5-10 percent. The largest remaining uncertainty is in biological effects of space radiation. Data on effects of energetic ions in human are nonexistent. Experimental research on effects in animals and cell is needed to allow extrapolation to the risk of carcinogenesis in humans.

Robbins, Donald E.

1992-01-01

396

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

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

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

399

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

400

Radiation Shielding Optimization on Mars  

NASA Technical Reports Server (NTRS)

Future space missions to Mars will require radiation shielding to be optimized for deep space transit and an extended stay on the surface. In deep space, increased shielding levels and material optimization will reduce the exposure from most solar particle events (SPE) but are less effective at shielding against galactic cosmic rays (GCR). On the surface, the shielding provided by the Martian atmosphere greatly reduces the exposure from most SPE, and long-term GCR exposure is a primary concern. Previous work has shown that in deep space, additional shielding of common materials such as aluminum or polyethylene does not significantly reduce the GCR exposure. In this work, it is shown that on the Martian surface, almost any amount of aluminum shielding increases exposure levels for humans. The increased exposure levels are attributed to neutron production in the shield and Martian regolith as well as the electromagnetic cascade induced in the Martian atmosphere. This result is significant for optimization of vehicle and shield designs intended for the surface of Mars.

Slaba, Tony C.; Mertens, Chris J.; Blattnig, Steve R.

2013-01-01

401

Pharmacodynamics of glucocorticoids.  

PubMed

Exogenous glucocorticoids (GCs) are used as anti-inflammatory and immunosuppressive drugs in the treatment of a wide range of rheumatic and other inflammatory diseases. GCs exert their immunosuppressive, anti-inflammatory and anti-allergic effects on primary and secondary immune cells, tissues and organs via different mechanisms of action in a dose-dependent manner. However, their pleiotropic effects also lead to numerous adverse effects such as unwanted metabolic effects and osteoporosis. The mechanisms of action include the classical genomic mechanism resulting from activation of the cytosolic glucocorticoid receptor (cGCR), non-specific, non-genomic effects caused by interactions with cellular membranes, secondary non-genomic effects initiated by the cGCR and specific interactions with a membrane-bound glucocorticoid receptor (mGCR). Optimised glucocorticoids, such as selective glucocorticoid receptor agonists, are being developed to minimise the adverse effects many patients experience, especially if GCs are given at higher dosages over longer periods of time. Immunostimulatory effects of low concentrations of endogenous glucocorticoids and the influence of pre-receptor metabolism appear of interest for further investigation. The most important approach to optimise the risk-benefit ratio of GCs is to understand in more detail how the molecular mechanisms of genomic and non-genomic GC actions - and their dose-dependency - mediate the clinically wanted benefits but also the known adverse effects. PMID:22018178

Strehl, C; Spies, C M; Buttgereit, F

2011-01-01

402

Polyethylene as a radiation shielding standard in simulated cosmic-ray environments  

NASA Astrophysics Data System (ADS)

Radiation risk management for human space missions depends on accurate modeling of high-energy heavy ion transport in matter. The process of nuclear fragmentation can play a key role in reducing both the physical dose and the biological effectiveness of the radiation encountered in deep space. Hydrogenous materials and light elements are expected to be more effective shields against the deleterious effects of galactic cosmic rays (GCR) than aluminum, which is used in current spacecraft hulls. NASA has chosen polyethylene, CH 2, as the reference material for accelerator-based radiation testing of multi-function composites that are currently being developed. A detailed discussion of the shielding properties of polyethylene under a variety of relevant experimental conditions is presented, along with Monte Carlo simulations of the experiments and other Monte Carlo calculations in which the entire GCR flux is simulated. The Monte Carlo results are compared to the accelerator data and we assess the usefulness of 1 GeV/amu 56Fe as a proxy for GCR heavy ions. We conclude that additional accelerator-based measurements with higher beam energies would be useful.

Guetersloh, S.; Zeitlin, C.; Heilbronn, L.; Miller, J.; Komiyama, T.; Fukumura, A.; Iwata, Y.; Murakami, T.; Bhattacharya, M.

2006-11-01

403

[Galactic heavy charged particles damaging effect on biological structures].  

PubMed

A concept of the radiation risk of the manned interplanetary flights is proposed and substantiated. Heavy charged particles that are a component of the galactic cosmic rays (GCR) have a high damaging effect on the biological structures as great amount of energy is deposited in heavy particle tracks. The high biological effectiveness of heavy ions is observed in their action on cell genetic structures and the whole organism, including the brain structures. The hippocampus is the part of the central nervous system that is the most sensitive to radiation--first of all, to heavy charged particles. Irradiation of animals with accelerated iron ions at doses corresponding to the real fluxes of GCR heavy nuclei, to which Mars mission crews can be exposed, leads to marked behavioral function disorders in the post-irradiation period. To evaluate the radiation risk for the interplanetary flight crews, the concept of successful mission accomplishment is introduced. In these conditions, the central nervous system structures can be the critical target of GCR heavy nuclei. Their damage can modify the higher integrative functions of the brain and cause disorders in the crew members' operator performances. PMID:23789432

Grigor'ev, A I; Krasavin, E A; Ostrovski?, M A

2013-03-01

404

Effects of Nuclear Cross Sections at Different Energies on Space Radiation Exposure from Galactic Cosmic Rays  

NASA Technical Reports Server (NTRS)

Space radiation from galactic cosmic rays (GCR) is a major hazard to space crews, especially in long duration human space explorations. For this reason, they will be protected by radiation shielding that fragments the GCR heavy ions. Here we investigate how sensitive the crew's radiation exposure is to nuclear fragmentation cross sections at different energies. We find that in deep space cross sections between about 0.2 and 1.2 GeV/u have the strongest effect on dose equivalent behind shielding in solar minimum GCR environments, and cross sections between about 0.6 and 1.7 GeV/u are the most important at solar maximum'. On the other hand, at the location of the International Space Station, cross sections at_higher -energies, between about 0.6 and 1.7 GeV /u at solar minimum and between about 1.7 and 3.4 GeV/u'at,solar maximum, are the most important This is. due-to the average geomagnetic cutoff for the ISS orbit. We also show the effect of uncertainties in the fragmentation cross sections on the elemental energy spectra behind shielding. These results help to focus the studies of fragmentation cross sections on the proper energy range in order to improve our predictions of crew exposures.

Li, Zi-Wei; Adams, James H., Jr.

2007-01-01

405

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

406

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 (? ray) events. At any designated (ray traced) target point within the vehicle, the model accepts the differential flux spectrum of Galactic Cosmic Rays (GCRs) 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 s/ion. The ionizing radiation environment at LEO is represented by O'Neill's GCR model (2004), covering charged particles in the 1 ? Z ? 28 range. 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, F. F.; Xapsos, M. A.; Wilson, J. W.

2009-07-01

407

SEJITS and the quest for ubiquitous parallel software  

E-print Network

Pipe-and-Filter Agent-and-Repository Process-Control Event-Based/Implicit-Invocation Arbitrary-Systems Puppeteer Pipe-and-Filter Agent-and-Repository Process-Control Event-Based/Implicit-Invocation Arbitrary Code with a high level language (e.g. Python or Ruby) that is mapped onto a low level, efficiency

California at Berkeley, University of

408

Approximate semantic matching of heterogeneous events  

Microsoft Academic Search

Event-based systems have loose coupling within space, time and synchronization, providing a scalable infrastructure for information exchange and distributed workflows. However, event-based systems are tightly coupled, via event subscriptions and patterns, to the semantics of the underlying event schema and values. The high degree of semantic heterogeneity of events in large and open deployments such as smart cities and the

Souleiman Hasan; Sean O'Riain; Edward Curry

2012-01-01

409

NAIRAS aircraft radiation model development, dose climatology, and initial validation  

NASA Astrophysics Data System (ADS)

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway.

Mertens, Christopher J.; Meier, Matthias M.; Brown, Steven; Norman, Ryan B.; Xu, Xiaojing

2013-10-01

410

Probing Our Heliospheric History II  

NASA Astrophysics Data System (ADS)

A physical relationship between our local interstellar medium (ISM), galactic cosmic rays (GCR), and our planetary environment has long been a subject of interest to the astronomical community. Clouds of sufficient density to compress the heliosphere to within 1 AU are commonly seen throughout the galactic environment, including within the Local Bubble (LB). Such a compression would lead to an increase in the GCR flux at 1 AU and would have drastic consequences for many planetary processes such as atmospheric chemistry, lightning production, cloud cover, and DNA mutation rates for surface organisms. Prior to this work, we derived a column density profile of the ISM toward 49 bright stars along a narrow cone centered on the historical solar path. High resolution spectra were taken of NaI and CaII absorption out to a distance of 610 pc, with a median separation distance of 11 pc between adjacent stars. No absorption is seen out to a distance of 120 pc (consistent with the LB), but a complex number of absorbers is seen beyond. We now present the detection of several distinct clouds, their associated column densities, radial velocities, inferred distances, and size constraints. This combination of cloud properties allows us to derive a volume density profile of the ISM in the Sun's “rear-view mirror,” which represents one plausible record of actual ISM encounters for the Sun. We also make use of empirical relations to determine the effect these clouds would have on the historical heliosphere. Our analysis suggests that within the last 10 million years, if the Sun encountered a cloud with the same properties as we have detected along the solar historical trajectory, the Sun's termination shock would have resided inside the orbit of Uranus, with a GCR flux at Earth an order of magnitude greater than it is currently.

Wyman, Katherine; Redfield, S.

2012-05-01

411

Anterior-posterior differences in HoxD chromatin topology in limb development  

PubMed Central

A late phase of HoxD activation is crucial for the patterning and growth of distal structures across the anterior-posterior (A-P) limb axis of mammals. Polycomb complexes and chromatin compaction have been shown to regulate Hox loci along the main body axis in embryonic development, but the extent to which they have a role in limb-specific HoxD expression, an evolutionary adaptation defined by the activity of distal enhancer elements that drive expression of 5? Hoxd genes, has yet to be fully elucidated. We reveal two levels of chromatin topology that differentiate distal limb A-P HoxD activity. Using both immortalised cell lines derived from posterior and anterior regions of distal E10.5 mouse limb buds, and analysis in E10.5 dissected limb buds themselves, we show that there is a loss of polycomb-catalysed H3K27me3 histone modification and a chromatin decompaction over HoxD in the distal posterior limb compared with anterior. Moreover, we show that the global control region (GCR) long-range enhancer spatially colocalises with the 5? HoxD genomic region specifically in the distal posterior limb. This is consistent with the formation of a chromatin loop between 5? HoxD and the GCR regulatory module at the time and place of distal limb bud development when the GCR participates in initiating Hoxd gene quantitative collinearity and Hoxd13 expression. This is the first example of A-P differences in chromatin compaction and chromatin looping in the development of the mammalian secondary body axis (limb). PMID:22872084

Williamson, Iain; Eskeland, Ragnhild; Lettice, Laura A.; Hill, Alison E.; Boyle, Shelagh; Grimes, Graeme R.; Hill, Robert E.; Bickmore, Wendy A.

2012-01-01

412

Characterization of third-generation cephalosporin-resistant Escherichia coli from bloodstream infections in Denmark.  

PubMed

The aim of the study was to investigate the molecular epidemiology of 87 third-generation cephalosporin-resistant Escherichia coli (3GC-R Ec) from bloodstream infections in Denmark from 2009. Sixty-eight of the 87 isolates were extended-spectrum beta-lactamase (ESBL) producers, whereas 17 isolates featured AmpC mutations only (without a coexpressed ESBL enzyme) and 2 isolates were producing CMY-22. The majority (82%) of the ESBL-producing isolates in our study were CTX-M-15 producers and primarily belonged to phylogroup B2 (54.4%) or D (23.5%). Further, one of the two CMY-22-producing isolates belonged to B2, whereas only few of the other AmpCs isolates belonged to B2 and D. Pulsed-field gel electrophoresis revealed that both clonal and nonclonal spread of 3GC-R Ec occurred. ST131 was detected in 50% of ESBL-producing isolates. The remaining ESBL-producing isolates belonged to 17 other sequence types (STs), including several other internationally spreading STs (e.g., ST10, ST69, and ST405). The majority (93%) of the ESBL-producing isolates and one of the CMY-22-producing isolates were multiresistant. In conclusion, 3GC-R in bacteriaemic E. coli in Denmark was mostly due to ESBL production, overexpression of AmpC, and to a lesser extent to plasmid-mediated AmpC. The worldwide disseminated CTX-M-15-ST131 was strongly represented in this collection of Danish, bacteriaemic E. coli isolates. PMID:24517383

Hansen, Frank; Olsen, Stefan S; Heltberg, Ole; Justesen, Ulrik S; Fuglsang-Damgaard, David; Knudsen, Jenny D; Hammerum, Anette M

2014-08-01

413

Estimation of Effective Doses for Radiation Cancer Risks on ISS, Lunar, and Mars Missions with Space Radiation Measurement  

NASA Technical Reports Server (NTRS)

Radiation protection practices define the effective dose as a weighted sum of equivalent dose over major sites for radiation cancer risks. Since a crew personnel dosimeter does not make direct measurement of effective dose, it has been estimated with skin-dose measurements and radiation transport codes for ISS and STS missions. The Phantom Torso Experiment (PTE) of NASA s Operational Radiation Protection Program has provided the actual flight measurements of active and passive dosimeters which were placed throughout the phantom on STS-91 mission for 10 days and on ISS Increment 2 mission. For the PTE, the variation in organ doses, which is resulted by the absorption and the changes in radiation quality with tissue shielding, was considered by measuring doses at many tissue sites and at several critical body organs including brain, colon, heart, stomach, thyroid, and skins. These measurements have been compared with the organ dose calculations obtained from the transport models. Active TEPC measurements of lineal energy spectra at the surface of the PTE also provided the direct comparison of galactic cosmic ray (GCR) or trapped proton dose and dose equivalent. It is shown that orienting the phantom body as actual in ISS is needed for the direct comparison of the transport models to the ISS data. One of the most important observations for organ dose equivalent of effective dose estimates on ISS is the fractional contribution from trapped protons and GCR. We show that for most organs over 80% is from GCR. The improved estimation of effective doses for radiation cancer risks will be made with the resultant tissue weighting factors and the modified codes.

Kim, M.Y.; Cucinotta, F.A.

2005-01-01

414

Pion and electromagnetic contribution to dose: Comparisons of HZETRN to Monte Carlo results and ISS data  

NASA Astrophysics Data System (ADS)

Recent work has indicated that pion production and the associated electromagnetic (EM) cascade may be an important contribution to the total astronaut exposure in space. Recent extensions to the deterministic space radiation transport code, HZETRN, allow the production and transport of pions, muons, electrons, positrons, and photons. In this paper, the extended code is compared to the Monte Carlo codes, Geant4, PHITS, and FLUKA, in slab geometries exposed to galactic cosmic ray (GCR) boundary conditions. While improvements in the HZETRN transport formalism for the new particles are needed, it is shown that reasonable agreement on dose is found at larger shielding thicknesses commonly found on the International Space Station (ISS). Finally, the extended code is compared to ISS data on a minute-by-minute basis over a seven day period in 2001. The impact of pion/EM production on exposure estimates and validation results is clearly shown. The Badhwar-O'Neill (BO) 2004 and 2010 models are used to generate the GCR boundary condition at each time-step allowing the impact of environmental model improvements on validation results to be quantified as well. It is found that the updated BO2010 model noticeably reduces overall exposure estimates from the BO2004 model, and the additional production mechanisms in HZETRN provide some compensation. It is shown that the overestimates provided by the BO2004 GCR model in previous validation studies led to deflated uncertainty estimates for environmental, physics, and transport models, and allowed an important physical interaction (?/EM) to be overlooked in model development. Despite the additional ?/EM production mechanisms in HZETRN, a systematic under-prediction of total dose is observed in comparison to Monte Carlo results and measured data.

Slaba, Tony C.; Blattnig, Steve R.; Reddell, Brandon; Bahadori, Amir; Norman, Ryan B.; Badavi, Francis F.

2013-07-01

415

Space Weather Nowcasting of Atmospheric Ionizing Radiation for Aviation Safety  

NASA Technical Reports Server (NTRS)

There is a growing concern for the health and safety of commercial aircrew and passengers due to their exposure to ionizing radiation with high linear energy transfer (LET), particularly at high latitudes. The International Commission of Radiobiological Protection (ICRP), the EPA, and the FAA consider the crews of commercial aircraft as radiation workers. During solar energetic particle (SEP) events, radiation exposure can exceed annual limits, and the number of serious health effects is expected to be quite high if precautions are not taken. There is a need for a capability to monitor the real-time, global background radiations levels, from galactic cosmic rays (GCR), at commercial airline altitudes and to provide analytical input for airline operations decisions for altering flight paths and altitudes for the mitigation and reduction of radiation exposure levels during a SEP event. The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) model is new initiative to provide a global, real-time radiation dosimetry package for archiving and assessing the biologically harmful radiation exposure levels at commercial airline altitudes. The NAIRAS model brings to bear the best available suite of Sun-Earth observations and models for simulating the atmospheric ionizing radiation environment. Observations are utilized from ground (neutron monitors), from the atmosphere (the METO analysis), and from space (NASA/ACE and NOAA/GOES). Atmospheric observations provide the overhead shielding information and the ground- and space-based observations provide boundary conditions on the GCR and SEP energy flux distributions for transport and dosimetry simulations. Dose rates are calculated using the parametric AIR (Atmospheric Ionizing Radiation) model and the physics-based HZETRN (High Charge and Energy Transport) code. Empirical models of the near-Earth radiation environment (GCR/SEP energy flux distributions and geomagnetic cut-off rigidity) are benchmarked against the physics-based CMIT (Coupled Magnetosphere- Ionosphere-Thermosphere) and SEP-trajectory models.

Mertens, Christopher J.; Wilson, John W.; Blattnig, Steve R.; Solomon, Stan C.; Wiltberger, J.; Kunches, Joseph; Kress, Brian T.; Murray, John J.

2007-01-01

416

Temporal Changes in the Rigidity Spectrum of Forbush Decreases Based on Neutron Monitor Data  

NASA Astrophysics Data System (ADS)

The Forbush decrease (Fd) of the Galactic cosmic ray (GCR) intensity and disturbances in the Earth's magnetic field generally take place simultaneously and are caused by the same phenomenon, namely a coronal mass ejection (CME) or a shock wave created after violent processes in the solar atmosphere. The magnetic cut-off rigidity of the Earth's magnetic field changes because of the disturbances, leading to additional changes in the GCR intensity observed by neutron monitors and muon telescopes. Therefore, one may expect distortion in the temporal changes in the power-law exponent of the rigidity spectrum calculated from neutron monitor data without correcting for the changes in the cut-off rigidity of the Earth's magnetic field. We compare temporal changes in the rigidity spectrum of Fds calculated from neutron monitor data corrected and uncorrected for the geomagnetic disturbances. We show some differences in the power-law exponent of the rigidity spectrum of Fds, particularly during large disturbances of the cut-off rigidity of the Earth's magnetic field. However, the general features of the temporal changes in the rigidity spectrum of Fds remain valid as they were found in our previous study. Namely, at the initial phase of the Fd, the rigidity spectrum is relatively soft and it gradually becomes hard up to the time of the minimum level of the GCR intensity. Then during the recovery phase of the Fd, the rigidity spectrum gradually becomes soft. This confirms that the structural changes of the interplanetary magnetic field turbulence in the range of frequencies of 10-6 - 10-5 Hz are generally responsible for the time variations in the rigidity spectrum we found during the Fds.

Alania, M. V.; Wawrzynczak, A.; Sdobnov, V. E.; Kravtsova, M. V.

2013-09-01

417

Probabilistic Assessment of Cancer Risk from Solar Particle Events  

NASA Technical Reports Server (NTRS)

For long duration missions outside of the protection of the Earth s magnetic field, space radiation presents significant health risks including cancer mortality. 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 include high energy protons and heavy ions. While the frequency distribution of SPEs depends strongly upon the phase within the solar activity cycle, the individual SPE occurrences themselves are random in nature. We estimated the probability of SPE occurrence using a non-homogeneous Poisson model to fit the historical database of proton measurements. Distributions of particle fluences of SPEs for a specified mission period were simulated ranging from its 5 th to 95th percentile to assess the cancer risk distribution. 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. We estimated the overall cumulative probability of GCR environment for a specified mission period using a solar modulation model for the temporal characterization of the GCR environment represented by the deceleration potential (^). Probabilistic assessment of cancer fatal risk was calculated for various periods of lunar and Mars missions. This probabilistic approach to risk assessment from space radiation is in support of mission design and operational planning for future manned space exploration missions. In future work, this probabilistic approach to the space radiation will be combined with a probabilistic approach to the radiobiological factors that contribute to the uncertainties in projecting cancer risks.

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

2010-01-01

418

3-D Color Separation Maximizing the Printer Gamut  

NASA Astrophysics Data System (ADS)

Besides having CMY colorants, most of color printers include at lease one extra colorant, black (K), to increase the density for shadow colors and to reduce the colorants required for printing shadow colors. In recent years, CMYKcm, CMYKcmk (Cyan, Magenta, Yellow, blacK, light-cyan, light-magenta, and light-black), and CMYKOG (O and G stand for Orange, and Green) or CMYKOV (V stands for Violet) ink-sets have been used in printers to reduce graininess or to extend printer color gamut. No matter how many colorants are used, a printer is often configured as a three-channel printer to simplify the color mapping process. The traditional GCR/UCR approach has been widely applied for CMY to CMYK color separation. However, this approach is not flexible for controlling K usage locally; it does not guarantee reasonable gamut usage; and it does not work very well for more than CMYK colorants. In order to solve the problems existed in traditional GCR approaches, a color separation method based on 3-D interpolation was developed. In this process, we first determine the color conversion for some important node points, which include primary colors, neutral colors, and other color ramps in the gamut surface. Then different interpolation approaches are applied to fill the entire 3-D lookup table. This approach solves the problem existed in traditional GCR that a lot of high-chroma shadow colors may be lost in the color separation step. It controls K usage globally as well as locally. It well controls ink limit in the entire gamut. It also works for the color separation for more than CMYK four colorants. Because it performs automatically without human interaction, it can be applied to general printer color calibration as well as ICC profile recreation and smart CMM implementation.

Zeng, Huanzhao

2003-01-01

419

Features of the 27-Day Variations of the Galactic Cosmic Ray Intensity and Anisotropy  

NASA Astrophysics Data System (ADS)

We study features of the 27-day variations of the galactic cosmic ray (GCR) intensity and anisotropy using data of neutron monitors and solar wind (SW) velocity. We found that the larger amplitudes of the 27-day variations of the galactic cosmic ray anisotropy and intensity for the positive polarity period (Age 0) of solar magnetic cycle than for the negative polarity period (Ale 0) in the minima epoch of solar activity are related with the heliolongitudinal asymmetry of the solar wind velocity. We reveal the long-lived (sim 22 years) active regions of the heliolongitudes being the sources of the 27-day variation of the solar wind velocity during the Age 0 period. Also, we demonstrate an existence of the clear stable 27-day waves of the GCR intensity and anisotropy with the amplitudes larger in the Age 0 than in the Ale 0 for the several individual Carrington rotations in the minima epoch of solar activity. We show that the solution of the Parker's transport equation with the heliolongitudinal asymmetry of the solar wind velocity is in the reasonable agreement with the neutron monitors experimental data. We conclude that the larger amplitudes of the 27-day variations of the galactic cosmic ray anisotropy and intensity observed by the experimental data in the Age 0 are related with the superposition of two effects: (1) the existence of the more regular heliolongitudinal asymmetry of the solar wind velocity, and (2) a coincidence of convective and drift streams of the GCR particles in comparison with the Ale 0.

Gil, A.; Modzelewska, R.; Alania, M. V.

2008-05-01

420

Effect of the shrinking dipole on solar-terrestrial energy input to the Earth's atmosphere  

NASA Astrophysics Data System (ADS)

The global average temperature of the Earth is rising rapidly. This rise is primarily attributed to the release of greenhouse gases as a result of human activity. However, it has been argued that changes in radiation from the Sun might play a role. Most energy input to the Earth is light in the visible spectrum. Our best measurements suggest this power input has been constant for the last 40 years (the space age) apart from a small 11-year variation due to the solar cycle of sunspot activity. Another possible energy input from the Sun is the solar wind. The supersonic solar wind carries the magnetic field of the Sun into the solar system. As it passes the Earth it can connect to the Earth's magnetic field whenever it is antiparallel t the Earth's field. This connection allows mass, momentum, and energy from the solar wind to enter the magnetosphere producing geomagnetic activity. Ultimately much of this energy is deposited at high latitudes in the form of particle precipitation (aurora) and heating by electrical currents. Although the energy input by this process is miniscule compared to that from visible radiation it might alter the absorption of visible radiation. Two other processes affected by the solar cycle are atmospheric entry of galactic cosmic rays (GCR) and solar energetic protons (SEP). A weak solar magnetic field at sunspot minimum facilitates GCR entry which has been implicated in creation of clouds. Large coronal mass ejections and solar flares create SEP at solar maximum. All of these alternative energy inputs and their effects depend on the strength of the Earth's magnetic field. Currently the Earth's field is decreasing rapidly and conceivably might reverse polarity in 1000 years. In this paper we describe the changes in the Earth's magnetic field and how this might affect GCR, SEP, electrical heating, aurora, and radio propagation. Whether these effects are important in global climate change can only be determined by detailed physical models.

McPherron, R. L.

2011-12-01

421

Re-calibration of the apparent 25,000 to 35,000 ybp sea level high stand: Just a moment in time some 55,000 to 70,000 years ago  

SciTech Connect

Occurrences of shallow marine and strand line sediments at or near the elevation of modern mean sea level with radiocarbon dates in the range of 25,000--35,000 ybp have been reported from the Delmarva Peninsula to the Florida Peninsula. Such dates are in conflict with established sea level curves and have consequently been written off as much older samples contaminated with small amounts of young carbon. An alternate hypothesis is that the assumed near constancy of the galactic cosmic ray (GCR) flux and consequently the C-14 production rate is not totally correct. Be-10 concentrations from ice cores suggests that possibly twice in the last 100,000 years the earth has been briefly subjected to greatly enhanced GCR fluxes. Modeling effects of the increased but brief GCR flux on the total C-14 concentrations in the ocean and biosphere suggests that apparent C-14 dates of 25K to 35K ybp on certain marine deposits may actually reflect deposition during a very brief period of time somewhere between 55K to 70K ybp. Deposits possibly effected include but are not restricted to: an unnamed beach/shore face deposit at Mockhorn Is. Virginia, Diamond City Clay at Cape Lookout NC, Cape Fear Coquina in southeastern NC, Silver Bluff at Sapelo Is. GA, and an unnamed coarse sand at St. George Is., FL. Such deposits are depositionally associated with strand line processes, either near shore, beach, or estuarine. Characteristics of the C-14 dates from such deposits include great variability in age ranges for spatially close samples including association with non-finite samples and apparent violation of the principle of superposition where older material overlies apparently younger. Interpretation of such deposits suggest deposition at or near sea level during a period of falling sea level. Correlation of such deposits north to south along the Atlantic coast suggest continued influence of the glacial forebulge and deposition topographically 5 to 10 meters below modern mean sea level.

Dockal, J.A. (Univ. of North Carolina, Wilmington, NC (United States). Dept. of Earth Sciences)

1993-03-01

422

Validation of Galactic Cosmic Radiation and Geomagnetic Transmissions  

NASA Technical Reports Server (NTRS)

The Alpha Magnet Spectrometer (AMS) was flown on Shuttle flight STS-91 in June 1998 near solar minimum. This unique spectrometer has provided very high resolution, calibrated data on the galactic hydrogen and helium rigidity spectra form approx. 100 MeV/n to approx. 200 GeV/n as a function of magnetic latitude. This paper describes a comparison of the AMS data with the Badhwar-O'Neill GCR model and the geomagnetic transmission calculated using the quiescent DGRF 1990 cutoffs. The results have strong bearing on radiation modeling for the International Space Station.

Badhwar, Gautam D.; Troung, A.; ONeill, P.; Bman, B.

2000-01-01

423

Long-Term Cosmic Ray Intensities: Physical Reconstruction  

NASA Astrophysics Data System (ADS)

Solanki et al. (2000) have recently calculated the open solar magnetic flux for the last 400 years from sunspot data. Using this reconstructed magnetic flux as an input to a simple spherically symmetric quasi-steady state model of the heliosphere, we calculate the expected differential spectra and integral intensity of galactic cosmic rays at the Earth's orbit since 1610. The calculated cosmic ray integral intensity is in good agreement with the neutron monitor measurements during the last 50 years. Moreover, using the specific yield function of cosmogenic 10 Be radionuclide production in the atmosphere, we also calculate the expected 10 Be production rate which exhibits an excellent agreement with the actual 10 Be abundance in polar ice over the last 400 years. Here we present a physical model for the long-term reconstruction of cosmic ray intensity at 1 AU. The reconstruction is based on a combination of the solar magnetic flux model and a heliospheric model. This model allows us to calculate the expected intensity of galactic cosmic rays (GCR) at the Earth's orbit for the last 400 years. Details can be found in [25]. Using the numerical recip e of Solanki et al. [21] and the group sunspot number series (Fig. 1.a) [11] we have calculated the open solar magnetic flux Fo since 1610 as shown in Fig. 1.b. In order to calculate galactic cosmic ray (GCR) spectra we use a spherically symmetric quasi-steady sto chastic simulation model described in detail elsewhere [24], which reliably describes the long-term GCR modulation during the last 50 years. In this model, the most important parameter of the heliospheric modulation of GCR is the modulation strength [10]: ? = (D - rE )V /(3?o), where D = 100 AU is the heliospheric boundary and rE = 1 AU, V = 400 km/s is the constant solar wind velocity and ?o is the rigidity indep endent part of the diffusion coefficient. Thus, all changes in the modulation strength ? in our model are related to the changing diffusion

Usoskin, I. G.; Mursula, K.; Solanki, S.K.; Schuessler, M.; Kovaltsov, G.A.

2003-07-01

424

Galactic cosmic rays measured by UVS on Voyager 1 and the end of the modulation. Is the upwind heliopause a collapsed charge-exchange layer?  

NASA Astrophysics Data System (ADS)

The detectors of the Ultraviolet Spectrographs (UVS) on Voyager 1/2 are recording a background intensity that was earlier assigned mainly to disintegrations in the radio-isotope thermoelectric generator and systematically subtracted from the signal to infer photon counting. Here, we show that it arises instead from galactic cosmic rays (GCRs). We show the GCR flux measured by UVS on Voyager 1 from 1992 to August 2013, and by comparing to data from the GCR dedicated detectors, we estimate the energy range responsible for this UVS signal, which is around 300 MeV, and the response of UVS to the GCR anisotropy. After the abrupt jumps of May and August 2012, the count rate has been only slightly fluctuating around a constant value. However, comparing it to the data from the Low Energy Charge Particle Experiment (LECP) and the Cosmic Ray Subsystem (CRS) shows that those small variations are only responses to a varying anisotropy and not to a flux change. Taking advantage of the similarity in energy range to one of the products of the CRS instrument suite, we use the ratio between the two independent signals as a proxy for the temporal evolution of the GCR spectral slope around the 300 MeV range. We show that this slope remained unchanged since August 2012 and find strong evidence that it will no longer vary, implying the end of the heliospheric modulation at those energies, and that Voyager 1 at this date is near or past the heliopause. The origin of this unexpectedly narrow and stagnating inner heliosheath is still unclear, and we discuss the potential effects of low solar wind speed episodes and subsequent self-amplified charge-exchange with interstellar neutrals, as a source of deceleration and collapse. We suggest that the quasi-static region encountered by Voyager 1 may be related to such effects, triggered by the strong solar-maximum variability. This did not happen for Voyager 2 due to its trajectory at an angle further from the heliosphere axis and a later termination shock crossing. The existence on the upwind side of a mixing layer formed by charge transfer instead of a pure plasma contact discontinuity could explain various Voyager 1 observations.

Lallement, R.; Bertaux, J. L.; Quémerais, E.; Sandel, B. R.

2014-03-01

425

[Individual characteristics of correction of the cosmonauts' vegetative status with a method of adaptive biofeedback  

NASA Technical Reports Server (NTRS)

The ability of 4 cosmonauts to voluntarily control their physiological parameters during the standing test was evaluated following a series of the adaptive feedback (AF) training sessions. Vegetative status of the cosmonauts during voluntary "relaxation" and "straining" was different when compared with its indices determined before these sessions. In addition, there was a considerable individual variability in the intensity and direction of the AF effects, and the range of parameters responding to AF. It was GCR which was the easiest one for the AF control.

Kornilova, L. N.; Cowings, P.; Arlashchenko, N. I.; Korneev, D. Iu; Sagalovich, S. V.; Sarantseva, A. V.; Toscano, W.; Kozlovskaia, I. B.

2003-01-01

426

?-? Effect and peculiarities of the 27-day variations of the galactic cosmic rays intensity, solar wind and solar activity parameters  

NASA Astrophysics Data System (ADS)

We show that the amplitudes of the 27-day variations of galactic cosmic ray (GCR) intensity, solar wind and solar activity parameters have a periodicity with duration of three to four Carrington rotation periods (3-4 CRP). We assume that the general reason for this phenomenon may be related to similar cyclicity of topological structure of the solar magnetic field lines created owing to the asymmetry of turbulent solar dynamo and solar differential rotation transforming the Sun's poloidal magnetic field to the toroidal (?-? effect), and vice versa.

Gil, A.; Alania, M. V.

2013-09-01

427

The Unusual Time History of Galactic and Anomalous Cosmic Rays at 1 AU over the Solar Minimum of Cycle 23  

NASA Astrophysics Data System (ADS)

Studies of the galactic cosmic rays temporal variations (GCRs) over the "Modern Era" (from 1950s) establish the existence of a 22-year cosmic ray modulation cycle that is dominated by the 11-year solar activity cycle but is significantly influenced by gradient and curvature drifts in the interplanetary magnetic field (IPB) in association with changes in the tilt of the heliospheric neutral current sheet over the heliomagnetic cycle. In qA<0 epochs (when positive ions flow in along the neutral sheet and out over the solar poles), the solar minimum cosmic rays intensity is peaked over a period of several months (1965, 1987) in contrast to the 3 - 4 year plateau periods for qA>0 minima when the flow pattern is reversed. However, for 200 MeV/n GCR HE at 1 AU there is a quasi-plateau region for the cycle 23 solar minimum that now extends over some 12 months. The intensity level of this component is essentially the same as that of 1965 and 1987, as is the large depression of anomalous cosmic ray ACR He (10 - 40 MeV/n) relative to the qA>0 minima. There appears to be two different solar effects, the current sheet tilt in 2007 is less than in 1987 while the magnitude of the 1P B field is at its lowest value since essentially continuous measurements began in 1963. These will have off-setting effects on the GCR intensity. 10 Be and 14 C studies have shown that previous epochs of low solar activity [Oort (1050 AD); Spoerer (1420-1540); and Maunder (1615-1715)] have been marked by high cosmic ray intensity. There were other periods of reduced solar activity [Wolf (1320) and Dalton (1810)] which were associated with more moderate enhancements of the GCR intensity. Studies using data from the Cosmic Ray Network [IMP, ACE, neutron monitors at 1 AU, and Pioneer, Voyager, and Ulysses at greater heliocentric distances] are providing a better understanding of the solar phenomena that produce the cosmic ray modulation and should lead to an understanding of the solar changes in the distant past associated with the epochs of enhanced GCR intensity.

McDonald, F. B.; Webber, W. R.; Reames, D. V.

2008-12-01

428

Radiation: Physical Characterization and Environmental Measurements  

NASA Technical Reports Server (NTRS)

In this session, Session WP4, the discussion focuses on the following topics: Production of Neutrons from Interactions of GCR-Like Particles; Solar Particle Event Dose Distributions, Parameterization of Dose-Time Profiles; Assessment of Nuclear Events in the Body Produced by Neutrons and High-Energy Charged Particles; Ground-Based Simulations of Cosmic Ray Heavy Ion Interactions in Spacecraft and Planetary Habitat Shielding Materials; Radiation Measurements in Space Missions; Radiation Measurements in Civil Aircraft; Analysis of the Pre-Flight and Post-Flight Calibration Procedures Performed on the Liulin Space Radiation Dosimeter; and Radiation Environment Monitoring for Astronauts.

1997-01-01

429

Comparison of radiation shielding properties of materials for space exploration initiative  

SciTech Connect

Radiation transport calculations were performed using the Montecarlo Intranuclear Cascade Code LAHET in order to evaluate the shielding effectiveness of CH{sub 4} and CH{sub 2} materials compared with, Water, Aluminum, Iron and Lead. In addition, calculations were performed using the deterministic straight-ahead approximation code BRYNTRN for CH{sub 4}, CH{sub 2}, B,C, Al, Fe Ta, and Pb. The use of hydrogenous material is shown to be superior in its shielding properties of particle and energy spectra of SPE and for the GCR spectra.

Divadeenam, M.; Snead, C.L. Jr.; Ward, T.E. [Brookhaven National Lab., Upton, NY (United States); Nealy, J.E. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center

1992-08-01

430

Comparison of radiation shielding properties of materials for space exploration initiative  

SciTech Connect

Radiation transport calculations were performed using the Montecarlo Intranuclear Cascade Code LAHET in order to evaluate the shielding effectiveness of CH{sub 4} and CH{sub 2} materials compared with, Water, Aluminum, Iron and Lead. In addition, calculations were performed using the deterministic straight-ahead approximation code BRYNTRN for CH{sub 4}, CH{sub 2}, B,C, Al, Fe Ta, and Pb. The use of hydrogenous material is shown to be superior in its shielding properties of particle and energy spectra of SPE and for the GCR spectra.

Divadeenam, M.; Snead, C.L. Jr.; Ward, T.E. (Brookhaven National Lab., Upton, NY (United States)); Nealy, J.E. (National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center)

1992-01-01

431

Research on dynamic wear behavior at elevated temperature of HVOF sprayed nanostructured WC-17Co coating  

NASA Astrophysics Data System (ADS)

Nanostructured WC-17Co coatings have been prepared by means of High Velocity Oxy-fuel (HVOF) technique. The wear resistance at the elevated temperature (500°C) of nanostructured coatings was compared using GCr15 steel as counterpart in sliding wear tests. The results show that when at the temperature of 500°C, the wear failure mechanism turns from plastic deformation to fracture resulted from crack propagation and adhesive wear. With the wear going, abrasive wear dominate in the coating, then turns into adhesive wear with changes of microscope.

Liu, Yan; Chen, Hui; Gou, Guoqing; Tu, Mingjing

2010-07-01

432

Miniaturized Gas Correlation Radiometer for the Detection of Trace Gases in the Martian Atmosphere  

NASA Technical Reports Server (NTRS)

We present a miniaturized and simplified version of a gas correlation radiometer (GCR) capable of simultaneously mapping multiple trace gases and identifying active regions on the Mars surface. Gas correlation radiometry (GCR) has been shown to be a sensitive and versatile method for detecting trace gases in Earth's atmosphere. Reduction of the size and mass of the GCR was achieved by implementing compact, light-weight 1 mm inner diameter hollow-core optical fibers (hollow waveguides) as the gas correlation cells. In a comparison with an Earth orbiting CO2 GCR instrument, exchanging the 10 m multipass cells with hollow waveguide gas correlation cells of equivalent path length reduces the mass from approximately 150 kg to approximately 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 1 meter in diameter by 0.05 m in height (mass and volume reductions of greater than 99%). A unique feature of this instrument is its stackable module design, with a single module for each trace gas. Each of the modules is self-contained, and fundamentally identical; differing by the bandpass filter wavelength range and gas mixtures inside the hollow-waveguide absorption cells. The current configuration contains four stacked modules for simultaneous measurements of methane (CH4), formaldehyde (H2CO), water vapor (H2O), and deuterated water vapor (HDO) but could easily 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. Preliminary results indicate that a 1 ppb detection limit is possible for both formaldehyde and methane with one second of averaging. Using non-optimized components, we have demonstrated an instrument sensitivity equivalent to approximately 30 ppb for formaldehyde, and approximately 500 ppb for methane. We expect custom bandpass filters and 6 m long waveguides to significantly improve these promising results. Ongoing testing is being conducted on water vapor and deuterated water vapor.

Melroy, Hilary R.; Wilson, Emily L.; Georgieva, Elena

2012-01-01

433

A comparative study of space radiation organ doses and associated cancer risks using PHITS and HZETRN.  

PubMed

NASA currently uses one-dimensional deterministic transport to generate values of the organ dose equivalent needed to calculate stochastic radiation risk following crew space exposures. In this study, organ absorbed doses and dose equivalents are calculated for 50th percentile male and female astronaut phantoms using both the NASA High Charge and Energy Transport Code to perform one-dimensional deterministic transport and the Particle and Heavy Ion Transport Code System to perform three-dimensional Monte Carlo transport. Two measures of radiation risk, effective dose and risk of exposure-induced death (REID) are calculated using the organ dose equivalents resulting from the two methods of radiation transport. For the space radiation environments and simplified shielding configurations considered, small differences (<8%) in the effective dose and REID are found. However, for the galactic cosmic ray (GCR) boundary condition, compensating errors are observed, indicating that comparisons between the integral measurements of complex radiation environments and code calculations can be misleading. Code-to-code benchmarks allow for the comparison of differential quantities, such as secondary particle differential fluence, to provide insight into differences observed in integral quantities for particular components of the GCR spectrum. PMID:24061091

Bahadori, Amir A; Sato, Tatsuhiko; Slaba, Tony C; Shavers, Mark R; Semones, Edward J; Van Baalen, Mary; Bolch, Wesley E