Note: This page contains sample records for the topic germcode gcr event-based from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

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

2011-01-17

2

Rap1p requires Gcr1p and Gcr2p homodimers to activate ribosomal protein and glycolytic genes, respectively.  

PubMed Central

Efficient transcription of ribosomal protein (RP) and glycolytic genes requires the Rap1p/Gcr1p regulatory complex. A third factor, Gcr2p, is required for only the glycolytic (specialized) mode of transcriptional activation. It is recruited to the complex by Gcr1p and likely mediates a change in the phosphorylation state and/or conformation of the latter. We show here that leucine zipper motifs in Gcr1p and Gcr2p (1LZ and 2LZ) are each specific to one of the two activation mechanisms-mutations in 1LZ and 2LZ impair transcription of RP and glycolytic genes, respectively. Although neither class of mutations causes more than a mild growth defect, simultaneous impairment of 1LZ and 2LZ results in a severe synthetic defect and a reduction in the expression of both sets of genes. Intracistronic complementation by point mutations in the charged e and g positions confirmed that Gcr1p/Gcr1p and Gcr2p/Gcr2p homodimers are the forms required for the different roles of the activator complex. Direct heterodimerization between 1LZ and 2LZ apparently does not occur. Dichotomous Rap1p activation and its striking requirement for distinct homodimeric subunits give cells the capacity to switch between coordinated and uncoupled RP and glycolytic gene regulation.

Deminoff, S J; Santangelo, G M

2001-01-01

3

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

4

The Dynamic Outer Heliosphere and Preliminary Analysis of GCR Trajectories  

NASA Astrophysics Data System (ADS)

We show realistic and time-varying 3D MHD models of the outer heliosphere which satisfy both Voyager 1 (V1) and Voyager 2 (V2) observed crossing times of the termination shock (TS) simultaneously. The short-term variations found are a) the TS position increases whenever a solar-wind high-ram pressure pulse collides with the TS, b) a large amplitude magneto-sonic pulse is generated downstream of the TS when a solar-wind high ram pressure pulse collides with the TS, c) the generated pulse propagates outward in the heliosheath and is reflected at the plasma sheet, and d) when the reflected pulse collides with the TS, the TS position decreases. We also present preliminary results of galactic cosmic rays (GCRs) trajectories as they respond to three-dimensional global electric and magnetic fields in the outer heliosphere. This allows us to investigate (1) how GCRs cross the heliosphere and enter the inner heliosphere, and (2) their long-term variation. Preliminary GCR distributions in the outer heliosphere are shown. GCR diffusion due to magnetic-field fluctuations is not taken into account in this analysis.

Washimi, Haruichi; Zank, Gary P.; Hu, Qiang; Tanaka, Takashi; Munakata, Kazuoki; Shinagawa, Hiroyuki

2010-12-01

5

Model Estimated GCR Particle Flux Variation - Assessment with CRIS Data  

NASA Astrophysics Data System (ADS)

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

Saganti, Premkumar

6

Engineering Event-Based Systems with Scopes  

Microsoft Academic Search

Event notification services enable loose coupling and they are therefore becoming an essential part of distributed systems' design. How- ever, the development of event services follows the early stages of pro- gramming language evolution, disregarding the need for efficient mech- anisms to structure event-based applications. In this paper, the well- known notion of scopes is introduced to event-based systems. We

Ludger Fiege; Mira Mezini; Gero Mühl; Alejandro P. Buchmann

2002-01-01

7

Asynchronous Event-Based Binocular Stereo Matching  

Microsoft Academic Search

We present a novel event-based stereo matching algorithm that exploits the asynchronous visual events from a pair of silicon retinas. Unlike conventional frame-based cameras, recent artificial retinas transmit their outputs as a continuous stream of asynchronous temporal events, in a manner similar to the output cells of the biological retina. Our algorithm uses the timing information carried by this representation

Paul Rogister; Ryad Benosman; Sio-Hoi Ieng; Patrick Lichtsteiner; Tobi Delbruck

2012-01-01

8

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

9

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

2011-09-26

10

Amorphous GCr15-Ta film formation by dynamic ion beam mixing and the film properties  

NASA Astrophysics Data System (ADS)

Ta-rich surface alloys have been prepared directly on GCr15 bearing steel (corresponding to AISI52100 steel) substrates by the dynamic ion beam mixing technique. An amorphous alloy film of a given composition can be formed when the deposition temperature and the atom-ion arrival ratio are controlled appropriately. The microstructure and composition of such films were examined using TEM, EDX and XPS. Corrosion tests in H2SO4 and NaCl solutions, as well as friction and wear tests have shown that the amorphous GCr15-Ta alloy films formed by this technology have superior chemical and physical properties.

Wang, Peilu; Liu, Zhong Yang; Jiang, Jingyun; Guo, Huachong

1991-12-01

11

The formation of the sunspot and magnetic cycles in the GCR intensity in the heliosphere  

NASA Astrophysics Data System (ADS)

We compare the different approaches (observational and theoretical) to the definition and separation of the GCR intensity variations due to the changing number and area of sunspots (the sunspot cycle) and the changing polarity of the high-latitude solar magnetic fields (the magnetic cycle). Using the theoretical approach we can consider how both types of the GCR intensity variations change with energy in different parts of the heliosphere during the minima of the sunspot cycle and their relative weights in the calculated intensity.

Kalinin, M. S.; Krainev, M. B.

2013-02-01

12

Landscape of international event-based biosurveillance  

PubMed Central

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

Hartley, DM; Nelson, NP; Walters, R; Arthur, R; Yangarber, R; Madoff, L; Linge, JP; Mawudeku, A; Collier, N; Brownstein, JS; Thinus, G; Lightfoot, N

2010-01-01

13

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

PubMed Central

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

Santangelo, G M; Tornow, J

1990-01-01

14

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

Microsoft Academic Search

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

Thomas Wilson; Kerry Lee

2008-01-01

15

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

Uemura, H; Jigami, Y

1992-01-01

16

Amorphous GCr15Ta film formation by dynamic ion beam mixing and the film properties  

Microsoft Academic Search

Ta-rich surface alloys have been prepared directly on GCr15 bearing steel (corresponding to AISI52100 steel) substrates by the dynamic ion beam mixing technique. An amorphous alloy film of a given composition can be formed when the deposition temperature and the atom-ion arrival ratio are controlled appropriately. The microstructure and composition of such films were examined using TEM, EDX and XPS.

Peilu Wang; Zhong Yang Liu; Jingyun Jiang; Huachong Guo

1991-01-01

17

Two-Time GCR-Flux Decrease Associated With March 2006 Interplanetary Shock Event  

NASA Astrophysics Data System (ADS)

We have analyzed a realistic and time-varying outer heliosphere using three-dimensional MHD simulation based on the Voyager 2 (V2) observed plasma data. When a large interplanetary shock wave, such as March 2006 event (Richardson et al. 2007) observed by V2, collides with the termination shock (TS), it is found in our simulation that a fast shock is driven downstream of the TS, and the fast shock propagates outward in the heliosheath. The contact surface propagates with plasma flow velocity in the heliosheath. On the other hand, V-1 observations of galactic cosmic rays (GCR) of 70-200 MeV indicates that a two-time Forbush-like flux-decrease was associated with the March 2006 event (Webber et al. 2009). The observed first and second decreases occurred at 2006.29 and 2006.51 respectively, while the crossings of V1 with the fast shock and contact surface in our simulation are 2006.4 and 2006.6, respectively. Hence there is about 0.1 year difference between the V1 observed two-time GCR-flux decrease and the simulated crossing time, though the time-duration between the 1st and 2nd GCR-flux decrease and that between crossings of the fast shock and contact surface are almost the same, i.e., about 0.2 years. The time-difference of 0.1 year between the observations and simulation can be explained if the interplanetary shock speed of the March 2006 event along the Sun-V1 direction is assumed to be about 10 % faster than that observed at V2. Thus the two-time GCR-flux decrease could be caused by the V1 crossings with the fast shock and the contact surface driven by the March 2006 event.

Washimi, H.; Zank, G. P.; Hu, Q.; Webb, G. M.; Shinagawa, H.

2010-12-01

18

Model for GCR-particle fluxes in stony meteorites and production rates of cosmogenic nuclides  

SciTech Connect

A model is presented for the differential fluxes of galactic-cosmic-ray (GCR) particles with energies above 1 MeV inside any spherical stony meteorite as a function of the meteorite's radius and the sample's depth. This model is based on the Reedy-Arnold equations for the energy-dependent fluxes of GCR particles in the moon and is an extension of flux parameters that were derived for several meteorites of various sizes. This flux is used to calculate the production rates of many cosmogenic nuclides as a function of radius and depth. The peak production rates for most nuclides made by the reactions of energetic GCR particles occur near the centers of meteorites with radii of 40 to 70 g cm/sup -2/. Although the model has some limitations, it reproduces well the basic trends for the depth-dependent production of cosmogenic nuclides in stony meteorites of various radii. These production profiles agree fairly well with measurements of cosmogenic nuclides in meteorites. Some of these production profiles are different than those calculated by others. The chemical dependence of the production rates for several nuclides varies with size and depth. 25 references, 8 figures.

Reedy, R.C.

1984-01-01

19

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

20

Discrete-event based simulation conceptual modeling of systems biology  

Microsoft Academic Search

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

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

2005-01-01

21

CREAM: An Infrastructure for Distributed, Heterogeneous Event-Based Applications  

Microsoft Academic Search

Applications ranging from event-based supply chain man- agement to enterprise application integration and pervasive computing depend on the timely detection and notification of events. We present Cream the event-based reactive component of the Dream middleware platform. Here we address four key issues in distributed and heteroge- neous environments: event detection and notification, event composition, an active functionality service, and ontology

Mariano Cilia; Christof Bornhövd; Alejandro P. Buchmann

2003-01-01

22

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

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

1987-01-01

23

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

24

Fully Abstract Semantics for Event-Based Simulation.  

National Technical Information Service (NTIS)

Event-based simulation is a popular technique for predicting the behavior of, among other things, digital circuits. On the other hand, applicative denotational formalisms, in which circuits are represented by functional equations with an explicit time var...

R. J. Hall

1987-01-01

25

A 3D Monte Carlo model of radiation affecting cells, and its application to neuronal cells and GCR irradiation  

Microsoft Academic Search

A 3D Monte Carlo model of radiation transport in matter is applied to study the effect of heavy ion radiation on human neuronal cells. Central nervous system effects, including cognitive impairment, are suspected from the heavy ion component of galactic cosmic radiation (GCR) during space missions. The model can count, for instance, the number of direct hits from ions, which

Artem Ponomarev; Alamelu Sundaresan; Angela Kim; Marcelo E. Vazquez; Peter Guida; Myung-Hee Kim; Francis A. Cucinotta

2008-01-01

26

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

27

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

NASA Astrophysics Data System (ADS)

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 Brookhaven National Laboratory, others at the National Institute of Radiological Sciences in Japan. These energies and ion species are representative of the heavy ion component of the Galactic Cosmic Rays (GCR), which contribute significantly to the dose and dose equivalent that will be received by astronauts on deep-space missions. A critical need for NASA is the ability to accurately model the transport of GCR heavy ions through matter, including spacecraft walls, equipment racks, and other shielding materials, as well as through tissue. Nuclear interaction cross sections are of primary importance in the GCR transport problem. These interactions generally cause the incoming ion to break up (fragment) into one or more lighter ions, which continue approximately along the initial trajectory and with approximately the same velocity the incoming ion had prior to the interaction. Since the radiation dose delivered by a particle is proportional to the square of the quantity (charge/velocity), i.e., to (Z/?)2 , fragmentation reduces the dose (and, typically, dose equivalent) delivered by incident ions. The other mechanism by which dose can be reduced is ionization energy loss, which can lead to some particles stopping in the shielding. This is the conventional notion of shielding, but it is not applicable to human spaceflight, since the particles in the GCR tend to be highly energetic and because shielding must be relatively thin in order to keep overall mass as low as possible, keeping launch costs within reason. To support these goals, our group has systematically measured a large number of nuclear cross sections, intended to be used as either input to, or validation of, NASA transport models. A database containing over 200 charge-changing cross sections, and over 2000 fragment production cross sections, is nearing completion, with most results available online. In the past year, we have been investigating the PHITS (Particle and Heavy Ion Transport System) model of Niita et al. For purposes of modeling nuclear interactions, PHITS combines the Jet AA Microscopic Transport Model (JAM) hadron cascade model, the Jaeri Quantum Molecular Dynamics (JQMD) model, and the Generalized Evaporation Model (GEM). We will present detailed comparisons of our data to the cross sections and fragment angular distributions that arise from this model. The model contains some significant deficiencies, but, as we will show, also represents a significant advance over older, simpler models of fragmentation. 504b030414000600080000002100828abc13fa0000001c020000130000005b436f6e74656e745f54797065735d2e78

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

28

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

PubMed Central

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

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

2003-01-01

29

Implementing integrated rural tourism: An event-based approach  

Microsoft Academic Search

In the past two decades, community involvement in local policy-making has gained increasing attention as an alternative approach to rural development in the European Union (EU), particularly in the context of the complementary sectors of agriculture such as tourism. Although there is a wide range of integrated approaches to tourism development in rural areas identified in the literature, the event-based

Emese Panyik; Carlos Costa; Tamara Rátz

2011-01-01

30

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

31

Event based indexing of broadcasted sports video by intermodal collaboration  

Microsoft Academic Search

In this paper, we propose event-based video indexing, which is a kind of indexing by its semantical contents. Because video data is composed of multimodal information streams such as visual, auditory, and textual [closed caption (CC)] streams, we introduce a strategy of intermodal collaboration, i.e., collaborative processing taking account of the semantical dependency between these streams. Its aim is to

Noboru Babaguchi; Yoshihiko Kawai; Tadahiro Kitahashi

2002-01-01

32

Structure and tribological properties of amorphous carbon films deposited by electrochemical method on GCr15 steel substrate  

Microsoft Academic Search

Amorphous carbon films were deposited on GCr15 steel substrates by electrolysis of methanol, dimethylsulfoxide (DMSO) and the methanol–DMSO intermixture electrolytes, respectively, under high voltage and low temperature conditions. The microstructure and wear morphology of the deposited films were analyzed using X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM) combined with energy dispersive X-ray fluorescence spectrometer (EDX), respectively. The

Qun-feng Zeng; Guang-neng Dong; You-bai Xie

2008-01-01

33

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

NASA Astrophysics Data System (ADS)

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

Saganti, Premkumar

34

GCR neon isotopic abundances: Comparison with wolf-rayet star models and meteoritic abundances  

NASA Astrophysics Data System (ADS)

Measurements of the neon isotopic abundances from the ACE-CRIS experiment are presented. These abundances have been obtained in seven energy intervals over the energy range of ~80<=E<=280 MeV/nucleon. The 22Ne/20Ne source ratio is derived using the measured 21Ne/20Ne abundance as a ``tracer'' of secondary production of the neon isotopes. We find that the 22Ne/20Ne abundance ratio at the cosmic-ray source is a factor of 5.0+/-0.2 greater than in the solar wind. The GCR 22Ne/20Ne ratio is also shown to be considerably larger than that found in anomalous cosmic rays, solar energetic particles, most meteoritic samples of matter, and interplanetary dust particles. Recent two-component Wolf-Rayet models provide predictions for the 22Ne/20Ne ratio and other isotope ratios. Comparison of the CRIS neon, iron, and nickel isotopic source abundance ratios with predictions indicate possible enhanced abundances of some neutron-rich nuclides that are expected to accompany the 22Ne excess. .

Binns, W. R.; Wiedenbeck, M. E.; Christian, E. R.; Cummings, A. C.; George, J. S.; Israel, M. H.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; von Rosenvinge, T. T.; Yanasak, N. E.

2001-11-01

35

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

SciTech Connect

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

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

1989-04-20

36

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

37

Improving Contact Realism through Event-Based Haptic Feedback  

Microsoft Academic Search

Tapping on surfaces in a typical virtual environment 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 position-based feedback. When scaled by impact velocity, hand-tuned pulses and decaying sinusoids produce haptic cues that resemble those experienced during real impacts. Our new

Katherine J. Kuchenbecker; Jonathan Fiene; Günter Niemeyer

2006-01-01

38

Event-based Spatio-temporal Database Design  

Microsoft Academic Search

Both structural and behavioral aspects need to be modeled in some spatio-temporal databases. There existing initial efforts to represent behavioral aspects of the spatio-temporal applications via events gave their priority to some local or partial behaviors rather than an overview of the system's behavior. In this paper, an event-based approach is proposed for modeling the system's behavior of the spatio-temporal

Jun CHEN; Jie JIANG

39

Event-Based Science: Remote-Sensing Activities  

NSDL National Science Digital Library

These activities enable students to use remotely-sensed data- as they tackle the real-world problems and tasks found in existing Event-Based Science (EBS) modules. Remotely-sensed data are employed as an integral part of both the presentation of Earth system science concepts, and in the solutions to real-world problems. The activities emphasize the use of NASA remote-sensing data from satellites and sensors including: Landsat, GOES, and MODIS, and SeaWiFS. The EBS remote-sensing activities enhance EBS modules, including: Blight! Earthquake! Fire! Flood! Hurricane! Oil Spill! and Volcano!

2011-01-01

40

An Event-Based Approach for Semantic Metadata Interoperability  

NASA Astrophysics Data System (ADS)

This paper presents a method for making metadata conforming to heterogeneous schemas semantically interoperable. The idea is to make the knowledge embedded in the schema structures interoperable and explicit by transforming the schemas into a shared, event-based representation of knowledge about the real world. This enables and simplifies accurate reasoning services such as cross-domain semantic search, browsing, and recommending. A case study of transforming three different schemas and datasets is presented. An implemented knowledge-based recommender system utilizing the results in the semantic portal CultureSampo was found useful in a preliminary user study.

Ruotsalo, Tuukka; Hyvönen, Eero

41

Event-based Simulation Model for Quantum Optics Experiments  

SciTech Connect

We present a corpuscular simulation model of optical phenomena that does not require the knowledge of the solution of a wave equation of the whole system and reproduces the results of Maxwell's theory by generating detection events one-by-one. The event-based corpuscular model gives a unified description of multiple-beam fringes of a plane parallel plate and single-photon Mach-Zehnder interferometer, Wheeler's delayed choice, photon tunneling, quantum eraser, two-beam interference, double-slit, Einstein-Podolsky-Rosen-Bohm and Hanbury Brown-Twiss experiments. We also discuss the possibility to refute our corpuscular model.

De Raedt, H. [Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747 AG Groningen (Netherlands); Michielsen, K. [Institute for Advanced Simulation, Juelich Supercomputing Centre, Research Centre Juelich, D-52425 Juelich (Germany)

2011-03-28

42

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

PubMed Central

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

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

2013-01-01

43

A 3D Monte Carlo model of radiation affecting cells, and its application to neuronal cells and GCR irradiation  

NASA Astrophysics Data System (ADS)

A 3D Monte Carlo model of radiation transport in matter is applied to study the effect of heavy ion radiation on human neuronal cells. Central nervous system effects, including cognitive impairment, are suspected from the heavy ion component of galactic cosmic radiation (GCR) during space missions. The model can count, for instance, the number of direct hits from ions, which will have the most affect on the cells. For comparison, the remote hits, which are received through ?-rays from the projectile traversing space outside the volume of the cell, are also simulated and their contribution is estimated. To simulate tissue effects from irradiation, cellular matrices of neuronal cells, which were derived from confocal microscopy, were simulated in our model. To produce this realistic model of the brain tissue, image segmentation was used to identify cells in the images of cells cultures. The segmented cells were inserted pixel by pixel into the modeled physical space, which represents a volume of interacting cells with periodic boundary conditions (PBCs). PBCs were used to extrapolate the model results to the macroscopic tissue structures. Specific spatial patterns for cell apoptosis are expected from GCR, as heavy ions produce concentrated damage along their trajectories. The apoptotic cell patterns were modeled based on the action cross sections for apoptosis, which were estimated from the available experimental data. The cell patterns were characterized with an autocorrelation function, which values are higher for non-random cell patterns, and the values of the autocorrelation function were compared for X rays and Fe ion irradiations. The autocorrelation function indicates the directionality effects present in apoptotic neuronal cells from GCR.

Ponomarev, Artem; Sundaresan, Alamelu; Kim, Angela; Vazquez, Marcelo E.; Guida, Peter; Kim, Myung-Hee; Cucinotta, Francis A.

44

Local and nonlocal geometry of interplanetary coronal mass ejections: Galactic cosmic ray (GCR) short-period variations and magnetic field modeling  

NASA Astrophysics Data System (ADS)

Energetic galactic cosmic ray (GCR) particles, arriving within the solar system, are modulated by the overall interplanetary field carried in the solar wind. Localized disturbances related to solar activity cause further reduction in intensity, the largest being Forbush decreases in which fluxes can fall ˜20% over a few days. Understanding Forbush decreases leads to a better understanding of the magnetic field structure related to shock waves and fast streams originating at the Sun since the propagation characteristics of the GCR probe much larger regions of space than do individual spacecraft instruments. We examined the temporal history of the integral GCR fluence (?100 MeV) measured by the high-sensitivity telescope (HIST) aboard the Polar spacecraft, along with the solar wind magnetic field and plasma data from the ACE spacecraft during a 40-day period encompassing the 25 September 1998 Forbush decrease. We also examined the Forbush and (energetic storm particles) ESP event on 28 October 2003. It is the use of HIST in a high-counting-rate integral mode that allows previously poorly seen, short-scale depressions in the GCR fluxes to be observed, adding crucial information on the origin of GCR modulation. Variability on time scales within the frequency range 0.001-1.0 mHz is detected. This paper concentrates on investigating four simple models for explaining short-term reductions in the GCR intensity of both small and large amplitude. Specifically, these models are a local increase in magnetic scattering power, the passage of a shock discontinuity, and the passage of a tangential discontinuity or magnetic rope in the solar wind plasma. Analysis of the short-scale GCR depressions during a test period in September through October 1998 shows that they are not correlated with changes in magnetic scattering power or fluctuations in solar wind speed or plasma density. However, magnetic field and plasma data during the test period of Forbush decrease strongly suggest the presence of an interplanetary coronal mass ejection (ICME). Use of a non-force-free magnetic rope model in conjunction with the energetic particle data allows modeling of the geometry of the ICME in terms of a magnetic cloud topology. It is only this cloud configuration that allows a satisfactory explanation of the magnitude of the Forbush event of 25 September 1998. Calculations made during the test period point to short-scale GCR depressions being caused by either small-scale magnetic flux rope structures or possibly tangential discontinuities in the solar wind.

Quenby, J. J.; Mulligan, T.; Blake, J. B.; Mazur, J. E.; Shaul, D.

2008-10-01

45

Blackout!: An Event-Based Science Module. Student Edition. Electricity and Solar Activity 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.

46

Blackout!: An Event-Based Science Module. Teacher's Guide. Electricity and Solar Activity 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.

47

Hurricane! An Event-Based Science Module. Student Edition. Meteorology 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.

48

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.

49

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.

50

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

ERIC Educational Resources Information Center

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

Wright, Russell G.

51

Blackout!: An Event-Based Science Module. Teacher's Guide. Electricity and Solar Activity 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.

52

Blackout!: An Event-Based Science Module. Student Edition. Electricity and Solar Activity 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.

53

Survive?: An Event-Based Science Module. Student Edition. Animals and Adaptation 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.

54

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.

55

Tornado! 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 tornadoes 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.

56

Tornado! An Event-Based Science Module. Student Edition. Meteorology 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.

57

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

Microsoft Academic Search

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

Armin Beer; Matthias Heindl

2007-01-01

58

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

59

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.

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

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.

62

Tornado! 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 tornadoes 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.

63

Hurricane! An Event-Based Science Module. Student Edition. Meteorology 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.

64

Earthquake!: An Event-Based Science Module. Teacher's Guide. Earth Science Module.  

ERIC Educational Resources Information Center

This book is designed for middle school earth science teachers to help their students learn about earthquakes 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, teamwork,…

Wright, Russell G.

65

Volcano!: An Event-Based Science Module. Student Edition. Geology Module.  

ERIC Educational Resources Information Center

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

Wright, Russell G.

66

Toxic Leak!: An Event-Based Science Module. Student Edition. Groundwater Module.  

ERIC Educational Resources Information Center

This book is designed for the 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.

67

Tornado! An Event-Based Science Module. Student Edition. Meteorology 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.

68

Earthquake!: An Event-Based Science Module. Student Edition. Earth Science 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.

69

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.

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

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

72

Flood!: An Event-Based Science Module. Student Edition. Stream Dynamics 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.

73

Volcano!: An Event-Based Science Module. Student Edition. Geology 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.

74

Blight! An Event-Based Science Module. Student Edition. Plants and Plant Diseases 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.

75

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.

76

Earthquake!: An Event-Based Science Module. Student Edition. Earth Science 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

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

ERIC Educational Resources Information Center

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

Wright, Russell G.

78

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

79

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.

80

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.

81

Earthquake!: An Event-Based Science Module. Teacher's Guide. Earth Science Module.  

ERIC Educational Resources Information Center

|This book is designed for middle school earth science teachers to help their students learn about earthquakes 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, teamwork,…

Wright, Russell G.

82

Flood!: An Event-Based Science Module. Student Edition. Stream Dynamics 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.

83

Friction and Wear Behavior of UltraHigh Molecular Weight Polyethylene Sliding Against GCr15 Steel and Electroless Ni–P Alloy Coating Under the Lubrication of Seawater  

Microsoft Academic Search

The friction and wear behavior of ultra-high molecular weight polyethylene (UHMWPE) sliding against GCr15 steel and electroless\\u000a Ni-P alloy coating under the lubrication of seawater was investigated and compared with that under dry sliding and lubrication\\u000a of pure water and 3.5 wt.% NaCl solution, respectively. It was found that under the lubrication of aqueous medium, the friction\\u000a and wear behavior of

Jianzhang Wang; Fengyuan Yan; Qunji Xue

2009-01-01

84

Membrane glucocorticoid receptors (mGCR) are expressed in normal human peripheral blood mononuclear cells and up-regulated after in vitro stimulation and in patients with rheumatoid arthritis.  

PubMed

Glucocorticoids mediate their therapeutic actions mostly by genomic effects via cytosolic receptors, but some effects are too rapid to be mediated by changes at the genomic level. The detailed mechanisms of these nongenomic actions are still unclear. Membrane-bound glucocorticoid receptors (mGCR) have been suggested to be involved, although their physiological existence in humans so far is hypothetical. For the first time we demonstrate the existence of mGCR on monocytes and B cells obtained from healthy blood donors using high-sensitivity immunofluorescent staining. Immunostimulation with lipopolysaccharide increases the percentage of mGCR-positive monocytes, which can be prevented by inhibiting the secretory pathway. Overexpression of the human glucocorticoid receptor alpha alone is not sufficient to enhance mGCR expression. These in vitro findings are consistent with our clinical observation that in patients with rheumatoid arthritis the frequency of mGCR positive monocytes is increased and positively correlated with disease activity. We conclude that mGCR are 1) indeed physiologically present in healthy blood donors, but remained unidentified by conventional techniques due to their small number per cell and 2) actively up-regulated and transported through the cell after immunostimulation. These receptors may reflect a feedback mechanism of the organism upon immunostimulation and/or play a role in pathogenesis. PMID:14718388

Bartholome, Burkhard; Spies, Cornelia M; Gaber, Timo; Schuchmann, Sebastian; Berki, Timea; Kunkel, Désirée; Bienert, Maren; Radbruch, Andreas; Burmester, Gerd-Rüdiger; Lauster, Roland; Scheffold, Alexander; Buttgereit, Frank

2004-01-01

85

Model-Based Autosynthesis of Time-Triggered Buffers for Event-Based Middleware Systems  

Microsoft Academic Search

Application developers utilizing event-based middleware have sought to leverage domain-specic modeling for the advan- tages of intuitive specication, code synthesis, and support for design evolution, among other benets. For cyber-physical systems, the use of event-based middleware may result, for some applications, in a need for additional time-based blocks that were not initially considered during system design. An advantage of domain-specic

Jonathan Sprinkle; Brandon Eames

86

Event-based intelligent control of saturated chemical plant using an endomorphic neural network model  

Microsoft Academic Search

An event-based control system with an endomorphic neural network model is designed and realized to control a saturated non-linear plant. The scheme employed in this system is based on an event-based control paradigm previously proposed to control monotonic plants. However, this scheme is different from the previous one in that it can be used to control plants with saturation property.

SUNG HOON JUNG; TAG GON KIM; KYU HO PARK

1995-01-01

87

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

2012-02-09

88

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

PubMed Central

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

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

2011-01-01

89

Introducing numerical bounds to improve event-based neural network simulation  

Microsoft Academic Search

Abstract: Although the spike-trains in neural networks are mainly constrained by the neural dynamics itself, global temporal constraints (r efractoriness, time precision, propagation delays, ..) are also to be taken into account. Th ese constraints are revisited in this paper in order to use them in event-based simulation paradigms. We first review these constraints, and discuss their consequ ences at

Bruno Cessac; Olivier Rochel; Thierry Viéville

2008-01-01

90

Hybrid system model for event-based planning and control of robot operations  

Microsoft Academic Search

This paper presents an event-based hybrid system approach for the motion planning and control of mobile robot systems. The ability of dealing with unexpected events is one of the important aspects of robot intelligence. Robotic systems can obtain environmental information from sensors and respond to environmental information by making task decisions. According to the task decisions, the system is able

Yu Sunt; Jindong Tan; Ning Xi

2003-01-01

91

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

ERIC Educational Resources Information Center

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

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

2007-01-01

92

Challenges to Industry Adoption of the IEC 61499 Standard on Event-based Function Blocks  

Microsoft Academic Search

The IEC 61499 standard on event-based function blocks was adopted between 2003 and 2005. Even considering this relatively recent acceptance as a standard, adoption by the major control system equipment vendors has been slow to nonexistent. This paper examines some of the challenges that must be met to encourage more active use and support for IEC 61499 function blocks. Some

Kenwood H. Hall; Raymond J. Staron; Alois Zoitl

2007-01-01

93

Reference adaptive impedance control: a new paradigm for event-based robotic and telerobotic control  

Microsoft Academic Search

A new paradigm of event-based robotic and telerobotic control, referred to here as the reference adaptive impedance control, is presented for partially constrained robotic and telerobotic tasks under uncertain or unknown environmental constraints. The reference adaptive impedance control determines the desired next state adaptively, in such a way as to follow the optimal path from the current state, where the

Sukhan Lee; Ming-Feng Jean; Jong-Oh Park; Chong-Won Lee

1997-01-01

94

Reference adaptive impedance control: a new paradigm for event-based robotic and telerobotic control  

Microsoft Academic Search

A new paradigm of event-based robotic and telerobotic control, referred to as the reference adaptive impedance control, is presented for partially constrained robotic and telerobotic tasks under uncertain or unknown environmental constraints. The reference adaptive impedance control determines the desired next state adaptively to follow the optimal path from the current state, where the optimal path is generated with the

Sukhan Lee; Ming-Feng Jean; Jong-Oh Park; Chong-Won Lee

1998-01-01

95

A discrete event-based simulation model for real-time traffic management in railways  

Microsoft Academic Search

Rail systems are highly complex and their control requires mathematical-computational tools. The main drawback of the models used to represent railway traffic, and to resolve any conflicts that occur, is the large computational time needed to obtain satisfactory results. Therefore the purpose of this paper is to study and design a discrete event-based model characterized by the positioning of trains

Jose L. Espinosa; Ricardo García-Ródenas

2012-01-01

96

The JEDI Event-Based Infrastructure and Its Application to the Development of the OPSS WFMS  

Microsoft Academic Search

The development of complex distributed systems demands for the creation of suitable architectural styles (or paradigms) and related run-time infrastructures. An emerging style that is receiving increasing attention is based on the notion of event. In an event-based architecture, distributed software components interact by generating and consuming events. An event is the occu r- rence of some state change in

Gianpaolo Cugola; Elisabetta Di Nitto; Alfonso Fuggetta

2001-01-01

97

An Event-Based Data Distribution Mechanism for Collaborative Mobile Augmented Reality and Virtual Environments  

Microsoft Academic Search

The full power of mobile augmented and virtual real- ity systems is realized when these systems are connected to one another, to immersive virtual environments, and to re- mote information servers. Connections are usually made through wireless networks. However, wireless networks cannot guarantee connectivity and their bandwidth can be highly constrained. In this paper we present a robust event- based

Dennis Brown; Simon Julier; Yohan Baillot; Mark A. Livingston

2003-01-01

98

Local Feature Trajectories for Efficient Event-Based Indexing of Video Sequences  

Microsoft Academic Search

We address the problem of indexing video sequences accord- ing to the events they depict. While a lot's of dierent approaches have been proposed in order to describe events, none is suciently generic and computationally ecient to be applied to event-based retrieval of video sequences within large databases. In this paper, we propose a novel index of video sequences which

Nicolas Moënne-loccoz; Eric Bruno; Stéphane Marchand-maillet

2006-01-01

99

Use of unstructured event-based reports for global infectious disease surveillance.  

PubMed

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

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

2009-05-01

100

Event Based Simulator for Parallel Computing over the Wide Area Network for Real Time Visualization  

NASA Astrophysics Data System (ADS)

As the computational requirement of applications in computational science continues to grow tremendously, the use of computational resources distributed across the Wide Area Network (WAN) becomes advantageous. However, not all applications can be executed over the WAN due to communication overhead that can drastically slowdown the computation. In this paper, we introduce an event based simulator to investigate the performance of parallel algorithms executed over the WAN. The event based simulator known as SIMPAR (SIMulator for PARallel computation), simulates the actual computations and communications involved in parallel computation over the WAN using time stamps. Visualization of real time applications require steady stream of processed data flow for visualization purposes. Hence, SIMPAR may prove to be a valuable tool to investigate types of applications and computing resource requirements to provide uninterrupted flow of processed data for real time visualization purposes. The results obtained from the simulation show concurrence with the expected performance using the L-BSP model.

Sundararajan, Elankovan; Harwood, Aaron; Kotagiri, Ramamohanarao; Satria Prabuwono, Anton

101

Membrane glucocorticoid receptors (mGCR) are expressed in normal human peripheral blood mononuclear cells and up-regulated after in vitro stimulation and in patients with rheumatoid arthritis  

Microsoft Academic Search

Glucocorticoids mediate their therapeutic actions mostly by genomic effects via cytosolic receptors, but some effects are too rapid to be mediated by changes at the genomic level. The detailed mechanisms of these nongenomic actions are still unclear. Membrane-bound glucocorticoid receptors (mGCR) have been suggested to be involved, although their physiological existence in humans so far is hypothetical. For the first

BURKHARD BARTHOLOME; CORNELIA M. SPIES; TIMO GABER; SEBASTIAN SCHUCHMANN; TIMEA BERKI; DESIREE KUNKEL; MAREN BIENERT; ANDREAS RADBRUCH; GERD-RUDIGER BURMESTER; ROLAND LAUSTER; ALEXANDER SCHEFFOLD; FRANK BUTTGEREIT

2004-01-01

102

Event-Based Planning and Control for Multi-Robot Coordination  

Microsoft Academic Search

A planning and control scheme for multi-robot coordination is presented. An event-based motion reference that drives the system to achieve the best possible coordination is introduced. The general task space is combined with the nonlinear feedback technique to design hybrid position\\/force controllers. To improve the force control performance, the dynamics of joint motors are taken into account. For a given

Ning Xi; Tzyh Jong Tarn; Antal K. Bejczy

1993-01-01

103

Event-based 64-channel binaural silicon cochlea with Q enhancement mechanisms  

Microsoft Academic Search

This paper describes an event-based binaural silicon cochlea aimed at spatial audition and auditory scene analysis. The chip has a matched pair of 64-stage cascaded analog second-order filter banks with 512 pulse-frequency modulated (PFM) address-event representation (AER) outputs. The spectral selectivity is sharpened through 2 different on-chip methods: an on-chip local Q DAC and an on-chip spatial sharpening through nearest

Shih-Chii Liu; André van Schaik; Bradley A. Minch; Tobi Delbrück

2010-01-01

104

An event-based approach for comparing the performance of methods for prospective medical product monitoring  

PubMed Central

Prospective medical product monitoring is intended to alert stakeholders about whether and when safety problems are identifiable in a continuous stream of longitudinal electronic healthcare data. In comparing the performance of methods to generate these alerts, three factors must be considered: (1) accuracy in alerting; (2) timeliness of alerting; and (3) the trade-offs between the costs of false negative and false positive alerting. Using illustrative examples, we show that traditional scenario-based measures of accuracy, such as sensitivity and specificity, which classify only at the end of monitoring, fail to appreciate timeliness of alerting. We propose an event-based approach that classifies exposed outcomes according to whether or not a prior alert was generated. We provide event-based extensions to existing metrics and discuss why these metrics are limited in this setting because of inherent tradeoffs that they impose between the relative consequences of false positives versus false negatives. We provide an expression that summarizes event-based sensitivity (the proportion of exposed events that occur after alerting among all exposed events in scenarios with true safety issues) and event-based specificity (the proportion of exposed events that occur in the absence of alerting among all exposed events in scenarios with no true safety issues) by taking an average weighted by the relative costs of false positive and false negative alerting. This approach explicitly accounts for accuracy in alerting, timeliness in alerting, and the trade-offs between the costs of false negative and false positive alerting. Subsequent work will involve applying the metric to simulated data.

Gagne, Joshua J.; Walker, Alexander M.; Glynn, Robert J.; Rassen, Jeremy A.; Schneeweiss, Sebastian

2012-01-01

105

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

106

Event-based Transmission Line Matrix Method for Simulating Site-Specific Multipath Propagation Characteristics  

SciTech Connect

Accurate radio channel modeling is essential for deploying advanced wireless sensors in harsh industrial and urban environments. Site-specific propagation modeling tools are required to understand the channel parameters with in these environments. Multipath delay spread determines the frequency-selective fading characteristics of the channel. This paper describes a novel computationally inexpensive technique to determine multipath delay spread. Event-based transmission line matrix-based method is used to simulate the channel.

Kuruganti, Phani Teja [ORNL; Nutaro, James J [ORNL; Djouadi, Seddik M [ORNL

2012-01-01

107

Qualitative Event-Based Expert Supervision Part 2: Distillation Start-up Condition Monitoring  

Microsoft Academic Search

The solutions to supervise start-up and shut-down operations in close loop are suitable for large industrial systems. Similarly, the batch and semi-continuous processes in order to maintain the operation in a dynamic mode. This paper considers the qualitative event-based expert supervision approach of these problems of a distillation column. The development of a general supervision in this work is based

Flávio Neves Jr.; Joseph Aguilar-martin

1998-01-01

108

Visual field index rate and event-based glaucoma progression analysis: comparison in a glaucoma population  

Microsoft Academic Search

Aims:The aim of the study was to compare event-based glaucoma progression analysis (GPA) I with new GPA II software and pattern deviation-based trend analyses (visual field index [VFI]) to detect progression in a glaucoma population.Methods:This was a retrospective study that included 90 eyes of 90 patients with a minimum of five reliable visual field tests and a follow-up period of

P Casas-Llera; G Rebolleda; F J Muñoz-Negrete; F Arnalich-Montiel; M Pérez-López; R Fernández-Buenaga

2009-01-01

109

Forgetting at short term: when do event-based interference and temporal factors have an effect?  

PubMed

Memory tasks combining storage and distracting tasks performed at either encoding or retrieval have provided divergent results pointing towards accounts of forgetting in terms of either temporal decay or event-based interference respectively. The aim of this study was to shed light on the possible sources of such a divergence that could rely on methodological aspects or deeper differences in the memory traces elicited by the different paradigms used. Methodological issues were explored in a first series of experiments by introducing at retrieval computer-paced distracting tasks that involved articulatory suppression, attentional demand, or both. A second series of experiments that used a similar design was intended to induce differences in the nature of memory traces by increasing the time allowed for encoding the to-be-remembered items. Although the introduction of computer-paced distracting tasks allowed for a strict control of temporal parameters, the first series of experiments replicated the effects usually attributed to event-based interference. However, deeper encoding abolished these effects while time-related effects remained unchanged. These findings suggest that the interplay between temporal factors and event-based interference in forgetting at short term is more complex than expected and could depend on the nature of memory traces. PMID:23337080

Barrouillet, Pierre; Plancher, Gaën; Guida, Alessandro; Camos, Valérie

2013-01-19

110

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

NASA Astrophysics Data System (ADS)

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 two anthropomorphic phantoms (a mathematical model and a “voxel” model) to calculate organ-averaged dose, dose equivalent and “biological dose” in the various tissues and organs following exposure to the August 1972 Solar Particle Event and to Galactic Cosmic Rays under different shielding conditions. The “biological dose” was characterized by the average number of induced “Complex Lesions” (CLs) per cell in a given organ or tissue, where CLs are clustered DNA breaks which can play an important role in chromosome aberration induction. Separate calculation of the contributions from secondary hadrons in particular neutrons with respect to primary particles allowed us to quantify the role played by nuclear interactions occurring in the shield and in the human body. Specifically for GCR, the contributions from the different components of the incident primary spectra were calculated separately as well. As expected, the SPE doses showed a dramatic decrease with increasing Al shielding. Furthermore, for SPEs internal organs received much lower doses with respect to skin, and nuclear interactions were found to be of minor importance. A 10 g/cm2 Al storm shelter turned out to be sufficient to respect the NCRP limits for 30-days LEO missions in case of a SPE similar to the August 1972 event. In contrast with SPEs, GCR absorbed doses remained roughly constant with increasing Al shielding. The organ-averaged dose equivalent and biological dose showed a (slight) decrease starting from a shield thickness of 2 g/cm2, probably due the lower LET of projectile fragments.

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

111

Event-based size distributions of particulate matter transported during urban rainfall-runoff events.  

PubMed

Source area rainfall-runoff conveyances are capable of mobilizing and transporting a very hetero-disperse size gradation of particulate matter (PM). This PM is most commonly characterized through a single event-based gravimetric index such as total suspended solids (TSS) or suspended sediment concentration (SSC) without an examination of PM fractions or particle size distributions (PSDs). Recognizing the utility of such indices, this study went further to examine PM suspended-settleable-sediment fractions and PSDs to representatively characterize the entire event-based PSD of the PM non-colloidal fractions from 1 microm to larger than 24,500 microm transported by urban source area runoff events. This study examined the hetero-disperse PSD, and provided a mass balance analysis to ensure representative event-based results. On an event basis, fine PM (<75 microm; the suspended and settleable fractions) accounted for from 25% to 80% of the gradation on a mass basis, and gravel-size PM (>2000 microm) ranged from 0.5% to 30%. Measured PSDs were compared to literature PSDs on paved surfaces, and in urban runoff from paved surfaces as well as the associated sampling and analysis methods. Results indicate that published urban street surface PSDs are generally within a similar range, with wider variability for published runoff PSDs. PSD variability is attributed to differences in sampling and analytical methods between studies. Knowledge of PSDs is critical for PM transport and fate, pollutant partitioning and distribution, as well as the non-stationary behavior of unit operations. PMID:18342357

Kim, Jong-Yeop; Sansalone, John J

2008-02-17

112

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

PubMed Central

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

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

2010-01-01

113

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

114

Event-based plausibility immediately influences on-line language comprehension.  

PubMed

In some theories of sentence comprehension, linguistically relevant lexical knowledge, such as selectional restrictions, is privileged in terms of the time-course of its access and influence. We examined whether event knowledge computed by combining multiple concepts can rapidly influence language understanding even in the absence of selectional restriction violations. Specifically, we investigated whether instruments can combine with actions to influence comprehension of ensuing patients of (as in Rayner, Warren, Juhuasz, & Liversedge, 2004; Warren & McConnell, 2007). Instrument-verb-patient triplets were created in a norming study designed to tap directly into event knowledge. In self-paced reading (Experiment 1), participants were faster to read patient nouns, such as hair, when they were typical of the instrument-action pair (Donna used the shampoo to wash vs. the hose to wash). Experiment 2 showed that these results were not due to direct instrument-patient relations. Experiment 3 replicated Experiment 1 using eyetracking, with effects of event typicality observed in first fixation and gaze durations on the patient noun. This research demonstrates that conceptual event-based expectations are computed and used rapidly and dynamically during on-line language comprehension. We discuss relationships among plausibility and predictability, as well as their implications. We conclude that selectional restrictions may be best considered as event-based conceptual knowledge rather than lexical-grammatical knowledge. PMID:21517222

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

2011-07-01

115

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

116

Event-based motion correction for PET transmission measurements with a rotating point source  

NASA Astrophysics Data System (ADS)

Accurate attenuation correction is important for quantitative positron emission tomography (PET) studies. When performing transmission measurements using an external rotating radioactive source, object motion during the transmission scan can distort the attenuation correction factors computed as the ratio of the blank to transmission counts, and cause errors and artefacts in reconstructed PET images. In this paper we report a compensation method for rigid body motion during PET transmission measurements, in which list mode transmission data are motion corrected event-by-event, based on known motion, to ensure that all events which traverse the same path through the object are recorded on a common line of response (LOR). As a result, the motion-corrected transmission LOR may record a combination of events originally detected on different LORs. To ensure that the corresponding blank LOR records events from the same combination of contributing LORs, the list mode blank data are spatially transformed event-by-event based on the same motion information. The number of counts recorded on the resulting blank LOR is then equivalent to the number of counts that would have been recorded on the corresponding motion-corrected transmission LOR in the absence of any attenuating object. The proposed method has been verified in phantom studies with both stepwise movements and continuous motion. We found that attenuation maps derived from motion-corrected transmission and blank data agree well with those of the stationary phantom and are significantly better than uncorrected attenuation data.

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

2011-05-01

117

Event-based Plausibility Immediately Influences On-line Language Comprehension  

PubMed Central

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

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

2011-01-01

118

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

PubMed Central

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

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

2010-01-01

119

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

NASA Astrophysics Data System (ADS)

Astronauts' exposure to space radiation is of major concern for long-term missions, especially for those in deep space such as a possible mission to Mars. Shielding optimization is therefore a crucial issue, and simulations based on radiation transport codes coupled with anthropomorphic model phantoms can be of great help. In this work, carried out with the FLUKA MC code and two anthropomorphic phantoms (a mathematical model and a "voxel" model), distributions of physical (i.e. absorbed), equivalent and "biological" dose in the various tissues and organs were calculated in different shielding conditions for solar minimum and solar maximum GCR spectra, as well as for the August 1972 Solar Particle Event. The biological dose was modeled as the average number of "Complex Lesions" (CL) per cell in a given organ. CLs are clustered DNA breaks previously calculated with "event-by-event" track structure simulations and integrated in the condensed-history FLUKA code. This approach is peculiar in that it is an example of a mechanistically-based quantification of the ionizing radiation action in biological targets; indeed CLs have been shown to play a fundamental role in chromosome aberration induction. The contributions of primary particles and secondary hadrons were calculated separately, thus allowing quantification of the role of nuclear reactions in the shield and in the human body. As expected, the doses calculated for the 1972 SPE decrease dramatically with increasing the Al shielding; nuclear reactions were found to be of minor importance, although their role is higher for internal organs and large shielding. An Al shield thickness of 10 g/cm2 appears sufficient to respect the 30-day deterministic limits recommended by NCRP for missions in Low Earth Orbit. In contrast with the results obtained for SPE, GCR doses to internal organs are not significantly lower than skin doses. However, the relative contribution of secondary hadrons was found to be more important for internal organs due to nuclear interactions in the human body. Both for skin and for internal organs, the physical dose was found to be essentially independent of the shield thickness. The equivalent and biological doses to skin show a significant decrease starting from 5 g/cm2, whereas internal organs show more complex trends characterized by minima and maxima mainly dependent on the organ type. Polyethylene shielding resulted to be more effective with respect to Aluminum.

Ballarini, F.; Fluka-Phantoms Team

120

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

NASA Astrophysics Data System (ADS)

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

Giorgio, Massimiliano; Greco, Roberto

2010-05-01

121

EQRM: An open-source event-based earthquake risk modeling program  

NASA Astrophysics Data System (ADS)

Geoscience Australia's Earthquake Risk Model (EQRM) is an event-based tool for earthquake scenario ground motion and scenario loss modeling as well as probabilistic seismic hazard (PSHA) and risk (PSRA) modeling. It has been used to conduct PSHA and PSRA for many of Australia's largest cities and it has become an important tool for the emergency management community which use it for scneario response planning. It has the potential to link with earthquake monitoring programs to provide automatic loss estimates from network recorded events. An open-source alpha-release version of the software is freely available on SourceForge. It can be used for hazard or risk analyses in any region of the world by supplying appropriately formatted input files. Source code is also supplied so advanced users can modify individual components to suit their needs.

Robinson, D. J.; Dhu, T.; Row, P.

2007-12-01

122

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

NASA Astrophysics Data System (ADS)

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. Very 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. As a result, tasks for one iteration do not wait for the previous iteration to complete, but are started when the needed data are available. For given convergence properties, the event-based approach relaxes the speed requirements on the coarse solver by a factor of ˜K, where K 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. In addition, the framework used for this implementation executes a task when the data dependencies are satisfied and computational resources are available. This leads to improved computational efficiency over previous approaches that pipeline or schedule groups of tasks to a particular processor or group of processors.

Berry, L. A.; Elwasif, W.; Reynolds-Barredo, J. M.; Samaddar, D.; Sanchez, R.; Newman, D. E.

2012-07-01

123

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

PubMed Central

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

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

2009-01-01

124

Can readers ignore implausibility? Evidence for nonstrategic monitoring of event-based plausibility in language comprehension.  

PubMed

We present evidence for a nonstrategic monitoring of event-based plausibility during language comprehension by showing that readers cannot ignore the implausibility of information even if it is detrimental to the task at hand. In two experiments using a Stroop-like paradigm, participants were required to provide positive and negative responses independent of plausibility in an orthographical task (Experiment 1) or a nonlinguistic color judgment task (Experiment 2) to target words that were either plausible or implausible in their context. We expected a nonstrategic assessment of plausibility to interfere with positive responses to implausible words. ANOVAs and linear mixed models analyses of the response latencies revealed a significant interaction of plausibility and required response that supported this prediction in both experiments, despite the use of two very different tasks. Moreover, it could be shown that the effect was not driven by the differential predictability of plausible and implausible words. These results suggest that plausibility monitoring is an inherent component of information processing. PMID:23165201

Isberner, Maj-Britt; Richter, Tobias

2012-11-17

125

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

126

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

127

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

128

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

129

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

130

A Review of Evaluations of Electronic Event-based Biosurveillance Systems  

PubMed Central

Objective To assess evaluations of electronic event-based biosurveillance systems (EEBS’s) and define priorities for EEBS evaluations. Introduction EEBS’s that use near real-time information from the Internet are an increasingly important source of intelligence for public health organizations (1, 2). However, there has not been a systematic assessment of EEBS evaluations, which could identify uncertainties about current systems and guide EEBS development to effectively exploit digital information for surveillance. Methods We searched PubMed and consulted EEBS experts to identify EEBS’s that met the following criteria: uses publicly-available Internet info sources, includes events that impact humans, and has global scope. We constructed a list of 17 key evaluation variables using guidelines for evaluating health surveillance systems, and identified the key variables included in evaluations per EEBS, as well as the number of EEBS’s evaluated for each key variable (3,4). Results We identified 10 EEBS’s and 17 evaluations (Table 1). The number of evaluations per EEBS ranged from 1 (Gen-Db, GODsN) to 7 (GPHIN, HealthMap). The median number of variables assessed per EEBS was 6 (range, 3–12), with 5 (25%) evaluations assessing 7+ variables. Nine (53%) published evaluations contained quantitative assessments of at least 1 variable. The least-frequently studied variable was cost. No papers examined usefulness as specific public health decisions or outcomes resulting from early event detection, though 8 evaluations assessed usefulness by citing instances where the EEBS detected an outbreak earlier, or by eliciting user feedback. Conclusions While EEBS’s have demonstrated their usefulness and accuracy for early outbreak detection, no evaluations have cited specific examples of public health decisions or outcomes resulting from the EEBS. Future evaluations should discuss these critical indicators of public health utility. They also should assess the novel aspects of EEBS and include variables such as policy readiness, system redundancy, input/output geography (5); and test the effects of combining EEBS’s into a “super system”.

Gajewski, Kimberly; Chretien, Jean-Paul; Peterson, Amy; Pavlin, Julie; Chitale, Rohit

2013-01-01

131

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

132

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

133

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

PubMed Central

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

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

2011-01-01

134

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

PubMed Central

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

2011-01-01

135

Characteristics of suspended solids, microorganisms, and chemical water quality in event-based stormwater runoff from an urban residential area.  

PubMed

Temporal evolution of microbiological, physical, and chemical quality of stormwater runoff from a stormwater drain in an urban residential area in Calgary, Canada, was investigated from May to September, 2006 and 2007. Investigating event mean concentrations and their correlations with rainfall characteristics revealed that intensive rainfall events produced highly polluted stormwater runoff when pollutant source limitation did not occur. Inconsistent event-based correlations between total suspended solids (TSS) concentrations and water quality parameters were observed. During storms, the loading of TSS exhibited a flow-dependent nature, whereas microorganism discharge appeared to be governed by a flow-independent mechanism. No strong first-flush effect was observed in either TSS or microorganisms, on average. No correlations of first-flush loads of TSS with rainfall characteristics were identified. Moderate negative correlations between first-flush loads of microorganisms and rainfall depth and intensity indicated that first flush of microorganisms tended to occur in small storms. PMID:21214027

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

2010-12-01

136

Substance Use and Other Risk Factors for Unprotected Sex: Results From An Event-Based Study of Homeless Youth  

PubMed Central

This study used an event-based approach to understand condom use in a probability sample of 309 homeless youth recruited from service and street sites in Los Angeles County. Condom use was significantly less likely when hard drug use preceded sex, the relationship was serious, the partners talked about “pulling out”, or sex occurred in a non-private place (and marginally less likely when heavier drinking preceded sex, or the partnership was monogamous or abusive). Condom use was significantly more likely when the youth held positive condom attitudes or were concerned about pregnancy, the partners talked about condom use, and the partners met up by chance. This study extends previous work by simultaneously examining a broad range of individual, relationship, and contexual factors that may play a role in condom use. Results identify a number of actionable targets for programs aimed at reducing HIV/STI transmission and pregnancy risk among homeless youth.

Tucker, Joan S.; Ryan, Gery W.; Golinelli, Daniela; Munjas, Brett; Wenzel, Suzanne L.; Kennedy, David P.; Green, Harold D.; Zhou, Annie

2011-01-01

137

Substance use and other risk factors for unprotected sex: results from an event-based study of homeless youth.  

PubMed

This study used an event-based approach to understand condom use in a probability sample of 309 homeless youth recruited from service and street sites in Los Angeles County. Condom use was significantly less likely when hard drug use preceded sex, the relationship was serious, the partners talked about "pulling out", or sex occurred in a non-private place (and marginally less likely when heavier drinking preceded sex, or the partnership was monogamous or abusive). Condom use was significantly more likely when the youth held positive condom attitudes or were concerned about pregnancy, the partners talked about condom use, and the partners met up by chance. This study extends previous work by simultaneously examining a broad range of individual, relationship, and contexual factors that may play a role in condom use. Results identify a number of actionable targets for programs aimed at reducing HIV/STI transmission and pregnancy risk among homeless youth. PMID:21932093

Tucker, Joan S; Ryan, Gery W; Golinelli, Daniela; Ewing, Brett; Wenzel, Suzanne L; Kennedy, David P; Green, Harold D; Zhou, Annie

2012-08-01

138

Addressing the time-scale gap in erosion modelling - comparison of an event-based and a landscape evolution model  

NASA Astrophysics Data System (ADS)

An obvious timescale gap exists between a single storm event and long term landscape development. In this study the event- and physically based OpenLISEM soil erosion model was compared to the landscape evolution model LAPSUS, deliberately extending and shortening the timescales for which each model was developed. Calibration of OpenLISEM using average erosion rates derived from long-term simulations with LAPSUS and, vice versa, calibration of LAPSUS on event-scale did not give satisfactory results, suggesting that the gap between the different timescales of both models is too large to be bridged directly. However, calibration of LAPSUS on annual basis using the summed OpenLISEM erosion and deposition values for each year resulted in a good reproduction of these values by LAPSUS. Thus, when keeping to the timescale that the model was originally intended for, but calibrating the model using simulation results from the event-based model, short-term variability could successfully be introduced in longer-term modelling of landscape development. Subsequently, the erosion effects of rainfall variability, climate and land use change were explored on a centennial timescale. Results show non-linear behaviour between rainfall input and simulated net erosion. Simulated net erosion for increased rainfall erosivity was compared to rainfall variability, showing that mean annual net erosion of up to 15% increased erosivity is not significantly different from annual mean net erosion of the original simulations. Single events must be very high and/or frequent to leave a signal in the landscape that is beyond the scope of natural rainfall variability. Scenarios of human impact show that land use changes can have a potentially larger effect on erosion dynamics than climate variability and change. This is the first time that an event-based erosion model and a landscape evolution model were calibrated for the same area and compared in terms of erosion and deposition dynamics.

Baartman, J. E. M.; Temme, A. J. A. M.; Veldkamp, A.; Jetten, V. G.; Schoorl, J. M.

2012-04-01

139

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

140

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

PubMed

Information regarding the remediation of event-based prospective memory (EB-PM) impairments following pediatric traumatic brain injury (TBI) is scarce. Addressing this, two levels of monetary incentives were used to improve EB-PM in children ages 7 to 16 years with orthopedic injuries (OI, n = 51), or moderate (n = 25) and severe (n = 39) TBI at approximately 3 months postinjury. The EB-PM task consisted of the child giving a specific verbal response to a verbal cue from the examiner while performing a battery of neuropsychological measures (ongoing task). Significant effects were found for age-at-test, motivation condition, period, and group. Within-group analyses indicated that OI and moderate TBI groups performed significantly better under the high- than under the low-incentive condition, but the severe TBI group demonstrated no significant improvement. These results indicate that EB-PM can be significantly improved at 3 months postinjury in children with moderate, but not severe, TBI. PMID:21347945

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

2011-07-01

141

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

PubMed

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

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

2013-03-07

142

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

2012-10-16

143

Benefits and limitations of data assimilation for discharge forecasting using an event-based rainfall-runoff model  

NASA Astrophysics Data System (ADS)

Mediterranean catchments in southern France are threatened by potentially devastating fast floods which are difficult to anticipate. In order to improve the skill of rainfall-runoff models in predicting such flash floods, hydrologists use data assimilation techniques to provide real-time updates of the model using observational data. This approach seeks to reduce the uncertainties present in different components of the hydrological model (forcing, parameters or state variables) in order to minimize the error in simulated discharges. This article presents a data assimilation procedure, the best linear unbiased estimator (BLUE), used with the goal of improving the peak discharge predictions generated by an event-based hydrological model Soil Conservation Service lag and route (SCS-LR). For a given prediction date, selected model inputs are corrected by assimilating discharge data observed at the basin outlet. This study is conducted on the Lez Mediterranean basin in southern France. The key objectives of this article are (i) to select the parameter(s) which allow for the most efficient and reliable correction of the simulated discharges, (ii) to demonstrate the impact of the correction of the initial condition upon simulated discharges, and (iii) to identify and understand conditions in which this technique fails to improve the forecast skill. The correction of the initial moisture deficit of the soil reservoir proves to be the most efficient control parameter for adjusting the peak discharge. Using data assimilation, this correction leads to an average of 12% improvement in the flood peak magnitude forecast in 75% of cases. The investigation of the other 25% of cases points out a number of precautions for the appropriate use of this data assimilation procedure.

Coustau, M.; Ricci, S.; Borrell-Estupina, V.; Bouvier, C.; Thual, O.

2013-03-01

144

Temporal instability of parameters in an event-based distributed hydrologic model applied to a small semiarid catchment  

NASA Astrophysics Data System (ADS)

Event-based hydrologic modeling is common practice for semiarid basins where runoff is restricted to short periods after a storm. Such models are used to predict runoff production and soil erosion in agricultural areas as well as the effects of storms on sewer systems, all in areas with limited information. Sometimes, model parameterization is done through infiltration experiments to obtain a parametric infiltration curve or using standard values in lookup tables associated with land use as it is often the case for hydraulic roughness. The model may then be used to predict soil losses or runoff production in storms of different intensities. In the present study a distributed hydrologic model was calibrated to see if rainfall runoff events of different intensities in a single semiarid basin may have different optimal calibrated sets of parameters. To achieve this, 17 sequential events were calibrated covering a wide range of conditions and storm types in the semiarid southwest of Spain. Two parameters related to roughness (Manning’s n and standard deviation of terrain micro-heights) and three related to infiltration (initial and final infiltration capacities and infiltration decay rate) were calibrated for each event. The results show that the calibrated set of parameters and their sensitivities change through time. The drift of the minima in the parameter space is partially explained by the type of storm. Hydraulic roughness and initial infiltration capacity showed the highest sensitivity to rainfall intensity, while steady state infiltration capacity showed sensitivity to information used as a proxy for the wetness state of the basin. The dynamics of the parameters and their relative sensitivities indicate that the model has to adjust itself to the different conditions of the basin so no single set of parameters characterizes the basin.

Maneta, Marco P.; Pasternack, Gregory B.; Wallender, Wesley W.; Jetten, Victor; Schnabel, Susanne

2007-08-01

145

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

PubMed Central

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

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

2010-01-01

146

Time-based and event-based prospective memory in autism spectrum disorder: the roles of executive function and theory of mind, and time-estimation.  

PubMed

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 intellectually high-functioning children with ASD, and 21 age- and IQ-matched neurotypical comparison children. We found impaired time-based, but undiminished event-based, prospective memory among children with ASD. In the ASD group, time-based prospective memory performance was associated significantly with diminished theory of mind, but not with diminished cognitive flexibility. There was no evidence that time-estimation ability contributed to time-based prospective memory impairment in ASD. PMID:23179340

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

2013-07-01

147

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

Microsoft Academic Search

While event-based prospective memory (EB-PM) tasks are a familiar part of daily life for children, currently no data exists concerning the relation between EB-PM performance and brain volumetrics after traumatic brain injury (TBI). This study investigated EB-PM in children (7 to 17 years) with moderate to severe TBI or orthopedic injuries. Participants performed an EB-PM task and concurrently underwent neuroimaging

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

2010-01-01

148

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

149

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

PubMed Central

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

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

2009-01-01

150

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

PubMed

The present meta-analysis investigated whether event-based prospective memory (PM) age effects differ by task order specificity. In specified PM tasks, the order of the ongoing and the PM task response is predetermined, which imposes demands on cognitive control to navigate the possible response options. In contrast, unspecified PM tasks do not require responding in a particular order. Based on 57 studies and more than 5,500 younger and older adults, results showed larger PM age effects in specified compared with unspecified PM tasks. Additionally, the effect of task focality on age differences was replicated. Results suggest that both pre- and postretrieval processes independently affect PM age effects. (PsycINFO Database Record (c) 2013 APA, all rights reserved). PMID:24041004

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

2013-09-01

151

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

PubMed Central

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

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

2012-01-01

152

Interactive effects in transfer-appropriate processing for event-based prospective memory: The roles of effort, ongoing task, and PM cue properties.  

PubMed

Past studies (e.g., Marsh, Hicks, & Cook Journal of Experimental Psychology: Learning, Memory, and Cognition 31:68-75, 2005; Meiser & Schult European Journal of Cognitive Psychology 20:290-311, 2008) have shown that transfer-appropriate processing (TAP) effects in event-based prospective memory (PM) depend on the effort directed toward the ongoing task. In the present study, we addressed mixed findings from these studies and examined monitoring in TAP and transfer-inappropriate processing (TIP) conditions. In two experiments, a semantic or orthographic ongoing task was paired with a PM cue that either was matched in processing (TAP) or did not match in processing (TIP). Within each condition, effort was varied across trials. The results indicated that PM accuracy was higher in TAP than in TIP conditions, regardless of effort condition, supporting the findings reported by Meiser and Schult. Ex-Gaussian functions were fit to the mean reaction times (cf. Brewer Journal of Psychology 219:117-124, 2011) in order to examine monitoring across conditions. The analysis of distributional skew (? parameter) showed sensitivity to ongoing task instructions and properties of the PM cues. These results support Meiser and Schult's suggestion that TIP conditions require more attentional processing, and they also afford novel discussion on the interactive effects of ongoing task condition, PM cue properties, and manipulations of effort. PMID:23649838

Abney, Drew H; McBride, Dawn M; Petrella, Samantha N

2013-10-01

153

Event based vision sensing and processing  

Microsoft Academic Search

In this paper we briefly summarize the fundamental properties of spike events processing applied to artificial vision systems. This sensing and processing technology is capable of very high speed throughput, because it does not rely on sensing and processing sequences of frames, and because it allows for complex hierarchically structured cortical-like layers for sophisticated processing. The paper describes briefly cortex-like

Jose Antonio Perez-carrasco; Carmen Serrano; Begoña Acha; Teresa Serrano-gotarredona; Bernabé Linares-barranco

2008-01-01

154

An Event-Based Architecture Definition Language  

Microsoft Academic Search

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

David C. Luckham; James Vera

1995-01-01

155

An event-based jet-stream climatology and typology  

NASA Astrophysics Data System (ADS)

A novel climatology is developed for upper-tropospheric jet streams, which is complementary to and an alternative for the traditional depictions of the time-mean jets. It entails identifying the occurrence of a jet event at a given location and then compiling the spatial frequency distribution of such events. The resulting climatology, derived using the ERA-15 reanalysis data set of the ECMWF for the period 1979-1993 indicates that (1) in both hemispheres the annual cycle of jet events takes the form of comparatively smooth transition from a quasi-annular structure in summer to a more spiral-like structure in winter with a temporally asymmetric return to the summer pattern; (2) the hemispheres differ primarily in the amplitude of the frequencies and the longitudinal overlap of the spiral portion of the pattern.In addition, the jet events are subdivided using a two-class typology comprising shallow and deep jets whose vertical shear (sic. baroclinicity) are/are not confined principally to the upper troposphere. This provides a conceptually simple and dynamically meaningful classification since deep jets are more likely to spawn tropospheric-spanning cyclones. The accompanying climatology displays important longitudinal variations and significant inter-hemispheric differences.A comparison is drawn between these new and conventional climatologies and typologies. Also, comments are proffered on the relationship between, on the one hand, the patterns of jet frequency including the differing distributions of the shallow and deep types and, on the other hand, the location of the time-mean jets and the downstream storm tracks.

Koch, Patrick; Wernli, Heini; Davies, Huw C.

2006-03-01

156

An event-based model for interactive live TV shows  

Microsoft Academic Search

Over the years some models for multimedia spatio-temporal synchronization has been proposed. In most of these models, a known drawback is that they generally abstract the media content and consider only start and end events content presentation. Thus, it is not possible to specify synchronization relations involving \\

Manoel Carvalho Marques Neto; Celso A. S. Santos

2008-01-01

157

Event-Based Planning for Standard Polymer Products  

Microsoft Academic Search

In a highly dynamic market environment, the required planning quality for the entire supply chain can increase to such an\\u000a extent that it can be reached with fixed planning cycles only at the very high cost of frequent planning. If demand or the\\u000a raw materials market develops differently from what is anticipated, a readjustment of the entire supply chain becomes

Matthias Lautenschläger

158

The Principle of Immanence in Event-Based Distributed Systems  

Microsoft Academic Search

\\u000a This chapter focuses on the principle of immanence for autonomic eventbased distributed systems such as collaborative environments\\u000a on the GRID. On the one hand, GRID provides a sound infrastructure for coordinating distributed computing resources and Virtual\\u000a Organisations (VO). On the other hand, immanence is a principle that emerges from the internal behaviour of complex systems\\u000a such as social organisations. Although

Pascal Dugenie; Stefano A. Cerri

159

Balboa: A Framework for Event-Based Process Data Analysis  

Microsoft Academic Search

Software process research has suer ed from a lack of focussed data analysis techniques and tools. Part of the problem is the ad hoc and heterogeneous nature of the data, as well as the methods of collecting those data. While collection methods must be specic to their data source, analysis tools should be shielded from specic data formats and idiosyncrasies.

Jonathan E. Cook; Alexander L. Wolf

1998-01-01

160

Event-based Workflow and the Management Interface  

Microsoft Academic Search

Long transactions cause pragmatic problems for workflow systems - as the transaction is moving, so is the surrounding world. We look at three scenarios in which external events affect the performance and public perception of a system. Then we discuss management user interfaces. First, we consider an intervention interface. Second, we argue that a context monitor, manned by humans rather

Jeffrey V. Nickerson

2003-01-01

161

Event-based color change pixel in standard CMOS  

Microsoft Academic Search

This paper describes a novel spiking pixel circuit that reacts to color change but not to intensity change. It is built in standard CMOS without the use of color filters using a buried double junction to sense wavelength information. The pixel can detect light wavelength changes of about 14nm, while not responding to intensity changes of at least a factor

Raphael Berner; Tobi Delbrück

2010-01-01

162

Electronic Event-based Surveillance for Monitoring Dengue, Latin America  

PubMed Central

The current dengue epidemic in Latin America represents a major threat to health. However, surveillance of affected regions lacks timeliness and precision. We investigated real-time electronic sources for monitoring spread of dengue into new regions. This approach could provide timely estimates of changes in distribution of dengue, a critical component of prevention and control efforts.

Keller, Mikaela; Verma, Aman D.; Buckeridge, David L.; Brownstein, John S.

2012-01-01

163

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

164

Contextual reusability metrics for event-based architectures  

Microsoft Academic Search

Component Based Software Engineering has been perceived to have immense reuse potential. This area has evoked wide interest and has led to considerable investment in research and development effort. Most of these investigations have explored internal characteristics of software components such as correctness, reliability, maintainability, modularity, understandability, readability, interoperability, portability, generality and genericity for promoting reuse. But experience over the

Sutirtha Bhattacharya; Dewayne E. Perry

2005-01-01

165

Qualitative Event-Based Expert Supervision for Transient Condition Monitoring  

Microsoft Academic Search

This paper addresses the following supervisory problem: a continuous plant (P) is to be supervised via symbolic (or quantised) actions. These symbolic actions suggest the set points for the lower level control loops. The system dynamic is analysed on the supervisory level (K) by a qualitative approach. The relationships between variables and the steady-state references are known. These problems are

Flávio Neves; Joseph Aguilar-Martin

1999-01-01

166

Qualitative Event-Based Expert Supervision Part 1: Methodology  

Microsoft Academic Search

This contribution addresses the following supervisory problem: a continuous plant (P) is to be supervised via symbolic (or quantised) actions. These symbolic actions suggest the set points to the lower level control loops. The system dynamic is analysed on supervisory level (K) by a qualitative approach. The relationships between variables and the steady-state references are known. These problems are especially

Flávio Neves Jr.; Joseph Aguilar-martin

1998-01-01

167

Home Photo Content Modeling for Personalized Event-Based Retrieval  

Microsoft Academic Search

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

Joo-hwee Lim; Qi Tian; Philippe Mulhem

2003-01-01

168

Integrating Cooperation Systems: An Event-Based Approach  

Microsoft Academic Search

One of today's most challenging problems in office automation is the integration of Workflow Management Systems (WFMS) into legacy systems and their combination with other cooperative applications. For the integration of legacy systems the WFMS provides the central \\

Heiko Ludwig; Klaus Schwab

1995-01-01

169

FENCE to prevent deforestation using an event based sensor network  

Microsoft Academic Search

Research in wireless sensor networks is ongoing at a large scale for applications deployable world-wide like forest monitoring etc. To design, deploy and evaluate novel wireless systems, large and critical application requires a substantial effort. One of the major applications of wireless sensor networks is in event detection. The main objective of this paper is to monitor the forest tree

K. P. Chethan; K. G. Aravind; S. Jayaraman; P. Balamuralidhar

2010-01-01

170

No-migration variance petition: Draft. Volume 4, Appendices DIF, GAS, GCR (Volume 1)  

SciTech Connect

The Department of Energy is responsible for the disposition of transuranic (TRU) waste generated by national defense-related activities. Approximately 2.6 million cubic feet of the se waste have been generated and are stored at various facilities across the country. The Waste Isolation Pilot Plant (WIPP), was sited and constructed to meet stringent disposal requirements. In order to permanently dispose of TRU waste, the DOE has elected to petition the US EPA for a variance from the Land Disposal Restrictions of RCRA. This document fulfills the reporting requirements for the petition. This report is volume 4 of the petition which presents details about the transport characteristics across drum filter vents and polymer bags; gas generation reactions and rates during long-term WIPP operation; and geological characterization of the WIPP site.

NONE

1995-05-31

171

Draft no-migration variance petition. Volume 5, Appendices: GCR (Vol. 2), HSC, PAR  

SciTech Connect

The Department of Energy is responsible for the disposition of transuranic (TRU) waste generated by national defense-related activities. Approximately 2,6 million cubic feet of these waste have been generated and are stored at various facilities across the country. The Waste Isolation Pilot Plant (WIPP), was sited and constructed to meet stringent disposal requirements. In order to permanently dispose of TRU waste, the DOE has elected to petition the US EPA for a variance from the Land Disposal Restrictions of RCRA. This document fulfills the reporting requirements for the petition. This is Volume 5 of the petition which present details about the geological characterization report, average VOC concentration calculations, and the permeability and porosity of the salado formation.

NONE

1995-05-31

172

ENVIRONMENTAL INFLUENCES ON FUEL BURNUP IN MK. III GCR'S: PART I. EQUILIBRIUM SITUATION (CONTINUED). PART II. EFFECTS OF CONTROL RODS  

Microsoft Academic Search

This note studies the properties of fuel in two particular reactor situations. The first part (a continuation of a previous note) simulates an area of an equilibrium HTR core by a non-leaking supercell. Comparisons are made between these results and the zero-leakage edit of the corresponding WIMS output.Environmental effects, in the form of 9-group bucklings as a function of irradiation,

Ainger

1970-01-01

173

GCR Dose Rate Observed in Lunar Orbit During the Transition from Solar Cycle 23 to Cycle 24  

Microsoft Academic Search

The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument aboard the Lunar Reconnaissance Orbiter (LRO) spacecraft has been measuring the charged particle radiation environment in low-lunar orbit since 2009-06-27. CRaTER's charged particle measurements are made with six fully-depleted Si solid state detectors organized into three coaxially aligned pairs consisting of a ``thin'' (~150 mum) and ``thick'' (~1000 mum)

M. J. Golightly; N. A. Schwadron; H. E. Spence; J. K. Wilson; A. Case; L. Townsend; J. C. Kasper; J. Blake; M. D. Looper; J. Mazur

2010-01-01

174

2D Stochastic Monte Carlo to evaluate the modulation of GCR for inner and outer solar system planets  

Microsoft Academic Search

We developed a 2D Stochastic Monte Carlo model for Cosmic Rays propagation in the Heliosphere. The model solves numerically the transport equation of particles in the heliosphere, including major processes affecting the heliospheric particle transport: diffusion, convection, adiabatic energy losses and drift of particles. We evaluated the modulated flux at several distances from the Sun (i.e. at planetary distances) and

P. Bobik; M. J. Boschini; M. Gervasi; D. Grandi; P. G. Rancoita

2008-01-01

175

Investigation of the Earth Ionosphere during extreme solar events based on two different observation methods  

NASA Astrophysics Data System (ADS)

The first approach is based on observations from ground stations to GNSS. Apart from global TEC maps also regional maps were determined and compared to those offered by different analysis centres within the IGS. Beside a solution based on smoothed code also one with double differenced carrier phase were calculated. The research covered not only the present quiet conditions but also periods of extreme solar events like the Halloween events in 2003. The other approach used accelerometer data from LEO like CHAMP and GRACE to calculate the thermospheric density in about 400km height. Results were compared with state of the art models like the Jacchia Bowman 2008.

Krauss, S.; Stangl, G.; Hausleitner, W.

2009-04-01

176

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

177

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

Microsoft Academic Search

Many contemporary sediment-budget studies lack two things: a first-hand understanding of the behavior of the system, and high-frequency data during storm events. In a study designed to understand sediment source areas, we have approach these deficiencies through manual sampling, almost exclusively during storm events. Manual sampling leads to better understanding. Frequently, the researcher finds oneself standing in streams observing phenomenon

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

2001-01-01

178

Event-based stormwater quality and quantity loadings from elevated urban infrastructure affected by transportation.  

PubMed

Urban-rainfall runoff affected by transportation is a complex matrix of a very wide gradation of particulate matter (< 1 to > 10 000 microm) and dissolved inorganic and organic constituents. Particulate matter transported by rainfall runoff can be a significant vector for many reactive particulate-bound constituents, particularly metal elements. The water quality and hydrology of nine events from a representative elevated section of Interstate 10 (I-10) (eastbound average daily traffic load of 70 400 vehicles) in Baton Rouge, Louisiana, were characterized and compared with respect to the passage of each hydrograph. Residence time on the paved concrete surface was less than 30 minutes for all events. Results indicate that event-mean concentrations (EMCs) of particulate matter as total-suspended solids (TSS) (138 to 561 mg/L) and chemical-oxygen demand (COD) (128 to 1440 mg/L) were greater than those found in untreated municipal wastewater from the same service area. Particulate-matter dissolution and COD partitioned as a function of pH, pavement residence time, and organic content. In general, delivery of mass for aggregate indices, such as particulate matter (measured as TSS) and COD mass, were driven by the hydrology of the event, while concentrations of aggregate-constituent measurements, such as total-dissolved solids (TDS), illustrated an exponential-type decline during the rising limb of the hydrograph. Despite the short residence times, wide solids gradation, partitioning, and complexity of the rainfall-runoff chemistry, conductivity and dissolved solids were strongly correlated. Characterization of the transport and loads of constituents in urban-rainfall runoff, as a function of hydrology, is a necessary first step when considering treatability, structural or nonstructural controls, and mass trading for discharges from paved infrastructure. PMID:16121503

Sansalone, John J; Hird, Jonathan P; Cartledge, Frank K; Tittlebaum, Marty E

179

Hybrid system for event-based planning and control of robot operation  

Microsoft Academic Search

The hybrid systems contain two distinct types of components, subsystem with continuous dynamics and subsystem with discrete dynamics that interact with each other. Such hybrid systems arise in varied contexts in manufacturing, communication networks, auto-pilot design, and traffic control and in robotics and mechatronics, among others. Hybrid systems have a central role in embedded control systems that interact with the

Karel Jezernik; A. Hace

2010-01-01

180

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

Microsoft Academic Search

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

José Antonio Pérez-Carrasco; Begoña Acha; Carmen Serrano; Luis A. Camuñas-Mesa; Teresa Serrano-Gotarredona; Bernabé Linares-Barranco

2010-01-01

181

A bio-inspired event-based size and position invariant human posture recognition algorithm  

Microsoft Academic Search

This paper proposes a new approach to recognize human postures in realtime video sequences. The algorithm employs temporal difference imaging between video sequences as input and then decompose the contour of the active object into vectorial line segments. A scheme based on simplified line segment Hausdorff distance combined with projection histograms is proposed to achieve size and position invariance recognition.

Shoushun Chen; Berin Martini; Eugenio Culurciello

2009-01-01

182

Reliable Routing of Event Notifications over P2P Overlay Routing Substrate in Event Based Middleware  

Microsoft Academic Search

Event broker networks(EBN) are a scalable incarna- tion of the publish subscribe paradigm for building asyn- chronous systems. These take the form of overlays of broker nodes and several routing schemes exist that deliver events from publishers to subscribers efficiently on different over- lay structures. However qualities of service based routing schemes are rare and our work addresses this gap.

Shruti P. Mahambre; Umesh Bellur

2007-01-01

183

Event based statistics from high spatial and temporal resolution gauge and radar data  

NASA Astrophysics Data System (ADS)

Studies of extreme precipitation is often focused on daily resolution and for point measurements, i.e. gauge data. A main problem with this coarse temporal resolution is the strong averaging effect on short events. Here we present a study based on high temporal resolution (five minutes) data from radar (1x1 km horizontal resolution) and a high spatial density gauge data set over southwestern Germany. For the gauge data, an event is defined as a sequence of consecutive precipitation measurements above the measurement threshold, while for radar data the events are defined as continuous horizontal regions with above measurement limit intensities. With samples from about two years of data for the radar and from about 90 gauges each with 8 years of data, we get solid statistics for different aspects of the event distributions. A strong relationship between the temporal and spatial definitions of events is found. Additional use of synoptic observations allow the distinction of convective and stratiform precipitation types. The two types show largely different intensity distributions and characteristics for both spatial and temporal statistics. With probability and intensity distributions of the events, it is possible to calculate statistics of the precipitation yield from different duration (or size) events. We found that the yield from stratiform events decrease in a near power-law manner, while convective precipitation shows a concave dependence an a log-log scale, with the largest yields for events of around 20 minutes duration or 30 km2 area. The results emphasise the utility of high temporal resolution data of less than one hour, which allows proper resolution of convective showers and additionally to derive event statistics, which are important for impact assessments.

Berg, Peter; Eggert, Bastian; Haerter, Jan; Moseley, Christopher

2013-04-01

184

Environmental response to volcanic events based on annually laminated sediments from Lake Van, Turkey  

NASA Astrophysics Data System (ADS)

High resolution palynology of lake sediments provides not only a tool to detect short-term climate fluctuations or anthropogenic impacts, but also to study rapid environmental change through catastrophic events. Numerous studies have dealt with vegetation disturbance from recent volcanic events; however, only few prehistoric volcanic events and their impact on the surrounding vegetation have been the focus of palynological investigations. Here we present new results of high resolution pollen studies from Lake Van, one of the largest alkaline lakes in the world. The lake is situated on the plateau of Eastern Anatolia (Turkey), an area of high tectonic activity. Lake Van itself is surrounded by at least three volcanic centres that have been active until the 19th century. Eastern Anatolia has a semiarid continental climate and a vegetation dominated by oak-steppe forest. Cores taken during a research campaign in 2004 consist of annually laminated sediments covering the Holocene and Weichselian Late Glacial. The cores contain 16 tephra layers that document the volcanic history of the area. High resolution (< 5 years/sample) palynological investigations indicate large-scale vegetation disturbances caused by a Late Holocene volcanic eruption and also illustrate the process of recovery of the forest steppe vegetation. Statistical analysis of the pollen data show clear correlations between tephra thickness, tephra provenance, and vegetation disturbance. Although the Lake Van basin has a long history of human inhabitation, particularly in the Middle Iron Age when it was centre of the Urartian Kingdom, in view of our preliminary results, a volcanic impact on human activities in the Lake Van area has not been detected.

Riedel, Nils; Litt, Thomas

2010-05-01

185

Suspended solids transport: an analysis based on turbidity measurements and event based fully calibrated hydrodynamic models.  

PubMed

Modelling suspended solids transport is a key issue for predicting the pollution load discharged by CSOs. Nonetheless, there is still much debate on the main drivers for suspended solids transport and on the modelling approach to be adopted. Current sewer models provide suspended solids transport models. These models, however, rely upon erosion-deposition criteria developed in fluvial environments, therewith oversimplifying the sewer sediment characteristics. Consequently, the performance of these models is poor from a theoretical point of view. To get an improved understanding of the temporal and spatial variations in suspended solids transport, a measuring network was installed in the sewer system of Loenen in conjunction with a hydraulic measuring network from June through December 2001. During the measuring period, 15 storm events rendered high-quality data on both the hydraulics and the turbidity. For each storm event, a hydrodynamic model was calibrated using the Clemens' method. The conclusion of the paper is that modelling of suspended solids transport has been and will be one of the challenges in the field of urban drainage modelling. A direct relation of either shear stress or flow velocity with turbidity could not be found, likely because of the time varying characteristics of the suspended solids. PMID:16206848

Langeveld, J G; Veldkamp, R G; Clemens, F

2005-01-01

186

The succession of Hirnantian events based on data from Baltica: brachiopods, chitinozoans, conodonts, and carbon isotopes  

Microsoft Academic Search

The Hirnantian (late Ordovician) environment was complex and dynamic. Understanding the correct order of events and their precise correlation with a time scale are extremely important for the development of different kinds of environmental interpretations. The lower boundary of the Hirnantian Stage is officially defined by \\

Dimitri Kaljo; Linda Hints; Peep Männik; Jaak Nõlvak

2008-01-01

187

Event-based Production Rules for Data Aggregation in Wireless Sensor Networks  

Microsoft Academic Search

Traditional sensor networks assume that the sensors are pre-programmed and send their data to a central station where the data is aggregated and analysed. However, energy is a major bottleneck resource in wireless sensor networks, e.g. the lifespan of a node is often determined by its battery lifespan. Since each transmitted bit consumes network power it is necessary to reduce

Michael Wenz; Heinz Worn

2006-01-01

188

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

2013-07-22

189

Event-based experiments in an assistive environment using wireless sensor networks and voice recognition  

Microsoft Academic Search

As the population is aging, more and more people require additional health care, either at home, in the work place or in a nursing facility. Now, a need exists for health monitoring outside of hospital conditions. These new conditions make this technology of interest for developing health care monitoring systems that can be deployed in many different environments, including the

Eric Becker; Zhengyi Le; Yong Lin; Fillia Makedon

2009-01-01

190

Event-Based Pixel Sensitive to Changes of Color and Brightness  

Microsoft Academic Search

Vision sensors whose pixels asynchronously generate informative output events are gathering increasing interest be- cause they can reduce the data latency, rate, and redundancy, while also increasing dynamic range. This paper proposes such a dynamic vision sensor (DVS) pixel which is aimed at color vision (cDVS). The pixel combines subthreshold continuous time analog circuits with event-driven switched capacitor amplifiers and

Raphael Berner; Tobi Delbruck

2011-01-01

191

Fast sensory motor control based on event-based hybrid neuromorphic-procedural system  

Microsoft Academic Search

Abstract—Fast sensory-motor processing is challenging when using traditional frame-based cameras and computers. Here we show how a hybrid neuromorphic-procedural system consisting of an address-event silicon retina, a computer, and a servo motor can be used to implement a fast sensory-motor reactive controller totrack and block balls shot at a goal. The system consists of a 128x128 retina that asynchronously reports

Tobi Delbrück; Patrick Lichtsteiner

2007-01-01

192

Association rules analysis of human factor events based on statistics method in digital nuclear power plant  

Microsoft Academic Search

With human factor events rising in recent years, many researches begin to pay much attention to them. Especially, human factor events in nuclear power plant show more important than other human factor events. To effectively decrease human factor events, the authors propose the method of association rule analysis of human factor events in this paper. Association rule is one of

Jian-jun Jiang; Li Zhang; Yi-qun Wang; Kun Zhang; Da-Xin Yang; Wen He

2011-01-01

193

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

Microsoft Academic Search

This research evaluated the POWERFUL IDEAS IN PHYSICAL SCIENCE (PIiPS) curriculum model used to develop a physical science course taken by preservice elementary teachers. The focus was on the evaluation of discrepant events used to induce conceptual change in relation to students' ideas concerning heat, temperature, and specific heat. Both quantitative and qualitative methodologies were used for the analysis. Data

James Edward Lilly

1999-01-01

194

Event-Based Plausibility Immediately Influences On-Line Language Comprehension  

ERIC Educational Resources Information Center

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

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

2011-01-01

195

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

Microsoft Academic Search

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

ISABEL SANMARTÍN; FREDRIK RONQUIST

2004-01-01

196

Identify Alternative Splicing Events Based on Position-Specific Evolutionary Conservation  

Microsoft Academic Search

Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints

Liang Chen; Sika Zheng; Jason E. Stajich

2008-01-01

197

From state-based to event-based contextual security policies  

Microsoft Academic Search

In this paper, we present a formal contextual security model for pervasive computing applications. Main features of the model are: support of authorization and obligation policies, monitoring and dynamic revocation of access rights, support of personalized security rule contexts, and support of collaborative applications. The model is also logic-based. Therefore, it enables the use of formal policy conflict and dynamic

Yehia Elrakaiby; Frédéric Cuppens; Nora Cuppens-boulahia

2009-01-01

198

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

199

Event-Based Method for Detecting Trojan Horses in Mobile Devices  

Microsoft Academic Search

\\u000a Mobile phones and wireless technology and its constant evolution have, in the last years, revolutionized the way in which\\u000a we communicate and work. However, one of the main barriers encounter in the use of these technologies is data security. Trojan\\u000a horses are dangerous software to attack phones, PDAs and Smartphones. New versions are created everyday to attack the functionality,\\u000a theft

Daniel Fuentes; Juan Antonio Álvarez; Juan Antonio Ortega; Francisco Velasco

2010-01-01

200

Exploiting an Event-Based Communication Infrastructure for Rule Based Alerting in Sensor Webs  

Microsoft Academic Search

Sensor Webs deployed to collect and disseminate real\\/near real time data enable ad hoc monitoring of environmental phenomena. This real time data dissemination capability can be exploited to monitor natural and human induced hazards and subsequently broadcast alert notifications to decision makers, emergency managers and general public of an ensuing event. A sensor Web-based architecture for real time alert notifications

Anish Joshi; Andreas Wytzisk

2005-01-01

201

Toward real-time particle tracking using an event-based dynamic vision sensor  

NASA Astrophysics Data System (ADS)

Optically based measurements in high Reynolds number fluid flows often require high-speed imaging techniques. These cameras typically record data internally and thus are limited by the amount of onboard memory available. A novel camera technology for use in particle tracking velocimetry is presented in this paper. This technology consists of a dynamic vision sensor in which pixels operate in parallel, transmitting asynchronous events only when relative changes in intensity of approximately 10% are encountered with a temporal resolution of 1 ?s. This results in a recording system whose data storage and bandwidth requirements are about 100 times smaller than a typical high-speed image sensor. Post-processing times of data collected from this sensor also increase to about 10 times faster than real time. We present a proof-of-concept study comparing this novel sensor with a high-speed CMOS camera capable of recording up to 2,000 fps at 1,024 × 1,024 pixels. Comparisons are made in the ability of each system to track dense (? >1 g/cm3) particles in a solid-liquid two-phase pipe flow. Reynolds numbers based on the bulk velocity and pipe diameter up to 100,000 are investigated.

Drazen, David; Lichtsteiner, Patrick; Häfliger, Philipp; Delbrück, Tobi; Jensen, Atle

2011-11-01

202

Event-based progression detection strategies using scanning laser polarimetry images of the human retina.  

PubMed

Monitoring glaucoma patients and ensuring optimal treatment requires accurate and precise detection of progression. Many glaucomatous progression detection strategies may be formulated for Scanning Laser Polarimetry (SLP) data of the local nerve fiber thickness. In this paper, several strategies, all based on repeated GDx VCC SLP measurements, are tested to identify the optimal one for clinical use. The parameters of the methods were adapted to yield a set specificity of 97.5% on real image series. For a fixed sensitivity of 90%, the minimally detectable loss was subsequently determined for both localized and diffuse loss. Due to the large size of the required data set, a previously described simulation method was used for assessing the minimally detectable loss. The optimal strategy was identified and was based on two baseline visits and two follow-up visits, requiring two-out-of-four positive tests. Its associated minimally detectable loss was 5-12 ?m, depending on the reproducibility of the measurements. PMID:21803348

Vermeer, K A; Lo, B; Zhou, Q; Vos, F M; Vossepoel, A M; Lemij, H G

2011-07-30

203

The Constitution is a Living Document: A Current Events-Based Strategy.  

ERIC Educational Resources Information Center

|Provides a list of 23 activities which demonstrate how constitutional issues and law are manifested in current events. Maintains that the activities help students gain a working knowledge of the U.S. Constitution in addition to seeing it as a relevant, living document which inspires critical and creative thinking. (JDH)|

Rinaldo, Angie

1988-01-01

204

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

205

Event-Based Data Distribution Mechanism for Collaborative Mobile Augmented Reality and Virtual Environments.  

National Technical Information Service (NTIS)

The full power of mobile augmented and virtual reality systems is realized when these systems are connected to one another, to immersive virtual environments, and to remote information servers. Connections are usually made through wireless networks. Howev...

D. Brown M. A. Livingston S. Julier Y. Baillot

2003-01-01

206

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

207

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

NASA Astrophysics Data System (ADS)

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

Chua, L. H. C.

2012-04-01

208

Team-Teaching a Current Events-Based Biology Course for Nonmajors  

ERIC Educational Resources Information Center

Rice University has created a team-taught interactive biology course for nonmajors with a focus on cutting edge biology in the news--advances in biotechnology, medicine, and science policy, along with the biological principles and methodology upon which these advances are based. The challenges inherent to teaching current topics were minimized by…

Bondos, Sarah E.; Phillips, Dereth

2008-01-01

209

Belief Functions on MV-Algebras of Fuzzy Events Based on Fuzzy Evidence  

Microsoft Academic Search

\\u000a Recently Kroupa has proposed a generalization of belief functions on MV-algebras, the latter being the chosen algebraic setting\\u000a for fuzzy (or many-valued) events. However, Kroupa’s belief functions evaluate the degree of belief in the occurrence of fuzzy\\u000a events by taking into account (weighted) evidence on classical subsets. In other words, the focal elements, used in determining\\u000a the degree of belief,

T. Flaminio; L. Godo; E. Marchioni

210

US\\/FRG umbrella agreement for cooperation in GCR development. Fuel, fission products, and graphite subprogram. Quarterly status report, January 1, 1982March 31, 1982  

Microsoft Academic Search

Technical highlights of the period were: Mr. David L. Hanson began a one-year assignment from GA to KFA as a technical specialist working in the area of fission product transport validation; benchmark calculations for verification of fission product release codes were exchanged between GA and HRB (PWS FP-2); fuel capsule R2-K13 was shut down during the entire period while the

1982-01-01

211

Transcriptional regulatory analysis reveals PDR3 and GCR1 as regulators of significantly induced genes by 5-hydroxymethylfurfural stress involved in bioethanol conversion for ethanologenic yeast Saccharomyces cerevisiae  

Technology Transfer Automated Retrieval System (TEKTRAN)

5-Hydroxymethylfurfural (HMF) is one of major inhibitory compounds derived from dehydration of hexoses during biomass degradation using dilute acid hydrolysis. It inhibits yeast growth, reduces enzymatic activities, breaks down DNA, and represses protein and RNA synthesis. We study stress toleranc...

212

AdScorer: an event-based system for near real-time impact analysis of television advertisements (industry article)  

Microsoft Academic Search

The media measurement industry is in turmoil, with the old prediction-based models being challenged by more accurate measurement techniques, based on actual viewer behaviour drawn from much larger sample selections. As measurement methods converge across different types of media, the online\\/offline measurement divide will diminish. Television is one such medium that has traditionally required offline measurements. Advertisers are, for the

Pål Evensen; Hein Meling

2012-01-01

213

Violence Among Men and Women in Substance Use Disorder Treatment: A Multi-level Event-based Analysis  

PubMed Central

Background This study examined associations between acute alcohol and drug use and violence towards others in conflict incidents (overall, partner, and non-partner conflict incidents) by men and women recruited from substance use disorder (SUD) treatment. Methods Semi-structured interviews were used to obtain details about interpersonal conflict incidents (substance use, whether specific conflicts were with intimate partners or non-partners) in the 180 days pre-treatment. Participants for this study were selected for screening positive for past-year violence (N = 160; 77% men, 23% women). Results Multilevel multinomial regression models showed that after adjusting for clustering within individual participants, the most consistent predictors of violence across models were acute cocaine use (significant for overall, intimate partner and non-partner models), acute heavy alcohol use (significant for overall and non-partner models), and male gender (significant in all models). Conclusions This study was the first to explicitly examine the role of acute alcohol and drug use across overall, partner and non-partner conflict incidents. Consistent with prior studies using a variety of methodologies, alcohol, cocaine use and male gender were most consistently and positively related to violence severity (e.g., resulting in injury). The results provide important and novel event-level information regarding the relationship between acute alcohol and specific drug use and the severity of violence in interpersonal conflict incidents.

Chermack, Stephen T.; Grogan-Kaylor, Andy; Perron, Brian E.; Murray, Regan L.; De Chavez, Peter; Walton, Maureen A.

2010-01-01

214

Discrete-event-based planning and control of telerobotic part-mating process with communication delay and geometric uncertainty  

Microsoft Academic Search

This paper presents a new planning\\/control method to integrate the master and slave site in a teleprogramming system in the framework of a discrete-event dynamic system model. Specifically, a simple telerobotic part-mating task environment is modelled based on a class of controlled Petri net (CPN) by associating contact states between objects with state places, and the model is used as

Young-Jo Cho; Tetsuo Kotoku; Kazuo Tanie

1995-01-01

215

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

216

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

Microsoft Academic Search

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

Abdullah Özer; S. Eren Semercigil

2008-01-01

217

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

PubMed

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. Recently reported analyses of ice core samples indicate that the Carrington flare of 1859 is the largest event observed in the past 500 years. These ice core data yield estimates of the proton fluence for energies greater than 30 MeV, but provide no other spectrum information. Assuming that the proton energy distribution for such an event is similar to that measured for other recent, large events, interplanetary crew doses are estimated for these hypothetical worst case SPE spectra. These estimated doses are life threatening unless substantial shielding is provided. PMID:15835055

Stephens, Daniel L; Townsend, Lawrence W; Hoff, Jennifer L

218

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

Microsoft Academic Search

Prospective memory (PM) is the formation of an intention and remembering to perform this intention at a future time or in response to specific cues. PM tasks are a ubiquitous part of daily life. Currently, there is a paucity of information regarding PM impairments in children with traumatic brain injury (TBI) and less empirical evidence regarding effective remediation strategies to

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

2009-01-01

219

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

220

OGLE2009-BLG-023\\/MOA2009-BLG-028: characterization of a binary microlensing event based on survey data  

Microsoft Academic Search

We report the result of the analysis of the light curve of a caustic-crossing binary-lens microlensing event OGLE-2009-BLG-023\\/MOA-2009-BLG-028. Even though the event was observed solely by survey experiments, we could uniquely determine the mass of the lens and distance to it by simultaneously measuring the Einstein radius and lens parallax. From this, we find that the lens system is composed

K.-H. Hwang; C. Han; A. Udalski; T. Sumi; A. Gould; M. Jaroszynski; M. Kubiak; M. K. Szymanski; G. Pietrzynski; I. Soszynski; O. Szewczyk; K. Ulaczyk; L. Wyrzykowski; F. Abe; D. P. Bennett; I. A. Bond; C. S. Botzler; M. Freeman; A. Fukui; K. Furusawa; J. B. Hearnshaw; Y. Itow; K. Kamiya; P. M. Kilmartin; A. Korpela; W. Lin; C. H. Ling; K. Masuda; Y. Matsubara; N. Miyake; Y. Muraki; K. Ohnishi; Y. C. Perrott; N. J. Rattenbury; To. Saito; T. Sako; D. J. Sullivan; W. L. Sweatman; P. J. Tristram; P. C. M. Yock

2011-01-01

221

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

222

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

223

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

224

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

NASA Astrophysics Data System (ADS)

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. Recently reported analyses of ice core samples indicate that the Carrington flare of 1859 is the largest event observed in the past 500 years. These ice core data yield estimates of the proton fluence for energies greater than 30 MeV, but provide no other spectrum information. Assuming that the proton energy distribution for such an event is similar to that measured for other recent, large events, interplanetary crew doses are estimated for these hypothetical worst case SPE spectra. These estimated doses are life threatening unless substantial shielding is provided.

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

2005-05-01

225

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

226

Analysis of power saving multicasting routing applications for Mica2 motes-an event based MATLAB implementation  

Microsoft Academic Search

The adhoc networks are considered to be infrastructure less networks therefore the scarcity of resources (i.e. Bandwidth and Energy) are the main issues requiring attention. In this paper the routing applications\\/algorithms for optimizing battery life time are analyzed while taking into account the highly unreliable real time behavior of mica2 motes. Routing applications are run in Matlab based probabilistic event

P. K. Gaur; B. S. Dhaliwal; A. Seehra

2009-01-01

227

Empirical Research on Economic Impact of Mega-Event: Based on the Case of 2008 Beijing Olympic Games  

Microsoft Academic Search

Mega-event has received growing attention as it brings great economic benefit to the host country or city. However, Macro-economic approach is the main method used in current researches. Based on 2008 Olympic Games in China, this paper researches on both short-term and long-term Micro-economic impact of Mega-event, using event study method and trend analysis. Employing the financial data of listed

Liu Tingli; Wang Chengqing

2010-01-01

228

An event-based model for disease progression and its application in familial Alzheimer's disease and Huntington's disease.  

PubMed

Understanding the progression of neurological diseases is vital for accurate and early diagnosis and treatment planning. We introduce a new characterization of disease progression, which describes the disease as a series of events, each comprising a significant change in patient state. We provide novel algorithms to learn the event ordering from heterogeneous measurements over a whole patient cohort and demonstrate using combined imaging and clinical data from familial Alzheimer's and Huntington's disease cohorts. Results provide new detail in the progression pattern of these diseases, while confirming known features, and give unique insight into the variability of progression over the cohort. The key advantage of the new model and algorithms over previous progression models is that they do not require a priori division of the patients into clinical stages. The model and its formulation extend naturally to a wide range of other diseases and developmental processes and accommodate cross-sectional and longitudinal input data. PMID:22281676

Fonteijn, Hubert M; Modat, Marc; Clarkson, Matthew J; Barnes, Josephine; Lehmann, Manja; Hobbs, Nicola Z; Scahill, Rachael I; Tabrizi, Sarah J; Ourselin, Sebastien; Fox, Nick C; Alexander, Daniel C

2012-01-16

229

BOOK REVIEW: Fluence-Based and Microdosimetric Event-Based Methods for Radiation Protection in Space (NCRP Report No 137)  

Microsoft Academic Search

National Council on Radiation Protection and Measurements Bethesda, MD: NCRP This is the third report of the National Council on Radiation Protection and Measurements which considers the potential radiation hazards associated with human activities in Space. The previous publications (1989 and 2000) considered these hazards largely in the conventional terms of absorbed dose and quality factors, and were guided by

J. Simmons

2002-01-01

230

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

231

Executive and theory-of-mind contributions to event-based prospective memory in children: exploring the self-projection hypothesis.  

PubMed

In two studies, 4- to 6-year-olds were asked to name pictures of animals for the benefit of a watching hand puppet (the ongoing task) but to refrain from naming and to remove from view any pictures of dogs (the prospective memory [PM] task). Children also completed assessments of verbal ability, cognitive inhibition, working memory, and false-belief understanding (both studies), empathy (Study 1 only), and performance on false-sign tests that matched the false-belief tests in narrative content and structure (Study 2 only). Both studies found that inhibition and false-belief performance made unique contributions to the variance in PM, although in Study 1 the influence of inhibition was evident only when children needed to withhold naming. Study 2 further demonstrated that false-belief performance was the only reliable predictor of whether children remembered to return to the researcher an object that had been loaned to them prior to the picture-naming game. Both experiments uncovered moderate relations between PM and chronological age, but such relations were rarely significant after taking account of cognitive ability. We consider the implications of the findings for (a) current views regarding frontal/executive contributions to PM development and (b) the suggestion that the same brain network underlies various forms of mental self-projection, including envisioning the future and understanding the minds of other people. PMID:22169353

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

2011-12-12

232

Significance of Coronary Calcification for Prediction of Coronary Artery Disease and Cardiac Events Based on 64-Slice Coronary Computed Tomography Angiography  

PubMed Central

This work aims to validate the clinical significance of coronary artery calcium score (CACS) in predicting coronary artery disease (CAD) and cardiac events in 100 symptomatic patients (aged 37–87 years, mean 62.5, 81 males) that were followed up for a mean of 5 years. Our results showed that patients with CAD and cardiac events had significantly higher CACS than those without CAD and cardiac events, respectively. The corresponding data were 1450.42 ± 3471.24 versus 130 ± 188.29 (P < 0.001) for CAD, and 1558.67 ± 513.29 versus 400.46 ± 104.47 (P = 0.031) for cardiac events. Of 72 patients with CAD, cardiac events were found in 56 (77.7%) patients. The prevalence of cardiac events in our cohort was 13.3% for calcium score 0, 50% for score 11–100, 56% for score 101–400, 68.7% for score 401–1,000, and 75.0% for score >1000. Increased CACS (>100) was also associated with an increased frequency of multi-vessel disease. Nonetheless, 3 (20%) out of 15 patients with zero CACS had single-vessel disease. Significant correlation (P < 0.001) was observed between CACS and CAD on a vessel-based analysis for coronary arteries. It is concluded that CACS is significantly correlated with CAD and cardiac events.

Sun, Zhonghua; Tsay, Pei-Kwei; Chan, Tiffany; Hsieh, I-Chang; Chen, Chun-Chi; Wen, Ming-Shien

2013-01-01

233

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

Microsoft Academic Search

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

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

2008-01-01

234

Precipitation induced stream flow: An event based chemical andisotopic study of a small stream in the Great Plains region of theUSA  

SciTech Connect

A small stream in the Great Plains of USA was sampled tounderstand the streamflow components following intense precipitation andthe influence of water storage structures in the drainage basin.Precipitation, stream, ponds, ground-water and soil moisture were sampledfor determination of isotopic (D, 18O) and chemical (Cl, SO4) compositionbefore and after two intense rain events. Following the first stormevent, flow at the downstream locations was generated primarily throughshallow subsurface flow and runoff whereas in the headwaters region --where a pond is located in the stream channel -- shallow ground-water andpond outflow contributed to the flow. The distinct isotopic signatures ofprecipitation and the evaporated pond water allowed separation of theevent water from the other sources that contributed to the flow.Similarly, variations in the Cl and SO4 concentrations helped identifythe relative contributions of ground-water and soil moisture to thestream flow. The relationship between deuterium excess and Cl or SO4content reveals that the early contributions from a rain event tostreamflow depend upon the antecedent climatic conditions and theposition along the stream channel within the watershed. The design ofthis study, in which data from several locations within a watershed werecollected, shows that in small streams changes in relative contributionsfrom ground water and soil moisture complicate hydrograph separation,with surface-water bodies providing additional complexity. It alsodemonstrates the usefulness of combined chemical and isotopic methods inhydrologic investigations, especially the utility of the deuterium excessparameter in quantifying the relative contributions of various sourcecomponents to the stream flow.

Machavaram, Madhav V.; Whittemore, Donald O.; Conrad, Mark E.; Miller, Norman L.

2005-03-22

235

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

ERIC Educational Resources Information Center

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

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

2012-01-01

236

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

237

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

ERIC Educational Resources Information Center

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

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

2012-01-01

238

Upper-ocean thermal structure and heat content off the US West Coast during the 1997 1998 El Niño event based on AXBT and satellite altimetry data  

NASA Astrophysics Data System (ADS)

During the 1997/1998 El Niño event, extensive oceanic temperature profiles were taken off the coast of California in January and February 1998 using Airborne Expendable Bathythermographs (AXBTs). These AXBT measurements are compared with altimetry-based upper-ocean temperature estimates using TOPEX and ERS satellite altimetry data. The altimetry-based temperature estimates are well correlated with the AXBT data, in particular when combining the two satellite data sets together to form a blended altimeter temperature estimate. Both the AXBT and altimetry data show that the nearshore coastal El Niño signal differed from that further offshore. The AXBT data show that near shore, the warm anomalies extended to much greater depths and had greater amplitude. A time series of the satellite-derived layer-averaged temperatures, averaged separately over the nearshore and offshore halves of the AXBT analysis domain, also shows a larger El Niño signal in the nearshore half. The role of local atmospheric forcing of the coastal oceanic temperature anomalies is analyzed using NCEP reanalysis and coastal upwelling data sets. The forcing terms include Ekman pumping, radiation, surface heat fluxes, precipitation, and alongshore wind stresses that drive coastal upwelling (expressed as a coastal downwelling index, CDI). The temperature forcing from all of the terms except the CDI anomalies are small. The CDI anomalies can explain most of the slowly varying temperature changes that occur near the coast during a two-year period spanning the El Niño event, as well as some of the larger amplitude, rapid (monthly) warming episodes that appear to be part of the El Niño signal. Several distinct rapid warming episodes, however, are not correlated with the CDI anomalies, and therefore we conclude that the nearshore El Niño signal originates from a combination of both a remote oceanic pathway and local atmospheric forcing.

Wilczak, James M.; Leben, Robert R.; McCollum, David S.

2007-07-01

239

Simple Scoring Scheme for Calculating the Risk of Acute Coronary Events Based on the 10Year Follow-Up of the Prospective Cardiovascular Münster (PROCAM) Study  

Microsoft Academic Search

Background—The absolute risk of an acute coronary event depends on the totality of risk factors exhibited by an individual, the so-called global risk profile. Although several scoring schemes have been suggested to calculate this profile, many omit information on important variables such as family history of coronary heart disease or LDL cholesterol. Methods and Results—Based on 325 acute coronary events

Gerd Assmann; Paul Cullen; Helmut Schulte

240

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

NASA Astrophysics Data System (ADS)

In order to reproduce slow earthquakes with short duration such as very low frequency events (VLFs) migrating along the trench direction as swarms, we apply a 3-D subduction plate boundary model based on the slowness law of rate- and state-dependent friction, introducing close-set numerous small asperities (rate-weakening regions) at a depth of 30 km under high pore pressure condition, in addition to a large asperity. Our simulation indicates that swarms of slip events occur repeatedly at the small asperities, and these events are similar to the observed slow earthquake group, especially to VLF, on the basis of the relation between characteristic duration and seismic moment. No slip events occur there without the small asperities, which mean that the close-set numerous small asperities may be one of the necessary conditions for generating the short-duration slow earthquakes such as VLFs. In the preseismic stage of the megathrust earthquakes that occur at the large asperity, the swarms of VLFs have higher migration speeds and higher moment release rate as well as shorter recurrence interval. Thus, monitoring the migration of slow earthquakes may be useful in imaging the preseismic slip of megathrust earthquakes.

Ariyoshi, K.; Matsuzawa, T.; Ampuero, J.-P.; Nakata, R.; Hori, T.; Kaneda, Y.; Hino, R.; Hasegawa, A.

2012-08-01

241

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

242

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

243

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

Microsoft Academic Search

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

W. R. Webber

1990-01-01

244

DnaA couples DNA replication and the expression of two cell cycle master regulators  

PubMed Central

Cell cycle progression in Caulobacter is driven by the master transcriptional regulators CtrA and GcrA. The cellular levels of CtrA and GcrA are temporally and spatially out-of-phase during the cell cycle, with CtrA repressing gcrA transcription and GcrA activating ctrA transcription. Here, we show that DnaA, a protein required for the initiation of DNA replication, also functions as a transcriptional activator of gcrA, which in turn activates multiple genes, notably those involved in chromosome replication and segregation. The cellular concentration of DnaA is cell cycle-controlled, peaking at the time of replication initiation and gcrA induction. Regulated proteolysis of GcrA contributes to the cell cycle variations in GcrA abundance. We propose that DnaA couples DNA replication initiation with the expression of the two oscillating regulators GcrA and CtrA and that the DnaA/GcrA/CtrA regulatory cascade drives the forward progression of the Caulobacter cell cycle.

Collier, Justine; Murray, Sean Richard; Shapiro, Lucy

2006-01-01

245

A Physical Model of Cosmogenic Nuclide Production in Stony and Iron Meteoroids on the Basis of Simulation Experiments  

Microsoft Academic Search

By extending and improving earlier model calculations [1-4] of cosmogenic nuclide production by GCR particles in extraterrestrial matter, we can now present a physical model without free parameters for a consistent description of GCR production rates in stony and iron meteoroids. The model takes explicitely into account p and n-induced reactions. GCR 4He particles are considered only approximately. It is

I. Leya; H.-J. Lange; R. Michel; B. Meltzow; U. Herpers; H. Busemann; R. Wieler; B. Dittrich-Hannen; M. Suter; P. W. Kubik

1995-01-01

246

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

Microsoft Academic Search

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

Soma Banerjee; Nilabja Sikdar; Kyungjae Myung

2007-01-01

247

Issues in deep space radiation protection  

Microsoft Academic Search

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

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

2001-01-01

248

Shielding materials for highly penetrating space radiations  

Microsoft Academic Search

Interplanetary travel involves the transfer from an Earth orbit to a solar orbit. Once outside the Earth's magnetosphere, the major sources of particulate radiation are solar cosmic rays (SCR's) and galactic cosmic rays (GCR's). Intense fluxes of SCR's come from solar flares and consist primarily of protons with energies up to 1 GeV. The GCR consists of a low flux

Richard L. Kiefer; Robert A. Orwoll

1995-01-01

249

Martian Radiation Environment Experiment (MARIE)  

Microsoft Academic Search

Space radiation presents a very serious hazard to crews of interplanetary human missions. The two sources of this radiation are the galactic cosmic rays (GCR) and solar energetic particle (SEP) events. The GCR provides a steady source of low dose rate radiation that is primarily responsible for stochastic effects, such as cancer, and can effect the response of the central

Gautam D. Badhwar

1999-01-01

250

Mars Surface Ionizing Radiation Environment: Need for Validation  

Microsoft Academic Search

Protection against the hazards from exposure to ionizing radiation remains an unresolved issue in the Human Exploration and Development of Space (HEDS) enterprise [1]. The major uncertainty is the lack of data on biological response to galactic cosmic ray (GCR) exposures but even a full understanding of the physical interaction of GCR with shielding and body tissues is not yet

J. W. Wilson; M. Y. Kim; M. S. Clowdsley; J. H. Heinbockel; R. K. Tripathi; R. C. Singleterry; J. L. Shinn; R. Suggs

1999-01-01

251

The isotopic composition of the elements carbon, oxygen, neon, magnesium, and silicon in the galactic cosmic rays  

Microsoft Academic Search

High resolution observations of the isotopic composition of C, O, Ne, Mg, and Si in the galactic cosmic rays (GCR) are used to derive the isotopic compositions of these elements in the GCR source. It is found that the source is enhanced in the neutron-rich isotopes of Ne, Mg, and Si (relative to solar system composition). The significance and possible

M. E. Wiedenbeck; D. E. Greiner

1981-01-01

252

Gaseous core reactor concept for both low- and burst-power applications  

Microsoft Academic Search

Extensive theoretical and experimental investigations at the Innovative Nuclear Space Power Institute (INSPI) at the University of Florida have shown that gaseous\\/vapor core reactors (GCR) have promising features for space electric power and propulsion applications. The GCR concept presented in this summary consists of two reactor systems: a large central high (burst)-power gaseous core reactor (BPGCR) chamber surrounded by an

M. M. Panicker; E. T. Dugan

1990-01-01

253

Association of Basal Hyperglucagonemia with Impaired Glucagon Counterregulation in Type 1 Diabetes  

PubMed Central

Glucagon counterregulation (GCR) protects against hypoglycemia, but is impaired in type 1 diabetes (T1DM). A model-based analysis of in vivo animal data predicts that the GCR defects are linked to basal hyperglucagonemia. To test this hypothesis we studied the relationship between basal glucagon (BasG) and the GCR response to hypoglycemia in 29 hyperinsulinemic clamps in T1DM patients. Glucose levels were stabilized in euglycemia and then steadily lowered to 50?mg/dL. Glucagon was measured before induction of hypoglycemia and at 10?min intervals after glucose reached levels below 70?mg/dL. GCR was assessed by CumG, the cumulative glucagon levels above basal; MaxG, the maximum glucagon response; and RIG, the relative increase in glucagon over basal. Analysis of the results was performed with our mathematical model of GCR. The model describes interactions between islet peptides and glucose, reproduces the normal GCR axis and its impairment in diabetes. It was used to identify a control mechanism consistent with the observed link between BasG and GCR. Analysis of the clinical data showed that higher BasG was associated with lower GCR response. In particular, CumG and RIG correlated negatively with BasG (r?=??0.46, p?=?0.012 and r?=??0.74, p?GCR in which the secretion of glucagon has two components. The first is under (auto) feedback control and drives a pulsatile GCR and the second is feedback independent (basal secretion) and its increase suppresses the GCR. Our simulations showed that this model explains the observed relationships between BasG and GCR during a three-fold simulated increase in BasG. Our findings support the hypothesis that basal hyperglucagonemia contributes to the GCR impairment in T1DM and show that the predictive power of our GCR animal model applies to human pathophysiology in T1DM.

Farhy, Leon S.; Chan, Alice; Breton, Marc D.; Anderson, Stacey M.; Kovatchev, Boris P.; McCall, Anthony L.

2012-01-01

254

Cosmic rays and climate change over the past 1000 million years  

NASA Astrophysics Data System (ADS)

The Galactic cosmic ray (GCR) intensity has been postulated by others to vary cyclically with a peak to valley ratio of ˜3:1, as the Solar System moves from the Spiral Arm to the Inter-Arm regions of the Galaxy. These intensities have been correlated with global temperatures and used to support the hypothesis of GCR induced climate change. In this paper we show that the model used to deduce such a large ratio of Arm to Interarm GCR intensity requires unlikely values of some of the GCR parameters, particularly the diffusion length in the interstellar medium, if as seems likely to be the case, the diffusion is homogeneous. Comparison is made with the existing gamma ray astronomy data and this also indicates that the ratio is not large. The variation in the intensity is probably of order 10-20% and should be no more than 30% as the Solar System moves between these two regions, unless the conventional parameters of the GCR are incorrect. In addition we show that the variation of the GCR intensity, as the trajectory of the Solar System oscillates about the Galactic Plane, is too small to account for the extinctions of species as has been postulated unless, again, conventional assumptions about the GCR parameters are not correct.

Sloan, T.; Wolfendale, A. W.

2013-12-01

255

Are there persistent physical atmospheric responses to galactic cosmic rays?  

NASA Astrophysics Data System (ADS)

Variations in the annual mean of the galactic cosmic ray flux (GCR) are compared with annual variations in the most common meteorological variables: temperature, mean sea-level barometric pressure, and precipitation statistics. A multiple regression analysis was used to explore the potential for a GCR response on timescales longer than a year and to identify ‘fingerprint’ patterns in time and space associated with GCR as well as greenhouse gas (GHG) concentrations and the El Niño-Southern Oscillation (ENSO). The response pattern associated with GCR consisted of a negative temperature anomaly that was limited to parts of eastern Europe, and a weak anomaly in the sea-level pressure (SLP), but coincided with higher pressure over the Norwegian Sea. It had a similarity to the North Atlantic Oscillation (NAO) in the northern hemisphere and a wave train in the southern hemisphere. A set of Monte Carlo simulations nevertheless indicated that the weak amplitude of the global mean temperature response associated with GCR could easily be due to chance (p-value = 0.6), and there has been no trend in the GCR. Hence, there is little empirical evidence that links GCR to the recent global warming.

Benestad, Rasmus E.

2013-09-01

256

On the depth-dependent production of radionuclides (44?A?59) by solar protons in extraterrestrial matter  

Microsoft Academic Search

In order to interpret cosmogenic radionuclides in extraterrestrial matter one has to differentiate between p- and ?-induced\\u000a reactions with solar (SCR) and with galactic (GCR) cosmic rays. Our earlier studies have shown that for a satisfactory description\\u000a of GCR-interactions with dense matter rather few but characteristic high energy cross sections are required. In contrast,\\u000a for the low and medium energy

R. Michel; G. Brinkmann

1980-01-01

257

Enhanced SCR Proton Flux from the Early Sun, Revisited  

Microsoft Academic Search

Greater concentrations of [21Ne]c in the dark phase of Kapoeta, compared to the light phase, may represent a large irradiation by solar protons (SCR) in the early solar system [1] or a longer galactic cosmic ray (GCR) irradiation [2]. Lunar rock studies demonstrate that the 21Ne\\/22Ne ratio can be used to distinguish between components produced by energetic SCR and GCR

M. N. Rao; D. H. Garrison; D. D. Bogard; R. L. Palma; G. Dreibus

1995-01-01

258

The Structure of the Solar Cycle Maximum Phase in the Galactic Cosmic Ray 11-year Variation  

Microsoft Academic Search

The maximum phase in the solar cycle variation of the galactic cosmic ray (GCR) intensity, J(t), is considered using neutron monitor, balloon and spacecraft data for the last five solar cycles (Nos. 19-23). For all time series considered the double peak structure (DPS) with the gap between the peaks is observed in the GCR modulation, M(t)=[J(t0)-J(t)]\\/J(t0), which proves that M

M. B. Krainev; G. A. Bazilevskaya

2004-01-01

259

A temporal forecast of radiation environments for future space exploration missions  

Microsoft Academic Search

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

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

2007-01-01

260

27-day variations of the galactic cosmic ray intensity and anisotropy in the minimum of the 23rd solar activity cycle  

NASA Astrophysics Data System (ADS)

We study the 27-day variations of the solar wind velocity, galactic cosmic ray (GCR) intensity and anisotropy in the last minimum epoch of solar activity (2007-2009, A < 0). The average amplitude of the 27-day variation of the galactic cosmic ray anisotropy (A27A) in the current minimum epoch of solar activity (2007-2009, A < 0) is lesser than in previous positive polarity period as it is expected from the drift theory. So, polarity dependence rule for the 27-day variation of the GCR anisotropy is fully kept. It is a universal principle for the amplitudes of the 27-day variation of the GCR anisotropy. At the same time, the average amplitude of the 27-day variation of the GCR intensity (A27I) remains at the same level as for previous minimum epoch 1995-1997 (A > 0) showing by the same token an violation of its polarity dependence rule established earlier. We assume that this phenomenon could be generally related with the well established 27-day variation of the solar wind velocity being in anti-correlation with the similar changes of the 27-day variation of the GCR intensity. Generally, a character of the heliolongitudinal asymmetry of spatial large-scale structure of the solar wind velocity (SWV) established in the recent minimum epoch, preferentially pronounces in the behavior of the 27-day variation of the GCR intensity than anisotropy. The formation of the 27-day variation of the GCR anisotropy preferentially takes place in a restricted disk like local vicinity in the helioequatorial region, whilst the 27-day variation of the GCR intensity is formed in the global three dimensional vicinity of the heliosphere.

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

2012-09-01

261

Cosmic rays linked to rapid mid-latitude cloud changes  

NASA Astrophysics Data System (ADS)

The effect of the Galactic Cosmic Ray (GCR) flux on Earth's climate is highly uncertain. Using a novel sampling approach based around observing periods of significant cloud changes, a statistically robust relationship is identified between the rate of GCR flux and the most rapid mid-latitude (60°-30° N/S) cloud decreases operating over daily timescales; this signal is verified in surface level air temperature (SLAT) reanalysis data. A General Circulation Model experiment is used to test the causal relationship of the observed cloud changes to the detected SLAT anomalies. Results indicate that the cloud anomalies were responsible for producing the observed SLAT changes, implying a link between significant decreases in the rate of GCR flux (~0.79%/day (relative to the peak-to-peak amplitude of 11-yr solar cycle)), decreases in cloud cover (~1.9%/day) and increases in SLAT (~0.05 K/day). The influence of GCRs is clearly distinguishable from changes in solar irradiance and the interplanetary magnetic field. These results provide the most compelling evidence presented thus far of a GCR-climate relationship. From this analysis we conclude: (i) a GCR-climate relationship is governed by both the rate of GCR flux and internal precursor conditions; and (ii) it is likely that this natural forcing has not contributed significantly to recent anthropogenic temperature rises.

Laken, B. A.; Kniveton, D. R.; Frogley, M. R.

2010-08-01

262

Cosmogenic-nuclide production by primary cosmic-ray protons  

SciTech Connect

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

Reedy, R.C.

1985-01-01

263

Despiking of energetic proton flux to study galactic cosmic ray modulation  

NASA Astrophysics Data System (ADS)

The solar influence on Galactic cosmic ray (GCR) flux can be generally described as the usually stable "background" modulation. The violent Solar Energetic Particle (SEP) events associated with solar activities can cause surging particle flux. Thus, the GCR flux observation from satellites may be heavily contaminated by spurious spikes due to SEPs. And spike may also arise in the long time series count rates data provided by ground-based neutron monitors, e.g., system glitch. To obtain the "pure" background GCR flux for modulation research, the removal of multifarious spikes is necessary. In this article, we present a robust automatic despiking algorithm based on Poincare map thresholding method to "purify" time-series GCR flux. The algorithm is effective and robust for detecting various types of spikes in the GCR count rates of neutron monitors. In addition, after despiking spacecraft observations of relatively lower energy energetic proton flux using our algorithm, we get both 11-year and 27-day period cycles comparable to the much higher energy GCR count rate data from the ground-based neutron monitors.

Zhao, L.; Qin, G.; Chen, H.

2011-12-01

264

Heliospheric Modulation of Galactic Cosmic Rays Observed at the L1 Lagrange Point in Solar Cycle 23  

NASA Astrophysics Data System (ADS)

We analyze a unique 14-year record of Galactic Cosmic Ray measurements made by the SOHO Coronal Diagnostic Spectrometer NIS detectors, recording integrated GCR numbers with energies above 1.0 GeV between July 1996 and June 2010. The GCR numbers decrease by 50 percent from the 1997 minimum to the 2000 maximum of the solar cycle, then increase back to the 1997 level in 2007 and continue to rise, reaching in December 2009 a level 22% higher than in 1997. This 22% increase is in contrast with the behaviour of Ulysses/KET GCR protons extrapolated to 1 AU in the ecliptic plane, showing the same level in 2008-2010 as in 1997 (Heber et al. 2009). The increase of SOHO/CDS GCR numbers, continuing until 2009, is correlated with the decrease of the tilt angle of the heliospheric current sheet from 30 degrees in mid-2008 to 5 degrees in late 2009. The GCR level then drops sharply from January 2010, again consistent with a rapid increase of the tilt angle to over 35 degrees. We discuss the effect of the structure of the heliospheric current sheet on cosmic ray transport. The CDS/NIS on SOHO currently remains the only space instrument monitoring daily the GCR protons with energies above 1.0 GeV. Unfortunately, CDS operations are to be terminated in 2011.

Fludra, A.

2010-12-01

265

Comparison of collection and land use efficiency for various solar concentrating field geometries  

NASA Astrophysics Data System (ADS)

In this paper we analyze the effects of neighbor shadowing of tracking solar photovoltaic arrays when they are set out in solar farms for large scale generation. Closer tracker spacing yields more power per unit area of land, but less power per tracking unit because of shadowing. A model has been developed to quantify and compare efficiencies for different tracker aspect ratios and field layouts, on an hourly, daily and annual basis. The model accounts for atmospheric absorption as well as neighbor shadowing at low solar altitude angles. We have focused on the case of CPV arrays which are oriented normal to the rays from the sun. The field layout is best characterized by the ratio of total array area to land area (the ground cover ratio or GCR). We explore as a function of GCR both the fraction of all the direct sunlight energy that is intercepted by the arrays (the irradiance collection efficiency) and the energy lost by each array because of shadowing. Examples are worked out for rectangular arrays on dual axis trackers at 33° latitude. We find that for a ground cover ratio of 30% the annual irradiance collection efficiency is 50%, almost independent of the layout pattern or the array aspect ratio. For a ground cover ratio of 40%, the irradiance collection efficiency rises to 65%. The corresponding shadowing losses do depend on aspect ratio, thus for 30% GCR the annual average of shadowing loss is 7.2% for 3:1 aspect ratio, rising to 7.8% for 2:1 aspect ratio. High GCR is not realizable for higher aspect ratios, which lead to large swing radius, but for 2:1 aspect ratio 40% GCR results in shadowing loss of 11.5%. One conclusion is that a solar farm with arrays of 2:1 aspect ratio set out with 40% GCR is good compromise when land is scarce: 64% of all the direct sunlight energy incident on the land is harvested by the arrays, with only 11.5% shadowing loss. We have compared these efficiencies with those for trough CSP systems, which also harvest direct sunlight but with reflectors turning about a single, horizontal N-S axis. For given GCR, the shadowing loss is slightly less (0.5%) than for the above dual-axis arrays, however the irradiance collection efficiency is worse in winter, leading to a lower annual average for a given GCR. For example, at 40% GCR, a single-axis system realizes a 56% irradiance collection efficiency compared to 64% for the dual axis systems.

Stephens, Kyle; Angel, J. Roger P.

266

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

267

Quantitative estimation of dietary energy deficiency and effects of its supplementation on protein nutritional status of nondiabetic uremic patients undergoing protein restricted dietary regimens.  

PubMed

In chronic renal failure (CRF) patients with a reduced protein intake, if the patients' energy intake could be estimated on the basis of biochemical data together with protein intake, it would be easier to provide them with adequate dietary treatment. Thus, from the relationship among the normalized protein catabolic rate (nPCR) and the intrinsic creatinine generation rate (%GCr) both calculated on the basis of 24-hr urine creatinine, as well as the daily dietary energy intake evaluated by a skilled nutritionist, we devised the following equation to estimate the amount of dietary energy deficiency (delta E) whose supplementation increases the %GCr of patients on protein-restricted dietary regimens to the target level (i.e., the dietary energy deficient amount). This was done by taking the %GCr of average nondiabetic hemodialysis patients of the same age and sex as a temporal target level: delta E = [31.22 - 1.97 (%GCr)0.6]/(nPCR)0.15. In order to examine the clinical usefulness of this equation, the daily dietary energy deficient amount calculated by the equation was supplemented with protein-free jelly. As a result, the %GCr increased from approximately three-fourths of the target level to the target level within 4 months. PMID:11486599

Iwayama, N; Shinzato, T; Nakai, S; Ando, S; Nagake, Y; Makino, H; Maeda, K

2001-05-01

268

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

269

Movement patterns of wintering lesser scaup in Grand Calumet River - Indiana Harbor Canal, Indiana  

USGS Publications Warehouse

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 the area. We investigated the feeding and movement patterns of these wintering lesser scaup to better understand the ecological significance of this area to wintering waterfowl and to interpret contaminant levels in these lesser scaup. We implanted radio transmitters in 20 individuals in January 1994 and tracked them until early March 1994. Four lesser scaup disappeared and four died within the first 2 weeks after implantation; 12 lesser scaup remained in the GCR-IHC for the next 6-7 weeks. Individual radio-marked scaup (n = 12) were located in the GCR-IHC on an average of 62.2% (extreme values = 25-87%) of the searches. No radio-marked lesser scaup were located outside the GCR-IHC. Lesser scaup were feeding during 23% of the radio fixes.

Custer, C. M.; Custer, T. W.; Sparks, D. W.; Hines, Randy K.; Kochanny, C. O.

1996-01-01

270

Tumor Necrosis Factor Inhibits Glucocorticoid Receptor Function in Mice  

PubMed Central

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

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

2011-01-01

271

Space radiation protection issues.  

PubMed

The complex charged particle environments in space pose considerable challenges with regard to potential health consequences that can impact mission design and crew selection. The lack of knowledge of the biological effects of different ions in isolation and in combination is a particular concern because the risk uncertainties are very high for both cancer and non-cancer late effects. Reducing the uncertainties is of high priority. Two principal components of space radiation each raise different concerns. Solar particle events (SPE) occur sporadically and are comprised primarily of low- to moderate-energy protons. Galactic cosmic radiation (GCR) is isotropic and relatively invariant in dose rate. GCR is also dominated by protons, but the energy range is wider than in SPE. In addition, the contribution of other light and heavy ions to the health risks from GCR must be addressed. This paper will introduce the principal issues under consideration for space radiation protection. PMID:23032885

Kronenberg, Amy; Cucinotta, Francis A

2012-11-01

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

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

PubMed

Abstract? 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

2013-07-22

274

The role of mediastinal adipose tissue 11?-hydroxysteroid d ehydrogenase type 1 and glucocorticoid expression in the development of coronary atherosclerosis in obese patients with ischemic heart disease  

PubMed Central

Background Visceral fat deposition and its associated atherogenic complications are mediated by glucocorticoids. Cardiac visceral fat comprises mediastinal adipose tissue (MAT) and epicardial adipose tissue (EAT), and MAT is a potential biomarker of risk for obese patients. Aim Our objective was to evaluate the role of EAT and MAT 11beta-hydroxysteroid dehydrogenase type 1 (11?-HSD-1) and glucocorticoid receptor (GCR) expression in comparison with subcutaneous adipose tissue (SAT) in the development of coronary atherosclerosis in obese patients with coronary artery disease (CAD), and to assess their correlations with CD68 and fatty acids from these tissues. Methods and results Expression of 11?-HSD-1 and GCR was measured by qRT-PCR in EAT, MAT and SAT of thirty-one obese patients undergoing coronary artery bypass grafting due to CAD (obese CAD group) and sixteen obese patients without CAD undergoing heart valve surgery (controls). 11?-HSD-1 and GCR expression in MAT were found to be significantly increased in the obese CAD group compared with controls (p?GCR mRNA levels were strongly correlated in MAT. Stearidonic acid was significantly increased in EAT and MAT of the obese CAD group and arachidonic acid was significantly expressed in MAT of the obese male CAD group (p?GCR in MAT compared with EAT and SAT, and also describe the interrelated effects of stearidonic acid, HOMA-IR, plasma cortisol and GCR mRNA levels, explaining 40.2% of the variance in 11?-HSD-1 mRNA levels in MAT of obese CAD patients. These findings support the hypothesis that MAT contributes locally to the development of coronary atherosclerosis via glucocorticoid action.

2012-01-01

275

Cosmic rays linked to rapid mid-latitude cloud changes  

NASA Astrophysics Data System (ADS)

The effect of the Galactic Cosmic Ray (GCR) flux on Earth's climate is highly uncertain. Using a novel sampling approach based around observing periods of significant cloud changes, a statistically robust relationship is identified between short-term GCR flux changes and the most rapid mid-latitude (60°-30° N/S) cloud decreases operating over daily timescales; this signal is verified in surface level air temperature (SLAT) reanalysis data. A General Circulation Model (GCM) experiment is used to test the causal relationship of the observed cloud changes to the detected SLAT anomalies. Results indicate that the anomalous cloud changes were responsible for producing the observed SLAT changes, implying that if there is a causal relationship between significant decreases in the rate of GCR flux (~0.79 GU, where GU denotes a change of 1% of the 11-year solar cycle amplitude in four days) and decreases in cloud cover (~1.9 CU, where CU denotes a change of 1% cloud cover in four days), an increase in SLAT (~0.05 KU, where KU denotes a temperature change of 1 K in four days) can be expected. The influence of GCRs is clearly distinguishable from changes in solar irradiance and the interplanetary magnetic field. However, the results of the GCM experiment are found to be somewhat limited by the ability of the model to successfully reproduce observed cloud cover. These results provide perhaps the most compelling evidence presented thus far of a GCR-climate relationship. From this analysis we conclude that a GCR-climate relationship is governed by both short-term GCR changes and internal atmospheric precursor conditions.

Laken, B. A.; Kniveton, D. R.; Frogley, M. R.

2010-11-01

276

Estimation of Galactic Cosmic Ray exposure inside and outside the Earth's magnetosphere during the recent solar minimum between solar cycles 23 and 24  

NASA Astrophysics Data System (ADS)

The evidently low solar activity observed between solar cycles 23 and 24 during the years 2008-2010 led to a substantial increase in the Galactic Cosmic Ray (GCR) intensity in comparison with preceding solar minima. As the GCRs consist of highly-ionizing charged particles having the potential to cause biological damage, they are a subject of concern for manned missions to space. With the enhanced particle fluxes observed between 2008 and 2010, it is reasonable to assume that the radiation exposure from GCR must have also increased to unusually high levels. In this paper, the GCR exposure outside and inside the Earth's magnetosphere is numerically calculated for time periods starting from 1970 to the end of 2011 in order to investigate the increase in dose levels during the years 2008-2010 in comparison with the last three solar minima. The dose rates were calculated in a water sphere, used as a surrogate for the human body, either unshielded or surrounded by aluminium shielding of 0.3, 10 or 40 g/cm2. By performing such a long-term analysis, it was estimated that the GCR exposure during the recent solar minimum was indeed the largest in comparison with previous minima and that the increase was more pronounced for locations outside the magnetosphere.

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

2013-09-01

277

Rigidity dependence of 11 year cosmic ray modulation: Implication for theories  

Microsoft Academic Search

We use data obtained with the global network of detectors, with median rigidity (Rm) of response covering a wide range (1 to 200 GV), to derive the rigidity dependence of the 11 year modulation of galactic cosmic rays (GCR) for 4 sunspot cycles (20 to 23). We find that observed rigidity dependence is represented by a power law with negative

H. S. Ahluwalia; M. M. Fikani; R. C. Ygbuhay

2010-01-01

278

A heavy ion spectrometer system for the measurement of projectile fragmentation of relativistic heavy ions  

SciTech Connect

The Heavy Ion Spectrometer System (HISS) at the LBL Bevalac provided a unique facility for measuring projectile fragmentation cross sections important in deconvolving the Galactic Cosmic Ray (GCR) source composition. The general characteristics of the apparatus specific to this application are described and the main features of the event reconstruction and analysis used in the TRANSPORT experiment are discussed.

Engelage, J.; Crawford, H.J.; Greiner, L.; Kuo, C. [and others

1996-06-01

279

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

280

Probabilistic assessment of radiation risk for astronauts in space missions  

Microsoft Academic Search

Accurate estimations of the health risks to astronauts due to space radiation exposure are necessary for future lunar and Mars missions. Space radiation consists of solar particle events (SPEs), comprised largely of medium energy protons (less than several hundred MeV); and galactic cosmic rays (GCR), which include high-energy protons and heavy ions. While the frequency distribution of SPEs depends strongly

Myung-Hee Y. Kim; Giovanni De Angelis; Francis A. Cucinotta

2011-01-01

281

Space Radiation Hazards on Human Missions to the Moon and Mars  

Microsoft Academic Search

One of the most significant health risks for humans exploring Earth's moon and Mars is exposure to the harsh space radiation environment. Crews on these exploration missions will be exposed to a complex mixture of very energetic particles. Chronic exposures to the ever-present background galactic cosmic ray (GCR) spectrum consisting of various fluxes of all naturally - occurring chemical elements

L. Townsend

2004-01-01

282

Uncertainties in estimates of the risks of late effects from space radiation  

Microsoft Academic Search

Methods used to project risks in low-Earth orbit are of questionable merit for exploration missions because of the limited radiobiology data and knowledge of galactic cosmic ray (GCR) heavy ions, which causes estimates of the risk of late effects to be highly uncertain. Risk projections involve a product of many biological and physical factors, each of which has a differential

F. A. Cucinotta; W. Schimmerling; J. W. Wilson; L. E. Peterson; P. B. Saganti; J. F. Dicello

2004-01-01

283

An analysis of the SEU rate of microcircuits exposed by the various components of space radiation  

Microsoft Academic Search

In the present paper the experimental and calculated data of SEU rate in microcircuits operating onboard spacecraft are compared. The main features of models and the calculation methods, which are incorporated in the SEREIS software package, are considered. The main features of models, and the calculation methods are considered. The contribution of the different space radiation components (ERB Protons; GCR

V. F. Bashkirov; N. V. Kuznetsov; R. A. Nymmik

1999-01-01

284

Evaluating shielding effectiveness for reducing space radiation cancer risks  

Microsoft Academic Search

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 PDFs are used in significance tests for evaluating 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

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

2006-01-01

285

Lunar soil as shielding against space radiation  

Microsoft Academic Search

We have measured the radiation transport and dose reduction properties of lunar soil with respect to selected heavy ion beams with charges and energies comparable to some components of the galactic cosmic radiation (GCR), using soil samples returned by the Apollo missions and several types of synthetic soil glasses and lunar soil simulants. The suitability for shielding studies of synthetic

J. Miller; L. Taylor; C. Zeitlin; L. Heilbronn; S. Guetersloh; M. DiGiuseppe; Y. Iwata; T. Murakami

2009-01-01

286

A space radiation shielding model of the 2001 Mars Odyssey spacecraft and the martian radiation environment experiment (Marie)  

Microsoft Academic Search

The 2001 Mars Odyssey spacecraft was launched toward Mars on April 7, 2001. Onboard the spacecraft is the Martian Radiation Environment Experiment (MARIE), which is designed to measure galactic cosmic radiation (GCR) and solar particle events in the 20 - 500 MeV\\/u energy range. We describe a space radiation-shielding model of the 2001 Mars Odyssey spacecraft that includes the MARIE

W. Atwell; P. Saganti

2002-01-01

287

Energy dependence of the rigidity spectrum of Forbush decrease of galactic cosmic ray intensity  

Microsoft Academic Search

We show that rigidity spectrum of Forbush decrease (Fd) of galactic cosmic ray (GCR) intensity in September 9–23, 2005 clearly depends on energy. We calculated rigidity spectrum of the Fd based on the neutron monitors and Nagoya muon telescope channels’ data divided in three groups according to their cut off rigidities. We found that temporal changes of rigidity spectrum exponent

Michael V. Alania; Anna Wawrzynczak

288

Propulsion capabilities and limitations of the Gas Core Nuclear Rocket  

Microsoft Academic Search

The Gas Core Nuclear Rocket (GCR) is described in terms of the Space Exploration Initiative and the open-cycle version of this concept. The version is capable of generating several thousand seconds of specific impulse and hundreds of kilonewtons of thrust allowing a round trip to Mars in several months. Some of the physics and engineering issues are described that must

Terry Kammash

1992-01-01

289

Radiation Effects and Protection for Moon and Mars Missions  

Microsoft Academic Search

Manned and robotic missions to the Earth's moon and Mars are exposed to a continuous flux of Galactic Cosmic Rays (GCR) and occasional, but intense, fluxes of Solar Energetic Particles (SEP). These natural radiations impose hazards to manned exploration, but also present some constraints to the design of robotic missions. The hazards to interplanetary flight crews and their uncertainties have

Thomas A. Parnell; Tony W. Armstrong

290

The projection of space radiation environments with a solar cycle statistical model  

NASA Astrophysics Data System (ADS)

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

Kim, M. Y.; Cucinotta, F. A.; Wilson, J. W.

291

Some aspects of galactic cosmic ray acceleration  

NASA Astrophysics Data System (ADS)

I give a synopsis of two aspects of the Galactic Cosmic Ray (GCR) acceleration problem: the importance of the medium energy gamma-ray window, and several specific astrophysical sources which merit further investigation. NOTE: figures may be found in the on-line version only: atro-ph/0309758.

Butt, Yousaf Mahmood

2005-01-01

292

Special applications of gas-cooled reactors  

SciTech Connect

The HTGR technology has been demonstrated by Peach Bottom, Fort St. Vrain, and AVR. Another member of the GCR family is the GCFR. Energy requirements for process heat applications of the HTGR high-temperature nuclear heat source are tabulated. 2 tables. (DLC)

Peinado, C.O.

1981-02-01

293

Special Applications of Gas-Cooled Reactors.  

National Technical Information Service (NTIS)

The HTGR technology has been demonstrated by Peach Bottom, Fort St. Vrain, and AVR. Another member of the GCR family is the GCFR. Energy requirements for process heat applications of the HTGR high-temperature nuclear heat source are tabulated. 2 tables. (...

C. O. Peinado

1981-01-01

294

IAEA activities in Gas-cooled Reactor technology development  

SciTech Connect

The International Atomic Energy Agency (IAEA) has the charter to ``foster the exchange of scientific and technical information``, and ``encourage and assist research on, and development and practical application of, atomic energy for peaceful uses throughout the world``. This paper describes the Agency`s activities in Gas-cooled Reactor (GCR) technology development.

Cleveland, J. [Oak Ridge National Lab., TN (United States); Kupitz, J. [International Atomic Energy Agency, Vienna (Austria)

1992-12-31

295

IAEA activities in Gas-cooled Reactor technology development  

SciTech Connect

The International Atomic Energy Agency (IAEA) has the charter to foster the exchange of scientific and technical information'', and encourage and assist research on, and development and practical application of, atomic energy for peaceful uses throughout the world''. This paper describes the Agency's activities in Gas-cooled Reactor (GCR) technology development.

Cleveland, J. (Oak Ridge National Lab., TN (United States)); Kupitz, J. (International Atomic Energy Agency, Vienna (Austria))

1992-01-01

296

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

297

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

Microsoft Academic Search

The International Space Station (ISS) living areas receive the preponderance of ionizing radiation exposure from Galactic Cosmic Rays (GCR) and geomagnetically trapped protons. Practically all trapped proton exposure occurs when the ISS passes through the South Atlantic Anomaly (SAA) region. The fact that this region is in proximity to a trapping \\

Brooke M. Anderson; John E. Nealy; Nathan J. Luetke; Christopher A. Sandridge; Garry D. Qualls

298

Solar irradiance, cosmic rays and cloudiness over daily timescales  

NASA Astrophysics Data System (ADS)

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

Laken, Benjamin A.; ?alogovi?, Jasa

2011-12-01

299

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.

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

2013-01-01

300

Solar-Cosmic-Ray-Produced Nuclides in Extraterrestrial Matter  

Microsoft Academic Search

There are two main types of cosmic rays that have sufficient energy to induce nuclear reactions -- the galactic cosmic rays (GCR) and solar cosmic rays (also called solar energetic particles). Both types of particles can have production rates and production ratios in the small objects often found in cold and hot deserts that are different from those seen for

Robert C. Reedy

2000-01-01

301

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

2013-10-16

302

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

Microsoft Academic Search

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

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

2008-01-01

303

Benchmarking Radiation Transport Codes for Space Missions  

Microsoft Academic Search

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

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

2008-01-01

304

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

305

Invited Editorial: Radiation exposures of aircrew in high altitude flight  

Microsoft Academic Search

Introduction Background radiation levels in the atmosphere vary in intensity with latitude, altitude and phase of the solar cycle. These background levels are generated primarily by galactic cosmic rays (GCR), consisting of energetic nuclei of all naturally occurring elements, interacting with atmospheric constituents, primarily through atomic and nuclear collisions. Cosmic rays were discovered in 1912, about the same time that

Lawrence W. Townsend

2001-01-01

306

The angular extents of solar\\/interplanetary disturbances and modulation of galactic cosmic rays  

Microsoft Academic Search

From comparisons of solar activity with galactic cosmic ray (GCR) modulation events at 1 AU and in the outer heliosphere, we argue against the suggestion that individual solar eruptions can give rise to major cosmic ray modulation events that span the heliosphere. For the inner heliosphere, we use a sample, covering a ~30-year period, of eruptive flares and confidently associated

E. W. Cliver; H. V. Cane

1996-01-01

307

Radiation shield requirements for manned nuclear propulsion space vehicles  

Microsoft Academic Search

Manned nuclear propulsion space vehicles require radiation shielding to protect the crew from a number of diverse radiation sources: the propulsion system reactor, the Earth's Van Allen radiation belts, anomalously large solar proton events (ALSPEs), and galactic cosmic radiation (GCR). The sources are characterized not only in terms of species and energy spectrum, but also by frequency, duration, and probability

Paul H. Sager

1992-01-01

308

Radiation shield requirements for manned nuclear propulsion space vehicles  

Microsoft Academic Search

Manned nuclear propulsion space vehicles require radiation shielding to protect the crew from a number of diverse radiation sources: the propulsion system reactor, the Earth’s Van Allen radiation belts, anomalously large solar proton events (ALSPEs), and galactic cosmic radiation (GCR). The sources are characterized not only in terms of species and energy spectrum, but also by frequency, duration, and probability

Paul H. Sager

1992-01-01

309

Special applications of gas-cooled reactors  

Microsoft Academic Search

The HTGR technology has been demonstrated by Peach Bottom, Fort St. Vrain, and AVR. Another member of the GCR family is the GCFR. Energy requirements for process heat applications of the HTGR high-temperature nuclear heat source are tabulated. 2 tables. (DLC)

Peinado

1981-01-01

310

Guidelines for Determination of Laboratory Acceptability for Analysis of Volatile Organic Pollutants Collected on Tenax GC (Trade Name) Adsorbent.  

National Technical Information Service (NTIS)

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...

J. T. Bursey R. K. M. Jayanty W. F. Gutknecht

1984-01-01

311

The novel disulfide reductase bis-gamma-glutamylcystine reductase and dihydrolipoamide dehydrogenase from Halobacterium halobium: purification by immobilized-metal-ion affinity chromatography and properties of the enzymes.  

PubMed Central

An NADPH-specific disulfide reductase that is active with bis-gamma-glutamylcystine has been purified 1,900-fold from Halobacterium halobium to yield a homogeneous preparation of the enzyme. Purification of this novel reductase, designated bis-gamma-glutamylcystine reductase (GCR), and purification of halobacterial dihydrolipoamide dehydrogenase (DLD) were accomplished with the aid of immobilized-metal-ion affinity chromatography in high-salt buffers. Chromatography of GCR on immobilized Cu2+ resin in buffer containing 1.23 M (NH4)2SO4 and on immobilized Ni2+ resin in buffer containing 4.0 M NaCl together effected a 120-fold increase in purity. Native GCR was found to be a dimeric flavoprotein of Mr 122,000 and to be more stable to heat when in buffer of very high ionic strength. DLD was chromatographed on columns of immobilized Cu2+ resin in buffer containing NaCl and in buffer containing (NH4)2SO4, the elution of DLD differing markedly in the two buffers. Purified DLD was found to be a heat-stable, dimeric flavoprotein of Mr 120,000 and to be very specific for NAD. The utility of immobilized-metal-ion affinity chromatography for the purification of halobacterial enzymes and the likely cellular function of GCR are discussed. Images

Sundquist, A R; Fahey, R C

1988-01-01

312

Simulation of the radiation exposure in space during a large solar energetic particle event with GEANT4  

Microsoft Academic Search

The radiation field in space is complex due to the various contributing sources and astronauts at the International Space Station (ISS) in low Earth orbit or beyond are exposed to significantly increased doses compared to on ground or in the lower atmosphere. The main sources of the increased radiation level are Galactic Cosmic Ray (GCR) particles, mainly fully charged ions

Daniel Matthiä; Thomas Berger; Monika Puchalska; Guenther Reitz

2010-01-01

313

Modeling spectra of cosmic rays influencing on the ionospheres of the earth and outer planets during solar maximum and minimum  

Microsoft Academic Search

The galactic (GCRs) and anomalous (ACRs) cosmic rays form the lower parts of the planetary ionospheres. For this purpose analytical and numerical spectra for cosmic particles are necessary. The spectra of GCRs and ACRs observed in the Solar system are modulated by the Sun. Our knowledge of GCR modulation in the solar system was greatly enhanced thanks to the heliospheric

M. Buchvarova; P. I. Y. Velinov

2005-01-01

314

Mechanical behaviour of HTR materials: Developments in support of defect assessment, structural integrity and lifetime evaluation  

Microsoft Academic Search

Mod 9Cr–1Mo steel (T91) is a candidate material for pressure vessels and for some internal structures of GCR (Gas Cooled Reactors). In order to validate this choice, it is necessary, firstly to verify that it is able to withstand the planned environmental and operating conditions, and secondly to check if it is covered by the existing design codes, concerning its

O. Ancelet; S. Marie

2010-01-01

315

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...

316

Studies on the Effect of Cloud Coverage and Galactic Cosmic Ray on Stratospheric Moistening  

NASA Astrophysics Data System (ADS)

Increased stratospheric water vapor is one of the significant causes of global warming as increased stratospheric water vapor acts to cool the stratosphere but it warms the underlying troposphere. The sun can influence the clouds by mediating through Galactic cosmic rays (GCR) which controls the nucleation of water droplets in the atmosphere. The role of primary GCR in generating low-level cloud condensation nuclei reflects solar energy back into space affecting the temperature on earth. In the present study, variations of different types of cloud coverage (low, mid and high) are correlated with the intensity of GCR flux and their effects on the stratospheric moistening in the equatorial, mid- latitude and polar region have been investigated for the years 2004 and 2005 using the Aura's Microwave Limb Sounder (MLS) water vapor data, ISCCP cloud data and GCR from neutron monitor observations at Calgary (51.080 N, 245.870 E). The relation between GCR and stratospheric moistening is also investigated in this paper. Additionally, the latitudinal variation of different types of cloud coverage is also studied for the same period. The southern mid-latitudinal region has the highest coverage of low-level cloud, followed by the equatorial region. Both the Polar Regions are highly covered with mid-level cloud. The mid-latitudinal region shows highest coverage of high-cloud, followed by the equatorial region. Lower level clouds exert a large net cooling effect on the climate indicating an inter-relationship between cosmic ray and cloud coverage. However, the mid and high cloud coverage have no significant correlation with GCR flux. The stratospheric moistening is controlled by transport of water vapour from troposphere to stratosphere through the tropopause region and the oxidation of methane within the stratosphere. Water vapour plays a major role in the chemistry and radiative budget of the stratosphere. One possible water vapor source in the stratosphere is the advection of water vapor from lower levels by tropospheric deep convection. Stratospheric moistening is positively correlated with low-level and mid-level cloud coverage, whereas it is less significantly correlated with high-level cloud coverage. It may be interesting to note that stratospheric moistening increases with the increase in GCR, which assimilates the fact that there is a possible connection between cloud coverage and stratospheric moistening in a global perspective.

Maitra, Animesh; Saha, Upal; Das, Saurabh

2012-07-01

317

Functional characterization of transcriptional regulatory elements in the upstream region of the yeast GLK1 gene.  

PubMed Central

The glucokinase gene GLK1 of the yeast Saccharomyces cerevisiae is transcriptionally regulated in response to the carbon source of the growth medium. Northern-blot analysis shows that the GLK1 gene is expressed at a basal level in the presence of glucose, de-repressed more than 6-fold under conditions of sugar limitation and more than 25-fold under conditions of ethanol induction. lacZ fusions of the GLK1 gene promoter were constructed and a deletion analysis was performed in order to identify the cis-acting regulatory elements of the promoter that controls GLK1 gene expression. First, the expression seemed to be mediated mainly by one GCR1 and three stress-responsive element (STRE) activating elements. Secondly, an ethanol repression autoregulation (ERA)/twelve-fold TA repeat (TAB) repressor element was identified within the promoter region of the GLK1 gene. A specific and differential protein binding to the STRE was observed with extracts from de-repressed and repressed cells. No differential binding to the GCR1 or ERA/TAB elements was observed with extracts from de-repressed and repressed cells, but, in both cases, the binding was competed for by an excess of the unlabelled GLK1(GCR1) and GLK1(ERA) sequence. The transcription factors Msn2 and Msn4, which bind to the GLK1 upstream region through the STRE, contribute to inductive activation. The transcription factor Gcr1, which binds through the GCR1 element, contributes to constitutive activation. In order to achieve the severe glucose repression of GLK1, constitutive repressor factors acting through the ERA/TAB element must counteract constitutive activation generated by Gcr1 binding to the GCR1 element. Full expression of the GLK1 gene is produced by inductive activation of three STRE when Msn2 and Msn4 proteins are translocated to the nucleus by covalent modification. The combinatorial effect of the entire region leads to the regulated transcription of GLK1, i.e., silent in media with glucose and other preferred carbon sources, such as fructose or mannose, and increased levels of expression upon glucose depletion.

Herrero, P; Flores, L; de la Cera, T; Moreno, F

1999-01-01

318

First Results From the Martian Radiation Environment Experiment MARIE  

NASA Astrophysics Data System (ADS)

The Martian Radiation Environment Experiment (MARIE), aboard the 2001 Mars Odyssey spacecraft, is returning the first detailed radiation data from Mars orbit. Characterization of the Martian radiation environment is a necessary precursor to eventual human exploration of Mars. MARIE, which consists primarily of an 8-element silicon detector telescope, is providing high-quality measurements of Solar Energetic Particles (SEP) from a unique vantage point, and is also able to measure a significant portion of the spectrum of Galactic Cosmic Rays (GCR). The GCR are composed of atomic nuclei with kinetic energies ranging from tens of MeV per nucleon to hundreds of GeV per nucleon and higher. Energy distributions typically peak in the region of several hundred MeV per nucleon. These highly charged and energetic particles can penetrate tens of centimeters of matter, including tissue and practical depths of spacecraft shielding. The combination of high energy and high ionization associated with heavy nuclei in the GCR make these particles much more effective in causing biological damage than a comparable dose of sparsely-ionizing radiation such as muons or X-rays. These particles therefore present a potentially serious long-term health risk to astronauts, particularly on missions outside the protection of the geomagnetosphere. At Mars, the GCR spectrum is expected to be substantially the same as seen at Earth, modulated slightly by variations in the solar magnetic field. The spectrum of SEP tends to be dominated by low-energy protons; though less exotic than heavy ions in the GCR, these particles, produced in Coronal Mass Ejections, pose the risk of acute radiation exposure, owing to the high fluxes that are often generated. SEP spectra for a given CME may be entirely different at Earth and Mars, for a variety of reasons. MARIE has been operational in Mars orbit since March 2002. Several solar events have been observed, in addition to GCR ions. We will present dosimetric results as well as preliminary particle spectra from SEP and GCR.

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

2002-12-01

319

Dependence of the 27-day variation of cosmic rays on the global magnetic field of the Sun  

NASA Astrophysics Data System (ADS)

We show that the higher range of the heliolongitudinal asymmetry of the solar wind speed in the positive polarity period (A > 0) than in the negative polarity period (A < 0) is one of the important reasons of the larger amplitudes of the 27-day variation of the galactic cosmic ray (GCR) intensity in the period of 1995-1997 (A > 0) than in 1985-1987 (A < 0). Subsequently, different ranges of the heliolongitudinal asymmetry of the solar wind speed jointly with equally important corresponding drift effect are general causes of the polarity dependence of the amplitudes of the 27-day variation of the GCR intensity. At the same time, we show that the polarity dependence is feeble for the last unusual minimum epoch of solar activity 2007-2009 (A < 0); the amplitude of the 27-day variation of the GCR intensity shows only a tendency of the polarity dependence. We present a three dimensional (3-D) model of the 27-day variation of GCR based on the Parker's transport equation. In the 3-D model is implemented a longitudinal variation of the solar wind speed reproducing in situ measurements and corresponding divergence-free interplanetary magnetic field (IMF) derived from the Maxwell's equations. We show that results of the proposed 3-D modeling of the 27-day variation of GCR intensity for different polarities of the solar magnetic cycle are in good agreement with the neutron monitors experimental data. To reach a compatibility of the theoretical modeling with observations for the last minimum epoch of solar activity 2007-2009 (A < 0) a parallel diffusion coefficient was increased by ˜40%.

Modzelewska, R.; Alania, M. V.

2012-09-01

320

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

321

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

322

Galactic Cosmic Ray Intensities Reach Record Levels in 2009  

NASA Astrophysics Data System (ADS)

Recent data from ACE show that during the spring and summer of 2009 the galactic cosmic ray (GCR) intensity at ~100 to ~500 MeV/nuc (near the peak in the spectrum at 1 AU) reached the highest intensities of the space era. During mid-2007 the GCR intensities of Be to Ni (4 ? Z ? 28) had apparently leveled off at intensities comparable to those measured in the 1976-77 and 1997-1998 solar minima, and the onset of new solar activity was expected in 2008. Instead, solar-minimum conditions continued, and the GCR intensity began to increase again in early 2008. During the second quarter of 2009 the 120-470 MeV/nuc GCR Fe intensity reached 19% ± 1% above the 1997-1998 solar-minimum level, with similar increases in other species. Comparisons with earlier spacecraft and neutron-monitor data show conclusively that the GCR intensities in the spring and summer of 2009 are the highest of the space era. However, when viewed in the context of the long-term Be-10 record, the space era has until now experienced a below-average cosmic-ray intensity. The record-setting intensity levels are likely due to a combination of factors that include the weakened interplanetary magnetic field strength, the reduced solar wind speed and dynamic pressure, and the extended solar minimum conditions. In addition, during alternate solar minima, including the present one, the drift pattern of cosmic rays in the heliosphere is sensitive to the tilt of the interplanetary magnetic current sheet, which was still inclined at ~20° in mid-2009. If the current sheet tilt declines further before the onset of new solar activity, it is likely that the GCR intensity will reach even higher levels. This paper will compare the 2009 cosmic ray intensities with those from the past ~50 years and with the long-term archival record, summarize the role of the various solar-wind parameters in modulating the near-Earth cosmic ray intensity, and discuss the implications of the 2009 cosmic-ray intensities for estimates of the interplanetary radiation dose.

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

2009-12-01

323

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

324

The dorsal lateral geniculate nucleus of Tupaia glis: a Golgi, Nissl and acetylcholinesterase study.  

PubMed

Morphology of neurons and afferent axons in the dorsal lateral geniculate nucleus (dLGN) of the tree shrew (Tupaia glis) was studied using Golgi-Kopsch impregnated and Nissl stained material. Staining of acetylcholinesterase (AChE) could inform about the distribution of this enzyme in the tree shrew's dLGN. The results can be summarized as follows: 1. Two classes of neurons can be identified: class-I-neurons and class-II-neurons. Class-I-neurons correspond to geniculo-cortical relay neurons (GCR-neurons) and class-II-neurons correspond to local interneurons (I-neurons). 2. Class-I-neurons differ in their morphology depending on their laminar position. Tufted neurons with clusters of grape-like appendages in their branching zones resembling X-cells in the cat's dLGN are localized in the external laminae 5 and 4. In the superficial lamina 6 the dendrite domains of GCR-neurons are flattened and elongated. Dendrites seem not to penetrate laminar borders. The cells in layer 3 have the smallest soma and radiate dendrites. There is some evidence that GCR-neurons in this lamina represent W-cells (Carey et al., 1979). GCR-neurons in laminae 2 and 1 (innermost laminae) have the biggest somata. Their dendritic branching patterns make it difficult to classify the cells into tufted or radiate. Branching zones are rather smooth. These cells seem to be good candidates for Y-cells. 3. I-neurons could be identified in all laminae. Their dendrites preferentially take a dorso-ventral course. Only axon initial segments of these neurons were visible in Golgi preparations. 4. GCR-neurons and I-neurons could also be identified in Nissl preparations. The ratio GCR-neurons: I-neurons is about 10:1, i.e. 10% of all neurons are I-neurons. 5. In Golgi preparations some types of axons were impregnated. Type-1-axons resemble cortical afferents of other mammalian species. Type-2-axons (2a, 2b, 2c) do not leave single laminae in our material. Considering branching characteristics of their terminal zones, this finding could be a reference for their retinal origin. 6. Laminae 5, 4, 2, and 1 have a remarkable higher content of AChe than the laminae 6 and 3. The low level of ACHE in lamina 3 of the tree shrew's dLGN corresponds to the less activity of ACHE in the laminae 4 and 5 of Galago senegalensis (Fitzpatrick and Diamond, 1979), which like lamina 3 in Tupaia's dLGN project to layer I of the visual cortex (Carey et al., 1979). PMID:7240727

Brauer, K; Werner, L; Winkelmann, E; Lüth, H J

1981-01-01

325

Production Profiles of Nuclides by Galactic-Cosmic-Ray Particles in the Tops of Lunar Rocks  

NASA Astrophysics Data System (ADS)

The determination of the flux and spectral shape of solar-cosmic-ray (SCR) particles from measurements of cosmogenic nuclides in lunar samples requires many pieces of information. An important part of the analysis is the correction of the measured nuclide concentration for the contribution by galactic-cosmic-ray (GCR) particles in the surface layers, where SCR production is important. Usually the GCR contribution is inferred from the concentration of the nuclide measured at a depth where SCR production is negligible and using a GCR production profile to extrapolate back to the surface. The shapes of these GCR profiles were found to be important for neon and argon [1] and ^10Be [2] in lunar rock 68815. Better determination of this near-surface GCR production profile would improve this important correction. As almost all nuclides have some production by SCR particles, it is hard to determine experimentally this GCR profile. The GCR production profile in the top of lunar rock 68815 was calculated using the Los Alamos Monte Carlo LAHET Code System (LCS). LCS has yielded calculated production rates that almost always are in good agreement with cosmogenic- nuclide measurements in meteorites [3,4]. The fluxes of protons and neutrons in rock 68815 was calculated for 1 g/cm^2 layers down to a depth of 25 g/cm^2 and with a coarser depth mesh to a depth of 500 g/cm^2 with LCS. These fluxes for each layer were then multiplied by the relevant cross sections and integrated over energy for eight nuclides: ^10Be, ^14C, ^21Ne, ^22Ne, ^26Al, ^36Cl, ^38Ar, and ^53Mn. The calculated production profiles below about 30 g/cm^2 agree well with lunar core measurements. All the cosmogenic nuclides studied have GCR production profiles that increase from the surface of the Moon to a maximum at depths of ~20-50 g/cm^2 and then decrease with increasing depth. The amount of this increase varies considerably, with products made by higher-energy particles and by protons having less increase in production rate with depth. The amount of the increase from the surface to depths of 10 or 20 g/cm^2 correlates with the depth of the peak production rate. The highest-energy product in this study, ^10Be, has a peak production rate near ~20 g/cm^2 and has ratios of the production rate at 0-1 g/cm^2 to those at 9-10 and 19-20 g/cm^2 of 0.965 and 0.940 respectively. With typical lunar saturation activities of ~12 dpm/kg, the surface has a ^10Be activity due only to GCR particles that is ~1 dpm/kg less than that near the production peak. The flat ^10Be activities measured in lunar samples [2] would thus imply a SCR contribution about equal to this small GCR difference, restricting the spectral shapes of solar protons that made ^10Be to those with few high-energy particles. For the composition of lunar rock 68815, the nuclides with the steepest GCR profiles were ^26Al and ^38Ar, with ratios of production rates at 0-1 g/cm^2 to those at 9-10 and 19-20 g/cm^2 of about 0.79 and 0.71 respectively, and with peak production rates near ~50 g/cm^2. The production ratios for these depths were, respectively, about 0.82 and 0.74 for ^53Mn and ^14C, about 0.84 and 0.76 for ^36Cl, and 0.88 and 0.84 for ^21Ne and ^22Ne. These calculations for the production of nuclides in the top layers of lunar rocks by GCR particles show that there are increases with depth down to ~20-50 g/cm^2 and that the amount of the increase varies with the nuclear reactions making the nuclide. Experimental confirmation of these calculated GCR production profiles should be made, possibly with 35-day ^37Ar in lunar rocks from a mission like Apollo 16 that had few solar particle events prior to it. This work was supported by NASA and done under the auspices of the U.S. Department of Energy. References: [1] Garrison D. G. et al. (1993) LPS XXIV, 521. [2] Nishiizumi K. et al. (1988) Proc. LSPC 18th, 79. [3] Masarik J. and Reedy R. C. (1993) LPS XXIV, 937. [4] Reedy R. C. et al. (1993) LPS XXIV, 1195.

Masarik, J.; Reedy, R. C.

1993-07-01

326

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

PubMed

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. PMID:17689491

Banerjee, Soma; Sikdar, Nilabja; Myung, Kyungjae

2007-07-31

327

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

328

Physical conditions and molecular chemistry of the Central Molecular Zone  

NASA Astrophysics Data System (ADS)

We discuss the physical conditions of the different kineniatical components of the Central Molecular Zone. In particular we compare the properties of the clouds moving with in elongated orbits along the Galactic bar with those of the well-known Galactic center ring (GCR) clouds (Sgr A, Sgr B2,...). We show that all the components contain dense clouds that can withstand the tidal shear. The SiO abundance in the clouds with non-circular velocities is high (~ 10-8), in perfect agreement with that of the GCR clouds. We discuss the role of the UV radiation and C-shocks in the heating of the neutral gas and the high abundances of some molecules like SiO. The SiO emission in the clouds moving in elongated trajectories is probably due to the cloud collisions expected in the inner regions of a bar.

Rodríguez-Fernández, Nemesio J.

2006-12-01

329

Light ion components of the galactic cosmic rays: nuclear interactions and transport theory.  

PubMed

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 ion induced reactions. In the primary GCR, 4He is the most abundant nucleus after 1H. However, there are also a substantial fluxes of 2H and 3He. 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 fragmentation. 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. PMID:11540375

Cucinotta, F A; Townsend, L W; Wilson, J W; Shinn, J L; Badhwar, G D; Dubey, R R

1996-01-01

330

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

331

Variations in surface beryllium-7 concentration with solar activity  

NASA Astrophysics Data System (ADS)

Be-7 radionuclide half life 53 3 days is produced by nuclear interactions of galactic cosmic rays GCR with N and O nuclei in the upper atmosphere It is a potentially useful tracer of atmospheric air mass motions The Be-7 production rate varies with the solar activity because GCR in the heliosphere are modulated by the solar magnetic field carried out by the solar wind plasma Be-7 produced in the upper atmosphere is transported by complex atmospheric processes and falls to the Earth s surface We analyzed the long-term data of Be-7 concentration in surface air in Japan and tried to study whether the variations in the Be-7 concentration are associated with the 11-year cycle of solar activity

Yoshimori, M.

332

Emerging Radiation Health-Risk Mitigation Technologies  

NASA Astrophysics Data System (ADS)

Past space missions beyond the confines of the Earth's protective magnetic field have been of short duration and protection from the effects of solar particle events was of primary concern. The extension of operational infrastructure beyond low-Earth orbit to enable routine access to more interesting regions of space will require protection from the hazards of the accumulated exposures of Galactic Cosmic Rays (GCR). There are significant challenges in providing protection from the long-duration exposure to GCR: the human risks to the exposures are highly uncertain and safety requirements places unreasonable demands in supplying sufficient shielding materials in the design. A vigorous approach to future radiation health-risk mitigation requires a triage of techniques (using biological and technical factors) and reduction of the uncertainty in radiation risk models. The present paper discusses the triage of factors for risk mitigation with associated materials issues and engineering design methods.

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

2004-02-01

333

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

334

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

335

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

PubMed Central

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 to maintain 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; Myung, Kyungjae

2007-01-01

336

Galactic cosmic ray abundances and spectra behind defined shielding.  

PubMed

LET spectra have been measured for lunar missions and for several near Earth orbits ranging from 28 degrees to 83 degrees inclination. In some of the experiments the flux of GCR was determined separately from contributions caused by interactions in the detector material. Results of these experiments are compared to model calculations. The general agreement justifies the use of the model to calculate GCR fluxes. The magnitude of variations caused by solar modulation, geomagnetic shielding, and shielding by matter determined from calculated LET spectra is generally in agreement with experimental data. However, more detailed investigations show that there are some weak points in modeling solar modulation and shielding by material. These points are discussed in more detail. PMID:11540030

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

1994-10-01

337

Cycling in the amplitudes of the 27-day variations of the galactic cosmic rays intensity and solar activity parameters  

NASA Astrophysics Data System (ADS)

We ponder on the 27-day variation of the galactic cosmic ray (GCR) intensity in different epochs of solar activity. Analyzing a long period changes (1958-2009) of the 27-day variation of the galactic cosmic rays intensity (using neutron monitor data), solar activity, solar wind and geomagnetic activity parameters we found a clear recurrence in the temporal changes of the amplitudes of the 27-day variation of the GCR and in some parameters of solar activity and solar wind. We distinguish evidently established reappearance (cycling) with duration of three Carrington rotations period (3-CRP). We suppose that a creation of the 3-CRP could be related with the Sun's differential rotation causing a conversion of the Sun's poloidal magnetic field into the toroidal and vice versa.

Gil, Agnieszka; Alania, Michael

338

Cycling changes in the amplitudes of the 27-day variation of the galactic cosmic rays intensity  

NASA Astrophysics Data System (ADS)

We study the 27-day variation of the galactic cosmic ray intensity (GCR) in different epochs of solar activity. Analysing a long period changes (1958-2009) of the 27-day variation of the galactic cosmic rays intensity, solar activity, solar wind and geomagnetic activity parameters we found a clear recurrence in the temporal changes of the amplitudes of the 27-day variation of the GCR and in some parameters of solar activity and solar wind. For being precise, we recognize noticeably established recurrence (cycling) with duration of three Carrington rotations period (3-CRP). We assume that a creation of the 3-CRP could be related with the Sun's differential rotation causing a conversion of the Sun's poloidal magnetic field into the toroidal.

Gil, Agnieszka; Alania, Michael V.

2010-05-01

339

Development of selective amplifier genes for hematopoietic stem cell gene therapy  

Microsoft Academic Search

To overcome the low efficiency of gene transfer into hematopoietic stem cells, we developed a novel system for selective expansion\\u000a of transduced cells. The system utilizes “SAGs (selective amplifier genes)” which encode fusion proteins consisting of a growth-signal\\u000a generator and its molecular switch. First, a fusion gene encoding a chimeric receptor between G-CSF receptor (GCR) and hormone-binding\\u000a domain of estrogen

Keiya Ozawa; Yutaka Hanazono; Akihiro Kume; Takeyuki Nagashima; Yasuji Veda; Keiji Terao; Mamoru Hasegawa

2002-01-01

340

On the origin of the light elements (Z<6)  

Microsoft Academic Search

The author reviews the status of our understanding of nucleosynthesis of the light nuclei (Z<6). The standard view today is that these elements are, for the most part, generated by two different processes: first, thermonuclear reactions in the early universe (big-bang nucleosynthesis or (BBN), and second, galactic cosmic-ray-induced spallation reactions (GCR) in cold interstellar atoms. A third contribution comes from

Hubert Reeves

1994-01-01

341

On the origin of the light elements ([ital Z][lt]6)  

Microsoft Academic Search

The author reviews the status of our understanding of nucleosynthesis of the light nuclei ([ital Z][lt]6). The standard view today is that these elements are, for the most part, generated by two different processes: first, thermonuclear reactions in the early universe (big-bang nucleosynthesis or (BBN), and second, galactic cosmic-ray-induced spallation reactions (GCR) in cold interstellar atoms. A third contribution comes

Reeves

1994-01-01

342

Cosmic Rays During the Most-Recent Sunspot Minimum  

NASA Astrophysics Data System (ADS)

During the sunspot minimum between solar cycles 23 and 24, galactic cosmic rays (GCR) reached the highest intensity seen during the spacecraft era. This was due in part to the lower open solar magnetic flux and slower solar wind seen during this period, compared to previous solar minima. The effects of cosmic-ray drifts along the heliospheric current sheet (HCS) has yet to be completely understood; but it is interesting to note that while the HCS was generally not as flat as one might expect given the very quiet Sun, it was at its flattest when the GCR intensity was at its highest. This is important because during this solar magnetic cycle, cosmic-ray protons drift into the heliosphere along the HCS. And, despite the unusually high GCR intensity during this solar minimum, the intensity of anomalous cosmic rays (ACR) was NOT seen to be as high as in previous sunspot minima. Moreover, the GCR electron intensity at the two Voyager spacecraft, which are both approaching the heliopause, is seen to be quite different. These observations lead to important questions regarding the transport of cosmic rays in the heliospheric magnetic field, which originates at the Sun. Particularly important is the transport of cosmic rays across the magnetic field, the role of the heliosheath in cosmic-ray modulation, drifts at the HCS, and the differences between ACRs and GCRs. In this talk, we will review our understanding of cosmic-ray transport in the solar and heliospheric magnetic field and discuss how observations will help resolve these recent puzzles and give constraints on transport parameters.

Giacalone, Joe; Jokipii, Jack; Kota, Jozsef

2012-07-01

343

A comparison of clinician-rated neuropsychological and self-rated cognitive assessments in patients with asthma and rheumatologic disorders.  

PubMed

Although data are mixed, asthma and rheumatologic conditions may be associated with cognitive impairment. Medications may play a role because corticosteroids are associated with memory impairment. Therefore, an easily administered assessment of cognition would be useful in these patients. We assessed relationships between self-rated and clinician-rated cognitive performance and mood in patients with asthma and rheumatologic diseases. Participants included 31adults treated for asthma or rheumatologic disorders (17 receiving chronic prednisone therapy, and 14 not receiving prednisone). An objective assessment of a variety of cognitive domains was administered through clinician and patient-rated assessments of cognition. Composite scores for the objective (Global Clinical Rating [GCR]) and subjective (Neuropsychological Impairment Scale: Global Measure of Impairment [GMI]) measures of cognition were derived. Depression was assessed with the 17-item Hamilton Rating Scale for Depression (HRSD-17). A linear regression was conducted with GMI scores as dependent variable and GCR, HRSD-17 scores, and prednisone-use status, as independent variables. Significant differences between prednisone-treated patients and other patients were observed on the GCR, GMI, and HRSD-17. In the regression analysis, HRSD-17 scores, but not GCR scores, significantly predicted GMI scores. Prednisone-treated patients had higher levels of depressive symptoms and subjective and objective cognitive deficits than those not taking prednisone. In the combined patient groups, subjective cognitive assessment was more strongly related to depressive symptoms than objective cognition. Findings suggest physicians should be aware of the potential for cognitive deficits in patients taking corticosteroids and, when appropriate, should consider the use of objective neurocognitive tests or neuropsychology consultation to better characterize its presence and severity. PMID:23484893

Frol, Alan B; Vasquez, Aracely; Getahun, Yonatan; Pacheco, Maria; Khan, David A; Brown, E Sherwood

344

Molecular mechanisms of glucocorticoid action and selective glucocorticoid receptor agonists.  

PubMed

Glucocorticoids (GC) are the most common used anti-inflammatory and immunosuppressive drugs in the treatment of rheumatic and other inflammatory diseases. Their therapeutic effects are considered to be mediated by four different mechanisms of action: the classical genomic mechanism of action caused by the cytosolic glucocorticoid receptor (cGCR); secondary non-genomic effects which are also initiated by the cGCR; membrane-bound glucocorticoid receptor (mGCR)-mediated non-genomic effects; non-specific, non-genomic effects caused by interactions with cellular membranes. The classical, genomic mechanism of GC-action can be divided into two processes: "transrepression", which is responsible for a large number of desirable anti-inflammatory and immunomodulating effects, and "transactivation" which is associated with frequently occurring side effects as well as with some immunosuppressive activities [Ehrchen, J., Steinmuller, L., Barczyk, K., Tenbrock, K., Nacken, W., Eisenacher, M., Nordhues, U., Sorg, C., Sunderkotter, C., Roth, J., 2007. Glucocorticoids induce differentiation of a specifically activated, anti-inflammatory subtype of human monocytes. Blood 109, 1265-1274]. Great efforts have been made to diminish glucocorticoid-induced adverse effects, but the improvement of conventional glucocorticoids has almost reached its limits. As a consequence, new variations of the conventional "good old drugs" are being tested and nitro-steroids and long circulating liposomal glucocorticoids indeed show promising results. Nevertheless, crux of the matter should be the design of qualitatively new drugs, such as selective glucocorticoid receptor agonists (SEGRAs). These innovative steroidal or non-steroidal molecules induce transrepression, while transactivation processes are less affected. First reports on two different GCR ligands, A276575 and ZK216348, show promising results. Here, we review the above-mentioned mechanisms of glucocorticoid action and give particular attention to the development of optimized glucocorticoids and SEGRAs. PMID:17630118

Stahn, Cindy; Löwenberg, Mark; Hommes, Daniel W; Buttgereit, Frank

2007-06-02

345

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

Microsoft Academic Search

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

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

2004-01-01

346

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

Microsoft Academic Search

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

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

2004-01-01

347

Optimized Shielding for Space Radiation Protection  

Microsoft Academic Search

Future deep space mission and International Space Station exposures will be dominated by the high-charge and -energy (HZE) ions of the Galactic Cosmic Rays (GCR). A few mammalian systems have been extensively tested over a broad range of ion types and energies. For example, C3H10T1\\/2 cells, V79 cells, and Harderian gland tumors have been described by various track-structure dependent response

J. W. Wilson; F. A. Cucinotta; M.-H. Y. Kim; W. Schimmerling

2000-01-01

348

The 22-Year Hale Cycle in Cosmic Ray Flux - Evidence for Direct Heliospheric Modulation  

NASA Astrophysics Data System (ADS)

The ability to predict times of greater galactic cosmic ray (GCR) fluxes is important for reducing the hazards caused by these particles to satellite communications, aviation, or astronauts. The 11-year solar-cycle variation in cosmic rays is highly correlated with the strength of the heliospheric magnetic field. Differences in GCR flux during alternate solar cycles yield a 22-year cycle, known as the Hale Cycle, which is thought to be due to different particle drift patterns when the northern solar pole has predominantly positive (denoted as qA>0 cycle) or negative (qA<0) polarities. This results in the onset of the peak cosmic-ray flux at Earth occurring earlier during qA>0 cycles than for qA<0 cycles, which in turn causes the peak to be more dome-shaped for qA>0 and more sharply peaked for qA<0. In this study, we demonstrate that properties of the large-scale heliospheric magnetic field are different during the declining phase of the qA<0 and qA>0 solar cycles, when the difference in GCR flux is most apparent. This suggests that particle drifts may not be the sole mechanism responsible for the Hale Cycle in GCR flux at Earth. However, we also demonstrate that these polarity-dependent heliospheric differences are evident during the space-age but are much less clear in earlier data: using geomagnetic reconstructions, we show that for the period of 1905 - 1965, alternate polarities do not give as significant a difference during the declining phase of the solar cycle. Thus we suggest that the 22-year cycle in cosmic-ray flux is at least partly the result of direct modulation by the heliospheric magnetic field and that this effect may be primarily limited to the grand solar maximum of the space-age.

Thomas, S. R.; Owens, M. J.; Lockwood, M.

2013-07-01

349

Radiation Measured with Different Dosimeters for ISS-Expedition 18-19/ULF2 on Board International Space Station during Solar Minimum  

NASA Astrophysics Data System (ADS)

Radiation field of particles in low Earth orbit (LEO) is mainly composed of galactic cosmic rays (GCR), solar energetic particles and particles in SAA (South Atlantic Anomaly). GCR are modulated by solar activity, at the period of solar minimum activity, GCR intensity is at maximum and the main contributor for space radiation is GCR. At present for space radiation measurements conducted by JSC (Johnson Space Center) -SRAG (Space Radiation Analysis Group), the preferred active dosimeter sensitive to all LET (Linear Energy Transfer) is the tissue equivalent proportional counter (TEPC); the preferred passive dosimeters are thermoluminescence dosimeters (TLDs) and optically stimulated luminescence dosimeters (OSLDs) sensitive to low LET as well as CR-39 plastic nuclear track detectors (PNTDs) sensitive to high LET. For the method using passive dosimeters, radiation quantities for all LET can be obtained by combining radiation results measured with TLDs/OSLDs and CR-39 PNTDs. TEPC, TLDs/OSLDs and CR-39 detectors were used to measure the radiation field for the ISS (International Space Station) -Expedition 18-19/ULF2 space mission which was conducted from 15 November 2008 to 31 July 2009 -near the period of the recent solar minimum activity. LET spectra (differential and integral fluence, absorbed dose and dose equivalent) and radiation quantities were measured for positions TEPC, TESS (Temporary Sleeping Station, inside the polyethylene lined sleep station), SM-P 327 and 442 (Service Module -Panel 327 and 442). This paper presents radiation LET spectra measured with TEPC and CR-39 PNTDs and radiation dose measured with TLDs/OSLDs as well as the radiation quantities combined from results measured with passive dosimeters.

Zhou, Dazhuang

350

Fission or fusion for Mars missions - Expectations and challenges  

Microsoft Academic Search

A fission-based system in the form of the Gas Core Nuclear Rocket (GCR) and a laser-driven inertial fusion system that utilizes a self-generated magnetic field (MICF) are compared as potential propulsion systems for manned planetary travel. The first generates thrust by a hydrogen propellant that is heated by radiation emitted from a critical reactor with a uranium fuel in plasma

Terry Kammash

1993-01-01

351

Status of experimental data base development relevant to spaceradiation transport and protection  

SciTech Connect

This report describes the highlights and progress made in aprogram of measurements studying radiation transport through materials ofinterest to NASA. All measurements were preformed at acceleratorfacilities, primarily using GCR-like heavy-ion beams incident uponvarious elemental and composite targets. Both primary and secondaryparticles exiting the target were measured. The secondary particlesinclude both charged particles and neutrons. These measurements serve asuseful benchmarks and input to transport model calculations.

Heilbronn, Lawrence H.; Guetersloh, Stephen; Zeitlin, Cary; Miller, Jack

2004-04-01

352

Effect of cosmic rays on atmospheric pressure under mountain conditions  

Microsoft Academic Search

The phenomenological model of condensation interaction between galactic cosmic rays (GCRs) and water vapor, which makes it\\u000a possible to estimate atmospheric pressure variations at different altitudes with changing GCR flux, has been developed. It\\u000a has been indicated that pressure should increase at all altitudes in the considered interval (0–5 km above sea level) during\\u000a Forbush decreases. Therefore, the correlation between

M. B. Bogdanov; A. N. Surkov; A. V. Fedorenko

2006-01-01

353

Determination of the flux and energy distribution of energetic solar protons in the past 2 Myr using lunar rock 68815  

Microsoft Academic Search

Cosmogenic [sup 21]Ne, [sup 22]Ne, [sup 38]Ar, and [sup 3]He produced by nuclear interactions of energetic (>10 MeV) solar protons were determined in 11 depth samples of lunar rock 68815. Concentrations of these proton-produced, SCR nuclides smoothly decrease from the rock surface down to 4.3 cm, where a galactic cosmic ray (GCR) component dominates. The cosmogenic [sup 21]Ne\\/[sup 22]Ne isotopic

M. N. Rao; D. H. Garrison; D. D. Bogard; R. C. Reedy

1994-01-01

354

Determination of the flux and energy distribution of energetic solar protons in the past 2 Myr using lunar rock 68815  

Microsoft Academic Search

Cosmogenic 21 Ne, 22 Ne, 38 Ar, and 3 He produced by nuclear interactions of energetic (>10 MeV) solar protons were determined in 11 depth samples of lunar rock 68815. Concentrations of these proton-produced, SCR nuclides smoothly decrease from the rock surface down to 4.3 cm, where a galactic cosmic ray (GCR) component dominates. The cosmogenic 21 Ne \\/ 22

M. N. Rao; D. H. Garrison; D. D. Bogard; R. C. Reedy

1994-01-01

355

Adequate phenylalanine synthesis mediated by G protein is critical for protection from UV radiation damage in young etiolated Arabidopsis thaliana seedlings  

Microsoft Academic Search

Etiolated Arabidopsis thaliana seedlings, lacking a func- tional prephenate dehydratase1 gene (PD1), also lack the ability to synthesize phenylalanine (Phe) and, as a conse- quence, phenylpropanoid pigments. We find that low doses of ultraviolet (UV)-C (254 nm) are lethal and low doses of UV-Bcauseseveredamagetoetiolatedpd1mutants,butnot to wild-type (wt) seedlings.Furthermore,exposure to UV-C is lethal to etiolated gcr1 (encoding a putative G protein-

KATHERINE M. WARPEHA; JACK GIBBONS; ANDREW CAROL; JAMES SLUSSER; ROGER TREE; WILLIAM DURHAM; LON S. KAUFMAN

2008-01-01

356

Influence of spacecraft shielding structures on Galactic Cosmic ray-induced soft error rate  

Microsoft Academic Search

Through the use of the Geant4 Radiation Analysis for Space (GRAS) Monte Carlo tool, we present new results on the impact of shielding composition on spacecraft electronics Soft Error Rate (SER) induced by Galactic Cosmic Rays (GCR). The comparison with the aluminum-equivalent approach is performed using both G4\\/GRAS and CREME96 tool on a heterogeneous set of representative devices. In particular

Marco Silvestri; Emanuele Tracino; Roberto Destefanis; Cesare Lobascio; Giovanni Santin; Philippe Calvel

2011-01-01

357

Impact of Spacecraft-Shell Composition on 1 GeV\\/Nucleon ${}^{56}$ Fe Ion-Fragmentation and Dose Reduction  

Microsoft Academic Search

Through the use of experimental data and Monte Carlo simulations we investigate the shielding properties of spacecraft-shell compositions exposed to 1 GeV\\/nucleon ${}^{56}$ Fe ions, representative of the worst part of the Galactic Cosmic Ray (GCR) spectrum. Through the use of the Geant4 Radiation Analysis for Space (GRAS) tool, the dose reduction and the ${}^{56}$Fe-fragmentation induced by those structures currently

Marco Silvestri; Emanuele Tracino; Mauro Briccarello; Maurizio Belluco; Roberto Destefanis; Cesare Lobascio; Marco Durante; Giovanni Santin; Ronald D. Schrimpf

2011-01-01

358

MCNP6 Cosmic-Source Option  

SciTech Connect

MCNP is a Monte Carlo radiation transport code that has been under development for over half a century. Over the last decade, the development team of a high-energy offshoot of MCNP, called MCNPX, has implemented several physics and algorithm improvements important for modeling galactic cosmic-ray (GCR) interactions with matter. In this presentation, we discuss the latest of these improvements, a new Cosmic-Source option, that has been implemented in MCNP6.

McKinney, Gregg W [Los Alamos National Laboratory; Armstrong, Hirotatsu [Los Alamos National Laboratory; James, Michael R [Los Alamos National Laboratory; Clem, John [University of Delaware, BRI; Goldhagen, Paul [DHS, National Urban Security Technology Laboratory

2012-06-19

359

Galactic Cosmic Rays and the Environment  

Microsoft Academic Search

SH.3.6.14 Galactic Cosmic Rays and the Environment G. Cini Castagnoli, G. Bonino, P. Della Monica, C. Taricco Istituto di Cosmogeofisica, CNR, Corso Fiume 4, 10133 Torino, Italy and Dipartimento di Fisica Generale, Università di Torino, Via P. Giuria 1, 10125 Torino Recently Svensmark and Friis-Christensen (1997) reported an indication that the Galactic Cosmic Rays (GCR) modulated by the solar wind

G. Cini Castagnoli

1999-01-01

360

Friction and wear behavior of SUS 304 austenitic stainless steel against Al 2O 3 ceramic ball under relative high load  

Microsoft Academic Search

Friction and wear behaviors of SUS 304 austenitic stainless steel (ASS) disc against Al2O3 ceramic ball and GCr15 bearing steel ball, respectively, were studied using a Cameron-Plint TE67 pin-on-disc tester. The tests were performed under 5–50N loads and 0.06–0.19m\\/s sliding speed. Results showed that there was a gestating period before the friction coefficient increased rapidly as the normal load was

Meng Hua; Wei Xicheng; Li Jian

2008-01-01

361

Cosmic Rays During the Most-Recent Sunspot Minimum  

NASA Astrophysics Data System (ADS)

During the sunspot minimum between solar cycles 23 and 24, galactic cosmic rays (GCR) reached the highest intensity seen during the spacecraft era. This was due in part to the lower open solar magnetic flux and slower solar wind seen during this period, compared to previous solar minima. The effects of cosmic-ray drifts along the heliospheric current sheet (HCS) has yet to be completely understood; but it is interesting to note that while the HCS was generally not as flat as one might expect given the very quiet Sun, it was at its flattest when the GCR intensity was at its highest. This is important because during this solar magnetic cycle, cosmic-ray protons drift into the heliosphere along the HCS. And, despite the unusually high GCR intensity during this solar minimum, the intensity of anomalous cosmic rays (ACR) was NOT seen to be as high as in previous sunspot minima. Moreover, the GCR electron intensity at the two Voyager spacecraft, which are both approaching the heliopause, is seen to be quite different. These observations lead to important questions regarding the transport of cosmic rays in the heliospheric magnetic field, which originates at the Sun. Particularly important is the transport of cosmic rays across the magnetic field, the role of the heliosheath in cosmic-ray modulation, drifts at the HCS, and the differences between ACRs and GCRs. In this talk, we will review our understanding of cosmic-ray transport in the solar and heliospheric magnetic field and discuss how observations will help resolve these recent puzzles and give constraints on transport parameters.

Giacalone, J.; Jokipii, J. R.; Kota, J.

2011-12-01

362

Tribological behavior and structural change of the LB film of MoS 2 nanoparticles coated with dialkyldithiophosphate  

Microsoft Academic Search

The LB film of MoS2 nanoparticles coated with dialkyldithiophosphate (DDP) was prepared on a copper-coated glass substrate. The tribological behavior of the surface-modified MoS2 nanoparticle LB film against GCr15 bearing steel (SAE 52100) was evaluated with a one-way reciprocating friction tester, and the structural change of the LB film during rubbing process was investigated with a Fourier transform infrared (FTIR)

Laigui Yu; Pingyu Zhang; Zuliang Du

2000-01-01

363

Cytochemical studies in Indian childhood cirrhosis  

Microsoft Academic Search

Summary  The histochemical study of liver bropsy in Indian childhood cirrhosis showed a progressive diminution of orthochromatic, DCR,\\u000a nuclear parachromatin, perichromosomal RNP and metachromatic DCR (Stage III) as the disease advanced from early to late stages.\\u000a Nucleolar parachromatin and GCR were not demonstrable while chromosomal RNP was unaltered. Feulgen stain did not reveal any\\u000a significant abnormality. PAS positive substance was deposited

Usha Sharma; S. Saxena; M. L. Sharma

1974-01-01

364

The Predicted G-Protein-Coupled Receptor GPR1 Is Required for Female Sexual Development in the Multicellular Fungus Neurospora crassa  

Microsoft Academic Search

G-protein-coupled receptors (GPCRs) control important aspects of asexual and sexual development in eukaryotic organisms. We have identified a predicted GPCR in the filamentous fungus Neurospora crassa with similarity to cyclic AMP-receptor like GPCRs from Dictyostelium discoideum and GCR1 from Arabidopsis thaliana. Expression of gpr-1 is highest in female reproductive structures, and deletion of gpr-1 leads to defects during sexual development.

Svetlana Krystofova; Katherine A. Borkovich

2006-01-01

365

Waiting times to appearance and dominance of advantageous mutants: estimation based on the likelihood  

Microsoft Academic Search

The germinal center reaction (GCR) of vertebrate immunity provides a remarkable example of evolutionary succession, in which an advantageous phenotype arises as a spontaneous mutation from the parental type and eventually displaces the parental type altogether. In the case of the immune response to the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP), as with several other designed immunogens, the process is dominated by a

Michael D. Radmacher; Thomas B. Kepler

2001-01-01

366

Radiological health risks for exploratory class missions in space.  

PubMed

Crewmembers on missions to the Moon or Mars will be unavoidably exposed to ionizing radiation as they pass through the Van Allen belts and the Galactic Cosmic Ray (GCR) flux. There is the possibility for exposure to proton radiation from Solar Particle Events (SPE). Using absorbed doses and ICRP 26, Linear Energy Transfer (LET) -dependent quality factors, the following dose-equivalents are estimated: In a spacecraft with 0.75 cm aluminum walls (2 g/cm2) at solar minimum, the lunar round trip dose-equivalent is less than 0.05 Sv. During a Mars mission the estimated dose-equivalents are: outbound (Van Allen Belts) <0.02 Sv; Earth to Mars (205 days exposure to free space GCR) 0.32 Sv; 30 days on the Martian surface (GCR) 0.023 Sv; Mars to Earth (225 days exposure to free space) 0.35 Sv; and through the Van Allen Belts 0.02 Sv. Conventionally, the total of 0.73 Sv over 460 days could be expected to increase the risk of cancer mortality in a 35-year old male astronaut by about one percent. However three-fourths of the dose-equivalent in free space is contributed by high LET heavy ions (Z > or = 3) and target fragments with average quality factors of 10.3 and 20 respectively. The biological effectiveness of these radiations is poorly understood; so the quality factors are set at conservatively very high values. The entire concept of absorbed dose/quality factor/dose-equivalent as applied to GCR must be reconsidered. PMID:11537128

Nachtwey, D S; Yang, T C

1991-01-01

367

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

368

Validation of the CATHARE2 code against experimental data from Brayton-cycle plants  

Microsoft Academic Search

In recent years the Commissariat à l’Energie Atomique (CEA) has commissioned a wide range of feasibility studies of future-advanced nuclear reactors, in particular gas-cooled reactors (GCR). The thermohydraulic behaviour of these systems is a key issue for, among other things, the design of the core, the assessment of thermal stresses, and the design of decay heat removal systems. These studies

Fabrice Bentivoglio; Nicolas Tauveron; Geneviève Geffraye; Hervé Gentner

2008-01-01

369

Galactic cosmic ray exposure estimates for SAGE-3 mission in polar orbit  

NASA Astrophysics Data System (ADS)

An analysis of the effects of galactic cosmic ray (GCR) exposures on charge-coupled devices (CCDs) was performed for the SAGE-III 5-year mission in sun-synchronous orbit between 1996 and 2001. A detailed environment model used in conjunction with a geomagnetic vertical cut-off code provides the predicted 5-year fluence of GCR ions. A computerized solid model of the spacecraft was used to define the effective shield thickness distribution around the CCD detector. The particle fluences at the detector location are calculated with the Langley heavy-ion transport code, and these fluences are used in conjunction with estimated nuclear stopping powers to evaluate dosimetric quantities related to the detector degradation. A previous study analyzing effects of trapped particle and solar flare protons indicated an approximate 20 percent reduction in detector sensitivity for the mission. The galactic cosmic ray contribution was thought to be relatively small and therefore was not previously analyzed. The present study provides quantification of the GCR effects, which are found to contribute less than 1 percent of the total environment degradation.

Nealy, John E.; Tipton, Bryan E.

1992-10-01

370

Radiation exposure predictions for short-duration stay Mars missions.  

PubMed

The human radiation environment for several short-duration stay manned Mars missions is predicted using the Mission Radiation Calculation (MIRACAL) program, which was developed at NASA Langley Research Center. This program provides dose estimates for galactic cosmic rays (GCR) and large and ordinary solar proton flare events for various amounts of effective spacecraft shielding (both operational and storm shelter thicknesses) and a given time history of the spacecraft's heliocentric position. The results of this study show that most of the missions can survive the most recent large flares (if they were to occur at the missions' perihelion) if a 25 g/cm2 storm shelter is assumed. The dose predictions show that missions during solar minima (when solar flare activity is the lowest) are not necessarily the minimum dose cases, due to increased GCR contribution during this time period. The direct transfer mission studied has slightly lower doses than the outbound Venus swingby mission [on the order of 10-20 centi-Sieverts (cSv) lower], with the greatest dose differences for the assumed worst case scenario (when the large flares occur at perihelion). The GCR dose for a mission can be reduced by having the crew spend some fraction of its day nominally in the storm shelter (other than during flare events). PMID:11538210

Striepe, S A; Nealy, J E; Simonsen, L C

371

Galactic Cosmic Rays in the Outer Heliosphere  

NASA Astrophysics Data System (ADS)

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 reveal 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. GCR storage times in different regions of the heliosphere: solar wind (red), heliosheath (green) and heliotail (blue) for an observer at 30 AU (left) and at 100 AU (right).

Florinski, V. A.; Washimi, H.; Pogorelov, N. V.; Adams, J. H.; Zank, G. P.

2010-12-01

372

Ternary Nucleation of Sulfuric Acid, Water and Dimethylamine in the Cloud Experiment  

NASA Astrophysics Data System (ADS)

Galactic cosmic ray (GCR) variations were found to correlate with several past climate reconstructions. However, the microphysical mechanism responsible for this link remains mysterious. GCRs are thought to influence the formation of cloud condensation nuclei (CCN): an increased GCR flux could modify cloud properties, and therefore induce a cooling effect on the climate [Kirkby, 2007]. The formation of new particles from the cluster size and their growth to CCN has been investigated at the CLOUD (Cosmics Leaving OUtdoor Droplets) facility at CERN, which consists of a 26 m3 aerosol chamber exposed to an adjustable particle beam, reproducing GCR at different altitudes or latitudes. With state of the art instrumentation for particles of a few nanometers diameter as well as for trace gases, the nucleation of the sulfuric acid (H2SO4) - water (H2O) system, as well as the influence of ammonia (NH3) was already examined in the first experiments [Kirkby et al., 2011]. This paper presents the results on the nucleation of sulfuric acid in the presence of dimethylamine. Kirkby, J. (2007), Cosmic Rays and Climate, Surv Geophys, 28(5-6), 333-375, doi:10.1007/s10712-008-9030-6. Kirkby, J. et al. (2011), Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation, Nature, in press.

Praplan, A. P.; Bianchi, F.; Riccobono, F.; Dommen, J.; Weingartner, E.; Baltensperger, U.; Laboratory Of Atmospheric Chemistry; Cloud Consortium

2011-12-01

373

Cr metal thin film memory  

NASA Astrophysics Data System (ADS)

As state of the art flash memory technologies scale down to sub 30 nm node, conventional floating gate flash memory approaches its physical scaling limit mainly because of the high gate coupling ratio (GCR) requirement to secure proper memory window. Here, we report a novel flash memory device called Cr metal thin film memory (MTFM) that can circumvent the GCR issue and extend flash memory scalability by employing Cr thin film as a storage layer. Cr metal thin film memory devices with simple and low temperature processes produced a wide memory window of 10 V at the +/-18 V voltage sweep with GCR of only 0.3. Such a large window can be adopted for multi-level cell operations, which can further increase the memory density. Also, retention measurement shows more than 10 years retention time due to higher energy barrier between Cr metal and tunnel oxide than conventional poly silicon and tunnel oxide. Cross section transmission electron microscope (TEM) images showed the structure and accurate dimensions of the Cr MTFM device with continuous Cr film and sharp interfaces. As for material characterizations, an amorphous like Cr phase was observed through TEM and x-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) confirmed the Cr-Cr bond and Cr-O bond near the Cr surface after evaporation and rapid thermal annealing. This metal thin film memory may open a new route to achieve the terabit level flash memory.

Hong, Augustin J.; Kim, Jiyoung; Kim, Kyoungwhan; Wang, Yong; Xiu, Faxian; Jeon, Jaeseok; Park, Jemin; Rauda, Iris; Chen, Li-Min; Yang, Yang; Tolbert, Sarah; Zou, Jin; Wang, Kang L.

2011-09-01

374

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

375

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

PubMed

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. PMID:7480628

Cucinotta, F A; Wilson, J W

1995-08-01

376

Galactic-cosmic-ray-produced 3He in a ferromanganese crust: any supernova 60Fe excess on earth?  

PubMed

An excess of 60Fe in 2.4-3.2 x 10(6) year old ferromanganese crust (237 KD) from the deep Pacific Ocean has been considered as evidence for the delivery of debris from a nearby supernova explosion to Earth. Extremely high ;{3}He/;{4}He (up to 6.12 x 10(-3)) and 3He concentrations (up to 8 x 10(9) atoms/g) measured in 237 KD cannot be supernova-derived. The helium is produced by galactic cosmic rays (GCR) and delivered in micrometeorites that have survived atmospheric entry to be trapped by the crust. 60Fe is produced by GCR reactions on Ni in extraterrestrial material. The maximum (3)He/(60)Fe of 237 KD (80-850) is comparable to the GCR (3)He/(60)Fe production ratio (400-500) predicted for Ni-bearing minerals in iron meteorites. The excess 60Fe can be plausibly explained by the presence of micrometeorites trapped by the crust, rather than injection from a supernova source. PMID:17501264

Basu, S; Stuart, F M; Schnabel, C; Klemm, V

2007-04-02

377

Modulation of Galactic cosmic rays during the unusual solar minimum of cycle 24  

NASA Astrophysics Data System (ADS)

Intensity of Galactic cosmic rays (GCR) measured during the recent solar minimum was the highest ever recorded since space age, while the magnitude of solar and interplanetary magnetic field and the speed of the solar wind in heliosphere was very low, but the tilt of heliospheric current sheet was not at the lowest level. This indicates that the modulation of cosmic ray is not dominated by the mechanism of particle drift through the current sheet during this A<0 cycle as we normally think. Possible reasons for the record cosmic ray flux include increase of particle diffusion and regular drift due to the weaker magnetic field, reduction of particle energy loss due to the slower solar wind speed, or closer termination shock radial distance due to smaller solar wind pressure. In this paper, We use a model of GCR transport in the three-dimensional heliosphere based on a simulation of Markov stochastic process to study the effect of these parameters. We will show which is the proper reason for the abnormally high observed GCR flux. Implication or relationship of this study to the understanding of the modulation of cosmic rays during historical deep solar minima will be discussed.

Lingling, Z.; Qin, G.; Zhang, M.

2010-12-01

378

The First Cosmic Ray Albedo Proton Map of the Moon  

NASA Astrophysics Data System (ADS)

The Lunar Reconnaissance Orbiter (LRO) has been observing the surface and environment of the Moon since June of 2009. The CRaTER instrument (Cosmic Ray Telescope for the Effects of Radiation) on LRO is designed to characterize the lunar radiation environment and its effects on simulated human tissue. CRaTER's multiple solid state detectors can be used to discriminate the different elements in the galactic cosmic ray (GCR) population above ~10 MeV/nucleon, and can also distinguish between primary GCR protons arriving from deep space and secondary albedo particles ejected from the lunar surface. We use protons coming up from the lunar surface with energies greater than 60 MeV to construct an albedo proton map of the Moon. The map accounts for variations in the secondary particles driven by fluctuations in the primary GCR population, and thus reveals any true spatial variations in the proton spallation yield related to elemental abundances in the regolith. Presently we find no significant differences in the yields from different regions on the Moon, although the anticipated collection of more data will improve the proton counting statistics. The average global proton yield has been increasing for the past several months, consistent with the reduction in lower-energy GCRs that is expected when solar activity increases.

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

2011-12-01

379

A computational model for an open-cycle gas core nuclear rocket  

SciTech Connect

A computational model of an open-cycle gas core nuclear rocket (GCR) is developed. The solution is divided into two distinct areas--thermal hydraulics and neutronics. To obtain the thermal-hydraulic solution, a computer code is written that solves the Navier-Stokes, energy, and species diffusion equations. The two-dimensional transport code TWODANT is used to obtain the neutronics solution. The thermal-hydraulic and neutronic models are coupled, and the solution proceeds in an iterative manner until a consistent power density profile is obtained. Various open-cycle GCR designs are evaluated. First, it is assumed that the fuel and propellant do not mix. In this ideal case, it is found that the limiting factor in determining thrust and specific impulse is the maximum allowable wall heat flux. Following this simplified study, the results from a complete thermal-hydraulic/neutronic solution are presented, and the use of alternate fuels and propellants is considered. Next, a parametric design study is conducted that examine the rocket performance of the open-cycle GCR as a function of various design and operational parameters. It is found that fuel containment is very adversely affected by high reactor power or rocket acceleration. Finally, some concepts are discussed that could help improve fuel containment.

Poston, D.I. [Los Alamos National Lab., NM (United States). Nuclear Systems Design and Analysis Group; Kammash, T. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering

1996-01-01

380

Optimizing Reduction in Basal Hyperglucagonaemia to Repair Defective Glucagon Counterregulation in Insulin Deficiency  

PubMed Central

In health, the pancreatic islet cells work as a network with highly coordinated signals over time to balance glycaemia within a narrow range. In type 1 diabetes (T1DM), with autoimmune destruction of the ?-cells, lack of insulin is considered the primary abnormality and is the primary therapy target. However, replacing insulin alone does not achieve adequate glucose control and recent studies have focused on controlling the endogenous glucagon release as well. In T1DM, glucagon secretion is disordered but not absolutely deficient; it may be excessive postprandially yet it is characteristically insufficient and delayed in response to hypoglycaemia. We review our system-level analysis of the pancreatic endocrine network mechanisms of glucagon counterregulation (GCR) and their dysregulation in T1DM and focus on possible use of ?-cell inhibitors (ACI) to manipulate the glucagon axis to repair the defective GCR. Our results indicate that the GCR abnormalities are of “network origin”. The lack of ?-cell signalling is the primary deficiency which contributes to two separate network abnormalities: (i) absence of a ?-cell switch-off trigger and (ii) increase intraislet basal glucagon. A strategy to repair these abnormalities with ACI is proposed which could achieve better control of glycaemia with reduced hypoglycaemia risk.

Farhy, Leon S.; McCall, Anthony L.

2012-01-01

381

Assessing access of galactic cosmic rays at Moon's orbit  

NASA Astrophysics Data System (ADS)

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 magnetic field of its own. However, as it orbits Earth, the Moon traverses not only the weak interplanetary magnetic field but also the distant magnetic tail of Earth's magnetosphere. We combine an empirical magnetic field model of Earth's magnetosphere with a fully-relativistic charged particle trajectory code to model and assess the access of GCR at the Moon's orbit. We follow protons with energies of 1, 10 and 100 MeV starting from an isotropic distribution at large distances outside a volume of space including Earth's magnetosphere and the lunar orbit. The simulation result shows that Earth's magnetosphere does not measurably modify protons of energy greater than 1 MeV at distances outside the geomagnetic cutoff imposed by Earth's strong dipole field very near to the planet. Therefore, in contrast to Winglee and Harnett (2007), we conclude that Earth's magnetosphere does not provide any substantial magnetic shielding at the Moon's orbit. These simulation results will be compared to LRO/CRaTER data after its planned launch in June 2009.

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

2009-05-01

382

[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

383

Galactic Cosmic Ray Intensity Response to Interplanetary Coronal Mass Ejections/Magnetic Clouds in 1995 - 2009  

NASA Astrophysics Data System (ADS)

We summarize the response of the galactic cosmic ray (CGR) intensity to the passage of the more than 300 interplanetary coronal mass ejections (ICMEs) and their associated shocks that passed the Earth during 1995 - 2009, a period that encompasses the whole of Solar Cycle 23. In ˜ 80% of cases, the GCR intensity decreased during the passage of these structures, i.e., a "Forbush decrease" occurred, while in ˜ 10% there was no significant change. In the remaining cases, the GCR intensity increased. Where there was an intensity decrease, minimum intensity was observed inside the ICME in ˜ 90% of these events. The observations confirm the role of both post-shock regions and ICMEs in the generation of these decreases, consistent with many previous studies, but contrary to the conclusion of Reames, Kahler, and Tylka ( Astrophys. J. Lett. 700, L199, 2009) who, from examining a subset of ICMEs with flux-rope-like magnetic fields (magnetic clouds) argued that these are "open structures" that allow free access of particles including GCRs to their interior. In fact, we find that magnetic clouds are more likely to participate in the deepest GCR decreases than ICMEs that are not magnetic clouds.

Richardson, I. G.; Cane, H. V.

2011-06-01

384

First Cosmic Ray Proton Albedo Map of the Moon  

NASA Astrophysics Data System (ADS)

The Lunar Reconnaissance Orbiter (LRO) has been observing the surface and environment of the Moon since June of 2009. The CRaTER instrument (Cosmic Ray Telescope for the Effects of Radiation) on LRO is designed to characterize the lunar radiation environment and its effects on simulated human tissue. CRaTER's multiple solid-state detectors can be used to discriminate the different elements in the galactic cosmic ray (GCR) population above ~10 MeV/nucleon, and can also distinguish between primary GCR protons arriving from deep space from some secondary particles backscattered from the lunar surface (i.e., "albedo"). We use the previously reported strong presence of > 10 MeV protons coming up from the lunar surface to construct a proton albedo map of the Moon. The map accounts for time variation in the secondary particles driven by time variations in the primary GCR population, thus revealing any true spatial variation of the proton albedo with lunar surface properties such as gross mineralogical abundance differences between regolith in maria and highlands.

Wilson, J. K.; Spence, H.; Kasper, J.; Golightly, M.; Blake, J.; Mazur, J. E.; Townsend, L.; Case, A.; Looper, M. D.

2010-12-01

385

Energetic Particles Near and at the Heliopause  

NASA Astrophysics Data System (ADS)

After the Voyagers' crossing of the heliospheric termination shock, there has been great anticipation of the next crossing -- that of the heliopause, which is the boundary between plasma of solar origin and the ambient interstellar plasma. Recent Voyager 1 observations suggest that the spacecraft is approaching the heliopause. Here, I will discuss possible effects of this boundary on energetic particles . The observed galactic cosmic rays (GCR) originate in the galaxy and must cross the heliopause from the outside, whereas the anomalous cosmic rays (ACR) are most probably accelerated near or inside of the heliopause (termination shock, heliosheath or the heliopause itself). One important question involves the effects of the interstellar medium, beyond the heliopause, on the energetic particles. In most models of the solar modulation of GCR, the heliopause is taken to be where the GCR intensity becomes equal to the undisturbed interstellar GCR intensity. This assumption is difficult to justify, and may in fact be significantly incorrect. Because of uncertainties regarding the local interstellar medium, a number of possibilities regarding this question are compatible with present knowledge. Similarly, models of the ACR generally set a free-escape boundary (zero intensity) at the heliopause . Again, as with galactic cosmic rays, a number of other possibilities are consistent with our present knowledge. ACR escape may be impeded. Energetic particles may be accelerated at the heliopause. It has been proposed that acceleration in reconnections compressions become strong near the heliopause and produce the ACR there. Furthermore, it is possible that fluid velocity shear, which also accelerates energetic charged particles, is strong at the heliopause. It has also been proposed that the energetic-particle transport coefficients are considerably modified in the outer heliosphere, either because the warps of the heliospheric current sheet are brought very close together to less than the gyro-radius of the GCR or ACR, or because reconnection events caused by the warps in the current sheet produce characteristic magnetic structures. Finally, instabilities of various kinds at the heliopause have been proposed and these may result in particle acceleration or changes in transport. The various possibilities will be discussed and compared with available observations. New tests will be discussed.

Jokipii, J. R.

2011-12-01

386

Usefulness of Peripheral Blood Mononuclear Cells to Predict Clinical Response to Corticosteroids in Asthmatics  

PubMed Central

Background Blood tests are needed to identify steroid resistant (SR) asthmatics early so they can be managed with alternative anti-inflammatory therapy. Objective to assess usefulness of peripheral blood to predict steroid response in asthmatics. Methods 19 asthmatics with FEV1<80% predicted were classified as SR or steroid sensitive (SS) based on change in lung FEV1% following 7 days of oral prednisone. Blood was collected at baseline and 30 days post-prednisone administration (Visit 3). PBMC were cultured for 4h+/?10?7 M dexamethasone (DEX), and cellular response to DEX was determined by real-time PCR based on expression analysis of steroid-regulated genes. Suppression of PHA-induced T cell proliferation by DEX was assessed. Results Prednisone significantly improved FEV1% in SS (mean±SE: 17.5±2.4%) but not SR asthmatics (0.8±2.0%) (p<0.001). Prior to prednisone treatment, MKP-1 (p=0.01) and IL-8 mRNA (p<0.05) levels were significantly higher in PBMC from SR asthmatics. TNF-alpha (p<0.05) and IL-8 fold suppression by DEX (p<0.05) were significantly reduced in SR asthmatics PBMC. The expression of GCR-beta, but not GCR-alpha was significantly elevated in PBMC of SR asthmatics (p=0.01). DEX IC50 for PBMC proliferation was significantly higher for SR asthmatics (p<0.05). These markers no longer differed between groups in PBMC 30 days post-prednisone administration. The composite score of assays at baseline, prior to prednisone, was significantly different between SR and SS asthmatics (p<0.001). Conclusions PBMC from SR asthmatics have higher baseline MKP-1, IL-8, and GCR-beta mRNA levels, a lower GCR-alpha/GCR-beta mRNA ratio, are less responsive to suppression of TNF-alpha and IL-8 by DEX, and require more DEX to suppress T cell proliferation as compared to SS asthmatics.

Goleva, Elena; Jackson, Leisa P.; Gleason, Melanie; Leung, Donald Y.M.

2012-01-01

387

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

SciTech Connect

Any reactor that utilizes fuel consisting of a fissile material in a gaseous state may be referred to as a gaseous core reactor (GCR). Studies on GCRs have primarily been limited to the conceptual phase, mostly due to budget cuts and program cancellations in the early 1970's. A few scientific experiments have been conducted on candidate concepts, primarily of static pressure fissile gas filling a cylindrical or spherical cavity surrounded by a moderating shell, such as beryllium, heavy water, or graphite. The main interest in this area of nuclear power generation is for space applications. The interest in space applications has developed due to the promise of significant enhancement in fuel utilization, safety, plant efficiency, special high-performance features, load-following capabilities, power conversion optimization, and other key aspects of nuclear power generation. The design of a successful GCR adapted for use in space is complicated. The fissile material studied in the pa st has been in a fluorine compound, either a tetrafluoride or a hexafluoride. Both of these molecules have an impact on the structural material used in the making of a GCR. Uranium hexafluoride as a fuel allows for a lower operating temperature, but at temperatures greater than 900K becomes essentially impossible to contain. This difficulty with the use of UF6 has caused engineers and scientists to use uranium tetrafluoride, which is a more stable molecule but has the disadvantage of requiring significantly higher operating temperatures. Gas core reactors have traditionally been studied in a steady state configuration. In this manner a fissile gas and working fluid are introduced into the core, called a cavity, that is surrounded by a reflector constructed of materials such as Be or BeO. These reactors have often been described as cavity reactors because the density of the fissile gas is low and criticality is achieved only by means of the reflector to reduce neutron leakage from the core. Still there are problems of containment since many of the proposed vessel materials such as W or Mo have high neutron cross sections making the design of a critical system difficult. There is also the possibility for a GCR to remain in a subcritical state, and by the use of a shockwave mechanism, increase the pressure and temperature inside the core to achieve criticality. This type of GCR is referred to as a shockwave-driven pulsed gas core reactor. These two basic designs were evaluated as advance concepts for space power and propulsion.

Samim Anghaie

2002-08-13

388

The Event Tunnel: Interactive Visualization of Complex Event Streams for Business Process Pattern Analysis  

Microsoft Academic Search

Event-based systems are gaining increasing popularity for building loosely coupled and distributed systems. Since business processes are becoming more interconnected and event-driven, event-based systems fit well for supporting and monitoring business processes. In this paper, we present an event-based business intelligence tool, the Event Tunnel framework. It provides an interactive visualiza- tion of event streams to support business analysts in

Martin Suntinger; Hannes Obweger; Josef Schiefer; M. Eduard Gröller

2008-01-01

389

Coupled W-Os-Pt isotope systematics in IVB iron meteorites: In situ neutron dosimetry for W isotope chronology  

NASA Astrophysics Data System (ADS)

Tungsten isotope compositions of magmatic iron meteorites yield ages of differentiation that are within ±2 Ma of the formation of CAIs, with the exception of IVB irons that plot to systematically less radiogenic compositions yielding erroneously old ages. Secondary neutron capture due to galactic cosmic ray (GCR) irradiation is known to lower the ?182W of iron meteorites, adequate correction of which requires a measure of neutron dosage which has not been available, thus far. The W, Os and Pt isotope systematics of 12 of the 13 known IVB iron meteorites were determined by MC-ICP-MS (W, Os, Pt) and TIMS (Os). On the same dissolutions that yield precise ?182W, stable Os and Pt isotopes were determined as in situ neutron dosimeters for empirical correction of the ubiquitous cosmic-ray induced burn-out of 182W in iron meteorites. The W isotope data reveal a main cluster with ?182W of ˜-3.6, but a much larger range than observed in previous studies including irons (Weaver Mountains and Warburton Range) that show essentially no cosmogenic effect on their ?182W. The IVB data exhibits resolvable negative anomalies in ?189Os (-0.6?) and complementary ?190Os anomalies (+0.4?) in Tlacotepec due to neutron capture on 189Os which has approximately the same neutron capture cross section as 182W, and captures neutrons to produce 190Os. The least irradiated IVB iron, Warburton Range, has ?189Os and ?190Os identical to terrestrial values. Similarly, Pt isotopes, which are presented as ?192Pt, ?194Pt and ?196Pt range from +4.4? to +53?, +1.54? to -0.32? and +0.73? to -0.20?, respectively, also identify Tlacotepec and Dumont as the most GCR-damaged samples. In W-Os and W-Pt isotope space, the correlated isotope data back-project toward a 0-epsilon value of ?192Pt, ?189Os and ?190Os from which a pre-GCR irradiation ?182W of -3.42±0.09 (2?) is derived. This pre-GCR irradiation ?182W is within uncertainty of the currently accepted CAI initial ?182W. The Pt and Os isotope correlations in the IVB irons are in good agreement with a nuclear model for spherical irons undergoing GCR spallation, although this model over-predicts the change of ?182W by ˜2×, indicating a need for better W neutron capture cross section determinations. A nucleosynthetic effect in ?184W in these irons of -0.14±0.08 is confirmed, consistent with the presence of Mo and Ru isotope anomalies in IVB irons. The lack of a non-GCR Os isotope anomaly in these irons requires more complex explanations for the production of W, Ru and Mo anomalies than nebular heterogeneity in the distribution of s-process to r-process nuclides.

Wittig, N.; Humayun, M.; Brandon, A. D.; Huang, S.; Leya, I.

2013-01-01

390

Distribution And Nature Of The Accretion-powered Binaries In The Galactic Center Region From The Chandra BLS  

NASA Astrophysics Data System (ADS)

We have completed the analysis of the Chandra Bulge Latitude Survey (BLS), a close-tiled mosaic of 36 ACIS-I fields obtained with Chandra in cycles 7 - 9 and covering (l, b) +/-0.3, +/-1.4deg. With 15ksec exposures per field, some 2500 sources are detected, with luminosities Lx(0.3-8keV) > 10^32 erg/s. This survey maps the latitude distribution of the galactic center region (GCR) sources for comparison with the longitude distribution of the Wang et al (2002) survey. The BLS extends below the plane to (just) include the "Limiting Window" field (b = -1.3deg, the closest low extinction window to SgrA* with Av 4) we originally observed in a 100ksec pointing and which was recently observed in a much deeper pointing by Revnivtsev et al to study the Galactic Ridge. From our optical (VRI; CTIO-4m/Mosaic) and nIR (JHK; CTIO-4m/ISPI) images, we identify foreground sources and constrain the Bulge sources to not be wind-fed high mass systems. By selecting on sources detected in the Hard (>2keV) but not in the Soft (<2keV) bands, we can reject foreground sources and measure the latitude and projected radial distributions of the hard sources in the GCR that are likely dominated by accreting white dwarfs (CVs) but also include quiescent low mass X-ray binaries (qLMXBs). And from comparison with the Wang survey, the combined radial distribution of Lx 10^32-33 erg/s hard sources in the GCR, which are dominated by accreting compact objects in binaries, is derived for comparison with models of the Bulge and its formation history.

Grindlay, Jonathan E.; Hong, J.; Servillat, M.; Zhao, P.; Allen, B.; van den Berg, M.

2011-05-01

391

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

392

Oscillations of galactic cosmic rays and solar indices before the arrival of relativistic solar protons  

NASA Astrophysics Data System (ADS)

Using modern wavelet analysis techniques, we have made an attempt to search for oscillations of intensity of galactic cosmic rays (GCR), sunspot numbers (SS) and magnitudes of coronal index (CI) implying that the time evolution of those oscillations may serve as a precursor of Ground Level Enhancements (GLEs) of solar cosmic rays (SCR). From total number of 70 GLEs registered in 1942-2006, the four large events — 23 February 1956, 14 July 2000, 28 October 2003, and 20 January 2005 — have been chosen for our study. By the results of our analysis, it was shown that a frequency of oscillations of GCR decreases as time approaches to the event day. We have also studied a behaviour of common periodicities of GCR and SCR within the time interval of individual GLE. The oscillations of GLE occurrence rate (OR) at different stages of the solar activity (SA) cycle is of special interest. We have found some common periodicities of SS and CI in the range of short (2.8, 5.2, 27 and 60 days), medium (0.3, 0.5, 0.7, 1.3, 1.8 and 3.2 years) and long (4.6 and 11.0 years) periods. Short and medium periodicities, in general, are rather concentrated around the maxima of solar cycles and display the complex phase relations. When comparing these results with the behaviour of OR oscillations we found that the period of 11 years is dominating (controlling); it is continuous over the entire time interval of 1942-2006, and during all this time it displays high synchronization and clear linear ratios between the phases of oscillations of ?, SS and CI. It implies that SCR generation is not isolated stochastic phenomena characteristic exclusively for chromospheric and/or coronal structures. In fact, this process may have global features and involve large regions in the Sun's atmosphere.

Miroshnichenko, L. I.; Pérez-Peraza, J. A.; Velasco-Herrera, V. M.; Zapotitla, J.; Vashenyuk, E. V.

2012-09-01

393

Probabilistic assessment of radiation risk for astronauts in space missions  

NASA Astrophysics Data System (ADS)

Accurate estimations of the health risks to astronauts due to space radiation exposure are necessary for future lunar and Mars missions. Space radiation consists of solar particle events (SPEs), comprised largely of medium energy protons (less than several hundred MeV); and galactic cosmic rays (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. A solar modulation model has been developed for the temporal characterization of the GCR environment, which is represented by the deceleration potential, ?. The risk of radiation exposure to astronauts as well as to hardware from SPEs during extra-vehicular activities (EVAs) or in lightly shielded vehicles is a major concern for radiation protection. To support the probabilistic risk assessment for EVAs, which could be up to 15% of crew time on lunar missions, we estimated the probability of SPE occurrence as a function of solar cycle phase using a non-homogeneous Poisson model [1] to fit the historical database of measurements of protons with energy>30 MeV, ?30. The resultant organ doses and dose equivalents, as well as effective whole body doses, for acute and cancer risk estimations are analyzed for a conceptual habitat module and for a lunar rover during space missions of defined durations. This probabilistic approach to radiation risk assessment from SPE and GCR is in support of mission design and operational planning for future manned space exploration missions. Internal documentation of NASA Constellation Trade Study (F.A. Cucinotta, personal communication).

Kim, Myung-Hee Y.; De Angelis, Giovanni; Cucinotta, Francis A.

2011-04-01

394

Mars Odyssey measurements of galactic cosmic rays and solar particles in Mars orbit, 2002-2008  

NASA Astrophysics Data System (ADS)

The instrument payload aboard the 2001 Mars Odyssey orbiter includes several instruments that are sensitive to energetic charged particles from the galactic cosmic rays (GCR) and solar particle events (SPE). The Martian Radiation Environment Experiment (MARIE) was a dedicated energetic charged particle spectrometer, but it ceased functioning during the large solar storm of October/November 2003. Data from two other Odyssey instruments are used here: the Gamma Ray Spectrometer and the scintillator component of the High Energy Neutron Detector. Though not primarily designed to measure energetic charged particles, both systems are sensitive to them, and several years of data are available from both. Using the MARIE data for calibration of the other systems, count rates can be normalized (with significant uncertainties) to absolute fluxes of both GCR and solar energetic particles (SEP). The data, which cover the time span from early 2002 through the end of 2007, clearly show the solar cycle-dependent modulation of the GCR starting in 2004. Many SPEs were recorded as well and are cataloged here. Threshold energies were relatively high, ranging from 16 MeV in the most sensitive channel to 42 MeV. These thresholds are not optimal for detailed studies of SEPs, but this is the range of interest for calculations of dose and dose equivalent, pertinent to human flight, and covering that range was the original motivation for MARIE. The data are available on request and are potentially of use for the Earth-Moon-Mars Radiation Environment Module collaboration and other heliospheric modeling projects.

Zeitlin, C.; Boynton, W.; Mitrofanov, I.; Hassler, D.; Atwell, W.; Cleghorn, T. F.; Cucinotta, F. A.; Dayeh, M.; Desai, M.; Guetersloh, S. B.; Kozarev, K.; Lee, K. T.; Pinsky, L.; Saganti, P.; Schwadron, N. A.; Turner, R.

2010-11-01

395

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

396

High Energy Utilization, Co-Generation Nuclear power Plants With Static Energy Conversion  

SciTech Connect

In addition to being cost effective, very small nuclear power plants with static energy conversion could meet the needs and the energy mix in underdeveloped countries and remote communities, which may include electricity, residential and industrial space heating, seawater desalination, and/or high temperature process heat or steam for industrial uses. These plants are also an attractive option in naval, marine, and undersea applications, when the absence of a sound signature is highly desirable. An Analysis is performed of Gas Cooled Reactor (CGR) and Liquid Metal Cooled Reactor (LMR), very small nuclear power plants with static energy conversion, using a combination of options. These include Alkali Metal Thermal-to-Electric Converters (AMTECs) and both single segment and segmented thermoelectric converters. The total energy utilization of these plants exceeds 88%. It includes the fraction of the reactor's thermal power converted into electricity and delivered to the Grid at 6.6 kVA and those used for residential and industrial space heating at {approx}370 K, seawater desalination at 400 K, and/or high temperature process heat or steam at {approx}850 K. In addition to its inherently high reliability, modularity, low maintenance and redundancy, static energy conversion used in the present study could deliver electricity to the Grid at a net efficiency of 29.5%. A LMR plant delivers 2-3 times the fraction of the reactor thermal power converted into electricity in a GCR plant, but could not provide for both seawater desalination and high temperature process heat/steam concurrently, which is possible in GCR plants. The fraction of the reactor's thermal power used for non-electrical power generation in a GCR plant is {approx} 10 - 15% higher than in a LMR plant. (authors)

El-Genk, Mohamed S.; Tournier, Jean-Michel P. [Institute for Space and Nuclear Power Studies and Chemical and Nuclear Engineering Department, The University of New Mexico, Albuquerque, NM (United States)

2002-07-01

397

Probabilistic Assessment of Cancer Risk from Solar Particle Events  

NASA Astrophysics Data System (ADS)

For long duration missions outside of the protection of the Earth's magnetic field, space radi-ation 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 es-timated 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 5th 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 po-tential (?). 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.

398

Lightning-driven inner radiation belt energy deposition into the atmosphere: implications for ionisation-levels and neutral chemistry  

NASA Astrophysics Data System (ADS)

Lightning-generated whistlers lead to coupling between the troposphere, the Van Allen radiation belts and the lower-ionosphere through Whistler-induced electron precipitation (WEP). Lightning produced whistlers interact with cyclotron resonant radiation belt electrons, leading to pitch-angle scattering into the bounce loss cone and precipitation into the atmosphere. Here we consider the relative significance of WEP to the lower ionosphere and atmosphere by contrasting WEP produced ionisation rate changes with those from Galactic Cosmic Radiation (GCR) and solar photoionisation. During the day, WEP is never a significant source of ionisation in the lower ionosphere for any location or altitude. At nighttime, GCR is more significant than WEP at altitudes <68 km for all locations, above which WEP starts to dominate in North America and Central Europe. Between 75 and 80 km altitude WEP becomes more significant than GCR for the majority of spatial locations at which WEP deposits energy. The size of the regions in which WEP is the most important nighttime ionisation source peaks at ~80 km, depending on the relative contributions of WEP and nighttime solar Lyman-?. We also used the Sodankylä Ion Chemistry (SIC) model to consider the atmospheric consequences of WEP, focusing on a case-study period. Previous studies have also shown that energetic particle precipitation can lead to large-scale changes in the chemical makeup of the neutral atmosphere by enhancing minor chemical species that play a key role in the ozone balance of the middle atmosphere. However, SIC modelling indicates that the neutral atmospheric changes driven by WEP are insignificant due to the short timescale of the WEP bursts. Overall we find that WEP is a significant energy input into some parts of the lower ionosphere, depending on the latitude/longitude and altitude, but does not play a significant role in the neutral chemistry of the mesosphere.

Rodger, C. J.; Enell, C.-F.; Turunen, E.; Clilverd, M. A.; Thomson, N. R.; Verronen, P. T.

2007-08-01

399

Neutron density profile in the lunar subsurface produced by galactic cosmic rays  

NASA Astrophysics Data System (ADS)

Neutron production by galactic cosmic rays (GCR) in the lunar subsurface is very important when performing lunar and planetary nuclear spectroscopy and space dosimetry. Further im-provements to estimate the production with increased accuracy is therefore required. GCR, which is a main contributor to the neutron production in the lunar subsurface, consists of not only protons but also of heavy components such as He, C, N, O, and Fe. Because of that, it is important to precisely estimate the neutron production from such components for the lunar spectroscopy and space dosimetry. Therefore, the neutron production from GCR particles in-cluding heavy components in the lunar subsurface was simulated with the Particle and Heavy ion Transport code System (PHITS), using several heavy ion interaction models. This work presents PHITS simulations of the neutron density as a function of depth (neutron density profile) in the lunar subsurface and the results are compared with experimental data obtained by Apollo 17 Lunar Neutron Probe Experiment (LNPE). From our previous study, it has been found that the accuracy of the proton-induced neutron production models is the most influen-tial factor when performing precise calculations of neutron production in the lunar subsurface. Therefore, a benchmarking of proton-induced neutron production models against experimental data was performed to estimate and improve the precision of the calculations. It was found that the calculated neutron production using the best model of Cugnon Old (E < 3 GeV) and JAM (E > 3 GeV) gave up to 30% higher values than experimental results. Therefore, a high energy nuclear data file (JENDL-HE) was used instead of the Cugnon Old model at the energies below 3 GeV. Then, the calculated neutron density profile successfully reproduced the experimental data from LNPE within experimental errors of 15% (measurement) + 30% (systematic). In this presentation, we summarize and discuss our calculated results of neutron production in the lunar subsurface.

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

400

Interstellar environment change: effects on heliospheric structure, galactic cosmic ray modulation and cosmogenic isotope production.  

NASA Astrophysics Data System (ADS)

Galactic cosmic ray (GCR) intensity levels in the inner heliosphere over the past million years, preserved in cosmogenic isotope records, display significant variability on virtually all timescales. Here we focus on the variability caused by changes in the interstellar environment of the Sun as it encounters interstellar clouds or low-density regions (supernova bubbles) during its journey through the Galaxy. Three possible environments are compared and the resulting structure of the heliosphere investigated: the tenuous fully ionized Local Bubble, the Local Interstellar Cloud, and a dense cold cloud of pure atomic hydrogen. Using several plausible models of interplanetary turbulence evolution and particle diffusion we investigate the dependence of the cosmic-ray mean free paths and intensities on the size of the modulation region and the pickup ion (PUI) intensities. We show that, while denser clouds usually yield smaller diffusion coefficients due to enhanced PUI turbulence, GCR radiation levels in the inner heliosphere are actually increased due to a reduction in the size of the modulation region. Our results indicate that GCR intensities at Earth can vary by a factor 2 to 7 between 300 MeV and 1 GeV compared to the present intensity. Interestingly, most of the changes are due to a variation in the thickness of the modulation wall in the inner heliosheath. Finally, we calculate cosmogenic isotope production rates in the Earth's atmosphere for the three environments and show that Beryllium-10 concentration could vary between 25% declines in low-density environments to increases in excess of 300% in high density interstellar clouds.

Mueller, H. R.; Florinski, V.; Zank, G. P.

2005-12-01

401

Modeling the Relationship Between Neutron Counting Rates and Sunspot Numbers Using the Hysteresis Effect  

NASA Astrophysics Data System (ADS)

Several studies show that temporal variations in the Galactic cosmic ray (GCR) intensity display a distinct 11-year periodicity due to solar modulation of the galactic cosmic rays in the heliosphere. The 11-year periodicity of GCRs is inversely proportional to, but out of phase with, the 11-year solar cycle, implying that there is a time lag between actual solar cycle and the GCR intensity, which is known as the hysteresis effect. In this study, we use the hysteresis effect to model the relationship between neutron counting rates (NCRs), an indicator of the GCR intensity, and sunspot numbers (SSNs) over the period that covers the last four solar cycles (20, 21, 22, and 23). Both linear and ellipse models were applied to SSNs during odd and even cycles in order to calculate temporal variations of NCRs. We find that ellipse modeling provides higher correlation coefficients for odd cycles compared to linear models, e.g. 0.97, 0.97, 0.92, and 0.97 compared to 0.69, 0.72, 0.53, and 0.68 for data from McMurdo, Swarthmore, South Pole, and Thule neutron monitors, respectively, during solar cycle 21 with overall improvement of 31 % for odd cycles. When combined to a continuous model, the better correlation observed for the odd cycles increases the overall correlation between observed and modeled NCRs. The new empirical model therefore provides a better representation of the relationship between NCRs and SSNs. A major goal of the ongoing research is to use the new non-linear empirical model to reconstruct SSNs on annual time scales prior to 1610, where we do not have observational records of SSNs, based on changes in NCRs reconstructed from 10Be in ice cores.

Inceoglu, F.; Knudsen, M. F.; Karoff, C.; Olsen, J.

2013-09-01

402

Summarizing ChaMPlane: Global Distributions And Nature Of Faint Chandra XRBs in the Galaxy  

NASA Astrophysics Data System (ADS)

We summarize the global properties of sources detected in our nearly 10y ChaMPlane survey of faint (<0.01 cts/s) Chandra sources in the Galactic plane. In this presentation, we focus on sources detected above 2 keV which are dominated by CVs and XRBs. Using the GCR hard sources with optical counterparts (Zhao et al), we derive constraints on luminosity and spatial distributions for sources out to 3 kpc (for NH < 3 E21) for comparison with all ChaMPlane fields with similar limiting NH to constrain the global distributions of CVs and qLMXBs in the Galaxy.

Grindlay, Jonathan E.; Hong, J.; van den Berg, M.; Servillat, M.; Zhao, P.; Allen, B.

2011-09-01

403

A Strong Constraint on The Anomalous-Cosmic-Ray Source Location  

NASA Astrophysics Data System (ADS)

The source location of the anomalous cosmic rays (ACR) remains an item of debate. Energetic-particle observations from the Voyagers near and beyond the heliospheric termination shock showed that the expectations of the generally accepted, simple, models of acceleration of the ACR at the termination shock were not met. Instead, the intensities of the lowest-energy particles observed by LECP increased right at the shock, as expected whereas, at higher energies, the increase was gradual. This anomaly led to the proposal of number of alternate mechanisms, where the acceleration did not occur at the shock, but instead was due to either compressions or reconnection in the heliosheath. These alternate mechanisms have the acceleration occuring in the distant heliosheath, near the heliopause. In this talk, we point out that observations from Voyager 1 made nearly 20 years ago, when it was at some 46 AU from the Sun, well-inside of the termination shock, provide an important constraint on the distance to the source of the ACR (McDonald, et al, 2000). These authors compared the recovery of both ACR and galactic cosmic rays (GCR) from a sudden decrease caused by a merged interaction region crossing the spacecraft. The recovery of the GCR takes much longer than that of the ACR. McDonald etal used the observations to locate the source of the ACR (which at that time they identified with the termination shock) at 88.5 +/- 7 AU from the Sun. The modulation boundary for GCR was much further out. Subsequently, Kota and Jokipii (2001) modeled the effects of a GMIR, using a propagating disturbance and acceleration of the ACR by the termination shock at 90 AU. This showed good agreement with the observations. Interpreted in the light of present issues, these analyses provide a significant constraint on the radius of the source of cosmic rays, regardless of the acceleration mechanism. If the boundary of GCR modulation is at some 130 AU or further out (possibly the heliopause), then the source of ACR is significantly closer. Given the McDonald, etal estimate of 88.5 AU, the location of this source is consistent with the source being the termination shock, but not near the heliopause. Reference McDonald, F. B. etal, JGR, 105,1, 2000. Reference Jokipii, J. R. and Kota, J., Proceedings of ICRC, Hamburg, 2001.

Jokipii, J. R.; Kota, J.

2011-12-01

404

Maternal undernutrition programs offspring adrenal expression of steroidogenic enzymes.  

PubMed

The aim of this study was to determine the influence of maternal undernutrition (MUN) on maternal and offspring adrenal steroidogenic enzymes. Pregnant Sprague-Dawley rats were 50% food-restricted from day 10 of gestation until delivery. Control animals received ad libitum food. Offspring were killed on day 1 of life (P1) and at 9 months. We determined the messenger RNA (mRNA) expression of steroidogenic enzymes by real-time reverse transcriptase polymerized chain reaction (RT-PCR). Maternal undernutrition inhibited maternal adrenal expression of P450 cholesterol side-chain cleavage enzyme (CYP11A1), 11 beta-hydroxylase (CYP11B1), aldosterone synthase (CYP11B2), and adrenocorticotropic hormone (ACTH) receptor (ACTH-R; MC2 gene) compared with control offspring. There was a marked downregulation in the expression of CYP11B1, CYP11B2, 11 ?-hydroxysteroid dehydrogenase type 1 and 2 (HSD1 and HSD2), CYP11A1, ACTH receptor, steroidogenic acute regulatory protein (STAR), and mineralocorticoid receptor (MCR; NR3C2 gene) mRNA in P1 MUN offspring (both genders), with no changes in glucocorticoid receptor (GCR). Quantitative immunohistochemical analysis confirmed the PCR data for GCR and MCR in P1 offspring and demonstrated lower expression of leptin receptor protein (Ob-Ra/Ob-Rb) and mRNA in P1 MUN offspring. In 9-month adult male MUN offspring, the expression of HSD1, CYP11A1, CYP11B2, Ob-Ra/Ob-Rb, and GCR mRNA were significantly upregulated with a trend toward an increase in ACTH-R and a decrease in 17 alpha-hydroxylase (CYP17A1) expression. In adult female MUN offspring, similar to males, the expression of CYP11A1, ACTH-R, and Ob-Rb mRNA were increased, whereas GCR and CYP17A1 mRNA were decreased. These results indicate that the adrenal gland is a target of nutritional programming. In utero undernutrition has a global suppressive effect on maternal and P1 offspring adrenal steroidogenic enzymes in association with reduced circulating corticosterone levels in P1 offspring, which may be secondary to a negative feedback from elevated maternal GC levels and or leptin levels in MUN dams. Gender-specific differences in steroidogenic enzyme expression were found in adult MUN offspring. The common finding of increased ACTH receptor expression in MUN adults of both genders suggests an increased sensitivity of these offspring to stress. PMID:21566243

Khorram, Naseem M; Magee, Thomas R; Wang, Chen; Desai, Mina; Ross, Michael; Khorram, Omid

2011-05-12

405

Maternal Undernutrition Programs Offspring Adrenal Expression of Steroidogenic Enzymes  

PubMed Central

The aim of this study was to determine the influence of maternal undernutrition (MUN) on maternal and offspring adrenal steoridogenic enzymes. Pregnant Sprague-Dawley rats were 50% food-restricted from day 10 of gestation until delivery. Control animals received ad libitum food. Offspring were killed on day 1 of life (P1) and at 9 months. We determined the messenger RNA (mRNA) expression of steroidogneic enzymes by real-time reverse transcriptase polymerized chain reaction (RT-PCR). Maternal undernutrition inhibited maternal adrenal expression of P450 cholesterol side-chain cleavage enzyme (CYP11A1), 11 beta-hydroxylase (CYP11B1), aldosterone synthase (CYP11B2), and adrenocorticotropic hormone (ACTH) receptor (ACTH-R; MC2 gene) compared with control offspring. There was a marked downregulation in the expression of CYP11B1, CYP11B2, 11 ?-hydroxysteroid dehydrogenase type 1 and 2 (HSD1 and HSD2), CYP11A1, ACTH receptor, steroidogenic acute regulatory protein (STAR), and mineralocorticoid receptor (MCR; NR3C2 gene) mRNA in P1 MUN offspring (both genders), with no changes in glucocorticoid receptor (GCR). Quantitative immunohistochemical analysis confirmed the PCR data for GCR and MCR in P1 offspring and demonstrated lower expression of leptin receptor protein (Ob-Ra/Ob-Rb) and mRNA in P1 MUN offspring. In 9-month adult male MUN offspring, the expression of HSD1, CYP11A1, CYP11B2, Ob-Ra/Ob-Rb, and GCR mRNA were significantly upregulated with a trend toward an increase in ACTH-R and a decrease in 17 alpha-hydroxylase (CYP17A1) expression. In adult female MUN offspring, similar to males, the expression of CYP11A1, ACTH-R, and Ob-Rb mRNA were increased, whereas GCR and CYP17A1 mRNA were decreased. These results indicate that the adrenal gland is a target of nutritional programming. In utero undernutrition has a global suppressive effect on maternal and P1 offspring adrenal steroidogenic enzymes in association with reduced circulating corticosterone levels in P1 offspring, which may be secondary to a negative feedback from elevated maternal GC levels and or leptin levels in MUN dams. Gender-specific differences in steroidogenic enzyme expression were found in adult MUN offspring. The common finding of increased ACTH receptor expression in MUN adults of both genders suggests an increased sensitivity of these offspring to stress.

Khorram, Naseem M.; Magee, Thomas R.; Wang, Chen; Desai, Mina; Ross, Michael; Khorram, Omid

2011-01-01

406

Cosmic ray produced nitrogen in extra terrestrial matter  

Microsoft Academic Search

Production rates of15N by both solar cosmic rays (SCR) and galactic cosmic rays (GCR) have been calculated for moon, as well as meteorites of various\\u000a sizes. Our production rates of15N which considered both the reaction channels16O(p, pn)15O and16O(p, 2p)15N separately are about 30% higher than those by Reedy (1981) who considered only the channel16O(p, pn)15O and used an empirical scaling

K. J. Mathew; S. V. S. Murty

1993-01-01

407

The enthalpies of vaporization and sublimation of exo- and endo-tetrahydrodicyclopentadienes at T=298.15 K  

Microsoft Academic Search

The vaporization enthalpies {?glHm (298.15K)} of endo- and exo-tetrahydrodicyclopentadiene (THDCPD) have been measured by correlation gas chromatography. Values of (50.2±2.3)kJ·mol?1 and (49.1±2.3)kJ·mol?1 have been obtained for the endo and exo isomers, respectively. The sublimation enthalpy of the endo isomer {?gcrHm(298.15K)=(51.2±2.4)kJ·mol?1} has been obtained by combining fusion and vaporization enthalpies adjusted as necessary to T=298.15K. Low-temperature d.s.c. studies of both isomers

Michael J. Zehe; Dorothea Hillesheim; Gary Nichols

2002-01-01

408

Personnel radiation exposure in HTGR plants  

SciTech Connect

Occupational radiation exposures in high-temperature gas-cooled reactor (HTGR) plants were assessed. The expected rate of dose accumulations for a large HTGR steam cycle (HTGR-SC) unit is 0.07 man-rem/MW(e)y, while the design basis is 0.17 man-rem/MW(e)y. The comparable figure for actual light water reactor (LWR) experience is 1.3 man-rem/MW(e)y. The favorable HTGR occupational exposure is supported by results from the Peach Bottom Unit No. 1 HTGR and Fort St. Vrain HTGR plants and by operating experience at British gas-cooled reactor (GCR) stations.

Su, S.; Engholm, B.A.

1980-01-01

409

Numerical simulations of production rates for 10Be, 26Al and 14C in extraterrestrial matter using the MCNPX code  

NASA Astrophysics Data System (ADS)

Numerical simulations of production rates for cosmogenic 10Be, 26Al and 14C in well-documented samples from the meteorite Knyahinya and the Apollo 15 deep core were performed using the MCNPX (Monte Carlo N Particle eXtended) code for cosmic-ray interactions. Comparisons of experimental measurements and our numerical simulations were done to test our calculations and show that the numerical simulations reproduce well experimental measurements. The effective fluxes of GCR proton determined from our comparisons are important parameters for future calculations. Additional measurements of some radionuclide activities and of cross sections for neutron-induced reactions are needed.

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

2010-04-01

410

Particle Flux Variations at Solar Minimum: Comparisons of ACE/CRIS Data with Model Calculations  

NASA Astrophysics Data System (ADS)

During the current solar minimum condition, galactic cosmic ray (GCR) flux of several particle species reached peak values, as expected. Model calculations for the current solar minimum condition (2009-2010) are compared with the measurements from the ACE/CRIS instrument. During the first half of 2010, oxygen particle flux decreases as anticipated and closely follows the predicted model calculations. However, nitrogen flux variation did not show the expected trends. Implications of these particle flux variations will be presented and discussed in the context of dose estimations for intended human explorations.

Erickson, G. M.; Saganti, P. B.; Cudnik, B.; Scott-Turner, A.

2010-12-01

411

On the interaction of methyl azide (CH3N3) ices with ionizing radiation: formation of methanimine (CH2NH), hydrogen cyanide (HCN), and hydrogen isocyanide (HNC).  

PubMed

Methyl azide (CH(3)N(3)) might be a potential precursor in the synthesis of prebiotic molecules via nonequilibrium reactions on interstellar ices initiated by energetic galactic cosmic rays (GCR) and photons. Here, we investigate the effects of energetic electrons as formed in the track of cosmic ray particles and 193 nm photons with solid methyl azide at 10 K and the inherent formation of methanimine (CH(2)NH), hydrogen cyanide (HCN), and hydrogen isocyanide (HNC). We present a systematic kinetic study and outline feasible reaction pathways to these molecules. These processes might be also important in solar system analogue ices. PMID:21162584

Quinto-Hernandez, Alfredo; Wodtke, Alec M; Bennett, Chris J; Kim, Y Seol; Kaiser, Ralf I

2010-12-17

412

Raman spectroscopy of magnetic excitations in diluted magnetic II-VI semiconductors and in ruby  

Microsoft Academic Search

Raman electron paramagnetic resonance(Raman-EPR) of the transitions due to the spin-flip of the 3d electrons of Cr+ in Zn1-xCr xTe and Cd1-x CrxTe are observed at hoPM=g( Cr+)muBB with g(Cr+)=2.0041 +\\/- 0.0095 and 2.0039 +\\/- 0.0093, respectively. Raman lines appear at o LO +\\/- noPM, n=1,2 and 3, resulting from the strong Frohlich interaction with the zone center longitudinal optic

Xiangshun Lu

2008-01-01

413

Gas Core Reactor with Magnetohydrodynamic Power System and Cascading Power Cycle  

SciTech Connect

The U.S. Department of Energy initiative Generation IV aim is to produce an entire nuclear energy production system with next-generation features for certification before 2030. A Generation IV-capable system must have superior sustainability, safety and reliability, and economic cost advantages in comparison with third generation light water reactors (LWRs). A gas core reactor (GCR) with magnetohydrodynamic (MHD) power converter and cascading power cycle forms the basis for a Generation IV concept that is expected to set the upper performance limits in sustainability and power conversion efficiency among all existing and proposed fission powered systems. A gaseous core reactor delivering thousands of megawatt fission power acts as the heat source for a high-temperature MHD power converter. A uranium tetrafluoride fuel mix, with {approx}95% mol fraction helium gas, provides a stable working fluid for the primary MHD Brayton cycle. The hot working fluid exiting a topping cycle MHD generator has sufficient heat to drive a conventional helium Brayton cycle with 35% thermal efficiency as well as a superheated steam Rankine cycle, with up to 40% efficiency, which recovers the waste heat from the intermediate Brayton cycle. A combined cycle efficiency of close to 70% can be achieved with only a modest MHD topping cycle efficiency. The high-temperature direct-energy conversion capability of an MHD dynamo combined with an already sophisticated steam-powered turbine industry knowledge base allows the cascading cycle design to achieve breakthrough first-law energy efficiencies previously unheard of in the nuclear power industry. Although simple in concept, the gas core reactor design has not achieved the state of technological maturity that established high-temperature gas-cooled reactors and high-temperature molten salt core reactors have pioneered. However, the GCR-MHD concept has considerable promise; for example, like molten salt reactors the fuel is continuously cycled, allowing high burnup, continuous burning of actinides, and hence greatly improved fuel utilization. The fuel inventory is two orders of magnitude lower than LWRs of comparable power output, and fissile plutonium production is likewise lower than in spent LWR fuel. Besides these features, specific GCR-MHD design challenges such as fission enhanced gas conductivity of the MHD partially ionized gas, GCR safety issues and related engineering problems are discussed.

Smith, Blair M.; Anghaie, Samim [University of Florida (United States)

2004-03-15

414

Gas Core Reactor-MHD Power System with Cascading Power Cycle  

SciTech Connect

The US Department of Energy initiative Gen-IV aim is to produce an entire nuclear energy production system with next generation features for certification before 2030. A Generation 4 capable system must have superior sustainability, safety and reliability, and economic cost advantages in comparison with third generation light water reactors. A gas core reactor (GCR) with magnetohydrodynamic (MHD) power converter and cascading power cycle forms the basis for a Generation IV concept that is expected to set the upper performance limits in sustainability and power conversion efficiency among all existing and proposed fission powered systems. A gaseous core reactor delivering 1000's MW fission power acts as the heat source for a high temperature magnetohydrodynamic power converter. A uranium tetrafluoride fuel mix, with {approx}95% mole fraction helium gas, provides a stable working fluid for the primary MHD-Brayton cycle. A helium Brayton cycle extracts waste heat from the MHD generator with about 20% energy efficiency, but the low temperature side is still hot enough ({approx}1600 K) to drive a second conventional helium Brayton cycle with about 35% efficiency. There is enough heat at the low temperature side of the He-Brayton cycle to generate steam, and so another heat recovery cycle can be added, this time a Rankine steam cycle with up to 40% efficiency. The proof of concept does not require a tremendously efficient (first law) MHD cycle, the high temperature direct energy conversion capability of an MHD dynamo, combined with already sophisticated steam powered turbine industry knowledge base allows the cascading cycle design to achieve break-through first law energy efficiencies previously unheard of in the nuclear power industry. Although simple in concept, the gas core reactor design has not achieved the state of technological maturity that, say, molten salt or high-temperature gas-cooled reactors have pioneered. However, even on paper the GCR-MHD concept holds considerable promise, for example, like molten salt reactors the fuel is continuously cycled, allowing high-burnup, and continuous burning of actinides, and hence greatly improved fuel utilization. The fuel inventory is two orders of magnitude lower than LWR's of comparable power output and fissile plutonium production is likewise lower than in spent LWR fuel. Besides these features this paper discusses specific GCR-MHD design challenges such as fission enhanced gas conductivity in the MHD channel, GCR safety issues and related engineering problems. (authors)

Smith, Blair M.; Anghaie, Samim; Knight, Travis W. [Innovative Nuclear Space Power and Propulsion Institute, University of Florida, PO Box 116502, Gainesville, FL, 32611 (United States)

2002-07-01

415

Evidence of nearby supernovae affecting life on Earth  

NASA Astrophysics Data System (ADS)

Observations of open star clusters in the solar neighbourhood are used to calculate local supernova (SN) rates for the past 510 Myr. Peaks in the SN rates match passages of the Sun through periods of locally increased cluster formation which could be caused by spiral arms of the Galaxy. A statistical analysis indicates that the Solar system has experienced many large short-term increases in the flux of Galactic cosmic rays (GCR) from nearby SNe. The hypothesis that a high GCR flux should coincide with cold conditions on the Earth is borne out by comparing the general geological record of climate over the past 510 Myr with the fluctuating local SN rates. Surprisingly, a simple combination of tectonics (long-term changes in sea level) and astrophysical activity (SN rates) largely accounts for the observed variations in marine biodiversity over the past 510 Myr. An inverse correspondence between SN rates and carbon dioxide (CO2) levels is discussed in terms of a possible drawdown of CO2 by enhanced bio-productivity in oceans that are better fertilized in cold conditions - a hypothesis that is not contradicted by data on the relative abundance of the heavy isotope of carbon, 13C.

Svensmark, Henrik

2012-06-01

416

Time profile of cosmic radiation exposure during the EXPOSE-E mission: the R3DE instrument.  

PubMed

The aim of this paper is to present the time profile of cosmic radiation exposure obtained by the Radiation Risk Radiometer-Dosimeter during the EXPOSE-E mission in the European Technology Exposure Facility on the International Space Station's Columbus module. Another aim is to make the obtained results available to other EXPOSE-E teams for use in their data analysis. Radiation Risk Radiometer-Dosimeter is a low-mass and small-dimension automatic device that measures solar radiation in four channels and cosmic ionizing radiation as well. The main results of the present study include the following: (1) three different radiation sources were detected and quantified-galactic cosmic rays (GCR), energetic protons from the South Atlantic Anomaly (SAA) region of the inner radiation belt, and energetic electrons from the outer radiation belt (ORB); (2) the highest daily averaged absorbed dose rate of 426 ?Gy d(-1) came from SAA protons; (3) GCR delivered a much smaller daily absorbed dose rate of 91.1 ?Gy d(-1), and the ORB source delivered only 8.6 ?Gy d(-1). The analysis of the UV and temperature data is a subject of another article (Schuster et al., 2012 ). PMID:22680687

Dachev, Tsvetan; Horneck, Gerda; Häder, Donat-Peter; Schuster, Martin; Richter, Peter; Lebert, Michael; Demets, Rene

2012-05-01

417

Radiation environment at LEO orbits: MC simulation and experimental data.  

NASA Astrophysics Data System (ADS)

The evaluations of the different components of the radiation environment in spacecraft, both in LEO orbits and in deep space is of great importance because the biological effect on humans and the risk for instrumentation strongly depends on the kind of radiation (high or low LET). That is important especially in view of long term manned or unmanned space missions, (mission to Mars, solar system exploration). The study of space radiation field is extremely complex and not completely solved till today. Given the complexity of the radiation field, an accurate dose evaluation should be considered an indispensable part of any space mission. Two simulation codes (MCNPX and GEANT4) have been used to assess the secondary radiation inside FO-TON M3 satellite and ISS. The energy spectra of primary radiation at LEO orbits have been modelled by using various tools (SPENVIS, OMERE, CREME96) considering separately Van Allen protons, the GCR protons and the GCR alpha particles. This data are used as input for the two MC codes and transported inside the spacecraft. The results of two calculation meth-ods have been compared. Moreover some experimental results previously obtained on FOTON M3 satellite by using TLD, Bubble dosimeter and LIULIN detector are considered to check the performances of the two codes. Finally the same experimental device are at present collecting data on the ISS (ASI experiment BIOKIS -nDOSE) and at the end of the mission the results will be compared with the calculation.

Zanini, Alba; Borla, Oscar; Damasso, Mario; Falzetta, Giuseppe

418

Discovery of a Significant Magnetic CV Population in the Galactic Center Region  

NASA Astrophysics Data System (ADS)

The large number (>3000) of the low-luminosity (10^30-33 erg/s at 8 kpc) X-ray sources discovered in the Galactic Center Region (GCR) are of great importance for understanding the evolutionary history of compact objects, accreting binaries and the inner Galaxy. We have identified 10 periodic X-ray sources and 11 candidates out of 843 X-ray sources (net counts>=50) discovered in the 1 Ms Chandra/ACIS-I exposure of the low extinction "Limiting Window" field 1.4 deg south of the Galactic Center. Their period distribution, hard X-ray spectra, and high X-ray-to-optical flux ratios are typical of magnetic cataclysmic variables (MCVs), resembling those of the periodic sources found in the Sgr A* field. When inspected in the detail, however, their properties appear to fit better with a rare sub-class of MCVs, near synchronous MCVs, which is sometimes considered a missing link in the evolution of MCVs from intermediate polars to polars. Our simulations for completeness for discovery of such sources, with periods in the range 150 - 10^4 sec, suggest that 20-30% of the hard X-ray sources in the LW field (and probably Sgr A*) with significant low energy absorption (and thus located in the GCR) are periodic, implying a large population of MCVs in the Bulge.

Hong, JaeSub; Grindlay, J.; van den Berg, M.; Servillat, M.; Zhao, P.

2011-05-01

419

Pathologic Role of Stressed-Induced Glucocorticoids in Drug-Induced Liver Injury in Mice  

PubMed Central

We previously reported that acetaminophen (APAP)-induced liver injury (AILI) in mice is associated with a rise in serum levels of the glucocorticoid (GC), corticosterone. In the current study, we provide evidence that endogenous GC play a pathologic role in AILI. Specifically, pretreatment of mice with the GC receptor (GCR) inhibitor, RU486 (mifepristrone), protected normal but not adrenalectomized mice from AILI, while pretreatment with dexamethasone, a synthetic GC, exacerbated AILI. RU486 did not affect the depletion of whole liver reduced GSH or the formation of APAP-protein adducts. It also had no effects on the formation of reactive oxygen species or the depletion of mitochondrial GSH or ATP. While RU486 pretreatment also protected against halothane-induced liver injury, it exacerbated concanavalin A (ConA)- and carbon tetrachloride (CCl4)-induced liver injury, demonstrating the complexity of GC effects in different types of liver injury. Conclusion: These results suggest that under certain conditions, elevated levels of GC might represent a previously unappreciated risk factor for liver injury caused by APAP and other drugs through the diverse biological processes regulated by GCR.

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

2010-01-01

420

The response of a spherical tissue-equivalent proportional counter to 56-Fe particles from 200-1000 MeV/nucleon  

SciTech Connect

The radiation environment aboard the space shuttle and the International Space Station includes high-Z and high-energy (HZE) particles that are part of the galactic cosmic radiation (GCR) spectrum. Iron-56 is considered to be one of the most biologically important parts of the GCR spectrum. Tissue-equivalent proportional counters (TEPC) are used as active dosimeters on manned space flights. These TEPC's are further used to determine average quality factor for each space mission. A TEPC simulating a 1 micron diameter sphere of tissue was exposed as part of a particle spectrometer to iron-56 at energies from 200-1000 MeV/nucleon. The response of TEPC in terms of frequency-averaged lineal energy, dose-averaged lineal energy, as well as energy deposited at different impact parameters through detector was determined for six different incident energies of iron-56 in this energy range. Calculations determined that charged particle equilibrium was achieved for each of the six experiments. Energy depositions at different impact parameters were calculated using a radial dose distribution model and the results compared to experimental data.

Gersey, Bradford B.; Borak, Thomas B.; Guetersloh, Stephen B.; Zeitlin, Cary J.; Miller, J.; Heilbronn, L.; Murakami, T.; Iwata, Y.

2001-09-04

421

Irradiation of the moon by galactic cosmic rays and other particles  

NASA Astrophysics Data System (ADS)

Men and sensitive instruments on a lunar base can be profoundly affected by the radiation environment of the moon. The ionizing radiation incident upon the lunar surface is comprised of the galactic cosmic rays (GCR) and energetic particles accelerated in the solar neighborhood. The latter consist mainly of solar energetic particles (SEP) from flares and of other particles energized in the heliosphere. The cosmic radiation bombarding the moon consists overwhelmingly of relativistic and near-relativistic atomic nuclei ranging in energy from 10 to the 8th to 10 to the 20th eV, approximately 98.6 percent of which consists of hydrogen and helium. The remainder spans the rest of the periodic table, with conspicuous peaks in abundance at C, O, Ne, Mg, Si, and Fe. The GCR composition is roughly similar to that of the sun, with some notable differences. Differential energy spectra and composition of cosmic rays as well as the intensities, composition, and the spectra of SEP and particles accelerated in the heliosphere are reviewed. Also summarized are the analytic models developed by the Naval Research Laboratory group to describe the energy spectra and elemental compositions of the various components.

Adams, J. H., Jr.; Shapiro, M. M.

422

Aging and epigenetics: longitudinal changes in gene-specific DNA methylation.  

PubMed

DNA methylation has been associated with age-related disease. Intra-individual changes in gene-specific DNA methylation over time in a community-based cohort has not been well described. We estimated the change in DNA methylation due to aging for nine genes in an elderly, community-dwelling cohort of men. Seven hundred and eighty four men from the Veterans Administration Normative Aging Study who were living in metropolitan Boston from 1999-2009 donated a blood sample for DNA methylation analysis at clinical examinations repeated at approximately 3-5 year intervals. We used mixed effects regression models. Aging was significantly associated with decreased methylation of GCR, iNOS and TLR2 and with increased methylation of IFN?, F3, CRAT and OGG. Obstructive pulmonary disease at baseline modified the effect of aging on methylation of IFN? (interaction p = 0.04). For participants who had obstructive pulmonary disease at their baseline visit, the rate of change of methylation of IFN? was -0.05% 5-methyl-cytosine (5-mC) per year (95% CI: -0.22, 0.13), but was 0.14% 5-mC per year (95% CI: 0.05, 0.24) for those without this condition. Models with random slopes indicated significant heterogeneity in the effect of aging on methylation of GCR, iNOS and OGG. These findings suggest that DNA methylation may reflect differential biological aging. PMID:22207354

Madrigano, Jaime; Baccarelli, Andrea; Mittleman, Murray A; Sparrow, David; Vokonas, Pantel S; Tarantini, Letizia; Schwartz, Joel

2012-01-01

423

Global lightning formation at a minimum and maximum of solar activity according to the observations of the Schumann resonance on the Kola Peninsula  

NASA Astrophysics Data System (ADS)

On the basis of the two-component measurements of the atmospheric noise electromagnetic field on the Kola Peninsula, a change in the first Schumann resonance (SR-1) as an indicator of global lightning formation is studied depending on the level of galactic cosmic rays (GCRs). It is found that the effect of GCRs is most evident during five months: in January and from September to December; in this case the SR-1 intensity in 2001 was higher than the level of 2007 by a factor of 1.5 and more. This effect almost disappears when the regime of the Northern Hemisphere changes into the summer regime. It is assumed that an increase in the GCR intensity results in an increase in the lightning occurrence frequency; however, the probability that the power of each lightning stroke decreases owing to an early disruption of the charge separation and accumulation processes in a thundercloud increases; on the contrary, a decrease in the GCR intensity decreases lightning stroke occurrence frequency and simultaneously increases the probability of accumulating a higher energy by a thundercloud and increasing the lightning power to the maximum possible values.

Beloglazov, M. I.; Akhmetov, O. I.

2010-12-01

424

Monte Carlo analysis of pion contribution to absorbed dose from Galactic cosmic rays  

NASA Astrophysics Data System (ADS)

Accurate knowledge of the physics of interaction, particle production and transport is necessary to estimate the radiation damage to equipment used on spacecraft and the biological effects of space radiation. For long duration astronaut missions, both on the International Space Station and the planned manned missions to Moon and Mars, the shielding strategy must include a comprehensive knowledge of the secondary radiation environment. The distribution of absorbed dose and dose equivalent is a function of the type, energy and population of these secondary products. Galactic cosmic rays (GCR) comprised of protons and heavier nuclei have energies from a few MeV per nucleon to the ZeV region, with the spectra reaching flux maxima in the hundreds of MeV range. Therefore, the MeV-GeV region is most important for space radiation. Coincidentally, the pion production energy threshold is about 280 MeV. The question naturally arises as to how important these particles are with respect to space radiation problems. The space radiation transport code, HZETRN (High charge (Z) and Energy TRaNsport), currently used by NASA, performs neutron, proton and heavy ion transport explicitly, but it does not take into account the production and transport of mesons, photons and leptons. In this paper, we present results from the Monte Carlo code MCNPX (Monte Carlo N-Particle eXtended), showing the effect of leptons and mesons when they are produced and transported in a GCR environment.

Aghara, S. K.; Blattnig, S. R.; Norbury, J. W.; Singleterry, R. C.

2009-04-01

425

Constraints on the Origin of Galactic Cosmic Rays from Direct Measurements of Isotopic and Elemental Abundances  

NASA Astrophysics Data System (ADS)

Recent measurements of galactic cosmic ray (GCR) isotopic and elemental abundances have resulted in constraints on models of the origin of GCRs. The measurement of ^{59}Ni by the Cosmic Ray Isotope Spectrometer (CRIS) on the NASA Advanced Composition Explorer (ACE) has shown that there must be >˜10^{5} years between nucleosynthesis and acceleration. Measurements of a range of isotope ratios, most importantly ^{22}Ne/^{20}Ne and ^{58}Fe/^{56}Fe, have shown that the composition is consistent with source material that is a mix of ˜80% ISM (with Solar System abundances) and 20% outflow from massive stars. Data from the Trans-Iron Galactic Element Recorder (TIGER) and the ACE-CRIS experiments both show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to an ˜80%/20% mix rather than pure ISM, that they have similar slopes, and that refractory elements are preferentially accelerated by a factor of ˜4 over volatile elements. We discuss these observations and conclude that our constraints are consistent with a GCR origin in OB associations. This research was supported by NASA under Grants NNX08AI11G and NNX09AC17G, and by NSF under Grant 0807356

Rauch, Brian

2012-07-01

426

Space radiation protection: comparison of effective dose to bone marrow dose equivalent.  

PubMed

In many instances, bone marrow dose equivalents averaged over the entire body have been used as a surrogate for whole-body dose equivalents in space radiation protection studies. However, career radiation limits for space missions are expressed as effective doses. This study compares calculations of effective doses to average bone marrow dose equivalents for several large solar particle events (SPEs) and annual galactic cosmic ray (GCR) spectra, in order to examine the suitability of substituting bone marrow dose equivalents for effective doses. Organ dose equivalents are computed for all radiosensitive organs listed in NCRP Report 116 using the BRYNTRN and HZETRN space radiation transport codes and the Computerized Anatomical Man (CAM) model. These organ dose equivalents are then weighted with the appropriate tissue weighting factors to obtain effective doses. Various thicknesses of aluminum shielding, which are representative of nominal spacecraft and SPE storm shelter configurations, are used in the analyses. For all SPE configurations, the average bone marrow dose equivalent is considerably less than the calculated effective dose. For comparisons of the GCR, there is less than a ten percent difference between the two methods. In all cases, the gonads made up the largest percentage of the effective dose. PMID:12793744

Hoff, Jennifer L; Townsend, Lawrence W; Zapp, E Neal

2002-12-01

427

Acceleration of Galactic Cosmic Rays in the Interstellar Medium  

NASA Astrophysics Data System (ADS)

Challenges have arisen to diffusive shock acceleration as the primary means to accelerate galactic cosmic rays (GCRs) in the interstellar medium. Diffusive shock acceleration is also under challenge in the heliosphere, where at least the simple application of diffusive shock acceleration cannot account for observations. In the heliosphere, a new acceleration mechanism has been invented—a pump mechanism, driven by ambient turbulence, in which particles are pumped up in energy out of a low-energy core particle population through a series of adiabatic compressions and expansions—that can account for observations not only at shocks but in quiet conditions in the solar wind and throughout the heliosheath. In this paper, the pump mechanism is applied to the acceleration of GCRs in the interstellar medium. With relatively straightforward assumptions about the magnetic field in the interstellar medium, and how GCRs propagate in this field, the pump mechanism yields (1) the overall shape of the GCR spectrum, a power law in particle kinetic energy, with a break at the so-called knee in the GCR spectrum to a slightly steeper power-law spectrum. (2) The rigidity dependence of the H/He ratio observed from the PAMELA satellite instrument.

Fisk, L. A.; Gloeckler, G.

2012-01-01

428

Human exposure to space radiation: role of primary and secondary particles.  

PubMed

Human exposure to space radiation implies two kinds of risk, both stochastic and deterministic. Shielding optimisation therefore represents a crucial goal for long-term missions, especially in deep space. In this context, the use of radiation transport codes coupled with anthropomorphic phantoms allows to simulate typical radiation exposures for astronauts behind different shielding, and to calculate doses to different organs. In this work, the FLUKA Monte Carlo code and two phantoms, a mathematical model and a voxel model, were used, taking the Galactic Cosmic Rays (GCR) spectra from the model of Badhwar and O'Neill. The time integral spectral proton fluence of the August 1972 Solar Particle Event (SPE) was represented by an exponential function. For each aluminium shield thickness, besides total doses the contributions from primary and secondary particles for different organs and tissues were calculated separately. More specifically, organ-averaged absorbed doses, dose equivalents and a form of 'biological dose', defined on the basis of initial (clustered) DNA damage, were calculated. As expected, the SPE doses dramatically decreased with increasing shielding, and doses in internal organs were lower than in skin. The contribution of secondary particles to SPE doses was almost negligible; however it is of note that, at high shielding (10 g cm(-2)), most of the secondaries are neutrons. GCR organ doses remained roughly constant with increasing Al shielding. In contrast to SPE results, for the case of cosmic rays, secondary particles accounted for a significant fraction of the total dose. PMID:17151013

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

2006-12-06

429

Lunar radiation environment: a study by using Kaguya gamma-ray spectrometer and Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

We have continued to improve the estimation of radiation dose on the Moon based on observation by remote sensing and calculation of the transportation of cosmic-ray particles in the lunar materials in order to provide basic data for a future manned lunar exploration. On the lunar surface, the dose of primary galactic cosmic rays (pGCR) is the most significant and the contributions of neutrons and gamma rays are relatively small and are approximately 10% and 1% of that of pGCR, respectively. However, these percentages are changed by use of thick shieldings and also geographical feature of the lunar surface, such as margin of a huge boulder, bottom of a pit, inside of a possible lava tube. In this case, the dose by pGCRs is moderated and the contributions of neutrons and gamma rays relatively increase. Here, we show the recent estimation of spatial variation of the lunar dose due to gamma ray and neutrons measured by Kaguya gamma-ray spectrometer. The energy spectrum of gamma rays from the lunar surface are precisely measured by a germanium (Ge) gamma-ray spectrometer onboard the Japanese lunar orbiter (Kaguya/SELENE). The flux of fast neutrons from the lunar surface was also measured by detecting the characteristic gamma rays due to the neutron inelastic reaction with the Ge of the spectrometer, that is 72Ge(n, n'g)72Ge. The estimation of radiation dose on the Moon based on Monte Carlo simulation will also be presented.

Kobayashi, Shingo; Hayatsu, Kanako; Uchihori, Yukio; Hareyama, Makoto; Hasebe, Nobuyuki; Fujibayashi, Yukari

2012-07-01

430

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

2013-09-24

431

Evaluation of a combined electrostatic and magnetostatic configuration for active space-radiation shielding  

NASA Astrophysics Data System (ADS)

Developing successful and optimal solutions to mitigating the hazards of severe space radiation in deep space long duration missions is critical for the success of deep-space explorations. A recent report (Tripathi et al., 2008) had explored the feasibility of using electrostatic shielding. Here, we continue to extend the electrostatic shielding strategy and examine a hybrid configuration that utilizes both electrostatic and magnetostatic fields. The main advantages of this system are shown to be: (i) a much better shielding and repulsion of incident ions from both solar particle events (SPE) and galactic cosmic rays (GCR), (ii) reductions in the power requirement for re-charging the electrostatic sub-system, and (iii) low requirements of the magnetic fields that are well below the thresholds set for health and safety for long-term exposures. Furthermore, our results show transmission levels reduced to levels as low as 30% for energies around 1000 MeV, and near total elimination of SPE radiation by these hybrid configurations. It is also shown that the power needed to replenish the electrostatic charges due to particle hits from the GCR and SPE radiation is minimal.

Joshi, Ravindra P.; Qiu, Hao; Tripathi, Ram K.

2013-05-01

432

Fragmentation cross sections of 28Si at beam energies from 290A to 1200A MeV  

NASA Astrophysics Data System (ADS)

In planning for long-duration spaceflight, it will be important to accurately model the exposure of astronauts to heavy ions in the galactic cosmic rays (GCR). As part of an ongoing effort to improve heavy-ion transport codes that will be used in designing future spacecraft and habitats, fragmentation cross sections of 28Si have been measured using beams with extracted energies from 290A to 1200A MeV, spanning most of the peak region of the energy distribution of silicon ions in the GCR. Results were obtained for six elemental targets: hydrogen, carbon, aluminum, copper, tin, and lead. The charge-changing cross sections are found to be energy-independent within the experimental uncertainties, except for those on the hydrogen target. Cross sections for the production of the heaviest fragments are found to decrease slightly with increasing energy for lighter targets, but increase with energy for tin and lead targets. The cross sections are compared to previous measurements at similar energies, and to predictions of the NUCFRG2 model used by NASA to evaluate radiation exposures in flight. For charge-changing cross sections, reasonable agreement is found between the present experiment and those of Webber et al. and Flesch et al., and NUCFRG2 agrees with the data to within 3% in most cases. Fragment cross sections show less agreement between experiments, and there are substantial differences between NUCFRG2 predictions and the data.

Zeitlin, C.; Fukumura, A.; Guetersloh, S. B.; Heilbronn, L. H.; Iwata, Y.; Miller, J.; Murakami, T.

2007-03-01

433

Reactive nano-epoxy matrix and the UHMWPE fiber composites for cosmic radiation shielding  

NASA Astrophysics Data System (ADS)

Cosmic radiation shielding properties are important for spacecraft. Hydrogenous materials such as polyethylene have been shown effective against galactic cosmic rays (GCR) and solar energetic particles. Ultrahigh molecular weight polyethylene (UHMWPE) fibers have advanced mechanical and physical properties, which are very valuable for NASA missions. Unfortunately, poor interface in the UHMWPE fiber/polymer matrix hinders the structural integrity of the composites, and restricts the effectiveness of radiation shielding for practical applications. Fiber treatment methods can not only incur an extra cost for manufacturing the composite structures, but also may sacrifice intrinsic properties of the fibers. In our study, we fabricated a reactive nano-epoxy matrix with reactive graphitic nanofibers, which showed enhanced mechanical (including strength, modulus and toughness) and thermal properties (higher Tg, stable CTE, and higher ageing resistant), as well as wetting and adhesion ability to UHMWPE fibers. 1 GeV/nucleon 35Cl ions, high energy ions for the complex GCR heavy ion radiation field, was used for the radiation tests. The results showed that the radiation shielding property was not reduced by the addition of graphitic nanofibers. The studies indicated that the UHMWPE fiber/nano-epoxy will have potential in manufacturing more durable space composites and structures.

Zhong, W. H.; Miller, J.

2007-10-01

434

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

435

Gross chromosomal rearrangement mediated by DNA replication in stressed cells: evidence from Escherichia coli  

PubMed Central

Gross chromosomal rearrangements (GCRs), or changes in chromosome structure, play central roles in evolution and are central to cancer formation and progression. GCRs underlie copy number variation (CNV), and therefore genomic disorders that stem from CNV. We study amplification in Escherichia coli as a model system to understand mechanisms and circumstances of GCR formation. Here, we summarize observations that led us to postulate that GCR occurs by a replicative mechanism as part of activated stress responses. We report that we do not find RecA to be downregulated by stress on a population basis and that constitutive expression of RecA does not inhibit amplification as would be expected if downregulation of RecA made cells permissive for nonhomologous recombination. Strains deleted for the genes for three proteins that inhibit RecA activity, psiB, dinI, and recX, all show unaltered amplification, suggesting that if they do downregulate RecA indirectly, it does not promote amplification.

Moore, J. M.; Wimberly, Hallie; Thornton, P. C.; Rosenberg, Susan M.; Hastings, P. J.

2012-01-01

436

Synchronized Northern Hemisphere climate change and solar magnetic cycles during the Maunder Minimum  

PubMed Central

The Maunder Minimum (A.D. 1645–1715) is a useful period to investigate possible sun–climate linkages as sunspots became exceedingly rare and the characteristics of solar cycles were different from those of today. Here, we report annual variations in the oxygen isotopic composition (?18O) of tree-ring cellulose in central Japan during the Maunder Minimum. We were able to explore possible sun–climate connections through high-temporal resolution solar activity (radiocarbon contents; ?14C) and climate (?18O) isotope records derived from annual tree rings. The tree-ring ?18O record in Japan shows distinct negative ?18O spikes (wetter rainy seasons) coinciding with rapid cooling in Greenland and with decreases in Northern Hemisphere mean temperature at around minima of decadal solar cycles. We have determined that the climate signals in all three records strongly correlate with changes in the polarity of solar dipole magnetic field, suggesting a causal link to galactic cosmic rays (GCRs). These findings are further supported by a comparison between the interannual patterns of tree-ring ?18O record and the GCR flux reconstructed by an ice-core 10Be record. Therefore, the variation of GCR flux associated with the multidecadal cycles of solar magnetic field seem to be causally related to the significant and widespread climate changes at least during the Maunder Minimum.

Yamaguchi, Yasuhiko T.; Yokoyama, Yusuke; Miyahara, Hiroko; Sho, Kenjiro; Nakatsuka, Takeshi

2010-01-01

437

Be-7 nuclei produced by galactic cosmic rays and solar energetic particles in the earth's atmosphere  

NASA Astrophysics Data System (ADS)

Be-7 radioactive nuclei with a half-life of 53.3 days result from spallation reactions of galactic cosmic rays(GCR) and solar energetic particles (SEP) with N and O nuclei in the Earth's atmosphere. We calculate the average global production of Be-7 in the atmosphere by GCR and SEP The result indicates that an intense SEP event produces a large amount of Be-7 in the polar stratosphere and part of them could be transported to the surface at lower latitudes. The ground-level measurement of Be-7 in Japan exhibits the possibility of enhancement in the Be-7 radioactivity associated with the intense SEP event on July 14, 2000. In addition, the present experiment shows seasonal variations in the surface Be-7 concentration which peaks in spring and autumn. We discuss the possible air mass mixing between the stratosphere and troposphere to explain the measured seasonal variations. The surface concentration of Pb-210 nuclei indicates a similar trend to that of Be-7 and we suggest two possible explanations.

Yoshimori, M.; Hirayama, H.; Mori, S.; Sasaki, K.; Sakurai, H.

438

Actinide and Ultra-Heavy Abundances in the Local Galactic Cosmic Rays: An Analysis of the Results from the LDEF Ultra-Heavy Cosmic-Ray Experiment  

NASA Astrophysics Data System (ADS)

The LDEF Ultra-Heavy Cosmic-Ray Experiment (UHCRE) detected Galactic cosmic rays (GCRs) of charge Z >= 70 in Earth orbit with an exposure factor of 170 m2 sr yr, much larger than any other experiment. The major results include the first statistically significant uniform sample of GCR actinides with 35 events passing quality cuts, evidence for the existence of transuranic nuclei in the GCR with one 96Cm candidate event, and a low 82Pb/78Pt ratio consistent with other experiments. The probability of the existence of a transuranic component is estimated as 96%, while the most likely 92U/90Th ratio is found to be 0.4 within a wide 70% confidence interval ranging from 0 to 0.96. Overall, the results are consistent with a volatility-based acceleration bias and source material which is mainly ordinary interstellar medium material with some recent contamination by freshly synthesized material. Uncertainty in the key 92U/90Th ratio is dominated by statistical errors resulting from the small sample size and any improved determination will thus require an experiment with a substantially larger exposure factor than the UHCRE.

Donnelly, J.; Thompson, A.; O'Sullivan, D.; Daly, J.; Drury, L.; Domingo, V.; Wenzel, K.-P.

2012-03-01

439

ACTINIDE AND ULTRA-HEAVY ABUNDANCES IN THE LOCAL GALACTIC COSMIC RAYS: AN ANALYSIS OF THE RESULTS FROM THE LDEF ULTRA-HEAVY COSMIC-RAY EXPERIMENT  

SciTech Connect

The LDEF Ultra-Heavy Cosmic-Ray Experiment (UHCRE) detected Galactic cosmic rays (GCRs) of charge Z {>=} 70 in Earth orbit with an exposure factor of 170 m{sup 2} sr yr, much larger than any other experiment. The major results include the first statistically significant uniform sample of GCR actinides with 35 events passing quality cuts, evidence for the existence of transuranic nuclei in the GCR with one {sub 96}Cm candidate event, and a low {sub 82}Pb/{sub 78}Pt ratio consistent with other experiments. The probability of the existence of a transuranic component is estimated as 96%, while the most likely {sub 92}U/{sub 90}Th ratio is found to be 0.4 within a wide 70% confidence interval ranging from 0 to 0.96. Overall, the results are consistent with a volatility-based acceleration bias and source material which is mainly ordinary interstellar medium material with some recent contamination by freshly synthesized material. Uncertainty in the key {sub 92}U/{sub 90}Th ratio is dominated by statistical errors resulting from the small sample size and any improved determination will thus require an experiment with a substantially larger exposure factor than the UHCRE.

Donnelly, J. [Dublin Institute of Technology (DIT), School of Physics, Kevin Street, Dublin 8 (Ireland); Thompson, A.; O'Sullivan, D.; Daly, J.; Drury, L. [School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Domingo, V.; Wenzel, K.-P. [European Space Research and Technology Centre (ESTEC), Keplerlaan 1, Postbus 299, 2200 AG Noordwijk (Netherlands)

2012-03-01

440

Galactic cosmic ray origin sites: Supernova remnants and superbubbles  

NASA Astrophysics Data System (ADS)

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 information on the composition of accelerated particles.

Bykov, A. M.; Ellison, D. C.; Gladilin, P. E.; Osipov, S. M.

2012-12-01

441

Voyager-1 Observations of MeV Ions and Electrons in the Vicinity of the Heliospheric Termination Shock  

NASA Astrophysics Data System (ADS)

Beginning in 2002.5 at a heliospheric distance of some 85AU, the CRS (Cosmic Ray Subsystem) experiment on Voyager-1 observed two large increases in MeV ions and electrons accompanied by more modest increases in Galactic and Anomaloous cosmic rays (GCR and ACRs). The first event persisted for some 6.5 months and was terminated by the passage of a large outward moving interplanetary disturbance. The second event, which began in 2003.62, is still in progress more than a year later. We have interpreted these events as the expected energetic particle precursors as Voyager-1 approaches the heliospheric termination shock and we have termed them TSP (Termination Shock Particle) increases. There are small, but significant, differences between TSP 1 and 2 both in the time history of the ions and electrons and in the short term (13 - 52 day) variations. In addition the GCR and ACR flux levels are somewhat smaller for the 2nd event. These TSP events have not yet been observed at Voyager-2, which is at a heliocentric distance some 18AU less than Voyager-1. However, at Voyager-2 there is a remarkable series of solar/interplanetary energetic particle events associated with specific episodes of solar activity. The effects of these interplanetary transients is clearly evident in the time history of the Voyager-1 TSPs, thus providing another means of probing this new region of space.

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

2004-12-01